KR20200015250A - Blocked polyisocyanate and aqueous paint composition comprising thereof - Google Patents

Abstract

The present invention relates to blocked polyisocyanates and an aqueous coating composition. Block polyisocyanates of the present invention are obtained from a polyisocyanate compound and three types of blocking agents, wherein the three types of blocking agents comprise a methylene-based blocking agent, a polyalkylene polyol blocking agent, and a pyrazole-based blocking agent. Block polyisocyanates and the aqueous coating composition comprising the same according to the present invention may have improved water dispersibility.

Description

Block polyisocyanate and aqueous coating composition comprising the same

The present invention relates to blocked polyisocyanates and aqueous coating compositions.

The coating film obtained by using the urethane-based paint crosslinked with an isocyanate compound may exhibit very excellent wear resistance, chemical resistance and fouling resistance. In addition, the coating film which uses the unyellowed polyisocyanate which uses aliphatic alicyclic diisocyanate as a raw material of an isocyanate component shows the outstanding weather resistance, and the demand for this is increasing.

In recent years, water-based paints have been attracting attention from the viewpoint of global environment, safety, hygiene, and the like, and methods for aqueous-polyisocyanate compounds for use in water-based paints have been studied. An example of such a method includes introducing a hydrophilic functional group into an isocyanate.

Blocked polyisocyanate has a structure in which isocyanate groups are blocked through a chemical reaction between blocking agents and at least one isocyanate group. Here, the blocking agent is dissociated by heating and the isocyanate group can be regenerated. Such a block polyisocyanate has an advantage of excellent processability.

However, although block polyisocyanates have introduced hydrophilic functional groups and can be used in water-based coatings, the chains are extended as the functional groups are added, and the molecular weight increases significantly as the number of added functional groups is increased, thereby inhibiting the paint properties. It is pointed out as a factor.

Accordingly, there is a continuing need for blocked polyisocyanates that can be used in water-based paints but do not impair paint properties.

The present invention solves the conventional problems as described above, and seeks to provide a block polyisocyanate which is dilutable with aqueous or aqueous, and / or water with improved water dispersibility.

In addition, the present invention is to provide a block polyisocyanate with excellent appearance when applied to automotive water-soluble paints.

The present invention relates to a block polyisocyanate obtained from a polyisocyanate compound and a blocking agent, wherein a first latent isocyanate group in which an isocyanate group is blocked by an active methylene blocking agent and a second latent isocyanate group are blocked by a polyalkylene polyol blocking agent. Provided are a block polyisocyanate containing a third latent isocyanate group in which an isocyanate group is blocked by an isocyanate group and a pyrazole-based blocking agent, and an aqueous coating composition comprising the same.

The blocked polyisocyanate and the aqueous coating composition including the same according to the present invention have improved water dispersibility and can be used diluted with water.

In addition, it can be used to form a coating film excellent in appearance and gloss.

Hereinafter, the present invention will be described in detail.

1. Block Polyisocyanate

The present invention provides blocked polyisocyanates.

Block polyisocyanates of the present invention are obtained from polyisocyanate compounds and blocking agents. Hereinafter, the above configuration will be described in detail.

Polyisocyanate compound

The polyisocyanate compound generically refers to a compound containing at least one isocyanate group. The polyisocyanate compound is not limited thereto, but polyisocyanate compounds such as aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, and aromatic polyisocyanate compounds can be used.

As said aliphatic polyisocyanate compound, trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2, 3- butylene diisocyanate, for example) , 1,3-butylene diisocyanate), 1,5-pentamethylene diisocyanate (PDI), 1,6-hexamethylene diisocyanate (HDI), 2,4,4- or 2,2,4-trimethylhexa Methylene diisocyanate, 2, 6- diisocyanate methyl capate, etc. are mentioned.

Examples of the alicyclic polyisocyanate compound include, but are not limited to, 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, 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), trans, trans-trans, trans, cis-form, cis, cis-form, or mixtures thereof) (H ₁₂ MDI), methylcyclohex Sein diisocyanate (methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate), norbornene diisocyanate (NBDI), bis (isocyanatomethyl) cyclohexane (1,3- or 1,4-bis (isocyanatomethyl) cyclohexane or mixtures thereof) (H ₆ XDI) and the like.

