EP1986845A1 - Système de confinement cellulaire multicouche résistant aux uv - Google Patents

Système de confinement cellulaire multicouche résistant aux uv

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Publication number
EP1986845A1
EP1986845A1 EP07757728A EP07757728A EP1986845A1 EP 1986845 A1 EP1986845 A1 EP 1986845A1 EP 07757728 A EP07757728 A EP 07757728A EP 07757728 A EP07757728 A EP 07757728A EP 1986845 A1 EP1986845 A1 EP 1986845A1
Authority
EP
European Patent Office
Prior art keywords
polymeric
confinement system
cellular confinement
layer
strip
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07757728A
Other languages
German (de)
English (en)
Inventor
Izhar Halahmi
Oded Erez
Adi Erez
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
PRS Mediterranean Ltd
Original Assignee
PRS Mediterranean Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by PRS Mediterranean Ltd filed Critical PRS Mediterranean Ltd
Publication of EP1986845A1 publication Critical patent/EP1986845A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00—Excavations; Bordering of excavations; Making embankments
    • E02D17/20—Securing of slopes or inclines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/10—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material
    • B32B3/12—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure

Definitions

  • the present disclosure generally relates to a polymeric cellular confinement system which can be filled with soil, concrete, aggregate, earth materials, and the like. More specifically, the present disclosure concerns a cellular confinement system characterized by improved durability against damage generated by ultraviolet light, humidity, aggressive soils, and combinations thereof.
  • Plastic soil reinforcing articles especially cellular confinement systems (CCSs) are used to increase the load bearing capacity, stability and erosion resistance of geotechnical materials such as soil, rock, sand, stone, peat, clay, concrete, aggregate and earth materials which are supported by said CCSs.
  • CCSs cellular confinement systems
  • CCSs comprise a plurality of high density polyethylene (HDPE) strips in a characteristic honeycomb-like three-dimensional structure. The strips are welded to each other at discrete locations to achieve this structure.
  • Geotechnical materials can be reinforced and stabilized within or by CCSs.
  • the geotechnical material that is stabilized and reinforced by the said CCS is referred to hereinafter as geotechnical reinforced material (GRM).
  • GRM geotechnical reinforced material
  • the surfaces of the CCS may be embossed to increase friction with the GRM and decrease relative movement between the CCS and the GRM.
  • the CCS strengthens the GRM by increasing its shear strength and stiffness as a result of the hoop strength of the cell walls, the passive resistance of adjacent cells, and friction between the CCS and GRM. Under load, the CCS generates powerful lateral confinement forces and soil-cell wall friction. These mechanisms create a bridging structure with high flexural strength and stiffness. The bridging action improves the long-term load-deformation performance of common granular fill materials and allows dramatic reductions of up to 50% in the thickness and weight of structural support elements. CCSs may be used in load support applications such as road base stabilization, intermodal yards, under railroad tracks to stabilize track ballast, retaining walls, to protect GRM or vegetation, and on slopes and channels.
  • HDPE refers hereinafter to a polyethylene characterized by density of greater than 0.940 g/cm 3 .
  • MDPE medium density polyethylene
  • LLDPE linear low density polyethylene
  • the plastic walls of the CCSs may become damaged during service and use in the field by UV light, heat, and humidity (UHH).
  • UHH UV light, heat, and humidity
  • the damage results in brittleness, decreased flexibility, toughness, impact and puncture resistance, poor tear resistance, and discoloration.
  • heat damage to the CCS is significant in hot areas on the globe.
  • the term "hot areas” refers to areas located 42 degrees latitude on either side of the equator and especially along the desert belt. Hot areas include, for example, North Africa, southern Spain, the Middle East, Arizona, Texas, Louisiana, Florida, Central America, Brazil, most of India, southern China, Australia, and part of Japan. Hot areas regularly experience temperatures above 35°Cand intensive sunlight for periods of up to 14 hours each day. Dark surfaces of plastics exposed to direct sunlight can reach temperatures as high as +90°C.
  • CCSs are usually immobilized or anchored to the GRM by wedges, tendons, bars, or anchors. This immobilization is especially crucial when the CCS is used to reinforce a slope.
  • the wedges, tendons, bars, or anchors are usually made of iron, and can be heated by direct sunlight to temperatures that may exceed 60-85 0 C. The high conductivity of iron also transmits the heat to the buried portion of the CCS.
  • These anchor points are subjected to severe stress concentrations. Without UHH protection, these anchor points may fail before any significant damage is observed in the rest of the CCS.
  • Stress is also generated at the welds between the strips making up the CCS. Stress can be applied from compression when humans walk over the CCS during installation, before and while it is filled with GRM, or when GRM is dumped onto the CCS to fill the cells. GRM can also expand when it becomes wet or when water already in the GRM freezes in cold weather. In addition, GRM has a coefficient of thermal expansion (CTE) about 5-10 times lower than the HDPE used to make the strips. Thus, the HDPE will expand much more than the GRM; this causes stress along the CCS walls and especially at the welds.
  • CTE coefficient of thermal expansion
  • Some CCSs are pigmented to shades similar to the GRM they support. These include light colored products and custom-shaded CCSs, such as soil-like colored CCSs, grass-like colored CCSs and peat-like colored CCSs.
