Title of Invention: Composite resin composition for fuel tank steel sheet, composite resin coated steel sheet using same, and manufacturing method thereof
technical field
[One]
The present invention relates to a composite resin composition for a fuel tank steel sheet, a composite resin coated steel sheet using the same, and a method for manufacturing the same.
background
[2]
In general, materials for fuel tanks have high safety, heat resistance, durability, fuel permeability and design freedom, and are required to have characteristics suitable for reducing the weight of automobiles. In general, as a material for an internal combustion engine fuel tank, plastic occupies 70% and steel sheet occupies about 30%.
[3]
Plastic materials are widely used because of their light weight and the advantage of being able to be molded to fit various structures of automobiles. However, plastics are not easy to dispose of wastes containing spent fuel, and due to the permeability of fuels, there is a limit to satisfying the Global Emissions Regulations Act (Euro-VI).
[4]
On the other hand, STS or Al-Si (8%) alloy hot-dip galvanized steel sheets are widely used as steel sheets for fuel tanks applied to diesel commercial vehicles. Some automobile manufacturers use Zn-Fe alloy hot-dip or Zn electroplated steel sheets. Although the steel sheet has excellent properties as a fuel tank material, the STS steel sheet has a disadvantage in that it is expensive to manufacture, and the Al-Si plated steel sheet has a disadvantage in that the corrosion resistance of the exposed part after processing is weak and alkaline conditions. In addition, Zn-Fe alloy hot-dip galvanized steel sheet and Zn electroplated steel sheet have weak corrosion resistance and fuel resistance.
[5]
Therefore, in order to solve the above problems, it is required to develop an excellent material that can replace expensive plastic fuel tanks because of its low manufacturing cost and eco-friendly properties as well as excellent properties.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[6]
The present invention has been devised to solve the above problems, and has excellent properties such as corrosion resistance, weldability and fuel resistance, and a composite resin composition for fuel tank steel sheet with excellent price competitiveness, composite resin coated steel sheet using the same, and manufacturing thereof to provide a way.
means of solving the problem
[7]
According to one aspect of the present invention, based on the total weight of the composite resin composition, 10 to 20% by weight of the polymer resin; 1 to 10% by weight of a curing agent; 1-10 wt% of anti-corrosion additive; Adhesion enhancer 0.5 to 10% by weight; 0.5-10 wt% of a conductive additive; And it provides a composite resin composition for a fuel tank steel sheet containing the remaining solvent.
[8]
The steel sheet may be a Zn—X alloy hot-dip galvanized steel sheet, where X means two or more elements selected from the group consisting of Al, Mg, Ni and Si.
[9]
The Zn-X alloy may contain 1 to 20 parts by weight of element X based on 100 parts by weight of Zn.
[10]
The adhesion promoter may include a unit structure represented by the following formula (1).
[11]
[Equation 1]
[12]

[13]
(In Formula 1, R is vinyl (vinyl), 2- (3,4-epoxycyclohexyl) ethyl (2- (3,4-epoxycyclohexyl) ethyl), 3-glycidoxypropyl (3-glycidoxypropyl), p- Styrenyl (p-styrenyl), 3-methacryloxypropyl (3-methacryloxypropyl), 3-acryloxypropyl (3-acryloxypropyl), N-2- (aminoethyl) -3-aminopropyl (N-2- ( aminoethyl)-3-aminopropyl), 3-aminopropyl (3-aminopropyl) and N-phenyl-3-aminopropyl (N-phenyl-3-aminopropyl)
[14]
The conductive additive may include 0.3 to 7% by weight of a metal and 0.2 to 3% by weight of a surfactant.
[15]
The metal may be at least one selected from the group consisting of silver, aluminum, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, palladium, platinum, tin, tungsten, and zinc.
[16]
The metal may have an average particle diameter of 10-900 nm.
[17]
wherein the surfactant is composed of fatty acid alkali salt, fatty acid ammonium salt, alkyl sulfate salt, alkyl ether sulfate salt, alkyl phenol ethoxylate sodium salt, alkyl phenol ethoxylate ammonium salt, polyoxyethylene fatty acid ester and polyoxyethylene sorbitan fatty acid ester It may be one or more selected from the group.
[18]
The fatty acid alkali salt and fatty acid ammonium salt may include a unit structure represented by the following formula (2).
