JP3445819B2 - Manufacturing method of two-piece cans and printing and coating equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to two-piece cans, relates particularly to a method of <br/> manufacturing two-piece can having a coating on the convex portion of the annular provided in the bottom surface, further, such a two-piece cans Related to printing and painting equipment.

[0002]

2. Description of the Related Art A two-piece can, as shown in FIG. 2 , is composed of a main body composed of a can body a and a bottom b, and a lid (not shown). As for 2-piece cans, there are 3-piece cans in which the can body, the can, and the bottom lid are separate bodies. In this specification, 2
The body of the piece can is simply called a two-piece can.

Recently, the speeding up of a two-piece can printing / painting line has been remarkably increased to 1500 to 1600 cans / min.

In the transport system in the printing and painting line, as shown in FIG. 6 , a two-piece can is erected on a running belt 72 and is transferred between front surface printing, back surface printing, a heating device and the like. The two-piece can is attached to the traveling belt 72 both when it is placed on the traveling belt 72 and when it is removed from the traveling belt 72.
Sliding with respect to 2. The traveling belt 72 is 2
A vacuum device capable of sucking the two-piece can onto the traveling belt 72 is provided within a range in which the piece can slides and moves.

The traveling belt 72 is divided into a plurality of sections. When the traveling belt 74 transfers the traveling belt 72, the two-piece can slides with respect to the traveling belt more frequently. Therefore, in order to make the transportation on the traveling belt smooth, the two-piece can must be slippery while standing.

For this reason, the can bottom of the two-piece can is provided with an annular protrusion c so that only the tip of the annular protrusion c contacts the surface of the running belt (FIG. 2 ). In other words, the contact area is made small so that the slip resistance becomes small.

However, due to the large slip resistance of the material of the two-piece can, for example, aluminum itself, it often falls on the running belt without slipping. Therefore, the ring-shaped convex portion c provided on the can bottom b is coated with a thermosetting coating in consideration of abrasion resistance to form a coating film d.

Further, as the line speed of the transfer system increases, the traveling belt 72 and the can bottom of the two-piece can slide against each other violently, so that the annular convex portion c of the can bottom in the transfer system wears hard. For this reason, the coating film d provided on the annular convex portion c is also scraped during the transportation, and the coating film is often lost to leave the metal surface. As a result, the slipperiness deteriorates, and during transportation, the can stops or falls due to friction, which may hinder the operation of the transportation line.

The inventors of the present invention have earnestly studied the disappearance of the coating film on the annular convex portion during transportation. As a result, when a thermosetting coating material is applied, the thickness of the coating film provided on the annular convex portion is reduced. It was found that there is a limit to this, and the present invention was achieved.

That is, in the current printing and painting line, even if the thermosetting paint is applied thickly on the annular convex portion of the bottom of the can and put in a heating oven to be heated and hardened, the heat is applied before the paint is hardened. As a result, the viscosity of the coating material is reduced, so that the coating material applied to the annular convex portion drips, and the coating film on the top surface of the convex portion of the core becomes thin. As a result, the wear resistance and lubricity of the bottom surface of the two-piece can become insufficient, which causes a hindrance to the operation of the above-mentioned transfer line.

Further, it is not preferable to apply the coating twice or three times in order to make the coating film thick on the annular convex portion on the bottom of the can because the process becomes complicated.

[0012]

SUMMARY OF THE INVENTION Therefore, the present invention has two features.
A thick cured coating film having excellent lubricity, hardness, and wear resistance can be easily formed on the bottom surface of a piece can by one coating. 2
A method of manufacturing a piece can is provided.

Furthermore, the present invention provides method for producing a good two-piece can of transportability when conveying placed on a high speed conveyor belt 及
And printing and painting equipment .

[0014]

The above objects can be achieved by the present invention described below. That is, in the method for manufacturing a two-piece can of the present invention, when the thermosetting paint is applied to the can body surface, the ultraviolet curable paint applied to the annular convex portion provided on the bottom surface is irradiated with ultraviolet rays. It is characterized in that the thermosetting coating material is cured in a heating oven after being cured by.

