CN105061665B - A kind of hydroxy polyacrylate lotion and preparation method and application - Google Patents

Abstract

The invention discloses a hydroxyl polyacrylate emulsion and its preparation method and application. The preparation method comprises weighing acrylate monomers and/or methacrylate monomers, hydroxyl acrylate monomers, acrylic acid monomers, Functional monomers, hydroxyl oligomers, mix well to prepare a monomer mixture, take 10-15% of the monomer mixture and emulsify it with an emulsifier to prepare a seed pre-emulsion for later use; add the emulsifier, sodium bicarbonate and deionized water to the reactor During the process, stir and increase the temperature of the reaction system, add the initiator, stabilize, drop the seed pre-emulsion, stabilize, drop the remaining monomer mixture and the remaining initiator, heat up, mature, cool down, and neutralize , after heat preservation, the temperature is lowered and the material is discharged to obtain a hydroxyl polyacrylate emulsion; the coating film of the water-based two-component polyurethane coating prepared by the hydroxyl polyacrylate emulsion and a water-based polyisocyanate curing agent has high hardness, high gloss and excellent chemical resistance.

Description

A kind of hydroxyl polyacrylate emulsion and its preparation method and application

technical field

The invention relates to a water-based two-component polyurethane coating, in particular to a hydroxyl polyacrylate emulsion and its preparation method and application.

Background technique

Most of the existing wood coatings are solvent-based coatings, which contain more than 50% of organic solvents. These solvents will volatilize into the atmosphere during the construction process to pollute the environment and damage human health, and the organic solvents themselves will cause combustion, explosion, etc. Security risks. Therefore, water-based wood coatings are the development trend of international coatings. Waterborne wood coatings include one-component and two-component water-based wood coatings. Among them, the paint film properties of one-component water-based wood coatings include poor water resistance, chemical resistance and hardness, which are far behind oil-based coatings, which seriously limits the popularization and application of water-based wood coatings. The mechanical properties, water resistance and chemical resistance of two-component water-based wood coatings are equivalent to those of solvent-based wood coatings, which can well overcome the shortcomings of one-component water-based wood coatings. In January 2015, my country has issued a decree on imposing consumption tax on solvent-based coatings, making two-component water-based wood coatings the first choice for high-end water-based wood coatings.

Two-component water-based polyurethane coatings have been extensively researched and applied due to their excellent coating properties. They are composed of water-based polymer polyols and water-based polyisocyanate curing agents, which are packaged separately and mixed in proportion when used. The water-based polymer polyols include water-based polyacrylate polyols, water-based polyurethane polyols, water-based polyester polyols, polyether polyols and mixed polyols. Among them, water-based polyacrylate polyols have excellent color retention, gloss retention and weather resistance, are cheap, and have the advantages of easy adjustment of molecular weight, glass transition temperature (Tg) and hydroxyl content. First choice for polymer polyols. Two types of polyacrylate polyols, emulsion type and dispersion type, can be prepared by different polymerization processes. The hydroxyl content of water-based polyacrylate dispersion is relatively high, and the prepared coating film has excellent water resistance and chemical resistance. There are a large amount of organic solvents used in the production process, and the solid content of the product is low, generally 30%-40%. And the paint film has the disadvantages of slow drying speed and high cost. In contrast, the production process of emulsion polyacrylate polyol (also called hydroxyl polyacrylate emulsion) is simple, the solid content can be as high as more than 50%, the cost is low, and the drying speed is fast. Therefore, two-component polyurethane coatings formulated with hydroxyl polyacrylate emulsions occupy a larger market space for water-based two-component coatings.

The existing paint films prepared from hydroxyl polyacrylate emulsions and water-based polyisocyanate curing agents still have problems such as poor appearance, poor chemical resistance, and low hardness. The main manifestations of the poor appearance of the paint film are poor transparency and low gloss of the paint film. The main reason is that the hydroxyl polyacrylate emulsion has poor emulsification and dispersibility of the curing agent and poor compatibility with the curing agent. When the Tg of polyacrylate designed to ensure high hardness of the paint film is high, the compatibility with the curing agent is not good, resulting in poor appearance of the paint film. The higher the crosslinking density of the paint film, the better its chemical resistance, and the polyacrylate with high hydroxyl content can obtain a paint film with high crosslinking density. However, conventional polyacrylate emulsions with high hydroxyl content have poor polymerization stability and are unstable in industrial production. In addition, excessive use of emulsifiers or improper combination of emulsifiers in emulsion polymerization will reduce the gloss and chemical resistance of the paint film. At present, the hardness and chemical resistance of waterborne two-component polyurethane paint films are improved by increasing the glass transition temperature and hydroxyl content of hydroxyl polyacrylate emulsions, which will also lead to the need for more organic small molecule film-forming aids in the process of paint formulation. Adding agent and curing agent (the curing agent often contains a certain amount of co-solvent), increasing the content of volatile organic compounds (VOC) in the coating will also lead to an increase in the cost of the coating. Therefore, it is difficult to improve the problems of poor appearance, poor chemical resistance, and low hardness of the hydroxyl polyacrylate emulsion type two-component paint film by conventional methods.

