JPH0356176A - Painting method for finishing outer surface of two-piece can body and outer surface finish-painted two-piece can - Google Patents

Abstract

PURPOSE:To obtain an outer surface finished two-piece can excellent in the combination of abrasion resistance and pasteurization resistance by using a gravure roll wherein deep carving is applied to the whole of the peripheral parts corresponding to both upper and lower end parts of a can bdyy and shallow carving is applied to the whole of the peripheral part correspond to the central part thereof. CONSTITUTION:The top coat paint 50 of a gravure roll surface 42A is transferred to a coating roll surface 40A to be supplied to a can 10. The gravure roll surface 42A is divided into regions A' are arranged on both sides of the regions B' and the width of the region B' is almost same to the length of the central part of a two-piece can. The carving depth of the regions A' is set, for example, to 105 - 115mum and the carving depth of the region B' is shallower than said depth to be set, for example, to 85 - 95mum. The top coat paint 50 is respectively taken in the regions A', B' of the roll in predetermained amounts corresponding to the depth difference of carving to be transferred to a coating roll 40. The transferred paint 50 is leveled by a scraper roll to be applied to the outer peripheral surface of the can.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a two-piece can exterior finishing coating method and the two-piece can, and more specifically, to a method for coating the exterior surface of a two-piece can, and more particularly, to a method for painting the exterior surface of a two-piece can, and more specifically, to provide a method for painting the exterior surface of a two-piece can, and more specifically, to provide a method for painting the exterior surface of a two-piece can. The present invention provides a two-piece can with excellent durability and pasteurization resistance, and also relates to a method of painting the exterior surface of such a two-piece can.

(Prior technology) Two-piece cans (seamless cans), which are formed by drawing and ironing metal materials between dies and punches, have no seams on the sides of the can body and can be printed on the entire can body, giving it a beautiful appearance. Because of its superior properties, it is widely used as a pressure-resistant can for containing contents that have their own pressure, such as carbonated drinks and beer.

Unlike regular two-piece cans, this two-piece can is difficult to paint or print on the metal material before it is formed, so each can body must be painted after it is shaped. It won't happen. For example, the painting of two-piece cans is
As described in Japanese Patent No. 712, this is done by bringing the side wall of the can body into contact with a roller coated with paint.

By the way, when transporting, cartoning, and transporting empty cans at a can manufacturing factory, and when transporting empty cans or actual cans at a cannery, contact between can bodies or contact with transport equipment may occur. Abrasion scratches (scratches) on the paint film are likely to occur,
In addition, in the pasteurization process of filled canned goods,
Tends to scratch the paint film. In order to prevent the occurrence of such scratches, it is widely practiced to apply an external finishing paint to the upper surface of the painted print layer.

(Problem to be solved by the invention [) However, applying an external finishing paint with a sufficient film thickness to prevent scratches on the painted printed surface will only lead to an increase in can manufacturing costs due to an increase in the amount of paint used. In addition, the problem of environmental pollution due to an increase in the amount of mist generated during paint baking and the increase in pollution prevention costs for collecting the mist arise. On the other hand, in the field of can manufacturing, there is a constant demand to reduce can manufacturing costs, and it is essential that this cost reduction be done without substantially reducing the various performances of cans. .

Therefore, an object of the present invention is to provide a two-piece can with an exterior finish that has an excellent combination of abrasion resistance and pasteurization resistance, while having the minimum necessary exterior finish coating on the painted printed surface of the two-piece can body. An object of the present invention is to provide an exterior finishing coating method for this purpose.

Another object of the present invention is to provide a two-piece can, in which the outer surface of the two-piece can body is coated with outer finishes of different thicknesses in a uniform distribution, which has excellent resistance to various properties and reduces can manufacturing costs, and a coating method therefor. is to provide.

