Organotin mercapto dicarboxylic acid esters and compositions

Organotin mercapto dicarboxylic acid esters are provided having either substantially no odor or a remarkably low odor, and capable of imparting to polyvinyl chloride resin compositions when heated at elevated temperatures an enhanced resistance to early discoloration as well as an enhanced resistance to long term discoloration, without any obnoxious mercaptide odors. A process is provided for preparing organotin mercapto carboxylic acid esters by reaction of a monohydric alcohol or mixed monohydric alcohol-glycol mercapto dicarboxylic acid ester with an organotin oxide or halide, and then, if the mercapto dicarboxylic acid ester is of a monohydric alcohol only, transesterifying this reaction product with a glycol. Polyvinyl chloride resin compositions are also provided containing such organotin mercapto carboxylic acid esters, and having an enhanced resistance to both early and long term discoloration, without any obnoxious mercaptide odor.

The stabilizing effectiveness of organotin stabilizers for polyvinyl 
chloride resins is generally associated with the structure of the 
organotin groups, a high tin content, and a high sulfur content. For 
optimum stabilizing effectiveness, all three features become prerequisites 
and each must be optimum, as well. The manner in which the organotin, tin 
and sulfur groups are associated in the molecule, however, appears to be 
more important than high proportions of tin and sulfur. 
The organotin sulfides, for example, offer the highest tin and sulfur 
contents per organotin group, and yet they are not the best stabilizers, 
and have never found a place as a commercial stabilizer, since they do not 
impart resistance to development of early discoloration. Despite their 
considerably lower tin and sulfur contents, the most effective organotin 
stabilizers presently in widespread use, and the recognized standard for 
judging other organotin stabilizers, are the organotin mercapto carboxylic 
acid esters. Despite their stabilizing effectiveness, however, the 
organotin mercapto carboxylic acid esters have several serious 
disadvantages. 
A further problem associated with the organotin mercapto carboxylic acid 
esters, especially the dialkyl tin thioglycolate esters, is their tendency 
to crystallize or precipitate when formulated in liquid polyvinyl chloride 
resin stabilizer compositions. 
The formation of a crystalline precipitate is due to hydrolysis of the 
organotin thioglycolate ester to form a cyclic compound that is insoluble 
in the system. The cyclic compound is not an effective stabilizer, and 
therefore its formation depreciates if not destroys the effectiveness of 
the organotin mercapto carboxylic acid ester as a stabilizer. 
Attempts have been made to overcome this difficulty. Hecker in U.S. Pat. 
No. 2,789,963, patented Apr. 23, 1957 and Hoch in U.S. Pat. No. 3,655,703, 
patented Apr. 11, 1972, suggest the addition of various additives. These 
are helpful, but they merely delay and do not entirely prevent the 
formation of crystalline precipitates. 
A further problem with the organotin mercapto carboxylic acid esters is 
their odor, which to some tastes can only be described as appalling. This 
ordor is so obnoxious that during processing, even under ventilation, the 
order cannot be removed, and remains with the finished resin articles for 
a long time. 
H. Verity Smith in his pamphlet entitled The Development of the Organotin 
Stabilizers, page 19, refers to this ordor, but the fact is that because 
of their stabilizing effectiveness the organotin mercapto carboxylic acid 
esters have been doggedly endured. This is partly because the other 
organotin stabilizers that are available either have a worse odor, or are 
considerably less effective, so that their use in sufficiently large 
amounts posed other and more difficult problems. 
A further problem with the organotin mercapto carboxylic acid esters is 
their inability to entirely prevent an early yellow discoloration in the 
resin, which is manifested before severe heat deterioration really sets 
in. Weisfeld U.S. Pat. No. 3,640,650, patented Feb. 8, 1972 proposed the 
use of mono alkyl tris (alkyl thioglycolates) in an attempt to improve 
early color. This early discoloration has not been considered 
disadvantageous for many uses, and the efforts of most workers in this 
field have been directed towards minimizing the onset of the more serious 
heat deterioration which sets in during long heating, as in milling. 
However, because of this discoloration, and the accompanying haziness that 
may also appear, it has not been possible in all cases to obtain a 
substantially clear and colorless polyvinyl chloride resin composition 
using these stabilizers. 
There has been a need for a PVC stabilizer that will provide a compound 
having no initial discoloration or yellowing, and maintaining this freedom 
from early yellowing through its manufacturing cycle of five to fifteen 
minutes, as for instance, in PVC containers such as bottles. This is 
because the average period of time during which a given amount of resin 
product remains in the processing equipment, even in a continuous process 
which includes recycling of portions of the worked product, is less than 
fifteen minutes. Only a minor proportion of the resin will be subjected to 
working temperatures for periods of up to one-half hour or longer. Hence, 
the preservation of a good color and clarity during the first fifteen 
minutes of heating can be more difficult than the protection of the 
relatively small proportion of the resin by long term heat stabilizers, 
such as the organotin mercapto carboxylic acid esters. 
The use of the organotin mercapto carboxylic acid esters as stabilizers for 
polyvinyl chloride resins is well known, and is set forth in such early 
patents as U.S. Pat. No. 2,752,325 to Leistner et al., patented June 26, 
1956, 2,641,596 to Leistner et al, patented June 9, 1953, and 2,648,650 to 
Weinberg et al, patented Aug. 11, 1953. 
Similar disclosures of polymeric organotin compounds, which generally 
include a chain of tin atoms connected through oxygen or sulfur atoms, are 
set out in U.S. Pat. Nos. 2,597,920, patented Apr. 15, 1962; 2,626,953, 
patented Jan 27, 1953; 2,628,211, patented Feb. 10, 1953; 3,184,430 
patented May 18, 1965; and 2,938,013, patented May 24, 1960. 
U.S. Pat. No. 2,809,956, patented Oct. 15, 1957, discloses polymeric 
organotin compounds which include mercapto ester groups attached to tin, 
having the general formula: 
##STR1## 
wherein SX can be mercapto; mercapto alcohol or ester; or mercapto acid 
ester groups. These compounds, however, have been found not to be as 
effective stabilizers as the monomeric organotin mercapto carboxylic acid 
esters, such as dibutyltin bis-(isooctyl thioglycolate). 
Weinberg and Johnson U.S. patent No. 2,832,752, patented April 29, 1958, 
describe organotin compounds which are condensation products with 
polycarboxylic mercapto acids and esters containing the group 
##STR2## 
The class of compounds in question is indicated by the formula 
EQU R.sub.n Sn(SR'(COOR").sub.m).sub.4-n .vertline. 
where R is aryl, alkyl or alkaryl, such as methyl, ethyl, butyl, propyl, 
phenyl, tolyl, benzyl, etc.; R' is aliphatic hydrocarbon radical, R" is 
hydrogen, aryl, alkyl, alkaryl or cyclic, saturated or unsaturated, m is 
an integer not less than 2, and n may be 1, 2, or 3. Among the groups from 
which R" may be selected are isooctyl, 2-butyloctyl, butyl, cyclohexyl, 
dihydroabietyl, benzyl, phenyl, cresyl, allyl. Among the polycarboxylic 
acids and their esters which may be employed in this invention are 
thiomalic acid, .alpha.-mercaptoadipic acid, and their appropriate esters. 
Example II provides dibutyltin-S,S'-bis-(thiomalic acid) and Example I, 
dibutyltin-S,S'-bis(dibutyl thiomalate), the former a low-melting solid, 
and the latter a viscous amber liquid, both of which were however quite 
deficient in tin and sulfur as compared to the theoretical tin and sulfur 
contents of the compounds hypothecated. Clearly, the compounds did not 
correspond to this structure because the tin and sulfur contents were far 
too low. Dibutyltin-S,S'-bis(thiomalic acid) even when prepared to 
substantially the correct analysis does not give the freedom from early 
yellow discoloration and the longterm heat stabilization of the compounds 
of this invention. The theoretical values for dibutyltin-S,S'-bis-(dibutyl 
thiomalate) are 15.8% Sn and 8.5%S, or roughly double the quantities found 
by Weinberg et al for this product. 
This type of organotin thiomalate ester has a foul ordor, similar to the 
organotin mercapto carboxylic esters, and definitely no improvement. These 
compounds likewise do not overcome the deficiency in the organotin 
mercapto carboxylic esters of not providing an enhanced resistance to 
early discoloration. 
Mack and Parker U.S. Pat. No. 2,914,506, patented Nov. 24, 1959, provides 
organotin mercaptides of the formula 
##STR3## 
wherein R, R', SX and Z have the following significance: R and R' may be 
different monovalent hydrocarbon radicals, but will be generally the same 
radicals, because the starting materials for the preparation of the 
organo-tin mercapto compounds will be generally the di-(or tri-) 
hydrocarbon tin halides or oxides available in commerce. The nature of 
these groups has in most cases no, or only a very minor, influence on the 
properties of the end products. R and R' may be aliphatic, aromatic, or 
alicyclic groups, such as methyl, ethyl, propyl, butyl, amyl, hexyl, 
octyl, lauryl, allyl, benzyl, phenyl, tolyl, cyclohexyl. 
SX may be, for instance, the rest of a mercaptan, of a mercapto alcohol, or 
of an ester of a mercapto alcohol or mercapto acid. 
Readily available mercapto acid esters are the esters of thioglycolic acid, 
such as ethyl thioglycolate, and generally the esters of mono and dibasic 
aliphatic and aromatic mercapto acids, such as esters of beta 
thiopropionic acid, thiolactic acid, thiobutyric acid, alpha mercapto 
lauric acid, thiomalic acid, thiosalicylic acid, and the like. 
