Patent Publication Number: US-9889966-B2

Title: Vented container for viscous liquids

Description:
FIELD OF THE INVENTION 
     The invention generally relates to vented containers, such as bottles, for the storage of viscous liquids, wherein the inner surface of a bottle improves the amount of material dispensed from the bottle. 
     BACKGROUND OF THE INVENTION 
     Squeeze containers are widely known and used for containing and dispensing a wide variety of viscous liquid products, such as body lotions. Squeeze containers typically have a flat base adapted for resting the container in an “upright” orientation that is substantially opposite of the dispensing orientation, in which the squeeze container is actually used. In the upright orientation the viscous product rests on the base within the container and air is trapped in the head space between the viscous product and the cap. To dispense the viscous product, the squeeze container is first inverted from its upright position wherein the viscous product and the air exchange places, such that the viscous product flows toward the opening of the container under the force of gravity, thereby displacing the air to a position between the viscous product and the base of the container. A user opens the cap and squeezes the container to reduce the interior volume of the package, thereby forcing the viscous product out of the cap. When finished dispensing, the user releases pressure and reorients the package in the upright position, such that the remaining viscous product flows back toward the base of the container and “replacement” air is permitted to vent through the discharge opening and into the container, thereby normalizing the atmospheric pressure in the container to permit the sidewall to recover its original shape. Thereafter, the cap is sealed until the next use. The fresh air is termed “replacement” air because it replaces or compensates for the displacement and lost volume of the viscous product. One disadvantage with such a dispensing container is that it is not continuously ready for immediate dispensing of the viscous product. 
     Squeeze containers, such as squeeze bottles, are becoming increasingly popular for dispensing viscous products, like liquid soap and shampoo. Squeeze bottles can be sleekly styled dispensing packages, which in certain styles do not include a flat base capable of supporting the bottle in an upright position; rather the bottle&#39;s cap provides a flat surface for support. A cap includes a flat end adapted for resting the bottle in an orientation that is substantially the same as its intended dispensing orientation. In its normal dispensing orientation, and with the cap in a sealed position, the viscous product rests next to the dispensing cap, and a head of air is trapped between the viscous product and the end wall of the bottle. One advantage of such a dispensing package is that the viscous product contained therein is generally immediately adjacent the dispensing opening, and is thus continuously ready for quick dispensing without having to invert the bottle. To dispense the viscous product, a user opens the cap and squeezes the bottle to reduce the interior volume, thereby forcing the viscous product out of the dispensing opening. When finished, the user releases the pressure, seals the cap, and rests the squeeze bottle on the flat base of the cap until the next use. 
     Unfortunately, however, the typical squeeze bottle does not readily permit venting of a fresh supply of replacement air in between uses or replacement air becomes trapped between the viscous product and the dispensing opening. This trapped air becomes a bubble making it more difficult for a user to dispense the product, as a user must first squeeze the bottle to expel the trapped air then squeeze again to actually dispense the product. 
     Further, due to the viscous nature of certain products, such as toothpastes, shampoos, comestibles, paints, lotions, cosmetics, or cleaning products, a residual amount may be left in the ends, along the sides, or edges of a bottle during normal use. In many cases, due to the particular shape of the bottle, a consumer is unable to dispense such residual product. This unused, residual product is often disposed of along with the bottle. 
     The bottle can be redesigned to improve product evacuation, but such redesigns can be costly and may not result in a significant decrease in the amount of residual product left in the bottle after normal use. For example, product release from a bottle can, in some cases, be improved by modifying the bottle shape or geometry to have shoulder portions that minimize the amount of residual product that remains in such areas. However, redesigning a bottle shape is costly, as new molds are typically required. 
     Other attempts to improve product release involve modifying the inner surface of the bottles. The entire bottle inner surface may be corona or plasma treated to modify the surface energy/wetting tension ability of the bottle material or a release coating may be applied to the inner surface of the bottle to provide a surface that the product may more easily release from. 
     Accordingly, there is a desire for a bottle that allows for improved product application while reducing the amount of unused residual product. 
