KR19980044370A - Low Temperature Small Transparent Topcoat Composition - Google Patents

Abstract

The present invention is to prepare a urethane polymer by reacting an amine compound with an alkylene carbonate (Carbonate) compound, and reacted with one or more isocyanate compounds to produce a urethane oligomer having four or more hydroxyl groups 4 80 to 20% by weight of the urethane oligomer having at least two hydroxyl groups and 20 to 80% by weight of an acrylic resin, urethane, alkyd, ester, epoxy resin or a copolymer thereof or a mixture of two or more by using a water dispersion resin composition The present invention relates to a water-based transparent topcoat composition, which may be applied as a small transparent topcoat for automobiles, forms a high gloss coating, and is excellent in acid, water, chipping, and scratch resistance.

Description

Low Temperature Small Transparent Topcoat Composition

The present invention relates to a low-temperature baking type transparent topcoat composition suitable for automotive waterborne top coats, comprising: a method for producing a urethane oligosaccharide having four or more hydroxyl groups induced by the reaction of an alkylene carbonate and a polyamine, and a water containing the same The present invention relates to a dispersion resin composition and a one-component transparent top composition containing a curing agent and other additives in the composition.

In order to cope with the growing environmental regulations all over the world, the development of a new system for reducing the environmental regulations is being actively developed. Among them, high solids, water-borne and powder systems are widely gaining popularity. High solids and waterborne systems have long been studied and are known to reach significant levels in electrodeposition, intermediate, top coat and clear coatings.

The two functions of automobile painting are beautiful appearance and material protection. The beautiful appearance of the coated film is determined by the degree of heat flow and volume shrinkage during the drying process of the paint. In order to improve the appearance of the coating film, sufficient heat flow is required before curing. If hardening occurs in a state in which heat flow is insufficient, the leveling is bad and an excellent appearance cannot be expected. In order to induce sufficient heat flow during the drying process, the molecular weight of the main resin is lowered or co-solvents are often used. However, the low molecular weight of the main resin is poor in the physical properties of the coating film and the use of the coarse solvent is a severe volume shrinkage of the coating film due to the volatilization of the solvent during the curing process, there is also a limit in improving the leveling.

Recently, an example of improving leveling by mixing a low molecular weight polymer with a high molecular weight aqueous dispersion has been published. For example, German Patent No. 3910829 refers to a water soluble polyester oligomeric polyacrylic resin, which is said to obtain a clear coating with high gloss and good appearance.

In German Patent No. 202072, an oligomeric polyester having a molecular weight of about 200 is mixed with an acrylic resin, but this system is not applied to an aqueous system.

German Patent No. 3537855 mentions a condensation reaction product of an acrylic resin and a polyether polyol, which is known to have poor acid and water resistance due to hydrophilic polyether.

European Patent Application No. 365775 mentions a system for neutralizing and dispersing an acrylic resin having a carboxyl group (Carboxyl) and adding a hydrophilic melamine resin. However, no mention is made of the use of hydrophilic melamine and blocked isocyanate.

Canadian Patent 2100493 mentions a brand of an acrylic resin having a carboxyl group and a hydroxyl group (Hydroxyl) and a polyester oligomer having a hydroxy group, and further mentions a brand of melamine and a block isocyanate.

The present invention relates to a coating composition prepared by using a water dispersion resin containing a urethane oligomer exhibiting good compatibility regardless of the type of resin and showing improved physical properties. It has a radically different form. Existing patents control the viscosity and physical properties by branding or copolymerizing a diol ester resin in main resins such as acrylic and urethane. They will have two to three curing functional groups when cured with melamine or isocyanates. However, the urethane oligomer of the present invention can introduce at least four or more hydroxy functional groups, and these act as a curing functional group to increase the curing density to satisfy the required physical properties of automotive coatings.

In addition, the existing patents mainly refer to the ester oligopoly with good compatibility with acrylic resin, and generally urethane is avoided due to poor compatibility with acrylic. However, the urethane oligomer of the present invention has a low viscosity, has an appropriate glass transition temperature, and exhibits good compatibility regardless of resin types such as acrylic resins, alkyd resins, and urethane resins due to high hydroxyl value.

