Polyurethane adhesive and application thereof in compounding of PET (Polyethylene Terephthalate) membrane material and PET foam board

Abstract

The invention belongs to the technical field of adhesives, and particularly relates to a polyurethane adhesive and application thereof in compounding of a PET (Polyethylene Terephthalate) film material and a PET foam board. The polyurethane adhesive provided by the invention comprises a component A and a component B which are independently packaged, the component A comprises polyester polyol, polycarbonate polyol, castor oil, an auxiliary agent and an organic solvent, and the mass ratio of the polyester polyol to the polycarbonate polyol to the castor oil to the auxiliary agent to the organic solvent is (50-70): (5-15): (2-10): (0-8): (15-35); and the component B is an isocyanate compound, and the content of isocyanato in isocyanate is 15-35%. The polyurethane adhesive provided by the invention can be suitable for composite bonding of a PET (Polyethylene Terephthalate) film material and a PET foam board, and has excellent bonding strength and humidity and heat resistance; meanwhile, the curing speed and the working life are balanced, and environmental protection and construction efficiency are both considered.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a polyurethane adhesive and its application in PET film-PET foam board composite. Background Technology

[0002] PET film and PET foam are widely used in building decoration, automotive interiors, packaging materials, and new energy fields due to their excellent mechanical properties, chemical resistance, and lightweight characteristics. The composite bonding of these two materials is significant in improving their overall performance, such as strength, lightweight, and weather resistance. However, the low surface energy, low polarity, and high crystallinity of PET film make it difficult for traditional adhesives to wet and penetrate, resulting in significant bonding challenges. The porous structure of PET foam further complicates and increases the difficulty of bonding.

[0003] Traditional adhesives such as solvent-based acrylates or epoxy resins suffer from slow curing speeds and insufficient weather resistance, making them unsuitable for current applications. Polyurethane adhesives, due to their highly designable molecular chains and excellent bonding properties, are gradually becoming the preferred choice for PET lamination. However, traditional polyurethane adhesives still have limitations. For example, PET is difficult to wet and penetrate, leading to insufficient adhesion and easy delamination; even after physical treatment, the strength of PET remains unsatisfactory. They also have insufficient resistance to humid heat aging, easily undergoing hydrolysis in high-temperature and high-humidity environments, resulting in weakened bond strength. Furthermore, they exhibit low curing efficiency or low cured strength at room temperature.

[0004] Currently, most related technologies address the bonding issues between PET and non-PET materials. However, when it comes to the composite bonding of PET film and PET foam board, the following problems still exist: First, the interface compatibility is insufficient. Existing adhesives cannot simultaneously meet the requirements of the low surface energy of PET film and the porous structure of foam board, resulting in poor bonding strength and resistance to damp heat, which cannot be achieved simultaneously. Summary of the Invention

[0005] The purpose of this invention is to provide a polyurethane adhesive and its application in the composite bonding of PET film and PET foam board. The polyurethane adhesive provided by this invention is suitable for the composite bonding of PET film and PET foam board, and has excellent bonding strength and resistance to damp heat; at the same time, it balances the curing speed and pot life, taking into account both environmental protection and construction efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a polyurethane adhesive comprising individually packaged component A and component B;

[0008] Component A comprises polyester polyol, polycarbonate polyol, castor oil, additives, and organic solvents. The number average molecular weight of the polyester polyol is ≥4500. The mass ratio of the polyester polyol to the polycarbonate polyol is (50-70):(5-15), the mass ratio of the polyester polyol to the castor oil is (50-70):(2-10), the mass ratio of the polyester polyol to the additives is (50-70):(0-8), and the mass ratio of the polyester polyol to the organic solvent is (50-70):(15-35).

[0009] Component B is an isocyanate compound, and the isocyanate content of the isocyanate compound is 15-35%.

[0010] Preferably, the molar ratio of isocyanate group in component B to hydroxyl group in component A is 1 to 1.5:1.

[0011] Preferably, the number-average molecular weight of the polyester polyol is 4500-8500, and the hydroxyl value is 10-35 mg KOH / g;

[0012] The polycarbonate polyol has a number-average molecular weight of 500–4000 and a hydroxyl value of 28–250 mg KOH / g;

[0013] The additives include one or more of catalysts, silane coupling agents, and tackifying resins;

[0014] The organic solvent includes one or more of ethyl acetate, butyl acetate, acetone, propylene glycol methyl ether acetate, and dimethyl carbonate.

[0015] Preferably, the method for preparing the polycarbonate polyol includes: subjecting a diol and dimethyl carbonate to an ester exchange reaction to obtain the polycarbonate polyol;

[0016] The diol includes at least two of 1,6-hexanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,4-pentanediol, and 1,4-cyclohexanediol.

[0017] Preferably, the catalyst comprises one or more of bismuth octanoate, zinc neodecanoate, dimethylcyclohexylamine, triethylenediamine, stannous octanoate, dioctyltin dilaurate, and dibutyltin dilaurate, wherein the mass percentage of the catalyst relative to the mass of component A is ≤0.5%.

[0018] The silane coupling agent includes one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and the mass percentage of the silane coupling agent to the mass of component A is ≤4%.

[0019] The tackifying resin is an epoxy resin, and the mass percentage of the tackifying resin in component A is ≤8%.

