Biodegradable composition as well as preparation method and application thereof

Abstract

The invention relates to a biodegradable composition as well as a preparation method and application thereof, and belongs to the technical field of compositions of high-molecular compounds. The biodegradable composition disclosed by the invention is prepared from the following components in parts by weight: 44 to 90 parts of PBAT resin, 5 to 15 parts of amorphous resin and 5 to 40 parts of inorganic filler, based on the total molar weight of a terephthalic acid monomer unit and an adipic acid monomer unit in the PBAT resin, the molar ratio of the terephthalic acid monomer unit is 47-49%; the amorphous resin is at least one of PPC-P, PMMA (Polymethyl Methacrylate), PETG (Polyethylene Terephthalate Glycol) and PCTG; the inorganic filler comprises at least one of calcium carbonate and talcum powder; the particle size D50 of the calcium carbonate is less than 5 [mu] m, and / or the particle size D50 of the talcum powder is less than 8 [mu] m. The biodegradable film produced by adopting the biodegradable composition under a low blow-up ratio process has excellent dart falling performance, and can meet the requirement of ultra-long shelf life.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer compound compositions, and in particular to a biodegradable composition and a preparation method and application thereof. Background Art

[0002] Polybutylene adipate terephthalate (PBAT) is a resin copolymerized by a rigid aromatic chain (butylene terephthalate) and a flexible fatty chain (butylene adipate), which can be degraded into water and carbon dioxide by microorganisms and can replace traditional plastics for the production of packaging materials, medical products or films. However, there are still many problems in the actual use of PBAT-based biodegradable films. For example, compared with high blow-up ratios, the initial dart drop performance of films produced at low blow-up ratios is lower, and the performance decay rate during the shelf life is faster, which can easily lead to a significant decrease in the dart drop performance of the film after being placed for a period of time, making it difficult to meet the use requirements of film bags in specific scenarios. Taking milk tea bags or agricultural mulch films as an example, their actual use needs to be produced at a lower blow-up ratio, and their performance decay during the use cycle should not be too fast; especially for agricultural mulch films, if their performance decays too quickly, it is easy to cause defects such as holes in the period when crops need to be protected, thereby causing the agricultural mulch films to lose their functions of heat preservation and moisture retention, directly leading to reduced crop yields.

[0003] The study found that the performance decay of PBAT-based biodegradable films during the shelf life is not only related to the natural aging molecular chain breakage of PBAT under different environmental conditions, but also to the initial state of the aggregated structure and the change over time under different processing conditions, and the change of the condensed structure has a more obvious effect; PBAT itself is a semi-crystalline material, which crystallizes slowly and has low crystallinity, and its glass transition temperature is about -30°C. It is a slow recrystallization process at room temperature or ambient temperature. The longitudinal orientation of the film is more obvious under low blow-up ratio, and the orientation has a greater impact on recrystallization. The toughness of the material decreases after recrystallization, resulting in poor dart drop performance of PBAT-based biodegradable films. At present, the prior art generally improves the dart drop performance of PBAT-based biodegradable films by adding rigid polylactic acid (PLA) to PBAT, but due to the weak interface interaction between PLA and PBAT, and PLA itself is also a semi-crystalline material, its own recrystallization will also reduce its toughness, resulting in poor dart drop performance of PBAT-based biodegradable films. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a biodegradable composition and a preparation method and application thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a biodegradable composition, comprising the following components by weight: 44 to 90 parts of PBAT resin, 5 to 15 parts of amorphous resin, and 5 to 40 parts of inorganic filler;

[0007] Based on the total molar amount of the terephthalic acid monomer unit and the adipic acid monomer unit in the PBAT resin, the molar proportion of the terephthalic acid monomer unit is 47% to 49%;

[0008] The amorphous resin is at least one of PPC-P, PMMA, PETG, and PCTG;

[0009] The inorganic filler includes at least one of calcium carbonate and talc;

[0010] The particle size D of the calcium carbonate 50 <5μm; and / or, the particle size D of the talc 50 <8μm.

[0011] The present invention adjusts the molar ratio of terephthalic acid monomer units in PBAT resin and combines it with a specific amorphous resin. The amorphous resin and PBAT resin have good interface interaction, which can improve the rigidity and toughness balance of the biodegradable composition. At the same time, with inorganic fillers of specific particle size, the three work together to improve the dart drop performance of the biodegradable composition, so that the performance of the biodegradable film prepared at a low blow-up ratio (≤2.0) decays slowly, thereby having an excellent long shelf life. At the same time, if the particle size of the inorganic filler is too large, the interface defects between it and the resin will be larger, resulting in poor performance of the biodegradable composition.