Still another object of the present invention is to provide a method for applying an external finish coating having the above-mentioned thickness distribution by one roller application. (Means for Solving the Problems) According to the present invention, an outer surface finishing paint is applied to the transfer roll,
After transferring the paint on the roll to the coating roll,
In a two-piece can body outer surface finishing coating method that involves applying paint to the printed two-piece can body outer circumferential surface, the transfer roll is applied to a surface of the can body with deep engravings applied to the entire circumferential portion corresponding to both the upper and lower ends of the can body. A gravure roll is used that has a shallow engraving applied to the entire circumference corresponding to the center of the can body, and the gravure roll is used to apply a thick coat of external finishing paint to both the upper and lower ends of the outer peripheral surface of the two-piece can body, and to coat the outer surface in the center. To provide a method for finishing the outer surface of a can body, which is characterized by applying a thin layer of finishing paint.

According to the present invention, the two-piece can body is provided with an outer surface finish coated two-piece can in which the outer peripheral surface of the two-piece can body is provided with a printing layer and a transparent outer surface finish coating layer thereon.
To provide a two-piece can with exterior finish coating, characterized in that a coating film is formed so that the exterior finish paint is thick at both upper and lower ends and thinner at the center. (Function) The present invention has the following characteristics: the thickness of the exterior finish coating required from the viewpoint of protection of the printed surface of ordinary paints and scratch resistance, and the thickness of the exterior finish coating required from the standpoint of pasteurization resistance and abrasion resistance. There is a difference between the two, and the former can be much smaller than the latter.Moreover, in painted two-piece cans, the parts where the paint film peels off during pasteurization or where unreflection scratches occur during transport are Therefore, if the outer finishing coating is partially thickened in these parts of the can body, it is possible to create a can that is satisfactory in terms of protection of the painted printing surface and both durability. This is based on the knowledge that this can be achieved using the minimum amount of paint required.

Figure 6 of the attached drawings shows the lower part of the can body and the can when the thickness of the outer surface finish coating of a two-piece can (250ml can) was changed and this was pasteurized (in hot water at 80°C for 30 minutes). This is a plot of the relationship between the amount of coating film and the number of peeled cans (%) at the top of the body and the center of the bottom of the can. Also, the seventh
The figure also shows the amount of coating film and defects on the lower part of the can, the upper end of the can body, and the center part of the can body when the thickness of the outer surface finish coating of two-bead cans was changed and these cans were subjected to vibration tests. The relationship with the attached area (mm2/can) is plotted.

According to these results, in the center of the can body, the amount of coating film has almost no effect on the occurrence of scratches due to coating peeling or abrasion during pasteurization treatment, and the thickness can be kept to a minimum. This indicates the fact that the thickness of the finish coating has a large effect on the upper and lower ends of the can body, and that the thickness of the coating must be considerably larger than that at the center of the can body.

In the present invention, by providing a thick outer finishing coating on the upper and lower ends of the two-piece can body and a thinner coating on the center, the amount of paint used is kept to the minimum necessary, while the painted printing surface is applied to the entire can body. While providing protection, it is also given pastrise resistance and abrasion resistance.

The present invention further provides that when applying an external finishing paint to the outer surface of a two-piece can body that has been painted and printed, deep engravings are applied to the circumferential portions corresponding to both the upper and lower ends of the can body, and shallow engravings are applied to the circumferential portions corresponding to the center portion. The present invention is also based on the knowledge that when a gravure roll coated with the above coating is used, a two-piece can with an outer surface finish having the above-mentioned film thickness distribution can be obtained with one coating.

