Preparation method of UV (ultraviolet) visbreaking acrylic pressure-sensitive adhesive

Abstract

The invention discloses a preparation method of a UV visbreaking acrylic pressure-sensitive adhesive, and belongs to the field of curing coatings. The preparation method comprises the following steps: respectively reacting an acrylate monomer with an initiator and a solvent to prepare a mixture A and a fluorine-containing mixture B, mixing the mixture A and the fluorine-containing mixture B, adding a cross-linking agent and a photoinitiator, and stirring to prepare the pressure-sensitive adhesive. According to the method, toluene and ethyl acetate are preferably used as solvents, azodiisobutyronitrile is used as an initiator, and N-hydroxymethyl acrylamide and 1-hydroxycyclohexyl phenyl ketone are respectively used as a cross-linking agent and a photoinitiator. The preparation method does not need to add a polyfunctional group diluent, so that the problem of poor compatibility is solved; by optimizing the formula, the initial adhesion is improved, and the residual glue is reduced; the fluorine-containing component endows the adhesive layer with hydrophobicity, and the anti-fouling performance is improved. By reasonably designing the molecular structure and the formula, the problems of poor compatibility, insufficient initial adhesion, insufficient adhesive residue, insufficient surface cleanliness and the like of the existing UV visbreaking acrylic pressure-sensitive adhesive are effectively solved.

Description

Technical Field

[0001] The invention belongs to the field of curing coatings, and particularly relates to a method for preparing a UV viscosity-reducing acrylic pressure-sensitive adhesive. Background Art

[0002] With the rapid development of electronics manufacturing, semiconductor packaging, and other fields, UV-curing adhesives, as an important functional adhesive, have gained widespread application in precision device processing, wafer dicing, and other applications due to their ability to control viscosity through ultraviolet light exposure. Currently, mainstream UV-curing adhesives typically use an acrylate polymer as a base material, compounded with a multifunctional diluent, photoinitiator, and curing agent. While this preparation process meets basic requirements, actual application presents a series of technical bottlenecks that require urgent resolution.

[0003] From the perspective of composition, the multifunctional diluents commonly used in the system have compatibility limitations with the polymer matrix. When the adhesive tape and the object are bonded, the small molecule multifunctional diluent will gradually migrate to the interface, causing the initial viscosity of the adhesive to drop significantly. At the same time, after UV curing and cross-linking, the migration and residue of the multifunctional diluent can easily cause residual adhesive problems.

[0004] In terms of performance, the adhesive tape made of UV adhesive generally has the defect of insufficient initial adhesion. Researchers have improved the initial adhesion performance by reducing the weight-average molecular weight of the adhesive, but this method will weaken the cohesion of the adhesive layer and cause colloid residue during peeling.

[0005] In addition, due to its chemical properties, the surface of the viscosity-reducing acrylic pressure-sensitive adhesive is easily adsorbed by dust particles in the environment, which not only affects the appearance quality of the product, but also poses a potential threat to the performance stability of electronic components.

[0006] In the face of the above technical problems, there is an urgent need to develop a UV-reducing acrylic pressure-sensitive adhesive to solve the problems of poor compatibility, insufficient initial adhesion, residual adhesive and insufficient surface cleanliness of existing UV-reducing acrylic pressure-sensitive adhesives from the aspects of molecular structure design and formula optimization. Summary of the Invention

[0007] Based on the above-mentioned shortcomings of the existing technology, the present invention provides a preparation method of UV viscosity-reducing acrylic pressure-sensitive adhesive, aiming to solve the problems of poor compatibility, insufficient initial adhesion, residual adhesive and insufficient surface cleanliness of the existing UV viscosity-reducing acrylic pressure-sensitive adhesive.

