Ultraviolet curing pressure-sensitive adhesive, adhesive tape, preparation method and application

Abstract

The invention relates to an ultraviolet curing pressure-sensitive adhesive, an adhesive tape, a preparation method and application, and the ultraviolet curing pressure-sensitive adhesive comprises the following components in parts by weight: 100 parts of a prepolymer, 0.08-0.12 part of a cross-linking agent, 0.05-0.12 part of a first photoinitiator and 1.5-2.0 parts of fumed silica, wherein the prepolymer is formed by polymerizing acrylic acid, acrylic acid-2-ethylhexyl ester and 2-ethylhexyl acrylate in the presence of a second photoinitiator, the mass ratio of the acrylic acid to the acrylic acid-2-ethylhexyl ester to the 2-ethylhexyl acrylate is (9.5-9.9): (55.1-56.5): (34.0-35.0), and the second photoinitiator accounts for 0.03%-0.05% of the total mass of the acrylic acid, the acrylic acid-2-ethylhexyl ester and the 2-ethylhexyl acrylate; and the viscosity of the prepolymer is 1000 + / -200 mPa * s. The pressure-sensitive adhesive has good bonding performance on ABS (Acrylonitrile Butadiene Styrene) and organism nails.

Description

Technical Field

[0001] This invention relates to the field of adhesives, specifically to a UV-curable pressure-sensitive adhesive, tape, preparation method, and application. Background Technology

[0002] Pressure-sensitive adhesives (PSA) are adhesives that develop tack under slight pressure and adhere firmly to various material surfaces. Traditional PSAs (such as solvent-based and emulsion-based adhesives based on natural rubber or acrylates) often have limitations in bonding to non-polar plastics (such as ABS) and special biological surfaces (such as human nails). For ABS sheets, the low surface energy and potential presence of trace amounts of plasticizer or release agent migration make it difficult for many adhesives to achieve strong and durable bonds. For human nails, the surface is a hydrophobic, smooth, and hard curved surface composed of keratin; conventional adhesives either lack sufficient tack and are prone to detachment, or contain irritating chemicals unsuitable for skin contact. Currently, there is a lack of PSA products that simultaneously possess ultra-high tack to both ABS engineering plastics and human nails, along with comprehensive properties such as rapid curing, environmental friendliness, and non-irritating safety. Ultraviolet (UV) curing technology offers a potential solution, but its formulation design is crucial.

[0003] Pressure-sensitive adhesives (PSA) are adhesives that develop tack under slight pressure and adhere firmly to various material surfaces. Traditional PSAs (such as solvent-based and emulsion-based adhesives based on natural rubber or acrylates) often have limitations in bonding to non-polar plastics (such as ABS) and special biological surfaces (such as human nails). For ABS sheets, the low surface energy and potential presence of trace amounts of plasticizer or release agent migration make it difficult for many adhesives to achieve strong and durable bonds. For human nails, the surface is a hydrophobic, smooth, and hard curved surface composed of keratin; conventional adhesives either lack sufficient tack and are prone to detachment, or contain irritating chemicals unsuitable for skin contact. Currently, there is a lack of PSA products that simultaneously possess ultra-high tack to both ABS engineering plastics and human nails, along with comprehensive properties such as rapid curing, environmental friendliness, and non-irritating safety. Ultraviolet (UV) curing technology offers a potential solution, but its formulation design is crucial. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the primary objective of this invention is to provide a UV-curable pressure-sensitive adhesive that exhibits excellent adhesion to both ABS and biological nails.

[0005] A second objective of this invention is to provide a method for preparing the UV-curable pressure-sensitive adhesive.

[0006] A third objective of this invention is to provide a tape prepared from the UV-curable pressure-sensitive adhesive.

[0007] A fourth objective of this invention is to provide a method for preparing the tape.

[0008] A fifth objective of this invention is to provide applications of the pressure-sensitive adhesive or tape.

