Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
A-20445/A/CGM 461
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Stabiliæd PVC compositions
The invention relates to compositions comprising a vinyl halide homopolymer (PVC) and
a thermoplastic copolymer based on styrene, butadiene and acrylonitrile (ABS), which
comprise at least one organotin compound and an oxide or hydroxide of an aLkali metal or
alkalinP earth metal as stabilizer combination, to the use of these compositions and of the
stabilizer combination, and to a method of stabilizing PVC moulding compositions.
Organotin compounds are customarily employed as stabiliærs in connection with the
processing of PVC/ABS compounds by injection moulding. In the course of such
processes the material can be stressed in two ways: firstly by means of shear forces
(fricative stress) and secondly by high temperatures. In both cases, the loading increases
on longer residence times in the processing apparatus. For such applications there
continues to be a search for effective stabilizer combinations which offer maximum
protection against degradation by thermal and fricative stresses.
The combined use of organotin compounds, m~gnPsi~lrn oxide and hydrotalcites is known
for PVC (EP-A-0 256 872).
It has now been found that the use of certain tin stabilizers in combination with aLkali
metal or ~lk~line earth metal hydroxides and/or oxides leads to surprisingly good stabilizer
properties for PVC/ABS compounds and blends.
The invention accordingly provides a composition comprising
(a) 20-75 parts by weight of a vinyl chloride homopolymer (PVC),
(b) 80-25 parts by weight of ABS,
(c) at least one organotin compound of one of formulae I to VII
[Rl]iSn[-Q-R2]4 i (I)
IRl
[ Sn-Q-R6-CO~}~ (II)
Rl
~ ~ 7 ~
Rl
[ Sn-S-R3-COO-R7-O-CO-R3-S ]k (III)
R
Rl S-R3-coo-R7-o-co-R3-s IRl
~S-R3-COO-R7-O-CO-R3-S-Sn< >Sn~ (IV)
S-R3-Coo-R7-o-Co-R3-S
IRl Rl
R8-COO~SIn-X~n-O-CO-R8, (V)
Rl Rl
RpSnSq (VI) or [RpSnSq]r (VII)
in which
R and
Rl independently of one another are Cl-Cl2aLkyl or C3-CllaL~oxycarbonylethyl,
Q is -s- or -O-CO-, and
R2, if Q is -s-, is C8-Cl8aIkyl or a radical -R3-Coo-R4 or -R3-o-Co-R4, and
R2, if Q is -o-co-, is Cl-Cl8alkyl, C2-Cl8aL~enyl, phenyl, Cl-C4aLlcyl-substituted phenyl
or a radical -CH=CH-COO-Rs,
R3 is methylene, ethylene or o-phenylene,
R4 is C5-Cl8alkyl,
Rs is Cl-Cl8aL~yl, Cs-C7cycloaL~yl or benzyl,
R6, if Q is -S-, is methylene, ethylene or o-phenylene, and
R6, if Q is -O-CO-, is Cl-C8alkylene, o-phenylene or a group -CH=CH-,
R7 is C2-C4alkylene or is C4-C8alkylene interrupted by -O-,
R8 is Cl-Cl8alkyl, C2-Cl8alkenyl, phenyl, Cl-C4aL~yl-substituted phenyl, or a radical
-CH=CH-COO-Rs,
each X independently of the others is -O- or -O-CO-R9-COO-,
R9 is Cl-C8alkylene, o-phenylene or a group -CH=CH-,
p is 1 or 2, q is [(4-p)/2] and r > 1,
i is the number 1 or 2, j is a number from the range from 1 to 6, k is a number from the
range from 1 to 3 and m is a number from the range from 1 to 4,
217~6Sl
and
(d) at least one oxide and/or hydroxide of an alkali metal or alkaline earth metal.
Above, in all of the description and in the claims, the abbreviation -COO- used denotes the
groOup
~ O , and the abbreviation -O-CO- the group
-0-~_ -
Rl, R2, R4, Rs and R8 as alkyl, within the confines of the respective number of carbon
atoms indicated, are for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
tert-butyl, pentyl, hexyl, heptyl, octyl, isooctyl, nonyl, decyl, undecyl, dodecyl, tridecyl,
tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl.
