JP2003523840A - Device for absorbing or collecting liquid - Google Patents

Abstract

  (57) [Summary] The present invention comprises a liquid reservoir and a porous membrane, the reservoir comprising an inlet, the reservoir being at least partially occupied by a porous bulk material, and the membrane must pass fluid through the inlet through the membrane Relates to a device for absorbing liquid, hermetically sealed in or around the reservoir, the membrane having an average pore size of 1 to 100 micrometers.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to a device for absorbing liquids, in particular spilled liquids. This application is for the control and absorption of spills of household or industrial origin (ie, "sponges"), the control and absorption of oil spills in the ocean, during medical emergencies and surgery. It includes blood control and absorption.

Sponge is an absorbent product that usually has an open porous structure. The open porous structure can be made from natural or synthetic materials. In general, the more open and porous the structure, the greater its ability to absorb and retain liquids. However, the more open and porous the structure, the smaller the capillary forces and therefore the liquid is easily drained from the sponge. On the other hand, if the structure is less porous, the capillary force will be greater, but the liquid will be absorbed relatively slowly.

US-A-5834385, published November 10, 1998, discloses a nonwoven hydrophobic membrane encapsulating an absorbent core, the entire product of which is used for oil spill elimination. Membrane pore size is not disclosed.

US-A-5678564, issued October 21, 1997, removes liquid by passing it through the membrane when it contacts the opposite side of the membrane and maintaining a vacuum in the receiving device for disposal. Disclosed is a system comprising a membrane that maintains and is capable of maintaining a reduced pressure on one side, such as

It is an object of the present invention to provide a device for absorbing or collecting liquid such as a sponge comprising a liquid reservoir and a porous membrane. To the liquid reservoir, the liquid to be absorbed must pass through the porous membrane which enhances the rate of absorption. Faster absorption rates than are possible with prior art methods and devices are possible.

In one aspect of the invention, the liquid reservoir has an open porous structure, and in another embodiment, the liquid reservoir comprises a void space.

SUMMARY OF THE INVENTION An object of the present invention is a membrane that is hermetically sealed to or around a container such that fluid passing through an inlet must pass across the membrane. Thus, the membrane is achieved by providing a membrane having an average pore size of 1 to 100 micrometers.

DETAILED DESCRIPTION OF THE INVENTION The device of the present invention is based on the principle of “closed dispersion”. By "closed dispersion", we here mean that the membrane is saturated with liquid and that the reduced pressure causes the bubble point (
If the bubble point pressure is not exceeded, it is meant that air is prevented from entering the system even under reduced pressure. The liquid can then be drawn through the membrane into the closed dispersion, for example by capillary action. Once the liquid goes into a closed dispersion, it is rapidly absorbed.

As used herein, the term “fluid” means a liquid or gas.

As used herein, the term “hermetically sealed” refers to a gas (when the membrane is saturated with a liquid, as long as the pressure differential separating the membranes does not exceed the bubble point pressure). This means that, in particular, air) cannot pass from the external environment to the inside of the container, nor from the inside of the container to the external environment. In particular, the membrane-to-container seal or the membrane-to-membrane seal prevents leakage of gas across the sealed area.

The membrane has an average pore size of no more than 100 micrometers, preferably no more than 50 micrometers, more preferably no more than 10 micrometers, and most preferably no more than 5 micrometers. It is also preferred that the membrane has a pore size of at least 1 micrometer, preferably at least 3 micrometers. Pore size distribution such that 95% of the pores have a size of no more than 100 micrometers, preferably no more than 50 micrometers, more preferably no more than 10 micrometers, and most preferably no more than 5 micrometers. Is more preferable.

The membrane has an average thickness of less than 1 mm, preferably less than 100 micrometers, more preferably less than 30 micrometers, and even more preferably the membrane is 1
It has an average thickness of no more than 0 micrometers, most preferably no more than 5 micrometers.

As used herein, the term “lipophilic” is less than 90 degrees,
It refers to materials having a reduced contact angle for transported oily liquids of preferably less than 70 degrees, more preferably less than 50 degrees, even more preferably less than 20 degrees, and most preferably less than 10 degrees.

