Modified polylactic acid fiber material and its preparation method and application, packaging material

Abstract

The present application relates to a modified polylactic acid fiber material and its preparation method and application, and packaging material. The preparation method of the modified polylactic acid fiber material comprises the following steps: modifying polylactic acid with a toughening agent to obtain a modified polylactic acid masterbatch; spinning the modified polylactic acid masterbatch to obtain a modified polylactic acid fiber material; wherein the toughening agent is selected from at least one of ethylene-butyl acrylate-glycidyl methacrylate copolymer, polybutylene adipate / terephthalate and ethylene-1-octene copolymer. By modifying polylactic acid with a specific type of toughening agent, the toughness of polylactic acid can be effectively improved; when the obtained modified polylactic acid fiber material is used to prepare packaging materials, the packaging materials can be given higher folding resistance and mechanical properties.

Description

Technical Field

[0001] The present application relates to the field of material technology, and in particular to a modified polylactic acid fiber material, a preparation method and application thereof, and a packaging material. Background Art

[0002] Packaging materials include paper, metal, plastic and wood, among which paper has the advantages of wide material sources, low production cost, simple production process and green environmental protection, and is widely used in packaging materials. At present, paper prepared by traditional methods can meet most daily use requirements, but in areas where toughness is required, secondary processing methods such as paper-plastic composite are usually used to give paper the required properties. However, after secondary processing, the toughness of paper is improved, but at the same time, it also increases problems such as difficulty in recycling and difficulty in degradation.

[0003] Therefore, it is of great significance to provide a packaging material that is highly tough and biodegradable. Summary of the invention

[0004] Based on this, the present application provides a highly tough and degradable modified polylactic acid fiber material, its preparation method and application, and packaging material.

[0005] The technical solution of this application to solve the above technical problems is as follows.

[0006] A method for preparing a modified polylactic acid fiber material comprises the following steps:

[0007] The polylactic acid is modified by a toughening agent to obtain a modified polylactic acid masterbatch; the toughening agent is at least one selected from ethylene-butyl acrylate-glycidyl methacrylate copolymer, polybutylene adipate / terephthalate and ethylene-1-octene copolymer;

[0008] The modified polylactic acid masterbatch is spun to obtain a modified polylactic acid fiber material.

[0009] In some of the embodiments, in the method for preparing the modified polylactic acid fiber material, the mass ratio of the toughening agent to the polylactic acid is (0.05-0.15):1.

[0010] In some embodiments, in the method for preparing the modified polylactic acid fiber material, the modification comprises the following steps:

[0011] After the polylactic acid and the toughening agent are mixed, melt extrusion and granulation are carried out in sequence.

[0012] In some of the embodiments, in the method for preparing the modified polylactic acid fiber material, the solvent in the spinning is selected from at least one of chloroform and acetone.

[0013] A modified polylactic acid fiber material is prepared by adopting the preparation method of the modified polylactic acid fiber material.

[0014] The present application provides the use of the modified polylactic acid fiber material in the preparation of polylactic acid fiber products.

[0015] The present application provides a polylactic acid packaging material, comprising the above-mentioned modified polylactic acid fiber material and wood fiber.

[0016] In some of the embodiments, in the polylactic acid packaging material, the mass ratio of the modified polylactic acid fiber material to the wood fiber is (0.05-0.3):1.

[0017] In some embodiments, in the polylactic acid packaging material, the lengths of the modified polylactic acid fiber material and the wood fiber are independently 1 mm to 10 mm.

[0018] The present application provides a method for preparing a polylactic acid packaging material, comprising the following steps:

[0019] The modified polylactic acid fiber material and wood fiber are mixed to make paper.

