CN101050273A - Method for producing polyester - Google Patents

Abstract

This invention discloses a method for producing low-viscosity polyester slices by melt-polymerization. The method comprises: soaking low-viscosity polyester slices in antioxidant solution, drying, and performing solid phase coincidence to obtain the product. The obtained polyester slices have good luster, good tint (b value), and high thermal stability. The diethylene glycol content is below 1.5, the heat-resistant index is below 1.1, and the melt specific resistance is (0.5-10)X10 to the power 8.

Description

Produce the method for polyester

Technical field:

The present invention relates to a kind of production method of polyester.

Background technology:

Polyester, particularly polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate, because its machinery, physics, chemical property excellence, characteristics such as, chemical-resistant reagent good, heat-resisting as physical strength, the transparency are good, many aspects now have been widely used in, as spinning short fiber, long filament, being used as wrapping material, electrically insulating material, sake and other layered products etc.But along with the expansion of its purposes and demand, the requirement strictness all the more that the characteristic of polyester is required and boosts productivity in each field.Many aspects such as that polyester film relates to is industrial, magneticsubstance is used and producing, but the problem that will solve is also a lot.

As the polymerizing catalyst of polyethylene terephthalate, antimony compounds is widely adopted, because they have excellent catalytic property to polymerization, and tool gained polyester has good color tone.When antimony compounds is used as polymerizing catalyst, when the gained polyester is implemented melt-spun continuously in the long time, the gained polyester has defective, tramp material adheres to and is accumulated in the melt-spun mouth of pipe, and cause that the polymer melt of extruding by the mouth of pipe bends, in melt-spun and drawing process, buckling phenomenon causes the formation and the melt-spun Si Tinkling breakage of fine hair, contaminate environment.

As the polyalcohol catalyst of non-antimony compounds, titanium compound is adopted in suggestion, when having adopted titanium compound, can solve the accumulation problem of mouth of pipe tramp material.Yet this catalyzer produces a new defective: gained polyester self tone flavescence also has relatively poor hot melt stability.

And, find after deliberation, in the process of producing polyester, in the fusion coincidence method, the rear half stage of coincidence, thermolysis is very strong.In order to reduce thermal decomposition process, adopt the method for solid phase coincidence, though conventional solid phase coincidence method has been improved tone, still, effect is still not obvious.

Summary of the invention:

The purpose of this invention is to provide a kind of stability that can improve polyester, made production method with the low polyester of good heat resistance and tone (b value) and foreign matter content

Technical solution of the present invention is:

A kind of method of producing polyester comprises that melt phase polycondensation makes the low-viscosity polyester section, is characterized in that: oxidation inhibitor solution immersion treatment is put in the low-viscosity polyester section, after with the low-viscosity polyester chip drying, further carried out solid phase and overlap processing, get product.

Described low-viscosity polyester section is meant that viscosity is 0.50～0.55 polyester slice.

Oxidation inhibitor solution is made up of oxidation inhibitor and solvent thereof, and oxidation inhibitor is phosphite ester compound or phosphorons acid compound, and wherein the structural formula of phosphite ester compound is:

R in the formula ₁, R ₂, R ₃, R ₄Be that carbon is 4～25 alkyl, cycloalkyl, arylalkyl or alkylaryl;

The general formula of phosphorons acid compound is as follows

R in the formula ₅, R ₆It is aryl radical.

The oxidation inhibitor solvent is its requirement of solvent, dissolved polyester, volatile solvents reaction for the discord phosphorous acid esters, can be acetone, ethanol or hexane etc.

The consumption relation extents of oxidation inhibitor and low viscosity section is 15ppm≤antioxygen dosage≤150ppm.

Advantage of the present invention is very tangible, and the polyester slice that obtains has color and luster, tone (b value) preferably, and thermostability is fine.Can make DEG (glycol ether) content and be 1.5 or below, heat-resistance index is 1.1 or following polyester.Can make fusion is 0.5 * 10 than resistance ⁸To 10 * 10 ⁸Between polyester.

