KR102584265B1 - Polypropylene-based nonwoven fabric and method for preparing the same - Google Patents

Abstract

The present invention provides a polypropylene-based nonwoven fabric with increased bulkiness and improved differential pressure, and a method for manufacturing the same.

Description

Polypropylene-based nonwoven fabric and method for manufacturing the same {POLYPROPYLENE-BASED NONWOVEN FABRIC AND METHOD FOR PREPARING THE SAME}

The present invention relates to a polypropylene-based nonwoven fabric with increased bulkiness and improved differential pressure and a method for manufacturing the same.

In general, non-woven fabric refers to a sheet or web structure manufactured by adhering or bonding fibers, threads, or filaments to each other by mechanical, thermal, or chemical adhesion without going through a weaving, weaving, or knitting process. It is also called adhesive fabric and bonded fabric. These nonwoven fabrics can be manufactured by various methods, including needle punching method, chemical bonding method, thermal bonding method, melt blown method, spunlace method, stitch bond method, and spunbond method.

Among these, the melt blown method is a method in which high-temperature and high-pressure air flows into the exit of the spinning nozzle to stretch and open fibers and then accumulate them on a collection conveyor. The single fiber diameter is about 1 to 10 microns (general fibers are 10 microns). Because it can produce ultrafine fiber sheets (~30 micron), it is mainly used in the production of nonwoven fabrics for filters.

In the case of melt-blown nonwoven fabrics made from polypropylene resins, high-flow polypropylene was previously obtained by applying a Ziegler-Natta catalyst, and then melt-spun to produce polypropylene fibers and non-woven fabrics containing the same. However, since the Ziegler-Natta catalyst has low hydrogen reactivity, in order to produce high-flow polypropylene by applying it, vis-breaking or controlled rheology is required using a peroxide-based decomposition accelerator. Rheology (CR) process had to be performed.

In this case, due to the action of the peroxide-based decomposition accelerator, the heat resistance and weather resistance of the final manufactured fiber and nonwoven fabric became poor, resulting in discoloration and shrinkage. In addition, there was a disadvantage in that the mechanical properties and other physical properties of the nonwoven fabric deteriorated during secondary processing and storage to apply the nonwoven fabric to various uses such as filters, masks, or sound absorbers. Moreover, in the case of polypropylene resin manufactured using a Ziegler-Natta catalyst, the molecular weight distribution is wide, so there is a limit to fine fiberization, and the fiber thickness deviation is large, resulting in self-bonding. As a result, the bulkiness decreases and the differential pressure increases, which limits its application to filters, masks, etc.

Meanwhile, polypropylene resin produced with a metallocene catalyst has a narrow molecular weight distribution, so it is possible to produce thin and uniform fibers, and thus has the advantage of producing a low basis weight nonwoven fabric with excellent strength. However, metallocene homopolypropylene resin has low xylene solubility or low molecular weight content due to narrow molecular weight distribution, so it gives a rough feel to the surface when manufacturing non-woven fabrics, and has insufficient fineness or spinning instability. As a result, there is a problem that the occurrence of flies increases and the differential pressure increases as a result.

Recently, as the demand for nonwoven fabrics for filters has increased due to environmental problems such as fine dust and yellow dust, high collection efficiency and low differential pressure characteristics are required for filters used in masks, air purifiers, etc. Currently used filters such as KF94/99 and HEPA can achieve high collection efficiency through electrostatic treatment, but in the case of low differential pressure, they must form a uniform web of non-woven fabric and have high bulkiness. The bulkiness is controlled by fine tuning the distance between die and collector (DCD) during the melt blowing process.

However, the fiber diameter deviation due to the high residual heat and wide molecular weight distribution of the resin increases self-bonding between fibers, so there is a limit to improving bulkiness.

Accordingly, the present invention provides a polypropylene-based nonwoven fabric with excellent fineness, increased bulkiness, and improved differential pressure, and a method for manufacturing the same.

The present invention includes a fiber containing a polypropylene-based resin,

The polypropylene-based resin includes homopolypropylene that satisfies the conditions a1) to a3) below,

Provided is a polypropylene-based nonwoven fabric having a bulkiness of 0.1 mm or more and a differential pressure of 0.05 KPa or less under the condition of a non-woven basis weight of 20 gsm:

a1) Recrystallization temperature (Trc) 120℃ or higher

a2) Molecular weight distribution: 2.4 or less

a3) Melting point (Tm) 150 to 160°C

Additionally, according to another embodiment of the present invention,

Polymerizing a propylene monomer while introducing hydrogen gas in the presence of a catalyst composition containing a transition metal compound represented by the following formula (1) to produce homopolypropylene that satisfies the conditions of a1) to a3) above;

Extruding and pelletizing the composition containing the homo-polypropylene at a temperature of 200 to 250° C. to produce a pellet-shaped polypropylene resin; and

For the polypropylene resin, performing a melt blowing process of injecting air at a temperature of 285 to 315 ° C. at a pressure of 2.5 to 4.5 psi and melt spinning at a melt temperature of 235 to 255 ° C. The polypropylene-based nonwoven fabric described above, including Provides a manufacturing method of:

[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-based nonwoven fabric manufactured according to the present invention exhibits excellent fineness while exhibiting increased bulkiness and improved differential pressure characteristics. Accordingly, it can be very preferably applied to filters and masks in various fields that require high collection efficiency and low differential pressure characteristics.

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.

The present inventors have prepared homopolypropylene with a narrow molecular weight distribution and high recrystallization temperature by polymerizing propylene monomer in the presence of a catalyst composition containing a transition metal compound of a specific structure and the addition of hydrogen gas, under controlled conditions. By extruding and pelletizing, a pellet-shaped polypropylene resin with physical properties equivalent to that of the homo polypropylene is manufactured, and then a melt blowing process is performed on the produced polypropylene-based resin under controlled conditions to maintain excellent fineness. The invention was completed after confirming that it was possible to manufacture a nonwoven fabric with increased bulkiness and low differential pressure.