     SUMMARY OF THE INVENTION 
     A container having a body having an end wall, side wall, and finished portion forming an inner cavity having an inner surface; a dispensing cap having a cap lid, a dispensing outlet and a vent opening; an outlet valve arrangement; and wherein the inner surface is modified to reduce adhesion between the inner surface and a viscous liquid. 
     A container having a body having an end wall, side wall, and finished portion forming an inner cavity having an inner surface; a dispensing cap having a cap lid, a dispensing outlet and air channel opening; an outlet valve having an outlet valve flap and a flexible outlet valve retainer ring having an outlet valve retainer ring opening; wherein the inner surface is modified to reduce adhesion between the inner surface and a viscous liquid. 
     A method of dispensing a viscous liquid comprising providing a container having a body having an end wall, side wall, and finished portion forming an inner cavity having an inner surface; a dispensing cap having a cap lid, a dispensing outlet and a vent opening; an outlet valve having an outlet valve flap and an outlet valve retainer ring having an outlet valve retainer ring opening; viscous liquid; wherein the inner surface is modified to reduce adhesion between the inner surface and a viscous liquid; applying pressure to the bottle to open the valve flap and dispense the viscous liquid; releasing the pressure and closing the valve flap; and drawing replacement air through the vent opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a bottle according to an embodiment of the present invention. 
         FIG. 2  is a partial longitudinal cross-sectional view of the bottle of  FIG. 1  taken substantially along line  2 - 2  thereof. 
         FIG. 3  is a close-up longitudinal cross-sectional view of a dispensing valved cap and vent according to  FIG. 1  taken substantially along line  2 - 2  thereof, but with the cap open. 
         FIG. 4  is an exploded view of a dispensing valved cap and vent according to an embodiment of the present invention. 
         FIG. 5A  is an exploded cross-sectional view of a dispensing valved cap and vent according to an embodiment of the present invention. 
         FIG. 5B  is a cross-sectional view of a dispensing valved cap according to an embodiment of the present invention. 
         FIG. 6A  is an exploded cross-sectional view of a dispensing valved cap and vent according to an embodiment of the present invention. 
         FIG. 6B  is a cross-sectional view of a dispensing valved cap according to an embodiment of the present invention. 
         FIG. 7  is a perspective view of a vent opening and vent membrane according to an embodiment of the present invention. 
         FIG. 8  is a perspective view of a vent opening and vent membrane shown in  FIG. 7  when open. 
         FIG. 9  is a sectional view of the vent opening and vent membrane shown in  FIG. 7  when open. 
         FIG. 10  is a perspective view of the vent opening and vent membrane shown in  FIG. 7  when closed. 
         FIG. 11  is a sectional view of the vent opening and vent membrane shown in  FIG. 7  when closed. 
         FIG. 12  is a schematic cross-sectional view a viscous liquid contacting an inner surface according to an embodiment of the present invention. 
         FIG. 13  is a schematic cross-sectional view of a viscous liquid that has impaled an inner surface according to an embodiment of the present invention. 
         FIG. 14  is a schematic cross-sectional view of a viscous liquid in contact with a liquid impregnated inner surface according to an embodiment of the present invention. 
         FIG. 15  is a schematic cross-sectional view of a viscous liquid in contacted with a liquid impregnated inner surface with excess impregnating liquid according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed to a bottle having a viscous liquid disposed therein. The bottle has a modified inner surface that reduces the amount of residual viscous liquid attached to the inner surface of the bottle. Such modifications may take the form of anti-adherence compositions that reduce the adherence of viscous liquids to the inner surface allowing for most of the viscous liquid to be expelled from the bottle. The anti-adherence compositions may be coated on the inner surface or incorporated in the bottle or both. Further in place of a normal flat surface the inner surface of the bottle may have three-dimensional structure, reducing the surface contact area between the viscous liquid and the inner surface. A bottle also includes a valve and one or more vents that allow for air intake to equalize pressure within the bottle after dispensing a viscous liquid. A vent is positioned below the fluid level, such as in the cap, and in proximity to the bottle wall. This positioning allows the air introduced by the vent to travel along the bottle inner surface to the head space. Such travel along the inner surface is possible due to the inner surface modifications. 
