KR102143210B1 - Reversibly self-healable polymer networks including hindered urea bonds and use thereof - Google Patents

Abstract

The present invention relates to preparation and use of a reversible self-healing poly(urethane acrylate) network containing hindered urea bonds capable of self-healing of a damaged portion of a coated surface generated by scratch, or the like. Particularly, the present invention relates to a self-healing resin composition capable of forming a thermally reversible network including: a polymer resin containing a hydroxyl group at the end of a side chain; and a thermally reversible multi-functional additive, which has a plurality of -OH groups at the end of the molecular structure, and is prepared through a reaction between a multi-functional isocyanate containing at least two hindered urea structures in the molecular structure and end-capped with at least two isocyanate groups and H-(O-CH_2-CH_2)_n-OH (wherein n is an integer of 1-10) as a chain extending agent. The present invention also relates to a reversible self-healing network formed by mixing the composition with a curing agent and curing the resultant mixture, and a method for producing the same.

Description

Reversible self-healable polymer networks including hindered urea bonds and use thereof

The present invention relates to the manufacture and use of a thermoreversible self-healing network including a hindered urea bond capable of self-healing a damaged portion of a coating surface caused by scratches or the like.

More specifically, a polymer resin containing a hydroxyl group at the end of the side chain; And a polyfunctional isocyanate containing two or more hindered urea structures in the molecular structure and containing two or more isocyanate groups at the terminal and H-(O-CH ₂ -CH ₂ )n-OH (n is 1 to 10 A self-healing resin composition characterized in that it includes a thermoreversible multifunctional additive having a plurality of -OH groups at the end of the molecular structure produced by reaction with an integer), and a thermoreversible network is formed by mixing and curing it with a curing agent. It relates to a self-healing reversible self-healing network formed and a manufacturing method thereof.

Physical damage, such as scratches, which occurs on coatings of transport equipment and electronic products, corrodes the metal substrate protected by the coating, causing functional damage to the substrate, as well as remarkably deteriorating the appearance of the product. The most ideal way to respond to this is to manufacture a coating material with high physical properties that can completely exclude physical damage, but in a commercial organic coating system that generally employs an acrylic polymer network system, this is almost impossible from a material and economic point of view. Do. For this reason, industry and academia have been researching various self-healing coating systems that can recover physical damage by external stimuli such as heat and light. Among them, resins including thermoreversible hindered urea bonds have a high dynamic crosslinking system. It is highly valuable as a self-healing technology suitable for industrial fields such as transportation equipment, electronics and architecture that require mechanical properties.

In the prior art related to the manufacturing method of self-healing polyurethane, the step of forming a polyurea prepolymer by reacting an aliphatic diisocyanate with tertiary butal diamine, and a polymer by reacting a crosslinking agent to the polyurethane prepolymer and polyurea prepolymer. Korean Patent Laid-Open Publication No. 2018-0078834, which relates to a method for producing a self-healing polymer comprising the step of forming, and a self-healing obtained by curing a mixture containing a polyurethane prepolymer and anhydrosugar alcohol There is Korean Laid-Open Patent Publication No. 2018-0026417 for sexual polyurethane.

In general, since the self-healing performance of a reversible self-healing coating system is determined by the fluidity of a polymer, it is very difficult to achieve high mechanical properties and self-healing performance at the same time. In addition, most of the reversible self-healing coating systems reported to date are prepared by preparing a multifunctional group curing agent with reversible self-healing properties and chemically reacting it with a resin containing a reactive functional group. This method increases the composition of the self-healing curing agent. Accordingly, the curing degree of the polymer system also increases rapidly at the same time, causing a deterioration in self-healing performance.

Korean Patent Application Publication No. 2018-0078834 Korean Patent Application Publication No. 2018-0026417

The present invention was developed to solve the above problems, maximizes the scratch resistance of the coating, and when the network structure is damaged, a self-healing composition suitable for a self-healing function and an industrial coating process, a clear coat having a self-healing function using the same, and It is an object to provide a method for manufacturing the same.

In the present invention, in order to solve the above problems, polyfunctional isocyanates containing two or more hindered urea structures in the molecular structure and two or more isocyanate groups at the ends are used as chain extenders, ethylene glycol (ethylene glygol), tetraethylene glycol ( tetraethylene glycol) including H-(O-CH ₂ -CH ₂ )n-OH (n is an integer of 1 to 10) by reaction with a compound having a chemical structure at the end of the molecular structure It provides a multifunctional crosslinking agent having an -OH group.

In addition, in the present invention, a clear coat binder composition obtained by combining a polyfunctional crosslinking agent having a plurality of -OH groups at the end of the molecular structure and a polyacrylate copolymer resin containing a hydroxyl group at the end of the side chain, which is an acrylic binder resin, in a certain ratio, and It provides a method of manufacturing.

In addition, the present invention provides a self-healing reversible self-healing network formed by combining a clear coat binder composition with a polyfunctional isocyanate curing agent in a certain ratio and chemically reacting, and a method of manufacturing the same.

The self-healing poly(urethane acrylate) composition comprising a hindered-urea adduct according to the present invention utilizes the reversible reaction of hindered urea bonds that occur in proportion to high temperature, such as scratches, etc. It has the advantage of self-healing of coating damage.

