JPH0536532Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a masking adhesive tape or sheet suitable for use in baking and painting automobile plastic bumpers and the like.

Conventionally, pressed steel plates have been used for the bumpers of automobiles, especially passenger cars, but now they are made of elastic polyurethane, elastic polypropylene, or other elastic plastic materials in order to reduce the weight of the car body and soften the impact in the event of a collision. has come to be used. If such plastic materials are made to be elastic, they will also elongate, especially when heated.

In addition, the surface of these elastic plastic bumpers is generally painted and decorated, but in order to have a good finish and a durable coating, it is necessary to
Baking paint is applied at 120°C for about 30 minutes, and the plastic bumper expands and expands during the baking process. The amount of thermal expansion is said to be about 1 to 2% in the case of elastic polypropylene, and about 1.5 times that in the case of elastic polyurethane. .

Furthermore, the above-mentioned plastic bumpers are not only painted in a single color, but also painted in two or three colors, or with lines of different colors. Masking adhesive tape or sheets are applied to mask the necessary areas.

Up until now, masking adhesive tapes for such uses have been made of washi paper or polyester as the tape base material.
It is not possible to expand to follow the thermal expansion of the plastic bumper, which is about 3%, resulting in inconveniences in painting, and an improvement has been desired.

In view of the amount of thermal expansion of the plastic bumper mentioned above, the present inventors considered that the base material for the masking tape should have a 50% modulus (the tensile stress required to elongate the sample by 50%) or a 100% modulus (the tensile stress required to elongate the sample by 50%). % tensile stress at the time of elongation) is not important, but the initial modulus at the beginning of elongation is important, and this led to the completion of the present invention.

As described above, the present invention uses vinyl chloride resin plasticized with a polyester plasticizer as the base material of the masking adhesive tape, and the initial modulus of the 10% modulus when measured at 23°C is 3.5 to 0.3. It has a low value of Kg/mm ² , and the adhesive layer formed on one side of the base material is a highly cohesive adhesive.

To explain an example below, the base material 1 of the masking adhesive tape is made of a soft vinyl chloride resin which is plasticized by adding the required amount of polyester plasticizer and has a 10% modulus of 3.5 to 0.3 Kg/ ^mm2 at 23°C. It is formed. 10% modulus is 3.5Kg/
If it exceeds mm ² , the adhesive tape will not have the necessary flexibility and elasticity, and will be difficult to adhere to curved or uneven surfaces, resulting in poor workability, and will also cause the plastic bumper to expand when baking the paint. Along with this, it becomes difficult to fully expand while following this,
It becomes impossible to obtain a good parting line. Also
If it is less than 0.3 Kg/mm ² , it is too flexible, has poor shape retention and dimensional stability, makes it difficult to obtain accurate and well-finished parting lines, and makes adhesive operations difficult. Of the above 10% modulus, about 2.3 to 0.6 Kg/mm ² is particularly preferable. In addition, the thickness of the base material can be formed as appropriate, but it is usually 0.07~
In many cases, about 0.1mm is sufficient.

Polyester plasticizers with relatively high molecular weights, such as Paraflex G-25 (trade name, Rohm and Haas, USA), Adekacizer
There are PN350, Adeka Sizer PN300 (trade name, Adeka Argus Co., Ltd.), and others. Vinyl chloride resins having various degrees of polymerization can be used, for example, about 800 to 1,500, and those of about 900 to 1,300 are particularly preferred. The amount of plasticizer required to add to the vinyl chloride resin to obtain the above modulus varies depending on the type and cannot be particularly limited, but for example, in the case of the above plasticizer,
Approximately 25 to 55% (weight%, the same applies hereinafter), preferably approximately
It is 32-42%. In addition to the plasticizer, stabilizers, colorants, and other compounding agents can be added to the vinyl chloride resin as necessary.

The adhesive layer 2 provided on the surface of the base material is preferably a relatively hard adhesive having high cohesion, heat resistance, and chemical resistance, such as a crosslinked rubber adhesive, an acrylic adhesive, and the like. The thickness of the adhesive layer can be formed as appropriate, but it is usually about 10 to 70μ, preferably
In many cases, a thickness of about 20 to 40μ is sufficient. The surface of the base material on which the pressure-sensitive adhesive layer is to be formed may be subjected to an appropriate undercoating treatment, if necessary. In addition to attaching a release paper to the surface of the adhesive layer, when stacking these adhesive sheets or winding the adhesive tape around a core, etc., the back of the base material can be attached with a release layer instead of the release paper. It may be processed into

The present invention has the above-mentioned structure, and since the 10% modulus of the base material of the masking adhesive tape is within the range of 3.5 to 0.3 Kg/ ^mm2 , it is flexible but does not stretch too much and has dimensional stability. It conforms well to the shape of the surface to be adhered to, allowing for easy application. Paint is applied to what has been masked in this way, and this is applied as shown above.
When baked at 120℃ for about 30 minutes, the plastic bumper expands thermally.
As this masking adhesive tape expands, it simultaneously stretches and follows this expansion.
It maintains neat parting lines forever, allowing you to finish the paint beautifully. In addition, when removing the masking adhesive tape after baking, the adhesive in the adhesive layer is a highly cohesive adhesive, so it can be removed cleanly from the surface of the plastic bumper even after heat treatment, and there will be no adhesive residue. You can get a beautiful painted surface without any problems.

This masking adhesive tape can be effectively used for painting plastic bumpers and other materials that expand and deform.

[Brief explanation of drawings]

The drawings show an example of the present invention, and Figure 1 is a slope view;
FIG. 2 is an enlarged sectional view taken along the - line in FIG. 1, FIG. 3 is a perspective view showing a modified example, and FIG. 4 is an enlarged sectional view taken along the - line in FIG. 1 is a base material, 2 is an adhesive layer, and 3 is a release paper.

Claims (1)

[Scope of utility model registration request] A masking adhesive tape for painting that has an adhesive layer on one side of a base material, and the base material is made of vinyl chloride resin plasticized with a polyester plasticizer and has a 10% modulus of 3.5 to 0.3 Kg/mm at 23°C. A masking adhesive tape or sheet for painting used for baking painting of a thermally expandable elastic material, in which the adhesive layer is made of a highly cohesive ^adhesive .