High-toughness ultraviolet curing temporary protection adhesive as well as preparation method and use method thereof

Abstract

The invention discloses a high-toughness ultraviolet curing temporary protection adhesive as well as a preparation method and a use method thereof. The high-toughness ultraviolet curing temporary protection adhesive is prepared from the following raw materials in parts by weight: 60-75 parts of polyurethane acrylate, 20-40 parts of a reactive diluent, 1-5 parts of a photoinitiator, 0.1-1 part of a flatting agent, 0.1-1 part of a defoaming agent, 0.5-5 parts of filler, 0.5-5 parts of a nano toughening agent and 0.1-5 parts of a silane coupling agent. According to the high-toughness ultraviolet curing temporary protection adhesive provided by the invention, polyfunctional polyurethane acrylate with excellent flexibility and strength is synthesized as matrix resin, and a specific type of nano flexibilizer is compounded, so that a finally cured adhesive layer has high toughness and impact resistance, and meanwhile, the high-toughness ultraviolet curing temporary protection adhesive can be applied to the field of adhesive materials. And good surface drying performance, excellent adhesion and peelability are realized.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a high-toughness UV-curable temporary protective adhesive and its preparation and application methods. Background Technology

[0002] During the production, transportation, and assembly of precision components such as electronic products (e.g., mobile phones, tablets), high-end decorative parts, and optical lenses, their surfaces (e.g., glass, polished metal, coatings) are highly susceptible to scratches, contamination, or chemical corrosion. Therefore, it is typically necessary to apply a temporary protective film or coating at the initial stage of the manufacturing process. Ultraviolet (UV) curing adhesives are widely used for these temporary protective materials due to their advantages such as fast curing speed, high efficiency, and environmental friendliness.

[0003] However, existing UV-curable temporary protective adhesives generally have the following problems: 1) Insufficient toughness: In pursuit of peelability, the adhesive layer is often designed to be brittle or have low cohesive strength, which makes it easy for the adhesive layer to crack or detach from the substrate when subjected to bending, impact or local stress, thus losing its protective function. 2) Difficulty in balancing resistance: High toughness often means high adhesion, which can lead to difficulty in peeling or the formation of adhesive residue after the protection period ends; while pursuing easy peeling may sacrifice tight adhesion to the substrate and impact protection. 3) Limited applicability: For curved, irregularly shaped, or parts that require further processing, the existing protective adhesives are not flexible and durable enough.

[0004] Therefore, developing a UV-cured temporary protective adhesive that combines high toughness, excellent surface drying effect, good adhesion, and post-treatment cleanability and peelability has significant industrial application value. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention aims to provide a high-toughness UV-curable temporary protective adhesive, its preparation method, and its application method. The adhesive achieves an ideal balance of toughness, protection, and peelability.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a high-toughness UV-curable temporary protective adhesive, comprising the following raw materials in parts by weight: 60-75 parts of polyurethane acrylate, 20-40 parts of reactive diluent 1-5 parts of photoinitiator Leveling agent 0.1-1 part, Defoamer 0.1-1 part, 0.5-5 parts of nano-toughening agent, 0.1-5 parts of silane coupling agent.

[0007] The polyurethane acrylate is a polyurethane acrylate with a functionality of 2-4 and a molecular weight of 10,000-50,000. This component serves as the main resin, providing the basic strength, flexibility, and impact resistance of the cured film.

