KR102600514B1 - Polypropylene resin, polypropylene fiber and method for preparing the same - Google Patents

Abstract

The present invention relates to a polypropylene resin that exhibits excellent workability and can be fine-tuned, a polypropylene fiber containing the same, and a method for manufacturing the same.

Description

Polypropylene resin, polypropylene fiber, and method for producing the same {POLYPROPYLENE RESIN, POLYPROPYLENE FIBER AND METHOD FOR PREPARING THE SAME}

The present invention relates to a polypropylene resin that exhibits excellent workability and can be fine-tuned, a polypropylene fiber containing the same, and a method for manufacturing the same.

Polypropylene resin has been used as a general-purpose resin in various fields due to its low specific gravity, high heat resistance, and excellent processability and chemical resistance.

Polypropylene resin has been used in a variety of ways in the automobile industry, and fibers manufactured using the meltblown method have also been applied as sound-absorbing materials inside automobiles. Typically, high-flow polypropylene with MI 1500 or higher is widely used for meltblown fibers, and in the textile industry, homo-polypropylene with an increased MI is applied to improve sound absorption properties when applying sound absorbing materials as final products by increasing fineness. Alternatively, various studies are in progress, such as controlling radiation conditions such as hot air temperature/pressure.

Ultra-high-flow homopolypropylene using a general-purpose Ziegler-Natta catalyst uses a peroxide-based decomposition accelerator in the extrusion process of low MI materials due to low hydrogen reactivity, using vis-breaking or controlled rheology. ; CR) process, it is possible to produce high-flow products with increased MI compared to conventional products. However, due to the limitations of catalysts with multiple active sites and limitations in the CR process, the molecular weight distribution exceeded 3, making it difficult to increase fibrillation when applied to fiber applications.

In addition, in order to increase MI compared to the past, an excessive amount of peroxide was used, resulting in excessive Hume generation during melt-blown processing, which deteriorated workability during the spinning process, and also caused environmental problems due to high TVOC.

Accordingly, there was an attempt to apply homo-polypropylene, which has increased MI compared to the conventional high-flow polypropylene, to the meltblown method based on a metallocene catalyst that can realize ultra-high flow and narrow molecular weight distribution without using peroxide. When changing spinning conditions (increasing hot air temperature and pressure) or applying products with MI 1800 or higher, there was a limit to the production of ultrafine fibers due to the occurrence of fly during the spinning process. Accordingly, it was impossible to produce sound-absorbing materials in which new ultrafine fibers were distributed, and there was also a problem that the sound-absorbing effect in the high frequency range required for electric vehicle fields was deteriorated.

Accordingly, it is necessary to develop a resin that satisfies all the environmental friendliness, workability, and fineness required for the product.

Accordingly, the present invention is intended to provide a polypropylene resin that exhibits excellent workability and can be finely divided, a polypropylene fiber containing the same, and a method for manufacturing the same.

In order to solve the above problems, the present invention provides a polypropylene resin that includes a homopolypropylene polymer and satisfies the following conditions i) to iii):

i) the average particle diameter is 1,200 ㎛ to 2,500 ㎛,

ii) a melt index of 1,700 g/10 min to 3,500 g/10 min measured at 230° C. with a load of 2.16 kg according to ASTM D1238;

iii) the crystallization on set temperature (T ₁ ) is 127°C or higher, and the crystallization on set temperature (T ₁ ) is the initial temperature at a point where the viscosity change ratio expressed by Equation 1 below is 190 or higher,

[Equation 1]

Viscosity change rate = V ₂ (T ₂ ) / V ₁ (T ₁ )

In the formula, V ₁ (T ₁ ) and V ₂ (T ₂ ) are the shear rate of polypropylene resin 1 s ^-1 Below, the complex viscosity (Pa·s) measured at temperatures T ₁ and T ₂ while decreasing temperature from 180 ℃ at a rate of 1 ℃/min,

T ₁ is the crystallization on set temperature,

T ₂ is a temperature 3°C lower than the crystallization on set temperature (T ₁ ).

According to another embodiment of the invention, a polypropylene fiber containing the above-described polypropylene resin is provided.

According to another embodiment of the invention, a method for producing polypropylene fibers containing the above-described polypropylene resin is provided.

Specifically, in the presence of a catalyst composition comprising a transition metal compound represented by the following formula (1), a silica carrier, and an alkylaluminoxane-based cocatalyst, hydrogen is added in an amount of 1,000 ppm to 2,000 ppm and propylene monomer is polymerized to produce homopolymer. Preparing a polypropylene resin comprising a propylene polymer; and

A step of producing a fiber by melt spinning while injecting air at a temperature of 240°C to 270°C into the polypropylene resin at a pressure of 1.8 psi to 2.3 psi,

The polypropylene resin includes satisfying the following conditions i) to iii):

i) the average particle diameter is 1,200 ㎛ to 2,500 ㎛,

ii) a melt index of 1,700 g/10 min to 3,500 g/10 min measured at 230° C. with a load of 2.16 kg according to ASTM D1238;

iii) the crystallization on set temperature (T ₁ ) is 127°C or higher, and the crystallization on set temperature (T ₁ ) is the initial temperature at a point where the viscosity change ratio expressed by Equation 1 below is 190 or higher,

[Equation 1]

Viscosity change rate = V ₂ (T ₂ ) / V ₁ (T ₁ )

In the formula, V ₁ (T ₁ ) and V ₂ (T ₂ ) are the shear rate of polypropylene resin 1 s ^-1 Below, the complex viscosity (Pa·s) measured at temperatures T ₁ and T ₂ while decreasing temperature from 180 ℃ at a rate of 1 ℃/min,

T ₁ is the crystallization on set temperature,

T ₂ is 3°C lower than the crystallization on set temperature (T ₁ ):

[Formula 1]

In Formula 1,

X ₁ and X ₂ are each independently halogen,

R ₁ and R ₅ are each independently C _6-20 aryl substituted with C _1-20 alkyl,

R ₂ to R ₄ and R ₆ to R ₈ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 Alkoxysilyl, C _1-20 ether, C _1-20 silyl ether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,

A is carbon, silicon or germanium.

The polypropylene resin composition according to the present invention satisfies specific crystallization behavior parameters, thereby significantly reducing the generation of FLY in the fiberization process, making it easy to fine-fine, and at the same time, productivity is significantly improved.

Figure 1 is a schematic diagram showing the meltblown spinning process.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise,” “comprise,” or “have” are intended to designate the presence of implemented features, steps, components, or a combination thereof, and are intended to indicate the presence of one or more other features or steps, It should be understood that the existence or addition possibility of components or combinations thereof is not excluded in advance.

Since the invention can be subject to various changes and can take various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the invention.

Hereinafter, polypropylene resin, fibers containing it, and methods for producing polypropylene-based fibers will be described according to specific embodiments of the invention.

Among commonly used metallocene polypropylene resins for meltblown, products with a melt index (MI) of 1,800 g/10min or higher are difficult to produce in pellet form due to their low viscosity characteristics, so they are produced in powder or flake-type. do. However, in the case of powdered polypropylene resin, due to the small particle size, there was a problem of unstable spinning stability during melt blown spinning, such as unstable input of raw materials and decreased feeding amount. In addition, when changing spinning conditions for fine fiberization (increasing hot air temperature and pressure), there was a problem in producing ultrafine fibers due to fly generation during the spinning process.

