Biodegradable resin type pressure-sensitive adhesive

Abstract

The invention discloses a biodegradable resin type pressure-sensitive adhesive which is prepared by carrying out an initiator-mediated polymerization reaction on lipoic acid and a monomer containing a carbon-carbon double bond in an organic solvent. The invention also discloses a preparation method. According to the resin type pressure-sensitive adhesive provided by the invention, the biodegradation period of the resin type pressure-sensitive adhesive can be effectively regulated and controlled, and the development of environment-friendly and organism-friendly (environment-friendly and medical) pressure-sensitive adhesives is facilitated.

Description

Technical Field

[0001] The invention relates to a biodegradable resin type pressure-sensitive adhesive, belonging to the technical field of degradable materials. Background Art

[0002] Pressure-sensitive adhesives (PSA) are primarily classified into resin and elastomer types based on their chemical composition and structure. Acrylates are a prime example of the former, and they are widely used in industries such as labeling, healthcare, automotive, display, and electronics. However, resin-based PSAs, such as those represented by acrylates, have an all-carbon backbone, making them difficult to degrade. In the display industry, acrylate PSAs are crucial for bonding and protecting the multiple, thin functional layers of display screens. However, removal often leaves residue, requiring treatment with dispersants or strong alkalis and mechanical scrubbing. This is costly, involves a complex chemical process, and can also scratch the functional layers. In the medical field, medical PSAs are commonly used in medical devices, medical dressings, and other medical products. In recent years, acrylate PSAs have gradually replaced traditional natural rubber-based PSAs. Because natural rubber ages easily, it is often dissolved by fat secreted by the human body and its internal organs after application, leading to penetration of the PSA into the body, skin allergies, and decreased adhesion.

[0003] Traditional pressure-sensitive adhesives are non-biodegradable, and their large-scale use has caused certain environmental pressures. In recent years, the research and development of biodegradable (according to the international standard ISO14855-1) pressure-sensitive adhesives has become a hot topic in scientific research and industry. Chinese invention patent CN115181528A discloses a biodegradable bio-based pressure-sensitive adhesive and its preparation method, which uses palm oil as the main material of biomass pressure-sensitive adhesive and uses ozone molecules as dipoles to react with organic matter. It will first react with the unsaturated bonds in the organic matter to oxidize the structure of palmitic acid triglyceride, and then use potassium borohydride with reducing properties to reduce it to generate palm oil-based polyols; Chinese invention patent CN118931437A discloses a high-viscosity / degradable acrylate pressure-sensitive adhesive and its preparation method, which is made of prop-2-ene-1 -aminocarbamate, 4-methyl-1,2-dithiolane-4-carboxylic acid, 3-methoxyacrylic acid, isobutyl cinnamate, docosyl methacrylate, a thermal initiator, and a solvent, and can maintain viscosity for a long time; Chinese invention patent CN115725058A discloses a preparation method of a degradable and recyclable copolyester and its application in pressure-sensitive adhesives, and utilizes the ring-opening copolymerization of δ-caprolactone and trans-hexahydro-(4,5)-benzofuranone to prepare a bio-based degradable copolyester, which can be used in pressure-sensitive adhesives and can be completely degraded under natural conditions without the need for additional tackifiers, plasticizers, and other additives.

[0004] Chinese invention patent CN119391306A discloses a degradable acrylic pressure-sensitive adhesive and its preparation method. The raw materials include polylactic acid, butyl acrylate, isooctyl acrylate, benzoyl peroxide, ethyl acetate, temperature-sensitive microcapsules, a tackifier, an antioxidant, and a stabilizer. The addition of the latter four components further improves the performance and degradability of the pressure-sensitive adhesive. Chinese invention patent CN115926692A discloses a degradable water-based acrylic pressure-sensitive adhesive, a degradable adhesive tape, and a preparation method. The degradable oligomer monomer is ε-caprolactone-modified hydroxyethyl methacrylate monomer and / or hydroxy-terminated polylactide modified with isocyanate to form a hydroxyethyl methacrylate monomer. The resulting water-based acrylic pressure-sensitive adhesive is degradable. Chinese invention patent CN119955460A discloses a fully biodegradable polycarbonate-based polyurethane hot-melt pressure-sensitive adhesive and its preparation method. By regulating the soft and hard segment structure and polar group content of the polyurethane, precise control of viscoelasticity, glass transition temperature and bonding properties can be achieved. The polyurethane hot-melt pressure-sensitive adhesive uses carbon dioxide-based polycarbonate diol as raw material. Summary of the Invention

[0005] The purpose of the present invention is to provide a biodegradable resin-type pressure-sensitive adhesive.

[0006] The technical solution adopted in the present invention is:

[0007] A biodegradable resin-type pressure-sensitive adhesive is prepared by polymerization of lipoic acid and a monomer containing a carbon-carbon double bond in an organic solvent mediated by an initiator.

