Note: Descriptions are shown in the official language in which they were submitted.
1049700
This invention relates to compositions for the preparation
of cellular vinyl chloride polymers. The compositions contain certain
organotin compounds which not only effectively activate the blowing
agents employed in preparing cellular vinyl chloride polymers but also
impart superior levels of heat stability to the final product.
Cellular vinyl chloride polymers are conventionally prepared
by melting a vinyl chloride resin in the presence of a blowing agent
which decomposes at the processing temperature to yield a gas. The
bubbles of gas evolved are entrapped within the molten resin, thereby
forming a cellular structure. The foaming operation is usually performed
while the resin is contained in a heated mold or in the heated barrel
of an extruder, so that the resin can be simultaneously foamed and
shaped into commercially useful articles, including pipe, decorative
molding and structural siding. One class of blowing agents often em-
ployed in preparing cellular vinyl chloride polymers is the azodicarbon-
amides, exemplified by azobisformamide
O O
ll ll
(NH2C-N=N-C-NH2). The blowing agent is preferably employed in combina-
tion with an activator for the purpose of increasing both the degree and
rate of blowing agent decomposition. The resultant larger volume of gas
generated is desirable, since it increases the efficiency of the blowing
agent, thereby reducing the amount of blowing
B
,. . . . .... -. ~ . . . .. . . ~.
..
1049700
agent required. Temperatures employed to melt the polymer
and decompose the blowing agent are bet~een 150 and 200C.
It therefore becomes necessary to include in the formulation
a stabilizer for the purpose of eliminating or at least
minimizing the heat-induced discoLoration of the vinyl
chloride polymer which would otherwise occur at these
temperatures. To increase efficien~cy and reduce costs it
would be desirable to e~ploy a single compound which
functions effectively as both an activator for the blowing
agent and a heat stabilizer.
It is well known that a variety of organotin
compounds, particularly dibutyltin derivatives of
mercaptocarboxylic acid esters will impart useful levels
of heat stability to vinyl chloride polymers. German
Patents 2,133,372 and 2,047,969 disclose the use of
organotin mercaptocarboxylic acid esters in foamed
polyvinyL chloride. These compounds stabilize welL but
do not effectively activate blowing agents such as
azobisformamide. Organotin carboxylates such as dibutyltin
maleate, dibutyltin dilaurate and dibutyltin maleate-half-
esters are disclosed in Japanese Patent 6264/67 as being
useful in flexible, i~e., plasticized, polymer foams~
Although these organotin compounds activate azodicarbonamides,
they are poor thermal stabilizers for the polymer. Thus,
it can be seen that organotin mercaptocarboxylic acid esters
, ~ .. .. .. : .. ~ . . . . .
ll 1049700
impart good thermal stability but poor blowing agent
activation, while organotin carboxylates offer good
activation, but poor thermal stability with a resultant
lack of proper meLt viscosity control.
In addition to dimethyltin-, dibutyltin_ and
dioctyltin-mercaptocarboxylic acid esters, other compounds
that are effective heat stabilizers for vinyl chloride
polymers but poor blowing agent activators are
bis(dialkyltin-monomercaptocarboxylic acid ester) sulfides
such as bis(dibutyltin-isooctylmercaptoacetate) sulfide,
bis(monoaLkyltin-dimercaptocarboxylic acid ester) sulfides
such as bis(monobutyltin-di-isooctylmercaptoacetate) sulfide,
(monoalkyltin-dimercaptocarboxylic acid ester) (dialkyltin-
mercaptocarboxylic acid ester) sulfides, e.g., (m~nobutyltin-
di-isooctylmercaptoacetate) (dibutyltin-isooctylmercaptoacetate )
sulfide, and monoalkyltin tris-mercaptocarboxylic acid
esters, e.g., monobutyltin tri~(isooctylmercaptoacetate).
Other organotin compounds have been found to be
relatively ineffective with regard to both thermal stability
and ability to activate blowing agents. m ese compounds
include monoalkylthiostannoic acids and their anhydrideæ,
e.g " butylthiostannoic anhydride, dialkyltin sulfides,
e.g., dibutyltin sulfide, trialkyltin mercaptocarboxylic
acid esters, e.g., tributyltin-isooctylmercaptoacetate,
and tin-tetramercaptocarboxylic acid esters, such as
tin-te~ra(isooctylmercaptoacetate).
