WO2022030872A1 - Composite pipe and composite panel which have improved adhesive properties by using thermoplastic treatment of polyurea, and manufacturing methods therefor - Google Patents

Abstract

A method for manufacturing a composite pipe or a composite panel, according to the present invention, heats a polyurea layer to 180-320°C to plasticize a polyurea, and thus provides high adhesive strength and peel strength and forms an interfacial film on the outer surface and the surface, in contact with a material to be coated, of the polyurea layer, so that a moisture barrier property is improved and a relatively large number of pores are included in the polyurea layer, and thus elasticity and impact strength can be improved. In addition, the present invention comprises a composite pipe and a composite panel that are manufactured by the manufacturing method.

Description

Composite pipe, composite panel, and method for manufacturing the same with improved adhesive properties by using thermoplastic treatment of polyurea

The present invention relates to a method for manufacturing a composite pipe and a composite panel.

Specifically, (i) by heating the polyurea layer to 180 ~ 320 ℃ to plasticize the polyurea, it has high adhesion and peel strength, and an interfacial film is formed on the contact surface and the outer surface of the polyurea layer with the adherend to block moisture Since the properties are improved and the interior of the polyurea layer contains a relatively large number of voids, it is possible to manufacture a composite pipe and composite panel with improved elasticity and impact resistance,

(ii) The first and second tubes are heated and adhered, but a composite tube in which bubbles contained in the polyurea layer (adhesive layer) between the first and second tubes are removed due to the difference in the coefficient of thermal expansion of the first and second tubes can be manufactured It is about the manufacturing method.

In addition, the present invention also relates to a composite pipe and composite panel made by the above manufacturing method.

This application is based on Korean Patent Application No. 10-2020-0098229 (Title of the invention: Composite pipe, composite panel, and manufacturing method thereof with improved adhesive properties using thermoplastic treatment of polyurea. Filed on August 5, 2020) All contents included in the specification and drawings of Korean Patent Application No. 10-2020-0098229 are incorporated herein by reference.

In general, polyurea has excellent water absorption resistance, has a general operating temperature range (normally -45℃ ~ +80℃), is strong against heat and cold, is free from ambient temperature and humidity, has a very fast curing time from a few seconds to a few minutes, and has excellent water resistance. Because it is high, it is used as a waterproofing material in various fields, has excellent impact resistance, and is excellent in preventing corrosion of metal. In particular, the greatest advantage of polyurea is that it has excellent wear and chemical resistance and a very wide usable temperature.

And, unlike polyurethane, polyurea has excellent surface quality and higher environmental stability because it does not use a separate catalyst, release agent, solvent, or organometallic compound. In addition, while epoxy and polyurethane have high reactivity to water and temperature, polyurea has strong water resistance and almost no thermal deformation, excellent scratch resistance, light resistance, chemical resistance, and permanent resistance to UV rays. also have

Due to these polyurea stability and excellent properties, polyurea-coated steel pipe has been judged to be suitable for 48 item tests according to the American Water Association standard AWWA C 222 and the American National Sanitation Association NSF 61 drinking water standards. have.

Polyurea has the form of a divided block composite divided into microphases, and this form consists of hardened (hard segment) regions dispersed in a flexible (soft segment) matrix.

The hardened part is extensively hydrogen-bonded and functions by reversible physical crosslinking, so it exhibits excellent mechanical properties, especially impact resistance and robustness, and is very valuable as a protective coating material for clothes and metal materials. As a representative example, in the case of a coated steel pipe, the coating was applied to a thickness of at least 3 mm when coating 3-layer polyethylene, but polyurea has been known to express the performance of a coated steel pipe only with a coating of 0.63 mm thick.

However, as described above, polyurea has a very short curing time from a few seconds to a few minutes. In order to overcome this, the copolymerization monomers are sprayed and collided with high pressure at a temperature of 40 to 70 ° C. can be obtained, and thus there is a problem in use.

The spray-coated polyurea has very weak peel strength on the surface of the iron pipe. Therefore, when polyurea is applied to the surface of a metal tube or a metal panel, there is a problem in that the peel strength of the polyurea layer is very low.

In addition, there are a number of bubbles inside the polyurea layer, but there is a problem that moisture penetrates through the bubbles to corrode the metal tube or metal panel and cause layer separation.

Applicants have found that the above-mentioned problem arises because the wetting area is small due to adhesion by spray application and it does not go beyond the concept of bonding to the contact surface.

In addition, the present applicant knows that moisture that has penetrated for a long time through the air bubbles distributed in the coating layer according to the spray coating method may reach the interface between the adherend and the polyurea to gradually corrode the metal and cause layer separation accordingly. In order to prevent this, the current spray coating method is judged to be effective only when a minimum coating thickness of 3.0 mm or more, such as 3-layer polyethylene, is applied.

As above, polyurea is a very attractive and excellent coating material, but with the current spray coating method, only bonding with the metal to be adhered occurs, and due to the fast curing speed, sufficient wetting is not achieved, so the bonding performance is 100% It cannot be expressed, and a high value is shown in the Dolly Test, but the result is weak in peel strength.

The present invention has been proposed to solve the above-mentioned problems, and by heating the polyurea layer to 180 ~ 320 ℃ to plasticize the polyurea to have high adhesion and peel strength, and to have high adhesion and peel strength, and the contact surface of the polyurea layer with the adherend An object of the present invention is to provide a method for manufacturing a composite pipe or composite panel, which improves moisture barrier properties by forming an interfacial film on the outer surface and improves elasticity and impact resistance by allowing a relatively large number of pores to be included in the polyurea coating layer have.

Another object of the present invention is to combine through expansion and contraction by sequentially heating and cooling from one end to the other end of the first and second tubes using the difference in the coefficient of thermal expansion of the first and second tubes. An object of the present invention is to provide a method for manufacturing a composite pipe in which the adhesive properties (coupling force) between the first and second pipes are increased by removing air bubbles contained in the polyurea layer (adhesive layer) between the two pipes.

Another object of the present invention is to provide a composite pipe and composite panel made by the above manufacturing method.

As described above, polyurea can be applied by spraying copolymer monomers to the adherend at a high pressure at a temperature of 40 to 70 ° C. In this case, the peel strength on the surface of the metal tube or metal panel is very weak. has a problem.