Z may have the same composition as SX. Thus, the broad class of compounds 
defined by this formula encompass the organotin thiomalate esters of the 
type disclosed by Weinberg et al in U.S. Pat. No. 2,832,752, but in fact 
no organotin thiomalate esters are named or disclosed in any working 
Example. A compound R.sub.2 SN(SX)Z where R is n-butyl, SX is derived from 
dibutyl thiomalate and Z is derived from isooctyl thioglycolate, an 
instance of the compounds shown in U.S. Pat. No. 2,914,506, was lacking in 
the ability to prevent early yellow discoloration and also formed a 
precipitate within 50 days storage at room temperature. 
Brecker U.S. Pat. No. 3,565,931, and Kauder No. 3,565,930, both patented 
Feb. 23, 1971, describe organotin mercapto carboxylic acid ester sulfides 
having a high concentration of tin, in the range from about 18 to about 
35% by weight, and a high concentration of sulfur, within the range from 
about 10 to about 25% sulfur. These compounds have a relatively high 
concentration of tin and sulfur, compared to the organotin mercapto 
carboxylic acid esters, and are said to improve the initial color of a 
resin composition during the first 30 minutes of heating, and to also 
improve the long term stability before final charring. However, the odor 
of these compositions offers no advantage over the organotin mercapto 
carboxylic acid esters. 
Cohen U.S. Pat. No. 3,627,716, patented Dec. 14, 1971, and Brecker No. Pat. 
No. 3,642,677, patented Feb. 15, 1972 describe stabilizer compositions for 
polyvinyl chloride resins comprising an organotin mercapto carboxylic acid 
ester, a bivalent stannous tin salt, and, optionally, a diorganotin oxide. 
The stannous salts are acid to impart to the organotin mercapto carboxylic 
acid esters the ability to improve the resistance of polyvinyl chloride 
resins to the development of early discoloration when heated at elevated 
temperatures. 
In accordance with the present invention, organotin mercapto dicarboxylic 
acid esters and especially organotin thiomalate esters are provided having 
either substantially no odor or a remarkably low odor, that prevent the 
development of early discoloration of polyvinyl chloride resins when 
heated at elevated temperatures. The organotin thiomalate esters of the 
invention are superior in these respects to the organotin mercapto 
carboxylic acid esters. In addition, these organotin thiomalate esters 
show no tendency to crystallize or develop precipitates in liquid 
stabilizer compositions for polyvinyl chloride resins. 
In total stabilizing effectiveness they are superior to the organotin 
mercapto carboxylic acid esters. Thus, these organotin thiomalate esters 
are unsually advantageous stabilizers for polyvinyl chloride resin 
compositions. Other organotin mercapto dicarboxylic acid esters are 
advantageous in these respects as well, such as organotin mercapto methyl 
succinic acid esters. 
The organotin mercapto dicarboxylic acid esters of the invention are mixed 
monohydric and polyhydric alcohol esters of organotin mercapto 
dicarboxylic acid salts having per tin atom one or two alkyl, cycloalkyl, 
or alkylcycloalkyl groups attached to tin through carbon, and having from 
one to about twelve carbon atoms; and two or three mercapto dicarboxylic 
acid ester groups attached to tin through sulfur, the mercaptodicarboxylic 
acid having from about 4 to about 24 carbon atoms, and having at least one 
esterifying group selected from the group consisting of alkyl, cycloalkyl, 
and alkylcycloalkyl having from one to about 12 carbon atoms, and at least 
one esterifying group selected from the group consisting of bivalent 
alkylene, cycloalkylene and alkylenecycloalkylene having from about 2 to 
about 12 carbon atoms, such bivalent groups linked to hydroxyl, and such 
bivalent groups linked to a second organotin mercapto dicarboxylic acid 
ester group. These compounds have been assigned the following general 
formula: 
##STR4## 
wherein m.sub.1 and m.sub.3 are numers within the range from 0 to about 7; 
m.sub.2 is a number within the range from 1 to about 7; 
n is 1 or 2; 
R is selected from the group consisting of alkyl, cycloalkyl, and 
alkylcycloalkyl having from one to about twelve carbon atoms linked to tin 
through carbon; and 
at least one of Z.sub.1 and Z.sub.2 is selected from the group consisting 
of alkyl, cycloalkyl and alkylcycloalkyl having from three to about 12 
carbon atoms; 
and at least one of Z.sub.1 and Z.sub.2 is selected from the group 
consisting of 
i. bivalent alkylene, cycloalkylene and alkylenecycloalkylene having from 
two to about twelve carbon atoms; 
ii. hydroxyalkyl, hydroxycycloalkyl and hydroxyalkylcycloalkyl having from 
two to about twelve carbon atoms; and 
iii. bivalent alkylene, cycloalkylene and alkylenecycloalkylene having from 
about two to about twelve carbon atoms and linked to a second organotin 
mercapto dicarboxylic acid ester group of Formula 1 via an ester group 
thereof of the form: 
##STR5## 
iv. bivalent alkylene, cycloalkylene, and alkylenecycloalkylene linked to 
a second organotin thiomalate group of Formula I via an ester group 
thereof of the form: 
##STR6## 
It will be apparent that when m.sub.1 and m.sub.3 are 0 and m.sub.2 is 1, 
the ester is a thiomalate ester. The thiomalate esters are preferred. When 
m.sub.1 and m.sub.2 are 1 and m3 is 0, the ester is a 
mercaptomethylsuccinate ester. When m.sub.1, m.sub.2, and m.sub.3 are each 
1, the ester is a .beta.-mercaptomethyl glutarate ester, and when m.sub.1 
is 0, and m.sub.2 and m.sub.3 are each 1, the ester is a 
.beta.-mercaptoglutarate ester. Similarly, .alpha.-mercaptoglutarate, 
.alpha.-and .beta.-mercaptoadipate, .alpha.-, .beta.- and .gamma.- and 
.delta.-mercaptoazelate and mercaptosebacate esters are obtained. 
When m.sub.1 and m.sub.3 are 0, m.sub.2 is 1, and when 
(1) n is 1, the compounds take the form 
##STR7## 
and when 
(2) n is 2, the compounds take the form: 
##STR8## 
In these formulae, Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4, Z.sub.5 and Z.sub.6 
are the same as Z.sub.1 and Z.sub.2 as defined above. 
It will be apparent from the above that when Z.sub.1, Z.sub.2, Z.sub.3, 
Z.sub.4, Z.sub.5 and Z.sub.6 are all either monoalkyl, monocycloalkyl, or 
monoalkylcycloalkyl of (i), or hydroxyalkyl, hydroxycycloalkyl or 
hydroxyalkylcycloalkyl, m.sub.1 and m.sub.3 are 0 and m.sub.2 is 1, the 
formula takes one of the two forms, according to whether n is 1 or n is 2: 
##STR9## 
wherein: 
R.sub.1 and R.sub.2 are selected from the group consisting of alkyl, 
cycloalkyl or alkylcycloalkyl having from one to about 12 carbon atoms; 
and 
R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 (and R.sub.10 and 
R.sub.11 below) are selected from the group consisting of alkyl, 
cycloalkyl and alkylcycloalkyl having from 1 to about 12 carbon atoms; and 
hydroxyalkyl, hydroxycycloalkyl, and hydroxyalkylcycloalkyl having from 2 
to about 12 carbon atoms. 
When one of Z.sub.1 and Z.sub.2 ; Z.sub.3 and Z.sub.4 ; and Z.sub.5 and 
Z.sub.6 is monovalent alkyl, cycloalkyl or alkylcycloalkyl, and the other 
two Z's are taken together as a bivalent alkylene cycloalkylene or 
alkylcycloalkylene, m.sub.1 and m.sub.3 are 0, and m.sub.2 is 1, the 
formula takes one of the two forms according to whether n is 1 or n is 2: 
##STR10## 
wherein 
R.sub.1, R.sub.2, R.sub.3, R.sub.6, R.sub.10 and R.sub.11 are as above, and 
R.sub.9 is a bivalent alkylene, cycloalkylene or alkylenecycloalkylene 
group having from 2 to about 12 carbon atoms. 
When one of Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4, Z.sub.5 and Z.sub.6 is an 
alkylene, cycloalkylene or alkylenecycloalkylene group linked to a second 
organotin thiomalate group, m.sub.1 and m.sub.3 are 0, and m.sub.2 is 1, 
the formula takes one of the two forms, according to whethe n is 1 or n is 
2: 
##STR11## 
wherein: 
R.sub.1, R.sub.2, R.sub.3, R.sub.5 and R.sub.6 are as above and R.sub.9 is 
a bivalent alkylene, cycloalkylene or alkylenecycloalkylene group having 
from 2 to about 12 carbon atoms. 
When two of Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4, Z.sub.5 and Z.sub.6 are 
bivalent alkylene, cycloalkylene or alkylenecycloalkylene groups linked to 
a second organotin thiomalate group, m.sub.1 and m.sub.3 are 0, and 
m.sub.2 is 1, the formula takes one of the two forms, according to whether 
n is 1 or n is 2: 
##STR12## 
wherein: 
R.sub.1, R.sub.2, R.sub.5, R.sub.6 and R.sub.9 are as above. 
It is also possible to obtain polymers in the case where the glycol reacts 
with carboxylic acid or ester groups of different organotin thiomalate 
ester molecules, of the types: 
##STR13## 
In these polymers, m is a number, which can represent an average number, 
within the range from about 1 to about 20, but usually not exceeding about 
10, and R.sub.1, R.sub.2, R.sub.6, R.sub.9, R.sub.10 and R.sub.11 are as 
above. 
Other variations within the general Formula I will be apparent to those 
skilled in this art, but the above variations II to VI exemplify preferred 
embodiments of the organotin thiomalate esters of the invention. Similar 
embodiments exist of the other organotin mercapto dicarboxylic acid 
esters. 
