Note: Descriptions are shown in the official language in which they were submitted.
2 ~ 2 ~ 8
HULS AKTIENGESELLSCHAFT O.Z. 4422- PATENTABTEILUNG -
Dihydropyridines as costabilizers for mouldinq composi-
- tions based on polymers of vinyl chloride
The invention relates to rigid or plasticized, stabilized
thermoplastic moulding compositions based on halogen-
containing polymers, in particular polyvinyl chloride or
polymers containing esRentially vinyl chloride.
It i8 known that chloride-containing polymers are readily
degraded by the action of heat, for example during
processing, this degradation leading to undesired dis-
colorations and to an impairment of the mechanical
properties. Consequently, this degradation i8 avoided by
adding stabilizers to the polymers before processin~. In
; 15 the case of polyvinyl chloride and copolymers containing
essentially vinyl chloride, particular use is made of
organotin compounds, inorganic and organic lead salts,
~; organic antimony compounds or combinations of cadmium
carboxylates and barium carboxylates and also of a
mixture of zinc soaps and polyoxazolines. These so-called
primary stabilizers are frequently supplemented with
costabilizers to improve their effectiveness. The mode of
action of primary or co-stabilizers and their combined
action (synergism) are described in the relevant litera-
ture, for example in the publication by L. I. Nass, ~HeatStabilizers~, Rirk-Othmer Encyclopedia of Chemical
Technolo~y,~volum 12, 3rd edition, page 225, published
y~John Wll~y and Sons, 1980.
E~sentially, these are costabilizers which improve the
'initial colour and the ultimate stability. For instance,
epoxy compounds, polyols, organic phosphites, substituted
dihydropyridines, 1,3-diketones or else combinations of
these compoundsi are uJed.
At the pre~ènt time, no highly effective costabilizers
are available for primary stabilizers based on polymers.
Therefore, there is a need for substances or mixtures of
~ 2 - 2 ~ 3 ~ 8
substances which support or reinforce the heat- ` ~-
stabilizing action of polymeric primary stabilizers.~ ~
~ ,
Surprisingly, it has now been found that costabilizers of
the formula
Rl00C C00R
H3C i CH3 (I)~
H
in which Rl is Cg-C22-alkyl, alkenyl, cyclohexyl, phenyl or
substituted phenyl, greatly improve the stabilization.
Preference is given to the use of dihydropyridines in
~; which R1 are C9-Cl~-alkyl groups. The dihydropyridines are
generally prepared by the process published in Chem.
Reviews, 72, 1 (1972), in which an acetoacetate of the
genera} formula
CH3 - CO - CH2 - COOR
in which R = linear or~ branched Cg-C~-alkyl, alkenyl,
15~ ~ cyclohexyl, phenyl or substituted phenyl,
i8 ~reacted ~with formaldehyde and ammonia which are
optionally generated in situ.
Be-ldes the~co~tabilizer, th- stabilizer systems accord-
ing to the invention contain primary stabilizers based on
's~zinc compound and polyoxazolines. The zinc compound i~
characterized in that it contains one or more compounds
of zinc of the formula~
; R2O - Zn - oR3 (II)
in which R2 and R3 may~ b~e identical or different and
repre~ent straight-chain or branched, optionally
hydroxyl-substituted aliphatic acyl group~ having 8 to 21
.;~:
2 ~
- 3 -
carbon atoms or aryl groups which are optionally sub-
stituted by alkyl groups having 1 to 22 carbon atoms. The
C~-C21-carboxylic acids are for example benzoic acid, p-
tert-butylbenzoic acid or aliphatic carboxylic acids, in
particular octanoic acid, dodecanoic acid, stearic acid
or oleic acid.
.
Preferred examples of zinc compounds are zinc soaps of
fatty acids having 8 to 36, preferably 8 to 22 carbon
atoms. Suitable examples of these are caprylates,
caprates, laurates, myristates, palmitates, stearates and
behenates. It is also possible to use the salts of
branched fatty acids such as 2-ethylhexanoic acid,
2-octyldecanoic acid or tetradecyloctadecanoic acid or
else hydroxy-fatty acids such as 9(10)-hydroxystearic
acid or 9,10-dihydroxystearic acid. The zinc soaps may
be composed of the salts of individual fatty acids or
else from fatty acid mixtures such as are obtained from
natural fats. Suitable sa}ts of aromatic carboxylic acid~
are in particular the zinc salts of benzoic acid and of
substituted benzoic esters, in particular of alkyl-
substituted~ benzoic acid. Suitable phenolates are:
~;` methylphenolates, tert-butylphenolate~, nonylphenolates,
dodecylphenolates or naphthenates of zinc.
