Preparation method of degradable bio-based pressure-sensitive adhesive and environment-friendly adhesive tape product

Abstract

The invention relates to the technical field of pressure-sensitive adhesives, and discloses a preparation method of a degradable bio-based pressure-sensitive adhesive and an environment-friendly adhesive tape product, the degradable bio-based pressure-sensitive adhesive comprises the following raw materials by mass: 45%-55% of polylactic acid, 10%-20% of sodium alginate, 5%-8% of cinnamomum camphora oil, 3%-5% of vegetable tannin, 10%-18% of glycerin, 7%-15% of a natural antibacterial agent, and a solvent-free additive accounting for 1%-5% of the total weight. The natural antibacterial agent comprises cinnamon oil or tea tree oil, nitrogen or carbon dioxide is injected after the vegetable tannin is added, and the solvent-free additive adopts a starch-based drying accelerant or a chitosan substance. By adopting the solvent-free additive, the dehydration uniformity can be enhanced in the drying process, the consistency of the prepared product is improved, and the shape and performance stability of the final product are ensured through the steps of dehydration treatment and mold forming.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure-sensitive adhesives, and in particular to a preparation method of a degradable bio-based pressure-sensitive adhesive and an environmentally friendly adhesive tape product. Background Art

[0002] In today's environmentally conscious trend, biodegradable bio-based pressure-sensitive adhesives (PSA) play a key role. They adhere with minimal pressure and are easily removable without contaminating the adhered surface. These properties have led to their widespread application in packaging, labeling, healthcare, and other fields. In the packaging sector, their biodegradability helps reduce environmental pollution from packaging waste; in healthcare, their excellent adhesion and biocompatibility enable applications in drug delivery systems and wound dressings.

[0003] In terms of related technologies, natural polymers or bio-based monomers are typically used as raw materials for the production of biodegradable pressure-sensitive adhesives. These materials are widely available and biodegradable, reducing negative environmental impacts. The preparation process generally includes steps such as polymerization and additive mixing. During the drying process, the presence of solvents can make it difficult for additives to disperse evenly, resulting in uneven dehydration and affecting the consistency of the finished product. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a method for preparing a degradable bio-based pressure-sensitive adhesive and an environmentally friendly tape product, which solves the problem that the presence of solvents makes it difficult to evenly disperse additives, resulting in uneven dehydration and affecting the consistency of the finished product.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a degradable bio-based pressure-sensitive adhesive comprises the following raw materials in percentage by weight: 45% to 55% polylactic acid, 10% to 20% sodium alginate, 5% to 8% camphor oil, 3% to 5% plant tannins, 10% to 18% glycerol, 7% to 15% natural antibacterial agent and 1% to 5% solvent-free additives by total weight.

[0006] Preferably, the natural antibacterial agent includes cinnamon oil or tea tree oil, nitrogen or carbon dioxide is injected after the plant tannin is added, and the solvent-free additive is a starch-based drying accelerator or a chitosan substance.

[0007] Preferably, the method for preparing the degradable bio-based pressure-sensitive adhesive comprises the following steps:

[0008] Weighing the polylactic acid and sodium alginate, pre-treating the polylactic acid, and then placing the pre-treated polylactic acid and sodium alginate in a high-temperature mixer to melt and mix to form a preliminary solution;

[0009] gradually adding camphor oil and glycerin to the preliminary solution while continuously stirring to form a mixed solution;

[0010] After the mixed solution is cooled in the high-temperature mixer, vegetable tannin is added and the high-temperature mixer continues to stir;

[0011] After the vegetable tannins are added and stirred, a natural antimicrobial agent and nitrogen or carbon dioxide are injected simultaneously to form a final mixture;

[0012] The final mixture is dehydrated and placed in a mold for forming.

[0013] Preferably, the pretreatment comprises the following steps:

[0014] The polylactic acid is placed in a drying oven and dried at 40° C.-60° C. for 1 to 2 hours.