[0008] To achieve the above object, the present invention provides the following technical solutions: A method for preparing a UV-viscosity-reducing acrylic pressure-sensitive adhesive comprises the following steps: S1. 35-45 parts by mass of methyl acrylate, 35-45 parts by mass of butyl acrylate, and 15-25 parts by mass of hydroxyethyl acrylate are mixed and referred to as the total monomers. Then, 25%-40% of the total monomers are added together with 15-25 parts by mass of acrylic acid, 0.04-0.06 parts by mass of initiator, and 180-220 parts by mass of solvent into a reaction vessel. Under a protective atmosphere, the temperature is raised to 70-80° C. and mechanically stirred for reaction for 50-70 minutes. Then, the remaining total monomers are uniformly mixed with 0.1-0.2 parts by mass of initiator, and slowly added dropwise into the reaction vessel under stirring with a mechanical stirrer. After the addition is completed, the temperature is maintained for 3 hours to obtain a mixture A. S2, 35-45 parts by mass of butyl acrylate, 35-45 parts by mass of methyl acrylate, 15-25 parts by mass of acrylic acid, 20-40 parts by mass of perfluorooctyl ethyl acrylate, 0.1-0.2 parts by mass of initiator, and 90-110 parts by mass of solvent are added to a reaction vessel, and under a protective atmosphere, the temperature is raised to 80-90° C., mechanically stirred, and reacted for 2.5-3.5 hours to obtain a fluorine-containing mixture B; S3. Mix 20 to 60 parts by mass of the mixture A described in step S1 with 8 to 12 parts by mass of the fluorinated mixture B described in step S2, stir at a speed of 3500 to 4500 r / min using a high-speed disperser, add 0.8 to 1.2 parts by mass of a cross-linking agent and 0.4 to 0.6 parts by mass of a photoinitiator, and continue stirring at a high speed for 15 to 25 minutes.

[0009] This preparation process features multiple innovative steps. In step S1, the polymer chain length is controlled by adding monomers and initiators in batches. When the initiator is insufficient, the polymerization reaction is terminated, resulting in a polymer with a smaller molecular weight. This results in the synthesis of a lower molecular weight acrylate polymer, which improves the initial tack of the pressure-sensitive adhesive. In step S2, the long-chain fluoroacrylate polymer is obtained by reducing the solvent, increasing the reaction temperature, and directly adding monomers and initiators.

[0010] In step S3, the mixture A and the fluorine-containing mixture B are uniformly mixed by a high-speed disperser to obtain an interlaced network structure, thereby reducing residual glue.

[0011] The mixed colloid is stirred evenly by a high-speed disperser without adding a multifunctional diluent, thus avoiding the problem of poor compatibility between UV viscosity-reducing acrylic pressure-sensitive adhesive and multifunctional diluents.

[0012] Furthermore, the high surface energy of fluoride makes the resulting adhesive highly hydrophobic, increasing the water contact angle of the adhesive layer. When dust accumulates on the adhesive surface, water can be used to wash it away easily, effectively removing it through rolling water droplets. This significantly improves the anti-fouling properties of the UV-resistant acrylic pressure-sensitive adhesive.

[0013] The method is further preferred as a preparation method of UV viscosity-reducing acrylic pressure-sensitive adhesive.

[0014] Preferably, the solvent in step S1 is one of toluene and ethyl acetate.

[0015] Preferably, when the reaction container in step S1 is a four-necked flask, all the feeding ports of the reaction container are sealed, and a mechanical stirring rod is used for stirring. The reaction is carried out for 50 to 70 minutes at a stirring speed of 80 to 100 r / min, followed by insulation for 3 hours, insulation for 0 to 1 hour, stirring at a speed of 80 to 100 r / min, insulation for 1 to 2 hours, stirring at a speed of 140 to 160 r / min, and insulation for 2 to 3 hours at a stirring speed of 180 to 200 r / min.

[0016] The different stirring speeds set in step S1 are: if the stirring speed is too fast at the beginning, the reaction rate will be accelerated and the chain length of the polymer will be increased, so slow stirring is required. As the reaction proceeds, the viscosity of the system becomes larger and larger, and the stirring speed needs to be increased, otherwise the system will easily gel and aggregate.

[0017] Preferably, the stirring speed of the mechanical stirring in step S2 is 250-350 r / min.

