CN110577653A - A kind of emulsion nanocomposite emulsion based on electrostatic self-assembly and preparation method thereof - Google Patents

Abstract

The invention discloses an emulsion nanocomposite emulsion based on electrostatic self-assembly and a preparation method thereof, which has the advantages of low cost, environment-friendly preparation method and good product stability, and can be used for leather retanning. The technical scheme of the present invention is: a preparation method of emulsion nano-composite emulsion based on electrostatic self-assembly, adopting a one-pot method to prepare water-based polyurethane, dispersing hydrotalcite in water, adding it in the polyurethane emulsification stage, and making hydrotalcite in the polyurethane matrix Disperse evenly, use the positive point of hydrotalcite and the negative charge of polyurethane to assemble the two, and prepare the emulsion nano-composite emulsion based on electrostatic self-assembly. The present invention uses hydrotalcite as a nanometer material to modify water-based polyurethane. The material is easy to manufacture and low in cost, the preparation method is simple and environmentally friendly, and the product has good stability; the prepared hydrotalcite-coated polyurethane nanocomposite emulsion can be used for leather restoration. Tanning can improve the dye absorption rate in the leather-making process, reduce waste water pollution, and endow the finished leather with certain flame-retardant properties.

Description

A kind of emulsion nanocomposite emulsion based on electrostatic self-assembly and preparation method thereof

technical field

The invention belongs to the field of polymer nanocomposite materials, and in particular relates to an emulsion nanocomposite emulsion based on electrostatic self-assembly and a preparation method thereof.

Background technique

Water-based polyurethane is a retanning agent with excellent comprehensive performance, because its molecular chain contains a large number of carbamate groups similar to the peptide chain structure (amide bond) of natural leather collagen, and its use in leather retanning can not only maintain the leather Natural hand, but also imparts excellent flexibility and dyeability to the leather. Traditional polyurethane retanning agents have disadvantages such as poor thermal stability, poor retanning performance, and single functionality. Therefore, proper modification of polyurethane retanning agent can improve the retanning performance of polyurethane and endow it with functionality.

Organic-inorganic nanocomposites combine organic and inorganic material properties, such as thermal stability, solubility, and processability, and are a new generation of composite materials with high performance and multiple functions. Using inorganic nano-materials, such as hydrotalcite, graphene and silica, etc., can enhance and modify the waterborne polyurethane matrix, which can not only effectively compensate for the defects of the matrix material itself and improve the thermal stability of the substrate, but also endow the composite Materials have new properties such as electrical and thermal conductivity, heat insulation, flame retardancy and adsorption.

Hydrotalcite is a layered metal hydroxide, which has the characteristics of enhancing the thermal stability of the matrix and endowing the matrix with adsorption and flame retardancy. Hydrotalcite has weak punctuality. When hydrotalcite is introduced into anionic polyurethane, due to the difference in charge between the two, self-assembly behavior will occur based on electrostatic force, forming a hydrotalcite-coated polyurethane nanocomposite emulsion. The nanocomposite material is used for leather retanning, which can play the role of retanning filling for leather; at the same time, the adsorption and flame retardancy of hydrotalcite can improve the dye adsorption rate in the retanning process, reduce the pollution of wastewater, and endow The finished leather has a certain flame retardant function.

Contents of the invention

The purpose of the present invention is to provide an emulsion nano-composite emulsion based on electrostatic self-assembly and its preparation method, which uses the characteristics of different electrical properties of hydrotalcite and polyurethane to make the two self-assemble, and the material is easy to manufacture and low in cost , the preparation method is simple and environmentally friendly, the product has good stability, and can be used for leather retanning.

In order to achieve the above object, the preparation method of a kind of emulsion nanocomposite emulsion based on electrostatic self-assembly provided by the present invention,

A one-pot method is used to prepare water-based polyurethane. Hydrotalcite is dispersed in water and added in the polyurethane emulsification stage, so that hydrotalcite is evenly dispersed in the polyurethane matrix. The positive point of hydrotalcite and the negative charge of polyurethane are used to assemble the two, and the base is prepared. Electrostatic Self-Assembled Emulsion Nanocomposite Emulsions.