[0008] Furthermore, the polyurethane acrylate is a product of the reaction between isocyanate-terminated polyurethane prepolymer and acrylate monomer; Furthermore, the isocyanate-terminated polyurethane prepolymer is prepared by reacting isocyanate and diol at a molar ratio of isocyanate group to hydroxyl group of (1.0-1.5):1. Further, the isocyanate is one or a mixture of more of the following: hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, phenyldimethyl diisocyanate, toluene diisocyanate, and diphenylmethyl diisocyanate; Furthermore, the isocyanate is preferably isophorone diisocyanate; Furthermore, the diol is one or more of polyether diol, polyester diol, and polycarbonate diol; Further, the polyether diol includes, but is not limited to, one or more of polyethylene oxide glycol with an average molecular weight of 2000-4000, polypropylene glycol with an average molecular weight of 2000-6000, or polytetrahydrofuran with an average molecular weight of 2000-4000. Furthermore, the polypropylene glycol is preferably polypropylene glycol with an average molecular weight of 3000-4000; Further, the polyester diol includes aromatic polyester polyols and aliphatic polyester polyols with an average molecular weight of 1000-5000, including but not limited to one or more of Desmophen1100, Desmophen 1652, Desmophen 1800, Desmophen 2000, Dynacoll 7000, Dynacoll 8000, Dynacoll 7300, Dynacoll 7200, WL-220A, HD-220, HDP-3050, and HY-3020. Furthermore, the polyester diol is preferably Desmophen 1800; Furthermore, the polycarbonate diol includes, but is not limited to, polycarbonate diols (PCDL) with an average molecular weight of 2000-4000. Furthermore, the polycarbonate diol is preferably a polycarbonate diol with an average molecular weight of 3000.

[0009] Furthermore, the acrylate monomer is a compound of hydroxyl-containing acrylate monomer and hydroxyl-free acrylate monomer; Furthermore, the molar ratio of isocyanate groups to hydroxyl groups in the isocyanate-terminated polyurethane prepolymer to the acrylate monomer is (0.8~1.5):1; Furthermore, the mass ratio of the hydroxyl-containing acrylate monomer to the hydroxyl-free acrylate monomer is 1:(0.5-3). Furthermore, the hydroxyl-containing acrylate monomer is pentaerythritol triacrylate; Furthermore, the hydroxy-free acrylate monomer is one or more of trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and ethoxylated trimethylolpropane triacrylate; Furthermore, the hydroxy-free acrylate monomer is preferably trimethylolpropane triacrylate.

[0010] Furthermore, the photoinitiator is a free radical photoinitiator, including but not limited to 2-hydroxy-2-methyl-1-phenyl-1-propanone, ethyl 2,4,6-trimethylbenzoylphosphonate, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2-benzyl-dimethylamino-1-(4-morpholinylphenyl)-but-1-one, biphenylyl dimethyl ketal dimethoxyphenyl acetophenone, α-hydroxybenzylphenyl ketone, oligo-2-hydroxy-2-methyl-1-(4-)-propanone, and ethyl 2-(4-)-propanone. (1-Methylvinyl)phenyl)acetone, benzophenone, methyl o-benzoate, methyl benzylformate, 2,2-diethoxyacetophenone, 2,2-disec-butoxyacetophenone, p-phenylbenzophenone, 2-isopropylthioxanthionone, 2-methylanthrone, 2-ethylanthrone, 2-chloroanthrone, 1,2-benzoanthrone, benzoyl ether, benzoin ether, benzoin methyl ether, benzoin isopropyl ether, α-phenylbenzoin, thioxanthionone, diethylthioxanthionone, 1,5-acetonenaphthalene, 1-hydroxycyclohexylphenyl ketone, and ethyl p-dimethylaminobenzoate are among one or more of these. Furthermore, the photoinitiator is preferably phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0011] Further, the active diluent includes, but is not limited to, butylene(meth)acrylate, cyclohexyl(meth)acrylate, dicyclopentyl(meth)acrylate, dicyclopentenyl(meth)acrylate, dicyclopentenoxyethyl(meth)acrylate, N,N-diethylaminoethyl(meth)acrylate, 2-ethoxyethyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, caprolactone-modified 2-hydroxyethyl(meth)acrylate, isobornyl(meth)acrylate, lauryl(meth)acrylate, acryloylmorpholine, and N-vinylcaprolactone. The following are one or more of the following: amide, nonylphenoxy polyethylene glycol (meth)acrylate, nonylphenoxy polypropylene glycol (meth)acrylate, phenoxyethyl methacrylate, phenoxyhydroxypropyl methacrylate, phenoxydiethylene glycol methacrylate, polyethylene glycol methacrylate, polypropylene glycol methacrylate, tetrahydrofurfuryl methacrylate, 1,6-hexanediol diacrylate, cyclotrimethylolpropane methyl acetal acrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and ethoxylated trimethylolpropane triacrylate; Further, the reactive diluent is preferably one or more selected from 1,6-hexanediol diacrylate, cyclotrimethylolpropane methyl acetal acrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate; Furthermore, the nano-toughening agent is one or more of the following: nano-silica and / or nano-alumina, nano-rubber particles, and core-shell acrylate microspheres, with the surface modified by organosilane or acrylate monomers; this component is the key to improving toughness, and the nanoparticles can absorb and disperse external stress, significantly improving the elongation at break and impact resistance of the cured film. Furthermore, the nano-toughening agent is preferably one or both of nano-silica or core-shell acrylate microspheres whose surface is modified with organosilane or acrylate monomers.

