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Description  |
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THE PRIOR ART
This invention, while of a broad nature, is of particular interest in
connection with the foaming of unsaturated polyesters. There are several
references in the literature to methods proposed for foaming polyester
resins, but to a large extent the proposed literature methods were carried
out using complex mixtures of components in aqueous systems. Moreover,
many of them relate to a sequential operation in which one first releases
gas to the polymerizable/cross-linkable resin medium following which one
attempts to effect polymerization/cross-linking without destroying the
foam. The difficulties involved in such a technique are manifest. One must
attempt to correlate the foaming operation and the further
polymerization/cross-linking operation. Such operations have been found to
be entirely impracticable. It has also been attempted in the prior art to
produce foams by initiating polymerization/cross-linking while gas is
being released to the resinous medium. This too has proved to be entirely
impracticable. Where one attempts to perform such prior art operations in
such a manner that the release of gas and the initiation of
polymerization/cross-linking is substantially simultaneous, the
polymerization/cross-linking reaction takes place so quickly that the
resin medium becomes too highly viscous or even rigid at such an early
stage that the resin cannot be foamed. In the case where the operation is
performed sequentially, the foam is a transitory nature; i.e. the foam
dissipates, to the extent that the gas is released to the atmosphere,
before polymerization/cross-linking is effected.
While the well-known azo blowing agents, such as azodicarbonamide,
decompose into gaseous products upon heating, they do not act concurrently
as a polymerization initiator, and the incorporation of a separate
initiator is required to support the foam. Addition of a separate gelling
agent presents the problem of coordinating the polymerization of the resin
with the release of the gas from the blowing agent. Furthermore,
azodicarbonamide as a blowing agent requires too high a temperature for
use with polyesters. In the case of normal azo initiators, such as azo
nitriles, the curing of the polyester system develops so rapidly that the
gas released does not have any opportunity to expand.
In the process of the present invention, the azo compounds react with the
resin media in a fortuitously coordinated manner to both release gaseous
products and initiate polymerization and/or cross-linking of the resin
media. Thus, the azo compounds are activated by an acidulous or acidic
polymerizable medium (as defined hereinafter) to gel the resulting resin
while the gas is liberated. In view of the coordinated reactions, the
resin medium expands while resin gelling occurs, forming a cell structure.
The present invention while not limited thereto, is especially useful in
the preparation of foamed polyester resins, both rigid and flexible.
Cellular structures formed from polyesters are relatively strong and
inexpensive, generally resistant to heat and chemicals and exhibit good
light stability and minimal moisture pickup. Cellular polyester structures
are not commercially available due to the difficulty discussed above, i.e.
coordination of gas generation and resin solidification. The present
invention presents a simple and effective answer to that problem.
STATEMENT OF THE INVENTION
This invention relates to shaped cellular structures formed from mediums
which are polymerizable and/or cross-linkable by free radical initiation
to either a thermoplastic or thermosetting solid, to a process for
production of such structures and to the composition useful to form the
solid. The process comprises preparing the composition by mixing an acid
sensitive azo compound with an acidulous or acidic polymerizable medium at
a temperature below that at which during the mixing cycle, neither
substantial thermal decomposition of the azo compound nor substantial
cross-linking or further polymerization of the medium normally occurs;
after mixing the composition is permitted to foam into a resinous cellular
structure of the desired shape (as used herein, being "permitted to foam"
denotes decomposition of a portion of the azo compound to effect
liberation of gas and simultaneous use of another portion of the azo
compound to effect cross-linking and/or further polymerization of the
resulting resin).
DEFINITIONS
By "acid sensitive azo compounds" as broadly used in the instant invention
is meant those mono- and poly- azo compounds containing the group
##STR2##
wherein Y is a monovalent or divalent acid sensitive group which in the
presence of an acidulous or acidic polymerizable medium causes sufficient
decomposition of the azo compound to release gas in the medium while said
mono- or poly- azo compounds also promote polymerization and/or
cross-linking of the medium to provide a matrix that is sufficiently
polymerized and/or cross-linked that the generated gases cause the matrix
to expand (this state of polymerization and/or cross-linking is commonly
known, and is referred to hereinafter, as the "gelled" state), the
remaining valences in FORMULA I being satisfied by organic radicals;
provided that any carbon atom that is directly linked to an azo nitrogen
(except that of a carbonyl group) has at least two of its remaining three
valences satisfied by a carbon to carbon bond or a carbon to hydrogen
bond.
Particular acid sensitive groups (Y) include halogens, groups having an
oxygen or sulfur atom linked to the carbon atom shown in FORMULA I (such
as hydroxyl, ester, ether, cyanate, thiocyanate, sulfonyl groups), and
groups linked to the carbon atom shown in FORMULA I by a nitrogen atom
(such as urea derivatives, hydrocarbyl-oxa(or thia)amides (or
thio-amides), amines, isocyanates, and isothiocyanates).