Examples of the aromatic polyisocyanate compound include, but are not limited to, tolylene diisocyanate (2,4- or 2,6-tolylene diisocyanate or mixtures 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'-diphenylmethane diisocyanate or mixtures thereof) (MDI), 4,4'-toluidine diisocyanate (TODI), 4,4'-diphenylether diisocyanate, xylylene diisocyanate (1, 3- or 1,4-xylylene diisocyanate or mixtures thereof (XDI), tetramethylxylylene diisocyanate (1,3- or 1,4-tetramethylxylylene diisocyanate or mixtures thereof) (TMXDI), ω , ω'- diisocyanate-1,4-diethylbenzene, etc. Can be mentioned.

As said polyisocyanate compound, a single compound can be used or 2 or more types can be used together, It is not limited to this.

In one embodiment, the polyisocyanate compound may be preferable because the aliphatic polyisocyanate compound and the alicyclic polyisocyanate compound have excellent weather resistance.

Moreover, it is preferable that it is an aliphatic polyisocyanate compound derived from aliphatic diisocyanate among the said aliphatic polyisocyanate compounds. More specifically, the aliphatic diisocyanate may be preferably 1,6-hexamethylene diisocyanate trimer in terms of weather resistance and industrial availability, but is not limited thereto.

The total equivalent weight of the polyisocyanate compound is suitably 100 to 2000 equivalents, for example 350 to 800 equivalents.

By using the block polyisocyanate in which the content of the isocyanate group is included in the above range and the isocyanate group is blocked by a blocking agent, a coating composition exhibiting excellent physical properties such as appearance and water dispersibility can be provided.

In addition, the polyisocyanate compound may be included in an amount of 15 to 60% by weight based on the total weight of the composition for preparing the blocked polyisocyanate. For example, it may be included in an amount of 30 to 50% by weight, but is not limited thereto. When the coating composition containing the block polyisocyanate in which the content of the polyisocyanate compound is in the above range is used, it is possible to form a coating film having excellent physical properties such as wear resistance, chemical resistance, and stain resistance. In addition, it is possible to provide a coating composition which is blocked by a blocking agent and exhibits excellent water dispersibility.

Blocking agents

The blocking agent used in the present invention forms a new bond with the isocyanate (NCO) in the polyisocyanate compound to block the isocyanate group from reacting with other compounds (eg, resin part). In addition, the block isocyanate formed as described above contains a latent isocyanate group in terms of allowing the blocking agent to dissociate through a reaction such as heating, thereby allowing the isocyanate group to participate in the curing reaction again.

Here, the blocked polyisocyanate may be obtained from 150 to 800 parts by weight of the polyisocyanate compound and 100 to 600 parts by weight of the blocking agent, for example, 300 to 500 parts by weight of the polyisocyanate compound and 200 to 350 parts by weight of the blocking agent. May be, but is not limited thereto.

In particular, some isocyanate groups in the blocked polyisocyanate may be included without blocking. Even more specifically, based on the total isocyanate groups in the polyisocyanate compound, the content of unblocked isocyanate groups is 5 NCO% or less, for example 1 NCO% or less, 0.5 NCO% or less, 0 NCO% (ie Not).

When the content of the polyisocyanate compound and the blocking agent is in the above range, it is possible to provide a desired water-based coating composition, and when the content is less than the above range, the degree of water dispersibility is insignificant. May appear.

The blocking agent includes an active methylene blocking agent, a polyalkylene polyol blocking agent and a pyrazole blocking agent. By using three kinds of blocking agents together as mentioned above, the water dispersibility of the coating composition containing a block isocyanate can be improved, and the physical property of the coating film formed using this can be improved. Hereinafter, the said three types of blocking agents are demonstrated concretely.

