MXPA97002733A - Polyester resins that have rheological properties improves - Google Patents

Abstract

The present invention relates to concentrates useful as additives for aromatic polyester resins comprising: (A) 60 to 99% by weight of a polycarbonate resin, (B) 1 to 40% by weight of dicarhydride of a tetracarboxylic acid

Description

TIE POLYESTER RESINS OUE TTENFN PROPIEDQPES REOLOGICQS PQJQRNPRS CRRIPQ OF THE INVENTION The present invention relates to aromatic polyester resin compositions having improved rheological characteristics and concentrates containing polyfunctional compounds which are used in the preparation of the compositions. Be it known that the rheological properties of the aromatic polyester resins can be improved by adding to the molten mixture functional polyac compounds which are particularly chosen among the dianhydroblasts of tet acarboxyel acids. The pyrometric dianhydpide (PMDfl) is a representative compound. The direct addition of the polyfunctional compounds to the molten mixture of the polyester resins during the extrusion phase thereof presents several drawbacks, such as the formation of gels and the lack of homogeneity of the extruded material due to the instability of the process. This is manifested by variations in the intrinsic viscosity and viscosity of the molten mixture. It is known that the addition of the polyfunctional compound, in the form of a concentrate (masterbatch) to the polyester resin, in concentrations greater than 2% by weight, preferably comprised between 8 and 12% by weight (U-R) -5 288 764), or in a polyolefin polymer in concentrations of up to about 50% by weight (UO-P-95/09884), tends to lessen the aforementioned drawbacks and can also improve the rheological properties of the molten mixture. However, the use of polyester reams to prepare the concentrates does not eliminate the reactions that produce gel formation; rather, the use of polyolefins entails the possibility of their degradation at the working temperatures of polyester reams and, therefore, the need to introduce stabilizers and similar additives. It has now been found that the addition, to the aromatic polyester resins, of polyfunctional compounds selected from the dicarboxylic acids of tetracarboxylic acids, preferably of aromatic tetracarboxylate acids, in the form of concentrates in polycarbonate resins, not only prevents the formation of gels. and the instability of the extrusion process, but also greatly improves the rheological characteristics of the ream, notably improving in particular the strength of the molten mixture, the time of suspension, the swelling in the die and the intrinsic viscosity thereof. The improvement of the rheological properties is particularly high in the case of copolyethylene terephthalate, which contains minor proportions (of about 1 to 5 mol%) of repeating units derived from isophthalic acid or other dicarboxylic acids. Thanks to the improvement of the aforementioned characteristics, the resins thus obtained have advantageous applications, especially in the area of expanded materials, in addition to the preparation of films or containers by means of molding or by blowing and extrusion. It has been found that the addition of the polycarbonate to the resin previously treated with the dianhydride, or of the polycarbonate and the dianhydride separately to the base resin in the extrusion phase, does not significantly improve the rheological properties in the case of polyethylene terephthalate or polybutylene terephthalate and similar homopolymers, although the improvements are comparable to those obtained with the concentrates when the ream is a copolyethylene terephthalate preferably containing between 1 and 20% by mole of repeating units derived from io acid talico The amount of dianhydpide added to the polycarbonate is greater than 1% by weight, preferably between 5 and 20% by weight. Amounts greater than about 50% by weight are possible, but give no particular advantage. The preferred dianhydride is pyran dianhydride! ? t i co (PrlDR). They are examples of other dianhídpdos that can be used, dianhídndoe <the 3,3 ', 4,4'-diphenyl-tetracarboxylic acid, 3,3', 4,4'-benzophenone-dicarboxylic acid 2,2-b? s (3,4-d? carbox? phenyl? , thioether b- e- (3,4-dicarboxyphenyl, tetrahydrofuranotetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, b? s (3,4-d? carbox? feml) sulfone, cyclopentyl ether tetracarboxylic acid and cyclobutyl non-tetracarbonate, the concentrate is then added to the resin in amounts such that it has a dianhydride content of between about 0.04 to 2% by weight, preferably between 0.05 and 0.5% by weight. The dianhydride and polycarbonate concentrate is preferably carried out by mixing the components in the molten state, performing it in an extruder preferably of the type of twin worms, co-rototatopos, with a residence time of approximately 1 to 2 minutes. then in the molten state with the polyester resin, and the obtained compound is molded or extruded d After that, you can obtain items such as films, fibers, beverage coners or foamed panels. The ream added together with the polyfunctional substance concentrate can be extruded and granulated and the granules can be mixed with polyester resin granules or added to the resin during the extrusion phase.

A convenient application of the ream that is added together with concentrates of the invention is the preparation of foamed articles. The superior characteristics of fusion strength, suspension time and inflation in the die obtained with the compounds of the invention, make it possible in fact to obtain, directly by extrusion and foaming, foamed material having valuable expansion properties. The technique used to achieve expansion is the conventional technique described in the literature; the foaming agents used are physical agents, such as inert gases, for example, nitrogen or carbon dioxide or aliphatic hydrocarbons such as pentane or isopentane, or also chemical foaming agents. It is preferred to use inert gases. The aromatic polyester reams used to prepare the compositions of the invention are the product of the polycondensation of aromatic dicarboxylic acids and their derivatives, such as the methyl ester having diols of 2 to 10 carbon atoms. Terephthalic acid, naphthalenedicarboxylic acids and their dimethyl ester are the preferred compounds. The diols are preferably chosen from ethylene glycol, 1,4-butanediol and 1,4-c-clohexos? D? Methanol. The polyesters may be homopolymers or copolymers containing up to about 50 mole% of other dicarboxylic acids or diols. It is preferred to use polyethylene terephthalate and its related copolymers containing up to about % by weight of the units derived from isophthalic acid or from naphthalenedicarboxylic acids, such as the 2,6 isomers, 2.7, l, 5 and 1.6. Aromatic polyesters having elastomeric properties are also used. The polyester resins are prepared in accordance with conventional procedures, by means of polycondensation in the molten state and possibly by successive polycondensation in the solid state to increase the intrinsic viscosity of the resin. The intrinsic viscosity of the resin that is used to prepare the compounds of the invention is, in general, higher than 0.4 dl / g, and is between 0.6 and 0.8 dl / g.

The intrinsic viscosity increases to values of 0.7 to 0.8 dl / g or greater, performing the extrusion in the presence of the concentrate of the invention. Additional viscosity increases can be obtained by polycondensation in the solid state of the ream which is added together with the concentrate, operating according to conventional methods. The polycarbonates used are well known in the literature. They are prepared by reaction of phenols such as bisphenol O (2, 2-b? S- (4-h? Drofen? L-propane), b? S (4-hydrofemmethane and 4,4 'bis- (4-h? drox? in? l) -heptane), with carbonate precursors such as carboyl chloride, diphenyl carbonate, d? - (a? ufemlo) carbonates, and the like (US-FL-4 598 129). carbonates may be in the form of homopolymers or copolymers, and have an intrinsic viscosity in ethylene chloride at 25 ° C which is generally comprised between 0.4 and 1.2 dl / g Fl weighted average molecular weight is generally between 20,000 and 40,000 g Polyol bicarbonate copolymers, such as those described in US-R-4 598 129 and US-R-3 169 121. The following examples are given to illustrate, but not to limit the invention. the intrinsic viscosity of the polyester resin reported in the text and in the examples by dissolving 0.5 g of polymer in 100 ml of a 60/40 mixture by weight of phenol and tetrachloroethane, operating at 25 ° C, according to RSTMD-4603-86.

AXIS? PLQ I kg / h of polycarbonate granules (Dow Caliber 0201-10) were continuously fed (after vacuum drying at 130 ° C for at least 12 hours) together with 5% by weight of pyrethylene dianhydride (PMDfl) in an extruder of contra-rotating twin worms, and they were extruded and transformed into pellets.

The conditions adopted were the following: Worm speed: 100 rpm Cylinder temperature: 280 to 285 ° C ftlirnentation of granules: 5 kg / h Mold type: round, 2 mm diameter PMDR feed: 0.25 kg / h Extruder residence time: 1 minute Strength of the melt after extrusion: less than 1 cN at 290sC and suspension time of 3 seconds.

The measurement of the melting strength was carried out using a Gottfert Rheotens equipment operating at 290 ° C (piston speed of 0.2 rnm / sec, mold dimensions: 2 n). The suspension time was determined by measuring the time (in seconds) necessary to cover a distance of 10 crn for the molten polymer at 290 ° C, leaving the capillary of the Gottfert Rheotens equipment that was used to determine the strength of the melt. The determination of the terminal COOH groups indicates that at least 80% of the added PMDft is present in the free state. The concentrate was dissolved in dichloromethane: 140 mg in 25 ml of CHSC1S; The obtained solution was extracted with 50 nrl of water under stirring for 5 rnin. The aqueous layer was then analyzed to determine the content of PMDfi; It was found that 84.6% were in a free state.

F? FMPI n nnriPRRQttvo i kg / h of a PET mixture obtained from a mixture of dimethyl terephthalate (VI = 0.6 dl / g) and 0.4% by weight of PNDR were continuously fed, after drying at 130 ° C under vacuum for at least 12 hours. hours, in an extruder of twisted worms contotrotorios worms; then they were extruded and transformed into pellets. The working conditions were identical to those of Example 1. The VI after the extrusion was 0.62 dl / g, the melting strength of 3 cN and the suspension time of 16 seconds.

E3EI1PLQ 2 kg / h of a mixture of PET from dimethyl terephthalate (VI = 0.6 dl / g) and 8% by weight of the concentrate obtained in example 1 were fed, after drying under vacuum at 130 ° C. less for 12 hours, in an extruder of counter-rotating twin worms, as in example 1. The composition by weight of the composition was: PET, 92%; PC, 7.6% and PMDR, 0.4%. The working conditions were identical to those of Example 1. The VI of the extrusion product was 0.763 dl / g; the fusion resistance of 6 cN and the suspension time of 28 seconds.

EXAMPLE 3 kg / h of a mixture of COPET (polyethylene terephthalate copolymer containing 2% by mole of isophthalic acid units, VI = 0.79 dl / g) were continuously fed, after drying at 130 ° C for at least 12 hours , together with 8% by weight of the concentrate of example 1, using the extruder and the conditions of example 1. The VI of the product after extrusion was 0.964 dl / g, the melting strength of 65 cN and the time of 125 second suspension.

E3EI1PLQ COriPñRflTIVQ 2 0.5 kg / h of a PET mixture was continuously fed from dimethyl terephthalate (VI = 0.6 dl / g) and from 7. 6% by weight of example 1, after drying at 130 ° C for at least 12 hours, to the extruder and under the conditions of example 1, and then they were extruded and transformed into pellets. The VI of the extruded material was 0.629 dl / g, the melting strength was less than 1 cN and the suspension time was 3 seconds.

EJEpPLQ CQpPfiRRTIYQ 3 kg / h of a mixture of COPET of Example 3 and 7.6% of PC of Example 1 were continuously fed, after drying at 130 ° C for at least 12 hours, to the extruder and under the conditions of Example 1. VI of the extruded material was 0.87 dl / g, the melting strength of 2.5 cN and the suspension time of 9 seconds.

EXAMPLE Polymer was subjected to 1 kg of polymer obtained according to comparative example 1, and 1 kg of polymer of the Example 2, in the solid state at 200 ° C for 4 hours. The treatment was carried out in a stirred reactor of 3.5 liter capacity in a stream of nitrogen. The VI of the polymer was 0.862 dl / g, compared to 0.826 dl / g of the polymer of comparative example l subjected to polyaddition b or the same conditions as in example 4.

EXAMPLE 5 kg / h of a mixture of COPET were fed from TPR (VI = 0.79 dl / g) containing 2% isophthalic acid) with 8% by weight of a PC / PMDñ concentrate obtained according to example 1 and 1% by weight of talc, in a twin-screw counter-rotating twin worms extruder. Before it was extruded, the mixture was dried at 130 ° C for at least 8 hours. A foaming agent (isobutane) was also fed in an amount equivalent to 1% of the weight of the mixture. The extrusion conditions are identical to those of Example 1, except for the extrusion zone which was maintained at 240 ° C. The expanded strand showed good stability and regular distribution of the cells.

Claims (8)

NOVELTY OF LR INVENTION CLAIMS

1. - Concentrates useful as additives for aromatic polyester resins comprising: (R) 60 to 99% by weight of a polycarbonate resin; (B) 1 to 40% by weight of dianhydride of a tetracarboxylic acid.

2. Concentrates useful as additives for aromatic polyester resins, according to claim 1, further characterized in that they contain from 80 to 99% by weight of polycarbonate and from 1 to 20% by weight of dianhydride of a tetracarboxylic acid.

3. Concentrates useful as additives for aromatic polyester resins, according to claims 1 and 2, further characterized in that the dianhydride is pyromellitic dianhydride.

4, - Concentrates useful as additives for aromatic polyester resins, according to claims 1 to 3, further characterized in that the polycarbonate is a resin obtained from a bisphenol and a precursor selected from enyl carbonate and phosgene.

5. A process for the preparation of the concentrates according to claims 1 to 4, characterized in that it comprises mixing the polycarbonate and the dianhydride in the molten mixture in an extruder.

6. - Aromatic polyester resins having superior rheological characteristics of melt strength and viscosity of the melted mixture, obtained by extrusion of an aromatic polyester resin added together with a certain amount of a tetracarboxylic acid dianhydride concentrate, and a resin of polycarbonate which is equivalent to a dianhydride content between 0.05 and 2% by weight.

7. Polyester resins according to claim 1, further characterized in that the resin is selected from the group consisting of polyethylene terephthalate and polyethylene terephthalate copolymers in which up to 25% by weight of the repeating units of terephthalic acid they are substituted with isophthalic acid or naphthalene dicarboxylic acid units, and the dianhydride used is pyromellitic dianhydride.

8. The resins according to claims 6 and 7, obtained by extrusion of the mixed ream with the polycarbonate ream concentrate and the tetracarboxylic acid dianhydride and successively by polycondensation of the granules in the solid state, 9.- The resins according to claim 8, further characterized in that the polyester resin is selected from the group consisting of polyethylene terephthalate containing up to 25% by weight of units deriving from isophthalic acid and naphthalene / dicarboxylic acid. 10. Foamed material obtained from the resin according to claims 6 to 9.