  • UV absorbers such as benzotriazoles and benzophenones
  • radical scavengers such as hindered amine light stabilizers (HALS)
  • antioxidants Usually, "packages" of more than one additive are provided to the polymer.
  • the additives are introduced into the polymer, usually as a master batch or holkobatch, a dispersion, and /or solution of the additives in a polymer carrier or a wax carrier.
  • the amount of additives in the polymer used to make the CCS depends on the life-time required for the CCS. To provide protection for periods of about 5 years, the amount of additives needed is less than if protection for a period of 10 years or more is required. Because additives leach out of the polymer, evaporate, or hydrolyze over time, the actual amount of additives required for protection over a long period of time is about 2 to 10 times greater than the amount that is needed for short term protection needs. In other words, the amount of additives added to the polymer must compensation for leaching, evaporation, and hydrolysis and is thus significantly greater than amount needed for short term protection. Moreover, as the heat and humidity where the CCS is to be used increases, more additives need to be added to the polymer to maintain its protection level.
  • the additives are generally dispersed or otherwise dissolved fairly evenly throughout the entire cross-section of the polymeric strips used to make the CCS. However, most interaction between the additives and the UHH damage-causing agents takes place in the outermost volume, i.e. 10 to 200 microns, of the polymeric strip or film.
  • U.S. Patent No. 6,953,828 discloses a membrane, including a geomembrane, stabilized against UV.
  • the patent relates to polypropylene and very low density polyethylene compositions that are effective as membranes, but are not practical for CCSs.
  • Polypropylene is too brittle at sub-zero temperatures.
  • Very low density polyethylene is too weak for use in a CCS because it tends to creep under moderate loads. Once a CCS creeps, the integrity of the CCS and GRM is disrupted and structural performance is irreversibly damaged.
  • polypropylene requires a large loading of additives to overcome leaching and hydrolysis; this results in an uneconomical polymer.
  • U.S. Patent No. 6,872,460 teaches a bi-layer polyester film structure, wherein UV absorbers and stabilizers are introduced into one or two layers.
  • Various grades of polyesters are generally applicable for geo-grids, which are two-dimensional articles used to reinforce soil, such as a matrix of reinforcing tendons. Geo-grids are usually buried underground and thus not exposed to UV light. In contrast, CCSs are three- dimensional and are usually partially exposed above ground level, thus exposed to UV light. Polyesters are generally unsuitable for CCSs due to their stiffness, poor impact and puncture resistance at ambient and especially at sub-zero temperatures, medium to poor hydrolytic resistance (especially when in direct contact with basic media such as concrete and calcined soils), and their overall cost. Again, polyesters require a large loading of additives to overcome leaching and hydrolysis; this results in an uneconomical polymer.
  • the actual amount of additive required generally matches the theoretical calculated required amount.
  • thicker strips characterized by thickness of more than about 750 microns - that is usually the case with structural geotechnical reinforcing elements - CCS as example
  • the actual total amount of additive required is generally much higher than the theoretical calculated required amount.
  • the total amount of additive required is generally 5 to 10 times higher than the theoretical calculated required amount.
  • UHH-protecting additives are very expensive relative to the cost of the polymer.
  • polyethylene is one of the most popular materials for use, due its balance of cost, strength, flexibility at temperatures as low as minus 60 0 C, and ease of processing in standard extrusion equipment.
  • polyethylene is moderately resistant against UV light and heat.
  • polyethylene is susceptible to degradation within one year to a degree that is unacceptable for commercial use.
  • PE is still inferior relatively to more UV-resistant polymers, such as ethylene-acrylic ester copolymers and terpolymers.
  • polymers that exhibit higher UV and heat resistance such as acrylic and methacrylic ester copolymers and terpolymers, and specifically ethylene- acrylic ester copolymers and terpolymers, are very suitable to commercial application from the standpoint of UHH resistance.
  • acrylic and methacrylic ester copolymers and terpolymers and specifically ethylene- acrylic ester copolymers and terpolymers
  • their relatively high cost and relatively low modulus and strength characteristics limit their wide-scale use in CCS applications.
  • the present disclosure is directed to a geotechnical article, especially a cellular confinement system (CCS), which exhibits high durability against UV light, heat, and humidity, for periods of at least 2 years.
  • CCS cellular confinement system
  • the CCS exhibits such durability for at least 10 years.
  • the CCS exhibits such durability for at least 20 years and up to 100 years.
  • durability is meant lack of chalking or cracking, and retention of original color, surface integrity, strength, modulus, elongation to break, puncture resistance, creep resistance, and weld strength.
  • the CCS comprises a plurality of polymeric strips.
  • Each polymeric strip comprises at least one inner polymeric layer and at least one outer polymeric layer.
  • the at least one outer polymeric layer is more resistant to UV light, humidity, or heat (UHH), than the at least one inner polymeric layer.
  • Each polymeric layer comprises at least one kind of polymer.
  • the at least one outer polymeric layer further comprises a UV absorber or a hindered amine light stabilizer (HALS).
  • the UV absorber blocks and prevents the harmful UV light from penetrating to the at least one inner polymeric layer.
  • the HALS deactivates harmful radicals generated in the outer layer(s) from diffusion into the inner layer(s) of the polymeric strip.
  • a polymeric layer comprises an additive selected from the group consisting of antioxidants, pigments, and dyes.
  • At least one polymeric layer may comprise a filler.
  • the filler has higher heat conductivity than the polymer of the polymeric layer.