Specifically, the polypropylene-based nonwoven fabric according to one embodiment of the invention,

Contains fiber containing polypropylene-based resin,

The polypropylene-based resin includes homopolypropylene that satisfies the conditions a1) to a3) below,

Under the condition of a nonwoven basis weight of 20 gsm, the bulkiness is 0.1 mm or more and the differential pressure is 0.05 KPa or less:

a1) Recrystallization temperature (Trc) 120℃ or higher

a2) Molecular weight distribution: 2.4 or less

a3) Melting point (Tm) 150 to 160°C

The above-mentioned polypropylene-based nonwoven fabric is a homopolymer that satisfies the conditions a1) to a3) by polymerizing propylene monomer while introducing hydrogen gas in the presence of a catalyst composition containing a transition metal compound represented by the following formula (1). Preparing polypropylene (step 1);

Extruding and pelletizing the composition containing the homo-polypropylene at a temperature of 200 to 250° C. to produce a pellet-shaped polypropylene resin (step 2); and

For the polypropylene resin, performing a melt blowing process (step 3) of injecting air at a temperature of 285 to 315°C at a pressure of 2.5 to 4.5 psi and melt spinning at a melt temperature of 235 to 255°C (step 3); Can be manufactured by:

[Formula 1]

In Formula 1,

X ₁ and X ₂ are the same as or different from each other and are each independently halogen,

R ₁ and R ₅ are the same or different from each other, and 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 the same or different from each other, and are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silyl Alkyl, 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 C1-20 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, 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, 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.

Hereinafter, the method for manufacturing the polypropylene-based nonwoven fabric according to one embodiment of the invention will be described in more detail for each step.

(Step 1)

In the method for producing a polypropylene-based nonwoven fabric, step 1 is to polymerize a propylene monomer while introducing hydrogen gas in the presence of a catalyst composition containing a transition metal compound represented by Formula 1, thereby producing homopolypropylene. It's a step.

The transition metal compound represented by Formula 1 is a type of metallocene catalyst and has excellent hydrogen gas reactivity. Therefore, it is possible to form high-flow homo-polypropylene by controlling the molecular weight of homo-polypropylene without using a separate peroxide-based decomposition accelerator. Accordingly, it is possible to suppress the decrease in heat resistance or weather resistance of fibers and/or nonwoven fabrics caused by the peroxide-based decomposition accelerator.

Furthermore, due to the use of the transition metal compound, homo polypropylene with a narrow molecular weight distribution and a high recrystallization temperature is formed, so that polypropylene-based fibers with fine fineness and non-woven fabrics containing the same can be effectively formed. .

In addition, as confirmed in the examples described later, the polypropylene-based nonwoven fabric manufactured using the transition metal compound of Formula 1 was confirmed to have high bulkiness and low differential pressure compared to the case where a catalyst of similar structure was used.

Therefore, according to one embodiment of the invention, a polypropylene-based nonwoven fabric having fine fineness, high bulkiness, and low differential pressure characteristics can be manufactured, and such nonwoven fabric is very useful for use as filters, masks, or sound absorbing materials in various fields. It can be preferably applied.

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

Moreover, the transition metal compound is a bridge group that connects two ligands containing an indenyl group, and contains a divalent functional group A 2 substituted with an ethyl group, thereby increasing the available angle by increasing the atomic size compared to the existing carbon bridge, thereby increasing the monomer's strength. It is easily accessible and can exhibit superior 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 transition metal compound contains zirconium (Zr) as a central metal, so it has more orbitals that can accept electrons compared to other group 14 elements such as Hf, and thus has a higher affinity with monomers. It can be easily combined, and as a result, it can exhibit a superior catalytic activity improvement effect.

More specifically, in the transition metal compound, in Formula 1, R ₁ and R ₅ are each independently a C _6-12 aryl group substituted with C _1-10 alkyl, or more specifically, C _3- such as tert-butyl phenyl. ₆ It may be a compound that is a phenyl group substituted with a branched 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.

In addition, the transition metal compound may be a compound in Formula 1 where R ₂ to R ₄ and R ₆ to R ₈ are each independently hydrogen, X ₁ and X ₂ are each independently chloro, and A is silicon.

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

(1a)

The transition metal compound can be synthesized by applying known reactions, and more detailed synthesis methods can be referred to the production examples described below.

Meanwhile, the transition metal compound may be used as a single component or may be used as a supported catalyst supported on a 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.

Specific examples of the carrier include silica, alumina, magnesia, silica-alumina, silica-magnesia, etc., and these are usually oxides such as Na ₂ O, K ₂ CO ₃ , BaSO ₄ , and Mg(NO ₃ ) ₂ , may further include carbonate, sulfate, and nitrate components. Among these, when using a silica carrier, the transition metal compound is supported by chemically bonding with reactive functional groups such as siloxane groups present on the surface of the silica carrier, so there is almost no catalyst released from the surface of the carrier during the propylene polymerization process. As a result, when producing polypropylene through slurry or vapor phase polymerization, fouling that occurs on the reactor wall or between polymer particles can be minimized.

When the transition metal compound is supported on a carrier, for example, when the carrier is silica, the content of the transition metal compound is 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. It can be supported as . 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.

Specifically, the cocatalyst may include a compound represented by the following formula (2):

[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.

Specific examples of the compound represented by Formula 2 include C _1-20 alkyl aluminoxane compounds such as methylaluminoxane, ethyl aluminoxane, isobutyl aluminoxane, or butyl aluminoxane, any one or two or more of these. Mixtures may be used.

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

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.

The catalyst composition having the above structure can be prepared by a manufacturing 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.

Next, a process for producing homopolypropylene is performed through a polymerization process in which a catalyst composition containing the transition metal compound of Formula 1 and a 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 controlling the amount of hydrogen gas used during the polymerization process, polypropylene having a desired level of molecular weight and melt index can be effectively obtained.

The hydrogen gas may be added in an amount of 700 ppmw or more, or 900 ppmw, or 1500 ppmw or less, or 1200 ppmw or less, based on the total weight of propylene monomer. As polymerization proceeds while supplying hydrogen gas at this amount, homo polypropylene with a narrow molecular weight distribution and high fluidity can be produced.

