A container with both high barrier properties and high flexibility and a preparation method thereof

Abstract

The present invention belongs to the technical field of packaging, and discloses a container with both high barrier properties and high flexibility and a preparation method thereof. The container includes a container matrix and an aluminum film layer, and the aluminum film layer is deposited on the outer surface of the container matrix. The raw materials for preparing the container matrix include: PLA, PLA-PCL block copolymer, branched PLA, P34HB, soybean oil polyol and organotin catalyst. Through the combined action of the above raw materials, the present invention has excellent flexibility, blow molding processability and compatibility. The container matrix obtained by forming the raw materials can realize uniform coating on the outer surface of the container matrix to form an aluminum film layer, so that the container has both high barrier properties and high flexibility, and has excellent ductility, tensile strength, impact strength and biodegradability; the aluminum film layer of the container of the present invention will not crack during tensile deformation below 20%, and the barrier properties will not be affected.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging, and particularly relates to a container with both high barrier properties and high flexibility and a preparation method thereof. Background Art

[0002] In packaging products, especially in containers for holding liquids, plastic materials such as PE, PP, PET, etc. are still widely used for preparation. The above-mentioned plastic materials derived from petroleum-based have excellent processability, good mechanical properties, and some materials such as PET also have superior barrier properties. Although they have excellent properties, these plastic materials are difficult to degrade, bringing a series of environmental problems. Finding packaging materials that also have excellent properties and can be completely degraded is still the direction of people's efforts.

[0003] Among the degradable materials for preparing containers for holding liquids, PLA (polylactic acid) is usually used as the raw material. PLA is easy to process, has high strength and processability, and is suitable for different processing methods; however, PLA has its natural disadvantages, mainly being relatively brittle and easily cracking under impact. Other biomass composite materials such as PLA / PBAT (polybutylene adipate terephthalate), PLA / PCL (polycaprolactone), etc. cannot achieve good blow molding due to problems such as poor blow molding processability, compatibility, and flexibility, resulting in poor flexibility of the prepared containers and poor water and oxygen barrier capabilities, restricting the use of the containers for packaging certain special contents such as wines or other beverages containing gas. In addition, the flexibility and barrier properties of the containers often conflict with each other. When the flexibility is improved, the barrier property will decrease, and it is difficult to have both high flexibility and high barrier properties at the same time.

[0004] Therefore, there is an urgent need to provide a container with both high barrier properties and high flexibility to meet the actual market demand. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides a container and a preparation method thereof, and the container has both high barrier properties and high flexibility.

[0006] The first aspect of the present invention provides a container, including a container matrix and an aluminum film layer, the aluminum film layer is deposited on the outer surface of the container matrix, and the preparation raw materials of the container matrix include: PLA, PLA-PCL block copolymer, branched PLA, P34HB, soybean oil polyol, and organotin catalyst.

[0007] According to some embodiments of the present invention, by mass parts, the raw materials for preparing the container matrix include: 33 - 52 parts of PLA, 16 - 28 parts of PLA-PCL block copolymer, 3 - 5 parts of branched PLA, 24 - 38 parts of P34HB, 4 - 12 parts of soybean oil polyol, and 0.5 - 1 part of organotin catalyst.

[0008] According to some embodiments of the present invention, the raw materials for preparing the container matrix further include: a flow modifier and an antioxidant.

[0009] According to some embodiments of the present invention, by mass parts, the raw materials for preparing the container matrix further include: 1 - 3 parts of flow modifier and 0.2 - 0.5 parts of antioxidant.

[0010] According to some embodiments of the present invention, the PLA-PCL block copolymer has a weight-average molecular weight of 40,000 - 100,000, and the molar ratio of PLA to PCL is (0.5 - 1.5):1. The PLA-PCL block copolymer can be prepared by a conventional preparation method; for example, polylactic acid and polycaprolactone with a certain molecular weight are selected as reaction raw materials, mixed with hexamethylene diisocyanate (HDI) and an organotin catalyst, and subjected to a chain extension reaction to obtain; wherein, HDI is used as a chain extender, and the addition amount is 1 - 2% of the mass of the reaction raw materials, and the addition amount of the organotin catalyst is 0.1 - 0.3% of the mass of the reaction raw materials.

