Water-based low-viscosity acrylic pressure-sensitive adhesive, protective film tape and preparation method thereof

Abstract

The present invention discloses a water-based low-viscosity acrylic pressure-sensitive adhesive, a protective film, a preparation method and an application, wherein the low-viscosity acrylic polymer emulsion in the water-based low-viscosity acrylic pressure-sensitive adhesive is made of raw materials including the following components by weight: 30 to 45 parts of acrylic soft monomer, 0.5 to 6.0 parts of acrylic functional monomer, 2.0 to 8.0 parts of hard monomer, 0.2 to 1.3 parts of initiator, 0.2 to 1.0 parts of pH stabilizer, 1.2 to 3.0 parts of emulsifier, 45 to 55 parts of deionized water, wherein the initiator is a redox system initiator, and the emulsifier is a reactive emulsifier with allyl groups. The protective film tape prepared from the water-based low-viscosity acrylic pressure-sensitive adhesive of the present invention has a low 180° peeling force, good exhaust performance, good temperature resistance, good late stability, is easy to remove after use, has no residual glue, and is environmentally friendly and low in cost.

Description

Technical Field

[0001] The invention relates to the field of pressure-sensitive adhesives, and in particular to a water-based low-viscosity acrylic pressure-sensitive adhesive, a protective film tape and a preparation method thereof. Background Art

[0002] Protective film is a functional material made by coating pressure-sensitive adhesive on a substrate such as plastic film or paper and processed through a special process. It is mainly used to protect the surface of products or materials during the manufacturing, processing and transmission process to prevent the surface of products and materials from being contaminated and damaged. It has the characteristics of easy adhesion, easy peelability, no warping and no surface pollution. It is widely used in instruments, furniture, color steel plates, aluminum, building profiles, electronics, home appliances and automobiles.

[0003] At present, the acrylic pressure-sensitive adhesive used in the protective film industry is mainly solvent-based pressure-sensitive adhesive. Since the products that use protective films have high requirements on the performance of the protective films, the protective films are often required to have low adhesion, excellent weather resistance, wear and scratch resistance, moisture and heat resistance, solvent resistance, and long-term adhesion with the protected surface without reaction and corrosion. Although traditional solvent-based acrylic pressure-sensitive adhesives have good performance and applicability, they also cause environmental pollution due to the large-scale use of organic solvents such as ethyl acetate, toluene, and xylene. In recent years, people have paid more and more attention to environmental protection, and various countries and regions have increasingly stringent requirements for environmental protection. Therefore, environmentally friendly materials have broad development space. Traditional water-based acrylic pressure-sensitive adhesives have the characteristics of high solid content, low viscosity, and environmental protection, but their coating and drying speed is slow, which easily contaminates the product surface, limiting their application.

[0004] Traditional water-based acrylic pressure-sensitive adhesives are mainly composed of acrylic ester monomers, initiators, emulsifiers, water-based additives and other ingredients. Due to the presence of emulsifiers and water-based additives, water-based acrylic pressure-sensitive adhesives have the following problems in application: (1) Poor water resistance and moisture resistance, which limits the application of the product on products with drying requirements. At the same time, the precipitation of emulsifiers and related water-based additives will contaminate the surface of the protected product and cannot meet the application of protective films, especially protective films for electronic products; (2) Poor air exhaust performance brings appearance problems in product application; (3) The adhesion of the protective film cannot achieve low viscosity (180° peel force below 5g), and the peel force will increase significantly in the later stage. Summary of the invention

[0005] In view of the shortcomings of the prior art, the first object of the present invention is to provide a water-based low-viscosity acrylic pressure-sensitive adhesive, which does not contain an organic solvent, meets environmental protection requirements, has a low viscosity, is easy to coat, has good air discharge properties, and a low 180° peel force, and is suitable for protective film tapes.

[0006] The second object of the present invention is to provide a method for preparing the water-based low-viscosity acrylic pressure-sensitive adhesive.

[0007] The third object of the present invention is to provide a protective film tape comprising the pressure-sensitive adhesive, which has a low 180° peeling force, good air venting, good later stability, is easy to remove after use, has no residual adhesive, and is environmentally friendly and low in cost.

[0008] A fourth object of the present invention is to provide a method for preparing the protective film tape, which has the advantages of simple steps and the like.

[0009] To achieve the first purpose of the present invention, the present invention provides an aqueous low-viscosity acrylic pressure-sensitive adhesive, which includes a low-viscosity acrylic polymer emulsion, which is made of raw materials including the following components in parts by weight: 30 to 45 parts of acrylic soft monomers; 0.5 to 6.0 parts of acrylic functional monomers; 2.0 to 8.0 parts of hard monomers; 0.2 to 1.3 parts of initiators; 1.2 to 3 parts of emulsifiers; 0.2 to 1.0 parts of pH stabilizers; and 45 to 55 parts of deionized water; wherein the initiator is a redox system initiator, and the emulsifier is a reactive emulsifier with an allyl group.

[0010] In some embodiments of the present invention, the acrylic acid ester soft monomer includes one or more of butyl acrylate, isooctyl acrylate, and lauryl acrylate.

[0011] In some embodiments of the present invention, the acrylic soft monomer is a mixture of butyl acrylate and one or two of isooctyl acrylate and lauryl acrylate, and the amount of butyl acrylate is 45-55% of the total amount of the acrylic soft monomer.

[0012] In some embodiments of the present invention, the acrylic acid ester soft monomer is a mixture of butyl acrylate, isooctyl acrylate and lauryl acrylate, and the mass ratio of butyl acrylate, isooctyl acrylate and lauryl acrylate is (19-20): (10-15): (5-10).

[0013] In some embodiments of the present invention, the acrylic functional monomer includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, acrylic acid, and β-carboxyethyl acrylic acid.

[0014] In some embodiments of the present invention, the acrylic acid functional monomer is a mixture of acrylic acid and one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, and β-carboxyethyl acrylic acid, and the amount of acrylic acid is 30-50% of the total amount of acrylic acid functional monomers.

[0015] In some embodiments of the present invention, the acrylic acid functional monomer is a mixture of acrylic acid, hydroxyethyl acrylate, and β-carboxyethyl acrylic acid, and the mass ratio of acrylic acid, hydroxyethyl acrylate, and β-carboxyethyl acrylic acid is 1:

[0016] (0.5~1):1.

[0017] In some embodiments of the present invention, the hard monomer includes one or both of methyl methacrylate and vinyl acetate.

[0018] In some embodiments of the present invention, the hard monomer is a mixture of methyl methacrylate and vinyl acetate, and the mass ratio of methyl methacrylate to vinyl acetate is 1:(0.8-1.2).

[0019] In some embodiments of the present invention, the initiator includes one or more of a hydrogen peroxide-sodium bisulfite system, a persulfate-sodium bisulfite system, and a hydroperoxide-sodium sulfite system.

[0020] In some embodiments of the present invention, the emulsifier includes one or both of allyl ether sulfonate and allyl alkyl succinate sulfonate.

[0021] In some embodiments of the present invention, the pH stabilizer is NaHCO 3 .

[0022] In some embodiments of the present invention, the water-based low-viscosity acrylic pressure-sensitive adhesive further comprises a neutralizer, a wetting agent, a defoaming agent and a curing agent.

[0023] In some embodiments of the present invention, the mass ratio of the low-viscosity acrylic polymer emulsion, the neutralizer, the wetting agent, the defoaming agent and the curing agent is 100: (0.5-1.5): (0.1-0.6): (0.05-0.1):

[0024] (0.5~3.0).

[0025] In some embodiments of the present invention, the neutralizing agent is a 30% concentration ammonia solution; the wetting agent is one or both of anionic wetting agents and nonionic wetting agents; the defoaming agent is a polyester defoaming agent; and the curing agent is one or both of water-based isocyanate curing agent and aziridine curing agent.

