KR102216613B1 - A sealer composition for reinforcement of steal plate having excellent vibration and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a sealer composition for reinforcing steel sheets having improved vibration damping performance, and a sealer composition for reinforcing steel sheets having excellent vibration damping properties, stiffness, and adhesion even if an asphalt sheet or water-based spray-type damping agent is excluded. It is characterized by providing a method for preparing the composition.

Description

A sealer composition for reinforcing steel plates with excellent vibration damping properties, and a method of manufacturing the same {A SEALER COMPOSITION FOR REINFORCEMENT OF STEAL PLATE HAVING EXCELLENT VIBRATION AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a sealer composition for reinforcing steel sheets having improved vibration damping performance.

The conventional sealer composition for reinforcing a steel sheet is mainly composed of an epoxy resin, and is composed of a filler, a moisture absorbing material, a thickener, a reactive diluent, a curing agent, and a curing accelerator. The sealer composition for reinforcing a steel sheet has an advantage in that it is possible to increase rigidity through an increase in the amount of epoxy and a curing agent. However, there is a problem that there is a curing shrinkage phenomenon after thermal curing, the outer plate deformation of the steel plate occurs at room temperature/low temperature, and the adhesion performance is deteriorated. In addition, due to the lack of vibration suppression performance, there is a problem that vibration occurs in the door and the hood, which are vulnerable parts of the vehicle when driving.

In the prior art, rigidity reinforcement is performed as described above, but due to the problem that the outer plate of the steel plate is deformed after heat hardening and the vibration suppression performance is poor, there is a limitation that the sealer composition for steel plate reinforcement should be applied to only a small part of the automobile body.

In addition, in the prior art, an asphalt sheet and a water-based spray-type vibration damping material are used to impart vibration damping performance, but this is not intended to reinforce the steel plate and only impart vibration damping performance, so the vibration damping material is also a part of the automobile body. It can only be applied to areas such as dash panels or floors, but it is difficult to apply to areas requiring high impact resistance (eg, doors of automobiles), although there is a lot of vibration. In addition, in the case of the asphalt sheet, it was difficult to reduce the weight of the vehicle due to its high specific gravity, and a disadvantage was found that adhesion was poor on the curved surface.In the case of the water-based spray type vibration damper, it was easily dried naturally at room temperature, and the impact resistance was weak. It has also been found that it is difficult to apply to the vulnerable parts of automobiles.

Korean Patent Registration No. 10-0510577 relates to a composition for manufacturing a vibration damping (vibration isolating) sheet attached to an automobile panel to control vibration. Compared to the asphalt-based or butadiene-based composition used for the purpose of controlling vibration damping, it has excellent vibration and vibration damping properties even at a certain high temperature, which is elevated during driving of a vehicle.However, in that it provides a blown asphalt as a damping agent, the conventional It has not completely solved the above problems.

Due to the complex problems of the prior art as described above, there is a need for an integrated product capable of simultaneously imparting stiffness reinforcement and vibration damping performance without causing deformation of the outer plate of the steel plate.

Korean Patent Registration No. 10-0510577

Basically, it has excellent impact resistance to outer plate deformation of the steel plate, and can provide excellent vibration damping performance even if asphalt sheet or water-based spray type damping agent is excluded, as well as the door, roof, floor and side quarters of transport equipment, as well as robot members and houses. It aims to provide a sealer composition that can be used in various fields such as building materials and metal cases.

The object of the present invention is not limited to the object mentioned above. The object of the present invention will become more apparent from the following description, and will be realized by the means described in the claims and combinations thereof.

According to the present invention comprises an epoxy resin mixture, a diluent and a blowing agent,

The epoxy resin mixture provides a sealer composition for reinforcing a steel sheet, comprising an epoxy resin having a viscosity of 15,000 to 35,000 cps and an epoxy equivalent of 250 to 500 g/eq.

The epoxy resin may be an epoxy-polyester hybrid resin.

The epoxy resin mixture may be one selected from the group consisting of rubber-modified epoxy resins, bisphenol A epoxy resins, and combinations thereof.

Including 53% to 77% by weight of the epoxy-polyester hybrid resin, 20% to 33% by weight of the rubber-modified epoxy resin, and 3% to 13% by weight of the bisphenol A epoxy resin based on the epoxy resin mixture can do.