<Activated methylene blocking agent>

The active methylene blocking agent is a compound having active hydrogen capable of reacting with isocyanate, but is not limited thereto. For example, dialkyl malonic acid, alkyl acetoacetic acid, 2-ethylheptanoylacetic acid ester, acetyl acetone, n Propanoylacetic acid ester, n-butanoylacetic acid ester, isobutanoylacetic acid ester, n-pentanoylacetic acid ester, n-hexanoylacetic acid ester, or salts thereof, and the like; 1 or more types can be used.

The dialkyl malonic acid is not limited thereto, for example, dimethylmalonic acid, diethylmalonic acid, di (n-propyl) malonic acid, di (isopropyl) malonic acid, di (n-butyl) malonic acid, di (t-butyl) malonic acid, di (2-ethylhexyl) malonic acid, methyl (n-butyl) malonic acid, ethyl (n-butyl) malonic acid, methyl (s-butyl) malonic acid, ethyl (s-butyl Malonic acid, methyl (t-butyl) malonic acid, ethyl (t-butyl) malonic acid, dibenzyl malonic acid, diphenylmalonic acid, benzyl (methyl) malonic acid, ethyl (phenyl) malonic acid, t-butyl ( Phenyl) malonic acid, and the like, and may include one or more selected from the group consisting of these.

The alkyl acetoacetic acid is not limited thereto, for example methyl acetoacetic acid, ethyl acetoacetic acid, n-propyl acetoacetic acid, iso-propyl acetoacetic acid, n-butyl acetoacetic acid, t-butyl acetoacetic acid, benzyl acetoacetic acid, Phenyl acetoacetic acid or these salts, etc. are mentioned.

In one embodiment, the active methylene blocking agent may use diethylmalonic acid or a salt thereof as a compound having active hydrogen that can react with isocyanate.

The active methylene blocking agent may form a bond with an isocyanate at an active methylene position in the compound to block the isocyanate, but the blocking mechanism of the isocyanate is not limited thereto.

The active methylene blocking agent may be included in an amount of 1 to 70 wt%, for example, 20 to 55 wt%, and 30 to 40 wt% based on the total weight of the blocking agent. The active methylene blocking agent may be included in the range below or above the above range, but when included within the above range, it is possible to provide a block polyisocyanate exhibiting excellent physical properties together with the polyalkylene polyol blocking agent and the pyrazole-based blocking agent. .

<Polyalkylene polyol blocking agent>

The polyalkylene polyol blocking agent serves to control the hydrophilicity of the polyisocyanate.

Examples of the polyalkylene polyol blocking agent include, but are not limited to, polyols containing polyoxyethylene groups, more specifically polyethylene glycol (PEG), polytetramethylene oxide (PTMO), polypropylene oxide (PPO), mono It may include one or more selected from alkoxy polyethylene glycol, polyethylene triol, polypropylene triol alone, or a copolymer thereof. The polyalkylene polyol blocking agent may be preferably used polyethylene glycol in view of the hydrophilicity and the chain control of the block isocyanate. In particular, it may be more preferable to use methoxy polyethylene glycol in view of blocking the isocyanate from the side and increasing the number of hydrophilic groups per molecule.

The polyalkylene polyol blocking agent may be used alone or in combination of two or more polyalkylene polyols, the copolymer of the polyalkylene polyol is a block copolymer, a graft copolymer, a star copolymer, or an alternating copolymer Can be.

In addition, the polyalkylene polyol blocking agent may be used that has a number average molecular weight of 200 to 800, for example, may be used from 300 to 700, 400 to 600. When the number average molecular weight of the polyalkylene polyol blocking agent is within the above range, it is possible to improve the efficiency of polyisocyanate blocking. In addition, it can exhibit excellent water dispersibility of the blocked polyisocyanate.

In one embodiment, the coating composition comprising a block polyisocyanate using a blocking polyisocyanate using a blocking agent having a number average molecular weight of 500 as the polyalkylene polyol blocking agent comprises a block polyisocyanate using a blocking agent having a number average molecular weight of 1,000. It confirmed that the physical property of the coating film formed in comparison with the other was excellent.