[0009] To achieve the first objective of this invention, this invention provides a UV-curable pressure-sensitive adhesive, comprising the following components by weight: 100 parts of prepolymer, 0.08 to 0.12 parts of crosslinking agent, 0.05 to 0.12 parts of first photoinitiator, and 1.5 to 2.0 parts of fumed silica; wherein the prepolymer is polymerized from acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate under a second photoinitiator, the mass ratio of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate is (9.5 to 9.9):(55.1 to 56.5):(34.0 to 35.0), and the second photoinitiator accounts for 0.03% to 0.05% of the total mass of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate; the viscosity of the prepolymer is 1000 ± 200 mPa·s; and one molecule of the crosslinking agent has at least two alkenyl groups.

[0010] In some embodiments of the present invention, the mass ratio of acrylic acid, 2-ethylhexyl acrylate and isooctyl acrylate in the prepolymer is (9.5~9.7):(55.7~56.5):(34.0~34.6).

[0011] In some embodiments of the present invention, the second photoinitiator accounts for 0.04% of the total mass of acrylic acid, 2-ethylhexyl acrylate and isooctyl acrylate.

[0012] In some embodiments of the present invention, the amount of crosslinking agent is 0.08 to 0.1 parts relative to 100 parts of the prepolymer.

[0013] In some embodiments of the present invention, the fumed silica is hydrophobic fumed silica with an average particle size of 10 nm to 30 nm and a specific surface area of ​​80 m² / g to 150 m² / g.

[0014] In some embodiments of the present invention, the crosslinking agent is selected from at least one of 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, 1,3-butanediol diacrylate, and diethylene glycol diacrylate.

[0015] In some embodiments of the present invention, the first photoinitiator and the second photoinitiator are each independently selected from at least one of 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0016] To achieve the second objective of this invention, this invention provides a method for preparing a UV-curable pressure-sensitive adhesive as described in any of the above-mentioned embodiments, comprising the following steps: Step 1: In a reaction environment protected from light and by an inert gas, accurately weigh acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate monomers, add a second photoinitiator, and stir and mix at a speed of 300 rpm to 500 rpm for 25 to 30 minutes to ensure that the initiator is completely dissolved and the mixture is uniform; then, under continuous stirring, irradiate the reaction system with UV light at an irradiation intensity of 3 mW / cm² to 6 mW / cm², with the irradiation time controlled at 1 to 2 minutes. Measure the viscosity of the prepolymer mixture by online monitoring or sampling. When the viscosity rises to 1000 ± 200 mPa·s, stop the irradiation to obtain the prepolymer; Step 2: Add a first photoinitiator, a crosslinking agent, and nano-fumed silica to the prepolymer, and initially mix at a stirring speed of 300 rpm to 500 rpm for 5 to 10 minutes, then increase the stirring speed to 1500 rpm. High-speed shear dispersion is performed at rpm~2000 rpm for 30 to 45 minutes to form a uniform, fine paste without visible particles or agglomerates; Step 3: The obtained paste is transferred to a vacuum degassing device and degassed for 15 to 30 minutes at a vacuum of -0.095 MPa to -0.1 MPa to obtain pressure-sensitive adhesive.

[0017] In some embodiments of the present invention, step one and step two are carried out in a transparent reaction vessel.

[0018] In some embodiments of the present invention, the dominant wavelength of the ultraviolet light in step one is 365 nm.

[0019] In some embodiments of the present invention, the inert gas is nitrogen or argon; In some embodiments of the present invention, the vacuum degassing device is a vacuum planetary mixer or a vacuum dryer.

[0020] To achieve the third objective of the present invention, the present invention provides an adhesive tape comprising a release film and an adhesive layer disposed on the release film, the adhesive layer being made of pressure-sensitive adhesive as described in any of the above embodiments.

[0021] To achieve the fourth objective of this invention, this invention provides a method for preparing the above-mentioned adhesive tape, comprising the following steps: applying the pressure-sensitive adhesive to the release film by means of scraping or die coating to form a wet adhesive layer with a thickness of 300 micrometers to 500 micrometers, and then curing it under ultraviolet light with an energy of 800 mJ / cm² to 1200 mJ / cm² to form an adhesive layer.