In addition, the self-healing poly(urethane acrylate) composition according to the present invention contains a chain extender having various lengths of ethylene oxide repeating units, so that the desired physical properties such as solvent resistance, solubility and hardness of the final coating can be varied in the coating process. Can be adjusted.

In addition, the clear coat using the self-healing poly(urethane acrylate) composition according to the present invention can form an ether-based coating layer with excellent mechanical properties while securing fast self-healing performance. There is an advantage that can be applied.

1 is a conceptual diagram illustrating a self-healing mechanism of a thermoreversible self-healing network material using a hindered urea coupling according to an embodiment of the present invention.
2 is an analysis of the self-healing characteristics (surface self-healing by exposure at 75° C. for 12 hours) for the scratch of the self-healing coating material prepared according to an embodiment of the present invention using a scratch tester. It shows the results.
3 is a result of quantitatively analyzing the mechanical properties of a self-healing coating material manufactured according to an embodiment of the present invention using an indentation device.

Hereinafter, the present invention will be described in detail. Terms and words used in the specification and claims should not be construed as limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. Based on the principle that the present invention should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

The term "self-healing" as used throughout this specification is the ability to heal (recover/repair) the damaged material to its original state automatically and autonomously without any external interference in the broad sense. By means of agreement, it means that the damage caused by the external force can be restored to its original state to some extent.

The reversible self-healing according to the present invention is the damage caused by the reversible reaction of the hindered-urea adduct included in the material when cracking or micro-damaging the surface of the material. It means recovery.

In the present invention, in order to solve the above problems, a polymer resin containing a hydroxyl group at the end of the side chain; A polyfunctional isocyanate containing two or more hindered urea structures in the molecular structure and containing two or more isocyanate groups at the terminal and H-(O-CH ₂ -CH ₂ )n-OH (n is 1 to 10 A thermoreversible polyfunctional additive having a plurality of -OH groups at the ends of the molecular structure produced by reaction with a compound having a chemical structure of integer); And it provides a self-healing resin composition characterized in that it is possible to form a thermoreversible network including a multifunctional isocyanate curing agent.

In the self-healing resin composition according to an embodiment of the present invention, the polymer resin may have a chemical structure represented by Formula 1 below.

<Formula 1>

In Formula 1, m is 0 to 1,000, n is 1 to 1,000, o is an integer of 0 to 100, p is an integer of 0 to 100, q is an integer of 0 to 100, and r is 0 to 100 Is an integer of, s is an integer of 0 to 100, but o and r are not 0 at the same time.

The polymer resin according to an embodiment of the present invention is typically a polyacrylate resin, a polymethacrylate resin, and a homopolymer or a copolymer resin containing various acrylate and methacrylate monomers, and a clear coat for automobile paints As a resin that can be used as a polyfunctional isocyanate curing agent, it is preferable to contain a hydroxyl group (-OH) group at the end of the side chain of the molecular structure.

In the self-healing resin composition according to an embodiment of the present invention, the hindered urea structure may be formed by a urea formation reaction through a 1:2 equivalent reaction of the amine group of the hindered diamine and the isocyanate group of the polyfunctional isocyanate. .

The hindered urea according to an embodiment of the present invention is characterized in that it contains two or more hindered urea functional groups in a molecular structure in a structure in which a large substituent is attached near an amine group.

According to an embodiment of the present invention, the hindered diamine is N,N'-di-tertbutylethylenediamine (N,N'-di-tertbutylethylenediamine) or bis(2,2,6,6-tetramethyl-4 -Piperidyl) sebacate (bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate) may be any one, and the polyfunctional isocyanate is aliphatic, aromatic, alicyclic, or aromatic Any one of the aliphatic compounds may contain two or more isocyanate groups in the molecular structure.

According to an embodiment of the present invention, the aliphatic isocyanate polyfunctional isocyanate compound includes ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HMDI), octamethylene diisocyanate, nonamethylene diisocyanate, Dodecamethylene diisocyanate, 2,2-dimethylpentane diisocyanate, 2,2,4-trimethyl hexamethylene diisocyanate, decamethylene diisocyanate, butene diisocyanate, 1,3-butadiene-1,4-diisocyanate, 2 ,4,4-trimethyl hexamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanate methylcaproate, bis( 2-isocyanate ethyl) fumarate, bis (2-isocyanate ethyl) carbonate, 2-isocyanate ethyl-2,6-diisocyanate hexanoate, 1,3,6-hexamethyrene triisocyanate, 1,8 -Diisocyanato-4-isocyanatomethyl octane, 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyl octane, bis(isocyanatoethyl) carbonate, bis(isocya) Nattoethyl) ether, 1,4-butylene glycol dipropyl ether-ω,ω'-diisocyanate, lysine diisocyanato methyl ester, lysine triisocyanate, 2-isocyanatoethyl-2,6-diisocyanato ethyl -2,6-diisocyanato hexanoate, 2-isocyanato propyl-2,6-diisocyanato hexanoate, xylylene diisocyanate, bis (isocyanatoethyl) benzene, bis (isocyanato) Propyl) benzene, α,α,α',α'-tetramethyl xylylene diisocyanate, bis (isocyanato butyl) benzene, bis (isocyanatomethyl) naphthalene, bis (isocyanatomethyl) diphenyl ether , Bis(isocyanatoethyl) phthalate, 2,6-di(isocyanatomethyl) furan, 1,3,-bis(6-isocyanatohexyl)-uretidine-2,4-dione, 1 ,3,5-tris (6-isocyanato hexyl) isocyanurate at least one aliphatic selected from the group consisting of It may be a isocyanate.

