CN108130616B

CN108130616B - High-strength polyester industrial yarn and preparation method thereof

Info

Publication number: CN108130616B
Application number: CN201711342003.3A
Authority: CN
Inventors: 杨大矛; 杨超明; 赵艳丽; 赵慧荣
Original assignee: Jiangsu Hengli Chemical Fiber Co Ltd
Current assignee: Jiangsu Hengli Chemical Fiber Co Ltd
Priority date: 2017-12-14
Filing date: 2017-12-14
Publication date: 2020-05-05
Anticipated expiration: 2037-12-14
Also published as: CN108130616A

Abstract

The invention relates to a high-strength polyester industrial yarn and a preparation method thereof, wherein modified polyester is subjected to solid phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding to prepare the high-strength polyester industrial yarn, the longitudinal height is kept unchanged during cooling, the cross section area of a slow cooling chamber is increased, and meanwhile, the temperature of the plate surface of a spinneret plate is kept in the slow cooling chamber in a heat preservation mode, wherein a molecular chain of the modified polyester comprises a terephthalic acid chain segment, a glycol chain segment and a dihydric alcohol chain segment with a branched chain, and the structural formula of the dihydric alcohol with the branched chain is as follows:

in the formula, R₁And R₂Each independently selected from linear alkylene having 1 to 3 carbon atoms, R₃Selected from alkyl with 1-5 carbon atoms, R₄The high-strength polyester industrial yarn is selected from alkyl with 2-5 carbon atoms, and the breaking strength of the prepared high-strength polyester industrial yarn is more than or equal to 8.1 cN/dtex. The method is simple and reasonable, and the prepared industrial yarn has the advantages of high breaking strength and good mechanical property.

Description

High-strength polyester industrial yarn and preparation method thereof

Technical Field

The invention belongs to the field of fiber preparation, and relates to a high-strength polyester industrial yarn and a preparation method thereof.

Background

Polyethylene terephthalate (PET) fibers have been developed rapidly since the advent due to their excellent properties, and their production has become the world's cap of synthetic fibers. The polyester fiber has a series of excellent performances such as high breaking strength, high elastic modulus, moderate resilience, excellent heat setting performance, good heat resistance, light resistance, acid resistance, alkali resistance, corrosion resistance and the like, and the fabric prepared from the polyester fiber has the advantages of good crease resistance, good stiffness and smoothness and the like, so the polyester fiber is widely applied to the fields of clothing, home textiles and the like.

However, in the polycondensation reaction for synthesizing ethylene terephthalate, especially in the case of linear high polymer, linear and cyclic oligomers are also associated due to high-temperature oxidative degradation, the cyclic oligomers are formed by the back-biting cyclization of the chain ends of macromolecules in the polycondensation stage, about 70% or more of the cyclic oligomers are cyclic trimers, and the cyclic trimers have the characteristics of easy aggregation, easy crystallization, high chemical and heat stability and the like, and the formation of the cyclic trimers has the following influence on the processing of polyester: (1) the spinning assembly can be blocked, and the service life of the melt filter and the assembly is influenced; (2) the fiber can be separated out in the process of heat setting and deposited on a heating roller, so that the friction force is increased and the heating is uneven; (3) the dyeing process takes the cyclic trimer as a center, so that the dye is gathered and adhered to the surface of the fiber, the phenomena of dye color points, spots, color flowers and the like appear on the surface of the fiber, the hand feeling and the color light of the fabric woven by the fiber are influenced, and meanwhile, the normal liquid flow velocity of a melt is limited by the cyclic oligomer filled with a pipeline and a valve, so that the fiber is unevenly dyed, and the reproducibility is poor; (4) the adhesive is adhered to the surface of the fiber, so that the winding is difficult, the phenomena of yarn breakage, uneven thickness and the like occur, the mechanical properties of the fiber such as breaking strength, breaking elongation and the like are influenced, and the product quality is seriously influenced.

Meanwhile, in the production process of the PET fibers, a slow cooling area is usually arranged, and the purpose is two: firstly, the strand silk is ensured not to be rapidly cooled after being discharged from a spinneret plate, so that the exterior of the strand silk is highly oriented due to rapid cooling, macromolecules are in a disordered state due to high temperature inside the strand silk, and the difference of the radial structure of the fiber is large, namely the so-called skin-core effect; secondly, a higher temperature of the spinneret surface is maintained, so that the filaments are smoothly discharged, the orifice bulking effect is normal, and the phenomenon of melt fracture to form weak filaments is avoided. The heating mode of the slow cooling zone mainly has two modes, both modes are active heating, firstly, as shown in figure 1, the heating medium of the box body is used for heating, once the spinning temperature is determined, the adjustment is generally not needed, the adjustment is passive, and the different application conditions are difficult to adapt; another heating method is shown in fig. 2, an electrical heating method is adopted for heating, the setting temperature can be higher than the box heat medium temperature, or lower than the box heat medium temperature, and the method is flexible, and can be set according to actual conditions, but the high temperature can aggravate the coking of the oligomer on the spinneret, if the temperature is reduced, such as the power is cut off and the heating is not carried out, because the heater is usually made of aluminum material with heavy quality and good heat transfer effect, a large amount of heat can be absorbed from the box, the heat medium is rapidly condensed around the outside of the assembly cavity, the heat is not supplemented enough, so that the temperature of the spinning assembly is reduced, the melt flow performance is obviously reduced, a large amount of broken filaments are reduced in the product, and the like, especially for the production of fibers with special-shaped cross sections, the perimeter of the orifice is obviously increased due to the special-shaped cross sections, the coke deposits, the filament breakage is generated in the high-speed running of the strand silk, the filament breakage is shown on the surface of a spinning cake in the form of broken filament reduction and the like, the broken filament causes great trouble for post-processing unwinding, the strength elongation of the filament bundle is influenced, which is the defect that the existing slow cooling zone needs to be avoided as much as possible in the production, besides the defect of a heating mode, the slow cooling zone in the prior art also has the fatal defect that the slow cooling zone is a cylindrical chamber, low polymer cannot escape quickly and smoothly, the low polymer is gathered in a high-temperature field and is bound to be largely coked on a spinneret plate to cause the blockage of the spinneret plate, the plate cleaning period is shortened, or the coking substances are attached around a spinneret hole to generate bent filaments, the appearance quality of a product is rapidly deteriorated, the broken ends are remarkably increased, the production efficiency is reduced, the labor intensity of workers is high, particularly, the normal production operation is seriously influenced by the remarkable performance on the production of, causing great waste of production cost.

With the increasing output of polyester fibers, the quality requirements of people on the fibers are increased, the fibers are often required to have excellent mechanical properties, for example, the fibers used for preparing automobile safety belts, household or clothes and the like need to have higher breaking strength, but the mechanical properties of the fibers are reduced due to the higher content of oligomers in the fibers prepared by the prior art, so that the fibers are uneven and are easy to generate broken filaments.

Therefore, the preparation of a high-quality fiber with good mechanical properties is a problem to be solved at present.

Disclosure of Invention

The invention aims to solve the problems of poor mechanical property and low quality of fibers in the prior art, and provides a high-strength polyester industrial yarn with good mechanical property and high quality. The introduction of the dihydric alcohol with the branched chain in the modified polyester reduces the cyclic oligomer generated in the side reaction of the polyester, reduces the cyclic oligomer on the surface of the fiber, reduces the phenomena of fiber breakage, uneven fiber thickness and the like of the fiber, reduces the influence of the cyclic oligomer on the mechanical properties of the fiber such as breaking strength, breaking elongation and the like, and improves the quality of the fiber; the cylindrical slow cooling chamber is changed into a rectangular column shape, so that the dissipation space of spinning oligomers is enlarged, the active heating type slow cooling area is changed into a non-heating heat preservation type, the aggregation quantity and the hardness degree of the oligomers on a high-temperature spinneret plate are reduced, the plate cleaning period of fibers with special-shaped sections is greatly prolonged, and the occurrence of broken filaments and floating filaments of the fibers is reduced by effectively controlling the temperature, so that the quality of the fibers is improved.

