ES2341216B1 - COPOLIMEROS POLI (ETILEN-CO-CICLOHEXANODIMETILEN TEREFTALATO) OBTAINED THROUGH COPOLYMERIZATION BY OPENING OF RING. - Google Patents

Abstract

Copolymers poly (ethylene-co-cyclohexanedimethylene) terephthalate) obtained by opening copolymerization of ring.

The polymerization reaction of cyclic oligomers of ethylene terephthalate and cyclohexanedimethylene terephthalate to
280 ° C under nitrogen atmosphere for 15 min. and a reaction catalyst such as antimony oxide (Sb 2} {3} {O_) permits obtaining, without emission of volatile, copolyesters poly (ethylene - co -ciclohexanodimetilén terephthalate) (PE_ {x} {y} C T) with degrees of chance between 0.77 and 0.97, weight average molecular weights between 24,000 and 44,000 and glass transition temperatures between 80 and 88 ° C. The melting temperatures range between 215 and 286 ° C, it being observed that copolymers with composition ranges between 70/30 and 50/50 (ethylene terephthalate / cyclohexanedimethylene terephthalate) turn out to be amorphous. Their thermal stability is high and comparable to that obtained by polycondensation reaction. The method of obtaining them makes them interesting for use in RIM reactive injection molding technologies as well as for obtaining nanocomposites in situ .

Description

Copolymers poly (ethylene - co -ciclohexanodimetilén terephthalate) obtained by ring opening copolymerization.

Technical sector

PET-derived copolyesters that contain varying percentages of cyclohexanedimethylene units They are high performance materials, with good properties Mechanical, thermal and optical and good chemical resistance. These copolyesters are used in a wide range of applications ranging from the field of packaging and packaging such as bottles for carbonated beverages or pharmaceutical containers up to its use as a substitute material for glass in the form of thick sheets or even in the manufacture of helmets for Mopeds On the other hand the good properties of PE_ {x} C_ {y} T copolyesters make them suitable materials for manufacture of nanocomposites with mechanical properties and barrier improved.

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State of the art

The copolyesters (PE x C y T) derived from PET and based on 1,4-cyclohexanedimethanol were developed by Eastman Chemical Co. (Turner SR J. Polym. Sci. Part A. Polym. Chem . 42 , 5847 -5852, 2004). In 1977, they sold a PET-derived copolymer containing approximately 30% mol of cyclohexanedimethylene units under the name of Kodar PETG 6763 copolyester. This copolymer was an amorphous material, transparent and with very good mechanical and optical properties. The method of obtaining this copolymer consists of a two-stage polycondensation process. In the first esterification stage, water or methanol is eliminated depending on whether the starting monomer is terephthalic acid (PTA) or if it is dimethyl terephthalate (DMT). This first stage is carried out at temperatures between 200 and 250 ° C depending on the monomer used. In the second stage, polycondensation, which is carried out at higher temperatures and under vacuum, is ethylene glycol the volatile product that is evacuated in greater proportion, whereby the oligomers increase their molecular size. The use of certain catalysts as well as specific polycondensation processes allows obtaining a material with good characteristics (Adams, VS; Hataway, JE; Roberts, KA US. Pat. 5,681,918, 1997. Weaver, MA; Pruett, WP; Rhodes , SD; Hilbert, SD; Parham, WW US Pat. 5,372,864, 1994, US Pat. 5,384,377,
nineteen ninety five).

In the literature there are several examples of polyesters and copolyesters that are obtained by ring opening polymerization of cyclic oligoesters (Tripathy AR; MacKnight WJ; Kukureka SN Macromolecules , 37 , 6793-6800, 2004. Hodge, P .; Yang, Z .; Ben-Haida A .; McGrail CS J. Mater. Chem . 10 , 1533-1537, 2000. Brunelle DJ in Cyclic Polymers , Second Edition, J. A: Semlyn (ed.), 2000, Kluwer Academic Publishers ( Netherlands), pp. 185-228, Wang YF US Pat. 6,420,048, 2001. Wilson, T .; Williamson, D. T Pat. WO2006053070, 2006). However, there is no work to describe the synthesis of PE x C y T copolymers by ring opening polymerization of their respective cyclic oligoesters. Nor is any work found that describes the obtaining of cyclic oligoesters obtained from the poly (cyclohexanedimethylene terephthalate) homopolymer (PCT). The objective is to obtain these copolymers via ring opening polymerization of their respective cyclic oligomers, which methodology would allow their use for obtaining nanocomposites in situ or reactive processing by compression, injection or extrusion.

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Explanation of the invention. Object of the invention

Obtaining of PE x C y T copolymers with different compositions from cyclic oligomers of PET ( c -PET) and PCT ( c -PCT) (scheme I). These cyclic oligomers are obtained by cyclodepolymerization reaction of their respective homopolyesters.

