Anti-aging UV moisture dual-curing polyurethane adhesive and preparation method thereof

Abstract

The invention relates to an anti-aging UV moisture dual-curing polyurethane adhesive and a preparation method thereof, and belongs to the technical field of polyurethane adhesives, the polyurethane adhesive comprises polyester polyol, polyether polyol, polyisocyanate, a hydroxyl-containing acrylate monomer, a photoinitiator, an anti-aging auxiliary agent system, a silane coupling agent and a catalyst; the anti-aging additive system comprises an antioxidant, an ultraviolet absorbent and a light stabilizer; the weight ratio of the ultraviolet absorbent to the light stabilizer is 1: (2-3), and the weight ratio of the photoinitiator to the ultraviolet absorbent is (1.5-3): 1. The polyurethane adhesive has a UV and moisture dual-curing effect, realizes combination of rapid setting and deep strengthening, has good aging resistance, and enables an adhesive layer to maintain excellent mechanical properties and appearance for a long time under outdoor ultraviolet irradiation.

Description

Technical Field

[0001] This invention relates to an aging-resistant UV-curable moisture-curing polyurethane adhesive and its preparation method, belonging to the field of polyurethane adhesive technology. Background Technology

[0002] Reactive polyurethane adhesives (PURs) combine the rapid initial tack of traditional hot melt adhesives with the high final strength and durability of reactive adhesives, making them widely used in the automotive, electronics, textile, woodworking, and packaging industries. Their working principle is as follows: the adhesive matrix is ​​a polyurethane prepolymer with isocyanate-terminated (-NCO) groups. After being heated and melted for application, it reacts with moisture in the air, extending its chains and crosslinking to form a three-dimensional network structure, thus achieving excellent final bonding performance. However, traditional moisture-curing PURs have some inherent drawbacks: (1) Slow curing speed and greatly affected by the environment: Its curing depends on the ambient humidity. In low temperature and low humidity environment, the curing speed is extremely slow, which seriously affects the production efficiency. In high temperature and high humidity environment, the surface of the colloid is easy to react with moisture to form a skin, which hinders the entry of internal moisture, resulting in the phenomenon of "dry on the surface but not dry inside", which affects the final performance.

[0003] (2) Limited initial strength: Before it is fully cured, its initial adhesion and cohesion are relatively low, making it poorly adaptable to construction scenarios on vertical or facade surfaces that require rapid positioning.

[0004] (3) The aging resistance (especially the heat aging resistance and UV aging resistance) needs to be improved: the urethane bonds and ester bonds in polyurethane materials are prone to degradation under long-term heat, oxygen and ultraviolet radiation, resulting in yellowing, brittleness and reduced strength of the adhesive layer, which limits its application in high-end fields with weather resistance requirements such as outdoor products and automotive interiors.

[0005] To overcome the drawbacks of single moisture curing, a UV / moisture dual-curing system has been proposed in existing technologies. This system introduces UV-curable groups (such as acrylate groups) into the PUR prepolymer. After application, rapid initial curing (shaping) is achieved through UV irradiation, followed by moisture curing for deep curing and final high strength. For example, patent applications CN110885663A and CN110452655A disclose UV / moisture dual-curing hot melt adhesives. However, the UV / moisture dual-curing system also presents other problems, such as: (1) Competition and inhibition between UV curing and moisture curing: If the UV curing degree is too deep, the cross-linking network formed will seriously hinder the diffusion of subsequent moisture into the adhesive layer, resulting in the moisture curing reaction not being able to proceed fully, ultimately affecting the long-term durability and heat resistance of the adhesive layer.

[0006] (2) Balance of aging resistance: The introduced acrylate monomer or oligomer can reduce the heat resistance of the glue, and it can also be aged under ultraviolet light. How to balance the rapid curing and long-term aging resistance is a major challenge.

[0007] (3) Compatibility problem: Poor compatibility of UV curing components and polyurethane prepolymer can lead to poor storage stability and uneven performance.

[0008] Therefore, there is an urgent need in the art to develop a new type of UV moisture dual-curing polyurethane glue, which not only has the characteristics of rapid initial curing and high final strength, but also solves the synergy problem of dual curing mechanism, and significantly improves its heat aging resistance and ultraviolet aging resistance, to meet the needs of high-end application fields. SUMMARY

[0009] The present application provides a UV moisture dual-curing polyurethane glue with aging resistance and its preparation method, which has UV moisture dual-curing effect, realizes the combination of "rapid shaping" and "deep strengthening", and has good aging resistance, so that the glue layer can maintain excellent mechanical properties and appearance under outdoor ultraviolet radiation for a long time, and also maintain excellent mechanical properties and appearance state under heat aging.