Exemplary Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4, Z.sub.5, Z.sub.6, R.sub.1, 
R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, 
and R.sub.11 alkyl groups include methyl, ethyl, n-propyl, isopropyl, 
n-butyl, secondary butyl, tertiary butyl, isobutyl, isoamyl, secondary 
amyl, and tertiary amyl, n-hexyl, isohexyl, n-heptyl, n-octyl, isooctyl, 
2-ethyl hexyl, n-nonyl, n-decyl, n-undecyl and n-dodecyl. The octyl 
isomers are preferred for Rn- Sn- when the organotin thiomalate esters of 
the invention are to be utilized in foodstuff applications, because of 
their low toxicity. 
Exemplary cycloalkyl cycloalkyl groups include cyclopentyl, cyclohexyl, 
cyclobutyl, cyclopropyl, cycloheptyl, cyclooctyl, and cyclododecyl. 
Alkylcycloalky groups include ethyl cyclohexyl, diethylcyclohexyl, tetra 
methyl cyclohexyl, propyl, cyclopentyl, methyl cyclopentyl, tetra methyl 
cyclopentyl, trimethyl cyclobutyl, and diethyl cycoheptyl. 
The Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4, Z.sub.5, Z.sub.6, R.sub.3, R.sub.4, 
R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, and R.sub.11 hydroxyalkyl 
groups are derived from alkylene glycols having from two to about twelve 
carbon atoms, for example, ethylene glycol; 1,2- and 1,3- propylene 
glycol; 1,2-; 2,3-; 1,3-; and 1,4- butylene glycol; 1,2-; 2,3-; 2,4:; 
1,5-; and 1,4- amylene glycol, 1,6- hexylene glycol, 2,4-dimethyl 
pentanediol, dodecylene glycol, decylene glycol, and octylene glycol; and 
cycloalkylene and alkylenecycloalkylene glycols having from three to about 
twelve carbon atoms, for example, cyclobutylene glycol, cyclopentylene 
glycol, cyclohexylene glycol, cycloheptylene glycol, cyclooctylene glycol, 
1,4-cyclohexane dimethanol, 1,4-bis-(methylene) cyclohexylene glycol, 
1,3-bis-(ethylene) cyclopentylene glycol, and 1,4-bis-(methylene heptylene 
glycol, in which only one of the two hydroxyl groups is esterified with a 
thiomalic acid ester group. 
If both hydroxyl groups of the glycol are esterified with thiomalic acid 
ester groups, the compounds are dimers or higher polymers having two or 
more organotin units, and are of the type of Formulas IV, V and VI above, 
or have heterocyclic rings of the type of Formula III, above. 
The organotin mercapto dicarboxylic acid esters of the invention are 
readily prepared by two routes. In one route, the corresponding organotin 
halide is reacted with a monohydric alcohol mercapto dicarboxylic acid 
ester, followed by transesterification with the desired glycol. The 
reaction proceeds in accordance with the following scheme: 
##STR14## 
In the second route, the mixed monohydric alcohol glycol mercapto 
dicarboxylic acid ester is reacted with organotin oxide, or organotin 
halide with acid acceptor. The compounds of Formulae II, II, IV, V, and VI 
are then obtained in one step. 
When an organotin halide is used with an acid acceptor, the halide can be 
chloride, bromide or iodide, and the acid acceptor can be any of ammonium, 
sodium, potassium, lithium, calcium, and magnesium hydroxides, carbonates, 
and bicarbonates, in aqueous or non-aqueous media. In a non-aqueous 
reaction medium (no solvent at all or any convenient organic solvent), the 
halide salt side product can be removed by filtration or subsequent water 
washing. 
Organotin intermediates other than halides or oxides also can be used, 
including the adducts of ammonia and organic amines with dialkyltin 
dichlorides, for example Bu.sub.2 SnCl.sub.2 . 2NH.sub.3, used preferably 
in an organic solvent medium from which the ammonium chloride side product 
is filtered off, also dialkyltin dialcoholates such as dibutyltin 
dimethoxide (from which alcohol side product can be distilled or washed 
out) or organotin salts of low molecular weight carboxylic acids, e.g. 
dibutyltin diacetate and tetrabutyl diacetoxy distannoxane, from which 
acetic acid side product can be distilled or washed out. 
It will be apparent that the direction of the reaction towards formation of 
any particular compound or mixture of Formulae II, III, IV, V, VI is 
determined by the relative molar proportions of the reactants, according 
to conventional principles of stoichiometry. 
While stoichiometric proportions can be used, according to the product 
desired, it may be advantageous to depart to some extent from such 
proportions. Where an excess of mercapto dicarboxylic acid ester is used, 
the resulting product is a mixture of the organotin compounds 
stoichiometrically expected with the excess mercapto dicarboxylic acid 
ester. Excess organotin compound reagents on the other hand can give a 
variety of products. 
When the organotin compound reagent is an organotin oxide, a greater than 
equivalent amount of oxide can react with an equivalent of mercapto 
dicarboxylic acid ester to form an overbased product that can be 
formulated either as an adduct: 
##STR15## 
and similarly for RSn compounds. 
A reaction product of dibutyltin oxide with thiomalate ester containing 
S:Sn ratio of 1:1 mixed with one more equivalent of mercapto dicarboxylic 
acid ester give the product of Formula I. By the same technique, many 
different S:Sn ratio products between 1:1 and 2:1 can be prepared, and 
good heat stabilizing activity is obtainable at least in the range of 
1.3:1 S:Sn and up. 
When the organotin compound reagent is an organotin chloride, and a greater 
than equivalent amount is used with the mercapto dicarboxylic acid ester, 
different kinds of product can be obtained, depending on the amount of 
alkali used. If the amount of alkali is exactly equivalent to the amount 
of mercapto dicarboxylic acid ester, the excess chloride will remain as 
Cl-SnR.sub.2 -S- or 
##STR16## 
if the amount of alkali is equivalent to the amount of chloride, i.e. 3 
moles per RSnCl.sub.3 and 2 moles per R.sub.2 SnCl.sub.2, then the 
products will be the overbased materials obtained with organotin oxide in 
excess; finally, if the amount of alkali is more than equivalent to the 
amount of mercapto dicarboxylic acid ester and less than equivalent to the 
amount of organotin chloride, some of each kind of product will be formed. 
The reaction of the thiomalic acid ester with the organotin oxide or halide 
is conventional, and proceeds in the presence or absence of a solvent, at 
a moderate temperature, within the range from about 25 to about 
150.degree. C, in a relatively short time, of the order of from 20 minutes 
to 3 hours. According to the value of n in Formula I, two or three moles 
of the mercapto dicarboxylic acid are used per mole of organotin oxide 
halide. Any halide can be used, but the chloride, bromide and iodine are 
more readily available, and would generally be employed. 
The transesterification reaction proceeds at an elevated temperature within 
the range from about 75.degree. to about 200.degree. C, in the absence of 
a catalyst, with removal of the monohydric alcohol that is displaced by 
the glycol in the course of the transesterification. Removal of the 
monohydric alcohol by distillation, preferably by vacuum stripping, 
ensures that the transesterification reaction proceeds to completion. As 
the reaction proceeds, the reaction mixture usually increases in 
viscosity. 
The rate of transesterification may be increased in the presence of 
transesterification catalyst, such as an acid or a base, for example, 
p-toluene sulfonic acid. 
The following Examples represent preferred embodiments of the organotin 
mercapto carboxylic acid esters in accordance with the invention and their 
preparation.

EXAMPLE I 
Two moles (524 g) dibutyl thiomalate and one mole dimethyltin dichloride 
(220 g) were mixed and two moles aqueous 10% sodium hydroxide solution 
then added slowly. The reaction temperature was held at 60.degree. C for 
one half hour after the addition of the sodium hydroxide solution was 
complete. The final pH of the reaction mixture was 5.7. 
The mixture was separated easily at 60.degree. C in a separatory funnel. 
The organic portion, the lower layer, was dried and vacuum stripped at 20 
to 25 mm of mercury to a maximum pot temperature of 60.degree. C. When all 
of the water had been removed, the product was filtered, giving a clear, 
light product, identified as dimethyltin bis-(dibutyl thiomalate). 
The dimethyltin bis-(dibutyl thiomalate) was then mixed with ethylene 
glycol as noted in Table I below in the proportion of one mole ethylene 
glycol per mole of dimethyltin bis-(dibutyl thiomalate), and the mixture 
then heated for three hours at from 120.degree. to 125.degree. C. At the 
conclusion of this reaction time, the butanol liberated in the course of 
transesterification with ethylene glycol was removed by vacuum-stripping 
to 130.degree. C maximum pot temperature. 
As the reaction proceeded, and the initially immiscible ethylene glycol was 
transesterified, the reaction mixture became clear, and after the removal 
of butanol remained clear. In the course of vacuum-stripping, unreacted 
ethylene glycol was also distilled off, and consequently the 
transesterification product was considered to be free of both unreacted 
ethylene glycol and butanol. 
Four runs were made under these conditions, with the following results: 
TABLE I 
______________________________________ 
Butanol Distilled 
Butanol Distilled 
Moles Per Mole Of 
Moles Per Mole 
Dimethyltin Bis- Of Ethylene 
Run No. (Dibutyl Thiomalate) 
Glycol Reactant 
______________________________________ 
Run 1 1.22 1.22 
Run 2 1.52 1.52 
Run 3 0.70 1.09 
Run 4 1.45 1.45 
______________________________________ 
EXAMPLES II TO VIII 
Two moles (524 g) dibutyl thiomalate and one mole dibutyltin oxide (249 
g)(in Example III, a 1:1 mixture of dibutyltin oxide and monobutyltin 
oxide was used instead) were mixed, and the reaction mixture held at 
60.degree. C for one half hour after the addition of the oxide was 
complete. The reaction mixture was dried and vacuum-stripped at 20 to 25 
mm of mercury to a maximum pot temperature of 90.degree. C. When all the 
reaction water had been removed, the product was filtered, giving a clear, 
light product, identified as dibutyl bis-(dibutyl thiomalate) (or, in 
Example III, a 1:1 mixture of this with monobutyltin tris-(dibutyl 
thiomalate)). 
