TEXTURED POLYMER COMPOSITIONS

Abstract

The present invention relates to an article comprising a textured polymer surface for receiving a liquid, wherein the textured surface has an average surface roughness (Ra) in the range between 5 to 100 m.

Claims

1. An article of manufacture comprising a polymer/liquid composite, the polymer comprising a high density polyethylene (HDPE) polymer and (i) a roughening agent selected from mica, talcum, or silica, and/or (ii) a second polymer selected from polypropylene (PP), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polyolefin elastomer (POE), a second high density polyethylene (HDPE) or combination thereof, the polymer having a textured surface, wherein the textured surface has an average surface roughness (Ra) in the range between 5 to 100 m; and a liquid having drag reducing properties that is retained on the textured surface of the polymer forming a polymer/liquid composite.

2. The article according to claim 1, wherein the surface has projections with a height of 1 to 125 m and a base width of 5 to 640 m with a spacing of 0.1 to 500 m between projections.

3. The article according to claim 1, wherein the textured polymer comprises 80 to 99.9 weight percent of a HDPE polymer and/or 0.1 to 20 weight percent of a roughening agent.

4. The article according to claim 1, wherein the polymer comprises 0.1 to 10 weight percent mica.

5. The article according to claim 1, wherein the polymer comprises 0.1 to 10 weight percent silica.

6. The article according to claim 1, wherein the polymer comprises 0.1 to 20 weight percent talcum.

7. The article according to claim 1, wherein the polymer comprises 50 to 95 weight percent HDPE and 5 to 30 weight percent of the second polymer, and/or 0 to 2 weight percent of an additive.

8. The article according to claim 1, wherein the liquid is retained on the textured surface of the polymer more than 15% longer compared to pure HDPE.

9. The article according to claim 1, wherein the article is a container, tube, or pipe.

10. A method for producing an article of manufacture according to claim 1, comprising a textured polymer surface for receiving a liquid, the method comprising processing a polymer composition to form a textured polymer surface by (a) extruding or molding a polymer composition comprising a high density polyethylene (HDPE) and roughening agent selected from mica, talc, or silica to form an article having a textured polymer surface, the textured polymer surface having an average surface roughness (Ra) in the micron range and capable of receiving and retaining a liquid coating.

11. The method according to claim 10, further comprising coating the textured polymer surface with a liquid forming a coated textured polymer surface.

12. The method according to claim 10, wherein the resulting textured polymer surface has projections with a height of 1 to 125 m and a base width of 5 to 640 m, with a spacing of 0.1 to 500 m between projections or pores.

13. The method according to claim 10, further comprising inserting into the article a liquid, gel, paste, or semi-solid material.

14. The method according to claim 13 wherein the liquid, gel, paste, or semi-solid material which is inserted, is retained on the textured surface of the polymer more than 15% longer compared to pure HDPE.

15. The method according to claim 10, where in article contains a shampoo or cosmetic.

16. The article according to claim 1, wherein the surface has projections with a height of 1 to 125 m and a base width of 5 to 640 m with a spacing of 0.1 to 500 m between projections; wherein the textured polymer comprises 80 to 99.9 weight percent of a HDPE polymer and/or 0.1 to 20 weight percent of a roughening agent;

17. The article according to claim 16, wherein the polymer comprises 50 to 95 weight percent HDPE and 5 to 30 weight percent of the second polymer, and/or 0 to 2 weight percent of an additive.

18. The article according to claim 1, wherein the surface has projections with a height of 1 to 125 m and a base width of 5 to 640 m with a spacing of 0.1 to 500 m between projections; wherein the polymer comprises 0.1 to 10 weight percent mica, or 0.1 to 10 weight percent silica, or 0.1 to 20 weight percent talcum;

19. The article according to claim 18, wherein the polymer comprises 50 to 95 weight percent HDPE and 5 to 30 weight percent of the second polymer, and 0 to 2 weight percent of an additive.

Description

[0020] The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of the specification embodiments presented herein.

