CA1081445A

CA1081445A - Stabilizer for halogen-containing polymers

Info

Publication number: CA1081445A
Application number: CA266,093A
Authority: CA
Inventors: Franz Scheidl; Herbert Nies
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1975-11-21
Filing date: 1976-11-19
Publication date: 1980-07-15
Also published as: IE43673B1; FR2332296A1; DE2552174A1; BE848608A; DK523076A; LU76240A1; IE43673L; JPS5265545A; GB1524270A; NL7612718A

Abstract

Abstract of the disclosure:
In the stabilization of halogen-containing polymer compo-sitions metal salts of acid boric acid esters are used as co-stabilizers besides the known primary stabilizers, whereby an excellent stabilization effect is obtained without affecting the color of the polymer.

Description

_OE 75/F 812 iO~1~45 This invention relates to the stabilization of halogen-con-taining polymer compositions against the detrimental effect of heat .
In the processing of halogen-containing polymers the poly-mer compositions are generally subject to a considerable ther-mal stress during mixing, grinding and shaping. Polymers and copolymers of vinyl chloride and vinylidene chloride are espe-cially sensitive to the action of heat and light. They become brittle, change their color or are otherwise damaged and, hence, they are no longer suitable for most purposes of application.
Consequently, heat stabilizers are generally added to halogen-containing plastics compositions in order to prevent the poly-mers from decomposing ~r to suppress decomposition as substan-tially as possible.
Suitable heat stabilizers are, in general, lead salts of organic and/or inorganic acids, barium, cadmium, magnesium, calcium, zinc and other metal salts of organic acids or other H-acid compounds, such as for example, phenols and acid esters, and organo-tin compounds. To improve the efficiency of the ~ 20 said primary stabilizers in many cases auxiliary stabilizers or `- costabilizers are required, for example organic phosphites, epoxide compounds, certain nitrogen-containing compounds, poly-hydric alcohols and antioxidants. In many cases, a synergistic effect can be obtained by the concomitant addition of primary , ~
stabilizers and costabilizers.
The stabilizing effect of polyhydric alcohols, such as " .
sorbitol, pentaerythritol, trimethylol propane and glycerol, is described, inter alia, in German Auslegeschriften DAS nos.
29 1,190,659; 1,240,65~; 1,241,106 and 1,252,522. US Patent .
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2,949,439 teaches .hat the boric acid esters of such alcohols can also be used as costabilizers for halogen-containin~ poly-mer comp~sitions. Proper experiments have revealed, however, that with the use of the compounds listed in the aforesaid pub-]ications the addition of the said costabilizers may have a de-trimental effect on the color of the polymer compositions and/or the stability improvement achieved is not fully satisfactory.
It is, therefore, the object of the present invention to ! develop costabilizers on the basis of polyhydric alcohols which ' 10 do not have the aforesaid disadvantages.
It has surprisingly been found that the salts of acid boric acid esters of polyhydric alcohols comply with the aforesaid demands.
Consequently the present invention relates to a stabilizer 15 mixture for the stabilization of halogen-containing polymer com-positions comprising known primary stabilizers and, as costabi-lizers, metal salts of acid boric acid esters o~ polyhydric al-cohols in which the molar proportion of boric acid to polyhydric ,~ 1 alcohol is in the range of from 1:0.5 to ~4, the polyhydric al-20 cohol has the formula Ho-CH2-~CH(oH7n-CH2oH in which n is in the range of from 2 to 5, and the metallic component is the ....
cation of an alkali met~l or alkaline earth metal, of zinc, ~ copper, cadm;um, tin, lead, manganese, cobalt, nickel, aluminum, : zirconium, lanthanum, or cerium. To stabilize the polymer com-position against~the detrimental effect of heat the said metal ~-A, salts are used in an amount of from 0.01 to 5.0 parts by weight .', for ~00 parts by weight of polymer. The invention also relates to polymer compositions which have been stabilized by the afore-. 29 said stabilizer mixture.
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` ! , ' . ,, 108~445 The salts of the acid boric acid esters have a much better stabilizing effect than the free acid esters or the neutral esters of boric acid. They permit subjecting the halogen-con-taining polymer compositions containing same as costabilizer to a thermal stress generally for a period which is by 60 to 100 ~ longer or in some cases even still more extensive. It could not have been foreseen that, compared to some polyhydric alcohols which are known as costabilizers as mentioned above, the initial color and the progression of discoloration, which are very important for the PVC stabilization, are considerably improved. A comparison with the known liquid barium/cadmium/
zinc stabilizers comes also out in the favor of the acid boric acid esters to be used according to the invention which yield better results in the static as well as in the dynamic heat stability test. Furthermore, it could not have been foreseen that the efficiency of the boric acid esters salts of the physio-logically unobjectable or harmless metals, such as alkali me~als, , magnesium, a~m~rNm and so on, does practically not differ frorn that of the boric acid ester salts of metal which arc known to be good stabilizers per se but are toxic , for example the lead, barium and cadmium salts, that is to say that with regard to the intended use of the processed polymer, the costabilizer containing the most appropriate cation can be chosen from a wide range of equally effective costabilizers.
Suitable polyhydric alcohols for the manufacture of the boric acid ester salts are alcohols of the formula Ho-CH2~CH(OH)7n-CH2-oH in which n is in the range of from 2 to 5, preferably 3 or 4 and more preferably 4~ There are Men-2~ tioned, in the first place, sorbitol and mannitol, erythritt)l, . .. , . ., . ~

