WO2023113256A1

WO2023113256A1 - Water-soluble polyisocyanate and water-soluble clear coat composition including same

Info

Publication number: WO2023113256A1
Application number: PCT/KR2022/018092
Authority: WO
Inventors: 정윤섭; 김창혁; 박종윤; 조수영; 박장호; 형우찬; 김맹기; 이현주; 강홍구; 최은성
Original assignee: 주식회사 케이씨씨
Priority date: 2021-12-13
Filing date: 2022-11-16
Publication date: 2023-06-22
Also published as: KR20230089476A

Abstract

The present invention relates to a water-soluble polyisocyanate and a water-soluble clear coat composition including same, the water-soluble polyisocyanate being obtained from a polyisocyanate compound, a silane-based monomer, and a sulfonic acid-based monomer and comprising, on the basis of the total weight of a composition for the preparation of the water-soluble polyisocyanate, 3-20 wt% of the silane-based monomer and 2-10 wt% of the sulfonic acid-based monomer.

Description

Water-soluble polyisocyanate and water-soluble clear coat composition containing the same

The present invention relates to a water-soluble polyisocyanate and a water-soluble clear coat composition containing the same, and more particularly, to a two-part water-soluble polyisocyanate and a two-part water-soluble clear coat composition containing the same.

[National research and development project supporting this invention]

[Assignment identification number]1415173343

[Task number]20010566

[Name of Department] Ministry of Trade, Industry and Energy

[Task management (professional) organization name] Korea Evaluation Institute of Industrial Technology

[Research project name] Material parts technology development (R&D)

[Research Project Name] Development of VOC-free water-based transparent coating varnish material and process technology for transportation equipment

[Contribution rate] 1/1

[Name of the organization performing the project] KCC Co., Ltd.

[Research period] 20210101 ~ 20211231

In general, the exterior plate of a vehicle body must be free from deterioration and rust of a coating film and must have durability capable of maintaining the gloss or color of the coating film. Therefore, in the painting process of a vehicle, after electrodeposition coating of a vehicle body that has undergone a pretreatment process, intermediate (primer) painting is performed to improve adhesion and smoothness, and base painting is applied to the intermediate painted vehicle body for aesthetics of the vehicle body. . After that, it is common to paint a clear coat to protect the color of the base coat, improve the appearance, and protect the base coat from the outside.

In the case of a clear coat, a material based on usefulness is usually used, and since this is a very non-environmental material, the need to replace it with a water-soluble material is increasing.

Korean Patent Registration No. 10-1310616 discloses a water-soluble top coating composition for automobiles applicable to multiple clear coats, but it relates to a water-soluble top coating composition for automobiles applicable as a base coat.

Korean Patent Registration No. 10-1881216 discloses a water-based paint composition, but it relates to an aqueous paint composition for a base coat of an automobile body that does not include an intermediate coating and a clear coat.

Therefore, there is a continuing demand for a water-soluble clear coat composition for converting an oil-based system conventionally applied to a clear coat into an eco-friendly water-soluble system for the purpose of preparing for environmental regulations and reducing VOC.

On the other hand, a coating film obtained by using a paint crosslinked with an isocyanate-based compound may exhibit excellent abrasion resistance, chemical resistance, and contamination resistance. In addition, a coating film using a non-yellowing polyisocyanate using aliphatic alicyclic diisocyanate as a raw material as an isocyanate component exhibits excellent weatherability, and demand for it is increasing.

Accordingly, there is a continuing demand for water-soluble polyisocyanates that can be used in water-soluble paints and do not impair paint properties, and in particular, a demand for technologies for improving exterior characteristics, weather resistance, and scratch resistance using water-soluble polyisocyanates is increasing.

[Prior art literature]

(Patent Document 1) Republic of Korea Patent Registration No. 10-1310616 (2013.09.13.)

(Patent Document 2) Republic of Korea Patent Registration No. 10-1881216 (2018.07.17.)

In one aspect, the present invention intends to provide a two-component water-soluble polyisocyanate having improved water dispersibility, which can be used for preparing a water-soluble clear coat.

Another aspect of the present invention is to provide a two-component water-soluble clear coat composition containing a water-soluble polyisocyanate.

In one aspect, the present invention is a water-soluble polyisocyanate obtained from a polyisocyanate compound, a silane-based monomer and a sulfonic acid-based monomer, based on the total weight of a composition for preparing water-soluble polyisocyanate, 3 to 20% by weight of a silane-based monomer and a sulfonic acid-based monomer It provides a water-soluble polyisocyanate containing 2 to 10% by weight.

The water-soluble polyisocyanate according to one aspect of the present invention has improved water dispersibility and can be used to prepare a two-component water-soluble clear coat that can be diluted with water.

The two-component water-soluble clear coat composition according to another aspect of the present invention can be used after being diluted with water and can form a coating film having excellent appearance properties, weather resistance and scratch resistance.

Hereinafter, the present invention will be described in detail.

1. Water-soluble polyisocyanates

The present invention provides water-soluble polyisocyanates.

