CN103739818A - Waterborne polyurethane-acrylic emulsion as well as preparation method and application thereof - Google Patents

Abstract

The invention provides a water-based polyurethane-acrylic emulsion and a preparation method and application thereof, which belong to the field of leather auxiliaries. The emulsion includes: 60-100 parts of polyether polyol, 40-80 parts of polyisocyanate monomer, 1-10 parts of polysiloxane, 30-60 parts of acrylate monomer, small molecular expansion 5-10 parts of chain agent, 5-12 parts of hydrophilic chain extender. The present invention also provides a method for preparing a water-based polyurethane-acrylic emulsion. In the method, isocyanate monomers, polyether polyols, hydrophilic chain extenders and organic silicon are gradually polymerized in proportion to prepare prepolymers, which are self-emulsified Anionic water-based polyurethane emulsion was synthesized by method, and acrylate monomer was added to continue polymerization to prepare double-modified water-based polyurethane emulsion. After the emulsion coating of the present invention forms a film, the tensile strength is ≥ 20 MPa, the elongation rate is ≥ 600%, has good surface properties and excellent comprehensive properties.

Description

Aqueous polyurethane-acrylic acid emulsion and its preparation method and application

technical field

The invention belongs to the field of leather auxiliary agents, and in particular relates to a water-based polyurethane-acrylic acid emulsion and a preparation method and application thereof.

Background technique

Water-soluble polyurethane for leather is an indispensable film-forming substance in the process of leather finishing. The water-based polyurethane finishing agent eliminates the flammable and explosive hazards in the production, storage, transportation and use of solvent-based polyurethane, and meets the requirements of safety and environmental protection. The leather coated with polyurethane emulsion has bright, plump, good hand feeling, wear resistance, and is not easy to wear. Fracture and other advantages can greatly improve the grade of finished leather. However, polyurethane also has its inherent disadvantages, such as poor water resistance, insufficient mechanical properties, and relatively expensive raw materials. The polyacrylic finishing agent has good mechanical properties, transparency, good weather resistance, and excellent water resistance, but it will have the defect of "hot stickiness and cold brittleness" with temperature. The composite two-component waterborne polyurethane combines the characteristics of polyurethane and polyacrylate, endowing the coating with more excellent performance.

Publication No. CN101307130B discloses a preparation method of anionic water-based polyurethane dispersion for leather finishing. The method adopts isocyanate containing rigid aromatic rings, and the prepared film is prone to yellowing. Publication No. CN102924683A discloses the preparation of water-based polyurethane dispersion for anti-yellowing leather finishing. However, due to the shortcomings of polyurethane itself such as poor water resistance and high cost, its comprehensive performance is not very ideal. Publication No. CN102408537A discloses a method for preparing acrylate-modified polyurethane emulsion for synthetic leather, but it adopts simple blending of polyacrylic acid emulsion and polyurethane emulsion, which is prone to phase separation during film formation.

Contents of the invention

The invention provides a water-based polyurethane-acrylic emulsion and its preparation method and application. The water-based polyurethane-acrylic emulsion has better comprehensive performance.

The present invention firstly provides a kind of water-based polyurethane-acrylic acid emulsion, according to parts by weight, comprising:

Preferably, the polyether polyol is selected from one or more of polyoxyethylene diol, polytetrahydrofuran diol, and polyoxypropylene diol.

Preferably, the polyisocyanate monomer is selected from one or more of isophorone diisocyanate (IPDI), hexacyclohexyl dicyanate (HMDI) or hexamethylene diisocyanate (HDI) .

Preferably, the polysiloxane is selected from one or both of hydroxyl-terminated polysiloxanes and amino-terminated polysiloxanes.

Preferably, the acrylate monomer is selected from one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate or butyl acrylate.

Preferably, the small molecule chain extender is selected from one or more of 1,4-butanediol, neopentyl glycol, ethylene glycol, and 2-methyl-1,3-propanediol.

Preferably, the hydrophilic chain extender is selected from one or more of dimethylol propionic acid, dimethylol butyric acid or dihydric alcohols containing sulfonic acid structures.

The present invention also provides a kind of preparation method of aqueous polyurethane-acrylic acid emulsion, comprises as follows:

Step 1: Add polyether polyol, polyisocyanate monomer, polysiloxane, hydrophilic chain extender, small molecule chain extender and catalyst into the reaction vessel, and react at 75-85°C for 4-6 hours to obtain prepolymer;

Step 2: Lower the temperature in the reaction vessel to 55-65°C, then add acrylate monomer, lower the temperature to 30-45°C, add neutralizer, react for 5-10 minutes, then add deionized water at room temperature Stir to obtain polyurethane emulsion;

Step 3: adding an initiator, an emulsifier and an acrylic monomer into a reaction vessel, and reacting at 70-85° C. for 2-6 hours to obtain a water-based polyurethane-acrylic emulsion.

