Stabiliser compositions for halogenated polymers containing beta-diketone, hydrotalcite and dihydropyridine, and polymers stabilized therewith.

The invention relates to new stabilizing compositions for halogenated polymers, said compositions comprising a beta-diketone, a hydrotalcite, a dihydropyridine. It also relates to halogenated polymers stabilized by means of said compositions.

It has already been proposed (Japanese application 80445/80) to use hydrotalcites as stabilizers for polyvinyl chloride (PVC). Stabilization by means of hydrotalcite alone or in combination with the usual metal salts, for example calcium stearate leads to very average thermal stability (see European patent 0063180).

It has also been proposed (European patent application 0189899) to stabilize synthetic resins containing halogens and / or acidic substances by means of solid solutions of hydrotalcites containing at least one divalent metal cation chosen from the group consisting of Mg, Ca, Sr and Ba, at least one second divalent metal cation chosen from the group consisting of Zn, Cd, Pb and Sn and a trivalent metal cation (AI, Bi, In, Sb, B, Ga or Ti and in particular AI).

Furthermore, it has been proposed (US 2,669,548, US 3,001,970, GB 1,141,971, US 3,493,536, US 4,102,839, US 4,123,999, US 4,123,400) to use, alone or in combination with metal salts, for example zinc salts, beta-diketones for stabilization of PVC.

It has also been proposed (European patent 0063180) to associate a beta-diketone with a hydrotalcite free from the second divalent metal cation mentioned in the European patent application 0189899 cited above (Zn, Cd, Pb and Sn) for the stabilization of polymers containing halogens.

It has also been proposed (Japanese application 61-113635) to stabilize halogenated polymers by means of a composition comprising a hydrotalcite and a dihydropyridine.

It has also been proposed (US 4,267,083) to combine a beta-diketone with a dihydropyridine in order to stabilize PVC.

In general, the various aforementioned stabilizing compositions lead to an improvement in the thermal stability of the halogenated polymer. Experience has shown, however, that the color stability over time is generally achieved at the expense of the resistance of the polymer itself to the usual processing or processing temperature, that is to say between 180 and 225 'C.

The subject of the invention is new stabilizing compositions for halogenated polymers, said compositions comprising at least one stabilizer consisting of a metal salt of carboxylic acid and being characterized in that they comprise:<ul id="ul0001" list-style="none"><li>a) at least one beta-diketone</li><li>b) at least one hydrotalcite comprising at least one divalent metal cation chosen from the group consisting of Mg, Ca, Sr and Ba, at least one metal cation chosen from the group consisting of Zn, Cd, Pb and Sn and at least one cation trivalent metallic</li><li>c) at least one dihydropyridine</li></ul>

Beta-diketone can be chosen from the group consisting of products of formula:<chemistry id="chem0001" num="0001"><img file="EP0362012A1_D0001.tif" /></chemistry>in which :<ul id="ul0002" list-style="none"><li>- R, can represent H, a hydrocarbon radical containing up to 18 carbon atoms, optionally substituted by one or more halogens or hydroxy groups, alkoxy, ester, alkyl, alkoxycarbonylalkyl having from 1 to 8 carbon atoms or - COR_z) ;</li><li>- R₂ may represent H, OH, a hydrocarbon radical having up to 18 carbon atoms, unsubstituted or carrying at least one of the substituents mentioned above for R, with the exception of - COR₂, knowing that if Z = R₂ or if n is between 1 and 3, only one of the symbols R₂ represents H;</li><li>- a radical R, and a radical R₂ or two radicals R₂ can together form a divalent alkylene cyclic radical;</li><li>- n is between 0 and 3;</li><li>- Z is chosen from the group consisting of R₂ and a polyvalent radical chosen from the group consisting of a direct bond between the COs, a radical R₃, a radical<chemistry id="chem0002" num="0002"><img file="EP0362012A1_D0002.tif" /></chemistry></li><li>where R₃ is a polyvalent hydrocarbon radical having up to 18 carbon atoms;</li><li>R₄ and Rs represent H or a hydrocarbon radical having up to 18 carbon atoms or together form a divalent alkylene cyclic radical;</li><li>X represents - 0 - or - S -</li><li>m is 0 or 1</li><li>R₆ may represent H, a hydrocarbon radical having up to 18 carbon atoms or R₃.</li></ul>

Beta-diketones can be used as such or in their enolic form and in particular in the form of their metal enolates or organotin enolates.

