KR101357299B1 - Sealer composition having double layer for reinforcing the steel plate - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealer composition for reinforcing steel sheet, comprising a double structure steel sheet reinforcing sealer composition applied to automobile doors, hoods, side shells, and inner portions, and including a lower layer sealer for shrinkage absorption and an upper layer for rigid reinforcement. Provided is a sealer composition for reinforcing steel sheet having a two-layer structure including a sealer.
When the sealer composition having a two-layer structure according to the present invention is applied to a steel sheet by applying NBR rubber, a chemical crosslinking agent to a lower layer structure, and applying a tetrafunctional epoxy resin, a trifunctional epoxy resin, a modified epoxy resin, etc. to an upper layer structure. It is suitable to be applied to automotive sealer because it can show the effect of reinforcing steel plate stiffness, improving shrinkage at room temperature and low temperature, and improving adhesion to steel plate.

Description

Sealer composition having double layer for reinforcing the steel plate}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealer composition for reinforcing steel sheet, comprising a double structure steel sheet reinforcing sealer composition applied to automobile doors, hoods, side shells, and inner portions, and including a sealer of a lower layer for shrinkage absorption and an upper layer for rigid reinforcement. It relates to a steel sheet reinforcement sealer composition having a two-layer structure including a sealer.

Recently, steel sheet reinforcement sealers used in automobiles are applied directly to areas where stiffness is weak to maintain rigidity. However, the conventional steel reinforcement sealer has a problem that deformation of the outer shell of the car occurs at room temperature and low temperature, and when the cryogenic shock is affected, the separation from the panel. In addition, there is a problem that the running noise occurs when driving the vehicle due to the lack of vibration damping. Existing steel reinforcement sealer can increase the rigidity by increasing the amount of hardening agent and hardening accelerator, but there is a serious problem of deformation of the outer plate at room temperature / low temperature after hardening. .

In order to improve the problems of the conventional automotive sealer, a steel sheet reinforcement sealer composition having a two-layer structure has been developed. That is, in Korean Patent Laid-Open Publication No. 2009-0099362, the sealer composition (lower plate) applied to the steel sheet contains rubber to enhance the flexibility and elastic modulus of the sealer, and the upper portion of the lower plate (upper plate) maintains the rigidity and damping of the steel plate and A composition has been proposed to improve dust resistance.

Such a two-layered steel sheet reinforcement sealer composition is superior in rigidity and low-temperature shrinkage than conventional one-layered steel sheet reinforcement, but there is still a problem in room temperature and low temperature deformation, vibration damping performance quality due to limitations in the low temperature characteristics of the epoxy resin.

In addition, SBR rubber and EPDM rubber used in the lower layer of the two-layer structure as the main component has a low elongation at the time of hardening and artificially makes the sealer as a foam type by using a physical foaming agent, so the elongation and strength is low. When the strength increased, shrinkage occurred at room temperature and low temperature, and adhesion problems with the steel sheet occurred after curing. Therefore, further research was needed to remedy this problem.

Therefore, the inventors of the present invention have tried to solve the problems of the prior art, using the NBR (acrylonitrile-butadiene rubber) rubber and chemical crosslinking agent in the lower sealer adhesion problems due to elongation prevention and shrinkage problems due to strength increase The present invention was completed by discovering that problems such as strength reduction, room temperature and low temperature shrinkage, dust removal, and the like can be simultaneously solved by using a tetrafunctional and trifunctional epoxy resin for the upper sealer.

Accordingly, it is an object of the present invention to provide a sealant composition for reinforcing steel sheet which is excellent in strengthening adhesion with the steel sheet, reducing shrinkage at room temperature and low temperature, and excellent vibration damping performance.

The present invention for achieving the above object is a sealer composition having a two-layer structure of a lower sealer and an upper sealer,

The lower layer sealer comprises NBR (acrylonitril-butadiene rubber) rubber, chemical crosslinking agent, conductivity giving agent, curing agent, filler, thermal aging inhibitor, hygroscopic agent and plasticizer;

The upper sealer is characterized in that it comprises a tetrafunctional epoxy resin, trifunctional epoxy resin, BPA (bisphenol-A) epoxy resin, rubber modified epoxy resin, polyester, curing agent, filler, anti-separation agent, moisture absorbent, colorant and stabilizer Provided is a sealer composition for reinforcing steel sheet having a two-layer structure.

