CN109735979B

CN109735979B - Preparation method of different-fineness and different-dye-uptake polyester low stretch yarn

Info

Publication number: CN109735979B
Application number: CN201811613940.2A
Authority: CN
Inventors: 马文平; 周文龙; 杨超明
Original assignee: Jiangsu Hengli Chemical Fiber Co Ltd
Current assignee: Jiangsu Hengli Chemical Fiber Co Ltd
Priority date: 2018-12-27
Filing date: 2018-12-27
Publication date: 2020-11-06
Anticipated expiration: 2038-12-27
Also published as: CN109735979A

Abstract

The invention relates to a preparation method of different-fineness different-dye-uptake polyester low stretch yarns, which comprises the steps of uniformly mixing terephthalic acid, ethylene glycol and hexanediol with a tert-butyl side group, carrying out esterification reaction and polycondensation reaction to obtain modified polyester, doubling two modified polyester POY yarns with different single-filament fineness, processing according to a DTY process, arranging a groove breaking roller and a variable-frequency yarn shifter between a zero roller and a first roller of a DTY device, passing modified polyester yarn bundles through the surface of the groove breaking roller to obtain the different-fineness different-dye-uptake polyester low stretch yarns, wherein the groove breaking roller is a roller with a plurality of annular grooves engraved on the circumferential surface, the variable-frequency yarn shifter is used for driving the polyester POY yarns to reciprocate on the circumferential surface of the groove breaking roller along the central axis of the roller, and the moving period of the variable-frequency yarn shifter is 5-99 reciprocating times/min. The preparation method provided by the invention is reasonable in operation, and the prepared terylene low stretch yarn with different titer and dye uptake has good dyeing performance.

Description

Preparation method of different-fineness and different-dye-uptake polyester low stretch yarn

Technical Field

The invention belongs to the technical field of polyester fibers, and relates to a preparation method of a polyester low stretch yarn with different titer and different dye uptake.

Background

Terylene is the trade name of polyester fiber in China and is an important variety in synthetic fiber. With the increasing living standard of human beings, the requirements on the quantity and quality of fiber materials in the aspects of clothes, decoration, industry and the like are increasing. In order to meet the demand of people in clothing, decoration, industry and special fields, the development of differentiated fibers with new properties or added values is required. The softness of textile materials is mostly expressed as comfortable touch, smooth surface and lower bending resistance, and the stiffness is mostly expressed as good touch elasticity and recovery performance, higher bending resistance and the like, and the stiffness is the basic style of fibers and is also a physiological and psychological feeling factor of people. The titer of the fiber influences the performance of the yarn and the fabric, the DTY equipment is used for compounding the fibers with different titers, and simultaneously, the fibers generate the effect of different colors, and the effect can be used for simultaneously solving the problems of softness and stiffness of a pair of spear bodies and organically combining the two components together.

In recent years, through research on the performance of natural fibers, synthetic fibers with different titer and similar touch feeling and luster feeling of natural silk fibers are developed, and the application fields and the performances of the synthetic fibers are improved and developed. The bamboo joint yarn with a thick and thin structure can be produced by process optimization control, the air permeability of the fabric is improved, the corresponding crystallinity of the thick and thin structure is different, the dye-uptake difference is large, attractive dark and light stripes can be dyed when the same dye is used for dyeing, and the finished fabric can be used as a high-grade simulation leather suit-dress fabric, umbrella cloth, a filtering material and the like after being subjected to surface coating, calendaring and the like.

However, the prior art for preparing the polyester low stretch yarns with different deniers and different dye uptake rates has single variety, and the fineness and the thickness of each monofilament are limited, so that the prepared fabric has the defects of insufficient softness and incapability of dyeing beautiful dark and light stripes, thereby greatly limiting the development of the polyester low stretch yarns with different deniers and different dye uptake rates. Meanwhile, the terylene molecule does not contain hydrophilic groups, belongs to hydrophobic fibers, and lacks active groups which can be combined with dyes like cellulose or protein fibers in the molecular structure. The finished product of the polyester fiber is a partially crystallized supermolecular structure, molecular chains of the crystallized parts of the polyester fiber are mutually parallel and mostly present a trans conformation, and an amorphous area is mostly present a cis conformation. As known from the molecular structure and crystallization condition of the conventional PET, the molecules are arranged quite tightly, so that the dyeing performance of the conventional PET fiber is poor. Thus, dyeing of conventional PET fibers such as conventional polyester DTY tow is generally done with disperse dyes, usually at high temperature and high pressure. The high-temperature high-pressure dyeing method has high requirements on equipment, long dyeing time and high energy consumption, and can not radically solve the problem of poor dyeing performance of the polyester fiber.

Therefore, how to overcome the problems in the prior art and research the preparation method of the different-titer different-dyeing-rate polyester low stretch yarn which can dye beautiful dark and light stripes when different titers are dyed simultaneously and has good dyeing effect has very important significance.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provides a preparation method of the different-titer different-dye-uptake polyester low stretch yarn, which can dye beautiful dark and light stripes when different titers are dyed simultaneously and has good dyeing effect.

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

the preparation method of the different-denier and different-dye-uptake terylene low stretch yarn comprises the steps of doubling two modified polyester POY yarns with different filament deniers, processing the doubled yarns according to a DTY process, arranging a groove breaking roller and a variable-frequency yarn shifter between a zero roller and a first roller of a DTY device, and passing modified polyester tows through the surface of the groove breaking roller to prepare the different-denier and different-dye-uptake terylene low stretch yarn;

the two modified polyester POY yarns with different filament numbers are prepared from modified polyester melt according to a POY process;

the preparation method of the modified polyester comprises the following steps: uniformly mixing terephthalic acid, ethylene glycol and hexanediol with a tert-butyl side group, and then carrying out esterification reaction and polycondensation reaction in sequence;

the structural formula of hexanediol with tert-butyl side groups is as follows:

in the formula, R is-H, -CH₂CH₃or-C (CH)₃)₃；

According to the different-titer different-dye-uptake polyester low stretch yarn, the hexanediol chain segment with the tert-butyl side group is introduced into the modified polyester molecular chain, the existence of the tert-butyl group in the hexanediol with the tert-butyl side group can cause the change of the main chain mobility, so that the interaction force among chain units is changed, the distance among the chain units is correspondingly changed, the free volume of the cavity of the modified polyester is increased, the increase of the free volume of the cavity is beneficial to the diffusion of dye molecules into the fiber gaps, the dye uptake of the dye is improved, the dyeing temperature is reduced, the dyeing time is shortened, and the dyeing effect is improved;

the groove breaking roller is a roller with a plurality of annular grooves engraved on the peripheral surface, the annular grooves surround the central shaft of the roller and are distributed at equal intervals along the central shaft of the roller, and the variable-frequency filament transfer device is used for driving the polyester POY filaments to reciprocate along the central shaft of the roller on the peripheral surface of the groove breaking roller;

the diameter of the end face of the groove breaking roller is 80 mm; the distance between two adjacent grooves is 6mm, and the distance between the two grooves on the outermost side in the central axis direction of the roller and the end of the roller closest to the grooves is 3.25 mm; the depth of the grooves is 2.6mm, the width is 4mm, and the number of the grooves is 4; the moving period of the variable-frequency wire shifter is 5-99 reciprocating times/min, and the influence of the period is mainly the number of bamboo joints per unit length and is related to the style of a product;