[0022] To achieve the fifth objective of this invention, this invention provides an adhesive composite structure, comprising an object to be bonded and an adhesive layer bonded to the surface of the object; the object to be bonded is a low surface energy plastic or a biological fingernail, wherein the low surface energy plastic is ABS, PE, PP or PS; and the adhesive layer is a pressure-sensitive adhesive or tape as described in any of the above embodiments.

[0023] Compared with the prior art, the present invention can achieve the following beneficial effects: The pressure-sensitive adhesive and the resulting tape of this invention utilize a specific amount of acrylic monomer in the prepolymer to provide strongly polar adhesive groups, forming a strong interaction with low surface energy plastics such as ABS and nail surfaces; 2-ethylhexyl acrylate and isooctyl acrylate provide flexible long chains, enhancing wettability and viscoelasticity; extremely low amounts of crosslinking agents achieve "micro-crosslinking," improving cohesion without sacrificing tack; nano-fumed silica is used as a physical crosslinking point and thixotropic agent, enhancing modulus and holding power; simultaneously, a low dose of photoinitiator ensures complete curing and no residue. The resulting pressure-sensitive adhesive and the resulting tape exhibit high adhesion to low surface energy plastics such as ABS and biological nails, with a peel strength ≥30 N / 25 mm for ABS and "lock-in" adhesion to nails; excellent tack / cohesion balance, no residue after peeling, and long holding time; safe and non-irritating, using low initiator dosage, high conversion rate, suitable for skin contact; good processability, easy to coat, fast curing, suitable for continuous production; precise component dosage, stable performance, and optimized raw material costs. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the preparation process of the UV-curable pressure-sensitive adhesive tape of the present invention.

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0026] This invention provides a UV-curable pressure-sensitive adhesive that exhibits excellent adhesion to non-polar plastics (such as ABS, PP, PE, and PS) and hydrophobic surfaces of biological materials (such as human fingernails). It overcomes the problems of traditional pressure-sensitive adhesives' weak and short-lasting adhesion to low surface energy plastics or fingernails, while also avoiding skin irritation from harsh chemicals. This UV-curable pressure-sensitive adhesive simultaneously provides ultra-high adhesion to both ABS engineering plastics and human fingernails, and possesses comprehensive properties such as rapid curing, environmental friendliness, and safety with no irritation. Of course, this UV-curable pressure-sensitive adhesive can also be used for bonding in other fields and on other items.

[0027] Specifically, the UV-curable pressure-sensitive adhesive of this embodiment contains the following components by weight: 100 parts of prepolymer, 0.08 to 0.12 parts of crosslinking agent, 0.05 to 0.12 parts of first photoinitiator, and 1.5 to 2.0 parts of fumed silica.

[0028] Among them, the prepolymer is the product obtained by prepolymerization, which is between the monomer and the final polymer, and the active groups are retained at the ends of the molecular chains.

[0029] The prepolymer is polymerized from acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate under a second photoinitiator. The mass ratio of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate is (9.5~9.9):(55.1~56.5):(34.0~35.0). For example, with a total mass of 100 parts of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate, the amount of acrylic acid can be 9.5 parts to 9.9 parts, such as 9.5 parts, 9.6 parts, 9.7 parts, 9.8 parts, 9.9 parts, etc.; the amount of 2-ethylhexyl acrylate can be 55.1 parts to 56.5 parts, such as 55. The dosages are 1 part, 55.2 parts, 55.3 parts, 55.4 parts, 55.5 parts, 55.6 parts, 55.7 parts, 55.8 parts, 55.9 parts, 56 parts, 56.1 parts, 56.2 parts, 56.3 parts, 56.4 parts, 56.5 parts, etc.; the dosage of isooctyl acrylate can be 34.0 parts to 35.0 parts, for example, 34 parts, 34.1 parts, 34.2 parts, 34.3 parts, 34.4 parts, 34.5 parts, 34.6 parts, 34.7 parts, 34.8 parts, 34.9 parts, 35 parts, etc. Acrylic acid can provide strong polar adhesive groups, forming a strong interaction with ABS and nail surfaces; 2-ethylhexyl acrylate and isooctyl acrylate provide flexible long chains, enhancing wettability and viscoelasticity. The combination of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate in the above-mentioned proportions can better balance the adhesion, wetting, and viscoelasticity of the pressure-sensitive adhesive. The second photoinitiator accounts for 0.03% to 0.05% of the total mass of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate, for example, 0.03%, 0.04%, or 0.05%. That is, relative to 100 parts of prepolymer, the second photoinitiator can be 0.03 to 0.05 parts, for example, 0.03 parts, 0.04 parts, or 0.05 parts. Using a small amount of the second photoinitiator helps reduce residual photoinitiator, avoiding irritation to the human body, and also helps control the polymerization reaction of the prepolymer.