As a result of studying this problem, the present applicant found out that since the monomers for copolymerization are applied by spraying, the wetting area is small and sufficient bonding is not achieved. That is, when polyurea is spray-applied, sufficient wetting is not performed due to a fast curing speed, and thus sufficient adhesive strength cannot be exhibited, which results in low peel strength, that is, low adhesive strength.

As shown in FIG. 1, as polyurea is sprayed and applied in the form of a fine powder, there is a space between the particles, and thus wetting cannot be expressed on the adherend, so the adhesion surface area is small and the sprayed surface area is small. It was identified as a phenomenon that occurs because the space between the powder particles acts as a void, further reducing the surface area of attachment with the adherend.

In addition, the space generated between the sprayed powder particles acts as a void in the coating film, and in the long term, these micropores act as a penetration path for moisture, which corrodes the adherend or causes layer separation between the adherend and the polyurea layer. .

The present invention has been devised to solve the above problems. The present invention provides a step of forming a polyurea layer on an adherend by spraying (S1) an aromatic diisocyanate and a linear aromatic or aliphatic amine having 3 or more linear carbon atoms, for example, a metal pipe, a metal panel, a pipe connecting part, etc.; and, (S2) heat-treating the polyurea layer.

The heat treatment is performed by spraying the aromatic diisocyanate and the amine to the adherend heated to a temperature at which plasticization occurs in step (S1), or by heating polyurea to a temperature at which plasticization occurs after step (S1). can be done A detailed explanation of this is as follows.

The aromatic diisocyanate and the amine may be sprayed in a conventional ratio used for polyurea coating, for example, 1:1 (volume ratio).

The polyurea according to the present invention is formed by polymerization of an aromatic diisocyanate and an aromatic or aliphatic amine having 3 or more linear carbon atoms. The polymerization reaction proceeds very quickly. When an aromatic diisocyanate and a straight-chain aromatic or aliphatic amine having 3 or more carbon atoms are simultaneously sprayed onto an adherend, the two monomers are polymerized on the adherend to form a polyurea layer. The aromatic amines may have 12 or more carbon atoms in the repeating unit.

Polyurea has a temperature range of -40°C to +80°C, but in reality, it maintains thermal stability from about 180°C to less than 230°C, and thermal stability is reduced from around 280°C to 320°C or less. In general, the upper limit of the operating temperature of polyurea is set to 80°C because the maximum temperature at which the physical properties are maintained is 120°C, and the breakage of hydrogen bonds usually starts around 62°C and most hydrogen bonds at 90°C or higher. This is because the separation indicates a weakening of physical rigidity, and the size of the pores increases and the appearance of the coated body becomes unstable. From about 180° C. to less than 230° C., the change in physical properties is not so great that it interferes with use, except for a decrease in physical properties due to loss of hydrogen bonds. In addition, since hydrogen bonding is reversible with temperature, when the temperature is lowered to room temperature, hydrogen bonding occurs again in the cooling process.

The polyurea formed by spraying the aromatic diisocyanate and the amine consists of a hardening part and a flexible part, the flexible part has 3 or more straight-chain carbon atoms, and the flexible part is plasticized according to the plasticization so that the polyurea is partially plasticized. can

The plasticization or flow of the flexible part (soft segment) can macroscopically appear as the flow of polyurea, and when this plasticized flow is adjusted in an appropriate temperature range, damage to the crosslinking of the hardened part (hard segment) is minimized and polyurea flow is minimized. It is possible to secure the fluidity and plasticity of urea.

Accordingly, according to the present invention, a polyurea layer having high flexibility and easy plasticization can be formed by using a straight-chain aromatic or aliphatic amine having 3 or more carbon atoms as a monomer of the polyurea as amines corresponding to the flexible part (soft segment).

The aromatic or aliphatic amine having 3 or more carbon atoms is not particularly limited as long as it can form polyurea, and for example , α, α′-diamino-m-xylene ( α, α′-Diamino- m -xylene), hexa Methylenediamine (hexamethylene diamine), isophoronediamine, polyetheramines (polyetheramines), polyoxypropylene glycol diamine (propylene diamine), N,N-dialkylmethylenediamine (N, N-dialkylmethylenediamine), 4,4-diaminodiphenyl methane (4,4-Diamino diphenyl methane), 4,4-diaminodiphenyl ether (4,4-Diaminodi phenyl ether), diethyl toluenetriamine (di -ethyl-toluene triamine: DETDA), diethylenetriamine, etc. may be used alone or in combination of two or more.

In one embodiment of the present invention, the straight-chain aromatic or aliphatic amine having 3 or more carbon atoms may have a molecular weight of 380 to 4000. If the molecular weight is less than 380, plasticization is not easily achieved, and if the molecular weight exceeds 4000, the flexibility is good, but the rigidity may be low.

The aromatic or aliphatic amine may have 3 or more linear carbon atoms, and preferably 12 or more. The upper limit of carbon number is not particularly limited as long as polyurea can be formed, but if it is too short, plasticization is difficult, and if it is too long, flexibility is good but rigidity is low, so it may be, for example, 22.

In one embodiment of the present invention, when the aromatic or aliphatic amine is a polymer, the number of carbon atoms in the repeating unit may be 2 to 6 carbon atoms.

The aromatic diisocyanate is not particularly limited as long as it can form polyurea, for example, methylenediphenyldiisocyanate (MDI), hexamethylenediisocyanate (HMDI), methylenebisparacyclohexylisocyanate (H12MDI), xylenedi Isocyanate (XDI), naphthalene diisocyanate (NDI), isophorone diisocyanate (IPDI), etc. may be used alone or in combination of two or more.

In addition, additives such as a stability enhancer of polyurea, a crosslinking accelerator and an antifoaming agent may be partially used.

The adherend is not particularly limited as long as polyurea can be applied thereto. For example, it may be metal or plastic, and in the case of metal, it may be a steel plate, a stainless steel plate, a steel pipe, a stainless steel pipe, a pipe connection part, and the like.

In one embodiment of the present invention, when the adherend is a metal, a metal oxide layer (oxidation protective film) may be formed on the surface thereof. The metal oxide layer may be a corrosion layer of a metal or an artificially formed corrosion resistance layer.

