KR102464410B1 - Polypropylene for filament and method for preparing the same - Google Patents

Abstract

The present invention provides a polypropylene that can be used for manufacturing a filament having high strength and excellent spinning processability and a method for manufacturing the same.

Description

Polypropylene for filament and its manufacturing method

The present invention relates to a polypropylene that can be used for manufacturing a filament having high strength and excellent spinning processability and a method for manufacturing the same.

Olefin polymerization catalyst systems can be classified into Ziegler-Natta and metallocene catalyst systems, and these two high-activity catalyst systems have been developed according to their respective characteristics. Ziegler-Natta catalyst has been widely applied to existing commercial processes since its invention in the 1950s. There is a problem in that there is a limit in securing the desired physical properties because the composition distribution is not uniform.

On the other hand, the metallocene catalyst is composed of a combination of a main catalyst containing a transition metal compound as a main component and a cocatalyst containing an organometallic compound containing aluminum as a main component. Such a catalyst is a homogeneous complex catalyst and is a single site catalyst. The molecular weight distribution is narrow according to the single active point characteristic, and a polymer with a uniform composition distribution of the comonomer is obtained. It has properties that can change crystallinity, etc.

In the case of polypropylene resins, which are usually used mainly for manufacturing filaments, the strength of the filaments is determined according to the orientation and degree of crystallization of the polypropylene polymer chains. can increase

However, as the molecular weight of the homopolypropylene resin increases, the risk of single yarn during spinning due to phenomena such as melt fracture and draw resonance increases, making it difficult to secure stable processability during spinning.

In order to improve this, a narrow molecular weight distribution characteristic is required, but the homo polypropylene resin prepared with the existing Ziegler-Natta catalyst has a limit in the molecular weight distribution that can be realized, and thus it is difficult to increase the weight average molecular weight to a sufficient level.

Accordingly, there is a demand for the development of a polypropylene resin capable of improving the strength and spinning processability of the filament.

Accordingly, an object of the present invention is to provide a polypropylene that can be used for manufacturing a filament having high strength and excellent spinning workability, and a method for manufacturing the same.

According to one embodiment of the present invention, there is provided a polypropylene for filaments satisfying the following conditions i) to iii):

i) melt index (measured with 2.16 kg load at 230°C according to ASTM D1238) from 1.6 g/10 min to 9 g/10 min,

ii) molecular weight distribution less than 3.0;

iii) Residual stress ratio 0.2% or less according to the following formula 1

[Formula 1]

Residual stress ratio = (RS ₁ /RS ₀ )*100

In Equation 1, RS ₀ is the residual stress at any one time point (t ₀ ) less than 0.05 seconds after applying a strain of 200% to the polypropylene for the filament under 235 ° C., RS ₁ is the polypropylene for the filament under 235 ° C. Residual stress at any one time point (t ₁ ) between 0.05 sec and 1.50 sec after applying a strain of 200% to propylene.

According to another embodiment of the present invention, in the presence of a catalyst composition comprising a compound of Formula 1, the method for producing the polypropylene resin for filaments of claim 1, comprising the step of polymerizing a propylene monomer by adding hydrogen to provide:

[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 silylether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl;

A is carbon, silicon or germanium,

R ₉ is a C _3-10 linear alkyl group, and R ₁₀ is a C _1-2 linear alkyl group.

According to another embodiment of the present invention, there is provided a filament, more specifically, a multifilament comprising the polypropylene for the filament of the embodiment.

The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprise", "comprising" or "having" are intended to designate the presence of an embodied feature, step, component, or a combination thereof, but one or more other features or steps; It should be understood that the possibility of the presence or addition of components, or combinations thereof, is not precluded in advance.

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

Hereinafter, polypropylene for filaments and a method for manufacturing the same according to specific embodiments of the present invention will be described.

The present invention relates to the molecular weight of a homopolypropylene produced by preparing a homopolypropylene using a metallocene catalyst to be described later in order to supplement the physical properties of a filament prepared with a conventional Ziegler-Natta catalyst, more specifically, a multifilament. Since the distribution is narrow, it is possible to produce a uniform fiber with a thin thickness, and as a result, it is possible to manufacture a high-strength filament, more specifically, a multifilament.

Specifically, the homopolypropylene prepared from the characteristic metallocene catalyst of the present invention is a homogeneous single homopolypropylene with an increased stereoregularity of 99 mol% or more. A narrow molecular weight distribution can be satisfied.

As such, as the polypropylene of one embodiment has a narrow molecular weight distribution, the overall weight average molecular weight can be increased, so that the strength of the finally manufactured filament is improved, and at the same time, the residual stress is decreased as the content of the polymer chain is relatively decreased. By preventing excessive increase, stable spinning workability can be realized without deterioration of workability when the draw ratio is raised.

Specifically, the polypropylene for filaments according to an embodiment of the present invention satisfies the following conditions:

i) melt index (measured with 2.16 kg load at 230°C according to ASTM D1238) from 1.6 g/10 min to 9 g/10 min,

ii) molecular weight distribution less than 3.0;

iii) Residual stress ratio 0.2% or less.

