Single-component polyurethane sealant and preparation method thereof

Abstract

The invention discloses a single-component polyurethane sealant and a preparation method thereof, and the single-component polyurethane sealant comprises the following components by mass: 60-66% of a prepolymer, 29-32% of a filler, 1-2% of a water removal agent, 3-5% of a plasticizer A, and 0.0066-0.016% of a catalyst A. The invention further discloses a preparation method of the single-component polyurethane sealant. According to the invention, the 4, 4 '-MDI type prepolymer with low viscosity and low free isocyanate monomer content is used as a basic prepolymer, the single-component polyurethane sealant with excellent comprehensive performance is provided under the condition that various additives such as antioxidants and ultraviolet absorbents are not added, the single-component polyurethane sealant is applied to bonding of organic glass and a machine body, and the service life of the sealant is prolonged. According to the present invention, the prepared adhesive has characteristics of excellent adhesion, excellent sag resistance (0 mm), high body strength (tensile strength > = 10 MPa), high bonding strength (tensile shear strength > = 6 MPa), and can meet the requirements of complex comprehensive environments (such as solar radiation-damp heat-salt mist, high temperature-low temperature-high and low temperature impact) (the tensile shear strength after the environmental test > = 4.0 MPa).

Description

Technical Field

[0001] The invention belongs to the field of polyurethane sealants, and relates to the preparation and application of a single-component polyurethane sealant for bonding organic glass to a fuselage. Background Art

[0002] Aerospace organic glass is a colorless transparent thermoplastic formed by the polymerization of methyl methacrylate. It has long been used as a commonly used transparent material on aircraft. One way to connect aviation organic glass with fuselage materials is to use adhesives to connect the transparent parts with the fuselage materials, which has the effects of buffering, shock absorption, sealing and bonding.

[0003] CN114672271B reports an epoxy structural adhesive film for bonding aviation organic glass to polyester steel and a preparation method thereof, but the adhesive film needs to be cured at 85°C, and the epoxy adhesive has high hardness and brittleness after curing.

[0004] CN103881071B reports a polyester polyol for bonding aviation plexiglass to polyester ribbon and a two-component polyurethane adhesive prepared therefrom. Component A is a liquid polyol component and component B is a polyisocyanate curing agent. The two need to be mixed evenly during use, and the construction process is relatively complicated.

[0005] In addition, during the flight of the aircraft, the edge bonding area of ​​the plexiglass is exposed to a harsh working environment and must withstand extreme temperature gradients, cyclic loads, stress concentration, and even external humidity, heat, salt spray, etc. Therefore, the adhesive also needs to have good weather resistance.

[0006] CN103834345B, CN105255433A, and CN107556961A all use aliphatic isocyanates and light stabilizers, antioxidants, ultraviolet absorbers, etc. to improve the weather resistance of polyurethane sealants. However, most of these functional additives contain amino groups, which are not conducive to the storage stability of single-component polyurethane sealants.

[0007] CN116042163A adopts the method of adding modified halloysite filler, loading antioxidant on the halloysite filler, and supplemented with ultraviolet absorber. After 300 h of wet heat aging and 2000 h of ultraviolet aging, the bulk strength and color fastness of the sealant with halloysite added do not decrease significantly. However, the preparation process of the modified particles is complicated, the strength of the sealant is low (the tensile strength before aging is less than 3 MPa), and the ultraviolet absorber (most of which contains amino groups) is not conducive to the storage stability of the sealant. Summary of the invention

[0008] In order to solve the above problems, the present invention uses a 4,4′-MDI type prepolymer with low viscosity and low free isocyanate monomer content as a basic prepolymer, and provides a one-component polyurethane sealant with excellent comprehensive performance without adding various antioxidants, ultraviolet absorbers and other additives. The sealant is applied to the bonding of organic glass to the fuselage, has excellent anti-sagging property (0 mm), high body strength (tensile strength ≥10 MPa), high bonding strength (tensile shear strength ≥6 MPa), and can meet the requirements of complex comprehensive environments (such as solar radiation-humid heat-salt spray, high temperature-low temperature-high and low temperature impact) (tensile shear strength after environmental testing ≥4.0 MPa).

