CN108467463A - A kind of water proof type aqueous coating polyurethane-polyacrylate composite emulsion and preparation method thereof - Google Patents

Abstract

A kind of water proof type aqueous coating urethane acrylate complex emulsions of present invention offer and preparation method thereof, belong to water-repellent paint field.The lotion according to weight fraction meter, including：50~100 parts of polyether polyol, 30~70 parts of polyisocynate monomer, 6~17 parts of polysiloxanes, 30~70 parts of acrylate monomer, 4~10 parts of small molecule chain extender, 5~15 parts of hydrophilic chain extender, 3~10 parts of salt forming agent.The present invention also provides a kind of preparation methods of water proof type aqueous coating polyurethane polyacrylate complex emulsions.Emulsion particle prepared by this method is semi IPN (half network interpenetrating) structure.After the lotion of the present invention covers with paint, lacquer, colour wash, etc. film forming, water-tolerant, film formation at low temp be good, high glaze, water contact angle >=88 °, water absorption rate≤10%, mechanical property is good, excellent combination property, the application that can be used on water-repellent paint.

Description

Water-based polyurethane-polyacrylate composite emulsion and preparation thereof for waterproof coating preparation method

technical field

The invention belongs to the technical field of coatings, and in particular relates to a water-based polyurethane-polyacrylate composite emulsion for waterproof coatings and a preparation method thereof.

Background technique

In today's society, people pursue the principles of economy, efficiency, ecology and energy to develop the coatings industry. In response to the requirements of safety and environmental protection, water-based polyurethane will gradually replace the application of traditional solvent-based polyurethane. Compared with traditional solvent-based polyurethane, water-based polyurethane has the advantages of non-toxic, non-flammable, and low temperature resistance. However, water-based polyurethane also has its inherent disadvantages, such as poor water resistance, poor mechanical properties, poor light resistance, and relatively expensive raw materials. Polyacrylates have many outstanding advantages, such as excellent light resistance, weather resistance, acid and alkali resistance, and mechanical properties, but they tend to become brittle at low temperature and sticky at high temperature. Utilizing the complementary properties of polyurethane core and polyacrylate, the polyurethane-polyacrylate composite material with excellent performance can be obtained by modifying polyurethane through acrylate.

The Chinese patent with the publication number CN105482060 discloses a method of RAFT (reversible addition-fragmentation chain transfer polymerization) to prepare a chemically bonded core-shell aqueous polyurethane-acrylate copolymer emulsion, although a polyurethane with a controllable core-shell composition has been obtained. - Acrylate emulsions, but RAFT chain transfer agents may impart some color and odor to the polymer, and their removal and conversion are more difficult.

Contents of the invention

The purpose of the present invention is to provide a water-based polyurethane-polyacrylate composite emulsion for waterproof coatings and a preparation method thereof in order to solve the problems of poor water resistance and low-temperature film-forming properties of existing water-based polyurethane-acrylate emulsion products.

The present invention firstly provides a water-based polyurethane-polyacrylate emulsion for waterproof coatings, the emulsion is an anionic water-based polyurethane emulsion synthesized by a self-emulsification method, and then the acrylate monomer is dispersed into the polyurethane system by pre-swelling for polymerization Obtained, the prepared emulsion particle is semi-IPN structure; The emulsion includes as follows in parts by weight:

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

Preferably, the polyisocyanate monomer is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate.

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

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

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

Preferably, the hydrophilic chain extender is selected from one or more of dimethylolpropionic acid, dihydroxy half ester, sodium ethylenediaminoethanesulfonate, diethylenetriamine or methyldiethanolamine. kind.

Preferably, the salt-forming agent is selected from one of triethylamine, ammonia water or sodium hydroxide.

The present invention also provides a preparation method of water-based polyurethane-polyacrylate composite emulsion for waterproof coating, comprising the steps of:

Step 1: Add polyether polyol, polyisocyanate, polysiloxane, small molecule chain extender, hydrophilic chain extender and catalyst into the reaction vessel, and react at 75-95°C for 2-4 hours to obtain a prepolymer ;

Step 2: Lower the temperature in the reaction vessel to 30-40°C, add acetone to reduce viscosity, continue to react for 20-40 minutes, then add salt-forming agent, react for 5-10 minutes, add deionized water at room temperature and stir to obtain aqueous polyurethane emulsion;

Step 3: Add acrylate monomers to the obtained water-based polyurethane emulsion, pre-swell at 25°C for 12-24 hours, and add 1/3 emulsifier at the same time, after the pre-swelling is completed, raise the reaction temperature to 65-80°C , adding initiator and remaining emulsifier, nitrogen protection, stirring and reacting for 3-7 hours to obtain water-based polyurethane-polyacrylate composite emulsion for waterproof coating.

