JPS598431B2 - Coating film construction method for railway vehicle roofs - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for applying a coating film to the roof of a railway vehicle.

In recent years, corrugation plates have come into use as railway vehicles have become lighter and require extremely thin metal plates with high strength.

Conventionally, the roof structure of railway vehicles has often been made by processing a flat steel plate as a substrate into a roof shape, and then attaching a polyvinyl chloride resin roofing cloth to the roof.Especially in the case of DC trains, the steel plate is used as a vinyl chloride resin roofing cloth. Corrosion often occurs due to water seepage through welded fabric.

Reducing the weight of vehicles in recent years is not just about reducing electricity and power costs, but also reducing track maintenance, reducing the capacity and number of power units, reducing the amount of wear on brake shoes, and reducing vehicle costs and acceptance inspections. Aluminum cars are popular today due to the large profits in terms of
Stainless steel cars are appearing. The aim is to prevent corrosion of the structure, eliminate paint, and reduce weight. Stainless steel has excellent corrosion resistance, so a thin plate of 1 mm or less can be used for the plate material, but in this case, the buckling load will be low, so corrugated steel plates (corrugation plates) are used to provide rigidity.
and use it.

This has a thermal conductivity of about i and a thermal expansion at high temperatures of about 40% greater than that of an ordinary steel plate, making it difficult to eliminate butt welding strain. For this reason, the joints of thin plates are often lap joints (spot welding)゜Stainless steel is austenitic J
Since high tensile strength materials made by cold rolling and tempering ISSUS301, SUS201, and SUS304 are used, the structural members and outer panels are extremely thin compared to steel vehicles. Normally, the corrugation plate on the outer panel of a vehicle is 0.8~
1.0mm) Roof corrugation board is 0.4~0.
1.2 to 2.0 mm plates are used for the 5 mm and side pillars.

Aluminum alloys have the advantage of being lighter than ordinary steel, being about -20% lighter, but they also have a lower modulus of elasticity, and have the disadvantage of being inferior in rigidity if they have the same structure.

The current structure of spot welding of corrugation plates leaves gaps in the welded areas, and over many years, water can get in between the grooves of the corrugated steel plates and the PVC resin roof fabric, leading to corrosion. As the shape of roof substrates becomes more complex due to water leakage and water ingress due to breakage of welds in the roof fabric, there is a long-awaited need for the development of materials and construction methods suitable for this. Under these circumstances, in recent years, vinyl chloride resin roofing cloth has been replaced as a vehicle roofing material, and as a construction method that is superior in terms of multi-functionality and durability, it is used directly on the flat steel roof substrate or after applying a primer on the existing roofing material. Some coating methods have come into use using two-component, non-sag type polyurethane resin roofing materials that have a high initial viscosity to prevent sagging.

Non-sag type two-component polyurethane coated roofing materials have uneven film thickness due to the mixing of the two-component mixture due to the mixing of the two-component mixture and the mixture in areas with poor stirring, and the reliability of the function of vehicle roofing materials such as a decrease in withstand voltage. There were limits to what could be given.

In other words, even if a standard coating thickness of 21 mm is set, there are distortions in the roof substrate due to train construction, and even if you try to apply a uniform coating thickness along the roof shape by troweling, there will be uneven convex parts, rising surfaces, etc. Corners tend to be thinner. In order to increase the reliability of the coating's function, it is necessary to use more paint by increasing the number of layers or increasing the thickness compared to standard specifications. Therefore, the total amount of roofing material used per vehicle is 2001<f! It becomes more than that. Even if the coating method provides the unique rust prevention characteristics and durability, the traditional PVC-based resin roofing fabric
It is heavier in weight compared to 100 to 1501<9 per vehicle, and goes against the aforementioned trend of lighter vehicles, which is a need of the times. Basically, a thin and high-performance coating system for railway vehicle roofs is expected, but as the expected corrosion resistance of the vehicle body increases, the thickness of the coating inevitably increases. Therefore, if the thickness is increased, sagging will occur, and sagging is a phenomenon that occurs when a coating material is applied thickly to a sloped complex structural surface such as the shape of a vehicle roof. This results in a type of defect that presents a pattern that is difficult to see. Generally, the sagging phenomenon tends to occur in the following cases.