In the preparation of water-dispersible resins, it is generally not possible to form stable water products unless a hydrophilic chain is introduced into the resin backbone. Therefore, in the production of water-based acrylic resin alone, a suitable combination of mono- and water-soluble properties is required, or a large amount of carboxyl group is introduced as a neutralizing functional group or a monomer having a hydroxy group is introduced to improve compatibility with water. do. However, this method has a disadvantage in that a large amount of solvent is required to make a high viscosity resin. In addition, a large amount of carboxyl groups results in poor water resistance of the coating film. In addition, the introduction of the hydrophilic acrylic monomer does not satisfy the water resistance and other physical properties.

As a result, the introduction of the hydrophilic chain into the main resin may have a good result on the dispersion stability, but may adversely affect the physical properties of the final coating. Urethane oligosaccharide of the present invention can compensate for the weak points when dispersing the main resin. For example, a stable dispersion can be produced by mixing about 3 to 30% by weight of a hydrophobic acrylic resin which is not water-dispersible alone.

In terms of physical properties, ester oligomer resins in the existing patents have poor results in water resistance and acid resistance. However, in the present invention, the urethane oligomer has four or more hydroxyl groups per molecule and thus forms a urethane bond, thus showing superior physical properties compared to the ester bond. In addition, when used in combination with the acrylic resin, it increases the flexibility of the coating film serves to compensate for the weak impact resistance of the acrylic resin itself.

The present invention essentially relates to a composition prepared using a water-dispersible resin containing a urethane oligomer having four or more hydroxyl groups obtained by the reactions mentioned below. The preparation of the urethane oligomers of the present invention is obtained by a nonisocyanate process, the specific method of which is as follows. That is, the amine compound represented by the following formula (I) is reacted with an alkylene carbonate (Carbonate) compound represented by the following formula (II) to prepare a urethane polymer represented by the following formula (III), and to react one or more isocyanate compounds Urethane oligomers having four or more hydroxyl groups are prepared.

[Formula I]

H ₂ NR ₁ -NH-R ₁ -NH ₂

In the above formula, R ₁ is an alkyl group having an ethyl group or a propyl group and the like, and there are diethyltriamine and dipropylenetriamine.

[Formula II]

In the formula, R ₂ is an alkyl group having 1 to 6 carbon atoms.

[Formula III]

Wherein R ₁ and R ₂ are as described above.

For example, when polymerizing propylene carbonate in which R ₂ is CH ₃ with R ₁ diCH ₃ indiethylene triamine, a polymer of formula IV is obtained by reaction of one diethylene triamine and two propylene carbonates. At this time, the reaction proceeds at 40 ° C. under no catalyst.

[Formula IV]

An amine at the end of the triamine chain attacks the carbonate ring to form a urethane bond. This polymer has two hydroxyl groups in the chain end and one -NH group in the main chain, forming two urethane bonds. This polymer is used as an oligomer and shows good compatibility when mixed with other resins (acrylic, ester, urethane), and two hydroxyl groups and one -NH group act as reaction functional groups with melamine or isocyanate.

In this invention, the isocyanate was introduce | transduced into this polymer, and the oligomer which has 4-6 hydroxyl groups was applied. For example, the reaction of NCO of diisocyanate with the -NH group of the above polymer yields a polymer represented by the following formula (V), and proceeds without catalyst at a temperature of 50 ° C. or lower. The reactivity of the isocyanate with the hydroxy group proceeds at a temperature of at least 80 ° C., but the reactivity with -NH proceeds faster than the hydroxy group. Identification of this reaction polymer was verified by measurement of the content of NMR, IR, and hydroxyl groups.

[Formula IV]

The polymer has four OH groups at the sock end and six urethane bonds. It is also possible to prepare compounds having six hydroxyl groups at both ends by reaction with trifunctional NCOs in the trimer or biuret form of isocyanates. This material is called 6-XLR.

Reactivity with isocyanates must react below 50 ° C to selectively react with amines. These polymers can produce polymers of different physical properties according to the amount with isocyanate and can be adjusted according to the usability and the use physical properties with other resins. Generally, it has a glass transition temperature of -50 to 20, preferably -20 to 10, and has a hydroxyl value of 50 to 600 mgKOH / g, preferably 100 to 500 and a number average molecular weight of 300 to 5000.