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Scheme I

one

Synthesis of the cyclic oligomers of poly (etlien terephthalate) ( c -PET)

A suspension of PET pellets (5.00 g 26.04 mmol) in o- dichlorobenzene (DCB) (200 mL) containing as catalyst dibutyl tin oxide (DBTO) (194 mg, 0.78 mmol, 3 mol%) is heated at reflux temperature (180 ° C) and maintained with vigorous stirring for 48 hours. Subsequently, the mixture is cooled to 60 ° C and the insoluble material fraction is filtered (1.2 g, 24%). The solution is evaporated to dryness at 70 ° C and reduced pressure. The residue (3.8 g, 76%) is dissolved in chloroform (CHCl3) and precipitated with ethyl ether. The powder precipitate is dissolved again in dichloromethane (DCM), the insoluble fraction being filtered, and the solution precipitated again with ethyl ether.

The cycles thus obtained are dried at 60 ° C under reduced pressure and are characterized by 1 H and 13 C NMR and mass spectrometry with EMS electrospray (Figure I). The results show excellent agreement with those reported in the literature (Hodge, P .; Yang, Z., Abderrazak, BHA, and McGrail, CS, J. Mater. Chem , 10 , 1533-1537, 2000. Bryant JJL; Semlyen , JA Polymer 38 , 2475-2482, 1977). As can be seen in Figure I, the cyclic oligomer that is in greater proportion is the trimer (m / z = 577.1).

Synthesis of the cyclic oligomers of poly (cyclohexanedimethylene terephthalate) ( c -PCT)

A suspension of a powder sample of poly (cyclohexanedimethylene terephthalate) (PCT) (5.21 g, 19.01 mmol) in trichlorobenzene (TCB) (190 mL) containing as DBTO catalyst (142 mg, is heated to reflux temperature (214 ° C) 0.57 mmol, 3% mol) and is maintained at this temperature with strong stirring for 7 days. Subsequently the solution is cooled to room temperature, the insoluble material being filtered (4.1 g, 78%). The solvent is evaporated at 80 ° C and reduced pressure. The final residue (1.11 g, 21.3%) is dissolved in chloroform and precipitated with ethyl ether. The precipitate is dissolved once more in dichloromethane, and again precipitated with ethyl ether, dried at 60 ° C and under reduced pressure (0.78 g, 15% by weight). These cyclic oligomers are characterized by 1 H and 13 C NMR and EMS (Figure II). As in the c -PET cycles, the cyclic oligomer that is in greater proportion is the trimer (m / z = 823.3). The results agree to some extent with the c- PCT oligomers obtained by dissolution esterification reaction of terephthaloyl dichloride with 1,4-cyclohexanedimethanol (Wan XH; Yang Y .; Tu HL; Huang L .; Tan S., Zhou QF , Turner SR, J. Polym. Sci. Polym. Chem ., 38 , 1828-1833, 2000).

Synthesis of the PE_ {x} C_ {T} copolymers

The copolyesters are prepared by ring opening polymerization reaction of a mixture of cyclic oligomers c -PET and c -PCT, as shown in Scheme I. The copolyesters object of this invention are referred to as PE x C y} T being x / y the molar ratio (%) of ethylene terephthalate / cyclohexanedimethylene terephthalate present in these copolymers. By modifying the relationship in which the cyclic oligomers c -PET and c -PCT are found in the feed, the final composition of the copolymer is adjusted.

Specifically, x moles of c -PET are mixed with y moles of c- PCT and 0.5% mol of catalyst (Sb2O3) and the mixture is dissolved in DCM at 10% w / v. The solution is evaporated slowly at room temperature and subsequently introduced into a desiccator for 24 hours. Subsequently, 3 g of the mixture is added in a three-mouth spherical flask provided with nitrogen inlet and outlet and magnetic stirring. The flask is heated to 280 ° C and the mixture is kept under stirring at this temperature for 15 min. under nitrogen atmosphere. In a first step, the fusion of oligomers that rapidly polymerize to give a viscous gel difficult to stir is observed. Subsequently, remove the flask from the thermal bath and cool to room temperature by passing a stream of nitrogen to prevent degradation. The reaction yield ranges from 90-95% obtaining the polymers as solid masses of white, transparent or yellowish colors depending on the composition of the copolymer. As the copolymer increases the composition in cyclohexanedimethylene units the hue becomes more
yellowish

Characterization of PE_x C_ {T} copolymers

The new PE x C and T copolymers have been characterized by 1 H and 13 C NMR techniques, gel permeability chromatography (GPC), differential scanning calorimetry (DSC) and thermogravimetry (TGA). The results of the characterization for each of the copolyesters of the series are shown in Tables I, II, III. The molecular weights obtained are relatively high, taking into account the methodology used for the synthesis, being above the values reported in the literature for the synthesis of similar polymers and copolymers using the same methodology (Wan XH; Yang Y .; Tu HL ; Huang L .; Tan S., Zhou QF, Turner SR, J. Polym. Sci. Polym. Chem ., 38 , 1828-1833, 2000). The compositions determined by 1 H NMR coincide practically with the feed compositions. The copolymers have degrees of chance between 0.74 and 0.97, depending on the composition, which indicates that they have small proportions of chain with block distribution of each of the repetitive units. Thermal analyzes of these polymers show how the copolymers with the compositions between 70/30 and 50/50 (ethylene terephthalate / cyclohexanedimethylene terephthalate) turn out to be amorphous. The T g thereof varies almost linearly with the composition between the PET (80 ° C) and PCT (88 ° C) values. Finally, the thermal stability of the copolymers decreases slightly as the composition of the copolymer increases in cyclohexanedimethylene units.

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TABLE I Polymerization characteristics and weights molecules of the PE x C y T copolymers

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TABLE II Composition, average sequence length and grade of chance of the PE_ {x} C_ {y} T

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TABLE III Thermal properties of the copolymers PE_ {x} C_ {y} T

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Description of the figures

The figures included by way of illustration refer to the cyclic oligomers c -PET and c -PCT as well as to the copolymers (PE x C y T) obtained by ring opening polymerization reaction thereof. Figures I and II show the EMS diagrams of the PET and PCT cycles respectively obtained by cyclodepolymerization reaction of the respective homopolymers. Both diagrams show how the presence of the cyclic trimer is the majority (m / z = 577.1 (c-PET) and m / z = 823.3 (c-PCT)). Figure III shows the 1 H NMR spectrum of PE 70 C 30 T performed on a mixture of CDCl 3 / TFA 9/1 in a Bruker AMX-300 (300 MHz) device, where all the signals corresponding to the different protons are assigned. Figure IV shows the 13 C NMR spectrum of the same copolymer performed under the same conditions, with the assignments of the different carbon signals. Figure V shows the 13 C NMR spectra of the entire series of copolymers in the region corresponding to the non-protonated aromatic carbon, which shows a split by the effect of the distribution of sequences at the level of dyads. Figure VI shows the thermogravimetries of the entire series of synthesized copolymers. The thermograms were recorded in a Perkin-Elmer TGA-6 thermobalance at 10 ° C min -1 under a nitrogen atmosphere in which the% of remaining sample weight versus temperature is represented. Finally, Figure VII shows the DSC thermograms of heating (a) and cooling (b) obtained in a Perkin Elmer Pyris I equipment of the entire series recorded from samples that have been previously melted.

An example of embodiment of the invention PE 70 C 30 T copolymer

The polymerization reaction is carried out in a 100 mL 3-mouth spherical flask equipped with a magnetic stirrer, nitrogen inlet and outlet. Previously 1.86 g of c -PET cyclic oligomers (9.7 mmol of ET units) are mixed with 1.14 g of c- PCT (4.2 mmol of CT units) and 0.02 g of Sb2O3 (0.07 mmol) and dissolve with 10 ml of DCM. The solvent is evaporated at room temperature and the mixture is placed in a desiccator for 24 hours under vacuum. Subsequently the mixture is introduced into the flask and said flask in turn is introduced into a thermostated bath at 280 ° C with magnetic stirring in which the polymerization reaction of the cyclic oligomers occurs for a period of 15 min. To prevent thermal and hydrolytic degradation, a small stream of nitrogen is passed. Subsequently, the flask is removed from the bath and the reaction mixture is cooled to room temperature, with a stream of nitrogen.

The copolymer thus obtained is characterized using the techniques of NMR, GPC, DSC and TGA.

Industrial applications

Containers for carbonated beverages, waters minerals, edible oils, juices, tea, isotonic drinks, wines and alcoholic beverages, detergents and cleaning supplies, cosmetic products, pharmaceutical and medical products, sauces and other foods, chemicals and lubricants, products for agricultural treatments and in general for all applications already developed for which PETG has been developed.

Films for food containers, video, photography, electrical and electronic applications, packaging special.

Other industrial applications are: canopies of bus stops, poster panels, protective screens for machines,

Lenticular, graphic arts and pieces with fusion soldier.

Claims (6)

1. Procedure for obtaining consisting copolymerization ring opening of cyclic oligoesters ethylene terephthalate and cyclohexanedimethylene terephthalate copolymers poly (ethylene - co -ciclohexanodimetilén tereftatalo) (PE_ {x} {y} C T). 2. PE x C y T copolymers, obtainable according to the method of claim 1, characterized in that they contain ET / CT ratios ranging between 90/10 and 10/90 (mol / mol). 3. PE x C y T copolymers, obtainable according to the method of claim 1, characterized by having a glass transition temperature ranging between 80 and 88 ° C. 4. Copolymers PE 90 C 10 T, PE 80 C 20 T, PE 30 C 70 T, PE 10 C 90 T, obtainable according to the method of claim 1, characterized by having a melting temperature between 252 and 215 ° C, lower than that of the PET and PCT homopolymers. 5. Copolymers PE 70 C 30 T and PE 50 C 50 T, obtainable according to the method of claim 1, characterized by being amorphous. 6. PE x C y T copolymers, obtainable according to the method of claim 1, characterized by having a decomposition temperature greater than 400 ° C.