Light weight heat-preserving fiber and preparation method thereof

Abstract

A lightweight heat-preserving fiber and a preparation method thereof are provided, wherein the fiber is prepared by measuring, composite spinneret's extruding, cooling, oiling, drawing, heat setting and winding a polyester melt. The composite spinneret has a hollow spinning hole and a circular spinning hole. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K ranges from 0.97 to 1.03. The oil agent contains a crown ether, and the content of the crown ether ranges from 67.30 to 85.58 wt %. The thermal conductivity of a knitted fabric having a basis weight of 100 g/m.sup.2 prepared by lightweight heat-preserving fiber is no larger than 0.150 W/m.Math.K.

Claims

1. A method for preparing a lightweight heat-preserving fiber, comprising: performing measuring, composite spinneret extrusion, cooling, oiling, drawing, heat setting, and winding on a polyester melt to obtain the lightweight heat-preserving fiber; wherein a composite spinneret plate has a plurality of hollow spinning holes and a plurality of circular spinning holes at the same time; a ratio of a micropore length of each hollow spinning hole of the plurality of hollow spinning holes to a micropore length of each hollow spinning hole of the plurality of circular spinning holes equals to a product of a ratio of an equivalent diameter of the each hollow spinning hole to an equivalent diameter of the each circular spinning hole and a coefficient K, the equivalent diameter of the each hollow spinning hole is a ratio of a cross-sectional area to a cross-sectional circumference of the each hollow spinning hole, the equivalent diameter of the each circular spinning hole is a ratio of a cross-sectional area to a cross-sectional circumference of the each circular spinning hole, and the coefficient K ranges from 0.97-1.03; wherein oiling involves using an oil agent contains a crown ether, and a content of the crown ether ranges from 67.30 wt %-85.58 wt %; wherein a bundle of the lightweight heat-preserving fiber extruded from the composite spinneret plate comprise a hollow monofilament and a circular monofilament, and the lightweight heat-preserving fiber is made of polyester; and wherein a thermal conductivity of a knitted fabric having a basis weight of 100 g/m.sup.2 is less than or equal to 0.150 W/m.Math.K, and the knitted fabric is prepared by the lightweight heat-preserving fiber.

2. The method of claim 1, wherein the micropore length of each hollow spinning hole and the micropore length of the each circular spinning hole range from 0.20 mm-1.28 mm; the equivalent diameter of the each hollow spinning hole and the equivalent diameter of the each circular spinning hole range from 0.10 mm-0.32 mm; and wherein the plurality of hollow spinning holes and the plurality of circular spinning holes are arranged concentrically on the composite spinneret plate; centers of the plurality of hollow spinning holes and centers of the plurality of circular spinning holes are on a first plurality of concentric circles; or centers of circumscribed circles of the plurality of hollow spinning holes and the plurality of circular spinning holes are on a second plurality of concentric circles; the first plurality of concentric circles and the second plurality of concentric circles are equidistant concentric circles; a first plurality of spinning holes of the plurality of hollow spinning holes and the plurality of circular spinning holes are arranged at a same interval, and the first plurality of spinning holes are on a same circle.

3. The method of claim 2, wherein the first plurality of spinning holes are hollow spinning holes or circular spinning holes, shapes of a second plurality of spinning holes of the plurality of hollow spinning holes and the plurality of circular spinning holes are different, and the second plurality of spinning holes are on adjacent two circles; or the first plurality of spinning holes comprise hollow spinning holes and circular spinning holes, a quantity ratio of the hollow spinning holes to the circular spinning holes in the first plurality of spinning holes ranges from 5-8:1.

4. The method of claim 1, wherein the oil agent has a thermal weight loss of less than 15% by weight after a heat treatment at 200° C. for 2 hours; wherein the oil agent has a kinematic viscosity of 27.5 mm.sup.2/s-30.1 mm.sup.2/s at (50±0.01) ° C., and the kinematic viscosity of the oil agent after being disposed in a concentration of 10 wt % is 0.93 mm.sup.2/s-0.95 mm.sup.2/s; wherein an oil film strength of the oil agent is 121 N-127 N; wherein a surface tension of the oil agent is 23.2 cN/cm-26.8 cN/cm, and a specific resistance of the oil agent is 1.0×10.sup.8-1.8×10.sup.8Ω.Math.cm; wherein after the oiling, a static friction coefficient between the lightweight heat-preserving fibers is 0.250-0.263, and a dynamic friction coefficient between the lightweight heat-preserving fibers is 0.262-0.273; and wherein after the oiling, a static friction coefficient between the lightweight heat-preserving fiber and a metal is 0.202-0.210, and a dynamic friction coefficient between the lightweight heat-preserving fiber and the metal is 0.320-0.332.