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HOE 75/F ~12 10E~445 threitol., ribitol., xylitol~ arabitol, dulcitol, iditol, talitol, allitol, D-d-mannoheptitol and D-B-mannoheptitol.
The structure of the acid boric acid esters, obtained by reacting boric acid with the polyhydric alcohol in the pre-sence of water, in which esters the molar proportion of boric acid to polyhydric alcohol is in the range of from 1:0.5 to 1:4, preferably 1:1.5 to 1:3 and more preferably 1:2 to 1:3, ban be derived, inter alia, from US Patents2,223,948 and . 2,224,011. It can be illustrated by way of example by the l 10 following formulae of which formula I represents an ester of ! boric acid and xylitol in a molar proportion of 1:1 and formula II represents an ester of boric acid and sorbitol in a molar proportion of 1:2.

. ,CH2 OH CH2 \e/ 2 CH(OH) I / B
. CH(OH~ CH - O O - CH
CH - O\ CH(OH CH(OH) B-OH CH(OH) CH(OH) . 20 CH2 CH(OH) CH(OH) ~' CH2(OH) CH2(O

: I II

`I The salts to be used according to the invention are pre-1 25 pared from aqueous solutions of the acid boric acid esters by '~. reacting same with metal oxides, hydroxides or carbonates. In the case of metal oxides or hydroxides which do not react di-rectly with the acid boric acid ester, for example aluminum .. .. .
`. 29 oxide, an alkaline earth metal salt of the acid boric acid : _ 5 _ .