     For purposes herein, a “viscous” liquid, substance, or product generally refers to a material, in certain embodiments, having a viscosity greater than about 5,000 cp, greater than about 100,000 cp, or greater than about 200,000 cp. Viscosity is measured using a Brookfield viscometer with a spindle appropriate for the material at room temperatures; however, other methods and equipment may also be used to determine viscosity as needed. Examples of viscous products suitable for use in the bottles described herein, include but are not limited to, toothpaste, shampoo, comestibles, paints, coatings, dyes, cosmetics, lotions, pastes, ointments, pharmaceuticals, adhesives, and the like. As also used herein, “normal use” of a bottle means evacuation of the viscous product through the bottle opening without using a supplementary utensil, such as a knife or spoon, to scrape interior surfaces of the bottle to remove residual product. Normal use generally involves dispensing the viscous product from the bottle by pouring, squeezing, shaking, hitting, pounding, or any combination of such actions. 
       FIGS. 1 and 2  illustrate a container  10  embodiment of the present invention for dispensing a viscous liquid  62 . The container  10 , more specifically, a bottle  10  including a body  11  and a dispensing cap  14  attached thereto, wherein the dispensing cap  14  includes a flat surface  15  for resting the bottle  10  on a surface. The body is flexible to an extent that it may deform in response to pressure differences arising between the inside of said body and the ambient pressure. The body  11  may be composed of a light weight flexible resilient material, such as polypropylene (PP), low density polyethylene (LDPE), high density polyethylene (HDPE), polyethylene terepthalate (PET) or the like, and may be produced by any desired method including blow molding a preform, blow molding an extruded parison or the like. The material may be white, transparent, opaque transparent, translucent, or colored. The body  11  includes an end wall  16  and a sidewall  18  extending away from the end wall  16 , defining an inner cavity  17  for containing the viscous liquid  62  therein. As shown in  FIG. 2 , with such filling configuration, a head space  54  is formed between the viscous liquid  62  upper surface  25  and the end wall  16  of the body  11 . The headspace  54  is a portion of the inner cavity  17  that is generally free of or not filled with the viscous liquid  62 . As best shown in  FIG. 2 , the side wall  18  terminates in a finish portion  20  that includes a transverse end  22  defining an opening  24  into the inner cavity  17  of the body  11 . Each of the side wall  18 , end wall  16 , and finish portion  20  has an inner surface  38 ,  36 , and  40 , respectively. The finish portion  20  also includes an attachment portion  26 , which as shown in  FIG. 2  may be a snap bead, but which may be any attachment means known in the art, such as a threaded arrangement, welding, or gluing, for engaging the dispensing cap  14 . 
     It should be appreciated that the figures only schematically illustrate the body  11 , and the body  11  may be formed from a variety of different shapes, sizes, configurations, and materials. In one example, a suitable body has a height of about 18 cm, a width of about 3 cm to about 5 cm, and a depth of about 3 cm to about 5 cm. 
     In addition, while this embodiment is shown in a vertical position the invention also works when a bottle is in a horizontal position. Further, in certain embodiments bottles do not include a flat end wall capable of supporting the bottle in an upright position, which is known as a bottle. 
     As shown in  FIGS. 2, 3 and 4 , in certain embodiments, dispensing cap  14  is a tri-skirt design, which allows the outer profile of the dispensing cap  14  to blend with the outer profile of the body  11 . The dispensing cap  14  may be composed of any desired polymer or copolymer including PP, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene (PE) and the like, and may be produced by any desired process including injection molding or the like. The dispensing cap  14  includes a base wall  30  having a circumferentially continuous exterior skirt  32  and a circumferentially continuous interior skirt  34  extending from the base wall  30 . The skirts  32 ,  34  may include first and second radially inwardly extending helical thread segments or ridges  35  for engaging the corresponding external thread segments or ridges  26  of the body  11  so as to retain the dispensing cap  14  to the body  11 . The dispensing cap  14  further includes an annular skirt  41  extending away from the base wall  30 . A dispensing outlet  42  is provided in the base wall  30 . Seated within the dispensing outlet  42  and facing the base wall  30  is an outlet valve arrangement  90  comprising, in this embodiment, an outlet valve  92  having an outlet valve flap  93  and an outlet valve retainer ring  94 . 