5. The method of claim 4, wherein the crown ether is 2-hydroxymethyl-12-crown-4, 15-crown-5, or 2-hydroxymethyl-15-crown-5; the oil agent further comprises a mineral oil, a potassium phosphate salt, a trimethylolpropane laurate and a sodium alkyl sulfonate; the mineral oil is one selected from the group consisting of mineral oils of 9 #-17 #; the potassium phosphate salt is a potassium salt of lauryl phosphate, an isomeric tridecyl polyoxyethylene ether phosphate potassium salt or a tetradecyl alcohol phosphate potassium salt; the sodium alkyl sulfonate is sodium dodecyl sulfate, sodium pentadecyl sulfonate or sodium hexadecane sulfonate; the oil agent in use is disposed in water to obtain an emulsion having a concentration of 10%-20% by weight; and a method for preparing the oil agent comprises: uniformly mixing the crown ether, the potassium phosphate salt, the trimethylolpropane laurate and the sodium alkyl sulfonate to obtain a first mixture; adding the first mixture to the mineral oil and stirring to obtain the oil agent; an amount of each of the mineral oil, the phosphate potassium salt, the trimethylolpropane laurate, the crown ether, and the sodium alkyl sulfonate by weight is as follows: mineral oil 0 part-10 parts; trimethylolpropane laurate 0 part-20 parts; crown ether 70 parts-100 parts; phosphate potassium salt 8 parts-15 parts; sodium alkyl sulfonate 2 parts-7 parts; the mixing is carried out at a normal temperature, and a temperature of the stirring is 40° C.-55° C., and a time of the stirring is 1 hour-3 hours.

6. The method of claim 1, wherein a plurality of spinning process parameters of a lightweight heat-preserving fiber POY yarn are as follows: spinning temperature: 280° C.-290° C.; cooling temperature: 20° C.-25° C.; winding speed: 2800 m/min-3200 m/min; a plurality of spinning process parameters of a lightweight heat-preserving fiber DTY yarn are as follows: spinning speed: 550 m/min-750 m/min; styling overfeed rate: 3.5%-5.5%; winding overfeed rate: 2.5%-5.0%; T1: 250° C.-265° C.; T2: 120° C.-135° C.; DR: 1.4-1.5; D/Y: 1.5-1.6; and network pressure: 0.05 MPa-0.3 MPa.

7. The method of claim 1, wherein a fineness of the hollow monofilament is 1.5 dtex-2.5 dtex, and a fineness of the circular monofilament is 0.20 dtex-0.30 dtex.

8. The method of claim 1, wherein a fineness of the lightweight heat-preserving fiber is 75 dtex-100 dtex, a breaking strength of the lightweight heat-preserving fiber is larger than or equal to 2.1 cN/dtex, and an elongation at break of the lightweight heat-preserving fiber is 20.0±2.0%, a crimp shrinkage of the lightweight heat-preserving fiber is less than or equal to 9.0%, a linear density deviation of the lightweight heat-preserving fiber is less than or equal to 2.0%, a breaking strength coefficient of variation (CV) value of the lightweight heat-preserving fiber is less than or equal to 7.0%, an elongation at break CV value of the lightweight heat-preserving fiber is less than or equal to 8.0%, a crimp shrinkage CV value of the lightweight heat-preserving fiber is less than or equal to 8.5%, and a boiling water shrinkage of the lightweight heat-preserving fiber is 3.5±0.5%.

9. The method of claim 8, wherein the lightweight heat-preserving fiber has a capillary parameter of greater than or equal to 0.10.

10. The method of claim 2, wherein a plurality of spinning process parameters of a lightweight heat-preserving fiber POY yarn are as follows: spinning temperature: 280° C.-290° C.; cooling temperature: 20° C.-25° C.; winding speed: 2800 m/min-3200 m/min; a plurality of spinning process parameters of a lightweight heat-preserving fiber DTY yarn are as follows: spinning speed: 550 m/min-750 m/min; styling overfeed rate: 3.5%-5.5%; winding overfeed rate: 2.5%-5.0%; T1: 250° C.-265° C.; T2: 120° C.-135° C.; DR: 1.4-1.5; D/Y: 1.5-1.6; network pressure: 0.05 MPa-0.3 MPa.

11. The method of claim 3, wherein a plurality of spinning process parameters of a lightweight heat-preserving fiber POY yarn are as follows: spinning temperature: 280° C.-290° C.; cooling temperature: 20° C.-25° C.; winding speed: 2800 m/min-3200 m/min; a plurality of spinning process parameters of a lightweight heat-preserving fiber DTY yarn are as follows: spinning speed: 550 m/min-750 m/min; styling overfeed rate: 3.5%-5.5%; winding overfeed rate: 2.5%-5.0%; T1: 250° C.-265° C.; T2: 120° C.-135° C.; DR: 1.4-1.5; D/Y: 1.5-1.6; network pressure: 0.05 MPa-0.3 MPa.

