A UV-moisture dual-cured high-temperature-resistant hot melt acrylic adhesive tape and a preparation process thereof

Abstract

The application discloses a UV and moisture dual-cured high-temperature-resistant hot-melt acrylate pressure-sensitive adhesive tape and a preparation process thereof, and belongs to the technical field of high polymer materials. The pressure-sensitive adhesive tape comprises a base material and an adhesive layer. Raw materials of the adhesive layer comprise acrylate prepolymer containing a side chain containing a vinyl ether group, modified terpene resin containing a phenolic hydroxyl group, alicyclic epoxy functional silane, a cationic photoinitiator and an antioxidant. By controlling the molar ratio of the phenolic hydroxyl group and the vinyl ether, the tackifying resin is chemically grafted into the polymer network by using the cationic chain transfer reaction, and the double mechanism of the light-induced cationic polymerization and the acid-catalyzed moisture curing is combined, so that the problems of poor temperature resistance and oxygen inhibition of the traditional hot-melt adhesive are solved. The tape has excellent high-temperature shear resistance, high initial adhesion and deep curing characteristics, and the preparation process has good hot-melt processing stability.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a UV-cured, moisture-resistant, high-temperature hot-melt acrylic tape and its preparation process. Background Technology

[0002] Acrylic hot melt pressure-sensitive adhesives, due to their absence of volatile organic solvents, meet current stringent environmental regulations and offer manufacturing advantages such as high production efficiency, fast coating speed, and low energy consumption. They have become a significant development direction in the adhesive industry, replacing traditional solvent-based adhesives. Compared to rubber-based hot melt adhesives, acrylic systems exhibit superior oxidation resistance, weather resistance, and optical transparency, making them widely used in fields with high requirements for appearance and aging resistance, such as electronic and electrical assembly, automotive interior bonding, medical dressings, and building decoration materials.

[0003] In existing industrial technology systems, to ensure that acrylic hot melt adhesives acquire sufficient cohesive strength to resist shear failure after coating, ultraviolet (UV) curing technology is typically used to initiate cross-linking between polymer molecular chains. Simultaneously, to balance the initial tack, peel strength, and wetting properties of pressure-sensitive adhesives, a certain proportion of tackifying resins is usually added to the formulation. These tackifying resins are mostly low-molecular-weight rosin derivatives, terpene resins, or petroleum resins. They are dispersed in the acrylic polymer matrix through physical blending, utilizing their low molecular weight and high glass transition temperature to adjust the rheological properties of the adhesive, enabling it to quickly wet the surface of the adherends and establish adhesion.

[0004] However, this type of acrylate hot melt pressure-sensitive adhesive based on physical blending modification has significant performance limitations in high-temperature applications. Due to the lack of chemical bond anchoring between the tackifying resin and the polymer matrix, these free small molecule compounds are prone to molecular chain segment slippage and migration under high-temperature conditions, resulting in a strong plasticizing effect on the crosslinking network. This leads to rapid softening of the adhesive layer, a decrease in modulus, and loss of cohesion after heating. Consequently, the tape is prone to overflow, slippage, and even detachment from the substrate surface when subjected to continuous shear force or high-temperature load, making it difficult to meet the stringent requirements for high-temperature shear resistance of pressure-sensitive tapes in high-end manufacturing processes. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a UV-cured, moisture-cured, high-temperature resistant hot-melt acrylic tape and its preparation process. This solves the problems of insufficient shear strength and heat resistance of existing acrylic hot-melt pressure-sensitive adhesives under high-temperature environments due to the physical plasticizing effect and migration of tackifying resins, as well as the oxygen inhibition and incomplete deep curing issues of traditional free radical curing systems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Firstly, the present invention provides a UV-curable, moisture-resistant, high-temperature hot-melt acrylic pressure-sensitive tape, employing the following technical solution: A UV- and moisture-curing, high-temperature resistant hot-melt acrylic pressure-sensitive tape includes a substrate and an adhesive layer formed on at least one side of the substrate. The adhesive layer is made from raw materials comprising the following parts by weight: 100 parts of an acrylic prepolymer with vinyl ether groups in the side chain; 20-45 parts of a modified terpene resin containing phenolic hydroxyl groups; 5-15 parts of an alicyclic epoxy-functionalized silane; 1-3 parts of a cationic photoinitiator; and optionally 0.1-0.5 parts of an antioxidant.

[0007] By adopting the above technical solution, this invention utilizes a dual mechanism of cationic curing and moisture curing, combined with the chemical interactions between specific functional groups, to achieve a synergistic improvement in the high-temperature resistance and initial tack of pressure-sensitive adhesive tape. The specific mechanism and effects are described below: Chemical Modification of Tackifying Resins Based on Cationic Chain Transfer: Unlike existing technologies where tackifying resins are merely physical fillers, this invention utilizes modified terpene resins containing phenolic hydroxyl groups in the reaction. In a cationic photoinitiation system, the protic acid generated by the photoinitiator initiates the cationic copolymerization of vinyl ether groups in the matrix resin and epoxy groups in the epoxy-functionalized silane. During this process, the phenolic hydroxyl groups in the modified terpene resin act as chain transfer agents in the polymerization reaction, causing chain transfer from the growing polymer carbocation chain ends to the phenolic hydroxyl groups. This grafts the originally free small-molecule tackifying resin into the polymer backbone network through chemical bonds. This chemical bonding fixes the tackifying resin, preventing it from migrating or softening at high temperatures, thereby significantly improving the heat shear failure temperature (SAFT) of the adhesive layer while retaining the resin's tackifying function.