By the term "polymerizable medium" is meant the fluid phase with which the
acid sensitive azo compound is mixed. It is essential that one component
in this medium be polymerizable or cross-linkable by free radical
initiation, i.e. the component is a resin polymerizable or cross-linkable
by free radical initiation ("reactive resin") or is a vinyl or vinylidene
monomer. Thus the medium may be conveniently classified as any of the
following Medium Systems Types A, B, C, D or E (exemplified in greater
detail hereinafter):
Medium A: A reactive polymeric resin, or mixture of reactive resins, or a
mixture of a reactive polymeric resin (or resins) with an unreactive resin
or resins.
Medium B: Reactive resin(s) and/or unreactive resin(s) dissolved and/or
dispersed in a polymerizable monomer or mixture of monomers.
Medium C: A reactive resin or mixture of resins at least one being
reactive, dissolved or dispersed in an inert solvent or diluent.
Medium D: A monomer or mixture of monomers.
Medium E: Combinations of any or all of the above.
Many of the physical properties of the resultant foams will depend on the
nature of the polymerizable medium in a manner well understood by those
skilled in the art. Also, the number and spacing of cross-linkable
functions in the resin will affect the degree of rigidity or flexibility
of the cured foamed product as is well known to those skilled in the art.
A wide variety of inert liquid diluents may be added to any of the above
described polymerizable media to give appropriate viscosity, physical
properties and/or cost.
By the term "acidulous" polymerization medium is meant that the
polymerization medium without added extraneous acid, contains a detectable
acid number. As will be discussed in greater detail hereinafter, some azo
compounds are sufficiently acid sensitive that the resin media needs only
to be acidulous to provide azo activation. Resins containing free-acid end
groups, such as polyesters, will frequently suffice without the need to
supply extraneous acid. For example, the alpha-hydroxyazo compounds hereof
wherein Y is OH and R.sup.7 is not H (of FORMULA II, hereinafter) are
sensitive enough that the acidity of the polyester resin alone, with no
extraneously added acid, is sufficient to activate their decomposition.
By the term "acidic" polymerization medium is meant a medium to which
extraneous acid has been added to promote azo decomposition. When addition
of extraneous acid becomes necessary because of the nature of the resin
media or the azo compound, a wide range of acids may be employed. In
general, for the more highly acid sensitive azo compounds relatively weak
acids are suitable whereas for the less acid sensitive azo compounds
strong acids are often necessary.
By the term "activator" as used herein is meant a compound which may be
added to the polymerizable medium to effect activation of acid sensitive
compounds so as to permit foaming of the polymerizable medium. Both
organic and inorganic Bronsted-Lowry acids (substances which will
dissociate a proton) and acylalkylsulfonyl peroxides have been found
useful for this purpose. An activator can be used to form an "acid"
polymerization medium or to increase the decomposition of the azo compound
during foaming of any polymerizable medium. Among the acylalkyl sulfonyl
peroxides, particularly effective are acylalkyl (cycloalkyl-)sulfonyl
peroxides having the general structure:
##STR3##
where n= 1 or 2, R' is lower alkyl of 1 to 6 carbons, or (where n= 2)
lower alkylene of 1 to 6 carbons, R" is secondary and tertiary alkyl of 4
to 20 carbons and cycloalkyl (including bicycloalkyl) of 5 to 10 carbons
which can be optionally substituted by inert substituents such as
chlorine, cyano, lower acyloxy or lower alkoxycarbonyl.
PROCESSING CONDITION
The foregoing structural characterizations coupled with the concept of
using any compound having such structure in an acidulous or acidic resin
medium constitutes the critical aspects of the invention. So long as a
monoazo or poly-azo compound have the structure as set forth hereinabove,
and so long as that they are combined with an acidulous or acidic resin
medium, one may successfully effect foaming of said resin. A wide range of
processing conditions, shaping techniques and after-treatments may be
used. In general, and broadly stated in the process of the present
invention, the azo compounds are activated to decompose and generate
gaseous products at room temperature or below upon contact with the
polymerizable medium to provide foamed polymeric structures. The mixture
of resin media and azo compound is shaped while the azo compound reacts
with the resin medium (a) to blow it by gas generation and (b) to initiate
polymerization of at least one component of the medium to provide a
partially polymerized or partially cross-linked matrix, i.e. a matrix
having fluidity characteristics such that the gases generated cause the
matrix to expand, thereby to define a stable foam. The gas bubbles,
dispersed through the gelled matrix, produce either a "closed" or "open"
cellular configuration depending upon the amount and rate of evolution of
the gas and the fluidity and strength characteristics of the resin medium
during the period of gas generation. After shaping, the cellular structure
can be cured. Depending upon the nature of the polymerizable medium
involved, such curing can involve cross-linking and/or further
polymerization. The use of an added curing agent (i.e. in addition to the
acid-sensitive azo foaming agent) is optional; in some formulations it
will improve the physical properties of the foamed structures.
Thus in the process of the present invention, the physical environmental
conditions of temperature and pressure, the manipulative techniques and
equipment employed in mixing components and the shaping of the cellular
structure during or after its production as well as after-treating by
curing, and the like, may vary widely. Some such variables are discussed
in greater detail below for illustrative purposes.
