CN102702484A - Epoxy modified water-based polyacrylamide curing agent and preparation method thereof - Google Patents

Abstract

The invention provides a curing agent which takes epoxy resin modified water-based polyacrylamide as an epoxy emulsion. The curing agent is a water-based curing agent with a compatible epoxy resin molecular structure, the compatibility and stability of the curing agent and the epoxy emulsion are improved, an organic solvent is not contained, and performance such as the chemical medicine resistance of coating films is improved obviously. A potassium peroxydisulfate catalyst is added into an acrylamide monomer to perform reaction to obtain the polyacrylamide emulsion. Polyamine is used, and a monoepoxy compound serving as an end-capping agent, namely butyl glycidyl ether 501, is dripped into the polyamine to perform end capping on amino. A product which is subjected to the end capping by 501 is added into the polyacrylamide emulsion to be stirred uniformly, and epoxy resin is added into the mixture to be modified to obtain the epoxy modified water-based polyacrylamide curing agent. According to the epoxy modified water-based polyacrylamide curing agent, epoxy resin modified water-based polyacrylamide is used as the curing agent of the epoxy emulsion. Compared with the coating film formed by the conventional water-based epoxy curing agent, the coating film formed by the prepared curing agent and the epoxy emulsion has the advantage that the acid and alkali resistance, corrosion resistance and the like are improved obviously.

Description

Epoxy-modified water-based polyacrylamide curing agent and preparation method thereof

technical field

The invention belongs to the technical field of chemical industry, and in particular relates to an epoxy-modified water-based polyacrylamide curing agent and a preparation method.

Background technique

On the basis of retaining the excellent adhesion, thermal stability, chemical resistance, insulation and other characteristics of the traditional epoxy system, the water-based epoxy coating system uses water as the dispersion medium and contains no or only a small amount of organic solvents , is a class of environmentally friendly polymer materials. With the increasingly urgent and strict requirements for environmental protection, water-based epoxy resins that do not contain volatile organic compounds (volatile organic compounds, VOC) or low-volatile organic solvents, and do not contain harmful air pollutants (non-hazardous air pollutants, NHAP) The system has become a hot spot of current research.

Waterborne epoxy curing agent is the key to the application of waterborne epoxy system. At present, it can only be said that it is aimed at a certain type of epoxy resin to synthesize a matching curing agent, so each development of a new curing agent can solve a problem in one aspect, which is equivalent to developing a new epoxy resin or epoxy resin. Opened up a new use of epoxy resin. It can be seen that the development of curing agent is of great significance.

The waterborne epoxy coating system is composed of epoxy resin and waterborne epoxy curing agent. Waterborne epoxy curing agent is an important component that affects the physical and chemical properties of waterborne epoxy resin systems, and has become a focus of attention and research in related fields at home and abroad. At present, the waterborne epoxy system can be divided into type I system and type II system according to the film forming method and the physical state of the two components.

Type I water-based epoxy system is composed of low-molecular liquid epoxy resin and water-soluble amine curing agent. In this system, the curing agent is both a crosslinking agent and an emulsifier. This type of curing agent is based on polyamines. The introduction of a surface-active segment makes it an amphiphilic molecule, which has a strong emulsifying effect. Due to the use of liquid resin, there is no need to add solvents to the type I water-based epoxy system, and the VOC of the system can be zero. It can be formulated into zero-VOC and NHAP coatings, and the hardness of the coating film increases rapidly, but the resin used is liquid, and the surface dry time is long after the water evaporates; the viscosity of the system increases rapidly with the prolongation of the storage time, showing that it is applicable Short term; poor corrosion resistance.

Type II water-based epoxy system is composed of self-emulsifying high-molecular-weight solid epoxy resin and curing agent. Self-emulsifying high-molecular-weight epoxy resin is solid at room temperature and has a softening point of 60-80°C. Formulated as an emulsion, which usually contains small amounts of HAPs. The curing agent has good compatibility with type II epoxy emulsion. Most of them contain NHAP as a film-forming aid, and the surface drying speed of the system is fast. The curing agent of this system needs to migrate from the water phase to the epoxy resin, thereby reducing the concentration of reactants and extending the pot life. However, the type II waterborne epoxy system has the disadvantages of containing organic volatile solvents and uneven coating surface.

The polyacrylamide synthesized by the aqueous solution polymerization method has simple operation, high yield and good water solubility. Based on the water-based epoxy curing agent, this study proposes a new epoxy curing agent and its preparation method using epoxy-modified water-based polyacrylamide. The curing agent prepared by epoxy-modified polyacrylamide is a water-based curing agent containing a molecular structure of epoxy resin, which improves the compatibility with epoxy resin and overcomes the poor corrosion resistance and chemical resistance of type I water-based epoxy system. It also overcomes the disadvantages of type II water-based epoxy system including organic solvents and uneven coating surface.

