CN103147163B - Skin-core type recycled polyester staple fiber and preparation method thereof - Google Patents

Abstract

The invention relates to a skin-core regenerated polyester staple fiber and a preparation method thereof. The regenerated polyester staple fiber is composed of a skin layer and a core layer, and the skin layer is a low-melting point regenerated polyester, and the melting point of the low-melting point regenerated polyester is 70-160°C , carboxyl-terminal content≤35mmol/kg, intrinsic viscosity is 0.5dL/g～1.OdL/g; the core layer is high-melting point regenerated polyester, the melting point of the high-melting point regenerated polyester is 250-270°C, and the carboxyl-terminal The content is ≤20mmol/kg, and the intrinsic viscosity is 0.7dl/g～1.0dl/g; the two polyester melts are metered by their respective metering pumps and then enter the composite spinneret assembly, and the melts ejected from the spinneret of the composite assembly , After cooling, winding, bundling, drafting, shaping, cutting and packaging, sheath-core recycled polyester staple fibers can be obtained. The sheath-core type regenerated polyester staple fiber prepared by the method of the invention has stable and excellent quality.

Description

A kind of sheath-core type regenerated polyester staple fiber and preparation method thereof

technical field

The invention relates to the technical field of chemical fiber production, in particular to a sheath-core regenerated polyester staple fiber and a preparation method thereof.

Background technique

Low-melting point sheath-core composite polyester staple fiber refers to the fiber made of two different polymers, low-melting point polyester and conventional polyester, which are distributed in the same fiber in a sheath-core structure. The cortex is a low-melting polyester, which retains some of the properties of conventional polyesters and has good compatibility with conventional polyesters. The low-melting point skin-core composite fiber is mainly used for thermal bonding fibers. The main function in the production of nonwovens is to melt the low-melting point fiber skin layer polymer at a certain temperature, thereby playing a bonding effect in the fiber web. Due to the low-melting point polyester staple fiber has high strength, good bulkiness, and high elastic recovery rate, the nonwoven fabric produced has the characteristics of soft hand feeling and high elasticity. It is currently widely used in surgical masks, bandages and other sanitary materials and interior decoration materials. field.

At present, there are many research reports on the production method of low melting point polyester staple fiber. For example, the invention patent "a low melting point copolyester and its preparation method" (application number: 200810063395.4) discloses the design method of the low melting point copolyester, the melting point of the polyester can be reduced to 110°C, and the low melting point copolyester crystallizes Good performance, high intrinsic viscosity, not easy to stick particles, good spinnability, etc. Invention patent "A Production Method of Low-melting Polyester Staple Fiber" (Application No.: 200410072878.2) uses low-melting-point polyester chips at 120°C to 130°C to vacuum-dry at low temperature and then melt-spins to obtain low-melting point staple fibers. The invention patent "a side-by-side composite low-melting-point short fiber" (application number: 200810123792.6) discloses a low-melting-point short fiber composed of water-soluble polyester components and polytrimethylene terephthalate components side by side. The fiber has good thermal shrinkage stability. There are also some reports on the research on low-melting point sheath-core composite polyester fibers. For example, the invention patent "A Production Method of Sheath-Core Low-melting Polyester Staple Fiber" (Application No.: 200810163542.5) is characterized in that the skin layer is a low-melting point polyester melt obtained by melt direct spinning, and the core layer is made of conventional PET. Conventional PET polyester melt obtained by chip spinning process. However, there is no report on the use of recycled materials to prepare polyester staple fibers as the core layer of sheath-core composite fibers.

With the rapid development and use of polyester materials in various fields, the discharge of polyester waste is increasing day by day, and its refractory property has caused great pollution to the environment. Recycling has become a need for a sustainable society. At present, most of the staple fibers prepared from polyester waste are used in low-additional fields such as fillers. Studying the tempering and viscosity adjustment process, solving the technical problems of wide sources of polyester waste, complex components, and large quality fluctuations, and using polyester waste to prepare products with high added value has become a major issue in the transformation and upgrading of the recycling industry. In addition, this technology replaces low-melting polyester chip spinning with melt direct spinning, which better solves a series of problems such as high drying cost, poor stability, and poor fiber spinnability of low-melting polyester, and the production cost is greatly reduced.

