KR101402013B1 - Environment-friendly steel pipe coated with vegetable paint and its manufacturing method - Google Patents

Abstract

The present invention relates to an eco-friendly steel pipe coated with vegetable polyurethane paint used for water supply used for public premises piping and underground laying, general water supply, seawater and plant piping, and crude oil tank and piping. The inside of the steel pipe is coated with vegetable polyurethane paint and the outside of the pipe is coated with the vegetable polyurethane paint or polyethylene paint in order to protect the pipe from all kinds of corrosion environments and provide an eco-friendly steel pipe without harmful substances. Existing liquid epoxy or polyurea containing petroleum polyol as a main ingredient is used as inside coating materials but in contrast, according to the present invention, the inside of the pipe is coated with the vegetable polyurethane paint to prevent harmful substances and because a chemical matter property of the vegetable polyurethane paint is excellent, an ideal coated film is formed and adhesive force is improved to reduce a side effect of peeling the coated film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an environmentally friendly steel pipe coated with vegetable paint,

The present invention relates to an environmentally friendly steel pipe coated with a vegetable paint and a method for producing the same.

Generally, a steel pipe used for fluid transportation corrodes the inner wall of the steel pipe by the fluid flowing inside, and the steel component on the inner surface of the steel pipe is dissolved, thereby contaminating the water quality. Corrosion of the inner wall also directly affects the durability of the steel pipe, and contaminates the fluid moving through the steel pipe. In order to prevent corrosion, it is common to coat paints on inner and outer surfaces of steel pipes.

The inner surface coating of steel pipes used in Korea is defined as 'Liquid epoxy' by Korean Industrial Standard KS D 3565 for 'Welded Steel Pipes for Waterworks'. 'Liquid epoxy' is superior to other paints in terms of water resistance, chemical resistance and heat resistance. It is used as an inner coating for water pipes. However, it has weak adhesive strength and it is possible to remove paint by using solvents containing harmful components of benzene and toluene There is a great risk of dissolution of harmful components.

In addition to 'liquid epoxy', 'Polyurea' is used to coat the inner surface of steel pipes. However, 'Polyurea' is also a raw material extracted from petroleum. It is a heavy metal such as lead, chromium, cadmium, Toxic substances may be generated in the drinking water, and when used as a water pipe, harmful components may be contained in drinking water.

Korean Patent No. 10-1106593 discloses a vegetable polyurethane coating which is sprayed simultaneously on the inner and outer surfaces of a steel pipe mixed with a vegetable polyurethane paint and a quick drying agent to form a vegetable polyurethane coating which is harmless to the human body and is environmentally friendly A steel pipe coating apparatus of a vegetable polyurethane paint that can provide a steel pipe has been proposed. However, only the constitution of such a paint apparatus is described, and the structure of the environmentally friendly steel pipe which is harmless to the human body, I do not mention it.

Conventionally, development of eco-friendly paints using natural vegetable compounds or their derivatives has been attempted. However, most of them have a problem that the performance of the coated film is below the required level, and the cost is too high and economical. It has been difficult to apply it to a steel pipe which is used for a water supply pipe which is inexpensive in manufacturing cost and which requires excellent coating film performance.

Environment-friendly steel pipe excellent in adhesion, durability, weather resistance, abrasion resistance, water resistance and the like while being harmless to the human body due to the absence of environmental hormones, heavy metals and organic compounds. It is another object of the present invention to provide a method of manufacturing such an environmentally friendly steel pipe.

According to one aspect of the present invention, there is provided a method for manufacturing a green-made steel pipe coated with a two-part vegetable polyurethane paint, which is a solventless two-part type, comprising 18 to 34% by weight of a petroleum-based polyetherpolyol, 70 to 70% by weight of methylene diphenyldiisocyanate (MDI) To 75% by weight and HDI (hexamethylene diisocyanate) in an amount of 7 to 11% by weight, spraying a first liquid as an isocyanate prepolymer and spraying the first liquid onto the inner surface of the steel pipe, Having a polyol mainly composed of 30 to 70% by weight of a derived modified polyol, 8 to 25% by weight of an aromatic secondary amine, 10 to 30% by weight of a tetrafunctional tertiary amine polyol and 8 to 15% Wherein the first liquid and the second liquid are in the form of a solventless two-pack type vegetable polyurethane paint which is contained in an amount such that the NCO content is 20 to 23% by weight.

Wherein the step of spraying the first liquid onto the inner surface of the steel pipe and the step of spraying the second liquid are performed by equally injecting the first liquid and the second liquid on the inner surface of the steel pipe at a ratio of 1: 1 solution and the second solution are mixed and coated at a ratio of 1: 1.

Spraying the first liquid and the second liquid simultaneously on the inner surface of the steel pipe and injecting the first liquid and the second liquid onto the inner surface of the steel pipe and simultaneously injecting the first liquid and the second liquid onto the outer surface of the steel pipe, And injecting the gas.

The steel pipe is formed by spraying a polyethylene paint comprising 1 to 30% by weight of a polyethylene resin, 1 to 20% by weight of a copolymer having an organic functional group and 50 to 98% by weight of solvent on the outer surface of the steel pipe, Coating.

The steel pipe is formed by adding, on the outer surface of the steel pipe, a first liquid as an isocyanate prepolymer of 45 to 60 wt% consisting of 2,4-4,4-MDI or carbonate-modified MDI or a derivative thereof and a first liquid as a polyether amine or a low molecular weight amine And 40 to 55% by weight of the second liquid.

According to another aspect of the present invention, an environmentally friendly steel pipe coated with a solventless two-pack type vegetable polyurethane paint is coated on the inner surface of a steel pipe and the steel pipe and comprises 18 to 34% by weight of a petroleum-based polyether polyol, A first liquid as an isocyanate prepolymer composed of 55 to 75% by weight of diphenyldiisocyanate and 7 to 11% by weight of HDI (hexamethylene diisocyanate), 30 to 70% by weight of modified polyol derived from vegetable oil, 8 to 25% And a second liquid containing as a main component a polyol comprising 10 to 30% by weight of a tetrafunctional tertiary amine polyol and 8 to 15% by weight of an additive, and a first inner surface coating layer which is a two-part plantless polyurethane paint And the solventless two-pack type polyurethane paint is contained in an amount such that the NCO content of the first liquid and the second liquid is 20 to 23% by weight.

The outer surface of the steel pipe may include an outer surface coating layer which is a non-solvent two-pack type vegetable polyurethane paint.

The steel pipe may include a first outer coating layer on the outer surface of the steel pipe, which is a polyethylene paint comprising 1 to 30% by weight of a polyethylene resin, 1 to 20% by weight of a copolymer having an organic functional group, and 50 to 98% by weight of a solvent.

The first outer coating layer may be formed on the outer surface of the steel pipe coated with the second outer coating layer, and the first outer coating layer may be formed on the outer surface of the steel pipe coated with the second outer coating layer. do.

A third outer coating layer made of a powdered epoxy primer may be further disposed between the outer surface of the steel pipe and the second outer coating layer and the second outer coating layer is coated on the outer surface of the steel pipe coated with the third outer coating layer .

Wherein the steel pipe comprises an outer surface of the steel pipe which is made of a first liquid as an isocyanate prepolymer of 45 to 60 weight% composed of 2,4-4,4-MDI or carbonate-modified MDI or a derivative thereof and a second liquid as a polyether amine or a low molecular weight amine And a first outer coating layer which is a polyurea coating comprising 40 to 55% by weight of a second liquid.

The environmentally friendly steel pipe coated with a vegetable-free paint using various modified polyols obtained by modifying vegetable oil as a main material is harmless to the human body due to no detection of environmental hormones, heavy metals, organic compounds, etc. and has a short drying time after coating, , Abrasion resistance, water resistance, and the like.

1 is a flowchart of a method of manufacturing an environmentally friendly steel pipe in which an inner surface and an outer surface of a steel pipe according to an embodiment of the present invention are coated with a vegetable polyurethane paint.
2 is a schematic view of an environmentally friendly steel pipe coated with a vegetable polyurethane paint on the inner and outer surfaces of a steel pipe according to an embodiment of the present invention and a sectional view of the steel pipe segment.
3 is a flowchart of a method of manufacturing an environmentally friendly steel pipe in which polyethylene is coated on the outer surface of a steel pipe and a vegetable polyurethane paint is coated on the inner surface according to an embodiment of the present invention.
4 is a cross-sectional view of a steel pipe section and a schematic view of an environmentally friendly steel pipe in which polyethylene is coated on the outer surface of a steel pipe according to an embodiment of the present invention and a vegetable polyurethane paint is coated on the inner surface.
5 is a flowchart of a method of manufacturing an environmentally friendly steel pipe in which a polyurea coating is applied to the outer surface of a steel pipe according to an embodiment of the present invention and a vegetable polyurethane paint is coated on the inner surface.
6 is a schematic view of an environmentally friendly steel pipe having a polyurea coated on the outer surface of a steel pipe according to an embodiment of the present invention and coated with a vegetable polyurethane paint on the inner surface thereof, and a sectional view of the steel pipe segment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the process of studying eco-friendly steel pipes suitable for applications such as water supply pipes, which require low cost of production and excellent coating performance, various types of polyols are obtained by modifying vegetable oils, and then subjected to a wide range of tests for formulating them into two-component polyurethane paints As a result, the inventors have developed an eco-friendly steel pipe coated with a vegetable polyurethane paint which is non-toxic and has excellent resistance to salt and weathering, abrasion resistance, water resistance, impact resistance, adhesion strength, flexibility and hardness. Embodiments of the present invention described below relate to such environmentally friendly steel pipes and a method of manufacturing the same.

1 is a flowchart of a method of manufacturing an environmentally friendly steel pipe according to an embodiment of the present invention. Referring to FIG. 1, in step 11, a steel pipe having a shape conforming to the requirements of the purchaser is manufactured from a straight pipe type pipe using a cutter, a welder, or the like. More specifically, after cutting a circular pipe, a steel pipe having a shape conforming to the requirements of the purchaser is manufactured by welding a circular pipe cut according to the required form by the purchaser. In the production of steel pipes used for waterworks, the material of the pipes is to comply with KS D 3565 for waterworks, and according to KS D 3565, the steel or steel plates are to be tubular and subjected to submerged arc welding The shape of the pipe is completed. The pipes are to be constructed in accordance with KS D 3578, and both ends of the steel pipes shall be of bell and spigot joint type and shall be constructed so that at least 60 to 80 mm of double joints are allowed at pipe joints.

In step 12, a shot blasting apparatus or a grit blasting apparatus is used to apply a plurality of shots or grit to the inner and outer surfaces of the steel pipe manufactured in step 11, Scales, rust, paint film, etc. attached to the inner and outer surfaces of the steel pipe are projected by projecting a sharp angle-shaped steel strip crushed by a ball mill or a hammer mill. Here, shot blasting refers to a method of spraying a plurality of shots onto a metal surface together with compressed air to remove contaminants attached to the metal surface. Grit blasting refers to a method of removing contaminants adhered to a metal surface by spraying a plurality of grit on a metal surface together with compressed air.

In step 13, the steel pipe with the contaminants removed in step 12 is heated in an enclosed chamber. The heating temperature of the surface of the steel pipe depends on the weather and humidity of the area where the steel pipe is located. When the temperature of the surface of the steel pipe is lower than the current temperature by 3 ° C or more, the adhering force of the substance adhering to the surface of the steel pipe is the highest. Meanwhile, in order to further improve the adhesion of the material to the surface of the steel pipe, the surface of the steel pipe may be cleaned with high-pressure steam before heating the steel pipe.