The polypropylene may be a propylene homopolymer, or may contain other comonomers than propylene. The content of the comonomer is preferably 0.5 wt% to 5 wt% compared to the metallocene polypropylene. As the comonomer, an alpha-olefin having 2 to 10 carbon atoms other than propylene may be used, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1 and at least one selected from the group consisting of -decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and mixtures thereof. Preferably, the polypropylene may be a propylene homopolymer.

Polypropylene for filaments according to an embodiment of the present invention has a melt index (MI) of 1.6 g/10min to 9 g/10min, or 4 g/10min, measured at 230° C. under a load of 2.16 kg according to ASTM D 1238. to 8 g/10 min, or from 5 g/10 min to 7 g/10 min. The melt index can be adjusted according to the amount of hydrogen input during the polymerization process, and the polypropylene for filaments according to the present invention has an MI within the range as described above, thereby improving spinnability and strength of filaments at the same time.

In particular, in filament processing using polypropylene for filaments, if the MI is less than 1.6 g/10min, the processing pressure may increase and workability may decrease, and if it exceeds 9 g/10min, it is difficult to implement high strength in the manufactured filament . In order to produce polypropylene having an MI value in this range, when using a Ziegler-Natta catalyst, a high content of hydrogen must be input in the polymerization step, but a catalyst containing a metallocene compound as described below is used. In this case, since it is possible to input a relatively low amount of hydrogen, there is an advantage in that activity control is easy and process stability is increased.

In addition, the polypropylene for filaments according to an embodiment of the present invention has a narrow molecular weight distribution (MWD=Mw/Mn) of less than 3.0, or 1.0 to 2.9, or 2.0 to 2.9, or 2.3 to 2.5, along with the aforementioned MI. . By having such a narrow molecular weight distribution, it is possible to exhibit excellent rigidity in manufacturing the filament, and to secure stable spinning processability by relatively reducing the polymer chain content.

In addition, the polypropylene for filaments according to an embodiment of the present invention has a low residual stress ratio of 0.2% or less, together with MI and MWD as described above.

The residual stress ratio is a value measured according to Equation 1 below by performing a stress relaxation test by applying a large strain to the polypropylene for filaments to confirm fiber workability.

[Formula 1]

Residual stress ratio = (RS ₁ /RS ₀ )*100

In Equation 1, RS ₀ is the residual stress at any one time point (t ₀ ) less than 0.05 seconds after applying a strain of 200% to the polypropylene for the filament under 235 ° C., RS ₁ is the polypropylene for the filament under 235 ° C. Residual stress at any one time point (t ₁ ) between 0.05 sec and 1.50 sec after applying a strain of 200% to propylene.

When the ratio of residual stress according to Equation 1 exceeds 0.2%, fibers are usually spun in a molten state during filament manufacturing and stretched in a semi-melted state through cooling. At this time, if the residual stress is high, As the properties of the fibers are increased, the possibility of occurrence of single yarns of the fibers is increased, and as a result, there is a risk that the defective rate is increased.

In addition, in Equation 1, RS ₀ represents the residual stress immediately after applying a strain of 200% to the polypropylene for filaments under 235 _° C. And, in Equation 1, RS ₁ represents a residual stress within about 1.5 seconds after t ₀ under the same conditions as RS ₀ [eg, at any one time point (t ₁ ) between 0.05 seconds and 2.00 seconds].

Specifically, in Equation 1, t ₀ may be selected from 0.01 second, or 0.015 second, or 0.02 second, or 0.025 second, or 0.03 second, or 0.035 second, or 0.04 second, or 0.045 second. And, in Equation 1, t ₁ is 0.05 second, or 0.10 second, or 0.20 second, or 0.30 second, or 0.40 second, or 0.50 second, or 0.60 second, or 0.70 second, or 0.80 second, or 0.90 second, or 1.00 seconds, or 1.10 seconds, or 1.20 seconds, or 1.30 seconds, or 1.40 seconds, or 1.50 seconds, or 1.60 seconds, or 1.70 seconds, or 1.80 seconds, or 1.90 seconds, or 2.00 seconds. Preferably, in order to easily secure valid data when measuring the residual stress, it may be advantageous for t ₀ to be 0.02 seconds and t ₁ to be 1.00 seconds in Equation 2 above.

In addition, the residual stress ratio of the polypropylene for the filament is measured under an environment (eg, 235° C.) similar to the process conditions for performing melt spinning when manufacturing the filament. The temperature of 235° C. corresponds to a temperature suitable for melt spinning by completely dissolving the polypropylene resin for filaments or a composition thereof.

Considering the fiber processability improvement effect according to the residual stress ratio control, the residual stress ratio of the homo polypropylene is more specifically 0.005% to 0.2%, more specifically 0.02% to 0.18%, or 0.1% to 0.12%. can

The polypropylene for the filament may have a weight average molecular weight (measured by GPC) of 150,000 g/mol to 300,000 g/mol, or 150,000 g/mol to 200,000 g/mol, or 160,000 g/mol to 170,000 g/mol. As described above, as the weight average molecular weight of the polypropylene for the filament increases, a filament having high strength can be prepared. When the weight average molecular weight (measured by GPC) of the polypropylene for filaments is excessively reduced, the strength of the filaments prepared therefrom may be lowered, and the polypropylene for filaments has an excessively increased weight average molecular weight (measured by GPC), It may be difficult to realize stable spinning processability, such as the possibility of single yarns occurring during the spinning process during filament manufacturing due to melt fracture and draw resonance caused by an increase in high molecular weight.