Chinese invention patent application CN103059210 modifies the hydroxyl polyacrylate emulsion by adding 2%-5% fluorine-containing acrylic acid monomer, although the water resistance and chemical resistance of the two-component paint film will be slightly improved, due to the fluorine-containing acrylic acid The hydrophobic and oleophobic properties of the ester monomer make the conversion rate of the polymerization reaction not high, which easily causes a large amount of fluorine-containing monomers to remain, and also causes problems such as poor interlayer adhesion of the paint film, and the fluorine-containing acrylate monomer The high price has caused the cost of polymer emulsion to rise sharply.

Contents of the invention

The purpose of the present invention is to overcome the problems existing in the prior art, to provide an easy adjustment of the hydroxyl content of the hydroxyl polyacrylate emulsion, so that multiple hydroxyl resins with different structures, different molecular weights, and different glass transition temperatures can form multiple intersections with curing agents. Linked hydroxyl polyacrylate emulsion and preparation method thereof.

Another object of the present invention is to provide the application of the hydroxyl polyacrylate emulsion in the water-based two-component polyurethane coating, so that the coating film hardness of the two-component polyurethane coating reaches H, and the gloss (60 °) reaches 83%, which has excellent Water/alcohol resistance, also has good dry heat resistance.

The present invention aims at the deficiencies of the prior art, and adopts the process of adding oligomers with high hydroxyl content in the emulsion polymerization process of hydroxyl polyacrylate to prepare hydroxyl polyacrylate emulsion with appropriate hydroxyl content. This process not only realizes the production of hydroxyl polyacrylate emulsion The content of hydroxyl groups is easy to adjust, and multiple hydroxyl resins with different structures, different molecular weights, and different Tgs can form multiple cross-linked structures with curing agents. Compared with the conventional emulsion with the same hydroxyl content without the addition of hydroxyl oligomers, it greatly improves the appearance of the paint film, increases the hardness of the paint film, and solves the problems of poor chemical resistance. At the same time, under the premise of ensuring the stability of emulsion polymerization and high monomer conversion rate, the adjustable range of the hydroxyl content of the hydroxyl polyacrylate emulsion of the present invention is wider, so that the hydroxyl polyacrylate emulsion with high hydroxyl content is easy to realize large-scale industrialization Production. In addition, the present invention uses a special acrylic monomer, such as isobornyl (meth)acrylate, to improve the compatibility between the hydroxyl polyacrylate emulsion and the curing agent, thereby improving the appearance of the paint film.

Realize the technical scheme that the object of the present invention adopts:

The preparation method of hydroxyl polyacrylate emulsion comprises the steps:

In terms of parts by mass, weigh 30-45 parts of acrylate monomers and/or methacrylate monomers, 5-15 parts of hydroxyacrylate monomers, 1.0-3.0 parts of acrylic monomers, and 0.5 parts of acrylate functional monomers. ～3.0 parts, 0.5～3 parts of hydroxyl oligomers, mix uniformly to prepare monomer mixture, take 10-15% of monomer mixture and emulsify with 1-2 parts of emulsifier to prepare seed pre-emulsion for later use;

Add 1-2 parts of emulsifier, 0.05-0.2 parts of sodium bicarbonate and 20-30 parts of deionized water into the reaction kettle, start stirring and increase the temperature of the reaction system. When the temperature reaches 78-83°C, add 10-15 % initiator, after 5-15 minutes of stability, drop the seed pre-emulsion within 15-30 minutes, stabilize for 15-30 minutes, dissolve the remaining monomer mixture and 10-20 parts of water to dissolve the remaining initiator in Dropping is completed within 3-4 hours, heat up to 80-85°C and mature for 1-2 hours, cool down to 40-60°C, dilute 0.3-0.6 parts of neutralizer with 3-10 parts of water for neutralization, keep warm for 15-30 minutes Cooling and discharging to obtain hydroxyl polyacrylate emulsion;

The hydroxy acrylate monomer is one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate;

The hydroxy acrylate monomer is one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

The acrylic acid monomer is one or more of acrylic acid and methacrylic acid.