In addition, the polymerization reaction of the homo polypropylene 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 hired. In particular, in order to realize narrow molecular weight distribution and high fluidity in the produced homo polypropylene, 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.

In addition, the polymerization reaction is performed at a temperature of 40°C or higher, or 60°C or higher, or 70°C or higher, a temperature of 110°C or lower or 100°C or lower, and a temperature of 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.

In addition, during the polymerization reaction, trialkylaluminum such as triethylaluminum may be selectively added in an amount of 40 to 200ppmw based on the total weight of the propylene monomer. If moisture or impurities exist in the polymerization reactor, part of the catalyst is decomposed. Since the trialkylaluminum serves as a scavenger to capture moisture or impurities present in the reactor in advance, it is used in the production of the catalyst. Activity can be maximized, and as a result, homo polypropylene that meets the above-mentioned physical property requirements can be manufactured more efficiently.

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.

Homo polypropylene manufactured through the polymerization process described above exhibits a high recrystallization temperature, melting point, and narrow molecular weight distribution due to the use of a metallocene-based compound with excellent hydrogen reactivity. Accordingly, when manufacturing a pellet-type polypropylene resin composition, excellent fiber processability can be exhibited without the need for a visbreaking process using a decomposition accelerator, and since the decomposition accelerator used in the visbreaking process is not used, the produced resin composition Deterioration of heat resistance and oxidation stability can be prevented.

Specifically, homo polypropylene prepared according to Step 1 above exhibits a high recrystallization temperature (Trc) of 120°C or higher. If the recrystallization temperature is less than 120°C, heat resistance decreases, and there is a risk of decomposition due to heat when processing the fiber at high temperatures. However, homopolypropylene produced according to step 1 can exhibit high stereoregularity and excellent heat resistance by having a high recrystallization temperature as described above, and is rapidly crystallized during the subsequent extrusion process, making it possible to manufacture pellet-type resin. It is easy, and self-binding can be suppressed during fiber production. More specifically, the homo polypropylene may be 120.5°C or higher, or 121°C or higher, and 140°C or lower, or 130°C or lower. In the present invention, the recrystallization temperature (Trc) of the homo polypropylene can be measured using a Differential Scanning Calorimeter (manufactured by TA). Specifically, the temperature of the resin is increased to 200°C and then measured for 5 minutes. The temperature is maintained at that temperature, then lowered to 30°C, again increased at 10°C/min to 200°C, and then lowered again to 10°C/min. The top of the DSC curve is taken as the recrystallization temperature.

In addition, the homo polypropylene may exhibit a narrow molecular weight distribution (MWD) of 2.4 or less. As a result, radiation stability is good and no flies occur. Additionally, by reducing the variation in fiber thickness, self-binding is reduced due to a decrease in fibers on the thicker side. If the molecular weight distribution exceeds 2.4, spinning stability decreases, fiber thickness deviation increases, and self-binding may occur. More specifically, the MWD of the homo polypropylene is 2.3 or less, or 2.25 or less, and 2.0 or more, or 2.1 or more. In the present invention, the molecular weight distribution (MWD) of the homo polypropylene is obtained by measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polypropylene resin composition using gel permeation chromatography (GPC), respectively. Molecular weight distribution can be determined by calculating the ratio of weight average molecular weight to average molecular weight (Mw/Mn). The specific measurement method is explained in more detail in the test examples below.

Additionally, the homopolypropylene has a high melting point (Tm) of 150 to 160°C. By having such a high melting point, the recrystallization temperature increases, high stereoregularity can be achieved, and as a result, excellent heat resistance can be exhibited. If the melting point is less than 150°C, heat resistance decreases, and there is a risk of decomposition due to heat when processing the fiber at high temperatures. More specifically, the melting point of the homo polypropylene is 155°C or higher, or 156°C or higher, and 160°C or lower.

Meanwhile, in the present invention, the melting point of the homo polypropylene is determined by increasing the temperature of the resin composition to 200°C, maintaining it at that temperature for 5 minutes, then lowering it to 30°C, and then increasing the temperature again to determine DSC ( (Differential Scanning Calorimeter, manufactured by TA) The temperature corresponding to the top of the curve is taken as the melting point. At this time, the speed of temperature rise and fall is 10°C/min, respectively, and the melting point is the result of measurement in the second temperature rise section.

(Step 2)

Next, step 2 is a step of preparing a composition containing the homo polypropylene prepared in step 1 and extruding and pelletizing it at a temperature of 200 to 250 ° C to produce a pellet-shaped polypropylene resin.

In the present invention, pellets or pellet-type are small particles or pieces formed by extrusion of raw materials, and all shapes classified as pellets in the art, such as circular, polygonal, and rod shapes, are used in the present invention. Includes.

Polypropylene resin for manufacturing non-woven fabrics is usually in powder form. However, in this case, fiber processability is poor due to MI deviation and additive distribution unevenness, fineness is not easy, and spinning stability is not good when manufacturing non-woven fabric. There is also a problem with a lot of fine dust being generated during the manufacturing process.

In contrast, in the present invention, by manufacturing in a pellet form, the occurrence of flies can be suppressed, spinning stability can be improved, and fineness uniformity and fineness can be achieved. Moreover, as described above, the homo polypropylene prepared in step 1 has a high recrystallization temperature, so the crystallization rate is fast during melt extrusion, and as a result, it is easy to pelletize.

The composition containing the homo polypropylene may optionally further include an antioxidant and a lubricant along with the homo polypropylene prepared in step 1.

In conventional resin compositions in the form of powder rather than pellets, antioxidants are added to polypropylene in the powder form, so not only does the distribution uniformity of the antioxidants deteriorate, but it is also difficult to distribute them inside the powder, so the effect of adding antioxidants is not sufficient. In contrast, in the present invention, the antioxidant is mixed with homopolypropylene having the above-mentioned high recrystallization temperature and narrow molecular weight distribution and then pelletized, so that the antioxidant is uniformly dispersed, resulting in a better thermal decomposition prevention effect and improved fiber processability. can represent.

