Two-component transparent polyurethane pouring sealant and preparation method thereof

Abstract

The invention relates to a two-component transparent polyurethane pouring sealant and a preparation method thereof, and belongs to the technical field of pouring sealants. The bi-component transparent polyurethane pouring sealant comprises a component A and a component B, wherein the component A comprises an isocyanate-terminated polyurethane prepolymer; the isocyanate-terminated polyurethane prepolymer is generated by reaction of an aromatic diisocyanate monomer and castor oil-based phthalic anhydride polyester polyol; the component B comprises a polyhydroxy curing agent and an organic metal catalyst; the polyhydroxy curing agent is castor oil and / or castor oil-based phthalic anhydride polyester polyol. The insulation performance of a test piece encapsulated by the bi-component transparent polyurethane pouring sealant is tested under the high-temperature and high-humidity conditions that the temperature is 85 DEG C and the relative humidity is 85%, the insulation level can be reached and can be maintained for more than 7 days, the volume resistivity at 90 DEG C is not greatly reduced compared with the volume resistivity at 23 DEG C, and the test piece shows good electrical property and long service life.

Description

Technical Field

[0001] The invention relates to a two-component transparent polyurethane potting adhesive and a preparation method thereof, belonging to the technical field of potting adhesives. Background Art

[0002] Polyurethane potting glue, also known as PU potting glue, is a commonly used electronic potting glue. Polyurethane is gradually polymerized from oligomer polyols such as polyester, polyether and polydiolefin, small molecule diols or diamine chain extenders and diisocyanates. It has excellent mechanical properties and performance. Usually, polyurethane potting glue is a two-component product. When used, the two components are mixed in a certain proportion for potting operation. For example, in the prior art, the Chinese invention patent with the authorization announcement number CN105885767B discloses an MDI-based polyurethane electronic potting glue, which is composed of two components A and B; wherein the component A is made of 50-60 parts by weight of isocyanate, 15-20 parts of oligomer polyol and 9-30 parts of reactive liquid flame retardant, wherein the isocyanate is one of MDI, carbodiimide-modified MDI, PAPI or a mixture of any of the above; the component B is made of 55-100 parts by weight of oligomer polyol, 1.0-3.5 parts of cross-linking chain extender, 0.01-0.1 parts of catalyst, 105-140 parts of filler, 0.5-1 parts of defoamer and 0.5-1 parts of antioxidant. The polyurethane has good adhesion, water resistance, flame retardancy, thermal conductivity and electrical properties. However, due to the complex working environment of electronic products, once the external environment such as temperature changes, the potting compound as the insulating protective layer will be affected first. The insulation properties of existing polyurethane potting compounds usually change greatly when the temperature changes, which can easily cause the insulation layer to fail, and the circuits to have leakage, short circuits and other problems, thus causing electronic products to malfunction. Summary of the invention

[0003] The invention aims to provide a two-component transparent polyurethane potting adhesive whose volume resistivity is less affected by temperature.

[0004] The present invention also aims to provide a method for preparing the above two-component transparent polyurethane potting glue.

[0005] In order to achieve the above purpose, the technical solution adopted by the two-component transparent polyurethane potting glue of the present invention is:

[0006] A two-component transparent polyurethane potting adhesive comprises component A and component B; component A comprises an isocyanate-terminated polyurethane prepolymer; the isocyanate-terminated polyurethane prepolymer is produced by the reaction of an aromatic diisocyanate monomer and a castor oil-based phthalic anhydride polyester polyol; component B comprises a polyhydroxy curing agent and an organic metal catalyst; the polyhydroxy curing agent is castor oil and / or castor oil-based phthalic anhydride polyester polyol.

[0007] The two-component transparent polyurethane potting glue of the present invention, the castor oil-based phthalic anhydride polyester polyol synthesized in component A of the terminal isocyanate-based polyurethane prepolymer is a castor oil-based polyester polyol with a suitable crosslinking degree and reactivity, which can provide more benzene ring skeletons while avoiding the generation of gel in the synthesis process, and can improve the heat resistance of the product, reduce the influence of temperature on the insulation performance, so that the volume resistivity at 90°C does not drop significantly compared with 23°C, showing good electrical properties. The test piece potted by the two-component transparent polyurethane potting glue of the present invention has a long service life even under harsh conditions of high temperature and high humidity.

[0008] Furthermore, the polyhydroxy curing agent in the component B is castor oil and / or castor oil-based phthalic anhydride polyester polyol. Castor oil and castor oil-based phthalic anhydride polyester polyol can provide better electrical properties when combined with component A based on their own characteristics.

[0009] Furthermore, the mass percentage of isocyanate groups in component A is 12-18%. In order to make the two-component potting adhesive have suitable viscosity and comprehensive performance, the viscosity of component A at 23°C is not higher than 400cp, and the viscosity of component B at 23°C is not higher than 500cp.

[0010] Furthermore, the component A also includes epoxy resin; the epoxy group in the epoxy resin can react with the carboxyl group generated by the hydrolysis of the polyurethane, thereby inhibiting the catalytic effect of the carboxyl group on the hydrolysis and improving the high temperature and high humidity resistance of the product.