[0021] FIG. 1. An example of olive oil wetting behavior on the surface of selected textured polymers showing time and flow behavior (S=spreading and NS=non-spreading).

[0022] FIG. 2 A second example of olive oil wetting behavior on the surface of selected materials showing time and flow behavior (S=spreading and NS=non-spreading).

[0023] FIG. 3 A table illustrating laser profilometer roughness measurements of selected surfaces. Ra is the mean roughness or roughness average and Rq is the root mean square roughness.

[0024] FIG. 4 An example of a visualization of a surface measured using a laser profilometer. Right images being HDPE and Left images being HDPE+5% hydrocerol, which forms a foam or porous structure.

[0025] Certain embodiments are directed to polymer articles having at least one textured surface for receiving a liquid coating, the coated surface having lower drag or reduced friction. The textured polymer surface provides for retention of a liquid forming a thin film on the surface of the textured polymer (coating the surface). The textured polymer surfaces described herein are less expensive and easier to fabricate. In certain aspects the surface texture can be characterized using commercially available surface texture measurement devices, such as profilometers and the like.

[0026] The properties of the textured polymer surface can be designed based on the composition of the polymer, surface texture parameters, and/or character of the liquid coating. In certain aspects the polymer includes at least first polymer, such as HDPE. In other aspects the polymer is HDPE, LDPE, LLDPE, PP, POE, or a mixture thereof. In a further aspect a second polymer is selected as an additive, the second polymer or additive polymer can be selected from, but not limited to LDPE, LLDPE, PP, POE, or a mixture thereof. In certain aspects the second polymer is selected for properties that result in a textured polymer surface upon processing, for instance a foaming reaction. Articles of the invention have at least one textured polymeric surface that can be coated or contacted with a liquid that adheres to the textured surface.

[0027] As used herein the polymers include, but are not limited to:

[0028] HDPE is a polyethylene with a density (p) of at least () 940 kilograms per cubic meter (kg/m.sup.3).

[0029] LDPE is a polyethylene having a density of from about 910 to about 940 kg/m.sup.3 produced using radicals, for instance from oxygen or peroxide catalysts, at high pressure.

[0030] LLDPE (as distinguished from LDPE) is a homopolymer or copolymer of ethylene and with at least one -olefin containing from 3 to 20 carbon atoms (C.sub.3-20), made using transition metal catalysts and having a density from 915 to 930 kg/m.sup.3. Suitable -olefins are aliphatic -olefins containing from 3 to 20, preferably from 3 to 12, more preferably from 3 to 8 carbon atoms (C.sub.3-20, C.sub.3-12, C.sub.3-8). As used herein, subscripts indicate the number of, for example carbon (C) atoms contained in a monomer. Particularly suitable alpha-olefins include ethylene, propylene, butene-1, 4-methyl-1-pentene, hexene-1 or octene-1, or ethylene in combination with one or more of propylene, butene-1,4-methyl-1-pentene, hexene-1 and octene-1. Where LDPE has long chain branches as a result of the radical polymerization, the LLDPE is linear except for short chain branches that come from the co-monomers.

[0031] Polypropylene (PP) materials include (a) propylene homopolymers, (b) random and block copolymers of propylene and an olefin selected from ethylene, 1-olefins (-olefins) containing 4 to 10 carbon atoms (C.sub.4-10) and C.sub.4-10 dienes, and (c) random terpolymers of propylene and two monomers selected from ethylene and C.sub.4-10 -olefins. The C.sub.4-10 -olefins may be linear or branched, but are preferably linear.

[0032] -olefins are acyclic alkenes having a double bond connecting the first and the second carbon atom in the carbon chain. Examples of -olefins are ethylene, propylene, 1-butene, 1-methyl-4-pentene, 1-hexene, and 1-octene.

[0033] Polyolefin elastomers (POEs) are copolymers of ethylene and another alpha-olefin such as butene or octene. POEs have both thermoplastic and elastomeric properties, which can be processed by common processing methods for thermoplastic materials and have a density of less than 900 kg/m.sup.3.

