HK1072440A - Two-ply polyurethane/geotextile composite and process for preparing the same - Google Patents

Description

Two-layer polyurethane geotextile composite material and preparation method thereof

Technical Field

The invention relates to a two-layer polyurethane geotextile (geotex) composite material and a preparation method thereof. In particular, the present invention relates to a two layer polyurethane geotextile composite comprising at least one layer of a rigid, dimensionally stable geotextile, at least one layer of a non-rigid, soft, and compliant geotextile, and a polyurethane composition bonding the rigid, dimensionally stable geotextile and the non-rigid geotextile. The invention also relates to a process for preparing a two-layer polyurethane geotextile composite in which a solidifiable liquid polyurethane composition is contacted with a rigid, dimensionally stable geotextile and a non-rigid, soft, compliant geotextile in a manner that bonds the two layers of polyurethane geotextile together to form the polyurethane geotextile composite. The invention also relates to canals or ditches lined with such a two-layer polyurethane geotextile composite.

Background

In recent years, management of natural resources has become an important issue in many countries around the world. Both to the saving of our resources and to the efforts to eliminate environmental pollution. Special attention is paid to waste leakage and water loss.

In water distribution using linerless irrigation ditches, losses are estimated to be at least 25%, and in some cases even more than 50%, depending on the surface porosity of the ditch and the distance traveled by the water. In most rural areas, ditches are formed by excavating the soil to the desired depth and width. Water flows through the trench during contact with the exposed natural surface. Such surfaces may be sand, clay, rock, etc., more commonly mixtures thereof. The porosity will depend on the ratio of the different components in the soil.

The loss of water in linerless irrigation ditches is only considered acceptable if the water supply is greater than demand. However, as civilization develops and population grows, more water is required for the production of more food and for the obvious increase in non-agricultural water. In addition to the larger domestic water supplies, the industry is now using large quantities of water in manufacturing and processing procedures.

The high consumption and the high cost of developing new water sources promote people to shift attention to water resource protection. A water-saving home appliance was developed. The industry also installs circulation purification systems to reduce water consumption.

Despite efforts to conserve water resources to reduce water consumption to some extent, water is still in short supply, especially in recent years, and severe drought has occurred in the united states and other countries. Given the best cost-effective water conservation opportunities and the readily available sources of water that have been developed, greater attention must be paid to improving the efficiency of water distribution systems.

Improvements have been made in water distribution. A limited number of ditches and canals have been lined with concrete and/or precast concrete pipes. Concrete is durable and has a long life when used properly. However, the laying and surfacing of concrete is rather costly and is subject to damage during curing due to adverse temperature conditions. Additionally, concrete is subject to frost damage, cracking and bulging, thereby causing leaks.

Polyvinyl chloride (PVC) pipes and PVC-lined trenches also find some degree of application in water distribution systems. PVC costs less than concrete. The limited durability of PVC liners can be improved to some extent by burying the pipeline several feet below the soil. The soil supports the pipeline, holds it in place and provides a tamper-proof cushion for it. However, whether concrete or PVC, considerable on-site preparation is required and often additional grading and backfilling is required after placement to complete the job.

There is a need for a low cost, easy to install liner composite that is both compliant and durable.

Trench liners are known. For example, U.S. Pat. No. 4,872,784 discloses a trench liner composed of a curable liquid mixture and a porous blanket. Suitable porous blankets include woven, knitted, and nonwoven structures.

Methods of forming composite liners for canals and ditches and apparatus for carrying out such methods are disclosed in, for example, U.S. Pat. nos. 4,872,784, 4,955,759, 4,955,760, 5,049,006, 5,062,740, 5,421,677, 5,607,998 and 5,654,064.

Us patent 5,654,064 discloses a liner for use in storing liquids. The liner is comprised of two non-biodegradable geotextiles and a water-swellable clay layer between the two geotextiles and a stitch-bonding means for joining the two geotextiles together. The stitch-bonding thread extends through the clay layers and connects the geotextiles into a whole. The water-swellable clay layer is bonded to at least one of the geotextiles.

U.S. Pat. No. 5,421,677 ("the 677 patent"), relates to an improved process for forming trench liners. The' 677 patent discloses the use of a mixture consisting of one or more polyisocyanates, a polyol mixture, one or more fillers and a catalyst. The mixture of the' 677 patent is disposed onto a geotextile to form a liquid polyurethane impregnated geotextile composite. The liquid polyurethane impregnated geotextile composition is then laid on the surface of the area to be lined and allowed to cure, thereby forming a polyurethane/geotextile composite.