The acrylate functional monomer is one or more of acrylamide, isobornyl methacrylate, glycidyl methacrylate, and acetoacetoxyethyl methacrylate.

Described hydroxyl oligomer is the aldehyde resin A81 of BASF company, the aldehyde ketone resin KR-80F, KR-120, KR120B, KR-120W of Changsha Changtai Industrial Co., Ltd., the UK-100, One or more of UK-300, UK-500, YHKR-1210 and YHKR-1218 of Baling Petrochemical Aldehyde Resin.

Described emulsifying agent is the ADEKA REASOAP series non-ionic (ER-30) and anionic (SR-10) emulsifying agent of isomeric alcohol polyoxyethylene ether (EH-9), Aidike Company, 2-acrylamide group-2 - One or more of sodium methylpropanesulfonate (COPS-2), fatty alcohol polyoxyethylene ether ammonium sulfate (KL-525), sodium dodecyl sulfate (SDS).

The initiator is one or more of potassium persulfate and ammonium persulfate.

A hydroxyl polyacrylate emulsion prepared by the above preparation method. The particle size of the obtained hydroxyl polyacrylate emulsion is less than 300nm, the solid content is 45-52%, the hydroxyl value is 40-150mgKOH/g, and the Tg is 10-80°C.

The hydroxyl polyacrylate emulsion of the present invention is mainly used in the preparation of water-based two-component polyurethane coatings.

Add the hydroxyl polyacrylate emulsion into the stirring tank, add 1-10 parts of film-forming aids, 0.05-1.5 parts of defoamers, 0.05-0.2 parts of thickeners, 0.05-0.3 parts of wetting agent and 0.05-0.1 part of neutralizer, disperse for 10-30 minutes, filter the material, the coating prepared by hydroxyl polyacrylate emulsion;

The film-forming aid is one or more of propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, and dipropylene glycol butyl ether.

The defoamer is polyether siloxane copolymer defoamer TEGO-800, TEGO-805, TEGO-815, TEGO-825 of TEGO Company and modified polysiloxane copolymer solution BYK-019 of BYK Company , one or more of BYK-020.

The thickener is DOW's non-ionic polyurethane associative thickener RM-8W, hydrophobically modified alkali-swellable associative thickener TT-935, alkali-swellable non-associative thickener ASE-60 and One or more of TEGO ViscoPlus 3000, TEGO ViscoPlus 3030, and TEGO ViscoPlus 3060 non-ionic associative thickeners from TEGO.

The wetting agent is one or more of the polyether siloxane copolymer TEGO-245 of TEGO Company, the nonionic organic surfactant TEGO-500 and the polyether modified polysiloxane solution BYK-346 of BYK Company. kind.

Said neutralizing agent is one or more of triethylamine and dimethylethanolamine.

The polyisocyanate curing agent includes one or more of sulfonate, carboxylate and alkoxy-modified hexamethylene diisocyanate (HDI).

The obtained waterborne two-component polyurethane coating film has the advantages of high gloss, high transparency, excellent water resistance and chemical resistance, high crosslinking density, high hardness, scratch resistance and wear resistance, and the like. It can be applied to high-grade wood coatings, automotive coatings, metal anti-corrosion coatings and other industrial protective coatings.

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

The chemical resistance of the waterborne two-component polyurethane coating film is determined by the crosslinking density of the coating film, which is regulated by the OH group content of the hydroxyl polyacrylate emulsion and the molar ratio of NCO to OH; the appearance and decorative properties of the coating film are determined by the phase between components. It is determined by the compatibility, and the compatibility is related to the structure of the water-based hydroxyl resin, the particle structure and shape, the emulsifying ability of the curing agent and the content of the emulsifier. The hydroxyl polyacrylate emulsion of the present invention uses polyacrylate polyol as the main hydroxyl component, and hydroxyl oligomers as the auxiliary hydroxyl component. First, dissolve an appropriate amount of hydroxy oligomer with a monomer mixture, pre-emulsify it with an appropriate amount of emulsifier, take part or all of the pre-emulsion to prepare seeds, and use the process of pre-emulsification seed emulsion polymerization to prepare hydroxyl polyacrylate lotion. The present invention avoids the problem of sharp decrease in polymerization stability caused by excessive addition of hydroxy acrylate monomers. Therefore, by adjusting the type and amount of hydroxyl oligomers, the hydroxyl value of the emulsion can be greatly increased and the hydroxyl structure can be adjusted, thereby improving the stability of the polymer. Mechanical and chemical properties of component coating films. At the same time, the introduced hydroxyl oligomer itself has the characteristics of high gloss and high transparency, which can further improve the appearance and decorative properties of the coating film. The coating film of the water-based two-component polyurethane coating prepared by the hydroxyl polyacrylate emulsion and the water-based polyisocyanate curing agent of the present invention has high hardness, high gloss and excellent chemical resistance, and solves the problems caused by the hydroxyl value of the traditional hydroxyl polyacrylate emulsion. The problem of poor mechanical and chemical properties of the paint film caused by low carbon dioxide content has overcome the problems of low gloss and poor transparency of the paint film prepared with water-based polyisocyanate curing agent.

specific embodiment

The present invention will be further described below in conjunction with specific examples, but the embodiments of the present invention are not limited thereto, and for the process parameters not specified in particular, it can be carried out with reference to conventional techniques.