AMOUNT OF AZO TO USE
The amount of acid sensitive azo compound to be added to a particular resin
medium will depend upon the effect desired, and chemical identity of each
of the azo, the resin, and the extraneous acid or other activator (if
used) and the temperature at which the components are mixed. Obviously, a
lesser amount of a particular azo compound will produce, in an otherwise
identical system under the same conditions, a higher density product than
a relatively larger amount. Whether the cells will be closed or open will
depend both on the amount of azo used, the strength characteristics of the
resin during the expansion process, and the like. These are variables
within the skill of technicians versed in the art of blowing plastics.
Usually the use of sufficient azo to provide from 0.5 to 4 weight percent
based on total reactant is sufficient to form closed cell structures. As
little as 0.2 weight percentage will often produce observable foaming. As
much as 15 weight percentage of azo has been found useful in some systems.
Generally from about 0.2 to 8 weight percentage of azo may be used
effectively.
MIXING TECHNIQUES
Any conventional mixing method can be used to distribute the azo compound
throughout the resin medium, and any high speed paddle mixer is suitable.
Mixing nozzles for combining the two liquids may also be employed. The
order of addition of the reactants is not critical and may be varied for
particular purposes. However, it is usually preferable that the resin
medium contains whatever acid is necessary and whatever curing agent is
desired prior to the incorporation of the azo compound. The azo compound
can be mixed with monomer such as styrene and the latter mixture added to
the acidulated resin to facilitate processing.
TEMPERATURE VARIATION
The temperature at which the azo compound is mixed with the resin medium is
usually not important provided it is low enough to avoid rapid premature
polymerization of the resin medium. Operative temperatures depend upon the
nature of the azo compound and the resin. In general, the mixing should be
performed at a temperature not exceeding that which would be normally used
when the azo compound is employed for polymerization without an activator.
Generally, the reaction will occur at room temperatures, and the speed of
reaction at such temperatures will usually be suitable. The use of lower
or higher temperatures may be preferred.
OPTIONAL ADDITIVES: MEDIUM
The density of the foamed product structure can be controlled by the amount
and identity of azo compound employed, as pointed out previously. In
addition, the amount of foaming and hence the density of the final
cellular structure, can be augmented by the use of gases or liquids in the
resin medium which have boiling points such that the liquids vaporize
during either blowing or cure reactions. Liquids or gases of this class
generally exhibit significant vapor pressure below the curing
temperatures.
At times, it is advantageous to increase the flowability of the
polymerizable medium by addition of an unreactive diluent or solvent. It
has also been found useful to add surfactants to the resin medium to
promote uniformity of cell size in the final product. Such additives are
particularly valuable in systems employing a relatively high concentration
of azo compound to initiate polymerization and blow the medium. Such
surfactants may be of the cationic (quarternary salts), anionic
(sulfonates and sulfates) and nonionic (ethylene oxide condensates) type.
Some suitable surfactants include such materials as: metallic soaps,
alkylene oxide-phenol addition products, alkyl aryl sulfates and
sulfonates, dimethyl siloxane polymers, and cationic siloxanes of the
general formula shown in U.S. Pat. No. 3,642,670. Air will also serve as a
nucleating agent. Only a small amount, well dispersed as small bubbles
throughout the resin is needed (as distinguished from the case where one
attempts to foam the resin by beating air into it). It is sufficient to
mix the resin medium with the acid sensitive azo compound hereof (and
other components hereof as desired) in the presence of air. In the
experiments hereof carried out in paper cups and the like, this was
accomplished simply by mixing with an electric stirrer. When one uses
molding equipment involving pumped stream(s) and a mixing head, one simply
bleeds some air to the mixing head.
Hollow ceramic, glass or graphite spheres can be added to the resin medium
in order to decrease further the density of the final formed structure.
These materials have densities less than that of the polymerized matrix
and can be utilized to impart desired density or decorative properties to
the foam.
MOLDING TECHNIQUES
Any means can be used to shape or mold the cellular structure that is
produced during foaming of the resin. The mold system can be quiescent or
dynamic, i.e., the initial reactants may be mixed in a mold in suitable
proportions and permitted to react until the mold is filled or
alternatively, the mixed reactants can be charged into a mold immediately
after mixing, and before substantial gas generation or polymerization. In
other systems the reactants can be mixed and extruded in various forms,
such as sheets, rods, beads, sprays or droplets. Typical molds used in the
furniture industry (room temperature vulcanizable silicone, polyurethane,
and epoxy) are quite acceptable. The resultant foam piece accurately
reproduces surface detail present on the mold. Sheets of the foamed
product may also be formed simply by pouring the mixed reactants upon a
flat surface or calendering the mixed reactants during or prior to
reaction.
CURING THE SHAPED STRUCTURE
A curing agent, for example a non-acid sensitive azo compound or a peroxide
used as a component of the polymerizable medium can substantially increase
the strength of the foamed structure. The exotherm generated during the
gelling step is often sufficient to activate the curing agent. However,
where the curing agent has a half-life that is sufficiently long,
activation of the curing agent may require application of external heat
after blowing and gelling are complete. Curing agents for use in the
polymerizable medium hereof are well known in the art and include (1)
diacyl or diaroyl peroxides or peresters, sometimes in combination with
tertiary amine promoters, or (2) ketone peroxide or peresters sometimes in
combination with cobalt salt activating agents. A typical curing system
employs benzoyl peroxide or t-butyl peroxybenzoate, and a promoter or
activator therefor, such as N,N-dimethylaniline or N,
N-dimethyl-paratoluidine, although in most cases such a promoter or
activator is not necessary.
