Acrylic emulsion and application thereof, emulsion pressure-sensitive adhesive

Abstract

The invention relates to an acrylic emulsion and an application thereof, and an emulsion pressure-sensitive adhesive, and relates to the technical field of acrylic emulsions. The acrylic emulsion comprises the following raw materials, measured in parts by weight: 70-85 parts of soft monomers, 5-10 parts of hard monomers, 1-3 parts of functional monomers, 0.8-2.0 parts of emulsifiers, 0.3-0.8 parts of pH buffers, 0.2-0.7 parts of initiators, etc. The invention selects a suitable first acrylic ester compound containing a long-chain alkyl group as a soft monomer, a second acrylic ester compound containing an adamantyl group as a hard monomer, and introduces acrylic rosin treated with low-temperature plasma as a functional monomer, so that when the obtained acrylic emulsion is applied to the emulsion pressure-sensitive adhesive, not only the peel strength thereof is significantly improved, but also the phenomenon that the peel force of the pressure-sensitive adhesive increases with time is suppressed, and the use demand for low peel strength growth of the protective film in fields such as electronics and automobiles can be met.

Description

Technical Field

[0001] The invention relates to the technical field of acrylic emulsions, in particular to an acrylic emulsion and application thereof, and an emulsion pressure-sensitive adhesive. Background Art

[0002] As an important polymer material, acrylic emulsion is widely used in coatings, adhesives, textile printing and other fields. Especially in emulsion pressure-sensitive adhesives, its performance directly affects the use effect and life of the product. However, when traditional acrylic emulsions are used in emulsion pressure-sensitive adhesives, there are often some difficult-to-overcome problems.

[0003] On the one hand, the peel strength of traditional acrylic emulsions is difficult to meet the needs of high-end application fields. Peel strength is one of the important indicators for evaluating the performance of pressure-sensitive adhesives. It is directly related to whether the protective film can be stably attached to the protected object during use and can be easily peeled off when needed without leaving residual adhesive or damaging the protected object. However, due to improper monomer selection or unreasonable formula design, traditional acrylic emulsions often result in insufficient peel strength of the resulting pressure-sensitive adhesive, which cannot meet the high requirements for protective films in high-end fields such as electronics and automobiles.

[0004] On the other hand, the pressure-sensitive adhesive made of traditional acrylic emulsion is prone to increase in peeling force after long-term use. This is because the polymer chains in the pressure-sensitive adhesive are prone to rearrangement or cross-linking under the influence of long-term force or environmental factors, resulting in a gradual increase in peeling force. This increase in peeling force will not only affect the use effect of the protective film, but may also cause the protective film to damage the protected object when peeling, or even make it impossible to peel off.

[0005] In order to solve the above problems, researchers have been exploring new acrylic emulsion formulas and preparation processes, among which the selection of monomers is one of the key factors. The types and proportions of soft monomers and hard monomers directly affect the performance of the emulsion, and the introduction of functional monomers can further improve the comprehensive performance of the emulsion. However, the existing acrylic emulsion formula design often finds it difficult to simultaneously meet the requirements of high peel strength and low peel force growth. Summary of the invention

[0006] In order to solve the above problems, the present invention provides an acrylic emulsion and application thereof, and an emulsion pressure-sensitive adhesive.

[0007] In a first aspect, the present invention provides an acrylic emulsion, which comprises the following raw materials in parts by weight: Soft monomer 70-85 parts, hard monomer 5-10 parts, functional monomer 1-3 parts, emulsifier 0.8-2.0 parts, pH buffer 0.3-0.8 parts, initiator 0.2-0.7 parts, defoamer 0.1-0.2 parts, molecular weight regulator 0.1-0.3 parts, pH regulator 0.6-0.9 parts, deionized water 90-110 parts; The soft monomer is a first acrylate compound containing a long-chain alkyl group, and the chemical structural formula of the first acrylate compound is as follows: , R1 is hydrogen or methyl, and R2 is a long-chain alkyl group containing 10 to 14 carbon atoms; The hard monomer is a second acrylic ester compound containing an adamantyl group; The functional monomer is obtained by treating acrylic rosin with low-temperature plasma.