[0009] The first aspect of the present invention provides a one-component polyurethane sealant, comprising the following components: ; The method for preparing the prepolymer comprises the following steps: (1) Add polyether polyol, plasticizer B and 4,4′-MDI and react without a catalyst; (2) When the molar amount of OH in the reaction system is consumed by 35% to 50%, catalyst B is added to continue the reaction; (3) When the NCO% content reaches the theoretical value, add stabilizer, mix evenly, and discharge.

[0010] The one-component polyurethane sealant does not contain antioxidants and ultraviolet absorbers.

[0011] The molar ratio of OH in the polyether polyol to NCO in 4,4′-MDI is selected from 0.35 to 0.65.

[0012] The polyether polyol is selected from one or more of polyethylene oxide polyol (PEG), polypropylene oxide polyol (PPG), polytetramethylene oxide polyol (PTMG), and the molecular weight of the polyether polyol is preferably 2000 to 20000. Polypropylene oxide polyol terminated with ethylene oxide (PPG-PEG) is preferred, and polypropylene oxide diol, polypropylene oxide triol or a combination thereof having a number average molecular weight in the range of 2000 to 8000 is particularly preferred.

[0013] The plasticizer B is one or more of chlorinated paraffin, organic carboxylic acid ester, alkyl phenyl sulfonate, and propylene carbonate, and the amount of the plasticizer B is 10% to 15% of the prepolymer mass. The plasticizer B is preferably an organic carboxylic acid ester, and the amount of the plasticizer B is preferably 10% to 12% of the prepolymer mass.

[0014] The 4,4′-MDI preferably has a 4,4 '-MDI content of ≥95%, and more preferably 4,4 '-MDI ≥97.5%.

[0015] The catalyst B is a mixture of an organic amine compound and an organic metal compound, the organic amine catalyst is preferably a tertiary amino compound, such as 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), N-alkylmorpholine, N,N'-dimethylpiperazine, 4-dimethylaminopyridine, N-methylimidazole, N-vinylimidazole or 1,2-dimethylimidazole; the organic metal catalyst is preferably one or more of organic tin, organic bismuth, organic lead, organic zinc and organic mercury. The amount of the composite catalyst is preferably 0.001% to 0.003% of the mass of the prepolymer, and the mass ratio of the organic metal compound to the organic amine is preferably 1:5 to 10.

[0016] The stabilizer includes one or more of an organic acid, an inorganic acid or an acyl chloride, the inorganic acid is such as hydrochloric acid, sulfuric acid, phosphoric acid or its derivatives, the organic acid is such as formic acid, acetic acid or other alkanoic acid, the acyl chloride is such as formyl chloride, acetyl chloride, propionyl chloride and benzoyl chloride. The amount of the stabilizer is preferably 0.02% to 0.05% of the prepolymer weight.

[0017] The prepolymer NCO% ranges from 1.0% to 3.0%, preferably 1.6% to 2.5%.

[0018] In the step (1), the polyether polyol and the plasticizer B are dehydrated before use to a water content of less than 500 ppm. The dehydration process may be specifically, under stirring conditions, heating to 100°C-110°C, turning on a vacuum pump, and dehydrating for 2-3 hours.

[0019] In the step (1), the reaction temperature is preferably 75 ºC to 80 ºC, and the reaction time is preferably 2 h to 4 h.

[0020] In the step (2), the reaction temperature is preferably 75 ºC to 80 ºC, and the reaction time is preferably 30 min to 60 min.

[0021] In the preparation method of the prepolymer of the present invention, the probability of interchain reaction of the polyurethane prepolymer is effectively reduced by using step-by-step reaction and composite catalyst, thereby achieving the effect of controlling the molecular weight distribution of the polyurethane prepolymer and reducing the free isocyanate content. Compared with the prior art, the prepolymer prepared by the present invention has the following advantages: (1) the room temperature viscosity of the 4,4′-MDI type NCO-terminated prepolymer is low; (2) the free isocyanate monomer content of the 4,4′-MDI type NCO-terminated prepolymer is not higher than 0.5%wt. (3) the synthesis process of the 4,4′-MDI type NCO-terminated prepolymer is simple and easy to operate.