The liquid polyurethane impregnated geotextile composite of the '677 patent is preferably produced using a machine such as that described in U.S. patent No. 4,872,784 ("the' 784 patent").

The geotextile used in the' 784 patent is preferably a rigid and dimensionally stable geotextile to avoid deformation or potential tearing when the liquid polyurethane impregnated geotextile is pulled from the apparatus. One or more layers of such rigid geotextiles can be used in the preparation of composite liners. However, due to the rigidity of the geotextile, wrinkles and seams are often formed in the overlapping (seam) areas, creating a potential risk of water leakage. Often, leaks occur through the gaps in the back of the liner and may cause delamination of the liner from the surface. Cutting wrinkles out of the liner and patching them is possible, but cutting and patching of composite liners not only weakens the liner, but also requires manual labor, which increases the cost of laying and/or maintaining the liner. One disadvantage of using a rigid, dimensionally stable composite material alone is that the thickness required to ensure that the geotextile has a sufficient thickness to allow the liquid polyurethane to penetrate and adhere to the surface of the ditch and/or canal is limited.

The problem of wrinkling becomes more severe in soil ditches (typically much more irregular surfaces than concrete ditches). Soil ditches also require liners with greater thickness and mechanical stability. Concerns about wrinkle thickness and mechanical stability cannot be addressed by rigid, dimensionally stable geotextiles.

For the reasons stated above, it would be desirable to develop a two-layer polyurethane geotextile composite that does not have the disadvantages described above. In particular, it would be desirable to develop a two layer polyurethane geotextile composite that can cover uneven surfaces, yet avoid wrinkling, and provide the thickness and mechanical stability required for an earthen canal.

Disclosure of Invention

The present invention relates to a two layer polyurethane geotextile composite in which a solidifiable liquid polyurethane composition bonds at least one layer of a rigid, dimensionally stable geotextile to at least one layer of a soft, compliant geotextile.

The invention also relates to a method for producing such a composite material, to a method for lining a trench or canal with such a composite material and to a trench and canal lined with such a composite material. The polyurethane composition that bonds the two different types of geotextiles is the reaction product of a mixture comprising:

a) a liquid polyisocyanate having an isocyanate group content of at least 10% by weight;

b) an isocyanate reactive component comprising one or more polyether polyols having 2 to 6 hydroxyl groups and a number average molecular weight of at least 250 to 8,000 and 0 to 10% by weight based on the total weight of b) of a low molecular weight diol or triol having a hydroxyl equivalent weight of about 31 to 99;

c) an organometallic catalyst; and

optionally, optionally

d) A filler.

The two-layer polyurethane geotextile composite can be prepared by the following steps: the solidifiable liquid polyurethane composition is applied to a rigid, dimensionally stable geotextile and/or a soft, pliable geotextile and the two different types of geotextile are contacted with each other, or one or both of the geotextiles are impregnated with polyurethane and the impregnated geotextile is contacted with the other geotextile, and the polyurethane is then allowed to cure.

The flexibility of the two-layer polyurethane geotextile composite allows the composite to be laid more efficiently on a surface, for example as a lining for ditches and/or canals whose surfaces are sometimes uneven. In addition, the use of two different types of geotextiles results in a strong and durable composite. The above and other advantages of the present invention will be better understood upon a study of the following description and appended claims.

Detailed Description

The present invention relates to a two-layer polyurethane geotextile composite in which a solidifiable liquid polyurethane composition bonds at least one layer of a rigid, dimensionally stable geotextile to at least one layer of a soft, compliant geotextile. The curable liquid polyurethane composition that bonds the two different types of geotextiles is the reaction product of a mixture comprising:

a) a liquid polyisocyanate having an isocyanate group content of at least 10% by weight;

b) an isocyanate reactive component comprising one or more polyether polyols having 2 to 6 hydroxyl groups and a number average molecular weight of at least 250 to 8,000 (also referred to herein as "high molecular weight polyether polyols") and 0 to 10% by weight based on the total weight of b) of a low molecular weight (i.e., number average molecular weight less than 250) diol or triol having a hydroxyl equivalent weight of about 31 to 99;

c) an organometallic catalyst, preferably up to 0.5 parts by weight per 100 parts by weight of polyol b); and

optionally, optionally

d) A filler.

The invention also relates to a method of making such a two-layer polyurethane geotextile composite comprising applying a solidifiable liquid polyurethane composition to a rigid, dimensionally stable geotextile and/or a soft, pliable geotextile and contacting the two different types of geotextile with each other, or impregnating one or both of the geotextiles with a polyurethane and contacting the impregnated geotextile with the other geotextile, and then allowing the polyurethane to cure.