The two-piece can printing / coating device of the present invention comprises a can cylinder printer, a can cylinder paint coater, an annular convex paint coater provided on the can bottom, and a heating oven. An ultraviolet irradiation device is provided after the ring-shaped paint coating machine for the convex portion provided on the bottom, and the ultraviolet irradiation device arranges an ultraviolet lamp using a parallel light lamp house in parallel with the traveling direction and irradiates the can bottom with ultraviolet light. It is characterized by being able to do so.

The UV-curable coating material (hereinafter abbreviated as UV coating material) used for providing the UV-cured coating film on the annular convex portion provided on the bottom surface of the two-piece can is cured by UV irradiation and is abrasion-resistant. All UV paints with good properties and lubricity can be used. UV paints include radical polymerization type and photocationic polymerization type.

Specifically, in the radical polymerization type UV paint, the viscosity is basically reduced to a curable resin such as urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, unsaturated polyester, vinyl ether compound. Trimethylolpropane triacrylate, tripropylene glycol diacrylate, triethylene glycol diacrylate, pentaerythritol triacrylate, neobench glycol diacrylate, PO-modified glycerin triacrylate, phenoxyglycidyl ether acrylic acid adduct, alkyl acrylate An amide, a vinyl ether compound, etc. are added, and further, a photopolymerization initiator is added as an essential component. Depending on the case, a solvent, an extender pigment or a wax may be used.

In addition, in the cationic photopolymerization type UV paint,
Basically, a photopolymerization initiator is added to a curable resin such as a glycidyl type epoxide, an aliphatic epoxide, an epoxy cresol novolac resin, a polynuclear phenol / glycidyl ether derivative resin, an alicyclic epoxy resin, a hydantoin epoxy resin, a vinyl ether compound. Added as an essential ingredient. Depending on the case, a solvent, an extender pigment, a silicone resin, or a wax may be used. The polyol compound may be added to the curable resin in the presence of epoxy.

Further, a dual cure type UV paint utilizing two kinds of curing action by ultraviolet rays and heat can also be used by using a thermosetting resin together with the above UV paint, and as the thermosetting resin, an epoxy resin or a thermosetting resin can be used. Acrylic resin, thermosetting urethane resin, etc. can also be used.

In the embodiments of the present invention, the system for coating the bottom of an aluminum two-piece can is described. However, the material of the two-piece can is not limited to aluminum, and may be steel, laminated steel plate, or the like. . Further, it may be a physically or chemically treated material.

A specific example of the printing and painting line is shown in a flow chart in FIG. The printing and painting line includes a step of forming a printing / painting film on a two-piece can and is supplied with 2
Step 10 of forming a printing film using printing ink on the body surface of the piece can, step 20 of forming a thermosetting coating film on the body surface of the two-piece can using a thermosetting coating, and UV curing coating Step 30 of forming an ultraviolet curable coating film on the annular convex portion provided on the bottom surface of the two-piece can, step 40 of curing the ultraviolet curable coating film by ultraviolet irradiation, and heating of the print film and the thermosetting coating film. And the step 50 of solidifying are successively carried out, and thereafter the two-piece can is conveyed to the inner surface coating step and the drawing step.

A can cylinder printer (printing ink decorator) is used in the step 10 of forming a printing film on the cylinder surface of a two-piece can using the printing ink. In step 20 of forming a coating film of thermosetting paint on the body surface of a two-piece can, a can body paint coating machine (can body paint coating coater) is used. A can bottom paint coating machine (can bottom paint coating coater) is used in the step 30 of forming the coating film of the ultraviolet curable paint on the annular convex portion provided on the bottom surface of the two-piece can. Further, a heating oven is used in the step 50 of solidifying the printed film and the thermosetting coating by heating, and a mercury lamp is used in the step 40 of curing the ultraviolet curing type coating by ultraviolet irradiation.

In this specific example, an ultraviolet irradiation device was installed between a paint coating coater for a can bottom and a heating oven in a conventional two-piece can printing / painting line process.

FIG. 2 shows the shape of a two-piece can. The two-piece can has a can body a and a can bottom b integrally formed by drawing, and a lid (not shown) is attached to this.

An annular convex portion c is formed on the can bottom b at a height of 8 mm so that the friction between the can bottom b and the conveyer 72 is minimized when the can is raised on the conveyer 72 (FIG. 6 ). is doing.

FIG. 3 shows a state in which the ultraviolet curable coating film d is formed on the can bottom b of the two-piece can, that is, on the annular convex portion c provided on the bottom surface of the two-piece can. UV cured coating d
Has a thickness of 5-6 microns. According to UV curing,
The thickness of the coating film when the curable coating is applied is substantially the same as the thickness of the coating film after ultraviolet curing.

FIG. 4 shows a state where the ultraviolet curable coating material is applied to the annular convex portion c of the can bottom b of the two-piece can. The support rod 64 protruding from the pin chain 62 is held in a state of being covered with a two-piece can, and the pin chain 62 is so contacted that the can bottom b of the two-piece can is abutted against the coating surface of the coating roller 66.
Move like the arrow.

[0028] In the ultraviolet irradiation apparatus, using the traveling direction (arrow) parallel light lamp house 43 parallel up the UV lamp 42 of the pin chain 62 as shown in FIG. 5, results in a good effect.

If a large number of ultraviolet lamps are installed at right angles to the traveling direction, it will be wasteful and inappropriate.

As shown in the specific example of FIG. 1, it is preferable to install the ultraviolet irradiation device 40 in front of the heating oven 50. For example, if a can bottom paint coating coater is provided in front of the printing ink decorator, the apparatus becomes complicated and is not suitable. Further, when the can bottom paint coating coater 30 and the ultraviolet irradiation device 40 are provided after the heating oven 50, it is better to apply heat because the coating itself becomes strong by heating even after the ultraviolet paint is cured by ultraviolet rays. A reheat oven may be required.

[0031]

When a UV-curable coating material is applied on the bottom surface of a two-piece can, specifically, on the annular convex portion on the outer bottom surface and a cured coating film is formed by UV irradiation, the solvent-based coating material is used. Unlike this, the paint does not drip from the annular convex portion.

Therefore, it becomes possible to easily form a cured coating film having excellent lubricity, hardness and abrasion resistance and having a large film thickness on the bottom of a two-piece can by one-time coating.

[0033]

EXAMPLES Next, the formation of a coating film according to the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[Example 1] The following composition was put in a container and stirred continuously with a dispersion stirrer until it was sufficiently dispersed, and the viscosity was 91 seconds (Ford cup # 4, 25).
Thus, a UV-curable can bottom paint was obtained.

Aronix M-8030 (polyester acrylate manufactured by Toagosei Co., Ltd.) 30.0 parts Evecryl 220 (urethane acrylate manufactured by Dysel Ucybe) 20.0 parts TMPTA (trimethylol fluorotriacrylate) 10.0 parts TPGDA (tri 3. Propylene glycol diacrylate) 35.0 parts Ir-184 (photopolymerization initiator manufactured by Ciba-Geigy) 4.
0 part L-7001 (Nippon Unica Silicone resin)
5 parts polyethylene wax 1.0 part

[Example 2] The following composition was put in a container and stirred continuously with a dispersion stirrer until it was sufficiently dispersed, and the viscosity was 31 seconds (Ford cup # 4, 25).
Thus, a UV-curable can bottom paint was obtained.

UVR6110 (Alicyclic epoxy resin manufactured by Union Carbide) 50.0 parts UVR6105 (Alicyclic epoxy resin manufactured by Union Carbide) 25.0 parts TONE0301 (Polyol compound manufactured by Union Carbide) 15.0 Part DEG (diethylene glycol) 5.0 parts UVI6970 (photopolymerization initiator manufactured by Union Carbide) 4.0 parts L-7001 (silicone resin manufactured by Nippon Unica)
5 parts polyethylene wax 1.0 part

[Comparative Example] The following ingredients were put in a container and stirred with a dispersion stirrer until they were sufficiently dispersed, and the viscosity was 91 seconds (Ford Cup # 4, 25).
A thermosetting type can bottom paint was obtained.

Epicoat 1007 (Epoxy resin manufactured by Shell Chemical Co., Ltd.) 30.0 parts Bekkasite P-138 (Urea resin manufactured by Dainippon Ink and Chemicals Co., Ltd.) 10.0 parts Polyethylene wax 1.2 parts Butyl cellosolve 20.0 parts Methyl isobutyl ketone 20.0 parts xylene 20.0 parts

[0040] These paints, using a roll coater as shown in FIG. 4, is painted annular projection c in the can bottom b of aluminum two-piece can of 350ml capacity of FIG. In the case of UV paint, a mercury lamp 42 with an output of 120 W / cm is used, and 10 c is applied to the bottom surface of an aluminum two-piece can that is hung on a pin chain 62 at a speed of 10 m / min.
After irradiating with ultraviolet rays from a distance of m, it was heated for 60 seconds by a heating dryer at 200 ° C. In the case of thermosetting paint, 2
It was heated for 120 seconds with a heating dryer at 00 ° C.

Table 1 shows the test results of the bottom coating film of the coated two-piece can.

[0042]

[Table 1]

In Table 1, a dynamic friction coefficient measuring machine was used (load: 1000 g) to measure the dynamic friction coefficient. In addition, a Sutherland Lab Tester was used (load: 1000 g) for the measurement of wear resistance. The wear resistance was evaluated on a scale of 5, with 5 being the best and 1 being the worst.

As described above, when the thermosetting coating material was used, the abrasion resistance was poor because the film thickness of the coating film provided on the annular convex portion on the bottom of the can was small. On the other hand, it was shown that the wear resistance was improved by using the ultraviolet curable coating material.

[0045]

Since the present invention is constructed as described above, the following effects can be obtained.

(1) A coating film having excellent wear resistance can be formed on an annular convex portion provided on the bottom surface of a two-piece can.

(2) When a two-piece can is placed on a high-speed conveyor belt and conveyed, it can be prevented from falling down.

(3) Overcoating is not required to form a can bottom coating of a two-piece can.

[Brief description of drawings]

FIG. 1 is a flow chart showing the arrangement of a coating apparatus and the flow of a two-piece can according to the present invention.

FIG. 2 is a perspective view of a two-piece can with the can bottom up.

3 is a cross-sectional view illustrating a UV cured coating film provided on the convex portion of the annular in the can bottom of two-piece can of Fig.

FIG. 4 is a conceptual side view showing a roller for applying an ultraviolet curable coating film to an annular convex portion on the can bottom of a two-piece can and a transport pin chain.

FIG. 5 is a conceptual perspective view showing a mercury lamp for UV-curing a coating film applied to an annular convex portion on the can bottom of a two-piece can and a transport pin chain.

FIG. 6 is a conceptual side view showing a connection portion of a vacuum evacuation transfer conveyor that transfers a two-piece can in a two-piece can print coating line.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B05D 7/24 301 B05D 7/24 301T B41M 1/28 B41M 1/28 1/40 1/40 Z B65D 8/16 B65D 8 / 16 (72) Inventor Mutshiko Shiniki, 1500 Suganuma, Oyama-cho, Suna-gun, Shizuoka Mitsubishi Materials Corporation Aluminum Can Development Center (56) References JP-A-1-95832 (JP, A) JP-A-2-19248 ( JP, A) JPB 63-27990 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) B21D 51/26 B05D 1/00-7/26

Claims (2)

(57) [Claims] 1. A method for producing a two-piece can in which a thermosetting paint is applied to the can body surface, wherein an ultraviolet-curable paint applied to an annular convex portion provided on the bottom is cured by irradiation with ultraviolet rays and then heated. A method for producing a two-piece can, which comprises curing the thermosetting coating material with. 2. A two-piece can printing / painting device comprising a can body printer, a can body paint coating machine, an annular convex portion paint coating machine provided on the can bottom, and a heating oven. An ultraviolet irradiating device was provided after the annular paint coating machine for convex parts, and the ultraviolet irradiating device was arranged such that an ultraviolet lamp utilizing a parallel light lamp house was arranged in parallel with the traveling direction so that the can bottom could be irradiated with ultraviolet light. A printing and coating device for 2-piece cans, which is characterized in that