the invention prepares the polyester low stretch yarn with different titer and different dye uptake by additionally arranging the groove breaking roller and the variable frequency yarn shifter in the DTY equipment, wherein the surface of the groove breaking roller is provided with a plurality of annular grooves, because the perimeter of the groove breaking roller in the annular groove is smaller than the perimeter of the groove breaking roller outside the annular groove, the tension applied to the fiber outside the annular groove is larger than that in the annular groove, the stretching multiple of the fiber outside the annular groove is larger (the stretching multiple is controlled to be 1.6-1.8), the stretching multiple of the fiber in the annular groove is smaller (the stretching multiple is controlled to be 1.2-1.3), the variable frequency yarn shifter can drive the polyester POY yarn to reciprocate on the peripheral surface of the groove breaking roller along the central axis of the roller, so that the stretching multiple of the polyester POY yarn is changed instantly, the effect of controlling the change of the thickness and fineness of the polyester DTY yarn is achieved, the polyester DTY yarn is changed by different color absorbing sections, and the finally prepared polyester low stretch yarn with different titer and obvious titer and different dye uptake, one of the characteristics of the different denier and different dye uptake terylene low stretch yarn is that the yarn bundle has certain difference in thickness, a density structure appears in the fabric, and the fabric made of the different denier and different dye uptake terylene low stretch yarn has excellent air permeability (the moisture permeability of the knitted fabric is 150 plus 170 g/m)²H) and because of the large differences in crystallinity between the coarse and fine parts,the dyeing rate of the polyester drawn textured yarn has larger difference, and the fabric made of the polyester drawn textured yarn with different titer and different dyeing rate can be dyed with beautiful dark and light stripes;

the temperature of a second hot box of the DTY process is 130-150 ℃, the general high stretch yarn which is not heated by the second hot box is high stretch yarn, the general low stretch yarn which is heated by the second hot box is low stretch yarn, and the low stretch yarn is prepared by the method.

As a preferred technical scheme:

in the method for preparing the differential-fineness and differential-dyeing-rate polyester low stretch yarn, the single-fineness ratios of the modified polyester POY yarn with larger single-fineness and the modified polyester POY yarn with smaller single-fineness in the differential-fineness and differential-dyeing-rate polyester low stretch yarn are respectively 0.5-0.7 dtex and 1.5-2.5 dtex.

According to the preparation method of the different-titer and different-dyeing-rate polyester drawn textured yarn, the breaking strength of the different-titer and different-dyeing-rate polyester drawn textured yarn is more than or equal to 2.8cN/dtex, the elongation at break is 33.0 +/-3.0%, the linear density deviation rate is less than or equal to 1.5%, the breaking strength CV value is less than or equal to 5.0%, the elongation at break CV value is less than or equal to 10.0%, the boiling water shrinkage rate is 5.9 +/-0.8%, the oil content is 2.50 +/-0.50 wt%, and the crimp shrinkage rate is 14.0 +/-0.5%; compared with the prior art, the quality and quality of the fiber containing the hexanediol chain segment with the tertiary butyl side group are not reduced, and the modified fiber still has good mechanical property, spinnability and the like;

the dyeing rate of the polyester low stretch yarn with different titer and different dyeing rate at the temperature of 120 ℃ is 87.3-91.4%, the soaping-resistant color fastness (polyester staining and cotton staining) reaches 5 grades, the dry friction fastness reaches 5 grades, and the wet friction fastness is higher than 4 grades; under the same other test conditions, the dye uptake of the comparison sample under the temperature condition of 130 ℃ is 85.7%, the soaping color fastness is less than 5 grade, the polyester staining is 4-5 grade, the cotton staining is 4 grade, the dry rubbing fastness is 4-5 grade, the wet rubbing fastness is 3-4 grade, and the difference between the comparison sample and the terylene low stretch yarn with different titer and different dye uptake is only that the material is common polyester;

the polyester low stretch yarn with the different titer and different dye uptake is in a bamboo joint shape, the length of a bamboo joint is 0.31-5.80 pieces/m, the thickness of the bamboo joint-shaped polyester yarn is obviously changed, the bamboo joint-shaped polyester yarn has a bamboo joint yarn-imitating style, a fabric has a special hollow diamond pattern, the hand feeling is fine and comfortable, and the drapability is good.

According to the preparation method of the polyester low stretch yarn with different deniers and different dye uptake rates, the cross sections of the two modified polyester POY yarns with different monofilament deniers are circular.

The method for preparing the polyester drawn textured yarn with different titer and different dye uptake comprises the following steps: firstly, mixing a raw material solution A with the concentration of 300-350 g/L and a dilute sulfuric acid solution with the concentration of 200-300 g/L according to the molar ratio of the raw material A to sulfuric acid of 1.5-2: 1, adding the mixture into a cathode electrolytic cell, then cooling the mixed solution to 10-15 ℃, carrying out electrolytic reduction until the concentration of the raw material A is lower than 10 wt%, and finally carrying out cooling crystallization, separation and purification;

r is-H, -CH₂CH₃and-C (CH)₃)₃In this case, the raw material A is 2, 2-methylpropionaldehyde, 2-dimethyl-3-pentanone, and 2,24, 4-tetramethyl-3-pentanone, respectively.

The preparation method of the modified polyester low stretch yarn with different titer and different dye uptake comprises the following steps:

(1) performing esterification reaction;

preparing terephthalic acid, ethylene glycol and hexanediol with a tert-butyl side group 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 end point is determined when the distilled amount of water in the esterification reaction reaches more than 90% of a theoretical value;

(2) performing polycondensation reaction;

after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, wherein the pressure in the stage is stably pumped from normal pressure to below 500Pa in 30-50 min, the reaction temperature is 250-260 ℃, the reaction time is 30-50 min, then continuously pumping vacuum to perform the polycondensation reaction in a high vacuum stage, so that the reaction pressure is further reduced to below 100Pa, the reaction temperature is 270-282 ℃, and the reaction time is 50-90 min.

According to the preparation method of the different-titer different-dye-uptake polyester drawn textured yarn, the molar ratio of the terephthalic acid to the ethylene glycol to the hexanediol with the tert-butyl side group is 1: 1.2-2.0: 0.03-0.05, and the addition amounts of the catalyst and the stabilizer are 0.03-0.05 wt% and 0.01-0.05 wt% (mass percentage) of the addition amount of the terephthalic acid respectively; the preferable range of the addition amount of the hexanediol with the tertiary butyl side group can ensure that the modified fiber has good mechanical property and crystallinity, and can also obviously improve the dyeing property of the fiber, thereby being beneficial to the production and application of the fiber.

According to the preparation method of the polyester low stretch yarn with different titer and different dye uptake, the catalyst is antimony trioxide, ethylene glycol antimony or antimony acetate, and the stabilizer is triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.

According to the preparation method of the polyester drawn textured yarn with different titer and different dye uptake, the number average molecular weight of the modified polyester is 25000-30000, and the molecular weight distribution index is 1.8-2.2.

The preparation method of the polyester drawn textured yarn with different titer and different dye uptake comprises the following steps: metering, spinneret plate extrusion, cooling, oiling and winding;

the parameters of the POY process are as follows: the spinning temperature is 280-285 ℃, the cooling temperature is 17-20 ℃, and the winding speed is 3200-3600 m/min;

the DTY process comprises the following steps: guide wire, plying, network, heating and stretching, false twisting, heat setting and winding;

the DTY process has the following parameters: the spinning speed is 500-700 m/min, the setting overfeed rate is 3.5-5.5%, the winding overfeed rate is 3.0-5.5%, the temperature of a first hot box is 180-200 ℃, and the drawing ratio is 1.2-1.7.

The invention mechanism is as follows:

the mechanism that the polyester low stretch yarn with different titer and different dye uptake prepared by the invention can dye beautiful dark and light stripes is as follows:

the large molecular chain and the aggregation structural unit of the fiber are stretched in the drafting process of the pre-oriented POY, the orientation degree is improved, high energy can be given to the fiber during drafting, the molecular conformation is continuously changed to a stable state with low energy barrier, the curled macromolecules are gradually straightened, the crystal lattice is easy to lay in, the acting force among the macromolecules is strengthened, the crystal area structure is complete, and finally the crystallinity is increased. In the process of fiber hot drawing, molecular chains compete with each other in orientation, relaxation orientation and crystallization, and products with different orientations and crystal structures can be obtained by reasonably combining drawing temperature and drawing multiple, so that the performances of the products are different.