[0034] A polymer surface can be textured by providing reaction materials, processing conditions, or post-polymerization treatments to form a surface texture comprising (a) projections, (b) open pores, or (c) projections and open pores. The polymerization reactions can be performed at a temperature of 5 to 100 C., including all values and ranges there between. Furthermore the polymerization reactions can be performed at a pressure of 0.1 to 10 MPa, including all values and ranges there between.

[0035] In one aspect, the invention is directed to an article comprising a liquid coated polymer surface, the polymer surface having a texture or roughness for receiving and retaining a liquid. The liquid can be retained between surface features, within surface features, or between and within surface features. The texture of the surface is such that the liquid is contained or maintained in or on the surface independent of the orientation of the surface (0 to 360 degrees relative to horizontal).

[0036] In certain aspects the surface texture is at least in part provided by additives (roughening agents). In certain aspects the additive(s) are incorporated in the polymer forming projections or pores/cavities in a polymer surface. A roughening agent imparts a roughness to the surface by providing a material that causes protrusions from the surface forming peaks and valleys. Other roughening agents are agents can be foamed, removed, modified, or partially removed during or after processing to form projections and/or pores in or on the surface of the polymer. The amount of surface texture is controlled by the amount of additive in, on, or in and on the polymer support during the manufacturing process. The amount of additive included in the polymer support can depend on the properties needed for a certain target in any given application.

[0037] In certain aspects, the target can be a substance to be contained or transported within or placed in contact with a container (e.g., a bottle or jar) or a conveyance device (e.g., pipeline) that has a surface that is a coated textured polymer surface as described herein. The amount and type of additive should be selected to provide a surface texture that yields the appropriate surface with its attendant properties.

[0038] The additive can be present in an amount of about 0.1 to 50 wt %, 0.1 to 20 wt %, 0.1 to 10 wt % of the polymer composition. Depending on various factors, such as the desired surface texture, the additive material can be present in an amount between about 5 to 20 wt % of the polymer composition. The additive can form projections and/or pores having variety of shapes, that include, but are not limited to rounded, columnar, pyramidal, and/or random geometry (irregular) protrusions, and/or pores (e.g., cavities) that provide a surface texture. The spacing of projections or pores can be determined by measuring the shortest distance between two adjacent projections or the edges of adjacent pores. The projections or pores can be dispersed on the surface forming an average spacing between projections and/or pores of about 0.01 to 500 microns, including all values and ranges there between. In a further aspect the projections can have an average height of about 1 to 125 microns relative the plane of the surface. In certain aspect the pores can have an average depth of about 1 to 125 microns relative the plane of the surface.

[0039] In certain embodiments the additive is a roughening agent. The roughing agent is preferably an inorganic material. In certain aspects the roughening agent is melt compoundable with a selected polymer. The roughing agent can include inorganic materials, alone or in combination. For example zeolites, glass, talc, mica, clay, silica, sodium, calcium, alumino silicates, calcium carbonates, aluminum silicates, sodium silicates, magnesium silicates, calcium silicates, and silicon dioxides. In certain aspects mica, talc, clay, or silica is used as the roughening agent. The roughening agent can be a regular or irregular particle having an average dimension that can be the diameter for approximately spherical particles or length for approximately rod-shaped particles. For irregular particles the average dimension can be the largest dimension presented by an irregular shape. In certain aspects the roughening agent is in particle form. In a further aspect the particles have an average dimension of about 5 to 640 0.1 to 500 microns, including all values and ranges there between.

