A polyester compatibilizer and its preparation method and application

Abstract

The invention discloses a polyester compatibilizer, which is a lactide, glycolide, ε-caprolactone copolymer modified by isocyanate functionalization, and its molecular weight is about 5000-25000, and molecular weight distribution index is 1.1-1.3, and functionality is 3. The present invention also discloses a preparation method of the polyester compatibilizer, which is used to initiate lactide, glycolide and ε-caprolactone ring-opening copolymerization with triol to obtain a branched polyester copolymer, and toluene and excess diisocyanate are added to react the copolyester with isocyanate, and then triethylamine is removed by vacuum distillation, excess diisocyanate is washed away, and residual solvent is removed by vacuum distillation. The polyester compatibilizer prepared by the method of the present invention has higher volume expansion reaction efficiency, has a good volume expansion effect on all kinds of biodegradable polymers, and has little impact on resin processing properties. The present invention also discloses the application of the polyester compatibilizer.

Description

Technical Field

[0001] The invention belongs to the field of polymer synthesis, and particularly relates to the synthesis of an epoxy functionalized modified hydrocarbon resin, and in particular to the synthesis of a polyester compatibilizer. Background Art

[0002] Plastics are ubiquitous in our daily lives, greatly facilitating our lives. However, in recent years, coupled with resource scarcity, our overreliance on plastics has led to further environmental pollution. Most polymer materials are non-degradable or difficult to degrade. Biodegradable plastics technologies have advanced rapidly in recent years, and a large number of biodegradable plastics have entered mass production. Common biodegradable plastics are primarily biodegradable polyesters, such as polybutylene terephthalate-adipate (PBAT), polybutylene succinate (PBS), polylactic acid (PLA), polycaprolactone (PCL), and polyglycolic acid (PGA). Some of these materials exhibit excellent ductility, elongation at break, and blown film properties; others exhibit high strength, excellent heat resistance, good barrier properties, excellent low-temperature toughness, bacterial resistance, and biocompatibility. However, each also has drawbacks, including low heat deformation temperatures, low-temperature brittleness, poor processing properties, poor transparency, and slow degradation. Therefore, in most cases, it is necessary to select two or more materials for blending according to the final use of the material to prepare a material with qualified performance.

[0003] However, the compatibility between these different types of polyesters is poor, resulting in poor mechanical properties of the prepared composite materials. Therefore, it is necessary to improve the compatibility between the two. Existing compatibilizers mainly include physical compatibilizers and reactive compatibilizers. The principle of physical compatibilization is to prepare amphiphilic block copolymers, such as those described in patent documents CN102060986A and CN104725620A. Reactive compatibilization is the synthesis of compounds containing multifunctional groups that can react with active hydrogen, which react with the terminal hydroxyl groups of various polyesters to couple and improve the compatibility of polyesters. For example, patent documents CN102504506A, CN102516729A, CN102604348A, CN103113729A, CN103571158A, CN111378259A, CN109721977B, etc. use polyanhydrides, polyisocyanates, bisoxazolines, epoxy compounds or mixtures thereof. BASF and Shaanxi Chemical Research Institute have developed a low molecular weight copolymer of glycidyl methacrylate-styrene-acrylate, which is also a compatibilizer for epoxidation.

[0004] However, these compatibilizers do not provide ideal compatibilization effects during use. During reactive blending, chain extension within different polyester types is dominant, while coupling compatibilization between different polyesters is weak. As a result, the polyester melt index increases significantly after use, adversely affecting material processing performance, especially injection molding and thin-wall injection molding. They also increase resin molecular branching and reduce elongation at break. Summary of the Invention

[0005] Reactive polyester compatibilizers react with the terminal hydroxyl groups of polyester molecules through their active functional groups, resulting in coupling reactions between terminal hydroxyl groups of different polyesters, thereby improving their compatibility. However, most existing compatibilizers are small-molecule additives, or their chemical structures have solubility parameters similar to those of polyesters, making the compatibilizers highly soluble in polyesters. Therefore, during blending, these compatibilizers mostly dissolve in the dispersed phases of different polyesters. The coupling of terminal hydroxyl groups mostly occurs between similar polyesters, acting more as chain extenders, while only a small portion undergoes coupling reactions between different polyester molecules, acting as a compatibilizer. As a result, the compatibilization effect is poor, the melt index is reduced, and injection molding performance deteriorates. Furthermore, to improve reaction efficiency, existing reactive compatibilizers have high functionality, which leads to a significant decrease in the elongation at break of the blended material.