The invention causes the difference of the stretching multiples of the fiber by additionally arranging the groove breaking roller and the variable-frequency filament transferor in the DTY equipment, the surface of the groove breaking roller is provided with a plurality of annular grooves, the circumference of the groove breaking roller in the annular groove is smaller than that of the groove breaking roller outside the annular groove, so that the fiber is subjected to a larger tension outside the annular groove than in the annular groove, the stretching multiple of the fiber outside the annular groove is larger (the stretching multiple is controlled to be 1.6-1.8), the stretching multiple of the fiber in the annular groove is smaller (the stretching multiple is controlled to be 1.2-1.3), the variable-frequency filament transferor can drive the polyester POY filament to reciprocate along the central shaft of the roller on the circumferential surface of the groove breaking roller, the stretching multiple of the polyester POY filament is changed instantly, the effect of controlling the change of the thickness and fineness of the polyester DTY filament is obtained, and the change of different color absorbing segments of the polyester DTY filament is caused.

The difference of the stretching ratio of the fiber can lead the thickness of the fiber to be regularly changed. With the increase of the drafting multiple, the fineness of the fiber is continuously reduced, the orientation degree of a macromolecular axis is increased, the strength of the fiber is increased, the elongation is reduced, the initial modulus is improved, the crystallinity is increased, the dyed fiber has color which is presented by the fact that the dye contained in the fiber selectively absorbs visible light and reflects the visible light or transmits complementary color of absorbed light, the depth of the color is related to the strength of the fiber in reflection and scattering of the light, the smaller the fineness of the fiber is, the thinner the fiber is, the larger the specific surface area of the fiber is, the stronger the reflection of the surface of the fiber is, the less the light enters the fiber, and the weaker the light reflected or transmitted by the fiber after being absorbed is, the lighter the color of the fiber is; therefore, the fine portion has a large degree of crystallinity and orientation, and the apparent color depth after dyeing is low; the coarse part has small crystallinity and orientation degree, and the dyed apparent color has high depth, so that the fibers have the phenomena of different titer and different dyeing rate, and the fabric made of the terylene low stretch yarn with different titer and different dyeing rate can be dyed into beautiful dark and light stripes.

The invention solves the problem of poor dyeing effect of the polyester low stretch yarn with different titer and different dye uptake prepared by the prior art by the following mechanism:

the macromolecular chains in the polymer are not completely tightly packed, and voids always exist among the macromolecular chains, and the void volume is the free volume. Since small molecules are allowed to penetrate into the polymer, voids are sufficiently large in the polymer or between the polymers, the permeability and diffusivity of the small molecules are related to the size of the voids (i.e., the size of free volume) in the polymer structure, and within a certain range, the larger the size of the free volume, the higher the permeability of the small molecules, and the better the diffusivity. The free volume is divided into a cavity free volume and a slit free volume, the cavity free volume has larger space size than the slit free volume, and the effect of the cavity free volume is more obvious than the effect of the slit free volume for improving the permeability of small molecules.

The size and type of free volume depends primarily on the structure of the polymer, and the primary factors affecting the polymer structure are steric hindrance, pendant group size, pendant group structure, and the like. When a certain position on the main chain of the polymer is substituted by a side group, the activity of the main chain is inevitably changed, so that the interaction force between chains is changed, the distance between the chains is also correspondingly changed, and consequently, the cohesive energy and the free volume are changed, and the polarity, the size, the length and the like of the substituent on the side chain of the polymer have certain influences on the rigidity of the molecular chain, the interaction between molecules and the free volume fraction of the polymer structure, so that the effects generated by different substituents are different, and the osmotic separation performance of the polymer is often different.

For glycol straight chain molecules such as ethylene glycol and butanediol, the C atoms on the main chain are arranged in a zigzag manner from top to bottom, and when the H atom on a certain methylene on the main chain is replaced by a methyl group (-CH)₃) When in substitution, the C atoms on the side groups and the main chain C atoms are not in the same plane, so that four sp3 hybridized orbitals on the center C are respectively overlapped with empty orbitals on the four surrounding C atoms to form four completely same sigma bonds which are arranged in a regular tetrahedron, the four carbon atoms are respectively positioned at four vertexes of the regular tetrahedron, when three hydrogen of a methyl group is further substituted by a methyl group, the three hydrogen is equivalent to tert-butyl to form a larger tetrahedron structure, the molecular chain arranged in the regular tetrahedron is relatively arranged in a zigzag shape, the free volume of the cavity is obviously increased by a lot, and the permeability and the diffusivity of small molecules can be obviously improved; when the H atom on a certain methylene on the main chain is replaced by the long branched chain substituent, the slit free volume is mainly increased, the increase amplitude is small, the improvement effect on the permeability and the diffusivity of the micromolecule is limited, and meanwhile, the long branched chain substituent has low rigidity, the molecular chains are easy to tangle, and the increase of the free volume is not facilitated.

The invention obviously improves the dyeing property of the polyester industrial yarn by introducing the hexanediol with the tertiary butyl side group into a polyester molecular chain, and the structural formula of the hexanediol with the tertiary butyl side group is as follows:

wherein R is-H (hexanediol with tert-butyl side group is 2,2,5, 5-tetramethyl-3, 4-hexanediol), -CH₂CH₃(hexanediol with pendant tert-butyl groups is 2,2,5, 5-tetramethyl-3, 4-diethyl-3, 4-hexanediol) or-C (CH)₃)₃(hexanediol with pendant tert-butyl groups is 2,2,4, 4-tetramethyl-3, 4-di-tert-butyl-3, 4-hexanediol);

the existence of the tertiary butyl group in hexanediol with the tertiary butyl group side group can cause the change of the activity of a main chain, thereby changing the interaction force among chain units, and correspondingly changing the distance among the chain units, so that the free volume of a cavity of the modified polyester is increased. Compared with short-chain substituent groups (such as methyl, ethyl and the like), the tertiary butyl group occupies a larger spatial position, and a larger free volume is obtained in the molecular chain arrangement mode; compared with the long-branched-chain substituent, on one hand, the tertiary butyl group has a hollow space and the long-branched-chain substituent has a slit free volume, and on the other hand, the rigidity of the tertiary butyl group is higher than that of the long-branched-chain substituent, so that entanglement among molecular chains is reduced, and the tertiary butyl group has more free volume than the long-branched-chain substituent in the arrangement mode of the molecular chains. The introduction of hexanediol with a tert-butyl side group increases the free volume of the cavity of the modified polyester, which helps to diffuse part of dye molecules into fiber gaps in the dyeing process, thus reducing the dyeing temperature, shortening the dyeing time, reducing the energy consumption and simultaneously improving the dye uptake of the fiber.

Has the advantages that:

(1) according to the preparation method of the different-titer and different-dye-uptake polyester low stretch yarn, the hexanediol with the tert-butyl side group and the specific structure is introduced into the polyester molecular chain, so that the cavity free volume of the polyester is increased, dye small molecules can easily permeate into the polyester, the dyeing performance of the polyester low stretch yarn is improved, the dye-uptake and the color fastness of the polyester low stretch yarn are improved, and the dyeing quality of a fabric can be improved;

(2) the preparation method of the polyester low stretch yarn with the different titer and the different dye uptake is simple to operate, only needs to modify polyester, adds the groove breaking roller and the variable frequency yarn shifter in DTY equipment, and controls the yarn bundle to pass through the surface of the groove breaking roller along a specific direction at a specific frequency;

(3) the preparation method of the polyester low stretch yarn with different titer and different dye uptake can prepare the polyester low stretch yarn with clear nubs and details, excellent air permeability and excellent dyeing effect, and can dye beautiful dark and light stripes when the polyester low stretch yarn is dyed by the same dye bath.

Drawings

FIG. 1 is a schematic diagram of a reaction apparatus for synthesizing hexanediol with a t-butyl side group according to the present invention;

FIG. 2 is a schematic diagram of the structure of the DTY apparatus of the present invention;

FIG. 3 is a front view of the trenching roller of the present invention;

FIG. 4 is a left side view of the trenching roller of the present invention;

fig. 5 is a schematic structural diagram of a DTY device in the prior art.