Preferably, the stirring speed in the third step is 250-300 rpm.

Beneficial effects of the present invention

The invention provides a water-based polyurethane-polyacrylate emulsion for waterproof coatings. Since aliphatic isocyanate is used as a raw material, the prepared emulsion has the characteristics of yellowing resistance and stability; it introduces organic silicon segments into the main chain of polyurethane molecules , which reduces the surface energy of the membrane and improves the water resistance of the membrane; at the same time, the present invention adds acrylic monomers through pre-swelling to obtain a double-modified water-based polyurethane with a semi-interpenetrating network structure (semi-IPN structure) Emulsion, this special structure can improve the water resistance of the film. The water-based polyurethane-polyacrylate emulsion has a solid content of 30%-40%, a particle size of 80-140nm, a storage stability of more than 6 months, and has the advantages of moderate emulsion viscosity, uniform particle size and good stability. The experimental results show that after coating and forming a film, the water resistance is outstanding, the contact angle is ≥88°, the water absorption rate is ≤10%, the mechanical properties are good, and the comprehensive performance is excellent.

The present invention also provides a method for preparing a water-based polyurethane-polyacrylate composite emulsion for waterproof coatings. The method is to gradually prepare polyisocyanate monomers, polyether polyols, hydrophilic chain extenders and organic silicon according to the proportion. Polymerization, first prepare a prepolymer, synthesize an anionic water-based polyurethane emulsion through self-emulsification, then disperse the acrylate monomer into the polyurethane system by pre-swelling, continue polymerization, and prepare a double-modified water-based polyurethane emulsion. The emulsion particles prepared by the method have a semi-IPN (semi-interpenetrating network) structure. The preparation method is simple, the raw materials are easy to obtain, and the prepared product has excellent comprehensive properties.

Description of drawings

Fig. 1 is the transmission electron microscope picture of a kind of waterproof coating water-based polyurethane-polyacrylate composite emulsion particle prepared in Example 1 of the present invention;

Fig. 2 is a water contact angle and water absorption diagram of a water-based polyurethane-polyacrylate composite emulsion for a waterproof coating 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 specific 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 water-based polyurethane-polyacrylate composite emulsion for waterproof coatings. The anionic water-based polyurethane emulsion is synthesized through a self-emulsification method, and then the acrylate monomer is dispersed into the polyurethane system by pre-swelling. Obtained by polymerization, the prepared emulsion particles have a semi-IPN structure; the emulsion includes in parts by weight:

Polyether polyol 50-100, polyisocyanate 30-80, acrylate monomer 30-70, polysiloxane 6-17, small molecule chain extender 4-10, hydrophilic chain extender 5- 15 parts, 3 to 10 parts of salt forming agent. Preferably: polyether polyol 60-90, polyisocyanate 40-70, polysiloxane 7-15 parts, small molecule chain extender 5-8 parts, hydrophilic chain extender 7-10 parts, salt-forming agent 7 parts ～10 parts, 30～60 parts of acrylate monomer.

The polyether polyol of the present invention is selected from one or more of polyoxyethylene ether diol, polytetrahydrofuran ether diol, and polyoxypropylene diol, and the number average molecular weight of the polyol is preferably 1000～ 3000.

The polyisocyanate monomers described in the present invention are selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, and the aliphatic diisocyanate used in the present invention Using isocyanate as raw material, the prepared emulsion has the characteristics of yellowing resistance and stability.

The polysiloxane of the present invention is selected from one or more of hydroxyl-terminated polysiloxane, hydroxyalkyl-terminated polysiloxane or amino-terminated polysiloxane, and the polysiloxane The number-average molecular weight of the alkane is preferably 500-2000, and polysiloxane is introduced into the main chain of the polyurethane molecule, which reduces the surface properties of the film and improves the water resistance of the film.

The acrylate monomers described in the present invention are selected from one or more of butyl acrylate, methyl methacrylate, ethyl methacrylate or butyl methacrylate, preferably methyl methacrylate and acrylic acid A mixture of butyl esters, and the mass ratio of methyl methacrylate to butyl acrylate is 1:1. In the present invention, the acrylate monomer is added to the reaction system by pre-swelling, and this pre-swelling method can obtain a semi-network interpenetrating structure (semi-IPN structure), and the semi-IPN structure will endow the film with excellent water resistance sex.

