WO2008075947A1

WO2008075947A1 - Metal working lubricant composition comprising a graft block polymer surfactant

Info

Publication number: WO2008075947A1
Application number: PCT/NL2007/050664
Authority: WO
Inventors: Hendrik Laurens Mulder; Coen Johannes Hermanus Van Os; Robertus Petrus Jozef Maria Smits; Pieter Schellingerhout; Lee Thompson
Original assignee: Quaker Chemical B.V.
Priority date: 2006-12-19
Filing date: 2007-12-18
Publication date: 2008-06-26

Abstract

The present invention relates to a metal working lubricant composition comprising 0.05 to 30 % by weight of a graft block polymer surfactant, based on the total weight of the metal working lubricant composition, said graft block polymer surfactant having an number average molecular weight of 3000 to 70000 and having a backbone comprising a backbone moiety, hydrophobic blocks having a number average molecular weight of at least 300, and hydrophilic blocks having a number average molecular weight of at least 300, wherein the hydrophobic blocks project substantially in their entirety from the backbone to form grafts, and wherein the hydrophilic blocks form at least part of the backbone in conjunction with the backbone moiety or project substantially in their entirety from the backbone to form grafts, or a mixture of the two.

Description

Metal working lubricant composition comprising a graft block polymer surfactant

Field of the invention

The present invention relates to metal working lubricant compositions comprising a surfactant, particularly a graft block copolymer surfactant. The present invention also relates to methods of producing such metal working lubricant compositions and methods of their use.

Background of the invention

GB A 2.002.400 and GB A 2.117.398 to ICI Ltd., both incorporated by reference, disclose certain graft block copolymers and methods of their production. In particular, these graft block polymers are prepared by reacting a poly(hydroxy carboxylic acid) having a terminal carboxylic group with a polyalkylene glycol or a polyether polyol, respectively. The graft block copolymers can be used as wetting and dispensing agents, as emulsifiers, as emulsion stabilisers and in compositions for use in cutting oils and other metal working fluids and fluids for hydraulic power transmission. Metal working involves the treatment of ferrous and non-ferrous metals in processes such as deformation (e.g. hot or cold rolling, forging or pressing). Metal working fluids are often used in metal work, primarily as lubricants, but also to provide other roles such as cooling, corrosion inhibition, waste product removal, surface treatments etc. Such fluids are typically applied at or near the site of interaction between the tool and the metal, e.g. at the sight of machinery or rolling.

As the rates of metal working have increased and the quality demands of metal users have risen, a need for higher performance metal working fluids has emerged. These fluids must be capable of efficient lubrication at high speeds, but must also minimise the formation of deposits on the surface of the metal being treated. Such metal working fluids typically comprise water and a hydrophobic lubricating component (i.e. an oil) which is held in an oil-in-water emulsion by an emulsifier. The fluids will generally contain a number of additional compounds with various properties, such as corrosion inhibitors etc. Metal rolling is a particular field of metal work where suitable fluids are not generally available to meet the increasingly demanding requirements of the industry. Metal rolling can be achieved under "hot" or "cold" conditions.

In hot rolling the metal is rolled at a temperature above the re-crystallisation temperature. This allows large deformation of metal to be achieved and is used to manipulate material shape rather than alter its mechanical properties. Hot rolling is generally used to produce sheet metal and simple billets and the like.

In cold rolling the metal is rolled at a temperature below the re-crystallisation temperature. During the cold rolling the metal sheet can be annealed by heating it above the re-crystallisation temperature after every few rolling events; this relaxes the sheet which prevents the sheet from becoming brittle and cracking. Cold rolling is generally usually used to produce sheet and special bars such as machine shafts.

Rolling operations, both hot and cold, are used for many metals, but steel production is the largest commercial operation. It is important to use metal working fluids (i.e. rolling oils) to improve speed, reduction levels, prevent excessive wear and disperse heat build up.

This had led to rolling oil formulators formulating rolling oils that can "plate out" (i.e. the amount of oil deposited per unit area of sheet), a greater amount of oil to try to address the pressures placed on the mill owners. However, the increase in "plated out" oil needs to be readily removable during the annealing process, which typically occur at 600° to 700⁰C for batch annealing processes, to meet the steel sheet surface quality requirement.

The surface quality of cold rolled annealed metal sheets can be marred by the presence of black staining and surface carbon residues. Such sheet surface quality may not be suitable for use in certain fields, e.g. automotive application areas, where there is currently a designated maximum level of allowable surface carbon residues of 7 mg/m² for mill clean sheet. However, this sheet surface quality requirement appears to be in direct conflict with the pressures placed on mill owners to continually seek to run their mills at faster speeds to improve output, to reduce power consumption of the mill and to roll different and harder alloys.

Such surface staining and oily deposits on the rolled metal surface may arise as a result of lubricating oil dropping out of emulsion and being deposited on the metal surface. In this case the oils contaminate the surface of the metal, and during the annealing operation may be carbonised thus forming black deposits on the metal surface. The cleaning of the sheet metal and/or polishing to remove black marks is highly undesirable as it significantly adds to the cost of the rolling process.

