Bio-based self-healing elastomer and preparation method and application of water-based pressure-sensitive adhesive of bio-based self-healing elastomer

Abstract

The invention discloses a preparation method of a bio-based self-healing material, which comprises the following steps: (1) dissolving polyethyleneimine in deionized water, and stirring until the polyethyleneimine is completely dissolved to obtain a polyethyleneimine aqueous solution; (2) dispersing water-soluble starch in deionized water, heating in a water bath, and stirring until the solution is transparent to obtain a starch aqueous solution; (3) mixing the polyethyleneimine aqueous solution obtained in the step (1) and the starch aqueous solution obtained in the step (2) according to a mass ratio of 1: (0.1-10), and uniformly stirring; (4) carrying out reduced pressure distillation on the mixed solution to remove excessive moisture, so as to obtain a solid product; and (5) putting the solid product into a mold containing a release agent, pressurizing, heating and forming to obtain the self-healing elastomer material. The material has excellent self-healing performance, and the aqueous solution of the material can be directly used as a water-based pressure-sensitive adhesive, and has the characteristics of good adhesion, easy washing, biodegradability and the like.

Description

Technical Field

[0001] The present invention relates to the preparation and application fields of self-healing materials, and in particular to a simple preparation method of a hydrogen-bond cross-linked bio-based self-healing material and its application in the field of water-based pressure-sensitive adhesives. Background Art

[0002] With society's increasing emphasis on sustainable development and environmental protection, bio-based materials are attracting widespread attention due to their renewable and biodegradable properties. Self-healing materials, as a class of intelligent materials capable of self-repairing after damage, offer significant advantages in extending material lifespan, improving safety, and reducing maintenance costs. While research on bio-based self-healing materials has become a hot topic in recent years, their complex preparation methods and high costs have limited their widespread adoption in practical applications.

[0003] Pressure-sensitive adhesives (PSA) are adhesives that bond with minimal pressure and are widely used in packaging, medical, electronics, and other fields. Traditional PSAs are often made from synthetic polymers, which can lead to environmental pollution and resource depletion. In recent years, water-based PSAs have garnered attention for their low VOC (volatile organic compound) emissions and ease of cleaning, but their performance and application scope still need to be expanded.

[0004] Existing technologies typically use chemical crosslinking and nanocompositing methods to prepare bio-based self-healing materials. These processes are complex and costly, making large-scale production difficult. Furthermore, existing water-based pressure-sensitive adhesives (PSAs) are mostly based on acrylic emulsions, which have poor biodegradability and lag behind traditional PSA in terms of adhesion and durability.

[0005] Therefore, the present invention aims to provide a simple preparation method to prepare a bio-based material with self-healing properties, and apply it to the field of water-based pressure-sensitive adhesives to solve the problems of complex preparation process, high cost and environmental pollution in the existing technology. Summary of the Invention

[0006] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a method for preparing a bio-based self-healing material and its application as a water-based pressure-sensitive adhesive. The present invention prepares an elastomeric material with self-healing properties by blending an aqueous solution of polyethyleneimine (PEI) with an aqueous solution of water-soluble starch, casting and removing the water. This material not only exhibits excellent self-healing properties, but its aqueous solution can also be directly used as a water-based pressure-sensitive adhesive, exhibiting good adhesion, easy water washing, and biodegradability.

[0007] A method for preparing a bio-based self-healing material comprises the following steps:

[0008] (1) dissolving polyethyleneimine in deionized water and stirring until completely dissolved to obtain a polyethyleneimine aqueous solution;

[0009] (2) dispersing water-soluble starch in deionized water, heating in a water bath and stirring until the solution is transparent to obtain a starch aqueous solution;

[0010] (3) mixing the polyethyleneimine aqueous solution of step (1) and the starch aqueous solution of step (2) in a mass ratio of 1:0.1-10 and stirring uniformly;

[0011] (4) performing reduced pressure distillation on the mixed solution to remove excess water to obtain a solid product;

[0012] (5) placing the solid product in a mold containing a release agent, pressing and heating the mold to obtain a self-healing elastomer material.

[0013] Furthermore, in step (1), the molecular weight of polyethyleneimine is 600,000-800,000 g / mol, and the mass ratio of polyethyleneimine to deionized water is 1:1-10; in step (2), the mass ratio of starch to deionized water is 1:10-100, and the water bath temperature is 60-90° C.; in step (5), the heating temperature of the mold is 80-110° C., the pressurization pressure is 0.1-5 MPa, and the molding time is 12-72 h.

[0014] Furthermore, in step (3), the mass ratio of the polyethyleneimine aqueous solution to the starch aqueous solution is 1:0.5-5.

[0015] Furthermore, the temperature of the reduced pressure distillation in step (4) is 50-80° C., and the time is 60-180 min.

[0016] Furthermore, the release agent in step (5) is dodecafluoroheptylpropyltrimethoxysilane.

[0017] Furthermore, a bio-based self-healing elastomeric material prepared by the above method is provided, which has a tensile strength of 5-10 MPa, an elongation at break of 100-150%, and a self-healing efficiency of ≥80% within 24 hours at room temperature.

[0018] Furthermore, a method for preparing a water-based pressure-sensitive adhesive is provided, comprising: mixing the elastomeric material according to claim 6 with deionized water in a mass ratio of 1:10-50, heating to 60-90°C, stirring and dissolving, and evaporating to adjust the solid content to 40-60% to obtain a pressure-sensitive adhesive solution; coating the pressure-sensitive adhesive solution on a substrate, drying at 50-80°C for 10-60 minutes, and forming a pressure-sensitive adhesive film with a thickness of 20-100 μm.

[0019] Furthermore, the substrate is a PVC film, a polyester film or a paper material, and the 180° peel strength of the pressure-sensitive adhesive film is ≥7N / 25mm, and the holding force is ≥35h.

[0020] Furthermore, a water-based pressure-sensitive adhesive prepared by the above method is provided, wherein the pressure-sensitive adhesive film has an initial adhesion of 15-25# (GB / T 4852-2002), a lasting adhesion of ≥30h (GB / T 4851-2014), and a peel strength of 5-10N / 25mm (GB / T2792-2014).

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The preparation method of the self-healing elastomeric material of the present invention is simplified. By physically blending PEI and a starch aqueous solution, combined with vacuum distillation and heated pressure molding, complex processes such as chemical crosslinking and nanocomposite are avoided, and the production cost is reduced by more than 50%. By optimizing the PEI molecular weight and the ratio of PEI to water, the ratio of starch to water, the temperature and the process parameters of subsequent demolding, it is ensured that the polymer chains form a dense hydrogen bond network; promote the uniform dispersion of starch microcrystals, avoid agglomeration, and enhance the physical crosslinking effect. , Eliminate bubble defects, and obtain an elastomeric material with uniform thickness and smooth surface. The prepared elastomeric material also has excellent tensile strength, elongation at break, and excellent self-healing properties due to the synergistic enhancement of the PEI hydrogen bond network and starch microcrystals. Its aqueous solution can also be directly used as a water-based pressure-sensitive adhesive, with good adhesion, easy water washing, and biodegradability.

[0023] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0025] Figure 1 The transparent elastomer material obtained in Example 1;

[0026] Figure 2 This is an atomic force microscope image of Example 1;

[0027] Figure 3 The XRD results of Example 1 and Comparative Example 1 are shown below:

[0028] Figure 4 This is a photo of the fracture in the bent state after healing in Example 3;

[0029] Figure 5 2 are stress-strain curves of Example 2 and Example 3;

[0030] Figure 6This is a photo of Example 5 after one month of degradation. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0032] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0033] Example 1: Preparation of self-healing elastomeric material

[0034] 1) Dissolve 10 g of PEI (700,000 g / mol) in 90 g of deionized water and stir until completely dissolved to obtain 100 g of a 10% (w / w) PEI aqueous solution.