UTILITY OF THE PRODUCT
Densities of about 25 lb. per cubic foot in the final cellular structure
generally render the structures useful as synthetic wood in applications
such as picture frames or plaques while densities of about 35 lb. per
cubic foot and appropriate for molded components for structural purposes,
such as furniture parts for which wood is normally used. Insulation,
flotation articles, packaging and energy absorption materials, may have
densities of about 2 lb. per cubic foot. Closed cell structures would be
utilized where water resistance is desired while open cell configurations
would be adopted for use as sponges, for example.
SUITABLE AZO COMPOUNDS
As indicated hereinbefore, the identity of the mono and poly azo compounds
useful in this invention are accurately described in FORMULA I. Various
suitable definitions for "Y" in Formula I follow:
When Y is monovalent, it may be halogen, such as Cl or Br; the formula of
"Y" as an ester may be
##STR4##
as an ether is R.sup.1 --X--; as a cyanate and thiocyanate are NCX--; as a
sulfonyl group is
##STR5##
as a urea derivative may be
##STR6##
as hydrocarbyl-oxa(or thia)-amide (or thio-amide) is
##STR7##
as an amine is
##STR8##
and as isocyanate and isothiocyanate are XCN--.
When Y is a divalent radical, examples thereof include those wherein "Y" as
an ester may be
##STR9##
as an ether may be --X--, --X--R.sup.4 --, --X--R.sup.4 --X.sup.1 --; as a
urea derivative may be
##STR10##
as a hydrocarbyl-oxa or thia)-amide (or thio-amide) may be
##STR11##
and as a amine may be
##STR12##
In the foregoing, each of R, R.sup.2 and R.sup.3 in the monovalent and
divalent radicals "(Y)--" is the same or different substituent including
H, a substituted or non-substituted hydrocarbon radical containing 1 to 18
carbon atoms, such as alkyl of 1 to 13 carbons; cycloalkyl of 3 to 12
carbons; aralkyl of 7 to 15 carbons; arcycloalkyl of 9 to 16 carbons; aryl
of 6 to 14 carbons; alkaryl of 7 to 12 carbons; cycloalkaryl of 9 to 12
carbons; alkenyl of 2 to 17 carbons; cycloalkenyl of 5 to 12 carbons; 5
and 6 membered heterocyclic and benzheterocyclic wherein the hetero atoms
are selected from oxygen, sulfur and nitrogen and R and R.sup.2 together
may form an alkylene diradical of 2 to 11 carbons. Any substituent borne
by R, R.sup.2 or R.sup.3 is selected from lower alkoxy, aryloxy, hydroxy,
alkoxycarbonyl, alkanoyloxy and aroyloxy, halogen, alkanoyl, aroyl, cyano,
and carbamoyl. When Y is other than OH, R, R.sup.2 and/or R.sup.3 may also
be substituted by carboxyl; the carbon atom content of the substituents
borne by R, R.sup.2 and R.sup.3 may vary between 1 and 18; R.sup.1 is
substituted or nonsubstituted hydrocarbon radical containing 1 to 18
carbon atoms such as alkyl of 1 to 12 carbons; cycloalkyl of 3 to 12
carbons; aralkyl of 7 to 15 carbons; arcycloalkyl of 9 to 16 carbons; aryl
of 6 to 14 carbons, alkaryl of 7 to 12 carbons; and cycloalkaryl of 9 to
12 carbons; the substituents borne by R.sup.1 is a group containing 1 to
18 carbon atoms selected from t-alkylperoxy-, t-aralkylperoxy,
t-cycloalkylperoxy, t-alkylperoxycarbonyl, t-alkylperoxycarbonyloxy,
alkanoylperoxy, alkanoylperoxycarbonyl,
.alpha.-hydroxyalkylperoxy-.alpha.-hydroxyalkyl,
.alpha.-hydroperoxyalkylperoxy-.alpha.-hydroxyalkyl,
alkanoylperoxycarbonyloxy, di-(t-alkylperoxy)-methylene, alkenyl,
cycloalkenyl, alkynyl, cycloalkynyl, alkoxy, cycloalkoxy, aryloxy,
alkaryloxy, cycloalkaryloxy, aroyloxy, alkaroyloxy, carbamoyloxy,
alkanoyloxy, alkoxycarbonyloxy, cycloalkoxycarbonyloxy,
alkaryloxycarbonyloxy, aryloxycarbonyloxy, alkoxycarbonyl,
cycloalkoxycarbonyl, aryloxycarbonyl, alkaryloxycarbonyl,
alkoxycarbonylamino, cycloalkoxycarbonylamino, aryloxycarbonylamino,
alkaryloxycarbonylamino, alkanoyl, aroyl, alkaroyl, carbamoyl, acylamino,
aroylamino, alkylamino, arylamino, thioalkanoyl, dithioalkanoyl,
thioaroyl, dithioaroyl, alkylthio, arylthio and 5 and 6 membered
heterocyclic and benzheterocyclic wherein the hetero atoms are selected
from oxygen, sulfur, and nitrogen; as well as amino, hydroxy, halogen, and
cyano; R.sup.4 is a substituted and unsubstituted divalent hydrocarbon
radical of 1 to 20 carbon atoms, such as alkylene of 1-20 carbons
(preferably 1-10), cycloalkylene of 3-12 carbons (preferably 5-9), arylene
(normally hydrocarbon arylene) of 6-14 carbons (preferably phenylene),
aralkylene of 7-20 carbons (preferably phenalkylene of 7- 12 carbons), or
cycloalkylalkylene (i.e., a diradical of cycloalkylalkane or
alkylcycloalkylalkyl) of 4-20 carbons (preferably 4-12); such divalent
radicals optionally containing one or two nonterminal and non-adjacent
hetero atoms selected from oxygen, nitrogen, and sulfur in the chain, the
substituents borne by R.sup.4 being any of those defined herein for
R.sup.1 ; R.sup.11 is tertiary alkyl containing 4 to 18 carbon atoms
(preferably 4 to 8) or tertiary aralkyl containing 9 to 18 carbon atoms
(preferably 9 to 12). Each X,X.sup.1, X.sup.2, X.sup.3, X.sup.4 and
X.sup.5 is the same or different oxygen or sulfur.