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

The preparation method of the polyester low stretch yarn with different titer and different dye uptake comprises the following steps:

(1) preparing modified polyester;

(1.1) synthesizing 2,2,5, 5-tetramethyl-3, 4-hexanediol by the following steps: firstly, mixing a 2, 2-methylpropionaldehyde solution with the concentration of 320g/L and a dilute sulfuric acid solution with the concentration of 200g/L according to the molar ratio of 2, 2-methylpropionaldehyde to sulfuric acid of 1.5:1, adding the mixture into a cathode electrolytic cell, then cooling the mixed solution to 12 ℃, then carrying out electrolytic reduction to the concentration of 2, 2-methylpropionaldehyde of 9.5 wt%, and finally carrying out cooling crystallization, separation and purification, wherein the schematic diagram of a reaction device adopted in the synthetic process is shown in figure 1, and the reaction chemical equation is as follows:

the structural formula of the prepared 2,2,5, 5-tetramethyl-3, 4-hexanediol is shown as a formula (I), wherein R is-H;

(1.2) esterification reaction;

preparing terephthalic acid, ethylene glycol and 2,2,5, 5-tetramethyl-3, 4-hexanediol 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 0.1MPa, the esterification reaction temperature is 250 ℃, the esterification reaction end point is the end point when the distilled water amount in the esterification reaction reaches 93% of a theoretical value, and the adding amounts of the antimony trioxide and the triphenyl phosphate are respectively 0.03 wt% and 0.02 wt% of the adding amount of the terephthalic acid;

(1.3) a polycondensation reaction;

after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, stably pumping the pressure in the stage from normal pressure to absolute pressure of 480Pa within 30min, controlling the reaction temperature to be 250 ℃ and the reaction time to be 31min, then continuing to pump vacuum, and carrying out the polycondensation reaction in a high vacuum stage to further reduce the reaction pressure to absolute pressure of 100Pa, control the reaction temperature to be 270 ℃ and control the reaction time to be 50min, wherein the number average molecular weight of the prepared modified polyester is 30000 and the molecular weight distribution index is 2.0;

(2) preparing two modified polyester POY yarns with different filament numbers;

respectively carrying out metering, spinneret plate extrusion, cooling, oiling and winding on the modified polyester melt to obtain modified polyester POY (polyester pre-oriented yarn) with round cross sections and 0.5dtex and 1.5dtex of filament number respectively, wherein the parameters of the POY process are as follows: the spinning temperature is 285 ℃, the cooling temperature is 17 ℃, and the winding speed is 3500 m/min;

(3) preparing the polyester low stretch yarn with different titer and different dye uptake;

the modified polyester POY yarns with different filament deniers are doubled and then processed according to a DTY process, and the DTY equipment for the polyester DTY process comprises a raw yarn frame, a yarn cutter, a zero roller, a variable frequency yarn shifter, a groove breaking roller, a first roller, a slide rail, a first hot box, a cooling plate, a false twister, a tension meter, a second roller, a network nozzle, a second hot box, a third roller, an oil wheel and a winder, wherein the front view and the left view of the groove breaking roller are respectively shown in the figures 3 and 4, the groove breaking roller is a roller with a plurality of annular grooves engraved on the peripheral surface, the annular grooves surround the central shaft of the roller and are distributed at equal intervals along the central shaft of the roller, the variable frequency yarn shifter is used for driving the modified polyester POY yarns to reciprocate on the peripheral surface of the groove breaking roller along the central shaft of the roller, and the diameter of the end surface of the groove breaking roller is 80 mm; the distance between two adjacent grooves is 6mm, and the distance between the two grooves on the outermost side in the central axis direction of the roller and the end of the roller closest to the grooves is 3.25 mm; the depth of the grooves is 2.6mm, the width is 4mm, and the number of the grooves is 4;

the modified polyester POY yarn on the raw yarn frame is guided out by a yarn guide pipe and then sequentially passes through a yarn cutter, a zero roller, a variable frequency yarn shifter, the surface of a groove breaking roller, a first hot box, a cooling plate, a false twister, a tension meter, a second roller, a network nozzle, a second hot box, a third roller, an oil wheel and a winder to complete the processes of yarn guide, stranding, network, heating and stretching, false twisting, heat setting and winding, namely the DTY process is completed to obtain the different-titer different-dyeing-rate polyester low-stretch yarn, wherein the moving period of the variable frequency yarn shifter is 99 reciprocating times/min, and the parameters of the DTY process are as follows: the spinning speed is 400m/min, the setting overfeed rate is 3.5 percent, the winding overfeed rate is 4.0 percent, the temperature of the first hot box is 190 ℃, the temperature of the second hot box is 130 ℃, and the drawing ratio is 1.7.

The titer ratio of the modified polyester POY yarn with larger monofilament titer to the modified polyester POY yarn with smaller monofilament titer in the finally prepared polyester low stretch yarn with different titer and different dye uptake is 1: 1; the breaking strength of the different-fineness and different-dye-uptake polyester low stretch yarn is 2.92cN/dtex, the elongation at break is 30.0 percent, the linear density deviation rate is 1.44 percent, the breaking strength CV value is 5.0 percent, the elongation at break CV value is 9.8 percent, the boiling water shrinkage rate is 5.9 percent, the oil content is 2.2 percent by weight, and the crimp shrinkage rate is 19.0 percent;

the dyeing rate of the polyester drawn textured yarn with different titer and different dyeing rate at the temperature of 120 ℃ is 87.3 percent, the soaping color fastness reaches 5 grade, the dry friction fastness reaches 5 grade, and the wet friction fastness reaches 5 grade;

the polyester low stretch yarn with different titer and different dye uptake is in a bamboo joint shape, and the length of the bamboo joint is 5.80 pieces/m.

Comparative example 1

The preparation method of the different-titer and different-dye-uptake polyester low stretch yarn has the steps basically consistent with those of example 1, and is different in that polyester is not modified, and the titer ratio of the modified polyester POY yarn with larger monofilament titer to the modified polyester POY yarn with smaller monofilament titer in the prepared different-titer and different-dye-uptake polyester low stretch yarn is 1: 1; the breaking strength of the different-fineness and different-dye-uptake polyester low stretch yarn is 2.92cN/dtex, the elongation at break is 30.0%, the linear density deviation rate is 1.44%, the breaking strength CV value is 5.0%, the elongation at break CV value is 9.8%, the boiling water shrinkage rate is 5.9%, the oil content is 2.2 wt%, the crimp shrinkage rate is 19.0%, and the slub length is 5.80 pieces/m; under the same conditions as other testing conditions of example 1, the dye uptake of the comparative sample at the temperature of 130 ℃ is 85.7%, the soaping-resistant color fastness is 4-5 grades, the dry rubbing fastness is 4-5 grades, the wet rubbing fastness is 3-4 grades, and the comparative sample is different from the differential titer and differential dye uptake polyester low stretch yarn of the invention only in that the material is common polyester. The two comparisons show that the dyeing property of the polyester fiber is greatly improved by modifying the polyester, and the mechanical property is not influenced.

Comparative example 2

The preparation method of the different-titer and different-dye-uptake polyester low stretch yarn is basically the same as that in the embodiment 1, and is characterized in that 1, 2-dodecyl glycol is adopted to replace 2,2,5, 5-tetramethyl-3, 4-hexanediol in the step (1), and the titer ratio of the modified polyester POY yarn with larger monofilament titer to the modified polyester POY yarn with smaller monofilament titer in the prepared different-titer and different-dye-uptake polyester low stretch yarn is 1: 1; the breaking strength of the different-fineness and different-dye-uptake polyester low stretch yarn is 2.85cN/dtex, the elongation at break is 32.0%, the linear density deviation rate is 1.48%, the breaking strength CV value is 5.1%, the elongation at break CV value is 9.8%, the boiling water shrinkage rate is 6.5%, the oil content is 2.2 wt%, the crimp shrinkage rate is 19.0%, and the slub length is 5.80 pieces/m. Under the same conditions as other testing conditions of example 1, the dye uptake of the produced polyester drawn textured yarn with different titer and different dye uptake at the temperature of 130 ℃ is 85.2%, the soaping resistance color fastness is 4-5 grade, the dry rubbing fastness is 4 grade, the wet rubbing fastness is 4 grade, and the dye uptake is lower than that of the polyester drawn textured yarn prepared by the invention.