     In certain embodiments, as shown in  FIGS. 5A, 5B, 6A and 6B  in an outlet valve flap  93  may be sectioned into two or more parts, such as the bisected flap  93  illustrated in  FIGS. 5A, 5B, 6A and 6B  which is hinged on both sides, allowing both parts of the valve flap to open and close from the midline of the outlet valve  92  rather than one side. One skilled in the art could also envision that an outlet valve flap could be sectioned in other ways, such as trisected. These may have an additional advantage of widening the product flowpath and/or reducing the force to dispense. 
     The outlet valve  92  is positioned between the annular skirt  41  and the outlet valve retainer ring  94 . The outlet valve retainer ring  94  rests on the face of the outlet valve  92  opposite the annular skirt  41 . The outlet valve  92  may be integral with or directly attached to the annular skirt  41 , for example, by the use of adhesive and/or the outlet valve  92  may be held in position by the outlet valve retainer ring  94 . The outlet valve retainer ring  94  may be interference fitted or snap-fit with the annular skirt seal  41  extending from the base wall  30 , the interior skirt  34 , or both and/or the outlet valve retainer ring  94  may be directly attached to the annular skirt  41  and/or interior skirt  34 , for example, by the use of adhesive. In certain embodiments, as shown in  FIGS. 2 and 3 , to provide additional support to the retainer ring  94  the inner surface of the interior skirt  34  may have a notch  43  to accept the outer edge of the retainer ring  94 . While a notch is illustrated in  FIGS. 2 and 3  any other mechanism that could provide support to the retainer ring could be used, for example a ridge extending for the surface of the interior skirt, tabs, or adhesive. In certain embodiments the outlet valve retainer ring  94  may be substantially flat as shown in  FIG. 4  or in certain other embodiments conical or funnel shaped as shown in  FIGS. 5A, 5B, 6A and 6B  to aid dispensing and minimize product residue. The outlet valve retainer ring opening  96  is smaller in diameter than the outlet valve flap  93 . The outlet valve retainer ring  94  serves to hold the outlet valve flap  93  in place and the smaller diameter of the outlet valve retainer ring opening  96  prevents the outlet valve flap  93  from moving inwards towards the inner cavity  17  of the bottle  10 . The inability of the outlet valve flap  93  to move inwards allows viscous liquid to exit the bottle and allows only a small portion of product to be pulled back towards the inside of the bottle when pressure on the bottle is released (this is generally positive for the user as it gives a neater cut-off), but prevents the intake of replacement air once the user is done squeezing, as the outlet valve flap  93  is prevented from moving upwards due to the outlet valve retainer ring  94 . Therefore to return the inner cavity  17  of the bottle  10  to an equalized pressure replacement air must enter through a vent opening  116 . 
       FIG. 7  is an enlarged view of a vent  100 . While  FIG. 7  illustrates a vent  100  comprising a flap type valve, other valves could be used, for example—duckbill valves, umbrella valves, minivalveballs, cross slit valves, and combination valves.  FIG. 7  shows an embodiment in which a rectangular thin film check valve membrane  115  is placed so as to cover the channel  116  with an openable side of the check valve membrane  115  proximal to the channel  116  and opening on the side closest to the interior skirt  34 . The thin film can be made from any desired polymer or copolymer film. The check valve membrane  115  can be fixed with a U-shaped adhesive bead  114  or heat sealed encircling the channel  116  except on one openable side  117 . The check valve membrane  115 , as shown in  FIG. 3 , should face the inner cavity  17  so that the replacement air is directed towards the interior skirt  34  and/or the inner surface of the finish portion  40  and side wall  38 . The check valve membrane  115  opens on only one side as shown in  FIG. 8  and  FIG. 9 , and the channel  116  is closed by the check valve membrane  115  as shown in  FIG. 10  and  FIG. 11 . When viscous liquid is dispensed through the dispensing outlet  42  or when in the resting position the membrane  115  is pressed against the outlet valve retainer ring  94  and therefore closes the channel  116 . 