[0011] According to some embodiments of the present invention, the branched PLA has a weight-average molecular weight of 82,000 - 164,000. Preferably, the branched PLA has a weight-average molecular weight of 134,000 - 142,000.

[0012] Specifically, the branched PLA is 4-arm branched polylactic acid, and its molecular structural formula is as follows:

[0013]

[0014] Among them, R represents CH or C2H3, R' represents an alkyl group, a = 200 - 400, b = 200 - 400, c = 250 - 400, d = 300 - 650. Preferably, R' represents a C1 - C4 alkyl group.

[0015] According to some embodiments of the present invention, the P34HB is poly-3-hydroxybutyrate 4-hydroxybutyrate, and its molecular structural formula is as follows:

[0016]

[0017] Among them, n = 200 - 500, m = 60 - 140.

[0018] According to different values of n and m, the present invention can achieve differentiated mechanical properties and barrier properties. For example, increasing the value of m can improve the flexibility of the material; increasing the value of n can improve the strength of the material. Preferably, n = 300 - 400 and m = 100 - 140.

[0019] According to some embodiments of the present invention, the functionality of the soybean oil polyol is 4 - 4.5.

[0020] According to some embodiments of the present invention, the organotin catalyst is dibutyltin dilaurate and / or stannous octoate. The addition of the organotin catalyst in the present invention can promote the transesterification reaction between various polyesters, especially under the condition of vacuum pumping at the homogenization backend, which is beneficial to the occurrence of the transesterification reaction and further beneficial to the homogenization of the material system.

[0021] According to some embodiments of the present invention, the antioxidant includes at least one of antioxidant 1010, antioxidant BHT, antioxidant 1076, and antioxidant 168.

[0022] According to some embodiments of the present invention, a topcoat layer is provided on the outer surface of the aluminum film layer, and the components of the topcoat layer are polyacrylate and / or polyurethane.

[0023] According to some embodiments of the present invention, the thickness of the aluminum film layer is 10 - 50 μm.

[0024] According to some embodiments of the present invention, the thickness of the topcoat layer is 1 - 50 μm.

[0025] The second aspect of the present invention provides a method for preparing the above-mentioned container, including the following steps:

[0026] 1) Mix the raw materials for preparing the container substrate, extrude and pelletize to obtain pellets;

[0027] 2) Inject the pellets to obtain a container embryo;

[0028] 3) Blow-mold the container embryo to obtain a container substrate;

[0029] 4) Perform surface plasma treatment on the container substrate, and then perform magnetron sputtering coating to form an aluminum film layer on the outer surface of the container substrate to obtain the container.

[0030] According to some embodiments of the present invention, in step 1), before mixing, it further includes the step of drying the raw materials for preparing the container substrate at 120 - 140 °C for 3 - 4 h with a dehumidifying dryer.

[0031] According to some embodiments of the present invention, in step 1), the specific process of the extrusion and pelletization is as follows:

[0032] Adopt a two-stage feeding method. First, put part of the PLA, P34HB, soybean oil polyol, and organotin catalyst into the first feed port, and then put the remaining raw materials into the second material port. Among them, the first feed port is located at the initial part of the extrusion screw, and the second feed port is located at the front end of the homogenization section of the extrusion screw. The masses of PLA, P34HB, soybean oil polyol, and organotin catalyst put into the first feed port are 60-100%, 40-80%, 65-80%, and 40-60% of the total mass of the corresponding raw materials respectively.

[0033] According to some embodiments of the present invention, in the specific process of extrusion granulation, the extrusion temperature is set to 190-210°C, which gradually increases from the first feed port to the extrusion homogenization section. A vacuum extraction device is arranged at the front end of the homogenization section for vacuum extraction, and the vacuum degree during extrusion is set to 0.1-0.4 MPa; the screw speed is 200-300 rad / min, and the residence time is 0.5-1 min.

[0034] According to some embodiments of the present invention, the blow molding and surface plasma treatment processes can be completed continuously or intermittently; the surface plasma treatment and magnetron sputtering coating processes are completed continuously.

