ES2261065B1 - COPOLIMEROS POLI (ETILENTEREFTALATO-CO-ETILEN NITROTEREFTALATO). - Google Patents

Abstract

Copolymers poly (ethylene terephthalate-co-ethylene nitroterephthalate). Transesterification of dimethyl terephthalate (DMT) and dimethyl nitroterephthalate (DMNT) with ethylene glycol at 190 ° C under nitrogen atmosphere and subsequent polycondensation at temperatures between 220 and 270 ° C under vacuum, with titanium tetrabutoxide catalyst (TBT) leads to random copolyesters containing quantities of ethylene nitroterephthalate units ranging between 5 and 100 mol% with average molecular weights in number between 4200 and 16300 and by weight between 10400 and 62200, glass transition temperatures between 82 and 88 ° C, melting temperatures between 180 and 248 ° C and high Thermal stability. The properties of these copolymers allow their use in applications at higher temperatures than poly (ethylene terephthalate) (PET) and more comfortable and economical processing at lower temperatures.

Description

Copolymers poly (ethylene terephthalate-co-ethylene nitroterephthalate).

Technical sector

Polyesters containing units aromatic have good mechanical, thermal and optical properties, and are used in a wide range of applications. Through calendering generates amorphous and transparent films and laminates, useful for coating, packaging and packaging. By injection-blown materials can be obtained biaxially oriented, crystalline and transparent, with a low oxygen and carbon dioxide permeability, suitable for the manufacture of carbonated beverage bottles and containers airtight Finally, these polyesters can be spun like fibers in the form of a continuous filament that are cut into pieces of Small length for textile applications.

State of the art

Since the earliest days of the development of poly (ethylene terephthalate) (PET), great efforts have been devoted to exploring varieties of this homopolymer in order to obtain products with the thermal properties conveniently modified without deterioration of their mechanical, optical and transport properties. Dickinson et al. (Dickinson, JT, Huggil, PW and Welch, JC, Brit. Pat . 590 451 , 1947; Whinfield, JR and Dickinson, JT, US 2,465,319, EI du Pont de Nemours and Co., 1949) were the first to describe and patent the obtaining of linear aromatic polyesters capable of forming continuous fibers. These are prepared by polycondensation of terephthalic acid, dimethyl terephthalate or acid dihalide with a glycol type HO (CH2) n OH with values of n between 2-10. On the other hand, the preparation of aromatic polyesters containing units derived from phenylene, diphenylene or naphthalene dicarboxylic acids was patented a few years later by Flory and Leutner (Flory, PJ and Leutner, FS, US 2,589,688, Wingfoot Corp., 1952) .

Edgar and Ellery, and Snyder (Edgar, OB and Ellery, E., J. Chem. Soc ., 1952, 2633; Snyder, MD, US 2,623,031, EI du Pont de Nemours and Co., 1952) describe the preparation of copolyesters PET elastics with linear dicarboxylic aliphatic acids. On the other hand, the condensation of terephthalic acid or dimethyl terephthalate with aromatic glycols
Ticos was patented by Fisher and Lincoln (Fisher, JW and Lincoln, J., Brit. Pat . 678,264 , British Celanese Ltd., 1952).

The preparation of PET copolymers with 1,4-cyclohexylene dihydroxymethyl was described by Kibler et al. (Kibler, CJ, Bell, A. and Smith, JG, US 2,901,466, Eastman Kodak Co., 1960); The resulting polyesters have both glass transition temperatures and melting temperatures lower than that of PET. PET copolymers containing isophthalate units also have thermal transitions lower than those of PET, as described by various authors (Ahroni, SM, Makromol. Chem ., 179 , 1978, 1867; Moore, RAP and Peters, RH , Tex. Res. J , 49 , 1979, 623; Berghmans, H., Govaerts, F. and Overberg, N., J. Polym. Sci., Polym. Phys. Ed ., 17 , 1979, 1251). In contrast, PET copolymers containing rigid units derived from naphthalenedicarboxylic acids have glass transition temperatures and thermal stability higher than those of PET and a melting behavior strongly dependent on the content of naphthalene units (Sun, YM, Shieh, JY. and Wang, CS, Eur. Polym. J. , 33 , 1997, 317). PET copolymers with poly (ethylene glycol) were first described by Coleman and shortly thereafter by Snyder and by Veena et al. (Coleman D., Brit. Pat . 682 866 , Imperial Chemical Industries Ltd., 1952; and J. Polym. Sci ., 14 , 1954, 15; Snyder, MD, US 2,744,087, EI du Pont de Nemours and Co., 1956; Veena, SM, Varma, IK and Varma, DS, Angew. Makromol. Chem ., 82 , 1979, 63). This family of copolyesters was initially investigated with the purpose of reducing the crystallinity of PET and favoring fiber dyeing. Subsequently, these copolymers were explored in order to modify the thermal properties (Reed, AM and Gilding, DK, Polymer , 22 , 1981, 499; Kenney, JF, Polym. Eng. Sci ., 8 , 1968, 216).

