CN115894809A - Core-shell emulsion, preparation method, application - Google Patents

Abstract

The invention relates to the technical field of water-based paint, and discloses a core-shell emulsion, a preparation method and application thereof; a core-shell emulsion comprises the following raw materials: the unsaturated rosin-based polyurethane containing silicon as the shell layer and the acrylic monomer as the core layer are used as initiators to initiate the cross-linking bonding between the shell layer and the core layer and the self-crosslinking of the acrylic monomer in the core layer structure, and the acrylic double bond of the core layer is bonded with the double bond of the unsaturated rosin-based polyurethane emulsion containing silicon. The product is reacted in an emulsion polymerization mode, has no VOC, no toxic and harmful solvent, and is low-carbon and environment-friendly. The single-component emulsion has the performances of an acrylic acid system and a polyurethane system, has excellent corrosion resistance, hardness and adhesive force, and can be widely applied to the fields of high-speed rails, automobiles, ships, war industry, electronics, electrical appliances, buildings, mechanical facility equipment, petrochemical industry and the like.

Description

Core-shell emulsion, preparation method, application

technical field

The invention relates to the technical field of water-based coatings, in particular to core-shell emulsions, preparation methods and applications.

Background technique

Rosin is an abundant forest resource in my country. It has excellent characteristics such as natural regeneration and biodegradability. Its main component is rosin resin acid with tricyclic diterpene structure and two types of active genes (carbon-carbon double bond and carboxyl group).

Traditional acrylic modified rosin resins can be used for both thermoplastic resins and solvent-based coatings, and are widely used in the coating field. However, most of the traditional acrylic modified rosin resins are solvent-based, and there are too many toxic and harmful solvents, so they have been largely eliminated in recent years. Although a dispersion series has been developed in recent years, the VOC is still too high, and because of the TG value, it is hot-sticky and brittle, has poor solvent resistance and chemical resistance, and has poor flexibility, poor impact resistance, and poor adhesion. Especially in technical fields that require relatively high paint films, traditional polyurethane emulsions have poor self-thickening properties, low solid content, and poor water resistance and anti-corrosion properties of latex films. .

In order to overcome these defects, two-component composite coatings are often used to meet industrial requirements. However, this two-component composite coating mode has complex procedures, cumbersome procedures, and high cost. However, traditional polyurethane-modified acrylic dispersions often cannot be used as a single component because of insufficient modification degree or too small molecular weight, or cannot reflect the excellent performance of the two systems as a single component.

Contents of the invention

<Technical Problems Solved by the Invention>

In order to solve the problems of high VOC, poor water resistance and anti-corrosion performance in the modified rosin resin existing in the prior art, the present application uses polyurethane to modify the rosin resin first, and then uses the resin as a hydrophilic emulsifier, and acrylic acid monomer reaction, a one-component self-drying coating resin combining acrylic modified rosin resin and polyurethane resin is obtained, and zero VOC is realized at the same time.

<Technical solution adopted in the present invention>

In view of the above-mentioned technical problems, the object of the present invention is to provide a core-shell emulsion, a preparation method, and an application.

First, the invention provides a core-shell emulsion, the raw materials of which include:

Silicone-containing unsaturated rosin-based polyurethane emulsion as shell layer,

Acrylic monomer as the core layer,

The initiator is used for initiating the cross-linking and bonding of the shell layer and the core layer and the self-crosslinking of the acrylic acid monomer of the core layer structure, and the acrylic acid double bond of the core layer is bonded with the double bond of the silicon-containing unsaturated rosin-based polyurethane emulsion.

Second, the present invention provides a method for preparing the aforementioned core-shell emulsion, comprising the following steps:

S1 dispersing the first part of silicon-containing unsaturated polyurethane rosin emulsion, acrylic monomer, and water to obtain a pre-emulsion;

Add water and the second part of silicon-containing unsaturated polyurethane rosin emulsion to the S2 primer reaction kettle, then add the pre-emulsion dropwise to the primer reaction kettle, and add the initiator dropwise at the same time, after dripping, heat preservation reaction;

S3 cools down, then adds a redox initiator, and neutralizes to obtain a core-shell emulsion.