When polyurea is heat-treated at a temperature at which plasticization occurs, as shown in FIG. 2, the viscosity of polyurea is lowered and flow is possible, so adhesion with the surface of the adherend, that is, wetting, is improved, so that the adherend and polyurea As the contact area of

A film (interfacial film) will be formed at the interface between the polyurea that has been sufficiently softened and flowed and the adherend has a sufficiently low viscosity, and unlike the case of spray application, the formed film has fewer voids, so the excellent waterproofness of polyurea and the adherend Water resistance is improved.

In addition, when the adherend is a metal, the oxide protective film formed on the metal surface, that is, oxygen and metal elements such as Fe ₂ O ₃ , Cr ₂ O ₃ , ZnO, and amine of polyurea, hydrogen or oxygen of urea are chemically combined or secondary Since bonding (eg, hydrogen bonding, van der Waals bonding, etc.) occurs, adhesion is remarkably increased through the heat treatment process of this step. Accordingly, the polyurea layer according to the present invention can also be utilized as an adhesive layer.

On the other hand, the crosslinking reaction of the hardened part (hard segment) of polyurea and the hydrogen bond between hydrogen of amine and oxygen of the carbonyl group are reversible reactions. During cooling, the broken cross-links and hydrogen bonds are re-formed, so the loss of the physical properties of the polyurea is very small.

In one embodiment of the present invention, the plasticization temperature of polyurea may vary depending on specific types of monomers used for polymerization of polyurea, but when the polyurea reaches only the plasticization temperature, the viscosity is significantly lowered, so that in the present invention effect can be shown.

For example, polyurea synthesized by using a straight-chain aromatic or aliphatic amine having 3 or more carbon atoms as a monomer of the copolymer may have a plasticization temperature of 180 to 320 ° C, preferably 200 to 280 ° C, and most Preferably it may be 230 to 280 ℃, this point will be further described in Examples and Experimental Examples below.

If the temperature is less than 180° C., plasticization may not be sufficiently performed, so that the viscosity drop may not be sufficient, and if it exceeds 320° C., polyurea may be excessively thermally decomposed, which is not preferable. A detailed explanation of this is as follows.

In general, the strong physical and thermal properties of polyurea as an elastic protector are due to crosslinking that occurs in urea and urethane. A hydrogen bond occurs between oxygen contained in the carbonyl group of a molecule adjacent to hydrogen, and as the strength of the hydrogen bond is accumulated, it has stronger and tougher properties.

Due to its molecular structure, urea has twice as many hydrogen bonds as urethane. This hydrogen bond maintains and stabilizes the rigidity of polyurea, and acts as a major factor along with crosslinking. When is lowered, it has plasticity to rejoin.

On the other hand, the main temperature range of polyurea in the prior art is -40°C to +80°C, but in reality, it maintains thermal stability from about 180°C to less than 230°C depending on the comonomer, and from about 280°C to 320°C. Thermal stability is reduced.

As described above, polyurea has a microphase divided block composite form and specifically consists of a hardened part (hard segment) region dispersed in a flexible part (soft segment) matrix. Alternatively, the flow can be macroscopically represented as a flow of polyurea, and if this plasticized flow is controlled in an appropriate temperature range, damage to crosslinking of the hardened part (hard segment) can be minimized and fluidity and plasticity of polyurea can be secured. found out that

Polyurea synthesized by using aromatic or aliphatic amines having n (3) or more carbon atoms per repeating unit as monomers of the amines corresponding to the flexible part (soft segment) has high flexibility and is easy to plasticize at 180~320℃, Preferably, the flexible part may be plasticized in the range of 200 to 280 ℃, most preferably 230 to 280 ℃.

As described above, when the temperature is less than 180° C., plasticization is not sufficiently achieved, which is not preferable because the viscosity drop may not be sufficient, and when it exceeds 320° C., it is not preferable because the polyurea may be excessively thermally decomposed.

For reference, the thermogravimetric reduction was confirmed using TGA to determine the thermal decomposition of polyurea. As shown in FIG. 3, polyurea including most aliphatic amines had a weight reduction initiation temperature (5% weight loss occurred). If the temperature) exceeds about 280 ℃ and 320 ℃ or less, thermal decomposition is started in this temperature section, and if it exceeds 320 ℃, excessive pyrolysis and decomposition is terminated at 435 ~ 460 ℃.

According to the present invention, when the temperature is 230 to 280° C., the adhesion (measured by the Dolly test) is 10 times or more and the peeling strength is 8 to 16 times compared to the spray application by the conventional method (that is, when there is no heat treatment). I could tell it was over. Furthermore, when the temperature is 200 ° C or more and less than 230 ° C, the adhesive force (measured by the Dolly test) is 6 to 10 times and the peel strength is 3 times or more than the spray application by the conventional method (that is, when there is no heat treatment) It was found that .

On the other hand, when the temperature is 180 ° C or more and less than 200 ° C, the process takes longer than that of 200 to 280 ° C. could And, when the temperature is more than 280 ° C. and less than 320 ° C., the reaction rate is too fast, so there is a disadvantage that the process control is difficult, but the adhesive strength and peel strength are much larger than in the case of the conventional spray application.

Therefore, in order to increase the bonding strength with the adherend, including metal, which is a weak point of polyurea, and to make it adhesion rather than simple bonding, the temperature is 180 ~ 320 ℃, preferably 200 ~ 280 ℃, most preferably 230 ~ 280 ℃. When polyurea, which is a bonding body, is sprayed and then heated or the surface of the adherend (metal) is heated to the above temperature and then polyurea is sprayed, the viscosity of polyurea is lowered and flow is possible, so adhesion to the surface of the adherend is improved. The contact area between the metal as an adherend and the polyurea becomes large, so that the bonding strength will increase in proportion to the contact area.

A film (interfacial film) will be formed at the interface between the polyurea, which has been sufficiently softened and flowed, and the metal, which is the adherend, due to a sufficiently low viscosity. The effect of blocking the attack of moisture will increase.

According to an embodiment of the present invention, a polyurea layer may be formed on an adherend (metal tube, metal panel, etc.) heated to the plasticizing temperature. In this case, an interface film may be formed at the interface with the adherend. In addition, an interface film (external blocking film) may be formed by heating the outer surface of the polyurea layer.

Specifically, when the first polyurea layer is thinly formed on the adherend and heated to the plasticizing temperature, air bubbles included in the first polyurea layer are removed and the tissue is densified to form an interfacial film (first interfacial film). Next, a second polyurea layer is formed on the first polyurea layer. Then, an interface film (second interface film) may be formed by heating the outer surface of the second polyurea layer to the plasticizing temperature.