  • At least one layer of the polymeric strip comprises a pigment or dye.
  • the layer has a color similar to the GRM being supported by the CCS.
  • the color is not black or dark grey.
  • the CCS can be used for reinforcing a GRM.
  • Other CCSs, and devices are also disclosed. Methods of making and using the polymeric strip and/or CCS are also provided. These and other embodiments are described in more detail below.
  • FIGURE 1 is a perspective view of a single layer CCS.
  • FIGURE 2 is a perspective view of a cell containing a geotechnical reinforced material (GRM).
  • GEM geotechnical reinforced material
  • FIGURE 3 is a perspective view of a cell containing a GRM and a wedge.
  • FIGURE 4 is a perspective view of a cell containing a tendon.
  • FIGURE 5 is a perspective view of a cell containing a tendon and lockers.
  • FIGURE 6 is a perspective view of an exemplary embodiment of a cell including a reinforced wall portion.
  • the present disclosure relates to a cellular confinement system (CCS) comprising a plurality of polymeric strips and having high long-term durability for use in outdoor applications.
  • Each strip comprises at least one outer polymeric layer and at least one inner polymeric layer.
  • the outer polymeric layer is more UHH resistant than the inner polymeric layer.
  • the outer polymeric layer is more resistant against UV light, humidity, or heat (UHH) than virgin HDPE.
  • VHH UV light, humidity, or heat
  • the term "virgin HDPE” refers to any HDPE received from a reactor before it is mixed with any UV absorber or HALS additive. It is noted that any polymer from a reactor generally already contains 200-1000 ppm antioxidant.
  • FIGURE 1 is a perspective view of a single layer CCS.
  • the CCS 10 comprises a plurality of polymeric strips 14. Adjacent strips are bonded together by discrete physical joints 16. The bonding may be performing by bonding, sewing or welding, but is generally done by welding. The portion of each strip between two joints 16 forms a cell wall 18 of an individual cell 20. Each cell 20 has cell walls made from two different polymeric strips.
  • the strips 14 are bonded together to form a honeycomb pattern from the plurality of strips. For example, outside strip 22 and inside strip 24 are bonded together by physical joints 16 which are regularly spaced along the length of strips 22 and 24. A pair of inside strips 24 is bonded together by physical joints 32. Each joint 32 is between two joints 16.
  • an end weld 26 (also considered a joint) is made a short distance from the end 28 to form a short tail 30 which stabilizes the two polymeric strips 22, 24.
  • the CCS 10 can be reinforced and immobilized relative to the ground in at least two different ways.
  • Apertures 34 can be formed in the polymeric strips such that the apertures share a common axis.
  • a tendon 12 can then be extended through the apertures 34.
  • the tendon 12 reinforces the CCS 10 and improves its stability by acting as a continuous, integrated anchoring member that prevents unwanted displacement of the CCS 10.
  • Tendons may be used in channel and slope applications to provide additional stability against gravitational and hydrodynamic forces and may be required when an underlayer or naturally hard soil/rock prevents the use of stakes.
  • a wedge 36 can also be used to anchor the CCS 10 to the substrate to which it is applied, e.g., to the ground.
  • the wedge 36 is inserted into the substrate to a depth sufficient to provide an anchor.
  • the wedge 36 can have any shape known in the art (i.e., the term "wedge” refers to function, not to shape).
  • the tendon 12 and wedge 36 as shown are simply a section of iron or steel rebar, cut to an appropriate length. They can also be formed of a polymeric material. They can be formed from the same composition as the CCS itself. It may also be useful if the tendon 12 and/or wedge 36 has greater rigidity than the CCS 10.
  • a sufficient number of tendons 12 and/or wedges 36 are used to reinforce / stabilize the CCS 10. It is important to note that tendons and/or wedges should always be placed against the cell wall, not against a weld. Tendons and/or wedges have high loads concentrated in a small area and because welds are relatively weak points in the CCS, placing a tendon or wedge against a weld increases the likelihood that the weld will fail.
  • Additional apertures 34 may also be included in the polymeric strips, as described in U.S. Patent No. 6,296,924. These additional apertures increase frictional interlock with the GRM by up to 30%, increase root lock-up with vegetated systems as roots grow between the cells 20, improve lateral drainage through the strips to give better performance in saturated soils, and promote a healthy soil environment. Reduced installation and long-term maintenance costs may also occur. In addition, such CCSs are lighter and easier to handle compared to CCSs with solid walls.
  • FIGURE 2 is a perspective view of a single cell 20 containing a geotechnical reinforced material (GRM).
  • the cell 20 is depicted as it might appear when the CCS is located on a slope (indicated by arrow A), so that the GRM retained within the cell 20 has settled substantially horizontally (i.e. flat relative to the earth's surface), while the cell walls 14 of the CCS 10 are substantially perpendicular to the slope A on which the CCS is located. Because the cell walls 14 are not aligned horizontally with the GRM, the GRM settles substantially on the down-slope cell wall and an "empty area" is left on the up-slope cell wall.
  • GRM geotechnical reinforced material
  • the cell walls 14 are subject to the forces F1 and F2.
  • force F1 (exerted by the weight of the GRM) and force F2 (exerted by the empty area of an adjacent down-slope cell) are not balanced.
  • Force F1 is greater than force F2.
  • This unbalanced force stresses the joints 16.
