Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,... – Repair – replacement – or improvement
Reexamination Certificate
2001-03-15
2003-12-30
Swann, J. J. (Department: 3677)
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
Repair, replacement, or improvement
C405S036000, C524S590000, C528S060000, C528S061000
Reexamination Certificate
active
06669407
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polyurethane geotextile composite having improved water resistance. Additionally, the present invention relates to a process for forming a polyurethane geotextile composite having improved water resistance.
BACKGROUND OF THE INVENTION
In recent years, the management of natural resources has become important in many countries throughout the world. Efforts have been directed both toward the conservation of our resources and toward the elimination of pollution from our environment. Particular emphasis has been placed on waste leakage and water loss.
Losses in the distribution of water using unlined irrigation ditches are estimated at a minimum to be 25% and in some situations to be more than 50% depending upon the porosity of the ditch surface and the distance the water is being moved. In most rural areas, ditches are formed by excavating the soil to the desired depth and width. The water moves through the ditch in contact with the exposed natural surface. This can be sand, clay, rocks, etc. and, more commonly, mixtures thereof. The porosity will depend upon the proportions of the different components in the soil.
The loss of water in unlined irrigation ditches at one time was considered acceptable only because the supply of water exceeded demand. However, as civilization has developed and world population has increased, more water is required for both greater food production and for the marked by increasing in non-agriculture uses. In addition to greater domestic uses in sanitation, industry now employs large quantities of water in manufacturing and processing procedures.
This high level of consumption plus the very high cost of developing new water supplies has shifted attention to water conservation. Domestic appliances that use less water have been developed. Also, industry has installed recycling purification systems to reduce water consumption.
Although conservation efforts have reduced water consumption to a degree, water is still in relatively short supply, particularly in recent years with the severe droughts in the United States and other countries. Since the most cost effective conservation opportunities and readily accessible water supplies already have been developed, greater attention must be directed to improving the efficiency of water distribution systems.
Improvements in water distribution have been made. A limited number of ditches and canals have been lined with concrete and/or preformed concrete pipes. Concrete is durable and has a long life when properly used. However, concrete is expensive to place and finish and is damaged by unfavorable temperatures during curing. Also, concrete is subject to frost damage, cracking and heaving which results in leaks.
Processes for forming composite liners for canals and ditches and apparatus to perform such a processes are disclosed, for example, in U.S. Pat. Nos. 4,872,784; 4,955,759; 4,955,760; 5,049,006; 5,062,740; and 5,421,677.
However, the above-noted patents give almost no guidelines as to the solidifiable compositions which should be used. For example, U.S. Pat. No. 4,872,784 (at column 5, lines 55-60), U.S. Pat. No. 4,955,759 (at column 5, lines 58-63), U.S. Pat. No. 4,955,760 (at column 4, lines 55-60) and U.S. Pat. No. 5,062,740 (at column 4, lines 56-61) broadly suggest the use of a foamed polyurethane resin but no specific formulations are taught or suggested. U.S. Pat. No. 5,049,006 (at column 4, lines 26-32) and U.S. Pat. No. 5,145,282 (at column 5, line 64—column 6, line 2) broadly suggest the use of a thermosetting resin forming mixture such as a polyester or a polyurethane forming mixture, without describing any specific formulations.
U.S. Pat. No. 5,421,677 (“the '677 patent”) is directed to an improved process for forming a ditch liner. The '677 patent discloses the use of a mixture of one or more polyisocyanates, a polyol mixture, one or more fillers, and a catalyst. The mixture of the '677 patent is dispensed on a geotextile, thereby forming a liquid polyurethane soaked geotextile composite. The liquid polyurethane soaked geotextile composite is then placed over the surface of an area to be lined and allowed to cure, to form a polyurethane/geotextile composite. One drawback of the mixture taught by the '677 patent is that the filler in the mixture is often not completely dry and can absorb additional moisture from the atmosphere. Moisture is always present when the mixture is applied under relatively humid conditions. This water will react with the polyisocyanate and cause the mixture to foam. Foaming weakens the strength and impermeability of the composite.
Even when completely dry fillers are used in the mixture under non-humid conditions, the polyurethane geotextile composite, when stored under water (such as in a ditch or canal liner application), can absorb considerable amounts of water (i.e., 1-2%) which swells and weakens the liner.
For the foregoing reasons, it would be desirable to develop an improved polyurethane composition that does not foam, even when applied under humid conditions and is less sensitive when wet filler is used in the polyurethane composition. Additionally, it would be desirable to develop a polyurethane geotextile composite liner that has substantially lower water absorption.
SUMMARY OF THE INVENTION
The present invention relates to a polyurethane geotextile composite with improved water resistance useful as a liner for a ditch or canal in which the polyurethane used is a reaction product of a mixture comprising:
a) a liquid polyisocyanate having an isocyanate content of at least 10% by weight,
b) an isocyanate-reactive component comprising:
(i) 20 to 90% by weight, based on total weight of b), of castor oil having an OH number of from about 160 to about 170, a viscosity of from about 500 to about 900 mPa·s at 25° C., and a water content of less than 0.5% by weight, based on the total weight of castor oil;
(ii) 10 to 80% by weight, based on total weight of b), of a polyether polyol having an OH number of from 28 to 700, a functionality of from 2 to 8, a number average molecular weight of from about 240 to about 6,000, and a viscosity of from 50 to 35,000 mPa·s at 25° C., in which at least 70% by weight of the alkylene oxide content is propylene oxide; and
(iii) from 0 to 10% by weight, based on total weight of component b), of a low molecular weight diol or triol having an equivalent weight of 31 to 99; and
c) a catalyst for the reaction of hydroxyl groups with isocyanate groups; and optionally,
d) a filler.
The invention further relates to a process for producing a polyurethane geotextile composite liner with improved water resistance in which a geotextile is impregnated with such polyurethane.
The invention is also directed to a ditch or canal lined with such polyurethane geotextile composite and to a process for lining a ditch or canal with such composite.
The advantage of the polyurethane composition used to produce the composite of the present invention is that it has less tendency to foam. The geotextile polyurethane composite of the present invention will, therefore, be characterized by low water absorption. When such composite is used to line a ditch and/or a canal, water loss is kept at a minimum.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a polyurethane geotextile composite which is suitable for use as a liner with improved water resistance which is produced by impregnating a geotextile with a polyurethane composition that is a reaction product of a mixture which includes:
a) a liquid polyisocyanate having an isocyanate content of at least 10% by weight,
b) an isocyanate-reactive component which includes:
(i) from 20 to 90% by weight, based on total weight of b), of castor oil having an OH number of from about 160 to about 170, a viscosity of from about 500 to about 900 mPa·s at 25° C., and a water content of less than 0.5% by weight, based on the total weight of castor oil;
(ii) from 10 to 80% by weight, based on total weight of b), of a polyeth
Donaldson Marylyn
Estabrook W. Tracy
Guether Ralf
Markusch Peter H.
Sarpeshkar Ashok
Bayer Corporation
Gil Joseph C.
Mitchell Katherine
Mrozinski, Jr. John E.
Swann J. J.
LandOfFree
Polyurethane geotextile composite liner with improved water... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polyurethane geotextile composite liner with improved water..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyurethane geotextile composite liner with improved water... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3183473