CA1094726A - Stabilization of vinyl resins - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE:

Synthetic compositions based on vinyl polymers or copolymers are stabilized against degradation by heat and light by the incorporation therein of a 1,4-dihydropyridine derivative represented by the general formula:

Description

10~4726 The present invention is concerned generally with the stabilisation of vinyl resins, including the vinyl copolymer.s, by means of dihydropyridine derivatives, certain of which are novel.
The stabilisers according to the invention conform to the general formula:

O O
Il ,~ 11 RO-C-~ ~-C-OR
3 ~N~ 3 ' in which R represents:
- an alkyl radical containing from 1 to 22 carbon atoms, - an octadecenyl radical, - a cyclohexyl radical, or - a phenyl radical, optional.ly substituted by a halogen atom or by a methyl or methoxy radical.
Quite generally, the dihydropyridines which are used according to the invention may be prepared by the method proposed by HA~TZSCH, Chemical Reviews, 72, 1, 1972, which consists in causing the reaction of an acetoacetate of general formula;
CH3-CO-C~2-COOR II

~ 10~726

-2-in which R assumes the same ~alueæ as in formula 1, with formaldehyde and ammonia, possibly formed in situ.
A6 regards the acetoacetates of formula II, these may be prepared in two ways :
- either by action of the diketene of formula C=C-O\
C~2-C=O
on an alcohol of formula R0~, in the presence of sodium acetate, -or by transesterification between the methyl acetoacetate and an alcohol of formula R0~, it being under6tood that, in the for~ula ROH, R represents the 6ame values as in formula I.
It is known that the vinyl resins have a tendency to be degraded under heat and that it i~ essential to introduce stabilising agents into these compo~itions consisting of synthetic material, with a Yiew to retarding the degradation due to heat and hence the coloration of thefie compositions Among the or~anic compounds which are known for their effect in stabilising vinyl resins against heat, it is possible to me~tion the compounds of formula I, in which R represents an ethyl or butyl radical, The later mentioned French Patent No 2,239,496 does in fact 6how that the two abo~e compounds thermally and chemically stabili6e the vinyl resins into which they are introduced at the rate o~ 0.2 to 1 5 ~ by weight.
Particularly known as a heat stabiliser is 2-phenyl indole, which ifi found to be of particular intere6t, on account of its stabilising power and it6 low toxicity. Moreover, it is widely used on an industrial scale for stabilising the vinyl polymers and copolymers, especially tho6e which are used in the composition . -3-of food packaging materials. 10947~
It has surprisingly been found that the compounds according to the invention, when incorporated into a vinyl resin at the rate of 0.01 to 0.5% by weight, stabilise the said resin against light, while conferring a satisfactory thermal stability to said resin, despite the low concentration which is u6ed This discovery is very important, especially in respect of the resinc which are used in food packagin~ materials.
It is actually obvious that it would no be possible to market foods in a package of which the colouring ~aries over a period of time.
In addition to their photostabilising effect, it has also been discovered that the dihydropyridines according to the invention :
-present a heat-6tabilising action on the polyvinyl chloride at concentrations which are between 0.01 a~d 0.2 p.c r (part per 100 parts of resin).
Thi~ discovery is important, because it thereby becomes possible to ~isualise the use of polyvinyl chloride as thus stabilised as a packaging for food commodities~ At these conce~trations, the extraction of the stabiliser by the foods i8 extremely small if not negligible, whereas at concentrations higher than 0.2 p.c.r , it becomes con~iderable a~d does not permit of this application bei~g considered for certain deriYative6 of formula I.
It has,~oreover, been disco~ered that the extraction or migration of the 8tabiliser - just li~e ~ts su~limatio~ -varied with the number o~ carbon atoms in the chains R
The concentration of ~tabl~iser being used may be brought up to 1 p.c.r. when it i9 a Question of stabilising viny~
polymers intended for uses as the manufacture of 100r coverings or recording discs.
- exert a lubricating power on the vinyl resins, - permit, in the resins which contain calcium and calcium-zinc salts as primary stabilisers, of reducing the amount of zinc without as a result decreasing the stabilisation of the resin.
Now, it is known that a too high proportion of zinc causes the appearance of defects in the resin.
-offer the possibility of using them at a concentration which i6 between 0.1 and 0.2 p.c.r. for the ætabilisation of vinyl resins which contain a plasticiser, such as dioctyl phthalate.
This type of resin generally contains barium-cadmium and calcium-zinc salts as primary stabiliser~ and it has been established that the additicn of a s~all quantity of a dihydropyridine according to the in~ention make6 it possible to reduce the proportion of cadmium, whick is a ~ery espenBive and toxic product, without reducing the thermal stability of the resin Furthermore, the compounds according to the invention appreciably improve the basic shade of this type of re8in, the said shade co~ing close to being colourless.
- offer the pos6ibility of the waste product of poly~inyl chloride, stabilised by the dihydropyridines of formula I, being recycled on machines operating by e~trusion and blowing, prove the basic shade and increase the stability of the eolour of the res~n6 containing a dye, - pro~ide a greater antioxidising effect than, for example, that of 2,6-di-tert -butyl-4-methyl phenol, which is an antioxidant widel~
used in connection with vinyl resin~, -5 10~ ~72~;
- offer the possibility of advantageously replacing the stabilisers for vinyl resins as so far used, na~ely, 2-phenyl indole and its derivatives, the aminocrotonates of heavy alcohols or polyols and the tin derivatives, with the advantage of obtaining :
. a good thermal stability at lower concentrations which are capable of being between 0 01 p.c.r and 0.2 p.c.r., with the consequence of thereby decreasing the cost of sta~ilising the resin, . a good resistance to light, . an improvement in the initial colour of the resin and the de~elopment of the colour as a function of time.
As has already been previously mentioned, it has been established that the compounds according to the invention also exert thermostabilising and photostabilising properties on the vinyl chloride copolymers (vinyl chloride - vinyl acetate, vinyl chloride-vinylidene chloride, ...). They make possible the stabilisation of the formulae which al60 correspond to rigid and pliable copolymers.
~ 6 regards the different applications which are involved (manufacture of recording discs, flooring tiles, pliable sheets for various packaging purposes, .. ), the compounds of formula (I) have to be incorporated into the vinyl resins in quantities ~hich ~ary from 0,01 to 1 p,c.r. (part per 100 parts of resqn) and preferably bet~een 0 01 and 0.5 p.c.r. .
~ he dihydropyridines of ~or~ula (~) are compatible wit~ the different varieties of vinyl resins which are available on the ~arket at the present time, as well as copolymers By way of example, it is possible to use the following resins, which are obtained by suspension polymerisation and as listed below :

~ 1~
,~
. ~

. -6- l O 9~ ~

. Nature of copoly~er Commercial name Supplier :Vinyl chloride-vinyl acetate :with 15% of acetate : Lucovyl MA 603~ : R~ONE-POULENC
:Vinyl chloride-vinyl acetate : : :
:with 15% of acetate: Lucovyl SA 6001 : RHONE-POULENC

:Vinyl chloride-vinyl acetate with 12 5_13 5% of acetate . Vinnol ~13/50 S WACKER

:Vinyl chloride-vinyl acetate with 15% of acetateSolvic 547 SA SOL~AY

:Vinyl chloride-~inylidene :chloride with ?0% of :~inylidene chloride: Ixan S~A/1 : SOLVAY
:
It is understood that these examples are not in any way of limiting character.
For the preparation of certain of the composition6 of resins which have been tested, polyvinyl chlorides have also been used in certain cases, such as those marketed under the names :
. Lucovyl MB 1000 (supplier REON~-PO~LENC) . Lacqvyl S.071/S ~6upplier A~O-CHIMI~) . Solvic 223 (supplier SOLVAY) ~ rom the tests which were carried out, it has been possible to show that :
- by comparison with the same copolymers used under the same conditions, but without incorporation of this type of ad~uvants, the dihydropyridines of for~ula (~) 6tabilise the vinyl copolymers with respect to heat and light in a ma~ner without any q~estion ;
- the dihydropyridines of formula ~I) are s~own to be decidedly better than the amino~rotonate~ of alcohols or of polyols for stabilising the vinyl copolymers with respect to heat and light. These observations have been essentially noted in respect of butane-1,4-diol bis-aminocrotona and the aminocrotonate of C16-C1g alcohols. These results have been obtained for formulae which yield rigid copolymers and flexible copolymers ;
- the dihydropyridine6 of formula (I) show thermostabilisin~ and photo-stabilising properties which are ~ery much better than those of the 2-phenyl indole which is frequently used in rigid and flexible formulae for stabilising the vinyl copolymers.
As for polyvinyl chloride, the use of the 1,4-dihydropyridines of formula (I), and especially those of high molecular weight, improve~
the bonding time for the formulae of copolymers which they stabi1ise.
Particularly as regards the vinyl chloride-vinyl acetate copolymers, it ha6 been shown thatt with equimolecular concentration, the lubricating power of the didodecyl derivative of formula tI) (R = n-C12H25-) and of the compound o~ formula (I) resulting from Acropole 35 (~ = C12~25 to C1sH~1~ straight-chain or branched-chain) was decidedly better than that of the dimethyl deri~ati~e of formula (I) (R = -C~3) The 1ubricating power of the dihydropyridines of formula (I) is at least comparable and gener~1ly is better than that of the aminocrotonates of alcohols or of polyol~. From this point of view, the result is that it is possible to substitute the dihydropyri~ines of formula (I) ~or the aminacrotonate6 in certain application~, for which a good lu~ricating power is appreciated, as is the case with the manufacture of recording discs.
lt has frequently ~een 0~6erved that, in the compositions .

under examination, the dihydropyridines of formula (I) were able to be used in amounts considerably smaller than the aminocrotonates or the 2-phenyl indole. This possibility produces an economic interest which cannot be inconsiderable as regards these molecules.
The invention i9 now to be described in detail, both at the level concerned with the preparation of the compounds according to the in~ention and at the level of their properties.
1 - PREPARATION OF TH~ PRODUCTS
1.1. - Preparation of the acetoacetates, synthesis intermediaries They were obtained by transesterification between an alcohol RO~ and methyl acetoacetate. The synthesis is carried out under nitrogen in the presence of an excess of methyl acetoacetate used as reactant and solvent (3 to 4 moles of methyl acetoacetate per mole of alcohol).
The methanol which is freed is eliminated by continuous distillation until about 170C is reached~ in the reaction medium, and then the methyl acetoacetate excess is distilled under reduced pressure (pressure of 2 to 3 mm Hg ; temperature : 155 + 5C).
The quasi-total elimination of the methyl acetoacetate is important for preventing the presence of mixed dihydropyridines in the product.
~ he expected acetoacetate is directly used in the crude state for the continuation of the synthesis. The yield is from 95 - 100%
A more specific example a~ regard~ preparation is hereina~ter descri~ed :

. .