[0008] Furthermore, the acrylic emulsion comprises the following raw materials in parts by weight: 78.5 parts of soft monomer, 7 parts of hard monomer, 2 parts of functional monomer, 1.2 parts of emulsifier, 0.4 parts of pH buffer, 0.5 parts of initiator, 0.12 parts of defoamer, 0.2 parts of molecular weight regulator, 0.7 parts of pH regulator, and 105 parts of deionized water.

[0009] Further, the soft monomer includes at least one of decaacrylate, decamethacrylate, undecyl acrylate, undecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, tetradecyl acrylate and tetradecyl methacrylate.

[0010] Further, the hard monomer includes at least one of 2-methyl-2-adamantyl methacrylate, 1-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate and 2-isopropyl-2-adamantyl methacrylate.

[0011] Furthermore, the preparation method of the functional monomer comprises the following process: The acrylic rosin was placed in the chamber of a low-temperature plasma treatment device and evacuated to below 10 Pa. Then oxygen was introduced at an oxygen flow rate of 45-55 cm 3 The low-temperature plasma treatment is performed for 45 to 75 seconds under the conditions of a flow rate of 100 to 125 W and a power supply of 100 to 125 W to obtain the functional monomer.

[0012] Further, the molecular weight regulator includes n-dodecyl mercaptan, the emulsifier includes at least one of sodium dodecyl diphenyl ether disulfonate and sodium methyl allyl hydroxypropane sulfonate, the initiator includes at least one of potassium persulfate, sodium persulfate and ammonium persulfate, the pH buffer includes at least one of sodium bicarbonate and sodium carbonate, the defoamer includes a mineral oil defoamer, the mineral oil defoamer includes BYK-032 defoamer, and the pH adjuster includes aqueous ammonia.

[0013] Furthermore, the preparation method of the acrylic emulsion comprises the following steps: 0.2-0.7 parts of initiator and 10-15 parts of deionized water are stirred and mixed to obtain an initiator solution; 70-85 parts of soft monomer, 5-10 parts of hard monomer, 1-3 parts of functional monomer, 0.8-2.0 parts of emulsifier, 0.1-0.3 parts of molecular weight regulator and 60-80 parts of deionized water are stirred and mixed to obtain a pre-emulsion; The remaining deionized water and 0.3-0.8 parts of the pH buffer are mixed and heated to 78-82° C., and then an initiator solution accounting for 5-10 wt % of the weight of the initiator solution and a pre-emulsion accounting for 10-15 wt % of the weight of the pre-emulsion are added to react for 25-35 minutes to obtain a seed emulsion; The remaining initiator solution and the remaining pre-emulsion are simultaneously added to the seed emulsion, and the adding time is 3-4 hours; after the pre-emulsion and the initiator solution are simultaneously added, the temperature is raised to 84-86° C. and kept warm for reaction for 1.0-1.5 hours; then when the temperature is lowered to room temperature, 0.6-0.9 parts of a pH regulator and 0.1-0.2 parts of a defoaming agent are sequentially added and stirred for 15-25 minutes to obtain the acrylic emulsion.

[0014] In a second aspect, the present invention provides a use of the acrylic emulsion described in any one of the first aspects in preparing a pressure-sensitive adhesive.

[0015] In a third aspect, the present invention provides an emulsion pressure-sensitive adhesive, wherein the emulsion pressure-sensitive adhesive comprises the acrylic emulsion described in any one of the first aspects.

[0016] The above technical solution provided by the embodiment of the present invention has at least the following advantages compared with the prior art: The embodiment of the present invention provides an acrylic emulsion and its application, and an emulsion pressure-sensitive adhesive. The present invention selects a suitable first acrylic ester compound containing a long-chain alkyl group as a soft monomer, a second acrylic ester compound containing an adamantyl group as a hard monomer, and introduces acrylic rosin treated by low-temperature plasma as a functional monomer, so that when the obtained acrylic emulsion is applied to the emulsion pressure-sensitive adhesive, it not only significantly improves its peel strength, but also inhibits the phenomenon that the peel force of the pressure-sensitive adhesive increases over time, and can meet the use requirements of the fields such as electronics and automobiles for protective films with low peel strength growth. Specifically: 1. The present invention selects the first acrylate compound containing a long-chain alkyl group as a soft monomer, such as acrylate and methacrylate. These soft monomers give the emulsion good flexibility and viscosity, so that the pressure-sensitive adhesive can adapt to the surface morphology of the adherend and improve the peel strength.