[0022] The filler is a mixture of a volume-increasing filler and a reinforcing filler, and the mass ratio of the volume-increasing filler to the reinforcing filler is 1:2 to 2.6. Preferably, the volume-increasing filler is one of active light calcium carbonate, active heavy calcium carbonate, nano calcium carbonate, talcum powder, silica powder, and kaolin, preferably light calcium carbonate. Preferably, the reinforcing filler is one of medium super wear-resistant carbon black, medium thermal cracking carbon black, fine thermal cracking carbon black, acetylene carbon black, and semi-reinforcing carbon black, preferably acetylene carbon black.

[0023] The dehydrating agent is one of molecular sieve powder, calcium oxide, highly reactive isocyanate (such as p-toluenesulfonyl isocyanate), monooxazolidine, orthoformate, preferably any one or a combination of two thereof.

[0024] The plasticizer A is one or a combination of two of chlorinated paraffin, organic carboxylic acid ester, alkyl phenyl sulfonate, and propylene carbonate.

[0025] The catalyst A is a mixture of an organic amine compound and an organic metal compound, the mass ratio of the organic metal compound to the organic amine compound is 2:3~2:6, the organic amine catalyst is preferably a tertiary amino compound, such as 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), N-alkylmorpholine, N,N'-dimethylpiperazine, 4-dimethylaminopyridine, N-methylimidazole, N-vinylimidazole or 1,2-dimethylimidazole; the organic metal catalyst is preferably one of organic tin, organic bismuth, organic lead, organic zinc and organic mercury.

[0026] A second aspect of the present invention provides a method for preparing a one-component polyurethane sealant, comprising the following steps: (1) Add the prepared prepolymer into a double planetary reactor, add the volume-increasing filler and the reinforcing filler in sequence, and stir and disperse; (2) Add a dewatering agent, a plasticizer, and a catalyst in sequence, stir and mix well, and obtain the one-component polyurethane sealant.

[0027] Preferably, in step (1), the stirring speed is not less than 40 r / min, the dispersion speed is not less than 800 r / min, the vacuum degree is not less than -0.95 MPa, and the stirring is carried out for 60 min to 90 min, and the system temperature is controlled to be lower than 30 °C.

[0028] Preferably, in step (2), stirring is performed under a vacuum degree not less than -0.95 MPa.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. The polyurethane sealant prepared by using self-made 4,4′-MDI prepolymer with low viscosity and low free isocyanate monomer content (less than or equal to 0.5%) can still maintain good extrusion and good mechanical properties of the polyurethane sealant under high carbon black dosage; 2. The reinforcing filler carbon black makes the polyurethane sealant have excellent weather resistance and thixotropy, and the composite use with the volume-increasing filler balances the mechanical properties and extrusion properties of the polyurethane sealant; 3. The one-component polyurethane sealant does not contain any antioxidants, ultraviolet absorbers and other additives, which improves the storage stability of the polyurethane sealant and the storage period can reach more than 9 months. DETAILED DESCRIPTION

[0030] Preparation of 4,4′-MDI prepolymer: Prepolymer 1: Add 300 g of polyether 3600 (OH: 28 mgKOH / g, f=3), 200 g of polyether DL4000D (OH: 28 mgKOH / g, f=2), and 62.4 g of didecyl phthalate (DIDP) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 61.3 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 75 °C~80 °C for 2 h, add 0.016 g of composite catalyst (dibutyltin dilaurate / dimorpholine diethyl ether=1:8), continue to react for 1 h, test NCO% is 1.68% (theoretical NCO% is 1.62%), add 0.13 g of benzoyl chloride, stir evenly, discharge, and seal for storage, which is pre-1.

[0031] Prepolymer 2: Add 300 g of polyether EP3600 (OH: 28 mgKOH / g, f=3), 200 g of polyether TED28 (OH: 28 mgKOH / g, f=2), and 76.6 g of diisononyl phthalate (DINP) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 62.0 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 75 °C~80 °C for 4 h, add 0.008 g of composite catalyst (dibutyltin dilaurate / dimorpholine diethyl ether = 1:10), continue to react for 1 h, test NCO% is 1.67% (theoretical NCO% is 1.62%), add 0.13 g of phosphoric acid, stir evenly, discharge, and seal for storage, which is pre-2.

