High-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate and preparation method thereof

Abstract

The invention discloses high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate and a preparation method thereof. The carbon dioxide-based polyester-polycarbonate composite material is prepared from 90 to 98 percent of carbon dioxide-based polyester-polycarbonate and 2 to 10 percent of a carbon dioxide-based polycarbonate or polyester-polycarbonate hard-soft-hard triblock structure elastomer. The hard segments at the two ends of the elastomer are a polycarbonate chain segment and a polyester chain segment containing rigid groups respectively, so that the elastomer has high glass transition temperature and good compatibility, and the situation that the two phases are incompatible is avoided; soft segments in the two elastomers are polycarbonate chain segments containing long-chain branches, and the soft segments have very low glass transition temperature, so that the effects of buffering stress and toughening are achieved. The special hard-soft-hard three-block structure elastomer is used as a toughening modifier, high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate can be prepared, and good tensile strength and light transmittance are still kept while the toughness and the processing performance of the material are effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of plastic processing, and more specifically, to a high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate and a preparation method thereof. Background Art

[0002] Polyester-polycarbonate terpolymers and quaternary copolymers prepared by copolymerizing carbon dioxide, epoxides, phthalic anhydride and / or tetrachlorophthalic anhydride are novel biodegradable plastics with high light transmittance and high barrier properties, and have great application scenarios in the food packaging field (CN 111378101A, J.CO2 Util.2021,49,101558, CN 111333825A, CN113929890A). Compared with the traditional poly(methyl ethylene carbonate) (PPC) prepared by copolymerizing propylene oxide and carbon dioxide, the polyester-polycarbonate material exhibits an elevated glass transition temperature (T g (>48 °C) and mechanical properties (>35 MPa), but a low elongation at break (<6%). Therefore, new methods are needed to improve the toughness of the polyester-polycarbonate material. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem that the existing biodegradable polyester-polycarbonate cannot have both high strength and high toughness, and to provide a high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite material and a preparation method thereof.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A carbon dioxide-based polycarbonate or polyester-polycarbonate hard-soft-hard triblock elastomer. For the polycarbonate elastomer, the middle soft segment is a polycarbonate chain segment containing long branches, and the two end hard segments are polycarbonate chain segments containing rigid groups, and its structural formula is shown in formula I(a); for the polyester-polycarbonate elastomer, the middle soft segment is a polycarbonate chain segment containing long branches, and the two end hard segments are polyester chain segments containing rigid groups, and its structural formula is shown in formula I(b):

[0006]

[0007] The number average molecular weight of the carbon dioxide-based polycarbonate or polyester-polycarbonate elastomer is in the range of 40-120 kg / mol. For the elastomer with the structure of formula I(a), the weight content of the polycarbonate in the two end hard segments in the polymer is 30-70%, and the weight content of the polycarbonate in the middle soft segment in the polymer is 70-30%; for the elastomer with the structure of formula I(b), the weight content of the polyester in the two end hard segments in the polymer is 20-80%, and the weight content of the polycarbonate in the middle soft segment in the polymer is 80-20%.

[0008] A high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite material is composed of 90-98% of carbon dioxide-based polyester-polycarbonate and 2-10% of the carbon dioxide-based polycarbonate or polyester-polycarbonate block structure elastomer described in claim 1 by weight percentage.

[0009] Preferably, the carbon dioxide-based polyester-polycarbonate has the following structure shown in formula II:

[0010]

[0011] Where a≥1, b≥1, c≥1, d≥1, and a, b, c, d are all integers.

[0012] Preferably, the weight content of the polyester in the carbon dioxide-based polyester-polycarbonate in the polymer is 10-70%, and the weight content of the polycarbonate in the polymer is 30-90%.