In step 14, 18 to 34% by weight, preferably 20 to 32% by weight of petroleum polyether polyol, 55 to 75% by weight of MDI (methylene diphenyl diisocyanate), preferably 60 to 72% by weight of petroleum- And 7 to 11% by weight, preferably 8 to 10% by weight, of HDI (hexamethylene diisocyanate) is injected as an isocyanate prepolymer.

The isocyanate, which is the main raw material of the first liquid, reacts with a petroleum-based polyol as a hardening agent to impart flexibility of the steel pipe coating. The selection of the type of isocyanate and the content of NCO is important as the first liquid isocyanate prepolymer is a very important part that determines hardness, flexibility, adhesion, curability, reaction stability, and chemical resistance of the coating film. As the isocyanate used as the first solution, monomeric (monomeric) and polymeric (polymeric) forms are used. Mono-isocyanate is high in volatility and is harmful to the human body and is excessively high in the degree of crosslinking. Thus, it is difficult to design a 1: 1 volume ratio for application of the first liquid and the second liquid to the back portion immediately before coating. Of course, all of the polymerizable isocyanates were urethane-reacted with the petroleum-based polyol to give flexibility to the steel pipe coating by adjusting the NCO content to 20 to 23% by weight and spraying. Also, it is preferable that the viscosity of the first liquid prepared by the above-described method is 800 to 1800 cps (80 to 100 KU) and the specific gravity is 1.13 to 1.15 when spraying the paint through the steel pipe coating apparatus.

 In the present invention, monomelic MDI as the monomeric isocyanate is preferably 33 to 34% by weight, and polymeric MDI having 30 to 32% by weight NCO content can be preferably used as the polymerizable isocyanate. As the low-viscosity HDI, NCO Oligomeric HDI, preferably trimer, having a content of 22 to 25% by weight and a viscosity of 400 to 1400 cps (about 65 to 95 KU) is used.

When the content of MDI is less than 55% by weight, the viscosity becomes high and it is difficult to inject into the steel pipe. When the MDI content is more than 75% by weight, the reaction is too rapid at the time of injection into the steel pipe, I can not.

When the content of the low viscosity HDI is less than 7% by weight or exceeds 11% by weight, a coating material having a viscosity suitable for the first liquid is not produced, and the reactivity with the polyol is also increased or decreased to make it impossible to form an ideal coating film. Lt; / RTI >

The petroleum-based polyol used in the first liquid is, for example, a polyether polyol such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol and a polyol such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, Heptane diol, octane diol, neopentyl glycol, diethylene glycol, and dipropylene glycol. The reason why the petroleum-based polyol is used without using the modified polyol derived from the vegetable oil as the polyol of the first liquid is that the modified polyol derived from the vegetable oil of the second liquid to be described later has a high viscosity and is used for both the first solution and the second solution It is difficult to spray when painting. However, a small amount of petroleum-based polyol is used in the first liquid, and the used isocyanate prepolymer releases a toxic substance in a gaseous form in the course of the reaction and exists in a stable form of solid after completion of the reaction with the second liquid to be described later. Also, the second component of the vegetable polyurethane coating material coated on the environmentally friendly steel pipe of the present invention is a polyol derived from vegetable oil, which accounts for 30 to 70% by weight of the total composition. Thus, the vegetable polyurethane coating composition of the present invention There is no problem in implementing environmentally friendly steel pipes.

In step 15, using the coating apparatus, at the same time as the injection in step 14, 30 to 70% by weight of modified polyol derived from vegetable oil, 8 to 25% by weight of aromatic secondary amine and 10 to 30% by weight of tetrafunctional tertiary amine polyol By weight, and 8 to 15% by weight of other additives.

The first liquid and the second liquid are simultaneously injected in the same ratio at a ratio of 1: 1 on the inner surface of the steel pipe, whereby the first liquid and the second liquid are impinged and mixed at a ratio of 1: 1, Solution is a solvent-free two-pack type vegetable polyurethane paint which has an NCO content of 20 to 23% by weight and is coated on the inner surface of a steel pipe.

An example of a coating apparatus for spraying the first liquid and the second liquid simultaneously on the inner surface of a steel pipe and impinging the mixture is a coating apparatus disclosed in Korean Patent No. 10-110693. In addition to this, Reactor XP-2 of Graco Co., USA and Reactor E-10 which is a simple testing device can be used as a coating device for simultaneously spraying the first liquid and the second liquid on the inner surface of the steel pipe. The vegetable paint of the present invention is designed as a solvent-free solvent-free paint and is unsuitable for coating with a spraying apparatus of the general spray type. In order to spray using the above-mentioned specific apparatus, the viscosity of the paint is 50 to 100 KU , And the same amount of the first solution and the second solution should be used in a ratio of 1: 1 (see Examples 39 to 44, which will be described later).

Next, the second liquid of the vegetable polyurethane paint which is in contact with the first liquid and reacted and coated on the steel pipe will be described.

The second liquid of the vegetable polyurethane paint is a desiccant which reacts with moisture in reaction with a polyol part derived from a vegetable oil which functions as a chain extender, a cross-linking agent for improving the cross-linking density of the polyol and isocyanate, A pigment for determining the color of the paint, a dispersing agent for mixing the pigment well, a defoaming agent for eliminating air bubbles generated during the reaction, and a stabilizer.

The vegetable polyol, which is a main component of the second solution, is designed to have an NCO content of 30 to 70% by weight, preferably 40 to 62% by weight. It functions as a chain extender, and forms a soft segment (called a segment, when a polymer is regarded as a repetition of a partial chain composed of several constituent repeating units, also referred to as a segment) to impart flexibility. The NCO content of the vegetable polyol in the vegetable polyurethane paint sprayed together with the first liquid and coated on the steel pipe has been appropriately selected in consideration of flexibility and environment friendliness. Although the vegetable polyol has a large molecular weight, when it is used alone, the elasticity is improved. However, due to the nature of the polymer, the degree of crosslinking is weak and the physical properties such as chemical resistance and solvent resistance are lowered and used with the crosslinking agent.

In the present invention, amines or various kinds of polyols are used as crosslinking agents. In the case of a polyol having no primary amine or amine group, the reaction with the isocyanate is fast and difficult to control, and the reaction is not uniform. If this is sprayed, the gelation time of the coating film is very short, so that the coating film is crosslinked at the same time as the spraying, so that a coating film having good leveling (smoothening) can not be formed. Table 1 shows the types and characteristics of the crosslinking agent used in the second solution.

Types and properties of crosslinking agents Cross-linking
Kinds Reactivity
(Isocyanate) Reaction catalyst problem Usability Aromatic primary amine 5 Unnecessary Too fast reactivity X Aromatic secondary amine 4 Unnecessary - O Tetrafunctional tertiary amine polyol 3 Unnecessary - O Tetrafunctional polyol 2 need Reactivity with Moisture by Catalyst X Trifunctional petroleum polyol One need Catalyzed
Reactivity with moisture X

In Table 1, the crosslinking agent shows the reactivity of a tetrafunctional polyol such as an aromatic primary amine, an aromatic secondary amine, a tetrafunctional polyol tertiary amine, a tetrahydroxylpolyol, or the like, or a trifunctional petroleum-based polyol and a polyamine. The aromatic primary polyamine having a high reactivity or the tetrafunctional polyol having no amine group may not be uniformly reacted and the reaction time may be too fast to generate bubbles during the reaction. The tetrafunctional polyol tertiary amine has an autocatalytic crosslinking structure having four functional groups and at the same time a tertiary amine. Tetrahydroxylpolyol tertiary amine used as the second solution is suitable as a crosslinking agent component of the second solution because it has appropriate reactivity without any other additives such as a reaction catalyst and for the same reason, an aromatic secondary amine can also be used as a crosslinking agent.

The vegetable polyol used in the second solution is obtained by modifying soybean oil and linseed oil. It is also possible to use castor oil, rapeseed oil, cottonseed oil, palm oil, palm kernel oil, and Jatropha oil, but the efficiency of the reforming operation And use of soybean oil and flaxseed oil is preferable considering the economical efficiency of raw material purchase. The polyol modified from the vegetable oil may be a methoxy polyol, a hydroxyl polyol, a hydroxyl fatty acid methyl ester-introduced polyol, or an acrylate ester polyol, and a mixture of two or more thereof may be used. The polyol derived from the vegetable oil described above forms a non-hydrophilic, smooth level surface coating film surface.

On the other hand, when a polyether-based or polyester-based polyol having a relatively monomolecular form, which is a petroleum-based polyol, is used, not only the water content (moisture content) is high but also the probability of forming a urethane foam after spray painting The possibility of causing a problem in the coating film on the surface of the steel pipe becomes high.

From the viewpoint of the reaction between the polyol and MDI, the modified polyol derived from vegetable oil is much more reactive to moisture than the petroleum-based polyol, and is effective in forming an ideal film.

The polyol derived from the vegetable oil according to the present invention can form a coating film having good leveling on the surface of a steel pipe when used together with the above-mentioned cross-linking agent and is a completely solvent-free coating material which does not need to be mixed with a solvent for spraying into a coating apparatus. To < RTI ID = 0.0 > 90s. ≪ / RTI > Table 13 and Table 15 show the gelation time of the steel pipe test piece coatings according to the examples. The vegetable paint forms an ideal coating film when the first liquid and the second liquid are sprayed to the coating apparatus at an equal ratio of 1: 1. This will be described in Examples 39 to 44 to be described later.

On the other hand, the second liquid contains 8 to 15% by weight of a dispersing agent, defoaming agent, dehumidifying agent, pigment, stabilizer and the like as other additives. The above-mentioned dispersant is an additive for preventing connection and aggregation of pigment molecules, and has high stability according to the opacity and regulation of volatile organic compounds (VOC), and alkylol ammonium salt is used to shorten dispersion time. Polysiloxane or silicone oil is used as a defoaming agent to remove bubbles during the formation of a film, aluminum silicate as a dehumidifying agent, and triethyl orthoformiate as a stabilizer. All of these materials are publicly used in the art, and besides these, substances known in the art can be selected and used as needed.

Urethane curing catalyst may be used for steel pipe coating. The catalyst for urethane curing according to an embodiment of the present invention may further contain 0.3 to 0.5 wt% of dibutyltin dilaurate (DBTDL), and may be used in combination with a decrease in aromatic secondary amine content in the second solution When the content of the tetrafunctional polyol tertiary amine crosslinking agent is accompanied, it is necessary to control the curing rate by adding it. The use of DBTDL has the advantage of accelerating the reactivity and reducing the tack free time. However, it has a disadvantage in that the wetting time of the steel pipe is not sufficient and the adhesion force is further lowered. In order to lower the viscosity of the second liquid, an alkylene oxide polyol may be further added in an amount of 5 to 20 wt%, which may be replaced with a material known in the art.

In step 16, 18 to 34 wt% of a petroleum-based polyether polyol, 55 to 75 wt% of MDI (methylene diphenyl diisocyanate), 7 to 10 wt% of hexamethylene diisocyanate (HDI) To 11% by weight of an isocyanate prepolymer.

