High-strength and high-toughness cellulose-based bioplastic as well as preparation method and application thereof

Abstract

The invention discloses a high-strength and high-toughness cellulose-based bioplastic, and a preparation method and application thereof, and belongs to the field of bio-based plastics. A small amount of a high-boiling-point solvent is used as a plasticizer of cellulose and derivatives thereof, the plasticizer is used as a solvent of a modifier and a cross-linking agent, a large amount of hydroxyl groups on the cellulose and the derivatives thereof are used as reaction active points, and the crosslinked cellulose containing the plasticizer is prepared through thermoplastic processing by means of low-temperature chemistry; soaking the crosslinked cellulose in a phase separation solution to remove the plasticizer and induce microphase separation of the crosslinked cellulose, and regulating and controlling a microphase separation structure through cellulose chemical structure regulation and control, microphase separation conditions and a post-treatment method. The cellulose content of the obtained microphase separation cellulose is greater than or equal to 80wt%, the tensile strength is greater than or equal to 60MPa, the elongation at break is greater than or equal to 40%, and the microphase separation cellulose has the characteristics of high strength and high toughness. The high-strength and high-toughness cellulose-based bioplastic can be prepared by combining thermoplastic processing with post-treatment, the preparation method is simple, the performance is excellent, and industrial production is easy to realize.

Description

Technical Field

[0001] The present invention belongs to the field of bio-based plastics, and specifically relates to a high-strength and high-toughness cellulose-based bio-plastic, a preparation method and an application thereof. Background Art

[0002] To date, the world's synthetic plastic production has exceeded 8 billion tons. However, synthetic plastics are mainly petroleum-based plastics, which has seriously aggravated the problem of global oil resource depletion. It is predicted that by 2025, synthetic polymers will consume 20% of the world's oil resources. Bio-based materials are renewable, and using bio-based raw materials to prepare high-performance bio-based plastics is one of the effective means to alleviate the depletion of oil resources.

[0003] Cellulose is the most abundant non-food bio-based polymer on earth. It has the advantages of abundant sources, renewable, high modulus, and low price. It is an ideal material to replace petroleum-based polymers. However, the cellulose backbone is composed of rigid β-D-pyranose groups rich in hydroxyl groups. The rigid backbone, high crystallinity, and high-density hydrogen bonds make the melting temperature (T m ) is very high, making it difficult to process by thermoplastics, and its processing and molding relies on solution processing, which is difficult to apply on a large scale. In addition, the rigid main chain, high crystallinity and high-density hydrogen bonds will severely limit the mobility of the cellulose chain segments, resulting in poor toughness of cellulose-based plastics. The tensile strength of the regenerated cellulose film prepared by casting using ionic liquids as solvents is usually 60 to 120 MPa, while the elongation at break is only 6 to 9%. The addition of plasticizers and chemical modifications can give cellulose and its derivatives certain thermoplastic processing characteristics and improve their toughness, but will significantly reduce their strength and cause problems such as plasticizer migration and sensitivity to water. Therefore, based on reasonable structural design, the preparation of high-strength and high-toughness cellulose-based plastics by thermoplastic processing has important scientific value and practical significance. Summary of the invention

[0004] In order to solve the problems in the prior art, the present invention provides a high-strength and high-toughness cellulose-based bioplastic, a preparation method and an application. A small amount of high-boiling point solvent is used as a plasticizer for cellulose and its derivatives, and the plasticizer is also used as a solvent for a modifier and a cross-linking agent. A large number of hydroxyl groups on cellulose and its derivatives are used as reactive sites. With the help of low-temperature chemistry, cross-linked cellulose containing plasticizer is prepared by thermoplastic processing; then the cross-linked cellulose is immersed in a phase separation liquid to remove the plasticizer and induce microphase separation of the cross-linked cellulose, and the microphase separation structure is regulated by regulating the cellulose chemical structure, microphase separation conditions and post-treatment methods. The obtained microphase-separated cellulose has a cellulose content of ≥80wt%, a tensile strength of ≥60MPa and an elongation at break of ≥40%, showing high strength and high toughness characteristics. The high-strength and high-toughness cellulose-based bioplastic can be prepared by thermoplastic processing combined with post-treatment, and the preparation method is simple, the performance is excellent and it is easy to realize industrial production.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A high-strength and high-tenacity cellulose-based bioplastic, wherein the cellulose content of the high-strength and high-tenacity cellulose-based bioplastic is ≥80wt%, the tensile strength is ≥65MPa, and the elongation at break is ≥40%.