According to an embodiment of the present invention, the alicyclic isocyanate polyfunctional isocyanate compound is isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene di. Isocyanate, bis(2-isocyanate ethyl)-4-cyclohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, 2,6-norbornane diisocyanate, 2,2-dimethyl dicy Chlohexylmethane diisocyanate, bis(4-isocyanato-n-butylidene) pentaerythritol, dimer acid diisocyanate, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-5-iso Cyanatomethyl-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2,2,1] -Heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-5-isocyanatomethyl-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-2-( 3-isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-(2- Isocyanatoethyl)-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-(2-isocyanatoethyl)-bicyclo[ 2,1,1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-5-(2-isocyanatoethyl)-bicyclo[2,1,1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-6-(2-isocyanatoethyl)-bicyclo[2,2,1]-heptane, norbornane bis(isocyanatomethyl) ) It may be one or more alicyclic isocyanates selected from the group consisting of.

According to an embodiment of the present invention, the aromatic aliphatic isocyanate polyfunctional isocyanate compound is 1,3-bis (isocyanatomethyl) benzene (m-xylene diisocyanate, m-XDI), 1,4-bis (iso Cyanatomethyl) benzene (p-xylene diisocyanate, p-XDI), 1,3-bis (2-isocyanato propan-2-yl) benzene (m-tetramethyl xylene diisocyanate, m-TMXDI), 1 ,4-bis(2-isocyanatopropan-2-yl)benzene (p-tetramethyl xylene diisocyanate, p-TMXDI), 1,3-bis(isocyanatomethyl)-4-methylbenzene, 1, 3-bis(isocyanatomethyl)-4-ethylbenzene, 1,3-bis(isocyanatomethyl)-5-methylbenzene, 1,3-bis(isocyanatomethyl)-4,5-dimethylbenzene , 1,4-bis(isocyanatomethyl)-2,5-dimethylbenzene, 1,4-bis(isocyanatomethyl)-2,3,5,6-tetramethylbenzene, 1,3-bis( Isocyanatomethyl)-5-tert-butyl benzene, 1,3-bis(isocyanatomethyl)-4-chlorobenzene, 1,3-bis(isocyanatomethyl) -4,5-dichlorobenzene, 1 ,3-bis(isocyanatomethyl)-2,4,5,6-tetrachlorobenzene, 1,4-bis(isocyanatomethyl)-2,3,5,6-tetrachlorobenzene, 1,4 -Bis(isocyanatomethyl)-2,3,5,6-tetrabromobenzene, 1,4-bis(2-isocyanatoethyl)benzene, 1,4-bis(isocyanatomethyl) naphthalene It may be one or more aromatic aliphatic isocyanates selected from the group consisting of.

In the self-healing resin composition according to an embodiment of the present invention, the multifunctional isocyanate is more preferably any one of hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI).

According to an embodiment of the present invention, the polyfunctional isocyanate may have a structure represented by the following Formulas A1 to D1.

<Formula A1>

<Formula B1>

<Formula C1>

<Formula D1>

According to an embodiment of the present invention, in the reaction of the polyfunctional isocyanate and a compound having a chemical structure of H-(O-CH ₂ -CH ₂ )n-OH (n is an integer of 1 to 10) as a chain extender The thermoreversible polyfunctional additive having a plurality of -OH groups at the ends of the molecular structure produced by the above may have structures of the following Formulas A2 to D2.

<Formula A2>

<Formula B2>

<Formula C2>

<Formula D2>

In Formulas A2 to D2, n is an integer of 1 to 10.

The thermoreversible multifunctional additive including a hindered urea bond such as Formula A2 and Formula B2 may improve mechanical properties and improve storage stability. In addition, since it contains a chemical structure of H-(O-CH ₂ -CH ₂ )n-OH (n is an integer of 1 to 10) as a chain extender, crosslinking can be started even at a lower temperature.

In particular, the thermoreversible polyfunctional additive including a long alkyl chain derived from hexamethylene diisocyanate, such as Formula C2 and Formula D2, has the advantage of excellent chain movement and excellent solubility, and the formula A2 and Formula C2 The same hindered urea bond has better solubility than the above Chemical Formulas B2 and D2, but the reversible reaction of hindered urea is superior in Chemical Formulas B2 and D2 in which a larger substituent is attached to the amine group position.

The compound having a chemical structure of H-(O-CH ₂ -CH ₂ )n-OH (n is an integer of 1 to 10) as the chain extender according to the present invention is more preferably ethylene glycol: EG) or triethylene glycol (TEG) or polyethylene glycol 400 (poly(ethyleneglycol): PEG) may contain at least two or more ether groups in the molecular structure.