In step 17, in addition to spraying in steps 14 to 16 using a coating apparatus, 30 to 70% by weight of modified polyol derived from vegetable oil, 8 to 25% by weight of aromatic secondary amine, and 4 to 10% by weight of tetrafunctional tertiary amine polyol 10 To 30% by weight, and the other additives are 8 to 15% by weight. In this manner, the first liquid and the second liquid are injected in the same amount in the ratio of 1: 1 at the same time on the outer surface of the steel pipe, whereby the first liquid and the second liquid are impinged and mixed at a ratio of 1: 1, And the second solution are coated on the outer surface of the steel pipe with a solventless two-pack type vegetable polyurethane paint so that the NCO content is 20 to 23% by weight.

The thickness of the coating on the environmentally friendly steel pipe in steps 14 to 17 depends on the nominal diameter (A) of the pipe, see Table 2 below.

Nominal diameter of pipe (A) Cladding Thickness (mm) Remarks 80 - 150 2.0 or higher The coating thickness refers to all the coating layers of primer, adhesive and paint on the surface of the steel pipe, and the coating thickness of the welded area is allowed up to -10%. 200 - 1000 2.5 or more 1,100 - 2,000 3.0 or higher 2,100 - 3,000 3.5 or higher

Table 3 shows the uncoated length of both ends of the steel pipe according to the nominal diameter at the time of coating the steel pipe.

Nominal diameter (A) Paint Length 700 or less 150mm ± 10mm 800 - 1,100 175mm ± 10mm 1,200 - 1,650 200mm ± 10mm More than 1,800 250mm ± 10mm

In step 18, the coated steel tube is cooled according to the conditions of Tables 2 and 3. In step 19, the end of the steel tube, which has been left unrecorded, is formed into a bell and spigot joint shape .

2 is a schematic view of a green steel pipe manufactured according to the manufacturing method shown in FIG. 1 and a sectional view of a steel pipe section. 2, an environmentally friendly steel pipe 2 according to an embodiment of the present invention is coated on the inner surface of a steel pipe 20 and comprises 18 to 34% by weight of a petroleum-based polyether polyol, 55 to 75% by weight of MDI (Methylene Diphenyl Diisocyanate) , 30 to 70 wt% of a modified polyol derived from a vegetable oil, 8 to 25 wt% of an aromatic secondary amine and 4 to 10 wt% of a tetrafunctional tertiary amine And a second liquid containing as a main component a polyol comprising 10 to 30 wt% of a polyol and 8 to 15 wt% of other additives.

The environmentally friendly steel pipe 2 is coated on the outer surface of the steel pipe 20 and contains 18 to 34 wt% of petroleum-based polyether polyol, 55 to 75 wt% of MDI (methylene diphenyl diisocyanate), 7 to 11 wt% of HDI (hexamethylene diisocyanate) % Of a modified polyol derived from vegetable oil, 8 to 25% by weight of an aromatic secondary amine, 10 to 30% by weight of a tetrafunctional tertiary amine polyol, and 8 to 30% (Ii) a second liquid containing a polyol as a main component, wherein the second liquid contains a polyol as a main component.

1 is a result of the manufacturing process shown in Fig. 1, a more detailed description of the vegetable polyurethane coating material coated on the inner and outer surfaces of the steel pipe 20 is given in Fig. 1 The description of the manufacturing method shown in Fig.

In addition to the vegetable polyurethane paint, the outer surface of the environmentally friendly steel pipe can be coated with a polyethylene paint or a polyurea paint.

3 is a flowchart of a method for manufacturing an environmentally friendly steel pipe coated with a polyethylene paint on the outer surface of a steel pipe according to an embodiment and a vegetable polyurethane paint coated on the inner surface thereof. In steps 31 to 33, Is the same, and is a preprocessing process for preparing a steel pipe to be coated. The preheated steel pipe is coated first. Since the outer surface and inner surface of the steel pipe are coated differently, the end of the steel pipe is fastened with a stopper to prevent the paint from mixing.

In step 34, the powder epoxy is coated on the outer surface of the steel pipe by spraying powder epoxy of the primer material on the outer surface of the steel pipe using a coating apparatus. The coated powder epoxy is coated to improve adhesion of the adhesive, which will be described later, and to improve corrosion resistance. In step 35, the outer surface of the steel pipe is sprayed with an adhesive material modified with polyethylene to the outer surface of the powder epoxy layer, and the outer surface of the steel pipe is coated by spraying a polyethylene paint onto the outer surface of the polyethylene adhesive modified in step 36. More specifically, a mixture of 1 to 30% by weight of a polyethylene resin and 1 to 20% by weight of a copolymer having an organic functional group and 50 to 98% by weight of a solvent is sprayed on the outer surface of a steel pipe. The composition ratio of the polyethylene mixture is designed considering the leveling, water content, adhesion, hardness, abrasion resistance, chemical resistance, etc. of the coating film formed by spraying on the surface of the steel pipe. This is cheaper than the environmentally friendly steel pipes coated with vegetable polyurethane paint on the inner and outer surfaces of the steel pipe shown in FIG. 2, but the inner surface of the steel pipe is coated with the vegetable polyurethane paint to prevent contamination of the fluid conveyed through the inside of the environmentally friendly steel pipe It is not contrary to the object of the present invention to provide an eco-friendly steel pipe. In addition to this, a polyethylene coating technique known in the art can be used, and a detailed description will be omitted because it can obscure the technical content of the present invention.

The outer surface of the steel pipe is coated with a polyethylene paint, then the end cap is removed and the inside is coated.

Steps 37 and 38 are the same as those of steps 14 and 15 of FIG. 1, respectively, in which the inside of the steel tube is coated with a vegetable polyurethane paint. Briefly, the first and second liquids of the above- Spraying by simultaneous spraying by an impingement sprayer.

Steps 39 and 300 are the same as steps 18 and 19 of FIG. 1 for cooling the coated green steel pipe and machining the end portion.

FIG. 4 is a schematic view of a green steel pipe manufactured according to the manufacturing method shown in FIG. 3 and a sectional view of a steel pipe section. 4, an environmentally friendly steel pipe 4 according to an embodiment of the present invention is coated on the outer surface of a steel pipe 40 and comprises 1 to 30% by weight of a polyethylene resin, 1 to 20% by weight of a copolymer having an organic functional group, And a polyethylene coating layer 44 of 50 to 98% by weight of a solvent. The environmentally friendly steel pipe 4 is disposed between the outer surface of the steel pipe 40 and the polyethylene coating layer 44 to increase the adhesion of the polyethylene coating layer 44 to the powder epoxy 42 coated on the outer surface of the steel pipe 40 And a modified polyethylene adhesive 43 applied between the powder epoxy 42 and the polyethylene coating layer 44 and sprayed onto the outer surface of the steel pipe 40 to be coated thereon.

The inner surface of the steel pipe 40 is composed of a first liquid as an isocyanate prepolymer composed of 18 to 34% by weight of a petroleum-based polyether polyol, 55 to 75% by weight of MDI (methylene diphenyldiisocyanate) and 7 to 11% by weight of HDI (hexamethylene diisocyanate) A polyol having a main component of 30 to 70% by weight of modified polyol derived from vegetable oil, 8 to 25% by weight of aromatic secondary amine, 10 to 30% by weight of tetrafunctional tertiary amine polyol and 8 to 15% by weight of other additives And a coating layer 41 of a solvent-free two-pack type vegetable polyurethane paint containing a second liquid

The vegetable polyurethane paint 41 coated on the inner surface of the steel pipe 40 is a product produced according to the manufacturing method shown in FIG. 3, and the environmentally friendly steel pipe 4 shown in FIG. Refer to the above description with the same composition and method as the vegetable polyurethane paint.

5 is a flowchart of a method for manufacturing an environmentally friendly steel pipe in which a polyurea is coated on the outer surface of a steel pipe according to an embodiment of the present invention and a vegetable polyurethane paint is coated on the inner surface. The steps and the method are the same, and briefly, it is the preprocessing process to prepare the steel pipe to be coated. The preheated steel pipe is coated first. Since the outer surface and inner surface of the steel pipe are coated differently, the end of the steel pipe is fastened with a stopper to prevent the paint from mixing.

In step 54, 45 to 60% by weight of an isocyanate prepolymer consisting of 2,4-4,4-MDI or carbonate-modified MDI or a derivative thereof is added to the outer surface of the steel pipe using a coating apparatus and a solution of a polyetheramine or a low molecular weight By weight of a second liquid consisting of 40 to 55% by weight of an amine, and coating the outer surface of the steel pipe. The first liquid of the above-mentioned isocyanate prepolymer composed of 2,4-4,4-MDI or carbonate-modified MDI or a derivative thereof is used as a curing agent, and a monomer, polymer MDI can be used. As the second liquid, a polyetheramine or a low molecular weight React with amines to form urea bonds. The composition ratio of the first liquid isocyanate prepolymer to the second liquid polyether amine or the low molecular weight amine is determined by considering the leveling, water content, adhesion, hardness, abrasion resistance, and chemical resistance of the surface coating of the steel pipe coated with the first solution and the second solution I chose an excellent range. This is less expensive than the environmentally friendly steel pipe coated with vegetable polyurethane paint on the inner surface and outer surface of the steel pipe shown in FIG. 2, but the inner surface of the steel pipe is coated with a vegetable polyurethane paint to prevent contamination of the fluid conveyed through the inside of the environmentally friendly steel pipe It is not contrary to the object of the present invention to provide an eco-friendly steel pipe. The polyurea coating technique used in the steel pipe coating may be any of those known in the art, and the detailed description thereof will be omitted because it can obscure the technical content of the present invention.

After the outer surface of the steel pipe is coated with a polyurea paint, the end of the end is removed and the inside is coated.

Steps 55 and 56 are the same as those of steps 14 and 15 of FIG. 1 as a process of coating the inside of a steel pipe with a vegetable polyurethane paint. Briefly, the first and second liquids of the above- Spraying by simultaneous spraying by an impingement sprayer.

Steps 57 and 58 are the same as steps 18 and 19 of FIG. 1 for cooling the coated green steel pipe and machining the end portion.

6 is a schematic view of a green steel pipe 6 manufactured according to the manufacturing method shown in FIG. 5 and a cross-sectional view of a steel pipe section. 6, an environmentally friendly steel pipe 6 according to an embodiment of the present invention is coated on the outer surface of a steel pipe 60, and is coated with a metal such as 45-450-MDI or carbonate-modified MDI or a derivative thereof To 60% by weight of an isocyanate prepolymer, and 40 to 55% by weight of a second liquid comprising a polyetheramine or a low molecular weight amine.

The inner surface of the steel pipe 60 is composed of 18 to 34% by weight of a petroleum-based polyether polyol, 55 to 75% by weight of MDI (methylene diphenyldiisocyanate) and 7 to 11% by weight of HDI (hexamethylene diisocyanate) as a first liquid as an isocyanate prepolymer A polyol having a main component of 30 to 70% by weight of modified polyol derived from vegetable oil, 8 to 25% by weight of aromatic secondary amine, 10 to 30% by weight of tetrafunctional tertiary amine polyol and 8 to 15% by weight of other additives And a coating layer 61 of a solvent-free two-pack type vegetable polyurethane paint containing a second liquid.

The vegetable polyurethane paint 61 coated on the inner surface of the steel pipe 60 is a product obtained by the manufacturing method shown in FIG. 5, and the environmentally friendly steel pipe 6 shown in FIG. Refer to the above description with the same composition and method as the vegetable polyurethane paint.

Hereinafter, eco-friendly steel tubes coated with vegetable paints having various composition ratios were made to make respective examples. This is for the purpose of clarifying the present invention, and the present invention is not limited by the examples.

Each of the following examples was sprayed onto a test piece made of a part of a steel pipe, and the prepared test piece had the same physical and chemical properties as the steel pipe.

< Example  1> Vegetable of second liquid sprayed on steel pipe Polyol  Produce : Epoxidation  Soybean oil Epoxidation  oil)

1) A thermometer, a reflux condenser, and a stirrer are attached to a 2 L three-necked flask, then 800 g of soybean oil (iodine 132) is added and stirred slowly.

2) After heating 1) to 70 ° C, 110 g (4.78 mol) of 80% strength formic acid is added for 0.5 to 1 hour.

3) A mixed solution of 634 g (16.3 mol) of 35% hydrogen peroxide and 47.2 g of phosphoric acid at 85% concentration is slowly added to the flask over 1 to 5 hours, and the reaction is carried out at 70 ° C. for 10 hours.

4) After completion of the reaction, the organic layer is separated, washed with distilled water until the pH becomes neutral, dried under reduced pressure in a rotary evaporator, and filtered.

< Example  2> Vegetable of second liquid sprayed on steel pipe Polyol  Produce : Methoxy Polyol

1) A thermometer, a reflux condenser and a stirrer were attached to a 2 L three-necked flask, and 800 g of the epoxidized soybean oil synthesized in Example 1 was added thereto and stirred slowly.

2) After heating slowly to 50 캜, 800 g of methanol and 15.36 g of maleic acid as a catalyst are added, reacted for 5 hours, and a hydroxyl group is added.

3) After completion of the reaction, NaHCO ₃ 32 g is added and reaction is carried out for 30 minutes.

4) Filter to remove salt due to neutralization, and dry under reduced pressure in a rotary evaporator to remove excess methanol.

< Example  3> Vegetable of second liquid sprayed on steel pipe Polyol  Produce : Hydroxyl Polyol

1) A thermometer, a reflux condenser and a stirrer are attached to a 2 L three-necked flask, and 800 g of the epoxidized soybean oil of Example 1 is introduced.

2) While heating slowly to 50 ° C, 800 g of water and 15.36 g of maleic acid as a catalyst are added and reacted for 5 hours.

3) After the reaction is completed, 32 g of NaHCO ₃ is added to neutralize and further reaction is carried out for 30 minutes.

4) Filtration to remove salts due to neutralization, and drying under reduced pressure in a rotary evaporator to remove excess water.

< Example  4> Vegetable of second liquid sprayed on steel pipe Polyol  Produce : Epoxidation  Fatty acid methyl ester

The epoxidized soybean oil of Example 1 was converted to the methyl ester type from the triglyceride type by methylation reaction and was prepared as an intermediate for the synthesis of the modified polyol

1) A thermometer, a reflux condenser and a stirrer are attached to a 2 L three-necked flask, and then 800 g of epoxidized soybean oil is added.

2) After heating to 80 ° C with gentle stirring, a mixed solution of 160 g of methanol and 8 g of NaOH as an alkali catalyst is added and reacted for 1 hour.

3) After completion of the reaction, remove the lower layer of the solution to remove glycerin and repeat the same two times.

4) After completion of the reaction, wash with soap to remove soap, and dry under reduced pressure in a rotary evaporator to remove moisture.

< Example  5> Vegetable of the second liquid sprayed on the steel pipe Polyol  Produce : Hydroxyl  fatty acid methyl  ester

1) A thermometer, a reflux condenser and a stirrer are attached to a 2 L three-necked flask, and 800 g of the epoxidized fatty acid methyl ester obtained in Example 4 is introduced.

2) While heating slowly to 90 ° C, 800 g of water and 60 g of maleic acid as a catalyst are added and reacted for 12 hours or more.

3) To neutralize, 120 g of NaHCO ₃ is added and reacted for another 30 minutes.

4) After the reaction is completed, the resulting salt is removed by filtration and dried under reduced pressure in a rotary evaporator to remove moisture.

< Example  6> Vegetable of the second liquid sprayed on the steel pipe Polyol  Preparation: 3 - ((2- Hydroxyethoxy ) Carbonyl) acrylic acid

1) 100 g (1 eq) of maleic anhydride is placed in a 500 ml beaker, and 63.3 g (1 eq) of ethylene glycol is added thereto, followed by gradually heating to 60 ° C.

2) When the maleic anhydride starts to melt, the temperature rises. When it melts, the temperature rises to about 90 ℃. The reaction is terminated when the temperature falls again to 60 ° C. If the temperature rises above 100 ° C, impurities may be generated.

< Example  7> Vegetable of the second liquid sprayed on the steel pipe Polyol  Preparation: 3 - ((2,3- Dihydroxypropoxy ) Carbonyl) acrylic acid

1) 100 g (1 eq) of maleic anhydride is placed in a 500 ml beaker, and 93.9 g (1 eq) of glycerol is added, followed by gradually heating to 60 ° C.

2) When the maleic anhydride starts to melt, the temperature rises. When it melts, the temperature rises to about 90 ℃. The reaction is terminated when the temperature falls again to 60 ° C. If the temperature rises above 100 ° C, it may cause impurities.

< Example  8> Vegetable of second liquid sprayed on steel pipe Polyol  Preparation: Ester Polyol

1) In a 2 L three-necked round flask, 500 ml of THF was added, and 261 g of 3 - ((2-hydroxyethoxy) carbonyl) acrylic acid obtained in Example 6 was added thereto to dissolve. 180 g of the epoxidized fatty acid methyl ester obtained in Example 4 And 9.8 g of maleic acid as an acid catalyst, and the temperature is raised to 75 ° C.

2) Allow the reaction to proceed for 4 hours and cool the reaction slowly.

3) Unreacted 3 - ((2-hydroxyethoxy) carbonyl) acrylic acid and THF to remove the reactants are extracted with methylene chloride and water. (2-hydroxyethoxy) carbonyl) acrylic acid was completely removed and the methylene chloride was completely removed by filtration under reduced pressure to obtain 344 g of a light brown liquid ester polyol (yield: 97%).

< Example  9> Vegetable of second liquid sprayed on steel pipe Polyol  Preparation: Ester Polyol

1) In a 2 L three-necked round flask, 500 ml of THF was added, and 320 g of the 3 - ((2,3-dihydroxypropoxy) carbonyl) acrylic acid obtained in Example 7 was added to dissolve the epoxy resin. 180 g of fatty acid methyl ester and 9.8 g of acidic acid maleic acid are added and the temperature is raised to 75 캜.

2) Allow the reaction to proceed for 4 hours and cool the reaction slowly.

3) To remove unreacted 3 - ((2,3-dihydroxypropoxy) carbonyl) acrylic acid and THF (Tetrahydrofuran), the reactants are extracted with methylene chloride and water. At this time, unreacted 3 - ((2,3-dihydroxypropoxy) carbonyl) acrylic acid was completely removed by extraction with water twice, and the methylene chloride was completely removed by filtration under reduced pressure to obtain 340 g of a light brown liquid ester polyol , Yield: 96%).

< Example  10 ~ 21> Manufacture of vegetable polyurethane coatings on environmentally friendly steel pipes

The modified polyol mixture derived from the vegetable oil used as the main component of the second solution which is the polyol portion is used as the methoxypolyol of Example 2, the hydroxylpolyol of Example 3, the hydroxyl fatty acid methyl ester of Example 5, the ester polyol of Example 8 , And the ester polyol of Example 9 were used in the composition ratios shown in Table 4 below, and the units are% by weight.

Manufacture of vegetable polyurethane coatings coated on environmentally friendly steel pipes Example 2 Example 3 Example 5 Example 8 Example 9 all
(weight%) Example 10 19 3 78 - - 100 Example 11 - 20 80 - - 100 Example 12 20 - 80 - - 100 Example 13 8 7 85 - - 100 Example 14 15 - 85 - - 100 Example 15 - 20 80 - - 100 Example 16 17 2 71 10 - 100 Example 17 15 2 63 20 - 100 Example 18 13 2 55 30 - 100 Example 19 17 2 71 - 10 100 Example 20 15 2 63 - 20 100 Example 21 13 2 55 - 30 100

The physicochemical properties of the modified polyol derived from vegetable oil of Examples 2, 3, 5, 8, and 9 shown in Table 4 and the modified polyol derived from vegetable oil of Examples 10 to 21 were analyzed and shown in Table 5.

Physicochemical Properties of Vegetable Polyurethane Coatings Coated on Environmentally Friendly Steel Pipes Density 20 ℃
(g / cm3) Viscosity
(cP) Acid value
(x10³)
(mgKOH / g) OH
(mgKOH /
g) Oxirane
Oxygen(%) Moisture content
(ppm) Nonvolatile matter
(%) Example 2 1.01218 4605 0.58 199.8 1.68 754 97.3 Example 3 1.04130 1800 0 250.1 0.5 942 98.2 Example 5 1.00488 1510 37.9 184.0 0.42 1396 95.0 Example 8 1.236 30720 138.7 202.7 0.0163 2001 97.3 Example 9 1.238 34140 127.5 376.7 0.0183 1564 92.9 Example 10 0.96697 1700 0 214.0 0.05 1838 95.4 Example 11 0.97183 1020 0 225.0 0.02 2216 97.3 Example 12 0.98101 627 4.7 219.7 0.20 1935 96.5 Example 13 0.99812 2485 5.0 221.8 0.99 1394 94.7 Example 14 1.00969 895 15.3 232.2 0.85 1354 95.0 Example 15 0.99479 1125 4.1 220.3 0.58 1576 95.0 Example 16 1.090 770 5.1 184.8 0.0181 1811 94.8 Example 17 1.122 820 13.7 194.1 0.0371 1859 95.0 Example 18 1.140 830 177.5 189.5 0.0197 1904 97.2 Example 19 1.088 760 3.9 185.0 0.0396 1129 96.4 Example 20 1.126 820 14.4 198.34 0.0524 1647 93.7 Example 21 1.142 910 16.5 202.90 0.0299 1934 95.5

Density: 25 ° C (g / cm³) - ISO 2811

Viscosity: 25 占 폚 (mPa 占 퐏) - (ISO 2555 RVDVII + spindle 21-12 rpm)

Acid value: mg KOH / g - ISO 660

OH: mg KOH / g - ISO 4326

Oxirane Oxygen:% - AOCS Official Method Cd 9-57

Moisture content: ppm - ISO 4317

< Example  22 to 24 and Comparative Example  1, 2>

In Table 6, the first liquid isocyanate prepolymer was prepared in the following composition components and composition ratios.

The composition and composition ratio of the isocyanate prepolymer as the first solution in the vegetable polyurethane paint coated on the environmentally friendly steel pipe The first sum Example
22 Example
23 Example
24 Comparative Example
One Comparative Example
2 Monomelic MDI 62.50 - - - - Polymerizable MDI - 61.40 68.00 72.00 68.00 Low viscosity HDI trimmer 10.00 10.00 9.00 10.00 10.00 Petroleum-based polyether polyol (PP2000D) 27.50 28.60 23.00 - - The polyol mixture of Example 10 - - - 18.00 - The polyol mixture of Example 11 - - - - 22.00 Sum 100.00 100.00 100.00 100.00 100.00 Viscosity 85KU 95KU 88KU Very high Very high density 1.134 1.134 1.148 - - NCO wt% 22.14% 20.13% 22.53% 22.12% 20.00%

Details of the composition components of the first liquid isocyanate prepolymer prepared in Table 6 are shown in Tables 7 and 8 below.