[0008] Preferably, the monomer containing a carbon-carbon double bond is at least one of acrylic acid, methyl acrylate, methyl methacrylate, butyl acrylate, and isooctyl acrylate.

[0009] Preferably, the initiator is selected from azobisisobutyronitrile, potassium persulfate, ammonium persulfate, Fe 2+ -Select from hydrogen peroxide (Fenton system).

[0010] Preferably, the organic solvent is dichloromethane, chloroform, ethyl acetate, butyl acetate, toluene, or acetone.

[0011] The present invention also discloses a method for preparing the resin-based pressure-sensitive adhesive, which comprises the following steps:

[0012] A. Dissolve the monomer containing carbon-carbon double bonds in an organic solvent, add an initiator, stir evenly, and then heat to react for a period of time;

[0013] B. Add lipoic acid dropwise. Continue the reaction for a while after the addition is complete. Lipoic acid can be added dropwise through an addition funnel (or constant pressure funnel);

[0014] C. The reactants are precipitated in a mixed solution of at least one of methanol, ethanol, propanol, and isopropanol, or several thereof, to obtain a biodegradable resin-type pressure-sensitive adhesive.

[0015] Preferably, the monomer containing a carbon-carbon double bond accounts for 10 to 50 wt% of the total weight of the solution, the initiator accounts for 0.1 to 3% of the total weight of the solution, and the thioctic acid accounts for 1 to 35% of the total weight of the solution, wherein the solution refers to a solution in which the monomer containing a carbon-carbon double bond is dissolved in an organic solvent and the initiator and thioctic acid are added, and the balance is the organic solvent.

[0016] Preferably, in step A, after adding the monomer containing a carbon-carbon double bond into the organic solvent, the mixture is stirred at 20-50° C. for 0.1-1 h to dissolve the monomer containing a carbon-carbon double bond in the organic solvent.

[0017] Preferably, after adding the initiator in step A, the reaction system is heated to 60-90° C. and reacted for 0.5-3 h.

[0018] Preferably, the rate of adding lipoic acid in step B is 0.1-5 mL / min, and the reaction is continued for 0.5-10 h after the addition is completed. During and after the addition, the temperature of the reaction system is maintained at 60-90° C.

[0019] Preferably, the lipoic acid to be added dropwise is first dissolved in an organic solvent.

[0020] The biodegradation rate of the resin-type pressure-sensitive adhesive can be regulated by adjusting the feed ratio and the dripping speed of lipoic acid.

[0021] The resin-type pressure-sensitive adhesive provided by the present invention can effectively regulate its biodegradation cycle, and is helpful for the development of environmentally and organism-friendly (environmentally friendly and medical) pressure-sensitive adhesives. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The chemical reaction formula for the preparation process of biodegradable resin-type pressure-sensitive adhesive.

[0023] Figure 2 It is the chemical formula for the degradation of biodegradable resin-type pressure-sensitive adhesive.

[0024] Figure 3 This is a diagram of the preparation device for biodegradable resin-type pressure-sensitive adhesive.

[0025] Figure 4 Schematic diagram of biodegradable resin-type pressure-sensitive adhesive. Specific implementation methods

[0026] The present invention will be further described below with reference to the examples, but the description of the examples does not limit the scope of protection of the present invention in any way.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention pertains. The terms used in the specification of the present invention are intended only to describe specific embodiments and are not intended to limit the present invention. Furthermore, while examples of parameters including specific values may be provided herein, it should be understood that the parameters do not need to be exactly equal to the corresponding values, but may be approximated to the corresponding values within acceptable error tolerances or design constraints.

[0028] Unless otherwise specified, the materials and instruments used in the following examples can be obtained from conventional commercial channels.

[0029] Example 1: Take 100 mL of butyl acetate, add 5 g of methyl acrylate, 10 g of butyl acrylate and 1 g of azobisisobutyronitrile, stir at 25 ° C, 400 rpm for 0.5 h. After fully dissolved, heat to 70 ° C and react for 0.5 h, then Figure 3 2 g of lipoic acid (dissolved in 10 mL of butyl acetate) was added dropwise to the apparatus at a rate of 2.5 mL / min. The reaction was continued at 70°C for 5 h. After cooling to room temperature, the resulting polymer was precipitated in a mixed solvent of methanol and ethanol in a volume ratio of 1:1. The precipitated product was collected by centrifugation at 4000 rpm for 5 min, and the organic solvent was removed by evaporation for 24 h to obtain pressure-sensitive adhesive product 1, as shown in the reaction formula. Figure 1 Its characteristic is that it can be slowly degraded in the natural environment. The degradation reaction is as follows Figure 2 The degradation process is shown in Figure 4 shown.