In the preparation of the thermoreversible polyfunctional additive according to an embodiment of the present invention, H-(O) having an isocyanate group and an ether group basically of a hindered urea compound containing two or more isocyanate groups at the ends of the formulas A1 to D1. For a stoichiometric reaction of a hydroxyl group of a compound having a chemical structure of -CH ₂ -CH ₂ )n-OH (n is an integer of 1 to 10), it is preferable to control its content. For example, in the case of a hindered urea bond containing two isocyanate groups as shown in Formulas A1 to D1, it is preferable to use a crosslinking agent equivalent to 1/2 of the hydroxyl groups of the ether-based resin for crosslinking. In addition, in the case of a hindered urea bond containing three isocyanate groups, it is preferable to use a crosslinking agent equivalent to 1/3 of the hydroxyl groups of the ether-based resin for crosslinking, and in the case of a hindered urea bond containing four isocyanate groups, the ether-based It is preferable for crosslinking to use a crosslinking agent in the amount of 1/4 equivalent of the hydroxyl groups of the resin.

Thermoreversible polyfunctional additives such as Formulas A2 to D2 according to an embodiment of the present invention improve solubility in a solvent by means of ether repeating units included in the molecular structure, so that it is easy to use in a commercial clear coat.

In addition, the present invention provides a clear coat having a scratch self-healing function in which the self-healing composition including the hindered urea bond is formed by a crosslinking reaction with a clear coat crosslinking agent.

At this time, the crosslinking reaction may proceed by reaction of the hydroxyl group contained at the end of the thermoreversible polyfunctional additive including the hindered urea bond and the isocyanate of the clear coat crosslinking agent, and the composition includes known additives, for example, a binding inhibitor, Antistatic agents, antioxidants, biostabilizers, chemical molding agents, release agents, flame retardants, lubricants, coloring agents, flow improvers, fillers, lubricants, adhesion promoters, catalysts, light stabilizers, optical brighteners, organophosphorus compounds, oils, dyes, Impact modifiers, reinforcing agents, reinforcing fibers, weathering agents and plasticizers may additionally be used as desirable components such as.

In addition, the present invention provides a method of manufacturing a self-healing resin composition comprising a hindered urea bond.

A method of preparing a self-healing resin composition according to an embodiment of the present invention includes preparing a multifunctional isocyanate containing two or more hindered urea structures in the molecular structure and containing two or more isocyanate groups at the terminal; Thermoreversible polyfunctionality having a plurality of -OH groups at the ends of the molecular structure by reaction of the polyfunctional isocyanate with H-(O-CH ₂ -CH ₂ )n-OH (n is an integer of 1 to 10) as a chain extender Preparing an additive; And a step of preparing a coating composition of mixing the thermoreversible polyfunctional additive, a polymer resin containing a hydroxyl group at the end of the side chain, and a polyfunctional isocyanate curing agent.

In addition, in the present invention, the preparation step of the composition for coating a self-healing resin prepared according to the method; A coating composition application step of applying the coating composition to a substrate; And it provides a method of forming a scratch self-healing clear coat comprising the step of forming a coating layer crosslinking the applied coating composition.

In this case, the substrate may be a steel plate for automobiles, and may further include a primer and a base coat.

Hereinafter, implementation examples and examples of the present application will be described in detail so that those with general knowledge in the technical field to which the present application pertains can be easily implemented, as shown in the accompanying drawings. In particular, the technical idea of the present invention and its core configuration and operation are not limited by this. In addition, the content of the present invention may be implemented in various different types of equipment, and is not limited to the implementation examples and examples described herein.

<Production of polyfunctional isocyanate>

The polyfunctional isocyanate compound having two or more isocyanate groups according to an embodiment of the present invention and including a hindered urea structure in the molecular structure may have a chemical structure of the following Formulas A1 to D1, and a more specific preparation method is as follows. same.

<Preparation of Formula A1 Compound>

The compound of Formula A1 is N,N'-di-tertbutylethylenediamine (N,N'-di-tertbutylethylenediamine) after dissolving isoporone diisocyanate (IPDI) in methyl ether ketone (MEK). Was slowly added dropwise at 2:1 equivalent, and then reacted at 35° C. for 2 hours to prepare.

<Preparation of the compound of formula B1>

The compound of formula B1 is bis(2,2,6,6-tetramethyl-4-piperidyl) seba after dissolving isoporone diisocyanate (IPDI) in methyl ether ketone (MEK). Cate (bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate) was slowly added dropwise at 2:1 equivalent, and then reacted at 35° C. for 2 hours to prepare.

<Preparation of Formula C1 Compound>

The compound of Formula C1 is hexamethylene diisocyanate (HMDI) dissolved in methyl ether ketone (MEK) and then N,N'-di-tertbutylethylenediamine (N,N'-di-tertbutylethylenediamine) was dissolved. It was slowly added dropwise at 2:1 equivalent and then reacted at 35° C. for 2 hours to prepare.

<Preparation of Formula D1 Compound>

Formula D1 compound is obtained by dissolving hexamethylene diisocyanate (HMDI) in methyl ether ketone (MEK) and bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate ( bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate) was slowly added dropwise at 2:1 equivalent and then reacted at 35° C. for 2 hours to prepare.

<Preparation of thermoreversible multifunctional additive>

The thermoreversible polyfunctional additive including a hindered urea bond in the molecular structure according to an embodiment of the present invention may have a chemical structure of the following Chemical Formulas A2 to D2, and a more specific preparation method is as follows.