When the sealer composition having a two-layer structure according to the present invention is applied to a steel sheet by applying NBR rubber, a chemical crosslinking agent to a lower layer structure, and applying a tetrafunctional epoxy resin, a trifunctional epoxy resin, a modified epoxy resin, etc. to an upper layer structure. It is suitable to be applied to automotive sealer because it can show the effect of reinforcing steel plate stiffness, improving shrinkage at room temperature and low temperature, and improving adhesion to steel plate.

1 is a graph showing the results of MS SPEC standard bending strength test results of Example 1 and Comparative Example 1.
Figure 2 is a graph showing the test results of cold resistance (test specimen) based on the MS SPEC standard of Example 1 and Comparative Example 1.
3 is a graph showing the results of the cold resistance (part) test based on the MS SPEC standard of Example 1 and Comparative Example 1. FIG.
Figure 4 is a graph showing the results of the MS SPEC standard dustproofness (vibration resistance) test of Example 1 and Comparative Example 1.

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

Sealer composition for reinforcing steel sheet according to the present invention,

Lower layer sealers including NBR (acrylonitril-butadiene rubber) rubbers, chemical crosslinkers, conductivity giving agents, hardeners, fillers, anti-aging agents, hygroscopic agents, and plasticizers; And

2 comprising an upper sealer comprising a tetrafunctional epoxy resin, a trifunctional epoxy resin, a bisphenol-A (BPA) epoxy resin, a rubber modified epoxy resin, a polyester, a curing agent, a filler, an antisegregating agent, a hygroscopic agent, a colorant and a stabilizer It is characterized by a layer structure.

The lower layer sealer is 20-40% by weight of NBR rubber, 0.2-1.5% by weight of chemical crosslinking agent, 0.2-1.0% by weight of conductivity imparting agent, 1-3% by weight of curing agent, 10-20% by weight of needle filler, 5-15% by weight filler. %, 15-30 weight% of spherical fillers, 2-5 weight% of hygroscopic agents, 0.1-2 weight% of thermal aging inhibitors, and 20-45 weight% of plasticizers are preferable.

In this case, the lower layer sealer may include an NBR rubber and a chemical crosslinking agent, thereby improving adhesion due to prevention of elongation reduction, and may also improve shrinkage by increasing strength.

In addition, the upper sealer is 0.5 to 3.5% by weight of the tetrafunctional epoxy resin, 0.5 to 3.5% by weight of the trifunctional epoxy resin, 10 to 20% by weight of the BPA (bisphenol-A) epoxy resin, 5 to 15% by weight of the rubber-modified epoxy resin %, 5 to 10 wt% polyester, 1 to 6 wt% curing agent, 5 to 10 wt% needle filler, 15 to 30 wt% bulk filler, 10 to 20 wt% spherical filler, 1 to 3 wt% separation inhibitor, moisture absorbent It is preferable to comprise 1 to 3.5% by weight, 0.3 to 1% by weight of colorant and 1-2% by weight of stabilizer.

The upper sealer can satisfy quality problems such as lowering strength, lowering room temperature and low temperature shrinkage, and lowering vibration damping due to lowering rigidity.

At this time, the ratio of the lower sealer and the upper sealer preferably has a weight ratio of 3: 1 to 1: 3, more preferably 1: 1 to 1: 1.5.

Hereinafter, the sealer composition for reinforcing the dual structure steel sheet of the present invention will be described in detail for each component.

The NBR rubber used in the lower layer composition in the present invention has high elongation and is formed in a non-foaming type, thereby improving room temperature and low temperature shrinkage by strengthening the steel sheet and increasing elongation. At this time, the content of NBR rubber is preferably 20 to 40% by weight in the lower layer sealer. If less than 20% by weight shrinkage occurs due to elongation is lowered, if it exceeds 40% by weight may increase the strength due to the increase in elongation.

The chemical crosslinking agent used in the present invention is used to solve the problem of conventional vulcanizing agents. That is, the vulcanizing agent used in the prior art continuously reacts at room temperature for a long time after the curing reaction, thereby causing problems of strength increase and elongation. In order to solve the above problems by using a chemical crosslinking agent to stop the elongation and strength increase, which is a problem of long-term reaction by the method of completing the reaction at a time, it plays a role in maintaining the elongation and sustain strength. Specific examples of the chemical crosslinking agent used in the present invention include dibenzenothiazyl disulfide (DM), tetramethyl thiuram disulfide (MTTD), dicumyl peroxide, and the like. It is preferable that the usage-amount of the said chemical crosslinking agent is 0.2 to 1.5 weight% in a lower layer sealer. If the amount is less than the amount, there is a problem of uncuring due to the lack of crosslinking, and when more than the amount is used, there is a problem of strength increase due to overcuring and shell bending.