[0040] In certain aspects a textured polymer surface can have a plurality of pores, cavities, interconnected pores, and/or interconnected cavities. The plurality of pores, cavities, interconnected pores, and/or interconnected cavities can be formed by using a conditioning agent as an additive. A conditioning agent is used to form the texture on the surface, but is not necessarily present in the final textured product. For example, a conditioning agent can be used to form pores or wells that can be filled by a liquid, the pores can formed by embedding salts or other dissolvable or degradable materials in the polymer or polymer surface and removing the materials during or after polymerization. The conditioning agent can be removed by using a solvent, heat, or electromagnetic radiation to dissolve or degrade the conditioning agent or a portion of the polymer that was in contact with the conditioning agent or not in contact with the conditioning agent. Another example of a conditioning agent is a second polymer that is immiscible with first polymer that is used as the base material. In certain aspects the immiscible second polymer forms pores or cavities in the polymer surface during processing. In certain embodiments the pores or cavities have average relief depths of about 1 to 20 m, surface cavity diameters from about 1 to 10 m, and/or porosity densities in the range of about 4 to 120 pores per m.sup.2.

[0041] In another embodiment the pores or cavities can be formed by foaming or pitting the surface of polymer base or support. The surface of the polymer base or support can be foamed using physical, chemical, or physical and chemical methods. Physical foaming agents include but are not limited to organic materials as hydrocarbons or chlorinated hydrocarbons, or inorganic materials as nitrogen or carbon dioxide or combinations of both. Chemical foaming agents can be of the exothermic or endothermic types, such as carbon dioxide with an endothermic chemical blowing agent. Physical pitting processes include sand blasting. In certain aspects the foaming process is performed at about 40 to 260 C. The foaming procedure can form the pores or cavities as described above. In certain embodiment the foam has an open cell structure, limited cell size, and limited thickness in relation to the open cell structure. Polymers with a low melt strength behavior are suitable to produce open cell structures, e.g. high MFI HDPE; PP; or LL/MDPE.

[0042] The surface texture provides a geometry that provides for interaction with a liquid that can fill the space between or in the textural features and coat the surface with a layer (thin film) of liquid of about 1 to 5 nm in thickness above the plane of the polymer surface. In certain embodiments, the liquid has a receding contact angle of 0 such that the liquid forms a stable thin film on the surface.

[0043] The liquid can be introduced to the textured polymer surface using conventional techniques 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 a liquid. After the liquid 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. In certain aspects, the liquid has a viscosity at room temperature of at least, at most, or about 50 to 5000 cP (or cSt). In certain embodiments, the liquid can be any type of liquid that is capable of providing the desired properties. For example, the liquid can be an oil-based or water-based liquid. In certain aspects, the liquid is an ionic liquid. Other liquids include hexadecane, vacuum pump oils, silicone oils, fluorocarbons, liquid polymers, dissolved polymers, and viscoelastic fluids. In certain embodiments, the liquid includes 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.

[0044] Certain embodiments are directed to articles of manufacture having a wall or a surface that is a textured polymer for receiving a coating. In one aspect the wall or support is monolithic or a single layer having a textured surface. In other aspects the surface is an inner surface of a pipe, tube, syringe, bottle, jar, or other container or fluid transfer device. An article comprising a textured polymer surface includes a textured polymer surface coated with a liquid, wherein the liquid forms a thin film, i.e., a coated textured polymer surface. The thin film modulates interaction between the polymer article and a target fluid or material. In certain aspects the target material is a liquid, lotion, gel, paste, or the like. In certain aspects the target material is a foodstuff (e.g., condiment, jelly, or the like) or a cosmetic (e.g., a shampoo or other cosmetic liquid or gel).

[0045] In certain aspects a polymer composition described herein can have sufficient environmental stress crack resistance (ESCR). ESCR testing can be performed using, for example, ASTM D1693, condition B, with 10% igepal. In some aspects, the polymers described herein can have an ESCR (using 10% igepal) of greater than or equal to about 600 to 2500 hours. The ESCR test is typically stopped after a certain number of hours is reached, and given the long duration of the test, the upper limit of ESCR (in hours) is generally not determined.

[0046] A coated textured polymer surface can be used to reduce viscous drag between a solid surface and a flowing target. In general, the viscous drag or shear stress exerted by a target liquid flowing over a solid surface is proportional to the viscosity of the target liquid and the shear rate adjacent to the surface.