[0026] To achieve the second purpose of the present invention, the present invention provides a method for preparing a water-based low-viscosity acrylic pressure-sensitive adhesive as described in any of the above schemes, comprising the following steps: step 1: adding a first portion of deionized water, an oxidant in a redox system initiator, and a pH stabilizer to a reactor; step 2: stirring a second portion of deionized water and an emulsifier to prepare an emulsifier solution; stirring an acrylic soft monomer, an acrylic functional monomer, and a hard monomer to prepare a monomer mixed solution; then dropping the monomer mixed solution into the emulsifier solution to prepare a monomer emulsion; stirring a portion of the reducing agent in the redox system initiator and a third portion of deionized water to prepare a first reducing agent solution for standby use; step 3: starting the reactor to stir and heat, and dropping the monomer emulsion and the first reducing agent solution into the reactor; keeping the temperature after the dropping is complete, then stirring the remaining reducing agent in the redox system initiator and the remaining deionized water to prepare a second reducing agent solution, dropping the second reducing agent solution into the reactor, and continuing the reaction to obtain a low-viscosity acrylic polymer emulsion.

[0027] In some embodiments of the present invention, in step 1, the reactor is a stainless steel reactor equipped with a thermometer, a condenser, a high-level tank and an emulsification tank.

[0028] In some embodiments of the present invention, in step 2, the stirring speed for preparing the emulsifier liquid is 80 to 100 rpm, the stirring time is 20 to 30 minutes, and the stirring is carried out in an emulsification tank; the stirring speed for preparing the monomer mixture is 30 to 60 rpm, the stirring time is 10 to 20 minutes, and the stirring is carried out in a high-level tank; when preparing the monomer emulsion, the dropwise addition time of the monomer mixture is 30 to 40 minutes, and the stirring is continued for 40 minutes after the dropwise addition is completed; the stirring for preparing the first reducing agent solution is carried out in a titration tank.

[0029] In some embodiments of the present invention, in step 3, the reactor is started and heated to 69-71°C, and maintained at this temperature for 15-30 minutes; the monomer emulsion and the first reducing agent solution are added dropwise to the reactor in two stages, 15% of the monomer emulsion and 15% of the first reducing agent solution are added dropwise in the first stage, and the dropping rate is controlled so that it takes 50-70 minutes, and 85% of the monomer emulsion and 85% of the first reducing agent solution are added dropwise in the second stage, and the dropping rate is controlled so that it takes 160-200 minutes; the insulation temperature is 69-71°C, and the insulation time is 1-2 hours; the second reducing agent solution is prepared in a titration tank; the second reducing agent solution is added dropwise to the reactor within 25-45 minutes; the temperature of the continued reaction is 69-71°C, and the time is 3-4 hours; the obtained low-viscosity acrylic polymer emulsion is a milky white emulsion.

[0030] In some embodiments of the present invention, step 4 is further included after step 3: adding low-viscosity acrylic polymer emulsion, neutralizer, wetting agent, defoaming agent and curing agent into the glue mixing container in sequence and stirring while adding, and continuing to stir for 15 to 30 minutes after the components are added to obtain a water-based acrylic pressure-sensitive adhesive.

[0031] To achieve the third object of the present invention, the present invention provides a protective film tape, which includes a substrate layer and an adhesive layer arranged on the substrate layer, and the adhesive layer is made of the water-based low-viscosity acrylic pressure-sensitive adhesive described in any of the above schemes.

[0032] To achieve the fourth object of the present invention, the present invention further provides a method for preparing a protective film tape, comprising: coating a water-based low-viscosity acrylic pressure-sensitive adhesive on one side of a substrate layer, and then drying.

[0033] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0034] The water-based low-viscosity acrylic pressure-sensitive adhesive of the present invention has good air-discharging performance, low 180° peeling force, does not use any organic solvent, has excellent environmental protection, can replace conventional solvent-based acrylic pressure-sensitive adhesive for protective film, and conforms to the trend of industrial development. The protective film tape using the water-based low-viscosity acrylic pressure-sensitive adhesive also has low 180° peeling force, good air-discharging performance, good later stability, is easy to remove after use, has no residual adhesive, and is environmentally friendly and low in cost. DETAILED DESCRIPTION

[0035] An embodiment of the present invention provides a water-based low-viscosity acrylic pressure-sensitive adhesive. The water-based low-viscosity acrylic pressure-sensitive adhesive uses water as a solvent, does not contain an organic solvent, is safe and environmentally friendly, has good exhaust properties, and has a low 180° peeling force. The adhesive is suitable for making a protective film tape. The protective film has the characteristics of easy adhesion, easy peelability, and no surface pollution. It can adhere to the protected surface for a long time without reaction and corrosion. It can be used for surface protection of products or materials in the fields of instruments, furniture, color steel plates, aluminum materials, building profiles, electronics, home appliances, and automobiles, so as to prevent the surface of products and materials from being contaminated and damaged during the process, processing, and transmission.

[0036] Specifically, the water-based low-viscosity acrylic pressure-sensitive adhesive includes a low-viscosity acrylic polymer emulsion, which is made of raw materials including the following components in parts by weight: 30 to 45 parts of acrylic soft monomers; 0.5 to 6.0 parts of acrylic functional monomers; 2.0 to 8.0 parts of hard monomers; 0.2 to 1.3 parts of initiators; 1.2 to 3 parts of emulsifiers; 0.2 to 1.0 parts of pH stabilizers; and 45 to 55 parts of deionized water. Among them, the initiator is a redox system initiator, and the emulsifier is a reactive emulsifier with allyl groups.

[0037] The water-based low-viscosity acrylic pressure-sensitive adhesive of this embodiment uses a low-viscosity acrylic polymer emulsion, which has good air-exhaust properties, low 180° peel force, water resistance and moisture resistance. It can replace conventional solvent-based acrylic pressure-sensitive adhesives for protective films. At the same time, it does not use any organic solvents and has excellent environmental protection. The use of reactive emulsifiers in this embodiment can avoid the problem of emulsifier precipitation affecting product performance during product use, while improving the water resistance and moisture resistance of the product; a variety of soft monomers, methacrylate soft monomers, and acrylic functional monomers are used in combination to synthesize acrylic polymers with special structures, so that the protective film product has good air-exhaust properties and adhesion; the use of redox system initiators can increase the rate of initiation of polymerization, reduce the requirements for polymerization process conditions, and make the polymerization reaction more sufficient. The glue formula design and synthesis formula process route are environmentally friendly and reduce the cost of the product.

[0038] In some embodiments, the raw materials of the low-viscosity acrylic polymer emulsion are composed of the following components in parts by mass: 30-45 parts of acrylic soft monomer; 0.5-6.0 parts of acrylic functional monomer; 2.0-8.0 parts of hard monomer; 0.2-1.3 parts of initiator; 1.2-3 parts of emulsifier; 0.2-1.0 parts of pH stabilizer; 45-55 parts of deionized water. The raw materials of the low-viscosity acrylic polymer emulsion do not contain other raw materials except the above components, and the raw material composition is simpler, further reducing the cost.

[0039] In some embodiments, the total weight of the acrylic ester soft monomer, acrylic functional monomer, hard monomer, initiator, emulsifier, pH stabilizer and deionized water can be 100 parts, so as to better control the dosage of each component.

[0040] In some embodiments, the weight percentage of the acrylic soft monomer in the raw material of the low viscosity acrylic polymer emulsion can be 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 39.5, 40, 41, 42, 43, 44 or 45 parts, etc.; the weight percentage of the acrylic functional monomer can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 parts, etc.; the weight percentage of the hard monomer can be 2, 3, 4, 5, 6, 7, 8 parts, etc.; the weight percentage of the initiator can be 0.2, 0.3, 0.4, 0.5, 0.6, The mass parts of the emulsifier are 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3 parts, etc.; the mass parts of the pH stabilizer are 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 part, etc.; the mass parts of deionized water are 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55 parts, etc. The mass parts of the above components can be selected according to actual needs, and the performance of the water-based low-viscosity acrylic pressure-sensitive adhesive can be reasonably adjusted without departing from the concept of this embodiment.

[0041] In some embodiments, the acrylic acid ester soft monomer includes one or more of butyl acrylate, isooctyl acrylate, and lauryl acrylate. The acrylic acid ester soft monomer has a relatively long alkyl chain, which can improve the flexibility and water resistance of the polymer.

[0042] In some embodiments, the acrylate soft monomer is preferably a mixture of butyl acrylate and one or two of isooctyl acrylate and lauric acrylate, which can better improve the initial tack, 180° peel strength, temperature resistance and gas discharge of the low-viscosity acrylate pressure-sensitive adhesive. The amount of butyl acrylate can be 45-55% of the total amount of acrylate soft monomers, such as 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, etc.

