KR100960819B1 - High-strength polypropylene fiber and its manufacturing method - Google Patents

Abstract

 The present invention relates to a method for producing a high strength polypropylene fiber (polyproplene fiber) and the high strength polypropylene fiber (polyproplene fiber), more specifically a high molecular weight polypropylene resin (polypropylene resin), a solvent and an antioxidant Dissolving the mixture to prepare a mixed solution; Spinning the mixed solution to form an undrawn yarn (II); And extracting the solvent in the undrawn yarn with an extracting agent, stretching and heat-setting to complete the fiber III; and a method for producing high-strength polypropylene fiber, characterized in that it comprises a It is about.

The high molecular weight polypropylene resin (polypropylene resin) is characterized in that the weight average molecular weight is 300,000g / mol to 1,000,000g / mol, the tacticity is 90 to 100%, the stretching in the step III is 1 It consists of a multi-stage including step, step 2 and step 3, and in the first step, the undrawn yarn is drawn 1 to 8 times at 100 to 150 ℃, in the second step undrawn yarn (undrawn yarn) 2 to 6 times stretching at 120 to 170 ℃, the third step is characterized in that the undrawn yarn (stretched undrawn yarn 1.2 to 5 times at 145 to 180 ℃).

High Strength Fiber, High Molecular Weight Polypropylene Resin, Gel Spinning, Stretching

Description

High strength polyproplene fiber and method for manufacturing the same

 The present invention relates to a method for producing a high strength polypropylene fiber (polyproplene fiber) and the high strength polypropylene fiber (polyproplene fiber), more specifically a high molecular weight polypropylene resin (polypropylene resin), a solvent and an antioxidant Dissolving the mixture to prepare a mixed solution; Spinning the mixed solution to form an undrawn yarn (II); And extracting the solvent in the undrawn yarn with an extractant, stretching and heat-setting to complete the fiber III; and a method for producing high-strength polypropylene fiber, characterized in that it comprises a It relates to a product using the same.

A technique for preparing fibers by gel spinning high molecular weight polyethylene (polyethylene) was first proposed in 1980 by Paul Smith, et al (Germany Patent 300469). The technology at that time is a method of melting high molecular weight polyethylene (polyethylene) in a relatively low concentration in a volatile solvent and then cooling to prepare a gel fiber and then stretch the high magnification to produce a high strength polyethylene fiber (polyethylene fiber). However, the technique is not environmentally friendly because it uses a volatile solvent, the creep characteristics of the fiber is poor, the use temperature is low, the dimensional stability is greatly limited due to the problem of application to the product.

Polypropylene is one of the larger types of alkyl polymers in addition to polyethylene, and has excellent thermal performance, flowability, creep resistance, and processability compared to polyethylene. However, the crystallization rate is slower than polyethylene, and the crystallinity is also lower than that of polyethylene. In order to compensate for these problems, US Patent No. 5,470,898 discloses a method for preparing a polymer alkyl mixture using sorbitol derivatives as nucleating agents and additives for improving transparency, and Chinese Patent 2007100378710 adds nucleating agents. A method of producing high strength polyproplene fibers by gel spinning a solution is disclosed. This method effectively increases the crystallinity and transparency of the film or textile product, but the production cost increases with the addition of the nucleating agent, and has the disadvantage of causing the non-uniformity of the fiber structure due to the non-uniform distribution of the nucleating agent. In addition, the addition of the nucleating agent has a problem of destroying the regularity of the polymer structure and lowering the performance of the fiber.

The present invention has been made to solve the above problems, step I of preparing a mixed solution by dissolving a mixture of a high molecular weight polypropylene resin (polypropylene resin), a solvent and an antioxidant; Spinning the mixed solution to form an undrawn yarn (II); And step III of extracting the solvent in the undrawn yarn with an extractant, stretching and heat-setting to complete the fiber; the process is simple, and the nucleating agent is not added. It is an object of the present invention to provide a method for producing a high-strength polypropylene fiber having high mechanical properties, thermal properties, and creep resistance.

Method for producing a high strength fiber using a high molecular weight polypropylene resin according to the present invention for achieving the above object is to prepare a mixed solution by dissolving a mixture of a high molecular weight polypropylene resin, a solvent and an antioxidant Step I; Spinning the mixed solution to form an undrawn yarn (II); And step III of extracting the solvent in the undrawn yarn with an extractant, stretching and heat-setting to complete the fiber.