_ . . - ~ -
1049700
Organotin carboxylates which are good blowing
agent activators but poor thermaL stabiLizers, are
monoaLkyltin tris(dicarboxylic acid half-esters) such as
monobutyltin tris(dodecyL maleate), dialkyltin dicarboxyLic
acid compounds such as dibutyltin azelate, and dialkyltin
monocarboxylic acid derivatives, e.g., dibutyltin bis(tall
oil atty acid carboxylate) and dibutyltin bis(benzoate).
While it may appear obvious to attain the desired
effect by combining one of the foregoing good heat stabilizers
with an efective activator for the blowing agent, this
approach only slightly improves the overall perormance.
The mixtures provide adequate thermal stabilization but
only a marginal improvement in degree of blowing agent
l activation.
¦ A number of non-tin-containing stabilizer-activators
are currently available for use in rigid cellular polyvinyl
chloride formulations~ These products are almost exclusively
based on compounds of barium, cadmium and lead. A major
deficiency of many of these compounds is their relatively
high toxicity. In addition, these metaL-based compounds
have been found to be less effective in static and dynamic
thermal stabiLization o PVC than many organotin compounds.
More importantly, they cause decomposition of the
azodicarbonamide blowing agent at so low a temperature that
the gas is generated before it can be efficiently utilized,
. . . . , ~ .
1049700
in other words before the polymer is in a completely
molten state and therefore capable of entrapping the gas
to form the desired cellular structure.
An objective of this invention is to provide
foamable vinyl chLoride poLymer compositions that exhibit
good thermal stabiLity and blowing agent activity.
Unexpectedly it has now been found that certain
organotin sulfur-containing compounds provide an optimum
balance between good blowing agent activation and good
thermal stability. AdditionalLy, it has been found that
these compounds can be combined with selected oxygencontaining
organotin compounds or metal salts of carboxylic acids to
provide the desired combination of excellent blowing agent
activation and good thermal stability.
1049700
The present invention provides a composition for preparing
cellular vinyl chloride polymers, said composition comprising:
a) lO0 parts by weight of a vinyl chloride homopolymer or a copoly-
mer of vinyl chloride with a copolymerizable ethylenically unsaturated
monomer,
b) between 0.1 and lO parts of a blowing agent, and
c) between 0.1 and 10 parts of a combined blowing agent activator
and heat stabilizer which in turn comprises
i) between 5 and 100% by weight of a diorganotin compound
of the formula R2Sn~SR2)2 and
ii) between 0 and 95% by weight of an auxiliary activator-
stabilizer selected from the group consisting of organotin compounds of
the general formula RaSnX4 a and metal salts of carboxylic acids contain-
ing between 4 and 18 carbon atoms wherein the metal is selected from
Group II B of the Periodic Table, wherein Rl represents an alkyl radical
containing between 1 and 18 carbon atoms, inclusive, or a cycloalkyl, aryl,
alkaryl or aralkyl radical, each of which contains between 6 and 18 carbon
atoms, inclusive, and R2 represents an alkyl radical containing between
4 and 18 carbon atoms, inclusive, or an aryl, alkaryl or aralkyl radical,
each of which contains between 6 and 18 carbon atoms, inclusive, R3 is
selected from the same group as Rl, X represents a radical selected from
the group consisting of
O O O O O O X O
,. " " " " " ,3-a "
-o-C-R4-C-oH, -o-C-CH=CH-C-oR5, -O-C-R4-C-OSnRl, -OCR6, R and R where-
in R represents an alkylene, arylene or aralkylene radical containing be-
tween 1 and 12 carbon atoms, inclusive, R5 and R6 are selected from the same
group as Rl, R7 represents the residue resulting from removal of the hydro-
gen atoms from a hydroxyl group of a phenol or an alcohol, said alcohol
containing between 2 and 18 carbon atoms and 1 to 4 hydroxyl radicals, R8
represents a radical of the formula RaSn-O- and a represents the integer
3-a
1 or 2~
~ 6 --
B
~ - . . ,
1049700
The diorganotin dimercaptide or the combination of said
dimercaptide with the compound RaSnX4 a and metal carboxylate is employed
at a total concentration of 0.1 to 10 parts per 100 parts of resin.