The water-soluble polyisocyanate of the present invention is obtained from a polyisocyanate compound, a silane-based monomer and a sulfonic acid-based monomer.

The water-soluble polyisocyanate of the present invention may include 3 to 20% by weight of a silane-based monomer and 2 to 10% by weight of a sulfonic acid-based monomer based on the total weight of the composition for preparing the water-soluble polyisocyanate.

Hereinafter, the above configurations will be described in detail.

polyisocyanate compound

A polyisocyanate compound is a general term for compounds containing one or more isocyanate groups. The polyisocyanate compound may be, for example, a polyisocyanate compound such as an aliphatic polyisocyanate compound, an alicyclic polyisocyanate compound, or an aromatic polyisocyanate compound, but is not limited thereto. Preferably, a polyisocyanate trimer may be used.

Examples of the aliphatic polyisocyanate compound include trimethylene diisocyanate, 1,2-propylene diisocyanate, and butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate), 1,5-pentamethylene diisocyanate (PDI), 1,6-hexamethylene diisocyanate (HMDI), 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl capate, and the like, but are not limited thereto.

Examples of the alicyclic polyisocyanate compound include 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, and cyclohexane diisocyanate (1,3- or 1,4-cyclohexane diisocyanate). , 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), methylenebis(cyclohexyl isocyanate) (4,4'-, 2,4'- or 2, 2′-methylenebis(cyclohexyl isocyanate), their trans, trans-isomers, cis, cis-isomers, or mixtures thereof) (H ₁₂ MDI), methylcyclohexane diisocyanate (methyl-2,4-cyclohexyl Cein diisocyanate, methyl-2,6-cyclohexane diisocyanate), norborneine diisocyanate (NBDI), bis(isocyanatomethyl)cyclohexane (1,3- or 1,4-bis(iso cyanatomethyl) cyclohexane or mixtures thereof) (H ₆ XDI) and the like, but are not limited thereto.

As the aromatic polyisocyanate compound, for example, tolylene diisocyanate (2,4- or 2,6-tolylene diisocyanate or a mixture thereof) (TDI), phenylene diisocyanate (m-, p-phenylene diisocyanate or mixtures thereof), 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate (NDI), diphenylmethane diisocyanate (4,4'-, 2,4'- or 2,2'-diisocyanate phenylmethane diisocyanate or mixtures thereof) (MDI), 4,4'-toluidine diisocyanate (TODI), 4,4'-diphenylether diisocyanate, xylylene diisocyanate (1,3- or 1,4 - xylylene diisocyanate or mixture thereof) (XDI), tetramethylxylylene diisocyanate (1,3- or 1,4-tetramethylxylylene diisocyanate or mixture thereof) (TMXDI), ω,ω'-diisocyanate -1,4-diethylbenzene and the like, but is not limited thereto.

As the polyisocyanate compound, a single compound may be used or two or more types may be used in combination, but is not limited thereto.

In one embodiment, the polyisocyanate compound may be preferred because aliphatic polyisocyanate compounds and alicyclic polyisocyanate compounds are excellent in weather resistance.

Among the aliphatic polyisocyanate compounds, an aliphatic polyisocyanate compound derived from an aliphatic diisocyanate is preferred. More specifically, the aliphatic diisocyanate is 1,6-hexamethylene diisocyanate trimer, or 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate in terms of weatherability and industrial availability. (isophorone diisocyanate, IPDI) trimers may be preferred, but are not limited thereto.

The isocyanate content of the polyisocyanate compound is preferably 10 to 30%, for example 15 to 25%.

Water-soluble clear exhibiting excellent physical properties such as appearance, water dispersibility, and scratch resistance by using a water-soluble polyisocyanate having an isocyanate group content within the above range and formed by reacting such an isocyanate group with a silane-based monomer and a sulfonic acid-based monomer. A coat composition may be provided.

The polyisocyanate compound may be included in an amount of 50 to 80% by weight, or 54 to 75% by weight based on the total weight of the composition for preparing the water-soluble polyisocyanate. When a clear coat composition containing a water-soluble polyisocyanate having a content of the polyisocyanate compound within the above range is used, a coating film having excellent physical properties such as abrasion resistance, chemical resistance, stain resistance, and scratch resistance can be formed. In addition, it is possible to provide a water-soluble clear coat composition exhibiting excellent water dispersibility through a reaction with a sulfonic acid-based monomer.

monomer

Here, the water-soluble polyisocyanate may be obtained from 50 to 80 parts by weight of a polyisocyanate compound and 5 to 30 parts by weight of a monomer, or 54 to 75 parts by weight of a polyisocyanate compound and 9 to 26 parts by weight of a monomer, but is not limited thereto. .

The content of isocyanate groups in the water-soluble polyisocyanate may be 10 to 17 NCO%, or 10 to 15 NCO%.

When the content of the polyisocyanate compound and the monomer is within the above range, a desired two-component water-soluble clear coat composition can be provided. When the content is less than the above range, the degree of improvement in water dispersibility is insignificant, and when the content exceeds the above range, the physical properties of the formed coating film are deteriorated. problems may appear.

