A bio-based material composite hose and preparation method thereof

Abstract

The present invention discloses a bio-based composite hose and a preparation method thereof, belonging to the technical field of aluminum-plastic pipes. The bio-based composite hose provided by the present invention includes a pipe head and a pipe body, wherein the pipe body is formed by overlapping a bio-based composite sheet, and the bio-based composite sheet sequentially includes an outer polylactic acid film, an adhesive layer, an aluminum foil, an adhesive layer, and an inner polylactic acid film; the outer polylactic acid film or the inner polylactic acid film, by weight, includes the following components: 70 to 90 parts of polylactic acid, 5 to 20 parts of polyhydroxybutyrate-co-valerate, and 10 to 30 parts of hyperbranched polycaprolactone terminated with a long carbon chain. The present invention is used in a composite hose by using a modified polylactic acid film with complete biodegradability, and the modified polylactic acid film can be degraded under the action of microorganisms after the end of the use cycle, which is convenient for the recovery of aluminum foil, and its biocompatibility is more conducive to the application in food packaging, biomedical packaging, and cosmetic packaging.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum-plastic pipes, in particular to a bio-based material composite hose and a preparation method thereof. Background Art

[0002] Hose packaging refers to a soft packaging container used to package paste-like or high-viscosity liquid goods. It has the characteristics of light weight, easy to carry, strong and durable, recyclable, easy to squeeze, good processing performance and printing adaptability, etc. At the same time, it is cheap compared to plastic bottle packaging. At present, the composite hose packaging materials used in toothpaste, cosmetics, biomedicine and other products on the market are mainly aluminum-plastic composite or all-plastic composite structures. Aluminum-plastic composite hose is a packaging container made of aluminum foil and plastic film through a co-extrusion composite process, and then processed into a tube by a special tube making machine. Its typical structure is PE / PE+EAA+Al+EAA+PE. In recent years, bio-based materials have attracted attention due to their renewable and degradable properties. Polylactic acid (PLA) is a fully biodegradable thermoplastic polymer with good mechanical properties, transparency and biocompatibility, and is widely used in the biomedical industry. PLA has high tensile strength and compression, but high crystallinity, high brittleness, poor barrier properties, poor hydrophilicity, and poor compatibility with most toughening agents. When it is modified with toughening agents, phase separation is likely to occur, which in turn affects the mechanical properties. In order to improve the performance of PLA and make it suitable for composite hoses, it still needs to be modified. Summary of the invention

[0003] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a bio-based material composite hose and a preparation method thereof, by adding polyhydroxybutyrate-co-valerate and long carbon chain-terminated hyperbranched polycaprolactone into the polylactic acid material for modification, the elongation at break, oxygen barrier properties, water vapor barrier properties and heat resistance of the polylactic acid material are improved, so that the polylactic acid film is suitable for the use requirements of the composite hose.

[0004] The technical solution for achieving the purpose of the present invention is as follows:

[0005] A bio-based composite hose, comprising a pipe head and a pipe body, wherein the pipe body is formed by overlapping bio-based composite sheets, wherein the bio-based composite sheets sequentially comprise an outer polylactic acid film, an adhesive layer, an aluminum foil, an adhesive layer and an inner polylactic acid film;

[0006] The outer layer polylactic acid film or the inner layer polylactic acid film comprises the following components by weight: 70-90 parts of polylactic acid, 5-20 parts of polyhydroxybutyrate-co-valerate, and 10-30 parts of hyperbranched polycaprolactone terminated with a long carbon chain;

[0007] The preparation method of long carbon chain terminated hyperbranched polycaprolactone comprises the following steps:

[0008] (1) a polyol and a dihydroxymethyl carboxylic acid are subjected to an esterification reaction in the presence of a catalyst to obtain a hyperbranched polyester; the polyol molecule contains more than two hydroxyl groups;

[0009] (2) using the hyperbranched polyester as a macromolecular initiator to initiate a ring-opening polymerization reaction of caprolactone under the action of catalyst 2 to obtain a hyperbranched polycaprolactone;

[0010] (3) The saturated fatty acid and the hyperbranched polycaprolactone are further subjected to an esterification reaction in the presence of a catalyst to obtain a hyperbranched polycaprolactone terminated with a long carbon chain.