[0020] Compared with the prior art, the preparation method of the modified polylactic acid fiber material of the present application has the following beneficial effects:

[0021] The preparation method of the above-mentioned modified polylactic acid fiber material modifies polylactic acid by using a specific type of toughening agent. Since the Poisson's ratio of the specific type of toughening agent is different from that of polylactic acid, a large number of small silver streaks can be induced when the material is impacted; compared with pure polylactic acid forming a small number of large silver streaks when impacted, it requires more energy to expand a large number of small silver streaks than to expand a small number of large silver streaks, and more energy is also required when the small silver streaks break, and the number of small silver streaks is far greater than that of large silver streaks, thereby effectively improving the toughness of polylactic acid, that is, the folding resistance is higher; the modified polylactic acid masterbatch is further spun to obtain a modified polylactic acid fiber material, which, when used to prepare packaging materials, can give the packaging materials higher folding resistance and mechanical properties. DETAILED DESCRIPTION

[0022] The technical solution of the present application is further described in detail below in conjunction with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0024] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of the present application, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0025] The weight of the relevant components mentioned in the specification of the examples of this application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the specification of the examples of this application, it is within the scope disclosed in the specification of the examples of this application. Specifically, the weight described in the specification of the examples of this application can be mass units known in the chemical industry such as μg, mg, g, and kg.

[0026] Polylactic acid (PLA) is produced by direct polymerization or ring-opening polymerization with lactic acid as the main raw material. The raw materials come from renewable plant resources. It is non-toxic, non-irritating, biosafe and completely biodegradable. It is an environmentally friendly polymer. In addition, polylactic acid has good mechanical properties and hydrophobic properties. However, polylactic acid is relatively brittle and its folding resistance is insufficient.

[0027] An embodiment of the present application provides a method for preparing a modified polylactic acid fiber material, comprising steps S10 to S20:

[0028] Step S10: modifying the polylactic acid with a toughening agent to obtain a modified polylactic acid masterbatch; wherein the toughening agent is selected from at least one of ethylene-butyl acrylate-glycidyl methacrylate copolymer, polybutylene adipate / terephthalate and ethylene-1-octene copolymer.

[0029] By modifying polylactic acid with a specific type of toughening agent, the toughness of polylactic acid can be effectively improved, and the hydrophobic properties of polylactic acid will not be affected. The inferred working principle is: this specific type of toughening agent conforms to the theory of multiple silver textures in the toughening mechanism of elastomers. Due to the different Poisson's ratios of the plastic and elastomer phases, the stress field of the material is uneven when it is impacted, and stress concentration occurs at the elastomer particles, causing small silver streaks between the elastomer particles; when the elastomer particles are dense, the stress field interacts to make the silver streaks larger, but the elastomer particles will also control the expansion of the silver streaks and terminate the silver streaks without developing into destructive cracks; compared with the large number of silver streaks formed in pure polymers, the addition of rubber elastomers can induce a large number of small silver streaks, and the expansion of a large number of small silver streaks requires more energy than the expansion of a small number of large silver streaks, and more energy is required when the small silver streaks break, and the number of small silver streaks is far greater than that of large silver streaks, thereby effectively improving the toughness of polylactic acid.

[0030] In some of the examples, in step S10, the mass ratio of the toughening agent to the polylactic acid is (0.05-0.15):1.

[0031] It can be understood that the mass ratio of the toughening agent to the polylactic acid includes but is not limited to 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, and 0.15:1.

[0032] In some of these examples, step S10 includes step S11:

[0033] After the polylactic acid and the toughening agent are mixed, melt extrusion and granulation are carried out in sequence.

[0034] In some of the examples, in step S11, a mixer is used to mix the polylactic acid and the toughening agent.

[0035] Optionally, the polylactic acid and the toughening agent are mixed using a SHR-25A high-speed mixer.

[0036] In some of the examples, in step S11, the rotation speed of the mixer is 150 r / min to 500 r / min, and the mixing time is 2 min to 10 min.

[0037] It will be appreciated that the speed of the mixer includes but is not limited to 150r / min, 200r / min, 250r / min, 300r / min, 350r / min, 400r / min, 450r / min, 500r / min, and the mixing time includes but is not limited to 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min.

[0038] In some of the examples, in step S11, the rotation speed of the mixer is 250 r / min, and the mixing time is 3 min.

[0039] In some of the examples, in step S11, a twin-screw extruder is used for melt extrusion.

[0040] Optionally, an AK36 twin-screw extruder is used for melt extrusion.