Accordingly, when polymerizing polypropylene resin, the present inventors used a metallocene-based compound of a specific chemical formula that exhibits high hydrogen reactivity and adjusted the amount of hydrogen input to a specific range, thereby polymerizing polypropylene with high fluidity and increased particle size. It was confirmed that it was possible. In particular, when manufacturing fiber using a resin that satisfies a specific physical property range, the viscosity rises rapidly when the temperature is relatively high between the die to colletor distance between the extrusion die and the collector in the spinning process. The present invention was completed by confirming that the FLY phenomenon of fibers caused by high-pressure air during the process was significantly reduced, and by deriving specific crystallization behavior parameters related to complex viscosity according to temperature reduction.

When using this to manufacture fibers, the generation of FLY during the spinning process is significantly reduced, making fine fibers easier, and at the same time, productivity is significantly improved.

In the present invention, “powder” or “powder-type” refers to small particles or pieces formed without an extrusion process for raw materials, such as spherical, flat, scale, polygon, or rod shapes. Includes all forms classified as powder in the relevant technical field. The size is not particularly limited and is appropriately determined depending on the use and form, but usually has a small average particle size of about 1 mm. In addition, pellets formed through an extrusion process of raw materials and powders manufactured without an extrusion process can be distinguished based on bulk density or average diameter. In the relevant technical field, for pellets, the average particle diameter (or diameter) is 2 mm or more, or 3 mm or more, 200 mm or less, or 100 mm or less, or 5 mm or less, and the bulk density is 0.6 g / ml or less. Specifically, considering that it is defined as 0.35 g/ml to 0.6 g/ml, in the present invention, the average particle diameter (or diameter) is less than 2 mm, more specifically, the average particle diameter (or diameter) is 1.5 mm or less, or Anything less than 1 mm and more than 0 mm is defined as powder. At this time, “particle size or diameter” is the longest arbitrary straight line distance on the outer peripheral surface of the powder, and can be measured using a video microscope, etc.

In the present invention, “ultra-fine fiber” refers to a fiber of about 2.0 ㎛ or less (preferably about 1.3 ㎛ or less, about 1.0 ㎛ or less), which can mean that it is easy to apply to sound absorbing materials, etc. In addition, spinning stability refers to the fact that FLY (floating resin) or NEP (small clumps of fiber) are not created due to the high temperature or high pressure of the air used in the spinning process, and the overall meltblown web shape and fiber diameter are uniform. It can mean. In addition, fiber processability may mean that fibers with finer fibers and higher strength can be produced by enabling stretching at a high magnification due to uniform molecular weight distribution when performing a stretching process during processing.

polypropylene resin

The polypropylene resin according to one embodiment of the invention includes a homopolypropylene polymer and satisfies the following conditions i) to iii):

i) the average particle diameter is 1,200 ㎛ to 2,500 ㎛,

ii) a melt index of 1,700 g/10 min to 3,500 g/10 min measured at 230° C. with a load of 2.16 kg according to ASTM D1238;

iii) The crystallization on set temperature (T ₁ ) is 127°C or higher.

The polypropylene resin has a powder form and can achieve excellent spinning stability by satisfying an average particle diameter (D50) of about 1,200 ㎛ to 2,500 ㎛, and at the same time satisfies a high melt index and a specific crystallization on set temperature to be used in the spinning process. It exhibits unique crystallization behavior. Accordingly, it is suitable for realizing ultra-fine fibers without the FLY phenomenon, and fiber processability is also excellent.

The particle diameter of the polypropylene resin represents the average particle diameter (D50) of the longest diameter of each particle, and the average particle diameter (D50) means the particle size or particle diameter at 50% of the cumulative distribution of the number of particles according to particle size. .

The particle size of the polypropylene resin is measured using an optical diffraction particle size analyzer (HELOS, Symatec). Specifically, after injecting the sample into the hopper of the optical diffraction particle size analyzer, the particle size is in the range of 18㎛ to 3,500㎛. The distribution was measured, and the average particle size (D50) was calculated using the results.

If the average particle diameter of the polypropylene resin is outside the above range, there is a problem in that it is difficult to implement ultrafine fibers. Preferably, the average particle diameter is about 1,500 μm to 2,500 μm, about 1,500 μm to 2,300 μm, about 1,800 μm to 2,300 μm, or 1,800 μm to 2,500 μm, or 2,000 μm to 2,500 μm. or may be 2,000 ㎛ to 2,300 ㎛ there is. Within the above range, ultrafine fineness, spinning stability, and fiber processability can be further improved.

The polypropylene resin exhibits high fluidity with a melt index (MI) of 1,700 g/10min to 3,500 g/10min measured under a load of 2.16 kg at 230°C according to ASTM D1238.

When using a high-flowability resin with a melt index of about 1,800 g/10min among commercially available products, the FLY phenomenon inevitably occurred during the spinning process, making it difficult to achieve ultrafine fibers. However, the resin of the present invention has a high melt index of 1,700 g/10min to 3,500 g/10min, and at the same time satisfies a specific average particle size and crystallization on set temperature, showing a unique crystallization behavior in the spinning process. Accordingly, it is suitable for implementing ultrafine fibers without the FLY phenomenon.

The melt index (MI) is measured under a load of 2.16 kg at 230 ℃ according to the American Society for Testing and Materials (ASTM) standard ASTM D1238, and the melt index is usually the amount of hydrogen introduced during the polymerization process. It can be adjusted through control, and when using a conventional Ziegler-Natta catalyst, a high content of hydrogen must be added in the polymerization step. However, the present invention has high hydrogen reactivity, exhibits excellent catalytic activity even with a reduced amount of hydrogen input, and can produce low molecular weight polymers due to steric hindrance by the substituent bonded to the ligand, specifically the isopropyl group, as described below. By controlling the amount of hydrogen to a specific range with the metallocene-based compound of Formula 1, a homopolypropylene polymer with high fluidity and relatively large size can be produced, and is therefore suitable for implementing ultrafine fibers.

If the melt index of the polypropylene resin is less than 1,700 g/10min, the average diameter of the fibers increases, making it difficult to finesse, and if it exceeds 3,500 g/10min, spinning stability is reduced. Preferably, the melt index may be 1,800 g/10min to 3,400 g/10min, or 2,000 g/10min to 3,400 g/10min, or 2,200 g/10min to 3,350 g/10min. Within the above range, ultrafine fineness, spinning stability, and fiber processability can be further improved.

The polypropylene resin has a crystallization on set temperature (T ₁ ) of 127°C or higher. The crystallization on set temperature (T ₁ ) refers to the initial temperature at the point where the viscosity change ratio expressed by Equation 1 below is 190 or more, which is the initial temperature in the section where the viscosity increases rapidly as the temperature decreases after melting. :

[Equation 1]

Viscosity change rate = V ₂ (T ₂ ) / V ₁ (T ₁ )

In the formula, V ₁ (T ₁ ) and V ₂ (T ₂ ) are the shear rate of polypropylene resin 1 s ^-1 Below, the complex viscosity (Pa·s) measured at temperatures T ₁ and T ₂ while decreasing temperature from 180 ℃ at a rate of 1 ℃/min,

T ₁ is the crystallization on set temperature,

T ₂ is a temperature 3°C lower than the crystallization on set temperature (T ₁ ).

Specifically, the crystallization on set temperature (T ₁ ) refers to the initial temperature at a point where the viscosity increases rapidly within the die to colletor distance between the extrusion die and the collector in the spinning process of manufacturing polypropylene resin into fiber. As described above, the present invention can significantly reduce the FLY phenomenon in the spinning process by rapidly increasing the viscosity at a relatively high temperature of 127°C or higher, thereby making it easy to manufacture fine fibers.

