A biodegradable composition, its preparation method and application

Abstract

The present invention belongs to the technical field of polymer materials, and particularly relates to a biodegradable composition, a preparation method thereof and an application. A biodegradable composition comprises the following components in parts by weight: 40-91 parts of a biodegradable polyester, 2-20 parts of polylactic acid, 7-40 parts of an inorganic filler, and 0.1-0.8 part of a chain extender; the complex viscosity of the biodegradable polyester at a high frequency of 100 Hz is 50-500 Pa·S; the melt flow rate of the biodegradable polyester under the test conditions of 190 °C and 2.16 kg is 2-10 g / 10 min. The biodegradable composition of the present invention can effectively control the generation of perforation air leakage, and the heat seal strength of the formed film bag is ≥ 6 N / 15 mm, and fluorine-containing organic compounds can be not used.

Description

Technical Field

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

[0002] Compared with traditional PE, in the production process of blown film of the biodegradable material flexible biodegradable polyester + PLA-MD material, the phenomenon of perforation and air leakage often occurs, seriously affecting the stability of production. When perforation and air leakage occur, it is only possible to stop the machine to clean the machine again and then produce the film bubble. Such continuous shutdown and cleaning greatly affect the production efficiency and cause waste of material and labor costs. In the traditional PE blown film industry, the current method to solve perforation and air leakage is to increase the die gap. However, this will make it difficult to control the thickness of the film. In addition, there is also a method to solve it by adding fluorine-containing processing aids. Fluorine-containing processing aids first cause great pollution to the environment and are also carcinogenic. In addition, it is not allowed in the field of biodegradable materials.

[0003] Patent CN 115716958 A describes that through the synergistic effect of the internal lubricant polyethylene wax and zinc stearate with PPA, the cleaning cycle of the die can be extended and perforation and air leakage can be alleviated. However, zinc stearate in this patent is generally considered to have a destructive effect on biodegradable polyesters, easily causing the aging performance of biodegradable materials, resulting in a rapid decline in mechanical properties and affecting its application. In addition, both polyethylene wax and PPA used in the patent belong to non-biodegradable substances, and too high content is likely to cause the product to not meet industrial composting degradation. Summary of the Invention

[0004] The present invention aims to provide a biodegradable composition, a preparation method thereof, and an application thereof. The biodegradable composition of the present invention can effectively control the generation of perforation and air leakage, and the heat seal strength of the formed film bag is ≥6N / 15mm, and fluorine-containing organic compounds can be not used.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A biodegradable composition, comprising the following components in parts by weight: 40-91 parts of biodegradable polyester, 2-20 parts of polylactic acid, 7-40 parts of inorganic filler, 0.1-0.8 part of chain extender;

[0006] The high-frequency 100Hz complex viscosity of the biodegradable polyester is 50-500 Pa·S;

[0007] The melt flow rate of the biodegradable polyester at 190°C under a load of 2.16 kg is 2-10 g / 10 min. The test method of the melt flow rate refers to the ISO-1133 standard.

[0008] Testing method for high-frequency 100Hz complex viscosity number of the present invention: Use a rotational rheometer (Discovery HR-2, TA instruments). Load the sample into the rheometer and equilibrate at 150 °C for 5 minutes. Then perform a strain sweep experiment with a strain of 1.0% and conduct a strain sweep test at a shear rate from 0.01 Hz to 100 Hz, and read the complex viscosity at 100 Hz.

[0009] Preferably, the biodegradable composition comprises the following components in parts by weight: 55-90 parts of biodegradable polyester, 3-12 parts of polylactic acid, 7-33 parts of inorganic filler, and 0.2-0.6 parts of chain extender.

[0010] Preferably, the high-frequency 100Hz complex viscosity number of the biodegradable polyester is 100-400 Pa·S.

[0011] Preferably, the melt flow rate of the biodegradable polyester at 190 °C under a load of 2.16 kg is 3.5-8 g / 10 min.