In the present specification, the weight average molecular weight was measured using gel permeation chromatography (GPC: gel permeation chromatography, manufactured by Waters), in this case, the analysis temperature was 160 ° C., the solvent was trichlorobenzene, and polystyrene was standardized to measure the molecular weight.

In addition, the polypropylene for filaments may have a stereoregularity of 99 mol% or more, or 99 mol% to 100 mol%, or 99 mol% to 99.9 mol%. As the polypropylene for filaments according to an embodiment of the present invention has such a high degree of stereoregularity, it can exhibit excellent rigidity when manufacturing filaments.

In addition, the polypropylene for the filament may have a melting point (Tm) of 140 °C to 155 °C, or 145 °C to 155 °C, or 151 °C to 155 °C. When the Tm of the polypropylene for filaments exceeds 155° C., it is not easy to manufacture a resin, and there is a possibility that productivity may decrease. In addition, if the Tm is too low, there is a fear that the fiber may be singled out due to the decrease in spinnability.

Polypropylene for filaments according to an embodiment of the present invention having the above physical properties, in the presence of a catalyst composition comprising a compound of Formula 1 as a catalytically active component, by adding hydrogen to polymerize the propylene monomer It can be prepared by a manufacturing method comprising:

[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 silylether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl;

A is carbon, silicon or germanium,

R ₉ is a C _3-10 linear alkyl group, and R ₁₀ is a C _1-2 linear alkyl group.

Unless otherwise limited herein, the following terms may be defined as follows.

The 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 or cyclic alkyl group; C _3-15 branched or cyclic alkyl group; Or it may be a C _3-10 branched or cyclic alkyl group. More specifically, the C1-20 alkyl group is a 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, neo - It may be a pentyl group or a cyclohexyl group.

The C _2-20 alkenyl group may be a straight chain, branched chain or cyclic alkenyl group. Specifically, 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, a propenyl group, a butenyl group, a pentenyl group, or a cyclohexenyl group.

C _6-30 aryl may mean a monocyclic, bicyclic or tricyclic aromatic hydrocarbon. Specifically, C _6-30 aryl may be a phenyl group, a naphthyl group, or an anthracenyl group.

C _7-30 alkylaryl may mean a substituent in which one or more hydrogens of aryl are substituted with 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 mean a substituent in which one or more hydrogens of the alkyl are substituted by aryl. Specifically, C _7-30 arylalkyl may be a benzyl group, phenylpropyl, or phenylhexyl.

The catalyst composition used for the production of homo polypropylene according to an embodiment of the present invention includes the compound of Formula 1 as a single catalyst. Accordingly, the molecular weight distribution may be significantly narrower than that of the homo polypropylene prepared compared to the case of using a mixture of two or more catalysts in the prior art.

In addition, both of the two indenyl groups serving as ligands are substituted with a methyl group at the 2nd position, and the 4th position (R ₁ and R ₅ ) each contain an alkyl-substituted phenyl group, so that a better catalyst due to the inductive effect capable of supplying sufficient electrons activity can be shown.

In addition, since the compound of Formula 1 includes zirconium (Zr) as a central metal, it has more orbitals capable of accommodating electrons compared to when it includes other Group 14 elements such as Hf, and thus has a higher affinity As a result, it is possible to exhibit a more excellent catalytic activity improvement effect due to the characteristic that it can be easily combined with a monomer.

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 chain such as tert-butyl phenyl. It may be a phenyl group substituted with an alkyl group. In addition, the substitution position of the alkyl group with respect to the phenyl group may be the 4th position corresponding to the R ₁ or R ₅ position and the para position bonded to the indenyl group.

In addition, in Formula 1, R ₂ to R ₄ and R ₆ to R ₈ may each independently be hydrogen, and X ₁ and X ₂ may each independently be chloro.

In addition, in Formula 1, A may be silicon.

In addition, the substituent of A, R ₉ is a C _3-10 linear alkyl group, R ₁₀ may be a C _1-2 linear alkyl group, more specifically, R ₉ is a normal-propyl group, R ₁₀ is a methyl group can be By introducing two different kinds of straight-chain alkyl groups as a substituent of such a bridge, it is possible to exhibit excellent catalytic activity with excellent support reactivity.

Specifically, in R ₉ or R ₁₀ , when R ₉ and R ₁₀ are identical to each other, solubility may be poor during preparation of a supported catalyst, and thus a problem of poor supported reactivity may appear.

In addition, in the case of using an alkoxyalkyl group instead of a C _3-10 linear alkyl group or a C _1-2 linear alkyl group in R ₉ or R ₁₀ , due to a structural difference in which the catalytic reaction site becomes bulky, a relatively high Polypropylene having a melt index, a low weight average molecular weight, and a wide molecular weight distribution (MWD) is synthesized, so it is difficult to satisfy high strength and high elongation characteristics.