The rubber-modified epoxy resin may have an epoxy equivalent of 245 to 465 g/eq.

The rubber-modified epoxy resin is an acrylic rubber modified epoxy resin, a nitrile-butadiene rubber (NBR) modified epoxy resin, a carboxyl terminated butadiene acrylonitrile (CTBN) modified epoxy resin, and these It may be one selected from the group consisting of a combination of.

The bisphenol A type epoxy resin may have an epoxy equivalent of 184 to 190 g/eq.

The diluent may include an epoxide group.

The diluent may have an epoxy equivalent of 300 to 330g/eq.

The diluent may be one selected from the group consisting of a monofunctional aliphatic glycidyl ether, a bifunctional aliphatic glycidyl ether, an aromatic glycidyl ether, and combinations thereof.

The blowing agent may be one selected from the group consisting of a chemical blowing agent, a physical blowing agent, and a combination thereof.

The chemical blowing agent is one selected from the group consisting of azodicarbonamide, hydrazine derivatives, semicarbazide, tetrazole, and combinations thereof, and the physical blowing agent is acrylonitrile. , It may be one selected from the group consisting of acrylic compounds and combinations thereof.

According to the present invention, 20 to 40% by weight of an epoxy-polyester hybrid resin, 5 to 25% by weight of a rubber-modified epoxy resin, 1 to 10% by weight of a bisphenol A type epoxy resin, 10 to 30% by weight of a diluent, 0.3 to 3% by weight of a blowing agent % And 21.8 to 56% by weight of the additive, and the additive is one selected from the group consisting of a curing agent, a curing accelerator, a filler, a conductivity imparting agent, and a combination thereof. .

The epoxy-polyester resin can be prepared by adding a fatty acid to a general-purpose epoxy resin.

The fatty acid may be one selected from the group consisting of linear dimer fatty acids, cyclic fatty acids, aromatic fatty acids, and combinations thereof.

The rubber-modified epoxy resin can be modified with one selected from the group consisting of acrylic rubber, nitrile-butadiene rubber, carboxyl terminated butadiene acrylonitrile, and combinations thereof. I can.

According to the present invention, 20 to 40% by weight of an epoxy-polyester hybrid resin, 5 to 25% by weight of a rubber-modified epoxy resin, 1 to 10% by weight of a bisphenol A type epoxy resin, 10 to 30% by weight of a diluent, 0.5 to 3% by weight of a foaming agent %, 1 to 3% by weight of a curing agent, 0.5 to 2% by weight of a curing accelerator, 20 to 50% by weight of a filler, and 0.3 to 1% by weight of a conductivity imparting agent can be provided. have.

The use of the sealer composition according to the present invention has the effect of improving the rigidity of the steel sheet.

If the sealer composition according to the present invention is used, it is possible to solve the problem that the outer plate of the steel plate is deformed or the adhesion performance is poor after heat curing.

When the sealer composition according to the present invention is used, excellent vibration suppression performance can be obtained.

When the sealer composition according to the present invention is used, it is possible to reduce the vibration phenomenon that occurs when driving a vehicle.

The effects of the present invention are not limited to the effects mentioned above. It should be understood that the effects of the present invention include all effects that can be inferred from the following description.

The above objects, other objects, features, and advantages of the present invention will be easily understood through the following preferred embodiments related to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed contents may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

In describing each drawing, similar reference numerals have been used for similar elements. In the accompanying drawings, the dimensions of the structures are shown to be enlarged than actual for clarity of the present invention. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present specification, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of being added. Further, when a part such as a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where the other part is "directly above" but also the case where there is another part in the middle. Conversely, when a part such as a layer, a film, a region, or a plate is said to be "under" another part, this includes not only the case where the other part is "directly below", but also the case where there is another part in the middle.

Unless otherwise specified, all numbers, values, and/or expressions expressing quantities of ingredients, reaction conditions, polymer compositions, and formulations used herein are those that occur in obtaining these values, among other things essentially. Since they are approximations that reflect the various uncertainties of the measurement, it should be understood as being modified in all cases by the term "about". In addition, when numerical ranges are disclosed herein, these ranges are continuous and, unless otherwise indicated, include all values from the minimum value of this range to the maximum value including the maximum value. Furthermore, when this range refers to an integer, all integers from the minimum value to the maximum value including the maximum value are included, unless otherwise indicated.