The monomer may include a silane-based monomer and a sulfonic acid-based monomer. In this way, water-soluble polyisocyanate can be obtained by reacting the two types of monomers with the polyisocyanate compound, respectively. By using these two types of monomers in combination, the water dispersibility of the water-soluble clear coat composition containing water-soluble polyisocyanate can be improved, and the physical properties of a coating film formed using the same can be improved. Hereinafter, the above two types of monomers will be described in detail.

<Silane-based monomer>

The silane-based monomer serves to increase the curing density of the water-soluble polyisocyanate and improve scratch resistance of a coating film formed from a clear coat composition containing the same.

A silane-based monomer is a compound having a -Si(OR) _n group capable of reacting with isocyanate. The silane-based monomer may combine with the polyisocyanate compound to form a silane-modified isocyanate group. The -Si(OR) _n group combined with isocyanate undergoes a hydrolysis reaction and self-condensation reaction to form a -Si-O-Si- structure or an organic chemical bond of a -Si-O- structure by heat.

The silane-based monomer may have a hydroxyl group, an amino group, or a combination thereof, but is not limited thereto.

The silane-based monomer is gamma-aminopropyltrimethoxysilane (Silquest A-1100), bis (trimethoxysilylpropyl) amine (Silquest A-1170), bis (triethoxy Silylpropyl)amine (Bis(triethoxysilylpropyl)amine, Siquest Y-11699), Organoalkoxysilane (Silquest Y-96699), 3-Glycidoxypropyl trimethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane (N-( 2-aminoethyl) 3-aminopropyltrimethoxysilane), bis-gamma-trimethoxysilylpropylamine, bis-gamma-triethoxysilylpropylamine, and at least one selected from the group consisting of aminopropyltriethoxysilane. there is.

The silane-based monomer may be included in an amount of 3 to 20% by weight or 6 to 15% by weight based on the total weight of the composition for preparing the water-soluble polyisocyanate. When the silane-based monomer is included within the above content range, an appropriate siloxane bond is formed to improve adhesion and durability of the coating film. If the content of the silane-based monomer is less than the above range, the number of siloxane bonds is small and the crosslinking density is lowered, resulting in a decrease in adhesion, gloss and durability of the coating film. Due to the resulting hydrolysis, the storage property of the paint may be deteriorated, and thus the appearance of the paint film and scratch resistance may be deteriorated.

The sulfonic acid-based monomer serves to control the hydrophilicity of water-soluble polyisocyanate.

Sulfonic acid-based monomers can react with isocyanate groups.

The sulfonic acid-based monomer may include, for example, at least one selected from the group consisting of aminoalkyl sulfonic acids and hydroxyl aminoalkyl sulfonic acids having a sulfonic acid group.

Aminoalkyl sulfonic acids or hydroxyl aminoalkyl sulfonic acids include cyclohexyl amino methane sulfonic acid, cyclohexyl amino ethane sulfonic acid, cyclohexyl amino propane sulfonic acid (CAPS), cyclohexyl amino butane sulfonic acid, ethyl amino propane sulfonic acid, At least one selected from the group consisting of isobutyl amino propane sulfonic acid, isopropyl amino propane sulfonic acid, hydroxyl ethyl piperazine methane sulfonic acid, hydroxy ethyl piperazine ethane sulfonic acid, hydroxyl ethyl piperazine propane sulfonic acid, and the like can include

For aminoalkyl sulfonic acids and hydroxyl aminoalkyl sulfonic acids, tertiary amines can be employed for reaction with isocyanate groups.

As the tertiary amine, it may be applied as long as it does not inhibit the reaction with the isocyanate group, and for example, triethylamine, dimethyl cyclohexyl amine, and the like may be used.

The sulfonic acid-based monomer may be included in an amount of 2 to 10% by weight or 3 to 8% by weight based on the total weight of the composition for preparing the water-soluble polyisocyanate. When the sulfonic acid-based monomer is included within the above content range, there is an effect of improving storage stability and mechanical properties by generating an appropriate number of hydrophilic groups. When the content of the sulfonic acid-based monomer is less than the above range, the number of hydrophilic groups is small, resulting in a decrease in compatibility of the resin composition. Gloss and scratch resistance may be reduced.

For example, the weight ratio of these two monomers to the silane-based monomer and the sulfonic acid-based monomer may be 1:0.1 to 3 or 1:0.2 to 1. These two monomers are used in the above weight ratio to maintain the resin composition and appropriate crosslinking density due to increased reactivity to provide a clear coat composition with excellent physical properties such as appearance, gloss, adhesion, impact resistance, and scratch resistance as well as water dispersibility. can do.

Formation of water-soluble polyisocyanate

The water-soluble polyisocyanate of the present invention may be prepared, for example, by mixing a polyisocyanate compound and a sulfonic acid-based monomer in a solvent for a first reaction, and then adding a silane-based monomer for a second reaction. The primary reaction between the polyisocyanate compound and the sulfonic acid monomer may be carried out at 30 to 50 °C, for example, 40 °C, and the secondary reaction may be carried out at 85 to 95 °C, for example, 90 °C.