The viscosity change rate calculated according to Equation 1 above is the polypropylene resin at a constant shear rate of 1 s ^-1 This is a crystallization behavior parameter derived by measuring the complex viscosity at that temperature while decreasing the temperature from 180°C at a rate of 1°C/min under the following conditions.

In the present invention, the complex viscosity is measured using ARES (advanced rheometric expansion system).

The viscosity change ratio parameter in Equation 1 is an indicator of the degree of change in the complex viscosity of the resin in the DCD (die to colletor distance, spinning distance) section in the spinning process when manufacturing fibers. Here, V ₁ (T ₁ ) is the complex viscosity measured at the crystallization on set temperature (T ₁ ), and V ₂ (T ₂ ) is the complex viscosity measured at a temperature (T 2 ) 3°C lower than the crystallization on set temperature (T _{1 )} . This is the measured complex viscosity. In addition, the fact that the viscosity change ratio is 190 or more means that the composite viscosity significantly increases to about 190 times in a difference of about 3 ° C. under temperature reduction conditions.

If the crystallization on set temperature (T ₁ ) of the polypropylene resin is less than 127°C and the process conditions are severely adjusted (pressure rise, temperature rise) to realize ultrafine fines, FLY or NEP ( There is a problem of small clumps of fiber occurring. Preferably, the crystallization on set temperature (T ₁ ) of the polypropylene resin may be 127°C to 130°C or 128°C to 130°C. Within the above range, the realization of ultrafine fibers, spinning stability, and fiber processability can be further improved. On the other hand, if the crystallization on set temperature (T ₁ ) is 130°C or higher, ultrafine fine formation may be difficult due to rapid solidification.

On the other hand, the viscosity V' ₁ (T ₁ ) measured at the crystallization on set temperature (T ₁ ) derived according to Equation 1 above is the viscosity V' ₂ measured at a temperature 3°C lower than the crystallization on set temperature (T ₁ ). Viscosity change rate of (T ₁ ) (=V' ₂ (T ₂ ) / V' ₁ (T ₁ )) is 220 to 450. Within the above range, the realization of ultrafine fibers, spinning stability, and fiber processability can be further improved.

In Equation 1, the complex viscosity V ₂ (T ₂ ) measured at a temperature (T ₂ ) 3°C lower than the crystallization on set temperature (T ₁ ) may be 8,300 Pa·s to 20,000 Pa·s, Within this range, the realization of ultrafine fibers, spinning stability, and fiber processability can be further improved.

The crystallization on set temperature of the polypropylene resin is 127°C or higher, and at temperatures below 127°C under reduced temperature conditions, crystallization proceeds and the viscosity rapidly increases. Accordingly, the polypropylene resin may have a complex viscosity measured at 126°C of 500 Pa·s or more. Additionally, the complex viscosity measured at 125°C may be 8,000 Pa·s or more.

The polypropylene resin may have a high melting point (Tm) of 155°C or higher. By having such a high melting point, it can have high stereoregularity and, as a result, can exhibit excellent heat resistance. If the melting point is less than 155°C, heat resistance is reduced and there is a risk of decomposition due to heat when processing the fiber at high temperatures. More specifically, the melting point of the homopolypropylene resin is 156 ℃ or higher, and considering excellent thermal stability along with sufficient processability required for injection molding and fiber processing, the melting point may be 170 ℃ or lower, or 160 ℃ or lower. .

Meanwhile, the melting point is obtained by increasing the temperature of the resin to 200 ℃, maintaining it at that temperature for 5 minutes, then lowering it to 30 ℃, and then increasing the temperature again to obtain the DSC (Differential Scanning Calorimeter, manufactured by TA) curve. It can be measured by using the peak as the melting point. At this time, the speed of temperature increase and decrease is 10 ℃/min, respectively, and the melting point is the result of measurement in the second temperature increase section.

The polypropylene resin may exhibit a molecular weight distribution (MWD) of 2.2 to 2.4. By having such a narrow molecular weight distribution, it exhibits excellent spinning stability and excellent fiber processability, enabling fine fiberization.

Meanwhile, the molecular weight distribution (MWD) is calculated by measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polypropylene polymer using gel permeation chromatography (GPC), respectively, and then calculating the weight average molecular weight relative to the number average molecular weight. The molecular weight distribution can be determined by calculating the ratio (Mw/Mn). Specifically, the gel permeation chromatography (GPC) device can be measured using a Waters PL-GPC220 device and a Polymer Laboratories PLgel MIX-B 300 mm long column. At this time, the measurement temperature was 160°C, 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was 1 mL/min. In addition, the resin samples are prepared at a concentration of 10 mg/10 mL and then supplied in an amount of 200 μL. The values of Mw and Mn can be derived using a calibration curve formed using a polystyrene standard specimen. At this time, the polystyrene standard specimen has a weight average molecular weight of 2,000 g/mol / 10,000 g/mol / 30,000 g/mol / 70,000 g/mol / 200,000 g/mol / 700,000 g/mol / 2,000,000 g/mol / 4,000,000 g/mol / Nine types of 10,000,000 g/mol were used.

The polypropylene resin according to one embodiment of the invention may be mixed with other additives within a range that does not affect the desired physical properties, and specifically, may be used mixed with antioxidants, etc.

The antioxidant is an ingredient added to prevent changes in physical properties due to heat, shear stress, etc. applied during the processing of the resin. In the process of processing polyethylene resin into fiber, chain breakage or cross-linking reactions within the resin may occur due to thermal decomposition by a radical mechanism due to heat, shear stress, etc., and as a result, there is a possibility that the physical properties of the resin, such as a decrease in viscosity, may change. There is, and the antioxidant is used to prevent such changes in physical properties.

As the antioxidant, octadecyl-3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate (octadecyl-3-[3,5-di-tert-butyl-4-hydroxyphenyl ]propionate), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H )-Trione (1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)- trione), and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H ,5H)-trione (1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethyl benzyl)-1,3,5-triazine-2,4,6-(1H, 3H, 5H)-trione), etc., and any one or a mixture of two or more of these may be used. In addition, commercially available Irganox ^® 3114 (manufactured by BASF) and Irganox ^® 1076, 1010, 3114 (manufactured by BASF) that meet the above-mentioned structural characteristics. Alternatively, Cyanox ^® 1790 (manufactured by CYTEC) may be used.

The antioxidant may be included in an amount of 0.1 to 3.0 parts by weight based on 100 parts by weight of polypropylene resin. If the antioxidant content is less than 0.1 parts by weight, the improvement effect due to the use of antioxidants is minimal, and if it exceeds 3.0 parts by weight, there is a risk of viscosity reduction and discoloration due to excessive antioxidants. Preferably, it may be 0.05 part by weight or more, or 1 part by weight or more.

In one embodiment of the invention, the polypropylene resin may further include one or more additives such as a neutralizer, slip agent, anti-blocking agent, UV stabilizer, and antistatic agent in addition to the above-mentioned components. The content of the additive is not particularly limited, and for example, it can be used in an amount of 500 ppm or more, or 700 ppm or more, and 2500 ppm or less, or 1500 ppm or less, based on the total weight of 100 polypropylene resins.

polypropylene fiber

In addition, according to another embodiment of the invention, a polypropylene fiber containing the polypropylene resin is provided.