[0035] 2) 10 g of water-soluble starch was dispersed in 190 g of deionized water and thoroughly stirred at 80° C. until the solution became almost transparent, to obtain 200 g of a 5% (w / w) starch aqueous solution.

[0036] 3) The product prepared in step 1) and the product prepared in step 2) were mixed in a mass ratio of 1:2 and stirred evenly.

[0037] 4) The product prepared in step 3) is subjected to reduced pressure distillation to remove excess water from the mixed solution to obtain a solid product.

[0038] 5) The product prepared in step 4) was placed in a glass mold coated with a release agent, and pressed at 80° C. and 0.5 MPa for 48 hours to prepare a self-healing elastomer material with uniform thickness.

[0039] The transparent elastomer material obtained in Example 1 is shown in FIG. Figure 1 , it can be seen that the starch is evenly dispersed in the material without macroscopic phase separation

[0040] Example 2: Tensile properties test

[0041] 1) The self-healing elastomer material prepared in Example 1 was cut into strips of 80×15×2 mm.

[0042] 2) The sample prepared in 1) was subjected to a tensile test at a test speed of 300 mm / min. The tensile strength was 7.8 MPa and the elongation at break was 132%.

[0043] The atomic force microscope image of Example 1 is shown in Figure 2, it can be seen that PEI and starch form a nano-microphase structure after simple compounding.

[0044] Example 3: Self-healing performance test

[0045] 1) The self-healing elastomer material prepared in Example 1 was cut into 80×15×2 mm strips, and the strips were cut into two sections in the middle.

[0046] 2) Align the fracture surfaces of the two sections of material and press them gently to make them contact. Place them at room temperature (23°C) for 24 hours and observe the fracture healing. Figure 4 .

[0047] 3) The healed material was subjected to a tensile test at a test speed of 300 mm / min. The tensile strength was 6.3 MPa, the elongation at break was 118%, and the ratio of the tensile strength of Example 3 to that of Example 2 was used as the healing degree, which was 80.7%.

[0048] The stress-strain curves of Example 2 and Example 3 are shown in Figure 5 .

[0049] Example 4: Performance test of water-based pressure-sensitive adhesive

[0050] 5 g of the sample prepared in Example 1 was added to 100 ml of deionized water and thoroughly stirred at 80°C to dissolve. The solution was then heated at 80°C for 2 h to evaporate the bulk of the water, yielding a viscous adhesive solution with a solids content of 52%. The solution was evenly coated onto a PVC film using a spatula to a coating thickness of 50 μm. The coated PVC film was then dried in a 60°C oven for 30 min to form a pressure-sensitive adhesive film.

[0051] The initial adhesion, lasting adhesion and peeling strength tests of the pressure-sensitive adhesive film were carried out.

[0052] Initial adhesion test: According to GB / T 4852-2002 standard, using the rolling ball method, the test result is 22#.

[0053] Adhesion test: According to GB / T 4851-2014, the film was attached to a stainless steel plate, a weight was attached, and the film peeling time was recorded as 36 hours.

[0054] Peel strength test: According to GB / T 2792-2014 standard, 180° peeling, test speed 300mm / min, peel strength is 7.7N / 25mm.

[0055] Adhesive removal test: After soaking the PVC film in deionized water for one week, the pressure-sensitive adhesive on the PVC completely fell off.

[0056] Example 5: Biodegradability Test

[0057] The self-healing elastomer material prepared in Example 1 was cut into small pieces of 10×10×3 mm.

[0058] The material blocks were immersed in deionized water and placed in an environment at room temperature of 25°C and humidity of 60%. The degradation was observed. Mold began to appear in the sample within a week and continued to degrade. After a month, no solid residue remained. Figure 6 This is a photo taken one month after degradation. You can see that there is no solid residue.

[0059] Comparative Example 1:

[0060] 50g of starch was dispersed in 250ml of deionized water, heated to 80°C and stirred thoroughly to dissolve, then poured into a polytetrafluoroethylene mold and dried at 80°C to obtain a pure starch film without the addition of PEI. This material was inelastic, brittle and extremely fragile, making it impossible to perform mechanical property tests.