(1) Thick coating (2) Slow curing of the coating (3) Excessive dilution with highly volatile thinner (4) Improper mixing The viscosity of the film material and the thickness of the coating film are the dominant factors, and leveling refers to the disappearance of irregularities during the coating process to make the film smooth, and the film thickness is particularly the dominant factor.

The coating method requires flow characteristics that are contradictory to sagging prevention and leveling properties, as described above, but when coating the actual shape of a vehicle roof substrate, it can be applied with good workability and the coating after application is easy. Ideally, the film is maintained in a state convenient for leveling for a short period of time, after which the apparent viscosity increases to prevent sagging, and four conditions are met: workability, leveling, sagging prevention, and prevention of froth contamination. A coating film that satisfies all of these is what is long awaited.

In recent years, a roof coating method has been implemented in which active hydrogen-containing materials such as polyols and amines are reacted with isocyanate components at room temperature to form urethane. Since it is extremely difficult to form a constant film thickness along the alternately repeated sloped complex roof shape using general non-sag type or self-leveling type coating materials, the present inventor developed a method for reducing spray particles in the spray method. As a result of research focusing on the characteristics of polyurethane, which allows for flexible material design by selecting the material composition and crosslinking conditions for atomization and prevention of sagging, we have found that we have developed a material that can be used as a vehicle roofing material without sacrificing its function as a vehicle roofing material. In order to prevent contamination, the two liquids are mixed in a low viscosity range, and the viscosity is rapidly changed by using a regulating chemical reaction, and the chemical reactivity is characterized by hardening through a thixotropic viscosity range immediately after spraying. A two-liquid room-temperature-curing polyurethane coating roofing material is applied to panels with complex roof shapes with a constant film thickness over the entire surface in an economical manner and with high internal fluid pressure and high reliability of construction film quality. We have discovered a method to efficiently atomize and paint polyurethane-coated roofing materials using a jet of compressed air.

That is, the temperature of the two components (main agent and curing agent) of the roof coating material is raised separately to lower the viscosity (preferably to 400 to 60 Cps, 500 to 3000 Cps, preferably 1000 to 15 Cps).
00cps), a combination of a spray method that mixes in a low viscosity range without adding thinner and uses internal liquid pressure and compressed air pressure to make the sprayed particles finer, and a special formulation of a urethane composition that makes this possible. I have successfully completed this invention.

In addition, due to the material composition with emphasis on economic considerations, functional changes in polyurethane-coated roofing materials using prepolymer isocyanates whose main raw materials are aromatic isocyanates such as tolylene diisocyanate and methylene diphenyl diisocyanate are limited to chemical changes only in the surface layer of the coating film ( yellowing) is larger than the change in the practical physical properties of the entire coating film.

On the other hand, it is known that chemical changes (yellowing) on the surface of urethane coatings using aliphatic isocyanates are extremely small, but the cost is relatively high.

Therefore, in the present invention, the chemical change in only the surface layer of the urethane coating film under exposure to ultraviolet rays, oxygen, ozone, etc. is to the extent that there is no problem in terms of the practical functionality of the coating film, so the above-mentioned disadvantages can be overcome. To solve this problem, to impart weather resistance, a film of a constant thickness is formed using aromatic isocyanate along the shape of the roof substrate using the spray method, and then a non-yellowing bullet made of aliphatic isocyanate adduct as the main raw material is applied on top of it. By laminating thin coatings, we have found a coating that is optimal for both durability and vehicle roof coating functionality. In the method of the present invention, it is assumed that degreasing, cleaning, or coating of a primary primer such as a known etching primer, epoxy resin primer, or urethane resin primer is performed as a pretreatment to prepare the base substrate. This greatly influences the durability of the coating film, and the advantages of the method of the present invention are optimally exhibited on substrates prepared in these conditions.

Since construction progresses mainly in the vehicle manufacturing process, it is not always possible to set up an ideal process for the roof painting process, but it is possible to extend the painting process as an undercoat layer for corrosion-resistant paint on the roof structure.
In order to reduce the need for repair painting and save resources, when there is a time gap in the process, we use a two-component epoxy resin primer as a secondary primer to ensure stable adhesion with the primary anti-rust primer. 2-component polyurethane resin primer,
Alternatively, a one-component polyurethane primer is essential.