In the present specification, when a range is described for a variable, it will be understood that the variable includes all values within the stated range, including the stated endpoints of the range. For example, a range of "5 to 10" includes values of 5, 6, 7, 8, 9, and 10, as well as any subranges such as 6 to 10, 7 to 10, 6 to 9, 7 to 9, etc. Inclusive, and it will be understood to include any values between integers that are reasonable in the scope of the stated range, such as 5.5, 6.5, 7.5, 5.5 to 8.5 and 6.5 to 9, and the like. Also, for example, the range of "10% to 30%" is 10% to 15%, 12% to 10%, 11%, 12%, 13%, etc., as well as all integers including up to 30%. It will be understood to include any subranges such as 18%, 20% to 30%, and the like, and include any values between reasonable integers within the scope of the stated range, such as 10.5%, 15.5%, 25.5%, and the like.

The sealer composition for reinforcing steel sheet of the present invention comprises an epoxy resin mixture, a diluent and a foaming agent, and the epoxy resin mixture comprises an epoxy resin having a viscosity of 15,000 to 35,000 cps and an epoxy equivalent of 250 to 500 g/eq.

The epoxy resin is an epoxy-polyester hybrid resin.

The epoxy-polyester hybrid resin contains 53% to 77% by weight based on the epoxy resin mixture. At this time, if it is less than 53% by weight, adhesion and cohesion with the steel plate may be reduced, and if it is more than 77% by weight, there is a problem that the outer plate deformation and peeling of the steel plate occur.

The epoxy-polyester hybrid resin is obtained by reacting a dicarboxylic acid prepared through an oligomerization process of an unsaturated fatty acid with an epoxy resin, and has the rigidity of the epoxy and the flexibility of the polyester.

The epoxy-polyester hybrid resin is characterized by adding a fatty acid to the epoxy section. The fatty acid is one selected from the group consisting of linear dimer fatty acids, cyclic fatty acids, aromatic fatty acids, and combinations thereof. The linear dimer acid serves to increase the flexibility, and the cyclic fatty acid and the aromatic fatty acid make the epoxy-polyester hybrid resin into a polymer resin having a mesh structure to prevent the formation of bubbles due to the deposition of low molecular moisture. .

The epoxy-polyester hybrid resin has a viscosity of 15,000 to 35,000 cps and an epoxy equivalent of 250 to 500 g/eq.

The epoxy resin mixture may further include one selected from the group consisting of rubber-modified epoxy resins, bisphenol A epoxy resins, and combinations thereof.

The rubber-modified epoxy resin is contained in an amount of 20% to 33% by weight based on the epoxy resin mixture. At this time, if it is less than 20% by weight, a low-temperature impact problem may occur, and if it exceeds 33% by weight, a problem of insufficient strength occurs.

The rubber-modified epoxy resin is an acrylic rubber modified epoxy resin, a nitrile-butadiene rubber (NBR) modified epoxy resin, a carboxyl terminated butadiene acrylonitrile (CTBN) modified epoxy resin, and these It may be one selected from the group consisting of a combination of.

The rubber-modified epoxy resin is characterized in that the epoxy equivalent is 245 to 465g/eq.

The bisphenol A-type epoxy resin contains 3% by weight to 13% by weight based on the epoxy resin mixture. At this time, if it is less than 3% by weight, strength decrease and uncured phenomenon may occur, and if it exceeds 13% by weight, there is a problem that vibration damping property decreases and steel sheet peeling occurs.

The bisphenol A-type epoxy resin is characterized in that the epoxy equivalent is 184 to 190g/eq.

The viscosity of the bisphenol A type epoxy resin may be 11,500 to 13,500 cps at room temperature.

According to the present invention, the sealer composition for reinforcing steel sheet is characterized in that it further comprises one additive selected from the group consisting of a curing agent, a curing accelerator, a filler, a conductivity imparting agent, and a combination thereof in addition to an epoxy resin mixture, a diluent and a foaming agent.