Representative examples of the compound represented by Formula 1 are shown in Formula 1-1 below:

[Formula 1-1]

The compound of Formula 1 may be synthesized by applying known reactions, and for a more detailed synthesis method, refer to Preparation Examples to be described later.

Meanwhile, the compound of Formula 1 may be used as a single component or may be used as a supported catalyst supported on a carrier.

As the carrier, a carrier containing a hydroxyl group on the surface may be used, and preferably one having a reactive hydroxyl group and a siloxane group, which is dried to remove moisture from the surface, may be used. For example, silica dried at high temperature, silica-alumina, and silica-magnesia may be used, and these are typically oxides, carbonates, such as Na ₂ O, K ₂ CO ₃ , BaSO ₄ , and Mg(NO ₃ ) ₂ ; It may contain sulfate, and nitrate components.

The drying temperature of the carrier is preferably 200 °C to 800 °C, more preferably 300 °C to 600 °C, and most preferably 300 °C to 400 °C. When the drying temperature of the carrier is less than 200 ℃, there is too much moisture and the surface moisture and the cocatalyst are reacted. It is undesirable because it disappears and only the siloxane remains, and the reaction site with the promoter decreases.

The amount of hydroxyl groups on the surface of the carrier is preferably 0.1 mmol/g to 10 mmol/g, more preferably 0.5 mmol/g to 5 mmol/g. The amount of hydroxyl groups on the surface of the carrier can be controlled by the method and conditions or drying conditions of the carrier, such as temperature, time, vacuum or spray drying, and the like.

If the amount of the hydroxyl group is less than 0.1 mmol/g, there are few reaction sites with the co-catalyst, and if it exceeds 10 mmol/g, it is not preferable because it may be caused by moisture other than the hydroxyl group present on the surface of the carrier particle. not.

In addition, when supported on a carrier, the mass ratio of the compound of Formula 1 to the carrier is preferably 1:1 to 1:1000. When the carrier and the compound of Formula 1 are included in the above mass ratio, an appropriate supported catalyst activity may be exhibited, which may be advantageous in terms of maintaining the activity of the catalyst and economic feasibility.

In addition, the catalyst composition may further include a co-catalyst in addition to the compound represented by Formula 1 and the carrier in terms of improving high activity and process stability. The cocatalyst may include at least one of compounds represented by the following Chemical Formula 2, Chemical Formula 3, or Chemical Formula 4.

[Formula 2]

-[Al(R ₁₁ )-O] _m -

In Formula 2,

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

m is an integer greater than or equal to 2;

[Formula 3]

J(R ₁₂ ) ₃

In Formula 3,

R ₁₂ is as defined in Formula 2 above;

J is aluminum or boron;

[Formula 4]

[EH] ⁺ [ZA ₄ ] ^- or [E] ⁺ [ZA ₄ ] ^-

In Formula 4,

E is a neutral or cationic Lewis base;

H is a hydrogen atom;

Z is a group 13 element;

A may be the same or different from each other, and each independently represents a C _6-20 aryl group or 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. .

Examples of the compound represented by Formula 2 include methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, and the like, and a more preferable compound is methylaluminoxane.

Examples of the compound represented by Formula 3 include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylchloroaluminum, triisopropylaluminum, tri-s-butylaluminum, tricyclopentylaluminum , tripentyl aluminum, triisopentyl aluminum, trihexyl aluminum, trioctyl aluminum, ethyl dimethyl aluminum, methyldiethyl aluminum, triphenyl aluminum, tri-p-tolyl aluminum, dimethyl aluminum methoxide, dimethyl aluminum ethoxide, trimethyl boron, triethylboron, triisobutylboron, tripropylboron, tributylboron and the like are included, and more preferred compounds are selected from trimethylaluminum, triethylaluminum and triisobutylaluminum.

Examples of the compound 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, tributylammonium tetra Pentafluorophenyl boron, N,N-diethylanilinium tetraphenylboron, N,N-diethylaniliniumtetrapentafluorophenylboron, diethylammonium tetrapentafluorophenylboron, triphenylphosphonium Tetraphenyl boron, trimethylphosphonium tetraphenyl boron, triethylammonium tetraphenylaluminum, tributylammonium tetraphenylaluminum, trimethylammonium tetraphenylaluminum, tripropylammoniumtetraphenylaluminum, trimethylammonium tetra(p-tolyl) ) Aluminum, tripropylammonium tetra(p-tolyl)aluminum, triethylammoniumtetra(o,p-dimethylphenyl)aluminum, tributylammonium tetra(p-trifluoromethylphenyl)aluminum, trimethylammonium tetra( p-trifluoromethylphenyl)aluminum, tributylammonium tetrapentafluorophenylaluminum, N,N-diethylaniliniumtetraphenylaluminum, N,N-diethylaniliniumtetrapentafluorophenylaluminum, di Ethylammonium tetrapentatetraphenylaluminum, triphenylphosphoniumtetraphenylaluminum, trimethylphosphoniumtetraphenylaluminum, tripropylammonium tetra(p-tolyl)boron, triethylammoniumtetra(o,p-dimethylphenyl)boron , tributylammonium tetra(p-trifluoromethylphenyl)boron, triphenylcarboniumtetra(p-trifluoromethylphenyl)boron, and triphenylcarboniumtetrapentafluorophenylboron.