As described above, the polypropylene resin includes a homopolypropylene polymer, and simultaneously satisfies i) a relatively large average particle diameter, ii) high fluidity, and iii) a specific crystallization behavior according to temperature reduction, and accordingly, the fiber During manufacturing, it exhibits excellent spinning stability and excellent fiber processability, enabling ultrafine fiber formation.

The polypropylene resin is in powder form.

The fiber according to one embodiment of the invention is manufactured through a melt-blown process using the polypropylene resin, and specifically, by using a resin that satisfies the specific physical properties described above, in the process of melting and then spinning while reducing the temperature, The viscosity rises rapidly at a relatively high temperature (crystallization on set temperature is above 127℃), and the FLY phenomenon of the fiber caused by high-pressure air within the die to colletor distance between the extrusion die and the collector is significantly reduced. do. As a result, it was confirmed that spinning stability was improved, making fine fibers easier, and fiber processability was significantly improved.

The fibers produced according to the above method have an average diameter of about 2.0 μm or less, preferably about 0.0001 μm to 2.0 μm, or about 0.01 μm to 2.0 μm, about 0.01 μm to 1.3 μm, or about 0.01 μm to 1.0 μm or less. am. Fibers made of ultrafine fibers in the above range can be applied to various fields and can be used as sound absorbing materials to achieve excellent sound absorption effects, especially in the high frequency range.

The average diameter of the fiber refers to the diameter of the cross section perpendicular to the long side of the fiber. In this case, the diameter of the fiber can be defined as the longest distance among the straight line distances connecting any two points of the fiber cross section. Specifically, about 400 fibers were sampled through scanning electron microscopy (SEM), and the arithmetic mean value of their diameters was calculated.

Method for producing polypropylene fiber

Meanwhile, according to another embodiment of the invention, a method for producing polypropylene fibers using the polypropylene resin is provided.

Below, each step will be described in detail.

(Step 1)

In the presence of a catalyst composition containing a transition metal compound represented by the following formula (1), a silica carrier, and an alkylaluminoxane-based cocatalyst, hydrogen is added in an amount of 1,000 ppm to 2,000 ppm and propylene monomer is polymerized to produce a homopolypropylene polymer. It includes preparing a polypropylene resin comprising.

The polypropylene resin satisfies the above-mentioned i) relatively large average particle diameter, ii) high fluidity, and iii) specific crystallization behavior according to temperature reduction, and in addition, all of the above-mentioned contents apply. The polypropylene resin prepared above is in powder form.

Specifically, the homopolypropylene polymer is manufactured through a polymerization process in which a catalyst composition containing the above-mentioned components and propylene monomer are brought into contact in the presence of hydrogen gas.

At this time, the hydrogen gas activates the inactive site of the metallocene catalyst and causes a chain transfer reaction to control the molecular weight. The metallocene compound of the present invention has excellent hydrogen reactivity, and therefore, by adjusting the amount of hydrogen gas used during the polymerization process to an amount of 1,000 ppm to 2,000 ppm, the above-mentioned i) relatively large average particle diameter, ii) intrinsic It is possible to form a polypropylene resin that satisfies certain crystallization behavior according to homogeneity and iii) temperature reduction.

Preferably, the hydrogen may be added in an amount of 1,200 ppm to 1,800 ppm or 1,200 ppm to 1,600 ppm. It is desirable to form a polypropylene resin that satisfies the specific physical properties described above within the above range.

The structure of the transition metal compound can be represented by the following formula 1:

[Formula 1]

In Formula 1,

X ₁ and X ₂ are each independently halogen,

R ₁ and R ₅ are each independently C _6-20 aryl substituted with C _1-20 alkyl,

R ₂ to R ₄ and R ₆ to R ₈ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 Alkoxysilyl, C _1-20 ether, C _1-20 silyl ether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,

A is carbon, silicon or germanium.

Meanwhile, in this specification, unless there is a special limitation, the following terms may be defined as follows.

Halogen may be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

The C _1-20 alkyl group may be a straight-chain, branched-chain, or cyclic alkyl group. Specifically, the C _1-20 alkyl group is a C _1-15 straight chain alkyl group; C _1-10 straight chain alkyl group; C _1-5 straight chain alkyl group; C _3-20 branched chain or cyclic alkyl group; C _3-15 branched chain or cyclic alkyl group; Or it may be a C _3-10 branched chain or cyclic alkyl group. More specifically, the alkyl group of C _1-20 is methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, It may be a neo-pentyl group or a cyclohexyl group.

The C _2-20 alkenyl group may be a straight chain, branched chain, or cyclic alkenyl group. Specifically, the C _2-20 alkenyl group is C _2-20 straight chain alkenyl group, C _2-10 straight chain alkenyl group, C _2-5 straight chain alkenyl group, C _3-20 branched chain alkenyl group, C _3-15 branched chain alkenyl group. It may be a nyl group, a C _3-10 branched chain alkenyl group, a C _5-20 cyclic alkenyl group, or a C _5-10 cyclic alkenyl group. More specifically, the C _2-20 alkenyl group may be an ethenyl group, propenyl group, butenyl group, pentenyl group, or cyclohexenyl group.

C _6-30 Aryl can refer to a monocyclic, bicyclic or tricyclic aromatic hydrocarbon. Specifically, C _6-30 aryl may be a phenyl group, naphthyl group, or anthracenyl group.

C _7-30 alkylaryl may refer to a substituent in which one or more hydrogens of aryl are replaced by alkyl. Specifically, C _7-30 alkylaryl may be methylphenyl, ethylphenyl, n-propylphenyl, iso-propylphenyl, n-butylphenyl, iso-butylphenyl, tert-butylphenyl, or cyclohexylphenyl.

C _7-30 Arylalkyl may refer to a substituent in which one or more hydrogens of alkyl are replaced by aryl. Specifically, C _7-30 arylalkyl may be a benzyl group, phenylpropyl, or phenylhexyl.

In the above production method, the catalyst composition includes the compound of Formula 1 as a single catalyst. Accordingly, the molecular weight distribution of the polypropylene resin produced may be narrowed compared to the conventional case of using a mixture of two or more types of catalysts.

Moreover, the compound of Formula 1 is a bridge group that connects two ligands containing an indenyl group, and contains a divalent functional group A substituted by 2 ethyl groups, thereby increasing the atomic size compared to the existing carbon bridge and increasing the available angle, thereby forming a monomer. It is easily accessible and can exhibit better catalytic activity. In addition, the two ethyl groups bonded to A can increase solubility and improve support efficiency, and when a methyl group is included as a substituent in a conventional bridge, the problem of poor support reactivity due to poor solubility when preparing a supported catalyst can be solved. .

In addition, by substituting the 2nd position of the two indenyl groups, respectively, with a methyl group and an isopropyl group, it is possible to prepare a low molecular weight polymer due to appropriate steric hindrance, and both indenyl ligands are substituted at the 4th position (R ₁ and Since R ₅ ) contains an alkyl-substituted aryl group, superior catalytic activity can be achieved through an inductive effect that can supply sufficient electrons. As a result, homo-polypropylene with high fluidity can be produced by forming the long-chain branched structure (LCB) in an appropriate ratio/distribution in the structure of homo-polypropylene.

In addition, the compound of Formula 1 contains zirconium (Zr) as a central metal, so it has more orbitals capable of accepting electrons compared to when it contains other group 14 elements such as Hf, and thus becomes a monomer with higher affinity. It can be easily combined with, and as a result, it can exhibit a superior catalytic activity improvement effect.