[0010] The technical scheme for solving the above technical problems is as follows: a UV moisture dual-curing polyurethane glue with aging resistance, the polyurethane glue comprises: polyester polyol, polyether polyol, polyisocyanate, hydroxyl-containing acrylate monomer, photoinitiator, aging-resistant additive system, silane coupling agent and catalyst; The aging-resistant additive system comprises an antioxidant, an ultraviolet absorber and a light stabilizer; The weight ratio of the ultraviolet absorber and the light stabilizer is 1: (2-3), and the weight ratio of the photoinitiator and the ultraviolet absorber is (1.5-3): 1.

[0011] Further, the polyester polyol is 30-60 parts, the polyether polyol is 10-30 parts, the polyisocyanate is 10-25 parts, the acrylate monomer is 5-15 parts, the photoinitiator is 0.5-3 parts, the aging-resistant additive system is 1-5 parts, the silane coupling agent is 0.5-2 parts, and the catalyst is 0.01-0.1 parts by weight; In the aging-resistant additive system, the antioxidant is 0.2-0.5 parts; the ultraviolet absorber is 0.2-1.2 parts; and the light stabilizer is 0.6-3.6 parts.

[0012] Further, the polyester polyol is a polyester polyol obtained by polycondensation of aromatic dibasic acid or aromatic dibasic anhydride and aliphatic dihydric alcohol, with a number average molecular weight of 1000-3000 and a hydroxyl value of 50-110 mgKOH / g. The polyether polyol is a polyoxypropylene glycol with a number average molecular weight of 1000-2000.

[0013] Further, the polyisocyanate is at least one of 4,4'-diphenylmethane diisocyanate, liquefied MDI, isophorone diisocyanate.

[0014] Further, the hydroxyl-containing acrylate monomer is at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate.

[0015] Further, the photoinitiator is at least one of a free radical type photoinitiator.

[0016] Further, the antioxidant includes a hindered phenol antioxidant and a phosphite antioxidant; the weight ratio of the hindered phenol antioxidant and the phosphite antioxidant is 1: (1-2).

[0017] Further, the ultraviolet absorber is at least one of a benzotriazole type, a triazine type or a benzophenone type ultraviolet absorber. The light stabilizer is at least one of a hindered amine light stabilizer.

[0018] Further, the silane coupling agent is at least one of an epoxy group-containing or amino group-containing silane coupling agent. The catalyst is at least one of an organotin type catalyst, an organobismuth type catalyst, an amine type catalyst.

[0019] The application also discloses a preparation method of the aging-resistant UV moisture dual-curing polyurethane adhesive. S1, dehydration pretreatment: after mixing polyester polyol and polyether polyol, dehydration under heating and negative pressure is carried out until the water content is less than or equal to 0.03% under the condition of inert gas; S2, prepolymer synthesis: polyisocyanate and a catalyst are added to the system of step S1, and reaction is carried out under heating; S3, introduction of UV curing groups: after the reaction of step S2 is completed, the system temperature is controlled, a hydroxyl-containing acrylate monomer and a polymerization inhibitor are added, and reaction is carried out under insulation; S4, mixing and discharging: after the reaction of step S3 is completed, the system temperature is controlled, a photoinitiator, an aging-resistant auxiliary system and a silane coupling agent are added, and the polyurethane adhesive is obtained after mixing uniformly.

[0020] The application has the following beneficial effects: The application provides an anti-aging UV moisture dual-curing polyurethane adhesive, which realizes efficient cooperation of UV curing and moisture curing through formula design, guarantees rapid positioning strength after sizing, ensures deep moisture curing, finally endows the adhesive with excellent initial bonding strength, final bonding strength, and excellent heat aging resistance and ultraviolet aging resistance, and solves the balance problem of UV curing and aging resistance.

[0021] In the polyurethane adhesive, the hydroxyl-containing acrylate monomer is used as an end-capping agent to directly chemically bond the UV curing group to the polyurethane main chain, and the compatibility problem possibly caused by physical blending is solved. After UV irradiation, the acryloyloxy group is quickly crosslinked to form a primary network, providing instant initial curing strength; the primary network has a moderate crosslinking density and does not completely hinder the diffusion of moisture, so that the subsequent moisture curing reaction can be fully carried out to form a dense and strong final crosslinking network, realizing the combination of 'rapid shaping' and 'deep strengthening'.

[0022] In the polyurethane adhesive, aromatic polyester polyols synthesized from isophthalic acid and the like are selected as the main chain, the molecular chain has high rigidity and high heat distortion temperature. The anti-aging additive system can effectively inhibit the degradation of the polyurethane in a thermal oxygen environment, and significantly improves the long-term heat stability of the adhesive.

[0023] In the anti-aging additive system used in the application, the 'ultraviolet absorber + hindered amine light stabilizer' composite anti-aging system has good compatibility with the polyurethane matrix and can synergistically act to effectively absorb and quench ultraviolet energy, prevent the polymer chain from breaking and yellowing, and enable the adhesive layer to maintain excellent mechanical properties and appearance for a long time under outdoor ultraviolet irradiation.