[0017] 2. The present invention selects a second acrylate compound containing an adamantyl group as a hard monomer. The adamantyl group is a group with a rigid structure, which can significantly improve the hardness and heat resistance of the polymer, and can balance the excessive flexibility brought by the soft monomer, so that the pressure-sensitive adhesive can maintain high peel strength while also having good cohesive strength and temperature resistance, which helps to resist external force peeling and performance degradation during long-term aging.

[0018] 3. The present invention selects acrylic rosin treated with low-temperature plasma as the functional monomer. Acrylic rosin itself has certain adhesion and tackifying effects. After being treated with low-temperature plasma, its surface properties are improved and more active sites are generated, which promotes the interaction with soft monomers and hard monomers during emulsion polymerization, forming a dense special cross-linking structure, restricting the movement of polymer molecular segments, reducing the rearrangement and relaxation of molecular segments during long-term aging, further improving the peel strength while maintaining the stability of the peel strength, thereby inhibiting the phenomenon that the peel force increases with time.

[0019] In summary, the present invention successfully prepares an acrylic emulsion pressure-sensitive adhesive with excellent performance by selecting a suitable first acrylate compound containing a long-chain alkyl group as a soft monomer, a second acrylate compound containing an adamantyl group as a hard monomer, and introducing acrylic rosin treated with low-temperature plasma as a functional monomer. The pressure-sensitive adhesive not only has a significant peel strength improvement effect, but also can effectively inhibit the phenomenon that the peel force increases with time, so that after aging for 48 hours at 65°C and 95%RH, the 180° peel strength of the pressure-sensitive adhesive is tested according to GB / T 2792-2014, and the peel strength growth rate does not exceed 5%. At the same time, it is observed that the pressure-sensitive adhesive is peeled off from the substrate without residual image and residual adhesive, which can meet the high requirements of the protective film in the fields of electronics and automobiles. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0022] In a first aspect, the present invention provides an acrylic emulsion, which comprises the following raw materials in parts by weight: Soft monomer 70-85 parts, hard monomer 5-10 parts, functional monomer 1-3 parts, emulsifier 0.8-2.0 parts, pH buffer 0.3-0.8 parts, initiator 0.2-0.7 parts, defoamer 0.1-0.2 parts, molecular weight regulator 0.1-0.3 parts, pH regulator 0.6-0.9 parts, deionized water 90-110 parts; The soft monomer is a first acrylate compound containing a long-chain alkyl group, and the chemical structural formula of the first acrylate compound is as follows: , R1 is hydrogen or methyl, and R2 is a long-chain alkyl group containing 10 to 14 carbon atoms; The hard monomer is a second acrylic ester compound containing an adamantyl group; The functional monomer is obtained by treating acrylic rosin with low-temperature plasma.

[0023] An embodiment of the present invention provides an acrylic emulsion. By selecting a suitable first acrylic ester compound containing a long-chain alkyl group as a soft monomer, a second acrylic ester compound containing an adamantyl group as a hard monomer, and introducing acrylic rosin treated by low-temperature plasma as a functional monomer, the obtained acrylic emulsion, when applied to an emulsion pressure-sensitive adhesive, not only significantly improves its peel strength, but also inhibits the phenomenon that the peel force of the pressure-sensitive adhesive increases over time, and can meet the use requirements of the fields such as electronics and automobiles for protective films with low peel strength growth.

[0024] The acrylic rosin in the present invention is also called acrylic modified rosin, which can be prepared by oneself according to the existing process or directly adopted, such as the commercially available acrylic modified rosin (CAS No.: 83137-13-7) of Jiangsu Plus Biotechnology Co., Ltd.

