Water-Based Lubricants for Conveyor Belts

Abstract

The invention relates to water-based lubricants for conveyor belts. More particularly, the invention relates to water-based lubricants for conveyor belts for the drinks industry.

Claims

1. Water-based lubricant composition for conveyor belts, comprising: 4% to 30% by weight of at least one viscosifying component, 0.05% to 10% by weight of preservative substances that provide protection from soiling, water to 100% by weight, characterized in that the viscosifying component is a water-soluble carboxylic ester, or a mixture of a water-soluble carboxylic ester and a low molecular weight polyalkylene glycol.

2. Lubricant composition according to claim 1, further comprising one or more components selected from the group consisting of: 0.05% to 5% by weight of antiwear agent, 0.05% to 15% by weight of antifreeze, 0.05% to 15% by weight of anticorrosive, 0.05% to 5% by weight of antiwear agent, 0.05% to 5% by weight of defoamer, 0.05% to 5% by weight of wetting agent, 0.05% to 5% by weight of biocides, 0.005% to 2% by weight of fragrances.

3. Lubricant composition according to claim 1, characterized in that the preservative substances that provide protection from soiling are a compound or mixture selected from the group consisting of foaming or non-foaming emulsifiers from the class of ionic and nonionic surfactants.

4. Lubricant composition according to claim 2, characterized in that the antiwear agent is a water-soluble compound containing sulfur, phosphorus and/or nitrogen.

5. Lubricant composition according to claim 2, characterized in that the antifreeze is a compound selected from the group consisting of mono- and polyhydric alcohols and derivatives thereof.

6. Lubricant composition according to claim 2, characterized in that the anticorrosive is a compound selected from the group consisting of neutralized and non-neutralized carboxylic acids, neutralized phosphoric acids and/or phosphoric acid derivatives, benzoic acid and/or benzoic acid derivatives, triazole, alcoholamines, glycolamines.

7. Lubricant composition according to claim 2, characterized in that the defoamer is a compound selected from the group consisting of polysiloxanes or polymers of acrylate derivatives, the wetting agent used is a compound selected from the group consisting of ionic and nonionic surfactants, the biocide used is isothiazolone derivatives, and the fragrance used is a compound selected from the group consisting of alcohols, aldehydes, ketones, esters, alkenes, copper salts and/or zinc salts.

8. Use of the lubricant composition according to claim 1 in undiluted form.

9. Use of the lubricant composition according to claim 1 in a dilution of 1:1000.

10. Use of the lubricant composition according to claim 2 in undiluted form.

11. Use of the lubricant composition according to claim 2 in a dilution of 1:1000.

Description

EXAMPLES

[0030] The example formulations are produced by blending the majority of the individual constituents by means of a stirrer and heating to 70 C. for 30 min, followed by cooling and stirring-in of the temperature-critical constituents.

Example 1

[0031]

TABLE-US-00001 Viscosifying component: Nycobase 618 9.27% Antiwear: MPS 0.39% deion. water 90.34%

Example 2

[0032]

TABLE-US-00002 Viscosifying component: Nycobase 618 10.0% Antiwear: MPS 0.4% Biocide: Acticide MBS 0.10% Defoamer: ES 561 1.0% Anticorrosive: M 528 L 2.0% deion. water 86.5%

Example 3

[0033]

TABLE-US-00003 Viscosifying component: Nycobase 618 9.27% Preservative components that SurTec 192 0.5% provide protection from wear: SurTec 055 1.0% deion. water 89.23%

Example 4

[0034]

TABLE-US-00004 Viscosifying component: Nycobase 618 10.0% Viscosifying component: PG 200 2.5% Antiwear: Lubio EP 1 0.5% Biocide: Acticide MBS 0.15% Wetting agent: Hydrolite 5 0.9% Defoamer: ES 561 1.0% Anticorrosive: M 528 L 7.0% deion. water 77.95%

Example 5

[0035]

TABLE-US-00005 Viscosifying component: Nycobase 618 10.0% Antifreeze: Glycerin 2.5% Antiwear: Lubio EP 1 0.5% Biocide: Acticide MBS 0.2% Defoamer: ES 561 1.0% deion. water 85.8%

Example 6

[0036]

TABLE-US-00006 Viscosifying component: Nycobase 618 9.27% Antiwear: MPS 0.39% Preservative components that Redokon CDD A-H 0.014% provide protection from wear: Redokon CDD B 0.001% deion. water 90.325%