The unique combination of blowing agent activation and heat
stabilization of cellular vinyl chloride polymers is achieved using di-
organotin dimercaptides of the general formula R12Sn~SR2)2 wherein Rl
represents an alkyl radical containing between 1 and 18 carbon atoms,
inclusive, or a cycloalkyl, aryl, alkaryl or aralkyl radical, each of
which contain between 6 and 18 carbon atoms, inclusive and R2 represents
an alkyl radical containing between 4 and 18 carbon atoms or a cycloalkyl, i~
aryl, alkaryl or aralkyl radical, each of which contain between 6 and 18
carbon atoms, inclusive. Alkyl radicals which can be represented by Rl
include methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl,
n-hexyl, n-octyl, iso-octyl and 2-ethylhexyl in addition to the isomeric
decyl, dodecyl, heptadecyl and octadecyl radicals. When R2 represents
an alkyl radical it can be selected from the same group as Rl with the
proviso that it contain at least 4 carbon atoms.
n
~ .
1049700
When ~ and/or R represent cycloal.kyL radicals,
these include cyclopentyl, cyclohexyl, cycloheptyL and
. cyclooctyl, each of which may contain one or more alkyl
radicals as substituents, for example 2-methyl cycLohexyl.
Aryl radicals which can be represented by R
and/or R include phenyl, naphthyl, biphenyl and anthracenyl.
When R , R or both represent alkaryl radicals
they can be tolyl, o-, p- or m-xylyl, or ethyl phenyl,
among others. Suitable aralkyl radicaLs include benzyl,
~-phenylethyl and ~'-phenylpropyl, among others.
Preferred diorganotin mercaptides include the
following:
dimethyltin-S,S'-bis(bwtyl mercaptide)
dimethyltin-S,S'-bis(lauryl mercaptide)
dimethyltin-S,S'-bis(2-ethylhexyl mercaptide)
dimethyltin-S,S'-bis~stearyl mercaptide)
dimethyltin-S,S'-bis(benzyl mercaptide)
dimethyltin-S,S'-bis(tridecyl mercaptide) `
in addition to the corresponding dipropyltin, dibutyltin,
dicyclohexyltin, di-n-octyltin, distearyltin and diphenyltin
derivatives of these mercaptans, .
me efficacy of the diorganotin dimercaptides
both as activators for the blowing agent and as heat
stabilizers is substantially increased when the dimercaptide
is used in combination with a mono- or diorganotin derivative
of a carboxylic acid, alcohol or phenol. These derivatives
exhibit the general formula RaSnX~_a wherein R , X and a
are as previously defined. The carboxylic acids can be
either aliphatic or aromatic and contain between 1 and 18
carbon atoms. Aliphatic acids may be saturated or may
.. . .
. , - . . . - . : ~
. ~, . ,- . . . . .
1049700
exhibit one or more do~ble bond.s between adjacent carbon
atoms such as ~re present in malei.c and oleic acids and
the fatty acids derived from tall oil. The acids can be . .
poLyfunctional, such as maleic acid and phthalic acid.
Suitable carbo~ylic acids contain between 2 and 18
carbon atoms and include acetic, propionlc, maleic, butyric,
hexoic, butanedioic, lauric, stearic, octadecanoic, oleic,
benzoic and the isomeric phthalic acids. The alcohols
which can be employed to prepare the organotin compound
include monofunctional alcohols such as methanol, ethanol,
isomeric butanols, hexanols, dodecanols, octadecanols and
cyclohexanol. Polyfunctional alcohols such as the alkylene
glycols, glycerine and pentaerythritol are also suitable.
Organotin derivatives of phenols and alkylated phenols
can also be employed in combination with the present
diorganotin dimercaptides.
Blowing agent activation and heat stability are
further enhanced if the aforementioned organotin compounds
are employed in combination with 1-10%, based on the weight
of the stabi:Lizer-activator composition, of soaps of
Group IIB metals, wherein the carbo~ylic acid residues each
contain between 4 and 18 carbon atoms.