Polyol Types of polyols ingredient OH equivalent Polyol PP2000D Petroleum-based polyether polyol 1000 Example 10 Modified polyol derived from vegetable oil 303.24 Example 11 Modified polyol derived from vegetable oil 273.66

Polyisocyanate Kinds ingredient NCO wt% Reactivity with polyol Polyisocyanate Polymerizable MDI MDI 31 Very fast Monomelic MDI MDI 33.6 speed Low viscosity HDI trimmer HDI 23 lateness

< Example  25 and 26> coated on environmentally friendly steel pipes 2-pack type  The second liquid of the vegetable polyurethane paint Of polyol  Produce

Table 9 shows compositional components and composition ratios of the second liquid vegetable polyol portion.

The composition and composition ratio of the vegetable polyol portion Second sum Example 25 Example 26 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Petroleum-based polyether polyol (PP-2000D) - - 15.00 - - 15.00 The polyol mixture of Example 10 15.00 - - 15.00 - - The polyol mixture of Example 11 - 15.00 - - 15.00 - Pigment (CR-828) 6.00 6.00 6.00 6.00 6.00 6.00 Dispersant 0.50 0.50 0.50 0.50 0.50 0.50 Defoamer 0.50 0.50 0.50 0.50 0.50 0.50 Desiccant 7.00 7.00 7.00 7.00 7.00 7.00 Petroleum-based polyether polyol (PP-2000D) - - 41.00 - - 46.00 The polyol mixture of Example 10 31.00 - - 41.00 - - The polyol mixture of Example 11 - 31.00 - - 41.00 - Aromatic primary amine - - - - - 25.00 Aromatic secondary amine 20.00 20.00 - - - - Tetrahydroxypolyol tertiary amine 20.00 20.00 - - - - Tetrahydroxypolyol - - - 30.00 30.00 - Petroleum-based polyether polyol (GP-400) - - 30.00 - - - Sum (wt%) 100.00 100.00 100.00 100.00 100.00 100.00

The polyol of the second liquid is a main component of the two-pack type vegetable polyurethane paint of the present invention, and is composed of a polymer polyol portion occupying the largest amount of the second liquid, a cross-linking agent (chain extender), and other additives such as a hygroscopic agent, And the like.

Specific details of the polyol, the crosslinking agent and the additive of the second solution are shown in Tables 10 and 11 and Table 12.

Cross-linking agent (chain extender) Kinds OH or amine equivalent

Cross-linking agent (chain extender)
Aromatic primary amine 89.1 Aromatic secondary amine 155.0 Tetrahydroxypolyol tertiary amine 73.1 Tetrahydroxypolyol 70.1 Petroleum-based polyether polyol (GP-400) 140.3

Polyol Kinds ingredient OH equivalent


Polyol PP2000D Petroleum-based polyether 1000 GP3000 Petroleum-based polyether 1000 Example 10 Modified polyol derived from vegetable oil 303.24 Example 11 Modified polyol derived from vegetable oil 273.66 Example 12 Modified polyol derived from vegetable oil 255.31 Example 13 Modified polyol derived from vegetable oil 222.77 Example 14 Modified polyol derived from vegetable oil 198.77 Example 15 Modified polyol derived from vegetable oil 224.09

Additive types and ingredients Kinds ingredient


Pigment CR-828 TiO ₂ MA-100 Carbon black PANAX Blue 2500 Organic pigment PANAX Green 3500 Organic pigment N Red F5RK Organic pigment Ideal Yellow Y42G Inorganic pigments Panax I.O. Red 3000 Inorganic pigments Dispersant BYK 180 Ammonium salt Defoamer BYK 1790 silicon Desiccant Molecular Sieve Al-silicate

In Examples 25 and 26 and Comparative Examples 3 to 6, polyols and polyamines were used as crosslinking agents, and the types and reactivity of these crosslinking agents are shown in Table 1.

< Example  27 and 28 Comparative Example  7 to 10> 2-pack type  Eco-friendly steel pipe coated with vegetable polyurethane paint

The first liquid of the isocyanate prepolymer of Examples 22 and 23 and the second liquid of the polyol portion of Examples 25 and 26 and Comparative Examples 3 to 6 were combined as shown in Table 13 and the two- The mixture was mixed in the same amount and sprayed on a steel pipe, and then the gelation time and surface condition of the coating film were evaluated.

Evaluation of eco-friendly steel pipes coated with two-component vegetable polyurethane paint Two-component vegetable
Polyurethane paint Example
27 Example
28 Comparative Example
7 Comparative Example
8 Comparative Example
9 Comparative Example
10 The isocyanate prepolymer (first liquid) Example 23 Example 23 Example 22 Example 23 Example 23 Example 22 Polyol portion
(Second solution) Example 25 Example 26 Comparative Example
3 Comparative Example
4 Comparative Example
5 Comparative Example
6 NCO wt% 20.13% 20.13% 21.14% 20.13% 20.13% 21.14% Gel time 38s 40s 30s 25s 25s 30s Surface condition Extremely
Good Extremely
Good bubble
Occur Bubble slightly Bubble slightly Heterogeneous reaction

In Comparative Examples 8, 9 and 10, bubbles were generated on the surface or the reaction was not uniform. This is because bubbles are generated by the water during the reaction between the first liquid and the second liquid polyol of the vegetable polyurethane paint using the monofunctional MDI as the first liquid. When only the monomodal MDI is used as the first liquid, It is confirmed that the reaction with moisture is minimized and can not be effectively suppressed.

On the other hand, in Examples 27 and 28 using the polymerizable MDI as the first liquid and using the tetrafunctional tertiary amine polyol and the aromatic secondary amine crosslinking agent exhibiting the stable reactivity identified in Table 1, bubbling occurred on the surface of the steel pipe To form a smooth coating film.

< Example  29 to 33 > 2-pack type  The second liquid of the vegetable polyurethane paint Of polyol  Produce

In Table 14, a second liquid polyol portion was prepared with the following composition components and composition ratios.

The composition and composition ratio of the second liquid polyol portion Second sum Example 29 Example 30 Example 31 Example 32 Example 33 Aromatic secondary amine 10.00 15.00 15.00 15.00 15.00 Pigment 6.00 3.00 3.00 3.00 3.00 Dispersant 0.50 0.30 0.30 0.30 0.30 Defoamer 0.50 0.30 0.30 0.30 0.30 Desiccant 7.00 5.00 5.00 5.00 5.00 Example 10 49.50 - - - - Example 12 - 54.60 - - 31.00 Example 13 57.60 - - Example 14 - - - - 60.60 Example 15 - - - 57.60 - Tetrahydroxypolyol tertiary amine 26.00 21.00 18.00 18.00 15.00 DBTDL1 - 0.50 0.50 0.50 0.50 BYK-1790 0.50 0.30 0.30 0.30 0.30 Sum 100.00 100.00 100.00 100.00 100.00

In Examples 29 to 33, the first liquid of Example 24 in which the NCO content was increased and the cross-linking between the polyol and isocyanate was improved, the Example 29 in which the content of the cross-linking agent was increased, the content of the cross- In order to increase the content, the paints having different colors were prepared by using Examples 12, 13, 14 and 15, respectively, in which the OH content was higher than in Examples 10 and 11.

In Examples 30 to 33, a small amount of DBTDL, a urethane curing catalyst, was used in order to control the increase of the polyol crosslinking agent content and the curing time to be longer than that of the aromatic secondary amine crosslinking agent.

< Example  34 to 38> 2-pack type  Eco-friendly steel pipe coated with vegetable polyurethane paint

The first liquid of the isocyanate prepolymer of Example 24 and the second liquid of the polyol portion of Examples 29 to 33 were combined as shown in Table 15 and sprayed using the two-component mixed impingement spray apparatus (USA, Graco Reactor XP-2) 1: 1, and then the gelation time and the surface state of the coating film were evaluated.

Evaluation of eco-friendly steel pipes coated with two-component vegetable polyurethane paint Two-component vegetable polyurethane paint Example 34 Example 35 Example 36 Example 37 Example 38 The isocyanate prepolymer (first liquid) Example 24 Example 24 Example 24 Example 24 Example 24 The polyol portion (second liquid) Example 29 Example 30 Example 31 Example 32 Example 33 NCO wt% 22.50% 22.50% 22.50% 22.50% 22.50% Gel time 1m18s 25s 25s 25s 25s Tack free time 10m 2m 2m 2m 2m Surface condition Good Very good Very good Very good Very good

The coating films of Examples 34 to 38 were all good in Table 15, and in Examples 35 to 38 using the polyurethane curing accelerator DBTDL, the gelation time was about 1/3 and the contact time was Which is about 1/5.

Table 16 shows the adhesion of the vegetable oil-derived modified polyols of Examples 27 and 28 and Examples 34 to 38 when the vegetable polyurethane paint was coated on the surface of the steel pipe. ASTM D 4541 was used to test the adhesion of the coating. As a test device, Pioitest AT adhesion tester from Delfelsko was used. The adhesive was Araldite 2011 from Huntsman, a two-component epoxy adhesive. The surface of the coated film is polished with a sandpaper to remove foreign substances on the surface, and the above-mentioned adhesive is applied, and a dolly is adhered thereon to cure the coated film. Thereafter, the dolly is pulled vertically upward, The force was measured.

Evaluation of adhesion of environmentally friendly steel pipe Example 27 Example 28 Example 34 Example 35 Example 36 Example 37 Example 38 Of the second solution
Polyol Example 10 Example 11 Example 10 Example 12 Example 13 Example 14 Example 15 Adhesion (psi) 1143 1089 1621 661 796 895 530 1589 1296 2073 868 797 497 535

Examples 27 and 28 use the first liquid isocyanate prepolymer of Example 23 with an NCO content of 20.13 wt%, with an adherence of at least 1000 psi. Example 34 using the first liquid of Example 24 having an NCO content of about 2% higher improved the adhesion force by 500 psi, but Examples 35 to 38 using the same first liquid of Example 24 were rather less adherent. This is because the reaction time is reduced by using the catalyst to minimize the reaction with moisture, and the coating film is formed smoothly. However, it is judged that the adhesion ability of the surface of the steel pipe is deteriorated because it does not have sufficient wetting time. In order to form an ideal coating film on the surface of a steel pipe, a suitable wetting time in addition to the reaction rate should be considered.

Table 17 shows the results of a test according to ASTM D 4060 for the wear resistance of steel tubes coated with vegetable polyurethane coating compositions containing modified polyols derived from vegetable oils of Examples 27 and 28 and Examples 34 to 38. Weights of 500g were attached to both sides of the test specimens. The coated test specimens were cut into 11cm lengthwise and 11cm lengths, and the test pieces were cleaned by drilling a hole in the center. Then, the electronic weights were measured to 0.0001g. The weight was measured and the difference was evaluated as abrasion resistance. The Taber Abrasion Tester from Yasuda was used for the abrasion resistance test and Calibrase CS-17 from Taber was used as the abrasive.