In order to achieve the purpose, the invention adopts the technical scheme that:

a high-strength polyester industrial yarn is made of modified polyester, a molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment and a dihydric alcohol chain segment with a branched chain, and the structural formula of the dihydric alcohol with the branched chain is as follows:

in the formula, R₁And R₂Each independently selected from linear alkylene having 1 to 3 carbon atoms, R₃Selected from carbon atomsAlkyl of a number of 1 to 5, R₄The carbon atom number is 2-5, and the purpose of carbon atom number limitation is as follows: because a branched chain structure and a long chain structure are introduced into the dihydric alcohol, the electronegativity of an alkoxy part is weakened, the number of carbon atoms of the branched chain structure is too small, the electronegativity influence on the alkoxy part is small, and the significance for reducing the generation of cyclic oligomers is not large; the too large number of carbon atoms of the branched chain structure can generate intermolecular entanglement and influence the distribution of molecular weight;

the breaking strength of the high-strength polyester industrial yarn is more than or equal to 8.1 cN/dtex. The fiber prepared by the invention has higher breaking strength, good uniformity and high full-curl rate.

As a preferred technical scheme:

the fineness of the high-strength polyester industrial yarn is 275-1100 dtex, the deviation rate of linear density is +/-1.5%, the CV value of breaking strength is less than or equal to 3.0%, the center value of elongation at break is 13.5-17.0%, the deviation rate of elongation at break is +/-1.5%, the CV value of elongation at break is less than or equal to 8.0%, the center value of elongation at 4.0cN/dtex load is 5.7-6.5%, the deviation rate of elongation at 4.0cN/dtex load is +/-0.8%, the dry heat shrinkage rate under the conditions of 177 ℃, 10min and 0.05cN/dtex is 4.3-9.3%, the network is 6 +/-2/m, and the oil content is 0.4-0.9%. The deviation rate of the elongation of the polyester industrial yarn under the load of 4.0cN/dtex is small, which shows that the uniformity of the product is good and the quality of the fiber is high.

According to the high-strength polyester industrial yarn, the content of cyclic oligomers in the modified polyester is less than or equal to 0.6 wt%, the amount of cyclic oligomers in the polyester prepared by the prior art is 1.5-2.1 wt%, and compared with the prior art, the generation amount of cyclic oligomers is remarkably reduced;

the number average molecular weight of the modified polyester is 20000-27000, the molecular weight distribution index is 1.8-2.2, the molecular weight of the modified polyester is higher, the molecular weight distribution is narrower, the spinning processing requirement can be met, and the preparation of fibers with excellent performance is facilitated;

the molar content of the dihydric alcohol chain segment with the branched chain in the modified polyester is 3-5% of that of the terephthalic acid chain segment, and the molar content of the dihydric alcohol chain segment with the branched chain in the modified polyester is lower, so that the excellent performance of the polyester is maintained;

the dihydric alcohol with a branch chain is 2-ethyl-2-methyl-1, 3-propanediol, 2-diethyl-1, 3-propanediol, 2-butyl-2-ethyl-1, 3-propanediol, 3-diethyl-1, 5-pentanediol, 4-diethyl-1, 7-heptanediol, 4-di (1, -methylethyl) -1, 7-heptanediol, 3-dipropyl-1, 5-pentanediol, 4-dipropyl-1, 7-heptanediol, 4-methyl-4- (1, 1-dimethylethyl) -1, 7-heptanediol, 3-methyl-3-pentyl-1, 6-hexanediol or 3, 3-dipentyl-1, 5-pentanediol.

The preparation method of the modified polyester comprises the following steps: uniformly mixing terephthalic acid, ethylene glycol and the dihydric alcohol with the branched chain, and then sequentially carrying out esterification reaction and polycondensation reaction to obtain modified polyester; the modified polyester comprises the following specific preparation steps:

(1) performing esterification reaction;

preparing terephthalic acid, ethylene glycol and the dihydric alcohol with the branched chain into slurry, adding a catalyst and a stabilizer, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure to 0.3MPa, the esterification reaction temperature is 250-260 ℃, and the esterification reaction endpoint is determined when the distilled amount of water in the esterification reaction reaches more than 90% of a theoretical value;

(2) performing polycondensation reaction;

and after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the negative pressure condition, stably pumping the pressure in the low vacuum stage from normal pressure to below 500Pa in 30-50 min at the reaction temperature of 260-270 ℃ for 30-50 min, then continuously pumping the vacuum to perform the polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to below 100Pa, controlling the reaction temperature to 275-285 ℃ and the reaction time to be 50-90 min, and thus obtaining the modified polyester.

In the step (1), the molar ratio of the terephthalic acid, the ethylene glycol and the branched diol is 1: 1.2-2.0: 0.03-0.06, the addition amount of the catalyst is 0.01-0.05% of the weight of the terephthalic acid, and the addition amount of the stabilizer is 0.01-0.05% of the weight of the terephthalic acid;

the catalyst is antimony trioxide, ethylene glycol antimony or antimony acetate, and the stabilizer is triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.

The invention also provides a method for preparing the high-strength polyester industrial yarn, which is characterized in that the high-strength polyester industrial yarn is prepared by performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester;

during cooling, the longitudinal height is kept unchanged, the cross-sectional area of the slow cooling chamber is increased, and meanwhile, the slow cooling chamber keeps the plate surface temperature of the spinneret plate in a heat preservation mode. In the prior art, a slow cooling chamber generally adopts a heating medium or electric heating mode to keep the plate surface temperature of a spinneret plate, and the heat preservation mode is adopted to replace the heating medium or electric heating mode, so that the energy is saved, the temperature of a slow cooling area is reduced, the coking degree of oligomers on the spinneret plate surface is effectively reduced, and the plate cleaning period is prolonged.

As a preferred technical scheme:

according to the method, the intrinsic viscosity of the modified polyester after solid-phase polycondensation tackifying is 1.0-1.2 dL/g, the intrinsic viscosity is a representation mode of the molecular weight of the modified polyester, the intrinsic viscosity of the modified polyester is too high, the processing temperature of the modified polyester is correspondingly increased, the product is easily thermally degraded, and the intrinsic viscosity of the modified polyester is too low, so that the strength and the performance required by the fiber are difficult to obtain; the spinneret cleaning period is prolonged by 35-45%, and the replacement period of the spinning assembly is more than or equal to 40 days. The spinning assembly has long replacement period and good product stability, reduces the production cost and improves the economic benefit.

In the method, the increasing of the cross-sectional area of the slow cooling chamber means that the cross section of the slow cooling chamber is changed from a circle to a rectangle on the premise of keeping the spinneret plate connected with the slow cooling chamber unchanged, the slow cooling chamber in the prior art is cylindrical, and the cross section is circular, and under the condition of keeping the spinneret plate connected with the slow cooling chamber unchanged, the rectangular area is increased greatly relative to the circular area, so that the volume of the slow cooling chamber is increased by about 50%, and the dissipation speed and the quantity of oligomers (associated with spinning) are greatly increased; the slow cooling chamber is formed by enclosing a heat insulation plate and spacers, the heat insulation plate is embedded and hung at the bottom of the spinning box body, a hollow chamber I is formed in the heat insulation plate, the spacers are inserted into the hollow chamber I to divide the heat insulation plate into a plurality of slow cooling chambers, a spinneret plate is arranged in each slow cooling chamber, the number of the spindle is distinguished by inserting the spacers, and mutual interference of silicon oil sprays during plate cleaning is avoided;

the heat insulation plate is a stainless steel plate filled with heat insulation materials capable of resisting temperature of more than 400 ℃, the thickness of the heat insulation plate is 30-50 mm, the wall thickness of the stainless steel plate is 0.9-1.5 mm, the wall thickness of the stainless steel plate is as small as possible on the premise of ensuring no deformation, and the self heat absorption capacity and the load of a box body heating medium are reduced;

the heat-insulating material is rock wool or ceramic fiber, the heat-insulating material is not limited to the two materials, and other materials with similar functions can also be suitable for the invention;

the thickness of the spacer is 1-3 mm, and the thickness of the spacer is as thin as possible under the condition of ensuring the strength;

the plurality of spinneret plates in the hollow cavity I are circular spinneret plates, the diameters of the plurality of spinneret plates are the same, and the circle centers of the plurality of spinneret plates are positioned on the same straight line and are closely adjacent;

the cross section of the hollow cavity I is rectangular, the side parallel to the connection line of the circle centers of the plurality of spinneret plates is a long side, and the side perpendicular to the long side is a short side;

the length of the long side is 1.2 times of the sum of the diameters of the spinneret plates, and the length of the short side is 1.7 times of the diameter of the spinneret plate.