When the catalyst composition includes both a carrier and a co-catalyst, it may be prepared by a manufacturing method comprising the steps of supporting the co-catalyst compound on a carrier, and supporting the compound represented by Formula 1 on the carrier, , In this case, the supporting order of the cocatalyst and the compound of Formula 1 may be changed as needed.

In the preparation of the catalyst composition, a hydrocarbon solvent such as pentane, hexane, heptane, or the like, or an aromatic solvent such as benzene or toluene may be used as the reaction solvent.

The polypropylene for filaments may be prepared through a polymerization process in which a catalyst composition including the compound represented by Formula 1 and propylene are brought into contact with each other under hydrogen gas.

At this time, the hydrogen gas may be added so as to be 100 ppm to 500 ppm, or 200 ppm to 400 ppm, or 250 ppm to 350 ppm, in the range of the hydrogen molar content relative to the monomer, based on the total weight of propylene. By controlling the amount of hydrogen gas used, the molecular weight distribution and fluidity of the polypropylene resin composition for filaments produced while exhibiting sufficient catalytic activity can be adjusted within a desired range, and accordingly, a propylene polymer for filaments having appropriate physical properties according to the use can be manufactured.

Specifically, the hydrogen gas activates the inactive sites of the transition metal catalyst and causes a chain transfer reaction to control the molecular weight. Since the compound represented by Formula 1 in the present invention has excellent hydrogen reactivity, it is possible to effectively prepare a polypropylene resin having a desired level of molecular weight and melt index by controlling the amount of hydrogen gas used during the polymerization process.

The polypropylene resin for the filament may be prepared by a continuous polymerization process, for example, a continuous solution polymerization process, a bulk polymerization process, a suspension polymerization process, a slurry polymerization process, or an emulsion polymerization process. Various polymerizations known as polymerization of olefin monomers. process can be employed.

Specifically, the polymerization reaction may be carried out at a temperature of about 40 °C to 110 °C or about 60 °C to 100 °C and a pressure of about 1 kgf/cm ² to 100 kgf/cm ² .

In addition, in the polymerization reaction, the catalyst may be used in a dissolved or diluted state in a solvent such as pentane, hexane, heptane, nonane, decane, toluene, benzene, dichloromethane, chlorobenzene, and the like. In this case, by treating the solvent with a small amount of alkylaluminum or the like, a small amount of water or air that may adversely affect the catalyst may be removed in advance.

The polypropylene for filaments according to an embodiment of the present invention prepared by the above manufacturing method has a narrow molecular weight distribution with a low residual stress ratio and a melt index, so that it is possible to produce a fiber with a thin and uniform thickness, and It not only provides stable processability during spinning, but also realizes excellent toughness that is not easily torn with high strength.

Accordingly, according to another embodiment of the present invention, there is provided a filament including the polypropylene for the filament. In general, the filament comprises at least 95% by weight of the metallocene polypropylene according to the present invention, preferably the filament consists of the metallocene polypropylene according to the present invention. Further, the filaments are mono-filaments or multi-filaments, preferably multi-filaments.

In addition, the filament may have a tenacity of 7.5 gf/denier or more, or 7.5 gf/denier to 10 gf/denier, or 7.7 gf/denier to 8.5 gf/denier, as measured according to ASTM D 638.

In addition, the filament has a draw ratio of 4.5 times or more. The stretching ratio is excellent as the value is higher, and there is practically no limitation on the upper limit, but may be 10 times or less, 9 times or less, or 8 times or less, for example.

The manufacturing method of the filament, except that the polypropylene for the filament according to the present invention is used, a conventional method in the art to which the present invention pertains may be used. For example, the filament according to the present invention may be prepared by melting and spinning the polypropylene for filament according to the present invention at an appropriate temperature in an extruder to prepare a filament, stretching it, and then cooling.

According to the present invention, there can be provided a polypropylene that can be used for manufacturing a filament having excellent spinning processability with high strength.

Hereinafter, preferred embodiments are presented to help the 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 and Comparative Preparation Example: Preparation of Catalyst>

Preparation Example 1

Step 1): Preparation of (n-propylmethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)silane

2-Methyl-4-tert-butyl-phenylindene (10.0 g, Compound 1) was dissolved in 76.2 mL of diethyl ether (Et ₂ O) and cooled to -25 °C. Then, 16.0 mL of n-butyllithium solution (2.5 M, hexane solvent) was slowly added dropwise, followed by stirring at room temperature for 4 hours. Then, it was cooled to -25 °C, 1 mol% of copper cyanide (CuCN) was added, and then 2.92 mL of n-propylmethyldichlorosilane was dissolved in 38 mL of diethyl ether and slowly added dropwise, followed by stirring at room temperature for 16 hours. . Then, dichloromethane (DCM) and water were added to separate the organic layer, and the organic layer was dried with magnesium sulfate (MgSO ₄ ) and filtered, and the solvent was distilled under reduced pressure (n-propylmethylsilane-diyl). -Bis((2-methyl-4-tert-butyl-phenylindenyl)silane (Compound 2) was obtained.

