Bio-based composite polyol for polyurethane adhesive and preparation method of bio-based composite polyol

Abstract

The invention discloses bio-based composite polyol for a polyurethane adhesive and a preparation method of the bio-based composite polyol, and belongs to the technical field of biomass polyol. The bio-based composite polyol for the polyurethane adhesive mainly comprises the following raw material components in parts by mass: 40-60 parts of a modified heat-conducting filler, 25-50 parts of flame-retardant biomass polyol and 32-50 parts of a flame retardant, the modified heat-conducting filler is obtained by modifying a heat-conducting filler with a silane coupling agent; the flame-retardant biomass polyol is obtained by exchanging vegetable oil with glyceride, reacting with dichlorophosphoric acid-2-methyl phenyl ester, and oxidizing; when the bio-based composite polyol for the polyurethane adhesive is prepared, the flame-retardant biomass polyol and the flame retardant are mixed for reaction, and then the modified heat-conducting filler is added for mixed reaction, so that the bio-based composite polyol for the polyurethane adhesive is obtained; the bio-based composite polyol for the polyurethane adhesive prepared by the preparation method disclosed by the invention is relatively good in flame retardance and thermal conductivity, and the polyurethane adhesive prepared by adopting the bio-based composite polyol for the polyurethane adhesive disclosed by the invention is relatively high in bonding strength.

Description

Technical Field

[0001] The invention relates to a bio-based composite polyol for a polyurethane adhesive and a preparation method thereof. Background Art

[0002] Due to their excellent bonding properties, good flexibility, and wide applicability, polyurethane adhesives have been widely used in various fields, including construction, automotive, electronics, and packaging. However, with the development of industrial technology and the increasing complexity of application scenarios, the shortcomings of traditional polyurethane adhesives in thermal conductivity have gradually become apparent. In particular, in applications with high thermal conductivity requirements, such as electronic packaging and heat dissipation equipment, traditional polyurethane materials have low thermal conductivity and cannot meet the requirements for efficient heat transfer, thus limiting their further application expansion.

[0003] In addition, the polyol raw materials used in traditional polyurethane adhesives are mostly derived from petrochemical products, which not only increases dependence on non-renewable resources, but also may bring certain environmental burdens. In order to address this problem, research on bio-based polyols has received widespread attention in recent years. Bio-based polyols are based on renewable resources, have the advantage of sustainable development, and can improve the performance characteristics of polyurethane materials to a certain extent. However, existing bio-based polyols still have some shortcomings, such as poor flame retardancy, which has become an important factor restricting their promotion in certain application scenarios with high safety requirements.

[0004] Therefore, it is particularly important to develop a bio-based composite polyol that can not only improve thermal conductivity but also have excellent flame retardant properties. Summary of the Invention

[0005] The purpose of the present invention is to provide a bio-based composite polyol for polyurethane adhesive and a preparation method thereof, so as to solve the technical problems mentioned in the above background technology.

[0006] The technical solution for achieving the purpose of the present invention is:

[0007] In a first aspect, the present invention provides a bio-based composite polyol for a polyurethane adhesive, wherein the raw material components mainly include 40 to 60 parts by mass of a modified thermal conductive filler, 25 to 50 parts by mass of a flame retardant biomass polyol, and 32 to 50 parts by mass of a flame retardant.

[0008] Furthermore, the thermally conductive filler includes any one of aluminum oxide, boron nitride, and aluminum nitride. Preferably, the thermally conductive filler is boron nitride.

[0009] Furthermore, the modified thermally conductive filler is obtained by modifying the thermally conductive filler with an aminosilane coupling agent.

[0010] Furthermore, the flame retardant biomass polyol is obtained by reacting vegetable oil with glycerol ester and then oxidizing it with 2-methylphenyl dichlorophosphate.

[0011] Furthermore, the flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0012] In a second aspect, a method for preparing a bio-based composite polyol for a polyurethane adhesive as described in the first aspect comprises the following preparation steps:

[0013] (1) Weighing and preparing each raw material component;

[0014] (2) Under nitrogen protection, the flame retardant weighed in step (1) is heated to 140-150° C. to melt, and then the flame retardant biomass polyol is added. After reacting at 140-150° C. for 2.5-3.5 hours, the modified thermal conductive filler is added, and ultrasonic oscillation is performed for 55-65 minutes. The reaction is continued with stirring for 2-3 hours to obtain a bio-based composite polyol for polyurethane adhesive.