[0011] Preferably, the mass ratio of the epoxy resin to the castor oil-based phthalic anhydride polyester polyol used to produce the isocyanate-terminated polyurethane prepolymer is 3-5:15-30, for example, 3:15-30.

[0012] Preferably, the epoxy resin is a liquid epoxy resin. The liquid epoxy resin of the present invention refers to an epoxy resin with a viscosity of ≤25000cp at 25°C. The use of liquid epoxy resin can make component A have a lower viscosity, and the two-component transparent polyurethane potting glue is easier to mix when used, and it is conducive to the discharge of bubbles. The epoxy resin is preferably a bisphenol A type epoxy resin and / or a bisphenol F type epoxy resin. Furthermore, the mass ratio of the castor oil-based phthalic anhydride polyester polyol and the aromatic diisocyanate monomer used to generate the terminal isocyanate polyurethane prepolymer is 150-300:410-600, for example, 150-300:450-600. The castor oil-based phthalic anhydride polyester polyol used to generate the terminal isocyanate polyurethane prepolymer has a hydroxyl value of 160-230 mgKOH / g and an average functionality of 2.0-2.5.

[0013] Further, the isocyanate-terminated polyurethane prepolymer is formed by reacting castor oil-based phthalic anhydride polyester polyol and aromatic diisocyanate monomer at 65-70° C. for 2-3 hours under vacuum conditions, and then adding a catalyst to continue reacting at 65-70° C. for 1-1.5 hours under vacuum conditions. For example, the isocyanate-terminated polyurethane prepolymer is formed by reacting castor oil-based phthalic anhydride polyester polyol and aromatic diisocyanate monomer at 67-68° C. for 3 hours under vacuum conditions, and then adding a catalyst to continue reacting at 67-68° C. for 1 hour under vacuum conditions. The catalyst is preferably bismuth carboxylate.

[0014] Furthermore, the component A also includes an adhesion promoter. In component A, the mass ratio of the adhesion promoter to the castor oil-based phthalic anhydride polyester polyol used to generate the terminal isocyanate-based polyurethane prepolymer is 1.5-3.5:15-30, for example, 2:15-30. In component A, the adhesion promoter is preferably a vinyl silane adhesion promoter, for example, vinyl triethoxy silane. Vinyl silane contains unsaturated double bonds. Component A uses vinyl silane as an adhesion promoter to improve adhesion to plastic substrates. At the same time, vinyl silane is very easy to hydrolyze, and the water content of component A can also be reduced, thereby improving its storage performance and reducing the generation of bubbles during the curing process.

[0015] Furthermore, the component A also includes additives; the additives include plasticizers, flame retardants and antioxidants. In component A, the mass ratio of the plasticizer to the castor oil-based phthalic anhydride polyester polyol used to generate the terminal isocyanate polyurethane prepolymer is 1:0.75-3.3, for example, 1:0.98-3.27; the mass ratio of the flame retardant to the plasticizer is 1:1-4, for example, 1:1.15-1.9125; the mass of the antioxidant is 0.5%-1% of the total mass of component A and component B.

[0016] Furthermore, the component B also includes a substrate wetting agent. Adding the substrate wetting agent to the component B can reduce the surface tension of the potting glue, improve the wetting performance to the substrate, thereby improving the adhesion to the substrate, and at the same time reduce the bubbles generated during the flow process. The substrate wetting agent is one or two of an organic silicon nonionic surfactant and a fluorine-containing surfactant. The mass of the substrate wetting agent is 0.1% to 0.5% of the total mass of the components A and B.

[0017] Furthermore, the component B also includes an adhesion promoter. In component B, the mass ratio of the adhesion promoter to the polyol curing agent is 1:59 to 91.2. In component B, the adhesion promoter is a silane coupling agent; the silane coupling agent is one or any combination of silane coupling agent KH-560, silane coupling agent A-189, and silane coupling agent A-1170. Further, in component B, the mass ratio of the organic metal catalyst to the polyol curing agent is 0.01 to 6:700 to 935, for example, 0.3:700 to 912. The organic metal catalyst is preferably an organic tin catalyst, for example, dibutyltin dilaurate.

[0018] Furthermore, the component B also includes additives; the additives include plasticizers and defoamers; the mass ratio of the plasticizer, defoamer and polyhydroxy curing agent in component B is 30-277:7-8:700-912.

[0019] Furthermore, the component B also includes a co-catalyst; the co-catalyst is polyamide. The role of the co-catalyst is to increase the pH value of the system and increase the post-curing speed. The mass ratio of the co-catalyst to the polyhydroxy curing agent is preferably 0.014-7:700-1200, for example, 0.2:700-912.

[0020] Furthermore, when the polyhydroxy curing agent comprises castor oil-based phthalic anhydride polyester polyol, the hydroxyl value of the castor oil-based phthalic anhydride polyester polyol contained in the polyhydroxy curing agent is preferably 160 to 230 mgKOH / g. The present invention does not need to limit the functionality of the castor oil-based polyester polyol in the polyhydroxy curing agent, and existing products can be used, for example, castor oil-based polyester polyol products with an average functionality of 2.5 to 3.0 can be selected. The acid value of the castor oil-based phthalic anhydride polyester polyol is ≤2 mgKOH / g.

