A high-bio-carbon-content bio-based waterborne pressure-sensitive adhesive and a preparation method thereof

Abstract

The application provides a high-bio-carbon-content bio-based water-based pressure-sensitive adhesive and a preparation method thereof.The high-bio-carbon-content bio-based water-based pressure-sensitive adhesive is prepared from raw materials, and the raw materials comprise the following components in parts by weight: 280-380 parts of deionized water, 1-3 parts of sodium bicarbonate, 25-35 parts of alkyl sulfate anionic surfactant A and polyoxyethylene ether nonionic surfactant B in total, 180-280 parts of soft monomer S1, 200-300 parts of hard monomer S2, 5-12 parts of functional monomer, 5-12 parts of persulfate initiator and 5-12 parts of aziridine crosslinking agent.Compared with traditional petroleum-based pressure-sensitive adhesive and solvent-based pressure-sensitive adhesive, the application is more green and environmentally friendly, does not need to use organic solvents, reduces safety hazards, and is more in line with the demand for sustainable development.

Description

Technical Field

[0001] This invention relates to the field of pressure-sensitive adhesive technology, specifically to a bio-based water-based pressure-sensitive adhesive with high biocarbon content and its preparation method. Background Technology

[0002] Most commercial pressure-sensitive adhesives use raw materials derived from petroleum or fossil resources. However, with the increasing demand for sustainable development, bio-based pressure-sensitive adhesives that use natural renewable resources as raw materials are gradually attracting the attention of researchers in the industry.

[0003] Solvent-based pressure-sensitive adhesives require large amounts of organic solvents, such as ethyl acetate, during production, leading to severe environmental pollution and resource waste. Environmentally friendly water-based adhesives, which replace organic solvents with water, have become a major development trend in the adhesive industry.

[0004] In existing technologies, plant oils such as epoxidized soybean oil or palm oil are typically used as renewable resource raw materials to prepare pressure-sensitive adhesives, as disclosed in CN114958300A, which describes a method for preparing bio-based pressure-sensitive adhesives. However, this method still requires the use of large amounts of organic solvents, which is not conducive to sustainable development. Summary of the Invention

[0005] Commercially available pressure-sensitive adhesives are mainly petroleum-based solvent-based, which is not conducive to sustainable development. The purpose of this invention is to solve the above problems by providing a high-biocarbon-content bio-based water-based pressure-sensitive adhesive and its preparation method. The water-based pressure-sensitive adhesive provided by this invention has a high biocarbon content, and the preparation process does not require the use of organic solvents. The final product exhibits good adhesion to various substrates and leaves minimal residue after removal.

[0006] The present invention adopts the following technical solution: A method for preparing a bio-based water-based pressure-sensitive adhesive with high biochar content: By weight, the main raw materials include the following: 280-380 parts deionized water, 1-3 parts sodium bicarbonate, 25-35 parts emulsifier, 180-280 parts soft monomer S1, 200-300 parts hard monomer S2, 5-12 parts functional monomer, 5-12 parts persulfate initiator and 5-12 parts aziridine crosslinking agent.

[0007] The soft monomer S1 is at least one of n-butyl acrylate and 2-ethylhexyl acrylate.

[0008] Preferably, the hard monomer S2 is derived from a class of unsaturated acids F containing four carbon atoms. Unsaturated acid F can be produced by fermentation of lignocellulosic bundles, and it can undergo esterification with biobutanol under concentrated sulfuric acid catalysis to obtain hard monomer S2. For example, the hard monomer S2 is dibutyl fumarate; The functional monomer is at least one of acrylic acid and 4-hydroxybutyl acrylate; the emulsifier is an alkyl sulfate anionic surfactant A and a polyoxyethylene ether nonionic surfactant B; the aziridine crosslinking agent is trimethylolpropane-tris[3-(2-methylaziridine)propionate].

[0009] The alkyl sulfate anionic surfactant A is sodium dodecyl sulfate; the polyoxyethylene ether nonionic surfactant B is OP-10; and the persulfate initiator is potassium persulfate.