[0007] Furthermore, the high-strength and high-toughness cellulose-based bioplastic is a microphase-separated cross-linked polymer, which is prepared from cellulose or its derivatives, ethyl isocyanate acrylate, a modifier and a cross-linking agent through microphase separation.

[0008] Furthermore, the cellulose or its derivative is one or a combination of two or more selected from the group consisting of plant cellulose, microcrystalline cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose and cellulose acetate; the cross-linking agent is one or a combination of two or more selected from the group consisting of hexa(3-mercaptopropionic acid) dipentaerythritol ester, tetra(3-mercaptopropionic acid) pentaerythritol ester, tri(3-mercaptopropionic acid) trimethylolpropane ester, ethylene glycol dimercaptoacetate, 1,4-butanedithiol and 1,6-hexanethiol; the modifier is one or a combination of two or more selected from the group consisting of n-dodecyl mercaptan, n-tetradecyl mercaptan, 1-hexyl mercaptan, 2-ethylhexyl mercaptan, n-butyl isocyanate and ethyl isocyanate.

[0009] Furthermore, the content of cellulose or its derivatives is 80-95wt%, the content of ethyl isocyanate acrylate is 3-10wt%, the content of the modifier is 0-10wt%, and the content of the crosslinking agent is 2-10wt%.

[0010] A method for preparing high-strength and high-toughness cellulose-based bioplastic, the specific steps are as follows:

[0011] (1) adding a solvent-based plasticizer to cellulose or its derivative powder, and mechanically stirring for 3 to 5 minutes to obtain initially plasticized cellulose;

[0012] (2) adding the cellulose preliminarily plasticized in step (1) into an internal mixer or an extruder, stirring to uniformly plasticize the cellulose, and then sequentially adding ethyl isocyanate acrylate, a crosslinking agent, and a modifier, stirring each time a substance is added to achieve uniform blending and in-situ modification;

[0013] (3) hot pressing the blend obtained in step (2) to obtain sheet-like cross-linked cellulose; then immersing the cross-linked cellulose in a phase separation liquid to cause micro-phase separation, and drying at room temperature and in a vacuum oven to obtain a micro-phase-separated cellulose-based plastic.

[0014] Furthermore, in step (1), the solvent-based plasticizer is one or a combination of two or more selected from the group consisting of dimethyl sulfoxide, ionic liquids (1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate, 1-allyl-3-methylimidazolium chloride), and triethyl phosphate, and the mass ratio of cellulose to the solvent-based plasticizer is 100:(40-100).

[0015] Furthermore, in step (2), the temperature of the internal mixer or extruder is 60 to 90° C., the rotation speed is 50 to 80 rpm, the stirring time for uniform plasticization is 3 to 10 min, the stirring time after adding ethyl isocyanate acrylate is 10 to 20 min, the stirring time after adding the crosslinking agent is 10 to 20 min, and the stirring time after adding the modifier is 10 to 20 min.

[0016] Furthermore, in step (3), the hot pressing temperature is 100-150° C., the hot pressing time is 10-30 min, the phase separation liquid is one or a combination of two or more of water, methanol, ethanol, and dimethylacetamide, the immersion time is 0.5-3 hours, the immersion times are 3-5 times, the room temperature drying time is 6-24 hours, and the vacuum oven drying time is 6-24 hours.