Contents of the invention

In order to solve the technical problems of using recycled materials to prepare polyester sheath-core composite fibers, an object of the present invention is to provide a method for preparing sheath-core regenerated polyester staple fibers, which improves the efficiency of the preparation of regenerated polyester from polyester waste. The added value of the staple fiber, the prepared sheath-core type recycled polyester staple fiber has the characteristics of stable quality and excellent quality. Another object of the present invention is to provide recycled polyester staple fibers prepared by the above method.

In order to achieve the above-mentioned first purpose, the present invention adopts the following technical solutions:

A method for preparing sheath-core regenerated polyester staple fibers, the regenerated polyester staple fibers are composed of a cortex and a core, the cortex accounts for 10% to 90% of the total weight of the composite fiber, and the core is completely wrapped in the cortex; The cortex is a low melting point recycled polyester prepared by degradation, modification and polymerization of recycled materials. The melting point of the low melting point recycled polyester is 70-160°C, the content of terminal carboxyl groups is ≤35 mmol/kg, and the intrinsic viscosity is 0.5dL/g-1. OdL/g; the core layer is a high-melting point regenerated polyester prepared from regenerated materials through a tempering and viscosity-adjusting process. The melting point of the high-melting point regenerated polyester is 250-270°C, the carboxyl-terminal content is ≤20mmol/kg, and the intrinsic viscosity is 0.7dl/g～1.0 dl/g; the two polyester melts are metered by their respective metering pumps and then enter the composite spinneret assembly, and the melts ejected from the spinneret of the composite assembly are cooled, wound, clustered, Drawing, setting, cutting and packing can obtain sheath-core recycled polyester staple fiber.

Preferably, the intrinsic viscosity of the regenerated low-melting polyester is 0.55dL/g-0.75dL/g, and the intrinsic viscosity of the regenerated high-melting polyester is 0.75dl/g-0.85dl/g.

Preferably, the regenerated low-melting polyester is prepared from the following raw materials through degradation and polycondensation:

a. Recycled raw materials;

b. Methanol, water or ethylene glycol;

c. One or more of zinc acetate, potassium acetate, manganese acetate, magnesium acetate, lead acetate, cobalt chloride, tetrabutyl titanate, tetraisopropyl titanate and butyltin laurate;

d. One or more of isophthalic acid, adipic acid and sebacic acid;

e. One or more of neopentyl glycol, hexanediol, butanediol and polyethylene glycol;

f. Catalyst antimony trioxide and cobalt acetate;

g. stabilizer trimethyl phosphate;

Select one of the following methods to prepare recycled low-melting polyester according to b raw materials:

1. Methanol alcoholysis

1) Mix a, b and c after feeding, the mass ratio of a and b is 1:4~14, the mass ratio of a and c is 100:0.5~1; the degradation temperature is 170~250°C, and the pressure is 1.5 ～4.0Mpa, the reaction time is 2.5～5h, when the pressure returns to the atmospheric pressure, the reaction is completed, the reactant is filtered, the obtained liquid is rotary evaporated, methanol and ethylene glycol are evaporated separately, and the obtained solid is dissolved in hot ethanol and filtered , the obtained liquid evaporates ethanol to obtain dimethyl terephthalate;

2) The esterification reaction of dimethyl terephthalate and ethylene glycol is carried out under nitrogen pressure, and the molar ratio of dimethyl terephthalate to d is 2 to 5:1; dimethyl terephthalate The molar ratio of ester to e is 3-19:1; the molar ratio of dimethyl terephthalate to ethylene glycol is 20:80-80:20; the molar ratio of alkyd is 1.4-1.6:1; The feeding of f and g is 200-600ppm of the total amount of acid, and the alcohol is the sum of ethylene glycol and e; the temperature of the esterification reaction is 180-250°C, the pressure is 0.05MPa-0.4MPa, and the reaction time is 1.5- 3h; polycondensation reaction temperature is 250~285℃, vacuum degree is 30~200Pa, reaction time is 2.5~5h;

2. Hydrolysis

1) Hydrolysis: mix a, b and c after feeding, the mass ratio of a and b is 1:1~5, the mass ratio of a and c is 100:0.5~1; the reaction temperature is 190~280℃, the pressure 3.0 ~ 6.0Mpa, the reaction time is 2 ~ 5h, after the reaction is completed and the pressure returns to atmospheric pressure, the reactant is filtered, the obtained liquid is rotary evaporated to obtain ethylene glycol, and then the filtered solid is dissolved in DMF and filtered, and the obtained liquid weighs Crystallization gives terephthalic acid;

