JP2000070800A - Masking material and masking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an operator to relatively easily carry out the peeling of a masking material after painting by forming the masking material that is easily removable after masking of the non-painting portion of a material to be coated, of gelatin or material which is made into the gelatin by a hydrolyzing and heating treatment. SOLUTION: When an armor cover member A is subjected to electrostatic painting, the armor cover member A is first degreased by immersion of the armor cover member A into an alkaline tank, etc. A gelatin film as the masking tape C is then affixed to the non-painting portion B of the armor cover member A. The affixation is executed by bringing the affixation surface of the gelatin film into contact with the water, then affixing the film to prescribed points. The armor cover member A is subjected to electrostatic painting by spraying paint from plural painting guns g to the armor cover member A and is then subjected to drying and baking. The masking tape C curls to the direction where the tape shrinks from the circumference by allowing the affixed portions to remain near the center after baking and, therefore, the peeling of the masking tape C may be easily and efficiently executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a masking material for coating and a masking method, and more particularly, to a masking material which can be easily removed after masking a non-painted portion of an object to be coated, and a masking method using the same. .

[0002]

2. Description of the Related Art In a painting operation, when there is a part which is not desired to be painted, a method of sticking a masking material such as a masking tape to the part, painting the whole, and peeling off the masking tape after painting is an efficient method. It is a target. Then, it is necessary that the masking tape be easily peeled off after the coating, and after the tape is peeled off, the form should not be such that trouble occurs in the subsequent steps. For example, when performing electrostatic coating on a certain product, a masking tape is pasted on a predetermined portion of the product in advance, each product is suspended, and sequentially conveyed to an electrostatic coating line by a conveyor or the like. After coating automatically, evaporate the solvent using an infrared drying oven etc. to stabilize the finish of the coating.
Perform a baking process. After that, the masking tape is manually peeled off.However, if the applied tape is thin, it is difficult to peel it off.If it is thick, burrs are generated at the mark where the tape was peeled off, making it difficult to flatten it. There is a problem that the following may occur.

At present, various masking tapes are used, but all have their advantages and disadvantages, and improvements are required. For example, in the case of electrostatic coating or the like, a glass cloth tape (manufactured by 3M, trade name) made of glass fiber which has heat resistance and is impregnated with resin is often used. This is about 150 μm
Since it is thick and relatively thick, peeling after painting is easy. However, at the time of peeling after painting, the paint portion at the boundary between the tape-attached portion and the painted portion rises significantly (burrs are generated), which may hinder the subsequent assembly or use of the product. In other words, as shown in FIG.
Mask using 0μm thick glass cloth tape,
Then, paint about 80 μm thick from above. When the masking glass cloth tape is peeled off, the paint rises (in this case, the height is about 230 μm) after peeling off, as shown in FIG. In this state, FIG.
As shown in the figure, another metal member A 'painted in the same manner
When the non-painted portions are joined with screws or the like, the non-painted portions do not come into contact with each other, resulting in a void. When the final assembly is completed in the presence of such a part and the completed device is installed on a carpet, for example, the ground function does not work sufficiently. Breakage may occur, or impact may occur if the user touches it.

In order to solve such a situation, a thin polyimide (for example, Kapton, trade name) film having a thickness of about 30 μm is taken into consideration in consideration of the rise of paint at the boundary between the portion where the tape is attached and the painted portion. When used, the rising of the painted portion after peeling was small, but it was difficult to peel, and a tool for peeling was required.

The use of paper tape having an intermediate thickness of, for example, 80 μm was also considered, but the paper tape was damaged during the baking process after painting, and the paper tape was easily torn during the peeling. This was extremely time-consuming and was also unsuitable.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and it is relatively easy to peel off manually after coating without the need for special tools. Another object of the present invention is to provide a masking material and a masking method which do not cause rise of paint at the boundary between a peeled portion and a painted portion after peeling, and do not hinder subsequent assembly or use of the product.