[0020] Preferably, the preparation method of component A includes the following steps:

[0021] In a protective gas atmosphere, the polyester polyol, polycarbonate polyol and castor oil are heated, then vacuumed and kept at that temperature. After a period of time, additives are added and the reaction continues. Finally, an organic solvent is added and mixed while the mixture is cooled to obtain component A. The water content of component A is ≤300ppm.

[0022] Preferably, the isocyanate compound includes one or more of polymethylene polyphenyl polyisocyanate, carbodiimide-modified MDI, hexamethylene diisocyanate trimer, and isophorone diisocyanate trimer.

[0023] This invention provides the application of the polyurethane adhesive described in the above technical solution in the composite of PET film and PET foam board.

[0024] Preferably, the application includes the following steps:

[0025] The components A and B are mixed to obtain a colloid solution;

[0026] The adhesive is applied to the bonding surface of the PET foam board, and after solvent removal, it is laminated with the PET film material.

[0027] Preferably, the viscosity of the adhesive solution at 25°C is 800–1500 mPa·s;

[0028] The solvent removal temperature is 90–120°C, and the time is 2–6 min;

[0029] The compounding process includes sequential pressing and curing, wherein the curing temperature is 20–60°C and the time is 24–72 h.

[0030] This invention provides a polyurethane adhesive comprising separately packaged components A and B. Component A includes polyester polyol, polycarbonate polyol, castor oil, additives, and an organic solvent. The number average molecular weight of the polyester polyol is ≥4500. The mass ratio of the polyester polyol to the polycarbonate polyol is (50-70):(5-15), the mass ratio of the polyester polyol to the castor oil is (50-70):(2-10), the mass ratio of the polyester polyol to the additives is (50-70):(0-8), and the mass ratio of the polyester polyol to the organic solvent is (50-70):(15-35). Component B is an isocyanate compound with an isocyanate content of 15-35%. Due to the low surface energy of PET film and the complex structure of PET foam board, adhesion may be weak. The polyurethane adhesive provided by this invention exhibits high initial tack and good wetting properties. In the polyurethane adhesive provided by this invention, component A contains: compared to polyether polyols, the polar ester structure of polyester polyols results in better adhesion and stronger bonding to PET materials. Simultaneously, the high molecular weight of polyester polyols can form an elastic buffer band in the crosslinking network, preventing interfacial cracking caused by the brittleness of the PET foam board. Polycarbonate polyols possess excellent hydrolysis and weather resistance. The interfacial bonding strength of the polyester polyol and polycarbonate polyol blend system is greater than that of a single polyester system, and it can also improve the bonding strength after damp heat aging. Furthermore, polycarbonate polyols have stronger polarity and lower surface tension; their addition can improve the wettability of the adhesive to the PET film material, reduce defects during coating, and enhance initial adhesion. Furthermore, the addition of castor oil to component A can further and effectively reduce the surface tension of the adhesive system, promote its spreading on the surface of PET film and foam board, reduce coating defects, and improve initial adhesion. At the same time, it can work synergistically with additives to further enhance the bonding strength and improve the resistance to damp heat aging. In addition, since castor oil is a bio-renewable resource and a food-grade raw material, it can reduce the use of petroleum-based solvents and plasticizers in the formulation, reduce the VOC content of the system, and conform to the green recycling trend of PET materials.

[0031] Furthermore, the B component of the polyurethane adhesive provided by this invention is preferably polyisocyanate (polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate trimer, isophorone diisocyanate trimer) and / or carbodiimide-modified MDI. This invention uses polyisocyanate and / or carbodiimide-modified MDI as the B component of the polyurethane adhesive, which has low volatility. This can reduce the content of free monomers in the polyurethane adhesive system used for PET film-PET foam board composites, reduce inhalation toxicity and operational risks, and meet stricter environmental and safety standards, such as low VOC emissions.

[0032] In summary, the polyurethane adhesive provided by this invention belongs to the polyester-polycarbonate structural system, contains bio-based polyols, is safe and environmentally friendly, has excellent bonding performance, can be cured at room temperature, has a long pot life, and its viscosity is within 2800 mpa·s after mixing for 3 hours at 25°C. It can still work normally after being boiled in water at 100°C. Detailed Implementation

[0033] This invention provides a polyurethane adhesive comprising individually packaged component A and component B;

[0034] Component A comprises polyester polyol, polycarbonate polyol, castor oil, additives, and organic solvents. The number average molecular weight of the polyester polyol is ≥4500. The mass ratio of the polyester polyol to the polycarbonate polyol is (50-70):(5-15), the mass ratio of the polyester polyol to the castor oil is (50-70):(2-10), the mass ratio of the polyester polyol to the additives is (50-70):(0-8), and the mass ratio of the polyester polyol to the organic solvent is (50-70):(15-35).

[0035] Component B is an isocyanate compound, and the isocyanate content of the isocyanate compound is 15-35%.

[0036] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0037] The polyurethane adhesive provided by this invention comprises an individually packaged component A. Component A comprises polyester polyol, polycarbonate polyol, castor oil, additives, and an organic solvent. The number average molecular weight of the polyester polyol is ≥4500. The mass ratio of the polyester polyol to the polycarbonate polyol is (50-70):(5-15), the mass ratio of the polyester polyol to the castor oil is (50-70):(2-10), the mass ratio of the polyester polyol to the additives is (50-70):(0-8), and the mass ratio of the polyester polyol to the organic solvent is (50-70):(15-35).