As used herein, the term “hydrophilic” means less than 90 degrees,
It refers to a material having a reduced contact angle for distilled water of preferably less than 70 degrees, more preferably less than 50 degrees, even more preferably less than 20 degrees, and most preferably less than 10 degrees.

For convenience, the device for absorbing liquid is hereinafter referred to as a sponge. The term "sponge" is used generically herein and is not intended to be limiting.

[0016] In one aspect, the invention relates to sponges based on direct suction rather than being capillary. Where the liquid is essentially air (or other gas) (
Transported through areas that should not enter (at all, or at least in significant amounts). The driving force for the liquid flowing through such a sponge can be created by a liquid source (eg, spill) that is in fluid communication with the sponge either externally or internally. Direct suction is maintained by ensuring that substantially no air or gas enters the sponge. This means that the membrane should be substantially air impermeable up to a certain pressure, the bubble point pressure. Therefore, the sponge must have some liquid permeability. Greater liquid permeability provides lower flow resistance and is therefore preferred from this point of view.

However, for conventional porous liquid transport materials, which are materials that function based on a capillary transport mechanism (also referred to herein as “bulk material”), liquid transport is generally open. The interaction of pore size and permeability is controlled so that the highly permeable structures created are generally composed of relatively large pores. Their large pores provide a large permeable structure, however, their structure is
It has a very limited absorption height for each given combination of surface energies, i.e. given material and liquid type. Pore size can also affect liquid retention under normal use conditions.

In contrast to such conventional capillary driven mechanisms, these conventional limitations are overcome in the present invention. This is because, surprisingly, a material having a relatively low permeability (eg, a “membrane”) is a material having a relatively high permeability (eg, a “membrane”).
Bulk material ”) and the combination has been found to provide a significant synergistic effect.

In particular, large liquid-permeable materials with large pores filled with liquid are essentially impermeable to air up to a certain pressure, ie the bubble point pressure, but also relatively small liquid permeation. It has been found that when surrounded by a material that also has properties, the composite sponge has a large liquid permeability and at the same time a large bubble point pressure, thus allowing a very fast liquid transport.

[0020]   Bulk material   At least 10 important requirements for bulk area^-11m²,Preferably
10^-8m²More, more preferably 10^-7m²Over 10 and most preferably 10^-Fivem ² A small average flow resistance, as expressed by having a permeability k greater than
To have. To achieve such a large permeability for bulk materials
One important means is to utilize a material that provides a relatively large porosity.
Can be achieved. Of the material that makes up the porous material for the total volume of the porous material
It is commonly defined as the ratio of volumes and is quantified by commonly known density measurements.
Such porosity should be at least 50%, preferably at least 80%, and better.
It should preferably exceed at least 90%, or even 98% or 99%
It

In the extreme case of a bulk material consisting essentially of a single pore or void space, the porosity approaches or even reaches 100%. In this case, the liquid reservoir is defined by the wall region and the volume of the liquid reservoir is variable. Preferably, the volume changes either due to the flexible deformation of the wall area or the actuation of the piston.

The bulk material may have pores, which have a diameter of about 200 μm,
It is 500 μm, 1 mm or even 9 mm or more. Such pores may be smaller prior to fluid transfer so that the bulk material has a smaller volume and may expand just prior to or during contact with the liquid. Preferably, if such a pore is compressed or collapsed, it is at least 5, preferably 10
It should be expandable with a volume expansion coefficient of more than. Such expansion can be achieved with a material having a modulus above the external pressure, however, the external pressure must be less than the bubble point pressure. Large porosity can be achieved by numerous materials known per se in the art. For example, fibrous materials can easily achieve such porosity values. Non-limiting examples of such fibrous materials that may be included in the bulk region are, for example, from the polyolefin or polyester fibers used in the field of hygiene products, or in the automotive industry, or for the upholstery or HVAC industries. It is a high loft non-woven fabric made. Other examples include fiber webs made from cellulosic fibers.