[0007]

The above object is achieved by the invention described in the claims. That is, the characteristic constitution of the masking material of the present invention is that gelatin or a substance which becomes gelatin by a water / heat treatment is a main component. Gelatin is easy to process and can be formed into various shapes such as a film and a cylinder, and it is convenient because a coated material such as a metal material can be easily coated with water or the like. In addition, the state changes to a state where it can be easily peeled off by heating after coating, and the peeling operation can be performed efficiently. In addition, there is no rise of the paint at the boundary between the peeled portion and the painted portion after the peeling, and there is no trouble in assembling or using the product thereafter. Furthermore, gelatin is harmless because it is a kind of protein, and does not cause any harm to the operator throughout the coating process. As a result, according to the present invention, peeling after painting can be performed relatively easily by hand without requiring a special tool or the like, and paint rises at the boundary between the peeled portion and the painted portion after peeling. Thus, it was possible to provide a masking material that would not hinder subsequent product assembly or use. Incidentally, the masking material of the present invention may be composed of only gelatin, a substance that becomes gelatin by water-heating treatment, for example, collagen, and animal fibrous protein composed of collagen may be further used. Additives may be included. However, it is preferable that the masking material is made of only gelatin because it is homogeneous and acts stably on the heat treatment, but in the case of a substance which becomes gelatin by the addition of water and heat, it is preferable to the case where it is made of only gelatin. It is inexpensive in terms of cost. The gelatin may be not only animal but also vegetable.

It is preferable that the gelatin is in the form of a film and has a thickness of 50 to 300 μm. In this way, when the unpainted part of the painted object is a flat part, it is easy to stick, and if it is in the form of a film, it is relatively uniform in thickness. This is convenient because heating unevenness hardly occurs on the entire film upon heating, and the state changes to a state in which the film is easily and uniformly peeled from the entire periphery of the adhered film. When the thickness of the film is less than 50 μm, it is not preferable because it is difficult to peel off from the periphery of the sticking portion because it is thin. Similarly, if the thickness of the film exceeds 300 μm, the temperature of the film portion is less likely to be increased and the film portion is less likely to be peeled off during heating, which is not preferable. Incidentally, the thickness of the film is more preferably 80 to 150 μm.

[0009] The gelatin may be formed into a cylindrical shape. In this case, it is convenient to cover the non-painted portion of the painted object when the unpainted portion is three-dimensional, such as when a stud bolt is planted on the product surface. The shape of the tube can be various shapes and sizes according to the three-dimensional shape of the unpainted portion such as a cylinder, a square tube, a cap, a capsule, and other irregular shapes. The unpainted part of the painted object is not only a protruding part, but also a concave part, for example, when it is a hole part of a screw hole, a non-painted part can be easily formed by inserting a cylindrical masking material having a predetermined shape into the concave part. (A hole part) can be conveniently coated. In addition, if a flange having a diameter larger than that of the cylindrical portion is formed on the side wall of the cylindrical masking material, the masking material does not easily come off during transportation, and handling is convenient, and removal after heating is convenient. .

A feature of the masking method according to the present invention resides in that an unpainted portion of an object to be coated is covered with any of the masking materials described above. In this case, not only the masking work is easy but also the peeling work becomes easy,
Moreover, it does not cause any adverse effect on the operator, which is convenient. As a result, according to the present invention, peeling after painting can be performed relatively easily by hand without requiring a special tool or the like, and paint rises at the boundary between the peeled portion and the painted portion after peeling. Thus, it was possible to provide a masking method that would not hinder subsequent product assembly or use.

It is preferable that the coating is performed by immersing the surface of the masking material on the non-painted portion B by immersing the surface in water. This is because, when the masking material contains gelatin as a main component, the tackiness can be easily increased by coming into contact with water, the degree of tackiness can be controlled by the amount of contact with water, and the sticking operation becomes easy.

It is preferable that the masking material is formed into a tubular shape, and the tubular masking material is coated on an unpainted portion of an object to be coated. When the unpainted portion of the object to be coated is three-dimensional such as a convex portion or a concave portion, masking can be easily performed by coating according to the shape, which is convenient.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a masking method according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows, as an example, a case where electrostatic coating is performed on an exterior cover member which is an object to be coated. FIG. 1A shows a state where an exterior cover member A, which is an object to be coated, is suspended. The suspended exterior cover member A is degreased by immersing it in an acid or alkali bath. Next, as shown in FIG. 1B, a gelatin film having a thickness of about 100 μm is applied as a masking tape C to a non-painted portion B of the exterior cover member A which is not a painted portion. This sticking is performed by bringing the surface of the gelatin film to be stuck into water and then sticking it to a predetermined location since the gelatin film easily increases its tackiness by contact with water. In addition, it is convenient for handling if a surface opposite to the surface on which gelatin is adhered is subjected to a hydrophobic treatment.