2) The esterification reaction of terephthalic acid and ethylene glycol is carried out under nitrogen pressure, and the molar ratio of terephthalic acid to d is 2 to 5:1; the molar ratio of terephthalic acid to e is 3 ～19:1; the molar ratio of terephthalic acid to ethylene glycol: 20:80～80:20; the molar ratio of alkyd is 1.4～1.6:1; the feed of f and g is 200～600ppm of acid; The alcohol is the sum of ethylene glycol and e, the acid is the sum of terephthalic acid and d; the temperature of the esterification reaction is 180-250°C, the pressure is 0.05MPa～0.4MPa, and the reaction time is 1.5～ 3h; the polycondensation reaction temperature is 250-285°C, the vacuum degree is 30-200Pa, and the reaction time is 2.5-5h;

3. Ethylene glycol alcoholysis method

1) Mix a, b, and c after feeding. The mass ratio of a to b is 1:1~4; the mass ratio of a to c is 100:0.5~1; it is carried out under nitrogen pressure or normal pressure. The reaction temperature is 170-220°C, the pressure is 0°C 0.4MPa, and the reaction time is 1.5-3h until the intrinsic viscosity of the reaction solution reaches 0.2-0.35dl/g; Recover ethylene glycol by vacuum distillation, dissolve the liquid after vacuum distillation in hot alcohol, ester, chlorinated hydrocarbon or ketone solvent, heat filter to remove insoluble matter, and naturally cool the filtrate to obtain ethylene terephthalate and its Oligomer;

2) Polycondensation reaction of ethylene terephthalate and its oligomers, the molar mass of d is the mass of a/960-mass of a/384; the molar mass of e is the mass of a/1728-a mass/576; the molar ratio of alkyd is 1.4～1.6:1; the feeding of f and g is 200～600ppm of the total amount of acid, the reaction temperature is 250～285℃, the vacuum degree is 30～200Pa, and the reaction time is 2.5～ 5h.

As a further improvement, the recycled polyester raw materials mainly made of polyester bottle flakes are prepared through a tempering and viscosity-adjusting process. The specific process is as follows: recycled raw materials—cleaning—proportioning—drum drying—multistage filtration— Viscosification in liquid phase, wherein the drum drying temperature is 100~150℃, and the drying time is 7~10h.

As a further improvement, the steps of the liquid-phase thickening are as follows:

1) After being melted by the screw, the temperature is 260°C~290°C and the melt with an intrinsic viscosity of 0.5dl/g~0.70dl/g is pumped to the vacuum separation tower through the melt conveying pump, and the vacuum degree of the melt is 10pa~400pa. The temperature is 270°C~300°C, and the intrinsic viscosity can reach 0.55dl/g~0.78dl/g after staying for 15min~40min under the condition;

2) After that, the melt enters the secondary tempering and viscosity adjusting device. The melt temperature and vacuum degree in the secondary tempering and viscosity adjusting device are the same as those in the vacuum separation tower. Under the action of the rotating propeller, the melt continues to advance, and the melt viscosity Continuously increasing, the rotation speed of the propeller is 1.5r/min~10r/min, the residence time is 15min~30min, and the final intrinsic viscosity of the melt is 0.60dl/g~0.88dl/g.

The liquid-phase viscosity-increasing process of the present invention adopts a waste plastic conditioning and viscosity-adjusting system described in the Chinese invention patent (application number: 201010574044.7, application date: 2010-12-01).

As a further improvement, the recycled polyester raw materials also include mixed waste polyester textiles.

The control of spinning temperature is the key to the production of low-melting sheath-core composite staple fiber. The different material characteristics of the sheath and core should be considered, and different temperature controls should be adopted for the temperature of the pipe and box of the two components. After the two melts are combined in the main box, they should be controlled according to the temperature that both can adapt to. As a further improvement, the heat preservation temperature of the low-melting polyester spinning pipe is 220-240°C; the screw temperature of the recycled polyester is 270-300°C, the heat preservation temperature of the regenerated polyester spinning pipe is 270-290°C, and the spinning box The body temperature is 270-290°C.

The thin stream of composite melt is in the spinning shaft, and after being cooled by blowing, the viscosity of the melt gradually increases until it is solidified and formed. If the cooling is not sufficient, the primary fibers will be in a molten state after exiting the spinneret hole due to the low melting point of the cortex, and will stick together. As a further improvement, the cooling is carried out by circular air blowing, the air temperature is 15-32° C., the wind speed is 0.5-5.0 m/s, and the spinning speed is 800-1200 m/min.

