KR101482182B1 - Manufacturing method for steel pipe with polyurethan-imide resin coating layer - Google Patents

Abstract

The present invention relates to a method for manufacturing a steel pipe having a polyurethane-imide resin coating layer, and more specifically, to a method for manufacturing a steel pipe having a polyurethane-imide resin coating layer, which mixes a polyurethane-imide resin and a hardener by a static mixer and sprays the same on the steel pipe in a fan shape spray method. The polyurethane-imide resin and the hardener mixed by a static mixer module used in the manufacturing method of the present invention uniformly form the coating layer as mixing efficiency is increased, thereby producing a high quality steel pipe. Specially, little delamination of the coating layer generated when perforating occurs, and a steel pipe having excellent properties such as thermal resistance, chemical resistance, high stiffness, and salt water resistance can be manufactured.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a steel pipe having a polyurethane imide resin coating layer,

The present invention relates to a method for producing a steel pipe having a polyurethane imide resin coating layer. More particularly, the present invention relates to a method for producing a steel pipe having a polyurethane imide resin coating layer, which comprises mixing a polyurethane imide resin and a curing agent in a static mixer capable of enhancing mixing efficiency, ≪ / RTI >

In general, pipes are used for various types of prefabricated structures in various applications. In recent years, metal pipes, pipes coated with liquid paint, or coated pipes coated with synthetic resin have been widely used on the outer peripheral surface of pipes . In particular, the synthetic resin coated pipe can be provided with an exquisite appearance by processing various colors on its outer surface depending on the color of the synthetic resin to be coated.

The steel pipe in the pipe is coated on the inner surface and the outer surface to prevent corrosion by the fluid. At this time, the coating material used for coating the steel pipe is a liquid resin or a resin powder. The method of coating the steel pipe using powder is to pre-treat the surface of the steel pipe so that the paint is well adhered, and preheat the steel pipe to about 200 to 230 ° C using a heating device. Thereafter, the powder paint is sprayed to the preheated steel pipe with a certain thickness using spray. Then, the powder coating is melted and cured by the heat of the steel pipe to form a coating film. The coating film prevents contact between the liquid and the metal material, thereby preventing corrosion and maintaining the state of the steel pipe.

However, when the powder is used as described above, the efficiency of mixing with the curing agent for curing the powder coating material is relatively low, so that there is a problem that the coated steel pipe peels off during welding or perforation. In addition, steel pipes are mainly used for pipes for water supply, sewerage, gas and petrochemical piping, industrial water, and other fluid transportation. Therefore, a method for manufacturing steel pipes excellent in heat resistance, flame resistance and chemical resistance is highly demanded.

Korean Patent Laid-Open Publication No. 2006-0020076 discloses a liquid polyurea resin coating method and a technique relating to a coated steel pipe using the same, and Korean Patent No. 1282928 discloses a steel pipe manufacturing apparatus having an epoxy resin coating layer containing tourmaline Technology has been disclosed, but the above-mentioned demands are still insufficient to solve the above-mentioned problems.

Particularly, in the process of manufacturing the coated steel pipe, the lowering of the mixing rate in the mixing process of the fluid may cause the reaction rate to be lower than the required value to terminate the reaction before the completion of the reaction, and may cause unnecessary reaction.

 Mixing devices range from a mechanical agitator to a static mixer mounted in a pipe or duct without moving parts.

The static mixer is installed in a material transfer line of a food factory, a medicine factory, a chemical factory, etc., and is used for the purpose of mixing and mixing various raw materials, or it is installed in a heat exchanger so that the fluid continuously contacts the inner wall of the tube So as to increase the heat exchange efficiency. Such a static mixer began to be developed in the 1950s, and after the commercial use of the mixer developed by Kenics in the late 1960s, more than 30 kinds of mixers were developed, but there are not many kinds actually used in the industrial field.