As shown in FIG. 1C, electrostatic coating is performed by charging the outer cover member A to the positive pole and spraying paint from a plurality of coating guns g charged to the negative pole. . The coated outer cover member A is sequentially put into an infrared drying oven, dried at a predetermined temperature for a predetermined time, and dried. This drying and baking are performed at 80 ° C. for 5 minutes, and further for 10 minutes.
Preheating was performed at 0 ° C. × 5 minutes, and then heating was performed at 180 to 220 ° C. for about 20 minutes. The preheating is performed to allow the product to conform to the ambient temperature and to heat the entire product evenly. However, when the furnace volume is large and the furnace charge is large, it is not necessary to provide a preheating step.

After baking, as shown in FIG. 1 (d), the gelatin film C adhered to the non-painted portion B curls in the direction of shrinking from the periphery, leaving the adhered portion near the center. When the masking tape is in such a state, the peeling is easy and the peeling operation becomes extremely efficient.
In addition, the rise of the paint at the boundary between the painted portion and the peeled portion was not recognized at all, but rather the paint at the border portion was slightly thinner toward the non-painted portion. This was found to be due to the fact that the coating forming the boundary part had somewhat flowed to the unpainted part by the subsequent heating because the periphery of the gelatin film had already begun to curl during the preheating. Accordingly, the thickness of the gelatin film as the masking tape may be further reduced, and a film having a thickness of about 50 μm can be used. If the thickness is smaller than this, the curling force against the adhesion of the paint applied to the surface during heating is weak, and the curling is difficult. Also, when the thickness exceeds 300 μm, the heating of the metal-coated material proceeds rapidly, and only the gelatin film is not heated in advance.

Further, if the film is placed in a baking furnace and heated, the curl is left while leaving a portion to be partially adhered, and the same effect as described above can be obtained as long as it results in gelatin. It has been found. As such a substance,
For example, there are collagens that constitute animal proteins such as the skin of the sardines, which are adhered to non-painted parts by contacting with water, and then put into a baking furnace and heated. Even by such a method, the substance adhered after baking was curled, and peeling was extremely easy, and no burr was observed at the boundary between the paint part and the peeled part.

[Other Embodiments] (1) In the above-described embodiment, the unpainted portion of the product is a flat portion. However, as shown in FIG. In this case, the present invention can be effectively applied to the case where the surface of the stud bolt s is masked and other parts are painted. That is, FIG.
As shown in FIG. 2B, a capsule-shaped masking material C made of a thin film of gelatin is put on the stud bolt s on the work A on which the stud bolt s as shown in FIG. . In this case, the stud bolt s is a non-painted part. Then, as shown in FIG.
The paint is sprayed from a plurality of negatively charged paint guns g to perform electrostatic coating. After that, it is put into a drying and baking furnace and heated under the same conditions as in the above embodiment.
As shown in the figure, the bottom of the masking material C was slightly shrunk toward the stud bolt s. FIG. 3 shows a cross-sectional structure in which the capsule-shaped masking material C is removed from the stud bolt s. As described above, the painted portion p does not rise at the root of the stud bolt s, and is formed in a contracted state. Therefore, even when another member is screwed into the stud bolt s, it can be surely screwed to the root of the stud bolt s.

Conventionally, the stud bolts are masked by fitting a glass tube (for example, an Excel tube, trade name) made of a cylindrical glass fiber into the stud bolt before painting. However, since this masking material is made of glass fiber, there are problems in the working environment such as puncturing the worker's skin, causing itching and pain when manually inserting it into stud bolts or removing it after painting. there were. Further, after painting and baking, the glass tube cannot be easily removed from the stud bolt in many cases, and in many cases, it is necessary to use a tool such as radio pliers. Furthermore, after removing the glass tube, the boundary with the paint at the root of the stud bolt,
Burrs, which are the rising of the paint, occur, and when screwing another member to the stud bolt and tightening it, it is often not possible to tighten it to the root of the stud bolt.

However, the use of the masking material of the present invention is advantageous because such a problem does not occur at all.