The dibutyltin bis-(dibutyl thiomalate) or, in Example III, a 1:1 mixture 
of this with monobutyltin tris-(dibutyl thiomalate) was then mixed with 
the alkylene glycol noted in Table II below in the proportion noted of 
alkylene glycol per mole of dibutyltin bis-(dibutyl thiomalate) (or, in 
Example III, a 1:1 mixture of this with monobutyltin tris-(dibutyl 
thiomalate)) and the mixture then heated for three hours at from 
120.degree. to 125.degree. C. At the conclusion of this reaction time, the 
butanol liberated in the course of transesterification with the alkylene 
glycol was removed by vacuum-stripping to 130.degree. C maximum pot 
temperature. 
As the reaction proceeded, and the initially immiscible alkylene glycol was 
reacted, the reaction mixture became clear, and after the removal of 
butanol remained clear. In the course of vacuum-stripping, unreacted 
alkylene glycol was also distilled off, and consequently, the 
transesterification product was considered to be free of both unreacted 
alkylene glycol and butanol. 
Seven organotin thiomalate esters were made under these conditions with the 
alkylene glycols noted in Table II, with the following results: 
TABLE II 
__________________________________________________________________________ 
Butanol Distilled Moles/Mole Of: 
Alkylene Glycol Charged 
Mono Or Dibutyltin Bis 
Alkylene Glycol 
% 
Example No. 
Moles/Mole Organotin 
Or Tris (Dibutyl Thiomalate) 
Reactant Sn 
__________________________________________________________________________ 
II Ethylene Glycol 0.5 
0.74 1.48 16.0 
III Ethylene Glycol 0.5 
0.86 1.71 15.8 
IV Ethylene Glycol 1.0 
1.65 1.65 16.7 
V Ethylene Glycol 4.0 
1.98 1.225 16.3 
VI 1,3-Butylene Glycol 0.5 
0.71 1.42 15.7 
VII 1,4-Butylene Glycol 1.0 
1.83 1.83 16.4 
VIII Neopentylene Glycol 1.0 
1.45 1.45 15.5 
__________________________________________________________________________ 
EXAMPLES IX to XIII 
Two moles (524 g) dibutyl thiomalate and one mole dioctyltin dichloride 
(416 g) were mixed, and two moles aqueous 10% sodium hydroxide solution 
then added slowly. The reaction temperature was held at 60.degree. C for 
one half hour after the addition of the sodium hydroxide solution was 
complete. The final pH of the reaction mixture was 5.7. 
The mixture was separated easily at 60.degree. C in a separatory funnel. 
The organic portion, the lower layer, was dried and vacuum-stripped at 20 
to 25 mm of mercury to a maximum pot temperature of 60.degree. C. When all 
of the water had been removed, the product was filtered, giving a clear, 
light product, identified as dioctyltin bis-(dibutyl thimalate). 
The dioctyltin bis-(dibutyl thiomalate) was then mixed with the alkylene 
glycol noted in Table III in the proportion noted of alkylene glycol per 
mole of dioctyltin bis-(dibutyl thiomalate) and the mixture then heated 
for three hours at from 120.degree. to 125.degree. C. At the conclusion of 
this reaction time, the butanol liberated in the course of 
transesterification with alkylene glycol was removed by vacuum-stripping 
to 130.degree. C maximum pot temperature. 
As the reaction proceeded the initially immiscible alkylene glycol 
dissolved in the reaction mixture, and the product, after the removal of 
butanol, remained clear. In the course of vacuum-stripping, unreacted 
alkylene glycol was also distilled off, and consequently the 
transesterification product was considered to be free of both unreacted 
glycol and butanol. 
Five runs were made under these conditions with the following results: 
TABLE III 
__________________________________________________________________________ 
Butanol Distilled Moles/Mole Of: 
Glycol Charged Moles/ 
Dioctyltin Bis- Alkylene Glycol 
% 
Example No. 
Mole Organotin 
(Dibutyl Thiomalate) 
Reactant Sn 
__________________________________________________________________________ 
IX Ethylene Glycol 1.0 
0.43 0.84 13.7 
X Ethylene Glycol 1.5 
0.81 0.80 13.4 
XI Ethylene Glycol 2.0 
1.18 0.93 13.6 
XII Propylene Glycol 1.0 
0.87 1.16 
XIII 1,4-Butylene Glycol 1.0 
1.27 1.27 
__________________________________________________________________________ 
EXAMPLES XIV and XV 
Two moles (524 g) dibutyl thiomalate and one mole dimethyltin dichloride 
(220 g) were mixed and two moles aqueous 10% sodium hydroxide solution 
then added slowly. The reaction temperature was held at 60.degree. C for 
one half hour after the addition of the sodium hydroxide solution was 
complete. The final pH of the reaction mixture was 5.7. 
The mixture was separated easily at 60.degree. C in a separatory funnel. 
The organic portion, the lower layer, was dried and vacuum stripped at 20 
to 25 mm of mercury and to a maximum pot temperature of 60.degree. C. When 
all of the water had been removed, the product was filtered, giving a 
clear, light product identified as dimethyltin bis-(dibutyl thiomalate). 
The dimethyltin bis (dibutyl thiomalate) was then mixed with 1,4-butylene 
glycol or neopentylene glycol in the proportion of one mole alkylene 
glycol per mole of dimethyltin bis (dibutyl thiomalate) and the mixture 
then heated for three hours at from 120.degree. to 125.degree. C. At the 
conclusion of this reaction time, the butanol liberated in the course of 
transesterification with the alkylene glycol was removed by 
vacuum-stripping to 130.degree. C maximum pot temperature. 
As the reaction proceeded the initially immiscible alkylene glycol 
dissolved in the reaction mixture, and the product, after the removal of 
butanol, remained clear. In the course of vacuum stripping, unreacted 
1,4-butylene glycol and neopentylene glycol was also distilled off, and 
consequently the transesterification product was considered to be free of 
both unreacted alkylene glycol and butanol. 
Two runs were made under these conditions with the following results: 
TABLE IV 
______________________________________ 
Butanol Distilled 
Glycol Charged Moles/Mole Of 
Example Moles/Mole Dimethyltin Bis- 
Glycol 
No. Organotin (Butyl Thiomalate) 
Reactant 
______________________________________ 
XIV 1,4-Butylene glycol 
1.74 1.74 
XV Neopentylene glycol 
1.0 1.17 
______________________________________ 
The data for Examples I to XV show that the maximum quantity of alkylene 
glycol that reacts in this transesterification reaction is about two moles 
of glycol per mole of dialkyltin bis-(dibutyl thiomalate), and the maximum 
yield of butanol liberated in the transesterification is about 1.8 moles 
per mole of glycol reactant. This establishes that the glycol is reacting 
both as a monofunctional reagent to introduce the hydroxyalkyl group HOR 
(for example, 2-hydroxyethyl when ethylene glycol is used) as in Formula 
II above, and as a bifunctional reagent to introduce the bivalent alkylene 
group by displacement of two butyl groups linked either to another 
carboxylic acid group of the same thiomalate group or carboxylic groups of 
different thiomalate groups, as in Formulae III, IV, V and VI, above. 
The appearance of the characteristic hydroxyl group frequency in the 
infra-red absorption spectra of all of the above transesterification 
products confirms the presence of hydroxyalkyl groups. 
The data also shows that the compounds in accordance with the invention 
resulting from transesterification of dialkyltin bis-(alkyl thiomalate) 
with alkylene glycol are best represented as mixtures of compounds with 
the structural Formulae II, III, IV, V and VI, in which the first three 
predominate at relatively low glycol: organotin thiomalate ratios, and the 
last three at higher glycol: organotin thiomalate ratios. 
EXAMPLE XVI 
One mole of ethylene glycol, 2.5 moles of thiomalic acid, and 3.5 moles of 
n-butanol were reacted in a reaction vessel equipped with a reflux 
condenser and a water trap. p-Toluene sulphonic acid 3.5 g was used as an 
esterification catalyst. In the course of the reaction 94 g of aqueous 
phase was covered in the water trap and on vacuum-stripping 9 g of 
distillate was obtained, with a refractive index of 1.4076, corresponding 
roughly to a mixture of butanol (refractive index 1.3993) and ethylene 
glycol (refractive index 1.4318). The reaction product amounted to 595 g, 
and had the following properties: 
______________________________________ 
Density 25.degree. C 
1.108 
Refractive Index 
1.4717 
Gardner Viscosity 
A-4 
Perccent SH 13.28 
______________________________________ 
One mole of dibutyltin oxide (249 g) and two SH-equivalents of the above 
butyl-ethylene glycol thiomalate (498 g) were mixed and heated at 
120.degree. C with stirring and vacuum-stripping in a three-neck flask 
until the dibutyltin oxide had disappeared. This required one half hour, 
and yielded 35 ml of distillate, that separated into two layers and 
contained both water and n-butanol and a cloudy ethylene glycol-containing 
liquid product. The residue product was essentially free of butanol and 
was considered to be dibutyltin-bis-(butyl-ethylene glycol thiomalate). 
The tin content was 16.2%. Comparative storage tests were carried out with 
this product and conventional organotin stabilizers at 22.degree. to 
26.degree. C. (room temperature), as follows: 
______________________________________ 
Time to appearance 
Product of precipitate 
______________________________________ 
Example XVI None after 360 days 
Di-n-butyltin-bis (isoctyl thioglycolate) 
20 days 
Same with 5% added 40 days 
calcium 2-ethyl hexoate 
Same with 5% added 40 days 
di-isoamyl phosphate 
______________________________________ 
This remarkable freedom from precipitation over a long storage time 
represents a solution of a problem of long standing and an important 
commercial advantage. 
EXAMPLE XVII 
In a four-necked flask equipped with a condenser, stirrer, thermometer, and 
chilled receiver there was charged 2 moles of dimethyl thiomalate, 300 cc 
of benzene and 1 mole of ethylene glycol. The reaction mixture was heated 
to 100.degree.-125.degree. C with vigorous stirring and distillation until 
71 cc of methanol was obtained, thus indicating that the 
transesterification was practically complete. The resulting reaction 
mixture was cooled, and there was then added to it 2 moles of the 
dibutyltin monodimethyl thiomalate, which had been prepared by reacting 2 
moles of dibutyltin oxide with 2 moles of dimethyl thiomalate at 
110.degree.-125.degree. C. The reaction mixture was refluxed for one hour 
with stirring, and a vacuum was applied to remove the solvent. A viscous 
yellow-colored product was obtained. This product analyzed as containing 
20.9% Sn, 11.7% S, vs theoretical 21.44% Sn, 11.53% S. 
This product had the formula: 
##STR17## 
EXAMPLE XVIII 
An organotin thiomalate ester was prepared in the same fashion as described 
in Example XVI but using dibutyl thiomalate in place of dimethyl 
thiomalate. The product was a pale yellowish viscous liquid, which 
analyzed 16.6% Sn, 8.9% S, vs theoretical 17.4% Sn, 9.40% S. 
This product had the formula: 
##STR18## 
EXAMPLE XIX 
The reaction described in Example XVIII was repeated with the dibutyl 
thiomalate ester, but in place of dibutyltin oxide, dioctyltin oxide was 
used. The end product was a yellowish viscous liquid which had the 
approximate formula: 
##STR19## 
EXAMPLE XX 
The procedure of Example XVIII was followed replacing ethylene glycol with 
propylene glycol. The product obtained corresponded to the formula: 
##STR20## 
EXAMPLE XXI 
The procedure of Example XVIII was repeated using dioctyltin oxide in place 
of dibutyltin oxide. 
EXAMPLE XXII 
Freshly prepared dibutyl thiomalate (265 g of about 96% assay, 1 mole) 
containing 0.75 g toluene sulfonic acid was mixed with neopentyl glycol 
(52 g, 0.5 mole) and 100 ml benzene. The mixture was stirred and heated 
under reflux for 71/2 hours (pot temperature 116.degree. C) and then 
vacuum-stripped to 125.degree. C pot temperature and 3 mm to remove 
benzene and butanol produced by transesterification. The stripped product 
was stirred one hour at 100.degree. C with 15 g of powdered decolorizing 
carbon and filtered, to give 298 g neopentylene bis (butyl thiomalate) 
having density 1.076 at 25.degree. C,n.sub.d.sup.25.degree. 1.4455 and 
11.6% SH; molecular refractivity calculated from the observed density and 
refractive index 118.8. 
The product accordingly has been designated by the formula: 
##STR21## 
for which calculated % SH is 13.3, and molecular refractivity 116.7. 
A 48 g portion of this neopentylene bis-(butyl thiomalate) was reacted at 
135.degree. C for 45 minutes with 100 g of a 1:1 molar ratio reaction 
product of dibutylthiomalate with di-n-butyltin oxide. 
The resulting dibutyltin neopentylene bis-(butyl thiomalate) has been 
designated by the formula: 
##STR22## 
EXAMPLE XXIII 
Dibutyl thiomalate 400 g was warmed to 35.degree. C and stirred, while 
first 14.4 g monobutyltin oxide and then 164.8 g of dibutyltin oxide were 
added. 
The mixture was heated to 110.degree. C during two hours, while most of the 
oxides dissolved. Water pump vacuum was applied, and heating continued 
until the reaction mixture reached 120.degree. C to complete removal of 
reaction water. 
To the above dibutyltin-monobutyltin thiomalate was added 12 g ethylene 
glycol, and heating was continued for three hours at 
120.degree.-125.degree. C with stirring. Finally, vacuum was again applied 
to 130.degree. C maximum to distill out 20 g butanol. Filtration of the 
residue product gave 528 g of pale yellow dibutyltin-monobutyltin butyl 
ethylene thiomalate. Analysis by atomic absorption spectroscopy showed 
that the product contained 16.6% Sn. 
EXAMPLE XXIV 
Example XVIII was repeated using one mole of ethylene glycol 
transesterified derivative with two moles dibutyl thiomalate. The 
resulting product was reacted with one mole of the 1:1 molar reaction 
product of dibutyltin oxide with dibutyl thiomalate. The resulting product 
was reacted further with one-half mole dibutyltin bis-(mono methyl 
maleate) and with one-half mole of dibutyltin bis-(dibutyl thiomalate). 
The resulting product was a pale yellow viscous liquid which had the 
following approximate structure: 
##STR23## 
EXAMPLE XXV 
One mole ethylene glycol, 2.5 moles thiomalic acid, and 3.5 moles n-butanol 
were reacted under a reflux fitted with water trap. p-Toluenesulfonic acid 
3.5 g was used as esterification catalyst. The reaction gave 94 grams 
aqueous phase in the trap, 9 grams distillate on vacuum stripping with 
refractive index 1.4076 (butanol RI = 1.3993 and ethylene glycol = 1.4318) 
and 595 grams of product with the following properties: 
______________________________________ 
Density 25.degree. C 1.108 
Refractive Index 25.degree. C 
1.4714 
Gardner Viscosity 25.degree. C 
A-4 
Percent SH 13.28 
Molecular Refractivity 63.1 
(Calculated from density and R.sub.1) 
______________________________________ 
The infrared spectrum of this product showed a characteristic hydroxyl 
absorption band. 
Consistent with these properties, the product is designated butyl ethylene 
thiomalate for which calculated % SH is 13.25 and molecular refractivity 
is 58.8, and the formula assigned is 
##STR24## 
Three di-n-octyltin stabilizers (A,B,C) were prepared from this product by 
reacting the thiomalate with different proportions of di-n-octyltin oxide. 
In each instance, the thiomalate was warmed to 55.degree. C, di-n-octyltin 
oxide added with stirring during a half-hour period, and water aspirator 
vacuum applied while warming to 80.degree. C, then holding at 80.degree. C 
for 2 hours to complete the removal of by-product water. 
The resulting pale yellow liquid products were filtered with suction to 
remove very small traces of solid impurities introduced along with the 
di-n-octyltin oxide. Details are tabulated in Table V. 
TABLE V 
______________________________________ 
Example A B C 
______________________________________ 
Butylethylene 62.5 g 55 g 45 g 
thiomalate 
Di-n-octyltin 37.5 g 45 g 55 g 
oxide 
Yield of di-n- 
94 g 92 g 89 g 
octyltin salt 
% Sn (atomic 12.25 14.9 17.7 
absorption) 
%S (iodimetric) 
8.1 7.2 5.9 
Sulfur/tin 2.4 1.8 1.2 
molar ratio 
______________________________________ 
EXAMPLE XXVI 
a. Dibutyl thiomalate preparation: 
This ester was obtained in 96.7% yield by reaction of 6000 g thiomalic 
acid, 9000 g butanol, 166 ml benzene, and 66.6 g p-toluene sulfonic acid 
catalyst. Properties of the dibutyl thiomalate were as follows: 
______________________________________ 
Refractive Index 1.4570 
Density 1.015 
Viscosity (Gardner) less than A-5 
Percent SH 12.25, 12.34 
(Theoretical %SH = 12.6) 
Weight Yield 10.545 g 
Weight recovered butanol 
3040 g 
______________________________________ 
b. Transesterification: 
Two moles dibutyl thiomalate, 1 mole ethylene glycol, and 3 g tetrabutyl 
titanate catalyst were stirred and heated for 3 hours at 125.degree. C. 
Vacuum was then applied, and volatiles stripped off to 135.degree. C and 
18 mm, to give butyl ethylene thiomalate having the following properties: 
______________________________________ 
Weight 503 g 
Refractive Index 
1.4632 
Density 1.063 
Viscosity (Gardner) 
A-4 
Percent SH 12.42 
______________________________________ 
Four monobutyltin stabilizers were prepared from this butylethylene 
thiomalate by reaction with 44% aqueous monobutyltin trichloride and 15% 
aqueous sodium hydroxide at 75.degree.-80.degree. C. The products were 
isolated by extraction of the milky reaction mixtures with cyclohexane, 
filtration, and evaporation of the extracts. Quantities of reagents used 
(on dry basis) and products obtained are shown in Table VI. 
TABLE VI 
______________________________________ 
A B C D 
______________________________________ 
Butylethylene 80g 72 g 72g 72g 
thiomalate 
Butyltin trichloride 
28.2 g 28.2 g 28.2 g 
28.2 g 
Sodium hydroxide 
12.0 g 12.0 g 11.4 g 
10.8 g 
Weight monobutyltin 
91g 80g 81g 81g 
butylethylene thiomalate 
% Sn (atomic absorption) 
12.0 g 12.9 g 12.8 g 
12.8 g 
% S (iodometric) 
9.6 g 9.5 9.5 9.4 
% Cl 0.2 0.3 0.6 1.1 
______________________________________ 
EXAMPLE XXVII 
Transesterifications of dibutyl thiomalate with ethylene glycol and various 
catalysts were run on a scale of about one mole (270 g of about 96% pure) 
dibutyl thiomalate, 0.5 mole (32 g) ethylene glycol, and catalyst under 
the conditions shown in Table VII below. 