[0015] Furthermore, the preparation steps of the modified thermally conductive filler are as follows: the thermally conductive filler and anhydrous ethanol are mixed and dispersed evenly in a mass ratio of 1: (1 to 5), and then 0.5% to 2% of the mass of the thermally conductive filler is added with an aminosilane coupling agent, the temperature is raised to 70 to 90° C. and reacted for 2 to 4 hours, and then statically aged for 10 to 15 hours, filtered, washed, and dried to obtain the modified thermally conductive filler.

[0016] Furthermore, the flame-retardant biomass polyol is prepared by first subjecting vegetable oil to an ester exchange reaction with glycerol to obtain a mixture of vegetable oil monoglycerides and vegetable oil diesters; then reacting the mixture of vegetable oil monoglycerides and vegetable oil diesters with 2-methylphenyl dichlorophosphate via a hydroxyl group to form a vegetable oil phosphate; then epoxidizing the unsaturated carbon-carbon double bonds in the vegetable oil phosphate and oxidizing the toluene in the vegetable oil phosphate to form benzaldehyde. The specific preparation steps are as follows:

[0017] A1. 50 parts by mass of vegetable oil, 9 to 10 parts by mass of glycerol, and 37 to 38 parts by mass of a catalyst were mixed, heated to 140 to 200°C at 2 to 4°C / min, and stirred under vacuum at -0.096 MPa for 3 to 8 hours to obtain a mixture of vegetable oil monoglycerides and vegetable oil diglycerides;

[0018] A2. Dissolve 30 parts by weight of a mixture of vegetable oil monoglycerides and vegetable oil diesters and 10-11 parts by weight of triethylamine in 260-270 parts by weight of dichloromethane. Then, add 20-22 parts by weight of 2-methylphenyl dichlorophosphate dropwise over 1 hour. The mixture is reacted at 58-62°C for 4-6 hours, filtered, and the filtrate is washed with deionized water at least three times. The organic layer is separated and the organic solvent is removed by rotary evaporation to obtain the vegetable oil phosphate.

[0019] A3. 37 parts by mass of vegetable oil phosphate, 17-18 parts by mass of m-chloroperbenzoic acid, and 190-200 parts by mass of dichloromethane were mixed and reacted at 0°C for 2.5-3.5 hours. After the reaction, the crude product was filtered and distilled under vacuum to remove the dichloromethane; the crude product was then dissolved in ethyl acetate and washed with 5% sodium sulfite solution, 5% sodium carbonate solution, and deionized water, respectively. The organic phase was rotary evaporated to remove the solvent to obtain epoxidized vegetable oil phosphate; 50 parts by mass of epoxidized vegetable oil phosphate was purged with nitrogen for protection, heated to 85-95°C, and then 3-4 parts by mass of azobisisobutyronitrile was added, followed by 35-37 parts by mass of N-chlorosuccinimide. After the reaction was allowed to react for 2-4 hours, 42-44 parts by mass of tetrabutylammonium bromide was added, the temperature was raised to 125-135°C, and then 33-35 parts by mass of water was added. The mixture was kept at reflux for 3-4 hours to obtain a flame-retardant biomass polyol.

[0020] Furthermore, in step A1, the catalyst is a basic catalyst.

[0021] Furthermore, the vegetable oil includes soybean oil, castor oil, cashew nut shell oil, rapeseed oil, and peanut oil.

[0022] Furthermore, when the bio-based composite polyol for polyurethane adhesive is used, the mass ratio of the bio-based composite polyol for polyurethane adhesive to the isocyanate monomer is 2.4 to 3:1.

[0023] By adopting the above technical solution, the present invention has the following beneficial effects:

[0024] (1) The present invention improves the thermal conductivity of the bio-based composite polyol by introducing a modified thermally conductive filler, thereby improving the thermal conductivity of the polyurethane adhesive prepared using the bio-based composite polyol, so that the polyurethane adhesive meets the thermal conductivity requirements of battery packaging and broadens the application range of the polyurethane adhesive; at the same time, the bio-based composite polyol for the polyurethane adhesive of the present invention improves the flame retardant properties of the bio-based composite polyol for the polyurethane adhesive by introducing flame retardant biomass polyol and flame retardant.