In the scientific or patent literature there is no background on PET copolymers containing nitroterephthalate units such as those that are the subject of this invention. However, Kint et al. They have described a whole series of new PET copolymers with 5-nitroisophthalate units (Kint, DPR, Martínez de Ilarduya, A. and Muñoz-Guerra, S., J. Polym. Sci .: Part A: Polym. Chem ., 38 , 2000, 1934). The objective pursued on this occasion is to obtain PET copolymers with melting temperatures lower than PET but with higher glass transition temperatures. In this way the processing of the polymer is favored in the transformation and its scope is expanded to benefits that require higher thermal levels of use.

Explanation of the invention. Object of the invention

Synthesis of PET copolymers from dimethyl terephthalate (DMT), dimethyl nitroterephthalate (DMNT) and ethylene glycol (EG) (Scheme I) and containing amounts of ethylene nitroterephthalate units ranging between 5 and 100% (mol ET / mol ENT). The copolymers obtained have temperatures of glass transition higher and melting temperatures lower than PET's, so they can be used at higher temperatures high and at the same time allow a more comfortable processing. The strategy followed in this invention is to introduce units nitroterephthalate in the PET chain, in controlled quantities to achieve the desired effect without deteriorating Significantly its structure.

Scheme I

one

Synthesis

Polymerization methods based on polycondensation of monomers in molten state in conditions that lead to the formation of linear polyesters. The transesterification reaction and subsequent polycondensation of DMT, DMNT, and EG, according to scheme I, is carried out at temperatures ranging between 190 and 260 ° C under atmosphere of nitrogen and vacuum, respectively. The reaction is activated with a organometallic catalyst (titanium tetrabutoxide, TBT), which it is added in concentrations below 0.7 mmol TBT per mol monomers The copolyesters obtained are purified by dissolving them in a mixture of trifluoroacetic acid and chloroform (1/9 v / v) and precipitating them on an excess of methanol.

The polyesters object of this invention are denominated PET_ {x} NT_ {y} being x / y the molar ratio (%) of ethylene terephthalate / ethylene nitroterephthalate present in these copolymers The chemical structure of the repetitive unit is the shown in Scheme I. Modifying the relationship in which find the DMT and DMNT comonomers in the feed adjusts The final composition of the copolymer. Table 1 lists the copolymers prepared from the feed compositions and the reaction conditions used in each case.

TABLE I Polymerization characteristics and weights Molecules of PETNT Copolymers

Polyester Composition TBT b Conditions of Pesos molecular initial ^ a reaction c [DMT] / [DMNT] T t [η] d M_ {n} e M_ {n} / M_ {w} ^ {f} PET 100/0 0.61 190; 270 300; 35 0.59 13,700 16,300 / 58,500 PET_95 NT5 {5} 95/5 0.63 190; 250 300; 25 0.51 10,100 9,900 / 48,500 PET_ {90} NT_ {10} 90/10 0.59 190; 240 300; twenty 0.54 11,400 13,000 / 47,600 PET_ {85} NT_ {15} 85/15 0.61 190; 235 300; 25 0.54 11,400 12,300 / 62,200 PET_80 NT_ {20} 80/20 0.62 190; 230 300; 30 0.42 6,700 9,200 / 34,600 PET_ {70} NT_ {30} 70/30 0.60 190; 225 300; 25 0.44 7,400 8,900 / 42,400 PET_50 NT_ {50} 50/50 0.58 190; 220 360; Four. Five 0.25 2,200 5,500 / 17,100 PET_25 NT_ {75} 25/75 0.61 190; 220 480; Four. Five 0.36 4,800 5,700 / 21,500 PENT 0/100 0.60 190; 220 480; 60 0.21 1,500 4,200 / 10,400 ^ a Relationship initial molar. b Mmol TBT catalyst / mol monomer. c Temperature (° C) and time (min) of the first and second step. d Intrinsic viscosity (dL g -1) obtained in DCA at 25 ° C ^ e Weight molecular number determined by viscosimetry (a = 0.47 and K = 67 x 10-4). f Average molecular weights in number and weight determined by CPG