Preferably, the high molecular weight polypropylene resin has a weight average molecular weight of 300,000 g / mol to 1,000,000 g / mol and a tacticity of 90 to 100%.

Preferably, the solvent of step I is characterized in that it is selected from paraffin oil, aromatic hydrocarbon compound, saturated aliphatic hydrocarbon compound.

Preferably, the mixed solution of step I is made by dissolving the mixture at a temperature of 80 to 200 ℃, characterized in that the concentration of the high molecular weight polypropylene resin (polypropylene resin) is 5 to 75wt.%.

Preferably, the undrawn yarn of step II is characterized in that it is formed by cooling in water of 0 ℃ to 35 ℃ after spinning the mixed solution of step I.

Preferably, the spinning of step II is a gel spinning (gel spinning), the draft ratio (Draft ratio) is a method for producing a high-strength polypropylene fiber, characterized in that 10 to 30.

Preferably, the extractant in step III is characterized in that selected from 1,2-dimethylbenzene (1,2-dimethylbenzene), normal hexane (n-hexane), gasoline (gasoline) and hydrocarbon compounds.

Preferably, the stretching in step III is made in a multi-stage including one step, two steps and three steps, in the first step to draw an undrawn yarn 1 to 8 times at 100 to 150 ℃ In the second step, the undrawn yarn is drawn 2 to 6 times at 120 to 170 ° C, and in the third step, the undrawn yarn is drawn at 1.2 to 5 times at 145 to 180 ° C. do.

Preferably, the heat setting in step III is characterized in that it is made at 120 to 210 ℃ after stretching.

In addition, the high-strength fibers using a high molecular weight polypropylene resin according to the present invention for achieving the above object is manufactured in any one of the above-described method, the melting point of 160 ℃ or more, creep (strain) 8% Below, the fineness is 1.1dtex or more, the cutting strength is characterized in that 0.4 ~ 2.0GPa and the initial modulus 10 ~ 38GPa.

Preferably, the product using the high-strength polypropylene fiber (polyproplene fiber) according to the present invention for achieving the above object has the characteristics as described above.

As described above, according to the manufacturing method of the high strength fiber using the high molecular weight polypropylene resin according to the present invention as described above, the strength of the polypropylene fiber was improved by using a polypropylene resin and through a multi-step stretching process, The manufacturing process is simple and there is no economic effect because no nucleating agent is added at the time of manufacture.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 is a flowchart briefly showing the manufacturing method of the present invention.

Referring to Figure 1, the high-strength polypropylene fiber of the present invention is prepared by dissolving a mixture of a high molecular weight polypropylene resin (polypropylene resin), a solvent and an antioxidant to prepare a mixed solution; Spinning the mixed solution to form an undrawn yarn (II); And step III of extracting the solvent in the undrawn yarn with an extractant, stretching and heat-setting to complete the fiber.

The high molecular weight polypropylene resin has a weight average molecular weight of 300,000 g / mol to 1,000,000 g / mol and a tacticity of 90 to 100%. The polypropylene can be obtained by decomposition of petroleum (naphtha). The polypropylene is contacted with a Ziegler-Natta catalyst in a solution and polymerized at room temperature to 80 ° C. and 3 to 10 kg / cm 2 to obtain a stereopropylene (isotactic polypropylene) having stereoregularity.

Since the polypropylene contains a little bit of atactic polypropylene, which has no stereoregularity and a low softening point, the polypropylene is extracted and separated using a boiling fenton, and the stereoregular polymer content is 90 to 90. It is about 100%. In addition to using the Ziegler-Natta catalyst described above, various methods are carried out, all of which are characterized by obtaining a stereoregular polymer. In addition, it may be prepared by copolymerizing ethylene, other olefin types or vinyl monomers, or by blending other polymers.

The tacticity refers to the chemical and geometric regularity of the molecular structure of the polymer. The three-dimensional chain structure of the polymer is influenced by the structural regularity of the chain, free vibration and rotation, bond-inducing specific groups between the molecules and substituents of the chain. Regular polymers are those in which one continuous array contains only one type of repeating steric array. The polymer having a high tacticity is suitable for producing high strength polypropylene because it has a high melting point and is not easily dissolved in a crystalline form.