[0030] Example 2: Take 100 mL of butyl acetate, add 5 g of methyl acrylate, 10 g of butyl acrylate and 1 g of azobisisobutyronitrile, stir at 25 ° C, 400 rpm for 0.5 h. After fully dissolved, heat to 70 ° C and react for 0.5 h, then Figure 3 1.5 g of lipoic acid (dissolved in 10 mL of butyl acetate) was added dropwise to the apparatus at a rate of 2.5 mL / min. The reaction was continued at 70°C for 5 hours. After cooling to room temperature, the resulting polymer was precipitated in a mixed solvent of methanol:ethanol (1:1 by volume). The precipitated product was collected by centrifugation at 4000 rpm for 5 minutes and evaporated for 24 hours to remove the organic solvent, yielding pressure-sensitive adhesive product 2.

[0031] Example 3: Take 100 mL of butyl acetate, add 5 g of methyl acrylate, 10 g of butyl acrylate and 1 g of azobisisobutyronitrile, stir at 25 ° C, 400 rpm for 0.5 h. After fully dissolved, heat to 70 ° C and react for 0.5 h, then Figure 31.5 g of lipoic acid (dissolved in 10 mL of butyl acetate) was added dropwise to the apparatus at a rate of 2.0 mL / min. The reaction was continued at 70°C for 5 h. After cooling to room temperature, the resulting polymer was precipitated in a mixed solvent of methanol:ethanol (1:1 by volume). The precipitated product was collected by centrifugation at 4000 rpm for 5 min and evaporated for 24 h to remove the organic solvent, yielding pressure-sensitive adhesive product 3.

[0032] Table 1. Comparison of product performance obtained in various examples

[0033] Products in each embodiment Peel strength 1 Peel strength after 14 days of degradation 14-day degradation rate 3 Example 1 19.2N / mm 13.5N / mm 36.2％ Example 2 20.9N / mm 14.7N / mm 47.9％ Example 3 21.3N / mm 16.2N / mm 50.8％

[0034] Note 1: Peel strength is based on GB / T 2792-2014;

[0035] Note 2: The degradation method is to completely immerse the sample in municipal tap water exposed to air;

[0036] Note 3: Degradation rate = (initial sample mass - degraded sample mass) / initial sample mass × 100%

[0037] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A biodegradable resin-type pressure-sensitive adhesive, characterized in that: It is formed by the polymerization reaction of lipoic acid and monomers containing carbon-carbon double bonds in an organic solvent mediated by an initiator.

2. The resin-based pressure-sensitive adhesive according to claim 1, characterized in that: The monomer containing a carbon-carbon double bond is at least one of acrylic acid, methyl acrylate, methyl methacrylate, butyl acrylate, and isooctyl acrylate.

3. The resin-based pressure-sensitive adhesive according to claim 1 or 2, characterized in that: The initiator is selected from azobisisobutyronitrile, potassium persulfate, ammonium persulfate, Fe 2+ -Select from hydrogen peroxide.

4. The resin-based pressure-sensitive adhesive according to claim 3, characterized in that: The organic solvent is one or a mixture of dichloromethane, chloroform, ethyl acetate, butyl acetate, toluene and acetone.

5. The method for preparing the resin-based pressure-sensitive adhesive according to any one of claims 1 to 4, characterized in that: The steps include: A. Dissolve the monomer containing carbon-carbon double bonds in an organic solvent, add an initiator, stir evenly, and then heat to react for a period of time; B. Add lipoic acid dropwise and continue the reaction for a while after the addition is complete; C. The reactants are precipitated in a mixed solution of at least one of methanol, ethanol, propanol, and isopropanol, or several thereof, to obtain a biodegradable resin-type pressure-sensitive adhesive.

6. The preparation method according to claim 5, characterized in that The monomer containing a carbon-carbon double bond accounts for 10-50wt% of the total weight of the solution, the initiator accounts for 0.1-3% of the total weight of the solution, and the thioctic acid accounts for 1-35% of the total weight of the solution. The solution refers to a solution in which the monomer containing a carbon-carbon double bond is dissolved in an organic solvent and the initiator and thioctic acid are added, and the balance is the organic solvent.

7. The preparation method according to claim 6, characterized in that In step A, after adding the monomer containing a carbon-carbon double bond into the organic solvent, the mixture is stirred at 20-50° C. for 0.1-1 h to dissolve the monomer containing a carbon-carbon double bond in the organic solvent.

8. The preparation method according to claim 7, characterized in that After adding the initiator in step A, the reaction system is heated to 60-90° C. and reacted for 0.5-3 h.

9. The preparation method according to claim 8, characterized in that In step B, the rate of adding lipoic acid is 0.1-5 mL / min. After the addition is completed, the reaction is continued for 0.5-10 h. During and after the addition, the temperature of the reaction system is maintained at 60-90° C.

10. The preparation method according to any one of claims 5 to 9, characterized in that: The added lipoic acid is first dissolved in an organic solvent.

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