[0012] The biodegradable polyester of the present invention is selected from aliphatic copolyesters and / or aliphatic-aromatic copolyesters.

[0013] Preferably, the biodegradable polyester is selected from one or a combination of several of aliphatic-aromatic copolyesters.

[0014] Preferably, the T content of the aliphatic-aromatic copolyester is 40-60%.

[0015] The T content of the biodegradable polyester of the present invention is the molar ratio of terephthalic acid units (PTA) to the total dibasic acid units of the biodegradable polyester.

[0016] More preferably, the aliphatic-aromatic copolyester can be selected from one or a combination of two of poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene sebacate-co-terephthalate) (PBSeT).

[0017] The preparation method of the aliphatic-aromatic copolyester of the present invention comprises the following steps: Add terephthalic acid, adipic acid, and an excessive amount of 1,4-butanediol and glycerol, stir at 150-200 °C for 1-5 hours, then add tetrabutyl titanate, raise the temperature to 220-250 °C, turn on the vacuum, and react for 2-5 hours to obtain the aliphatic-aromatic copolyester.

[0018] The source of the aliphatic-aromatic copolyester of the present invention is not limited to the above preparation method and can also be from commercially available products.

[0019] More preferably, the aliphatic copolyester is selected from at least one of conventional aliphatic polyesters in the art such as poly(butylene succinate-adipate) resin (PBSA).

[0020] In the biodegradable composition of the present invention, the content of the biodegradable polyester is not less than 35 wt%.

[0021] Preferably, the polylactic acid is selected from at least one of PLLA, PDLA, and PLLA / PDLA copolymers.

[0022] Preferably, the melt flow rate of the polylactic acid at 190 °C under a load of 2.16 kg is 1 - 20 g / 10 min. The test method for the melt flow rate refers to the ISO-1133 standard.

[0023] More preferably, the melt flow rate of the polylactic acid at 190 °C under a load of 2.16 kg is 4 - 15 g / 10 min.

[0024] Preferably, the glass transition temperature of the polylactic acid is 40 - 60 °C.

[0025] Preferably, the inorganic filler is at least one of calcium carbonate and talcum powder.

[0026] Preferably, the inorganic filler is calcium carbonate modified or unmodified with a surfactant.

[0027] The method for preparing the calcium carbonate modified with a surfactant in the present invention is as follows: Put the raw calcium carbonate into a high-speed mixer, add a surface activator, set the rotation speed of the high-speed mixer to 40 Hz, and the mixing time is 5 - 10 min, then mix to obtain the calcium carbonate modified with a surfactant.

[0028] Preferably, the chain extender includes at least one of epoxy reactive chain extenders and isocyanate chain extenders.

[0029] The epoxy reactive chain extender can be selected from acrylate and styrene copolymer ADR4370 (BASF) containing epoxy functional groups, etc.; the isocyanate chain extender can be selected from diphenylmethane diisocyanate MDI, toluene diisocyanate TDI, etc.

[0030] Preferably, the D50 particle size of the inorganic filler is ≤ 6 μm. The test method for the D50 particle size is determined according to the method of GB / T 19077.1 "Laser diffraction method for particle size analysis".

[0031] Preferably, the D50 particle size of the inorganic filler is ≤ 5 μm.

[0032] Preferably, the biodegradable composition further includes 0.1 - 2 parts of an auxiliary agent.

[0033] Preferably, the auxiliary agent includes at least one of an antiblocking agent and a lubricant.

[0034] Preferably, the antiblocking agent includes at least one of talcum powder, silica, and PE wax.

[0035] Preferably, the lubricant includes at least one of erucamide, oleamide, glycerol monostearate, pentaerythritol stearate, PE wax, and ethylene bisstearamide (EBS).

[0036] Preferably, the number of perforation air leaks of the biodegradable composition is ≤3 times, and the heat seal strength is ≥6 N / 15 mm.