There is therefore a need for a metal working fluid which is able to operate effectively in a cold rolling situation and which is capable of reducing surface contamination of rolled metal. This may be achieved to some extent by providing surfactants which are more stable than those available, thus preventing hydrophobic components from dropping out of solution. Such a metal working fluid would likely find utility in other metal working situations. Another important property of rolling oils (and metal working fluids in general) is the ability to tolerate the presence of iron fines. Iron fines are produced during the rolling process and it is important that a metal working lubricant composition is able to tolerate the accumulation of fines, and retain them largely within the body of the fluid rather than depositing them on the metal surface. As the fluid is typically reused several times, an emulsion which is not tolerant to such fines, i.e. which coagulates or clogs, will not generally be suitable. The amount of fines deposited on the metal surface is a significant cleanliness issue and should be minimised.

Another disadvantage of certain prior art metal working fluids is that they may be prone to inversion during the spraying process. Inversion occurs when the oil-in-water emulsion inverts to a water-in-oil emulsion as a result of the mechanical stress of very high pressure spraying. Typically the inversion event is short lived, but it may still be significant. The problematic effects of such inversions are two-fold: lubricating properties are lost in the inverted solution, and deposits of viscous hydrophobic components accumulate on the spray nozzle. The deposits of inverted solution at areas of high sheer build up over time and eventually the residue will enter the system as a high oil content "slug". The second effect is potentially more of a problem as such a slug of oil rich residue seriously contaminates the metal surface. Such inversion is often a problem with low molecular weight surfactants, e.g. monomeric surfactants. The performance of prior art higher molecular weight surfactants in this area is also not optimal, and accordingly there is a need for surfactants that perform better in this aspect. The property of resisting inversion is known as "invert stability". Generally, prior to the present invention, it has been difficult or impossible to achieve formulations for metal work which combine high emulsion stability with the desirable properties of good lubrication, good wetting properties and good cleanliness.

There thus remains a need in the area of metal work for improved surfactants which can stably emulsify lubricating oils and achieve good "plate out", exhibit inversion stability, lubricity, wetting properties, and film formation.

Summary of the invention

The present invention relates to a metal working lubricant composition comprising 0.05 to 30 % by weight of a graft block polymer surfactant, based on the total weight of the metal working lubricant composition, said graft block polymer surfactant having an number average molecular weight of 3000 to 70000 and having a backbone comprising a backbone moiety, hydrophobic blocks having a number average molecular weight of at least 300, and hydrophilic blocks having a number average molecular weight of at least 300, wherein the hydrophobic blocks project substantially in their entirety from the backbone to form grafts, and wherein the hydrophilic blocks form at least part of the backbone in conjunction with the backbone moiety or project substantially in their entirety from the backbone to form grafts, or a mixture of the two. The present invention further relates to the use of the metal working lubricant composition in metal working operations and metal removing operations.

Detailed description of the invention

The verb "to comprise" as is used in this description and in the claims and its conjugations is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition, reference to an element by the indefinite article "a" or "an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there is one and only one of the elements. The indefinite article "a" or "an" thus usually means "at least one".

According to this invention, two metal working operations are discerned. One metal working operation involves "metal working" (or "metal forming"), i.e. a process wherein metals are shaped and formed. Examples of such processes include drawing, cold rolling and hot rolling. Another metal working operation involves "metal removing", i.e. a process wherein metal is removed from a metal work piece. Examples of such processes include milling, cutting, turning, grinding and honing. In this description, the term "metal working" is intended to encompass both operations.

The graft block polymer surfactant

In a first preferred embodiment, the hydrophobic blocks in the graft block polymer surfactant project from the backbone to form grafts and the hydrophilic blocks are integral with the backbone.

Suitably, the hydrophilic block comprises a hydrophilic polymeric moiety having a number average molecular weight of between 300 and 5000, preferably 400 to 1000, which is essentially soluble in water to the extent of at least 5% by weight at 25°C, based on the total weight of the aqueous composition. It will be understood that there are a large number of potentially suitable hydrophilic blocks and block precursors which can be used in the present invention, and suitable hydrophilic blocks and hydrophilic block precursors will in general be apparent to the person skilled in the art. Suitable hydrophilic blocks are typically derived from polyvalent hydrophilic block precursors, e.g. divalent or trivalent molecules, the polyvalency allowing the precursors to be combined into the graft block copolymer surfactant, either as part of the backbone or as a graft. Where a hydrophilic block is to be integral with the backbone, it is preferred that the block precursor is substantially linear and has terminal reactive groups. Where the hydrophilic block is to form a graft, it is preferred that the block precursor molecule comprises at least two reactive groups located relatively close together at one end of the precursor, e.g. on a polyvalent head portion. Suitably the hydrophilic blocks are derived from hydrophilic block precursor molecules and are preferably selected from the group consisting of polyols, polyamines and polyaminoalcohols, more preferably from the group consisting of diols and diamines. In a particularly preferred embodiment, the hydrophilic block is a polymeric or copolymeric moiety derived from a hydrophilic, preferably water soluble, polymer or copolymer of a C₂ - C4 alkylene glycol. A preferred hydrophilic polymer or copolymer of a C₂ - C4 alkylene glycol is selected from the group consisting of hydroxy terminated polyethylene glycol (PEG), polypropylene glycol (PPO), EO-PO diblock polymers, EO-PO triblock polymers, mixed poly(ethylene-propylene glycol) polymers and mixed poly(ethylene-butylene glycol)polymers. A more preferred hydrophilic polymer or copolymer of a C₂ - C4 alkylene glycol is a hydrophilic polymer having a number average molecular weight of 300 to 5000, more preferably 400 to 1000, especially 400 to 800. Most preferably, the hydrophilic block is a PEG. Exemplary hydrophilic blocks are PEG400, PEGOOO and PEGiooo- It is generally preferred that the hydrophilic block makes up from 20% to 50% by weight of the graft block copolymer surfactant, preferably 30% to 45% by weight, based on the total weight of the graft block polymer surfactant.