The polyalkylene polyol blocking agent may be included in 1 to 90% by weight, for example 1 to 70% by weight, 5 to 50% by weight, 10 to 35% by weight, 15 to 30% by weight based on the total weight of the blocking agent. have. The polyalkylene polyol blocking agent may be included in the range below or above the above range, but when included in the above range may provide a block polyisocyanate exhibiting excellent physical properties together with the active methylene-based blocking agent and the pyrazole-based blocking agent. .

<Pyrazole blocking agent>

The pyrazole-based blocking agent serves to improve the storage stability of the blocked polyisocyanate and improve the appearance of the coating film formed of the coating composition including the same.

The pyrazole-based blocking agent is not limited thereto, but may include, for example, one or more selected from the group consisting of pyrazole, 3-methylpyrazole and 3,5-dimethylpyrazole. In one embodiment, block polyisocyanate was prepared using 3,5-dimethylpyrazole as the pyrazole-based blocking agent.

The pyrazole-based blocking agent may be included in 5 to 80% by weight, for example 15 to 60% by weight, 25 to 50% by weight based on the total weight of the blocking agent. The pyrazole-based blocking agent may be included in the range below or above the above range, but when included within the range, it is possible to provide a block polyisocyanate exhibiting excellent physical properties together with an active methylene-based blocking agent and a polyalkylene polyol blocking agent. .

More specifically, the three blocking agents may be used in an amount of 15 to 50 parts by weight of an active methylene blocking agent, 5 to 50 parts by weight of a polyalkylene polyol blocking agent, and 20 to 70 parts by weight of a pyrazole blocking agent. For example, the three blocking agents may be used in an amount of 20 to 25 parts by weight of the active methylene blocking agent, 10 to 25 parts by weight of the polyalkylene polyol blocking agent, and 40 to 50 parts by weight of the pyrazole blocking agent. The three kinds of blocking agents may be used as the weight parts to provide a coating composition having excellent physical properties such as appearance, gloss, adhesion, impact properties as well as water dispersibility.

Formation of Blocked Polyisocyanates

The blocked polyisocyanate of the present invention is not limited thereto, but after the first reaction by mixing the polyisocyanate compound with the active methylene-based and polyalkylene polyol blocking agent in a solvent, the pyrazole-based blocking agent is added to It can be prepared by differential reaction. The first and second reactions of the polyisocyanate compound and the blocking agent may be carried out at 60 to 80 ℃, for example 70 ℃. If the reaction is carried out at 60 to 80 ℃ can block the polyisocyanate with the respective blocking agent in the desired amount. In addition, when the reaction is carried out below the above range, the unblocked isocyanate may be included in excess, for example 5 NCO% or more, based on the total isocyanate group, and the dissociation reaction of the block isocyanate formed when the above reaction is performed above the range. This can be done.

The solvent may be used a solvent conventionally used without limitation, aromatic hydrocarbon solvents such as toluene, xylene, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, ethyl propyl ketone, methyl isobutyl ketone, methyl aryl ketone Ketone solvents such as diisobutyl ketone, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, isopropyl acetate, butyl acetate, methyl cellosolve acetate, cellosolve acetate, butyl cellosolve acetate, carby Ester solvents, such as tall acetate, or alcohol solvents, such as n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, butanediol, or a mixed solvent thereof can be used.

The blocked polyisocyanate may be regenerated by the active methylene-based blocking agent, may contain a urethane group by the polyalkylene polyol blocking agent, and may contain a urea group by the pyrazole-based blocking agent. Block polyisocyanate of the present invention has a technical feature to improve the physical properties of the coating film formed of the water dispersibility and the coating composition used by the three blocking agents and their content ratio.

In addition, the block polyisocyanate may have a weight average molecular weight (Mw) of 1,000 to 5,000, for example, 1,500 to 3,000.

In forming the blocked polyisocyanate, the blocked polyisocyanate may be obtained in a mixed state with the unblocked polyisocyanate compound and / or the three blocking agents remaining and used for blocking the isocyanate. At this time, the resulting mixture is preferably 60 to 80% by weight of solids in the composition, more preferably 65 to 75% by weight. In one embodiment, a mixture with 70% solids is prepared.