Wear resistance test results of environmentally friendly steel pipes Example 27 Example 28 Example 34 Example 35 Example 36 Example 37 Example 38 The polyol type of the second solution Example 10 Example 11 Example 10 Example 12 Example 13 Example 15 Example 14 Abrasion resistance (mg) 90.0 52.8 39.7 39.9 47.7 48.3 46.0

Examples 34 and 35 of Table 17 show excellent abrasion resistance of 40 mg or less, and the higher the NCO content, the greater the hardness and the improved abrasion resistance.

In Table 18, the hardness of the environmentally friendly steel pipe surface coating film formed from the vegetable polyurethane coating composition containing the modified polyols derived from the vegetable oil of Examples 27 and 28 and Examples 34 to 38 was measured according to ASTM D 2240. The hardness of the film was measured by the Durometer hardness tester D type of Telock.

Hardness measurement result of environmentally friendly steel pipe Example 27 Example 28 Example 34 Example 35 Example 36 Example 37 Example 38 The polyol type of the second solution Example 10 Example 11 Example 10 Example 12 Example 13 Example 15 Example 14 Durometer hardness 72D 73D 75D 74D 78D 77D 74D

All of Examples 27 to 38 of Table 18 show a coating film hardness of 70D or more. This shows that the higher the NCO content, the lower the molecular weight of the polyol, the greater the hardness.

In Table 19, the chemical resistance of the steel pipe surface coating film coated with the vegetable polyurethane coating composition including the modified polyols derived from the vegetable oil of Examples 27 and 28 and Examples 34 to 38 was tested according to ASTM D 543. The chemical resistance evaluation is to measure the resistance to chemical solvents. After the steel tube test piece with the completely dried coating film is washed, dried and measured for its weight, it is immersed in the chemical to be tested for a certain period of time, And then dried thoroughly, and the chemical resistance is evaluated by measuring the change in the weight and hardness of the above-mentioned steel pipe test piece.

Chemical resistance (chemical resistance) evaluation result of environmentally friendly steel pipe Chemical resistance Example 27 Example 28 Example 34 Example 35 Example 36 Example 37 Example 38 10% H ₂ SO ₄
(About 30 days) Weight change + 2.546% + 2.532% + 1.578% + 1.624% + 1.439% + 1.398% + 1.624% Change in hardness -2D -4D -3D -4D -3D -4D -4D 30% NaOH
(About 30 days) Weight change -0.160% -0.111% -0.089% -0.107% -0.131% -0.101% -0.080% Change in hardness 0D + 1D 0D + 1D 0D + 1D + 1D 30% NaCl
(About 30 days) Weight change + 0.091% + 0.172% + 0.065% + 0.102% + 0.128% + 0.099% + 0.069% Change in hardness 0D 0D 0D 0D 0D 0D 0D Diesel oil
(About 30 days) Weight change + 1.456% + 1.589% + 1.389% + 1.230% + 1.650% + 1.781% + 1.391% Change in hardness 0D -4D -2D -1D -2D -2D -2D

In general, polyurethane coatings are the most vulnerable in acidic solutions. As shown in Table 19, in Example 27, the weight increased and the hardness decreased in the sulfuric acid solution. However, in Examples 34 to 38 in which the NCO content was increased to improve the degree of crosslinking, the weight was slightly increased within 1 to 2% by weight, and there was almost no change in the alkaline solution and the aqueous salt solution. There was no big change. Accordingly, it is considered that the environmentally friendly steel pipe coated with the vegetable polyurethane paint according to the present invention has excellent alkali resistance and flame resistance.

Table 20 shows the coating state of the eco-friendly steel pipe coated with the two-pack type vegetable polyurethane paint of Examples 27 and 28 and Examples 34 to 38 described above.

Manufacture of eco-friendly steel pipes coated with two-component vegetable polyurethane paint varnish
(1 + 2 liquid) Example
27 Example
28 Example
34 Example
35 Example
36 Example
37 Example
38 The first sum Example
23 Example
23 Example
24 Example
24 Example
24 Example
24 Example
24 Second sum Example
25 Example
26 Example
29 Example
30 Example
31 Example
32 Example
33 In the second subset
Polyol Example
10 Example
11 Example
10 Example
12 Example
13 Example
15 Example
14 Viscosity 105KU 102KU 110KU 91KU 112KU 94KU 101KU importance 1.063 1.065 1.054 1.028 1.029 1.028 1.027 Gel time 38s 40s 1m18s 25s 25s 25s 25s Dry touch
time 5m 3m 10m 2m 2m 2m 2m Surface condition Extremely
Good Extremely
Good Good Extremely
Good Extremely
Good Extremely
Good Extremely
Good

Except for Examples 34 and 38 in Examples 27 and 28 and Examples 34 to 38, an excellent surface state was observed, and it was confirmed that the entire surface was good.

Table 21 summarizes the test results of eco-friendly steel tubes coated with the two-pack type vegetable polyurethane paint of Examples 27 and 28 and Examples 34 to 38, respectively.

Test result of environmentally friendly steel pipe Example 27 Example 28 Example 34 Example 35 Example 36 Example 37 Example 38 The type of polyol in the second liquid Example 10 Example 11 Example 10 Example 12 Example 13 Example 15 Example 14 Gel time 38s 40s 1m18s 25s 25s 25s 25s Touch dry time 4m 4m 10m 2m 2m 2m 2m Vegetable polyol content 23% 23% 24.75% 27.3% 28.8% 28.8% 30.3% Adhesion to steel 1143 psi 1089 psi 1621 psi 661 psi 796 psi 530 psi 859 psi 1589 psi 1296 psi 2073 psi 868 psi 797 psi 535 psi 497 psi flexibility OK OK OK OK OK OK OK Impact resistance OK OK OK OK OK OK offshoot
slightly Abrasion resistance 90.0 mg 52.8 mg 39.7 mg 39.9 mg 47.7 mg 48.3 mg 46.0 mg Durometer hardness 72D 73D 75D 74D 78D 77D 74D Chemical resistance 10% H2SO4
(30 days passed) Weight change + 2.546% + 2.532% + 1.578% + 1.624% + 1.439% + 1.398% + 1.624% Change in hardness -2D -4D -3D -4D -3D -4D -4D 30% NaOH
(30 days passed) Weight change -0.160% -0.111% -0.089% -0.107% -0.131% -0.101% -0.080% Change in hardness 0D + 1D 0D + 1D 0D + 1D + 1D 30% NaCl
(30 days passed) Weight change + 0.091% + 0.172% + 0.065% + 0.102% + 0.128% + 0.099% + 0.069% Change in hardness 0D 0D 0D 0D 0D 0D 0D Diesel oil
(30 days passed) Weight change + 1.456% + 1.589% + 1.389% + 1.230% + 1.650% + 1.781% + 1.391% Change in hardness 0D -4D -2D -1D -2D -2D -2D

The flexibility of the environmentally friendly steel pipes included in Table 21 was carried out in accordance with ASTM D 622, and the method is as follows. The coating film was completely cured and dried and then evaluated for resistance to cracking or peeling by bending using a conical mandrel or a cylindrical mandrel. All of the coating films of the coating compositions of the above examples were evaluated for bending flexural The test showed sufficient flexibility not to show any defects such as cracks and dropouts after bending.

The impact resistance of the environmentally friendly steel pipe included in Table 21 was performed in accordance with ASTM D 2794, and the method is as follows. In the test method, a weight of 1 kg was dropped at a height of 50 cm and evaluated by observing cracking or peeling of the impacted portion. The coating films formed by Examples 27 and 28 and Examples 34 to 37 had sufficient flexibility and flexibility so that there was no breakage, detachment, or cracking of the coating film. In Example 38, however, slight cracks appear. This is because the equivalence of the modified polyol derived from vegetable oil used in Example 38 is lower than the equivalent of other modified polyols derived from vegetable oil and has a low molecular weight of 198.77 and a relatively small molecular weight so that it does not have sufficient flexibility to withstand impact (See Table 11)

From the results shown in Table 21, it can be seen that the second liquid vegetable polyol of the two-pack type vegetable polyurethane coating coated on the environmentally friendly steel pipe is much less reactive with moisture than the petroleum-based polyether polyol in view of reactivity with MDI, It proved to be able to obtain a good ideal coating. It has also been found that the vegetable polyol is more stable and less sensitive to moisture than the monomeric MDI in the reaction with polymeric MDI. The vegetable polyol can form an ideal coating film when a specific crosslinking agent, specifically, an aromatic secondary amine and a tetrafunctional polyol tertiary amine, especially a tetrahydroxypolyol tertiary amine, is used, and a two-part plant poly The urethane paint can be coated with a solventless paint without using a solvent by using the above specific coating equipment. When the NCO content of the isocyanate prepolymer is designed to be in the range of 22 to 23% by weight and sprayed, the adhesion, abrasion resistance, hardness, An environmentally friendly steel pipe with better chemical resistance can be obtained.

Specifically, Example 34 is coated using the vegetable polyol mixture of Example 10, having a gelling time of 1 minute 18 seconds, an adhesion force of at least 1600 psi, and a hardness of 75 D. It has excellent flexibility and impact resistance, and has excellent wear resistance and chemical resistance.

In addition, Examples 35 to 38 form a very ideal coating film surface because the gelling rate is controlled using a catalyst to give a sufficient wetting time to the steel pipe surface.

< Example  39 to 44 > 2-pack type  The second liquid of the vegetable polyurethane paint Of polyol  Produce

In Table 22, in order to precisely grasp the reactivity between the polyol of the second liquid and the isocyanate of the first liquid, the modified polyol mixture derived from the vegetable oil, the crosslinking agent and the additive were all used in the same amount, To make them color-coded. On the other hand, the use of DBTDL, the most effective catalyst for the urethane reaction, was ruled out. The reason for this is that the use of DBTDL has the advantage of shortening the tack-free drying time with a quick reaction, but it has a disadvantage in that the wetting time of the steel pipe is not enough and the adhesion force is further lowered. The second liquid is designed to be the same amount as the first liquid isocyanate, and in particular, the reaction volume equivalents should be the same.

In Table 22, the equivalents of the respective components are obtained, and they are all divided by the amount to be used per 100 g of each component, and the hydroxyl group equivalent per 100 g of the paint is obtained. When this is converted to the specific gravity of the whole coating, the equivalence of the hydroxyl group contained in 100 ml of the coating can be obtained and expressed as the specific gravity equivalent.