The identity of the other substituents that satisfy the other valances for
FORMULA I are quite immaterial so long as these azo compounds have the
essential structure recited in FORMULA I. The particular embodiments that
follow hereinbelow only serve to confirm this breadth of the invention.
In particular embodiments, the mono- and poly- azo compounds useful in
accordance with this invention can be illustrated by FORMULA II.
##STR13##
wherein n is 1 or 2;
R.sup.5 is
##STR14##
or one of the substituted or nonsubstituted hydrocarbon radicals defined
herein for R.sup.1, provided that any substituent borne by R.sup.5 is not
linked to the R.sup.5 carbon atom directly attached to an azo nitrogen of
FORMULA II; R.sup.12, R.sup.13, and R.sup.14 are same or different
radicals as defined for R.sup.1 ;
R.sup.6 is
##STR15##
or one of the substituted or nonsubstituted hydrocarbon radicals defined
herein for R.sup.1 ;
R.sup.7 is a substituted or nonsubstituted hydrocarbon radical containing 1
to 18 carbon atoms, such as alkyl of 1 to 12 carbons, cycloalkyl of 3 to
12 carbons, aralkyl of 7 to 15 carbons, and arcycloalkyl of 9 to 16
carbons wherein the substituent borne by R.sup.7 is selected from the
substituents defined herein for R.sup.1 ;
R.sup.7 can be hydrogen when Y is --OH or R--C(=O)O;
R.sup.6 and R.sup.7 may together form a ring (containing 4-12 carbons) with
the carbon linked to the azo nitrogen;
R.sup.7a is the same as R.sup.7 except it is not hydrogen;
R.sup.8 is
##STR16##
R.sup.9 is the same as R.sup.6 except it is not any of the azo radicals
defined therefor;
R.sup.10 is lower alkyl (1 to 6 carbon atoms) or cycloalkyl (5 to 6 carbon
atoms);
Y is defined hereinbefore plus
##STR17##
Y" and R.sup.7 taken together with the carbon linked to the azo nitrogen
form a ring containing 4 to 12 atoms;
Y' is a monovalent group that is the same as Y except Y' is not
##STR18##
Y" is the same as Y when Y is divalent; R.sup.5a is the same as R.sup.5
except that where R.sup.5 is
##STR19##
All other substituents in FORMULA II are defined as in FORMULA I. Examples
of R, R.sup.2 and R.sup.3 radicals; hydrogen, methyl, ethyl, propyl,
butyl, i-butyl, sec-butyl, tert-butyl, octyl, decyl, dodecyl, tridecyl,
cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl,
cyclododecyl, bicyclo [2.2.1] heptyl, adamantyl, perhydronaphthyl, benzyl,
.alpha.-cumyl, p-isopropyl-.alpha.-cumyl, phenylcyclopropyl,
naphthylcyclohexyl, phenyl, naphthyl, phenanthryl, methylphenyl,
triethylphenyl, cyclopropylphenyl, cyclohexylphenyl, ethenyl, allyl,
9-decenyl, 1-propenyl, 8-heptadecenyl, cyclohexenyl, cyclopentenyl,
cyclododecenyl, 2-phenylethenyl, 2-ethoxycarbonylethenyl, p-benzoylphenyl,
2-pyridyl, 4-pyridyl, 2-pyrazinyl, 2-thienyl, 10-xanthenyl,
2-benzimidazolyl, 2-benzothiazolyl, 1-methyl-2-imidazolyl, furyl, and
chloromethyl.
Examples of R.sup.4 diradicals: ethylene, tetramethylene, dodecamethylene,
ethyleneoxycarbonylethyl, trimethyleneoxycarbonylethyl, trimethylene
ethyleneoxyethyl, tetramethyleneaminocarbonylbutyl,
tetramethylenethiobutyl, hexamethylenethiooxycarbonylneopentyl,
p-phenylene, 4,4'-biphenylene, octamethylene-p-phenyl,
p-phenyleneoxycarbonylneopentyl, phenanthrylene, naphthylene,
propenyleneaminocarbonyloxypentyl, cyclohexylene, cyclopentylene,
cyclohexyleneoxycarbonyloxyisoheptyl, chlorophenylene, cyanonaphthylene,
3-phenylpentamethylene, phenylethylenecarbonyloxypropyl, cyclohexenylene,
methylenecarbonyloxypropyl, acenaphthenylene, 2-butenylene, and
pinanylene.
Examples of R.sup.1, R.sup.5, R.sup.6 and R.sup.9 radicals: methyl, ethyl,
propyl, i-propyl, butyl, i-butyl, sec-butyl, tert-butyl, tert-amyl,
t-hexyl, t-octyl, n-dodecyl, cyclopentadecyl, cyclopropyl, cyclobutyl,
cyclopentyl, 1-methylcyclopentyl, cyclohexyl, 1-methylcyclohexyl,
cyclooctyl, cyclododecyl, perhydronaphthyl, adamantyl, bicyclo
[2.2.1]heptyl, 9,10-ethano-9,10-dihydro-9-anthracyl, benzyl,
.alpha.-cumyl, p-phenyl-.alpha.-cumyl 2-phenylcyclopropyl,
4-naphthylcyclohexyl, naphthylneopentyl, phenyl, naphthyl, phenanthryl,
toluyl, xylyl, 4-ethyl-1-naphthyl, m-cyclopropylphenyl,
p-cyclohexylphenyl, and triethylphenyl.
Additional R.sup.5 radicals include propionyl, naphthoyl,
isopropoxycarbonyl, triethylsilyl, tripropylgermanyl, carbamoyl,
N-methylcarbamoyl, diethylamino, penten-2-yl, cyclopenten-1-yl,
diethylphosphono, dibutylphosphinyl, bis-(diethylamino-phosphinyl,
dibutylphosphinothioyl.
Examples of R.sup.7 radicals: same as for R.sup.5 radicals except the
aromatic radicals and "Additional R.sup.5 radicals" are excluded, i.e.,
"phenyl, naphthyl, . . . and triethylphenyl", and "propionyl, . . .
dibutylphosphinothioyl." inclusive.
Examples of R.sup.10 radicals: methyl, ethyl, propyl, i-propyl, butyl,
i-butyl, sec-butyl, tert-butyl, pentyl, hexyl, cyclopenetyl, and
cyclohexyl.
Examples of R.sup.11 radicals: t-butyl, t-amyl, t-octyl, .alpha.-cumyl,
p-isopropylcumyl, 1,1-dimethyl-hexadecyl, p-(.alpha.-cumyl)cumyl.
Examples of Substituents borne by R.sup.1, R.sup.4 through R.sup.7
inclusive, R.sup.9 and R.sup.11 : ethenyl, allyl, hexenyl, cyclopentenyl,
methylcyclohexenyl, ethynyl, propynyl, hexynyl, cyclooctynyl, methoxy,
ethoxy, propoxy, hexoxy, isopentoxy, methylcyclopentoxy, cyclohexoxy,
phenoxy, naphthoxy, chlorophenoxy, dimethylphenoxy, ethylphenoxy,
cyclohexylphenoxy, acetoxy, propionoxy, isohexanoyloxy,
cyclohexanecarbonyloxy, benzoyloxy, naphthoyloxy, chlorobenzoyloxy,
methylbenzoyloxy, methylnaphthoyloxy, carbamoyloxy, dimethylcarbamoyloxy,
phenylcarbamoyloxy, methoxycarbonyloxy, propoxycarbonyloxy,
cyclohexoxycarbonyloxy, methylphenoxycarbonyloxy, phenoxycarbonyloxy,
chlorophenoxycarbonyloxy, naphthoxy- carbonyloxy, methoxycarbonyl,
ethoxycarbonyl, butoxycarbonyl, cyclohexoxycarbonyl, phenoxycarbonyl,
naphthoxycarbonyl, chlorophenoxycarbonyl, methylphenoxycarbonyl,
methylbiphenyloxycarbonyl, methoxycarbonylamino, ethoxycarbonylamino,
isopropoxycarbonylamino, cyclohexoxycarbonylamino, phenoxycarbonylamino,
naphthoxycarbonylamino, chlorophenoxycarbonylamino,
methylphenoxycarbonylamino, methylnaphthoxycarbonylamino, acetyl,
propionyl, valeroyl, cyclohexanecarbonyl, benzoyl, naphthoyl,
tertiarybutylperoxy, tertiarybutylperoxycarbonyl,
tertiarybutylperoxycarbonyloxy, benzoylperoxy, decanoylperoxycarbonyl,
chlorobenzoyl, methylbenzoyl, methylnaphthoyl, carbamoyl,
diethylcarbamoyl, methylcarbamoyl, phenylcarbamoyl, carboxy, chlorine,
bromine, iodine, fluorine, hydroxy, cyanide, 2-furyl, amino, thiophenoxy,
indolinyl, pyridyl, pyrazinyl, thienyl, furyl, xanthenyl, benzimidazolyl,
benzothiazolyl, 1-methylimidazolyl, acetamino, benzoylamino, butylamino,
phenylamino, diethylamino, cyclohexanecarbonylamino, thiobutyryl,
dithiodecanoyl, thiobenzoyl and dithionaphthoyl.