Isocyanates having a structural formula of OCNRNCO include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and 4,4-diphenylmethane diisocyanate. Isocyanate (4,4-diphenylmethane diisocyanate), 1-methyl-2,4-cyclohexane diisocyanate (1-methyl-2,4 cyclohexanae diisocyanate). 1-methyl-2,6-cyclohexane diisocyanate (1-methyl-2,6-cyclohexanae diisocyanate), 1-isocyanato 3,3,5 trimethyl 3 methyl cyclohexane isocyanate (1-isocyanto-3,3 , 5-trimethyl-3-methyl-cyclohexane isocyanate, 4,4-diisocyanato dicyclo hexyl methane, hexamethylene diisocyanate, m-xyylene diisocyanate (m-xylylene diisocyanate), p-xylylene diisocyanate, tetramethyl xylylene diisocyanate, tetramethyl diisocyanate, isophorone diisocyanate, Cyclohexanae-1,4-diisocyanate. Suitable mixtures of these isocyanates may also be used, and trifunctionals in the form of trimers or biurets of diisocyanates may also be used.

As the polymerization solvent, a solvent which can be dissolved or mixed in water is used, for example, monohydric aliphatic alcohol (ethanol, isopropanol) having 2-4 carbon molecules, trivalent butanol and trivalent amyl alcohol. Alcohols, acetone, ketones such as methyl ethyl ketone, dimethyl ether of ethylene glycol, methyl glycol, butoxy ethanol, methoxy propanol ethers such as propanol), methoxy propxy propanol, glycol ethers of various diols, and the like, and ethylene glycol, diethylene glycol, and propylene glycol can be used. Acetates of ethers may be used, for example ethylene glycol ethyl ether acetate, ethylene glycol propyl ether acetate, ethylene glycol butyl ether Acetates, diethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol butyl ether acetate and the like. In addition, a solvent that does not contain an alcohol group and is hydrophilic may be used. Examples thereof include acetone, methyl ethyl ketone, and ene-methylpyrrolidone (NMP). In addition, solvents which are insoluble or insoluble in water may also be used in part. In addition, solvents which are insoluble or insoluble in water may also be used in part, and suitable mixtures of the above solvents may be mixed and used. The content of the organic solvent contains 10 to 60% by weight, preferably 20 to 50% by weight.

Water dispersion resin composition containing a urethane oligomer having four or more hydroxyl groups applied for another object of the present invention resin 80 to 20% by weight of the urethane oligomer having four or more hydroxyl groups prepared by the above method and acrylic as main resin , Urethane, alkyd, esters, epoxy resins or copolymers thereof or mixtures of two or more thereof.

The synthesis method of this water-disperse resin can be divided into two classes. One is a process for producing a resin in the form of an aqueous dispersion, and the other is a solvent type for polymerizing using a hydrophilic solvent as a polymerization solvent. In the case of the water dispersion type, it is polymerized using a hydrophobic solvent or a hydrophilic solvent, and it is water-reduced after being removed under reduced pressure.

A hardener may be included in the aqueous product, in which case, the hardener may be a block isocyanate and an amino resin or a mixed resin of these two resins. The type of blocked isocyanate or amino resin can be applied differently depending on the required physical properties of the coating film. Generally, the coating film to which the amino resin is added excessively is used in combination with a block isocyanate because it is weak in acid resistance. When other amino resins that improve acid resistance, ie, butylated amino resins, are used, the acid resistance is improved compared to methylated amino resins.

When the curing agent is mixed with the water dispersible resin, the shape of the final water dispersant largely depends on whether or not the form of the curing agent is dissolved in water. In the case of a water-soluble or dispersible curing agent, it is easy to mix with an aqueous product and thus may be added at the time of preparing the paint. However, if the property of the curing agent is hydrophobic and insoluble in water, it may be added before the preparation of the aqueous dispersion. Determining the order of addition of the curing agent has a strong correlation with the final viscosity of the water dispersion. Generally, hydrophobic curing agents are added before the water dispersion and hydrophilic curing agents are preferably added before or after the water dispersion. Urethane oligomers applied to the present invention can improve the disadvantages of the water dispersion process in the existing patent as described above. After mixing the hydrophobic resin or the curing agent, the urethane oligomer is added to neutralize the mixture and neutralized. After the neutralization, the urethane oligomer is mixed to disperse the water or mixed with the main resin to mix and disperse the hydrophilic curing agent. In this case, a low molecular weight, hydrophilic urethane oligomer greatly improves the dispersibility, a very stable and low viscosity water dispersion is obtained. The ester oligomer method in the existing patent is difficult to apply due to the high viscosity of the application of the hydrophobic resin or hardener, and as a result, it is forced to add a large amount of solvent or lower the solid content.

When superposing | polymerizing using a hydrophilic solvent, it is not necessary to remove a solvent at reduced pressure. When the resin is used in a form dissolved in a hydrophilic solvent, both the form of the curing agent and the form dissolved in the hydrophilic solvent can be applied. However, when using a water-dispersible resin, the curing agent dissolved in the solvent is inconvenient to be mixed before the water dispersion.