The invention also relates to canals or ditches lined with such a two-layer polyurethane geotextile composite.

The term "geotextile" as used herein refers to any woven or nonwoven porous blanket or mat produced from natural or synthetic fibers. The terms "canal" and "canal" are used interchangeably to refer to any liquid-bearing surface having sloped sides or having depressions therein. Geotextiles are primarily used to line soil surfaces. However, such liners may also be used to line roofs, ponds, reservoirs, landfills, underground storage tanks, canals or ditches. Examples of geotextiles include woven or non-woven polypropylene, polyester, jute and cotton and fiberglass cloth.

The substantially rigid, dimensionally stable geotextile used in the present invention can be any known rigid, porous geotextile. Examples of suitable rigid, dimensionally stable geotextiles are woven or nonwoven fabrics made from polypropylene, polyester, cotton, jute, or glass fibers. The preferred substantially rigid geotextile is a non-woven polypropylene with excellent dimensional stability that can be readily penetrated by the curable liquid polyurethane composition. A more preferred substantially rigid geotextile is a non-woven polypropylene that is easily penetrated by the settable mixture and has excellent dimensional stability at a thickness of less than 1 mm.

The non-rigid geotextile used in the present invention includes any known substantially soft and pliable geotextile, and in particular any known porous fabric that can be readily saturated or impregnated with the solidifiable liquid polyurethane composition. Preferred soft and compliant geotextiles are polyester and polypropylene fabrics with a minimum thickness of 1 mm. A more preferred non-rigid geotextile is a polyester or polypropylene fabric with a minimum thickness of 1mm and a polished side.

Any known liquid isocyanate, so long as the isocyanate content is at least 10% by weight, preferably at least 20% by weight, and most preferably at least 30% by weight, can be used in the practice of the present invention. Suitable liquid organic polyisocyanates include aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates of the type described, for example, in W.Siefken, Justus LiebigsAnnanen der Chemie 562, pp.75-136. Such isocyanates include those of the formula Q (NCO)_nThose represented wherein n represents a number of from 2 to about 5, preferably 2 to 3, and Q represents an aliphatic hydrocarbon group of from 2 to about 18, preferably 6 to 10 carbon atoms, a cycloaliphatic hydrocarbon group of from 4 to about 15, preferably 5 to 10 carbon atoms, an araliphatic hydrocarbon group of from 8 to 15, preferably 8 to 13 carbon atoms, or an aromatic hydrocarbon group of from 6 to about 15, preferably 6 to 13 carbon atoms. Examples of suitable isocyanates include: ethylene diisocyanate, 1, 4-tetramethylene diisocyanate, 1, 6-hexamethylene diisocyanate, 1, 12-dodecane diisocyanate, cyclobutane-1, 3-diisocyanate, cyclohexane-1, 3-and 1, 4-diisocyanate and mixtures of these isomers; 1-isocyanato-3, 3, 5-trimethyl-isocyanatomethylcyclohexane ("isophorone diisocyanate" (see, for example, German published patent application 1,202,785 and U.S. Pat. No. 3,401,190)), 2, 4-and 2, 6-hexahydrotoluylene diisocyanate and mixtures of these isomers; dicyclohexylmethane-4, 4 ' -diisocyanate ("hydrogenated MDI" or "HMDI"), 2, 4-and 2, 6-tolylene diisocyanate and mixtures of these isomers ("TDI"), diphenylmethane-2, 4 ' -and/or-4, 4 ' -diisocyanate ("MDI"), polymethylene poly (phenylisocyanate) ("crude MDI") obtainable by condensation of aniline with formaldehyde and subsequent phosgenation (as described, for example, in british patents 878,430 and 848,671), norbornane diisocyanate (as described, for example, in U.S. patent 3,492,330), m-and p-isocyanatophenylsulfonyl isocyanates (of the type described in U.S. patent 3,454,606), perchlorinated aryl polyisocyanatesEsters (of the type described, for example, in U.S. Pat. No. 3,227,138), modified polyisocyanates containing carbodiimide groups (of the type described, for example, in U.S. Pat. No. 3,152,162), modified polyisocyanates containing urethane groups (of the type described, for example, in U.S. Pat. Nos. 3,394,164 and 3,644,457), modified polyisocyanates containing urethanate groups (of the type described, for example, in British patent 994,890, Belgian patent 761,616 and published Netherlands patent application 7,102,524), modified polyisocyanates containing isocyanurate groups (of the type described, for example, in U.S. Pat. Nos. 3,002,973, 1,022,789, 1,222,067 and 1,027,394 and German published applications 1,919,034 and 2,004,048), modified isocyanates containing urea groups (of the type disclosed in German patent 1,230,778), polyisocyanates containing biuret groups (of the type described, for example, in German patent 1,101,394, U.S. Pat. Nos. 3,124,605 and 3,201,372 and British patent 889,050), polyisocyanates obtained by telomerization (of the type described, for example, in U.S. Pat. 3,654,106), Polyisocyanates containing ester groups (of the type described, for example, in British patents 965,474 and 1,072,956, U.S. Pat. No. 3,567,763 and German patent 1,231,688), the reaction products of the above-mentioned isocyanates with acetals (described, for example, in German patent 1,072,385), and polyisocyanates containing polymerized fatty acid groups (of the type described in U.S. Pat. No. 3,455,883). It is also possible to use the distillation residues containing isocyanates which accumulate in the industrial scale production of isocyanates, optionally dissolved in one or more of the polyisocyanates mentioned above. Mixtures of the polyisocyanates described above may also be used.