  • the GRM exerts a separation force F3 against joints 16 as well. This separation force results from the mass of the GRM and natural forces. For example, the GRM will expand during humid periods as it retains water. The GRM will also expand and contract, e.g. from repeated freeze-thaw cycles of water retained within the cell 20. This shows the importance of a strong weld at each joint 16.
  • FIGURE 3 is a perspective view of a single cell 20 containing a geotechnical reinforced material (GRM) and a wedge 36.
  • the wedge 36 applies an additional force F4 on the up-slope cell wall to aid in balancing the forces on the cell walls 14.
  • the additional force is applied on a localized part of the up-slope cell wall and can be detrimental to the cell wall if it is not sufficiently strong and creep-resistant.
  • FIGURES 4 and 5 are perspective views of a single cell 20 containing a tendon 12.
  • the tendon 12 extends through apertures 34 in the strips 14 and is used to stabilize the CCS 10, especially in those situations where wedges 36 cannot be used. Stress is localized in the strips 14 around the apertures 34 as well.
  • the tendon 12 may have a different CTE from the strips 14.
  • GRM or water / ice can infiltrate the aperture 34 as well; expansion then increases stress and can damage the integrity of the strip 14.
  • lockers 38 can be used to spread the stress over a greater area, but the stress still exists. Use of a locker 38 provides added protection against failure in the long term.
  • FIGURE 6 is a perspective view of an exemplary embodiment of a cell including a reinforced wall portion.
  • a wedge 36 is located inside the cell 20. As discussed in reference to FIGURE 3, the wedge 36 applies additional force on a localized part of the up-slope cell wall and can be detrimental to the cell wall if it is not sufficiently strong and creep-resistant.
  • a reinforced wall portion 40 having a width greater than that of the wedge 36 is provided between the wedge 36 and the up-siope cell wall. Like the locker 38, the reinforced wall portion 40 spreads the stress over a greater area of the cell wall.
  • the reinforced wall portion 40 extends beyond the upper edge of the wall and is folded down over the far side of the wall, further increasing the strength of the overall wedge-contacting portion of the wall. In other embodiments, the reinforced wall portion 40 may also have an aperture 34 to accommodate the use of a tendon 12.
  • the reinforced wall portion 40 is attached to the wall with an appropriate adhesive, e.g., a pressure-sensitive adhesive or a curable adhesive.
  • the reinforced wall portion 40 may be attached to the wall by a welding operation, particularly ultrasonic welding, or sewing, performed onsite.
  • the reinforced wall portion 40 may be made from any suitable material. In particular embodiments, it is made from the same material as the cell wall. If desired, the reinforced wall portion 40 may also be more rigid than the wall to bear more of the stress itself.
  • FIGURE 7 is a view of an exemplary polymeric strip used in the CCS of the present disclosure.
  • the polymeric strip 200 comprises at least one outer polymeric layer 210 and at least one inner polymeric layer 220.
  • a polymeric strip having two outer polymeric layers 210 is shown.
  • Dispersed within at least one outer polymeric layer 210 is a UV absorber 230 or a hindered amine light stabilizer 240.
  • the at least one outer polymeric layer of the polymeric strip comprises a UV absorber or a hindered amine light stabilizer (HALS).
  • the UV absorber may be an organic UV absorber, such as a benzotriazole UV absorber or benzophenone UV absorber.
  • the UV absorber may also be an inorganic UV absorber.
  • the at least one outer polymeric layer may comprise further additives.
  • the additive is selected from the group consisting of heat stabilizers, antioxidants, pigments, dyes, and carbon black.
  • the polymeric strip may comprise more than one outer polymeric layer.
  • the polymeric strip comprises a first outer polymeric layer and a second outer polymeric layer.
  • the inner polymeric layer(s) lies between the first outer polymeric layer and the second outer polymeric layer.
  • Each outer polymeric layer comprises a greater number of additives than the inner polymeric layer(s).
  • the polymeric strip comprises a first outer polymeric layer and a second outer polymeric layer.
  • One outer polymeric layer comprises a greater total concentration of UV absorbers and HALS additives than the other outer polymeric layer.
  • the polymeric strip is a single-layer strip.
  • the additive content in the outer polymeric layer(s) is sufficient to provide protection to the polymeric strip for a period of 2 to about 100 years.
  • the term "about” refers hereinafter to a value 20% lower or higher than the given value modified by the term “about.”
  • the amount of additives provides sufficient protection to the polymeric strip for a period of at least 2 years.
  • the amount of additives provides sufficient protection to the polymeric strip for a period at least 5 years.
  • the amount of additives provides sufficient protection to the polymeric strip for at least 20 years and up to 50 years, regardless of weather conditions such as humidity, temperature, and UV light intensity.
  • sufficient protection refers to the ability of the polymeric strip to retain both (i) its color and shade; and (ii) its mechanical characteristics for a period of 2 to 100 years within at least 50% of the polymeric strip's original color, shade color, or mechanical characteristics.
  • the polymeric strip retains at least 80% of its original color, shade color, or mechanical characteristics.
  • the outer polymeric layer(s) comprises a UV absorber.
  • the UV absorber is organic and is a benzotriazole or a benzophenone commercially available as, for example, TinuvinTM, manufactured by Ciba, and CyasorbTM, manufactured by Cytec.
