Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to novel plasticisers for
themoplastic polymers such as polyvinyl chloride, and more
particularly to plasticisers derived from acid endstopped
polyesters incorporating a lactone as co_reactant.
In British Patent Specification No.1,289,516 there is
claimed a process for the preparation of a substantially
primary hydroxyl-terminated linear or branched polyester
which has a maximum true melting point of 30~C containing
from 25% by weight to 70% by weight of the epsilon-
oxycaproyl unit [-O(CH2)5-C-] comprising reacting material
which will provide the epsilon-oxycaproyl unit with a least
one dicarboxylic acid or its corresponding anhydride and at
least two straight chain glycols of the formula HO(CH2)nOH
where n is an integer of 2 to 5, the proportions of the
reactants being such that the resultant polyester has the
required content of epsilon-oxycaproyl units. The polyesters
thus produced after acylation are stated to be suitable for
use as plasticisers for vinyl resins.
In British Patent Specification No.1,137,882 there is claimed
a process for the manufacture of polyesters which comprises
reacting a mixture of the following components:
(a) between 10 mole % and 65 mole % of E-caProlactone,
(b) between 45 mole % and 17.5 mole % of an aliphatic
dihydroxy compound, or of a mixture of two or more such
compounds, and
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(c) between 45 mole % and 17.5 mole % of an aliphatic
dicarboxylic acid, or of a mixture of two or more s~tch
acids, or of a mixture of one or more such acids with a
proportion not exceeding lO mole % of the total acids
used of an aromatic dicarboxylic acid, the proportions
of the components (a), (b) and (c) of the reaction
mixture being further selected, within the limits
defined above, according to the nature of the individual
compounds
constituting components (b) and (c) in such a way that the
overall ratio of carbon to oxygen atoms in the polyester
obtained excluding from consideration the oxygen atoms
present in the terminal groups, is at least 4.5:2, provided
that when component (b) consists of a single aliphatic ~
dihydroxy compound and component (c) consists of a single
aliphatic ~ dicarboxylic acid, at least one of components
(b) and (c) is a compound in which the main chain carbon
atoms carry one or more substituent groups which are lower
alkyl groups having from 1 to 4 carbon atoms. The polyesters
thus produced are stated to be useful as plasticisers for
vinyl chloride resins.
British Patent Specification No.859,642 describes polyesters
derived from lactones with at least one terminal hydroxyl
group as being useful as plasticisers for vinyl halide and
other resins. The polymerisation is initiated by such
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compounds as primary alcohols, diols containing from 2 to
10 carbon atoms and dicarboxylic acids such as phthalic acid,
isophthalic acid and terephthalic acid. It is also stated
that when the polyesters are to be used as plasticisers, the
molecular weight may range between about 1500 and about 9000
and that optimum plasticising characteristics are obtained
with polyesters having molecular weights between about 2000
and about 4000.
Surprisingly, we have found that a group of acid terminated
polyesters having a molecular weight of 500 to 1400 incorpo-
rating a lactone as co-reactant with an aromatic, or a
partially or fully hydrogenated aromatic dicarboxylic acid
and an aliphatic diol are valuable plasticisers for polyvinyl
chloride which have improved efficiency when compared with
plasticisers from similar reactants of higher molecular
weight de~cribed in BP. 859,642 and improved ease of
processing and other valuable properties when compared with
other commercially available polyester plasticisers. The
molecular weight of the polyesters described in the present
invention is determined by two factors:
1) number of moles of monocarboxylic acid reactant 'R
the ratio number of moles of dicarboxylic acid reactant
2) the mole % of the lactone used = C
Decreasing R for a given value of C,
increases the molecular weight and vice versa.
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Increasing C for a given value of R increases the
molecular weight and vice versa.