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

The hydrophilic chain extender in the present invention is selected from one or more of dimethylolpropionic acid, dihydroxy half ester, sodium ethylenediaminoethanesulfonate, diethylenetriamine or methyldiethanolamine.

The salt-forming agent described in the present invention is selected from one of triethylamine, ammonia water or sodium hydroxide.

The present invention also provides a method for preparing a water-based polyurethane-polyacrylate composite emulsion for waterproof coatings, comprising the following steps:

Step 1: Add polyether polyol, polyisocyanate, polysiloxane, small molecule chain extender, hydrophilic chain extender and catalyst into the reaction vessel, and react at 75-95°C for 2-4 hours to obtain a prepolymer ;

Step 2: Lower the temperature in the reaction vessel to 30-40°C, add acetone to reduce the viscosity, continue the reaction for 20-40 minutes, then add the salt-forming agent, react for 5-10 minutes, add deionized water at room temperature (25°C) Stir to obtain aqueous polyurethane emulsion;

Step 3: Add acrylate monomers to the obtained water-based polyurethane emulsion, pre-swell at 25°C for 12-24 hours, and add 1/3 emulsifier at the same time, after the pre-swelling is completed, raise the reaction temperature to 65-80°C , adding initiator and remaining emulsifier, nitrogen protection, stirring and reacting for 3-7 hours to obtain water-based polyurethane-polyacrylate composite emulsion for waterproof coating. In step 1 of the present invention: first place the polyether polyol used for the reaction in a vacuum oven at 80-100°C to remove water under vacuum for 1-2 hours, after the dehydration is completed, the material is cooled, and then polyisocyanate, polysiloxane , small molecule chain extender, hydrophilic chain extender and catalyst are added to the reaction kettle, and the stirring device and heating device are turned on to react at 75-95°C for 2-4 hours. The stirring speed is preferably 300-400 rpm Nitrogen protection, when the -NCO value reaches the theoretical value, a prepolymer is prepared; the catalyst is selected from N, N-dimethylcyclohexylamine, N, N-dimethylethanolamine, N, N-dimethyl One of pyridine, stannous octoate and dibutyltin dilaurate. The catalyst is preferably 0.01-0.1 part by weight fraction.

In the second step of the present invention: the temperature in the reaction vessel is lowered to 30-40°C, then 30-60ml of acetone is added to reduce the viscosity for 20-40 minutes, then a salt-forming agent is added, reacted for 5-10 minutes, and then deionized water is added, Stir at a high speed at room temperature for 30-50 minutes, preferably at a stirring speed of 1000-2000 rpm, to obtain an aqueous polyurethane emulsion.

In the third step of the present invention: add acrylate monomers to the obtained water-based polyurethane emulsion, pre-swell for 12-24 hours at 25°C, that is, mechanically stir for 12-24 hours at room temperature, preferably the pre-swelling time is 14-16 hours, Add 1/3 of the emulsifier at the same time, after pre-swelling for 14-16 hours, raise the reaction temperature to 65-80°C, add the initiator and the remaining emulsifier, under nitrogen protection, stir for 3-7 hours, the stirring speed is preferably 250 ~300 rev/min, remove acetone by vacuum distillation to obtain water-based polyurethane-polyacrylate composite emulsion.

According to the present invention, the pre-swelling time of step 3 and the reaction temperature and time after the pre-swelling are all key parameters to control the reaction. The pre-swelling time of the present invention is 12-24h. If the time is too short, the monomer It exists in the form of large droplets. Under mechanical stirring, the monomer droplets will become smaller and affect the pre-swelling effect; if the time is too long, it will affect the stability of the polyurethane water dispersion system. The reaction temperature is 65-80°C. If the temperature is too low, the decomposition temperature of the initiator will not be reached, and the reaction effect will be poor. If the temperature is too high, part of the water will evaporate, which will affect the solid content.

