KR102326226B1 - Polyamide curing agent having free volume provided by monoacid and method for preparing the same - Google Patents

Abstract

The present invention relates to a polyamide curing agent and a method for manufacturing the same, and more particularly, monoacid that provides free volume to the polymer chain is introduced, and when applied to a heavy-duty epoxy paint, adhesion, rust prevention, low temperature drying, repainting , and to a polyamide curing agent capable of providing a coating film that excellently satisfies all of topcoat adhesion, water whitening resistance, and paint spreadability, and a method for manufacturing the same.

Description

POLYAMIDE CURING AGENT HAVING FREE VOLUME PROVIDED BY MONOACID AND METHOD FOR PREPARING THE SAME

The present invention relates to a polyamide curing agent and a method for manufacturing the same, and more particularly, monoacid that provides free volume to the polymer chain is introduced, and when applied to a heavy-duty epoxy paint, adhesion, rust prevention, low temperature drying, repainting , and to a polyamide curing agent capable of providing a coating film that excellently satisfies all of topcoat adhesion, water whitening resistance, and paint spreadability, and a method for manufacturing the same.

For heavy-duty anticorrosive paint, a two-component paint is used by mixing the main agent and the hardener when painting, and the main material is mainly epoxy resin. As a curing agent for curing the epoxy resin, an amine-based curing agent has been traditionally used. Types of amine-based curing agents include aliphatic amines, cycloaliphatic amines, aromatic amines, etc. as pure amines, and amine adducts, cyanoethylated amines, Mannich-type amines (phenalkamines), and polyamides as modified amines. , amidoamines, and the like.

Recently, Mannich (phenalkamine) type and polyamide type hardeners have been mainly used as hardeners for heavy-duty paints, and research on them has been continued. For example, in Korea Patent No. 10-0744821, an epoxy adduct amine curing agent prepared by reacting a Mannich curing agent with an epoxy compound and an amine compound in which primary and tertiary amines coexist in a molecule are reacted alone or by Mannich reaction A prepared polyamine curing agent is disclosed. In addition, Korean Patent Laid-Open Patent Nos. 10-2014-0045816, 10-2012-0110263, and 10-2013-0096825 use a monomer containing thiol or sulfur when preparing a polyamide-type curing agent in order to increase rust prevention and adhesion properties. A method is disclosed.

However, the conventional curing agents described above need improvement in one or more of the physical properties such as coating film curing speed, substrate adhesion, low temperature drying, repainting, urethane topcoat adhesion, and rust prevention. There is a demand for the development of a curing agent for an epoxy paint that can be excellently satisfied. Furthermore, as the polyamide type is used for coating on non-ferrous metal substrates as well as metal substrates in recent years, better adhesion performance is required, and additional research on polyamide type hardener is required.

An object of the present invention is a polyamide curing agent that can provide a coating film that excellently satisfies all of adhesion, rust prevention, low temperature drying, repainting, top coat adhesion, water whitening resistance, and spreadability when applied to heavy-duty epoxy paints, and To provide a manufacturing method thereof.

The polyamide curing agent of the present invention includes a polyamide resin resulting from a condensation reaction between an acid mixture including a fatty acid, a fatty acid dimer, and a monoacid providing free volume, and an amine having at least one primary amine group in the amine molecule.

The method for preparing a polyamide curing agent of the present invention comprises condensation reaction of an acid mixture comprising a fatty acid, a fatty acid dimer, and a monoacid providing free volume with an amine having at least one primary amine group in the molecule.

The coating film formed by applying the polyamide curing agent of the present invention to the heavy-duty epoxy paint is excellent in adhesion, rust prevention, low-temperature drying, repainting, topcoat adhesion, water whitening resistance and spreadability.

Hereinafter, the present invention will be described in detail.

As used herein, the term “free volume” refers to a space that can be formed around the end or middle of a polymer chain so that the polymer chain can move freely with respect to other polymer chains surrounding it.

The acid mixture used to prepare the polyamide curing agent of the present invention comprises a fatty acid, a fatty acid dimer and a monoacid that provides free volume.