Thirdly, the present invention provides an application of the aforementioned core-shell emulsion in water-based paint.

The specific content is as follows:

<Technical mechanism and beneficial effect of the present invention>

This application uses the core-shell reaction, and the polyurethane macromolecular emulsifier (containing silicon-containing unsaturated rosin-based polyurethane emulsion) in the early stage of polymerization wraps the acrylic monomer, and under the action of the initiator, the core core crosslinking is formed inside to form a core structure, and the polyurethane macromolecule The shell is formed on the outside under the action of the initiator, and at the same time, the double bond of the acrylic monomer and the double bond of the unsaturated rosin-based polyurethane resin on a part of the core structure undergo free radical crosslinking to form a latex interpenetrating network structure to ensure its transparency and stability. . In this way, a uniform latex particle with acrylic monomer as the core, silicon-containing unsaturated rosin-based polyurethane as the shell and a core-shell interpenetrating network structure is formed, thereby preparing a silicon-containing polyurethane modified acrylic emulsion.

This product reacts through emulsion polymerization, no VOC, no toxic and harmful solvents, low carbon and environmental protection.

This one-component emulsion has the properties of both acrylic system and polyurethane system, and has excellent resistance, hardness and adhesion. It can be widely used in high-speed rail, automobiles, ships, military industry, electronics, electrical appliances, construction, machinery manufacturing, petrochemical industry, etc. field.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased from the market.

First, the invention provides a core-shell emulsion, the raw materials of which include:

Silicone-containing unsaturated rosin-based polyurethane emulsion as shell layer,

Acrylic monomer as the core layer,

The initiator is used for initiating the cross-linking and bonding of the shell layer and the core layer and the self-crosslinking of the acrylic acid monomer of the core layer structure, and the acrylic acid double bond of the core layer is bonded with the double bond of the silicon-containing unsaturated rosin-based polyurethane emulsion.

Among the present invention, the preparation method of described silicon-containing unsaturated rosin-based polyurethane emulsion comprises the following steps:

In the presence of a reaction solvent, rosin, maleic anhydride, and polyols are reacted to obtain an unsaturated rosin resin;

Unsaturated rosin resin reacts with diisocyanate to obtain unsaturated rosin-based polyurethane resin;

Adding an end-capping agent to the unsaturated rosin-based polyurethane resin to obtain the silicon-containing unsaturated rosin-based polyurethane resin, and then neutralizing and adding water to disperse to obtain the silicon-containing unsaturated rosin-based polyurethane emulsion.

In the present invention, the raw materials of silicon-containing unsaturated rosin-based polyurethane emulsion are calculated in parts by weight, 12-25 parts of rosin, 2-8 parts of maleic anhydride, 5-18 parts of polyol, 5-18 parts of reaction solvent, end-capping agent 0.5-5 parts, 12-25 parts of water, 7-18 parts of diisocyanate.

In the present invention, the polyhydric alcohol includes at least one of pentaerythritol, trimethylolpropane, and glycerin.

In the present invention, the end-capping agent is at least one of diphenyldihydroxysilane, hydroxymethyltrimethylsilane, and hydroxyethyltrimethylsilane.

In the present invention, the diisocyanate includes at least one of diphenylmethane diisocyanate, toluene diisocyanate, naphthalene diisocyanate and isophorone isocyanate.

In the present invention, the initiator is potassium persulfate.

In the present invention, the acrylic monomer includes at least one of styrene, methyl methacrylate, acrylic acid, and methacrylic acid.

Second, the present invention provides a kind of aforementioned preparation method, comprises the following steps:

S1 disperse the first part of silicon-containing unsaturated rosin-based polyurethane emulsion, acrylic monomer, and water to obtain a pre-emulsion;

Add water and the second part of silicon-containing unsaturated rosin-based polyurethane emulsion to the S2 primer reactor, then add the pre-emulsion dropwise to the primer reactor, and add the initiator dropwise at the same time.

S3 cools down, then adds a redox initiator, and neutralizes to obtain a core-shell emulsion.

In the present invention, each component of the raw material of the core-shell emulsion is calculated in parts by weight,

In S1, the first part contains 5-18 parts of silicon-containing unsaturated rosin-based polyurethane emulsion, 30-55 parts of acrylic monomer; specifically, 12-25 parts of styrene, 5-15 parts of methyl methacrylate, and 2-10 parts of acrylic acid 2-10 parts of methacrylic acid, 22-38 parts of water.

In S2, 15-25 parts of water, 0.2-5 parts of silicon-containing unsaturated rosin-based polyurethane emulsion in the second part, and 0.1-0.5 parts of initiator;

In S3, 0.03 to 0.1 part of redox initiator.

In the present invention, the redox system is composed of hydrogen peroxide and vitamin C. Specifically, 0.02-0.06 parts of hydrogen peroxide, and 0.01-0.03 parts of vitamin C.

Thirdly, the present invention provides the application of the core-shell emulsion in water-based paint.

<Example>

Example 1

The preparation method of core-shell emulsion comprises the steps:

①Put 20 parts of rosin, 4 parts of maleic anhydride, 10 parts of polyol (pentaerythritol), and 10 parts of methyl ethyl ketone solvent into the reaction kettle and raise the temperature to 185-200°C, and react for 3 hours. After the acid value is ≤50, cool down to 70°C. Unsaturated rosin resin is prepared;

②Add 10 parts of toluene diisocyanate into the reaction kettle, keep and control the temperature at 70-75°C for 2 hours, then detect that the NCO value is ≤10, add 2 parts of diphenyldihydroxysilane, and continue to keep warm at 70-75°C until no Up to NCO, add triethylamine to neutralize and adjust pH = 7, add 20 parts of water to disperse at a high speed, distill out methyl ethyl ketone solvent, so far the preparation of silicon-containing unsaturated rosin-based polyurethane emulsion is completed;

③ Disperse 10 parts of the above-mentioned silicon-containing unsaturated rosin-based polyurethane emulsion with 20 parts of styrene, 10 parts of methyl methacrylate, 5 parts of acrylic acid, 5 parts of methacrylic acid, and 30 parts of water to prepare a pre-emulsion; Add 20 parts of water and 2 parts of silicon-containing unsaturated rosin-based polyurethane emulsion to the kettle, drop the prepared pre-emulsion into the primer reaction kettle, and add 0.25 parts of initiator potassium persulfate (dilute and stir with 5 parts of water) Evenly), keep warm at 85-90°C. The dropwise reaction was performed for 3 hours, and the initiator was added dropwise for another 20 minutes. After the dropwise addition, the temperature was kept at 85 to 90° C. for 1.5 hours. Cool down to 65 to 70°C, add 0.05 parts of hydrogen peroxide and 0.03 parts of vitamin C, eliminate heat preservation for 30 minutes, then cool down to 45°C, add 5 parts of ammonia water to neutralize, and the rosin-modified polyurethane acrylic emulsion (product 1) is prepared.

Example 2

The preparation method of core-shell emulsion comprises the steps:

①Put 15 parts of rosin, 6 parts of maleic anhydride, 12 parts of polyol (trimethylolpropane), and 12 parts of methyl ethyl ketone solvent into the reaction kettle and raise the temperature to 185-200°C, react for 3 hours, and after the acid value is ≤50, cool down To 70 ℃, the preparation of unsaturated rosin resin is completed;

②Add 15 parts of toluene diisocyanate into the reaction kettle, keep and control the temperature at 70-75°C for 2 hours, then detect that the NCO value is ≤10, add 3 parts of diphenyldihydroxysilane, and continue to keep warm at 70-75°C until no Up to NCO, add triethylamine to neutralize and adjust pH = 7, add 25 parts of water to disperse at high speed, and then distill off butanone solvent under reduced pressure, so far the preparation of silicon-containing unsaturated rosin-based polyurethane emulsion is completed;