In comparison with example 1, it was found that hexanediol with pendant tertiary butyl groups (2,2,5, 5-tetramethyl-3, 4-hexanediol) is more advantageous in improving the dyeability of the fibers than 1, 2-dodecyldiol with long chain substituents, mainly because hexanediol with pendant tertiary butyl groups on one side increases the free volume more to be the void free volume and long chain substituents increase the free volume more to be the slit free volume, and hexanediol with pendant tertiary butyl groups on the other side has greater rigidity than long chain substituents, reduces entanglement between the molecular chains, and thus hexanediol with pendant tertiary butyl groups has more free volume in the molecular chain arrangement than long chain substituents, and the increase in the free volume of voids will help the diffusion of the dye into the fiber voids, increasing the dye uptake of the fibers, the dyeing temperature is reduced, the dyeing time is shortened, and the dyeing property of the fiber is improved more favorably compared with that of a long branched chain substituent.

Comparative example 3

The preparation method of the polyester yarn is basically the same as that of the embodiment 1, and is different in that DTY equipment adopted when the polyester yarn is prepared is shown in figure 5, and a variable frequency yarn shifter and a groove breaking roller are not contained in the DTY equipment. The finally prepared polyester yarn is the conventional polyester DTY yarn and is not in the bamboo joint shape, and the comparison of the example 1 and the comparative example 3 shows that the invention can prepare the beautiful and good-quality bamboo joint-shaped polyester low stretch yarn just under the action of the variable frequency yarn shifter and the groove breaking roller.

Example 2

(1) preparing modified polyester;

(1.1) synthesizing 2,2,5, 5-tetramethyl-3, 4-diethyl-3, 4-hexanediol by the following steps: firstly, mixing a 2, 2-dimethyl 3-pentanone solution with the concentration of 350g/L and a dilute sulfuric acid solution with the concentration of 210g/L according to the molar ratio of the 2, 2-dimethyl 3-pentanone to the sulfuric acid of 1.6:1, adding the mixture into a cathode electrolytic cell, then cooling the mixed solution to 11 ℃, then carrying out electrolytic reduction to the concentration of 9.0 wt% of the 2, 2-dimethyl 3-pentanone, finally carrying out cooling crystallization, separation and purification, wherein a reaction device and a reaction chemical equation adopted in the synthesis process are consistent with those of example 1, and the prepared 2,2,5, 5-tetramethyl is preparedThe structural formula of the (E) -3, 4-diethyl-3, 4-hexanediol is shown as a formula (I), wherein R is-CH₂CH₃；

(1.2) esterification reaction;

preparing terephthalic acid, ethylene glycol and 2,2,5, 5-tetramethyl-3, 4-diethyl-3, 4-hexanediol with a molar ratio of 1:1.5:0.034 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 normal pressure, the esterification reaction temperature is 251 ℃, the esterification reaction end point is determined when the distilled amount of water in the esterification reaction reaches 92% of a theoretical value, and the adding amounts of the ethylene glycol antimony and the trimethyl phosphate are respectively 0.04 wt% and 0.01 wt% of the adding amount of the terephthalic acid;

(1.3) a polycondensation reaction;

after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, stably pumping the pressure in the stage from normal pressure to the absolute pressure of 500Pa within 30min, controlling the reaction temperature to be 252 ℃ and the reaction time to be 30min, then continuously pumping the vacuum to perform the polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to the absolute pressure of 100Pa, controlling the reaction temperature to be 271 ℃ and the reaction time to be 55min, wherein the number average molecular weight of the prepared modified polyester is 29000 and the molecular weight distribution index is 2.1;

(2) preparing two modified polyester POY yarns with different filament numbers;

respectively carrying out metering, spinneret plate extrusion, cooling, oiling and winding on the modified polyester melt to obtain modified polyester POY (polyester pre-oriented yarn) with round cross sections and 0.5dtex and 2.5dtex of filament number respectively, wherein the parameters of the POY process are as follows: the spinning temperature is 280 ℃, the cooling temperature is 17 ℃, and the winding speed is 3200 m/min;

two modified polyester POY yarns with different filament titer are doubled and then processed according to a DTY process, the modified polyester POY yarns are subjected to the DTY process flow which is basically the same as that of the embodiment 1 by adopting DTY equipment with the same structure as that of the embodiment 1 to prepare the polyester low stretch yarns with different titer and different dye uptake, the DTY process is different from the embodiment 1 in that the moving period of a frequency conversion yarn shifter is 5 reciprocating times/min, and the parameters of the DTY process are as follows: the spinning speed is 500m/min, the setting overfeed rate is 5.5 percent, the winding overfeed rate is 3.0 percent, the temperature of the first hot box is 180 ℃, the temperature of the second hot box is 140 ℃, and the drawing ratio is 1.65.

The titer ratio of the modified polyester POY yarn with larger monofilament titer to the modified polyester POY yarn with smaller monofilament titer in the finally prepared polyester low stretch yarn with different titer and different dye uptake is 1.2: 1; the breaking strength of the different-fineness and different-dye-uptake polyester low stretch yarn is 2.8cN/dtex, the elongation at break is 33.0 percent, the linear density deviation rate is 1.46 percent, the breaking strength CV value is 4.9 percent, the elongation at break CV value is 9.9 percent, the boiling water shrinkage rate is 5.1 percent, the oil content is 3.0 percent by weight, and the crimp shrinkage rate is 9.0 percent;

the dyeing rate of the different-titer and different-dyeing-rate polyester low stretch yarn at the temperature of 120 ℃ is 89.23 percent, the soaping-resistant color fastness reaches 5 grades, the dry friction fastness reaches 5 grades, and the wet friction fastness reaches 5 grades;

the polyester low stretch yarn with different titer and different dye uptake is in a bamboo joint shape, and the length of the bamboo joint is 0.31/m.

Example 3

(1) preparing modified polyester;

(1.1) synthesizing 2,2,4, 4-tetramethyl-3, 4-di-tert-butyl-3, 4-hexanediol by the following steps: firstly, mixing a 2,24, 4-tetramethyl-3-pentanone solution with the concentration of 340g/L and a dilute sulfuric acid solution with the concentration of 230g/L according to the molar ratio of the 2,24, 4-tetramethyl-3-pentanone to the sulfuric acid of 1.7:1, adding the mixture into a cathode electrolytic cell, then cooling the mixed solution to 10 ℃, carrying out electrolytic reduction until the concentration of the 2,24, 4-tetramethyl-3-pentanone is 9.6 wt%, and finally carrying out cooling crystallization, separation and purification, wherein a reaction device and a reaction chemical equation adopted in the synthetic process are consistent with those of example 1, and the structural formula of the prepared 2,2,4, 4-tetramethyl-3, 4-di-tert-butyl-3, 4-hexanediol is shown as a formula (I), wherein R is-C (CH) (CH 3, 4-hexanediol)₃)₃；

(1.2) esterification reaction;

preparing terephthalic acid, ethylene glycol and 2,2,4, 4-tetramethyl-3, 4-di-tert-butyl-3, 4-hexanediol with a molar ratio of 1:1.8:0.037 into slurry, adding antimony acetate and trimethyl phosphite, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurization pressure is normal pressure, the esterification reaction temperature is 252 ℃, the esterification reaction end point is the end point when the distilled amount of water in the esterification reaction reaches 90% of a theoretical value, and the adding amounts of the antimony acetate and the trimethyl phosphite are respectively 0.04 wt% and 0.03 wt% of the adding amount of the terephthalic acid;

(1.3) a polycondensation reaction;

after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, stably pumping the pressure in the low vacuum stage from normal pressure to the absolute pressure of 450Pa within 35min, controlling the reaction temperature to be 253 ℃ and controlling the reaction time to be 35min, then continuously pumping the vacuum to perform the polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to the absolute pressure of 90Pa, controlling the reaction temperature to be 274 ℃ and controlling the reaction time to be 60min, wherein the number average molecular weight of the prepared modified polyester is 37500 and the molecular weight distribution index is 2.2;