1094qZ6 Preparation of dodecyl acetoacetate Introduced into a reactor equipped with a stirrer mechanism, a Vigreux column head and a reflux condenser are 464 g (4 moles) of methyl acetoacetate and 186 g of dodecyl alcohol. The temperature of the reaction medium is progressively raised to 165C and the methanol having f~rmed i5 distilled until the reaction is terminated, that is to say, for about 8 hours. The methyl acetoacetate excess i8 eliminated under a reduced pressure of 8 mm Hg and the crude dodecyl acetoacetate is recovered, and this will be used as such for the preparation of the corresponding dihydropyridine derivative (Example 3).
The general method as described abo~e was observed for the preparation of the acetoacetates listed in the following table, these serving as synthesis intermediaries for the preparation of the correcponding derivatives of the dihydropyridines.
In this table and the following tables, the following are represented by the various abbreviations : MW : molecular weight, MP : melting point, GPC : gaseaous phase chromatography, Yd. : yield, Pt : product, min. : minute, sec. : second.
The mixtures of industrial alcohols which are used and which are indicated by their commercial names are t~e following :
Dobanol 23 tsupplier : SHEL~-C~lMI~) is a mixture o~ primary and straight-chain synthesis ~atty alcohols having 12 or 13 carbon atoms;
Dobanol 2~ (supplier : S~LL-C~IMIE) is a mixture of pri~ary and straight-chain synthesis fatty ~1cohols having ~rom 12 to 15 carbon atoms;

_10--Acropole 35 ~supplier : PUK) is a mixture of primary, straight-chain and branched-chain synthesis fatty alcohols having from 12 to 15 carbon atoms ;
Oleocetyl alcohol (supplier : HENXEL) is a mixture of natural fatty alcohols comprising from 12 to 20 carbon atoms (es~entially from 16 to 18 carbon atoms).

_ . . . _ _ . . , ~ ., 0~ ~'726 : Acetoacetic e~ters : :Xydroxyl :Composition :Molecular : . d Nomenclature Supplier . Ylel : : : index : by GPC : welght :Dobanol 23 (straight- : : : : : :
:chain primary synthe- : : C 34 9%
:8i8 fatty P1cohols) : : 12~
: :SHELL CHIMIE: 272.5 : C13: 46.4%: 289.8 : 100%
: Cn~2nl1_OH
: n = 12 to 13 Mean MW 194 : MP 21-22C
.
:Dobanol 25 (straight- : : .
:chain and primary : : : C12: 20.1~: :
:synthesi6 fatty : : : : : :
:alcohols) :SHELE CHIMIE: 258 : C13: 27~4X: ~o1,4 95 ~ nn2n+12 t 15 ' : Mean MW 207 : MP 21-23C : : C15: 14,4%:
:
-:
:Acropole 35 (branched-: : : : : :
:chain primary synthe- : : : C12: 20.9~: : :
: 8i~ fatty alcohols :UGINE-CnH2n+1 OH :KU~EMANN : 271 : C1~: 51.9~: 291 : 100~ :
: n = 12 to 15 : MW 208-211 MP 21C : : : C1s: 15.3%:
:(1_Decanol) ~tearyl :alcohol :CH (C~2)16-CE20R :LASERSON : 195.5: C1g: 93.6%: ~71 : 98%
: ~W 270 :SABETIER
: MP 56 - 600C
. ; . , , . :
;Oleocetyl alcohol : : : C14: 4~ : :
(mixture of natural :H~NK~L : 218.3 ;fatty acid6) : : : C16: 25.2~: 340.9 : 98,5%^ MP 20-30C
; : : : C1~: 62% : : :
:~1_Docosanol) :behenylic alcoho1 : MW ~26 :M~RCK 16g.7 : 410.6 : 100%
: MP 65_680C
:~cis-9-octadecen-1-o?):
:oleyl alcohol :GI~A~AN : 209.3 : : : 95 : ~W ~68 : ~P 13-19C

1.2 - Preparation of the derivatives of 1,~l-dihydro~yridines of formula (I) 1.2.1 - Starting from the formaldehyde and the ammonia introduced as such into the reaction medium.
EXAMPL~ 2 PreRaration of 2~6-dimethyl-3,5-dicarbomethoxy-1,4-dihydropyridine 23.2 g (0.2 mole) of methyl acetoacetate and 0.2 g of diethylamine are introduced into a reactor which is cooled by an ice bath. The solution is cooled to 0C and 7.5 g (0.1 mole) of formic aldehyde in 40~ aqueous solution are added dropwise, while ensuring that the temperature is kept below or equal to 10C.
The reaction medium i6 then kept for 6 hours at 0C and then for 40 hours at ambient temperature.
The solution is poured off and the aqueous phase is extracted with ether, whereafter the organic phases are reunited and the solution is dried over anhydrous sodium sulphate.
Filtration takes place and the ether is eliminated by evaporation, whereafter the oily residue is diluted with ~ part of methanol. While keepin~ the temperature at 0C, ammonia is caused to bubble into the solution and then the ammonia~
saturated solution is kept at ambient temperature for 12 hours The solution i6 suction-filtered and the product which is obtained is recrystallised from methanol and then from acetone.
The 2,6-dimethyl-3,5-dicarbomethoxy-~,4-dihydropyridine is obtai7ed with a yield of 86~.
Melting point : 232C.
By o~erating in the ~ame manner, the following products are prepared :

~.

: Alkyl : 1,4-dihydropyridines (I) : acetoacetate : ~ : Yield : Recrystallisation : M.P.
: used : : : sol~ent :-- :
: Ethyl : acetoacetate : -CH2-CH3 : 75% : acetone : 196C
:
: Octyl : acetoacetate : -(CH2)7CH3 : 37% : acetone : 92C
:
: Isopropyl : /C~3 : acetoacetate : -CH : 8~% : isopropanol : 124C
: : ~ CH3 :
: Dodecyl : acetoacetate : -(CH2)11CH3 : 52% : acetone : 960c :
: Cyclohexyl : : : hexane/benzene : acetoacetate : - ~ ~ : 16,5~ : 80/20 103C
,~
:
: Propyl : acetoacetate : -~CH2)2CH3 :36% : benzene : 148C

Tert butyl ; / 3 : acetoacetate : -C - CH3 : 55X : benzene : 166C
\ CH
: : 3 :
1.2.2 - Starting from the formaldehyde and the ammonia formed ln situ in the reaction medium.
General operating ~rocedure :
Into a 1-litre reactor equipped with a reflux condenser are introduced :
Crude acetoacetate 1 mole ~ethanol 320 cc Puri~ied water ~7 g A~monium acetate 14,4 g ~examethylene tetramine 35 g The batch is ref~uxed while ~tirring and ~n~er a nitrogen stream.
As this takes place, the mass becomes progres~i~ely li~pid.

lOg4726 It ~s kept under reflux for 2.5 to`3 hours and there is obsorved the formation of a precipitate or, according to the tests, the demixing of an oil.
After return to ambient temperature, the said temperature is maintained at -5C/-10C for 2 hours, followed by suction-filtering.
The ammonium ions and the hexamethylene tetramine are then eliminated by thorou~h rinsing with pure water and washing is carried out with heptane in order to eliminate the corresponding puridine formed by oxidation, so as finally to dry to constant weight in a vacuum oven (50C/10 mm Hg) More specific embodiments of this general process are set out below :

Preparation of 2,6-dimethyl-3,5-dicarbododecyloxy~,4-dihydropyridine Into a reactor are introduced 54.0 g of dodecyl acetoacetate, 10 5 g of hexamethylene tetramine, 2.9 g of ammonium acetate, 6 5 g of methanol and 8.o g of water While stirring, the temperature of the reaction medium is raised in 45 minutes to the reflux temperature of the methanol and the refluxing i8 maintained for ~ hour. ~he suspension is allowed to cool to ambient temperature and then it is poured into a mixture of 300 g of water and ice (50/~0) Stirring takes place ~or ~ hour in order to eliminate the excess hexamethylene tetramine.
Suctio~-filtering takes place and the product is taken up in ~00 g of water S~irring is ~arried out, followed by another suction-filtering operation and final~y the product ic recrystalli~ed ~rom 400 g of acetone 1og4q26 \

The 2,6-dimethyl-3,5-dicarbododecyloxy-1,4-dihydropyridine is obtained with a yield of 73.5%.
Melting point : 960C.
By operating in the same manner, the following products are prepared :
: Acetoacetate : Dih dro- ~ :
: used : ~ : Recrystallisation: MP
~ olvent :
Phenyl : ~ : : : :
; acetoacetate : -~ ~ : 4% : dimethylformamide:239C :
:
: p-~olyl : acetoacetate : - ~ -CH3 : 32% : ethanol/acetone :214C :
~ ~ : : 90/10 : : : : :
p-Anisyl : : : :184C :
: acetoacetate : - ~ ~ -OCX3 : 34% : acetone :then ~\ ~ :195C :
:
: p-Chlorophenyl : acetoacetate : -~ ~-Cl : 14% : acetone :227C :
~/!

: ~utyl : acetoacetate : -(Cx2)3cH~ : 58~ : methanol 122C .
Decyl acetoacetate _(CH2)9CH3 : 64% acetone g50C
: Tetradecyl _(CH2)13CH3 : 65~ : acetone : 960C .
: acetoacetate :
: Octadecyl -(CH2)17CH3 7~ :103C
: acetoacetate : Octadecenyl :-cH2-(c~237-c~ :
: acetoacetate : ~ 91,9% : : 560C -CH3-(C~2)7 C
: ~ocosanyl : -(C~2)21C~3 : 75,6~ : :106C
: acetoacetate : : : :
:

~094726 The last of these compounds is obtained in the form of a yellow pasty product, whereas the two preceding compounds assu~e the form of a yellow powder.

1,4_Dihydropyridine~, deri~ing from mixtures of natural or 6ynthetic indu~trial alcohol~, haYe also been prepared and these co~pounds are listed below.

: acetoacetate : ppearance : ~P
: used : : MW :

: Crude tridecyl : acetoacetate :CH3(C~2)n~ :574 :76%:yellowish- 890C
: (Alcohol : : : ::green powder :
: Acropole 35 :n : 11 to 14 : : : : : :
Crude tridecyl CH3(C~ )n~ 572 45.4~-yellow .890C
acetoacetate 2 . . powder ; ~lcohol: Dobanol 23)n : 11 or 12 : Crude tridecyl :CH3(C~2)n~ :595 :78% :yellowish- 890C
: acetoacetate : : : :green powder :
: SAlcohol : :n : 11 to 14 : Dobanol 25) ~ --.
: Crude oleocetyl :CH3-(CH2)15-: acetoacetate : : : : :
: (Alcohol : :CH3(CH2)7CH=CHscH2)n ~75 41~ yellow .81oc: H.D Oceno~) : powder : :n : 6 to 8 :

_17-2. Properties of the products For simplification purpo6es, reference will be made to the main compounds of formula (I) as investigated and they will be repre6ente~ by their code number shown in the following table.

