Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2001-06-12
2002-11-19
Rotman, Alan L. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C560S199000
Reexamination Certificate
active
06482975
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to novel bis-poly(ethylene oxide) oligomeric surfactants, to a process for their production and to their use as antistats for photographic coatings.
BACKGROUND OF THE INVENTION
It is known in the art to include a surfactant in photographic coatings in order to impart antistatic properties. The use of nonionic fluorosurfactants based on poly(ethylene oxide) is disclosed in U.S. Pat. Nos. 4,582,781 and 4,610,955. A typical nonionic fluorosurfactant of this kind is commercially available under the trade name Zonyl FSN and has the following linear chemical structure
C
x
F
2x+1
(CH
2
)
y
—(CH
2
CH
2
O)
z
—OH
in which x varies from approximately 4 to 14 but is about 8 on average; y is 2; and z is a distribution of numbers with an average of about 10.
However, it would be an advance in the art if surfactants could be provided that were easier to dissolve in water than the nonionic fluorosurfactants typified by Zonyl FSN and yet which exhibited more surface activity or hydrophobicity.
SUMMARY OF THE INVENTION
The present invention, in one of its aspects, provides the compounds of the general formula
in which
R is an alkyl group with 10-20 carbon atoms, an alkenyl group with 10-20 carbon atoms or a fluoroalkyl or fluoroalkenyl group with f carbon atoms that each bear at least one fluorine atom and g carbon atoms that bear only hydrogen atoms, in which 1.5f+g=10-20 and g may optionally be zero,
R′ is an alkyl group with 1 to 4 carbon atoms,
L is a linking group, a linking atom or a chemical bond, and
p is at least 2, q is at least 2 and p+q=from 4 to 100.
In another of its aspects, the present invention also provides a process for the production of an optionally substituted alkyl poly(ethylene oxide), which process comprises the steps of (1) reacting maleic anhydride with a poly(ethylene glycol) alkyl ether of the general formula
R′O(CH
2
CH
2
O)
p
H (2)
and/or with a poly(ethylene glycol) alkyl ether of the general formula
R′O(CH
2
CH
2
O)
q
H (3)
in which
R′, p and q have the meanings stated above,
and (2) reacting the product of step (1) with a compound of the general formula
RL′H (4)
in which
R has the meaning stated above, and
L′ is a linking group or linking atom.
In a further aspect, the present invention also provides a process for the production of an optionally substituted alkyl poly(ethylene oxide) in which a compound of the general formula
in which
R and L have the meanings stated above is reacted with a compound of the general formula
R′O(CH
2
CH
2
O)
p
H (2)
and/or with a compound of the general formula
R′O(CH
2
CH
2
O)
q
H (3)
in which
R′, p and q have the meanings stated above.
In yet another of its aspects, the present invention further provides a photographic element comprising a substrate and a coating on the substrate, wherein the coating contains a compound of the formula (1) above or a compound that has been prepared by a process of this invention. The present invention also provides a layer of gelatin that contains a compound of the formula (1) or a compound prepared by a process of this invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
The compounds of the present invention, which may be classified as alkyl poly(ethylene oxides), are represented by the general structure (
1
) given above. In that structure, R is preferably an alkyl group of the formula C
k
H
2k+1
, an alkenyl group of the formula C
j
H
2j−1
or a fluoroalkyl group of the formula C
n
F
2n+1
—(CH
2
)
m
, or a corresponding fluoroalkenyl group, wherein k, j or (n+m) are equivalent to 10 to 20 carbon atoms (e.g. CH
3
and CH
2
), given the premise that 1 fluorinated carbon (e.g. CF
3
or CF
2
) equates to 1.5 hydrocarbon carbons. In certain preferred embodiments, R is selected from alkyl groups having from 10 to 20 carbon atoms, alkenyl groups having from 10 to 20 carbon atoms and fluoroalkyl groups of the general formula C
n
F
2n+1
(CH
2
)
m
wherein the sum of (1.5n)+m is from 10 to 20. The definition of n and m is based on the premise that one fluorinated carbon (e.g. CF
3
or CF
2
) equates to 1.5 hydrocarbon carbons (e.g. CH
3
or CH
2
) in hydrophobic terms (from comparisons of critical micelle concentrations between alkyl and fluoroalkyl surfactants containing the same hydrophilic group; see E. Kissa,
Fluorinated Suactants, Surfactant Science Series
, Vol.50, Marcel Dekker (1994), 227-228). Preferably, a fluoroalkyl or fluoroalkenyl group R will be attached to the succinic acid moiety by a fluorinated carbon atom (as, for instance, when m=zero) only when L is a single chemical bond.
Although, in principle, the hydrophobic group R may be branched, it is currently preferred that R be a straight-chain group, because systems with straight hydrophobic tails are cheaper to produce. The hydrophobic group R is linked to the succinate moiety by L, which may be a linking group, such as —NH—, or linking atom, such as —S—, or simply a chemical bond, in particular a single or sigma (&sgr;) chemical bond.
Preferably, R′ denotes a methyl, ethyl, n-propyl or isopropyl group. More preferably it denotes a methyl group. The R′ groups in formulae (2) and (3) may be the same or different.
In the general structure (1), p and q, which may be the same or different, may vary but preferably p+q =from 8 to 50, more preferably from 8 to 32. In certain preferred embodiments; p and q are selected so as to balance the hydrophobic group in such a manner as to produce a soluble surfactant with a low critical micelle concentration, typically of the order of 10
−3
M (molar) or less, preferably 10
−4
M (molar) or less. In certain preferred embodiments, p and q denote the same number.
It will be appreciated, however, that the general formula (I) extends not only to individual compounds of the stated structure but also to mixtures of two or more compounds having the stated structure. In such mixtures, p and q may refer to average values.
As noted above, the compounds of the present invention may be prepared by a process in which maleic anhydride is reacted with a poly(ethylene glycol) alkyl ether, and the resultant polyethylene glycol diester of maleic acid is thereafter reacted with a compound of the general formula RL′H in which R and L′ are as defined above. The reaction of the maleic anhydride with the poly(ethylene glycol) alkyl ether is generally carried out in the presence of an acid catalyst, for example sulphuric acid. The diester, which constitutes an intermediate product, may be isolated prior to further reaction. The diester intermediate product is generally reacted with the compound RL′H in the presence of a basic catalyst, for example potassium carbonate. In certain preferred embodiments, the compound of the formula RL′H is a thiol of the formula RSH, in which case the end product may be classified as an alkyl-, alkenyl-, or fluoroalkyl- or fluoroalkenyl-thiosuccinic acid, polyethylene glycol diester.
In either of the preparative processes the poly(ethylene glycol) alkyl ether may be a single compound but will usually be a mixture of such compounds having different ethoxy chain lengths. Thus the resultant product of the formula (I) will contain compounds having different chain lengths in the two ethoxy chains. It is possible to introduce the different ether groups sequentially: the first ethoxylate can be added to the anhydride to give a half ester, the remaining chain length can then be transformed into the acid chloride and the second chain can then be added under basic conditions; this may be useful if p and q are to be different. Another possibility is to fractionate a mixture of products of the formula (1).
The synthesis of fluoroalkyl, alkyl, fluoroalkenyl or alkenyl derivatives according to the first preparative process may be illustrated by the following reaction scheme (Scheme 1):
In reaction Scheme 1, p =
Pitt Alan R.
Wear Trevor J.
Reyes Hector
Wells Doreen M.
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