[0008] Synergistic effect of dual curing: The system uses UV curing to provide initial strength and utilizes alicyclic epoxy-functionalized silanes for cross-linking; simultaneously, the photoacids generated during the UV stage continue to act as catalysts, catalyzing the hydrolysis and condensation reaction of alkoxy groups in the silanes with ambient moisture in subsequent processes, forming a Si-O-Si inorganic cross-linked network. This dual network structure eliminates the influence of oxygen inhibition and solves the problem of insufficient UV penetration depth, improving the temperature resistance and weather resistance of the final cured product.

[0009] Preferably, in the raw material, the ratio R of the molar amount of hydroxyl groups provided by the modified terpene resin containing phenolic hydroxyl groups to the molar amount of vinyl ether groups provided by the acrylate prepolymer with vinyl ether groups in the side chain satisfies: 0.30 ≤ R ≤ 0.60.

[0010] By employing the above technical solution, controlling the molar ratio R of hydroxyl groups to vinyl ethers is crucial for balancing the degree of chain transfer and the density of the crosslinked network. When the R value is controlled between 0.30 and 0.60, it ensures that the tackifying resin has sufficient grafting rate to improve heat resistance, while avoiding a decrease in cohesive strength caused by excessive chain transfer leading to an excessively low polymer molecular weight.

[0011] Preferably, the softening point of the modified terpene resin containing phenolic hydroxyl groups is 115℃-125℃, the hydroxyl value is 50-80mgKOH / g, and the number average molecular weight is 600-1000g / mol; the alicyclic epoxy functionalized silane is β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0012] By adopting the above technical solution, the selection of resins with a specific hydroxyl value range ensures that the concentration of active sites is appropriate; the molecular structure of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane contains both highly reactive alicyclic epoxy groups and methoxysilyl groups, which can effectively connect organic networks and inorganic networks.

[0013] Preferably, the cationic photoinitiator is a triarylthionium hexafluoroantimonate or a triarylthionium hexafluorophosphate, and the thermal decomposition temperature of the cationic photoinitiator is greater than 160°C.

[0014] By adopting the above technical solution, the technical problem of thermally initiated gelation of cationic hot melt adhesives during high-temperature processing is suppressed by selecting initiators with high thermal decomposition temperature, thus ensuring the rheological stability of the adhesive during the melt coating stage.

[0015] Preferably, the acrylate prepolymer with vinyl ether groups in the side chain is obtained by solution polymerization and grafting reaction of monomers comprising the following weight percentages: 50%-60% 2-ethylhexyl acrylate; 25%-35% n-butyl acrylate; 10%-20% 4-hydroxybutyl acrylate; and 2-(vinyloxy)ethyl isocyanate, wherein the molar amount of 2-(vinyloxy)ethyl isocyanate is 85%-95% of the molar amount of 4-hydroxybutyl acrylate.

[0016] By adopting the above technical solution, the monomer composition and grafting ratio construct a matrix framework with a suitable glass transition temperature (Tg) and reactive site density. Retaining trace amounts of hydroxyl groups helps to improve wettability to the substrate, while the high grafting rate ensures the crosslinking density of subsequent cationic curing.

[0017] Secondly, the present invention provides a preparation process for a UV-cured, moisture-resistant, high-temperature hot-melt acrylic pressure-sensitive tape, employing the following technical solution: A process for preparing a UV-cured, moisture-resistant, high-temperature hot-melt acrylic pressure-sensitive tape includes the following steps: S1. Resin melting and mixing: The acrylate prepolymer with vinyl ether groups in the side chain is heated and melted, and the modified terpene resin containing phenolic hydroxyl groups and antioxidant are added under vacuum conditions and mixed evenly to obtain the matrix adhesive. S2. Functional component dispersion: The temperature of the matrix adhesive is reduced, and the alicyclic epoxy functionalized silane is added under vacuum conditions and stirred and dispersed; then the temperature is further reduced, and the cationic photoinitiator is added under light-protected conditions, and the mixture is dispersed evenly to obtain a hot melt pressure-sensitive adhesive composition. S3. Coating and curing: The hot melt pressure-sensitive adhesive composition is hot melt coated onto the substrate, and then cured by UV radiation and moisture curing to obtain the tape.

[0018] By adopting the above technical solution, this preparation process achieves processing stability of the cationic system in the hot-melt state through segmented temperature control and optimization of the feeding sequence.