Contents of the invention

The present invention proposes to use epoxy resin modified water-based polyacrylamide as the curing agent of epoxy emulsion. The curing agent is a water-based curing agent containing epoxy resin molecular structure, which improves the compatibility and stability with epoxy emulsion , does not contain organic solvents. Polyacrylamide has amide bonds and has good acid and alkali resistance and corrosion resistance. Therefore, the chemical resistance of the coating film can be significantly improved. Added with polyamines, a water-based epoxy curing agent with self-emulsifying properties was prepared. The coating film obtained by using the curing agent has excellent performance, simple process, easy operation and low cost.

The preparation method of epoxy resin modified water-based polyacrylamide curing agent of the present invention, the steps are as follows:

(1) Dissolve acrylamide monomer in water to prepare a solution with a concentration of about 30%; under _N2 conditions, 50-70°C, add 1‰ initiator potassium persulfate (potassium persulfate) equivalent to the total mass of monomer and water , react for 2-4h to obtain polyacrylamide emulsion;

(2) Select a polyamine and add an equimolar monoepoxide butyl glycidyl ether dropwise to prepare a capped product; the reaction temperature is 50-70°C, and the reaction time is 1.5-2.5 hours;

(3) Take the product in (2), add it dropwise to the product in (1), stir evenly, add epoxy resin dropwise (5-15% of the molar weight relative to the amino molar weight), and heat up to 45-65 °C, continue to react for 2 to 3 hours to obtain the compound;

The polyacrylamide prepared by the aqueous solution method in the step (1) has a molecular weight of about 2-5×10 ⁶ .

One polyamine in the step (2) is diethylenetriamine or triethylenetetramine.

In the step (3), the epoxy resin is E-44, 128, E-42

Preparation of two-component waterborne epoxy resin coating film

Component A: water-based epoxy resin curing agent Component B: water-based epoxy resin emulsion

Mix according to the ratio of component A (active hydrogen value mol/g): component B (epoxy group value mol/g) = 1:1, mix evenly, apply on the iron sheet with a brush, and heat at 40-80°C Forms a transparent coating film.

The polyacrylamide prepared in step (1) has a molecular weight of about 2 to 5×10 ⁶

A polyamine in step (2) is diethylenetriamine or triethylenetetramine

Epoxy resin is E-44,128,E-42 in the step (3)

The invention proposes to prepare a new epoxy curing agent by modifying waterborne polyacrylamide with epoxy resin. The curing agent is a water-based curing agent containing epoxy resin molecular structure, which improves the compatibility and stability with the epoxy emulsion, does not contain organic solvents, and the chemical resistance and corrosion resistance of the coating film are significantly improved.

The physical property parameter of gained waterborne epoxy resin curing agent:

The performance parameters of film formation after mixing with epoxy emulsion are as follows:

The prepared epoxy-modified polyacrylamide curing agent is a water-based curing agent containing epoxy-friendly molecular structure, which improves the compatibility and stability with epoxy emulsion, and significantly improves the acid and alkali resistance and corrosion resistance of the paint film. and other performance.

Detailed ways

Below by example the present invention is described in further detail:

Example 1

(1) Synthesis of polyacrylamide emulsion: First, 30.5g of acrylamide monomer was dissolved in 69.5g of water to prepare a solution with a concentration of 30.5%. The reactor is composed of a thermometer, a constant speed stirrer and a 250mL four-necked bottle with a condenser. Under the condition of N ₂ , stirring at a constant temperature of 50° C., adding 0.1 g of initiator potassium persulfate (KPS), and reacting for 2 hours. Obtain polyacrylamide emulsion;

(2) Synthesis of capped product: Add 5.15g of diethylenetriamine to 6.5g of butyl glycidyl ether 501 dropwise to prepare a capped product; the reaction temperature is 50°C, and the reaction time is 1.5h;

(3) Take the product in (2), add it dropwise to the product in (1), stir evenly, add dropwise 4.3g (5% of the molar weight relative to the amino molar weight) of epoxy resin E-44, and heat up to 45°C, continue to react for 2h to obtain the compound;

(4) Preparation of two-component waterborne epoxy resin paint film

Component A: water-based epoxy resin curing agent Component B: water-based epoxy resin emulsion

Mix according to the ratio of component A (active hydrogen value mol/g): component B (epoxy group value mol/g) = 1:1, mix evenly, apply it on the iron sheet with a brush, and heat it at 40°C to form a transparent coating film.

The paint film performance of gained waterborne epoxy resin curing agent:

Example 2

(1) Synthesis of polyacrylamide emulsion: First, 30.5g of acrylamide monomer was dissolved in 69.5g of water to prepare a solution with a concentration of 30.5%. The reactor is composed of a thermometer, a constant speed stirrer and a 250mL four-necked bottle with a condenser. Under the condition of N ₂ , stirring at a constant temperature of 70° C., adding 0.1 g of initiator potassium persulfate (KPS), and reacting for 4 hours. Obtain polyacrylamide emulsion;

(2) Synthesis of capped product: Add 5.15g of diethylenetriamine to 6.5g of butyl glycidyl ether 501 dropwise to prepare a capped product; the reaction temperature is 70°C, and the reaction time is 2.5h;

(3) Take the product in (2), add it dropwise to the product in (1), stir evenly, add dropwise 8.2g (10% of the molar weight relative to the amino molar weight) of epoxy resin E-42, and heat up to 65°C, continue to react for 3h to obtain the compound;

(4) Preparation of two-component waterborne epoxy resin paint film

Component A: water-based epoxy resin curing agent Component B: water-based epoxy resin emulsion

Mix according to the ratio of component A (active hydrogen value mol/g): component B (epoxy group value mol/g) = 1:1, mix evenly, apply it on the iron sheet with a brush, and heat it at 60°C to form a transparent coating film.