According to the present invention there is provid-
ed a compound having the formula:
M(P)a(D)b(L)cM
in which M is the residue of one or more alkanoic mono-
carboxylic acids containing from 4 to 18 carbon atoms, P is
the residue of one or more saturated straight or branched
chain aliphatic diols containing from 2 to 6 carbon atoms,
D is the residue of one or more benzene dicarboxylic acids
which may be partially or fully hydrogenated containing
from 8 to 16 carbon atoms, L is the residue of one or more
saturated acyclic hydroxy acids containing from 6 to 12
carbon atoms, each of the residues being joined together
by ester linkages, residues P, D and L being distributed
at random throughout the molecule, a, b and c each having
a value greater than 0, the amount of residue of hydroxy
acid being from 10 mole % to(90 mole ~O~based on the total
number of moles of reactants and the molar ratios of
the remaining reactants being chosen so that the average
molecular weight of the product is from 500 to 1400.
Liquid polyesters are preferred since on the commercial
scale they are much easier to handle and process than
solids polyesters.
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The average molecular weight is preferably from 600 to 1000.
The residue of the hydroxy-acid is preferably derived from
the corresponding lactone, but could be derived from the
hydroxy_acid itself.
The monocarboxylic acid corresponding to residue M preferably
contains from 6 to 12 carbon atoms, especially from 8 to
10 carbon atoms. The acid may be, for example, caproic,
caprylic, 2-ethylhexoic, isooctanoic, capric, lauric,
myristic, palmitic, coconut oil fatty acid, a mixture of
monocarboxylic acids derived from oxidation of a hydrocarbon
feedstock, or any mixture of the above acids.
The diol corresponding to residue P preferably contains from
2 to 4 carbon atoms.
The chain may, if desired, be interrupted by an oxygen atom
as in diethylene glycol. Examples of these preferred diols
are ethylene glycol; diethylene glycol5 propane_l, 2-diol;
butane-l, 3 diol; 2,2_dimethylpropane_1, 3_diol; butane-l,
4_diol; pentane_l, 5_diol; hexane-l, 6-diol; and di-propylene
glycol.
The residue D is preferably an ortho_ or meta-compound and the
dicarboxylic acid or anhydride corresponding to residue D may,
if desired, be substituted with from 1 to 4 alkyl groups
containing from 1 to 4 carbon atoms.
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The dicarboxylic acid or anhydride preferably contains
8 carbon atoms and may be isophthalic acid, but o_phthalic
acid or phthalic anhydride is particularly preferred.
The lactone corresponding to residue L may, if desired, be
substituted with one or more alkyl groups containing up to
4 carbon atoms for example, methyl. Examples of lactones are
zeta-enantholactone, eta-caprylolactone, and lambda_lauro_
lactone. However, lactones having 6 ring carbon atoms are
more preferred, and -caprolactone itself is most preferred.
When the lactone corresponding to the residue L is epsilon-
caprolactone, the amount of ~-caprolactone is preferably
20 mole % to 70 mole ~/O~ especially valuable polyesters being
obtained when the amount of ~_caprolactone is from 30 mole %
to 50 mole %.
The present invention also provides a process for the
manufacture of polyesters of formula I which comprises
reacting a mixture of the following components
a) from 10 to 90 mole % of a lactone containing from 4 to
12 carbon atoms
b) a hydroxylic component which comprises one or more
saturated straight or branched chain aliphatic diols
containing from 2 to 6 carbon atoms
A b~ n~
c) an acidic component which comprises one or more aromatic
or partially or fully hydrogenated arom ~ ie dicarboxylic
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acids or anhydrides containing from 8 to 16 carbon atoms
and
~lkct no~c
A d) one or more aliphatic monocarboxylic acids containing
from 4 to 18 carbon atoms, such that the hydroxylic
S component is used in stoichiometric amount or up to 20%
excess over the stoichiometric amount related to the
acidic components. The amount of lactone and the ratios
of the remaining reactants are chosen so that the average
molecular weight of the product is from 500 to 1400.
The process for the manufacture of the polyesters of
formula I may be carried out by conventional methods for the
manufacture of polyesters prepared solely from dihydroxy
compounds and dicarboxylic acids. For example the reaction
mixture may conveniently be heated from 100C to 250C under
conditions such that the water resulting from the condensation
reaction is removed as it is formed, for example by passing a
current of inert gas through the heated reaction mixture or by
conducting the reaction in the presence of a suitable inert
solvent such as xylene, with which the water may be removed by
distillation as an azeotrope. Preferably the reaction is
continued until the proportion of carboxylic acid end groups
in the resulting polyester corresponds to an acid value of not
more than 10 milligrams and especially not more than
5 milligrams potassium hydroxide per gram.