Hydrotalcite can be represented by the formula:<chemistry id="chem0003" num="0003"><img file="EP0362012A1_D0003.tif" /></chemistry>in which :<ul id="ul0003" list-style="none"><li>- <chemistry id="chem0004" num="0004"><img file="EP0362012A1_D0004.tif" /></chemistry>represents at least one divalent metal cation chosen from the group consisting of Mg, Ca, Sr and Ba;</li><li>- <chemistry id="chem0005" num="0005"><img file="EP0362012A1_D0005.tif" /></chemistry>represents at least one divalent metal cation chosen from the group consisting of Cd, Pb, Zn and Sn;</li><li>- M3⁺ represents a trivalent metal cation;</li><li>- AT^z- represents a valence anion z;</li><li>- x, y1, y2 and w correspond to the relations:<maths id="math0001"><img file="EP0362012A1_D0006.tif" /></maths><maths id="math0002"><img file="EP0362012A1_D0007.tif" /></maths><maths id="math0003"><img file="EP0362012A1_D0008.tif" /></maths><maths id="math0004"><img file="EP0362012A1_D0009.tif" /></maths><maths id="math0005"><img file="EP0362012A1_D0010.tif" /></maths></li></ul>

Dihydropyridine can be represented by the formula:<chemistry id="chem0006" num="0006"><img file="EP0362012A1_D0011.tif" /></chemistry>in which the symbol R represents a monovalent radical chosen by the alkyl, alkenyl, cycloalkyl, aryl, alkylaryl and arylalkyl radicals having up to 20 carbon atoms.

The preparation of each of the aforementioned components (beta-diketone, hydrotalcite, dihydropyridine and metal salt) is widely described in the literature and does not in itself constitute an object of the invention.

In formula 1 (beta-diketone), the symbols Ri, R₂ and R₃ represent more particularly alkyl radicals before from 1 to 18 carbon atoms, cycloalkyl, cycloalkylalkylene or alkylcycloalkyl having from 5 to 18 carbon atoms or aryl, alkylaryl or aralkyl having from 6 to 18 carbon atoms.

By way of illustration of the beta-diketones which can be used in the compositions in accordance with the invention, mention may be made in particular of cyclohexanedione-1,3, methylene bis cyclohexanedione-1,3, 2-benzyl-cyclohexanedione-1,3, l acetyltetralone, palmitoyltetralone, stearoyltetralone, benzoyltetralone, 2-acetyl cyclohexanone, 2-benzoyl cyclohexanone, 2-acetyl cyclohexanedione-1,3, benzoyl p.chlorobenzoylmethane, bis (methyl) benz methane, bis (2-hydroxy benzoyl) methane, benzoylacetone, tribenzoylmethane, diacetylbenzoylmethane, stearoylbenzoylmethane, palmitoylbenzoylmethane, lauroylbenzoylmethane, dibenzoylmethane, bis (4-chloro-benzyl) benzyl (benzoyl) -methane, bis (4-chloro-benzoyl) methane, bis (4-chloroyl) stearoyl (4-methoxybenzoyl) methane, butanoylacetone, distearoylmethane, acetylacetone, stearoylacetone, bis (cyclohexanoyl) methane, dipivaloylmethane.

Among these beta-diketones, preference will be given to stearoylbenzoylmethane, to benzoylacetone, to stearoylacetone.

