KR0139274B1 - Method for manufacturing acrylic modified polyester and coating composition containing the same - Google Patents

Abstract

The present invention relates to a method for producing an acrylic modified polyester resin for powder coating and to a powder coating composition prepared by curing the acrylic modified polyester resin composition, and more particularly, to (1) hydroxyl poly with a mixture of an acid and an alcohol. Preparing an ester prepolymer, (2) solution polymerizing a conventional acrylic monomer with a monomer having an amino or amide group and an acrylic monomer having a carboxyl group to prepare an acrylic resin, and (3) the hydroxyl poly of step (1). Diglycidyl as an acrylic modified polyester and a hardening agent prepared by adding the acrylic resin of step (2) and a divalent or higher polyacid mixture to an ester prepolymer to raise the temperature to prepare a thin acrylic modified polyester resin Ether Bisphenol A Type Epoxy Resin And Titanium Dioxa Draw relates to a powder coating composition comprising.

Description

Manufacturing method of thin acrylic modified polyester resin and powder coating composition containing same

The present invention relates to a method for producing an acrylic modified polyester resin for powder coating and to a powder coating composition prepared by curing the acrylic modified polyester resin composition, and more particularly, using properties of the existing polyester resin and acrylic resin. The present invention relates to a thin powder coating composition prepared by preparing a modified polyester resin and adding an epoxy resin containing bisphenol A as a curing agent to the resin.

Conventional solvent type decorative coating surfaces can produce thin films of 25 to 40 microns thick, but powder coatings used in home appliances are not easy to thin. Recently, a large amount of powder coating is used in home appliances, even if 1 micron thin film thickness is very economic effect. This is outlined in Table 1 below.

<Table 1>

Acidic polyester resins used in conventional polyester-epoxy hybrid thermosetting powder coatings are insufficient due to poor dispersibility and leveling with pigments in order to become thin films. Therefore, in order to manufacture a thin powder coating, the resin must first have excellent dispersibility with the pigment, and in order to form a beautiful coating film, the resin must have a high polarity with high affinity with the pigment and low melt viscosity of the resin itself. However, in the conventional epoxy-polyester (mixed) powder coating, there is a limit in thinning the coating film with a coating film thickness of about 40 to 60 microns. That is, the appearance is not beautiful with low flowability (high melt viscosity) when heated and melted. At this time, if the hardening force is reduced in the molten state, coating is possible in the form of a thin film, but physical properties and solvent resistance are deteriorated. In addition, if the softening point of the paint can be lowered to form a thin film by lowering the melt viscosity, the paint is blocked during storage and poor storage performance. Because of these shortcomings, it was almost impossible to form thin films up to 30 microns with conventional hybrid powder coatings.

Accordingly, an object of the present invention is to improve affinity with the pigment, improve the appearance by having a low melt viscosity while maintaining the desired Tg, and balance the crosslinking reaction rate to achieve good appearance, solvent resistance, chemical resistance, heat resistance and weather resistance An excellent method for producing an acrylic modified pulley ester resin for powder coating.

Another object of the present invention is to provide a powder coating composition containing the acrylic modified polyester resin for powder coating prepared by the above method.

The method of the present invention for achieving the above object comprises the steps of (1) preparing a hydroxyl polyester prepolymer with a mixture of an acid and an alcohol, (2) a monomer having a conventional acrylic monomer and an amino or amide group and an acrylic monomer having a carboxyl group. Solution polymerization to prepare an acrylic resin, and (3) adding the acrylic resin of (2) and a divalent or higher polyhydric acid mixture to the hydroxyl polyester prepolymer of (1) to increase the temperature of the thin film acrylic modified polyester resin. It is composed of the steps of preparing.

The powder coating composition of the present invention for achieving another object of the present invention comprises an acrylic modified polyester resin polymer and a curing agent epoxy resin prepared by the above method.

Looking at the present invention in more detail as follows.