[0035] According to some embodiments of the present invention, in step 2), the injection molding conditions include:

[0036] The temperature is 220-240°C, the back pressure is 35-65 bar, and the injection time is 4-6 s.

[0037] According to some embodiments of the present invention, in step 2), in the injection molding process, a heat insulation plate with a thickness of 7-11 mm is provided between the injection mold and the injection machine template, and the exhaust depth is between 0.15-0.35 mm.

[0038] According to some embodiments of the present invention, in step 2), the thickness of the container preform is 1-10 mm.

[0039] According to some embodiments of the present invention, in step 3), the specific process of blow molding is as follows:

[0040] Put the container preform into the mold cavity, seal the mold cavity after closing the mold, perform stretching at 110-130°C, with the stretching ratio between 1.2-1.5. Blow air for the first time at a low pressure of 4-7.5 bar, then blow air for the second time at a pressure of 7.5-11.5 bar, and then blow air from the top of the stretching rod at a pressure of 5.5-10 bar to form. Finally, eject and cool at 20-30°C for 1.5-3 h to set the shape, obtaining the container substrate; among them, the radial stretching and blowing ratio is between 2.4-3.4, and the axial blowing ratio is between 1.8-2.4.

[0041] According to some embodiments of the present invention, in step 4), the specific process of the surface plasma treatment is as follows:

[0042] Place the container substrate into a plasma cleaning chamber, and use plasma with an energy of 5 - 20 eV to treat the outer surface of the container substrate.

[0043] According to some embodiments of the present invention, in step 4), the conditions for magnetron sputtering coating include:

[0044] The vacuum degree is 0.8 - 1.1×10 -2 Pa, the target - substrate distance is 55 - 80 mm, the sputtering power is 700 - 900 W, and the sputtering time is 90 - 140 s.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] (1) The container provided by the present invention, wherein the preparation raw materials of the container substrate are based on a composite system, that is, using PLA and P34HB with higher strength as the main raw materials, introducing PLA - PCL block copolymer and soybean oil polyol as soft segments, and combining with organotin catalysts to achieve polycondensation and transesterification reactions of various raw materials. The branched PLA acts as a crystallization nucleating agent and can uniform the strength in different directions and resist cracking in different directions. The above raw materials work together to have excellent flexibility, blow - molding processability and compatibility. The container substrate obtained by molding the raw materials can uniformly coat an aluminum film layer on the outer surface of the container substrate, so that the container has both high barrier properties and high flexibility at the same time. The aluminum film layer of the container of the present invention will not crack during a tensile deformation of less than 20%, and the barrier properties will not be affected.

[0047] (2) The container of the present invention has excellent ductility, tensile strength, impact strength and water - oxygen barrier properties, and can be completely degraded under composting. Among them, the elongation at break is 180 - 350%, the tensile strength is 22 - 33 MPa, the notched impact strength is 7 - 11 Kg.cm / cm, the oxygen transmission rate of the container is 80 - 150 cm 3 / (m 2 ·24h·0.1MPa), and the water vapor transmission rate is 50 - 130 g / (m 2 ·24hr·MPa); under the condition of soil composting at 25°C, the time required for the container to be completely degraded is 17 - 20 weeks. Specific embodiments

[0048] In order to make those skilled in the art more clearly understand the technical solutions of the present invention, the following examples are listed for illustration. It should be noted that the following examples do not limit the scope of protection required by the present invention.

[0049] Unless otherwise specified, the raw materials, reagents, and devices used in the following examples can be obtained from conventional commercial channels or can be obtained by existing known methods. Unless otherwise specified, the test or testing methods are conventional methods in the art.

[0050] Example 1

[0051] A container includes a container substrate and an aluminum film layer deposited on the outer surface of the container substrate. By mass fraction, the raw materials for preparing the container substrate include: 48 parts of PLA, 20 parts of low molecular weight PLA-PCL, 4.5 parts of branched PLA, 36 parts of P34HB, 10 parts of soybean oil polyol, 0.8 part of dibutyltin dilaurate, 1 part of flow modifier, and 0.5 part of antioxidant 1010.

[0052] The P34HB used in this example is poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and its molecular structural formula is as follows:

[0053]

[0054] Among them, n = 360 and m = 120.

