This invention relates to a cleaning sheet intended for removing dust and other contaminating particles attached on the surface of a solid object such as a glass, plastic or metallic object.
With such particles attached on the surface of a product, not only is its external appearance adversely affected but also its functional characteristic may be affected. In view of such possibilities, it is a common practice to remove attached particles from the surface of not only a product as a whole but also each of its constituent members during its production or fabrication.
If there are dust particles and oily contaminating particles on the surface of a product such as a lens or a liquid crystal panel, its optical characteristics such as its index of refraction and optical transmissivity are degraded. Thus, contaminant particles are removed from such products. In the case of a product such as a ventilator fan or a filter, on the other hand, not only dust particles but also an oily contaminant material such as edible oil or mechanical oil is likely to become attached. In such a case, a mixture of dust particles and an oily substance is likely to drop from the product to pollute the work environment or clog a filter to adversely affect its performance characteristic. In the case of a product used outdoors such as an automobile, dust particles and oily substances can adversely affect the external appearance of the product.
Even during the production or fabrication process of these products, cullet and dust particles may become attached to surfaces of their constituent parts to cause damage or adversely affect the external appearance. In the case of a liquid crystal panel, cullet which is generated during its production process must be removed because it tends to damage the product surface. Even oily substances including resin materials and finger marks must be removed because they tend to adversely affect the performance characteristics such as the index of refraction and transmissivity. If paints are applied on the outer panels of an automobile with free flying particles attached thereon, they tend to become separated from the automobile body after the paint is dried such that the original panel surface comes to appear. Thus, removal of attached particles is an important process prior to the application of paints.
Conventionally, contaminant particles such as cullet and dust particles attached to the surface of a product or its parts during the production or fabrication process were removed by contacting the blade of a cutter knife tilted at a specified angle onto the surface to be cleaned and causing the knife to move along the target surface. The cleaning is also effected by using a mop or a brush comprising chemical fibers impregnated with a chemical agent. Use may also be made of a sponge or a piece of cloth, together with water or a cleanser. For removing oily stains such as resin and finger marks, solutions of acetone and alcohol may be used and the target surface is wiped manually.
By a method of using a cutter knife, however, the whole of the cutter knife must be uniformly contacted to the target surface of a solid object but the cutter knife does not remain in the same condition after a repeated use. It wears out, and it wears out unevenly. Thus, it is impossible to make the same contact all the time. In the presence of hard particles such as glass cullet, furthermore, they may be dragged by the cutter blade and end up by damaging the target surface. Moreover, a cutter knife can itself easily damage a soft surface, say, in the case of an external panel of an automobile or a plastic material. It also goes without saying that a cutter knife cannot remove oily objects such as resin and finger marks.
Removal of oily substances such as resins and finger marks is effected manually by using a solution of acetone and alcohol, but this must be effected as a separate process after dust particles are removed. This means that the cleaning process must be carried out in two stages, and this affects the work efficiency adversely. Because a manual work is involved, the quality control for maintaining a specified level of work quality is difficult. Even with a mop or a brush comprising chemical fibers as described above, removal of a mixture of dust particles and oily substances is difficult because the particles to be removed may pass between the fibers. Moreover, dust particles in narrow corners cannot be removed easily by such a mop or a brush. If the fibers themselves are rubbed against one another, furthermore, the particles once picked up by the fibers may be dropped back onto the target surface from which they were earlier picked up.
In the case of a ventilating fan or an automobile panel, water and a cleanser are commonly used but the use of water means that it can be effected only at a selected place, besides being cumbersome. In addition, the product must be dried after being washed with water, and this makes the process time-consuming.
It is therefore an object of this invention to provide a cleaning sheet capable of removing dust particles and stains from a target surface of a solid without damaging it.
A cleaning sheet embodying this invention, with which the above and other objects can be accomplished, may be characterized not only as comprising a foamed sheet and a polishing layer with abrading particles on its surface but also wherein a plurality of mutually disconnected indentations are formed through the polishing layer reaching the foamed sheet in a uniform point pattern including a plurality of mutually adjacent ginkgo-leaf shaped figures. Cullet and dust particles can thus be collected, as the cleaning sheet is pressed and rubbed against a target surface to be cleaned, through these indentations and into internal bubbles of the foamed sheet with openings on the upper surface. The arrangement of the indentations in a ginkgo-leaf pattern improves the efficiency of collecting cullet and dust particles.