More specifically, in Formula 1, R ₁ and R ₅ may each independently be a C _6-12 aryl group substituted with C _1-10 alkyl, and more specifically, a C _3-6 branched group such as tert-butyl phenyl. It may be a phenyl group substituted with a chain alkyl group. In addition, the position of substitution of the alkyl group with respect to the phenyl group may be the R ₁ or R ₅ position bonded to the indenyl group and the 4th position corresponding to the para position.

Additionally, in Formula 1, R ₂ to R ₄ and R ₆ to R ₈ may each independently be hydrogen, X ₁ and X ₂ may each independently be chloro, and A may be silicon.

Representative examples of compounds represented by Formula 1 are as follows:

(1a)

The compound of Formula 1 can be synthesized by applying known reactions, and for more detailed synthesis methods, refer to the preparation examples described below.

Meanwhile, the compound of Formula 1 is used as a supported catalyst supported on a silica carrier.

When used as a supported catalyst, the particle shape and bulk density of the produced polymer are excellent, and can be suitably used in conventional slurry polymerization, bulk polymerization, and gas phase polymerization processes.

The silica carrier contains highly reactive hydroxyl groups and siloxane groups on the surface, and a carrier from which moisture is removed from the surface by drying at high temperature can be used. Specific examples of the silica carrier include silica, silica-alumina, silica-magnesia, etc., and these are usually oxides, carbonates, such as Na ₂ O, K ₂ CO ₃ , BaSO ₄ , and Mg(NO ₃ ) ₂ . It may further contain sulfate and nitrate components. When using a silica carrier, since the functional group of the metallocene compound is chemically bonded and supported, there is almost no catalyst released from the surface of the carrier during the propylene polymerization process, and as a result, polypropylene resin can be produced by slurry or vapor phase polymerization. Fouling that occurs on the reactor wall or between polymer particles can be minimized.

When the compound of Formula 1 is supported on a silica carrier, the compound of Formula 1 may be supported in an amount of 40 μmol or more, or 80 μmol or more, and 240 μmol or less, or 160 μmol or less, based on 1 g of silica. . When supported in the above content range, it exhibits appropriate supported catalyst activity, which can be advantageous in terms of maintaining the activity of the catalyst and economic efficiency.

In addition, the catalyst composition may additionally include a cocatalyst to improve high activity and process stability.

The alkylaluminoxane-based cocatalyst may include at least one selected from the group consisting of a compound represented by the following Chemical Formula 2, a compound represented by the Chemical Formula 3, and a compound represented by the Chemical Formula 4:

[Formula 2]

-[Al(R ₁₁ )-O] _m -

In Formula 2,

R ₁₁ are the same as or different from each other, and are each independently halogen; C _1-20 hydrocarbons; or a C _1-20 hydrocarbon substituted with halogen;

m is an integer of 2 or more;

[Formula 3]

J( _R12 ) ₃

In Formula 3 above,

R ₁₂ are the same as or different from each other, and are each independently halogen; C _1-20 hydrocarbons; or a C _1-20 hydrocarbon substituted with halogen;

J is aluminum or boron;

[Formula 4]

[EH] ⁺ [ZD ₄ ] ^- or [E] ⁺ [ZD ₄ ] ^-

In Formula 4 above,

E is a neutral or cationic Lewis base;

H is a hydrogen atom;

Z is a group 13 element;

D are the same or different from each other, and each independently represents a C _6-20 aryl group or a C 1-20 alkyl group in _which one or more hydrogen atoms are substituted or unsubstituted with halogen, C _1-20 hydrocarbon, alkoxy, or phenoxy am.

Examples of the compound represented by Formula 2 include alkylaluminoxane-based compounds such as methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, or butylaluminoxane, and any one or a mixture of two or more of these may be used. .

In addition, examples of compounds represented by Formula 3 include trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tripropyl aluminum, tributyl aluminum, dimethyl chloroaluminum, triisopropyl aluminum, tri-s-butyl aluminum, and tricyclo Pentyl aluminum, tripentyl aluminum, triisopentyl aluminum, trihexyl aluminum, trioctyl aluminum, ethyldimethyl aluminum, methyldiethyl aluminum, triphenyl aluminum, tri-p-tolyl aluminum, dimethyl aluminum methoxide, dimethyl aluminum ethoxide. , trimethyl boron, triethyl boron, triisobutyl boron, tripropyl boron, or tributyl boron, and any one or a mixture of two or more of these may be used.

In addition, examples of compounds represented by Formula 4 include triethylammonium tetraphenylboron, tributylammonium tetraphenylboron, trimethylammonium tetraphenylboron, tripropylammonium tetraphenylboron, and trimethylammonium tetra (p- Tolyl) boron, trimethylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, trimethylammonium tetra(p-trifluoromethylphenyl)boron, tributylammony Um tetrapenta fluorophenyl boron, N,N-diethylanilinium tetraphenyl boron, N,N-diethylanilinium tetrapenta fluorophenyl boron, diethylammonium tetrapenta fluorophenyl boron, triphenyl Phosphonium tetraphenyl boron, trimethylphosphonium tetraphenyl boron, triethylammonium tetraphenylaluminum, tributylammonium tetraphenylaluminum, trimethylammonium tetraphenylaluminum, tripropylammonium tetraphenylaluminum, trimethylammonium tetra(p -Tolyl) aluminum, tripropylammonium tetra(p-tolyl) aluminum, triethylammonium tetra(o,p-dimethylphenyl) aluminum, tributylammonium tetra(p-trifluoromethylphenyl) aluminum, trimethylammonium Tetra(p-Trifluoromethylphenyl) Aluminum, Tributylammonium Tetrapentafluorophenyl Aluminum, N,N-Diethylanilinium Tetraphenyl Aluminum, N,N-Diethylanilinium Tetrapentafluorophenyl Aluminum , diethylammonium tetrapentatetetraphenyl aluminum, triphenylphosphonium tetraphenylaluminum, trimethylphosphonium tetraphenylaluminum, tripropylammonium tetra(p-tolyl)boron, triethylammonium tetra(o,p-dimethylphenyl) ) boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, triphenylcarbonium tetra(p-trifluoromethylphenyl)boron, or triphenylcarboniumtetrapentafluorophenylboron. Any one or a mixture of two or more of these may be used.

Among the above compounds, the cocatalyst may be, more specifically, an alkylaluminoxane-based cocatalyst such as methylaluminoxane.

The alkylaluminoxane-based cocatalyst stabilizes the transition metal compound of Formula 1 and acts as a Lewis acid, combining the functional group introduced into the bridge group of the transition metal compound of Formula 1 and the Lewis acid-base. Catalytic activity can be further improved by including a metal element that can form a bond through interaction.

Additionally, the amount of the cocatalyst used can be appropriately adjusted depending on the physical properties or effects of the desired catalyst and resin composition. For example, when silica is used as the carrier, the cocatalyst may be supported in an amount of 8 mmol or more, or 10 mmol or more, and 25 mmol or less, or 20 mmol or less per weight of the carrier, for example, based on 1 g of silica. there is.

The catalyst composition having the above-described structure can be prepared by a production method comprising the step of supporting a cocatalyst compound on a carrier, and the step of supporting a transition metal compound represented by Formula 1 on the carrier, wherein the crude The loading order of the catalyst and the transition metal compound represented by Formula 1 can be changed as needed. Considering the effect of the supported catalyst with a structure determined according to the supporting order, supporting the transition metal compound after supporting the cocatalyst on the carrier makes it possible for the prepared supported catalyst to have high catalytic activity and superior performance in the polypropylene manufacturing process. Process stability can be achieved.

