JP6153767B2 - Drying method for painted surfaces of pneumatic tires - Google Patents

Description

  The present invention relates to a method for drying a painted surface of a pneumatic tire in which a painted surface is dried after a water-based paint is applied to the tire surface of a pneumatic tire in which a color rubber portion other than black is formed on the tire surface.

  In order to describe the manufacturer name, product name, etc., in the pneumatic tire for vehicles, for example, a color rubber part other than black, for example, a white rubber part, for example, is formed on the surface of the sidewall part. May represent numbers, symbols, etc.

  By the way, pneumatic tires are often stacked and stored at the time of storage, and the tires often come into contact with each other during transportation. If it does so, the white rubber part may become dirty by the pneumatic tire printed on the surface of the side wall part by the white rubber part etc. by contact with other pneumatic tires. For this reason, in the tire manufacturing process, a water-based paint is applied to the surface of the white rubber part to form a protective film, and the protective film is removed by washing with water before the pneumatic tire is sold or mounted on the car. A technique for preventing the white rubber portion from being soiled by exposing the white rubber portion free from the soil is known.

  In the above technique, it is necessary to devise when applying a water-based paint on the surface of the white rubber part and then drying it. For example, when an aqueous paint is applied to the surface of the white rubber part and then naturally dried, the drying time and the manufacturing time become longer and the paint sagging occurs. On the other hand, when drying is performed by blowing warm air or the like in order to shorten the drying time, the thickness of the protective film and the like becomes nonuniform, and a portion where the thickness of the protective film is thick or thin is likely to occur. For this reason, the protection of the white rubber part may be insufficient in the thin part of the protective film, or the protective film may not be removed even by washing with the thick part of the protective film. .

  Regarding a drying method when a paint is applied to a tire surface, Patent Document 1 below describes a technique for generating a vortex of hot air on a painted surface on which a paint is applied.

JP-A-10-296173

  However, although the above technique is devised, it is still only hot air drying, so the thickness of the protective film after drying becomes non-uniform, and a part with a thick or thin protective film is generated. There was a case. Therefore, in the thick part of the protective film, it may take time for drying and may cause a problem that requires time for washing with water. Further, in the portion where the protective film is thin, the white rubber portion cannot be sufficiently protected, and the white rubber portion may be noticeable after the protective film is removed.

  The present invention has been made in view of the above circumstances, and the problem is that the drying time when the paint is applied to the tire surface is shortened and the film thickness of the protective film for the color rubber portion formed by the paint is reduced. Is to provide a method for drying a painted surface of a pneumatic tire that can achieve both the protective performance of the protective film and the cleaning performance when removed.

  In order to solve the above-mentioned problems, the present inventor examined hot air drying used in a drying method when applying paint to a conventional tire surface. In warm air drying, the surface of a paint hit by hot air is used. It turned out to be dry. As a result of further investigation, (1) tire sidewalls usually have a curved shape, but due to the weight of the paint, paint sagging occurs during drying, and the thickness of the protective film after drying is uneven. (2) In the method of drying from the surface of the paint, even if the paint on the surface is hardened, the inner layer part of the paint (the part in contact with the tire surface) is still fluid and the paint by its own weight The present inventor has found that the occurrence of sagging cannot be prevented. The present invention has been made based on the above discovery and has the following configuration.

  That is, the present invention is a method for drying a painted surface of a pneumatic tire, wherein the painted surface is dried after applying a water-based paint on the tire surface of a pneumatic tire in which a color rubber portion other than black is formed on the tire surface, The present invention relates to a method for drying a tire coating surface of a pneumatic tire, wherein the tire surface is heated to at least 40 ° C. or more in advance before the water-based paint is applied to the tire surface.

  According to the drying method, before the water-based paint is applied to the tire surface, by heating the tire surface to at least 40 ° C. or more in advance, immediately after the application of the water-based paint, the inner layer portion of the paint in contact with the tire surface is Hardens immediately due to heat on the tire surface. Then, heat is sequentially transmitted from the inner layer portion (the portion in contact with the tire surface) of the coating toward the surface layer of the coating, and finally the surface layer of the coating is cured. Thereby, the fluidity | liquidity of a coating material can be suppressed from immediately after coating and a coating dripping can be prevented. As a result, in the method for drying a painted surface of a pneumatic tire according to the present invention, after coating a water-based paint on the tire surface, the film thickness of the protective film can be secured from the initial stage, and the film thickness of the protective film after drying Can be controlled uniformly.

  Further, the present invention is a method for manufacturing a pneumatic tire in which a color rubber portion other than black is formed on the tire surface, and includes a drying step of drying a painted surface after applying a water-based paint on the tire surface, The present invention relates to a method for manufacturing a pneumatic tire, characterized in that the process is the drying method described above. In such a method for manufacturing a pneumatic tire, the thickness of the protective film of the color rubber portion is formed uniformly, so that the drying time is shortened.

  Furthermore, the present invention relates to a pneumatic tire manufactured by the manufacturing method described above, in which a color rubber portion other than black is formed on the tire surface. Such a pneumatic tire is a pneumatic tire in which a color rubber portion other than black is formed on the tire surface, and the protective film formed on the color rubber portion has a uniform thickness. Excellent detergency when removed by washing with water. Furthermore, the color rubber part is not soiled even after the protective film is removed.

  In the method for drying a tire painted surface of a pneumatic tire according to the present invention, a water-based paint is applied to the tire surface of a pneumatic tire in which a color rubber portion other than black is formed on the tire surface, and then the painted surface is dried.

  Below, the example of the pneumatic tire in which color rubber parts other than black were formed in the tire surface is shown. As such a pneumatic tire, a pair of bead portions, a sidewall portion extending outward in the tire radial direction from each of the bead portions, a tread portion connected to each outer peripheral end of the sidewall portion, and a pair of bead portions A radial tire provided with a carcass ply arranged so as to be bridged can be exemplified.

  The bead portion is provided with an annular bead core formed by rubber-covering a converging body such as a steel wire, and a bead filler positioned outside the bead core in the tire radial direction. The bead filler is generally made of a hard rubber having a triangular cross section extending in the tire radial direction.

  The carcass ply is wound up so as to sandwich the bead core and the bead filler, and its end is locked.

  An inner liner for maintaining air pressure is disposed inside the carcass ply. Further, a belt layer and a belt reinforcing layer are disposed outside the carcass ply of the tread portion, and a tread rubber is disposed outside the belt layer and the belt reinforcing layer. A rim protector that comes into contact with the rim flange when the vehicle is mounted is disposed outside the winding ply of the bead portion.

  Sidewall rubber is provided on the outside of the carcass ply of the sidewall portion, but in the pneumatic tire according to the present invention, a color rubber portion other than black, specifically, is provided on the tire surface of the sidewall portion in order to enhance fashionability. For example, a white rubber portion is disposed. The white rubber portion does not necessarily have to be disposed on the side wall portions on both sides, and may be disposed only on the side that becomes the vehicle outer side when the vehicle is mounted.

  The rubber composition for molding the white rubber portion is known, and a conventionally known rubber composition can be used without particular limitation in the present invention. In the white rubber part, carbon black is not used as a reinforcing material, and metal oxides such as alumina, magnesia, and silica are used instead.

  The method for drying a tire coating surface of a pneumatic tire according to the present invention is characterized in that the tire surface is heated to at least 40 ° C. or more in advance before the water-based paint is applied to the tire surface. By heating the tire surface to at least 40 ° C. or more in advance, immediately after coating, the inner layer portion of the paint contacting the tire surface is immediately cured by the heat of the tire surface without flowing. As a result, the thickness of the protective film can be ensured from the initial stage after the water-based paint is applied to the tire surface, and the thickness of the protective film after drying can be uniformly controlled.

  In order to more uniformly control the film thickness of the protective film after drying, when drying the tire coating surface of the pneumatic tire, before applying the water-based paint to the tire surface, the tire surface is set to at least 50 ° C. or more in advance. It is preferable to heat. On the other hand, in order to prevent the rubber from being deteriorated due to heating when the tire coated surface is dried, the heating of the tire surface is preferably 190 ° C. or less, and more preferably 140 ° C. or less.

  The method for heating the tire surface in advance is not particularly limited, but for example, known equipment capable of applying heat to the tire surface, such as heated steam, hot air dryer, steam, near infrared rays, hot plate, etc. It can be used.

  As the water-based paint, those known to those skilled in the art can be used, for example, those containing about 65 to 96% by weight of water and containing PVA (polyvinyl alcohol) or glycerin as a coating and stabilizer. Is done. Commercially available products can be suitably used as the water-based paint, and examples thereof include trade name W / B WSW PROTECTIVE COATING manufactured by APV.

  As a coating means for applying the water-based paint on the tire surface, for example, a method of spraying the water-based paint with a spray gun while finely pulverizing the water-based paint (for example, 10 μm to 500 μm) can be mentioned. In the present invention, if the tire surface is heated to at least 40 ° C. or more in advance during coating, the coating film (protective film) grows in the thickness direction while drying sequentially from the paint in contact with the tire surface immediately after coating. To go.

  In the method for manufacturing a pneumatic tire in which a color rubber portion other than black is formed on the tire surface according to the present invention, a pneumatic tire in which a protective film having a uniform film thickness is formed on the color rubber portion may be manufactured. it can. In the pneumatic tire manufactured by such a manufacturing method, since the thickness of the protective film formed on the color rubber part is uniformly formed, the color rubber part is not soiled even after the protective film is removed.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
Before applying a water-based paint (trade name W / B WSW PROTECTIVE COATING, manufactured by APV) on the tire surface of a pneumatic tire (tire size: (215 / 70R15)) in which a color rubber portion other than black is formed on the tire surface The pneumatic tire is put in a temperature-controllable storage in advance and heated until the tire surface reaches 40 ° C. Using such a pneumatic tire, a water-based paint is applied with the tire surface kept at 40 ° C. The tire surface was kept at 40 ° C. until it dried after painting.

Example 2-4, Comparative Examples 2 and 4
The tire coated surface of the pneumatic tire was dried by the same method as in Example 1 except that the temperature of the tire surface of the pneumatic tire was changed to the temperature shown in Table 1 before the aqueous paint was applied.

Comparative Example 1
Instead of the water-based paint, methanol-based paint (trade name PKB, manufactured by Nippon Shellac Co., Ltd.) was used, and the temperature of the tire surface of the pneumatic tire was changed to the temperature shown in Table 1 before applying the methanol-based paint. Except for this, the tire coated surface of the pneumatic tire was dried by the same method as in Example 1.

Comparative Example 3
Before applying the water-based paint, the tire surface of the pneumatic tire is not heated (the tire surface temperature is 20 ° C., which is room temperature), and instead the hot air of 50 ° C. is blown onto the tire surface to dry the tire paint surface. Except for the above, the tire painted surface of the pneumatic tire was dried by the same method as in Example 1.

  In addition, the evaluation method of each Example and a comparative example is shown below.

(Drying time of water-based paint (drying performance))
After the paint was applied to the tire surface, the time until the paint was dried and hardened was measured. Evaluation means index evaluation with the reciprocal of the drying time of Comparative Example 1 as 100, and the larger the index, the better the drying performance. The results are shown in Table 1.

(Uniformity of protective film thickness (uniform film thickness performance))
The average value of the film thickness of the protective film (coating film) formed on the white rubber portion deposited on the tire surface was measured. Specifically, the protective film after drying is peeled off from the tire surface, and the film cross section is magnified 200 times with a microscope (trade name (VHX-2000), manufactured by (Keyence)), and the film is analyzed by image analysis. The average thickness was measured. Evaluation means index evaluation with the average value of the film thickness of Comparative Example 1 being 100, and the larger the index, the better the film thickness uniformity performance. The results are shown in Table 1.

(Cleaning performance of protective film (membrane cleaning performance))
The protective film after drying was rubbed with a brush soaked in water, and the film cleaning performance was evaluated based on the number of rubs. In the evaluation, the reciprocal of the number of times of rubbing with the brush in Comparative Example 1 is regarded as an index, and the larger the index, the better the film cleaning performance. The results are shown in Table 1.

Claims (2)

A method for drying a painted surface of a pneumatic tire in which a painted surface is dried after a water-based paint is applied to a tire surface of a pneumatic tire in which a color rubber portion other than black is formed on the tire surface of the sidewall portion ,
A method for drying a tire coating surface of a pneumatic tire, wherein the tire surface is heated to at least 40 ° C. or more in advance before the water-based paint is applied to the tire surface. A method of manufacturing a pneumatic tire in which a color rubber portion other than black is formed on the tire surface of the sidewall portion ,
After a water-based paint is applied to the tire surface, it includes a drying process that dries the painted surface.
The method for producing a pneumatic tire according to claim 1, wherein the drying step is the drying method according to claim 1.