[0055] The low molecular weight PLA-PCL used in this example is a block copolymer of polylactic acid and polycaprolactone, with a weight average molecular weight of 92000, and the molar ratio of PLA to PCL is 1.2.

[0056] The branched PLA used in this example is 4-arm branched polylactic acid, which can be formed by using a trifunctional monomer as the reaction starting point and through polycondensation in the synthesis section or processing section. Its weight average molecular weight is 134000, and its molecular structural formula is as follows:

[0057] R is CH, R' is C3H7, a = 260, b = 340, c = 300, d = 580.

[0058] The functionality of the soybean oil polyol used in this example is 4.5, and its weight average molecular weight is 12000.

[0059] The flow modifier used in this example is the CJ-2 flow modifier purchased from Guangzhou Chuanju Chemical Technology Co., Ltd.

[0060] The preparation method of the container in this example includes the following steps:

[0061] 1) The raw materials for preparing the container substrate are dried in a dehumidifying dryer at 130°C for 3.5 hours. After taking them out, they are uniformly mixed by a high-speed mixer and then added into an extruder for extrusion granulation to obtain pellets. Among them, extrusion granulation adopts two-stage feeding. The first feeding port is located at the initial part of the extrusion screw, and the second feeding port is located at the front end of the homogenization section of the extrusion screw. First, part of PLA (70% of the total mass of PLA), P34HB (60% of the total mass of P34HB), soybean oil polyol (75% of the total mass of soybean oil polyol), and dibutyltin dilaurate (55% of the total mass of dibutyltin dilaurate) are put into the first feeding port, and then the remaining raw materials are put into the second material port. The extrusion temperature is set at 190 - 210°C, and the five sections are 190°C, 195°C, 200°C, 205°C, and 210°C respectively. A vacuum extraction device is set at the front end of the homogenization section for vacuum extraction. The vacuum degree during extrusion is set at 0.25 MPa, the screw speed is 280 rad / min, and the residence time is 0.8 min.

[0062] 2) The pellets are put into an injection molding machine and injection molded at 230°C. The back pressure is set at 55 bar, and the injection time is 4 seconds to obtain a container embryo with a thickness of 3.4 mm. Among them, a heat insulation board with a thickness of 9 mm is provided between the injection mold and the injection molding machine template, and the exhaust depth is 0.25 mm.

[0063] 3) The container embryo is put into the mold cavity. After closing the mold, the mold cavity is sealed and stretched at 120°C. The stretching ratio is 1.3. The first blowing is carried out at a low pressure of 6.3 bar, the second blowing is carried out at a pressure of 11.2 bar, and then the blowing is carried out from the top of the stretching rod at a pressure of 8.0 bar for forming. Finally, it is ejected and cooled at 22°C for 1.5 hours for shaping to obtain the container substrate. Among them, the radial stretching and blowing ratio is 3.2, and the axial blowing ratio is 2.3 to obtain the container substrate.

[0064] 4) The container substrate is placed in a plasma cleaning chamber, and the outer surface of the container substrate is treated with plasma with an energy of 20 eV. Then it is put into a magnetron sputtering coating device. The vacuum degree is set at 0.9×10 -2 Pa. Aluminum metal is used as the target material, the target-substrate distance is 70 mm, the sputtering power is 850 W, and the sputtering time is 120 s for magnetron sputtering coating. An aluminum film layer is deposited on the outer surface of the container substrate to obtain the container.

[0065] The wall thickness of the container is 340 μm, and the thickness of the aluminum film layer is 25 μm.

[0066] Example 2

[0067] A container includes a container matrix and an aluminum film layer deposited on the outer surface of the container matrix. By mass fraction, the raw materials for preparing the container matrix include: 46 parts of PLA, 18 parts of low molecular weight PLA-PCL, 3.5 parts of branched PLA, 32 parts of P34HB, 8 parts of soybean oil polyol, 0.56 parts of dibutyltin dilaurate, 2 parts of flow modifier, and 0.4 parts of antioxidant 1010.

[0068] The P34HB used in this example is poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and its molecular structural formula is as follows:

[0069]

[0070] Among them, n = 330 and m = 140.

