SU891699A1 - Method of producing modified polyethyleneterephthalate - Google Patents

Description

(54) METHOD FOR OBTAINING MODIFIED POLYETHYLENEERTEPHALATE

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This invention relates to the field of producing modified polyethylene terephthalate (PET), which is used to produce lavsan-type fiber, which has good dyeability of disperse dyes.

Synthetic polyester fiber based on PET has a high crystallinity and dense packing of polymer chains; as a result, the diffusion of the dye proceeds very slowly during the dyeing process, which makes it necessary to apply special dyeing methods — under pressure, at elevated temperature (120 s) or in the presence of carriers.

One of the promising methods for enhancing the dyeability of polyethylene terephthalate fiber is the chemical modification of PET in the process of its synthesis by introducing monomer units and blocks into the polyester chain, resulting in disruption of the crystal. the magnitude and regularity of the structure of macromolecules tl,

However, the strength characteristics of the fiber are usually reduced.

There is also known a method for producing PET-modified mono-epoxy compounds containing ethylene oxide groups.

The modifier is added at the stage of esterification and in the processing of the finished fiber, which leads to an improvement in dyeability of PET 2,

However, the mechanical properties of the fibers and the duration of the process are not long enough.

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The closest in technical essence and the achieved effect is a method for producing a modified polyethylene terephthalate by. Reacting terephthalic acid.

15 and ethylene glycol in the presence of an epoxy-containing modifier, followed by polycondensation of the obtained product.

The modifier is a monoepoxy compound of the general formula

20

;I.

R

25 where both R - CHOj or 5.

or one R N and the other is phenyl.

Fibers obtained on the basis of modified PET have an increased sorbing capacity according to

30 relative to the dispersed dye m 3.

However, the strength characteristics of the fibers are not long enough, and the duration of the polycondensation stage is 2.5 hours.

The purpose of the invention is to improve the physicomechanical properties of polyethylene orephthalate fiber while maintaining increased ability to sorb the dye and accelerate the polycondensation stage.

The goal is achieved by the fact that in the method of obtaining modified polyethylene terephthalate by reacting terephthalic acid and ethylene glycol in the presence of an epoxy-containing modifier with an aftercare Nets and a floor and condensing the resulting product, 1-5 mol.% Per mole of terephthalic acid is used as the epoxy-containing modifier,

where n 1,2

and the modifier is entered before the stage

polycondensation.

Unlike epoxy compounds that contain these enoxide groups, cycloaliphatic epoxy compounds containing epoxy groups per cycle have an increased reactivity with respect to carboxyl, and also react easily with hydroxyl groups and are more thermostable. The presence of a polar nitrile group capable of forming transverse physical bonds between

Macromolecules, should positively say on elasticity and elasticity.

. Modifying epoxy compound is obtained by epoxidation with peracetic acid, the corresponding unsaturated bicyclic natrilov - 2-nitrilbitsikloG2,2,1 5ena and hept-2-NitrilbitsikloG2,2, oct-2 5ena, is propelling adducts of acrylonitrile and cyclic dienes - cyclopentadiene and 1,3-tsiklogeksadiona.

The synthesis of modified PET samples is carried out in condensation glass tubes and in a steel laboratory autoclave at a molar ratio of terephthalic acid (TFA) and ethylene glycol 1: 4. The process is carried out in two stages. At the stage of esterification, the reaction mixture is heated at 190-195 ° C in an inert gas atmosphere while removing the liberated water, then the temperature is raised to 225-230 ° C and excess ethylene glycol is distilled off. The modifier is introduced before the polycondensation stage, which is carried out by heating the reaction mixture under vacuum, the heating time depends on the amount of modifier and is not more than 2 hours. From the obtained PET, the fibers are spun, and then subjected to 4 times at the temperature of the heating elements.

Mechanical properties are determined on a UMIV-3 installation with a sample clamping length of 25 mm, a monofilament diameter of 80-100 µm and a speed of stretching of 20 mm / min. Thermomechanical curves, which determine the glass transition temperature, melting point, and thermostability, are removed at this installation.

The determination of the dyeability of the modified fibers is carried out using a dispersed blue dye in an amount of 2% by weight of the fiber by heating in a boiling-water bath without carriers for 1.5 h with a bath modulus of 1:50. The amount of sorbed dye is calculated from the difference in the optical density of the bath before and after dyeing, determined on a FEK-56PM photocolorimeter using a calibration curve.