When in accordance with a preferred embodiment
of this invention, the diorganotin mercaptides are employed
in combination with a mono- or diorganotin compound containing
at least one tin-oxygen bond, the combination may be present :
.,
.... . - , - . . ~ ,
~ . . .. . .
1049700
as a physical mixture or at least partly in the form of
one or more reaction products. The chemical and patent
. literature containsnumerous examples demonstrating that
members of two or more different classes of organotin
compounds may react with one another under certain conditions
to yield products containing one or more tin atoms wherein
at least a portion of the tin atoms are bonded to different
combinations of radicals than were present in the starting
materiaLs. While the mechanism for the reactions involved
may not be completely understood, the end result is that
the hydrocarbon, mercaptide, carboxy
O .
(R-C-O), alkoxy and/or araloxy radicals present in the
organotin compounds of this invention may be transferred
from one tin atom to another. For example, a mixture
of dibutyltin dilauryl mercaptide and monooctyltin trilaurate
could conceivably react to yield a compound wherein the tin
atom i8 bonded to one butyl, one octyl, one laurylmercaptide
(ClzH2~S-) and one laurate radical.
Vinyl chloride polymer compositions which yield
cellular materials when heated are conveniently prepared
by blending the polymer together with the blowing agent,
organotin compound(s) and other ingredients to obtain a
homogeneous mixture. The organotin compounds present,
which consist of the aforementioned diorganotin dimercaptides
either alone or preferably in combination with a mono- or
diorganotin derivative of a carboxylic acid, alcohol or
-10-
1049700
phenol as described hereinbefore, constitute between 0.1 and
10%, based on the weight of the polymer composition. If
organotin compounds other than the aforementioned dimercaptides
are present, these compounds constitute between 5 and 95%,
based on the total weight of the organotin compounds,
preferably between 5 to 50%.
It has been disclosed hereinbefore that the
performance exhibited by the organotin compounds of this
invention can be further enhanced by the presence of between
1 and 10%, based on the weight of the ~tabilizer-activator
composition, of salts derived from carboxylic acids and
elements from Group IIB of the periodic table. m ese
elements include zinc, cadmium and mercury, with salts of
zinc being preferred, such aæ zinc stearate.
The pre8ent compositions can utilize any of the
known blowing agents that are conventionally employed for
preparing celLular vinyl chLoride polymers. The
concentration of blowing agent is usually between 0.2 and
5~0qO~ based on the weight of the polymer composition prior
to ~oam formation.
In addition to the bLowing agent activator-heat
stabilizer compositions described in the foregoing
specification and appended claims, the vinyl chloride
polymer compositions of this invention may contain additives
for the purpose of increasing the heat 8tability,resistance
1049700
to oxidation, flame retardancy and impact resi~tance of
the polymer. ConventionaL processing acids such as lubricants
and plasticizers can also be present.
Useful heat stabilizers include diorganotin
S derivatives of mercaptoacid esters, particularly those
wherein the hydrocarbon radicals bonded to the tin atom
contain between 1 and 8 carbon atoms; trialkyl or triaryl
e6ter~ of phosphorus acid, in¢luding symmetrically and
unsymmetrically substituted triorgano phosphite such as
tris(nonyl phenyl phosphite); esters of thiodipropionic
acid; compotmds containing one or more epoxide group6
(` C\- C ~) such as are disclosed in UDS. Patent 2,997,454
and a- or ~- mercapto acids such as thiolactic acid and
~-mercaptopropionic acid~
Among the antioxidant~ suitable for use in the
present polymer compositions are phenols, particularly tho~e
wherein the positions adjacent to the carbon atom bearing
the hydroxyl radical contain alkyl radicals as substituents.
Phenols wherein this alkyl radical is sterically bulky, e.g.
a tertiary butyl radical, are preferred.
When plasticizers are to be employed, they may
be incorporated into the polyvinyl chloride resins in accord-
ance with conventional means. The conventional plasticizer~
can be used, such as dioctyl phthalate, dioctyl sebacate and
tricresyl phosphate. Where a plasticizer is empLoyed, it can
be used in an amount within the range from 0 to 100 parts by
weight of the resin.
-12-
,' '...