     As illustrated in  FIG. 3 , dispensing cap  14  is shown in an open position with the cap lid  46  flexibly hinged to the base wall  30  at one side thereof by a hinge  48 , but displaced from the base wall  30 . As best shown in  FIG. 2 , the dispensing cap  14  includes an outlet seal  50  for sealing against the dispensing outlet  42  of the base wall  30  so as to seal the dispensing outlet  42  when the cap lid  46  is closed. The outlet seal  50  may be of any shape or size suitable to substantially seal the dispensing outlet  42 . In addition, in this embodiment, the cap lid  46  includes a vent plug  47  for sealing the vent opening  33  in the base wall  30  when the cap lid  46  is secured. The vent plug  47  may be of any shape or size suitable to substantially seal the vent opening  33 . The vent plug  47  may be made of the same material as the dispensing cap  14  or it may be made, at least in part, of different material, for example partially deformable material, such as thermoplastic Elastomers (TPE) such as block copolymers (styrenics, copolyesters, polyurethanes, polyamides) and TPE blends (thermoplastic polyolefins, thermoplastic vulcanizates) and alloys. Also, the back of the cap lid  46  partially defines the flat surface  15  of the dispensing cap  14  when closed. 
     Referring again to  FIG. 3 , one of ordinary skill in the art will recognize the advantageous functionality of the structure just previously described with respect to  FIG. 7 . With the present invention, it is now possible to vent replacement air into the inner cavity  17  of the bottle  10  while the bottle  10  is in its normal dispensing orientation as shown. 
     With reference to  FIGS. 2 and 3 , in the normal dispensing orientation, the viscous liquid  62  rests on the finish portion  20  of the body  11  and on the dispensing cap  14 , and a head of air is trapped in the head space  54  between the viscous liquid  62  and the end wall  16  of the body  11 . As mentioned previously, an advantage of such a bottle  10  is that the viscous liquid  62  contained therein is in close proximity to the discharge opening  42  and is thus continuously ready for quick dispensing without having to invert the bottle  10 . To dispense the viscous liquid  62 , a user applies pressure to the sidewall  18  of the bottle  10  to reduce the interior volume thereof, thereby compressing the head of air in the head space  54  to force the viscous liquid  62  out of the discharge opening  42 . After each dispensing cycle, the user releases pressure from the sidewall  18  of the bottle  10 , thereby partially enabling the resilient sidewall  18  to flex outwardly toward its original shape under the inherent resilient “memory” of the bottle  10 . This creates a vacuum in the head space  54  that tends to pull the outlet valve flap  93  upwards, sealing the retainer ring opening  96 , but leaving the vacuum in the inner cavity  17 , causing the check valve membrane  115  to lift off of the vent channel  116  and draw a fresh charge of replacement air through the vent channel  116 . The replacement air then travels along the interior skirt  34 , inner surface of the finish portion  40 , and the sidewall inner surface  38 , and into the head space  54  behind the viscous liquid  62 . As described below, the sidewall inner surface  38  is modified to allow the replacement air to travel along the sidewall inner surface  38 . Thereafter, the user can close the cap lid  46  of the dispensing cap  14 , and rest the bottle  10  on the flat base  15  of the dispensing cap  14  until the next use. In this way, the head space  54  is permitted to fill with replacement air after each dispensing cycle so that the inherent resiliency of the bottle sidewall  18  will return the bottle  10  to its freestanding original shape. 