The bis (hydroxyethyl) model compound BHENT nitroterephthalate are obtained by transesterification of the dimethyl nitroterephthalate (DMNT) with a high excess of ethylene glycol (EG), as shown in Scheme II. The reaction it is carried out at a temperature of 190 ° C under an atmosphere of nitrogen and with the addition of TBT.

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Scheme II

2

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Characterization

The results of the characterization of BHENT, a product that is not described in the literature, are the following: T f 96-97 ° C. FT-IR (KBr, cm -1): 3347, 1732, 1545, 1352, 1274, 1129, 1070; 1 H NMR (CDCl 3, ppm, δ): 1.87 (s, br, 2H, OH), 3.94 (m, 2H, ArC (2) COOCH 2 C H 2 OH ), 4.01 (m, 2H, ArC (5) COOCH 2 C H 2 OH), 4.50 (m, 2H, ArC (2) COOCH 2), 4.54 (m, 2H, ArC (5 ) COOCH2), 7.86 (d, 1H, ArC (3) H), 8.37 (dd, 1H, ArC (4) H), 8.59 (d, 1H, ArC (6) H); 13 C NMR (CDCl 3, ppm, δ): 60.8 (ArC (2) COOCH 2 C H 2 OH), 61.1 (ArC (5) COOCH 2 C H_ { 2} OH), 67.7 (ArC (5) OO C H 2), 68.4 (ArC (2) OOO C H 2), 125.1 (ArC (6)), 130.4 (ArC (3)), 131.2 (ArC (2)), 133.8 (ArC (4)), 133.9 (ArC (5)), 147.8 (ArC (1)), 163.9 (ArC (5) C OO), 164.7 (ArC (2) C OO) .

The new PETNT copolymers have been characterized by FT-IR, 1 H NMR and 13 C, gel permeability chromatography (GPC), calorimetry scanning differential (DSC), thermogravimetry (TGA) and diffraction X-ray of dust and fiber. The results of the characterization for each of the copolyesters of the series is They are included in Tables I, II, III and IV.

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TABLE II Composition and elementary analysis of the copolymers PETNT

Polyester Composition DEG c Elemental analysis d [X_ {T}] / [X_ {NT}] a [X_ {T}] / [X_ {NT}] b (%) C (%) H (%) N (%) PET 100/0 100/0 1.1 61.40 (62.51) 4.23 (4.20) - (-) PET_95 NT5 {5} 94.6 / 5.4 94.5 / 5.5 0.8 60.36 (61.79) 4.14 (4.12) 0.34 (0.36) PET_ {90} NT_ {10} 89.6 / 10.4 90.0 / 10.0 1.1 60.15 (61.08) 4.07 (4.05) 0.66 (0.71) PET_ {85} NT_ {15} 84.9 / 15.1 85.2 / 14.8 0.9 59.13 (60.39) 4.00 (3.98) 0.97 (1.06) PET_80 NT_ {20} 79.9 / 20.1 80.4 / 19.6 1.0 58.40 (59.71) 3.88 (3.91) 1.32 (1.39) PET_ {70} NT_ {30} 69.8 / 30.2 69.3 / 30.7 1.6 57.88 (58.41) 3.74 (3.77) 1.96 (2.04) PET_50 NT_ {50} 49.7 / 50.3 49.9 / 50.1 0.9 55.26 (55.96) 3.61 (3.52) 3.22 (3.26) PET_25 NT_ {75} 24.6 / 75.4 25.9 / 74.1 1.1 51.54 (53.17) 3.24 (3.24) 4.50 (4.65) PENT 0/100 0/100 1.2 50.37 (50.65) 2.95 (2.98) 5.63 (5.91) a Determined by 1 H NMR. b Determined by NMR of 13 C. C content of diethylene glycol (mol%) determined by 1 H NMR. d In brackets the analyzes are indicated Theorists