[0021] Furthermore, the aromatic diisocyanate monomer is diphenylmethane diisocyanate and / or toluene diisocyanate. Pure MDI, MDI-50, etc. can be used as raw materials for providing diphenylmethane diisocyanate.

[0022] Further, the plasticizer is one or any combination of alkyl phenyl sulfonate, phthalic acid plasticizer, and terephthalic acid ester plasticizer. The phthalic acid ester plasticizer is one or any combination of dioctyl phthalate (DOP), diisooctyl phthalate, diisodecyl phthalate, and diisononyl phthalate. The terephthalic acid plasticizer is preferably dioctyl terephthalate (DOTP).

[0023] Furthermore, the flame retardant is a phosphate flame retardant. The phosphate flame retardant is one or any combination of dimethyl methylphosphonate (DMMP), diethyl ethylphosphonate (DEEP), triethyl phosphate (TEP), 3,4-dimethyl-pyrazole phosphate (DMPP), triphenyl phosphate (TPP), and tricresyl phosphate (TCP).

[0024] Furthermore, the antioxidant is one or any combination of antioxidant 245, antioxidant 1010, antioxidant 1035, and antioxidant 1076.

[0025] The two-component transparent polyurethane potting glue of the present invention is a transparent elastic potting glue with excellent water resistance and high and low temperature resistance. It can make the potting test piece maintain good electrical insulation (resistance 4*10 12 Ω or more), showing a good service life.

[0026] When the two-component transparent polyurethane potting adhesive of the present invention is used, component A and component B are mixed in a certain ratio, for example, component A and component B are mixed in a ratio of 1:0.9 to 1.1. Furthermore, in the two-component transparent polyurethane potting adhesive, the mass ratio of component A to component B is 1:1.

[0027] The technical solution adopted by the preparation method of the two-component transparent polyurethane potting glue of the present invention is:

[0028] A preparation method of the above-mentioned two-component transparent polyurethane potting glue comprises the following steps: dehydrating a material whose main component is castor oil-based phthalic anhydride polyester polyol, reacting the material with an aromatic diisocyanate monomer at 65-70°C under vacuum conditions for 2-3 hours, adding a catalyst, and continuing to react at 65-70°C under vacuum conditions for 1-1.5 hours, adding an adhesion promoter after cooling, and mixing to obtain component A; dehydrating a material whose main component is a polyhydroxy curing agent, adding an additional material and mixing to obtain component B; the additional material comprises an organic metal catalyst.

[0029] The preparation method of the two-component transparent polyurethane potting glue of the present invention has a simple process. The test piece potted with the prepared two-component transparent polyurethane potting glue is placed under high temperature and high humidity conditions of 85°C and 85% for one week. In this state, the resistance of the test piece can still reach the insulation level (4*10 12 Ω), and the volume resistivity at 90°C did not decrease significantly compared to that at 23°C.

[0030] Furthermore, the dehydration temperature is 100-120° C. The dehydration time is 1-2 hours. The dehydration treatment is carried out under vacuum conditions. The system is stirred during the dehydration treatment. The reaction before and after the addition of the catalyst is carried out under stirring.

[0031] Furthermore, when preparing component A, the temperature is lowered to below 60° C. before adding the adhesion promoter.

[0032] Furthermore, when component A includes epoxy resin, the material whose main component is castor oil-based phthalic anhydride polyester polyol also includes epoxy resin.

[0033] Furthermore, when component A includes additives, the material whose main component is castor oil-based phthalic anhydride polyester polyol also includes additives; the additives include plasticizers, flame retardants and antioxidants.

[0034] Furthermore, when component B includes a plasticizer, the material whose main component is a polyhydroxy curing agent also includes a plasticizer.

[0035] Furthermore, when component B includes an adhesion promoter, the additive material also includes an adhesion promoter.

[0036] Furthermore, when component B includes a defoaming agent, the added material also includes a defoaming agent.

[0037] Furthermore, when component B includes a promoter, the added material also includes a promoter. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0039] The castor oil-based phthalic anhydride polyester polyols used in the following examples and comparative examples are all commercially available products.

[0040] Example 1

[0041] The two-component transparent polyurethane potting adhesive of this embodiment includes component A and component B, and the mass ratio of component A to component B is 1:1; component A mainly consists of terminal isocyanate isocyanate prepolymer, dioctyl terephthalate (DOTP), flame retardant TCP, bisphenol A type epoxy resin E51, antioxidant 1010, vinyl triethoxy silane and bis(carboxylate); component A is prepared by a method comprising the following steps:

[0042] In a three-necked flask, 300 g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 160 mgKOH / g and an average functionality of 2.5, 92 g of DOTP, 80 g of flame retardant TCP, 30 g of bisphenol A epoxy resin E51, and 10 g of antioxidant 1010 were added, heated to 120°C, and dehydrated by stirring under vacuum for 2 hours, then cooled to 65°C, 458 g of pure MDI was added, and after stirring and reacting at 67°C under vacuum for 3 hours, about 0.05 g of bismuth carboxylate was added, and the reaction was continued at 67°C under vacuum with stirring for 1 hour, and then the temperature was lowered to 60°C, the vacuum was released by nitrogen, 20 g of vinyl triethoxy silane was added, and stirring was continued for 10 minutes; the NCO% value of the test component A was 12%.