In step I, a high molecular weight polypropylene, an antioxidant, and a solvent are mixed to prepare a mixture. The solvent is selected from paraffin oil, aromatic hydrocarbon compound and saturated aliphatic hydrocarbon compound. The solvent is used to dilute the high molecular weight polypropylene. Specifically, for example, n-nonane, n-decane, n-undecane, n-dodecane, n-dodecane, n-tetra Aliphatic hydrocarbon solvents such as n-tetradecane, n-octadecane, liquid paraffin and kerosene; Xylene, naphthalene, tetralin, butylbenzene, p-cemen, cyclohexyl benzene, diethyl benzene, pentyl benzene aromatic hydrocarbon solvents such as pentyl benzene, dodecylbenzene, bicyclohexyl, decalin, methylnaphthalene, ethylnaphthalene, and hydrogenated derivatives thereof; 1,1,2,2-tetrachloroethane (1,1,2,2-tetrachloroethane), pentachloroethane, hexachloroethane, 1,2,3-trichloropropane (1,2 Halogenated hydrocarbon solvents such as, 3-trichloropropane, dichlorobenzene, 1,2,4, -trichlorobenzene (1,2,4, -trichlorobenzene) and bromobenzene; And mineral oils such as paraffinic processor oil, naphthenic process oil, and aromatic process oil.

Although a wax can be used as the said solvent, As a wax suitable as the said solvent, an aliphatic hydrocarbon compound and its derivative are mentioned specifically ,. The aliphatic hydrocarbon compounds used as waxes are those containing mainly saturated aliphatic hydrocarbon compounds, and are usually called "paraffin waxes" having a molecular weight of 2000 or less, preferably 1000 or less, and more preferably 800 or less. As these aliphatic hydrocarbon compounds, Specifically, n-alkanes of 22 or more carbon atoms, such as tocosan, tricosan, tetracosan, and triacontane; A low-pressure polyethylene wax, a high pressure method, which is a low molecular weight polymer obtained by copolymerizing a mixture of lower n-alkanes mainly composed of these n-alkanes with so-called paraffin wax separated from petroleum, ethylene or ethylene and other α-olefins. Waxes obtained by lowering molecular weight of polyethylene such as polyethylene wax, ethylene copolymer wax or medium-low pressure polyethylene, high pressure polyethylene, etc. by heat degradation or the like and oxides of these waxes; Maleic acid modified oxide waxes; Maleic acid modified wax is used.

The aliphatic hydrocarbon compound derivative is, for example, one or more, preferably 1 to 2, particularly preferably 1 carboxyl group, hydroxyl group or carbamo at the terminal or inside of the aliphatic hydrocarbon (alkyl group, alkenyl group). Fatty acids, aliphatic alcohols having a functional group such as a diary, an ester group, a mercapto group, a carbonyl group, and having 8 or more carbon atoms, preferably 12 to 50 carbon atoms, or a molecular weight of 130 to 2000, preferably 200 to 800; Fatty acid amides, fatty acid esters, aliphatic mercaptans, aliphatic aldehydes, aliphatic ketones and the like are used. Specifically, caprinic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, fatty acid, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, fatty acid amide, caprinamide, laurin As the amide, palmitine amide, stearin amide, fatty acid ester, stearyl acetate ester and the like are used.

Antioxidants included in the mixture of step I may be used a low molecular weight phenols or aromatic amines, may be selected from the class of organic phosphites.

A mixed solution is prepared by dissolving a mixture of the high molecular weight polypropylene resin, a solvent, and an antioxidant. The mixed solution of step I is prepared by dissolving the mixture at a temperature of 80 to 200 ℃, the concentration of the high molecular weight polypropylene resin (polypropylene resin) is 5 to 75wt.%. When the concentration of the high molecular weight polypropylene resin (polypropylene resin) is 5wt.% Or less, the concentration of the mixed solution is too thin to produce a high strength polypropylene (polypropylene). In addition, when the concentration of the high molecular weight polypropylene resin (polypropylene resin) is 75wt.% Or more, the viscosity is too large to prepare a mixed solution, it is preferable to manufacture within the concentration range.