[0037] The components used are, as already mentioned above, PG 200, Nycobase 618. In addition, M 528 L is used, this being a mixture of various neutralized organic and inorganic acids which is sold by Cortec Corporation. Surtec 192 is a mixture of phosphates, silicates and amine-neutralized organic acids which can be purchased from SurTec Deutschland GmbH. SurTec 055 is a mixture of amines, silicates and hydrocarbons, and also anionic and nonionic surfactants, likewise from SurTec Deutschland GmbH. Hydrolite 5 is a pentanediol from Symrise AG. MPS is a salt of organic sulfur compounds which is sold by Raschig GmbH. Acticide MBS is a mixture of benzisothiazoles and methylisothiazolone from Thor GmbH. Lubio EP1 is a salt of an organic sulfur compound from Schafer Additivsysteme GmbH. ES 561 is a silicon-containing defoamer from Additivchemie Luers GmbH. Glycerol is sourced from Brenntag GmbH. Redokon CDD A-H and Redokon CDD B are chlorine dioxide solutions from Redokon GmbH.

[0038] The above example formulations were now tested for their efficacy.

[0039] 1. Antiwear

[0040] The SRV (oscillation/friction/wear) test is a commonly used test for quantification of the antiwear effect of lubricants. This is typically conducted using the steel-steel material pair. In the present case, for better applicability to the application, the POM (polyoxymethylene)/steel material pair is chosen. The wear rate was evaluated after a test duration of 6 hours at a load of 95 N/mm.sup.2.

TABLE-US-00007 TABLE 1 Product Wear rate [mm.sup.3/h] Interflon Fin Food lube AL 0.67 (oil-based dry lube made from mineral oil with PTFE) P3 Lubodrive RF 1.72 (oil-based dry lube made from hydrocarbon resin) Neomoscan G7 0.69 (water-based wet lube made from amine acetate) Example 1 0.04 Example 2 0.10

[0041] Table 1 shows that all three examples according to the present invention have distinctly lower wear rates than customarily used products.

[0042] 2. Spreading Characteristics

[0043] Good spreading characteristics are indispensable in the case of minimal lubrication volumes for maintenance of a constant lubricant film. Spreading characteristics are typically determined by contact angle measurements on the relative surface. The smaller the contact angle, the better the wetting of the surface.

TABLE-US-00008 TABLE 2 Contact angle [] Product on PBT after 15 s Example 4 38 Example 2 51 Lubostar CP 64 (water-based wet lube made from silicones)

[0044] Table 2 shows that the examples of the present invention have significantly better spreading characteristics than the frequently used Lubostar CP wet lube. The studies were conducted on PBT, a commonly used chain material.

[0045] 3. Tests on Conveying Devices with Various Pairs

[0046] Lubrication performance of the water-based example formulation was tested using a standard conveying device from Krones, using various relevant material combinations at room temperature and with a typical chain speed of 0.8 m/sec. The coefficients of friction were each determined using a 1 l glass water bottle with its original seal, a 1.5 l PET disposable bottle and a 1.5 k TetraPack. The container that was grinding against the conveyor chain was fixed to a spring balance with a cord.

TABLE-US-00009 TABLE 3 Coefficient of friction averaged over 120 sec with various material pairs POM/ Steel/glass POM/PET TetraPack Example 2 0.11 0.09 0.15 Example 4 0.07 0.15

[0047] Typically, the coefficients of friction of the various material pairs are in the range of 0.05 to 0.20. Table 3 shows the good lubricity of the compositions examined.

[0048] With the lubricant composition according to example 3, by way of evidence of the excellent performance with the least possible lubricant consumption, a 1.5 l PET disposable bottle was tested under the above-described conditions over a period of 4 hours. Over this time, a further 0.05 ml of lubricant was applied every 5 minutes. The coefficient of friction was constantly 0.09+/0.01 and hence within the ideal range for this material pair.

[0049] 4. Anticorrosive

[0050] In the case of use of water-based lubricants rather than an oil-based dry lubricant, adequate corrosion protection of the application technique should be assured, in order to protect components such as metering valves or spray valves. Typical corrosion protection tests are effected by storing relevant components in the lubricant formulation at elevated temperature.

TABLE-US-00010 TABLE 4 Stability of non-stainless steel components from application technology with respect to the lubricant Work steel at 70 C. Anticorrosion after immersion additive for 14 days Example 2 2% by weight adequate Example 4 7% by weight good Example 1 0% by weight unsatisfactory Neomoscan G7 No manufacturer data unsatisfactory

[0051] It can be seen in table 4 that adequately additized aqueous lubricant formulations can give adequate protection for corrosion-sensitive application technology.

[0052] 5. Cleaning

[0053] Soiling on food and drink containers should absolutely be avoided for hygienic and cosmetic reasons. Typical soiling includes normal dusts, particles of packaging, leaked food or drink product, wear particles from the chain and guide rail, and lubricant residues.

TABLE-US-00011 TABLE 5 Additive for Protection from prevention residue buildup on of soiling conveyor chain Example 3 present adequate Example 1 absent unsatisfactory P3 Lubodrive RF no manufacturer data unsatisfactory Neomoscan G7 no manufacturer data unsatisfactory DryExx SF no manufacturer data unsatisfactory (water-based dry lube)

[0054] The lubricants specified in table 5 were used to conduct the buildup of soiling both in continuous operation and in laboratory studies with an original PBT chain on the test conveyor. Surprisingly, a significant reduction in residue buildup was achieved in example 3.

[0055] 7. Defoamer

[0056] Excessive evolution of foam in the application of conveyor lubricants should be avoided owing to reduced tribological efficacy. Foam-forming lubricants also have worse applicability, particularly in the case of use of spray nozzles. The use of a defoamer in example formulation 5 visibly showed a significant reduction in the tendency to foaming.

TABLE-US-00012 TABLE 7 Defoamer Visible defoamer effect on the conveyor Example 4 present adequate Example 1 absent unsatisfactory

[0057] 8. Clarity

[0058] All formulations from examples 1 to 6 are clear solutions. The homogeneity of the system gives rise to distinct advantages in storage and transport stability, in homogeneous applicability without use of stirring units, and in avoidance of water-insoluble residues on the conveyor chain in the case of emulsions/suspensions.

TABLE-US-00013 TABLE 8 Type Appearance Example 1 solution clear Example 2 solution clear Example 3 solution clear Example 4 solution clear Example 5 solution clear Example 6 solution clear Lubostar CP emulsion cloudy Interflon Fin Food Lube AL suspension cloudy P3 Lubodrive RF solution clear Neomoscan G7 solution clear DryExx SF emulsion cloudy

[0059] 9. Flashing with Water

[0060] The cleaning of conveyor chains typically entails a production shutdown, since the friction characteristics are greatly affected by the amount of water applied and typically deteriorate in the case of elevated humidity. It is also not impossible that water bottles being conveyed will burst and that this will lead to locally limited flashing of the lubricant off the conveyor chain.

TABLE-US-00014 TABLE 9 CoF PET/PBT after flashing with excess of water (water:lubricant 500:1) Example formulation 2 +35% DryExx SF +70%

[0061] It has been found that, surprisingly, the formulation according to example 2, even in the case of flashing with 500 times the amount of water compared to the amount of lubricant applied to the chain, leads only to moderate deterioration in the coefficient of friction of 35%. This enables uninterrupted filling operation in the case of faults or in the event of cleaning, which was not the case compared to a known lubricant composition, since the coefficient of friction here was worsened by 75%.

[0062] 10. Applicability

[0063] The lubricant composition according to example 5 was applicable either by means of dosage via a metering valve or magnetic valve and subsequent application by means of a guide plate, or else via nozzles operated with compressed air or without compressed air. Particularly the possibility that the composition according to example 4 can be applied by means of compressed air-free nozzles in minimal amounts distinguishes this formulation from frequently used standard products, for example DryExx SF or P3 Lubodrive RF.

[0064] 11. Compatibility with Packaging, Application Technology and Chain Material

[0065] For further testing of the properties of the lubricant compositions of the present invention, immersion tests were conducted with gasket material, hose material, pipe elements, nozzle constituents, pump membranes and magnetic valves from standard application technology and POM chain material at 70 C. over 4 weeks with example formulation 5. No changes in the materials were detected.

[0066] For container compatibility, 1.5 l PET disposable bottles with the original seal, 1 l glass bottles, 0.5 l can and 0.5 lTetraPack were placed onto a glass surface wetted with formulation according to example 5 for 30 sec and then stored on a clean glass surface for 72 hours. Then there was a visual examination for changes to the material, such as stress, cracking or discoloration. In no case were any noticeable features observed.

[0067] 12. Biodegradability

[0068] All the example formulations mentioned are environmentally compatible and biodegradable to a high degree by virtue of the high water content, and by virtue of the very good biodegradability of the viscosifying agents used.