Preparation Example 1: Preparation of Compound A2

However, in Formula A2, n is an integer of 1 to 10.

In methyl ether ketone (MEK), ethylene glycol (EG), tetra ethylene glycol (TEG) or polyethylene glycol (PEG) is added to the above formula. After dissolving 2 equivalents of the diisocyanate compound containing the hindered urea structure of A-1, dibutyltin dilaurate (DBTDL) was mixed in a weight ratio of 1 wt%, and the hindered urea structure of A-1 was It is slowly added dropwise to the containing diisocyanate compound, and the reaction proceeds at 70° C. for 2 hours, and when the reaction is completed, the reaction product is dried to form a thermoreversible crosslinking agent DA-IPDI-EG or DA-IPDI-TEG or DA-IPDI-PEG. Was obtained.

Preparation Example 2: Preparation of Compound B2

<Formula B2>

In Formula B2, n is an integer of 1 to 10.

In methyl ether ketone (MEK), ethylene glycol (EG), tetra ethylene glycol (TEG) or polyethylene glycol (PEG) is added to the above formula. After dissolving 2 equivalents of the diisocyanate compound containing the hindered urea structure of B-1, dibutyltin dilaurate (DBTDL) was mixed in a weight ratio of 1 wt%, and the hindered urea structure of B-1 was It is slowly added dropwise to the containing diisocyanate compound, and the reaction proceeds at 70° C. for 2 hours, and when the reaction is completed, the reaction product is dried to form a thermoreversible crosslinking agent, TMP-IPDI-EG or TMP-IPDI-TEG or TMP-IPDI-PEG. Was obtained.

Preparation Example 3: Preparation of Compound C2

<Formula C2>

In Formula C2, n is an integer of 1 to 10.

In methyl ether ketone (MEK), ethylene glycol (EG), tetra ethylene glycol (TEG) or polyethylene glycol (PEG) is added to the above formula. After dissolving 2 equivalents of the diisocyanate compound containing the hindered urea structure of C-1, dibutyltin dilaurate (DBTDL) was mixed in a weight ratio of 1 wt%, and the hindered urea structure of C-1 was It is slowly added dropwise to the containing diisocyanate compound, and the reaction proceeds at 70° C. for 2 hours, and when the reaction is completed, the reaction product is dried to form a thermoreversible crosslinking agent DA-HDI-EG or DA-HDI-TEG or DA-HDI-PEG. Was obtained.

Preparation Example 4: Preparation of Compound D2

<Formula D2>

In Formula D2, n is an integer of 1 to 10.

In methyl ether ketone (MEK), ethylene glycol (EG), tetra ethylene glycol (TEG) or polyethylene glycol (PEG) is added to the above formula. After dissolving 2 equivalents of the diisocyanate compound containing the hindered urea structure of D-1, dibutyltin dilaurate (DBTDL) was mixed in a weight ratio of 1 wt%, and the hindered urea structure of D-1 was It is slowly added dropwise to the containing diisocyanate compound, and the reaction proceeds at 70° C. for 2 hours, and when the reaction is completed, the reaction product is dried to form a thermoreversible crosslinking agent, TMP-HDI-EG or TMP-HDI-TEG or TMP-HDI-PEG. Was obtained.

< Hindered Urea Combined Thermoreversible Crosslinking reaction OK>

First, the reversible crosslinking reaction of the hindered urea bond was confirmed using an infrared spectroscopy.

That is, the reversible crosslinking reaction of the self-healing coating material by the hindered urea was qualitatively analyzed by confirming the C=O urea peak at 150°C with an infrared spectroscopy. The sample was heated from room temperature to 150° C. at 10° C./min and held for 30 minutes so that the reversible crosslinking reaction of hindered urea could sufficiently occur.

In addition, in order to quantitatively analyze the reversible crosslinking reaction of hindered urea, it was confirmed using H-NMR.

That is, in order to cause the reversible crosslinking reaction by the hindered urea of the self-healing coating material, the urea bond is broken and then attached, and isocyanate is generated.In this case, in order to confirm the isocyanate generated by breaking, it was allowed to react with a hydroxyl group arbitrarily. The preparation of the thermoreversible crosslinking agent (DA-IPDI-EG) of Preparation Example 1 was dissolved in chloroform, and 2 equivalents of nucleic acidol were reacted at 60° C. and quantitatively analyzed using ¹ H-NMR over time. The standard in ¹ H-NMR is shown in Table 1 below by comparing the hydrogen area of the alkyl group next to the hydroxyl group of the unreacted nucleic acidol and the alkyl group next to the hydroxyl group of the nucleic acidol reacted with the isocyanate.

¹ H-NMR reversible crosslinking reaction confirmation Alkyl group of unreacted nucleic acidol Alkyl group of reacted nucleic acidol Change (%) 13 hours later 4 0.5 11.0 After 20 hours 4 0.6 13.0 After 37 hours 4 0.75 15.8

<Manufacture of thermal reversible self-healing network coating material>

A thermally reversible crosslinking agent including a hindered urea bond according to Preparation Examples 1 to 4 in the molecular structure was mixed with a commercial binder resin, and a crosslinking agent was added as much as the equivalent of the total hydroxyl groups to prepare a coating composition. It is summarized in Table 2. The commercial binder resin and crosslinking agent used are T30 clearcoat products and Desmodur N3300 (hexamethylene diisocyanate trimer, hexamethylene diisocyanate trimer) provided by Norubi Chemical, respectively.