12. The method of claim 4, wherein a plurality of spinning process parameters of a lightweight heat-preserving fiber POY yarn are as follows: spinning temperature: 280° C.-290° C.; cooling temperature: 20° C.-25° C.; winding speed: 2800 m/min-3200 m/min; a plurality of spinning process parameters of a lightweight heat-preserving fiber DTY yarn are as follows: spinning speed: 550 m/min-750 m/min; styling overfeed rate: 3.5%-5.5%; winding overfeed rate: 2.5%-5.0%; T1: 250° C.-265° C.; T2: 120° C.-135° C.; DR: 1.4-1.5; D/Y: 1.5-1.6; network pressure: 0.05 MPa-0.3 MPa.

13. The method of claim 5, wherein a plurality of spinning process parameters of a lightweight heat-preserving fiber POY yarn are as follows: spinning temperature: 280° C.-290° C.; cooling temperature: 20° C.-25° C.; winding speed: 2800 m/min-3200 m/min; a plurality of spinning process parameters of a lightweight heat-preserving fiber DTY yarn are as follows: spinning speed: 550 m/min-750 m/min; styling overfeed rate: 3.5%-5.5%; winding overfeed rate: 2.5%-5.0%; T1: 250° C.-265° C.; T2: 120° C.-135° C.; DR: 1.4-1.5; D/Y: 1.5-1.6; network pressure: 0.05 MPa-0.3 MPa.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGURE is a schematic view of the arrangement of the spinning holes of the composite spinneret in Example 1 of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) Hereinafter, the present invention will be described in more detail by the following examples. It should be noticed that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. In addition, it should be noticed that after reading the content of the present invention, those skilled in this field can make various modifications or changes to the present invention, and these equivalent forms also apply to the scope of the appended claims of this application.

Example 1

(3) A lightweight heat-preserving fiber, its preparation method comprises:

(4) (1) the preparation of oil agent in oiling;

(5) Uniformly mix 2-hydroxymethyl-12-crown-4 with dodecyl phosphate potassium salt, trimethylolpropane laurate and sodium hexadecane sulfonate at room temperature and put into 12 # mineral oil. Then uniformly stir at 40° C. for 2.5 hours to obtain an oil agent. By weight, the components are added with the following amounts: 12 # mineral oil 5 parts; 2-hydroxymethyl-12-crown-4 95 parts; dodecyl phosphate potassium salt 9 parts; sodium hexadecyl sulfonate 2 parts. The content of crown ether in the prepared oil agent is 85.58 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 9 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 29.5 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.93 mm.sup.2/s, the oil film strength of the oil is 121 N, and the surface tension of the oil is 24.3 cN/cm. The specific resistance is 1.0×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.260, and the coefficient of dynamic friction (μ.sub.d) is 0.263. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.202, the coefficient of dynamic friction (μ.sub.d) is 0.330, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 19% by weight;

(6) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(7) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time, and a schematic arrangement diagram of the spinning hole is shown in FIGURE, wherein A represents a hollow spinning hole, and B represents a circular spinning hole. The ratio of the micropore length of A to B is equal to the ratio of the equivalent diameter of A to B multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 1.01, the micro-hole length of the hollow spinning hole is 0.38 mm, and the micro-hole length of the circular spinning hole is 0.38 mm. The equivalent diameter is 0.18 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals, and the spinning holes on the same circle are hollow spinning holes or circular spinning holes, and the shapes of the spinning holes on the adjacent two circles are different. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 280° C.; the cooling temperature is 21° C.; the winding speed is 3200 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 600 m/min; setting overfeed rate is 4.5%; winding overfeed rate is 3.0%; T1 is 258° C.; T2 is 127° C.; DR is 1.4; D/Y is 1.6; network pressure is 0.25 MPa.

(8) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.10. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.148 W/m.Math.K, the hollow monofilament has a fineness of 1.8 dtex, and the circular monofilament has a fineness of 0.30 dtex. The lightweight thermal fiber has a fineness of 100 dtex, a breaking strength of 2.2 cN/dtex, an elongation at break of 18.0%, a crimp shrinkage of 8.3%, a linear density deviation of 1.3%, and a breaking strength CV of 6.4%, the elongation at break CV value of 7.5%, the variation coefficient CV of the crimp shrinkage rate of 8.2%, and the boiling water shrinkage of 3.5%.