[0015] Preferably, when the high-temperature mixer melt-mixes the polylactic acid and sodium alginate, the temperature is 160° C.-180° C. and the stirring time is 30 to 60 minutes.

[0016] Preferably, when the camphor oil and glycerin are gradually added to the preliminary solution, the temperature remains unchanged and the solution is stirred for 10 to 20 minutes.

[0017] Preferably, the temperature in the high-temperature mixer is cooled to no more than 140° C., and when stirring is continued, the temperature is raised to -160° C. to 180° C. and stirred for 15 to 30 minutes.

[0018] Preferably, when the natural antibacterial agent and nitrogen or carbon dioxide are injected simultaneously, stirring is continued for 5 to 10 minutes, and the nitrogen or carbon dioxide injection rate is 0.1-1.0 L / min, and is continued for 5 to 10 minutes.

[0019] Preferably, the dehydration treatment comprises the following steps:

[0020] The final mixture was transferred to a ventilated drying oven and dried at 45-60°C for 2 hours for preliminary dehydration;

[0021] After initial dehydration, add 1% to 5% of solvent-free additives and stir evenly;

[0022] Then place it in a vacuum drying oven at a temperature of 30-50°C and dry it for 4-8 hours.

[0023] Preferably, the degradable bio-based pressure-sensitive adhesive environmentally friendly tape product is coated on a bio-based backing material to form a single-sided or double-sided pressure-sensitive adhesive tape.

[0024] In summary, this application has the following beneficial effects:

[0025] 1. The present invention adopts solvent-free additives to enhance the dehydration uniformity during the drying process and improve the consistency of the finished product. After the dehydration treatment and mold forming steps, the shape and performance stability of the final product are ensured.

[0026] 2. The present invention enhances the biodegradability of the material by combining polylactic acid with sodium alginate. This combination can be decomposed by microorganisms in the natural environment, reducing environmental pollution, and allowing the product to decompose naturally within a certain period of time after use, which is in line with the modern concept of sustainable development.

[0027] 3. By adding natural antibacterial agents, the biodegradable bio-based pressure-sensitive adhesive of the present invention can effectively reduce the risk of microbial reproduction. After adding plant tannins, nitrogen or carbon dioxide is injected to form a uniform bubble structure, which further enhances the antibacterial properties of the colloid and ensures the safety and applicability of the product.

[0028] 4. The biodegradable bio-based pressure-sensitive adhesive environmentally friendly tape of the present invention is coated on a bio-based backing material to form a single-sided or double-sided tape. On the basis of having good bonding performance, it reduces the impact on the environment, meets the user's needs for environmental protection and functionality, and is suitable for various applications such as packaging and handicraft production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a flow chart of the method for preparing the degradable bio-based pressure-sensitive adhesive. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] Please see the attached Figure 1 An embodiment of the present invention provides a degradable bio-based pressure-sensitive adhesive, comprising the following raw materials in percentage by weight: 45% to 55% polylactic acid, 10% to 20% sodium alginate, 5% to 8% camphor oil, 3% to 5% plant tannins, 10% to 18% glycerol, 7% to 15% natural antibacterial agent, and 1% to 5% solvent-free additives by total weight.

[0032] Specifically, polylactic acid is the main chain skeleton, which gives the colloid basic mechanical strength and biodegradability, sodium alginate provides hydrophilic regulation and adhesion properties, camphor oil and glycerin serve as flexibility regulators and plasticizing components to improve the adaptability of the bonding interface, and the introduction of plant tannins can react with polar functional groups under certain conditions to form a network structure and improve stability. Natural antibacterial agents give the surface antibacterial properties, and solvent-free additives such as starch-based drying accelerators or chitosan substances enhance the dehydration uniformity and improve the consistency of the molded product in the form of inorganic carriers or bio-based polymers during the drying process. In addition, the colloid structure does not require the use of organic solvents to assist in molding, forming a pressure-sensitive adhesive material with good initial adhesion, structural stability, biodegradability and antibacterial properties.