(2) preparing two modified polyester POY yarns with different filament numbers;

respectively carrying out metering, spinneret plate extrusion, cooling, oiling and winding on the modified polyester melt to obtain modified polyester POY (polyester pre-oriented yarn) with round cross sections and 0.6dtex and 1.5dtex of filament number respectively, wherein the parameters of the POY process are as follows: the spinning temperature is 285 ℃, the cooling temperature is 20 ℃, and the winding speed is 3600 m/min;

two modified polyester POY yarns with different filament deniers are doubled and then processed according to a DTY process, the modified polyester POY yarns are subjected to the DTY process flow which is basically the same as that of the example 1 by adopting DTY equipment with the same structure as that of the example 1 to prepare the polyester low stretch yarns with different denier and different dye uptake, the DTY process is different from the example 1 in that the moving period of a frequency conversion yarn shifter is 15 reciprocating times/min, and the parameters of the DTY process are as follows: the spinning speed is 500m/min, the setting overfeed rate is 3.5 percent, the winding overfeed rate is 3.0 percent, the temperature of the first hot box is 180 ℃, the temperature of the second hot box is 150 ℃, and the drawing ratio is 1.7.

The titer ratio of the modified polyester POY yarn with larger monofilament titer to the modified polyester POY yarn with smaller monofilament titer in the finally prepared polyester low stretch yarn with different titer and different dye uptake is 1.5: 1.3; the breaking strength of the different-fineness and different-dye-uptake polyester low stretch yarn is 2.95cN/dtex, the elongation at break is 33.0 percent, the linear density deviation rate is 1.5 percent, the breaking strength CV value is 4.7 percent, the elongation at break CV value is 10.0 percent, the boiling water shrinkage rate is 6.7 percent, the oil content is 2.50 percent by weight, and the crimp shrinkage rate is 14.5 percent;

the dyeing rate of the polyester drawn textured yarn with different titer and different dyeing rate at the temperature of 120 ℃ is 88.2 percent, the soaping color fastness reaches 5 grade, the dry friction fastness reaches 5 grade, and the wet friction fastness reaches 6 grade;

the polyester low stretch yarn with different titer and different dye uptake is in a bamboo joint shape, and the length of the bamboo joint is 0.93 per meter.

Example 4

(1) preparing modified polyester;

(1.1) synthesizing 2,2,5, 5-tetramethyl-3, 4-hexanediol by the following steps: firstly, mixing a 2, 2-methylpropionaldehyde solution with the concentration of 300g/L and a dilute sulfuric acid solution with the concentration of 250g/L according to the molar ratio of the 2, 2-methylpropionaldehyde to sulfuric acid of 1.8:1, adding the mixture into a cathode electrolytic cell, then cooling the mixed solution to 15 ℃, carrying out electrolytic reduction to the concentration of the 2, 2-methylpropionaldehyde of 9.3 wt%, and finally carrying out cooling crystallization, separation and purification, wherein a reaction device and a reaction chemical equation adopted in the synthesis process are consistent with those of example 1, and the structural formula of the prepared 2,2,5, 5-tetramethyl-3, 4-hexanediol is shown as a formula (I), wherein R is-H;

(1.2) esterification reaction;

preparing terephthalic acid, ethylene glycol and 2,2,5, 5-tetramethyl-3, 4-hexanediol with a molar ratio of 1:1.9:0.04 into slurry, adding antimony acetate and triphenyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.3MPa, the esterification reaction temperature is 254 ℃, the esterification reaction end point is determined when the water distillation amount in the esterification reaction reaches 96% of a theoretical value, and the adding amounts of the antimony acetate and the triphenyl phosphate are respectively 0.03 wt% and 0.05 wt% of the adding amount of the terephthalic acid;

(1.3) a polycondensation reaction;

after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, wherein the pressure in the stage is stably pumped from normal pressure to the absolute pressure of 410Pa within 40min, the reaction temperature is 255 ℃, the reaction time is 32min, then continuously pumping vacuum, and carrying out the polycondensation reaction in a high vacuum stage, so that the reaction pressure is further reduced to the absolute pressure of 95Pa, the reaction temperature is 275 ℃, the reaction time is 70min, the number average molecular weight of the prepared modified polyester is 25000, and the molecular weight distribution index is 2.2;

(2) preparing two modified polyester POY yarns with different filament numbers;

respectively carrying out metering, spinneret plate extrusion, cooling, oiling and winding on the modified polyester melt to obtain modified polyester POY (polyester pre-oriented yarn) with round cross sections and 0.6dtex and 2.0dtex of filament number respectively, wherein the parameters of the POY process are as follows: the spinning temperature is 282 ℃, the cooling temperature is 20 ℃, and the winding speed is 3500 m/min;

two modified polyester POY yarns with different filament titer are doubled and then processed according to a DTY process, the modified polyester POY yarns are subjected to the DTY process flow which is basically the same as that of the example 1 by adopting DTY equipment with the same structure as that of the example 1 to prepare the polyester low stretch yarns with different titer and different dye uptake, the DTY process is different from the example 1 in that the moving period of a frequency conversion yarn shifter is 25 reciprocating times/min, and the parameters of the DTY process are as follows: the spinning speed is 500m/min, the setting overfeed rate is 4.5 percent, the winding overfeed rate is 5.5 percent, the temperature of the first hot box is 200 ℃, the temperature of the second hot box is 150 ℃, and the drawing ratio is 1.4.

The titer ratio of the modified polyester POY yarn with larger monofilament titer to the modified polyester POY yarn with smaller monofilament titer in the finally prepared polyester low stretch yarn with different titer and different dye uptake is 2: 1; the breaking strength of the different-fineness and different-dye-uptake polyester low stretch yarn is 2.96cN/dtex, the elongation at break is 36.0 percent, the linear density deviation rate is 1.38 percent, the breaking strength CV value is 4.85 percent, the elongation at break CV value is 9.7 percent, the boiling water shrinkage rate is 5.9 percent, the oil content is 2.0 percent by weight, and the crimp shrinkage rate is 13.5 percent;

the dyeing rate of the polyester drawn textured yarn with different titer and different dyeing rate at the temperature of 120 ℃ is 91.4 percent, the soaping color fastness reaches 5 grade, the dry friction fastness reaches 5 grade, and the wet friction fastness reaches 6 grade;

the polyester low stretch yarn with different titer and different dye uptake is in a bamboo joint shape, and the length of the bamboo joint is 1.53 pieces/m.

Example 5

(1) preparing modified polyester;

(1.1) synthesizing 2,2,5, 5-tetramethyl-3, 4-diethyl-3, 4-hexanediol by the following steps: firstly, mixing a 2, 2-dimethyl 3-pentanone solution with the concentration of 310g/L and a dilute sulfuric acid solution with the concentration of 300g/L according to the molar ratio of the 2, 2-dimethyl 3-pentanone to the sulfuric acid of 1.9:1, adding the mixture into a cathode electrolytic cell, then cooling the mixed solution to 15 ℃, then carrying out electrolytic reduction to the concentration of the 2, 2-dimethyl 3-pentanone of 8.8 wt%, and finally carrying out cooling crystallization, separation and purification, wherein a reaction device and a reaction chemical equation adopted in the synthetic process are consistent with those of example 1, and the structural formula of the prepared 2,2,5, 5-tetramethyl-3, 4-diethyl-3, 4-hexanediol is shown as a formula (I), wherein R is-CH (CH-CH) in the formula₂CH₃；

(1.2) esterification reaction;

preparing terephthalic acid, ethylene glycol and 2,2,5, 5-tetramethyl-3, 4-diethyl-3, 4-hexanediol with the molar ratio of 1:2.0:0.042 into slurry, adding ethylene glycol antimony and trimethyl phosphite, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.2MPa, the esterification reaction temperature is 256 ℃, the esterification reaction end point is the end point when the distilled water amount in the esterification reaction reaches 99% of a theoretical value, and the adding amounts of the ethylene glycol antimony and the trimethyl phosphite are respectively 0.03 wt% and 0.04 wt% of the adding amount of the terephthalic acid;