As the fatty acid, specifically, saturated or unsaturated C ₁₄ -C ₂₈ aliphatic carboxylic acid may be used alone or in combination, for example, soybean oil fatty acid, tall oil fatty acid, castor oil fatty acid, rice bran oil fatty acid, linseed oil fatty acid, coconut oil One selected from the group consisting of fatty acids, lauric acid, linoleic acid, and combinations thereof may be used. According to one embodiment of the present invention, tall oil fatty acid may be used.

As the fatty acid dimer, a soybean oil fatty acid dimer, a tall oil fatty acid dimer, or a combination thereof may be used. According to one embodiment of the present invention, soybean oil fatty acid dimer may be used.

The monoacid providing the free volume is a monoacid having a structure that allows the chain ends or the middle of the resin to have a free volume when introduced into the polyamide resin. Specifically, C ₆ -C ₁₄ aromatic monocarboxylic acid , C ₃ -C ₁₂ aliphatic monocarboxylic acid, C ₆ -C ₁₄ aromatic-C ₃ -C ₁₂ aliphatic monocarboxylic acid and combinations thereof may be used, for example, benzoic acid, butyric acid, 4- One selected from the group consisting of phenyl-benzoic acid, 3-phenylpropanoic acid, neononanoic acid, neodecanoic acid, and combinations thereof may be used. According to one embodiment of the present invention, one selected from the group consisting of benzoic acid, butyric acid, neodecanoic acid, and combinations thereof may be used.

In 100% by weight of the acid mixture, for example, 1 to 40% by weight of the fatty acid may be included, and 50 to 90% by weight of the fatty acid dimer may be included. The monoacid providing the free volume may be included in the acid mixture in an amount of, for example, 1 to 30 parts by weight, or 5 to 20 parts by weight based on 100 parts by weight of the total of the fatty acid and the fatty acid dimer. If the monoacid providing the free volume is used in too small an amount, it is difficult to see the desired effect by using the corresponding component. It may fall off and may cause whitening when immersed in water, and there may also be disadvantages in that the polymerization reaction takes a long time.

The amine used in the preparation of the polyamide curing agent of the present invention is not particularly limited as long as it has one or more (eg, 1 to 8) primary amine groups in the molecule, for example, aliphatic polyamines, aromatic polyamines, cycloaliphatic polyamines and One selected from the group consisting of combinations thereof may be used. Specifically, the aliphatic polyamine is butylamine, dibutylamine, diethylamine, hexylamine, isopropylamine, octylamine, tetrabutylamine, xylidine, aminobenzonitrile, aniline, benzylamine, ethylenediamine, tri It may be selected from the group consisting of methylenediamine, hexamethylenediamine, octamethylenediamine, diethylenetriamine, triethylenetetraamine, pentaethylenehexaamine, and combinations thereof, wherein the aromatic polyamine is orthoxylenediamine, metaxylenediamine, It may be selected from the group consisting of paraxylenediamine and combinations thereof, and the cycloaliphatic polyamine may be selected from the group consisting of isophoronediamine, diaminocyclohexane, 1,3-bisaminomethylcyclohexane, and combinations thereof. have.

The reaction of the acid mixture with the amine may be performed, for example, by adding an amine dropwise to the acid mixture, and raising the temperature of the mixture (eg, to 150 to 250° C.), and the acid value of the reaction product, for example, The reaction may proceed until 1 to 5 mgKOH/g.

A ratio of the total acid equivalents used in the reaction of the acid mixture and the amine to the total amine equivalents may be 1:1.2 to 1:2. If the total amine equivalents are too small compared to the total acid equivalents used, the molecular weight of the reaction product becomes too large, which may limit air spraying due to high viscosity when applied to paints. If too much, the molecular weight of the reaction product becomes too small, which reduces the flexibility of the coating film, and may cause whitening when immersed in water.