Examples of Substituents borne by R, R.sup.2 and R.sup.3 : methoxy, ethoxy,
propoxy, isopropoxy, butoxy, sec-butoxy, t-butoxy, phenoxy,
parachloropheoxy, ortho- meta- and paramethylphenoxy, hydroxy,
methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl,
butoxycarbonyl, t-butoxycarbonyl, acetyloxy, propionyloxy, butyryloxy,
valeroyloxy, hexanoyloxy, benzoyloxy, parachlorobenzoyloxy,
2,4-dichlorobenzoyloxy, naphthoyloxy, chloro, bromo, iodo, fluoro, acetyl,
propionyl, butyryl, valeroyl, hexanoyl, 2-ethylhexanoyl, benzoyl,
naphthoyl, cyano, N-methylamido, N,N-dimethylamido and N,N-diethylamido.
Examples of R.sup.6 and R.sup.7 linked together: trimethylene,
pentamethylene, heptamethylene, decamethylene, tetramethylene,
1,1,3,3-tetramethylpropylene, undecamethylene, and 1,2, or
3-methylpentamethylene.
Examples of R and R.sup.2 linked together: same as for Examples R.sup.6 and
R.sup.7 linked together, plus ethylene. polycarboxylic -, -diol, -diol,
Examples of Y radicals: chlorine, bromine, acetoxy, propionoxy, formyloxy,
methacryloxy, butyryloxy, undecelynoyloxy, lauroyloxy, decanoyloxy,
cyclopropylcarbonyloxy, cyclohexanecarbonyloxy, cyclododecanecarbonyloxy,
cyclohexenecarbonyloxy, propargyloxy, phenylacetoxy, phenoxyacetoxy,
pivaloyloxy, 2-ethylhexanoyloxy, pelargonoyloxy,
3-ethoxycarbonylpropionoxy, 4-ethoxycarbonylbutyryloxy,
5-methoxycarbonylvaleryloxy, 9-ethoxycarbonylpelargonoyloxy,
hydroxypivaloyloxy, cyanoacetoxy, 3-methoxypropionoxy,
6-acetoxyhexanoyloxy, 6-benzyloxycarbonylaminohexanoyloxy, benzoyloxy,
naphthoyloxy, phenanthrenecarbonyloxy, toluoyloxy, methoxy, ethoxy,
isopropoxy, dodecyloxy, cyclohexyloxy, cyclopropyloxy, cyclododecyloxy,
benzyloxy, .alpha.-cumyloxy, phenoxy, naphthyloxy, phenanthryloxy,
m-methylphenoxy, p-methylphenoxy, methylamino, butylamino, dodecylamino,
N-methylanilino, phenylamino, diethylamino, methylaminothiocarbonylamino,
butylaminothiocarbonylamino, dodecylaminothiocarbonylamino,
butylaminocarbonylamino, ethoxycarbonylamino, isocyanato, isothiocyanato,
cyanato, thiocyanato, ethoxythiocarbonylamino, perchloroacryloxy,
perfluoro-9-methyldecanoyloxy, 4-acetylbutyryloxy, adamantylacetoxy,
3-aminobutyryloxy, p-aminothiophenoxyacetoxy, m-bromocinnamoyloxy,
cyanoacetoxy, 4-chlorobutyryloxy, propionyloxy, cyclohexylacetoxy,
3,4-dimetoxycinnamoyloxy, diphenylacetoxy, 3-ethoxycarbonylacryloxy,
4-hydroxybutyryloxy, 3-indolinylacryloxy, iodacetoxy, tridecanoyloxy,
2-naphthylacetoxy, 3-phenoxypropionoxy, 2-pyridylacetoxy, pyruvoyloxy,
9-anthracenecarbonyloxy, 4-benzoylbenzoyloxy, 2-hydroxy-benzoyloxy,
1-methylcyclohexanecarbonyloxy, isonicotinoyloxy, 2-pyrazinecarbonyloxy,
2-thiophenecarbonyloxy, 10-xanthenecarbonyloxy, 3-acetamidophenoxy,
2-allylphenoxy, 1-amino-2-naphthoxy, 4-cyanophenoxy,
4-acetamidothiophenoxy, allylthio, butoxycarbonylmethylthio,
cyclohexylthio, 2-furylmethylthio, 2-thiobenzimidazole,
2-thiobenzothiazole, 2-thio-1-methylimidazole, 2-pyridylthio,
isopropylthio, t-butylthio, octylthio, dodecylthio, 2-hydroxyethylthio,
thiophenoxy, p-t-butylphenylthio, hydroxy, thioacetoxy, dithioacetoxy, and
thiobenzoyloxy, sulfur, oxygen, ethylenedioxy, trimethylenedioxy,
hexamethylenedithioxy, hexamethylenediamino, decanedithiol,
phenylenedioxy, naphthylenedioxy, phenanthrylenedithioxy,
oxyhexamethylenethioxy, oxyphenylenethioxy, aminophenyleneoxy, and
aminohexamethylenethioxy.
