KR102044524B1 - Aqueous epoxy resin dispersion and paint composition comprising the same - Google Patents

Abstract

The present invention relates to an aqueous epoxy resin dispersion and a coating composition including the same, wherein the coating composition can form a coating film having excellent impact resistance as the aqueous epoxy resin dispersion is included.

Description

Aqueous Epoxy Resin Dispersion and Coating Composition Comprising The Same {AQUEOUS EPOXY RESIN DISPERSION AND PAINT COMPOSITION COMPRISING THE SAME}

The present invention relates to an aqueous epoxy resin dispersion that can be used as a subject of a medium anticorrosive coating or a plant coating.

Epoxy resins exhibit a strong hardening structure by easily reacting with amines or acids, and in particular, bisphenol A epoxy resins are used in many industrial fields due to their chemical resistance, heat resistance, high hardness, and flexibility. An example of the industrial field is a paint field, and epoxy resin is used as a main component of the paint field in the paint field.

On the other hand, due to continuous environmental regulations, oil-based resins used in the paint field are rapidly being converted into water-based resins. Accordingly, methods for making epoxy resins also have an aqueous property of being dispersed in a solvent such as water It is studied a lot. Examples of the method include a method of dispersing an epoxy resin with an emulsifier or introducing a hydrophilic substituent into the epoxy resin and dispersing it in water.

However, the aqueous epoxy resin dispersions obtained through the above methods show limitations in obtaining a coating film having physical properties required in the market. In particular, the aqueous bisphenol A-type epoxy resin dispersion is a situation that the impact resistance of the coating film is significantly lowered, so that it is difficult to use in the medium coating paint, or the plant coating paint.

Republic of Korea Patent Publication No. 1998-042879

The present invention provides an aqueous epoxy resin dispersion capable of improving the impact resistance of the coating film.

The present invention also provides a coating composition comprising the aqueous epoxy resin dispersion.

The present invention provides an aqueous epoxy resin dispersion containing a modified epoxy resin obtained by reacting a reactant of a polyether polyol with anhydrous acid with a bisphenol A epoxy resin.

Moreover, this invention provides the coating composition containing the said aqueous epoxy resin dispersion and an amine-type hardening | curing agent.

Since the aqueous epoxy resin dispersion of the present invention includes a modified epoxy resin into which a flexible polyether polyol (specifically, polypropylene glycol) is introduced, it may be mixed with a curing agent to be used as a coating composition (especially a coating material for container coating). In this case, it is possible to form a coating film having excellent impact resistance as well as adhesion, water resistance, and rust resistance.

Hereinafter, the present invention will be described in detail.

1. Aqueous Epoxy Resin Dispersion

The aqueous epoxy resin dispersion of the present invention includes a modified epoxy resin.

The modified epoxy resin contained in the aqueous epoxy resin dispersion of the present invention is obtained by reacting a reactant of a polyether polyol with anhydrous acid with a bisphenol A epoxy resin.

The polyether polyol used to obtain the reactant may be at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol, and specifically, may be polypropylene glycol. In addition, the polyether polyol may be used having a weight average molecular weight in the range of 400 to 10,000, using a polyether polyol having a weight average molecular weight within the above range alone or mixing a polyether polyol having two or more weight average molecular weights Can be used.

The anhydrides used to obtain the reactants include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, It may be at least one member selected from the group consisting of maleic anhydride, succinic anhydride, and trimellitic anhydride.

The reactant is an intermediate obtained by ring-opening anhydrous acid with a polyether polyol while the polyether polyol and anhydrous acid are reacted. In this case, the reaction ratio of the polyether polyol and anhydrous acid may be a molar ratio of 1: 1.5 to 3. When the reaction ratio is less than 1: 1.5 molar ratio, the viscosity may be increased to decrease the water dispersibility of the resin, and when the molar ratio of 1: 3 is exceeded, unreacted anhydrous acid may be present to express the properties of the polyether polyol. It can be difficult.

In addition, a mixture of the polyether polyol and anhydrous acid may be reacted at 130 to 140 ° C. for 2 to 4 hours to obtain a reactant.

The bisphenol A epoxy resin reacting with the reactant to obtain the modified epoxy resin may be a bisphenol A epoxy resin having an epoxy equivalent (EEQ) of 190 to 500 g / mol.

The epoxy equivalent of the said bisphenol-A epoxy resin can be adjusted individually or in mixture of 2 or more types of commercially available bisphenol-A epoxy resin. In addition, bisphenol A type epoxy resins having a specific epoxy equivalent (eg, epoxy equivalent between 190 g / mol and 500 g / mol) can be prepared and used directly.