[0024] In the polyurethane adhesive, the rigidity and toughness of the adhesive are balanced through the compounding of polyester / polyether polyols. The introduction of the silane coupling agent enhances the bonding force to various substrates (especially metals, glass and the like). The final product has high initial bonding strength, high final peel strength and shear strength, good temperature resistance and durability.

[0025] The preparation method of the polyurethane adhesive has mild and controllable conditions, ensures the smooth progress of the reaction and the stability of the product quality through stepwise feeding and accurate temperature control, and is simple in process and suitable for industrial large-scale production. DETAILED DESCRIPTION

[0026] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0028] An anti-aging UV moisture dual-curing polyurethane adhesive, comprising: polyester polyol, polyether polyol, polyisocyanate, hydroxyl-containing acrylate monomer, photoinitiator, anti-aging additive system, silane coupling agent and catalyst; The anti-aging additive system comprises antioxidant, ultraviolet absorber and light stabilizer; The weight ratio of the ultraviolet absorber and the light stabilizer is 1:(2-3), and the weight ratio of the photoinitiator and the ultraviolet absorber is (1.5-3):1.

[0029] When the weight ratio of the ultraviolet absorber and the light stabilizer is less than 1:2 (i.e. the proportion of the light stabilizer is reduced), the free radical quenching ability is insufficient to effectively prevent chain degradation; if the weight ratio of the ultraviolet absorber and the light stabilizer is higher than 1:3 (i.e. the proportion of the light stabilizer is increased), the weak alkalinity of the HALS (hindered amine light stabilizer) itself may have a potential impact on the storage stability of the polyurethane, and the cost-effectiveness is reduced. The weight ratio of the ultraviolet absorber and the light stabilizer is 1:(2-3), which ensures the best balance between "defense" and "repair", so that the polyurethane adhesive has better resistance to strength decay. In addition, the appropriate proportion of the photoinitiator and the ultraviolet absorber limits the good cooperation between the photocuring performance and the anti-aging performance, so that the polyurethane adhesive can not only achieve good UV moisture dual-curing performance, but also maintain good anti-aging performance.

[0030] Specifically, the polyester polyol is 30-60 parts, the polyether polyol is 10-30 parts, the polyisocyanate is 10-25 parts, the acrylate monomer is 5-15 parts, the photoinitiator is 0.5-3 parts, the anti-aging additive system is 1-5 parts, the silane coupling agent is 0.5-2 parts, and the catalyst is 0.01-0.1 part by weight; In the anti-aging additive system, the antioxidant is 0.2-0.5 parts; the ultraviolet absorber is 0.2-1.2 parts; and the light stabilizer is 0.6-3.6 parts.

[0031] Specifically, the polyester polyol is a polyester polyol obtained by polycondensation of an aromatic diacid or aromatic dianhydride with an aliphatic diol, with a number average molecular weight of 1000-3000 and a hydroxyl value of 50-110 mgKOH / g. Preferably, a mixture of isophthalic acid (IPA) and terephthalic acid (PTA) is used as the acid source to introduce rigid benzene ring structures and improve heat resistance.

[0032] Specifically, the polyether polyol is a polypropylene oxide glycol (PPG) with a number average molecular weight of 1000-2000, used to improve the flexibility of the colloid.

[0033] Specifically, the polyisocyanate is selected from at least one of 4,4'-diphenylmethane diisocyanate (MDI), liquid MDI, and isophorone diisocyanate (IPDI).

[0034] Specifically, the hydroxyl-containing acrylate monomer is selected from at least one of hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), and hydroxyethyl methacrylate (HEMA). This component is the key to connecting UV curing and moisture curing, with its hydroxyl group participating in the -NCO end-capping reaction to introduce UV-curable acrylate groups onto the polyurethane molecular chain.

[0035] Specifically, the photoinitiator is at least one of a free radical type photoinitiator. For example, α-hydroxy ketones, benzoyl formate, benzoin and its ethers, acyl phosphine oxides, etc.

[0036] Among them, α-hydroxy ketones: this type of photoinitiator has high activity and good thermal stability, and the specific compounds involved are: 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone. Common commercial examples: Irgacure 184, Irgacure 1173, Darocur 1173, Irgacure 2959, BP 184, etc.

[0037] Benzoyl formate: the specific compound involved is methyl benzoyl formate. Common commercial examples: Darocur MBF.

[0038] Benzoin and its ethers: the specific compounds involved are benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether. Common commercial examples: Vicure 10, Vicure 30.

[0039] Acyl phosphine oxides: This class of photoinitiators is suitable for longer wavelength UV light and has high efficiency. Specific compounds involved are 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. Common commercial examples: Lucirin TPO, Irgacure 819, BAPO.

[0040] Specifically, the antioxidant includes hindered phenol antioxidant and phosphite antioxidant; the weight ratio of the hindered phenol antioxidant (such as 1010, 1076) and phosphite antioxidant (such as 168) is 1: (1-2).

