Patent Description:
In commercial container filling or packaging operations, the containers typically are moved by a conveying system at very high rates of speed. Typically, a concentrated lubricant is diluted with water to form an aqueous dilute lubricant solution (i.e., dilution ratios of <NUM>:<NUM> to <NUM>:<NUM>), and copious amounts of aqueous dilute lubricant solutions are typically applied to the conveyor or containers using spray or pumping equipment. These lubricant solutions permit high-speed operation of the conveyor and limit marring of the containers or labels, but also have some disadvantages. First, dilute aqueous lubricants typically require use of large amounts of water on the conveying line, which must then be disposed of or recycled, and which causes an unduly wet environment near the conveyor line. Second, some aqueous lubricants can promote the growth of microbes. Third, by requiring dilution of the concentrated lubricant dilution errors can occur, leading to variations and errors in concentration of the aqueous dilute lubricant solution. Finally, by requiring water from the plant, variations in the water can have negative side effects on the dilute lubrication solution. For example, alkalinity in the water can lead to environmental stress cracking in PET bottles.

When an aqueous dilute lubricant solution is used, it is typically applied at least half of the time the conveyor is running, and usually it is applied continuously. By running the aqueous dilute lubricant solution continuously, more lubricant is used than is necessary, and the lubricant concentrate drums have to be switched out more often than necessary.

"Dry lubes" have been described in the past as a solution to the disadvantages of dilute aqueous lubricants. A "dry lube" historically has referred to a lubricant composition with less than <NUM>% water that was applied to a container or conveyor without dilution. However, this application typically required special dispensing equipment and nozzles and energized nozzles in particular. Energized nozzles refer to nozzles where the lubricant stream is broken into a spray of fine droplets by the use of energy, which may include high pressures, compressed air, or sonication to deliver the lubricant. Silicone materials have been the most popular "dry lube". However, silicone is primarily effective at lubricating plastics such as PET bottles, and has been observed to be less effective at lubricating on glass or metal containers, particularly on a metal surface. If a plant is running more than one type of container on a line, the conveyor lubricant will have to be switched before the new type of container can be run. Alternatively, if a plant is running different types of containers on different lines, the plant will have to stock more than one type of conveyor lubricant. Both scenarios are time consuming and inefficient for the plant.

It is against this background that the present invention has been made.

The present invention provides a method for lubricating the passage of a container along a conveyor, comprising applying a lubricant composition to at least a portion of the container-contacting surface of the conveyor or to at least a portion of the conveyor-contacting surface of the container, the lubricant composition comprising:.

according to claim <NUM>. Preferred embodiments of the method are lined out in the annexed dependent claims.

The present invention is generally directed to a silicone lubricant having greater than <NUM>% water.

In a preferred method the present invention is directed to the use of a silicone lubricant having greater than <NUM>% water that is not diluted prior to applying it to a conveyor or container surface. In a further embodiment, the present invention is directed to a method of applying an undiluted lubricant intermittently.

The present invention provides several advantages over the prior art. First, by including water in the concentrate composition, the problems associated with dilute lubricants can be avoided. For example, the composition can be applied undiluted with standard application equipment (i.e. non-energized nozzles). By including some water, the composition can be applied "neat" or undiluted upon application resulting in drier lubrication of the conveyors and containers, a cleaner and drier conveyor line and working area, and reduced lubricant usage, thereby reducing waste, cleanup and disposal problems. Further, by adding water to the composition and not requiring dilution upon application, dilution problems are avoided along with problems created by the water (i.e. microorganisms and environmental stress cracking). Intermittent application of the lubricant composition also has the advantages of reduced lubricant usage and the resulting cost savings, and decreasing the frequency that the lubricant containers have to be switched.

Finally, the present invention has the ability to provide lubrication to a variety of container and conveyor materials, giving a plant the option to run one lubricant on several lines.

Weight percent, percent by weight, % by weight, wt %, and the like are synonyms that refer to the concentration of a substance as the weight of that substance divided by the weight of the composition and multiplied by <NUM>.