[0041] In some of the examples, in step S11, the screw speed of the twin-screw extruder is 150 r / min to 250 r / min.

[0042] It will be appreciated that the screw speed of the twin-screw extruder includes but is not limited to 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min, 200 r / min, 210 r / min, 220 r / min, 230 r / min, 240 r / min, and 250 r / min.

[0043] In some of the examples, in step S11, the temperature of the twin-screw extruder is 165°C to 190°C.

[0044] It is understood that the temperature of the twin-screw extruder includes but is not limited to 165° C., 168° C., 170° C., 172° C., 175° C., 178° C., 180° C., 185° C., 188° C., 190° C. It is also understood that the temperature of different zones in the twin-screw extruder can be the same or different.

[0045] In some specific examples, in step S11, the temperatures of zones 1 to 10 of the twin-screw extruder are 165°C, 180°C, 185°C, 185°C, 190°C, 190°C, 190°C, 185°C, and 185°C, respectively.

[0046] In some of the examples, in step S11, the current of the twin-screw extruder is 24A to 26A.

[0047] It can be understood that the current of the twin-screw extruder includes but is not limited to 24A, 25A, and 26A.

[0048] In some of the examples, in step S11, the feeding frequency of the twin-screw extruder is 3 Hz to 10 Hz.

[0049] It will be appreciated that the feeding frequency of the twin-screw extruder includes, but is not limited to, 3 Hz, 4 Hz, 5 Hz, 6 Hz, 7 Hz, 8 Hz, 9 Hz, and 10 Hz.

[0050] In some of the examples, in step S11, the melt pressure of the twin-screw extruder is 1 MPa to 1.5 MPa.

[0051] It can be understood that the melt pressure of the twin-screw extruder includes but is not limited to 1 MPa, 1.1 MPa, 1.25 MPa, 1.3 MPa, 1.4 MPa, and 1.5 MPa.

[0052] In some of the examples, in step S11, a pelletizer is used for pelletizing.

[0053] In some of the examples, in step S11, before the step of mixing the polylactic acid and the toughening agent, the step of drying the polylactic acid and the toughening agent is also included.

[0054] Optionally, place in an electric heated air drying oven for drying.

[0055] In some of the examples, in step S11, the drying temperature is 40°C to 80°C, and the drying time is 6h to 8h.

[0056] It will be appreciated that the drying temperature includes but is not limited to 40°C, 50°C, 60°C, 70°C, and 80°C, and the drying time includes but is not limited to 6h, 6.2h, 6.5h, 6.8h, 7h, 7.2h, 7.4h, 7.5h, 7.6h, 7.8h, and 8h.

[0057] Step S20: Spinning the modified polylactic acid masterbatch to obtain a modified polylactic acid fiber material.

[0058] If the modified polylactic acid masterbatch is not spun, a polylactic acid film will be formed during the papermaking process, making it impossible to mix fibers for papermaking.

[0059] In some examples, step S20 includes steps S21-S22:

[0060] Step S21: Mixing the modified polylactic acid masterbatch with a solvent to obtain a spinning solution.

[0061] In some of the examples, in step S21, the solvent is selected from at least one of chloroform and acetone.

[0062] In some of the examples, in step S21, the solvent is a mixture of chloroform and acetone.

[0063] In some of the examples, in step S21, the mass ratio of chloroform to acetone is (0.5-5):1.

[0064] It will be appreciated that the mass ratio of chloroform to acetone includes, but is not limited to, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, and 5:1.

[0065] In some examples, in step S21 , the concentration of the spinning solution is 1% to 10%.

[0066] It can be understood that the concentration of the spinning solution is the solid content of the spinning solution; it can be further understood that the concentration of the spinning solution includes but is not limited to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%.

[0067] Step S22: Spinning the spinning solution obtained in step S21 to obtain a modified polylactic acid fiber material.

[0068] In some of the examples, in step S22, an electrospinning machine is used to spin the spinning solution.

[0069] In some examples, step S22 includes the following steps:

[0070] The spinning solution is poured into the spinning tube of the electrospinning machine and collected using a roller to obtain a modified polylactic acid fiber material.