Composition (OH%) Crosslinking agent content
(Desmodur N3300) Self-healing crosslinking agent Commercial binder resin Example 1 10 (DA-IPDI-EG) 90 1 equivalent Example 2 30 (DA-IPDI-EG) 70 1 equivalent Example 3 10 (DA-IPDI-TEG) 90 1 equivalent Example 4 30 (DA-IPDI-TEG) 70 1 equivalent Example 5 10 (DA-IPDI-PEG) 90 1 equivalent Example 6 30 (DA-IPDI-PEG) 70 1 equivalent Example 7 10 (TMP-IPDI-EG) 90 1 equivalent Example 8 30 (TMP-IPDI-EG) 70 1 equivalent Example 9 10 (TMP-IPDI-TEG) 90 1 equivalent Example 10 30 (TMP-IPDI-TEG) 70 1 equivalent Example 11 10 (TMP-IPDI-PEG) 90 1 equivalent Example 12 30 (TMP-IPDI-PEG) 70 1 equivalent Example 13 10 (DA-HDI-EG) 90 1 equivalent Example 14 30 (DA-HDI-EG) 70 1 equivalent Example 15 10 (DA-HDI-TEG) 90 1 equivalent Example 16 30 (DA-HDI-TEG) 70 1 equivalent Example 17 10 (DA-HDI-PEG) 90 1 equivalent Example 18 30 (DA-HDI-PEG) 70 1 equivalent Example 19 10 (TMP-HDI-EG) 90 1 equivalent Example 20 30 (TMP-HDI-EG) 70 1 equivalent Example 21 10 (TMP-HDI-TEG) 90 1 equivalent Example 22 30 (TMP-HDI-TEG) 70 1 equivalent Example 23 10 (TMP-HDI-PEG) 90 1 equivalent Example 24 30 (TMP-HDI-PEG) 70 1 equivalent Comparative Example (T30) Commercial polyacrylate clear coat 1 equivalent

The substrate used for the coating was a CR steel sheet for automobiles, and a primer and a base coat were sequentially coated with a Drawdown Bar Coater to a thickness of about 50 μm, respectively.

The self-healing network coating containing the thermoreversible crosslinking agent containing the hindered urea bonds of Examples 1 to 24 in the molecular structure was coated on the substrate with a drawdown bar coating method with a thickness of 50 μm, and then in a reflux oven at 110° C. for 30 minutes. The film was formed to prepare a clear coat.

<Physical property evaluation: scratch Self-healing characteristics evaluation>

The scratch self-healing process was analyzed by temperature using a Scratch Tester by mixing the clearcoat resin and commercial resin prepared according to Examples 1 to 24 and Comparative Examples according to an embodiment of the present invention by ratio. The scratch width was 40μm, the width was 10μm, and the force applied to the film was 5mN. After 24 hours at 25℃, 55℃, or 75℃, the width and depth of the scratch were observed with Atomic Force Microscopy (AFM), and the temperature was applied. The width and depth of the scratches were compared, and the results are shown in Table 3. As can be seen from Table 3, a self-healing phenomenon was observed in the network coating containing hindered urea capable of reversible reaction when the scratch was generated with a force of 5 mN.In particular, the reversible reaction of the hindered urea was higher than the glass transition temperature. Excellent scratch self-healing was observed at the high temperature that occurred.

Fig. 2 shows the results of comparing before and after scratching at 75°C with an optical microscope. The network coating containing hindered urea exhibited excellent self-healing, whereas the commercial clear coat (Comparative Example) used as a control could not visually see the self-healing phenomenon.