As the antioxidant, a phenol-based antioxidant may be used, which has excellent properties in preventing decomposition by heat compared to common antioxidants such as phosphorus-based antioxidants. Specific examples of the phenolic antioxidant include tetrakis(methylene(3,5-di-t-butyl-4-hydroxy)hydrosilylate), 1,3,5-trimethyl-tris(3,5-di- t-butyl-4-hydroxybenzene), or pentaerythritol tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate) (Irganox 1010™, manufactured by BASF) and the like, and any one or a mixture of two or more of these may be used.

Additionally, the antioxidant may be included in an amount of 0.01 to 1 part by weight based on 100 parts by weight of homopolypropylene. If the antioxidant content is less than 0.1 part by weight, the improvement effect due to the use of the antioxidant is minimal, and if it exceeds 1 part by weight, there is a risk of viscosity decrease and discoloration due to excessive antioxidant. More specifically, the antioxidant may be included in an amount of 0.05 parts by weight or more, or 0.1 parts by weight or more, and 0.5 parts by weight or less, or 0.3 parts by weight or less.

In addition, the lubricant has excellent anti-oxidation properties, and when used in combination with the high fluidity homo polypropylene, it can effectively prevent decomposition by oxygen or heat in the air, thereby further improving fiber processability. The lubricant may include organometallic compounds such as calcium stearate, aluminum para-tertiary butyl benzoic acid, sodium benzoic acid, or calcium benzoic acid, and any one or a mixture of two or more of these may be used.

The lubricant may be included in an amount of 0.01 parts by weight or more and 0.05 parts by weight or less based on 100 parts by weight of homopolypropylene. If the amount of lubricant added is less than 0.01 parts by weight, the effect of preventing oxidation and improving fiber processability due to the addition of lubricant is minimal, and if it exceeds 0.05 parts by weight, there is a risk of discoloration due to excessive lubricant.

In addition, the composition may further include one or more additives such as a neutralizer, slip agent, anti-blocking agent, UV stabilizer, and antistatic agent. The content of these additives is not particularly limited, and for example, they 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, respectively, based on the total weight of homo polypropylene.

The extrusion and pelletizing process for the composition described above can be performed according to a conventional extrusion method, such as using a twin-screw extruder, except that the die temperature for melting the composition is controlled to a temperature range of 200 to 250 ° C. there is.

During extrusion, the die temperature lowers the temperature of the molten resin, thereby increasing the viscosity and making pelletization possible. The die temperature may be determined depending on the composition of the composition and the physical properties of the pellet-type polypropylene resin to be manufactured, and in the present invention, the die temperature may be 200 to 250°C. If the die temperature is less than 200°C, there is a risk that the homopolypropylene in the composition may not sufficiently melt and be sufficiently pelletized, or may solidify and block the inside of the die, thereby reducing productivity. Additionally, if the die temperature exceeds 250°C, the viscosity becomes too low and the material flows like a fluid, making pellet production difficult, such as cutting into pellet form. More specifically, the die temperature may be 200°C or higher, or 220°C or higher, and may be performed at a temperature of 240°C or lower or 230°C or lower.

In addition, when the pressure is further controlled along with the die temperature, the die pressure may be 20 bar or more, or 30 bar or more, and 50 bar or less, or 35 bar or less. When controlling the pressure within this range, the shape and physical properties of the pellet-type polypropylene resin can be more easily implemented.

The polypropylene resin prepared by the above method has a pellet form, contains homopolypropylene and optionally an antioxidant and a lubricant, and exhibits physical properties similar to homopolypropylene, such as a high recrystallization temperature and narrow molecular weight distribution.

Specifically, the pellet-type polypropylene resin has a high recrystallization temperature (Trc) of 120°C or higher. Accordingly, it has high stereoregularity and can exhibit excellent heat resistance. On the other hand, if the recrystallization temperature is less than 120°C, heat resistance is reduced and there is a risk of decomposition due to heat during fiber processing at high temperatures. More specifically, the recrystallization temperature of the pellet-type polypropylene resin is 120°C or higher, and considering excellent thermal stability along with sufficient processability required for fiber processing, it is 140°C or lower, or 130°C or lower.

The recrystallization temperature (Trc) of the pellet-type polypropylene resin can be measured using a DSC (Differential Scanning Calorimeter, manufactured by TA) as described above, and the specific measurement method will be described in more detail in the test examples below.

Additionally, the pellet-type polypropylene resin exhibits a narrow molecular weight distribution (MWD) of 2.4 or less. As a result, it exhibits excellent fiber processability and fine fiberization is possible. More specifically, MWD may be 2.3 or less, or 2.2 or less, and 2.0 or more, or 2.1 or more.

In addition, the pellet-type polypropylene resin has a number average molecular weight (Mn) of 15,000 to 20,000 g/mol, more specifically, 17,000 to 19,500 g/mol, or 17,500 to 18,000 g/mol, and a weight average molecular weight (Mw) of 30,000. to 50,000 g/mol, more specifically 35,000 to 45,000 g/mol, or 38,000 to 40,000 g/mol. By having such a narrow molecular weight distribution, as well as a weight average molecular weight and a number average molecular weight in the above range, excellent mechanical properties can be exhibited when manufacturing nonwoven fabric.

As described above, the molecular weight distribution, weight average molecular weight, and number average molecular weight of the polypropylene resin were determined by measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polypropylene resin, respectively, using gel permeation chromatography (GPC). After measurement, the molecular weight distribution can be determined by calculating the ratio of the weight average molecular weight to the number average molecular weight (Mw/Mn), and the specific measurement method is described in more detail in the test examples below.

Additionally, the pellet-type polypropylene resin has a high melting point (Tm) of 150 to 160°C. By having such a high melting point, the recrystallization temperature increases, high stereoregularity can be achieved, and as a result, excellent heat resistance can be exhibited. If the melting point is less than 150°C, heat resistance decreases, and there is a risk of decomposition due to heat when processing the fiber at high temperatures. More specifically, the melting point of the pellet-type polypropylene resin is 155°C or higher, or 156°C or higher, and considering excellent thermal stability along with sufficient processability required for fiber processing, the melting point is 160°C or lower, or 158°C. It may be below.