Such porosity is also not intended to be any limitation, but is all well known from various industrial applications such as, for example, filtration technology, upholstery, hygiene, etc., polyurethane reticulated foam. It can be achieved by a porous open cell foam structure such as a body, a cellulose sponge, or an open cell foam (HIPE foam) made by a high internal phase emulsion polymerization process. Such porosity can be achieved by the wall region surrounding the void defining the bulk material as exemplified by the pipe. Alternatively, several small pipes can be bundled. Such porosity can further be achieved by "space holders" such as springs, spacers, particulate materials, corrugated structures and the like. The pore size or permeability of the bulk material can be uniform or non-uniform throughout the bulk material.

The large porosity of the bulk material need not be maintained throughout all stages of sponge manufacture and use, but voids in the bulk material may be present shortly before or during the intended use. Can be produced in. For example, a bellows-like structure, held together by suitable means, can be activated by the user, during its expansion the liquid penetrates through the port region into the expanding bulk material, whereby Fill the sponge completely or at least not enough to impede the flow of liquid. Alternatively, US-A-5563179 or US-A-5387207.
Open cell foam materials, such as those described in, have a tendency to collapse upon removal of water and the ability to re-expand upon rewetting. Therefore, such a foam will be relatively dry and thus in a thin (ie small volume) state upon contact with a source liquid that increases its volume so as to meet the requirements of void permeability. Only from the manufacturing site to the user.

The bulk material can have a variety of shapes or shapes. The bulk material can be cylindrical, ellipsoidal, sheet-shaped, striped, or any irregular shape. The bulk material can have a constant cross-sectional area and can have a constant or varying cross-sectional morphology such as rectangular, triangular, circular, elliptical or irregular.

The absolute size of the bulk material should be chosen to suit the geometric requirements of the intended application. In general, it will be desirable to have the minimum dimensions for the intended application. The advantage of the design according to the invention is that it allows a much smaller cross section than conventional materials. The size of the bulk material is determined by the permeability of the bulky material, which can be quite large due to the large pores possible. This is because bulk materials do not have to be designed under the contradictory requirements of large fluidity (ie large pores) and large vertical liquid transport (ie small pores). Such a large permeability allows for a much smaller cross section and thus a very different design.

The bulk material can be essentially non-deformable, ie it can maintain its shape, shape, volume under the normal conditions of the intended application. However, in many applications it will be desirable for the bulk material to allow a perfect sponge state that remains flexible and pliable. The bulk material may change its morphology, such as under the force or pressure of deformation during use, or under the influence of the fluid itself. Deformability or lack thereof may be achieved by the selection of material (s) as bulk material (such as fibrous members).

The limited separation of bulk materials may also include materials that can significantly change their properties upon wetting or even dissolve upon wetting. Thus, the bulk material may include an open cell foam material having relatively small pores made at least in part of a soluble material such as polyvinyl alcohol. The small porosity can be drawn into the liquid pair during the initial phase of liquid transport, and then rapidly dissolve to leave the large voids filled with liquid. Alternatively, such material may completely or partially fill the larger pores. For example, the bulk material may include soluble materials such as polyvinyl alcohol or polyvinyl acetate. Such materials may fill the voids or support the collapsed state of the voids before the sponge contacts the liquid. Upon contact with liquids such as oil or water, those materials may dissolve, thereby creating empty or swollen voids.

Membrane The term “membrane” as used herein is generally defined as a material or region that is permeable to a liquid, gas or suspension of particles in a liquid or gas. . For example, the membrane can include microporous regions that provide liquid permeability through the capillaries. Microporous hydrophobic membranes typically allow gas to permeate while driving pressures are generally "breakthrough" or "bridging".
Below a threshold pressure, called pressure, aqueous liquids are not transported through the membrane. In contrast, hydrophilic microporous membranes transport aqueous liquids. However, once wet, the gas (eg, air) will essentially not pass through the membrane if the driving pressure is below a threshold pressure, commonly referred to as the “bubble point pressure”. Hydrophilic, seamless films will typically allow water vapor to pass through, while gases will not be transported rapidly through the membrane. Similarly, the membrane can also be used for non-aqueous liquids such as oil. For example,
Most hydrophobic materials are lipophilic in nature. Therefore, the hydrophobic microporous membrane is
It is permeable to oil but not water and can be used to absorb and transport oil or to separate oil and water.

