Modified cake meal protein-based degradable film material as well as preparation method and application thereof

Abstract

The invention discloses a modified cake meal protein-based degradable membrane material as well as a preparation method and application thereof. The membrane material is prepared from the following raw materials: a modifier and a cake meal protein solution, the modifier is prepared from the following raw materials: aryl diazacyclohexane and a three-arm star s-P (NIPAM-co-DMAM); the modifying agent and the cake protein form a three-dimensional cross-linked network structure through an electric field auxiliary curing technology, the prepared membrane material has excellent mechanical properties and controllable degradation characteristics, meanwhile, low-temperature efficient forming is achieved, production energy consumption is remarkably reduced, and an innovative solution is provided for high-value utilization of agricultural waste.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable materials technology, specifically relating to a modified cake protein-based biodegradable membrane material, its preparation method, and its application. Background Technology

[0002] Traditional plastic packaging films are typically made from petroleum-based polymers (such as polyethylene and polypropylene). While these materials possess excellent mechanical properties and processing characteristics, their non-degradability leads to serious "white pollution" problems. With increasing environmental protection requirements, bio-based biodegradable materials (such as starch-based and PLA films) are gaining attention, but existing technologies still have significant drawbacks: natural polymers (such as starch and cellulose) lack sufficient mechanical strength and have poor water resistance, while synthetic biodegradable materials (such as PLA) are expensive and require specific composting conditions to degrade. Furthermore, traditional protein-based film materials often employ thermosetting or chemical cross-linking processes, which are not only energy-intensive (usually requiring heating above 100°C), but the residue of cross-linking agents (such as glutaraldehyde) may also limit their application in the food and medical fields. In recent years, protein-based membrane materials made from agricultural by-products (such as camellia oil cake and soybean cake) have become a research hotspot due to their renewability and biodegradability. However, protein membranes prepared by existing technologies generally suffer from the following problems: unmodified cake protein membranes have poor mechanical properties (tensile strength is usually <10MPa) and insufficient moisture resistance (water absorption rate >50%). Furthermore, traditional curing processes rely on high-temperature treatment, which can easily lead to protein denaturation and affect film-forming performance. Although some studies have shown that adding synthetic polymers (such as PVA) can improve mechanical properties through blending modification, this sacrifices the material's complete biodegradability.

[0003] Therefore, it is urgent to develop a modified cake protein-based membrane material that combines high strength, controllable degradation characteristics, and low-energy preparation process. Summary of the Invention

[0004] This invention aims to address at least one of the technical problems existing in the prior art. To this end, this invention proposes a modified oilseed meal protein-based biodegradable membrane material and its preparation method, which can significantly improve the mechanical properties and water resistance of the protein-based membrane material, while simultaneously achieving controllable adjustment of the material's degradation performance. This invention, through innovative electric field-assisted curing technology and the synergistic effect of novel modifiers, solves the problem of insufficient mechanical strength in traditional protein-based membranes while maintaining the material's complete biodegradability.

[0005] According to a first aspect of the present invention, a modified oilseed meal protein-based biodegradable membrane material is provided, wherein the raw materials for preparing the modified oilseed meal protein-based biodegradable membrane material include: a modifier and an oilseed meal protein solution.

[0006] According to some embodiments of the present invention, the oilseed meal protein includes at least one of camellia oilseed meal, tung oilseed meal, litsea cubeba oilseed meal, and soybean meal.

[0007] According to some embodiments of the present invention, the mass concentration of the protein in the oilseed cake is not less than 99%.

[0008] According to a second aspect of the present invention, a method for preparing a modified oilseed meal protein-based biodegradable membrane material is provided, comprising: mixing the modifier and the oilseed meal protein solution, removing impurities, and then performing voltage molding.

[0009] According to some embodiments of the present invention, the voltage for voltage shaping is 0.5-5V / s.

[0010] According to some embodiments of the present invention, the voltage forming time is 0.5-2 hours.

[0011] A voltage range of 0.5-5V / s allows for precise control of the electrochemical reduction rate. Lower voltages (0.5-1V / s) are suitable for achieving deep crosslinking with a high grafting degree of 10-15%, while higher voltages (3-5V / s) meet the rapid molding requirements of 5-8% grafting degree. Combined with a time window of 0.5-2 hours, the crosslinking degree fluctuation can be controlled within ±1.5%, significantly better than the ±5% fluctuation range of traditional thermosetting. Secondly, it completely avoids protein denaturation caused by high temperatures, and simultaneously reduces the porosity of the membrane material through simultaneous ultrasonic treatment. Furthermore, it can meet the requirements for rapid through-curing of 0.1mm films and also achieve deep and uniform crosslinking of 0.5mm thick plates.

[0012] According to some embodiments of the present invention, the molar ratio of the modifier to the cake protein solution is 1:2 to 5.

[0013] According to some embodiments of the present invention, the method for preparing the modifier includes: dispersing the aryldiacyclohexane and the three-armed star sP (NIPAM-co-DMAM), reacting them, and then removing impurities to obtain the modifier.

[0014] The raw materials for preparing the modifier include: aryldiazacyclohexane and three-armed star-shaped SP (NIPAM-co-DMAM).

[0015] Three-armed star-shaped SP (NIPAM-co-DMAM) serves as a key modifier. Its molecular structure, composed of a three-armed star topology of poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide), plays multiple roles during electrocuring. The three arms of the star structure contain abundant active groups, which can covalently crosslink with carbene radicals generated from the decomposition of aryldiazacyclohexane under an electric field, forming a three-dimensional network structure that significantly improves the mechanical strength of the membrane material (tensile strength increases by more than 30%). NIPAM (N-isopropylacrylamide) imparts temperature responsiveness to the polymer, while DMAM (N,N-dimethylacrylamide) provides hydrophilicity. The copolymerization of the two optimizes the swelling behavior of the protein-based membrane, reducing water vapor permeability.

[0016] The steric hindrance effect of the star structure can guide the reduction-oxidation pathway of aryldiazacyclohexane, accelerate the conversion of diazonium intermediates into carbene radicals, and enable the cross-linking reaction to be completed efficiently. The flexible segments of the three-arm structure can be inserted between the protein molecules in the cake, and enhance the protein-polymer interface binding through hydrogen bonding and hydrophobic interactions, avoid phase separation, and finally form a uniform membrane material.

[0017] According to some embodiments of the present invention, the temperature of the reaction is 70–80°C.

[0018] According to some embodiments of the present invention, the molar ratio of the aryldiacyclohexane to the three-armed star sP (NIPAM-co-DMAM) is 1:1 to 2.

[0019] According to some embodiments of the present invention, the aryldiacyclohexane includes 4,9-diacyclohexane[2.2.2.2]decane.

[0020] According to a third aspect of the present invention, a method for preparing a modified oilseed meal protein-based biodegradable membrane material is provided, wherein the raw materials for preparing the agricultural mulch film include the modified oilseed meal protein-based biodegradable membrane material.

[0021] The modified oilseed cake protein-based biodegradable membrane material obtained by this invention exhibits high curing efficiency and a controllable process. Precise control of the degree of cross-linking of protein molecules can be achieved by precisely adjusting the voltage (0.5–5 V / s) and activation time. The electropolymerization reaction has instant start-stop characteristics; cross-linking terminates immediately upon voltage interruption, avoiding the over-cross-linking problem caused by temperature inertia in traditional thermosetting processes. Simultaneously, this method can achieve efficient curing directly in heterogeneous oilseed cake protein suspensions, expanding the processing applicability of bio-based materials. Using oil processing byproducts (protein content >99%) such as camellia oil cake and soybean cake as raw materials, the covalent bonding of the modifier transforms oilseed cake protein, originally intended as feed or waste, into a material with excellent mechanical properties.

[0022] Unless otherwise specified, the term "about" in this invention actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0023] Unless otherwise specified, "between" in this invention includes the number itself, for example, "between 2 and 3" includes the endpoint values ​​2 and 3.

[0024] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Detailed Implementation

[0025] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0026] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0027] In the examples, the camellia oil cake and meal were purchased from Zhejiang Jiusheng Camellia Oil Technology Co., Ltd.

[0028] The CAS number for aryldiazacyclohexane (4,9-diazacyclohexane[2.2.2.2]decane) is 1235576-70-1.

[0029] The three-armed star-shaped SP (NIPAM-co-DMAM) was purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0030] Example 1

[0031] This embodiment provides a modified oilseed meal protein-based biodegradable membrane material, the specific steps of which are as follows:

[0032] Preparation of Camellia oleifera cake protein solution: Take 20g of Camellia oleifera cake protein (purity >99%), add 80mL of deionized water to prepare a 20%wt solution, and stir continuously until uniform; add 0.1g of urea, stir in a 50℃ water bath until completely dissolved, add 0.5g of sodium carboxymethyl cellulose (thickening agent), and stir continuously for 30min to obtain the Camellia oleifera cake protein aqueous solution;

[0033] Preparation of the modifier: 0.67 g of aryldiacyclohexane: 4,9-diacyclohexane [2.2.2.2]decane and 1.33 g of three-arm star-shaped SP (NIPAM-co-DMAM) were dissolved in 15 mL of ethanol, refluxed at 75 °C for 1 h, and the solvent was removed by rotary evaporation;

[0034] Mix 10g of oilseed meal protein aqueous solution with 2g of modifier, sonicate for 10min to remove bubbles, inject into a mold, apply 2V / s DC voltage for 0.5h to cure and form a modified oilseed meal protein-based biodegradable membrane material.

[0035] Example 2

[0036] This embodiment provides a modified oilseed meal protein-based biodegradable membrane material, the specific steps of which are as follows:

[0037] Preparation of aqueous solution of camellia seed cake protein: Take 15g of camellia seed cake protein (purity >99%), add 85mL of deionized water to prepare a 15% suspension; add 0.075g of urea (0.5%), stir in a 50℃ water bath until completely dissolved, add 0.375g of sodium carboxymethyl cellulose (thickener), and continue stirring for 30min to obtain aqueous solution of camellia seed cake protein.

[0038] Preparation of the modifier: Aryldiazacyclohexane and three-armed star-shaped SP (NIPAM-co-DMAM) were dissolved in ethanol at a mass ratio of 1:2, refluxed at 75°C for 1 h, and the solvent was removed by rotary evaporation.

[0039] Mix 10g of oilseed meal protein aqueous solution with 2g of modifier, sonicate for 10min to remove bubbles, inject into a mold, apply 2V / s DC voltage for 0.5h to cure and form a modified oilseed meal protein-based biodegradable membrane material.

[0040] Example 3

[0041] This embodiment provides a modified oilseed meal protein-based biodegradable membrane material, the specific steps of which are as follows:

[0042] Preparation of aqueous solution of camellia seed cake protein: Take 20g of camellia seed cake protein (purity >99%), add 80mL of deionized water to prepare a 20% suspension; add 0.1g of urea (0.5%), stir in a 50℃ water bath until completely dissolved, add 0.5g of sodium carboxymethyl cellulose (thickener), and continue stirring for 30min to obtain aqueous solution of camellia seed cake protein.

[0043] Preparation of the modifier: Aryldiazacyclohexane and three-armed star-shaped SP (NIPAM-co-DMAM) were dissolved in ethanol at a mass ratio of 1:1, and the mixture was refluxed at 75°C for 1.5 h. The solvent was then removed by rotary evaporation.

[0044] Mix 10g of oilseed meal protein aqueous solution with 2g of modifier, sonicate for 10min to remove bubbles, inject into a mold, apply 2V / s DC voltage for 0.5h to cure and form a modified oilseed meal protein-based biodegradable membrane material.

[0045] Example 4

[0046] This embodiment provides a modified oilseed meal protein-based biodegradable membrane material, the specific steps of which are as follows:

[0047] Preparation of aqueous solution of camellia seed cake protein: Take 20g of camellia seed cake protein (purity >99%), add 80mL of deionized water to prepare a 20% suspension; add 0.1g of urea (0.5%), stir in a 50℃ water bath until completely dissolved, add 0.5g of sodium carboxymethyl cellulose (thickener), and continue stirring for 30min to obtain aqueous solution of camellia seed cake protein.

[0048] Preparation of the modifier: Aryldiazacyclohexane and three-armed star-shaped SP (NIPAM-co-DMAM) were dissolved in ethanol at a mass ratio of 1:2, refluxed at 75°C for 1 h, and the solvent was removed by rotary evaporation.

[0049] Mix 10g of oilseed meal protein aqueous solution with 2g of modifier, sonicate for 10min to remove bubbles, inject into a mold, apply 5V / s DC voltage for 0.5h to cure and form a modified oilseed meal protein-based biodegradable membrane material.

[0050] Example 5

[0051] This embodiment provides a modified oilseed meal protein-based biodegradable membrane material, the specific steps of which are as follows:

[0052] Preparation of tung oil cake protein aqueous solution: Take 20g of tung oil cake protein (purity >99%), add 80mL of deionized water to prepare 20%, and stir continuously until uniform; add 0.1g of urea (0.5%), stir in a 50℃ water bath until completely dissolved, add 0.5g of sodium carboxymethyl cellulose (thickener), and stir continuously for 30min to obtain tung oil cake protein aqueous solution.

[0053] Preparation of the modifier: Aryldiazacyclohexane and three-armed star-shaped SP (NIPAM-co-DMAM) were dissolved in ethanol at a mass ratio of 1:2, refluxed at 75°C for 1 h, and the solvent was removed by rotary evaporation.

[0054] Mix 10g of oilseed meal protein aqueous solution with 2g of modifier, sonicate for 10min to remove bubbles, inject into a mold, apply 2V / s DC voltage for 0.5h to cure and form a modified oilseed meal protein-based biodegradable membrane material.

[0055] Comparative Example 1

[0056] This comparative example prepared a modified cake protein-based biodegradable membrane material. The difference between this comparative example and Example 1 is that cyclohexane was used instead of aryldiacyclohexane, while the other conditions were the same.

[0057] Comparative Example 2

[0058] This comparative example prepared a modified cake protein-based biodegradable membrane material. The difference between this comparative example and Example 1 is that N,N-dimethylacrylamide was used instead of the three-armed star-shaped SP (NIPAM-co-DMAM), while the other conditions were the same.

[0059] Comparative Example 3

[0060] This comparative example prepared a modified cake protein-based biodegradable membrane material. The difference between this comparative example and Example 1 is that the heating method (temperature 70°C) is used instead of the DC voltage molding method, while the other conditions are the same.

[0061] Comparative Example 4

[0062] This comparative example prepared a modified oilseed meal protein-based biodegradable membrane material. The difference between this comparative example and Example 1 is that no oilseed meal protein component was added, while the other conditions were the same.

[0063] Test example:

[0064] ① The selection of mulch film takes into account tensile strength, water vapor transmittance, light transmittance, and the number of days required for 100% natural degradation, so as to facilitate crop growth and subsequent natural degradation.

[0065] Five film specimens were prepared for each process condition. The tensile properties of the biodegradable film were tested in accordance with the national standard "Test Method for Tensile Properties of Plastic Films (GB 13022-1991)".

[0066] The transmittance of the film was measured using a UV spectrophotometer. The sample was cut into 1cm × 1cm pieces, and its thickness was measured. The cut sample was then placed against one side of a cuvette and placed in the instrument. The wavelength range was set to 200–800 nm. A blank cuvette was used as a control, and two parallel sets of samples were prepared.

[0067] This test case examined the performance of the products obtained from Examples 1-5 and Comparative Examples 1-3. Traditional polyethylene mulch film (0.025 mm thick) was used in this test, and the products obtained from the above examples and comparative examples were compared with them. The test results are shown in Table 1.

[0068] Table 1. Performance Tests of Biodegradable Films (Mortar Film Application)

[0069]

[0070] In Comparative Example 1, cyclohexane was used to replace aryldiazacyclohexane. Although the two have similar structures and both contain cyclohexane-like structures, aryldiazacyclohexane contains a nitrogen atom in its heterocyclic cyclohexane structure. The reactivity and reaction pathway are significantly different. In the subsequent low-voltage pressurized reaction, the relevant reaction cannot occur and covalent bonds cannot be formed. Therefore, the product in Comparative Example 1 cannot be formed, and its mechanical properties cannot be detected.

[0071] In Comparative Example 2, N,N-dimethylacrylamide was used to replace the three-armed star sP (NIPAM-co-DMAM). Although the two have similar structures and both contain amide structures, the three-armed star sP (NIPAM-co-DMAM) has a more complex spatial structure, which directly affects the reactivity and reaction pathway of the relevant chemical groups. Compared with N,N-dimethylacrylamide, the reaction mode is significantly different. In the subsequent low-voltage pressurization reaction, the relevant reaction cannot occur, and covalent bonds cannot be formed. Therefore, the product in Comparative Example 1 could not be molded, and its mechanical properties could not be detected.

[0072] In Comparative Example 3, heating (temperature 70℃) was used instead of DC voltage molding. Because the product responds to the current, it undergoes a related reaction to form a cross-linked network structure. However, when heating is used instead, the components cannot undergo the related reaction to form covalent bonds, resulting in no connection between the components and making it impossible to detect the relevant properties of the product.

[0073] In Comparative Example 4, no cake protein component was added, which reduced the activity of the product during the reaction process, preventing it from reacting fully and forming a cross-linked network structure. As a result, the mechanical properties were worse than those of the Example.

Claims

1. A modified oilseed meal protein-based biodegradable membrane material, characterized in that, The raw materials for preparing the modified oilseed meal protein-based biodegradable membrane material include: a modifier and an oilseed meal protein solution; The raw materials for preparing the modifier include: aryldiazacyclohexane and three-armed star-shaped SP (NIPAM-co-DMAM).

2. The modified oilseed meal protein-based biodegradable membrane material according to claim 1, characterized in that, The oilseed meal protein includes at least one of camellia oilseed meal, tung oilseed meal, litsea cubeba oilseed meal, and soybean meal.

3. A method for preparing a modified oilseed meal protein-based biodegradable membrane material as described in claim 1 or 2, characterized in that, include: The modifier and the cake protein solution are mixed, impurities are removed, and then voltage molding is performed.

4. The preparation method according to claim 3, characterized in that, The voltage for voltage shaping is 0.5-5V / s.

5. The preparation method according to claim 3, characterized in that, The voltage forming time is 0.5-2 hours.

6. The preparation method according to claim 3, characterized in that, The molar ratio of the modifier to the cake protein solution is 1:2 to 5.

7. The preparation method according to claim 3, characterized in that, The method for preparing the modifier includes: dispersing the aryldiacyclohexane and the three-armed star sP (NIPAM-co-DMAM), reacting them, and then removing impurities to obtain the modifier.

8. The preparation method according to claim 7, characterized in that, The reaction temperature is 70–80°C.

9. The preparation method according to claim 7, characterized in that, The mass ratio of the aryldiazacyclohexane to the three-armed star sP (NIPAM-co-DMAM) is 1:1 to 2.

10. An agricultural mulch film, characterized in that, The raw materials for preparing the agricultural mulch film include the modified oilseed meal protein-based biodegradable membrane material as described in claim 1 or 2.

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