As a result of the condensation reaction, imidazoline is produced in the polyamide resin. For example, imidazoline corresponding to 10 to 80 equivalent % of the amine out of 100 equivalent % of the amine added to the reaction with the acid mixture may be produced in the polyamide resin as a result of the condensation reaction. If the amount of imidazoline generated in the polyamide resin is too small, the viscosity of the condensation product may increase, which may limit its use. As a result, the overall physical properties of the coating film may be deteriorated.

The polyamide resin obtained as a result of the condensation reaction may have, for example, an amine value of 150 to 300 mgKOH/g, an active hydrogen equivalent of 150 to 300 g/eq, a specific gravity of 0.9 to 1.1 g/ml, and a viscosity of 5,000 to 20,000 cP And it can exhibit excellent rust prevention and adhesion within the above physical properties range.

The heavy-duty epoxy paint of the present invention includes an epoxy base material and the polyamide curing agent of the present invention described above, and for example, 60 to 80 equivalent% of the polyamide curing agent may be used with respect to 100 equivalent % of the epoxy base material.

There is no particular limitation on the method for preparing the heavy-duty epoxy paint of the present invention, and a known conventional method and apparatus for preparing an epoxy paint may be used.

Hereinafter, the present invention will be specifically described by way of Examples and Comparative Examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereby.

[ Example ]

Example One: polyamide Preparation of hardener

Put 15 g of soybean oil fatty acid, 45 g of soybean oil fatty acid dimer, 55 g of tall oil fatty acid, 5 g of benzoic acid, and 7 g of neodecanoic acid in a 4-neck round bottom flask. 70 g of amine and 30 g of metaxylenediamine were added dropwise. At this time, as the neutralization reaction occurred, the temperature rose to 110°C. As a reflux solvent, 10 g of xylene was added, and the temperature was raised to 140° C. at a rate of 20° C. per hour. When 140°C was reached, effluent from the reaction occurred. After stopping the temperature increase for about 1 hour to remove the effluent, the temperature was raised to 160 °C. When the acid value was maintained at 160° C. and the acid value was between 4 and 5 mgKOH/g, the temperature was slowly raised to 200° C. at the same rate as the previous temperature increase rate to generate imidazoline. As imidazoline was generated, effluent was generated, and when the amount of effluent reached the theoretical value, it was cooled to 130°C. A vacuum pump was installed, the pressure was reduced to a vacuum degree of 700 mmHg, and the remaining effluent was removed by maintaining the pressure for 1 hour to obtain a polyamide curing agent resin. The synthesized polyamide curing agent resin was cooled to 70° C. and the solid content was corrected to 80% by weight. The prepared polyamide curing agent resin had an active hydrogen equivalent weight of 195 g/eq, an amine value of 288 mgKOH/g, a viscosity (Brookfield) of 13,800 cP, and a specific gravity of 0.967 g/ml.

Example 2: polyamide Preparation of hardener

In a 4-neck round bottom flask, 15 g of tall oil fatty acid, 45 g of soybean oil fatty acid dimer, 55 g of tall oil fatty acid, and 12 g of neononanoic acid were placed, and a nitrogen gas pipe, H-type separator, stirrer, thermometer, and heater were installed, followed by 70 g of triethylenetetraamine and 30 g of metaxylenediamine was added dropwise. At this time, as the neutralization reaction occurred, the temperature rose to 105°C. As a reflux solvent, 10 g of xylene was added, and the temperature was raised to 140° C. at a rate of 20° C. per hour. When 140°C was reached, effluent from the reaction occurred. After stopping the temperature increase for about 1 hour to remove the effluent, the temperature was raised to 160 °C. When the acid value was maintained at 160° C. and the acid value was between 4 and 5 mgKOH/g, the temperature was slowly raised to 200° C. at the same rate as the previous temperature increase rate to generate imidazoline. As imidazoline was generated, effluent was generated, and when the amount of effluent reached the theoretical value, it was cooled to 130°C. A vacuum pump was installed, the pressure was reduced to a vacuum degree of 700 mmHg, and the remaining effluent was removed by maintaining for 1 hour to obtain a polyamide curing agent resin. The synthesized polyamide curing agent resin was cooled to 70° C. and the solid content was corrected to 80% by weight. The prepared polyamide curing agent resin had an active hydrogen equivalent weight of 184 g/eq, an amine value of 279 mgKOH/g, a viscosity (Brookfield) of 6,255 cP, and a specific gravity of 0.983 g/ml.

