CA1069132A

CA1069132A - Polyester plasticisers

Info

Publication number: CA1069132A
Application number: CA233,705A
Authority: CA
Inventors: Frank Lamb
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1974-08-21
Filing date: 1975-08-19
Publication date: 1980-01-01
Also published as: JPS5154641A; IT1041891B; NL7509888A; SE7508444L; ZA755339B; SE419231B; FR2282441B1; BE832567A; FR2282441A1; AU8411575A; ES440338A1; DE2536224A1; GB1454920A

Abstract

Abstract of the Disclosure Caprolactone modified polyesters derived from an ali-phatic dihydroxy compound and a mixture of aliphatic di-carboxylic acids and a proportion above 10 mol % of the totel acids used, of an aromatic dicarboxylic acid and terminated with an alcohol or monocarboxylic acid such that the molecular weight ranges from 500 to 1400 are good plasticisers for polymers, especially polyvinyl chloride.

Description

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The present invention relates to novel plasti-cisers for thermoplastic polymers such as polyvinyl chlo-ride, and more particularly to plasticisers derived from polyesters incorporating ~-capro-lactone as co-reactant.
In British Patent Specification No. 1,137,882 there is claimed a process for the manufacture of poly-esters which comprises reacting a mixture of the following components:
a) between 10 mole % and 65 mole % of ~-caprolactone, b) between 45 mole ~/0 and 17.5 mole % of an aliphatic di-hydroxy compound, or of a mixture of two or more such com-pounds, and c) between 45 mole % and 17.5 mole % of an aliphatic di-carboxylic acid, or of a mixture of two or more such acids, or of a mixture of one or more such acids with a propor-tion not exceeding lO mole % of the total acids used of an aromatic dicarboxylic acid, the proportions of the com-ponents (a), (b) and (c) of the reaction mixture being fur-ther selected, within the limits defined above, according to the nature of the individual compounds constituting com-ponents (b) and (c) in such a way that the overall ratio of carbon to oxygen atoms in the polyester obtained, ex-cluding from consideration the oxygen atoms present in the

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terminal groups, is at least 4.5:2, provided that when com-ponent (b) consists of a single aliphatic a,~-dihydroxy compound and component (c) consists of a single aliphatic ,~-d~carboxylic acid, at least one of components (b) and 5 (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.
There may also be included in the reaction mix-ture from which the polyester is obtained, in addition to components (a), (b) and (c) already defined, a monohydroxy compound or a monocarboxylic acid and the preferred ratio of monohydroxy compound to di-hydroxy compound, or mono-carboxylic acid to dicarboxylic acid respectively is be-tween 5 mole % and 50 mole %. The polyesters thus produced are stated to be useful as plasticisers for vinyl chloride resins.
British Patent Specification ~o. 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 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 ,, ~ -'. : ... - ' lO~gl3Z

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 characteri-stics are obtained with polyesters having molecular weights between about 2000 and about 4000.
We have found surprisingly that caprolactone modi-fied polyesters derived from an aliphatic dihydroxy com-pound and a mixture of aliphatic dicarboxylic acids and a proportion above 10 mole % of the total acids used, of an aromatic dicarboxylic acid, and terminated with an alcohol or monocarboxylic acid such that the molecular weight ranges from 500 to 1400 are more efficient, have lower clear points, and the combination of viscosity and clear point is better for use as PVC plasticisers than comparable products des-cribed in B.P. 859,642, i.e. when the produc~s described in BP 859,642 have comparable viscosity with those of the pre-sent invention, they have higher clear points, and when the products described in B.P. 859,642 have comparable clear points, they have higher viscosities and are usually solid.
According to the present invention there is pro-vided a polyester having the formula M(P)a(D)b(L)CM