The relevant detection method of following embodiment is as follows:

The basic performance test includes: the hydroxyl polyacrylate emulsion is tested according to GB/T11175-2002 "Test Method for Synthetic Resin Emulsion", and the appearance, pH, solid content and viscosity of the emulsion are tested. The performance of the paint film is tested with reference to GB/T23999-2009 "Water-based Wood Coatings for Interior Decoration" to test gloss, hardness, water resistance, dry heat resistance, and alcohol resistance. The average particle size of the emulsion was measured by a nanometer particle size analyzer (ZS Nano S).

Example 1

(1) Preparation of hydroxyl polyacrylate emulsion: the formula of hydroxyl polyacrylate emulsion (hydroxyl value=65mgKOH/g) is shown in Table 1a:

Table 1a

Preparation process: Mix 1-9 to prepare monomer mixture, take 10% monomer mixture and pre-emulsify it with 0.05 parts of emulsifier (including 0.025 parts of KL-525 and 0.025 parts of COPS-2) and 2.75 parts of water as seed pre-emulsification liquid. Add the remaining emulsifier, sodium bicarbonate, 0.1 part of initiator (potassium persulfate), and 25 parts of deionized water into the reaction kettle, raise the temperature to 78°C, stir for 15 minutes, and drip the seed pre-emulsion within 20 minutes at a constant speed , and wait for the emulsion to be stable for half an hour to obtain the seed emulsion. Keep the temperature of the reaction system at 80°C. Mix the remaining mixed monomers with the rest of the monomers, then add dropwise to the seed emulsion, and at the same time add dropwise an aqueous solution of 0.15 parts of initiator (potassium persulfate) dissolved in 15 parts of water, and finish dropping in about 3.5 hours. After the dropwise addition, the temperature was raised to 85°C and kept for 1.5h. Cool down to 55°C, mix 5.5 parts of water and neutralizing agent triethylamine, add to neutralize, keep warm for 0.25h, cool down and discharge to obtain milky white and semi-transparent hydroxyl polyacrylate emulsion.

(2) Properties of the hydroxyl polyacrylate emulsion: the prepared emulsion has an average particle diameter of 128nm, a viscosity of 535cps, pH=7.0, and a solid content of 48.3%.

(3) Preparation of high-performance water-based two-component polyurethane coatings: the formula is shown in Table 1b:

Table 1b

The molar ratio of the NCO group in the curing agent to the OH group in the hydroxyl polyacrylate emulsion is 1.8:1.

The preparation method is as follows: put the emulsion into a stirring tank at a speed of 700 rpm, pre-mix 10 parts of water and film-forming aids and add it to the emulsion, add raw materials No. 5-9 in sequence, disperse for 20 minutes, and filter out the material . During construction, the water-based polyisocyanate curing agent is added to the coating prepared from the above-mentioned hydroxyl polyacrylate emulsion, and stirred for 6 minutes to obtain a water-based two-component polyurethane coating.

(4) Coating film performance: The film prepared by water-based two-component polyurethane coating is cured and dried at room temperature for 7 days, and its properties are as follows:

Table 1c Comprehensive properties of high-performance waterborne two-component polyurethane coatings

In this example, the hydroxyl oligomer A81 is added to the hydroxyl polyacrylate emulsion with a relatively low hydroxyl content, and the monomer is dissolved and pre-emulsified to prepare an emulsified seed emulsion, and the hydroxyl polyacrylate emulsion is prepared on the basis of the seed emulsion. This method ensures that the hydroxyl oligomer is stably dispersed in the hydroxyl polyacrylate emulsion, mainly existing in the interior of the latex particles, and the acrylate monomer is polymerized in the hydroxyl oligomer to form an interpenetrating polymer of polyacrylate and hydroxyl oligomer The network, on the one hand, ensures that the hydroxyl oligomer and the acrylic polymer are fully mixed, and on the other hand, there may be a small amount of acrylic polymer grafted to the hydroxyl oligomer, and the grafted polymer provides a polymer-compatible bridge. The addition of hydroxyl oligomers increases the hydroxyl content of the hydroxyl polyacrylate emulsion, ensures the polymerization stability of the hydroxyl polyacrylate emulsion, makes the hardness of the two-component coating film reach H, and the gloss (60°) is 83%. Excellent water/ethanol resistance and good dry heat resistance. The hydroxyl polyacrylate emulsion prepared by this method overcomes the shortcomings of the traditional hydroxyl polyacrylate emulsion for preparing two-component polyurethane coatings.