The membrane is often manufactured as a thin sheet, which can be used alone or in combination with a support layer (eg non-woven) or in a support element (eg spiral holder). Other forms of membranes include, but are not limited to, a thin layer of polymer coated directly onto another material, a corrugated sheet of bag.

Further known membranes may change their properties after activation or in response to a stimulus.
Activatable "or" switchable "membranes. This change in property can be permanent or reversible, depending on the particular application. For example, the hydrophobic microporous layer can be coated with a thin, soluble layer made of, for example, polyvinyl alcohol. Such a bilayer system would be impermeable to gases. However,
Once wet and the polyvinyl alcohol film dissolved, the system would be permeable to gases but still impermeable to liquids. Conversely, if a hydrophilic membrane is coated with such a soluble layer, it could be activated upon liquid contact so that liquids can pass but air cannot. .

Another useful membrane parameter is the permeability to thickness ratio, which is referred to as “membrane conductivity” in the context of the present invention. This means that for a given driving force, the amount of liquid that penetrates a material such as a membrane is, on the one hand, directly proportional to the permeability of the material, i.e. the higher the permeability the more liquid penetrates and Reflects the fact that it is inversely proportional to the thickness of the material. Thus, a material that has lesser transparency compared to the same material of reduced thickness indicates that thickness (when high speeds are considered desirable) can compensate for this lack of permeability. A typical k / d for a sponge according to the present invention is about 1 × 10 ^-9 to about 500 × 10 ^-9 m, preferably about 100 × 10 ^-9 to about 500 × 10 ^-9 m. Preferably k / d is at least 1 × 10 ⁻⁷ and more preferably at least 1 × 10 ⁻⁵ m.

For a porous membrane that is functional once wet (permeable to liquid, impermeable to air), at least the continuous layer of pores of the membrane must always be filled with liquid, gas or Not filled with air. Therefore, evaporation of liquid from the pores of the membrane is due to a decrease in the vapor pressure of the liquid, or an increase in the vapor pressure of the air, or to seal the sponge in an impermeable wrap such as a film of polyethylene. It has to be minimized, either by reason.

As described herein above, the devices of the present invention are particularly useful for cleaning domestic or industrial spills, eg from hard surfaces. The present invention may also have applications in the medical field, for example in absorbing blood or other body fluids.

It would be desirable to separate the oil from the water as completely as possible. In the most preferred embodiment of the invention, the device effectively separates oil from water, for example by selecting a suitable lipophilic and hydrophobic membrane.

Test Method: Bubble Point Pressure (Membrane) The following procedure is applied when it is desired to evaluate the bubble point pressure of the membrane.

First, the material of the membrane is connected to a length of tubing with a plastic funnel (catalog number 6256720, available from Fisher Scientific of Nidderau, Germany). The funnel and the tube are connected by an airtight path. Sealing is paraffin M (catalog number 61)
780002 (available from Fisher Scientific, Nidderao, Germany). Circular pieces of membrane material slightly larger than the open area of the funnel are sealed to the funnel in an air tight manner. The ceiling is, for example,
Made with a suitable adhesive such as Pattex from Henkel KGA, Germany. The lower end of the tube remains open, ie it is not covered by the membrane material. The tube should be of sufficient length, ie 10
Up to m lengths may be required.

If the test material is extremely thin or fragile, it may be separated by a very open support structure (eg, a layer of open pore nonwoven material) prior to connecting it to the funnel and tube. May be appropriate.

If the test sample is not of sufficient size, the funnel will be smaller (
For example, Catalog # 6 from Fisher Scientific of Nidderao
2561602). If the test sample is too large in size, the swatches can be cut to fit a funnel.

