Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Reexamination Certificate
2001-12-21
2003-04-15
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
C508S469000, C072S042000
Reexamination Certificate
active
06548456
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to metal working fluid being oil-in-water emulsions and to the use of said metal working fluids in metal working processes like elastic deformation, plastic deformation and cold and hot working of metals.
BACKGROUND OF THE INVENTION
In Japanese patent application 54005847-A a metal working lubricant is disclosed which is based on 10-100 g/l of oxalic acid or oxalate, such as ferric oxalate, 5-80 g/l polyvinyl pyrrolidone having a mol.weight of 400-700,000 and/or a water soluble copolymer formed from vinyl pyrrolidone and other vinyl monomers such as vinyl acetate acrylic acid or like and 5-150 g/l of water soluble Ti organic compound. Such a lubricant can be applied to the metal surface to be worked by spraying, roll coating etc. Optionally, the coating is heated at 60-90° C. for increasing its adhesion and smoothness. However, such a metal working lubricant is not an oil-in-water (o/w) emulsion but an aqueous solution containing the above-mentioned water soluble ingredients.
The present invention relates to metal working fluids being oil-in-water emulsions comprising surfactants for emulsifying oil in water and to the preparation of stable emulsions having oil concentrations up to about 20 wt. % in their final use. Next to other relevant properties, the emulsions used as metal working fluids have to fulfil two performance properties of major importance: lubrication and cooling. Performance properties are very much related to the colloid-chemical properties of the emulsion. A stable performance requires a good control of these colloid-chemical properties of the emulsion.
Unfortunately, emulsions are quite unstable fluids. For example, they often show tendency to coalescence resulting in an increased mean particle size, changed particle size distribution and finally in oil and/or water separation.
This instability is even more pronounced when operating under varying and severe process conditions. In this respect variables like make-up water quality/composition, temperature, pH, tramp oil, shear and metal fines in the emulsion are considered important and crucial.
In view of the above it is brought forward that the values of these variables can vary over wide ranges, well-known to those skilled in the art. For example, water hardness values of between 0 dH (demineralised water) and 40 dH for make-up water are observed. Also known is that after preparation of the emulsion the ionic strength and/or water hardness may change/increase significantly during the operation due to evaporation of water or incoming metal fines and ions, resulting in a reduction or loss of relevant properties like emulsion stability, film forming properties and dispersing capacity.
Such instabilities of emulsions are highly unwanted. Users of metalworking emulsions strongly prefer stable emulsions having properties/performance not changing in time. Therefore, in the research and development area, producers of these emulsions will strive for maximisation of the emulsion stability, especially under practical, varying operating conditions.
For overcoming above stability problems it is proposed in the prior art to stabilise emulsions electrostatically and/or by steric hindrance. Steric hindrance is a very effective tool in stabilising emulsions against coalescence and is described in literature extensively. For obtaining this steric stabilisation of emulsions polymeric surfactants with hydrophilic and lipophilic moieties are successfully applied in different type of industries.
Surprisingly it has been found that the stability problems of metal working fluids being oil-in-water emulsions can be solved by using one or more alkylated polyvinylpyrrolidones as emulsifiers. Surprisingly, this type of emulsions does not only show a high emulsion stability against oil coalescence under varying and severe processing conditions but also show other advantages like
narrow distribution of the droplet size of the metal working emulsions according to the invention;
a high stability against varying quality/composition of the make-up water. Different from the alkylated polyvinyl pyrrolidones, other polymeric surfactants may contain polyoxyethylene groups as hydrophilic moiety. The water solubility of these groups is quite sensitive to the quality/composition of the make-up water (salts dissolved in the water phase). This varying water solubility does affect the HLB (hydrophile-lipophile-balance) of the surfactant and thus also emulsification and emulsion stability;
a high capacity of dispersing metal fines in the metal working fluid; very good lubricant film forming characteristics, even under low speed conditions (plate-out on steel; ≧200 mg/m
2
per % wt. oil);
More in particular the alkylated polyvinylpyrrolidones are based on vinylpyrrolidone and one or more compounds selected from the group consisting of olefins and alkyl (meth)acrylates. In this respect the olefins are C
4
-C
30
&agr;-olefins, preferably C
10
-C
22
&agr;-olefins, whereas the alkyl (meth)acrylates are C
4
-C
30
alkyl (meth)acrylates, preferably C
10
-C
22
alkyl (meth)acrylates.
The alkylated polypyrrolidones may be illustrated by the formula
wherein R
1
-R
5
=H, C
1-30
alkyl and R
6
=C
2
-C
30
alkyl,
and x and y have such values that the alkylated polyvinylpyrrolidones have a Mw (weight average) of 1,000 up to 5,000, preferably 2,000 up to 25,000. The molecular weight of a polymeric compound cannot be measured accurately. The results are very depending on the applied method and even the selected reference compound. The molecular weights (weight averaged) mentioned were measured by Gel Permeation Chromatography, unless otherwise stated. The average MW's must be considered as indications, rather than absolute values.
The alkylated polyvinylpyrrolidones (APVP's) can easily be prepared by copolymerisation of vinylpyrrolidone and an &agr;-olefin or alkyl(meth)acrylate, well-known to those skilled in the art and also described in U.S. Pat. Nos. 3,423,381 and 3,417,054.
The metal working fluids according to the invention comprise alkylated polyvinylpyrrolidones wherein the vinylpyrrolidone content in the alkylated polyvinylpyrrolidone is from 5 to 80 mol. %. preferably from 10 to 60 mol. %,
According to their composition the alkylated polyvinylpyrrolidones are soluble in lubricant base oils and have a limited water solubility, a water solubility strongly reduced if compared with that of the (unalkylated) polyvinylpyrrolidones. The water solubility of polyvinylpyrrolidones is too high for making these compounds surfactants with sufficient emulsion stabilising capacity. By alkylation of polyvinylpyrrolidones the water solubility is reduced and APVP's are obtained with HLB-values in the more appropriate range. In this respect it is pointed at the Handbook Kirk Othmer, fourth ed., vol. 7, page 881, indicating that oil-in-water (o/w) emulsions (i.e. the type of emulsions according to the invention) are best stabilized by water-soluble emulsifiers and water-in-oil (w/o) emulsions are best stabilized by oil-soluble ones. In the table on page 881 of the Kirk Othmer reference the o/w emulsifiers do have a HLB-value in the range of 8 to 18, i.e. a high hydrophilic moiety content (which is contrary to the alkylated polypyrrolidones applied according to the present invention).
In view of the above it is brought forward that alkylated polyvinylpyrrolidone copolymers are marketed by GAF/ISP under
the trade name AGRIMER AL series, being dispersing agents for improved film formation of micro-emulsions for plant and crop protection, veterinary dips, knapsack sprayers and wood treatment, and under
the trade name ANTARON V series:
as mineral oil soluble dispersant used as viscosity-index improver, pour-point depressant, and sludge and detergent dispersant. Dispersant for graphite and molybdenum disulphide based lubricants;
protective colloid in bulk high solid dispersions; applied in paints, inks and coatings, and as
temporary coatings; oil soluble, water resistant coatings, e.g. replacement for l
Broekhof Nicolaas Leonardus Johanna Maria
Mulder Hendrik Laurens
Smits Robertus Petrus Jozef Maria
Howard Jacqueline V.
Quaker Chemical Corporation
Young & Thompson
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