Step II spins the mixed solution to form an undrawn yarn. Spinning of the step II is a gel spinning (gel spinning) so that the draft ratio (Draft ratio) is 10 to 30. If the draft ratio is 10 or less, there is a problem that the orientation effect is lowered and the workability is lowered during the stretching process. In addition, when the draft ratio is 30 or more, multi-step stretching is impossible due to excessive molecular orientation, and there is a problem in that physical properties of the fiber decrease after stretching. Therefore, it is preferable to make it within the range of the said draft ratio. Here, the draft ratio may be defined as the ratio of the extrusion rate V ₀ of the resin to the pulling rate V of the cooled solidified unstretched fiber.

Spinning in step II uses a gel spinning method. Melt spinning, dry spinning, wet spinning and emulsion spinning are common methods for spinning. In addition, there is a new special spinning method, the fiber produced by the special spinning method has a high strength, high modulus. The special spinning method includes liquid crystal spinning, gel spinning, mixed spinning between incompatible components, composite spinning and mixed spinning. Among them, the present invention uses a gel spinning method (gel spinning), the gel spinning (gel spinning) is a spinning method having a higher strength than Kevlar, the difference from the conventional spinning is a special characteristic of the spinning stock solution and the structure and molecular weight of the polymer Depends on The polymer capable of gel spinning (gel spinning) should have a complete alignment structure, be structurally flawless, have a high polymerization degree and a high molecular weight. Since the polypropylene resin in the present invention is a high molecular weight polypropylene having a weight average molecular weight of 300,000 g / mol to 1,000,000 g / mol, it is preferable to use the spinning method. However, the method of increasing the strength of the high molecular weight polypropylene is not limited thereto.

The gel spinning (gel spinning) is a spinning method that is generally fiberized via the gel state of the polymer polymer solution (solvent: naphthalene, mineral oil, paraffin oil) → delivery pump → spinneret → cooling extraction bath → oven (oven) → unburned Gentleman → high magnification stretching → high strength, high modulus fibers are manufactured.

The undrawn yarn of step II is formed by spinning the mixed solution of step I after cooling in water at 0 ° C to 35 ° C. The undrawn yarn refers to a fiber with less stretching in the spinning process. In step III, the extractant is extracted to extract the solvent in the undrawn yarn. The solvent is a barrier to molecular orientation through the stretching of the fiber is to extract the solvent.

In step III, the solvent in the undrawn yarn is extracted with an extractant, stretched and heat-set to complete the fiber. The extractant in step III is selected from 1,2-dimethylbenzene, n-hexane, gasoline and hydrocarbon compounds. The 1,2-dimethylbenzene, n-hexane, gasoline, and hydrocarbon compounds are paraffin oils, aromatic hydrocarbon compounds, and saturated aliphatic hydrocarbon compounds. It is suitable as an extractant to extract the back.

In the step III, the drawing is sequentially performed in a multi-step including one step, two steps and three steps, in the first step, an undrawn yarn is drawn 1 to 8 times at 100 to 150 ° C., and the second step In the drawing, undrawn yarn is drawn 2 to 6 times at 120 to 170 ° C, and in the third step, the undrawn yarn is drawn at 1.2 to 5 times at 145 to 180 ° C. Stretching as described above is to increase the molecular orientation of the polymer polypropylene fiber (polyproplene fiber). When the molecular orientation is improved, the physical properties of the fiber are also improved. Therefore, the strength of the physical properties of the polypropylene of the present invention is increased through the multi-stage stretching.

The stretching in step III must be carried out within the desired temperature range for each step. If the temperature is higher than the above temperature range, the degree of freedom of molecules is increased, so that the orientation of molecules is not well achieved. In addition, when the temperature is lower than the temperature range, the stretching is not performed well, and the polypropylene fiber is not stretched and breaks occur. Therefore, the multi-stage stretching is preferably performed in the above temperature range for each stage.