The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. <NUM> to <NUM> includes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>).

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a composition containing "a compound" includes a mixture of two or more compounds.

As previously discussed, the present invention is generally directed to a silicone lubricant having greater than <NUM>% water. The invention provides a lubricant coating that reduces the coefficient of friction of coated conveyor parts and containers and thereby facilitates movement of containers along a conveyor line. The present invention provides a method for lubricating the passage of a container along a conveyor comprising applying a mixture of a water-miscible silicone material and a water-miscible lubricant to at least a portion of the container contacting surface of the conveyor or to at least a portion of the conveyor contacting surface of the container according to claim <NUM>.

In a preferred embodiment, the present invention is directed to a method using silicone lubricant having greater than <NUM>% water that is not diluted prior to applying it to a conveyor or container surface. In a further preferred embodiment, the present invention is directed to a method of applying an undiluted lubricant intermittently. In a still further preferred embodiment, the present invention is directed to a method using a "universal" lubricant that may be used with a variety of container and conveyor materials. The composition preferably can be applied while the conveyor is at rest or while it is moving, e.g., at the conveyor's normal operating speed. Preferably the lubricant coating is water-based cleaning agent-removable, that is, it preferably is sufficiently soluble or dispersible in water so that the coating can be removed from the container or conveyor using conventional aqueous cleaners, without the need for high pressure, mechanical abrasion or the use of aggressive cleaning chemicals.

The silicone material and hydrophilic lubricant are "water-miscible", that is, they are sufficiently water-soluble or water-dispersible so that when added to water at the desired use level they form a stable solution, emulsion or suspension. The desired use level will vary according to the particular conveyor or container application, and according to the type of silicone and hydrophilic lubricant employed.

A variety of water-miscible silicone materials can be employed in the lubricant compositions used in the method of the present invention, including silicone emulsions (such as emulsions formed from methyl(dimethyl), higher alkyl and aryl silicones; and functionalized silicones such as chlorosilanes; amino-, methoxy-, epoxy- and vinyl-substituted siloxanes; and silanols). Suitable silicone emulsions include E2175 high viscosity polydimethylsiloxane (a <NUM>% siloxane emulsion commercially available from Lambent Technologies, Inc. ), E2140 polydimethylsiloxane (a <NUM>% siloxane emulsion commercially available from Lambent Technologies, Inc. ), E21456 FG food grade intermediate viscosity polydimethylsiloxane (a <NUM>% siloxane emulsion commercially available from Lambent Technologies, Inc. ), HV490 high molecular weight hydroxy-terminated dimethyl silicone (an anionic <NUM>-<NUM>% siloxane emulsion commercially available from Dow Coming Corporation), SM2135 polydimethylsiloxane (a nonionic <NUM>% siloxane emulsion commercially available from GE Silicones) and SM2167 polydimethylsiloxane (a cationic <NUM>% siloxane emulsion commercially available from GE Silicones). Other water-miscible silicone materials include finely divided silicone powders such as the TOSPEARL™ series (commercially available from Toshiba Silicone Co. ); and silicone surfactants such as SWP30 anionic silicone surfactant, WAXWS-P nonionic silicone surfactant, QUATQ-<NUM> cationic silicone surfactant and <NUM> specialty silicone surfactant (all commercially available from Lambent Technologies, Inc. Preferred silicone emulsions typically contain from about <NUM> wt. % to about <NUM> wt. Non-water-miscible silicone materials (e.g., non-water-soluble silicone fluids and non-water-dispersible silicone powders) can also be employed in the lubricant if combined with a suitable emulsifier (e.g., nonionic, anionic or cationic emulsifiers). For applications involving plastic containers (e.g., PET beverage bottles), care should be taken to avoid the use of emulsifiers or other surfactants that promote environmental stress cracking in plastic containers.

Polydimethylsiloxane emulsions are preferred silicone materials.