[0071] In some examples, in step S22, the diameter of the spinning tube needle of the electrospinning machine is 0.5 mm to 1.0 mm. Optionally, the diameter of the spinning tube needle of the electrospinning machine is 0.9 mm.

[0072] In some examples, in step S22, the spinning voltage is 20 kV to 40 kV, and the pole distance is 10 cm to 20 cm. Optionally, the spinning voltage is 25 kV, and the pole distance is 15 cm.

[0073] In some examples, in step S22, the rotation speed of the roller is 1000 r / min to 2500 r / min. Optionally, the rotation speed of the roller is 2000 r / min.

[0074] In some specific examples, in step S22, the diameter of the spinning tube needle of the electrospinning machine is 0.9 mm, the spinning voltage is 25 kV, the pole distance is 15 cm, the flow rate is 0.1 mL / h, and the roller speed is 2000 r / min.

[0075] One embodiment of the present application provides a modified polylactic acid fiber material, which is prepared using the above-mentioned method for preparing the modified polylactic acid fiber material.

[0076] The modified polylactic acid fiber material prepared by the preparation method of the modified polylactic acid fiber material has high folding resistance and tensile strength.

[0077] One embodiment of the present application provides the use of the modified polylactic acid fiber material in the preparation of polylactic acid fiber products. Another embodiment of the present application provides a polylactic acid fiber product, comprising the modified polylactic acid fiber material.

[0078] It can be understood that polylactic acid fiber products include but are not limited to packaging materials.

[0079] One embodiment of the present application provides a polylactic acid packaging material, including the above-mentioned modified polylactic acid fiber material.

[0080] The modified polylactic acid fiber material is used to prepare polylactic acid packaging materials, which can give the polylactic acid packaging materials higher folding resistance, tensile strength and tightness, and have good hydrophobic properties and are degradable.

[0081] In some of the examples, the polylactic acid packaging material includes the above-mentioned modified polylactic acid fiber material and wood fiber.

[0082] It is understandable that the modified polylactic acid fiber material can be used to directly prepare the polylactic acid packaging material, and wood fiber or other materials can be added on the basis of adding the modified polylactic acid fiber material.

[0083] In some of the examples, in the polylactic acid packaging material, the mass ratio of modified polylactic acid fiber material to wood fiber is (0.05-0.3):1.

[0084] It can be understood that the mass ratio of the modified polylactic acid fiber material to the wood fiber includes but is not limited to 0.05:1, 0.06:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, and 0.3:1.

[0085] In some of the examples, in the polylactic acid packaging material, the lengths of the modified polylactic acid fiber material and the wood fiber are independently 1 mm to 10 mm.

[0086] It can be understood that the lengths of the modified polylactic acid fiber material and the wood fiber can be the same or different; it can be further understood that the lengths of the modified polylactic acid fiber material and the wood fiber are independently 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, and 10mm, respectively.

[0087] In some of the examples, in the polylactic acid packaging material, the wood fiber is selected from at least one of softwood fiber and poplar fiber.

[0088] In some of the examples, in the polylactic acid packaging material, the width of the wood fibers is 40 μm to 60 μm.

[0089] It is understood that the width of the wood fiber includes, but is not limited to, 40 μm, 42 μm, 44 μm, 45 μm, 46 μm, 50 μm, 52 μm, 55 μm, and 60 μm.

[0090] An embodiment of the present application provides a method for preparing a polylactic acid packaging material, comprising step S100.

[0091] Step S100: Mixing the modified polylactic acid fiber material obtained in step S20 with wood fiber to make paper.

[0092] When the modified polylactic acid fiber material obtained in step S20 is used to prepare packaging materials, the packaging materials can be given higher folding resistance, tightness and mechanical properties, and water resistance, while ensuring that the basic properties of the paper are not affected, effectively solving the comprehensive problems of cost, folding resistance, strength and environmental protection of traditional packaging paper; the final tensile strength of the obtained paper can be as high as 46.13MPa, and the tightness can be as high as 0.76g / cm 3 , in line with national standards for paper use; folding endurance can be as high as 3.42 / l gn.