(2) As shown in FIGS. 4, 5, and 6, the present invention can be effectively applied to a case where the object to be coated has a concave portion and the concave portion is to be masked for coating.
For example, as shown in FIG. 4, the object A to be coated is a nut n, and it is desired to mask an inner thread portion of the nut n. That is, a cylindrical masking material C made of a thin film of gelatin is inserted into an inner screw portion (unpainted portion B) of a nut before painting, and electrostatic painting is performed as it is. Also in this case, the masking material C could be easily peeled off after the coating, and did not cause any harm to the operator, and the same effect as in the above-described embodiment was obtained.

Furthermore, the object A to be coated is a bearing holder h having a shape as shown in FIG. 5, and the present invention can be applied to a case where it is desired to mask the internal thread portions of two holes formed in the holder h. In this case, a cap-shaped masking material C made of a thin film of gelatin is inserted into the inner screw portion (non-painted portion B) before painting, and electrostatic painting is performed thereon. Also in this case, after coating, the masking material C can be easily peeled off, and without causing any harm to the operator.
The same effect as in the above-described embodiment was obtained.

Further, as shown in FIG. 6, the workpiece A is a product having screw holes t of various diameters.
The present invention can be similarly applied to a case where the inner screw portion formed in the above-mentioned is to be masked. In this case, a multi-pin shaped masking material C having various diameters formed from gelatin is prepared,
Before painting, the pin is inserted up to the position of the outer diameter pin corresponding to the inner thread part (non-painted part B) of the screw hole t of various diameters, and electrostatic painting is performed from above. If a multi-stage pin-shaped masking material C having various diameters is prepared in advance as described above, a large number of screw holes having different diameters can be handled conveniently. Also in this case, the masking material C could be easily peeled off after the coating, and did not cause any harm to the operator, and the same effect as in the above-described embodiment was obtained. Of course, a pin-shaped masking material having an individual diameter as shown in FIG. 7 may be used. When a pin-shaped masking material with a flange as shown in FIGS. 6 and 7 is used, the masking material does not come off from the screw holes during handling before drying and baking, and the masking material is easily removed after drying and baking. It is preferable. When it is desired to mask the periphery of the screw hole t widely, it is sufficient to widen the flange portion greatly. In addition, although the shaft part of the masking material shown in FIGS. 6 and 7 has a solid shape instead of a cylindrical shape, the inside may be hollow.

(3) In the above embodiment, when the masking material is coated on the planar non-painted portion, an example is shown in which the film is adhered, but liquid gelatin is brush-coated on the non-painted portion. , Roller coating or the like. In that case,
It is preferable to make the thickness as uniform as possible so that the film starts to be uniformly separated from the surroundings by heating.

(4) In the above embodiment, the electrostatic coating method is described as an example of the coating method. However, the coating method is not limited to this, and can be applied to spray coating using a normal spray. In essence, the present invention can be applied to various coating methods in which a portion to be masked is masked in advance, then coated, heated after coating, dried and baked.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a masking method according to the present invention.

FIG. 2 is a perspective view illustrating a masking method according to another embodiment.

FIG. 3 is a front view showing a state after drying and baking by the masking method of FIG. 2;

FIG. 4 is a perspective view illustrating a masking method according to yet another embodiment.

FIG. 5 is a perspective view illustrating a masking method according to still another embodiment.

FIG. 6 is a perspective view illustrating a masking method according to yet another embodiment.

FIG. 7 is a perspective view of a masking material according to still another embodiment.

FIG. 8 is a diagram illustrating a masking method according to the related art.

[Explanation of symbols]

 A Painted object B Unpainted part C Masking material

Claims (6)

[Claims] 1. A coating masking material containing gelatin or a substance which becomes gelatin by a water / heat treatment as a main component. 2. The masking material according to claim 1, wherein said gelatin is in the form of a film and has a thickness of 50 to 300 μm. 3. The masking material according to claim 1, wherein said gelatin is formed into a cylindrical shape. 4. A coating masking method for coating an unpainted portion of an object to be coated with the masking material according to claim 1. 5. The masking method according to claim 4, wherein the coating is performed by immersing a surface of the masking material in water and attaching the masking material to the unpainted portion. 6. The masking method according to claim 4, wherein the masking material is formed into a tubular shape, and the tubular masking material is coated on an unpainted portion of the object to be coated.