In addition, the above-mentioned catalyst composition may be used for polymerization as such, or may be used in a prepolymerized state through contact with a propylene monomer before use in the polymerization reaction. In this case, the production method according to one embodiment of the invention may further include the step of pre-polymerizing (or pre-polymerizing) the catalyst composition by contacting it with a propylene monomer before producing homo polypropylene through a polymerization reaction.

Typically, when using a highly active supported catalyst, polymerization occurs first on the surface of the carrier, and the resulting polymer crystallizes, inhibiting diffusion of the next monomer to form a hollow polymer, resulting in a decrease in apparent density. There is. In contrast, in the present invention, by performing prepolymerization under low temperature conditions, the diffusion rate of the monomer into the carrier can be controlled, and as a result, the morphology of the polymer can be easily controlled and improved.

In addition, the polymerization reaction of the homo polypropylene polymer may be performed as a continuous polymerization process, for example, various polymerization processes known as the polymerization reaction of olefin monomers, such as a solution polymerization process, slurry polymerization process, suspension polymerization process, or emulsion polymerization process. can be employed. In particular, in order to achieve narrow molecular weight distribution and high fluidity in the polypropylene resin produced, and considering commercial production of the product, a continuous bulk slurry polymerization process in which catalyst, propylene monomer, and optionally hydrogen gas are continuously introduced is used. can be hired. For example, the present invention can be performed through the Spheripol process using a loop reactor.

In addition, the polymerization reaction is performed at a temperature of 40 ℃ or higher, or 6 0 ℃ or higher, or 70 ℃ or lower, and a temperature of 110 ℃ or lower or 100 ℃ or lower, and 1 kgf/cm ² or higher, or 5 kgf/cm ² or higher, and 100 kgf. It can be carried out under a pressure of less than /cm ² , or less than 50 kgf/cm ² . Polymerization proceeds under such temperature and pressure, and the desired high fluidity homo polypropylene can be produced in high yield.

Additionally, in the polymerization reaction, the catalyst composition may be used in the form of a mud catalyst mixed with a mixture of oil and grease. In this case, the catalyst composition for conventional propylene polymerization is an aliphatic hydrocarbon solvent having 5 to 12 carbon atoms, such as pentane, hexane, heptane, nonane, decane, and isomers thereof, and an aromatic hydrocarbon solvent such as toluene and benzene, dichloromethane, and chlorobenzene. Since the amount of volatile organic compounds contained in the manufactured resin is significantly reduced compared to the case where it is used in a diluted or dissolved state in a hydrocarbon solvent substituted with a chlorine atom, such as, the odor resulting therefrom can also be reduced.

The polypropylene resin containing the homopolypropylene polymer manufactured through the polymerization process as described above has a large particle size, high fluidity, high crystallization on set temperature, and It exhibits a narrow molecular weight distribution.

The polypropylene resin containing the homopolypropylene polymer prepared in step 1 may be mixed with an antioxidant. As described above, when used in combination with an antioxidant, it is preferable to prevent changes in physical properties due to heat, shear stress, etc. applied during processing into fiber.

At this time, the type and content of the antioxidant are the same as described above. Additionally, optionally, as described above, one or more additives such as a neutralizer, slip agent, anti-blocking agent, UV stabilizer, and antistatic agent may be further included.

(Step 2)

Next, the polypropylene resin prepared in step 1 is manufactured into fiber by performing a melt blowing process.

Specifically, the step of producing a fiber is performed by melt spinning while injecting air at a temperature of 240°C to 270°C at a pressure of 1.8 psi to 2.3 psi into the polypropylene resin.

When manufacturing fiber using the melt blowing process, high temperature and high pressure air is injected into the melt-spun polypropylene composition. At this time, the high temperature and high pressure process injected causes stretching and opening of the fiber being spun, and die and Fineness is achieved by adjusting the distance between collectors (DCD).

In the present invention, it is possible to manufacture thin and uniform fibers by controlling the temperature and pressure of the incoming air along with the unique physical properties of polypropylene polymer, and it is possible to produce fibers with a thin and uniform thickness during the melt blowing process. It can suppress the occurrence of (small clumps of fiber).

On the other hand, when the temperature of the injected air is less than 240°C or the pressure is less than 1.8 psi, the fineness of the manufactured fiber increases and the pore size within the fiber increases, making it difficult to obtain a sufficient sound absorption effect. Additionally, when the air temperature exceeds 270°C or the pressure exceeds 2.3 psi, spinning stability decreases and FYL generation increases, making it difficult to manufacture into fiber. Conventionally, when using a resin with only a high melt index, there was a problem that it was difficult to form ultrafine fibers or the FLY phenomenon inevitably occurred when the spinning process was performed in the above-mentioned temperature and pressure range. However, it is possible to use a resin that satisfies the specific physical properties described above. In this case, it is desirable because this problem does not occur even if hot air at high temperature and high pressure is used.

In the spinning process, the die to colletor distance between the extrusion die and the collector is not particularly limited, but may be, for example, 20 cm to 60 cm. By controlling within the above range, the fineness of the fiber can be further improved. If the DCD is shorter than 20 cm, the fineness becomes thicker, and if it exceeds 60 cm, there is a risk that spinning stability will decrease and the occurrence of flies may increase.

The fibers produced according to the above method have an average diameter of about 2.0 μm or less, preferably about 1.3 μm or less, and more preferably about 1.0 μm or less. Fibers made of ultrafine fibers in the above range can be applied to various fields and can be used as sound absorbing materials to achieve excellent sound absorption effects, especially in the high frequency range.

Below, preferred embodiments are presented to aid understanding of the present invention. However, the following examples are only for illustrating the present invention, and the content of the present invention is not limited by the following examples.

Preparation Example 1: Preparation of catalyst

After weighing 3g of silica in advance in a shrink flask, 52mmol of methylaluminoxane (MAO) was added and reacted at 90°C for 24 hours. After precipitation, the upper layer was removed and washed twice with toluene. 240 μmol of transition metal compound (1a) having the following structure was dissolved in toluene and added to the reactor, and then reacted at 70°C for 5 hours. After completion of the reaction and precipitation, the upper solution was removed and the remaining reaction product was washed with toluene, then washed again with hexane and dried in vacuum to obtain 5 g of a silica-supported metallocene catalyst in the form of solid particles.

(1a)

Example 1: Preparation of polypropylene resin comprising homopolypropylene polymer

In the presence of the silica-supported metallocene catalyst prepared in Preparation Example 1, bulk-slurry polymerization of propylene was performed using two consecutive loop reactors. At this time, 60 g/h of triethylaluminum (TEAL) was injected using a pump, hydrogen gas was injected at 1,200 ppm using a pump, and the supported catalyst prepared above was 16% by weight in mud mixed with oil and grease. It was used in catalyst form. Homopolypropylene polymer was manufactured while maintaining the temperature of the reactor at 70°C and the amount of sand per hour being maintained at 40 kg.

A polypropylene resin was prepared by mixing 0.10 parts by weight of Irganox 1076 ^® (manufactured by BASF) as a phenolic antioxidant with 100 parts by weight of the homopolypropylene polymer prepared above.

Example 2

Polypropylene resin was prepared in the same manner as Example 1, except that the hydrogen input amount was changed to 1,400 ppm.

Example 3

Polypropylene resin was prepared in the same manner as Example 1, except that the hydrogen input amount was changed to 1,600 ppm.

Comparative Example 1

A polypropylene resin was prepared by using Basel MF650Y powder-type polypropylene resin (MI 1800) and mixing 0.10 parts by weight of Irganox 1076 ^® (manufactured by BASF) as a phenol-based antioxidant with 100 parts by weight of the resin.