When coating the resin on the hydrophilic solvent, first neutralize the resin with an amine, add an additive for supplementing physical properties, add a curing agent, and finally add water to prepare an aqueous dispersion paint. This method is simple and economical because it does not require a decompression process and a pre-water dispersion of the curing agent than when manufacturing a coating using a water dispersion resin.

As the main resin, resins such as acrylic, urethane, alkyd, ester, epoxy, etc. may be applied depending on the properties of the coating film, and it is preferable to use a polymer having a carboxyl group and a hydroxyl group, and acrylic, urethane, ester, epoxy polymer or Copolymers thereof or mixtures of two or more thereof may be used.

These polymers contain 20 to 80% by weight, preferably 30 to 60% by weight, to form an aqueous dispersion.

Usually these resins contain about 50 to 10% of solvents because they are made by solution polymerization. In the case of producing the water dispersion resin, when these solvents are not removed, it is easy to mix with additional resins (curing agents, etc.), but the viscosity of the final water dispersion becomes high, and as a result, a diluent solvent is required in the preparation of the paint. Therefore, it is usually preferable to remove the solvent under reduced pressure. After removal of solvent pressure, the solid content of the resin is almost 100% and the viscosity is also large. This high viscosity resin is not a big problem when the temperature is high, but the dispersibility is remarkably poor when the temperature is below 80 ℃ due to the considerable high viscosity. In this solution, it is preferable to add 1 to 20% of a hydrophilic solvent, but there is a disadvantage in that the content of volatile organic compounds (VOC) is increased. When adding a low boiling point solvent, it is possible to remove a solvent by depressurizing after water dispersion. For example, solvents of 100 ° C. or less may be used, such as acetone and methyl ethyl ketone (MEK).

As mentioned above, as a solution to the high viscosity of the main resin can be solved by using a hydrophilic solvent to remove the decompression process, but the disadvantage may be a high solvent content in the resin.

The urethane oligomer of the present invention is capable of producing low viscosity, low glass transition temperature and low molecular weight, and also has high hydrophilicity due to high hydroxy value, thereby eliminating the need for a solvent for viscosity control when mixed with a main resin.

When using a hydrophobic solvent, the water-dispersion method is 0 to 10%, preferably 0 to 5% of the residual solvent after reduced pressure, and neutralized with trivalent amine after reduced pressure. The urethane oligomer is added before or after neutralization and stirred to complete mixing. At this time, a suitable solvent may be added to lower the viscosity of the polymer in the stirrer and to facilitate mixing between the resins. Thereafter, ion-exchanged water is gradually added to disperse the water, or the resin is added to the ion-exchanged water with a high speed stirrer to disperse the water. As described above, the water-dispersible resin composition containing the urethane oligomer having four or more hydroxyl groups applied to the present invention was based on a patent filed by Korea Chemical Co., Ltd. (Application No. 95-69631).

When the water-soluble one-component transparent topcoat composition is an object of the present invention to prepare a water-soluble one-component transparent topcoat composition by applying the water-dispersible resin composition prepared above, 40 to 70% by weight of the water-soluble resin composition in the total water-soluble paint composition, It consists of 15 to 35 weight% of hardeners, 3.2 to 11.5 weight% of additives, and 4 to 15 weight% of a coarse solvent.

The antifoaming agent applied to the water-soluble one-component transparent topcoat composition of the present invention is a mineral oil-free non-silicone-based antifoaming agent, which is added to solve the phenomenon of the coating as well as the problem of cratering and popping. The amount is preferably 0.5 to 3% by weight based on the total water-soluble paint composition.

In addition, in the paint composition of the present invention, wetting and coating film is formed when the paint is on the base material, and polysiloxane-based additives (wetting agent, leveling agent) are added to maintain smoothness and scratch resistance. It is 0.1 to 1.0 weight% with respect to the water-soluble paint composition.

In the case of the additives of the present invention, the surface tension of the paint is lowered to improve surface properties such as wettability with the base material, smoothness and scratch resistance of the coating film, but because it provides a cause of bubble generation, the range of the above-mentioned amount used in the manufacture of the paint is limited. Do not cross it.