[0012] It should be noted that PPC-P refers to polypropylene carbonate-phthalate, PMMA refers to polymethyl methacrylate, PETG refers to polyethylene terephthalate-1,4-cyclohexane dimethanol with CHDM < 50%, and PCTG refers to polyethylene terephthalate-1,4-cyclohexane dimethanol with CHDM > 50%. In addition, the PBAT resin in the above-mentioned biodegradable composition is a base resin, and its mass percentage is ≥ 40%.

[0013] The molar content of the terephthalic acid monomer unit and the adipic acid monomer unit in the above PBAT resin can be obtained by nuclear magnetic resonance testing, and the molar proportion of the terephthalic acid monomer unit (%) = the molar content of the terephthalic acid monomer unit / (the molar content of the terephthalic acid monomer unit + the molar content of the adipic acid monomer unit) × 100%.

[0014] Optionally, the PPC-P adopts ISO 1133-2011 standard, and the melt mass flow rate at 190° C. and 2.16 kg is 2 to 40 g / 10 min, specifically, it can be any one of 2 g / 10 min, 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, or any two of the range values;

[0015] The PMMA adopts ISO 1133-2011 standard, and the melt mass flow rate at 230° C. and 3.8 kg is 2 to 20 g / 10 min, and specifically can be any one of 2 g / 10 min, 4 g / 10 min, 6 g / 10 min, 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, 14 g / 10 min, 16 g / 10 min, 18 g / 10 min, and 20 g / 10 min, or any two of the range values;

[0016] The PETG adopts ISO 1133-2011 standard, and the melt mass flow rate at 250° C. and 2.16 kg is 5 to 40 g / 10 min, and specifically can be any one of 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 35 g / 10 min, and 40 g / 10 min, or any two of the range values;

[0017] The PCTG adopts ISO 1133-2011 standard, and the melt mass flow rate at 280° C. and 2.16 kg is 10 to 60 g / 10 min; specifically, it can be any one of 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, 45 g / 10 min, 50 g / 10 min, 55 g / 10 min, and 60 g / 10 min, or any two of the range values.

[0018] Optionally, the weight proportion of PBAT resin in the above-mentioned biodegradable composition can be 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, and 90 parts; the weight proportion of amorphous resin can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, and 15 parts; the weight proportion of inorganic filler can be 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, and 40 parts.

[0019] As a preferred embodiment of the biodegradable composition of the present invention, the biodegradable composition comprises the following components in parts by weight: 52.5 to 66.5 parts of PBAT resin, 8 to 12 parts of amorphous resin, and 25 to 35 parts of inorganic filler.

[0020] As a preferred embodiment of the biodegradable composition of the present invention, the particle size D of the calcium carbonate is 50 Optionally, the particle size D of the calcium carbonate is 50 Specifically, the value may be any one of or any two of the ranges of 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.3 μm, 2.5 μm, 2.8 μm, and 3 μm.

[0021] As a preferred embodiment of the biodegradable composition of the present invention, the particle size D of the talc powder is 50 Optionally, the particle size D of the talcum powder is 0.5 to 6 μm. 50 Specifically, the value may be any one of or any two of the ranges of 0.5 μm, 0.7 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, and 6 μm.

[0022] The study found that using calcium carbonate or talc with the above particle size as an inorganic filler is not only conducive to uniform dispersion of the inorganic filler in the biodegradable composition to obtain a better opening effect, but also can effectively reduce interface defects with the resin, thereby improving the dart drop performance of the biodegradable composition.

[0023] As a preferred embodiment of the biodegradable composition of the present invention, the PBAT resin adopts ISO1133-2011 standard, and the melt mass flow rate at 190° C. and 2.16 kg is 2 to 10 g / 10 min, preferably 3 to 5 g / 10 min.

[0024] Optionally, the melt mass flow rate of the PBAT resin can be 2g / 10min, 2.5g / 10min, 3g / 10min, 3.5g / 10min, 4g / 10min, 4.5g / 10min, 5g / 10min, 5.5g / 10min, 6g / 10min, 6.5g / 10min, 7g / 10min, 7.5g / 10min, 8g / 10min, 8.5g / 10min, 9g / 10min, 9.5g / 10min, 10g / 10min, or any two of the range values. Studies have found that the PBAT resin with the above melt mass flow rate can make the biodegradable composition have a suitable melt strength, which is beneficial to improve the stability of the blown film.

