Biodegradable polyester material as well as preparation method and application thereof

Abstract

The invention relates to a biodegradable polyester material as well as a preparation method and application thereof, and belongs to the technical field of compositions of high-molecular compounds. The biodegradable polyester material disclosed by the invention is prepared from the following components in parts by weight: 40 to 60 parts of biodegradable polyester, 30 to 45 parts of starch stearate, 5 to 15 parts of a plasticizer, 0.2 to 1.5 parts of an anhydride compound, 0.5 to 1.5 parts of an anti-hydrolysis agent and 0 to 2 parts of a processing aid, the biodegradable polyester is prepared from PBAT resin; the molar ratio of the structural units derived from terephthalic acid is greater than or equal to 49% based on the total molar weight of the structural units derived from terephthalic acid and adipic acid in the PBAT resin. The biodegradable polyester material has good mechanical properties and excellent damp-heat aging resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer compound, in particular to a biodegradable polyester material and a preparation method and application thereof. BACKGROUND

[0002] Plastic films are widely used in food packaging, electronic product packaging, supermarket shopping bags, garbage bags or express bags and other fields, but traditional plastic films are difficult to decompose in the natural environment, which can easily lead to a large amount of solid waste accumulation and affect the ecological environment. Compared with traditional plastic films, biodegradable plastic films can be decomposed by microorganisms into water, carbon dioxide and biomass under suitable conditions, which can effectively reduce the pollution to the environment. Polybutylene adipate terephthalate (PBAT) is a thermoplastic biodegradable material, but it cannot be used alone, and is usually blended with other biodegradable materials (such as polylactic acid) for modification and filled with additives such as starch to form a composite material before application. However, it is found in actual application that the PBAT composite material is prone to degradation in a humid and hot environment, which can quickly reduce its mechanical properties, and it is difficult to meet the application requirements under humid and hot conditions. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a biodegradable polyester material and a preparation method and application thereof.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: In a first aspect, the present application provides a biodegradable polyester material, which comprises the following components by weight fraction: biodegradable polyester 40-60 parts, stearic acid starch ester 30-45 parts, plasticizer 5-15 parts, acid anhydride compound 0.2-1.5 parts, anti-hydrolysis agent 0.5-1.5 parts, and processing aid 0-2 parts. The biodegradable polyester comprises PBAT resin. Based on the total mole amount of structural units derived from terephthalic acid and adipic acid in the PBAT resin, the mole proportion of the structural units derived from terephthalic acid is ≥49%.

[0005] The present application uses a specific PBAT resin as the main component of the biodegradable polyester, and cooperates with stearic acid starch ester and anti-hydrolysis agent to improve the wet heat aging resistance of the biodegradable polyester material through synergistic effect. At the same time, the stearic acid starch ester is combined with the plasticizer and the acid anhydride compound to improve the plasticizing performance of the stearic acid starch ester through synergistic effect, so that the biodegradable polyester material has good mechanical properties.

[0006] The mass percentage of the biodegradable polyester in the biodegradable polyester material is greater than or equal to 35%, and the mass percentage of the stearin in the biodegradable polyester material is greater than or equal to 25%. The PBAT resin is the main component of the biodegradable polyester, and the mass percentage of the PBAT resin in the biodegradable polyester is greater than or equal to 60%.

[0007] In some embodiments, the weight percentage of the biodegradable polyester in the biodegradable polyester material can be, but is not limited to, 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, or 60 parts, or within a range defined by any two of the above values.

[0008] In some embodiments, the weight percentage of the stearin in the biodegradable polyester material can be, but is not limited to, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, or 45 parts, or within a range defined by any two of the above values.

[0009] In some embodiments, the weight percentage of the plasticizer in the biodegradable polyester material can be, but is not limited to, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, 13 parts, 13.5 parts, 14 parts, 14.5 parts, or 15 parts, or within a range defined by any two of the above values.