[0030] The viscosity of the prepolymer is 1000±200 mPa·s. Within this viscosity range, the prepolymer effectively reduces the final curing shrinkage stress and optimizes the balance between the initial tack and cohesive force of the pressure-sensitive adhesive. The viscosity of the prepolymer can be tested under the following conditions: temperature 23±0.5℃, relative humidity 50±5%, and rotational speed / shear rate 20 rpm.

[0031] Crosslinking agents are reagents used to react with prepolymers to increase the degree of crosslinking in the system. One molecule of a crosslinking agent has at least two alkenyl groups. For every 100 parts of prepolymer, the crosslinking agent can be 0.08 parts, 0.09 parts, 0.1 parts, 0.11 parts, 0.12 parts, etc. The extremely low amount of crosslinking agent enables micro-crosslinking of the system, improving cohesion without sacrificing viscosity.

[0032] The primary photoinitiator is used to initiate further polymerization of the prepolymer and the polymerization reaction between the crosslinking agent and the prepolymer. Relative to 100 parts of the prepolymer, the primary photoinitiator can be 0.05 parts, 0.06 parts, 0.07 parts, 0.08 parts, 0.09 parts, 0.1 parts, 0.11 parts, 0.12 parts, etc. Using a small amount of primary photoinitiator helps reduce residual photoinitiator and avoids irritation to the human body.

[0033] Fumed silica acts as a physical crosslinking point and thixotropic agent in the system, which is beneficial for enhancing modulus and holding power. The amount of fumed silica can be 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2.0 parts, etc., relative to 100 parts of prepolymer.

[0034] In some examples, the mass ratio of acrylic acid, 2-ethylhexyl acrylate and isooctyl acrylate in the prepolymer is (9.5~9.7):(55.7~56.5):(34.0~34.6). When the amount of each monomer is within the above range, the initial tack and the bonding strength to ABS and nails can be further improved.

[0035] In some examples, the second photoinitiator accounts for 0.04% of the total mass of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate, thereby providing better control over the prepolymerization reaction.

[0036] In some examples, the amount of crosslinking agent used is 0.08 to 0.1 parts relative to 100 parts of prepolymer, which further improves the adhesion performance to ABS and nails.

[0037] In some examples, the fumed silica is hydrophobic fumed silica with an average particle size of 10nm~30nm and a specific surface area of ​​80 m² / g~150 m² / g, which can better improve the coating and wetting performance of the pressure-sensitive adhesive.

[0038] In some examples, the crosslinking agent is selected from at least one of 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, 1,3-butanediol diacrylate, and diethylene glycol diacrylate.

[0039] In some examples, the first photoinitiator and the second photoinitiator are each independently selected from at least one of 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. The first photoinitiator and the second photoinitiator may be the same or different, preferably the first photoinitiator and the second photoinitiator are of the same type, and the amount of the second photoinitiator accounts for 30% to 50% of the total amount of the first photoinitiator and the second photoinitiator.

[0040] In some examples, such as Figure 1As shown, the preparation method of UV-curable pressure-sensitive adhesive includes the following steps: S1. Prepolymer preparation: In a light-protected reaction environment and under inert gas protection (such as nitrogen or argon), accurately weigh acrylic acid (AA), 2-ethylhexyl acrylate (2-EHA), and isooctyl acrylate (IOA) monomers according to the specified ratio. First, add a portion of the photoinitiator and stir at 300-500 rpm for 25-30 minutes to ensure that the initiator is completely dissolved and the mixture is homogeneous.