[0043] Component B consists of castor oil-based phthalic anhydride polyester polyol, dioctyl terephthalate (DOTP), silane coupling agent KH-560, fluorine-containing surfactant, defoamer, dibutyltin dilaurate and polyamide; component B is prepared by a method comprising the following steps:

[0044] Take 700g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 230mgKOH / g and an average functionality of 3, and 277g of DOTP, heat and vacuum dehydrate for 2h, then cool to room temperature, then add 10g of silane coupling agent KH-560, 8g of defoaming agent, 3g of fluorinated surfactant, 0.3g of dibutyltin dilaurate, and 0.2g of polyamide, mix well and disperse evenly.

[0045] Example 2

[0046] The two-component transparent polyurethane potting adhesive of this embodiment includes component A and component B, and the mass ratio of component A to component B is 1:1; component A mainly consists of terminal isocyanate isocyanate prepolymer, dioctyl phthalate (DOP), flame retardant TCP, NPEF-170 bisphenol F type epoxy resin, antioxidant 1076, vinyl triethoxy silane and bis(carboxylate); component A is prepared by a method comprising the following steps:

[0047] Add 270g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 180mgKOH / g and an average functionality of 2.5, 122g of DOP, 80g of flame retardant TCP, 30g of NPEF-170 bisphenol F epoxy resin, and 10g of antioxidant 1076 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 460g of MDI-50, stir and react at 68°C under vacuum for 3h, then add about 0.05g of bismuth carboxylate, continue to stir and react at 68°C under vacuum for 1h, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 12%.

[0048] Component B consists of castor oil, dioctyl phthalate (DOP), silane coupling agent KH-560, defoamer, organosilicon nonionic surfactant, dibutyltin dilaurate and polyamide; component B is prepared by a method comprising the following steps:

[0049] Take 900g of castor oil with a hydroxyl value of 165mgKOH / g and an average functionality of 2.7, and 78g of DOP, heat and vacuum dehydrate for 2h, then cool to room temperature, then add 10g of silane coupling agent KH-560, 7g of defoamer, 3g of polyether modified silicone oil, 0.3g of dibutyltin dilaurate, and 0.2g of polyamide, mix well and disperse evenly.

[0050] Example 3

[0051] The two-component transparent polyurethane potting adhesive of this embodiment includes component A and component B, and the mass ratio of component A to component B is 1:1; component A mainly consists of terminal isocyanate isocyanate prepolymer, dioctyl phthalate (DOP), flame retardant TCP, bisphenol A type epoxy resin E51, antioxidant 1010, vinyl triethoxy silane and bis(carboxylate); component A is prepared by a method comprising the following steps:

[0052] Add 200g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 180mgKOH / g and an average functionality of 2.5, 133g of DOP, 80g of flame retardant TCP, 30g of bisphenol A epoxy resin E51, and 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 527g of MDI-50, stir and react at 68°C under vacuum for 3h, then add about 0.05g of bis(triethoxy)carboxylate, continue to stir and react at 68°C under vacuum for 1h, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 15%.

[0053] Component B is composed of castor oil-based phthalic anhydride polyester polyol, dioctyl terephthalate (DOTP), silane coupling agent A-1170, defoamer, fluorinated surfactant, dibutyltin dilaurate and polyamide. Component B is prepared by a method comprising the following steps:

[0054] Take 851g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 220mgKOH / g and an average functionality of 2.7, and 130g of DOTP, heat and vacuum dehydrate for 2h, then cool to room temperature, then add 10g of silane coupling agent A-1170, 7g of defoaming agent, 3g of fluorinated surfactant, 0.3g of dibutyltin dilaurate, and 0.2g of polyamide, mix well and disperse evenly.

[0055] Example 4

[0056] The two-component transparent polyurethane potting adhesive of this embodiment includes component A and component B, and the mass ratio of component A to component B is 1:1; component A mainly consists of terminal isocyanate isocyanate prepolymer, dioctyl phthalate (DOP), flame retardant TCP, NPEF-170 bisphenol F type epoxy resin, antioxidant 1010, vinyl triethoxy silane and bis(carboxylate); component A is prepared by a method comprising the following steps:

[0057] Add 150g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 230mgKOH / g and an average functionality of 2, 153g of (DOP), 80g of flame retardant TCP, 30g of NPEF-170 bisphenol F epoxy resin, and 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 553g of MDI-50, stir and react at 68°C under vacuum for 3h, then add about 0.05g of bis(triethoxy)carboxylate, continue to stir and react at 68°C under vacuum for 1h, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 16%.