[0025] In some specific embodiments, the acrylic emulsion includes the following raw materials in parts by weight: 78.5 parts of soft monomer, 7 parts of hard monomer, 2 parts of functional monomer, 1.2 parts of emulsifier, 0.4 parts of pH buffer, 0.5 parts of initiator, 0.12 parts of defoamer, 0.2 parts of molecular weight regulator, 0.7 parts of pH regulator, and 105 parts of deionized water.

[0026] In some specific embodiments, the soft monomer includes at least one of deca acrylate, deca methacrylate, undecyl acrylate, undecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, tetradecyl acrylate and tetradecyl methacrylate.

[0027] In some specific embodiments, the hard monomer includes at least one of 2-methyl-2-adamantyl methacrylate, 1-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, and 2-isopropyl-2-adamantyl methacrylate.

[0028] In some specific embodiments, the method for preparing the functional monomer comprises the following process: The acrylic rosin was placed in the chamber of a low-temperature plasma treatment device and evacuated to below 10 Pa. Then oxygen was introduced at an oxygen flow rate of 45-55 cm 3 / min and a power supply of 100-125W, low-temperature plasma treatment is performed for 45-75 seconds to obtain the functional monomer.

[0029] In some specific embodiments, the molecular weight regulator includes n-dodecyl mercaptan, the emulsifier includes at least one of sodium dodecyl diphenyl ether disulfonate and sodium methyl allyl hydroxypropane sulfonate, the initiator includes at least one of potassium persulfate, sodium persulfate and ammonium persulfate, the pH buffer includes at least one of sodium bicarbonate and sodium carbonate, the defoamer includes a mineral oil defoamer, the mineral oil defoamer includes BYK-032 defoamer, and the pH adjuster includes aqueous ammonia, the mass percentage of which is 25%.

[0030] In some specific embodiments, the method for preparing the acrylic emulsion comprises the following steps: 0.2-0.7 parts of initiator and 10-15 parts of deionized water are stirred and mixed to obtain an initiator solution; 70-85 parts of soft monomer, 5-10 parts of hard monomer, 1-3 parts of functional monomer, 0.8-2.0 parts of emulsifier, 0.1-0.3 parts of molecular weight regulator and 60-80 parts of deionized water are stirred and mixed to obtain a pre-emulsion; The remaining deionized water and 0.3-0.8 parts of the pH buffer are mixed and heated to 78-82° C., and then an initiator solution accounting for 5-10 wt % of the weight of the initiator solution and a pre-emulsion accounting for 10-15 wt % of the weight of the pre-emulsion are added to react for 25-35 minutes to obtain a seed emulsion; The remaining initiator solution and the remaining pre-emulsion are simultaneously added to the seed emulsion, and the adding time is 3-4 hours; after the pre-emulsion and the initiator solution are simultaneously added, the temperature is raised to 84-86° C. and kept warm for reaction for 1.0-1.5 hours; then when the temperature is lowered to room temperature, 0.6-0.9 parts of a pH regulator and 0.1-0.2 parts of a defoaming agent are sequentially added and stirred for 15-25 minutes to obtain the acrylic emulsion.

[0031] The preparation method of the acrylic emulsion provided by the embodiment of the present invention is simple to operate and suitable for batch industrial production.

[0032] In a second aspect, based on the same inventive concept, the present invention provides a use of the acrylic emulsion described in any one of the first aspects in the preparation of a pressure-sensitive adhesive.

[0033] When the acrylic emulsion provided by the present invention is applied to an emulsion pressure-sensitive adhesive, not only the peel strength thereof is significantly improved, but also the phenomenon that the peel force of the pressure-sensitive adhesive increases with time is suppressed, and the use demand for protective films with low peel strength growth in fields such as electronics and automobiles can be met.

[0034] In a third aspect, based on the same inventive concept, the present invention provides an emulsion pressure-sensitive adhesive, wherein the emulsion pressure-sensitive adhesive comprises the acrylic emulsion described in any one of the first aspects.

[0035] The emulsion pressure-sensitive adhesive provided by the present invention is realized based on the acrylic emulsion described in any one of the first aspects, and therefore has at least the beneficial effects of the acrylic emulsion described in any one of the first aspects, which will not be described in detail here.