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If desired a catalyst co~nonly used in polyester formation
may be added to the reaction mixture for example strong
acids such as sulphuric acid, phosphoric acid, p-toluene
sulphonic acid, Lewis acids such as stannic acid, zinc
chloride, aluminium chloride and metal salts and metal
derivati~es such as metal alkoxides for example tetrabutyl
titanate, zinc adipate, antimony oxide and organo-tin
compounds especially dibutyl tin oxide. The amount of
catalyst used may be from 0.001% to 5% by weight based on the
total wei~ht of the reaction mixture. If desired up to 1% by
weight of activated carbon based on the total weight of the
reaction mixture may be added either to the reaction mixture
or just before the filtration stage to preserve the colour of
the product.
The polyesters of the present in~ention which may be used in
amounts up to 60% by weight of the plasticised composition
are efficient, easily processed plasticisers with good
extraction resistance. They show an improvement in permanence
in PVC without loss of efficiency when compared with conven_
tional non-polymeric plasticisers. In fact, the polyesters of
the present invention show a remarkable combination of
properties not present in conventional non-migratory
plasticisers: not only do they possess resistance to extrac-
tion and migration but they overcome the major defect of
plasticisers of this type since they can be readily processed
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at temperatures commonly used for monomeric plasticisers. The
polyesters of the present invention may be incorporated into
thermoplastic polymers such as polyvinyl chloride or its
copolymers by conventional methods. If desired other
conventional additives may be present in the thermoplastic
composition such as heat and light stabilisers, antioxidanLs,
fillers, pigments, lubricants, processing acids, and other
plasticisers.
Examples of heat and light stabilisers are as follows:-
1) Salts of inorganic or organic acids containing metals such
as aluminium, barium, bismuth~ calcium, cadmium, potassium,
lithium, magnesium, sodium, lead, antimony, tin, strontium
or zinc or any metal which is capable of exerting a
stabilising effect on PVC in salt form. The salts may be
8imple or complex.
Examples of inorganic salts are basic lead carbonate and
tribasic lead sulphate.
Organic acids which may be used are:
a) Aliphatic carboxylic acids, straight or branched chain
unsaturated or saturated, and optionally containing
hydroxyl substituents or oxygen in epoxy groups.
Examples are zinc 2-ethyl hexanoate, barium laurate and
stannous octanoate.
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b) Aromatic mono_ or di-carboxylic acids containing any type
of substitution in the aromatic groups and any type of
alkyl/aryl configuration.
Examples are cadmium p-tertiary butyl benzoate, calcium
benzoate or lead salicylate.
c) As acidic materials, phenols capable of forming stable
compounds, (phenates) with metals whether in a suitable
solution or not.
An example of such a compound is barium nonyl phenate.
0 2) Organo-metallic compounds of any of the following metals,
aluminium, barium, bismuth, calcium, cadmium, potassium,
lithium, magnesium, sodium, lead, antimony, zinc, tin or
strontium.
Examples of such compounds are dialkyl tin mercaptides and
dialkyl tin carboxylates.
3) Organic compounds of any description which prevent degra-
dation of PVC.
Among these are _phenyl indole or esters of amino crotonic
a_;d.
All these compounds may be used alone or as mixtures with
each other either as solids or as solutions in any suitable
solvent not necessarily being a stabiliser. Combination which
may be used are of calcium and zinc carboxylates or of a
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barium phenate with the cadmium salt of a branched chain
fatty acid or of barium, cadmium and zinc carboxylates.
