KR101282624B1 - Sealer Composition for body reinforcement - Google Patents

Abstract

The present invention relates to a one-component steel sheet reinforcement sealer composition, and more particularly, to a composition containing an epoxy resin, a modified epoxy resin, a polyurethane prepolymer, a curing agent, a filler, an impact modifier, and a reactive diluent, at a low temperature when applied to a steel sheet. The present invention relates to a one-component steel sheet reinforcement sealer composition which prevents shrinkage under the condition and improves mechanical properties such as flexural strength, moisture resistance, impact resistance, and shear strength and can be very bonded to a sealer composition for automobile steel sheet reinforcement.

Sealer, Epoxy, Alumina, Steel Sheet, Automotive, Moisture Resistance, Shear Strength

Description

One-component steel sheet reinforcement sealer composition {Sealer Composition for body reinforcement}

The present invention relates to a one-component steel sheet reinforcement sealer composition, and more particularly, to a composition containing an epoxy resin, a modified epoxy resin, a polyurethane prepolymer, a curing agent, a filler, an impact modifier, and a reactive diluent, at a low temperature when applied to a steel sheet. The present invention relates to a one-component steel sheet reinforcement sealer composition which prevents shrinkage under the condition and improves mechanical properties such as flexural strength, moisture resistance, impact resistance, and shear strength and can be very bonded to a sealer composition for automobile steel sheet reinforcement.

In general, the coated steel sheet reinforcement used in automobile bodies, doors, etc. to reinforce the outer shell rigidity of the vehicle body is a paste-like product is applied by the robot. A feature of the coated steel sheet reinforcement is to implement a function as a coated steel sheet reinforcement through the process of implementing the adhesive force by curing in the electrodeposition drying furnace without dissolving in the electrodeposition liquid tank process.

Major components of the coated steel sheet reinforcement can be roughly divided into epoxy resin and filler. Epoxy resin has excellent physical properties such as excellent adhesion, mechanical properties, chemical resistance, and shrinkage deformation occurs less than other resins during the curing reaction and there is no by-product generation. However, due to the poor properties under high temperature and high density of crosslinking, it is easily broken due to physical properties that can be easily broken.

Therefore, the conventional coated steel sheet reinforcing agent contains other additives and resins, in addition to the epoxy resin to compensate for these disadvantages, and aims to improve the cold-resistant strain and impact resistance. However, since there are limited factors in the use of raw materials, there is a problem in that the quality of the product is not uniform depending on the conditions of the external environment such as high humidity hardening and summer moisture and winter cold problems. . In particular, the existing epoxy resin is a form that is cured by heat, and heat resistance and aging resistance are unstable when heated, and there is a point that expansion and contraction occurs due to heat, so that a bending phenomenon (DENT) occurs or a low temperature region (- There is a problem that the shrinkage phenomenon of the steel sheet in 30 ℃ or less) occurs.

Therefore, bending phenomenon at the interface of automobile steel sheet and shrinkage of steel sheet at low temperature region do not occur, and mechanical properties such as bending strength, moisture resistance, impact resistance, and shear strength are improved, so it can be used as a sealer composition for automobile steel sheet reinforcement. There is an urgent need for the development of a one-component steel sheet reinforcement sealer composition.

Accordingly, the inventors of the present invention believe that existing epoxy resins are hardened by heat, and thus, heat resistance and aging resistance are unstable at heating, and expansion and contraction may occur due to heat, thereby causing bending (DENT) at the interface of the automotive steel sheet. Efforts have been made to solve the problem of shrinkage of the steel sheet in the low temperature region (below -30 ℃).

As a result, a composition containing epoxy resin, modified epoxy resin, polyurethane prepolymer, hardener, filler, impact modifier, and reactive diluent prevents shrinkage at low temperatures, and has mechanical properties such as flexural strength, moisture resistance, impact resistance, and shear strength. This improved steel sheet reinforcement sealer composition was completed.

Therefore, the present invention does not occur the phenomenon of bending at the interface of the automotive steel sheet and shrinkage of the steel sheet in the low temperature region, the mechanical properties such as bending strength, moisture resistance, impact resistance and shear strength is improved to the sealer composition for automobile steel sheet reinforcement It is an object to provide a one-part steel sheet reinforcement sealer composition that can be used very bonded.