[0006] The invention provides a polyester compatibilizer. The polyester compatibilizer is an isocyanate functionalized modified lactide, glycolide and ε-caprolactone copolymer, has a molecular weight of 5000-25000, a molecular weight distribution index of 1.1-1.3 and a functionality of 3.

[0007] The present invention also provides a method for preparing a polyester compatibilizer. The prepared polyester compatibilizer has a higher compatibilization reaction efficiency, has less impact on the processing properties of the polyester blend, and maintains a good elongation at break.

[0008] The preparation method of the polyester compatibilizer of the present invention comprises the following steps:

[0009] 1) adding triol, ε-caprolactone, lactide, glycolide, and a catalyst into a reactor to carry out a ring-opening copolymerization reaction to obtain a polymer;

[0010] 2) adding toluene to the polymer obtained in the first step to dissolve the polymer obtained in the first step, wherein the amount of toluene used is preferably 2-5 times the mass of the polymer;

[0011] 3) gradually adding the polymer solution obtained in the second step to an excess of diisocyanate containing the catalyst triethylamine at 70°C-110°C, reacting for 0.5-3 hours after the addition is complete, and then cooling to 40-60°C;

[0012] 4) Concentrating the reaction solution obtained in the third step by vacuum distillation at 40-60° C. and 0.01-10 kPa absolute pressure until the total toluene content of the reactants is ≤70% wt and ≥30% wt, while removing triethylamine;

[0013] 5) Add aqueous methanol to the reaction product obtained in step 4, stir, and then stand for separation to obtain a lower polymer / toluene layer, and repeat this process 1-6 times;

[0014] 6) The toluene layer obtained in the fifth step is distilled under reduced pressure at an absolute pressure of 0.01-1 KPa, and the temperature is gradually raised to 140° C. and then maintained for 15 minutes to finally obtain a polyester compatibilizer;

[0015] In step 1) of the present invention, the molar ratio of the total mol amount of ε-caprolactone, lactide and glycolide to the molar ratio of the triol is 50-200:1; preferably, 90-150:1.

[0016] In step 1) of the present invention, the molar amount of each of the three esters is 20%-60% based on the total molar amount of ε-caprolactone, lactide and glycolide.

[0017] In the present invention, the molar ratio of the triol to the diisocyanate is 1:6-1:12; preferably, 1:8-1:12.

[0018] In step 1) of the present invention, the triol is one or both of glycerol and trimethylolpropane.

[0019] In step 1) of the present invention, the preferred process conditions for the ring-opening copolymerization reaction are: temperature of 130° C. to 180° C. and reaction time of 0.5 to 5 h.

[0020] In step 1) of the present invention, the catalyst is one or more of stannous octoate, antimony trioxide, and tetrabutyl titanate.

[0021] In step 1) of the present invention, the amount of the catalyst used is 0.01-0.1% wt of the total mass of ε-caprolactone, lactide and glycolide; preferably, 0.03-0.08% wt.

[0022] In step 3) of the present invention, the diisocyanate used is one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI).

[0023] In step 5) of the present invention, the amount of the aqueous methanol is 0.5-3 times the mass of the product obtained in the fourth step, and the water content in the aqueous methanol accounts for 1%-10% wt of the total mass of the aqueous methanol.

[0024] The present invention also provides a polyester compatibilizer prepared by the method.

[0025] The polyester compatibilizer is an isocyanate functionalized modified copolymer of lactide, glycolide and ε-caprolactone, with a molecular weight of 5000-25000, a molecular weight distribution index of 1.1-1.3 and a functionality of 3.

[0026] The present invention also provides application of the polyester compatibilizer in polyester blending processing.

[0027] The present invention also provides a biodegradable polyester composition, comprising a polyester polymer, an inorganic filler, and a polyester compatibilizer prepared by the method of the present invention.

[0028] The composition preferably comprises the following components: 1) two or more of poly(butylene terephthalate-adipate-poly(butylene terephthalate) PBAT, poly(butylene succinate) PBS, poly(lactic acid) PLA, poly(caprolactone) PCL, poly(glycolic acid) PGA, poly(propylene carbonate) PPC, poly(butylene terephthalate-succinate) PBST, poly(butylene adipate-succinate) PBSA, glycolide-lactide copolymer PLGA, and starch; 2) the mass of the polyester compatibilizer prepared by the method of the present invention is 0.1-0.5%wt of the mass of the polymer; 3) the inorganic filler is calcium carbonate or talc, the mass of which is 0-30%wt of the mass of component 1).