According to the method, the heat insulation plate is superposed below the heat insulation plate, the material of the heat insulation plate is the same as that of the heat insulation plate, the heat insulation plate is internally provided with the hollow cavity II, and the cross sections of the hollow cavity II and the hollow cavity I are the same in shape;

in the position where the hollow cavity II is communicated with the hollow cavity I, two edges of the cross section of the hollow cavity II coincide with two short edges of the cross section of the hollow cavity I respectively, and the length of the two edges is larger than the two short edges, so that the hollow cavity II and the hollow cavity I form a step after the thermal insulation plate and the thermal insulation plate are stacked, and oligomers are easy to diffuse;

the thickness of the heat insulation plate is 25-45 mm.

In order to obtain high-quality fibers with good mechanical properties, the method adjusts relevant process parameters in the preparation process, and the adjusted spinning process parameters of the high-strength polyester industrial yarns are as follows:

the technological parameters of stretching and heat setting are as follows:

the invention mechanism is as follows:

in organic compounds, the angle between two chemical bonds formed by the same atom in a molecule is called the bond angle, which is usually expressed in degrees, and the electronegativity of the central atom and the coordinating atom in the molecule of the organic compound affects the bond angle of the molecule. When the electronegativity of the coordinating atom bonded to the central atom is increased, the electron-withdrawing ability of the coordinating atom is increased, the bonding electron pair moves toward the ligand and is farther away from the central atom, so that the bond pairs are closer to each other due to the decrease in repulsive force, and the bond angle is decreased, and conversely, when the electronegativity of the coordinating atom bonded to the central atom is decreased, the electron-donating ability of the coordinating atom is increased, the bonding electron pair moves toward the central atom and is closer to the central atom, so that the bond pairs are farther away from each other due to the increase in repulsive force, and the bond angle is increased.

According to Pauling electronegativity scale, the electronegativity of C, H and O atoms are 2.55, 2.20 and 3.44, respectively, and according to valence electron energy equilibrium theory, the calculation formula of the group electronegativity is shown as follows:

in the formula, x_iIs the electronegativity of the neutral atom of the i atom before bonding, N_ve，iIs the number of valence electrons in the i atom, n_iIs the number of i atoms in the molecule. The calculation steps for the electronegativity of more complex groups are mainly: the electronegativity of the simple group is firstly calculated, then the electronegativity of the more complex group is calculated by taking the simple group as a quasi atom, and the electronegativity of the target group is finally obtained through successive iteration. In calculating the electronegativity of a quasi-atom, the valence electron that is not bonded in a radical atom (for example, the radical atom of a group-OH is an O atom) is regarded as the valence electron of the quasi-atom.

In the invention, C atoms are combined with O atoms of hydroxyl groups in dihydric alcohol to form new C-O bonds in ester groups after C-O bonds of carboxyl groups in terephthalic acid are broken, bond angles between C-C bonds formed by the C atoms in the ester groups and C atoms on a benzene ring and the newly formed chemical bonds C-O are recorded as α, the change of the bond angle α influences the ring forming reaction, when α is less than 109 ℃, molecules are easy to form rings, and the ring forming probability of the molecules is reduced along with the increase of α.

In the formula, R₁And R₂Each independently selected from linear alkylene having 1 to 3 carbon atoms, R₃Selected from alkyl with 1-5 carbon atoms, R₄Selected from C2E to C5 alkyl group. The diol structure is introduced with a branched chain structure and a long chain structure, so that the electronegativity of an alkoxy part of the diol structure is weakened, and the electronegativity of a group connected with a carbonyl group in diacid in the diol structure is 2.59-2.79 according to a calculation formula of the electronegativity of the group, and a group-OCH (OCH) group connected with the carbonyl group in the diacid in ethylene glycol₂CH₂Electronegativity of-was 3.04, so that the alkoxy group was in comparison with-OCH in ethylene glycol₂CH₂The carbon fiber has stronger electron donating property, so that bond-forming electron pairs on newly formed chemical bond C-O bonds move towards the central C atom and are closer to the central atom, the bond angles α are larger than 109 degrees due to the increase of repulsive force, the probability of generating linear polymers is increased, the generation of cyclic oligomers is reduced, the phenomena of fiber surface cyclic oligomers, such as fiber breakage, fiber thickness unevenness and the like are reduced, the influence of the cyclic oligomers on mechanical properties such as the breaking strength and the breaking elongation of fibers is reduced, and the product quality is improved.

According to the invention, under the condition of keeping the longitudinal height unchanged, the cross section of the slow cooling chamber is changed from the conventional round shape to the rectangular shape, so that the cross section area of the slow cooling chamber is increased, the dissipation space of spinning oligomer is enlarged, and meanwhile, the heat preservation mode of the slow cooling chamber is changed from an active heating type to a non-heating heat preservation type, so that the energy consumption is reduced, and the aggregation number and the hardness degree of the oligomer on a high-temperature spinneret plate are reduced. Through the improvement of the two aspects, the invention greatly prolongs the cleaning period of the fiber with the special-shaped section. In addition, the hollow heat insulation plate can be stacked under the heat insulation plate, so that the hollow cavities in the heat insulation plate and the heat insulation plate can form a step after the heat insulation plate and the heat insulation plate are stacked, on one hand, the length of a windless area is prolonged, on the other hand, the diffusion speed of the oligomer is accelerated, and meanwhile, the heat insulation effect can be achieved. The cross section area of the slow cooling chamber is increased, on one hand, oligomers in the fibers can be further diffused into the air, the performance of the fibers is improved, on the other hand, the probability that the diffused oligomers are retained on the spinneret plate is reduced, the cleaning period of the spinneret plate is reduced, the temperature of the plate surface of the spinneret plate is kept in the slow cooling chamber in a warm keeping mode, the generation of a broken filament phenomenon is further reduced, the cleaning period of the spinneret plate and the generation of broken filaments are reduced, the quality of products is improved, and the production cost is reduced.

Has the advantages that:

(1) the high-strength polyester industrial yarn is simple and reasonable in preparation method, high in breaking strength and good in mechanical property, and has good market popularization value;

(2) according to the preparation method of the high-strength polyester industrial yarn, the cylindrical slow cooling chamber is changed into the rectangular column shape, the dissipation space of spinning oligomers is enlarged, the active heating type slow cooling area is changed into the non-heating heat preservation type, the aggregation number and the hardness degree of the oligomers on a high-temperature spinneret plate are reduced, and the cleaning period of fibers with special-shaped sections is greatly prolonged;

(3) the preparation method of the high-strength polyester industrial yarn greatly improves the production efficiency, reduces waste yarn, improves the spinning quality and reduces the labor intensity of workers;

(4) according to the preparation method of the high-strength polyester industrial yarn, the dihydric alcohol with the branched chain is introduced into the modified polyester, so that the bond angle of polyester molecules is changed, and the generation of cyclic oligomers in the polyester synthesis process is remarkably reduced.