③ Disperse 15 parts of the above silicon-containing unsaturated rosin-based polyurethane emulsion with 18 parts of styrene, 8 parts of methyl methacrylate, 3 parts of acrylic acid, 7 parts of methacrylic acid, and 25 parts of water to prepare a pre-emulsion; Add 18 parts of water and 3 parts of silicon-containing unsaturated rosin-based polyurethane emulsion to the kettle, add the prepared pre-emulsion dropwise into the primer reaction kettle, and simultaneously add 0.2 parts of initiator potassium persulfate (dilute and stir with 5 parts of water) Evenly), keep warm at 85-90°C. The dropwise reaction was performed for 3 hours, and the initiator was added dropwise for another 20 minutes. After the dropwise addition, the temperature was kept at 85 to 90° C. for 1.5 hours. Cool down to 65 to 70°C, add 0.05 parts of hydrogen peroxide and 0.03 parts of vitamin C, eliminate heat preservation for 30 minutes, then cool down to 45°C, add 5 parts of ammonia water for neutralization, and the rosin-modified polyurethane acrylic emulsion (product 2) is prepared.

Example 3

The preparation method of core-shell emulsion comprises the steps:

①Put 12 parts of rosin, 2 parts of maleic anhydride, 8 parts of polyol (glycerin), and 8 parts of methyl ethyl ketone solvent into the reaction kettle and raise the temperature to 185-200°C, and react for 3 hours. After the acid value is ≤50, cool down to 70°C. Unsaturated rosin resin is prepared;

②Add 8 parts of toluene diisocyanate into the reaction kettle, keep and control the temperature at 70-75°C for 2 hours, then detect that the NCO value is ≤10, add 1.5 parts of hydroxymethyltrimethylsilane, and continue to keep warm at 70-75°C until Until there is no NCO, add triethylamine to neutralize and adjust pH = 7, add 18 parts of water to disperse at high speed, and then distill out butanone solvent, so far the silicon-containing unsaturated rosin-based polyurethane emulsion is prepared;

③ Disperse 8 parts of the above silicon-containing unsaturated rosin-based polyurethane emulsion with 15 parts of styrene, 8 parts of methyl methacrylate, 3 parts of acrylic acid, 5 parts of methacrylic acid, and 25 parts of water to prepare a pre-emulsion; Add 15 parts of water and 1 part of silicon-containing unsaturated rosin-based polyurethane emulsion to the kettle, drop the prepared pre-emulsion into the primer reaction kettle, and add 0.25 parts of initiator potassium persulfate (dilute and stir with 5 parts of water) Evenly), keep warm at 85-90°C. The dropwise reaction was performed for 3 hours, and the initiator was added dropwise for another 20 minutes. After the dropwise addition, the temperature was kept at 85 to 90° C. for 1.5 hours. Cool down to 65 to 70°C, add 0.03 parts of hydrogen peroxide and 0.02 parts of vitamin C, eliminate heat preservation for 30 minutes, then cool down to 45°C, add 5 parts of ammonia water for neutralization, and the rosin-modified polyurethane acrylic emulsion (product 3) is prepared.

<Comparative example>

Comparative example 1

A preparation method of polyurethane acrylic acid emulsion, comprising the steps of:

Add 10 parts of acetone, add 10 parts of TDI, add 8 parts of hydroxyethyl acrylate (NCO group and OH value MOL ratio 1:1.05) and raise the temperature to 60°C, react for 2 hours until there is no NCO value.

Then add dropwise mixed acrylic acid monomer (20 parts of styrene, 15 parts of butyl acrylate, 3 parts of acrylic acid, 15 parts of methyl methacrylate, 0.5 part of initiator benzoyl peroxide), dropwise for 2 to 3 hours, Keep warm for 1 hour, then add 0.5 parts of initiator benzoyl peroxide, keep warm for 2 hours, cool down to 90°C, add neutralizing agent triethylamine and stir for half an hour, add water to disperse for half an hour, evaporate acetone, cool down to 50°C Package.