[0019] This invention provides a UV- and moisture-cured high-temperature resistant hot-melt acrylic tape and its preparation process. It offers the following advantages: 1. This invention introduces a modified terpene resin containing phenolic hydroxyl groups into a cationic curing system and controls a specific molar ratio. By utilizing the chain transfer reaction mechanism of cationic polymerization, small molecule tackifying resin is chemically grafted into the polymer backbone network. This chemical bonding effectively restricts the molecular chain slippage and migration of the tackifying resin at high temperatures, solving the problem of poor temperature resistance caused by the softening of the tackifier in traditional hot melt pressure-sensitive adhesives. This invention achieves the technical effect of significantly improving the high-temperature shear resistance and cohesive strength of the tape while maintaining good initial tack.

[0020] 2. This invention employs a dual curing mechanism of cationic photocuring and acid-catalyzed moisture curing. The strong acid generated by photolysis first initiates the rapid polymerization of vinyl ethers and epoxy groups to establish initial strength. Subsequently, the acid continues to catalyze the hydrolysis and condensation reaction of silane functional groups with ambient moisture to form an inorganic cross-linked network. This relay reaction mode overcomes the oxygen inhibition defects and limited penetration depth of ultraviolet light in traditional free radical systems, achieving the technical effect of no adhesion on the tape surface and complete curing of the deep part of the thick adhesive layer.

[0021] 3. This invention significantly improves the thermal stability of the initiator in a high-temperature melting environment by utilizing the interaction between the phenolic hydroxyl groups in the phenol-modified terpene resin and the cationic photoinitiator. It effectively suppresses the early uncontrolled polymerization or gelation caused by the trace thermal decomposition of the initiator during the hot melt coating stage of the adhesive, solves the problem of short pot life and easy explosive polymerization of cationic systems in hot melt processing, and achieves the effect of maintaining the rheological stability of the adhesive composition at high temperature for a long time and meeting the requirements of industrial continuous coating. Attached Figure Description

[0022] Figure 1 This is a flowchart of the preparation process of the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see the appendix Figure 1 This invention provides a UV-cured, moisture-resistant, high-temperature hot-melt acrylic tape and its preparation process.

[0025] The main raw materials and reagents used in the following examples and comparative examples are sourced and specified as follows. Unless otherwise specified, the ethyl acetate solvent, azobisisobutyronitrile (AIBN) initiator, dibutyltin dilaurate (DBTDL) catalyst, and hindered phenolic antioxidant 1010 and other general-purpose additives used in the preparation process are all commercially available analytical grade or industrial premium grade products.

[0026] n-Butyl acrylate, purity ≥99.5%; 2-Ethylhexyl acrylate, purity ≥99.5%; 4-Hydroxybutyl acrylate, purity ≥97%, containing active primary hydroxyl groups; 2-(Vinyloxy)ethyl isocyanate, purity ≥98%, containing isocyanate and vinyl ether groups within the molecule.

[0027] The acrylate prepolymer with vinyl ether groups in the side chain (matrix resin A) is not a commercially available product. It is prepared by solution polymerization and graft modification of the above monomers. The specific preparation method is described in the preparation example below.

[0028] Phenolic modified terpene resins (resin B1 and resin B2) are copolymers of terpenes and phenol, with a softening point of 115℃-125℃, a hydroxyl value of 50-80 mgKOH / g, and a number-average molecular weight of 600-1000 g / mol. The molecular structure contains active phenolic hydroxyl groups. Hydrogenated petroleum resin (comparative resin B3) is a dicyclopentadiene hydrogenated resin with a softening point of 115℃ and a hydroxyl value of <1.0 mgKOH / g. Polyterpene resin (comparative resin B4) has a softening point of 115℃ and a hydroxyl value of <5.0 mgKOH / g.

[0029] β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, purity ≥98%, containing alicyclic epoxy groups and methoxysilanes in the molecule; a mixture of triarylthiohexafluoroantimony salts, 50wt% propylene carbonate solution, thermal decomposition temperature >160℃.

[0030] Preparation example: Preparation Example 1: This preparation example provides an acrylate prepolymer (matrix resin A1) with vinyl ether groups in the side chain, and its preparation process includes the following steps: (1) In a four-necked flask equipped with a mechanical stirrer, reflux condenser, thermometer and nitrogen delivery tube, add 550g of 2-ethylhexyl acrylate, 300g of n-butyl acrylate, 150g of 4-hydroxybutyl acrylate and 800g of ethyl acetate solvent; after purging with high-purity nitrogen to remove oxygen for 30 minutes, start stirring and heat to 78°C. (2) Dissolve 2.5g of azobisisobutyronitrile in 50g of ethyl acetate, add it dropwise into a flask to initiate the polymerization reaction, keep the reaction at 78°C for 8 hours until the monomer conversion rate reaches more than 99%, and obtain a hydroxyl-containing acrylate copolymer solution. (3) Lower the temperature of the above solution to 55°C, add 0.15g of dibutyltin dilaurate catalyst and 0.5g of p-hydroxyanisole (MEHQ, as a polymerization inhibitor), and then slowly add 106g of 2-(vinyloxy)ethyl isocyanate (corresponding to 90% of the molar amount of 4-hydroxybutyl acrylate), controlling the dropping rate to keep the reaction temperature below 60°C; after the addition is complete, keep the reaction at 55°C for 4 hours until the characteristic peak of the isocyanate group (-NCO, approximately 2270 cm⁻¹) is detected in the infrared spectrum. -1 ) disappear completely; (4) Transfer the reaction solution to a vacuum devolatilization vessel, slowly raise the temperature to 115°C, and gradually increase the vacuum to -0.098 MPa. Maintain vacuum devolatilization for 1.5 hours to completely remove ethyl acetate solvent and low molecular weight volatiles. Discharge the material while it is hot and cool it to obtain a semi-transparent viscous matrix resin A1.