[0043] In some embodiments, the acrylic soft monomer is more preferably a mixture of butyl acrylate, isooctyl acrylate, and lauric acrylate. The use of three acrylic soft monomers can better improve the performance of low-viscosity acrylic pressure-sensitive adhesives. The mass ratio of butyl acrylate, isooctyl acrylate, and lauric acrylate can be (19-20):

[0044] (10~15):(5~10), for example, (19.5~20):(10~15):(5~10), for example, 20:10:10, 19.5:10:10, 19.5:15:5, etc.

[0045] In some embodiments, the acrylic functional monomer includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, acrylic acid, and β-carboxyethyl acrylic acid. The acrylic functional monomer has a hydroxyl group or a carboxyl group, which can give the low-viscosity acrylic pressure-sensitive adhesive properties such as easy adhesion, while ensuring that the pressure-sensitive adhesive is easy to detach, and can further solidify and cross-link, thereby improving the mechanical properties, temperature resistance, and water resistance of the pressure-sensitive adhesive.

[0046] In some embodiments, the acrylic functional monomer is preferably a mixture of acrylic acid and one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, and β-carboxyethyl acrylic acid, which can better improve the initial adhesion, 180° peeling force, temperature resistance, and exhaust performance of the low-viscosity acrylic pressure-sensitive adhesive. The amount of acrylic acid used is 30-50% of the total amount of acrylic functional monomers, such as 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, etc.

[0047] In some embodiments, the acrylic functional monomer is more preferably a mixture of acrylic acid, hydroxyethyl acrylate, and β-carboxyethyl acrylic acid, which can better improve the performance of the low-viscosity acrylic pressure-sensitive adhesive. The mass ratio of acrylic acid, hydroxyethyl acrylate, and β-carboxyethyl acrylic acid is 1: (0.5-1): 1, for example, it can be 1: 1: 1, 1: 0.5: 1, etc.

[0048] In some embodiments, the hard monomer includes one or both of methyl methacrylate and vinyl acetate. The use of the hard monomer can improve the strength and hardness of the polymer.

[0049] In some embodiments, the hard monomer is preferably a mixture of methyl methacrylate and vinyl acetate, which can better improve the initial adhesion, 180° peel strength, temperature resistance and gas discharge of the low-viscosity acrylic pressure-sensitive adhesive. The mass ratio of methyl methacrylate to vinyl acetate is 1:(0.8-1.2), such as 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, etc.

[0050] In some embodiments, the initiator includes one or more of a hydrogen peroxide-sodium bisulfite system, a persulfate-sodium bisulfite system, and a hydroperoxide-sodium sulfite system. The use of the above redox system initiator can increase the reaction rate, and the raw materials are easily available.

[0051] In some embodiments, the emulsifier includes one or both of allyl ether sulfonate and allyl alkyl succinate sulfonate. The above emulsifier has an allyl group, which can participate in the polymerization reaction of acrylate soft monomer, acrylic functional monomer and hard monomer, and combine the emulsifier into the polymer to avoid the emulsifier of the pressure-sensitive adhesive from precipitating and thus affecting the performance of the protective film tape. The sulfonate group of the emulsifier has a good emulsifying effect.

[0052] In some embodiments, the pH stabilizer is NaHCO 3 The pH stabilizer can be used as a solvent.

[0053] In some embodiments, deionized water is deionized water that has been processed by a water treatment and purification system. The deionized water can be obtained by existing methods, which will not be described in detail here.

[0054] In some embodiments, the water-based low-viscosity acrylic pressure-sensitive adhesive further includes a neutralizer, a wetting agent, a defoamer, and a curing agent. The neutralizer can further adjust the pH value of the pressure-sensitive adhesive to prevent the pressure-sensitive adhesive from reacting and corroding the protective surface; the wetting agent can further improve the coating and processing performance of the water-based low-viscosity acrylic pressure-sensitive adhesive; and the curing agent can further adjust the peeling force, temperature resistance, and later stability of the acrylic pressure-sensitive adhesive for the protective film.

[0055] In some embodiments, the mass ratio of the low-viscosity acrylic polymer emulsion, the neutralizer, the wetting agent, the defoamer and the curing agent is 100: (0.5-1.5): (0.1-0.6): (0.05-0.1): (0.5-3.0). When the ratio of each component is within the above range, the processing performance, peeling force, temperature resistance and later stability required for the application of the protective film tape can be met.

[0056] In some embodiments, the neutralizing agent is a 30% aqueous ammonia solution, which has mild alkalinity and is readily available as a raw material.

[0057] In some embodiments, the wetting agent is one or both of anionic wetting agents and nonionic wetting agents, preferably nonionic wetting agents, and nonionic wetting agents include one or more of polyoxyethylene type, polyol type, alkanolamide type, polyether type, and amine oxide type nonionic wetting agents. The wetting agent can reduce the surface energy of the pressure-sensitive adhesive and better meet the coating performance requirements. The use of nonionic wetting agents can avoid the problem of introducing ionic groups that affect product application.

[0058] In some embodiments, the defoamer is a polyester-type defoamer.

[0059] In some embodiments, the curing agent is one or both of a water-based isocyanate curing agent and an aziridine curing agent. The above curing agents have strong reaction activity, can react quickly and completely, thereby effectively improving the peeling force, temperature resistance and later stability of the pressure-sensitive adhesive.

[0060] This embodiment also provides a method for preparing a water-based low-viscosity acrylic pressure-sensitive adhesive, comprising the following steps:

[0061] Step 1: Add the first portion of deionized water, the oxidant in the redox system initiator, and the pH stabilizer into the reactor;

[0062] Step 2: Stir the second part of deionized water and emulsifier to prepare an emulsifier solution; stir the acrylic soft monomer, acrylic functional monomer and hard monomer to prepare a monomer mixed solution; then drop the monomer mixed solution into the emulsifier solution to prepare a monomer emulsion; stir part of the reducing agent in the redox system initiator and the third part of deionized water to prepare a first reducing agent solution for use;

[0063] Step 3: Start the reaction kettle, stir and heat, and drop the monomer emulsion and the first reducing agent solution into the reaction kettle; keep warm after the dropwise addition is completed, then stir the remaining reducing agent and the remaining deionized water in the redox system initiator to prepare a second reducing agent solution, drop the second reducing agent solution into the reaction kettle, and continue the reaction to obtain a low-viscosity acrylic polymer emulsion.

[0064] The above steps can be used to obtain a stable water-based low-viscosity acrylic pressure-sensitive adhesive with good performance, and the reaction conditions are mild.

[0065] In some embodiments, in step one, the reactor is a stainless steel reactor equipped with a thermometer, a condenser, a high-level tank and an emulsification tank to achieve industrial large-scale production.

[0066] In some embodiments, in step 2, the stirring speed for preparing the emulsifier solution is 80 to 100 rpm, the stirring time is 20 to 30 minutes, and the stirring is carried out in an emulsifying tank. The stirring speed for preparing the monomer mixture is 30 to 60 rpm, the stirring time is 10 to 20 minutes, and the stirring is carried out in a high-level tank. When preparing the monomer emulsion, the dropwise addition time of the monomer mixture is 30 to 40 minutes, and the stirring is continued for 40 minutes after the dropwise addition is completed. The stirring for preparing the first reducing agent solution is carried out in a titration tank. Different reserve solutions are stirred, dispersed and prepared separately in different tanks to facilitate continuous operation.

[0067] In some embodiments, in step three, the reactor is started and heated to 69-71°C, and maintained at this temperature for 15-30 minutes. The monomer emulsion and the first reducing agent solution are added dropwise to the reactor in two stages. In the first stage, 15% of the monomer emulsion and 15% of the first reducing agent solution are added dropwise, and the dripping rate is controlled so that it takes 50-70 minutes. In the second stage, 85% of the monomer emulsion and 85% of the first reducing agent solution are added dropwise, and the dripping rate is controlled so that it takes 160-200 minutes, which is convenient for controlling the reaction process. The insulation temperature is 69-71°C, and the insulation time is 1-2 hours. The preparation of the second reducing agent solution is carried out in a titration tank. The second reducing agent solution is added dropwise to the reactor within 25-45 minutes. The temperature for continuing the reaction is 69-71°C, and the time is 3-4 hours. The resulting low-viscosity acrylic polymer emulsion is a milky white emulsion. The above reaction conditions have the advantages of mild conditions and easy reaction control.