Suitably, the hydrophobic block comprises a hydrophobic polymeric moiety. Suitable hydrophobic polymeric moieties are derived from PoIy(C₂ - C₁₂ α-olefins), polyacrylates, polystyrenes and selfcondensed fatty acids (e.g. polyhydroxyacrylic acid, vinyl acetate or polypropylene acid). The hydrophobic block is typically derived from a hydrophobic block precursor having a polyvalent head, preferably a divalent head, especially a dicarboxylic acid head or carboxylic anhydride head. The polyvalent head allows the hydrophobic block to be incorporated into the graft block copolymer surfactant with the hydrophobic polymer extending from the backbone as a graft.

In a particularly preferred embodiment, the hydrophobic polymer is a polymer or copolymer of a C₂ - Ci₂ α-olefin, in particular a polymer of an α-olefin having from 2 to 6 carbon atoms, e.g. ethylene, propylene, butene-1 and isobutene. Such a polymer may conveniently be provided by the residue of a polyalk(en)ylsuccinic anhydride block precursor. Preferably the hydrophobic block is derived from an alk(en)yl succinic anhydride of the formula:

R — CH CO

O CH₂ CO

wherein R is a hydrocarbyl substituent derived from a polymer of a Ci - Ci₂ α-olefin, said polymer containing a chain of from 15 to 500 carbon atoms. A particularly preferred hydrophobic block is derived from a polyisobutylene succinic anhydride (PIBSA) block precursor or an atactic polypropylene succinic anhydride block precursor having a number average molecular weight in the range of 300 to 5000, preferably 500 to 1500. Polyisobutylene succinic anhydrides are commercially available compounds made by reacting maleic anhydride with a polyisobutene, e.g. Glissopal 1000, 1300 and 2300 of BASF. Atactic polypropylene succinic anhydrides are disclosed in US 5.736.492 and US 5.900.466, incorporated herein by reference. In addition, it is well known in the art that polyisobutenes have terminal ethylenically unsaturated groups as well as internal ethylenically unsaturated groups, not all of which are capable to react with maleic anhydride. In addition, it is well known in the art that polyisobutenes may react in an ene-reaction with more than one molar equivalent maleic anhydride to form polyisobutylene bissuccinic anhydrides (PIBBSA). According to the present invention, the terms polyisobutylene succinic anhydride and PIBSA also include polyisobutylene bissuccinic anhydrides (PIBBSA).

The backbone moiety may be derived from essentially any polyvalent precursor molecule suitable to form bonds with the hydrophobic block precursors and/or hydrophilic block precursors via their respective reactive groups. Generally, polyols, polycarboxylic acids, polyaminoalcohols and polyamines form suitable backbone moieties. Polyols are particularly preferred backbone moieties. The polyol may be a diol, triol, tetrol and/or related dimers or trimers or chain extended polymers of such compounds.

It will be clear to the person skilled in the art that the reactive groups of the backbone moiety precursor, the hydrophilic block precursor and the hydrophobic block precursor will be selected such that they are complementary reactive, i.e. that they are able to form covalent bonds between each other. For example, the succinic acid moiety of a PIBSA molecule is able to form an ester bond with a hydroxy group of glycerol or with a hydroxy group of a PEG. The succinic acid moiety of a PIBSA molecule is also able to form an imide bod with a primary or secondary terminal amino group of a polyamine or a polyaminoalcohol.

The graft block copolymer preferably comprises a plurality of linked copolymer subunits, each comprising at least one hydrophobic block, at least one hydrophilic block and a backbone moiety. The copolymer subunits are preferably identical such that they form repeating subunits in the graft block copolymer. The copolymer subunits may be joined directly together or may, more preferably, be joined using a linker moiety, which generally will then form part of the backbone of the completed graft block copolymer surfactant. The linker moiety is preferably derived from a molecule having at least two reactive groups, i.e. is divalent, and which is capable of linking two subunits together. The exact structure of the linker moiety is not generally significant, given that its function, like the backbone moiety, is simply to link two reactive groups on the copolymer subunits. However, the linker moiety is preferably derived from a substantially linear molecule with terminal reactive groups, such that it is able to link to reactive groups on each of the copolymer subunits. The linker molecule is suitably a divalent hydrocarbyl group, e.g. a saturated or unsaturated aliphatic hydrocarbyl group, and is suitably derived from an aliphatic dibasic acid, preferably containing 2 to up to 20 carbon atoms, more preferably up to 12 carbon atoms. Suitably, the linker moiety is derived from a polycarboxylic acid, for example a di- or tricarboxylic acid. Dicarboxylic acids are preferred linkers, particularly linear α,ω-dicarboxylic acids. Particularly suitable are linear, saturated or unsaturated dicarboxylic acids having a chain length of between 2 and 10 carbon atoms, for example oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic acid or maleic acid and low molecular weight alkenyl succinic anhydrides (ASA), e.g. Ci - C24 ASA.