The composition and composition ratio of the second liquid polyol portion of the two-pack vegetable polyurethane paint coated on the environmentally friendly steel pipe Second sum equivalent weight importance Example 39 Example 40 Example 41 Example 42 Example 43 Example 44 Secondary amine 155.0 1.08 20.00 20.00 20.00 20.00 20.00 20.00 Pigment 0.0 4.00 6.00 6.00 6.00 6.00 6.00 6.00 Dispersant 0.0 1.07 0.30 0.30 0.30 0.30 0.30 0.30 Defoamer 0.0 0.85 0.30 0.30 0.30 0.30 0.30 0.30 Desiccant 0.0 1.10 5.00 5.00 5.00 5.00 5.00 5.00 Example 16 330.9 0.97 42.10 - - - - - Example 17 350.3 0.97 - 42.10 - - - - Example 18 369.6 0.97 42.10 - - - Example 19 325.0 0.97 - - - 42.10 - - Example 20 334.5 0.97 - - - - 42.10 - Example 21 344.0 0.97 - - - - - 42.10 Tertiary amine 73.1 22.00 22.00 22.00 22.00 22.00 22.00 22.00 Defoamer 0.0 0.30 0.30 0.30 0.30 0.30 0.30 0.30 stabilizator 0.0 4.00 4.00 4.00 4.00 4.00 4.00 4.00 Sum 100.00 100.00 100.00 100.00 100.00 100.00 Equivalent of second solution - - 0.5655 0.5597 0.5545 0.6102 0.6069 0.5545 Specific gravity of second solution - - 1.075 1.075 1.075 1.075 1.075 1.075 Equivalent weight equivalent - - 0.6082 0.6019 0.5962 0.6082 0.6019 0.6038 Viscosity of the second liquid - - 95KU 101KU 107KU 98KU 103KU 109KU

The secondary amine is an aromatic secondary amine, the tertiary amine is a tetrahydroxypolyol tertiary amine and the stabilizer is triethyl orthoformiate. Specific details of the polyols of Examples 16 to 21 used in the preparation of the second solution of Table 22 are shown in Table 23. [

Modified polyol derived from vegetable oil Polyol Molecular Weight Average molecular weight OH number Number of COOH OH equivalent

) Formula 4
(R =

) 526 526 1.9 1.3 276.8 Formula 4
(R =

) 565.57 566 3.8 1.3 148.9 Example 16 900 ~ 920 910 3.0 0.05 303.3 Example 17 840 to 860 850 2.9 0.2 293.1 Example 18 840 to 860 850 2.9 0.2 293.1 Example 19 900 ~ 920 910 3.0 0.05 303.3 Example 20 850-870 860 3.0 0.2 286.7 Example 21 850-870 860 3.1 0.2 277.4

In Table 23, the polyol of formula (4) has a high viscosity at room temperature and solidifies at a low temperature. In Examples 16 to 21, the polyol of Chemical Formula 4 is mixed with other modified polyols derived from vegetable oils to have a low viscosity. The polyol mixtures are sufficiently usable at room temperature and have an appropriate molecular weight. This was calculated by calculating the hydroxyl group equivalent.

On the other hand, the equivalent weight-equivalent equivalent of the isocyanate prepolymer of Example 24 is shown in Table 24 as the first solution.

The first liquid isocyanate prepolymer The first sum Example 24 NCO content (wt.%) 22.50% Paint equivalent 186.6 Paint specific gravity 1.146 Equivalent weight equivalent 0.6138 Viscosity 88.3KU

< Example  45 to 50> 2-pack type  Eco-friendly steel pipe coated with vegetable polyurethane paint

 The first liquid of the isocyanate prepolymer of Example 24 and the second liquid of the polyol portion of Examples 39 to 44 were mixed in a two-component mixed impingement spray apparatus (USA, Graco Reactor XP-2 ), And then the gelling time and the surface state of the coating film were evaluated. The ratio of the equivalent weight conversion equivalent (see Table 24) of the isocyanate prepolymer as the first solution to the specific gravity conversion equivalent weight (see Table 22) of the polyol portion as the second solution was found to be 1.01 to 1.03, When the composition is consumed equally at a volume ratio of 1: 1, it can be seen that the equivalence of the isocyanate moiety is slightly more than 0.01 to 0.02, and it is found that the iso-mixed ratio of 1: 1 volume is the most ideal ratio.

Evaluation of Eco-Friendly Steel Pipes Coated with Two-Component Vegetable Polyurethane Coatings Two-component vegetable
Polyurethane paint Example
45 Example
46 Example
47 Example
48 Example
49 Example 50 Prepolymer
(First solution) Example
24 Example
24 Example
24 Example
24 Example
24 Example 24 The polyol (second liquid) Example
39 Example
40 Example
41 Example
42 Example
43 Example 44 NCO wt% 22.50% 22.50% 22.50% 22.50% 22.50% 22.50% NCO / OH (vol) 1.01 1.02 1.03 1.01 1.01 1.02 Gel time 58s 58s 58s 58s 58s 58s Touch dry time 2m16s 2m16s 2m16s 2m16s 2m16s 2m16s

The adhesion of the coating film formed from the plant polyurethane coating composition containing the modified polyol derived from vegetable oil of Examples 45 to 50 in Table 25 was tested according to ASTM D 4541. The testing apparatus was a Pioitest AT adhesion tester was used. The adhesive was Araldite 2011 of Huntsman, a two-component epoxy adhesive. The surface of the coated film is polished with a sandpaper to remove foreign substances on the surface, and the above-mentioned adhesive is applied, and a dolly is adhered thereon to cure the coated film. Thereafter, the dolly is pulled vertically upward, The force was measured. The evaluation results are shown in Table 26.

Evaluation of adhesion of environmentally friendly steel pipe Example 45 Example 46 Example 47 Example 48 Example 49 Example 50 The second liquid polyol Example 16 Example 18 Example 19 Example 21 Example 17 Example 20 Adhesion to steel (psi) 1855 883 1968 853 1570 1674

The coating compositions of Examples 45, 47, 49 and 50, in which the polyol mixture in the second liquid was changed to Examples 16, 17, 19 and 20, were given a sufficient gelling time so that the adhesion to steel was all above 1500 psi However, in the case of Examples 46 and 48 using Examples 18 and 21, the adhesion was lowered to 1000 psi or less. This means that the wetting time of the steel tube is sufficient but the tensile strength of the film is lower than the reference value having sufficient adhesion, and eventually the film is broken at 883 and 853 psi.

The abrasion resistance of the coating films formed from the vegetable oil-derived modified polyols of Examples 45 to 50 was evaluated in accordance with ASTM D 4060 in the same manner and under the same conditions as in Table 17, Respectively.

Wear resistance test results of environmentally friendly steel pipes Example
45 Example
46 Example
47 Example
48 Example
49 Example
50 The polyol type of the second solution Example
16 Example
18 Example
19 Example
21 Example
17 Example
20 Abrasion resistance (mg) 15.9 14.9 14.2 8.6 10.8 15.2

Examples 45 to 50 all have excellent abrasion resistance irrespective of the kind of the second liquid polyol. The difference of 5 mg shown in Table 26 is evaluated as a simple error and does not have a different meaning when the value is less than 20 mg.

Table 28 shows the hardness of the coating films coated with the vegetable polyurethane coating materials containing the modified polyols derived from the vegetable oil of Examples 45 to 50 according to ASTM D 2240 under the same conditions and conditions as those in Table 18. [

Hardness measurement result of environmentally friendly steel pipe Example 45 Example 46 Example 47 Example 48 Example 49 Example 50 The polyol type of the second solution Example 16 Example 18 Example 19 Example 21 Example 17 Example 20 Durometer hardness 73D 72D 73D 75D 77D 72D

All of the coating film hardnesses are not less than 70 D, and particularly excellent regardless of the kind of the polyol in the second liquid used.

In Table 29, the chemical resistance of the coating film coated with the vegetable polyurethane coating composition containing 45 to 50 modified polyols derived from vegetable oil was carried out according to ASTM D 543 in the same manner and under the same conditions as in Table 19 described above.

Evaluation of chemical resistance (chemical resistance) of environmentally friendly steel pipe Chemical resistance Example 45 Example 46 Example 47 Example 48 Example 49 Example 50 10% H ₂ SO ₄
(30 days passed) Initial weight (g) 3.6054 3.8841 4.1702 2.3053 3.3756 2.8911 Weight after experiment (g) 3.6480 3.9392 4.2171 2.3535 3.4412 2.9385 Weight change rate (%) 1.18 1.42 1.12 2.09 1.94 1.64 Change in hardness -2D -3D -2D -4D -3D -3D 30% NaOH
(30 days passed) Initial weight (g) 3.4877 3.9104 3.9968 2.2778 3.0014 3.0552 Weight after experiment (g) 3.4941 3.9191 4.0042 2.2791 3.0049 3.0587 Weight change rate (%) 0.18 0.22 0.19 0.06 0.12 0.11 Change in hardness 0D 0D 0D 0D 0D 0D 30% NaCl
(30 days passed) Initial weight (g) 3.4362 3.8559 3.8747 2.3837 3.1764 3.5945 Weight after experiment (g) 3.4519 3.8785 3.9001 2.3955 3.1860 3.6065 Weight change rate (%) 0.46 0.59 0.66 0.50 0.62 0.63 Change in hardness 0D 0D 0D 0D 0D 0D Diesel oil
(30 days passed) Initial weight (g) 3.6541 3.9186 3.8747 2.3837 3.0572 2.9021 Weight after experiment (g) 3.6700 3.9253 3.8842 2.3851 3.0741 2.9133 Weight change rate (%) 0.44 0.17 0.25 0.06 0.55 0.39 Change in hardness -4D -2D -2D -2D -3D -2D

As can be seen from Table 29, the polyurethane coating showed no significant change in weight and hardness among the remaining chemicals except the acidic solution. In the acid resistance test in the acid solution, the rate of change was less than 5%, and it was evaluated to have comparatively excellent acid resistance.

Flexibility of steel pipe coatings coated with vegetable polyurethane coatings containing modified polyols derived from vegetable oils of Examples 45 to 50 was carried out by Mandrel bend tester of Gardner in accordance with ASTM D 622. [ Except for Example 46 and Example 48, all of them showed sufficient flexibility in a 180 ° bending flexural test, and no cracks or dropouts of the coating film after bending were observed. In the case of Example 46 and Example 48, it was found that there was a close relationship with the cause of the above-mentioned decrease in the adhesion, and the modified polyol derived from the vegetable oil did not sufficiently react with the crosslinking reaction to form a three-dimensional structure due to crosslinking after curing .

The impact resistance of the coating films coated with the vegetable oil-derived modified polyol-containing vegetable oil-based polyurethane coating compositions of Examples 45 to 50 was evaluated in accordance with ASTM D 2794 as shown in Table 20 described above. In all the examples, there was no breakage or detachment of the coating film or occurrence of cracking, and this was also the same in the coating films of Example 46 and Example 48 which were evaluated as insufficient in flexibility.

< Example  Coated steel pipe 2-pack type  The first liquid isocyanate of the vegetable polyurethane paint Prepolymer  Produce

The first liquid isocyanate prepolymer sprayed on the environmentally friendly steel pipe is produced using MDI instead of the generally used TDI (Toluene Diisocyanate), and the NCO content is kept high during the formation of the coating film of the environmentally friendly steel pipe. In the reaction of MDI with polyol, the NCO content reaches 20% by weight, whereas the reaction of TDI with polyol results in an NCO content of 4 to 10% by weight. If TDI is used, it may be harmful to human body due to remaining TDI without reacting with polyol. In the present invention, one liquid prepared by using MDI is sprayed. Table 30 shows the compositional components and composition ratios of the first liquid isocyanate prepolymer using the polymerizable MDI as the curing agent sprayed on the environmentally friendly steel pipe and the monomeric MDI.

