Aqueous Functional Fluid

FIELD OF THE INVENTION

The prescribed invention relates to a aqueous functional fluids that can be used in metal working operations, for example within the metal cutting, machining, grinding and tooling industries. More particularly, the invention relates to functional fluids exhibiting corrosion resistance.

BACKGROUND OF THE INVENTION

Various types of materials are used as functional fluids and functional fluids of various compositions find utility in many different applications. Among such applications are included electronic coolants, hydraulic fluids, metal working fluids, lubricants, damping fluids, heat transfer fluids and diffusion pump fluids.

There are principally three types of funtional fluids used in metal working: mineral, semi-synthetic and synthetic. Mineral coolants are inexpensive, but suffer from a restricted life; semi-synthetic coolants use chemicals to solubilize oil into water; aqueous based synthetic coolants do not contain oil and hence are much more stable. The present invention is concerned with a synthetic fucntional fluid.

Aqueous functional fluids, for such uses as lubricants, metal working fluids and hydraulic fluids, demonstrate significant advantages when compared with mineral oil based compositions as functional fluids. Particularly, aqueous based compositions have economic, environmental and safety advantages, as well as performance advantages compared with mineral oil formulations. As metal working fluids, aqueous functional fluids have been used in chip forming and non-chip forming metal working processes well known in the art, such as drilling, tapping, broaching, grinding, rolling, drawing, spinning, milling, bending and stamping.

The demand for aqueous type hydraulic fluids has been increasing because of the economic and safety (e.g. high non-fiammability) advantages of such fluids over nonaqueous oil type hydraulic fluids. The increasing cost of oil-based products highlights the economic advantage of aqueous functional fluids over non-aqueous, oil type, functional fluids and has accelerated the demand for aqueous functional fluids.

To take full advantage of their economic, environmental and safety advantages, aqueous functional fluids must not only provide the necessary functions in the particular use to which they are put, but should preferably must also exhibit numerous other properties such as, for example, high stability during storage and use, resistance to decomposition and anti corrosion. These properties are particularly important to the life and appearance of the metal components of metal working apparatus and hydraulic systems and to the useful life of the aqueous functional fluids. When used as a metal working fluid, for example, the aqueous functional fluid should not only provide the necessary cooling and lubricating functions, but it also desirably should be highly resistant to separation of its components during storage and use and it should provide protection against corrosion of the work piece and the metal working apparatus.

Although numerous aqueous metal working fluids are known in the art, those aqueous fluids have not entirely met the performance demands placed upon them by their users and often have been found wanting in various properties such as, for example, storage stability, stability during use and corrosion protection. Improved aqueous functional fluids are needed which overcome stability and corrosion problems of the prior art aqueous functional fluids.

In essence, therefore, a desirable functional fluid would keep a workpiece at a stable temperature, especially where working to close tolerances, maximize the life of the cutting tip by lubricating the working edge and reducing tip welding and prevent the growth of bacteria or fungi.

It is an object of this invention to overcome the deficiencies of prior art aqueous functional fluids, or, at leat, to provide the public with a useful alternative fluid.

SUMMARY OF THE INVENTION

According to the present invention there is provided a functional fluid composition, characterized in that the composition comprises a phased aqueous emulsion of an polyacrylamide co-polymer, one or more corrosion inhibitors and biocides, and a metal passivator.

The polyacrylamide polymers used in the composition of this invention are known and have previously found applications in the water, sewage, paper and pulp industries and these materials are characteristically safe around humans, animals and plant life. Such materials are thus conveniently used where environmental and health and safety considerations have to be taken into account.

A composition according to the present invention may be supplied in the form of a concentrate. Preferably, the aqueous emulsion of acrylic copolymer is present in a range of from 0.001% to 25% w/w in any such concentrate. The phased aqueous emulsion of polyacrylamide co-polymer is preferably a high molecular weight anionic polyacrylamide co-polymer.

In a preferred form of the invention, one component may serve as both a corrosion inhibitor and a biocide. Preferably, the corrosion inhibitors and biocides are present in a range of from 0.001% to 25% w/w of concentrate. The corrosion inhibitors and biocides are preferably sodium benzoate and/or boric acid. Sodium benzoate is used in the food and beverage industries and it is convenient if food and beverage grade product is used in the composition of the present invention.

Preferably, pH buffer is present in a range of from 0.001% to 99.999% w/w of the concentrate. The pH buffer is preferably an alkanolamine, more preferably a tertiary alkanolamine and more preferably, still the pH buffer is triethanolamine. . Triethanolamine buffers are used in cosmetic and dermatological formulations and thus has benefits, beyond the functional aspects of the composition, when compared with less favoured buffer materials

The metal passivator is preferably present in a range of from 0.001% to 25% w/w of concentrate. The metal passivator is preferably a triazole based compound and more

preferably an aromatic triazole. More preferably still the triazole is a tolutriazole amine derivative.

In a preferred form of the invention a defoaming/anti-evaporative agent is incorporated into the composition. The defoaming/anti-evaporative agent is present in a range of from 0.001% to 25% w/w of concentrate. The defoaming/anti-evaporative agent is preferably a C2-C8 aliphatic alcohol and more preferably still, N-butanol.

Cut metal surfaces are vulnerable to the effects of atmosphere and tendency to discolour is apparent. Although discolouration typically doesn't affect any functional aspects of a product it is generally visually undesirable. To this end, the composition of the invention preferably includes a water soluble long-term surface-protective film forming material. Such a water soluble long-term surface-protective film forming material is effective in a range of from 0.001% to 50% w/w of concentrate. The water soluble long-term surface- protective film is preferably a water soluble wax, for example a C 16-Cl 8 alkyl alcohol ethoxylate, preferably a mixture of cetearyl alcohol and ceteareth-30.

The composition of the invention may additionally include a surfactant, and surfactant is present in a range of from 0.001% to 37.5%. The surfactant is preferably but is not limited to nonyl phenyl ethoxylate.

The polymer-based metal removal, coolant and corrosion protectant fluid concentrate may further include a small amount of dye. The purpose of the dye is to colour the final concentrate to enable recognition of the type.

The dye is preferably a phthalocyanine type dye, for example, copper-phthalocyanine. In one preferred form of the invention the filler and emulsion assister may be water. In another preferred form the filler and emulsion assister may be anhydrous resulting in a 'reverse-emulsion' .

Any balance can be made up with a filler. The filler may be present in a range of up to 99.999% and the filler may be selected to act as an emulsion assister for the polymer- based metal removal, coolant and corrosion protectant fluid concentrate. An alternative

filler may be selected to modify the properties of the water-soluble long-term surface- protective film.

The polymer-based metal removal, coolant and corrosion protectant fluid concentrate may be used in a ratio of 1:5 to 1:20 by weight with water, for instance 1 kg. of polymer-based metal removal, coolant and corrosion protectant fluid concentrate to 5 to 20 kg. of water. These solutions give high temperature-lowering rates to metal surfaces in metal removal processes.

In a further form therefore the invention is said to reside in a functional fluid concentrate having 0.01% to 2.5% w/w aqueous emulsion of acrylic copolymer, 0.05% to 10% w/w of corrosion inhibitors and biocides, 0.1% to 7.5% w/w of a metal passivator, 1% to 85% w/w of apH buffer, 0.01% to 2.5% w/w of a defoaming/anti-evaporative agent, 0.01% to 5% w/w of a water soluble wax, 0.003% to 3% w/w of a phthalocyanine dye and 0.01% to 5% w/w of a surfactant..

More preferably the invention is said to reside in functional fluid concentrate with a pH adjusted to approximately 9.5 having 0.5% w/w anionic aqueous emulsion of acrylic copolymer, about 7.5% w/w corrosion inhibitors and biocides, 37.5% w/w pH buffer, 2.5% w/w metal passivator, 1% w/w defoaming/anti-evaporative agent, 1% w/w water soluble wax, 0.03% w/w phthalocyanine dye and about 50% w/w nonyl phenyl ethoxylate, filler and emulsion assister.

The concentrate may further include a functionless proprietary synthetic signature compound for security and identification purposes.

In a further aspect of the invention there is provided a method of preparing a functional fluid as described, said method characterised by the steps of :

1. Place de-ionised water in mixing vat and adding there to a corrosion inhibit or and biocide;

2. Whilst mixing heat the solution from step 1 to 60° to 65° C and mix until dissolved thoroughly;

3. Adding a metal passivator to the solution from step 2;

4. Adding a defoaming/anti-evaporative agent and mixing until dissolved thoroughly;

5. Adding a buffer to the mixture from step 4;

6. Adding a dye to the mixture from step 5;

7. Adding an polyacrylamide co-polymer slowly to the solution from step 6and mixing thoroughly;

8. Adding a surfactant to the solution from step 6;

9. Adding a defoaming agent/anti-evaporative agent to the solution from step 8; and

10. Optional add a pre-prepared signature to the solution from step 9 .

This then generally describes the invention but to assist with understanding reference will now be made to a particular example and a method of mixing the concentrate which has been found to be efficacious.

DESCRIPTION OF THE PREFERRED EMBODIMENT

EXAMPLE

The following ingredients are assembled and pre-prepared where indicated:

1. De-ionised water 39,950.Og

2. Sodium benzoate (crystalline)2,500.0g 3. Boric acid (granular) 5,000.Og

4. Tolutriazole amine derivative 2,500.Og

5. Pre-prepared 10% W/W aqueous emulsion of water-soluble wax 10 ₅ 000.0g

6. Triethanolamine 37,500.Og

7. Copper phthalocyanine 30.Og

8. Polyacrylamide polymer 500.0g

9. Nonyl phenyl ethoxylate l,000.0g 10. N-butanol l,000.0g

11. Pre-prepared 0.025% W/W aqueous solution of signature compound 20.Og TOTAL 100,000.0g

The foregoing ingredients comprise those ingredients representing a composition in accordance with the invention, and required to manufacture 100 kg. of the material. The composition prepared from the ingredients immediately described in the following order:

Note: the composition is continuously mixed during the addition of all ingredients until finished.

The mixer should be a vat type with anti-cavitation, propeller-type mixing attachment.

It is important to heat the de-ionised water and corrosion inhibitor/biocide admixture because the solution is otherwise super-saturated and will not combine further ingredients.

The 10%W/W water-soluble wax emulsion should be pre-prepared added to the already heated and dissolved de-ionised water and corrosion inhibitor/biocide solution because the resulting solution is otherwise super-saturated and will not combine further ingredients.

Similarly, it is important to add the acrylic copolymer in the order described above because adding it either earlier or later in the mixing process will result in the solution becoming super-saturated with the consequent precipitation of already added ingredients and failure to combine further ingredients.

As discussed above the described composition can then be used in a ratio of 1 :5 kg. to 1 : 10 kg. of water, alternatively the concentrate may be used in proportions of 1 : 1 kg. to 1 :20 kg. W/W with water. Also the concentrate may be diluted 1 : 1 to 1 : 10 kg. of water during manufacture and be supplied ready for use.

In an alternative arrangement the invention may be turned into a paste of varying consistencies for other machining, drilling and metal removal applications, by adding 15 to 25 kg. of the anionic aqueous emulsion of acrylic copolymer.

This invention has been developed with properties that decrease the temperature of tooling used in metal removal processes; the temperature of machined components is also reduced. These characteristics of the invention will enable increased endurance of such tooling in relation to wear and stresses arising out of fatigue and temperature cycling. Cutting and machining cycles operating with this invention will increase in productivity from reduced machining times and part-processing. The improvements as a result of these factors will ensure a greater degree of surface finish on the machined components and greater dimensional uniformity. The inherent properties of this invention will limit workplace hazards with regard to cleanliness in the workplace and general environmental working conditions for persons handling the fluid. Maintenance and cleaning of machinery, manufactured components and the workplace will be minimized. The lack of separation of the ingredients of this invention will mean less maintenance and replenishment of volumes used whilst also preventing bacterial growth. Waste removal costs will be cut with regard to environmental risks and practices no longer being a factor.

This invention has been developed to intrinsically provide advanced corrosion protection to both machine and part during metal removal operations. This corrosion protectant function has been developed to provide substantial protection against atmospheric, galvanic, oxidation/reduction and other stoichiometric- and thermodynamic- based corrosive events long after the metal removal process has been completed. The corrosion protection afforded by this invention arises only out of an original combination of proven bio- and human safe chemicals operating synergistically, and in further synergy with the polymer fraction of the invention. Accordingly, further advantage will be conferred to manufacturing operations involving metal removal

processes employing this invention by means of machine, metal removal tooling and production part corrosion protection. Operator safety, both short and long term, will be enhanced by this invention. The distinguishing feature of corrosion protection intrinsic to this invention lies in the creation of a non-toxic, surface active, bio-compatible corrosion-protecting film on machine surfaces and parts. This protective film may be left intact for more or less extended periods without breakdown but at all times may be washed off with water when required.

Throughout this specification various indications have been given as to the scope of the invention. The invention is not limited to any one of these but may reside in two or more of these combined together. The examples are given for illustration purposes only and not for limitation. Further advantages and improvements may well be made to this invention without deviating from its scope. Although the invention is shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made there from within the scope and spirit of the invention, which is not to be limited to the details disclosed herein.