[0018] In step S2, the stirring speed needs to be increased from the beginning. Firstly, this is to obtain long-chain polymers. Secondly, the viscosity of the system in step S2 is relatively high, so the stirring speed needs to be increased to avoid gel aggregation.

[0019] Preferably, the initiator in step S1 and step S2 is azobisisobutyronitrile.

[0020] Preferably, the crosslinking agent and the photoinitiator in step S3 are N-hydroxymethyl acrylamide and 1-hydroxycyclohexyl phenyl ketone, respectively.

[0021] Preferably, in step S3, 30 parts by mass of the mixture A described in step S1 are mixed with 10 parts by mass of the fluorine-containing mixture B described in step S2.

[0022] In addition, the present invention provides a UV viscosity-reducing acrylic pressure-sensitive adhesive prepared by the above preparation method.

[0023] The beneficial effects of the present invention compared to the prior art are: (1) The present invention controls the polymer chain length by adding monomers and initiators in batches. When the initiator is insufficient, the polymerization reaction is terminated, resulting in a polymer with a smaller molecular weight, synthesizing a lower molecular weight acrylate polymer, thereby improving the initial tack of the pressure-sensitive adhesive. Furthermore, a fluoroacrylate polymer with a larger molecular weight is synthesized and mixed in a high-speed disperser to form a network structure interlaced with the fluoroacrylate polymer and the acrylate polymer, thereby reducing residual adhesive.

[0024] (2) The present invention stirs the mixed colloid uniformly by a high-speed disperser without adding a multifunctional diluent, thereby avoiding the problem of poor compatibility between UV viscosity-reducing acrylic pressure-sensitive adhesive and multifunctional diluent.

[0025] (3) Fluoride has a high surface energy, which makes the prepared adhesive very hydrophobic and increases the water contact angle of the adhesive layer. When dust is adsorbed on the adhesive surface, it can be washed away by water droplets rolling easily on the surface, which can greatly improve the anti-fouling properties of UV-reduced acrylic pressure-sensitive adhesives.

[0026] (4) By adjusting the formula, the problems of poor compatibility, insufficient initial adhesion, residual adhesive and insufficient surface cleanliness were solved at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The viscosity and initial tack test results of Examples 1 to 7 and Comparative Example 1 are shown; Figure 2 The water contact angles of the UV-viscosity-reducing acrylic pressure-sensitive adhesives prepared in Examples 1 to 7 and Comparative Example 2 were tested by coating them on a PET substrate. DETAILED DESCRIPTION

[0028] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the following embodiments. The following is merely an example and illustration of the concept of the present invention. Those skilled in the art may make various modifications, additions, or substitute similar methods for the specific embodiments described. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

[0029] The above-mentioned preparation method of the present invention is described below through specific examples.

[0030] Example 1 This embodiment provides a method for preparing a UV-viscosity-reducing acrylic pressure-sensitive adhesive, the preparation method comprising the following steps: S1. 40 parts by mass of methyl acrylate, 40 parts by mass of butyl acrylate, and 20 parts by mass of hydroxyethyl acrylate were mixed and referred to as the total monomers. 25% of the total monomers were then added to a reaction vessel together with 20 parts by mass of acrylic acid, 0.05 parts by mass of an initiator, and 200 parts by mass of a solvent. Under a protective atmosphere, the temperature was raised to 75° C. and mechanically stirred for reaction for 1 hour. The remaining total monomers were then uniformly mixed with 0.15 parts by mass of the initiator and slowly added dropwise to the reaction vessel under stirring with a mechanical stirrer. After the addition was completed, the temperature was maintained for 3 hours to obtain a mixture A. S2, 40 parts by mass of butyl acrylate, 40 parts by mass of methyl acrylate, 20 parts by mass of acrylic acid, 20 parts by mass of perfluorooctyl ethyl acrylate, 0.15 parts by mass of initiator and 100 parts by mass of solvent were added to a reaction vessel, and under a protective atmosphere, the temperature was raised to 85° C., mechanically stirred, and reacted for 3 hours to obtain a fluorine-containing mixture B; S3. Mix 20 parts by mass of the mixture A described in step S1 with 10 parts by mass of the fluorinated mixture B described in step S2, stir at a speed of 4000 r / min using a high-speed disperser, add 1 part by mass of a cross-linking agent and 0.5 parts by mass of a photoinitiator, and continue stirring at a high speed for 20 minutes.