Meanwhile, in the present invention, the melting point of the pellet-type polypropylene resin can be measured using a DSC (Differential Scanning Calorimeter, manufactured by TA), and the specific method is described in detail in the test examples below.

In addition, the pellet-type polypropylene resin exhibits a high melt index (MI) of 500 g/10 min or more, more specifically 500 to 1300 g/10 min, when measured under a load of 2.16 kg at 230°C according to ASTM D 1238. , As a result, excellent fiber processability can be shown. In the present invention, fiber processability means producing finer fibers and higher strength fibers by enabling stretching at a high magnification due to uniform molecular weight distribution when performing a stretching process during processing. If MI is less than 500 g/10min, there is a risk that processing pressure will increase and processability may be reduced, but the pellet-type polypropylene resin according to the present invention has a high melt index of 500 g/10min or more, so it is fine and has high strength. of fiber production is possible. More specifically, it indicates a melt index of 1000 to 1250 g/10 min.

In addition, the pellet-type polypropylene resin has xylene solubles (Xs) of 0.6% by weight or less, showing high tacticity.

In the present invention, the xylene soluble portion is obtained by dissolving a polypropylene resin in xylene, cooling it, crystallizing the insoluble portion from the resulting cooled solution, and measuring the content (% by weight) of the soluble polymer in the determined cooled xylene. In other words, the xylene soluble fraction contains polymer chains of low stereoregularity. Accordingly, it can be seen that the lower the xylene soluble content, the higher the stereoregularity of the polymer. The polypropylene resin according to one embodiment of the present invention has a low xylene soluble content of 0.6% by weight or less, has high stereoregularity, and as a result can exhibit excellent rigidity and flexural modulus. More specifically, the xylene soluble content of the polypropylene resin may be 0.1% by weight or more, or 0.2% by weight or more, and 0.5% by weight or less, or 0.4% by weight or less.

Meanwhile, in the present invention, the xylene soluble part of the pellet-type polypropylene resin is specifically pretreated by adding xylene to a sample of polypropylene resin, heating it at 135 ° C. for 1 hour, and cooling it for 30 minutes, then using OminiSec equipment. (Viscotek FIPA) flows xylene at a flow rate of 1 mL/min for 4 hours to stabilize the base lines of RI, DP, and IP, and then measures them by entering the concentration and injection amount of the pretreated sample. It can be measured by calculating the peak area.

Pellet-type polypropylene, which has the physical properties described above, has excellent fiber processability without the use of peroxide-based decomposition accelerators used in conventional fiber production, enables fine fiber formation, and can exhibit excellent heat resistance and oxidation stability. Accordingly, it is particularly useful in textile manufacturing fields that require excellent filtration efficiency, such as filters and masks.

(Step 3)

Next, step 3 is a step of manufacturing a nonwoven fabric by performing a melt blowing process on the pellet-type polypropylene resin prepared in step 2.

When manufacturing fibers and non-woven fabrics using the melt blowing process, high temperature and high pressure air is injected into the melt-spun polypropylene resin. At this time, the high temperature and high pressure process injected causes stretching and opening of the fibers being spun. , the fineness is made by adjusting the distance between die and collector (DCD).

In the present invention, it is possible to manufacture thin and uniform fibers by controlling the melting point of the polypropylene resin and the temperature and pressure of the incoming air. As a result, a non-woven fabric with high bulkiness and low differential pressure characteristics can be manufactured. . Additionally, it is possible to suppress fly generation during the melt blowing process.

Specifically, the melt blowing process may be performed by injecting air at a temperature of 285 to 315°C at a pressure of 2.5 to 4.5 psi and melt spinning the pellet-type polypropylene resin at a melt temperature of 235 to 255°C.

If the temperature of the injected air is less than 285℃ or the pressure is less than 2.5 psi, the fineness of the manufactured fiber increases and the pore size in the nonwoven fabric increases, which reduces bulkiness and makes it difficult to obtain a sufficient differential pressure improvement effect. , Also, if the air temperature exceeds 315°C or the pressure exceeds 4.5 psi, spinning stability decreases and fly generation increases, making it difficult to obtain sufficient differential pressure improvement effect. More specifically, it may be more desirable for the input air to have a temperature of 290 to 310°C and a pressure of 3 to 4 psi.

In addition, if the melting temperature for the polypropylene resin, that is, the melt die temperature, is less than 235°C, there is a risk that the polypropylene resin is not melted sufficiently, and as a result, the fineness increases or the diameter deviation of the fiber increases, resulting in self-binding. There is a risk that this may occur, and as a result, the effect of improving differential pressure may be reduced. Additionally, if the melting temperature exceeds 255°C, there is a risk of decomposition and oxidation of the polypropylene resin. More specifically, it may be more preferable that the melting temperature for the polypropylene resin is 240 to 250°C.

In addition, in addition to the above-mentioned conditions, the distance (DCD) between the melt die where the polypropylene resin melts and the collector where the melt-spun fibers are collected is controlled to 10 to 30 cm, more specifically 15 to 25 cm, thereby further improving the fineness described above. It can be promoted. If the DCD is shorter than 10cm, the fineness becomes thicker, and if it exceeds 30cm, there is a risk that spinning stability will decrease and the occurrence of flies may increase.

Through the above process, a nonwoven fabric having excellent fineness and high bulkiness and differential pressure characteristics is manufactured.

Specifically, the nonwoven fabric includes fibers of a polypropylene-based resin containing the above-described homopolypropylene, and the fibers have an average diameter of 2 ㎛ or less, more specifically 1 to 2 ㎛, and the standard deviation of the fiber diameter is 0.6 ㎛ or less, more specifically 0.1 to 0.6 ㎛. At this time, the diameter of the fiber may be defined as the longest straight line distance connecting any two points on the cross section of the fiber.