TABLE III Average length of sequences and degree of chance of the PETNTs

Polyester Composition Diadas (mol%) Average length Grade of random, chance, fate of the sequences X_ {T} X_ {NT} TET TENT NTENT n_ {T} n_ {NT} R PET_95 NT5 {5} 94.6 5.4 89.0 11.0 0 17.2 1.0 1.06 (89.5) (10.2) (0.3) (18.5) (1.1) (1.00) PET_ {90} NT_ {10} 89.6 10.4 80.8 18.3 0.9 9.9 1.1 1.01 (80.3) (18.6) (1.1) (9.6) (1.2) (1.00) PET_ {85} NT_ {15} 84.9 15.1 72.9 24.7 2.4 6.9 1.2 0.98 (72.1) (25.6) (2.3) (6.6) (1.2) (1.00) PET_80 NT_ {20} 79.9 20.1 64.0 33.6 3.4 4.9 1.2 1.03 (63.8) (32.1) (4.1) (5.0) (1.3) (1.00) PET_ {70} NT_ {30} 69.8 30.2 49.3 40.0 10.7 3.5 1.5 0.94 (48.7) (42.2) (9.1) (3.3) (1.4) (1.00) PET_50 NT_ {50} 49.7 50.3 25.3 49.2 25.5 2.0 2.0 0.98 (24.7) (50.0) (25.3) (2.0) (2.0) (1.00) PET_25 NT_ {75} 24.6 75.4 7.3 37.1 55.6 1.4 4.0 0.97 (6.1) (37.1) (56.8) (1.3) (4.1) (1.00) In brackets the calculated values for a distribution Bernoulliana.

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TABLE IV Thermal properties of the copolymers PETNT

Polyester T g a (° C) T_m b (ºC) ΔH_ {m} {b} (J g <-1>) T d c (ºC) T_d1d (ºC) T d2 d (° C) RW e (%) PET 80 258 47.1 404 - 431 16 PET_95 NT5 {5} 82 248 44.0 395 382 434 fifteen PET_ {90} NT_ {10} 82 235 26.3 396 386 437 18 PET_ {85} NT_ {15} 84 223 18.0 385 377 430 25 PET_80 NT_ {20} 84 214 12.6 372 378 435 27 PET_ {70} NT_ {30} 83 180 2.3 380 388 438 29 PET_50 NT_ {50} 81 - - 361 380 425 32 PET_25 NT_ {75} 85 - - 365 387 426 35 PENT 88 - - 354 377 420 38 ^ {a} \ begin {minipage} [t] {150mm} Glass transition temperature measured as the inflection point of the heating curve obtained by DSC at a heating rate of 30 ° C min -1 from a rapidly cooled sample of the melt. \ end {minipage} ^ {b} \ begin {minipage} [t] {150mm} Temperature of melting and heat of fusion obtained by DSC at a rate of heating of 10 ° C min -1 of the samples from synthesis. \ end {minipage} c Temperature at which a loss of 10% weight per TGA. d First and second thermal degradation step determined by TGA. e Remaining weight at 550 ° C determined by TGA

Description of the figures

The figures that are included by way of illustration They refer to PETNT copolymers. Figure I shows the FT-IR spectra obtained from the copolymer PET_50 NT_ {50} and the two PET and PENT homopolymers a room temperature with a spectrometer Perkin-Elmer 2000 and it represents the transmittance in% versus wave number in cm -1. The figure II shows the 1 H and 13 C NMR spectra respectively, obtained from a solution of the copolymer PET_70 NT30 in deuterated trifluoroacetic acid with a 300 MHz Bruker AMX spectrometer. Figure III shows the differential scanning calorimetry (DSC) curves of some copolymers and PET powder obtained at 10 ° C min -1 in a Pyris I calorimeter by Perkin Elmer and in which the heat absorption versus temperature in ºC. Figure IV shows the thermogravimetry (TGA) curve of the copolymer PET_70 NT30 powder registered at 10 ° C min -1 in a TMA 6 thermobalance from Perkin-Elmer under the atmosphere of  nitrogen in which the% of remaining sample weight is represented against the temperature. Figure V shows the diagram of X-ray diffraction of fiber recorded on flat film with Kα radiation, of copper length 0.154 nm wave with a chamber length of 30 mm.