Example 2

(9) A lightweight heat-preserving fiber, its preparation method comprises:

(10) (1) the preparation of oil agent in oiling;

(11) Uniformly mix 15-crown-5 and isomeric tridecyl ethoxylate phosphate potassium salt, trimethylolpropane laurate and sodium dodecyl sulfate at room temperature and put into 13 # mineral oil. Then uniformly stir at 52° C. for 2 hours to obtain an oil agent. By weight, the components are added with the following amounts: 13 # mineral oil 10 parts; trimethylolpropane laurate 5 parts; 15-crown-5 70 parts; isomeric tridecyl ethoxylate phosphate potassium salt 8 parts, sodium dodecyl sulfate 6 parts. The content of crown ether in the prepared oil agent is 70.70 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 13.5 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 28.6 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.95 mm.sup.2/s, the oil film strength of the oil is 126 N, and the surface tension of the oil is 24.9 cN/cm. The specific resistance is 1.2×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.251, and the coefficient of dynamic friction (μ.sub.d) is 0.262. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.202, the coefficient of dynamic friction (μ.sub.d) is 0.332, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 11% by weight;

(12) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(13) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 0.99, the micro-hole length of the hollow spinning hole is 0.59 mm, and the micro-hole length of the circular spinning hole is 0.59 mm. The equivalent diameter is 0.10 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals, and there are hollow spinning holes and circular spinning holes on the same circle. The quantity ratio of hollow spinning holes to the circular spinning holes is 5:1. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 286° C.; the cooling temperature is 22° C.; the winding speed is 2800 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 700 m/min; setting overfeed rate is 4.0%; winding overfeed rate is 4.5%; T1 is 256° C.; T2 is 129° C.; DR is 1.5; D/Y is 1.6; network pressure is 0.3 MPa.

(14) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.18. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.147 W/m.Math.K, the hollow monofilament has a fineness of 2.3 dtex, and the circular monofilament has a fineness of 0.28 dtex. The lightweight thermal fiber has a fineness of 75 dtex, a breaking strength of 3.0 cN/dtex, an elongation at break of 20.0%, a crimp shrinkage of 8.2%, a linear density deviation of 1.5%, and a breaking strength CV of 6.2%, the elongation at break CV value of 7.9%, the variation coefficient CV of the crimp shrinkage rate of 8.4%, and the boiling water shrinkage of 3.0%.

Example 3

(15) A lightweight heat-preserving fiber, its preparation method comprises:

(16) (1) the preparation of oil agent in oiling;

(17) Uniformly mix 2-hydroxymethyl-15-crown-5 and dodecacanol phosphate potassium salt, trimethylolpropane laurate and sodium pentadecyl sulfonate at room temperature and put into 11 # mineral oil. Then uniformly stir at 48° C. for 3 hours to obtain an oil agent. By weight, the components are added with the following amounts: 11 # mineral oil 8 parts; trimethylolpropane laurate 10 parts; 2-hydroxymethyl-15-crown-5 85 parts; dodecacanol phosphate potassium salt 11 parts, sodium pentadecyl sulfonate 5 parts. The content of crown ether in the prepared oil agent is 70.83 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 11 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 30.1 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.94 mm.sup.2/s, the oil film strength of the oil is 125 N, and the surface tension of the oil is 23.2 cN/cm. The specific resistance is 1.8×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.250, and the coefficient of dynamic friction (μ.sub.d) is 0.272. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.209, the coefficient of dynamic friction (μ.sub.d) is 0.329, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 10% by weight;

(18) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(19) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 1.00, the micro-hole length of the hollow spinning hole is 0.20 mm, and the micro-hole length of the circular spinning hole is 0.20 mm. The equivalent diameter is 0.16 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals, and there are hollow spinning holes and circular spinning holes on the same circle. The quantity ratio of hollow spinning holes to the circular spinning holes is 6:1. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 285° C.; the cooling temperature is 25° C.; the winding speed is 2900 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 550 m/min; setting overfeed rate is 3.5%; winding overfeed rate is 2.5%; T1 is 250° C.; T2 is 122° C.; DR is 1.5; D/Y is 1.55; network pressure is 0.15 MPa.

(20) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.18. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.150 W/m.Math.K, the hollow monofilament has a fineness of 1.6 dtex, and the circular monofilament has a fineness of 0.21 dtex. The lightweight thermal fiber has a fineness of 85 dtex, a breaking strength of 2.5 cN/dtex, an elongation at break of 18.0%, a crimp shrinkage of 8.9%, a linear density deviation of 1.8%, and a breaking strength CV of 6.6%, the elongation at break CV value of 7.5%, the variation coefficient CV of the crimp shrinkage rate of 8.1%, the boiling water shrinkage of 3.0%, and the capillary parameter of 0.19.

Example 4

(21) A lightweight heat-preserving fiber, its preparation method comprises:

(22) (1) the preparation of oil agent in oiling;

(23) Uniformly mix 2-hydroxymethyl-12-crown-4 with dodecyl phosphate potassium salt, trimethylolpropane laurate and sodium hexadecane sulfonate at room temperature and put into 12 # mineral oil. Then uniformly stir at 40° C. for 2.5 hours to obtain an oil agent. By weight, the components are added with the following amounts: 12 # mineral oil 5 parts; 2-hydroxymethyl-12-crown-4 95 parts; dodecyl phosphate potassium salt 9 parts; sodium hexadecyl sulfonate 2 parts. The content of crown ether in the prepared oil agent is 85.58 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 9 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 29.5 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.93 mm.sup.2/s, the oil film strength of the oil is 121 N, and the surface tension of the oil is 24.3 cN/cm. The specific resistance is 1.0×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.260, and the coefficient of dynamic friction (μ.sub.d) is 0.263. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.202, the coefficient of dynamic friction (μ.sub.d) is 0.330, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 19% by weight;