The blocked polyisocyanate may exhibit a Gardner viscosity T.

In addition, the blocked polyisocyanate may exhibit a viscosity of 1 to 10 Pa · s at 25 ° C.

When the viscosity of the blocked polyisocyanate is as described above, it may be preferable in view of crosslinking of the resin part and the blocked polyisocyanate.

The blocked polyisocyanate may be used as a curing agent in paint compositions, pressure-sensitive adhesive compositions, adhesive compositions, mold composition, and the like.

2. Aqueous Coating Composition

In particular, the present invention provides an aqueous coating composition comprising the blocked polyisocyanate according to the present invention.

The aqueous coating composition includes a resin portion together with the blocked polyisocyanate.

The resin part may use a resin used in a known aqueous coating composition, but is not limited thereto, for example, acrylic resin, amino resin, polyester resin, epoxy resin, modified resin thereof, and the Resins such as copolymers of monomers constituting the resin or blends thereof.

The blocked polyisocyanate may be included, for example, in an amount of 1 to 30% by weight based on the total weight of the paint composition. In one embodiment, the blocked polyisocyanate was mixed at 10% by weight based on the total weight of the coating composition to prepare a coating composition that forms a coating film having excellent physical properties.

Since the aqueous coating composition according to the present invention includes the blocked polyisocyanate, the water dispersibility is improved and can be diluted with water. In addition, storage stability and weather resistance can be improved, and the coating film formed using the same can exhibit excellent physical properties in appearance, gloss, adhesion, impact, hardness, and the like.

The aqueous coating composition according to the present invention may further include conventional components included in the aqueous coating composition within the range of not impairing the object of the present invention together with the blocked polyisocyanate according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples.

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

<Production of Examples and Comparative Examples>

Block polyisocyanate was prepared in the following manner with the composition shown in Tables 1 and 2.

Category (g) Example One 2 3 4 5 6 HDI trimer (1,6-hexane diisocyanate trimer) 390.5 390.5 439.3 359.3 426.3 172 1,3-butanediol 4.7 4.7 4.6 4.3 4.8 2 Ethyl acetate (1) 147.4 147.4 148.7 148.7 147.4 149.9 Methoxy Polyethylene Glycol (Number Average Molecular Weight 500) 64.3 - 10 64.3 103.2 485 Methoxy polyethylene glycol (number average molecular weight 1,000) - 64.3 - - - - Diethylmalonate 108 108 108 189.4 146 9.5 28% Sodium Methoxide In Methanol 0.8 0.8 1.2 1.2 0.8 0.06 Dimethylpyrazole 148.8 148.8 148.8 113.8 56.6 31.6 Ethyl acetate (2) 135.5 135.5 139.4 119 114.9 149.94 Total 1,000 1,000 1,000 1,000 1,000 1,000

Category (g) Comparative example One 2 3 HDI trimer (1,6-hexane diisocyanate trimer) 359.3 439.3 426.3 1,3-butanediol 4.2 5.1 4.9 Ethyl acetate (1) 147.4 148.7 148.6 Methoxy Polyethylene Glycol (Number Average Molecular Weight 500) 66.3 - 78.7 Methoxy polyethylene glycol (number average molecular weight 1,000) - - - Diethylmalonate 273.8 108.3 - 28% Sodium Methoxide In Methanol 1.6 0.6 - Dimethylpyrazole - 149.4 192.8 Ethyl acetate (2) 148.4 148.6 148.7 Total 1,000 1,000 1000

Example 1

Prepare a 2 L flask, thermometer, agitator, and glassware. In the reactor, the contents of Table 1 were added with HDI trimer, 1,3-butanediol, ethyl acetate (1), methoxy polyethylene glycol, diethylmalonate and sodium methoxide in methanol, and maintained at 70 ° C. under nitrogen atmosphere. It was. When NCO% is 8 to 10%, dimethyl pyrazole is added and maintained at 70 ° C. When NCO% became 0.5% or less, ethyl acetate (2) was added and cooled.

This produced the block polyisocyanate which is 70% of solid content, Gardner viscosity T, and final compound equivalent weight 728.

The measurement of NCO% was performed by the following method.

A sample containing an isocyanate group is weighed into a beaker (250 ml). Then, pipette 25 ml of 0.1N Di-n-butylamine solution into the pipette. Add 25 ml of 1,4-Dioxane (if the polymer does not melt, add 10 ml of reagent grade acetone) and close the flask stopper. The stirring is then continued mechanically for 15 minutes to dissolve the prepolymer. Drop 4 to 6 drops of bromine phenol blue solution and rinse the beaker base with 50 ml of isopropyl alcohol. Titrate with 0.1 N hydrochloric acid until it reaches the yellow end point. Add all the above reagents under the condition of no sample and perform Blank test.

Isocyanate group content is computed as follows.

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

From here,

B: ml of hydrochloric acid consumed in the blank test

V: ml of hydrochloric acid consumed in the sample titration

0.4202: Millie equivalent weight of isocyanate groups

W: weight of sample

Example 2

Prepare a 2 L flask, thermometer, agitator, and glassware. In the reactor, the contents of Table 1 were added with HDI trimer, 1,3-butanediol, ethyl acetate (1), methoxy polyethylene glycol, diethylmalonate and sodium methoxide in methanol, and maintained at 70 ° C. under nitrogen atmosphere. It was. When NCO% is 5 to 10%, dimethyl pyrazole is added and maintained at 70 ° C. When NCO% became 0.5% or less, ethyl acetate (2) was added and cooled.

This produced the block polyisocyanate which is 70% of solid content, Gardner viscosity S, and final compound equivalent weight 750.

Example 3

Prepare a 2 L flask, thermometer, agitator, and glassware. In the reactor, the contents of Table 1 were added with HDI trimer, 1,3-butanediol, ethyl acetate (1), methoxy polyethylene glycol, diethylmalonate and sodium methoxide in methanol, and maintained at 70 ° C. under nitrogen atmosphere. It was. When NCO% is 5 to 10%, dimethyl pyrazole is added and maintained at 70 ° C. When NCO% became 0.5% or less, ethyl acetate (2) was added and cooled.

This produced the block polyisocyanate which is 70% of solid content, Gardner viscosity K, and final compound equivalent weight 708.

Example 4

Prepare a 2 L flask, thermometer, agitator, and glassware. In the reactor, the contents of Table 1 were added with HDI trimer, 1,3-butanediol, ethyl acetate (1), methoxy polyethylene glycol, diethylmalonate and sodium methoxide in methanol, and maintained at 70 ° C. under nitrogen atmosphere. It was. When NCO% is 5 to 10%, dimethyl pyrazole is added and maintained at 70 ° C. When NCO% became 0.5% or less, ethyl acetate (2) was added and cooled.

This produced the block polyisocyanate which is 70% of solid content, Gardner viscosity W, and final compound equivalent weight 789.

Example 5

Prepare a 2 L flask, thermometer, agitator, and glassware. In the reactor, the contents of Table 1 were added with HDI trimer, 1,3-butanediol, ethyl acetate (1), methoxy polyethylene glycol, diethylmalonate and sodium methoxide in methanol, and maintained at 70 ° C. under nitrogen atmosphere. It was. When NCO% was 3% or less, dimethyl pyrazole was added and maintained at 70 ° C. When NCO% became 1.8% or less, ethyl acetate (2) was added and cooled.

This produced the block polyisocyanate which is 70% of solid content, Gardner viscosity N, and final compound equivalent weight 729.

Example 6

Prepare a 2 L flask, thermometer, agitator, and glassware. In the reactor, the contents of Table 1 were added with HDI trimer, 1,3-butanediol, ethyl acetate (1), methoxy polyethylene glycol, diethylmalonate and sodium methoxide in methanol, and maintained at 70 ° C. under nitrogen atmosphere. It was. When NCO% was 5% to 10%, dimethyl pyrazole was added and maintained at 70 ° C. When NCO% became 0.5% or less, ethyl acetate (2) was added and cooled.

This produced the block polyisocyanate which is 70% of solid content, Gardner viscosity Z, and the final compound equivalent weight 1168.

Comparative Example 1

Prepare a 2 L flask, thermometer, agitator, and glassware. In the reactor, the contents of Table 1 were added with HDI trimer, 1,3-butanediol, ethyl acetate (1), methoxy polyethylene glycol, diethylmalonate and sodium methoxide in methanol, and maintained at 70 ° C. under nitrogen atmosphere. It was. When NCO% became 0.5% or less, ethyl acetate (2) was added and cooled.

At this time, the prepared blocked polyisocyanate was obtained with a solid content of 70%, Gardner viscosity R, and final compound equivalent weight of 774.

Comparative Example 2

Without using methoxy polyethylene glycol, dimethyl pyrazole was prepared in the same manner as in Example 1 except that NCO% was added at 8.8 to 9.8%.

At this time, the prepared block polyisocyanate was obtained with solid content 70%, Gardner viscosity P, final compound equivalent weight 703.

Comparative Example 3

Block polyisocyanate was prepared in the same manner as in Example 1, except that dimethyl pyrazole was added when NCO% was 12.3 to 13.5 without using diethylmalonate.

At this time, the prepared blocked polyisocyanate was obtained with a solid content of 70%, Gardner viscosity Q and the final compound equivalent weight 713.

<Preparation of Paint Composition and Evaluation of Physical Properties of Coating Film>

10 parts by weight of each of Examples 1 and 6 and Comparative Examples 1 to 3 prepared above and 90 parts by weight of KCC paint WU3067 were mixed to prepare a coating composition and prepare a specimen that was electrodeposited (0.8 T x 90 mm x 200 mm CR). Board). Apply it to the specimen using AIR SPRAY GUN (air pressure: approx. 4.5 BAR, discharge amount: discharge lever 2.5 wheels OPEN, distance between GUN and specimen: 30cm). Degrease the specimen using IPA. Paint is prepared by diluting to dilution viscosity with prescribed thinner (use 029S). The coating was repeated 2 ~ 2.5 times with the discharge amount to raise the coating film to the prescribed thickness (SETTING: 10 minutes, BAKING TIME: 150 ° C x 20min) to prepare a specimen.

Using the prepared specimen was confirmed the physical properties of the specimen in the following manner.

On the other hand, KCC WU3067 paint is a paint having a solid content of 50 to 55%, a viscosity of 55 to 65 seconds, a specific gravity of 1.2 to 1.27, and a pH of 8.0 to 8.5.

Exterior

The prepared specimens were checked for appearance by Wave Scan DOI. The appearance was confirmed by the LW value. The smaller the value, the brighter the appearance.

Polish

Based on the occurrence of the reflected light at the same angle with respect to the incident light on the surface, the reflectance when the incident light and the reflected light are respectively 60 degrees is measured, and the percentage when the standard surface glossiness is 100 is referred to as 60 degrees glossiness. Using the gloss meter ( BYK Mircro-TRI gross ), select the gloss measurement angle (20 degrees, 60 degrees, 85 degrees) after calibration before use. Place the gloss meter on the specimen and measure the 60 degree gloss. Higher values indicate better gloss.

Water dispersibility

Each of Examples 1-6 and Comparative Examples 1-3 prepared was mixed with DIW in a weight ratio of 1: 5, and the solution state thereafter was visually observed.

O was mixed, and there was no sediment, and the state with precipitate was evaluated as X.

Adhesion

Draw a checkerboard line in the center area with 11 parallel lines each 1 mm apart with 100 square scales. The NICHIBAN tape, 2 inches wide, is tightly pressed against the cross-cut area to prevent air trapping. Hold the tape by hand and pull it towards you at an angle of 45 degrees, and judge it according to the attachment regulations of KS M 5000-3341.

Impact

Place the specimen on the bottom and use a 1/2 inch weight to drop the weight from the specified height. The test is repeated with the height increased until cracks form at the edges of the dug circular due to impact.

