KR101772586B1 - A polypropylene fiber with high tenacity and low shrinkage and its manufacturing process - Google Patents

Abstract

Melt-spinning a polypropylene resin having a melt index of 5 to 12 and cooling and solidifying to form an undrawn yarn; And a step of subjecting the undrawn yarn to a stretching-heat fixing-relaxation-winding-stretching process using a multi-stage stretching roller, and a high-strength, low-shrinking polypropylene fiber is proposed .

Description

TECHNICAL FIELD [0001] The present invention relates to a high-strength low-shrinkage polypropylene fiber and a manufacturing method thereof,

The present invention relates to a polypropylene fiber having a high heat shrinkage property while maintaining a high strength higher than that of conventional industrial polypropylene yarns and a method for producing the same. More specifically, the present invention relates to a polypropylene fiber Low shrinkage polypropylene fibers manufactured by optimizing spinning conditions and winding conditions so as to produce industrial polypropylene yarns having a low heat shrinkage characteristic while maintaining high strength properties, and a method for producing the same.

In general, polypropylene fibers are widely used as industrial fibers because of their excellent physical and chemical properties such as strength, chemical resistance and light weight, but there is a continuing increase in the demand for yarns having a lower heat shrinkage ratio required in the post- In fact. The polypropylene fibers used in the present market are not suitable for development for textile coatings that are required to have low heat shrinkage characteristics because they are designed to be suitable for ropes and civil engineering purposes. The quality of wrinkles caused by high heat shrinkage on the surface of final coating product A problem arises.

The method of producing high strength low shrinkage yarn can be considered in various directions. In the resin level, it is possible to consider a method of modifying the resin itself or modifying the direction of using the additive and changing the radiating device or equipment. Additional investment costs are incurred, which reduces the economic benefits that can be gained in achieving the technology. Therefore, in the present invention, it is desired to optimize the melt index of the resin and to optimize the production conditions (spinning and winding conditions) to exhibit high strength and low shrinkage characteristics superior to conventional industrial yarns while maintaining excellent processability.

Some of the technologies that have already been released include:

Korean Patent Publication No. 2009-0060098 discloses a method for producing a high strength polypropylene of 1 GPa or more using a gel spinning method. However, there is a problem of low productivity due to a solvent recovery problem due to wet spinning and a two-step manufacturing method.

Korean Patent Publication No. 2003-0097877 discloses a method of producing a low shrinkage polypropylene fiber by using a nucleating agent compound. However, a separate facility for adding additives is required, and the stretching magnification is 3.5 times so that the strength stays at 4 g / d. Korean Patent No. 2013-0001770 discloses a method of producing a high strength polypropylene fiber of 7.5 g / d or more by using a diether catalyst and an organic stiff nucleating agent. However, the heat shrinkage of the fabric is 10% or more, Inappropriate. In Korean Patent No. 2000-0041155, high-strength polypropylene fibers having a strength of 7.0 g / d and U 2.0% are produced. However, since they are produced without cold rolling and relaxation, they exhibit high strength. Therefore, in a coating process requiring high temperature heat treatment, The strength of the final product due to the development is lowered and the problem of shrinkage non-uniformity is accompanied.

An object of the present invention is to solve the problems and disadvantages of the prior art mentioned above by selecting appropriate resins without using equipment modification, resin modification or additives, and then optimizing spinning conditions and winding conditions, It is an object of the present invention to provide a method for manufacturing a high-strength polypropylene fiber by winding it at a high speed while having low shrinkage characteristics superior to polypropylene fibers.

To solve these problems, according to one aspect of the present invention,

Melt-spinning a polypropylene resin having a melt index of 5 to 12 and cooling and solidifying to form an undrawn yarn; And

There is provided a process for producing a high strength, low shrinkage polypropylene fiber comprising a step of subjecting the undrawn yarn to a stretching-heat fixing-relaxation-winding-stretching process using a multi-stage stretching roller.