[0025] (2) The present invention uses aminosilane coupling agent to modify the thermally conductive filler, which can increase the dispersibility of the thermally conductive filler in the bio-based composite polyol used in the polyurethane adhesive, thereby preventing the thermally conductive filler from agglomerating and affecting the bonding performance of the polyurethane adhesive.

[0026] (3) The flame-retardant biomass polyol of the present invention is obtained by reacting vegetable oil with glycerol ester and then with 2-methylphenyl dichlorophosphate and oxidizing it. By introducing phosphate ester into the biomass polyol through the reaction, the flame retardancy of the flame-retardant biomass polyol is effectively improved.

[0027] (4) When the polyurethane adhesive of the present invention is prepared using the bio-based composite polyol, the flame retardant biomass polyol is first mixed with the flame retardant for reaction, and part of the flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is ring-opened and grafted with the epoxy group through the phosphorus-hydrogen bond, and more hydroxyl groups are introduced into the bio-based composite polyol for the polyurethane adhesive. Then, the modified thermal conductive filler is added for mixing reaction, and the amino group on the modified thermal conductive filler reacts with the aldehyde group in the flame retardant biomass polyol to form an imine bond, and the phosphorus-hydrogen bond on the remaining flame retardant is grafted with the imine bond to form a secondary amine group, thereby increasing the compatibility among the flame retardant, the modified thermal conductive filler, and the flame retardant biomass polyol, and effectively avoiding the problem of poor adhesion caused by poor compatibility among the flame retardant, the modified thermal conductive filler, and the flame retardant biomass polyol. At the same time, the introduction of more hydroxyl and secondary amine groups can improve the bonding performance of the polyurethane adhesive prepared using the bio-based composite polyol.

[0028] (5) The bio-based composite polyol for the polyurethane adhesive of the present invention comprises raw material components including a modified thermal conductive filler of boron nitride modified by a silane coupling agent, a flame retardant biomass polyol containing phosphate, and a flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, wherein the flame retardant biomass polyol containing phosphate and the flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide release phosphorus-containing free radicals to capture active free radicals of the combustion chain reaction, the boron nitride and silicon dioxide in the modified thermal conductive filler promote the formation of a dense carbon layer, the phosphate catalyzes carbonization, and forms a PNB-Si multi-element synergistic network, thereby improving the thermal stability of the residual carbon, thereby further improving the flame retardancy of the bio-based composite polyol. DETAILED DESCRIPTION

[0029] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with specific implementation methods.

[0030] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0031] The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0032] The particle size of the boron nitride in the examples of the present invention and the comparative examples is 3-10 μm.

[0033] Example 1

[0034] A method for preparing a bio-based composite polyol for polyurethane adhesives comprises the following steps:

[0035] (1) Weighing and preparing the raw material components: 40 parts by mass of modified thermal conductive filler, 25 parts by mass of flame retardant biomass polyol, and 32 parts by mass of flame retardant;

[0036] (2) Under nitrogen protection, the flame retardant weighed in step (1) was heated to 140° C. to melt, and then the flame retardant biomass polyol was added. After reacting at 140° C. for 2.5 hours, the modified thermal conductive filler was added, and after ultrasonic oscillation for 55 minutes, the stirring reaction was continued for 2 hours to obtain a bio-based composite polyol for polyurethane adhesive.

[0037] The preparation steps of the modified thermally conductive filler are as follows: the thermally conductive filler and anhydrous ethanol are mixed and dispersed uniformly in a mass ratio of 1:3, then an aminosilane coupling agent is added at 0.5% by mass of the thermally conductive filler, the temperature is raised to 70° C. and reacted for 2 hours, then statically aged for 10 hours, filtered, washed, and dried to obtain the modified thermally conductive filler.

[0038] The preparation steps of the flame retardant biomass polyol are as follows:

[0039] A1. 50 parts by mass of castor oil, 9 parts by mass of glycerol, and 37 parts by mass of sodium hydroxide catalyst were mixed, heated to 140 ° C at 2 ° C / min, and stirred under vacuum conditions of -0.096 MPa for 3 hours to obtain a mixture of vegetable oil monoglycerides and vegetable oil diglycerides;

[0040] A2. A mixture of 30 parts by weight of vegetable oil monoglycerides and vegetable oil diesters and 10 parts by weight of triethylamine were dissolved in 260 parts by weight of dichloromethane. 20 parts by weight of 2-methylphenyl dichlorophosphate were then added dropwise over 1 hour. The mixture was reacted at 58°C for 4 hours, filtered, and the filtrate was washed three times with deionized water. The organic layer was separated and the organic solvent was removed by rotary evaporation to obtain the vegetable oil phosphate.