  • the outer polymeric layer(s) may also comprise a hindered amine light stabilizer (HALS) alone or with the UV absorber.
  • HALS are molecules which provide long term protection against free radicals and light-initiated degradation. In particular, HALS do not contain phenolic groups. Their limiting factor is the rate at which they leach out or are hydrolyzed.
  • the organic UV absorber and HALS together are present in the amount of from about 0.01 to about 2.5 weight percent, based on the total weight of the layer.
  • the outer polymeric layer(s) may also comprise an inorganic UV absorber.
  • the UV absorber has the form of solid particles. Solid particles are characterized by negligible solubility in polymer and water and negligible volatility, and thus do not tend to migrate out or be extracted from the layer(s). The particles may be micro-particles, (e.g. from about 1 to about 50 micrometers in average diameter), sub-micron particles (e.g. from about 100 to about 1000 nanometers in average diameter), or nanoparticles (e.g. from about 5 to about 100 nanometers in average diameter).
  • the UV absorber comprises inorganic UV- absorbing solid nanoparticles.
  • UV-absorbing solid nanoparticles are also transparent in the visible spectrum and are distributed very evenly. Therefore, they provide protection without any contribution to the color or shade of the polymer. Solid particles are also very insoluble in water, improving the durability of the polymer.
  • the UV-absorbing nanoparticles comprise a material selected from the group consisting of titanium salts, titanium oxides, zinc oxides, zinc halides, and zinc salts.
  • the UV-absorbing nanoparticles are titanium dioxide.
  • UV-absorbing particles examples include SACHTLEBENTM Hombitec RM 130F TN, by Sachtleben, ZANOTM zinc oxide by Umicore, NanoZTM zinc oxide by Advanced Nanotechnology Limited and AdNano Zinc OxideTM by Degussa.
  • UV- absorbing particles may be present in a loading of from about 0.01 to about 85 weight percent, by weight of the polymeric layer.
  • inorganic UV- absorbing particles have a loading of from about 0.1 to about 50 weight percent, based on the total weight of the polymer layer.
  • the polymeric layer comprises an inorganic UV absorber, HALS, and an optional organic UV absorber.
  • the inner polymeric layer(s) does not contain any organic UV absorbers, inorganic UV absorbers, or HALS additives.
  • the inner polymeric layer(s) may comprise organic UV absorbers and HALS together in an amount of from greater than 0 to about 0.5 weight percent, based on the total weight of the layer.
  • the inner polymeric layer(s) may also comprise inorganic UV absorbers in an amount of from 0 to about 0.5 weight percent, based on the total weight of the layer.
  • Any layer may further comprise an antioxidant.
  • Specific antioxidants which may be used include hindered phenols, phosphites, phosphates, and aromatic amines.
  • Any layer may further comprise a pigment or dye. Any suitable pigment or dye may be used which does not significantly adversely affect the desired properties of the overall polymeric strip.
  • at least one layer of the polymeric strip (generally an outer polymeric layer) is colored so as to be about the color of the GRM supported by the polymeric strip. Generally, the color is other than black or dark gray, especially any color which is not in the gray scale.
  • the colored polymeric layer need not be a uniform color; patterns of color (such as camouflage) are also contemplated.
  • the polymer strip may have a vivid color, such as red, yellow, green, blue, or mixtures thereof, and mixtures thereof with white or black, as described by CIELAB color coordinates.
  • a preferred group of colors and shades are brown (soil-like), yellow (sand-like), brown and gray (peat-like), off-white (aggregate like), light gray (concrete-like), green (grass-like), and a multi-color look which is stained, spotted, grained, dotted or marble-like.
  • Such colors have the utilitarian feature of allowing the CCS to be used in applications where the CCS is visible (i.e. not buried or covered by fill material).
  • the CCS can be used in terraces where the outer layers are visible, but can be colored to blend in with the environment.
  • the polymeric strip contains a pigment or dye, but does not contain carbon black.
  • carbon black is considered a UV absorber rather than a pigment.
  • a polymeric layer may further comprise a filler.
  • the polymeric layer may comprise from about 1 to about 70 weight percent of filler, based on the total weight of the polymeric layer. In further embodiments, the polymeric layer comprises from about 10 to about 50 weight percent of filler or from about 20 to about 40 weight percent of filler, based on the total weight of the polymeric layer.
  • the filler may be in the form of fibers, particles, flakes, or whiskers. The filler may have an average particle size of less than about 50 microns. In further embodiments the filler has an average particle size of less than about 30 microns. In further embodiments, the filler has an average particle size of less than about 10 microns.
  • the filler is selected from the group consisting of metal oxides, metal carbonates, metal sulfates, metal phosphates, metal silicates, metal borates, metal hydroxides, silica, silicates, aluminates, alumosilicates, fibers, whiskers, industrial ash, concrete powder or cement, and natural fibers such as kenaf, hemp, flax, ramie, sisal, newprint fibers, paper mill sludge, sawdust, wood flour, carbon, aramid, or mixtures thereof.
  • the filler is a mineral selected from the group consisting of calcium carbonate, barium sulfate, dolomite, alumina trihydrate, talc, bentonite, kaolin, wollastonite, clay, and mixtures.
  • the filler may also be surface treated to enhance compatibility with the polymer used in the polymeric layer.
