CN110734533A

CN110734533A - terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion and preparation method thereof

Info

Publication number: CN110734533A
Application number: CN201910958179.4A
Authority: CN
Inventors: 许伟; 赵维甲; 王文; 郝丽芬; 刘红呐; 王学川
Original assignee: Shaanxi University of Science and Technology
Current assignee: Shaanxi University of Science and Technology
Priority date: 2019-10-10
Filing date: 2019-10-10
Publication date: 2020-01-31

Abstract

The invention relates to a preparation method of terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion, which comprises the steps of firstly, taking diethanol amine and a fluorine-containing acrylate monomer as raw materials, taking absolute ethyl alcohol as a solvent to prepare a micromolecule fluorine-containing chain extender, then taking gamma-aminopropyltriethoxysilane and a hydroxyethyl acrylate monomer as raw materials, and taking 4-methoxyphenol as a polymerization inhibitor to prepare the micromolecule silicon-containing chain extender; isophorone diisocyanate and polyester or polyether diol are used as raw materials, dibutyltin dilaurate is used as a catalyst, and 2, 2-dimethylolpropionic acid, 1, 4-butanediol, a micromolecule fluorine-containing chain extender and a micromolecule silicon-containing chain extender are added to prepare a side chain fluoroalkyl/siloxy co-modified polyurethane prepolymer; dropwise adding organic fluorine alcohol to prepare fluoroalkyl single-side end-capped polyurethane, and respectively dropwise adding a cross-linking agent and solvent type silica sol to prepare terminal fluoroalkyl and side chain fluoroalkyl co-modified polyurethane nano hybrid materials; and finally, triethylamine and water are added to prepare the terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion.

Description

terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion and preparation method thereof

Technical Field

The invention relates to the field of polyurethane coatings, in particular to a preparation method of terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion.

Background

The waterborne polyurethane is novel polyurethane using water to replace an organic solvent as a dispersion medium, can greatly reduce the harm of the organic solvent to the ecological environment, is widely applied to the fields of leather finishing agents, adhesives, medical instruments, aerospace, fabric finishing and the like by due to the advantages of no pollution, no toxicity, low cost, easiness in modification and the like, but has the defects of poor water resistance, poor weather resistance, no high temperature resistance and the like.

The fluorine and silicon co-modified waterborne polyurethane has been reported in related documents, for example, the introduction of fluorosilicone oil modified waterborne polyurethane: SU first uses hydroxyl fluorine silicone oil (PTFPMS)

Synthesizing hard segment monomer with isophorone diisocyanate, and reacting with diisocyanate, polyester diol, chain extender, etc. to obtain kinds of fluorine and silicon co-modified polyurethane (European Polymer journal,2010,46(3): 472-483).]. Synthesis of amino-terminated fluorosilicone oil from Baonayu

As a soft segment chain extender, and then reacts with diisocyanate and polyether glycol to prepare the hydroxyl fluorine silicone oil modified polyether polyurethane (chemical building material, 2007, (03): 17-19).]. According to the two schemes, the fluoroalkyl and the siloxy are embedded in the main chain of polyurethane, the structure is not beneficial to the directional migration of the fluorine-silicon chain segment to the surface during film forming, the fluorine-silicon group is not spread compactly on the surface of the coating, and the hydrophobicity is difficult to guarantee. And the introduction of the fluorosilicone oil leads the hydrophilicity of the polyurethane to be poor, so that the emulsification is difficult, and the stability of the emulsion is reduced. Researchers have also synergistically modified waterborne polyurethanes with polydimethoxysilanes and fluorine-containing diols: DU adopts a step-by-step polymerization method to react the polydimethoxysilane and the fluorinated ether polyol which are taken as soft segments with diisocyanate and polyether glycol to prepare polyurethane prepolymer