~ ,~ r '~ ~
The polyoxazolines used are represented by the following
formula:
_CH2 CH2
C=0 (III)
I i
R4 n
in which R~ are optionaliy different, straight-chain or
branched alkyl radicals having 1 to 22 carbon atoms or
optionally substituted ~cycloalkyl or aryl radicals,
preferably alkyl radical~ having 1 to 12 carbon atoms
;~ while n represent~ integers from 10 to 10,000 (cf.
DE-C-0,253,985). Examples of compounds of the formula III
` - 4 _ 2Q2
are polymethyloxazoline, polyethyloxazoline, poly-n-
propyloxazoline, polyisopropyloxazoline, polyundecyl-
oxazoline and polyphenyloxazoline. Other primary stabi-
li~ers which can be used are copolymers of two different
alkyl- or aryl-oxazolines each being present in a pro-
portion of between 5% and 95 %. It i8 also possible to
use terpolymers of three different oxazolines, each being
present in a proportion of 5 to 95 %.
Other highly suitable materials are those stabilized
moulding compositions which, in addition to the above~
mentioned primary stabilizers (II) and (III), contain
compounds of tin, lead or antimony or combinations of
compounds of cadmium, barium, calcium and zinc. -~
The stabilizer mixture according to the invention is used
for chlorine-containing polymers. These are preferably ;~
vinyl chloride homopolymers or vinyl chloride copolymers.
Preference is furthermore given to suspension polymers
and mass polymers and al80 to emulsion polymers. Suitabls
comonomers for the copolymers are for example: vinyl
acetate, vinylidene chloride, trans-dichloroethane,
ethylene, propylene, butylene, maleic acid, acrylic acid,
fumaric acid and itaconic acid. Other suitable chlorine-
containing polymers are post-chlorinated PVC and chlorin-
ated polyolefins, and also graft copolymers of PVC with
ethylene-vinyl acetate (EVA), acrylonitrile-butadiene-
styrene (ABS) and methacrylate-butadiene-styrene (MBS).
The stabilized moulding compositions contain the primary
~stabilizers of the formula II and III, advantageously in
~; amounts of 0.02 to 2.0 per cent by weight, in particular
in amounts of 0.05 to 1.0 per cent by weight each,
~; relative to chlorino-containing polymer.
The costabilizer according to the invention of the
formula I is advantageously used in amounts of 0.01 to
2.0 per cent by weight, preferably in amounts of 0.05 to
0.1 per cent by weight, relative to chlorine-containing
2~2~3`~i3~
-- 5 --
polymer.
The stabilized moulding compositions according to the
invention may additionally contain commercially available
costabilizers. These are, for example, epoxy compounds,
preferably epoxidized fatty acids such as epoxidized soya
bean oil, phosphites, in particular mixed aryl-alkyl
phosphites and phenolic antioxidants, which are prefer-
ably incorporated in amounts from 0.05 to 5.0, in parti-
cular 0.1 to 3.0, per cent by weight relative to chlor-
ine-containing polymer.
Suitable prior-art phosphites are phosphites of the
general formulae IV and V
R50 0
R60_p (R80)2P
R70 H
(IV) (V)
in which R5, R6 and R7 are identical or different and
denote C6-Cl8-alkyl, a phenyl radical which may be unsub-
stituted or substituted by Cl-C9-alkyl or Cl-Cg-alkoxy, or
denote C5-C,-cycloalkyl, and in which Ra is C5-Cl8-alkyl.
If R5, R6, R7 and R8 denote C6-Cl8-alkyl, this i8 for
example n-hexyl, n-octyl, n-nonyl, decyl, dodecyl,
tetradecyl, hexadecyl or octadecyl. Preference is given
to alkyl groups having 8 to 12 carbon atoms.
R5, R6 and R7, as substituted phenyl, are for example,
tolyl, ethylphenyl, xylyl, nonyl, cumyl, cresyl, 4-
~ethoxyphenyl, 2,4-dimethoxyphenyl, ethoxyphenyl, butoxy-
phenyl, p-n-octylphenyl or p-n-nonylphenyl.
Most particularly suitable phosphites are trioctyl,
- ,.. , . ~ . . . .. . .... ..
2~
- 6 -
tridecyl, tridodecyl, tritetradecyl, tristearyl, tri-
oleyl, triphenyl, tricresyl, tris-p-nonylphenyl and
tricyclohexyl phosphite and particular preference is
given to the aryl dialkyl phosphites and also to the
alkyl diaryl phosphites such as for example phenyl
didecyl phosphite, nonylphenyl didecyl phosphite, (2,4-
di-tert-butylphenyl) didodecyl phosphite and (2,6-di-
tert-butylphenyl) didodecyl phosphite.
Examples of antioxidants are alkylated monophenols and
hydroquinones, hydroxylated thiodiphenyl ethers, 1,4-
alkylidene-bis-phenols, benzyl compounds, acylamino-
phenols, esters or amides of ~-(3~5-di-tert-butyl-4-
hydroxyphenyl)propionic acid and esters of ~-(5-tert-
butyl-4-hydroxy-3-methylphenyl)propionic acid.
Preferred antioxidants are alkylated monophenols, alkyli-
dene-bisphenols and phenyl-substituted propionic esters,
in particular, however, 2,6-di-tert-butyl-p-cresol, 2,2-
bis(4'-hydroxyphenyl)propane and n-octadecyl ~-(3,5-di-
tert-butyl-4-hydroxyphenyl)propionate.
The compound of the formula I can also be used with other
nitrogen-containing organic stabilizers. Examples of
these are cyanamide, dicyandiamide, guanamines such as
benzoguanamine, indoles such as phenylindole, paryzoles
(for example as described in GB-B-866,936), ureas and
thioureas such as monophenylurea and diphenylthiourea,
and aminocrotonic esters; al~o, ~-diketones such as
stearylbenzoylmethane, and polyols such as pentaerythri-
tol.
It was observed, with the stabilized moulding composi-
;~ 30 tions according to the invention based on polymers of
vinyl chloride which contain a compound of the formula I
as costabilizer, that this compound reinforces the
stabilizing action of a primary stabilizer mixture of
zinc compounds and polymers from the group of
polyoxazolines to an extent which could not have been
_ 7 _ 2~
foreseen. The positive effect of this costabilizer is
seen in an improvement in the initial colour and in a
prolongation of the ultimate stability. Although DE-A-
2,844,130 employs dihydropyridines as stabilizers for
vinyl chloride polymers, the stabilizer mixtures employed
in the above-cited document differ from the stabilizer
mixtures according to the present invention with regard
to the primary stabilizers.
It is possible to prepare the stabilized moulding com-
positions according to the invention by customary
methods, for example by simple mechanical mixinq of the
components in conventional mixers. This mixing operation
may be used to incorporate other customary processing
auxiliaries such as for example lubricants (montan waxes
or polyol partial esters), plasticizers, fillers, light
stabilizers, pigments or other costabilizers such as for
example epoxidized fatty acid esters.
It is possible to achieve a homogeneous distribution of
the stabilizers in PVC, for example with the aid of a
two-roll mill at 150 to 200C.
i
Preparation and testing of milled sheet
The action of the stabilizer combinations was tested by
determining the static heat stability of milled sheet.
For this purpose, the stabilizer combinations and option-
ally plasticizers and processing auxiliaries were mixed
with polyvinyl chloride for 30 seconds on a laboratory
mill and then processed on a two-roll mill at a roll
temperature of 170-C, with co-rotation, in the course of
5 minutes to form 1 mm thick milled sheets. Strips of
dimensions 14 x 250 mm were cut from the milled ~heets
and these strips were then sub~ected to heat stress in a
special oven (Metrastat, type Sigma) at 180C. Under the
test conditions, the test strips were continuously
discharged from the heating zone and show the effect of
the stabilizers from the colour variation.
`J i~
-- 8 --
The colour variations were assessed ob~ectively and the
test strips compared with each other by determining the
yellowness indices (YI; ASTM Method E 313-73 ) using a
colorimeter (LabScan 5100 plus) from Dr. Slevogt ~ Ca.
S and plotting the yellowness indices against the duration
of heat stress. High YI values indicate strong discolor-
ation and thus low stability.
The following stabilizers were used:
Zn = zinc stearate
Ba = barium stearate
PX = polyethyloxazoline
PC = copolymer of methyl- and isopropyl-oxazoline
TMP = trimethylolpropane
DHP = dihydro-dimethyl-bis(dodecyloxycarbonyl)pyridine
Formulations were prepared from the following ingredients
(part~ = parts by weight):
Formulation A
- 100 parts of suspension-polyvinyl chloride
(R-value 70; VESTOLIT S 7054;
Huls AG, Marl)
;~ - 30 parts of dioctyl phthalate (VESTINOL AH;
Huls AG, Marl)
- 0.3 part of montan wax
Formulation B t
- 100 parts of suspension-polyvinyl chloride
(K-value 70; VESTOLIT S 7054;
Huls AG, Marl)
- 30 parts of dioctyl phthalate (VESTINOL AH;
Huls AG, Marl)
- 0.3 part of zinc stearate
- 0.6 part of barium stearate
~ ' ~
9 2~$~
Formulation C:
- 100 parts of suspension~polyvinyl chloride
(K-value ~0; VESTOLIT S 7054;
Huls AG, Marl)
- 1.0 part of stearic acid
Formulation D:
- 100 parts of suspension-polyvinyl chloride
~R-value 60; VESTOLIT S 6058;
H~ls AG, Marl)
- 1.0 part of stearic acid
Formulation E:
- 100 parts of suspension-polyvinyl chloride
(K-value 58; VESTOhIT M 5867;
Huls AG, Marl)
- 5.0 parts of epoxidized soyabean oil
(Reoplast 39, Ciba-Geigy AG,
Bensheimf)
f~he invention is further explained and the surprising
technical advance is confirmed by the examples which are
described below.
The polyvinyl chloride moulding compositions were pre-
pared by adding stabilizers from the given tables to the
formulations A to E and these mixes were processed in the
manner described-above to form test strips.
; .
::~
~::
",
lo- 2~
Comparison of the results of the heat test, with and
without costabilizer
Stabilizer composition: Zinc stearate (Zn)
Polyethyloxazoline (PX)
Copolymer of methyl-
oxazoline and iso-
propyloxazoline (PC)
Trimethylolpropane (TMP)
and costabilizer: Dihydropyridine (DHP)
_
Formulation Zn~PX/DHP/ Zn/PC/DHP/
without with without with
TMP TMP . TMP TMP
. _
S 7054 better better
Stearic acid
'': ~: ,
:~ S 70S4 better better
VESTINOL AH
~: Zn stearate ;
: 20 Ba stearate
.......
S 705;4 better better
-VESTINOL AH .
~montan wax
(corr. to~Wax~E)
S 6058 better better
Stearic acid ~ :
:
M 5867 better bet~er
Reoplast 39
: . : ~ ;
~ .
~:
3 J ~3
Constituents of the stabilizer compositions in parts by
weight
6tabilizer mixtures Zn PX PC T~P DHP
Zn/PX 0.2 0.2
Zn/PC 0.2 0.2
Zn/PX/TMP 0.2 0.2 0.5
Zn/PC/TMP 0.2 0.2 0.5
Zn/PX/DHP 0.2 0.2 0.07
Zn/PC/DHP 0.2 0.2 0.07
Zn/PX/TMP/DHP 0.2 0.2 0.5 0.07
Zn/PC/TMP/DHP 0.2 0.2 0.5 0.07
;
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- 14 -
Formu l at i on 80 . _
lOO parts by wt. of r
~ESIOLiT S 7054 ,
~ O . . . ~
30 pdrts by wt. of
'/EST~NOL AH / !
0 3 part by wt. of Yl . 40 _ _ ¦ _ _
Zlnc stearate / .'
0.6 part by wt. of / . -
8ar;um stearate ~ .~
~ ._.L_~_
Stabilizers 10 1S 20 26 30 36 40 45 l l 60 ~.
Zn/PC (cf.) - 12 12 15 20 17 14 16 25 5~ . _ ..
Zn/PCtT M P (cf,)8 9 9 U 13 13 13 14 33 86 .
Zn/PC~DHP -*- 7 8 ~ 13 17 21 20 15 27 72 . Yl
Zn/PCtrM P/DHP 4 S S 7 ~ U 13 19 11 18 34
heat stress lminl
Formul ati on ~
-
100 parts by wt. of l
VÉSTOLST S tO54 80 ~ L__ _
30 parts by wt. of
VESTINOL AH ~o _ ----~ -T-- -
0.3 part by wt. of yl , ~;
Zinc stearate
0.6 part by wt. of 40 _ _ _
Barium stearate ,~ f
. 20 ~
- ~ -
~ Stabi l i 7ers 10 15 _ 3a 35 40 45l50l55lBO-
`~ ~ Zn~PC (cf.) 12 12 16 20 17 1~ 15 26 5~ _ _
Zn~PCtTMP(cf.) -+- 8 ~ ~ U 13 t5 13 14 33 85 _
Zn~PC~DHP 7 8 ~ 13 17 21 20 t6 27 72 _ Yl
Zn~PCtTMP~oHp~ . 4 6 5 7 ~ t2 13 13 n ts 34 ~ ~:
heat stress Iminl
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