  • the surface treatment comprises a sizing agent or coupling agent selected from the group consisting of fatty acids, esters, amides, and salts thereof, silicone containing polymer or oligomer, and organometallic compounds such as titanates, silanes, and zirconates.
  • the filler has higher heat conductivity than the polymer of the polymeric layer.
  • the temperature of the polymer layer can increase significantly relative to the air nearby on a hot day from a combination of convection and direct sunlight absorption (i.e., the polymer layer will be more than 3O 0 C higher than the air temperature). If the polymer layer has high heat conductivity, its temperature will only slightly increase relative to the air nearby (i.e., by about 1 to 3O 0 C above air temperature). This increased temperature can accelerate degradation of the polymer due to Arrhenius-type acceleration kinetics and also accelerate the evaporation, hydrolysis, and/or leaching of the additives.
  • a polymeric layer comprises a filler having high heat conductivity which is selected from the group consisting of metal carbonates, metal sulfates, metal oxides, metals, metal coated minerals and oxides, alumosilicates, and mineral fillers.
  • Adding mineral filler also lowers the CTE of the polymer. Whiskers and fibers are most effective in lowering CTE.
  • the introduction of mineral fillers to the polymeric layer also improves the processing quality of the layer.
  • the presence of filler in the melt lowers heat buildup by reducing torque during melt kneading, extruding and molding. This is especially important during melt kneading, which is a heat-generating process that can degrade the polymer.
  • filler when filler is introduced, less mechanical energy is required for melt kneading of a mass unit of compound relative to unfilled HDPE or MDPE, and thus the relative throughput per unit power increases and heat buildup in this compound along the extruder decreases.
  • a polymeric layer may further comprise barrier particles.
  • Barrier particles are inorganic particles having high barrier properties.
  • barrier properties refers to the ability of the inorganic particles to (1 ) reduce the rate of diffusion of additives from the polymeric layer into its surrounding environment; (2) reduce the rate of diffusion of hydrolyzing agents such as water, protons and hydroxyl ions from the surrounding environment into the polymeric layer; and/or (3) reduce the production / mobility of free radicals and/or ozone inside the polymeric layer.
  • the major cause of loss of additives during the lifetime of the polymeric strip is due to diffusion, washing, hydrolysis, or evaporation.
  • the barrier particles are nanoparticles.
  • the barrier particles are selected from the group consisting of clays, organo-modified clays, nanotubes, metallic flakes, ceramic flakes, metal coated ceramic flakes, and glass flakes.
  • the barrier particles are flakes which maximize surface area per unit mass.
  • the polymeric layer comprising barrier particles is characterized by slower rate of leaching, evaporation and hydrolysis of said additives, relative to layers without the barrier particles.
  • Barrier particles may be present in a loading of from about 0.01 to about 85 weight percent, by weight of the polymeric layer. In more specific embodiments, barrier particles have a loading of from about 0.1 to about 70 weight percent of the polymer layer.
  • the permeability of the polymeric layer to molecules having a molecular weight lower than about 1000 Daltons should be at least 10 percent lower compared to a polymeric strip of the same composition but without the barrier particles.
  • the permeability of the polymeric layer to molecules having a molecular weight lower than about 1000 Daltons should be at least 25 percent lower compared to a polymeric strip made from HDPE without the barrier particles.
  • each polymeric layer comprises a polymer.
  • the polymer is selected from HDPE and medium density polyethylene (MDPE).
  • MDPE medium density polyethylene
  • the polymer itself has improved UHH-resistant properties compared to virgin polyethylene.
  • Such polymers are selected from the group consisting of (i) ethylene-acrylic acid ester copolymers and terpolymers; (ii) ethylene- methacrylic acid ester copolymers and terpolymers; (iii) acrylic acid ester copolymers and terpolymers; (iv) aliphatic polyesters; (v) aliphatic polyamides; (vi) aliphatic polyurethanes; mixtures thereof; and mixtures thereof with at least one polyolefin.
  • each polymeric layer in a polymeric strip is made from the same polymer.
  • a polymeric layer may further comprise friction-enhancing integral structures.
  • the increased friction decreases movement of the polymeric strip relative to the GRM it supports.
  • These friction-enhancing structures are generally formed by embossing.
  • the structures may comprise a pattern selected from the group consisting of textured patterns, embossed patterns, holes, finger-like extensions, hair-like extensions, wave- like extensions, co-extruded lines, dots, mats, and combinations thereof.
  • the polymeric strip may have a total thickness of from about 0.1 mm to about 5 mm and a total width of from about 10 mm to about 5,000 mm.
  • the average concentration of HALS, organic UV absorbers, and inorganic UV absorbers in the outer polymeric layer(s) is from about 1.2 to about 10 times greater than the average concentration of HALS, organic UV absorbers, and inorganic UV absorbers throughout the entire strip (i.e., including the inner polymeric layer(s)).
  • the polymeric strip may be a single-layer or multi-layer strip.
  • the polymeric strip has at least one inner polymeric layer and least one outer polymeric layer.
  • the outer polymeric layer is exposed to direct sunlight, whereas the inner polymeric layer is not.
  • the polymeric strip has two outer polymeric layers.
  • Each layer may comprise UHH resistant polymers, additives, fillers, and/or barrier particles as described.
  • One specific embodiment is a single layer UHH-resistant polymeric strip.
  • the polymeric strip comprises a polymer, UV-absorbing particles, and HALS.
