Patent Application
20050288191
The present invention relates to conveyor lubricant compositions and to methods of using the same.
In commercial container filling or packaging operations, the containers typically are moved by a conveying system at very high rates of speed. In most packaging operations, the containers are moved along conveying systems, usually in an upright position, with the opening of the container facing vertically up or down, and are moved from station to station, where various operations are performed including, for example, filling, capping, labeling, sealing, and so forth. Thus, in particular in the beverage industry, it is important that the containers move without hindrance along the conveyor such that no liquid is spilled onto the conveyor during the times when the containers are open. This is particularly important for dairy based beverages such as milk because milk can coagulate on the equipment surfaces. Lubricants are thus commonly used to ensure the appropriate movement of the containers on the conveyor.
Lubricant compositions are used on conveying systems in the beverage industry during the filling of containers with dairy products or other beverages. The conveyor systems are thus typically lubricated to reduce friction between the package and the load bearing surface of the conveyor. These lubricants are typically applied to the conveyor belts and/or the containers to reduce friction between the container and the conveyor which facilitates unhindered conveyance of bottles on the conveyor belt. These lubricants may also be referred to as chain conveyor or belt lubricants.
Not only are good lubricating properties important, there are other important considerations when selecting a lubricant for use in the beverage bottling industry. One such consideration is that the lubricant be compatible with the beverage such that it does not form coagulates or other solid deposits when it accidentally contacts spilled beverages on the conveyor system. Formation of such deposits on a conveyor can change the lubricity of the conveyor and require shutdown to permit cleanup. The lubricant must also be readily cleaned from the equipment.
In the commercial distribution of most beverages, the beverages are packaged in containers of varying sizes, such containers being in the form of cartons, cans, bottles, tetrapack packages, waxed carton packs, and other forms of containers. The containers, in addition to their many possible formats and constructions, may comprise many different types of materials, such as metals, glasses, ceramics, papers, treated papers, waxed papers, composites, layered structures, and polymeric materials.
Polymeric materials are commonly employed in the beverage industry. Examples of commonly used polymeric materials include, for example, polyolefins such as polyethylene, polypropylene, polystyrene, copolymers thereof; polyesters and copolymers thereof such as polyethyleneterephthalate and polyethylenenaphthalate; polyamides and copolymers thereof; polycarbonates and copolymers thereof; and so forth and mixtures thereof. Some aqueous conveyor lubricants are incompatible with thermoplastic beverage containers made of polyethylene terephthalate (PET) and other plastics, for example, and can cause stress cracking (crazing and cracking that occurs when the plastic polymer is under tension) in carbonated beverage filled plastic containers.
There remains a need in the industry for to provide an alternative to currently available lubricants for containers and conveyors that overcome one or more of the disadvantages of currently used lubricants.
The present invention relates to lubricants for conveyors and for containers which includes an effective lubricating amount of at least one lubricant and at least one protectant which is an alkanolamide, alkyl ether sulfonate, acetylenic diol, alkyl ether carboxylic acid or salt thereof, alkylated diphenyloxide disulfonic acid or salt thereof or mixture thereof.
The present invention is not limited by the type of lubricant employed. In some embodiments, the lubricant is an amine-based lubricant such as an amine acetate, a fatty acid or salt thereof, silicone including polymers, emulsions and oils, nonionic surfactant lubricants, phosphate esters and mixtures thereof.
Other amine based lubricants include the fatty amines, primary, secondary and tertiary amines, diamines, alkanolamines, and so forth.
Nonionic surfactant lubricants include, but are not limited to, the ethylene oxide/propylene oxide block copolymers, alcohol alkoxylates, such as the alcohol ethoxylates and alcohol propoxylates, and so forth.
As used herein, the term “block copolymer” shall hereinafter refer to diblocks, triblocks, and so forth.
In some embodiments, the lubricant includes hydrogen peroxide. In these embodiments, the protectants found to be very effective include the alkanolamides, alkyl ether carboxylic acids or salts thereof or mixtures thereof.
In one embodiment, the lubricant composition includes an ethylene oxide/propylene oxide block copolymer and hydrogen peroxide.