[0047] The polymer having a textured surface for receiving a liquid can be used in producing an article of manufacture that includes a coated inner textured polymer surface of the current invention. An article of the current invention can be produced by various processes used in thermoplastics manufacture, including blow molding. Blow molding is a manufacturing process by which hollow plastic parts are formed. In general, there are three main types of blow molding: extrusion blow molding, injection blow molding, and injection stretch blow molding. The blow molding process begins with melting down the plastic and forming it into a parison or in the case of injection and injection stretch blow molding (ISB) a preform. The parison is a tube-like piece of plastic with a hole in one end through which compressed air can pass. The parison is then clamped into a mold and air is blown into it. The air pressure then pushes the plastic out to match the mold. Once the plastic has cooled and hardened the mold opens up and the part is ejected. In certain embodiments of the current invention at least one surface of the part is coated with a liquid or is further process and then coated with a liquid to form a coated textured polymer surface.

[0048] The following examples as well as the figures are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples or figures represent techniques discovered by the inventors to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

EXAMPLE 1

Production and Testing of Materials

[0049] Test films were or can be prepared by using a micro compounding line with a cast film die to prepare cast film. Approximately 10 gram of polymer were used to produce 5 meter cast film. A melt web is cooled by an air knife (a simulation of blow molding process by blowing air to the melt).

[0050] In an alternative method, micro blown film lines were produced using approximately 1 kg of sample. A micro blown film line was used with a low BUR (1.5 to 2) to produce a pipe shape product with a thickness of a least 200 m. Another option is to connect a cast film die to the compounder to produce cast film having a thickness target of 300 m. In these processes a melt web is cooled by an air knife.

[0051] Production tests are designed and performed. Various compounds were tested in a primary texture screen. After selection, the selected polymer formulations are further screened for functional properties. In one aspect the selected polymer formulation can be tested using a blow molding line to produce small bottles.

[0052] The surface roughness of the test materials can be measured by a laser profilometer to create 3D pictures. In certain aspects the laser profile meter can be set to at least 0.5 m.

[0053] In certain instances the smallest bottle produced is about 110 ml, using 5.5 kg/hour mono-layer with 20 g at 14 sec cycle time. An additional amount of resin (15-20 kg) may be needed for purging to get a clean layer.

[0054] Processing of tapes can be performed, for example, with the following setup:

[0055] (i) 11 mm twin screw extruder with a L/D of 40; (ii) volumetric feeders to add base material and the additives, (iii) cast film die with adjustable slit, (iv) air knife to cooldown the extruded melt by blowing air to the melt, (v) chill roll with air pipe for additional cooling of the melt, (vi) nipp rolls module to setup the thickness of the tape, and (vii) winding module to wind up the produced tape.

EXAMPLE 2

Olive Oil Wetting Behavior

[0056] The purpose of the olive oil wetting studies is to determine the flow time and behavior of a droplet of olive oil that moves from point A to point B under an angle of 33. The flow time and behavior of the droplet (spreading or non-spreading) was determined. An increasing surface roughness should result in an increase in the flow time and the oil will spread over the surface.

[0057] A sample is fixed with double sided tape to a flat surface. Using a dispenser, a droplet of olive oil is placed on the surface. A video camera registers the flow behavior and movement of the droplet. Results from a number of these studies are presented in FIG. 1 and FIG. 2. Eighty percent of the tested samples have a higher flow time when compared to a reference HDPE. The flow time of samples containing fillers (mica/talcum) or cell structures (foam) are significantly higher than virgin samples. Samples with cell structures produce a surface with the highest flow time, but also absorb the oil (its spreading out in the surface). Compounds of HDPE with other type of polymers, such as HDPE of varying density, PP, and POE produce a surface that decreases the roughness because the flow time is faster compared to the reference HDPE. Roughness measures are provided in FIG. 3. An example of a visualization of the roughness measurement is provided in FIG. 4.