Nano-composite thermoplastic polyurethane adhesive material and preparation method thereof

Abstract

The invention discloses a nano composite thermoplastic polyurethane adhesive material and a preparation method thereof. The preparation method comprises the following steps: digesting a commercial GaAlSi2O5 (OH) 4 nanotube in alkoxylated polyol, so as to prepare a modified nanotube; the preparation method comprises the following steps: mixing a commercial diisocyanate tripolymer with commercial polyisocyanate, and adding a silane coupling agent to prepare modified polyisocyanate; mixing modified polyisocyanate and polyol, dropwise adding n-butyltin dilaurate in a nitrogen environment to obtain a polyurethane prepolymer, mixing the polyurethane prepolymer with the modified nanotube to obtain a modified polyurethane prepolymer, adding the modified polyurethane prepolymer into a revolution and rotation stirring defoaming machine, adding an ethylene glycol chain extender, stirring, defoaming, preparing the adhesive into a film by using a casting machine, and drying, thereby obtaining the high-strength polyurethane adhesive. And curing to obtain the nano composite thermoplastic polyurethane adhesive. According to the invention, the GaAlSi2O5 (OH) 4 nanotube is adopted to modify the polyurethane microstructure, so that the weather resistance, light degradation resistance and adhesion of the polyurethane material are enhanced on the premise of not losing the optical performance.

Description

Technical Field

[0001] The invention relates to the technical field of advanced transparent polymer material preparation, and in particular to a nano composite thermoplastic polyurethane adhesive material and a preparation method thereof. Background Art

[0002] At present, most of the transparent armor in service is made of multi-layer transparent glass composites, which use thermoplastic polyurethane adhesive as a composite material. However, since polyurethane adhesive is a long-chain polymer formed by the polymerization of isocyanate (monomer) and hydroxyl compounds, it contains polar groups such as amino groups (NHCOO), isocyanate groups (NCO), urea groups, etc., which makes it very easy to bulge, crack, and reduce bonding strength in summer. In addition, thermoplastic polyurethane adhesives are brittle at low temperatures at minus 35°C, which reduces their bonding performance.

[0003] In order to improve the bonding performance of thermoplastic polyurethane adhesives, some scholars have modified polyurethane materials by internal cross-linking modification, external cross-linking modification, mechanical blending modification and chemical modification. However, although these modification methods can achieve good bonding, there is no clear report on the low temperature performance, light transmittance and weather resistance of the modified colloid. Chinese patent application CN117601463A discloses a method for preparing a polyurethane composite material, which uses continuous fiber woven fabric as a reinforcing material to improve the mechanical properties of the polyurethane composite material. However, this type of toughened polyurethane composite material can only be used as a profile and does not have optical properties. Chinese patent application CN117656637A discloses a highly light-resistant polyurethane composite material, a preparation method and an application thereof, which adopts a compounding scheme of adding anti-yellowing additives, anti-ultraviolet agents and antioxidants to improve the durability and light degradation resistance of the polyurethane material. However, the polyurethane product is used as an automobile interior and does not have the ability to transmit light. Therefore, it is of great significance to study how to enhance the weather resistance, light degradation resistance and adhesion of the polyurethane material without losing the optical properties of the thermoplastic polyurethane. Summary of the invention

[0004] The purpose of the present invention is to obtain a nano-composite thermoplastic polyurethane adhesive material and a preparation method thereof, and GaAlSi2O5(OH)4 nanotubes are used to modify the polyurethane microstructure. Without losing the optical properties, the problems of easy aging, yellowing, low-temperature brittle failure and the like of the polyurethane adhesive are solved, and the bonding strength, weather resistance, anti-ballistic performance and other protective parameters of the polyurethane adhesive are improved, and the synthesis process of the polyurethane adhesive is simplified, thereby improving the yield rate of the polyurethane adhesive.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] In one aspect, the present invention provides a nanocomposite thermoplastic polyurethane adhesive material, the method specifically comprising the following steps:

[0007] (1) Nanotube modification: commercial GaAlSi2O5(OH)4 nanotubes are digested in alkoxylated polyols using an ultrasonic digester, wherein the molar ratio of GaAlSi2O5(OH)4 nanotubes to alkoxylated polyols is 1:3 to 1:5, to obtain modified GaAlSi2O5(OH)4 nanotubes;

[0008] (2) Polyisocyanate modification: commercial diisocyanate trimer and commercial polyisocyanate are mixed in a mass ratio of 50:50 to prepare a polyisocyanate mixture, and a silane coupling agent is added in an amount of 1 to 3 wt % of the mass of the polyisocyanate mixture. The mixture is modified at 40 to 60° C. to obtain a modified polyisocyanate;