In addition, the nonwoven fabric includes pores formed between fibers, and the average diameter of the pores is 10 ㎛ or more, more specifically 10 to 15 ㎛. By including such large pores, low differential pressure characteristics can be exhibited, and as a result, filter clogging can be prevented when applied as a filter.

By including fine fibers and large pores as described above, the nonwoven fabric can exhibit a high bulkiness of 0.1 mm or more, more specifically 0.1 to 0.15 mm, or 0.105 to 0.14 mm, under the condition of a nonwoven basis weight of 20 gsm, As a result 0.2 g/cm ³ Hereinafter, more specifically, 0.01 to 0.2 g/cm ³ or 0.1 to 0.2 g/cm ³ It can exhibit a low density of 0.05 KPa or less, more specifically, a low differential pressure of 0.01 to 0.05 KPa.

Accordingly, it can be very preferably applied as a filter, mask, or sound-absorbing material for various purposes.

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.

Synthesis 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)

Synthesis Example 2: Preparation of catalyst

A silica-supported metallocene catalyst was prepared in the same manner as Synthesis Example 1, except that a transition metal compound (I) having the structure below was used instead of the transition metal compound of Formula 1a.

(I)

<Manufacture of homopolypropylene>

Manufacturing Example 1

In the presence of the silica-supported metallocene catalyst prepared in Synthesis Example 1, bulk-slurry polymerization of propylene was performed using two consecutive loop reactors.

At this time, triethylaluminum (TEAL) and hydrogen gas were each introduced using a pump in the amounts shown in Table 1 below, and for bulk-slurry polymerization, 16.7 weight of the supported catalyst prepared according to Preparation Example 1 or Comparative Preparation Example 1 was added. It was used in the form of a mud catalyst mixed with oil and grease to achieve a % content. The reactor was operated at a temperature of 70°C and a production volume of approximately 40 kg per hour. The propylene input amount was set to 40 kg/h, and the specific reaction conditions for the remaining polymerization process were as shown in Table 1 below to prepare homopolypropylene.

Comparative Manufacturing Example 1

Homopolypropylene was prepared in the same manner as in Preparation Example 1, except that the silica-supported metallocene catalyst prepared in Synthesis Example 2 was used and performed under the conditions shown in Table 1 below.

Test example 1

The physical properties of the homopolypropylene prepared in Preparation Example 1 and Comparative Preparation Example 1 were evaluated in the following manner. The results are shown in Table 1 below.

(1) Recrystallization temperature (Trc) (°C): Increase the temperature of homopolypropylene to 200°C, maintain it at that temperature for 5 minutes, then lower to 30°C, and then lower the temperature by 10°C to 200°C. The top of the curve (Differential Scanning Calorimeter, manufactured by TA) in the section where the temperature was increased to 10°C/min and then lowered to 10°C/min was taken as the recrystallization temperature.

(2) Molecular weight distribution (MWD): Measure the weight average molecular weight (Mw) and number average molecular weight (Mn) of homo polypropylene using gel permeation chromatography (GPC), and calculate the measured weight average molecular weight. The molecular weight distribution (MDW, i.e. Mw/Mn) was calculated by dividing 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. The samples of homo polypropylene prepared in Preparation Example 1 and Comparative Preparation Example 1 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.

(3) Melting point (Tm) (℃): After increasing the temperature of homopolypropylene to 200 ℃, maintaining it at that temperature for 5 minutes, then lowering it to 30 ℃, increasing the temperature again, and measuring by DSC (Differential Scanning Calorimeter) , manufactured by TA Corporation), the top of the curve was taken as the melting point. At this time, the rate of temperature rise and fall was 10°C/min, and the melting point was measured in the second temperature rise section.

In Table 1 above, the amount of hydrogen input is based on the total weight of propylene monomer.

<Manufacture of polypropylene resin composition>

Example 1-1

Based on 100 parts by weight of homopolypropylene prepared in Preparation Example 1, 0.02 parts by weight of calcium stearate lubricant and 0.10 parts by weight of antioxidant (Irganox™ 1010) were mixed, and granulated at an extrusion temperature of 220°C using a twin-screw extruder. Pellets of polypropylene resin composition were prepared.

Comparative example 1-1

The same method as in Example 1-1 was carried out except that commercially available H7912™ (manufactured by LG Chemical) was used as Z/N homopolypropylene and each component was used in the formulation shown in Table 2 below. A polypropylene resin composition was prepared.

Comparative example 1-2

A polypropylene resin composition was produced in the same manner as in Example 1-1, except that the homo polypropylene prepared in Comparative Preparation Example 1 was used and each component was used in the formulation shown in Table 2 below. Manufactured.

Test example 2

For the polypropylene resin compositions prepared in the above examples and comparative examples, the physical properties were measured and evaluated in the following manner. The results are shown in Table 2.

(1) Melt Index (MI, 2.16 kg) (g/10min): For polypropylene resin compositions, measured with a load of 2.16 kg at 230°C according to ASTM D1238, the weight (g) of polymer melted for 10 minutes It is expressed as

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

(3) Recrystallization temperature (Trc) (°C): The temperature of the polypropylene resin composition is increased to 200°C, maintained at that temperature for 5 minutes, then lowered to 30°C, and then lowered to 200°C for 10 minutes. The top of the curve (Differential Scanning Calorimeter, manufactured by TA) in the section where the temperature was increased to ℃/min and then lowered to 10℃/min was taken as the recrystallization temperature.

(4) Xylene Soluble (% by weight): Xylene was added to each sample of polypropylene resin composition, heated at 135°C for 1 hour, and cooled for 30 minutes for pretreatment. When the base lines of RI, DP, and IP are stabilized by flowing xylene for 4 hours at a flow rate of 1 mL/min in the OminiSec (FIPA, Viscotek) equipment, enter the concentration and injection amount of the pretreated sample and measure the peak area. was calculated.

(5) Color (Yellow index)

It was measured at a temperature of 25°C according to the standard method of ASTM D1925 (measuring device: X-rite CE7000A).