[0033] Natural antimicrobial agents include cinnamon oil or tea tree oil, which are injected with nitrogen or carbon dioxide after adding plant tannins, and solvent-free additives use starch-based drying accelerators or chitosan substances.

[0034] Specifically, in the process of preparing degradable bio-based pressure-sensitive adhesive, the step of injecting nitrogen or carbon dioxide after adding plant tannins can improve the physical properties and durability of the mixture. Cinnamon oil and tea tree oil, as natural antibacterial agents, have strong antibacterial properties and can effectively reduce the risk of microbial reproduction on the surface of the product, thereby improving the safety and applicability of the finished product. The injection of nitrogen or carbon dioxide forms a uniform bubble structure during the mixing process, thereby reducing the density of the material, improving flexibility, and enhancing the initial adhesion and peel strength of the adhesive. The introduction of gas promotes the uniform distribution of bubbles, which helps to improve the comprehensive performance of the pressure-sensitive adhesive and ensure that the structural integrity and durability of the material are maintained while improving the antibacterial properties. The starch-based drying accelerator and chitosan-like substances are used as solvent-free additives to enhance the uniformity of dehydration and improve the consistency of the product after molding. Specifically, the starch-based drying accelerator can accelerate the removal of water, increase the dehydration rate, reduce the drying time and energy consumption, and help maintain the uniformity of the mixture, avoid uneven drying, thereby improving the quality of the final product and enhancing its physical properties. The addition of chitosan-like substances can further improve the uniformity of the drying process, ensure the consistent evaporation rate of water in different parts, and improve the shape and consistency of the product. In addition, since chitosan itself has antibacterial properties, its addition can also enhance the antibacterial properties of the colloid and improve the safety and applicability of the product.

[0035] The preparation method of the biodegradable bio-based pressure-sensitive adhesive comprises the following steps:

[0036] Weighing the polylactic acid and sodium alginate, pre-treating the polylactic acid, and then placing the pre-treated polylactic acid and sodium alginate in a high-temperature mixer to melt and mix to form a preliminary solution;

[0037] Gradually add camphor oil and glycerin to the preliminary solution, stirring continuously, to form a mixed solution;

[0038] After the mixed solution is cooled in a high-temperature blender, vegetable tannins are added and the high-temperature blender continues to stir;

[0039] After the vegetable tannins are added and stirred, natural antimicrobial agents and nitrogen or carbon dioxide are injected to form the final mixture;

[0040] The final mixture is dehydrated and placed in a mold for forming.

[0041] Specifically, a preliminary solution is formed by melt mixing of polylactic acid and sodium alginate, which ensures the uniform dispersion of the two main components and achieves efficient mixing to ensure the physical properties of the colloid. Then, camphor oil and glycerin are gradually added as plasticizers to improve the flexibility of the final mixture, thereby improving the initial viscosity of the colloid. The addition of plant tannins not only strengthens the network structure inside the colloid, but also promotes the enhancement of intermolecular interactions through high-temperature stirring, thereby improving the stability of the material. At the same time, the step of injecting natural antibacterial agents and nitrogen or carbon dioxide helps to improve the antibacterial properties of the mixture and form a microbubble structure, reducing the density of the material, thereby enhancing its overall stiffness and applicability. The final dehydration and mold forming steps ensure the good shape and consistency of the final product, effectively guaranteeing the efficiency and stability of the manufacturing process of the degradable bio-based pressure-sensitive adhesive, and meeting the performance requirements in different application environments.

[0042] Preprocessing includes the following steps:

[0043] Place the polylactic acid in a drying oven and dry it at 40℃-60℃ for 1 to 2 hours.

[0044] Specifically, placing the polylactic acid in a drying oven helps to remove moisture and volatile substances in the polylactic acid, thereby reducing the water content of the polylactic acid, and can effectively prevent bubbles from being generated or polymer degradation caused by water vapor during the subsequent melt mixing process, thereby ensuring that the initial solution formed is uniform and has good physical properties. At the same time, during the drying process, the molecular chains of the polylactic acid will remain stable, improving the viscosity and handling performance after melt mixing, and contributing to the structural integrity and application value of the final product.