The cylinder temperature of the extruder for melt-spinning the polypropylene resin in the step of forming the non-drawn filament may be adjusted to 170 to 200 캜.

Wherein the stretching step is carried out at a stretching ratio of 5.5 to 6.0 and the relaxation step is carried out at a relaxation rate of 8 to 12% and a relaxation zone temperature of 150 to 160 DEG C and the winding step is carried out at a winding speed of 2,500 m / min or more have.

According to another aspect of the present invention,

A high strength, low shrinkage polypropylene fiber produced by the process described above is provided.

The polypropylene fiber may have an intensity of 7.0 g / d or more and a shrinkage of 5% or less.

According to one embodiment of the present invention, it is possible to provide a method for producing polypropylene fibers having a higher level of strength and a lower level of shrinkage than conventional high strength industrial polypropylene by high speed winding, and more specifically, It is possible to determine the melt index of the polypropylene resin suitable for exhibiting good processability and at the same time to optimize the spinning conditions and the winding conditions to produce a yarn exhibiting a higher shrinkage ratio and a higher strength than that of conventional industrial polypropylene fibers .

The polypropylene fiber thus produced can be effectively utilized as a material for a wide range of industrial textile fields such as tarpaulins, truck cover sheets, billboards, and leisure goods, which are required to be lightweight and recyclable.

Fig. 1 is a schematic view of a polypropylene fiber production apparatus used in the production method of the present invention.

Hereinafter, the method for producing a polypropylene fiber of the present invention will be described in detail. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately Should be construed in accordance with the principles of the present invention,

The present invention relates to a process for producing a high-strength, low-shrinkage polypropylene fiber excellent in workability without modification of equipment or modification of a polymer, or an additive, wherein a resin melt index at an appropriate level capable of exhibiting high- The chip is melt-spun and the cooled and solidified polypropylene undrawn yarn filament yarn is subjected to a radial emulsion (Kiss Roller or Jet Oiler) using a conventional radial emulsion applying device before a high-defect roller, and then a multi- Followed by stretching, heat fixing, relaxation, and winding.

The present invention relates to a polypropylene resin which is suitable for exhibiting physical properties and good processability and which has a melt index which is higher than that of a conventional industrial polypropylene fiber and has a low shrinkage ratio Is produced at a high speed.

The present invention is characterized in that a polypropylene chip having a melt index of 5 to 12 is melted and melt-spinned at an extruder cylinder temperature of 170 to 200 占 폚, followed by emulsion application, multi-stage stretching, heat fixing and relaxation.

Further, in the present invention, in order to produce a yarn satisfying both the high strength of not less than 7.0 g / d and the low shrinkage of not more than 5% of the conventional industrial polypropylene yarn, the polypropylene undrawn yarn is stretched in a multi- 6.0, a relaxation rate of 8% to 12%, a relaxation zone temperature of 150 to 160 ° C, and a winding speed of 2,500 m / min or more.

The present invention achieves a method capable of producing a polypropylene fiber having a high workability and high strength and low shrinkage property at a winding speed of 2,500 m / min or more by a direct radiation drawing process.

Hereinafter, the present invention will be described in detail.

According to one embodiment of the present invention, the polypropylene melt which melts the resin having a melt index of 5-12 and exits through the spinneret is in the state of the polypropylene undrawn yarn cooled before the first goat roll.

The polypropylene undrawn yarn is stretched in a multi-stage roller, and after being subjected to a heat fixation process in a roller, the polypropylene undrawn yarn is wound on a roller rotating at high speed after a relaxation process.

Here, considering the characteristics of the polypropylene resin chips having the respective melt indexes of 5 to 12, melt spinning was carried out at an appropriate spinning temperature, and the high strength and low shrinkage characteristics superior to the conventional industrial polypropylene yarns were exhibited by varying the draw ratio and the relaxation rate To produce superior polypropylene yarns.