. . :, . . i ~ . .:
1049700
Particularly useful pla~ticizers are the epoxy
higher esters having from about twenty to about one hundred
fifty carbon atoms. Such esters will initially have had
unsaturation in the alcohol or acid portion o$ the molecule,
which i8 taken up by the formation of the epoxy group.
Typical unsaturated acids are oleic, Linoleic,
linolenic, erucic, ricinoleic and brassidic acids, and these
may be esterified with organic monohydric or polyhydric
alcohols, the total number of carbon atoms of the acid and
the alcohol being within the range stated. Typical mono-
hydric aLcohol6 include butyl alcohol, 2-ethylhexyl alcohol,
lauryl alcohol, isooctyl alcohol, stearyl alcohol, and oleyl
alcohol. The octyl alcohols are preferred. Typical
polyhydric alcohols include pentaerythritol, glycerol,
ethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol,
neopentyl glycol, ricinoleyl alcohol, erythritol, mannitol
and ~orbitol. Glycerol is preferred. mese alcohols may
be fully or partially esterified with the epoxidized acid.
Also useful are the epoxidized mixtures of higher fatty acid
esters found in naturally-occurring oils such as epoxidized
soybean oil, epoxidized olive oiL, epoxidized cotton~eed oil,
epoxidized tall oil fatty acid esters, epoxidized linseed
oil and epoxidized tallow. Of these, epoxidized soybean oil
iB preferred.
me alcohol can contain the epoxy group and have a
long or short chain, and the acid can have a short or long
chain, such as epoxy stearyl acetate, epoxy stearyl stearate,
glycidyl stearate, and polymerized glycidyl methacrylate.
'. ~ . .
- ~ :
1~ 1049700
A small amount, usually not more than 1.5%, of a
parting agent or Lubricant, aLso can be included. TypicaL
parting agents are the higher aliphatic acids, and ~alts
having twelve to twenty-four carbon atoms, such as ~tearic
acid, lauric acid, palmitic acid and myristic acid, lithium
stearate and calcium palmitate, mineral lubricating oilæ,
polyvinyl stearate, polyethylene and paraffin wax.
Impact modifiers, for improving the toughness or
impact-resistance of unplasticized resins, can also be added
to the resin compositions stabilized by the present invention
in minor amounts of usually not more than lO~o . Examples of
such impact modifiers include chlorinated polyethylene, ABS
polymers, and polyacryLate-butadiene graft copolymers.
As used in this specification, the term "vinyl
chloride pblymers" refers both to vinyl chloride homopolymers
and to copolymers wherein at least 50~ of the repeating
units are derived from vinyl chloride, the remainder being
derived from one or more ethylenically unsaturated compounds
that will copolymerize with vinyl chloride. Suitable
comonomers include but are not limited to vinyl acetate,
vinylidene chloride, ethylene and other olefinic hydrocarbons,
acrylonitrile, and esters of acrylic or methacrylic acids.
. . ,
1049700
The following examples demonstrate preferred
embodiments of this invention and should not be interpreted
as limiting the scope thereof. ALl parts are by weight
unless otherwise specified.
S EX~LE 1
This exampLe demonstrates the extent to which
O O
azobisformamide (N~I2C-N=N-CNH2), a conventional bLowing
agent for preparing cellular vinyl chloride polymers, is
activated usinglvarious compounds. me degree of activation
was determined by measuring the volume of gas evolved while
a mixture containing 100.0 g. of dioctyl phthalate, 1.0 g.
of azobisformamide and 2.0 g. o the indicated activator was
being heated from ambient temperature to 220C. at a rate of
5C. per minute. The purpose of the dioctyl phthalate was to
provide the suspending medium for a homogeneous system.
The mixture was placed in a 250 c.c.-capacity
l-neck-round bottomed flask equipped with a thermometer and
an outlet tube. The gas evolved which consisted of nitrogen
and oxides of carbon was colLected by displacement of water
from a graduated cylinder. The volume of gas which had been
collected when the temperature of the mixture reached a
specified level was recorded. These data appear in Table I.
The theoreticaL yield of gaseous products from one gram of
azobisformamide i8 about 230 c.c., measured at standard
temperature (25C.) and pressure (760 m.m. Hg).