[0041] Specifically, the ultraviolet absorber is selected from at least one of benzotriazole, triazine or benzophenone ultraviolet absorber.

[0042] The ultraviolet absorber is selected from at least one of benzotriazole, triazine or benzophenone. Benzotriazole and triazine are preferred because of their good compatibility with polyurethane, low volatility and migration.

[0043] Benzotriazoles: This class of ultraviolet absorbers has strong absorption for UVB and part of UVA, and is the most commonly used type in polyurethane systems. Specific compounds involved: 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl) benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3,5'-dipentylphenyl) benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole. Common commercial examples: Tinuvin P (UV-P), Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 329, UV-326, UV-327, UV-329, UV-328.

[0044] Triazines: This class of UVA has high molecular weight, excellent extraction resistance, wide absorption band and excellent heat resistance. Specific compounds involved: 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxy-phenol, 2-(4,6-di(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-(octyloxy)phenol. Common commercial examples: Tinuvin 1577 FF, Cyasorb UV-1164.

[0045] Benzophenones: Specific compounds involved are 2-hydroxy-4-n-octyloxybenzophenone. Common commercial examples: Chimassorb 81, UV-531.

[0046] More preferably, the ultraviolet absorber is selected from at least one of the triazines. Because the triazine ultraviolet absorber can achieve strong absorption and long-term stability after synergizing with the HALS, it realizes intramolecular synergism and provides long-term anti-aging protection. In addition, the triazine ultraviolet absorber can achieve protection effect at a lower concentration, reducing the total amount of photons competing with the photoinitiator, so that the polyurethane adhesive can achieve deep curing and good weather resistance.

[0047] More preferably, the ultraviolet absorber is selected from at least one of the triazines, and the photoinitiator is selected from at least one of the acyl phosphine oxide type. Because the absorption wavelength range of the acyl phosphine oxide type photoinitiator is less interfered with the strong absorption wavelength range of the triazine ultraviolet absorber, and the appropriate dosage ratio is matched, the polyurethane adhesive can simultaneously consider deep curing and anti-aging performance.

[0048] Specifically, the light stabilizer is selected from at least one of the hindered amine light stabilizers, which plays a role by capturing free radicals, and has excellent synergistic effect with the ultraviolet absorber.

[0049] The specific compound types and examples involved are as follows: Low molecular weight type: such as bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, a polymer of succinic acid and (2,2,6,6-tetramethyl-4-piperidyl) ethanol.

[0050] High molecular weight type: such as poly{[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidyl)imino]}, a polymer of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexanediamine, 2,4,6-trichloro-1,3,5-triazine, and N-butyl-1-butylamine and N-butyl-2,2,6,6-tetramethyl-4-piperidylamine.

[0051] Among them, the hindered amine light stabilizer of high molecular weight type is more preferred because of its low migration.

[0052] Common commercial brand examples: Tinuvin 770, Tinuvin 292, Chimassorb 944, Tinuvin 622, Cyasorb UV-3346, GW-770, GW-622, etc.

[0053] Specifically, the silane coupling agent is at least one of an epoxy group-containing or amino group-containing silane coupling agent; such as gamma-glycidoxypropyltrimethoxysilane (KH-560), gamma-aminopropyltriethoxysilane (KH-550), which is used to improve the adhesion to inorganic substrates (such as glass, metal).

[0054] The catalyst is at least one of an organic tin catalyst (such as dibutyltin dilaurate (DBTDL)), an organic bismuth catalyst, and an amine catalyst.

[0055] The application further discloses a preparation method of the anti-aging UV moisture dual-curing polyurethane adhesive. S1, dehydration pretreatment: after mixing polyester polyol and polyether polyol, dehydration is carried out under heating and negative pressure in an inert gas condition until the water content is less than or equal to 0.03% by mass; S2, prepolymer synthesis: polyisocyanate and a catalyst are added to the system of step S1, and reaction is carried out under heating; S3, introduction of UV curing groups: after the reaction of step S2 is completed, the system temperature is controlled, hydroxyl-containing acrylate monomers and a polymerization inhibitor are added, and reaction is carried out under insulation; S4, mixing and discharging: after the reaction of step S3 is completed, the system temperature is controlled, a photoinitiator, an anti-aging auxiliary system and a silane coupling agent are added, and uniform mixing is carried out to obtain the polyurethane adhesive.

[0056] More specifically, the preparation method is: S1, dehydration pretreatment: under nitrogen protection, polyester polyol and polyether polyol are added to a reaction kettle, heated to 120-140 DEG C, and dehydrated under a vacuum degree of -0.095 to -0.098 MPa for 2-3 hours until the water content is less than or equal to 0.03% by mass.

[0057] S2, prepolymer synthesis: the system is cooled to 80-100 DEG C, the vacuum is removed, a metered amount of polyisocyanate and a catalyst are added, the system is slowly heated to 110-120 DEG C under nitrogen protection, and reaction is carried out for 2-4 hours, during which the content of -NCO in the system is monitored.