In general, it is preferred to use readily available polyisocyanates such as 2, 4-and 2, 6-toluene diisocyanate and mixtures of isomers thereof ("TDI"), diphenylmethane diisocyanate ("MDI"), polymethylene poly (phenylisocyanates) of the kind obtained by condensation of aniline with formaldehyde and subsequent phosgenation ("crude MDI"), and polyisocyanates containing carbodiimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret groups ("modified polyisocyanates"). Aromatic polyisocyanates, especially the phosgenation products of commercially available aniline/formaldehyde condensates, are particularly preferred polyisocyanates. Polymethylene poly (phenylisocyanates) having an NCO content of from about 30 to 33% and a viscosity of from about 20 to 2,000mPa.s at 25 ℃ are one of the most preferred polyisocyanates.

Suitable high molecular weight isocyanate-reactive compounds for use as component b) include any known polyether polyols, especially any polyether polyol having from 2 to 6, preferably from 2 to 4, most preferably 2 or 3 hydroxyl groups and a number average molecular weight of at least 250 to about 8,000, preferably from about 400 to about 4,000, most preferably from about 400 to about 2,000.

Such polyether polyols, for example, those which can be prepared by polymerization of epoxides such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin, optionally in the presence of Lewis acids such as BF₃In the presence of an initiator, or by chemical addition of such epoxides, optionally added in admixture or sequentially to an initiating component containing an active hydrogen atom, such as water, an alcohol or an amine. Examples of suitable starting components include: ethylene glycol, 1, 3-or 1, 2-propanediol, 1, 2-, 1, 3-or 1, 4-butanediol, trimethylolpropane, 4' -dihydroxydiphenylpropane, aniline, ammonia, ethanolamine and ethylenediamine. Sucrose polyethers of the type described in, for example, German published applications 1,176,358 and 1,064,938 may also be used in the present invention. Polyethers containing a majority of primary hydroxyl groups (up to about 90% by weight, based on the total hydroxyl groups in the polyether) are also suitable for use. Polyethers modified with vinyl polymers, for example of the type obtained by polymerization of styrene and acrylonitrile in the presence of polyethers (for example, U.S. Pat. Nos. 3,383,351, 3,304,273, 3,523,093 and 3,110,695 and German patent 1,152,536) are also suitable, as are polybutadienes containing hydroxyl groups. Particularly preferred polyether polyols include polyoxyalkylene polyether polyols, such as polyoxyethylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, and polytetramethylene glycol, as well as polyoxypropylene-polyoxyethylene triols.

Other suitable polyether polyols for use in component b) include the so-called "PHD polyols", which can be prepared by reaction of an organic polyisocyanate, hydrazine and a polyether polyol. U.S. Pat. No. 3,325,421 discloses a process for preparing suitable PHD polyols by reacting a stoichiometric or substoichiometric amount (relative to diamine) of a polyisocyanate dissolved in a polyol having a molecular weight of at least 500 and a hydroxyl number of no greater than 225. See also U.S. Pat. nos. 4,042,537 and 4,089,835.

Polymer polyols may also be used as component b). The polymer polyol can be prepared by polymerizing styrene and acrylonitrile in the presence of a polyether. See, for example, U.S. Pat. Nos. 3,383,351, 3,304,273, 3,523,093, 3,652,639, 3,823,201, and 4,390,645.

Particularly preferred polyethers include polyoxypropylene polyethers which do not contain ethylene oxide units.