Step 2) Preparation of [(n-propylmethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)]zirconium dichloride

(n-propylmethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)silane (Compound 2) prepared in step 1 was dissolved in 95.3 mL of diethyl ether (Et ₂ O) After dissolution, it was cooled to -25 ° C. 8 mL of n-butyllithium solution (2.5 M) was slowly added dropwise, followed by stirring at room temperature for 4 hours, then cooled to -25 ° C, zirconium tetrachloride tetrahydro 3.59 g of furan complex [ZrCl _4· 2THF] was added dropwise and stirred at room temperature for 16 hours.The solvent of the reaction solution was removed under reduced pressure, then dichloromethane was added and filtered, and the filtrate was distilled off under reduced pressure.Use dichloromethane and recrystallized to obtain [(n-propylmethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)]zirconium dichloride (Compound 3, 1.0 g, yield 14%).

Step 3) Preparation of Supported Catalyst

In a 3 L reactor, 100 g of silica and 10 wt% of methylaluminoxane (670 g) were put and reacted at 90° C. for 24 hours. After precipitation, the upper layer was removed and washed twice with toluene. [(n-propylmethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)]zirconium dichloride (Compound 3) prepared in step 2 was diluted in toluene and added to the reactor After completion of the reaction, the reaction was carried out for 5 hours at 70° C. After the reaction was completed, the upper layer solution was removed, the remaining reaction product was washed with toluene, washed again with hexane, and vacuum dried to form silica-supported metallocene in the form of solid particles. 150 g of catalyst were obtained.

Comparative Preparation Example 1

Instead of the transition metal compound prepared in step 2 of Preparation Example 1, it is [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenyl) represented by the following formula A Neil)] A silica-supported metallocene catalyst was prepared in the same manner as in Step 3 of Preparation Example 1, except that zircorium dichloride was used.

[Formula A]

<Examples and Comparative Examples: Preparation of polypropylene and filament>

Example 1 : Preparation of polypropylene

The 2L stainless reactor was vacuum dried at 65 ° C. and then cooled, and 50 ppm of triethylaluminum (TEAL) was added at room temperature, 300 ppm of hydrogen was added, and 18000 kg/h of propylene was sequentially added. After stirring for 10 minutes, the metallocene-supported catalyst prepared in Preparation Example 1 was introduced into the reactor under nitrogen pressure. Thereafter, the temperature of the reactor was raised to 70° C. within 5 minutes, and then polymerization was performed at a pressure of 39 kg/cm ² for 1 hour. After completion of the reaction, unreacted propylene was vented.

In order to minimize the deformation and damage of the resin at high temperature, based on the amount of the polypropylene polymer powder prepared above, 100-1000 ppm of calcium stearide (neutralizing agent), 100-1000 ppm of Irganox 3114 (first antioxidant), 100-1000 ppm of Irganox 168 (Second antioxidant) 500-1500 ppm of additive was added, strands were pulled out at 180-220 °C at 5-25 kg/h, and the prepared strands were pelleted with a pelletizer of 500-900 rpm. .

Comparative Example 1: Preparation of polypropylene

Commercially available H7411 ^® (manufactured by LG Chem) was used as Z/N homo polypropylene.

Comparative Example 2: Preparation of polypropylene

Polypropylene was prepared in the same manner as in Example 1, except that the metallocene supported catalyst prepared in Comparative Preparation Example 1 was used instead of the metallocene supported catalyst prepared in Preparation Example 1.

Example 2 : Filament Preparation

The polypropylene pellets obtained in Example 1 were fed to an extruder and melted. The molten resin was sent to a spinning unit (screen pack, distributor, die) through a spinning pump, and filaments were manufactured through a die. Specific processing conditions were a spinning temperature of 245 °C, a nozzle diameter of 0.9 mm, the number of nozzles 70, a cooling temperature of 14 °C, a stretching roll temperature of 100-200 °C, and a draw ratio of 7.3. The draw ratio was measured by the take-up roll rotation speed (RPM2) and the take-up roll rotation speed (PRM1) ratio (RPM2/RPM1).

Example 3 : Filament Preparation

A filament was prepared in the same manner as in Example 2, except that the draw ratio was changed to 8.3.

Comparative Example 3 : Preparation of Filament

A filament was prepared in the same manner as in Example 2, except that the polypropylene pellets obtained in Comparative Example 1 were used instead of the polypropylene pellets obtained in Example 1.

Comparative Example 4 : Preparation of Filament

A filament was prepared in the same manner as in Example 3, except that the polypropylene pellets obtained in Comparative Example 1 were used instead of the polypropylene pellets obtained in Example 1.

Comparative Example 5 : Preparation of Filament

A filament was prepared in the same manner as in Example 2, except that the polypropylene pellets obtained in Comparative Example 2 were used instead of the polypropylene pellets obtained in Example 1.

