High-temperature-resistant waterborne polyurethane and preparation method thereof

Abstract

The invention belongs to the technical field of waterborne polyurethane preparation, and particularly relates to high-temperature-resistant waterborne polyurethane and a preparation method thereof.The preparation method comprises the steps that polyester polyol and acetone are mixed, dimethylolpropionic acid is added, the temperature is increased to 70-80 DEG C, MDI, HDI and TDI are added, and a NCO-terminated polyurethane prepolymer is obtained through a reaction; cooling to 55 DEG C or below, adding triethylamine diluted by hydrochloric acid, uniformly mixing, adding water for emulsification, then adding a chain extender and a coupling agent which are diluted by water, refluxing with acetone, and reducing pressure to obtain high-temperature-resistant waterborne polyurethane; the prepared high-temperature-resistant waterborne polyurethane not only can be used for bonding high-performance fiber cloth such as aramid fibers, ultra-high molecular weight polyethylene and carbon fibers, but also has relatively high bonding strength, and the bonding strength is only reduced by 25% after the high-temperature-resistant waterborne polyurethane is placed at the high temperature of 155 DEG C for 3 hours and is superior to that of common polyurethane (reduced by 90%); the waterborne polyurethane prepared by the preparation method disclosed by the invention has a good high-temperature-resistant effect.

Description

Technical Field

[0001] The invention belongs to the technical field of waterborne polyurethane preparation, and in particular relates to high temperature resistant waterborne polyurethane and a preparation method thereof. Background Art

[0002] Waterborne polyurethane is a new type of polyurethane system that uses water instead of organic solvents as a dispersion medium. It is also called water-dispersible polyurethane, water-based polyurethane or water-based polyurethane. Waterborne polyurethane uses water as a solvent and has the advantages of being pollution-free, safe and reliable, having excellent mechanical properties, good compatibility, and easy to modify.

[0003] Waterborne polyurethane can be divided into anionic waterborne polyurethane, cationic waterborne polyurethane and nonionic waterborne polyurethane. Among them, the anionic type is the most important, which is divided into two categories: carboxylic acid type and sulfonic acid type.

[0004] ‌The performance changes of waterborne polyurethane in high temperature environment are crucial to its application‌. When the ambient temperature exceeds 80℃, some important properties of waterborne polyurethane, such as tensile strength and elastic modulus, will decrease to varying degrees. When the use temperature is above 200℃, polyurethane will inevitably undergo thermal decomposition, which limits its use under high temperature conditions. Therefore, improving the high temperature resistance of waterborne polyurethane is of great significance to expand its application range and enhance its use effect.

[0005] ‌The molecular structure and material formula of waterborne polyurethane are key factors in its high temperature resistance. The heat resistance of waterborne polyurethane mainly depends on the effects of its molecular structure and various components in the material formula. For example, factors such as the length of the molecular chain, the terminal functional group and the hard segment content will affect its thermal stability. In addition, different material processing methods and additives will also have a significant impact on heat resistance. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a high temperature resistant waterborne polyurethane and a preparation method thereof, so as to improve the high temperature resistance of the waterborne polyurethane.

[0007] The embodiment of the present invention provides a method for preparing a high temperature resistant waterborne polyurethane, comprising mixing polyester polyol and acetone, adding dimethylol propionic acid, heating to 70-80° C., and then adding MDI, HDI and TDI to react to obtain an NCO-terminated polyurethane prepolymer; The temperature was lowered to below 55°C, triethylamine diluted with hydrochloric acid was added, and after uniform mixing, water was added for emulsification, and then a chain extender and a coupling agent diluted with water were added. After acetone refluxed, the pressure was reduced to obtain a high temperature resistant waterborne polyurethane.

[0008] Preferably, the polyester polyol is first subjected to vacuum dehydration at 130° C. for 2-4 hours before being mixed with acetone.

[0009] Preferably, the weight ratio of the polyester polyol to acetone is 5-7:8-15.

[0010] Preferably, the weight ratio of the polyester polyol to dimethylol propionic acid is 5-7:0.6-1.

[0011] Preferably, the weight ratio of the polyester polyol to the total weight of MDI, HDI and TDI is 5-8:2-4.

[0012] Preferably, the molar ratio of MDI, HDI and TDI is 1:1:4.

[0013] Preferably, in the triethylamine diluted with hydrochloric acid, the mass concentration of hydrochloric acid is 3-5%, and the weight ratio of hydrochloric acid to triethylamine is 8-10:1.

[0014] Preferably, the chain extender is ethylenediamine or isophoronediamine.

[0015] Preferably, the coupling agent is NB-(aminoethyl)-Y-aminopropyldimethoxysilane.

[0016] The embodiment of the present invention provides a high temperature resistant waterborne polyurethane, which is prepared by adopting the preparation method.

[0017] The beneficial effect of the present invention is that the present invention mixes polyether polyol and acetone, adds DMPA, and also adds a mixture of three cyanate esters, namely HDI, MDI and TDI, and the prepared high-temperature resistant water-based polyurethane can not only bond high-performance fiber cloths such as aramid, ultra-high molecular weight polyethylene and carbon fiber, but also has high bonding strength. Moreover, after being placed at a high temperature of 155°C for 3 hours, the bonding strength is tested to only decrease by 25%, which is better than ordinary polyurethane (decreased by 90%). The water-based polyurethane prepared by the present invention has good high-temperature resistance. DETAILED DESCRIPTION

[0018] Example 1 A method for preparing high temperature resistant waterborne polyurethane comprises the following steps: The polyester polyol was dehydrated at 130°C in vacuum for 3 h.

[0019] In a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, 60 g of vacuum-dehydrated polyether polyol and 100 g of acetone were added, and 8 g of dimethylol propionic acid (DMPA) was added under stirring. After heating to 75°C, 4,4'-diphenylmethane diisocyanate (MDI), 1,6-ethylene diisocyanate (HDI), and toluene diisocyanate (TDI) (molar ratio HDI:MDI:TDI=1:1:4) were added. The total weight of MDI, HDI and TDI was 30 g. After reacting for 5 hours, an NCO-terminated polyurethane prepolymer was obtained.

[0020] Then cool down, when the temperature drops to 50°C, add 30g of triethylamine diluted with dilute hydrochloric acid (the mass concentration of dilute hydrochloric acid is 3%, and the weight ratio of hydrochloric acid to triethylamine is 10:1), stir for 30 minutes, then add 200g of distilled water and emulsify under strong stirring, and add 40g of ethylenediamine diluted with water (the weight ratio of water to ethylenediamine is 5:1), 5g of NB-(aminoethyl)-Y-aminopropyldimethoxysilane, chain extension, stir for 50 minutes, reflux acetone for 1 hour, remove acetone under reduced pressure, and obtain high temperature resistant water-based polyurethane.

[0021] The high temperature resistant waterborne polyurethane prepared in Example 1 can not only bond high-performance fiber fabrics such as aramid, ultra-high molecular weight polyethylene and carbon fiber, but also has high bonding strength. Moreover, after being placed at a high temperature of 155°C for 3 hours, the bonding strength only decreases by 25%, which is better than ordinary polyurethane (decreased by 90%). The waterborne polyurethane prepared in the present invention has good high temperature resistance.

[0022] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0023] One or more embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a high temperature resistant waterborne polyurethane, characterized in that: Mix polyester polyol and acetone, add dimethylol propionic acid, raise the temperature to 70-80°C, then add MDI, HDI and TDI to react to obtain NCO-terminated polyurethane prepolymer; The temperature was lowered to below 55°C, triethylamine diluted with hydrochloric acid was added, and after uniform mixing, water was added for emulsification, and then a chain extender and a coupling agent diluted with water were added. After acetone refluxed, the pressure was reduced to obtain a high temperature resistant waterborne polyurethane.

2. The preparation method according to claim 1, characterized in that: Before mixing with acetone, the polyester polyol was first subjected to vacuum dehydration at 130°C for 2-4h.

3. The preparation method according to claim 1, characterized in that: The weight ratio of the polyester polyol to acetone is 5-7:8-15.

4. The preparation method according to claim 1, characterized in that: The weight ratio of the polyester polyol to dimethylol propionic acid is 5-7: 0.6-1。 5. The preparation method according to claim 1, characterized in that: The weight ratio of the polyester polyol to the total weight of MDI, HDI and TDI is 5-8:2-4.

6. The preparation method according to claim 1, characterized in that: The molar ratio of the MDI, HDI and TDI is 1:1:

4.

7. The preparation method according to claim 1, characterized in that: In the triethylamine diluted with hydrochloric acid, the mass concentration of hydrochloric acid is 3-5%, and the weight ratio of hydrochloric acid to triethylamine is 8-10:

1.

8. The preparation method according to claim 1, characterized in that: The chain extender is ethylenediamine or isophoronediamine.

9. The preparation method according to claim 1, characterized in that: The coupling agent is NB-(aminoethyl)-Y-aminopropyldimethoxysilane.

10. A high temperature resistant waterborne polyurethane, characterized in that: The preparation is obtained by the preparation method according to any one of claims 1 to 9.