The composition and composition ratio of the first liquid isocyanate prepolymer The first sum      Example 24 Example 51 Polymerizable MDI 68.00 - Monomelic MDI - 60.30 Low viscosity HDI trimmer 9.00 9.00 PP2000D 23.00 30.70 Sum 100.00 100.00 Viscosity 88KU 84.6KU density 1.148 1.143 NCO content (wt.%) 22.53% 22.50%

< Example  52 and Example  53> coated on environmentally friendly steel pipe 2-pack type  The second liquid of the vegetable polyurethane paint Of polyol  Produce

The secondary amine was dispersed with a crosslinking agent to disperse the pigment, and the polyols of Examples 10 and 16 were respectively added and stirred to prepare a polyol portion of the second solution with the composition components and composition ratios shown in Table 31. [

The composition and composition ratio of the second liquid polyol portion Second sum Example 52 Example 53 Aromatic secondary amine 22.00 15.00 Inorganic pigments 5.50 5.00 Organic pigment 0.50 1.00 Dispersant 0.30 0.30 Defoamer 0.30 0.30 Desiccant 5.00 5.00 Dispersed for 40 minutes The polyol mixture of Example 10 43.60 - The polyol mixture of Example 16 - 40.60 Alkylene oxide polyol - 10.00 Tetrahydroxypolyol tertiary amine 22.00 22.00 Defoamer 0.30 0.30 stabilizator 0.50 0.50 Sum 100.00 100.00 Viscosity 95.1KU 113.2KU Granularity 5 μm or less 5 μm or less Color separation none none importance 1.061 1.065

In Example 52, the amount of aromatic secondary amine was increased in order to disperse the pigment. In Example 53, an alkylene oxide polyol (GP-3000, KPX) was added to decrease the viscosity. The alkylene oxide polyol has low reactivity with the isocyanate curing agent and may cause coating failure due to swelling of the coating film due to reaction with moisture in the air, so that it is preferably added in an amount of 10 wt% or less.

< Example  54 to 56 > 2-pack type  Vegetable polyurethane paint

The first liquid containing the above-described second liquid of Example 52, the first liquid containing the monomeric MDI of Example 51, and the first liquid containing the polymerizable MDI of Example 24 were mixed and coated using the above-described coating apparatus These were Examples 54 and 55, respectively.

Further, the second solution of Example 53 and the first solution containing the monomelic MDI of Example 51 were mixed and coated using the coating apparatus described above, to prepare Example 56.

Table 32 shows the reactivity and reaction stability of the environmentally friendly steel tubes coated with the coating compositions of Examples 54 to 56.

Reactivity and reaction stability of environmentally friendly steel pipes Example 54
(Example 51 using the first liquid) Gelling
time 70 seconds reaction
stability Homogeneous reaction without clogging.
Flexible without bending during forced bending. Example 55
(Example 24 using the first liquid) Gelling
time 55 seconds reaction
stability Homogeneous reaction without clogging.
Breaking during forced flexion. Example 56
(Example 51 using the first liquid) Gelling
time 77 seconds reaction
stability Homogeneous reaction without clogging.
Flexible without bending during forced bending.

From the results in Table 32, it can be seen that when the first prepolymer of Example 24 containing the polymerizable MDI is used, the hardness of the coating film increases and the coating film breaks at the time of forced bending, whereas in Example 51 (Examples 54 and 55) The first liquid of the isocyanate prepolymer of Example 24 containing a polymerizable MDI contained mono-monomeric MDI. Was found to be faster than the first liquid of the isocyanate prepolymer of Example 51. [

On the other hand, it has been found that the surface state of the coating film is superior as the amount of the alkylene oxide polyol used is reduced.

Table 33 shows the results of evaluating whether or not environmentally friendly steel pipes coated with vegetable polyurethane coating compositions containing the modified polyol derived from vegetable oil of Example 45 are suitable as tap water pipes. The reference value is based on AWWA C222 Polyurethane coatings for the interior and exterior steel water pipes and fittings, USA standards. The drinking water quality test is based on the dissolution test of the liquid epoxy resin coating and coating method for drinking water in KS D 8502 water.

Reliability evaluation result and reference value of eco-friendly steel pipe Test Items Test result Reference value Test Specification One Bond strength 15.5 N / mm &lt; 2 &gt; (2248 psi) 1500 psi or more ASTM D 4541 2 flexibility 10 mm, no abnormality 100 mm, no more ASTM D 522 3 Impact 19.6 N.m (2 kg.m) 0.46 kg.m or more ASTM D 2794 4 Abrasion resistance 2 mg 100 mg or less ASTM D 4060 5 10% H ₂ SO ₄ (30 days) 0.4% Dimensional change rate, 5% or less ASTM D 543 1.3% Weight change rate, less than 5% 6 30% NaOH (30 days) 0.2% Dimensional change rate, 5% or less ASTM D 543 0.4% Weight change rate, less than 5% 7 30% NaCl (30 days) 0.2% Dimensional change rate, 5% or less ASTM D 543 0.6% Weight change rate, less than 5% 8 Diesel (30 days) 0.4% Dimensional change rate, 5% or less ASTM D 543 1.2% Weight change rate, less than 5% 9 Water absorption rate 0.3% 3% or less ASTM D 570 10 Hardness 86D 65D or more ASTM D 2240 11 Drinking water
Water quality process test method Suitable Must meet national standards KSD 8502 12 Cathodic peeling test Average peeling distance: 4.4 mm 12 mm or less ASTM G8 Maximum separation distance: 4.6 mm 13 Nonvolatile matter A part: 99.0% over 90 KS M ISO 3251 B part: 99.1%

Table 33 shows the results of evaluating whether the environmentally friendly steel pipe coated with the vegetable polyurethane coating composition containing the modified polyol derived from the vegetable oil of Example 45 is suitable as a waterproof coating, a water tank, a water treatment facility, a tunnel interior, etc. . In each of the items, environmental friendly steel pipes coated with vegetable coatings are shown in accordance with the respective test standards in terms of peeling of the coating film, reduction of coating film size due to fluid flowing inside the steel pipe, peeling of the negative electrode, and test method of drinking water quality .

Table 34 shows whether or not the environmentally friendly steel pipe according to the present invention is suitable as an inner coating agent of a heavy crude oil tank when used as an inner coating agent of a heavy crude oil tank, This is the result of evaluating the presence or absence of lifting of the coating film and the change in gloss and hardness of the coating film.

Evaluation of Eco-friendly Steel Pipes time Early 10 days 30 days 40 days 50 days 60 ° C /
60 days 60 ° C /
90 days 60 ° C / 150 days Polish 84 86 86 86 86 86 85 86 Hardness (D) 79 78 78 78 76 76 75 77 Surface blister - none none none none none none none

In Table 34, steel tube test specimens immersed in crude oil were taken out after a certain period of time, and the crude oil was cleanly removed with a soft cloth and left for 1 hour at room temperature. No swelling of the blister or film on the surface was found, and there was little change in gloss and hardness.

After the lapse of 50 days, there was no change in the state of the coating film, so the test conditions were changed to change to the immersion test at 60 ° C. After 60 days and 150 days at 60 ° C, there was no reduction in gloss or hardness, indicating that the resistance to crude oil was excellent.

As described above, the eco-friendly steel pipe coated with the vegetable paint of the present invention is excellent in the physical and chemical properties of the vegetable polyurethane paint, and can be used as a waterproofing material for general purpose water, seawater and plant pipes, crude oil tanks, It is an excellent product that can be used safely and prevent environmental pollution by using environmentally friendly vegetable paint.

Claims (11)

A first liquid as an isocyanate prepolymer composed of 18 to 34% by weight of a petroleum-based polyether polyol, 55 to 75% by weight of MDI (methylene diphenyldiisocyanate) and 7 to 11% by weight of HDI (hexamethylene diisocyanate) Spraying; And
A step of spraying the first liquid on the inner surface of the steel pipe, and a step of spraying the first liquid on the inner surface of the steel pipe with 30 to 70 wt% of modified polyol derived from vegetable oil, 8 to 25 wt% of aromatic secondary amine, To 30% by weight of a polyol and 8 to 15% by weight of an additive as a main component,
Wherein the first liquid and the second liquid mixed by injection of the first liquid and injection of the second liquid are dissolved in an amount such that the NCO (isocyanate) content is 20 to 23% by weight, Wherein the paint is a polyurethane paint. The method according to claim 1,
Wherein the step of spraying the first liquid onto the inner surface of the steel pipe and the step of spraying the second liquid are performed by equally injecting the first liquid and the second liquid on the inner surface of the steel pipe at a ratio of 1: Wherein the first liquid and the second liquid are coated on the inner surface of the steel pipe with the non-solvent two-pack type vegetable polyurethane paint, characterized in that the first liquid and the second liquid are impinged and mixed at a ratio of 1: Wherein the method comprises the steps of: The method according to claim 1,
Spraying the first liquid onto the inner surface of the steel pipe, spraying the second liquid, and injecting the first liquid onto the outer surface of the steel pipe; And
Further comprising the step of injecting the first liquid onto the inner surface of the steel pipe and injecting the second liquid onto the outer surface of the steel pipe at the same time as injecting the second liquid, Is sprayed onto the outer surface of the steel pipe at the same time. The method according to claim 1,
Coating a polyethylene paint on the outer surface of the steel pipe with a polyethylene paint comprising 1 to 30% by weight of a polyethylene resin, 1 to 20% by weight of a copolymer having an organic functional group and 50 to 98% by weight of a solvent, Wherein the method comprises the steps of: The method according to claim 1,
A first liquid as an isocyanate prepolymer of 45 to 60% by weight composed of 2,4-4,4-MDI or carbonate-modified MDI or derivatives thereof;
And a second liquid comprising 40 to 55% by weight of a polyether amine or a low molecular weight amine. Steel pipe; And
A first liquid as an isocyanate prepolymer coated on the inner surface of the steel pipe and comprising 18 to 34% by weight of a petroleum-based polyether polyol, 55 to 75% by weight of MDI (methylene diphenyldiisocyanate) and 7 to 11% by weight of HDI (hexamethylene diisocyanate) A polyol comprising as a main component 30 to 70% by weight of a modified polyol derived from vegetable oil, 8 to 25% by weight of an aromatic secondary amine, 10 to 30% by weight of a tetrafunctional tertiary amine polyol, and 8 to 15% A first inner surface coating layer which is a solvent-free two-pack type vegetable polyurethane paint containing a second liquid,
Wherein the solvent-free two-pack type vegetable polyurethane paint is contained in an amount such that the NCO (isocyanate) content of the mixed first liquid and the second liquid is 20 to 23% by weight. The method according to claim 6,
And a first outer coating layer coated on an outer surface of the steel pipe and being a solventless two-pack type vegetable polyurethane paint. The method according to claim 6,
And a first outer coating layer which is coated on the outer surface of the steel pipe and is a polyethylene paint comprising 1 to 30% by weight of a polyethylene resin, 1 to 20% by weight of a copolymer having an organic functional group and 50 to 98% by weight of a solvent Eco - friendly steel pipe. 9. The method of claim 8,
A second outer coating layer disposed between the outer surface of the steel pipe and the first outer coating layer and coated on the outer surface of the steel pipe and having modified polyethylene as an adhesive material,
Wherein the first outer coating layer is coated on the outer surface of the steel pipe coated with the second outer coating layer. 10. The method of claim 9,
Further comprising a third outer coating layer of a primer material disposed between the outer surface of the steel pipe and the outer surface coating layer and coated on the outer surface of the steel pipe,
Wherein the second outer coating layer is coated on the outer surface of the steel pipe coated with the third outer coating layer. The method according to claim 6,
A first liquid as an isocyanate prepolymer of 45 to 60% by weight composed of 2,4-4,4-MDI or carbonate-modified MDI or derivatives thereof;
40 to 55% by weight of a second liquid of polyetheramine or a low molecular weight amine; And a first outer coating layer which is a polyurea coating material containing a polyolefin resin.

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