After the multi-step stretching, heat setting at 120 ~ 210 ℃ to complete the final high molecular weight high strength polypropylene fiber (polyproplene fiber). The reason for heat setting as described above is to impart structural stability of the fiber after the stretching orientation. The heat setting in the temperature range makes it possible for the fiber molecules oriented through the stretching process to continuously maintain the oriented molecular state within the temperature range. By maintaining the oriented molecular state, strength, which is a physical property, also appears stably. When the temperature of the heat setting is 120 ° C or less, the heat setting is not performed, and when the temperature is 210 ° C or more, the molecular chains oriented in the fiber are scattered, so that the degree of orientation is lowered.

As described above, the polypropylene fibers prepared by the steps I, II, and III have a melting point of 160 ° C. or higher, creep (strain) of 8% or less, fineness of 1.1 dtex or more, and cutting strength of 0.4 to 2.0. GPa and an initial modulus of 10 to 38 GPa. Such high-strength propylene fiber (polyproplene fiber) can be used in a variety of industrial products, such as wires, sails, fishing nets, filter cloth, sporting goods, bulletproof, protective, protective gloves, pressure-resistant containers.

Hereinafter, the production method and effects thereof of the present invention will be described in detail through Examples and Comparative Examples. However, these examples and comparative examples are only intended to illustrate the invention by way of example, it will be clear that it is not intended to limit the scope of the invention only to these embodiments.

Example 1

A high molecular weight polypropylene powder having a molecular weight of 800,000 g / mol and a stereoregularity of 99% is added to paraffin oil. The concentration of polypropylene powder at this time is 20% by weight. The temperature is gradually increased in a temperature range of 130 to 175 ° C for 10 minutes to dissolve the polypropylene powder. The temperature raising condition is a total of three stages, the first stage 130 ℃, the second stage 170 ℃, the third stage proceeds to 180 ℃. A metering pump is used to supply a pressure of 2 MPa at 180 ° C. of the dissolved polypropylene solution to feed into the spinning machine. It spins by applying a pressure of 4 MPa at 180 ° C. through a spinneret with a hole of 0.6 mm in diameter. The spun polyproplene fiber is solidified using a 0 ° C. cooling bath containing ice to form gel fibers that are not drawn. The molded gel fibers are predrawn at twice the normal temperature. Extract for 5 minutes in gasoline. First stretch 5 times at 135 ° C. Second extraction in gasoline for 3 minutes. 2.5 times 2nd extension at 150 degreeC, 2 times 3rd extension is carried out at 162 degreeC. After hot air drying at 50 ° C. for 5 minutes, heat-set at 170 ° C.

Example 2-

The solvent used in the manufacture of the fiber in the same manner as in Example 1 was an aromatic hydrocarbon compound.

Example 3-

The molecular weight of the high molecular weight polypropylene used in preparing the fibers in the same manner as in Example 1 was 400,000 g / mol.

Example 4

The stereoregularity of the ultrahigh molecular weight isotropic polypropylene used in producing the fiber in the same manner as in Example 1 was 92%.

Comparative Example 1

In preparing the fiber in the same manner as in Example 1, a nucleating agent (trade name: Hyperform, Milliken Chemical) was used.

Strength and Modulus

Using a tensile strength tester (UTM, Instron, USA), a strain-stress curve is obtained by measuring at a sample length of 200 mm, an elongation rate of 100% / min, a relative humidity of 65%, and a temperature of 25 ° C, and at the break point of the obtained curve. The average value of the strengths calculated from the stresses was calculated. The experiment was repeated 10 times in total.

Creep experiment

Measurement was performed for 60 minutes by applying a force of 0.2 GPa at 100 ° C.

Differential Scanning Calorimetry

Thermal properties such as melting temperature were measured using a differential scanning calorimeter (DSC, PerkinElmer, USA). The sample was cut to 5 mm or less, filled and enclosed with about 5 mg in an aluminum pan, and 200 ° C. from room temperature at a temperature rising rate of 10 ° C./min under completely inert gas with the same empty aluminum pan as a guide. The temperature was raised to obtain the elevated temperature DSC curve.