[0093] In some examples, step S100 includes steps S110 to S120:

[0094] Step S110: Mix the modified polylactic acid fiber material obtained in step S20 with wood fiber, and screen and copy to obtain a wet paper blank.

[0095] In some of the examples, in step S110 , the mesh size used for screening is 40-90 mesh.

[0096] Optionally, the mesh size is 60 mesh.

[0097] Step S120: papermaking the wet paper blank obtained in step S110.

[0098] In some examples, step S120 includes the following steps:

[0099] The wet paper blank obtained in step S110 is subjected to pulping, sheeting, wet pressing and hot pressing in sequence.

[0100] In some of the examples, in step S120, the mass fraction of the slurry obtained by the slurrying step is 0.1% to 1%.

[0101] Optionally, the mass fraction of the slurry is 0.2%.

[0102] In some of the examples, in step S120, the temperature of the hot pressing is 168°C to 173°C.

[0103] It is understood that the temperature of hot pressing includes but is not limited to 168°C, 169°C, 170°C, 171°C, 172°C, and 173°C.

[0104] In some of the examples, in step S120 , the pressure of the hot pressing is 4 MPa to 10 MPa, and the time of the hot pressing is 1 min to 5 min.

[0105] It can be understood that the hot pressing pressure includes but is not limited to 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, and 10MPa; the hot pressing time includes but is not limited to 1min, 2min, 3min, 4min, and 5min.

[0106] In some of the examples, in step S120, the hot pressing pressure is 6 MPa, and the hot pressing time is 3 minutes.

[0107] The polylactic acid packaging material and the polylactic acid packaging material prepared by the preparation method of the polylactic acid packaging material have high strength due to the hydrogen bonding force between wood fibers; moreover, the modified polylactic acid fiber material will have a certain fluidity after melting during the hot pressing process, and the melted modified polylactic acid fiber material will penetrate into the porous structure of the wood fibers and bond them together, thereby further improving the strength of the polylactic acid packaging material. At the same time, the modified polylactic acid fiber material has good hydrophobicity, which can effectively improve the water resistance of the polylactic acid packaging material. Specific embodiments

[0109] The following examples are given according to the modified polylactic acid fiber material, preparation method and application thereof, and packaging material of the present application. It can be understood that the modified polylactic acid fiber material, preparation method and application thereof, and packaging material of the present application are not limited to the following embodiments.

[0110] Example 1

[0111] (1) 10 parts of PLA and 1 part of toughening agent polybutylene adipate / terephthalate were placed in an electric hot air drying oven and dried at 60° C. for 7 h, and then the dried materials were placed in a SHR-25A high-speed mixer and mixed at 250 r / min for 3 min; the materials were melt-extruded through an AK36 twin-screw extruder, wherein the temperatures of zones 1 to 10 of the extruder were 165° C., 168° C., 170° C., 172° C., 175° C., 178° C., 180° C., 185° C., 188° C., and 190° C., respectively, the screw speed was 190 r / min, the mainstream motor was 25 A, the feeding frequency was 6 Hz, and the melt pressure was 1 MPa; the extruded modified PLA was pelletized by a pelletizer to obtain a modified PLA masterbatch.

[0112] (2) Chloroform and acetone are mixed in a mass ratio of 2:1 to prepare a spinning solution, and the modified PLA masterbatch obtained in step (1) is dissolved in the spinning solution to prepare a spinning solution with a concentration of 5%; the obtained spinning solution is poured into the spinning tube of an electrospinning machine, and collected by a roller; wherein the spinning tube needle diameter of the electrospinning machine is 0.9 mm, the spinning voltage is 25 kV, the pole distance is 15 cm, the flow rate is 0.1 mL / h, and the collection roller speed is 2000 r / min, thereby obtaining modified PLA fibers.

[0113] (3) The length of the modified PLA fiber obtained in step (2) is about 3 mm, and the length of the wood fiber is about 3 mm. 5 parts of the modified PLA fiber and 95 parts of the wood fiber are mixed evenly by a hydraulic pulping method, and then passed through a 60-mesh standard sieve to form a wet paper blank, and then subjected to pulping, sheeting, wet pressing, and hot pressing, wherein the pulp mass fraction is 0.2%, the hot pressing temperature is 168° C. to 173° C., the hot pressing pressure is 6 MPa, and the hot pressing time is 3 min, to obtain a modified polylactic acid paper.