[0041] A3. 37 parts by mass of vegetable oil phosphate, 17 parts by mass of m-chloroperbenzoic acid, and 190 parts by mass of dichloromethane were mixed and reacted at 0°C for 2.5 hours. After the reaction, the crude product was filtered and distilled under vacuum to remove the dichloromethane; the crude product was then dissolved in ethyl acetate and washed with 5% sodium sulfite solution, 5% sodium carbonate solution, and deionized water, respectively. The organic phase was rotary evaporated to remove the solvent to obtain epoxidized vegetable oil phosphate; 50 parts by mass of epoxidized vegetable oil phosphate was purged with nitrogen for protection, heated to 85°C, and then 3 parts by mass of azobisisobutyronitrile was added, followed by 35 parts by mass of N-chlorosuccinimide, and the reaction was carried out for 2 hours. Then, 42 parts by mass of tetrabutylammonium bromide was added, the temperature was raised to 125°C, and then 33 parts by mass of water was added. The mixture was kept warm and refluxed for 3 hours, and dried to remove water to obtain a flame-retardant biomass polyol.

[0042] When the bio-based composite polyol for polyurethane adhesive is used, the mass ratio of the bio-based composite polyol for polyurethane adhesive to the isocyanate monomer is 3:1.

[0043] Example 2

[0044] A method for preparing a bio-based composite polyol for polyurethane adhesives comprises the following steps:

[0045] (1) Weighing and preparing the raw material components: 50 parts by mass of modified thermal conductive filler, 38 parts by mass of flame retardant biomass polyol, and 40 parts by mass of flame retardant;

[0046] (2) Under nitrogen protection, the flame retardant weighed in step (1) was heated to 145° C. to melt, and then the flame retardant biomass polyol was added. After reacting at 145° C. for 3 h, the modified thermal conductive filler was added. After ultrasonic oscillation for 60 min, the stirring reaction was continued for 2.5 h to obtain a bio-based composite polyol for polyurethane adhesive.

[0047] The preparation steps of the modified thermally conductive filler are as follows: the thermally conductive filler and anhydrous ethanol are mixed and dispersed uniformly in a mass ratio of 1:4, and then an aminosilane coupling agent is added at 1.3% by mass of the thermally conductive filler. The temperature is raised to 80° C. and reacted for 3 hours, and then statically aged for 13 hours. The modified thermally conductive filler is filtered, washed, and dried to obtain the modified thermally conductive filler.

[0048] The preparation steps of the flame retardant biomass polyol are as follows:

[0049] A1. 50 parts by mass of castor oil, 9.5 parts by mass of glycerol, and 37.5 parts by mass of sodium hydroxide catalyst were mixed, heated to 170°C at 3°C / min, and stirred under vacuum at -0.096 MPa for 6 hours to obtain a mixture of vegetable oil monoglycerides and vegetable oil diglycerides;

[0050] A2. A mixture of 30 parts by weight of vegetable oil monoglycerides and vegetable oil diesters and 10.5 parts by weight of triethylamine were dissolved in 265 parts by weight of dichloromethane. 21 parts by weight of 2-methylphenyl dichlorophosphate were then added dropwise over 1 hour. The mixture was reacted at 60°C for 5 hours, filtered, and the filtrate was washed three times with deionized water. The organic layer was separated and the organic solvent was removed by rotary evaporation to obtain the vegetable oil phosphate.

[0051] A3. 37 parts by mass of vegetable oil phosphate, 17.5 parts by mass of m-chloroperbenzoic acid, and 198 parts by mass of dichloromethane were mixed and reacted at 0°C for 3 hours. After the reaction, the crude product was filtered and distilled under vacuum to remove the dichloromethane; the crude product was then dissolved in ethyl acetate and washed with 5% sodium sulfite solution, 5% sodium carbonate solution, and deionized water, respectively. The organic phase was rotary evaporated to remove the solvent to obtain epoxidized vegetable oil phosphate; 50 parts by mass of epoxidized vegetable oil phosphate was purged with nitrogen for protection, heated to 90°C, and then 3.5 parts by mass of azobisisobutyronitrile was added, followed by 36 parts by mass of N-chlorosuccinimide, and the reaction was carried out for 3 hours. Then, 43 parts by mass of tetrabutylammonium bromide was added, the temperature was raised to 130°C, and then 34 parts by mass of water was added. The mixture was kept warm and refluxed for 3.5 hours, and dried to remove water to obtain a flame-retardant biomass polyol.