Example 3 and 4, and comparative example 1 to 3: medium meal Application to Epoxy Paint

After applying the polyamide curing agent resin prepared in Examples 1 and 2 as a curing agent to the epoxy base material (Korepox EH2350-PTA, KCC) for anti-rust primer paint for ships, repainting adhesion, urethane top coat adhesion, water whitening resistance , adhesion properties, low-temperature drying properties, rust prevention properties and coating spreadability were evaluated. In Comparative Examples 1 to 3, commercially available curing agents 1) to 3) shown in Table 1 below were used, respectively. The types and contents of each component of the paint, and the measurement results of physical properties are shown in Table 1 below.

1) Ancamide2652: polyamide (polyamide, Air-produnt), 80% solids, viscosity 1850 cP, active hydrogen equivalent 250 g/eq

2) Cardolite2001: phenalkamine (Cardolite, Inc.), solid content 100%, active hydrogen equivalent 125 g/eq

3) Korepox EH2350-PTB: polyamide (KCC), solid content 75%, active hydrogen equivalent 192 g/eq

4) Repainting: After the primer coating, a second coating is performed with the same curing agent at intervals of 5 days to evaluate the adhesion. The longer the repainting period, the better.

5) Room temperature top coat adhesion: Apply a urethane top coat (UT6581, KCC product) to the primer and leave it for 1 day at room temperature (25° C.) to evaluate the relative adhesion.

6) Low-temperature topcoat adhesion: Apply urethane topcoat (UT6581, KCC product) to the primer and leave it at 5°C for 1 day to evaluate the relative adhesion.

7) Water whitening resistance: After immersion of the primer specimen in water at 5° C., relative evaluation was performed by observing gloss and color change compared to before immersion.

8) Adhesion to substrate: After painting the primer on a steel substrate, cross-cut and tap to measure the degree of peeling and evaluate relative.

9) Low-temperature dryness: Measure the drying (solidification) time of the coating film by storing it at 5°C after the primer coating.

10) Anti-rust property: After coating the primer on a metal (Fe) substrate, drying and immersion in a seawater bath at 60°C for 24hrs, measuring the width of peeling off from the cross-cut.

11) Chill spreadability: Visually observe the uniformity of the surface of the resulting coating film after painting/drying the primer on a steel substrate.

From the results of Table 1, the heavy-duty epoxy paint (Examples 3 and 4) to which the curing agent of the present invention is applied has improved repainability compared to the heavy-duty epoxy paint (Comparative Examples 1 to 3) to which the curing agent according to the prior art is applied. , water whitening resistance, top coat adhesion at low temperature, spreadability and rust prevention were all significantly improved.

Claims (4)

As a curing agent comprising a polyamide resin,
The polyamide resin is the result of a condensation reaction between an acid mixture and an amine,
wherein the acid mixture comprises a fatty acid, a fatty acid dimer and a monoacid that provides free volume, wherein the amine has at least one primary amine group in the molecule;
The fatty acid comprises a saturated or unsaturated C14-C28 aliphatic carboxylic acid,
The monoacid providing the free volume is characterized in that it comprises a C3-C12 aliphatic monocarboxylic acid. The monoacid of claim 1 , further comprising the monoacid providing free volume _{selected from the group consisting of C 6} -C ₁₄ aromatic monocarboxylic acids, C ₆ -C ₁₄ aromatic-C ₃ -C ₁₂ aliphatic monocarboxylic acids, and combinations thereof. Polyamide curing agent, characterized in that. The polyamide curing agent according to claim 1, wherein the C3-C12 aliphatic monocarboxylic acid is selected from the group consisting of neononanoic acid, neodecanoic acid, and combinations thereof. The polyamide curing agent according to claim 1, wherein the polyamide resin is obtained by performing a condensation reaction of an acid mixture with an amine until the resultant acid value becomes 1 to 5 mgKOH/g.