DE1801274A1 - Stabilized vinyl halide polymer compositions and processes for stabilizing organotin mercaptocarboxylic acid esters - Google Patents

Description

DR. ELISABETH JUNG. DR. VOLKER VOSSIUS, DIPL.-ING. GERHARD COLDEWEY

PATENTANWÄLTE fOU IZ / A

β MDNCHEN23 · SIEGESSTRASSE 26 · TELEFON 348067 ■ TEt-EGRAMM-ADDRESS E: IN VE NT / M DNCH EN

u.Z .; D 766 (Vo / kä)

.4. Oct. 1968 Oaae 2135ο06 - NU

TENNECO OHEMICALSc INCi, New York, N ₀ Y ₀ , VoSt ₀ A ₀

"Stabilized vinyl halide polymer compositions and processes " to stabilize organotin mercaptocarboxylic acid esters "

Priority? 5 »October 196 ?, VOSt, A. _? Registration number 6? 3 00?

Organotin meroaptocarbonsäureester ,, d "h, the Kondensationspro""by-products Mercaptoaarbonsäureestern with organotin or -oxyden-, excellent stabilizers for vinyl halide Polyraermasseno are The preparation of these compounds and their use as stabilizers are in the United States ₀ -" patents 2,641,588 , 2 64-1 596 and 2 648 650. Their use as stabilizers for vinyl halide polymer masses is, however, limited to a considerable extent by their instability ο even after standing for one day at room temperature, the organotin mercaptocarboxylic acid esters are subject to decomposition

I ^ with the formation of crystalline thioglycolic acid esters and others

τ compounds ,, which are unsuitable as stabilizers * Es wur ~

^m the beraits different substances as Konservierungemittel or Stabiliaatoren for organotin mercaptocarbonsäureeeter before =

geschlagens but is not completely satisfactory for this purpose Sun Z ₉ B, su inhibited ₀ weak by the addition of polyvalent metal salts carboxylic acids, such as calcium ~ 2 ~ äthylh8xoät or zinc · "naphthenate an organotin mercaptocarboxylic acid esters its decomposition on standing? however, this has an adverse effect on its ability to stabilize vinyl halide = polymeric <>

The object of the invention is it _? To provide connections? which, after addition to organosense aereaptocarboxylic acid esters, result in products or product mixtures which have a considerably lower tendency to decompose when standing and. which are at least as effective stabilizers for vinyl halogens * = · nid ~ polymer compositions, as are the untreated organotin mer = · captocarboxylic acid esters »- ...

The invention is thus a stabilized vinyl halide ~ polymer composition _f containing a VinyXhalogenid ^ polymer and about 1 to 10 wt _o = parts per 100 Gev. parts of the vinyl halides polymer of a stabilizer containing _P of su about 60 to 90 percent "= $ from a Organosense ^ raercaptoearboxylic acid esters of the general formula I.

^R n ^Sn Vn. W.

in which H is an alkyl = ,. Oxyalkyl- _s aryl- =, oxyaryl = or cycloalkyl radical and X is de ^ / mercaptocarboxylic acid with 2 to 6 carbon atoms, the sulfur atom of which is bonded to the tin atom, and η is an integer with a fourth from 1 to 3 ,, and about 5 to 40 weight _c - $ a Organoziimcarboxylats of the general formula II '

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R '_OC - R "

(II)

R »

in which R 'is an alkyl radical with 4 to 8 carbon atoms, R "an alkyl radical with 8 to 17 carbon atoms» an alkenyl radical with 8 to 17 carbon atoms or the radical -CHsCH-C-OR ¹ "is and R ³ "is an alkyl radical with 1 to 18 carbon atoms, an eyeloaliphatic radical? an alkenyl radical with 2 to 18 carbon atoms or an aralkyl radical"

Beispiele-, .for organotin mercaptoearbonsäureester, the OF INVENTION ~ dung can be stabilized according tentschriften _f are in the USAO-Pa '2,641,588, described 2,641,596 and 2,648,650, these compounds have the above-indicated general formula I in which R _f X and η have the meaning given ,, Specific examples of these compounds are monobutyltin tris ~ (cyclohexylthioglycolate} , dihexylssinn-bis-ihexjrlthiopropionate) -, triphenyltin butylthiovalerate and tricyclo «= · hexylainn ^ benzylthiocaproate. Particularly suitable Grganozinn = · _r mercaptocarboxylic acid esters which erfindungSi = emäss be stabilized by adding a Organozinncarboxylats "are the alkyltin Thioglycolates the general formula III

R " _n Sn (SCHj ₃ COOR ² ) ^ _n (III)

in which R * is an Aikylrest with 4 to 8 carbon atoms and R one Alkyl- ■ aryl- = ,, aralkyl-, alkaryl- or cycloalkylreat means · = tet and η is an integer with a value from 1 to 3, ST) esieJle examples for these compounds are dibutyltin = ---

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BATH

c = * JQL txn

{butylthioglycolate) "Tributylsinn ^ iseoctylthioglykolat ₉ Octylssinn = tris ~ (benzylthioglycolate) and dibutyl3inn" to ~ (cyelo ~ hexylthioglycolate) *

Specific examples of the erfindungsgeinäss as stabilizers for the organotin ^ mereaptocarbonsäureester used Organo = tin carboxylates of the general formula II are dibutyltin "pelargonate, dibutyl tin dilaurate" Dibutylzinndiateara.t, Dihexyliiinndisleat ,, Dioctylzinnditallat, dibutyltin Dioctylzinndiundecylenat _t = "up to ~ (neodecanoate) ρ dioctyltin bis -Cneotridecanoate} dibutyltin = bia- (monomethyl maleate) _t dihexyltin ~ bi8- (monohexyl maleate) _t dihexyltin-bis-monoisooctyl maleate) _t dibutyltin-bis- (monocetyl maleate) _f dibutyltin-bis-butylzooctadeeyl maleate = (butylzooctadeeyl) = monoallyl maleate}, dibutyl tin bis (monohexinyl maleate), dibutyl tin bia-Cmeno ^ ethoxyethyl maleate), dioctyl tin ^ and caonocyclohexyl maleate. Dihexyltin- = bis- (mpnobenzyl "= maleate} ₉ Butylhexylziim-bis-iraeno ^ terto-butylbenEylmaleat) And Butylhexylzinn ^ bis-imon & ^ - hydroxymethyl-S ^ norbonylmaleate and mixtures thereof »

The organotin carboxylates of general formula II can be prepared by conventional methods, _a B z _e by reacting a Dialkyljzinnoxyds with the corresponding monocarboxylic acid or by reaction of a dialkyltin dichlorides with the alkali metal salt of Monocarbonsäureί:

*.

"In most cases contain erfindungsgemäes taping for stability"'the Stabilisaj used vinyl halide polymer compositions tors about 60 to 95 percent of the $ _s ~ Organoginn-mercaptocarboxylic -

j esters of the general formula I and 5 to 40 wt, = ^ of the organo-

tin carboxylate of the general formula H ₀ Particularly favorable

Results are obtained with stabilizers 80 to 90 wt _o ~ # of organotin mercaptocarbonsäureesters and 10 to 20 wt »- # of 0rganozinncarboxylat3 given by

The stabilizers to be used according to the invention can be produced by adding to the organotin mercaptocarboxylic acid ester of the general formula I such an amount of the organotin carboxylate of the general formula II that is sufficient to inhibit the decomposition of the organotin mercaptocarboxylic acid ester and that there is a tendency to Precipitation of crystalline decomposition products limited to a minimum. In most cases, about 5 to 70 parts by weight of organotin be "carboxylate per 100 weight, parts by the organotin mercaptocarbonsäureesters used" The best results are obtained with the addition of 10 to 25 percent "," = parts Örganozinncarboxylat 100 percent _e - Tei = len organotin mercaptocarboxylic acid esters obtained "Liquid organotin carboxylates are the organotin mercaptocarbon" säureester _s mixed at room temperature while solid organotin carboxylates such as dibutyltin distearate are generally first mixed at room temperature with the-mercaptocarboxylic organotin and the mixture to temperatures of from about 61 to 82 ⁰ C is heated until a clear solution is obtained, and then the solution is cooled.