Preferably, the sealer composition for reinforcing a steel sheet of the present invention includes an epoxy-polyester hybrid resin, a rubber-modified epoxy resin, a bisphenol A type epoxy resin, a diluent, a foaming agent, and an additive.

At this time, the content of each component is 20 to 40% by weight of epoxy-polyester hybrid resin, 5 to 25% by weight of rubber-modified epoxy resin, 1 to 10% by weight of bisphenol A type epoxy resin, 10 to 30% by weight of diluent, 0.3 to 3 foaming agents. 21.8 to 56% by weight and additives. At this time, the additive may be one selected from the group consisting of a curing agent, a curing accelerator, a filler, a conductivity imparting agent, and a combination thereof.

Preferably, the sealer composition for reinforcing a steel sheet of the present invention includes an epoxy-polyester hybrid resin, a rubber-modified epoxy resin, a bisphenol A type epoxy resin, a diluent, a foaming agent, a curing agent, a curing accelerator, a filler, and a conductivity imparting agent.

At this time, the content of each component is 20 to 40% by weight of epoxy-polyester hybrid resin, 5 to 25% by weight of rubber-modified epoxy resin, 1 to 10% by weight of bisphenol A epoxy resin, 10 to 30% by weight of diluent, 0.5 to 3 of foaming agent It is characterized in that it contains 1 to 3% by weight of a curing agent, 0.5 to 2% by weight of a curing accelerator, 20 to 50% by weight of a filler, and 0.3 to 1% by weight of a conductivity imparting agent.

In the case of the diluent, when less than 10% by weight, shrinkage of the steel sheet and a decrease in vibration damping property may occur, and when it exceeds 30% by weight, decrease in adhesion and strength may occur.

In the case of the foaming agent, when less than 0.5% by weight, the foaming rate decreases and the steel sheet shrinks, and when it exceeds 3% by weight, the strength decrease problem due to the increase in the foaming rate may occur.

In the case of the curing agent, when less than 1% by weight, uncuring occurs even at high temperatures, and when it exceeds 3% by weight, a problem of shrinkage of the steel sheet may occur due to excessive exothermic reactions.

In the case of the curing accelerator, when less than 0.5% by weight, the curing agent is insufficient, resulting in a problem of uncuring, and when it exceeds 2% by weight, the problem of steel sheet deformation may occur due to excessive exothermic reaction.

In the case of the filler, when less than 20% by weight, vibration damping performance, adhesive strength, and flexural strength are lowered, and when it exceeds 50% by weight, the strength is too high, causing a problem in impact resistance, and peeling may occur.

When the conductivity imparting agent is less than 0.3% by weight, the foaming rate may decrease and the steel sheet shrinkage may occur, and when it exceeds 3% by weight, the strength decrease problem due to the increase in the foaming rate may occur.

The diluent is used for the purpose of imparting flexibility or viscosity to the epoxy resin, and the diluent may include an epoxide group. Specifically, it is preferably one selected from the group consisting of a monofunctional aliphatic glycidyl ether, a bifunctional aliphatic glycidyl ether, an aromatic glycidyl ether, and combinations thereof. More preferably, the number average molecular weight of the diluent is 300 to 600 bifunctional aliphatic glycidyl ether.

The epoxy equivalent of the diluent may be 300 to 330g/eq.

The viscosity of the diluent may be 40 to 100 cps at room temperature.

The blowing agent may be one selected from the group consisting of a chemical blowing agent, a physical blowing agent, and a combination thereof.

The chemical blowing agent is one selected from the group consisting of azodicarbonamide, hydrazine derivatives, semicarbazide, tetrazole, and combinations thereof. It is preferably an azodicarbonamide having an average particle size of 5.7 to 6.1 µm and a gas generation amount of 220 to 240 ml/g.

The physical foaming agent may be an expandable foaming agent enclosing a low boiling point solvent with a polymer membrane to form a fine and constant closed cell, and specifically, may be one selected from the group consisting of acrylonitrile, acrylic compounds, and combinations thereof.

When the chemical foaming agent and the physical foaming agent are mixed and used, gas is generated during the curing process, thereby maintaining the shape after curing, preventing a strong dent phenomenon, and supplementing the vibration of the steel plate while driving a vehicle.