In addition, the flow control agent used in the paint composition of the present invention has a high viscosity at a low shear rate, such as during the storage of the paint, viscosity at the intermediate shear rate, such as a paint supply line to facilitate rapid paint transfer, painting work In high shear rate conditions, such as the case, the viscosity is extremely low to give the best atomization behavior.When the paint adheres to the substrate, the shear rate returns to a very low condition, so the viscosity increases immediately to control the flow and flow of the paint. In the present invention, the fluidity modifier of the type HEUR (Hydrophobically Modified Ethylene oxide Urethane block Copolymer thickner) is used, the amount of which is added in 0.5 to 2.5% by weight based on the total water-soluble coating composition.

In addition, in the coating composition of the present invention, a water-soluble paint forms a coating film, which is exposed to the outside, resulting in loss of gloss caused by degradation and erosion of the coating film due to photooxidation, cracking, fading of pigment, chalking, UV absorbers and amine inhibitor UV stabilizers are used to prevent loss of adhesion and yellowing. Two kinds of UV stabilizers should be used in a solid ratio of 2: 1, and its amount should be used in an amount of 2 to 4% by weight based on the total water-soluble coating composition.

Therefore, in the present invention, when the coating by adding a curing agent, additives and co-solvent to the water dispersion resins prepared above, the hydroxyl group of the acrylic resin and urethane oligomer and the butylol or methylol of the amino resin at 130 ~ 150 ℃ The molecular structure of the resins was designed to complete the film formation by condensation reaction with groups and urethane reaction with residual isocyanate groups formed by dissociation of the blocking agent of the block isocyanate.

The present curing system will be described in more detail. When applied to a water-soluble one-component transparent top coat for automobiles using the water-dispersible resin and the hardening agent of the present invention, the water-dispersible resin and the hardening agent may be Air spray or bell coating the prepared one-component water-soluble transparent paint to 40 to 50 microns as a dry coating film, and maintained the setting time (5-10 minutes) at room temperature at 80 ℃ using an IR oven. Flash off is given for 5 minutes and heat cured at 130-150 ° C. for 20-30 minutes in a convection oven.

Therefore, the coating composition of the present invention was to optimize the physical properties of the coating film by adding a curing agent, additives and co-solvent to the water dispersion main resins prepared in the present invention.

In addition, when applying the coating material of the water-dispersible resin and the cured resin prepared in the present invention, by combining the solid content of the resin to be 80:20 ~ 50:50, it is possible to form a transparent coating film for automotive use, in particular the present invention As the curing agent used in the coating composition of the mixed isocyanate resin and amino resin is mixed and applied, the non-yellowing trimer type was applied as the block isocyanate resin, methylated melamine resin having butylated melamine and amino as the amino resin The mixed use of block isocyanate resin alone can increase the cost of the paint as well as increase the yellowing property of the coating film. The use of amino resin alone can save the coating material, the water resistance of the coating film, acid resistance and cold resistance chipping. ) Can weaken the sex. Therefore, the mixing ratio of the block isocyanate resin and the amino resin applied to the coating composition of the present invention does not exceed the range of 70:30 to 30:70, and contains 15 to 35% by weight of the total coating composition.

In addition, a coating agent is applied to the coating composition of the present invention for improving the appearance of the coating film.

In the coating composition of the present invention, the re-part of the solvent is composed of water, so that bubbles are generated at the time of coating production. Therefore, in the water-soluble coating composition of the present invention, propylene glycol or dipropylene glycol is added as a cosolvent, and the role of the cosolvent improves the wettability and smoothness of the paint, lowers the minimum film forming temperature, and makes the coating atomization ( It not only facilitates the phenomenon of paint atomizing from the nozzle of the coating machine, but also greatly contributes to the volatilization of the solvent, and in particular, controls the popping phenomenon during curing of the coating film. Therefore, the amount of the cosolvent used in the present invention contains 4 to 10% by weight based on the total water-soluble coating composition.

The following preparation example is described in '95 Korea Patent Co., Ltd. patent application (No. 95-69631), the embodiment is applied to the main resin prepared in the preparation example, the water-soluble one-component transparent topcoat of the present invention The manufacturing process, components, and efficacy and effects are described in more detail, but do not limit the scope of the present invention.

Production Examples 1 to 2 are methods for synthesizing urethane oligomers, Production Examples 3 to 4 are methods for synthesizing reactive polymers of urethane oligomers and isocyanates, Production Examples 5 to 6 are methods for synthesizing acrylic main resins, and Production Examples 7 to 8 Method for producing a water-dispersible resin, Example 1 relates to the production of paints having different composition ratios using the main resins prepared in the above production example, a curing agent, an additive, a coarse solvent, and the like.