The conductivity providing agent used in the present invention is used to induce electrical conductivity, and specific examples include electroless plating of the surface of carbon black, PAN-based carbon fiber, metal powder, metal fiber, metal flake, mica or glass fiber. It may include one or more selected from the surface of the titanium oxide, antimony-coated tin oxide, calcium carbonate and zinc oxide, but is not necessarily limited thereto. It is preferable that the said electroconductivity imparting agent is used in 0.2-1.0 weight% ratio in a lower layer sealer. If the content is less than 0.2% by weight, a problem arises in that the formation of electrodeposition coating film is insufficient, and when the content is more than 1.0% by weight, bending may occur in the steel sheet.

In the present invention, the curing agent is used for curing in the painting process, it is preferable to use mainly an amide-based curing agent. Specific examples thereof include dicyandiamide. Moreover, it is preferable that the usage-amount of a hardening | curing agent is used in 1 to 3 weight% in a lower layer sealer, and 1 to 6 weight% in an upper sealer. If the amount of the curing agent is too small, uncuring occurs even at high temperatures, and if too large, the shrinkage of the steel sheet may occur due to excessive exothermic reactions.

In the present invention, the filler is used by mixing three kinds of filler. That is, a needle filler, a bulk filler, and a spherical filler are mixed and used. The reason for mixing and using different types of fillers is to improve workability and rigidity and to prevent shrinkage and flow.

Among these, the needle-shaped filler is composed of a needle-like structure to improve the strength deterioration phenomenon due to the weight loss of rubber and to improve the vibration damping performance, and the amount of the needle filler is preferably used at 10 to 20% by weight in the lower sealer. If it is less than 10% by weight, problems of flow and strength may occur due to a decrease in viscosity, and if it is more than 20% by weight, poor product formation and shrinkage may occur due to an increase in viscosity and an increase in strength.

In addition, the bulk filler is used to maintain the shape of the product and maintain the strength, the amount is preferably 5 to 15% by weight in the lower layer sealer. If the amount is less than 5% by weight, the adhesive strength and flexural strength are lowered. If the amount is more than 15% by weight, the strength may be too high.

In addition, the spherical filler is used to maintain the shape of the product and to improve the workability, the amount is preferably 15 to 30% by weight in the lower sealer. If it is less than 15% by weight, there is a problem of reduced discharge due to reduced workability, and if it exceeds 30% by weight, excessive discharge may occur.

As a specific example of the filler, it is preferable to use one or more selected from calcium carbonate, aluminum hydroxide, fatty acid coated filler, silicate and wollastonite, but is not limited thereto.

In the present invention, the thermal aging inhibitor is used for the purpose of preventing thermal aging of the rubber component and it is preferable to use an active ingredient having an alkylate bisphenol structure, but specific erosion is 2,2'-methylene-bis (4- Methyl-6-tert-butylphenol). The amount of heat aging inhibitor is appropriately used in the lower layer sealer in an amount of 0.1 to 2% by weight, and when the amount is less than 0.1% by weight, a problem of shrinkage due to heat occurs, and when it exceeds 2% by weight, the viscosity is low and bubbles are formed inside during curing. May occur.

In the present invention, the plasticizer is used for viscosity control, and preferably a phthalate-based plasticizer is used. The amount of plasticizer used is preferably 20 to 45% by weight based on the lower layer sealer. If the amount is less than 20% by weight, there is a problem of less discharge due to lower workability, and if the amount exceeds 45% by weight, problems such as flow due to viscosity decrease, poor adhesion (peeling), and strength drop may occur.

In addition to the above components, the lower layer sealer of the present invention may further contain 0 to 5% by weight of additives such as a hygroscopic agent and an adhesion agent.