Drawings

FIG. 1 is a schematic view of a prior art cylindrical slow cooling zone heated with a gaseous heating medium;

FIG. 2 is a schematic diagram of a cylindrical slow cooling zone using electric heating in the prior art;

FIG. 3 is a schematic view of a square slow cooling zone of the invention adopting an insulation board for heat preservation;

the method comprises the following steps of 1-spinning beam, 2-gas phase heating medium in the spinning beam, 3-hollow chamber I, 4-electric heater, 5-hollow chamber II, 6-insulation board and 7-insulation board.

Detailed Description

The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Example 1

A preparation method of high-strength polyester industrial yarn comprises the following specific steps:

(1) preparing modified polyester:

(a) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 2-ethyl-2-methyl-1, 3-propanediol with a molar ratio of 1:1.2:0.03 into slurry, adding antimony trioxide and triphenyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure, the esterification reaction temperature is 250 ℃, and the esterification reaction end point is when the distilled amount of water in the esterification reaction reaches 90% of a theoretical value, wherein the adding amount of the antimony trioxide is 0.01% of the weight of the terephthalic acid, the adding amount of the triphenyl phosphate is 0.05% of the weight of the terephthalic acid, and the structural formula of the 2-ethyl-2-methyl-1, 3-propanediol is as follows:

(b) performing polycondensation reaction; after the esterification reaction is finished, starting the polycondensation reaction in the low vacuum stage under the condition of negative pressure, smoothly pumping the pressure from normal pressure to the absolute pressure of 500Pa within 30min, controlling the reaction temperature to be 260 ℃ and the reaction time to be 40min, then continuing to pump the vacuum, and carrying out the polycondensation reaction in the high vacuum stage to further reduce the reaction pressure to the absolute pressure of 100Pa, control the reaction temperature to be 275 ℃ and control the reaction time to be 70min, thus obtaining the modified polyester. Wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, a glycol chain segment and a 2-ethyl-2-methyl-1, 3-propanediol chain segment, the content of cyclic oligomer in the modified polyester is 0.6 wt%, the number average molecular weight is 20000, the molecular weight distribution index is 2.0, and the molar content of the 2-ethyl-2-methyl-1, 3-propanediol chain segment in the modified polyester is 3% of the molar content of the terephthalic acid chain segment;

(2) the modified polyester is subjected to solid phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.02 dL/g; the replacement period of the spinning assembly is 40 days, the period for cleaning the spinneret is prolonged by 39 percent, the dipping solution of the first bath in the two-bath dipping method is D-417, and the dipping solution of the second bath is RFL. During cooling, the longitudinal height is kept unchanged, the cross-sectional area of the slow cooling chamber is increased, meanwhile, the slow cooling chamber keeps the plate surface temperature of the spinneret plate in a heat preservation mode, the structural schematic diagram of the slow cooling chamber is shown in figure 3, the heat preservation plate 6 is hung at the bottom of the spinning manifold 1 in an embedded mode, a gas-phase heat medium 2 is arranged in the spinning manifold 1, the heat preservation plate 6 is hollow in a shape like a Chinese character 'hui', a hollow chamber I3 is arranged in the hollow chamber I, the cross section of the chamber is rectangular, the side parallel to the circle center connecting line of the spinneret plates is taken as the long side direction, the length of the long side is 1.2 times of the sum of the diameters of the spinneret plates, the direction perpendicular to the long side is taken as the short side direction, the length of the short side is 1.7 times of the diameter of the spinneret plates, a spacer with the thickness of 1mm is inserted into the hollow chamber. The diameters of the spinneret plates are the same, and the centers of the circles of the spinneret plates are positioned on the same straight line and are closely adjacent. The heat insulation board 6 is a stainless steel plate filled with rock wool which can resist the temperature of 400 ℃, the thickness of the heat insulation board 6 is 30mm, and the wall thickness of the stainless steel plate is 0.9 mm. A heat insulation plate 7 with the thickness of 25mm is stacked below the heat insulation plate 6, the material of the heat insulation plate 7 is the same as that of the heat insulation plate 6, a hollow cavity II 5 is formed in the heat insulation plate 7, and the cross sections of the hollow cavity II 5 and the hollow cavity I3 are the same; the long sides of the cross sections of the hollow chamber II 5 and the hollow chamber I3 are the same in length; at the position where the hollow chamber II 5 is communicated with the hollow chamber I3, two edges of the cross section of the hollow chamber II 5 are respectively superposed with two short edges of the cross section of the hollow chamber I3, and the lengths of the two edges are greater than the two short edges. Wherein the rectangular column slow cooling district that corresponds single circular spinneret adopts the heated board to keep warm, the embedded suspension of heated board is in the bottom of spinning box, be equipped with well plenum chamber I in the heated board, the heat insulating board superposes down the heated board, well plenum chamber II has been seted up in the heat insulating board, wherein in the position of well plenum chamber II with well plenum chamber I intercommunication, two limits of well plenum chamber II cross section coincide with two minor faces of well plenum chamber I cross section respectively, and the length on these two limits is greater than two minor faces, cavity chamber II forms a step with well plenum chamber I after the stack of two boards in order to accelerate the oligomer diffusion.

The spinning process parameters of the high-strength polyester industrial yarn are shown in table 1.

The performance parameters of the finally prepared high-strength polyester industrial yarn are shown in table 2.

Example 2

(1) preparing modified polyester:

(a) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 2, 2-diethyl-1, 3-propanediol with a molar ratio of 1:1.3:0.04 into slurry, adding ethylene glycol antimony and trimethyl phosphate, uniformly mixing, and pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure, the esterification reaction temperature is 260 ℃, and the esterification reaction end point is when the water distillation amount in the esterification reaction reaches 91% of a theoretical value, wherein the adding amount of the ethylene glycol antimony is 0.02% of the weight of the terephthalic acid, the adding amount of the trimethyl phosphate is 0.03% of the weight of the terephthalic acid, and the structural formula of the 2, 2-diethyl-1, 3-propanediol is as follows:

(b) performing polycondensation reaction; after the esterification reaction is finished, starting the polycondensation reaction in the low vacuum stage under the condition of negative pressure, smoothly pumping the pressure from normal pressure to absolute pressure of 490Pa within 35min, controlling the reaction temperature to 261 ℃ and the reaction time to 30min, then continuing to pump the vacuum, and carrying out the polycondensation reaction in the high vacuum stage, so that the reaction pressure is further reduced to absolute pressure of 100Pa, the reaction temperature is 277 ℃ and the reaction time is 85min, thus obtaining the modified polyester. Wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, a glycol chain segment and a 2, 2-diethyl-1, 3-propanediol chain segment, the content of cyclic oligomer in the modified polyester is 0.6 wt%, the number average molecular weight is 27000, the molecular weight distribution index is 1.8, and the molar content of the 2, 2-diethyl-1, 3-propanediol chain segment in the modified polyester is 5% of the molar content of the terephthalic acid chain segment;

(2) and (3) performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.12 dL/g; the replacement period of the spinning assembly is 42 days, the period for cleaning the spinneret is prolonged by 40 percent, the dipping solution of the first bath in the two-bath dipping method is D-417, and the dipping solution of the second bath is RFL. During cooling, the longitudinal height is kept unchanged, the cross-sectional area of the slow cooling chamber is increased, the temperature of the plate surface of the spinneret plate is kept by the slow cooling chamber in a heat preservation mode, the structure of the slow cooling chamber is basically the same as that of embodiment 1, the difference is that the thickness of the spacer is 2mm, the heat preservation material filled in the heat preservation plate is ceramic fiber, the heat resistance temperature of the heat preservation plate is 405 ℃, the thickness of the heat preservation plate is 40mm, the wall thickness of the stainless steel plate is 1.2mm, and the thickness of the heat preservation plate is 35.