[0017] The above-mentioned application of a high-strength and high-toughness cellulose-based bioplastic, the cellulose-based bioplastic can replace petroleum-based plastics and be used as packaging materials, electrical appliance housings and structural materials.

[0018] Those skilled in the art may also add other optional additives as needed to obtain better performance. These additives may be selected from antioxidants, preservatives, bactericides, antistatic agents, crosslinking agents, pigments, fillers, fragrances, etc., and may be added simultaneously or separately.

[0019] Beneficial effects of the present invention:

[0020] (1) The present invention is the first to efficiently prepare cross-linked cellulose through thermoplastic processing: a small amount of solvent is used as a plasticizer for cellulose or its derivatives, and the solvent is also a solvent for the modifier and the cross-linking agent; the hydroxyl groups on cellulose and its derivatives are used as reaction active points, combined with chemical reactions that can occur at low temperatures, and cross-linked cellulose can be prepared through thermoplastic processing. This method and idea have not been reported before.

[0021] (2) The present invention is the first to prepare a cellulose-based plastic with both high strength and high deformation capacity based on a microphase separation strategy: the microphase separation strategy is mainly used for the toughening and functionalization of hydrogels, and its application in cellulose-based plastics has never been reported; the cellulose-based plastics reported so far are difficult to achieve both high strength (≥65MPa) and high deformation capacity (≥40%).

[0022] (3) The main raw materials used in the present invention are cellulose and its derivatives, which have the advantages of wide raw material sources, renewable raw materials, and low prices.

[0023] (4) The cellulose-based bioplastic prepared by the present invention has the advantages of high bio-based content, thermoplastic processing, high strength and toughness, etc. It can replace petroleum-based plastics in the fields of packaging materials, electrical housings and structural materials, and is expected to alleviate the problem of depletion of petroleum resources. DETAILED DESCRIPTION

[0024] The present invention will be further explained below in conjunction with specific implementation methods. It should be understood that the following specific implementation methods are only used to illustrate the present invention and are not used to limit the scope of the present invention. If technicians in this field make some non-essential adjustments and improvements to the present invention based on the above-mentioned contents of the present invention, they still fall within the scope of protection of the present invention.

[0025] Comparative Example 1:

[0026] The preparation method of the cast cellulose film comprises the following steps:

[0027] (1) Dissolve 25 g of hydroxyethyl cellulose in 2500 ml of deionized water and stir at room temperature for 2 h to obtain an aqueous solution of hydroxyethyl cellulose;

[0028] (2) The hydroxyethyl cellulose solution was poured into a tetrafluoroethylene petri dish, slowly dried at room temperature for two days, and then dried in a vacuum oven at 60° C. to constant weight to obtain a hydroxyethyl cellulose membrane.

[0029] Comparative Example 2:

[0030] A method for preparing a cross-linked cellulose-based plastic in solution, comprising:

[0031] (1) adding 25 g of hydroxyethyl cellulose to 2500 ml of DMSO and stirring for 1 h to obtain a hydroxyethyl cellulose solution with a concentration of 1 w / v%; heating the solution to 60° C., adding 5 g of ethyl isocyanate acrylate (MOI) under continuous stirring, and reacting at 60° C. for 3 h to obtain an acrylated hydroxyethyl cellulose solution;

[0032] (2) adding 4 g of pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) dropwise to an acrylic acid-esterified hydroxyethyl cellulose solution at room temperature, and stirring at 1000 rpm for 2 h to obtain a gelled hydroxyethyl cellulose crosslinked body; cutting the gel into pieces, washing it four times with ethanol to remove DMSO, and drying the washed particles in an oven at 60° C. to constant weight to obtain hydroxyethyl cellulose crosslinked particles that can be hot-pressed;

[0033] (3) The hydroxyethyl cellulose cross-linked particles were hot-pressed at 140°C for 30 min to obtain a cellulose-based bioplastic film.