Then the fluorine and silicon co-modified aqueous polyurethane emulsion [ Macromolecular resin ] is prepared by chain extension, neutralization and emulsificationch,2015,23(9):867-875.]Senthilkumar utilizes polydimethoxysilane, a fluorine-containing polyol and soy polyol in different proportions as soft segments to synthesize series aqueous polyurethane emulsions, and the study results show that the amount of the fluorine-containing polyol on the surface is not clearly related to the hydrophobicity of the coating [ Journal of Applied Polymer Science,2013,130(6): 3874-.]The two schemes can ensure good emulsion stability, but the fluorine-silicon chain segment is still only embedded in the main chain of polyurethane, the coating hydrophobicity is difficult to reach the expectation, and the fluorine-containing dihydric alcohol has less varieties and high price, so that the preparation cost is multiplied, and the method is difficult to be applied to practical production]. Panjirong also adopts emulsion polymerization method to synthesize organosilicon modified aqueous polyurethane emulsion by diisocyanate, polypropylene glycol, hydroxyl terminated siloxane and chain extender as the shell layer of the composite emulsion, and then adds core layer monomers such as fluorine-containing acrylate to obtain the fluorine-silicon modified polyurethane-polyacrylate composite emulsion. [ science and engineering of Polymer materials, 2012,28(08):1-4.]. In the two schemes, the fluoroalkyl groups are positioned on two sides of the polyurethane main chain, but the siloxane is anchored on the polyurethane main chain, so that the surface migration is limited, and the hydrophobicity cannot be obviously improved. Under the condition of higher concentration of acrylic monomer, the fluorine-containing acrylate is not easy to enter micelles to generate polymerization reaction, so that the actual fluorine content of the product is less than the theoretical value, and the system stability is reduced by using too high amount of the fluorine-containing acrylate. While fluoroalkyl groups at the end of the polymer chain migrate more readily to the surface and are more effective in hydrophobic interactions. Therefore, there are documents in which a fluoroalkyl-terminated modified polyurethane [ acsappl. mater. inter.2015,7: 13538-; RSC adv, 2015,5: 79807-.]. However, after the film is formed, the spreading of the fluorine-containing group on the film surface is not compact enough, and the shielding protection effect on the whole polymer substrate is insufficient, so that the materialThe properties of water resistance, stain resistance, abrasion resistance, durability, etc. are difficult to achieve the intended targets.

In conclusion, how to effectively utilize the fluorine and silicon modified polyurethane emulsion to improve the hydrophobicity and the comprehensive application performance and save the cost has important significance.

Disclosure of Invention

The invention aims to provide a preparation method of terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsions, which can effectively reduce the dosage of fluorine-containing monomers, reduce the preparation cost and enhance the mechanical properties of a coating under the premise of further hydrophobic property improvement.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: we do so here, to the completion of the claims.

Compared with the prior art, the invention has the following advantages:

according to the invention, steps are carried out to improve the water resistance of the aqueous polyurethane emulsion, terminal fluoroalkyl, side chain fluoroalkyl and siloxy are used for carrying out synergistic modification on polyurethane, the migration of fluorine-containing and silicon-containing groups to the surface in the film forming process can be promoted, and the fluorine-containing and silicon-containing groups can also be densely spread on the surface of a coating, so that the shielding protection of a polyurethane film is improved.

Drawings

FIG. 1 is a photograph (131.3 degree) of the water contact angle of the terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion prepared in example 1 after film formation;

FIG. 2 is a photograph (129.4 degree) of the water contact angle of the terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion prepared in example 2 after forming a film;

FIG. 3 is a photograph (129.0 degree) of the water contact angle of the hybrid emulsion of terminal/side fluoroalkyl co-modified polyurethane nano-emulsion prepared in example 3 after film formation.

FIG. 4 is a graph showing the relationship between 50% mass loss and temperature before and after modification in accordance with the present invention, in which PU is unmodified polyurethane, HBFPUF is polyurethane modified with only organic fluorine, and HBSiFPUF is polyurethane co-modified with fluorine and silicon

Detailed Description

The invention relates to a preparation method of terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion, which comprises the following steps:

the reaction equation for synthesizing the micromolecular fluorine-containing chain extender (DEFA) in the step (1) is as follows:

the reaction equation for synthesizing the micromolecular silicon-containing chain extender (DESIA) in the step (2) is as follows:

the reaction equation for synthesizing the terminal/side fluoroalkyl group co-modified polyurethane nano hybrid emulsion (HBSiFPUF) in the steps (3) to (5) is as follows:

the invention is further illustrated with reference to specific examples.

