Emulsion type low-VOC (volatile organic compound) acrylate pressure-sensitive adhesive based on synergistic regulation of hydrolysis mechanism, preparation method of emulsion type low-VOC acrylate pressure-sensitive adhesive and adhesive tape

Abstract

The invention discloses an emulsion type low-VOC (volatile organic compound) acrylate pressure-sensitive adhesive based on synergistic regulation and control of a hydrolysis mechanism, a preparation method thereof and an adhesive tape. According to the method provided by the invention, the pH environment of a polymerization system, the nucleation mode of the monomers and the dosage of the priming initiator are cooperatively regulated, so that the hydrolysis side reaction of the monomers can be effectively inhibited, efficient and uniform polymerization is ensured, and finally, a pressure-sensitive adhesive product with low VOC content is obtained; the acrylate pressure-sensitive adhesive prepared by the preparation method disclosed by the invention effectively reduces VOC (Volatile Organic Compounds) substances generated in a hydrolysis process, is more environment-friendly and can be used in a relatively harsh scene.

Description

Technical Field

[0001] This invention relates to the field of [field], and particularly to an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on synergistic regulation of hydrolysis mechanism, its preparation method, and the tape thereof. Background Technology

[0002] Acrylic emulsion pressure-sensitive adhesives (PSAs) are widely used in tapes, labels, and protective films due to their environmental friendliness, safety, non-toxicity, and mature production processes. However, traditional emulsion PSAs still release a certain amount of volatile organic compounds (VOCs) during production and use, impacting human health and the environment. Therefore, developing low-VOC or even zero-VOC emulsion PSAs has become an important development direction for the industry. These VOCs mainly originate from: 1) unreacted monomer residues; 2) low-molecular-weight organic compounds generated by side reactions during synthesis, such as aldehydes (formaldehyde, acetaldehyde), ketones (acetone), and various alcohol ether esters. At its root, the formation of many VOC byproducts is closely related to the hydrolysis of monomers during polymerization. In particular, monomers containing ester groups (such as ethyl acrylate (EA) and butyl acrylate (BA) are prone to hydrolysis under alkaline or high-temperature conditions, generating corresponding acrylic acid and alcohols (such as ethanol and butanol). These alcohols themselves are VOCs, and an unexpected increase in acrylic acid content can alter the copolymerization rate, affecting polymerization stability and potentially leading to more unreacted monomer residues. Furthermore, the alcohols produced by hydrolysis may undergo further side reactions such as oxidation, generating small-molecule VOCs such as aldehydes and ketones. Existing technologies often employ post-processing (such as vacuum devolatilization and steam distillation) or the addition of deodorizing agents to reduce VOCs, but these methods are costly, inefficient, and may affect product performance. Controlling VOC generation at the source—unreacted monomers and side reactions—i.e., at the polymerization mechanism level, particularly by inhibiting the hydrolysis pathway, is a more fundamental and economical solution. Currently, there is a lack of an economical, efficient, and simple method for preparing pressure-sensitive adhesives that can reduce VOCs at the source. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism, its preparation method and the tape thereof.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: In its first aspect, the present invention provides an emulsion-type low-VOC acrylic pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism, comprising the following raw material components by weight: Emulsifier 0.1-2 parts, molecular weight regulator 0.05-0.5 parts, n-butyl acrylate 50-120 parts, acrylic acid 0.5-4 parts, n-butyl methacrylate 5-20 parts, methyl acrylate 5-10 parts, hydroxyethyl acrylate 2-10 parts, first initiator 0.2-2 parts, second initiator 0.05-0.25 parts, reducing agent 0.2-2 parts, pH adjuster 0.1%-2 parts, water 70-150 parts.

[0005] Preferably, the emulsifier is sodium dodecyl sulfonate.

[0006] Preferably, the molecular weight regulator is dodecyl mercaptan.

[0007] Preferably, the first initiator is potassium persulfate and the second initiator is AIBN.

[0008] Preferably, the reducing agent is sodium sulfite.

[0009] Preferably, the pH adjuster is ammonium bicarbonate.

[0010] Preferably, the raw materials for preparing the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of the hydrolysis mechanism also include ammonia water, and the amount of ammonia water is controlled to make the pH value of the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of the hydrolysis mechanism reach 7-8.

[0011] A second aspect of the present invention provides a method for preparing an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism as described above, characterized by comprising the following steps: S0. Separate the emulsifier, deionized water, and pH adjuster into two parts respectively; S1. Preparation of pre-emulsion: S1-1. Mix the first part of the emulsifier with the first part of the deionized water to obtain mixture 1; S1-2. Mix n-butyl acrylate, acrylic acid, n-butyl methacrylate, hydroxyethyl acrylate, methyl acrylate, molecular weight regulator, and second initiator to obtain mixture 2; S1-3. Add the resulting mixture 2 dropwise to mixture 1, and stir after the addition is complete to obtain a pre-emulsion. S2, Emulsion polymerization: Mix the first part of pH adjuster, the second part of emulsifier, and the second part of deionized water to obtain mixture 3. Heat the mixture to 82-84℃, add a portion of pre-emulsion, and react for 15-60 minutes. Then, add the remaining pre-emulsion, the first initiator, the reducing agent, and the second part of pH adjuster dropwise to mixture 3 simultaneously, controlling the addition to be completed within -14 hours. Then, heat the mixture to 85-86℃ and keep it at that temperature for 1-4 hours. After cooling, add ammonia to adjust the pH value to 7-8. Filter and discard the filter residue to obtain the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism.

[0012] Preferably, the preparation method of the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism includes the following steps: S0. Separate the emulsifier, deionized water, and pH adjuster into two parts respectively; S1. Preparation of pre-emulsion: S1-1. Mix the first part of the emulsifier with the first part of the deionized water to obtain mixture 1; S1-2. Mix n-butyl acrylate, acrylic acid, n-butyl methacrylate, hydroxyethyl acrylate, methyl acrylate, molecular weight regulator, and second initiator to obtain mixture 2; S1-3. Add the obtained mixture 2 dropwise to mixture 1, and stir for 20-30 minutes after the addition is complete to obtain a pre-emulsion. S2, Emulsion polymerization: Mix the first part of pH adjuster, the second part of emulsifier, and the second part of deionized water to obtain mixture 3. Heat the mixture to 82-84℃, add a portion of the pre-emulsion, and react for 30 minutes. Then, add the remaining pre-emulsion, the first initiator, the reducing agent, and the second part of pH adjuster dropwise to mixture 3 simultaneously, controlling the addition to be completed in 2 hours. Then, heat the mixture to 85-86℃ and keep it at that temperature for 2 hours. After cooling to 50℃, add ammonia water to adjust the pH value to 7-8. Filter and discard the filter residue to obtain the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism.

[0013] In a third aspect, the present invention provides an emulsion-type low-VOC acrylate pressure-sensitive tape based on the synergistic regulation of hydrolysis mechanism, which is prepared by the following method: uniformly coating the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism as described above onto a substrate, drying and curing to obtain the emulsion-type low-VOC acrylate pressure-sensitive tape based on the synergistic regulation of hydrolysis mechanism.

[0014] The beneficial effects of this invention are: The method provided by this invention can effectively suppress the hydrolysis side reaction of monomers by synergistically controlling the pH environment of the polymerization system, the nucleation mode of monomers, and the amount of under-initiator, ensuring efficient and uniform polymerization, and finally obtaining a pressure-sensitive adhesive product with low VOC content. The acrylate pressure-sensitive adhesive prepared by this invention effectively reduces the VOC substances generated during the hydrolysis process, making it more environmentally friendly and suitable for use in more demanding environments. Attached Figure Description

[0015] Figure 1 The GC-FID spectrum of the acrylate pressure-sensitive adhesive prepared in Example 1; Figure 2 The GC-FID spectrum of the acrylate pressure-sensitive adhesive prepared in Example 2; Figure 3 The GC-FID spectrum of the acrylate pressure-sensitive adhesive prepared in Example 3; Figure 4 The GC-FID spectrum of the acrylate pressure-sensitive adhesive prepared in Example 4 is shown below. Figure 5 The GC-FID spectrum of the acrylate pressure-sensitive adhesive prepared in Comparative Example 1 is shown. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0017] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0018] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available. For examples where specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer are followed. For reagents or instruments whose manufacturers are not specified, they are all commercially available products.