[0037] The present invention also claims protection for a method for preparing the biodegradable composition, comprising the following steps:

[0038] Premix the auxiliary agent, chain extender, polylactic acid, and part of the biodegradable polyester to obtain a premix. Feed the premix and the remaining biodegradable polyester into the main feed, and feed the inorganic filler into the side feed. Then, perform melt extrusion granulation, cooling, air drying, pelletizing, drying, and homogenization to obtain the biodegradable composition.

[0039] Preferably, the part of the biodegradable polyester is 10-75% of the total mass of the biodegradable polyester.

[0040] Preferably, the rotation speed of the premixing is 240-400 rpm.

[0041] Preferably, the temperature of the melt extrusion granulation is 150-200 °C.

[0042] The present invention also claims protection for a food packaging film / bag prepared from the biodegradable composition.

[0043] The present invention also claims protection for the application of the biodegradable composition in the field of food bags.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The biodegradable composition of the present invention can effectively control the occurrence of perforation air leakage. The number of perforation air leaks is ≤3 times, and the heat seal strength of the formed film bag is ≥6 MPa. At the same time, fluorine-containing organic compounds can be not used, which is safer and more environmentally friendly.

[0046] (2) The components used in the present invention are common substances in the field of biodegradable material modification. By the synergistic effect of different components, the perforation air leakage phenomenon is optimized, which is a more feasible solution applicable to the biodegradable field and will not affect the aging performance and industrial composting performance. Detailed Embodiments

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] In the following examples and comparative examples, unless otherwise specified, the experimental methods used are conventional methods. Unless otherwise specified, the antiblocking agent is obtained commercially, and the same antiblocking agent is used in parallel experiments.

[0049] The descriptions of the raw materials used in the examples and comparative examples are shown in Table 1.

[0050] Table 1

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057] Examples 1 to 17 and Comparative Examples 1 to 6

[0058] The biodegradable compositions of Examples 1 to 17 and Comparative Examples 1 to 6, the components and parts by weight are shown in Tables 2 to 4.

[0059] The preparation method of the biodegradable compositions of Examples 1 to 17 and Comparative Examples 1 to 6 includes the following steps:

[0060] Premix the auxiliary agent, chain extender, polylactic acid and part of the biodegradable polyester to obtain a premix. Feed the premix and the remaining biodegradable polyester into the main feed, and the inorganic filler into the side feed, and perform melt extrusion granulation, cooling, air drying, pelletizing, drying and homogenization to obtain the biodegradable composition. Wherein, part of the biodegradable polyester is 50% of the total mass of the biodegradable polyester; the rotation speed of the premixing is 300 rpm; the temperature of the melt extrusion granulation is 150 - 200 °C.

[0061] Table 2 Component dosage in the examples (parts by weight)

[0062]

[0063]

[0064] Table 3 Component Dosages in Examples (parts by weight)

[0065]

[0066] Table 4 Component Dosages in Comparative Examples (parts by weight)

[0067]

[0068] Performance Testing

[0069] The biodegradable compositions prepared in the examples and comparative examples were subjected to perforation air leakage and heat seal strength tests.

[0070] Perforation air leakage test method: Use a single-screw blown film machine with a diameter of 45, a die with a die gap of 1.8 mm, a die diameter of 70 mm, a blow-up ratio of 3.0, a set temperature of 150 °C, a blown film frequency of 30 Hz, control the film thickness at 20 μm, continuously blow the film for 10 h, observe the number of times of perforation air leakage, the pause time when perforation air leakage occurs, and continue timing after the film is re-stretched and stabilized. The minimum requirement is ≤ 3 times / 10 h.

[0071] The heat seal strength test was carried out in accordance with the standard of GB / T 2358-1998. The requirement is ≥ 6 MPa.

[0072] The test results are shown in Table 5.