The test liquid may be the liquid to be transported (ie oil or grease), but for ease of comparison, the test liquid is of the Darmstadt, Germany under catalog number 1.08603. It should be a 0.03% TRITON X-100 solution of distilled or deionized water such as that available from MERCK KGaA, resulting in a surface tension of 33 mN / m. The portion of the funnel with the membrane is removed from the liquid, leaving the lower (open) end of the funnel in the liquid of the container. Although not required, in some cases (if appropriate) the funnel with the membrane material should remain leveled.

While continuing to slowly lift the membrane over the container, the height is monitored and if air bubbles begin to enter the interior of the funnel through the material (optionally assist with appropriate light). ) Carefully observed through the funnel or through the membrane itself. At this point, the height above the container is registered as being the bubble point height.

From this height H, the bubble point pressure BPP is calculated as BPP = ρ · g · H, where the liquid density is ρ and the gravitational constant is g (g = approximately 9.81 m / s ² ).
Is.

Especially for bubble point pressures above about 50 kPa, another quantification method such as is commonly used for assessing bubble point pressure for membranes used in filtration systems may be used. There, when the membrane separates a chamber filled with two liquids when the membrane is set up under increased gas pressure (such as air pressure), the first bubble "breaks through". The points are registered.

Pore Size Quantification Optical quantification of pore size is particularly used for thin layer porous systems by using standard image analysis procedures known to those skilled in the art.

The principle of the method consists of the following steps. 1) A thin layer of sample material is prepared either by slicing a thick sample into a thinner sheet or using it directly if the sample itself is thin. The term "thin" refers to achieving a sample thickness that is small enough to allow a clear cross-sectional image to be obtained under the microscope. Typical sample thickness is less than 200 μm. 2) Microscopic images are obtained by video microscopy with appropriate magnification. Best results are obtained if about 10 to 100 pores are visible on the image. The image is then a typical IBM
Bioscan Corp. running under Windows 95 on a compatible PC. Digitized by a standard image analysis package such as OPTIMAS. A frame grabber with sufficient pixel resolution (preferably at least 1024 x 1024 pixels) should be used for good results. 3) The image is converted to a binary image using the appropriate threshold levels such that the pores visible on the image are marked as white with a region of interest and the rest remain black. An automatic threshold setting procedure such as that available under OPTIMAS may be used. 4) The area of each pore (target) is quantified. OP
TIMAS provides a fully automatic quantification process of area. 5) The equivalent radius for each pore is determined by the circle that would have the same area as the pore. If A is the area of the pore, then the equivalent radius is r = (A
/ Π) ^1/2 . The mean pore size can then be determined from the pore size distribution using standard statistical formulas. For materials that do not have a very non-uniform pore size, it is recommended to use at least 3 samples for quantification.

Model number CFP-1200AEXI, Ithaca, NY, USA, as described in the 2/97 Careful User Manual.
0-13 as provided by Porous Materials, Inc. of a).
Any commercially available test equipment such as a capillary flow porometer having a pressure range of 80 kPa (0-200 psi) can also be used to quantify bubble point pressure, pore size and pore size distribution.

Thickness Determination Wet sample thicknesses were 1 and 1/8 ″ (approximately 2.86 cm) unless otherwise desired.
A conventional thickness gauge (such as that provided by AMES, Waltham, MA, USA) having a pressure foot diameter of 0.2 psi and exerting a pressure of 0.2 psi (about 1.4 kPa) on the sample. It is measured under the desired compression pressure at which the experiment is carried out by using (after a stabilization time of 30 seconds if necessary).

[0048]   Permeability and conductivity quantification   Permeability and conductivity are conveniently measured on commercially available test equipment.

For example, the device is commercially available as a permeameter such as that provided by Porous Materials Inc of Ithaca, NY under the name PMI Liquid Permeameter. This device contains two stainless steel frits as a porous screen,
It is also described in detail in the booklet. The device consists of a sample cell, an inlet container, an outlet container, and a drainage container and respective filling and draining valves and connections, an electronic balance, and a computerized monitor unit and valve control unit. For a detailed description of a suitable test method using this device, see the applicant's co-pending application PCT / US filed June 29, 1998.
/ 98/13497 (Docket Number CM1841FQ).

Example The sponge comprises a bulk material of polyurethane completely surrounded by a polyamide membrane. The membrane is sealed to itself at both ends of the sponge as well as along the length of the sponge so that all fluid entering or exiting the sponge must pass through the membrane. The membrane has an average pore size of 20 micrometers, an open area of 14%, a thickness of 55 micrometers, number 03
-20/14 Sephard (S of Ruschlikon, Switzerland)
efar) Inc. Manufactured by. Bulk material is 100mm long, 90m
It has a width of m and a depth of 5 mm, has 10 pores per inch, and is Kurede in Statallendorf, Germany.
manufactured by ta).

─────────────────────────────────────────────────── ─── Continued front page    (31) Priority claim number US9813521 (32) Priority date June 29, 1998 (June 29, 1998) (33) Priority claiming countries United States (US) (31) Priority claim number US9813523 (32) Priority date June 29, 1998 (June 29, 1998) (33) Priority claiming countries United States (US) (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, SD, SL, SZ, UG, ZW), E A (AM, AZ, BY, KG, KZ, MD, RU, TJ , TM), AE, AL, AM, AT, AU, AZ, BA , BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD, G E, GH, GM, HR, HU, ID, IL, IN, IS , JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, M N, MW, MX, NO, NZ, PL, PT, RO, RU , SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, Z A, ZW (72) Inventor Aernsperger, Bruno, Johannes             Federal Republic of Germany, day-65,936 francs             Kuhult, Westerbach Strasse             89 (72) Inventor Schmid, Matthias             Federal Republic of Germany Day 65510 Idsi             Uttain, Altkoenig Bake 3 (72) Inventor Glue Ann Bucher, Dana, Paul             45014, Ohio, United States             Airfield, Harrogate Hill Leh             1867 (72) Inventor Schone, liner, butter             Federal Republic of Germany, Day 61462 Konig             Stein, Romberg Bake 15 (72) Inventor Unak, Andrew Julian             45215, Ohio, United States             Ioming, Hidden Valley Lane             450 F-term (reference) 4F100 AT00A BA02 DA01 DD32                       DJ01B GB16 GB66 JD14                       YY00B

Claims (11)

[Claims] 1. A device for absorbing liquid, comprising a liquid reservoir and a porous membrane, the container of which has an inlet and which is at least partially occupied by a porous bulk material, the membrane being A membrane is hermetically sealed to or around the reservoir so that fluid passing through the inlet must pass through the membrane
A device having an average pore size of from 1 to 100 micrometers. 2. The device of claim 1, wherein the membrane has an average pore size greater than 10 micrometers. 3. A device according to claim 1 or 2, wherein the membrane has a pore size distribution such that 95% of the pores have a size not exceeding 100 micrometers. 4. A device according to any one of claims 1 to 3, comprising an inner porous bulk material in an outer membrane, the membrane being hermetically sealed by the membrane to a membrane seal. 5. The bulk material is replaced by the void space and the porous membrane is
The device of claim 1 having an average pore size of 0 to 100 micrometers. 6. The device of claim 5, wherein the liquid reservoir is defined by the wall region and the volume of the liquid reservoir is variable. 7. The device of claim 6, wherein the volume of the liquid reservoir changes due to the flexible deformation of the wall region. 8. The device according to claim 7, wherein the volume of the liquid reservoir is changed by the action of the piston. 9. A membrane according to claim 1, wherein the membrane has a bubble point pressure of at least 1 kPa when measured at ambient temperature and pressure using 0.03% distilled aqueous solution of Triton X-100 as the standard test liquid. The device according to item 1. 10. The device of claim 9, wherein the membrane has a bubble point pressure of 8 kPa to 50 kPa. 11. The device according to claim 1, wherein the membrane is a woven mesh or an apertured film.