Conveyor system lubricant

[0021] 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.

[0022] 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

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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-%.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

EXAMPLES

Test Methods

1. PET Bottle Sress Test (#Failures/24)

[0046] 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.

[0047] 0=No signs of crazing to infrequent small, shallow crazes.

[0048] 0.5=Infrequent small, shallow to infrequent medium depth crazes, which cannot or barely be felt with fingernail.

[0049] 1.0=Frequent small, shallow to infrequent medium depth crazes which cannot or barely be felt with fingernail.

[0050] 1.5=Infrequent medium depth to infrequent deep crazes.

[0051] 2.0=Frequent medium depth to infrequent deep crazes.

[0052] 2.5=Infrequent deep crazes.

[0053] 3.0=Frequent deep crazes.

[0054] 3.5=Frequent deep crazes and looks like it should have been a leaker.

[0055] 4.0=Leakers or Bottle burst before the end of the 14-30 day test.

[0056] The following base compositions having no added protectant were prepared according to the formulas found in Table 1. TABLE 1 Chemical Comp Comp Comp Comp description A B C D Si Emulsion Silicone 5.0 — — — lubricant Pluronic ® EO/PO/EO 0.3 — — — F-108 (BASF) triblock copolymer lubricant Methyl paraben Preservative 0.2 — — — Tomadol ® C14-15 — 5.0 — — 45-13 (Tomah alcohol/13 Products, Inc) moles ethylene oxide; lubricant Pluronic ® EO/PO/EO — 3.0 — — 10R5 (BASF) triblock copolymer lubricant Glucopon ® Alkyl — 1.0 — — 625 (Cognis polyglucoside No. America) surfactant; lubricant H2O2; 35% Calcium — 5.7 — — chloride Calcium Conditioner — — — 1.0 chloride Oleyl Lubricant — — — 7.5 diaminopropane Acetic acid; Neutralizer — — — 8.04 80% Lauryl propyl Lubricant — — — 3.0 diamine Dimethyl Lubricant — — — 4.5 lauryl amine Polyethylene Lubricant — — — 3.0 glycol coco amine Isotridecyl Detergent — — — 9.0 alcohol/9 mole ethoxylate Potassium Buffer — — 8.48 1.65 hydroxide; 50% Propylene Cold Temp — — 14.98 — glycol Solvent Na salt Fatty acid — — 20.00 — oleic acid lubricant DI water Carrier 94.5 85.3 56.54 62.31

[0057] 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. TABLE 2 Failures Grade Comparative A Nonionic lubricant 2 1.35 with H2O2 Comparative E Comp A with 10% 4 1.69 Avanel ® S-74 Comparative F Comp A with 20% 4 1.58 Avanel ® S-74 Comparative G Comp A with 5% 2 1.40 Alkamide ® DC 212/SE Example 1 Comp A with 10% 1 0.92 Alkamide ® DC 212/SE Example 2 Comp A with 5% 1 1.08 Sandopan ® DTC Comparative H Comp A with 10% 2 1.08 Sandopan ® DTC Comparative I Comp A with 0.5% 2 1.23 Surfonyl ® 104 Example 3 Comp A with 0.5% 1 1.33 Surfonyl ® 104 and 5% Dowfax ® 2A1

[0058] TABLE 3 Failures (#/24) Grade Comparative B Silicone emulsion 4 1.25 lubricant Comparative J Comp B with 10% 6 1.81 Avanel ® S-74 Comparative K Comp B with 20% 2.5 1.27 Avanel ® S-74 Example 4 Compa B with 5% 1 1.29 Alkamide ® DC 212/SE Comparative L Comp B with 10% 2 1.33 Alkamide ® DC 212/SE Comparative M Comp B with 5% 3 1.46 Sandopan ® DTC Comparative N Comp B with 10% 3 1.50 Sandopan ® DTC Example 5 Comp B with 0.5% 1 1.31 Surfonyl ® 104

[0059] TABLE 4 Failures (#/24) Grade Comparative C Fatty acid lubricant 6 1.13 Example 6 Comp C with 5% 6 1.81 Alkamide ® DC 212/SE Comparative O Comp C with 10% 2.5 1.27 Alkamide ® DC 212/SE Comparative P Comp C with 5% 1 1.29 Sandopan ® DTC Example 7 Comp C with 10% 2 1.33 Sandopan ® DTC Comparative Q Comp C with 0.5% 3 1.46 Surfonyl ® 104 Comparative R Comp C with 0.5% 3 1.50 Surfonyl ® 104 and 5% Dowfax ® 2A1 Example 8 Comp C with 5% 1 1.31 Avanel ® S-74 Comparative S Comp C with 10% 4 1.94 Avanel ® S-74

[0060] TABLE 5 Failures (#/24) Grade Comparative D Amine acetate 3 1.88 lubricant Example 9 Comp D with 5% 0 1.92 Alkamide ® DC 212/SE Comparative T Comp D with 10% 2 1.96 Alkamide ® DC 212/SE Comparative U Comp D with 5% 2 2.27 Sandopan ® DTC Example 10 Comp D with 10% 0 1.02 Sandopan ® DTC Example 11 Comp D with 1% 0 0.79 Surfynol ® 104 Example 12 Comp D with 1% 0 0.88 Surfynol ® 104 and 5% Dowfax ® 2A1 Example 13 Comp D with 5% 0 1.04 Avanel ® S-74 Example 14 Comp D with 10% 0 0.85 Avanel ® S-74

[0061] TABLE 6 Summary of Results Lubricant type Nonionic with Silicone Fatty Amine Protectant Type H2O2 Emulsion acid acetate alkyl ether No ≧20% ≦10% ≦10% sulfonate Alkanolamide ≧10% ≦10% ≦10% ≦10% Alkyl ether 5% Little or none ≧5% ≦10% carboxylate Acetylenic Diol No Yes No yes

[0062] The combinations of lubricants and protectants, as well as the concentrations, found in table 6 exhibited superior results over other combinations.

[0063] 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.