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' I~OE 75/F 812 11)t~1~45 ester is first prepared, which is then reacted with the sulfate of the desired metal cation. The precipitated alkaline earth metal sulfate is filtered off.
The salts are isolated from their aqueous solutions by distilling off the water, preferably under reduced pressure.
They are obtained in the form of britlle, well grindable pro-ducts.
Suitable metal cations are the cations of the alkali and alkaline earth metals, of zinc, copper, cadmium, tin, lead, manganese, cobalt, nickel, aluminum, ziconium, lanthanum,or cerium. Cations of the metals of groups I, II and III of the l Periodic Table are preferred, especially magnesium, calcium, L strontium, zinc and aluminum.
The costabilizers according to the invention are used in an amount in the range of from 0.0~ to 5.0, preferably 0.05 to 2.0 and more preferably 0.~ to 1.0 part by weight for 100 parts by weight of halogen-conta~ning polymer to be stabilized.
In accordance with the invention, the acid boric acid esters are used as costabilizers together with known primary stabilizers. As primary stabilizers there are mentioned by ~j way of examplej metal compounds such as calcium, barium , .~ strontium, zinc, cadmium, magnesium, aluminum and lead soaps . ~ .
of aliphatic carboxylic acids or hydroxycarboxylic acid having , from about 8 to 32 carbon atoms, preferably 8 to 24 carbon atoms; salts of *he aforesaid metals with aromatic carboxylIc acids preferably having from 7 to 12 carbon atoms, for example benzoates, salicylates and (alkyl)-phenolates of the said metals in which the alkyl group has 1 to 12 and preferably 1 29 to 6 carbon atoms; furthermore organo-tin compounds, for ex-. .
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10~ 5 ample dialkyl tin thioglycolates and carboxylates as well as neutral and bas~c lead salts o$ inorganic acids such as sul-furic acld and phosphoric acid~ The aforesaid primary stabi-lizers may also be used in the form of mixtures.
The proportion of costabilizer according to the invention to primary stabilizer can vary wi'chin wide limits, it is pre-ferably in the range of from 1:0.3 to 1:10, more preferably 1:1 to ~:3~
It is also possible, of course, to use mixtures of boric : 1 n acid ester salts containing different cations as well as dif-; ferent ester moities. There ;s me~tioned, by way of example, a mixture of the calcium salt and th~magnesium salt of an acid boric acid sorbitol ester or a mixture of the strontium salt of an acid boric acid mannitol e~ter and the strontium salt ~5 of an acid boric acid xylitol ester. Especially good results are obtained with combinations of boric acid ester salts of physiologically unobjectionable or harmless metals, such as ; calcium, maqnesium, sodium, zinc and aluminum, with primary stabilizers on the basis of calcium and/or magnesium and/or ; 2~ zinc carboxylates having from 6 to 40, preferably 8 to 24 car-bon atoms, since combinations of this type can also be con-- sidered unobjectionable from a physiological point of view so that the polymers stabilized therewith can be used as pack-ing material for food. As regards their heat stabilizing pro-perties combinations of this type, in which the ratio of the costabilizer of the invention to the prlmary stabilizer is, ` for example, in the range of from 1:0.3 to ~:10 and preferably ~:2, are superior to the very efective but highly toxic known 29 barium-cadmium stabilizers. Moreover~ some of the aforesaid _ 7 -... .
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stabiliæe~ combinat;ons surprisingly have additionally a notice-; able light stabilizing effect that comes very near to the effect of the barium-cadmium stabilizers. Combinations of this type are, for example, those of the aEoresaid non toxic primary stabilizers on the basis of calcium, magnesium or zinc carboxylates and the strontium and nickel salt of acid boric ; acid esters.
Halogen-containing polymers which can be processed with the addition of the boric ester salts or their combinations are organic polymers containing halogen atoms, preferably chlorine atoms, bound to the polymer chain~ There are mention-; ed by way of example homopolymers of vinyl chloride and vinyli-dene chloride, copolymers of vinyl chloride and vinylidene chloride with other ethylenically unsaturated monomers such as vinyl acetate, vinyl propionate, styrene, methyl methacry-late, acrylonitrile, vinyl ethers, unsaturated acids such as maleic, fumaric, acrylic, methacrylic acid and the mono- or diesters thereof with mono- or dialcohols having from 1 to 10 - carbon atoms; maleic anhydride, maleic imide and the N-substi-tution products thereof with aromatic, cycloaliphatic and op--tionally branched aliphatic substituents. Mixtures of diffe-rent halogen-containing polymers with one another or with poly-mers free from halogen can also be stabilized according to the invention, or example mixtures of polyvinyl chloride with ` 25 ethylene/vinyl a-cetate copolymers or with chlorinated poly-ethylene.
The polymers can be "rigid" or "soft". "Rigid" compositions may additionally contain, incorporated therewith, lubricants, 29 pigments, dyestuffs, fillers, agents modifying the impact ;
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,. : , . -: ,, , 10~1445 resistance, while "soft" polymers additionally contain plasti-cizers such as phthalic acid, adipic acid esters or phosphoric acid esters, plasticizers on the basis of polymers such as low molecular weight polyesters, chloropolyolefins or in some cases also chloroparaffins.
Th~ halogen-containing polymers to be stabilized may further contain, of course, the known auxiliary stabilizers, for example epoxides such as epoxidized soybean oil, tall oil or linseed oil, epoxidized butyl oleate or epoxidized ~-olefins;
i 10 phenolic antioxidants such as 2,6-di-t-butyl~4-methylphenol and 2,2-(4,4'-dihydroxydiphenyl)-dimethylmethane; 2-substituted indoles such as ~-phenyl indole; polyhydric alcohols such as trimethylol propane, pentaerythritol, sorbitol or mannitol; as well as organic phosphites such as triphenyl and trinonylphenyl phosphlte; light stabilizers such as hydroxybenzophenones or ; benzotriazoles. Auxiliary stabilizers and additives of this kind are described, for example, in J~ Voigt "Stabilisierung der Kunststoffe gegen Licht und Warme", Springer Verlag, Berlin-Heidelberg-New York (1966~.
The costabilizers and the known primary stabilizers are added to the halogen-containing polymers in the form of indivi-- dual componen~ or mixtures according to the usual known methods.
The following examples illustrate the invention and the favorable stabilizing properties of the boric acid ester salts in comparison to other stabilizers.
A) Preparation of the boric acid ester salts E X A M P L E 1:
Potassium salt of boric acid/sorbitol-1:2 ester _ g _ ., ~ '' .