Example 3

(1) preparing modified polyester:

(a) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 2-butyl-2-ethyl-1, 3-propanediol with a molar ratio of 1:1.4:0.05 into slurry, adding antimony acetate and trimethyl phosphite, uniformly mixing, and then pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.1MPa, the esterification reaction temperature is 252 ℃, the esterification reaction end point is when the distilled water amount in the esterification reaction reaches 92% of a theoretical value, the adding amount of the antimony acetate is 0.03% of the weight of the terephthalic acid, the adding amount of the trimethyl phosphite is 0.01% of the weight of the terephthalic acid, and the structural formula of the 2-butyl-2-ethyl-1, 3-propanediol is as follows:

(b) performing polycondensation reaction; after the esterification reaction is finished, the polycondensation reaction in the low vacuum stage is started under the condition of negative pressure, the pressure is smoothly pumped from normal pressure to the absolute pressure of 495Pa within 40min, the reaction temperature is 263 ℃, the reaction time is 45min, then continuously vacuumizing, carrying out polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to 95Pa absolute, 278 ℃ reaction temperature and 60min reaction time, preparing modified polyester, wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, a glycol chain segment and a 2-butyl-2-ethyl-1, 3-propanediol chain segment, the content of cyclic oligomer in the modified polyester is 0.5 wt%, the number average molecular weight is 21000, the molecular weight distribution index is 2.2, and the molar content of the 2-butyl-2-ethyl-1, 3-propanediol chain segment in the modified polyester is 4% of the molar content of the terephthalic acid chain segment;

(2) and (3) performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.10 dL/g; the replacement period of the spinning assembly is 48 days, the period for cleaning the spinneret is prolonged by 44%, the dipping solution of the first bath in the two-bath dipping method is D-417, and the dipping solution of the second bath is RFL. During cooling, the longitudinal height is kept unchanged, the cross-sectional area of the slow cooling chamber is increased, the temperature of the plate surface of the spinneret plate is kept by the slow cooling chamber in a heat preservation mode, the structure of the slow cooling chamber is basically the same as that of embodiment 1, the difference is that the thickness of the spacer is 3mm, the heat preservation material filled in the heat preservation plate is rock wool, the heat resistance temperature of the heat preservation plate is 410 ℃, the thickness of the heat preservation plate is 50mm, the wall thickness of the stainless steel plate is 1.5mm, and the thickness of the heat preservation plate is.

Example 4

(1) preparing modified polyester:

(a) preparing 3, 3-diethyl-1, 5-pentanediol; reacting 3, 3-diethyl-propionaldehyde, acetaldehyde and triethylamine for 20min at 90 ℃ in a nitrogen atmosphere, then adding the concentrated solution into a hydrogenation reactor with a Raney nickel catalyst, reacting at a hydrogen pressure of 2.914MPa and a temperature of 100 ℃, cooling after the reaction is finished, separating out the catalyst, treating the solution with ion exchange resin, evaporating water under reduced pressure, separating and purifying to obtain 3, 3-diethyl-1, 5-pentanediol, wherein the structural formula of the 3, 3-diethyl-1, 5-pentanediol is as follows:

(b) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 3, 3-diethyl-1, 5-pentanediol with the molar ratio of 1:1.5:0.06 into slurry, adding antimony trioxide and triphenyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.3MPa, the temperature of the esterification reaction is 255 ℃, and the end point of the esterification reaction is determined when the distilled amount of water in the esterification reaction reaches 95% of a theoretical value, wherein the adding amount of the antimony trioxide is 0.04% of the weight of the terephthalic acid, and the adding amount of the triphenyl phosphate is 0.01% of the weight of the terephthalic acid;

(c) performing polycondensation reaction; after the esterification reaction is finished, the polycondensation reaction in the low vacuum stage is started under the condition of negative pressure, the pressure is stably pumped from normal pressure to the absolute pressure of 400Pa within 50min, the reaction temperature is 265 ℃, the reaction time is 33min, then continuously vacuumizing, carrying out polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to 90Pa absolute, the reaction temperature is 280 ℃, the reaction time is 50min, preparing modified polyester, wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment and a 3, 3-diethyl-1, 5-pentanediol chain segment, the content of cyclic oligomers in the modified polyester is 0.2 wt%, the number average molecular weight is 23000, the molecular weight distribution index is 1.9, and the molar content of the 3, 3-diethyl-1, 5-pentanediol chain segment in the modified polyester is 3.5% of the molar content of the terephthalic acid chain segment;

(2) and (3) performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.18 dL/g; the replacement period of the spinning assembly was 44 days, the period for cleaning the spinneret was extended by 35%, the dipping solution of the first bath in the two-bath dipping method was D-417, and the dipping solution of the second bath was RFL. During cooling, the longitudinal height is kept unchanged, the cross-sectional area of the slow cooling chamber is increased, the temperature of the plate surface of the spinneret plate is kept by the slow cooling chamber in a heat preservation mode, the structure of the slow cooling chamber is basically the same as that of the slow cooling chamber in embodiment 1, the difference is that the thickness of the spacer is 1.5mm, the heat preservation material filled in the heat preservation plate is ceramic fiber, the heat resistance temperature of the heat preservation plate is 402 ℃, the thickness of the heat preservation plate is 35mm, the wall thickness of the stainless steel plate is 1.0mm, and the thickness of the.

Example 5

(1) preparing modified polyester:

(a) preparing 4, 4-diethyl-1, 7-heptanediol; reacting 4, 4-diethyl-butyraldehyde, propionaldehyde and triethylamine for 20min at 92 ℃ in a nitrogen atmosphere, then adding the concentrated solution into a hydrogenation reactor with a Raney nickel catalyst, reacting at a hydrogen pressure of 2.914MPa and a temperature of 100 ℃, cooling after the reaction is finished, separating out the catalyst, treating the solution with ion exchange resin, evaporating water under reduced pressure, separating and purifying to obtain 4, 4-diethyl-1, 7-heptanediol, wherein the structural formula of the 4, 4-diethyl-1, 7-heptanediol is as follows:

(b) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 4, 4-diethyl-1, 7-heptanediol with a molar ratio of 1:1.6:0.03 into slurry, adding ethylene glycol antimony and trimethyl phosphate, uniformly mixing, and pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure, the esterification reaction temperature is 257 ℃, and the esterification reaction end point is when the water distillation amount in the esterification reaction reaches 92% of a theoretical value, wherein the adding amount of the ethylene glycol antimony is 0.05% of the weight of the terephthalic acid, and the adding amount of the trimethyl phosphate is 0.04% of the weight of the terephthalic acid;

(c) performing polycondensation reaction; after the esterification reaction is finished, the polycondensation reaction in the low vacuum stage is started under the condition of negative pressure, the pressure is stably pumped from normal pressure to the absolute pressure of 450Pa within 33min, the reaction temperature is 270 ℃, the reaction time is 30min, then continuously vacuumizing, carrying out polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to 95Pa absolute, the reaction temperature to 275 ℃, and the reaction time to 60min to obtain modified polyester, wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, a glycol chain segment and a 4, 4-diethyl-1, 7-heptanediol chain segment, the content of cyclic oligomers in the modified polyester is 0.5 wt%, the number average molecular weight is 25000, the molecular weight distribution index is 2.1, and the molar content of the 4, 4-diethyl-1, 7-heptanediol chain segment in the modified polyester is 5% of the molar content of the terephthalic acid chain segment.