[0068] In some embodiments, step 4 is further included after step 3: low-viscosity acrylic polymer emulsion, neutralizer, wetting agent, defoaming agent and curing agent are sequentially added into the glue mixing container and stirred while adding, and stirring is continued for 15 to 30 minutes after the components are added to obtain a water-based acrylic pressure-sensitive adhesive, which can be used as a coating liquid to prepare a protective film tape.

[0069] In some embodiments, the specific preparation method of the water-based low-viscosity acrylic pressure-sensitive adhesive may include the following steps:

[0070] Step 1: Add part of deionized water, the oxidant in the redox initiator system, and the pH stabilizer into a stainless steel reactor equipped with a thermometer, a condenser, a high-level tank, and an emulsification tank;

[0071] Step 2: adding part of deionized water and emulsifier into an emulsifying tank and stirring at a stirring speed of 80 to 100 rpm for 20 to 30 minutes; adding acrylate soft monomer, acrylic functional monomer and hard monomer in a mass ratio into a high-level tank and stirring at a stirring speed of 30 to 60 rpm for 10 to 20 minutes to obtain a monomer mixture; then dripping the monomer mixture into the emulsifying tank for 30 to 40 minutes, and continuing to stir for 40 minutes after the dripping is completed to obtain a monomer emulsion; adding part of the reducing agent in the oxidation-reduction initiator system and part of the deionized water into a titration tank and stirring to obtain a first reducing agent solution for standby use;

[0072] Step 3: Start the reaction kettle, stir and heat, heat to 69-71° C., and keep the temperature for 15-30 minutes, drop the monomer emulsion and the first reducing agent solution into the reaction kettle, the dropping is carried out in two stages, in the first stage, 15% of the monomer emulsion and 15% of the first reducing agent solution are dropped, and the dropping rate is controlled so that it takes 60 minutes, and in the second stage, 85% of the monomer emulsion and 85% of the first reducing agent solution are dropped, and the dropping rate is controlled so that it takes 180 minutes; after the dropwise addition is completed, the temperature is controlled at 69-71° C. and kept warm for 1-2 hours, and then the remaining reducing agent and deionized water are added to the titration tank and stirred evenly to obtain a second reducing agent solution, and the second reducing agent solution is dropped into the reaction kettle within 30 minutes, and the temperature is continued to be controlled at 69-71° C. and kept warm for 3-4 hours to obtain a milky white low-viscosity acrylate polymer emulsion;

[0073] Step 4: Add low-viscosity acrylic polymer emulsion, neutralizer, wetting agent, defoamer and curing agent to the glue mixing container (barrel) in sequence while stirring. Continue stirring for 15 to 30 minutes after adding all the components to obtain a water-based acrylic pressure-sensitive adhesive coating liquid.

[0074] This embodiment also provides a protective film tape made of the above-mentioned water-based low-viscosity acrylic pressure-sensitive adhesive, which includes a substrate layer and an adhesive layer arranged on the substrate layer, and the adhesive layer is made of the water-based low-viscosity acrylic pressure-sensitive adhesive of any of the above-mentioned embodiments. The protective film tape has a low 180° peeling force, good air discharge, good temperature resistance, good later stability, is easy to remove after use, has no residual adhesive, and the product is environmentally friendly and low in cost. The substrate layer can be a plastic film such as a PET film, or it can be paper. The substrate layer provides support for the adhesive layer, improves the strength of the protective film tape, and facilitates the bonding and peeling of the protective film tape. The thickness ratio of the substrate layer and the adhesive layer can be (5 to 20): 1.

[0075] This embodiment also provides a method for preparing the protective film tape, comprising: coating a water-based low-viscosity acrylic pressure-sensitive adhesive on one side of the substrate layer, and then drying. The drying temperature may be 100° C. to 150° C., and the drying time may be 1 to 5 minutes, so as to facilitate the removal of water and further solidify the pressure-sensitive adhesive.

[0076] The water-based low-viscosity acrylic pressure-sensitive adhesive, protective film tape and preparation method thereof of the present invention are further described in detail below through specific examples. In the following examples and comparative examples, the raw materials with the same name have the same composition and source.

[0077] Example 1

[0078] 1. Preparation of low viscosity acrylic polymer emulsion:

[0079] 1. Raw material composition (parts by weight):

[0080] Acrylate soft monomer: butyl acrylate, 30 parts;

[0081] Acrylic acid functional monomer: acrylic acid, 4.5 parts;

[0082] Hard monomer: methyl methacrylate, 8.0 parts;

[0083] Initiator: potassium persulfate (oxidant), 0.2 parts; sodium bisulfite (reducing agent), 0.1 parts;

[0084] Emulsifier: reactive emulsifier allyl alkyl succinate sulfonate (model: SR-10, manufacturer: Aidico (China) Investment Co., Ltd.), 1.2 parts;

[0085] pH stabilizer: NaHCO 3 , 1.0 part;

[0086] Deionized water: 55.0 parts.

[0087] 2. Preparation method:

[0088] (1) Mix 30 parts of deionized water, 0.2 parts of potassium persulfate, and 1.0 parts of NaHCO 3 The solution is added into a stainless steel reactor equipped with a thermometer, condenser, header tank and emulsification tank;

[0089] (2) adding 20 parts of deionized water and 1.2 parts of reactive emulsifier allyl alkyl succinate sulfonate to an emulsifying tank and stirring at a speed of 80 rpm for 20 minutes; adding 30 parts of butyl acrylate, 4.5 parts of acrylic acid and 8.0 parts of methyl methacrylate to an overhead tank and stirring at a speed of 30 rpm for 10 minutes to obtain a monomer mixture; then dripping the monomer mixture into the emulsifying tank for 30 minutes, and stirring for 40 minutes after the dripping is completed to obtain a monomer emulsion; adding 0.08 parts of sodium bisulfite and 3.2 parts of deionized water to a titration tank and stirring to obtain a reducing agent solution 1 for standby use;

[0090] (3) Start the reaction kettle, stir and heat it to 70° C., and keep it at this temperature for 15 minutes, add the monomer emulsion and 1 drop of reducing agent solution into the reaction kettle; after the addition is completed, keep it at 70° C. for 1.5 hours, then add the remaining 0.02 parts of sodium bisulfite and 1.8 parts of deionized water into the titration tank and stir evenly to obtain reducing agent solution 2, add 2 drops of reducing agent solution into the reaction kettle within 30 minutes, and continue to keep it at 70° C. for 3.5 hours to obtain a milky white low-viscosity acrylate polymer emulsion;

[0091] The dropping in step (3) is carried out in two stages. In the first stage, 15% of the monomer emulsion and 15% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 60 minutes; in the second stage, 85% of the monomer emulsion and 85% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 180 minutes.

[0092] 2. Preparation of protective film tape:

[0093] 1. Raw material composition:

[0094] Low-viscosity acrylic emulsion prepared in step 1: 100 parts;

[0095] Neutralizer: 30% ammonia water, 1.5 parts;

[0096] Wetting agent: polyether nonionic wetting agent (model: PE6100, manufacturer: BASF China Co., Ltd.), 0.6 parts;

[0097] Defoamer: polyester defoamer (model: S-510A, manufacturer: Dongguan Terunde Chemical Materials Co., Ltd.), 0.08 parts;

[0098] Curing agent: The amount of aziridine curing agent is 0.5 parts (No. ①), 1.5 parts (No. ②), and 3.0 parts (No. ③).

[0099] 2. Preparation method:

[0100] (1) Preparation of low-viscosity acrylic emulsion pressure-sensitive adhesive: Add the above components into a glue mixing container (barrel) in sequence while stirring. Continue stirring for 20 minutes after adding all the components to obtain a water-based acrylic emulsion pressure-sensitive adhesive.

[0101] (2) Preparation of protective film tape: The pressure-sensitive adhesive prepared in step (1) is coated on one side of a 50 μm PET substrate layer, and the protective film tape is rolled up after curing and drying. The drying temperature is 110° C. and the drying time is 2 min.

[0102] The thickness of each layer of the product is: 5μm for the pressure-sensitive adhesive layer and 50μm for the PET substrate layer.

[0103] Example 2

[0104] 1. Preparation of low viscosity acrylic polymer emulsion:

[0105] 1. Raw material composition (parts by weight):

[0106] Acrylate soft monomer: isooctyl acrylate, 45 parts;

[0107] Acrylic acid functional monomer: acrylic acid, 3.5 parts;

[0108] Hard monomer: methyl methacrylate, 2 parts;

[0109] Initiator: potassium persulfate (oxidant), 0.8 parts; sodium bisulfite (reducing agent), 0.5 parts;

[0110] Emulsifier: reactive emulsifier allyl alkyl succinate sulfonate (model: SR-10, manufacturer: Aidico (China) Investment Co., Ltd.), 3.0 parts;

[0111] pH stabilizer: NaHCO 3 , 0.2 part;

[0112] Deionized water: 45 parts.

[0113] 2. Preparation method:

[0114] (1) Mix 24 parts of deionized water, 0.8 parts of potassium persulfate, and 0.2 parts of NaHCO 3 The solution is added into a stainless steel reactor equipped with a thermometer, condenser, header tank and emulsification tank;

[0115] (2) 15 parts of deionized water and 3.0 parts of reactive emulsifier allyl alkyl succinate sulfonate are added to an emulsification tank and stirred at a speed of 80 rpm for 20 minutes; 45 parts of isooctyl acrylate, 3.5 parts of acrylic acid, and 2.0 parts of methyl methacrylate are added to a high-level tank and stirred at a speed of 30 rpm for 10 minutes to obtain a monomer mixture; then the monomer mixture is added dropwise to the emulsification tank for 30 minutes, and after the addition is completed, stirring is continued for 40 minutes to obtain a monomer emulsion; 0.4 parts of sodium bisulfite and 4.2 parts of deionized water are added to a titration tank and stirred to obtain a reducing agent solution 1 for standby use;

[0116] (3) Start the reaction kettle, stir and heat it to 70° C., and keep it at this temperature for 15 minutes, add the monomer emulsion and 1 drop of reducing agent solution into the reaction kettle; after the addition is completed, keep it at 70° C. for 1.5 hours, then add the remaining 0.1 parts of sodium bisulfite and 1.8 parts of deionized water into the titration tank and stir evenly to obtain reducing agent solution 2, add 2 drops of reducing agent solution into the reaction kettle within 30 minutes, and continue to keep it at 70° C. for 3.5 hours to obtain a milky white low-viscosity acrylate polymer emulsion;

[0117] The dropping in step (3) is carried out in two stages. In the first stage, 15% of the monomer emulsion and 15% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 60 minutes; in the second stage, 85% of the monomer emulsion and 85% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 180 minutes.

[0118] 2. Preparation of protective film tape:

[0119] 1. Raw material composition:

[0120] Low-viscosity acrylic emulsion prepared in step 1: 100 parts;

[0121] Neutralizer: 30% ammonia water, 0.5 parts;

[0122] Wetting agent: polyether nonionic wetting agent (model: PE6100, manufacturer: BASF China Co., Ltd.), 0.1 part;

[0123] Defoamer: polyester defoamer (model: S-510A, manufacturer: Dongguan Terunde Chemical Materials Co., Ltd.), 0.08 parts;

[0124] Curing agent: The amount of aziridine curing agent is 0.5 parts (No. ①), 1.5 parts (No. ②), and 3.0 parts (No. ③).

[0125] 2. Preparation method:

[0126] (1) Preparation of low-viscosity acrylic emulsion pressure-sensitive adhesive: Add the above components into a glue mixing container (barrel) in sequence while stirring. Continue stirring for 20 minutes after the components are added to obtain a water-based acrylic emulsion pressure-sensitive adhesive.

[0127] (2) Preparation of protective film tape: The pressure-sensitive adhesive prepared in step (1) is coated on one side of a 50 μm PET substrate layer, and the protective film tape is rolled up after curing and drying. The drying temperature is 110° C. and the drying time is 2 min.

[0128] The thickness of each layer of the product is: 5μm for the pressure-sensitive adhesive layer and 50μm for the PET substrate layer.

[0129] Example 3

[0130] 1. Preparation of low viscosity acrylic polymer emulsion:

[0131] 1. Raw material composition (parts by weight):

[0132] Acrylate soft monomer: butyl acrylate, 20 parts, isooctyl acrylate, 20 parts;

[0133] Acrylic acid functional monomer: acrylic acid, 1.0 part, β-carboxyethyl acrylic acid, 1.0 part;

[0134] Hard monomer: methyl methacrylate, 2.5 parts, vinyl acetate, 2.5 parts;

[0135] Initiator: potassium persulfate (oxidant), 0.5 parts; sodium bisulfite (reducing agent), 0.2 parts;

[0136] Emulsifier: reactive emulsifier allyl alkyl succinate sulfonate (model: SR-10, manufacturer: Aidico (China) Investment Co., Ltd.), 2.0 parts;

[0137] pH stabilizer: NaHCO 3 , 0.5 part;

[0138] Deionized water: 49.8 parts.

[0139] 2. Preparation method:

[0140] (1) Mix 28 parts of deionized water, 0.5 parts of potassium persulfate, and 0.5 parts of NaHCO 3 The solution is added into a stainless steel reactor equipped with a thermometer, condenser, header tank and emulsification tank;

[0141] (2) 16.0 parts of deionized water and 2 parts of reactive emulsifier allyl alkyl succinate sulfonate are added to an emulsification tank and stirred at a speed of 80 rpm for 20 minutes; 20 parts of butyl acrylate, 20 parts of isooctyl acrylate, 1.0 part of acrylic acid, 1.0 part of β-carboxyethyl acrylic acid, 2.5 parts of methyl methacrylate and 2.5 parts of vinyl acetate are added to an overhead tank and stirred at a speed of 30 rpm for 10 minutes to obtain a monomer mixture; then the monomer mixture is added dropwise to the emulsification tank for 30 minutes. After the addition is completed, stirring is continued for 40 minutes to obtain a monomer emulsion; 0.16 parts of sodium bisulfite and 4 parts of deionized water are added to a titration tank and stirred to obtain a reducing agent solution 1 for standby use;

[0142] (3) Start the reaction kettle, stir and heat it to 70° C., and keep it at this temperature for 15 minutes, add the monomer emulsion and 1 drop of reducing agent solution into the reaction kettle; after the addition is completed, keep it at 70° C. for 1.5 hours, then add the remaining 0.04 parts of sodium bisulfite and 1.8 parts of deionized water into the titration tank and stir evenly to obtain reducing agent solution 2, add 2 drops of reducing agent solution into the reaction kettle within 30 minutes, and continue to keep it at 70° C. for 3.5 hours to obtain a milky white low-viscosity acrylate polymer emulsion;

[0143] The dropping in step (3) is carried out in two stages. In the first stage, 15% of the monomer emulsion and 15% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 60 minutes; in the second stage, 85% of the monomer emulsion and 85% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 180 minutes.

[0144] 2. Preparation of protective film tape:

[0145] 1. Raw material composition:

[0146] Low-viscosity acrylic emulsion prepared in step 1: 100 parts;

[0147] Neutralizer: 30% ammonia water, 0.8 parts;

[0148] Wetting agent: polyether nonionic wetting agent (model: PE6100, manufacturer: BASF China Co., Ltd.), 0.2 parts;

[0149] Defoamer: polyester defoamer (model: S-510A, manufacturer: Dongguan Terunde Chemical Materials Co., Ltd.), 0.08 parts;

[0150] Curing agent: The amount of aziridine curing agent is 0.5 parts (No. ①), 1.5 parts (No. ②), and 3.0 parts (No. ③).

[0151] 2. Preparation method:

[0152] (1) Preparation of low-viscosity acrylic emulsion pressure-sensitive adhesive: Add the above components into a glue mixing container (barrel) in sequence while stirring. Continue stirring for 20 minutes after adding all the components to obtain a water-based acrylic emulsion pressure-sensitive adhesive.