The reagents in the examples were dried before use, and the relative molecular mass of polycaprolactone diol used was 1000, and the relative molecular mass of polytetrahydrofuran diol was 1000. The dibutyltin dilaurate used is used as a catalyst, and the 4-methoxyphenol is used as a polymerization inhibitor.

Example 1:

terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion is prepared by the following preparation method, which sequentially comprises the following steps:

1) accurately weighing 10.51g (0.1mol) of Diethanolamine (DEOA) and 25g (0.1mol) of hexafluorobutyl methacrylate, adding into a 250ml three-neck flask, adding 80g of absolute ethyl alcohol as a solvent, stirring and reacting for 8 hours under the conditions of condensation reflux at the temperature of 60 ℃, removing the solvent by rotary evaporation under the conditions of 50 ℃ and-0.1 MPa after the reaction is finished, and obtaining the micromolecular fluorine-containing chain extender (DEFA) for later use.

2) Accurately weighing 22.1g (0.1mol) of gamma-aminopropyltriethoxysilane and 0.062g (0.0005mol) of 4-methoxyphenol, adding into another three-neck flasks of 250ml, slowly dropwise adding 23.2g (0.2mol) of hydroxyethyl acrylate under the ice bath condition, then putting the flasks into an oil bath kettle, and stirring and reacting for 6 hours under the condensation reflux condition at 40 ℃ to obtain the micromolecule silicon-containing chain extender (DESIA) for later use.

3) Accurately weighed 11.11g (0.05mol) isophorone diisocyanate (IPDI) and 18.52g polycaprolactone diol (PCL1000), added into another three-neck flask, heated in oil bath, and placed in a N₂Heating and stirring under the protection condition, adding three drops of dibutyltin dilaurate (DBTDL) when the temperature of a system reaches 80 ℃, continuously reacting for 1h, sequentially adding 2.14g of 2, 2-dimethylolpropionic acid (DMPA), 0.36g of 1, 4-Butanediol (BDO), 2.01g of DEFA and 1.35g of DESIA for chain extension reaction, simultaneously adding 10ml of acetone to reduce the viscosity of the system, introducing condensed water, and continuously reacting for 2.5h to obtain the side chain fluoroalkyl and siloxy co-modified polyurethane prepolymer.

4) Weighing 4.20g of perfluoroethyloctanol under the condition of 80 ℃, uniformly mixing with 8ml of acetone, dropwise adding the mixture into a reaction system within 2h, continuously heating and stirring for 1h, then weighing 0.52g of Trimethylolpropane (TMP), dissolving with 10ml of acetone, dropwise adding the mixture into the reaction system within 0.5h, continuously heating and stirring for 0.5h, adding 7.0g of solvent type silica sol (acetone type) with 30% of solid content, reacting for 1h, cooling to 40 ℃, adding 1.62g of Triethylamine (TEA) for neutralization, reacting for 0.5h, finally weighing 93g of deionized water, dropwise adding the deionized water while stirring for emulsification, rotatably steaming the prepared emulsion at 50 ℃ and under 0.1MPa for 0.5h, removing the organic solvent, finally preparing the end/side fluoroalkyl co-modified polyurethane nano hybrid emulsion, spreading the emulsion in a polytetrafluoroethylene plate for natural drying to prepare a polyurethane adhesive film, and drying in an oven at 50 ℃ for 24h after weeks.

Example 2:

1) accurately weighing 10.51g (0.1mol) of Diethanolamine (DEOA) and 16.8g (0.1mol) of trifluoroethyl methacrylate, adding the weighed materials into a 250ml three-neck flask, adding 80g of absolute ethyl alcohol as a solvent, stirring and reacting for 8 hours under the conditions of 60 ℃ and condensation reflux, and performing rotary evaporation at 50 ℃ and-0.1 MPa to remove the solvent after the reaction is finished to obtain the micromolecular fluorine-containing chain extender (DEFA) for later use.

2) Accurately weighing 22.1g (0.1mol) of gamma-aminopropyltriethoxysilane and 0.062g (0.0005mol) of 4-methoxyphenol, adding into another three-neck flasks, slowly dropwise adding 23.2g (0.2mol) of hydroxyethyl acrylate under the ice bath condition, then putting the flasks into an oil bath kettle, and stirring and reacting for 6 hours under the condensation reflux condition at 40 ℃ to obtain the micromolecule silicon-containing chain extender (DESIA) for later use.

3) 11.11g (0.05mol) of isophorone diisocyanate (IPDI) and 19.23g of polytetrahydrofuran diol (PTMA1000) were weighed out accurately and introduced into a further 250ml three-neck flask, heated in an oil bath and placed under N₂Heating and stirring under the protection condition, adding three drops of dibutyltin dilaurate (DBTDL) when the temperature of a system reaches 80 ℃, continuously reacting for 1h, sequentially adding 2.06g of 2, 2-dimethylolpropionic acid (DMPA), 0.35g of 1, 4-Butanediol (BDO), 1.64g of DEFA and 1.04g of DESIA for chain extension reaction, simultaneously adding 10ml of acetone to reduce the viscosity of the system, introducing condensed water, and continuously reacting for 2.5h to obtain the side chain fluoroalkyl and siloxy co-modified polyurethane prepolymer.

4) Weighing 4.75g of perfluorohexylethanol at the temperature of 80 ℃, uniformly mixing with 8ml of acetone, dropwise adding into a reaction system within 2h, continuously heating and stirring for 1h, then weighing 0.57g of Triethanolamine (TEOA), dissolving with 10ml of acetone, dropwise adding into the reaction system within 0.5h, continuously heating and stirring for 0.5h, adding 7.0g of solvent type silica sol (acetone type) with the solid content of 30% for reacting for 1h, cooling to 40 ℃, adding 1.60g of Triethylamine (TEA) for neutralization, reacting for 0.5h, finally weighing 93g of deionized water, dropwise adding for emulsification while stirring, rotatably steaming the prepared emulsion at the temperature of 50 ℃ and the pressure of 0.1MPa for 0.5h, removing the organic solvent, finally preparing the end/side fluoroalkyl co-modified polyurethane nano hybrid emulsion, spreading 30g of the emulsion in a polytetrafluoroethylene plate, naturally drying to prepare a polyurethane adhesive film, and drying in an oven at the temperature of 50 ℃ for 24h after weeks.

Example 3:

3) Accurately weighed 11.11g (0.05mol) isophorone diisocyanate (IPDI) and 18.52g polycaprolactone diol (PCL1000), added to another three-necked flasks, heated in an oil bath, and placed in a N-bath₂Heating and stirring under the protection condition, adding three drops of dibutyltin dilaurate (DBTDL) when the temperature of the system reaches 80 ℃, continuously reacting for 1h, sequentially adding 2.14g of 2, 2-dimethylolpropionic acid (DMPA), 0.36g of 1, 4-Butanediol (BDO), 1.01g of DEFA and 2.02g of DESIA for chain extension reaction, simultaneously adding 10ml of acetone to reduce the viscosity of the system, introducing condensed water, continuously reacting for 2.5h to obtain a side chainThe fluoroalkyl and the siloxy are co-modified polyurethane prepolymer.

4) Weighing 4.20g of perfluoroethyloctanol under the condition of 80 ℃, uniformly mixing with 8ml of acetone, dropwise adding the mixture into a reaction system within 2h, continuously heating and stirring for 1h, then weighing 0.39g of Pentaerythritol (PE), dissolving with 10ml of acetone, dropwise adding the mixture into the reaction system within 0.5h, continuously heating and stirring for 0.5h, adding 7.0g of solvent type silica sol (acetone type) with 30% of solid content, reacting for 1h, cooling to 40 ℃, adding 1.62g of Triethylamine (TEA) for neutralization, reacting for 0.5h, finally weighing 92g of deionized water, dropwise adding the deionized water under stirring for emulsification, rotatably steaming the prepared emulsion for 0.5h under the conditions of 50 ℃ and-0.1 MPa, removing the organic solvent, finally preparing the end/side fluoroalkyl co-modified polyurethane nano hybrid emulsion, spreading 30g of the emulsion in a polytetrafluoroethylene plate, naturally drying to prepare a polyurethane adhesive film, drying the polyurethane adhesive film in an oven at 50 ℃ after weeks.

The contact angle detection diagrams of the emulsion prepared in the examples 1 to 3 after film forming correspond to the diagrams 1 to 3 respectively, and the contact angles are 131.3 degrees, 129.4 degrees and 129.0 degrees in sequence. Among them, the preferred embodiment is the embodiment 1.

Referring to fig. 4, it can be seen that, compared to the product obtained in example 1, the temperature at 50% mass loss after film formation of the unmodified linear polyurethane PU was 293 ℃ only, the temperature at 50% mass loss after film formation of the polyurethane HBFPUF modified with organic fluorine only was 314 ℃ and the temperature at 50% mass loss after film formation of the polyurethane hbsifpf modified by the method was 334 ℃. In conclusion, the thermal stability of the adhesive film is improved well.

The invention is not limited to the examples, and any equivalent changes to the technical solution of the invention by a person skilled in the art after reading the description of the invention are covered by the claims of the invention.

Claims

1, preparation methods of terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion, which sequentially comprises the following steps:

1) synthesizing a micromolecular fluorine-containing chain extender:

putting 0.1mol of diethanolamine, 0.1mol of fluorine-containing acrylate monomer and 80g of absolute ethyl alcohol into a 250ml three-neck glass flask, reacting for 8 hours in an oil bath kettle at the temperature of 60 ℃, and then removing the solvent by rotary evaporation at the temperature of 50 ℃ and the pressure of-0.1 MPa to prepare the micromolecule fluorine-containing chain extender;

2) synthesizing a micromolecular silicon-containing chain extender:

slowly dropwise adding 0.2mol of hydroxyethyl acrylate into a 250ml three-neck flask containing 0.1mol of gamma-aminopropyltriethoxysilane and 0.0005mol of 4-methoxyphenol mixed solution under the ice bath condition, reacting at 40 ℃ for 6h after dropwise adding is finished, and then performing rotary evaporation at 50 ℃ and-0.1 MPa to remove the solvent to prepare the micromolecule silicon-containing chain extender;

synthesizing a side chain fluoroalkyl and siloxy co-modified polyurethane prepolymer:

taking a mixed solution of 0.05mol of isophorone diisocyanate and 0.0185mol of polyester or polyether diol as a raw material, taking 0.1ml of dibutyltin dilaurate as a catalyst, reacting for 1 hour at 80 ℃ in a 250ml three-neck glass flask, then sequentially adding 0.008mol of 2, 2-dimethylolpropionic acid, 0.004mol of 1, 4-butanediol, 0.004mol of micromolecule fluorine-containing chain extender and 0.004mol of micromolecule silicon-containing chain extender for chain extension reaction, simultaneously adding 10ml of solvent, and reacting for 2.5 hours at 80 ℃ to prepare a side chain fluoroalkyl and siloxy co-modified polyurethane prepolymer;

4) synthesizing end/side fluoroalkyl co-modified polyurethane nano hybrid emulsion:

slowly dripping 0.0115mol of organic fluorine alcohol into the reaction system under the condition that the temperature is 80 ℃, heating and stirring for 3 hours until the reaction is complete, and preparing the polyurethane with the end capped at the single side of the fluoroalkyl; dissolving 0.0038mol of cross-linking agent by using 10ml of solvent, dripping the cross-linking agent into the polyurethane with the end-capped on one side of the fluoroalkyl, reacting for 1 hour at 80 ℃ to prepare end fluoroalkyl and side chain fluoroalkyl co-modified polyurethane, adding solvent type silica sol (acetone type) with the solid content of 30 percent, and reacting for 1 hour; reducing the temperature of the system to 40 ℃, adding 0.008mol of triethylamine to neutralize for half an hour, then adding 93g of water to stir and disperse at high speed, and performing rotary evaporation for half an hour under the conditions of 50 ℃ and-0.1 Mpa to remove the solvent, thus obtaining the terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion with the solid content of 30%.

2. The preparation method of the terminal/side fluoroalkyl co-modified polyurethane nano hybrid emulsion according to claim 1, wherein the preparation method comprises the following steps:

the fluorine-containing acrylate in the step (1) is kinds of trifluoroethyl methacrylate, hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate;

the polyester or polyether diol in the step (3) is of polycaprolactone diol and polytetrahydrofuran diol;

the organic fluorine alcohol in the step (4) is kinds of perfluorohexyl alcohol and perfluoroethyl octanol, and is organic fluorine with single functional group, and is used for single-side end capping of the polyurethane prepolymer;

the cross-linking agent in the step (4) is of trimethylolpropane, triethanolamine and pentaerythritol.