[0019] This invention provides an emulsion-type low-VOC acrylic pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism, comprising the following raw material components in parts by weight: Emulsifier 0.1-2 parts, molecular weight regulator 0.05-0.5 parts, n-butyl acrylate 50-120 parts, acrylic acid 0.5-4 parts, n-butyl methacrylate 5-20 parts, methyl acrylate 5-10 parts, hydroxyethyl acrylate 2-10 parts, first initiator 0.2-2 parts, second initiator 0.05-0.25 parts, reducing agent 0.2-2 parts, pH adjuster 0.1%-2 parts, water 70-150 parts.

[0020] Preferably, the emulsifier is sodium dodecyl sulfonate.

[0021] Preferably, the molecular weight regulator is dodecyl mercaptan.

[0022] Preferably, the first initiator is potassium persulfate and the second initiator is AIBN (azobisisobutyronitrile).

[0023] Preferably, the reducing agent is sodium sulfite.

[0024] Preferably, the pH adjuster is ammonium bicarbonate.

[0025] Preferably, the raw materials for preparing the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of the hydrolysis mechanism also include ammonia water, and the amount of ammonia water is controlled so that the pH value of the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of the hydrolysis mechanism reaches 7-8.

[0026] A second aspect of the present invention provides a method for preparing an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism as described above, characterized by comprising the following steps: S0. Separate the emulsifier, deionized water, and pH adjuster into two parts respectively; S1. Preparation of pre-emulsion: S1-1. Mix the first part of the emulsifier with the first part of the deionized water to obtain mixture 1; S1-2. Mix n-butyl acrylate, acrylic acid, n-butyl methacrylate, hydroxyethyl acrylate, methyl acrylate, molecular weight regulator, and second initiator to obtain mixture 2; S1-3. Add the resulting mixture 2 dropwise to mixture 1, and stir after the addition is complete to obtain a pre-emulsion. S2, Emulsion polymerization: Mix the first part of pH adjuster, the second part of emulsifier, and the second part of deionized water to obtain mixture 3. Heat the mixture to 82-84℃, add a portion of the pre-emulsion, and react for 15-60 minutes. Then, add the remaining pre-emulsion, the first initiator, the reducing agent, and the second part of pH adjuster dropwise to mixture 3. Control the addition to be completed within -14 hours. Then, heat the mixture to 85-86℃ and keep it at that temperature for 1-4 hours. After cooling, add ammonia water to adjust the pH value to 7-8. Filter and discard the filter residue to obtain an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism.

[0027] Preferably, the preparation method of the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism includes the following steps: S0. Separate the emulsifier, deionized water, and pH adjuster into two parts respectively; S1. Preparation of pre-emulsion: S1-1. Mix the first part of the emulsifier with the first part of the deionized water to obtain mixture 1; S1-2. Mix n-butyl acrylate, acrylic acid, n-butyl methacrylate, hydroxyethyl acrylate, methyl acrylate, molecular weight regulator, and second initiator to obtain mixture 2; S1-3. Add the obtained mixture 2 dropwise to mixture 1, and stir for 20-30 minutes after the addition is complete to obtain a pre-emulsion. S2, Emulsion polymerization: Mix the first part of pH adjuster, the second part of emulsifier, and the second part of deionized water to obtain mixture 3. Heat the mixture to 82-84℃, add a portion of the pre-emulsion, and react for 30 minutes. Then, add the remaining pre-emulsion, the first initiator, the reducing agent, and the second part of pH adjuster dropwise to mixture 3, controlling the addition to be completed in 2 hours. Then, heat the mixture to 85-86℃ and keep it at that temperature for 2 hours. After cooling to 50℃, add ammonia water to adjust the pH value to 7-8. Filter and discard the filter residue to obtain an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism.

[0028] In a third aspect, the present invention provides an emulsion-type low-VOC acrylate pressure-sensitive tape based on the synergistic regulation of hydrolysis mechanism, which is prepared by the following method: the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism is uniformly coated on a substrate, dried and cured to obtain the emulsion-type low-VOC acrylate pressure-sensitive tape based on the synergistic regulation of hydrolysis mechanism.

[0029] Hydrolysis of conventional acrylate polymers is a significant mechanism leading to VOC (especially alcohols) generation and performance degradation. Essentially, it involves the scission of ester groups in the presence of water.

[0030] The reaction equation is as follows: ~~~P─COOR + H2O → P─COOH + ROH~~~ where P represents the polymer chain, R represents an alkyl group, such as butyl, isooctyl, etc., and ROH is the alcohol produced, such as butanol, isooctanol, etc.

[0031] The acrylic pressure-sensitive adhesive prepared by this invention effectively reduces VOCs generated during the hydrolysis process, making it more environmentally friendly and suitable for use in more demanding environments. Examples include automotive interiors, food packaging, labels, and medical applications. The method provided by this invention effectively suppresses monomer hydrolysis side reactions by synergistically controlling the pH environment of the polymerization system, the nucleation mode of the monomers, and the amount of the under-initializer, ensuring efficient and uniform polymerization and ultimately obtaining a pressure-sensitive adhesive product with low VOC content. Specifically, this invention incorporates at least some improvements.

[0032] A. pH value is a key factor affecting VOC generation, especially polymer hydrolysis. This invention optimizes the selection and dosage of pH adjusters: I. Selection Principles: Prioritize the use of weak bases with low volatility, such as ammonium bicarbonate. After pH adjustment, the ammonium salt formed by ammonium bicarbonate will cause the ammonia to volatilize during the drying and film formation process, preventing it from permanently remaining in the film and introducing VOCs or causing subsequent hydrolysis. Avoid using strong bases such as NaOH and KOH, as they will form non-volatile metal salts, permanently creating an alkaline environment that catalyzes subsequent hydrolysis.

[0033] II. Dosage Control: Strictly control the dosage and precisely adjust the pH to a slightly alkaline range of 6.5-7.5, which is sufficient to ensure the stability of emulsion polymerization. Excessively high or low pH values ​​will significantly accelerate ester hydrolysis, producing more alcohol VOCs.

[0034] 1. Alkaline hydrolysis, also known as saponification, is a nucleophilic addition-elimination process that is irreversible.

[0035] The reaction products obtained are: carboxylate + alcohol 2. Acidic hydrolysis is a nucleophilic addition-elimination process, but it is also reversible. The acid acts as a catalyst in this process.

[0036] The reaction products obtained are: carboxylic acid + alcohol III. Timing of pH Adjustment: Before polymerization begins, a base pH adjuster is applied to create a weakly alkaline polymerization environment in the polymerization apparatus. Due to the addition of acidic monomers, a pH adjuster is added dropwise during polymerization to further solidify the polymerization environment and reduce VOCs generated by hydrolysis.

[0037] B. Traditional water-soluble initiators tend to cause monomer nucleation in the aqueous phase, leaving a small amount of water residue in the latex particles and causing polymer hydrolysis. Oil-based initiators, on the other hand, can effectively inhibit this process. I. Mechanism of action: Oil-soluble initiators (such as azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO) dissolve in the monomer phase and mainly decompose within micelles or latex particles. They tend to initiate polymerization within the particles and can effectively inhibit nucleation in the aqueous phase, generating latex particles with more uniform particle size and better encapsulation, thereby reducing residual monomers.

[0038] II. Selection Strategy: Use oil-soluble initiators or a combination of oil-soluble and water-soluble initiators. For example, combining AIBN with ammonium persulfate (APS) in a 1:2 ratio can ensure the initial reaction rate, improve the overall conversion rate, and reduce the residual monomer content to below 0.05%.

[0039] III. Optimization of Addition Amount: The amount of oily initiator added should be controlled at 0.01%-0.5% of the total monomer mass. It mainly plays a role in reducing nucleation in the aqueous phase. Too high an amount will result in too low molecular weight and affect cohesion. "Initiator" refers to an initiator added at the initial stage of feeding to initiate the seed reaction. Its type and amount have a significant impact on VOC generation. I. Effect of Dosage: The amount of base initiator should not be excessive. Too many initial free radicals will cause a large number of crystal nuclei to be generated instantaneously, causing the reaction system to consume the emulsifier prematurely. The subsequently added monomers cannot be effectively emulsified and captured, which will instead increase the nucleation of the aqueous phase, leading to reaction instability and an increase in residual monomers. A small amount of base initiator should be used to gently generate seeds.

[0040] II. Type Selection: Choose an initiator with a moderate half-life. Initiators that decompose too quickly can lead to explosive nucleation. For persulfates (such as APS), a redox system can be formed with a reducing agent (such as NaHSO3), generating free radicals at low temperatures to achieve a mild and stable initiation reaction. This is beneficial for forming a regular latex particle structure, improving conversion rate, and reducing VOCs.

[0041] Novel Initiation System: This invention employs a system combining an oil-soluble base initiator (such as AIBN) and a water-soluble main initiator (such as APS). AIBN is introduced into the micelle system during the emulsification stage, accelerating monomer replenishment and polymerization rate within the micelles during polymerization, thereby reducing the probability of monomer nucleation in the aqueous phase and lowering VOCs.

[0042] The above is the general concept of the present invention. Based on this, detailed embodiments and comparative examples are provided below to further illustrate the present invention.

[0043] In the following examples and comparative examples, the emulsifier is sodium dodecyl sulfonate, the molecular weight regulator is dodecyl mercaptan, the reducing agent is sodium sulfite, and the pH regulator is ammonium bicarbonate.

[0044] Example 1 A method for preparing an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on synergistic regulation of hydrolysis mechanism includes the following steps: S1. Preparation of pre-emulsion: Weigh 1g of emulsifier and 80g of deionized water into an emulsification tank and mix them. Stir at 500rpm until a large amount of foam is produced. Then, add the prepared mixed monomer solution containing 100g of n-butyl acrylate, 4g of acrylic acid, 15g of n-butyl methacrylate, 5g of hydroxyethyl acrylate, 10g of methyl acrylate, 0.2g of dodecyl mercaptan, and 0.2g of AIBN into the emulsification tank at a uniform rate. Start timing after the mixed monomer solution has been added. Stir for 30 minutes to obtain the pre-emulsion.

[0045] S2, Emulsion polymerization: In a reactor equipped with a stirring paddle, condenser, and peristaltic pump feeding device, add 50g of deionized water, 0.5g of emulsifier, and 0.5g of pH adjuster. Raise the temperature inside the reactor to 82-84℃, and quickly add 20g of pre-emulsion. Control the temperature at 83±1℃ and keep it at that temperature for 30 minutes. Then, using a peristaltic pump, add the remaining pre-emulsion, 1.5g of potassium persulfate, 1g of reducing agent, and 0.7g of pH adjuster dropwise into the reactor simultaneously over 2 hours. After the dropwise addition is complete, raise the temperature to 85-86℃ and keep it at that temperature for 2 hours. Then, lower the temperature. When the temperature reaches 50℃, add ammonia water to adjust the pH value to 7.5. Filter and discard the filter residue to obtain an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of the hydrolysis mechanism.

[0046] Acrylic pressure-sensitive adhesive film was prepared by the following method: Acrylic pressure-sensitive adhesive was uniformly coated on the substrate with a coating thickness of 60 μm, and cured by baking in an oven at 120°C for 5 min to obtain acrylic pressure-sensitive adhesive film.

[0047] Example 2 A method for preparing an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on synergistic regulation of hydrolysis mechanism includes the following steps: S1. Preparation of pre-emulsion: Weigh 1g of emulsifier and 80g of deionized water into an emulsification tank and mix them at 500rpm until a large amount of foam is produced. Then, add the prepared mixed monomer solution of 100g of n-butyl acrylate, 4g of acrylic acid, 15g of n-butyl methacrylate, 5g of hydroxyethyl acrylate, 10g of methyl acrylate, 0.2g of dodecyl mercaptan, and 0.2g of AIBN into the emulsification tank at a uniform speed. Start timing after the mixed monomer solution has been added and stir for 30 minutes to obtain the pre-emulsion.

[0048] S2, Emulsion polymerization: In a reactor equipped with a stirring paddle, condenser, and peristaltic pump feeding device, add 50g of deionized water, 0.5g of emulsifier, and 0.5g of pH adjuster. Raise the temperature inside the reactor to 82-84℃, and quickly add 20g of pre-emulsion and 0.5g of potassium persulfate. Control the temperature at 83±1℃ and keep it at that temperature for 30 minutes. Then, using a peristaltic pump, add the remaining pre-emulsion, 1g of potassium persulfate, and 1g of reducing agent dropwise into the reactor simultaneously over 2 hours. After the addition is complete, raise the temperature to 85-86℃ and keep it at that temperature for 2 hours. Then, lower the temperature. When the temperature reaches 50℃, add ammonia to adjust the pH value to 7.5. Filter and discard the filter residue to obtain an emulsion-type low-VOC acrylic pressure-sensitive adhesive based on the synergistic regulation of the hydrolysis mechanism.

[0049] Acrylic pressure-sensitive adhesive film was prepared by the following method: Acrylic pressure-sensitive adhesive was uniformly coated on the substrate with a coating thickness of 60 μm, and cured by baking in an oven at 120°C for 5 min to obtain acrylic pressure-sensitive adhesive film.

[0050] Example 3 A method for preparing an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on synergistic regulation of hydrolysis mechanism includes the following steps: S1. Preparation of pre-emulsion: Weigh 1g of emulsifier and 80g of deionized water into an emulsification tank and mix them at 500rpm until a large amount of foam is produced. Then, add the prepared mixed monomer solution of 100g of n-butyl acrylate, 4g of acrylic acid, 15g of n-butyl methacrylate, 5g of hydroxyethyl acrylate, 10g of methyl acrylate, and 0.2g of dodecyl mercaptan into the emulsification tank at a uniform speed. Start timing after the mixed monomer solution has been added and stir for 30 minutes to obtain the pre-emulsion.

[0051] S2, Emulsion polymerization: In a reactor equipped with a stirring paddle, condenser, and peristaltic pump feeding device, add 50g of deionized water, 0.5g of emulsifier, and 0.5g of pH adjuster. Raise the temperature inside the reactor to 82-84℃, and quickly add 20g of pre-emulsion and 0.5g of potassium persulfate. Control the temperature at 83±1℃ and keep it at that temperature for 30 minutes. Then, using a peristaltic pump, add the remaining pre-emulsion, 1g of potassium persulfate, 1g of reducing agent, and 0.7g of pH adjuster dropwise into the reactor simultaneously over 2 hours. After the dropwise addition is complete, raise the temperature to 85-86℃ and keep it at that temperature for 2 hours. Then, lower the temperature. When the temperature reaches 50℃, add ammonia water to adjust the pH value to 7.5. Filter and discard the filter residue to obtain an emulsion-type low-VOC acrylic pressure-sensitive adhesive based on the synergistic regulation of the hydrolysis mechanism.

[0052] Acrylic pressure-sensitive adhesive film was prepared by the following method: Acrylic pressure-sensitive adhesive was uniformly coated on the substrate with a coating thickness of 60 μm, and cured by baking in an oven at 120°C for 5 min to obtain acrylic pressure-sensitive adhesive film.

[0053] Example 4 A method for preparing an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on synergistic regulation of hydrolysis mechanism includes the following steps: S1. Preparation of pre-emulsion: Weigh 1g of emulsifier and 80g of deionized water into an emulsification tank and mix them at 500rpm until a large amount of foam is produced. Then, add the prepared mixed monomer solution of 100g of n-butyl acrylate, 4g of acrylic acid, 15g of n-butyl methacrylate, 5g of hydroxyethyl acrylate, 10g of methyl acrylate, 0.2g of dodecyl mercaptan, and 0.2g of AIBN into the emulsification tank at a uniform speed. Start timing after the mixed monomer solution has been added and stir for 30 minutes to obtain the pre-emulsion.

[0054] S2, Emulsion polymerization: In a reactor equipped with a stirrer, condenser, and peristaltic pump feeding device, add (50g deionized water, 0.5g emulsifier, 0.5g pH adjuster). Raise the temperature inside the reactor to 82-84℃, and quickly add 20g of pre-emulsion and 0.5g of potassium persulfate. Control the temperature at 83±1℃ and keep it at that temperature for 30 minutes. Then, using a peristaltic pump, add the remaining pre-emulsion, 1g of potassium persulfate, 1g of reducing agent, and 0.7g of pH adjuster dropwise into the reactor simultaneously over 2 hours. After the dropwise addition is complete, raise the temperature to 85-86℃ and keep it at that temperature for 2 hours. Then, lower the temperature. When the temperature reaches 50℃, add ammonia to adjust the pH value to 7.5. Filter and discard the filter residue to obtain an emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of the hydrolysis mechanism.

[0055] Acrylic pressure-sensitive adhesive film was prepared by the following method: Acrylic pressure-sensitive adhesive was uniformly coated on the substrate with a coating thickness of 60 μm, and cured by baking in an oven at 120°C for 5 min to obtain acrylic pressure-sensitive adhesive film.

[0056] Comparative Example 1 A method for preparing an acrylic pressure-sensitive adhesive includes the following steps: S1. Preparation of pre-emulsion: Weigh 1g of emulsifier and 80g of deionized water into an emulsification tank and mix them at 500rpm until a large amount of foam is produced. Then, add the prepared mixed monomer solution of 100g of n-butyl acrylate, 4g of acrylic acid, 15g of n-butyl methacrylate, 5g of hydroxyethyl acrylate, 10g of methyl acrylate, and 0.2g of dodecyl mercaptan into the emulsification tank at a uniform speed. Start timing after the mixed monomer solution has been added and stir for 30 minutes to obtain the pre-emulsion.

[0057] S2, Emulsion polymerization: In a reactor equipped with a stirring paddle, condenser, and peristaltic pump feeding device, add 50g of deionized water, 0.5g of emulsifier, and 0.5g of pH adjuster. Raise the temperature inside the reactor to 82-84℃, and quickly add 20g of pre-emulsion. Control the temperature at 83±1℃ and keep it at that temperature for 30 minutes. Then, using a peristaltic pump, add the remaining pre-emulsion, 1.5g of potassium persulfate, and 1g of reducing agent dropwise into the reactor simultaneously over 2 hours. After the addition is complete, raise the temperature to 85-86℃ and keep it at that temperature for 2 hours. Then, lower the temperature. When the temperature reaches 50℃, add ammonia to adjust the pH value to 7.5. Filter and discard the filter residue to obtain an emulsion-type low-VOC acrylic pressure-sensitive adhesive based on the synergistic regulation of the hydrolysis mechanism.

[0058] Acrylic pressure-sensitive adhesive film was prepared by the following method: Acrylic pressure-sensitive adhesive was uniformly coated on the substrate with a coating thickness of 60 μm, and cured by baking in an oven at 120°C for 5 min to obtain acrylic pressure-sensitive adhesive film.

[0059] The VOC content of the acrylate pressure-sensitive adhesive films obtained in the above examples and comparative examples was tested using headspace gas chromatography according to the method of PV3341. The total VOC value and the n-butanol VOC value were calculated. The results are as follows: By comparing the test data in the table, it can be seen that by introducing methods such as adjusting the polymerization environment, using a base initiator, and adding an oily initiator to reduce aqueous phase nucleation during acrylate emulsion polymerization, the VOCs generated by the hydrolysis of acrylate pressure-sensitive adhesives can be effectively reduced.

[0060] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A low-VOC acrylate pressure-sensitive adhesive emulsion based on synergistic regulation of hydrolysis mechanism, characterized in that, Includes the following raw material components by weight: Emulsifier 0.1-2 parts, molecular weight regulator 0.05-0.5 parts, n-butyl acrylate 50-120 parts, acrylic acid 0.5-4 parts, n-butyl methacrylate 5-20 parts, methyl acrylate 5-10 parts, hydroxyethyl acrylate 2-10 parts, first initiator 0.2-2 parts, second initiator 0.05-0.25 parts, reducing agent 0.2-2 parts, pH adjuster 0.1%-2 parts, water 70-150 parts.

2. The emulsion-type low-VOC acrylic pressure-sensitive adhesive based on hydrolysis mechanism synergistic regulation according to claim 1, characterized in that, The emulsifier is sodium dodecyl sulfonate.

3. The emulsion-type low-VOC acrylic pressure-sensitive adhesive based on hydrolysis mechanism synergistic regulation according to claim 1, characterized in that, The molecular weight regulator is dodecyl mercaptan.

4. The emulsion-type low-VOC acrylic pressure-sensitive adhesive based on hydrolysis mechanism synergistic regulation according to claim 1, characterized in that, The first initiator is potassium persulfate, and the second initiator is AIBN.

5. The emulsion-type low-VOC acrylic pressure-sensitive adhesive based on hydrolysis mechanism synergistic regulation according to claim 1, characterized in that, The reducing agent is sodium sulfite.

6. The emulsion-type low-VOC acrylic pressure-sensitive adhesive based on hydrolysis mechanism synergistic regulation according to claim 1, characterized in that, The pH adjuster is ammonium bicarbonate.

7. The emulsion-type low-VOC acrylic pressure-sensitive adhesive based on hydrolysis mechanism synergistic regulation according to claim 1, characterized in that, The raw materials used in its preparation also include ammonia water. The amount of ammonia water is controlled to ensure that the pH value of the emulsion-type low-VOC acrylate pressure-sensitive adhesive, which is based on the synergistic regulation of the hydrolysis mechanism, reaches 7-8.

8. A method for preparing an emulsion-type low-VOC acrylic pressure-sensitive adhesive based on synergistic regulation of hydrolysis mechanism as described in any one of claims 1-7, characterized in that, Includes the following steps: S0. Separate the emulsifier, deionized water, and pH adjuster into two parts respectively; S1. Preparation of pre-emulsion: S1-1. Mix the first part of the emulsifier with the first part of the deionized water to obtain mixture 1; S1-2. Mix n-butyl acrylate, acrylic acid, n-butyl methacrylate, hydroxyethyl acrylate, methyl acrylate, molecular weight regulator, and second initiator to obtain mixture 2; S1-3. Add the resulting mixture 2 dropwise to mixture 1, and stir after the addition is complete to obtain a pre-emulsion. S2, Emulsion polymerization: Mix the first part of pH adjuster, the second part of emulsifier, and the second part of deionized water to obtain mixture 3. Heat the mixture to 82-84℃, add a portion of pre-emulsion, and react for 15-60 minutes. Then, add the remaining pre-emulsion, the first initiator, the reducing agent, and the second part of pH adjuster dropwise to mixture 3 simultaneously, controlling the addition to be completed within -14 hours. Then, heat the mixture to 85-86℃ and keep it at that temperature for 1-4 hours. After cooling, add ammonia to adjust the pH value to 7-8. Filter and discard the filter residue to obtain the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism.

9. The preparation method of the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism according to claim 8, characterized in that, Includes the following steps: S0. Separate the emulsifier, deionized water, and pH adjuster into two parts respectively; S1. Preparation of pre-emulsion: S1-1. Mix the first part of the emulsifier with the first part of the deionized water to obtain mixture 1; S1-2. Mix n-butyl acrylate, acrylic acid, n-butyl methacrylate, hydroxyethyl acrylate, methyl acrylate, molecular weight regulator, and second initiator to obtain mixture 2; S1-3. Add the obtained mixture 2 dropwise to mixture 1, and stir for 20-30 minutes after the addition is complete to obtain a pre-emulsion. S2, Emulsion polymerization: Mix the first part of pH adjuster, the second part of emulsifier, and the second part of deionized water to obtain mixture 3. Heat the mixture to 82-84℃, add a portion of the pre-emulsion, and react for 30 minutes. Then, add the remaining pre-emulsion, the first initiator, the reducing agent, and the second part of pH adjuster dropwise to mixture 3 simultaneously, controlling the addition to be completed in 2 hours. Then, heat the mixture to 85-86℃ and keep it at that temperature for 2 hours. After cooling to 50℃, add ammonia water to adjust the pH value to 7-8. Filter and discard the filter residue to obtain the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism.

10. A low-VOC acrylate pressure-sensitive tape based on a hydrolysis mechanism and synergistic regulation, characterized in that, It is prepared by the following method: the emulsion-type low-VOC acrylate pressure-sensitive adhesive based on the synergistic regulation of hydrolysis mechanism as described in any one of claims 1-7 is uniformly coated on the substrate, dried and cured to obtain the emulsion-type low-VOC acrylate pressure-sensitive adhesive tape based on the synergistic regulation of hydrolysis mechanism.

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