[0031] Wherein, the solvent described in step S1 and step S2 is ethyl acetate; When the reaction vessel described in step S1 is a four-necked flask, all the feeding ports of the reaction vessel are sealed, and a mechanical stirring rod is used for stirring. The reaction is carried out for 0 to 1 hour at a stirring speed of 100 r / min, and then kept warm for 3 hours. Within 0 to 1 hour, the stirring speed is 100 r / min, within 1 to 2 hours, the stirring speed is 150 r / min, and within 2 to 3 hours, the stirring speed is 200 r / min; The stirring speed of the mechanical stirring in step S2 is 300 r / min; The initiator in step S1 and step S2 is azobisisobutyronitrile; The crosslinking agent and photoinitiator described in step S3 are N-hydroxymethyl acrylamide and 1-hydroxycyclohexyl phenyl ketone respectively.

[0032] A UV viscosity-reducing acrylic pressure-sensitive adhesive is obtained according to the above preparation method.

[0033] Example 2 This embodiment provides a method for preparing a UV-viscosity-reducing acrylic pressure-sensitive adhesive, the preparation method comprising the following steps: S1. 35 parts by mass of methyl acrylate, 35 parts by mass of butyl acrylate, and 15 parts by mass of hydroxyethyl acrylate were mixed and referred to as the total monomers. 30% of the total monomers were then added to a reaction vessel together with 15 parts by mass of acrylic acid, 0.04 parts by mass of an initiator, and 180 parts by mass of a solvent. Under a protective atmosphere, the temperature was raised to 70° C. and mechanically stirred for reaction for 50 minutes. The remaining total monomers were then uniformly mixed with 0.1 parts by mass of the initiator and slowly added dropwise to the reaction vessel under stirring with a mechanical stirrer. After the addition was completed, the temperature was maintained for 3 hours to obtain a mixture A. S2, 35 parts by mass of butyl acrylate, 35 parts by mass of methyl acrylate, 15 parts by mass of acrylic acid, 30 parts by mass of perfluorooctyl ethyl acrylate, 0.1 parts by mass of initiator and 90 parts by mass of solvent were added to a reaction vessel, and under a protective atmosphere, the temperature was raised to 80° C., mechanically stirred, and reacted for 2.5 hours to obtain a fluorine-containing mixture B; S3. Mix 40 parts by mass of the mixture A described in step S1 with 8 parts by mass of the fluorinated mixture B described in step S2, stir at a speed of 3500 r / min using a high-speed disperser, add 0.8 parts by mass of a cross-linking agent and 0.4 parts by mass of a photoinitiator, and continue stirring at a high speed for 15 minutes.

[0034] Wherein, the solvent described in step S1 and step S2 is toluene; When the reaction vessel in step S1 is a four-necked flask, all the feeding ports of the reaction vessel are sealed, and a mechanical stirring rod is used for stirring. The reaction is carried out for 0 to 1 hour at a stirring speed of 80 r / min, and then the mixture is kept warm for 3 hours. The stirring speed is 80 r / min within 0 to 1 hour, 140 r / min within 1 to 2 hours, and 180 r / min within 2 to 3 hours. The stirring speed of the mechanical stirring in step S2 is 250 r / min; The initiator in step S1 and step S2 is azobisisobutyronitrile; The crosslinking agent and photoinitiator described in step S3 are N-hydroxymethyl acrylamide and 1-hydroxycyclohexyl phenyl ketone respectively.

[0035] A UV viscosity-reducing acrylic pressure-sensitive adhesive is obtained according to the above preparation method.