Comparative Example 2

A polypropylene resin was prepared by using Basel MF650Z powder-type polypropylene resin (MI 2300) and mixing 0.10 parts by weight of Irganox 1076 ^® (manufactured by BASF) as a phenolic antioxidant with 100 parts by weight of the resin.

Experimental Example 1: Evaluation of physical properties of polypropylene resin

The physical properties of the polypropylene resin (the resin is in powder form) used in the above examples and comparative examples were measured, and the results are shown in Table 2 below.

(1) Average particle diameter (D50): After injecting the sample of the polypropylene resin prepared in Examples and Comparative Examples into the hopper of an optical diffraction particle size analyzer (HELOS, Symatec), particle size distribution in the range of 18㎛ to 3,500㎛ was measured, and the average particle size (D50) was calculated using the results. D50 is the particle size of the resin at the 50% point of the cumulative distribution of the number of particles according to the particle size of the resin.

(2) Melt index (MI, 2.16 kg) (g/10min): Samples of polypropylene resin prepared in Examples and Comparative Examples were measured at 230°C with a load of 2.16 kg according to ASTM D1238, and were melted for 10 minutes. It is expressed as the weight (g) of the resin produced.

(3) Crystallization on set temperature (T ₁ ): Samples of polypropylene resin prepared in Examples and Comparative Examples were subjected to shear rate of 1 s ^-1 The complex viscosity (Pa·s) was measured while decreasing the temperature from 180°C to 1°C/min, and the viscosity values at that temperature are listed in Table 1. Based on the results in Table 1, the crystallization on set temperature (T ₁ ), which is the initial temperature at the point where the viscosity change rate is 190, was derived according to Equation 1 below.

Complex viscosity was obtained by dynamic frequency sweep at 190°C using ARES (advanced rheometric expansion system). The dynamic frequency sweep was measured using a disk-shaped 25 mm parallel plate.

[Equation 1]

Viscosity change rate = V ₂ (T ₂ ) / V ₁ (T ₁ )

V ₁ (T ₁ ) is the complex viscosity measured at the crystallization on set temperature (T ₁ ),

V ₂ (T ₂ ) is the complex viscosity measured at a temperature (T ₂ ) 3°C lower than the crystallization on set temperature (T ₁ ).

(4) Melting temperature (Tm) (°C): The temperature of the sample of the polypropylene resin prepared in Examples and Comparative Examples was increased to 200°C, maintained at that temperature for 5 minutes, and then lowered to 30°C. , the temperature was increased again and the top of the DSC (Differential Scanning Calorimeter, manufactured by TA) curve was taken as the melting temperature. At this time, the rate of temperature rise and fall was 10°C/min, and the melting temperature was measured in the second temperature rising section.

(5) Molecular weight distribution (MWD): Samples of the polypropylene resin prepared in Examples and Comparative Examples were measured using gel permeation chromatography (GPC) to determine the weight average molecular weight (Mw) and number average molecular weight ( Mn) was measured, and the molecular weight distribution (MDW, i.e., Mw/Mn) was calculated by dividing the measured weight average molecular weight by the number average molecular weight.

Specifically, a Waters PL-GPC220 instrument was used as a gel permeation chromatography (GPC) device, and a Polymer Laboratories PLgel MIX-B 300 mm long column was used. At this time, the measurement temperature was 160°C, 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was 1 mL/min. Samples of polypropylene resin according to Examples and Comparative Examples were each prepared at a concentration of 10 mg/10 mL and then supplied in an amount of 200 μL. The values of Mw and Mn were derived using a calibration curve formed using a polystyrene standard specimen. The weight average molecular weight of the polystyrene standard specimen is 2,000 g/mol / 10,000 g/mol / 30,000 g/mol / 70,000 g/mol / 200,000 g/mol / 700,000 g/mol / 2,000,000 g/mol / 4,000,000 g/mol / 10,000,000 g Nine types of /mol were used.

viscosity
(Paㆍs) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 180℃ 16.12 11.05 5.73 15.72 10.65 150℃ 29.18 19.78 10.19 28.76 19.06 132℃ 46.37 30.89 14.95 44.05 29.91 131℃ 48.15 32.03 15.92 46.11 30.46 130℃ 50.87 33.42 16.41 47.80 31.55 129℃ 58.15 35.37 17.69 50.00 33.07 128℃ 79.87 38.92 19.14 52.59 35.42 127℃ 380.16 84.13 44.35 56.04 37.82 126℃ 13484.8 1068.89 534.45 62.70 40.82 125℃ 17997.2 14789.90 8490.22 136.37 85.59 124℃ - - - 9780.85 6174.55 123℃ - - - 12733.5 8038.5

division Average particle diameter (㎛) MI (g/min) Tm(℃) T ₁ (℃) Viscosity change rate MWD Experimental Example 1-1 Example 1 1,550 1790 156 129 231.9 2.22 Experimental Example 1-2 Example 2 1,620 2280 156 128 380.0 2.22 Experimental Example 1-3 Example 3 1,760 3316 156 128 443.6 2.22 Comparative Experiment Example 1-1 Comparative Example 1 1,052 1850 154 126 203.1 2.19 Comparative Experiment Example 1-2 Comparative Example 2 1,112 2310 154 126 196.9 2.19

Through the viscosity change data in Table 1 above, the crystallization on set temperature (T ₁ ) of the polypropylene resin was derived.

Referring to Table 2 above, it was confirmed that the polypropylene resin of the present invention has a high melt index and melting point, a larger average particle diameter, and a higher crystallization on set temperature than commercially available polymers with an equivalent melt index.

Experimental Example 2: Evaluation of fiber spinning stability

For the polypropylene resin prepared according to the above examples and comparative examples, polypropylene fibers were manufactured under different spinning process conditions as shown in Table 3, and the physical properties were measured, and the results are shown in Table 3 below.

Figure 1 is a schematic diagram showing the meltblown spinning process.

<Radiation conditions>

See Bresee, R.R. and Qureshi, U.A. “Influence of Processing Conditions on Melt Blown Web Structure. The resin was extruded into a microfiber web by a process similar to that described in Part 1-DCD, “international Nonwovens Journal, 12(1) 49-55 (2004)].

Specifically, the resin composition is supplied to a melt pump (65 rpm) using a twin screw extruder and then supplied to a melt blowing die (width of rotating drum collector: 650 cm) with an outlet (30 holes/inch) and an outlet diameter of 0.3 pi. With one exception, see Bresee, R.R. and Qureshi, U.A. “Influence of Processing conditions on Melt Blown Web Structure. It was extruded into a microfiber web by a process similar to that described in “Part 1-DCD,” International Nonwovens Journal, 13(1) 49-55 (2004).

Hot Air Pressure(psi): 1.8 / 2.3

Hot Air Temperature(℃) : 240 / 270

DCD(Die to Collector Distance, cm): 20 / 30 / 60

Nonwoven Weight (gsm): 20

(1) Fiber average diameter

For the fiber manufactured in Experimental Example 2, the diameter of 400 samples was measured using FESEM (HITACHI S-4800), the average diameter of the fiber was confirmed from the average value of the measured values, and the results are shown in Table 3. It was described. For reference, it refers to the diameter of the cross-section perpendicular to the long side of the fiber. In this case, the diameter of the fiber may be defined as the longest straight line distance connecting any two points on the fiber cross-section.

