JPH0221301B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a masking for painting that prevents paint from entering holes provided in an object to be painted, such as an automobile body.

Conventionally, for example, after applying anti-rust treatment and base coating to the entire surface of an automobile body in which pressed panels are welded and assembled, an undercoat paint is applied to the underside of the floor panel of the vehicle body for the purpose of soundproofing and rust prevention. It's being painted.

In this case, the floor panel has drainage holes and screw holes for attaching parts, and when applying the undercoat paint, the paint may enter through these holes and stain the interior of the car body, or the threaded parts of the screw holes may get dirty. In order to prevent the paint from adhering, a masking made of adhesive tape made of synthetic resin that is larger than these holes is used and is placed on the bottom surface of the floor panel to cover the holes, as known from Japanese Utility Model Publication No. 57-23474. The masking is applied so as to close the mask to prevent paint from entering, and the masking is naturally removed by melting or heat shrinkage in the baking drying oven after painting, making it possible to omit the work of removing the masking. It is something. However, in this case, since a relatively large amount (3 mm to 5 mm) is required for attaching the masking to the hole in the floor panel, the area around the hole in the floor panel must be painted to cover the amount of attachment. There are inconveniences such as a portion not being masked remaining and positioning of the masking being difficult when pasting. The object of the present invention is to provide a masking for painting that eliminates such inconveniences, and the masking body is shaped like a flange cup that fits into the hole of the object to be painted, and the masking body is formed in a baking drying oven. It is characterized by being formed so that it can be contracted and deformed by heating.

Embodiments of the present invention will be described below with reference to the drawings.
Referring to FIGS. 1 and 2, 1 indicates an object to be coated such as a floor panel of an automobile body;
A masking body 3 is fitted into a plurality of holes 2, such as water drain holes provided in the holder and screw holes for attaching parts, to prevent paint from entering these holes 2.

The masking body 3 is formed in the shape of a flange cup consisting of a cup part 3a and a flange part 3b on the open end side.The part of the cup part 3a near the flange part 3b is made slightly larger than the hole 2 The masking body 3 is fitted into the hole 2 until the flange 3b comes into contact with the painted surface of the object 1, and the cup 3a is inserted into the hole 2.
The masking body 3 is attached to the object 1 by the frictional force between the masking body 3 and the hole 2.

The width of the flange 3b was set to about 1 mm because the size of the flange 3b was sufficient to prevent the masking body 3 from coming off when the masking body 3 was fitted into the hole 2.

Further, the masking main body 3 is formed to be contracted and deformed by heating in a baking drying oven. In this case, the main body 3 may be formed of a heat-shrinkable synthetic resin, but high-impact styrene may be used. The masking body 3 may be drawn by press molding, vacuum molding, etc. using a thermoplastic synthetic resin film of 0.2 mm to 2 mm thick such as polystyrene, hard vinyl chloride, polypropylene, polyethylene, etc. In this case, When the masking body 3 is heated in the furnace, it becomes soft, and is contracted and deformed by the internal stress during molding so as to return to the shape before molding. To explain this in more detail, drawing forming such as press molding or vacuum forming is performed by heating the thermoplastic synthetic resin film to a temperature above the softening point and below the melting point, and then rapidly cooling it. According to , the masking body 3 is hardened with internal stress remaining in the circumferential side of the cup portion 3a due to the stretching in the generatrix direction, and when the masking body 3 is heated in the furnace. Due to the internal stress, it begins to shrink and deform in an attempt to return to its pre-molding shape, that is, a flat shape.

In this case, as the temperature of the masking body 3 gradually rises, shrinkage and deformation starts from the portion with the largest internal stress, so the peripheral side of the cup portion 3a of the masking body 3 contracts in the direction of the flange 3b. It deforms and finally becomes flat and falls off naturally from the object 1 to be coated.

The temperature at which shrinkage deformation begins varies depending on the material and the speed of temperature rise, but is approximately 50°C to 80°C, and the temperature at which shrinkage deformation ends is approximately 80°C to 110°C.

In addition, if a material is used in which the difference between the temperature at which shrinkage deformation begins and the melting temperature is the same, or if it is heated rapidly, the material will begin to melt before it shrinks and deforms due to internal stress, causing the masking body to melt. 3 loses its shape and melts while maintaining its shape, and adheres to the periphery of the hole 2, but this hardly causes any problems at the rate of temperature increase in a normal baking drying oven.

Furthermore, when the thermoplastic synthetic resins are arranged in order of suitability, high impact styrene is the most suitable, followed by polystyrene, hard vinyl chloride, polypropylene, and polyethylene, and in the case of the same materials,
A biaxially stretched film has a larger amount of heat shrinkage than an unstretched film, and is therefore more suitable.

Further, as shown in FIG. 3, after a plurality of cup portions 3a are simultaneously drawn and formed at appropriate intervals on a thermoplastic synthetic resin film, the cup portions 3a are
The masking body 3 may be formed by removing the periphery of the masking body 3 while leaving the flange portion 3b.

(Test example) After applying polyester anti-corrosion paint to the entire surface of the car body, in which pressed panels were welded and assembled, using a powder coating method, a 25 mm diameter water bottle was applied to the floor panel of the car body. Biaxially stretched high-impact styrene film was formed by vacuum forming into a total of 25 holes: 10 punch holes, 9 screw holes with a diameter of 10 mm for mounting parts, and 6 through holes for wires or pipes with a diameter of 8 mm. masking,
After fitting the floor panel from the bottom surface and spraying a melamine-based undercoat paint on the bottom surface of the panel, it was baked and dried for 10 minutes in a tunnel type drying oven heated with hot air at 170℃. The masking spontaneously fell off the panel.

As shown in FIGS. 4 and 5, when the cup portion 3a of the masking body 3 is shaped with a plurality of folds extending in the direction of its generatrix to make the cup portion 3a easily elastically deformable, When fitting the masking body 3 into the hole 2 of the object 1, the hole 2 and
This is advantageous in stabilizing the attachment force against manufacturing errors of the masking 3.

Further, by providing a convex portion on the top surface of the cup portion 3a, when a plurality of maskings 3 are overlapped and fitted successively using a jig or the like, the cup portions 3a of these maskings 3 are in close contact with each other. It is convenient because it can prevent this.

As described above, according to the present invention, the masking body is formed in the shape of a flanged cup that fits into the hole of the object to be coated, and is contracted and deformed by heating in the baking drying oven. Not only can the positioning of the main body be easily and accurately performed, but the unpainted area of the masking main body is relatively small, and the masking main body naturally falls off in the furnace, so that the masking removal work can be omitted. The overall effect is that the coating can be performed well and with high productivity.

[Brief explanation of drawings]

Fig. 1 is a front cutaway half-section view of a masking body according to an embodiment of the present invention, Fig. 2 is a cutaway front view of its usage state, and Fig. 3 is a perspective view showing a state in which a plurality of cup portions are drawn and formed at the same time. FIG. 4 is a half-cut front view showing a modification of the masking body, and FIG. 5 is a plan view thereof. 1... object to be painted, 2... hole, 3... masking body.

Claims (1)

[Scope of Claims] 1. A masking that prevents paint from entering a hole provided in an object to be painted, the masking body being in the shape of a flanged cup that is fitted into the hole and placed in a baking drying oven. A masking for painting, characterized in that it is formed to shrink and deform when heated. 2. The painting masking according to claim 1, wherein the masking body is formed by drawing and molding a thermoplastic synthetic resin. 3. The painting masking according to claim 1 or 2, wherein a plurality of folds extending in the generatrix direction are formed on the circumferential surface of the cup portion of the masking body.