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in which M is the residue of one or more aliphatic mono-carboxylic acids or one or more saturated straight or bran-ched chain monohydric alcohols containing from 4 to 12 car-bon atoms, P is the residue of one or more saturated straight or branched chain aliphatic diols containing from 2 to 4 car-bon atoms, D is the residue of a mixture of one or more ali-phatic dicarboxylic acids containing from 4 to 6 carbon atoms and a proportion above 10 mole % of the total acids used, of one or more aromatic dicarboxylic acids containing from 8 to 16 carbon atoms, L is the residue of 6-hydroxy Jolneo~
B caproic acid, each of the residues being jointcd 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 % 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 solid polyesters.
The residue of 6-hydroxy caproic acid is prefer-ably derived from epsilon caprolactone but it could be deri-ved from 6-hydroxy caproic acid itself in the preparation of , - ' ,, ' ' . " ', ,; ' .; , . . '~, : -- - :. , . : .
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the compounds of formula I.
When M is the xesidue of a monocarboxylic acid, the acid preferably contains from 8 to 10 carbon atoms. The acid may be, for example, caproic, caprylic, 2-ethylhexoic, isooctanoic, capric or lauric acid. When M is the residue of a monohydric alcohol, the alcohol preferably contains from 8 to 11 carbon atoms. The alcohol may be for example, n-butanol isobutyl alcohol, n-hexanol, isooctyl alcohol, nonanolJisodecyl or dodecyl alcohol. Particularly preferred alcohols are isooctyl alcohol (a commercially available mix-ture containing branched chain primary alcohols with eight carbon atoms), "Aphanol" 79 (which consists mainly of straight-' .~
and branched-chain primary alcohols containing 7-9 carbon atoms~, 2-ethylhexanol, isodecyl alcohol, Alfol 810 (a com-mercial product consisting mainly of n-octanol and n-decanol), the mixtures of predominantly straight chain aliphatic alco-hols containing 7 to 9 carbon atoms sold under the Trade Mark "Linevol" 79, and the mixture of predominantly straight chain aliphatic alcohols containing 9 to 11 carbon atoms sold under the Trade Mark "Linevol" 911.
The diol corresponding to residue P may be, for example, ethylene glycol; diethylene glycol; propane-1,2-diol; butane-1,3-diol or butane-1,4-diol. The chain may, if rat6/e m ~ks .
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desired, be interrupted by an oxygen atom as in diethylene glycol.
The aliphatic dicarboxylic acid or anhydride cor-responding to residue D may be for example succinic acid, glutaric acid or adipic acid or the anhydrides. A commer-cially available mixture containing 27.4% succinic acid, 42.4% glutaric acid and 30.2% adipic acid is particularly useful.
The aromatic dicarboxylic acid or anhydride corre- ~;
sponding to residue D may, if desired, be substituted with from 1 to 4 alkyl groups containing from 1 to 4 carbon atoms.
The dicarboxylic acid or anhydride preferably con-tains 8 carbon atoms and may be isophthalic acid, but o-phthalic acid or phthalic anhydride is particularly preferred.
` 15 The amount of ~-caprolactone is lO to 90 mole %, preferably 20 to 70 mole %, but most preferably 30 to 50 mole %.
The present invention also provides a process for the manufacture of polyesters of for~ula I which comprises reacting a mixture of the following components a) from 10 to 90 mole % of epsilon caprolactone or the corresponding hydroxy acid, b) a hydroxylic component which comprises one or more saturated straight or branched chain aliphatic diols .- . .
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containing from 2 to 4 carbon atoms c) an acidic component which comprises a mixture of one or more aliphatic dicarboxy-lic acids containing from 4 to 6 carbon atoms and a propor-tion above lO mole % of the total acids used of one or more aromatic dicarboxylic acids containing from 8 to 16 carbon . atoms and d) one or more aliphatic monocarboxylic acids con-: taining from 4 to 12 carbon atoms, or one or more saturated straight or branched chain monohydric alcohols containing from 4 to 12 carbon atoms such that the hydroxylic components are used in stoichiometric amounts up to 20% excess over the stoichiometric amounts related to the acidic components.
The amount of lactone and the ratios of the remaining reac-tants 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 condensa-tion 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 .
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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 `5 an acid value of not more than 10 milligrans and especially not more than 5 milligrams potassium hydroxide per gram.
If desired a catalyst commonly used in polyester formation may be added to the reaction mixture for example 8trong 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 derivatives such as metal alkoxides for example tetrabutyl titanate, zinc adipate, antimony oxide and organo-tin com-pound especially dibutyl tin oxide. The amount of catalyst used may be from 0.001% to 5% by weight based on the total weight of the reaction mixture. If desired up to 1% by weight of activated carbon based on the total weight of the reac-tion 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 invention which may ~ -be used in amounts up to 60% by weight of the plasticised composition are efficient, easily processed plasticisers _ g _ ~0~ii9132 with good extraction resistance. They show an improvement in permanence in PVC without loss of efficiency when com-pared with conventional 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 extraction and migration but they overcome the major de-fect of plasticisers of this type since they can be readily processed at tèmperatures commonly used for monomeric plasti-cisers.
A further major practical advantage of these novel plasticisers is their much lower viscosities, compared with conventional non-migratory polyester plasticisers. This leads ` to much easier handling, more rapid dispersion of mixtures and easier cleaning of equipment.
i The polyesters of the present invention may be in-, corporated into thermoplastic polymers such as polyvinyl chloride or its copolymers by conventional methods. If de-sired other conventional additives may be present in the thermoplastic composition such as heat and light stabilisers, j antioxidants, fillers, pigments, lubricants, processing aids, and other plasticisers.
Examples of heat and light stabilisers are as fol-lows:

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' ' ' ~ , : ' ~ ' 1) Salts of inorganic or organic acids containing metals such as aluminium, barium, bismuth, calcium, cadmium, potas-sium, lithium, magnesium, sodium, lead, antimony, tin, stron-tium or zinc or any metal which is capable of exerting a stabilising effect on PVC in salt form. The salts may be simple or complex.
Examples of inorganic salts are basic lead carbo-nate 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.
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 solu-tion or not. An example of such a compound is barium nonyl phenate.
2) Organo-metallic compounds of any of the following metals, aluminium, barium, bismuth, calcium, cadmium, potassium . .

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Examples of such compounds are dialkyl tin mercap-tides and dialkyl tin carboxylates.

3) Organic compounds of any description which prevent de-gradation of PVC.
Among these are ~-phenyl indole or esters of amino crotonic acid.
All these compounds may be used alone or as mix-tures with each other either as solids or as solutions in any suitable solvent not necessarily being a stabiliser.
Combinations which may be used are of calcium and zinc car-boxylates or of a barium phenate with the cadmium salt of a branched chain fatty acid or of barium, cadmium and zinc car-boxylates.
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 bean oil or epoxidised octyl oleate b) Esters of phosphorous acid which may be trialkyl, triaryl or alkyl-aryl. For example triphenyl phosphite, tris (nonyl 10~i9132 phenyl) phosphite or diphenyl isodecylphosphite.
c) Aliphatic hydrophilic compounds such as pentacrythritol neopentyl glycol, sorbitol or partial esters of glycerol.
d) Phenolic compounds such as 2:6-di-tert-butyl 4-methyl S phenyl, or 2:2 bis (4'-hydroxy phenyl~propane.
These co-stabilisers can be used singly or toge-ther with the main stabiliser in any proportions and com-binations. 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.
They may also be used in admixture with lubricants such as polyethylene waxes, ester waxes, stearic acid, cal- -cium stearate, lead stearate, fillers such as calcium car-bonate ground or precipitated or china clays. -They may also be used 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.

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~069132 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 hydrocar~ons.
The following Examples further illustrate the pre-sent invention.
The acid value is determined by dissolving a sample of the polyester in neutralised ethanol (or an etha-nol-toluene mixture) and titrating with N/10 sodium hydro-xide solution using phenolphthalein as indicator. The re-sult is expressed in mg KOH per g.
The hydroxyl value is measured by acetylating the polyester with excess acetic anhydride in ethyl acetate with p-toluene sulphonic acid as catalyst followed by hy-drolysis of unreacted acetic anhydride, This reaction mix-ture, and an aliquot of the acetylation reagant are titra-ted with standard alkali. The difference in the titres gi-ves a measure of the acetic anhydride which is reacted with the hydroxyl groups and from this figure the hydroxyl value .
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10~9132 (in mg KOH per g) can be calculated.
The viscosity is measured using an Ubbelohde sus-pended level viscometer (ASTM D445-IP71).

Examples 1 to 6 A 2 litre four necked round bottom flask was fit-ted 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 ( 12 cm (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 polyester of xylene and 0.1% by weight based on the theoretical yield of polyester of di-butyl 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 pro-duct.
The reactants were then heated up to approximately 200C over 8 hours with stirring, and this temperature main-.

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10~i9132 tained for a further iO to 20 hours. A slow stream of ni-trogen 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 I, 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 was filtered in a pressure filter under nitrogen and was obtained as a clear liquid. The yields and properties of these polyesters are given in Table 1. The "mixed dicar-boxylic acids" referred to in Table 1 is a commercially available product with the approximate composition:
succinic acid 27.4 %
glutaric acid 42.4 %
adipic acid 30.2 %

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Comparative Examples A and B
. These polyesters were prepared from the reactants specified in Table 2 by a similar method to that described in Examples 1 to 6 but in Example B tetra-butyl titanate was used as catalyst. The yields and properties are given in Table 2.
Comparative Examples C and D
The polyester of Comparative Example C was pre-pared in a similar manner to that described in British Pa-tent 859,642.
The polyester of Comparative Example D was pre-pared by acetylating 400 grams of the polyester of Example C
with 116 grams acetic anhydride for five hours at 100C. Ex-cess acetic anhydride and acetic acid were then removed un-der vacuum. The yields and properties are given in Table 2.
Comparative Examples E and F
The polyester of Comparative Example E was pre-pared in a similar manner to that described in British Pa-tent Specification 859,642 in which phthalic anhydride, ep-silon-caprolactone and ethylene glycol in the amounts speci-fied in Table 2 together with 0.1% by weight based on the theoretical yield of polyester of tetra-butyl titanate, were heated to 160C under nitrogen until the water of con-densation ceased to distil off.