According to the present invention the water-miscible lubricant is a water-miscible fatty acid derivative, wherein the fatty acid comprises oleic acid, tall oil, a C<NUM>-C<NUM> fatty acid, and mixtures thereof, that is employed in the lubricant compositions used in the method of the present invention, including hydroxy-containing compounds such as sorbitan esters (e.g., TWEEN™ series <NUM>, <NUM>, <NUM>, <NUM> and <NUM> polyoxyethylene sorbitan monooleates and SPAN™ series <NUM>, <NUM>, <NUM> and <NUM> sorbitan esters, commercially available from ICI Surfactants), which hydroxy-containing compounds include a fatty acid moiety. Suitable water-miscible lubricants include fatty acid derivatives. Partial esters or ethoxylates of the above fatty acids can also be employed. For applications involving plastic containers, care should be taken to avoid the use of water-miscible lubricants that might promote environmental stress cracking in plastic containers.

Preferred amounts for the silicone material, hydrophilic lubricant and water or hydrophilic diluent are about <NUM> to about <NUM> wt. % of the silicone material (exclusive of any water or other hydrophilic diluent that may be present if the silicone material is, for example, a silicone emulsion), about <NUM> to about <NUM> wt. % of the hydrophilic lubricant, and about <NUM> to about <NUM> wt. % of water or hydrophilic diluent. More preferably, the lubricant composition used in the method of the present invention contains about <NUM> to about <NUM> wt. % of the silicone material, about <NUM> to about <NUM> wt. % of the hydrophilic lubricant, and about <NUM> to about <NUM> wt. % of water or hydrophilic diluent. Most preferably, the lubricant composition used in the method of the present invention contains about <NUM> to about <NUM> wt. % of the silicone material, about <NUM> to about <NUM> wt. % of the hydrophilic lubricant, and about <NUM> to about <NUM> wt. % of water or hydrophilic diluent.

The lubricant compositions used in the method of the present invention can contain additional components if desired. For example, the compositions can contain adjuvants such as conventional waterborne conveyor lubricants (e.g., fatty acid lubricants), antimicrobial agents, colorants, foam inhibitors or foam generators, cracking inhibitors (e.g., PET stress cracking inhibitors), viscosity modifiers, film forming materials, surfactants, antioxidants or antistatic agents. The amounts and types of such additional components will be apparent to those skilled in the art.

For applications involving plastic containers, the lubricant compositions used in the method of the present invention preferably have a total alkalinity equivalent to less than about <NUM> ppm CaCO<NUM>, more preferably less than about <NUM> ppm CaCO<NUM>, and most preferably less than about <NUM> ppm CaCO<NUM>, as measured in accordance with <NPL>.

A variety of kinds of conveyors and conveyor parts can be coated with the lubricant composition. Parts of the conveyor that support or guide or move the containers and thus are preferably coated with the lubricant composition include belts, chains, gates, chutes, sensors, and ramps having surfaces made of fabrics, metals, plastics, composites, or combinations of these materials.

The lubricant composition used in the method of the present invention can also be applied to a wide variety of containers including beverage containers; food containers; household or commercial cleaning product containers; and containers for oils, antifreeze or other industrial fluids. The containers can be made of a wide variety of materials including glasses; plastics (e.g., polyolefins such as polyethylene and polypropylene; polystyrenes; polyesters such as PET and polyethylene naphthalate (PEN); polyamides, polycarbonates; and mixtures or copolymers thereof); metals (e.g., aluminum, tin or steel); papers (e.g., untreated, treated, waxed or other coated papers); ceramics; and laminates or composites of two or more of these materials (e.g., laminates of PET, PEN or mixtures thereof with another plastic material). The containers can have a variety of sizes and forms, including cartons (e.g., waxed cartons or TETRAPACK™ boxes), cans, bottles and the like. Although any desired portion of the container can be coated with the lubricant composition, the lubricant composition preferably is applied only to parts of the container that will come into contact with the conveyor or with other containers. Preferably, the lubricant composition is not applied to portions of thermoplastic containers that are prone to stress cracking. In a preferred embodiment of the invention, the lubricant composition is applied to the crystalline foot portion of a blow-molded, footed PET container (or to one or more portions of a conveyor that will contact such foot portion) without applying significant quantities of lubricant composition to the amorphous center base portion of the container. Also, the lubricant composition preferably is not applied to portions of a container that might later be gripped by a user holding the container, or, if so applied, is preferably removed from such portion prior to shipment and sale of the container. For some such applications the lubricant composition preferably is applied to the conveyor rather than to the container, in order to limit the extent to which the container might later become slippery in actual use.