There may be used with the foregoing stabilisers, materials
which enhance the effectiveness of the stabilisers but which
are not stabilisers for PVC when used alone. These are
referred to as co_stabilisers and include
a) Epoxidised oils and esters such as epoxidised soya been oil
or epoxidised octyl oleate
b) Esters of phosphorous acid which may be trialkyl, triaryl,
or alkyl-aryl. For example triphenyl phosphite, tris
(nonyl phenyl) phosphite or diphenyl isodecylphosphite
c) Aliphatic hydrophilic compounds such as pentaerythrite
neopentyl glycol, sorbitol or partial esters of glycerol
d) Phenolic compounds such as 2:6-di-tert-butyl 4-methyl
phenol, or 2:2 bis (4'_hydroxy phenyl) prop~ne.
These co-stabilisers can be used singly or together with the
m~in stabiliser in any proportions and combination. They may
be applied in their natural state, alone or in mixtures of
stabilisers, or in solvent solutions, alone or in admixture
with the stabilisers, using suitable solvents which are not
necessarily PVC stabilisers.
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They may also be used in admixture with lubricants such as
polyethylene waxes, ester waxes, stearic acid, calcium
stearate, lead stearate, fillers such as calcium carbonate
ground or precipitated or china clays.
S They may also be use~ with materials which absorb ultra-
violet light, making the PVC compound more stable to light
exposure, for example benzophenones or benzotriazoles.
They may also be used in admixture with other known
plasticisers which may be:
a) Flame retardant such as triarylphosphates, alkyl diaryl
phosphates
b) Phthalate esters
c) Low temperature plasticisers such as adipate, sebacate
and azelate esters
d) Conventional polyester plasticisers such as poly(l:3
butylene glycol adipate) end-stopped with a C8 alcohol or
other typical members of this class.
e) Aryl esters of alkane sulphonic acids
f) Extenders comprising halogenated paraffins or aromatic
hydrocarbons.
The following Examples further illustrate the present invention.
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Examples 1 to 3
A 2 litre four necked round bottom flask was fitted with a
stirrer in a ground glass stirrer gland, a 0-250C contact
thermometer in a thermometer pocket, and a nitrogen inlet.
The flask was also fitted with a vacuum jacketed Vigreux
column (6 inch effective length), surmounted by a water
separator provided with a water_cooled condenser. The amounts
of the reactants specified in Table I were charged to the
flask together with 10-15% by weight on the theoretical yield
of poly_ester of xylene and 0.1% by weight based on the
theoretical yield of polyester of dibutyl tin oxide.
Activated carbon in an amount 1% by weight based on the
theoretical yield of ester was added to the reaction mixture
in order to preserve the colour of the product.
The reactants were then heated up to approximately 200C
over 8 hours with stirring, and this temperature maintained
for a further 12, 4 and 12 hours respectively. A slow stream
of nitrogen was passed into the reaction flask throughout the
reaction. Water formed in the reaction was separated from the
xylene in the water separator. When the acid value of the
reaction mixture had reached the value given in Table 1, the
solvent was removed by heating the reaction mass under reduced
pressure. The mixture was finally vacuum stripped at 200C
for one hour at 20 millimetres mercury pressure. The product
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was filtered in a pressure filter under nitrogen and was
obtained as a clear liquid. The yields and p~operties of
these polyesters are given in Table 1.
Comparative Examples A and B
These polyesters were prepared in a similar manner to that
described in British Patent Specification 859,642 in which
phthalic anhydride, epsilon-caprolactone and ethylene glycol
in the amounts specified in Table 1 together with 0.1% by
weight based on the theoretical yield of polyester of tetra-
butyl titanate, were heated to 160C under nitrogen until thewater of condensation ceased to distil off. The reactants
were then kept at the same temperature for another 24 hours
and then subjected to a vacuum of 20 millimetres for 3.5 hours,
still at the same temperature. The yields and properties are
given in Table 1. These polyesters are outside the scope of
the present invention because they are not acid end-stopped:
also the molecular weight of the polyester of Comparative
Example B is outside the range of 500 to 1400 applicable to
this invention.