In the present invention, since the conventional polyester resin has a limitation in thinning, select an acrylic monomer containing an amino or amide group having a storage stability (agglomeration resistance) which is basically required in powder coating and excellent dispersion effect and affinity with the pigment, By modifying the synthetic acrylic resin to a polyester resin to improve the chemical resistance and weather resistance, excellent storage properties and to produce a thin film (less than 30 microns).

That is, in the present invention, (1) a hydroxyl prepolymer is prepared from a mixture of an acid and an alcohol, (2) a solution of a conventional acrylic monomer is prepared to produce an acrylic resin, and (3) the acrylic resin is added to the hydroxyl polyester prepolymer. And a divalent or higher polyacid mixture were added to increase the temperature to prepare an acrylic modified polyester resin containing an amide group. In addition, by adding a curing agent and other additives to the acrylic modified polyester resin prepared as described above to prepare a final powder coating excellent in physical properties.

In other words, in the present invention, (I) a hydroxyl polyester prepolymer is first prepared using an acid and an alcohol generally used to prepare a powder coating polyester resin, and an amino or amide group is 2 to 7 weight of an acrylic resin in the resin skeleton. It is prepared in an acrylic prepolymer having a carboxyl group at the end, and then the acrylic prepolymer is reacted with 10 to 50% by weight of the polyester resin and 5 to 20% by weight of the polyacid.The final resin is 1 to carboxyl at the end. It has three, a softening point of 80 to 150 ° C., an acid value of 30 to 100, a number average molecular weight of 2,000 to 10,000, and a polymer structure of a thin film acrylic modified polyester resin having a branched structure or a linear structure. (II) In the case of coating with the resin, a bisphenol A type epoxy curing agent is used as a curing agent of the resin, and a pigment, a flow improver, and other additives are extruded into a mixed extruder, and then ground to a final powder coating. To prepare.

Particularly controlled here is the use ratio of the polyester resin and the acrylic resin. The acrylic resin used has a softening point higher than that of the polyester resin and has excellent thermal flowability, and the acrylic resin tends to exhibit a tendency of acrylic resin up to a certain point in the acrylic / polyester content. It is drastically lowered and the storage property of the paint becomes poor. On the other hand, when the acrylic resin is used a lot, flexibility and mechanical properties may be reduced. Thus, in consideration of the characteristics of each resin to maintain the appropriate balance to have more than complementary physical properties.

Referring to the manufacturing method of the resin according to the present invention in detail,

(A) Preparation of Acrylic Modified Polyester Resin

(1) Preparation of polyester resin (hydroxyl polyester prepolymer)

First, as an acid, dihydric acid or more polyhydric acid is used individually or in mixture, and alcohol also uses dihydric or more polyhydric alcohol individually or in mixture. The acids that can be used are terephthalic acid, isophthalic acid, dimethyl terephthalate, phthalic acid, maleic acid, trimellitic acid, pyromellitic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid or hexahydrophthalic acid and their anhydrides, adipic acid, sebacic acid, ricsinic acid. , Azelaic acid, pyromellitic dianhydride, pivalic acid or cyclo hexadicarboxylic acid, and the like, and preferred acid mixtures are 65 to 90% by weight of paraaromatic diacids including terephthalic acid or dimethyl terephthalate, based on the total acid mixture. , An acid mixture containing 15 to 20% by weight of ortho or metaaromatic acid and 1 to 20% by weight of a linear aliphatic acid having 2 to 8 carbon atoms in a divalent acid having two or more reactive carboxyl groups; And alicyclic or aliphatic alcohols having 2 to 6 carbon atoms and neopentyl glycol and hydroxypivariyl hydroxy pival 60 to 90% by weight of ethylene (eastman trade name: HPHP) and ethylene glycol, diethylene glycol, 1, 3-butanediol, 1, 4-butanediol, 1, 6-hexanediol, 1, 4-cyclohexanediol, trimethyl Using an alcohol mixture composed of 10-40% of one or more selected from the group consisting of all ethane, trimethylol propane and pentaerythritol, the equivalent ratio of alcohol / acid is reacted at 1.1-1.5 and the metal ester catalyst is 0.05. It is used at a temperature of -0.2% by weight to 245 DEG C, and the number average rich amount is 600-3000, the hydroxyl value is 1-2.5 at the terminal, the hydroxyl value is 20-200 mg KOH / g, and the polymer structure is branch or A prepolymer having a linear structure is prepared.