Example 2

(1) Preparation of hydroxyl polyacrylate emulsion: the formula of hydroxyl polyacrylate emulsion (hydroxyl value=65mgKOH/g) is shown in Table 2a:

Table 2a

Preparation method: Mix 1-8 to prepare monomer mixture, take 15% of monomer mixture and dissolve it with 0.1 part of emulsifier (0.05 parts of SR-10 and ER-30) and 3 parts of water to pre-emulsify it as seed pre-emulsification liquid. Add the remaining emulsifier, sodium bicarbonate, 0.1 part of initiator (ammonium persulfate), and 30 parts of deionized water into the reaction kettle, raise the temperature to 80°C, stir for 30 minutes, and drip the seed pre-emulsion within 30 minutes at a constant speed , and wait for the emulsion to be stable for half an hour to obtain the seed emulsion. Keep the temperature of the reaction system at 80°C. Add the remaining monomer mixture dropwise to the seed emulsion, and at the same time add dropwise an aqueous solution in which 0.2 parts of the initiator (ammonium persulfate) is dissolved in 20 parts of water, and the drop is completed in about 4 hours. After the dropwise addition, the temperature was raised to 82° C. and kept for 2 hours. Cool down to 45°C, mix 10 parts of water and N,N-dimethylethanolamine, add to neutralize, keep warm for 0.25h, cool down and discharge to obtain milky white and semi-transparent hydroxyl polyacrylate emulsion.

(2) Properties of the hydroxyl polyacrylate emulsion: the prepared emulsion has an average particle diameter of 135 nm, a viscosity of 573 cps, pH=7.0, and a solid content of 48.5%.

(3) Preparation of high-performance water-based two-component polyurethane coatings: the formula is shown in Table 2b:

Table 2b

The molar ratio of the NCO group in the curing agent to the OH group in the hydroxyl polyacrylate emulsion is 1.5:1.

The preparation method is as follows: put the emulsion into a stirring tank at a speed of 700 rpm, pre-mix 10 parts of water and film-forming aids and add it to the emulsion, add raw materials No. 5-9 in sequence, disperse for 10 minutes, and filter out the material . During construction, the water-based polyisocyanate curing agent is added to the coating prepared from the above-mentioned hydroxyl polyacrylate emulsion, and stirred for 5 minutes to obtain a water-based two-component polyurethane coating.

(4) Two-component coating properties: The paint film made of water-based two-component polyurethane coatings is cured and dried at room temperature for 7 days, and its properties are as follows:

Table 2c Comprehensive properties of high-performance waterborne two-component polyurethane coatings

Example 3

(1) Preparation of hydroxyl polyacrylate emulsion: the formula of hydroxyl polyacrylate emulsion (hydroxyl value=70mgKOH/g) is shown in Table 3a:

Table 3a

Preparation process: Mix 1-8 to prepare a monomer mixture, take 12% monomer mixture and pre-emulsify it with 0.1 part of emulsifier (0.05 parts of each of the two emulsifiers) and 3 parts of water as a seed pre-emulsion. Add the remaining emulsifier, sodium bicarbonate, 0.1 part of initiator (KPS), and 20 parts of deionized water into the reaction kettle, raise the temperature to 82°C, stir for 15 minutes, and drip the seed pre-emulsion at a constant speed within 15 minutes. The emulsion was stable for half an hour to obtain a seed emulsion. The temperature of the reaction system was kept at 82°C. Mix the remaining monomer mixture with the rest of the monomers, then add dropwise to the seed emulsion, and at the same time add dropwise an aqueous solution of 0.2 parts of initiator (KPS) dissolved in 10 parts of water, and drop it in about 3 hours. After the dropwise addition, the temperature was raised to 85° C. and kept for 1 h. Cool down to 60°C, mix 5.9 parts of water and triethylamine, add to neutralize, keep warm for 30 minutes, cool down and discharge to obtain milky white and semi-transparent hydroxyl polyacrylate emulsion.

(2) Properties of the hydroxyl polyacrylate emulsion: the prepared emulsion has an average particle diameter of 123nm, a viscosity of 617cps, pH=7.0, and a solid content of 48.0%.