Generally, the copolymer subunit comprises two or more hydrophobic blocks, two or more hydrophilic blocks and a backbone moiety. In a preferred embodiment, the copolymer subunit comprises two hydrophobic blocks being present as grafts and two hydrophilic blocks, the hydrophilic blocks being integral with the backbone, the copolymer subunit comprising a further backbone moiety. In this preferred embodiment, each hydrophobic block may conveniently comprise a bifunctional or divalent head portion, each function or valent group of said head portion of each hydrophobic block being linked to different, preferably opposing, points on the backbone moiety, the other valent group of said head portion of each hydrophobic block being linked to one or other of the hydrophilic blocks. Thus, a subunit structure is provided in which a central backbone moiety is flanked by two hydrophobic blocks which, in turn, are attached to two hydrophilic blocks. These copolymer subunits are linked together to form the graft block copolymer. These copolymer subunits may be linked directly, i.e. via the hydrophilic block on one subunit to a corresponding hydrophilic block on another subunit, or may be linked via a linker molecule between the two hydrophilic blocks as mentioned above. By the terms hydrophobic block precursor, hydrophilic block precursor, backbone moiety precursor, and linker moiety precursor, it is meant precursor molecules which are reacted together, via complementary reactive groups present on the precursor molecules to form the respective moiety or block in the copolymer. Thus, the moiety or block is derived from a precursor which is combined into the block copolymer, e.g. by condensation.

In a preferred embodiment, the graft block copolymer surfactant comprises a repeating copolymer subunit having the general structure:

Q. Q.

O O TJ TJ

3" .T O O ti^¬ CT ro (D

HydrophilB Backbone Hydrophile —

The graft block copolymer surfactant typically comprises from 2 to 20 copolymer subunits, preferably from 3 to 15 subunits, more preferably 3 to 10 subunits, especially 3 to 7 subunits. The number of subunits can be selected to achieve the desired property of the surfactant, in particular the viscosity.

The repeating copolymer subunit has more preferably the following structure:

The links between the subunits are shown as lines. This is because the nature of the link is not generally significant to the graft block copolymer surfactant. The person skilled in the art would select constituents with suitable complementary reactive groups, e.g. hydroxy groups and carboxylic acid groups, to allow the combination of subunits into the desired structure. In general, the links may be obtained via simple condensation reactions, e.g. between a PIBSA and a polyol, between a PIBSA and a PEG and between a PEG and a linker molecule, e.g. adipic acid. In the schematic structure given above, the link between the glycerol and PEG is achieved via the diacid head of PIBSA, and this forms a preferred means of linking the precursor.

In one aspect, the graft block copolymer surfactant may comprise the general structure:

R — - R

wherein A is the copolymer subunit described above and R represents a unit terminating the backbone of the copolymer. As mentioned above, n is preferably an integer from 1 to 19, preferably from 2 to 14, especially 2 to 6.

R may be essentially any moiety since its effects on the entire copolymer structure is generally insignificant. R may simply be the terminal group of the hydrophilic group. Where the hydrophilic block is a PEG, R may conveniently be a hydroxy group. However, particularly when the subunit A ends in a reactive group (e.g. as with the OH in PEG), it may be desirable or useful in many circumstances to introduce a chain terminating group to the end of the copolymer subunit. In this case, the moiety R is typically formed by the addition of a monovalent hydrocarbyl or substituted hydrocarbyl group. For example, a carboxylic acid is attached to an exposed hydroxy group of a PEG via an ester linkage. In this respect, any fatty carboxylic acid would be suitable. Preferred fatty acids include C₁₂ - C24 fatty acids, e.g. palmitic acid, oleic acid and linoleic acid. A particularly preferred fatty acid for combination with the surfactant is tall oil fatty acid (TOFA), a derivative of tall oil, which is primarily oleic acid. The graft block copolymer surfactant has a number average molecular weight of from 3000 to 70000, preferably from 8000 to 55000, more preferably from 8000 to 40000, and especially from 8000 to 25000. Generally, a metal working lubricant composition according to the present invention comprising the graft block copolymer surfactant will comprise a range of copolymer chains of different lengths such that there will be a range of molecular masses in a particular composition. In such a case, it is desirable that a substantial portion of the surfactant molecules are within the abovementioned size ranges. The graft block polymer surfactant has preferably a number average molecular weight (M_n) of from 1000 to 4000, preferably 1200 to 3500, especially 1500 to 3000. A preferred weight average molecular weight (M_w) for the surfactant is from 6000 to 70000, preferably 9000 to 50000, and especially 9000 to 24000.

The graft block copolymer surfactant can be produced by (a) reacting a hydrophobic block precursor, a backbone moiety precursor, and a hydrophilic block precursor to from a copolymer subunit; and, subsequently, (b) by reacting the copolymer subunit and a linker moiety precursor. This method may optionally comprise as an additional step (c) reacting the graft block copolymer with the chain terminating agent. The production may conveniently be performed in two or more distinct reaction steps, wherein in subsequent steps materials are added to the reaction. A first step may involve a reaction to form a copolymer subunit, which is suitably continued until a desired amount of copolymer subunit is produced. In a second step the linker moiety precursor may be added and the reaction continued to allow the linker moiety to link copolymer subunits together. The second reaction is continued until the desired amount of graft block copolymer surfactant is formed.

The formation of the copolymer subunit may itself involve more than one step. For example, the reaction may involve the formation of an intermediate subunit comprising the hydrophobic block and the backbone moiety, to which the hydrophilic block is then added.