Hardness

Rub the pencil core at right angles to a 1000 mesh sandpaper to make the pencil core at right angles, and then remove the sandpaper on the pencil core with a soft cloth. Apply a load of approximately 500 g upwards from the body at an angle of 45 degrees to the specimen. Place a ruler and draw five parallels 2 cm long. At this time, draw the hexagonal shape of the pencil while turning it properly so that the right angled circular pencil core is not used twice. When scratched with a pencil under a load of 100 g, the coating film is scratched. If no trace remains, the same evaluation is made with a pencil of high hardness. The hardness of the pencil at the time point at which the substrate is revealed is indicated by hardness. Repeat the same evaluation three times and record the average.

division Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Preparation Example 5 Preparation Example 6 combination varnish 90 90 90 90 90 90 Example 1 10 - - - - - Example 2 - 10 - - - - Example 3 - - 10 - - - Example 4 - - - 10 - - Example 5 - - - - 10 - Example 6 - - - - - 10 Total 100 100 100 100 100 100 Properties Exterior 7 7 9 9 10 12 Polish 85 83 83 82 80 78 Water dispersibility O 0 0 0 0 0 Attach M-1.5 M-1.5 M-1.5 M-1.5 M-1.5 M-1.5 Impact 50 cm or more 50 cm or more 50 cm or more 45 cm or more 45 cm or more 45 cm or more Hardness HB HB HB HB HB HB

division Comparative Production Example 1 Comparative Production Example 2 Comparative Production Example 3 combination varnish 90 90 90 Comparative Example 1 10 - - Comparative Example 2 - 10 - Comparative Example 3 - - 10 Total 100 100 100 Properties Exterior 17 15 14 Polish 61 75 69 Water dispersibility O X O Attach M-2.5 M-2.5 M-1.5 Impact 45 cm or more 40 cm or more 45 cm or more Hardness 2B B B

As can be seen in Tables 3 and 4, the pyrazole-based blocking agent is effective in improving the glossiness of the paint, the malonate-based blocking agent is effective in improving the appearance, impact resistance when using the equivalent polyalkylene polyol, It may adversely affect the adhesion and appearance. In addition, it was confirmed that the water dispersibility is improved by using a polyethylene glycol-based blocking agent.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, and such modifications and modifications belong to the appended claims.

Claims (7)

As a block polyisocyanate obtained from a polyisocyanate compound and a blocking agent,
A first latent isocyanate group in which an isocyanate group is blocked by an active methylene blocking agent, a second latent isocyanate group in which an isocyanate group is blocked by a polyalkylene polyol blocking agent, and an agent in which an isocyanate group is blocked by a pyrazole-based blocking agent Block polyisocyanates containing 3 latent isocyanate groups.
The method according to claim 1,
And said blocking agent comprises 15 to 50 parts by weight of said active methylene-based blocking agent, 5 to 50 parts by weight of said polyalkylenepolyol blocking agent and 20 to 70 parts by weight of said pyrazole-based blocking agent.
The method according to claim 1,
The active methylene blocking agent is dialkyl malonic acid, alkyl acetoacetic acid, 2-ethylheptanoyl acetate ester, acetyl acetone, n-propanoyl acetate ester, n-butanoyl acetate ester, isobutanoyl acetate ester, n- Block polyisocyanate comprising at least one member selected from the group consisting of pentanoylacetic acid ester and n-hexanoylacetic acid ester.
The method according to claim 1,
The polyalkylene polyol blocking agent may be polyethylene glycol (PEG), polytetramethylene oxide (PTMO), polypropylene oxide (PPO), monoalkoxy polyethylene glycol, polyethylene triol, polypropylene triol alone, or a copolymer thereof. Block polyisocyanate containing one or more selected from the group consisting of.
The method according to claim 1,
The polyalkylene polyol blocking agent is a block polyisocyanate having a number average molecular weight of 200 to 800.
The method according to claim 1,
Block polyisocyanate obtained from 150 to 800 parts by weight of the polyisocyanate compound and a total of 100 to 600 parts by weight of the blocking agent.
An aqueous coating composition comprising the blocked polyisocyanate according to any one of claims 1 to 6.