A polyglycolic acid reinforced polyester material, a tear-resistant degradable ground film and a preparation method thereof

Abstract

The present invention relates to a polyglycolic acid reinforced polyester material and its tear-resistant and degradable mulch film. The polyglycolic acid reinforced polyester material includes: a base material and a reinforcing material, wherein the base material contains polyhydroxyalkanoate and a degradable polyester, and the reinforcing material is polyglycolic acid. By introducing polyglycolic acid as a rigid and degradable material into the mulch film material, the comprehensive mechanical properties and processing properties of the mulch film can be effectively enhanced. While increasing the elongation rate of the mulch film, the elastic modulus and right-angle tear strength are significantly improved, thereby effectively improving the use effect of the mulch film during use and extending the service life of the mulch film.

Description

Technical Field

[0001] The present invention belongs to the field of degradable materials, and particularly relates to a polyglycolic acid reinforced polyester material, a tear-resistant degradable ground film and a preparation method thereof. Background Art

[0002] The plastic mulching technology was formed in the mid-20th century. With the development of high molecular compounds, extremely thin polyethylene films were used to replace traditional covering materials such as straw, horse manure, wormwood, and sandstone to cover the ground, achieving the purpose of water retention, fertilizer retention, and temperature increase. Since then, using agricultural plastic films to cover and cultivate crops has been one of the important measures to promote crop yield increase and agricultural modernization.

[0003] The traditional ground films used are mainly polyethylene and polyvinyl chloride ground films, which are extremely difficult to degrade, with a degradation period reaching up to hundreds of years. Moreover, after the ground films age and break, the residual films are not easily degraded in the soil, difficult to recycle, and accumulating in the soil will cause land pollution, serious damage to the soil structure, loss of fertility, and reduction of crop yields. The long-term use of such ground films causes long-term and difficult-to-solve harm to the land. Therefore, biodegradable ground films, which have the same warming and moisturizing effects and can be completely degraded without polluting the soil, have received extensive attention.

[0004] Currently, in the market of degradable ground films, the commonly used biodegradable polymer materials mainly include polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoates (PHA), copolymers of butylene adipate and butylene terephthalate (PBAT), etc. Among them, as a fully biobased degradable material, PHA now has a relatively mature industrial PHA industrial chain, and it is expected to achieve low-cost production of PHA. Compared with petroleum-based plastics, it has certain competitive potential and is a potential material for degradable ground films. However, the disadvantage of PHA is that it degrades too fast, and its mechanical strength is not high, and the processing performance is poor. In the application of degradable ground films, a major disadvantage of PHA ground films is their poor mechanical properties, especially poor tear resistance, which is prone to cracking during use, resulting in the failure of the ground film and unable to achieve the function of retaining water and moisture for crops.

[0005] Chinese Patent CN109177401A mentions a PLA / PBAT ground film with relatively high tear strength and mechanical properties. By adopting a three-layer composite method and changing the addition amount of PLA, the right-angle tear strength of the ground film is improved. However, in this patent, the proportion of PLA added is relatively large, and when the PLA is about 30%, the tear resistance of the ground film is 120 kN / m. Summary of the Invention

[0006] To solve the above problems and overcome the problem that polyhydroxyalkanoate (PHA) mulch films are prone to tearing and failure during use, the present invention introduces polyglycolic acid (PGA) as a rigid degradable material into the PHA mulch film, effectively enhancing the comprehensive mechanical properties and processing properties of the PHA mulch film. While increasing the elongation rate of the mulch film, the elastic modulus and right-angle tear strength of the mulch film are also greatly improved, effectively improving the use effect of the mulch film during use and extending the service life of the mulch film.

[0007] One object of the present invention is to provide a polyglycolic acid-reinforced polyester material, comprising: a base material and a reinforcing material, wherein the base material comprises polyhydroxyalkanoate and a degradable polyester, and the reinforcing material is polyglycolic acid.

[0008] According to an embodiment of the present invention, in the polyglycolic acid-reinforced polyester material:

[0009] Based on 100 parts by weight of the total weight of the base material, the reinforcing material is 0.1 to 15 parts, preferably 1 to 10 parts; the reinforcing material can be any value among 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts or any value within any two numerical ranges; more preferably, based on 100 parts by weight of the total weight of the base material, the reinforcing material is 1 to 5 parts, which can be any value among 1 part, 2 parts, 3 parts, 4 parts, 5 parts or any value within any two numerical ranges.

[0010] Based on 100 parts by weight of the total weight of the base material, the polyhydroxyalkanoate is 1 to 50 parts, and the degradable polyester is 50 to 99 parts; preferably, based on 100 parts by weight of the total weight of the base material, the polyhydroxyalkanoate is 1 to 30 parts, such as any value among 1 part, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts or any value within any two numerical ranges; the degradable polyester is 70 to 99 parts, such as any value among 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts, 99 parts or any value within any two numerical ranges.

[0011] According to an embodiment of the present invention, the degradable polyester is selected from degradable polyester homopolymers or copolymers, preferably selected from at least one of poly(butylene adipate-co-terephthalate) (PBAT), poly(butylene succinate / butylene terephthalate) (PBST), polylactic acid (PLA), polycaprolactone (PCL), poly(propylene carbonate) (PPC), poly(butylene succinate) (PBS), and the degradable polyester can be composed of one or more of the above components mixed in any ratio.