The present invention focuses on the chemical reactivity necessary to form a constant film thickness of polyurethane coated roofing material on complex-shaped boards such as corrugation boards after applying the primary or secondary primer in the painting process.

Among these, the reactivity between polyamine and isocyanate is the most important. Next, the reactivity of various active hydrogen atoms and isocyanates is shown in the following order (numbers are reaction rate ratios): aliphatic amine>aromatic amine>primary 0H> (100~
10) (5~2) (1) Secondary 0H〉Water (H2O
) Otsu 4 - ゛ 4 The average chemical structure of a polyurethane elastic body is a linear elastic body composed of hard segments and soft segments.
There are two types of segments: those based on urethane group chains and those based on urea group chains.

The soft segment consists of a partially fragmented propylene chain in a polyol, and the hard segment corresponds to a chain of urea groups, that is, a polyurea polymer.
Amine-based chain extenders for forming polyurethane resins have favorable physical properties in that they can introduce urea bonds, which have a higher hydrogen bonding capacity than urethane bonds, into hard segments, but the reaction rate is too high, making it difficult to form polyurethane coatings. Because of this difficulty, aromatic amines are generally used, and among these aromatic polyamines, which have a structure that suppresses reaction events, such as 3,3'dichloro4,4'diaminodiphenylmethane, are mainly used. .

In the process of forming a continuous laminated coating film by spraying to form a polyurethane coating film, intense chemical reactivity alone tends to hinder the development of homogeneous physical properties such as adhesion and strength, so in the present invention, thixotropic The chemical reactivity is such that it has a viscosity range that is effective in preventing sagging and a suitable time for curing.

In other words, the biggest problem with thick coating is to prevent sagging, so to create a thixotropic state, powder, thixotropic agent, etc. are mixed in advance to increase the initial viscosity of one of the two liquids. Non-sag type coating materials are known that increase the initial viscosity after mixing two liquids to a thixotropic state. The present inventors have decided to use 4,4' diamino difluoride, which is highly reactive among aromatic amines, because it has the disadvantages of decreasing functionality, necessarily requiring an uneconomical film thickness, and increasing weight. enylmethane DAM to 3,3'dichloro4,
By using it in combination with 4'diaminodiphenylmethane MOCA, we have found a chemically reactive formulation that gels before sagging occurs immediately after spraying and cures after this state. The present invention uses a two-component mixing method for spraying two-component polyurethane coated roofing materials, and a structural mixer (laminar flow subdivision method) in which short metal pieces twisted clockwise and counterclockwise are alternately lined up and press-fitted into a pipe. A static mixer (1) is installed at the junction of component A and component B, and by passing the two liquids in a low viscosity range, it is possible to easily and advantageously prevent foaming and to mix the two liquids completely. The viscosity of the two-component mixture is low and fluid until it reaches the roof substrate from the spray nozzle, and immediately after reaching the substrate and leveling and adhering, it undergoes thixotropy with a rapid viscosity change before sagging occurs. By forming a continuous layered coating in tropical conditions, sagging can be prevented, and the coating is completely cured while developing homogeneous coating strength.

By combining a formulation that does not cause gelling problems and a spraying machine, the process can reduce the number of personnel, time, and construction period required for conventional non-sag type trowel coating (by approximately - to -). The 23 film also showed good uniformity, with a thickness of 1 to 1.571 compared to the conventional film thickness of 3 to 4.
It is thin at 7 ft and has better voltage resistance and coating function than conventional ones, making it economically advantageous.

This method is mainly used for spraying corrugated plates, but it can also be used for flat plates.Even for corrugated plates, the grooves are filled with lightweight filler and fixed with adhesive to give a smooth finished surface (same level as flat steel plates). ), there is also a constant coating film along the shape of the corrugated steel sheet, or the top surface of the corrugated steel sheet (
flat areas) and rising surfaces (side surfaces of grooves) are 1 to 1.
51&7! Since spot welding is performed at the bottom of the groove with a film thickness of L, it can also be used in cases where the welded part is buried with a film thickness of 2 to 5 mm. In addition, the second aspect of the present invention
Roofing materials coated with liquid polyurethane are not only for spray use,
The chemical reactivity can be adjusted freely to make it suitable for small-area repair coatings on vehicle roofs, waterproof coatings for other general buildings, and convenient troweling work, so the range of use is extremely wide. You can expect it.

The basic formulation is tolylene diisocyanate TDI - methylene diphenyl diisocyanate MD] composite prepolymer isocyanate as component A, polyol, polyamine, and modifiers, powders, plasticizers, flame retardants, pigments, and catalysts as necessary. A suspension obtained by mixing the above components is mixed as component B at a predetermined mixing ratio in a low viscosity range, and then the chemical reactivity is such that the urethane is formed with a sudden change in viscosity.

The spray formulation that has characteristics in terms of construction method is the combination formulation of MOCA (mentioned above) and T by the use of polyamine in component B.
After mixing the two components by reaction with DI-MD combined prepolymer isocyanate, rapid viscosity change rate can be optimally controlled.

The chemical reactivity is adjusted by using DAM-rich component B for the spray formulation, and MOCA-rich for the troweling formulation, which is convenient for partial repairs. As for the prepolymer isocyanate composition, the reaction between TDI and aromatic amine is too rapid, and MDI
Since the reaction between aromatic amines and aromatic amines is slow at low temperatures, a composite prepolymer isocyanate (one TDI prepolymer and one MDI prepolymer are mixed together in a one-step prepolymerization reaction consisting of TDI-MDI and polyol as isocyanate components) However, it is disadvantageous in terms of stability and cost, so it is manufactured in one step).

The greatest advantage of using TDI{DI-based composite prepolymer isocyanate is that it is useful for providing an appropriate time interval from thixotropic state to curing after viscosity change, and is useful for forming continuous fine particle layers by sobriety. This step is an important factor in achieving uniform physical properties during urethanization.

Therefore, the present invention is characterized by controlled chemical reactivity by the combination of two types of aromatic amines and the combination of two types of isocyanate components, respectively A component and B component.

Furthermore, by mixing hydroxy fatty acid esters and castor oil fatty acid esters into component B, we can improve the fluidity of the liquid in the static mixer, prevent gelation in the static mixer, and improve the flow from the nozzle. It has also been found that, in combination with lowering the viscosity of the liquid, it is also extremely effective in controlling strength development over a relatively long period of time from the thixotropic state to hardening.

A method of coating roofs for vehicles that economically forms a uniform film thickness on complex-shaped substrates such as corrugation plates by combining a formulation that causes rapid changes in viscosity through a controllable chemical reaction and a spray machine has been developed by non-inventors. The cured coating film obtained by the method of the present invention has physical properties equivalent to the JISA6O2L roof waterproofing material standard, passed the railway vehicle material combustion standard, and in the withstand voltage test,
The withstand voltage maintained for 10 minutes at 20k/10 obtained with a conventional non-sag type trowel-coated two-component polyurethane roofing material with a thickness of 3 to 4 m71L is 20k/10 with the coating film of the present invention at a coating thickness of 1 to 1.5 m1. Since it has a withstand voltage of more than 1 minute, it can be made into a thin film, which is compatible with the concept of reducing the weight of vehicles.The construction method that integrates a layered non-yellowing elastic paint on the surface improves durability, waterproofness, corrosion resistance, and It is ideal for vehicle roof coatings due to its electrical insulation properties.

Next, an example of the present invention will be shown, and the steps are as follows. FIG. 1 is an explanatory cross-sectional view of a vehicle to which the polyurethane roofing material of the present invention is coated by the spray method, and X indicates a roof using a corrugation board.

Also, D is a pantograph, E is an air conditioner, F is a shelf, G is a strap, H is a seat, K is a floor, and L is a wheel. FIG. 2 is a cross-sectional view of a corrugation board coated with the polyurethane roofing material of the present invention, where X is the corrugation board, P is the primer layer, Q is the spray coating of the polyurethane roofing material, and R is the spray coating of the polyurethane roofing material. is a finishing spray coating. Third
The figure is an explanatory cross-sectional view of the corrugation plate including spot welds S. (1) Pretreatment including substrate preparation Roof substrate substrate preparation involves creating a surface condition that allows the polyurethane coated roofing material 2 coating to adhere completely and maintain long-term durability. is necessary.

That is, (1) the surface of the base substrate is cleaned to improve the adhesion and wetting of the coating film.

(4) Surfaces that are too smooth are appropriately roughened.

(110 If the surface of the base is uneven, treat it appropriately to flatten the surface. IV) In order to inert (stabilize) the metal surface and prevent corrosion under the paint film, apply a primary primer treatment. It is assumed that you have done so.

(Because construction progresses mainly in the vehicle manufacturing process, it may not always be possible to set up an ideal process for the roof painting process after the primary primer treatment. In that case, start with the secondary primer.) 2) Secondary Primer (application of base coat) Brush a one-component urethane primer onto the base surface that has been pretreated including surface preparation.

The coating amount is 100 to 1509/M2. 3) Spray coating of polyurethane-coated roofing materials (hot spray method) (1) Spray coating roofing materials Components B and A are heated separately to 40 to 55°C (using a heater), but they are added under pressure. If so, the temperature range may be lowered, and the viscosities of the B component and A component of the polyurethane coated roofing material for the Souvre method in each temperature range are as shown in Table 1.

(Ii) A schematic diagram of the configuration of a two-component airless spray coating machine is shown in FIG.

1 and 2 are raw material filters, 3 is the main component (B component), 4 is a curing agent (A component), 5 is a pump, 6 is a static mixer, 7 is a spray gun, 8 is a cleaning liquid pump, 9 is a cleaning liquid 10 and 11 are raw material heating heaters.

The spraying machine and operating conditions are as shown in Table 2.The method for applying a uniform film thickness is to move the spray gun back and forth 4 to 5 times toward the surface to be coated, and apply the film to a uniform thickness of 1 to 2 meters. do. (
4) Regarding the application of finishing coat D, mix a non-yellowing acrylic elastic urethane paint in the following ratio and apply with a brush or spray.

The main agent is a colored liquid mainly made of acrylic polyol, and the curing agent is a liquid mainly made of aliphatic isocyanate, which are mixed in a 1:1 mixing ratio (dynamic amount) and applied.

The coating amount is 100 to 2001/7TI. Examples of blending materials used in the present invention will now be described in detail.

First, undercoat! 2 (Secondary Primer) is a one-component polyurethane fly with a formulation within the range shown in Table 3. Next, regarding the two-component cold-curing polyurethane resin composition, which is the most important part of the present invention, which undergoes a curing reaction from a thixotropic state accompanied by rapid viscosity changes, the B component is determined according to the following table 4. be.

Ingredient A is as shown in Table 5. The NCO content after mixing the above and reacting and aging at 90℃ for 3 hours in one step is 3.9 ~
The prepolymer isocyanate composition is 4.8.

The on-site mixing ratio is 2/1 (volume ratio) for component B/component A.
The interval (time) until a thixotropic state is reached after mixing the two liquids is 20 seconds to 90 minutes at 40 to 45 degrees Celsius.
seconds, the time from a thixotropic state to a cured state where you can walk on the coated surface is 1:1 when using the main agent in Table 6 and the curing agent in Table 7, and the coating amount is 100 to 2009/I. do.

The formulation used in the spray coating method of the present invention can also be used for troweling with only slight changes in the composition shown in Table 4.

Regarding the composition, only the amount (1) in Table 4 is changed. Trowel coating can be used for filling grooves in corrugation boards.
As shown in Fig. 5, when the smooth surface obtained by filling and pasting the grooves of the corrugation plate or by filling and applying a lightweight resin compound is used as the base state, after the primer treatment, as in the case where the flat steel plate is used as the base, Following the spray coating of the two-component mixture of A and B, a non-yellowing acrylic elastic urethane composition is spray-coated. In this case, troweling is suitable for filling the grooves in the corrugation board. In Figure 5, X is a corrugation board, P is a one-component urethane primer, Q is a two-component cold-curing polyurethane spray coating, and R is non-yellowing acrylic. It is 12 to 20 hours. Next, the finishing paint was a non-yellowing acrylic urethane paint whose main ingredient composition was as shown in Table 6.

This was emulsified for 60 minutes using a Homomixer 2S type manufactured by Tokushu Kikasha.

Further, the composition of the curing agent added to the composition in Table 6 is as shown in Table 7. The ratio is 2:1, and the time it takes to reach a thixotropic state after mixing the two liquids is 5 to 7 minutes at room temperature (25°C), and the time from which it takes to harden is 12 to 20 hours. To fill the grooves of the corrugation plate, as shown in FIG. 5(a), a back-up material U made of urethane foam molding is adhered to the grooves of the corrugation plate using a one-liquid urethane adhesive T.

The bulk specific gravity of this filled part is 0.13 to 0.25, and the hardness is JI
SA is 24-25. In addition, as shown in the same figure (b), the styrene foam hollow sphere V is coated with 200% B component of the component for applying with a trowel.
100 parts (or more parts by weight) of component A and 600 parts by volume of styrene foam spheres V are mixed, and after 5 to 7 minutes, the viscosity changes rapidly and becomes a thixotropic state that is effective in preventing sagging. Fill the groove with a light weight resin compound and apply with a trowel to create a smooth surface. This filled part has a bulk specific gravity of 0.
4 to 0.5, and hardness JISA 4O to 50. The viscosity of component B used in this composition is 610 at room temperature (25°C).
0cps. The A component is 5000 cps. In addition, the compounding contents of Q' in the case of FIG.
After 5 to 7 minutes after mixing 60 parts, a lightweight resin compound that changes in viscosity rapidly and becomes a thixotropic state effective for preventing sagging is filled into the grooves of the corrugation board, and the surface is smoothed by applying with a trowel. do. This filled portion has a bulk specific gravity of 0.6 to 0.8 and a hardness of JISA 55 to 65. (
0) In the case of Figures and (C) Figures, 1
Next, apply primer Y. Once this filling is completed, the aforementioned primer layer P, two-component urethane layer Q, and finishing non-yellowing acrylic urethane layer R are finished by the aforementioned spray coating. FIG. 6 shows the state of viscosity change after mixing components A and B of the spray-type polyurethane-coated roofing material used in the present invention.

a is the one of the present invention, b is for the trowel coating of the present invention, c
shows the case of conventional non-sag type polyurethane-coated roofing material. In the figure, the thixotropic state of the coating roofing material used in the present invention can be seen at around 80,000 Cps, and sagging is prevented. Table 8 shows the physical properties of the coating film of the small urethane coated roofing material of the present invention and the results of measuring changes in viscosity (viscosity) from the two-component mixture.

[Brief explanation of the drawing]

Fig. 1 is an explanatory cross-sectional view of a vehicle coated with the polyurethane roofing material of the present invention by the spray method, and Fig. 2 is an explanatory cross-sectional view of a corrugation board coated with the polyurethane roofing material of the present invention. FIG. 3 is a cross-sectional explanatory diagram when the spot welding part of the corrugation plate is included, FIG. 4 is a schematic diagram of the configuration of a two-component airless spray coating machine, and FIG. 5 is a cross-sectional explanatory diagram when the groove of the corrugation plate is filled. 6th
The figure is a graph showing the change in viscosity of the urethane roofing material after mixing in the present invention. P... Primer, Q, Q'... Polyurethane roofing material coating, R... Non-yellowing acrylic elastic urethane paint, S... Corrugation board Spot weld, T...Adhesive, U...
・Urethane foam molding backup material, V...Styrene foam sphere, X...Corrugation board, Y...Primary primer, Z...Pearlite, 1, 2... Raw material filter 1, 3...
...Main component (B component), 4...Curing agent (A component), 5...Pump, 6...Static mixer, 7... ...Spray gun, 8...
...Cleaning liquid pump, 9...Cleaning liquid, 10,1
1... Raw material heating heater.

Claims (1)

[Claims] 1 When spraying a coating film on the structural surface of a railroad car roof that has a sloped outer shell made of welded steel plates, especially corrugated steel plates, thixotropic coating, which flows and adheres to the object in a low viscosity range and causes a sudden change in viscosity, is applied. A two-component room-temperature-curing polyurethane resin composition that cures from the state is spray-painted on the object, making it possible to prevent sagging while achieving sufficient functionality for vehicle roofs with a uniform thickness that follows the shape of the vehicle roof substrate. A method for applying a coating film for a railway vehicle, the method comprising forming a coating film having the following properties.