[0114] Example 2

[0115] The method is basically the same as Example 1, except that in step (3), the modified PLA fiber is 10 parts and the wood fiber is 90 parts.

[0116] Example 3

[0117] The method is basically the same as Example 1, except that in step (1), the toughening agent is ethylene-butyl acrylate-glycidyl methacrylate copolymer; in step (3), the modified PLA fiber is 15 parts and the wood fiber is 85 parts.

[0118] Example 4

[0119] The method is basically the same as Example 1, except that in step (1), the toughening agent is ethylene-butyl acrylate-glycidyl methacrylate copolymer; in step (3), the modified PLA fiber is 10 parts and the wood fiber is 90 parts.

[0120] Example 5

[0121] The method is basically the same as Example 1, except that in step (1), the toughening agent is ethylene-1-octene copolymer.

[0122] Example 6

[0123] The method is basically the same as Example 1, except that in step (1), the mass ratio of PLA to toughening agent poly(butylene adipate / terephthalate) is 0.05:1.

[0124] Comparative Example 1

[0125] The method is basically the same as Example 1, except that step (1) in Example 1 is omitted, and the details are as follows:

[0126] (1) Chloroform and acetone are mixed in a mass ratio of 2:1 to prepare a spinning solution, PLA is dissolved in the spinning solution, and a spinning solution with a concentration of 5% is prepared; the obtained spinning solution is poured into a spinning tube of an electrospinning machine, and a roller is used to collect the spinning solution; wherein the spinning tube needle diameter of the electrospinning machine is 0.9 mm, the spinning voltage is 25 kV, the pole distance is 15 cm, the flow rate is 0.1 mL / h, and the collection roller speed is 2000 r / min, thereby obtaining PLA fibers.

[0127] (3) The length of the PLA fiber obtained in step (1) is about 3 mm, and the length of the wood fiber is about 3 mm. 5 parts of the PLA fiber and 95 parts of the wood fiber are mixed evenly by a hydraulic pulping method, and then passed through a 60-mesh standard sieve to form a wet paper blank, and then subjected to pulping, sheeting, wet pressing, and hot pressing, wherein the pulp mass fraction is 0.2%, the hot pressing temperature is 168° C. to 173° C., the hot pressing pressure is 6 MPa, and the hot pressing time is 3 min, to obtain polylactic acid paper.

[0128] Comparative Example 2

[0129] The method is basically the same as Example 1, except that the PLA in step (1) is replaced by an equal amount of PS (polystyrene), step (1) produces a modified PS masterbatch, step (2) produces a modified PS fiber, and step (3) produces a modified PS paper.

[0130] Comparative Example 3

[0131] The method is basically the same as Example 1, except that the toughening agent in step (1) is replaced by an equal amount of polyolefin elastomer.

[0132] Comparative Example 4

[0133] 95 parts of wood fibers with a length of about 3 mm, 4.5 parts of PLA and 0.5 parts of toughening agent poly(butylene adipate / terephthalate) were mixed evenly, and then passed through a 60-mesh standard sieve to form a wet paper blank, and then pulped, sheeted, wet pressed and hot pressed, wherein the pulp mass fraction was 0.2%, the hot pressing temperature was 168°C to 173°C, the hot pressing pressure was 6MPa, and the hot pressing time was 3min, to obtain polylactic acid paper.

[0134] Comparative Example 5

[0135] The method is basically the same as Example 1, except that step (2) in Example 1 is omitted, and in step (3), 5 parts of modified PLA masterbatch and 95 parts of wood fiber are directly mixed evenly by hydraulic pulping, and then screened for papermaking.