[0010] Furthermore, the method includes the following steps: (a) Preparation of monomer preemulsion: Weigh deionized water and emulsifier, add them to an emulsification kettle and stir at high speed. Then, slowly add the soft monomers, hard monomers and functional monomers sequentially (at a speed of 4-6 ml / min), and stir until homogeneous to obtain the monomer preemulsion. Preferably, in the monomer preemulsion, the mass ratio of soft monomers to hard monomers is in the range of 1:1-1.7 (e.g., 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.7). Preferably, in the monomer preemulsion, the mass percentage of the functional monomer ranges from 2-4 wt% of the total mass of the three monomers (e.g., 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, or 4 wt%). Preferably, the mass percentage of deionized water in the monomer preemulsion is 20-40 wt% (e.g., 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%).

[0011] (b) Weigh deionized water and emulsifier, add them to the reactor and stir and heat to 70-85°C. Add 3-6 wt% of the total monomer pre-emulsion to the reactor, add some initiator and deionized water (at a rate of 0.7-1.1 ml / min), and polymerize for 25-35 minutes.

[0012] Preferably, the mass ratio of deionized water and emulsifier added to the reactor is in the range of 28-45:1 (e.g., 28:1, 30:1, 35:1, 40:1 or 45:1). Preferably, the initiator added to the reactor is 30% to 70% of the total mass of the initiator (e.g., 30%, 35 wt%, 40 wt%, 50 wt%, 60 wt%, or 70 wt%). Preferably, the mass ratio of initiator to emulsifier is 0.2 to 0.8:1 (e.g., 0.2:1, 0.3:1, 0.5:1, 0.7:1 or 0.8:1). (c) The remaining monomer pre-emulsion (at a rate of 0.7-1.1 ml / min) and initiator solution (at a rate of 0.05-0.08 ml / min) are slowly added dropwise to the reactor over 3-4 hours.

[0013] (d) After the reaction is complete, adjust the pH and viscosity, add aziridine crosslinking agent to the emulsion, coat and dry to make water-based pressure-sensitive adhesive.

[0014] As a preferred embodiment of the present invention, the mass percentage of deionized water in the monomer preemulsion is 20-35 wt%, more preferably 23-27 wt%.

[0015] During the monomer pre-emulsification process, the stirring speed is preferably 200-1000 rpm, more preferably 500-1000 rpm.

[0016] In the monomer preemulsion, the monomers should be added slowly in order of increasing polarity.

[0017] In the monomer preemulsion, the total amount of the two emulsifiers is preferably 2.5-5 wt% of the monomer, more preferably 4.5-4.8 wt%.

[0018] During the monomer pre-emulsification process, the preferred emulsification temperature is 25-50℃, and more preferably 35-50℃.

[0019] During the monomer pre-emulsification process, the preferred emulsification time is 30 min-120 min, and more preferably 60-90 min.

[0020] The deionized water added to the reactor is preferably 25-40 wt% of the monomer, more preferably 30-35 wt%.

[0021] The total amount of the two emulsifiers added to the reactor is preferably 1-1.5 wt% of the monomer, more preferably 1.1-1.3 wt%.

[0022] The preferred ratio of the two emulsifiers is anionic surfactant: nonionic surfactant 1:3, more preferably anionic surfactant: nonionic surfactant 1:2.

[0023] In step (b), the mass fraction of the monomer preemulsion added first is preferably 3-10 wt%, more preferably 3-5 wt%.

[0024] In step (b), the temperature required for the reaction depends on the type of thermal initiator.

[0025] In step (b), the reaction time is preferably 15-35 minutes, and the emulsion is ensured to turn blue.

[0026] In step (b), the particle size of the obtained polymer emulsion is preferably 50-200 nanometers, more preferably 50-100 nanometers.

[0027] In step (b), the added initiator is preferably 30-45 wt% of the total initiator amount, more preferably 30-35 wt% of the total initiator amount.

[0028] To produce pressure-sensitive adhesive tape from the pressure-sensitive adhesive emulsion, the following steps are required: (1) Adjust the pH value to about 7 with ammonia water after discharging from the reactor.

[0029] (2) Remove a small amount of gel by vacuum filtration.

[0030] (3) Add small molecule crosslinking agent and stir thoroughly.

[0031] (4) Coat on release film or substrate, dry excess moisture in a blower oven and cover with release film for protection.

[0032] Advantages and positive effects: The bio-based waterborne pressure-sensitive adhesive of this invention is more environmentally friendly than traditional petroleum-based and solvent-based pressure-sensitive adhesives. It does not require the use of organic solvents, which reduces safety hazards and is more in line with the needs of sustainable development. Attached Figure Description

[0033] Figure 1. Schematic diagram of the synthesis path; Figure 2. Infrared image of emulsion demulsification and precipitation in Example 1; Figure 3. Distribution of emulsion particle size. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of the invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, the invention adopts the following technical solution: A method for preparing a bio-based water-based pressure-sensitive adhesive with high biocarbon content includes the following steps; (a) Preparation of monomer preemulsion: Weigh deionized water and emulsifier, add them to the emulsification kettle and stir at high speed. Then slowly add soft monomer, hard monomer and functional monomer in sequence, and stir evenly at 600 rpm to obtain monomer preemulsion.

[0035] (b) Weigh out deionized water and emulsifier, add them to the reactor and stir and heat to 70-85°C. Add 3-6 wt% of the total amount of monomer pre-emulsion to the reactor, add some initiator, and polymerize for 25-35 minutes.

[0036] (c) The remaining monomer pre-emulsion and initiator solution are slowly added dropwise to the reactor over 3-4 hours.

[0037] (d) After the reaction is complete, keep warm for 30-90 minutes, adjust the pH value and viscosity, and then coat and dry to make water-based pressure-sensitive adhesive.

[0038] Unless otherwise stated, all equipment used in the embodiments and comparative examples is commercially available. Specifically, the experimental equipment required in the following embodiments and test examples is as follows: Rolling ball method initial tack tester (HP-CZY-G): Jinan Hengpin Electromechanical Technology Co., Ltd.; Room temperature tape holding power tester (HP-CZY-6S): Jinan Hengpin Electromechanical Technology Co., Ltd.; NKT6100-B laser particle size analyzer: Shandong Niket Analytical Instruments Co., Ltd.; Universal tensile testing machine; Laboratory coating machine. All raw materials or reagents not specifically mentioned in this invention are conventional materials in the art and can be purchased commercially.

[0039] Alkylphenol polyoxyethylene ether-10 (OP-10), supplier: Aladdin, item number: O304931.

[0040] Example 1: Preparation of Bio-based Aqueous Pressure-sensitive Latex Includes the following steps: Add 39.95 g of deionized water to a pre-emulsification vessel, followed by 3.81 g of alkylphenol polyoxyethylene ether-10 (OP-10) (supplier: Aladdin, item number: O304931) and 1.91 g of sodium dodecyl sulfate. Heat to 50°C and start mechanical stirring at 600 rpm. Then, add 45.74 g of n-butyl acrylate, 75.92 g of dibutyl fumarate, 2.55 g of acrylic acid, and 0.25 g of sodium bicarbonate in sequence at a rate of 6 ml / min. After pre-emulsification for 60 min, remove the monomer pre-emulsion for later use.

[0041] 42.75 g of deionized water, 0.95 g of alkylphenol polyoxyethylene ether-10, and 0.475 g of sodium dodecyl sulfate were added to the reactor. The temperature was raised to 70°C, and the stirring speed was set to 250 rpm. Then, 1.01 g of potassium persulfate initiator was dissolved in 20.37 g of deionized water and added to the reactor at a rate of 1.1 ml / min. Subsequently, 8.48 g of monomer pre-emulsion was added at once. After reacting for 30 min, the mixture was removed to obtain the seed emulsion for later use.

[0042] The seed emulsion should appear distinctly bluish-white in dim light.

[0043] Take out the prepared seed emulsion and add it to the reaction vessel. Heat it to 70°C and set the stirring speed to 250 rpm. Dissolve 0.61 g of potassium persulfate initiator in 13.15 g of deionized water. Use a peristaltic pump to slowly add the remaining monomer pre-emulsion (at a rate of 1.1 ml / min) and potassium persulfate aqueous solution (at a rate of 0.08 ml / min) to the reaction vessel over 4 h.

[0044] During the reaction, the emulsion gradually changed from bluish-white to milky white.

[0045] The final emulsion after the reaction was completed was removed, and the particle size distribution of the latex particles in the final emulsion was characterized using a laser particle size analyzer. The results are as follows: Figure 3 As shown.