(2) And (3) performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.0 dL/g; the replacement period of the spinning assembly was 49 days, the period for cleaning the spinneret was extended by 36%, the dipping solution of the first bath in the two-bath dipping method was D-417, and the dipping solution of the second bath was RFL. During the cooling, keep vertical height unchangeable, increase the cross-sectional area of slow cooling cavity, the slow cooling cavity adopts the heat retaining mode to keep the face temperature of spinneret simultaneously, and slow cooling cavity structure is the same basically with embodiment 1, and the difference lies in that it only has the heated board, does not superpose the heat insulating board under the heated board.

Example 6

(1) preparing modified polyester:

(a) preparing 4, 4-di (1-methylethyl) -1, 7-heptanediol; reacting 4, 4-di (1-methylethyl) -butyraldehyde, propionaldehyde and triethylamine for 20min at 95 ℃ under the nitrogen atmosphere, then adding the concentrated solution into a hydrogenation reactor with a Raney nickel catalyst, reacting at the hydrogen pressure of 2.914MPa and the temperature of 100 ℃, and cooling to separate out the catalyst after the reaction. After the solution is treated by ion exchange resin, water is evaporated under reduced pressure, and the 4, 4-di (1-methylethyl) -1, 7-heptanediol is separated and purified, wherein the structural formula of the 4, 4-di (1-methylethyl) -1, 7-heptanediol is as follows:

(b) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 4, 4-di (1-methylethyl) -1, 7-heptanediol with the molar ratio of 1:1.7:0.05 into slurry, adding antimony acetate and trimethyl phosphite, uniformly mixing, and pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.2MPa, the temperature of the esterification reaction is 253 ℃, and the end point of the esterification reaction is determined when the distilled amount of water in the esterification reaction reaches 96% of a theoretical value, wherein the adding amount of the antimony acetate is 0.01% of the weight of the terephthalic acid, and the adding amount of the trimethyl phosphite is 0.05% of the weight of the terephthalic acid;

(c) performing polycondensation reaction; after the esterification reaction is finished, the polycondensation reaction in the low vacuum stage is started under the condition of negative pressure, the pressure is stably pumped from normal pressure to the absolute pressure of 480Pa within 38min, the reaction temperature is 262 ℃, the reaction time is 38min, then continuously vacuumizing, carrying out polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to 98Pa absolute, the reaction temperature to 279 ℃, and the reaction time to 80min to obtain modified polyester, wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, a glycol chain segment and a 4, 4-di (1-methylethyl) -1, 7-heptanediol chain segment, the content of cyclic oligomer in the modified polyester is 0.55 wt%, the number average molecular weight is 27000, the molecular weight distribution index is 2.2, and the molar content of the 4, 4-di (1-methylethyl) -1, 7-heptanediol chain segment in the modified polyester is 4% of the molar content of the terephthalic acid chain segment;

(2) and (3) performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.0 dL/g; the replacement period of the spinning assembly is 40 days, the period for cleaning the spinneret is prolonged by 41 percent, the dipping solution of the first bath in the two-bath dipping method is D-417, and the dipping solution of the second bath is RFL. During the cooling, keep vertical height unchangeable, increase the cross-sectional area of slow cooling cavity, the slow cooling cavity adopts the heat retaining mode to keep the face temperature of spinneret simultaneously, and slow cooling cavity structure is the same basically with embodiment 2, and the difference lies in that it only has the heated board, does not superpose the heat insulating board under the heated board.

Example 7

(1) preparing modified polyester:

(a) preparing 3, 3-dipropyl-1, 5-pentanediol; reacting 3, 3-dipropyl-propionaldehyde, acetaldehyde and triethylamine for 20min at 94 ℃ in a nitrogen atmosphere, then adding the concentrated solution into a hydrogenation reactor with a Raney nickel catalyst, reacting at the hydrogen pressure of 2.914MPa and the temperature of 100 ℃, cooling after the reaction is finished, and separating out the catalyst. After the solution is treated by ion exchange resin, water is evaporated under reduced pressure, and the 3, 3-dipropyl-1, 5-pentanediol is separated and purified, wherein the structural formula of the 3, 3-dipropyl-1, 5-pentanediol is as follows:

(b) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 3, 3-dipropyl-1, 5-pentanediol with the molar ratio of 1:1.8:0.03 into slurry, adding antimony trioxide and triphenyl phosphate, uniformly mixing, and pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.3MPa, the esterification reaction temperature is 250 ℃, and the esterification reaction end point is the end point of the esterification reaction when the distilled amount of water in the esterification reaction reaches 90% of a theoretical value, wherein the adding amount of the antimony trioxide is 0.03% of the weight of the terephthalic acid, and the adding amount of the triphenyl phosphate is 0.02% of the weight of the terephthalic acid;

(c) performing polycondensation reaction; after the esterification reaction is finished, the polycondensation reaction in the low vacuum stage is started under the condition of negative pressure, the pressure is smoothly pumped from normal pressure to the absolute pressure of 455Pa within 42min, the reaction temperature is 264 ℃, the reaction time is 45min, then continuously vacuumizing, carrying out polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to 85Pa absolute, the reaction temperature to 285 ℃, the reaction time to 75min, preparing modified polyester, wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment and a 3, 3-dipropyl-1, 5-pentanediol chain segment, the content of cyclic oligomers in the modified polyester is 0.45 wt%, the number average molecular weight is 26500, the molecular weight distribution index is 2.2, and the molar content of the 3, 3-dipropyl-1, 5-pentanediol chain segment in the modified polyester is 4.5% of the molar content of the terephthalic acid chain segment.

(2) And (3) performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.2 dL/g; the replacement period of the spinning assembly was 41 days, the period for cleaning the spinneret was extended by 44%, and the dipping solution in the first bath was D-417 and the dipping solution in the second bath was RFL in the two-bath dipping method. During the cooling, keep vertical height unchangeable, increase the cross-sectional area of slow cooling cavity, the slow cooling cavity adopts the heat retaining mode to keep the face temperature of spinneret simultaneously, and slow cooling cavity structure is the same basically with embodiment 3, and the difference lies in that it only has the heated board, does not superpose the heat insulating board under the heated board.

Example 8

(1) preparing modified polyester:

(a) preparing 4, 4-dipropyl-1, 7-heptanediol; reacting 4, 4-dipropyl-butyraldehyde, acetaldehyde and triethylamine for 20min at 92 ℃ in a nitrogen atmosphere, then adding the concentrated solution into a hydrogenation reactor with a Raney nickel catalyst, reacting at the hydrogen pressure of 2.914MPa and the temperature of 100 ℃, cooling after the reaction is finished, and separating out the catalyst. Treating the solution with ion exchange resin, evaporating water under reduced pressure, separating, and purifying to obtain 4, 4-dipropyl-1, 7-heptanediol, wherein the structural formula of the 4, 4-dipropyl-1, 7-heptanediol is as follows:

(b) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 4, 4-dipropyl-1, 7-heptanediol with the molar ratio of 1:1.9:0.04 into slurry, adding ethylene glycol antimony and trimethyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.3MPa, the esterification reaction temperature is 260 ℃, and the esterification reaction end point is the end point when the distilled amount of water in the esterification reaction reaches 93% of a theoretical value, wherein the adding amount of the ethylene glycol antimony is 0.04% of the weight of the terephthalic acid, and the adding amount of the trimethyl phosphate is 0.03% of the weight of the terephthalic acid;

(c) performing polycondensation reaction; after the esterification reaction is finished, the polycondensation reaction in the low vacuum stage is started under the condition of negative pressure, the pressure is stably pumped from normal pressure to the absolute pressure of 475Pa within 45min, the reaction temperature is 265 ℃, the reaction time is 48min, then continuously vacuumizing, carrying out polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to 88Pa absolute, 283 ℃ reaction temperature, and 80min reaction time to obtain modified polyester, wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, a glycol chain segment and a 4, 4-dipropyl-1, 7-heptanediol chain segment, the content of cyclic oligomer in the modified polyester is 0.6 wt%, the number average molecular weight is 23000, the molecular weight distribution index is 2.0, and the molar content of the 4, 4-dipropyl-1, 7-heptanediol chain segment in the modified polyester is 3% of the molar content of the terephthalic acid chain segment;

(2) and (3) performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.15L/g; the replacement period of the spinning assembly was 44 days, the period for cleaning the spinneret was extended by 45%, the dipping solution of the first bath in the two-bath dipping method was D-417, and the dipping solution of the second bath was RFL. During the cooling, keep vertical height unchangeable, increase the cross-sectional area of slow cooling cavity, the slow cooling cavity adopts the heat retaining mode to keep the face temperature of spinneret simultaneously, and slow cooling cavity structure is the same basically with embodiment 4, and the difference lies in that it only has the heated board, does not superpose the heat insulating board under the heated board.