Accordingly, in one embodiment, the method of producing a graft block polymer surfactant, comprises the steps of (a) reacting the hydrophobic block precursor and the backbone moiety precursor to from a reaction product; (b) reacting the hydrophilic block precursor and the reaction product of step (a) to from a copolymer subunit; and (c) reacting the copolymer subunit and the linker moiety precursor to form a graft block copolymer surfactant. As mentioned above, the method may optionally comprise an additional step (d) of reacting the graft block copolymer surfactant with a chain terminating agent.

However, on the other hand, the production may be performed in a single step or single batch. In such a method, the hydrophobic block precursor, the backbone moiety precursor, the hydrophilic block precursor and the linker moiety precursor are all reacted at the same time. Accordingly, in another embodiment, the method of producing a surfactant comprise the step of (a) reacting the hydrophobic block precursor, the backbone moiety precursor, the hydrophilic block precursor and the linker moiety precursor to form a graft block copolymer surfactant. As mentioned above, the method may optionally comprise an additional step (d) of reacting the graft block copolymer surfactant with a chain terminating agent.

One example of suitable conditions for a single step or single batch reaction involves addition of the hydrophobic block precursor, backbone moiety precursor, hydrophilic block precursor and linker moiety precursor into a single pot and reaction at a temperature of between 160° to 240⁰C, preferably 190° to 220⁰C until an acid value of less than 10, preferably less than 7, especially less than 3 is achieved for the product graft block copolymer surfactant.

In a preferred embodiment, the method of producing the graft block polymer surfactant comprises the steps of (i) reacting a hydrophobic block precursor and a backbone moiety precursor in a suitable reactor under suitable conditions to form a first reaction product; (ii) reacting the first reaction product with a hydrophilic block precursor to form a copolymer subunit; (iv) reacting a linker moiety precursor with at least two copolymer subunits to form the graft block copolymer surfactant; and optionally (v) reacting the graft block copolymer surfactant with a chain terminating agent.

The graft block copolymer surfactant has a desired acid value of less than 10, preferably less than 7, more preferably less than 5 and especially less than 3.

According to a more preferred method, the hydrophobic block precursor is a hydrophobic hydrocarbyl substituted C4 - C₁₀ mono- and/or dicarboxylic acid producing material, the backbone moiety precursor is a nucleophilic compound and the hydrophilic block precursor is a polyvalent hydrophilic polymer having 2 - 6 functional groups. According to this method, the graft block polymer surfactant is obtainable by a process comprising :

(a) reacting a hydrophobic hydrocarbyl substituted C4 - C₁₀ mono- and/or dicarboxylic acid producing material and a nucleophilic compound having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups to form a first intermediate; and (b) reacting the first intermediate obtained in step (a) with a polyvalent hydrophilic polymer having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups, said polyvalent hydrophilic polymer having a M_n of300 - 5000; based on the total weight of the metal working lubricant composition.

The hydrophobic hydrocarbyl substituted C4 - C₁₀ mono- or dicarboxylic acid producing material and the nucleophilic compound having 2 - 6 functional groups are preferably reacted in amounts such that the molar ratio of carboxylic groups : functional groups is between 1 : 2 to 1 : 6, more preferably between 1 : 2 to 1 : 4 and most preferably 1 : 2 to 1 : 3. For example, if the hydrophobic hydrocarbyl substituted C4 - Cio mono- or dicarboxylic acid producing material is a polyisobutenyl succinic anhydride (PIBSA) that therefore can produce two carboxylic groups, the nucleophilic compound has preferably 2 - 6 functional groups, so that each carboxylic group is derivatised by the nucleophilic compound. Additionally, it is preferred that the first intermediate is reacted with a polyvalent hydrophilic polymer having 2 - 4 functional groups, more preferably 2 functional groups, selected from the group consisting of amine groups and hydroxy groups. The polyvalent hydrophilic polymer has preferably a M_n of 400 - 1000, more preferably of 400 - 800 and most preferably of 500 - 700. According to a preferred embodiment, the process further comprises a step (cl), wherein the product of step (b) - as a second intermediate - is reacted with a C₂ - C20 polycarboxylic acid producing material, preferably a C₂ - C₁₂ polycarboxylic acid producing material, said C₂ - C20 polycarboxylic acid producing material having the function of the linking moiety as disclosed above A particularly preferred C₂ - C20 polycarboxylic acid producing material is adipic acid. As will be apparent to the person skilled in the art, the polycarboxylic acid may occur in the form of an anhydride, an ester, an acid halide and the like.

According to another preferred embodiment, the process further comprises a step (c2), wherein the product of step (b) - as a second intermediate - is reacted with a Ci₂ - C₂4 fatty acid as chain terminating agent as is disclosed above. A particularly preferred fatty acid for combination with the surfactant according to the invention is tall oil fatty acid (TOFA), a derivative of tall oil, which is primarily oleic acid. According to another preferred embodiment, the process includes both steps (cl) and (c2), wherein these steps may be performed sequentially in any order or concurrently.

The hydrophobic hydrocarbyl substituted C4 - C₁₀ dicarboxylic acid producing material is preferably prepared by reacting a polyolefin having at least a terminal carbon carbon double bond, said polyolefin being obtained by polymerising a C₂ - C₁₀ olefin, with a monounsaturated C4 - C₁₀ dicarboxylic acid. Optionally, the polyolefin comprises a minor amount Of C₄ - Ci₂ diolefin such as butadiene, isoprene and divinyl benzene. Processes for preparing such hydrophobic hydrocarbyl substituted C4 - C₁₀ dicarboxylic acid producing material are well known in the art.

In a particularly preferred embodiment, the hydrophobic hydrocarbyl substituted C4 - Cio dicarboxylic acid producing material is suitably a polymer or copolymer of an C₂ - C₁₂ α-olefin, in particular the polymer or a copolymer of an α-olefin having from 2 to 6 carbon atoms as is disclosed above. A particularly preferred hydrophobic hydrocarbyl substituted C4 - C₁₀ dicarboxylic acid producing material is derived from a polyisobutenyl succinic anhydride (PIBSA) or an atactic polypropenyl succinic acid anhydride (above referred to as "atactic polypropylene succinic anhydride"; APOSA) having a molecular weight in the range of 300 to 5000, preferably 500 to 1500, wherein the polyisobutenyl succinic anhydride (PIBSA) or the atactic polypropenyl succinic acid anhydride (APOSA) may have 1 - 2 succinic anhydride moieties per polyisobutenyl or atactic polypropenyl chain.

According to the invention, the nucleophilic compound has 2 - 6 functional groups, preferably 2 - 4 functional groups, and is preferably selected from the group of C3 - C₁₂ hydrocarbyl compounds having 2 - 8 heteroatoms selected from the group consisting of O and N. Examples of these compounds include polyamines, amine alcohols and polyols. Polyols are particularly preferred nucleophilic compounds. Preferably, the polyol is represented by Formula (I):

(I)

wherein:

X is O or C; Q is H or linear or branched Ci - C₆ alkyl;

P is linear or branched Ci - C₆ alkylene;

R is H or linear or branched Ci - C₆ alkyl; p + q = 2 or 4; if X is O, then q = 0 and p = 2; ifX is C, then p = 2 - 4, q = 0 - 2, and p + q = 4;

S is linear or branched Ci - C₆ alkylene; r + s = 3; r = 0 or 1 ; and s = 2 or 3. Suitable alkyl groups are methyl, ethyl, n-propyl and the like. Suitable alkylene groups include methylene, ethylene, 1,3 -propylene, 1,2-propylene, 2 -methyl- 1,3- propylene and the like. Suitable examples of polyols include glycerol, neopentyl glycol, ditrimethylolpropane, diglycerol, ditrimethylolethane, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerthyritol, dipentaerthyritol, tripentaerthyritol and sorbitol. In a preferred embodiment the polyol is glycerol.

The polyol may also be a chain extended polymer of the polyols mentioned above. Also included are hyperbranched and dendritic polymers such as the Boltorn polymers that are manufactured by Perstorp AB, Sweden, in particular Boltorn H 4000 which has six terminal hydroxy end groups. Boltorn type polymers are disclosed in for example US 5.418.301, incorporated by reference herein. Suitable hyperbranched

(co)polymers are for example disclosed in US 5.663.247, incorporated by reference herein.

It is preferred that the polyvalent hydrophilic polymer is selected from the group consisting of the hydrophilic, preferably water soluble (preferably soluble in water to the extent of at least 5% by weight at 25°C), polymers or copolymers of a C₂ - C4 alkylene glycols disclosed above.

The process for preparing the graft block polymer surfactant comprises then the steps of: (a) reacting a hydrophobic hydrocarbyl substituted C4 - C₁₀ mono- or dicarboxylic acid producing material and a nucleophilic compound having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups to form a first intermediate; and

(b) reacting the first intermediate obtained in step (a) with a polyvalent hydrophilic polymer having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups, said polyvalent hydrophilic polymer having a

M_n of300 - 5000.

It is preferred that the hydrophilic hydrocarbyl substituted C4 - C₁₀ mono- or dicarboxylic acid producing material and the nucleophilic compound are reacted at from 100° to 140⁰C, preferably approximately 120⁰C. Typically a reaction time of 2 hours or more is suitable to obtain a desired level of reaction product, preferably 3 hours or more.

It is furthermore preferred that the first intermediate and the polyvalent hydrophilic polymer are reacted at from 180° to 250 ⁰C, preferably 190° to 230 ⁰C, especially 200° to 225°C. Optionally, a catalyst, e.g. titanium (IV) butanate (TnBT), may be added.

Additionally, it is preferred that steps (cl) and (c2) are carried out at from 180 ⁰C to 250 ⁰C, preferably 190 ⁰C to 220 ⁰C.

Suitably, the reaction is performed at atmospheric pressure under a blanket of a suitably inert gas, e.g. nitrogen.

The process according to the present invention may further involve an additional step (d) of adding a solvent to the graft block copolymer surfactant to reduce the viscosity.

The graft block copolymer can further be characterised as comprising the reaction products of at least the following components:

(I) a first intermediate comprised of the reaction products of a hydrophobic hydrocarbyl substituted C4 - C₁₀ mono- or dicarboxylic acid producing material and a nucleophilic compound having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups; and (II) a polyvalent hydrophilic polymer having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups, said polyvalent hydrophilic polymer having a M_n of 300 - 5000.

The graft block polymer surfactant according to the invention may be further characterised as comprising the reaction products of at least the following components:

(I) a first intermediate comprised of the reaction products of a hydrophobic hydrocarbyl substituted C4 - C₁₀ mono- or dicarboxylic acid producing material and a nucleophilic compound having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups;

(II) a second intermediate comoprised of the reaction products of the first intermediate and a polyvalent hydrophilic polymer having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups, said polyvalent hydrophilic polymer having a M_n of 300 - 5000; and

(III) a C₂ - C20 polycarboxylic acid producing material and/or a C₁₂ - C24 fatty acid.

Metal working lubricant composition

The present invention relates to a metal working lubricant composition comprising 0.05 to 30 % by weight of a graft block polymer surfactant, more preferably 0.1 to 10 % by weight and in particular 0.5 to 2 % by weight, based on the total weight of the metal working lubricant composition.

The graft block copolymer surfactant is able to form extremely stable metal working lubricant compositions, in particular compositions stable against inversion.

According to a preferred embodiment of the present invention, the metal working operation comprises a metal forming operation, a metal removing operation or both. Additionally, it is preferred that the metal forming operation comprises a cold rolling operation, a hot rolling operation or a drawing operation. Furthermore, it is preferred that the metal removing operation is selected from the group consisting of grinding, milling, cutting, turning and honing. As will be apparent to those skilled in the art, the metal working lubricant composition according to the present invention may comprise a blend of two or more different graft block polymer surfactants.

According to the present invention, the metal working lubricant composition may comprise additives such as extreme pressure additives, anti-wear additives, pour point depressants, anti-oxidants, other lubricating components and the like. The metal working lubricant composition may be in the form of an emulsion or an aqueous dispersion. Such emulsions or aqueous dispersions can be broken by adding a polymeric, preferably a cationic, flocculating agent. A preferred method for breaking the metal working lubricant composition is to add an aqueous solution of the polymeric cationic flocculating agent, e.g. Magnafloc® LT 22S available from Ciba Specialty Chemicals Inc., to the metal working lubricant composition. Preferably, the amount of the polymeric cationic flocculating agent that is added is such that a concentration of about 10 - 100 ppm, preferably about 40 - 60 ppm, of the polymeric cationic flocculating agent is obtained within the metal working lubricating composition. In a subsequent step, the pH of the metal working lubricating composition is raised to about 7.

It is preferred that the metal working lubricant composition comprises a hydrophobic lubricating agent, preferably an oil, e.g. a mineral oil and/or a natural oil or fat, in an amount of 0.05 to 35 % by weight, preferably 0.10 to 15 % by weight and in particular 0.5 to 5 % by weight, based on the total weight of the metal working lubricant composition.

Examples

Example 1 - Manufacture of a the graft block copolymer surfactant

The following method is suitable for the formation of a graft block copolymer surfactant according to the present invention. The method detailed is suitable for production in a 200 kg batch reactor, but the method is amenable to scale up.

Glissopal® SA is commercially available from BASF. It is a clear, amber, highly viscous liquid having a density according to DIN 51757 of 0.920 kg/m³ at 20⁰C, a viscosity according to DIN 51562 of 27900 mm /s at 40⁰C and a saponification number of 87 mg KOH/g. It is based on a chlorine free highly reactive polyisobutene having a M_n of 1000. The level of bismaleination is 9%

The PIBSA and PEG are preheated to 50 ⁰C.

A clean and dry reactor is set to heat to 50 ⁰C. - The PIBSA is charged and a nitrogen blanket is applied.

The glycerol is then added and the temperature increased to 120 ⁰C.

The temperature is held for 4 hours.

The mixture is analysed by infra-red (IR) to determine if the reaction has reached the desired end point. The end point is indicated by the disappearance of an anhydride peak which is at 1770 cm^"1 Typically this peak will be reduce to 1% of its initial pre-reaction intensity as measures by a peak area measurement.

If the specification is not reached then the reaction is continued for 2 hours and reassessed. This is continued until the desired specification is reached (e.g. the anhydride peak disappears) or there is no further reduction in the anhydride peak. - The PEG is then added to the reactor and the temperature increased to 220 ⁰C.

When the reactor temperature is over 150 ⁰C the TnBT is added.

The temperature is held for 4 hours.

The mixture is analysed to assess the acid number determine if the reaction has reached the desired end point. The acid number is ideally as low as possible, with a value of 0.3 mg KOH/g being the upper limit in this example. - If the specification is not reached then the reaction is continued for 1 hour and reassessed. This is continued until the desired specification is reached.

- The reactor is then cooled to 120 ⁰C and the adipic acid charged.

- The reactor is then heated to 220 ⁰C. If required the catalyst may be replaced. - The temperature is held for 5 hours.

- The mixture is analysed to assess the acid number to determine if the reaction has reached the desired end point. A suitable end point is indicated by an acid value of 3 or less.

- If the specification is not reached then the reaction is continued for 1 hour and reassessed. This is continued until the desired specification is reached.

- Once the specification is reached the reaction is complete.

- The temperature is then reduced to 120 ⁰C, and a suitable ester is introduced to reduce the viscosity of the composition for easier storage or movement, e.g. barrelling. Suitable esters are marketed under the trade name Priolube, available from Uniqema.

The product of the reaction is an extremely viscous, tar-like lubricant composition. Typically giving a viscosity of <800 cP at 75°C.

Analysis of the product of the reaction reveals that the composition contains a mixture of polymer molecules of different sizes, with an M_w of around 15.000 and an M_n of around 2500.

Example 2 - Metal working lubricant composition

Water soluble metal working lubricant compositions were prepared by adding 0.6 % by weight of the graft block polymer surfactant to compositions comprising the following components in the indicated ranges:

- (Partial) polyol ester 20 - 70 wt%

- Natural oil/fat 0 - 20 wt%

- Mineral oil 20 - 50 wt% - Antioxidant 0.1 - 1 wt%

- Anti- wear/extreme pressure additives 0.5 - 2 wt%

- Emulsifier(s) 1 - 6 wt% By the term "(partial) polyol ester" is meant a fully esterified polyol which may comprise a small amount (usually about 0.1 to about 10 % by weight) of free OH- groups that are not converted in the esterification reaction.

Claims

1. A metal working lubricant composition comprising 0.05 to 30 % by weight of a graft block polymer surfactant, based on the total weight of the metal working lubricant composition, said graft block polymer surfactant having an number average molecular weight of 3000 to 70000 and having a backbone comprising a backbone moiety, hydrophobic blocks having a number average molecular weight of at least 300, and hydrophilic blocks having a number average molecular weight of at least 300, wherein the hydrophobic blocks project substantially in their entirety from the backbone to form grafts, and wherein the hydrophilic blocks form at least part of the backbone in conjunction with the backbone moiety or project substantially in their entirety from the backbone to form grafts, or a mixture of the two.

2. Metal working lubricant composition according to Claim 1, comprising 0.05 to 30 % by weight of a graft block polymer surfactant obtainable by a process comprising by:

(a) reacting a hydrophobic hydrocarbyl substituted C4 - C₁₀ mono- or dicarboxylic acid producing material and a nucleophilic compound having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups to form a first intermediate; and

(b) reacting the first intermediate obtained in step (a) with a polyvalent hydrophilic polymer having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups, said polyvalent hydrophilic polymer having a M_n of 300 - 5000, based on the total weight of the metal working lubricant composition.

3. Metal working lubricant composition according to Claim 2, wherein the process further comprises a step (cl), wherein the product of step (b) is reacted with a C₂ - C20 polycarboxylic acid producing material.

4. Metal working lubricant composition according to Claim 2 or Claim 3, wherein the process further comprises a step (c2), wherein the product of step (b) is reacted with a C₁₂ - C24 fatty acid.

5. Metal working lubricant composition according to any one of Claims 2 - 4, wherein the hydrophobic hydrocarbyl substituted C4 - C₁₀ dicarboxylic acid producing material is prepared by reacting a polyolefϊn having at least a terminal carbon carbon double bond, said polyolefin being obtained by polymerising a C₂ - Cio olefin, with a monounsaturated C4 - C₁₀ dicarboxylic acid.

6. Metal working lubricant composition according to Claim 5, wherein the polyolefϊn is selected from the group of polyisobutenes and atactic polypropenes.

7. Metal working lubricant composition according to any one of Claims 2 - 6, wherein the nucleophilic compound having 2 - 6 functional groups is selected from the group of C3 - C₁₂ hydrocarbyl compounds having 2 - 8 heteroatoms selected from the group consisting of O and N.

8. Metal working lubricant composition according to any one of Claims 2 - 7, wherein the polyvalent hydrophilic polymer is selected from the group consisting of polymers or copolymers of a C₂ - C4 alkylene glycol.

9. Metal working lubricant composition according to Claim 8, wherein the polyvalent hydrophilic polymer is a polyethylene glycol.

10. Metal working lubricant composition comprising 0.05 to 30 % by weight of a graft block polymer, based on the total weight of the metal working lubricant composition, wherein the graft block copolymer surfactant comprises the reaction products of at least the following components:

(a) a first intermediate comprised of the reaction products of a hydrophobic hydrocarbyl substituted C4 - C₁₀ mono- or dicarboxylic acid producing material and a nucleophilic compound having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups; and

(b) a polyvalent hydrophilic polymer having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups, said polyvalent hydrophilic polymer having a M_n of 300 - 5000.

11. Metal working lubricant composition according to Claim 10, wherein the graft block polymer surfactant comprises the reaction products of at least the following components: (a) a first intermediate comprised of the reaction products of a hydrophobic hydrocarbyl substituted C4 - C₁₀ mono- or dicarboxylic acid producing material and a nucleophilic compound having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups; (b) a second intermediate comoprised of the reaction products of the first intermediate and a polyvalent hydrophilic polymer having 2 - 6 functional groups selected from the group consisting of amine groups and hydroxy groups, said polyvalent hydrophilic polymer having a M_n of 300 - 5000; and

(c) a C₂ - C20 polycarboxylic acid producing material and/or a Ce - C24 fatty acid.

12. A metal working lubricant composition according to any one of Claims 1 - 11, further comprising a hydrophobic lubricating agent in an amount of 0.05 to 35 % by weight, based on the total weight of the metal working lubricant composition.

13. Use of a metal working lubricant composition according to any one of Claims 1 - 12 in metal working operations.

14. Use of a metal working lubricant composition according to any one of Claims 1 - 12 in metal removing operations.

15. A method of breaking the metal working lubricant composition according to any one of Claims 1 - 12, said method comprising the addition of a polymeric flocculating agent.

16. Method according to Claim 15, wherein the polymeric flocculating agent is a polymeric cationic flocculating agent.