(2) Radiation stability

During the manufacturing process of Experimental Example 2, spinning stability was evaluated visually based on the presence or absence of FLY, lumps, and single yarns occurring according to the following criteria.

O: FLY, no lumps or single yarns occur

△: Some FLY occurs

X: FLY, lump and single yarn occurrence.

division radiation conditions Fiber average diameter (㎛) radiation
stability pressure (psi) Temperature (℃) DCD(cm) Experimental Example 2-1-1 Example 1 1.8 270 30 0.91 ○ Experimental Example 2-1-2 Example 1 2.3 240 60 0.89 ○ Experimental Example 2-2-1 Example 2 1.8 240 20 0.97 ○ Experimental Example 2-2-2 Example 2 1.8 240 30 0.80 ○ Experimental Example 2-2-3 Example 2 2.3 270 60 0.74 ○ Experimental Example 2-3-1 Example 3 1.8 240 20 0.65 ○ Experimental Example 2-3-2 Example 3 1.8 240 30 0.51 ○ Experimental Example 2-3-3 Example 3 2.3 270 60 0.48 ○ Comparative Experiment Example 2-1-1 Comparative Example 1 1.8 240 20 2.32 △ Comparative Experiment Example 2-1-2 Comparative Example 1 1.8 270 30 No fiber formation X Comparative Experiment Example 2-1-3 Comparative Example 1 2.3 240 60 No fiber formation X Comparative Experiment Example 2-2-1 Comparative Example 2 1.8 240 20 No fiber formation X Comparative Experiment Example 2-2-2 Comparative Example 2 1.8 240 30 No fiber formation X Comparative Experiment Example 2-2-3 Comparative Example 2 2.3 270 60 No fiber formation X Comparative Experiment Example 2-3-1 Comparative Example 3 1.8 240 20 No fiber formation X Comparative Experiment Example 2-3-2 Comparative Example 3 1.8 240 30 No fiber formation X Comparative Experiment Example 2-3-3 Comparative Example 3 2.3 270 60 No fiber formation X

Referring to Table 3 above, the fiber manufactured using the polypropylene resin of the present application has excellent spinning stability when the spinning process is performed under the same conditions compared to a commercially available resin having an equivalent melt index, and accordingly, 1 It was confirmed that ultrafine fine fibers of less than ㎛ can be achieved.

Comparative experimental examples using commercially available high melt index resins confirmed that when high temperature and high pressure hot air was used, FLY, lumps, and single yarns were all generated, making it difficult to manufacture them into fibers.

Claims (17)

A polypropylene resin comprising a homopolypropylene polymer and satisfying the conditions i) to iv) below:
i) the average particle diameter is 1,200 ㎛ to 2,500 ㎛,
ii) a melt index of 1,700 g/10 min to 3,500 g/10 min measured at 230° C. with a load of 2.16 kg according to ASTM D1238;
iii) the crystallization on set temperature (T ₁ ) is 127°C or higher, and the crystallization on set temperature (T ₁ ) is the initial temperature at a point where the viscosity change ratio expressed by Equation 1 below is 190 or higher,
iv) the molecular weight distribution is 2.2 to 2.4,
[Equation 1]
Viscosity change rate = V ₂ (T ₂ ) / V ₁ (T ₁ )
In the formula, V ₁ (T ₁ ) and V ₂ (T ₂ ) are the shear rate of polypropylene resin 1 s ^-1 Below, the complex viscosity (Pa·s) measured at temperatures T ₁ and T ₂ while decreasing temperature from 180 ℃ at a rate of 1 ℃/min,
T ₁ is the crystallization on set temperature,
T ₂ is a temperature 3°C lower than the crystallization on set temperature (T ₁ ).
According to paragraph 1,
The viscosity V' ₁ (T _{1 )} measured at the crystallization on set temperature (T ₁ ) derived according to Equation 1 above is the viscosity V' ₂ (T ₁ ) A polypropylene resin with a viscosity change ratio of 220 to 450.
According to paragraph 1,
The crystallization on set temperature (T ₁ ) is 127 ℃ to 130 ℃, polypropylene resin.
According to paragraph 1,
The V ₂ (T ₂ ) is a polypropylene resin of 8,300 Pa·s to 20,000 Pa·s.
According to paragraph 1,
The resin is a polypropylene resin having a complex viscosity measured at 126°C of 500 Pa·s or more.
According to paragraph 1,
The resin is a polypropylene resin having a complex viscosity measured at 125°C of 8,000 Pa·s or more.
According to paragraph 1,
The resin is a polypropylene resin having a melting point of 155°C or higher.
delete According to paragraph 1,
The resin is a powdery polypropylene resin.
A polypropylene fiber comprising the polypropylene resin according to any one of claims 1 to 9.
According to clause 10,
Polypropylene fibers with an average diameter of 2.0 μm or less.
In the presence of a catalyst composition containing a transition metal compound represented by the following formula (1), a silica carrier, and an alkylaluminoxane-based cocatalyst, hydrogen is added in an amount of 1,000 ppm to 2,000 ppm and propylene monomer is polymerized to produce a homopolypropylene polymer. Preparing a polypropylene resin comprising; and
A step of producing a fiber by melt spinning while injecting air at a temperature of 240°C to 270°C into the polypropylene resin at a pressure of 1.8 psi to 2.3 psi,
A method for producing polypropylene fibers, wherein the polypropylene resin satisfies the following conditions i) to iv):
i) the average particle diameter is 1,200 ㎛ to 2,500 ㎛,
ii) a melt index of 1,700 g/10 min to 3,500 g/10 min measured at 230° C. with a load of 2.16 kg according to ASTM D1238;
iii) the crystallization on set temperature (T ₁ ) is 127°C or higher, and the crystallization on set temperature (T ₁ ) is the initial temperature at a point where the viscosity change ratio expressed by Equation 1 below is 190 or higher,
iv) the molecular weight distribution is 2.2 to 2.4,
[Equation 1]
Viscosity change rate = V ₂ (T ₂ ) / V ₁ (T ₁ )
In the formula, V ₁ (T ₁ ) and V ₂ (T ₂ ) are the shear rate of polypropylene resin 1 s ^-1 Below, the complex viscosity (Pa·s) measured at temperatures T ₁ and T ₂ while decreasing temperature from 180 ℃ at a rate of 1 ℃/min,
T ₁ is the crystallization on set temperature,
T ₂ is a temperature 3°C lower than the crystallization on set temperature (T ₁ ).
[Formula 1]

In Formula 1,
X ₁ and X ₂ are each independently halogen,
R ₁ and R ₅ are each independently C _6-20 aryl substituted with C _1-20 alkyl,
R ₂ to R ₄ and R ₆ to R ₈ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 Alkoxysilyl, C _1-20 ether, C _1-20 silyl ether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,
A is carbon, silicon, or germanium.
According to clause 12,
A is silicon,
Wherein R ₁ and R ₅ are each independently a phenyl group substituted with a C _3-6 branched chain alkyl group.
According to clause 12,
Method for producing polypropylene fiber, wherein the transition metal compound is a compound represented by the following formula 1a:
[Formula 1a]
.
According to clause 12,
A method for producing polypropylene fibers, wherein the polymerization is performed by a continuous bulk slurry polymerization process.
According to clause 12,
In the melt spinning process,
A method for producing polypropylene fibers, wherein the distance between the melt die and the collector for collecting the fibers of the melt-spun polypropylene resin is 20 cm to 60 cm.
According to clause 12,
A method of producing a polypropylene fiber, wherein the polypropylene resin is in powder form.