     In certain embodiments, as shown in  FIGS. 6A and 6B , an outlet valve retainer ring  94  does not include a replacement air vent, only an air channel opening  98 . In this embodiment, the outlet valve retainer ring  94  wall is formed from materials and/or constructed such that it compresses and seals when the bottle is squeezed (such as a cup seal), as the viscous liquid presses against the outlet valve retainer ring bottom surface  95 ; and after dispensing the viscous liquid the outer rim  97  flexes inward toward cavity  17  when the bottle returns to its original shape after dispensing, as described previously the expanding volume of the bottle creates a vacuum, thereby allowing replacement air to enter the cap through the air channel opening  98  and bleed past the outlet valve retainer ring outer rim  97  and the interior skirt  34  anywhere along their mating surfaces. The replacement air then travels along the interior skirt  34  and inner surface of the finish portion  40 , and the sidewall inner surface  38 , and into the head space  54  behind the viscous liquid  62 . To provide flexibility the outlet valve retainer ring may be constructed in any manner, for example by having a funnel or conical shape and/or an outer rim, to provide the flexibility to move, for example by having an elastic modulus in the range of about 16,000 psi to about 75,000 psi or from about 20,000 psi to about 40,000 psi, as the viscous liquid is being dispensed and afterwards as pressure is released. For instance, in certain embodiments the outer rim  97  may have a functional thickness from about 0.025 mm to about 0.38 mm or from about 0.076 mm to about 0.25 mm. Further, the outlet valve retainer ring may be formed from any material that can provide the desired flexibility, such as flexible plastics, for example low-density polyethylene (LDPE), polytetrafluoroethylene (PTFE) or polypropylene. This embodiment has the additional advantage of allowing replacement air to travel along the bottle inner surface without the complexity and cost associated with a vent. 
     Referring to  FIG. 2 , a bottle having improved product release  10  is illustrated for holding and dispensing a viscous liquid  62 . Improved product release is provided by reducing the adhesion between the viscous liquid and the inner surface of the bottle. The reduction in adhesion can be delivered using one or a combination of modifications to the bottle inner surface, such as coating the inner surface with anti-adherence composition, incorporating an anti-adherence composition into the bottle, forming the bottle from a low surface energy material, or providing three dimensional structure to the inner surface, such as by imprinting or shaping the inner surface, or combinations thereof. 
     An anti-adherence composition can be a liquid, solid or both, in certain embodiments as shown in  FIGS. 2 and 3  when the anti-adherence composition is a liquid it can be applied as a coating  57  to the inner surface of a bottle  10 . In general the anti-adherence coating should be immiscible with the product. A coating  57  can be applied in effective amounts to inner surfaces  36 ,  38 ,  40  of the bottle  10  to maintain product stability and to provide increased viscous liquid evacuation. A coating  57  may also be applied to one or more of the retainer ring  94 , outlet valve  93 , annular skirt  41 , interior skirt  34 , or base wall  30 . In certain embodiments, the coating may be applied to a predetermined coverage area that is less than the entire inner surface area of the bottle  10 . As one of skill in the art would recognize, a variety of suitable anti-adherence coatings can be used that exhibit the general properties described above. Known anti-adherence materials that exhibit the requisite coating properties include, but are not limited to natural oils, silicone oils, and mineral oils. The natural oils are esters of glycerol and fatty acids; whereas, the mineral oils are hydrocarbon-based compounds and the silicone oils can be based on poly-organosiloxanes. 
     Examples of natural oils that are suitable in the present invention include, but are not limited to, a vegetable oil, such as olive oil, soybean oil, sunflower oil, canola oil and the like. In yet another form, the coating may include mixtures of soybean or canola oil combined with small amounts of lecithin (i.e., about 20 percent or less) and food grade alcohols (i.e., about 20 percent or less). Such alternative coatings are expected to provide similar results when applied to the bottle inner surface. 
     In the practice of the present invention, any relative amounts of bottle material and anti-adherence composition may be utilized that will provide the desired release property to the inner surface. In certain embodiments, the anti-adherence composition is provided to the bottle material in an effective amount to reduce residual viscous liquid remaining on an inner surface. The effective amount of anti-adherence composition will be selected upon consideration of the bottle material, the viscous liquid to be used therewith, economic factors, and engineering considerations. 