[0041] Subsequently, under continuous stirring, the reaction system was irradiated with a low intensity of 3-6 mW / cm² (e.g., 5.0 mW / cm²) using an ultraviolet light source (main wavelength 365 nm). The irradiation time was controlled at 1-2 minutes. Irradiation was stopped when the viscosity of the monomer mixture reached 1000 ± 200 mPa·s, corresponding to its conversion rate, through online monitoring or sampling. This prepolymer step effectively reduces the final curing shrinkage stress and optimizes the balance between the initial tack and cohesive force of the pressure-sensitive adhesive.

[0042] S2. Final mixing and nano-dispersion: To the prepolymer obtained in step S1, the remaining photoinitiator BDK, crosslinking agent 1,6-hexanediol diacrylate (HDDA), and fumed silica are added sequentially. After initial mixing at low speed (300-500 rpm) for 5-10 minutes, the stirring speed is significantly increased to 1500-2000 rpm for high-speed shear dispersion. This high-speed dispersion process continues for 30-45 minutes until the fumed silica is completely and uniformly dispersed in the system, forming a homogeneous, fine, high-viscosity paste free of visible particles or agglomerates. This step is crucial to ensuring that the nanofiller exerts its reinforcing and thixotropic effects.

[0043] S3. Vacuum degassing: The slurry obtained in step S2 is transferred to a vacuum degassing device (such as a vacuum planetary mixer or a vacuum dryer) and degassed for 15-30 minutes at a vacuum of -0.095 MPa to -0.1 MPa to completely eliminate the air bubbles introduced during the high-speed dispersion process. Finally, a UV-curable pressure-sensitive adhesive with stable viscosity, uniformity and no air bubbles is obtained, which can be used for subsequent coating.

[0044] In some examples, steps one and two are performed separately in transparent reactors, or steps one and two can be performed in the same transparent reactor, such as a glass reactor. This facilitates observation of the degree of material dispersion.

[0045] In some examples, the tape made of the aforementioned UV-curable pressure-sensitive adhesive includes a release film and an adhesive layer disposed on the release film, the adhesive layer being made of the aforementioned UV-curable pressure-sensitive adhesive. The release film provides support for the adhesive layer. The release film may be, for example, a PET film.

[0046] In some examples, such as Figure 1 As shown, the preparation method of the tape includes: applying pressure-sensitive adhesive to a release film by scraping or die coating to form a wet adhesive layer with a thickness of 300-500 micrometers, followed by curing under ultraviolet light (main wavelength 365nm) with an energy of 800 mJ / cm²-1200 mJ / cm² to form the adhesive layer. The preparation method is simple and can be continuously produced.

[0047] The present invention will be further illustrated below through specific embodiments and comparative examples, but the scope of the present invention is not limited thereto. Example

[0048] The preparation steps of the UV-curable pressure-sensitive adhesive in this embodiment are as follows: S1. Prepolymer preparation: In a light-protected and inert gas-protected reaction environment, accurately weigh 9.7g of acrylic acid (AA), 55.7g of 2-ethylhexyl acrylate (2-EHA), 34.6g of isooctyl acrylate (IOA), and 0.04g of 2,2-dimethoxy-2-phenylacetophenone (BDK) according to the specified ratio, and add them to a 250ml glass reactor. Stir at 400rpm for 30 minutes until homogeneous and transparent, ensuring that the initiator is completely dissolved and thoroughly mixed.

[0049] Subsequently, under continuous stirring, the reaction system was irradiated with a low intensity of 5.0 mW / cm² using an ultraviolet light source (main wavelength 365nm) for 2 minutes. The irradiation time was controlled at 2 minutes. By sampling and measuring, the viscosity of the monomer mixture was increased to approximately 1010 mPa·s, corresponding to its conversion rate, and then the irradiation was stopped to obtain the prepolymer.

[0050] S2. Final mixing and nano-dispersion: To the prepolymer obtained in step S1, add the remaining photoinitiator 0.07 g of 2,2-dimethoxy-2-phenylacetophenone (BDK), the crosslinking agent 0.10 g of 1,6-hexanediol diacrylate (HDDA), and 1.7 g of hydrophobic fumed silica (AEROSIL R972, with a specific surface area of ​​approximately 110 m² / g). After initial mixing at a low speed of 400 rpm for 10 minutes, significantly increase the stirring speed to 2000 rpm for high-speed shear dispersion. This high-speed dispersion process continues for 45 minutes until the fumed silica is completely and uniformly dispersed in the system, forming a homogeneous, fine, high-viscosity paste-like slurry free of visible particles or agglomerates.