The properties of the fibers produced by Examples 1 to 4 and Comparative Example 1 are shown in Table 1 below.
Item Fineness (dtex) Cutting strength
(GPa) Initial modulus
(GPa) Cutting elongation (%) Creep Rate (%) Melting temperature (℃) Example 1 3.3 1.21 28.1 9.9 2 177.2 Example 2 3.3 1.35 33.1 8.9 3 179.9 Example 3 3.3 1.12 22.5 9.4 2 175.3 Example 4 3.3 1.02 21.7 9.9 2 173.8 Comparative Example 1 3.3 1.12 16.9 11.9 6 171.0

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On the other hand, the present invention relates to a method for producing a high strength fiber using a high molecular weight polypropylene resin (polypropylene resin) to dissolve a mixture of a high molecular weight polypropylene resin (polypropylene resin), a solvent and an antioxidant to prepare a mixed solution Step I, step II of spinning the mixed solution to form an undrawn yarn, and extracting the solvent in the undrawn yarn with an extractant, stretching and heat setting to complete the fiber III; It is made, including. The high molecular weight polypropylene resin (polypropylene resin) has a weight average molecular weight of 300,000g / mol to 1,000,000g / mol, the tacticity of 90 to 100% of the polypropylene fiber of the present invention (polyproplene fiber) Increased the intensity.

In addition, in the present invention, without using a nucleating agent, the mixed solution is gel-spun (gel spinning) so that the draft ratio is 10 to 30 to form an undrawn yarn to improve the strength of the fiber . In addition, the degree of molecular orientation in the polypropylene fiber was increased through multi-step stretching of the undrawn yarn, and the strength of the fiber was increased due to the improved degree of molecular orientation.

The high-strength polypropylene fiber produced by the manufacturing method of the present invention as described above is suitable as an industrial product, the invention is useful as a material that can replace metal as a material for building, automobile, machinery, etc. to be.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. . Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a flow chart briefly showing the manufacturing method of the present invention.

Claims (11)

In the manufacturing method of high strength fiber using a high molecular weight polypropylene resin, Preparing a mixed solution by dissolving a mixture of a high molecular weight polypropylene resin, a solvent and an antioxidant; Spinning the mixed solution to form undrawn yarn II; And And extracting the solvent in the unstretched yarn with an extractant, stretching and heat-setting to complete the fiber III. The method of claim 1, The high molecular weight polypropylene resin (polypropylene resin) has a weight average molecular weight of 300,000g / mol to 1,000,000g / mol, the tacticity of 90 to 100%, characterized in that the manufacturing method of high strength polypropylene fiber. The method of claim 1, The solvent of step I is selected from paraffin oil, aromatic hydrocarbon compound and saturated aliphatic hydrocarbon compound. The method of claim 1, The mixed solution of step I is prepared by dissolving the mixture at a temperature of 80 to 200 ℃, the production of high-strength polypropylene fiber, characterized in that the concentration of the high molecular weight polypropylene resin (polypropylene resin) is 5 to 75wt.%. Way. The method of claim 1, The non-stretched yarn of step II is formed by spinning in the water of 0 ℃ to 35 ℃ after spinning the mixed solution of step I. The method of claim 1, The spinning of step II is a gel spinning (gel spinning), the draft ratio (Draft ratio) is a method of producing a high-strength polypropylene fiber, characterized in that 10 to 30. The method of claim 1, Extractor in step III is a method for producing high strength polypropylene fibers, characterized in that selected from 1,2-dimethylbenzene (1,2-dimethylbenzene), normal hexane (n-hexane), gasoline (gasoline) and hydrocarbon compounds . The method of claim 1, In the step III, the stretching is sequentially performed in a multi-step including one step, two steps, and three steps, in the first step, the undrawn yarn is drawn 1 to 8 times at 100 to 150 ℃, in the second step the undrawn yarn Stretching 2 to 6 times at 120 to 170 ℃, in the third step is a method for producing a high-strength polypropylene fiber, characterized in that the stretched undrawn yarn 1.2 to 5 times at 145 to 180 ℃. The method of claim 1, Heat-setting in the step III is a method for producing a high strength polypropylene fiber, characterized in that made at 120 to 210 ℃ after stretching. It is manufactured by the manufacturing method as described in any one of Claims 1-9, It has melting | fusing point 160 degreeC or more, Creep (strain) rate 8% or less, Fineness 1.1dtex or more, Cutting strength 0.4-2.0GPa, and initial modulus 10 High strength polypropylene fiber, characterized in that ~ 38GPa. The product using the high strength polypropylene fiber of Claim 10.

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