The preparation method of the water-based polyurethane-polyacrylate composite emulsion of the waterproof coating of the present invention is to first synthesize polyurethane and disperse it with water to form water-based polyurethane, and then perform pre-swelling. The purpose of pre-swelling is to disperse monomers in the entire water-based polyurethane system In the process, due to the certain hydrophobicity of the acrylate monomer itself, most of the monomers will swell and enter the polyurethane micelle particles, and a small part of the monomers are still free in the water phase. After the free radical polymerization of the second part of the acrylate monomer, after adding the initiator, most of the monomers are polymerized inside the PU, and the monomers free in the water phase outside the PU will also continue with the long chain generated inside. The reaction forms an interpenetrating network structure, because there is no introduction of functional monomers (such as hydroxyethyl methacrylate HEMA, which has -OH at one end and unsaturated double bonds at one end, and -OH reacts with polyurethane to form a The prepolymer with unsaturated double bonds at the end,) HEMA can be used as a bridge to connect the acrylate monomer to the PU chain, thus forming a polyurethane-polyacrylate copolymer structure with chemical bonds. Simultaneously in this system of the present invention, also added organosilicon (polysiloxane), the characteristic of organosilicon is that surface energy is low, and in the process of emulsion film formation, silicon segment can migrate to film surface, can reduce film The surface energy of the surface also improves the water resistance of the membrane surface. Here, the migration of the silicon segment will be affected by the structure. It has no strong molecular force such as chemical bonds, and the molecular chain is easy to move and deform. In this way, the silicon segment is easy to migrate to the surface of the membrane, which improves the water resistance of the membrane surface.

The initiator described in the present invention is selected from one of potassium persulfate, ammonium persulfate, azobisisobutylcyanide and benzoyl peroxide. The dosage of the initiator is 0.5%-2% of the weight of the acrylate monomer, preferably 1%.

The emulsifier in the present invention is selected from sodium dodecyl sulfate (SDS), sodium dodecylsulfonate or sodium dodecylbenzenesulfonate (SDBS). The total amount of the emulsifier is 1%-4% of the weight of the acrylate monomer, preferably 3%.

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

Example 1

In a four-necked flask equipped with a stirring device, a condenser, a thermometer and nitrogen, add 80 g of polytetrahydrofuran ether diol (number average molecular weight: 2000), vacuumize and dehydrate at 100°C for 2 hours, and then add isophor Ketone diisocyanate 60g, hydrophilic chain extender dimethylol propionic acid 10g, small molecule chain extender 1,4-butanediol 8g, dihydroxyl-terminated polydimethylsiloxane (number average molecular weight is 1000) 10g and catalyst dibutyltin dilaurate 0.1g, under nitrogen protection throughout the process, the temperature of the oil bath was controlled at 80°C, the stirring speed was 380 rpm, and the reaction was carried out for 3 hours until -NCO reached the theoretical value to obtain a prepolymer;

Lower the temperature in the reactor to 40°C, add 50ml of acetone to reduce the viscosity for 30 minutes, then lower the temperature to 25°C, add 3g of salt-forming agent triethylamine, react for 10 minutes, then add deionized water, at 1200 rpm High-speed stirring under the rotating speed of 30 minutes carries out emulsification, obtains water-based polyurethane emulsion;

In the aqueous polyurethane emulsion obtained, add 50g (its mass ratio is 1:1) of the mixture of methyl methacrylate and butyl acrylate, add 0.5g emulsifier sodium dodecyl sulfate (SDS) simultaneously, under 25 ℃, pre- Swell for 14 hours (that is, mechanically stir for 14 hours at room temperature), and the stirring speed is 300 rpm. After 14 hours of pre-swelling, the reaction temperature is raised to 70 ° C, and 0.5 g of initiator azobisisobutylcyanide and remaining emulsified Agent 1g, under the protection of nitrogen, stirred and reacted for 5 hours to obtain a water-based polyurethane-polyacrylate composite emulsion.

The obtained aqueous polyurethane-polyacrylate emulsion and coating film were tested and characterized, and the results are shown in Table 1.

Fig. 1 is a transmission electron microscope photograph of a kind of water-based polyurethane-polyacrylate emulsion prepared in Example 1 of the present invention. It can be seen from Figure 1 that the distribution of emulsion particles is relatively uniform, the particle size is within a reasonable range, and the structure of the particles is a semi-IPN (semi-interpenetrating network) structure.

Fig. 2 is the water absorbency and the water contact angle test of the coating film of a kind of aqueous polyurethane-polyacrylate emulsion prepared in the embodiment of the present invention 1, as can be seen from Fig. 2, its contact angle reaches 93.1 °, and water absorption rate is 9.61 %, the water resistance of the coating film is better.

