Composite catalytic initiator and method for reducing odor of epsilon-caprolactone homopolymer

Abstract

The invention belongs to the field of polymers, and particularly relates to a composite catalytic initiator for reducing odor of an epsilon-caprolactone homopolymer, which comprises a component A and a component B, the component A is a compound with a structure as shown in a formula 1 # imgabs 0 # and / or a formula 2 # imgabs 1 #; and the component B is a compound with a structure as shown in a formula 3 # imgabs2 #. R < 1 > to R < 3 > are independently alkyl groups with 1 to 6 carbon atoms; r4 is H or alkyl of C1-C3, and n is an integer of 1-3. The invention also comprises a method for preparing the low-odor polycaprolactone homopolymer by using the composite catalytic initiator. According to the method, the homopolymerization effect can be effectively improved, and the odor can be effectively reduced.

Description

Technical Field

[0001] The invention relates to a method for preparing a low-odor ε-caprolactone homopolymer, belonging to the technical field of degradable resin synthesis. Background Art

[0002] Thermoplastic polycaprolactone (PCL) has many advantages such as good biodegradability, biocompatibility, shape memory properties, etc. It can be used as medical orthopedic splints, medical positioning membranes, absorbable surgical sutures, medical bone nails and in vivo implantable stents.

[0003] At present, the catalysts for the ring-opening polymerization of caprolactone reported in domestic and foreign literature mainly include tin, titanium, rare earth metal compound systems, active hydrogen, enzyme catalysis systems, etc., but the existing reports have the following shortcomings: ① The polycaprolactone product has a strong odor, mainly sour and smelly, which comes from the organic acid substances introduced in the preparation process and is difficult to use in high-end medical fields. ② The catalytic activity is low, the amount of catalyst required is large, the conversion rate of ε-caprolactone is slow and the conversion rate is low. ③ The catalyst is expensive (such as rare earth metal catalyst). ④ The required polymerization reaction time is long. ⑤ The reaction conditions are harsh and are mostly carried out in a vacuum drying oven.

[0004] A Chinese patent (application number CN200910165299.5) discloses a method for synthesizing polycaprolactone, which is completed by a one-step reaction, i.e., the bulk ring-opening polymerization of caprolactone initiated by 1st to 3rd generation alkynylated poly(amide-amine) is used to prepare terminal alkynylated linear or fan-shaped polycaprolactone. The polymerization temperature is 130°C and the reaction time is 24h. The reaction time required for this method is relatively long and the yield is relatively low.

[0005] A Chinese patent (application number CN201610186268.8) discloses a metal complex for efficient and controllable ring opening of ε-caprolactone, specifically a thiourea metal salt, which is suitable for bulk polymerization and melt polymerization processes of ε-caprolactone, and is also suitable for slow and controllable polymerization in solution, but the cost of raw materials required to synthesize the thiourea metal salt is relatively high.

[0006] A Chinese patent (application number CN201810980422.8) discloses the synthesis of a β-pyridine enamine bidentate aluminum complex and catalytic ring-opening polymerization of ε-caprolactone. 2-(2-pyridyl)-acetophenone is subjected to a condensation reaction with aromatic amines containing different substituents to obtain a ligand containing two nitrogen atoms, which is then coordinated with alkyl aluminum to synthesize a metal complex of β-pyridine enamine bidentate aluminum. It can be used to catalyze the ring-opening polymerization of ε-caprolactone, with a polymerization reaction temperature of 70 to 80°C and a reaction time of 20 to 240 minutes. This method has many steps.