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Comparative Examples C and D
-
Polyesters C and D were prepared by heating the polyesters
prepared in Comparative Examples A and B respectively with
acetic anhydride in the amounts specified in Table 1 for
5 hours at 100C, followed by vacuum stripping for 2 hours
at 200C and 1.0 millimetre mercury pressure. The yields
and properties of these acetylated polyesters are given in
Table 1. These polyesters are also outside the scope of the
present invention because they are end-stopped by acetyl
groups, whereas the monocarboxylic acids in the po]yesters
of this ~nvention contain from 4 to 18 carbon ato~s: also the
molecular weight of the polyester of Comparative Example D
is outside the range of 500 to 1400 applicable to this
invention.
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The viscosities of the polyesters of Comparative Examp]es B
and D are so high that they are difficult to handle and
process as plasticisers.
Examples 4 to 6
The compositions of Examples 4 to 6 were obtained by
incorporating 35 parts of the polyesters of Examples 1 to 3
respectively into 65 parts of polyvinyl chloride
A (Breon S 125/12), 4 parts of white lead paste and 1 part
calcium sLearate. The premix was compounded on a two roll
mill at 165C for 15 minutes, and compression moulded at
180C for 5 minutes. The physical properties are given in
Table 2.
Comparative Examples E, F and G
The compositions of Comparative Examples E, F and G were
obtained by incorporating 35 parts of the polyesters of
Comparative Examples B, C and D respectively into 65 parts
of polyvinyl chloride (Breon S125/12), 4 parts of white lead
paste and 1 part calcium stearate. The premix was compounded
on a two roll mill at 165C for 15 minutes, and compression
moulded at 180C for 5 minutes. The physical properties are
given in Table 2.
The physical properties of the compositions of Examples 4 to 6
and Comparative Examples E, F and G were dete~ined by the
following methods:
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a) International Rubber Hardness Degrees (IRHD) tested to
BS ')03 part A7 at 23C.
b) Cold Flex (Clash & Berg) was determined according to
BS 2782 method 104B.
c) Clear Point - The temperature at which a few particles
of PVC heated in an excess of plasticiser and observed
at a magnification of X 100 with a microscope are no
longer discernible. The test indicates the relative
processability of formulations containing differing
plasticisers. In general the lower the clear point the
easier the processing of the formulation.
TABLE 2
L~ lc (5~, phr ~Cl sl~ r~i D~
4 84 8.0 125
0 127
6 87 -1 129
E could not be >200
mixed with PVC
on a roll mill
F 99 +12 136/145
G 99.5 +22 170
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The polyesters of the present invention present in the
compositions of Examples 4 to 6 have good properties as PVC
plasticisers with acceptable efficiency and Clash and Berg
values, and low clear points. In contrast the polyesters
outside the scope of this invention present in the composi-
tions of Comparative Examples E, F and G have very poor
plasticiser efficiency. This is illustrated by the fact that
the polyester present in the composition of Comparative
Example E could not be milled with PVC to give a plastic
sheet, and the IRHD values of F and G were 99 and 99.5
respectively. In addition, the polyesters present in Compara-
tive Examples E, F, and G have high clear points, and those
in cor.~parative Examples F and G confer poor low temperature
flexibility.
Comparatlve Examples H, J and K
.
The clear points w~re measured of the polyesters of
Examples 1 to 3 as well as of products sold under the Trade
Names Plastolein 9506 (Unilever-Em~ry), Arbeflex 538
(Robinson Bros.) and Palamol 644 (BASF). The results are
given in Table 3.
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TABLE 3
. _ _
Example Plasticiser Clear Point
__ _ _
Example 1 125C
Example 2 127C
Example 3 129C
E Plastolein 9506 144C
F Arbeflex 538 159C
Palamol 644 155C
It should be noted that the large difference in clear point
shown between the plasticisers in Table 3 clearly demons-
trates the superior processability of the products of this
invention, The unusually low value of the polyesters of
Examples 1 to 3 means that PVC compound can be made from
these plasticisers at lower temperatures and more quickly
than is possible with commonly used migration resistant
commercial plasticisers.
Examples 7 to 14
. _
By following a similar procedure to that described for
Examples 1 to 3 and using similar molar ratios to those
given in Table I for Example 1, polyesters can be prepared
from the reactants listed in Table IV.
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10555~6
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