Specifically, a bisphenol A type epoxy resin having an epoxy equivalent of 190 g / mol (for example, Kukdo Chemical YD-128 or a third-party equivalent grade resin) is placed in a flask, and a bisphenol A type epoxy resin having a different epoxy equivalent is used as the epoxy equivalent. 0 to 23 parts by weight of the bisphenol A epoxy resin of 190 g / mol is mixed. At this time, when mixing up to 23 parts by weight, the epoxy equivalent may reach 475 g / mol, and the epoxy equivalent is increased in proportion to the mixing amount. Next, a reaction catalyst (eg, ethyl triphenyl phosphonium bromide, tetra phenyl phosphonium bromide, tetra phenyl phosphonium chloride, etc.) is added to the mixed epoxy resin to 0.05 of the mixed amount (amount of the mixed epoxy resin). To 0.5 parts by weight to add to 130 to 140 ℃. By the reaction for the next 2 to 4 hours it can be prepared a bisphenol A epoxy resin having a specific epoxy equivalent.

The reaction between the reactant and the bisphenol A epoxy resin may be performed until the epoxy equivalent of the resulting modified epoxy resin is close to the theoretical epoxy equivalent. In this case, the theoretical epoxy equivalent may be a value obtained by Equation 1 below.

[Equation 1]

This theoretical epoxy equivalent, ie, the epoxy equivalent of the resulting modified epoxy resin, may be between 200 and 750 g / mol. When the epoxy equivalent of the modified epoxy resin is out of the range, it may be difficult to achieve dispersion of the dispersion due to low viscosity or high viscosity, or even to achieve the desired impact resistance even if the dispersion is performed.

Meanwhile, the aqueous epoxy resin dispersion of the present invention may further include at least one selected from the group consisting of an emulsifier, a dispersant, an antifoaming agent, and a solvent.

The emulsifier further included in the aqueous epoxy resin dispersion of the present invention increases the water dispersion stability of the dispersion. As the emulsifier, a nonionic emulsifier may be used, and specifically, an emulsifier of a block polymer type of ethylene oxide (EO) -propylene oxide (PO) -ethylene oxide (EO) bond may be used. Here, in consideration of the water dispersion stability of the dispersion more, the weight average molecular weight of propylene oxide (PO) is 1,000 to 4,000 (specifically 2,000 to 3,000), the weight average molecular weight of one ethylene oxide (EO) 2,000 to 10,000 (4,000) To 8,000), a block polymer type emulsifier can be used.

The amount of the emulsifier may be 7 to 15 parts by weight based on the total weight of the modified epoxy resin. When the amount of the emulsifier is less than 7 parts by weight, the dispersion may not be well dispersed. When the amount of the emulsifier is more than 15 parts by weight, the water resistance may be lowered, thereby limiting the application of the dispersion.

The dispersant further included in the aqueous epoxy resin dispersion of the present invention increases the water dispersibility of the dispersion. As the dispersant, commonly used components (for example, propylene oxide (PO) -ethylene oxide (EO) -propylene oxide (PO) block polymer type, or silicone type) may be used.

The amount of the dispersant may be 0.01 to 1 part by weight based on the total weight of the modified epoxy resin. When the amount of the dispersant is less than 0.01 parts by weight, the dispersion may not be well dispersed, and when it exceeds 1 part by weight, dispersion stability may be lowered.

The antifoaming agent further included in the aqueous epoxy resin dispersion of the present invention controls foaming and leveling. As the antifoaming agent, conventionally used components (for example, propylene oxide (PO) -ethylene oxide (EO) -propylene oxide (PO) block polymer type or silicone type) may be used.

The amount of the antifoaming agent may be 0.01 to 1 part by weight based on the total weight of the modified epoxy resin. When the amount of the antifoaming agent is less than 0.01 parts by weight, the dispersion may not be well dispersed. When the amount of the antifoaming agent is more than 1 part by weight, the cracker or the leveling of the dispersion may be induced.

The solvent further contained in the aqueous epoxy resin dispersion of the present invention adjusts the viscosity of the dispersion. As the solvent, components commonly used may be used, and specifically, deionized water, butyl cellosolve, 1-methoxy-2-propanol, dipropylene glycol-n-butyl ether, isopropyl alcohol, ethylene glycol, Texanol, butyl carbitol, or mixtures thereof may be used.

The amount of the solvent may be 1 to 20 parts by weight based on the total weight of the modified epoxy resin. When the amount of the solvent used is less than 1 part by weight or more than 20 parts by weight, it may be difficult to implement a dispersion having a required viscosity.

Such an aqueous epoxy resin dispersion of the present invention may be prepared by preparing a modified epoxy resin, followed by mixing and dispersing the prepared modified epoxy resin with an emulsifier, a dispersant, an antifoaming agent, and a solvent.