[0071] The low molecular weight PLA-PCL used in this example is a block copolymer of polylactic acid and polycaprolactone, with a weight average molecular weight of 68000, and the molar ratio of PLA to PCL is 1.2.

[0072] The branched PLA used in this example is 4-arm branched polylactic acid, which can be formed by using a trifunctional monomer as the reaction starting point and through polycondensation in the synthesis section or the processing section. Its weight average molecular weight is 142000, and its molecular structural formula is as follows:

[0073] R is C2H3, R' is C3H7, a = 280, b = 380, c = 300, and d = 600.

[0074] The functionality of the soybean oil polyol used in this example is 4.5, and its weight average molecular weight is 12000.

[0075] The flow modifier used in this example is the HyPerC181 flow modifier purchased from Hubei Hyperbranched New Materials Technology Co., Ltd.

[0076] The preparation method of the container in this example includes the following steps:

[0077] 1) The raw materials for preparing the container substrate are dried in a dehumidifying dryer at 130°C for 3 hours. After taking them out, they are uniformly mixed by a high-speed mixer and then added into an extruder for extrusion granulation to obtain granular materials. Among them, the extrusion granulation adopts two-stage feeding. The first feeding port is located at the initial part of the extrusion screw, and the second feeding port is located at the front end of the homogenization section of the extrusion screw. First, part of PLA (75% of the total mass of PLA), P34HB (50% of the total mass of P34HB), soybean oil polyol (70% of the total mass of soybean oil polyol), and dibutyltin dilaurate (50% of the total mass of dibutyltin dilaurate) are put into the first feeding port, and then the remaining raw materials are put into the second material port. The extrusion temperature is set at 190 - 210°C, and the five sections are 190°C, 195°C, 200°C, 205°C, and 210°C respectively. A vacuum pumping device is set at the front end of the homogenization section for vacuum pumping. The vacuum degree during extrusion is set at 0.3 MPa, the screw speed is 250 rad / min, and the residence time is 0.6 min;

[0078] 2) The granular materials are put into an injection molding machine and injection molded at 230°C. The back pressure is set at 50 bar, and the injection time is 5 seconds to obtain a container embryo with a thickness of 3.8 mm. Among them, a heat insulation board with a thickness of 10 mm is provided between the injection mold and the injection molding machine template, and the exhaust depth is 0.3 mm;

[0079] 3) The container embryo is added into the mold cavity. After closing the mold, the mold cavity is sealed and stretched at 125°C. The stretching ratio is 1.4. The first blowing is carried out at a low pressure of 5.5 bar, the second blowing is carried out at a pressure of 10.5 bar, and then the blowing is carried out from the top of the stretching rod at a pressure of 8.5 bar for molding. Finally, it is ejected and cooled at 22°C for 1.5 hours for shaping to obtain the container substrate. Among them, the radial stretching and blowing ratio is 2.8, and the axial blowing ratio is 2.1 to obtain the container substrate;

[0080] 4) The container substrate is placed into a plasma cleaning chamber, and the outer surface of the container substrate is treated with plasma with an energy of 15 eV. Then it is put into a magnetron sputtering coating device. The vacuum degree is set at 1.0×10 -2 Pa. Aluminum metal is used as the target material, the target-substrate distance is 65 mm, the sputtering power is 800 W, and the sputtering time is 130 s for magnetron sputtering coating. An aluminum film layer is deposited on the outer surface of the container substrate to obtain the container.

[0081] The wall thickness of the container is 320 μm, and the thickness of the aluminum film layer is 28 μm.

[0082] Example 3

[0083] A container includes a container matrix and an aluminum film layer deposited on the outer surface of the container matrix. By mass fraction, the raw materials for preparing the container matrix include: 46 parts of PLA, 22 parts of low molecular weight PLA-PCL, 4.2 parts of branched PLA, 34.5 parts of P34HB, 9.6 parts of soybean oil polyol, 0.8 parts of stannous octoate, 3 parts of flow modifier, and 0.5 parts of antioxidant BHT.

[0084] The P34HB used in this example is poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and its molecular structural formula is as follows:

[0085]

[0086] Among them, n = 440 and m = 80.