As the solvent, commonly used solvents can be used without limitation, but methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, ethyl propyl ketone, methyl isobutyl ketone, methyl aryl ketone, which do not affect the polyisocyanate reaction and water-soluble paint, Ketone solvents such as diisobutyl ketone, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, methyl cellosolve acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, propylene glycol Acetate-based solvents such as methyl ether acetate (PMA) or alcohol-based solvents such as n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, butanediol, and butyl cellosolve, or mixed solvents thereof may be used. .

The water-soluble polyisocyanate according to the present invention may contain an organic chemical bond of a -Si-O-Si- structure or a -Si-O- structure by a silane-based monomer, and an ionic (SO ₃ ^- ) group by a sulfonic acid-based monomer. may contain. The water-soluble polyisocyanate of the present invention has technical characteristics in improving water dispersibility and physical properties of a coating film formed from the clear coat composition used by the above two monomers and their content ratio.

In addition, the water-soluble polyisocyanate may have a weight average molecular weight (Mw) of 500 to 5,000, for example, 800 to 2,000.

When the weight average molecular weight of the water-soluble polyisocyanate is within the above range, an appropriate reaction rate is maintained to improve reactivity with the resin, thereby increasing the crosslinking density of the coating film, thereby improving mechanical properties, appearance and chemical resistance.

When the weight average molecular weight of the water-soluble polyisocyanate is less than the above range, the reactivity is lowered and the compatibility and appearance of the resin composition is lowered. Appearance and scratch resistance are deteriorated.

In forming the water-soluble polyisocyanate, the water-soluble polyisocyanate can be obtained in a mixed state with the unblocked polyisocyanate compound and/or the two monomers remaining after being used for isocyanate blocking. At this time, the obtained mixture may have a solid content of 70 to 90% by weight, or 75 to 85% by weight in the composition. In one example, a mixture with 80% solids was prepared.

As described above, the water-soluble polyisocyanate may have an isocyanate group content of 10 to 17 NCO%, or 10 to 15 NCO%.

The water-soluble polyisocyanate may have an Si(OR) ₃ content in the system of 2 to 14%, or 3 to 13%. Here, R is an alkyl group having 1 to 2 carbon atoms.

Meanwhile, the Si(OR) ₃ content can be obtained using the formula below.

Si(OR) ₃ % = silane-based monomer equivalent × Si(OR) ₃ molecular weight × F / total content × 100

where F = the number of Si(OR) ₃ in the polymer

The water-soluble polyisocyanate may have an SO ₃ ⁻ content in the system of 0.6 to 3.5%, or 1.0 to 3.0%.

Meanwhile, the SO ₃ ^- content can be obtained using the formula below.

SO ₃ ^- % = sulfonic acid monomer equivalent × SO ₃ ^- molecular weight × F / total content × 100

where F = SO ₃ ^- number in the polymer

When the NCO%, solid content, Si(OR) ₃ content, and SO ₃ ⁻ content of the water-soluble polyisocyanate are within the above ranges, it may be preferable in terms of crosslinking of the resin portion and the water-soluble polyisocyanate.

When the NCO% content of the water-soluble polyisocyanate is within the above range, the reactivity with the resin is improved and the crosslinking density of the coating film is increased, thereby improving mechanical properties, appearance and weather resistance.

NCO% of the water-soluble polyisocyanateWhen the content is less than the above range, the reactivity with the resin and crosslinking density are lowered, and thus the durability and chemical resistance of the prepared coating film is lowered. It deteriorates, resulting in lowered appearance, gloss and scratch resistance.

When the Si(OR) ₃ content of the water-soluble polyisocyanate is within the above range, an appropriate siloxane bond is formed, resulting in excellent storage stability and improved reactivity with the resin, thereby increasing the crosslinking density of the coating film to improve mechanical properties, appearance and weather resistance. has an effect.

When the Si(OR) ₃ content of the water-soluble polyisocyanate is less than the above range, the number of siloxane bonds is small and the crosslinking density of the coating film decreases, resulting in a decrease in weather resistance. Due to hydrolysis, the paint storage property is lowered, and thus the appearance, gloss and scratch resistance are lowered.

When the SO ₃ ^- content of the water-soluble polyisocyanate is within the above range, an appropriate number of hydrophilic groups is generated, so the storage stability is excellent and the reactivity with the resin is improved to increase the crosslinking density of the coating film, thereby improving mechanical properties, appearance and weather resistance. there is

When the SO ₃ ^- content of the water-soluble polyisocyanate is less than the above range, the number of hydrophilic groups is small and the reactivity is lowered, and the compatibility of the resin composition is lowered. deterioration, resulting in deterioration of appearance, gloss and scratch resistance.

The water-soluble polyisocyanate according to the present invention can be used as a two-component curing agent in paint compositions, pressure-sensitive adhesive compositions, adhesive compositions, casting agent compositions, and the like.