Specifically, the modified epoxy resin is added to the reactor, an emulsifier and a solvent are added, and then the temperature is increased to a dispersion temperature. In this case, the dispersion titration temperature may be a temperature when the modified epoxy resin, the emulsifier, and the solvent are mixed at a viscosity of 10,000 to 30,000 cPs, and the maximum dispersion titration temperature may be 95 ° C. The 95 ℃ is considering the boiling point of the deionized water as a dispersion medium, if it exceeds 95 ℃ can be mixed with other solvents to lower the viscosity and dispersion titration temperature.

Then, after raising the temperature to the appropriate dispersion temperature, the antifoaming agent and the dispersant are mixed and uniformly mixed for about 30 minutes. When the mixing is completed, high speed stirring is performed, and the deionized water is slowly added dropwise to measure the viscosity continuously. When the viscosity is reached, when the maximum viscosity is reached, it is maintained for 1 hour, followed by further dropwise addition of deionized water, followed by cooling to prepare an aqueous epoxy resin dispersion.

The aqueous epoxy resin dispersion prepared as described above may have a solid content of 50 to 75% by weight, a total epoxy equivalent of 250 to 1,500 g / mol, and a viscosity at 25 ° C. of 10 to 1,000 cPs.

The aqueous epoxy resin dispersion according to the present invention includes a modified epoxy resin in which polyether polyol having excellent flexibility is introduced, and when used as a main resin of the coating composition, the impact resistance of the coating film formed of the coating composition can be significantly increased. have.

2. Paint Composition

The coating composition of the present invention contains an aqueous epoxy resin dispersion and an amine curing agent.

The aqueous epoxy resin dispersion contained in the coating composition of the present invention is described in the '1. It is the same as that described in 'Aqueous Epoxy Resin Dispersion', and thus the description thereof is omitted.

The amine curing agent included in the coating composition of the present invention induces a curing reaction of the modified epoxy resin, and a conventionally known component may be used.

Such a coating composition of the present invention can form a coating film excellent in rust resistance, adhesion and impact resistance as it contains an aqueous epoxy resin dispersion. Therefore, the coating composition of the present invention can be usefully used as a paint coating for medium coating, or a paint coating for plants.

Hereinafter, the present invention will be described in detail with reference to the following Examples. However, the following examples are merely to illustrate the invention, the present invention is not limited by the following examples.

Example 1 Preparation of Aqueous Epoxy Resin Dispersion

1) reactant preparation

Into a four-necked round flask, 800 g of polypropylene glycol having a weight average molecular weight of 800 and 304 g of tetrahydrophthalic anhydride were added, and a nitrogen gas pipe, an H-type separator, a stirrer, a thermometer, and a heater were installed. The temperature was raised at and maintained at 140 ° C. for 3 hours. After cooling, a reaction product crystallized to white (anhydrous intermediate resin) was obtained.

2) modified epoxy resin

13 g of bisphenol A type epoxy resin 1 (Kukdo Chemical, YD-128), 67 g of bisphenol A type epoxy resin 2 (Kukdo Chemical, YD-011) in a four-necked round flask, the reaction product (opened with polypropylene glycol) 20 g of intermediate resin) was added, and a nitrogen gas pipe, an H-type separator, a stirrer, a thermometer, and a heater were installed, and the temperature was raised to 130 ° C. at a rate of 20 ° C. per hour. Thereafter, the epoxy equivalent was measured once per hour, and when the epoxy equivalent reached 630 g / mol, the reaction was terminated and cooled to obtain a modified epoxy resin.

3) Aqueous Epoxy Resin Dispersion Preparation

10 g of an emulsifier (F108, Adeka Co., Ltd.) and 5 g of butyl cellosolve were added to the obtained modified epoxy resin, and the temperature was raised to 85 ° C. and stirred for 30 minutes. After completion of the stirring, dispersant (Adeka Co., L-64) and antifoaming agent (BYK-024) were added 0.08 g each and stirred for another 30 minutes, and then the stirrer was changed to a high speed stirrer (1000 rpm or more) and then 900 rpm. Deionized water was added dropwise at 1 g / min. After 22 g of deionized water was added dropwise to adjust the viscosity to 25,000 cPs, the dropwise addition was stopped for 1 hour at that viscosity and the stirring was maintained. Next, 63 g of deionized water was added dropwise at a rate of 1 g / min, followed by cooling to room temperature to prepare an aqueous epoxy resin dispersion. The prepared aqueous epoxy resin dispersion had a solid content (NV) of 55% by weight, a viscosity of 150 cPs, and an epoxy equivalent of 1,250 g / mol.

Comparative Example 1

1) Epoxy Resin Preparation

Bisphenol A epoxy resin 2 (Kukdo Chemical, YD-011) was prepared.