The moisture absorbent is converted to Ca (OH) ₂ through the reaction with moisture when moisture in the air penetrates the sealer, and serves to prevent problems such as air bubbles, sealer peeling off, contamination of the steel sheet, degradation of rigidity, etc. In the lower layer sealer, 0 to 5% by weight, preferably 2 to 5% by weight is appropriate. When the steel sheet is applied by the moisture absorbent, it can solve the problem of bubbles, flow, and strength drop due to the inflow of moisture in the sealer, and when excessively added in excess of 5% by weight, the steel sheet is bent due to heat generation. In addition, sealer cracks may occur. Examples of such absorbents include, but are not limited to, calcium oxide, ash, liquid calcium oxide or quicklime.

The adhesion agent serves to prevent adhesion failure (peeling) occurs by facilitating the adhesion of the steel plate and the sealer, the amount of use is 0 to 5% by weight, preferably 2 to 5% by weight in the lower layer sealer proper.

Examples of such attachment agents include, but are not limited to, urethane modified resins, vinyl chloride resins, acrylic modified resins, or amide resins.

Hereinafter, the component used for an upper sealer other than the said component is demonstrated concretely.

In the present invention, the tetrafunctional epoxy resin and trifunctional epoxy resin reacts with the curing agent in a 1: 1 equivalent, and the existing epoxy resin is a chain structure during the reaction to increase the pulling force to each other, but shrinkage occurs In the case of the tetrafunctional epoxy and the trifunctional epoxy resin, when the reaction with the curing agent has a column structure, the pulling force is reduced to reduce the room temperature shrinkage and improved the vibration damping performance to the column structure. The amount of the tetrafunctional epoxy resin and the amount of the trifunctional epoxy resin are 0.5 to 3.5% by weight with respect to the upper filler, respectively, and the use of less than 0.5% by weight causes room temperature shrinkage. There is a problem that a phenomenon of strength degradation occurs. The tetrafunctional epoxy resin is an aromatic or aliphatic compound having four epoxy functional groups bonded thereto, with no particular limitation on its selection. As the tetrafunctional epoxy resin, specifically, 1,1,2,2-tetrakis (4- (oxirane-2-yloxy) phenyl) ethane represented by the following Chemical Formula 1 may be included.

[Formula 1]

The trifunctional epoxy resin is an aromatic or aliphatic compound having three epoxy functional groups bonded thereto, with no particular limitation on its selection. Such trifunctional epoxy resin may specifically include 2-((2,2-bis (((oxirane-2-yl) methoxy) methyl) butoxy) methyl) oxirane represented by the following formula (2): have.

(2)

In the present invention, the BPA epoxy resin used in the upper layer composition is a main component that gives strength, and its amount is preferably used in an amount of 10 to 20% by weight. When the amount is less than 10% by weight, the strength is insufficient, when the amount exceeds 20% by weight there is a problem that the steel sheet rise and the steel sheet peeling occurs.

The rubber-modified epoxy resin used in the present invention is applied to CTBN (carboxyl terminated butadiene acrylonitrile rubber) modified epoxy having a low volume change rate to improve the strength degradation caused by BPA loss and to apply CTBN (rubber) modified epoxy resin having excellent vibration damping performance. To improve the damping performance. The content of the rubber-modified epoxy resin is 5 to 1.5% by weight, and when the content is less than 5% by weight, a problem occurs in reducing the strength of the steel sheet.

In the present invention, the polyester resin used for improving low temperature shrinkage is an epoxy diluent, which is unreacted with a curing agent, and an epoxy diluent which reduces the shrinkage phenomenon after curing of epoxy. The shrinkage phenomenon is 5 to 10% by weight, and 5% by weight. If less than a problem occurs when the strength of the steel sheet rises and shrinkage occurs, and when more than 10% by weight, the steel sheet strength decreases, the steel sheet peeling, polyester resin leaching (liquid separation) problems occur.

Separation inhibitor used in the present invention is preferably used in the range of 1.0 to 3.0% by weight, it is possible to prevent the separation phenomenon between the upper layer and the lower layer that may occur during curing due to the incompatibility between the rubber of the lower layer and the epoxy resin of the upper layer. Can be. As the separation inhibitor, polybutene may be used.

The stabilizer used in the present invention is used to prevent aging due to heat, and its amount is suitably 1 to 2% by weight in the upper sealer. If the amount of use is less than 1% by weight, a problem of shrinkage due to heat occurs, and if it exceeds 2% by weight, the viscosity may be low and bubbles may be generated during curing. Examples of such stabilizers include, but are not limited to, monoepoxide oil, soybean oil, titanate oil, and the like.