[0012] According to an embodiment of the present invention, the polyhydroxyalkanoate has a structural unit shown in one of formulas (I) to (III):

[0013]

[0014] In formula (I), R 1 is H or a C1-C16 hydrocarbon group, and n is a positive integer between 1 and 10,000;

[0015]

[0016] In formula (II), R 2 and R 3 are different and are H or a C1-C16 hydrocarbon group; m and n are positive integers between 1 and 10,000;

[0017]

[0018] In formula (III), R 4 and R 5 are different and are H or a C1-C16 hydrocarbon group; m and n are positive integers between 1 and 10,000;

[0019] Preferably, the polyhydroxyalkanoate is selected from at least one of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate);

[0020] The weight-average molecular weight of the polyglycolic acid is 30,000-500,000 g / mol, preferably 50,000-400,000 g / mol;

[0021] The weight-average molecular weight of the biodegradable polyester is 10,000-180,000 g / mol, preferably 50,000-150,000 g / mol;

[0022] The weight-average molecular weight of the polyhydroxyalkanoate is 50,000-800,000 g / mol, preferably 80,000-500,000 g / mol.

[0023] According to an embodiment of the present invention, an additive can be added to the polyglycolic acid-reinforced polyester material, and the additive can adopt a commonly used additive component in the art. Preferably, the additive includes at least one of a nucleating agent, a chain extender, an antiblocking agent, and a stabilizer.

[0024] Specifically, among the above additives:

[0025] The nucleating agent is selected from at least one of nanocrystalline cellulose, talcum powder, silica, and plate-shaped calcium carbonate. In addition to improving the crystallization performance of the material, the nucleating agent also has functions such as increasing the melt compatibility and improving the water resistance performance;

[0026] The chain extender is one or more of a compound or polymer having a reactive group with a carboxyl or hydroxyl group, and a compound containing a plurality of epoxy functional groups. Specifically, the chain extender is selected from at least one of polyfunctional isocyanates, polyfunctional epoxides, and polyfunctional polymers, preferably selected from at least one of hexamethylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, and a terpolymer of styrene-methyl methacrylate-glycidyl methacrylate (ADR);

[0027] The antiblocking agent can be an antiblocking agent commonly used in the art, preferably selected from at least one of oleic acid amide, erucic acid amide, stearic acid amide, and sodium stearate;

[0028] The stabilizer is selected from at least one of ultraviolet absorbers, light stabilizers, antioxidants, and hydrolysis-resistant agents. Among them, the ultraviolet absorber can be a commonly used ultraviolet absorber, preferably selected from at least one of benzotriazole compounds, benzoxazine compounds, benzotriazole compounds, aniline compounds, triazine compounds, and benzophenone compounds, and further can be selected from at least one of UV-P, UV-234, UV-326, UV-327, UV-328, UV-329, and UV-531; the light stabilizer can be a commonly used light stabilizer, preferably selected from at least one of hindered amine light stabilizers and hindered phenol light stabilizers, and further can be selected from at least one of Chimassorb 944, Tinuvin 292, Tinuvin 622, Tinuvin770, and Tinuvin 783; the antioxidant can be a commonly used antioxidant product, preferably selected from at least one of hindered phenol antioxidants and phosphite antioxidants, and further selected from at least one of 168, 264, 300, 425, 626, 627, 1010, and 1076; the hydrolysis-resistant agent is selected from carbodiimide compounds, and further can be selected from hydrolysis-resistant agent Hymax 1010.

[0029] According to an embodiment of the present invention, based on 100 parts by mass of the total weight of the base material, the nucleating agent is 0.02 - 30 parts, the chain extender is 0.01 - 6 parts, the antiblocking agent is 0.02 - 10 parts, and the stabilizer is 0.03 - 30 parts; preferably, the nucleating agent is 1 - 20 parts, the chain extender is 0.05 - 2 parts, the antiblocking agent is 0.05 - 5 parts, and the stabilizer is 0.03 - 20 parts. Among them, the stabilizer can be composed of one or two or more components of ultraviolet absorber, light stabilizer, antioxidant, and hydrolysis-resistant agent added in any proportion as required. Preferably, based on 100 parts by mass of the total weight of the base material, the added ultraviolet absorber, light stabilizer, antioxidant, and hydrolysis-resistant agent are 0.01 - 5 parts by mass, 0.01 - 5 parts by mass, 0.01 - 5 parts by mass, and 0.01 - 5 parts by mass, respectively.

[0030] A second object of the present invention is to provide a method for preparing the above-mentioned polyglycolic acid-reinforced polyester material, which includes mixing components including the polyhydroxyalkanoate, biodegradable polyester, polyglycolic acid, and optionally added additives, and then subjecting them to melt extrusion to obtain the polyglycolic acid-reinforced polyester material. Preferably, the preparation method includes:

[0031] Step 1: Premix the polyhydroxyalkanoate with the optionally added additives to form a premixed powder;

[0032] Step 2: After mixing the biodegradable polyester and polyglycolic acid, add the premixed powder obtained in Step 1, and then perform melt extrusion, cooling, and pelletizing to obtain the polyglycolic acid-reinforced polyester material.