As a further improvement, the drawing ratio of the drawing is 1.2-3.5, the drawing temperature is 50-72° C., and the drawing speed is 100-150 m/min.

In order to achieve the above-mentioned second object, the present invention also provides the regenerated polyester staple fiber prepared by the above-mentioned preparation method.

The sheath-core regenerated polyester staple fiber prepared by the method of the invention has stable quality and good quality, and can be used in industries such as production of non-woven fabrics, flocking, and composite materials.

Detailed ways

Example 1

1. Preparation of recycled low-melting point polyester: the mass ratio of recycled raw materials to methanol is 1:6; the mass ratio of recycled raw materials to zinc acetate is 100:0.5; the above raw materials are polymerized after methanolysis to prepare recycled low-melting point polyester : The degradation temperature is 190°C, the pressure is 2.5Mpa, and the reaction time is 3h. When the pressure returns to atmospheric pressure, the reaction is completed. The reactant is filtered, the obtained liquid is rotary evaporated, methanol and ethylene glycol are evaporated separately, and the obtained solid Dissolve in hot ethanol and filter, and distill off the ethanol from the resulting liquid to obtain dimethyl terephthalate (DMT). The molar ratio of dimethyl terephthalate (DMT) to isophthalic acid (IPA) is 3:1; the molar ratio of dimethyl terephthalate (DMT) to neopentyl glycol (NPG) is 7:1; 1:2 molar ratio of dimethyl terephthalate (DMT) to ethylene glycol; 1.5:1 molar ratio of alcohol (sum of ethylene glycol and neopentyl glycol (NPG)) acid ; Catalyst antimony trioxide (Sb203) and cobalt acetate (Co(Ac) 2) are 300ppm of acid total amount in the reaction system, then add the stabilizing agent trimethyl phosphate (TMP ). The esterification reaction was carried out under nitrogen pressure, the temperature was 220°C, the pressure was 0.15MPa, and the reaction time was 2.2h; the polycondensation reaction temperature was 275°C, the vacuum degree was 90Pa, and the reaction time was 3.5h. The obtained low-melting-point polyester had a melting point of 110° C., a carboxyl-terminated content of 25 mmol/kg, and an intrinsic viscosity of 0.69 dL/g.

2. Preparation of recycled polyester: The technological process of washing bottle flakes, drum drying, multi-stage filtration, and liquid-phase thickening is adopted. Wherein, the drum drying temperature is 130° C., and the drying time is 8 hours. The steps of liquid phase viscosification are as follows: 1) The temperature after melting by the screw is at 270°C. The melt with an intrinsic viscosity of 0.55dl/g is pumped to the vacuum separation tower through the melt delivery pump. The melt is at a vacuum degree of 100pa and the temperature is After staying at 280°C for 30 minutes, the intrinsic viscosity can reach 0.68dl/g; 2) After that, the melt enters the secondary tempering and viscosity regulating device, and the melt temperature and vacuum degree in the secondary tempering and viscosity regulating device are the same as those in the vacuum separation tower Similarly, under the action of the rotating propeller, the melt advances continuously, and the viscosity of the melt increases continuously. The rotation speed of the propeller is 5r/min, the residence time is 20min, and the final intrinsic viscosity of the melt is 0.79dl/g. The melting point of the recycled polyester is 264°C, the carboxyl-terminated content is 16 mmol/kg, and the intrinsic viscosity is 0.79dl/g.

3. Sheath-core regenerated polyester staple fiber: the above-mentioned low-melting point polyester and regenerated polyester are accurately metered into the composite spinneret assembly with 4:6 sheath-core weight respectively, and the melt ejected from the spinneret of the composite assembly , After cooling, winding, bundling, drafting, shaping, cutting and packaging, sheath-core recycled polyester staple fibers can be obtained. The drying temperature of recycled polyester is 150°C, the drying time is 7 hours, the screw temperature is 280°C; the insulation temperature of low-melting polyester spinning pipe is 230°C, the insulation temperature of recycled polyester spinning pipe is 275°C, and the spinning box temperature 280°C; the cooling air temperature of the ring blower is 15°C, the wind speed is 2.0m/s; the spinning speed is 1100m/min; the draw ratio is 2.0, the drawing temperature is 60°C, and the drawing speed is 110m/min. The sheath-core type regenerated polyester staple fiber quality index that obtains through above-mentioned production process is:

Line density: 4.21dtex

Breaking strength: 3.14cN/dtex

Elongation at break: 40%

Cut length: 51.2mm.