In addition to the above components, the upper sealer of the present invention may be used by a person skilled in the art in the range that does not impair the physical properties of the composition for stiffening reinforcement as an additive commonly used in the art. Such additives may further include low temperature diluents, moisture absorbents, flow inhibitors, colorants, tackifiers, silane coupling agents, and the like.

The low temperature diluent serves to lower the viscosity of the epoxy and is used in the range of 0 to 10% by weight, preferably 5 to 10% by weight, in the upper sealer. The addition of a low temperature diluent can solve the problem in the molding process of the product due to the viscosity increase, and when the excessive use exceeds 10% by weight causes a flow problem due to the viscosity decrease.

The moisture absorbent and the flow inhibitor have been described above as the lower layer sealer composition. In the upper sealer, a hygroscopic agent is suitably 0 to 5% by weight, preferably 1 to 3.5% by weight, and a flow inhibitor is suitably 0 to 5% by weight, preferably 2 to 5% by weight.

As the colorant, the usual pigment component is 0 to 2% by weight, preferably 0.3 to 1% by weight.

In the following description, an example of applying the two-layer structure-coated steel sheet reinforcement sealer composition of the present invention including the lower sealer and the upper sealer to the wrong plate of a vehicle will be described in detail. The coating amount is applied to the lower layer sealer and the upper layer sealer in a weight ratio of 3: 1 to 1: 3, more preferably in a weight ratio of 1: 1 to 1: 1.5, and in order to increase the effect of shrinkage absorption, the size of the lower layer than the upper layer is increased. It is more preferable to apply a small 10 mm overall.

The coating method may be a method commonly applied in the field of painting, and is preferably an extruder type by using a slit nozzle to set the distance from the coating surface to about 2 to 3 mm. It is good to apply.

In particular, the steel sheet reinforcement sealer composition having a two-layer structure of the present invention can be applied to the inner or outer shell of a vehicle, and when used in an automobile outer shell, it is attached to the interior of the automobile outer panel so that panel deformation does not occur and driving noise occurs when driving a vehicle. It can be expected that the effect of reinforcing the strength of the steel sheet can be excellent.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention should not be construed as being limited to the following Examples.

EXAMPLES Preparation of Sealer Composition

Example 1 and Comparative Example 1.

Table 1 shows the composition of the lower sealer composition, and Table 2 shows the composition of the upper sealer composition. In addition, Comparative Example 1 is described based on the sealer composition disclosed in the Republic of Korea Patent Publication No. 2009-0099362.

Lower layer sealer composition Classification (% by weight) Example 1 Comparative Example 1 SBR ¹⁾ 0 30 NBR ²⁾ 20 0 EPDM Rubber 0 18.5 Epoxy resin ³⁾ 0 20 Curing agent ⁴⁾ 2 3 Vulcanizer ⁵⁾ 0 2 Chemical crosslinking agent ⁶⁾ 0.65 0.5 Vulcanization accelerator ⁷⁾ 0 One Physical blowing agent 0 0.7 Chemical blowing agents 0 0.5 Conductivity giving agent ⁸⁾ 0.5 0 Thermal Aging Agent ⁹⁾ 0.5 4.5 filling  Wollastonite 10 0  Calcium carbonate 14.35 4  Fatty Acid Coated Calcium Carbonate 22 0  Aluminum hydroxide 0 6 Polyester resin ¹⁰⁾ 0 2 Phthalate plasticizer ¹¹⁾ 25 7.3 additive Flow inhibitor ¹²⁾ 0 One Attachment agent ¹³⁾ 2 0.7 Absorbent ¹⁴⁾ 3 1.3 1) SBR: ISP ELASTOMER
2) NBR: Taekwang R & C
3) Epoxy Resin: YD-128, Kukdo Chemical
4) Hardener: OMICURE DDA-10, CVC SPECIALTY CHEMICALS, USA
5) Vulcanizer: Sulfur (S), Taekwang R & C
6) Chemical crosslinking agent: DCP-40, Human Tech
7) Vulcanization accelerator: DM, Taekwang R & C
8) Conductivity grant agent: EC 300JD, KETJEN, CARBON BLACK
9) Heat aging inhibitor: WINGSTAY-L, Mirae F
10) Polyester resin: TS-3000, lithoic acid
11) Phthalate plasticizer: DIDP, Aekyung Chemical
12) Flow inhibitor: Benton # 38, Newchem
13) Attachment: PS-610, Taekwang R & C
14) Absorbent: HPA-1, swimming material