Self-healing temperature (℃) Sample name Width (㎛) Depth (㎛) Healing Efficiency (%) Before healing After healing Before healing After healing Width Depth 25 Comparative example 2.39 2.27 0.86 1.02 5.02 0 Example 1 2.87 2.79 1.75 1.56 2.79 10.86 Example 2 2.2 2.07 0.88 0.86 5.91 2.27 Example 3 2.49 2.4 1.04 1.03 3.61 0.96 Example 4 2.62 2.54 1.18 1.37 3.05 0 Example 5 2.44 1.88 1.52 1.4 22.95 7.89 Example 6 2.38 2.11 1.3 1.12 11.34 13.85 Example 7 2.37 2.27 1.25 1.24 4.22 0.8 Example 8 2.39 2.27 0.96 0.96 5.02 0 Example 9 2.29 2.15 1.14 1.12 6.11 1.75 Example 10 2.02 1.9 1.23 1.2 5.94 2.44 Example 11 2.5 2.1 1.15 0.98 16 14.78 Example 12 2.7 2.3 1.21 1.01 14.81 16.53 Example 13 2.07 1.9 1.18 1.08 8.21 8.47 Example 14 2.21 2.03 0.99 0.89 8.14 10.1 Example 15 2.32 2.13 1.05 0.96 8.19 8.57 Example 16 2.12 1.97 1.2 1.08 7.08 10. Example 17 2.38 1.88 1.34 1.22 21.01 8.96 Example 18 2.4 2.1 1.22 1.02 12.5 16.39 Example 19 2.17 2.06 1.22 1.18 5.07 3.28 Example 20 2.2 2.06 0.96 0.92 6.36 4.17 Example 21 2.4 2.27 1.34 1.31 5.42 2.24 Example 22 2.21 2.09 1.18 1.15 5.43 2.54 Example 23 2.5 1.98 1.35 1.2 20.8 11.11 Example 24 2.64 2 1.18 1.08 24.24 8.47 55 Comparative example 2.278 1.25 1.83 0.97 45.13 46.99 Example 1 1.86 0.58 0.71 0.3 68.82 57.75 Example 2 2.13 1.23 0.51 0.43 42.25 15.69 Example 3 1.98 0.89 0.7 0.22 55.05 68.57 Example 4 2.02 0.66 0.64 0.2 67.33 68.75 Example 5 2.11 0.6 1.33 0.33 71.56 75.19 Example 6 2.07 0.54 1.25 0.21 73.91 83.2 Example 7 1.96 1.17 0.71 0.42 40.31 40.85 Example 8 2.1 1.31 1.2 0.82 37.62 31.67 Example 9 1.95 1.22 0.96 0.47 37.44 51.04 Example 10 2.02 1.21 1.18 0.59 40.1 50 Example 11 2.22 0.59 1.21 0.4 73.42 66.94 Example 12 2.02 0.49 1.22 0.46 75.74 62.3 Example 13 1.99 0.87 0.99 0.3 56.28 69.7 Example 14 2.13 0.68 0.75 0.18 68.08 76 Example 15 1.98 0.99 1.23 0.28 50 77.24 Example 16 2.02 0.79 0.99 0.29 60.89 70.71 Example 17 1.88 0.58 1.31 0.41 69.15 68.7 Example 18 2.13 0.47 1.32 0.36 77.93 72.73 Example 19 1.88 1.16 1.21 0.48 38.3 60.33 Example 20 2.16 1.11 1.12 0.42 48.61 62.5 Example 21 1.99 1.16 1.34 0.42 41.71 68.66 Example 22 2.03 1.03 1.5 0.52 49.26 65.33 Example 23 2.1 0.68 1.4 0.43 67.62 69.29 Example 24 1.9 0.49 1.39 0.38 74.21 72.66 75 Comparative example 2.74 1.15 1.27 0.16 58.03 87.4 Example 1 2.47 1.08 1.35 0.64 56.28 52.59 Example 2 2.07 0.58 One 0.13 71.98 87 Example 3 2.27 1.05 0.77 0.49 53.74 36.36 Example 4 2.03 0 0.52 0.08 100 84.23 Example 5 2.11 0.4 1.33 0.2 81.04 84.96 Example 6 2.22 0.25 1.42 0.33 88.74 76.76 Example 7 2.37 0.66 1.35 0.62 72.15 54.07 Example 8 2.07 0.53 One 0.33 74.4 67 Example 9 2.17 0.8 1.22 0.58 63.13 52.46 Example 10 2.08 0.25 1.42 0.22 87.98 84.51 Example 11 1.98 0.33 1.66 0.34 83.33 79.52 Example 12 1.78 0.15 1.53 0.18 91.57 88.24 Example 13 2 0.23 1.38 0.04 88.5 97.1 Example 14 2.02 0 0.99 0 100 100 Example 15 2.12 0.38 1.37 0.21 82.08 84.67 Example 16 2.03 0.01 1.12 0.02 99.51 98.21 Example 17 1.99 0.18 1.45 0.06 90.95 95.86 Example 18 2.05 0.21 1.38 0.02 89.76 98.55 Example 19 2.43 0.3 1.35 0.23 87.65 82.96 Example 20 2.08 0.04 1.21 0.15 98.08 87.6 Example 21 2.27 0.28 0.88 0.21 87.67 76.14 Example 22 2.13 0 0.78 0 100 100 Example 23 2.28 0.25 1.33 0.02 89.04 98.5 Example 24 2.41 0.19 1.32 0.08 92.12 93.94

<Physical property evaluation: Mechanical properties of self-healing coating material>

When a coating film was made by mixing a compatible resin and a thermoreversible crosslinking agent that contains a hindered urea bond in the molecular structure using nanoindentation, we tried to evaluate the physical properties of the self-healing coating material. When a normal force of 10 mN was applied, changes in indentation hardness and indentation modulus values according to the film were observed, and the results are shown in FIG. 3. In the embodiment, the excellent self-healing phenomenon can be seen in FIG. 2, and the indentation strength as a result of the nanoindentation analysis in FIG. 3 was also improved compared to the commercial product. In addition, it was confirmed that in both Examples 1-24, indentation modulus was maintained similar to that of commercial products.