Mixtures of polyether polyols are also particularly advantageous for use in the practice of the present invention. Particularly advantageous polyether polyols include: (i) from about 5 to about 15 parts by weight (based on the total weight of the polyol) of a propylene oxide adduct of an alkanolamine, the adduct having a number average molecular weight of from about 250 to about 1,000; (ii) a propylene oxide adduct of a low molecular weight organic compound having about 3 to 6 hydroxyl groups, the adduct having a number average molecular weight of about 250 to 1,000; and (iii) a propylene oxide adduct of a low molecular weight diol, the adduct having a number average molecular weight of from about 250 to 3,000.

Any known low molecular weight organic diol or triol may optionally be included in the isocyanate-reactive component b) in an amount of up to 10% by weight. Suitable organic diols or triols include, for example, diols and triols having an equivalent weight of from about 31 to about 99. Examples of such diols and triols include: 2-methyl-1, 3-propanediol, ethylene glycol, 1, 2-and 1, 3-propanediol, 1, 3-and 1, 4-and 2, 3-butanediol, 1, 6-hexanediol, 1, 10-decanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, glycerol, trimethylolpropane, neopentyl glycol, cyclohexanedimethanol and 2, 2, 4-trimethylpentane-1, 3-diol. Preferred diols and triols include dipropylene glycol and tripropylene glycol.

The polyurethane-forming reaction mixture also includes a catalyst c) (i.e., a urethane catalyst) for catalyzing the reaction of isocyanate groups with hydroxyl groups. Such catalysts are well known in the art. Suitable catalysts include organometallic compounds. Preferred catalysts c) are organotin compounds. The organotin compounds preferably used are tin (II) salts of carboxylic acids, such as tin (II) acetate, tin (II) octoate, tin (II) ethylhexanoate and tin (II) laurate, and tin (IV) compounds, such as dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, dioctyltin diacetate and the like. Of course, any other urethane catalyst known to those skilled in the art of polyurethane chemistry may also be used.

The catalyst may be added separately to the polyurethane-forming reaction mixture or combined with the isocyanate-reactive component b) before combining the isocyanate-reactive component b) with the polyisocyanate.

However, catalysts capable of catalyzing the reaction between isocyanate groups and water (i.e., tertiary amine catalysts) are not employed in the polyurethane-forming reaction mixture.

The urethane catalyst is generally used in an amount of 0.0001 to 5 parts by weight, preferably about 0.001 to 0.1 part by weight, per 100 parts by weight of component b).

Optionally, any known filler may be included in the polyurethane-forming compounds of the present invention. Useful fillers include calcium carbonate, barium sulfate, diatomaceous earth, white powder, mica, glass fibers, liquid crystal fibers, glass flakes, glass spheres, aramid fibers, and carbon fibers. In addition, ground solid plastics (e.g., polyurethane scrap), rubber waste (e.g., from tires), or any kind of ground rubber may be used.

If a filler is used, it is either added to the polyisocyanate component a) or to the isocyanate-reactive component b) before the curable liquid mixture is formed, or it can be metered separately into the polyurethane-forming reaction mixture.

In the practice of the invention, the liquid polyisocyanate component a) is mixed with the isocyanate-reactive component b) in the presence of the urethane catalyst c), and optionally the filler d), in an equivalent ratio NCO: (OH + NH) of 1.4: 1 to 0.9: 1, preferably 1.1: 1.0 to 1.0: 1.0.

In one embodiment of the invention, a trench or canal is lined with a composite liner of the invention using a machine such as that described in U.S. Pat. No. 5,639,331 ("the' 331 patent").

The' 331 patent discloses a mobile trench liner installation equipped with storage tanks for supplying raw materials such as resins, catalysts, fillers, colorants or other additives. The reservoir is connected to the mixing chamber by means of a flexible conduit. The rate at which the ingredients are fed to the mixing chamber will vary depending on the particular formulation and the amount required for the particular area of the liner being formed. In the process of the present invention, the polyisocyanate, the isocyanate-reactive component, the catalyst and optionally the filler are mixed with one another in such a mixing chamber.

From the mixing chamber, the polyurethane composition is applied between a layer of rigid, dimensionally stable geotextile and a layer of soft, pliable geotextile. The geotextile is pulled from the vat containing the polyurethane composition through the adjustable die. The openings in the die ensure uniform distribution of the polyurethane composition on the geotextile surface, determine how much polyurethane is disposed on the geotextile, and also control the thickness of the polyurethane impregnated geotextile composite. The two layers of polyurethane impregnated geotextile are then cut to the desired length and laid in a canal or ditch where it conforms to its surface and cures to form two layers of polyurethane impregnated geotextile. The method ensures that the geotextile linings impregnated with polyurethane are laid between all sections of geotextile linings in a certain overlapping way, and a seamless and permanent flexible lining made of two-layer polyurethane composite material is obtained after curing.

