NO117762B - - Google Patents

Description

Drying device.

The present invention relates to drying devices which should be able to dry wet and damp surfaces in a more satisfactory manner. The drying device according to the invention depends, when it comes to the way it works, on the interaction between a number of parts which together lead to an exceptionally good drying ability compared to previously known drying devices.

In order to achieve this effect, the pore sizes and the thickness of a hydrophobic layer must be adjusted in a specific way in order for the layer to interact satisfactorily with a hydrophilic sponge. It is from the U.S. patent 2,906,642, 2,906,643 and 3,080,688 known drying devices consisting of material combinations, but none have the characteristics of drying

the device according to the invention exhibits.

The drying device is essentially characterized in that it consists of a hydrophilic sponge provided on one surface with a compressible, compliant, open-pored, porous, hydrophobic layer, the thickness of which does not exceed 6.35 mm>of a flexible soft material with a pore size essentially prevents the hydrophilic sponge from coming into contact with the surface to be dried during normal compression of the drying device, but which conducts liquid from said surface to the hydrophilic sponge while the interface between the hydrophobic layer and the hydrophilic sponge part is water permeable .

A preferred embodiment is characterized by the pore size of the compressible hydrophobic material being between 16 and 48 pores/linear centimeter and the thickness of the layer being between 1.6 and 4 mm. ,

Another embodiment is characterized by the fact that the aforementioned layer of hydrophobic material consists of an essentially open network of interconnected fibers of a hydrophobic polyurethane resin and that the hydrophilic sponge consists of regenerated cellulose.

In order for the invention to be easier to understand, it will be explained in more detail in the following with reference to the drawing where: Fig. 1 is a perspective sketch of a drying device according to the present invention,

fig. 2 is an enlarged, fragmentary cross-section of the device in fig. 1 and

fig. 3 is a longitudinal section through an apparatus which can be used in the manufacture of the present device.

The present invention relates to a drying device consisting of a hydrophilic sponge body, to one surface of which is attached a layer no thicker than 6.35 n™&v a flexible, soft, compressible, elastic, three-dimensional, open-pored material of a hydrophobic , synthetic, organic, polymeric resin whose opposite surfaces are connected by essentially free passages, when said layer is under compression, and where the interface of said layer and said sponge body is water permeable. The passages connecting the opposite surfaces of the hydrophobic layers advantageously extend at least partially freely between the opposite surfaces of the hydrophobic layer in a direction perpendicular to the opposite surfaces. Furthermore, the hydrophobic layer advantageously has such a porosity and thickness that only a small part of the hydrophilic sponge during normal use reaches! the level of" the exposed surface of the hydrophobic layer, but advantageously not located at a distance exceeding 0.8 mm, when the drying device is used and under normal, manual compression.

The hydrophobic layer is advantageously a three-dimensional, substantially open network of interconnected strands of a hydrophobic core, but it can also be an open-pored foam provided that it fulfills the above-mentioned requirements. The hydrophilic sponge is advantageously a regenerated cellulose sponge, and the hydrophobic layer is advantageously formed of polyurethane and preferably polyurethanes. It should be noted that said network or open-pored foam can be equipped with a thin resin layer, e.g. with polyethylene, polyvinyl chloride or chlorosulphonated polyurethane The hydrophobic layer is advantageously attached to the co-structure with the layer to be partially embedded in said co-structure.

"It has been discovered that each drying device of the above-mentioned nature has far better properties compared to ordinary hydrophilic sponges of e.g. recalcitrant cellulose, and compared to other sponges made of e.g. hydrophobic synthetic resins, especially when they are used to wipe wet or damp surfaces. insignificant amount of water remaining on the dried surface. The water that remains is also in the form of extremely fine, small droplets, which evaporate very quickly without leaving streaks. It is assumed that the above-mentioned advantages arise from the fact that the hydrophobic, open-pored or straight network of the above-mentioned cores prevents a substantial, direct contact between the water-absorbing hydrophilic sponge and the surface to be dried. Said hydrophobic layer scrapes the water or moisture off the flat sonT bowl is dried using numerous hydrophobic surfaces, fine "threads" and edges that run across the surface, but which retain little water due to their hydrophobic nature. During drying, however, the hydrophilic sponge will come very close to the working surface of the hydrophobic layer, and the water will very easily come into contact with the 'hydrophilic sponge which is very strongly exposed to the water', which is then quickly absorbed. The drying float on the present device is thus always less' "saturated than the corresponding surface of the hydrophilic sponge. It is important to note that said hydrophobic layer should always be elastic, compressible

ibelt and flexible, and that the threads forming the layer should be soft and have great wear resistance, and that the layer must not have a greater thickness than that specified above, in order to achieve the above-mentioned properties. Furthermore, the hydrophobic layer should advantageously have a pore size of between 16 and 4P PPC, i.e. pores per linear centimeter.

In the attached drawing, fig. 1 and 2 a preferred embodiment of the present invention. The numeral 10 generally denotes the improved drying device, and consists of a back layer 11 and a front layer 12. Said layer 11 may be a piece or sheet of any desired configuration, and its thickness may vary from 3.17 rm to 7>5 rm or more. While said layer 11 is advantageously of regenerated cellulose sponge, preferably fiber-reinforced in a known manner and preferably produced by the viscose process, it can also consist of other highly hydrophilic sponge materials.