[19]
[Equation 2]
[20]

[21]
(In Formula 2, R' and R'' each independently mean a chain-type alkyl group having 5 to 15 carbon atoms.)
[22]
The alkyl sulfate salt may include a unit structure represented by the following formula (3).
[23]
[Equation 3]
[24]

[25]
(In Formula 3, R means a chain alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[26]
The alkyl ether sulfate salt may include a unit structure represented by the following formula (4).
[27]
[Equation 4]
[28]

[29]
(In Formula 4, R means a chain alkyl group having 1 to 10 carbon atoms, and n is an integer from 1 to 10.)
[30]
The polyoxyethylene fatty acid ester may include a unit structure represented by the following formula (5).
[31]
[Equation 5]
[32]

[33]
(In Formula 5, R denotes a chain-type alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[34]
The polyoxyethylene fatty acid ester may include a unit structure represented by the following formula (6).
[35]
[Equation 6]
[36]

[37]
(In Formula 6, R means a chain alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[38]
According to another aspect of the present invention, a steel plate; a plating layer formed on at least one surface of the steel sheet; and a composite resin coating layer formed on the plating layer, wherein the composite resin coating layer is based on the total weight of the composite resin composition, 10 to 20% by weight of a polymer resin, 1 to 10% by weight of a curing agent, 1 to 10% by weight of an anticorrosion additive , 0.5 to 10% by weight of an adhesion promoter, and 0.5 to 10% by weight of a conductive additive; A composite resin-coated steel sheet for a fuel tank is provided, which includes a.
[39]
The plating layer may contain 1 to 20 parts by weight of element X based on 100 parts by weight of Zn, where X means two or more elements selected from the group consisting of Al, Mg, Ni and Si.
[40]
A single-sided plating amount of the plating layer may be 10 to 60 g/m 2 .
[41]
The thickness of the composite resin coating layer may be 0.1 ~ 1.5㎛.
[42]
The adhesion amount of the composite resin coating layer may be 0.1 to 2.0 g/m 2 .
[43]
According to another aspect of the present invention, the method comprising: forming a plating layer on at least one surface of a steel sheet; applying a composite resin composition on the plating layer; and curing the applied composite resin composition, wherein the composite resin composition contains 10 to 20% by weight of a polymer resin based on the total weight of the composite resin composition; 1 to 10% by weight of a curing agent; 1-10 wt% of anti-corrosion additive; Adhesion enhancer 0.5 to 10% by weight; 0.5-10 wt% of a conductive additive; And there is provided a method for manufacturing a composite resin-coated steel sheet for a fuel tank comprising the remaining solvent.
[44]
The plating layer may contain 1 to 20 parts by weight of element X based on 100 parts by weight of Zn, where X means two or more elements selected from the group consisting of Al, Mg, Ni and Si.
[45]
The conductive additive may be prepared by dispersing a mixture containing 0.3 to 7% by weight of a metal and 0.2 to 3% by weight of a surfactant using a high-speed bead mill.
[46]
The curing may be carried out at 100 to 180 ℃.
Effects of the Invention
[47]
The composite resin composition of the present invention has excellent weldability by improving adhesion to the plating layer and liquid metal embrittlement (LME) phenomenon. In addition, the steel sheet to which the composite resin composition is applied has excellent deep workability and weldability, as well as excellent corrosion resistance when using diesel fuel, biodiesel and aged diesel fuel.
Brief description of the drawing
[48]
1 schematically shows a cross-section of a composite resin-coated steel sheet according to an embodiment of the present invention.
[49]
Figure 2 schematically shows the high-speed bead mill used for the preparation of the conductive additive of the present invention and the dispersion liquid flow in the high-speed bead mill.
Best mode for carrying out the invention
[50]
Hereinafter, preferred embodiments of the present invention will be described with reference to various examples. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.
[51]
The present invention relates to a composite resin composition for a fuel tank steel sheet, a composite resin coated steel sheet using the same, and a method for manufacturing the same.
[52]
According to one aspect of the present invention, based on the total weight of the composite resin composition, 10 to 20% by weight of the polymer resin; 1 to 10% by weight of a curing agent; 1-10 wt% of anti-corrosion additive; Adhesion enhancer 0.5 to 10% by weight; 0.5-10 wt% of a conductive additive; And it provides a composite resin composition for a fuel tank steel sheet containing the remaining solvent.