(3) Preparation of high-performance water-based two-component polyurethane coating: the formula is shown in Table 3b:

Table 3b

The molar ratio of the NCO group in the curing agent to the OH group in the hydroxyl polyacrylate emulsion is 1.2:1.

The preparation method is as follows: put the emulsion into a stirring tank at a speed of 700 rpm, pre-mix 10 parts of water and film-forming aids and add it to the emulsion, add raw materials No. 5-9 in sequence, disperse for 10 minutes, and filter out the material . During construction, the water-based polyisocyanate curing agent is added to the coating prepared from the above-mentioned hydroxyl polyacrylate emulsion, and stirred for 8 minutes to obtain a water-based two-component polyurethane coating.

(4) The paint film properties of the water-based two-component polyurethane coating: the prepared paint film was solidified and dried at room temperature for 7 days, and its properties were as follows:

Table 3c Comprehensive properties of high-performance waterborne two-component polyurethane coatings

Example 4

(1) Preparation of hydroxyl polyacrylate emulsion: the formula of hydroxyl polyacrylate emulsion (hydroxyl value=79mgKOH/g) is shown in Table 4a:

Table 4a

Preparation process: Mix 1-8 uniformly to prepare a monomer mixture, take 14 parts of the monomer mixture and pre-emulsify it with 0.1 part of emulsifier (0.05 parts of each of the two emulsifiers) and 3.35 parts of water as a seed pre-emulsion. Add the remaining emulsifier, sodium bicarbonate, 0.1 part of initiator, and 25 parts of deionized water into the reaction kettle, raise the temperature to 75°C, stir for 15 minutes, drop the seed pre-emulsion at a constant speed within 20 minutes, and wait until the emulsion is half-stabilized hours, to obtain seed emulsion. Keep the temperature of the reaction system at 80°C. Add the remaining monomer mixture dropwise to the seed emulsion, and at the same time add dropwise an aqueous solution in which 0.2 parts of the initiator is dissolved in 15 parts of water, and the drop is completed in about 3.5 hours. After the dropwise addition, the temperature was raised to 85°C and kept for 1.5h. Cool down to 55°C, mix 6 parts of water and N,N-dimethylethanolamine, add to neutralize, keep warm for 0.25h, cool down and discharge to obtain milky white and semi-transparent hydroxyl polyacrylate emulsion.

(2) Properties of the hydroxyl polyacrylate emulsion: the prepared emulsion has an average particle diameter of 119 nm, a viscosity of 820 cps, pH=7.0, and a solid content of 47.7%.

(3) Preparation of high-performance water-based two-component polyurethane coatings: the formula is shown in Table 4b:

Table 4b

The molar ratio of the NCO group in the curing agent to the OH group in the hydroxyl polyacrylate emulsion is 1.8:1.

The preparation method is as follows: add the emulsion into a stirring tank at a speed of 700 rpm, pre-mix 10 parts of water and film-forming aids and add it to the emulsion, add raw materials No. 5-9 in sequence, disperse for 25 minutes, and filter out the material . During construction, the water-based polyisocyanate curing agent is added to the coating prepared from the above-mentioned hydroxyl polyacrylate emulsion, and stirred for 7 minutes to obtain a water-based two-component polyurethane coating.

(4) Coating properties of water-based two-component polyurethane coatings: The coating film prepared by water-based two-component polyurethane coatings is cured and dried at room temperature for 7 days, and its properties are as follows:

Table 4c Comprehensive properties of high-performance water-based two-component polyurethane coatings

Example 5

(1) Preparation of hydroxyl polyacrylate emulsion: the formula of hydroxyl polyacrylate emulsion (hydroxyl value=95mgKOH/g) is shown in Table 5a:

Table 5a

Preparation process: Mix 1-7 evenly to prepare monomer mixture, take 13 parts of monomer mixture and pre-emulsify it with 0.1 part of emulsifier (0.05 parts of each of the two emulsifiers) and 4 parts of water as seed pre-emulsion. Add the remaining emulsifier, sodium bicarbonate, 0.1 part of initiator, and 25 parts of deionized water into the reaction kettle, raise the temperature to 75°C, stir for 15 minutes, and drop the seed pre-emulsion at a constant speed within 20 minutes, and wait until the emulsion is half-stabilized hours, to obtain seed emulsion. Keep the temperature of the reaction system at 80°C. Add the remaining monomer mixture dropwise to the seed emulsion, and at the same time add dropwise an aqueous solution in which 0.2 parts of the initiator is dissolved in 15 parts of water, and the drop is completed in about 3.5 hours. After the dropwise addition, the temperature was raised to 85°C and kept for 1.5h. Cool down to 55°C, mix 5.9 parts of water and triethylamine, add to neutralize, keep warm for 0.25h, cool down and discharge to obtain milky white and semi-transparent hydroxyl polyacrylate emulsion.

