Composite resin composition for steel plate for fuel tank, composite resin-coated steel plate using same, and manufacturing method therefor

1. A composite resin composition for steel plates for a fuel tank, comprising:

30 to 65% by weight of a polymer resin;

1 to 15% by weight of a curing agent;

2 to 20% by weight of a corrosion-resistant additive;

1 to 15% by weight of an adhesion promoting agent comprising a polyphosphazene polymer compound; and

a residual solvent.

2. The composite resin composition according to claim 1 , wherein the polyphosphazene polymer compound has a number average molecular weight of 5,000 to 50,000, and has one or more substitution functional groups of alkyl, substituted alkyl, aryl, and substituted aryl.

3. The composite resin composition according to claim 1 , wherein

the polymer resin is one or more selected from urethane polymer, acrylic polymer, ester polymer and epoxy-urethane copolymer, wherein the polymer resin has a number average molecular weight of 5,000 to 50,000 and a Tg of 10 to 50° C.

4. The composite resin composition according to claim 1 , wherein the curing agent is one or more of a melamine-based curing agent, an aziridine curing agent, and an isocyanate curing agent.

5. The composite resin composition according to claim 4 , wherein the melamine-based curing agent is one or more of melamine, butoxymethyl melamine, hexamethoxymethyl melamine and trimethoxymethyl melamine.

6. The composite resin composition according to claim 1 , wherein the corrosion-resistant additive is a mixture of a silicate compound and a titanium compound,

wherein the silicate compound and the titanium compound are included in a weight ratio of 0.5:1 to 4:1.

7. The composite resin composition according to claim 6 , wherein the silicate compound is one or more of lithium polysilicate, sodium polysilicate, potassium polysilicate, and colloidal silica, and

the titanium compound is one or more of titanium carbonate, isopropyl ditriethanol aminotitanate, titanium lactic acid chelate, and titanium acetylacetonate.

8. A composite resin-coated steel plate for a fuel tank, comprising:

a steel plate;

a plated layer formed on at least one surface of the steel plate; and

a composite resin-coated layer formed on the plated layer,

wherein the composite resin-coated layer comprises 40 to 85% by weight of a polymer resin, 3 to 20% by weight of a curing agent, 5 to 25% by weight of a corrosion-resistant additive, and 3 to 20% by weight of an adhesion promoting agent comprising a polyphosphazene polymer compound,

wherein the steel plate has a tensile strength of 800 MPa or more and an elongation of 35% or more.

9. The composite resin-coated steel plate according to claim 8 , wherein the polyphosphazene polymer compound has a number average molecular weight of 5,000 to 50,000, and has one or more substitution functional groups of alkyl, substituted alkyl, aryl, and substituted aryl.

10. The composite resin-coated steel plate according to claim 8 , wherein the composite resin-coated layer is formed to a thickness of 0.1 to 2.0 μm.

11. The composite resin-coated steel plate according to claim 8 , wherein the polymer resin is one or more selected from urethane polymer, acrylic polymer, ester polymer and epoxy-urethane copolymer, wherein the polymer resin has a number average molecular weight of 5,000 to 50,000 and a Tg of 10 to 50° C.

12. The composite resin-coated steel plate according to claim 8 , wherein the curing agent is one or more of a melamine-based curing agent, an aziridine curing agent, and an isocyanate curing agent.

13. The composite resin-coated steel plate according to claim 8 , wherein the corrosion-resistant additive comprises a silicate compound and a titanium compound in a weight ratio of 0.5:1 to 4:1.

14. The composite resin-coated steel plate according to claim 13 , wherein the composite resin-coated layer has a weight ratio {([Si]+[Ti])/[P]} between Si, Ti, and P of 0.5 to 1.5,

wherein the [Si] is weight derived from the corrosion-resistant additive including the silicate compound, the [Ti] is weight derived from the corrosion-resistant additive including the titanium compound, and the [P] is weight derived from the adhesion promoting agent including the polyphosphazene polymer compound.

15. The composite resin-coated steel plate according to claim 13 , wherein the silicate compound is one or more of lithium polysilicate, sodium polysilicate, potassium polysilicate, and colloidal silica, and

the titanium compound is one or more of titanium carbonate, isopropyl ditriethanol aminotitanate, titanium lactic acid chelate, and titanium acetylacetonate.

16. The composite resin-coated steel plate according to claim 8 , wherein the steel plate comprises, by weight %, 0.2 to 1.0% of carbon (C), 12 to 20% of manganese (Mn), 0.5 to 2.5% of solid solution aluminum (S—Al), balance Fe, and other unavoidable impurities.

17. The composite resin-coated steel plate according to claim 8 ,

wherein the plated layer is an electroplated layer or a hot-dip plated layer,

wherein the electroplated layer is a zinc plated layer or a zinc-nickel alloy plated layer, and

the hot-dip plated layer is one of a hot-dip zinc plated layer, an alloyed hot-dip zinc plated layer, a zinc-aluminum-magnesium alloy plated layer, and an aluminum-silicon alloy plated layer.

18. The composite resin-coated steel plate according to claim 17 , wherein the electroplated layer is formed in a single surface adhesion amount of 5 to 40 g/m 2 , and

the hot-dip plated layer is formed in a single surface adhesion amount of 20 to 60 g/m 2 .

19. A manufacturing method for a composite resin-coated steel plate, comprising:

preparing a steel plate;

forming a plated layer on at least one surface of the steel plate;

applying a composite resin composition for a fuel tank steel plate to an upper portion of the plated layer; and

drying the applied composite resin composition at a temperature of 120 to 200° C.,

wherein the composite resin composition for a fuel tank steel plate comprises

30 to 65% by weight of a polymer resin;

1 to 15% by weight of a curing agent;

2 to 20% by weight of a corrosion-resistant additive;

1 to 15% by weight of an adhesion promoting agent comprising a polyphosphazene polymer compound; and

a residual solvent.

20. The method according to claim 19 , wherein the steel plate comprises, by weight, 0.2 to 1.0% of carbon (C), 12 to 20% of manganese (Mn), 0.5 to 2.5% of solid solution aluminum (S—Al), residual iron (Fe), and other unavoidable impurities, and is a high manganese cold-rolled steel plate having a tensile strength of 800 MPa or more and an elongation of 35% or more.