[0045] When the polylactic acid and sodium alginate are melt-mixed in a high-temperature mixer, the temperature is 160° C.-180° C. and stirred for 30 minutes to 60 minutes.

[0046] Specifically, the high-temperature mixer melt-mixes the polylactic acid and sodium alginate, which can achieve uniform fusion of the two components and ensure that the polylactic acid and sodium alginate are fully melted under high temperature conditions, thereby reducing the viscosity, improving the fluidity of the mixture, promoting mutual molecular contact and involvement, and forming a preliminary solution. At the same time, the control of the stirring time helps to ensure that bubbles are fully eliminated from the formed melt, avoid defects in the subsequent curing process, and improve the physical properties and consistency of the final product.

[0047] When camphor oil and glycerin are gradually added to the preliminary solution, the temperature is kept constant and stirring is continued for 10 to 20 minutes.

[0048] Specifically, when camphor oil and glycerin are gradually added to the preliminary solution, the temperature is kept constant and stirring is performed, which can ensure that the camphor oil and glycerin as plasticizers are uniformly dispersed in the molten mixture. Through continuous stirring, good mixing of the two plasticizers is promoted, and the fluidity and uniformity of the mixed solution are enhanced. At the same time, the constant temperature prevents thermal degradation of the material, ensures that it is beneficial to the effect of the plasticizer, and makes the colloid have better flexibility and crack resistance in the subsequent curing process, and avoids the generation of bubbles in the solution, further improving the physical properties of the final pressure-sensitive adhesive and ensuring its performance in practical applications.

[0049] After cooling in the high-temperature mixer, the temperature is not higher than 140°C, and while continuing to stir, the temperature is raised to -160°C-180°C and stirred for 15 minutes to 30 minutes.

[0050] Specifically, after cooling the mixture in the high-temperature mixer to no more than 140°C, reheating it to 160°C to 180°C and continuing to stir for 15 to 30 minutes can ensure efficient and full fusion of polylactic acid and sodium alginate. During the cooling period, the temperature reduction helps to improve the stability of the mixture and prevent polymer degradation caused by high temperature. At the same time, during the reheating and stirring stage, the fluidity of the mixture can be further improved, which helps the plasticizers, namely camphor oil and glycerin, to fully interact with polylactic acid and sodium alginate, ensuring that the product has ideal viscosity and physical properties. At the same time, stirring can effectively expel bubbles in the mixture while improving the mixing uniformity, thereby optimizing the overall quality of the final product.

[0051] When injecting natural antimicrobial agents and nitrogen or carbon dioxide simultaneously, stirring is continued for 5 to 10 minutes, and the nitrogen or carbon dioxide injection rate is 0.1–1.0 L / min for 5 to 10 minutes.

[0052] Specifically, during the simultaneous injection of the natural antimicrobial agent and nitrogen or carbon dioxide, continuous stirring is performed for 5 to 10 minutes, and the gas injection rate is controlled within the range of 0.1 to 1.0 L / min, which helps to uniformly disperse and better dissolve the antimicrobial agent. Continuous stirring ensures sufficient contact between the gas and the mixture, optimizes the distribution of the antimicrobial components, and thus improves the antimicrobial properties of the mixture. At the same time, controlling the gas injection rate can effectively introduce microbubbles, reduce the density of the mixture, and improve its overall fluidity and processing performance. The role of the gas in the mixing process also helps to improve the structural stability of the final product, ensuring that the physical properties of the product are maintained and improved during the subsequent dehydration and molding stages.

[0053] The dehydration process includes the following steps:

[0054] The final mixture was transferred to a ventilated drying oven and dried at 45-60°C for 2 hours for preliminary dehydration;

[0055] After initial dehydration, add 1% to 5% of solvent-free additives and stir evenly;

[0056] Then place it in a vacuum drying oven at a temperature of 30-50°C and dry it for 4-8 hours.