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1081~45 HOE 75/F 812 91 ~ (0.5 mol) of sorbitol, 15.5 g (0.25 mol) of boric acid and 100 ml of distilled water were introduced into a 250 ml three-necked flask equipped with stirrer, lnside thermometer and reflux condenser and the contents of the flask were heated for 1 hour to 90 - 95 C.
.
Next, to the clear solution of the acid ester (pH 1 ~
2~ 14.0 g (0.25 mol) of potassium hydroxide were added and stirr~ng was continued for 1 hour at 90 - 95 C. With the aid of a rotary evaporator the water was distilled off from the clear solution having a pH of 7 in a 1 liter flask at a temperature of up to 150 C under a water jet vacuum of 10 to 20 mm.
After cooling of the limpid viscous melt, 97.6 g i~ (98.5 % of the theory) of the potassium salt of boric acid/
~orbitol 1:2 ester were obtained in the form of a vitreous, ; brittle and readily pulverizable mass melting at 105 to', 130R C.
Potassium content found: 10.2 %, calculated 10.0 %.
E X A M P L E 2:
Calcium salt of boric acid/mannitol 1:2 ester In the manner described in Example 1, 91 g (0.5 mol~ of mannitol and 15.5 g (0.25 mol) of boric acid were reacted in 100 ml of distilled water and a clear solution having a pH of 1 - 2 was obtained. After having reacted with 7.0 g (0.125 ~ 25 mol~ of calcium oxide, a clear solution having a pH of 6 - 7 ; was obtained from which 92 g (98.5 % of-the theory) of the calcium salt of boric acid/mannitol 1:2 ester melting at l60 -~, 170 C were isolated.
2' ealcium content: found 4,9 %, calculated 5.3 %.
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Magnesium salt of boric acid/xylitol 1:2 ester 91 g (0.6 mol)of xylitol and 18.9 g (0.3 mol3 of boric ,~ acid were reacted in 100 ml of water in the manner described in Example 1. To the clear solution obtai~ed having a pH of 1, 25.3 g (0.3 mol) of magnesium carbonate were slowly added.
With the evolution of carbon dioxide a slightly turbid solution , having a pH of 6 ~Jas obtained which was filtered and from which 95.0 (99 % of the theory) of the magnesium salt of boric acid/
xylitol 1:2 ester melting at 160 - 180 C could be isolated.
I Magnesium content: found 7.5 %, calculated 7.6 %.
;l E X A M P L E 4:
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,~ Aluminum salt of boric acid/sorbitol 1:2 ester In the manner described in Example 1, 91 g (0.5 mol) of sorbitol and 15.5 g (0.25 mol) of boric acid were reacted in 00 ml of water to yield the acid boric acid/sorbitol 1:2 ester. 23,7 g (0.125 mol) of barium hydroxide monohydrate were added to the solution obtained which resulted in the , --formation of a solution of the barium salt of boric acid/sorbi-., .
; 20 tol 1:2 ester having a pH of 7. A solution of 14.3 g (0.0417 ; mol) of aluminum sulfate in 50 ml of water was added dropwise, the prectpitated barium sulfate was filtered off (29.0 g) and the aluminum salt of boric acid sorbitol 1:2 e~ter was obtained ' by distilling off the water from the aqueous phase having a pH
25 of 3 - 4. Yield-90 g (99.2 % of the theory~, melting range 95 - 110 C~ ~
Aluminum content: found 2.2 %, calculated 2.5 ~, barium content found: less than 50 ppm.
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10819,45 E X A M P L E S 5 to 28:
Further boric acid/polyol ester salts were synthetized in the manner described in the preceding examples. They are listed in the following Table I. Examples 21 and 22 i:llustrate the pre-5 paration of the acid esters on which the ester salts of the in-vention are based and Examples 23 and 24 refer to the prepara-. tion of boric acid esters according to the indications of US Patont 2,949,439 in the absence of w~ter at 120 to 160 C.