Upper sealer composition Classification (% by weight) Example 1 Comparative Example 1 Epoxy resin BPA ¹⁾ 15 30 Dimer modified epoxy ²⁾ 0 20 Tetrafunctional epoxy ³⁾ 2 0 Trifunctional epoxy ⁴⁾ 2 0 CTBN modified epoxy ⁵⁾ 10 0 Polyester ⁶⁾ 7.5 0 Low temperature diluent ⁷⁾ 7.5 0 filling  Wollastonite 7.5 0  Calcium carbonate 24.1 16  Fatty Acid Coated Calcium Carbonate 15 5.5  Aluminum hydroxide 0 10 Hardener ⁸⁾ 3.5 15 Curing accelerator ⁹⁾ 0 One Separation inhibitor ¹⁰⁾ 1.5 0 additive Absorbent ¹¹⁾ 2.25 0.5 Flow inhibitor ¹²⁾ 0 One Toning Agents (Blue Pigments) ¹³⁾ 0.65 0 Conductivity imparting agent ¹⁴⁾ 0 1.5 Stabilizer ¹⁵⁾ 1.5 One 1) BPA: YD-128, Kukdo Chemical
2) Dimer modified epoxy: YD-272, Kukdo Chemical
3) Tetrafunctional epoxy: Chemical Formula 1, KDT-4400, Kukdo Chemical
4) Trifunctional Epoxy: Chemical Formula 2, YH-300, Kukdo Chemical
5) CTBN modified epoxy: KR-450, Kukdo Chemical
6) Polyester: TS-3000, Hanbaesan
7) Low temperature diluent: DIDP, Aekyung Chemical
8) Curing Agent: OMICURE DDA-10, CVC SPECIALTY CHEMICALS, USA
9) Curing accelerator: ANCAMINE 2014-AS, AIRPRODUCTS
10) Separation inhibitor: POLY BUTEN (BP-1400), Daelim
11) Hygroscopic: HPA-1, swimming material
12) Flow Retardant: Benton # 38
13) Colorant: KUT-490 BLUE, Daebo Chemical
14) Conductive Agent: EC 300JD, KETJEN, CARBON BLACK
15) Stabilizer: E-700, Wish Industry

[Experimental Example]

Experimental Example 1. Evaluation of Properties

The sealer composition prepared in Example 1 and Comparative Example 1 was applied to a steel sheet and then cured to prepare a specimen. In addition, the physical properties of each specimen were measured under the experimental conditions shown in Table 3 below, and the results are shown in Table 3 below.

Inspection items Requirements (MS 721-62) Example 1 Comparative Example 1 Upper floor (EPOXY) Lower Tier (RUBBER) Upper layer substratum Upper layer substratum importance 1.4 ± 0.1 1.4 ± 0.1 1.43 1.45 1.43 1.45 Solid content (%) 95 or higher Over 99 99.5 99.6 99.4 99.5 Viscosity (cps, at 26 ℃) 650,000 ± 5% 850,000 ± 5% 630,000 830,000 620,000 840,000 Pretreatment fluid contamination No contamination of liquid or dissolution of sealer clear clear Electrodeposition Contaminant No contamination of liquid or dissolution of sealer clear clear High Temperature Resistance, 1hr at 191 ℃ No CRACK or Aging clear clear Flowability
(4.6mm thick) Room temperature, 4hr No flow 0 0 163 ℃, 20 minutes (mm) 5 or less 0 0 Shear Adhesion (Thickness 0.5mm) (kgf / cm ² ) Initial state 100 kgf / ㎠ ↑ 25 ± 5 kgf / ㎠ 132 27 108 26 Moisture resistance 70 kgf / ㎠ ↑ 25 ± 5 kgf / ㎠ 133 26 104 26 Heat resistance 77 kgf / ㎠ ↑ 25 ± 5 kgf / ㎠ 143 28 102 28 Shear Adhesion (Thickness 0.5mm)
(kgf / cm ² ) HEAT CYCLE 70 kgf / ㎠ ↑ 25 ± 5 kgf / ㎠ 138 29 105 29 Salt spray 77 kgf / ㎠ ↑ 25 ± 5 kgf / ㎠ 125 28 125 25 Flexural Strength (thickness 2.0mm) (kgf) Initial state 6.0 kgf ↑ 9.1 5.2 Moisture resistance 4.5 kgf ↑ 9.2 5.4 Heat resistance 5 kgf ↑ 8.8 5.7 HEAT CYCLE 5 kgf ↑ 9.3 5.4 Salt spray 4.5 kgf ↑ 9.3 5.3 Sheet metal deformation No abnormality such as deformation of OTR PNL clear clear Corrosion Resistance / Salt Spray No corrosion by the naked eye clear clear Domestic time (日) 3 or more clear clear Impact resistance
(time) Initial state over 10 clear clear Moisture resistance clear clear Heat resistance clear clear HEAT CYCLE clear clear Water resistance clear clear Salt spray clear clear Low temperature impact (times) 8 or more clear clear Dustproof (d) 0.02 or more 0.0862 0.0270 Cold
Flexibility Psalter 0.3 to 1.7mm 0.4 or less 1.6 or less part No bending occurs clear clear Absorption Rate (%) Less than 5% 0.5 0.8  Environmentally harmful substances Meet the requirements of MS201-02 clear clear