[53]
The steel sheet applicable to the present invention is not particularly limited, and may be a generally used cold-rolled steel sheet. However, the cold-rolled steel sheet cannot be used for fuel tanks because of its weak corrosion resistance.
[54]
In order to strengthen corrosion resistance and apply it to a fuel tank, in the present invention, a Zn-X alloy hot-dip plated steel sheet, that is, a steel sheet in which a hot-dip plated layer made of a Zn-X alloy is formed on at least one surface of the steel sheet may be used. Here, X means two or more elements selected from the group consisting of Al, Mg, Ni and Si.
[55]
The Zn-X alloy preferably contains 1 to 20 parts by weight of at least two elements selected from the group consisting of Al, Mg, Ni and Si based on 100 parts by weight of Zn. When it is less than 1 part by weight, the improvement of physical properties by the alloy cannot be obtained, and when it exceeds 20 parts by weight or more, the alloying ratio is increased to deteriorate operability as well as increase the cost.
[56]
The temperature of the fuel in the fuel tank rises to 90° C. or higher during vehicle driving, and the polymer resin has excellent heat resistance and chemical resistance to the fuel. The polymer resin preferably has at least one selected from urethane, acryl, ester, and epoxy copolymer urethane having a number average molecular weight of 5000 to 50000 and a Tg of 10 to 50°C. The molecular structure of the polymer resin may contain a chain type, a crosslink type, and an aromatic group.
[57]
The polymer resin is preferably included in an amount of 10 to 20% by weight of the total composition. When the content is less than 10% by weight, the ductility of the coating layer is insufficient and the workability is inferior. On the other hand, when the content exceeds 20% by weight, the degree of curing is low and the hardness of the coating layer is lowered. There is a problem that the coating layer is pushed during processing.
[58]
The curing agent reacts with the polymer resin to form a dense three-dimensional network structure, thereby securing fuel resistance and corrosion resistance. The curing agent used in the present invention is not particularly limited, but it is preferably at least one of a melamine-based curing agent having excellent reactivity, an amine-based curing agent such as argidine, and isocyanate. In addition, the melamine-based curing agent among the curing agents is preferably at least one of melamine, butoxymethyl melamine, hexamethoxymethyl melamine and trimethoxymethyl. The isocyanate may be a compound of the structure RN=C=O (wherein R is -CH 3 , -CH 2 CH 3 , -CH 2 CH 2 CH 3 or -Ph).
[59]
It is preferable to contain the curing agent in an amount of 1 to 10% by weight. If the content is less than 1% by weight, the curing reaction does not completely occur during the dry coating of the composite resin coating layer, so that the physical properties of the coating layer are likely to be inferior. On the other hand, when the content exceeds 15% by weight, the hardness of the coating layer is too high, and there is a problem in that processing properties deteriorate, which is not preferable.
[60]
A silica compound is added to the corrosion resistance additive added to the composite resin composition in order to improve the corrosion resistance of the dried coating film. Examples of the silica compound are not limited thereto, but at least one selected from the group consisting of lithium polysilicate, sodium polysilicate, potassium polysilicate and colloidal silica may be used.
[61]
The content of the anticorrosion additive is preferably 1 to 10% by weight. If the content is less than 1% by weight, the corrosion resistance effect is insufficient. have.
[62]
In the present invention, the adhesion promoter may include a silane compound substituted with borazine (BN) in order to improve workability as well as adhesion between the composite resin coating layer and the coating film, and may include a unit structure represented by the following formula 1 can
[63]
[Equation 1]
[64]

[65]
In Formula 1, R is vinyl (vinyl), 2- (3,4-epoxycyclohexyl) ethyl (2- (3,4-epoxycyclohexyl) ethyl), 3-glycidoxypropyl (3-glycidoxypropyl), p- Styrenyl (p-styrenyl), 3-methacryloxypropyl (3-methacryloxypropyl), 3-acryloxypropyl (3-acryloxypropyl), N-2- (aminoethyl) -3-aminopropyl (N-2- ( aminoethyl) -3-aminopropyl), 3-aminopropyl (3-aminopropyl) and N-phenyl-3-aminopropyl may be at least one selected from the group consisting of, and include the following unit structures may be doing
[66]

[67]
The silane compound substituted with borazine has a property of strongly bonding with the M-OH bond of the metal surface, so it has the effect of greatly improving the adhesion of the composite coating film and has excellent lubricity. The adhesion enhancer is preferably included in an amount of 0.5 to 10% by weight, and when the content is less than 0.5% by weight, the adhesion enhancing effect is insufficient, and processing blackening during deep processing is inferior, whereas when it exceeds 10% by weight, the adhesion is improved However, since the viscosity increases too much and workability deteriorates, it is not preferable.