(6) Number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (MWD): Using gel permeation chromatography (GPC), the weight average molecular weight (Mw) and number average molecular weight of the polymer ( 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.

Example Comparative example 1-1 1-1 1-2 Homo polypropylene types Manufacturing Example 1 H7912™
(LG Chemical Company) Comparative Manufacturing Example 1 Calcium stearate (parts by weight) 0.02 - 0.02 Antioxidants (parts by weight) 0.10 - 0.10 Decomposition accelerator*
(part by weight) - 0.05 - MI (g/10min) 1210 1220 1270 Tm 156 161 154 Trc 121 118 110 Xylene soluble content (% by weight) 0.6 1.8 0.6 Color (Yellow Index) -1.2 -1.2 -1.2 Mn (g/mol) 17900 13600 17500 Mw (g/mol) 38600 53700 37500 MWD 2.22 3.71 2.19

*Decomposition accelerator: PEROXIDE-based decomposition accelerator (Lupersol™ 101, manufactured by Arkema)

As a result of the experiment, the polypropylene resin composition of Example 1-1 showed a narrow MWD of less than 2.4 and a high recrystallization temperature of 120°C or more.

<Fiber and non-woven fabric manufacturing>

Example 2-1

A melt blown nonwoven fabric was manufactured by performing a melt blowing process using the polypropylene resin composition prepared in Example 1-1.

See Bresee, R.R. and Qureshi, U.A. The resin was extruded into a microfiber web by a process similar to that described in "Influence of Processing Conditions on Melt Blown Web Structure. 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 0.15 pi. With one exception, see Bresee, R.R. and Qureshi, U.A. The pellets were extruded into a microfiber web by a process similar to that described in "Influence of Processing onditions on Melt Blown Web Structure. Part 1-DCD," International Nonwovens Journal, 13(1) 49-55 (2004).

The melt temperature was 235°C, the screw speed was 20 rpm, the die was maintained at 235°C, the primary air (hot air) temperature and pressure were 300°C and 3 psi, respectively, and the polymer throughput rate was 2 kg/hr. , the collector/die distance was 20 cm.

Examples 2-2 to 2-8

An ultrafine fiber web was manufactured in the same manner as in Example 2-1, except that it was carried out under the conditions shown in Table 3 below.

Comparative Examples 2-1 to 2-13

The polypropylene resin composition prepared in Example 1-1 was used, and the melt spinning process was performed under the spinning conditions shown in Table 3 below, except that the same method as in Example 2-1 was performed, A microfiber web was prepared.

Comparative Examples 2-14 to 2-19

The polypropylene resin composition prepared in Comparative Example 1-1 was used, and the melt spinning process was carried out under the spinning conditions shown in Table 3 below, in the same manner as in Example 2-1. A microfiber web was prepared.

Comparative Examples 2-20 to 2-25

The polypropylene resin composition prepared in Comparative Example 1-2 was used, and the melt spinning process was performed under the spinning conditions shown in Table 3 below. A microfiber web was prepared.

Test example 2

The melt blown nonwoven fabrics prepared in the above examples and comparative examples were evaluated for physical properties in the following manner, and the results are shown in Tables 3 to 5 below.

(1) Basis weight of nonwoven fabric (gsm; g/m ² )

The weight of the manufactured nonwoven fabric was measured, and the weight of the nonwoven fabric per unit area was calculated as basis weight.

(2) Radiation stability

During the manufacture of melt blown nonwoven fabric, spinning stability was evaluated according to the following criteria from the presence or absence of fiber fly and single yarn occurrence.

O: Excellent spinning stability as no fiber fly or single yarn occurs

X: If fiber fly or single yarn occurs, spinning stability is poor.

(3) Whether fiber fly occurs or not

During the manufacture of melt blown nonwoven fabric, the occurrence of fiber fly was visually checked and evaluated as O or X depending on the occurrence of fiber fly.

O: Fiber fly occurs

X: No fiber fly occurs

(4) Average diameter (㎛) and standard deviation (STD) of the fiber (㎛)

Measure the diameter of the fibers included in the nonwoven fabric using an analysis device FESEM (HITACHI S-4800), check the average diameter of the fibers from the average value of the measured values, and check the deviation of the fiber diameter from the standard deviation value (STD). did.

(5) mean pore diameter (㎛)

The diameter of the pores included in the nonwoven fabric was measured using an analysis device FESEM (HITACHI S-4800) and expressed as the average value of the measured values.

(6) bulkiness (mm) and density (g/cm ³ )

The thickness of the nonwoven fabric was measured using a digital thickness gauge under the condition of a nonwoven fabric basis weight of 20 gsm, and the average value was expressed as bulkiness.

In addition, the density of the nonwoven fabric was calculated from the basis weight of the nonwoven fabric and the measured thickness value.

(8) Differential pressure (Kpa)

The differential pressure was measured using a filter tester (model name: 8130A, manufactured by TSI) in accordance with US 42 CFR Part 84.

Specifically, the differential pressure applied to the nonwoven fabric was measured when NaCl solution (concentration ≤ 200 mg/m ³ ) was passed through at a flow rate of 85 ± 4 L/min.