METHODS OF PREPARATION OF THE AZO FOAMING AGENTS
A. Symmetrical Azos
##STR20##
1. The .alpha.,.alpha.'-dihalo-azohydrocarbon compound (Y=Cl or BR) can be
prepared by condensation of the ketone with hydrazine and the addition of
halogen to the resulting ketazine - Goldschmidt and Acksteiner, Ann. 618,
173 (1958); Chem. Ber. 91, 502 (1958) the disclosure of which is
incorporated herein by reference.
2. Azo compound having ester groups attached to both alpha carbons [Y is--
X.sup.1 C(=X)R] can be prepared by one of several methods.
(a) Those derived from low molecular weight aliphatic acids can be prepared
(Example 2 hereof) by reacting .alpha.,.alpha.'-dihalo-azo-hydrocarbon
compounds with metal salts of the appropriate acids in the presence of
that acid according to the method described by Benzing U.S. Pat. No.
3,282,912, the disclosure of which is incorporated herein by reference.
(b) Those prepared from higher molecular weight acids and aromatic acids
can be prepared by reacting the .alpha.,.alpha.'-dihalo-azohydrocarbon
compounds with salts of the acids in an inert solvent.
(c) Those derived from aliphatic liquid acids can be prepared by
halogenating the ketazine in the acid in the presence of a salt of that
acid. This method is also described by Benzing in U.S. Pat. No. 3,282,912.
(3) Symmetrical azo compounds having ether groups (Y is-- XR) attached to
both alpha carbon atoms can be prepared by reacting
.alpha.,.alpha.'-dihalo-azohydrocarbon compounds with a metal salt (MY).
This reaction is fundamentally the same as that used to prepare the azo
compounds having ester groups attached to both alpha carbon atoms. For
example, .alpha.,.alpha.'-diphenoxyazoalkanes were prepared by reacting
the appropriate .alpha.,.alpha.'-dichloroazo-alkanes with sodium phenoxide
in methanol. In another embodiment of this same reaction, the
.alpha.,.alpha.'-dialklthio and .alpha.,.alpha.'-diarylthioazoalkanes were
prepared by forming the sodium or potassium salts of the mercaptans in
methanol and then adding a pentane solution of the
.alpha.,.alpha.'-dichloroazoalkane to the methanol solution of the
mercaptan salt at room temperature. The reaction mixture was stirred 1/2
hour to 1 hour, poured into water and the product extracted with methylene
chloride, washed with 5% NaOH, 10% NaHCO.sub.3 solution, dried and the
methylene chloride evaporated under reduced pressure.
4. Symmetrical azo compounds having cyanate and thiocyanate groups (Y is
NCX--) and isocyanate and isothiocyanate groups (Y is XCN--) attached to
the alpha carbon atoms can be prepared by this same procedure. For
example, the .alpha.,.alpha.'-dithiocyanato and .alpha.,
.alpha.'-diisothiocyanatoazoalkanes were prepared by reacting the
.alpha.,.alpha.'-dichlorozoalkanes with sodium thiocyanate in 75% aqueous
isopropanol; the reaction mixture was diluted with water, extracted with
methylene chloride and the methylene chloride evaporated under reduced
pressure; the residue, a mixture of liquid and solids, was recrystallized
from pentane. The .alpha.,.alpha.'-dithiocyanatoazoalkanes are solids and
are relatively insoluble in pentane (IR-sharp weak band at 2400
cm.sup.-.sup.1). The .alpha.,.alpha.'-diisothiocyanatoazoalkanes are
liquids and relatively soluble in pentane (IR-strong broad band at
2000-2200 cm.sup.-.sup.1). The percentage of the two isomers varies with
the starting .alpha.,.alpha.'-dichloroazoalkane and the reaction
conditions. In yet another embodiment of this same method, the
.alpha.,.alpha.'-diisocyanatoazoalkanes were prepared by reacting the
.alpha.,.alpha.'-dichloroazoalkanes with potassium cyanate in 70% aqueous
isopropanol or aqueous acetone. The reaction mixture was diluted with
water and extracted with pentane. The pentane solution was dried and the
pentane evaporated under reduced pressure.
5. The .alpha.,.alpha.'-diisothiocyanatoazohydrocarbon compounds and the
.alpha.,.alpha.'-diisocyanatoazohydrocarbon compounds can be reacted with
active hydrogen compounds. For example,
.alpha.,.alpha.'-diisothiocyanatoazoalkanes and
.alpha.,.alpha.'-diisocyanatoazoalkanes were reacted with ammonia, primary
and secondary amines to convert them to thioureas and ureas respectively.
In another embodiment of this method
.alpha.,.alpha.'-diisothiocyanatoazoalkanes and
.alpha.,.alpha.'-diisocyanatoazoalkanes were reacted with hydrazines to
convert them to thiosemicarbazide and semicarbazide derivatives
respectively. Similarly, reaction of .alpha.,.alpha.'-diisothiocyanato-
and diisocyanatoazohydrocarbon compounds with alcohols, phenols or thiol
will convert them to thiocarbamates and carbamates.
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