Currently the most widely used static mixers are Kenics and Sulzer. A static mixer, which is an in-line structure, is composed of a series of mixing elements fixed in the mixing tube without moving parts in the system component itself, and continuously flows when the fluid to be mixed passes through the pipeline Splitting, redirecting, and recombining are repeated and used in a continuous mixing operation of the fluid with a mixing device. Static mixers have no moving parts compared to mechanical stirrers, so they can be installed in pipelines without rotating elements such as shafts or bearings or sealing devices. Also, the heat transfer area per unit volume is large, and it is suitable for mixing of continuous process and high viscosity liquid, and it is possible to equalize the residence time distribution in the mixer of the fluid to be mixed and to facilitate the process control, . Therefore, the static mixer is widely applied in the industrial field.

Since the mixing ratio of the fluid is the most important parameter to evaluate the performance of the static mixer, most of the studies are located inside the static mixer and are biased toward the mixing member to mix the fluid. A conventional static mixer, Kenics static mixer, is shown in Fig. As shown in FIG. 1, the mixing member (c) is composed of a plurality of unit panels (d) twisted by 180 degrees continuously joined back and forth so as to repeat the process of fluid division, redirection, Mix continuously.

However, as shown in FIG. 2 and FIG. 3, when the fluid is moved along the internal flow path, the fluid is divided, reoriented, and recombined in the center portion e of the flow path by the mixing member c, B are formed to smoothly mix the fluid.

However, there is a problem in that the fluid is not mixed well at the edge portion (f) of the flow path. The mixing member (c) is inserted into the housing (b) of the static mixer, and a minute gap is formed between the mixing member (c) and the inner peripheral surface of the housing (b). The laminar flow A is formed along the inner circumferential surface of the housing b at the edge portion f of the flow path that contacts the inner circumferential surface of the housing b. The flow of the laminar flow A continues to move along the inner circumferential surface of the housing b and is discharged to the outside of the housing, thereby lowering the mixing efficiency of the fluid as a whole.

Korean Patent No. 0862897 discloses a technique for manufacturing a static mixer element, Korean Patent Laid-Open Publication No. 2013-0118456 discloses a technique relating to an ozone contact dissolution apparatus using a static mixer, 2002-0097299 discloses a method and an apparatus for producing a distilled water using a static mixer and an ultrasonic wave. However, the present invention relates to a static mixer for improving fluid mixing efficiency in a flow path by reducing laminar flow formed along an edge of a flow path No technology has been reported.

The present invention provides a method for manufacturing a steel pipe having a polyurethane imide resin coating layer by reducing the laminar flow formed along the edge of the flow path to increase the mixing efficiency of the fluid in the flow path, A polyurethane imide resin and a curing agent were mixed with each other using a static mixer module capable of being sprayed on a steel pipe to be coated, thereby completing the present invention.

In order to achieve the above object, the present invention provides a method for producing a polyurethane imide resin composition, which comprises mixing a polyurethane imide resin and a curing agent using a coating apparatus comprising a static mixer module (M10) and a spraying module (S10) And spraying a polyurethane imide resin mixed with the curing agent onto the inner or outer wall of the steel pipe. The present invention also provides a method of manufacturing a steel pipe having a polyurethane imide resin coating layer.

The present invention relates to a process for producing a steel pipe having a polyurethane imide resin coating layer, and more particularly, to a process for producing a polyurethane imide resin coating layer, Wherein the polyurethane imide resin coating layer is formed on the steel pipe by spraying using an improved static mixer module to form a polyurethane imide resin coating layer will be.

The method for producing a steel pipe having a polyurethane imide resin coating layer of the present invention is characterized in that the mixing efficiency is improved by using a static mixer module (M10) which mixes the base material and the curing agent as a raw material of the polyurethane imide resin so as to be uniformly mixed, As well as a method for producing a steel pipe having a polyurethane imide resin coating layer which is superior in heat resistance.