[0136] Comparative Example 6

[0137] The wood fiber is mixed evenly by hydraulic pulping, and then passed through a 60-mesh standard sieve to form a wet paper blank, and then subjected to pulping, sheeting, wet pressing, and hot pressing, wherein the pulp mass fraction is 0.2%, the hot pressing temperature is 168°C to 173°C, the hot pressing pressure is 6MPa, and the hot pressing time is 3min, to obtain wood fiber paper.

[0138] The performance tests of the papers prepared in the examples and comparative examples were carried out according to GB / T 22898-2008 "Determination of tensile strength of paper and paperboard - Constant rate tensile method (100 mm / min)" and GB / T 457-2008 "Determination of folding endurance of paper and paperboard". The test results are shown in Table 1.

[0139] Table 1

[0140] Group Tensile strength / Mpa <![CDATA[Bulk density / g·cm -1 > Folding endurance / lg n Example 1 27.47 0.67 3.18 Example 2 42.79 0.76 2.97 Example 3 31.54 0.72 2.13 Example 4 46.13 0.74 3.42 Example 5 24.21 0.64 2.84 Example 6 21.85 0.71 2.71 Comparative Example 1 20.35 0.65 1.89 Comparative Example 2 10.82 0.65 0.94 Comparative Example 3 25.74 0.68 2.05 Comparative Example 4 21.29 0.61 1.73 Comparative Example 5 14.71 0.63 1.32 Comparative Example 6 12.46 0.69 1

[0141] As shown in Table 1, compared with the comparative example, the tensile strength, tightness and folding resistance of the modified polylactic acid paper prepared in the embodiment are higher; and compared with the pure wood fiber paper prepared in comparative example 6, the folding resistance of the modified polylactic acid paper prepared in the embodiment is more than twice that of the pure wood fiber paper prepared in comparative example 6. In comparative example 4, although PLA and toughening agent polybutylene adipate / terephthalate are also used, they are directly mixed and modified, and the mechanical properties and folding resistance of the paper are limitedly improved; in comparative example 5, when the modified PLA masterbatch is directly mixed with wood fiber without spinning step, PLA aggregates, resulting in uneven thickness of the finished paper, and the mechanical properties and folding resistance of the paper are also limitedly improved.

[0142] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0143] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A polylactic acid packaging material, characterized in that: It comprises a modified polylactic acid fiber material and wood fiber, wherein the mass ratio of the modified polylactic acid fiber material to the wood fiber is (0.1-0.15):1; the lengths of the modified polylactic acid fiber material and the wood fiber are independently 1 mm to 10 mm; The preparation of the modified polylactic acid fiber material comprises the following steps: The polylactic acid is modified by a toughening agent to obtain a modified polylactic acid masterbatch; the toughening agent is selected from ethylene-butyl acrylate-glycidyl methacrylate copolymer; the mass ratio of the toughening agent to the polylactic acid is (0.1-0.15):1; The modification comprises the following steps: After the polylactic acid and the toughening agent are mixed, melt extrusion and granulation are performed in sequence; The modified polylactic acid masterbatch is spun to obtain a modified polylactic acid fiber material.

2. The polylactic acid packaging material according to claim 1, characterized in that: The mass ratio of the toughening agent to the polylactic acid is (0.1-0.12):

1.

3. The polylactic acid packaging material according to claim 1 or 2, characterized in that: The melt extrusion is performed using a twin-screw extruder.

4. The polylactic acid packaging material according to claim 1 or 2, characterized in that: The solvent in the spinning is selected from at least one of chloroform and acetone.

5. A method for preparing a polylactic acid packaging material, characterized in that: The following steps are involved: The polylactic acid is modified by a toughening agent to obtain a modified polylactic acid masterbatch; the toughening agent is selected from ethylene-butyl acrylate-glycidyl methacrylate copolymer; the mass ratio of the toughening agent to the polylactic acid is (0.1-0.15):1; The modification comprises the following steps: After the polylactic acid and the toughening agent are mixed, melt extrusion and granulation are performed in sequence; Spinning the modified polylactic acid masterbatch to obtain a modified polylactic acid fiber material; The modified polylactic acid fiber material and wood fiber are mixed for papermaking, and the mass ratio of the modified polylactic acid fiber material to the wood fiber is (0.1-0.15):1.