[0009] (3) Synthesis of polyurethane prepolymer: The polyisocyanate obtained in step (2) is mixed with a polyol, stirred at 40-50° C., at a stirring speed of 200-300 r / min, high-purity nitrogen is introduced, stirring is continued for 15-30 min, 0.05-0.1 wt % of n-butyltin dilaurate is added dropwise, the temperature is increased to 60-70° C., the stirring speed is 300-400 r / min, and the reaction is carried out for 60-90 min to obtain a polyurethane prepolymer;

[0010] (4) polyurethane prepolymer modification: adding the modified nanotubes obtained in step (1) to the polyurethane prepolymer obtained in step (3), raising the reaction temperature to 75-85° C., maintaining the stirring speed at 100-150 r / min, and reacting for 90-180 min to obtain a modified polyurethane prepolymer;

[0011] (5) Synthesis of thermoplastic polyurethane adhesive: Add the polyurethane prepolymer obtained in step (4) into a rotary stirring defoamer, add 0.5-3.0wt% ethylene glycol chain extender based on the mass of the polyurethane prepolymer, adjust the temperature of the defoamer to 30-40°C, the rotation speed to 1500-2500r / min, and defoam for 60-90min; adjust the temperature to 50-60°C, the rotation speed to 1500-2500r / min, and defoam for 15-30min; use a casting machine to make the obtained adhesive into a film, maintain the temperature at 75-85°C for curing, and after curing, a finished nano-composite thermoplastic polyurethane adhesive can be obtained.

[0012] Preferably, in step (1), the alkoxylated polyol is a difunctional type, the ultrasonic digestion temperature is 40 to 50° C., and the digestion time is 60 to 120 min.

[0013] Preferably, in step (4), the amount of modified nanotubes added is 0.4 to 1.2 wt % of the mass of the polyurethane prepolymer.

[0014] On the other hand, the present invention provides a nano-composite thermoplastic polyurethane adhesive material prepared by the above preparation method.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. A nano-composite thermoplastic polyurethane adhesive material and a preparation method thereof disclosed in the present invention are firstly to uniformly disperse nanotubes in alkoxylated polyols by means of the cavitation effect of ultrasonic high-frequency vibration, and to make active groups such as hydroxyl (-OH) combine with active sites on the surface of nanotubes by means of physical adsorption and chemical adsorption between nanotubes and alkoxylated polyols, so as to achieve modification of nanotubes. By means of the polymerization reaction between diisocyanate trimer and polyisocyanate, the crosslinking density of polyisocyanate is increased, and the isocyanate groups in polyisocyanate are reacted and bridged with modified nanotubes by means of silane coupling agent, so as to improve the efficiency of addition reaction between polyisocyanate and polyols, and oxygen is removed in the reaction by means of high-purity nitrogen, so as to avoid the occurrence of side reactions such as oxidation reaction. The active groups on the surface of modified nanotubes (active groups obtained by modification in alkoxylated polyols) can undergo activation reaction with active groups such as isocyanate groups or hydroxyl groups in polyurethane prepolymers. This activation reaction allows the nanotubes to be evenly dispersed in the polyurethane prepolymer and combined with the polyurethane prepolymer by chemical bonding, thereby changing the physical and chemical properties of the polyurethane prepolymer to obtain a nanocomposite polyurethane. Finally, by adding an ethylene glycol chain extender, the hydroxyl groups in the ethylene glycol chain extender can continue to react with the isocyanate groups in the polyurethane prepolymer to further grow the molecular chain, thereby adjusting the molecular weight and performance of the polyurethane to obtain an adhesive material.

[0017] 2. A nanocomposite thermoplastic polyurethane adhesive material and a preparation method thereof disclosed in the present invention are directly prepared by a one-step reaction method. The preparation process is energy-saving and environmentally friendly, no toxic gas, no additional by-products are generated, the reaction rate is controllable, and it is suitable for large-scale mass production;

[0018] 3. The present invention discloses a nanocomposite thermoplastic polyurethane adhesive material and a preparation method thereof. The core of the invention is to use GaAlSi2O5(OH)4 nanotubes for structural modification. The pseudo-hexagonal symmetry of the nanotubes collapses during the digestion process, so that more silicon-hydroxyl groups are exposed on the surface of the GaAlSi2O5(OH)4 nanotubes, thereby enhancing the reaction probability and reaction activity of the nanotubes with the polyurethane prepolymer, thereby achieving the modification of the polyurethane microstructure and improving the weather resistance and bonding strength of the polyurethane material.