[0036] It should be noted that the components and raw materials involved in the acrylic emulsion and its application, and the emulsion pressure-sensitive adhesive provided in the embodiments of the present invention, unless otherwise specified or specified, can be directly commercially available products or homemade using existing public preparation methods; at the same time, the steps and parameters involved, unless otherwise specified or specified, can be carried out according to the existing processing technology of acrylic emulsions and emulsion pressure-sensitive adhesives or directly carried out using existing equipment, and the present invention document will not elaborate on them one by one.

[0037] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0038] The main raw material information involved in the following examples and comparative examples is as follows: The CAS number of acrylic rosin is 83137-13-7; the CAS number of acrylate decadecyl is 1330-61-6; the CAS number of methacrylate dodecyl is 142-90-5; the CAS number of acrylate tetradecyl is 21643-42-5; the CAS number of 2-methyl-2-adamantyl methacrylate is 177080-67-0; the CAS number of 1-adamantyl methacrylate is 16887-36-8; the CAS number of 2-isopropyl-2-adamantyl methacrylate is 297156-50-4; the CAS number of butyl acrylate is 141-32-2; and the CAS number of isobornyl methacrylate is 7534-94-3.

[0039] Example 1: This example provides an acrylic emulsion, which includes the following raw materials in parts by weight: 78.5 parts of soft monomer, 7 parts of hard monomer, 2 parts of functional monomer, 1.2 parts of emulsifier, 0.4 parts of pH buffer, 0.5 parts of initiator, 0.12 parts of defoamer, 0.2 parts of molecular weight regulator, 0.7 parts of pH regulator, 105 parts of deionized water; The soft monomer is dodecyl methacrylate; The hard monomer is 1-adamantyl methacrylate; The functional monomer is obtained by treating acrylic rosin with low-temperature plasma. The preparation method of the functional monomer comprises the following steps: placing the acrylic rosin in a cavity of a low-temperature plasma treatment device and evacuating the cavity to below 10 Pa, then introducing oxygen at an oxygen flow rate of 50 cm 3 / min and a power supply of 115W, and subjected to low-temperature plasma treatment for 60 seconds to obtain the functional monomer; The emulsifier is sodium dodecyl diphenyl ether disulfonate; The pH buffer is sodium carbonate; The initiator is potassium persulfate; The defoamer is BYK-032 defoamer; The molecular weight regulator is n-dodecyl mercaptan; The pH regulator is aqueous ammonia.

[0040] The preparation method of the acrylic emulsion comprises the following steps: 0.5 parts of initiator and 12 parts of deionized water were stirred and mixed to obtain an initiator solution; 78.5 parts of soft monomer, 7 parts of hard monomer, 2 parts of functional monomer, 1.2 parts of emulsifier, 0.2 parts of molecular weight regulator and 70 parts of deionized water were stirred and mixed to obtain a pre-emulsion; The remaining deionized water and 0.4 parts of the pH buffer are mixed and heated to 80.5° C., and then an initiator solution accounting for 7 wt % of the weight of the initiator solution and a pre-emulsion accounting for 12 wt % of the weight of the pre-emulsion are added to react for 30 minutes to obtain a seed emulsion; The remaining initiator solution and the remaining pre-emulsion are simultaneously added to the seed emulsion, and the adding time is 3.5 hours; after the pre-emulsion and the initiator solution are simultaneously added, the temperature is raised to 86° C. and kept warm for reaction for 1 hour; then when the temperature is lowered to room temperature, 0.7 parts of a pH regulator and 0.12 parts of a defoaming agent are added in sequence and stirred for 20 minutes to obtain the acrylic emulsion.

[0041] Example 2: This example provides an acrylic emulsion, which includes the following raw materials in parts by weight: 70 parts of soft monomer, 5 parts of hard monomer, 1 part of functional monomer, 0.8 parts of emulsifier, 0.3 parts of pH buffer, 0.2 parts of initiator, 0.1 parts of defoamer, 0.1 parts of molecular weight regulator, 0.6 parts of pH regulator, 90 parts of deionized water; The soft monomer is acrylate; The hard monomer is 2-methyl-2-adamantyl methacrylate; The functional monomer is obtained by treating acrylic rosin with low-temperature plasma. The preparation method of the functional monomer comprises the following steps: placing the acrylic rosin in a low-temperature plasma treatment device cavity and evacuating the cavity to below 10 Pa, then introducing oxygen at an oxygen flow rate of 55 cm 3 / min and a power supply of 100 W, performing low-temperature plasma treatment for 75 seconds to obtain the functional monomer; The emulsifier is sodium methyl allyl hydroxypropane sulfonate; The pH buffer is sodium bicarbonate; The initiator is sodium persulfate; The defoamer is BYK-032 defoamer; The molecular weight regulator is n-dodecyl mercaptan; The pH regulator is aqueous ammonia.

[0042] The preparation method of the acrylic emulsion comprises the following steps: 0.2 parts of initiator and 10 parts of deionized water were stirred and mixed to obtain an initiator solution; 70 parts of soft monomer, 5 parts of hard monomer, 1 part of functional monomer, 0.8 parts of emulsifier, 0.1 parts of molecular weight regulator and 60 parts of deionized water were stirred and mixed to obtain a pre-emulsion; The remaining deionized water and 0.3 parts of the pH buffer are mixed and heated to 78° C., and then an initiator solution accounting for 5 wt % of the weight of the initiator solution and a pre-emulsion accounting for 10 wt % of the weight of the pre-emulsion are added to react for 35 minutes to obtain a seed emulsion; The remaining initiator solution and the remaining pre-emulsion are simultaneously added to the seed emulsion, and the dropping time is 3 hours; after the pre-emulsion and the initiator solution are simultaneously added, the temperature is raised to 84° C. and kept warm for reaction for 1 hour; then when the temperature is lowered to room temperature, 0.6 parts of pH regulator and 0.1 parts of defoaming agent are added in sequence and stirred for 15 minutes to obtain the acrylic emulsion.

[0043] Example 3: This example provides an acrylic emulsion, which includes the following raw materials in parts by weight: 85 parts of soft monomer, 10 parts of hard monomer, 3 parts of functional monomer, 2.0 parts of emulsifier, 0.8 parts of pH buffer, 0.7 parts of initiator, 0.2 parts of defoamer, 0.3 parts of molecular weight regulator, 0.9 parts of pH regulator, 110 parts of deionized water; The soft monomer is tetradecyl acrylate; The hard monomer is 2-isopropyl-2-adamantyl methacrylate; The functional monomer is obtained by treating acrylic rosin with low-temperature plasma. The preparation method of the functional monomer includes the following steps: placing the acrylic rosin in a low-temperature plasma treatment device cavity and evacuating the cavity to below 10 Pa, then introducing oxygen at an oxygen flow rate of 45 cm 3 / min and a power supply of 125W, performing low-temperature plasma treatment for 45 seconds to obtain the functional monomer; The emulsifier is sodium methyl allyl hydroxypropane sulfonate; The pH buffer is sodium carbonate; The initiator is ammonium persulfate; The defoamer is BYK-032 defoamer; The molecular weight regulator is n-dodecyl mercaptan; The pH regulator is aqueous ammonia.

[0044] The preparation method of the acrylic emulsion comprises the following steps: 0.7 parts of initiator and 15 parts of deionized water were stirred and mixed to obtain an initiator solution; 85 parts of soft monomer, 10 parts of hard monomer, 3 parts of functional monomer, 2.0 parts of emulsifier, 0.3 parts of molecular weight regulator and 80 parts of deionized water were stirred and mixed to obtain a pre-emulsion; The remaining deionized water and 0.8 parts of the pH buffer are mixed and heated to 82° C., and then an initiator solution accounting for 10 wt % of the weight of the initiator solution and a pre-emulsion accounting for 15 wt % of the weight of the pre-emulsion are added to react for 25 minutes to obtain a seed emulsion; The remaining initiator solution and the remaining pre-emulsion are simultaneously added to the seed emulsion, and the dropping time is 4 hours; after the pre-emulsion and the initiator solution are simultaneously added, the temperature is raised to 86° C. and kept warm for reaction for 1 hour; then when the temperature is lowered to room temperature, 0.9 parts of a pH adjuster and 0.2 parts of a defoaming agent are added in sequence and stirred for 25 minutes to obtain the acrylic emulsion.