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; ` T A ~ L E
boric acid/polyol ester saltsand comparative products Ex.
No. polyol used molar ratio/ cation melting boric acid/ range polyol C
~ 5 sorbitol 1:2 Na 80 - 120 ; 6 sorbitol 1:2 Mg 180 - 195 7 sorbitol 1:3 Mg 105 - 125 8 sorbitol 1:2 Sr175 - 185 9 sorbitol 1:2 Ca 130 - 150 sorbitol 1:3 Ba 85 - 105 11 sorbitol 1:2 Sn-II90 - 110 ,' 12 sorbitol 1:2 Pb-II125 - 140 ~' 13 sorbitol 1:2 Cd115 - 130 i' 14 sorbitol 1:2 Ni-II180 - 195 l 15 sorbitol 1:3 Ni-II95 - 115 ',~ 16 sorbitol 1:2 Cu100 - 120 f7 sorbitol 1:2 Zn165 - 170 18 sorbitol 1:3 Ca/Zn70 - 90 l~ 19 mannitol 1 3 Ca/Zn150 - 170 , 20 mannitol 1:4 Ca/Zn150 - 160 ;~ 21 sorbitol 1:2 H 45 - S0 ~;~ comp.
; 22 mannitol 1:2 H 130 - 140 .~ .
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~ 23 sorbitol 1:2 H 60 - 70 :-! comp-24 pentaerythritol 1:2 H 180 - 200 ,~ comp.

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B) Examples o application E x A M P L E S 25 to 80 Each time 100 par.s by weight of a suspension polyvinyl chloride having a ~ value of 70 were intimately mixed with 2 parts by weight of epoxidized soybean oil, 0.2 part by weight of a montanic acid ester having an acid number of 18 and a ~j saponification number of 154, 35 parts by weight of phthalic acid bis-2-ethylhexyl ester, 0.5 part by weight of calcium , stearate, 0.5 part by weight of zinc stearate and 0.5 part by . .
weight of the respective boric acid/polyol ester salt or compa-rative compound. In Examples 51 and 79, 0.7S part by weight of calcium stearate and 0.75 part by weight of zinc stearate and - in Examples 52 and 80, 0.5 part by weight of calcium stearate and 0.5 part by weight of zinc stearate and no costabilizer were used. In Examples 48, 49, 50, 76, 77 and 78 instead of the co-stabilizer according to the invention, the same amount of a poly-hydric alcohol was used.
To measure the dynamic heat stability the mixtures were l fed to a laboratory two roll mill heated to 180 C and processed .'. .. ~
into a rough sheet for one minute at 20 revolutions per minute.
: ~t intervals of 10 minutes samples were taken from the rough sheet and the color of the samples was compared with a proper color chart. Each time rolling was continued until the rough sheet had acquired a noticeable coloration (cf. Table II).
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In oder to measure the static heat stability the respective mixtures were rolled as described above into a rough sheet which , was further rolled for 10 minutes at ~80 C on the rolls. Flat -.~ ..
samples having a thickness of about 0.5 mm and a diameter of 2~ 30 mm were punched Ollt of the rough sheet removed from the rollr , I .
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; the samples ~iere wrapped in ah~inum foil and heatea to 180 C
in a heating cabinet with air circulation. At intervals of 10 minutes each time one sample was taken from the cabinet and the color thereof was compared with the color chart (cf.
Table III).
In the proper color chart used the individual notes have the following meaning:
1 = water clear . 2 = slightly yellowish 1, , 10 3 - intense yellow color

4 = dark yellow-brown color .

5 = dark brown to blac~

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-- ~08~445 ' T A B L E II
., Dynamic heat stability Ex. boric acid/polyol discoloration of the rough sheet after No. ester salt of ~. rolling time of Example No...... I I _ prcduct 10'¦20' 130' ¦35' ¦ 40' 145' 50' 60' 170 . to color number .
1 1 1-2 _ 1-2 _ 1-2 2 _ 26 1 1 1 1-2 _ 1-2 _ 2 3 _ 27 6 1 1 1 _ 1 _ 2 2-3 _ 28 7 1 1 1 _ 1 _ 1-2 2-3 _ 29 3 1 1 1 _ 1 _ 2 3 3 8 1 1 1 _ 1-2 _ 2 3 _ 31 9 1 1 1 _ 1-2 _ ~ 2-3 3 32 10 1 1 1 _ 1 _ 1-2 3 '_ 33 4 1 1 1 _ 1 _ 2 2-3 _ 34 11 1 1 1 _ 1 _ 2 3-4 _ 35 12 1 1 1 _ 1-2 _ 2 3 _ 3613 - 1 1 1 _ 1-2 _ 2 3 _ 37 14 1 1 1 _ 1-2 _ 2 3 _ 38 15 1 1 1 _ 1-2 _ 2 2-3 _ 39 16 1 1 2, _ 2 _ 2 3 _ 40 17 1 1 1 _ 1 _ 1-2, 2 _ 41 18 1 1 1 _ 1-2 _ 1-2 2 _ 42 19 1 1 1 _ 1~2 _ 1-2 2 _ 43 20 1 1 1 _ 1 _ 1 2 _ 04mp. 21 1 1 1 _ 3 5~ _ _ _ 45 22 1 1 1 _ 3 5 _ _ comp. _ _ _ _ ~ - 16 -, . :: , , ~ . .