Isooctyl denotes the alkyl radicals of the mixture of primary branched alcohols R'CH2OH,
which derives from the oxo process and in which R' is a branched heptyl group (Merck
Index lOth.ed., 5041).
R as alkyl is preferably n- and isoalkyl radicals, particularly preferably methyl, ethyl and
n-butyl.
Rl as alkyl is preferably methyl, butyl or octyl.
R and Rl as C3-Cllalkoxycarbonylethyl are Cl-C8alkyl-O-CO-CH2-CH2-.
R2 and R8 as C2-Cl8alkenyl are, inter alia, ethenyl (vinyl), propenyl, isopropenyl,
2-butenyl, 3-butenyl, isobutenyl, n-penta-2,4-dienyl, 3-methyl-but-2-enyl, n-oct-2-enyl,
n-dodec-2-enyl, isododecenyl, n-heptadec-8-enyl, n-octadec-2-enyl and n-octadec-4-enyl.
R2 and R8 as Cl-C4alkyl-substituted phenyl comprise, for example, methylphenyl,
dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl,- isopropylphenyl and tert-
butylphenyl.
R2, R6, R8 and R9 as -CH=CH-COO-Rs or -CH=CH- are derived from maleic acid or
fumaric acid, preferably from maleic acid.
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Rs as Cs-C7cycloaLkyl is cyclopentyl, cyclohexyl or cycloheptyl, preferably cyclopentyl or
cyclohexyl, especially cyclohexyl.
R6 and R7 as alkylene are a divalent alkyl radical; within the confines of the chain lengths
indicated, R6 and R7 are for example methylene, ethylene, -CH(CH3)-CH2-, -(CH2)3-,
-(CH2)4-. -(CH2)6-~ -(CH2)8-. -cH2-cH(c2Hs)-(cH2)4-~ -CH2-C(CH3)2-CH2-;straight-chain radicals are preferred. R7 as C4-C8alkylene interrupted by -O- is for
example -(CH2)2-O-(CH2)2-,-(CH2)3-O-(CH2)3-.-(CH2)2-o-(cH2)4- or
-(CH2)4-O-(CH2)4-, especially -(CH2)2-O-(CH2)2-. The unit (O-CH2-CH2) may also be
present more than once. Examples of such radicals are (CH2)2-(O-CH2CH2-)2- and
-(CH2)2-(O-CH2CH2-)3--
There is no upper limit on the index r, since the sulfides may be amorphous, coordinative-
ly crosslinked laffice structures. It is also possible, as in formula VI, to dispense with the
representation of this state of affairs. Formulae VI and VII are therefore essenti~lly inter-
changeable. Structural examples of the sulfides can be found below under "Typical
Sulfides".
As component (c) the compositions according to the invention preferably comprise a
mixture of compounds. Compositions cont~ining only one compound as component (c),
however, are also part of the inventi~n and have the same advantageous properties.
Where the compositions according to the invention comprise compounds of the formulae I
to V as compounds of component (c), preference is given to those in which
Rl is Cl-Cl2aL~yl,
R2, if Q is -S-, is C8-Cl8alkyl or a radical -R3-Coo-R4, and
R2, if Q is -O-CO-, is C7-Cl8alkyl, C8-Cl8aLkenyl, phenyl or a radical -CH=CH-Coo-R5,
R3 is methylene, ethylene or o-phenylene,
R4 is Cs-Cl8alkyl,
Rs is Cl-Cl8alkyl or Cs-C7cycloalkyl,
R6, if Q is -S-, is methylene, ethylene or o-phenylene, and
R6, if Q is -O-CO-, is Cl-C4alkylene, o-phenylene or a group -CH=CH-,
R7 is C2-C4aLkylene or is C4-C8alkylene interrupted by -O-,
R8 is Cl-CI8alkyl, C2-Cl8alkenyl, phenyl or a radical -CH=CH-COO-Rs,
R9 is butylene, o-phenylene or a group -CH=CH-,
i is the number 1 or 2, j is a number from the range from 1 to 6, k is a number from the
21 -~6~1
range from 1 to 3 and m is a number from the range from 1 to 4.