[0032] Prepolymer 3: Add 300 g of polyether 2802 (OH: 28 mgKOH / g, f=3), 100 g of polyether DL2000D (OH: 56 mgKOH / g, f=2), and 50.9 g of alkyl sulfonate phenyl ester (T50) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 58.5 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 75 °C~80 °C for 4 h, add 0.013 g of composite catalyst (dibutyltin dilaurate / N-vinylmorpholine=1:8), continue to react for 1 h, test NCO% is 2.01% (theoretical NCO% is 2.06%), add 0.13 g of acetyl chloride, stir evenly, discharge, and seal for storage, which is pre-3.

[0033] Prepolymer 4: Add 300 g of polyether 2802 (OH: 28 mgKOH / g, f=3), 200 g of polyether DL4000D (OH: 28 mgKOH / g, f=2), and 64.2 g of alkyl sulfonate phenyl ester (T50) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 77.8 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 75 °C~80 °C for 4 h, add 0.018 g of composite catalyst (dibutyltin dilaurate / N-vinylmorpholine=1:10), continue to react for 1 h, test NCO% is 2.47% (theoretical NCO% is 2.43%), add 0.33 g of phosphoric acid, stir evenly, discharge, and seal for storage, which is pre-4.

[0034] Prepolymer 5: Add 350 g of polyether TEP240 (OH: 24 mgKOH / g, f=3), 200 g of polyether TED28 (OH: 28 mgKOH / g, f=2), and 68.2 g of diisononyl phthalate (DINP) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 64.2 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 75 °C~80 °C for 3 h, add 0.018 g of composite catalyst (bismuth isooctanoate / dimorpholine diethyl ether=1:5), continue to react for 1 h, test NCO% is 1.73% (theoretical NCO% is 1.62%), add 0.13 g of benzoyl chloride, stir evenly, discharge, and seal for storage, which is pre-5.

[0035] Prepolymer 6: Add 350 g of polyether TEP240 (OH: 24 mgKOH / g, f=3) and 42.6 g of diisononyl phthalate (DINP) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 33 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 75 °C~80 °C for 3 h, add 0.010 g of composite catalyst (bismuth isooctanoate / N-vinylmorpholine=1:5), continue to react for 1 h, test NCO% is 1.65% (theoretical NCO% is 1.62%), add 0.13 g of benzoyl chloride, stir evenly, discharge, and seal for storage, which is pre-6.

[0036] Prepolymer 7: Add 480 g of polyether 330N (OH: 35 mgKOH / g, f=3), 200 g of polyether DL4000D (OH: 56 mgKOH / g, f=2), and 87.2 g of alkyl sulfonate phenyl ester (T50) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 104.5 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 70 °C~75 °C for 3 h, add 0.12 g of composite catalyst (T12 / DBU=1:10), continue to react for 1 h, measure NCO% as 1.75 (theoretical NCO% is 1.62), add 0.13 g of benzoyl chloride, stir evenly, discharge, and seal for storage, which is pre-7.

[0037] Prepolymer 8: Add 300 g of polyether 3600 (OH: 28 mgKOH / g, f=3), 200 g of polyether DL4000D (OH: 28 mgKOH / g, f=2), and 62.4 g of didecyl phthalate (DIDP) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 61.3 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 75 °C~80 °C for 2 h, add 0.016 g of composite catalyst (bismuth isooctanoate / N-vinylmorpholine=1:2), continue to react for 1 h, test NCO% is 1.61% (theoretical NCO% is 1.62%), add 0.33 g of phosphoric acid, stir evenly, discharge, and seal for storage to obtain D-pre-1.

[0038] Prepolymer 9: Add 300 g of polyether 3600 (OH: 28 mgKOH / g, f=3), 200 g of polyether DL4000D (OH: 28 mgKOH / g, f=2), and 62.4 g of diisononyl phthalate (DINP) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 61.3 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 75 °C~80 °C for 2 h, add 0.016 g of composite catalyst (dibutyltin dilaurate / N-vinylmorpholine=1:15), continue to react for 1 h, test NCO% is 1.99% (theoretical NCO% is 1.62%), add 0.33 g of phosphoric acid, stir evenly, discharge, and seal for storage to obtain D-pre-2.

