Biodegradable composition, and preparation method and use therefor

Abstract

The application relates to a biodegradable composition, and a preparation method and use therefor. The biodegradable composition comprises the following components in parts by weight: 40-91 parts of a biodegradable polyester, 5-20 parts of polylactic acid, 1-10 parts of polybutylene succinate, 7-40 parts of calcium carbonate, and 0.1-3 parts of a nucleating agent. The polylactic acid is a PLLA / PDLA copolymer, and the content of D is 85-99%. The extreme film blowing linear speed of the biodegradable composition at the temperature change rate of 10 C° / min is 80-120 m / min. The biodegradable composition of the present application has excellent film bubble stability, can achieve relatively high extreme linear speed, and facilitates industrial continuous production.

Description

A biodegradable composition and its preparation method and application Technical Field

[0001] The present application belongs to the technical field of polymer materials, and specifically relates to a biodegradable composition, a preparation method and an application thereof. Background Art

[0002] Compared to traditional PE (polyethylene), biodegradable flexible biodegradable polyester + PLA (PLA) - mineral powder MD material often experiences unstable bubbles and film breakage during high-speed film blowing during film production, seriously affecting production efficiency. The only solution to this problem is to stop the machine to clean the machine and then pull the bubble, and reduce the film blowing speed. Alternatively, the film blowing machine can be raised to 6 or even 7 meters and the workshop can be cooled with strong cooling to reduce the temperature and improve bubble stability. This constant shutdown for cleaning significantly affects production efficiency, and upgrading the machine to a higher height or using strong cooling in the workshop will lead to space constraints and waste of costs. The traditional PE industry can enhance bubble stability by adding some PE components with stronger crystallization properties, but PE is not allowed in the biodegradable industry.

[0003] Patent CN102892970B describes an oxygen-regulated polyethylene composition obtained through an oxygen regulation method, whereby its initial relaxation spectrum index (RSI) increases from 10% to 300%, thereby improving the bubble stability of the resulting polyethylene film. However, the patent does not address biodegradable materials. Therefore, there is an urgent need to develop a biodegradable composition that can effectively improve bubble stability and increase the ultimate line speed. Summary of the Invention

[0004] The present application provides a biodegradable composition, a preparation method thereof, and an application thereof. The biodegradable composition of the present application has excellent bubble stability and can achieve a relatively high ultimate line speed, which is beneficial to industrial continuous production.

[0005] The present application provides a biodegradable composition comprising the following components in parts by weight: 40-91 parts of biodegradable polyester, 5-20 parts of polylactic acid, 1-10 parts of polybutylene succinate, 7-40 parts of calcium carbonate, and 0.1-3 parts of a nucleating agent;

[0006] The polylactic acid is a PLLA / PDLA (levorotatory polylactic acid / dextrorotatory polylactic acid) copolymer, wherein the D content is 85-99%.

[0007] In some embodiments, the composition includes the following components in parts by weight: 50-85 parts of biodegradable polyester, 8-15 parts of polylactic acid, 2-8 parts of polybutylene succinate, 8-32 parts of calcium carbonate, and 0.5-2 parts of a nucleating agent.

[0008] In some embodiments, the intrinsic viscosity of the polylactic acid is 1.0-1.85 dL / g.

[0009] In some embodiments, the polybutylene succinate has a composite viscosity of 3000-20000 Pa·S at 0.1 rad / s.

[0010] In some embodiments, the invention comprises at least one feature selected from the group consisting of (1) to (4):

[0011] (1) The biodegradable polyester is an aliphatic-aromatic copolyester;

[0012] (2) the D content of the polylactic acid is 90-98%;

[0013] (3) The D50 particle size of the calcium carbonate is 1-8 μm;

[0014] (4) The nucleating agent includes at least one of talc, montmorillonite, zeolite, EBS (ethylene bisstearamide), hydrazide, and wollastonite.

[0015] In some embodiments, the invention comprises at least one feature selected from the group consisting of (1) to (3):

[0016] (1) The biodegradable polyester is selected from at least one of polybutylene adipate terephthalate and polybutylene sebacate terephthalate, and the T content of the biodegradable polyester is 44-52%;

[0017] (2) The D50 particle size of the calcium carbonate is 2-5 μm;

[0018] (3) The nucleating agent is a composition of talc and hydrazide.

[0019] The present application provides a method for preparing the biodegradable composition, which is characterized by comprising the following steps:

[0020] The nucleating agent, polybutylene succinate, polylactic acid and part of the biodegradable polyester are premixed to obtain a premix, the premix and the remaining biodegradable polyester are mainly fed and calcium carbonate is side-fed, melt-extruded and granulated, cooled, air-dried, granulated, dried and homogenized to obtain the biodegradable composition.

[0021] In some embodiments, the preparation method includes at least one feature selected from the following (1) to (3):

[0022] (1) The partially biodegradable polyester accounts for 10 to 75% of the total mass of the biodegradable polyester;

[0023] (2) The rotation speed of the premix is ​​240-400 rpm;

[0024] (3) The temperature of the melt extrusion granulation is 150-200°C.

[0025] The present application also claims protection for a food packaging film / bag prepared from raw materials comprising the biodegradable composition.

[0026] The present application also claims protection for a use of the biodegradable composition in the field of catering bags.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] This application controls the D content of PLA, uses PBS, and performs triple synergistic crystallization of a nucleating agent, so that the film bubbles can be quickly crystallized and shaped, thereby maintaining the stability of the film bubbles and increasing the maximum linear speed to a higher level. DETAILED DESCRIPTION

[0029] The present application adopts the following technical solution: a biodegradable composition comprising the following components in parts by weight: 40-91 parts of biodegradable polyester, 5-20 parts of polylactic acid, 1-10 parts of polybutylene succinate, 7-40 parts of calcium carbonate, and 0.1-3 parts of a nucleating agent; the polylactic acid is a PLLA / PDLA copolymer, wherein the D content is 85-99%;

[0030] In some embodiments, the biodegradable composition has a limiting film blowing line speed of 80-120 m / min at a temperature change rate of 10° C. / min.

[0031] In some embodiments, the biodegradable composition comprises the following components in parts by weight: 50-85 parts of biodegradable polyester, 8-15 parts of polylactic acid, 2-8 parts of polybutylene succinate, 8-32 parts of calcium carbonate, and 0.5-2 parts of a nucleating agent.

[0032] In some embodiments, the intrinsic viscosity of the polylactic acid is 1.0-1.85 dL / g.

[0033] In some embodiments, the intrinsic viscosity of the polylactic acid is 1.1-1.7 dL / g.

[0034] In some embodiments, the test method of the intrinsic viscosity of the present application is: at 25°C, accurately weigh 0.1250±0.0005g of sample and dissolve it in 25ml (o-dichlorobenzene: phenol = 2:3 mass ratio) solution, heat and stir at 110°C until the resin is completely dissolved, and measure with a viscometer.

[0035] In some embodiments, when the polylactic acid is a PLLA / PDLA copolymer, the PLLA / PDLA copolymer can be a conventional commercial product or can be prepared using conventional methods in the art.

[0036] In some embodiments, the PLLA / PDLA copolymer is prepared as follows: D-lactide, meso-lactide dissolved in hexylene glycol, and a catalyst (such as stannous octoate) are mixed and subjected to a ring-opening polymerization reaction at a reaction temperature of 130-150° C. and a reaction pressure of 1100-1500 Pa for 1-5 hours, followed by a reaction temperature of 160-180° C. and a reaction pressure of 250-350 Pa for 2-10 hours to obtain a polymer solid. The polymer solid is dissolved in 5wt% chloroform by refluxing, the solution is filtered, and precipitated with ethanol in a volume ratio of 5:1 to obtain a white flocculent precipitate, which is the PLLA / PDLA copolymer.

[0037] In some embodiments, the polybutylene succinate has a composite viscosity at 0.1 rad / s of 3,000 to 20,000 Pa·s. In some embodiments, the polybutylene succinate has a composite viscosity at 0.1 rad / s of 5,000 to 20,000 Pa·s. A higher composite viscosity under low shear (also known as composite viscosity) indicates greater entanglement of the molecular chains, which facilitates rapid crystallization of the PBS (polybutylene succinate).

[0038] In some embodiments, the 0.1 rad / s complex viscosity is measured using a rotational rheometer. In some embodiments, a sample is loaded into the rheometer and equilibrated at 150°C for 5 minutes. A strain sweep experiment is then performed with a strain of 1.0% and a shear rate ranging from 0.1 rad / s to 628 rad / s. The complex viscosity at 0.1 rad / s is then measured.

[0039] In some embodiments, the polybutylene succinate can be a conventional commercial product or can be prepared by conventional methods in the art.

[0040] In some embodiments, the preparation method of polybutylene succinate is as follows: BDO (1,4-butanediol) and succinic acid are mixed and reacted. After the reactor atmosphere is replaced with nitrogen twice, the temperature is raised to 180-200°C and esterification is carried out for 2-3 hours. After the esterification reaction is completed, a catalyst (such as tetrabutyl titanate (TBT)) and glycerol (glycerol can be added at the discretion of a skilled artisan based on actual conditions) are added to the reactor. The vacuum system is activated to a vacuum level of 250-350 Pa, and the temperature is raised to 230-250°C for reaction. The reaction is continued for 3-6 hours, and the reaction is stopped when a significant increase in stirring power is observed. Finally, the copolymer is removed from the reactor for drawing, cooling, and pelletizing.

[0041] In some embodiments, the biodegradable polyester is an aliphatic-aromatic copolyester.

[0042] In some embodiments, the biodegradable polyester is selected from at least one of polybutylene adipate terephthalate (PBAT) and polybutylene sebacate terephthalate (PBSeT), and the T content of the biodegradable polyester is 44-52%.

[0043] In some embodiments, the biodegradable polyester has a T content of 46-50%.

[0044] The T content of the biodegradable polyester described herein is the molar ratio of terephthalic acid units (PTA) to the total dibasic acid units of the biodegradable polyester.

[0045] In some embodiments, when the biodegradable polyester of the present application is polybutylene adipate terephthalate (PBAT), the PBAT can be a conventional commercial product or can be prepared by conventional methods in the art.

[0046] In some embodiments, the preparation method of the PBAT is as follows: add terephthalic acid, adipic acid and excess 1,4-butanediol and glycerol, stir at 150-200° C. for 1-5 hours, then add a catalyst (such as tetrabutyl titanate), heat to 220-250° C., and react at a pressure of 280-320 Pa for 2-5 hours to obtain the PBAT.

[0047] In some embodiments, the intrinsic viscosity of the PBAT is 1.3-2.0 dL / g.

[0048] In some embodiments, the intrinsic viscosity of the PBAT of the present application is measured in accordance with GB / T 17931-1999 in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 in a constant temperature water bath at 25±0.05° C., with a sample concentration of 5 mg / ml.

[0049] In some embodiments, the D content of the polylactic acid is 90-98%. In some embodiments, the molar content of D-lactic acid (i.e., D content) in the polylactic acid described herein is measured according to the following test method: a polylactic acid sample is degraded by transesterification with methanol at 150° C. in a pressure vessel and analyzed by gas chromatography, wherein the D-lactic acid content in the polylactic acid is calculated by the peak area ratio of L- and D-methyl lactate:

[0050] For each GC run, the D-lactic acid content of the sample solution was calculated as follows:

[0051] ADML: D-methyl lactate peak area;

[0052] ALML: L-methyl lactate peak area;

[0053] The average D-lactic acid content of the sample solution was calculated from the obtained single-value D-lactic acid content.

[0054] The content of D-lactic acid in the PLA samples was taken as the average value of the D-lactic acid content found in all sample solutions prepared from the PLA samples.

[0055] In some embodiments, the D50 particle size of the calcium carbonate is 1-8 μm. In some embodiments, the D50 particle size of the calcium carbonate is 2-5 μm. In some embodiments, the D50 particle size is measured according to GB / T 19077.1 "Particle Size Analysis by Laser Diffraction Method".

[0056] In some embodiments, the nucleating agent includes at least one of talc, montmorillonite, zeolite, EBS, hydrazide, and wollastonite.

[0057] In some embodiments, in the biodegradable composition described herein, the content of the biodegradable polyester is not less than 50%.

[0058] The present application also claims a method for preparing the biodegradable composition, comprising the following steps:

[0059] The nucleating agent, polybutylene succinate, polylactic acid and part of the biodegradable polyester are premixed to obtain a premix, the premix and the remaining biodegradable polyester are mainly fed and calcium carbonate is side-fed, melt-extruded and granulated, cooled, air-dried, granulated, dried and homogenized to obtain the biodegradable composition.

[0060] In some embodiments, the partially biodegradable polyester accounts for 10 to 75% of the total mass of the biodegradable polyester.

[0061] In some embodiments, the premixing speed is 240-400 rpm.

[0062] In some embodiments, the temperature of the melt extrusion granulation is 150-200°C.

[0063] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0064] In the following examples and comparative examples, the experimental methods used are conventional methods unless otherwise specified.

[0065] The raw materials used in the examples and comparative examples are shown in Table 1.

[0066] Table 1

[0067] Examples 1 to 20 and Comparative Examples 1 to 5

[0068] The components and weight proportions of the biodegradable compositions of Examples 1 to 20 and Comparative Examples 1 to 5 are shown in Tables 2 to 4.

[0069] The preparation method of the biodegradable composition of Examples 1 to 20 and Comparative Examples 1 to 4 comprises the following steps:

[0070] The biodegradable composition is prepared by premixing a nucleating agent, polybutylene succinate, polylactic acid, and a portion of a biodegradable polyester to obtain a premix. The premix is ​​then fed with the remaining biodegradable polyester as a main feed and calcium carbonate as a side feed, melt-extruded into pellets, cooled, air-dried, pelletized, dried, and homogenized. The portion of the biodegradable polyester accounts for 50% of the total mass of the biodegradable polyester. The premixing speed is 300 rpm, and the melt-extrusion pelletizing temperature is 150-200°C.

[0071] Comparative Example 5

[0072] The preparation method of the biodegradable composition of Comparative Example 5 comprises the following steps:

[0073] The biodegradable composition is prepared by premixing a nucleating agent, polycaprolactone, polylactic acid, and a portion of a biodegradable polyester to obtain a premix. The premix is ​​then fed with the remaining biodegradable polyester as a main feed and calcium carbonate as a side feed, melt-extruded into pellets, cooled, air-dried, pelletized, dried, and homogenized. The portion of the biodegradable polyester accounts for 50% of the total mass of the biodegradable polyester. The premixing speed is 300 rpm, and the melt-extrusion pelletizing temperature is 150-200°C.

[0074] Table 2 Component dosage (parts by weight)

[0075] Table 3 Component dosage (parts by weight)

[0076] Table 4 Comparative Examples Component Amounts (parts by weight)

[0077] Performance Testing

[0078] The biodegradable compositions prepared in the examples and comparative examples were subjected to a limit film blowing line speed test, and the test method is as follows:

[0079] Maximum film blowing linear speed: Use a 45 single-screw film blowing machine, a die with a die gap of 1.8mm, a die diameter of 70mm, a blow-up ratio of 3.0, a set temperature of 150℃, a film blowing frequency of 40Hz, a film thickness controlled at 20μm, and blow the film continuously for 10 minutes without breaking the film. Increase the linear speed by 5m / min each time until the bubble becomes unstable and the film breaks. The linear speed before the film break is the maximum film blowing linear speed.

[0080] The performance test results are shown in Table 5.

[0081] Table 5 Performance test results

[0082] From the experimental data in Table 5, it can be seen that the biodegradable composition prepared in the examples of the present application has a relatively high ultimate film blowing line speed, wherein the ultimate film blowing line speed can be achieved above 88 m / min and maintained in the range of 91-118 m / min.

[0083] In Comparative Example 1, the D content of the polylactic acid selected was inappropriate, and the ultimate film blowing speed of the biodegradable composition obtained could only reach 79 m / min; in Comparative Example 2, no PBS component was added, and in Comparative Example 3, an excessive amount of PBS was added, and the ultimate film blowing speed of the biodegradable composition finally obtained was worse than that of the example; in Comparative Example 4, no nucleating agent was added, and the ultimate film blowing speed of the biodegradable composition obtained was significantly lower than that of the example; in Comparative Example 5, PCL was used to replace PBS, and the ultimate film blowing speed of the biodegradable composition obtained was significantly worse.

[0084] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed in this application shall be covered by the claims of this application.

Claims

1. A biodegradable composition, characterized in that The invention comprises the following components in parts by weight: 40-91 parts of biodegradable polyester, 5-20 parts of polylactic acid, 1-10 parts of polybutylene succinate, 7-40 parts of calcium carbonate, and 0.1-3 parts of a nucleating agent; The polylactic acid is a PLLA / PDLA (levorotatory polylactic acid / dextrorotatory polylactic acid) copolymer, wherein the D content is 85-99%.

2. The biodegradable composition according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 50-85 parts of biodegradable polyester, 8-15 parts of polylactic acid, 2-8 parts of polybutylene succinate, 8-32 parts of calcium carbonate and 0.5-2 parts of a nucleating agent.

3. The biodegradable composition according to claim 1, characterized in that: The intrinsic viscosity of the polylactic acid is 1.0-1.85 dL / g.

4. The biodegradable composition according to claim 1, characterized in that: The composite viscosity of the polybutylene succinate at 0.1 rad / s is 3000-20000 Pa·S.

5. The biodegradable composition according to claim 1, characterized in that: The invention comprises at least one feature selected from the following (1) to (4): (1) The biodegradable polyester is an aliphatic-aromatic copolyester; (2) The D content of the polylactic acid is 90-98%; (3) The D50 particle size of the calcium carbonate is 1-8 μm; (4) The nucleating agent includes at least one of talc, montmorillonite, zeolite, EBS (ethylene bisstearamide), hydrazide, and wollastonite.

6. The biodegradable composition according to claim 5, characterized in that: The invention comprises at least one feature selected from the following (1) to (3): (1) The biodegradable polyester is selected from at least one of polybutylene adipate terephthalate and polybutylene sebacate terephthalate, and the T content of the biodegradable polyester is 44-52%; (2) The D50 particle size of the calcium carbonate is 2-5 μm; (3) The nucleating agent is a composition of talc and hydrazide.

7. A method for preparing a biodegradable composition according to any one of claims 1 to 6, characterized in that: The following steps are involved: The nucleating agent, polybutylene succinate, polylactic acid and part of the biodegradable polyester are premixed to obtain a premix, the premix and the remaining biodegradable polyester are mainly fed, calcium carbonate is side fed, melt extruded into granules, cooled, air-dried, granulated, dried and homogenized to obtain the biodegradable composition.

8. The preparation method according to claim 7, characterized in that: The invention comprises at least one feature selected from the following (1) to (3): (1) The partially biodegradable polyester accounts for 10 to 75% of the total mass of the biodegradable polyester; (2) The rotation speed of the premix is ​​240-400 rpm; (3) The temperature of the melt extrusion granulation is 150-200°C.

9. A food packaging film / bag, characterized in that: The biodegradable composition is prepared from raw materials including the biodegradable composition according to any one of claims 1 to 6.

10. Use of the biodegradable composition according to any one of claims 1 to 6 in the field of catering bags.

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