Preferably, the catalyst is selected from one or more of dibutyltin dilaurate, dimethylethanolamine and triethylenediamine.

The invention also provides the application of the aqueous polyurethane-acrylic acid emulsion as a finishing agent in the field of leather.

Beneficial effects of the present invention

The invention provides a water-based polyurethane-acrylic acid emulsion. The structure of the water-based polyurethane-acrylic acid emulsion can effectively realize the emulsification of polyurethane due to the introduction of groups with anions into the hydrophilic group; due to the use of aliphatic isocyanate as a raw material, the preparation The emulsion has the characteristics of yellowing resistance and stability; polysiloxane is introduced into the polyurethane molecular chain, which improves the surface properties and film-forming properties of the emulsion; at the same time, the invention adds acrylate monomers, which can be used as solvents on the one hand , without adding other organic solvents, on the other hand, participate in the reaction to prepare double-modified water-based polyurethane emulsion.

The present invention also provides a method for preparing a water-based polyurethane-acrylic emulsion. In the method, isocyanate monomers, polyether polyols, hydrophilic chain extenders and organic silicon are gradually polymerized in proportion to prepare prepolymers, which are self-emulsified The anionic water-based polyurethane emulsion is synthesized by the method, and the acrylic ester monomer is added to continue polymerization to prepare a double-modified water-based polyurethane emulsion. The preparation method is simple, does not add organic solvents, reduces the organic solvent recovery process, and is environmentally friendly.

The present invention also provides an application of a water-based polyurethane-acrylic emulsion as a finishing agent in the field of leather. The water-based polyurethane-acrylic emulsion has the advantages of uniform particle size, moderate viscosity, and low surface tension. Tensile strength ≥ 20MPa, elongation ≥ 600%, with good surface properties and excellent comprehensive performance.

Description of drawings

Fig. 1 is the infrared spectrogram of a kind of aqueous polyurethane-acrylic acid emulsion prepared by the embodiment of the present invention 1;

Fig. 2 is the electron micrograph of a kind of water-based polyurethane-acrylic acid emulsion prepared in Example 1 of the present invention.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with the examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent requirements of the present invention.

The present invention firstly provides a kind of water-based polyurethane-acrylic acid emulsion, according to parts by weight, comprising:

60-100 parts of polyether polyol, 40-80 parts of polyisocyanate monomer, 1-10 parts of polysiloxane, 30-60 parts of acrylate monomer, 5-10 parts of small molecule chain extender, hydrophilic extender 5-12 parts of chain agent. Preferably: 70-90 parts of polyether polyol, 50-70 parts of polyisocyanate monomer, 3-6 parts of polysiloxane, 40-50 parts of acrylate monomer, 6-8 parts of small molecule chain extender, 7-10 parts of hydrophilic chain extender.

The polyether polyols described in the present invention are preferably selected from one or more of polyoxyethylene diols, polytetrahydrofuran diols, and polyoxypropylene diols, and the number-average molecular weight of the polyether polyols Preferably it is 1000-4000.

The polyisocyanate monomer described in the present invention is preferably an aliphatic diisocyanate monomer, more preferably selected from isophorone diisocyanate (IPDI), hexacyclohexyl dicyanate (HMDI) or hexamethylene diisocyanate ( One or more of HDI). Because the present invention uses the aliphatic isocyanate as the raw material, the prepared emulsion has the characteristics of yellowing resistance and stability.

The polysiloxane described in the present invention is preferably selected from one or both of hydroxyl-terminated polydimethylsiloxane and amino-terminated polysiloxane, and the number-average molecular weight of the polysiloxane is preferably For 500-2000. The invention introduces polysiloxane into the polyurethane molecular chain, improves the surface performance and film-forming property of the emulsion, and improves the comprehensive performance of the emulsion.

The acrylate monomers described in the present invention are preferably selected from one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate or butyl acrylate, more preferably methyl methacrylate and butyl acrylate, in the mixture, the mass ratio of methyl methacrylate and butyl acrylate is 1:1. The present invention uses the raw material acrylate monomer to have two effects, on the one hand, it is used as a solvent without adding other organic solvents, which reduces the organic solvent recovery process; on the other hand, it is used as a raw material monomer to participate in the reaction to prepare double-modified water-based polyurethane emulsion.