[68]
On the other hand, a conductive additive is added to improve the surface electrical conductivity and seam weldability of the steel sheet, and the conductive additive may include 0.3 to 7 wt% of a metal and 0.2 to 3 wt% of a surfactant. In other words, the weight ratio of the metal and the surfactant included in the conductive additive is preferably 3:2 to 7:3. If the content of the metal is less than 0.3%, it is difficult to secure the desired conductivity, and if it exceeds 7%, the conductivity is good, but it is not preferable because it impairs the adhesion of the coating film.
[69]
The metal is not particularly limited, but one or more selected from the group consisting of silver, aluminum, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, palladium, platinum, tin, tungsten and zinc may be used, It is preferable that the particle diameter is 10 nm - 900 nm. The smaller the size of the metal, the better the dispersion stability. When the size of the metal is more than 900 nm in particle diameter, dispersion stability is deteriorated, and roll coating workability is deteriorated.
[70]
On the other hand, the surfactant is a fatty acid alkali salt, fatty acid ammonium salt, alkyl sulfate salt, alkyl ether sulfate salt, alkyl phenol ethoxylate sodium salt, alkyl phenol ethoxylate ammonium salt, polyoxyethylene fatty acid ester and polyoxyethylene sorbitan fatty acid ester It may be at least one selected from the group consisting of.
[71]
In more detail, the fatty acid alkali salt and fatty acid ammonium salt may include a unit structure represented by the following formula (2). The chain type described below may be straight-chain or branched.
[72]
[Equation 2]
[73]

[74]
(In Formula 2, R' and R'' each independently mean a chain-type alkyl group having 5 to 15 carbon atoms.)
[75]
The alkyl sulfate salt may include a unit structure represented by the following formula (3).
[76]
[Equation 3]
[77]

[78]
(In Formula 3, R means a chain alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[79]
The alkyl ether sulfate salt may include a unit structure represented by the following formula (4).
[80]
[Equation 4]
[81]

[82]
(In Formula 4, R means a chain alkyl group having 1 to 10 carbon atoms, and n is an integer from 1 to 10.)
[83]
The polyoxyethylene fatty acid ester may include a unit structure represented by the following formula (5).
[84]
[Equation 5]
[85]

[86]
(In Formula 5, R denotes a chain-type alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[87]
The polyoxyethylene fatty acid ester may include a unit structure represented by the following formula (6).
[88]
[Equation 6]
[89]

[90]
(In Formula 6, R means a chain alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[91]
On the other hand, in addition to the above compounds, glycerin fatty acid ester, polyglycerin fatty acid ester, glyceryl ricinoleate, glyceryl stearate, glyceryl rosinate, raneth-5, raneth-10, raneth-15, lanolin, lautrimo At least one selected from among nium chloride, cetrimonium bromide, cetrimonium chloride, sodium isostearoyl lactate, sorbitan laurate, sorbitan stearate and sorbitan oleate may be used as the surfactant.
[92]
A conductive additive in the form of a dispersion may be prepared by dispersing the micelle compound formed of the metal and the surfactant together with a polymer resin or an oligomer compound in a high-speed bead mill. The polymer resin used may be urethane, epoxy, acryl, ester copolymer urethane polymer resin, or the like. In addition, the oligomer compound may be an oligomer of the polymer resin.
[93]
FIG. 2 schematically shows the high-speed bead mill used for manufacturing the conductive additive of the present invention and the flow of the dispersion liquid inside the high-speed bead mill. Referring to FIG. 2, the solution moves through the rotor filled with ceramic beads. While the metal and the bead mill collide, the nanoparticles are crushed and the polymer resin is dispersed. At this time, the higher the rotation speed of the rotor and the higher the input speed of the polymer solution, the greater the dispersion effect. In order to maximize the dispersion effect, it can be repeatedly added to the bead mill, and accordingly, the particle size becomes smaller and the dispersion solution is stabilized.
[94]
It is preferable that the remainder except for the above-mentioned components contain a solvent, and the solvent is not particularly limited, but water is preferably used in consideration of workability and environmental characteristics. The water means deionized water or distilled water.