2. Water-soluble clear coat composition

The present invention can provide a two-component water-soluble clear coat composition comprising the water-soluble polyisocyanate according to the present invention.

The water-soluble clear coat composition according to the present invention may contain a water-soluble resin moiety together with the water-soluble polyisocyanate of the present invention. Specifically, the water-soluble clear coat composition according to the present invention may include 15 to 25 parts by weight of water-soluble polyisocyanate and 40 to 130 parts by weight of water-soluble resin.

The water-soluble resin part may include an acrylic dispersion resin, a water-soluble polyester resin, a urethane dispersion resin, an acrylic emulsion resin, and a melamine resin. Specifically, the water-soluble resin part includes 20 to 50 parts by weight of acrylic dispersion resin, 1 to 15 parts by weight of water-soluble polyester resin, 1 to 15 parts by weight of urethane dispersion resin, 10 to 30 parts by weight of acrylic emulsion resin, and 5 to 15 parts by weight of melamine resin. It may contain parts by weight.

The acrylic dispersion resin serves to improve durability, appearance, and gloss of a coating film formed of a water-soluble clear coat composition.

The acrylic dispersion resin has a solid content of 40 to 50% by weight based on the total weight of the resin, a weight average molecular weight of 2,500 to 3,500 g / mol, a hydroxyl value of 100 to 150 mgKOH / g, and an acid value of 10 to 20 mgKOH / g, and may have a glass transition temperature of 25 to 35 °C.

The water-soluble polyester resin serves to improve the crosslinking density of the water-soluble clear coat composition.

The water-soluble polyester resin has a solid content of 70 to 80% by weight, a number average molecular weight of 900 to 1,100 g/mol, a hydroxyl value of 100 to 150 mgKOH/g, and an acid value of 15 to 30 mgKOH based on the total weight of the resin. /g, and the viscosity at 25° C. may be V to W Gardner viscosity.

The urethane dispersion resin serves to impart elasticity to a coating film formed of a water-soluble clear coat composition and to improve gloss, smoothness, and scratch resistance.

The urethane dispersion resin may have a solid content of 30 to 40% by weight based on the total weight of the resin, a weight average molecular weight of 20,000 to 30,000 g/mol, and a glass transition temperature of -20 to -10 °C.

The acrylic emulsion resin serves to adjust the rheology of the water-soluble clear coat composition.

The acrylic emulsion resin has a solid content of 35 to 45% by weight based on the total weight of the resin, a weight average molecular weight of 10,000 to 30,000 g / mol, a hydroxyl value of 10 to 100 mgKOH / g, and an acid value of 5 to 30 mgKOH / g, a glass transition temperature of -10 to 40 °C, and a viscosity at 25 °C of 100 to 1,000 cps.

The melamine resin serves to control the degree of curing and improve the hardness of the water-soluble clear coat composition. In one example, an alkylated melamine resin (Luwipal072, BASF) was used as the melamine resin.

The water-soluble polyisocyanate may be included in an amount of, for example, 15 to 25% by weight based on the total weight of the water-soluble clear coat composition. In one example, a water-soluble clear coat composition forming a coating film with excellent physical properties was prepared by mixing water-soluble polyisocyanate at 18% by weight based on the total weight of the water-soluble clear coat composition.

By including the water-soluble polyisocyanate according to the present invention, the water-soluble clear coat composition according to the present invention has improved water dispersibility and can be diluted with water. In addition, storage stability and weather resistance can be improved, and a coating film formed using the same can exhibit excellent physical properties such as appearance, gloss, adhesion, impact resistance, hardness, and scratch resistance.

The water-soluble clear coat composition according to the present invention may further include conventional components included in the water-based paint composition within a range that does not impair the object of the present invention together with the water-soluble polyisocyanate according to the present invention.

The water-soluble clear coat composition according to the present invention is an additive, for example, a rheology modifier (e.g., RM12W, DOW) added to adjust the rheological behavior of the composition, a light stabilizer for suppressing ultraviolet ray absorption and radical chain reaction by ultraviolet light (e.g. Tinuvin 1130 / Tinuvin 123 = 2/1), an acid catalyst to accelerate the reaction and control the curing rate (e.g. dodecylbenzenesulfonic acid type acid catalyst, NACURE 5225, King Industries), an antifoaming agent to inhibit blistering (eg, BYKETOL AQ, BYK), a wetting agent to improve wettability (eg, BYK-348, BYK), and the like.

On the other hand, the water-soluble clear coat composition according to the present invention may contain an organic solvent within a range that does not deteriorate the physical properties of the paint, such as butyl carbitol and dipropylene glycol n-butyl ether. ether), butyl cellosolve, and the like.

In addition, the water-soluble clear coat composition according to the present invention may include deionized water (DIW) as an aqueous solvent.

Hereinafter, the present invention will be described in more detail through examples.

However, these examples are only for helping the understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

With the compositions shown in Tables 1 and 2 below, water-soluble polyisocyanates were prepared in the following manner.