[0012] Furthermore, the leveling agent includes, but is not limited to, one or more of the following: BYK-333, HX-3310, Shin-Etsu KP-323, BYK-361N, Deqian 923, HX-3380, Surfynol 104, BYK-307, and TEGO Glide 100; Furthermore, the leveling agent is preferably BYK-333; Furthermore, the defoamer includes, but is not limited to, one or more of BYK-1790, TEGO Airex 902W, Dynol 604, Shin-Etsu KP-341, BYK-055, TEGO Foamex 810, BYK-088, TEGO Airex 920, and TEGO Flow 300; Furthermore, the defoamer is preferably BYK-1790.

[0013] Furthermore, the silane coupling agent includes, but is not limited to, one or a mixture of several of 3-aminopropyltriethoxysilane, bis[3-(trimethoxysilyl)propyl]amine, 3-methacryloyloxypropyltrimethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and N-n-butyl-3-aminopropyltrimethoxysilane; Furthermore, the silane coupling agent is preferably 3-aminopropyltriethoxysilane KH550.

[0014] Secondly, the present invention also provides a method for preparing a high-toughness UV-curable temporary protective adhesive, comprising the following steps: S1. Synthesis of isocyanate-terminated polyurethane prepolymer: One or more of polyether diols, polyester diols, and polycarbonate diols are heated to 100℃~120℃ and stirred under vacuum to remove water for 2~3 hours, removing trace amounts of moisture. The dehydrated diol or diol mixture is cooled to 50-80℃, and polyphosphoric acid is added and stirred for 10~30 minutes. Then, a measured amount of isocyanate and catalyst are added, and the reaction is stirred under vacuum. The NCO group content is monitored to reach the theoretical value of 0.7%-1.7%, thus obtaining the isocyanate-terminated polyurethane prepolymer. S2. Synthesis of polyurethane acrylate: Add a compound containing hydroxyl acrylate monomers and non-hydroxyl acrylate monomers to the polyurethane prepolymer with terminal isocyanate groups prepared in step 1 above, and react under the conditions of 70℃~80℃ and vacuum degree below 100Pa, so that the hydroxyl groups of the hydroxyl acrylate monomers react with the NCO groups at the end of the prepolymer to obtain the desired polyurethane acrylate. S3. Preparation of UV adhesive: Under light-protected conditions, the above-synthesized polyurethane acrylate, reactive diluent, photoinitiator, silane coupling agent, nano toughening agent, defoamer and leveling agent are added in sequence, and the mixture is stirred thoroughly until all components are evenly dispersed to obtain a high-toughness UV-curable temporary protective adhesive.

[0015] Preferably, the preparation method of the high-toughness UV-curable temporary protective adhesive may further include a filtration and dispensing step: filtering the mixture to remove any possible particulate matter and dispensing it.

[0016] Thirdly, the present invention also provides a method for using a high-toughness UV-curable temporary protective adhesive, comprising the following steps: (I) Pre-treat the surface of the target substrate to thoroughly remove contaminants such as grease, fingerprints, dust, and mold release agents; if stubborn stains are present, a special cleaning agent can be used for auxiliary cleaning. (II) Inject the prepared adhesive into the spraying equipment and spray it evenly onto the cleaned target substrate surface; (III) After spraying, allow the adhesive layer to stand and level. Once the surface of the adhesive layer is smooth, use a UV-LED light source with a wavelength of 365 nm or 395 nm for irradiation and curing. The irradiation energy should be controlled within the range of 500–2000 mJ / cm². (IV) Once the curing is complete, the substrate with the protective adhesive layer can be transferred to the subsequent transport or processing procedures.

[0017] Preferably, the target substrate is selected from metal, plastic, ceramic, or glass.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The high-toughness UV-curable temporary protective adhesive provided by this invention uses a synthetic multifunctional polyurethane acrylate with excellent flexibility and strength as the main resin, and is compounded with specific types of nano-toughening agents. This results in a final cured adhesive layer with high toughness and impact resistance, while also achieving good surface drying performance, excellent adhesion and peelability.

[0019] High toughness and impact resistance: The cured adhesive layer has both high elongation at break and excellent impact resistance. It is not easy to crack or fall off during subsequent processing such as bending and stamping, providing continuous and reliable process protection for the substrate. Controllable adhesion and clean peeling: During the protection period, the adhesive layer is firmly bonded to the substrate and has good surface drying effect. When peeling, it can be gently torn off at a specific angle to achieve clean removal without residue or transfer. Excellent adhesion and comprehensive protection: The dense and smooth adhesive layer can adhere well to a variety of substrates such as glass, metal, and plastic, providing effective protection against scratches, contamination, and chemical corrosion. Excellent surface drying effect: This adhesive is designed with a high-functionality resin system, which forms a dense cross-linked network after curing, significantly improving surface drying efficiency and performance, and has good practicality; Wide applicability: It is especially suitable for process protection of precision components such as glass covers of electronic products, high-end metal decorative parts, and optical lenses, meeting high standards of temporary protection requirements. Detailed Implementation

[0020] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0021] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0022] Unless otherwise specified, the temperature in the embodiments of the present invention is room temperature or ambient temperature; room temperature or ambient temperature refers to 25±1℃. Example

[0023] Preparation of a high-toughness UV-curable temporary protective adhesive: S1. Synthesis of isocyanate-terminated polyurethane prepolymer: 50 parts of Desmophen 1800 and 50 parts of polypropylene glycol (PPG 2000) with an average molecular weight of 2000 were mixed evenly, heated to 120°C, and dehydrated for 2 hours under a vacuum of less than 100 Pa; then cooled to 70°C, 0.01 parts of polyphosphoric acid were added and stirred for 10 minutes, then 15 parts of isophorone diisocyanate (IPDI) and 0.02 parts of bismuth neodecanoate catalyst were added, and reacted for 2 hours under a vacuum of less than 100 Pa to obtain an isocyanate-terminated polyurethane prepolymer with an NCO content of 1.1%. S2. Synthesis of polyurethane acrylate: 10 parts of pentaerythritol triacrylate (PETA) and 10 parts of trimethylolpropane triacrylate (TMPTA) are added to the polyurethane prepolymer with terminal isocyanate group prepared in step S1 above. The mixture is reacted at 70°C and vacuum degree below 100Pa for 2 hours to obtain polyurethane acrylate with a functionality of 3 and a molecular weight of 30000. S3. Preparation of UV adhesive: Under light-protected conditions, add 70 parts of the above-synthesized polyurethane acrylate, 1 part of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 22 parts of 1,6-hexanediol diacrylate, 18 parts of tripropylene glycol diacrylate, 1.2 parts of KH-550, 0.5 parts of surface-modified silica (Wacker H18), 0.5 parts of core-shell acrylate microspheres (Kane Ace M-577), 0.2 parts of BYK-333, and 0.2 parts of BYK-1790 in sequence, and stir thoroughly until all components are evenly dispersed to obtain the desired high-toughness UV-curable temporary protective adhesive; S4. Filtration and Packaging: Under light-protected conditions, filter the adhesive to remove any possible particulate matter and then repackage it. Example

[0024] Preparation of a high-toughness UV-curable temporary protective adhesive: S1. Synthesis of isocyanate-terminated polyurethane prepolymer: 20 parts of polytetrahydrofuran (PTMG 3000) with an average molecular weight of 3000 and 80 parts of polycarbonate diol (PCDL 4000) with an average molecular weight of 4000 were mixed evenly, heated to 120°C, and dehydrated for 2 hours under a vacuum of less than 100 Pa; then cooled to 70°C, 0.01 parts of polyphosphoric acid were added and stirred for 10 minutes, then 20 parts of isophorone diisocyanate (IPDI) and 0.02 parts of bismuth neodecanoate catalyst were added, and the mixture was reacted for 2 hours at 70°C and a vacuum of less than 100 Pa to obtain an isocyanate-terminated polyurethane prepolymer with an NCO content of 0.9%.

[0025] S2. Synthesis of polyurethane acrylate: 10 parts of pentaerythritol triacrylate (PETA) and 10 parts of trimethylolpropane triacrylate (TMPTA) are added to the polyurethane prepolymer with terminal isocyanate group prepared in step S1 above. The mixture is reacted at 70°C and vacuum degree below 100Pa for 2 hours to obtain polyurethane acrylate with a functionality of 3 and a molecular weight of 20000. S3. Preparation of UV adhesive: Under light-protected conditions, add 70 parts of the above-synthesized polyurethane acrylate, 1 part of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 22 parts of 1,6-hexanediol diacrylate, 18 parts of tripropylene glycol diacrylate, 1.2 parts of KH-550, 0.5 parts of surface-modified silica (Wacker H18), 0.5 parts of core-shell acrylate microspheres (Kane Ace M-577), 0.1 parts of BYK-333, and 0.1 parts of BYK-1790 in sequence, and stir thoroughly until all components are evenly dispersed to obtain the desired high-toughness UV-curable temporary protective adhesive; S4. Filtration and Packaging: Under light-protected conditions, filter the adhesive to remove any possible particulate matter and then repackage it. Example

[0026] Preparation of a high-toughness UV-curable temporary protective adhesive: S1. Synthesis of isocyanate-terminated polyurethane prepolymer: 70 parts of Desmophen 1800, 20 parts of polypropylene glycol (PPG 2000) with an average molecular weight of 2000, and 10 parts of polycarbonate glycol (PCDL 4000) with an average molecular weight of 4000 were mixed evenly and heated to 120°C. The mixture was then dehydrated for 2 hours under a vacuum of less than 100 Pa. Subsequently, the temperature was lowered to 70°C, and 0.01 parts of polyphosphoric acid were added and stirred for 10 minutes. Then, 20 parts of isophorone diisocyanate (IPDI) and 0.02 parts of bismuth neodecanoate catalyst were added. The mixture was reacted for 2 hours at 70°C under a vacuum of less than 100 Pa to obtain an isocyanate-terminated polyurethane prepolymer with an NCO content of 1.5%.

[0027] S2. Synthesis of polyurethane acrylate: 20 parts of pentaerythritol triacrylate (PETA) were added to the polyurethane prepolymer with terminal isocyanate group prepared in step S1 above, and the reaction was carried out at 70°C and vacuum degree below 100Pa for 2 hours to obtain polyurethane acrylate with a functionality of 3 and a molecular weight of 30000. S3. Preparation of UV adhesive: Under light-protected conditions, add 70 parts of the above-synthesized polyurethane acrylate, 1 part of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 22 parts of 1,6-hexanediol diacrylate, 18 parts of tripropylene glycol diacrylate, 1.2 parts of KH-550, 0.5 parts of surface-modified silica (Wacker H18), 0.5 parts of core-shell acrylate microspheres (Kane Ace M-577), 0.1 parts of BYK-333, and 0.1 parts of BYK-1790 in sequence, and stir thoroughly until all components are evenly dispersed to obtain the desired high-toughness UV-curable temporary protective adhesive; S4. Filtration and Packaging: Under light-protected conditions, filter the adhesive to remove any possible particulate matter and then repackage it.

[0028] Comparative Example 1: It differs from Example 3 only in that pentaerythritol triacrylate is replaced with hydroxyethyl acrylate in step S2 of polyurethane acrylate synthesis.

[0029] Comparative Example 2: It differs from Example 3 in that it does not contain nano-toughening agents (surface-modified silica and core-shell acrylate microspheres).

[0030] Comparative Example 3: Commercially available premium product (UV peelable protective adhesive).

[0031] The temporary protective adhesives prepared by the above embodiments and comparative examples were evaluated for their various properties by the following methods, and the test results are listed in Table 1 below.

[0032] Relevant performance tests: 1) Appearance Visually inspect the prepared adhesive for impurities, particles, bubbles, and uneven mixing. If none are found, the appearance is good.

[0033] 2) Viscosity at 25℃ According to GB / T 2794-1995 standard, select a suitable rotor model, add 20g of sample to the sample cell, and set the temperature to 25℃. After the temperature stabilizes, conduct the test, select a suitable speed, keep the torque between 10% and 90%, and after the viscosity is relatively stable, collect 4 points and take the average value as the test viscosity value.

[0034] 3) Body strength The adhesive solution to be tested was poured into a polytetrafluoroethylene (PTFE) mold and allowed to stand until it naturally leveled, forming a uniform adhesive layer. Then, it was irradiated with a UV-LED light source at a wavelength of 365 nm, with the irradiation energy controlled at 1000 mJ / cm² for approximately 10 seconds to complete UV curing. The cured adhesive film was removed from the mold, and dumbbell-shaped specimens were cut according to GB / T 1040.1-2018 standard, ensuring the specimen surface was flat, free of bubbles and defects. After conditioning the specimens in a standard laboratory environment, they were clamped on a mechanical testing machine and stretched at the specified tensile speed until the specimen broke. The changes in force and displacement at the point of fracture were recorded, and the overall strength was calculated.

[0035] 4) Elongation at break The adhesive solution to be tested was poured into a polytetrafluoroethylene (PTFE) mold and allowed to stand until it naturally leveled, forming a uniform adhesive layer. Then, it was irradiated with a UV-LED light source at a wavelength of 365 nm, with the irradiation energy controlled at 1000 mJ / cm² for approximately 10 seconds to complete UV curing. The cured adhesive film was removed from the mold, and dumbbell-shaped specimens were cut according to GB / T 1040.1-2018 standard, ensuring the specimen surface was flat, free of bubbles and defects. After conditioning the specimens in a standard laboratory environment, they were clamped on a mechanical testing machine and stretched at the specified tensile speed until the specimen broke. The change in gauge length at the point of specimen breakage was recorded, and the elongation at break was calculated.

[0036] 4) Shore hardness The adhesive solution to be tested is poured into a polytetrafluoroethylene (PTFE) mold and allowed to stand until it naturally levels, forming a uniform adhesive layer. Then, it is irradiated with a UV-LED light source with a wavelength of 365 nm, the irradiation energy controlled at 1000 mJ / cm², corresponding to approximately 10 seconds, to complete the UV curing. Following the GB / T 2411-1980 standard, the indenter is vertically pressed into the sample surface under test force. Using a Shore hardness tester, when the indenter surface is completely in contact with the sample surface, the tip of the indenter extends a certain length relative to the indenter plane (i.e., the depth to which the indenter penetrates the test object). The value displayed on the dial is read, and the average of four points is taken as the hardness value.

[0037] 5) Shear strength According to GB / T 528-2009 standard, two 25mm × 100mm polycarbonate (PC) test pieces were overlapped in a straight line, and an adhesive layer measuring 25mm × 25mm × 0.1mm was applied to the overlap area. Subsequently, the bonded area was irradiated with a 365nm UV-LED light source, with the energy controlled within the range of 1000mJ / cm², corresponding to an irradiation time of approximately 10 seconds. After curing, its shear strength was tested using a mechanical testing machine at a tensile speed of 50mm / min.

[0038] 6) Pull-out strength According to GB / T 528-2009 standard, two PC test pieces measuring 25mm × 100mm were overlapped in a straight line, and an adhesive layer measuring 25mm × 25mm × 0.1mm was applied to the overlap area. Subsequently, the bonded area was irradiated with a UV-LED light source with a wavelength of 365nm, controlling the energy within the range of 1000 mJ / cm², corresponding to an irradiation time of approximately 10 seconds. After curing, the tensile strength was tested using a mechanical testing machine at a tensile speed of 50mm / min.

[0039] 7) Surface drying effect The adhesive solution to be tested was poured into a polytetrafluoroethylene (PTFE) mold and allowed to stand until it naturally leveled, forming a uniform adhesive layer. Then, it was irradiated with a UV-LED light source with a wavelength of 365 nm, the irradiation energy controlled at 1000 mJ / cm², corresponding to approximately 10 seconds, to complete the UV curing. Following GB / T 1728 standard, a degreased cotton ball was gently placed on the cured surface, a 100 g weight was placed on the cotton ball, held for 5 seconds, and then the cotton ball was vertically removed. The surface was visually inspected for any remaining cotton fibers; no residue indicated good surface drying.

[0040] 8) Peeling effect The protective adhesive was evenly sprayed onto the surface of a 25mm × 100mm PC specimen. The coated area was then irradiated and cured using a 365nm UV-LED light source. The curing energy was controlled within the range of 1000 mJ / cm², corresponding to an irradiation time of approximately 10 seconds. After curing, the adhesive layer was peeled from the PC substrate using a tensile testing machine at a constant speed (300 mm / min) and a 90° peel angle. After peeling, the surface of the PC substrate and the peeled adhesive film were visually and instrumentally inspected to evaluate their surface condition and integrity.

[0041] 9) Cutting effect The protective adhesive was evenly sprayed onto the surface of a 300 mm × 300 mm PC substrate. The coated area was then irradiated and cured using a 365 nm UV-LED light source, with the energy controlled within the range of 1000 mJ / cm², corresponding to an irradiation time of approximately 10 seconds. After curing, a cutting machine was used to cut the adhesive layer to a specified shape and depth. Subsequently, the cut edges were inspected for any chipping, curling, or powdering, and it was observed whether the adhesive film detached due to the pull of the cutting tool during the cutting process.

[0042] The test data are shown in Table 1:

[0043] According to the data comparison between Examples 1-3 and Comparative Example 1, the high-functionality polyurethane acrylate prepared by using multifunctional active monomers can significantly improve the crosslinking density of the cured adhesive layer, which not only enhances the cohesive force and bulk strength, but also effectively improves the toughness, hardness, and surface drying properties, while improving the peeling effect and cutting processability.

[0044] The comparison results of Examples 1-3 and Comparative Example 2 show that the introduction of composite nano-toughening agent not only significantly enhances the toughness of the cured film, but also unexpectedly brings further optimization of strength, peel effect and cutting processability.

[0045] As can be seen from the comparison between Examples 1-3 and Comparative Example 3, the UV-curable temporary protective adhesive prepared by the present invention has better overall performance than commercially available superior products of the same type.

[0046] The UV-curable temporary protective adhesive prepared by this invention exhibits significantly superior flexibility, impact resistance, and surface drying effect compared to the control sample while maintaining rapid curing characteristics. Its peel force is moderate and stable, enabling clean peeling later. It successfully achieves a synergistic balance of high toughness, good surface drying, and peelability, resulting in overall performance that significantly surpasses existing similar products.

[0047] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-toughness UV-curable temporary protective adhesive, characterized in that, Including the following parts by weight of raw materials: 60-75 parts of polyurethane acrylate, 20-40 parts of reactive diluent 1-5 parts of photoinitiator Leveling agent 0.1-1 part, Defoamer 0.1-1 part, 0.5-5 parts of nano-toughening agent, 0.1-5 parts of silane coupling agent.

2. The high-toughness UV-curable temporary protective adhesive according to claim 1, characterized in that, The polyurethane acrylate is a polyurethane acrylate with a functionality of 2-4 and a molecular weight of 10,000-50,000; the polyurethane acrylate is a product of the reaction between isocyanate-terminated polyurethane prepolymer and acrylate monomer.

3. The high-toughness UV-curable temporary protective adhesive according to claim 2, characterized in that, The isocyanate-terminated polyurethane prepolymer is prepared by reacting isocyanate and diol at a molar ratio of isocyanate group to hydroxyl group of (1.0-1.5):

1.

4. The high-toughness UV-curable temporary protective adhesive according to claim 3, characterized in that, The isocyanate is one or a mixture of more of the following: hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, phenyldimethyl diisocyanate, toluene diisocyanate, and diphenylmethyl diisocyanate. The diol is one or more of polyether diol, polyester diol, and polycarbonate diol.

5. The high-toughness UV-curable temporary protective adhesive according to claim 4, characterized in that, The isocyanate is isophorone diisocyanate; The polyether diol includes one or more of the following: polyethylene oxide diol with an average molecular weight of 2000-4000, polypropylene glycol with an average molecular weight of 2000-6000, or polytetrahydrofuran with an average molecular weight of 2000-4000. The polyester diols include aromatic polyester polyols and aliphatic polyester polyols with an average molecular weight of 1000-5000. The polycarbonate diol includes, but is not limited to, polycarbonate diols with an average molecular weight of 2000-4000.