[0087] The low molecular weight PLA-PCL used in this example is a block copolymer of polylactic acid and polycaprolactone, with a weight average molecular weight of 68000, and the molar ratio of PLA to PCL is 1.2.

[0088] The branched PLA used in this example is 4-arm branched polylactic acid, which can use a trifunctional monomer as the reaction starting point and be formed by polycondensation in the synthesis section or the processing section. Its weight average molecular weight is 142000, and its molecular structural formula is as follows:

[0089] R is C2H3, R' is C3H7, a = 280, b = 380, c = 300, and d = 600.

[0090] The functionality of the soybean oil polyol used in this example is 4.5, and its weight average molecular weight is 12000.

[0091] The flow modifier used in this example is the HyPerC181 flow modifier purchased from Hubei Hyperbranched New Materials Technology Co., Ltd.

[0092] The preparation method of the container in this example includes the following steps:

[0093] 1) The raw materials for preparing the container substrate are dried in a dehumidifying dryer at 130 °C for 3 hours. After taking them out, they are evenly mixed by a high-speed mixer, and then added into an extruder for extrusion granulation to obtain granular materials. Among them, the extrusion granulation adopts a two-stage feeding method. The first feeding port is located at the initial part of the extrusion screw, and the second feeding port is located at the front end of the homogenization section of the extrusion screw. First, part of PLA (85% of the total mass of PLA), P34HB (40% of the total mass of P34HB), soybean oil polyol (65% of the total mass of soybean oil polyol), and stannous octoate (50% of the total mass of stannous octoate) are put into the first feeding port, and then the remaining raw materials are put into the second material port. The extrusion temperature is set at 190 - 210 °C, and the 5 sections are 190 °C, 195 °C, 200 °C, 205 °C, and 210 °C respectively. A vacuum pumping device is set at the front end of the homogenization section for vacuum pumping. The vacuum degree during extrusion is set at 0.3 MPa, the screw speed is 260 rad / min, and the residence time is 0.8 min.

[0094] 2) The granular materials are put into an injection molding machine and injection molded at 230 °C. The back pressure is set at 60 bar, and the injection time is 5.5 seconds to obtain a container blank with a thickness of 4 mm. Among them, a heat insulation board with a thickness of 9 mm is provided between the injection mold and the injection molding machine template, and the exhaust depth is 0.3 mm.

[0095] 3) The container blank is put into the mold cavity. After closing the mold, the mold cavity is sealed, and it is stretched at 125 °C. The stretching ratio is 1.3. The first blowing is carried out at a low pressure of 6.2 bar, then the second blowing is carried out at a pressure of 9.5 bar, and then the blowing is carried out from the top of the stretching rod at a pressure of 9.0 bar for forming. Finally, it is ejected and cooled at 22 °C for 2 hours for shaping to obtain the container substrate. Among them, the radial stretching and blowing ratio is 2.6, and the axial blowing ratio is 2.2 to obtain the container substrate.

[0096] 4) The container substrate is placed in a plasma cleaning chamber, and the outer surface of the container substrate is treated with plasma with an energy of 18 eV. Then it is put into a magnetron sputtering coating device. The vacuum degree is set at 1.1×10 -2 Pa. Aluminum metal is used as the target material, the target-substrate distance is 80 mm, the sputtering power is 900 W, and the sputtering time is 120 s for magnetron sputtering coating. An aluminum film layer is deposited on the outer surface of the container substrate to obtain the container.

[0097] The wall thickness of the container is 322 μm, and the thickness of the aluminum film layer is 26 μm.

[0098] Example 4

[0099] The difference between Example 4 and Example 1 is that after completing the magnetron sputtering coating process in Example 4, a 15-μm polyurethane topcoat is sprayed on the surface of the aluminum film layer.

[0100] Example 5

[0101] The difference between Example 5 and Example 1 is that Example 5 adjusted the dosages of the raw materials for preparing the container matrix, specifically: 33 parts of PLA, 28 parts of low molecular weight PLA-PCL, 5 parts of branched PLA, 32 parts of P34HB, 12 parts of soybean oil polyol, 0.7 part of dibutyltin dilaurate, 2 parts of flow modifier, and 0.4 part of antioxidant 1010. The preparation method of the container is the same as that of Example 1.

[0102] Example 6

[0103] The difference between Example 6 and Example 1 is that Example 6 adjusted the dosages of the raw materials for preparing the container matrix, specifically: 52 parts of PLA, 16 parts of low molecular weight PLA-PCL, 3 parts of branched PLA, 32 parts of P34HB, 5 parts of soybean oil polyol, 0.6 part of dibutyltin dilaurate, 3 parts of flow modifier, and 0.5 part of antioxidant 1010. The preparation method of the container is the same as that of Example 1.

[0104] Example 7

[0105] The difference between Example 7 and Example 1 is that Example 7 adjusted the parameters in step 3) of the container preparation method, specifically: 3) Put the container embryo into the mold cavity, seal the mold cavity after closing the mold, carry out stretching at 125°C, the stretching ratio is 1.5, carry out the first blowing with a low pressure of 7.5 bar, then carry out the second blowing with a pressure of 11.0 bar, and then blow air from the top of the stretching rod with a pressure of 10.0 bar to form, and finally eject and cool at 22°C for 2 hours to set, obtaining the container matrix; among them, the radial stretching and blowing ratio is 3.2, and the axial blowing ratio is 1.8, obtaining the container matrix; for other steps, the parameters are the same as those of Example 1.

[0106] Example 8

[0107] The difference between Example 8 and Example 1 is that Example 8 adjusted the parameters in step 3) of the container preparation method, specifically: 3) Put the container embryo into the mold cavity, seal the mold cavity after closing the mold, carry out stretching at 130°C, the stretching ratio is 1.2, carry out the first blowing with a low pressure of 4.2 bar, then carry out the second blowing with a pressure of 8.0 bar, and then blow air from the top of the stretching rod with a pressure of 6.5 bar to form, and finally eject and cool at 25°C for 3 hours to set, obtaining the container matrix; among them, the radial stretching and blowing ratio is 2.5, and the axial blowing ratio is 2.4, obtaining the container matrix; for other steps, the parameters are the same as those of Example 1.

[0108] Comparative Example 1

[0109] The difference between Comparative Example 1 and Example 1 lies in that for the container provided in Comparative Example 1, the outer surface of the container matrix is not provided with an aluminum film layer, and the preparation raw materials and dosages of the container matrix are the same as those in Example 1; for the preparation method of the container in Comparative Example 1, step 4) is not carried out, that is, surface plasma treatment and magnetron sputtering coating are not carried out, and other steps are the same as those in Example 1.

[0110] Comparative Example 2

[0111] The difference between Comparative Example 2 and Example 1 lies in that the preparation raw materials of the container matrix in Comparative Example 2 lack low-molecular-weight PLA-PCL, and the lacking amount is supplemented by PLA, that is, the preparation raw materials of the container matrix include: 68 parts of PLA, 4.5 parts of branched PLA, 36 parts of P34HB, 10 parts of soybean oil polyol, 0.8 part of dibutyltin dilaurate, 1 part of flow modifier, and 0.5 part of antioxidant 1010. The preparation method of the container in Comparative Example 2 is the same as that in Example 1.

[0112] Comparative Example 3

[0113] The difference between Comparative Example 3 and Example 1 lies in that the preparation raw materials of the container matrix in Comparative Example 3 lack branched PLA, and the lacking amount is supplemented by PLA, that is, the preparation raw materials of the container matrix include: 52.5 parts of PLA, 20 parts of low-molecular-weight PLA-PCL, 36 parts of P34HB, 10 parts of soybean oil polyol, 0.8 part of dibutyltin dilaurate, 1 part of flow modifier, and 0.5 part of antioxidant 1010. The preparation method of the container in Comparative Example 3 is the same as that in Example 1.

[0114] Performance Test

[0115] Take standard samples of the containers prepared in Examples 1-8 and Comparative Examples 1-3 for relevant mechanical properties, water and oxygen barrier properties, and degradation tests, and the results are shown in Table 1.