[0057] Specifically, the dehydration step first transfers the final mixture to a ventilated drying oven and performs preliminary dehydration at 45°C to 60°C for 2 hours, in order to remove most of the moisture in the mixture and reduce the time and energy consumption of subsequent vacuum drying. After the preliminary dehydration, 1% to 5% of the total weight of the final mixture is added as a solvent-free additive and stirred evenly, which can improve the stability and functionality of the mixture and ensure the uniformity and quality in subsequent vacuum drying. Finally, the final mixture is placed in a vacuum drying oven and dried at 30°C to 50°C for 4 to 8 hours, which helps to further reduce the moisture content and prevent product performance degradation due to residual moisture. At the same time, it effectively improves the physical properties and storage stability of the mixture, ensuring that the technical performance of the final product meets application requirements.

[0058] Biodegradable pressure-sensitive adhesive tape is an environmentally friendly tape product. The pressure-sensitive adhesive is coated on a bio-based backing material to form a single-sided or double-sided pressure-sensitive tape.

[0059] Specifically, the biodegradable bio-based pressure-sensitive adhesive environmentally friendly tape product forms a single-sided or double-sided pressure-sensitive tape by coating pressure-sensitive adhesive on a bio-based backing material. It has the characteristics of environmental protection and high performance, so that the tape can effectively reduce environmental pollution during use and can naturally decompose within a certain period of time, reducing the negative impact on the ecosystem. At the same time, the use of bio-based materials as the backing can ensure the stability and reliability of the product's bonding performance, and is suitable for a variety of application scenarios, such as packaging, handicraft production, etc. In addition, this tape is easy to handle after use, conforms to the modern concept of sustainable development, and meets the user's dual needs for environmental protection and functionality.

[0060] Example 1

[0061] Before starting the preparation, prepare the following percentages of raw materials: polylactic acid: 50%, sodium alginate: 15%, camphor oil: 5%, plant tannin: 5%, glycerin: 15% and natural antibacterial agent: 10%.

[0062] First, the polylactic acid is pretreated by placing it in a drying oven at 60°C for 2 hours to remove excess moisture. After the polylactic acid is dried, it is placed in a high-temperature mixer with sodium alginate to form a preliminary solution through melt mixing. The mixer is set at 180°C and the mixing time is 60 minutes.

[0063] While maintaining the temperature at 180°C, gradually add camphor oil and glycerin to the preliminary solution and continue stirring for 20 minutes to uniformly disperse the camphor oil and glycerin as plasticizers in the mixture. Afterwards, allow the mixture to cool in a high-temperature mixer to no more than 140°C, then add vegetable tannins and continue stirring for 30 minutes to fully mix.

[0064] After the plant tannins are added, natural antibacterial agents are injected at the same time, and nitrogen also needs to be injected. The stirring is continued for 10 minutes, and the nitrogen injection rate is 0.5L / min to form a final mixture. The final mixture is transferred to a ventilated drying oven, the drying temperature is set to 60°C, and it is dried for 2 hours for preliminary dehydration. After the preliminary dehydration is completed, 3% of the total weight of the final mixture is added to the solvent-free additive, and after stirring evenly, the final mixture is placed in a vacuum drying oven, the temperature is set to 50°C, and the drying time is 6 hours. Finally, the processed mixture is placed in a mold for molding to make a degradable bio-based pressure-sensitive adhesive.

[0065] Example 2

[0066] Before starting the preparation, prepare the following percentages of raw materials: polylactic acid: 45%, sodium alginate: 10%, camphor oil: 8%, plant tannin: 4%, glycerin: 18% and natural antibacterial agent: 15%.

[0067] First, the polylactic acid was pretreated by placing it in a drying oven and drying it at 50°C for 1.5 hours to remove excess moisture. After the polylactic acid was dried, it was placed in a high-temperature mixer together with sodium alginate to form a preliminary solution through melt mixing. The mixer operating temperature was set at 170°C and the stirring time was 45 minutes.