-15-
1049700
Tl~BLE I
ACTIVATOR TOTAL VOLI~E OF GAS COLLECTED( IN c . c . )
- - WHEN THE IEMPERATURE: RE~CIED
130C.150C. 170C.L90C. 210C. 220C
- . . _ _ _ _
None 3 10 lO 15 80 205
Di-n-butyltin- l
S,S'-bis(IOMA) (A)0 5 15 75 165 185
Barium-C~dmium 3 3
Mixture (B) 20 llO 195 - 235
10Di-n-butyltin-S,S'-
bis(dodecyl 3 3
mercaptide~ (C) 0 10 40 220 -- --
.
1 IOMA = isooctyl mercaptoacetate.
2 A mixture of barium and cadmium carboxylates containing
7% by weight of barium and 14% cadmium.
3 Gas evolution was substantially complete.
Of the three formulations tested, only the one
containing di-n~but~Ltin-S,S'-bis(dodecyL mercaptide) provided
the major portion of gas evolution between temperatures of
170 and 190C. Since polyvinyL chloride is conventionally
processed at temperatures between 170 and 200C., only gas
evoLved at these temperatures wouLd be effectively utiLized
in foam formation. `
The ~ormulations which contained either no activator
or the isooctyl mercaptoacetate derivative did not exhibit
significant gas evolution until the temper~ture exceeded 200C.
These higher temperatures could accelerate degradation of the viny]
chloride polymer resu~ting in a darkening and embrittlement to
the extent that the polymer is no longer considered a commercially
useful product.
. . . . ~ . . -
1049700
The ~ormulation containing the mixture of barium
and cadmium carboxylates is considered ineî~icient for
the preparation of cellular vinyl chloride polymers because
most of the gas had been evolved when the temperature reached
170C., and therefore could not be completely utilized in
foam formation since the polymer would be a solid or a
viscous semi-solid below this temperature .
EXAMPIE 2
This example demonstrates that a number of organotin
LO derivatives of isooctyl mercaptoacetate are not suitable as
blowing agent activators for preparing cellular vinyl chloride
polymers.
The test formulation was identical to that described
in Example 1 and contained the organotin compounds listed
in the following table as prospective activators for the
azobisformamide.
TABLE II
ACTIVATOR TOTAL VOLUME OF GAS (C.C.) COLLECTED WHEN
THE TEMPERATURE REACHED
170C. 180C.190C. 200C. 210C. 220 C.
Dimethyltin S,S'-
bis-IOMA' 10 18 80 160 180 190
Dioctylti~ S,S'-
bis-IOMA 18 30 100 165 185 195
Tin Tetra IOMA 3 10 33 65 79 92
Monobutyltin-
S,S'-S" tris-
IOMA 10 50 95 118 135 150
Tributyltin-S-IOMA10 19 38 72 135 165
None 10 10 15 23 75 195
~ . . .
1 isooctyl mercaptoacetateO
.
.
1049700
None of the formulations set forth in TabLe II
generated substantial amounts of gas at temperatures below
L90C. The class o organotin mercapto acetic acid esters
appears to be relatively ineffective as an activator for the
blowing agent at temperatures conventionaLLy employed to
process cellular vinyl chloride polymers,
Since diorganotin derivatives of mercaptoacetic
acid esters are among the best single component stabilizers -
for vinyl chloride polymers, it would therefore appear
reasonable to employ these compounds in combination with
other organotin compounds which would be expected to function
as activators for the blowing agent. To test the validity
of this assumption, formulations containing 100 g. of
dioctyl phthalate, 1 g. of azobisformamide, 1.8 g. di~n-~utyltit ,-
S,S'_bis(isooctyl mercaptoacetate) and 0.2 g~ of various
organotin compounds were prepared and tested as described
in Example 1.
The organotin compounds evaluated in combination
with di-n-butyltin-S,S'-bis(isooctyl mercaptoacetate) were
dibutyltin sulfide, monobutyltin trichloride, dibutyltin
oxide and dibutyltin maleate. The latter compound enhances
the performance of di-n-butyltin-S,S'-bis(dodecyl mercaptide).