[0045] Comparative Example 1 This example provides an acrylic emulsion and a preparation method thereof, which is different from Example 1 only in that the soft monomer is adjusted to butyl acrylate; the remaining steps and parameters are the same.

[0046] Comparative Example 2 This example provides an acrylic emulsion and a preparation method thereof, which is different from Example 1 only in that the hard monomer is adjusted to isobornyl methacrylate; the remaining steps and parameters are the same.

[0047] Comparative Example 3 This example provides an acrylic emulsion and a preparation method thereof, which is different from Example 1 only in that the functional monomer is acrylic rosin (not treated with low-temperature plasma); the remaining steps and parameters are the same.

[0048] Test Case In this example, the acrylic emulsions obtained in the above Examples 1 to 3 and Comparative Examples 1 to 3 were used to prepare pressure-sensitive adhesive tapes for performance testing.

[0049] Test method: 1) The acrylic emulsions obtained in the above examples 1 to 3 and comparative examples 1 to 3 were respectively coated on the corona surface of the polyethylene substrate as an emulsion pressure-sensitive adhesive, with a film thickness of 10 μm, and placed in a 95°C oven for baking for 8 minutes to obtain the pressure-sensitive adhesive tape sample to be tested. 2) The 180° peel strength (M1, unit: N / 25mm) of the pressure-sensitive adhesive sample was tested in accordance with GB / T 2792-2014, and the test results are shown in Table 1. 3) After aging for 48 hours at 65°C and 95% RH, the 180° peel strength (M2, unit: N / 25mm) of the pressure-sensitive adhesive sample after accelerated aging was tested in accordance with GB / T 2792-2014, and the peel strength growth rate (%) was calculated according to the formula: Peel strength growth rate (%) = (M2-M1) / M1×100%, and the test results are shown in Table 2.

[0050] Table 1 Test samples 180° peel strength, M1 (N / 25mm) Example 1 18.2 Example 2 15.6 Example 3 16.8 Comparative Example 1 9.3 Comparative Example 2 10.7 Comparative Example 3 12.0 Table 2 Test samples Peel strength growth rate (%) Example 1 2.6 Example 2 4.5 Example 3 3.3 Comparative Example 1 11.8 Comparative Example 2 17.9 Comparative Example 3 15.1 It can be seen from Table 1 and Table 2 that, compared with Comparative Examples 1 to 3, the acrylic emulsion provided in the embodiment of the present invention has higher peel strength when applied to the emulsion pressure-sensitive adhesive to prepare the pressure-sensitive adhesive tape, and can effectively inhibit the phenomenon that the peel force of the pressure-sensitive adhesive increases over time. After aging for 48 hours at 65°C and 95%RH, the 180° peel strength of the pressure-sensitive adhesive is tested in accordance with GB / T 2792-2014, and the peel strength growth rate does not exceed 5%. At the same time, it is observed that there is no afterimage or residual adhesive after the pressure-sensitive adhesive is peeled off from the substrate, which can meet the high requirements of the electronics, automobile and other fields for protective films.

[0051] In summary, the embodiments of the present invention provide an acrylic emulsion and its application, and an emulsion pressure-sensitive adhesive. The present invention selects a suitable first acrylic ester compound containing a long-chain alkyl group as a soft monomer, a second acrylic ester compound containing an adamantyl group as a hard monomer, and introduces acrylic rosin treated with low-temperature plasma as a functional monomer. When the obtained acrylic emulsion is applied to the emulsion pressure-sensitive adhesive, not only its peel strength is significantly improved, but also the phenomenon that the peel force of the pressure-sensitive adhesive increases with time is suppressed, and the use requirements of the protective film with low peel strength growth in the fields such as electronics and automobiles can be met.