With particular preference, in the compounds of formulae I to V,
Rl is C3-Cgalkyl,
R2, if Q is -S-, is a radical -R3-Coo-R4, and
R2, if Q is -O-CO-, is C7-Cllalkyl or a radical -CH=CH-Coo-R5,
R3 is methylene or ethylene,
R4 is C8-Cl8alkyl,
Rs is Cl-Cl8alkyl or cyclohexyl,
R6, if Q is -S-, is methylene or ethylene, and
R6, if Q is -O-CO-, is a group -CH=CH-,
R7 is -C2H4-,
R8 is C8-Cl2alkyl or a radical -CH=CH-COO-Rs,
R9 is a group -CH=CH-,
i is the number 1 or 2, j is a number from the range from 1 to 6, k is a number from the
range from 1 to 3 and m is a number from the range from 1 to 4.
The substituents on said groups -CH=CH- are with particular preference in cis position (Z
configuration) and are derived in the compounds from maleic acid.
Particular prerelellce is also given to compositions which comprise as component (c) at
least one compound of the formula I or III in which
Rl is butyl or octyl, R3 is -CH2-, R7 is -C2H4-, where Q = S: R2 is -CH2-Coo-R4 and R4
is C8-Cl2alkyl, and where Q = O-CO: R2 is -CH=CH-COO-Rs and Rs is Cl-Cl8alkyl.
The compositions according to the invention preferably comprise from 20 to 50% of
component (a) and from 80 to 50% of component (b).
Component (c) is generally present in a proportion of from 0.5 to 5% by weight [based on
(a) and (b)], in particular from 1.5 to 4%; component (d) is expediently present in a
proportion of from 0.1 to 4% by weight (based on (a) and (b)), in particular from 1 to
2.5%.
Preferred polymer compositions are those comprising as components (a) and (b) a mixture
of 25-75% by weight of PVC and 75-25% by weight of ABS. Examples of such composi-
tions are: 25-50% by weight of PVC and 75-50% by weight of ABS, or 40-75% by weight
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of PVC and 60-25% by weight of ABS.
Examples of metals which can be present in the compounds of component (d) are Li, Na,
K, Mg, Ca, Sr or Ba. Compounds preferred as component (d) are NaOH, KOH and
Ca(OH)2, CaO, MgO and Mg(OH)2, particularly preferably CaO, Ca(OH)2, MgO or
Mg(OH)2, and with especial preference CaO.
The composition according to the invention comprises components (c) and (d) preferably
in a ratio of from 0.8 to 50 parts by weight of (c) to 1 part by weight of (d), in particular
from 2 to 35 parts by weight of (c) to 1 part by weight of (d).
The established abbreviation "PVC" is familiar to the person skilled in the art. What this
abbreviation refers to is dealt with in current reference works [e.g. Ullmann's
Encyclopedia of Industrial Chemistry, 5th ed. (1985)].
ABS is a copolymer of styrene, acrylonitrile and but~diPnç. The elastomeric component,
usually but~liPnP or a but~iPnP copolymer, is present in this case as a discrete phase in
the thermoplastic component, a styrene/acrylonitrile copolymer. The elastomer particles
are prepared by known methods, such as by bulk polymeri7~tion or suspension polymeri-
7ation, but especially by emulsion polymerization. The elastomer particles are weakly
crosslinkPd and have in general an average diameter of from 0.1 to 50 llm, preferably from
0.5 to 5 ~m. Regarding the multifarious use of ABS, see for example H.B. Savenije,
Kunststoffe 83, 763 (1993).