[0036] Example 3 This embodiment provides a method for preparing a UV-viscosity-reducing acrylic pressure-sensitive adhesive, the preparation method comprising the following steps: S1. 45 parts by mass of methyl acrylate, 45 parts by mass of butyl acrylate, and 25 parts by mass of hydroxyethyl acrylate were mixed and referred to as total monomers. 40% of the total monomers were then added to a reaction vessel together with 25 parts by mass of acrylic acid, 0.06 parts by mass of an initiator, and 220 parts by mass of a solvent. Under a protective atmosphere, the temperature was raised to 80° C. and mechanically stirred for reaction for 70 minutes. The remaining total monomers were then uniformly mixed with 0.2 parts by mass of the initiator and slowly added dropwise to the reaction vessel under stirring with a mechanical stirrer. After the addition was completed, the temperature was maintained for 3 hours to obtain a mixture A. S2, 45 parts by mass of butyl acrylate, 45 parts by mass of methyl acrylate, 25 parts by mass of acrylic acid, 40 parts by mass of perfluorooctyl ethyl acrylate, 0.2 parts by mass of initiator and 110 parts by mass of solvent were added to a reaction vessel, and under a protective atmosphere, the temperature was raised to 90° C., mechanically stirred, and reacted for 3.5 hours to obtain a fluorine-containing mixture B; S3. Mix 60 parts by mass of the mixture A described in step S1 with 12 parts by mass of the fluorinated mixture B described in step S2, stir at a speed of 4500 r / min using a high-speed disperser, add 1.2 parts by mass of a cross-linking agent and 0.6 parts by mass of a photoinitiator, and continue stirring at a high speed for 20 minutes.

[0037] Wherein, the solvent described in step S1 and step S2 is ethyl acetate; When the reaction vessel described in step S1 is a four-necked flask, all the feeding ports of the reaction vessel are sealed, and a mechanical stirring rod is used for stirring. The reaction is carried out for 0 to 1 hour at a stirring speed of 90 r / min, and then the mixture is kept warm for 3 hours. The stirring speed is 90 r / min within 0 to 1 hour, 160 r / min within 1 to 2 hours, and 190 r / min within 2 to 3 hours. The stirring speed of the mechanical stirring in step S2 is 350 r / min; The initiator in step S1 and step S2 is azobisisobutyronitrile; The crosslinking agent and photoinitiator described in step S3 are N-hydroxymethyl acrylamide and 1-hydroxycyclohexyl phenyl ketone respectively.

[0038] A UV viscosity-reducing acrylic pressure-sensitive adhesive is obtained according to the above preparation method.

[0039] Example 4 The difference from Example 1 is that in step S3 , the added amounts of mixture A and fluorine-containing mixture B are 30 parts by mass and 10 parts by mass, respectively.

[0040] Example 5 The difference from Example 1 is that in step S3 , the added amounts of mixture A and fluorine-containing mixture B are 40 parts by mass and 10 parts by mass, respectively.

[0041] Example 6 The difference from Example 1 is that in step S3 , the added amounts of mixture A and fluorine-containing mixture B are 50 parts by mass and 10 parts by mass, respectively.

[0042] Example 7 The difference from Example 1 is that in step S3 , the added amounts of mixture A and fluorine-containing mixture B are 60 parts by mass and 10 parts by mass, respectively.

[0043] Comparative Example 1 The difference from Example 1 is that in step S1, all monomers and initiators are added at once.