[0033] According to an embodiment of the present invention, the melt extrusion can be carried out using a commonly used melt mixing device in the art. For example, a twin-screw extruder, a mixer, a continuous melt mixer, a single-screw extruder, or a multi-screw extruder can be used. Preferably, a twin-screw extruder is used, and more preferably, a co-rotating or counter-rotating twin-screw extruder is used. According to a specific embodiment of the present invention, the temperature of the melt extrusion is 50 - 350 °C, preferably 50 - 300 °C; the screw speed of the melt extrusion is 5 - 500 rpm, preferably 50 - 300 rpm, and more preferably 100 - 250 rpm. The twin-screw extruders of the present invention include but are not limited to: the Micro 27 twin-screw extruder produced by Leistritz of Germany, which has the function of switching between co-rotating and counter-rotating; the co-rotating twin-screw extruders of models such as PolyLab and EuroLab produced by Thermo Fisher Scientific of the United States; the ZSK 30 co-rotating parallel twin-screw extruder produced by Coperion of Germany, etc.

[0034] A third object of the present invention is to provide a tear-resistant and degradable ground film, which comprises the above-mentioned polyglycolic acid-reinforced polyester material or the polyglycolic acid-reinforced polyester material obtained by the above-mentioned preparation method.

[0035] According to an embodiment of the present invention,

[0036] The thickness of the tear-resistant and degradable ground film is 4-30 μm, preferably 5-25 μm;

[0037] The right-angle tear strength of the tear-resistant and degradable ground film is 50-270 kN / m, preferably 100-250 kN / m;

[0038] The breaking strength of the tear-resistant and degradable ground film is 10-40 MPa, preferably 15-35 MPa;

[0039] The elongation at break of the tear-resistant and degradable ground film is 300-1000%, preferably 500-800%;

[0040] The modulus of the tear-resistant and degradable ground film is 60-200 MPa, preferably 60-150 MPa.

[0041] A fourth object of the present invention is to provide a preparation method of the above-mentioned tear-resistant and degradable ground film, which includes melting and extruding the polyglycolic acid-reinforced polyester material, blowing the film, and cooling to obtain the tear-resistant and degradable ground film. Preferably, the melting and extrusion is carried out by a single-screw extruder. Specifically, the temperature of the melting and extrusion is 150-300 °C, preferably 160-250 °C; the screw speed of the single-screw extruder is 5-200 rpm, preferably 10-150 rpm.

[0042] The present invention uses polyglycolic acid as a rigid complementary biodegradable material. On the one hand, it can enhance the polyhydroxyalkanoate ground film, greatly improving its breaking strength and modulus. At the same time, it can improve the toughness of the film to a certain extent, and its elongation at break also increases. On the other hand, it can effectively improve the tear resistance of the film, and its tear strength is more than 1.5 times higher than that of the ground film without adding polyglycolic acid. By adding polyglycolic acid (PGA) to the polyhydroxyalkanoate ground film, the present invention utilizes the characteristics of high strength and high modulus of PGA to effectively improve the processing stability during the industrial preparation of the ground film material and the stability during the laying process of the ground film, thereby effectively solving the disadvantage that the PHA ground film is prone to tearing and puncturing during use, resulting in the failure of the water retention and heat preservation functions of the ground film, and greatly extending the service life of the PHA ground film.

[0043] In the present invention, an appropriate amount of PGA is added to the PHA film. PGA and PHA are similar in chemical composition and are both aliphatic polyesters. However, the repeating unit carbon chain of PHA is longer, the side chain structure is diverse, it is difficult to crystallize, has low strength, and poor processing performance; the repeating unit carbon chain of PGA is short, the structure is single, it has high strength and is easy to crystallize. When a small amount of PGA (≤5%) is added to the PBAT / PHA film, it can make the crystallization and molding faster during the film blowing process and improve the film blowing stability; at the same time, due to the small addition amount of PGA, PGA is evenly distributed as a discontinuous phase in the film, while improving the strength modulus of the film, its elongation at break is also improved.

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

[0045] 1. The present invention uses polyglycolic acid as a rigid complementary biodegradable material, which can effectively improve the tear resistance of the PHA film and improve the processing stability during the industrial preparation process of the film material and the stability during the film laying process of the film;

[0046] 2. In the present invention, a small amount of polyglycolic acid is introduced into the PHA material, which can effectively improve the strength of the film and further improve the toughness of the film;

[0047] 3. In the present invention, a small amount of polyglycolic acid is introduced into the PHA material, which can improve the disadvantages of slow crystallization and difficult opening during the film blowing process of the PHA film and improve the stability during the film blowing process;

[0048] 4. The preparation method provided by the present invention has a simple process, green and environmentally friendly raw materials, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG. 1 is the first melting curve ( Figure 1A ) and the second melting curve ( Figure 1B ) of the modified particles with different PGA addition amounts in Comparative Example 1 and Examples 1-5. The abscissa is temperature and the ordinate is heat flow. Among them, 0 represents Comparative Example 1, and 1% - 5% represent Examples 1-5 respectively.

[0050] Figure 2 is the breaking strength of the films prepared from the modified particles of Examples 1-6 and Comparative Examples 1, 2, 4.