(24) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(25) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 1.02, the micro-hole length of the hollow spinning hole is 0.97 mm, and the micro-hole length of the circular spinning hole is 0.97 mm. The equivalent diameter is 0.24 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals, and there are hollow spinning holes and circular spinning holes on the same circle. The quantity ratio of hollow spinning holes to the circular spinning holes is 7:1. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 288° C.; the cooling temperature is 25° C.; the winding speed is 3200 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 650 m/min; setting overfeed rate is 5.5%; winding overfeed rate is 4.0%; T1 is 262° C.; T2 is 135° C.; DR is 1.43; D/Y is 1.5; network pressure is 0.20 MPa.

(26) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.10. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.144 W/m.Math.K, the hollow monofilament has a fineness of 1.5 dtex, and the circular monofilament has a fineness of 0.24 dtex. The lightweight thermal fiber has a fineness of 85 dtex, a breaking strength of 2.8 cN/dtex, an elongation at break of 20.0%, a crimp shrinkage of 8.0%, a linear density deviation of 0.5%, and a breaking strength CV of 5.9%, the elongation at break CV value of 8.0%, the variation coefficient CV of the crimp shrinkage rate of 7.9%, and the boiling water shrinkage of 4.0%.

Example 5

(27) A lightweight heat-preserving fiber, its preparation method comprises:

(28) (1) the preparation of oil agent in oiling;

(29) Uniformly mix 15-crown-5 and isomeric tridecyl ethoxylate phosphate potassium salt, trimethylolpropane laurate and sodium dodecyl sulfate at room temperature and put into 13 # mineral oil. Then uniformly stir at 52° C. for 2 hours to obtain an oil agent. By weight, the components are added with the following amounts: 13 # mineral oil 10 parts; trimethylolpropane laurate 5 parts; 15-crown-5 70 parts; isomeric tridecyl ethoxylate phosphate potassium salt 8 parts, sodium dodecyl sulfate 6 parts. The content of crown ether in the prepared oil agent is 70.70 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 13.5 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 28.6 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.95 mm.sup.2/s, the oil film strength of the oil is 126 N, and the surface tension of the oil is 24.9 cN/cm. The specific resistance is 1.2×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.251, and the coefficient of dynamic friction (μ.sub.d) is 0.262. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.202, the coefficient of dynamic friction (μ.sub.d) is 0.332, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 11% by weight;

(30) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(31) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 0.97, the micro-hole length of the hollow spinning hole is 1.05 mm, and the micro-hole length of the circular spinning hole is 1.05 mm. The equivalent diameter is 0.16 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals, and there are hollow spinning holes and circular spinning holes on the same circle. The quantity ratio of hollow spinning holes to the circular spinning holes is 8:1. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 290° C.; the cooling temperature is 20° C.; the winding speed is 3000 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 750 m/min; setting overfeed rate is 5.5%; winding overfeed rate is 5.0%; T1 is 260° C.; T2 is 131° C.; DR is 1.49; D/Y is 1.52; network pressure is 0.25 MPa.

(32) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.12. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.150 W/m.Math.K, the hollow monofilament has a fineness of 1.8 dtex, and the circular monofilament has a fineness of 0.22 dtex. The lightweight thermal fiber has a fineness of 95 dtex, a breaking strength of 2.4 cN/dtex, an elongation at break of 22.0%, a crimp shrinkage of 8.4%, a linear density deviation of 1.6%, and a breaking strength CV of 7.0%, the elongation at break CV value of 7.6%, the variation coefficient CV of the crimp shrinkage rate of 8.0%, and the boiling water shrinkage of 3.5%.

Example 6

(33) A lightweight heat-preserving fiber, its preparation method comprises:

(34) (1) the preparation of oil agent in oiling;

(35) Uniformly mix 2-hydroxymethyl-15-crown-5 and twelve-tetradecyl phosphate potassium salt, trimethylolpropane laurate and sodium pentadecyl sulfonate at room temperature and put into 14 # mineral oil. Then uniformly stir at 55° C. for 1 hours to obtain an oil agent. By weight, the components are added with the following amounts: 14 # mineral oil 3 parts; trimethylolpropane laurate 10 parts; 2-hydroxymethyl-15-crown-5 75 parts; twelve-tetradecyl phosphate potassium salt 14 parts, sodium pentadecyl sulfonate 7 parts. The content of crown ether in the prepared oil agent is 68.80 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 12 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 27.5 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.95 mm.sup.2/s, the oil film strength of the oil is 126 N, and the surface tension of the oil is 25.4 cN/cm. The specific resistance is 1.6×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.255, and the coefficient of dynamic friction (μ.sub.d) is 0.267. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.203, the coefficient of dynamic friction (μ.sub.d) is 0.330, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 20% by weight;