Since the first and second interfacial membranes remove air bubbles and densify the tissue, the waterproofness may be improved and the effect of blocking moisture attack on the adherend may be increased.

Meanwhile, as an alternative to applying the first and second polyurea layers separately as described above, the polyurea layers may be applied at once to form the polyurea layers. In this case, the outer surface of the polyurea layer and the interface with the adherend may each be formed as an interface film by heating.

When the polyurea layer is divided into the first and second polyurea layers and applied, the first polyurea layer (interfacial film) may have a thickness of about 0.3 to 0.85 mm, preferably a thickness of about 0.35 to 0.7 mm. may have, and most preferably have a thickness of about 0.5 to 0.6 mm. In addition, the second polyurea layer is thicker than the first polyurea layer, and its thickness may be determined as necessary in consideration of the use of the product, the use, the environment, and the like.

According to an embodiment of the present invention, the method may further include moving the adherend during or after the heat treatment step. When the adherend is moved, the plasticized polyurea can be more evenly applied to the surface of the adherend, thereby further improving applicability and adhesion. When the adherend is plate-shaped, the movement may be performed in a vibrating or seesaw-type movement method. The seesaw movement refers to a movement in which the left and right sides are alternately raised and lowered around any one part of the adherend. And, when the adherend is a pipe type, the movement may be performed in a rotational manner.

Specifically, if the adherend is moved, the molten polyurea spreads uniformly, making the contact area more even and wider, effectively reducing the voids or bubbles in the film occurring at the interface between the coating agent and the adherend, and forming the film evenly. . Then, the polyurea surface is heated and melted by thermal radiation heating to the plasticizing temperature of the polyurea or using a heated roller or template, and an appropriate pressure (for example, a pressure sufficient to remove the pores (bubbles) of the polyurea layer) ) to form a film on the external surface, it blocks moisture penetration more effectively to protect the adherend, and incidentally increases the adhesion by pressure. ) improves barrier properties by forming a film through re-melting/re-crosslinking, and the intermediate layer maintains sufficient pores to improve elasticity and impact resistance.

Example 1.1

Methylenediphenyl diisocyanate (MDI) and polypropylene glycol are mixed in about 75 wt% and 25 wt%, and polypropylene glycol diamine, polyetheramine, and diethyltoluenetriamine are 75 wt%, 20 wt%, and 5 wt%, respectively. % is prepared, and the isocyanate and the amine are 1:1 (volume ratio) at a temperature of 70° C. and a pressure of 17.2 Mpa (172 bar). A polyurea layer was formed on one surface of the steel plate (steel plate) by simultaneously spraying on the steel plate (steel plate). Then, the steel plate (steel plate) was heated to a temperature of 250 ℃.

Comparative Example 1.1

A steel plate coated with polyurea was prepared in the same manner as in Example 1.1 except for heat treatment at 250°C. That is, methylene diphenyl diisocyanate (MDI) and polypropylene glycol are mixed in about 75 wt% and 25 wt%, and polypropylene glycol diamine, polyetheramine, and diethyltoluenetriamine are 75 wt% 20 wt% and 5 wt%, respectively. The mixed amine was sprayed with the isocyanate and the amine at a temperature of 70° C. and a pressure of 17.2 Mpa (172 bar) in a ratio of 1:1 (volume ratio), and no heat treatment was performed.

Examples 1.2 to 1.4 and Comparative Examples 1.2 to 1.4

Examples 1.2 to 1.4 differ from Example 1.1 only in the presence or absence of an adherend or undercoat, and the remaining conditions are the same. And, Comparative Examples 1.2 to 1.4 differ from Comparative Example 1.1 only in the presence or absence of an adherend or undercoat, and the remaining conditions are the same. Specific details of Examples 1.2 to 1.4 and Comparative Examples 1.2 to 1.4 are shown in Table 1.

Examples 2.1 to 2.5

Example 2.1 is the same as Example 1.1 except that it was heat-treated at 180 ° C., Example 2.2 is the same as Example 1.1 except that heat treatment was performed at 200 ° C., and Example 2.3 was heat-treated at 230 ° C. Example 1.1 is the same except that, Example 2.4 is the same as Example 1.1, except that the heat treatment at 280 ℃. In addition, Example 2.5 is the same as Example 1.1, except that the heat treatment at 320 ℃.

Comparative Example 2.1 ~ Comparative Example 2.2

Comparative Example 2.1 is the same as Comparative Example 1.1 except for heat treatment at 160 ℃, Comparative Example 2.2 is the same as Comparative Example 1.1 except that 340 ℃ heat treatment.

Experimental example

1. Bonding strength and peeling force

For Examples 1.1 to 1.4 and Comparative Examples 1.1 to 1.4, a dolly test and a peel strength were measured, and the results are shown in Table 1 below.

(A two-component epoxy was used for the undercoat, sprayed with a thickness of 0.05mm, cured for 24 hours, and then sprayed with polyurea)

Referring to Table 1, it can be seen that the Examples have significantly higher bonding strength and peel strength than Comparative Examples.

As shown in Table 2, Examples 2.1 to 2.5 (heat treatment temperature of 180 to 320 ° C.) have superior bonding strength and peel strength compared to Comparative Example 2.1 (when heat treated at 160 ° C.), and particularly, heat treatment temperature of 230 - It can be seen that the difference is more significant when it is 280 ° C. (Examples 2.2 to 2.4).

On the other hand, Examples 2.1 to 2.5 showed no significant difference in bonding strength compared to Comparative Example 2.2 (when heat treated at 340 ° C.), but the peel strength was significantly higher. In particular, the heat treatment temperature was 230 to 280 ° C. In the case of Examples 2.2 to 2.4), it can be seen that the difference in peel strength is more remarkable.

2. Microscopic Analysis

The results of microscopic analysis of Example 1.1 and Comparative Example 1.1 are shown in FIGS. 4 to 13 .

4 to 9 are photomicrographs of Example 1.1.

Specifically, FIG. 4 is a photograph taken at 1,000 times magnification of polyurea, and it can be seen that an adhesive film is formed on the interface, the inner metal surface is projected, and no air bubbles and pores are found.