The lubricant composition can be a liquid or semi-solid at the time of application. Preferably the lubricant composition is a liquid having a viscosity that will permit it to be pumped and readily applied to a conveyor or containers, and that will facilitate rapid film formation whether or not the conveyor is in motion. The lubricant composition can be formulated so that it exhibits shear thinning or other pseudo-plastic behavior, manifested by a higher viscosity (e.g., non-dripping behavior) when at rest, and a much lower viscosity when subjected to shear stresses such as those provided by pumping, spraying or brushing the lubricant composition. This behavior can be brought about by, for example, including appropriate types and amounts of thixotropic fillers (e.g., treated or untreated fumed silicas) or other rheology modifiers in the lubricant composition.

The lubricant coating can be applied in a constant or intermittent fashion. Preferably, the lubricant coating is applied in an intermittent fashion in order to minimize the amount of applied lubricant composition. It has been discovered that the present invention may be applied intermittently and maintain a low coefficient of friction in between applications, or avoid a condition known as "drying". Specifically, the present invention may be applied for a period of time and then not applied for at least <NUM> minutes, at least <NUM> minutes, or at least <NUM> minutes or longer. The application period may be long enough to spread the composition over the conveyor belt (i.e. one revolution of the conveyor belt). During the application period, the actual application may be continuous, i.e. lubricant is applied to the entire conveyor, or intermittent, i.e. lubricant is applied in bands and the containers spread the lubricant around. The lubricant is preferably applied to the conveyor surface at a location that is not populated by packages or containers. For example, it is preferable to apply the lubricant spray upstream of the package or container flow or on the inverted conveyor surface moving underneath and upstream of the container or package.

In preferred embodiments, the ratio of application time to non-application time may be <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, and <NUM>:<NUM> where the lubricant maintains a low coefficient of friction in between lubricant applications.

In preferred embodiments, the lubricant maintains a coefficient of friction below about <NUM>, below about <NUM>, and below about <NUM>.

In preferred embodiments, a feedback loop may be used to determine when the coefficient of friction reaches an unacceptably high level. The feedback loop may trigger the lubricant composition to turn on for a period of time and then optionally turn the lubricant composition off when the coefficient of friction returns to an acceptable level.

The lubricant coating thickness preferably is maintained generally at the interface at at least about <NUM>, more preferably about <NUM> to about <NUM>, and most preferably about <NUM> to about <NUM>.

Application of the lubricant composition can be carried out using any suitable technique including spraying, wiping, brushing, drip coating, roll coating, and other methods for application of a thin film.

The invention can be better understood by reviewing the following examples. The examples are for illustration purposes only, and do not limit the scope of the invention.

Some of the following examples used a Slider Lubricity Test. The Slider Lubricity Test was done by measuring the drag force (frictional force) of a weighted cylinder package riding on a rotating disc wetted by the test sample. The bottom of the cylinder package was mild steel, glass, or PET and the rotating disc was stainless steel or delrin (plastic). The disc had a diameter of <NUM> inches and the rotation speed was typically <NUM> rpm. The drag force, using an average value, was measured with a solid state transducer, which was connected to the cylinder by a thin monofilament fishing line. The drag force was monitored with a strip chart recorder. The coefficient of friction (COF) was calculated by dividing the drag force (F) by the weight of the cylinder package (W): COF = F/W.