[0013] A preparation method of a high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate comprises the following steps:

[0014] (1) Treat the carbon dioxide-based polyester-polycarbonate, carbon dioxide-based polycarbonate or polyester-polycarbonate block structure elastomer respectively in a vacuum drying oven at 80 °C for 12-24 h, then put them into a crusher to crush and perform pre-blending;

[0015] (2) Add the pre-blended composition into a torque rheometer or a twin-screw extruder for melt blending;

[0016] (3) Cool the blended composition, and then press it into a sample.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention uses a carbon dioxide-based polycarbonate or polyester-polycarbonate elastomer with a hard-soft-hard triblock structure as a toughening agent to be compounded with a carbon dioxide-based polyester-polycarbonate to obtain a high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite material. The hard segments at both ends of the carbon dioxide-based polycarbonate or polyester-polycarbonate elastomer are respectively polycarbonate or polyester chain segments containing rigid groups. These rigid polycarbonate and polyester chain segments not only have a relatively high glass transition temperature but also have good compatibility with the polyester-polycarbonate, avoiding the occurrence of incompatibility between the two phases during the blending process. The soft segment in the middle of the carbon dioxide-based polycarbonate or polyester-polycarbonate elastomer is a polycarbonate containing long branched chains, which has a very low glass transition temperature and plays a role in buffering stress and toughening. This special hard-soft-hard triblock structure elastomer as a toughening modifier can be used to prepare a high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate. And while effectively improving the toughness and processing performance of the carbon dioxide-based biodegradable polyester-polycarbonate material, it still maintains good tensile strength and light transmittance.

[0019] (2) The carbon dioxide-based polycarbonate or polyester-polycarbonate elastomer toughening and plasticizing agent used in the present invention not only has an excellent toughening effect on the carbon dioxide-based polyester-polycarbonate material at room temperature but can still toughen the carbon dioxide-based polyester-polycarbonate material in an environment below 0°C.

[0020] (3) The carbon dioxide-based polycarbonate or polyester-polycarbonate elastomer prepared in the present invention is non-toxic and is not easy to migrate or leach out. Through a large number of experiments in the present invention, it is found that because the hard segment chains at both ends of the elastomer have very good compatibility with the polyester-polycarbonate substrate, a compatibilizer does not need to be added during processing, thereby greatly reducing the cost of the carbon dioxide-based biodegradable polyester-polycarbonate-based composite material.

[0021] (4) Both the carbon dioxide-based polyester-polycarbonate material and the elastomer material used for toughening in the present invention are synthesized from carbon dioxide, which is green and environmentally friendly; it has complete biodegradability and is an environmentally friendly material. Detailed implementation mode

[0022] Example 1

[0023] The polycarbonate elastomer (the structural formula is as shown in Formula I (a), X2 = CH2OC8H 17, with a hard segment content of 47 wt%, Mn = 70.5 kg / mol) and polyester-polycarbonate particles (structural formula as in formula II(a), X1 = H, X2 = CH3, polyester content of 45 wt%, Mn = 74.3 kg / mol) were placed in a vacuum drying oven at 80 °C and dried for 12 h. Weighed 2.5 g of polycarbonate elastomer and 47.5 g of polyester-polycarbonate particles and put them into a pulverizer, and pre-blended them at room temperature. Then the pre-blended composition was added to a torque rheometer and blended at 160 °C and 70 rpm for 20 min. The obtained mixture was preheated with a flat vulcanizer at 160 °C for 2 minutes, and then hot-pressed for another 4 minutes, and then placed on a cooling plate to cool to room temperature to obtain dumbbell-shaped specimens with a thickness of about 1 mm and rectangular impact specimens with a V-notch and a thickness of about 4 mm. The prepared high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite had a light transmittance of 89%; the tensile strength at room temperature was 34 MPa, the elongation at break was 79%, and the impact strength was 4.5 KJ / m 2 .

[0024] Example 2

[0025] The polycarbonate-based elastomer (structural formula as in formula I(a), X2 = CH2OC8H 17 , with a hard segment content of 47 wt%, Mn = 70.5 kg / mol) and polyester-polycarbonate particles (structural formula as in formula II(a), X1 = H, X2 = CH3, polyester content of 45 wt%, Mn = 74.3 kg / mol) were placed in a vacuum drying oven at 80 °C and dried for 12 h. Weighed 5 g of polycarbonate elastomer and 45 g of polyester-polycarbonate particles and put them into a pulverizer, and pre-blended them at room temperature. Then the pre-blended composition was added to a torque rheometer and blended at 160 °C and 70 rpm for 20 min. The obtained mixture was preheated with a flat vulcanizer at 160 °C for 2 minutes, and then hot-pressed for another 4 minutes, and then placed on a cooling plate to cool to room temperature to obtain dumbbell-shaped specimens with a thickness of about 1 mm and rectangular specimens with a V-notch and a thickness of about 4 mm. The prepared high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite had a light transmittance of 83%; the tensile strength at room temperature was 31 MPa, the elongation at break was 98%, and the impact strength was 4.1 KJ / m 2 .