[0058] S3, introduction of UV curing groups: when the content of -NCO reaches the theoretical value, the system is cooled to 50-60 DEG C, a metered amount of (methyl) acrylate monomer containing a hydroxyl group and an appropriate amount of a polymerization inhibitor (such as hydroquinone, the addition amount is 50-200 ppm) are added, and reaction is carried out under insulation at this temperature for 1-2 hours, so that the remaining -NCO and the hydroxyl group are fully reacted, and acryloyloxy is grafted to the polyurethane molecular chain.

[0059] S4, mixing and discharging: the system is cooled to 40-50℃ again, the photoinitiator, the anti-aging additive system and the silane coupling agent are added, and high-speed stirring is carried out for 0.5-1 hour to ensure that the components are fully mixed and uniform. Subsequently, the product is poured into a preheated container under nitrogen protection, and is stored in a sealed manner.

[0060] Example 1 A preparation method of an anti-aging UV moisture dual-curing polyurethane adhesive is as follows: According to the weight parts, the raw material formula is composed of: Polyester polyol (polycondensation of IPA, PTA and ethylene glycol, 1,4-butanediol, Mn=2000, hydroxyl value is 56 mgKOH / g): 45 parts; Polyether polyol (PPG-2000): 20 parts; 4,4'-diphenyl methane diisocyanate (MDI): 18 parts; Hydroxyethyl acrylate (HEA): 10 parts; Photoinitiator Irgacure 184: 1.5 parts; Antioxidant 1010: 0.1 part, antioxidant 168: 0.2 part; Ultraviolet absorber UV-329: 0.8 part; Light stabilizer HALS-944 (Chimassorb 944): 1.6 parts; Silane coupling agent KH-560: 1 part; Catalyst dibutyltin dilaurate (DBTDL): 0.03 parts; Polymerization inhibitor hydroquinone: 100 ppm (relative to the total mass of the polyurethane adhesive).

[0061] The polyurethane adhesive is prepared according to the above formula amount, and the specific preparation method is as follows: The polyester polyol and the polyether polyol are added to a reactor with stirring, nitrogen inlet, thermometer and vacuum system, and heated to 130℃ under nitrogen protection. Under the condition of -0.097 MPa vacuum, dehydration is carried out for 2.5 hours until the water content is ≤0.03%.

[0062] Cool to 95℃, remove the vacuum, add MDI and DBTDL, slowly warm to 85℃ and react for 3 hours, monitor the -NCO content to reach the theoretical value (-NCO content in the system is 3.4%-3.6%).

[0063] Cool to 55℃, add HEA and hydroquinone, and react for 1.5 hours.

[0064] Cool to 45℃, add photoinitiator 184, antioxidant 1010, antioxidant 168, UV-329, HALS-944 and KH-560, high-speed stirring for 40 minutes, to obtain polyurethane glue.

[0065] The obtained light yellow viscous liquid was poured into an aluminum foil bag under nitrogen protection, sealed and stored in the dark.

[0066] Example 2 A preparation method of an aging-resistant UV moisture dual-curing polyurethane adhesive is as follows: According to the weight fraction, the raw material formula is composed of: Polyester polyol (polycondensation of PTA and 1,6-hexanediol, Mn=1500, hydroxyl value is 75 mgKOH / g): 55 parts; Polyether polyol (PPG-1000): 15 parts; Isophorone diisocyanate (IPDI): 22 parts; Hydroxyethyl methacrylate (HEMA): 8 parts; Photoinitiator Irgacure 1173: 2 parts; Antioxidant 1076: 0.15 parts, antioxidant 168: 0.3 parts; Ultraviolet absorber UV-327: 1 part; Light stabilizer HALS-622 (Tinuvin 622): 3 parts; Silane coupling agent KH-550: 1.5 parts; Catalyst organic bismuth: 0.05 parts; Polymerization inhibitor hydroquinone: 150 ppm (relative to the total mass of the polyurethane adhesive).

[0067] The polyurethane adhesive is prepared according to the above formula amount, and the specific preparation method is as follows: The preparation method is the same as that of Example 1, except that the corresponding raw materials are replaced by the raw materials in this embodiment.

[0068] Example 3 A preparation method of an aging-resistant UV moisture dual-curing polyurethane adhesive is as follows: According to the weight fraction, the raw material formula is composed of: Polyester polyol (polycondensation of PTA and 1,6-hexanediol, Mn=1500, hydroxyl value is 75 mgKOH / g): 60 parts; Polyether polyol (PPG-2000): 30 parts; Liquefied MDI: 25 parts; Hydroxyethyl methacrylate (HPA): 8 parts; Photoinitiator Darocur MBF: 3 parts; Antioxidant 1076: 0.25 parts, antioxidant 168: 0.25 parts; UV absorber UV-531: 1.2 parts; Light stabilizer HALS-622 (Tinuvin 622): 3.3 parts; Silane coupling agent KH-560: 2 parts; Catalyst dibutyltin dilaurate (DBTDL): 0.1 part; Polymerization inhibitor hydroquinone: 200 ppm (relative to the total mass of the polyurethane adhesive).