An example of embodiment of the invention BHENT model compound

This model compound has been prepared to be able to correctly assign the signals of the NMR spectra of the PETNT copolymers. In a 250 mL flask equipped with a column Distillation introduces dimethyl nitroterephthalate (42.88 g; 0.18 mol), ethylene glycol (200 mL; 3.6 mol) and TBT catalyst (0.6% mol / mol DMNT). The mixture is kept under stirring for 5 hours. at 190 ° C continuously distilling the methanol produced in the reaction. Excess EG was removed by vacuum distillation at 70 ° C The reaction product was dissolved in hot water and by filtration the remaining oligomers will be separated insoluble. The accused solution was concentrated and allowed to crystallize. The final product was recrystallized from chloroform again, giving place to yellowish BHENT crystals.

PET_90 NT_ {10} copolymer

The polymerization reaction is carried out in a 100 mL flask equipped with a mechanical stirrer, inlet nitrogen and a distillation column. In said flask it introduce DMT, DMNT, EG, and TBT. The reaction mixture was heated to 190 ° C with stirring and under a stream of nitrogen and maintained with stirring for 5 hours by continuously distilling the methanol produced in the reaction.

Subsequently, the current was cut off nitrogen, gradually reducing the pressure to 0.5-1 mbar for 10 min. Subsequently rose the temperature at 240 ° C and was maintained for 20 min, eliminating by distillation ethylene glycol and other volatiles. Finally the reaction mixture was cooled to room temperature removing the vacuum with nitrogen flow to prevent possible degradation by oxidation of the copolymer.

The resulting polymer was dissolved in a mixture of trifluoroacetic acid and chloroform and precipitated over methanol cold, washing repeatedly with this precipitant and ether diethyl The polymer thus obtained was dried under vacuum at 55 ° C for 72 hours

Industrial applications

Containers for carbonated beverages, waters minerals, edible oils, juices, tea, isotonic drinks, wines and alcoholic beverages, detergents and cleaning supplies, cosmetic products, pharmaceuticals, sauces and others food, chemicals and lubricants, products for agricultural treatments

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

Other industrial applications are: tubes, profiles, frames, walls, construction, and products in general obtained by injection and extrusion.

Fibers for use in rope and textile.

Claims (10)

1. Process for preparing copolymers poly (co - ethylene etilentereftalato- nitrotereftatalo) (PETNT), characterized by the transesterification and subsequent polycondensation of DMT, DMNT and ethylene glycol. 2. PETNT copolymers, obtainable according to the method of claim 1, characterized in that they contain ET / ENT ratios ranging between 95/5 and 25/75 (mol / mol). 3. PETNT copolymers according to claim 2, characterized by a statistical distribution of those of the ET and ENT units along the polymer chain. 4. PETNT copolymers according to claim 2, characterized by a glass transition temperature ranging between 80 and 88 ° C, in all cases higher than that of the PET homopolymer. 5. Copolymers PET 95 NT 5, PET 90 NT 10, PET 85 NT 15, PET 80 NT 20 and PET 70 NT 30, according to the claim 2, characterized by a melting temperature between 248 and 180 ° C, lower than that of the PET homopolymer. 6. PETNT copolymers according to claim 2, characterized by a triclinic crystalline cell for crystalline copolymers, with the same crystalline parameters as those of PET. 7. Copolymers PET 50 NT 50 and PET 25 NT 75, according to claim 2, characterized by being amorphous. 8. PETNT copolymers according to claim 2, characterized by a decomposition temperature greater than 350 ° C. 9. Procedure for obtaining the compound BHENT model consisting of transesterification of DMNT and EG with titanium tetrabutoxide (TBT). 10. BHENT monomer, obtainable according to method of claim 9, which has application for the PETNT copolymer preparation.