The steel pipe having the polyurethane imide resin coating layer according to the production method of the present invention is effective not only for preventing peeling of the coated polyurethane imide resin but also for producing a steel pipe having excellent heat resistance, chemical resistance and flame resistance There is an advantage to be able to.

1 is a partially cutaway perspective view showing a conventional static mixer.
2 is a cross-sectional view of Fig.
FIG. 3 is a cross-sectional view showing regions forming different fluid flows in the static mixer of FIG. 1. FIG.
FIG. 4 is a perspective view illustrating an essential portion of a static mixer module M10 according to an embodiment of the present invention.
5 is a cross-sectional view of the static mixer module M10 to which FIG. 4 is applied.
6 is a cross-sectional view illustrating an essential portion of a static mixer module M10 according to another embodiment of the present invention.
FIG. 7 is a cross-sectional view illustrating an essential part of a static mixer module M10 according to still another embodiment of the present invention.
FIG. 8 is a cross-sectional view illustrating an essential portion of a static mixer module M10 according to still another embodiment of the present invention.
Fig. 9 is a perspective view showing an example of a recess applied to Fig. 8. Fig.
10 is a front view showing the collision member 60 of Fig.
FIG. 11 is a cross-sectional view illustrating an essential part of a static mixer module M10 according to still another embodiment of the present invention.
FIG. 12 is a cross-sectional view illustrating an essential part of a static mixer module M10 according to still another embodiment of the present invention.
FIG. 13 is a cross-sectional view illustrating an essential part of a static mixer module M10 according to still another embodiment of the present invention.
14 is a perspective view illustrating the injection module S10 according to an embodiment of the present invention. S01 is a connection part to the static mixer module, S02 is an injection control part, and S03 is a jet micro outlet.
15 is a sectional view showing a coating apparatus including a static mixer module M10 and a spray module S10 according to an embodiment of the present invention.

A method for manufacturing a steel pipe having a coating layer,

Mixing a polyurethane imide resin and a curing agent using a coating apparatus including a static mixer module and a spray module capable of enhancing mixing efficiency; And

And spraying the polyurethane imide resin mixed with the curing agent onto the inner or outer wall of the steel pipe. The present invention also provides a method of manufacturing a steel pipe having the polyurethane imide resin coating layer.

The present invention is characterized by using a coating device equipped with a static mixer module (M10) and a spray module (M2). Hereinafter, the coatings used in the method of manufacturing a steel pipe having a polyurethane imide resin coating layer Device.

First, a static mixer module M10 according to an embodiment of the present invention includes a housing 15, a mixing member 5, and a laminar flow reducing means 20 (see FIGS. 4 and 5).

The housing 15 has a pipe structure in which a circular flow path 17 is formed and a fluid can pass through the flow path 17 formed in the housing 15 and a fluid And the like.

The mixing member 5 is the same as the conventional technique shown in FIG. 1, and the mixing member 5 is a space for mixing at least two fluids that are installed inside the housing 15 and pass through the flow path 17 , The mixing member 5 is repeatedly combined with a plurality of unit panels 7 twisted at 180 ° so as to divide, redirect, and recombine the fluid, thereby continuously mixing the fluid passing through the flow path 17 will be. The mixing member 5 of the present invention does not exclude that it can be formed in various lengths by adjusting the number of the unit panels 7. [

The mixing member 5 is inserted into the housing 15 and installed in the flow path 17. In the illustrated example, the two mixing members 5 are arranged inside the housing 15 by being separated from each other by a predetermined distance in the front and rear directions. Alternatively, the two mixing members 5 may be interconnected by a connecting bar.