[0031] Preparation Example 2: This preparation example provides an acrylate prepolymer (matrix resin A2) with vinyl ether groups in the side chain, which is designed as a high-functionality, low-molecular-weight version. The preparation process includes the following steps: (1) In a four-necked flask equipped with a mechanical stirrer, reflux condenser, thermometer and nitrogen delivery tube, add 500g of 2-ethylhexyl acrylate, 300g of n-butyl acrylate, 200g of 4-hydroxybutyl acrylate and 800g of ethyl acetate solvent; after purging with high-purity nitrogen to remove oxygen for 30 minutes, start stirring and heat to 80°C. (2) Dissolve 4.0g of azobisisobutyronitrile in 50g of ethyl acetate, add it dropwise into the flask to initiate the polymerization reaction, keep the reaction at 80℃ for 7 hours until the monomer conversion rate reaches more than 99%; (3) Cool down to 55°C, add 0.2g of dibutyltin dilaurate and 0.5g of MEHQ, and then add 149g of 2-(vinyloxy)ethyl isocyanate (95% of the molar amount of 4-hydroxybutyl acrylate); after the addition is complete, keep the reaction at 55°C for 4 hours until the NCO characteristic peak disappears. (4) Transfer the reaction solution to a vacuum devolatilization vessel and devolatilize it at 115°C and -0.098MPa for 1.5 hours. Discharge the material while it is hot to obtain matrix resin A2.

[0032] Preparation Example 3: This preparation example provides an acrylate prepolymer (matrix resin A3) with vinyl ether groups in the side chain, which is designed as a low-functionality, high-molecular-weight version. The preparation process includes the following steps: (1) In a four-necked flask equipped with a mechanical stirrer, reflux condenser, thermometer and nitrogen delivery tube, add 600g of 2-ethylhexyl acrylate, 300g of n-butyl acrylate, 100g of 4-hydroxybutyl acrylate and 900g of ethyl acetate solvent; after purging with high-purity nitrogen to remove oxygen for 30 minutes, start stirring and heat to 75°C. (2) Dissolve 1.8g of azobisisobutyronitrile in 50g of ethyl acetate, add it dropwise into the flask to initiate the polymerization reaction, keep the reaction at 75°C for 9 hours until the monomer conversion rate reaches more than 99%; (3) Cool down to 55°C, add 0.1g dibutyltin dilaurate and 0.5g MEHQ, then add 67g of 2-(vinyloxy)ethyl isocyanate (corresponding to 85% of the molar amount of 4-hydroxybutyl acrylate); after the addition is complete, keep the reaction at 55°C for 5 hours until the NCO characteristic peak disappears. (4) The reaction solution was transferred to a vacuum devolatilization vessel and devolatilized at 115°C and -0.098 MPa for 1.5 hours. The solution was discharged while hot to obtain matrix resin A3.

[0033] Example: Example 1: This embodiment provides a UV-moisture dual-curing high-temperature resistant hot-melt acrylic tape and its preparation process. The formula and specific steps are as follows: Ingredient Measurement: Weigh 100 parts (by weight, the same below) of the matrix resin A1 obtained in Preparation Example 1, 33 parts of phenol-modified terpene resin B1 (hydroxyl value 65 mg KOH / g), 10 parts of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2 parts of triarylthionium hexafluoroantimonyate initiator, and 0.3 parts of antioxidant 1010.

[0034] Resin melting and tackifier mixing: Add matrix resin A1 to a vacuum planetary mixer with a heating jacket and heat it to 120°C to melt it; add antioxidant 1010 and phenol-modified terpene resin B1, start stirring (40 rpm), and evacuate to -0.095 MPa. Under these conditions, degas and stir for 25 minutes until the mixture is homogeneous and transparent.

[0035] Parameter calculation: Based on the amount of feed, the ratio of the molar amount of hydroxyl groups (nOH) provided by the tackifying resin to the molar amount of vinyl ethers (nVE) provided by the matrix resin in the system is R≈0.45, which is within the preferred range and aims to balance the initial tack and heat resistance.

[0036] Crosslinking agent dispersion: Lower the temperature of the mixture to 100°C, add β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, maintain a vacuum state, and stir at 50 rpm for 15 minutes.

[0037] Initiator dispersion: Strictly control the material temperature to drop to 90℃, add the triarylsulfonium hexafluoroantimony salt initiator under light-protected conditions; increase the stirring speed to 70 rpm, disperse quickly for 8 minutes, then stop stirring and discharge the material while it is still hot.

[0038] Coating and Curing: The adhesive is heated to 105℃ and coated onto a 50μm thick PET film through a slit die, with the coating thickness controlled at 100μm. The coated adhesive layer then passes through a UV-LED irradiation zone (wavelength 365nm) along the production line, with the irradiation energy set to 450mJ / cm². 2 The adhesive layer immediately loses its fluidity; after winding, the tape is placed in a constant temperature and humidity chamber at 40℃ and 60% relative humidity for 24 hours to complete acid-catalyzed moisture curing.

[0039] Example 2: This embodiment aims to verify the lower limit of the process parameter window (R=0.30) and provides a UV-cured, moisture-resistant, high-temperature hot-melt acrylic tape and its preparation process, including the following steps: Ingredient measurement: Weigh 100 parts of matrix resin A1 obtained in Preparation Example 1, 22 parts of phenol-modified terpene resin B1 (hydroxyl value 65 mg KOH / g), 10 parts of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2 parts of triarylthionium hexafluoroantimonyate initiator, and 0.3 parts of antioxidant 1010.

[0040] Resin melting and mixing: The matrix resin A1 was melted at 115°C; antioxidant and phenol-modified terpene resin B1 were added, and the mixture was stirred at 40 rpm for 30 minutes under vacuum (-0.09 MPa).

[0041] Parameter calculation: The calculated hydroxyl / vinyl ether molar ratio of the system is R≈0.30, which is within the lower limit critical value of the effective chain transfer reaction set by this invention.

[0042] Functional component dispersion: Cool to 100℃, add silane crosslinking agent and stir for 10 minutes; continue to cool to 85℃, add photoinitiator in the dark, disperse at high speed (80 rpm) for 5 minutes and then discharge.

[0043] Coating and curing: The adhesive was melt-coated at 100℃, with a layer thickness of 50μm; the UV irradiation energy was set to 300mJ / cm². 2 After winding, allow it to mature naturally at 25℃ and 55%RH for 48 hours.

[0044] Example 3: This embodiment aims to verify the upper limit of the process parameter window (R=0.60) and provides a UV-cured, moisture-resistant, high-temperature hot-melt acrylic tape and its preparation process, including the following steps: Ingredient measurement: Weigh 100 parts of matrix resin A1 obtained in Preparation Example 1, 44 parts of phenol-modified terpene resin B1 (hydroxyl value 65 mg KOH / g), 10 parts of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2 parts of triarylthionium hexafluoroantimonyate initiator, and 0.3 parts of antioxidant 1010.

[0045] Resin melting and mixing: Melt the matrix resin A1 at 120°C; add antioxidant and phenol-modified terpene resin B1, and stir under vacuum for 20 minutes.

[0046] Parameter calculation: The calculated hydroxyl / vinyl ether molar ratio of the system is R≈0.60, which is within the upper limit critical value set by this invention to prevent excessive chain transfer from causing cohesive destruction.

[0047] Functional component dispersion: Cool to 105℃, add silane crosslinking agent and mix; cool to 95℃, add photoinitiator in the dark, disperse for 10 minutes and then discharge.

[0048] Coating and curing: The adhesive was melt-coated at 110℃, with a layer thickness of 150μm; the UV irradiation energy was set to 600mJ / cm². 2 After winding, it is cured at 45℃ and 70%RH for 24 hours.

[0049] Example 4: This embodiment uses a high-functionality matrix resin (resin A2) to prepare a high-shear strength tape, including the following steps: Ingredient measurement: Weigh 100 parts of matrix resin A2 (with high vinyl ether content) obtained in Preparation Example 2, 35 parts of phenol-modified terpene resin B1, 15 parts of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3 parts of triarylthionium hexafluoroantimony salt initiator, and 0.5 parts of antioxidant 1010.

[0050] Resin melting and mixing: Melt the matrix resin A2 at 110°C; add antioxidant and resin B1, and stir under vacuum for 30 minutes.

[0051] Parameter calculation: By adjusting the viscosity modifier ratio, R≈0.35 is controlled.

[0052] Functional component dispersion: Cool to 95℃ and add silane crosslinking agent; cool to 90℃, add photoinitiator in the dark, and disperse for 10 minutes.

[0053] Coating and curing: Coating temperature 105℃, adhesive layer thickness 80μm; UV irradiation energy 500mJ / cm² 2 The curing conditions are 40℃ / 60%RH for 36 hours.

[0054] Example 5: This embodiment uses a low-functionality matrix resin (resin A3) and different types of tackifying resins to prepare an adhesive tape with good initial tack, including the following steps: Ingredient Measurement: Weigh 100 parts of the matrix resin A3 (low vinyl ether content) obtained in Preparation Example 3, 31 parts of phenol-modified terpene resin B2 (softening point 125℃, hydroxyl value 55mgKOH / g), 5 parts of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 1.5 parts of triarylthionium hexafluoroantimonyate initiator, and 0.2 parts of antioxidant 1010.

[0055] Resin melting and mixing: Melt the matrix resin A3 at 120°C; add antioxidant and resin B2, and stir under vacuum for 25 minutes.

[0056] Parameter calculation: The calculated hydroxyl / vinyl ether molar ratio of this system is approximately 0.55.

[0057] Dispersion of functional components: Cool to 100°C and add silane crosslinking agent; cool to 90°C, add photoinitiator in the dark, and disperse for 8 minutes.

[0058] Coating and curing: Coating temperature 110℃, adhesive layer thickness 120μm; UV irradiation energy 400mJ / cm² 2 The curing conditions are 30℃ / 60%RH for 48 hours.

[0059] Comparative example: Comparative Example 1: This comparative example aims to verify the necessity of active hydroxyl groups in the "reactive tackifier". The only difference from Example 1 is that 33 parts of "phenol-modified terpene resin B1 (hydroxyl value 65 mg KOH / g)" were replaced with an equal mass of "hydrogenated petroleum resin B3 (hydroxyl value < 1.0 mg KOH / g)". This resin does not contain active phenolic hydroxyl groups and cannot participate in cationic chain transfer reactions; it exists only as a physical plasticizer. All other raw material types, amounts, and preparation processes are exactly the same as in Example 1.

[0060] Comparative Example 2: This comparative example aims to verify the consequences of a hydroxyl / vinyl ether molar ratio (R value) below the lower limit of the scope defined in this invention (R < 0.3). The only difference from Example 1 is the significant reduction in the amount of "phenol-modified terpene resin B1," from 33 parts to 10 parts. The calculated R value for this system is approximately 0.14. All other raw material types, amounts, and preparation processes are identical to those in Example 1.

[0061] Comparative Example 3: This comparative example aims to verify the consequences of a hydroxyl / vinyl ether molar ratio (R value) exceeding the upper limit of the scope defined in this invention (R > 0.6). The only difference from Example 1 is the significant increase in the amount of "phenol-modified terpene resin B1," from 33 parts to 65 parts. The calculated R value for this system is approximately 0.88. All other raw material types, amounts, and preparation processes are identical to those in Example 1.

[0062] Comparative Example 4: This comparative example aims to verify the necessity of acid-catalyzed moisture curing in the "dual curing mechanism". The only difference from Example 1 is the removal of "β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane" and its replacement with an equimolar amount of "3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate (UVR-6110)". UVR-6110 contains only alicyclic epoxy groups for photocuring and does not contain methoxysilane groups, therefore it cannot undergo subsequent moisture crosslinking. All other raw materials and process parameters are the same as in Example 1.

[0063] Comparative Example 5: This comparative example aims to verify the specific advantages of "phenolic hydroxyl groups" over ordinary trace hydroxyl groups. The only difference from Example 1 is that 33 parts of "phenol-modified terpene resin B1" were replaced with an equal mass of "polyterpene resin B4 (hydroxyl value < 5.0 mg KOH / g)". Although the resin has a similar structure, it has not undergone phenol modification and contains only trace amounts of impurity hydroxyl groups, lacking sufficient chain transfer active sites. All other raw materials and processes are the same as in Example 1.

[0064] Comparative Example 6: This comparative example aims to provide a benchmark comparison of existing traditional free radical photocuring + moisture curing technologies. A completely different formulation system is used compared to Example 1: (1) The matrix resin is replaced with 100 parts of acrylate prepolymer with acryloyloxy (C=C double bond) side chain; (2) The initiator was replaced with: 2 parts of free radical photoinitiator (1-hydroxycyclohexylphenyl ketone, Irgacure 184). (3) Catalyst addition: 0.1 parts of dibutyltin dilaurate (DBTDL) were added as a moisture curing catalyst; (4) Tackifier used: 33 parts hydrogenated petroleum resin B3. In the preparation process, due to the presence of oxygen inhibition in the free radical system, UV irradiation is required under nitrogen protection after coating. The other curing conditions are the same.

[0065] Test Example 1: Stability of Hot Melt Processing and Surface Curing Performance Test 1. Experimental Procedure Take 500g each of the uncured adhesive samples prepared in Examples 1-5 and Comparative Examples 1-6. Place the sample in a sample cup of a Brookfield digital viscometer (equipped with a No. 27 rotor) with a heating device, heat to 120°C and maintain the temperature. After temperature equilibrium is reached, measure the initial viscosity, then maintain the temperature at 120°C and record the viscosity value every hour for 4 hours. If the sample viscosity exceeds 100,000 mPa·s or stick climbing or clumping occurs during the test, it is judged as gel and the test is terminated.

[0066] The heated sample was then coated onto the surface of a PET film through a slit die, with a controlled thickness of 100 μm. It was then irradiated in air via a UV conveyor belt at an energy of 450 mJ / cm². 2 Immediately after curing, press the surface of the adhesive layer with your finger and observe its condition. If the surface is dry, without fingerprints, and without any stickiness, it is grade A; if the surface is slightly sticky and leaves fingerprints when pressed firmly, it is grade B; if the surface is sticky to the touch, has stringiness, or adhesive transfer, it is grade C.

[0067] 2. Experimental Data Table 1: Viscosity changes over time in the molten state at 120℃ and surface curing state

[0068] 3. Results Analysis Table 1 shows that Comparative Examples 1 and 5 gelled within 2 to 3 hours of heating at 120°C, while Examples 1-5 exhibited a viscosity increase of less than 40% within 4 hours under the same conditions, and no gelation occurred. Comparative Examples 1 and 5 did not contain resins containing phenolic hydroxyl groups, indicating that in the absence of a specific stabilizing component, the thionium salt photoinitiator undergoes thermal decomposition at high temperatures to produce acid, initiating the polymerization of vinyl ether groups. In Examples 1-5, the phenolic hydroxyl groups of the phenol-modified resins interacted with the initiator, inhibiting polymerization in the dark reaction stage.

[0069] The viscosity growth rate in Example 4 was slightly higher than in the other examples, while the viscosity growth rate in Comparative Example 2 reached 190.7%, close to the gel point. The lower molar amount of phenolic hydroxyl groups in Comparative Example 2 indicates that insufficient phenolic hydroxyl group concentration leads to decreased thermal stability of the system, failing to effectively inhibit the thermal decomposition of the initiator or the growth of active centers.

[0070] The surface condition of Examples 1-5 and most comparative examples after UV curing was Grade A, while the surface condition of Comparative Example 6 was Grade C. Comparative Example 6 used a free radical curing system, which exhibited oxygen inhibition, resulting in incomplete surface curing. The cationic curing system used in the examples was unaffected by oxygen. The surface condition of Comparative Example 3 was Grade B because the excessively high hydroxyl content led to an excessively large chain transfer reaction, resulting in a low polymer molecular weight and decreased cohesion.

[0071] Test Example 2: Performance Test of Pressure-Sensitive Adhesive Tape 1. Experimental steps: The adhesive tape samples prepared in Examples 1-5 and Comparative Examples 1-6 and cured under standard conditions were subjected to the following performance tests: (1) 180° peel strength test: According to ASTM D3330 standard, a 25mm wide tape was attached to the surface of the stainless steel plate and rolled back and forth 3 times with a 2kg roller. After standing for 20 minutes, a 180° peel test was performed using a tensile testing machine at a speed of 300mm / min. The peel force value (N / 25mm) was recorded.

[0072] (2) Static Shear Heat Resistance (SAFT) Test: According to ASTM D4498 standard, the tape was adhered to a stainless steel plate with an adhesion area of ​​25mm × 25mm, and a 1kg weight was hung on it. The sample was placed in an oven and heated from 40℃ to 210℃ at a rate of 0.5℃ / min (stop if it does not fail). The failure temperature at which the tape detached was recorded. If it did not detach after heating to 210℃, it was recorded as >210℃.

[0073] (3) High-temperature holding power test: According to ASTM D3654 standard, the tape was pasted onto a stainless steel plate with an area of ​​25mm×25mm, a 1kg weight was hung on it, and it was placed in a constant temperature oven at 180℃. The time the tape remained attached was recorded. If it did not fall off after more than 24 hours, it was recorded as >24h.

[0074] 2. Experimental Data Table 2: Test Results of Key Application Performance of Pressure-Sensitive Adhesive Tapes

[0075] 3. Results Analysis Based on the data in Table 2, the technical effects of the present invention are analyzed as follows: (1) The decisive influence of chain transfer grafting on heat resistance: The SAFT values ​​of Examples 1-5 all exceeded 200°C, and the tack holding time at 180°C exceeded 24 hours. In contrast, the SAFT value of Comparative Example 1 (using hydrogenated petroleum resin without active hydroxyl groups) was only 142°C. This confirms that the phenol-modified resin in the examples was chemically bonded to the polymer network through a cationic chain transfer reaction, eliminating the plasticizing and softening effect of small molecule tackifiers at high temperatures, thereby significantly improving the high-temperature resistance.

[0076] (2) The effect of molar ratio (R value) on adhesive performance: Example 1 (R≈0.45) demonstrated the optimal balance between peel strength and heat resistance. Comparative Example 2 (R value too low) showed a SAFT value dropping to 158°C, indicating insufficient chain transfer grafting and the presence of significant free tackifier. Comparative Example 3 (R value too high), while exhibiting acceptable heat resistance (185°C), showed a significant decrease in peel strength (11.5 N / 25 mm) and cohesive failure. This is because excessive chain transfer reaction resulted in an excessively low molecular weight of the polymer backbone, damaging the cohesive strength of the adhesive layer.

[0077] (3) Synergistic effect of dual curing: The SAFT value of Comparative Example 4 (UV curing only, no moisture curing) was 165°C, significantly lower than that of Example 1. This indicates that the cross-linking network established by cationic photocuring alone is still insufficient at high temperatures. The subsequent acid-catalyzed silane moisture condensation reaction introduces a highly heat-resistant Si-O-Si inorganic framework, which plays a key role in improving the final heat resistance.

[0078] (4) Comparison with traditional technologies: Comparative Example 6 (traditional free radical system) has a SAFT value of only 125℃ and extremely poor high-temperature tack. This invention successfully breaks through the temperature resistance limit of traditional acrylic hot melt adhesives through a triple mechanism of cationic / chain transfer / moisture curing.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A UV- and moisture-curing, high-temperature resistant hot-melt acrylic pressure-sensitive tape, comprising a substrate and an adhesive layer formed on at least one side of the substrate, characterized in that, The adhesive layer is made from raw materials comprising the following parts by weight: 100 parts of acrylate prepolymer with vinyl ether groups in the side chain; 20-45 parts of modified terpene resin containing phenolic hydroxyl groups; Alicyclic epoxy-functionalized silanes, 5-15 parts; 1-3 parts of cationic photoinitiator; And an optional antioxidant of 0.1-0.5 parts.

2. The UV-cured, moisture-resistant, high-temperature hot-melt acrylic pressure-sensitive tape according to claim 1, characterized in that, In the raw materials, the ratio R of the molar amount of hydroxyl groups provided by the modified terpene resin containing phenolic hydroxyl groups to the molar amount of vinyl ether groups provided by the acrylate prepolymer with vinyl ether groups in the side chain satisfies: 0.30 ≤ R ≤ 0.

60.

3. The UV-cured, moisture-resistant, high-temperature hot-melt acrylic pressure-sensitive tape according to claim 1, characterized in that, The softening point of the modified terpene resin containing phenolic hydroxyl groups is 115℃-125℃, the hydroxyl value is 50-80mgKOH / g, and the number average molecular weight is 600-1000g / mol. The alicyclic epoxy-functionalized silane is β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

4. The UV-cured, moisture-resistant, high-temperature hot-melt acrylic pressure-sensitive tape according to claim 1, characterized in that, The cationic photoinitiator is a triarylthionium hexafluoroantimonate or a triarylthionium hexafluorophosphate, and the thermal decomposition temperature of the cationic photoinitiator is greater than 160°C.

5. The UV-cured, moisture-resistant, high-temperature hot-melt acrylic pressure-sensitive tape according to claim 1, characterized in that, The acrylate prepolymer with vinyl ether groups in the side chain is prepared by solution polymerization and grafting reaction of monomers comprising the following weight percentages: 50%-60% 2-Ethylhexyl acrylate; 25%-35% n-butyl acrylate; 4-Hydroxybutyl acrylate 10%-20%; And 2-(vinyloxy)ethyl isocyanate, wherein the molar amount of 2-(vinyloxy)ethyl isocyanate is 85%-95% of the molar amount of 4-hydroxybutyl acrylate.

6. A preparation process for a UV-cured, moisture-resistant, high-temperature hot-melt acrylic pressure-sensitive tape as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Resin melting and mixing: The acrylate prepolymer with vinyl ether groups in the side chain is heated and melted, and the modified terpene resin containing phenolic hydroxyl groups and antioxidant are added under vacuum conditions and mixed evenly to obtain the matrix adhesive. S2. Functional component dispersion: The temperature of the matrix adhesive is reduced, and the alicyclic epoxy functionalized silane is added under vacuum conditions and stirred and dispersed; then the temperature is further reduced, and the cationic photoinitiator is added under light-protected conditions, and the mixture is dispersed evenly to obtain a hot melt pressure-sensitive adhesive composition. S3. Coating and curing: The hot melt pressure-sensitive adhesive composition is hot melt coated onto the substrate, and then cured by UV radiation and moisture curing to obtain the tape.

7. The preparation process according to claim 6, characterized in that, In step S1, the method for preparing the acrylate prepolymer with vinyl ether groups in the side chain includes: (1) 2-Ethylhexyl acrylate, n-butyl acrylate and 4-hydroxybutyl acrylate are subjected to free radical solution polymerization in a solvent to obtain a hydroxyl-containing acrylate copolymer solution; (2) Add catalyst and polymerization inhibitor, add 2-(vinyloxy)ethyl isocyanate dropwise, and carry out grafting reaction at 50-60℃ until the characteristic peak of isocyanate group disappears; (3) Heat up and vacuum to remove solvent and volatiles to obtain the prepolymer.

8. The preparation process according to claim 6, characterized in that, In step S1, the heating and melting temperature is 110-120℃, and the vacuum degree is controlled between -0.09MPa and -0.098MPa; In step S2, the material temperature is controlled at 85-95°C when the cationic photoinitiator is added.

9. The preparation process according to claim 6, characterized in that, In step S3, the UV radiation curing uses a UV-LED light source or a high-pressure mercury lamp, with an irradiation energy of 300-600 mJ / cm². 2 The conditions for moisture curing are: temperature 25-45℃, relative humidity 50%-70%, and time 24-48 hours.

10. The preparation process according to claim 7, characterized in that, In step (3), the temperature of vacuum devolatilization is 110-120℃, and the polymerization inhibitor mentioned in step (2) is p-hydroxyanisole.

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