[0046] After the reaction, the emulsion was adjusted to pH 7 with ammonia water and filtered through a wire mesh to remove the gel-like residue, resulting in an aqueous pressure-sensitive adhesive emulsion. 0.6 g of trimethylolpropane-tris[3-(2-methylacridinyl)propionate] was added to the emulsion as a crosslinking agent. The aqueous pressure-sensitive adhesive emulsion was then evenly coated onto the surface of a corona-treated release film (S75TA3, release force 5-8 gf / ml, 75 μm, Shenzhen Shunhexing Electronic Materials Co., Ltd.) using a coating rod. The corona treatment parameters were: plasma treatment time 180 seconds, treatment distance 5 cm, and plasma treatment voltage 30 volts.

[0047] The aqueous pressure-sensitive adhesive emulsion is milky white with a bluish tint. The emulsion is fine, with no obvious particulate gel residue, and has a minimal residual monomer odor.

[0048] Take approximately 2 g of the final emulsion and place it in an aluminum tray. Then, place the tray in a 120°C forced-air drying oven. Remove the tray and weigh it every 30 minutes until the weight remains constant. The solid content is the ratio of the remaining mass of the emulsion after drying to the mass of the emulsion sample.

[0049] The final emulsion solids content of Example 1 is approximately 50%.

[0050] The release film coated with emulsion is placed in a 60°C oven and cured for 30 minutes. The release film is then used to cover the adhesive layer to produce a water-based pressure-sensitive adhesive tape with an adhesive layer thickness of approximately 200µm.

[0051] Example 2 Preparation of bio-based waterborne pressure-sensitive adhesive latex Includes the following steps: Add 25.10 g of deionized water, 2.25 g of OP-10, and 1.13 g of sodium dodecyl sulfate to a pre-emulsification vessel. Heat to 50°C and start mechanical stirring at 600 rpm. Then, add 30.00 g of n-butyl acrylate, 45.90 g of dibutyl fumarate, 1.5 g of acrylic acid, and 0.15 g of sodium bicarbonate in sequence at a rate of 6 ml / min. After pre-emulsification for 60 min, remove the monomer pre-emulsion for later use.

[0052] Add 25.02 g of deionized water, 0.56 g of OP-10, and 0.28 g of sodium dodecyl sulfate to the reactor. Heat to 70°C and set the stirring speed to 250 rpm. Then, add 0.70 g of potassium persulfate initiator, soluble in 13.00 g of deionized water, to the reactor at a rate of 1.1 ml / min. Subsequently, add 3.00 g of monomer pre-emulsion all at once. After reacting for 30 min, remove the emulsion to obtain the seed emulsion for later use.

[0053] The seed emulsion should appear distinctly bluish-white in dim light.

[0054] Take out the prepared seed emulsion and add it to the reaction vessel. Heat it to 70°C and set the stirring speed to 250 rpm. Dissolve 0.35 g of potassium persulfate initiator in 7.5 g of deionized water. Use a peristaltic pump to slowly add the remaining monomer pre-emulsion (at a rate of 1.1 ml / min) and potassium persulfate aqueous solution (at a rate of 0.08 ml / min) to the reaction vessel over 4 h.

[0055] During the reaction, the emulsion gradually changed from bluish-white to milky white.

[0056] The final emulsion after the reaction was completed was removed, and the particle size distribution of the latex particles in the final emulsion was characterized using an NKT6100-B laser particle size analyzer from Shandong Niket Analytical Instruments Co., Ltd. The results are as follows: Figure 3 As shown.

[0057] After the reaction, the emulsion was adjusted to pH 7 with ammonia water, and the gel-like residue was removed by filtering with a wire mesh to obtain the water-based pressure-sensitive adhesive emulsion. Trimethylolpropane-tris[3-(2-methylacridinyl)propionate] 0.38 g was added to the emulsion as a crosslinking agent. The water-based pressure-sensitive adhesive emulsion was then evenly coated onto the surface of a release film (S75TA3, release force 5-8 gf / ml, 75 μm, Shenzhen Shunhexing Electronic Materials Co., Ltd.) that had undergone corona treatment (the corona treatment process parameters were: plasma treatment time 180 seconds, treatment distance 5 cm, corona treatment voltage 30 volts).

[0058] The aqueous pressure-sensitive adhesive emulsion is milky white with a bluish tint. The emulsion is fine, with no obvious particulate gel residue, and has a minimal residual monomer odor.

[0059] Take approximately 2 g of the final emulsion and place it in an aluminum tray. Then, place the tray in a 120°C forced-air drying oven. Remove the tray and weigh it every 30 minutes until the weight remains constant. The solid content is the ratio of the remaining mass of the emulsion after drying to the mass of the emulsion sample.