[95]
According to another aspect of the present invention, a steel plate; a plating layer formed on at least one surface of the steel sheet; and a composite resin coating layer formed on the plating layer, wherein the composite resin coating layer is based on the total weight of the composite resin composition, 10 to 20% by weight of a polymer resin, 1 to 10% by weight of a curing agent, 1 to 10% by weight of an anticorrosion additive , 0.5 to 10% by weight of an adhesion promoter, and 0.5 to 10% by weight of a conductive additive; A composite resin-coated steel sheet for a fuel tank is provided, which includes a.
[96]
As described above, the steel sheet applicable to the present invention is not particularly limited, and may be a generally used cold-rolled steel sheet. In order to strengthen the corrosion resistance of such a cold-rolled steel sheet and apply it to a fuel tank, in the present invention, a Zn-X alloy hot-dip plated steel sheet, that is, a steel sheet in which a hot-dip plated layer made of a Zn-X alloy is formed on at least one surface of the steel sheet can be used. . Here, X means two or more elements selected from the group consisting of Al, Mg, Ni and Si.
[97]
The Zn-X alloy preferably contains 1 to 20 parts by weight of at least two elements selected from the group consisting of Al, Mg, Ni and Si based on 100 parts by weight of Zn. When it is less than 1 part by weight, the improvement of physical properties by the alloy cannot be obtained, and when it exceeds 20 parts by weight or more, the alloying ratio is increased to deteriorate operability as well as increase the cost.
[98]
It is preferable that the plating amount on one side of the plating layer is 10 to 60 g/m2, and when it is less than 10 g/m2, long-term corrosion resistance cannot be obtained, and when it exceeds 60 g/m2, there is a problem in that weldability deteriorates.
[99]
A composite resin coating layer is formed on the plating layer, and since the components and roles have been described above, detailed descriptions thereof will be omitted herein. By forming a composite resin coating layer on the zinc alloy-based plating layer. Corrosion resistance and conductivity are improved, and accordingly, it is possible to improve LME (Liquid Metal Embrittlement) problems that occur during elongation and welding according to the processing of steel sheet.
[100]
The thickness of the composite resin coating layer is preferably 0.1 ~ 1.5㎛. If the thickness is less than 0.1㎛, it is difficult to secure sufficient corrosion resistance and fuel resistance because the thickness of the coating film is too thin.
[101]
On the other hand, it is preferable that the adhesion amount of the composite resin coating layer is 0.1 to 2.0 g/m 2 . If it is less than 0.1 g/m 2 , it is difficult to secure corrosion resistance and fuel resistance, and if it is more than 2.0 g/m 2 , insulation increases and weldability deteriorates, which is not preferable.
[102]
According to another aspect of the present invention, the method comprising: forming a plating layer on at least one surface of a steel sheet; applying a composite resin composition on the plating layer; and curing the applied composite resin composition, wherein the composite resin composition contains 10 to 20% by weight of a polymer resin based on the total weight of the composite resin composition; 1 to 10% by weight of a curing agent; 1-10 wt% of anti-corrosion additive; Adhesion enhancer 0.5 to 10% by weight; 0.5-10 wt% of a conductive additive; And there is provided a method for manufacturing a composite resin-coated steel sheet for a fuel tank comprising the remaining solvent.
[103]
Since a method of preparing a steel sheet and forming a plating layer on the steel sheet may be performed by applying normal conditions, a detailed description thereof will be omitted.
[104]
The step of applying the composite resin composition on the plating layer may be performed using a dipping, roll coating or spray coating method, and the curing of the applied composite resin composition may be performed using hot air or induction heating. . The curing temperature is preferably in the range of 100 to 180 ℃ based on the steel plate temperature (PMT, Peak Metal Temperature), and when the temperature is less than 100 ℃, the reaction between the organic composition and the inorganic additive is insufficient, so corrosion resistance and fuel resistance difficult to obtain On the other hand, when the temperature exceeds 180° C., the crosslinking reaction of the curing agent is excessively increased, so that the coating film is hardened, and processability is deteriorated.
[105]
The composite resin-coated steel sheet of the present invention sequentially including the composite resin coating layer together with the plating layer has excellent corrosion resistance and corrosion resistance as well as excellent formability, so it is suitable as a material for a hybrid fuel tank requiring molding into a complex shape It will be said that there is an effect of applying it.