The paint film performance of gained waterborne epoxy resin curing agent:

Example 3

(1) Synthesis of polyacrylamide emulsion: First, 30.5g of acrylamide monomer was dissolved in 69.5g of water to prepare a solution with a concentration of 25%. The reactor is composed of a thermometer, a constant speed stirrer and a 250mL four-necked bottle with a condenser. Under the condition of N ₂ , stirring at a constant temperature of 70° C., adding 0.1 g of initiator potassium persulfate (KPS), and reacting for 3 hours. Obtain polyacrylamide emulsion;

(2) Synthesis of capped product: Add 7.3g of triethylenetetramine to 6.5g of butyl glycidyl ether 501 dropwise to prepare a capped product; the reaction temperature is 60°C, and the reaction time is 2h;

(3) Take the product in (2) and add it dropwise to the product in (1). After stirring, add 12.9g (15% of the molar weight relative to the amino molar weight) of epoxy resin E-44 dropwise, and heat up To 55°C, continue to react for 2.5h to obtain the compound;

(4) Preparation of two-component waterborne epoxy resin paint film

Component A: water-based epoxy resin curing agent Component B: water-based epoxy resin emulsion

Mix according to the ratio of component A (active hydrogen value mol/g): component B (epoxy group value mol/g) = 1:1, mix evenly, apply it on the iron sheet with a brush, and heat it at 80°C to form transparent coating film.

The paint film performance of gained waterborne epoxy resin curing agent:

Example 4

(1) Synthesis of polyacrylamide emulsion: First, 30.5g of acrylamide monomer was dissolved in 69.5g of water to prepare a solution with a concentration of 25%. The reactor is composed of a thermometer, a constant speed stirrer and a 250mL four-necked bottle with a condenser. Under the condition of N ₂ , stirring at a constant temperature of 60° C., adding 0.1 g of initiator potassium persulfate (KPS), and reacting for 2.5 hours. Obtain polyacrylamide emulsion;

(2) Synthesis of capped product: 7.3g of triethylenetetramine was added dropwise with 6.5g of butyl glycidyl ether 501 to prepare a capped product; the reaction temperature was 55°C, and the reaction time was 2h;

(3) Take the product in (2), add it dropwise to the product in (1), stir evenly, add dropwise 10g (10% of the molar weight relative to the amino molar weight) of epoxy resin 128, and raise the temperature to 60°C, Continue to react for 2h to obtain the compound;

(4) Preparation of two-component waterborne epoxy resin paint film

Component A: water-based epoxy resin curing agent Component B: water-based epoxy resin emulsion

Mix according to the ratio of component A (active hydrogen value mol/g): component B (epoxy group value mol/g) = 1:1, mix evenly, apply it on the iron sheet with a brush, and heat it at 60°C to form a transparent coating film.

The paint film performance of gained waterborne epoxy resin curing agent:

The present invention is not limited to the technology described in the embodiment, its description is illustrative, not restrictive, the authority of the present invention is defined by the claims, based on those skilled in the art can change and reorganize according to the present invention The technologies related to the present invention obtained by such methods are all within the protection scope of the present invention.

Claims (5)

1. with the solidifying agent of epoxy resin modified aqueous SEPIGEL 305 as epoxy emulsion; It is characterized in that solidifying agent is the waterborne curing agent that contains close epoxy resin molecular structure.

2. the preparation method of the epoxy resin modified aqueous polyacrylamide amine hardener of claim 1 is characterized in that step is following:

(1) earlier the acrylamide monomer concentration that is mixed with soluble in water is about 30% solution; N ₂Under the condition, 50～70 ℃, add 1 ‰ initiator potassium persulfate be equivalent to monomer and water total mass (, react 2 ~ 4h, obtain polyacrylamide emulsion;

(2) choose a polyamine species, drip equimolar mono-epoxy compounds butylglycidyl ether, prepare the end-blocking product; Temperature of reaction is 50～70 ℃, and the reaction times is 1.5～2.5h;

(3) get the product in (2), be added drop-wise in the product of (1), the back that stirs drips the epoxy resin of (molar weight is with respect to 5～15% of amino molar weight), is warmed up to 45～65 ℃, continues reaction 2～3h and obtains synthetics.

3. method as claimed in claim 2 is characterized in that the SEPIGEL 305 that aqua-solution method prepares in the said step (1), and its molecular weight is about 2～5 * 10 ⁶

4. method as claimed in claim 2 is characterized in that a polyamine species is diethylenetriamine or triethylene tetramine in the said step (2).

5. method as claimed in claim 2 is characterized in that in the said step (3) that epoxy resin is E-44,128 or E-42.