[0034] Comparative Example 3:

[0035] A method for preparing non-microphase-separated cellulose-based bioplastics, comprising the steps of:

[0036] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0037] (2) adding the plasticized cellulose to an internal mixer, stirring at 70°C at 60 rpm for 5 min, adding ethyl isocyanate acrylate (MOI) DMSO solution (2 g MOI, 8 g DMSO) and stirring for 20 min, then adding crosslinking agent pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) DMSO solution (1.6 g PEMP, 8 g DMSO) and stirring for 20 min;

[0038] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then drying the cross-linked cellulose at room temperature for 48 hours and in a vacuum oven at 60° C. for 48 hours to obtain a cellulose-based bioplastic.

[0039] Embodiment 1:

[0040] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0041] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0042] (2) adding the plasticized cellulose to an internal mixer, stirring at 70°C at 60 rpm for 5 min, adding ethyl isocyanate acrylate (MOI) DMSO solution (2 g MOI, 8 g DMSO) and stirring for 20 min, then adding crosslinking agent pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) DMSO solution (1.6 g PEMP, 8 g DMSO) and stirring for 20 min;

[0043] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0044] Embodiment 2:

[0045] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0046] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0047] (2) adding the plasticized cellulose to an internal mixer, stirring at 70° C. at 60 rpm for 5 min, adding a DMSO mixed solution of ethyl isocyanate acrylate (MOI) and n-butyl isocyanate (BIC) (2 g MOI, 1 g BIC, 8 g DMSO) and stirring for 20 min, then adding a DMSO solution of crosslinking agent pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) (1.6 g PEMP, 8 g DMSO) and stirring for 20 min;

[0048] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0049] Embodiment 3:

[0050] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0051] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0052] (2) adding the plasticized cellulose to an internal mixer, stirring at 70° C. and 60 rpm for 5 min, adding a DMSO solution of ethyl isocyanate acrylate (MOI) (2 g MOI, 8 g DMSO) and stirring for 20 min, and then adding a DMSO solution of crosslinking agent ethylene glycol dimercaptoacetate (EMA) (1.4 g EMA, 8 g DMSO) and stirring for 20 min;

[0053] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0054] Embodiment 4:

[0055] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0056] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0057] (2) adding the plasticized cellulose to an internal mixer, stirring at 70° C. and 60 rpm for 5 min, adding DMSO solution of ethyl isocyanate acrylate (MOI) (2 g MOI, 8 g DMSO) and stirring for 20 min, and then adding DMSO solution of crosslinking agent dipentaerythritol hexa(3-mercaptopropionate) (DHMP) (1.7 g DHMP, 8 g DMSO) and stirring for 20 min;

[0058] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0059] Embodiment 5:

[0060] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0061] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0062] (2) adding the plasticized cellulose to an internal mixer, stirring at 70° C. and 60 rpm for 5 min, adding a DMSO solution of ethyl isocyanate acrylate (MOI) (2 g MOI, 8 g DMSO) and stirring for 20 min, and then adding a DMSO solution of crosslinking agents ethylene glycol dimercaptoacetate (EMA) and dipentaerythritol hexa(3-mercaptopropionic acid) ester (DHMP) (0.7 g EMA, 0.8 g DHMP, 8 g DMSO) and stirring for 20 min;

[0063] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0064] Embodiment 6:

[0065] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0066] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0067] (2) adding the plasticized cellulose to an internal mixer, stirring at 70° C. and 60 rpm for 5 min, adding ethyl isocyanate acrylate (MOI) DMSO solution (2 g MOI, 8 g DMSO) and stirring for 20 min, then adding crosslinking agent tris(3-mercaptopropionic acid) trimethylolpropane ester (TPMP) DMSO solution (1.7 g TPMP, 8 g DMSO) and stirring for 20 min;

[0068] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0069] Embodiment 7:

[0070] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0071] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0072] (2) adding the plasticized cellulose to an internal mixer, stirring at 90° C. at 60 rpm for 4 min, adding ethyl isocyanate acrylate (MOI) DMSO solution (2 g MOI, 8 g DMSO) and stirring for 10 min, then adding crosslinking agent pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) DMSO solution (1.6 g PEMP, 8 g DMSO) and stirring for 10 min;