Among the hydrotalcites of formula (II), preference is given in the invention to the products represented by said formula (II), with the following meanings for the various symbols:<ul id="ul0004" list-style="none"><li>- <chemistry id="chem0007" num="0007"><img file="EP0362012A1_D0012.tif" /></chemistry>represents Mg or Ca or a combination of Mg with Ca, Sr or Ba and even more Mg or Mg / Ca;</li><li>- <chemistry id="chem0008" num="0008"><img file="EP0362012A1_D0013.tif" /></chemistry>represents Zn, Cd, Zn / Cd and even more Zn;</li><li>- M³⁺ represents AI;</li><li>- AT^z- represents a valence anion z such that <chemistry id="chem0009" num="0009"><img file="EP0362012A1_D0014.tif" /></chemistry>, OH-, <chemistry id="chem0010" num="0010"><img file="EP0362012A1_D0015.tif" /></chemistry>, <chemistry id="chem0011" num="0011"><img file="EP0362012A1_D0016.tif" /></chemistry>, an acetate (-), salicylate (-), citrate (3-), tartrate (2-) ion, <chemistry id="chem0012" num="0012"><img file="EP0362012A1_D0017.tif" /></chemistry>, I^-, <chemistry id="chem0013" num="0013"><img file="EP0362012A1_D0018.tif" /></chemistry>, <chemistry id="chem0014" num="0014"><img file="EP0362012A1_D0019.tif" /></chemistry>[Fe (CN)₆]^4-, <chemistry id="chem0015" num="0015"><img file="EP0362012A1_D0020.tif" /></chemistry>and preferably A^z- represented <chemistry id="chem0016" num="0016"><img file="EP0362012A1_D0021.tif" /></chemistry>or OH^-; - x, y₁, y₂ and w have the following relationships:</li><li>0.2 &lt;x &lt;0.5 and preferably 0.25 &lt;x &lt;0.35, y₁ &gt; _Y2 and 0 &lt;w &lt;2.</li></ul>

One or more hydrotalcites of the formula are used in particular:<maths id="math0006"><img file="EP0362012A1_D0022.tif" /></maths>x, y1, y2 and w having the meanings given above.

Among the dihydropyridines of formula (III), use is particularly made of the products in the formula of which the symbols R represent an alkyl radical having from 1 to 12 carbon atoms and in particular methyl, ethyl, lauryl, an alkenyl radical containing up to 6 carbon atoms, a cyclohexyl radical, a phenyl radical.

Among these products, mention will be made most particularly of 2,6-dimethyl-1,4-dihydro-pyridine 3,5-diethyl and dilauryl dicarboxylates.

The metal salt of carboxylic acid can be derived from one of the 2-ethylhexanoic, lauric, myristic, palmitic, stearic, hydroxystearic, linoleic, behenic, isostearic, oleic, ricinoleic, caproic, heptanoic, n- acids. or iso-octyl, pelargonic, neotridecanoic, acrylic, linolenic, crotonic, acetoacetic, acetic, maleic, thiodipropionic, dithiopropionic. It is also possible to use the partial esters of the aforementioned dibasic acids with aliphatic, cycloaliphatic or aromatic alcohols. It is also possible to use cyclic acids such as benzoic, methylbenzoic, butylbenzoic, benzoylbenzoic, ptbutylbenzoic, phenylacetic, salicylic, naphthoic, abietic, phenylstearic, naphthenic, cinnamic or pyrrolidone carboxylic acids. The metal salts of said acids can be derived from the following metals: Li, Na, K, Mg, Ca, Sr, Ba, Pb, Zn, Cd, Zr, AI, Si, Sn, Sb and Bi. Use is preferably made of one or more salts chosen from acetates, acetoacetates, stearates, oleates, laurates, palmitates, benzoates, hydroxystearates, 2-ethyl calcium hexanoates, barium, zinc and cadmium optionally in the form of couples such as Ca / Zn, Ba / Ca, Ca / Cd or Ba / Zn.