(36) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(37) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 0.99, the micro-hole length of the hollow spinning hole is 0.72 mm, and the micro-hole length of the circular spinning hole is 0.725 mm. The equivalent diameter is 0.32 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals, and there are hollow spinning holes and circular spinning holes on the same circle. The quantity ratio of hollow spinning holes to the circular spinning holes is 8:1. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 280° C.; the cooling temperature is 22° C.; the winding speed is 3100 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 550 m/min; setting overfeed rate is 5.5%; winding overfeed rate is 4.5%; T1 is 265° C.; T2 is 120° C.; DR is 1.45; D/Y is 1.58; network pressure is 0.05 MPa.

(38) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.18. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.142 W/m.Math.K, the hollow monofilament has a fineness of 2.5 dtex, and the circular monofilament has a fineness of 0.20 dtex. The lightweight thermal fiber has a fineness of 100 dtex, a breaking strength of 2.1 cN/dtex, an elongation at break of 22.0%, a crimp shrinkage of 9.0%, a linear density deviation of 2.0%, and a breaking strength CV of 6.5%, the elongation at break CV value of 7.1%, the variation coefficient CV of the crimp shrinkage rate of 8.2%, and the boiling water shrinkage of 4.0%.

Example 7

(39) A lightweight heat-preserving fiber, its preparation method comprises:

(40) (1) the preparation of oil agent in oiling;

(41) Uniformly mix 15-crown-5 and dodecyl phosphate potassium salt, trimethylolpropane laurate and sodium hexadecyl sulfonate at room temperature and put into 15 # mineral oil. Then uniformly stir at 41° C. for 2 hours to obtain an oil agent. By weight, the components are added with the following amounts: 15 # mineral oil 8 parts; trimethylolpropane laurate 20 parts; 15-crown-5 100 parts; dodecyl phosphate potassium salt 15 parts, sodium hexadecyl sulfonate 2 parts. The content of crown ether in the prepared oil agent is 68.97 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 8.5 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 28.4 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.94 mm.sup.2/s, the oil film strength of the oil is 122 N, and the surface tension of the oil is 26.8 cN/cm. The specific resistance is 1.8×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.263, and the coefficient of dynamic friction (μ.sub.d) is 0.268. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.210, the coefficient of dynamic friction (μ.sub.d) is 0.320, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 13% by weight;

(42) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(43) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 0.98, the micro-hole length of the hollow spinning hole is 1.28 mm, and the micro-hole length of the circular spinning hole is 1.287 mm. The equivalent diameter is 0.17 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals. The spinning holes on the neighbouring circles are different. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 283° C.; the cooling temperature is 23° C.; the winding speed is 2900 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 550 m/min; setting overfeed rate is 5.0%; winding overfeed rate is 2.5%; T1 is 255° C.; T2 is 135° C.; DR is 1.5; D/Y is 1.56; network pressure is 0.05 MPa.

(44) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.20. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.140 W/m.Math.K, the hollow monofilament has a fineness of 2.3 dtex, and the circular monofilament has a fineness of 0.25 dtex. The lightweight thermal fiber has a fineness of 95 dtex, a breaking strength of 3.6 cN/dtex, an elongation at break of 18.0%, a crimp shrinkage of 8.2%, a linear density deviation of 1.4%, and a breaking strength CV of 6.0%, the elongation at break CV value of 7.2%, the variation coefficient CV of the crimp shrinkage rate of 7.4%, and the boiling water shrinkage of 3.5%.

Example 8

(45) A lightweight heat-preserving fiber, its preparation method comprises:

(46) (1) the preparation of oil agent in oiling;

(47) Uniformly mix 2-hydroxymethyl-12-crown-4 and twelve-tetradecyl phosphate potassium salt, trimethylolpropane laurate and sodium pentadecyl sulfonate at room temperature and put into 16 # mineral oil. Then uniformly stir at 45° C. for 3 hours to obtain an oil agent. By weight, the components are added with the following amounts: 16 # mineral oil 9 parts; 2-hydroxymethyl-12-crown-4 80 parts; twelve-tetradecyl phosphate potassium salt 12 parts; sodium pentadecyl sulfonate 5 parts. The content of crown ether in the prepared oil agent is 83.33 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 14 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 30.0 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.93 mm.sup.2/s, the oil film strength of the oil is 127 N, and the surface tension of the oil is 23.5 cN/cm. The specific resistance is 1.5×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.262, and the coefficient of dynamic friction (μ.sub.d) is 0.273. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.208, the coefficient of dynamic friction (μ.sub.d) is 0.328, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 18% by weight;

(48) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(49) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 1.03, the micro-hole length of the hollow spinning hole is 0.54 mm, and the micro-hole length of the circular spinning hole is 0.54 mm. The equivalent diameter is 0.16 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals. The spinning holes on the neighbouring circles are different. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 280° C.; the cooling temperature is 23° C.; the winding speed is 3200 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 550 m/min; setting overfeed rate is 4.5%; winding overfeed rate is 3.5%; T1 is 250° C.; T2 is 125° C.; DR is 1.5; D/Y is 1.6; network pressure is 0.1 MPa.