` :" 1081445 Ex. ~oric acid/polyol discoloration of the rough sheet after No. ester salt of a rolling time of EXample No or comparative 10'120' 130'35' ¦ 40' 145' 50' 60' 70' : product I l l _ _ . to color number _ _ __ _ _ 46 23 1 1 1 3 3-4 5 _ _ _ comp.
47 24 1 1 1-2 3 _ 5 _ _ comp.
. 48sorbitol 2 2-3 2-3 _ 2-3 _ 2-3 2-3 _ . comp. .
` 49xylitol 2 2-3 3 3 4 _ _ _ _ comp.
. 50 trimethylol l 1 1 _ 2 5 _ _ _ . comp. propane 51 without 1 1 l-2 _ 5 _ _ _ _ comp.
~! 52 without l l 1-2 5 _ _ _ _ _ : ~
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08~445 '` -, T A B L E III :
Static heat stability Ex. boric acid/polyol discoloration of the rough sheet in a No. ester salt of heating cabinet with air circulation after Example No.... .
or comparative10'120' 130'40'¦ 50' ¦ 60' 70' 80' 100' product I I l _ . . _ _to color number _ _ _ ,~ . 53 5 1 1 1 1~ 1_2 2 2 3 5 54 1 1 1 1 1 2 2 3 5 _ ':` 55 6 1 1 1 1 1-2 3~ 3-4 5 _ '` 56 7 1 1 1 1 1-2 1-2 2 3-4 5 ` :
` 57 _3 1 1 1 1 1 2 2-3 5 _ 58 & 1 1 1 1 2 2 3-4 5 _ ,,~ 59 g 1 1 1 1 1-2 2 ,3 4 5 60 10 1 1 1 1-2 1-2 1-2~ 2,3 3-4 5 , 61 4 1 1 1 1 1-2 2 ,3 5 _ . 62 11 1 1 1 1 1 2 4 5 _ . , .
' 63 12 1 1 1 1 2 2-3 3-4 5 _ ,.~ 641,3 1 1 1 1 1-2 2-3 3-4 5 _ 65 14 1 1 1 1-2 2 2-3 4 5 _ 66 15 1 1 1 1 1~2 1-2 2-3, 3-4 5 '. 67 16 1 1 1 1-2. 1-2 2-3 4 5 _ i'i ~ 68 ' 17, 1 1 1 1 1 1-2~ 2-3 5 _ `1 69 18 1 1 1 1 1 1 1-2 2-3 570 1~ 1 1 1 1 1 1-2 1-2 2-3 5 71,20, 1 1 1 1 1 1-~2 2, 2-3 5 ! 72,21 1 1 1 2 5 _ _ _ ' 7co3mp. 2~2 1 1 1 2 5 _ _ _ _ : I comp . ~ _ ~ - 17 --- : , : - - ~: . - -: . ; : . : .