Example 1

In the amount shown in Table 1, the HMDI trimer was put into a four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen inlet pipe, and the temperature was raised to 40°C. Here, a sulfonic acid-based monomer is added, and the temperature is slowly raised and maintained to 80° C., and maintained until the primary NCO% is 19 to 19.5%. When the primary NCO% was 19 to 19.5%, a silane-based monomer (Silquest A-1170) was added and maintained. When the secondary NCO% reached 16.2 to 16.6%, a solvent propylene glycol methyl ether acetate (PMA) was added to terminate the reaction and cooled.

As a result of the reaction, a water-soluble polyisocyanate having a solid content (NV) of 80% by weight, an NCO content in the system of 13.98%, a Si(OR) ₃ content in the system of 5%, and a SO ₃ ^- content in the system of 1.31% was prepared.

NCO% was measured in the following way.

Weigh the sample containing isocyanate groups into a beaker (250 mL). Next, pipette 25 mL of 0.1N di-n-butylamine solution. Add 25 mL of 1,4-Dioxane (10 mL of reagent grade acetone if the polymer does not dissolve) and stopper the flask. Then mechanically stirring is continued for 15 minutes to dissolve the prepolymer. After dropping 4 to 6 drops of bromophenol blue indicator solution, rinse the beaker wall with 50 mL of isopropyl alcohol. Titrate with 0.1N hydrochloric acid until the end point is yellow. Put all the above reagents under the condition that no sample is added and perform the blank test.

The isocyanate group content is calculated as follows.

Solution: NCO content (%) = {(B-V)×N×0.4202} / W(g)}

From here,

B: The number of mL of hydrochloric acid consumed in the blank test

V: the number of mL of hydrochloric acid consumed for sample titration

0.4202: Milliequivalent weight of isocyanate group

W: weight of sample

Examples 2 to 13

Examples 2 to 13 were performed in the same manner as in Example 1 with the ingredients and contents shown in Table 1.

Comparative Examples 1 to 3

Comparative Examples 1 to 3 were performed in the same manner as in Example 1 with the components and contents shown in Table 2.

The physical properties of the water-soluble polyisocyanates prepared according to Examples and Comparative Examples are shown in Table 3 below.

A clear coat composition was prepared by mixing each of the water-soluble polyisocyanates of Examples 1 to 13 and Comparative Examples 1 to 3, a water-soluble resin part, an additive, and a solvent.

The contents of the water-soluble resin part, additives, solvents, and water-soluble polyisocyanates are shown in Table 4 below.

Table 5 below shows preparation examples and comparative preparation examples of clear coat compositions by adding the same main material and adding the water-soluble polyisocyanates of Examples 1 to 13 and Comparative Examples 1 to 3 as the curing agent.

The mixing ratio of the main agent and the curing agent was mixed based on R-NCO = 1.33.

A primer coating was applied to the electrodeposited steel sheet specimen and cured at 140° C. for 20 minutes to form a primer coating film having a thickness of 30 to 50 μm. Thereafter, a base coat was applied on the primer coating by bell spraying, and hot air was blown at 80° C. for 3 minutes to evaporate water remaining in the coating to form a base coating having a thickness of 15 μm. Thereafter, the clear coat composition prepared in Preparation Example and Comparative Preparation Example was coated on the base coating film and cured at 140 ° C. for 20 minutes to form a clear coating film having a thickness of 40 μm to prepare a final coating film.

The appearance characteristics and physical properties of the final coating film were measured in the following manner, and the results are shown in Table 6.

(1) Appearance

Gloss (LU), sharpness (SH), and orange peel (OP) were measured using Wave Scan DOI (BYK Gardner), an automotive exterior measuring instrument, for the final coating film manufactured, and comprehensive exterior evaluation values were used using the measured physical properties. (CF) was calculated by Equation 1 below.

[Equation 1]

CF = LU × 0.15 + SH × 0.35 + OP × 0.5

CF was measured and calculated horizontally and vertically. Horizontal/vertical value of CF. If CF is 79/74 or more, excellent (◎), 75/70 or more and less than 79/74 is good (○), 72/67 or more and less than 75/70 is average (△), 72/ If it was less than 67, it was evaluated as defective (x).

(2) Scratch resistance

As a method of measuring the resistance to scratches of the finished coating film using an automobile scratch resistance measuring instrument (AMTEC-KISTER), the gloss retention rate (%) was calculated by measuring the 20-degree gloss of the surface of the coating film before and after the test, and then evaluated. . According to the measurement result, if the gloss retention rate (%) is 70% or more, it is excellent (◎), if it is 60% or more and less than 70%, it is good (○), if it is 50% or more and less than 60%, it is normal (△), if it is less than 50%, it is bad ( ×).

(3) gloss

In order to measure the gloss (GLOSS, %) reflected from the coating film, the 20 ^o gloss of the final coating film was measured by applying a gloss machine (BYK Gardner). According to the measurement results, if the gloss was 91% or more, it was evaluated as excellent (◎), 89% or more and less than 91% as good (○), 87% or more and less than 89% as normal (△), and less than 87% as poor (×). .