[0019] 4. The present invention discloses a nano-composite thermoplastic polyurethane adhesive material and a preparation method thereof, which is a composite modification without losing the optical properties of the polyurethane itself. The prepared polyurethane adhesive has a haze of <0.5 and a transmittance of >85%. It can be directly used for the bonding of transparent parts such as multi-layer transparent glass, protective armor, and protective masks, solving the problems of yellowing and failure of traditional layer adhesive materials. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific embodiments.

[0021] Example 1

[0022] (1) Nanotube modification: Commercial GaAlSi2O5(OH)4 nanotubes were digested in alkoxylated polyols using an ultrasonic digester, the molar ratio of GaAlSi2O5(OH)4 nanotubes to alkoxylated polyols was 1:3, the ultrasonic digestion temperature was 45°C, the digestion time was 90 min, and modified GaAlSi2O5(OH)4 nanotubes were obtained;

[0023] (2) Polyisocyanate modification: commercial diisocyanate trimer and commercial polyisocyanate were mixed in a mass ratio of 50:50 to prepare a polyisocyanate mixture, and a silane coupling agent was added. The amount of the silane coupling agent added was 1.5 wt % of the mass of the polyisocyanate mixture. The reaction temperature was 50° C. to obtain a modified polyisocyanate.

[0024] (3) Synthesis of polyurethane prepolymer: The polyisocyanate obtained in step (2) was mixed with the polyol, stirred at 45° C. and a stirring speed of 250 r / min, high-purity nitrogen was introduced, stirring was continued for 20 min, 0.08 wt % of n-butyltin dilaurate was dropped, the temperature was increased to 65° C., the stirring speed was 350 r / min, and the reaction was carried out for 60 min to obtain a polyurethane prepolymer;

[0025] (4) polyurethane prepolymer modification: adding the modified nanotubes obtained in step (1) to the polyurethane prepolymer obtained in step (3), wherein the amount of pure nanotubes added is 0.8 wt% of the mass of the polyurethane prepolymer, raising the reaction temperature to 80° C., maintaining the stirring speed at 130 r / min, and reacting for 150 min to obtain a modified polyurethane prepolymer;

[0026] (5) Synthesis of thermoplastic polyurethane adhesive: The polyurethane prepolymer obtained in step (4) is added to a rotary stirring defoamer, and 1.0 wt% of ethylene glycol chain extender is added based on the mass of the prepolymer. The temperature of the defoamer is adjusted to 35°C, the rotation speed is 2000 r / min, and the defoaming is performed for 60 min; the temperature is adjusted to 55°C, the rotation speed is 2000 r / min, and the defoaming is performed for 20 min; the obtained adhesive is made into a film using a casting machine, and the temperature is maintained at 80°C for curing. After the curing is completed, a finished nano-composite thermoplastic polyurethane adhesive is obtained.

[0027] Example 2

[0028] (1) Nanotube modification: Commercial GaAlSi2O5(OH)4 nanotubes were digested in alkoxylated polyols using an ultrasonic digester, the molar ratio of GaAlSi2O5(OH)4 nanotubes to alkoxylated polyols was 1:5, the ultrasonic digestion temperature was 50°C, the digestion time was 60 min, and modified GaAlSi2O5(OH)4 nanotubes were obtained;

[0029] (2) Polyisocyanate modification: commercial diisocyanate trimer and commercial polyisocyanate were mixed in a weight ratio of 50:50 to prepare a polyisocyanate mixture, and a silane coupling agent was added. The amount of the silane coupling agent added was 3.0 wt% of the weight of the polyisocyanate mixture. The reaction temperature was 60° C. to obtain a modified polyisocyanate.

[0030] (3) Synthesis of polyurethane prepolymer: The polyisocyanate obtained in step (2) was mixed with the polyol, stirred at 50° C. and 300 r / min, high-purity nitrogen was introduced, stirring was continued for 30 min, 0.1 wt % of n-butyltin dilaurate was dropped, the temperature was raised to 70° C., the stirring speed was 300 r / min, and the reaction was carried out for 90 min to obtain a polyurethane prepolymer;

[0031] (4) Modification of polyurethane prepolymer: adding the modified nanotubes obtained in step (1) to the polyurethane prepolymer obtained in step (3), wherein the amount of pure nanotubes added is 1.2 wt% of the mass of the polyurethane prepolymer, raising the reaction temperature to 85° C., maintaining the stirring speed at 150 r / min, and reacting for 180 min to obtain a modified polyurethane prepolymer;

[0032] (5) Synthesis of thermoplastic polyurethane adhesive: Add the polyurethane prepolymer obtained in step (4) into a rotary stirring defoamer, add 3.0 wt% of ethylene glycol chain extender based on the mass of the prepolymer, adjust the temperature of the defoamer to 40°C, the rotation speed to 1500 r / min, and defoam for 90 min; adjust the temperature to 60°C, the rotation speed to 2500 r / min, and defoam for 30 min; use a casting machine to make the obtained adhesive into a film, maintain the temperature at 80°C for curing, and after curing, obtain a finished nano-composite thermoplastic polyurethane adhesive.