(2) Properties of the hydroxyl polyacrylate emulsion: the prepared emulsion has an average particle diameter of 132nm, a viscosity of 673cps, pH=7.0, and a solid content of 48.2%.

(3) Preparation of high-performance water-based two-component polyurethane coating: the formula is as shown in Table 5b:

Table 5b

The molar ratio of the NCO group in the curing agent to the OH group in the hydroxyl polyacrylate emulsion is 1.5:1.

The preparation method is as follows: put the emulsion into a stirring tank at a speed of 700 rpm, pre-mix 10 parts of water and film-forming aids, add it to the emulsion, add raw materials No. 5-9 in sequence, disperse for 30 minutes, and filter out the material . During construction, the water-based polyisocyanate curing agent is added to the coating prepared from the above-mentioned hydroxyl polyacrylate emulsion, and stirred for 6 minutes to obtain a water-based two-component polyurethane coating.

(4) Coating properties of water-based two-component polyurethane coatings: The coating film prepared by water-based two-component polyurethane coatings is cured and dried at room temperature for 7 days, and its properties are as follows:

Table 5c Comprehensive properties of high-performance waterborne two-component polyurethane coatings

Example 6

(1) Preparation of hydroxyl polyacrylate emulsion: the formula of hydroxyl polyacrylate emulsion (hydroxyl value=110mgKOH/g) is shown in Table 6a:

Table 6a

Preparation process: Mix 1-7 uniformly to prepare a monomer mixture, take 10% of the monomer mixture and pre-emulsify it with 0.1 part of emulsifier (0.05 parts of each of the two emulsifiers) and 4.5 parts of water as the seed pre-emulsion. Add the remaining emulsifier, sodium bicarbonate, 0.1 part of initiator, and 25 parts of deionized water into the reaction kettle, raise the temperature to 75°C, stir for 15 minutes, and drop the seed pre-emulsion at a constant speed within 20 minutes, and wait until the emulsion is half-stabilized hours, to obtain seed emulsion. Keep the temperature of the reaction system at 80°C. Add the remaining monomer mixed mixture dropwise to the seed emulsion, and at the same time add dropwise an aqueous solution in which 0.2 parts of the initiator is dissolved in 15 parts of water, and the drop is completed in about 3.5 hours. After the dropwise addition, the temperature was raised to 85°C and kept for 1.5h. Cool down to 55°C, mix 5.55 parts of water and N,N-dimethylethanolamine, add to neutralize, keep warm for 0.25h, cool down and discharge to obtain milky white and semi-transparent hydroxyl polyacrylate emulsion.

(2) Properties of the hydroxyl polyacrylate emulsion: the prepared emulsion has an average particle diameter of 125nm, a viscosity of 725cps, pH=7.0, and a solid content of 47.6%.

(3) Preparation of high-performance water-based two-component polyurethane coating: the formula is as shown in Table 6b:

Table 6b

The molar ratio of the NCO group in the curing agent to the OH group in the hydroxyl polyacrylate emulsion is 1.0:1.

The preparation method is as follows: put the emulsion into a stirring tank at a speed of 700 rpm, pre-mix 10 parts of water and film-forming aids and add it to the emulsion, add raw materials No. 5-9 in sequence, disperse for 20 minutes, and filter out the material . During construction, the water-based polyisocyanate curing agent is added to the coating prepared from the above-mentioned hydroxyl polyacrylate emulsion, and stirred for 5 minutes to obtain a water-based two-component polyurethane coating.

(4) Coating properties of water-based two-component polyurethane coatings: The coating film prepared by water-based two-component polyurethane coatings is cured and dried at room temperature for 7 days, and its properties are as follows:

Table 6c Comprehensive properties of high-performance waterborne two-component polyurethane coatings

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (8)