Example 2

1. Preparation of recycled low melting point polyester: The mass ratio of recycled raw materials to water is 1:4; the mass ratio of recycled raw materials to potassium acetate is 100:0.5; the above raw materials are hydrolyzed and polymerized to prepare recycled low melting point polyester: hydrolysis The temperature is 220°C, the pressure is 4.5Mpa, and the reaction time is 2.8h. When the reaction is completed and the pressure returns to atmospheric pressure, the reactant is filtered, and the obtained liquid is rotary evaporated to obtain ethylene glycol, and then the filtered solid is dissolved in DMF and filtered. The resulting liquid is recrystallized to give terephthalic acid (TPA). The molar ratio of terephthalic acid (TPA) to adipic acid (AA) is 3.5:1; the molar ratio of terephthalic acid (TPA) to hexanediol (HG) is 6:1; terephthalic acid The molar ratio of (TPA) to ethylene glycol is 1.5:1; the molar ratio of alkyd is 1.5:1; the catalyst is antimony trioxide (Sb203) and cobalt acetate (Co(Ac)2) as the total amount of acid in the reaction system 300ppm, and then add a stabilizer trimethyl phosphate (TMP) with a weight of 0.01% (relative to the acid content). The esterification reaction is carried out under nitrogen pressure, the temperature is 220°C, the pressure is 0.3MPa, and the reaction time is 2.5h; the polycondensation reaction temperature is 275°C, the vacuum degree is 80Pa, and the reaction time is 3h. The melting point of the obtained low melting point polyester is At 105°C, the carboxyl-terminated content is 28mmol/kg, and the intrinsic viscosity is 0.67dL/g.

2. Preparation of recycled polyester: The technological process of washing bottle flakes, drum drying, multi-stage filtration, and liquid-phase thickening is adopted. Wherein, the drum drying temperature is 110° C., and the drying time is 7 hours. The steps of liquid phase viscosification are as follows: 1) The temperature after melting by the screw is at 270°C. The melt with an intrinsic viscosity of 0.55dl/g is pumped to the vacuum separation tower through the melt delivery pump. The melt is at a vacuum degree of 100pa and the temperature is After staying at 280°C for 30 minutes, the intrinsic viscosity can reach 0.68dl/g; 2) After that, the melt enters the secondary tempering and viscosity regulating device, and the melt temperature and vacuum degree in the secondary tempering and viscosity regulating device are the same as those in the vacuum separation tower Similarly, under the action of the rotating propeller, the melt advances continuously, and the viscosity of the melt increases continuously. The rotation speed of the propeller is 5r/min, the residence time is 15min, and the final intrinsic viscosity of the melt is 0.78dl/g. The melting point of the recycled polyester is 269°C, the carboxyl-terminated content is 14 mmol/kg, and the intrinsic viscosity is 0.78dl/g.

3. Sheath-core regenerated polyester staple fiber: the above-mentioned low-melting point polyester and regenerated polyester are accurately metered into the composite spinneret with a skin-core weight of 5:5, and the melt ejected from the spinneret of the composite assembly , After cooling, winding, bundling, drafting, shaping, cutting and packaging, sheath-core recycled polyester staple fibers can be obtained. The drying temperature of the recycled polyester raw material is 140°C, the drying time is 7.5 hours, the screw temperature is 270°C; the heat preservation temperature of the low-melting point polyester spinning pipe is 220°C, the heat preservation temperature of the recycled polyester spinning pipe is 275°C, the spinning box The body temperature is 280°C; the cooling air temperature of the ring blower is 20°C, the wind speed is 3.0m/s; the spinning speed is 1000m/min; the draw ratio is 3.0, the drawing temperature is 56°C, and the drawing speed is 120m/min. The sheath-core type regenerated polyester staple fiber quality index that obtains through above-mentioned production process is:

Line density: 4.05dtex

Breaking strength: 3.22cN/dtex

Elongation at break: 42%

Cut length: 51.6mm.