Preparation Example 1

Synthesis of Urethane Oligomers (U1)

The monomer composition of the urethane oligomer is shown in Table I below.

TABLE I

Weight of substance

Butanol 400

Propylene Carbonate 400

Diethylene triamine 200

Total 1000

In the above reaction, butanol and propylene carbonate were introduced into a four-necked flask equipped with a thermometer and a dropping funnel to maintain the temperature at 40 ° C. Then diethylene triamine is added dropwise over 1 hour and maintained for 1 hour. The end of the reaction was verified by titration of unreacted amine. The final material was confirmed by an analyzer such as NMR, IR, GPC, the solid content is 60%, and has a glass transition temperature of about 40.

Preparation Example 2

Synthesis of Urethane Oligomers (U2)

The monomer composition of the urethane oligomer is shown in Table II below.

TABLE II

Weight of substance

Butanol 400

Propyrene Carbonate 400

Dipropylene triamine 200

Total 1000

In the above reaction, butanol and propylene carbonate were introduced into a four-necked flask equipped with a thermometer and a dropping funnel to maintain the temperature at 40 ° C. Dipropylene triamine is then added dropwise over 1 hour and held for 1 hour. The end of the reaction was verified by titration with unreacted amine. The final material was confirmed by an analyzer such as NMR, IR, GPC, the solid content is 60%, and has a glass transition temperature of about -35.

Preparation Example 3

Reaction polymer synthesis of urethane oligomer and isocyanate (1,2,3,4,5,6) monomer composition is shown in Table III.

TABLE III

Substance PU1 PU2 PU3 PU4 PU5 PU6

Urethane Oligomer 900 900 900 900 900 900

(U1)

HMDI 100

IPDI 100

TMXDI 100

HMDI trimer 100

IPDI trimer 100

TMXDI trimer 100

Total 1000 1000 1000 1000 1000 1000

HMDI: hexamethylene diisocyanate

IPDI: isophorone diisocyanate

TMXDI: tetramethyl xylene diisocyanate

diisocyanate)

HMDI trimer: trimer of hexamethylene diisocyanate

IPDI trimer: trimer of isophorone diisocyanate

TMXDI trimer: trimer of tetramethyl xyylene diisocyanate

The above reaction was carried out in a four-necked flask equipped with a thermometer and a dropping funnel, and the solution phase urethane oligomer was kept at 50 ° C. Then, each isocyanate is dripped over 1 hour, and it keeps for 1 hour, and after measuring the residual amount of isocyanate, reaction is maintained until there is no unreacted isocyanate. Final material was confirmed by an analyzer such as NMR, IR, GPC, etc., the solid content is 72%.

Preparation Example 4

Synthesis of the reactive polymer of the urethane oligomer and isocyanate (7,8,9,10,11,12) The monomer composition is shown in Table IV.

[Table IV] Unit: parts by weight

Substance PU7 PU8 PU9 PU10 PU11 PU12

Urethane Oligomer 900 900 900 900 900 900

(U2)

HMDI 100

IPDI 100

TMXDI 100

HMDI trimer 100

IPDI trimer 100

TMXDI trimer 100

Total 1000 1000 1000 1000 1000 1000

The above reaction was carried out in a four-necked flask equipped with a thermometer and a dropping funnel, and the solution phase urethane oligomer was kept at 50 ° C. Thereafter, each isocyanate is added dropwise over 1 hour and maintained for 1 hour, and then the remaining amount of isocyanate is measured to maintain the reaction until there is no unreacted isocyanate. The final material was confirmed by an analyzer such as NMR, IR, GPC, the solid content is 72%.

Preparation Example 5

Acrylic Resin Synthesis (A1)]

The monomer composition and the synthesis process of the acrylic resin are shown in Table V below.

TABLE V

Weight of substance

part I

Xylene 50

Buthanol 11

Part II

Acrylic acid 31

Butyl acrylate 89

2-EHA 30

HEMA 63

SM 30

TBPB 16

Total 320

2-EHA: ethylhexyl acrylate

EMA: hydroxyethyl methacrylate

SM: Styrene Monomer

TBPB: tribenzoylperoxybenzoate

In the above reaction, a mixture of xylene and butanol in a 5: 1 ratio is added to a four-necked flask equipped with a thermometer and a dropping funnel, and the temperature is maintained at 110 ° C. Thereafter, the mixture of the above monomers is slowly added dropwise over 3 hours. It is maintained for about 2 hours after the end of dropping. The final material was confirmed by an analyzer such as NMR, IR, GPC, and the like was removed by removing the solvent by depressurizing the above material and replaced with PM Acetate (methoxy propyl acetate). Solid content is 70%, has a glass transition temperature of about 10, acid number 25, number average molecular weight 7000, and polydispersity 3.5.