[0153] (2) Preparation of protective film tape: The pressure-sensitive adhesive prepared in step (1) is coated on one side of a 50 μm PET substrate layer, and the protective film tape is rolled up after curing and drying. The drying temperature is 110° C. and the drying time is 2 min.

[0154] The thickness of each layer of the product is: 5μm for the pressure-sensitive adhesive layer and 50μm for the PET substrate layer.

[0155] Example 4

[0156] 1. Preparation of low viscosity acrylic polymer emulsion:

[0157] 1. Raw material composition (parts by weight):

[0158] Acrylate soft monomer: butyl acrylate, 20 parts, isooctyl acrylate, 10 parts, lauryl acrylate, 10 parts;

[0159] Acrylic acid functional monomer: acrylic acid, 1.0 part, β-carboxyethyl acrylic acid, 1.0 part;

[0160] Hard monomer: methyl methacrylate, 2.5 parts, vinyl acetate, 2.5 parts;

[0161] Initiator: potassium persulfate (oxidant), 0.5 parts; sodium bisulfite (reducing agent), 0.2 parts;

[0162] Emulsifier: reactive emulsifier allyl alkyl succinate sulfonate (model: SR-10, manufacturer: Aidico (China) Investment Co., Ltd.), 2.0 parts;

[0163] pH stabilizer: NaHCO 3 , 0.5 part;

[0164] Deionized water: 49.8 parts.

[0165] 2. Preparation method:

[0166] (1) Mix 28 parts of deionized water, 0.5 parts of potassium persulfate, and 0.5 parts of NaHCO 3 The solution is added into a stainless steel reactor equipped with a thermometer, condenser, header tank and emulsification tank;

[0167] (2) 16.0 parts of deionized water and 2 parts of reactive emulsifier allyl alkyl succinate sulfonate are added to an emulsifying tank and stirred at a speed of 80 rpm for 20 minutes; 20 parts of butyl acrylate, 10 parts of isooctyl acrylate, 10 parts of lauryl acrylate, 1.0 part of acrylic acid, 1.0 part of β-carboxyethyl acrylic acid, 2.5 parts of methyl methacrylate and 2.5 parts of vinyl acetate are added to an overhead tank and stirred at a speed of 30 rpm for 10 minutes to obtain a monomer mixture; then the monomer mixture is added dropwise to the emulsifying tank for 30 minutes. After the addition is completed, stirring is continued for 40 minutes to obtain a monomer emulsion; 0.16 parts of sodium bisulfite and 4 parts of deionized water are added to a titration tank and stirred to obtain a reducing agent solution 1 for standby use;

[0168] (3) Start the reaction kettle, stir and heat it to 70° C., and keep it at this temperature for 15 minutes, add the monomer emulsion and 1 drop of reducing agent solution into the reaction kettle; after the addition is completed, keep it at 70° C. for 1.5 hours, then add the remaining 0.04 parts of sodium bisulfite and 1.8 parts of deionized water into the titration tank and stir evenly to obtain reducing agent solution 2, add 2 drops of reducing agent solution into the reaction kettle within 30 minutes, and continue to keep it at 70° C. for 3.5 hours to obtain a milky white low-viscosity acrylate polymer emulsion;

[0169] The dropping in step (3) is carried out in two stages. In the first stage, 15% of the monomer emulsion and 15% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 60 minutes; in the second stage, 85% of the monomer emulsion and 85% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 180 minutes.

[0170] 2. Preparation of protective film tape:

[0171] 1. Raw material composition:

[0172] Low-viscosity acrylic emulsion prepared in step 1: 100 parts;

[0173] Neutralizer: 30% ammonia water, 0.8 parts;

[0174] Wetting agent: polyether nonionic wetting agent (model: PE6100, manufacturer: BASF China Co., Ltd.), 0.2 parts;

[0175] Defoamer: polyester defoamer (model: S-510A, manufacturer: Dongguan Terunde Chemical Materials Co., Ltd.), 0.08 parts;

[0176] Curing agent: The amount of aziridine curing agent is 0.5 parts (No. ①), 1.5 parts (No. ②), and 3.0 parts (No. ③).

[0177] 2. Preparation method:

[0178] (1) Preparation of low-viscosity acrylic emulsion pressure-sensitive adhesive: Add the above components into a glue mixing container (barrel) in sequence while stirring. Continue stirring for 20 minutes after adding all the components to obtain a water-based acrylic emulsion pressure-sensitive adhesive.

[0179] (2) Preparation of protective film tape: The pressure-sensitive adhesive prepared in step (1) is coated on one side of a 50 μm PET substrate layer, and the protective film tape is rolled up after curing and drying. The drying temperature is 110° C. and the drying time is 2 min.

[0180] The thickness of each layer of the product is: 5μm for the pressure-sensitive adhesive layer and 50μm for the PET substrate layer.

[0181] Example 5

[0182] 1. Preparation of low viscosity acrylic polymer emulsion:

[0183] 1. Raw material composition (parts by weight):

[0184] Acrylate soft monomer: butyl acrylate, 19.5 parts, isooctyl acrylate, 10 parts, lauryl acrylate, 10 parts;

[0185] Acrylic acid functional monomer: acrylic acid, 1.0 part, β-carboxyethyl acrylic acid, 1.0 part, hydroxyethyl acrylate, 0.5 part;

[0186] Hard monomer: methyl methacrylate, 2.5 parts, vinyl acetate, 2.5 parts;

[0187] Initiator: potassium persulfate (oxidant), 0.5 parts; sodium bisulfite (reducing agent), 0.2 parts;

[0188] Emulsifier: reactive emulsifier allyl alkyl succinate sulfonate (model: SR-10, manufacturer: Aidico (China) Investment Co., Ltd.), 2.0 parts;

[0189] pH stabilizer: NaHCO 3 , 0.5 part;

[0190] Deionized water: 49.8 parts.

[0191] 2. Preparation method:

[0192] (1) Mix 28 parts of deionized water, 0.5 parts of potassium persulfate, and 0.5 parts of NaHCO 3 The solution is added into a stainless steel reactor equipped with a thermometer, condenser, header tank and emulsification tank;

[0193] (2) 16.0 parts of deionized water and 2 parts of reactive emulsifier allyl alkyl succinate sulfonate are added to an emulsifying tank and stirred at a speed of 80 rpm for 20 minutes; 19.5 parts of butyl acrylate, 10 parts of isooctyl acrylate, 10 parts of lauryl acrylate, 1.0 part of acrylic acid, 1.0 part of β-carboxyethyl acrylic acid, 0.5 part of hydroxyethyl acrylate, 2.5 parts of methyl methacrylate and 2.5 parts of vinyl acetate are added to an overhead tank and stirred at a speed of 30 rpm for 10 minutes to obtain a monomer mixture; then the monomer mixture is added dropwise to the emulsifying tank for 30 minutes, and after the addition is completed, stirring is continued for 40 minutes to obtain a monomer emulsion; 0.16 parts of sodium bisulfite and 4 parts of deionized water are added to a titration tank and stirred to obtain a reducing agent solution 1 for standby use;

[0194] (3) Start the reaction kettle, stir and heat it to 70° C., and keep it at this temperature for 15 minutes, add the monomer emulsion and 1 drop of reducing agent solution into the reaction kettle; after the addition is completed, keep it at 70° C. for 1.5 hours, then add the remaining 0.04 parts of sodium bisulfite and 1.8 parts of deionized water into the titration tank and stir evenly to obtain reducing agent solution 2, add 2 drops of reducing agent solution into the reaction kettle within 30 minutes, and continue to keep it at 70° C. for 3.5 hours to obtain a milky white low-viscosity acrylate polymer emulsion;

[0195] The dropping in step (3) is carried out in two stages. In the first stage, 15% of the monomer emulsion and 15% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 60 minutes; in the second stage, 85% of the monomer emulsion and 85% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 180 minutes.

[0196] 2. Preparation of protective film tape:

[0197] 1. Raw material composition:

[0198] Low-viscosity acrylic emulsion prepared in step 1: 100 parts;

[0199] Neutralizer: 30% ammonia water, 0.8 parts.

[0200] Wetting agent: polyether nonionic wetting agent (model: PE6100, manufacturer: BASF China Co., Ltd.), 0.2 parts;

[0201] Defoamer: polyester defoamer (model: S-510A, manufacturer: Dongguan Terunde Chemical Materials Co., Ltd.), 0.08 parts;

[0202] Curing agent: The amount of aziridine curing agent is 0.5 parts (No. ①), 1.5 parts (No. ②), and 3.0 parts (No. ③).

[0203] 2. Preparation method:

[0204] (1) Preparation of low-viscosity acrylic emulsion pressure-sensitive adhesive: Add the above components into a glue mixing container (barrel) in sequence while stirring. Continue stirring for 20 minutes after adding all the components to obtain a water-based acrylic emulsion pressure-sensitive adhesive.

[0205] (2) Preparation of protective film tape: The pressure-sensitive adhesive prepared in step (1) is coated on one side of a 50 μm PET substrate layer, and the protective film tape is rolled up after curing and drying. The drying temperature is 110° C. and the drying time is 2 min.

[0206] The thickness of each layer of the product is: 5μm for the pressure-sensitive adhesive layer and 50μm for the PET substrate layer.

[0207] Example 6

[0208] 1. Preparation of low viscosity acrylic polymer emulsion:

[0209] 1. Raw material composition (parts by weight):

[0210] Acrylate soft monomer: butyl acrylate, 19.5 parts, isooctyl acrylate, 15 parts, lauryl acrylate, 5 parts;

[0211] Acrylic acid functional monomer: acrylic acid, 1.0 part, β-carboxyethyl acrylic acid, 1.0 part, hydroxyethyl acrylate, 1.0 part;

[0212] Hard monomer: methyl methacrylate, 2.5 parts, vinyl acetate, 2.5 parts;

[0213] Initiator: potassium persulfate (oxidant), 0.5 parts; sodium bisulfite (reducing agent), 0.2 parts;

[0214] Emulsifier: reactive emulsifier allyl alkyl succinate sulfonate (model: SR-10, manufacturer: Aidico (China) Investment Co., Ltd.), 2.0 parts;

[0215] pH stabilizer: NaHCO 3 , 0.5 part;

[0216] Deionized water: 49.3 parts.

[0217] 2. Preparation method:

[0218] (1) Mix 28 parts of deionized water, 0.5 parts of potassium persulfate, and 0.5 parts of NaHCO 3The solution is added into a stainless steel reactor equipped with a thermometer, condenser, header tank and emulsification tank;

[0219] (2) 16.0 parts of deionized water and 2 parts of reactive emulsifier allyl alkyl succinate sulfonate are added to an emulsifying tank and stirred at a speed of 80 rpm for 20 minutes; 19.5 parts of butyl acrylate, 15 parts of isooctyl acrylate, 5 parts of lauryl acrylate, 1.0 part of acrylic acid, 1.0 part of β-carboxyethyl acrylic acid, 1.0 part of hydroxyethyl acrylate, 2.5 parts of methyl methacrylate and 2.5 parts of vinyl acetate are added to an overhead tank and stirred at a speed of 30 rpm for 10 minutes to obtain a monomer mixture; then the monomer mixture is added dropwise to the emulsifying tank for 30 minutes. After the addition is completed, stirring is continued for 40 minutes to obtain a monomer emulsion; 0.16 parts of sodium bisulfite and 3.5 parts of deionized water are added to a titration tank and stirred to obtain a reducing agent solution 1 for standby use;

[0220] (3) Start the reaction kettle, stir and heat it to 70° C., and keep it at this temperature for 15 minutes, add the monomer emulsion and 1 drop of reducing agent solution into the reaction kettle; after the addition is completed, keep it at 70° C. for 1.5 hours, then add the remaining 0.04 parts of sodium bisulfite and 1.8 parts of deionized water into the titration tank and stir evenly to obtain reducing agent solution 2, add 2 drops of reducing agent solution into the reaction kettle within 30 minutes, and continue to keep it at 70° C. for 3.5 hours to obtain a milky white low-viscosity acrylate polymer emulsion;

[0221] The dropping in step (3) is carried out in two stages. In the first stage, 15% of the monomer emulsion and 15% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 60 minutes; in the second stage, 85% of the monomer emulsion and 85% of the reducing agent solution 1 are dropped, and the dropping rate is controlled so that it takes 180 minutes.

[0222] 2. Preparation of protective film tape:

[0223] 1. Raw material composition:

[0224] Low-viscosity acrylic emulsion prepared in step 1: 100 parts;

[0225] Neutralizer: 30% ammonia water, 0.8 parts;

[0226] Wetting agent: polyether nonionic wetting agent (model: PE6100, manufacturer: BASF China Co., Ltd.), 0.2 parts;

[0227] Defoamer: polyester defoamer (model: S-510A, manufacturer: Dongguan Terunde Chemical Materials Co., Ltd.), 0.08 parts;

[0228] Curing agent: The amount of aziridine curing agent is 0.5 parts (No. ①), 1.5 parts (No. ②), and 3.0 parts (No. ③).

[0229] 2. Preparation method:

[0230] (1) Preparation of low-viscosity acrylic emulsion pressure-sensitive adhesive: Add the above components into a glue mixing container (barrel) in sequence while stirring. Continue stirring for 20 minutes after adding all the components to obtain a water-based acrylic emulsion pressure-sensitive adhesive.

[0231] (2) Preparation of protective film tape: The pressure-sensitive adhesive prepared in step (1) is coated on one side of a 50 μm PET substrate layer, and the protective film tape is rolled up after curing and drying. The drying temperature is 110° C. and the drying time is 2 min.

[0232] The thickness of each layer of the product is: 5μm for the pressure-sensitive adhesive layer and 50μm for the PET substrate layer.

[0233] Comparative Example 1

[0234] This comparative example is used to illustrate the effect on product performance when no reactive emulsifier is used. This comparative example is carried out with reference to Example 1, except that 0.4 parts of anionic emulsifier (DOWFAX 2A1) and 0.8 parts of nonionic emulsifier (DOWFAX CO630) are used as emulsifiers to replace 1.2 parts of allyl alkyl succinate sulfonate, a reactive emulsifier in Example 1. The types and amounts of other components and their preparation methods are the same as those in Example 1.

[0235] Performance Testing Methods

[0236] 1. Viscosity: According to GB / T 2794-2013 "Determination of viscosity of adhesives - Single cylinder rotational viscometer method", the viscosity is measured using an electronic digital rotational viscometer at a test temperature of 23±2°C.

[0237] 2.180° peel strength: According to GB / T 2792-2014 "Test method for peel strength of adhesive tape", the peel strength tensile testing machine is used for measurement. The tape width is 25mm and the peeling rate is 300mm / min.

[0238] 3. Initial tack: According to GB / T 4852-2002 "Pressure-sensitive adhesive tape initial tack test method rolling ball method" standard, use an initial tack tester to measure at an inclination angle of 30°.

[0239] 4. Stickiness: Tested in accordance with GB / T 4851-2014. Hang the sample with the pressure-sensitive tape vertically on the test frame, hang a weight of specified mass below, and characterize the stickiness of the pressure-sensitive adhesive by the displacement of the sample sliding down in a certain period of time or the time for the sample to completely detach.

[0240] 5. Exhaust performance: In a dust-free environment, gently tear off the release film on the surface of the protective film, stick it on a smooth black glass plate, observe the wetting speed and effect of its complete adhesion on the glass plate, tear off the test sample, and repeat the film sticking operation. Exhaust performance A+: The automatic exhaust area reaches 80% or more, the exhaust time is 1 to 10 seconds, and there are no bubbles, white edges, indentations, and incomplete exhaust after exhaust. It is judged as A+; Exhaust performance A: The automatic exhaust area reaches 80% or more, the exhaust time is 10 to 20 seconds, and there are some bubbles, white edges, indentations, and incomplete exhaust after exhaust. Exhaust performance A-: Below this index is judged as A-.

[0241] 6. Residual glue performance test

[0242] Stick the protective film tape on the cleaned special test stainless steel plate, compact the tape at each bonding position, and place it in a constant temperature and humidity test box set at 85℃ and 85%. After 24 hours, take out the sample and fully cool it down, tear it open and observe whether there is any residual glue on the steel plate.