[0044] Comparative Example 2 This embodiment provides a method for preparing a UV-viscosity-reducing acrylic pressure-sensitive adhesive, the preparation method comprising the following steps: S1. 40 parts by mass of methyl acrylate, 40 parts by mass of butyl acrylate, and 20 parts by mass of hydroxyethyl acrylate were mixed and referred to as the total monomers. 25% of the total monomers were then added to a reaction vessel together with 20 parts by mass of acrylic acid, 0.05 parts by mass of an initiator, and 200 parts by mass of a solvent. Under a protective atmosphere, the temperature was raised to 75° C. and mechanically stirred for reaction for 1 hour. The remaining total monomers were then uniformly mixed with 0.15 parts by mass of the initiator and slowly added dropwise to the reaction vessel under stirring with a mechanical stirrer. After the addition was completed, the temperature was maintained for 3 hours to obtain a mixture A. S2. Mixture A was stirred at a speed of 4000 r / min using a high-speed disperser, 1 part by mass of a cross-linking agent and 0.5 parts by mass of a photoinitiator were added, and then stirring was continued at a high speed for 20 minutes.

[0045] Wherein, the solvent described in step S1 and step S2 is ethyl acetate; When the reaction vessel described in step S1 is a four-necked flask, all the feeding ports of the reaction vessel are sealed, and a mechanical stirring rod is used for stirring. The reaction is carried out for 0 to 1 hour at a stirring speed of 100 r / min, and then kept warm for 3 hours. Within 0 to 1 hour, the stirring speed is 100 r / min, within 1 to 2 hours, the stirring speed is 150 r / min, and within 2 to 3 hours, the stirring speed is 200 r / min; The initiator in step S1 is azobisisobutyronitrile; The crosslinking agent and photoinitiator described in step S2 are N-hydroxymethyl acrylamide and 1-hydroxycyclohexyl phenyl ketone respectively.

[0046] A UV viscosity-reducing acrylic pressure-sensitive adhesive is obtained according to the above preparation method.

[0047] Comparative Example 3 This comparative example provides a method for preparing a UV viscosity-reducing acrylic pressure-sensitive adhesive by adding a multifunctional diluent, comprising the following steps: S1. 40 parts by mass of methyl acrylate, 40 parts by mass of butyl acrylate, and 20 parts by mass of hydroxyethyl acrylate were mixed and referred to as total monomers. 25% of the total monomers were then added to a reaction vessel together with 20 parts by mass of acrylic acid, 0.05 parts by mass of an initiator, 30 parts by mass of trimethylolpropane triacrylate, and 200 parts by mass of a solvent. Under a protective atmosphere, the temperature was raised to 75° C. and mechanically stirred for reaction for 1 hour. The remaining total monomers were then uniformly mixed with 0.15 parts by mass of the initiator and slowly added dropwise to the reaction vessel under stirring with a mechanical stirrer. After the addition was completed, the temperature was maintained for 3 hours to obtain a mixture A. S2, 40 parts by mass of butyl acrylate, 40 parts by mass of methyl acrylate, 20 parts by mass of acrylic acid, 20 parts by mass of perfluorooctyl ethyl acrylate, 0.15 parts by mass of initiator, 30 parts by mass of trimethylolpropane triacrylate and 100 parts by mass of solvent were added to a reaction vessel, and under a protective atmosphere, the temperature was raised to 85° C., mechanically stirred, and reacted for 3 hours to obtain a fluorine-containing mixture B; S3. Mix 20 parts by mass of the mixture A described in step S1 with 10 parts by mass of the fluorinated mixture B described in step S2, stir at a speed of 4000 r / min using a high-speed disperser, add 1 part by mass of a cross-linking agent and 0.5 parts by mass of a photoinitiator, and continue stirring at a high speed for 20 minutes.

[0048] Wherein, the solvent described in step S1 and step S2 is ethyl acetate; When the reaction vessel described in step S1 is a four-necked flask, all the feeding ports of the reaction vessel are sealed, and a mechanical stirring rod is used for stirring. The reaction is carried out for 0 to 1 hour at a stirring speed of 100 r / min, and then kept warm for 3 hours. Within 0 to 1 hour, the stirring speed is 100 r / min, within 1 to 2 hours, the stirring speed is 150 r / min, and within 2 to 3 hours, the stirring speed is 200 r / min; The stirring speed of the mechanical stirring in step S2 is 300 r / min; The initiator in step S1 and step S2 is azobisisobutyronitrile; The crosslinking agent and photoinitiator described in step S3 are N-hydroxymethyl acrylamide and 1-hydroxycyclohexyl phenyl ketone respectively.

