Automobile paint film-protective sheet

Abstract

An automobile paint film-protective sheet comprising a substrate having formed on one side thereof a rubber-based pressure-sensitive adhesive having a dynamic modulus of from 2×105 to 7×106 dyne / cm2 at 60° C.

Description

[0001]This is a continuation of application Ser. No. 07 / 900,293 filed Jun. 18, 1992 now abandoned.FIELD OF THE INVENTION[0002]The present invention relates to an automobile paint film-protective sheet which is hard to cause a paint film deformation and suitable for use in the surface protection of automotive bodies and other parts.BACKGROUND OF THE INVENTION[0003]An effective measure is desired to prevent automobile paint films from suffering damages, dulling, discoloration, and other defects due to various suspended or impinging matters such as dust particles and raindrops. Such paint film protection is necessary, for example, in the case of loading painted automobiles or automotive parts into trucks or ships and transporting these to remote places such as overseas.[0004]A method of covering painted automobiles or automotive parts with a 5-20 μm-thick coating comprising a wax has been known as a measure for such paint film protection. However, this method has had, for example, the ...

AI Technical Summary

Benefits of technology

[0010]According to the present invention, by using a rubber-based pressure-sensitive adhesive having a dynamic modulus of from 2×105 to 7×106 dyne / cm2 at 60° C., the paint film-protective sheet not only is hard to suffer a change in adhesion strength due to the good heat resistance of the pressure-sensitive adhesive layer even under temperature-rising conditions during outdoor transportation, etc., but also have excellent two basic performances of protective properties due to good adhesion and strippability and retain a good balance between the two basic performances over a long period of time. Further, by blending a silicone oil or an acrylic polymer having a molecular weight in the specific range with a rubber-based pressure-sensitive adhesive, the adhesion strength of the pressure-sensitive adhesive to paint films can be reduced and regulated in a proper range. Due to this and because of the good heat resistance of the rubber-based pressure-sensitive adhesive used, the adhesion strength of the protective sheet applied to painted automobiles or automotive parts is effectively prevented from increasing even when the protective sheet is exposed to temperature-rising conditions due to outdoor transportation or by other factors. As a result, adhesive remaining and paint film deformations such as gap formation, particularly at the edge parts of the protective sheet, can be avoided; such troubles and defects have been involved by the use of conventional protective sheets due to differences in expansion and contraction degree between the paint film and the protective sheet with changing temperature.

Problems solved by technology

However, this method has had, for example, the following various problems.

It is difficult to form a wax coating at a uniform thickness, so that uniform protection of the paint film cannot be obtained; wax coatings are prone to be fouled and have poor resistance to acid rain; part of the wax may penetrate into the paint film to cause discoloration or other defects; formation of a wax coating and removal thereof require much labor; and use of solvents and treatment of waste liquids are apt to lead to environmental problems.

The above surface-protective sheet, however, has been defective in that preparation of a radiation-curable pressure-sensitive adhesive used to form the pressure-sensitive adhesive layer requires a complicated and special technique.

In addition, the protective sheet has had other problems that the pressure-sensitive adhesive layer obtained shows poor adhesion strength and that the pressure-sensitive adhesive layer has poor heat resistance, probably because the adhesive layer has been made to have a lowered glass transition point to impart a particular performance required in paint film-protective sheets, i.e., preventing the deformation of the paint film.

Due to such a pressure-sensitive adhesive layer, application of the protective sheet to automobiles has had a problem that the adhesion strength of the sheet applied to an automobile increases with increasing temperature during outdoor transportation, etc., making stripping of the sheet difficult.

Thus, the proposed surface-protective sheet has been unsatisfactory in basic performance.

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