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~- ~081445 Ex. boric acid/polyol discoloration of the rough sheet in a . No. ester salt of heating cabinet with air circulation after EXample No or comparative 0' 20' 30' 40' 50' 60' 70' 30' 100' . to color number . 74 23 1 1 1 2 2-3 5 _ _ _ . comp. .
24 1 1 1-2 2-3 3-4 _ _ _ . comp.
. 76 sorbitol 1 2 2 2 2-3 3 3 3 5 ,~ comp. . .
.. 77 xylitol 1 2 2-3 2-3 3 5 _ _ _ comp. . .
78 trimethylol 1 1 1 1-2 2 5 _ _ _ , comp. propane .
. 79 without 1 1 2 5 _ _ _ _ _ . comp. .
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108i445 ~ E 75/F 812 Examples 25 to 43 and 53 to 71 clearly demonstrate the superior costabilizing effec~ to the boric acid/polyol ester salts. As compared to the PVC stabilized with sorbitol (cf.
Examp~s 48 and 76), the period of stabilization is not so good, on the ayerage, but the initial color and the progression of discoloration, which are very important to the PVC stabilization, are much better.
E X A M P L E S 8~ to 92:
Each time 100 parts by weight of a suspension polyvinyl ~ 10 chloride having a K value of 70 were intimately mixed with ; 35 parts by weight of phthalic acid bis-2-ethylhexyl ester, 0.5 part by weight of decyl-diphenyl phosphite, 0.2 part by weight of a montanic acid ester (acid number 18, saponification number 154) and ~.5 parts by weight of a stabilizer mixture of the invention or of a commercial liquid barium/cadmium/zinc stabilizer. The dynamic and static heat stabilities of the in-dividual compositions was tested.
The stabilizer mixture according to the invention was com-posed of one third of calcium stearate, one third of zinc stearate and one third of boric acid/polyol ester salt. The liquid barium/
, cadmium/zinc stabilizer contained 6.5 % of barium, 3.0 ~ of - cadmium and 0.6 % of zinc in the form of salts of branched ali-; phatic carboxylic acids.

-~, The following Table IV shows that PVC stabilized with the .., ;, 25 mixtures of boric~acid/polyol ester salts, calcium stearate and zinc stearate is superior in the dynamic and in the static heat stability to PVC which has been stabilized with the very effective liquid barium/cadmium/zinc stabilizer. Initial color ,, : .
;' 29 and progression of discoloration of the rough PVC sheet are com-:. ~

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' HOE 75/F 812 ~08~445 parable.
The rough shee-ts of Examples 81, 82, 85, and 86 (rolled for 10 minutes, thickness 0.5 mm) wexe also tested as to their stability to ultraviolet light. After a time of exposure of 8 hours the color of the PVC sheets stabilized with strontium ' and nickel salts of boric acid/sorbitol ester according tothe invention (Examples 82 and 85) was almost as good as tha-t ' of PVC stabilized with barium/cadmium/zinc (Examples 86). In each case, the sheet was clear as water, while in Example 81 " 10 it had a distinct yellowish hue.

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~081445 T A B L E IV
Dynamic and static heat stability .. :
: Ex. boric acid/sorbitol ester discoloration of rough sheet No. salt of EX ............. after a rolling time of or compa~ative product 10' 20' 30' 40' 50' :~ to color number -,., 82. 8 1 1 1 2 5 .,5 84 13 1 1 1 2 5 86 Ba/Cd/Zn 1) 1 1 2-3 5 i comp.
discoloration of the sheet in ~; the drying cabinet with cir-culating air after 10' 20'30' 40' 50' 60' 70' : to color number .~ .
:~. 87 6 1 1 1 1-2 1-2 5 ~' . 88 8 1 1 1 1-2 1-2 5 .'~. 89 12 1 1 1 1 1-2 2-3 5 ,:'5 90 13 1 1 1 1-2 1-2 3-5 5 ' . 91 14 1 1 1 1-2 5 .' 92Ba/Cd/Zn 1) .1 1 3-4 5 ::.,, comp.
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E X A M P L E S 93 to 98:
100 parts by weight of a mass polyvinyl chloride having a K value of 57 where intimately mixed with 3.7 parts by weight of epoxidized soybean oil, 0.3 part by weight of 2 phenylindole 0.5 part by weight of glycerol monostearate, 0.8 part by weight of a partially saponified ester wax on the basis of montan wax having an acid number of 13 and a saponification number of 112, 0.1 part by weight of a polyethylene decomposition wax having a molecular weight of about 9,000, 1 part by weight of a proces-sing auxiliary on methacrylate basis( ~ Paraloid K 120 N of Messrs. Rohm & Haas) and 0.35 part by weight of the stabilizer mixture to be tested.
The stabilizer mixture used consisted of 45 % by weight of calcium stearate, 26 % by weight of zinc stearate, 6 % by weight of 2,6-di-t-butyl-4-methylphenol and 23 ~ by weight of boric acid/polyol ester salt 4~pentaerythritol (for compari-or son).
The test results summarized in the following Table V re-veal that the costabilizing effect of the boric acid/polyol ester salts is distinctly superior in rigid mass PVC to penta-erythritol which is often used in practice.