Example 9

(1) preparing modified polyester:

(a) preparing 4-methyl-4- (1, 1-dimethylethyl) -1, 7-heptanediol; reacting 4-methyl-4- (1, 1-dimethylethyl) -butyraldehyde, propionaldehyde and triethylamine for 20min at 92 ℃ in a nitrogen atmosphere, then adding the concentrated solution into a hydrogenation reactor with a Raney nickel catalyst, reacting at a hydrogen pressure of 2.914MPa and a temperature of 100 ℃, cooling after the reaction is finished, separating the catalyst out, treating the solution with ion exchange resin, evaporating water under reduced pressure, separating and purifying to obtain 4-methyl-4- (1, 1-dimethylethyl) -1, 7-heptanediol, wherein the structural formula of the 4-methyl-4- (1, 1-dimethylethyl) -1, 7-heptanediol is as follows:

(b) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 4-methyl-4- (1, 1-dimethylethyl) -1, 7-heptanediol with the molar ratio of 1:2.0:0.05 into slurry, adding antimony acetate and trimethyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure MPa, the esterification reaction temperature is 251 ℃, and the esterification reaction end point is determined when the water distillation amount in the esterification reaction reaches 96% of a theoretical value, wherein the adding amount of the antimony acetate is 0.05% of the weight of the terephthalic acid, and the adding amount of the trimethyl phosphate is 0.04% of the weight of the terephthalic acid;

(c) performing polycondensation reaction; after the esterification reaction is finished, starting the polycondensation reaction in the low vacuum stage under the condition of negative pressure, smoothly pumping the pressure from normal pressure to the absolute pressure of 420Pa within 30min, the reaction temperature is 267 ℃, the reaction time is 50min, then continuing to pump the vacuum, carrying out the polycondensation reaction in the high vacuum stage, further reducing the reaction pressure to the absolute pressure of 80Pa, the reaction temperature is 280 ℃, and the reaction time is 90min, thus obtaining the modified polyester, wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, a glycol chain segment and a 4-methyl-4- (1, 1-dimethylethyl) -1, 7-heptanediol chain segment, the content of cyclic oligomer in the modified polyester is 0.25 wt%, the number average molecular weight is 24000, the molecular weight distribution index is 2.2, and the 4-methyl-4- (1, 1-dimethylethyl) -1 in the modified polyester, the molar content of the 7-heptanediol chain segment is 4 percent of the molar content of the terephthalic acid chain segment;

(2) the modified polyester is subjected to solid phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.09 dL/g; the replacement period of the spinning assembly is 45 days, the period for cleaning the spinneret is prolonged by 35 percent, the dipping solution of the first bath in the two-bath dipping method is D-417, and the dipping solution of the second bath is RFL. During cooling, the longitudinal height is kept unchanged, the cross-sectional area of the slow cooling chamber is increased, the temperature of the plate surface of the spinneret plate is kept by the slow cooling chamber in a heat preservation mode, the structure of the slow cooling chamber is basically the same as that of embodiment 1, the difference is that the thickness of the spacer is 3mm, the heat preservation material filled in the heat preservation plate is rock wool, the heat resistance temperature of the heat preservation plate is 410 ℃, the thickness of the heat preservation plate is 50mm, the wall thickness of the stainless steel plate is 1.5mm, and the thickness of the heat preservation plate is.

Example 10

(1) preparing modified polyester:

(a) preparing 3-methyl-3-pentyl-1, 6-hexanediol; reacting 3-methyl-3-pentyl-propionaldehyde, propionaldehyde and triethylamine for 20min at 90 ℃ in a nitrogen atmosphere, then adding the concentrated solution into a hydrogenation reactor with a Raney nickel catalyst, reacting at the hydrogen pressure of 2.914MPa and the temperature of 100 ℃, cooling after the reaction is finished, and separating out the catalyst. After the solution is treated by ion exchange resin, water is evaporated under reduced pressure, and the 3-methyl-3-pentyl-1, 6-hexanediol is obtained through separation and purification, wherein the structural formula of the 3-methyl-3-pentyl-1, 6-hexanediol is as follows:

(b) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 3-methyl-3-pentyl-1, 6-hexanediol with a molar ratio of 1:1.2:0.06 into slurry, adding ethylene glycol antimony and trimethyl phosphite, uniformly mixing, and pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.1MPa, the esterification reaction temperature is 255 ℃, and the esterification reaction end point is the end point when the distilled water amount in the esterification reaction reaches 92% of a theoretical value, wherein the adding amount of the ethylene glycol antimony is 0.01% of the weight of the terephthalic acid, and the adding amount of the trimethyl phosphite is 0.01% of the weight of the terephthalic acid;

(c) performing polycondensation reaction; after the esterification reaction is finished, the polycondensation reaction in the low vacuum stage is started under the condition of negative pressure, the pressure is stably pumped from normal pressure to the absolute pressure of 490Pa within 50min, the reaction temperature is 269 ℃, the reaction time is 30min, then continuously vacuumizing, carrying out polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to 100Pa absolute, the reaction temperature to 281 ℃, the reaction time to 55min, preparing modified polyester, wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment and a 3-methyl-3-amyl-1, 6-hexanediol chain segment, the content of cyclic oligomer in the modified polyester is 0.1 wt%, the number average molecular weight is 20000, the molecular weight distribution index is 1.9, and the molar content of the 3-methyl-3-amyl-1, 6-hexanediol chain segment in the modified polyester is 3.5 percent of the molar content of the terephthalic acid chain segment;

(2) and (3) performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.1 dL/g; the replacement period of the spinning assembly is 42 days, the period for cleaning the spinneret is prolonged by 35 percent, the dipping solution of the first bath in the two-bath dipping method is D-417, and the dipping solution of the second bath is RFL. During the cooling, keep vertical height unchangeable, increase the cross-sectional area of slow cooling cavity, the slow cooling cavity adopts the heat retaining mode to keep the face temperature of spinneret simultaneously, and slow cooling cavity structure is the same basically with embodiment 1, and the difference lies in that it only has the heated board, does not superpose the heat insulating board under the heated board.