The para aromatic diacid maintains the basic chain of the polyester resin, but when used at 65 wt% or less, the mechanical strength of the resin is lowered, and when used at 90 wt% or more, the resin tends to be too hard. Since ortho or meta carboxylic acid has an influence on crosslinking density and reactivity, 15 weight% or less is preferable, and resin itself becomes too soft when 20 weight% or more of C2-C8 linear aliphatic acid in a diacid is used. The storage property tends to be lowered.

Since the neopentyl glycol and HPHP raw materials are monomers having a neopentyl structure, the reactivity and other physical properties are excellent, but when the weight is 90 wt% or more, the glass transition temperature is increased and the leveling is lowered. However, there exists a tendency for weather resistance and alkali resistance to fall. When the alcohol is added to 10% by weight or less, there is a risk that the body is lowered in flexibility and when the content is 40% by weight or more, the softening point is low, resulting in storage problems.

In addition, when the molecular weight of the hydroxyl prepolymer resin is 600 or less, the softening point is greatly reduced, the storage property is reduced, and at 3,000 or more, the plasticity capacity is lowered and the melt viscosity is not lowered, thereby decreasing the appearance and physical properties of the coating film.

(2) Production of Acrylic Resin

The acrylic resin to be modified in the polyester resin contains amino or amide groups in the resin skeleton, has an acid value of 10 to 150 mg KOH / g, and has 1 to 2.5 carboxyl groups at the end and a number average molecular weight of 500 to 3,000.

If the number of carboxyl groups is 1.0 or less, the acrylic resin addition effect is small. If the number of carboxyl groups is 2.5 or more, the molecular weight is increased more than necessary during the addition (esterification) reaction with the polyester resin, so that the desired resin cannot be obtained. . The number of more preferable carboxyl groups is 1.2-1.8.

Acrylic monomers that can be used in the present invention are roughly divided into the following groups (a), (b) and (c), and firstly (a) copolymerizable equivalents such as methyl (meth) acrylate, ethyl (meth) acrylate, Propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butbutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylic Laterate, tridecyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate , One or more selected from the group consisting of hydroxybutyl (meth) acrylate, 1, 4-butanediol mono (meth) acrylate, and cerusol methacrylate, which may be contained in the total acrylic resin 50-80 weight% of silver is preferable.

The acrylic monomer should be at least 50% by weight to improve adhesion to the base material and have acrylic basic physical properties. When it contains 80% or more, the coating film becomes harder than necessary and the appearance of the coating film may be lowered, more preferably 55 to 75% by weight. In the monomer of the methacrylate type among the above-mentioned monomers, in particular, methyl methacrylate and cellosol moiety acrylate are excellent in compatibility with the polyester resin, and therefore preferably included.

When the methyl methacrylate and cellussolve methacrylate are used in an amount of 50% by weight or more, preferably 60% by weight or more, a particularly excellent gloss and clear coating film can be obtained. In addition, acrylic monomers having long-chain alkyl groups, rather than acryl monomers having short-chain alkyl groups, increase the compatibility, reduce cretaring on the surface of the coating film, and smooth the coating film.

Methyl (meth) acrylate in this compound means methyl methacrylate and / or methyl acrylate.

(b) The monomers belonging to the group consisting of acrylic acid or methacrylic acid, maleic acid, fumaric acid, itaconic acid and maleic anhydride are preferably used in an amount of 5 to 25% by weight based on the total acrylic resin. When less than 5% by weight is used, there is little addition effect to acrylic and polyester, and the acrylic resin acts as a plasticizer in all the polymer components, thereby lowering the mechanical properties of the coating film. If more than 25% by weight is used, the crosslink density with the polyester resin is high and the melt viscosity is high before the coating film is formed. Therefore, the appearance of the film is poor. These monomers not only increase the compatibility with the polyester resin but also improve the weather resistance, Improves hardness and rust prevention. A more preferable ratio is 5-20 weight%.

(c) Monomers having an amino or amide group in the acrylic resin backbone include n, n-dimethylamino ethyl methacrylate, n, n-dimethylamino ethyl methacrylate, dimethyl amino ethyl methacrylate quaternary, acryl Amides, methacrylamides, n-methylol acrylamides, methylol methacrylamides, or diacetone acrylamides form an anchoring group, which increases the mobility of the resin by entering -N-group into the resin bone. It is preferable to use as a dispersant of the resin, and the amount of use is 2 to 7% by weight based on the total acrylic resin, and the dispersing effect, leveling, and compatibility are improved as the amount of use is increased, but when using more than 7% by weight, yellowing of the resin It gets harder, so it is difficult to produce white when painting. In addition, when used at 2% by weight or less, the affinity with the pigment is weakened, the dispersing effect during the production of the paint is reduced, the hiding power is lowered when the paint is thinned.

Other copolymerizable monomers include, for example, styrene, alpha-methyl styrene vinyl toluene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, vinyl chloride, ethylene, propylene or C4 to C20 alpha-olefins. Can be mentioned.

As a method of solution-polymerizing the acrylic monomers into an acrylic resin, any one of conventional methods such as solution polymerization, suspension polymerization, bulk polymerization, or emulsion polymerization may be used, but solution polymerization is most commonly used. desirable.

Initiators used in the present invention include azo compounds such as azobis isobutyronitrile or azo bisdimethylmethyl valeronitrile, but benzoyl peroxide, tertiary butyl hydroxide, tertiary butyl peroxy benzoate, and dibutyl butyl Peroxide organic initiators such as peroxide, cumenehydro peroxide, dicumyl peroxide or lauroyl peroxide can be used. As a solvent, an aliphatic or aromatic hydrocarbon solvent or a monoalcohol solvent having a polar group such as nomal-butane may be used, and the isothermal reaction may be carried out depending on reflux or which raw material is used. The final resin is removed under reduced pressure at 30 mmHg or less.

In addition, in the present invention, in order to prevent the molecular weight from being increased more than necessary, a polymerization regulator of a mercurtan system may be used, and as the regulator, n-butyl mercuptane, n-amyl mercurtan, n-dodecyl mercurtan, tertiary Boomercup shots or 3-epoxy propyl mugcup shots and the like are used.

(3) Production of Acrylic Modified Polyester Resin

To the polyester resin (hydroxyl prepolymer) prepared in step (1), the acrylic resin prepared in step (2) is used in an amount of 10 to 50 parts by weight based on 100 parts by weight of the polyester resin and a divalent or higher polyvalent acid mixture. 5 to 20 parts by weight with respect to 100 parts by weight of the polyester resin together with the reaction temperature is raised to 220 ℃ until the reaction water does not come out the number of carboxyl groups at the end of 1 to 3 and the acid value 30 ~ 100mg KOH / g softening point is 80 ~ 150 degreeC and the number average molecular weight manufacture the acrylic modified polyester resin of 2,000-10,000.

The polyacid mixtures used in the present invention comprise 20 to 70% by weight of trivalent or more aromatic acids, 30 to 80% by weight of divalent ortho or metaaromatic acids and linear aliphatic acids. Same as mentioned in When the trivalent or higher acid is used at 20% by weight or less, the desired carboxyl group number is hardly generated in the final resin, and the crosslinking density is low in the final paint, thereby deteriorating physical properties. In the case of more than 70% by weight, a polymer having a molecular weight of more than necessary is generated, and as the thermal flowability is lowered, the appearance of the coating film becomes poor and even wrinkles or pinholes are caused, making it difficult to thin the film. When divalent ortho or metaaromatic and linear aliphatic acid is used at 30 wt% or less, the melt viscosity of the resin is lowered, the flexibility is lowered, the flexibility is poor, and the mechanical properties are also lowered. When used at 80% by weight or more, not only the hardness of the coating film is lowered, but also the storage stability of the paint is poor.

When the acrylic resin is modified to 10 parts by weight or less with respect to 100 parts by weight of the polyester resin, the physical properties of the acrylic resin do not appear, meaning that there is no change in affinity and the affinity with the pigment is lowered. The thermal flowability of the film deteriorates, resulting in poor appearance of the coating film. More preferred amount is 15 to 40% by weight.

(B) Preparation of Powder Coating Composition

It is essentially composed of 20-50% by weight of the acrylic modified acidic polyester resin prepared in step (a), 20-50% by weight of epoxy resin and 20-60% by weight of titanium dioxide as a curing agent, and a curing accelerator and other additives (flow Property improver, antioxidant, and ultraviolet absorber), and then, mixed in the above mixing ratio, passed through an extruder, and then ground to prepare a powder coating.

Epoxy resins used as curing agents were epicode 1002, 1003, 1004, 1005 (product name of Shell) of diglycidyl ether bisphenol A type as a polymerization product of bisphenol A and epichlorohydrin having an equivalent weight of about 600 to 1,000. The amount of the compound is adjusted according to the acid value of the acrylic modified polyester resin and the equivalent of the epoxy resin, but the equivalent ratio of the epoxy acid polyester resin is 1.0 to 1.15 so that the epoxy resin is slightly excessive. In addition, as a flow improving agent, Modaflow I (Monsanto), FV-5 (worlee) or Acronal 4-F (BASF) may be used. As a stabilizer, Iraganox-1076 (Shibagai Iisa) ) Can be used.

Curing accelerators that can be used in the present invention include quaternary ammonium salts such as tetra methyl ammonium bromide or tertiary amines, amidazoles, organotin compounds such as triphenyline collide or butyl tin laurate.

The powder coating composition of the present invention prepared through the steps (A) and (B) has a lower curing temperature than that of a conventional acidic polyester-epoxy system (hybrid) or conventional acryl at 30 ° C. at 30 ° C. Even 20 minutes of curing reaction at minutes or 160 ℃ exhibits the same mechanical properties as the epoxy paint, that is, impact, flexural properties, erit. In addition, the heat resistance and weather resistance exhibit excellent properties compared to the conventional hybrid type, (2) the copolymer of the acrylic copolymer containing a linear polyester resin and amino or amide groups is 10 parts by weight of acrylic resin It has a softening point that is almost similar to acrylic resin itself by modifying it to -50 parts by weight, and shows a low value of melt viscosity. It has excellent storage properties even at 35 to 40 ° C, and has excellent thermal flowability, resulting in a smooth and glossy surface. (3) Low melting As it has excellent viscosity and heat flow during film formation, it has excellent general properties and excellent glossiness and appearance and glossiness, even with thinners of 25 to 40 microns, such as solvent type, having the curing power and storage stability necessary for curing. .

Hereinafter, the present invention will be described in more detail with reference to Preparation Examples and Examples, but the scope of the present invention is not limited to the following Examples.

[Production Example 1]

Hydroxyl polyester resin 1 (hereinafter referred to as Paul-1).

Into an alcohol mixture of 1500 g of telephthalic acid, 100 g of isophthalic acid, 80 g of adipic acid, 800 g of neopentyl glycol, 420 g of HPHP, and 420 g of ethylene glycol, 160 g of ethylene glycol, 2 g of Fesket-4101 (MT) was added to prevent the axial function from coming out of nitrogen. It heated up to 230 degreeC until it manufactured hydroxyl polyester. The polyester resin had a number average molecular weight of 1300 and a hydroxyl value of 60.

[Production Example 2]

Hydroxyl polyester resin 2 (hereinafter referred to as Paul-2).

1000 g of dimethyl telephthalate, 100 g of adipic acid, 600 g of neopentyl glycol, 300 g of HPHP, and 170 g of ethylene glycol were added, and the reaction mixture was heated to 210 ° C. while removing methanol using 0.5 g of zinc acetate as a catalyst. After cooling, 50 g of succinic acid and 120 g of isophthalic acid were reacted, and 2.0 g of dimethyltin oxide was added thereto, followed by heating to 230 ° C., thereby preparing a hydroxyl polyester resin. The number average molecular weight of the resin is 1400 and the hydroxyl value is 50.

[Manufacture example 3]

Hanedoxyl Polyester Resin 3 (hereinafter referred to as Paul-3).

Dimethytephthalate 820g, neopentyl glycol 500g, HPHP 290g, ethylene glycol 130g, 1, 6- hexanediol 78g, trimethylolpropane 50g during the transesterification reaction, the zinc acetate 1.8g as a catalyst and the temperature is raised to 210 ℃ To remove methanol. After cooling to 120 ° C., 175 g of sebacic acid and 400 g of isophthalic acid were reacted, and the reaction mixture was heated to 230 ° C. using 1.0 g of dibutyltin oxide as a catalyst to prepare a hydroxyl polyester resin. The number average molecular weight of the resin is 1600 and the hydroxyl value is 45.

[Production Example 4]

Hydroxyl polyester resin 4 (hereinafter referred to as Paul-4).

1002 g of telephthalic acid, 105 g of isophthalic acid, 115 g of adipic acid, 48 g of azaline acid, 650 g of neopentyl glycol, 650 g of HPHP, 76 g of ethylene glycol, 73 g of cyclohexane dimethanol and 2.3 g of dibutyltin oxide until no condensation water came out It heated up to 230 degreeC and manufactured the hydroxyl polyester resin. The polyester resin has a number average molecular weight of 1300 and a hydroxyl value of 55.

Production Example 5

Acrylic resin 1 (hereinafter referred to as A-1).

253 g of methyl methacrylate, 46 g of methacrylic acid, 23 g of methacrylamide, 138 g of n-butyl acrylate, 9 g of azobis isobutyronitrile as an initiator were dropped into a solvent of 200 g of toluene and 300 g of n-butanol over 3 hours. After refluxing for 2 hours, 0.5 g of benzoyl peroxide was added to 25 g of toluene, and then reacted for 2 hours. Secondly, 0.5 g of benzoyl peroxide was added to 25 g of toluene, followed by reaction for 3 hours. Toluene and butanol were removed under reduced pressure of 300 mmHg or less by raising the temperature to 160 to 170 ° C to prepare an acrylic resin. The acid value of the said resin is 65 mgHOH / g, and the number average rich weight is 1200.

[Manufacture example 6]

Acrylic resin 2 (hereinafter referred to as A-2).

400 g of methyl methacrylate, 100 g of acrylic acid, 50 g of acyl amide, 300 g of 2-ethylhexyl acrylate, 150 g of styrene, 10 g of tertarybutyl peroxyoctane as an initiator, and 3 g of n-dodecyl mugtantan as a polymerization regulator The mixture was mixed with the solvent dropping over 1200 g of n-butanol over 3 hours, and the subsequent method was carried out in the same manner as in Preparation Example 5 to prepare an acrylic resin. The acid value of the resin was 78 mg / KOH / g and the number average molecular weight was 1300.

[Manufacture example 7]

Acrylic resin (hereinafter referred to as A-3).

400 g of methyl methacrylate, 64 g of methacrylic acid, 56 g of dimethylaminoethyl methacrylate, 200 g of n-butyl acrylate, and 80 g of styrene were mixed, and 2.5 g of benzyl peroxide was 1.6 g of n-decyl merethane. The mixture was dropped and reacted to 1300 g of toluene over 3 hours, and then the method was performed in the same manner as in Preparation Example 5 to prepare an acrylic resin. The acid value of this resin is 52 mgKOH / g and the number average molecular weight is 1200.

[Manufacture example 8]

Acrylic resins (hereinafter referred to as A-4).

264 g of methyl methacrylate, 62 g of acrylic acid, 53 g of dimethylamino ethylmethacrylate, 264 g of ethyl methacrylate, and 238 g of hydroxy ethyl acrylate were mixed, 3.0 g of benzyl peroxide and n-dodecyl merethane with polymerization regulator 1.8 The mixture was mixed by dropping to 1250 g of toluene over 3 hours, and then the method was carried out in the same manner as in Preparation Example 5 to prepare a resin having a number average molecular weight of 1100 and an acid value of 54 mgKOH / g.

EXAMPLES 1-8

The acrylic modified polyester resin was prepared by the above-mentioned method by combining the polyester resins prepared in Preparation Examples 1 to 4 and the acrylic resins prepared in Preparation Examples 5 to 8 with the polyhydric acids shown in Table 2 below. . While reacting, the polymerization reaction was performed until no condensed water was produced, thereby preparing a resin having a desired physical property. The physical properties of the acrylic modified polyester resin thus prepared are shown in Table 3 below.

<Table 2>

<Table 3>

EXAMPLES 9-16

The resins of Examples 1 to 8 correspond to Examples 9 to 16, respectively, and were formulated in the composition shown in Table 4 below to prepare powder coating using a conventional coating method, and 0.7 mm hemp pretreated with zinc phosphate. The coated steel sheet was cured at 180 ° C. for 10 minutes to prepare a coating having a thickness of 30 ± 5 μm, and the physical properties thereof are described in Table 5 below.

<Table 4>

Comparative Example 1

Acidic polyester resin 1

Acid mixture of 1500 g of telephthalic acid, 100 g of isophthalic acid, 80 g of adipic acid, 1015 g of neopentyl glycol, and 200 g of ethylene glycol were heated to 230 ° C. using dibutyltin oxide as a catalyst to prepare a prepolymer, followed by trimellitic anhydride. An acidic polyester resin having a carboxyl group at the end was prepared using 270 g of lead and 120 g of idipic acid. The resin had a number average molecular weight of 2700 and an acid value of 70 mm KOH / g and a softening point of 118 ° C.

Comparative Example 2

Acid polyester resin 2

After preparing a prepolymer by heating an acid mixture of 1500 g of telephthalic acid, 148 g of adipic acid, 1092 g of neopentyl glycol, and 120 g of 1, 6-hexanediol, 2.5 g of dibutyltin oxide was used as a catalyst to prepare a prepolymer, followed by trimellitic anhydride. An acidic polyester resin having a carboxyl group at the end was prepared using 300 g of lead and 140 g of succinic acid. The number average molecular weight of the resin was 3000, the acid value was 76 mm KOH / g, and the softening point was 117 ° C.

Comparative Example 3

Acidic polyester resin 3

After heating up to 230 ° C using 1050 g of telephthalic acid, 450 g of isophthalic acid, 80 g of adipic acid, 1040 g of neopentyl glycol, 1040 g of trimethylol propane, HPHP 136 g, ethylene glycol 50 g, and dibutyltin oxide as catalysts, An acidic polyester resin having a carboxyl group at the terminal was prepared using 300 g of hydride and 132 g of cyclohexanedicarboxylic acid. The resin had a number average molecular weight of 2600 and an acid value of 60 mm KOH / g and a softening point of 116 ° C.

To prepare a paint using the resins of Comparative Examples 1 to 3 Comparative Example 1 is a paint formulation of Example 9 Comparative Example 2 is a paint formulation of Example 15, Comparative Example 3 is a paint formulation of Example 13 Was prepared and coating and curing were carried out in the same manner as in Example. Coating properties of the resins are shown in Table 5 below.