According to the results of Table 3, it can be seen that compared with the specimen of Comparative Example 1, the specimen of Example 1 maintains physical properties such as adhesive strength and flexural strength, and has improved excellent cold resistance and vibration resistance (dust damping). .

Experimental Example 2

1) MS SPEC standard condition measurement (bending strength)

After applying the sealer composition for reinforcing the steel sheet of Example 1 and Comparative Example 1 and curing the specimen obtained by curing at 180 ° C. × 20 minutes + 150 ° C. × 20 minutes (twice), as shown in FIG. It is shown in Table 4 below.

Test Items Requirements (MS-721-62) Example 1 Comparative Example 1 Flexural strength
(Thickness 2.0mm) (kgf) Initial state 6.0 kgf ↑ 9.1 5.2 Moisture resistance 4.5 kgf ↑ 9.2 5.4 Heat resistance 5 kgf ↑ 8.8 5.7 HEAT CYCLE 5 kgf ↑ 9.3 5.4 Salt spray 4.5 kgf ↑ 9.3 5.3

2) MS SPEC shooting condition measurement (vibration resistance)

After applying the steel sheet reinforcement sealer compositions of Example 1 and Comparative Example 1, the specimen obtained by curing 180 ° C. × 20 minutes + 150 ° C. × 20 minutes (twice) was shown in FIG. 2. It is shown in Table 5 below.

Test Items Requirements (MS-721-62) Example 1 Comparative Example 1 Exam conditions Dustproof 0.02 or more 0.0862 0.0270 MS721-60

3) Measurement of MS SPEC standard condition (cold resistance flexural specimen)

After applying the steel sheet reinforcement sealer compositions of Example 1 and Comparative Example 1 and curing the specimen obtained by curing at 180 ° C. × 20 minutes + 150 ° C. × 20 minutes (twice), as shown in FIG. It is shown in Table 6 below.

Test Items Requirements
(MS-721-62) Example 1 Comparative Example 1 Exam conditions Cold resistance -30 ℃, specimen 0.3-1.7 mm 0.4 (max) 1.6 (max) MS-721-60

4) Measurement of MS SPEC specification conditions (auto parts)

 After applying the sealer composition for reinforcing the double-structured steel sheet of Example 1 and Comparative Example 1 and confirming the sealer deformation degree as shown in Figure 4 attached to the parts obtained by passing through the electrodeposition oven of the actual Hwa Hung Kia automobile body part 2 production line It is shown in Table 6 below.

Test Items Requirements (MS-721-62) Example 1 Comparative Example 1 Exam conditions Cold resistance part No bending occurs 0.4 (max) 1.6 (max) MS-721-60

It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention. Accordingly, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (14)