[0010] In some embodiments, the weight percentage of the anhydride compound in the biodegradable polyester material can be, but is not limited to, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, or 1.5 parts, or within a range defined by any two of the above values.

[0011] In some embodiments, the weight percentage of the anti-hydrolysis agent in the biodegradable polyester material can be, but is not limited to, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, or 1.5 parts, or within a range defined by any two of the above values.

[0012] In some embodiments, the weight fraction of the processing aid in the biodegradable polyester material can be, but is not limited to, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, 1.1 part, 1.2 part, 1.3 part, 1.4 part, 1.5 part, 1.6 part, 1.7 part, 1.8 part, 1.9 part, or 2 part, or within a range between any two of the above values.

[0013] As a preferred embodiment of the biodegradable polyester material of the present application, the PBAT resin has a melt mass-flow rate of 1.5 g / 10 min to 10 g / 10 min at 190 °C, 2.16 kg (ISO 1133-2011 standard), which can be, but is not limited to, 1.5 g / 10 min, 2 g / 10 min, 2.5 g / 10 min, 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min, 5.5 g / 10 min, 6 g / 10 min, 6.5 g / 10 min, 7 g / 10 min, 7.5 g / 10 min, 8 g / 10 min, 8.5 g / 10 min, 9 g / 10 min, 9.5 g / 10 min, or 10 g / 10 min, or within a range between any two of the above values.

[0014] As a preferred embodiment of the biodegradable polyester material of the present application, the PBAT resin has a mole ratio of the structural unit derived from terephthalic acid to the total mole amount of the structural units derived from terephthalic acid and adipic acid in the PBAT resin of 50% to 53%, which can be, but is not limited to, 50%, 50.5%, 51%, 51.5%, 52%, 52.5%, or 53%, or within a range between any two of the above values.

[0015] As a preferred embodiment of the biodegradable polyester material of the present application, the degree of substitution of the stearic acid starch ester is 0.01 to 0.3, which can be, but is not limited to, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, or 0.3, or within a range between any two of the above values.

[0016] The degree of substitution of the stearic acid starch ester can be determined by acid-base titration method. For details, please refer to Du Siqi, Wang Xiaofeng, Zhang Yifan, et al. Preparation of stearic acid starch ester and stability of pickering emulsion [J]. Food Industry Science and Technology, 2023, 44(9): 1-9.

[0017] As a preferred embodiment of the biodegradable polyester material of the present application, the biodegradable polyester further comprises at least one of a PLA resin and a PBST resin; preferably, the biodegradable polyester further comprises a PLA resin, which is beneficial to improve the tensile strength of the biodegradable polyester material, and improve the stiffness of the film and the lifting performance of the film bag product.

[0018] In some embodiments, the PLA (polylactic acid) resin comprises at least one of PLLA, PDLA, and PLLA / PDLA copolymer, preferably PLLA / PDLA copolymer.

[0019] As a preferred embodiment of the biodegradable polyester material of the present application, the PBST resin has a melt mass flow rate of 1.5 g / 10 min to 10 g / 10 min at 190°C and 2.16 kg (ISO 1133-2011 standard), for example, but not limited to, 1.5 g / 10 min, 2 g / 10 min, 2.5 g / 10 min, 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min, 5.5 g / 10 min, 6 g / 10 min, 6.5 g / 10 min, 7 g / 10 min, 7.5 g / 10 min, 8 g / 10 min, 8.5 g / 10 min, 9 g / 10 min, 9.5 g / 10 min, or 10 g / 10 min, or within a range between any two of the above values.

[0020] As a preferred embodiment of the biodegradable polyester material of the present application, based on the total number of moles of structural units derived from terephthalic acid and succinic acid in the PBST resin, the mole percentage of the structural units derived from terephthalic acid is 44% to 50%, for example, but not limited to, 44%, 44.5%, 45%, 45.5%, 46%, 46.5%, 47%, 47.5%, 48%, 48.5%, 49%, 49.5%, or 50%, or within a range between any two of the above values.

[0021] As a preferred embodiment of the biodegradable polyester material of the present application, the anti-hydrolysis agent comprises, but is not limited to, at least one of a carbodiimide anti-hydrolysis agent and an oxazoline anti-hydrolysis agent.

[0022] As a preferred embodiment of the biodegradable polyester material of the present application, at least one of the following conditions is satisfied: (1) the plasticizer comprises at least one of water, glycerol, sorbitol, polyglycerol; (2) the acid anhydride compound comprises at least one of acetic anhydride, maleic anhydride, succinic anhydride; (3) the processing aid comprises at least one of opening agent, slip agent, antioxidant, weather resistant agent, antistatic agent.

[0023] In some embodiments, the opening agent comprises, but is not limited to, at least one of talc, calcium carbonate, and silicon dioxide.

[0024] In some embodiments, the slip agent comprises, but is not limited to, at least one of erucic acid amide, oleic acid amide, and stearic acid amide.

[0025] In some embodiments, the antioxidant comprises, but is not limited to, at least one of hindered phenolic antioxidant, phosphite antioxidant, and sulfide antioxidant.

[0026] In some embodiments, the weather resistant agent comprises, but is not limited to, at least one of hindered amine light stabilizer and ultraviolet absorber.

[0027] In some embodiments, the antistatic agent comprises, but is not limited to, at least one of monoglyceride antistatic agent and alkyl ethoxy amine antistatic agent.

[0028] In a second aspect, the present application provides a preparation method of the biodegradable polyester material, comprising the following steps: uniformly mixing the components and then melt extruding to obtain the biodegradable polyester material.

[0029] Optionally, in the preparation method, a twin-screw extruder can be used for melt extrusion, the temperature for melt extrusion is 120-180℃, and the screw rotation speed of the twin-screw extruder is 200-400 rpm.

[0030] In a third aspect, the present application provides an application of the biodegradable polyester material in preparing a biodegradable film.

[0031] In a fourth aspect, the present application provides a film made of the biodegradable polyester material.

[0032] Exemplarily, the film can be used for fruit and vegetable bags, bread / pastry bags, meat tray coating films, meal box sealing films, disposable tableware packaging bags, tea bag / coffee capsule packaging bags, beverage cup sealing films, garbage bags, shopping bags, express delivery bags, document bags, flower packaging, etc.

[0033] Compared with the prior art, the present application has the following beneficial effects: This invention uses a specific PBAT resin as the main component of biodegradable polyester, combined with stearic acid starch ester and an anti-hydrolysis agent. The three work synergistically to improve the resistance of biodegradable polyester materials to humid heat aging. At the same time, stearic acid starch ester, combined with plasticizers and acid anhydride compounds, can work synergistically to improve the plasticizing properties of stearic acid starch ester, thereby enabling biodegradable polyester materials to have good mechanical properties. Detailed Implementation

[0034] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0035] Unless otherwise specified, all other materials, reagents, etc. used in the examples and comparative examples are commercially available.

[0036] 1. Raw materials and reagents 1) PBAT resin PBAT resin is prepared by the following method: terephthalic acid, adipic acid, and 1,4-butanediol (in excess) are reacted at 235°C and 75 Pa to obtain a first product (T1). The first product is then reacted at 240°C and 1200 Pa to obtain a pre-condensation product (T2). Finally, the product is reacted at 245°C and 150 Pa to obtain different PBAT resins (T3). The total amount of terephthalic acid and adipic acid is in a molar ratio of 1,4-butanediol to 1:1.4. The melt flow rate of PBAT resin was controlled by adjusting T1, T2, and T3. The melt flow rate of PBAT resin was measured according to ISO 1133-2011 standard at 190℃ and 2.16kg, as shown in Table 1.

[0037] Table 1 PBAT Resin The “T content” in Table 1 represents the total molar amount of structural units derived from terephthalic acid and adipic acid in PBAT resin, where the molar percentage of structural units derived from terephthalic acid is; this can be achieved by keeping the total amount of terephthalic acid and adipic acid constant and adjusting the molar percentage of terephthalic acid.

[0038] 2) Stearic acid starch ester and phosphate starch Stearic acid starch ester 1, with a degree of substitution of 0.25; Stearic acid starch ester 1 was prepared by the following method: starch (corn starch, purchased from Shandong Jinyumi) was dried in a fluidized bed (moisture content controlled at ≤3%), and the esterifying agent stearic anhydride, the catalyst anhydrous sodium carbonate, and the dried starch were mixed evenly in a high-efficiency mixer. The mixture was reacted in a reactor at 150±10℃ for 3.5±0.5h. The material was then rapidly cooled to below 60℃, washed, dried, pulverized, and sieved to obtain stearic acid starch ester 1.

[0039] Stearic acid starch ester 2, with a degree of substitution of 0.03; Stearic acid starch ester 2 was prepared by the following method: starch (cassava starch, purchased from Thai Hoa, Vietnam) was dried using a fluidized bed (moisture content controlled at ≤3%), and the esterifying agent stearic acid, the catalyst anhydrous sodium carbonate, and the dried starch were mixed evenly using a high-efficiency mixer. The mixture was reacted in a reactor at 150±10℃ for 1.5±0.5h, and then the material was rapidly cooled to below 60℃. After washing, drying, pulverizing, and sieving, stearic acid starch ester 2 was obtained.

[0040] Phosphate starch with a degree of substitution of 0.034 was prepared according to existing technology (Bi Yanli, Zhang Hongwei. Semi-dry synthesis process and performance study of phosphate starch [J]. Grain and Feed Industry, No. 11, 2008). The specific preparation conditions are as described in the process parameters in the abstract. The starch used was cassava starch, purchased from Thai Hua, Vietnam.

[0041] 3) Plasticizers Plasticizer 1 is glycerin, commercially available; Plasticizer 2 is sorbitol, which is commercially available.

[0042] 4) Acid anhydrides Acid anhydride compound 1 is acetic anhydride, which is commercially available; Compound 2 is maleic anhydride, which is commercially available.

[0043] 5) Anti-hydrolysis agent Anti-hydrolysis agent 1 is a polymeric carbodiimide, brand name HyMax 210, manufacturer Langyi Technology; Anti-hydrolysis agent 2 is a monomeric carbodiimide, brand name HyMax 1010, manufactured by Langyi Technology.

[0044] 6) Processing aids Processing aid 1 is an opening agent (talc), brand name TYT-777A, manufactured by Haicheng Tianyuan Chemical. Processing aid 2 is a slip agent (erucamide), brand name ER-CH-MB-(SI), manufacturer: Croda.

[0045] 2. Preparation method of the biodegradable polyester material of the present invention According to the formula, the components are mixed evenly and then added to a twin-screw extruder. The mixture is melt-extruded and granulated at 120°C to 180°C to obtain a biodegradable polyester material. The screw speed of the twin-screw extruder is 300 rpm.

[0046] Table 2 shows the weight parts of each component in the biodegradable polyester materials of Examples 1 to 10. Table 3 shows the weight parts of each component in the biodegradable polyester materials of Comparative Examples 1 to 4. In Tables 2 and 3, " / " indicates that there are no relevant parameters.

[0047] 3. Performance Testing The biodegradable polyester materials in each embodiment and comparative example were dried and the moisture content was controlled to be less than 500 ppm. Then, they were blown into a film to obtain a biodegradable film. The blown film temperature was 130°C to 160°C, the blown film die diameter was 70 mm, the blow-up ratio was 3.0, and the resulting biodegradable film had a perimeter of 660 mm and a thickness of 20 μm.

[0048] 1) Tensile strength and elongation at break test The biodegradable membrane was tested for longitudinal tensile strength and elongation at break, and transverse tensile strength and elongation at break according to GB / T 1040.3-2006 standard, with a tensile rate of 500 mm / min.

[0049] 2) Damp heat aging test The biodegradable membrane was placed at a temperature of 60°C and a humidity of 60%RH, and the time required for its transverse elongation to decrease by 50% under these conditions was tested to evaluate its resistance to damp heat aging.

[0050] Table 4. Performance of biodegradable polyester materials in each example and comparative example. According to the data in Table 4, the transverse tensile strength of the biodegradable polyester materials in Examples 1 to 10 all reached above 17 MPa and the elongation at break all reached above 300%, while the longitudinal tensile strength all reached above 11 MPa and the elongation at break all reached above 400%. Furthermore, the time required for the transverse elongation at break to decrease by 50% was greater than or equal to 5.5 days, indicating that the biodegradable polyester material of the present invention possesses both good mechanical properties and excellent resistance to humid heat aging. Meanwhile, according to Comparative Examples 1 to 3, when the T content in the PBAT resin is too low, or when phosphate starch or unmodified corn starch is used to replace stearic acid starch ester, although the initial mechanical properties of the biodegradable polyester material are only slightly affected, the resistance to humid heat aging cannot be effectively improved, leading to a rapid decline in its mechanical properties and failure in humid heat environments. Comparative Example 4 also shows that removing acid anhydride compounds from the biodegradable polyester material results in a significant decrease in its mechanical properties.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A biodegradable polyester material, characterized in that, By weight, it includes the following components: The ingredients are: 40-60 parts biodegradable polyester, 30-45 parts stearic acid starch ester, 5-15 parts plasticizer, 0.2-1.5 parts acid anhydride compound, 0.5-1.5 parts anti-hydrolysis agent, and 0-2 parts processing aid. The biodegradable polyester includes PBAT resin; Based on the total molar amount of structural units derived from terephthalic acid and adipic acid in the PBAT resin, the molar percentage of the structural units derived from terephthalic acid is ≥49%.

2. The biodegradable polyester material as described in claim 1, characterized in that, The PBAT resin has a melt flow rate of 1.5 g / 10 min to 10 g / 10 min at 190 °C and 2.16 kg. And / or, based on the total molar amount of structural units derived from terephthalic acid and adipic acid in the PBAT resin, the molar percentage of the structural units derived from terephthalic acid is 50% to 53%.

3. The biodegradable polyester material as described in claim 1, characterized in that, The degree of substitution of the stearic acid starch ester is from 0.01 to 0.

3.

4. The biodegradable polyester material as described in claim 1, characterized in that, The biodegradable polyester also includes at least one of PLA resin and PBST resin.

5. The biodegradable polyester material as described in claim 4, characterized in that, The PBST resin has a melt flow rate of 1.5 g / 10 min to 10 g / 10 min at 190 °C and 2.16 kg.

6. The biodegradable polyester material as described in claim 4, characterized in that, Based on the total molar amount of structural units derived from terephthalic acid and succinic acid in the PBST resin, the molar percentage of the structural units derived from terephthalic acid is 44% to 50%.

7. The biodegradable polyester material according to any one of claims 1 to 6, characterized in that, At least one of the following conditions must be met: (1) The plasticizer includes at least one of water, glycerin, sorbitol, and polyglycerol; (2) The acid anhydride compounds include at least one of acetic anhydride, maleic anhydride, and succinic anhydride; (3) The processing aids include at least one of the following: opening agent, slip agent, antioxidant, weathering agent, and antistatic agent.

8. A method for preparing the biodegradable polyester material according to any one of claims 1 to 7, characterized in that, The process includes the following steps: mixing the components evenly and then melting and extruding them to obtain a biodegradable polyester material.

9. The application of the biodegradable polyester material according to any one of claims 1 to 7 in the preparation of biodegradable membranes.

10. A thin film, characterized in that, Made from the biodegradable polyester material as described in any one of claims 1 to 7.

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