     In certain embodiments when an anti-adherence composition is incorporated into the body material, the body weight percent of anti-adherence composition, may generally comprise in the range of about 0.5 to about 20 weight percent anti-adherence composition, may comprise in the range of about 2 to about 20 weight percent anti-adherence composition, may comprise in the range of about 3 to about 15 weight percent anti-adherence composition, or may comprise in the range of about 3 to about 10 weight percent anti-adherence composition. The composition of the present invention may be formed by blending the anti-adherence composition with the plastic in molten form, or the anti-adherence composition may be compounded with the plastic. Examples of anti-adherence compositions that can be incorporated into the body material include ultra high molecular weight siloxane polymer, glycerol monostearate, erucamide. 
     In certain embodiments the bottles herein evacuate greater than 90 percent, greater than 95 percent, greater than 98 percent of the viscous liquid independent of bottle geometry. 
     In certain embodiments the coating composition may be uniformly applied to the predetermined coverage area in a thickness of about 0.003 inches or less. 
     As described previously the inner surface of a bottle may have three dimensional structure, for example  FIG. 12  is a schematic cross-sectional view of a contacting viscous liquid  202  in contact with a traditional non-wetting inner surface  204  (i.e., a gas impregnating surface), in accordance with one embodiment of the invention. The inner surface  204  includes a solid  206  having a surface texture defined by posts  208 . The regions between the posts  208  are occupied by a gas  210 , such as air. As depicted, while the contacting viscous liquid  202  is able to contact the tops of the posts  208 , a gas-liquid interface  212  prevents the viscous liquid  202  from wetting the entire inner surface  204 . 
     Referring to  FIG. 13 , in certain instances, the contacting viscous liquid  202  may displace the impregnating gas and become impaled within the posts  208  of the solid  206 . Impalement may occur, for example, when a liquid droplet impinges the inner surface  204  at high velocity. When impalement occurs, the gas occupying the regions between the posts  208  is replaced with the contacting viscous liquid  202 , either partially or completely, and the inner surface  204  may lose its non-wetting capabilities. 
     Referring to  FIG. 14 , in certain embodiments, a non-wetting, liquid-impregnated inner surface  220  is provided that includes a solid  222  having textures (e.g., posts  224 ) that are impregnated with an impregnating liquid  226 , rather than a gas. In the depicted embodiment, a contacting viscous liquid  228  in contact with the surface, rests on the posts  224  (or other texture) of the inner surface  220 . In the regions between the posts  224 , the contacting viscous liquid  228  is supported by the impregnating liquid  226 . In certain embodiments, the contacting viscous liquid  228  is immiscible with the impregnating liquid  226 . For example, the contacting viscous liquid  228  may be water and the impregnating liquid  226  may be oil. 
     Referring to  FIG. 15 , in certain embodiments, a non-wetting, liquid-impregnated inner surface  229  is provided that includes a solid  222  having textures (e.g., posts  224 ) that are impregnated with an impregnating liquid  226 , rather than a gas, and excess impregnating liquid  226  is applied such that the tops of the textured surface are substantially covered with the impregnating liquid  226 . In the depicted embodiment, a contacting viscous liquid  230  is in contact with the excess impregnating liquid  226 . In certain embodiments, the contacting viscous liquid  230  is immiscible with the impregnating liquid  226 . For example, the contacting viscous liquid  230  may be water and the impregnating liquid  226  may be oil. 
     The textures within the liquid-impregnated inner surface  220  and  229  are physical textures or surface roughness. The textures may be random, including fractal, or patterned. In certain embodiments, the textures are micro-scale or nano-scale features. For example, the textures may have a length scale L (e.g., an average pore diameter, or an average protrusion height) that is less than about 100 microns, less than about 10 microns, less than about 1 micron, less than about 0.1 microns, or less than about 0.01 microns. In certain embodiments, the texture includes posts  224  or other protrusions, such as spherical or hemispherical protrusions. Rounded protrusions may be used in certain embodiments to avoid sharp solid edges and minimize pinning of liquid edges. The texture may be introduced to the surface using any conventional method, including mechanical and/or chemical methods such as lithography, self-assembly, imprinting, and deposition, for example. 