The invention will be further described below in conjunction with embodiment:

Embodiment:

Embodiment 1:

A kind of method of producing polyester, detailed process is as follows:

The fusion coincidence method makes the low-viscosity polyester section: under 250 ℃ temperature, make 166 parts of (weight) terephthalic acids and 75 parts of (weight) ethylene glycol carry out the direct esterification reaction, the gained reaction product is placed the polymerization flask of being furnished with rectifying tower, and with as titanium content 5ppm in the chelating type titanium compound of the lactic acid of polymerizing catalyst, Mg content 10ppm in the magnesium oxalate compound, phosphorus content 13ppm among the phosphorons acid compound PEP36 (wherein addition is the addition with respect to weight polyester) mixes, under atmospheric pressure be decompressed to about 300Pa through one hour, temperature was warming up to 290 ℃ through one and a half hours, when described reaction is finished, temperature in the flask is 290 ℃, resulting pressure is about 200Pa, and the viscosity of gained polyester is about 0.55.

Section aftertreatment: the phosphorons acid compound 15ppm of oxidation inhibitor PEP36 is dissolved in acetone (or ethanol, the hexane) solution, the low viscous section 30g that makes is previously added in this solution, add while stirring, left standstill then 4 hours, after the similar solvent evaporates, reclaim section.Section after the recovery under 150 ℃ of vacuum states, dry about 7 hours.

Wherein the phosphorons acid compound of oxidation inhibitor is the compound (being called for short PEP36) of following structural formula

Solid phase coincidence method: in the developmental tube of (long 165mm * diameter 17mm Φ), put into the dried low-viscosity polyester section of 6g respectively, in 230 ℃ silicone oil bath, heat, take away small molecules, polycondensation is carried out by constantly small test tube inside being vacuumized.React after 8 hours, make viscosity and be about 0.665 section.

Embodiment 2:

Oxidation inhibitor adopts the phosphorons acid compound of following structural formula in the section aftertreatment:

The amount of phosphide is 30ppm in the section post treatment method

All the other conditions are identical with embodiment 1.

Embodiment 3:

Oxidation inhibitor adopts the phosphorons acid compound of following structural formula in the section aftertreatment:

The amount of phosphide is 6.5ppm in the fusion coincidence method

All the other conditions are identical with embodiment 1

Embodiment 4:

Antioxidant adopts phosphorons acid compound PEP36 in the section aftertreatment

The amount of phosphide is 150ppm in the section post treatment method

All the other conditions are identical with embodiment 1.

Embodiment 5:

Oxidation inhibitor adopts phosphite ester compound or phosphorons acid compound in the section aftertreatment, and wherein the structural formula of phosphite ester compound is:

R in the formula ₁, R ₂, R ₃, R ₄Be that carbon is 4～25 alkyl, cycloalkyl, arylalkyl or alkylaryl, concrete example R1, R2, R3, R4 can be 3-methyl-5-ethyl octane, 2,5-dimethyl-3,4-diethyl hexane, lauryl, hard ester group, 2,3,7-trimethylammonium-5-ethyl octane, 2,4-dibutyl phenyl, octyl phenyl, phenyl nonyl, phenyl dihydroxyphenyl propane, phenyl isodecyl etc.

The general formula of phosphorons acid compound is as follows

R in the formula ₅, R ₆It is aryl radical.

All the other are with embodiment 1.

[comparative example 1]

Being added to of catalyzer in the fusion coincidence method (with respect to the addition of weight polyester for)

The addition of antimony element is that the addition of phosphoric in 185ppm, the phosphoric acid is that the addition of magnesium elements in 16ppm, the magnesium compound is that the addition of potassium element in 60ppm, the potassium hydroxide is 4ppm in the antimonous oxide, and fusion directly reaches target viscosities 0.665 in overlapping.

All the other conditions are identical with embodiment 1.

There are not section last handling process, no solid phase coincidence process.

[comparative example 2]

Add phosphorons acid compound PEP36 in the fusion coincidence method

There is not the section last handling process

All the other conditions are identical with embodiment 1.

[comparative example 3]

Add phosphorons acid compound PEP36 in the fusion coincidence method

The experiment condition that fusion overlaps process is identical with embodiment 1, and fusion directly reaches target viscosities 0.665 in overlapping.

There are not section last handling process, no solid phase coincidence process.

