Coating implements with material supply – Material flows through porous tool
Reexamination Certificate
2002-08-20
2004-02-03
Huson, Gregory (Department: 3751)
Coating implements with material supply
Material flows through porous tool
C401S201000, C015S244100
Reexamination Certificate
active
06685376
ABSTRACT:
Translation of PCT/EP01/01954 as filed on Feb. 21, 2001.
BACKGROUND OF THE INVENTION
The invention relates to a method for the manufacture of a cleaning or application sponge, as well as to a cleaning or application device, which is equipped with a corresponding sponge or sponge body.
For the manufacture of cleaning and application sponges, such as are now more particularly used in the home, it is known to initially produce a relatively large block from polyurethane foam, which is parallelepipedic or cubic. The sponge is then worked from this foam block by cutting and/or punching. If in addition gripping depressions are to be made in the sponge or if its edges are to be beveled, the sponge must undergo a subsequent cutting process. The known manufacturing method is disadvantageous in a number of respects.
Firstly the method is very complicated and therefore costly as a result of the numerous method steps to be successively performed. In addition, the foam blocks are not normally produced by sponge manufacturers and are instead bought in from third parties, so that they must firstly be transported to the sponge manufacturer. In order to reduce the very large transportation volume, it is known to compress the foam blocks, but there is still a relatively large transportation volume for a small transportation weight, so that the transportation of the foam blocks is not economical. In addition, the sponge manufacturer must have a large storage space for the foam blocks and this leads to complicated storage.
On punching and/or cutting out the sponges and in particular during their finishing, there is a very considerable material loss or waste, which is neither economical nor good for the environment. The cutting, punching and milling processes only allow very limited shape configurations and in particular it is not or only with great difficulty possible to form undercuts or subject designs, e.g. animal or human representations.
A significant disadvantage of a sponge worked from a foam block is that the pores on the sponge edges are cut open, which is linked with a stability loss of the sponge in these areas. However, during practical use of the sponge, its edges and corner areas are more particularly needed for cleaning or application purposes, so that the use characteristics of the known sponge are inadequate in this respect.
For many applications it is appropriate and necessary to bond the sponge on at least one side with a coating. For this purpose a blank of the coating to be bonded is produced and said coating is then applied by a flame bonding process. However, this procedure is very labor intensive and also not completely safe.
On of the important disadvantages of the known sponges is the uniform pore or cell structure over the entire sponge volume. If a sponge is wetted and used for cleaning purposes, then the moisture is not only forced in the direction of the article to be cleaned or otherwise treated, but also flows onto the fingers holding the sponge and the hand surface of the use supporting the sponge. This consequently does not allow a targeted use of the cleaning liquid or the medium to be applied.
The problem of the invention is to provide a method for the manufacture of a cleaning or application sponge with which, even in the case of a complicated design, manufacture can take place in an inexpensive and environmentally compatible manner. In addition, a cleaning or application device with a corresponding sponge body is to be provided.
SUMMARY OF THE INVENTION
With regards to the method this problem is solved in that the sponge body is foamed or expanded in a mould essentially to the final shape or form of the sponge and on the outer surface of the sponge body during said foaming or expansion process and at least in partial areas thereof, but in particular on the complete outer surface, a strengthened or hardened outer skin is produced.
Thus, during the foaming process the sponge body acquires the desired shape, so that little or no subsequent finishing is necessary. Compared with known sponge manufacture the total number of method steps is significantly reduced, so that the sponge can also be inexpensively manufactured. The aforementioned problem relating to the transportation and storage of the foam blocks can be completely avoided with the method according to the invention. As, according to the invention, the sponge is shaped by the cavity of the mould and not by finishing involving material removal, the material losses can be kept very small.
The formation of the hardened outer skin on the outer surface of the sponge body can be obtained in that the method parameters, e.g. the mould temperature, cooling, foam density, foaming pressure, etc., which are controlled by the composition of the plastics material, are adjusted in such a way that on the outer surface of the sponge body is formed the closed, hardened plastics material skin. The hardened outer skin increases the stability of the sponge body and in the areas of the latter used for product application the outer skin is subsequently at least zonally opened or removed, which can e.g. take place by milling, cutting, grinding, peeling, sand blasting or partial dissolving.
Preferably the interior of the sponge body has a closed-cell structure, which can be zonally opened in a following method step. In this way it is possible to leave certain areas of the sponge body in closed cell form, so that these areas on the one hand have an increased stability and on the other it is ensured that the liquid present during use in the sponge body does not pass out at these areas. Preferably the closed-cell foam is only opened in these sponge body areas, which are used for product application, which permits a targeted escape of liquid or medium to be applied from the sponge body.
The opening of a closed-cell foam structure is known per se and can e.g. take place by mechanical bursting using pressure, known as crushing.
The areas of the sponge body, which remain unopened and consequently have a higher strength, can serve as gripping portions for the user. In particular, the sponge body areas to be used for the direct or indirect retention of the sponge body on gripping parts, handles, sticks, etc. can remain closed-pored.
During the foaming process in the mould use is generally made of parting agents, which in the case of the method according to the invention can be removed without additional measures by opening the closed-cell structure on the surface or the opening of the outer skin.
Not only raising the density of the foam material, but also by a suitable temperature control in the foaming moulds, can increase the edge strength of the sponge body. If the foaming reaction takes place in a closed mould e.g. thermally maintained at 30 to 60° C. and more plastics material than necessary is filled into the mould cavity, accompanied by compression or compacting this material cross links to a harder structure with the denser outer skin, which continuously passes into a cellular core. Through an appropriate choice of the temperature and the material mixture introduction into the mould cavity, in this way it is possible to obtain planned foam structures and surface structures with high edge strengths.
If, in the aforementioned manner, on the sponge body are to be formed more stable holding or gripping portions or sealed areas, in said sponge body portions the outer skin is not opened.
As a suitable sponge body material flexible polyurethane foam has proved highly satisfactory and its foam density can be between 25 and 80 kg/m
3
. It is in particular possible to use polyester-PUR foam.
According to a further development of the invention the foam body comprises several differently structured foam body portions. The foam body portions can be prefabricated and are then joined together by bonding or welding.
A preferred manufacturing possibility results from the fact that the mould cavity is subdivided by one or more partitions, particularly in the form of slides, into several chambers. A foam material can be filled into and reacted in eac
Coronet-Werke GmbH
Huynh Khoa D.
Vincent Paul
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