Conventionally, a coating roller that forms a coating film with a normal thickness and a partially thickened coating film in a single coating operation has a smooth circumferential surface, a coating work surface with a certain normal thickness, and an arch-shaped notch. It is known that the coating roller has a thick application work surface consisting of (Japanese Patent Publication No. 58-19349 No. 9!); When the groove is simply deepened (Table 1 of the same publication, No.
3 and Fig. 3 C), there are extremely large variations in the thick coating film, and there are also significant coating film defects such as misting and entrapment of air bubbles, whereas in the present invention, a gravure roll is used. Applying finishing paint to a gravure roll, which has deep engravings on the entire circumferential part corresponding to the upper and lower ends of the can body and shallow engravings on the entire circumferential part corresponding to the center part of the can body,
After the paint on this gravure roll is once transferred to a coating roll, it is applied to the 2-bead can body to create an external finish coating with a predetermined thickness distribution without the aforementioned defects. This makes it possible to form on a painted printing surface. To further explain this feature, the outer circumferential surface of the two-piece can body rolls into contact with a coating roll to apply the finishing paint, and the coating roll rolls into contact with a transfer roll from which paint is supplied (transferred). With conventional transfer rolls, the finish paint could only be transferred uniformly to the coating roll, and it was also difficult to adjust the amount of finish paint supplied, but by using a gravure roll as the transfer roll, it was possible to transfer the finish paint to the coating roll evenly. The amount of top coat supplied can be precisely and finely adjusted. In other words, the amount of paint supplied can be increased by increasing the engraving depth or number of lines (engraving cell volume!) on the coating roll surface that makes rolling contact with the outer peripheral surface of both ends of the two-piece can, and on the gravure roll surface that makes rolling contact with this roll surface. The depth of the engraving on the surface of the gravure roll was made shallower in the other central areas, and fine adjustments were made to reduce the amount of paint supplied. Adjusting the amount of paint using such a gravure roll is easier to set than conventional adjustment of the gap between the transfer roll and the suction roll, and it is possible to reliably set the amount within the range of the coating amount of the top coat mentioned above. It can also be accurately supplied to the desired position on the surface of the coating roll. Therefore, in the top coating process for two-piece cans,
By using a gravure roll having the above-mentioned characteristics, a two-piece can can be easily and reliably coated with a thick top coat on both upper and lower ends, thereby providing the above-mentioned excellent two-piece can.

(Preferred Embodiments of the Invention) Preferred embodiments of the two-piece can body exterior finish coating method and the exterior finish coated two-piece can according to the present invention will be shown below with reference to the accompanying drawings. Note that the present invention is not limited to the use of the coater device shown in the embodiments shown below.

FIG. 1 is a sectional view of a two-piece can used in the present invention. As shown in the upper figure, the upper end 12 of the two-piece can 10 is necked in, and a printed layer is formed on the outer peripheral surface of the two-piece can 10. Upper and lower corners 12 and 14 of a two-piece can
Area A in the vicinity is often subjected to 9M impact during handling during can manufacturing, etc., while the outer circumferential surface of the central portion of the two-piece can is area B, which does not receive much impact.

FIG. 2 is a schematic explanatory diagram of a coater device in which the outer periphery coating method for two-piece cans according to the present invention is used.

As shown in FIG. 2, a can supply conveyor 18 is connected to the left of the coater device 16, and the two-piece cans 10, 10, . . . are loaded onto the supply conveyor 18 from a transport line (not shown). The cans 10 on the supply conveyor 18 are connected to the set drum 20
The liquid is sent to the spindle m mechanism 22 through which the can 10 can be rotatably held. The spindle mechanism 22 is provided around the outer circumference of a disc-shaped turn desk 24 at predetermined intervals, and
0 is conveyed according to the rotation of the turn desk 24 (arrow A in FIG. 2).

A coating head machine vI 126 is arranged adjacent to the turn desk 24, and the coating head mechanism 26 is provided with a coating roller 40. The can 10 held by the spindle mechanism 22 comes into rolling contact with the coating roller 40, and a top coat (external finishing paint) is applied to its outer peripheral surface.

The coated can 10 is transferred to a transfer drum 28.30,
32, 34, and are sequentially conveyed to subsequent steps (not shown).

3 and 4 are explanatory diagrams of the inside of the coating head mechanism 26 in which the coating method according to the present invention is used, and a gravure roll 42 is rolled into contact with the coating roll 40 in addition to the can 10. A scraper 46 and a supply head 48 are arranged on the gravure roll 42 . A top coat 50 is supplied to the supply head 48, and the top coat 5o is supplied to the gravure roll 4.
As the number 2 rotates, the number 1 is supplied to the roll surface 42A, and the excess amount is removed by the scraper 46. The top coat 50 on the gravure roll surface 42A is transferred to the coating roll surface 40A and then applied to the can 10. As shown in the tJS diagram, the gravure roll surface 42A is divided into areas A' and B' depending on the engraving depth, and the boundary surfaces 54 and 54 thereof are flat.

Area A' is arranged on both sides of area B', and the width of area B' is approximately the same as the length of the central portion of the two-piece can to which it is applied.