In another embodiment of the invention, the polyurethane composition is applied by spraying onto the rigid, dimensionally stable geotextile using commercially available two-pack polyurethane spray equipment. The polyurethane impregnated rigid, dimensionally stable geotextile is then laid in a ditch or canal. A soft, compliant geotextile is then laid over the polyurethane impregnated rigid dimensionally stable geotextile, whereupon the liquid polyurethane composition is absorbed by the soft, compliant geotextile. The laminated geotextile conforms to its surface and cures to form a two-layer polyurethane geotextile composite. The rigid, dimensionally stable geotextile can also be first sized and laid in a canal or ditch and then impregnated with the polyurethane composition by spraying the polyurethane onto its surface. A soft, pliable geotextile is then laid over the polyurethane impregnated rigid, dimensionally stable geotextile. In such an embodiment, it is preferred that the geotextile be rolled (e.g., paint roller) while the polyurethane composition thereon is still in a liquid state, so that the mixture penetrates through the geotextile to the surface of the ditch or canal.

In another embodiment of the invention, the liquid polyurethane composition is applied (e.g., by spraying) to the surface to be lined (e.g., the concrete surface of a ditch or canal). The rigid, dimensionally stable geotextile is then contacted with the polyurethane-applied surface. And paving soft and soft geotextile on the rigid geotextile. The contact between the uncured polyurethane composition and both the rigid geotextile and the soft, pliable geotextile should be such that when the polyurethane is cured, the two different geotextiles will adhere to each other. This desired degree of contact can be ensured, for example, by applying a pressure to the soft compliant geotextile after it has been placed over the rigid geotextile sufficient to cause a certain amount of polyurethane to penetrate at least the surface of the soft compliant geotextile that is in direct contact with the rigid geotextile, but preferably should penetrate the entire surface of the soft compliant geotextile.

Prior art sprayable polyurethane formulations cannot be used in the present invention because they exhibit gel times of only a few seconds. To prepare a ditch or canal liner using the polyurethane geotextile composite, a gel time of at least 5 minutes, preferably greater than 10 minutes, is required.

Any of the processes described above may be repeated one or more times if it is desired to add additional layers of polyurethane composite material.

The thickness of the polyurethane geotextile composites of the present invention can vary over a wide range, but generally ranges from about 50 μm to about 500 μm.

The amount of polyurethane applied to the geotextile can vary, but typically the amount of polyurethane applied per square meter of geotextile is from 1kg to 20kg, preferably from 2kg to 5 kg.

It is desirable that several layers of polyurethane impregnated geotextile can be applied on top of each other, resulting in a composite of higher strength and dimensional stability. Such multi-layer composites are actually the preferred mode of lining an earthen canal or ditch.

The following examples further illustrate details for the preparation and use of the composite materials of the present invention.

Examples

The following materials are used in the examples given below.

Isocyanate A: polymethylene poly (phenylisocyanate) having an NCO content of about

31.5%, functionality 2.6, viscosity 200mPa.s at 25 ℃

Polyol 1: monoethanolamine-initiated propylene oxide polyether polyols having a hydroxyl number of

About 350, a functionality of about 3, and a number average molecular weight of about 480

Polyol 2: a glycerine initiated propylene oxide polyether polyol having a hydroxyl number of about

250, functionality of about 3, number average molecular weight of about 670

Polyol 3: propylene glycol initiated propylene oxide polyether polyol, hydroxyl number 56,

functionality of about 2, molecular weight of about 2000

Amine 1: bis (4-aminocyclohexyl) methane

Catalyst A: dimethyltin dilaurate, commercially available under the trade name Fomrez UL-

28, Witco products

Geotextile A: typar-3301, spunbonded polypropylene, 3 oz/sq yd, 12

Mil thick (Reemay)

And (3) geotextile B: FX-40HS, Polypropylene nonwoven, thermal bonding, 4 oz/Flat

Square code (Carthrage Mills)

Geotextile C: trevira spunbonded, model 1620, polyester, non-woven,

thermal bond, 5.7 ounces per square yard, 37 mils thick (Fluid)

Systems)

The following polyols were used in the examples:

polyol blend A10 pbw polyol 1

45pbw of polyol 2

44pbw of polyol 3

0.01pbw of catalyst A

Examples 1 to 3

99g of polyol blend A, 1g of amine A and 43.9g of isocyanate A were mixed and then poured onto a1 square foot piece of geotextile A. The reaction mixture was spread on the geotextile surface using a spatula, and then a1 square foot piece of a second geotextile (A, B or C) was placed over the liquid polyurethane and geotextile a. The polyurethane mixture was then evenly distributed between the geotextiles with a rubber roll and any excess polyurethane was also rolled off. The gel time of the polyurethane is 15-20 minutes, and the material is cured into a compact geotextile/polyurethane composite material within about 1 hour. The thickness of the composite material is 80-100 mils. The properties of the composite thus produced were measured and are shown in Table 1.