(50) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.16. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.150 W/m.Math.K, the hollow monofilament has a fineness of 2.2 dtex, and the circular monofilament has a fineness of 0.25 dtex. The lightweight thermal fiber has a fineness of 79 dtex, a breaking strength of 2.8 cN/dtex, an elongation at break of 20.0%, a crimp shrinkage of 8.7%, a linear density deviation of 2.0%, and a breaking strength CV of 6.4%, the elongation at break CV value of 8.0%, the variation coefficient CV of the crimp shrinkage rate of 7.0%, and the boiling water shrinkage of 3.0%.

Example 9

(51) A lightweight heat-preserving fiber, its preparation method comprises:

(52) (1) the preparation of oil agent in oiling;

(53) Uniformly mix 2-hydroxymethyl-15-crown-5 and dodecyl phosphate potassium salt, trimethylolpropane laurate and sodium dodecyl sulfate at room temperature. Then uniformly stir at 55° C. for 3 hours to obtain an oil agent. By weight, the components are added with the following amounts: trimethylolpropane laurate 15 parts; 2-hydroxymethyl-15-crown-5 90 parts; dodecyl phosphate potassium salt 8 parts; sodium dodecyl sulfate 7 parts. The content of crown ether in the prepared oil agent is 81.81 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 10 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 29.7 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.94 mm.sup.2/s, the oil film strength of the oil is 126 N, and the surface tension of the oil is 24.8 cN/cm. The specific resistance is 1.8×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.250, and the coefficient of dynamic friction (μ.sub.d) is 0.264. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.210, the coefficient of dynamic friction (μ.sub.d) is 0.321, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 10% by weight;

(54) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(55) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 0.97, the micro-hole length of the hollow spinning hole is 0.49 mm, and the micro-hole length of the circular spinning hole is 0.49 mm. The equivalent diameter is 0.12 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals, and there are hollow spinning holes and circular spinning holes on the same circle. The quantity ratio of hollow spinning holes to the circular spinning holes is 5:1. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 287° C.; the cooling temperature is 24° C.; the winding speed is 2800 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 550 m/min; setting overfeed rate is 4.0%; winding overfeed rate is 3.5%; T1 is 263° C.; T2 is 120° C.; DR is 1.42; D/Y is 1.54; network pressure is 0.05 MPa.

(56) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.19. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.149 W/m.Math.K, the hollow monofilament has a fineness of 1.5 dtex, and the circular monofilament has a fineness of 0.24 dtex. The lightweight thermal fiber has a fineness of 80 dtex, a breaking strength of 2.5 cN/dtex, an elongation at break of 18.0%, a crimp shrinkage of 8.2%, a linear density deviation of 0.9%, and a breaking strength CV of 6.7%, the elongation at break CV value of 7.4%, the variation coefficient CV of the crimp shrinkage rate of 8.5%, and the boiling water shrinkage of 3.0%.

Example 10

(57) A lightweight heat-preserving fiber, its preparation method comprises:

(58) (1) the preparation of oil agent in oiling;

(59) Uniformly mix 2-hydroxymethyl-15-crown-5 and dodecyl phosphate potassium salt, trimethylolpropane laurate and sodium dodecyl sulfate at room temperature. Then uniformly stir at 55° C. for 3 hours to obtain an oil agent. By weight, the components are added with the following amounts: trimethylolpropane laurate 15 parts; 2-hydroxymethyl-15-crown-5 90 parts; dodecyl phosphate potassium salt 8 parts; sodium dodecyl sulfate 7 parts. The content of crown ether in the prepared oil agent is 81.81 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 10 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 29.7 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.94 mm.sup.2/s, the oil film strength of the oil is 126 N, and the surface tension of the oil is 24.8 cN/cm. The specific resistance is 1.8×10.sup.8Ω.Math.cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.250, and the coefficient of dynamic friction (μ.sub.d) is 0.264. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.210, the coefficient of dynamic friction (μ.sub.d) is 0.321, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 10% by weight;

(60) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(61) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 0.98, the micro-hole length of the hollow spinning hole is 0.24 mm, and the micro-hole length of the circular spinning hole is 0.24 mm. The equivalent diameter is 0.25 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals, and there are hollow spinning holes and circular spinning holes on the same circle. The quantity ratio of hollow spinning holes to the circular spinning holes is 7:1. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 283° C.; the cooling temperature is 25° C.; the winding speed is 2900 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 750 m/min; setting overfeed rate is 3.5%; winding overfeed rate is 4.0%; T1 is 259° C.; T2 is 130° C.; DR is 1.4; D/Y is 1.51; network pressure is 0.3 MPa.