Example 3

1. Preparation of recycled low-melting polyester: the mass ratio of recycled raw materials to ethylene glycol is 1:3.5; the mass ratio of recycled raw materials to butanediyltin laurate is 100:0.5; the alcoholysis reaction temperature is 196°C, The pressure is 0.15MPa, the reaction time is 2h, and the intrinsic viscosity of the reaction liquid reaches 0.29dl/g. After the reaction is finished, quickly heat the reaction liquid and filter it, carry out vacuum distillation on the filtrate to recover ethylene glycol, and dissolve the liquid (solid at normal temperature) after vacuum distillation in solvents such as hot alcohol, ester, chlorinated hydrocarbon, ketone, etc. , heat filtered to remove insoluble matter, and the filtrate was naturally cooled to obtain ethylene terephthalate (BHET) and its oligomers. Add isophthalic acid (IPA), neopentyl glycol (NPG), catalyst antimony trioxide (Sb203) and cobalt acetate (Co(Ac) to ethylene terephthalate (BHET) and its oligomers. )2) and the stabilizer trimethyl phosphate (TMP) for polycondensation reaction, the polycondensation reaction temperature of ethylene terephthalate (BHET) and its oligomers is 275°C, the vacuum degree is 95Pa, and the reaction time is 3.5 h. The obtained low-melting-point polyester had a melting point of 115° C., a carboxyl-terminated content of 30 mmol/kg, and an intrinsic viscosity of 0.68 dL/g. The molar amount of isophthalic acid (IPA) is the mass of recycled raw materials/450; the molar amount of neopentyl glycol (NPG) is the mass of recycled raw materials/960; the molar ratio of alkyd is 1.4; the catalyst is antimony trioxide (Sb203) and cobalt acetate (Co(Ac)2) are 400ppm of the total amount of acid in the reaction system, and then add a stabilizer trimethyl phosphate (TMP) with a weight of 0.01% (relative to the acid component).

2. Preparation of recycled polyester: The technological process of washing bottle flakes, drum drying, multi-stage filtration, and liquid-phase thickening is adopted. Wherein, the drum drying temperature is 100° C., and the drying time is 7 hours. The steps of liquid phase viscosification are as follows: 1) The temperature after melting by the screw is at 270°C. The melt with an intrinsic viscosity of 0.55dl/g is pumped to the vacuum separation tower through the melt delivery pump. The melt is at a vacuum degree of 100pa and the temperature is After staying at 280°C for 30 minutes, the intrinsic viscosity can reach 0.68dl/g; 2) After that, the melt enters the secondary tempering and viscosity regulating device, and the melt temperature and vacuum degree in the secondary tempering and viscosity regulating device are the same as those in the vacuum separation tower Similarly, under the action of the rotating propeller, the melt advances continuously, and the viscosity of the melt increases continuously. The rotation speed of the propeller is 5r/min, the residence time is 15min, and the final intrinsic viscosity of the melt is 0.78dl/g. The melting point of the recycled polyester is 267°C, the carboxyl-terminated content is 16 mmol/kg, and the intrinsic viscosity is 0.78dl/g.

3. Sheath-core regenerated polyester staple fiber: the above-mentioned low-melting point polyester and regenerated polyester are accurately metered into the composite spinneret by 6:4 sheath-core weight respectively, and the melt ejected from the spinneret of the composite assembly , After cooling, winding, bundling, drafting, shaping, cutting and packaging, sheath-core recycled polyester staple fibers can be obtained. The drying temperature of the recycled polyester raw material is 140°C, the drying time is 7 hours, and the screw temperature is 280°C; the heat preservation temperature of the low-melting polyester spinning pipe is 230°C, and the heat preservation temperature of the recycled polyester spinning pipe is 270°C. The temperature is 285°C; the cooling air temperature of the surrounding blower is 22°C, the wind speed is 2.5m/s; the spinning speed is 900m/min; the draw ratio is 2.5, the drawing temperature is 58°C, and the drawing speed is 110m/min. The sheath-core type regenerated polyester staple fiber quality index that obtains through above-mentioned production process is:

Linear density: 4.24 dtex

Breaking strength: 2.67 cN/dtex

Elongation at break: 47%

Cut length: 50.8mm.