(1.3) a polycondensation reaction;

after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, stably pumping the pressure in the stage from normal pressure to absolute pressure of 490Pa within 45min, controlling the reaction temperature to 257 ℃ and the reaction time to 40min, then continuing to pump vacuum, and carrying out the polycondensation reaction in a high vacuum stage to further reduce the reaction pressure to absolute pressure of 90Pa, control the reaction temperature to 277 ℃ and control the reaction time to 75min, wherein the number average molecular weight of the prepared modified polyester is 27800 and the molecular weight distribution index is 1.8;

(2) preparing two modified polyester POY yarns with different filament numbers;

respectively carrying out metering, spinneret plate extrusion, cooling, oiling and winding on the modified polyester melt to obtain modified polyester POY (polyester pre-oriented yarn) with round cross sections and 0.7dtex and 2.2dtex of filament number respectively, wherein the parameters of the POY process are as follows: the spinning temperature is 280 ℃, the cooling temperature is 17 ℃, and the winding speed is 3200 m/min;

two modified polyester POY yarns with different filament titer are doubled and then processed according to a DTY process, the modified polyester POY yarns are subjected to the DTY process flow which is basically the same as that of the example 1 by adopting DTY equipment with the same structure as that of the example 1 to prepare the polyester low stretch yarns with different titer and different dye uptake, the DTY process is different from the example 1 in that the moving period of a frequency conversion yarn shifter is 50 reciprocating times/min, and the parameters of the DTY process are as follows: the spinning speed is 700m/min, the setting overfeed rate is 4.0 percent, the winding overfeed rate is 4.5 percent, the temperature of the first hot box is 195 ℃, the temperature of the second hot box is 130 ℃, and the drawing ratio is 1.2.

The titer ratio of the modified polyester POY yarn with larger monofilament titer to the modified polyester POY yarn with smaller monofilament titer in the finally prepared polyester low stretch yarn with different titer and different dye uptake is 2: 1.4; the breaking strength of the different-fineness and different-dye-uptake polyester low stretch yarn is 2.9cN/dtex, the elongation at break is 33.0 percent, the linear density deviation rate is 1.5 percent, the breaking strength CV value is 4.7 percent, the elongation at break CV value is 10.0 percent, the boiling water shrinkage rate is 5.5 percent, the oil content is 2.5 percent by weight, and the crimp shrinkage rate is 14.0 percent;

the dyeing rate of the polyester drawn textured yarn with different titer and different dyeing rate at the temperature of 120 ℃ is 89.3 percent, the soaping color fastness reaches 5 grade, the dry friction fastness reaches 5 grade, and the wet friction fastness reaches 5 grade;

the polyester low stretch yarn with different titer and different dye uptake is in a bamboo joint shape, and the length of the bamboo joint is 3.13 pieces/m.

Example 6

(1) preparing modified polyester;

(1.1) synthesizing 2,2,4, 4-tetramethyl-3, 4-di-tert-butyl-3, 4-hexanediol by the following steps: firstly, mixing a 2,24, 4-tetramethyl-3-pentanone solution with the concentration of 350g/L and a dilute sulfuric acid solution with the concentration of 220g/L according to the molar ratio of 2,24, 4-tetramethyl-3-pentanone to sulfuric acid of 2:1, adding the mixture into a cathode electrolytic cell, then cooling the mixed solution to 13 ℃, carrying out electrolytic reduction until the concentration of the 2,24, 4-tetramethyl-3-pentanone is 9.6 wt%, and finally carrying out cooling crystallization, separation and purification, wherein a reaction device and a reaction chemical equation adopted in the synthetic process are consistent with those of example 1, and the structural formula of the prepared 2,2,4, 4-tetramethyl-3, 4-di-tert-butyl-3, 4-hexanediol is shown as a formula (I), wherein R is-C (CH)₃)₃；

(1.2) esterification reaction;

preparing terephthalic acid, ethylene glycol and 2,2,4, 4-tetramethyl-3, 4-di-tert-butyl-3, 4-hexanediol with a molar ratio of 1:1.2:0.045 into slurry, adding antimony trioxide and trimethyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.2MPa, the esterification reaction temperature is 258 ℃, the esterification reaction end point is determined when the water distillation amount in the esterification reaction reaches 95% of a theoretical value, and the adding amounts of the antimony trioxide and the trimethyl phosphate are respectively 0.04 wt% and 0.01 wt% of the adding amount of the terephthalic acid;

(1.3) a polycondensation reaction;

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 absolute pressure of 430Pa within 35min, controlling the reaction temperature to 258 ℃, controlling the reaction time to be 40min, then continuously pumping vacuum, and carrying out the polycondensation reaction in a high vacuum stage, so that the reaction pressure is further reduced to absolute pressure of 94Pa, the reaction temperature is 280 ℃, the reaction time is 80min, the number average molecular weight of the prepared modified polyester is 29100, and the molecular weight distribution index is 1.9;

(2) preparing two modified polyester POY yarns with different filament numbers;

respectively carrying out metering, spinneret plate extrusion, cooling, oiling and winding on the modified polyester melt to obtain modified polyester POY (polyester pre-oriented yarn) with round cross sections and 0.7dtex and 2.5dtex of filament number respectively, wherein the parameters of the POY process are as follows: the spinning temperature is 283 ℃, the cooling temperature is 20 ℃, and the winding speed is 3600 m/min;

two modified polyester POY yarns with different filament titer are doubled and then processed according to a DTY process, the modified polyester POY yarns are subjected to the DTY process flow which is basically the same as that of the example 1 by adopting DTY equipment with the same structure as that of the example 1 to prepare the polyester low stretch yarns with different titer and different dye uptake, the DTY process is different from the example 1 in that the moving period of a frequency conversion yarn shifter is 75 reciprocating times/min, and the parameters of the DTY process are as follows: the spinning speed is 700m/min, the setting overfeed rate is 5.5 percent, the winding overfeed rate is 5.5 percent, the temperature of the first hot box is 200 ℃, the temperature of the second hot box is 150 ℃, and the drawing ratio is 1.2.

The titer ratio of the modified polyester POY yarn with larger monofilament titer to the modified polyester POY yarn with smaller monofilament titer in the finally prepared polyester low stretch yarn with different titer and different dye uptake is 1.5: 2; the breaking strength of the different-fineness and different-dye-uptake polyester low stretch yarn is 3.0cN/dtex, the elongation at break is 30.0 percent, the linear density deviation rate is 1.5 percent, the breaking strength CV value is 4.7 percent, the elongation at break CV value is 9.8 percent, the boiling water shrinkage rate is 5.1 percent, the oil content is 2.5 percent by weight, and the crimp shrinkage rate is 14.5 percent;

the dyeing rate of the polyester drawn textured yarn with different titer and different dyeing rate at the temperature of 120 ℃ is 91.4 percent, the soaping color fastness reaches 5 grade, the dry friction fastness reaches 5 grade, and the wet friction fastness reaches 5 grade;

the polyester low stretch yarn with different titer and different dye uptake is in a bamboo joint shape, and the length of the bamboo joint is 4.63 pieces/m.