[0069] The polyurethane adhesive was prepared according to the above formulation amount, and the specific preparation method was as follows: The preparation method was the same as that of Example 1, except that the corresponding raw materials were replaced by the raw materials in this example.

[0070] Example 4 A preparation method of an aging-resistant UV-moisture dual-curing polyurethane adhesive was as follows: The raw material formulation consisted of, by weight fraction: Polyester polyol (polycondensed from IPA, PTA, ethylene glycol, and 1,4-butanediol; Mn = 2000, hydroxyl value of 56 mgKOH / g): 45 parts; Polyether polyol (PPG-2000): 20 parts; 4,4'-diphenyl methane diisocyanate (MDI): 18 parts; Hydroxyethyl acrylate (HEA): 10 parts; Photoinitiator BAPO: 1.5 parts; Antioxidant 1010: 0.1 part, antioxidant 168: 0.2 part; UV absorber Cyasorb UV-1164: 0.8 parts; Light stabilizer HALS-944 (Chimassorb 944): 1.6 parts; Silane coupling agent KH-560: 1 part; Catalyst dibutyltin dilaurate (DBTDL): 0.03 part; Polymerization inhibitor hydroquinone: 100 ppm (relative to the total mass of the polyurethane adhesive).

[0071] The polyurethane adhesive was prepared according to the above formulation amount, and the specific preparation method was as follows: The preparation method was the same as that of Example 1, except that the corresponding raw materials were replaced by the raw materials in this example.

[0072] Example 5 A preparation method of an aging-resistant UV-moisture dual-curing polyurethane adhesive was as follows: The raw material formula comprises, by weight: Polyester polyol (polycondensation of PTA and 1,6-hexanediol, Mn=1500, hydroxyl value 75 mgKOH / g): 55 parts; Polyether polyol (PPG-1000): 15 parts; Isophorone diisocyanate (IPDI): 22 parts; Hydroxyethyl methacrylate (HEMA): 8 parts; Photoinitiator Lucirin TPO: 2 parts; Antioxidant 1076: 0.15 parts, antioxidant 168: 0.3 parts; Ultraviolet absorber Tinuvin 1577 FF: 1 part; Light stabilizer HALS-622 (Tinuvin 622): 3 parts; Silane coupling agent KH-550: 1.5 parts; Catalyst organic bismuth: 0.05 parts; Polymerization inhibitor hydroquinone: 150 ppm (relative to the total mass of the polyurethane adhesive).

[0073] The polyurethane adhesive is prepared according to the above formula amount, and the specific preparation method is as follows: The preparation method is the same as that in Example 1, except that the corresponding raw materials are replaced by the raw materials in this example.

[0074] Comparative Example 1 The polyurethane adhesive is prepared by the same method as in Example 1, except that the UV curing component is not contained in this comparative example 1, i.e. hydroxyethyl acrylate (HEA) and photoinitiator 184 are not added in the formula, and the amount of MDI is adjusted accordingly to make the -NCO content the same as in the example, i.e. a moisture-cured PUR is prepared.

[0075] Comparative Example 2 The polyurethane adhesive is prepared by the same method as in Example 1, except that the anti-aging additive system is not contained in this comparative example 2, i.e. antioxidants, ultraviolet absorbers and light stabilizers are not added in the formula.

[0076] Comparative Example 3 The polyurethane adhesive is prepared by the same method as in Example 1, except that the weight ratio of ultraviolet absorber and light stabilizer in this comparative example 3 is 1:1 (not within the range of 1:(2-3) defined in the present application), i.e. the addition amount of ultraviolet absorber UV-329 in this comparative example 3 is 1.2 parts by weight; the addition amount of light stabilizer HALS-944 (Chimassorb 944) is 1.2 parts by weight.

[0077] Comparative Example 4 The polyurethane adhesive was prepared by the same method as in Example 1, except that the weight ratio of the UV absorber and the light stabilizer in Comparative Example 4 was 1:4 (not within the range of 1:(2-3) defined in the present application), i.e. the amount of the UV absorber UV-329 added in Comparative Example 4 was 0.48 parts by weight, and the amount of the light stabilizer HALS-944 (Chimassorb 944) added was 1.92 parts by weight.

[0078] Comparative Example 5 The polyurethane adhesive was prepared by the same method as in Example 1, except that the weight ratio of the photoinitiator and the UV absorber in Comparative Example 5 was 1:1 (not within the range of (1.5-3):1 defined in the present application), i.e. the amount of the photoinitiator Irgacure 184 added in Comparative Example 5 was 0.8 parts by weight.