  • the polymer may be a polyolefin or UHH-resistant polymer and combinations thereof.
  • the polymeric strip may further comprise filler, pigments, dyes, and/or barrier particles to ensure a stable polymer under UHH conditions.
  • the polymeric strip has a vivid color. Even with multiple additives, the color of the polymeric strip is determined primarily by the pigments or dyes used to create the color.
  • the UHH-resistant polymeric strip is a multilayer strip and has at least one layer comprising up to 100% (w/w) MDPE or HDPE; up to 50% (w/w) linear low density polyethylene (LLDPE); up to 70% (w/w) filler; and 0.005 to 5% (w/w) additives selected from UV absorbers and HALS; and 0.005 to 50% (w/w) barrier particles.
  • the UHH-resistant polymeric strip is a multilayer strip and has at least one layer comprising up to 100% (w/w) MDPE or HDPE; up to 100% (w/w) ethylene-acrylic or methacrylic acid ester copolymer or terpolymer; up to 70% (w/w) filler; and 0.005 to 50% (w/w) additives selected from UV absorbers and HALS; and 0.005 to 50% (w/w) barrier particles.
  • the UHH-resistant polymeric strip is a multilayer strip and has at least one layer comprising a polymer, filler, and either a UV absorber or HALS.
  • the layer may further comprise 0.005 to 50% (w/w) barrier particles.
  • the layer provides at least 10% lower extraction, evaporation and/or hydrolysis rate of the UV absorber relative to a layer of HDPE comprising the same additive and having the same dimensions.
  • a method is providing for making the polymeric layer(s) and/or strip(s).
  • the method comprises a step of melt kneading at least one polymer with at least one additive in an extruder.
  • the extruder may be a multi-screw extruder, especially a twin- screw extruder.
  • the extruder is a co-rotating twin screw extruder, especially a co-rotating twin screw extruder characterized by an L/D ratio of about 20 to 50.
  • the extruder may be equipped with at least one side feeder, at least one atmospheric vent (for steam and air removal), and optionally a vacuum vent for degassing from volatile monomers and gaseous compounds. The mixture is then pumped downstream to form a film, strip, sheet, pellet, granule, powder or extruded article.
  • a master batch comprising a plurality of additives can be made, wherein a master batch refers to a concentrated dispersion and/or solution of all or part of the additives in a polymeric vehicle.
  • the master batch of additives is fed from a hopper to the extruder and melt kneaded together with the other ingredients of the composition.
  • the melt is then pumped downstream in the extruder into a dedicated mixing zone.
  • Filler can then be fed into the mixing zone from a top or side feeder. Entrapped air and adsorbed humidity are removed by atmospheric venting.
  • the mixture is further melt kneaded until most agglomerates are de-agglomerated and the filler is dispersed evenly in the mixture.
  • Entrapped volatiles and/or byproducts may be removed by optional vacuum venting. The result is then pumped through a die to form pellets or a strip or directly shaped into the final polymeric strip. Alternatively, the pellets can be re-melted in a second extruder or molding machine and then shaped.
  • friction-enhancing integral structures are formed in the polymeric layer(s) and/or strip(s).
  • the structures can be formed by embossing, punching, or extruding.
  • embossing is done by calendar embossing.
  • Prior art polymers were made in a reactor.
  • a reactor enables combination of few monomers in one backbone.
  • making polymer in a reactor is different from making polymer in an extruder.
  • a reactor enables manufacturing of UV-resistant polymers such as ethylene-acrylic acid ester copolymers and terpolymers; ethylene- methacrylic acid ester copolymers and terpolymers; acrylic acid ester copolymers and terpolymers.
  • a reactor does not enable manufacturing of a finely dispersed blend of strong, heat-resistant polymers and UHH-resistant polymers.
  • a reactor does not enable the dispersion of nanoparticles or fillers. In particular, it is difficult to evenly disperse filler in a reactor.
  • a three-dimensional cellular confinement system is formed from a plurality of UHH-resistant polymeric strips.
  • each strip appears to have a wave-like pattern with peaks and valleys.
  • the peaks of one strip are joined to the valleys of another strip so that a honeycomb-like pattern is formed.
  • the strips are stacked parallel to each other and interconnected by a plurality of discrete physical joints, the joints being spaced apart from each other by non-joined portions.
  • the joints may be formed by welding, bonding, sewing or any combination thereof.
  • the joints are welded by ultrasonic means.
  • the joints are welded by pressure-less ultrasonic means.
  • the distance between adjacent joints is from about 50 mm to about 1 ,200 mm.
  • the polymeric strips of the present disclosure have several desirable properties.
  • filler By incorporating filler, they have improved heat conductivity to avoid temperature buildup is avoided as well as improved weld quality.
  • the filler also lowers the CTE, so improved dimensional stability is obtained.
  • barrier particles By incorporating barrier particles, the leaching and/or evaporation of additives and the ingress of humidity, protons, or hydroxyl ions into the polymeric strip are reduced.
  • UV absorbing particles improved retention of UV resistance for period as long as 100 years is obtained.
  • the CCSs of the present disclosure have improved welding strength and durability.
  • the strength of the welds is at least 10% greater compared to a polymeric strip consisting of virgin HDPE and an equivalent loading of additives.
  • When welded strips are subjected to long term loading their failure rate is at least 10% lower compared to welded strips consisting of virgin HDPE and an equivalent loading of additives.