Three to five milliliters of the lubricant sample were applied with a disposable pipette onto the rotating track. The typical time for the test lubricant to reach a steady state was about <NUM>-<NUM> minutes. During this time, the liquid lubricant film on the track was replenished as needed. The average force for the last <NUM> minute (after the lubricant reached a steady state) was used as the final drag force for the "wet" mode. To continue with the "dry" mode test, the liquid lubricant was not replenished. As the liquid lubricant film continued to dry with time, the drag force changed in different ways depending on the type of lubricant. The "dry" mode COF was determined when the applied liquid film appeared dry by visual inspection and confirmed by gentle touching of the track. The drying time was about <NUM> to <NUM> minutes.

Example <NUM> tested, as a control, the ability of a silicone based "dry lubricant" for PET containers to lubricate glass bottles on a stainless steel conveyor. For this example, the formula in Table <NUM> was used.

The silicone based lubricant was tested using the Slider Lubricity Test. The silicone based lubricant was tested using PET cylinder on a delrin slider and a glass cylinder on a metal slider. The results are shown in Table <NUM>.

The silicone based lubricant was effective at lubricating a PET cylinder on a plastic surface and produced acceptable coefficients of friction below <NUM> and specifically <NUM> and <NUM> when run in the wet and dry modes respectively. However, the silicone based lubricant was not effective at lubricating glass on a metal surface and produced coefficients of friction above <NUM>, and specifically <NUM> and <NUM> when run in the wet and dry modes respectively. This is consistent with what has been observed in the field and what the formulas of the present invention are trying to overcome.

It has been observed in the field that traditional glass and metal lubricants do not work well (i.e. do not produce an acceptable low coefficient of friction) when run in a dry mode, that is when applied for a period of time, and then turned off for a period of time while containers and packages continue to be moved along the conveyor surface. Example <NUM> tested, as a control, the ability of traditional glass and metal lubricants to work in a "dry mode. " This example used Lubodrive RX™, a phosphate ester based lubricant, commercially available from Ecolab Inc. Paul, MN, and Lubodrive TK™, a fatty amine based lubricant, commercially available from Ecolab Inc. This example tested <NUM>% and <NUM>% solutions of Lubodrive RX™ and Lubodrive TK™ in water. Lubodrive RX™ and Lubodrive TK™ are typically used at <NUM> % concentrations. For this example, Lubodrive RX™ and Lubodrive TK™ were tested using the Slider Lubricity Test using a glass cylinder on a metal slider. The results are shown in Table <NUM>.

Table <NUM> shows that traditional glass lubricants do not work well in a "dry" mode even when the concentration was raised to a hundred times that of the typical use level of <NUM>%. Lubodrive RX™ and Lubodrive TK™ produced very acceptable coefficients of friction below <NUM> when used in the "wet" mode. However, when applied in a "dry" mode the coefficient of friction went above <NUM> in three cases, and <NUM> in a fourth case, even when the concentration was increased a hundred times the typical use level. These coefficients of friction are unacceptable in the industry.

Example <NUM> tested the fatty acid formula of the present invention compared to the silicone control of Example <NUM> and the glass lubricants of Example <NUM>. Specifically, Example <NUM> tested the impact of adding <NUM>% fatty acid (oleic acid) to the silicone based lubricant of Table <NUM> and running the lubricant wet and dry. For this example, a premix solution of neutralized oleic acid was prepared by adding <NUM> grams of triethanolamine and <NUM> grams of oleic acid to <NUM> grams of deionized water. A lubricant solution was prepared by adding <NUM> grams of silicone emulsion (E2140FG, commercially available from Lambent Technologies Inc. ), <NUM> grams of polyoxypropylene polyoxyethylene block copolymer (Pluronic F-<NUM>, commercially available from BASF, Mount Olive, NJ), <NUM> grams of methyl paraben, and <NUM> grams of the premix solution of neutralized oleic acid to <NUM> grams of deionized water. Example <NUM> was tested using the Slider Lubricity Test and tested a PET cylinder on a plastic slider and a glass cylinder on a metal slider. The results are shown in Table <NUM>.