The preparation method of described a kind of emulsion nano-composite emulsion based on electrostatic self-assembly, concrete steps are as follows:

Step 1, preparation of hydrotalcite nanosheets:

First, weigh 0.03~0.3mol of nitrate A, 0.03~0.2mol of nitrate B and 0.001~0.05mol of anhydrous sodium carbonate and dissolve them in 100~300mL of deionized water, adjust the pH to 6~13, and adjust the pH to 6~13. Stir and react at 100°C for 1-3 hours, then keep warm and crystallize for 10-18 hours. After the reaction is completed, filter, wash, dry, and grind to obtain hydrotalcite nanomaterials;

Nitrate A is Mg(NO ₃ ) ₂ , Ni (NO ₃ ) ₂ , Zn (NO ₃ ) ₂ , Ca (NO ₃ ) ₂ , Cu (NO ₃ ) ₂ , Cd (NO ₃ ) ₂ or Co(NO ₃ ) ₂ ;

Nitrate B is Al (NO ₃ ) ₃ , Ga (NO ₃ ) ₃ , In (NO ₃ ) ₃ or Cr (NO ₃ ) ₃ ;

Step 2, preparation of hydrotalcite-coated polyurethane nanocomposite emulsion:

First, weigh 10~20g polypolyol and heat it to 100~120°C, vacuumize and stir for 1~2h to completely dehydrate; then, lower the system temperature to 50~70°C, add 1~3g 2,2-dihydroxybutyl acid, dissolve and stir evenly, then continue to heat up to 70~90°C, add 3~9g of diisocyanate dropwise, heat preservation polymerization for 1~5h, stirring speed 200~400r/min; after the reaction, cool down to 40°C, add 0.5 - 2mL of triethylamine for neutralization; add the aqueous dispersion of hydrotalcite in the emulsification stage of water-based polyurethane, stir vigorously for 1 hour at a speed of 800-1200r/min, and then let stand to obtain a hydrotalcite-coated polyurethane nano-composite retanning agent.

In the second step, the preparation method of the aqueous dispersion of the hydrotalcite is to disperse the hydrotalcite with a mass fraction of 0wt%-10wt% in 40-100mL of water.

In the second step, the time for the emulsification reaction is 0.5-2 h, and the stirring speed during the emulsification reaction is 800-1400 r/min; the diisocyanate is toluene diisocyanate, diphenylmethane diisocyanate or isophorone diisocyanate.

In the first step, 1-3 mol/L NaOH aqueous solution is used to adjust the pH, the nitrate A is Mg(NO ₃ ) ₂ , and the nitrate B is Al (NO ₃ ) ₃ .

A hydrotalcite-coated polyurethane nanocomposite emulsion prepared by the above-mentioned preparation method.

Compared with prior art, the beneficial effect of the present invention is:

1. The present invention uses hydrotalcite as a kind of nano-material to modify water-based polyurethane, utilizes the characteristics of hydrotalcite and polyurethane with different electrical properties, makes the two self-assemble, and obtains a nanoemulsion of hydrotalcite-coated polyurethane, which The material is easy to manufacture with low cost, the preparation method is simple and environmentally friendly, and the product has good stability.

2. The hydrotalcite-coated polyurethane nanocomposite emulsion provided by the present invention can be used for leather retanning, can improve the dye absorption rate and reduce waste water pollution in the tanning process, and can also endow the finished leather with certain flame retardant properties.

Detailed ways

The present invention will be described in further detail below in conjunction with specific examples, but the embodiments of the present invention include but are not limited to the scope indicated in the following examples.

The invention uses hydrotalcite to modify the polyurethane, and coats the hydrotalcite nano sheet layer on the outer layer of the polyurethane to obtain a WPU@LDH nanocomposite emulsion. The composite emulsion has good organic-inorganic phase compatibility and stable emulsion.

The preparation method of hydrotalcite-coated polyurethane nanocomposite emulsion, the specific preparation steps are as follows:

Step 1: preparation of hydrotalcite nanosheets;

First, weigh 0.03~0.3mol of nitrate A, 0.03~0.2mol of nitrate B and 0.001~0.05mol of anhydrous sodium carbonate and dissolve them in 100~300mL of deionized water, and use 1~3mol/L NaOH aqueous solution to adjust pH to 6~13, stirred and reacted at a temperature of 70~100°C for 1~3h, then kept warm and crystallized for 10~18h, after the reaction was completed, filtered, washed, dried, and ground to obtain hydrotalcite nanomaterials;

Nitrate A is Mg(NO ₃ ) ₂ , Ni (NO ₃ ) ₂ , Zn (NO ₃ ) ₂ , Ca (NO ₃ ) ₂ , Cu (NO ₃ ) ₂ , Cd (NO ₃ ) ₂ or Co(NO ₃ ) ₂ ;

Nitrate B is Al (NO ₃ ) ₃ , Ga (NO ₃ ) ₃ , In (NO ₃ ) ₃ or Cr (NO ₃ ) ₃ ;

Step 2: preparation of hydrotalcite-coated polyurethane nanocomposite emulsion;

First, weigh 10~20g polypolyol and heat it to 100~120°C, vacuumize and stir for 1~2h to completely dehydrate; then, lower the system temperature to 50~70°C, add 1~3g 2,2-dihydroxybutyl acid, dissolve and stir evenly, then continue to heat up to 70~90°C, add 3~9g of diisocyanate dropwise, keep warm for 1~5h, and stir at a speed of 200~400r/min. After the reaction, the temperature was lowered to 40° C., and 0.5-2 mL of triethylamine was added for neutralization. Disperse 0wt%-10wt% hydrotalcite in 40-100mL water to prepare an aqueous dispersion of hydrotalcite. Add the aqueous dispersion of hydrotalcite in the emulsification stage of water-based polyurethane, stir vigorously for 1 hour at a speed of 800-1200r/min, and then let it stand still to obtain a hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion.

In step 1, nitrate A is Mg(NO ₃ ) ₂ , and nitrate B is Al (NO ₃ ) ₃ .

In step 2, the diisocyanate is toluene diisocyanate, diphenylmethane diisocyanate or isophorone diisocyanate.

Example 1

Step 1: preparation of hydrotalcite nanosheets;

First, weigh 0.2 mol of magnesium nitrate, 0.1 mol of aluminum nitrate and 0.04 mol of anhydrous sodium carbonate and dissolve them in 120 mL of deionized water, use 1 mol/L NaOH aqueous solution to adjust the pH to 10, and stir the reaction at a temperature of 80 °C 1h, then heat preservation and crystallization for 12h, after the reaction is completed, filter, wash, dry, and grind to obtain magnesium-aluminum hydrotalcite nanomaterials;

Step 2: Preparation of hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion;

First, weigh 20g of polyethylene glycol and heat it up to 120°C, vacuumize and stir for 2 hours to completely dehydrate; then, lower the temperature of the system to 60°C, add 1.25g of 2,2-dihydroxybutyric acid, dissolve and stir evenly, Continue to raise the temperature to 80° C., add 5.07 g of isophorone diisocyanate dropwise, heat-preserve polymerization for 3 hours, and stir at a speed of 300 r/min. After the reaction, the temperature was lowered to 40° C., and 1.18 mL of triethylamine was added for neutralization. Disperse 2wt% of hydrotalcite in 64mL of water to prepare an aqueous dispersion of hydrotalcite. In the emulsification stage of water-based polyurethane, the aqueous dispersion of hydrotalcite was added, vigorously stirred for 1 h at a speed of 1000 r/min, and then left to stand to obtain a hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion.

Example 2

Step 1: preparation of hydrotalcite nanosheets;

First, weigh 0.3 mol of zinc nitrate, 0.15 mol of aluminum nitrate and 0.05 mol of anhydrous sodium carbonate and dissolve them in 100 mL of deionized water, use 1 mol/L NaOH aqueous solution to adjust the pH to 10, and stir the reaction at a temperature of 85 °C 5h, then heat preservation and crystallization for 10h, after the reaction is completed, the zinc-aluminum hydrotalcite nanomaterial is obtained by filtering, washing, drying, and grinding;

Step 2: Preparation of hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion;

First, weigh 15g of polyethylene glycol and heat it up to 120°C, vacuumize and stir for 2 hours to completely dehydrate; then, lower the temperature of the system to 60°C, add 0.94g of 2,2-dihydroxybutyric acid, dissolve and stir evenly, Continue to raise the temperature to 80° C., add 3.8 g of isophorone diisocyanate dropwise, heat-preserve polymerization for 3 hours, and stir at a speed of 300 r/min. After the reaction, the temperature was lowered to 40° C., and 0.88 mL of triethylamine was added for neutralization. Disperse 6 wt% of hydrotalcite in 50 mL of water to prepare an aqueous dispersion of hydrotalcite. In the emulsification stage of water-based polyurethane, the aqueous dispersion of hydrotalcite was added, vigorously stirred for 1 h at a speed of 1000 r/min, and then left to stand to obtain a hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion.

Example 3

Step 1: preparation of hydrotalcite nanosheets;

First, weigh 0.3 mol of magnesium nitrate, 0.15 mol of aluminum iron nitrate and 0.05 mol of anhydrous sodium carbonate and dissolve them in 100 mL of deionized water, use 1 mol/L NaOH aqueous solution to adjust the pH to 9, and stir at a temperature of 85 °C React for 5 hours, then heat-preserve and crystallize for 10 hours. After the reaction is completed, filter, wash, dry, and grind to obtain magnesium-iron hydrotalcite nanomaterials;

Step 2: Preparation of hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion;

First, weigh 15g of polyethylene glycol and heat it up to 120°C, vacuumize and stir for 2 hours to completely dehydrate; then, lower the temperature of the system to 60°C, add 0.94g of 2,2-dihydroxybutyric acid, dissolve and stir evenly, Continue to raise the temperature to 80° C., add 3.8 g of isophorone diisocyanate dropwise, heat-preserve polymerization for 3 hours, and stir at a speed of 300 r/min. After the reaction, the temperature was lowered to 40° C., and 0.88 mL of triethylamine was added for neutralization. Disperse 4wt% of hydrotalcite in 50mL of water to prepare an aqueous dispersion of hydrotalcite. In the emulsification stage of water-based polyurethane, the aqueous dispersion of hydrotalcite was added, vigorously stirred for 1 h at a speed of 1100 r/min, and then left to stand to obtain a hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion.

Example 4

Step 1: preparation of hydrotalcite nanosheets;

First, weigh 0.2 mol of copper nitrate, 0.1 mol of aluminum nitrate and 0.04 mol of anhydrous sodium carbonate to dissolve in 900 mL of deionized water, use 1 mol/L NaOH aqueous solution to adjust the pH to 9, and stir the reaction at a temperature of 80 °C 2h, then heat preservation and crystallization for 10h, after the reaction is completed, filter, wash, dry, and grind to obtain copper-aluminum hydrotalcite nanomaterials;

Step 2: Preparation of hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion;

First, weigh 20g of polyethylene glycol and heat it up to 120°C, vacuumize and stir for 2 hours to completely dehydrate; then, lower the temperature of the system to 60°C, add 1.25g of 2,2-dihydroxybutyric acid, dissolve and stir evenly, Continue to raise the temperature to 80° C., add 5.07 g of isophorone diisocyanate dropwise, heat-preserve polymerization for 3 hours, and stir at a speed of 300 r/min. After the reaction, the temperature was lowered to 40° C., and 1.18 mL of triethylamine was added for neutralization. Disperse 10wt% of hydrotalcite in 65mL of water to prepare an aqueous dispersion of hydrotalcite. In the emulsification stage of water-based polyurethane, the aqueous dispersion of hydrotalcite was added, vigorously stirred for 2 h at a speed of 1200 r/min, and then left to stand to obtain a hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion.

In order to test the retanning performance of the hydrotalcite-coated polyurethane (WPU@LDH) nanocomposite emulsion prepared in the present invention, the inventors conducted a retanning application experiment on it, and obtained the nanocomposite materials with different hydrotalcite content by analysis. The effect of retanning. The blank polyurethane solution has poor dispersibility, and its microstructure is an irregular polymer of 500±100nm. After adding hydrotalcite, it self-assembles through electrostatic to form hydrotalcite-coated polyurethane microspheres with a particle size of 200±20nm. The composite material was used for the retanning of goat wet blue leather. Compared with the empty polyurethane, when the amount of magnesium aluminum hydrotalcite was 2wt%, the dye absorption rate increased from 94.8% to 98.0%, and the biological oxygen consumption of waste liquid The content (COD _Cr ) decreased from 4393mg/L to 3600mg/L, and the softness, mechanical properties and thickening rate of the finished leather were all improved. And the addition of hydrotalcite endows the finished leather with a certain flame retardant performance. When the amount of magnesium aluminum LDH is 8%, the flame retardant performance of the finished leather is the best, and the open flame time, the total amount of heat release and the heat release rate are all significantly reduced. .

The content of the present invention is not limited to the examples listed, and any equivalent transformation of the technical solution of the present invention adopted by those of ordinary skill in the art by reading the description of the present invention is covered by the claims of the present invention.

Claims (6)

1. A preparation method of an emulsion nano composite emulsion based on electrostatic self-assembly is characterized by comprising the following steps:

The method comprises the steps of preparing waterborne polyurethane by adopting a one-pot method, dispersing hydrotalcite in water, adding the hydrotalcite in a polyurethane emulsification stage to uniformly disperse the hydrotalcite in a polyurethane matrix, and assembling the hydrotalcite and the polyurethane by utilizing the positive point property of the hydrotalcite and the electronegativity of the polyurethane to prepare the emulsion nano composite emulsion based on electrostatic self-assembly.

2. The method for preparing the emulsion nanocomposite emulsion based on electrostatic self-assembly according to claim 1, wherein the method comprises the following steps:

the method comprises the following specific steps:

step one, preparing a hydrotalcite nano-sheet layer:

Firstly, 0.03 ~ 0.3.3 mol of nitrate A, 0.03 ~ 0.2.2 mol of nitrate B and 0.001 ~ 0.05.05 mol of anhydrous sodium carbonate are weighed and dissolved in 100 ~ 300mL of deionized water, the pH value is adjusted to 6 ~ 13, the mixture is stirred and reacted for 1 ~ 3h at the temperature of 70 ~ 100 ℃, then the mixture is subjected to heat preservation and crystallization for 10 ~ 18h, and after the reaction is finished, the hydrotalcite nano material is obtained through filtering, washing, drying and grinding;

Nitrate A being Mg (NO)₃)₂、Ni (NO₃)₂、Zn (NO₃)₂、Ca (NO₃)₂、Cu (NO₃)₂、Cd (NO₃)₂Or Co (NO)₃)₂；

Nitrate B being Al (NO)₃)₃、Ga (NO₃)₃、In (NO₃)₃Or Cr (NO)₃)₃；

step two, preparing the hydrotalcite-coated polyurethane nano composite emulsion:

firstly, weighing 10 ~ 20g of polyol, heating to 100 ~ 120 ℃, vacuumizing and stirring for 1 ~ 2h until complete dehydration, then reducing the temperature of the system to 50 ~ 70 ℃, adding 1 ~ 3g of 2, 2-dihydroxybutyric acid, dissolving and stirring uniformly, continuing to increase the temperature to 70 ~ 90 ℃, dropwise adding 3 ~ 9g of diisocyanate, carrying out heat preservation and polymerization for 1 ~ 5h at a stirring speed of 200 ~ 400r/min, reducing the temperature to 40 ℃ after the reaction is finished, adding 0.5-2mL of triethylamine for neutralization, adding the water dispersion of hydrotalcite in the emulsification stage of waterborne polyurethane, stirring vigorously for 1h at a rotation speed of 800-.

3. The method for preparing the emulsion nanocomposite emulsion based on electrostatic self-assembly according to claim 2, wherein the method comprises the following steps:

In the first step, a 1 ~ 3mol/L NaOH aqueous solution is used for adjusting the pH.

4. The method for preparing the emulsion nanocomposite emulsion based on electrostatic self-assembly according to claim 3, wherein the method comprises the following steps:

In the second step, the preparation method of the hydrotalcite aqueous dispersion comprises the step of dispersing hydrotalcite with the mass fraction of 0-10% in 40-100mL of water.

5. The method for preparing the emulsion nanocomposite emulsion based on electrostatic self-assembly according to claim 4, wherein the method comprises the following steps:

In the second step, the time of the emulsification reaction is 0.5 ~ 2h, the stirring speed during the emulsification reaction is 800 ~ 1400r/min, and the diisocyanate is toluene diisocyanate, diphenylmethane diisocyanate or isophorone diisocyanate.

6. a hydrotalcite coated polyurethane nanocomposite emulsion obtained by the process according to claims 1 to 5.