5 is a photograph taken at 1,000 times magnification of the separation of the polyurea layer from the adherend after heat-melt bonding. Compared to Comparative Example 1.1, pores were significantly reduced, and traces (grooves) of the adherend were clearly visible on the separated surface. It can be seen that the wettability is significantly increased. And, FIG. 6 is a photograph of the surface remaining on the metal side during separation of FIG. 5 , and it can be seen that the film formation is clear.

7 to 8 are photographs of the bonding surface during heat-melting bonding. It can be seen that a dense sealing film (interfacial film) is formed at the bottom of the polyurea, and the density of the sealing film (interfacial film) part is high and the pores are It can be seen that there are few

9 is a photograph (planar) showing the polyurea layer, and it can be seen that the film is stretched by adhesion and pores outside the interfacial film can be confirmed.

Meanwhile, FIGS. 10 to 13 are photomicrographs (1,000 times) of Comparative Example 1.1 (polyurea was applied by the conventional method).

Specifically, FIG. 10 is a photograph taken at 1000 times magnification of the external exposed surface (outer side) of the polyurea layer, and it can be seen that bubbles of up to 0.043 mm are observed on the surface and inside. And, FIG. 11 is a photograph showing the bonding surface between the adherend and the polyurea layer, and bubbles with a maximum observed value of 0.028 mm were found on the surface and inside.

In addition, referring to FIG. 12 , it can be seen that close adhesion is not made between the adherend and the polyurea, and a space appears clearly between the materials, and it can be seen that the polyurea does not sufficiently wet the adherend. In particular, FIG. 13 is a 100-fold magnification of the boundary portion between the adherend and polyurea, and it can be seen that air bubbles and pores are distributed throughout the cross section.

The present invention has the following effects.

First, in the method for manufacturing a composite pipe or composite panel or pipe connection part according to the present invention, the polyurea layer is heated to 180 to 320° C. and plasticized to have high adhesion and peel strength, and the contact surface with the adherend of the polyurea layer and the By forming an interfacial film on the outer surface, moisture barrier properties are improved, and elasticity and impact resistance are improved by allowing a relatively large number of pores to be included in the polyurea layer.

Second, the polyurea layer between the first and second tubes is heated and cooled sequentially from one end of the first and second tubes to the other end to bond the two tubes, but using the difference in the coefficient of thermal expansion of the first and second tubes Air bubbles contained in (adhesive layer) can be removed.

Third, to provide a composite pipe and composite panel made by the above manufacturing method.

1 is a cross-sectional view showing polyurea sprayed onto an adherend (metal surface) according to the prior art.

2 is a cross-sectional view showing polyurea heat-treated after being sprayed onto an adherend (metal surface) according to the present invention.

3 is a graph showing the TGA result of measuring the thermal decomposition of polyurea.

4 is a photograph taken at 1,000 times magnification of polyurea applied to a metal surface according to the present invention.

5 is a photograph taken at 1,000 times magnification of the polyurea layer separated from the adherend after heat-melt bonding;

6 is a photograph of the surface remaining on the metal side when the separation of FIG. 5 is performed.

7 to 8 are photographs of the bonding surface during heat-melt bonding.

9 is a photograph (planar view) showing a polyurea layer that is heat-melted bonded.

10 is a 1000-fold magnification of the externally exposed surface (outer surface) of the polyurea layer applied by the conventional method.

11 is a photograph showing a bonding surface between an adherend and a polyurea layer (applied by a conventional method).

12 is a photograph taken of the boundary portion between the adherend and the polyurea layer (applied by the conventional method).

13 is a 100-fold magnification of the boundary portion between the adherend and the polyurea layer.

14 is a cross-sectional view showing a composite pipe manufactured according to the present invention.

15 is a flowchart showing a method for manufacturing a composite pipe according to the present invention.

16A to 16F are views sequentially showing a heating method according to the present invention.

17A is a cross-sectional view showing a composite panel manufactured according to the present invention;

17B is a cross-sectional view showing another composite panel made in accordance with the present invention;

[Composite pipe and its manufacturing method]

The present invention can be applied to a composite pipe of various materials, and is not applied only to a composite pipe of a specific material. That is, the present invention can be applied to a composite pipe made by inserting a second pipe inside the first pipe. However, below, for convenience of description, a case in which the stainless steel pipe 30 is inserted into the steel pipe 10 will be described as an example.

14 is a cross-sectional view showing a composite pipe manufactured according to the present invention, and FIG. 15 is a flowchart showing a process for manufacturing the composite pipe.

The composite pipe 100 includes a steel pipe 10, a stainless steel pipe 30 inserted into the steel pipe 10, and at least one of the inner surface of the steel pipe 10 and the outer surface of the stainless steel pipe 30. It includes a first polyurea layer 20 formed, a first polyurea layer 22 formed on the outer surface of the steel pipe 10 , and a second polyurea layer 40 formed on the first polyurea layer 22 . do. The composite pipe 100 is mainly used as a water supply pipe, but is not necessarily limited thereto.

The first polyurea layer 20 may be formed on at least one of the inner surface of the steel pipe 10 and the outer surface of the stainless steel pipe 30 , but below, for convenience of description, the first polyurea layer 20 ) is assumed to be formed on the inner surface of the steel pipe (10). When the first polyurea layer 20 is formed on the outer surface of the stainless steel tube 30, its configuration will be easily understood with reference to the following description, and thus a description thereof will be omitted.

The method for manufacturing the composite pipe includes the steps of forming a first polyurea layer 20 on the inner surface of the steel pipe 10 and forming the first polyurea layer 22 on the outer surface of the steel pipe 10 (S10); 1 Step of forming the second polyurea layer 40 on the polyurea layer 22 (S20), inserting the stainless steel pipe 30 into the steel pipe 10 (S30), the steel pipe 10 and The step of expanding the stainless steel pipe 30 (S40), heating the steel pipe 10 and the stainless steel pipe 30 to remove air bubbles in the first polyurea layer 20 and 22 to remove the air bubbles from the pipes 10 and 30 ) and increasing the adhesion between the first polyurea layer 22 and the steel pipe 10 ( S50 ), and heating the outer surface (outer surface) of the second polyurea layer 40 . to form the second interfacial layer 45 by removing air bubbles and making the tissue dense (S60). Meanwhile, step S20 may be performed at any time after step S10 and before step S60. 15 , the dotted line indicates that step S20 may be performed between steps S10 and S30, between steps S30 and S40, between steps S40 and S50, and between steps S50 and S60. However, below, for convenience of description, a case in which step S20 is performed between steps S10 and S30 will be described.

Each of the above steps will be described below.

First, the first polyurea layer 20 is formed on the inner surface of the steel pipe 10 and the first polyurea layer 22 is formed on the outer surface of the steel pipe 10 ( S10 ). As described above, the first polyurea layer 20 may be formed on at least one of the inner surface of the steel pipe 10 and the outer surface of the stainless steel pipe 30 .

The first and second polyurea layers 20 and 22 may have a thickness of about 0.3 to 0.85 mm, preferably about 0.35 to 0.7 mm, and most preferably about 0.5 to 0.6 mm. may have a thickness of

If the thickness is less than the lower limit (0.3mm), adhesive strength and moisture barrier are not sufficient, and if it is larger than the upper limit (0.85mm), it is not preferable because it becomes too thick.

The polyurea layers 20 and 22 may be formed by spraying an aromatic diisocyanate and a linear aromatic or aliphatic amine having 3 or more carbon atoms on the inner and outer surfaces of the steel pipe 10 in a 1:1 (volume ratio) ratio. The specific kind of the aromatic diisocyanate and the specific kind of the amine have been described above.

Following S10, a second polyurea layer 40 is formed on the first polyurea layer 22 (S20). The constituent components and application method of the second polyurea layer 40 are the same as the constituent components and application method of the polyurea layers 20 and 22 . However, the thickness of the second polyurea layer 40 may be determined according to the use and necessity of the product.

Next, the stainless steel pipe 30 is inserted into the steel pipe 10 (S30). The outer diameter of the stainless steel pipe 30 is slightly smaller than the inner diameter of the steel pipe 10 , but has a diameter difference to the extent that it can be closely coupled to the inner surface of the steel pipe 10 by a subsequent pipe expansion and heating process.

Next, the steel pipe 10 and the stainless steel pipe 30 are expanded to couple the steel pipe 10 and the stainless steel pipe 30 (S40).

The expansion is a method for bonding heterogeneous pipes to each other, and may be made by hydroforming or by an expansion mold. Since the hydroforming and expansion mold are known in the art, a description thereof will be omitted.

Meanwhile, although it has been described above that the tube is expanded after the second polyurea layer 40 is formed, the second polyurea layer 40 may be formed after the tube is expanded.

Next, the steel pipe 10 and the stainless steel pipe 30 are heated (S50). The heating is performed at 180°C to 320°C, preferably 200°C to 280°C, and most preferably 230°C to 280°C, which is the temperature at which the plasticization phenomenon occurs.

The polyurea formed by spraying the aromatic diisocyanate and the amine consists of a hardening part and a flexible part, the flexible part has 3 or more straight-chain carbon atoms, and the flexible part is plasticized according to the plasticization so that the polyurea is partially plasticized. can

The plasticization or flow of the flexible part (soft segment) can macroscopically appear as the flow of polyurea, and when this plasticized flow is adjusted in an appropriate temperature range, damage to the crosslinking of the hardened part (hard segment) is minimized and polyurea flow is minimized. It is possible to secure the fluidity and plasticity of urea.

As described in Tables 1 and 2 above, the first polyurea layers 20 and 22 heat-treated at the above temperature have very high adhesion and peel strength compared to the polyurea layers applied by the conventional method. It can be used as an adhesive.

That is, a film (interfacial film) will be formed by a sufficiently low viscosity on the interface between the polyurea, which has been sufficiently softened and flowed, and the steel pipe 10, and unlike the case of spray application, the formed film has relatively few voids, so Water resistance and adhesion are improved.

And, when an oxidation protective film or corrosion-resistant layer is formed on the surface of the steel pipe 10, oxygen and metal elements such as Fe ₂ O ₃ , Cr ₂ O ₃ , ZnO, amine of polyurea, hydrogen or oxygen of urea are chemically combined or secondary bonding occurs, so that the adhesiveness is remarkably increased through the heat treatment process. Accordingly, the steel pipe 10 and the stainless steel pipe 30 may be firmly coupled to the first polyurea layer 20 by the expansion of the pipe.

Then, by the heating, air bubbles in the first polyurea layer 22 are removed, and the structure becomes dense to form a first interfacial film. 7 shows an interfacial film (first interfacial film, 22) formed between the metal layer and the polyurea layer. The first polyurea layer 22 has very high adhesive strength and peel strength compared to the conventional polyurea layer, and this point has been described in Tables 1 and 2 and the like.

On the other hand, as shown in Figs. 16a to 16f, it is preferable that the heating is sequentially performed from one end of the steel pipe 10 toward the other end, and cooling is performed while following the heating at a predetermined interval. This is because the thermal expansion coefficient of the stainless steel pipe 30 is greater than that of the steel pipe 10, so when the steel pipe 10 and the stainless steel pipe 30 are heated, the bubbles of the first polyurea layer 20 are pushed and moved. . That is, when sequentially heated from one end of the steel pipe 10 toward the other end, the bubbles of the first polyurea layer 20 move from one end to the other end and then are discharged to the outside. At this time, when cooling while maintaining a predetermined distance from the heated portion, it is possible to prevent the backflow of air bubbles.

After the heating, cooling is performed, and cooling may be achieved by forcibly supplying cold air. Preferably, the cooling can be performed by following a heating device (not shown in the drawing) or a heated part at a predetermined interval, which prevents the bubble 91 from moving (reverse flow) in the opposite direction (one end of the tube). This is to prevent it from moving to the other end of the tube.

Upon cooling, the steel pipe 10 has a greater force to return to its original shape than the stainless steel pipe 30 , so that the steel pipe 10 and the stainless steel pipe 30 may be closely coupled. That is, the steel pipe 10 and the stainless steel pipe 30 may be closely coupled by the expansion pipe and the adhesive layer.

On the other hand, in order to manufacture a single tube, as shown in FIGS. 16E to 16F , the tube expansion mold 300 may be inserted into the other end of the tube. In a state in which the tube is heated, the tube is expanded by expanding the tube expansion part 310 in the radial direction of the tube after the tube expansion mold 300 is inserted into the tube. After the tube expansion is completed, the end of the tube may be finished with resin and metal (96). This closing can be done before or after the expansion.

After the step S50, the outer surface of the second polyurea layer 40 is heated to remove air bubbles and the tissue is made dense to form the second interfacial film 45 (S60).

The heating may be performed at the same temperature as the heating in step S50. In addition, the heating may be performed by conduction, radiation, ultrasonic heating, or the like, and a predetermined pressure may be applied to the second polyurea layer 40 together with heating.

Through the above process, on the outer surface of the steel pipe 10, a large amount of air bubbles are removed and the first interface film 22 (a layer that blocks the inflow of moisture) with increased adhesion, a buffer layer 41 containing a relatively large amount of air bubbles, and A second interface film 45 (external shielding layer) from which many bubbles are removed is formed. A first polyurea coating layer 20 (adhesive layer) from which air bubbles are removed is formed between the steel pipe 10 and the stainless steel pipe 30 .

On the other hand, it may further include the step of moving the composite pipe during the heating (heat treatment) step or after the heating (heat treatment) step. When the composite tube is moved, the plasticized polyurea can be applied more evenly to the surface of the tube, thereby further improving the applicability and adhesion.

Specifically, when the composite pipe is moved, the molten polyurea is uniformly spread to make the contact area more even and wider, effectively reducing the voids or bubbles in the film occurring at the interface between the coating agent and the adherend, and forming the film evenly. In addition, if the polyurea surface is heated and melted by thermal radiation heating to the plasticizing temperature of the polyurea or using a heated roller or template, and a film is formed on the external surface by applying an appropriate pressure, moisture penetration is blocked more effectively to protect the tube In addition, the effect of increasing the adhesion by pressure can be obtained incidentally, and the barrier properties of both sides of polyurea, i.e., the tube adhesion surface and the outer surface, are improved by film formation through re-melting/re-crosslinking, and the intermediate layer maintains sufficient voids. The effect of improving elasticity and impact resistance can be obtained.

The movement may be made in various ways, but in the case of a composite pipe, it may be performed by applying rotation or vibration.

[Composite panel and its manufacturing method]

17A is a cross-sectional view showing a composite panel manufactured according to the present invention.

As shown in the drawing, the composite panel 200 includes a metal panel 50 and first and second polyurea layers 72 and 60 formed on the upper surface of the metal panel 50 . The composite panel 200 may be used for various purposes, for example, a water tank.

In addition, the method for manufacturing the composite panel includes forming a first polyurea layer 72 on a metal panel 50 , and heating at least one of the metal panel 50 and the first polyurea layer 72 . to form a first interfacial film, forming a second polyurea layer 60 on the first polyurea layer 72 , and heating an outer surface (outer surface) of the second polyurea layer 60 to form the second interfacial layer 65 by removing air bubbles and making the tissue dense.

Each of the above steps will be described below.

First, a first polyurea layer 72 is formed on the metal panel 50 . The components (materials) used for the first polyurea layer 72, the formation method, and the thickness thereof are the same as the components, the formation method, and the thickness of the first and second polyurea layers 20 and 22 described above. As a metal panel, a steel plate, a stainless steel panel, etc. may be used.

Next, at least one of the metal panel 50 and the first polyurea layer 72 is heated to form a first interface layer. The heating may be performed by heating the metal panel 50 or may be performed by directly heating the first polyurea layer 72 . On the other hand, since the polyurea is applied in a state in which the metal panel 50 is previously heated to a plasticizing temperature, plasticization may be performed immediately after the polyurea is applied.

The heating temperature is the same as the heating temperature of the first polyurea layers 20 and 22 described above. In the first interface film formed by the heating, air bubbles (or voids) are removed, the tissue is densified, moisture penetration is prevented, and the adhesive strength and peel strength with the metal panel 50 are improved. The principle of the polyurea coating layers 20 and 22 is the same.

Next, a second polyurea layer 60 is formed on the first polyurea layer 72 . The components (materials) used for the second polyurea layer 60 and the formation method are the same as those of the second polyurea layer 40 .

As described above, the application of the second polyurea layer 60 may be performed after the first interfacial film is formed by heating the first polyurea layer 72 , or may be performed before the heating of the first polyurea layer 72 .

On the other hand, the first and second polyurea layers 72 and 60 may be formed at once instead of being formed separately. In this case, the metal panel 50 is heated to form a first interface film and the outer surface of the polyurea layer is formed. The second interface film may be formed by heating.

After the second polyurea layer 60 is formed, the outer surface (outer surface) of the second polyurea layer 60 is heated to form the second interface layer 65 . The heating may be performed in the same way as the heating in step S60.

The heating temperature is the same as the heating temperature for forming the first interface film 72 . The heating may be performed by conduction, radiation, ultrasonic heating, or the like, and a predetermined pressure may be applied to the second polyurea layer 60 together with heating.

Through the above process, air bubbles are removed from the outer surface of the metal panel 50 and the first interfacial film 72 (a layer that blocks the inflow of moisture), the buffer layer 61 containing air bubbles, and air bubbles having increased adhesion are removed. A second interfacial film 65 (external shielding layer) is formed.

The method may further include moving the composite panel 200 during or after the heating (heat treatment) step. When the composite panel 200 is moved, the plasticized polyurea can be more evenly applied to the panel surface, thereby further improving applicability and adhesion.

The movement may be performed in various ways, and preferably, the panel 200 may be moved or vibrated on a seesaw. This seesaw movement is a movement that alternately raises and lowers the left and right sides of the panel around the center.

Meanwhile, as shown in FIG. 17B , the composite panel 200 may further include a metal panel 55 bonded to the second interface layer 65 . The metal panel 55 is coupled by the adhesive force of the second interface layer 65 . The metal panel 55 may be the same metal as the metal panel 50 or a different metal.

[Pipe connection part]

The present invention can also be applied to pipe connecting parts such as fittings. For reference, an example of an existing pipe connection part is disclosed in Republic of Korea Public Utility Model No. 20-1991-0009356 and the like.

A pipe connecting part according to the present invention, a joint pipe (pipe); It may include; a polyurea layer formed on the outer surface of the joint and applied by the method described above. The joint pipe may be a steel pipe, a stainless steel pipe, or the like. And, the polyurea layer is plasticized heat treatment by heating to a plasticizing temperature.

Claims (19)

1. (a1) forming a first polyurea layer 20 on at least one of the inner surface of the first tube and the outer surface of the second tube;

   (a2) forming a first polyurea layer 22 on the outer surface of the first tube;

   (a3) forming a second polyurea layer 40 on the first polyurea layer 22;

   (a4) inserting the second tube into the interior of the first tube;

   (a5) after step (a4), expanding the first and second tubes;

   (a6) By heating the first and second tubes to remove air bubbles in the first polyurea layers 20 and 22, the adhesive force of the first and second tubes is improved and a first interface film is formed on the outer surface with the first tube to do; and,

   (a7) forming the second interfacial film 45 by heating the outer surface of the second polyurea layer 40 to remove air bubbles and densify the tissue;

   In the heating of steps (a6) and (a7), the polyurea is attached by heating to a temperature at which plasticization occurs,

   Step (a3) is performed between steps (a2) and (a4), between steps (a4) and (a5), between steps (a5) and (a6), and between steps (a6) and (a7). Composite pipe manufacturing method, characterized in that made at any one time.
2. According to claim 1,

   The second tube has a higher coefficient of thermal expansion than the first tube, and the heating in step (a6) is sequentially performed from one end to the other end of the composite tube, and the bubbles of the first polyurea layer 20 by the sequential heating A method for manufacturing a composite pipe, characterized in that it is discharged to the outside by moving from one end of the composite pipe to the other.
3. 3. The method of claim 2,

   The first and second polyurea layers 20, 22 and 40 are formed by spraying an aromatic diisocyanate and a linear aromatic or aliphatic amine having 3 or more carbon atoms.
4. 4. The method of claim 3,

   In the first and second interfacial films, air bubbles are removed through re-melting or re-crosslinking, and moisture barrier properties are increased. Composite pipe manufacturing method, characterized in that this improved.
5. 5. The method of claim 4,

   The method for manufacturing a composite pipe, characterized in that the temperature at which the plasticization phenomenon appears is 180 ℃ ~ 320 ℃.
6. first tube;

   a second tube inserted into the first tube;

   a first polyurea layer 20 formed between the first and second tubes to couple the first and second tubes;

   a first polyurea layer 22 formed on the outer surface of the first tube; and,

   a second polyurea layer 40 formed on the first polyurea layer 22;

   The first polyurea layer 22 forms a first interfacial film,

   The second polyurea layer 40 is

   a second interfacial film 45 formed on the outer surface of the second polyurea layer 40; and,

   a buffer layer 41 formed between the first interfacial film and the second interfacial film 45;

   In the first polyurea layer 20 and the first and second interfacial films, air bubbles are removed by re-melting or re-crosslinking of the polyurea and a film is formed to increase moisture barrier properties, and the buffer layer 41 is formed by the first and second interfacial films. Composite pipe, characterized in that elasticity and impact resistance are improved by including more air bubbles.
7. 7. The method of claim 6,

   The first and second tubes are a composite tube, characterized in that the second tube is inserted into the first tube and then the tube is expanded and the first polyurea layer (20) is coupled.
8. 8. The method of claim 7,

   The first and second tubes are metal tubes,

   Oxygen and metal elements of the oxidation protective film formed on the surface of the metal tube, amine of the first polyurea layer 20 and the first interfacial film, and hydrogen or oxygen of urea are chemically bonded or secondary bonded, thereby improving adhesion complex pipe.
9. 9. The method according to any one of claims 6 to 8,

   The first and second polyurea layers 20, 22 and 40 are composite pipe, characterized in that formed by spraying an aromatic diisocyanate and a straight-chain aromatic or aliphatic amine having 3 or more carbon atoms.
10. A composite pipe manufactured by the manufacturing method of any one of claims 1 to 5.
11. (c1) forming a first polyurea layer 72 on the metal panel 50;

    (c2) heating at least one of the metal panel 50 and the first polyurea layer 72 to remove air bubbles in the first polyurea layer 72 to form a first interface film;

    (c3) forming a second polyurea layer 60 on the first polyurea layer 72; and,

    (c4) heating the outer surface of the second polyurea layer 60 to remove air bubbles and dense the tissue to form the second interfacial film 65;

    Step (c3) is made between steps (c1) and (c2) or is made between steps (c2) and (c4),

    The heating in the steps (c2) and (c4) is a method for manufacturing a composite panel, characterized in that heating to a temperature at which the plasticization phenomenon of polyurea occurs.
12. 12. The method of claim 11,

    The first and second polyurea layers 72 and 60 are formed by spraying an aromatic diisocyanate and a linear aromatic or aliphatic amine having 3 or more carbon atoms.
13. 13. The method of claim 12,

    In the first and second interfacial films, air bubbles are removed through re-melting or re-crosslinking, and moisture barrier properties are increased. A method for manufacturing a composite panel, characterized in that the impact property is improved.
14. 14. The method of claim 13,

    The method for manufacturing a composite panel, characterized in that the temperature at which the plasticizing phenomenon appears is 180 to 320 ℃.
15. metal panel 50; and,

    a first polyurea layer 72 formed on the metal panel 50; and,

    a second polyurea layer 60 formed on the first polyurea layer 72;

    The second polyurea layer 60 is

    a second interfacial film 65 formed on the outer surface of the second polyurea layer 60 ; and,

    a buffer layer 61 formed between the first polyurea layer 72 and the second interfacial film 65;

    The first polyurea layer 72 forms a first interfacial film,

    In the first and second interfacial films, air bubbles are removed by re-melting or re-crosslinking of polyurea and a film is formed to increase moisture barrier properties, and the buffer layer 61 contains more air bubbles than the first and second interfacial films to improve elasticity and resistance Composite panel, characterized in that the impact properties are improved.
16. 16. The method of claim 15,

    The first and second polyurea layers 72 and 60 are formed by spraying an aromatic diisocyanate and a straight-chain aromatic or aliphatic amine having 3 or more carbon atoms,

    The re-melting or re-crosslinking is a composite panel, characterized in that made at 180 ℃ ~ 320 ℃.
17. 17. The method of claim 16,

    A composite panel, characterized in that the oxygen and metal elements of the oxidation protective film formed on the metal panel (50) are chemically bonded or secondary to hydrogen or oxygen of the amine and urea of the first interfacial film, and thus adhesion is improved.
18. 18. The method of claim 17,

    Further comprising a metal panel 55 coupled to the upper surface of the second interface film 65,

    A composite panel, characterized in that the metal panel (55) is joined by a second interface film (65).
19. A composite panel manufactured by the manufacturing method of any one of claims 11 to 14.

Images