The depth of engraving in area A' is preferably in the range of 105 to 115 μm, particularly preferably in the range of 107 to 113 μm. In addition, the engraving in area A' has a plurality of grooves with triangular cross sections (
The groove density is preferably in the range of 78 to 82 lines/inch. The depth of engraving in region B' is shallower than region A', and is preferably in the range of 85 to 95 μm, particularly preferably in the range of 87 to 93 μm.

Furthermore, the engraving in region B' is made up of a plurality of grooves (diagonal cells) having a triangular cross section, and the groove line number density is preferably in the range of 88 to 92 lines/inch. The amount of paint deposited per unit in area A' is preferably in the range of 1.4 to 1.8 times the amount of paint deposited per unit in area B'.

The paint adhering to these areas A' and B' is applied to positions corresponding to areas A and B on the outer peripheral surface of the two-piece can via coating rolls 40, respectively, as shown in FIG. In FIG. 5, the engraving is a diagonal groove, but the engraving is not limited to this, and the engraving may be in the shape of a so-called square pyramid or a rectangular lattice.

The boundary surfaces 54, 54 are flat parts that are not engraved, and since the areas A' and B' are theoretically engraved, this flat part has the same height as the tops 56, 58 of the engraved parts shown in FIG. must become. However, the top 56.58
is raised during engraving, so the boundary surface 54 tends to be lower than the top. For this reason, paint 5 is also applied to this boundary area.
0 adheres, and the paint does not break off at the boundary during transfer to the coating roll. Further, it is preferable that the width of the boundary is in the range of 1 to 5 mm, and if there is no flat surface at the boundary, when the paint is applied to the can 10, areas A and B on the outer circumferential surface of the can are There is a risk that there will be a step at the border and the coating will not be applied smoothly. On the other hand, if the boundary part has a flat width within the above range, the paint near the boundary part is coated through the coating roll 40, taking advantage of the fact that the paint is applied to the flat boundary part surface as described above. 10 cans
It is formed with an intermediate film thickness at the boundary between areas A and B, and the coated surface is not interrupted at the boundary, and conversely, there are no steps and a smooth surface.

The can material for the two-piece can used in the present invention includes tI
Various surface-treated steel plates such as Itil gold steel plate and tain-free steel (electrolytic chromic acid treated steel plate) and light metals such as aluminum are used. The coating method according to the present invention is particularly preferably applied to thin-walled deep-drawn cans in order to make the cans lighter.This is because the center of such cans is easily bent and deformed, but the upper and lower corners are This is because there is almost no deformation, and as shown in FIGS. 6 and 7, there is no #J separation property at all in the central part, and the Ij4Jm properties are high in the upper and lower parts.

As the top coat, a so-called finishing varnish or the like is used, and specifically, epoxy-based paint, epoxy acrylic paint, epoxy ester paint, etc. can be used. The solid content of these top coatings varies slightly depending on the type, but it is desirable that the solid content is in the range of 55 to 65%, and it depends on the depth of the engraving of the gravure roll and the shape of the smooth surface at the boundary. It is something.

When the gravure roll 42 configured as described above is used, the A' and B' areas of the roll are coated with top coat 50.
A predetermined amount of the engraving is taken in according to the depth difference of the engraving, and transferred to the coating roll 40f. Transfer paint 5
0 is smoothed by a scraper roll 44 and coated on the outer circumferential surface of the can, especially in such a manner that there are no steps on the boundary surfaces of the regions. At this time, the amount of paint in area A at both the upper and lower ends of canner 0 is preferably in the range of 70 to 100 mg/drrr, particularly preferably 25 to 85 mg/drrr.

Furthermore, the amount of paint in the central area B of the can 10 is 45 to 65 m.
It is desirable that it is in the range of g/dbo, especially 50 to 6
0■/drr? is desirable. The ratio of the thickness of area A to the thickness of area B is (A/B) 1.3/1 to 1. It is desirable that it be 8/1.

In addition, it is preferable that the boundary paint has a thickness intermediate between the thickness of area A and the thickness of area B. According to such a coating method, the boundary area becomes an intermediate thickness layer, and the boundary area is smooth and coatability is improved. becomes good.

(Effects of the Invention) According to the present invention, a gravure roll is used as the transfer roll in the two-piece can exterior finishing coating method, and deep engravings are applied to the portions corresponding to the upper and lower ends of the can body, and the central portion of the can copper Since we used the gravure roll with shallow engravings on the parts corresponding to the two-piece can body, it was easy to apply a thick coating of the external finishing paint to the upper and lower Wi@ parts of the outer peripheral surface of the two-piece can body, and a thin coating of the external finishing paint to the central part. You can make sure. Moreover,
In this method, the amount of external finishing paint applied to both the upper and lower ends can be adjusted accurately, and it is possible to create an accurate difference in the amount of paint applied to the upper and lower outer circumferential surfaces of the can and the outer circumferential surface of the center portion. In addition, a two-piece can with a thick topcoat on both the top and bottom ends and a normal thickness on the center will have excellent pasteurization resistance and abrasion resistance during transportation.Moreover, when the above method is used, Since the paint in the central part is made as thin as possible without causing abrasion, it is possible to provide a product at a lower cost than in the past. Furthermore, minimizing the amount of paint used helps prevent the occurrence of mist and the like.

(Example) Examples of the two-piece can outer surface finish coating method and the coated can according to the present invention will be described below. Note that the present invention is not limited to this.

Example 1 Using the coating head structure shown in FIG. 3, a gravure roll was formed with a width of region B at the center of the roll being 80 mm, and regions A at both ends of region B having a flat border of 5 mm. The engraving in area A was of a diagonal line type, with a number of lines of 80 and a depth of 120 μm.

The engraving in area B was of the diagonal type, with a number of lines of 95 and a depth of 90 μm.

The two-piece can used was a 250o1 bright can, and the paint used was F40-14OA (actually measured solid content: 60.3%).

As a result, Table Y shows the amount of coating in area A at both the upper and lower ends of the two-piece can, the amount of coating in area B at the center, and the amount of coating at the border. In addition, all the boundaries on the surface of the can were smooth in appearance. Furthermore, the number of peeled cans in the vortex (80°C for 30 minutes) was 0.
It was less than 1%. The flawed area by vibration test is lmI
It was 112 or less.

Table 1 In addition, the thickness of the boundary area was measured using the β-ray method and converted to the coating amount.

[Brief explanation of drawings]

Fig. 2 is a cross-sectional view of a two-piece can used in the present invention, Fig. 2 is an explanatory diagram of a rotor device in which the method for painting the outer circumferential surface of a two-piece can according to the present invention is used, and Fig. 3 is a cross-sectional view of a two-piece can used in the present invention. An explanatory diagram of the coating head mechanism using the two-piece can outer peripheral surface coating method, Figure 4 is a plan view of the coating head mechanism, Figure 5 is an enlarged explanatory diagram of the gravure roll, and Figure 6 is a lal
Finished coating amount of each can and 80°C, 30 minutes (in hot water)
Figure 7 is a diagram showing the relationship between the number of peeled cans and the number of peeled cans, and Figure 7 is a diagram showing the relationship between the amount of finished coating film per can and the scratched area as determined by the vibration test. 10...2 B-S can, work 2...upper end,
14... Lower end portion, l6... Coater device, 22...
... Spindle mechanism, 26... Application head,
40...Coating roll, 42...Gravure roll, 44...Scraper roll.

Claims (2)

[Claims] (1) A two-piece can body exterior finishing coating method comprising applying an exterior finishing paint to a transfer roll, transferring the paint on the roll to the coating roll, and then applying the paint to the printed outer peripheral surface of the two-piece can body. , the transfer roll is a gravure roll having deep engravings on the entire circumferential portion corresponding to both the upper and lower ends of the can body, and shallow engravings on the entire circumferential portion corresponding to the center of the can body; A two-piece can body exterior finishing coating method characterized by applying a thick exterior finishing paint to both upper and lower ends of the outer peripheral surface of the two-piece can body and applying a thin exterior finishing paint to the center. (2) Two-piece can In a two-piece can with exterior finish coating provided on the outer peripheral surface of the can body with a printing layer and a transparent exterior finish coating layer thereon, the can body of the two-piece can has a coating on both its upper and lower ends. A two-piece can with exterior finish coating, characterized in that the exterior finish paint is thick and a coating film is formed in the center so that the exterior finish paint is thin.