Modes for carrying out the invention
[106]
Hereinafter, the present invention will be described in more detail with reference to Examples. The following examples are provided to explain the present invention in more detail, and the present invention is not limited thereto.
[107]
1. Preparation of conductive additives and evaluation of dispersibility
[108]
production example
[109]
The type, particle size, and surfactant of the metal were added to the urethane polymer resin under the conditions shown in Table 1 below, and the metal and the surfactant were added in a weight ratio of 3:2, and a dispersion was prepared using a high-speed bead mill dispersing device, respectively. .
[110]
Comparative Preparation Examples 1 to 6
[111]
A dispersion was prepared using a conventional mechanical dispersion method rather than a high-speed bead mill dispersion device, and the components and conditions are as shown in Table 1.
[112]
Dispersibility Assessment
[113]
Dispersibility was evaluated in the following way. The dispersion prepared in the same manner as in Table 1 was put into a Turbiscan spectrometer, and the time it took until the transmittance increased by 10% or more was evaluated, and the results are shown in Table 1.
[114]
Excellent [◎] Time until the transmittance increases by 10% 2 hours or more
[115]
Normal [○] Time until transmittance increases by 10% 1 hour or more Within 2 hours
[116]
Insufficient [△] Time until the transmittance increases by 10% 0.5 hours or more Within 1 hour
[117]
Poor [X] Time to increase in transmittance by 10% less than 0.5 hours
[118]
[Table 1]
[119]
Referring to Table 1, the micellar compound composed of a conductive nano-metal and a surfactant is produced by the collision of the nano-metal with the bead mill as the solution moves through the rotor filled with ceramic beads of the bead mill disperser having the structure as shown in FIG. As the crushing and dispersion of the polymer resin are made, it is possible to effectively prepare a dispersion. As in Preparation Examples 1 to 14, the dispersion efficiency is high compared to the existing mechanical stirring method, so the time can be shortened, and the surface of the nanometal is effectively modified by the surfactant, so that precipitation or re-agglomeration in aqueous solution can be prevented. can confirm.
[120]
[121]
2. Manufacture of composite resin coated steel sheet and evaluation of physical properties
[122]
Form a hot-dip zinc alloy plating layer on a cold-rolled steel sheet, and 3 parts by weight of lithium polysilicate as an anticorrosion additive in 10% by weight of a urethane polymer (molecular weight 30000 to 50000, Tg 10°C) on the plating layer, conductive additive 2 according to Preparation Example 1 The composite resin composition prepared by using parts by weight, 2 parts by weight of the adhesion promoter having the structure of Formula 6, 2 parts by weight of a melamine-based curing agent, and the remainder of the solvent (water) was applied by a roll coating method. Thereafter, the steel sheet was cured and dried at 140 ° C., and then cooled with water to prepare a composite resin coated steel sheet having a dry film weight of 0.1 to 1.5 g/m 2 , and the specific conditions are as shown in Table 2 below.
[123]
In addition, it is shown in Table 3 after evaluating corrosion resistance, fuel resistance, seam weldability and workability under the following conditions.
[124]
Corrosion resistance evaluation
[125]
Corrosion resistance was evaluated by the complex salt spray method (Cyclic Corrosion Test, CCT). Salt spray (concentration of 5%, spray pressure of 1kg/cm2 at 35°C) for 5 hours at 95% relative humidity condition, dry at 30% relative humidity and 70°C for 2 hours, then 95% relative humidity, temperature After repeating 50 cycles of 1 cycle of treatment at 50° C. for 3 hours, the area of ​​occurrence of red rust on the surface of the steel sheet was evaluated.
[126]
◎: Corrosion area is 0%
[127]
○: Corrosion area less than 5%
[128]
△ : 5~30% of corrosion area
[129]
×: more than 30% of the corrosion area
[130]
Fuel resistance evaluation
[131]
The fuel resistance evaluation was evaluated by the accelerated fuel resistance test of diesel, deteriorated diesel (H2O 5%, formic acid 100ppm included) and biodiesel 5% composition (BD5). For the evaluation specimen, after processing the cup as above (Blank size: 115×115 mm; Cup size, Punch diameter 50mm, Drawing height 30mm, Punch R = Die R = 6R), put fuel into the Cup and use a fluorine O-ring and a glass plate. It was evaluated by covering it and fixing it. In the diesel fuel composition, 30 ml of diesel fuel was put into a cup, and the corrosion state of the steel sheet was evaluated after leaving it for 8 weeks while shaking at a rate of 60 cycles per minute at 60 °C, respectively. The evaluation criteria are as follows.