[0051] S3. Vacuum degassing: The slurry obtained in step S2 is transferred to a vacuum degassing device and degassed for 30 minutes under a vacuum of -0.1 MPa to completely eliminate the air bubbles introduced during the high-speed dispersion process. Finally, a UV-curable pressure-sensitive adhesive with stable viscosity, uniformity and no air bubbles is obtained, which can be used for subsequent coating.

[0052] The preparation steps of the tape in this embodiment are as follows: The adhesive solution obtained in step S3 is applied to the release film by scraping to form a wet adhesive layer with a thickness of 450 micrometers. It is then cured by irradiation under ultraviolet light with an energy of 1000 mJ / cm² (main wavelength 365nm) to produce a pressure-sensitive adhesive sheet. Example

[0053] The preparation steps of the UV-curable pressure-sensitive adhesive and tape in this embodiment are basically the same as those in Example 1. The difference is that in the S1 prepolymer preparation step, the amount of acrylic acid (AA) is 9.5g, the amount of 2-ethylhexyl acrylate (2-EHA) is 56.5g, and the amount of isooctyl acrylate (IOA) is 34g. The S1 prepolymerization step increases the viscosity of the monomer mixture to approximately 1120 mPa·s, corresponding to its conversion rate. In the S2 final mixing and nano-dispersion step, the amount of crosslinking agent 1,6-hexanediol diacrylate (HDDA) A is changed to 0.08g. The remaining raw materials and their amounts, as well as the specific steps, are the same as in Example 1. Example

[0054] The preparation steps of the UV-curable pressure-sensitive adhesive and tape in this embodiment are basically the same as those in Example 1. The difference is that in the S1 prepolymer preparation step, the amount of acrylic acid (AA) is 9.9g, the amount of 2-ethylhexyl acrylate (2-EHA) is 55.1g, and the amount of isooctyl acrylate (IOA) is 35g. The S1 prepolymerization step increases the viscosity of the monomer mixture to approximately 920 mPa·s, corresponding to its conversion rate. In the S2 final mixing and nano-dispersion step, the amount of crosslinking agent 1,6-hexanediol diacrylate (HDDA) A is changed to 0.12g. The remaining raw materials and their amounts, as well as the specific steps, are the same as in Example 1.

[0055] The preparation steps of the UV-curable pressure-sensitive adhesive and tape in this comparative example are basically the same as those in Example 1. The difference is that in the S1 prepolymer preparation step, acrylic acid (AA) is replaced with an equal amount of 2-EHA, that is, the monomer formula is: 65.4g of 2-ethylhexyl acrylate (2-EHA) and 34.6g of isooctyl acrylate (IOA). The S1 prepolymerization step increases the viscosity of the monomer mixture to approximately 1100 mPa·s, which corresponds to its conversion rate. The remaining raw materials and their amounts, as well as the specific steps, are the same as in Example 1.

[0056] The preparation steps of the UV-curable pressure-sensitive adhesive and tape in this comparative example are basically the same as those in Example 1, except that in the final mixing and nano-dispersion step S2, the amount of crosslinking agent 1,6-hexanediol diacrylate (HDDA) A is increased to 1.0 g. The rest is the same as in Example 1. The remaining raw materials and their amounts, as well as the specific steps, are the same as in Example 1.

[0057] The preparation steps of the UV-curable pressure-sensitive adhesive and tape in this comparative example are basically the same as those in Example 1. The formulation of this comparative example is exactly the same as that in Example 1, except that in the step of preparing the S1 prepolymer, the viscosity of the prepolymer is made to reach 4590 mPa·s. The remaining steps are the same as those in Example 1.

[0058] 1. Adhesion performance to ABS board: Apply the tape to a standard ABS test board, press it once with a 2kg roller at a speed of 300mm / min, and leave it at room temperature for 24 hours. Then test the 180° peel strength (N / 25mm) according to GB / T 2792 standard.