[0026] Example 3

[0027] Put the polycarbonate elastomer (structural formula as formula Ⅰ(a), X2 = CH2OC2H4SC4H9, hard segment content is 46.4 wt%, Mn = 85.8 kg / mol) and polyester-polycarbonate particles (structural formula as formula Ⅱ(a), X1 = H, X2 = CH3, polyester content is 45 wt%, Mn = 74.3 kg / mol) into a vacuum drying oven at 80 °C and dry for 12 h. Weigh 5 g of polycarbonate elastomer and 45 g of polyester-polycarbonate particles and put them into a pulverizer for pre-blending at room temperature. Then add the pre-blended composition into a torque rheometer and blend at 160 °C and 70 rpm for 20 min. Preheat the obtained mixture at 160 °C for 2 minutes using a flat vulcanizer, and continue hot pressing for 4 minutes. Then put it on a cooling plate and cool to room temperature to obtain dumbbell-shaped specimens about 1 mm thick and rectangular specimens with a V-notch about 4 mm thick. The prepared high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite has a light transmittance of 84%; the tensile strength at room temperature is 31 MPa, the elongation at break is 150%, and the impact strength is 4.4 KJ / m 2 .

[0028] Example 4

[0029] Put the polyester-polycarbonate elastomer (structural formula as formula Ⅰ(b), X2 = CH2OC8H 17 , hard segment content is 29.6 wt%, Mn = 64.9 kg / mo) and polyester-polycarbonate particles (structural formula as formula Ⅱ(a), X1 = H, X2 = CH3, polyester content is 45 wt%, Mn = 74.3 kg / mol) into a vacuum drying oven at 80 °C and dry for 12 h. Weigh 5 g of polycarbonate elastomer and 45 g of polyester-polycarbonate particles and put them into a pulverizer for pre-blending at room temperature. Then add the pre-blended composition into a torque rheometer and blend at 160 °C and 70 rpm for 20 min. Preheat the obtained mixture at 160 °C for 2 minutes using a flat vulcanizer, and continue hot pressing for 4 minutes. Then put it on a cooling plate and cool to room temperature to obtain dumbbell-shaped specimens about 1 mm thick and rectangular specimens with a V-notch about 4 mm thick. The prepared high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite has a light transmittance of 78%; the tensile strength at room temperature is 26 MPa, the elongation at break is 95%, and the impact strength is 3.9 KJ / m 2 .

[0030] Example 5

[0031] Put the polyester-polycarbonate elastomer (structural formula as formula Ⅰ(b), X1 = CH3, X2 = CH2OC2H4SC4H9, hard segment content is 55.4 wt%, Mn = 95.7 kg / mol) and polyester-polycarbonate particles (structural formula as formula Ⅱ(a), X1 = H, X2 = CH3, polyester content is 45 wt%, Mn = 74.3 kg / mol) into a vacuum drying oven at 80 °C and dry for 12 h. Weigh 5 g of the polyester-polycarbonate elastomer and 45 g of the polyester-polycarbonate particles and put them into a pulverizer, and perform pre-blending at room temperature. Then add the pre-blended composition into a torque rheometer and blend at 70 rpm for 20 min under the condition of 160 °C. Preheat the obtained mixture for 2 minutes with a flat vulcanizer at 160 °C, and continue hot pressing for 4 minutes, then put it on a cooling plate and cool to room temperature to obtain dumbbell-shaped specimens about 1 mm thick and rectangular specimens with a V-notch about 4 mm thick. The light transmittance of the prepared high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite material is 85%; the tensile strength at room temperature is 32 MPa, the elongation at break is 154%, and the impact strength is 4.3 KJ / m 2 。

