Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Compound of indeterminate structure – prepared by reacting a...
Reexamination Certificate
2000-07-06
2002-10-08
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Compound of indeterminate structure, prepared by reacting a...
C508S268000, C508S284000, C508S404000, C508S551000
Reexamination Certificate
active
06462000
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the use of polymers containing structural units of N-vinyl acyl compounds and acrylamidosulfonic acids to suppress the misting of water-based
In metalworking, cooling lubricants are generally used in order to reduce tool wear. At the high tool or workpiece speeds involved, for example, in the cutting or grinding of metals, these lubricants may be thrown up into the environment, causing unwanted misting. The prior art has disclosed a variety of approaches to reducing this misting.
EP-A-0 811 677 discloses water-based metalworking fluids which comprise antimisting copolymers. These copolymers consist firstly of structural units derived either from acrylamidosulfonic acids or sulfonated styrene and secondly of acrylamide or acrylate structural units.
EP-B-0 642 571 discloses the use of polymers having a molecular weight of more than 1,000,000 units as antimisting additives, the polymers being selected from the group consisting of polyalkylene oxides, polyacrylamides, polymethacrylamides or acrylamide-methacrylamide-unsaturated carboxylic acid copolymers.
GB-A-22 52 103 discloses an antimisting additive comprising polymers composed of structural units derived from water-soluble acrylamides, acrylic acid and water-insoluble acrylamides.
SUMMARY OF THE INVENTION
Additives for reducing the misting in metalworking are an important aid not least for reasons of protecting the health of the persons who carry out such work. Consequently, additives of this kind are the subject of intense research and development effort. The object on which the present invention is based is to provide additives having improved properties.
It has surprisingly been found that polymers based on N-vinyl acyl compounds and acrylamidosulfonic acids are highly effective mist suppressants.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention provides for the use of copolymers containing structural units derived from the compounds of the formulae 1 and 2
in which
R
1
and R
2
are H, C
1
-C
4
alkyl or, with inclusion of the N—CO— group, form a ring of 5, 6, 7 or 8 ring atoms which in addition to the N—CO— group may include further heteroatoms,
R
3
is H or C
1
-C
4
alkyl,
R
4
is a branched or unbranched C
1
-C
6
alkylene radical, and
Y is an alkali metal or ammonium
in amounts of from 0.01 to 2% by weight to prevent misting in water-based cooling lubricants.
The copolymer thus defined is also referred to below as antimisting additive. The phrase “derived from” denotes in this case that the stated olefinically unsaturated compounds, in reacting, lose at least one C—C double bond and the copolymer therefore contains corresponding structural units.
The invention further provides water-based cooling lubricants comprising these antimisting additives.
In formula (1), R
1
and R
2
are H or C
1
-C
4
alkyl. In addition R
1
and R
2
may, with inclusion of the —N—CO— group, form a ring having 5, 6, 7 or 8 ring atoms. Preference is given to rings having 5, 6 or 7 ring atoms. R
1
and R
2
may include heteroatoms. In one preferred embodiment they comprise only carbon atoms. In one particular preferred embodiment formula 1 represents a structural unit of the formula 1a.
In another particularly preferred embodiment, formula 1 represents N-vinylcaprolactam. In another particularly preferred embodiment the structural unit is of the formula 1b.
R
3
is preferably hydrogen. In one preferred embodiment R
4
is an alkylene radical of the formula 3.
The structural unit of the formula 2 is preferably prepared by the copolymerization of acrylamidopropenylsulfonic acid (AMPS).
Preferred molecular weights (number average) of the copolymers are between 100,000 and 2,000,000, in particular from 250,000 to 1,000,000 units.
Indicators used for the molecular weight are the relative viscosity and/or the k value. To determine the k value, the copolymer is dissolved in a defined concentration (usually 0.5%) and the efflux time at 25° C. is determined using an Ubbelohde capillary viscometer. This gives the absolute viscosity of the solution (&eegr;
c
). The absolute viscosity of the solvent is &eegr;
o
. The ratio of these two absolute viscosities gives the relative viscosity
z
=
η
c
η
o
and from the relative viscosity and the concentration function the k value can be determined using the following equation:
Lg
z
=
(
75
·
k
2
1
+
1.5
kc
+
k
)
c
In one preferred embodiment the molar amounts of the structural units of the formulae 1 and 2 add up to 100% by weight.
In another preferred embodiment the copolymer contains from 2 to 50% by weight of the structural units derived from formula 1. In addition, the copolymer contains preferably from 50 to 98% by weight of structural units of the formula 2, in particular from 20 to 35% by weight of structural units of the formula 1 and from 65 to 80% by weight of structural units of the formula 2.
In another preferred embodiment, however, the copolymer may contain further comonomers. In another preferred embodiment of this kind the copolymer contains structural units derived from compounds of the formula 4
Independently of one another, R
5
and R
6
are H or C
1
-C
4
alkyl. The fraction of structural units of the formula (4) in the copolymer is up to 15% by weight, preferably from 5 to 15% by weight.
In another preferred embodiment the polymer contains up to 60% by weight of structural units derived from compounds of the formula 5
in which
R
7
and R
8
independently of one another are a terminally unsaturated alkenyl radical having 3 to 5 carbon atoms,
R
9
and R
10
independently of one another are C
1
-C
4
alkyl, and
X is an anion.
R
7
and R
8
are preferably both an allyl radical.
In a further preferred embodiment the copolymer contains 5-20% by weight of structural units derived from acrylic acid.
Possible anions X are those which do not have a disruptive influence on the polymerization. Examples of anions are halides, sulfates, nitrates, carbonates, and phosphates.
The copolymers of the invention can be prepared by copolymerizing compounds of the formulae (1) and (2) and, if used, (4) and/or (5). The process for preparing the copolymers is described in the prior art and is set out below.
The copolymers can be prepared by the technique of solution polymerization, bulk polymerization, emulsion polymerization, inverse emulsion polymerization, precipitation polymerization or gel polymerization. The polymerization is preferably performed as a solution polymerization in water or as a precipitation polymerization.
When carrying out the copolymerization in a water-miscible organic solvent, it is generally carried out under the conditions of precipitation polymerization. In this technique the polymer is obtained directly in solid form and can be isolated by distilling off the solvent or by filtration with suction and drying.
Suitable water-miscible organic solvents for carrying out this preparation process are, in particular, water-soluble alkanols, namely those having 1 to 4 carbon atoms such as methanol, ethanol, propanol, isopropanol, n-, sec- and isobutanol, but preferably tert-butanol.
The water content of the lower alkanols used as solvent in this case should not exceed 6% by weight, since otherwise lumps may form during the polymerization. It is preferred to operate with a water content of from 0 to 3% by weight.
To a certain degree, the amount of solvent to be used depends on the nature of the comonomers employed. In general, from 200 to 1000 g of solvent are used per 100 g of total monomers.
When conducting the polymerization in inverse emulsion, the aqueous monomer solution is emulsified in a known manner in a water-immiscible organic solvent such as cyclohexane, toluene, xylene, heptane or high-boiling petroleum fractions with the addition of from 0.5 to 8% by weight, preferably from 1 to 4% by weight, of known emulsifiers of the W/O type and this emulsion is polymerized using conventional free-radical initiators.
The principle of inverse emulsion polymerization is known from U.S.
Heier Karl Heinz
Kupfer Rainer
Clariant GmbH
Howard Jacqueline V.
Silverman Richard P.
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