[0038] In this invention, the number-average molecular weight of the polyester polyol is preferably 4500-8500, more preferably 5000-8500, and even more preferably 5500-7000. The hydroxyl value of the polyester polyol is preferably 10-35 mg KOH / g, more preferably 15-30 mg KOH / g. In a specific embodiment of this invention, the polyester polyol is an H-series hydrolysis-resistant polyester polyol purchased from Shanghai Shuyu Chemical Co., Ltd., which has high initial strength and good hydrolysis and temperature resistance. In a specific embodiment of this invention, the polyester polyol can be a polyester polyol product with the brand name H3022 or H3020 produced by Shanghai Shuyu Chemical Co., Ltd.

[0039] In this invention, the number average molecular weight of the polycarbonate polyol is preferably 500-4000, more preferably 800-2000, and in the examples it can be 900-1000. The hydroxyl value of the polycarbonate polyol is preferably 28-250 mg KOH / g, more preferably 50-150 mg KOH / g, and in the examples it can be 115-135 mg KOH / g.

[0040] In this invention, the method for preparing the polycarbonate polyol preferably includes: subjecting a diol and dimethyl carbonate to an ester exchange reaction to obtain the polycarbonate polyol. In this invention, the diol preferably includes at least two selected from 1,6-hexanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,4-pentanediol, and 1,4-cyclohexanediethanol, more preferably two selected from 1,6-hexanediol, 1,4-butanediol, 1,5-pentanediol, and 1,4-cyclohexanediethanol. In the examples, it can be 1,6-hexanediol and 1,4-cyclohexanediethanol. When the diol is preferably two of the above substances, the molar ratio of any two of the above diols is preferably 1:1.

[0041] In this invention, the molar ratio of the diol and dimethyl carbonate is preferably 0.75 to 0.8:1. The transesterification reaction is preferably carried out in a protective gas atmosphere, preferably an inert gas, such as argon or nitrogen in the embodiments. The transesterification reaction is preferably carried out under catalytic conditions, and the catalyst for the transesterification reaction is preferably a tetramethylethylenediamine stannous chloride complex. The mass percentage of the catalyst in the transesterification reaction relative to the total mass of the diol and dimethyl carbonate is preferably 0.01 to 0.02%.

[0042] In this invention, the transesterification reaction preferably includes: mixing a diol, dimethyl carbonate, and a catalyst in a protective gas atmosphere, then heating the mixture to 130–140°C for reflux reaction for 12–15 h, followed by heating to 170–180°C, controlling the reactor top temperature at 60–64°C during the heating process, and distilling to remove the byproduct (methanol), with the heating process preferably taking 10–12 h; after heating to 170–180°C until no byproduct is found, then evacuating to -0.1 MPa, with the evacuation time preferably taking 3–5 h; after evacuating to -0.1 MPa, cooling to 40–50°C to obtain liquid polycarbonate polyol.

[0043] In this invention, castor oil is preferably purchased from Huanyu Oils Co., Ltd.

[0044] In this invention, the additives preferably include one or more of a catalyst, a silane coupling agent, and a tackifying resin. The catalyst preferably includes one or more of bismuth octanoate, zinc neodecanoate, dimethylcyclohexylamine, triethylenediamine, stannous octanoate, dioctyltin dilaurate, and dibutyltin dilaurate, more preferably one or two of zinc neodecanoate, triethylenediamine, and dioctyltin dilaurate. The mass percentage of the catalyst relative to component A is preferably ≤0.5%, more preferably ≤0.05%, and even more preferably ≤0.02%. The addition of the catalyst can improve the curing speed of the polyurethane adhesive, enabling room temperature curing while maintaining the original high initial bond strength of the polyurethane adhesive, which is beneficial for the production of large-scale industrial products and improves production efficiency. In a specific embodiment of this invention, the catalyst is TMG216 (dioctyltin dilaurate) purchased from High Schmidt (Shanghai Manhai High Schmidt Chemical Co., Ltd.), which has high catalytic activity, low toxicity, low migration, and meets EU pollution testing standards.

[0045] In this invention, the silane coupling agent preferably comprises one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane. The mass percentage of the silane coupling agent relative to component A is preferably ≤4%, more preferably ≤2%. In this invention, the higher the mass percentage of the silane coupling agent relative to component A, the higher the modulus of the cured polyurethane adhesive, the better its hydrolysis resistance, and it can also synergistically improve the bonding strength with polycarbonate polyol and castor oil. In a specific embodiment of this invention, the silane coupling agent is CG-O187 (γ-glycidoxypropyltrimethoxysilane) purchased from Qufu Chenguang Chemical Co., Ltd.