[0052] When the bio-based composite polyol for polyurethane adhesive is used, the mass ratio of the bio-based composite polyol for polyurethane adhesive to the isocyanate monomer is 2.7:1.

[0053] Example 3

[0054] A method for preparing a bio-based composite polyol for polyurethane adhesives comprises the following steps:

[0055] (1) Weighing and preparing the raw material components: 60 parts by mass of modified thermal conductive filler, 50 parts by mass of flame retardant biomass polyol, and 50 parts by mass of flame retardant;

[0056] (2) Under nitrogen protection, the flame retardant weighed in step (1) was heated to 150° C. to melt, and then the flame retardant biomass polyol was added. After reacting at 150° C. for 3.5 hours, the modified thermal conductive filler was added. After ultrasonic oscillation for 65 minutes, the stirring reaction was continued for 3 hours to obtain a bio-based composite polyol for polyurethane adhesive.

[0057] The preparation steps of the modified thermally conductive filler are as follows: the thermally conductive filler boron nitride and anhydrous ethanol are mixed and dispersed uniformly in a mass ratio of 1:5, and then an aminosilane coupling agent is added at 2% by mass of the thermally conductive filler. The temperature is raised to 90° C. and reacted for 4 hours, and then statically aged for 15 hours. The modified thermally conductive filler is filtered, washed, and dried to obtain the modified thermally conductive filler.

[0058] The preparation steps of the flame retardant biomass polyol are as follows:

[0059] A1. 50 parts by mass of vegetable oil, soybean oil, 10 parts by mass of glycerol, and 38 parts by mass of sodium hydroxide catalyst were mixed, heated to 200 ° C at 4 ° C / min, and stirred under vacuum conditions of -0.096 MPa for 8 hours to obtain a mixture of vegetable oil monoglycerides and vegetable oil diglycerides;

[0060] A2. A mixture of 30 parts by weight of vegetable oil monoglycerides and vegetable oil diesters and 11 parts by weight of triethylamine were dissolved in 270 parts by weight of dichloromethane. 22 parts by weight of 2-methylphenyl dichlorophosphate were then added dropwise over 1 hour. The mixture was reacted at 62°C for 6 hours, filtered, and the filtrate was washed three times with deionized water. The organic layer was separated and the organic solvent was removed by rotary evaporation to obtain the vegetable oil phosphate.

[0061] A3. 37 parts by mass of vegetable oil phosphate, 18 parts by mass of m-chloroperbenzoic acid, and 200 parts by mass of dichloromethane were mixed and reacted at 0°C for 3.5 hours. After the reaction, the crude product was filtered and distilled under vacuum to remove the dichloromethane; the crude product was then dissolved in ethyl acetate and washed with 5% sodium sulfite solution, 5% sodium carbonate solution, and deionized water, respectively. The organic phase was rotary evaporated to remove the solvent to obtain epoxidized vegetable oil phosphate; 50 parts by mass of epoxidized vegetable oil phosphate was purged with nitrogen for protection, heated to 95°C, and then 4 parts by mass of azobisisobutyronitrile was added, followed by 37 parts by mass of N-chlorosuccinimide, and the reaction was carried out for 4 hours. Then, 44 parts by mass of tetrabutylammonium bromide was added, the temperature was raised to 135°C, and then 35 parts by mass of water was added. The mixture was kept warm and refluxed for 4 hours, and dried to remove water to obtain a flame-retardant biomass polyol.

[0062] When the bio-based composite polyol for polyurethane adhesive is used, the mass ratio of the bio-based composite polyol for polyurethane adhesive to the isocyanate monomer is 2.4:1.

[0063] Comparative Example 1

[0064] The difference between Comparative Example 1 and Example 2 is that the bio-based composite polyol for the polyurethane adhesive uses a thermally conductive filler instead of a modified thermally conductive filler, and the remaining steps and components are the same as those in Example 2.