[0039] Prepolymer 10: Add 300 g of polyether 2802 (OH: 28 mgKOH / g, f=3), 200 g of polyether DL4000D (OH: 28 mgKOH / g, f=2), and 62.4 g of didecyl phthalate (DIDP) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool to 70 °C, add 61.3 g of diphenylmethane diisocyanate (4,4′-MDI≥99%), react at 75 °C~80 °C for 5 h (OH consumption is 58.5%), add 0.008 g of composite catalyst (dibutyltin dilaurate / dimorpholine diethyl ether=1:8), continue to react for 1 h, test NCO% is 1.63% (theoretical NCO% is 1.62%), add 0.13 g of benzoyl chloride, stir evenly, discharge, and seal for storage to obtain D-pre-3.

[0040] Prepolymer 11: (Low free synthesis process) Add 300 g of polyether 2802 (OH: 28 mgKOH / g, f=3) into the reaction bottle, dehydrate at 100 °C~110 °C for 2 h, cool down by 70 °C, design NCO / OH to be 8:1 (molar ratio), add 150 g of diphenylmethane diisocyanate (4,4′-MDI≥99%) and 0.036 g of dibutyltin dilaurate, react at 75 °C~80 °C for 3 h, remove free MDI monomer by thin film evaporator, and obtain 4,4′-MDI-polyether triol prepolymer with NCO% of 1.97%.

[0041] Similarly, 200 g of polyether DL4000D (OH: 28 mgKOH / g, f=2) was added to the reaction bottle, dehydrated at 100 °C~110 °C for 2 h, cooled by 70 °C, designed NCO / OH to be 8:1 (molar ratio), 100 g of diphenylmethane diisocyanate (4,4′-MDI≥99%) and 0.025 g of dibutyltin dilaurate were added, reacted at 75 °C~80 °C for 3 h, and free MDI monomer was removed by a thin film evaporator to obtain a 4,4′-MDI-polyether diol prepolymer with an NCO% of 1.87%.

[0042] The two prepolymers were mixed, and 10% of the total weight of plasticizer DIDP was added and mixed evenly to obtain a mixed 4,4′-MDI polyether prepolymer, D-pre-4.

[0043] Prepolymer performance test: NCO content is measured according to GB / T12009.4-1989; The viscosity is measured according to GB / T12008.7-2010, and the measuring temperature is 25°C; The content of free diisocyanate monomers was determined by gel permeation chromatography.

[0044] The test results are shown in the following table:

[0045] It can be seen from the data of pre-1~7 that the free monomer content of the synthesized low NCO prepolymer can be controlled within 0.5% by using the process of the present invention. D-pre-1~2 indicates that there are too many organic tin catalysts or too many amine catalysts, the viscosity of the prepolymer is too high or the reaction cannot be carried out thoroughly, and the free monomer content is relatively high. pre-1, pre-1, and D-pre-3 illustrate that the process needs to select a suitable catalyst addition time according to the progress of the reaction. When the consumption of hydroxyl groups in the system exceeds 50%, the interchain reaction increases, the viscosity of the prepolymer increases, and the free monomer content also increases accordingly. D-pre-4 adopts a low-free synthesis process and removes excess isocyanate monomers by thin film evaporation. Although the monomer content is low, the reaction is not thorough and the process is complicated.

[0046] Preparation of polyurethane sealant: Example 1

[0047] Add 200 g of the prepared prepolymer pre-1 into a double planetary reactor, and then add 30 g of active light calcium carbonate and 60 g of Cabot M570 carbon black in sequence. Stir at 40 r / min, dispersing speed 800 r / min, vacuum degree -0.97 MPa, stir for 60 min, and control the system temperature below 30 °C.

[0048] Then, 3 g of p-toluenesulfonyl isocyanate, 9 g of didecyl phthalate (DIDP), 0.02 g of dibutyltin dilaurate, and 0.03 g of dimorpholine diethyl ether (DMDEE) were added in sequence, and the mixture was stirred and mixed under a vacuum degree of not less than 0.1 MPa to obtain the one-component polyurethane sealant.

[0049] Example 2

[0050] Add 200 g of the prepared prepolymer pre-5 into a double planetary reactor, and then add 30 g of nano calcium carbonate and 65 g of Cabot M580 carbon black in sequence. Stir at a speed of 50 r / min, a dispersion speed of 1000 r / min, a vacuum degree of -0.97 MPa, stir for 60 min, and control the system temperature below 30 °C.