[0007] Mary F. Mahon et al. (Inorganic Chemistry 2006, 45(5): 2282–2287.) reported the synthesis, X-ray structure and application of a novel compound aryloxytitanium in the ring-opening polymerization of ε-caprolactone. A series of catechol titanium were prepared and characterized by single crystal X-ray diffraction studies. The electronic and steric effects of the ligands were studied. The novel compound aryloxytitanium was used for the ring-opening polymerization of ε-caprolactone to obtain polycaprolactone with a maximum yield of 79% at room temperature. The yield of polycaprolactone obtained by this method is relatively low. Summary of the invention

[0008] In view of the problems in the prior art that ε-caprolactone homopolymer contains carboxylic acid, has a strong odor, and has a low homopolymer molecular weight, the first purpose of the present invention is to provide a composite catalytic initiator for reducing the odor of ε-caprolactone homopolymer, aiming to effectively reduce the product odor and improve the homopolymerization effect.

[0009] The second object of the present invention is to provide a method for preparing a low-odor ε-caprolactone homopolymer, aiming to reduce the odor of the polycaprolactone product and improve the molecular weight of the product.

[0010] The third object of the present invention is to provide low-odor polycaprolactone obtained by the preparation method.

[0011] A composite catalytic initiator for reducing the odor of ε-caprolactone homopolymer, comprising component A and component B;

[0012] The component A is a compound having a structure of Formula 1 and / or Formula 2;

[0013] The component B is a compound having a structure of formula 3;

[0014]

[0015] The R1-R3 are independently C1-C6 alkyl groups; the R4 is H or C1-C3 alkyl group, and the n is an integer of 1-3.

[0016] The present invention innovatively finds that the combination of component A and component B of the structure can unexpectedly achieve synergy, improve the efficiency and effect of the ε-caprolactone homopolymerization reaction, help improve the homopolymerization conversion rate and the molecular weight of the homopolymerization product, and not only that, but also reduce or even avoid the residual odor substances in the product.

[0017] In the present invention, the combination of component A and component B in the structure is the key to synergistically reduce odor and simultaneously improve the homopolymerization effect. In the present invention, thanks to the synergistic combination of components A and B, excellent polymerization effect can be obtained at a low catalytic amount, and odor can be synergistically reduced.

[0018] Preferably, in Formula 1, R1 is a C3-C4 straight-chain or branched alkyl group, preferably an isopropyl group.

[0019] Preferably, in Formula 2, R2 is a C1-C2 straight or branched alkyl group, preferably a methyl group;

[0020] The R3 is a C3-C5 straight-chain or branched alkyl group, preferably an n-butyl group.

[0021] Preferably, in Formula 3, n is 2, and R4 is H.

[0022] Preferably, the molar ratio of component A to component B is 1:3 to 3:1, preferably 1:2 to 2:1, and more preferably 1:2 to 1:1.

[0023] In the present invention, the composite catalyst initiator consists of component A and component B.

[0024] The present invention also provides a method for reducing the odor of ε-caprolactone homopolymer (the present invention is also called a method for synthesizing low-odor polycaprolactone), wherein ε-caprolactone is ring-opening polymerized under the catalysis of the composite catalyst initiator to obtain a polycaprolactone homopolymer with reduced odor.

[0025] In the present invention, the molar ratio of component A or component B in the composite catalyst initiator to ε-caprolactone is 1:5000 to 1:700. Preferably, considering the treatment effect and cost, the molar ratio of component A to ε-caprolactone is 1:950 to 1100. The molar ratio of component B to ε-caprolactone is 1:700 to 1000.

[0026] Preferably, the temperature of the ring-opening polymerization is 145 to 180°C, preferably 155 to 165°C.

[0027] Preferably, the time of the ring-opening polymerization is not less than 150 min.

[0028] Preferably, when the composite catalytic initiator includes Formula 1 and Formula 3, the time of the ring-opening polymerization is preferably 150 to 180 minutes;

[0029] Preferably, when the composite catalytic initiator comprises Formula 2 and Formula 3, the time of the ring-opening polymerization is preferably 2.5 to 10 hours, and more preferably 6.5 to 10 hours.

[0030] The invention also provides a caprolactone homopolymer-polycaprolactone prepared by the method.