[0065] Comparative Example 2

[0066] The difference between Comparative Example 2 and Example 2 is that no flame retardant is added to the bio-based composite polyol for the polyurethane adhesive, and the remaining steps and ingredients are the same as those in Example 2.

[0067] Comparative Example 3

[0068] The difference between Comparative Example 3 and Example 2 is that biomass polyol is used in the bio-based composite polyol for polyurethane adhesive instead of flame-retardant biomass polyol. The biomass polyol is obtained by epoxidation after exchanging vegetable oil with glycerol ester. The remaining steps and components are the same as those in Example 2.

[0069] Comparative Example 4

[0070] The difference between Comparative Example 4 and Example 2 is that the flame retardant biomass polyol is obtained by exchanging vegetable oil with glycerol, reacting with 2-methylphenyl dichlorophosphate, and epoxidizing. The remaining steps and ingredients are the same as those in Example 2.

[0071] Effect Examples

[0072] The bio-based composite polyols for polyurethane adhesives of Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to high-temperature dehydration at 120° C. for 2 h, then cooled to 80° C., and a catalyst of dibutyltin dilaurate in an amount of 0.025 times the mass of the bio-based composite polyols for polyurethane adhesive was added and mixed uniformly at high speed. Subsequently, an isocyanate monomer MDI in a corresponding mass ratio was added and vacuum stirred for 1 h to obtain a polyurethane adhesive.

[0073] The obtained polyurethane adhesive is then tested for thermal conductivity according to ASTM D5470 standard; and for flame retardancy according to UL-94-2013 standard;

[0074] PVC sheets were cut into 20cm x 2.5cm strips for testing. A certain amount of polyurethane adhesive was evenly applied to the strips using a wire rod. The strips were then dried at 70°C for 2 hours. The strips were then bonded together and heat-pressed in a 70°C oven for 30 seconds. After 5 minutes, a tensile test was performed on an electronic universal testing machine at a rate of 200 mm / min. The initial bond strength was calculated as the average of three replicates. The strips were then left at room temperature for 48 hours before the final peel strength was measured.

[0075] Table 1 below shows the performance test results of the polyurethane adhesives prepared using bio-based composite polyols in Examples 1 to 3 and Comparative Examples 1 to 4:

[0076] Table 1

[0077]

[0078]

[0079] It can be seen from Table 1 that the polyurethane adhesives prepared in Examples 1 to 3 using bio-based composite polyols have good flame retardancy, thermal conductivity and bonding properties.

[0080] The difference between Comparative Example 1 and Example 2 is that the bio-based composite polyol for polyurethane adhesive uses a thermally conductive filler instead of a modified thermally conductive filler, and the flame retardancy, thermal conductivity and bonding properties of the polyurethane adhesive prepared using the bio-based composite polyol for polyurethane adhesive are relatively weak.

[0081] The difference between Comparative Example 2 and Example 2 is that no flame retardant is added to the bio-based composite polyol for the polyurethane adhesive, and the flame retardancy and bonding properties of the polyurethane adhesive prepared using the bio-based composite polyol for the polyurethane adhesive are relatively weak.

[0082] The difference between Comparative Example 3 and Example 2 is that biomass polyol is used in the bio-based composite polyol for polyurethane adhesive instead of flame retardant biomass polyol, and the flame retardancy and bonding properties of the polyurethane adhesive prepared from the bio-based composite polyol for polyurethane adhesive are relatively weak.

[0083] The difference between Comparative Example 4 and Example 2 is that the flame-retardant biomass polyol is obtained by reacting vegetable oil with glycerol ester and then reacting with 2-methylphenyl dichlorophosphate and epoxidizing. The polyurethane adhesive prepared using bio-based composite polyol has better flame retardancy and bonding properties.

[0084] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A bio-based composite polyol for polyurethane adhesive, characterized in that: Calculated by weight, the raw material components mainly include 40 to 60 parts by weight of modified thermal conductive filler, 25 to 50 parts by weight of flame retardant biomass polyol, and 32 to 50 parts by weight of flame retardant.

2. The bio-based composite polyol for polyurethane adhesive according to claim 1, characterized in that: The modified thermally conductive filler is obtained by modifying the thermally conductive filler with an aminosilane coupling agent.