The small molecule chain extender in the present invention is preferably selected from one or more of 1,4 butanediol, neopentyl glycol, ethylene glycol, and 2-methyl-1,3-propanediol. The hydrophilic chain extender is preferably selected from one or more of dimethylol propionic acid, dimethylol butyric acid or diols containing sulfonic acid structures, and the dihydric alcohols containing sulfonic acid structures The alcohol is preferably sodium ethylenediurethanesulfonate.

The present invention also provides a kind of preparation method of aqueous polyurethane-acrylic acid emulsion, comprises as follows:

Step 1: Add polyether polyol, polyisocyanate monomer, polysiloxane, hydrophilic chain extender, small molecule chain extender and catalyst into the reaction vessel, and react at 75-85°C for 4-6 hours to obtain prepolymer;

Step 2: Lower the temperature in the reaction vessel to 55-65°C, then add a part of acrylate monomer, lower the temperature to 30-45°C, add neutralizer, react for 5-10 minutes, add deionized Stir with water to obtain polyurethane emulsion;

Step 3: adding an initiator, an emulsifier and the remaining acrylic ester monomers into a reaction vessel, and reacting at 70-85° C. for 2-6 hours to obtain a water-based polyurethane-acrylic acid emulsion.

In step 1 of the present invention, after adding polyether polyol into the reaction vessel, vacuum dehydration is preferably carried out at 110-120°C for 1-2 hours, and then polysiloxane, hydrophilic chain extender, small molecule Chain extender and catalyst, raise the temperature to 75-85°C, add polyisocyanate monomer after the above mixed solution is melted, and react for 4-6 hours until the -NCO value reaches the theoretical value to obtain a prepolymer; the catalyst It is preferably one or more selected from dibutyltin dilaurate, dimethylethanolamine, and triethylenediamine. The catalyst is preferably 0.01-0.1 part by weight.

In step 2 of the present invention, after the temperature is lowered to 55-65°C, a part of acrylate monomer is added to the reaction vessel, and the acrylate monomer is used as a diluent to replace traditional acetone to reduce the viscosity of the system. The amount of acrylate monomer added accounts for 50% of the total amount of acrylate monomer added in the reaction process; then the temperature is lowered to 30-45°C, and a neutralizing agent is added to neutralize and form a salt. The neutralizing agent Preferably one or more selected from triethylamine, tripropylamine or 2-methylethanolamine. The amount of neutralizing agent added is 80% to 120% of the amount of carboxyl groups in the monomer; the stirring speed is preferably 1000 to 2000 rpm, and the stirring time is preferably 20 to 40 minutes after adding deionized water.

In Step 3 of the present invention, the temperature of the reaction vessel is raised to 70-75°C, and then a part of the initiator, emulsifier and remaining acrylate monomers are added, and the heat preservation reaction is carried out for 1-3 hours. The amount of addition is 50-80% of the total amount of initiators, and then the temperature is raised to 80-85°C, then the remaining initiators are added, the reaction is continued for 1-3 hours, the temperature is lowered and the material is discharged to obtain a water-based polyurethane-acrylic emulsion.

The initiator described in the present invention is preferably selected from one of potassium persulfate, ammonium persulfate, oil-soluble AIBN or BPO. The total addition amount of the initiator is 0.5-3% of the weight of the propionic acid ester monomer, preferably 1%.

The emulsifier described in the present invention is preferably selected from one of sodium dodecylbenzenesulfonate (SDS), sodium dodecylsulfate or sodium alkylsulfonate. The addition amount of the emulsifier is 0.3-2% by weight of the propionic acid ester monomer, preferably 1%. The amount of the remaining acrylic ester monomer added accounts for 50-60% of the total amount of acrylic ester monomer added during the reaction process.

The invention also provides the application of the aqueous polyurethane-acrylic acid emulsion as a finishing agent in the field of leather.

The present invention will be further described in detail below in conjunction with the examples.

Example 1

Add 100 g of polytetrahydrofuran diol (data molecular weight: 4000) into a three-necked flask equipped with a stirring device, a condenser, and a thermometer, vacuumize and dehydrate at a temperature of 120°C for 1 hour, and then add a hydrophilic chain extender, dimethylol Propionic acid 12g, chain extender 1,4-butanediol 10g, hydroxyl-terminated polydimethylsiloxane (data molecular weight: 2000) 10g and catalyst dibutyltin dilaurate 0.1g, under the protection of dry nitrogen, The temperature is controlled at 85°C, and after the above mixed solution is melted, 80 g of isophorone diisocyanate is added at one time, and reacted for 4 hours until the -NCO value reaches the theoretical value to obtain a prepolymer;

Lower the temperature in the three-necked flask to 60°C, then add 30g of methyl methacrylate and butyl acrylate mixture for dilution (mass ratio is 1:1), lower the temperature to 40°C, add 4g of triethylamine, react for 5min, Add deionized water at room temperature, stir and disperse at a speed of 1300 rpm for 30 minutes for emulsification to obtain a polyurethane emulsion;

Raise the temperature in the three-necked flask to 75°C, add 1.2g of emulsifier SDS, 1.4g of initiator potassium persulfate, and 30g of the remaining mixture of methyl methacrylate and butyl acrylate (mass ratio: 1:1), and keep warm for the reaction After 2 hours, the temperature was raised to 80° C., 0.4 g of potassium persulfate was added, and the reaction was continued for 2 hours to obtain a polyurethane-acrylic acid emulsion. The obtained polyurethane-acrylic emulsion was subjected to a performance test, and the results are shown in Table 1.

Fig. 1 is the infrared spectrogram of a kind of water-based polyurethane-acrylic emulsion prepared in Example 1 of the present invention, as can be seen from the figure, the present invention successfully prepared polyurethane-acrylic emulsion.

Fig. 2 is the electron micrograph of a kind of water-based polyurethane-acrylic acid emulsion prepared in Example 1 of the present invention. It can be seen from Figure 2 that the distribution of emulsion particles is relatively uniform, and the particle size is within a reasonable range.

Example 2

Add 60g of polyoxyethylene glycol (data molecular weight: 1000) into a three-necked flask equipped with a stirring device, a condenser, and a thermometer, vacuumize and dehydrate at a temperature of 120°C for 1 hour, and then add a hydrophilic chain extender dihydroxy Methylbutyric acid 5g, chain extender neopentyl glycol 5g, hydroxyl-terminated polydimethylsiloxane (data molecular weight: 500) 1g and catalyst dimethylethanolamine 0.01g, under the protection of dry nitrogen, the temperature is controlled at 75°C, after the above mixture is melted, add 40 g of hexacyclohexyl dicyanate at one time, react for 6 hours until the -NCO value reaches the theoretical value, and obtain a prepolymer;

Lower the temperature in the three-necked flask to 55°C, then add 15g of ethyl methacrylate, lower the temperature to 30°C, add 5g of tripropylamine to neutralize and form a salt, react for 10min, add deionized water at room temperature, Stir and disperse under the rotating speed of 10 minutes and carry out emulsification for 30 minutes, obtain polyurethane emulsion;

Raise the temperature in the three-necked flask to 70°C, add 0.09 g of emulsifier sodium lauryl sulfate, 0.1 g of initiator ammonium persulfate, and 15 g of the remaining ethyl methacrylate, keep the temperature for 3 hours, and raise the temperature to 80 °C, 0.05 g of ammonium persulfate was added, and the reaction was continued for 3 hours to obtain an aqueous polyurethane-acrylic emulsion. The obtained polyurethane-acrylic emulsion was subjected to a performance test, and the results are shown in Table 1.

Example 3

Add 70g of polyoxypropylene glycol (data molecular weight: 2000) into a three-necked flask equipped with a stirring device, a condenser, and a thermometer, vacuumize and dehydrate at a temperature of 120°C for 1 hour, and then add a hydrophilic chain extender dihydroxy 7g of methacrylic acid, 6g of chain extender ethylene glycol, 3g of amino-terminated polysiloxane (data molecular weight: 1000) and 0.02g of catalyst triethylenediamine, under the protection of dry nitrogen, the temperature is controlled at 80°C, and the After the above mixed solution was melted, 50 g of hexamethylene diisocyanate was added at one time, and reacted for 5 hours until the -NCO value reached the theoretical value to obtain a prepolymer;

Lower the temperature in the three-necked flask to 65°C, then add 20g of butyl methacrylate, lower the temperature to 45°C, add 6g of 2-methylethanolamine to neutralize and form a salt, react for 7min, add deionized water at room temperature, and Stir and disperse for 30 minutes under the rotating speed of revolution per minute and carry out emulsification, obtain polyurethane emulsion;

Raise the temperature in the three-necked flask to 75°C, add 0.4g of emulsifier sodium alkylsulfonate, 0.2g of initiator oil-soluble AIBN, and the remaining butyl methacrylate 20g, keep the temperature for 1 hour, and raise the temperature to 85°C , add 0.2 g of oil-soluble AIBN, and continue to react for 1 hour to obtain a water-based polyurethane-acrylic acid emulsion. The obtained polyurethane-acrylic emulsion was subjected to a performance test, and the results are shown in Table 1.

Example 4

Add 90 g of polytetrahydrofuran ether (data molecular weight: 2000) into a three-necked flask equipped with a stirring device, a condenser, and a thermometer, vacuumize and dehydrate at a temperature of 120°C for 1 hour, and then add a hydrophilic chain extender, dimethylolpropane Acid 10g, chain extender 1,4-butanediol 8g, hydroxyl-terminated polydimethylsiloxane (data molecular weight: 2000) 6g and catalyst dibutyltin dilaurate 0.05g, under dry nitrogen protection, temperature control At 85°C, add 70 g of isophorone diisocyanate at one time after the above mixture is melted, and react for 4 hours until the -NCO value reaches the theoretical value to obtain a prepolymer;

Lower the temperature in the three-necked flask to 60°C, then add 25g of a mixture of methyl methacrylate and butyl acrylate for dilution (mass ratio 1:1), lower the temperature to 40°C, add 5g of triethylamine to neutralize and form a salt , react for 5 minutes, add deionized water at room temperature, stir and disperse for 30 minutes at a rotating speed of 1300 rpm to emulsify, and obtain a polyurethane emulsion;

Raise the temperature in the three-necked flask to 75°C, add 0.5g of emulsifier SDS, 0.3g of initiator BPO, and 25g of the remaining mixture of methyl methacrylate and butyl acrylate (mass ratio: 1:1), and keep warm for the reaction After 2 hours, the temperature of the above-mentioned emulsion was raised to 80° C., 0.2 g of BPO was added, and the reaction was continued for 2 hours to obtain a water-based polyurethane-acrylic acid emulsion. The obtained polyurethane-acrylic emulsion was subjected to a performance test, and the results are shown in Table 1.

Table 1

The descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. an aqueous polyurethane-acrylic acid emulsion, characterized in that, in parts by weight, comprising:

2. a kind of aqueous polyurethane-acrylic acid emulsion according to claim 1, is characterized in that, described polyether polyol is selected from polyoxyethylene glycol, polytetrahydrofuran glycol, polyoxypropylene glycol one or more of. 3. A kind of aqueous polyurethane-acrylic acid emulsion according to claim 1, is characterized in that, described polyisocyanate monomer is selected from isophorone diisocyanate, hexamethylene dicyanate or hexamethylene dicyanate One or more of the isocyanates. 4. A kind of waterborne polyurethane-acrylic acid emulsion according to claim 1, is characterized in that, described polysiloxane is selected from one or in hydroxyl-terminated polysiloxane or amino-terminated polysiloxane two kinds. 5. A kind of aqueous polyurethane-acrylic acid emulsion according to claim 1, is characterized in that, described acrylic acid ester monomer is selected from methyl methacrylate, ethyl methacrylate, butyl methacrylate or acrylic acid One or more of butyl esters. 6. a kind of water-based polyurethane-acrylic acid emulsion according to claim 1, is characterized in that, described small molecular chain extender is selected from 1,4 butanediol, neopentyl glycol, ethylene glycol, 2-formazol One or more of the base-1,3-propanediols. 7. A kind of waterborne polyurethane-acrylic acid emulsion according to claim 1, is characterized in that, described hydrophilic chain extender is selected from dimethylol propionic acid, dimethylol butyric acid or containing sulfonic acid structure One or more of dihydric alcohols. 8. a preparation method of water-based polyurethane-acrylic acid emulsion, is characterized in that, comprises as follows: Step 1: Add polyether polyol, polyisocyanate monomer, polysiloxane, hydrophilic chain extender, small molecule chain extender and catalyst into the reaction vessel, and react at 75-85°C for 4-6 hours to obtain prepolymer; Step 2: Lower the temperature in the reaction vessel to 55-65°C, then add acrylate monomer, lower the temperature to 30-45°C, add neutralizer, react for 5-10 minutes, then add deionized water at room temperature Stir to obtain polyurethane emulsion; Step 3: adding an initiator, an emulsifier and an acrylic monomer into a reaction vessel, and reacting at 70-85° C. for 2-6 hours to obtain a water-based polyurethane-acrylic emulsion. 9. the preparation method of a kind of aqueous polyurethane-acrylic acid emulsion according to claim 8, is characterized in that, described catalyst is selected from the one in dibutyltin dilaurate, dimethylethanolamine, triethylenediamine or Several kinds. 10. the application of a kind of aqueous polyurethane-acrylic acid emulsion described in any one in claim 1-9 as finishing agent in leather field.

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