Claims (9)

(1) preparing a hydroxyl polyester prepolymer with a mixture of an alcohol having an equivalent ratio of alcohol / acid of 1.1 to 1.5, (2) from 50 to 80% by weight of a conventional acrylic monomer and monomers 2 to 7 having amino or amide groups Solution polymerization of the acrylic monomer having 5% to 25% by weight and 5% to 25% by weight of a carboxyl group and (3) the acrylic resin of the step (2) and the dihydric acid in the hydroxyl polyester prepolymer of the step (1) The above-mentioned polyacid mixture is added to increase the temperature to react, and has 1 to 3 carboxyl groups at the end, the acid value is 30 to 100mg KOH / g, the softening point is 80 to 150 ℃ and the number average molecular weight is 2,000 to 10,000 polyacryl modified poly Method for producing a thin film acrylic modified polyester resin, characterized in that consisting of steps of preparing an ester resin. The acid according to claim 1, wherein the acid of step (1) is 65 to 90% by weight of para aromatic acid including kerephthalic acid or dimethyl terephthalate, 15% by weight to ortho or metaaromatic acid, and two carboxyl groups. It is an acid mixture which consists of 1-20 weight% of linear aliphatic acids of 2-8 carbon atoms in a diacid, The manufacturing method of the thin film acrylic modified polyester resin characterized by the above-mentioned. The method for producing a thin film acrylic modified polyester resin according to claim 2, wherein the linear aliphatic acid having 2 to 8 carbon atoms is selected from the group consisting of adipic acid, lactic acid, sebacic acid and azeline acid. . According to claim 1, wherein the alcohol mixture of step (1) is composed of 60 to 90% by weight of neopentyl glycol and hydroxy pivariyl hydroxy pivalate and 10 to 40% by weight of a dihydric or higher polyhydric alcohol. Method for producing a thin film acrylic modified polyester resin. The method of claim 4, wherein the divalent or higher polyhydric alcohol is ethylene glycol, diethylene glycol, 1, 3-butanediol, 1, 4-butanediol, propylene glycol, 1, 6-hexanediol, trimethylolpropane, trimethylol A method for producing a thin film acrylic modified polyester resin, characterized in that at least one selected from the group consisting of ethane, pentaerythritol and 1,4-cyclohexanediol. The thin film-type acrylic modified polyester according to claim 1, wherein the acrylic monomer used in the production of the acrylic resin in step (2) is essentially selected from the following groups (a), (b) and (c). Method for producing a resin. (a) methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, tridecyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, hydro One or more thereof from the group consisting of cyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 1, 4-butanediol mono (meth) acrylate and cerusol methacrylate At least one compound selected from copolymerizable acrylic monomers, (b) monomers consisting of acrylic acid, metaacrylic acid, maleic acid, fumaric acid, itaconic acid and maleic anhydride And (c) dimethylamino ethylmethacrylate, dimethylamino ethylmethacrylate, dimethylamino ethylmethacrylate quaternary cargo, acrylamide, methacrylamide, n-methyl as monomers containing amino or amide groups. At least one mixture selected from monomers consisting of allacrylamide, methylolmethacrylamide and diacetone acrylamide The thin film type according to claim 1, wherein the polyacid mixture of step (3) comprises 20 to 70% by weight of trivalent or more aromatic acid and 30 to 80% by weight of divalent aromatic or linear aliphatic and alicyclic acid. Method for producing acrylic modified polyester resin. According to claim 1, wherein the acrylic modified polyester of step (3) is 10 to 50 parts by weight of the acrylic resin and (5) parts by weight of polyvalent to 100 parts by weight of the polyester resin of step (1) Method for producing a thin film acrylic modified polyester resin, characterized in that consisting of an acid mixture. 20 to 50% by weight of an acrylic-modified polyester resin prepared by the method according to claim 1 comprising 20 to 50% by weight of diglycidyl ether bisphenol A type epoxy resin equivalent to 600 to 1000 and 20 to 60% by weight of titanium dioxide. Powder coating composition characterized in that it is wet.