TABLE VII 
______________________________________ 
Butyl 
Ethylene Thiomalate 
Time Final Yield R.I. % 
Catalyst g. Hrs. Temp .degree. C 
g. 25.degree. C. 
SH 
______________________________________ 
A Sodium Methoxide 0.7 
3 122 259 1.4580 
8.03 
B Butyl titanate 1.5 
4 135 268.5 1.4569 
12.3 
C Dibutyltin oxide 1.5 
4 165 252 1.4579 
12.2 
D p-Toluenesulfonic 
4 160 270 1.4582 
12.3 
acid 1.5 
______________________________________ 
Dibutyltin stabilizers were prepared from the above butyl ethylene 
thiomalates as follows: 
Dibutyl thiomalate 140 grams (93% assay) was warmed to 90.degree. C and 
dibutyltin oxide 125 grams was added slowly with stirring and continued 
heating. The dibutyltin oxide had dissolved by the time the mixture 
reached 130.degree. C to give dibutyltin mono (dibutyl thiomalate) a 
viscous liquid. 
A 50 g portion of each of the above preparations of butyl ethylene 
thiomalate was warmed to 125.degree. C, and 106 g of dibutyltin mono 
(dibutyl thiomalate) prepared as above was added with stirring, to give a 
homogeneous liquid product represented by the formula in Example XVIII. 
EXAMPLES XXVIII TO XXXIV 
Additional glycol alkyl thiomalates were prepared by direct esterification 
following the general procedure of Example XXV using 375 g (2.5 moles) 
thiomalic acid, except for increased catalyst use (6 g p-TSA) and 
temperature held to 125.degree. C maximum by adding hexane as needed. The 
reaction conditions and results are shown in Table VIII. The yield refers 
to stripped product, after heating under vacuum to 135.degree. C. 
TABLE VIII 
__________________________________________________________________________ 
Example No. 
Glycol grams 
Alcohol grams 
Yield g. 
%SH Theor. 
%SH Actual 
__________________________________________________________________________ 
XXVIII Neopentylglycol 
104 Isobutyl alcohol 
259 643 12.83 12.3 
XXIX Diethylene glycol 
106 Isoborneol 
539 879 9.39 9.0 
XXX Ethylene glycol 
62 n-Hexanol 357 737 11.19 10.4 
XXXI Ethylene glycol 
62 2-Ethylhexanol 
455 797 10.35 10.0 
XXXII Cyclohexane- 
144 n-Propyl alcohol 
210 627 13.16 12.5 
dimethanol-1,4 
XXXIII Ethylene glycol 
93 2-Phenylethanol 
305 674 12.24 11.9 
XXXIV Propylene glycol 
114 n-Dodecyl alcohol 
465 857 9.63 9.1 
__________________________________________________________________________ 
The odor characteristics of representative organotin thiomalate esters in 
accordance with the invention were evaluated by the following tests: 
TEST A 
A mixture of 200 g polyvinyl chloride homopolymer and 5 g of the organotin 
thiomalate ester being tested was blended five times for 20 seconds in an 
Osterizer high speed mixer, with 10 second rest intervals. The resulting 
blend was placed in a glass jar fitted with a metal screw cap, and heated 
for 30 minutes in an air circulating oven at 150.degree. C., the closed 
glass jar was then allowed to cool to room temperature and sniff-tested 
the next day. 
The organotin thiomalate esters set forth below were tested in this manner, 
and were found to give essentially odorless blends: 
EQU Example XVI; Dibutyltin bis-(butyl ethylene thiomalate) 
EQU Example I; Dimethyltin bis-(butyl ethylene thiomalate) 
The following organotin compounds not of the invention gave blends with an 
odor considered characteristic of isooctyl thioglycolate: 
Commercial Butyltin stabilizer, dibutylin bis(isooctyl thioglycolate) 
Commercial Octyltin stabilizer, di-n-octyltin bis(isooctyl thioglycolate) 
Commercial low odor organotin stabilizer of unknown constitution 
The superiority of the organotin thiomalate esters of the invention is 
evident from the results of this test, which measures the tendency of the 
plastic to release odors during compounding and processing. 
TEST B 
A mixture of 100 g polyvinyl chloride homopolymer, 2 g acrylic process aid, 
0.5 g Wax E lubricant and 3 g of the organotin stabilizer being tested was 
fluxed on a two role mill at about 330.degree. F for five minutes and 
sheeted off. The sheet was cut into strips measuring about 21/2 by 1 
inches and the maximum possible quantity of these strips (65 or more of 
plastic) placed in an 8 oz. glass jar fitted with a metal screw cap. The 
closed jars were kept in an air circulating oven at 60.degree. C for 60 
days, allowed to cool to room temperature and sniffed the next day. 
The following organotin thiomalate esters were tested in this way and found 
to give odorless plastics. 
EQU Example IX; Di-n-octyltin butylethylene thiomalate 
EQU Example X; Di-n-octyltin butylethylene thiomalate 
EQU Example XI; Di-n-octyltin butylethylene thiomalate 
EQU Example XII; Di-n-octyltin butylpropylene thiomalate 
EQU Example XIII; Di-n-octyltin butyl 1,4-butylene thiomalate 
The following organotin compound not of the invention in this test gave a 
plastic with a recognizable mercaptoester odor: 
Commercial octyltin stabilizer, di-n-octyltin di-(isooctyl thioglycolate). 
The superiority of organotin alkyl glycol thiomalate esters of the 
invention with different kinds and proportions of glycol is evident from 
the results of this test, which measures the tendency of the plastic to 
release odors during storage and use. 
The organotin thiomalate ester halides of the invention can be used as 
stabilizers with any polyvinyl chloride resin. The term "polyvinyl 
chloride" as used herein is inclusive of any polymer formed at least in 
part of the recurring group 
##STR25## 
and having a chlorine content in excess of 40%. In this group, the X 
groups can each be either hydrogen or chlorine. In polyvinyl chloride 
homopolymers, each of the X groups is hydrogen. Thus, the term includes 
not only polyvinyl chloride homopolymers but also afterchlorinated 
polyvinyl chlorides such as those disclosed in British Pat. No. 893,288 
and also copolymers of vinyl chloride in a major proportion and other 
copolymerizable monomers in a minor proportion, such as copolymers of 
vinyl chloride and vinyl acetate, copolymers of vinyl chloride with maleic 
or fumaric acids or esters, and copolymers of vinyl chloride with styrene, 
propylene, and ethylene. The invention also is applicable to mixtures of 
polyvinyl chloride in a major proportion with other synthetic resins such 
as chlorinated polyethylene or a copolymer of acrylonitrile, butadiene and 
styrene. Among the polyvinyl chlorides which can be stabilized are the 
uniaxially-stretch oriented polyvinyl chlorides described in U.S. Pat. No. 
2,984,593 to Isaksem et al, that is, syndiotactic polyvinyl chloride, as 
well as atactic and isotactic polyvinyl chlorides. 
The organotin mercaptodicarboxylate esters of this invention, both with and 
without supplementary stabilizers, are excellent stabilizers for both 
plasticized and unplasticized polyvinyl chloride resins. When plasticizers 
are to be employed, they may be incorporated into the polyvinyl chloride 
resins in accordance with conventional means. The conventional 
plasticizers 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. 
Particularly useful plasticizers are the epoxy higher fatty acid 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 
of the molecule, which is 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 monohydric 
alcohols 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 sorbitol. 
Glycerol is preferred. These 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 cottonseed oil, 
epoxidized tall oil fatty acid esters, epoxidized linseed oil and 
epoxidized tallow. Of these, epoxidized soybean oil is preferred. 
The 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. 
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 salts having 12 to 24 carbon atoms, such as stearic 
acid, lauric acid, palmitic acid and myristic acid, lithium stearate and 
calcium palmitate, mineral lubricating oils, 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 10%. Examples of such impact modifiers include chlorinated 
polyethylene, ABS polymers, and polyacrylate butadiene graft copolymers. 
The organotin thiomalate esters of the invention are employed in an amount 
sufficient to impart the desired resistance to heat deterioration at 
working temperatures of 350.degree. F and above. The longer the time and 
the more rigorous the conditions to which the resin will be subjected 
during working and mixing, the greater will be the amount required. 
Generally, as little as 0.25% total of the organotin thiomalate ester by 
weight of the resin will improve resistance to heat deterioration. There 
is no critical upper limit on the amount, but amounts above about 10% by 
weight of the resin do not give an increase in stabilizing effectiveness 
that is commensurate with the additional amount employed. Preferably, the 
amount is from about 0.5 to about 5% by weight of the resin. 
The organotin thiomalate esters of the invention are extremely effective 
when used alone, but they can be employed together with other polyvinyl 
chloride resin stabilizers, including non-mercaptide organotin compounds, 
particularly organotin maleate half-esters, if special efforts are 
desired. The organotin thiomalate esters of the invention in this event 
will be the major stabilizer, and the additional stabilizer will 
supplement the stabilizing action of the former, the amount of the 
organotin thiomalate ester being within the range from about 0.25 to about 
10 parts by weight per 100 parts of the resin, and the additional 
stabilizer being in the amount of from about 0.05 to about 10 parts of the 
resin. 
Among the additional metallic stabilizers are included polyvalent metal 
salts of medium and of high molecular weight fatty acids and phenols, with 
metals such as calcium, tin, barium, zinc, magnesium, and strontium. The 
non-metallic stabilizers include phosphites, epoxy compounds, phenolic 
antioxidants, polyhydric alcohols, and the like. Epoxy compounds are 
especially useful, and typical compounds are described in U.S. Pat. No. 
2,997,454. 
The stabilizer compositions of this invention can be formulated for 
marketing by mixing the organotin thiomalate ester with an inert diluent 
or with any liquid lubricant or plasticizer in suitable concentrations, 
ready to be added to the resin composition to give an appropriate 
stabilizer and lubricant or plasticizer concentration in the resin. Other 
stabilizers and stabilizer adjuncts can be incorporated as well. 
The preparation of the polyvinyl chloride resin composition is easily 
accomplished by conventional procedures. The selected stabilizer 
composition is formed, as described above, and then is blended with the 
polyvinyl chloride resins, or alternatively, the components are blended 
individually in the resin, using, for instance, a two or three roll mill, 
at a temperature at which the mix is fluid and thorough blending 
facilitated, milling the resin composition including any plasticizer at 
from 250.degree. to 375.degree. F for a time sufficient to form a 
homogeneous mass, five minutes, usually. After the mass is uniform, it is 
sheeted off in the usual way. 
For the commercial processing of rigid polyvinyl chloride, the stabilizer 
composition is conveniently mixed with all or a portion of the polymer to 
be stabilized with vigorous agitation, under such conditions to time and 
temperature that the stabilizer is sufficiently imbibed by the polymer to 
produce a dry, free-flowing powder. The well-known Henschel mixer is well 
suited to this procedure. 
The following Examples in the opinion of the inventor represent preferred 
embodiments of polyvinyl chloride resin compositions incorporating 
organotin thiodicarboxylic acid esters in accordance with the invention as 
stabilizers therefor. 
EXAMPLES 1 to 3 
The effectiveness as stabilizers for polyvinyl chloride resins of a number 
of organotin thiomalate esters in accordance with the invention was 
evaluated using a 205.degree. C (400.degree. F) oven heat stability test. 
The polyvinyl chloride resin test formulation employed was as follows: 
______________________________________ 
Component Parts By Weight 
______________________________________ 
Vinyl chloride homopolymer (Diamond 40) 
100 
Acrylic impact modifier (Kureha BTA-3) 
10 
Acrylic processing aid (Acryloid K-120N) 
3 
Lubricant (Wax E) 0.3 
Stabilizer 2 
______________________________________ 
The composition was milled on a two-roll mill at approximately 375.degree. 
F. After three minutes of mixing, the composition was sheeted off, and the 
sheets cut into strips, which were then placed in an oven heated at 
205.degree. C, and held there for up to 2 hours, or less, if the strips 
turned black before this time. Samples were removed from the strips and 
affixed to cards at 5-minute intervals, to evaluate the progressive 
heat-deterioration of the resin. 
The following organotin thiomalate esters were subjected to this test: 
a. dimethyltin (butyl ethylene thiomalate) of Example I, Run No. 1. 
b. dibutyltin (butyl ethylene thiomalate) of Example I, Run No. 4. 
c. dimethyltin (butyl neopentylene thiomalate) of Example XV. 
The degree of heat degradation was evaluated by the amount of color formed, 
that is, the extent of discoloration, relative to Control A, a test 
formulation containing dimethyltin bis-(isooctyl thioglycolate) (18.9% 
tin), and Control B, dimethyltin bis (di-n-butyl thiomalate). 
The scale used to characterize the amount of color formation is set forth 
below as Table IX. The scale covers the color range from colorless through 
yellow and orange to reddish brown, and ranges numerically from 
0-colorless to 9-brown-black, as follows: 
TABLE IX 
______________________________________ 
0 Clear and colorless 
1 Touch of yellow 
2 Very pale yellow 
3 Pale yellow 
4 Yellow 
5 Yellow-brown edges 
6 Light orange brown 
7 Orange brown 
8 Reddish brown 
9 Brown-black 
______________________________________ 
The appearance of the samples evaluated in accordance with this test is set 
forth in Table X. 
TABLE X 
______________________________________ 
Minutes 
400.degree. F 
Ex. 1 Ex. 2 Ex. 3 Control A 
Control B 
______________________________________ 
0 0 0 0 0 0 
5 0 0 0 0 0 
10 0 0 0 1 1 
15 1 0 1 4 4 
20 4 3 3 6 6 
25 6 4 7 8 9 
30 9 7 9 9 9 
35 9 9 9 9 9 
______________________________________ 
During the milling of the samples a strong mercaptoester odor was produced 
from Control A and a hydrogen sulfide odor from Control B, but no sulfur 
compound odor was noted from Examples 1, 2, and 3. The heat stability of 
Examples 1, 2, and 3 is clearly superior to Controls A and B. 
EXAMPLES 4 to 6 
In these examples, a stabilizer of the invention, dibutyltinmonobutyltin 
ethylene thiomalate of Example XXIII, was compared to dibutyltin bis 
(isooctylthioglycolate) at three stabilizer use levels, as indicated in 
Table XI in parts per 100 parts of resin, in the following: 
______________________________________ 
Test formulation: Parts by Weight 
______________________________________ 
Vinyl chloride homopolymer (Diamond 40) 
100 
Acrylic impact modifier (Kureha BTA-3) 
10 
Lubricants: 
Wax E montan wax ester 0.5 
Glycerol monostearate 0.5 
AC 629 (low molecular weight polyethylene) 
0.2 
______________________________________ 
The compositions were milled on a two-roll mill at about 375.degree. F. 
After three minutes of mixing, the compositions were sheeted off, and the 
sheets cut into strips, which were placed in an oven heated at 375.degree. 
F and at 400.degree. F. The following results were obtained: 
TABLE XI 
__________________________________________________________________________ 
375.degree. F 
Example 4 
Example 5 
Example 6 
Dibutyltin bis (isooctyl thioglycolate) 
Minutes 
0.3 part 
0.75 part 
1.5 parts 
0.3 part 
0.75 part 
1.5 parts 
__________________________________________________________________________ 
0 0 0 0 0 0 0 
5 0 0 0 2 1 0 
10 1 0 0 4 1 0 
15 3 0 0 5 2 1 
20 6 1 0 8 3 1 
25 7 1 0 8 4 2 
30 7 2 0 8 4 2 
35 7 3 1 8 5 3 
40 7 4 1 8 5 3 
__________________________________________________________________________ 
400.degree. F 
Example 4 
Example 5 
Example 6 
Dibutyltin bis (isooctyl thioglycolate) 
(Minutes) 
0.3 part 
0.75 part 
1.5 part 
0.3 part 
0.75 part 
1.5 parts 
__________________________________________________________________________ 
0 0 0 0 0 0 0 
5 2 0 0 4 2 1 
10 7 1 1 8 3 2 
15 8 3 1 9 5 3 
20 9 5 2 9 8 4 
25 9 8 3 -- 9 5 
30 -- 9 4 -- -- 8 
__________________________________________________________________________ 
The test results show that the 16.6% tin content stabilizer of this 
invention is remarkably superior to the 18.0% tin content stabilizer that 
has long been considered the standard of the industry. In spite of the 
lower tin content, 0.75 part of the stabilizer in Example 5 gives better 
stabilization than 1.5 parts of dibutyltin bis-(isooctyl thioglycolate). 
In addition, the samples of Examples 4, 5, and 6 were free of the 
objectionable mercaptoester odor that characterized the samples containing 
dibutyltin bis-(isooctyl thioglycolate). 
EXAMPLES 7 to 10 
Formulations were prepared employing the reaction products of dibutyltin 
mono (dibutyltiomalate) and butyl ethylene thiomalate of Examples XXVII A, 
B, C, and D in the following formulation. 
______________________________________ 
Parts by 
Formulation: weight 
______________________________________ 
Polyvinyl chloride homopolymer (Borden VC-95) 
100 
Acrylic impact modifier 10 
Acrylic process aid 3 
Wax E lubricant 0.3 
Stabilizer 2.0 
______________________________________ 
The formulations were milled, on a two-roll mill at about 375.degree. F. 
After 3 minutes of mixing, the compositions were sheeted off, and the 
sheets cut into strips, which were placed in an oven heated at 400.degree. 
F. The following results were obtained: 
TABLE XII 
__________________________________________________________________________ 
400.degree. F 
Example 7 
Example 8 
Example 9 
Example 10 
Minutes 
(Ex XXVIIA) 
(Ex XXVIIB) 
(Ex XXVIIC) 
(Ex XXVIID) 
__________________________________________________________________________ 
0 0 0 0 0 
5 0 0 0 0 
10 0 0 0 0 
15 3 1 3 1 
20 6 1 6 4 
25 8 6 8 7 
__________________________________________________________________________ 
All samples provided good early color control, and acceptable long term 
heat stability. 
EXAMPLE 11 
In this example, the butyltin butylethylene thiomalate product of Example 
III was compared to the dibutyltin thiomalic acid of Weinberg U.S. Pat. 
No. 2,832,752 in the following formulation: 
______________________________________ 
Parts by Weight 
______________________________________ 
Polyvinyl chloride homopolymer (Diamond 40) 
100 
Calcium stearate (lubricant) 
1 
Acrylic process aid 2 
Stabilizer 2.0 
______________________________________ 
The formulations were milled, on a two-roll mill at about 375.degree. F. 
After 3 minutes of mixing, the compositions were sheeted off, and the 
sheets cut into strips, which were placed in ovens heated at 375.degree. F 
and at 400.degree. F. The following results were obtained: 
TABLE XIII 
__________________________________________________________________________ 
Oven test 375.degree. F. 
Oven test 400.degree. F. 
Dibutyltin bis Dibutyltin bis 
Example 11 
(thiomalic acid) 
Example 11 
(thiomalic acid) 
Minutes 
15.8% Sn 
18.9% Sn 15.8% Sn 
18.9% Sn 
__________________________________________________________________________ 
0 0 0 0 0 
5 0 0 0 1 
10 0 1 0 3 
15 0 2 1 5 
20 1 2 2 6 
25 1 3 7 7 
30 1 3 9 9 
35 1 4 -- -- 
40 1 4 -- -- 
__________________________________________________________________________ 
Clearly the product of Example 11 provides superior stabilization in spite 
of a lower tin content. 
EXAMPLES 12 to 17 
The Di -n-octyltin derivatives of butyl glycol thiomalates of Examples X, 
XII, XIII, XXVA, XXVB, and XXVC were compared in the following resin 
formulation: 
______________________________________ 
Parts by Weight 
Diamond 40 polyvinyl chloride homopolymer 
100 
Acrylic impact modifier 10 
Acrylic process aid 2 
Glycerlymonoricinoleate lubricant 
0.5 
Stabilizer 1.5 
______________________________________ 
The formulations were milled, on a two-roll mill at about 375.degree. F. 
After 3 minutes of mixing, the compositions were sheeted off, and the 
sheets cut into strips, which were placed in an oven heated at 375.degree. 
F and at 400.degree. F. The following results were obtained: 
TABLE XIV 
__________________________________________________________________________ 
Control 
Di-n-octyltinbis 
400.degree. F 
(isooctylthiogly- 
Example 12 
Example 13 
Example 14 
Example 15 
Example 16 
Example 17 
Minutes 
colate) Ex. X Ex. XII Ex. XIII 
Ex. XXVA 
Ex. XXVB 
Ex. 
__________________________________________________________________________ 
XXVC 
0 0 0 0 0 0 0 0 
5 1 0 0 0 1 0 1 
10 3 2 3 3 3 2 2 
15 4 4 4 4 4 4 3 
20 5 6 6 6 5 5 5 
25 9 9 8 9 8 8 6 
30 -- -- 9 -- 8 9 8 
35 -- 9 -- 
__________________________________________________________________________ 
The dioctyl tin bis-(isooctyl thioglycolate) exhibited a pronounced 
mercaptoester odor while being milled and also on subsequent aging of 65 g 
plastic in an 8 oz. jar at 60.degree. C, while the other samples of 
Examples 12 to 17 were free or odor. The stabilizers of Examples 12 to 17 
all have lower tin contents, but provide either equivalent or better heat 
stability than the dioctyltin bis-(isooctyl thioglycolate). 
______________________________________ 
Parts by Weight 
______________________________________ 
Diamond 40 polyvinyl chloride homopolymer 
100 
Acrylic impact modifier 10 
Acrylic process aid 3 
Wax E lubricant 0.3 
Stabilizer 2.0 
______________________________________ 
TABLE XV 
______________________________________ 
Dioctyltin 
400.degree. F 
bis iso- 
Min- octyl thio- 
Example 15 Example 16 
Example 17 
utes glycolate Ex. XXV A Ex. XXV B 
Ex. XXV C 
______________________________________ 
0 0 0 0 0 
5 1 1 0 1 
10 3 3 2 2 
15 4 4 4 3 
20 5 5 5 5 
25 9 8 8 6 
30 -- 8 9 8 
35 -- 9 -- -- 
______________________________________ 
EXAMPLES 18 to 20 
The di-n-octyltin butyl glycol thiomalates of Examples IX, X and XI were 
compared in the following formulation: 
______________________________________ 
Parts by Weight 
______________________________________ 
Diamond 40 polyvinyl chloride homopolymer 
100 
Acrylic impact modifier 10 
Acrylic process aid 2 
Glycerylmonoricinoleate 0.5 
Stabilizer 1.5 
______________________________________ 
The compositions were milled on a two-roll mill at about 375.degree. F. 
After three minutes of mixing, the compositions were sheeted off and the 
sheets cut into strips, which were placed in an oven heated at 400.degree. 
F. The following results were obtained: 
TABLE XVI 
______________________________________ 
400.degree. F 
Ex. 18 Ex. 19 Ex. 20 
Di-n-octyltin bis 
Minutes Ex. IX Ex. X Ex. XI 
(isooctyl thioglycolate) 
______________________________________ 
0 0 0 0 0 
5 0 0 0 1 
10 2 2 2 3 
15 3 4 4 4 
20 5 6 5 6 
25 9 9 8 8 
30 -- -- 9 9 
______________________________________ 
The samples of Examples 18 to 20 had at least equal heat stability to 
di-n-octyltin bis (isooctyl thioglycolate) in spite of a lower tin 
content, and also were far superior in oder quality while milling and on 
aging of milled plastic in jars at 60.degree. C. 
EXAMPLES 21 to 25 
The dibutyltin butyl ethylene thiomalate of Example XVI was blended with 
various quantities of mixed dibutyltin-monobutyltin ethylene thiomalate of 
Example III, to study the effect of the monobutyltin component in the 
following resin formulation. 
______________________________________ 
Parts by Weight 
______________________________________ 
Diamond 40 polyvinyl chloride homopolymer 
100 
Acrylic impact modifier 10 
Acrylic process aid 3 
Wax E lubricant 0.3 
______________________________________ 
The compositions were milled on a two-roll mill at about 375.degree. F. 
After 3 minutes of mixing, the compositions were sheeted off and the 
sheets cut into strips, which were placed in an oven heated at 400.degree. 
F. The following results were obtained: 
TABLE XVII 
__________________________________________________________________________ 
Example 22 
Example 23 
Example 24 
Example 25 
400.degree. F 
Example 21 
Ex. XVI 1.85 
Ex. XVI, 1.7 
Ex. XVI, 1.2 
Ex. XVI, 1.2 
Dibutyltin bis 
Minutes 
Ex. XVI, 2.0 
Ex. III 0.15 
Ex. III, 0.3 
Ex. III, 0.8 
Ex. III, 0.8 
isooctyl 
__________________________________________________________________________ 
thioglycolate 
0 0 0 0 0 0 0 
5 0 0 0 0 0 1 
10 0 0 0 0 1 1 
15 1 1 1 1 1 2 
20 2 2 2 2 3 3 
25 3 3 3 4 4 4 
30 6 6 6 8 8 8 
35 8 8 8 8 8 9 
__________________________________________________________________________ 
All samples stabilized with stabilizers of this invention had better 
initial color control than the dibutyltin bis isooctyl thioglycolate, 
whether or not a monobutyltin component was present. All formulations 
containing Examples 21 to 25 were free of mercaptoester odor, while 
dibutyltin bis isooctyl thioglycolate gave off a noticeable mercaptoester 
odor during processing, and on subsequent storage in a closed container. 
EXAMPLE 26 
In this example, the dibytyltin butyl ethylene thiomalate of Example XVI 
was tested in a flexible plasticized polyvinyl chloride homopolymer 
composition. 
______________________________________ 
Formulation: Parts by Weight 
______________________________________ 
Geon 103 EP polyvinyl chloride homopolymer 
100 
Dioctyl phthalate 37 
Stabilizer 1 
______________________________________ 
The compositions were milled on a two-roll mill at about 375.degree. F. 
After 3 minutes of mixing, the compositions were sheeted off and the 
sheets cut into strips, which were placed in an oven heated at 375.degree. 
F. The following results were obtained: 
TABLE XVIII 
______________________________________ 
Example 26 Dibutyltin bis 
375.degree. F 
Example XVI isooctyl thioglycolate 
Minutes (16.2% Sn) (18% Sn) 
______________________________________ 
0 Colorless Colorless 
15 Colorless Very pale yellow 
30 Colorless Very pale yellow 
45 Very pale yellow 
Pale yellow 
60 Yellow Yellow 
75 Yellow Yellow 
90 Yellow Yellow 
105 Amber Brown 
120 Orange Brown 
______________________________________ 
At 350.degree. F, both samples remained colorless for 2 hours. The Example 
26 samples were free of mercaptoester odor, while the dibutyltin bis 
isooctyl thioglycolate samples had a pronounced odor during as well as 
after processing. 
EXAMPLE 27 
In this Example, rigid PVC was stabilized with di-n-octyltin butyl 
propylene thiomalate (see Example XII for preparation) above and used 
together with certain conventional PVC stabilizers. 
______________________________________ 
Formulation: Parts by Weight 
______________________________________ 
Vinyl chloride - ethylene 100 
copolymer (chlorine content 
54.8% intrinsic viscosity 
0.55 deciliters per gram 
measured in cyclohexanone 
at 30.degree. C) 
Acrylic impact modifier 10 
Acrylic process aid 3 
Glycerol monostearate 0.4 
lubricant 
______________________________________ 
Sam- Sam- Sam- 
Stabilizers: ple A ple B ple C 
Zinc stearate 0.4 0.4 -- 
Calcium benzoate 0.3 0.3 -- 
2,6-di-t-butyl-p-cresol 
0.05 0.05 -- 
Epoxidized soybean oil 
0.5 0.5 -- 
Di-n-octyltin butyl propylene 
none 0.5 1.0 
thiomalate (Example XII) 
______________________________________ 
RESULTS: 
a)Oven Test 350.degree. F. 
Minutes Sample A Sample B Sample C 
0 0 0 0 
15 0 0 0 
30 1 0 0 
45 4 0 0 
60 9 1 0 
75 -- 1 1 
90 -- 3 1 
105 -- 6 2 
120 -- 9 2 
b) Oven Test 375.degree. F. 
Minutes Sample A Sample B Sample C 
0 0 0 0 
5 2 0 0 
10 6 1 0 
15 9 1 0 
20 -- 3 1 
25 -- 6 1 
30 -- 9 1 
35 -- -- 2 
40 -- -- 3 
______________________________________ 
The results show excellent stabilization by the di-n-octyltin stabilizer of 
this invention and significant improvement when added to the conventional 
calcium-zinc combination. The absence of mercaptoester odor makes 
economical combinations represented by Sample B practical for clear 
plastic intended for packaging applications such as bottles.