Example 2

In a four-necked flask equipped with a stirring device, a condenser, a thermometer and nitrogen, add 60 g of polyoxyethylene diol (number average molecular weight: 1000), vacuumize and dehydrate at 100 ° C for 2 hours, and then add hexamethylene Diisocyanate 40g, hydrophilic chain extender methyldiethanolamine 8g, small molecule chain extender neopentyl glycol 6g, amodimethicone (number average molecular weight is 1000) 8g and catalyst stannous octoate 0.05g, nitrogen protection throughout the whole process, the temperature of the oil bath is controlled at 80°C, the stirring speed is 380 rpm, and the reaction is carried out for 3 hours until -NCO reaches the theoretical value to obtain the prepolymer;

Lower the temperature in the reactor to 40°C, add 30ml of acetone to reduce the viscosity for 30 minutes, then lower the temperature to 25°C, add 2g of salt-forming agent triethylamine, react for 10 minutes, then add deionized water, at 1200 rpm Stir at a high speed under the rotating speed of 30 minutes and carry out emulsification, obtain water-based polyurethane;

Add 30 g of a mixture of methyl methacrylate and butyl acrylate (its mass ratio is 1:1) to the obtained aqueous polyurethane emulsion, and add 0.3 g of emulsifier sodium dodecyl sulfonate at the same time, and pre-swell for 14 at 25 ° C. hours (that is, mechanical stirring at room temperature for 14 hours), the stirring speed is 300 rpm, after pre-swelling for 14 hours, the reaction temperature is raised to 70 ° C, and 0.3 g of initiator potassium persulfate and 0.6 g of remaining emulsifier are added, nitrogen Under protection, stirring and reacting for 5 hours, an aqueous polyurethane-polyacrylate composite emulsion was obtained.

The obtained aqueous polyurethane-polyacrylate emulsion and coating film were tested and characterized, and the results are shown in Table 1.

Example 3

In a four-necked flask equipped with a stirring device, a condenser, a thermometer and nitrogen, add 100 g of polyoxyethylene diol (number average molecular weight: 2000), vacuumize and dehydrate at 100°C for 2 hours, and then add Isophor Ketone diisocyanate 75g, hydrophilic chain extender dimethylol butyric acid 15g, small molecule chain extender 2-methyl-1,3-propanediol 10g, dihydroxy-terminated polydimethylsiloxane (number average molecular weight 2000) 15g and catalyst dibutyltin dilaurate 0.1g, under nitrogen protection throughout the process, the temperature of the oil bath was controlled at 80°C, the stirring speed was 380 rpm, and the reaction was carried out for 3 hours until -NCO reached the theoretical value to obtain a prepolymer;

Lower the temperature in the reactor to 40°C, add 60ml of acetone to reduce the viscosity for 30 minutes, then lower the temperature to 25°C, add 4g of salt-forming agent triethylamine, react for 10 minutes, then add deionized water, at 1200 rpm Stir at a high speed under the rotating speed of 30 minutes and carry out emulsification, obtain water-based polyurethane;

Add 60 g of a mixture of methyl methacrylate and butyl acrylate (the mass ratio is 1:1) to the obtained aqueous polyurethane emulsion, and add 0.6 g of emulsifier sodium lauryl sulfate at the same time, pre-swell at 25 ° C for 14 hours (i.e. mechanical stirring at room temperature for 14 hours), the stirring speed is 300 rpm, after pre-swelling for 14 hours, the reaction temperature is raised to 70°C, and the initiator benzoyl peroxide 0.6g and the remaining emulsifier 1.2g are added , under the protection of nitrogen, stirred and reacted for 5 hours to obtain an aqueous polyurethane-polyacrylate composite emulsion.

The obtained aqueous polyurethane-polyacrylate emulsion and coating film were tested and characterized, and the results are shown in Table 1.

Example 4

In a four-necked flask equipped with a stirring device, a condenser, a thermometer and nitrogen, add 70 g of polytetrahydrofuran ether diol (number average molecular weight: 2000), vacuum dehydrate at 100 ° C for 2 hours, and then add isophor Ketone diisocyanate 50g, hydrophilic chain extender dimethylol butyric acid 9g, small molecule chain extender 1,4-butanediol 7g, hydroxyl-terminated polydimethylsiloxane (number average molecular weight: 1000) 8g and the catalyst dibutyltin dilaurate 0.1g, under nitrogen protection throughout the process, the temperature of the oil bath was controlled at 80°C, the stirring speed was 380 rpm, and the reaction was carried out for 3 hours until -NCO reached the theoretical value to obtain a prepolymer;

Lower the temperature in the reactor to 40°C, add 40ml of acetone to reduce the viscosity for 30 minutes, then lower the temperature to 25°C, add 3g of salt-forming agent triethylamine, react for 10 minutes, then add deionized water, at 1200 rpm Stir at a high speed under the rotating speed of 30 minutes and carry out emulsification, obtain water-based polyurethane;