[0025] As a preferred embodiment of the biodegradable composition of the present invention, the components of the biodegradable composition further include 0 to 1 parts by weight of a lubricant.

[0026] As a preferred embodiment of the biodegradable composition of the present invention, the lubricant includes at least one of erucamide, oleamide, monoglycoside ester, N,N'-ethylene bisstearamide, Fischer-Tropsch wax, pentaerythritol stearate, fatty acid amide and stearic acid.

[0027] In a second aspect, the present invention provides a method for preparing the above-mentioned biodegradable composition, comprising the following steps: mixing the components uniformly and then melt-extruding to obtain the biodegradable composition.

[0028] Optionally, in the above preparation method, a twin-screw extruder can be used for melt extrusion, the temperature of the melt extrusion is 160-200° C., and the screw speed of the twin-screw extruder is 250-350 rpm.

[0029] In a third aspect, the present invention provides use of the above biodegradable composition in preparing a biodegradable film.

[0030] In a fourth aspect, the present invention provides a food packaging bag, a shopping bag or an agricultural mulch film, which is made of the above-mentioned biodegradable composition.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention adjusts the molar ratio of terephthalic acid monomer units in PBAT resin and combines it with a specific amorphous resin. The amorphous resin and PBAT resin have good interface interaction, which can improve the rigidity and toughness balance of the biodegradable composition. At the same time, an inorganic filler with a specific particle size is matched, and the three work synergistically to improve the dart drop performance of the biodegradable composition, so that the performance of the biodegradable film prepared at a low blowing ratio decays slowly, the initial dart drop impact is ≥200g, and the dart drop impact after double 60 aging for 15 days is ≥80g, and the retention rate reaches more than 40%, that is, it has an excellent long shelf life. DETAILED DESCRIPTION

[0033] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0034] Unless otherwise specified, other materials, reagents, etc. used in the examples and comparative examples can be obtained from commercial sources.

[0035] 1. Raw materials and reagents

[0036] 1) PBAT resin

[0037] PBAT resin 1, based on the total molar amount of terephthalic acid monomer units and adipic acid monomer units, wherein the molar proportion of terephthalic acid monomer units is 48%;

[0038] PBAT resin 2, based on the total molar amount of terephthalic acid monomer units and adipic acid monomer units, wherein the molar proportion of terephthalic acid monomer units is 47%;

[0039] PBAT resin 3, based on the total molar amount of terephthalic acid monomer units and adipic acid monomer units, wherein the molar proportion of terephthalic acid monomer units is 49%;

[0040] PBAT resin 4, based on the total molar amount of terephthalic acid monomer units and adipic acid monomer units, wherein the molar proportion of terephthalic acid monomer units is 45%;

[0041] PBAT resin 5, based on the total molar amount of terephthalic acid monomer units and adipic acid monomer units, wherein the molar proportion of terephthalic acid monomer units is 51%;

[0042] Test of the molar content of terephthalic acid (a1) and adipic acid (a2) in PBAT polyester:

[0043] Take 20 mg of PBAT polyester sample and dissolve it in 0.6 mL of deuterated chloroform, and then use Bruker AV 500 NMR spectrometer to measure at room temperature. 1HNMR, calibrated at chloroform solvent peak around 7.26 ppm.

[0044] References: Chen, X.; Chen, W.; Zhu, G.; Huang, F.; Zhang, J., Synthesis, 1H-NMR characterization, and biodegradation behavior of aliphatic-aromatic random copolyester. J. Appl. Polym. Sci. 2007, 104(4): 2643-2649. It can be seen that the four hydrogen atoms on the benzene ring in the terephthalic acid repeating unit appear at around 8.10 ppm; the two CH atoms adjacent to the carbonyl group in the adipic acid repeating unit 2 The 4 hydrogen atoms of the unit appear near 2.33 ppm. Thus, the molar content of the diacid component can be expressed by the integrated areas (IT and IA) of the two peaks at 8.10 ppm and 2.33 ppm:

[0045] The molar content of aromatic dicarboxylic acid in PBAT polyester = IT / (IT+IA)×100%;

[0046] The molar content of adipic acid in PBAT polyester = IA / (IT+IA)×100%.

[0047] The above PBAT resins 1 to 5 are all prepared by the following preparation method: corresponding contents of terephthalic acid, adipic acid, 1,4-butanediol, and glycerol (in an amount of 500 ppm) are added to a reaction kettle, stirred at 190°C for 3 hours, and then tetrabutyl titanate is added as a catalyst, and the temperature is raised to 240°C for reaction for 8 hours to obtain PBAT resin. In the preparation process of the above PBAT resin, the molar ratio of the dibasic acid to the diol is 1:1.4, and the above PBAT resins 1 to 5 are obtained by controlling the molar ratio of terephthalic acid and adipic acid in the dibasic acid.

[0048] Table 1 PBAT resins 1 to 5

[0049] PBAT resin Melt flow rate PBAT resin 1 4.0g / 10min PBAT resin 2 3.8g / 10min PBAT resin 3 3.9g / 10min PBAT resin 4 3.8g / 10min PBAT resin 5 3.9g / 10min

[0050] 2) Amorphous resin, PLA resin

[0051] Amorphous resin 1 (PPC-P resin), manufacturer: Beijing Xuyang, brand: PPC-X 103;

[0052] Amorphous resin 2 (PMMA resin), manufacturer Mitsubishi Chemical, brand PMMA VH5001;

[0053] Amorphous resin 3 (PETG resin), manufacturer Hubei Guoxin, brand PETG 702;

[0054] Amorphous resin 4 (PCTG resin), manufacturer: SK, South Korea, brand: YF 300;

[0055] PLA resin, manufacturer: Kingfa Biotechnology, brand: KB600 NF10.

[0056] 3) Inorganic fillers

[0057] Calcium carbonate 1, particle size D 50 2μm, manufacturer: Switzerland Omya, brand: Omyacarb 1T-CU;

[0058] Calcium carbonate 2, particle size D 50 1.2μm, manufacturer Qingyuan Xinrong, brand ACC-812;

[0059] Calcium carbonate 3, particle size D 50 5μm, manufacturer: Switzerland Omya, brand: Omyacarb 5T-JI;

[0060] Talc 1, particle size D 50 4.5μm, manufacturer Liaoning Xinda, brand SDC-F7;

[0061] Talc 2, particle size D 50 0.7μm, manufacturer Liaoning Aihaiyimi, brand HTPultra5 L;

[0062] Talc 3, particle size D 50 8μm, manufacturer Liaoning Xinda, brand AH-1250N6.

[0063] 4) Lubricant

[0064] Lubricant 1 (erucic acid amide), manufacturer: Crodamide, UK, brand: Crodamide ER-CH-BE-(SI);

[0065] Lubricant 2 (stearic acid), manufacturer: Sven, Indonesia, brand name: SA-1801.

[0066] 2. Preparation method of the biodegradable composition of the present invention

[0067] According to the formula, the components are mixed evenly and then added into a twin-screw extruder, melt-extruded and granulated at 160-200° C. to obtain a biodegradable composition; wherein the screw speed of the twin-screw extruder is 250-350 rpm / min.

[0068] Table 2 Weight parts of each component of the biodegradable composition in Examples 1 to 15

[0069] Example 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 PBAT resin 1 59.5 / / 59.5 59.5 59.5 59.5 59.5 59.5 59.5 59.5 66.5 52.5 90 44 PBAT resin 2 / 59.5 / / / / / / / / / / / / / PBAT resin 3 / / 59.5 / / / / / / / / / / / / Amorphous resin 1 10 10 10 / / / 10 10 10 10 10 8 12 5 15 Amorphous resin 2 / / / 10 / / / / / / / / / / / Amorphous resin 3 / / / / 10 / / / / / / / / / / Amorphous resin 4 / / / / / 10 / / / / / / / / / Calcium carbonate 1 30 30 30 30 30 30 / / / 15 30 25 35 5 40 Calcium carbonate 2 / / / / / / 30 / / / / / / / / Talc 1 / / / / / / / 30 / 15 / / / / / Talc 2 / / / / / / / / 30 / / / / / / Lubricant 1 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 / 0.5 0.5 / 1 Lubricant 2 / / / / / / / / / / 0.5 / / / /

[0070] Table 3 Weight parts of each component of the biodegradable composition in Comparative Examples 1 to 6

[0071] Comparative Example 1 2 3 4 5 6 PBAT resin 1 / / 59.5 59.5 59.5 59.5 PBAT resin 4 59.5 / / / / / PBAT resin 5 / 59.5 / / / / Amorphous resin 1 10 10 / 10 10 2 PLA resin / / 10 / / 8 Calcium carbonate 1 30 30 30 / / 30 Calcium carbonate 3 / / / 30 / / Talc 3 / / / / 30 / Lubricant 1 0.5 0.5 0.5 0.5 0.5 0.5

[0072] 3. Performance testing

[0073] The biodegradable compositions in the embodiments and comparative examples were dried and the moisture content was controlled within 500 ppm, and then subjected to film blowing treatment to obtain a biodegradable film; wherein the film blowing treatment temperature was 130-160° C., the film blowing machine die diameter was 70 mm, the blowing ratio was 2.0, and the obtained biodegradable film had a circumference of 440 mm and a thickness of 25 μm.

[0074] The biodegradable film prepared above was tested as follows:

[0075] 1) Initial dart drop test: Use method A in GB / T 9639.1-2008.

[0076] 2) Dart drop test after double 60 aging for 15 days: The film bag was aged for 15 days at 60°C / 60RH%, then taken out and tested according to method A in GB / T 9639.1-2008.

[0077] Retention rate (%) = initial dart impact / dart impact after double 60 aging for 15 days × 100%.

[0078] Table 4 Properties of the biodegradable compositions in various embodiments and comparative examples

[0079]

[0080]

[0081] According to the data in Table 4, the initial dart impact of the biodegradable composition in Examples 1 to 15 is ≥200g, and the dart impact after aging for 15 days is ≥80g, and the retention rate reaches more than 40%, indicating that the biodegradable film produced by the biodegradable composition of the present invention under the low blow-up ratio process has excellent dart drop performance and ultra-long shelf life. At the same time, according to Comparative Example 1, Example 2, Example 1, Example 3 and Comparative Example 2, it can be seen that with the increase of the molar proportion of terephthalic acid monomer units in the PBAT resin, the initial dart drop impact of the biodegradable composition and the dart drop impact after aging for 15 days of double 60 show a trend of increasing first and then decreasing; according to Comparative Example 3, it can be found that the combination of PLA resin as an amorphous resin with PBAT resin, inorganic filler and lubricant can give the biodegradable composition good initial dart drop performance, but it will decay rapidly, that is, it cannot achieve a long shelf life. In addition, according to Comparative Examples 4 and 5, it can be seen that when the particle size of the inorganic filler is too large, the initial dart drop performance of the biodegradable composition will be poor.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A biodegradable composition, characterized in that By weight, it includes the following components: PBAT resin 44-90 parts, amorphous resin 5-15 parts, inorganic filler 5-40 parts; Based on the total molar amount of the terephthalic acid monomer unit and the adipic acid monomer unit in the PBAT resin, the molar proportion of the terephthalic acid monomer unit is 47% to 49%; The amorphous resin is at least one of PPC-P, PMMA, PETG, and PCTG; The inorganic filler includes at least one of calcium carbonate and talc; The particle size D of the calcium carbonate 50 <5μm; and / or, the particle size D of the talc 50 <8μm.

2. The biodegradable composition according to claim 1, characterized in that The biodegradable composition comprises the following components in parts by weight: 52.5 to 66.5 parts of PBAT resin, 8 to 12 parts of amorphous resin, and 25 to 35 parts of inorganic filler.

3. The biodegradable composition according to claim 1, characterized in that The particle size D of the calcium carbonate 50 1~3μm.

4. The biodegradable composition according to claim 1, characterized in that The particle size D of the talcum powder 50 0.5~6μm.

5. The biodegradable composition according to claim 1, characterized in that The melt mass flow rate of the PBAT resin at 190° C. and 2.16 kg is 2 to 10 g / 10 min.

6. The biodegradable composition according to claim 1, characterized in that The components of the biodegradable composition also include 0 to 1 parts by weight of a lubricant.

7. The biodegradable composition according to claim 6, characterized in that The lubricant comprises at least one of erucamide, oleamide, monoglycoside ester, N,N'-ethylene bisstearamide, Fischer wax, pentaerythritol stearate, fatty acid amide and stearic acid.

8. The method for preparing the biodegradable composition according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing the components uniformly and then melting and extruding the components to obtain a biodegradable composition.

9. Use of the biodegradable composition according to any one of claims 1 to 7 in the preparation of a biodegradable film.

10. A food packaging bag, shopping bag or agricultural mulch film, characterized in that: Made from the biodegradable composition according to any one of claims 1 to 7.

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