1. a preparation method of hydroxyl polyacrylate emulsion, it is characterized in that comprising the following steps, 1) In parts by mass, weigh 30 to 45 parts of acrylate monomer and/or methacrylate monomer, 5 to 15 parts of hydroxyacrylate monomer, 1.0 to 3.0 parts of acrylic monomer, acrylate functional unit 0.5-3.0 parts of monomer, 0.5-3 parts of hydroxy oligomer, mix well to prepare monomer mixture, take 10-15% of monomer mixture and emulsify with 1-2 parts of emulsifier to prepare seed pre-emulsion for later use; 2) In parts by mass, add 1-2 parts of emulsifier, 0.05-0.2 parts of sodium bicarbonate and 20-30 parts of deionized water into the reaction kettle, start stirring and increase the temperature of the reaction system. When the temperature reaches 78 Add 10-15% initiator after -83°C, stabilize for 5-15 minutes, add the seed pre-emulsion dropwise within 15-30 minutes, stabilize for 15-30 minutes, mix the remaining monomer mixture with 10-20 Dissolve the remaining initiator in 3-4 hours and drop it in 3-4 hours, heat up to 80-85°C and mature for 1-2 hours, cool down to 40-60°C, dilute 0.3-0.6 parts of neutralizer with 3-10 parts of water And, cooling and discharging after 15-30 minutes of heat preservation to obtain a hydroxyl polyacrylate emulsion; The acrylate monomer and/or methacrylate monomer is one or more of methyl methacrylate, methyl acrylate, ethyl acrylate, butyl methacrylate and butyl acrylate; The hydroxy acrylate monomer is one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate; The acrylic acid monomer is acrylic acid and/or methacrylic acid; The acrylate functional monomer is one or more of isobornyl methacrylate, glycidyl methacrylate and acetoacetoxyethyl methacrylate; The hydroxy oligomer is aldehyde resin A81, aldehyde and ketone resin KR-80F, KR-120, KR120B, KR-120W, aldehyde and ketone resin UK-100, UK-300, UK-500, aldehyde and ketone resin YHKR-1210 and One or more of YHKR-1218; The emulsifier is isomerized alcohol polyoxyethylene ether, polymerizable emulsifier ADEKAREASOAP series non-ionic ER-30 and anionic SR-10 emulsifier, 2-acrylamide-2-methylpropanesulfonate sodium, fatty alcohol poly One or more of ammonium oxyethylene ether sulfate and sodium lauryl sulfate; The initiator is one or more of potassium persulfate and ammonium persulfate. 2. the preparation method of hydroxyl polyacrylate emulsion according to claim 1 is characterized in that, described neutralizing agent is one or more in triethylamine, ammoniacal liquor and dimethylethanolamine. 3. The preparation method of the hydroxyl polyacrylate emulsion according to claim 1, characterized in that, in terms of solid resin, the hydroxyl value of the hydroxyl polyacrylate emulsion is 40-150 mgKOH/g. 4. The preparation method of the hydroxyl polyacrylate emulsion according to claim 1, characterized in that, the glass transition temperature of the hydroxyl polyacrylate emulsion is 10-80°C. 5. A hydroxyl polyacrylate emulsion, which is characterized in that it is prepared by the preparation method described in any one of claims 1-4. 6. the application of the hydroxyl polyacrylate emulsion described in claim 5 in water-based two-component polyurethane coatings. 7. according to the application of the described hydroxyl polyacrylate emulsion of claim 6 in waterborne two-component polyurethane coating, it is characterized in that comprising the steps: 1) Add the hydroxyl polyacrylate emulsion into the stirring tank, and add 1-10 parts of film-forming aids, 0.05-1.5 parts of defoamers, 0.05-0.2 parts of thickeners, 0.05-0.3 parts of Wetting agent and 0.05-0.1 part of neutralizing agent, dispersed for 10-30 minutes, filtered and discharged to obtain a coating prepared from hydroxyl polyacrylate emulsion; 2) During construction, the water-based polyisocyanate curing agent is added to the coating prepared from the hydroxyl polyacrylate emulsion according to the NCO/OH molar ratio of 1.0-1.8, and stirred for 5-8 minutes to obtain a water-based two-component polyurethane coating. 8. according to the application of the described hydroxyl polyacrylate emulsion of claim 7 in waterborne two-component polyurethane coatings, it is characterized in that, described film-forming aid is propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether and dipropylene glycol One or more of butyl ethers; The defoamer is one of polyether siloxane copolymer defoamer TEGO-800, TEGO-805, TEGO-815, TEGO-825, modified polysiloxane copolymer solution BYK-019 and BYK-020 one or more kinds; The thickener is non-ionic polyurethane associative thickener RM-8W, hydrophobically modified alkali-swellable associative thickener TT-935, alkali-swellable non-associative thickener ASE-60, non-ionic associative thickener One or more of TEGO ViscoPlus 3000, TEGO ViscoPlus 3030 and TEGO ViscoPlus 3060 thickeners; The wetting agent is one or more of polyether siloxane copolymer TEGO-245, nonionic organic surfactant TEGO-500 and polyether modified polysiloxane solution BYK-346; Described neutralizing agent is one or more in triethylamine, ammoniacal liquor and dimethylethanolamine; The polyisocyanate curing agent includes one or more of sulfonate, carboxylate and alkoxy-hydrophilized hexamethylene diisocyanate.