Under the spinning conditions of the present invention, the intrinsic viscosity of the polypropylene resin chip is preferably 5 to 12, and when the melt index is less than 5, the melt fracture phenomenon is serious and the radiation tension is high, Is more than 12, there is a problem that the strength is difficult to manifest due to the low molecular weight.

The cylinder temperature of the extruder is preferably in the range of 170 to 200 ° C. If the cylinder temperature is lower than 170 ° C., the melt temperature may be low to cause a problem of inhomogeneity of the melt due to the generation of cosmetic material, and excessive shearing stress may occur in the extruder When the temperature of the cylinder exceeds 200 ° C, the pyrolysis of the polypropylene melt accelerates and the physical properties at the target level may become difficult to manifest. Thereafter, the radiation beam, the hood, the gear pump temperature and the cooling conditions can be carried out according to ordinary conditions.

Under these conditions, the prepared non-drawn yarn is passed through a multi-stage high-precision deterioration roller and subjected to a stretching-heat fixing-relaxation-winding process.

When the stretching ratio is less than 5.5, the fiber orientation is low and the strength development is difficult. When the stretching ratio is more than 6.0, the degree of shrinkage becomes excessive and the shrinkage ratio is excessively increased. If this condition becomes bad and the situation continues, full embezzlement may occur.

The relaxation rate is preferably from 8 to 12%, and if it is less than 8%, the shrinkage rate is difficult to manifest. If the ratio is more than 12%, the flicker on the roller is worsened and workability can not be ensured.

If the temperature is lower than 150 ° C, the heat transfer amount to the yarn is insufficient and the relaxation efficiency is low to achieve a shrinkage rate. If the temperature exceeds 160 ° C, The strength is lowered and tar generation due to carbonization of the roller-phase emulsion component is increased, so that the workability may be lowered.

Example

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the above-described embodiments. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

The measuring method in the examples is shown below

1. Melt index (M.I)

The amount of the resin flowing at 230 占 폚 under a load of 2.16 kgf for 10 minutes by the ASTM D1238 method is measured

2. How to measure the strength of yarn

The yarn is allowed to stand for 24 hours under a standard condition, that is, in a temperature and humidity chamber at a temperature of 25 ° C and a relative humidity of 65%, and then the sample is measured by a tensile tester by the method of ASTM D-885.

3. Method to measure dry heat shrinkage rate

The yarn is allowed to stand in a standard state, that is, a constant temperature and humidity chamber at a temperature of 25 DEG C and a relative humidity of 65% for 24 hours. Leave in the oven at 190 캜 for 5 minutes. Allow the yarn to stand for 24 hours under standard conditions. The shrinkage percentage of the yarn is measured according to the following equation.

Shrinkage (%) = (L0-L1) / L0 100

In the above equation,

L0 is the length of the sample measured under ultra-high load (0.01 g / d) after 24 hours' standing in the standard state, and L1 is the length of the sample reduced under the ultra-high load (0.01 g / d)

Example  1 to 5

A polypropylene fiber was produced as follows using an apparatus for producing a polypropylene fiber according to an embodiment of the present invention shown in FIG.

A polypropylene chip having a melt index of 5 to 12 was put into the extruder 1 and the spinning temperature was set to 250 DEG C and the hole diameter of the spinneret 2 was set at 0.5 mm , The molten polymer is extruded through a nozzle 3 having a number of holes of 192 and is cooled with quench air at 20 to 25 ° C using a cooling device 4 and then passed through a spin tube The spinning oil emulsion was attached using the spinning emulsion applying device 5, the unstirred yarn with the emulsion was once wound at 400 m / min, and then the godet roller 6 in the box 7 was wound Followed by stretching and heat treatment. Thereafter, using the entanglement apparatus 8 and the winder 9, the resulting product was wound into a fineness of 1,000 denier.

Specifically, polypropylene fibers were prepared by spinning and stretching under the spinning and drawing conditions shown in Table 1 below.