The compositions according to the invention are prepared by known methods. The stabili-
zers are admixed to the polymer blends in a known manner before or during proces.~ing A
homogeneous mixture can be obtained, for example, before processing with the aid of a
heating-cooling mixer at usually up to 120C in the heating phase.
The compositions according to the invention can also advantageously comprise customary
qu~ntitiçs of further, conventional PVC stabilizers and/or other additives, for example
epoxy compounds, metal soaps, i.e. essentially metal carboxylates and metal phenolates of
metals from the second main group and subgroup of the Periodic Table, or else inorganic
salts of metals from the second subgroup of the Periodic Table, and also antioxidants.
The further stabili7ers mentioned immediately above are preferably incorporated in
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quantities of from 0.05 to 6%, in particular from 0.1 to 3%, based on the overall
composition.
Metal soaps are principally metal carboxylates of preferably relatively long-chain
carboxylic acids. Common examples are stearates and laurates, as well as oleates and salts
of relatively short-chain alkylcarboxylic acids. Use is often made of so-called synergistic
mixtures such as barium/zinc, m~pnesium/zinc, calcium/zinc or calcium/m~gnP.si~lm/zinc
stabilizers. The metal soaps can be employed individually or in mixtures. A review of
customary metal soaps can be found in Ullmann's Encyclopedia of Tn(lllstri~l Chemistry,
5th ed., Vol. A16 (1985) p. 361 ff.).
Preferred antioxidants are alkylated monophenols, aLkylidenebisphenols, and propionic
esters substituted with so-called sterically hindered phenol radicals, examples being
2,6-di-tert-butyl-p-cresol, 2,2-bis(4'-hydroxyphenyl)propane and n-octadecyl
~-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.
Depending on the intended use of the compositions according to the invention, it is
possible before or along with the incorporation of the stabilizer for other additives to be
incorporated as well, examples being lubricants (preferably mont~n waxes, glycerol esters,
fatty acid esters or paraffins), fillers (carbon black, kaolin, TiO2, talc, silicates, glass
fibres), pigments, light stabiliærs, UV absorbers, flameproofing agents and ~nti~t~tic
agents. It is preferred if such further additives are not hydrotalcites.
Preferred such additives are lubricants, pigments, processing aids, fillers, antioxidants
and/or light stabilizers.
Components (c) and (d) of the compositions according to the invention, and optional
additives, can also be added to the polymers to be stabilized in the form of a masterbatch.
This masterbatch can comprise, for example, from 10 to 40% by weight of component (c),
from 1 to 20% by weight of component (d), and polymers of components (a) or (b),costabilizers such as processing aids, lubricants and flameproofing agents, or acombination of these substances.
The compositions according to the invention can be processed to form moulded parts by
the shaping processes customary for this purpose, for example by injection moulding or
extrusion.
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The compositions according to the invention are preferably used for the preparation of
injection moulded parts. This use is also part of the invention. Examples of such parts are
pipes, fittings and apparatus housings, for example for telephones and computers.
The organotin compounds of formulae I to VII are known (see for example the literature
references cited at the outset and also US 5,021,491 and the references therein: US
2,731,482, US 2,731,484, US,2,713,585, US 2,648,650, US 3,507,827). They may in
particular be carboxylates, mercaptides and s~-lfi~les.
Typical mercaptides are: methyltin tris(alkylthioglycolate) or tris(alkylthio-propionate), n-butyltin tris(alkylthioglycolate), n-butoxycarbonylethyltin tris(alkyl-
thioglycolate), dimethyltin bis(alkylthioglycolate) or bis(alkylthiopropionate);di-n-butyltin bis(alkylthioglycolate) or bis(alkylthiopropionate); bis-n-butoxy-carbonylethyltin (alkylthioglycolate) and n-octyltin tris(isooctylthioglycolate).
Typical sulfides of the formulae VI and VII are
n-Bu
Sn ~ Sn
n-Bu ~ ¦ ¦ n-Bu and
~ Sn
n-Bu n-Bu
n-Bu
S
S
n-BuSn S\ / Sn-n-Bu
S- Sn--__s
n-Bu
Typical carboxylates are di-n-butyltin bis(methylm~lPate), di-n-butyltin bisbutyl-
maleate and polymeric di-n-butyltin m~lP~te. The carboxylates may also comprise
mixtures, for example the mixture consisting of 40% by weight of the compound
~ ~ 7~
g
S - CH2
(C8Hl7)2Sn~ ,CH2 and 60% by weight of the compound
O - c=O
"
(C8H17)2sn~ 11; or the mixture consisting of 66.7% by weight of the compound
o - cO
S - CH2
(CsH17)zsn CH2 and 33.3% by weight of the compound
O - C=O
o--c'
`CH
(CsH17)2Sn 1 1
'O
Together with the compounds of component (c) of formulae I to VII it is also possible for
further tin stabiliærs to be present in the compositions according to the invention,
provided they do not adversely affect the improved properties obtained by means of the
compounds mentioned Preference, however, is given to the compositions according to the
invention which apart from the above-described organotin compounds of component (c)
and their comproportionation products comprise no further tin stabiliærs
From the chPmi.~try of organotin stabiliærs it is known that, in the stabiliæd substrate,
these stabiliærs are often no longer present in the same form in which they were added.
Usually, reaction products (comproportionation products) are formed. The invention also,
of course, embraces compositions which comprise such products formed from the
compounds of component (c) corresponding to formulae I to VII.
The invention also provides the stabilizer combination comprising the initially described
components (c) and (d) and, if desired, further additives.
The invention additionally provides for the use of the stabiliær combination just defined
for stabilizing moulding compositions comprising 20-75% by weight of a vinyl chloride
homopolymer (PVC) and 80-25% by weight of ABS. This also includes a method of
stabilizing moulding compositions comprising (a) 20-75% by weight of a vinyl chloride
homopolymer (PVC) and (b) 80-25% by weight of ABS, which comprises adding said
stabilizer combination to the compositions.
2 ~ 7~6~ 1
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The examples which follow illustrate the invention in more detail but without restricting it
in any way. As in the rest of the description, parts and percentages are by weight unless
specified otherwise.
Example 1:
46 g of the two PVCtABS compounds described in Table I (for compositions see Table I)
are subjected to thermal and fricative stress (by means of shear forces) in the kn~.a(ling
chamber of a Brabender Plasticorder at 45 rpm and 190C. At 5-minute intervals, samples
(about 0.5 g) are taken of the plasticated PVC/ABS composition, and are subsequently
pressed at 180C for 1.5 min~l~es to give test specimens. These specimens are subjected to
colorimetric determinA~ion in order to obtain the colour difference ~E acccording to DIN
6174 (CIE-LAB 1976). Small colour differences imply good stabilizer action. The values
are compiled in Table II.
Table I
Brabender heat test at 190C
Mixture 1 2
[parts] [parts]
S-PVC Kvalue 57 35 35
ABS 65 65
PMMA flow aidl) 2.0 2.0
Lubricant2) 1.25 1.25
Lubricant3) 0.25 0.25
Flameproofing
agent Sb2O3 4.0 4.0
Chlorinated
polyethylene 3.0 3.0
MBS (impact modifier) 5.0 5.0
Organotin mercaptide4) 2.4 2.4
Calcium oxide -- 0.5
)Polymethyl m~lL~ 2)Ester wa~c 3)Po~ L~ wax 4)Mi~cture of 30 % mono-n-butyltin
tris(i~lylll.io~ ~late) and 70 % di-n-butyltin bis(iso~ly- -glycolate)
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able II: Colour difference of the test specimens made from samples taken at the
specified times
Colour difference ~E (according to DIN 5033/DIN 6174) after
minutes 15 20 25 30 35 40
Mixture
20.6 24.5 30.4 35.2 39.0 decomposition
2 19.8 23.7 29.6 32.8 35.8 40.5
For the composition according to the invention after thermal stress, the measurement
results show a lower colour difference, which points to a better heat-stabilizing action than
the CaO-free composition.