None of theæe formulations had yielded more than 50 c.c. of
gas when the temperature of the mixture reached 180C. By
contrast, the formulation containing 2 g. of di-n-butyltin-
S,S'-bis(isooctyl mercaptoacetate) and no other organotin
compound produced 105 c.c. of gas under the same conditions.
_18_
1049700
EXAMPLE 3
This exampLe demonstrates the further improvement
in bLowing agent activation obtained when a diorganotin
dimercaptide of this invention, dibutyltin-S,S'-bis(tr-i~ecyl
mercaptide), is employed in combination with a) a mono- or
diorganotin derivative of a carboxylic acid andfor b) a zinc
salt of a carboxylic acid. The formulations were prepared
and tested as described in Example 1. Unless otherwise
indicated, the weight ratio of the organotin mercaptide
L0 to the other organotin compound was 9:1, respectively, the
total amounting to 2 grams per 100 grams of dioctyl phthalate.
Dibutyltin dilaurate at a concentration of 2 parts
per 100 parts of plasticizer and in the absence of an organotin
mercaptide was evaluated as a control. The formulation had
produced only 54 c.c. of gas when the temperature reached
180C. The yield of gas was 117 c.c. at a temperature of
190C.
10~9700
TABLE III
..
ACTIVATOR- 1.8 g. of Total Volume of Gas (in c.c.) Evolved
dibutyltin bis(tri- When Temperature of Mixture Reached
dodecyl mercaptide)
~ 0.2 g. of co-activator 160C.170C. 180C. 190C.
. -
2inc Octanoate 18 75 205 245
Dibutyltin dilaurate15 50 130 7240
Dibutyltin bis(isooctyl
maleate 18 54 134 7240
Monobutyltin tris
(dodecyl maleate) 12 28 . 94 225
Monobutyltin tris
(dodecyl malea~e) ~
zinc octanoate 15 65 175 245
Dibutyltin dilaurate + ,
zinc octanoatel 25 80 190 7240
Dibutyltin dibutoxide 18 75 2 00 7240
_ , . . .
1 1:1 weight ratio mixture
2 Dibutyltin bis(dodecyl mercaptid~) used in place of
dibutyltin bis(tridecyl mercaptide)
.
. --- - , . .
1049700
EXAMPLE 4
. This example demonstrates other representative
organotin mercaptides which are suitable for use as
activator-stabiLizers in the preparation of celluLar vinyl
chloride polymers. Formulations containing dioctyl phthalate,
azobisformamide and the organotin compound were prepared
and tested as described in Example 1. The results of the
evaluations are summarized in the following table.
TABLE IV
Activator Total Volume of Gas (c.c.) Collected
When the Temperature Reached
160C. 170C. 180C.190C.
dibutyltin-S,S'-bis
(benzyl mercaptide) 5 50 135 222
15 dimethyltin-S,S'-bis
(dodecyl mercaptide)10 32 1957240
_ ,
. . . ~: .. --.
... . ., ~.. .-- : . .. . .
1049700
EXAMpTF 5
This example demonstrates the efficacy of the
present activator-stabiliæers in promoting decomposition of
another commercial blowing agent, p-toluene sulonyl
semicarbazide. The formulation employed for the evaLuation
contained 100 parts of dioctyl phthalate, 1.0 part of the
blowing agent and 2.0 part of the organotin compound. The
formulation was heated from ambient to about 250C. at a
rate of 5C. per minute, and the amount of gas evolved was
me,asured as described in Example 1, and is recorded in the
following table. The results obtained using dibutyltin-S,S'-
bis(isooctyl mercaptoacetate) are included for purposes
of comparison.
TABLE V
Activator Total Volume of Gas (C.C.) Collected When
the Temperature Reached c
160C. 180C. 190C. 200C. 210C. 220C. 2 oo
_ _
None 1 2 4 10 22 44 1 0
dibutylti -S,S'-
bis'IOMA ~ 10 13 15 25 75 127 1 5
(control)
dibutyltin-S,S'-
bis(dodecyl 10 13 20 45 105 140 1 5
mercaptide)
dibutyltin-S,S'-
bis(dodecyl 13 20 60 125 153 1 5
~ dibutyltin 2
dilaurate (10%)
_ .
1 IOMA = isooctyl mercaptoacetate
2 total activator content = 2 parts --
_22_
- . ~ .. ,,.:, .... - ,. : .. . ~ : : -
10~9700
EXAMPLE 6
This example demonstrates the improvement in both
static and dynamic stability of vinyl chloride polymers
containing the activator-stabilizers of this invention.
The stability of a conventionaL formulation
employed to prepare ceLlular polymer was evaluated by blending
the formulation on a 2-roll differential speed mill heated to
a temperature of 165C. until a homogeneous sheet was
obtained. The sheet was then removed from the mill. Test
specimens in the form of squares measuring 1 inch (2.5 cm.)
along each side were cut from the sheet and placed in a
circulating air oven that was maintained at a temperature
of 190C.
Samples were withdrawn at 5 or 10 minute intervals
for a color evaluation. The results of the evaluation are
recorded in the following Table VI. The formulation employed
to prepare the test specimens contained:
Parts by Weight
Vinyl Chloride Homopolymer (~_inherent=0.8) 100.0
Calcium carbonate (Omyalite* 90 T) 6.0
Processing acid(acrylic polymer, K-120 N)3.0
Acrylonitrile-butadiene-styrene terpolymer3.0
(Blendex 401)
Titanium dioxide 2.0
Azobisformamide blowing agent 1.0
Paraffin Wax (m.p.= 93C.) 0.8
Calcium Stearate 0.5
Stabilizer (as shown in Table VI) 2.0
* Trademark
- ,. . - . .
1049700
The stabilizers in Table VI are designated by
letters as follows:
D - dibutyltin-S,S'-bis~isooctyl mercaptoacetate)
. (control)
E - A mixture of barium and cadmium carboxylates
containing 7% Ba and 14% Cd (available as
Nuostabe V-133*from Tenneco ChemicaLs, Inc.).
F - A 90:10 weight ratio mixture of dibutyltin-
S,S'-bis(tridecyl mercap~ide) and dibutyltin
dilaurate, respectively. . .
TABLE VI
Time Stabilizer
(Min.) D (control) E (control) F
0 White-yellow Pink White
YelLow-r~hite Pink White
10 Light-Jellow Pink(yellow tinge) White
Yellow Yellow(pink tinge) White-yellow
Dark Yellow Dark Yellow Light-yellow-brown
Yellow-brown Dark brown Yellow brown
Light brown Very dark brown Brown
The foregoing data clearly indicate the improved
effectivenes~ of the present activator-stabilizers over
prior art materials. .
The dynamic stability imparted by one of the present
activator-stabilizers, a 90:10 weight ratio mixture of .
dibutyltin-S,S'-bis(tridecyl mercaptide) and dibutyltin
dilaurate, respectively, was compared with that of formulations
containing stabilizers D and E of Table VI. The formulation
employed was identical to that disclosed in the first part
of this example, with the exception that the vinyl chloride
homopolymer exhibited an intrinsic viscosity of 0.78 and
was identified as Geon 110 x 223 (available from B. F.
Goodrich Chemical Corporation).
¦ ~ Tr~e rk _24_
Il I
~_ -, '
1049700
The formulations were evaluated by placing each
one individually into the chamber of a mixing bowL attached
to a Plasticorder torque rheometer manufactured by C. W~
Brabender Instruments, Inc. The temperature within the
mixing bowl chamber was 200C. and the two rotors turned
in opposite directions at speeds of 60 and 40 revolutions
per minute. The torque required to maintain the rotors at
a constan~ speed was recorded on a graph as a function of
time. The torque increased abruptly when the formulation
was placed ln the mixing bowl chamber and reached a maximum
value within about one or two minutes. This maximum value
gradually decreased as the formulation fused and the
viscosity of the resultant melt decreased. There was a
noticeable increase in the torque as the polymer began
to decompose and cross-link. The period of time between `
fusion, i,e. liquefaction of the formulation, and the point
at which the torque first exhibited an increase due to
decomposition of the polymer was measured and i8 recorded
below. The stabilizers are designated A, B and C as
defined in Example 1 of this specification.
TABLE VII
Activator-Stabilizer Stabilization Period(minutes)
. , ~
A 19.9
B 15.1
C 19.6
* Trade mark
~25_