Lower layer sealers including NBR (acrylonitril-butadiene rubber) rubbers, chemical crosslinkers, conductivity giving agents, hardeners, fillers, anti-aging agents, hygroscopic agents, and plasticizers; And
An upper sealer comprising a tetrafunctional epoxy resin, a trifunctional epoxy resin, a bisphenol-A (BPA) epoxy resin, a rubber modified epoxy resin, a polyester, a curing agent, a filler, an antisegregating agent, a moisture absorbent, a colorant, and a stabilizer;
Sealer composition for reinforcing steel sheet having a two-layer structure comprising a.
The method according to claim 1,
The lower layer sealer is 20-40% by weight of NBR rubber, 0.2-1.5% by weight of chemical crosslinking agent, 0.2-1.0% by weight of conductivity imparting agent, 1-3% by weight of curing agent, 10-20% by weight of needle filler, 5-15% by weight filler. %, Spherical filler 15-30% by weight, heat aging inhibitor 0.1-2% by weight, moisture absorbent 2-5% by weight, and plasticizer 20-45% by weight,
The upper layer sealer is 0.5 to 3.5% by weight of the tetrafunctional epoxy resin, 0.5 to 3.5% by weight of the trifunctional epoxy resin, 10 to 20% by weight of the BPA (bisphenol-A) epoxy resin, 5 to 15% by weight of the rubber-modified epoxy resin, 5 to 10 wt% polyester, 1 to 6 wt% hardener, 5 to 10 wt% needle filler, 15 to 30 wt% bulk filler, 10 to 20 wt% spherical filler, 1.0 to 3.0 wt% separation inhibitor, 1 to 3 moisture absorbent A sealer composition for reinforcing steel sheets having a two-layer structure comprising 3.5% by weight, 0.3 to 1% by weight of a colorant, and 1 to 2% by weight of a stabilizer.
The method according to claim 1 or 2,
The ratio of the lower layer sealer and the upper layer sealer has a weight ratio of 3: 1 to 1: 3, the sealer composition for reinforcing steel sheet having a two-layer structure.
The method according to claim 1 or 2,
The chemical crosslinking agent included in the lower layer sealer is dibenzothiazyl disulfide, tetramethylthiuram disulfide, or dicumyl peroxide.
The method according to claim 1 or 2,
The conductivity-imparting agent included in the lower layer sealer is electroless plated on the surface of carbon black, PAN-based carbon fiber, metal powder, metal fiber, metal flake, mica or glass fiber, antimony-coated tin oxide of titanium oxide. Sealer composition for reinforcing steel sheets having a two-layer structure, characterized in that the surface treatment is at least one selected from potassium carbonate and zinc oxide.
The method according to claim 1 or 2,
The hardening agent contained in the lower layer sealer is a dicyane diamide sealant composition for reinforcing steel sheet having a two-layer structure.
The method according to claim 1 or 2,
The anti-aging agent included in the lower layer sealer is a 2,2'-methylene-bis (4-methyl-6-tert-butylphenol) characterized in that the steel sheet reinforcement sealer composition having a two-layer structure.
The method according to claim 1 or 2,
The tetrafunctional epoxy contained in the upper sealer is a 1,1,2,2-tetrakis (4- (oxirane-2-yloxy) phenyl) ethane sealant for reinforcing steel sheets having a two-layer structure, characterized in that Composition.
The method according to claim 1 or 2,
The trifunctional epoxy resin contained in the upper sealer is a two-layer, characterized in that 2-((2,2-bis (((oxirane-2-yl) methoxy) methyl) butoxy) methyl) oxirane Sealer composition for reinforcing steel sheet having a structure.
The method according to claim 1 or 2,
The rubber-modified epoxy resin included in the upper sealer is a CTBN (carboxyl terminated butadiene acrylonitrile rubber) modified epoxy resin, characterized in that the steel sheet reinforcement sealer composition having a two-layer structure.
The method according to claim 1 or 2,
The anti-separation agent included in the upper sealer is a 2,2'-methylene-bis (4-methyl-6-tert-butylphenol), the sealant composition for reinforcing steel sheet having a two-layer structure.
The method according to claim 1 or 2,
The stabilizer included in the upper sealer is a monoepoxide oil, a soybean oil, or a titanate-based oil sealant composition for reinforcing steel sheet having a two-layer structure.
The method according to claim 1 or 2,
The filler included in each of the lower sealer and the upper sealer is a sealant composition for reinforcing steel sheets having a two-layer structure, characterized in that at least one selected from calcium carbonate, aluminum hydroxide, fatty acid coated filler, silicate, and wollastonite.
The method according to claim 1 or 2,
The moisture absorbent included in each of the lower sealer and the upper sealer is calcium oxide, ash, liquid calcium oxide, or quicklime.

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