[0049] A UV viscosity-reducing acrylic pressure-sensitive adhesive is obtained according to the above preparation method.

[0050] Comparative Example 4 The difference from Example 1 is that the stirring speed in step S1 is always 100 r / min.

[0051] The mixture A obtained in Comparative Example 4 showed aggregation and gelation.

[0052] Comparative Example 5 The difference from Example 1 is that the stirring speed in step S2 is always 100 r / min.

[0053] The mixture A obtained in Comparative Example 4 showed aggregation and gelation.

[0054] Comparative Example 6 The difference from Example 1 is that in step S3, a high-speed disperser is not used for stirring, and a mechanical rod is used for stirring at a speed of 600 r / min for 20 minutes to prepare a UV viscosity-reducing acrylic pressure-sensitive adhesive.

[0055] Figure 1 The viscosity and initial tack test results for Examples 1-7 and Comparative Example 1 are shown. The viscosity results demonstrate that the present invention controls polymer chain length by adding monomers and initiators in batches. When the initiator is insufficient, the polymerization reaction terminates, resulting in a polymer with a lower molecular weight and synthesizing a lower molecular weight acrylate polymer, thereby improving the initial tack of the pressure-sensitive adhesive. Therefore, the more polymer with a lower molecular weight is added, the greater the initial tack.

[0056] In addition, by comparing the results in Comparative Example 1, it can be seen that the initial adhesion is significantly smaller than that in the embodiment. This is because the monomers and initiators are added together to form long-chain polymers, thereby reducing the initial adhesion.

[0057] Evaluate the residual glue situation according to “no residual glue (√) / slight residual glue (△) / serious residual glue (×)”.

[0058] Table 1 is the residual glue evaluation of Example 1, Comparative Example 2 and Comparative Example 3 sample Example 1 Comparative Example 2 Comparative Example 3 evaluate √ △ × From Table 1, it can be seen that Example 1 has significantly less residual adhesive than Comparative Examples 2 and 3.

[0059] A comparison between Example 1 and Comparative Example 3 demonstrates that the design of a network structure interspersed with fluorinated acrylate polymers and acrylate polymers reduces adhesive residue. Furthermore, the UV-viscosity-reducing acrylic pressure-sensitive adhesive prepared in this invention exhibits both high initial tack and overcomes the adhesive residue problem associated with lower molecular weight acrylate polymers.

[0060] Comparison between Example 1 and Comparative Example 3 shows that the present invention does not add a multifunctional diluent, and the mixed colloid is stirred evenly by a high-speed disperser, thereby solving the problem of poor compatibility between the UV viscosity-reducing acrylic pressure-sensitive adhesive and the multifunctional diluent, which leads to the problem of residual adhesive.

[0061] In addition, the UV viscosity-reducing acrylic pressure-sensitive adhesives prepared in Example 1 and Comparative Example 6 were coated on a PET substrate. After coating the examples, the substrate surface was uniform, while after coating the comparative examples, the coating was uneven. This demonstrates that the present invention achieves uniform colloid mixing using a high-speed disperser without the addition of a multifunctional diluent, whereas the absence of a high-speed disperser results in poor film uniformity. This demonstrates that the high-speed disperser evenly stirs the mixed colloid, eliminating the need for the addition of a multifunctional diluent, thus resolving the issue of poor compatibility between UV-viscosity-reducing acrylic pressure-sensitive adhesive and multifunctional diluents.

[0062] Figure 2 The water contact angles of the UV-viscosity-reducing acrylic pressure-sensitive adhesives prepared in Examples 1-7 and Comparative Example 2 were measured when applied to a PET substrate. As can be seen, the water contact angles in the Examples are significantly greater than those in the Comparative Example, with the water contact angles in Examples 1-7 ranging from 110° to 131°. This demonstrates that the high surface energy of fluoride imparts excellent hydrophobicity to the resulting adhesives, increasing the water contact angle of the adhesive layer. When dust accumulates on the adhesive surface, simply washing with water, where water droplets roll off easily, effectively removes the dust, significantly improving the anti-fouling properties of the UV-viscosity-reducing acrylic pressure-sensitive adhesive.