[0033] Table 1 Example 1 Sample test data

[0034] project index Test Standards Tensile Strength ≥45MPa GB / T528-2009 Elongation at break ≥450％ GB / T528-2009 Tear strength ≥43kN / m GB / T529-2009 Bonding strength with electrodeless glass ≥29kN / m GJB 446-1988 Indentation hardness 75IRHD~85IRHD GBT531.1-2008 Glass transition temperature ≤-68℃ GB / T19466.2-2004 Light transmittance ≥90％ GB / T2410-2008 Haze ≤0.3％ GB / T2410-2008

[0035] Table 2 Example 2 Sample Test Data

[0036]

[0037]

[0038] It can be seen from the experimental data in Table 1 and Table 2 that the nanocomposite thermoplastic polyurethane adhesive prepared by modifying the polyurethane microstructure with GaAlSi2O5(OH)4 nanotubes has a transmittance greater than 90%, a haze less than 0.3%, a tensile strength greater than 42MPa, an elongation at break greater than 450%, a tear strength greater than 40kN / m, a bonding strength with electrodeless glass greater than 25kN / m, and a glass transition temperature less than -68°C, thereby achieving enhanced weather resistance, light degradation resistance and adhesion of polyurethane materials without losing optical properties.

[0039] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a nanocomposite thermoplastic polyurethane adhesive material, characterized in that: The method specifically comprises the following steps: (1) Nanotube modification: commercial GaAlSi2O5(OH)4 nanotubes are digested in alkoxylated polyols using an ultrasonic digester, wherein the molar ratio of GaAlSi2O5(OH)4 nanotubes to alkoxylated polyols is 1:3 to 1:5, to obtain modified GaAlSi2O5(OH)4 nanotubes; (2) Polyisocyanate modification: commercial diisocyanate trimer and commercial polyisocyanate are mixed in a mass ratio of 50:50 to prepare a polyisocyanate mixture, and a silane coupling agent is added in an amount of 1 to 3 wt % of the mass of the polyisocyanate mixture. The mixture is modified at 40 to 60° C. to obtain a modified polyisocyanate; (3) Synthesis of polyurethane prepolymer: The polyisocyanate obtained in step (2) is mixed with a polyol, stirred at 40-50° C., at a stirring speed of 200-300 r / min, high-purity nitrogen is introduced, stirring is continued for 15-30 min, 0.05-0.1 wt % of n-butyltin dilaurate is added dropwise, the temperature is increased to 60-70° C., the stirring speed is 300-400 r / min, and the reaction is carried out for 60-90 min to obtain a polyurethane prepolymer; (4) polyurethane prepolymer modification: adding the modified nanotubes obtained in step (1) to the polyurethane prepolymer obtained in step (3), raising the reaction temperature to 75-85° C., maintaining the stirring speed at 100-150 r / min, and reacting for 90-180 min to obtain a modified polyurethane prepolymer; (5) Synthesis of thermoplastic polyurethane adhesive: Add the polyurethane prepolymer obtained in step (4) into a rotary stirring defoamer, add 0.5-3.0wt% ethylene glycol chain extender based on the mass of the polyurethane prepolymer, adjust the temperature of the defoamer to 30-40°C, the rotation speed to 1500-2500r / min, and defoam for 60-90min; adjust the temperature to 50-60°C, the rotation speed to 1500-2500r / min, and defoam for 15-30min; use a casting machine to make the obtained adhesive into a film, maintain the temperature at 75-85°C for curing, and after curing, obtain a finished nano-composite thermoplastic polyurethane adhesive.

2. The method for preparing a nanocomposite thermoplastic polyurethane adhesive material according to claim 1, characterized in that: In step (1), the alkoxylated polyol is a difunctional type, the ultrasonic digestion temperature is 40-50° C., and the digestion time is 60-120 min.

3. The method for preparing a nanocomposite thermoplastic polyurethane adhesive material according to claim 1, characterized in that: In step (4), the amount of modified nanotubes added is 0.4 to 1.2 wt % of the mass of the polyurethane prepolymer.

4. A nanocomposite thermoplastic polyurethane adhesive material, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 3.

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