Claims (8)

1. a preparation method for core-skin type regenerative polyester staple fiber, this regenerative polyester staple fiber is made up of cortex and sandwich layer, and cortex weight accounts for 10% ~ 90% of composite fibre gross weight, and sandwich layer is completely wrapped in cortex; It is characterized in that: cortex is that reworked material passes through to degrade again low melting point recycled polyester prepared by modified poly, and the fusing point of low melting point recycled polyester is 70 ~ 160 DEG C, content of carboxyl end group≤35mmol/kg, and inherent viscosity is 0.5dL/g ~ 1.0dL/g; Sandwich layer is the high-melting-point recycled polyester that reworked material is prepared by modified tune adhering process, and the fusing point of described high-melting-point recycled polyester is 250 ~ 270 DEG C, content of carboxyl end group≤20mmol/kg, and inherent viscosity is 0.7dl/g ~ 1.0dl/g; Two kinds of polyester fondants, by entering composite spinneret pack, the melt sprayed from the spinnerets of composite component after respective measuring pump metering, through cooling, winding, boundling, drawing-off, sizing, cut-out and packing, can obtain sheath-core type low-melting point regenerative polyester staple fiber;

Described low melting point recycled polyester is for following raw material is by degraded and polycondensation reaction and obtaining:

A. regenerative raw materials;

B. methyl alcohol, water or ethylene glycol;

C. one or more in base tin laurate of zinc acetate, potassium acetate, manganese acetate, magnesium acetate, lead acetate, cobalt chloride, butyl titanate, tetraisopropyl titanate and fourth two;

D. M-phthalic acid, one or more in adipic acid and decanedioic acid;

E. neopentyl glycol, hexylene glycol, one or more in butanediol and polyethylene glycol;

F. the catalytic antimony trioxide and cobalt acetate;

G. stabilizing agent trimethyl phosphate;

Following a kind of method preparation regeneration low-melting point polyester is selected according to b raw material:

One, Methanolysis method

1) mix after a, b and c being fed intake, the mass ratio that feeds intake of a and b is 1:4 ~ 14, and the mass ratio of a and c is 100:0.5 ~ 1; Degradation temperature is 170 ~ 250 DEG C, pressure is 1.5 ~ 4.0Mpa, reaction time is 2.5 ~ 5h, equal pressure reacts when getting back to atmospheric pressure and terminates, filtered by reactant, the liquid in rotation evaporation obtained, boils off methyl alcohol and ethylene glycol respectively, the solids obtained is dissolved in hot ethanol and filters, and gained liquid boils off ethanol and obtains dimethyl terephthalate (DMT);

2) esterification of dimethyl terephthalate (DMT) and ethylene glycol is carried out under nitrogen pressurization, and the molar ratio of dimethyl terephthalate (DMT) and d is 2 ~ 5:1; The molar ratio of dimethyl terephthalate (DMT) and e is 3 ~ 19:1; The mol ratio of dimethyl terephthalate (DMT) and ethylene glycol is: 20:80 ~ 80:20; The molar ratio of alkyd is 1.4 ~ 1.6:1; F and g feeds intake as 200 ~ 600ppm of sour total amount, and described alcohol is the summation of ethylene glycol and e; The temperature of esterification is 180 ~ 250 DEG C, and pressure is 0.05MPa ~ 0.4MPa, reaction time 1.5 ~ 3h; Polycondensation reaction temperature is 250 ~ 285 DEG C, and vacuum is 30 ~ 200Pa, reaction time 2.5 ~ 5h;

Two, Hydrolyze method

1) be hydrolyzed: mix after a, b and c being fed intake, the mass ratio that feeds intake of a and b is 1:1 ~ 5, and the mass ratio of a and c is 100:0.5 ~ 1; Reaction temperature is 190 ~ 280 DEG C, pressure is 3.0 ~ 6.0Mpa, reaction time is 2 ~ 5h, when reaction end equal pressure gets back to atmospheric pressure, reactant is filtered, the evaporation of gained liquid in rotation obtains ethylene glycol, then is dissolved in DMF by filtering solids thing and filters, and gained liquid recrystallization obtains terephthalic acid (TPA);

2) esterification of terephthalic acid (TPA) and ethylene glycol is carried out under nitrogen pressurization, and the molar ratio of terephthalic acid (TPA) and d is 2 ~ 5:1; The molar ratio of terephthalic acid (TPA) and e is 3 ~ 19:1; The mol ratio of terephthalic acid (TPA) and ethylene glycol is: 20:80 ~ 80:20; The molar ratio of alkyd is 1.4 ~ 1.6:1; F and g feeds intake as 200 ~ 600ppm of acid; Described alcohol is the summation of ethylene glycol and e, and described acid is the summation of terephthalic acid (TPA) and d; The temperature of esterification is 180 ~ 250 DEG C, and pressure is 0.05MPa ~ 0.4MPa, reaction time 1.5 ~ 3h; Polycondensation reaction temperature is 250 ~ 285 DEG C, and vacuum is 30 ~ 200Pa, reaction time 2.5 ~ 5h;