Example 1. Into a laboratory autoclave with a capacity of 0.5 l, 166 g (1 mol) of TFA, 225 MP (4 mol) of ethylene glycol, 0.4 ml of tetrabutoxy titanium as an esterification catalyst, 0.132 g of GeOj as a polycondensation catalyst, and 1 ml of triethanolamine are loaded. As a diethylene glycol formation inhibitor}, the reaction mixture is heated in a stream of N at 190 ° C to distill off 36 ml of water, increase the temperature to 220-230 ° C, inject 3 ml of a 15% strength solution of ethylene glycol as a heat stabilizer, and distill off the excess ethylene glycol. 4.1 g (3 mol.%) of 2-nitro-1-5,6-epoxybicyclo 2, 2.1 heptane are introduced into the reaction mixture, heated with stirring for 0.5 h in an inert atmosphere, then the system is gradually evacuated as the temperature rises to 260 ° C and hold at this temperature and a pressure of 1 mm for 1.5 hours

Example 2. The synthesis was carried out as in Example 1, in the presence of 4.5 g as a modifier (3 mol.% 2-nitrile-5,6-epoxybicycloG.2.2 octane and polycondensation duration 1 h 45 min.

Example 3. In a glass condensation tube, 16, b g TFA, 22.5 MP of ethylene glycol, 0.06 g of tetrabutoxy titan, g of GeO / j, and 0.1 ml of triethanolamine are placed, the tube is placed in an air bath with an electric heater, heated in a stream of argon at a bath temperature of 195-198 ° C. until distillation of 3.5 ml of condensation water, 0.2 MP of 15% is introduced at 225-230 ° and an excess of ethylene glycol is distilled off. Into the reaction mass are introduced g (1 mol.%) 2-nitrile-5,6-eroxybicof2. 2. 1 heptane, vyderzhivayut 0.5 h at 190-200s, the system is gradually evacuated when the temperature rises to, stand for 1 h at a pressure of 1 mm and get colorless modified PET with sO, 30, and so pl. 250-251 p. The fibers formed from the obtained PET adsorb 66% of the dye from the bath, unmodified fiber — 49.5%. Example 4. The synthesis was carried out as described in Example 3, using 0.15 g (1 mol.%) Of 2-nitrile-5.6 as a modifier. epoxybicyclo 2.2.1 heptane and a polycondensation stage duration of 0.5 h. PET is obtained having i sp, 24, and so pl. 256-257 ° C. Fibers formed from the obtained PET adsorb 89% of the dye from the bath. Example 5. Synthesis was carried out as described in Example 3, using 0.75 g (5 mol.%) As a modifier. 2-nitropyl-5,6-epoxy-cyclic of 2. 2. 23 heptane and the duration of the polycondensation stage 50 min. Get PET with a miracle of 0.26 and T.il. 253-255 ° C. Fibers molded from the obtained PET adsorb 95% of the dye from the bath. The physico-mechanical properties of poly (ethylene terephthalate) and fibers modified with epoxides of bicyclic nitriles are listed in the table. From the data and examples given in the table, it can be seen that PET samples modified with epoxy derivatives of bicyclic nitriles are suitable for forming fibers that have an improved dye sorption capacity and higher mechanical parameters than unmodified fibers. The use of these modifiers significantly reduces the stage of polycondensation in the preparation of PET. In addition, the use of a cycloaliphatic modifier does not cause the darkening of the final polyesterification products, despite the harsh conditions of polycondensation, and does not reduce the thermal stability of the resulting modified samples. This indicates the thermal stability of the monoepoxys compounds proposed as modifiers. When comparing the characteristics of the obtained modified fibers with the corresponding indicators for the known modified fiber, it can be seen that the tensile strength and the tensile elongation value of the modified fibers according to the proposed method are superior to those obtained by a known method. When using cycloaliphatic monoepoxy derivatives of bicyclic sodium, it is possible to shorten the polycondensation step; which is 0.5-2 hours depending on the amount of modifier, and according to a known method, the duration is 2.5 hours. Thus, the proposed method allows to improve the physicomechanical properties of polyethylene terephthalate fiber while maintaining an increased dye sorption ability and accelerate polycondensation stage.

Glass transition temperature, ° C

90

Melting point

254256

Specific viscosity (20 ° С, 0.5%, m-cresol)

g Density, g / cm

Fiber strength with

4.38 break, g / denier

Initial module, kg / mm

700

105

75

238

238240

0.25

0.31 1.34 1.34

4.73 4.1-4-, 6

5.97

940

800

Explosive elongation,%

The degree of sorption of the dye,%

The duration of the polycondensation stage, h

Temperature 5% weight loss, С

Table continuation

85

32

20

49.5

66

72

Deep tones

1.75

2.0

2.5

368

360

Claims (1)

Invention Formula The method of obtaining the modified polyethylene terephthalate by the interaction of - phthalic acid and ethylene glycol in the presence of an epoxy-containing device with a subsequent liquefaction of the obtained product, about tal and y and, with that, yiTO, in order to improve the physical-mechanical systems in order to improve the physical-mechanical processes. stumps of preservation of increased dye sorption capacity and acceleration of the polycondensation stage, use 1-5 mol.% per mole as epoxy-containing modifier