[0011] Polyhydroxybutyrate-co-valerate (PHBV) is a copolymer composed of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) monomers. This material is synthesized by microbial fermentation and has complete biodegradability, good biocompatibility and processing properties. Melt blending of polylactic acid and PHBV can significantly improve the elongation at break and heat resistance of polylactic acid, and reduce its oxygen permeability and water vapor permeability. However, the compatibility of PHBV and polylactic acid is poor, and generally a compatibilizer needs to be added for blending. Studies have shown that diisocyanate can be used as a compatibilizer to improve the compatibility of polylactic acid and PHBV, but it is highly toxic and difficult to be used in packaging materials for food, biomedicine and cosmetics.

[0012] Caprolactone is naturally present in hot milk and fruit, and can also be produced from 5-hydroxymethylfurfural. It is used as a food additive and has good biocompatibility and biodegradability. Linear polycaprolactone (PCL) has been shown to be able to adjust the degradation rate of polylactic acid and improve its toughness when used for polylactic acid modification, but linear polycaprolactone is not compatible with polylactic acid. The invention uses a hyperbranched polyester with multiple hydroxyl terminal groups as an initiator to synthesize a polycaprolactone with a hyperbranched structure. The polycaprolactone with a hyperbranched structure has better fluidity than a linear polycaprolactone, is conducive to melt blending with polylactic acid, and has more terminal functional groups. Saturated fatty acids containing a long carbon chain structure are reacted with the terminal hydroxyl groups of the hyperbranched polycaprolactone to obtain a long carbon chain-terminated hyperbranched polycaprolactone, which can greatly improve the compatibility of the polycaprolactone with the polylactic acid and has a volume-increasing effect on the blending of PHBV and the polylactic acid, thereby ensuring the balance between the tensile strength and the elongation at break of the polylactic acid material, and further improving the oxygen barrier property, the water vapor barrier property and the heat resistance of the polylactic acid.

[0013] Specifically, in step (1), the polyol is at least one of propylene glycol, trimethylolpropane, pentaerythritol and dipentaerythritol; preferably, the polyol is trimethylolpropane.

[0014] Specifically, the dihydroxymethyl carboxylic acid is at least one of 2,2-dihydroxymethyl propionic acid and 2,2-dihydroxymethyl butyric acid; preferably, the dihydroxymethyl carboxylic acid is 2,2-dihydroxymethyl propionic acid.

[0015] Specifically, the molar ratio of the polyol to dihydroxymethyl carboxylic acid is 1:(45-46), and the amount of the catalyst added is 0.9-3.0 mol% of the dihydroxymethyl carboxylic acid.

[0016] Specifically, in step (2), the mass ratio of the hyperbranched polyester to caprolactone is 1:(10-30), the second catalyst is an organic tin catalyst, preferably, the organic tin catalyst is 2-ethylhexanoate tin; and the temperature of the ring-opening polymerization reaction is 100-140°C.

[0017] Specifically, in step (3), the carbon chain length of the saturated fatty acid molecule is 12 to 22 carbon atoms. Preferably, the saturated fatty acid is selected from at least one of lauric acid, myristic acid, palmitic acid, stearic acid, and arachidic acid; further preferably, the saturated fatty acid is stearic acid.

[0018] Preferably, the amount of the saturated fatty acid added is 24 to 26 times that of the polyol, and the amount of the catalyst 1 added is 0.9 to 3.0 mol% of the saturated fatty acid.

[0019] Specifically, the catalyst in step (1) and step (3) is p-toluenesulfonic acid, and the temperature of the esterification reaction is 120-140°C.

[0020] In a specific embodiment, the thickness of the outer polylactic acid film is 75-100 μm; the thickness of the adhesive is 20-50 μm; the thickness of the aluminum foil is 9-20 μm; and the thickness of the inner polylactic acid film is 65-85 μm.

[0021] Specifically, the polylactic acid materials of the outer polylactic acid film and the inner polylactic acid film can be polylactic acid materials of the same ratio or different ratios. Preferably, the polylactic acid materials of the outer polylactic acid film and the inner polylactic acid film are polylactic acid materials of the same ratio.

[0022] Specifically, the adhesive layer is at least one of ethylene-methacrylic acid copolymer and ethylene-acrylic acid copolymer.

[0023] In a specific embodiment, the outer layer of the bio-based material composite sheet also includes a printed polylactic acid film for printing a trademark pattern. The thickness of the printed polylactic acid film is 20 to 80 μm. The printed polylactic acid film may be transparent or white. The transparent printed polylactic acid film has the same components and weight as the outer layer polylactic acid film. The white polylactic acid film further includes 0 to 5 parts of titanium dioxide on the basis of the outer layer polylactic acid film.

[0024] Specifically, the bio-based material composite sheet is produced by a multi-layer co-extrusion process.

[0025] In a specific embodiment, polylactic acid, polyhydroxybutyrate-co-valerate, and long carbon chain-terminated hyperbranched polycaprolactone are added to an extruder according to a ratio for melt extrusion to form a polylactic acid melt, and the polylactic acid melt, the adhesive layer, the aluminum foil, the adhesive layer, and the polylactic acid melt are put into the extruder corresponding to the five-layer co-extrusion casting machine, and a film is made by a co-extrusion casting process, and then a corona treatment is performed using a corona machine to obtain a bio-based material composite sheet.

[0026] The present invention also protects a method for preparing a bio-based material composite hose, comprising the following steps: overlapping the bio-based material composite sheets into a tube body using a hose reel, induction heating and pressurized cooling the overlapping parts using a high-frequency induction coil, to obtain a bio-based material composite hose.

[0027] Preferably, the overlap size is 2-2.5 mm; the induction heating temperature is 85-95° C., and the compression ratio of the weld after pressurization is 5-20%.

[0028] Another object of the present invention is to protect the application of the above-mentioned bio-based material composite hose in food packaging, biopharmaceutical packaging and cosmetic packaging.

[0029] Beneficial Effects

[0030] The present invention provides a bio-based material composite hose and a preparation method thereof, wherein polyhydroxybutyrate-co-valerate and long carbon chain-terminated hyperbranched polycaprolactone are added to a polylactic acid material for blending and modification, wherein the long carbon chain-terminated hyperbranched polycaprolactone greatly improves the compatibility of polycaprolactone with polylactic acid, and can be used as a volume extender to improve the compatibility of polyhydroxybutyrate-co-valerate with polylactic acid, thereby ensuring the balance between the tensile strength and the elongation at break of the polylactic acid material, and improving the oxygen barrier property, the water vapor barrier property and the heat resistance of the polylactic acid, achieving the water and oxygen barrier effect of the bio-based material composite hose, and effectively ensuring the activity and safety of the contents of the bio-based material aluminum-plastic composite hose.

[0031] The present invention uses a modified polylactic acid material with complete biodegradability to replace polyethylene, a traditional petroleum-based material, in the preparation of a composite hose. The modified polylactic acid material can be degraded by microorganisms after the use cycle, which is convenient for the recycling of aluminum foil. Its biocompatibility is conducive to its application in food packaging, biomedical packaging and cosmetic packaging, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1Infrared spectra of hyperbranched polyester, hyperbranched polycaprolactone and hyperbranched polycaprolactone terminated with long carbon chains. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0035] The raw materials used in the embodiments and comparative examples are described as follows:

[0036] Aluminum foil: thickness 12 μm, purchased from Xiashun Aluminum Foil Co., Ltd.

[0037] Ethylene-methacrylic acid copolymer: Surlyn EMAA 7940, DuPont;

[0038] Polylactic acid: REVODE190, purchased from Zhejiang Hisun Biomaterials Co., Ltd.;

[0039] Polyhydroxybutyrate-co-valerate: ENMAT Y1000P, purchased from Ningbo Tianan Biomaterial Co., Ltd.; hydroxyvalerate content: 3 mol%;

[0040] Polycaprolactone: PLACCEL 305, Daicel from Japan;

[0041] Caprolactone: 6-caprolactone, purity 99%, purchased from Shenzhen Xingkaiyue Biotechnology Co., Ltd.;

[0042] Polyol 1: trimethylolpropane, purity: 98%, purchased from Guangzhou Hewei Pharmaceutical Technology Co., Ltd.;

[0043] Polyol 2: pentaerythritol, purity: 98%, purchased from Hubei Yihua Chemical Co., Ltd.;

[0044] Polyol 3: propylene glycol, purity 99%, purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd.;

[0045] Dihydroxymethyl carboxylic acid: 2,2-dihydroxymethyl propionic acid, purity: 98%, purchased from Guangzhou Hewei Pharmaceutical Technology Co., Ltd.;

[0046] p-Toluenesulfonic acid: Product number: PA05704, purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.;

[0047] Tin 2-ethylhexanoate: Product number: WB04727, purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.;

[0048] Saturated fatty acid 1: stearic acid, purchased from Zhongfu Oils and Fats Group Co., Ltd.;

[0049] Saturated fatty acid 2: palmitic acid, purchased from Zhongfu Oils and Fats Group Co., Ltd.;

[0050] Saturated fatty acid 3: lauric acid, purchased from Zhongfu Oils and Fats Group Co., Ltd.;

[0051] Long carbon chain terminated hyperbranched polycaprolactone 1: Homemade, the preparation method is as follows:

[0052] (1) In a nitrogen atmosphere, 1 mol of polyol 1, 45.2 mol of dihydroxymethyl carboxylic acid and 1.3 mol of p-toluenesulfonic acid are mixed, and stirred for reaction at 140° C. for 10 hours to obtain a hyperbranched polyester. A drying tube filled with anhydrous magnesium sulfate is provided in the reaction system to remove water generated in the reaction. After the reaction is completed, the p-toluenesulfonic acid in the system is removed by washing with deionized water, and then purified by silica gel column chromatography (the eluent is petroleum ether:ethyl acetate in a volume ratio of 9:1). The structural formula of the hyperbranched polyester is as follows:

[0053] ;

[0054] (2) 1 part by weight of the hyperbranched polyester is melted in a reactor, and then dried at 100° C. under vacuum for 6 hours, and then 0.4 parts by weight of tin 2-ethylhexanoate is added dropwise to the reactor, and stirred evenly at 140° C., and 20 parts by weight of caprolactone is added, and stirring is continued for 24 hours to generate hyperbranched polycaprolactone, and cold formaldehyde is added to precipitate the product, and after filtering, the product is washed with petroleum ether for 3 times to remove the tin 2-ethylhexanoate, and then washed with anhydrous ethanol for 3 times to remove the petroleum ether, and dried at 40° C. to obtain hyperbranched polycaprolactone;

[0055] (3) In a nitrogen atmosphere, the hyperbranched polycaprolactone obtained in step (2) is melted in a reactor, 25 mol parts of saturated fatty acid 1 and 0.75 mol parts of p-toluenesulfonic acid are added, and the mixture is stirred and reacted at 140° C. for 3 hours. Similarly, a drying tube containing anhydrous magnesium sulfate is set in the reaction system to remove water generated in the reaction. After the reaction is completed, the p-toluenesulfonic acid in the system is washed with deionized water to remove the p-toluenesulfonic acid, and the mixture is dried to obtain a hyperbranched polycaprolactone with a long carbon chain end cap.

[0056] The hyperbranched polyester, hyperbranched polycaprolactone, and long carbon chain terminated hyperbranched polycaprolactone obtained in steps (1) to (3) were subjected to infrared spectroscopy analysis. The sample was mixed with potassium bromide at a weight ratio of 1:100 to prepare a pressed tablet for Fourier transform infrared measurement. The Fourier transform infrared spectrometer was Nicolet 8700, manufactured by Thermo Fisher Scientific. The obtained spectrum was as shown in FIG. Figure 1 As shown. Among them, 3500cm -1 The absorption peak of hydroxyl is 1730cm -1 The stretching vibration absorption peak of C=O is 1468cm -1 is the bending vibration absorption peak of -CH2-, 730cm -1 -(CH2) n -, n>4 characteristic absorption peak. From the infrared spectrum, it can be seen that hyperbranched polycaprolactone has a higher absorption peak at 730 cm-1 than hyperbranched polyester. -1 -(CH2) appears n -, n>4 characteristic absorption peaks, proving the successful ring-opening polymerization of polycaprolactone. Compared with hyperbranched polycaprolactone, the hyperbranched polycaprolactone terminated with long carbon chains has a higher absorption peak at 730 cm -1 The absorption peak at 3500 cm -1 The hydroxyl absorption peak at almost disappeared, proving that the esterification reaction between saturated fatty acids and the hydroxyl end groups of hyperbranched polycaprolactone successfully produced long carbon chain terminated hyperbranched polycaprolactone.

[0057] Hyperbranched polycaprolactone with long carbon chain end-capping 2: homemade, the preparation method is different from that of hyperbranched polycaprolactone with long carbon chain end-capping 1, except that the polyol 1 in step (1) is replaced by polyol 2;

[0058] Hyperbranched polycaprolactone with long carbon chain end-capping 3: homemade, the preparation method is different from that of hyperbranched polycaprolactone with long carbon chain end-capping 1, except that the polyol 1 in step (1) is replaced by polyol 3;

[0059] Hyperbranched polycaprolactone with long carbon chain end-capping 4: homemade, the preparation method is different from that of hyperbranched polycaprolactone with long carbon chain end-capping 1, except that the saturated fatty acid 1 in step (3) is replaced by a saturated fatty acid 2;

[0060] Hyperbranched polycaprolactone with long carbon chain end-capping 5: homemade, the preparation method is different from that of hyperbranched polycaprolactone with long carbon chain end-capping 1, except that the saturated fatty acid 1 in step (3) is replaced by saturated fatty acid 3;

[0061] Hyperbranched polycaprolactone terminated with hydroxyl groups: homemade, the preparation method is different from the hyperbranched polycaprolactone 1 terminated with long carbon chains, except that step (3) is not performed;

[0062] Long carbon chain terminated linear polycaprolactone: homemade, preparation method: in a nitrogen atmosphere, 1 weight part of commercially available polycaprolactone was melted in a reactor, 25 weight parts of saturated fatty acid 1 and 0.75 weight parts of p-toluenesulfonic acid were added, and the mixture was stirred and reacted at 140°C for 3 hours. A drying tube containing anhydrous magnesium sulfate was also set in the reaction system to remove water generated in the reaction. After the reaction was completed, the p-toluenesulfonic acid in the system was washed with deionized water to obtain a linear polycaprolactone with a long carbon chain terminated;

[0063] Unless otherwise specified, the components and raw materials used in the embodiments and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0064] Examples and Comparative Examples

[0065] As shown in Table 1, polylactic acid, polyhydroxybutyrate-co-valerate, and long carbon chain-terminated hyperbranched polycaprolactone are added to an extruder according to a ratio and melt-extruded to form a polylactic acid melt;

[0066] Put polylactic acid melt, ethylene-methacrylic acid copolymer, aluminum foil, ethylene-methacrylic acid copolymer and polylactic acid melt into the extruder corresponding to the five-layer co-extrusion casting machine, and make a film through the co-extrusion casting process, and then use a corona machine to perform corona treatment to obtain a bio-based material composite sheet, wherein the thickness of the outer polylactic acid film is 80 μm, the thickness of the ethylene-methacrylic acid copolymer is 20 μm, the thickness of the aluminum foil is 9 μm, the thickness of the ethylene-methacrylic acid copolymer is 20 μm, and the thickness of the inner polylactic acid film is 80 μm.

[0067] The bio-based material composite sheet is overlapped and formed into a tube body by a hose reel, and the overlap is induction heated and pressurized cooled by a high-frequency induction coil to obtain an aluminum-plastic composite hose, wherein the overlap size is 2.5 mm; the induction heating temperature is 95° C., and the weld compression ratio after pressurization is 5%. The weld compression ratio is calculated as follows: weld compression ratio = (thickness of the overlap before welding - thickness of the joint after welding) / thickness of the overlap before welding × 100%.

[0068] Table 1 Components and ratios of bio-based composite sheet polylactic acid film

[0069]

[0070] The prepared polylactic acid film, bio-based composite sheet and aluminum-plastic composite hose were subjected to the following performance tests, and the results are shown in Table 2:

[0071] (1) Tensile strength and elongation at break: The tensile strength and elongation at break of the polylactic acid film were tested in accordance with the provisions of GB / T 1040.3-2006, using a long specimen with a length of >150 mm and a width of 15 mm. The distance between the specimen fixtures was (100±5) mm, and the specimen tensile speed (no load) was (200±20) mm / min.

[0072] (2) Interlayer peel strength: The interlayer peel strength between bio-based material sheets is tested according to the method of the national light industry standard "Aluminum-plastic composite hose for toothpaste (QB / T 2901-2012)" (unit: N / 15mm). The specific requirements are as follows: 1) Instrument used: universal tensile testing machine; 2) Take 3 to 5 material samples with a width of 15mm, a length of about 150mm, and flat edges for testing, and take the average value; 3) Peel off the layered sheets at a speed of 100mm / min. The force tested by the instrument is the required force. Since the outer layer of polylactic acid and the adhesive layer are the same as the inner layer of polylactic acid and the adhesive layer, the peel strength between the outer layer of polylactic acid and the inner layer of polylactic acid and the aluminum foil is not distinguished here, but the average value of the three peel strengths is taken;

[0073] (3) Water vapor barrier performance: The water vapor permeability of the polylactic acid film was tested using a 3-33MA moisture permeator in accordance with GB / T 1037-1988. The specific test conditions were as follows: test temperature: 25°C, test pressure: 1 atm, ambient humidity: 90% RH, gas atmosphere: water vapor, test time: 24 hours;

[0074] (4) Oxygen barrier performance: refer to GB / T 19789-2021 standard to test the oxygen permeability of polylactic acid film. The specific test conditions are as follows: test temperature room temperature: 25°C, test pressure: 1atm, ambient humidity: 50%RH, test time: 24 hours; place the sample in a dryer filled with anhydrous calcium chloride or other desiccant for sample state adjustment for no less than 48 hours;

[0075] (5) Heat resistance: Referring to GB / T 29336-2012 standard, water was injected into the bio-based composite hose to fill two-thirds of the capacity. After being placed in an environment of (48±2)℃ for 48 hours, the hose was observed for cracks. The crack length was divided into the following grades: 0cm-no crack, 0~1cm-slight crack, 1~3cm-moderate crack, and greater than 3cm-severe crack.

[0076] Table 2 Performance test results of polylactic acid film, bio-based material sheet, and bio-based material composite hose

[0077]

[0078] From the performance test results of the embodiments and comparative examples, it can be seen that the elongation at break of polylactic acid modified with polyhydroxybutyrate-co-valerate and long carbon chain terminated hyperbranched polycaprolactone is greatly improved, and the tensile strength is still maintained in the range of ≥30MPa, thereby ensuring the mechanical properties of the polylactic acid film. Among them, polyhydroxybutyrate-co-valerate has good barrier properties. Under the action of long carbon chain terminated hyperbranched polycaprolactone, the oxygen barrier property, water vapor barrier property and heat resistance of the polylactic acid material are improved. After being compounded with aluminum foil, it can meet the performance requirements of the composite hose, and has good biocompatibility and is biodegradable, which is beneficial to the recycling of aluminum foil.

[0079] It can be seen from Examples 3 to 5 that the selection of polyols has no significant effect on the performance of the polylactic acid film material; it can be seen from Examples 3, 6, and 7 that when the saturated fatty acid with a longer carbon chain length is used as the end-capping group, the long carbon chain-terminated hyperbranched polycaprolactone has a more obvious volume-enhancing and modification effect on polylactic acid.

[0080] It can be seen from Comparative Example 1 that although hyperbranched polycaprolactone without long carbon chain as end group can also improve the elongation at break of polylactic acid, the tensile strength is greatly reduced, and the volume-increasing effect on polyhydroxybutyrate-co-valerate is also poor, thereby affecting the barrier properties and heat resistance of polylactic acid.

[0081] It can be seen from Comparative Examples 2 and 3 that the modification effects of polycaprolactone and long carbon chain modified polycaprolactone on polylactic acid and polyhydroxybutyrate-co-valerate are not obvious. This is because there are too few terminal hydroxyl sites in linear polycaprolactone and the modification effect of long carbon chain is limited.

[0082] It can be seen from Comparative Examples 4 and 5 that polycaprolactone itself does not contribute to the barrier properties of polylactic acid, but instead leads to a decrease in gas barrier properties and water vapor barrier properties.

[0083] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A bio-based composite hose, characterized in that: It comprises a pipe head and a pipe body, wherein the pipe body is formed by overlapping bio-based material composite sheets, and the bio-based material composite sheets sequentially comprise an outer layer of polylactic acid film, an adhesive layer, an aluminum foil, an adhesive layer and an inner layer of polylactic acid film; The outer layer polylactic acid film or the inner layer polylactic acid film comprises the following components by weight: 70-90 parts of polylactic acid, 5-20 parts of polyhydroxybutyrate-co-valerate, and 10-30 parts of hyperbranched polycaprolactone terminated with a long carbon chain; The preparation method of long carbon chain terminated hyperbranched polycaprolactone comprises the following steps: (1) In a nitrogen atmosphere, a polyol with a molar ratio of 1:(45-46) and a dihydroxymethyl carboxylic acid are subjected to an esterification reaction at 120-140° C. under the action of p-toluenesulfonic acid to prepare a hyperbranched polyester; the polyol is at least one of propylene glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol; and the dihydroxymethyl carboxylic acid is at least one of 2,2-dihydroxymethyl propionic acid and 2,2-dihydroxymethyl butyric acid; (2) Using hyperbranched polyester as a macromolecular initiator, in the presence of an organic tin catalyst, caprolactone undergoes a ring-opening polymerization reaction at 100-140°C to obtain hyperbranched polycaprolactone, wherein the mass ratio of the hyperbranched polyester to caprolactone is 1:(10-30); (3) In a nitrogen atmosphere, saturated fatty acids and hyperbranched polycaprolactone are further subjected to esterification reaction at 120-140°C in the presence of p-toluenesulfonic acid to obtain long carbon chain-terminated hyperbranched polycaprolactone. The carbon chain length of the saturated fatty acid molecule is 12-22 carbon atoms, and the amount of saturated fatty acid added is 24-26 times that of the polyol.

2. The bio-based composite hose according to claim 1, characterized in that: In step (1), the amount of p-toluenesulfonic acid added is 0.9-3.0 mol % of dihydroxymethylcarboxylic acid.

3. The bio-based composite hose according to claim 1, characterized in that: In step (3), the amount of p-toluenesulfonic acid added is 0.9-3.0 mol% of the saturated fatty acid.

4. The bio-based composite hose according to claim 1, characterized in that: The thickness of the outer polylactic acid film is 75-100 μm; the thickness of the adhesive layer is 20-50 μm; the thickness of the aluminum foil is 9-20 μm; and the thickness of the inner polylactic acid film is 65-85 μm.

5. The bio-based composite hose according to claim 1, characterized in that: The adhesive layer is at least one of ethylene-methacrylic acid copolymer and ethylene-acrylic acid copolymer.

6. The bio-based composite hose according to claim 1, characterized in that: The bio-based material composite sheet is prepared by a multi-layer co-extrusion process.

7. The method for preparing a bio-based material composite hose according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: overlapping the bio-based material composite sheet by a hose reel to form a pipe body; and induction heating and pressurized cooling are performed on the overlapping part by a high-frequency induction coil to obtain a bio-based material composite hose.

8. Use of the bio-based composite hose according to any one of claims 1 to 6 in food packaging, biopharmaceutical packaging and cosmetic packaging.

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