[0073] (3) hot pressing the above blend at 150° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0074] Embodiment 8:

[0075] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0076] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0077] (2) adding the plasticized cellulose to an internal mixer, stirring at 60 rpm for 5 min at 60° C., adding a DMSO solution of ethyl isocyanate acrylate (MOI) (2 g MOI, 8 g DMSO) and stirring for 20 min, and then adding a DMSO solution of a crosslinking agent pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) (1.6 g PEMP, 8 g DMSO) and stirring for 20 min;

[0078] (3) hot pressing the above blend at 120° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0079] Embodiment 9:

[0080] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0081] (1) Add 10 g DMSO to 25 g hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0082] (2) adding the plasticized cellulose to an internal mixer, stirring at 70° C. and 60 rpm for 5 min, adding ethyl isocyanate acrylate (MOI) DMSO solution (1 g MOI, 8 g DMSO) and stirring for 20 min, then adding crosslinking agent pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) DMSO solution (0.8 g PEMP, 8 g DMSO) and stirring for 20 min;

[0083] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0084] Embodiment 10:

[0085] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0086] (1) Add 15 g of DMSO to 25 g of hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0087] (2) adding the plasticized cellulose to an internal mixer, stirring at 70° C. and 60 rpm for 5 min, adding ethyl isocyanate acrylate (MOI) DMSO solution (2 g MOI, 5 g DMSO) and stirring for 20 min, then adding crosslinking agent pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) DMSO solution (1.6 g PEMP, 5 g DMSO) and stirring for 20 min;

[0088] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0089] Embodiment 11:

[0090] A method for preparing microphase separated cellulose-based bioplastics, comprising the steps of:

[0091] (1) Add 20 g of DMSO to 25 g of hydroxyethyl cellulose and stir with a glass rod for 3 min;

[0092] (2) adding the plasticized cellulose to an internal mixer, stirring at 70°C at 60 rpm for 5 min, adding ethyl isocyanate acrylate (MOI) DMSO solution (2 g MOI, 3 g DMSO) and stirring for 20 min, then adding crosslinking agent pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) DMSO solution (1.6 g PEMP, 3 g DMSO) and stirring for 20 min;

[0093] (3) hot pressing the above blend at 140° C. for 30 minutes to obtain sheet-like cross-linked cellulose; then soaking the cross-linked cellulose in water for 40 minutes each time for 3 times, and then drying at room temperature for 24 hours and in a vacuum oven at 60° C. for 24 hours to obtain a cellulose-based bioplastic.

[0094] Table 1 Typical properties of Comparative Examples 1 to 3 and Examples 1 to 11

[0095]

[0096]

[0097] The above results show that the cellulose material prepared by the casting method (Comparative Example 1) has lower tensile strength and elongation at break, and the cross-linked cellulose prepared by the solution method (Comparative Example 2) and the cross-linked cellulose without microphase separation (Comparative Example 3) have slightly improved mechanical properties compared with Comparative Example 1, but are still poor. Compared with the comparative example, the cross-linked cellulose with microphase separation (Examples 1 to 11) proposed in the present invention has very excellent mechanical properties, and the tensile strength and elongation at break are much higher than those of the comparative example. In addition, the cellulose-based bioplastic obtained by this method has the characteristics of high bio-based content, high strength and high toughness. By adjusting the processing conditions, the content of cross-linking components and the content of modifiers, the strength and toughness of the bioplastic can be adjusted within a certain range, but the final strength is still higher than 65MPa, and the final elongation at break is still higher than 40%.

[0098] Those skilled in the art should understand that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-strength and high-tenacity cellulose-based bioplastic, characterized in that: The high-strength and high-tenacity cellulose-based bioplastic has a cellulose content of ≥80wt%, a tensile strength of ≥65MPa, and an elongation at break of ≥40%.