The mixture of the silicone based lubricant plus <NUM>% oleic acid improved the glass on metal lubricity of the silicone based lube (see Table <NUM> control), wet or dry, while maintaining a good coefficient of friction for PET on a plastic surface when compared to the silicone based lube and the traditional glass lubricants (see Table <NUM> and Table <NUM> controls). In all cases, the coefficient of friction for the present invention remained below <NUM>.

Example <NUM> tested a phosphate ester compared to the silicone based lubricant control of Table <NUM>. Specifically, Example <NUM> tested the impact of adding <NUM>% phosphate ester to the silicone based lubricant of Table <NUM>, and running the lubricant wet or dry. For this example, a premix solution of neutralized phosphate ester was prepared by adding <NUM> grams of a <NUM>% aqueous solution of sodium hydroxide and <NUM> grams of Rhodafac RA-<NUM> phosphate ester (available from Rhodia, Cranbury, NJ) to <NUM> grams of deionized water. A lubricant solution was prepared by adding <NUM> grams of silicone emulsion (E2140FG, commercially available from Lambent Technologies Inc. ), <NUM> grams of polyoxypropylene polyoxyethylene block copolymer (Pluronic F-<NUM>, commercially available from BASF, Mount Olive, NJ), <NUM> grams of methyl paraben, and <NUM> grams of the premix solution of neutralized phosphate ester to <NUM> grams of deionized water. For this example, the Slider Lubricity Test was used and tested PET on a plastic slider and glass on a metal slider. The results are shown in Table <NUM>.

The mixture of the silicone based lubricant with <NUM>% phosphate ester improved the glass on metal lubricity of the silicone based lubricant (see Table <NUM> control), and improved the PET lubricity of the silicone based lubricant, wet or dry (see Table <NUM> and Table <NUM> controls). In all cases, the coefficient of friction for the present invention remained below <NUM> and at or below the very acceptable coefficient of friction of <NUM>.

Example <NUM> tested an amine acetate formula, compared to the silicone based lubricant control of Table <NUM>. Specifically, Example <NUM> tested the impact of adding <NUM>% amine acetate to the silicone based lubricant. For this example, a premix solution of acidified fatty amine was prepared by adding <NUM> grams of glacial acetic acid, <NUM> grams of Duomeen OL (available from Akzo Nobel Surface Chemistry LLC, Chicago IL), and <NUM> grams of Duomeen CD (also available from Akzo Nobel), to <NUM> grams of deionized water. A lubricant solution was prepared by adding <NUM> grams of silicone emulsion (E2140FG, commercially available from Lambent Technologies Inc. ), <NUM> grams of polyoxypropylene polyoxyethylene block copolymer (Pluronic F-<NUM>, commercially available from BASF, Mount Olive, NJ), <NUM> grams of methyl paraben, and <NUM> grams of the premix solution of acidified fatty amine to <NUM> grams of deionized water. For this test, the Slider Lubricity Test was used and tested PET on a plastic slider and glass on a metal slider. The results are shown in Table <NUM>.

The mixture of the silicone based lubricant with <NUM>% amine acetate improved the glass on metal lubricity of the silicone based lubricant (see Table <NUM> control), wet or dry, and improved the PET lubricity of the silicone based lubricant (see Table <NUM> and Table <NUM> controls). In all cases, the coefficient of friction of the present invention remained below <NUM>.

Claim 1:
A method for lubricating the passage of a container along a conveyor, comprising applying a lubricant composition to at least a portion of the container-contacting surface of the conveyor or to at least a portion of the conveyor-contacting surface of the container, the lubricant composition comprising:
a. from <NUM> to <NUM> wt. % of a water-miscible lubricant being a water-miscible fatty acid derivative, wherein the fatty acid comprises oleic acid, tall oil, a C<NUM>-C<NUM> fatty acid, and mixtures thereof;
b. from <NUM> to <NUM> wt. % of a water-miscible silicone material; and
c. from <NUM> to <NUM> wt.% water.