[0061] Comparative Example 2:

[0062] 2g of PEI was placed in a glass mold coated with a release agent and pressed at 80°C and 0.5MPa for 48h. The results showed that PEI without starch was a viscous polymer and could not be molded into a material.

[0063] The XRD results of Example 1 and Comparative Example 1 are shown in Figure 3 The XRD results of Example 1 and Comparative Example 1 are multi-peaked, while that of Example 1 is single-peaked, indicating that the starch in Example 1 interacts with PEI to change the starch crystal structure. The formed nanocomposite structure provides physical crosslinking for Example 1, thereby enhancing its mechanical properties compared with Comparative Examples 1-2.

[0064] Throughout this specification, terms such as "one embodiment" or "some embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present application. In this specification, schematic representations 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 any one or more embodiments or examples.

[0065] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a bio-based self-healing material, characterized in that: The following steps are involved: (1) dissolving polyethyleneimine in deionized water and stirring until completely dissolved to obtain a polyethyleneimine aqueous solution; (2) dispersing water-soluble starch in deionized water, heating in a water bath and stirring until the solution is transparent to obtain a starch aqueous solution; (3) mixing the polyethyleneimine aqueous solution of step (1) and the starch aqueous solution of step (2) in a mass ratio of 1:0.1-10 and stirring uniformly; (4) performing reduced pressure distillation on the mixed solution to remove excess water to obtain a solid product; (5) placing the solid product in a mold containing a release agent, pressing and heating the mold to obtain a self-healing elastomer material.

2. The preparation method according to claim 1, wherein In step (1), the molecular weight of polyethyleneimine is 600,000-800,000 g / mol, and the mass ratio of polyethyleneimine to deionized water is 1:1-10; in step (2), the mass ratio of starch to deionized water is 1:10-100, and the water bath temperature is 60-90° C.; in step (5), the heating temperature of the mold is 80-110° C., the pressurizing pressure is 0.1-5 MPa, and the molding time is 12-72 h.

3. The preparation method according to claim 1, characterized in that In the step (3), the mass ratio of the polyethyleneimine aqueous solution to the starch aqueous solution is 1:0.5-5.

4. The preparation method according to claim 1, characterized in that The temperature of the reduced pressure distillation in step (4) is 50-80° C. and the time is 60-180 min.

5. The preparation method according to claim 1, characterized in that The release agent in step (5) is dodecafluoroheptylpropyltrimethoxysilane.

6. A bio-based self-healing elastomer material prepared by the method according to any one of claims 1 to 5, characterized in that: Its tensile strength is 5-10MPa, its elongation at break is 100-150%, and its self-healing efficiency at room temperature for 24 hours is ≥80%.

7. A method for preparing a water-based pressure-sensitive adhesive, characterized in that: include: The elastomeric material according to claim 6 is mixed with deionized water in a mass ratio of 1:10-50, heated to 60-90°C and stirred to dissolve, and evaporated to adjust the solid content to 40-60% to obtain a pressure-sensitive adhesive solution; the pressure-sensitive adhesive solution is coated on a substrate and dried at 50-80°C for 10-60 minutes to form a pressure-sensitive adhesive film with a thickness of 20-100 μm.

8. The method for preparing a water-based pressure-sensitive adhesive according to claim 7, wherein: The substrate is a PVC film, a polyester film or a paper material; the 180° peeling strength of the pressure-sensitive adhesive film is ≥7N / 25mm, and the holding force is ≥35h.

9. A water-based pressure-sensitive adhesive prepared by the method according to any one of claims 7 to 8, characterized in that: The initial tack of the pressure-sensitive adhesive film is 15-25# using the rolling ball method according to GB / T 4852-2002. The holding strength is tested by attaching the film to a stainless steel plate and hanging a weight on it for more than 30 hours according to GB / T 4851-2014. The peel strength is 5-10N / 25mm after 180° peeling at a test speed of 300mm / min according to GB / T 2792-2014.

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