The present invention is 15 to 25% by weight bisphenol A epoxy resin having an equivalent weight of 180 to 200, butadiene acrylonitrile modified epoxy resin having an amine end group 3 to 17% by weight, butadiene acrylonitrile modified epoxy having a carboxyl end group Poly-containing 13-22 wt% resin, 2-4 wt% polyurethane prepolymer, 1-2 wt% hardener, 36-56 wt% filler, 1.5-4 wt% impact modifier and 3-7 wt% reactive diluent The propylene composition is characterized.

Hereinafter, the present invention will be described in detail.

Conventionally, a composition in which epoxy resins and polyester resins are added is known, but the bending phenomenon at the interface of automobile steel sheet and the shrinkage of the steel sheet in the low temperature region do not occur, and the flexural strength, moisture resistance, and impact resistance according to the present invention. And sealer compositions having improved mechanical properties such as shear strength are absent.

Therefore, the present invention contains epoxy resin, modified epoxy resin, polyurethane prepolymer, curing agent, filler, impact modifier, and reactive diluent so that bending phenomenon at the interface of automobile steel sheet and shrinkage of steel sheet at low temperature region do not occur and bending strength It is a one-component steel sheet reinforcement sealer composition that can be applied as an automobile steel reinforcement with improved mechanical properties such as moisture resistance, impact resistance and shear strength.

When explaining the one-component steel sheet reinforcement sealer composition of the present invention in more detail as follows.

Bisphenol A epoxy resin used in the present invention serves to always maintain the adhesion and strength. When the amount of the epoxy resin is used in the range of 15 to 25% by weight, the shear adhesion is lowered when the amount is less than 15% by weight, and when the amount is more than 25% by weight, the adhesive strength is excellent, but the impact strength becomes worse. .

Butadiene acrylonitrile-modified epoxy having an amine end group used in the present invention (Amine Terminated Butadiene Acrylonitrile, hereinafter referred to as ATBN resin) resin serves to improve the moisture resistance, the amount of the epoxy resin used is 3 to 17 weight When used in the% range, the moisture resistance may worsen when less than 3% by weight, when the moisture content is more than 17% by weight, the problem occurs that the adhesion is bad.

Carboxyl Terminated Butadiene acrylonitrile (hereinafter referred to as CTBN resin) resin having a carboxyl end group used in the present invention is used to improve impact resistance and to prevent shrinkage at low temperatures (-30 ° C). , The amount of the CTBN resin is used in the range of 13 to 22% by weight, the flexibility is lowered when less than 13% by weight, when more than 22% by weight, the adhesive strength is excellent after curing, but the flexural strength is bad due to the high flexibility.

Polyurethane pre-polymer used in the present invention is used to increase the adhesive force, 10 to 17 parts by weight of polyisocyanate in 100 parts by weight of polyester or polyether polyol 2 to 4 under 110 to 130 ℃ nitrogen atmosphere Prepared by polymerization for hours. When the polyisocyanate is less than 10 parts by weight with respect to 100 parts by weight of the polyester or polyether polyol, the adhesive strength is insufficient, and when the amount is more than 17 parts by weight, the adhesive strength is increased, but the cold resistance shrinkage is increased. . Among the polyisocyanates, it is more effective to use toluene diisocyanate (TDI) series as the polyisocyanate series, and the amount of the polyurethane prepolymer is used in the range of 2 to 4% by weight, and the adhesion is less than 2% by weight. It becomes insufficient, when more than 4% by weight the adhesive strength is good but the moisture resistance is bad.

The curing agent used in the present invention is a latent curing agent, which causes a curing reaction at a temperature of 160 ° C. or higher to form an epoxy in a three-dimensional network structure, and it is more effective to use dicyandiamide series. The amount of the curing agent is in the range of 1 to 2% by weight, it is difficult to occur when less than 1% by weight, If it exceeds 2% by weight, the excessive use of the hardener causes a problem that can easily be broken due to high shrinkage and strength in the product.

The filler used in the present invention is used in the art and does not specifically limit its components, but it is effective to use one or two or more kinds selected from calcium carbonate, silicon oxide, carbon black, alumina, wollastonite, and the like. The content of the filler is used in the range of 36 to 56% by weight, the hardness is lowered when less than 36% by weight, and when it exceeds 56% by weight the hardness is easily broken problem occurs.