[0059] 2. Adhesion performance to human fingernails (simulation test): Initial adhesion: Gently apply a 10mm*10mm sample of tape to a clean and dry human fingernail, press it once with your finger, and immediately peel it off slowly in a 180° direction. Evaluate the peeling feel (divided into: very easy to peel, slightly resistant, very resistant, and cannot be easily peeled off).

[0060] Adhesion holding: A 10mm*10mm piece of tape was attached to a fingernail, a 200g weight was attached, and the time (min) it took for the tape to slip off in a 40℃ constant temperature chamber was recorded.

[0061] 3. Initial tack: slant-plane rolling ball.

[0062] 4. The uniformity of coating and the transparency of the cured adhesive layer were observed during the preparation process.

[0063] Table 1 Test Results Test Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 ABS peel strength (N / 25mm) 35.2 33.5 31.8 26.5 18.4 26.8 Initial adhesiveness of nails It cannot be easily peeled off, resembling "welding". The adhesive is strong and has a good peel-off feel. The adhesive is firm, but can be slightly peeled off. Slight adhesion, detaches upon contact It adheres firmly, but feels like the adhesive is breaking when peeling it off. The adhesive is relatively strong, but it wets slowly, resulting in some areas not adhering properly. Adhesion to nails (min) >60 (did not fall off after 1 hour) >60 (did not fall off after 1 hour) >60 (did not fall off after 1 hour) 4min >60 (did not fall off after 1 hour) 22min Initial tack (slant plane rolling ball method, #) ＞32# 31# 30# ＞32# 8# 22# Coating uniformity Excellent good good good good Poor quality with leveling defects Transparency of the cured adhesive layer High transparency High transparency High transparency High transparency High transparency Slightly turbid Results analysis: Example 1 of the present invention yields a high-performance UV-curable pressure-sensitive adhesive, which solves the technical problem of ultra-high adhesion of traditional pressure-sensitive adhesives to both ABS plastic and human fingernails, and has broad prospects for industrial application.

[0064] The raw material dosage and prepolymer viscosity of Examples 2 and 3 are slightly different from those of Example 1. The pressure-sensitive adhesives of Examples 2 and 3 also exhibit excellent ABS and nail bonding performance, especially the holding time of more than 60 minutes and the initial tack is maintained at a high level (≥30#), which proves that the formulation of the present invention has reliable technical effects within the scope of the present invention.

[0065] Comparative Example 1, which did not use acrylic (AA), resulted in a pressure-sensitive adhesive that completely lost its adhesion to ABS and nails.

[0066] In Comparative Example 2, although the cohesive force was enhanced after increasing the amount of HDDA, the tack (especially the rapid wetting and adhesion to nails) and initial tack decreased significantly, proving that the extremely low amount of about 0.1 parts is the key to achieving the best balance of tack and cohesive force in this invention.

[0067] Comparative Example 3 showed excessive prepolymerization, resulting in decreased adhesive performance. The peel strength against ABS dropped to 26.8 N / 25 mm, and the tack to a fingernail was only 22 minutes. Initial tack was significantly reduced: only 22# in the rolling ball test, indicating poor colloid wettability. Processing performance deteriorated: the adhesive layer was cloudy and unevenly coated, indicating that excessive prepolymerization led to a wider molecular weight distribution and poorer system rheology. This highlights the importance of prepolymer viscosity control: excessive prepolymerization causes the system to form a network structure prematurely, affecting subsequent nano-dispersion and interfacial wetting, leading to a decline in overall performance.

[0068] Finally, it should be emphasized that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A UV-curable pressure-sensitive adhesive, characterized in that... It contains the following components by weight: 100 parts of prepolymer Crosslinking agent 0.08 parts to 0.12 parts, The first photoinitiator is 0.05 to 0.12 parts. Fumed silica 1.5 to 2.0 parts; The prepolymer is polymerized from acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate under a second photoinitiator, wherein the mass ratio of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate is (9.5~9.9):(55.1~56.5):(34.0~35.0), and the second photoinitiator accounts for 0.03%~0.05% of the total mass of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate; the viscosity of the prepolymer is 1000±200 mPa·s. One molecule of the crosslinking agent has at least two alkenyl groups.