[0029] The present invention also provides application of the biodegradable polyester composition in disposable biodegradable packaging films, biodegradable agricultural films, and disposable food tableware.

[0030] The beneficial effects of the present invention include: the method of the present invention can prepare a polyester compatibilizer with excellent performance, the compatibilization reaction efficiency is low, the processing performance of the polyester is not affected, and the mechanical properties are kept good. DETAILED DESCRIPTION

[0031] The present invention is further described in detail with reference to the following specific examples. Except for the contents specifically mentioned below, the processes, conditions, experimental methods, etc. for implementing the present invention are common knowledge and common common sense in the field and are not particularly limited by the present invention.

[0032] Reference Examples 1-4

[0033] Reference Examples 1-4 provide a variety of compatibilizer formulations, as shown in Table 1.

[0034] Table 1

[0035]

[0036]

[0037] Examples 1-5

[0038] As shown in Table 2, triol, ε-caprolactone, lactide, glycolide, and catalyst were added to a reactor, heated to 150°C, and ring-opening copolymerization was carried out in a molten state; after reacting for 2 hours, toluene 3 times the mass of the polymer was added to dissolve the copolyester.

[0039] Heat the diisocyanate to 100°C, add triethylamine at a concentration of 0.1% by weight of the isocyanate, and gradually add the polymer solution obtained in the second step to the diisocyanate. After the addition is complete, continue the reaction for 2.5 hours, and then cool to 50°C.

[0040] Maintaining the material temperature at 50°C, gradually establish vacuum to an absolute pressure of 0.1 KPa and maintain it for 15 minutes, and then perform reduced pressure distillation. After the reduced pressure distillation is completed, the triethylamine has been completely removed.

[0041] Then, an equal amount of aqueous methanol (water content 2%) was added to the reactants, stirred, and allowed to stand for separation to obtain the lower polymer / toluene layer, and this washing process was repeated 4 times;

[0042] The toluene layer obtained after the final washing was distilled under reduced pressure at an absolute pressure of 0.1 KPa, and the temperature was gradually raised to 140°C and then maintained for 15 minutes to obtain a polyester compatibilizer.

[0043] Table 2

[0044] Example 1 Example 2 Example 3 Example 4 Example 5 Glycerol, mol 1 0.5 0 0.3 0.7 Trimethylolpropane, mol 0 0.5 1 0.7 0.3 Lactide, mol 20 60 50 60 80 ε-Caprolactone, mol 20 20 50 60 60 Glycolide, mol 10 20 50 60 60 Stannous octoate, %wt 0.01 0.03 0.05 0.07 0.1 HDI,mol 2 3 10 0 0 TDI,mol 2 6 0 9 0 MDI,mol 2 3 0 0 10 Polyester compatibilizer Mn 5320 13191 15840 20943 24508

[0045] Note: The amount of stannous octoate is calculated based on the total mass of cyclic esters (ε-caprolactone, lactide, glycolide) as 100%.

[0046] Formulation application test results

[0047] Different types of biodegradable polyesters and different types of compatibilizers were mixed evenly through a twin-screw extruder, and then the physical properties of the mixture were tested. The results are as follows:

[0048] Polylactic acid PLA: produced by Total-Corbijn, brand L175;

[0049] Polybutylene adipate terephthalate PBAT: produced by BASF, brand name Ecoflex C1200;

[0050] Polyglycolic acid PGA: Kureha Chemical, kuredux PGA.

[0051] Polycaprolactone PCL: provided by Hunan Juren Chemical, brand PCL6800.

[0052] The tensile properties of the specimens were tested using a universal electronic tensile testing machine (Instron 4465, Instron Corp., USA) according to ASTM D638, specimen specifications: 20 mm × 4 mm × 0.8 mm, load: 2.00 kN, tensile rate: 5.00 mm / min.

[0053] The impact strength of the specimens was tested using a pendulum impact tester (Izo / Charpy, RAY-RAN Test Equipment Ltd., UK) according to ASTM D790. The specimen specifications were: 63.5 mm × 12.7 mm × 3 mm, the pendulum weight was 0.818 kg, and the pendulum speed was 3.5 m / s.