__ O O
BO-C- ~ -C-OR
X3C_ ~ ~ -C~3 I

~ 094726 R ; Code No, --CH2-CH3 . L .28501 -(C~2)7-cH3 ~ L,28502 . -CH3 . L,28504 . -CH . L . 28506 ~ CH3 - ( C~2) 11 -C~3 . L, 28507 ~ - O . L .28508 ~ ( C~2) 2CH3 L .28509 -C(C~3)3 L.28510 . /~ : L. 28531:
. ~-Y

L .28538 .
_ ~y, _~CH3 . L,28541 _ ~ -Cl ~ L,28551 - ( CH2) 3C~3 L .2&552 -(C~2)~3CX3 : L.28590 . -(CE23g-~3 : L.28591 ~9 . _C12X25 to -C15H31 ) L 28596 _ (CH2)n-CH3 ~ -with n = 11 or 12 ) L, 28597 n = 11 to 14 ooo) . L 28598 ( CH2) 17-C~3 L 28599 ¦-CH2- ( CH2) 7-CH=CH- (CH2) 7-CH3 ) ~(CH2)15-C~3 - ( CH2) 21 -CH3 L 28601 ) Acropole 35 C12-C15 ) DObanO1 23 C12-C13 OOO) DObanO1 25 C12-C15 ooo) H.D. Ocenol C16-C18 The toxicity of the photostabilisers according to the invention was primarily established and the satisfactory results which were obtained permitted the investigation to be continued, 2.1. _ Study of acute toxicity The acute toxicity of the compounds according to the invention was studied, by determining the dose of product which causes 50 death of the treated ani~als ~D90).
The determination or typing is achieved by oral ad~inistration o~ a gummy suspension of the compounds to batches of at least 10 ~ice or 10 rats.
The results as observed show that, as regards these t~o animal species, the LD50 is, for the molecules, higher than 2 g/kg and frequently higher than 5 g/kg, Furthermore, no toxic symptom was found, after an obser~ation period Of 15 days.
2.2 - Study of the migration ~ he migration or the extractability of the stabiliser from the PVC compound under the effect of various liquids (and particularly water) stored in a plastic container is of essential importance for the use of these stabilisers in the field of food packagings. The migration of the dihydropyridines (1) in water has been thoroughly in~estigated b~ comparison with the 2-phenyl indole, which is ~ept as reference molecule.
The technique as regards extraction was the following :
using the formula which is given below, a batch of bottles (volume 1 litre, diameter 70 mm, height - 230 mm) was prepared, the said bottles being filled with a liquid simulating foods. Under these conditions, the volume/surface ratio (volume of the liquid and surface of the bottle in contact) is close to 1.85. The migration of the stabiliser was judged by dosage of the pyridine present in the extractum, using the dosage method which is later described. This pyridine ob~iously represents the oxidised form of the extracted 1,4-dihydropyridine~
The investigation was particularly devel~ped for water àt gooc oYer a period of 2 months, because it represents the important problem regardsng the packaging of mineral waters -21- `
Ingredient~ Parts by weight Polyvinyl chloride re~in 100 Anti-6hock agent 8 Epoxidised soya oil 4 Acrylic resin 0.5 Trinonyl phenyl phosphite 0.3 SL 2016 0.25 Calcium behenate .4 Glyceryl trimontanate .4 Hydrogenated castor oil 1 2 Stabiliser - 0 015 to 0.5 The SL 2016 is a solution of zinc 2-ethyl hexanoate in a mixture of aromatic hydrocarbons boiling from 158 to 184C.
2.2.2 - Dosage method The stabilisers are measured out in the form of their oxidation product (pyridine) The oxidation i~ made quantitati~e by adding a few drops of iodine to the ~olution. ~he latter is then extracted with chloroform and the chloroform is e~aporated to a small re6idual volume. The solution obtained is then subiected to thin-film chromatography, by comparison with 60lutions of known concentration of the desired pyridines.
The sensiti~ity thre~hold of this technique is 5 ~g/litre.

The invefitigation was carried out on the following compounds :
2,6-Dimethyl-3,5-dicarbomethoxy-1,4-dihydropyridi~e (L 28504) 2,6-Dimethyl-~,5-dicarboethoxy-1,4-dihydropyridine (~.28501).
2,6-Dimethyl-3,5-dicarbobutoxy-1,4-dihydropyrine (L.28572)~
2~6-Dimethyl-3t5-dicarbododecyloxy-1~4-dihydropyridine (T 28507) 109~7Z6 2,6-Dimethyl-3,5-dicarbotetradecyloxy-1,4_dihydropyridine (L 28590) 2,6-Dimethyl-3,5-dicarbooctadecyloxy-1,4-dihydropyridine (L.28599).

: Extrac- : Stabiliser Migration in ~g/l at 50C
medium Nature :Concen- . 10 : 20 : 1 : 2 : : :tration : days : days : month : months : -: : :in pct L.28504 0;15 15 4 . 7 L.28504 0.3 : 7 : 100120 : ~20 ~.28501 0.15 20 50 100 100 L.28501 0.30 90 : 120: 150: 150 Control 0.30 70 9 100 100 :
L.28552 0.15 15 40 9 100 L,28552 0.~0 :80 : 120: 130: 130 Control 0.30 80 100110 110 . Water .
L.28507 0.30 ~ 5 ~ 5; ~ 5 ~ 5 Control 0.30 75 9 100 100 L.28590 0.15 ~ 5 ~ 5 ~5 ~ 5 ;. ~.2~590 . 0.30 . ~ 5 : ~ 5: ~5 ~ 5 Control 0.30 ~5 9 110 110 . L 28599 ~.15 ~ 5 ~ 5 C5 ~ 5 :: T-.28599 : 0.30 : ~5 : ~ 5: ~5 : ~5 Control 0.30 70 . 9 120 ; 130 Contro1 - 2-phenyl indole It is appare~t from this inve~tigation that - the dihydropyridinea are clearly less extractable than the 2-phenyl indole, - the 6tabilisation of ~he ~inyl resins bg the dihydropyridines accordin~
to the invention need concentrations which are far smaller than those required by the 2-phenyl indole, the result belng an eYen greater reduction in the migration, - in the series of 1,4-dihydropyridines (I) for which R comprises from 9 to 22 carbon atoms, the migration in the water de~elops according to the number of carbon atoms forming the radical R of the formula (I), 1094'726 -23- .
this being concurrently with the sublimation, as will later be seen, - for values of R comprising from 1 to 8 carbon atoms, the migration is considerable and of the order of that generally observed for the 2-phenyl indole, i.e. from 80 to 120 ~g per litre, - for ~alues of R comprising from 1 to 8 carbon atoms, a maximum of migration seems to be obser~ed for R = 2, 3, 4 carbon atoms, - for values of R co~prising from 1 to 8 carbon atoms, the ~igration increases with the concentration of the stabiliser in the PVC compound, - for values of R comprising from 9 to 22 carbon atoms, and particularly for R = 12, 14 and 18 carbon atoms, the migration in the water is below 5 ~g/l, whatever the concentration of the stabiliser in the PVC compound between 0 01 and 0.5 p.c.r., ~p c.r. = part per cent, parts of resin). In fact, the migration has to be clearly smalles than 5 ~g/litre, but this estimation is limited to this value by the sensitivity threshold of the technique used for the dosage.
It can be concluded therefrom that the dihydropyridines (I), of which the radical R varies between 9 and 22 carbon atoms, are capable of being ~sed for stabilising the PVC intended for the packaging of mineral waters, whereas those in which R Yaries between 1 and 8 carbon atoms are not suitable for this purpose, because of their too high migration.
For justifying the possibility of using the dihydropyridines (I) having a radical ~ comprising from ~ to 22 carbon atoms in applications concerned with food packaging, other than those applications relating to mineral waters, the extractability of the dihydropyridines ~y everal solutions or solvents having the following composition, by weight, was investigated :

-24_ .
(a) Water-sodium chloride 97-3 (b) Water-saccharose 90_10 (c) Water-sodium chloride-acetic acid 98.5-0.5-1 (d) Water-citric acid (solution at p~=5) 98-2 (e) Water-acetic acid 97-3 (f) Water-acetic acid S0-10 (g) Water-ethanol 85-15 (h) Water-acetic acid 50-50 (i) Water-ethanol 50-50 (j) pure heptane 50-5 The results obtained are set out in the following tables :

- - 2 g -: Lxtraction : Stabiliser : ~ :
: Medium: 0,3 p.c,r. : 1 month : 2 months : : Phényl-2 indole : 90 : 140 :
L.28504 ; 100 120 :H20 / NaCl : L.28501 : 120 : 150 ,(97 : 3) . L,28552 ; 80 100 : : L.28507 : ~ 5 ~ 5 ; L,28590 . ~ 5 . ~ 5 : : L.28599 : ~5 : ~ 5 : Water / Saccharose : L.28504 : 100 : 110 . (90 : 10) L,28507 ~ 5 ' ~ 5 .

Water/NaCl/CH3COOHL.28504 ; 110 120 :(98,5 : 0.5 : 1): L,28507 : ~ 5 : ~ 5 .
:Water/citric: L.28504 : 110 : 130 ,acid (98 ; 2)L,28507 ~ 5 ~ 5 Water/ CH3COOH L.28504 90 120 (97 : 3) : L.28507 ~5 ~ 5 :Water/ CH3COOH: L.28504 : 120 : 140 (90 : 10) L,28507 ~ 5 ~ 5 .
.Water/ C2~sOHL.28504 150 . 180 :(85 : 15) : L.28507 : ~5 : C 5 :Water/ CH3COOH: L.28504 : 150 : 200 (50 : 50) L.28507 25 .Water/ C2HsO~L.28504 250 _ :(50 : 50) : L.28507 : 50 The p~ of this solution is adjusted to 5 with aqueous caùstic ~oda solution.
: : Stabiliser :
: 0~3 p.c.r. : after 36 h, : after 84 h.
:Heptane : L,28504 : 300 : 390 L,28507 120 ~ 150 ` -26- ~0~6 It is apparent from the8e result~ that the dihydropyridines (I) in which R compri~es from 9 to 22 carbon atoms, and especially those in which R comprises 12, 14 and 18 carbon atoms, give a migration smaller than 5 ~g/l of solution in respect of the solutions a, b, c, d, e, f and g. Under the same conditions, the first terms of the dihydropyridine series (I) and particularly that of which the radical R = -CH3, give migrations of the order of 80 to 100 ~g/l, which are comparable with those of 2-phenyl indole.
For the solutions h, i and j, the dihydropyridines (I) in which R comprises from 9 to 22 carbon atoms, likewise give better results than their lower homologues and 2-phenyl indole.
2.3. - Study of the sublimation ~ he sublimation of the stabiliser is to be taken into account within the sphere of protecting the health of the personnel of the factories where the stabiliser is manufactured or used.
In other words, it is a question in~olving the safety at work.
In this respect, it has been confirmed that :
. the sublimation of the 1,4-dihydropyridines is not only related to the molecular weight. It has in fact been observed that, contrary to what might be expected, the derivati~e (I) for which R = -CX3 is sublimed appreciably less than ~he dih~dropyridines (I) ha~ing a heavier radical R, ~uch as ethyl, propyl, isopropyl, butyl, etc...
Thus, under the operating conditions reserYed for judging the sublimation of the products of this series, the 2-phenyl indole chosen as reference molecule is sublimed at the rate of 62~ of the quantity of product being u~ed. Under the same conditions, the 10947~