As the impact modifier used in the present invention, it is more effective to use one or two kinds of mixtures selected from acrylonitrile butadiene terpolymer copolymer resin and methyl methacrylate butadiene rubber styrene terpolymer copolymer resin as a thermoplastic resin. More preferably, it is more effective to use methyl methacrylate butadiene rubber styrene terpolymer copolymer resin. The use of the impact modifier is used in the range of 1.5 to 4% by weight, the impact resistance is lowered when less than 1.5% by weight, the entanglement occurs when passing through the nozzle when the weight is greater than 4% by weight, the ejectability of the equipment is reduced.

The reactive diluent used in the present invention can obtain plasticity by adjusting the viscosity of the product, and in the present invention, it is more effective to use benzyl alcohol having excellent plasticity. The content of the reactive diluent is used in the range of 3 to 7% by weight, it is difficult to adjust downward in viscosity adjustment when less than 3% by weight, when the viscosity exceeds 7% by weight, there is a problem that appears after the coating flow occurs after application.

In the present invention, a rheology imparting agent, an adhesion imparting agent, etc. may be further administered in addition to the above components.

The method for producing a one-component steel sheet reinforcement sealer composition of the present invention first reacts CTBN resin with an epoxy resin under a nitrogen atmosphere at 110 to 130 ° C. for 3 to 5 hours to complete a resin having an equivalent number of 450 to 550, and epoxy resin to ATBN resin. The resin was mixed at room temperature and left for 14 days at a temperature of 20 to 30 ° C. to complete the resin, and a polyurethane prepolymer was prepared by reacting the polyester polyol and diisocyanate under a nitrogen atmosphere at 110 to 130 ° C. for 2 to 4 hours. After the raw material prepared above and the filler, hardener, impact modifier, reactive diluent can be mixed in a mixer for 60 to 180 minutes at a speed of 800 ~ 1200 rpm under 40 ~ 60 ℃ to obtain a composition.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

The symbol of an Example and a comparative example means the following content.

1. Resin

1) Epoxy: Bisphenol A epoxy resin

2) ATBN: Butadiene acrylonitrile-modified epoxy resin having amine end groups

3) CTBN: Butadiene acrylonitrile-modified epoxy resin having a carboxyl end group

4) Prepolymer: Polyurethane prepolymer prepared by reacting polyester polyol and diisocyanate for 3 hours at 120 ℃ nitrogen atmosphere

5) Rubber modification: Rubber modified epoxy resin (NBR modified)

6) Hardener: Dicyandiamide

7-1) Calcium Carbonate: Calcium Carbonate

7-2) Silicon Oxide: Silicon Oxide

7-3) Carbon Black: Carbon Black

7-4) Alumina: Alumina

8) Impact modifier: MBS resin (product of LG Chemical MB830).

9) Reactive Diluent: Benzyl Alcohol

Examples 1 and 2 and Comparative Example 1

1 to 5 parts by weight of butadiene / acrylonitrile (Noveon, Hycar ATBN 1300 X 16) having an amine group with respect to 100 parts by weight of bisphenol A-type epoxy resin (equivalent number 190) as shown in Table 1 It was prepared by mixing in a secondary range and left for 14 days at 20 ~ 30 ℃, butadiene / acrylonitrile (Noveon, Hycar CTBN 1300 X 13) having a carboxyl group and a bisphenol A epoxy resin (equivalent number 190) 120 After 4 hours of reaction under a nitrogen atmosphere at 3 ° C., the polyester polyol and the diisocyanate were reacted for 3 hours under a nitrogen atmosphere of 120 ° C., and then the reactants, the curing agent, the filler, the impact modifier, and the reactive diluent obtained at 40 ° C. to 60 ° C. were used. The composition was completed by stirring at a speed of 800 ~ 1200 RPM at and the results after the test according to the test examples are shown in Table 2 below.

Comparative Example 2 to Comparative Example 4

The same procedure as in Example 1, except that the composition was prepared as shown in Table 1 below, and the results after the test according to the following test example are shown in Table 2 below.