[0073] Table 5 Performance Test Results

[0074]

[0075]

[0076] From the data in Table 4, it can be known that the biodegradable composition prepared in the examples of the present invention can effectively control the occurrence of perforation air leakage, the number of perforation air leakage can be controlled within 3 times / 10 h, and the heat seal strength of the formed film bag is ≥ 6 MPa, and can be in the range of 6.1 - 10.6 MPa.

[0077] The intrinsic viscosity of the biodegradable polyester selected in Comparative Examples 1-2 was inappropriate, the melt flow rate of the biodegradable polyester selected in Comparative Example 3 was inappropriate, and the intrinsic viscosity and melt flow rate of the biodegradable polyester selected in Comparative Example 4 were inappropriate, resulting in significantly poorer air leakage resistance of the finally prepared biodegradable composition, and the heat seal strength of the film bag was also worse than that of the Examples. Comparative Example 5 did not contain polylactic acid, resulting in a lower heat seal strength of the finally prepared biodegradable composition and significantly poorer air leakage resistance. Comparative Example 6 did not contain a chain extender, resulting in significantly poorer air leakage resistance of the finally prepared biodegradable composition, a poorer heat seal strength of the film bag, and the separation of different components at the die orifice and precipitation at the die orifice due to poor compatibility.

[0078] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A biodegradable composition, characterized in that, It comprises the following components by weight: 40-91 parts of biodegradable polyester, 2-20 parts of polylactic acid, 7-40 parts of inorganic filler, and 0.1-0.8 part of chain extender; the biodegradable polyester is selected from polybutylene terephthalate adipate, polybutylene terephthalate sebacate or polybutylene succinate-adipate resin; The high-frequency complex viscosity number of the biodegradable polyester at 100 Hz is 50-500 Pa·S; The melt flow rate of the biodegradable polyester at 190 °C under a load of 2.16 kg is 2-10 g / 10 min.

2. The biodegradable composition according to claim 1, wherein It comprises the following components by weight: 55-90 parts of biodegradable polyester, 3-12 parts of polylactic acid, 7-33 parts of inorganic filler, and 0.2-0.6 part of chain extender.

3. The biodegradable composition according to claim 1, wherein, It comprises at least one of the following (1)-(4): (1) The melt flow rate of the biodegradable polyester at 190 °C under a load of 2.16 kg is 3.5-8 g / 10 min; (2) The polylactic acid is selected from at least one of PLLA, PDLA, and PLLA / PDLA copolymers; (3) The melt flow rate of the polylactic acid at 190 °C under a load of 2.16 kg is 1-20 g / 10 min; (4) The glass transition temperature of the polylactic acid is 40-60 °C.

4. The biodegradable composition according to claim 1, wherein It comprises at least one of the following (1)-(2): (1) The inorganic filler is at least one of calcium carbonate and talcum powder; (2) The chain extender comprises at least one of epoxy reaction type chain extender and isocyanate chain extender.

5. The biodegradable composition according to claim 4, characterized in that, The D50 particle size of the inorganic filler ≤ 6 µm.

6. The biodegradable composition according to claim 1, wherein The biodegradable composition further comprises 0.1-2 parts of auxiliary agent.

7. A method for preparing a biodegradable composition according to any one of claims 1 to 6, characterized in that, It comprises the following steps: Premix the auxiliary agent, chain extender, polylactic acid and part of the biodegradable polyester to obtain a premix, main-feed the premix and the remaining biodegradable polyester, side-feed the inorganic filler, melt-extrude and pelletize, cool, air-dry, cut the pellets, dry and homogenize to obtain the biodegradable composition.

8. The preparation method according to claim 7, characterized in that, It comprises at least one of the following (1)-(3): (1) The part of the biodegradable polyester is 10-75% of the total mass of the biodegradable polyester; (2) The rotation speed of the premixing 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, It is prepared from the biodegradable composition as described in any one of claims 1-6.

10. Use of a biodegradable composition as described in any one of claims 1-6 in the field of food bags.

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