[0079] Comparative Example 6 The polyurethane adhesive was prepared by the same method as in Example 1, except that the weight ratio of the photoinitiator and the UV absorber in Comparative Example 6 was 5:1 (not within the range of (1.5-3):1 defined in the present application), i.e. the amount of the photoinitiator Irgacure 184 added in Comparative Example 6 was 4 parts by weight.

[0080] The polyurethane adhesives prepared in the above examples and comparative examples were subjected to performance tests, and the specific test results are shown in Table 1 below, and the test methods involved are as follows: (1) Initial viscosity and open time: measured at 110°C in a molten state.

[0081] (2) Initial adhesive strength after UV curing: the adhesive was coated on an aluminum sheet, and the tensile strength was tested immediately after UV irradiation (80W / cm high-pressure mercury lamp, irradiation distance 10cm, time 5s).

[0082] (3) Final adhesive strength: after the adhesive was applied and UV irradiated, the final tensile strength was tested after curing at 23°C and 50% relative humidity for 7 days (the thickness of the coated adhesive was 0.2mm).

[0083] (4) Heat aging resistance: the cured sample was placed in an oven at 80°C, and after aging for 240 hours, the tensile shear strength retention rate was tested.

[0084] (5) UV aging resistance: the cured sample was placed in a UV aging box (UVA-340 lamp, 60°C, irradiance 0.68W / m²), and after irradiation for 500 hours, the appearance change (degree of yellowing) was observed and the tensile shear strength retention rate was tested.

[0085] Table 1 Performance test results From the above table data, it can be seen that the polyurethane adhesive prepared by the preparation method of the application in Examples 1-5 has UV and moisture dual curing effect, and can quickly obtain high initial adhesive strength after UV irradiation, which is much higher than that of traditional PUR (0.1 MPa), greatly facilitating the rapid positioning of the workpiece. At the same time, its final strength is also better than that of traditional PUR (Comparative Example 1), indicating that the dual curing synergistic effect is good, realizing the combination of "rapid shaping" and "deep strengthening", and having good aging resistance, so that the adhesive layer can maintain excellent mechanical properties and appearance under outdoor ultraviolet irradiation for a long time, and also maintain excellent mechanical properties and appearance state under heat aging conditions. In addition, from the comparison of the results of Example 1 and Example 4, and the comparison of the results of Example 2 and Example 5, it can be seen that when the ultraviolet absorber is selected from triazine and the photoinitiator is selected from acyl phosphine oxide, the comprehensive performance of the polyurethane adhesive is more excellent, because the absorption band of the acyl phosphine oxide photoinitiator is less interfered with the strong absorption band of the triazine ultraviolet absorber, and the appropriate dosage ratio is matched, so that the polyurethane adhesive simultaneously considers deep curing and aging resistance.

[0086] From the comparison of the experimental results of Comparative Example 2 and Example 1, it can be seen that the aging resistance aid system of the application plays a key role. After heat aging and ultraviolet aging, the strength retention rate of Example 1 (92%, 88%) is much higher than that of Comparative Example 2 (58%, 52%), which proves that the aid system effectively delays the aging degradation of the polyurethane material and significantly improves the durability of the product.

[0087] From the comparison of the experimental results of Comparative Example 3, Comparative Example 4 and Example 1, it can be seen that when the weight ratio of ultraviolet absorber to light stabilizer is 1:(2-3), it is more conducive to obtaining polyurethane adhesive with excellent comprehensive performance. When the weight ratio of ultraviolet absorber to light stabilizer is less than 1:2 (i.e. the dosage ratio of light stabilizer is reduced), the free radical quenching ability is insufficient to effectively prevent chain degradation. If the weight ratio of ultraviolet absorber to light stabilizer is higher than 1:3 (i.e. the dosage ratio of light stabilizer is increased), the weak alkalinity of HALS (hindered amine light stabilizer) itself may have a potential impact on the storage stability of polyurethane, and the cost-effectiveness is reduced. The weight ratio of ultraviolet absorber to light stabilizer of 1:(2-3) ensures the best balance between "defense" and "repair", so that the polyurethane adhesive has better resistance to strength decay.

[0088] From the comparison of the experimental results of Comparative Example 5, Comparative Example 6 and Example 1, it can be seen that the appropriate ratio of photoinitiator to ultraviolet absorber limits the good matching relationship between the photocuring performance and the aging resistance, so that the polyurethane adhesive can not only achieve good UV and moisture dual curing performance, but also maintain good aging resistance.

[0089] In summary, the UV curing process is a fast process (short term, high energy) that is completed within tens of seconds after the application of the glue. Its energy source is a high intensity, specific wavelength (mainly around 365 nm) UV lamp. This process requires a sufficient amount of UV photons to quickly penetrate the glue layer, be absorbed by the photoinitiator, and generate enough free radicals to initiate the rapid polymerization of the acrylate double bonds.