[0032] Example 6

[0033] Put the polyester-polycarbonate elastomer (structural formula as formula Ⅰ(b), X1 = CH3, X2 = CH2OC2H4SC4H9, hard segment content is 55.4 wt%, Mn = 95.7 kg / mol) and polyester-polycarbonate particles (structural formula as formula Ⅱ(b), X1 = Cl, X2 = CH3, polyester content is 30 wt%, Mn = 58.7 kg / mol) into a vacuum drying oven at 80 °C and dry for 12 h. Weigh 5.0 g of the polyester-polycarbonate block-structured elastomer and 45.0 g of the polyester-polycarbonate particles and put them into a pulverizer, and perform pre-blending at room temperature. Then add the pre-blended composition into a torque rheometer and blend at 70 rpm for 20 min under the condition of 160 °C. Preheat the obtained mixture for 2 minutes with a flat vulcanizer at 160 °C, and continue hot pressing for 4 minutes, then put it on a cooling plate and cool to room temperature to obtain dumbbell-shaped specimens about 1 mm thick and rectangular specimens with a V-notch about 4 mm thick. The light transmittance of the prepared high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite material is 82%; the tensile strength at room temperature is 35 MPa, the elongation at break is 104%, and the impact strength is 5.3 KJ / m 2 。

[0034] Comparative Example 1

[0035] The commercial toughening agent MBS and polyester-polycarbonate particles (structural formula as shown in Formula II(a), X1 = H, X2 = CH3, polyester content is 45 wt%, Mn = 74.3 kg / mol) were placed in a vacuum drying oven at 80 °C and dried for 12 h. 5 g of MBS and 45 g of polyester-polycarbonate particles were weighed and put into a pulverizer for pre-blending at room temperature, and then the pre-blended composition was added to a torque rheometer and blended at 70 rpm for 20 min under the condition of 160 °C. The obtained mixture was preheated for 2 minutes with a flat vulcanizer at 160 °C, and then hot-pressed for another 4 minutes, and then cooled to room temperature on a cooling plate to obtain dumbbell-shaped specimens with a thickness of about 1 mm and rectangular specimens with a V-notch and a thickness of about 4 mm. The light transmittance of the toughened and plasticized polyester-polycarbonate obtained was 64%; the tensile strength at room temperature was 35 MPa, the elongation at break was 37%, and the impact strength was 3.1 KJ / m 2 .

Claims

1. A carbon dioxide-based polycarbonate or polyester-polycarbonate elastomer, characterized in that: The elastomer has a hard-soft-hard triblock structure. For polycarbonate-based elastomers, the middle soft segment is a polycarbonate chain segment containing long branched chains, and the two end hard segments are polycarbonate chain segments containing rigid groups, and its structural formula is as shown in Formula I(a); for polyester-polycarbonate-based elastomers, the middle soft segment is a polycarbonate chain segment containing long branched chains, and the two end hard segments are polyester chain segments containing rigid groups, and its structural formula is as shown in Formula I(b):

2. The carbon dioxide-based polycarbonate or polyester-polycarbonate elastomer according to claim 1, characterized in that Its number average molecular weight is in the range of 40-120 kg / mol. Among them, for the elastomer with the structure of Formula I(a), the weight content of the polycarbonate in the two end hard segments in the polymer is 30-70%, and the weight content of the polycarbonate in the middle soft segment in the polymer is 70-30%; for the elastomer with the structure of Formula I(b), the weight content of the polyester in the two end hard segments in the polymer is 20-80%, and the weight content of the polycarbonate in the middle soft segment in the polymer is 80-20%.

3. A high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate composite material, characterized in that It is composed of 90-98% of carbon dioxide-based polyester-polycarbonate and 2-10% of the carbon dioxide-based polycarbonate or polyester-polycarbonate block structure elastomer described in Claim 1 by weight percentage.

4. The high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate according to claim 3, characterized in that The carbon dioxide-based polyester-polycarbonate described has the following structural formula II: Where a≥1, b≥1, c≥1, d≥1, and a, b, c, d are all integers.

5. The high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate according to claim 4, characterized in that The weight content of the polyester in the carbon dioxide-based polyester-polycarbonate in the polymer is 10-70%, and the weight content of the polycarbonate in the polymer is 30-90%.

6. A method for preparing the high-strength and high-toughness carbon dioxide-based biodegradable polyester-polycarbonate as described in claim 3, characterized in that It includes the following steps: (1) Treat the carbon dioxide-based polyester-polycarbonate, carbon dioxide-based polycarbonate or polyester-polycarbonate block structure elastomer respectively in a vacuum drying oven at 80°C for 12-24 h, then put them into a crusher to crush and conduct pre-blending; (2) Add the pre-blended composition into a torque rheometer or a twin-screw extruder for melt blending; (3) Cool the blended composition, and then press it into a sample.

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