[0051] Figure 3 is the elongation at break of the films prepared from the modified particles of Examples 1-6 and Comparative Examples 1, 2, 4.

[0052] Figure 4 is the modulus of the films prepared from the modified particles of Examples 1-6 and Comparative Examples 1, 2, 4.

[0053] Figure 5The right-angle tear strength of the plastic film prepared by using the modified particles of Examples 2 to 5 and Comparative Examples 1 and 3. Detailed implementation mode

[0054] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0055] The test instruments and test conditions used in the examples are as follows:

[0056] Determination method of melt index (MFR): According to ISO 1133 standard, using Lloyd Davenport MFI-10 / 230 melt index instrument, barrel temperature 150 °C, weight load 2.16 kg, die diameter 2.095 mm, length 8 mm, preheating time 4 min, automatically cut samples at regular intervals, take the average value of 5 times, and express the test result in grams per 10 minutes (g / 10 min).

[0057] Thermal performance analysis (DSC): The test is carried out on a Discovery series differential scanning calorimeter (DSC) produced by TA Instruments. The processing software is TA Instruments Trios 3.1.5 version. The DSC instrument is equipped with a Refrigerated Cooling System 90 mechanical refrigeration accessory. The test atmosphere is nitrogen with a flow rate of 50 mL / min, and the required sample amount for the test is 5 - 10 mg. The test procedure is as follows: First, stabilize the temperature at 40 °C, then heat up to 220 °C at a rate of 10 °C / min and keep it constant for 1 min, then cool down to -50 °C at a rate of 10 °C / min and keep it constant for 1 min, and then heat up to 220 °C at a rate of 10 °C / min. Record the cooling process and the second heating process to study the thermal performance of the sample. Through DSC testing, the crystallization temperature (T c ), melting temperature (T m ), glass transition (T g ), enthalpy change (H) and other information can be directly obtained by the software.

[0058] Film tensile and right-angle tear tests: According to the ISO 527-3 standard, a 3344-type material testing machine from Instron was used for the tests, and the processing software was Bluehill version 2.31. The film was cut into Type 5 according to the ISO 527-3 standard parallel to the stretching direction (MD) and perpendicular to the stretching direction (CD), and placed in a Bluepard BPS–100CB constant temperature and humidity chamber (temperature 23°C, relative humidity 50%) of Shanghai Yiheng Scientific Instrument Co., Ltd. for 24 hours. During the test, the initial fixture spacing was 75 mm, the test stretching rate was 100 mm / min, and each sample was tested at least 5 times, and the average value was taken.

[0059] In the right-angle tear test, sample preparation and testing were carried out according to the QB / T 1130-91 standard. During the test, the initial fixture spacing was 75 mm, the test stretching rate was 200 mm / min, and each sample was tested at least 5 times, and the average value was taken.

[0060]

Examples 1-5

[0061] In the co-rotating twin-screw extruder (screw diameter 25 mm, L / D = 56) of Krauss Maffei Germany 1 the polyglycolic acid (PGA) was melt-blended and modified with materials such as poly(butylene adipate-co-terephthalate) (PBAT), polyhydroxyalkanoate (PHA), and additives to prepare PHA / PBAT / PGA modified particles (i.e., the aforementioned polyglycolic acid-reinforced polyester materials). PBAT was purchased from BASF (melt index 3.5 g / 10 min), grade F Blend C1200. PGA was purchased from Corbion (M w : 180,000 g / mol). The specific preparation process is as follows:

[0062] By mass, 15 parts of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3 / 4HB) (Beijing Bluepha) (M w: 300000g / mol), 10 parts of nucleating agent talc powder (Kain Chemical), 0.5 parts of epoxy chain extender styrene-methyl methacrylate-glycidyl methacrylate (ADR, BASF), 0.2 parts of anti-blocking agent erucic acid amide (Jiangxi Zhilian Plastic Technology Co., Ltd.), 0.5 parts of anti-blocking agent sodium stearate (Jiangxi Hongyuan Chemical), 0.5 parts of antioxidant antioxidant tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester (1010, BASF), 0.5 parts of light stabilizer bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate (770, BASF), 0.5 parts of ultraviolet light absorber 2-hydroxy-4-octyloxybenzophenone (UV531, BASF), 0.5 parts of anti-hydrolysis agent N,N'-bis (2,6-diisopropylphenyl) carbodiimide (Hymax 1010, Shanghai Langyi), prepared into about 4 kg of PHA mixed powder 1.

[0063] 85 parts by mass of PBAT and different parts by mass of PGA (1 part, 2 parts, 3 parts, 4 parts, 5 parts) were added to the extruder through different pellet feeders 1 and pellet feeders 2 of the extruder, and PHA mixed powder 1 was added to the extruder through another powder feeder. The extruder has 11 sections from the feed port to the die, numbered 1-11, of which the first section only serves to add materials and cannot be heated. The temperatures of sections 2-11 of the extruder are: 160°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 160°C and 160°C, respectively, and the screw speed is set at 250rpm. The PHA mixed powder 1 is fed to the first section of the twin-screw extruder with a loss-in-weight feeder provided by the extruder, and the feeding rate is: PBAT 15kg / h, PHA mixed powder 2.64kg / h. Different PGA feeding rates were used according to the added amount of PGA. The feeding rates in Examples 1 to 5 were 0.18 kg / h, 0.35 kg / h, 0.53 kg / h, 0.71 kg / h, and 0.88 kg / h, respectively.

[0064] After stable operation, the twin-screw extruder has a pressure of 10-15 bar and a torque of 40-50% (Table 1). The die of the extruder has two circular outlets with a diameter of 4 mm. After the strips are extruded from the die, they pass through a water bath cooling tank and are cut into cylindrical particles with a length of about 5 mm by a pelletizer. After vacuuming in a vacuum drying oven at 70°C for 4 hours, PHA / PBAT / PGA blended particles (Examples 1-5) are obtained and collected and packaged for later use.

[0065] [Example 6] Preparation of polyglycolic acid reinforced polyester material

[0066] Using the preparation steps of Examples 1 to 5, by mass fraction, 10 parts of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3 / 4HB) (Beijing Bluepha) (M w : 300,000 g / mol), 10 parts of nucleating agent talc powder (Kayin Chemical), 0.5 part of epoxy chain extender styrene-methyl methacrylate-glycidyl methacrylate (ADR, BASF), 0.2 part of antiblocking agent erucamide (Jiangxi Zhilian Plastic Technology Co., Ltd.), 0.5 part of antiblocking agent sodium stearate (Jiangxi Hongyuan Chemical Industry), 0.5 part of antioxidant pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (1010, BASF), 0.5 part of light stabilizer bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (770, BASF), 0.5 part of ultraviolet absorber 2-hydroxy-4-n-octyloxybenzophenone (UV531, BASF), 0.5 part of hydrolysis inhibitor N,N'-bis(2,6-diisopropylphenyl)carbodiimide (Hymax1010, Shanghai Langyi) were formulated into about 4 kg of PHA mixed powder 2.

[0067] According to the mass fraction, 90 parts of PBAT and 5 parts of PGA were respectively added to the extruder through different pellet feeders 1 and pellet feeder 2 of the extruder, and the PHA mixed powder 2 was added to the extruder through the powder feeder. The feeding speeds were: 15 kg / h for PBAT, 1.67 kg / h for PHA mixed powder 2, and 0.83 kg / h for PGA. Other processing conditions were controlled to be the same as those in Examples 1 to 5.

[0068] After stable operation, the pressure of the twin-screw extrusion was 15 bar and the torque was 48%. There were two circular outlets with a diameter of 4 mm each on the die equipped with this extruder. After the sample strip was extruded from the die, it passed through a water bath cooling tank and was cut into cylindrical particles with a length of about 5 mm by a pelletizer. After vacuum pumping for 4 h in a 70 °C vacuum drying oven, PHA / PBAT / PGA blend particles were obtained and collected and stored for later use.

[0069]

Example 7

[0070] Using the preparation steps of Examples 1 to 5, by mass fraction, 40 parts of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3 / 4HB) (Beijing Bluepha) (M w: 300000 g / mol), 10 parts of nucleating agent talcum powder (Kayin Chemical Industry), 0.5 part of epoxy chain extender styrene-methyl methacrylate-glycidyl methacrylate (ADR, BASF), 0.2 part of antiblocking agent erucamide (Jiangxi Zhilian Plastic Chemical Technology Co., Ltd.), 0.5 part of antiblocking agent sodium stearate (Jiangxi Hongyuan Chemical Industry), 0.5 part of antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (1010, BASF), 0.5 part of light stabilizer bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (770, BASF), 0.5 part of ultraviolet absorber 2-hydroxy-4-n-octyloxybenzophenone (UV531, BASF), 0.5 part of hydrolysis resistance agent N,N'-bis(2,6-diisopropylphenyl)carbodiimide (Hymax1010, Shanghai Langyi), and about 4 kg of PHA mixed powder 2 was prepared.

[0071] According to the mass parts of the obtained mixed powder, 60 parts of PBAT and 5 parts of PGA were respectively added to the extruder through different pellet feeders 1 and pellet feeder 2 of the extruder, and the PHA mixed powder 2 was added to the extruder through the powder feeder. The feeding speeds were: 10 kg / h for PBAT, 6.67 kg / h for PHA mixed powder 2, and 0.83 kg / h for PGA. Other processing conditions were controlled to be the same as those in Examples 1 to 5.

[0072] After stable operation, the pressure of the twin-screw extrusion was 23 bar and the torque was 58%. There were two circular outlets with a diameter of 4 mm each on the die equipped with the extruder. After the sample strip was extruded from the die, it passed through a water bath cooling tank and was cut into cylindrical particles with a length of about 5 mm by a pelletizer. After vacuum pumping for 4 h in a 70 °C vacuum drying oven, PHA / PBAT / PGA blend particles were obtained and collected and stored for later use.

[0073]

Comparative Example 1-3

[0074] The preparation processes of Comparative Example 1, Comparative Example 2 and Comparative Example 3 were the same as those of Example 1, Example 6 and Example 7 respectively. The difference was that PGA was not added in Comparative Examples 1 to 7. The specific processing parameters are shown in Table 1, and the prepared particles were named PHA / PBAT modified particles.