derivative (I), for which R = -C~ (methyl), is sublimed to 34%
and the higher homologues, (ethyl, propyl, isopropyl, butyl etc...) to a higher percentage which is bet-~een 35 and 98%.
. The sublimation is important for the values of R representing 1 to 8 carbon atoms, whether these radicals are saturated or unsatu-rated, straight-chain or branched-chain radicals. Under the wor~ing conditions later described, the quantity of sublimed ~roduct is between 10 and 98~. It i~ lowered to 7% for R = straight-chain octyl, and this still represents a considerable sublimation.
. The sublimation becomes small, i.e. equal to or lower than 3~, starting with the radical having 9 carbon atOmS and more particularly starting from the radical comprising 10 carbon atoms.
. The sublimation of the dihydropyridines (I) ha~ing a radical R
which comprises from 10 to 22 carbon atoms is very s~all (in all cases less than 2%), and sometimes even zero, for the saturated straight-chain radicals comprising 12, ~4, 16, ~8, 22 carbon atoms and for the straight-chain and unsaturated radicals, such as the oleylic chain. These findings are valid for mixtures of these different dihydropyridines (example R = oleocetyl radical).
The sublimation of the dihydropyridines (I) having a radical R which is derived from synthesised alcohols aYailable on the market, such as Acropole 35, Dobanol 23, Do~nol 25 ~straight-chain or branched-chain synthesis alcohols comprising from 12 to 15 carbon atoms) remains small ~2 to 3%3 but higher thAn that of the straight-chain radicals, These synthesis alcohols do in ~act contain a large part -28_ of branched alcohols in the a-pohition, since they are prepared by oxo reaction on straight-chain olefines.
It is clearly seen from this last finding that the problem of the sublimation is not connected only with the molecular weight of the dihydropyridine (I) under consideration, but also its structure.
In particular, with equal or comparable molecular weights, a straight-chain radical ~ seems to lead to a smaller sublimation than a branched-chain radical R.
The calculated data which justify these observations are set out below, Sublimation resu~ts 2.3.1 - Operating ~rocedure :
A test sample of about 1~0 mg of the product to be investigated i8 introduced into a 100 cc beaker. The latter is placed in a 250 cc reactor. The temperature is kept at 160C by means of a thermostatically controlled oil bath for 6 hour6, the atmosphere of the reactor being inert (nitrogen~ in order to avoid the oxidation of the 1,4-dihydro-pyridine into pyridine, which is more sublimable.
2.3.2 - Results :
For each dihydropyridine derivative which is investigated, the result is expressed as a percentage of sublimed product relatively to the ~uantity being used.

10~
-2~-: ~ of sublimed Product product :
2-Phenyl indole 62%
: CH3 . 34.2%
-C2H5 ~ 82.9%
~ -n-C3-H7 79,1%

-CH . 98.1X
~ CH3 Dihydropyridines of -(CH2)3-CH3 , 39.2 formula (I) with -(CH2)7 CH3 7 . 2~
R ~ignifying -(CH2)9-C~3 1.7~o _ ( CH2 ) ,~ ,~ - CH3 . 1 . 7%

~ _(CH2)l3~cH3 ~ ; 0.1~
-(CH2)17-CH3 1,2%
-(CH2)21-CH3 0.4 . CH3-(CH2)~- 3.1 : n - 11 to 12 CH3-(CH2)n~ 3.1%
. n = 11 to 14 C12H2s to C15H31 3.2~
: ~CH3(CE2)7~CH=c~~(cH2)n- 1,7%

3(CH2)15- n = 6 to 8 prepared fro~ Dobanol 23 prepared from Dobanol 2~
prepared from Acropole 35 prepared from H.~. Occnol 109"'726 3o-2.4. - Investigation of the photostabilising ~ower A comparati~e study of the photostabilising power of the compounds of the invention was carried out by sheets of polyvinyl chloride, which only differ from one another by the stabiliser which i6 used, being exposed to the sun.
The two re~erence stabilisers were :
- 2-t3'-methoxy-4'-hydroxyphenyl)-indole (S.3630) - 2-phenyl indole (S 3621) Two compositions of polyvinyl chloride were prepared in accordance with the following formula :
Ingredients Part6 by weight Polyvinyl chloride resin 100 Anti-~hock resin 8 Epoxidised soya oil 4 Acrylic resin 0.5 Trinonyl phenyl phosphite 0.3 SL 2016 0.25 Calcium behenate 0.4 Hydrogenated castDr oil 0.2 Glycer~l trimontanate .4 Stabiliser 0.2 The 6tabilised polyvinyl chloride shee~s were prepared by mix~ng on a cylinder at 160C Rnd were expo~ed to the sun under the same conditions.
Their colouring was eYaluat~d in two different ways, after 6 hours and 12 hours exposure to the sun :
- on the ~heet6 themselves, by comparison with the Gardner Scale~ described in French Patent No. 2,27~,841, - on a solution of thefie sheets in tetrahydrofuran by comparison with the sc~le de6cribed in Pharmacopée franc,aiso (9th Edition, II, 3~8).

The reRults obtained are set out in the following table :

: : Colour of the sheets : Colour of the sheet6 Stabilisers : according to GARDNER : according to the P~armacopé
Expo~ure time Exposure time : : 0 : 6 h :12 h : 0 : 6 h : 12 h : S.3630 : 1 : 4 : 8 : B5 :B4 to J~4:~3 to JB3 . S.3621 ; 2 , 3 6 J~J5 J4 : L.28504 : 1 : 1 : 1.5 : JV6: JV6 JV6 L.28501 1 1 1.5 JV6JV6 JV6 .
Four other molecule6 were te~ted ~ R = n-C10~22 (L.28591~;
n-C12R25 (L-28507) ; -C14H29 ~L.285go) ; -C1gH37 (L.2859~)] by comparison with the molecules studied above (R = -CH3 ; R = -C2~5) with the as~istance of the same formula and with 0.2 p.c.r. of ~tabiliser.
The development of the coloration of the s~abilised PVC was judged in the ~ame manner.
The results ac observed show a comparable photostabilising power between these different dihydropyridines, whatever the molecular weight.
Similar tests ware carried out on various formulae of copolymer~.

Comparison of the dihydropyridines according to the inYention (abbreviation D~P) with 2-phenyl indole.
Flexible vinyl copolymer formula vinyl chloride-Yinyl acetate copolymer.

~ormula : Lucovyl SA 6001 100 parts Dioctyl phthalate40 part~
Calcium stearate2 parts Melamine 2 parts Wax ~ 1 part Stabiliser 0.3 part.

: : Time in hours : Coloration in de~rees Gardner :Test :
: :5tabiliser ~ : at time 0 : after 24 hour6 -- . :
; : 2-Phenyl indole : 1 : 6 L. 28504 1 1 ; ; L.28591 : 1 : 1 A ; L.28541 . 1 4 : L.28599 L.28601 : L.28602 :: 2-Phenyl indole : 1 : 8 L.28507 ~ 1 : B: L.28502 : 1 : 1 ~.28506 1 2 :: L.28508 : 1 : 2 EXAMPLE 7 : comparison cf the DHP with 2-phenyl indole rigid vinyl copolymer formula vinyl chloride-viny~idene c~loride copolymer Formula : Re6in Solvic 223 90 parts Copolymer IXAN S~A 1 10 parts ~einforcing agent BTA III 8 parts ~;pDxidised soya oil 4 parts Calcium fitearate 0.2 part Zinc stearate 0.1 part Lubricant 4146 1 2 part Lu~ricant 6164 0.4 part Stabiliser .3 part ~ _ .. __, _ .. . .. ... _ 3~'- ~~ ' ~~5~~ ~~

The lubricant 4146 i~ a hydrogenated castor oil and the lubrica~t 6164 i~ glyceryl trimontanate.

Time in hour~ : Coloration in degrees Gardner ~ :
:Stabiliser ~ at time 0: after 120 hour6:
:
: 2-Phenyl indole : 1.5 : 17 L.28504 1.5 4 : L.28507 : 1,5 : 4 XAMPLE 8 : comparison of the DHP with 2-phenyl indole rigid Yinyl copolymer formula ~inyl chloride-vinylidene chloride copolymer.
Formula : PVC resin Sol~ic 2239 part~
Copolymer IXAN SGA/110 part~
Reinforcing agent BTA III 8 parts Epoxidised 60ya oil4 parts ~alcium 6tearate 0.2 part Zinc stearate 0.1 part Lubricant 4146 1.2 part Lubricant 6164 0.4 part Stabiliser .3 part Time in hours : Coloration in degrees Gardner ~ :~:
:. . : at time 0: after 24 hour~ :
Stab~llcer : 2-Phenyl indole : 1 : 13 L,28597 1 ~ 2 : ~.28601 1 2 L.28541 ; 1 3 .
XA~PL~ 9 : compari~on of the D~P with 2-phenyl indole rigid Yinyl copolymer formula ~inyl chloride-vinylidene chloride copolymer Formula : identical with that of Example 8, but with a variable concentration x of stabili~er, : Time in hours : Concen- : Coloration in degrees Gardner : ~~~___ : tration : . ~~~~-__ : x : at time 0 : after 24 hours Stabillser : 2-Phenyl indole : .3 part 1 : 13 . L.28504 0.3 " 1 . 2 : ~.28507 : O.3 ": 1 : 2 -- -- ------------___I___________~_________________~__________________ L.28504 0.15 " ~ 2 ________________________________________________________________________ : L.28507 : O.7 ~ : 1 : 2 The results of ~xample 9 prove, with the ~ariations in concentration of the products L.28504 and L.28507, that the copolymers in which they are incorporated are stable to light. In effect, variations in concen-tration from 0.15 to 0.7 p.c.r. do not seem to have any influ~ce on the resistance of the copolymer6 to light.
2.5 - Study of the thermostabilising power 2.5.1 - Static ther~ostability The 6tatic thermostability was inYestigated by the ~ethod described in ~rench Patent N 2,27~,841, 2-phenyl indole being the reference substance, The stabiliser is incorporated, with other usual ~dditi~es, into a polyvinyl chloride resin in powder form. A rigid sheet is formed by the mixture being calendered at 160C and this sheet is placed for periods of ~ariable duration in a fixed temperature o~en (1~5C or 2~0CC) until carbonisation commences.
The colouring of the samples is then compared with the Gardner Colour 6cale.