3. The bio-based composite polyol for polyurethane adhesive according to claim 1, characterized in that: The flame-retardant biomass polyol is obtained by reacting vegetable oil with glycerol ester and then oxidizing the ester with 2-methylphenyl dichlorophosphate.

4. The bio-based composite polyol for polyurethane adhesive according to claim 1, characterized in that: The flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

5. A method for preparing a bio-based composite polyol for polyurethane adhesive according to any one of claims 1 to 4, characterized in that: The method comprises the following preparation steps: (1) Weighing and preparing each raw material component; (2) Under nitrogen protection, the flame retardant weighed in step (1) is heated to 140-150° C. to melt, and then the flame retardant biomass polyol is added. After reacting at 140-150° C. for 2.5-3.5 hours, the modified thermal conductive filler is added, and ultrasonic oscillation is performed for 55-65 minutes. The reaction is continued with stirring for 2-3 hours to obtain a bio-based composite polyol for polyurethane adhesive.

6. The method for preparing a bio-based composite polyol for polyurethane adhesive according to claim 5, characterized in that: The preparation steps of the modified thermally conductive filler are as follows: the thermally conductive filler and anhydrous ethanol are mixed and dispersed uniformly in a mass ratio of 1:(1-5), then an aminosilane coupling agent is added at 0.5% to 2% by mass of the thermally conductive filler, the temperature is raised to 70-90° C., the reaction is carried out for 2-4 hours, and then the modified thermally conductive filler is aged for 10-15 hours, and the modified thermally conductive filler is filtered, washed, and dried.

7. The method for preparing a bio-based composite polyol for polyurethane adhesive according to claim 5, characterized in that: The preparation steps of the flame retardant biomass polyol are as follows: A1. 50 parts by mass of vegetable oil, 9 to 10 parts by mass of glycerol, and 37 to 38 parts by mass of a catalyst were mixed, heated to 140 to 200°C at 2 to 4°C / min, and stirred under vacuum at -0.096 MPa for 3 to 8 hours to obtain a mixture of vegetable oil monoglycerides and vegetable oil diglycerides; A2. Dissolve 30 parts by weight of a mixture of vegetable oil monoglycerides and vegetable oil diesters and 10-11 parts by weight of triethylamine in 260-270 parts by weight of dichloromethane. Then, add 20-22 parts by weight of 2-methylphenyl dichlorophosphate dropwise over 1 hour. The mixture is reacted at 58-62°C for 4-6 hours, filtered, and the filtrate is washed with deionized water at least three times. The organic layer is separated and the organic solvent is removed by rotary evaporation to obtain the vegetable oil phosphate. A3. 37 parts by mass of vegetable oil phosphate, 17-18 parts by mass of m-chloroperbenzoic acid, and 190-200 parts by mass of dichloromethane were mixed and reacted at 0°C for 2.5-3.5 hours. After the reaction, the crude product was filtered and distilled under vacuum to remove the dichloromethane; the crude product was then dissolved in ethyl acetate and washed with 5% sodium sulfite solution, 5% sodium carbonate solution, and deionized water, respectively. The organic phase was rotary evaporated to remove the solvent to obtain epoxidized vegetable oil phosphate; 50 parts by mass of epoxidized vegetable oil phosphate was purged with nitrogen for protection, heated to 85-95°C, and then 3-4 parts by mass of azobisisobutyronitrile was added, followed by 35-37 parts by mass of N-chlorosuccinimide. After the reaction was allowed to react for 2-4 hours, 42-44 parts by mass of tetrabutylammonium bromide was added, the temperature was raised to 125-135°C, and then 33-35 parts by mass of water was added. The mixture was kept at reflux for 3-4 hours to obtain a flame-retardant biomass polyol.

8. The method for preparing a bio-based composite polyol for a polyurethane adhesive according to claim 7, wherein: In step A1, the catalyst used is a basic catalyst.

9. The method for preparing a bio-based composite polyol for a polyurethane adhesive according to claim 7, wherein: The vegetable oils include soybean oil, castor oil, cashew nut shell oil, rapeseed oil and peanut oil.

10. The method for preparing bio-based composite polyol for polyurethane adhesive according to claim 5, characterized in that: When the bio-based composite polyol for polyurethane adhesive is used, the mass ratio of the bio-based composite polyol for polyurethane adhesive to the isocyanate monomer is 2.4-3:1.

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