[0116] The relevant performance tests are carried out with reference to the following standards:

[0117] GB / T 19789-2005 Packaging materials - Plastics films and sheets - Determination of oxygen transmission rate - Coulometer detection method;

[0118] GB / T 30412-2013 Plastics films and sheets - Determination of water vapor transmission rate - Humidity sensor method;

[0119] GB / T 1040.3-2006 Plastics - Determination of tensile properties - Part 3: Test conditions for films and sheets;

[0120] GB / T 8809-2015 Plastics films - Method for pendulum impact test.

[0121] Table 1

[0122]

[0123] It can be seen from the data in Table 1 that:

[0124] Compared with Example 1, in Comparative Example 1, due to the absence of the aluminum film layer, both the oxygen transmission rate and the water vapor transmission rate are significantly increased, that is, the barrier property is significantly decreased.

[0125] Compared with Example 1, Comparative Example 2 and Comparative Example 3 lack low molecular weight PLA-PCL and branched PLA respectively, and the elongation at break is significantly decreased, that is, the flexibility is significantly decreased; in addition, due to poor compatibility in Comparative Example 2 and Comparative Example 3, uneven phases are likely to be generated during processing, which in turn leads to a significant decrease in the barrier property after coating. At the same time, due to its unevenness, stress concentration is likely to occur during the stretching process, resulting in rupture, which in turn also damages the aluminum film layer on the surface, thus causing the barrier property to be easily greatly reduced during stretching deformation.

[0126] The above has specifically described the preferred embodiments of the present invention, but the present invention is not limited to the described embodiments. Those skilled in the art can also make various equivalent variations or substitutions without departing from the spirit of the present invention, and these equivalent variations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A container, characterized in that, It includes a container substrate and an aluminum film layer. The aluminum film layer is deposited on the outer surface of the container substrate. By mass fraction, the raw materials for preparing the container substrate include: 33 - 52 parts of PLA, 16 - 28 parts of PLA-PCL block copolymer, 3 - 5 parts of branched PLA, 24 - 38 parts of P34HB, 4 - 12 parts of soybean oil polyol, and 0.5 - 1 part of an organotin catalyst; The branched PLA is a 4-arm branched polylactic acid, and its molecular structural formula is as follows: ； Wherein, R represents CH or C2H3, R’ represents an alkyl group, a = 200 - 400, b = 200 - 400, c = 250 - 400, d = 300 - 650; The P34HB is poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and its molecular structural formula is as follows: ； Wherein, n = 200 - 500, m = 60 - 140.

2. The container according to claim 1, characterized in that, The weight-average molecular weight of the PLA-PCL block copolymer is 40,000 - 100,000, and the molar ratio of PLA to PCL therein is (0.5 - 1.5):

1.

3. The container according to claim 1, characterized in that, The weight-average molecular weight of the branched PLA is 82,000 - 164,000.

4. The container according to claim 1, characterized in that, The organotin catalyst is dibutyltin dilaurate and / or stannous octoate.

5. The container according to claim 1, characterized in that, A topcoat layer is provided on the outer surface of the aluminum film layer, and the components of the topcoat layer are polyacrylate and / or polyurethane.

6. The container according to claim 1, characterized in that, The thickness of the aluminum film layer is 10 - 50 μm.

7. A method for preparing the container according to any one of claims 1-6, characterized in that, It includes the following steps: 1) Mix the raw materials for preparing the container substrate, extrude and granulate to obtain pellets; 2) Inject mold the pellets to obtain a container embryo; 3) Blow mold the container embryo to obtain a container substrate; 4) Perform surface plasma treatment on the container substrate, and then perform magnetron sputtering coating to form an aluminum film layer on the outer surface of the container substrate to obtain the container.

8. The preparation method according to claim 7, characterized in that, In step 2), the conditions for the injection molding include: The temperature is 220 - 240 °C, the back pressure is 35 - 65 bar, and the injection time is 4 - 6 s.

9. The preparation method according to claim 7, wherein In step 4), the conditions for the magnetron sputtering coating include: The vacuum degree is 0.8 - 1.1×10 -2 Pa, the target-substrate distance is 55 - 80 mm, the sputtering power is 700 - 900 W, and the sputtering time is 90 - 140 s.

Images