[0075] Table 1. Processing Parameters of Examples 1 to 7 and Comparative Examples 1 to 3

[0076]

[0077]

Comparative Example 4

[0078] In a co-rotating twin-screw extruder (screw diameter 25 mm, L / D = 56) from Krauss Maffei, Germany, polylactic acid PLA was melt blended and modified with PBAT, PHA, and additives to prepare PHA / PBAT / PLA modified particles. PBAT was purchased from BASF, brand F Blend C1200. PLA was purchased from NatureWorks. 15 parts by weight of poly 3-hydroxybutyrate / 4-hydroxybutyrate (P3 / 4HB) (Beijing Blue Crystal) (M w : 300000g / mol), 10 parts of nucleating agent talc powder (Kain Chemical), 0.5 parts of epoxy chain extender styrene-methyl methacrylate-glycidyl methacrylate (ADR, BASF), 0.2 parts of anti-blocking agent erucic acid amide (Jiangxi Zhilian Plastic Technology Co., Ltd.), 0.5 parts of anti-blocking agent sodium stearate (Jiangxi Hongyuan Chemical), 0.5 parts of antioxidant tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester (1010, BASF), 0.5 parts of light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (770, BASF), 0.5 parts of ultraviolet light absorber 2-hydroxy-4-octyloxybenzophenone (UV531, BASF), 0.5 parts of anti-hydrolysis agent N,N'-bis(2,6-diisopropylphenyl)carbodiimide (Hymax1010, Shanghai Langyi), prepared into about 4 kg of PHA mixed powder 3.

[0079] 85 parts by mass of PBAT and 5 parts of PLA were added to the extruder through different pellet feeders 1 and pellet feeder 2 of the extruder, and PHA mixed powder 3 was added to the extruder through the powder feeder. The extruder has 11 sections from the feed port to the die, numbered 1-11, of which the first section only serves to add materials and cannot be heated. The temperatures of sections 2-11 of the extruder are 160°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 160°C and 160°C, respectively, and the screw speed is set at 250rpm. The PHA mixed powder 2 was fed to the first section of the twin-screw extruder using the loss-in-weight feeder provided by the extruder, and the feeding speed was: 15kg / h for PBAT, 5.3kg / h for PHA mixed powder 3, and 0.88kg / h for PLA. The prepared particles were named PHA / PBAT / PLA modified particles.

[0080] [Example 8] DSC test

[0081] The PHA / PBAT / PGA modified particles obtained from the above Examples 1-7, the PHA / PBAT modified particles obtained from Comparative Examples 1-3, and the PHA / PBAT / PLA modified particles obtained from Comparative Example 4 were subjected to differential scanning calorimetry (DSC) tests. The crystallization temperature (Tc), crystallization enthalpy (ΔH c ) during the cooling process, and the melting temperature (T m ), melting enthalpy (ΔH m ) during the second heating process are shown in Table 2.

[0082] Table 2. DSC test results of Comparative Examples 1-4 and Examples 1-7

[0083] <![CDATA[T c (℃)]]> <![CDATA[△H c (J / g)]]> <![CDATA[T m (℃)]]> <![CDATA[△H m (J / g)]]> Comparative Example 1 99.3 11.3 125.7 3.4 Comparative Example 2 90.3 10.3 122.8 4.1 Comparative Example 3 95.6 8.1 125.9 4.7 Comparative Example 4 84.3 7.7 121.5 4.8 Example 1 91.0 9.9 124.6 4.5 Example 2 90.1 8.9 125.4 5.1 Example 3 90.7 9.4 124.9 5.5 Example 4 91.3 9.7 125.2 5.0 Example 5 91.7 9.6 124.8 5.5 Example 6 91.2 9.5 124.4 5.3 Example 7 83.4 7.9 122.9 4.5

[0084] As shown in Table 2, when the addition of PGA increased, the overall crystallization enthalpy of the PHA / PBAT / PGA modified particles decreased, the melting enthalpy increased slightly, and the crystallization peak became narrower, indicating that the introduction of PGA could promote the crystallization process of PHA / PBAT and accelerate the crystallization rate. At the same time, in the first heating curve of the PHA / PBAT / PGA modified particles with Figure 1A , it can be seen that as the addition amount of PGA increased, the melting peak of PBAT in the first heating curve changed little. At the position of 210 °C, as PGA was added to more than 3%, the melting peak of PGA gradually appeared. In the second heating curve of Figure 1B , it can be seen that the melting peak belonging to PGA disappeared, indicating that the compatibility between PGA and PHA / PBAT in the PHA / PBAT / PGA modified particles obtained from Examples 1-5 was good.

[0085]

Example 9

[0086] The PHA / PBAT / PGA modified particles obtained from the above Examples 1-7, the PHA / PBAT modified particles obtained from Comparative Examples 1-2, and the PHA / PBAT / PLA modified particles obtained from Comparative Example 3 were processed into degradable mulch films. The specific processing parameters and thickness are shown in Table 3.