2. The UV-curable pressure-sensitive adhesive according to claim 1, characterized in that: In the prepolymer, the mass ratio of acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate is (9.5~9.7):(55.7~56.5):(34.0~34.6). The second photoinitiator accounts for 0.04% of the total mass of acrylic acid, 2-ethylhexyl acrylate and isooctyl acrylate.

3. The UV-curable pressure-sensitive adhesive according to claim 1 or 2, characterized in that: The amount of crosslinking agent is 0.08 to 0.1 parts relative to 100 parts of the prepolymer.

4. The UV-curable pressure-sensitive adhesive according to claim 1 or 2, characterized in that: The fumed silica is hydrophobic fumed silica with an average particle size of 10nm~30nm and a specific surface area of ​​80 m² / g~150 m² / g.

5. A UV-curable pressure-sensitive adhesive according to claim 1 or 2, characterized in that: The crosslinking agent is selected from at least one of 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, 1,3-butanediol diacrylate, and diethylene glycol diacrylate. The first photoinitiator and the second photoinitiator are each independently selected from at least one of 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

6. A method for preparing a UV-curable pressure-sensitive adhesive according to any one of claims 1 to 5, characterized in that... Includes the following steps: Step 1: In a light-protected and inert gas-protected reaction environment, accurately weigh acrylic acid, 2-ethylhexyl acrylate, and isooctyl acrylate monomers, add the second photoinitiator, and stir and mix at 300 rpm to 500 rpm for 25 to 30 minutes to ensure that the initiator is completely dissolved and the mixture is uniform. Then, under continuous stirring, irradiate the reaction system with ultraviolet light at an irradiation intensity of 3 mW / cm² to 6 mW / cm² for 1 to 2 minutes. Measure the viscosity of the prepolymer mixture by online monitoring or sampling. When the viscosity rises to 1000 ± 200 mPa·s, stop the irradiation to obtain the prepolymer. Step 2: Add the first photoinitiator, crosslinking agent and nano-fumed silica to the prepolymer. After initial mixing for 5 to 10 minutes at 300 rpm to 500 rpm, increase the stirring speed to 1500 rpm to 2000 rpm for high-speed shear dispersion. The high-speed dispersion process lasts for 30 to 45 minutes to form a uniform, fine paste slurry without visible particles or agglomerates. Step 3: Transfer the obtained paste to a vacuum degassing device and degas for 15 to 30 minutes under a vacuum of -0.095 MPa to -0.1 MPa to obtain pressure-sensitive adhesive.

7. The preparation method according to claim 6, characterized in that: Step one and step two are respectively carried out in a transparent reaction vessel; The dominant wavelength of the ultraviolet light in step one is 365nm; The inert gas is nitrogen or argon; The vacuum degassing device is a vacuum planetary mixer or a vacuum dryer.

8. An adhesive tape, comprising a release film and an adhesive layer disposed on the release film, characterized in that: The adhesive layer is made of a UV-curable pressure-sensitive adhesive as described in any one of claims 1 to 5, or a pressure-sensitive adhesive obtained by the preparation method described in claim 6 or 7.

9. The method for preparing an adhesive tape according to claim 8, characterized in that... Includes the following steps: The pressure-sensitive adhesive is applied to the release film by scraping or die coating to form a wet adhesive layer with a thickness of 300 micrometers to 500 micrometers. It is then cured by irradiation under ultraviolet light with an energy of 800 mJ / cm² to 1200 mJ / cm² to form an adhesive layer.

10. An adhesive composite structure, characterized in that... The adhesive comprises an object to be bonded and an adhesive layer bonded to the surface of the object; the object to be bonded is a low surface energy plastic or a biological fingernail, wherein the low surface energy plastic is ABS, PE, PP or PS; the adhesive layer is a UV-curable pressure-sensitive adhesive as described in any one of claims 1 to 5, or a pressure-sensitive adhesive obtained by the preparation method described in claim 6 or 7, or an adhesive tape as described in claim 8, or an adhesive tape obtained by the preparation method described in claim 9.

Images