[0090] The aging resistant protection process refers to the process in which the product resists outdoor natural light aging during its service period (which can be up to several years) (long term, low energy). Its energy source is continuous, full-spectrum, relatively much lower intensity natural sunlight, especially the destructive UVA / UVB band (280-400 nm) therein. The role of the ultraviolet light absorber and the light stabilizer is to continuously absorb or quench these low-energy ultraviolet light and prevent its destruction to the polymer main chain (such as polyurethane bonds, ester bonds) on this long time scale.

[0091] The present application ensures that, by selecting the appropriate type and amount of aging resistant auxiliary agent, and utilizing the high intensity of the UV curing light source, there are enough photons to "break through" the weak shielding effect of the auxiliary agent within the short UV irradiation window, efficiently triggering the curing; and in the subsequent long service period, these auxiliary agents can play a strong protective role, thereby obtaining an aging resistant UV moisture dual-cured polyurethane glue.

[0092] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure.

[0093] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. An aging-resistant UV-curable and moisture-resistant dual-curing polyurethane adhesive, characterized in that, The polyurethane adhesive comprises: polyester polyol, polyether polyol, polyisocyanate, hydroxyl-containing acrylate monomer, photoinitiator, anti-aging additive system, silane coupling agent and catalyst; The anti-aging additive system includes antioxidants, ultraviolet absorbers, and light stabilizers; The weight ratio of the ultraviolet absorber to the light stabilizer is 1:(2-3), and the weight ratio of the photoinitiator to the ultraviolet absorber is (1.5-3):

1.

2. The UV-curable and moisture-resistant dual-curing polyurethane adhesive according to claim 1, characterized in that, By weight, the composition includes 30-60 parts polyester polyol, 10-30 parts polyether polyol, 10-25 parts polyisocyanate, 5-15 parts acrylate monomer, 0.5-3 parts photoinitiator, 1-5 parts anti-aging additive system, 0.5-2 parts silane coupling agent, and 0.01-0.1 parts catalyst. In the anti-aging additive system, the antioxidant is 0.2-0.5 parts; the ultraviolet absorber is 0.2-1.2 parts; Light stabilizer 0.6-3.6 parts.

3. The UV-curable and moisture-resistant dual-curing polyurethane adhesive according to claim 1, characterized in that, The polyester polyol is a polyester polyol obtained by polycondensation of aromatic diacid or aromatic diacid anhydride with aliphatic diol, with a number average molecular weight of 1000-3000 and a hydroxyl value of 50-110 mgKOH / g. The polyether polyol is polyoxypropylene glycol with a number average molecular weight of 1000-2000.

4. The UV-curable and moisture-resistant dual-curing polyurethane adhesive according to claim 1, characterized in that, The polyisocyanate is selected from at least one of 4,4'-diphenylmethane diisocyanate, liquefied MDI, and isophorone diisocyanate.

5. The UV-curable and moisture-resistant dual-curing polyurethane adhesive according to claim 1, characterized in that, The hydroxyl-containing acrylate monomer is selected from at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxyethyl methacrylate.

6. The UV-curable and moisture-resistant dual-curing polyurethane adhesive according to claim 1, characterized in that, The photoinitiator is at least one of the free radical photoinitiators.

7. The UV-curable and moisture-resistant dual-curing polyurethane adhesive according to claim 1, characterized in that, The antioxidants include hindered phenolic antioxidants and phosphite antioxidants; the weight ratio of the hindered phenolic antioxidants to the phosphite antioxidants is 1:(1-2).

8. The UV-curable and moisture-resistant dual-curing polyurethane adhesive according to claim 1, characterized in that, The ultraviolet absorber is selected from at least one of benzotriazole, triazine, or benzophenone ultraviolet absorbers; The light stabilizer is selected from at least one of hindered amine light stabilizers.

9. The UV-curable and moisture-resistant dual-curing polyurethane adhesive according to claim 1, characterized in that, The silane coupling agent is at least one of the silane coupling agents containing epoxy groups or amino groups; The catalyst is at least one of organotin catalysts, organobismuth catalysts, and amine catalysts.

10. A method for preparing an aging-resistant UV-moisture dual-curing polyurethane adhesive according to any one of claims 1-9, characterized in that, The preparation method is as follows: S1. Dehydration pretreatment: Under inert gas conditions, polyester polyol and polyether polyol are mixed and then heated and dehydrated under negative pressure until the moisture content is ≤0.03% by mass. S2, Prepolymer Synthesis: Polyisocyanate and catalyst are added to the system of step S1, and the reaction is carried out under heating conditions; S3. Introducing UV-curable groups: After the reaction in step S2 is completed, control the system temperature, add hydroxyl-containing acrylate monomers and polymerization inhibitors, and keep the temperature to carry out the reaction. S4. Mixing and Discharging: After the reaction in step S3 is completed, control the system temperature, add the photoinitiator, anti-aging additive system and silane coupling agent, and mix evenly to obtain the polyurethane adhesive.

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