(62) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.12. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.143 W/m.Math.K, the hollow monofilament has a fineness of 1.9 dtex, and the circular monofilament has a fineness of 0.23 dtex. The lightweight thermal fiber has a fineness of 85 dtex, a breaking strength of 2.1 cN/dtex, an elongation at break of 22.0%, a crimp shrinkage of 9.0%, a linear density deviation of 1.7%, and a breaking strength CV of 6.8%, the elongation at break CV value of 7.9%, the variation coefficient CV of the crimp shrinkage rate of 8.3%, and the boiling water shrinkage of 3.5%.

Example 11

(63) A lightweight heat-preserving fiber, its preparation method comprises:

(64) (1) the preparation of oil agent in oiling;

(65) Uniformly mix 2-hydroxymethyl-12-crown-4 with dodecyl phosphate potassium salt, trimethylolpropane laurate and sodium dodecyl sulfate at room temperature and put into 9 # mineral oil. Then uniformly stir at 40° C. for 1 hours to obtain an oil agent. By weight, the components are added with the following amounts: 9 # mineral oil 2 parts; 2-hydroxymethyl-12-crown-4 90 parts; dodecyl phosphate potassium salt 8 parts; sodium dodecyl sulfate 3 parts, trimethylolpropane laurate 10 parts. The content of crown ether in the prepared oil agent is 79.6 wt %, and the oil agent has excellent high temperature resistance. After heat treatment at 200° C. for 2 hours, the weight loss of oil agent is 14.5 wt %, and the viscosity of the oil agent is relatively low, at (50±0.01) ° C. the kinematic viscosity is 29.6 mm.sup.2/s, the kinematic viscosity with 10 wt % concentration after being dissolved by water is 0.93 mm.sup.2/s, the oil film strength of the oil is 125 N, and the surface tension of the oil is 24.8 cN/cm. The specific resistance is 1.3×10.sup.8Ω˜cm. After oiling, the coefficient of static friction (μ.sub.s) between fiber and fiber (F/F) is 0.255, and the coefficient of dynamic friction (μ.sub.d) is 0.266. After oiling, fiber and metal (F/M) The coefficient of static friction (μ.sub.s) is 0.203, the coefficient of dynamic friction (μ.sub.d) is 0.320, and the oil agent is prepared by adding water to obtain an emulsion having a concentration of 15% by weight;

(66) (2) The lightweight heat-preserving fiber obtained by subjecting the polyester melt to measuring, extrusion by composite spinneret, cooling, oiling, drawing, heat setting and winding.

(67) The composite spinneret plate has a hollow spinning hole and a circular spinning hole at the same time. The ratio of the micropore length of hollow spinning hole to circular spinning hole equals to the ratio of the equivalent diameter of hollow spinning hole to circular spinning hole multiplies the coefficient K, and the equivalent diameter is the ratio of the cross-sectional area to the circumference of the cross-section, the coefficient K is 1.03, the micro-hole length of the hollow spinning hole is 0.60 mm, and the micro-hole length of the circular spinning hole is 0.598 mm. The equivalent diameter is 0.27 mm, and all the spinning holes are arranged concentrically on the spinneret. The centers of all the spinning holes or the center of the circumscribed circle are on the concentric circles. The concentric circles are equidistant concentric circles on the same circle. The spinning holes on the same circle are arranged at equal intervals, and there are hollow spinning holes and circular spinning holes on the same circle. The quantity ratio of hollow spinning holes to the circular spinning holes is 7:1. The spinning process parameters of the lightweight heat-preserving fiber POY yarn are as follows: the spinning temperature is 290° C.; the cooling temperature is 20° C.; the winding speed is 3100 m/min; the spinning process parameters of the lightweight heat-preserving fiber DTY yarn are as follows: the spinning speed is 700 m/min; setting overfeed rate is 4.5%; winding overfeed rate is 5.0%; T1 is 261° C.; T2 is 134° C.; DR is 1.5; D/Y is 1.5; network pressure is 0.20 MPa.

(68) The final obtained spinneret can extrude a bundle of lightweight heat-preserving fiber containing both hollow monofilament and round monofilament having a capillary parameter of 0.13. The knit fabric having a basis weight of 100 g/m.sup.2 prepared from lightweight heat-preserving fibers has a thermal conductivity of 0.144 W/m.Math.K, the hollow monofilament has a fineness of 2.5 dtex, and the circular monofilament has a fineness of 0.20 dtex. The lightweight thermal fiber has a fineness of 100 dtex, a breaking strength of 2.3 cN/dtex, an elongation at break of 18.0%, a crimp shrinkage of 8.5%, a linear density deviation of 1.4%, and a breaking strength CV of 6.6%, the elongation at break CV value of 7.5%, the variation coefficient CV of the crimp shrinkage rate of 7.6%, and the boiling water shrinkage of 4.0%.