TABLE 1

	Example 1*	Example 2	Example 3
				Polyol blend A (g)	99	99	99
Isocyanate A (g)	43.9	43.9	43.9
				Amine 1(g)	1	1	1
Isocyanate index	105	105	105
				Catalyst A concentration (%)	0.01	0.01	0.01
Geotextile combination	2 geotextile A	1 geotextile A1 geotextile C	1 geotextile A1 geotextile B
				Tensile Strength (psi)	757	1284	1465
Elongation (%)	50	64	39
				Tear (pli)	126	105	109
Die "C" tear	196	205	248
				Puncture test	70	113	114

^*Comparative example

In examples 2 and 3, two-layer polyurethane geotextile composites within the scope of the present invention were prepared comprising a combination of one rigid, dimensionally stable geotextile (geotextile a) and one soft, compliant geotextile (geotextile B or C). The data presented in table 1 shows the performance advantage of a two layer polyurethane geotextile composite made from two layers of different types of geotextiles compared to a two layer geotextile combination of the same stiffness and dimensional stability, as shown in comparative example 1.

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims (27)

1. A two-layer polyurethane geotextile composite in which a rigid, dimensionally stable geotextile is bonded to a soft, pliable geotextile with a solidifiable liquid polyurethane composition that is the reaction product of a mixture comprising:

a) a liquid polyisocyanate having an isocyanate group content of at least 10% by weight;

b) an isocyanate reactive component comprising a polyether polyol having 2 to 6 hydroxyl groups and a number average molecular weight of at least 250 to about 8,000 and 0 to 10 weight percent based on the total weight of b) of a low molecular weight diol or triol having a hydroxyl equivalent weight of about 31 to 99;

c) a urethane catalyst; and

optionally, the step of (a) is carried out,

d) a filler.

2. The composite of claim 1 wherein the polyether polyol b) comprises a polyoxypropylene polyether having a number average molecular weight of from about 400 to about 4,000 and an average functionality of from 2 to 3.

3. The composite of claim 1, wherein the polyether polyol b) comprises:

(i) from about 5 to about 15 parts by weight of a propylene oxide adduct of an alkanolamine, the adduct having a number average molecular weight of from 250 to about 1,000;

(ii) a propylene oxide adduct of a low molecular weight organic compound having from about 3 to about 6 hydroxyl groups, the adduct having a number average molecular weight of from about 250 to 1,000; and

(iii) a propylene oxide adduct of a low molecular weight diol, the adduct having a number average molecular weight of from 250 to about 3,000.

4. The composite of claim 1 wherein catalyst c) comprises an organotin compound.

5. The composite material of claim 1, wherein the liquid polyisocyanate a) is an aromatic polyisocyanate.

6. The composite material of claim 1, wherein the liquid polyisocyanate a) is a polymethylene poly (phenylisocyanate) having an NCO-content of about 30 to 33% and a viscosity at 25 ℃ of about 20mpa.s to 2,000 mpa.s.

7. The composite of claim 1, wherein the rigid, dimensionally stable geotextile has a maximum thickness of 1 mm.

8. The composite of claim 1, wherein the soft, compliant geotextile has a minimum thickness of 1 mm.

9. The composite of claim 1, wherein the soft, compliant geotextile has at least one side that is polished.

10. The composite of claim 1 wherein the curable liquid polyurethane composition does not include filler d).

11. The composite of claim 1, wherein the polyether polyol b) does not comprise a low molecular weight diol or triol.

12. A method of producing a two-layer polyurethane geotextile composite comprising:

(1) applying a solidifiable liquid polyurethane composition to at least one of a rigid, dimensionally stable geotextile or a soft, pliable geotextile, the solidifiable liquid polyurethane composition being the reaction product of a mixture comprising:

a) a liquid polyisocyanate having an isocyanate group content of at least 10% by weight;

b) an isocyanate reactive component comprising a polyether polyol having 2 to 6 hydroxyl groups and a number average molecular weight of at least 250 to about 8,000 and 0 to 10 weight percent based on the total weight of b) of a low molecular weight diol or triol having a hydroxyl equivalent weight of about 31 to 99;

c) a urethane catalyst; and

optionally, the step of (a) is carried out,

d) a filler material;

(2) contacting a rigid geotextile with a soft, pliable geotextile in a manner such that the polyurethane composition can bond the geotextiles; and

(3) the polyurethane composition is allowed to cure.