[0058] Component B consists of castor oil-based phthalic anhydride polyester polyol, dioctyl phthalate (DOP), silane coupling agent KH-560, defoamer, fluorinated surfactant, dibutyltin dilaurate and polyamide; component B is prepared by a method comprising the following steps:

[0059] Take 890g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 210mgKOH / g and an average functionality of 2.5, and 90g of DOP. Heat and vacuum dehydrate for 2h, then cool to room temperature, then add 15g of silane coupling agent KH-560, 7g of defoaming agent, 3g of fluorinated surfactant, 0.3g of dibutyltin dilaurate, and 0.2g of polyamide, mix well and disperse evenly.

[0060] Example 5

[0061] The two-component transparent polyurethane potting adhesive of this embodiment includes component A and component B, and the mass ratio of component A to component B is 1:1; component A mainly consists of terminal isocyanate isocyanate prepolymer, dioctyl terephthalate (DOTP), flame retardant TCP, bisphenol A type epoxy resin E51, antioxidant 1010, vinyl triethoxy silane and bis(carboxylate); component A is prepared by a method comprising the following steps:

[0062] Add 170g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 180mgKOH / g and an average functionality of 2.5, 96g of DOTP, 80g of flame retardant TCP, 30g of epoxy resin E51, and 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 594g of MDI-50, stir and react at 68°C under vacuum for 3h, then add about 0.05g of bismuth carboxylate, continue to stir and react at 68°C under vacuum for 1h, then cool to 60°C, release the vacuum by nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 18%.

[0063] Component B consists of castor oil-based phthalic anhydride polyester polyol, dioctyl terephthalate (DOTP), silane coupling agent A-1170, defoamer, organosilicon nonionic surfactant, dibutyltin dilaurate and polyamide; component B is prepared by a method comprising the following steps:

[0064] Take 912g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 230mgKOH / g and an average functionality of 3, and 68g of DOTP, heat and vacuum dehydrate for 2h, then cool to room temperature, then add 10g of silane coupling agent A-1170, 7g of defoaming agent, 3g of polyether modified silicone oil, 0.3g of dibutyltin dilaurate, and 0.2g of polyamide, mix well and disperse evenly.

[0065] Example 6

[0066] The two-component transparent polyurethane potting adhesive of this embodiment includes component A and component B, and the mass ratio of component A to component B is 1:1; component A mainly consists of terminal isocyanate isocyanate prepolymer, dioctyl phthalate (DOP), flame retardant TCP, bisphenol A type epoxy resin E51, antioxidant 1010, vinyl triethoxy silane and bis(carboxylate); component A is prepared by a method comprising the following steps:

[0067] Add 200g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 180mgKOH / g and an average functionality of 2.5, 133g of DOP, 80g of flame retardant TCP, 30g of bisphenol A epoxy resin E51, and 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 527g of MDI-50, stir and react at 68°C under vacuum for 3h, then add about 0.05g of bis(triethoxy)carboxylate, continue to stir and react at 68°C under vacuum for 1h, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 15%.

[0068] Component B consists of castor oil-based phthalic anhydride polyester polyol, dioctyl terephthalate (DOTP), silane coupling agent A-1170, defoamer, dibutyltin dilaurate and polyamide; component B is prepared by a method comprising the following steps:

[0069] Take 851g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 220mgKOH / g and an average functionality of 2.7, and 130g of DOTP, heat and vacuum dehydrate for 2h, then cool to room temperature, then add 10g of silane coupling agent A-1170, 7g of defoaming agent, 0.3g of dibutyltin dilaurate, and 0.2g of polyamide, mix well and disperse evenly.

[0070] Example 7

[0071] The two-component transparent polyurethane potting adhesive of this embodiment includes component A and component B, and the mass ratio of component A to component B is 1:1; component A mainly consists of terminal isocyanate isocyanate prepolymer, dioctyl phthalate (DOP), flame retardant TCP, antioxidant 1010, vinyl triethoxy silane and bismuth carboxylate; component A is prepared by a method comprising the following steps:

[0072] Add 200g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 180mgKOH / g and an average functionality of 2.5, 133g of DOP, 80g of flame retardant TCP, and 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 527g of MDI-50, stir and react at 68°C under vacuum for 3h, then add about 0.05g of bismuth carboxylate, continue to stir and react at 68°C under vacuum for 1h, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 15%.

[0073] Component B consists of castor oil-based phthalic anhydride polyester polyol, dioctyl terephthalate (DOTP), silane coupling agent A-1170, defoamer, fluorinated surfactant, dibutyltin dilaurate and polyamide; component B is prepared by a method comprising the following steps:

[0074] Take 851g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 220mgKOH / g and an average functionality of 2.7, and 130g of DOTP, heat and vacuum dehydrate for 2h, then cool to room temperature, then add 10g of silane coupling agent A-1170, 7g of defoaming agent, 3g of fluorinated surfactant, 0.3g of dibutyltin dilaurate, and 0.2g of polyamide, mix well and disperse evenly.

[0075] The color of the two-component transparent polyurethane potting glue in the above Examples 1 to 7 is light yellow and transparent.

[0076] Example 8

[0077] The preparation method of the two-component transparent polyurethane potting adhesive of this embodiment includes the steps of preparing component A and preparing component B. The steps of preparing component A and component B are the same as those of embodiments 1 to 7 and will not be repeated here.

[0078] Comparative Example 1

[0079] The two-component polyurethane potting adhesive of this comparative example comprises component A and component B, and the mass ratio of component A to component B is 1:1; wherein component A is prepared by a method comprising the following steps:

[0080] Add 80g of polyether diol (molecular weight of 400), 120g of polyether diol (molecular weight of 1000), 133g of DOP, 80g of flame retardant TCP, 30g of E51, 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 527g of MDI-50, stir and react for 3h under vacuum at 68°C, then add about 0.05g of bismuth carboxylate, continue to stir and react for 1h under vacuum at 68°C, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 15%.

[0081] Component B is prepared by a method comprising the following steps: 851 g of castor oil-based phthalic anhydride polyester polyol having a hydroxyl value of 220 mgKOH / g and an average functionality of 2.7 and 130 g of DOTP are taken, heated and vacuum dehydrated for 2 hours, cooled to room temperature, and then 10 g of silane coupling agent A-1170, 7 g of defoaming agent, 3 g of fluorinated surfactant, 0.3 g of dibutyltin dilaurate, and 0.2 g of polyamide are added, and the mixture is fully mixed and dispersed uniformly.

[0082] Comparative Example 2

[0083] The two-component polyurethane potting adhesive of this comparative example comprises component A and component B, and the mass ratio of component A to component B is 1:1; wherein component A is prepared by a method comprising the following steps:

[0084] Add 200g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 180mgKOH / g and an average functionality of 2.5, 133g of DOP, 80g of flame retardant TCP, 30g of E51, and 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 527g of MDI-50, stir and react for 3h under vacuum at 68°C, then add about 0.05g of bismuth carboxylate, continue to stir and react for 1h under vacuum at 68°C, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 15%.

[0085] Component B is prepared by a method comprising the following steps: taking 263 g of polyether triol (molecular weight of 500), 588 g of polyether triol (molecular weight of 1000), and 130 g of DOTP, heating and vacuum dehydrating for 2 hours, cooling to room temperature, and then adding 10 g of silane coupling agent A-1170, 7 g of defoaming agent, 3 g of fluorine-containing surfactant, 0.3 g of dibutyltin dilaurate, and 0.2 g of polyamide, and mixing and dispersing them evenly.

[0086] Comparative Example 3

[0087] The two-component polyurethane potting adhesive of this comparative example comprises component A and component B, and the mass ratio of component A to component B is 1:1; wherein component A is prepared by a method comprising the following steps:

[0088] Add 200g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 180mgKOH / g and an average functionality of 2.5, 133g of DOP, 80g of flame retardant TCP, 30g of E51, and 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 572g of polymethylene polyphenyl isocyanate (PAPI), stir and react for 3h under vacuum at 68°C, then add about 0.05g of bis(thiocarboxylate), continue to stir and react for 1h under vacuum at 68°C, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 15%.

[0089] Component B is prepared by a method comprising the following steps: 851 g of castor oil-based phthalic anhydride polyester polyol having a hydroxyl value of 220 mgKOH / g and an average functionality of 2.7 and 130 g of DOTP are taken, heated and vacuum dehydrated for 2 hours, cooled to room temperature, and then 10 g of silane coupling agent A-1170, 7 g of defoaming agent, 3 g of fluorinated surfactant, 0.3 g of dibutyltin dilaurate, and 0.2 g of polyamide are added, and the mixture is fully mixed and dispersed evenly.

[0090] Comparative Example 4

[0091] The two-component polyurethane potting adhesive of this comparative example comprises component A and component B, and the mass ratio of component A to component B is 1:1; wherein component A is prepared by a method comprising the following steps:

[0092] Add 200g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 180mgKOH / g and an average functionality of 2.5, 133g of DOP, 80g of flame retardant TCP, 30g of E51, and 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 610g of carbodiimide-modified MDI, stir and react at 68°C under vacuum for 3h, then add about 0.05g of bismuth carboxylate, continue to stir and react at 68°C under vacuum for 1h, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 15%.

[0093] Component B is prepared by a method comprising the following steps: 851 g of castor oil-based phthalic anhydride polyester polyol having a hydroxyl value of 220 mgKOH / g and an average functionality of 2.7 and 130 g of DOTP are taken, heated and vacuum dehydrated for 2 hours, cooled to room temperature, and then 10 g of silane coupling agent A-1170, 7 g of defoaming agent, 3 g of fluorinated surfactant, 0.3 g of dibutyltin dilaurate, and 0.2 g of polyamide are added, and the mixture is fully mixed and dispersed evenly.

[0094] Comparative Example 5

[0095] The two-component polyurethane potting adhesive of this embodiment includes component A and component B, and the mass ratio of component A to component B is 1:1; component A mainly consists of terminal isocyanate isocyanate prepolymer, dioctyl phthalate (DOP), flame retardant TCP, NPEF-170 bisphenol F type epoxy resin, antioxidant 1010, vinyl triethoxy silane and bis(carboxylate); component A is prepared by a method comprising the following steps:

[0096] Add 150g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 230mgKOH / g and an average functionality of 3.0, 153g of (DOP), 80g of flame retardant TCP, 30g of NPEF-170 bisphenol F epoxy resin, and 10g of antioxidant 1010 to a three-necked flask, heat to 120°C, and stir and dehydrate for 2h under vacuum, then cool to 65°C, add 553g of MDI-50, stir and react at 68°C under vacuum for 3h, then add about 0.05g of bis(carboxylate), continue to stir and react at 68°C under vacuum for 1h, then cool to 60°C, release the vacuum with nitrogen, add 20g of vinyl triethoxysilane, and continue to stir for 10min. The NCO% value of the test component A is 16%.

[0097] Component B consists of castor oil-based phthalic anhydride polyester polyol, dioctyl phthalate (DOP), silane coupling agent KH-560, defoamer, fluorinated surfactant, dibutyltin dilaurate and polyamide; component B is prepared by a method comprising the following steps:

[0098] Take 890g of castor oil-based phthalic anhydride polyester polyol with a hydroxyl value of 210mgKOH / g and an average functionality of 2.5, and 90g of DOP. Heat and vacuum dehydrate for 2h, then cool to room temperature, then add 15g of silane coupling agent KH-560, 7g of defoaming agent, 3g of fluorinated surfactant, 0.3g of dibutyltin dilaurate, and 0.2g of polyamide, mix well and disperse evenly.

[0099] Experimental example

[0100] 1) The viscosities of component A and component B of the two-component polyurethane potting adhesives of Examples 1 to 7 and Comparative Examples 1 to 5 at 23° C. were tested respectively. The results are shown in Table 1.

[0101] Table 1 Viscosity test results of each component of the embodiment and the comparative example (unit: cp, 23°C)

[0102]

[0103] It can be seen from Table 1 that the viscosities of the component A and the component B of the two-component polyurethane potting adhesives of the embodiment and the comparative example are both relatively low.

[0104] 2) Component A and component B of the two-component polyurethane potting adhesives of Examples 1 to 7 and Comparative Examples 1 to 5 were mixed uniformly at a mass ratio of 1:1, and then their transparency was tested using GB / T 1721-2008 "Test method for appearance and transparency of varnishes, clear oils and thinners". The results are shown in Table 2.

[0105] Table 2 Transparency test results

[0106]

[0107] It can be seen from Table 2 that the two-component polyurethane potting glue in Comparative Examples 3 and 4 using polyisocyanate to synthesize prepolymers and Comparative Example 5 using castor oil-based phthalic anhydride polyester polyol with an average functionality of 3 to synthesize prepolymers is turbid after being evenly mixed and cannot achieve a transparent effect.

[0108] 3) The volume resistivity of the two-component polyurethane potting glue of the embodiment and the comparative example (component A and component B were mixed in a mass ratio of 1:1 during the test) at 23°C and 90°C was measured using a ZC-90G high insulation resistance meter (produced by Shanghai Taiou Electronics Co., Ltd.). The results are shown in Table 3.

[0109] Table 3 Volume resistivity test results of the embodiments and comparative examples (unit: Ω·cm)

[0110] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 23℃ <![CDATA[2.64*10 14 ]]> <![CDATA[4.56*10 14 ]]> <![CDATA[3.79*10 14 ]]> <![CDATA[3.73*10 14 ]]> <![CDATA[4.02*10 14 ]]> <![CDATA[3.72*10 14 ]]> <![CDATA[3.23*10 14 ]]> <![CDATA[4.35*10 13 ]]> <![CDATA[2.01*10 13 ]]> 90℃ <![CDATA[5.13*10 13 ]]> <![CDATA[3.78*10 13 ]]> <![CDATA[7.26*10 13 ]]> <![CDATA[7.23*10 13 ]]> <![CDATA[7.98*10 13 ]]> <![CDATA[7.15*10 13 ]]> <![CDATA[2.84*10 13 ]]> <![CDATA[4.03*10 12 ]]> <![CDATA[2.33*10 11 ]]>

[0111] It can be seen from Table 3 that the sample in Comparative Example 1 uses ordinary polyether synthetic prepolymer, and the sample in Comparative Example 2 uses ordinary polyether as a polyhydroxy curing agent. The volume resistivity at room temperature is relatively small, and the volume resistivity drops significantly at 90°C, while the volume resistivity of the samples of Examples 1 to 6 does not drop significantly at high temperature; since no epoxy resin is added to component A of the sample in Example 7, although the resistivity at 90°C drops significantly compared to that at room temperature, the volume resistivity at room temperature and 90°C is relatively large.

[0112] 4) Use the two-component polyurethane potting glue of the embodiment and comparative example (component A and component B are mixed in a mass ratio of 1:1 during the test) to weld two wires to the PCB circuit board. At this time, use a multimeter to connect the two ends of the wires, and the test resistance display is ∞. Then put this circuit board into a plastic shell with the wires exposed to the outside, and inject the mixed two-component potting glue until the PCB circuit board is completely submerged. After the potting glue is cured, put it into a high temperature and high humidity box at 85°C and a relative humidity of 85%. Expose the end of the wire to the outside of the high temperature and high humidity box, and use a multimeter to connect the two ends of the wire at any time to test the resistance value. When the insulation performance of the potting glue decreases, the resistance value can be displayed on the multimeter. If the insulation level can still be achieved (that is, the resistance is 4*10 12 Ω or more), the value displayed on the multimeter is ∞. The results of the embodiments and comparative examples using the above method to test the resistance value of the potted test piece under the "double 85" condition are shown in Table 4.

[0113] Table 4 Resistance test results of potted specimens of the embodiment and the comparative example under the "double 85" condition

[0114]

[0115] It can be seen from Table 4 that the sample in Comparative Example 1 uses ordinary polyether to synthesize the prepolymer, and the sample in Comparative Example 2 uses ordinary polyether as the polyhydroxy curing agent. The insulation performance is maintained for a very short time under the "double 85" condition, while the two-component low-viscosity transparent polyurethane potting glue of the embodiment is also excellent in high temperature and high humidity, which proves that the invention has the characteristics of excellent electrical properties at high temperature and can have a longer service life.

Claims

1. A two-component transparent polyurethane potting adhesive, characterized in that: The invention comprises component A and component B; component A comprises an isocyanate-terminated polyurethane prepolymer; the isocyanate-terminated polyurethane prepolymer is produced by the reaction of an aromatic diisocyanate monomer and a castor oil-based phthalic anhydride polyester polyol; component B comprises a polyhydroxy curing agent and an organic metal catalyst; the polyhydroxy curing agent is castor oil and / or castor oil-based phthalic anhydride polyester polyol.

2. The two-component transparent polyurethane potting adhesive according to claim 1, characterized in that: The component A also includes epoxy resin; the mass ratio of the epoxy resin to the castor oil-based phthalic anhydride polyester polyol used to generate the isocyanate-terminated polyurethane prepolymer is 3-5:15-30.

3. The two-component transparent polyurethane potting adhesive according to claim 2, characterized in that: The epoxy resin is a liquid epoxy resin; the epoxy resin is a bisphenol A epoxy resin and / or a bisphenol F epoxy resin.

4. The two-component transparent polyurethane potting adhesive according to claim 1, 2 or 3, characterized in that: The mass ratio of castor oil-based phthalic anhydride polyester polyol and aromatic diisocyanate monomer used to generate the isocyanate-terminated polyurethane prepolymer is 150-300:410-600; the hydroxyl value of castor oil-based phthalic anhydride polyester polyol used to generate the isocyanate-terminated polyurethane prepolymer is 160-230 mgKOH / g, and the average functionality is 2.0-2.

5.

5. The two-component transparent polyurethane potting adhesive according to claim 1, 2 or 3, characterized in that: The isocyanate-terminated polyurethane prepolymer is formed by reacting castor oil-based phthalic anhydride polyester polyol and aromatic diisocyanate monomer at 65-70° C. for 2-3 hours under vacuum conditions, then adding a catalyst and continuing to react at 65-70° C. for 1-1.5 hours under vacuum conditions.

6. The two-component transparent polyurethane potting adhesive according to claim 1, 2 or 3, characterized in that: The component A also includes an adhesion promoter; the mass ratio of the adhesion promoter to the castor oil-based phthalic anhydride polyester polyol used to generate the isocyanate-terminated polyurethane prepolymer is 1.5-3.5:15-30.

7. The two-component transparent polyurethane potting adhesive according to claim 6, characterized in that: In component A, the adhesion promoter is a vinyl silane adhesion promoter.

8. The two-component transparent polyurethane potting adhesive according to claim 1, 2 or 3, characterized in that: The component A also includes additives; the additives include plasticizers, flame retardants and antioxidants; in component A, the mass ratio of the plasticizer to the castor oil-based phthalic anhydride polyester polyol used to generate the terminal isocyanate polyurethane prepolymer is 1:0.75-3.3, the mass ratio of the flame retardant to the plasticizer is 1:1-4, and the mass of the antioxidant is 0.5%-1% of the total mass of component A and component B.

9. The two-component transparent polyurethane potting adhesive according to claim 1, 2 or 3, characterized in that: The component B further comprises a substrate wetting agent; the substrate wetting agent is an organic silicon nonionic surfactant and / or a fluorine-containing surfactant.

10. A method for preparing a two-component transparent polyurethane potting adhesive as claimed in any one of claims 1 to 9, characterized in that: The method comprises the following steps: dehydrating a material whose main component is castor oil-based phthalic anhydride polyester polyol, reacting the material with an aromatic diisocyanate monomer at 65-70°C for 2-3 hours under vacuum conditions, adding a catalyst, continuing to react at 65-70°C for 1-1.5 hours under vacuum conditions, adding an adhesion promoter after cooling, and mixing to obtain component A; dehydrating a material whose main component is a polyhydroxy curing agent, adding an additional material, and mixing to obtain component B; the additional material comprises an organic metal catalyst.

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