[0052] Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0053] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An acrylic emulsion, characterized in that: The acrylic emulsion comprises the following raw materials in parts by weight: Soft monomer 70-85 parts, hard monomer 5-10 parts, functional monomer 1-3 parts, emulsifier 0.8-2.0 parts, pH buffer 0.3-0.8 parts, initiator 0.2-0.7 parts, defoamer 0.1-0.2 parts, molecular weight regulator 0.1-0.3 parts, pH regulator 0.6-0.9 parts, deionized water 90-110 parts; The soft monomer is a first acrylate compound containing a long-chain alkyl group, and the chemical structural formula of the first acrylate compound is as follows: , R1 is hydrogen or methyl, and R2 is a long-chain alkyl group containing 10 to 14 carbon atoms; The hard monomer is a second acrylic ester compound containing an adamantyl group; The functional monomer is obtained by treating acrylic rosin with low-temperature plasma.

2. The acrylic emulsion according to claim 1, characterized in that The acrylic emulsion comprises the following raw materials in parts by weight: 78.5 parts of soft monomer, 7 parts of hard monomer, 2 parts of functional monomer, 1.2 parts of emulsifier, 0.4 parts of pH buffer, 0.5 parts of initiator, 0.12 parts of defoamer, 0.2 parts of molecular weight regulator, 0.7 parts of pH regulator, and 105 parts of deionized water.

3. The acrylic emulsion according to claim 1, characterized in that The soft monomer includes at least one of decaacrylate, decamethacrylate, undecyl acrylate, undecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, tetradecyl acrylate and tetradecyl methacrylate.

4. The acrylic emulsion according to claim 1, characterized in that The hard monomer includes at least one of 2-methyl-2-adamantyl methacrylate, 1-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, and 2-isopropyl-2-adamantyl methacrylate.

5. The acrylic emulsion according to claim 1, characterized in that The preparation method of the functional monomer comprises the following steps: The acrylic rosin was placed in the chamber of a low-temperature plasma treatment device and evacuated to below 10 Pa. Then oxygen was introduced at an oxygen flow rate of 45-55 cm 3 The low-temperature plasma treatment is performed for 45 to 75 seconds under the conditions of a flow rate of 100 to 125 W and a power supply of 100 to 125 W to obtain the functional monomer.

6. The acrylic emulsion according to claim 1, characterized in that The molecular weight regulator includes n-dodecyl mercaptan, the emulsifier includes at least one of sodium dodecyl diphenyl ether disulfonate and sodium methyl allyl hydroxypropane sulfonate, the initiator includes at least one of potassium persulfate, sodium persulfate and ammonium persulfate, the pH buffer includes at least one of sodium bicarbonate and sodium carbonate, the defoamer includes a mineral oil defoamer, the mineral oil defoamer includes BYK-032 defoamer, and the pH adjuster includes aqueous ammonia.

7. The acrylic emulsion according to any one of claims 1 to 6, characterized in that The preparation method of the acrylic emulsion comprises the following steps: 0.2-0.7 parts of initiator and 10-15 parts of deionized water are stirred and mixed to obtain an initiator solution; 70-85 parts of soft monomer, 5-10 parts of hard monomer, 1-3 parts of functional monomer, 0.8-2.0 parts of emulsifier, 0.1-0.3 parts of molecular weight regulator and 60-80 parts of deionized water are stirred and mixed to obtain a pre-emulsion; The remaining deionized water and 0.3-0.8 parts of the pH buffer are mixed and heated to 78-82° C., and then an initiator solution accounting for 5-10 wt % of the weight of the initiator solution and a pre-emulsion accounting for 10-15 wt % of the weight of the pre-emulsion are added to react for 25-35 minutes to obtain a seed emulsion; The remaining initiator solution and the remaining pre-emulsion are simultaneously added to the seed emulsion, and the adding time is 3-4 hours; after the pre-emulsion and the initiator solution are simultaneously added, the temperature is raised to 84-86° C. and kept warm for reaction for 1.0-1.5 hours; then when the temperature is lowered to room temperature, 0.6-0.9 parts of a pH regulator and 0.1-0.2 parts of a defoaming agent are sequentially added and stirred for 15-25 minutes to obtain the acrylic emulsion.

8. Use of the acrylic emulsion according to any one of claims 1 to 7 in the preparation of a pressure-sensitive adhesive.

9. An emulsion pressure-sensitive adhesive, characterized in that: The emulsion pressure-sensitive adhesive comprises the acrylic emulsion according to any one of claims 1 to 7.

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