13. The process of claim 12, wherein the polyether polyol b) comprises a polyoxypropylene polyether having a number average molecular weight of from about 400 to about 4,000 and an average functionality of from 2 to 3.

14. The process of claim 12, wherein the polyether polyol b) comprises:

(i) from about 5 to about 15 parts by weight of a propylene oxide adduct of an alkanolamine, the adduct having a number average molecular weight of from 250 to about 1,000;

(ii) a propylene oxide adduct of a low molecular weight organic compound having from about 3 to about 6 hydroxyl groups, the adduct having a number average molecular weight of from about 250 to 1,000; and

(iii) a propylene oxide adduct of a low molecular weight diol, the adduct having a number average molecular weight of from 250 to about 3,000.

15. The process of claim 12 wherein catalyst c) is an organotin compound.

16. The process of claim 12 wherein the liquid polyisocyanate a) is an aromatic polyisocyanate.

17. The process of claim 12 wherein the liquid polyisocyanate a) is a polymethylene poly (phenylisocyanate) having an NCO-content of about 30 to 33% and a viscosity at 25 ℃ of about 20 to 2,000 mpa.s.

18. The method of claim 12 wherein the rigid, dimensionally stable geotextile has a maximum thickness of 1 mm.

19. The method of claim 12, wherein the soft, compliant geotextile has a minimum thickness of 1 mm.

20. The method of claim 12, wherein the soft, compliant geotextile has at least one side that is polished.

21. The method of claim 12 wherein the curable liquid polyurethane composition does not include filler d).

22. The process of claim 12 wherein component b) does not comprise a low molecular weight diol or triol.

23. The method of claim 12, wherein two or more layers of polyurethane composite liners are laid one on top of the other.

24. The method of claim 12 wherein in step a) the polyurethane composition is applied to a rigid geotextile.

25. A method of forming a two-layer polyurethane geotextile composite, comprising:

(1) spraying the polyurethane composition onto the concrete surface of a ditch or canal;

(2) contacting a rigid, dimensionally stable geotextile with the polyurethane-coated surface;

(3) paving soft and soft geotextile on the rigid geotextile;

(4) ensuring that the polyurethane will contact the soft and pliable geotextile to the extent that the polyurethane can bond the rigid geotextile and the soft geotextile together; and

(5) allowing the polyurethane to cure to form a polyurethane geotextile composite, the polyurethane composition comprising a reaction product of a mixture comprising:

a) a liquid polyisocyanate having an isocyanate group content of at least 10% by weight;

b) an isocyanate reactive component comprising a polyether polyol having 2 to 6 hydroxyl groups and a number average molecular weight of at least 250 to 8,000 and 0 to 10 weight percent based on the total weight of b) of a low molecular weight diol or triol having a hydroxyl equivalent weight of about 31 to 99;

c) a urethane catalyst; and

optionally, the step of (a) is carried out,

d) a filler.

26. A canal or ditch lined with a two-layer polyurethane geotextile composite produced by the steps of:

(1) disposing a polyurethane composition between at least one layer of a rigid, dimensionally stable geotextile and at least one layer of a soft, pliable geotextile;

(2) spreading the product of (1) on the surface of a canal or ditch while the polyurethane composition is not completely cured;

(3) conforming the polyurethane/geotextile product laid in (2) to the surface of a canal or ditch; and

(4) allowing the polyurethane between the geotextile layers to fully cure to form a polyurethane geotextile composite liner, wherein the polyurethane composition configured in (1) is the reaction product of a mixture comprising:

a) a liquid polyisocyanate having an isocyanate group content of at least 10% by weight;

b) an isocyanate reactive component comprising a polyether polyol having 2 to 6 hydroxyl groups and a number average molecular weight of at least 250 to 8,000 and 0 to 10 weight percent based on the total weight of b) of a low molecular weight diol or triol having a hydroxyl equivalent weight of about 31 to 99;

c) a urethane catalyst; and

optionally, the step of (a) is carried out,

d) a filler.

27. The canal or ditch of claim 26, wherein the two-layer polyurethane composite is applied to the surface of the canal or ditch in such a manner that the rigid, dimensionally stable geotextile is in direct contact with the canal or ditch while the polyurethane is not fully cured.