<Test example>

The product 1-3 prepared in the embodiment and the product 4 prepared in the comparative example 1 were used as test samples.

1. Determination of the conventional properties of products 1-4, the results are shown in Table 1.

2. Measure the paint film properties of products 1-4, the results are shown in Table 2.

Table 1 General performance results of products 1-3

Table 2 The paint film performance results of products 1-3

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. The core-shell emulsion is characterized by comprising the following raw materials:

the unsaturated rosin-based polyurethane containing silicon as the shell layer,

as the acrylic monomer for the core layer,

the initiator is used for initiating the cross-linking bonding between the shell layer and the core layer and the self-crosslinking of the acrylic monomer of the core layer structure, and the acrylic double bond of the core layer is bonded with the double bond of the silicon-containing unsaturated rosin-based polyurethane emulsion.

2. The core-shell emulsion according to claim 1, wherein the preparation method of the silicon-containing unsaturated rosin-based polyurethane emulsion comprises the following steps:

in the presence of a reaction solvent, reacting rosin, maleic anhydride and polyol to obtain unsaturated rosin resin;

unsaturated rosin resin reacts with diisocyanate to obtain unsaturated rosin-based polyurethane resin;

adding an end-capping agent into the unsaturated rosin-based polyurethane resin to obtain unsaturated rosin-based polyurethane resin with a silicon-containing end group, and neutralizing, adding water and dispersing to obtain unsaturated rosin-based polyurethane emulsion with silicon.

3. The core-shell emulsion according to claim 2, wherein the raw materials of the silicon-containing unsaturated rosin-based polyurethane emulsion comprise, by weight, 12 to 25 parts of rosin, 2 to 8 parts of maleic anhydride, 5 to 18 parts of polyol, 5 to 18 parts of a reaction solvent, 0.5 to 5 parts of a blocking agent, 12 to 25 parts of water, and 7 to 18 parts of diisocyanate.

4. Core-shell emulsion according to claim 2 or 3, wherein the polyol comprises at least one of pentaerythritol, trimethylolpropane, glycerol.

5. The core-shell emulsion according to claim 2 or 3, wherein the end-capping agent is at least one of diphenyldihydroxysilane, hydroxymethyltrimethylsilane, and hydroxyethyltrimethylsilane.

6. Core-shell emulsion according to claim 1 or 2, wherein the acrylic monomer comprises at least one of styrene, methyl methacrylate, acrylic acid, methacrylic acid.

7. The method for preparing a core-shell emulsion according to any one of claims 1 to 6, comprising the steps of:

s1, dispersing a first part of silicon-containing unsaturated rosin-based polyurethane emulsion, an acrylic monomer and water to obtain a pre-emulsion;

s2, adding water and a second part of silicon-containing unsaturated rosin-based polyurethane emulsion into a bottoming reaction kettle, dropwise adding a pre-emulsion into the bottoming reaction kettle, dropwise adding an initiator at the same time, and carrying out heat preservation reaction after dropwise adding is finished;

and S3, cooling, adding a redox initiator, and neutralizing to obtain the core-shell emulsion.

8. The preparation method of the core-shell emulsion according to claim 7, wherein the raw materials of the core-shell emulsion comprise, in parts by weight,

in S1, 5-18 parts of a first part of silicon-containing unsaturated polyurethane rosin emulsion and 30-55 parts of an acrylic monomer;

in S2, 15 to 25 parts of water, 0.2 to 5 parts of second part silicon-containing unsaturated polyurethane rosin emulsion and 0.1 to 0.5 part of initiator;

in S3, 0.03-0.1 part of redox initiator.

9. Method for the preparation of core-shell emulsions according to claim 7 or 8, characterized in that the redox system consists of hydrogen peroxide and vitamin C.

10. Use of the core-shell emulsion according to any of claims 1 to 6 or the preparation process according to any of claims 7 to 9 in aqueous coatings.