Example 11

(1) preparing modified polyester:

(a) preparing 3, 3-diamyl-1, 5-pentanediol; reacting 3, 3-diamyl-propionaldehyde, acetaldehyde and triethylamine for 20min at 95 ℃ in a nitrogen atmosphere, then adding the concentrated solution into a hydrogenation reactor with a Raney nickel catalyst, reacting at the hydrogen pressure of 2.914MPa and the temperature of 100 ℃, and cooling to separate out the catalyst after the reaction is finished. After the solution is treated by ion exchange resin, water is evaporated under reduced pressure, and the 3, 3-diamyl-1, 5-pentanediol is obtained by separation and purification, wherein the structural formula of the 3, 3-diamyl-1, 5-pentanediol is as follows:

(b) performing esterification reaction; preparing terephthalic acid, ethylene glycol and 3, 3-diamyl-1, 5-pentanediol with the molar ratio of 1:2.0:0.03 into slurry, adding antimony acetate and trimethyl phosphite, uniformly mixing, and pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.2MPa, the esterification reaction temperature is 250 ℃, and the esterification reaction end point is determined when the distilled amount of water in the esterification reaction reaches 97% of a theoretical value, wherein the adding amount of the antimony acetate is 0.01% of the weight of the terephthalic acid, and the adding amount of the trimethyl phosphite is 0.05% of the weight of the terephthalic acid;

(c) performing polycondensation reaction; after the esterification reaction is finished, the polycondensation reaction in the low vacuum stage is started under the condition of negative pressure, the pressure is stably pumped from normal pressure to the absolute pressure of 500Pa within 45min, the reaction temperature is 260 ℃, the reaction time is 40min, then continuously vacuumizing, carrying out polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to 92Pa absolute, the reaction temperature to 277 ℃, reacting for 80min, preparing modified polyester, wherein the molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment and a 3, 3-diamyl-1, 5-pentanediol chain segment, the content of cyclic oligomer in the modified polyester is 0.35 wt%, the number average molecular weight is 25500, the molecular weight distribution index is 1.8, and the molar content of the 3, 3-diamyl-1, 5-pentanediol chain segment in the modified polyester is 5 percent of the molar content of the terephthalic acid chain segment;

(2) and (3) performing solid-phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn. Wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.2 dL/g; the replacement period of the spinning assembly is 47 days, the period for cleaning the spinneret is prolonged by 40 percent, the dipping solution of the first bath in the two-bath dipping method is D-417, and the dipping solution of the second bath is RFL. During the cooling, keep vertical height unchangeable, increase the cross-sectional area of slow cooling cavity, the slow cooling cavity adopts the heat retaining mode to keep the face temperature of spinneret simultaneously, and slow cooling cavity structure is the same basically with embodiment 2, and the difference lies in that it only has the heated board, does not superpose the heat insulating board under the heated board.

TABLE 1

TABLE 2

Note: in Table 2, A represents the center value (%) of the elongation at a load of 4.0cN/dtex, B represents the deviation (%) of the elongation at a load of 4.0cN/dtex, and C represents the dry heat shrinkage (%) at 177 ℃, 10min and 0.05 cN/dtex.

Claims

1. A high-strength polyester industrial yarn is characterized in that: the high-strength polyester industrial yarn is made of modified polyester, a molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment and a dihydric alcohol chain segment with a branched chain, and the structural formula of the dihydric alcohol with the branched chain is as follows:

in the formula, R₁And R₂Each independently selected from linear alkylene having 1 to 3 carbon atoms, R₃Selected from alkyl with 1-5 carbon atoms, R₄Selected from alkyl with 2-5 carbon atoms;

the breaking strength of the high-strength polyester industrial yarn is more than or equal to 8.1 cN/dtex;

the content of cyclic oligomer in the modified polyester is less than or equal to 0.6 wt%;

the modified polyester has a number average molecular weight of 20000 to 27000 and a molecular weight distribution index of 1.8 to 2.2;

the molar content of the dihydric alcohol chain segment with the branched chain in the modified polyester is 3-5% of that of the terephthalic acid chain segment.

2. A high-strength industrial polyester yarn as claimed in claim 1, wherein the fineness of the high-strength industrial polyester yarn is 275 to 1100dtex, the deviation of linear density is ± 1.5%, the CV value of breaking strength is 3.0% or less, the center value of elongation at break is 13.5 to 17.0%, the deviation of elongation at break is ± 1.5%, the CV value of elongation at break is 8.0% or less, the center value of elongation at 4.0cN/dtex load is 5.7 to 6.5%, the deviation of elongation at 4.0cN/dtex load is 0.8%, the dry heat shrinkage under 177 ℃, 10min and 0.05cN/dtex conditions is 4.3 to 9.3%, the network is 6 ± 2/m, and the oil content is 0.4 to 0.9%.

3. The high-strength polyester industrial yarn as claimed in claim 1 or 2, wherein the branched diol is 2-ethyl-2-methyl-1, 3-propanediol, 2-diethyl-1, 3-propanediol, 2-butyl-2-ethyl-1, 3-propanediol, 3-diethyl-1, 5-pentanediol, 4-diethyl-1, 7-heptanediol, 4-bis (1, -methylethyl) -1, 7-heptanediol, 3-dipropyl-1, 5-pentanediol, 4-dipropyl-1, 7-heptanediol, 4-methyl-4- (1, 1-dimethylethyl) -1, 7-heptanediol, 3-methyl-3-pentyl-1, 6-hexanediol or 3, 3-diamyl-1, 5-pentanediol.

4. The high-strength polyester industrial yarn as claimed in claim 3, wherein the preparation method of the modified polyester comprises the following steps: uniformly mixing terephthalic acid, ethylene glycol and the dihydric alcohol with the branched chain, and then sequentially carrying out esterification reaction and polycondensation reaction to obtain modified polyester; the modified polyester comprises the following specific preparation steps:

(1) performing esterification reaction;

(2) performing polycondensation reaction;

5. A high-strength polyester industrial yarn as claimed in claim 4, wherein in the step (1), the molar ratio of the terephthalic acid, the ethylene glycol and the branched diol is 1: 1.2-2.0: 0.03-0.06, the addition amount of the catalyst is 0.01-0.05% of the weight of the terephthalic acid, and the addition amount of the stabilizer is 0.01-0.05% of the weight of the terephthalic acid;

6. A method for preparing the high-strength polyester industrial yarn as claimed in any one of claims 1 to 5, which is characterized in that: performing solid phase polycondensation tackifying, melting, metering, extruding, cooling, oiling, stretching, heat setting and winding on the modified polyester to obtain the high-strength polyester industrial yarn;

during cooling, the longitudinal height is kept unchanged, the cross-sectional area of the slow cooling chamber is increased, and meanwhile, the slow cooling chamber keeps the plate surface temperature of the spinneret plate in a heat preservation mode.

7. The method according to claim 6, wherein the intrinsic viscosity of the modified polyester after solid-phase polycondensation and tackifying is 1.0 to 1.2 dL/g; the spinneret cleaning period is prolonged by 35-45%, and the replacement period of the spinning assembly is more than or equal to 40 days.

8. The method of claim 7, wherein the increasing of the cross-sectional area of the slow cooling chamber means changing the cross-sectional area of the slow cooling chamber from a circular shape to a rectangular shape while maintaining the same spinneret plate connected to the slow cooling chamber; the slow cooling chamber is formed by enclosing a heat insulation plate and spacers, the heat insulation plate is embedded and hung at the bottom of the spinning box body, a hollow chamber I is formed in the heat insulation plate, the spacers are inserted into the hollow chamber I to divide the heat insulation plate into a plurality of slow cooling chambers, and a spinneret plate is arranged in each slow cooling chamber;

the heat insulation plate is a stainless steel plate filled with heat insulation materials capable of resisting temperature of more than 400 ℃, the thickness of the heat insulation plate is 30-50 mm, and the wall thickness of the stainless steel plate is 0.9-1.5 mm;

the heat insulation material is rock wool or ceramic fiber;

the thickness of the spacer is 1-3 mm;

9. The method according to claim 8, characterized in that a heat insulation plate is superposed below the heat insulation plate, the material of the heat insulation plate is the same as that of the heat insulation plate, a hollow chamber II is formed in the heat insulation plate, and the cross sections of the hollow chamber II and the hollow chamber I are the same in shape;

at the position where the hollow chamber II is communicated with the hollow chamber I, two edges of the cross section of the hollow chamber II are respectively superposed with two short edges of the cross section of the hollow chamber I, and the lengths of the two edges are greater than the two short edges;

the thickness of the heat insulation plate is 25-45 mm.

10. The method according to claim 8, wherein the spinning process parameters of the high-strength polyester industrial yarn are as follows:

the technological parameters of stretching and heat setting are as follows: