MXPA99005642A - Modified polyesters - Google Patents

Abstract

The invention concerns the use of a copolymer comprising (a) between 60 and 98 wt%methylmethacrylate, and (b) between 2 and 40 wt%styrene, and optionally (c) between 0 and 20 wt%maleic acid anhydride, as modifying agents for increasing the melt viscosity for partially crystalline, partially aromatic polyesters, with the exception of polybutylene terephthalate containing intensifier fillers.

Description

Modified Polyesters The invention relates to the use of methacrylate / styrene copolymers as modifiers of the melting rheology of partially crystalline partially aromatic polyesters. The invention further relates to modified polyesters and the parts made therefrom. Current state of the art. Partially aromatic partially crystalline polyesters, such as for example polyethylene terephthalates and polybutylene terephthalates, find a wide field of application especially in the packaging materials industry, for example food packaging, in the automotive industry or in the textile industry, for example in the manufacture of synthetic fibers, due to its exceptionally good resistance to solvents and its good forming characteristics with a minimum of thermal shrinkage. Many pieces formed as for example bottles of beverages, tanks of gasoline, systems of suction, etc. They are made of these materials by injection or extrusion-blowing. US-PS 4 179 479 discloses blends of synthetic materials which may consist of 40% by weight of polyurethane and a maximum of 60% by weight of polybutylene terephthalate and between 0.5 and 10% by weight of weight polyacrylate polymers molecular (arithmetic average) from 500,000 to 1,500,000 as coadjuvants for production. The polyacrylate may be, inter alia, a terpolymer of methyl methacrylate, n-butyl acrylate and styrene. No monomer contents are indicated in the polymer. EP 0 328 273 Bl discloses fusion thermoplastic resin fusion modifiers consisting of polymers with an average molecular weight of between 1,500,000 and 10,000,000 of (meth) acrylate monomers with radicals which may be alkyls, substituted alkyls, cycloalkyls, aryls, aralkyls or alkylaryls. Example 58A describes a modification of polybutyl terephthalate with 10% by weight of a polymer consisting of 74% methyl methacrylate, 24% butyl methacrylate and 2% methacrylic acid with a molecular weight of 4.9 x 106. By the modification additive raises the sag time by extrusion (a measure of melt viscosity) from 5.2 seconds to 10.5 seconds compared to unmodified polybutylene terephthalate. US 5 352 500 claims articles formed by blowing a thermoplastic resin containing approximately 1 to 25% by weight of methacrylate polymers consisting of 70% of (meth) acrylate monomers with radicals which can be alkyl, substituted alkyl, cycloalkyl , aryl, aralkyl or alkylaryl. In the examples 2 - . 2-4 shows the modification of a mixture of polybutylene terephthalate and polycarbonate (43/57) with a tenacity modifier based on polymethyl methacrylate / styrene having a core-shell structure. The modification leads to the increase of the warpage time by extrusion (a measure of the viscosity of the melt). DE-OS 23 64 318 describes the modification of poly-1,4-butylene terephthalate or its copolyesters with a small amount of an aliphatic or aromatic dicarboxylic acid or of an aliphatic polyol containing 1 to 80% of a filler-reinforcing substance in the form of metals, ceramics, silicates, quartz, glass and reinforcing carbon by the addition of mixed polymers or copolymers containing styrene. The addition of a mixed polymer of polypropylene and styrene that modify the rubber to polybutylene terephthalate reinforced with glass fiber according to the examples produces an improvement of the thermal stability of the pieces and a better resilience of the synthetic material. Among a number of suitable copolymers are also those of methyl methacrylate and styrene. The effect of the elevation of the melt viscosity is not reported or mentioned since many of the mentioned additives, on the contrary, produce a reduction in the melt viscosity.

Objective and solution. A fundamental problem in the work of partially crystalline partially aromatic polyester types, such as for example polyethylene terephthalate or polybutylene terephthalate, consists in that the viscosity decreases rapidly once the melting temperature is exceeded. This can lead to manufacturing defects, especially undermining in the extrusion-blowing process or the breaking of the sections in the extrusion or in the spinning of fibers. The aim was to modify the partially crystalline partially aromatic polyesters so that their viscosity is markedly increased by retaining, or minimally modifying, however, the other properties of these polyesters, especially the partially crystalline nature of the synthetic material. The objective was achieved by the use of a copolymer of a) 60-98% by weight of methyl methacrylate b) 2-40% by weight of styrene, and in any case c) 0-20% by weight of maleic anhydride as the agent modifier for raising the melt viscosity of partially crystalline partially aromatic polyesters, except for poly-1,4-butylene terephthalate or its copolymers with a lower amount of aliphatic or aromatic dicarboxylic acids or an aliphatic polyol containing 1 - . 1-80% by weight of a filler reinforcing material in the form of metals, ceramics, silicates, quartz, glass or reinforcing carbon. The use according to the invention of the copolymer as a modifying agent (rheology modifier) enables an improved manufacture of partially crystalline partially aromatic polyesters, especially of polyethylene terephthalate and polybutylene terephthalate (excluding polybutylene terephthalate with reinforcing materials according to DE-OS 23 64 316), since its melt viscosity increases markedly. At the same time, the other positive properties of the polyesters are preserved, especially their partially crystalline nature. This is surprising, since, for example, pure polymethyl methacrylate with a solution viscosity in chloroform according to ISO 1628-6 with 50 ml / g has a significantly higher melt viscosity, around 800 Pas at 230. ° C / 5MPa, than that of the polymethyl methacrylate / styrene copolymers, only the desired effect is given in the application of the copolymers according to the invention. It is assumed that this is due to the mixing behavior of the polymer melts in the mixture. By using the copolymers as modifying agents for increasing the melt viscosity In accordance with the invention, a modified partially aromatic partially crystalline polyester also claimed is obtained. This is suitable for the manufacture of formed parts, especially parts manufactured with the blowing process. Partially aromatic partially crystalline polyester types according to the invention are understood as the condensation products of terephthalic acid with aliphatic diol components, such as, for example, ethylene glycol or 1,4-butadiol or mixtures of diols. Examples of these are polyethylene terephthalate and polybutylene terephthalate. The invention is especially suitable for polyethylene terephthalate and polybutylene terephthalate. Polybutylene terephthalate is especially preferred. Polyethylene terephthalate according to the invention is understood as meaning polymers consisting essentially of ethylene terephthalate units. These are polymers containing a minimum of 95, preferably a minimum of 98% by weight of ethylene terephthalate or more. The polyethylene terephthalates, if any, may also contain small parts of diol components such as, for example, butadiol. They may also contain inorganic fillers such as, for example, talc or fiberglass.

Mixtures may also be present with small amounts of, for example, 5 to 20% by weight of compatible polymers, such as polycarbonate and / or acrylonitrile / butadiene / styrene (ABS). Modifying agents for the elevation of the melt viscosity in partially crystalline partially aromatic polyesters. The polymers consisting of a) 60-98% by weight of methyl methacrylate b) 2-40% by weight of styrene, and optionally c) 0-20% by weight of maleic anhydride can be prepared in a manner known per se from monomers a), b) and c) by radical, anionic or group transfer polymerization. The polymerization can be carried out in bulk, suspension, emulsion or solution. For the preparation of mixtures of fusion modifiers with polybutylene terephthalate (PBT), it is possible, for example, to premix the polybutylene terephthalate as a granulate with the copolymer, present as a granulate or as a ground material in a slow-running mixer, such as For example, a drum mixer, a wobble mixer or a double chamber plow mixer. The premixes made in this way below are working hot mix equipment at the suitable temperatures, for example between 180 and 300 ° C, in kneaders or preferably in extruders, for example in simple or multiple worm extruders or in oscillating worm extruders and with cutting pins (for example the Fa. Buss kneader) to achieve the homogeneous mixture of the synthetic material. The radical polymerization of the monomers in the presence of polymerization initiators and, if necessary, in the presence of molecular weight regulators. The average molecular weight Mw (average weight) is between about 100,000 and 1,000,000, preferably between 150,000 and 500,000 and especially preferred between 200,000 and 400,000. The average molecular weight Mw can be determined for example by gel permeation chromatography or by the parasitic light method (see for example HFMark et al, Encyclopedia of Polymer Science and Engineering, 2nd Edition, Vol. 10, pages 1 ff, J Wiley, 1989) Rheology modifiers with a content of between 70 and 95% by weight, especially between 80 and 90% by weight of methyl methacrylate, from 5 to 30% by weight, especially from 10 to 20% by weight, are preferred. weight of styrene and, if appropriate, between 00 and 15% by weight of maleic anhydride. As a general rule, maleic anhydride can be dispensed with as a comonomer, especially in rheology modifiers with molecular weight greater than 180,000, preferably greater than 200,000. The content of other copolymerizable monomers such as, for example, alkyl (meth) acrylates with 2 to 8 carbon atoms in the alkyl radical of between 0 and 10% by weight, preferably a maximum of 5% by weight, is possible but not necessarily necessary . The other comonomers present in amounts of 0 to 10% by weight can be, for example, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, hexyl methacrylate, cyclohexyl acrylate or cyclohexyl methacrylate. Partially aromatic partially crystalline polyesters.

Partially aromatic partially crystalline polyesters are obtained by mixing with rheology modifiers. This is achieved in the simplest manner by premixing granules or ground material followed by extrusion. The mass thus obtained can be used directly or it can be granulated as a partly crystalline partially aromatic polyester. The amounts used for the rheology modifiers are in the range between 0.5 to 40% by weight, preferably between 2 and 35% by weight, based on the total weight of the mixture. The desired viscosity increase is already remarkable from about 0.5% by weight. Application amounts of from 5 to 35% by weight, especially from 10 to 35% by weight, and especially preferably from 15 to 35% by weight, are preferred. The processing of partially crystalline partially aromatic polyesters can in principle be carried out in the same way as with polyesters not modified by extrusion, injection, thermoforming, melt spinning or preferably by blowing. The usual working temperatures are between 250 and 29 ° C. The partially crystalline partially aromatic polyesters according to the invention can be worked particularly well at temperatures above the melting temperature, since they significantly increase the viscosity of the melt. Simultaneously the enthalpy of fusion, determined according to DSC (Differential Scanning Method, in this regard see Brandrup, J. and Immergut, EH, (1975): Polymer Handbook, III, pp. 144-148, Wiley, J.) as an indication of the Solvent resistance of the part of the corresponding mass, is preserved almost without modification. Especially in the blowing, where parts formed with a very homogeneous wall thickness are required, obvious advantages are achieved. The fusion of the tubes formed by extrusion has less tendency to deformation under the influence of the force of gravity. HE extends the tolerable temperature range in which preformed parts can be worked without depletion. This allows a reliable production and also allows the elevation of process temperatures and thus the pace of work, which leads to a better overall process economy.

EXAMPLES The invention is explained by the following examples, the results of which are summarized in Table 1: Example 1: Example of comparison with pure polybutyl terephthalate (PBT). Examples 2 - 5: Copolymer of 90% by weight of methyl methacrylate and 10% by weight of styrene. To a monomer mixture of 7200 g of methyl methacrylate and 800 g of styrene are added 16 g of dilauroyl peroxide as well as 4 g of 2,2-bis- (tert-butyl peroxy) butane as polymerization initiators and 28 g of n-dodecyl mercaptan as a molecular weight regulator. This solution is subjected, within a polymerization chamber, to a vacuum on dry ice for 25 minutes to free it as much as possible from the oxygenate. It is then polymerized for 5 hours in a water bath at 65 ° C and for 17 hours at 55 ° C. The product is tempered in a drying oven for 12 hours at 120 ° C for the final polymerization. The polymerizate has a viscosity of chloroform solution according to ISO 1628-6 of 66 ml / g. Examples 6-9: Copolymer of 90% by weight of methyl methacrylate and 10% by weight of styrene. The elaboration is carried out in a analogous to the procedure described above. 16 g of n-dodecyl mercaptan are added as a molecular weight regulator. The polymerization has a viscosity of chloroform solution according to ISO 1628-6 of 99 ml / g. Examples 10-13: Copolymer of 85% by weight of methyl methacrylate and 15% by weight of styrene. The processing is carried out analogously to the procedure described above. 28 g of n-dodecyl mercaptan are added as a molecular weight regulator. The polymerization has a viscosity of chloroform solution according to ISO 1628-6 of 77 ml / g. Examples 14-17: Copolymer of 85% by weight of methyl methacrylate and 15% by weight of styrene. The processing is carried out analogously to the procedure described above. 16.8 g of n- are added dodecyl mercaptan as a molecular weight regulator. The polymer has a viscosity of chloroform solution according to ISO 1628-6 of 105 ml / g. Copolymer of 90% by weight of methyl methacrylate and 10% by weight of styrene. The processing is carried out analogously to the procedure described above. 16 g of n-dodecyl mercaptan are added as a molecular weight regulator. The polymerization has a viscosity of chloroform solution according to ISO 1628-6 of 99 ml / g. Examples 18-21: Copolymer of 80% by weight of methyl methacrylate and 20% by weight of styrene. The processing is carried out analogously to the procedure described above. 28 g of n-dodecyl mercaptan are added as a molecular weight regulator. The polymerization has a viscosity of chloroform solution according to ISO 1628-6 of 77 ml / g. Examples 22-25: Copolymer of 80% by weight of methyl methacrylate and 20% by weight of styrene. The processing is carried out analogously to the procedure described above. 16 g of n-dodecyl mercaptan are added as a molecular weight regulator. He polymerized has a viscosity of chloroform solution according to ISO 1628-6 of 106 ml / g. Examples 26-29: Copolymer of 75% by weight of methyl methacrylate, 15% by weight of styrene and 10% by weight of maleic anhydride. The processing is carried out analogously to the procedure described above. 3.36 g of dilauroyl peroxide and 0.8 g of terbutyl perisononanoate are added as polymerization initiators and 13.4 g of 2-mercaptoethanol as a molecular weight regulator. The polymerization in a water bath is carried out for 6 hours at 60 ° C and 25 hours at 50 ° C. The polymerization has a viscosity of chloroform solution according to ISO 1628-6 of 65 ml / g. Table 1: Summary of the results of examples 1 to 29 Abbreviations: LV = viscosity of solution in chloroform according to ISO 1628-6 SRM = Fusion rheology modifier MA = Methyl methacrylate, SR = styrene, MSA = maleic anhydride

Claims (9)

1. Claims 1. Use of a copolymer of a) 60-98% by weight of methyl methacrylate b) 2-40% by weight of styrene, and in any case c) 0-20% by weight of maleic anhydride as a modifying agent for the increase in the melt viscosity of partially crystalline partially aromatic polyesters, with the exception of poly-1,4-butylene terephthalate or its copolymers with a lower amount of aliphatic or aromatic dicarboxylic acids or of an aliphatic polyol containing 1-80% by weight of a filling reinforcing material in the form of metals, ceramics, silicates, quartz, glass or reinforcing carbon.
2. 2. Use of a copolymer according to claim 1 as a modifying agent for increasing the melt viscosity for polybutylene terephthalate.
3. 3. Use of a copolymer according to claim 1 as a modifying agent for increasing the melt viscosity for polyethylene terephthalate.
4. 4. Use of a copolymer according to claim 1 in an amount between 0.5 and 40% by weight based on the polyester.
5. 5. A partially crystalline modified partially aromatic polyester, except poly-1,4-butylene terephthalate or its copolymers with a lesser amount of aliphatic or aromatic dicarboxylic acids or an aliphatic polyol containing 1-80% by weight of a filler reinforcing material in the form of metals, ceramics, silicates, quartz, glass or reinforcing carbon, characterized in that they contain an amount of copolymer between 0.5 and 40% by weight based on the polyester consisting of a) 60-98% by weight of methyl methacrylate b) 2-40% by weight of styrene, and optionally c) 0-20% by weight of maleic anhydride 6.
6. Modified polyester according to claim 5 characterized in that the polyester is polybutylene terephthalate.
7. Modified polyester according to claim 5, characterized in that the polyester is polyethylene terephthalate.
8. Piece formed of a modified polyester according to claim 5.
9. 9. Piece formed according to claim 8, characterized in that it is manufactured by the extrusion-blowing process.