Example 7

(1) preparing modified polyester;

(1.1) synthesizing 2,2,5, 5-tetramethyl-3, 4-hexanediol by the following steps: firstly, mixing a 2, 2-methylpropionaldehyde solution with the concentration of 340g/L and a dilute sulfuric acid solution with the concentration of 260g/L according to the molar ratio of the 2, 2-methylpropionaldehyde to sulfuric acid of 1.5:1, adding the mixture into a cathode electrolytic cell, then cooling the mixed solution to 13 ℃, carrying out electrolytic reduction to the concentration of the 2, 2-methylpropionaldehyde of 9.5 wt%, and finally carrying out cooling crystallization, separation and purification, wherein a reaction device and a reaction chemical equation adopted in the synthesis process are consistent with those of example 1, and the structural formula of the prepared 2,2,5, 5-tetramethyl-3, 4-hexanediol is shown as a formula (I), wherein R is-H;

(1.2) esterification reaction;

preparing terephthalic acid, ethylene glycol and 2,2,5, 5-tetramethyl-3, 4-hexanediol with a molar ratio of 1:2.0:0.05 into slurry, adding ethylene glycol antimony and triphenyl 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 ℃, the esterification reaction end point is when the water distillation amount in the esterification reaction reaches 91% of a theoretical value, and the addition amounts of the ethylene glycol antimony and the triphenyl phosphate are respectively 0.05 wt% and 0.05 wt% of the addition amount of the terephthalic acid;

(1.3) a polycondensation reaction;

after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, smoothly pumping the pressure in the stage from normal pressure to absolute pressure of 400Pa within 50min, controlling the reaction temperature to be 260 ℃ and the reaction time to be 50min, then continuing to pump vacuum, and carrying out the polycondensation reaction in a high vacuum stage to further reduce the reaction pressure to absolute pressure of 88Pa, control the reaction temperature to be 282 ℃ and control the reaction time to be 90min, wherein the number average molecular weight of the prepared modified polyester is 5000 and the molecular weight distribution index is 2.1;

(2) preparing two modified polyester POY yarns with different filament numbers;

respectively carrying out metering, spinneret plate extrusion, cooling, oiling and winding on the modified polyester melt to obtain modified polyester POY (polyester pre-oriented yarn) with round cross sections and 0.55dtex and 1.5dtex of filament number respectively, wherein the parameters of the POY process are as follows: the spinning temperature is 280 ℃, the cooling temperature is 20 ℃, and the winding speed is 3500 m/min;

two modified polyester POY yarns with different filament titer are doubled and then processed according to a DTY process, the modified polyester POY yarns are subjected to the DTY process flow which is basically the same as that of the example 1 by adopting DTY equipment with the same structure as that of the example 1 to prepare the polyester low stretch yarns with different titer and different dye uptake, the DTY process is different from the example 1 in that the moving period of a frequency conversion yarn shifter is 90 reciprocating times/min, and the parameters of the DTY process are as follows: the spinning speed is 700m/min, the setting overfeed rate is 3.5 percent, the winding overfeed rate is 5.0 percent, the temperature of the first hot box is 180 ℃, the temperature of the second hot box is 145 ℃, and the drawing ratio is 1.5.

The titer ratio of the modified polyester POY yarn with larger monofilament titer to the modified polyester POY yarn with smaller monofilament titer in the finally prepared polyester low stretch yarn with different titer and different dye uptake is 1.7: 2; the breaking strength of the different-fineness and different-dye-uptake polyester low stretch yarn is 2.8cN/dtex, the elongation at break is 34.0 percent, the linear density deviation rate is 1.38 percent, the breaking strength CV value is 4.85 percent, the elongation at break CV value is 9.8 percent, the boiling water shrinkage rate is 5.1 percent, the oil content is 2.8 percent by weight, and the crimp shrinkage rate is 14.0 percent;

the dyeing rate of the polyester drawn textured yarn with different titer and different dyeing rate at the temperature of 120 ℃ is 90.3 percent, the soaping color fastness reaches 5 grade, the dry friction fastness reaches 5 grade, and the wet friction fastness reaches 6 grade;

the polyester low stretch yarn with different titer and different dye uptake is in a bamboo joint shape, and the length of the bamboo joint is 5.53 pieces/m.

Claims

1. The preparation method of the polyester low stretch yarn with different titer and different dye uptake is characterized by comprising the following steps: doubling two modified polyester POY yarns with different filament deniers, processing the combined yarns according to a DTY process, arranging a groove breaking roller and a variable-frequency yarn shifter between a zero roller and a first roller of a DTY device, and passing modified polyester tows through the surface of the groove breaking roller to prepare the different-denier and different-dye-uptake polyester low stretch yarns;

the structural formula of hexanediol with tert-butyl side groups is as follows:

in the formula, R is-H, -CH₂CH₃or-C (CH)₃)₃；

the diameter of the end face of the groove breaking roller is 80 mm; the distance between two adjacent grooves is 6mm, and the distance between the two grooves on the outermost side in the central axis direction of the roller and the end of the roller closest to the grooves is 3.25 mm; the depth of the grooves is 2.6mm, the width is 4mm, and the number of the grooves is 4; the moving period of the variable-frequency wire moving device is 5-99 reciprocating times/min;

the temperature of a second hot box of the DTY process is 130-150 ℃.

2. The method for preparing the differential titer and different dye uptake polyester drawn textured yarn as claimed in claim 1, wherein the filament titer of the two modified polyester POY yarns with different filament titer is 0.5-0.7 dtex and 1.5-2.5 dtex respectively, and the titer ratio of the modified polyester POY yarn with larger filament titer to the modified polyester POY yarn with smaller filament titer in the differential titer and different dye uptake polyester drawn textured yarn is 1-2: 1-2.

3. The method for preparing the different-denier and different-dye-uptake polyester drawn textured yarn as claimed in claim 1, wherein the different-denier and different-dye-uptake polyester drawn textured yarn has breaking strength of more than or equal to 2.8cN/dtex, elongation at break of 33.0 +/-3.0%, linear density deviation rate of less than or equal to 1.5%, breaking strength CV value of less than or equal to 5.0%, elongation at break CV value of less than or equal to 10.0%, boiling water shrinkage of 5.9 +/-0.8%, oil content of 2.50 +/-0.50 wt%, and crimp shrinkage of 14.0 +/-0.5%; the dyeing rate of the different-titer and different-dyeing-rate polyester low stretch yarn at the temperature of 120 ℃ is 87.3-91.4%, the soaping-resistant color fastness reaches 5 grade, the dry friction fastness reaches 5 grade, and the wet friction fastness is higher than 4 grade; the different-titer and different-dye-uptake polyester low stretch yarn is in a bamboo joint shape, and the length of the bamboo joint is 0.31-5.80 pieces/m.

4. The method for preparing the differential denier and differential dye uptake polyester drawn textured yarn as claimed in claim 1, wherein the cross section of the two modified polyester POY yarns with different filament deniers is circular.

5. The method for preparing the differential titer and dye uptake polyester drawn textured yarn as claimed in claim 1, wherein the synthesis method of the hexanediol with the tertiary butyl side group is as follows: firstly, mixing a raw material solution A with the concentration of 300-350 g/L and a dilute sulfuric acid solution with the concentration of 200-300 g/L according to the molar ratio of the raw material A to sulfuric acid of 1.5-2: 1, adding the mixture into a cathode electrolytic cell, then cooling the mixed solution to 10-15 ℃, carrying out electrolytic reduction until the concentration of the raw material A is lower than 10 wt%, and finally carrying out cooling crystallization, separation and purification;

6. The method for preparing the differential titer and dye uptake polyester drawn textured yarn as claimed in claim 5, wherein the modified polyester is prepared by the following steps:

(1) performing esterification reaction;

(2) performing polycondensation reaction;

7. The method for preparing the different-titer and different-dye-uptake polyester drawn textured yarn as claimed in claim 6, wherein the molar ratio of the terephthalic acid to the ethylene glycol to the hexanediol with the tert-butyl side group is 1: 1.2-2.0: 0.03-0.05, and the addition amounts of the catalyst and the stabilizer are 0.03-0.05 wt% and 0.01-0.05 wt% of the addition amount of the terephthalic acid respectively.

8. The method for preparing the different-denier different-dye-uptake polyester drawn textured yarn as claimed in claim 7, wherein the catalyst is antimony trioxide, ethylene glycol antimony or antimony acetate, and the stabilizer is triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.

9. The method for preparing the different-titer and different-dye-uptake polyester drawn textured yarn as claimed in claim 8, wherein the number average molecular weight of the modified polyester is 25000-30000, and the molecular weight distribution index is 1.8-2.2.

10. The method for preparing the differential titer and dye uptake polyester drawn textured yarn as claimed in claim 1, wherein the POY process comprises the following steps: metering, spinneret plate extrusion, cooling, oiling and winding;