The present invention with the aforementioned stabilizers to be stabilized vinyl halide polymer compositions are the polymerisation * * _t obtained by polymerization of vinyl halides in the presence or absence of a copolymerizable monomer "The term" vinyl halide'Polymermassen "includes vinyl halide Hoiiiopolymerisate such as polyvinyl chloride and polyvinyl"

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bromide and vinyl halide ^ copolymers one as s ', B' by copolymerization of vinyl halides with vinyl acetate _f vinyl propionate "vinylidene chloride, styrene, methyl methacrylate" fumaric · "and maleates receive" As vinyl halide is usually country vorsugsweise uses the chloride However bromide and Pluorid can also be used "Examples of suitable copolymers are those products that are at least 70 $> vinyl halide Sinheiten and up to 30 $> other comonomer input = units included. According to the invention, polymer mixtures can also be stabilized which contain larger amounts of vinyl halide and lesser amounts of other synthetic resins, such as chlorinated polyethylene, polyacrylic acid and polymethacrylic acid esters and ternary copolymers of acrylonitrile, butadiene and styrene. Pelyiaerisat and the stabilizer, the polymer compositions, also plasticizers such as Dioetylphthalat _f Dlbutylsebasat, Srioresy phosphate and OctyldipL, -! ny phosphate ₉ lubricants, other heat = and Lichtstabilisatorenj as epoxidized oils and polyols, pigments, dyes, extenders, solvents and other cement resin additives contained in the usual amounts «

According to the invention, even a small amount of the stabilizers is sufficient for the vinyl halide ^ Polyjaermassen «. It was found that already 1 # of the stabilizer, based on. the weight of the polymer mass, causes a noticeable improvement in heat and light stability. About $ 10 or more of the stabilizer can be used, but these larger amounts generally do not provide any further improvement in property

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th of the polymer compositions s, and for this reason such high amounts are generally not used «. The amount of stabilizer used in each case, which develops the best stabilizing effect, depends, among other things, on the type of stabilizer and the vinyl halide polymer composition. In general, 2 to 6 % of the stabilizer are used based on the weight of the vinyl halide polymer composition.

The stabilized vinyl halide polymer compositions are generally prepared by mixing the stabilizer into the Vinylhaloge "nid-polymer composition on a roll mill at such a temperature the mixture is liquid _f in the" z "B" on a two roll mill at a temperature of 149-205 ⁰ C _? and sojlange _f is obtained until a homogeneous mixture. The plasticizer and other additives can be added together with the stabilizer. The stabilized polymer mass can then be drawn off from the roller mixer in the form of a film of the desired thickness, which is optionally treated _afterwards, for example, polished or grained.

The thermal stability of the stabilized polymer compositions is determined by DASB to specimens with dimensions of 25 "4 x 25 _f 4 mm, are cut from films _t hot in a 191 ⁰ C circulating air oven is, and takes samples periodically until the Ab = construction completely is what shows up by a color change _o

The examples illustrate the invention.Parts are based on weight,

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Example I.

A mixture of 2564 parts of Tliioglykolsäureisooctylester ^ prepared by esterification of thioglycolic acid with isooctanol ₉ was 1548 parts of dibutyltin oxide and 1560 parts of benzene is provided at reflux at 90 to 95 ⁰ O heated "to 109 parts of water are distilled off azeotropically. The reaction mixture is then heated to 90 ° C./37 to 58 torr to separate off the benzene. The residue is cooled and filtered Amount of a white, kriatal = linen precipitate has excreted "

Example 2

180 g freshly prepared dibutyltin bis (isooctylthioglycolate) according to example 1 are at room temperature with 20 g of dibutyltin = bis- (monoisooctylraaleate) mixed »The resulting mixture is a clear solution that remains clear even after several months of storage at room temperature.

example 3

180 g of Example freshly prepared Dlbutylzinn 1 = "up to ~ (isooctylthioglycolate) v / ground at room temperature with 20 g of diethylene = butyltin bis (neodecafleat) mixed" The resulting mixture is a clear solution _p which even after several months of storage at room temperature remains clear «

Example 4

180 g according to Example 1 freshly prepared dibutyltin bis " (isooctylthioglycoiate) v / ground at room temperature with 20 g of di-

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butyl single dipelargonate mixed. The mixture obtained is a clear solution that remains clear even after several months of storage at room temperature,

Example 5

A stabilized polyvinyl chloride polymer composition is as follows manufactured:

A mixture of 100 parts of polyvinyl chloride and 0.2 part of a lubricant wax is mixed with 2 parts of a stabilizer to be used according to the invention or a comparative stabilizer. The lubricant wax consists of equal parts of synthetic long-chain fatty acids, which are partially saponified with calcium, and a montan wax ester, which is also partially saponified with calcium optionally, the roll surface temperature is maintained at 171 ⁰ C _o the mixture for 5 minutes on the Walee ver = mixed and then ₁ 143 mm thick film detached in the form of a flexible and homogeneous ₉ Ij from the film, samples with dimensions of 25.4 x mm cut 25.4 and "in one ümwäleluftofen at 191 ⁰ C, where <> the samples are taken periodically from the oven until the reduction is complete, as evidenced by a color change. The results obtained are summarized in Table I:

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ίο

Ver
search Tatelle I.
stabilizer required time
in minutes to
Dismantling the samples
at 191 ⁰ C 5A
5B
5C Product of example 2
(90 # Bibutyltin-bis ° (isooetyl -
thioglycolate) and 10 f> dibutyl
tin-bis-monoisooctyl maleate))
Dibutyltin-bis- (ieooctylthio =
glycolate)
90 $> dibutyltin ~ to ~ (isooctyl-
thioglycolate) and 10 "J> zinc octoate 80
70
20th

Example 6

Stabilized polyvinyl chloride polymer compounds are given the following «= mass produced:

A mixture of 100 parts of polyvinyl chloride 15 parts of an acrylonitrile-butadiene-styrene terpolymer, 4 parts of polyacrylonitrile, 1.35 parts of glyceryl dimenericinoleate, 0.5 part of stearyl stearate and 0.001 part of a blue dye are mixed with 2 parts of a stabilizer to be used according to the invention and a comparison stabilizer offset "the components are mixed together first at room temperature, and = closing the mixture added to a steam-heated Zweiwalzenmiseher whose roll surface is maintained at 171 ⁰ C _e After 5 minutes of treatment on the roll, the product is in shape removed of a 1.143 mm thick _g flexible and homogeneous foil. The thermal stability of the product was determined according to Example 5. In. Table II summarizes the results obtained

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label II

Ver
search stabilizer required time
in minutes to
Dismantling the samples
at 191 ⁰ C ^ A
6B
6C
6D
6Έ Product of example 2
Product of example 3
Product of example 4
Dibutyltin ~ biB- (isooctyl-
thioglycolate)
90 # dibutyltin-bis- (ieo0ötyl ~
thioglycolate) and 10 # barium
nonylphenolate) 80
80
80
80
60

From Tables I and II it can be seen that the polymer compositions, the stabilizers of the invention (experiment Wr. 5A, 6a, OB and 6C), are at least as stable at 191 C as the polymer masses »which alone contain dibutylasinn-bis-isobctylthioglycolate) (Trials 5B and 6D) included. The polymer masses that which contain comparative stabilizers (experiment 5C and 6E) are considerably less stable than the polymer compositions that contain dibutyltin bis (isooctylthioglycolate) alone.

Example ?

It is prepared a series of stabilizers 90 $> Di ° butyltin = bi3 "(i80octylthioglykolat} and IO 56 of a dibutyl« * - tin carboxylate of the general formula II "If the dibutyl tin carboxylate is liquid * the components exploiting room temperature are mixed together . If the dibutyl tin carboxylate bsi room temperature is fixed, the mixtures are heated to 71 to 82 ^S C until a clear solution is obtained ₀ Thereafter, the mixtures are cooled and 5 days at room temperature

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"The results obtained are shown in Table III .. compiled:

Tabel : CII Appearance of a Ver used dibutyl sensory Physical 90:10 Wed search carboxylate Shape of di « schung von Di «=> butyltinear btttylssinn ~ to » boxylates (isooctylthio- » glycolate) and Dibutyl tin car- boxylat naoh 5 Days. At room · » temperature clear solution 7A Dibutyltin ~ bis- (mono ~ fluid propyl maleate) clear solution 7B Dibutyltin-bia ~ (mono = fluid isooctyl maleatej clear solution 7C Dibutyltin <= bis- (mono · » fluid isohexadecylmaieate} clear solution 7D Dibutyltin = »to ~ (monoce ty I =
maleate fixed clear solution 7B Dibutyltin-bia-'i mono- fluid ally lmaleate) clear solution 7F Dibutyltin-bis "- (mono-2- fluid ethoxyethyl maleate) clear solution 7G Dibutyltin = bis- (mono- fixed cyclöhexyl maleate} clear solution 7H Dibutyltin => b ± s ~ (niQnQ '~ fluid - hexinyl maleate clear solution 71 Dibutylinn "= to - = - (mono ~ 2 ~ fluid hydr oxymethyl-5 = » norbornyl maleate) clear solution 7Y Dibtttyltin ~ bi3- (mono- fluid benzyl maleate} clear solution 7K Dibutyltin bls- (neo <= fixed pentanoate) clear solution 71 Dibutyltin-bi8- (2 = fixed ethyl hexoate) clear solution 7M Dibutyltin distearate fixed The solution ent 7W none holds considerably che kengen one white, crystalline. precipitation

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After one month of storage at room temperature, the mixtures are 7A to TM still clear except for a few crystals at the bottom of the container »All mixtures are effective stabilizers for vinyl halide polymer compositions, and they maintain their activity as a stabilizer for a long time.

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Claims (1)

= »14 -
Ρ. _Ί at _M e η t aj B ₁₁ Jf ₁₁ Jr Ü c lijg 1 * Stabilized vinyl halide polymerase, containing © in vinyl halide polymer and about 1 to 10 parts by weight. Per 100 Ge * - ₉ weight parts by the Vinylfaalogenid-Polymer® eines'Stabilisators, the "u about 60 to 90 percent by _e - = j6 of a örganosinsirJBereaptoear-> acid esters of the general formula I X ^ _n (I) in which R is an alkyl · =, oxyalkyl = »aryl», oacyaryl-. . or Qyolo- Ksfcer · one
alkyl radical and X denotes the / mercaptocarboxylic acid with 2 to 6 carbon atoms; whose sulfur atom is bonded to the tin atom, and η is an integer having a value von.-l to 3, and about 5 to 40 percent of a _e -5o Organoainnoarboxylats of the general formula II q R »Λ) 0 -R" Sn R ¹ (II) consists in which R 'is an alkyl radical with 4 to 8 carbon atoms, R ^{M is} an alkyl radical with -8 to 17 carbon atoms, an alkenyl radical with 8 to 17 carbon atoms or the radical -CHs = CH = O-OR ¹¹³ means and R ' ^{ts is} an alkyl radical with 1 to 18 carbon atoms, a cycloaliphatic ^ Re & t, an alkenyl radical with 2 to 18 carbon atoms which is an aralkyl "radical" 2. Polymer composition according to claim 1, containing 2 to 6 wt »° ~ Parts of the stabilizer per 100 parts by weight of polyvinyl chloride. 3, polymer composition according to claim 2, containing a Stabili ~ aator from 80 to 90 wt _o "* SS a OrganoBinn ^ mercaptocarboxylic SC9819 / 1238 Acid ester of the general formula III. . n \ Sn (SCH ₂ COOR ² ) ^ _n (III) 1 '2 in which R is an alkyl radical with 4 to 8 _{carbon atoms s} R is an alkyl, aryl, aralkyl-s alkaryl or cycloalkyl radical and η is an integer with a value of 1 to 3, and 10 to 20 Grew » -96 of an organotin carboxylate of the general formula H ₀ 4 »Polymer composition according to claim 3i containing the organotin mercaptocarboxylic acid ester Dibutylsense isooctyl glycolate. 5 β polymer composition according to claim 4 »containing as organotin carboxylate Dibutyltin-bis- (mono-n-propyl maleate). 6. Polymer composition according to claim 4 »containing as Qrganotinncarboxylat dibutyltin = bis (monoisooctyl maleate) _e 7 «polymer composition according to claim 4, containing as organotin" carboxylate dibutyltin di pelargonate » 8, polymer race according to claim 4 »containing as organotin = carboxylate dibutyltin- = bis- (neodecanoate) o 9ο Stabilizer for vinyl halide »Po? .Ymermasssn _f containing about 60 to 95 fiew ^ jd of an organotin mercaptocarboxylic acid esters of the general formula I.
co öd R _n Sn X ₄ ^ _{n (x)} ^ω in which R is an alkyl · = ,. Oxyalkyl- _P Aryl-y Oxy aryl = · or Cyclo- ^ Ester one J ^ alkyl radical and λ der / mercaptocarboxylic acid with 2 to 6 O = atoms means "whose sulfur atom is bonded to the tin atom" and η is an integer with a value of 1 big 3 is _s and about 5 to 40 ßew _o ~ # of an organotin carboxylate of the general formula II ·· O Rl OC -R " Sn '(II) R »/ ^S OC -R" n in which R * is an alkyl radical with 4 to 8 carbon atoms and R "denotes an alkyl radical with 8 to 17 carbon atoms, an alkenyl radical with 8 to 17 carbon atoms or the radical« CH «CH ~ C ~ OR ^IM and R ^{IM is} an alkyl radical with 1 to 18 carbon atoms, a cycloaliphatic radical, an alkenyl radical with 2 to 18 carbon atoms or an aralkyl radical. 10. A stabilizer according to claim 9 »containing 80 to 90 wt _o - # ^ a Organoainn mercaptocarbonsäureesters the general For" mel III \ ² ) ₄ " _n (III) 1 2 in which R is an alkyl radical with 4 to β carbon atoms and R is an alkyl, aryl, aralkyl, alkaryl or cycloalkyl radical and η is an integer with a value of 1 to 3 , and 10 to 20 wt .- # of the organotin carboxylate of the general formula II.. 11, stabilizer according to claim 10, containing as organotin » mercaptooarboxylic acid ester dibutyltin bis (isoctylthioglycolate), 12 "Stabilizer according to claim 11" containing dibutyltin ~ bis (monoisooctyl maleate) _{0 as the organotin carboxylate} 909819/1238 13 «Stabilizer according to claim 11, containing as organotin carboxylate Dibutyltin dipelargonate. 14. Stabilizer according to claim 11, containing as Organojsinnoarboxylat Dibutyl2inn- »bis ~ (neodecanoate) <, 15 ο Stabilizer according to claim 11, containing as organotin carboxylate dibutyltin-bis- (mono-n »propyl maleate). 16. A method for stabilizing an organotin mercaptocarboxylic acid ester of the general formula I. X ₄ ^ - (I) in which R is an alkyl, oxyalkyl, aryl, oxyaryl »or cyclo * Ester one
alkyl radical and X denotes the / mercaptocarboxylic acid with 2 to 6 carbon atoms, the sulfur atom of which is bonded to the tin atom, and η is an integer with a value of ^: 1 to 3, characterized in that the organotin mercaptocarboxylic acid ester with a stabilizing amount of an organotin carboxylate of the general BOrmel II OC -R " (II) added, in which R 'is an alkyl radical with 4 to 8 carbon atoms and R "is an alkyl radical with 8 to 17 carbon atoms, an alkenyl radical with 8 to 17 carbon atoms or the radical -CHa = CH-C-OR' ¹¹ and R » ^{5 is} an alkyl radical with 1 to 18 carbon atoms, a cycloaliphatic radical, an alkenyl radical with 2 to 18 carbon atoms or an aralkyl radical. 909819/1 238 17. The method according to claim 16, characterized in ^ that as organotin ^ mercaptoearboxylic acid ester Dibutyl tin bis (isooctyl thioglycolate) is used. 18. The method according to claim 16 and 17 »characterized in that about 5 to 70 _{parts by weight 9} - = parts of the organotin carboxylate per 100 parts by weight of dibutyltin bis (isooctylthioglycolate) are used. 19o method according to claim 17, characterized in that; that about 10 to 25 percent ₀ = TeIIe dibutyltin "" up to ~ (monoisooctylmaleat) per 100 parts by weight Dlbutylzinn-bis- (ispoctylthioglykolat) are used, " 20a method of claim 17ι dadurch.gekennzeichnet that about 10 to 25 weight _o ~ ~ dipelargonat parts dibutyltin per 100 weight parts _o ~ ~ dibutyltin bis => (isooctylthioglycolate) may be used. 21. The method of claim 17 'characterized labeled in = records "that about 10 to 25 weight, parts by dibutyltin bis- (neadecanoat) per 100 parts by weight of dibutyltin = = bis (isooctyl thioglycolate ~) _o be used. 22. The method according to claim 17 characterized marked in ₁ · = records that about 10 to 25 weight parts by _e dibutyltin bis- (mono-n-propyl maleate) per 100 parts by weight of dibutyltin Bitis (isooctylthioglycolate) are used *. 909819/1238 The method of claim 16, dadurch.ge ISIN .β B i t without that heating a! Temperature in the range of 71, the mixture dee organotin mercapto carbonsäureestere and a solid .Organozinncarboxylatsauf ⁰ to 82 G, until a clear solution receives, and then cools the mixture. 909819/1238