[comparative example 4]

Being added to of catalyzer in the melting process (with respect to the addition of weight polyester for)

Titanium compound 5ppm, magnesium compound 10ppm, PEP36 phosphorus compound 28ppm, fusion directly reaches target viscosities 0.665 in overlapping.All the other conditions are identical with embodiment 1.

There are not section last handling process, no solid phase coincidence process.

Project	Fusion overlaps		Section aftertreatment P content ppm	Solid phase overlaps	The character of polyester				Stick to the height of melt-spun mouth of pipe tramp material layer on every side
										P content ppm	IV	IV	COOH (eq/ t)	The b value	The damaged number of main chain (equivalent/1000 kilogram)
	Embodiment 1	13			0.536	15	230℃×8hr	0.655								14	3.8	3.7	6
Embodiment 2			13	0.540					30	230℃×8hr	0.658	13	3.3	3.0	5
	Embodiment 3	6.5			0.543	15	230℃×8hr	0.663								15	4.1	3.2	7
Embodiment 4			13	0.540					150	230℃×8hr	0.660	12	2.9	2.5	5
	Comparative example 1	Sb adds			0.665	Do not have	Do not have	0.665								21	7.0	4.7	40
Comparative example 2			13	0.541					Do not have	230℃×8hr	0.657	17	6.5	6	7
	Comparative example 3	13			0.660	Do not have	Do not have	0.660								16	7.5	8	8
Comparative example 4			28	0.664					Do not have	Do not have	0.664	15	8.0	7	6

The measuring method of each index of the foregoing description 1～4, comparative example 1～3 is:

(1) limiting viscosity (IV) (dL/g)

With 0.5 gram polyester/milliliter phenol and sym.-tetrachloroethane etc. in the solution of weight mixture, in 25 ℃ of mensuration its limiting viscosities (IV) down

(2) melting heat stability

Polyester granules is put into 10 mm outer diameter of the nitrogen atmosphere that places 290 ℃, thus in the Glass tubing of 8 millimeters internal diameters, 250 mm lengths 15 minutes with its fusing.Before aforesaid thermal treatment and afterwards, measure the difference of the limiting viscosity of polyester granules.By the difference of limiting viscosity, the damaged number (equivalent) of the polyester molecule main chain of per 1000 kilograms of polyester polymers calculates according to following equation:

The damaged number of main chain (equivalent/1000 kilogram)

＝{[IV ₁/3.07*10 ^-4] ^-1.30-[IV ₀/3.07*10 ^-4] ^-1.30}*10 ^-6

In the equation, IV ₀Represent the limiting viscosity of the preceding polyester of thermal treatment, IV ₁Represent the limiting viscosity of polyester after the thermal treatment.

(3) carboxyl-content (COOH):

Adopt the optics titration measuring.Polyester is dissolved in the mixed solution (weight ratio 70: 30) of neighbour-cresols and chloroform, adds bromthymol blue indicator, carry out titration in the ethanolic soln with the potassium hydroxide of 0.05N then

(4) tone b value

Measure by GB GB/T 14190-1993.

Claims (4)

1, a kind of method of producing polyester, comprise that melt phase polycondensation makes the low-viscosity polyester section, is characterized in that: oxidation inhibitor solution immersion treatment is put in the low-viscosity polyester section, after with the low-viscosity polyester chip drying, further carry out solid phase and overlap processing, get product.

2, the method for production polyester according to claim 1 is characterized in that: described low-viscosity polyester section is meant that viscosity is 0.50～0.55 polyester slice.

3, the method for production polyester according to claim 1 and 2 is characterized in that: oxidation inhibitor solution is made up of oxidation inhibitor and solvent thereof, and oxidation inhibitor is phosphite ester compound or phosphorons acid compound, and wherein the structural formula of phosphite ester compound is:

R in the formula ₁, R ₂, R ₃, R ₄Be that carbon is 4～25 alkyl, cycloalkyl, arylalkyl or alkylaryl;

The general formula of phosphorons acid compound is as follows

R in the formula ₅, R ₆It is aryl radical.

4, the method for production polyester according to claim 3 is characterized in that: the oxidation inhibitor solvent is acetone, ethanol or hexane.