(4) Chipping resistance

After the final coating film was left at -20 ° C for 3 hours, a 50 g chipping stone (diameter 4 mm) was hit at an angle of 45 ^° under a pressure of 5 bar. Thereafter, foreign substances such as peeled off coating film remaining in the final coating film were removed. Regarding the damaged part of the final coating film, if there are 10 or less damages of 1 mm or less, excellent (◎), if there are 10 or less damages of more than 1 mm and less than 2 mm, good (○), and damages of 2 mm or more and less than 3 mm 10 or less were evaluated as normal (Δ), and damages of 2 mm or more and less than 3 mm were evaluated as defective (×) if more than 10 damages.

(5) hardness

The hardness of the clear coating film was measured by the pencil hardness method. Specifically, the maximum hardness without damaging the clear coating film was measured using each of the pencils 2B, B, HB, F, H, and 2H.

As a result of the measurement, it was evaluated as excellent (◎) if it was higher than HB, good (○) if it was B, and poor (×) if it was less than B.

(6) Impact resistance

The impact resistance of the final coating film was evaluated according to ASTM D2794. A DuPont impact tester was used, and the appearance of the coating film was observed when a 500g weight was dropped on the specimen while changing the drop height of the weight from 30cm to 50cm.

As a result of observation, when cracks or peeling of the coating did not occur at a drop height of 50 cm or more, excellent (◎), when cracks or peeling occurred at a height of 30 cm or more and less than 50 cm, good (○), 20 cm If the crack or peeling phenomenon of the coating film occurred at less than 30 cm, it was evaluated as normal (Δ), and when the crack or peeling phenomenon of the coating film occurred at less than 20 cm, it was evaluated as defective (×).

(7) water resistance

The final coating film was immersed in a constant temperature water bath at 40° C. for 240 hours, left at room temperature for 1 hour, and then adhesion was evaluated by a checkerboard method, and discoloration was visually confirmed.

Specifically, the check mark method is a method of measuring adhesion by making 100 squares of 2 mm in width and 2 mm in length with a knife on the surface of the clear coating film and then using tape to remove the squares. % or more and less than 100% were evaluated as good (○), and less than 70% as poor (×).

As a result of the measurement, when the adhesion is good and there is no discoloration, it is evaluated as excellent (◎), when the adhesion is good but recovered after discoloration, it is evaluated as normal (Δ), and when the adhesion is poor or discolored, it is evaluated as poor (×).

(8) Solvent resistance

After placing a cotton cloth sufficiently soaked in xylene solvent on the surface of the final coating film, scraping it four times with a fingernail at a force of 2 kgf every 1 minute was measured for the time at which the base coating surface appeared.

The measurement result was evaluated as excellent (◎) if it was 10 minutes or more, good (○) if it was 7 minutes or more and less than 10 minutes, average (Δ) if it was 5 minutes or more and less than 7 minutes, and poor (×) if it was 5 minutes or less.

(9) Weatherability

The final coating film was tested for gloss retention (20 ^ㅇ gloss), adhesion, and color difference (X-Rite MA98) before and after 1,000 hours of exposure to WOM, an accelerated weather resistance tester.

Specifically, the check mark method of item (7) was used for adhesion. If the remaining squares are 100%, the gloss retention is 95% or more, and the color difference value (ΔE) is 1.0 or less, it is excellent (◎), and the remaining squares are 100% and glossy. If the retention rate is 90% or more and less than 95% and the color difference value (ΔE) is 1.0 or less, it is good (○), if the remaining square is less than 90%, the gloss retention rate is less than 90%, and the color difference value (ΔE) is more than 1.0, it is bad ( ×).

As can be seen in Table 6, the silane-based monomer is effective in improving the scratch resistance of the paint, and the sulfonic acid-based monomer is effective in improving the appearance.

In the above, the present invention has been described in detail only for the described embodiments, but it is clear to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention, and these changes and modifications are attached. It is natural that it belongs to the scope of the patent claims.

Hereinafter, various embodiments of the present invention will be described.

(1) A water-soluble polyisocyanate obtained from a polyisocyanate compound, a silane-based monomer, and a sulfonic acid-based monomer, 3 to 20% by weight of a silane-based monomer and 2 to 10% by weight of a sulfonic acid-based monomer, based on the total weight of a composition for preparing water-soluble polyisocyanate %, water-soluble polyisocyanate.

(2) A water-soluble polyisocyanate in which the content of isocyanate groups in the water-soluble polyisocyanate is 10 to 17 NCO%.

(3) Silane-based monomers include gamma-aminopropyltrimethoxysilane, bis(trimethoxysilylpropyl)amine, organoalkoxysilane, 3-glycy Doxypropyl trimethoxysilane (3-Glycidoxypropyl trimethoxysilane), N- (2-aminoethyl) 3-aminopropyltrimethoxysilane (N- (2-aminoethyl) 3-aminopropyltrimethoxysilane), bis-gamma-trimethoxysilyl A water-soluble polyisocyanate comprising at least one selected from the group consisting of propylamine, bis-gamma-triethoxysilylpropylamine, and aminopropyltriethoxysilane.