The physical properties of the prepared polypropylene fiber were measured, and the results of the total draw ratio and the physical properties of the drawn product are shown in Table 1. In each of the examples, the melt index, the extrusion temperature (cylinder temperature of the extruder), the stretching ratio, the relaxation rate, and the relaxation temperature were the same as those in Table 1 and the other spinning conditions were the same.

According to the following Table 1, it was confirmed that the strength of the polypropylene fibers of Examples 1 to 5 was 7.0 g / d or more and the heat shrinkage rate was 5% or more.

Example 1 Example 2 Example 3 Example 4 Example 5 Melt Index 10 10 12 12 12 Extrusion temperature 180 170 200 190 180 Stretching cost 6.00 5.7 5.8 6.0 6.0 Relaxation rate 10 8 8 10 12 Relaxation temperature 155 150 160 155 155 burglar 8.0 7.5 7.2 7.5 7.3 Shindo 30 25 28 25 27 Dry heat shrinkage 5 5 3 4 3 Exterior Good Good Good Good Good

Comparative Example  1 to 7

A polypropylene fiber was prepared in the same manner as in Example 1, except that the fiber was spinnable and drawn at a melt index extrusion temperature, a stretch ratio, a relaxation rate, a relaxation temperature, and the like in Table 2 below.

The properties of the obtained polypropylene fibers were measured, and the results are shown in Table 2.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Melt Index 3 15 12 12 10 10 10 Extrusion temperature 180 180 160 250 180 180 180 Stretching cost 6.0 6.0 6.0 6.0 5.5 6.0 6.0 Relaxation rate 10 10 10 10 10 5 10 Relaxation temperature 155 155 155 155 155 155 120 burglar 8.5 6.5 - 6.8 6.8 7.7 8.0 Shindo 20 35 - 32 35 23 20 Dry heat shrinkage 10 3 - 3 4 10 15 Exterior Bad Good Fineness
Unevenness Good Good Good Good

In Comparative Example 1, a resin having a low melt index was used, an excessive tension was applied in the stretching process, resulting in poor appearance due to mold and the like and a high heat shrinkage ratio. In Comparative Example 2, Strength was not expressed.

Also, in Comparative Example 3, the extrusion temperature was too low to cause significant fluidity change due to non-uniform melting, resulting in serious quality unevenness in the fineness of the finished product from 950 denier to 1,100 denier. In Comparative Example 4, the extrusion temperature was too high The strength of the unstretched yarn was so low that the strength was lowered even in the final yarn.

In the case of Comparative Example 5, the stretching ratio was low and the strength development was not sufficiently manifested in the final yarn. In Comparative Example 6, the relaxation rate was too low, the orientation stress was not sufficiently eliminated, The relaxation temperature was too low to be wound without sufficient heat fixation, and the shrinkage ratio in the final yarn was increased.

1: extruder, 2: spinneret, 3: nozzle, 4: cooling device
5: radial emulsion applying device, 6: high-precision roller, 7: box, 8: interlocking device 9: winder

Claims (5)

Melt-spinning a polypropylene resin having a melt index of 10 to 12 g / 10 min and cooling and solidifying to form an undrawn yarn; And
Stretching the stretched non-drawn yarn using a multi-stage stretching roller;
In the step of forming the non-drawn filament, the temperature of the cylinder of the extruder for melt-spinning the polypropylene resin is adjusted to 170 to 200 캜,
The stretching step is carried out at a stretching ratio of 5.7 to 6.0,
Wherein the relaxation process is performed at a relaxation rate of 8% to 12% and a relaxation zone temperature of 150 to 160 ° C,
Wherein the winding process is carried out at a winding speed of at least 2,500 m / min to have a strength of 7.0 to 8.0 g / d, an elongation of 25 to 30% and a shrinkage of 5% or less. delete delete A high strength, low shrinkage polypropylene fiber produced by the process of claim 1. delete

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