Comparative Example 6 : Preparation of Filament

A filament was prepared in the same manner as in Example 3, except that the polypropylene pellets obtained in Comparative Example 2 were used instead of the polypropylene pellets obtained in Example 1.

<Test Example>

Test Example 1: Measurement of physical properties of polypropylene

The homopolymerization process and the polypropylene obtained therefrom according to Example 1 and Comparative Examples 1 and 2 were evaluated for physical properties in the following manner. The results are shown in Table 1 below.

(1) Melt index (MI, 2.16 kg): Measured at 230 ° C. under a load of 2.16 kg according to ASTM D1238, and expressed as the weight (g) of the polymer melted for 10 minutes.

(2) Stereoregularity (Tacticity, mol%): Using ¹³ C-NMR, the peak areas of PPP (mm), PPP (mr) and PPP (rr) were obtained, and the triad tacticity was calculated based on Equation 1 below. calculated. At this time, a 600 MHz Avance Ⅲ HD NMR of Bruker was used as a measuring instrument, and polypropylene was dissolved in 1.1.2.2-tetrachloroethane solvent and analyzed at 120 °C.

[Equation 1]

Triad tacticity(%) = PPP(mm)/{PPP(mm)+PPP(mr)+PPP(rr)}*100

(3) Melting point (Tm)

After increasing the temperature to 200 °C, it was maintained at that temperature for 5 minutes, then lowered to 30 °C, and then the temperature was increased again, so that the top of the DSC (Differential Scanning Calorimeter, TA) curve was used as the melting point. At this time, the rate of temperature increase and decrease was 10 °C/min, and the melting point was measured in the section where the second temperature was increased.

(4) Molecular weight and molecular weight distribution (MWD, polydispersity index): The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer were measured using gel permeation chromatography (GPC: gel permeation chromatography, manufactured by Waters). , the weight average molecular weight was divided by the number average molecular weight to calculate the molecular weight distribution (PDI). At this time, the analysis temperature was 160 ℃, the solvent was trichlorobenzene, and the molecular weight was measured by standardizing with polystyrene.

(5) Measurement of residual stress ratio

For the homo polypropylene according to the Examples and Comparative Examples, 10 g of each sample was taken and 200% strain was applied at 235° C., and then the change in residual stress was measured for 10 minutes.

A Discovery Hybrid Rheometer (DHR) manufactured by TA Instruments was used to measure the residual stress, and the sample was sufficiently loaded between the upper and lower plates with a diameter of 25 mm, melted at 235° C., and then the gap was fixed at 1 mm for measurement.

Based on the measured residual stress data, the ratio of residual stress (RS%) was calculated according to the following formula 1 and shown in Table 1 below:

[Formula 1]

Residual stress ratio (Y) = (RS ₁ /RS ₀ )*100

In Equation 1, RS ₀ is the residual stress at 0.02 seconds (t ₀ ) after applying 200% strain to the homo polypropylene under 235 ° C., and RS ₁ is the 200% strain applied to the homo polypropylene under 235 ° C. Residual stress at 1.00 sec (t ₁ ) after.

division Example 1 Comparative Example 1 Comparative Example 2 catalyst Metallocene (Preparation Example 1) Ziegler-Natta Metallocene (Comparative Preparation Example 1) MI (g/10min) 6 10 13 Stereoregularity (mol%) 99.5 99.5 Weight average molecular weight (g/mol) 164,000 146,000 130,000 Tm (℃) 151 160 MWD 2.4 3.1 3.0 Residual stress ratio (%) 0.109 0.256 0.224

As a result of the experiment, the homopolypropylene of Examples prepared by the manufacturing method according to the present invention had a low melt index of 6 g/10 min, a high weight average molecular weight of 164,000 g/mol, a narrow molecular weight distribution (MWD) of 2.4, and 0.109 %, indicating a low residual stress ratio.

On the other hand, in the case of the homo polypropylene of Comparative Example 1 prepared using the Ziegler-Natta catalyst, a melt index of 10 g/10 min higher than in Examples, a weight average molecular weight of 146,000 g/mol lower than in Examples, Examples It exhibited a molecular weight distribution (MWD) of 3.1, which was wider than that of , and a residual stress ratio of 0.256%, which was higher than that of Example.

In addition, in the case of the homo polypropylene of Comparative Example 2 using a compound having a different structure as a catalytically active material, a melt index of 13 g/10 min higher than in Examples, a weight average molecular weight of 130,000 g/mol lower than in Examples, It exhibited a molecular weight distribution (MWD) of 3.0 wider than that of Example, and a residual stress ratio of 0.224% higher than that of Example.

Accordingly, the Example can be differentiated from the Comparative Example in that it is possible to prepare a characteristic homopolypropylene that simultaneously satisfies a relatively low melt index, a high weight average molecular weight, a narrow molecular weight distribution, and a low residual stress ratio.

Test Example 2: Measurement of Filament Properties

For the filaments obtained in Examples 2 to 3 and Comparative Examples 3 to 6, physical properties were evaluated in the following manner, and the results are shown in Table 2 below.