The front layer 12 consists of a flexible, soft, elastic, three-dimensional and generally open network of interconnected strands of a hydrophobic, synthetic, organic, polymeric resin, and is substantially free of membrane-like layers and should have a thickness, measured from the contact surface with layer 11 not exceeding 6.3510111 and preferably not exceeding 3>17 1.1111°g preferably at least 0.8 mm, and which is relaxed in its independent state. The polymeric resin forming layer 12 is advantageously a polyurethane resin, and preferably a polyether-polyurethane resin. The straight network of polyurethane can be produced in a known manner, e.g. by the method described in U.S. Patent No. 3.I7I.82O issued March 2, I965 to Volz et al. The hydrophobic layer advantageously has a porosity of between 16 and 48 PPC and preferably between 20 and 32 PPC, a density between 0.016

and 0.064 g/cm<3>, preferably between 0.024 and 0.040 g/cm 3 , and the voids advantageously constitute between Q0 and 99% of the volume, preferably between 95 and 98%. The porosity in the hydrophobic layer should preferably increase when the layer's thickness decreases. Have made a thickness of 0.8 mm, so

is optimum porosity approx. 40 PPC, while a thickness of 1.6 mm has an optimum porosity of 32 PPC and for a thickness of 3>17 111111 the optimum porosity is approx. 24 PPC.

The front layer 12 is attached to the back layer 11 so that the inter-phase is water permeable, and that the contact surface of the back layer 11 is in contact with the cavity in the front layer 12. The bonding is advantageously carried out by embedding the threads in the hydrophobic layer in the contact surface in the rear layer 11, so that a firm connection is obtained and

little obstruction to a flow of water through the front layer 12

to the back layer 11.

The drying device 10 can be produced by placing a layer of said hydrophobic resin over a layer of a viscous sponge mass of the desired thickness, after which sufficient pressure is applied to embed the hydrophobic layer in the viscous sponge mass, after which the viscose is coagulated, the cellulose is regenerated and the resulting composite material is cleaned, after which it is cut into the desired shape and size.

Fig. 3 shows a layer 13 of a viscous sponge mass which is continuously deposited at a uniform height on a continuously running endless belt 14. The composition of the sponge mass is well known, and may be as described in U.S. Patent No. 3,048,888 issued April 14, 1962 to A. Shockley et al, or U.S. Pat. patent no. 2,899,704 issued l8. August 1959 to F. Pekarek and can be continuously deposited on the conveyor belt 14, as described in U.S. Pat. patent No. 2,989,775 issued June 27, I96I to F. Pekarek or by any other suitable means. A layer 16 of the desired hydrophobic material is drawn from a roll or other supply source and passed around the periphery of and into contact with the surface of a supply roller 17 in contact with the advancing sponge mass 13. The roller 17 preferably has an elastomeric friction surface and should have the same peripheral speed as the forward speed of the belt 14* The roller 17 is vertically adjustable and positioned so as to obtain the desired embedment depth of the layer l6 in the sponge mass 13. The coated sponge mass 13 is then coagulated and the cellulose is regenerated in a commonly known manner, e.g. by electric resistance heating or by passing the mass through a hot salt solution. The regenerated cellulose was then washed, cleaned and bleached.

Said front layer 12, instead of being a straight network of the nature described in the above-mentioned Volz et al, patent, can be a layer of an open pore foam, preferably of polyurethane and with properties and dimensions as described above. The opposite surfaces of the open porous foam layer should not have membranes, and the layer is advantageously designed by cutting the foam along opposite surfaces on a block, so that the pores on said opposite surfaces are cut across and thereby fully exposed. The open-pored foam layer advantageously has a pore size of between 16 and 48 PPC, a thickness of between 3.97 mm and 1.59 ro™", and said thickness preferably varies in the same way as described in connection with the straight network. The foam. density should not. exceed 0.04 g/cm3 and should preferably lie between 0.016 and 0.025. g/cm3. The hydrophobic, open-pored layer is attached to the sponge layer in the same way as described above.

While preferred aspects of the present invention have been described and illustrated here, it is obvious that numerous modifications, omissions and additions can be made, without; one abandons the intention of the invention. One can e.g. use a polyester-polyurethane resin, or another polymeric resin that is soft, durable, flexible, . compressible., and elastic instead of said polyester-polyurethane resin. While said drying device has been illustrated in a flat rectangular shape with the hydrophobic open-pored layer only on one surface, one can further place hydrophobic layers on both sides of the hydrophilic sponge layer, except that one. can produce other shapes than what is shown in the drawing.

Claims (4)

1. Drying device, characterized in that it consists of a hydrophilic sponge provided on one surface with a compressible, compliant, open-pored, porous, hydrophobic layer whose thickness does not exceed 6.35 mm" of a flexible soft material with a pore size as in the essential thing prevents the hydrophilic sponge from coming into contact with the surface to be dried under normal compression of the drying device, but which conducts liquid from the said surface to the hydrophilic sponge while the separating surface between the hydrophobic layer and the hydrophilic sponge part is water-permeable. 2. Drying device as stated in claim 1, grade i-I is characterized by the pore size of the compressible hydrophobic material is between 16 and 48 pores/linear centimeter and that the thickness of the layer is between 1.6 and 4 mm* 3. Drying device as stated in claim 1 or 2, characterized in that the said layer of hydrophobic material consists of an essentially open network of interconnected fibers of a hydrophobic polyurethane resin and that the hydrophilic sponge consists of regenerated cellulose. 4. Drying device as stated in one or more of the preceding claims, characterized in that the said hydrophobic layer has cavities which make up between 90 and 99% of the layer's volume. 5'. Drying device as specified in one or more of the preceding claims, characterized in that the hydrophobic layer is partially embedded in the hydrophilic sponge.