The laminar flow reduction means 20 is for reducing the laminar flow formed along the edge of the flow path 17 and may be provided with an interference fence 25 as an example of the laminar flow reduction means 20 of the present invention. The interference fringe 25 protrudes from the inner circumferential surface of the housing 15 toward the center of the flow path 17 and the interference fringe 25 is formed in a circular shape along the circumference of the inner circumferential surface of the housing 15. In the illustrated example, the interference fringe 25 is provided at one portion of the housing 15, but two or more of the interference fringes 25 may be provided at regular intervals. The preferred interference fringe 25 is formed to be inclined in the flow direction of the fluid. That is, it is preferable that the interference fringe 25 has a shape in which the cross-sectional area becomes gradually narrower toward the exit of the housing 15 from the entrance of the housing 15.

The interference fringe 25 is formed to protrude from the inner circumferential surface of the housing 15 to reduce the laminar flow formed along the inner circumferential surface of the housing 15. That is, the interference fingers 25 interfere with the flow of the fluid flowing adjacent to the inner circumferential surface of the housing 15, thereby changing the flow direction of the fluid, thereby making the fluid flow turbulent and increasing the overall fluid mixing efficiency.

The laminar flow reduction means 20 according to another embodiment of the present invention includes an enlarged diameter portion 30 formed at one portion of the housing 15 to temporarily enlarge the area of the flow passage 17.

Referring to FIG. 6, an enlarged diameter portion 30 is provided at one portion of the housing 15 so that the flow path area is widened. The enlarged diameter portion 30 is formed in a direction in which the diameter of the housing 15 is expanded to the outside. The enlarged diameter portion (30) enlarges the cross-sectional area of the enlarged flow passage (35) formed inside the housing (15).

The enlarged diameter portion 30 changes the flow of the fluid passing through the flow path 17 to increase the mixing efficiency. That is, the flow of fluid flowing adjacent to the inner circumferential surface of the housing 15 generates a vortex at the enlarged diameter portion 30, thereby reducing the laminar flow formed at the edge of the flow passage 17. The enlarged diameter portion 30 may be formed in the housing 15 at one or a plurality of intervals.

The laminar flow reduction means 20 according to another embodiment of the present invention includes a reduced diameter portion 40 formed on a part of the housing 15 to temporarily reduce the area of the flow passage 17. Referring to FIG. 7, a reduced diameter portion 40 is provided at one portion of the housing 15 to narrow the flow path 17 area. The reduced diameter portion 40 may be formed by enlarging the diameter of a portion of the housing 15. In the illustrated example, the reduced diameter portion 40 is formed in a protruding shape inward of the housing 15. The reduced diameter portion (40) forms a reduced flow path (45) inside the housing (15) where the cross sectional area becomes narrower.

The reduced diameter portion 40 changes the flow of the fluid passing through the flow path 17 to increase the mixing efficiency. The reduced diameter portion 40 functions to reduce the laminar flow formed at the edge of the flow path 17 by generating a vortex at the reduced diameter portion 40. The reduced diameter portion 40 may be formed in the housing 15, Can be formed.

The laminar flow reduction means (20) is installed inside the housing (15). For example, between the two mixing members 5 (see Figs. 8 to 10). The laminar flow reduction means 20 shown in the figures collides with the fluid passing through the converging member 50 and the converging member 50 provided inside the housing 15 to narrow the flow of the fluid passing through the mixing member 5, And a collision member (60) for dispersing the collision member (60).

 The converging member 50 includes a partition wall 51 formed to block the flow path 17 and having a converging hole 53 penetrating in the forward and backward directions and a partition wall 51 protruding from the rear surface of the partition wall 51, And a guide pipe 55 connected to the guide pipe 55.

The partition wall 51 is formed in a circular shape and is inserted into the housing 15 so as to intercept the flow path 17. The partition wall 51 is provided so as to be in close contact with the inner circumferential surface of the housing 15 so that fluid can not flow between the outer circumferential surface of the partition wall 51 and the inner circumferential surface of the housing 15. [ A circular converging hole 53 is formed at the center of the partition wall 51, and the converging hole 53 is formed to pass through the front surface from the front surface.