[0054] Table 3-7 shows the physical properties of different polyesters and different polyester compatibilizers after being evenly mixed by twin-screw extruder.

[0055] Table 3

[0056]

[0057] Table 3 shows that when the polyester compatibilizer is used at a dosage of 0.3%wt of the polyester dosage, the polyester compatibilizers prepared in Examples 1-5 of the present invention can produce a better compatibilization effect compared to the reference. The compatibility of PBAT and PLA in the mixtures containing the polyester compatibilizers prepared in Examples 1-5 of the present invention shown in the above table is increased. PBAT has a toughening effect on the original continuous phase of PLA, improving the material toughness and notched impact strength. At the same time, the tensile strength remains at a high level, the melt index changes little before and after blending, and the melt processing performance remains almost unchanged.

[0058] Table 4

[0059]

[0060] Table 4 compares the performance results, showing that the polyester compatibilizers prepared in Examples 1-5 of the present invention also have a high-efficiency compatibilization effect in the PCL / PGA blend system similar to that in the PBAT / PLA system, while also improving the tensile strength and elongation at break of the material.

[0061] Table 5

[0062]

[0063]

[0064] Thermoplastic starch is a commonly used biodegradable polymer filler. Starch granules offer good hardness and reinforcement, but its compatibility with most biodegradable polyesters is poor, and excessive addition can easily affect the material's mechanical properties. However, the polyester compatibilizers prepared using Examples 1-5 of the present invention significantly improve the mechanical properties of the blended materials. The results in Table 5 show that, for the same starch-added formulations, the blends containing the reference examples exhibit lower tensile strength and lower elongation at break, while the blends containing the polyester compatibilizers prepared using Examples 1-5 of the present invention exhibit superior tensile strength and elongation at break.

[0065] The protection content of the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the present invention, changes and advantages that can be thought of by those skilled in the art are included in the present invention and are protected by the appended claims.

Claims

1. A polyester compatibilizer, characterized in that The polyester compatibilizer is an isocyanate functionalized modified lactide, glycolide, and ε-caprolactone copolymer with a molecular weight of 5000-25000, a molecular weight distribution index of 1.1-1.3, and a functionality of 3; The preparation method of the polyester compatibilizer comprises the following steps: 1) Add triol, ε-caprolactone, lactide, glycolide and catalyst into a reactor to carry out ring-opening copolymerization to obtain a polymer; 2) adding toluene to the polymer obtained in the first step, wherein the amount of toluene is 2-5 times the mass of the polymer, and dissolving the polymer to obtain a polymer solution; 3) Gradually add the polymer solution obtained in the second step to an excess of diisocyanate containing the catalyst triethylamine at 70-110°C. After the addition is complete, react for 0.5-3 hours, then cool to 40-60°C. 4) Concentrate the reaction solution obtained in the third step by vacuum distillation at 40-60°C and 0.01-10 kPa absolute pressure until the total toluene content of the reactants is ≤70%wt and ≥30%wt, while removing triethylamine; 5) Add aqueous methanol to the reaction mixture obtained in step 4, stir, and then allow to stand to separate the layers. Separate the layers to obtain a lower polymer / toluene layer, and repeat this process 1-6 times; 6) The toluene layer obtained in the fifth step is distilled under reduced pressure at an absolute pressure of 0.01-1 kPa, and the temperature is gradually raised to 140°C and maintained for 15 minutes to obtain a polyester compatibilizer; In step 1), the molar ratio of the total mol amount of ε-caprolactone, lactide and glycolide to the triol is 50-200:1; the molar amount of each of the three esters is 20%-60% based on the total mol amount of ε-caprolactone, lactide and glycolide; and the molar ratio of the triol to the diisocyanate is 1:6-1:

12.

2. The polyester compatibilizer according to claim 1, wherein In step 1), the temperature of the ring-opening copolymerization reaction is 130°C-180°C, and the reaction time is 0.5-5h; The catalyst is one or more of stannous octoate, antimony trioxide, and tetrabutyl titanate; The amount of the catalyst used is 0.01-0.1%wt of the total mass of the ε-caprolactone, lactide and glycolide; The triol is one or both of glycerol and trimethylolpropane.