<Physical property evaluation: Evaluation of endurance and solubility of self-healing coating material>

Self-healing coating materials are not commercialized due to low mechanical properties and expensive development costs. In order to overcome this, a thermoreversible crosslinking agent including a hindered urea bond in the molecular structure was introduced, and examples of endurance and solubility evaluation were shown in Tables 4 and 5 below to evaluate the suitability of the material. In the case of the solvent resistance evaluation, a cotton cloth covered with xylene was covered on the painted surface, and the surface was scratched using a spatula for 5 times at 1-minute intervals, and Examples 1-24 were all excellent. I showed my sex For solubility evaluation, 60 wt% of toluene, PGMEA (Propyene glycol monomethyl ether acetate), EGBE (Ethylene glycol butyl ether), and MEK (methyl ethyl ketone), which are commonly used solvents in Examples 1 to 24, were mixed Then, a solubility test was performed, and Examples 1-4 and 13-16 were found to have the best solubility.

Solvent resistance evaluation Comparative example Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 ◎ ◎ ◎ ○ ○ ○ ○ Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 ◎ ◎ ◎ ○ ○ ○ ○ Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Example 20 ○ ○ ○ ○ ○ ◎ ◎ Example 21 Example 22 Example 23 Example 24 ◎ ○ ○ ○

Solubility evaluation Sample name Toluene PGMEA EGBE MEK Comparative example ◎ ◎ △ ○ Example 1 ◎ ◎ ◎ ○ Example 2 ◎ ◎ ◎ ◎ Example 3 ◎ ◎ ◎ ◎ Example 4 ◎ ◎ ◎ ○ Example 5 ○ ○ ○ ○ Example 6 ○ ○ ○ ○ Example 7 ○ ○ ○ ○ Example 8 ○ ○ ○ ○ Example 9 ○ ○ ○ ○ Example 10 ○ ○ ○ ○ Example 11 ○ ○ ○ ○ Example 12 ○ ○ ○ ○ Example 13 ◎ ◎ ◎ ◎ Example 14 ◎ ◎ ◎ ◎ Example 15 ◎ ◎ ◎ ◎ Example 16 ◎ ◎ ◎ ◎ Example 17 ○ ○ ○ ○ Example 18 ○ ○ ○ ○ Example 19 ○ ○ ○ ○ Example 20 ○ ○ ○ ○ Example 21 ○ ○ ○ ○ Example 22 ○ ○ ○ ○ Example 23 ○ ○ ○ ○ Example 24 ○ ○ ○ ○

Claims (10)

A polymer resin containing a hydroxyl group at the end of the side chain;
A polyfunctional isocyanate containing two or more hindered urea structures in the molecular structure and containing two or more isocyanate groups at the terminal and H-(O-CH ₂ -CH ₂ )n-OH (n is 1 to 10 A thermoreversible polyfunctional additive having a plurality of -OH groups at the ends of the molecular structure produced by reaction with a compound having a chemical structure of integer); And
A self-healing resin composition comprising a polyfunctional isocyanate curing agent and capable of forming a thermoreversible network. The method according to claim 1,
The polymer resin is a self-healing resin composition, characterized in that it has a chemical structure represented by the following formula (1):
<Formula 1>

In Formula 1, m is 0 to 1,000, n is 1 to 1,000, o is an integer of 0 to 100, p is an integer of 0 to 100, q is an integer of 0 to 100, and r is 0 to 100 Is an integer of, s is an integer of 0 to 100, but o and r are not 0 at the same time. The method according to claim 1,
The hindered urea structure is a self-healing resin composition, characterized in that the amine group of the hindered diamine and the isocyanate group of the polyfunctional isocyanate are formed by a urea formation reaction through a 1:2 equivalent reaction. The method according to claim 3,
The hindered diamine is N,N'-di-tertbutylethylenediamine (N,N'-di-tertbutylethylenediamine) or bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate), characterized in that any one of the self-healing resin composition. The method according to claim 3,
The polyfunctional isocyanate is any one of aliphatic, aromatic, alicyclic, or aromatic aliphatic compounds, wherein the self-healing resin composition comprises two or more isocyanate groups in its molecular structure. The method according to claim 3,
The polyfunctional isocyanate is a self-healing resin composition, characterized in that any one of hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI). The method according to claim 1,
The polyfunctional isocyanate is a self-healing resin composition, characterized in that it has a structure of the following formula A1 to formula D1.
<Formula A1>

<Formula B1>

<Formula C1>

<Formula D1>

The method according to claim 1,
The thermoreversible multifunctional additive is a self-healing resin composition, characterized in that it has a structure of the following formula A2 to formula D2:
<Formula A2>

<Formula B2>

<Formula C2>

<Formula D2>

In Formulas A2 to D2, n is an integer of 1 to 10. A clear coat having a scratch self-healing function, which is formed by a crosslinking reaction of the self-healing resin composition according to any one of claims 1 to 8. Preparing a multifunctional isocyanate containing two or more hindered urea structures in the molecular structure and containing two or more isocyanate groups at the terminal;
Thermoreversible polyfunctionality having a plurality of -OH groups at the ends of the molecular structure by reaction of the polyfunctional isocyanate with H-(O-CH ₂ -CH ₂ )n-OH (n is an integer of 1 to 10) as a chain extender Preparing an additive; And
A method for producing a self-healing resin composition, characterized in that it is possible to form a thermoreversible network, including the step of preparing a coating composition of mixing the thermoreversible multifunctional additive, a polymer resin containing a hydroxyl group at the end of the side chain, and a polyfunctional isocyanate curing agent.

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