In the stabilizing compositions in accordance with the invention, the abovementioned additives are advantageously used in the following proportions (by weight):<tables id="tabl0001" num="0001"><img file="EP0362012A1_D0023.tif" /></tables>(not taking into account any additives to these constituents, which will be discussed later).

The invention also relates to halogenated polymers stabilized by means of the composition described above.

Although these compositions can be used for the stabilization of polymers containing halogens supplied by the catalytic system and / or agents for treating polymers, such as polyolefins obtained with Ziegler catalysts or post-halogenated and in particular post-chlorinated polymers , for example polyolefins or post-chlorinated rubbers, the compositions are very particularly suitable for the stabilization of polymers at least partially derived from halogenated monomers. They may, for example, be fluorinated polymers such as polyfluoroolefins, in particular polyfluoroethylenes or polyvinyl fluoride or polyvinylidene. The invention applies very particularly to homopolymers and copolymers obtained from vinyl chloride. Among the copolymers, mention will be made in particular of copolymers of vinyl chloride and of at least one monomer chosen from the group consisting of vinylidene chloride, ethylene, acrylic or methacrylic acid esters, styrene, esters vinyl, maleic acid and anhydride, maleic acid esters, this list being given for information only. The invention relates very particularly to copolymers containing at least 50% and preferably at least 80% by weight of copolymerizable vinyl chloride.

Homopolymers of vinyl chloride can be prepared according to the techniques now known, namely in bulk, in suspension or microsuspension or in dispersion.

The above homopolymers and copolymers may be rigid or flexible and, as the case may be, may contain the usual additives such as impact-enhancing agents, pigments and / or fillers, plasticizers, antioxidants or light or ultraviolet stabilizers.

The compositions may also contain additional stabilizers such as alkyl- or arylphosphites and / or epoxidized compounds such as epoxidized soybean oil, and / or polyols, in particular the compounds comprising at least 2 and preferably at least 4 groups hydroxyl, such as D-xylitol, D-sorbitol, D-mannitol, diglycerol, 4-hydroxy, tetrahydroxymethyl 3,3,5,5 tetrahydrofuran, trihydroxyethylisocyanurate, polyvinyl alcohol, trimethylolpropane , tetramethylolcyclohexanol, quinic acid, adonitol, alphamethylglucoside, glycerol.

The compositions may also contain zinc salts, acrylic polymers, butadiene-based terpolymers, for example MBS resins, internal or external lubricants such as ester waxes, fatty acid esters, polyethylene, oxidized or not, hydrogenated castor oil, glycerol mono-oleate, esters of montanic acid, magnesia or any other complexing product of water released by the hydrotalcite giving a thermally stable product and having no negative influence on the stabilization of the polymer.

The halogenated polymer compositions stabilized using the stabilizing compositions according to the invention may contain up to 5% of stabilizing composition, relative to the weight of the halogenated polymer. Preferably; they contain 0.5 to 3% of stabilizing composition.

Relative to its main constituents, a stabilized composition in accordance with the invention more particularly contains, per 100 parts of halogenated polymer (preferred values ​​in brackets):<tables id="tabl0002" num="0002"><img file="EP0362012A1_D0024.tif" /></tables>

With the exception of plasticizers which can in general be used at rates which can reach 100% of the weight of the halogenated polymer, the various abovementioned additives can be used at rates which can go from 0.05 to 20% of the weight of said polymer.

The stabilizing composition according to the invention can be prepared separately or, most often, be formed in the presence of all or part of the halogenated polymer and / or, if necessary, of all or part of the additives which may be used. The usual techniques for mixing the different ingredients can be used. One can in particular use a turbo-mixer making it possible to obtain a dry powder at the end of the operation of mixing the ingredients with the polymer. In general, this mixing operation, and in particular when using the turbo-mixer mentioned above, can be carried out at a temperature which can reach 80 to 120 C.

The stabilized composition can be shaped using the usual techniques such as injection molding, extrusion molding, calendering.

The stabilizing compositions in accordance with the invention are characterized, in terms of halogenated polymers stabilized by means of said compositions, by a remarkable association of the color fastness (or non-coloring) over time with the resistance to thermal destruction of the polymer in the usual temperature conditions for shaping said polymer. However, it should be noted that this combination (change in coloring, resistance to temperature) is not observed, either with the constituents a, b and c, tested separately, or with the pairs formed from these constituents.

The following example, which is given for information only, illustrates the invention.

EXAMPLE

<tables id="tabl0003" num="0003"><img file="EP0362012A1_D0025.tif" /></tables>

2.- Preparation of samples

The polymer and the liquid additives are then introduced into a turbo-mixer, making a predispersion for 30 seconds at low speed (approximately 600 rpm). The solid additives are then introduced to complete the mixing of the additives and the polymer (with the exception of the stabilizing composition, the content of which will be determined independently for each mixture). The mixture is first heated up to a maximum of 100 ° C., by means of a double jacket and rapid stirring (around 1800 rpm). Thereafter, the masterbatch is cooled to 40 ° C during draining.

Aliquots are taken from the masterbatch produced for the separate addition of the stabilizing compositions to be tested. The final mixtures, produced under conditions identical to the previous ones (only the maximum temperature reached is 95⁰ C) are then located and isolated to protect from humidity.

The implementation of these dry blends depends on the evaluation test to be performed.

3.- Evaluations

3.1- Measurement of the total blackening time of the mixture produced with the 7-plate Emidecau press (400 mm x 400 mm) heated by steam circulation, at 185 C

The implementation of this test requires working on test pieces that have been pregelified on an open mixer and cut from the sheet produced in the mixer.

Description of the realization of the test pieces

On a LESCUYER 2-cylinder mixer (700 mm x 300 mm), rotating at a speed of 8 m / min, without friction, and adjusted to the temperature of 180 ° C and 1 ° C, the dry powder mixture is introduced, then it is gels for 5 min measured from the introduction of the powder between the cylinders. The sheet produced, of exactly 1 mm thick, is cut with a circular-shaped cookie cutter, after cooling the sample between two unpressed aluminum plates.

Description of the static thermal stability measurement test

From the sample pellets thus produced, the series of samples is introduced at the same time into the 7-tray press and the samples are taken every 5 or 10 minutes, until the tablet is completely blackened, the corresponding time of which is noted in the results table.

3.2- Measurement of the dynamic evolution of the yellowing index (YI: ASTM D 1925-70) on film samples made at 195 C, on a Lescuyer 500 mm x 200 mm mixer, with polished steel cylinders

Realization of. test

The dry powders of the corresponding mixtures are introduced into the Lescuyer mixer, rotating at the speed of 8 m / min, without friction and adjusted to the temperature of 195 "C ± 2 ° C. The spacing between cylinders is adjusted to obtain, at from the 200 g initially introduced, a homogeneous film 1 mm thick.

Every 4 minutes, from the introduction of the powder chosen as the original time, samples are taken directly on the mixer from a rectangular cookie cutter, then cooled between unpressed aluminum plates. A measurement of the Yellowness Index (function of the elementary components L, a, b) is carried out at particular times representative of the transformation of PVC at this temperature, using a HUNTERLAB colorimeter model D 25 M PC 2 with orifice 1 inch diameter sighting.

The values ​​expressed in terms of YI are noted below:<tables id="tabl0004" num="0004"><img file="EP0362012A1_D0026.tif" /></tables>

Remarks

The best results (coloring / blackening time) are obtained with the composition based on the Ca / DHP / SBM salt / hydrotalcite mixture.

Note that DHP-based mixtures used alone and in large doses (&gt; 0.1 per) lead to significant fluorescence.