3. The polyester compatibilizer according to claim 1, wherein In step 3), the diisocyanate is one or more of toluene diisocyanate TDI, diphenylmethane diisocyanate MDI, and hexamethylene diisocyanate HDI.

4. The polyester compatibilizer according to claim 1, wherein In step 5), the amount of the aqueous methanol used is 0.5-3 times the mass of the reactants obtained in the fourth step; wherein the water content in the aqueous methanol accounts for 1%-10%wt of the total mass of the aqueous methanol.

5. A method for preparing a polyester compatibilizer, characterized in that: The following steps are involved: 1) Add triol, ε-caprolactone, lactide, glycolide and catalyst into a reactor to carry out ring-opening copolymerization to obtain a polymer; 2) adding toluene to the polymer obtained in the first step, wherein the amount of toluene is 2-5 times the mass of the polymer, and dissolving the polymer to obtain a polymer solution; 3) Gradually add the polymer solution obtained in the second step to an excess of diisocyanate containing the catalyst triethylamine at 70-110°C. After the addition is complete, react for 0.5-3 hours, then cool to 40-60°C. 4) Concentrate the reaction solution obtained in the third step by vacuum distillation at 40-60°C and 0.01-10 kPa absolute pressure until the total toluene content of the reactants is ≤70%wt and ≥30%wt, while removing triethylamine; 5) Add aqueous methanol to the reaction mixture obtained in step 4, stir, and then allow to stand to separate the layers. Separate the layers to obtain a lower polymer / toluene layer, and repeat this process 1-6 times; 6) The toluene layer obtained in the fifth step is distilled under reduced pressure at an absolute pressure of 0.01-1 kPa, and the temperature is gradually raised to 140°C and maintained for 15 minutes to obtain a polyester compatibilizer; In step 1), the molar ratio of the total mol amount of ε-caprolactone, lactide and glycolide to the triol is 50-200:1; the molar amount of each of the three esters is 20%-60% based on the total mol amount of ε-caprolactone, lactide and glycolide; and the molar ratio of the triol to the diisocyanate is 1:6-1:

12.

6. The method for preparing a polyester compatibilizer according to claim 5, wherein: In step 1), the temperature of the ring-opening copolymerization reaction is 130°C-180°C, and the reaction time is 0.5-5h; The catalyst is one or more of stannous octoate, antimony trioxide, and tetrabutyl titanate; The amount of the catalyst used is 0.01-0.1%wt of the total mass of the ε-caprolactone, lactide and glycolide; The triol is one or both of glycerol and trimethylolpropane.

7. The method for preparing a polyester compatibilizer according to claim 5, wherein: In step 3), the diisocyanate is one or more of toluene diisocyanate TDI, diphenylmethane diisocyanate MDI, and hexamethylene diisocyanate HDI.

8. The method for preparing a polyester compatibilizer according to claim 5, wherein: In step 5), the amount of the aqueous methanol used is 0.5-3 times the mass of the reactants obtained in the fourth step; wherein the water content in the aqueous methanol accounts for 1%-10%wt of the total mass of the aqueous methanol.

9. A polyester compatibilizer prepared by the method according to any one of claims 5 to 8.

10. Use of the polyester compatibilizer according to claim 1 or 9 in polyester blending processing.

11. A biodegradable polyester composition, characterized in that The composition comprises a polyester polymer, an inorganic filler, and the polyester compatibilizer according to claim 1 or 9.

12. The composition according to claim 11, wherein The polyester polymer includes two or more of poly(butylene terephthalate-adipate-polybutylene ester) (PBAT), poly(butylene succinate-polybutylene ester) (PBS), poly(lactic acid) (PLA), poly(caprolactone) (PCL), poly(glycolic acid) (PGA), poly(propylene carbonate) (PPC), poly(butylene terephthalate-succinate-polybutylene ester) (PBST), poly(butylene adipate-succinate-polybutylene ester) (PBSA), glycolide-lactide copolymer (PLGA), and starch; the mass of the polyester compatibilizer is 0.1-0.5%wt of the mass of the polyester polymer; the inorganic filler is calcium carbonate or talc, and the mass of the inorganic filler is 0-30%wt of the mass of the polyester polymer.

13. Use of the biodegradable polyester composition according to claim 11 or 12 in disposable biodegradable packaging films, biodegradable agricultural films, and disposable food tableware.

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