The curing agent may be used for the purpose of curing during the painting process.

The curing accelerator may be used together with the curing agent to control and accelerate the reaction according to changes in temperature and curing time.

The conductivity imparting agent is used for the purpose of inducing electrical conductivity, and may be one selected from the group consisting of carbon black, PAN-based carbon fiber, metal powder, metal fiber, metal flakes, zinc oxide, and combinations thereof.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are only examples to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example 1 and Comparative Examples 1 to 5

The sealer compositions of Example 1 and Comparative Examples 1 to 5 were prepared according to the component ratios shown in Table 1 below.

Classification (% by weight) Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Epoxy-polyester ¹⁾ 25 30 30 25 25 25 Rubber modified epoxy resin ²⁾ 5 - 5 10 5 5 Bisphenol A type resin ³⁾ 5 5 - 15 5 5 Diluent ⁴⁾ 15 15 15 15 15 Hardener ⁵⁾ 2 2 2 2 2 2 Hardening accelerator ⁶⁾ 0.5 0.5 0.5 0.5 0.5 0.5 Filler Mica 28.8 28.8 28.8 28.8 28.8 28.8 Talc 5 5 5 5 5 5 Calcium carbonate 10 10 10 10 10 10 blowing agent Chemical blowing agent ^7-1) 2 2 2 2 - 3.5 Physical blowing agent ^7-2) 1.5 1.5 1.5 1.5 3.5 - Conductivity imparting agent ⁸⁾ 0.2 0.2 0.2 0.2 0.2 0.2 Sum 100 100 100 100 100 100 1) Epoxy-polyester: TER-M305, Taeiltech
2) Rubber modified epoxy resin: DER-301, Dow chemical
3) Bisphenol Type A resin: YD-128, Kukdo Chemical
4) Reactive diluent: PG-207P, Kukdo Chemical
5) Hardener: DDA-5, CVC
6) Hardening accelerator: UR-700, Alz chem
7-1) Chemical blowing agent: AC-7000, Geumyang
7-2) Physical blowing agent: F-102D, Matsumoto Yushi-Shiyaku
8) Conductivity imparting agent: A-black, Denka

Experimental Example 1 (Physical property evaluation)

After applying the sealer composition prepared in Example 1 and Comparative Examples 1 to 5 to a steel sheet, the results of measuring the physical properties of the specimen obtained by curing each composition under the curing conditions (electrodeposition, medium/top coat) of each factory are shown below. It is shown in Table 2.

division Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Adhesive strength (0.5㎜, ㎏/㎠) 182 170 135 154 168 112 Flexural strength (1.5t, kgf) 5.8 5.6 5.5 6.5 6.1 5.2 Volume change rate (%) 78 81 91 73 65 103 Low temperature impact (times) 30 times or more 30 times or more 30 times or more 20 or more 30 times or more 30 times or more Flow
(Mm) Room temperature, 4 hours 0 One One 4 0 0 180℃, 20 minutes 0 2 2 10 0 0

Looking at the results of Table 2, it can be seen that the present invention (Example 1) has excellent physical properties compared to Comparative Examples 1 to 5.

Experimental Example 2 (evaluation of cold resistance flexural property)

After applying the sealer composition prepared in Example 1 and Comparative Examples 1 to 5 at 150x80x1.5mm on a steel plate (300x300mm), cured under the curing conditions (electrodeposition, medium/top coat) of each factory, and then left for 6 hours or more I did. After that, it was left to stand for -30°C/30 minutes, and then the iron plate was placed on a horizontal surface in an atmosphere of -30°C, and the height difference between the horizontal surface and the iron plate was measured, and the results are shown in Table 3 below.

Test Items Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Cold resistance
(Mm) 1.2 2.5 1.5 2.2 1.7 2.5

According to the results of Table 3, it can be seen that the present invention (Example 1) has better physical properties compared to Comparative Examples 1 to 5.

Experimental Example 3 (evaluation of vibration damping property)

After applying the sealer composition prepared in Example 1 and Comparative Examples 1 to 5 on a steel sheet, each composition was sequentially cured at 180°C for 20 minutes and 150°C for 20 minutes (twice) to obtain a specimen.