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' ~ ' ~ . ' , ., ' ' , ' ~: 1081445 HOE 75/F 812 T A B L E V

Ex. Dynamic and_stati heat stabi.tlty No. boric acid/polyol ester discoloration of rolled sheet salt of Example No. after a rolling period of or comparative sub- 10'20' 30' 35' 40'50' 60' stance to color number 93 6 1 2 2-3 - 3 3-~ 5 94 9 ~ 2 2~3 - 3 5 pentaerythritol 1 2 2-3 5 - - -colnp-:, ; discoloration of rolled sheet in .. ` heating cabinet with air cir-culation after ~0' 2Q~ 30' 40' 50' 60' 70' 80' ; to color number , ....................................................................... .

.', 98pentaerythritol 1 1-2 2-3 2-3 3 5 - -::; comp.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A stabilizer mixture for use in the the stabilization of halogen-containing polymer compositions, comprising at least one primary stabilizer and a costabilizer selected from the group of metal salts of acid boric acid esters of polyhydric alcohols in which the molar proportion of boric acid to poly-hydric alcohol is in the range of from 1:0.5 to 1:4, the poly-hydric alcohol having the formula HO-CH2[CH(OH)]n-CH2OH
wherein n is in the range of from 2 to 5 and the metal compo-nent is the cation of an alkali metal or alkaline earth metal, of zinc, copper, cadmium, tin, lead, manganese, cobalt, nickel, aluminum, zirconium, lanthanum, or cerium.

2. A stabilizer mixture as claimed in claim 1 containing at least one additional costabilizer.

3. A stabilizer mixture as claimed in claim 1 in which the primary stabilizer is selected from the group of metal compounds from the group of calcium, barium, strontium, zinc, cadmium, magnesium, aluminum and lead soaps of an aliphatic carboxylic acid or hydroxycarboxylic acid having from about 8 to 32 carbon atoms, salts of these metals with aromatic carboxylic acids, organo-tin compounds and neutral and basic lead salts of inorganic acids.

4. A stabilizer mixture as claimed in claim 1, claim 2 or claim 3 in which the proportion of costabilizer to primary stabilizer is in the range of from 1:0.3 to 1:10.

5. A stabilizer mixture as claimed in claim 1, claim 2, or claim 3 in which the proportion of costabilizer to primary stabilizer is in the range of from 1:1 to 1:3.

6. A process for the stabilization of a halogen-containing polymer composition against the detrimental influence of heat in which a stabilizer mixture is added to the polymer, said stabilizer mixture comprising at least one primary stabilizer and a costabilizer selected from the group of metal salts of acid boric acid esters of polyhydric alcohols in which the molar proportion of boric acid to polyhydric alcohol is in the range of from 1:0.5 to 1:4, the polyhydric alcohol having the formula HO-CH2-[CH(OH)]n-CH2-OH in which n is in the range of from 2 to 5 and the metal component is the cation of an alkali metal or alkaline earth metal, of zinc, copper, cadmium, tin, lead, manganese, cobalt, nickel, aluminum, zirconium, lanthanum, or cerium, the said metal salt being used in an amount of from 0.01 to 5.0 parts by weight per 100 parts by weight of polymer to be stabilized.

7. A process as claimed in claim 6 in which the primary stabilizer is at least one member of the group of calcium, magnesium and zinc carboxylates and the metal component of the costabilizer is selected from the group of sodium, potassium, strontium, calcium, magnesium and aluminum.

8. A halogen-containing polymer composition containing the stabilizer mixture as claimed in claim 1, in an amount of from 0.01 to 5.0 parts by weight per 100 parts by weight of polymer.

9. A halogen-containing polymer composition as claimed in claim 8 which contains at least one additional costabilizer and which may contain at least one further additive selected from the group of antioxidants, plasticizers, fillers, lubricants, pigments, and dyestuffs.

10. A halogen-containing polymer composition as claimed in claim 8 or claim 9 in which the polymer is selected from the group of homopolymers of vinyl chloride, homopolymers of vinylidene chloride and copolymers of vinyl or vinylidene chloride with other ethylenically unsaturated monomers.

11. A stabilizer mixture as claimed in claim 1 in which the primary stabilizer is at least one member of the group of calcium, magnesium and zinc carboxylates and the metal component of the costabilizer is selected from the group of sodium, potassium, strontium, calcium, magnesium and aluminum.