(4) Sulfonic acid-based monomers include cyclohexylaminomethanesulfonic acid, cyclohexylaminoethanesulfonic acid, cyclohexylaminopropanesulfonic acid (CAPS), cyclohexylaminobutanesulfonic acid, ethylaminopropanesulfonic acid, isobutylaminopropanesulfonic acid , isopropyl amino propane sulfonic acid, hydroxyl ethyl piperazine methane sulfonic acid, hydroxyl ethyl piperazine ethane sulfonic acid, and hydroxy ethyl piperazine propane sulfonic acid, a water-soluble polyisocyanate comprising at least one selected from the group consisting of .

(5) Based on the total weight of water-soluble polyisocyanate, the solids content (NV) is 70 to 90% by weight, the Si(OR) ₃ content in the system is 2 to 14%, and the SO ₃ ^- content in the system is 0.6 to 3.5%, Water-soluble polyisocyanates.

(6) A water-soluble clear coat composition comprising the water-soluble polyisocyanate according to any one of items (1) to (5) and a water-soluble resin part, wherein the water-soluble resin part is an acrylic dispersion resin, a water-soluble polyester resin, or a urethane dispersion resin. A water-soluble clear coat composition comprising a resin, an acrylic emulsion resin, and a melamine resin.

(7) A water-soluble clear coat composition comprising 15 to 25 parts by weight of a water-soluble polyisocyanate and 40 to 130 parts by weight of a water-soluble resin part.

(8) The water-soluble resin part includes 20 to 50 parts by weight of acrylic dispersion resin, 1 to 15 parts by weight of water-soluble polyester resin, 1 to 15 parts by weight of urethane dispersion resin, 10 to 30 parts by weight of acrylic emulsion resin, and 5 to 5 parts by weight of melamine resin A water-soluble clear coat composition comprising 15 parts by weight.

Claims

As a water-soluble polyisocyanate obtained from a polyisocyanate compound, a silane-based monomer and a sulfonic acid-based monomer,

A water-soluble polyisocyanate comprising 3 to 20% by weight of a silane-based monomer and 2 to 10% by weight of a sulfonic acid-based monomer based on the total weight of a composition for preparing water-soluble polyisocyanate.
The method of claim 1,

A water-soluble polyisocyanate having an isocyanate group content of 10 to 17 NCO% in the water-soluble polyisocyanate.
The method of claim 1,

Silane-based monomers include gamma-aminopropyltrimethoxysilane, bis(trimethoxysilylpropyl)amine, organoalkoxysilane, 3-glycidoxypropyl tri Methoxysilane (3-Glycidoxypropyl trimethoxysilane), N- (2-aminoethyl) 3-aminopropyltrimethoxysilane (N- (2-aminoethyl) 3-aminopropyltrimethoxysilane), bis-gamma-trimethoxysilylpropylamine, A water-soluble polyisocyanate comprising at least one selected from the group consisting of bis-gamma-triethoxysilylpropylamine and aminopropyltriethoxysilane.
The method of claim 1,

Sulfonic acid-based monomers include cyclohexyl amino methane sulfonic acid, cyclohexyl amino ethane sulfonic acid, cyclohexyl amino propane sulfonic acid (CAPS), cyclohexyl amino butane sulfonic acid, ethyl amino propane sulfonic acid, isobutyl amino propane sulfonic acid, isopropyl A water-soluble polyisocyanate comprising at least one selected from the group consisting of amino propane sulfonic acid, hydroxyl ethyl piperazine methane sulfonic acid, hydroxyl ethyl piperazine ethane sulfonic acid, and hydroxyl ethyl piperazine propane sulfonic acid.
The method of claim 1,

A water-soluble polyisocyanate having a solids content (NV) of 70 to 90% by weight, an Si(OR) 3 content in the system of 2 to 14%, and an SO 3 - content in the system of 0.6 to 3.5% based on the total weight of the water-soluble polyisocyanate. .
A water-soluble clear coat composition comprising the water-soluble polyisocyanate according to any one of claims 1 to 5 and a water-soluble resin moiety,

The water-soluble resin part includes an acrylic dispersion resin, a water-soluble polyester resin, a urethane dispersion resin, an acrylic emulsion resin, and a melamine resin.

A water-soluble clear coat composition.
The method of claim 6,

A water-soluble clear coat composition comprising 15 to 25 parts by weight of a water-soluble polyisocyanate and 40 to 130 parts by weight of a water-soluble resin part.
The method of claim 6,

The water-soluble resin part includes 20 to 50 parts by weight of acrylic dispersion resin, 1 to 15 parts by weight of water-soluble polyester resin, 1 to 15 parts by weight of urethane dispersion resin, 10 to 30 parts by weight of acrylic emulsion resin, and 5 to 15 parts by weight of melamine resin. A water-soluble clear coat composition comprising: