JPH0824781A - Method for coating hull block - Google Patents

Abstract

PURPOSE:To shorten the time of works and to reduce cost by shotblasting a steel sheet, spray-coating only the necessary part of the sheet with the polyurethane-base paint and amine catalyst, drying the sheet, cutting the sheet and welding the relevant sheets to form a block. CONSTITUTION:When a hull block is coated, a steel sheet is firstly shotblasted or pickled and then shop-coated with a primer or chemical conversion-coated, and only the part of the sheet to be double side-coated is spray-coated with a polyurethane-base paint quickly curable in the presence of an amine catalyst and the amine catalyst by using a spray gun moved under numerical control, and the paint is cured at ordinary temps. The sheet is then cut to a specified shape under numerical control, and a relevant steel sheet is welded to the part not coated with the paint to form a block. The block is then secondarily primer- coated and secondarily coated. Consequently, the time of works is shortened, the production cost is reduced, and the manpower is saved by full automation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating hull blocks.

[0002]

2. Description of the Related Art Conventionally, in the construction of ships, steel plates are first shot-blasted, then the shop primer coating, steel plate cutting / bending, block assembly, block secondary coating, and outfitting work are performed in sequence. It is being appreciated. In these processes, when undercoating and overcoating are performed after the block is assembled, the parts that have been damaged by cutting and bending of the steel plate and welding during the block assembly and exposed outdoors are red rust and white rust. The secondary surface treatment is performed in advance on the portion where is generated. This secondary surface treatment work requires heavy labor and high place work in a dirty work environment, and is very costly. Further, since the work is performed outdoors, there is an inherent problem that it is easily affected by the weather and the work cannot be leveled. As a method to solve these problems, as shown in the process block diagram of FIG. 2, the electrostatic powder coating is applied to the entire surface of the steel plate coated with shop primer, and then the unnecessary portion of the powder coating is applied. Is removed through a suction nozzle that moves under NC control, then baked, then this steel plate is cut into a predetermined shape by NC control, and a steel plate is welded to the unpainted part to form a block. (For example, Japanese Patent Laid-Open No. 5-200359).

[0003]

According to the block coating method for a hull described above, use of NC control saves labor and manpower, recovers uncoated powder coating, improves coating efficiency by reuse, and eliminates solvent. The effect of improving the work environment by not using it can be obtained. However, according to the above-mentioned block coating method for a hull, a step of coating electrostatic powder coating on the surface of a steel plate coated with shop primer, a step of removing unnecessary powder coating by NC control, and a step of baking powder coating. Then, the process is transferred to the cutting process under NC control through the three processes. It takes 30 minutes to 90 for 3 steps from coating of powder coating to baking.
Since it requires an extra long time and has the drawback of extending the process, baking by high frequency induction heating is performed to shorten the process. According to this heating method, the baking time is shortened, but there is a drawback that a large amount of heat energy is required. Furthermore, this method requires a process that requires time and effort to collect the powder coating material in the unpainted portion, which is contradictory to the omission of the process and energy saving, and its improvement is strongly desired.

[0004]

The present invention has been proposed in view of such a situation, and provides a method for coating a hull block which is effective in shortening the construction period, reducing the production cost, and saving labor and labor through full automation. It is intended to be provided. The present invention provides "1. directly after shot blasting or pickling treatment,
Or, after applying shop primer coating or chemical conversion coating, polyurethane coating and amine catalyst that cures rapidly in the presence of amine catalyst through a spray gun that moves by NC control only on the parts that require coating on both sides of the steel sheet. Coating drying step of spray coating and curing at room temperature; the steel sheet that has undergone the coating and drying step is cut into a predetermined shape by NC control, and the related steel sheet is welded to the uncoated portion of the polyurethane-based coating to form a block. And a step of subjecting the block to a secondary base treatment and then applying a secondary coating, the coating method of the hull block. 2. The method for coating a hull block according to Item 1, wherein the spray coating of the polyurethane-based paint and the amine catalyst is a method in which vapor or mist of the amine catalyst is contained in spray air to perform spray coating. 3. The method for coating a hull block according to item 1 or 2, wherein the polyurethane coating is applied by leaving the portions corresponding to the cut portion and the welded portion of the steel sheet unpainted. 4. The method for coating a hull block according to any one of items 1 to 3, wherein the coating mist in the spray coating of polyurethane coating is cut by using shaving air to prevent the coating mist from adhering to an unnecessary coating portion. Regarding The present invention will be specifically described below.

[0005]

According to the present invention, as shown in the process block diagram of FIG. 1, shot blasted or pickled regular length steel sheets are subjected to shop primer coating or chemical conversion coating treatment, and then wet on wet system. At this point, a polyurethane-based paint which quickly cures in the presence of amine is applied to a necessary portion of the paint through a spray gun which moves by NC control. That is, the cut portion, the welded portion, and the bent portion of the steel plate, which is performed in the subsequent process, are applied in a form that remains unpainted. The polyurethane-based paint is fast-curing and cures at room temperature in 1 to 5 minutes.

Then, the steel sheet coated with the polyurethane paint is cut into a predetermined shape by NC control in the same manner as in the construction of a conventional hull, and the steel plates concerned are welded to the unpainted portion of the polyurethane paint to form the middle block. Then, a plurality of medium-sized blocks are welded to form a large-sized block.
The large set block is subjected to a secondary base treatment and then subjected to secondary coating to form a total set block.

The present invention relates to a method for forming an uncoated portion by applying a powder coating material on the entire surface, which is carried out in a conventional coating and drying step, and removing an unnecessary portion of the powder coating material through a suction nozzle. Instead, it has a major feature that is different from the conventional one in that a polyurethane-based coating material which is rapidly cured at room temperature in the presence of amine is applied to only a necessary portion by NC control to form an uncoated portion.

As the above-mentioned polyurethane-based coating material, a conventionally known coating material can be used (for example, Japanese Patent Laid-Open Publication No. Sho 5).
8-53345, JP-A-58-78737, JP-A-6
1-278871, JP-A-62-236816). This coating is a type of coating that uses a reaction between a hydroxyl group and an isocyanate group or a reaction between a thiol group and an isocyanate group to cure rapidly in the presence of an amine, particularly a tertiary amine such as dimethylethanolamine. If you mix and paint in advance, the coatable time is short, so
It is applied by a coating method called a vapor injection cure (VIC) method in which a tertiary amine vapor is contained in spray air, or a mist injection cure (MIC) method in which a tertiary amine mist is contained in spray air.

The polyurethane paint must be applied only on the portion of the surface of the steel sheet that has been subjected to the shop primer coating that needs to be coated, that is, the portion corresponding to the cut portion and the weld portion of the steel sheet is left unpainted. Such coating is performed by using a spray gun that can be automatically moved by NC control and can cut the coating mist by shaving air to almost 100%, and there is no coating mist in the uncoated portion. To be done. The coating film thickness (dry) of the polyurethane-based paint is generally in the range of 50 to 300 μm, and the coating film cures at room temperature in 1 to 5 minutes. Thus, the steel sheet coated with the polyurethane-based paint is cut into a predetermined shape by NC control, the middle set is cut into a large set, the secondary base treatment is performed, the secondary coating is performed, and then the entire set is performed.

[0010]

EXAMPLE A VIC coating process under NC control, which is a feature of the present invention, will be described.

Example 1 Shot-blasted steel plate (3 m × 15 m) was
A shop primer (manufactured by Kansai Paint Co., Ltd., trade name: SD Zinc # 1000HA (S)) was applied, and a polyurethane paint having the following composition was applied by a wet-on-wet method according to the application process shown in FIG. [Polyurethane coating composition] Pentaerythritol tetrakis- (β-thiopropionate) obtained by esterification reaction of mercaptobropionic acid and pentaerythritol 25 parts by weight Titanium white 4.5 parts by weight Carbon black 0.5 parts by weight Talc 35 parts by weight Xylene 7 parts by weight Diphenylmethane 4,4'-diisocyanate 28 parts by weight Total 100 parts by weight The polyurethane paint is applied by spraying dimethylethanolamine generated by the VIC method at a concentration of 100 in the spray air.
After adjusting so as to be ppm, it was applied in a predetermined pattern by NC control using an air spray gun capable of cutting the coating mist with shaving air so as to leave the weld melted portion uncoated. After coating, the coating film was cured by leaving it at room temperature for 3 minutes, and the steel sheet was ready for the next step. The performance of the polyurethane coating film is as shown in Table 1 below.

Example 2 The same procedure as in Example 1 was carried out except that the shop primer was not used and the polyurethane paint was directly coated on the shot-blasted steel sheet. The performance of the polyurethane coating film is as shown in Table 1 below.

Comparative Example 1 Instead of the polyurethane paint used in Example 1, an epoxy powder paint (trade name: EVACLAD 3000) manufactured by Kansai Paint Co., Ltd. was applied according to the painting process shown in FIG. The unnecessary portion of was removed through the suction nozzle. Then, it was cured at 170 ° C. for 20 minutes. The performance of the cured coating film is as shown in Table 1 below.

Comparative Example 2 The same procedure as in Example 1 was repeated except that a tar epoxy coating (Kansai Paint Co., Ltd., trade name: Eposir 600) was used in place of the polyurethane coating. The performance of the tar epoxy coating film is shown in Table 1 below.

[0015]

[Table 1]

Note 15 Soak in a 15% sodium chloride aqueous solution.
Items without rust and blisters are displayed as good. Note 2: Immersion test at room temperature for 3 weeks under the condition of adding 1500 mV. Good with a small creep penetration width. Note 3 Keep at 60 ℃, pH 3 ± 3 with sodium hydroxide.
Immerse in a solution of the following composition adjusted to 0.2 for 1 month. Items without rust and blisters are displayed as good. Sodium chloride 50g Acetic acid 10ml 30% Hydrogen peroxide 5g Water 1000ml Note 4 Sulfur content 2 to 2.4%, viscosity 15 to 16 centipoise / 30 ° C and specific gravity 0.877 to 0.879 (20 ° C)
Soaked in crude oil of Khafji. Items without rust and blisters are displayed as good.

[0017]

In the present invention, the three steps (comparative example) of the electrostatic powder coating step, the NC powder removing step and the powder coating baking step shown in FIG. 2 are performed by the VIC or MI by NC shown in FIG.
By substituting the C coating process (example), a baking device as in the case of powder coating is not required, so that energy saving can be achieved and the process can be shortened. Moreover, in terms of coating film performance, polyurethane-based paints exhibit the same performance as conventional powder paints. Further, by adopting the present coating method, there is an excellent effect that it becomes possible to perform pre-coating by super fast curing at room temperature.

[Brief description of drawings]

FIG. 1 is a process chart for constructing a hull showing an embodiment of the present invention.

FIG. 2 is a conventional hull building process diagram.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B05D 3/10 F 7415-4F A 7415-4F 3/12 B 7415-4F 7/24 301 V 7415 −4F 302 T 7415−4F (72) Inventor Ayichiro Toyoda 33-1 Kanzakicho, Amagasaki City, Hyogo Prefecture Kansai Paint Co., Ltd. (72) Inventor Toshiaki Ishikawa 4-17-1 Higashihachiman, Hiratsuka City, Kanagawa Prefecture Kansai Paint Co., Ltd. (72) Inventor Nobuhisa Toda 33-1 Kanzaki-cho, Amagasaki City, Hyogo Prefecture Kansai Paint Co., Ltd.

Claims (4)

[Claims] 1. After shot blasting or pickling treatment,
Directly, or after applying shop primer coating or chemical conversion coating, only on the parts of the steel sheet that require coating,
A coating / drying step of spray-coating a polyurethane-based paint that is rapidly cured in the presence of an amine catalyst and an amine catalyst through a spray gun that moves under NC control, and curing at room temperature;
The step of cutting the steel sheet that has undergone the coating and drying step into a predetermined shape by NC control, and welding the relevant steel sheet to the unpainted portion of the polyurethane-based coating to form a block; A method for coating a hull block, which comprises the step of applying a subsequent coating. 2. The method for coating a hull block according to claim 1, wherein the spray coating of the polyurethane-based paint and the amine catalyst is a method of spray coating in which vapor or mist of the amine catalyst is contained in spray air. 3. The method for coating a hull block according to claim 1, wherein the polyurethane coating is applied by leaving unpainted portions corresponding to the cut portion and the welded portion of the steel sheet. 4. The coating of the hull block according to claim 1, wherein the coating mist in the spray coating of the polyurethane coating is cut by using shaving air to prevent the coating mist from adhering to an unnecessary coating portion. Method.