Add 40 g of a mixture of methyl methacrylate and butyl acrylate (the mass ratio is 1:1) to the obtained aqueous polyurethane emulsion, and add 0.4 g of emulsifier sodium lauryl sulfate at the same time, pre-swell for 14 hours at 25 ° C (that is, mechanical stirring at room temperature for 14 hours), the stirring speed is 300 rpm, and after 14 hours of pre-swelling, the reaction temperature is raised to 70 ° C, and 0.4 g of initiator potassium persulfate and 0.8 g of remaining emulsifier are added. Under stirring reaction for 5 hours, water-based polyurethane-polyacrylate composite emulsion was obtained.

The obtained aqueous polyurethane-polyacrylate emulsion and coating film were tested and characterized, and the results are shown in Table 1.

Table 1

Claims (10)

1. a kind of water proof type aqueous coating polyurethane-polyacrylate emulsion, which is characterized in that the lotion is by self-emulsifying Method synthesizes Anionic Water-borne Polyurethane Emulsion, and acrylate monomer is then distributed to polyurethane by preswollen mode Polymerization obtains in system, and prepared emulsion particle is semi-IPN structures；The lotion in parts by weight, including such as Under：

。

2. a kind of water proof type aqueous coating polyurethane-polyacrylate emulsion according to claim 1, feature exist In, the polyether polyol in polyethylene glycol oxide ether glycol, polytetrahydrofuran ether glycol, polyoxypropyleneglycol one Kind is several.

3. a kind of water proof type aqueous coating polyurethane-polyacrylate emulsion according to claim 1, feature exist In it is different that the polyisocyanates monomer is selected from methyl diphenylene diisocyanate, toluene di-isocyanate(TDI), isophorone two One or more of cyanate or hexamethylene diisocyanate.

4. a kind of water proof type aqueous coating polyurethane-polyacrylate emulsion according to claim 1, feature exist In the polysiloxanes is in hydroxy-terminated polysiloxane, hydroxyalkyl terminated polysiloxane or amino-terminated polysiloxanes One or more.

5. a kind of water proof type aqueous coating polyurethane-polyacrylate emulsion according to claim 1, feature exist In the acrylic ester monomer is selected from butyl acrylate, methyl methacrylate, ethyl methacrylate or metering system One or more of acid butyl ester.

6. a kind of water proof type aqueous coating polyurethane-polyacrylate emulsion according to claim 1, feature exist It is selected from ethylene glycol, neopentyl glycol, 1,4-butanediol or 2- methyl-1s in, the small molecule chain extender, one in 3-propanediol Kind is several.

7. a kind of water proof type aqueous coating polyurethane-polyacrylate emulsion according to claim 1, feature exist In, the hydrophilic chain extender be selected from dihydromethyl propionic acid, dihydroxy half ester, ethylenediamine base ethanesulfonic acid sodium, diethylenetriamine or One or more of methyl diethanolamine.

8. a kind of water proof type aqueous coating polyurethane-polyacrylate emulsion according to claim 1, feature exist In the one kind of the salt forming agent in triethylamine, ammonium hydroxide or sodium hydroxide.

9. a kind of preparation of water proof type aqueous coating polyurethane-polyacrylate composite emulsion according to claim 1 Method, which is characterized in that include the following steps：

Step 1：Polyether polyol, polyisocyanates, polysiloxanes, small molecule chain extender, hydrophilic expansion are added in the reaction vessel Chain agent and catalyst react 2~4 hours at 75~95 DEG C, obtain prepolymer；

Step 2：Temperature in reaction vessel is down to 30~40 DEG C, acetone viscosity reduction is added, the reaction was continued 20~40 minutes, then Salt forming agent is added, reacts 5~10 minutes, deionized water stirring is added at room temperature, obtains aqueous polyurethane emulsion；

Step 3：It is added acrylic ester monomer in obtained aqueous polyurethane emulsion, pre-swollen 12~24 hours at 25 DEG C, 1/3 emulsifier is added simultaneously, after waiting for pre-swollen, reaction temperature is risen to 65~80 DEG C, initiator and remaining emulsification is added Agent, nitrogen protection are stirred to react 3~7 hours, obtain water proof type aqueous coating polyurethane-polyacrylate composite emulsion.

10. a kind of preparation of water proof type aqueous coating polyurethane-polyacrylate composite emulsion according to claim 9 Method, which is characterized in that the mixing speed of the step three is 250~300 revs/min.