Three, glycolysis method

1) mix after a, b and c being fed intake, the mass ratio that feeds intake of a and b is 1:1 ~ 4; The mass ratio of a and c is 100:0.5 ~ 1; Carry out under nitrogen pressurization or condition of normal pressure, reaction temperature is 170 ~ 220 DEG C, and pressure is 0 DEG C of 0.4MPa, and the reaction time is 1.5 ~ 3h, until the inherent viscosity of reactant liquor reaches 0.2 ~ 0.35dl/g; After reaction terminates, reactant liquor Rapid Thermal is filtered, decompression distillation is carried out to filtrate and reclaims ethylene glycol, the liquid after decompression distillation is dissolved in hot alcohol, ester, chlorinated hydrocabon or ketone solvent, heat filtering goes out insoluble matter, and filtrate naturally cools and obtains ethylene glycol terephthalate and oligomer thereof;

2) polycondensation reaction of ethylene glycol terephthalate and oligomer thereof, the molar weight that feeds intake of d is quality/384 of the quality/960 ~ a of a; The molar weight that feeds intake of e is quality/576 of the quality/1728 ~ a of a; The molar ratio of alkyd is 1.4 ~ 1.6:1; F and g feeds intake as 200 ~ 600ppm of sour total amount, and reaction temperature is 250 ~ 285 DEG C, and vacuum is 30 ~ 200Pa, reaction time 2.5 ~ 5h.

2. the preparation method of a kind of core-skin type regenerative polyester staple fiber according to claim 1, is characterized in that the inherent viscosity of low melting point recycled polyester is 0.55dL/g ~ 0.75dL/g, and the inherent viscosity of high-melting-point recycled polyester is 0.75dl/g ~ 0.85dl/g.

3. the preparation method of a kind of core-skin type regenerative polyester staple fiber according to claim 1, it is characterized in that: the Pillar recovery raw material of recycled polyester based on polyester bottle slice is by modified tune adhering process preparation, concrete technology is as follows: regenerative raw materials-cleaning-proportioning-drum dried-multistage filtering-liquid-phase tackifying, wherein, drum dried temperature is 100 ~ 150 DEG C, and drying time is 7 ~ 10h.

4. the preparation method of a kind of core-skin type regenerative polyester staple fiber according to claim 3, is characterized in that the step of liquid-phase tackifying is as follows:

1) melt that the temperature after screw rod melting is 0.5dl/g ~ 0.70dl/g 260 DEG C ~ 290 DEG C inherent viscosities is pumped to vacuum separation tower through melt Conveying, melt is 10pa ~ 400pa in vacuum, temperature is 270 DEG C ~ 300 DEG C, and after stopping 15min ~ 40min under condition, inherent viscosity can reach 0.55dl/g ~ 0.78dl/g;

2) after, melt enters the modified tune of secondary and glues device, the melt temperature that the modified tune of secondary glues in device is identical with vacuum separation tower with vacuum, under the effect of rotatable propeller, melt constantly advances, melt viscosity constantly increases, angle of rake rotary speed is 1.5r/min ~ 10r/min, time of staying 15min ~ 30min, final melt characteristic viscosity is at 0.60dl/g ~ 0.88dl/g.

5. the preparation method of a kind of core-skin type regenerative polyester staple fiber according to claim 1, is characterized in that: low-melting point polyester spinning pipeline holding temperature is 220 ~ 240 DEG C; The extruder temperature of recycled polyester 270 ~ 300 DEG C, recycled polyester spinning pipeline holding temperature is 270 ~ 290 DEG C, and spinning body temperature is 270 ~ 290 DEG C.

6. the preparation method of a kind of core-skin type regenerative polyester staple fiber according to claim 1, is characterized in that: cooling adopts ring blowing to carry out, and wind-warm syndrome is 15 ~ 32 DEG C, and wind speed is 0.5 ~ 5.0m/s, and spinning speed is 800 ~ 1200m/min.

7. the preparation method of a kind of core-skin type regenerative polyester staple fiber according to claim 1, is characterized in that: the draw ratio of drawing-off is 1.2 ~ 3.5, drawing temperature 50 ~ 72 DEG C, and draft speed is 100 ~ 150m/min.

8. the regenerative polyester staple fiber that the preparation method according to claim 1 ~ 7 any one claim prepares.