[0068] While maintaining the temperature at 170°C, gradually add camphor oil and glycerin to the preliminary solution and continue stirring for 15 minutes to uniformly disperse the camphor oil and glycerin as plasticizers in the mixture. Afterwards, allow the mixture to cool in a high-temperature mixer to no higher than 135°C, then add vegetable tannins and continue stirring for 20 minutes to fully mix.

[0069] After the plant tannins are added, natural antibacterial agents are injected at the same time, and nitrogen also needs to be injected. The stirring is continued for 8 minutes, and the nitrogen injection rate is 0.3L / min to form a final mixture. The final mixture is transferred to a ventilated drying oven, the drying temperature is set to 55°C, and it is dried for 1 hour for preliminary dehydration. After the preliminary dehydration is completed, 4% of the total weight of the final mixture is added to the solvent-free additive, and after stirring evenly, the final mixture is placed in a vacuum drying oven, the temperature is set to 40°C, and the drying time is 5 hours. Finally, the processed mixture is placed in a mold for molding to make a degradable bio-based pressure-sensitive adhesive.

[0070] Example 3

[0071] Before starting the preparation, prepare the following percentages of raw materials: polylactic acid: 55%, sodium alginate: 20%, camphor oil: 5%, plant tannin: 3%, glycerin: 10% and natural antibacterial agent: 7%.

[0072] First, the polylactic acid was pretreated by placing it in a drying oven and drying it at 60°C for 2 hours to remove excess moisture. After the polylactic acid was dried, it was placed in a high-temperature mixer together with sodium alginate to form a preliminary solution by melt mixing. The mixer operating temperature was set at 180°C and the stirring time was 60 minutes.

[0073] While maintaining a temperature of 180°C, gradually add camphor oil and glycerin to the preliminary solution and continue stirring for 20 minutes to evenly disperse the camphor oil and glycerin, which act as plasticizers, in the mixture. Afterwards, allow the mixture to cool in a high-temperature blender to no higher than 140°C. Then, add the vegetable tannins and continue stirring for 30 minutes to thoroughly mix.

[0074] After the plant tannins are added, natural antibacterial agents are injected at the same time, and nitrogen also needs to be injected. The stirring is continued for 10 minutes, and the nitrogen injection rate is 0.5L / min to form a final mixture. The final mixture is transferred to a ventilated drying oven, the drying temperature is set to 60°C, and it is dried for 2 hours for preliminary dehydration. After the preliminary dehydration is completed, 4% of the total weight of the final mixture is added to the solvent-free additive, and after stirring evenly, the final mixture is placed in a vacuum drying oven, the temperature is set to 50°C, and the drying time is 6 hours. Finally, the processed mixture is placed in a mold for molding to make a degradable bio-based pressure-sensitive adhesive.

[0075] Comparative Example 1 is different from Example 1 in that no natural antimicrobial agent is added;

[0076] Comparative Example 2 is different from Example 1 in that the polylactic acid pretreatment step is not performed;

[0077] Comparative Example 3 is different from Example 2 in that camphor oil is not added;

[0078] Comparative Example 4 is different from Example 2 in that no plant tannin is added;

[0079] Comparative Example 5 is different from Example 3 in that glycerol is not provided as a plasticizer;

[0080] Comparative Example 6 is different from Example 3 in that no subsequent dehydration treatment is performed.

[0081] Example 1, Comparative Example 1 and Comparative Example 2;

[0082] (1) Antibacterial performance test

[0083] The plate method described in the national standard "GB / T 4789.2-2016 Food Microbiology Test" was used for testing. Three samples were sliced ​​and the inhibition rates against Escherichia coli and Staphylococcus aureus were determined.

[0084] Experimental Table 1

[0085]

[0086]

[0087] (2) Mechanical strength test

[0088] According to ISO 527-2:2012 Tensile test methods for fibers and plastic materials, the tensile strength and elongation at break were determined on three samples.

[0089] Experimental Table 2

[0090] sample Tensile strength (MPa) Elongation at break (%) Example 1 22.5 370 Comparative Example 1 18.0 320 Comparative Example 2 20.0 340

[0091] (3) Flexibility test

[0092] According to ISO 178:2010, flexural test methods for plastic materials, the flexural strength of three samples was measured (Table 3).

[0093] sample Flexural strength (MPa) Example 1 15.0 Comparative Example 1 10.0 Comparative Example 2 12.5

[0094] Example 2, Comparative Example 3 and Comparative Example 4;

[0095] (1) Antibacterial performance test

[0096] The plate method described in the national standard "GB / T 4789.2-2016 Food Microbiology Test" was used for testing. Three samples were sliced ​​and the inhibition rates against Escherichia coli and Staphylococcus aureus were determined.

[0097] Experimental Table 4

[0098]

[0099]

[0100] (2) Mechanical strength test

[0101] According to ISO 527-2:2012 Tensile test methods for fibers and plastic materials, the tensile strength and elongation at break were determined on three samples.

[0102] Experimental Table 5

[0103] sample Tensile strength (MPa) Elongation at break (%) Example 2 18.0 350 Comparative Example 3 16.0 300 Comparative Example 4 17.0 320

[0104] (3) Flexibility test

[0105] The flexural strength of three samples was measured using ISO 178:2010 Plastic materials - flexural test methods.

[0106] Experimental Table 6

[0107] sample Flexural strength (MPa) Example 2 12.0 Comparative Example 3 11.0 Comparative Example 4 10.5

[0108] Example 3, Comparative Example 5 and Comparative Example 6;

[0109] (1) Antibacterial performance test

[0110] The plate method described in the national standard "GB / T 4789.2-2016 Food Microbiology Test" was used for testing. Three samples were sliced ​​and the inhibition rates against Escherichia coli and Staphylococcus aureus were determined.

[0111] Experimental Table 7

[0112]

[0113]

[0114] (2) Mechanical strength test

[0115] According to ISO 527-2:2012 Tensile test methods for fibers and plastic materials, the tensile strength and elongation at break were determined on three samples.

[0116] Experimental Table 8

[0117] sample Tensile strength (MPa) Elongation at break (%) Example 3 20.0 280 Comparative Example 5 17.0 260 Comparative Example 6 18.5 270

[0118] (3) Flexibility test

[0119] According to ISO 178:2010, Plastic materials, bending test methods, three samples were measured for bending strength test table 9

[0120] sample Flexural strength (MPa) Example 3 13.5 Comparative Example 5 11.0 Comparative Example 6 12.0

[0121] Combining Example 1 with Comparative Example 1 and Comparative Example 2 and combining Experimental Table 1, Experimental Table 2 and Experimental Table 3, it can be seen that the antibacterial inhibition rate and mechanical properties of Example 1 are significantly better than those of the comparative example samples. The addition of the natural antibacterial agent makes the inhibition rate of Example 1 reach 98%, while the inhibition rate of Comparative Example 1 is greatly reduced to 30%. The improvement of tensile strength and elongation at break also shows the effect of the pretreatment step of polylactic acid on the strength of the material;

[0122] Combining Example 2 with Comparative Examples 2 and 3 and with Experimental Tables 4, 5, and 6, it can be seen that the antibacterial performance of Example 2 far exceeds that of the comparative example samples. The addition of the natural antibacterial agent enables Example 2 to achieve 95% of the antibacterial performance. In terms of mechanical properties, although the addition of plant tannins in Comparative Example 4 brings some improvement, it is still inferior to the performance of Example 2.

[0123] Combining Example 3 with Comparative Examples 5 and 6 and with Experimental Tables 7, 8 and 9, it can be seen that Example 3 has excellent antibacterial performance, with an inhibition rate of 92%, which is higher than that of Comparative Examples 5 and 6. Although the antibacterial performance of Comparative Example 6 is improved after treatment, it is still lower than that of Example 3. In addition, Example 3 also performs well in tensile strength and flexural strength tests, indicating that the addition of glycerol is crucial to improving the flexibility and strength of the material.

[0124] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A biodegradable bio-based pressure-sensitive adhesive, characterized in that: The invention comprises the following raw materials in percentage by weight: 45% to 55% of polylactic acid, 10% to 20% of sodium alginate, 5% to 8% of camphor oil, 3% to 5% of plant tannin, 10% to 18% of glycerol, 7% to 15% of natural antibacterial agent and 1% to 5% of solvent-free additives in total weight.

2. The degradable bio-based pressure-sensitive adhesive according to claim 1, characterized in that: The natural antibacterial agent includes cinnamon oil or tea tree oil. Nitrogen or carbon dioxide is injected after the plant tannin is added. The solvent-free additive adopts a starch-based drying accelerator or a chitosan substance.

3. A method for preparing a degradable bio-based pressure-sensitive adhesive, for use in the degradable bio-based pressure-sensitive adhesive according to any one of claims 1 to 2, characterized in that: The following steps are involved: Weighing polylactic acid and sodium alginate, pre-treating the polylactic acid, and placing the sodium alginate and the pre-treated polylactic acid in a high-temperature mixer to melt and mix to form a preliminary solution; gradually adding camphor oil and glycerin to the preliminary solution while continuously stirring to form a mixed solution; After the mixed solution is cooled in the high-temperature mixer, vegetable tannin is added and the high-temperature mixer continues to stir; After the vegetable tannins are added and stirred, a natural antimicrobial agent and nitrogen or carbon dioxide are injected simultaneously to form a final mixture; The final mixture is dehydrated and placed in a mold for forming.

4. The method for preparing a degradable bio-based pressure-sensitive adhesive according to claim 3, wherein: The pretreatment comprises the following steps: The polylactic acid is placed in a drying oven and dried at 40° C.-60° C. for 1 to 2 hours.

5. The method for preparing the degradable bio-based pressure-sensitive adhesive according to claim 3, characterized in that: When the high-temperature mixer melt-mixes the polylactic acid and sodium alginate, the temperature is 160° C.-180° C. and the stirring time is 30 minutes to 60 minutes.

6. The method for preparing the degradable bio-based pressure-sensitive adhesive according to claim 3, characterized in that: When the camphor oil and glycerin are gradually added to the preliminary solution, the temperature remains unchanged and the solution is stirred for 10 to 20 minutes.

7. The method for preparing the degradable bio-based pressure-sensitive adhesive according to claim 3, characterized in that: After cooling in the high-temperature mixer, the temperature is not higher than 140° C., and when stirring is continued, the temperature is raised to -160° C. to 180° C. and stirred for 15 minutes to 30 minutes.

8. The method for preparing a degradable bio-based pressure-sensitive adhesive according to claim 3, characterized in that: When the natural antibacterial agent and nitrogen or carbon dioxide are injected simultaneously, stirring is continued for 5 to 10 minutes, and the nitrogen or carbon dioxide injection rate is 0.1-1.0 L / min and is continued for 5 to 10 minutes.

9. The method for preparing a degradable bio-based pressure-sensitive adhesive according to claim 3, characterized in that: The dehydration process comprises the following steps: The final mixture was transferred to a ventilated drying oven and dried at 45-60°C for 2 hours for preliminary dehydration; After initial dehydration, add 1% to 5% of solvent-free additives and stir evenly; Then place it in a vacuum drying oven at a temperature of 30-50°C and dry it for 4-8 hours.

10. A biodegradable bio-based pressure-sensitive adhesive environmentally friendly tape product, prepared by the preparation method of the biodegradable bio-based pressure-sensitive adhesive according to any one of claims 3 to 9, characterized in that: The pressure-sensitive adhesive is coated on a bio-based backing material to form a single-sided or double-sided pressure-sensitive adhesive tape.

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