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loNj9 i 32 The reactants were then kept at the same temperature for another 24 hours and then subjected to a vacuum of 20 milli-metres for 3.5 hours still at the same temperature. This polyester is outside the scope of the present invention be-cause it is not end-stopped.
The polyester of Comparative Example F was prepared by heating the polyester prepared in Example E with acetic an-hydride in the amounts specified in Table 2 for 5 hours at 100C, followed by vacuum stripping for 2 hours at 200C
and 1.0 millimetre mercury pressure. This polyester is out-side the scope of the present invention because it is end-stopped by acetyl groups whereas the polyesters of the pre-sent invention are end-stopped by alcohols or acids contain-ing from 4 to 12 carbon atoms.
The yields and properties of these polyesters are given in Table 2.

Examples 7 to 12 The compositions of Examples 7 to 12 were obtained by incorporating 35 parts of the polyesters of Examples 1 to 6 respectively into 65 parts of polyvinyl chloride (Breon S
B 125/12) 4 parts of white lead paste and 1 part calcium stea-*~ ro~ m~-k . .

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rate. The premix was compounded on a two roll mill at 165C
for 15 minutes, and compr~ssion moulded at 180C for 6 minu-tes. The physical properties are given in Table 3.
Comparative Examples G to L
The compositions of Comparative Examples G to L
were obtained by incorporating 35 parts of the polyesters of Comparative Examples A to F respectively into 65 parts of polyvinyl chloride (Breon S 125/12), 4 parts of white lead paste and 1 part calcium stearate. The premix was com-pounded on a two roll mill at 165C for 15 minutes, and com-pression moulded at 180C for 6 minutes. The physical pro-perties are given in Table 3.
The physical properties of the composition of Examples 7 to 12 and Comparative Examples G to L were de-termined by the following methods:
a) International Rubber Hardness Degrees (IRHD) tested to BS 903 part A7 at 23C. This indicates the efficiency.
b) 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 .

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Claims

CLAIMS:

1. A polyester having the formula M(P)a(D)b(L)CM I
in which M is the residue of one or more aliphatic mono-carboxylic acids or one or more saturated straight or branched chain monohydric alcohols containing from 4 to 12 carbon atoms, P is the residue of one or more saturated straight or branched chain aliphatic diols containing from 2 to 4 carbon atoms, D is the residue of a mixture of one or more aliphatic dicarboxylic acids containing from 4 to 6 carbon atoms and a proportion above 10 mole % of the to-tal acids used, of one or more aromatic dicarboxylic acids containing from 8 to 16 carbon atoms, L is the residue of 6-hydroxy caproic acid, each of the residues being joined together by ester linkages, residues P, D and L being di-stributed 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 % 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.

2. A polyester as claimed in claim 1 in which the residue of 6-hydroxy-caproic acid is derived from epsilon caprolactone.

3. A polyester as claimed in claim 1 or claim 2 in which M is the residue of a monocarboxylic acid containing from 8 to 10 carbon atoms.

4. A polyester as claimed in claim 1 or 2 in which M is the residue of isooctanoic acid.

5. A polyester as claimed in claim 1 or claim 2 in which M is the re-sidue of a monohydric alcohol containing from 8 to 11 carbon atoms.

6. A polyester as claimed in any of claims 1 or 2 in which M is the residue of isooctyl alcohol.

7. A polyester as claimed in claims 1 or 2 in which the diol corres-ponding to residue P is ethylene glycol.

8. A polyester as claimed in claim 1 or 2 in which the residue of the aliphatic dicarboxylic acid or anhydride corresponding to residue D is derived from succinic, glutaric or adipic acid or anhydride.

9. A polyester as claimed in claim 1 or 2 in which residue of the aro-matic dicarboxylic acid or anhydride corresponding to residue D is derived from 0-phthalic acid or phthalic anhydride.

10. A polyester as claimed in claim 1 or 2 in which the amount of epsilon caprolactone is from 20 to 70 mole % based on the total number of moles of residues.

11. A composition comprising a thermoplastic polymer and a plasticis-ing amount of a compound according to claim 1 or 2.

12. A composition comprising polyvinyl chloride and a plasticising amount of a compound according to claim 1 or 2.