  • the welding cycle is at least 10% faster compared to a polymeric strip consisting of virgin HDPE and an equivalent loading of additives.
  • This improved weldability is mostly significant when ultrasonic welding is used because polyethylene is relatively difficult to weld by ultrasonic welding due to its low density, crystallinity, and low coefficient of friction.
  • welds It is important to protect welds from deterioration. They are relatively weak points in the CCS and as one weld fails, its load is transferred to other welds, increasing their load and increasing the probability that it will fail as well. Providing welds with increased weld strength prevents this from happening.
  • the CCSs of the present disclosure also have a lower rate of extraction, evaporation, or hydrolysis. They have a rate of extraction for HALS and/or organic UV absorbers at least 10% lower compared to an HDPE strip of the same thickness and having the same average concentration of HALS and UV absorbers throughout the HDPE strip (as compared to the layers of the CCS of the present disclosure) when extraction is performed at ambient temperature in water for a period of from about 6 to 24 months.
  • the residual content of the polymer can be determined by GC, HPLC or similar methods.
  • the CCSs also have at least 10% less degradation, as measured by the delta E color change and loss of elasticity (measured by elongation to break) compared to an HDPE strip of the same thickness and having the same average concentration of HALS and/or organic UV absorbers throughout the HDPE strip.
  • each mixture comprised 0.5% TiO 2 pigment (Kronos TM 2222 manufactured by Kronos) and 0.2 % PV Fast Brown HFR TM brown pigment (manufactured by Clariant).
  • the polymers, additives and pigments were fed to a main hopper of a co-rotating twin screw extruder running at 100- 400 RPM at barrel temperature of 180 to 240 Celsius.
  • the polymers were melted and the additives were dispersed by at least one kneading zone.
  • Filler was provided from a side feeder. Steam and gases were removed by an atmospheric vent and the product was pelletized by a strand pelletizer.
  • LLDPE resin - LL 3201 manufactured by Exxon Mobil.
  • Talc - lotalk TM superfine manufactured by Yokal.
  • HDPE resin - HDPE M 5010 manufactured by Dow. No UV absorber or HALS additives.
  • Example 2 Five mixtures, INV6 - INV10, and a reference mixture were made. Their composition is shown in TABLE 4. In addition, each mixture comprised 0.5% TiO 2 pigment (Kronos TM 2222 manufactured by Kronos) and 0.2 % PV Fast Brown HFR TM brown pigment (manufactured by Clariant). The polymers, additives and pigments were fed to a main hopper of a co-rotating twin screw extruder running at 100-400 RPM at barrel temperature of 260 to 285 Celsius. The polymers were melted and the additives were dispersed by at least one kneading zone. Filler was provided from a side feeder. Steam and gases were removed by an atmospheric vent and the product was pelletized by a strand pelletizer.
  • Talc - Iotalk TM superfine manufactured by Yokal.

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Abstract

L'invention concerne d'une manière générale un système de confinement cellulaire polymère que l'on peut remplir de terre, de béton, d'agrégat, de matières de terre, et analogues. Plus précisément, l'invention concerne un système de confinement cellulaire se caractérisant par une meilleure durabilité par rapport au dommage généré par la lumière UV, l'humidité, et les sols aggressifs ou par des combinaisons de ceux-ci.
EP07757728A 2007-03-01 2007-03-01 Système de confinement cellulaire multicouche résistant aux uv Withdrawn EP1986845A1 (fr)

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DE102009034362A1 (de) 2009-07-20 2011-01-27 Bayer Schering Pharma Aktiengesellschaft 17-Hydroxy-17-pentafluorethyl-estra-4,9(10)-dien-11-aryl-Derivate, Verfahren zu ihrer Herstellung und ihre Verwendung zur Behandlung von Krankheiten
US9745224B2 (en) 2011-10-07 2017-08-29 Boral Ip Holdings (Australia) Pty Limited Inorganic polymer/organic polymer composites and methods of making same
US8864901B2 (en) 2011-11-30 2014-10-21 Boral Ip Holdings (Australia) Pty Limited Calcium sulfoaluminate cement-containing inorganic polymer compositions and methods of making same
HRP20240270T1 (hr) * 2014-02-12 2024-05-10 Geotech Technologies Ltd. Geoćelija s poboljšanom otpornošću na sabijanje i deformaciju
CN103819798A (zh) * 2014-03-06 2014-05-28 四川雅豪房地产开发有限公司 一种单向拉伸土工格栅
CN104292643A (zh) * 2014-10-25 2015-01-21 安徽杰奥玛克合成材料科技有限公司 一种高耐热性土工格栅及其制备方法
CN110091554A (zh) * 2019-04-26 2019-08-06 中国科学院武汉岩土力学研究所 一种用于制作土工格室的复合材料及其制备方法
WO2022235862A1 (fr) * 2021-05-06 2022-11-10 Agru/America, Inc. Revêtement de frottement à étages multiples

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KR101153530B1 (ko) 2012-06-12
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CN101454150A (zh) 2009-06-10
AU2007347756B2 (en) 2009-01-29
WO2008105876A1 (fr) 2008-09-04
CA2641788C (fr) 2011-10-04
BRPI0714690A2 (pt) 2012-12-25
CA2641788A1 (fr) 2008-09-04
AU2007347756A1 (en) 2008-09-04

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