The protectants, in general, have been found to be useful at concentrations of about 1 wt-% to about 25 wt-%. For some lubricants, the effective concentration may be about 1 wt-% or less. For other lubricants, the effective concentration may be from about 5 wt-% to about 15 wt-%. This has been found to be dependent on, for one thing, the combination of the lubricant and the protectant employed.
The lubricants are useful at concentrations of about 0.1 wt-% to about 50 wt-%, more suitably about 0.5 wt-% to about 20 wt-%, and most suitably about 1 wt-% to about 10 wt-%.
Other optional ingredients include, but are not limited to, surfactants, antimicrobial agents, preservatives, water conditioning agents, and so forth. Such additives are known to those of skill in the art.
The present invention further relates to methods of using the lubricant compositions according to the present invention. One such method includes lubricating a continuously-moving conveyor system for transporting packages wherein the conveyor system is wetted with an aqueous lubricant composition including at least one ether carboxylate and at least one foam destabilizer according to the present invention.
The lubricant composition may be provided to the end user as a concentrate, or the method may include the step of diluting the concentrate prior to application of the concentrate to the desirable location of the conveyor system, or the lubricant may be supplied in diluted use form. The lubricant composition may be applied to the conveyor system using any techniques known in the art such as a spray method. Application may involve applying the lubricant to the conveyor and/or to the package or container itself.
These and other advantages of the present invention will be more readily understood by those skilled in the art from a reading of the following detailed description.
While this invention may be embodied in many different forms, there are described in detail herein specific embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.
The present invention relates to lubricant compositions which include at least one additive or protectant for inhibiting stress cracking and hazing of polymeric articles, particularly those formed from polyolefins, polyesters, or mixtures thereof. In particular, the lubricant compositions find utility in lubricating conveyors wherein articles formed from polyalkylene terephthalates such as polybutylene terephthalate and polyethylene terephthalate.
A. Protectants
The protectants which find utility herein include alkanolamides, alkyl ether sulfonates, acetylenic diols, alkyl ether carboxylic acids or salts thereof, alkylated diphenyl oxide disulfonic acids or salts thereof or mixtures thereof.
Suitable commercially available examples include, but are not limited to, alkanolamides such as Alkamide® DC-212/SE available from Rhone-Poulenc Co.; alkyl ether sulfonates such as Avanel® S74 available from BASF Corp.; acetylenic diols such as those sold under the tradename of Surfonyl® 104 available from Air Products; alkyl ether carboxylic acids or salts thereof such as those sold under the tradename of Sandopan® DTC available from Clariant Corp.
Alkylated diphenyl oxide disulfonic acids or salts thereof available under the tradename of Dowfax® such as Dowfax® 2A1 available from Dow Chemical Co. are found to be beneificial when employed in combination with acetylenic diols such as Surfonyl® 14.
The protectants are suitable for use in amounts of about 0.1 wt-% to about 20 wt-%, and mores suitably about 0.5 wt-% to about 15 wt-%. These amounts may vary depending on the type of protectant or mixture thereof which is employed, as well as the lubricant base employed.
B. Lubricants
The present invention is not limited by the lubricant which may be employed herein. Any lubricants known in the art may find utility in the compositions of the present invention and including synthetic lubricants such as silicones, glycerin, petroleum based lubricants such as mineral oil, and natural lubricants including fatty oils and animal and vegetable oils including those which are edible.
Lubricants come in a variety of classes including, for example, fatty acids and salts thereof, or soaps; fatty amines; alkanolamines; primary, secondary and tertiary amines; diamines; amphoteric, cationic, anionic and nonionic surfactants; phosphate esters; silicones; methyl parabens; and so forth. Acids also may come in a salt form which has been neutralized with a base such as potassium or sodium hydroxide.
More specific examples includes, but are not limited to, synthetic hydrocarbons; organic esters; high molecular weight alcohols; carboxylic acids including oleic acid or salts thereof; perfluoroalkylpolyethers (PFPE); silicates; silicones including oils and emulsions as well as the polymers thereof; fluoropolymers such as chlorotrifluoroethylene; polyphenyl ethers; poly(alkylene) glycol(s) including polyethylene and polypropylene glycols; oxypolyalkylene glycols; copolymers of ethylene and propylene oxide, polyhydroxy compounds; ethoxylated amines; primary, secondary and tertiary amines; alkanolamines; fatty acid amines including N-coco B-Amino propionic acid amphoteric surfactant; perfluoroalkylpolyethers (PFPE); polyhydroxy compounds; and so forth and mixtures thereof. This list is intended for illustrative purposes only, and is not intended to limit the scope of the present invention.