(1) Filament strength (tenacity, unit: gf/denier)

The strength means the breaking point strength of the yarn, and was measured according to ASTM D 638. At this time, the test speed was set to 200 mm/min, and 6 measurements were taken per specimen, and the average value was taken. For reference, denier is an international unit used to indicate the thickness of a thread, and a standard length of 9,000m and a unit weight of 1g is 1 denier.

(2) Elongation of filament (%)

It was measured according to ASTM D 638.

(3) Filament workability

The processability of the filaments was evaluated according to the following criteria according to whether or not single yarns occurred in the filaments during manufacturing.

<Evaluation criteria>

Good: When the occurrence of single yarns of fibers is 10% or less

Poor: When the occurrence of single yarns of fibers exceeds 10%

division Example 2 Example 3 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 catalyst Metallocene (Preparation Example 1) Metallocene (Preparation Example 1) Ziegler-Natta Ziegler-Natta Metallocene (Comparative Preparation Example 1) Metallocene (Comparative Preparation Example 1) draw ratio 7.3 8.3 7.3 8.3 7.3 8.3 Strength (g/d) 6.3 7.3 6.0 6.9 5.8 6.2 Elongation (%) 63 56 59 52 53 machinability Good Good Good error Good error

According to an embodiment of the present invention, the filament prepared using the homo polypropylene of Example 1, in which all of MI, MWD, stereoregularity, and residual stress ratio are optimized, has good processability and high strength and high elongation properties under the same draw ratio condition. was shown.

In particular, when comparing the filament of Example 2 and the filament of Example 3, excellent workability is maintained even with an increase in the draw ratio, whereas when the filament of Comparative Example 3 and the filament of Comparative Example 4 are compared, the workability is poor due to the increase in the draw ratio. could check

Claims (12)

Polypropylene for filaments satisfying the following conditions i) to iii) and having a stereoregularity of 99 mol% to 100 mol%:
i) melt index (measured with 2.16 kg load at 230°C according to ASTM D1238) from 1.6 g/10 min to 9 g/10 min,
ii) molecular weight distribution 2.3 to 2.5,
iii) the residual stress ratio according to the following formula 1 is 0.005% to 0.2%,
[Formula 1]
Residual stress ratio = (RS ₁ /RS ₀ )*100
In Equation 1, RS ₀ is the residual stress at any one time point (t ₀ ) less than 0.05 seconds after applying a strain of 200% to the polypropylene for the filament under 235 ° C., RS ₁ is the polypropylene for the filament under 235 ° C. Residual stress at any one time point (t ₁ ) between 0.05 sec and 1.50 sec after applying a strain of 200% to propylene.
According to claim 1,
The polypropylene for filament has a weight average molecular weight (measured by GPC) of 150,000 g/mol to 300,000 g/mol, polypropylene for filament.
delete According to claim 1,
The polypropylene for the filament has a melting point of 140 ℃ to 155 ℃, the polypropylene for the filament.
In the presence of a catalyst composition comprising a compound of Formula 1, adding hydrogen to polymerize a propylene monomer, wherein the hydrogen is added in an amount of 100 ppm to 500 ppm, the polypropylene resin for the filament of claim 1 Way:
[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 silylether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl;
A is carbon, silicon or germanium,
R ₉ is a C _3-10 linear alkyl group, and R ₁₀ is a C _1-2 linear alkyl group.
6. The method of claim 5,
Wherein R ₁ and R ₅ are each independently a phenyl group substituted with a C _3-6 branched chain alkyl group, a method for producing a polypropylene resin for filaments
6. The method of claim 5,
Wherein R ₁ and R ₅ are each tert-butyl phenyl, a method for producing a polypropylene resin for filaments.
6. The method of claim 5,
R ₉ is a normal-propyl group, R ₁₀ is a methyl group, a method for producing a polypropylene resin for filaments.
6. The method of claim 5,
The compound of Formula 1 is a compound represented by the following Formula 1-1, a method for producing a polypropylene resin for filaments:
[Formula 1-1]

delete 6. The method of claim 5,
The catalyst composition is a method for producing a polypropylene resin for filaments, further comprising at least one of a compound represented by the following formula (2), a compound represented by formula (3), and a compound represented by formula (4):
[Formula 2]
-[Al(R ₁₁ )-O] _m -
In Formula 2,
R ₁₁ may be the same as or different from each other, and each independently halogen; C _1-20 hydrocarbons; or a C _1-20 hydrocarbon substituted with halogen;
m is an integer greater than or equal to 2;
[Formula 3]
J(R ₁₂ ) ₃
In Formula 3,
R ₁₂ is as defined in Formula 2 above;
J is aluminum or boron;
[Formula 4]
[EH] ⁺ [ZA ₄ ] ^- or [E]+[ZA ₄ ] ^-
In Formula 4,
E is a neutral or cationic Lewis base;
H is a hydrogen atom;
Z is a group 13 element;
A may be the same or different from each other, and each independently represents a C _6-20 aryl group or 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. .
A filament comprising the polypropylene for the filament of claim 1.