[0046] In this invention, the tackifying resin is preferably an epoxy resin, more preferably a two-component type A epoxy resin and / or bisphenol F epoxy resin. Two-component type A epoxy resin has high polarity and excellent heat resistance, providing good rigidity and cohesive strength, and exhibits a significant synergistic toughening and reinforcing effect between epoxy and polyurethane. Bisphenol F epoxy resin, compared to bisphenol A epoxy resin, has lower viscosity, better toughness, high temperature resistance, and is environmentally friendly and safe, making it suitable for applications and fields with stricter environmental and safety requirements. The percentage of the tackifying resin by mass of component A is preferably ≤8%, more preferably ≤6%. The addition of the tackifier can improve the bonding strength of the polyurethane adhesive after curing, while also improving its resistance to damp heat. In a specific embodiment of this invention, the tackifying resin is E-51 purchased from Baling Petrochemical and / or EP862 epoxy resin from Henson Chemicals, USA.

[0047] In this invention, the organic solvent preferably includes one or more of ethyl acetate, butyl acetate, acetone, propylene glycol methyl ether acetate and dimethyl carbonate, more preferably one or two of ethyl acetate, butyl acetate and dimethyl carbonate, and even more preferably ethyl acetate and / or butyl acetate.

[0048] In this invention, the mass ratio of the polyester polyol to the polycarbonate polyol is (50-70):(5-15), preferably (55-65):(5-10), more preferably (6-12.5):1, and in the embodiments it can be 7.2:1, 12:1, 9:1 or 6:1.

[0049] In this invention, the mass ratio of the polyester polyol to castor oil is (50-70):(2-10), preferably (55-65):(2-8), more preferably (10-32):1, and in the examples it can be 18:1 or 20:1.

[0050] In this invention, the mass ratio of the polyester polyol to the auxiliaries is (50-70):(0-8), preferably (55-65):(0-6). In this invention, component A may or may not include auxiliaries. When component A includes auxiliaries, the mass ratio of the polyester polyol to the auxiliaries is more preferably (14-50):1.

[0051] In this invention, the mass ratio of the polyester polyol to the organic solvent is (50-70):(15-35), preferably (55-65):(20-30), more preferably (2-3):1, and in the embodiments it can be 2.25:1, 2.54:1, 2.4:1 or 2.2:1.

[0052] In this invention, the preferred mass ratio of the polyester polyol, polycarbonate polyol, castor oil, additives and organic solvent is (50-70):(5-15):(2-10):(0-8):(15-35), and more preferably (55-65):(5-10):(2-8):(0-6):(20-30).

[0053] In this invention, the preparation method of component A preferably includes the following steps: In a protective gas atmosphere, the polyester polyol, polycarbonate polyol, and castor oil are heated, then vacuumed and kept at that temperature. After a period of time, an auxiliary agent is added and the reaction continues. Finally, an organic solvent is added and mixed while the temperature is lowered to obtain component A. In this invention, the protective gas is preferably nitrogen. The heating temperature is preferably 110–130°C. The vacuum degree is preferably ≤-0.09 MPa, more preferably -0.09 to -0.1 MPa. The heat preservation temperature is preferably 110–130°C, preferably carried out under stirring conditions, and the heat preservation time is preferably 1–2 hours. After the heat preservation treatment, a composite polyol system is obtained. In this invention, the auxiliary agent is added to the composite polyol system and stirred during the reaction. The stirring reaction is carried out under vacuum conditions, preferably ≤-0.09 MPa, more preferably -0.09 to -0.1 MPa. The stirring reaction time is preferably 0.5–1 hour. The cooling process is preferably carried out to below 50°C. After adding the organic solvent, the present invention preferably continues to stir and mix to obtain component A.

[0054] In this invention, the water content of component A is preferably ≤300ppm.

[0055] The polyurethane adhesive provided by this invention includes an individually packaged component B. In this invention, component B is an isocyanate compound, and the isocyanate content of the isocyanate compound is 15-35%, preferably 18-33%. The test method for the isocyanate content of the isocyanate compound is titration according to the national standard GB / T 12009.4-2016.

[0056] In this invention, the isocyanate compound preferably includes one or more of polymethylene polyphenyl polyisocyanate (PAPI), carbodiimide-modified MDI, hexamethylene diisocyanate (HDI) trimer, and isophorone diisocyanate (IPDI) trimer; more preferably, it is a combination of polymethylene polyphenyl polyisocyanate (PAPI) and hexamethylene diisocyanate (HDI) trimer. In a specific embodiment of this invention, the isocyanate is M20S purchased from BASF and / or N3390 purchased from Covestro.

[0057] In this invention, the molar ratio of isocyanate group in component B to hydroxyl group in component A is preferably 1 to 1.5:1, more preferably 1.05 to 1.2:1, and in the examples it can be 1.1:1 or 1.2:1.

[0058] This invention provides a method for preparing the polyurethane adhesive described in the above technical solution, preferably comprising the following steps: mixing component A and component B to obtain the polyurethane adhesive. The viscosity of the polyurethane adhesive at 25°C is preferably 800–1500 mPa·s, more preferably 1000–1300 mPa·s.

[0059] This invention provides the application of the polyurethane adhesive described in the above technical solution in the composite of PET film and PET foam board.

[0060] In this invention, the application preferably includes the following steps:

[0061] The components A and B are mixed to obtain a colloid solution;

[0062] The adhesive is applied to the bonding surface of the PET foam board, and after solvent removal, it is laminated with the PET film material.

[0063] This invention involves mixing component A and component B to obtain a colloid. Preferably, the mixing is performed at room temperature. The mixing is carried out under stirring conditions. The viscosity of the colloid at 25°C is 800–1500 mPa·s, more preferably 1000–1300 mPa·s.

[0064] After obtaining the adhesive, the present invention coats the adhesive onto the bonding surface of the PET foam board, removes the solvent, and then laminates it with the PET film material.

[0065] In some embodiments of the present invention, prior to coating, the PET foam board and PET film can be pretreated, preferably by corona treatment. In embodiments of the present invention, the conditions for the corona treatment preferably include: a power of 1.5–2 A and a speed of 25–30 cm / min.

[0066] In some embodiments of the present invention, the thickness of the wet coating during coating can be 35 to 60 μm.

[0067] In this invention, the preferred method for solvent removal is drying. The preferred temperature for solvent removal is 90–120°C, and the preferred time is 2–6 minutes. This invention ensures complete evaporation of the solvent in the adhesive solution through solvent removal.

[0068] In this invention, the composite process preferably includes sequential pressing and curing. The curing temperature is preferably 20–60°C, and the curing time is preferably 24–72 hours.

[0069] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0070] The preparation method of the polycarbonate polyol used in the following examples is as follows:

[0071] A mixed diol (1,6-hexanediol and 1,4-cyclohexanediol, molar ratio 1:1), dimethyl carbonate, and a catalyst (tetramethylethylenediamine stannous chloride complex) were added to a dry reactor under an inert gas atmosphere (Ar). The molar ratio of the mixed polyol to dimethyl carbonate was 0.8:1, and the mass of the catalyst was 0.02% of the total feed mass (mixed diol and dimethyl carbonate).

[0072] The temperature was then raised to 130–140°C and refluxed for 12 hours. The temperature was then raised to 180°C, with the reactor top temperature controlled at 60–64°C during the heating process. The byproduct (methanol) was removed by distillation over 12 hours. After heating to 170–180°C until no byproduct remained, a vacuum was applied to -0.1 MPa for 5 hours. After further vacuuming to -0.1 MPa, the temperature was lowered to 50°C to obtain liquid polycarbonate polyol. The number-average molecular weight of the obtained liquid polycarbonate polyol was 900–1000, and the hydroxyl value was 115–135 mg KOH / g.

[0073] Example 1

[0074] Preparation of Component A: 1800g of polyester polyol (produced by Shanghai Shuyu Chemical Co., Ltd.) of brand name H3022, 250g of polycarbonate polyol (number average molecular weight 900-1000, hydroxyl value 115-135mg KOH / g) and 100g of castor oil were added to a reaction vessel. The mixture was heated to 120℃ under nitrogen protection, and then evacuated to -0.1MPa. After stirring for 2 hours, 800g of ethyl acetate and butyl acetate (mass ratio 7:3) were slowly added and the mixture was stirred and cooled to below 50℃. The mixture was stirred until the system was clear and transparent. After testing that the moisture content of the system was below 300ppm, the mixture was cooled to room temperature and filtered through a filter screen to obtain Component A.

[0075] Component A and component B (BASF's M20S) were mixed at a ratio of n(-NCO):n(-OH) = 1.1:1 and stirred until homogeneous to obtain a polyurethane adhesive for PET film-PET foam board composite. The adhesive was evenly applied to the bonding surface of the PET foam board and baked at 100°C for 5 minutes. Then, the PET film and PET foam board were pressed together and cured at 50°C for 24 hours to obtain the composite product, in accordance with GB / T The 2790-1995 standard tests its 180° peel strength. When PET is untreated, the test results are 11.5 N / cm after curing at 50℃ for 24 hours and 17.4 N / cm after boiling in water at 100℃ for 6 hours. When PET (PET foam board and PET film) is corona treated (corona treatment power is 1.5A, speed is 25cm / min), the test results are 16.3 N / cm after curing at 50℃ for 24 hours and 20.4 N / cm after boiling in water at 100℃ for 6 hours.

[0076] Example 2

[0077] Preparation of Component A: 1800g of polyester polyol (produced by Shanghai Shuyu Chemical Co., Ltd.) of brand name H3022, 150g of polycarbonate polyol (number average molecular weight 900-1000, hydroxyl value 115-135mg KOH / g) and 90g of castor oil were added to a reaction vessel. The mixture was heated to 120℃ under nitrogen protection, and then evacuated to -0.1MPa. The mixture was stirred for 2 hours. Then, 102g of EP862 epoxy resin was added and stirred under vacuum for 1 hour. 710g of ethyl acetate and butyl acetate (mass ratio 7:3) were slowly added and stirred until the temperature dropped to below 50℃. The mixture was stirred until the system was clear and transparent. The moisture content of the system was tested to be below 300ppm. The mixture was then cooled and filtered to obtain Component A.

[0078] Component A and component B (BASF's M20S or Covestro's N3390) were mixed at a ratio of n(-NCO):n(-OH) = 1.2:1 and stirred until homogeneous to obtain a polyurethane adhesive for PET film-PET foam board composite. The PET and foamed PET were subjected to corona treatment (power 1.5A, speed 25cm / min). The adhesive was then evenly applied to the bonding surface of the PET foam board and baked at 100℃ for 5 minutes. The PET film was then laminated with the PET foam board, and after curing at 50℃ for 24 hours, the composite product was obtained, conforming to GB / T According to the 2790-1995 standard, the 180° peel strength was tested. When component B was BASF's M20S, the peel strength was 21.5 N / cm after curing at 50°C for 24 hours and 26.3 N / cm after boiling in water at 100°C for 6 hours. When component B was Covestro's N3390, the peel strength was 12.9 N / cm after curing at 50°C for 24 hours and 17.9 N / cm after boiling in water at 100°C for 6 hours.

[0079] Example 3

[0080] Preparation of Component A: 1800g of polyester polyol (produced by Shanghai Shuyu Chemical Co., Ltd.) of brand H3022, 200g of polycarbonate polyol (number average molecular weight 900-1000, hydroxyl value 115-135mg KOH / g) and 100g of castor oil were added to a reaction vessel. The mixture was heated to 120℃ under nitrogen protection, and then evacuated to -0.1MPa. The mixture was stirred for 2 hours. Then, 37g of CG-O187 was added, and the mixture was stirred under vacuum for 1 hour. 750g of ethyl acetate and butyl acetate (mass ratio 7:3) were slowly added and the mixture was stirred and cooled to below 50℃. The mixture was stirred until the system was clear and transparent. After the moisture content of the system was tested to be below 300ppm, the mixture was cooled and filtered to obtain Component A.

[0081] Component A and component B (BASF's M20S or Covestro's N3390) were mixed at a ratio of n(-NCO):n(-OH) = 1.1:1 and stirred until homogeneous to obtain a polyurethane adhesive for PET film-PET foam board composite. The PET and foamed PET were subjected to corona treatment (power 1.5A, speed 25cm / min). The adhesive was then evenly applied to the bonding surface of the PET foam board and baked at 100℃ for 5 minutes. The PET film was then laminated with the PET foam board, and after curing at 50℃ for 24 hours, the composite product was obtained, conforming to GB / T According to the 2790-1995 standard, the 180° peel strength was tested. When component B was BASF's M20S, the peel strength was 21.4 N / cm after curing at 50°C for 24 hours and 25.8 N / cm after boiling in water at 100°C for 6 hours. When component B was Covestro's N3390, the peel strength was 12.3 N / cm after curing at 50°C for 24 hours and 17.1 N / cm after boiling in water at 100°C for 6 hours.

[0082] Example 4

[0083] Preparation of Component A: 1800g of polyester polyol (produced by Shanghai Shuyu Chemical Co., Ltd.) of brand name H3022, 150g of polycarbonate polyol (number average molecular weight 900-1000, hydroxyl value 115-135mg KOH / g) and 90g of castor oil were added to a reaction vessel. The mixture was heated to 120℃ under nitrogen protection, and then evacuated to -0.1MPa. The mixture was stirred for 2 hours. Then, 102g of EP862 epoxy resin and 0.28g of TMG216 were added. The mixture was stirred under vacuum for 1 hour. 710g of ethyl acetate was slowly added and stirred until the temperature dropped to below 50℃. The mixture was stirred until the system was clear and transparent. The moisture content of the system was tested to be below 300ppm. The mixture was then cooled and filtered to obtain Component A.

[0084] Component A and component B (BASF's M20S) were mixed at a ratio of n(-NCO):n(-OH) = 1.2:1 and stirred until homogeneous to obtain a polyurethane adhesive for PET film-PET foam board composite. PET and foamed PET were subjected to corona treatment (power of 1.5A, speed of 25cm / min). The adhesive was then evenly applied to the bonding surface of the PET foam board and baked at 90℃ for 3 minutes. The PET film was then laminated with the PET foam board and cured at 25℃ for 48 hours to obtain the composite product. Its 180° peel strength was tested according to GB / T 2790-1995 standard. The test results showed that the peel strength after curing at 25℃ for 48 hours was 20.4 N / cm, and the peel strength after boiling in water at 100℃ for 6 hours was 25.9 N / cm.

[0085] Example 5

[0086] Preparation of Component A: 1800g of polyester polyol (produced by Shanghai Shuyu Chemical Co., Ltd.) of brand name H3020, 250g of polycarbonate polyol (number average molecular weight 900-1000, hydroxyl value 115-135mg KOH / g) and 90g of castor oil were added to a reaction vessel. The mixture was heated to 120℃ under nitrogen protection, and then evacuated to -0.1MPa. The mixture was stirred for 2 hours. Then, 128g of E-51 epoxy resin and 0.31g of TMG216 were added. The mixture was stirred under vacuum for 1 hour. 800g of ethyl acetate was slowly added and stirred until the temperature dropped to below 50℃. The mixture was stirred until the system was clear and transparent. The moisture content of the system was tested to be below 300ppm. The mixture was then cooled and filtered to obtain Component A.

[0087] Component A and component B (BASF's M20S) were mixed at a ratio of n(-NCO):n(-OH) = 1.2:1 and stirred until homogeneous to obtain a polyurethane adhesive for PET film / PET foam board composite. PET and foamed PET were subjected to corona treatment (corona treatment power of 1.5A, speed of 25cm / min). The adhesive was then evenly applied to the bonding surface of the PET foam board and baked at 90℃ for 3min. The PET film was then laminated with the PET foam board, and after curing at 25℃ for 48h, the composite product was obtained. Its 180° peel strength was tested according to GB / T 2790-1995 standard. The test results showed that the peel strength after curing at 25℃ for 48h was 19.6N / cm, and the peel strength after boiling in water at 100℃ for 6h was 24.6N / cm.

[0088] Example 6

[0089] Preparation of Component A: 1800g of polyester polyol (produced by Shanghai Shuyu Chemical Co., Ltd.) of brand name H3022, 200g of polycarbonate polyol (number average molecular weight 900-1000, hydroxyl value 115-135mg KOH / g) and 100g of castor oil were added to a reaction vessel. The mixture was heated to 120℃ under nitrogen protection, and then evacuated to -0.1MPa. The mixture was stirred for 2 hours. Then, 37g of CG-O187 and 0.29g of TMG216 were added, and the mixture was stirred under vacuum for 1 hour. 750g of ethyl acetate was slowly added and the mixture was stirred and cooled to below 50℃. The mixture was stirred until the system was clear and transparent. The moisture content of the system was tested to be below 300ppm. The mixture was then cooled and filtered to obtain Component A.

[0090] Component A and component B (BASF's M20S) were mixed at a ratio of n(-NCO):n(-OH) = 1.1:1 and stirred until homogeneous to obtain a polyurethane adhesive for PET film-PET foam board composite. PET and foamed PET were subjected to corona treatment (corona treatment power of 1.5A, speed of 25cm / min). The adhesive was then evenly applied to the bonding surface of the PET foam board and baked at 90℃ for 3min. The PET film was then laminated with the PET foam board and cured at 25℃ for 48h to obtain the composite product. Its 180° peel strength was tested according to GB / T 2790-1995 standard. The test results showed that the peel strength after curing at 25℃ for 48h was 20.3N / cm, and the peel strength after boiling in water at 100℃ for 6h was 24.8N / cm.

[0091] Example 7

[0092] Preparation of Component A: 1800g of polyester polyol (produced by Shanghai Shuyu Chemical Co., Ltd.) of brand name H3020, 300g of polycarbonate polyol (number average molecular weight 900-1000, hydroxyl value 115-135mg KOH / g) and 100g of castor oil were added to a reaction vessel. The mixture was heated to 120℃ under nitrogen protection, and then evacuated to -0.1MPa. The mixture was stirred for 2 hours. Then, 44g of CG-O187 and 0.30g of TMG216 were added, and the mixture was stirred under vacuum for 1 hour. 820g of ethyl acetate was slowly added and the mixture was stirred and cooled to below 50℃. The mixture was stirred until the system was clear and transparent. The moisture content of the system was tested to be below 300ppm. The mixture was then cooled and filtered to obtain Component A.

[0093] Component A and component B (BASF's M20S) were mixed at a ratio of n(-NCO):n(-OH) = 1.1:1 and stirred until homogeneous to obtain a polyurethane adhesive for PET film / PET foam board composite. PET and foamed PET were subjected to corona treatment (corona treatment power of 1.5A, speed of 25cm / min). The adhesive was then evenly applied to the bonding surface of the PET foam board and baked at 90℃ for 3min. The PET film was then laminated with the PET foam board and cured at 25℃ for 48h to obtain the composite product. Its 180° peel strength was tested according to GB / T 2790-1995 standard. The test results showed that the peel strength after curing at 25℃ for 48h was 19.1N / cm, and the peel strength after boiling in water at 100℃ for 6h was 23.9N / cm.

[0094] The pot life of the polyurethane adhesive for PET film / PET foam board composite prepared in Examples 1-7 was tested. The test method was as follows: the A and B components of the polyurethane adhesive for PET film / PET foam board composite were thoroughly mixed at 25°C, and the viscosity was tested. The results showed that the polyurethane adhesive prepared in Examples 1-7 of the present invention had a viscosity of less than 1500 mPa·s after mixing at 25°C for 3-5 minutes, less than 2100 mPa·s after mixing for 2 hours, and still less than 2800 mPa·s after 3 hours. It can be seen that the polyurethane adhesive for PET film / PET foam board composite provided by the present invention has a long pot life.

[0095] Comparative Example 1

[0096] The D5910A main agent for bonding PET materials, purchased from Wuhan Daerhui Technology Co., Ltd., and BASF's M20S or Covestro's N3390 were mixed at a ratio of n(-NCO):n(-OH) = 1.1:1. The mixture was stirred until homogeneous to obtain a polyurethane adhesive for PET film / PET foam board composite. The adhesive was evenly applied to the bonding surface of the PET foam board and baked at 90℃ for 5 minutes. Then, the PET film and PET foam board were laminated together, and after curing at 50℃ for 48 hours, the composite material was obtained. For the composite product, the 180° peel strength was tested according to GB / T2790-1995 standard. When the PET was untreated and component B was BASF's M20S, the peel strength was 7.2 N / cm after curing at 50℃ for 48 hours and 8.4 N / cm after boiling in water at 100℃ for 6 hours. When component B was Covestro's N3390, the peel strength was 6.1 N / cm after curing at 50℃ for 48 hours and 7.8 N / cm after boiling in water at 100℃ for 6 hours. When PET is corona treated, the peel strength of component B is BASF's M20S after curing at 50℃ for 48 hours and the peel strength of component B after boiling in water at 100℃ for 6 hours is 10.2 N / cm. When component B is Covestro's N3390, the peel strength of component B is 10.0 N / cm after curing at 50℃ for 48 hours and the peel strength of component B after boiling in water at 100℃ for 6 hours is 12.1 N / cm.

[0097] Compared to the present invention, D5910A polyurethane adhesive requires 48 hours of curing at 50°C to achieve complete curing. The long curing time and high temperature are not conducive to situations where construction efficiency is required or where large-sized structural components are being bonded. The bonding strength is also lower than that of the present invention, and it cannot meet the bonding strength requirements of certain situations, such as structural components.

[0098] As can be seen from the above embodiments, the polyurethane adhesive provided by the present invention has good flexibility, can be perfectly adapted to PET film and foam board, and has excellent wetting properties on PET substrate; even untreated PET bonding can achieve high peel strength, and the bonding strength is even higher after boiling in water at 100℃; after corona treatment, the adhesive can form a multiple hydrogen bond network on the PET surface, further improving the bonding strength of PET film / PET foam board; the curing speed is controllable, and it can be cured at high temperature for rapid curing or at room temperature to match the construction process of large-size structural parts, with a long service life, simple operation process, and convenient construction. At the same time, the present invention uses bio-based raw materials, low-toxicity catalysts, and low-VOC solvents, which have environmental protection and safety advantages, and can be used in a variety of occasions and fields such as construction and home decoration. For example, it can be used in PET composite boards exported to the EU to replace PVC composite boards that may be restricted in the future due to safety issues.

[0099] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A polyurethane adhesive, characterized in that, Includes individually packaged components A and B; Component A comprises polyester polyol, polycarbonate polyol, castor oil, additives, and organic solvents. The number average molecular weight of the polyester polyol is ≥4500. The mass ratio of the polyester polyol to the polycarbonate polyol is (50-70):(5-15), the mass ratio of the polyester polyol to the castor oil is (50-70):(2-10), the mass ratio of the polyester polyol to the additives is (50-70):(0-8), and the mass ratio of the polyester polyol to the organic solvent is (50-70):(15-35). Component B is an isocyanate compound, and the isocyanate content of the isocyanate compound is 15-35%.

2. The polyurethane adhesive according to claim 1, characterized in that, The molar ratio of isocyanate group in component B to hydroxyl group in component A is 1 to 1.5:

1.

3. The polyurethane adhesive according to claim 1, characterized in that, The number-average molecular weight of the polyester polyol is 4500-8500, and the hydroxyl value is 10-35 mg KOH / g; The polycarbonate polyol has a number-average molecular weight of 500–4000 and a hydroxyl value of 28–250 mg KOH / g; The additives include one or more of catalysts, silane coupling agents, and tackifying resins; The organic solvent includes one or more of ethyl acetate, butyl acetate, acetone, propylene glycol methyl ether acetate, and dimethyl carbonate.

4. The polyurethane adhesive according to claim 1 or 3, characterized in that, The method for preparing the polycarbonate polyol includes: subjecting a diol and dimethyl carbonate to an ester exchange reaction to obtain the polycarbonate polyol; The diol includes at least two of 1,6-hexanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,4-pentanediol, and 1,4-cyclohexanediol.

5. The polyurethane adhesive according to claim 3, characterized in that, The catalyst comprises one or more of bismuth octanoate, zinc neodecanoate, dimethylcyclohexylamine, triethylenediamine, stannous octanoate, dioctyltin dilaurate, and dibutyltin dilaurate, wherein the mass percentage of the catalyst relative to the mass of component A is ≤0.5%. The silane coupling agent includes one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and the mass percentage of the silane coupling agent to the mass of component A is ≤4%. The tackifying resin is an epoxy resin, and the mass percentage of the tackifying resin in component A is ≤8%.

6. The polyurethane adhesive according to claim 1 or 2, characterized in that, The preparation method of component A includes the following steps: In a protective gas atmosphere, the polyester polyol, polycarbonate polyol and castor oil are heated, then vacuumed and kept at that temperature. After a period of time, additives are added and the reaction continues. Finally, an organic solvent is added and mixed while the mixture is cooled to obtain component A. The water content of component A is ≤300ppm.

7. The polyurethane adhesive according to claim 1 or 2, characterized in that, The isocyanate compounds include one or more of polymethylene polyphenyl polyisocyanate, carbodiimide-modified MDI, hexamethylene diisocyanate trimer, and isophorone diisocyanate trimer.

8. The application of the polyurethane adhesive according to any one of claims 1 to 7 in the composite of PET film and PET foam board.

9. The application according to claim 8, characterized in that, The application includes the following steps: The components A and B are mixed to obtain a colloid solution; The adhesive is applied to the bonding surface of the PET foam board, and after solvent removal, it is laminated with the PET film material.

10. The application according to claim 9, characterized in that, The viscosity of the adhesive solution at 25°C is 800–1500 mPa·s; The solvent removal temperature is 90–120°C, and the time is 2–6 min; The compounding process includes sequential pressing and curing, wherein the curing temperature is 20–60°C and the time is 24–72 h.