[0087] Table 3. Blown film parameters of mulch film

[0088]

[0089] Blow the film on the HAAKE TM Rheomex OS single-screw extruder manufactured by Thermo Fisher Scientific Inc. in the United States. The screw diameter of this extruder is 19 mm, the length-diameter ratio is 25, and it is equipped with a 3:1 standard metering screw. This single-screw extruder is controlled by the HAAKE TM PolyLab TM OS torque rheometer platform. The extruder has a total of four heating zones, numbered 1-4 from the feed port to the outlet, and is configured with a blown film die with a die diameter of 19.5 mm and a die gap of 0.5 mm with heating function. The screw speed is set to 50 rpm, and the temperatures of each zone are set to: 50 °C, 150 °C, 155 °C, and 150 °C. Subsequently, a degradable plastic film for agricultural use is made through cooling, shaping, stretching, and winding.

[0090]

Example 10

[0091] Perform the tensile property test of the film sample parallel to the stretching direction (MD) on the plastic film for agricultural use prepared in Example 9 according to the test steps described above. The obtained results are shown in Figures 2 to 4 .

[0092] As Figures 2 to 4 shown, after adding PGA in Examples 1-6, the elongation at break and strength of the obtained plastic film for agricultural use are significantly improved. Compared with the plastic film for agricultural use without adding PGA in Comparative Example 1, the strength of the plastic film for agricultural use with 5% PGA added in Example 5 increased from 20 Mpa to 31 Mpa ( Figure 2 ), and its elongation at break increased from 415% to 523% ( Figure 3 ). Figure 4 In , compared with Comparative Examples 1-3, the modulus of the plastic film for agricultural use in Examples 1-6 increased significantly. After adding 5% PGA in Example 5, the modulus of the PBAT / PHA / PGA plastic film for agricultural use increased from 42 Mpa (Comparative Example 1) to 108 Mpa, and the modulus increased by 120% compared with the PBAT / PHA plastic film for agricultural use without addition (Comparative Example 1). Compared with the PHA / PBAT plastic film for agricultural use in Comparative Example 2, the comprehensive mechanical properties of the PHA / PBAT / PGA plastic film for agricultural use with 5% PGA added in Example 6 also increased to some extent. The strength increased from 21 Mpa to 33 Mpa, the elongation increased from 488% to 527%, and the modulus increased from 66 Mpa to 124 Mpa. Compared with the PHA / PBAT / PLA plastic film for agricultural use modified with 5% PLA in Comparative Example 3, the PHA / PBAT / PGA plastic film for agricultural use with 5% PGA in Example 5 has more excellent comprehensive mechanical properties.

[0093]

Example 11

[0094] The plastic film prepared in Example 9 was cut into strips according to the standard of QB / T 1130-91, and its right-angle tearing performance was tested. The relationship between the right-angle tearing force (N) and the PGA content is as follows Figure 5 shown. As Figure 5 shown, the right-angle tearing strength of the PHA / PBAT plastic film (Comparative Example 1) is about 131 kN / m. After adding PGA, the right-angle tearing strength of the PGA / PBAT / PHA plastic films obtained in Examples 1 to 5 is significantly improved. When 4% PGA is added, its right-angle tearing strength is increased to 208 kN / m, which is 1.5 times that of the plastic film without adding PGA (Comparative Example 1). In addition, in Comparative Example 3, the right-angle tearing strength of the PHA / PBAT plastic film with 40% PHA content is only 68 kN / m, while after adding 5% PGA, the right-angle tearing strength in Example 7 is increased to 97 kN / m. It can be seen that in the present invention, by introducing an appropriate amount of PGA into the PHA / PBAT plastic film, the tear resistance of the PHA plastic film can be effectively improved, making it easier to lay the film and having a longer service life.

Claims

1. A polyglycolic acid reinforced polyester material, comprising: a base material and a reinforcing material, wherein the base material comprises a polyhydroxyalkanoate and a biodegradable polyester, the reinforcing material is polyglycolic acid, and the biodegradable polyester is polybutylene adipate / terephthalate; based on 100 parts by mass of the total weight of the base material, the reinforcing material is 1 to 5 parts, the polyhydroxyalkanoate is 1 to 30 parts, and the biodegradable polyester is 70 to 99 parts.

2. The polyglycolic acid reinforced polyester material according to claim 1, characterized in that the weight-average molecular weight of the polyglycolic acid is 30,000 to 500,000 g / mol; and / or, the weight-average molecular weight of the biodegradable polyester is 10,000 to 180,000 g / mol; and / or, the weight-average molecular weight of the polyhydroxyalkanoate is 50,000 to 800,000 g / mol; and / or, the polyhydroxyalkanoate has a structural unit shown in one of formulas (I) to (III): Formula (I) In formula (I), R 1 is H or a C1-C16 hydrocarbon group, and n is a positive integer between 1 and 10,000; Formula (II) In formula (II), R 2 and R 3 are different and are H or a C1-C16 hydrocarbon group; m and n are positive integers between 1 and 10,000; Formula (III) In formula (III), R 4 , R 5 are different and are H or a C1-C16 hydrocarbon group; m and n are positive integers between 1 and 10,000.

3. The polyglycolic acid reinforced polyester material according to claim 2, characterized in that the weight-average molecular weight of the polyglycolic acid is 50,000 to 400,000 g / mol; and / or, the weight-average molecular weight of the biodegradable polyester is 50,000 to 150,000 g / mol; and / or, the weight-average molecular weight of the polyhydroxyalkanoate is 80,000 to 500,000 g / mol; and / or, the polyhydroxyalkanoate is selected from at least one of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

4. The polyglycolic acid reinforced polyester material according to claim 1, characterized in that the polyglycolic acid reinforced polyester material further comprises an auxiliary agent.

5. The polyglycolic acid reinforced polyester material according to claim 4, characterized in that the auxiliary agent comprises at least one of a nucleating agent, a chain extender, an antiblocking agent, and a stabilizer.

6. The polyglycolic acid reinforced polyester material according to claim 5, characterized in that the nucleating agent is selected from at least one of nanocrystalline cellulose, talcum powder, silica, and plate-like calcium carbonate; and / or, the chain extender is selected from at least one of polyfunctional isocyanates, polyfunctional epoxides, and polyfunctional polymers; and / or, the antiblocking agent is selected from at least one of oleic acid amide, erucic acid amide, stearic acid amide, and sodium stearate; and / or, the stabilizer is selected from at least one of ultraviolet absorbers, light stabilizers, antioxidants, and hydrolysis-resistant agents; and / or, based on 100 parts by mass of the total amount of the base material, the nucleating agent is 0.02 to 30 parts, the chain extender is 0.01 to 6 parts, the antiblocking agent is 0.02 to 10 parts, and the stabilizer is 0.03 to 30 parts.

7. The polyglycolic acid reinforced polyester material according to claim 6, characterized in that The chain extender is selected from at least one of hexamethylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, and a terpolymer of styrene-methyl methacrylate-glycidyl methacrylate; and / or, The ultraviolet absorber is selected from at least one of benzotriazole compounds, benzoxazine compounds, benzotriazole compounds, aniline compounds, triazine compounds, and benzophenone compounds. The light stabilizer is selected from at least one of hindered amine light stabilizers and hindered phenol light stabilizers. The antioxidant is selected from at least one of hindered phenol antioxidants and phosphite antioxidants. The anti-hydrolysis agent is selected from carbodiimide compounds; and / or, Based on 100 parts by mass of the total amount of the base material, the nucleating agent is 1 to 20 parts, the chain extender is 0.05 to 2 parts, the antiblocking agent is 0.05 to 5 parts, and the stabilizer is 0.03 to 20 parts.

8. A method for preparing the polyglycolic acid-reinforced polyester material according to any one of claims 1 to 7, comprising mixing components including the polyhydroxyalkanoate, the biodegradable polyester, polyglycolic acid, and optionally added additives, and then melt-extruding to obtain the polyglycolic acid-reinforced polyester material.

9. According to the preparation method of claim 8, characterized in that, the preparation method includes: Step 1, premix the polyhydroxyalkanoate with optionally added additives to form a premixed powder; Step 2, mix the biodegradable polyester and polyglycolic acid, add the premixed powder of Step 1, and after melt-extrusion, cooling, and pelletizing, obtain the polyglycolic acid-reinforced polyester material.

10. According to the preparation method of claim 9, characterized in that, the temperature of the melt-extrusion is 50 to 350 °C; and / or, the screw speed of the melt-extrusion is 5 to 500 rpm.

11. According to the preparation method of claim 10, characterized in that, the temperature of the melt-extrusion is 50 to 300 °C; and / or, the screw speed of the melt-extrusion is 50 to 300 rpm.

12. A tear-resistant biodegradable mulch film comprising the polyglycolic acid-reinforced polyester material according to any one of claims 1 to 7, or comprising the polyglycolic acid-reinforced polyester material obtained by the preparation method according to any one of claims 8 to 11.

13. According to the tear-resistant biodegradable mulch film of claim 12, characterized in that, the thickness of the tear-resistant biodegradable mulch film is 4 to 30 μm; and / or, the right-angle tear strength of the tear-resistant biodegradable mulch film is 50 to 270 kN / m; and / or, the breaking strength of the tear-resistant biodegradable mulch film is 10 to 40 MPa; and / or, the elongation at break of the tear-resistant biodegradable mulch film is 300 to 1000%; and / or, the modulus of the tear-resistant biodegradable mulch film is 60 to 200 MPa.

14. According to the tear-resistant biodegradable mulch film of claim 13, characterized in that, the thickness of the tear-resistant biodegradable mulch film is 5 to 25 μm; and / or, the right-angle tear strength of the tear-resistant biodegradable mulch film is 100 to 250 kN / m; and / or, The breaking strength of the tear-resistant degradable plastic film is 15-35 MPa; and / or, The elongation at break of the tear-resistant degradable plastic film is 500-800%; and / or, The modulus of the tear-resistant degradable plastic film is 60-150 MPa.

15. A method for preparing the tear-resistant degradable plastic film according to any one of claims 12 to 14, comprising melting and extruding the polyglycolic acid-reinforced polyester material, blowing the film, and cooling to obtain the tear-resistant degradable plastic film.

16. According to the method for preparing the tear-resistant degradable plastic film according to claim 15, the melting and extrusion is carried out by a single-screw extruder.

17. According to the preparation method of claim 16, characterized in that the temperature of the melting and extrusion is 150-300 °C; and / or, the screw rotation speed of the single-screw extruder is 5-200 rpm.

18. According to the preparation method of claim 17, characterized in that the temperature of the melting and extrusion is 160-250 °C; and / or, the screw rotation speed of the single-screw extruder is 10-150 rpm.

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