[0060] The final emulsion solids content of Example 2 was approximately 56%.

[0061] The release film coated with emulsion is placed in a 60°C oven and cured for 30 minutes. The release film is then used to cover the adhesive layer to produce a water-based pressure-sensitive adhesive tape with an adhesive layer thickness of approximately 200µm.

[0062] Example 3 Preparation of bio-based waterborne pressure-sensitive adhesive latex Includes the following steps: Add 30.95 g of deionized water, then 3.81 g of OP-10 and 1.91 g of sodium dodecyl sulfate to a pre-emulsification vessel. Heat to 50°C and start mechanical stirring at 600 rpm. Then, add 30.74 g of n-butyl acrylate, 50.92 g of dibutyl fumarate, 2.55 g of acrylic acid, and 0.25 g of sodium bicarbonate in sequence at a rate of 6 ml / min. After pre-emulsification for 60 min, remove the monomer pre-emulsion for later use.

[0063] 23.75 g of deionized water, 0.95 g of OP-10, and 0.475 g of sodium dodecyl sulfate were added to the reactor. The temperature was raised to 70°C, and the stirring speed was set to 250 rpm. Then, 1.01 g of potassium persulfate initiator, soluble in 20.37 g of deionized water, was added to the reactor at a rate of 1.1 ml / min. Subsequently, 8.48 g of monomer pre-emulsion was added at once. After reacting for 30 min, the mixture was removed to obtain the seed emulsion for later use.

[0064] The seed emulsion should appear distinctly bluish-white in dim light.

[0065] Take out the prepared seed emulsion and add it to the reaction vessel. Heat it to 70°C and set the stirring speed to 250 rpm. Dissolve 0.61 g of potassium persulfate initiator in 13.15 g of deionized water. Use a peristaltic pump to slowly add the remaining monomer pre-emulsion (at a rate of 1.1 ml / min) and potassium persulfate aqueous solution (at a rate of 0.08 ml / min) to the reaction vessel over 4 h.

[0066] During the reaction, the emulsion gradually changed from bluish-white to milky white.

[0067] The final emulsion after the reaction was completed was removed, and the particle size distribution of the latex particles in the final emulsion was characterized using a laser particle size analyzer. The results are as follows: Figure 3 As shown.

[0068] After the reaction, the emulsion was adjusted to pH 7 with ammonia water, and the gel-like residue was removed by filtering with a wire mesh to obtain the water-based pressure-sensitive adhesive emulsion. 0.41 g of trimethylolpropane-tris[3-(2-methylacridinyl)propionate] was added to the emulsion as a crosslinking agent, and the water-based pressure-sensitive adhesive emulsion was evenly coated onto the corona-treated release film surface using a coating rod.

[0069] The aqueous pressure-sensitive adhesive emulsion is milky white with a bluish tint. The emulsion is fine, with no obvious particulate gel residue, and has a minimal residual monomer odor.

[0070] Take approximately 2 g of the final emulsion and place it in an aluminum tray. Then, place the tray in a 120°C forced-air drying oven. Remove the tray and weigh it every 30 minutes until the weight remains constant. The solid content is the ratio of the remaining mass of the emulsion after drying to the mass of the emulsion sample.

[0071] The final emulsion solids content of Example 3 is approximately 55%.

[0072] The release film coated with emulsion is placed in a 60°C oven and cured for 30 minutes. The release film is then used to cover the adhesive layer to produce a water-based pressure-sensitive adhesive tape with an adhesive layer thickness of approximately 200µm.

[0073] Comparative Example 1 Preparation of bio-based waterborne pressure-sensitive adhesive latex.

[0074] Includes the following steps: Add 30.55 g of deionized water to a pre-emulsification vessel, followed by 2.90 g of alkylphenol polyoxyethylene ether-10 and 1.00 g of sodium dodecyl sulfate. Heat to 50°C and start mechanical stirring at 600 rpm. Then, add 44.20 g of n-butyl acrylate, 44.22 g of dibutyl fumarate, 1.79 g of acrylic acid, and 0.18 g of sodium bicarbonate sequentially at a rate of 6 ml / min. After pre-emulsification for 60 min, remove the monomer pre-emulsion for later use.

[0075] Add 30.51 g of deionized water, 0.79 g of OP-10, and 0.25 g of sodium dodecyl sulfate to the reactor. Heat to 70°C and set the stirring speed to 250 rpm. Then, add 1.04 g of potassium persulfate initiator, soluble in 20.99 g of deionized water, to the reactor at a rate of 1.1 ml / min. Subsequently, add 8.34 g of monomer pre-emulsion all at once. After reacting for 20 min, the seed emulsion is obtained for later use.

[0076] The seed emulsion should appear distinctly bluish-white in dim light.

[0077] Take out the prepared seed emulsion and add it to the reaction vessel. Heat it to 70°C and set the stirring speed to 250 rpm. Dissolve 0.45 g of potassium persulfate initiator in 10.03 g of deionized water. Use a peristaltic pump or separatory funnel to slowly add the remaining monomer pre-emulsion (at a rate of 0.7-1.1 ml / min) and potassium persulfate aqueous solution (at a rate of 0.05-0.08 ml / min) to the reaction vessel over 4 h.

[0078] During the reaction, the emulsion gradually changed from bluish-white to milky white.

[0079] The final emulsion after the reaction was completed was removed, and the particle size distribution of the latex particles in the final emulsion was characterized using a laser particle size analyzer. The results are as follows: Figure 3 As shown.

[0080] After the reaction, the emulsion is adjusted to pH 7 with ammonia water, and the gel-like residue is removed by filtering with a wire mesh to obtain the water-based pressure-sensitive adhesive emulsion. 0.38 g of trimethylolpropane-tris[3-(2-methylacridinyl)propionate] is added to the emulsion as a crosslinking agent, and the water-based pressure-sensitive adhesive emulsion is evenly coated onto the surface of a mirror-finished stainless steel substrate or a corona-treated release film using a coating rod.

[0081] The aqueous pressure-sensitive adhesive emulsion is milky white with a bluish tint. The emulsion is fine, with no obvious particulate gel residue, and has a minimal residual monomer odor.

[0082] Take approximately 2 g of the final emulsion and place it in an aluminum tray. Then, place the tray in a 120°C forced-air drying oven. Remove the tray and weigh it every 30 minutes until the weight remains constant. The solid content is the ratio of the remaining mass of the emulsion after drying to the mass of the emulsion sample.

[0083] The final emulsion solids content in Comparative Example 1 was approximately 50%.

[0084] The release film coated with emulsion is placed in a 60°C oven and cured for 30 minutes. The release film is then used to cover the adhesive layer to produce a water-based pressure-sensitive adhesive tape with an adhesive layer thickness of approximately 200µm.

[0085] The initial tack of the pressure-sensitive adhesive tape was tested according to the test method (GB / T4852-2002), with the size of the rolling ball determining the initial tack; the larger the rolling ball, the stronger the initial tack. The holding power of the adhesive tape was tested according to the test method (GB / T 4851-2014), with the time to detach determining the holding power; the longer the time, the stronger the holding power.

[0086] Table 1 Service performance test results of the embodiments

[0087] Figure 1 Synthetic route for bio-based water-based pressure-sensitive adhesives using fumaric acid.

[0088] Figure 2 Infrared spectrum of emulsion demulsification and precipitation in Example 1, located at 1750 cm⁻¹. -1 The characteristic peak of the C=O stretching vibration is found on the ester groups of the side chains of n-butyl acrylate and dibutyl fumarate, and it is not present at 1645 cm⁻¹ in the figure. -1 The presence of a strong characteristic peak of C=C stretching vibration at 3000 cm⁻¹ indicates the absence of significant monomeric residues, as shown in the figure. -1 The presence of strong OH stretching vibration characteristic peaks indicates the presence of hydrogen bonds in the sample. These results demonstrate that the chemical composition of the aqueous pressure-sensitive adhesive synthesized in Example 1 is as expected.

[0089] Figure 3 The latex particle diameter distribution diagrams for Examples 1-3 and Comparative Example 1 show that latex particle size affects subsequent curing processes and final performance, but it is difficult to control latex particle size in practice. In the examples and comparative examples, efforts were made to control the latex particle size to maintain a single peak and a relatively uniform distribution.

Claims

1. A method for preparing a bio-based water-based pressure-sensitive adhesive with high biocarbon content, characterized in that, The high biocarbon content bio-based water-based pressure-sensitive adhesive is made from raw materials comprising the following components, wherein, by weight, the raw materials include: 280-380 parts deionized water, 1-3 parts sodium bicarbonate, 25-35 parts emulsifier, 180-280 parts soft monomer S1, 200-300 parts hard monomer S2, 5-12 parts functional monomer, 5-12 parts persulfate initiator, and aziridine crosslinking agent; the emulsifier is alkyl sulfate anionic surfactant A and polyoxyethylene ether nonionic surfactant B; The soft monomer S1 is at least one of n-butyl acrylate and 2-ethylhexyl acrylate; The hard monomer S2 is dibutyl fumarate; The functional monomer is at least one of acrylic acid and 4-hydroxybutyl acrylate; The aziridine crosslinking agent is trimethylolpropane-tris[3-(2-methylaziridine)propionate]; The alkyl sulfate anionic surfactant A is sodium dodecyl sulfate; the polyoxyethylene ether nonionic surfactant B is OP-10; and the persulfate initiator is potassium persulfate. The method does not use organic solvents and includes the following steps: (a) Preparation of monomer preemulsion: Weigh deionized water and emulsifier, add them to the emulsification tank and stir. Then add soft monomer, hard monomer, functional monomer and sodium bicarbonate in sequence and stir evenly to obtain monomer preemulsion. In the monomer preemulsion, the mass ratio of soft monomer to hard monomer ranges from 1:1.1 to 1.

7. In the monomer preemulsion, the functional monomer accounts for 2-4 wt% of the total mass of the three monomers. In the monomer preemulsion, the mass percentage of deionized water is 20-40 wt%. (b) Weigh deionized water and emulsifier, add them to the reactor and stir and heat to 70-85°C. Add 3-6 wt% of the total amount of monomer pre-emulsion obtained in step (a) to the reactor, add some initiator and deionized water, and polymerize for 25-35 minutes. The mass ratio of deionized water and emulsifier added to the reactor is in the range of 28-45:1; The initiator added to the reactor is 30% to 70% of the total mass of the initiator; The mass ratio of initiator to emulsifier is 0.2~0.8:1; (c) Add the remaining monomer pre-emulsion, remaining initiator and deionized water dropwise into the reactor over 3-4 hours; (d) After the reaction is complete, adjust the pH and viscosity, add 0.4-0.8 wt% of a aziridine crosslinking agent to the emulsion, coat and dry to prepare an aqueous pressure-sensitive adhesive.

2. The method according to claim 1, characterized in that, In step (a), the mass percentage of deionized water in the monomer preemulsion is 23-27 wt%.

3. The method according to claim 1, characterized in that, In step (a), the monomers in the monomer preemulsion should be added in order of increasing polarity.

4. The method according to claim 1, characterized in that, In step (a), the total amount of the two emulsifiers in the monomer preemulsion is 2.5-5 wt% of the monomer. During the monomer pre-emulsification process, the emulsification temperature is 25-50℃; During the monomer pre-emulsification process, the emulsification time is 30 min-120 min.

5. The method according to claim 1, characterized in that, In step (b), the deionized water added to the reactor is 25-40 wt% of the monomer. The total amount of the two emulsifiers added to the reactor is 1-1.5 wt% of the monomer.

6. The method according to claim 1, characterized in that, In step (b), the mass fraction of the monomer preemulsion added first is 3-10 wt%. In step (b), the obtained polymer emulsion has a particle size of 50-200 nanometers; In step (b), the initiator added is 30-45 wt% of the total initiator amount.

7. The bio-based water-based pressure-sensitive adhesive with high biocarbon content prepared by the method of claim 1.

8. The application of the pressure-sensitive adhesive according to claim 7, characterized in that, The pressure-sensitive adhesive emulsion is used to make pressure-sensitive adhesive tape. The following steps are required to make the pressure-sensitive adhesive emulsion into pressure-sensitive adhesive tape: (1) Adjust the pH value to 7 with ammonia water after discharging from the reactor; (2) Remove the scum by vacuum filtration to obtain the water-based pressure-sensitive latex; (3) Add 0.4-0.8 wt% of crosslinking agent based on the monomer mass, and stir thoroughly; (4) The water-based pressure-sensitive adhesive emulsion is coated onto the release film or substrate, and the excess moisture is dried in a forced-air drying oven and covered with a release film for protection.

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