     The impregnating liquid  226  may be any type of liquid that is capable of providing the desired non-wetting properties. For example, the impregnating liquid  226  may be oil-based or water-based (i.e., aqueous). In certain embodiments, the impregnating liquid  226  is an ionic liquid (e.g., BMI-IM). Other examples of possible impregnating liquids include hexadecane, vacuum pump oils (e.g., FOMBLIN (Registered trademark) 06/6, KRYTOX (Registered trademark) 1506) silicone oils (e.g., 10 cSt or 1000 cSt), fluorocarbons (e.g., perfluoro-tripentylamine, FC-70), shear-thinning fluids, shear-thickening fluids, liquid polymers, dissolved polymers, viscoelastic fluids, and/or liquid fluoroPOSS. In certain embodiments, the impregnating liquid is (or comprises) a liquid metal, a dielectric fluid, a ferro fluid, a magneto-rheological (MR) fluid, an electro-rheological (ER) fluid, an ionic fluid, a hydrocarbon liquid, and/or a fluorocarbon liquid. In one embodiment, the impregnating liquid  226  is made shear thickening with the introduction of nano particles. A shear-thickening impregnating liquid  226  may be desirable for preventing impalement and resisting impact from impinging liquids, for example. 
     The impregnating liquid  226  may be introduced to the inner surface  220  or  229  using any conventional technique for applying a liquid to a solid. In certain embodiments, a coating process, such as a dip coating, blade coating, or roller coating, is used to apply the impregnating liquid  226 . Alternatively, the impregnating liquid  226  may be introduced and/or replenished by liquid materials flowing past the inner surface  220  or  229  (e.g., in a pipeline). After the impregnating liquid  226  has been applied, capillary forces hold the liquid in place. Capillary forces scale roughly with the inverse of feature-to-feature distance or pore radius, and the features may be designed such that the liquid is held in place despite movement of the surface and despite movement of air or other fluids over the surface. Small features may also be useful to provide robustness and resistance to impact. 
     Compared to gas-impregnated surfaces, the liquid-impregnated surfaces described herein offer several advantages. For example, because liquids are incompressible over a large range of pressures, liquid-impregnated surfaces are generally more resistant to impalement. In certain embodiments, while nano-scale (e.g., less than one micron) textures may be necessary to avoid impalement with gas-impregnated surfaces, micro-scale (e.g., from 1 micron to about 100 microns) textures are sufficient for avoiding impalement with liquid-impregnated surface. As mentioned, micro-scale textures are much easier to manufacture and more practical than nano-scale textures. 
     Liquid-impregnated surfaces are also useful for reducing viscous drag between a solid surface and a flowing liquid. In general, the viscous drag or shear stress exerted by a liquid flowing over a solid surface is proportional to the viscosity of the liquid and the shear rate adjacent to the surface. A traditional assumption is that liquid molecules in contact with the solid surface stick to the surface, in a so-called “no-slip” boundary condition. While some slippage may occur between the liquid and the surface, the no-slip boundary condition is a useful assumption for most applications. 
     In certain embodiments, non-wetting surfaces, such as liquid-impregnated surfaces, are desirable as they induce a large amount of slip at the solid surface. For example, referring again to  FIGS. 12-15 , when a contacting liquid  202 ,  228 ,  230  is supported by an impregnating liquid  226  or a gas, the liquid-liquid or liquid-gas interface is free to flow or slip with respect to the underlying solid material. Drag reductions of as much as 40% may be achieved due to this slippage. As mentioned, however, gas-impregnated surfaces are susceptible to impalement. When impalement occurs with a gas-impregnated surface, the benefits of reduced drag reduction may be lost. 
     The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.” 
     Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern. 
     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.