Test Example

1. Low temperature shrinkage (-30 ° C.): measured by the method of MS 721-60. Apply sealer (150 × 200 mm) to steel plate (300 × 300 mm) with standard thickness (1.5 mm) and leave at least for 6 hours under curing conditions (electrodeposition, medium / top coat) of each factory, and then -30 ℃ / 30 Leave on for a minute and measure the deformation of each part in -30 ℃ and record the minimum and maximum values. The measuring method is to place the iron plate on the horizontal plane and measure the height difference between the horizontal plane and the iron plate.

2. Flexural strength: measured by MS 721-60 method. The tension test is terminated by applying a load at a rate of 5 mm / min on the tensile tester.

3. Moisture resistance: measured by MS 721-60 method. Measured through 100 mm × 300 mm specimens obtained by curing at 180 ° C for 20 minutes and 150 ° C for 20 minutes (twice) after 3 days, 5 days, 7 days, and 10 days at 40 ° C × 95% RH. It was.

4. Impact resistance: 50 × 100 × 2.0 mm in the center of the steel sheet of 100 × 300 mm by applying a sealer to heat-harden. The test piece was naturally dropped at an angle of 90 °, and the presence or absence of abnormality in appearance such as cracking and cracking of the sealer was checked. When no abnormality was found, the number of specimens was sequentially increased and the number of occurrences of abnormality in appearance was measured.

5. Shear strength (㎏f / ㎠): The heat-hardened specimens were subjected to tensile load in the direction of 180˚ at a speed of 5 mm / min.

division Low temperature shrinkage
(-30 ° C) Flexural strength
(kg _f ) Moisture resistance Impact resistance Shear strength
(Kgf / cm2) Example 1 1.2 mm 5.5 7 days 15th 180 Example 2 1.2 mm 5.3 7 days 15th 178 Comparative Example 1 1.6 mm 5.0 3 days 10 times 150 Comparative Example 2 1.6 mm 4.7 2 days 9 times 147 Comparative Example 3 1.7 mm 4.2 (Sample Break) 2 days 6 times 132 Comparative Example 4 1.4 mm 4.8 3 days 10 times 165

As shown in Table 2, the sealer compositions of Examples 1 to 2 according to the present invention have excellent flexural strength and low temperature shrinkage rate compared to Comparative Examples 1 to 4, and have mechanical properties such as moisture resistance, impact resistance and shear strength. It can be confirmed that it is superior to the conventional steel sheet sealer composition.

As described above, the one-component steel sheet reinforcement sealer composition of the present invention has excellent flexural strength and low-temperature shrinkage rate as compared with the conventional sealer composition, and mechanical properties such as moisture resistance, impact resistance, and shear strength are different from those of the sealer composition. It can be used to bond very well as a sealer composition for automobile steel sheet reinforcement in comparison.

Claims (6)

A) 15 to 25% by weight bisphenol A epoxy resin having an equivalent weight of 180 to 200; B) 3 to 17% by weight of butadiene acrylonitrile-modified epoxy resin having amine end groups; C) 13 to 22% by weight of butadiene acrylonitrile-modified epoxy resin having carboxyl end groups; D) 2-4 weight percent polyurethane prepolymer; E) 1-2 weight percent of hardener; F) 36-56 weight percent filler; G) impact modifier 1.5-4% by weight; And H) A one-component steel sheet reinforcement sealer composition comprising 3 to 7% by weight of a reactive diluent. The method of claim 1, The polyurethane prepolymer is a one-component steel sheet reinforcement sealer composition, characterized in that 10 to 17 parts by weight of polyisocyanate is mixed with 100 parts by weight of polyester or polyether polyol. The method of claim 1, The hardener is a one-component steel sheet reinforcement sealer composition, characterized in that the dicyandiamide-based. The method of claim 1, The filler is a one-component steel reinforcement sealer composition, characterized in that the calcium carbonate, silicon oxide, carbon black, alumina and wollastonite selected from one or two or more. The method of claim 1, The impact modifier is a one-component steel sheet reinforcement sealer composition, characterized in that the mixture of one or two selected from acrylonitrile butadiene terpolymer copolymer resin and methyl methacrylate butadiene rubber styrene terpolymer copolymer resin. The method of claim 1, The reactive diluent is benzyl alcohol, one-component steel reinforcement sealer composition, characterized in that.