[0051] Then, 3 g of p-orthoformate, 12 g of isononyl phthalate (DINP), 0.02 g of dibutyltin dilaurate, and 0.06 g of N-vinylmorpholine were added in sequence, and the mixture was stirred and mixed under a vacuum degree of not less than 0.1 MPa to obtain the one-component polyurethane sealant.

[0052] Example 3

[0053] Add 180 g of the prepared prepolymer pre-7 into a double planetary reactor, and add 30 g of 2000 mesh talc and 60 g of Cabot CSX865 carbon black in sequence. Stir at 40 r / min, dispersing speed 1000 r / min, vacuum degree -0.97 MPa, stir for 90 min, and control the system temperature below 30 °C.

[0054] Then, 3 g of monooxazolidine (ALT201), 15 g of propylene carbonate, 0.02 g of bismuth isooctanoate, and 0.03 g of dimorpholine diethyl ether (DMDEE) were added in sequence, and the mixture was stirred and mixed under a vacuum degree of -0.97 MPa to obtain the one-component polyurethane sealant.

[0055] Comparative Example 1 The activated light calcium carbonate 30 g and Cabot M570 carbon black 60 g in Example 1 were replaced with activated light calcium carbonate 40 g and Cabot M570 carbon black 50 g, and the remaining operations were the same as in Example 1.

[0056] Comparative Example 2 The activated light calcium carbonate 30 g and Cabot M570 carbon black 60 g in Example 1 were replaced with activated light calcium carbonate 150 g, and the remaining operations were the same as in Example 1.

[0057] Comparative Example 3 The activated light calcium carbonate 30 g and Cabot M570 carbon black 60 g in Example 1 were replaced with activated light calcium carbonate 20 g and Cabot M570 carbon black 70 g, and the remaining operations were the same as in Example 1.

[0058] Comparative Example 4 Add 200 g of the prepared prepolymer D-pre-1 into a double planetary reactor, add 30 g of nano calcium carbonate, 65 g of Cabot M580 carbon black, stir at 60 r / min, disperse at 1000 r / min, vacuum at -0.97 MPa, stir for 60 min, and control the system temperature below 30 °C.

[0059] Then, 3 g of monooxazolidine (ALT201), 12 g of isononyl phthalate (DINP), 0.02 g of dibutyltin dilaurate, and 0.03 g of dimorpholine diethyl ether (DMDEE) were added in sequence, and the mixture was stirred and mixed under a vacuum degree of -0.97 MPa to obtain the one-component polyurethane sealant.

[0060] Performance test of polyurethane sealant: Sample preparation: 2 mm thick test pieces were made, and the curing conditions were (23±2)℃, humidity was 50%RH, and the curing time was 7 days for mechanical property testing.

[0061] The Shore A hardness is implemented in accordance with GB / T 531.1-2008, using three layers of specimens with a thickness of not less than 6.0mm, and tested with a Shore A hardness tester.

[0062] The tensile strength is in accordance with GB / T 528-2009.

[0063] Anti-sagging: in accordance with GB / T13477.6-2002.

[0064] The extrusion performance is carried out in accordance with GB / T 13477.3-2017, the test temperature is (23±2)℃, the sample volume is 600mL, the extrusion aperture is 4mm, the gas source pressure is above 700kPa, and the extrusion pressure is (600±2.5)kPa.

[0065] The tensile shear strength is carried out in accordance with GB / T 7124-2008. The substrate used for the bonding sample is a composite material of organic glass and epoxy. Before gluing, the surface of the substrate is treated with a commercially available primer J-485 from the Petrochemical Research Institute of Heilongjiang Academy of Sciences. The curing conditions of the bonding sample are (23±2)℃, humidity is 50%RH, and the curing time is 7 days.

[0066] The test method for shear strength after aging is: the sample is subjected to solar radiation, heat and humidity aging, and salt spray aging in accordance with GB / T7124-2008.

[0067] Weathering aging test: The preparation of bonding samples is the same as that of tensile shear samples, and the curing conditions are also the same.

[0068] The solar radiation is carried out in accordance with GJB 150.7A-2009, and the specific conditions are: temperature: 49 °C, irradiance: 1120W / m2, light time: 20 h, dark time: 4 h, one cycle is 24 h, and a total of 10 cycles.