In some embodiments, the lubricants employed are silicones including polymers, oils and emulsions; fatty acids and salts thereof; amines such as amine acetates; and nonionic surfactants.
In one embodiment, a nonionic surfactant which is an ethylene oxide/propylene oxide (EO/PO) block copolymer is employed. A specific example of such EO/PO block copolymers include triblock copolymers which have the following general structure:
(EO)x(PO)y(PO)z
wherein EO represents ethylene oxide residue, PO represents propylene oxide residue, x equals an integer of about 2 to about 100, y equals an integer of about 2 to about 100 and z equals a integer of about 2 to 100 and those having the following general formula:
(EO)x(PO)y(EO)z
wherein x, y and z are independently selected from the group of numbers that range from about 2 to about 100. These lubricants are available from BASF under the tradename of PLURONIC® and include PLURONIC® 10R5 and PLURONIC® F108 which is an EO—PO-EO triblock polymer. As used herein the term “block copolymer” shall be hereinafter used to include diblocks, triblocks, and so forth.
Another example of suitable lubricants are the alkoxylated alcohols including ethoxylated and/or propoxylated alcohols. A specific example is TOMADOL® 45-13, an alcohol ethoxylate which includes a 14-15 carbon alcohol with 13 moles ethylene oxide available from Tomah Products, Inc. in Milton, Wis.
Another specific example are the alkyl polyglucosides available from Cognis North America in Cincinnati, Ohio under the tradename of GLUCOPON® including GLUCOPON® 220, 225, 425, 600 and 625.
Other specific examples of useful lubricants include oleic acid, corn oil, mineral oil available from Vulcan Oil and Chemical Products under the Bacchus® trademark; fluorinated oils and fluorinated greases, available from DuPont in Wilmington, Del. under the trademark Krytox®; siloxane fluids available from General Electric silicones, such as SF96-5 and SF 1147 and other silicone emulsions; synthetic oils and their mixture with PTFE available from Synco Chemical under the trademark Super Lube®; polyalkylene glycols from Union Carbide such as UCON® LB625 and CARBOWAX® 300; block copolymer surfactants such as UCON® 50HB660 ethylene oxide(EO)/propylene oxide (PO) monobutyl ether; and so on and so forth.
Lubricants are available in solid form as well. Examples include, but are not limited to, molybdenum disulfide, boron nitride, graphite, silica particles, silicone gums and particles, polytetrafluoroethylene (PTFE, Teflon), fluoroethylene-propylene copolymers (FEP), perfluoroalkoxy resins (PFA), ethylene-chloro-trifluoroethylene alternating copolymers (ECTFE), poly (vinylidene fluoride) (PVDF), and the like. The lubricant composition can contain an effective amount of a water-based cleaning agent-removable solid lubricant based on the weight of the lubricant composition. The lubricant composition can also contain a solid lubricant as a suspension in a substantially aqueous or non-aqueous liquid.
Lubricants are useful from about 0.1 wt-% to about 50 wt-% of the composition, suitably about 0.5 wt-% to about 20 wt-%, and most suitably about 1 wt-% to about 10 wt-%.
The above lists are not exhaustive, and are intended for illustrative purposes only, and not as a limitation on the scope of the present invention. One of ordinary skill in the art has knowledge of such lubricants. Suitable lubricants are described, for example, in commonly assigned U.S. Pat. No. 6,576,298, U.S. Pat. No. 5,925,610, US 5559087 and U.S. Pat. No. 5,352,376, each of which is incorporated by reference herein in its entirety.
The lubricant compositions used in the invention may be available as concentrates, or as diluted use solutions. As such, the lubricant compositions may contain water or a hydrophilic diluent, as a component or components in the lubricant composition as sold or added just prior to use. Suitably, the lubricant composition does not require in-line dilution with significant amounts of water, that is, it can be applied with little or no dilution.
Suitably, the lubricant compositions include about 1 wt-% to about 90 wt-% water, and more suitably about 25 wt-% to about 85 wt-% and most suitably about 50 wt-% to about 85 wt-%. Of course, such compositions can be further diluted during use.
The lubricant compositions may be diluted with water at a ratio of about 1:200 to about 1:1000, suitably about 1:600 to about 1:800 of the composition to water.
A variety of other optional ingredients may be incorporated into the compositions including, but not limited to, pH adjusters such as potassium or sodium hydroxide or other neutralizing agents, surfactants, emulsifiers, sequestrants, hydrotropes, solubilizers, other lubricants, buffers such as potassium carbonate, detergents, bleaching or decolorizing agents, antioxidants, preservatives such as methyl paraben, antistatic agents, binders, thickeners or other viscosity modifiers, processing aids, carriers, water-conditioning agents, antimicrobial agents, foam inhibitors or foam generators, film formers, combinations thereof, and so forth. The amounts and types of such additional components are apparent to those skilled in the art.
The lubricant compositions according to the invention are non-corrosive, and can also provide protective properties to plastic containers such as polyalkylene terephthalate containers including PET and PBT. However, the lubricant compositions according to the present invention can be used in any application where lubricity is desired, as well as on any of a variety of materials other than plastics such as glass, metal including aluminum cans, treated and coated papers, laminates and composites, ceramics, and so forth can be treated.
The term container as used herein may include any receptacle in which some material is or will be held or carried. Such containers come in a variety of shapes and sizes. The containers may include beverages, solid and non-solid foodstuffs, as well as non-food items. The containers may be employed in beverage operations such as breweries and soft drinks, fruit juices, water, alcoholic beverages such as wine, and so forth.
The lubricant composition can be applied to a conveyor system surface that comes into contact with containers, the container surface that needs lubricity, or both. The surface of the conveyor that supports the containers may comprise fabric, metal, plastic, elastomer, composites, or mixture of these materials. Any type of conveyor system used in the field can be treated according to the present invention.
The lubricant composition can be applied in any desired manner, for example, by spraying, wiping, rolling, brushing, or a combination of any of these, to the conveyor surface and/or the container surface. If the container surface is coated, it is only necessary to coat the surfaces that come into contact with the conveyor, and/or that come into contact with other containers. Similarly, only portions of the conveyor that contacts the containers need to be treated.
Test Methods
1. PET Bottle Sress Test (#Failures/24)
Standard 2-liter PET beverage bottles (commercially available from Constar International) were charged with 1850 g of chilled water, 31.0 g of sodium bicarbonate and 31.0 g of citric acid. The charged bottle was capped, rinsed with deionized water and set on clean plastic lines or paper towels overnight. The bottoms of 12 bottles were dipped in a 200 g sample of 0.5% lube solution which was prepared using DI water with 200 ppm added alkalinity. The bottles were then placed in a bin and 85.2 g of the lube solution is evenly distributed to the bottom of the bin. The bottles/bin were stored in an environmental chamber at 37.8° C., 90% relative humidity for 28 days. Burst bottles were tracked throughout the test. The bottles were removed from the chamber, observed for crazes, creases and crack patterns on the bottom. The bottles were rated using the following method, and an overall grade assigned.
0=No signs of crazing to infrequent small, shallow crazes.
0.5=Infrequent small, shallow to infrequent medium depth crazes, which cannot or barely be felt with fingernail.
1.0=Frequent small, shallow to infrequent medium depth crazes which cannot or barely be felt with fingernail.
1.5=Infrequent medium depth to infrequent deep crazes.
2.0=Frequent medium depth to infrequent deep crazes.
2.5=Infrequent deep crazes.
3.0=Frequent deep crazes.
3.5=Frequent deep crazes and looks like it should have been a leaker.
4.0=Leakers or Bottle burst before the end of the 14-30 day test.
The following base compositions having no added protectant were prepared according to the formulas found in Table 1.
Comparative examples A, B, C and D, without any protectant, were employed as the base compositions for testing a variety of compositions found in the table below. The protectant was added and an equivalent amount of DI water was removed from each formula. The compositions were then tested using Test Method No. 1 described above. The results are shown in the same table.
The combinations of lubricants and protectants, as well as the concentrations, found in table 6 exhibited superior results over other combinations.
The above disclosure is intended for illustrative purposes only and is not exhaustive. The embodiments described therein will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.