[0243] Table 1. Test results of protective film tape in the examples

[0244]

[0245]

[0246] It can be seen from the test results that the water-based low-viscosity acrylic pressure-sensitive adhesive and protective film tape prepared by the present invention have good initial adhesion, low 180° peeling force, good temperature resistance, good later stability, easy to remove after use, and no residual glue phenomenon. The reactive emulsifier system can well improve the initial adhesion and exhaust properties of the protective film tape, and participate in the polymerization reaction to enter the emulsion polyacrylate molecular chain. Compared with the emulsion polyacrylate of the conventional emulsifier system, there is no precipitation of emulsifier in the later stage to affect the physical properties of the product and pollute the surface of the application product, which is more green and environmentally friendly and reduces costs. By comparing the various physical properties and test results of the embodiments of the present invention and the comparative examples, it can be found that obvious differences can be found. The selection and appropriate ratio of acrylic soft monomers, hard monomers and functional monomers have a greater impact on the final physical properties of the protective film product. The initial adhesion, low 180° peeling force, temperature resistance and exhaust properties of a single soft monomer need to be improved. The selection of multiple soft monomers and the appropriate ratio, and then different hard monomers, functional monomers and appropriate ratios and appropriate synthesis processes can further improve the performance of the tape.

[0247] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Water-based low-viscosity acrylic pressure-sensitive adhesive, characterized in that The invention comprises a low-viscosity acrylic ester polymer emulsion, wherein the low-viscosity acrylic ester polymer emulsion is made of raw materials comprising the following components in parts by weight: 39.5 parts of acrylic soft monomer; 2.5-3 parts of acrylic acid functional monomer; 5 parts of hard monomer; Initiator 0.2-1.3 parts; Emulsifier 1.2-3 parts; 0.2 to 1.0 parts of pH stabilizer; 45-55 parts of deionized water; Wherein, the initiator is a redox system initiator, the emulsifier is a reactive emulsifier with an allyl group; the emulsifier is allyl alkyl succinate sulfonate; The acrylic soft monomer is a mixture of butyl acrylate, isooctyl acrylate and lauric acrylate, and the mass ratio of butyl acrylate, isooctyl acrylate and lauric acrylate is 19.5: (10-15): (5-10); The acrylic functional monomer is a mixture of acrylic acid, hydroxyethyl acrylate and β-carboxyethyl acrylic acid, and the mass ratio of acrylic acid, hydroxyethyl acrylate and β-carboxyethyl acrylic acid is 1: (0.5-1): 1; The hard monomer is a mixture of methyl methacrylate and vinyl acetate, and the mass ratio of methyl methacrylate to vinyl acetate is 1:1; The preparation method of the water-based low-viscosity acrylic pressure-sensitive adhesive comprises the following steps: Step 1: Add the first portion of deionized water, the oxidant in the redox system initiator, and the pH stabilizer into the reactor; Step 2: Stir the second part of deionized water and emulsifier to prepare an emulsifier solution; stir the acrylic soft monomer, acrylic functional monomer and hard monomer to prepare a monomer mixed solution; then drop the monomer mixed solution into the emulsifier solution to prepare a monomer emulsion; stir part of the reducing agent in the redox system initiator and the third part of deionized water to prepare a first reducing agent solution for use; Step 3: Start the reaction kettle, stir and heat, and drop the monomer emulsion and the first reducing agent solution into the reaction kettle; keep warm after the dropwise addition is completed, then stir the remaining reducing agent and the remaining deionized water in the redox system initiator to prepare a second reducing agent solution, drop the second reducing agent solution into the reaction kettle, and continue the reaction to obtain a low-viscosity acrylic polymer emulsion.

2. The water-based low-viscosity acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The initiator includes one or more of a hydrogen peroxide-sodium bisulfite system, a persulfate-sodium bisulfite system, and a hydroperoxide-sodium sulfite system; The pH stabilizer is NaHCO3.

3. The water-based low-viscosity acrylic pressure-sensitive adhesive according to claim 1 or 2, characterized in that Also includes neutralizing agents, wetting agents, defoaming agents and curing agents; The mass ratio of the low-viscosity acrylic polymer emulsion, the neutralizer, the wetting agent, the defoamer and the curing agent is 100: (0.5-1.5): (0.1-0.6): (0.05-0.1): (0.5-3.0); The neutralizing agent is a 30% concentration ammonia solution; the wetting agent is a non-ionic wetting agent, and the non-ionic wetting agent includes one or more of polyoxyethylene type, polyol type, alkanolamide type, polyether type, and amine oxide type non-ionic wetting agents; the defoaming agent is a polyester defoaming agent; the curing agent is one or two of a water-based isocyanate curing agent and an aziridine curing agent.

4. The method for preparing the water-based low-viscosity acrylic pressure-sensitive adhesive according to any one of claims 1 to 3, characterized in that The following steps are involved: Step 1: Add the first portion of deionized water, the oxidant in the redox system initiator, and the pH stabilizer into the reactor; Step 2: Stir the second part of deionized water and emulsifier to prepare an emulsifier solution; stir the acrylic soft monomer, acrylic functional monomer and hard monomer to prepare a monomer mixed solution; then drop the monomer mixed solution into the emulsifier solution to prepare a monomer emulsion; stir part of the reducing agent in the redox system initiator and the third part of deionized water to prepare a first reducing agent solution for use; Step 3: Start the reaction kettle, stir and heat, and drop the monomer emulsion and the first reducing agent solution into the reaction kettle; keep warm after the dropwise addition is completed, then stir the remaining reducing agent and the remaining deionized water in the redox system initiator to prepare a second reducing agent solution, drop the second reducing agent solution into the reaction kettle, and continue the reaction to obtain a low-viscosity acrylic polymer emulsion.

5. The method for preparing the water-based low-viscosity acrylic pressure-sensitive adhesive according to claim 4, characterized in that: In step 1, the reactor is a stainless steel reactor equipped with a thermometer, a condenser, a high-level tank and an emulsification tank; In step 2, the stirring speed of the emulsifier solution is 80 to 100 rpm, the stirring time is 20 to 30 minutes, and the stirring is carried out in the emulsification tank; the stirring speed of the monomer mixture is 30 to 60 rpm, the stirring time is 10 to 20 minutes, and the stirring is carried out in the high-level tank when preparing the monomer emulsion; the dropwise addition time of the monomer mixture is 30 to 40 minutes when preparing the monomer emulsion, and the stirring is continued for 40 minutes after the dropwise addition is completed; the stirring of the first reducing agent solution is carried out in the titration tank; In step 3, the reactor is started and heated to 69-71° C., and maintained at the temperature for 15-30 minutes; the monomer emulsion and the first reducing agent solution are dripped into the reactor in two stages, 15% of the monomer emulsion and 15% of the first reducing agent solution are dripped in the first stage, and the dripping rate is controlled so that the time is 50-70 minutes; 85% of the monomer emulsion and 85% of the first reducing agent solution are dripped in the second stage, and the dripping rate is controlled so that the time is 160-200 minutes; the insulation temperature is 69-71° C., and the insulation time is 1-2 hours; the second reducing agent solution is prepared in a titration tank; the second reducing agent solution is dripped into the reactor within 25-45 minutes; the temperature of the continued reaction is 69-71° C., and the time is 3-4 hours; the obtained low-viscosity acrylic polymer emulsion is a milky white emulsion; After step three, the method further includes step four: adding low-viscosity acrylic polymer emulsion, neutralizer, wetting agent, defoamer and curing agent into the glue mixing container in sequence and stirring while adding, and continuing stirring for 15 to 30 minutes after the components are added to obtain a water-based acrylic pressure-sensitive adhesive.

6. A protective film tape, characterized in that The invention comprises a substrate layer and an adhesive layer arranged on the substrate layer, wherein the adhesive layer is made of a water-based low-viscosity acrylic pressure-sensitive adhesive, and the water-based low-viscosity acrylic pressure-sensitive adhesive is the water-based low-viscosity acrylic pressure-sensitive adhesive according to any one of claims 1 to 3 or the water-based low-viscosity acrylic pressure-sensitive adhesive obtained by the preparation method according to claim 4 or 5.

7. The method for preparing the protective film tape according to claim 6, characterized in that include: A water-based low-viscosity acrylic pressure-sensitive adhesive is applied to one side of the substrate layer and then dried.

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