Claims

1. A method for preparing a UV viscosity-reducing acrylic pressure-sensitive adhesive, characterized in that: The method comprises the following preparation steps: S1. 35-45 parts by mass of methyl acrylate, 35-45 parts by mass of butyl acrylate, and 15-25 parts by mass of hydroxyethyl acrylate are mixed and referred to as the total monomers. Then, 25%-40% of the total monomers are added together with 15-25 parts by mass of acrylic acid, 0.04-0.06 parts by mass of initiator, and 180-220 parts by mass of solvent into a reaction vessel. Under a protective atmosphere, the temperature is raised to 70-80° C. and mechanically stirred for reaction for 50-70 minutes. Then, the remaining total monomers are uniformly mixed with 0.1-0.2 parts by mass of initiator, and slowly added dropwise into the reaction vessel under stirring with a mechanical stirrer. After the addition is completed, the temperature is maintained for 3 hours to obtain a mixture A. S2, 35-45 parts by mass of butyl acrylate, 35-45 parts by mass of methyl acrylate, 15-25 parts by mass of acrylic acid, 20-40 parts by mass of perfluorooctyl ethyl acrylate, 0.1-0.2 parts by mass of initiator, and 90-110 parts by mass of solvent are added to a reaction vessel, and under a protective atmosphere, the temperature is raised to 80-90° C., mechanically stirred, and reacted for 2.5-3.5 hours to obtain a fluorine-containing mixture B; S3. Mix 20 to 60 parts by mass of the mixture A described in step S1 with 8 to 12 parts by mass of the fluorinated mixture B described in step S2, stir at a speed of 3500 to 4500 r / min using a high-speed disperser, add 0.8 to 1.2 parts by mass of a cross-linking agent and 0.4 to 0.6 parts by mass of a photoinitiator, and continue stirring at a high speed for 15 to 25 minutes.

2. The method for preparing the UV viscosity-reducing acrylic pressure-sensitive adhesive according to claim 1, wherein: The solvent in step S1 and step S2 is one of toluene and ethyl acetate.

3. The method for preparing the UV viscosity-reducing acrylic pressure-sensitive adhesive according to claim 1, wherein: When the reaction vessel in step S1 is a four-necked flask, all the feeding ports of the reaction vessel are sealed, and a mechanical stirring rod is used for stirring. The reaction is carried out for 50 to 70 minutes at a stirring speed of 80 to 100 r / min, followed by insulation for 3 hours, insulation for 0 to 1 hour, stirring at a speed of 80 to 100 r / min, insulation for 1 to 2 hours, stirring at a speed of 140 to 160 r / min, and insulation for 2 to 3 hours at a stirring speed of 180 to 200 r / min.

4. The method for preparing the UV viscosity-reducing acrylic pressure-sensitive adhesive according to claim 1, wherein: The stirring speed of the mechanical stirring in step S2 is 250-350 r / min.

5. The method for preparing the UV viscosity-reducing acrylic pressure-sensitive adhesive according to claim 1, wherein: The initiator in step S1 and step S2 is azobisisobutyronitrile.

6. The method for preparing the UV viscosity-reducing acrylic pressure-sensitive adhesive according to claim 1, wherein The crosslinking agent and photoinitiator described in step S3 are N-hydroxymethyl acrylamide and 1-hydroxycyclohexyl phenyl ketone respectively.

7. The method for preparing the UV viscosity-reducing acrylic pressure-sensitive adhesive according to claim 1, wherein: In step S3, 30 parts by mass of the mixture A described in step S1 and 10 parts by mass of the fluorine-containing mixture B described in step S2 are mixed.

8. A UV viscosity-reducing acrylic pressure-sensitive adhesive prepared by the preparation method according to any one of claims 1 to 7.

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