[132]
◎: Corrosion area is 0%
[133]
○: Corrosion area less than 5%
[134]
△ : 5~30% of corrosion area
[135]
×: more than 30% of the corrosion area
[136]
Seam weldability evaluation
[137]
Seam weldability was evaluated using Ironman (Inverter DC Seam welding machine) to maintain constant strength without spatter at 4kN of pressing force, 6mpm of welding speed, 33ms of energization time, and 10ms of rest time. The evaluation criteria were evaluated by measuring the length of LME (Liquid Metal Embrittlement, Molten Metal Embrittlement) through the grain boundary cross-sectional structure analysis of the weld zone.
[138]
◎: less than 10mm
[139]
○: 10mm or more and less than 20mm
[140]
△: 20mm or more
[141]
Processability evaluation
[142]
The workability was evaluated by limiting dome height test using a thin plate flat extension tester. Experimental conditions were evaluated from the molding height after molding until fracture with a punch diameter of 100 mm, a blank holding force (BHF) of 20 tons, and a punch speed of 200 mm/min without lubrication.
[143]
◎: 500mm or more
[144]
○ : 30mm or more and 500mm or less
[145]
△: 300mm or less
[146]
[Table 2]
[147]
[Table 3]
[148]
Referring to Table 3, the composite coated steel sheet coated on the Zn-aAl-bMg hot-dip galvanized steel sheet in Examples 1 to 18 has a composite coating composition of 0.5 to 1.5 g/m 2 or an additional conductive material of 0.05 to 0.15 g/m 2 In the case of coating, it was found that processability and fuel resistance were excellent. However, in the case of a=2.8% and b=3.0% composition, cracks occurred due to LME characteristics after welding.
[149]
On the other hand, the Zn electroplated steel sheet and the Zn-Fe alloy plated steel sheet of Comparative Examples 1 to 8 were relatively weak in corrosion resistance and fuel resistance, and the Al-Si steel sheet had poor corrosion resistance and weldability in the machining part, and Zn-aAl-bMg In the case of (a=6.0%, b=3.0%), it was found that the LME properties of the welded part were very bad.
[150]
Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible within the scope without departing from the technical spirit of the present invention described in the claims. It will be apparent to those of ordinary skill in the art.
Claims
[Claim 1]
Based on the total weight of the composite resin composition, 10 to 20% by weight of the polymer resin; 1 to 10% by weight of a curing agent; 1-10 wt% of anti-corrosion additive; Adhesion enhancer 0.5 to 10% by weight; 0.5-10 wt% of a conductive additive; And a composite resin composition for a fuel tank steel sheet comprising the remainder of the solvent.
[Claim 2]
The composite resin composition for a fuel tank steel sheet according to claim 1, wherein the steel sheet is a Zn-X alloy hot-dip plated steel sheet (where X is at least two elements selected from the group consisting of Al, Mg, Ni and Si. do.).
[Claim 3]
The composite resin composition for a fuel tank steel sheet according to claim 2, wherein the Zn-X alloy contains 1 to 20 parts by weight of element X based on 100 parts by weight of Zn.
[Claim 4]
The composite resin composition for a fuel tank steel sheet according to claim 1, wherein the adhesion promoter comprises a unit structure represented by the following formula (1). [Formula 1] (In Formula 1, R is vinyl (vinyl), 2- (3,4-epoxycyclohexyl) ethyl (2- (3,4-epoxycyclohexyl) ethyl), 3-glycidoxypropyl (3-glycidoxypropyl ), p-styrenyl (p-styrenyl), 3-methacryloxypropyl (3-methacryloxypropyl), 3-acryloxypropyl (3-acryloxypropyl), N-2- (aminoethyl) -3-aminopropyl (N -2-(aminoethyl)-3-aminopropyl), 3-aminopropyl (3-aminopropyl), and N-phenyl-3-aminopropyl (N-phenyl-3-aminopropyl)
[Claim 5]
The composite resin composition for a fuel tank steel sheet according to claim 1, wherein the conductive additive comprises 0.3 to 7% by weight of a metal and 0.2 to 3% by weight of a surfactant.
[Claim 6]
The fuel tank according to claim 5, wherein the metal is at least one selected from the group consisting of silver, aluminum, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, palladium, platinum, tin, tungsten and zinc. Composite resin composition for steel sheet.
[Claim 7]
The composite resin composition for a fuel tank steel sheet according to claim 5, wherein the metal has an average particle diameter of 10 to 900 nm.
[Claim 8]
6. The method according to claim 5, wherein the surfactant is a fatty acid alkali salt, a fatty acid ammonium salt, an alkyl sulfate salt, an alkyl ether sulfate salt, an alkyl phenolethoxylate sodium salt, an alkyl phenolethoxylate ammonium salt, a polyoxyethylene fatty acid ester and a polyoxyethylene A composite resin composition for a fuel tank steel sheet, characterized in that at least one selected from the group consisting of sorbitan fatty acid esters.
[Claim 9]
The composite resin composition for a fuel tank steel sheet according to claim 8, wherein the fatty acid alkali salt and fatty acid ammonium salt have a unit structure represented by the following formula (2). [Formula 2] (In Formula 2, R′ and R′′ each independently mean a chain alkyl group having 5 to 15 carbon atoms.)
[Claim 10]
The composite resin composition for a fuel tank steel sheet according to claim 8, wherein the alkyl sulfate salt has a unit structure represented by the following formula (3). [Formula 3] (In Formula 3, R means a chain alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[Claim 11]
The composite resin composition for a fuel tank steel sheet according to claim 8, wherein the alkyl ether sulfate salt has a unit structure represented by the following formula (4). [Formula 4] (In Formula 4, R means a chain-type alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[Claim 12]
The composite resin composition for a fuel tank steel sheet according to claim 8, wherein the polyoxyethylene fatty acid ester has a unit structure represented by the following formula (5). [Formula 5] (In Formula 5, R means a chain-type alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[Claim 13]
The composite resin composition for a fuel tank steel sheet according to claim 8, wherein the polyoxyethylene fatty acid ester has a unit structure represented by the following formula (6). [Formula 6] (In Formula 6, R means a chain alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10.)
[Claim 14]
grater; a plating layer formed on at least one surface of the steel sheet; and a composite resin coating layer formed on the plating layer, wherein the composite resin coating layer is based on the total weight of the composite resin composition, 10 to 20% by weight of a polymer resin, 1 to 10% by weight of a curing agent, 1 to 10% by weight of an anticorrosion additive , 0.5 to 10% by weight of an adhesion promoter, and 0.5 to 10% by weight of a conductive additive; Which includes, a composite resin coated steel sheet for a fuel tank.
[Claim 15]
[Claim 15] The composite resin-coated steel sheet for a fuel tank according to claim 14, wherein the plating layer contains 1 to 20 parts by weight of element X based on 100 parts by weight of Zn (where X is made of Al, Mg, Ni and Si). Refers to two or more elements selected from the group).
[Claim 16]
[Claim 15] The composite resin-coated steel sheet for fuel tanks according to claim 14, wherein the plating amount on one side of the plating layer is 10 to 60 g/m2.
[Claim 17]
The composite resin-coated steel sheet for fuel tanks according to claim 14, wherein the composite resin coating layer has a thickness of 0.1 to 1.5 μm.
[Claim 18]
15. The composite resin-coated steel sheet for fuel tanks according to claim 14, wherein the adhesion amount of the composite resin coating layer is 0.1 to 2.0 g/m 2 .
[Claim 19]
forming a plating layer on at least one surface of the steel sheet; applying a composite resin composition on the plating layer; and curing the applied composite resin composition, wherein the composite resin composition contains 10 to 20% by weight of a polymer resin based on the total weight of the composite resin composition; 1 to 10% by weight of a curing agent; 1-10 wt% of anti-corrosion additive; Adhesion enhancer 0.5 to 10% by weight; 0.5-10 wt% of a conductive additive; And a method for manufacturing a composite resin-coated steel sheet for a fuel tank comprising the remaining solvent.
[Claim 20]
The method of claim 19, wherein the plating layer contains 1 to 20 parts by weight of element X based on 100 parts by weight of Zn (wherein X is Al, Mg, Ni and It means two or more elements selected from the group consisting of Si).
[Claim 21]
The method of claim 19, wherein the conductive additive is prepared by dispersing a mixture containing 0.3 to 7 wt% of a metal and 0.2 to 3 wt% of a surfactant using a high-speed bead mill.
[Claim 22]
The method of claim 19, wherein the hardening is performed at 100 to 180°C.