[0031] Beneficial Effects

[0032] The present invention innovatively combines component A and component B of the structure, thus achieving synergy and obtaining a good catalytic conversion effect at a lower dosage. Moreover, it can also effectively reduce odor substances in the product, thus having positive industrial value.

[0033] The technical solution of the present invention adopts a special catalytic initiation system, which is safe and efficient. Under the temperature condition of 155-165°C, the reaction speed is fast, the ε-caprolactone conversion speed is fast, and the polycaprolactone product has low odor. Compared with other methods for producing polycaprolactone, the catalytic initiation system adopted in the technical solution of the present invention has the advantages of high activity, small dosage, fast reaction speed, short reaction time, fast ε-caprolactone conversion speed, and low odor of polycaprolactone product.

[0034] The technical solution of the present invention can adopt a bulk polymerization method, and the production process is simple and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of the product in Example 1;

[0036] Figure 2 This is the GPC spectrum of the product in Group D of Example 1;

[0037] Figure 3 This is the GPC spectrum of the product of Group E in Example 1;

[0038] Figure 4 is the hydrogen nuclear magnetic resonance spectrum of the product in Example 2;

[0039] Figure 5 This is the GPC spectrum of the product in Group E of Example 2;

[0040] Figure 6 This is the GPC spectrum of the product of Group F in Example 2;

[0041] Figure 7 This is the GPC spectrum of the product of Group G in Example 2;

[0042] Figure 8 The H NMR spectrum of the product in Group D of Example 1 (with emphasis on 11-12 ppm);

[0043] Fig. 9 The H NMR spectrum of the product in Group E of Example 1 (with emphasis on 11-12 ppm);

[0044] Fig.10 The H NMR spectrum of the product in Group E of Example 2 (with emphasis on 11-12 ppm);

[0045] Fig.11The H NMR spectrum of the product in Group F of Example 2 (with emphasis on 11-12 ppm);

[0046] Fig.12 The H NMR spectrum of the product in Group G of Example 2 (with emphasis on 11-12 ppm); DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with the embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process.

[0048] The composite catalytic initiator of the present invention may be, for example, a combination of Formula 1 and Formula 3, or a combination of Formula 2 and Formula 3.

[0049] When the composite catalytic initiator is a combination of Formula 1 and Formula 3 (also referred to as composite catalyst A), as a typical example, Formula 1 may preferably be Formula 1-A, which is a compound of Formula 1 in which R1 is isopropyl; Formula 3 may be Formula 3-A It is a compound of formula 3, wherein R4 is H and n is 2. Preferably, in this scheme, the molar ratio of formula 1 to formula 3 is 1:2 to 2:1, preferably 1:1.

[0050] When the composite catalytic initiator is a combination of Formula 2 and Formula 3 (also a component of composite catalyst B), as a typical example, Formula 2 may preferably be Formula 2-A, which is a compound of Formula 2 in which R2 is a methoxy group and R3 is a n-butyl group; Formula 3 may be Formula 3-A, which is a compound of Formula 3 in which R4 is H and n is 2. Preferably, in this solution, the molar ratio of Formula 1 to Formula 3 is 1:3 to 3:1, preferably 7:10.

[0051] In the present invention, the components of the composite catalyst can be mixed and contacted with ε-caprolactone in the form of a mixture, or each can be mixed and contacted with ε-caprolactone in sequence independently, and then the temperature is increased to carry out a ring-opening homopolymerization reaction to reduce the synthetic odor, thereby obtaining low-odor polycaprolactone.

[0052] In the present invention, when the composite catalyst is composite catalyst A, the molar ratio of Formula 1 to ε-caprolactone is 1:5000 to 1:700, and more preferably 1:950 to 1100. The molar ratio of Formula 1 to ε-caprolactone is 1:5000 to 1:700, and more preferably 1:700 to 1000. The temperature of the ring-opening polymerization stage is 140 to 175° C., and preferably 155 to 165° C. Considering the preparation efficiency and effect, the polymerization time is preferably 150 to 180 min.

[0053] In the present invention, when the composite catalyst is composite catalyst B, the molar ratio of formula 2 to ε-caprolactone is 1:5000 to 1:700, and more preferably 1:950 to 1100. The molar ratio of formula 3 to ε-caprolactone is 1:5000 to 1:700, and more preferably 1:700 to 1000. The reaction temperature of caprolactone ring-opening polymerization is 145 to 170° C., and preferably 155 to 165° C. Considering the preparation efficiency and effect, the polymerization time is preferably 5 to 10 hours, and more preferably 6.5 to 8.5 hours.

[0054] Example 1

[0055] Weigh 200.18g of ε-caprolactone, 0.12g of Formula 1-A and 0.05g of Formula 3-A, respectively, add them into a 500ml three-necked flask, install a thermometer and a condenser, introduce nitrogen, open the condensate inlet and outlet, start the stirring device, make sure that the system is sealed, heat the heating jacket, and after the liquid temperature in the three-necked flask reaches 160°C, react for different times (Group A: 30min; Group B: 60min; Group C: 120min; Group D: 150min; Group B: 154min);, and perform nuclear magnetic resonance tests on the products at different times. The results are shown in the table below. Figure 1 , the results of different processing times are:

[0056] Group A: caprolactone conversion rate was 4.85%;

[0057] Group B: caprolactone conversion rate was 5.94%;

[0058] Group C: caprolactone conversion rate was 24.63%;

[0059] Group D: Caprolactone conversion rate is 85.21%, polycaprolactone number average molecular weight is 78490, distribution is 1.38, product H NMR spectrum is attached Figure 1 , GPC spectrum is attached Figure 2 The characteristic peak of the -COOH hydrogen proton of the typical odor substance organic carboxylic acid is at 11-12ppm. The product does not have this characteristic peak at 11-12ppm, that is, there is no typical odor substance organic carboxylic acid in the product. The NMR spectrum is as shown in the attached Figure 8 shown.

[0060] Group E: Caprolactone conversion rate is 88.64%, polycaprolactone number average molecular weight is 90111, distribution is 1.33, product H NMR spectrum is attached Figure 1 , GPC spectrum is attached Figure 3 The characteristic peak of the -COOH hydrogen proton of the typical odor substance organic carboxylic acid is at 11-12ppm. The product does not have this characteristic peak at 11-12ppm, that is, there is no typical odor substance organic carboxylic acid in the product. The NMR spectrum is as shown in the attached Fig. 9 shown.

[0061] Example 2

[0062] Weigh 200.80g of ε-caprolactone, 0.16g of Formula 2-A and 0.07g of Formula 3-A, respectively, add them into a 500ml three-necked flask, install a thermometer and a condenser, introduce nitrogen, open the condensate inlet and outlet, start the stirring device, and after confirming that the system is sealed, heat the heating jacket until the liquid temperature in the three-necked flask reaches 160°C. React for different reaction times t1, and detect and identify the products at different reaction times. The nuclear magnetic resonance hydrogen spectra of the products at different reaction times are shown in the attached Figure 4 The conversion rate and product properties of the products at different times are:

[0063] Group A: t1 is 1h, after 1h of reaction, the caprolactone conversion rate is 15.52%;

[0064] Group B: t1 is 2h, caprolactone conversion rate is 28.54%;

[0065] Group C: t1 was 3 h, and the caprolactone conversion rate was 43.74%;

[0066] Group D: t1 was 4 h, and the caprolactone conversion rate was 58.82%;

[0067] Group E: t1 is 5h, caprolactone conversion is 71.48%, product number average molecular weight is 37788, distribution is 1.55, product H NMR spectrum is attached Figure 1 , product GPC spectrum is attached Figure 5 The characteristic peak of the -COOH hydrogen proton of the typical odor substance organic carboxylic acid is at 11-12ppm. The product does not have this characteristic peak at 11-12ppm, that is, there is no typical odor substance organic carboxylic acid in the product. The NMR spectrum is as shown in the attached Fig.10 shown.

[0068] Group F: t1 is 6h, caprolactone conversion is 75.70%, product number average molecular weight is 54953, distribution is 1.31, product H NMR spectrum is attached Figure 1 , product GPC spectrum is attached Figure 6 The characteristic peak of the -COOH hydrogen proton of the typical odor substance organic carboxylic acid is at 11-12ppm. The product does not have this characteristic peak at 11-12ppm, that is, there is no typical odor substance organic carboxylic acid in the product. The NMR spectrum is as shown in the attached Fig.11 shown.

[0069] Group G: t1 is 7h, caprolactone conversion is 90.16%, product number average molecular weight is 53778, distribution is 1.43, product H NMR spectrum is attached Figure 1 , the product GPC spectrum is attached Figure 7The characteristic peak of the -COOH hydrogen proton of the typical odor substance organic carboxylic acid is at 11-12ppm. The product does not have this characteristic peak at 11-12ppm, that is, there is no typical odor substance organic carboxylic acid in the product. The NMR spectrum is as shown in the attached Fig.12 shown.

[0070] This invention is funded by the Hunan Science and Technology Innovation Program, Project No. 2021RC3138.

Claims

1. A composite catalyst initiator for reducing the odor of ε-caprolactone homopolymer, characterized in that: Containing ingredient A and ingredient B; The component A is a compound having a structure of Formula 1 and / or Formula 2; The component B is a compound having a structure of formula 3; The R1-R3 are independently C1-C6 alkyl groups; the R4 is H or C1-C3 alkyl group, and the n is an integer of 1-3.

2. The composite catalyst initiator according to claim 1, characterized in that In the formula 1, R1 is a C3-C4 straight-chain or branched alkyl group, preferably an isopropyl group.

3. The composite catalyst initiator according to claim 1, characterized in that In the formula 2, R2 is a C1-C2 straight chain or branched chain alkyl group, preferably a methyl group; The R3 is a C3-C5 straight-chain or branched alkyl group, preferably an n-butyl group.

4. The composite catalyst initiator according to claim 1, characterized in that In Formula 3, n is 2, and R4 is H.

5. The composite catalyst initiator according to any one of claims 1 to 4, characterized in that: The molar ratio of component A to component B is 1:3 to 3:1, preferably 1:2 to 2:1, and more preferably 1:2 to 1:

1.

6. The composite catalyst initiator according to any one of claims 1 to 5, characterized in that: It is composed of component A and component B.

7. A method for reducing the odor of ε-caprolactone homopolymer, characterized in that: The ε-caprolactone is subjected to ring-opening polymerization under the catalysis of the composite catalyst initiator described in any one of claims 1 to 6 to obtain a polycaprolactone homopolymer with reduced odor.

8. The method according to claim 7, characterized in that The molar ratio of component A or component B in the composite catalyst initiator to epsilon-caprolactone is 1:5000 to 1:

700.

9. The method according to claim 7 or 8, characterized in that The temperature of the ring-opening polymerization is 145 to 180°C, preferably 155 to 165°C.

10. The method according to any one of claims 7 to 9, characterized in that: The time of ring-opening polymerization is not less than 150 minutes; Preferably, when the composite catalytic initiator includes Formula 1 and Formula 3, the time of the ring-opening polymerization is preferably 150 to 180 minutes; Preferably, when the composite catalytic initiator comprises Formula 2 and Formula 3, the time of the ring-opening polymerization is preferably 2.5 to 10 hours, and more preferably 6.5 to 10 hours.

11. A polycaprolactone homopolymer obtained by the method according to any one of claims 7 to 10.

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