[0069] The damp heat aging is carried out in accordance with GJB 150.9A-2009, and the specific conditions are: cycling between 30 °C, 95% RH and 60 °C, 95% RH, one cycle for 24 h, and a total of 10 cycles.

[0070] The salt spray aging is carried out in accordance with GJB 150.11A-2009, and the specific conditions are: salt spray stage, temperature 35 ° C, 5% NaCl solution, pH 6.8, salt spray deposition rate 1.5 mL / 80 cm2×h, aging time 24 h; drying stage, temperature 23 ° C, relative humidity 45% RH, test time 24 h; a total of 5 cycles.

[0071] Table 1 shows the mechanical properties and weather resistance thermal test results of the polyurethane sealants obtained in Examples 1 to 3 and Comparative Examples 1 to 5.

[0072] Table 1 Test data of polyurethane sealant bulk performance and aging performance (CF represents 100% cohesive failure, AF represents interfacial failure, and HF represents mixed failure)

[0073] The data of Examples 1 to 3 show that the polyurethane sealant prepared by using a prepolymer with low viscosity and low free isocyanate monomer content has good extrudability, excellent anti-sagging property, high body strength and good bonding performance. By comparing Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that carbon black plays a triple role of thixotropy, reinforcement and weather resistance in the system. When the amount of carbon black is reduced or no carbon black is used, the anti-sagging performance decreases. At the same time, after the environmental resistance test, cohesive failure cannot be achieved, and the interfacial force between the glue and the primer is destroyed. Comparative Example 3 shows that further increasing the amount of carbon black will affect the extrudability of the polyurethane sealant, and then affect its construction processability. By comparing Examples 1 to 3 and Comparative Example 4, it can be seen that the polyurethane sealant prepared by using a prepolymer with low viscosity and low free isocyanate monomer content has obvious advantages in extrudability and is easy to construct.

Claims

1. A one-component polyurethane sealant comprising the following components: ； The method for preparing the prepolymer comprises the following steps: (1) Add polyether polyol, plasticizer B and 4,4′-MDI and react without a catalyst; (2) When the molar amount of OH in the reaction system is consumed by 35% to 50%, catalyst B is added to continue the reaction; (3) When the NCO% content reaches the theoretical value, add stabilizer, mix evenly, and discharge.

2. The one-component polyurethane sealant according to claim 1, characterized in that: The molar ratio of OH in the polyether polyol to NCO in 4,4′-MDI is selected from 0.35 to 0.

65.

3. The one-component polyurethane sealant according to claim 1, characterized in that: The polyether polyol is selected from one or more of polyethylene oxide polyol (PEG), polypropylene oxide polyol (PPG), and polytetramethylene glycol (PTMG).

4. The one-component polyurethane sealant according to claim 1, characterized in that: The plasticizer B is one or more combinations of chlorinated paraffin, organic carboxylic acid ester, alkyl phenyl sulfonate, and propylene carbonate.

5. The one-component polyurethane sealant according to claim 1, characterized in that: The catalyst B is a mixture of an organic amine compound and an organic metal compound; the mass ratio of the organic metal compound to the organic amine is preferably 1:5-10.

6. The one-component polyurethane sealant according to claim 1, characterized in that: The stabilizer includes one or more of an organic acid, an inorganic acid or an acid chloride.

7. The one-component polyurethane sealant according to claim 1, characterized in that: The prepolymer NCO% ranges from 1.0% to 3.0%, preferably 1.6% to 2.5%.

8. The one-component polyurethane sealant according to claim 1, characterized in that: The filler is a mixture of a volume-increasing filler and a reinforcing filler, and the mass ratio of the volume-increasing filler to the reinforcing filler is 1:2-2.

6.

9. The one-component polyurethane sealant according to claim 1, characterized in that: The catalyst A is a mixture of an organic amine compound and an organic metal compound, and the mass ratio of the organic metal compound to the organic amine compound is 2:3-2:

6.

10. A method for preparing a one-component polyurethane sealant, comprising the following steps: (1) Add the prepared prepolymer into a double planetary reactor, add the volume-increasing filler and the reinforcing filler in sequence, and stir and disperse; (2) Add a dewatering agent, a plasticizer, and a catalyst in sequence, stir and mix well, and obtain the one-component polyurethane sealant.

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