2. The high-strength and high-toughness cellulose-based bioplastic according to claim 1, characterized in that: The high-strength and high-toughness cellulose-based bioplastic is a microphase-separated cross-linked polymer, which is prepared from cellulose or its derivatives, ethyl isocyanate acrylate, a modifier and a cross-linking agent through microphase separation.

3. The high-strength and high-toughness cellulose-based bioplastic according to claim 1, characterized in that: The cellulose or its derivative is one or a combination of two or more selected from the group consisting of plant cellulose, microcrystalline cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose and cellulose acetate; the cross-linking agent is one or a combination of two or more selected from the group consisting of hexa(3-mercaptopropionic acid)dipentaerythritol ester, tetra(3-mercaptopropionic acid)pentaerythritol ester, tri(3-mercaptopropionic acid)trimethylolpropane ester, ethylene glycol dimercaptoacetate, 1,4-butanedithiol and 1,6-hexaneedithiol; the modifier is one or a combination of two or more selected from the group consisting of n-dodecyl mercaptan, n-tetradecyl mercaptan, 1-hexyl mercaptan, 2-ethylhexyl mercaptan, n-butyl isocyanate and ethyl isocyanate.

4. The high-strength and high-toughness cellulose-based bioplastic according to claim 1, characterized in that: The content of cellulose or its derivatives is 80-95wt%, the content of ethyl isocyanate acrylate is 3-10wt%, the content of modifier is 0-10wt%, and the content of crosslinking agent is 2-10wt%.

5. The method for preparing a high-strength and high-tenacity cellulose-based bioplastic according to any one of claims 1 to 4, characterized in that: The specific steps are as follows: (1) adding a solvent-based plasticizer to cellulose or its derivative powder and mechanically stirring for 3 to 5 minutes to obtain initially plasticized cellulose; (2) adding the cellulose preliminarily plasticized in step (1) into an internal mixer or an extruder, stirring to uniformly plasticize the cellulose, and then sequentially adding ethyl isocyanate acrylate, a crosslinking agent, and a modifier, stirring each time a substance is added to achieve uniform blending and in-situ modification; (3) hot pressing the blend obtained in step (2) to obtain sheet-like cross-linked cellulose; The cross-linked cellulose is then immersed in a phase separation liquid to perform micro-phase separation, and then dried at room temperature and in a vacuum oven to obtain a micro-phase-separated cellulose-based plastic.

6. The method for preparing a cellulose-based bioplastic according to claim 5, characterized in that: In step (1), the solvent-based plasticizer is one or a combination of two or more of dimethyl sulfoxide, ionic liquid, and triethyl phosphate, and the mass ratio of cellulose to the solvent-based plasticizer is 100:(40-100).

7. The method for preparing a cellulose-based bioplastic according to claim 5, characterized in that: In step (2), the temperature of the internal mixer or extruder is 60 to 90° C., the rotation speed is 50 to 80 rpm, the stirring time for uniform plasticization is 3 to 10 min, the stirring time after adding ethyl isocyanate acrylate is 10 to 20 min, the stirring time after adding the crosslinking agent is 10 to 20 min, and the stirring time after adding the modifier is 10 to 20 min.

8. The method for preparing a cellulose-based bioplastic according to claim 5, characterized in that: In step (3), the hot pressing temperature is 100-150° C., the hot pressing time is 10-30 min, the phase separation liquid is one or a combination of two or more of water, methanol, ethanol, and dimethylacetamide, the immersion time is 0.5-3 hours, the immersion times are 3-5 times, the room temperature drying time is 6-24 hours, and the vacuum oven drying time is 6-24 hours.

9. Use of a high-strength and high-toughness cellulose-based bioplastic according to any one of claims 1 to 4, or a high-strength and high-toughness cellulose-based bioplastic prepared by the preparation method according to any one of claims 5 to 8, characterized in that: The cellulose-based bioplastic can replace petroleum-based plastics and be used as packaging materials, electrical appliance housings and structural materials.

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