The guide tube 55 is formed to protrude from the rear surface of the partition wall 51 and guides the flow of the fluid passing through the converging hole 53 of the partition wall 51 in the direction of the collision groove 63 to be described later . The guide tube 55 has a hollow structure in which the inside is hollow, and the inner hollow space of the guide tube 55 is connected to the converging hole 53. Therefore, the fluid introduced into the converging hole 53 of the partition wall 51 moves backward to the partition wall 51 through the guide pipe 55.

In the illustrated example, the outer circumferential surface of the guide tube 55 is provided with the engaging portion 57 protruding outward. This is to prevent the guide tube 55 from being inserted beyond a predetermined depth when the guide tube 55 is inserted into the collision groove 63 to be described later.

The collision member 60 collides with the fluid discharged through the outlet of the guide pipe 55 to disperse and mix the fluid. The collision member 60 includes a body 61 provided to block the flow path 17 of the housing 15 and a collision groove 63 formed in the body 61 and in which the fluid passing through the guide pipe 55 collides And a plurality of dispersion passages 65 formed in the body 61 in the front and rear direction and arranged in the periphery of the impact grooves 63.

The body 61 has a circular shape and is inserted into the housing 15 to block the flow path 17. A body 61 is installed so that the outer circumferential surface of the body 61 is in close contact with the inner circumferential surface of the housing 15 so that fluid can not flow between the outer circumferential surface of the body 61 and the inner circumferential surface of the housing 15.

The impingement grooves 63 are formed on the guide pipe 55 in correspondence with the end portions thereof. Therefore, the impact groove 63 is formed at the center of the body 61. The converging member 50 and the impact member 60 are engaged with each other in such a manner that the end of the guide pipe 55 is inserted into the impact groove 63. [ The impact groove 63 is formed at a predetermined depth from the front surface of the body 61 in the rear direction. The diameter of the impingement groove 63 is larger than the outer diameter of the guide tube 55 and smaller than the outer diameter of the engaging portion 57. Therefore, when the end portion of the guide tube 55 is inserted into the impact groove 63, the guide tube 55 is prevented from being inserted by the engagement portion 57 beyond a predetermined depth.

A plurality of the dispersion passages (65) are provided around the impact groove (63). The dispersion passageway (65) is formed through the front surface of the body (61) in the rear direction. The fluid is dispersed and moved by a plurality of flows by the dispersion passage.

A connecting groove 67 connecting the impingement groove 63 and the dispersion passage 65 is formed on the front surface of the body 61. The connection groove 67 is formed to extend from the front surface of the body 61 to a certain depth in the rear direction. The connecting groove 67 is formed so as not to be deeper than the impact groove 63 and serves as a channel connecting the impact groove 63 and the dispersion passage 65.

The converging member 50 and the impingement member 60 may be installed at one side of the housing 15 or at two or more portions at regular intervals.

By passing the fluid through the converging member (50) into the converging hole (53), the flow of fluid can be converged into a narrow passage. Further, the fluid is collided with the collision member 60 and then dispersed into the plurality of dispersion passages 65. As described above, since the fluid primarily mixed while passing through the mixing member 5 is mixed again through the convergence and dispersion process, the laminar flow can be reduced and the mixing efficiency can be greatly improved.

The fluid having passed through the collision member (60) passes through the mixing member (5) again and is discharged through the outlet of the housing (15).

On the other hand, as shown in FIG. 11, the interference member 70 may be provided in the impact groove 63. In this case, the interference member (70) flows in the collision groove (63) while colliding with the fluid introduced into the collision groove (63). The flowing interfering member 70 may interfere with the flow of the fluid while colliding with the fluid to improve the mixing efficiency of the fluid. In the illustrated example, the interference member 70 is spherical. In order to prevent the interference member 70 from flowing out into the convergence hole 53 of the gateway pipe, the interference member 70 may be formed to have a size larger than the size of the convergence hole 53, The network can be installed. 12 shows a state in which the interference member 70 can be fixed in the impact groove 63 and the spring structure is applied to the flowing interference member 70. [ In addition to the spherical shape and the spring shape, various shapes such as a cylindrical shape, a polygonal shape, and a pipe shape can be applied to the interference member 70.

In addition, a spherical interference member 70 or a spring-shaped interference member 70 can be fixed in the impact groove 63.

Fig. 13 shows an example in which a ring-shaped interference member 70 is provided in the collision groove 63. Fig. In this case, a large number of interference members (70) are installed at regular intervals from the entrance of the collision groove (63).

The injection module S10 according to an embodiment of the present invention includes a connection part S01 with a static mixer module; An injection control unit S02 and a fine discharge port S03 (see Fig. 14).

The nozzle control unit may be configured such that the pattern of the nozzles to be ejected is one selected from a vortex chamber type, a deflection type, a spiral type, a circular type, a tapered rim type, and an entire fan type. . In the case of using a fan-shaped nozzle pattern, the sprayed particles are not formed largely, and the sprayed portion in the form of dust can be minimized.

And a high-pressure impingement mixing method through the injection micro-discharge port. In this case, the temperature and the pressure are adjusted as needed without limitations.

In addition, when the nozzle hole is clogged by applying a switch-tip (tread-tip) back-tip technique, the injection micro-discharge port is rotated in the opposite direction to remove foreign matter Function.

The thickness of the coating layer formed by spraying is not limited, but is preferably 0.1 to 10,000 占 퐉, more preferably 50 to 1,000 占 퐉.

The polyurethane imide resin of the present invention is preferably a method in which imidization is directly carried out by desorption of CO ₂ by a one-step reaction between diisocyanate and dianhydride, but the present invention is not limited thereto, and a suitable amount of diisocyanate, dianhydride, A method of synthesizing poly (urethane-imide) by each simultaneous reaction, or a method of synthesizing poly (urethane-imide) by excessively reacting an excess of diisocyanate with an appropriate amount of polyol to prepare a -NCO (isocyanate group) -type urethane and then reacting a terminal diisocyanate group and dianhydride (Urethane-imide) may be synthesized by a reaction between the poly (urethane-imide).

Preferred diisocyanates that can be used in the present invention can be represented by the following formula (1)

(1)

(One)

(In the formula _(1), R 1 is

More preferred diisocyanates include diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,1'-methylenebis (4-isocyanatecyclohexane), 1,3-bis (isocyanatemethyl) benzene, 1,3-bis (isocyanatomethyl) cyclohexane, but is not limited thereto.

Preferred diols which can be used in the present invention include ethylene oxide adducts of aromatic diols represented by the formula (2) shown by the formula (3) alone, aromatic diols of the formula (2) and aliphatic diols or silicone diols And preferred dianhydrides usable in the present invention are the aromatic organic acid dianhydrides of the formula (4) as follows.

(2)

(2)

(In the above formula (2), R ₂ is

(3)

(3)

(3), R < _{2 >} is

(In the above formula (4), R ₃ is

Polyols having an average molecular weight of 100 to 10,000 are used as the more preferable diols to be used in the present invention. Examples of the main chain structure include polypropylene glycol, polyethylene glycol, polypropylene glycol / polyethylene glycol copolymer, polytetramethylene glycol, poly (Adipate), poly (diethylene adipate), poly (propylene adipate), poly (tetramethylene adipate), poly (hexamethylene adipate), poly (neopentylene adipate) ), Poly-epsilon -caprolactone, poly (hexamethylene carbonate), and poly (siloxane).

The poly (urethane-imide) usable in the present invention can be obtained by reacting the above monomers, and is represented by the following formula (5).

(5)

(5)

(In the above formula (5), R ₁ is

One or two species are selected.

Z is an integer of 1 to 50, x = 0, y >> 1, and an imide block type polymer is formed. When x >> 0 and y = 1, a urethane block type polymer is formed.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are merely illustrative of the present invention and that the scope of the present invention is not limited thereto.

[ Example  One] Polyurethane imide  Suzy( PU -1) < / RTI >

0.010 mol of sufficiently dried ethylene glycol-bisphenol A-ethylene glycol (condensate of 1 mol of bisphenol A and 2 mol of ethylene oxide, EG-BPA-EG) was dissolved in 1-methyl-2-pyrrolidone (NMP) Then, diphenylmethane-4,4'-diisocyanate (1.0 mol), diphenylmethane-2,4'-diisocyanate (1.0 mol) and polytetramethylene glycol (0.8 mol) having an average molecular weight of 1,000 were mixed in a nitrogen atmosphere The mixture was gradually added dropwise, and then slowly stirred at 30 DEG C with a stirring rod.

The reaction was carried out at a temperature of 30 ° C in a nitrogen atmosphere for 5 hours, and then the temperature of the reactor was raised to about 80 ° C and a small amount of 0.005 mole of imidation catalyst sodium methoxide was added. While keeping the reaction temperature constant, the dihydrate, benzophenonetetracarboxylic dianhydride, was dissolved in dimethylacetamide (DMAc), and the solution was slowly added to the separating funnel with vigorous stirring. At this time, the ejection of CO ₂ was confirmed and the reaction was terminated when the maximum viscosity was reached. The solution obtained from the reaction was azeotroped in vacuo at 90 캜 for 8 hours to remove the solvent and residual unreacted material to obtain a polyurethane imide resin (PU-1).

The obtained polyurethane imide resin (PU-1) was mixed with the synthesized polyurethane imide resin (PU-1) using a static mixer module (M10) with enhanced mixing efficiency and a coating device equipped with a spray module (M2) 1) to the steel pipe efficiently.

First, 35 parts by weight of 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane as a curing agent for the polyurethane imide resin (PU-1), 35 parts by weight of a polyether amine 50 A curing agent containing 7 parts by weight of a pigment, 5 parts by weight of a chain extender, 5 parts by weight of a chain extender, a defoaming agent, a wetting agent and 3 parts by weight of a surface control agent. The mixture was mixed using a static mixer module (M10) having increased mixing efficiency at a solid weight ratio as shown in Table 1. At this time, it was confirmed that the mixing efficiency was constantly more than 90%. The polyurethane imide resin (PU-1) mixed with the hardener was uniformly sprayed on the steel pipe by using the fan-shaped injection module (M2) to produce a steel pipe coated with the polyurethane imide resin.

[ Example  2] Polyurethane imide  Suzy( PU -2) coated steel pipe

A polyurethane imide resin (PU-2) was synthesized in the same manner as in Example 1, except that poly (hexamethylene carbonate) having an average molecular weight of 2,000 was used instead of polytetramethylene glycol (0.8 mol) having an average molecular weight of 1,000 .

The obtained polyurethane imide resin (PU-2) was dissolved in methyl ethyl ketone at a solid content of 40% by weight, and then a static mixer module (M10) with enhanced mixing efficiency and a coating device equipped with a spray module (M2) To efficiently coat the synthesized polyurethane imide resin (PU-2) on a steel pipe.

First, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane was used as a curing agent for the polyurethane imide resin (PU-2), and as shown in Table 1, Using a static mixer module (M10) with enhanced mixing efficiency. At this time, it was confirmed that the mixing efficiency was constantly more than 90%. The polyurethane imide resin (PU-2) mixed with the hardener was uniformly sprayed on the steel pipe using the fan-shaped injection module (M2) to produce a steel pipe coated with the polyurethane imide resin.

[ Example  3] Polyurethane imide  Suzy( PU -3) < / RTI >

Similar to Example 1 except that polytetramethylene glycol (0.4 mol) and poly (hexamethylene carbonate) having an average molecular weight of 2,000 (0.4 mol) were used in place of polytetramethylene glycol (0.8 mol) having an average molecular weight of 1,000 To obtain a polyurethane imide resin (PU-3).

The obtained polyurethane imide resin (PU-3) was dissolved in methyl ethyl ketone at a solid content of 40% by weight, and then a static mixer module (M10) with enhanced mixing efficiency and a coating device equipped with a spray module (M2) To efficiently coat the synthesized polyurethane imide resin (PU-3) on a steel pipe.

First, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane was used as a curing agent for the polyurethane imide resin (PU-3), and as shown in Table 1, Using a static mixer module (M10) with enhanced mixing efficiency. At this time, it was confirmed that the mixing efficiency was constantly more than 90%. The polyurethane imide resin (PU-3) mixed with the hardener was sprayed uniformly onto the steel pipe by using the fan-shaped injection module (M2) to produce a steel pipe coated with the polyurethane imide resin.

[ Example  4] Polyurethane imide  Evaluation of adhesion strength of resin coated steel pipe

The steel tubes coated with the polyurethane imide resin prepared in Examples 1 to 3 were dried in an oven at 60 DEG C for 36 hours and then the bonding strength was measured by 90 degree peeling method according to JIS-Z0237, Respectively. The results are shown in Table 1 below as the bonding strengths (psi) of 1800, 1750 and 1770, confirming that the steel pipe of the present invention has excellent adhesive strength.

Table 1. Weight ratio and bonding strength of polyurethane imide resin and curing agent

M10: static mixer module S10: injection module
15: housing S01: connection with the static mixer module
17: S02: S02:
20: Laminar flow reduction means S03: Injection fine outlet
25: interference fringe
30: enlarged neck
40: Reduced neck
50: converging member
60:

Claims (8)

A method of manufacturing a steel pipe having a coating layer,
Mixing a polyurethane imide resin and a curing agent using a coating apparatus including a static mixer module and a spray module capable of enhancing mixing efficiency; And
And spraying the polyurethane imide resin mixed with the curing agent onto the inner or outer wall of the steel pipe, the method comprising the steps of:
The static mixer module includes: a housing having a flow path through which fluid can move;
A mixing member installed on the flow path and mixing two or more fluids passing through the flow path; And
And a laminar flow reduction means for reducing laminar flow formed at an edge of the flow path. delete The apparatus according to claim 1, wherein the laminar flow reduction means includes an interference fence protruding toward the center of the flow path; And an enlarged neck portion for temporarily enlarging the reduced diameter portion or the cross-sectional area of said flow passage temporarily reducing the cross-sectional area of said flow passage; And a collision member provided on an inner circumferential surface of the housing to collide with a convergent member that narrows the flow of the fluid that has passed through the mixing member and a fluid that has passed through the convergent member and disperses the fluid in a plurality of paths. A method for manufacturing a steel pipe having a resin coating layer. [5] The apparatus of claim 3, wherein the converging member includes a partition wall which is provided to block the flow path and has a converging hole penetrating in the forward and backward directions, and a guide pipe protruding from the back surface of the partition wall and connected to the converging hole Wherein the polyurethane imide resin coating layer comprises a polyurethane imide resin coating layer. [5] The apparatus as claimed in claim 4, wherein the collision member comprises: a body provided so as to block the flow path; a collision groove formed in the body and colliding with a fluid passing through the guide pipe; And a connecting groove formed on a front surface of the body and connecting the impingement groove and the dispersion passage. 2. The method of claim 1, wherein the polyurethane imide resin coating layer comprises a polyurethane imide resin coating layer. 6. The method of claim 5, wherein the impingement groove is provided with an interference member which hinders flow while colliding with the fluid introduced into the impingement groove. The method according to claim 1, wherein the spraying module is one of a nozzle having a polyurethane imide resin coating layer, the pattern of which is selected from a vortex chamber type, a deflection type, a spiral type, a circular type, a tapered rim type, Gt; delete

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