The measurements of the vibration suppression coefficient for the result are shown in Table 4 below. The vibration damping coefficient was measured in accordance with KS D 0076 (Test method for vibration damping characteristics of vibration damping steel plate).

Test Items Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Damping factor 0.183 0.171 0.156 0.12 0.166 0.154

According to the results of Table 4, it can be seen that the present invention (Example 1) exhibits better vibration damping performance compared to Comparative Examples 1 to 5.

Claims (17)

Epoxy-polyester hybrid resin 20 to 40% by weight, rubber modified epoxy resin 5 to 25% by weight, bisphenol A type epoxy resin 1 to 10% by weight, diluent 10 to 30% by weight, foaming agent 0.3 to 3% by weight, and additives 21.8 to Including 56% by weight,
The additive includes one selected from the group consisting of a curing agent, a curing accelerator, a filler, a conductivity imparting agent, and combinations thereof,
The epoxy-polyester hybrid resin has a viscosity of 15,000 to 35,000 cps and an epoxy equivalent of 250 to 500 g/eq. delete delete delete The method of claim 1,
The rubber-modified epoxy resin is a sealer composition for reinforcing steel sheet, characterized in that the epoxy equivalent of 245 to 465g / eq. The method of claim 1,
The rubber-modified epoxy resin is an acrylic rubber modified epoxy resin, a nitrile-butadiene rubber (NBR) modified epoxy resin, a carboxyl terminated butadiene acrylonitrile (CTBN) modified epoxy resin, and these Sealer composition for reinforcing steel sheet, characterized in that one selected from the group consisting of a combination of. The method of claim 1,
The bisphenol A-type epoxy resin is a sealer composition for reinforcing steel sheet, characterized in that the epoxy equivalent of 184 to 190g / eq. The method of claim 1,
The diluent is a sealer composition for reinforcing steel sheet, characterized in that it contains an epoxide group. The method of claim 1,
The diluent is a sealer composition for steel sheet reinforcement, characterized in that the epoxy equivalent of 300 to 330g / eq. The method of claim 1,
The diluent is one selected from the group consisting of monofunctional aliphatic glycidyl ether, difunctional aliphatic glycidyl ether, aromatic glycidyl ether, and combinations thereof. The method of claim 1,
The foaming agent is a sealer composition for reinforcing steel sheet, characterized in that one selected from the group consisting of chemical foaming agents, physical foaming agents, and combinations thereof. The method of claim 11,
The chemical blowing agent is one selected from the group consisting of azodicarbonamide, hydrazine derivatives, semicarbazide, tetrazole, and combinations thereof,
The physical foaming agent is one selected from the group consisting of acrylonitrile, acrylic compounds, and combinations thereof. Epoxy-polyester hybrid resin 20 to 40% by weight, rubber modified epoxy resin 5 to 25% by weight, bisphenol A type epoxy resin 1 to 10% by weight, diluent 10 to 30% by weight, foaming agent 0.3 to 3% by weight and additives 21.8 to Including 56% by weight,
The additive is one selected from the group consisting of a curing agent, a curing accelerator, a filler, a conductivity imparting agent, and a combination thereof. The method of claim 13,
The epoxy-polyester hybrid resin is a method for producing a sealer composition for reinforcing steel sheet, characterized in that it is prepared by adding a fatty acid to an epoxy resin. The method of claim 14,
The fatty acid is one selected from the group consisting of linear dimer fatty acids, cyclic fatty acids, aromatic fatty acids, and combinations thereof. Method for producing a sealer composition for reinforcing steel sheet The method of claim 13,
The rubber-modified epoxy resin is an epoxy resin modified with one selected from the group consisting of acrylic rubber, nitrile-butadiene rubber, carboxyl terminated butadiene acrylonitrile, and combinations thereof. Method for producing a sealer composition for reinforcing steel sheets, characterized in that. Epoxy-polyester hybrid resin 20 to 40% by weight, rubber modified epoxy resin 5 to 25% by weight, bisphenol A type epoxy resin 1 to 10% by weight, diluent 10 to 30% by weight, foaming agent 0.5 to 3% by weight, curing agent 1 to 3% by weight, 0.5 to 2% by weight of a hardening accelerator, 20 to 50% by weight of a filler, and 0.3 to 1% by weight of a conductivity imparting agent.