Investigation was carried out with the following resins :

.. . .

In~redientsParts by weight Polyvinyl chloride 100 Anti-shock re~in 9 Epoxidised soya oil 2 Calcium 2-hydroxy stearate 0.2 SL 2016 0.1 Stabiliser 0.3 or 1.55 x 10-3 mole The following results were obtained after ~ resin containing 0.3 part of stabiliser had been in an oven at 210C.

Time in minutes : Stabiliser : : : : : : :
: : 0 : 3 : 6 : 9 :12 : 15 : 18 L.28501 1 1 2 2 4 8.5 B
L.28506 1 1 2 5 11 ' 19 ' B
: L.28507 : 1 : 1 : 2 : 6 : o : 19 : B
L.28508 : 1 : 1 : 3 : 5 :14 B
: L.28509 ~ 2 : 4 : 4 : 17 : B
L.28510 : 1 : 1 : 4 : 5 :15 : B
: L.28504 1 ~ 1 : 2 : 3 :7.5 : 19 : B
2-Phenyl indole : 1 : 2 : 2 : 10: 11 : 16 : B
L.28504 1 1 1 3 7 B
. 2-Phenyl indole 1 1 2 4 13 17 B
-- -- :
; L.28538 1 1 3 3 4 14 B
L.28541 1 1 1.5 3 5 11 B
: L.28504 1 1 1 2.5 3 11 B
2-Phe~yl indole 1 2 2 3 6 14 B
L.28552 1 1 2 4 11 12 B
L.28504 1 1 2 3 8 10 B
2-Phenyl indole . 1 1 2 6 14 14 B
.

~ 0 9 4 ~

The above result~ show the clear superiority of the dihydropy-ridines according to the invention as compared with 2-phenyl indole.
Tests were also carried out at 1850C, with a resin containing 0.3 part of st~bili~er, and the results obtAined are set out in the table below :

Time in minutes : Stabiliser : : 0 : 6 : 12 : 18 : 24 : 27: 30 : 33 : 36 : 39 : 42 : L.28501 1 1 2 8 11 13 13 18 B
. L.28531 1 1 3 7 10 10 10 16 B
: L.28538 1 1 3 10 13 13 14 17 17 B
. L.28504 1 1 2 7 11 11 11 13 B
: 2-Phenyl indole 1 1 3 5 13 13 14 14 15 15 B
.

L.28506 1 1 3 3 6 12 13 14 1515 17 . L.28508 1 1 3 5 8 13 16 18 1818 1&
; L.28509 1 1 2 3 5 9 9 11 1314 15 L.28510 1 1 2 4 10 18 18 19 19 B
; L.28504 1 1 1 2 4 7 7 8 1011 15 2-Phenyl indole 1 1 3 510.5 13 14 1414 14 14 -L.28507 1 2 2 7 11 13 14 15 1518 B
L.28504 1 1 23 5 7.5 8.59 14 B
2-Phenyl indole 1 1 4 9 13 14 14 1414 15 15 .
. L.28502 1 1 2 3 4 6 7 8.5 911 15 ; L.28504 1 1 2 3 4 7 7 8 911 14 2-Phenyl indole 1 1 ; 3 9.5 11 14 1414 14 14 14 ~ ~ . , h ~ V '~. ~

-37- ~,og~7Z6 The above results al60 show the obvious superiority of the dihydropyridines according to the invention over 2-phenyl indole.
Tests were also carried out at 1850C with resins containing equimolecular quantities of stabiliser, namely 1.55 x 10 3 mole, and the following results were obtained:

Weight . Time in minutes Stabili- of stabi-ser .liser . 0 6 . 12 1824 27 30 33 36 39 42 L.28501 0.4 1 1 1 5 10 11; B
L.28531 : 0.5 : 1 : 1 : 2 : 5 :8.5 :10.5~ 16 : B:
L.28538 o.6 1 1 2 7 7 9 10 17 B
L.28541 : o.6 : 1 : 1 : 2 : 7 : 9 : 9 : 10 : 16 : B:
L.28504 0.~5 1 1 1 4 5 8 11 ; 15 B
:2-Phenyl-:0.3 : 1 : 2 : 3 :10 : 13 : 13 : 13 : 14 : 16: 16 : B
indole : : : : :
_ The superiority of the dihydropyridines over 2-phenyl indole is al80 cos~firmed when they are used in the 6ame molecular quahtity as this latter.

Similar test~ were carried out on derivatives of dihydropyridines of which the chain R comprises more carbon atoms.
The following formula was used:

. PVC resin ~Solvic 223) 100 parts . Anti-shock resin 9 parts poxidised soya oil 2 parts SL 2016 0.1 part SS 32 0.2 part . Stabiliser x (x = 0,1 to 0.3 p.c.r.) The product SS 32 is calcium hydroxystearate.
Use was made of t~le experimental methods described above for r - '~ 7 ' -' --38_ ~0!3~;~qZ6 obtaining the stability bands and their examination, by employing the evidence of stability at 210C in an oven.
With equal quantities, the various dihydropyridines (I) give co~nparable results, whatever the value of the radical R. The fact of increasing the molecular weight of (I) does not lower its thermosta-bilising power and concentrations which vary from 0.01 to 0.5 p.c.r.
and especially from 0.01 to 0.2 p.c.r. lead to very good results.
The results as obtained are set out below.
Quantity of stabiliser in the formula : 0.3 p.c.r.

Time in minutes . 0 ; 3 . 6 9 . 12 . 15 Stabiliser ~

L.28597 ~ 2 : 4 : 7 L.28598 1 1 1 2 4 13 L.28596 ~ 1 : 2 : 4 : 13 :_ _ :L.28600 : 1 : 1 : 1 : 2 : 5 : 13 2-Phenyl indole 1 1 2 4 11 14 ~ime in minutes : O : 3 : 6 : 9 : 12 ~ : : : : : :
Stab--liser ~
L.28601 , 1 1 2 , 2 , 4 L.28507 , 1 1 2 2 3 2-Phenyl indole 1 , 1 2 4 ; 10 ~ . . _. . "; _ . .

~094726 Quantity of stabiliser in the formula : 0.2 p.c.r.

0 . 2 . 4 : 6 : 8 : 10 : 12 : 14 :
: Stabiliser ~
L.28597 . 1 1 1 2 3 3 . 11 . 11 .
L.28598 1 1 1 2 3 3 11 15 .
.28596 1 1 1 2 , 3 3 ; 11 . 13 .
L.28599 1 < 2 <2 , 2 3 3 10-5 14 ;

=~.

~ :
me in minutes . 0 2 ; 4: 6 : 8 : 10 : 12 :
Stabiliser ~

L.28590 . 1 1 1 2 , 2 3 7 L.28591 1 1 1 2 , 2 3 8 2-Phenyl indole 1 1 1 2 2 ; 5 ; 9 Quantity of 6tabiliser in the formula : 0.1 p.c.r.

in ~inutes o 2 : 4 : 6 : 8 : 10 : 12 :
~.

L.28591 2 2 2 2 2 4 10.5 L.28507 2 2 2 2 3 , 4 .10.5 ~_` ' J

,10~47Z6 5.2 - Stabilisation of the resins intended for the bottling of mineral waters.
The tests were carried out in the following manner :
- a resin which contains calcium stearate, zinc stearate and epoxidised soya oil in addition to the stabiliser which is to be tested was mixed on a cylinder-type mixer and the stability of the initial colour was noted, that is to say, the time elapsing between the commencement of the mixing and the first visible change in the colour of the resin was measured. The thermal stability of the resin was also observed, i.e. the time elapsing between the commencement of the mixing and the degradation of the resin was measured, - a like resin was passed through an extrusion and blowing machine and the development of the colour of the resin was observed at each of the three passages through the machine.
For this extrusion-blowing operation, the following characteris-tics were retained :
Temperature : 165 - 160 - 165 - 160 - 180C
Screw speed : 60 r.p.m.
Die : gap : 1.5 mm, land : 55 mm Mould : cylindrical bottle of 250 cc.
Four resins, numbered from 1 to 4 and respectively containing 0.2 part of 2-phenyl indole, 0.2 ~ 0.03 and 0.0~5 part of the compound L.28~04, were te~ted and the following results were obtained :

109~726 . .

Resin ;Mixing at 220C . 1 : 2 3 4 Colour stability 3 . 6 3 2 .in minutes :Thermal stability : 13 : 13.5 : 12.7 : 12.3 :in minutes Bottle colour at Sky blue Bright Bright . Bri~ht .1st passage . sky blue sky blue sky blue 2nd passage Blue, Bright Bright Bright toning sky blue sky blue sky blue towards . green 3rd pas6age . Greenifih ; Bright . Bright ; Bright : : blue : sky blue : sky blue : sky blue It can be confirmed that 2,6-dimethyl-3,5-dicarbomethoxy-1,4-dihydro-pyridine imparts t~ the resin a colour stability which is more marked than that of 2-phenyl indole, even at a rate of 0.015 part per cent of parts of resin.
The same tests are carried out, but with a resin containing different proportions of zinc and calcium stearate.

Stabiliser ~ Quantity of stabiliser _ / N of resin 1 2 3 4 :
Calcium stearat~ 0.29 0.29 0.29 0.29 .O.Z9 0.29 0.29 0.29 Ø15 2-Phenyl indole 0.15 L.28504 - 0.15 0.075 0,05 0.03 0.015. 0.15 0.15 0.07 _ ~, t~

109^1726 The following results were obtained :

._ Resin Mixing at 220C . . . . . A

Colour stability ; 2to . 5 ; 4 ~ 4 3 . 3 . 3 . ~ 1 . 3 ;in minutes 3 Heat stability. ~ 9 8.5 8-5 8.5 . 8.5 .15.5 ~ 7 5 in minutes As in the preceding test, the compound LA28504 improves the co~-our and the stability. Compound L.28504 has proved to be 10 to 15 times more efficient than 2~phenyl indole.
In formula N 2, the compound L.28504 does not have any direct influence on the heat stability, but it permits, while preserving the colour shade, of reducin6 the amount of zinc stearate, which may cause the appearance of defects in the resin.
As regards the examination of the colouring of the resin after each passage through the extruder and blowing machine, the excellent behaviour of the resins containing compound L.28504 has been confirmed.
2.5.3 - Stabilisation of the ~lasticised resins Sheets of polyvinyl chloride, previously mixed for 5 minutes at 180C, were pressed for 5 minutes at 170C, and the colour stability and the heat stability after mixing, and then the coloration of the sheets after pressing, were obser~ed.
As adjuvants, as well as the stabiliser to be tested, the resin in question contains wax ~, dioctyl phthalate, barium stearate and cadmium stearate, in the followinF proport ions :

43 . '10947Z6 Ingredients Quantities :
of resin 1 2 3 4 5 6 7 & . 9 Polyvinyl chloride 100 ' 100 100 100 100 100 100 100 10C
resin :E wax: 0.3 : 0.3 : 0.3 : .~ : ~3 :~3 : ~3: ~3 : ~3 ,Dioctyl phthalate 50 . 50 , 50 50 50 . 5 . 5 . 5 5 .Barium stearate ~ - :0.375: - :0.375:.375 :.375 :0~375 :-~75 :~375 .Cadmium stearate - - 0.375 '375 '375 0.15 0.15 0.05 ~5 Compound: - : - : - : - : 0.1 : - : 0.05 : - : 0.0 The followin~ results were obtained :

-Colour stability . in minutes . 25 25 . 25 . 35 . 50 30 45 . 20 , 35 :Thermal stability : in minutes 25 5 25 . 35 . 5 3 i 55 25 50 Pressing at 170C

Colour 6hade of - - -Pink- Very Pink~ Very 'Red- Yell the pressed sheet . . ish sligh- sl-gh- dish wish .(thickness : 3mm) . ; , . yello- yello-.
wish wish The above results show that the compound L.28~04 substantially impro~es the basic shade and clearly increases the thermal stability.
It is also established that the presence of the compound L.28504 permits a reductio~ in the proportion of cadmium stearate, which is a ~ery costly and toxic product.
Finally, the thermal or heat ctabilisation of the vinyl copolymers by the dihydropyridines was inYestigated.

~0~726 -44_ EXAMPLE 11 : rigid copolymer formula vinyl chloride-vinyl acetate copolymer Formula : Lucovyl MA 6035 80 parts Lucovyl MB 1000 20 parts Calcium stearate 0.5 part Stabiliser 0.3 part Exa~ination of the stability in a ventilated oven at 185~C.

~ ~ in minutes , 0 2 : 4 : 6 : 8 : 10 : ~2 Stabiliser ~ : : : : : :
No Stabiliser 1 2 ; 4 7 1~ 16 , 17 . 18 L.28599 1 1 3 6 10 14 16 . 17 , .~ ~.

L.28602 1 1 4 9 12 16 ' 17 18 :
L.28502 1 , 1 3 6 10 13 14 18 Comment : The colorations expresse~ in degrees Gardner are favourable a6 regards the formulae stabilised by the dihydropyridines according to the invention. However, in actual fact, the figures only inadequately show the spacings, because the copolymer which is not stabilised shows a relatively intense colour formation from the zero time~ which it is difficult to indicate in the ~ardner 6cale.
EXAMPLæ 12 : rigid copolymer formula .
vinyl chloride-vinyl acetate copolymer Formula : ~ucoYyl MA 6035 80 parts Lucovyl-MB lU00 Z0 part6 Calcium 6tearate 0 5 part Stabili&er 0.1 part Exa~ination of the sta~ility in a ventilate~ oven at 1&5C.

_45_ 1094726 ~Time in minutes ~ 0 2 4 6 8 10 12 14 : Stabilise~; : : : : : : : : :
No Stabiliser 1.5 2 4 11.5 15 1? 18 18.5 L.28504 : 1 : 1 : 4 : 6 :11 :11 : 12 : 13 L.28507 1 1 4 10 12 13 15 L.28597- ; 1 : 1 : 4 : 10 :12 :15 : 17 The comment made in connection with Example 11 is also applicable.

EXAMPLE 13: flexible copolymer ~ormula vinyl chloride-~linyl acetate copolymer Formula : Lucovyl MA 6035 100 parts Dioctyl phthalate 60 parts Melamine 2 parts Calcium stearate 2 parts Stabiliser 0.2 part Gelling : 5 -minutes at 120C.
Pa6sage through a Metrastat o~en at 160~C : time 60 minutes rate of flow 50 l/hour.

: : : : : :
minutes : O : 30 :40 : 50 : 60 :
Stabiliser ~: : : : : :
Without stabiliser 1 6 13 14 , 17 .
L.28504 : 1: 1: 2: 4 : 12 .
~.28507 , 1 2 6; 12 . 15 EXAMPLE 14: flexible copolymer forn~ula ~inyl chlclride-vinyl acetate copolymer ~ormula : Luco~,ryl SR 6001 100 parts Dioctyl phthalate 40 parts Calc~um stearate 2 parts Melamine 2 parts Stabiliser 0.3 part " ~

109~t726 Passage through a Metrastat oven at 1600C : time 60 minutes rate of flow 50 l/hour.

Time in minutes ~~~~~~--- O 10 20 3~ 40 50 60 : Stabiliser -~~~--___ : : : : : : : :
Without stabiliser , 1 . 1 5 8 12 . 13 . 13 L.28504 1 1 2 6 8 , 10 . 12 L.28507 1 1 2 6 8 10 12 .

EXAMPLE 15 : rigid copolymer formula vinyl chloride-~inylidene chloride copolymer Formula : Sol~ic 223 90 parts .
IXAN SGA/1 10 parts Reinforcing agent BTA III 8 parts Lpoxidised soya oil 4 parts Calcium stearate 0.2 part Zinc stearate 0.1 part Lubricant 4146 1.2 part Lubricant 6164 0.4 part Stabili6er 0.3 part Passage through a ~entilated oven at 210C

.
: : : : :
~ n minute8 o ; 3 : 6 : 9 : 12 : 5 Without 6tabil'iser 2 , 2 , 5 10.5 ; 14 , 16 .
L 28504 1.5 1.5 2 ~ 10 13 ~
.
~.28507 1.5 1.5 , 3 , 4 12.5 ~5 .

The comment made with respect to Example ~'~ 1 is also applica~le.

EXAMPE~ 16 : rigid copolymer formula ~inyl chloride-~inylidene chloride copolymer 1~)9~1726 Formula : Solvic 223 90 p~rts IXAN SGA/1 10 parts Relnforcing agent BTA III 8 parts Epoxidised ~oya oil 4 parts Calcium stearate ^ 0.2 part Zinc ~tearate 0.1 part Lubricant 4146 1.2 part Lubricant 6164 0.4 part Stabiliser 0.3 part Passage through ventilated oven at 210C.

' minutes 0 . 3 ; 6 . 9 . 12 : Stabiliser -~~~--____ : : : : ; :
, Without stabiliser ~ 1.5 2.5 4.5 11 14 L.20597 1 1 2 4 12.5 .
L.28601 1 1 2 5 13.5 .

The comment made with respect to Example 11 is a~so applicable.
The dihydropyridines of formula I (DHP) were compared with the ~aminocrotonates of alcohols and of polyols.
The following Examples 17 to 29 show the superiorit~ of the thermo6tabilising power of the 1,4-dihydropyridines of formula (I) o~er that of the ~-aminocrotonates.

XAMP~ 17 : comparison of the D~P with the butane-1~4-diol-~-aminocrotonate and the methyl ~-aminocrotonate.
Rigid copolymer formula vinyl chlori~e-vinyl acetate copolymer Eormula : Lucovyl MA 60~5 80 parts Lucovyl M~ ~000 20 parts Calcium ~tearate 0.5 part Stabiliser 0.5 part Passage through ~entilatec oven at 185~C.

~ minute~ . 0 . 2 . 4 . 6 : Stabiliser Butane-1,4-diol-~- . 1 . 1 4 . 10 . 13 15 . 18 aminocrotonate Methyl ~-aminocro- 1 1 5 12 14 17 . 18 ; tonate L.28504 1 1 . 1 5 8 11.5 , 13.5 EXAMPLE 18 : comparison of the DHP compounds with the stabiliser G1 (stabiliser G1 is a mixture at present in use and con~is-ting of butane-1,4-diol-bis-~-aminocrotonate and of C16-C18 alcohol ~-aminocrotonates).
Rigid vinyl copolymer formula vinyl chloride-vinyl acetate copolymer Formula : Resin, Solvic 547 S.A. 80 part6 Resin, Lacqvyl S-071-S 20 parts Calcium stearate 0.5 part Irgawax 280 0.1 part Stabiliser 0.3 part Passage in a ventilated oven at 1850C.

~ in minutes .Quantity of . o 2 4 6 : 8 : 10 : 12 14 : Stabiliser ~ : Stabiliser : : : : : : : .
~;
L.28504 , 0.3 part 1 1 1 2 3 . 4 , 7 13 .
L.28507 0.3 part 1 1 1 2.5 4 7 10.5 . 17 XAMPLE 19 : comparison of the D~P compound6 with the stabiliser G
rigid vinyl copolymer formula vinyl chloride-vinyl acetate copolymer 49 ` ~og47;~6 `

Formula : Lucovyl MA 6035 oO parts Luco~yl MB 1000 20 parts Calcium stearate 0.5 part Stabili6er G1 or DHP 0.5 part Pas6age in ventilated oven at 1850C.

~ n minutes , 0 . 2 4 6 . 8 . 10 12 :Stabili~er ~ : : : : : : : :
. Stabiliser G1 . 1 1 4 11 12.5 16 , 18.5 , L.28504 , 1 , 1 1.5 6 9.5 13 17 XAMPLE 20 : comparison of the DHP compounds with the stabiliser G1 rigid ~inyl copolymer formula vinyl chloride-~inyl acetate copolymer.
Formula Lucovyl MA 6035 80 parts Lucovyl MB 1000 20 parts Calcium stearate 0.5 part Stabili6er G1 or D~P 0.5 part Passage in ~entilated o~en at 185C

Time in minutes , - ~~~~~-- 0 2 4 ; 6 8 10 12 : Stabiliser ~~~--__ : : : : : : -Stabiliser G~ , 1 . 1. 2.5 11 13.5 . 17 18.5 ;
L.28597 1 , 1, 2 3 11 , 13 .
L 2c599 ~ 1 12-5 ~ 11 15 L.28601 , 1 , 1 ~ . 6 , 13 17 EXAMPLE 21 : comparison of the DHP compounds with ~e stabiliser G1 rigid Yinyl copolymer formula ~inyl chloride-vinyl acetste copolymer.

. ~094726 Formula : Vinnol H 13/50 S 100 parts Glyceryl tribehenate 0.4 part Calcium ~tearate 0.5 part G1 or DHP stabiliser 0.5 part stability in a ventilated oven at 1850C.

-~ n minutes , 0 2 4 6 8 10 ~ 12 14 : Stabiliser : : : : : : : : :
S~abiliser G1 . 1 . 2 3 4 9 . 12 , 18 L.28504 , 1 l 2 3 4 , 11 18 -XAMPLE 22 : comparison of the DHP compounds with stabiliser G1 rigid vinyl copolymer formula vinyl chloride-vinyl acetate copolymer.
Formula : Lucovyl Mb 6035 80 parts Lucovyl MB 1000 20 parts Calcium stearate 0.5 part DHP or G1 stabiliser 0.3 part Stability in ventilated oven at 1850C

Ti~e in minutes ~~~~~~~-- O 2 4 6 8 10 12 14 : ~.
Stabiliser G1 . 1 , 1 , 2 3 , 6 , 10 12.5 16 .

~.28504 , 1 , 1 , 2 3 4 ; 6 , 9 , 13 ; L.28507 ; 1 , 1 2 4 5 ; 9 , 10 . _ L.28597 ; 1 , 1 2 3 5 ; 8 11 ~XAMPLE 23 : comparison of the DHP compounds with stabiliser G1 rigid Yinyl copolymer formula ~inyl chloride-~i~yl acetate copolymer.

' -51- ~ 0 9 ~ ~

Formula : Lucovyl MA 6035 80 parts Lucovyl MB 1000 20 parts Calcium stearate 0.5 part DHP or G1 stabiliser 0.1 part St~bility in ventilated oven at 1850C.

Time in minutes' ' , , ~ ~ 0 2 4 6 8 10 12 14 : Stabiliser ~~~--___ : : : : : : :
Stabiliser G~ 1 1 6 711 1214 . 16 .
L.28599 1 . 1 4 , 6; 10 . 1112.5 - .
.
L.28601 1 1 4 6 10 11 13 . - .

L.28501 1 1 2 4 10 11 14 , _ .

. L.28506 . 1 , 1 2 6 . 10 12 14 XAMPLE 24 ; comparison of the DHP compounds with the stabiliser G
rigid vinyl copolymer formula vinyl c~loride-vinyl acetate copolymer Formula : Luco~yl MA 6035 80 parts Lucovyl MB 1000 20 parts Calcium stearate 0.5 part DHP or G1 stabiliser 0.3 part Stability in ventilated oven at 1850C

Time in minutes ~~~~~--- 0 2 4 68 10 12 14 . Stabiliser G1 1 ' ~ 2 ;6 11.5 1618 ~urnt , , L.20541 . 1 ~ 2 , 510 1~ 13 16 ;

~XAMPL~ 2~ : compari60n of the DHP compounds with the stabiliser G1 rigid vinyl copolymer formu}R
vinyl chloride-vinyl acetate copolymer .
., , . . ---~

~0~172.fi Formula : Lucovyl MA 6035 80 parts Lucovyl MB 1000 20 part6 Calcium stearate 0.5 part Stabiliser 0.1 part Stability in ventilated oven at 1850C.

Time in minutes ~~~~~-- O ' 2 4 68 10 12 : Stabiliser ~~~--_~
. Stabiliser G1 . 1 , 1 ~ 2 6, 13. 16 . 18 , ; L.28541 . 1 1 2 ; 412 13 17 EXAMPLE 26 : compari60n of the DHP compounds with 2-phenyl indole rigid vinyl copolymer formula vinyl chloride-vinyl acetate copolymer Formula : Lucovyl MA 6025 80 parts Lucovyl MB 1000 20 parts Calcium stearate 0.5 part Stabiliser 0.3 part Stability in ~entilated o~en at 185C.

Time in minutes ~~~~~--- 0 2 4 6 8 10 12 14 : Stabiliser -~~- : : : : : : : .
2-Phenyl indole 1 1 2 3 8 12 14 . 17 .

L.28504 , 1 1 . 2 . 3 5.5 . 8 . 12 . 15 L,28507 , 1 , 1 . 2 ; 3 , 10 11 ; 16 ,17.5 ~XAMPL~ 27 : comparison of the D~P compounds with 2-phenyl indole rigid ~i~yl copolymer formula vinyl chloride-~inyl acetate copolymer Formula : Luco~yl MA 6035 80 parts Luc o~yl MB 1000 20 part~
Calcium stearate 0 5 part Stabili6er 0.1 part 109~t726 Stability in ventilated oven at 1850C

.
Time in minutes ~ 0 2 4 6 8 10 12 14 : Stabiliser~~~--___ : : : : : : : : :
2-Phenyl indole 1 1 2 ~.5 10.5 13 16 18 -L.28504 1 1 2 3 7 11 ; 13 17 EXAMPLE 28 : comparison of the DHP compounds with 2-phenyl indole rigid vinyl copolymer formula vinyl chloride-vinylidene chloride copolymer Formula : PVC resin, Solvic 223 90 part6 Copolymer IXAN SGA/1 10 parts Reinforcing agent BTA III 8 parts Epoxidised soya oil 4 part~
Calcium stearate 0.2 part Zinc stearate 0.1 part Lubricant 4146 1.2 part Lubric~nt 6164 0.4 part Stabiliser 0.3 part Passage in ventilated oven at 210~C.

Time in minutes 5t ~ 3 6 ; 9 ;12 15 2-Phenyl indole 2 2 5 8.5 14 16 .
L.28504 , 1.51.~ 2 3 10 .28~07 , 1.~ 3 4 12.5 1~

~XAMPL~ 29 : comparison of the D~P compounds with 2-phenyl indole -rigid vinyl copolymer formula vinyl chloride-vinylidene chlori~e copolymer ormu1a : PVC resin, Solvic 223 90 parts Copolymer IXAN SGA/1 10 parts Peinforcing agent BTA III 8 parts ~0947Z6 Epoxidised soya oil 4 parts Calcium stearate 0.2 part Zinc stearate 0.1 part Lubricant 4146 1.2 part Lubricant 6164 0.4 part Stabiliser x part Passage in ventilated oven at 210C.

Time in minutes Quantity ~= --Stabiliser .
, 2-Phenyl indole. 0.3 part 1 1 4 10 15 -L.28597, 0.3 part 1 ; 1 2 4 12.5 ;

L.28601. 0.3 part 1 1 2 . 5 . 14 L.28541 , .3 part . 1 1 , 2 4 o .~
L.28504 0.3 part 1 1 ; ~.5 3.5 5 ' L.2850?' .3 part 1 1 2 5 . 8-5 _______________________________________________________________________ L.28507 0.7 part . 1 1 , 2 5 ; 7 _______________________________________________________________________ : L.28504 : 0.15 part : 1 : 1 : 1.5 : 3.5 : 5.5 The refiults which are set out in the foregoing table show that :
the dihydropyridines of formula (I) may be effective as thermo-stabilisers of the vinyl copolymers with a concentration which is smaller in the formula than the 2-phenyl indole, a concentration of 0.15 p.c.r. of dihydropyridine of formula ~I), and of L.28504 in particular, lea~s to a better result than 0.3 p.c.r. of 2-phenyl indole, the use of certain dihydropyridines of formula (I) instead of 2-phenyl indole may provide an undoubted economic interest, the increase in the quantity of a dihydropyridine of formula ~1), such as L.28507, in the formula improves the stabilisation time ~Og4~Z6 but has practically no influence on the colouring of the copolymer during the first 10 minutes of the heating period.
2.6 - Study of the antioxidant power This study was carried out in two periods :
- it was shown that the dihydropyridines according to the invention had antioxidant properties better than those of the known antioxi-dants, such a~ hydroquinone, 4-methoxy phenol and di-tert.-2,6-butyl-4-methyl phenol, - it was shown that the antioxidant power of the dihydropyridines according to the invention, directly on a vinyl resin, is superior by comparison with an antioxidant very widely used in this field, namely, di-tert.-2,6-butyl-4-methyl phenol.
2.6.1 - Polaro6raphic study of the oxidation potential EXAMPLE ~0 a) Working condition~
Llectrodes - eference electrode : a calomel electrode which contains, as junction liquid, a saturated solution of anhydrous lithium perchlorate wor~ing electrode : rotating electrode of ~itreous carbon (2500 r.p.m.
counter-electrode : platinum.
Chemical products - acetonitrile, ha~ing a water content smaller than 0.1~o and not pre-senting any polarographic waves between -2.5 volts and ~2.5 Yolts.
- anhydrous lithium perchlorate with a water content s~aller than ~.

10!9~17~6 Rea~ents 0.1 M solution of lithium perchlorate in acetonitrile, treated and preserved on a molecular screen of 4 A.
Polarographic conditions voltage : 10 m~
initial potential : OV
exploration amplitude : O to 2V
exploration speed : 10 mV/sec.
sensitiYity : 1.25 ~A to 50 ~A - mean concentration 0.3.10 3 mole/litre.
Precaution Between each measurement, the vitreous carbon electrode and the platinum electrode are carefully cleaned with Joseph paper.
The results given below were obtained :
Products Oxidation potential Compound L.28504 0,74 - 0.01 Compound L.28501 0.73 - 0.01 Di-tert.-2,6-butyl-4-methyl phenol 1.11 - 0.02 Tert.-2-butyl-4-methoxy phenol 0.81 - 0.01 Hydroquinone o.83 - 0.01

4-~ethoxy phenol o.89 - 0.01 The values found show that the dihydropyridi~es according to the invention have a greater reducing power than the reference antioxidant~.
~XAMPLE 31 a) Working conditions ~lectrodes - platinum counter-electrode and calomel electrode with filling by a saturated aqueous solution of lithium chloriae.

_57_ 109~7~
Reagent The measurements were carrieà out in the following solvent :
- 90 parts of a 0.1 M solution of lithium perchlorate in methanol, - 10 parts of a 0.1 M solution of perchloric acid in acetic acid.
Polarographic conditions - square voltage superimposed with constant pulses of + 10 milliYOltS
- initial potential : 500 millivolts, - scanning voltage : 1000 millivolts in the anode direction, - oxidation at the vitreous carbon electrode (speed of rotation :
2000 r.p.m.), - temperature : 35~C.
The definitive results were achieved at the concentration of 0.5 m.mole/litre for the BHT, a dihydropyridine derivative of low molecular weight (L.2O504 : R = methyl) and three heavy dihydropyridine derivatives (L.28507 : R = dodecyl, L.28602 : R = oleyl, L.28590 : R =
myristyl).
b) Results The following table indicates the values AS obtained in millivolts, for the oxidation potential and the nature of the radical R of the corres ponding formula I.

~HT~ 116~ millivolts L.28504' ~ 850 millivolts L.28507+ 78~ milliYolt6 L.28602t 808 milli~olts L.28590 + 732 millivolts The following conclusions are reached from an examination of these result6 : .
- the dihydropyridines (I) have an oxidation potential which i5 clearly smaller than that of the BHT and, as a consequence, more powerful antioxidising properties ;
- the heavy dihydropyridines (I) (L.28507 - L.28590 - L.28602) have an oxidising potential smaller than that of the lightest dihydropyridine (I) (R = -CH3 ; L.28504) and, as a ccnsequence, show better antioxi-dising properties.
2.6.2 - Study of the antioxidising power on a vinyl resin The investigation wa6 carried out with the following resin, which contains, as antioxidising agent, either the compound L.28504 or BHT.
Ingredient6 Parts by weight Polyvinyl chloride resin 100 Anti~hock agent 10 Acrylic resin 0.
Epoxidised 80ya oil 3 SL 2016 0.1 Calcium and zinc stearates 0.2 Hydrogenated castor oil 1.5 Polyethylene wax .3 Antioxidant C.05 to 1 The stability bands were examined :
- in a conventional oven at 1850C, every 10 minutes, for 80 minutes, - a Metrastat oYen at 210~C, for 1 hour.
The coloration was calculated according to the Gardner scale.
The follo~ing results were obtai~ed :

10~7Z6 a) oven at 1850C.

.
Concen- . Antioxy^ Time in minutes trations dant : : :0 10 20 30 40 50 60 70 80 .

0.05 BHT ~ 1 . 1 2 ; 5 > 6 7 7 8 B
L.28504 :1 : 1 : 1 : 3 :4 : 6 : 7 : 8 : B

0~1 . B~T , > 1 . 1 2 > 5 ~ 6 7 7 . 8 B
: : L.28504 :1 : 1 : 1: < 2 : 3 : 5 : 7 : 7 : B

0.2 BHT ~ 1 1+ 2 5 > 6 7 7 8 B
; L.285041 ; 1 ; 1 ; 1 : 2 : 3 : 5: > 6 : B

0.3 BHT~ 1 , 1 > 2 > 6 7 8 8 8 B
: : L.28504 :1 : 1 : 1 : 1 : 2 : > 2 : 8 : 8 : B

' 0.4 ' BHT ~ 1+' ~ 1 3 ~ 6 8 ; 9 9 9 B
: : L.28504 : 1 : 1 : 1 : 1 :1+ : ? 2 . 4 : 8 : B

.5 BHT ~ 1 ~ 1 3 ~ 6 ~ 7 8 ; & 8 B
L.28504 1 ~ 2 : 4 : 8 : B

1 BHT 1 2 > 3 8 8 8 9 9 . B
: : L.28504 : 1 : 1 : 1 : 1 :1 : 4 : & : B

The symbol "B" indicates "burnt", while the index "+" signifies that the colour is disposed half-way between the lower unit and the upper half-unit. Similarly, the index "-" signifies that the colour is between the lower half-unit and the upper unit ~inally, it waB considered, for example, that ~ 2 means that it i6 between 2 and 2 .
It may be concluded from the abo~e results that the compound L.28504 is very clearly better than the reference compound, for ~0 minutes, and for all the antioxidant concentrations.

-60_ 1094~6 b) Metrastat oven at 210C.

Concen- Antioxy- Time in minutes tration dant ; ; ;0 to 10 .10 to 20.20 to 25~25 to 30 30 to 35- 35 to 40 BHT . 2 3 4 ' 10 , >10, B
: 0.05 : : : : : :
: : L.28504 : 1 : 1 : 1 : 1 : 5 : ~10, B
: at 40 ; BHT 2 2 , 3 . 4 . 11 ; ~11, B
: 0.1 : : ; ~
: : L.28504 : 1 : 1 : 1 : 1 : 5 :~ 10, B
: : : at 38 .
BHT . , 2 . 3 4+ . 11 . >11, B
: 0.2 : : L.28504 : 1 : 1 : 1 : 1 : 5 : ~ 9, B
: : at 39 3HT , < 1 2 . 3 . 3 . 9 ~ 10, B
: 0.3 : : : : : : : :
: : L.28504 : 1 : 1 : 1 : 1 : 3 : ~ 6, B
: : : : : : : : at 39 .
. BHT ' 2 2 3 3 . 10 ~1~8B
: 0.4 : : : : : : :
: : L.28504 : 1 : 1 : 1 : 1 : 4 : 6 ; B
: at 38 BHT 2 2 3 ; ; at 30 : 0.5 : : L.28504 : 1 : 1 : 1 : 1 : 3 : 6 , B
: : at 38 BHT 2 2 3 5 11 , > 11 ,8B
t +
: : L.28504 : 1 : 1 : 1 : 1 : 2 : ~ 2 ~ B
: : : : : : : : at 3~ :

The results also show the clear superiority of the compound L.28504 over the reference compound.
It i~ nece66ary to point out that, from the zero time~ the sheets containing the BHT show a pink colouring~ and this represents another disadvantage of the BHT.

`" ~09-~726 -6~--2.7 - Study of the lubricating power The lubricating powe. was judged by the adhesion time, which was determined on a calender-type mixer, equipped with heating cylinder6, and compared with that of a reference stabiliser.

The temperature of the cylinders was from 165-170C and the reference stabiliser was the stabiliser G1.
Formula investi~ated :

Solvic 547 SA 80 parts Lacqvyl S.071/S 20 parts Irgawax 280 0.1 part Calcium ctearate 0.5 part Stabiliser from 0.3 to o.8 part Results :

N of tests , ~ua~tity of stabiliser p.c.r.
:~ ~
: Stabiliser 1 2 3 4 5 6 . 7 L.28504 0.3 L.28507 ' ' o.3 o,7 L.28596 , , 0.3 o.8 .~ '.
Adhe~ion time 12 min 12 min 17 min 12 min 17 min; 12 min.15 ~in .
: .45 sec 30 sec .30 sec.20 sec~ .2~ sec .

These results 6how that :
wi~h equal concentration (0.3 p.c.r.), the dihydrop5~rid~s~es of formula (I) and the stabiliser G~ ha~e a ~ery closely related adhesion time, with an advantage for the dihydropyridines of high mo~ ecular weight (L.28507 and 1.28596), with equimolecular concentration (0.3 p.c.r.) fo~ L.28~04, 0.7 p.c.r.
for L.28507~ o.8 p.c.r. for L.28596), the lubricatin~ power of L.28507 and of L.28596 i5 definitely better than that of L.28504, `` 10947Z6 - disregarding the concentration, the lubricating power of the dihydro-pyridines of formula (I) is at least comparable with that of the sta-biliser G1. It is better as regards L.28507 and L.285g6. It is shown by this comparison that the dihydropyridines may be used in place of the aminocrotonates, for example, for the manufacture of recording disc The temperature of the cylinders was from 180-190C and the reference stabiliser was 2-phenyl indole.
F~rmula investigated - PVC resin (Solvic 223)100 parts - Antishock resin (BTA III)8 parts - Epoxidised soya oil Z parts - Stabiliser x p~rts Workin~ conditicns on the calender-type mixer :
Front cylinder : temperature 190C
Rear cylinder : temperature 1800C.

Products R x (pcr) Adhesion time :
: L.28504 : -CH3 :~5 :12 min. : 17 sec.
:
~ L.28501 . C2 5 , 11 min. ; 25 sec.
: L.28506 : -CH(CH3)2 5 ~8 min. 0 sec.
' 0.527 8 min. .30 sec.
: : : 0.555 :9 min. :0 sec.
L.28502 : -(CH2)7-CH~ : -5 : 12 min. : 19 sec.
, o.665 13 min. 25 ~ec.
: : : o.83 : 15 min. :25 sec.
: L.28591 : -(CH2)9-CH3 : 0.5 ~ 13 min 29 sec.
, 0.72 ;16 min. 10 sec.
: : : 0.94 :~8 min. :30 sec.
: ~.28507 : -(CH2)11-CH3 : ~.5 ' 14 min 36 sec.
-775 ;19 min. 10 sec.
: : : 1.05 :22 min. :45 sec.

109~726 lt becomes apparent from these results that, within the series of dihydropyridine molecules ~I), those of which the radical R contains from 9 to 22 carbon atoms lead to an adhesion time which is decidedly better than that observed in respect of the lower homologues, when they are used in equimolecular quantities or equal quantities. This improve-ment in the adhesion time represents 15 to 50~ of the mean adhesion time of the group of the dihydropyridines, of which the radical R varies between 1 and 8 carbon atoms.
In particular, the 2,6-dimethyl-~,5-dicarbododecyloxy-1,4-dihydropyridine shows a considerable improvement in the aahesion time in all the formulae which have been examined.
These properties are to be emphasised, because they are capable of reducing the expense involved in the stabilisation, by making possi~le a reduction in the amount of lubricants or an impro~ement in the passage of the PVC compound on the machines which carry out the extrusion and the blowing.
The fact of increasing the dimension of the -adical R in the formula (I) thus enables this general structure to be given three interesting properties, which are not possessed b5~ the lower homologues (R ~ C8) of the series, ana this limits the use of these lower homo-logues and extends to the exclusion thereof in the foodstuff field (migration). However, the increase in the molecular weight does not modify the photostabilising and thermostabilising properties of these molecules by comparison with the lower homologues.

Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A synthetic resin composition comprising a vinyl polymer or copolymer and, in an amount sufficient to impart stabilization against degradation by heat and light, a 1,4-dihydropyridine derivative represented by the general formula:

wherein R represents an alkyl radical containing from 1 to 22 carbon atoms, an octadecenyl radical, a cyclohexyl radical, a phenyl radical or a phenyl radical substituted by a halogen atom or methyl or methoxy radical.

2. A composition according to Claim 1, wherein the dihydropyridine derivative is present in an amount of from 0.01 to 0.5 percent by weight, based on the vinyl polymer or copolymer.

3. A composition according to Claim 1, wherein the dihydropyridine derivative is present in an amount less than 0.2 percent by weight, based on the vinyl polymer or copolymer.

4. A composition according to Claims 1, 2 or 3, wherein the vinyl polymer is polyvinyl chloride.

5. A composition according to Claims 1, 2 or 3, wherein the vinyl copolymer is a vinyl chloride-vinyl acetate copolymer.

6. A composition according to Claims 1, 2 or 3, wherein the vinyl copolymer is a vinyl chloride-vinylidene chloride copolymer.

7. A composition according to claims 1, 2 or 3, wherein R represents an alkyl radical containing from 9 to 22 carbon atoms.

8. A method of stabilizing a vinyl polymer or copo-lymer against degradation by heat and light, which comprises incorporating in the vinyl polymer or copolymer from 0.01 to 0.5 percent by weight, based on the vinyl polymer or copolymer, of a 1,4-dihydropyridine derivative represented by the general formula:

wherein R represents an alkyl radical containing from 1 to 22 carbon atoms, an octadecenyl radical a cyclohexyl radical, a phenyl radical or a phenyl radical substituted by a halogen atom or methyl or methoxy radical.

9. A method of stabilizing a vinyl polymer or copo-lymer against degradation by light, or by light and heat, which comprises incorporating in the vinyl polymer or copoly-mer from 0.01 to 0.5 percent by weight, based on the vinyl polymer or copolymer, of a 1,4-dihydropyridine derivative represented by the general formula :

wherein R represents an alkyl radical containing from 9 to 22 carbon atoms, an octadecenyl radical a cyclohexyl radical, a phenyl radical or a phenyl radical substituted by a halogen atom or methyl or methoxy radical.

10. A method according to Claim 9, wherein R
represents an alkyl radical containing from 9 to 22 carbon atoms and the 1,4-dihydropyridine derivative is present in an amount less than 0.2 percent by weight.