6. The high-toughness UV-curable temporary protective adhesive according to claim 2, characterized in that, The acrylate monomer is a compound of hydroxyl-containing acrylate monomer and hydroxyl-free acrylate.

7. The high-toughness UV-curable temporary protective adhesive according to claim 6, characterized in that, The hydroxyl-containing acrylate monomer is pentaerythritol triacrylate; The hydroxy-free acrylate monomer is one or more of trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and ethoxylated trimethylolpropane triacrylate.

8. The high-toughness UV-curable temporary protective adhesive according to claim 1, characterized in that, The photoinitiator is a free radical photoinitiator; The active diluent includes butylene(meth)acrylate, cyclohexyl(meth)acrylate, dicyclopentyl(meth)acrylate, dicyclopentenyl(meth)acrylate, dicyclopentenoxyethyl(meth)acrylate, N,N-diethylaminoethyl(meth)acrylate, 2-ethoxyethyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, caprolactone-modified 2-hydroxyethyl(meth)acrylate, isobornyl(meth)acrylate, lauryl(meth)acrylate, acryloylmorpholine, N-vinylcaprolactam, and nonyl... One or more of the following: phenoxy polyethylene glycol (meth)acrylate, nonylphenoxy polypropylene glycol (meth)acrylate, phenoxyethyl methacrylate, phenoxyhydroxypropyl methacrylate, phenoxydiglycol methacrylate, polyethylene glycol methacrylate, polypropylene glycol methacrylate, tetrahydrofurfuryl methacrylate, 1,6-hexanediol diacrylate, cyclotrimethylolpropane methyl acetal acrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and ethoxylated trimethylolpropane triacrylate; The nano-toughening agent is one or more of the following: nano-silica and / or nano-alumina, nano-rubber particles, and core-shell acrylate microspheres, whose surfaces are modified with organosilanes or acrylate monomers.

9. The method for preparing the high-toughness UV-curable temporary protective adhesive according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Synthesis of isocyanate-terminated polyurethane prepolymer: One or more of polyether diols, polyester diols, and polycarbonate diols are heated to 100℃~120℃ and stirred under vacuum to remove water for 2~3 hours, removing trace amounts of moisture; the dehydrated diol or diol mixture is cooled to 50-80℃, polyphosphoric acid is added and stirred for 10~30 minutes, then a measured amount of isocyanate and catalyst are added, and the reaction is stirred under vacuum. The NCO group content is monitored to reach the theoretical value of 0.7%-1.7%, thus obtaining the isocyanate-terminated polyurethane prepolymer; S2. Synthesis of polyurethane acrylate: Add a compound containing hydroxyl acrylate monomers and non-hydroxyl acrylate monomers to the polyurethane prepolymer with terminal isocyanate groups prepared in step S1 above, and react under the conditions of 70℃~80℃ and vacuum degree below 100Pa, so that the hydroxyl groups of the hydroxyl acrylate monomers react with the NCO groups at the end of the prepolymer to obtain the desired polyurethane acrylate. S3. Preparation of UV adhesive: Under light-protected conditions, the above-synthesized polyurethane acrylate, reactive diluent, photoinitiator, silane coupling agent, nano toughening agent, defoamer and leveling agent are added in sequence, and the mixture is stirred thoroughly until all components are evenly dispersed to obtain a high-toughness UV-curable temporary protective adhesive.

10. The method of using the high-toughness UV-curable temporary protective adhesive according to any one of claims 1-8, characterized in that, Includes the following steps: (I) Pre-treat the surface of the target substrate to thoroughly remove grease, fingerprints, dust, and mold release agent contaminants; (II) Inject the prepared adhesive into the spraying equipment and spray it evenly onto the cleaned target substrate surface; (III) After spraying, allow the adhesive layer to stand and level. Once the surface of the adhesive layer is smooth, use a UV-LED light source with a wavelength of 365 nm or 395 nm for irradiation and curing. The irradiation energy should be controlled within the range of 500–2000 mJ / cm². (IV) Once the curing is complete, the substrate with the protective adhesive layer can be transferred to the subsequent transport or processing procedures.

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