Preparation Example 6

Acrylic Resin Synthesis (A2)

As the acrylic resin, a commonly used monomer was used, and the composition and synthesis process of the monomer are shown in Table VI below.

Table VI

Weight of substance

part I

PM Acetate 88

Part II

Acrylic acid 31

Butyl acrylate 89

2-EHA 30

HEMA 63

SM 30

TBPB 16

Total 320

In the above reaction, put PM Acetate in a four-necked flask equipped with a thermometer and a dropping funnel and keep the temperature at 110 ° C. Thereafter, the mixture of the above monomers is slowly added dropwise over 3 hours. It is maintained for about 2 hours after the end of dropping. The final material was confirmed by an analyzer such as NMR, IR, GPC, etc., the solid content is 70%, has a glass transition temperature of about 9, the acid value 26, the number average molecular weight is 9000, and the polydispersity is 3.1.

Preparation Example 7

Water Dispersion Resin (UD1)

The water dispersion composition and process are shown in Table VII below.

[Table VII]

Weight of substance

Acrylic Resin Resin (A1) 500

Urethane Oligomers and Isocyanate Polymers (PU4) 100

DMEA 14

Amino resin * 100

Block Isocyanate Resin * 50

Distilled water 800

Total 1464

* Amino resin: butylated or methylated high imino type melamine resin Monsanto brand name BM-5901

* Block isocyanate resin: Brand name DP-9B / 1059 of block isocyanate Baksenten Co., Ltd. of a non-sulfurized trimer type.

The method first removes the solvent of the acrylic resin under reduced pressure. At this time, the temperature is 100 ° C. Then, the urethane oligomer and the isocyanate polymer are added to the mixture, followed by complete stirring. After stirring, the temperature was lowered to 80 ° C. and neutralized with DMEA (dimethyl ethanol amine). Maintain about 30 minutes after neutralization, lower the temperature to 70 ℃, and add melamine resin and blocked isocyanate. After maintaining for about 30 minutes and distilled water was slowly added dropwise for 1 hour to prepare an aqueous dispersion. The solids content of the above aqueous product is 40.0%.

Preparation Example 8

Water Dispersion Resin (UD2)

The composition and the process of the water dispersion resin are shown in Table VII below.

[Table VII]

Material weight ratio

Acrylic Resin Resin (A2) 500

Urethane Oligomers and Isocyanate Polymers (PU4) 100

DMEA 14

Amino resin * 100

Block Isocyanate Resin * 50

Distilled water 800

Total 1464

The amino resin and the block isocyanate resin are the same as in Preparation Example 8.

The method first removes the solvent of the acrylic resin under reduced pressure. At this time, the temperature is 100 ° C. Then, the urethane oligomer and the isocyanate polymer are added to the mixture, followed by complete stirring. After stirring, the temperature was lowered to 80 ° C. and neutralized with DMEA (dimethyl ethanol amine). Maintain about 30 minutes after neutralization, lower the temperature to 70 ℃, and add melamine resin and blocked isocyanate. After maintaining for about 30 minutes and distilled water was slowly added dropwise for 1 hour to prepare an aqueous dispersion. The solids content of the above aqueous product is 40.0%.

Example 1

The paint was prepared by the conventional method with the composition and the quantity shown in following Table V, and the physical properties are described in Table V below.

[Table VII]

1-component transparent top coat composition (applied with water dispersion resin UD1,2, solvent type resin A1, A2)

Paints 1 Paints 2 Paints 3 Paints 4

Water Dispersion Resin (UD1) 86

Water Dispersion Resin (UD2) 86

Acrylic main resin (A1) 35.5

Acrylic main resin (A2) 35.5

Urethane Oligomers and Isocyanate Polymers (PU4) 4.0 4.0

Propylene glycol (dipropylene glycol) 5.5 5.5 5.5 5.5

Dimethylethanol Amine 0.1 0.1 0.1 0.1

Made in MAR SLIP 0.1 0.1 0.15 0.15

Wetting Agent 0.4 0.4 0.3 0.3

Leveling agent 0.5 0.5 0.5 0.5

Antifoam 1.0 1.0 0.8 0.8

Fluidity regulator 2.0 2.0 2.5 2.5

UV absorbers 1.6 1.6 1.6 1.6

Amine Inhibitor UV Stabilizer 0.8 0.8 0.8 0.8

Amino Resin (1) 4.7 4.7

Amino resin (2) 3.6 3.6

Block Isocyanate Resin 7.5 7.5

Distilled Water 2.0 2.0 32.45 32.45

Total (% by weight) 100 100 100 100

Solids 36.9 36.9 42.23 42.23

pH 8.5 8.5 8.5 8.5

Viscosity (FORD CUP # 4, SEC) 35 35 35 35

[Table VII]

Property

Properties Paint 1 Paint 2 Paint 3 Paint 4 Pencil hardness HB and above HB and above HB and above HB and above Glossy (20/60。) 86/93 87/95 84/92 86/94 Sharpness (image sharpness, horizontal) 0.9 or more 0.9 or more 0.9 or more 0.9 or more Acid resistance 60 degrees Pass Pass Pass Pass 70 degrees refuse refuse refuse refuse Water resistance Pass Pass Pass Pass Over-backing (△ E) 3.3 3.1 3.3 3.1 Nice Crash Castle 85% 87% 85% 87% Chipping resistance 1-2mm below 10 below 10 below 10 below 10 More than 2mm One 0 One 0 Weather resistance Glossy retention rate 80% 85% 80% 855 (△ E) 1.0 0.5 1.0 0.5

Amino Resin (1): Cytec-Cymel-325

Amino Resin (2): Monsanto, BM-5901

Block isocyanate resin: Trixene DP 9B / 1059 from Baxenden

Product made in Mar Slip: BYK-Chemie company

Wetting agent: BYK-Chemie company name

Leveling agent: BYK-Chemie trade name Byketol-WS

Defoamer (Deformer): BYK-Chemie company brand name BYK-011

Rheology modifier: Lanco trade name PLIR-21

UV absorber: Ciba-Geigy

Amine-inhibiting UV stabilizer: Ciba-Geigy company Tinlivin-292

* Acid resistance: 10% sulfuric acid spot test (spot test, 60 ℃ x 30min)

* Scratch resistance: Car wash test (20。 Gloss retention rate)

* Over-backing: After curing the cured film at 160 ℃ for 30 minutes, measure yellowing degree (△ E) (measured with Spectrophotometer)

* Pencil hardness: measured by Mitsubishi Uni-Pencil

* Image Sharpness: Measure video sharpness with PGD meter

* Water resistance: Gloss change and adhesion measurement after 240 hours immersion in 40 ℃ water

* Cold resistance chipping: Measured with chipping tester after 3 hours at -40 ℃ (Honta stone, 50g)

* Weather resistance: 4000 hours measured every 400 hours with Xenon Weather-O-metes (Cycle CAM 180)

The coating composition according to the present invention can be applied as a small-type transparent top coating for automobiles, and as can be seen from Table VII above, it forms a high gloss coating film, and is excellent in acid, water, chipping, and scratch resistance. Do.

Claims (6)

40-75 wt% of water-dispersible resin composition containing urethane oligomer having four or more hydroxyl groups induced by reaction of alkylene carbonate and polyamine, 15-35 wt% of curing resin, 3.2-11.5 wt% of additive, and crude 4 A low-temperature baking type transparent top coat composition comprising -15 wt%. The low-temperature baking type transparent topcoat composition according to claim 1, wherein the solid content ratio of the water-dispersible resin composition and the curing resin is 80:20 to 50:50. The low-temperature baking type transparent topcoat composition according to claim 2, wherein the curing resin has a utilization ratio of a block isocyanate resin and an amino resin of 70:30 to 30:70. The low-temperature baking type transparent topcoat composition according to claim 3, wherein the mixing ratio of the butylated melamine resin and the methylated melamine resin having an amino group in the amino resin as the curing resin is 70:30 to 30:70. According to claim 1, wherein the additive is 0.5 to 3.0% by weight of the defoaming agent, 0.1 to 1.0% by weight of polysiloxane-based wetting agent, 0.1 to 1.0% by weight of polysiloxane-based smoothing agent, 0.5 to 2.5% by weight of the fluidity regulator, and ultraviolet absorber and amine inhibitor UV A low-temperature calcined transparent top coat composition comprising 2 to 4 wt% stabilizer. The low temperature sintered transparent top coat composition according to claim 1, wherein the co-solvent is used alone or in combination of propylene glycol or dipropylene glycol.