2) Aqueous Epoxy Resin Dispersion Preparation

100 g of the bisphenol A epoxy resin 2 (Kukdo Chemical, YD-011) was placed in a four-necked round flask, and a nitrogen gas pipe, an H-type separator, a stirrer, a thermometer, and a heater were installed, followed by an emulsifier (Adeca, F108). 10 g) and 5 g of butyl cellosolve were added, and the mixture was heated to 85 ° C. and stirred for 30 minutes. After completion of stirring, dispersant (Adeka Co., L-64) and antifoaming agent (BYK-024) were added 0.08g each and stirred for another 30 minutes, and then the stirrer was changed to a high speed stirrer (1000rpm or more) and 900 rpm. Deionized water was added dropwise at 1 g / min. Thereafter, 20 g of deionized water was added dropwise to adjust the viscosity to 25,000 cPs, and then the dropwise addition was stopped for 1 hour at the viscosity and the stirring was maintained. Next, 65 g of deionized water was added dropwise at a rate of 1 g / min, followed by cooling to room temperature to prepare an aqueous epoxy resin dispersion. The prepared aqueous epoxy resin dispersion had a solid content (NV) of 55% by weight, a viscosity of 120 cPs, and an epoxy equivalent of 950 g / mol.

Comparative Example 2

Epoxy resin dispersion contains EP387 (polyethylene glycol modified type epoxy resin by epoxy-hydroxy reaction) of Allnex Co., Ltd. with 55% solids (NV) by weight, epoxy equivalent of 1,000 g / mol and viscosity of 2,700 cPs ) Was used.

Comparative Example 3

Epoxy resin dispersion contains AR555 (Polyethylene glycol-modified epoxy resin by epoxy-hydroxy reaction) of Air products of 55% solids (NV) by weight, epoxy equivalent of 550 g / mol and viscosity of 80 cPs ) Was used.

Production Example 1 and Comparative Production Examples 1 to 3

An amine curing agent (Anquamine 401, Air products, Inc.) was mixed with the epoxy resin dispersions of Example 1 and Comparative Examples 1 to 3 in an equivalent ratio of 1: 0.8 to prepare paint compositions, respectively.

The prepared coating composition was airless spray-coated to a 1.6T-thick iron plate at a thickness of 50 μm, and then baked at 80 ° C. for 12 hours. The properties of the coating film were evaluated in the following manner for the calcined hardened iron plate, and the results are shown in Table 1 below.

1. Antirust

Rust: Observe the condition of the coating after 1,000 hours of salt spray

Creep: Salt spray 1,000 hours after cross-cut, length measured from cutting site

Blister: Observe the condition of the coating after 1,000 hours of salt spray

2. Adhesion: Determination of adhesion state after 1,000 hours of salt spray

3. Impact resistance: Check the cracks after impacting the coating film under each condition

division Preparation Example 1 Comparative Production Example 1 Comparative Production Example 2 Comparative Production Example 3 Antirust

Rust 10 9 9 9 Creep 2.58 2.5 2.5 2.3 Blister 10 10 10 10 Adhesion 3B 3B 3B 3B Impact resistance

Front 60Lbs pass Fail Fail pass 5Lbsinch pass pass pass pass 8 Lbsinch pass Fail Fail Fail

Referring to Table 1 above, it can be seen that as the coating composition is formed of the coating composition using the aqueous epoxy resin dispersion of the present invention, a coating film having excellent impact resistance and anti-rusting property and adhesion property is formed.

Claims (9)

A modified epoxy resin obtained by reacting a reactant of a polyether polyol with anhydrous acid with a bisphenol A epoxy resin,
An aqueous epoxy resin dispersion, wherein the reaction ratio of the polyether polyol and the anhydrous acid is in a molar ratio of 1: 1.5 to 3. The method according to claim 1,
Wherein the polyether polyol is at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol. The method according to claim 1,
The acid anhydride is phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, maleic anhydride, swelling An aqueous epoxy resin dispersion, which is at least one selected from the group consisting of nick anhydride and trimellitic anhydride. delete The method according to claim 1,
The bisphenol A epoxy resin is an epoxy epoxy resin dispersion of the epoxy equivalent (EEQ) is 190 to 500 g / mol. The method according to claim 1,
Wherein the modified epoxy resin has an epoxy equivalent weight (EEQ) of 200 to 750 g / mol. The method according to claim 1,
An aqueous epoxy resin dispersion further comprising one or more selected from the group consisting of emulsifiers, dispersants, antifoaming agents, and solvents. The method according to claim 7,
An aqueous epoxy resin dispersion having a solids content of 50 to 75% by weight, a total epoxy equivalent weight (EEQ) of 250 to 1,500 g / mol and a viscosity at 25 ° C. of 10 to 1,000 cPs. An aqueous epoxy resin dispersion according to any one of claims 1 to 3 and 5 to 8, and
Coating composition containing an amine hardener.