Example No. 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 Polypropylene resin composition Example 1-1
Melting temperature (℃) 240 240 240 240 250 250 250 250 Die temperature (℃) 240 240 240 240 250 250 250 250 Air temperature (℃) 290 290 310 310 290 290 310 310 air pressure (pis) 3.0 4.0 3.0 4.0 3.0 4.0 3.0 4.0 DCD*(cm) 20 20 20 20 20 20 20 20 Nonwoven basis weight
(gsm) 20 20 20 20 20 20 20 20 Radiation stability O O O O O O O O Whether or not a fly occurs X X X X X X X X Fiber average diameter (㎛) 1.97 1.81 1.66 1.51 1.32 1.25 1.18 1.13 STD (㎛) 0.48 0.48 0.49 0.50 0.53 0.57 0.58 0.60 Average pore diameter (㎛) 10.1 10.3 10.7 11.0 11.5 11.9 12.2 12.8 Bulkiness (mm) 0.106 0.108 0.118 0.123 0.132 0.135 0.137 0.139 density
(g/ ^cm3 ) 0.1887 0.1852 0.1695 0.1626 0.1515 0.1481 0.1460 0.1439 foreclosure 0.049 0.047 0.044 0.040 0.035 0.033 0.031 0.031

Comparative Example No. 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9 2-10 2-11 2-12 2-13 Polypropylene resin composition Example 1-1 Melting temperature (℃) 230 240 240 240 240 240 240 250 250 250 250 250 250 Die temperature (℃) 230 240 240 240 240 240 240 250 250 250 250 250 250 Air temperature (℃) 320 280 290 290 310 310 320 280 290 290 310 310 320 Air pressure (pis) 5.0 6.0 2.0 5.0 2.0 5.0 4.0 5.0 2.0 5.0 2.0 5.0 3.0 DCD*(cm) 20 20 20 20 20 20 20 20 20 20 20 20 20 Nonwoven basis weight (gsm) 20 20 20 20 20 20 20 20 20 20 20 20 20 Radiation stability X X O X O X X X O X O X X Whether or not a fly occurs O O X O X O O O X O X O O Fiber average diameter (㎛) 2.31 2.30 2.21 1.78 2.15 1.49 1.43 1.53 2.08 1.19 2.01 1.11 1.13 STD (㎛) 0.47 0.46 0.47 0.49 0.43 0.62 0.61 0.60 0.52 0.58 0.57 0.64 0.61 Average pore diameter (㎛) 9.7 9.7 9.8 9.8 9.9 9.7 9.6 9.9 9.8 9.8 9.9 9.7 9.7 Bulkiness (mm) 0.090 0.091 0.095 0.099 0.095 0.099 0.098 0.098 0.098 0.095 0.099 0.093 0.094 Density (g/cm ³ ) 0.2222 0.2198 0.2105 0.2020 0.2105 0.2020 0.2041 0.2041 0.2041 0.2105 0.2020 0.2151 0.2128 Differential pressure (KPa) 0.053 0.053 0.051 0.052 0.051 0.053 0.053 0.052 0.050 0.051 0.051 0.054 0.055

Comparative Example No. 2-14 2-15 2-16 2-17 2-18 2-19 2-20 2-21 2-22 2-23 2-24 2-25 Polypropylene resin composition Comparative Example 1-1 Comparative Example 1-2 Melting temperature (℃) 230 230 240 240 240 250 230 230 240 240 250 250 Die temperature (℃) 230 230 240 240 240 250 230 230 240 240 250 250 Air temperature (℃) 290 310 310 310 320 310 290 310 310 320 310 310 Air pressure (pis) 5.0 4.0 3.0 4.0 3.0 3.0 5.0 4.0 4.0 3.0 3.0 4.0 DCD*(cm) 20 20 20 20 20 20 20 20 20 20 20 20 Nonwoven basis weight (gsm) 20 20 20 20 20 20 20 20 20 20 20 20 Radiation stability X O O X X X X O O X X X Whether or not a fly occurs O X X O O O O X X O O O Fiber average diameter (㎛) 2.40 2.31 1.54 1.46 1.35 1.06 2.47 2.43 1.53 1.40 1.14 1.13 STD (㎛) 0.53 0.55 0.61 0.66 0.69 0.73 0.52 0.46 0.52 0.65 0.58 0.60 Average pore diameter (㎛) 9.4 9.6 10.5 10.9 10.8 10.8 9.3 9.7 10.5 10.5 10.7 10.8 Bulkiness (mm) 0.089 0.091 0.096 0.098 0.97 0.097 0.088 0.077 0.079 0.096 0.079 0.079 Density (g/cm ³ ) 0.2247 0.2198 0.2083 0.2041 0.2062 0.2062 0.2273 0.2597 0.2532 0.2083 0.2532 0.2532 Differential pressure (KPa) 0.055 0.054 0.054 0.053 0.054 0.052 0.056 0.061 0.059 0.055 0.058 0.058

In Tables 3 to 5 above, DCD is the distance between the melt die and the collector.

As a result of the experiment, in the case of the example, as the melt temperature, primary air temperature, and pressure increased, the fineness decreased, the pore size increased, and the bulkiness increased, and as a result, the differential pressure was improved.

On the other hand, in the case of Comparative Example 2-1, the melting temperature was low and the fineness was thick, so there was no effect of improving the differential pressure. In addition, in the case of Comparative Examples 2-2 to 2-13, the fineness increased, flies occurred due to increased spinning instability, and there was no effect of improving differential pressure. In addition, in the case of Comparative Examples 2-14 to 2-19, fine fiberization is easy due to the wide molecular weight distribution of homopolypropylene manufactured using the Ziegler-Natta catalyst, but spinning stability is reduced and fiber thickness deviation increases, resulting in self-binding. This happened.

In addition, in the case of Comparative Examples 2-20 to 2-25 containing homopolypropylene prepared using the metallocene catalyst of Synthesis Example 2, spinning stability is good due to narrow MWD, but self-binding between fibers due to high Trc. This happened.

Claims (19)

Contains fiber containing polypropylene-based resin,
The polypropylene-based resin includes homopolypropylene that satisfies the conditions a1) to a3) below,
A polypropylene-based nonwoven fabric with a bulkiness of 0.1 mm or more and a differential pressure of 0.05 KPa or less under the condition of a non-woven basis weight of 20 gsm:
a1) Recrystallization temperature (Trc) 120℃ or higher
a2) Molecular weight distribution: 2.4 or less
a3) Melting point (Tm) 150 to 160°C
According to paragraph 1,
The homopolypropylene is a nonwoven fabric having a recrystallization temperature of 120.5 to 140°C, a molecular weight distribution of 2 to 2.3, and a melting point of 155 to 160°C.
According to paragraph 1,
The polypropylene-based resin is a non-woven fabric further comprising a phenol-based antioxidant and a lubricant.
According to paragraph 3,
The phenolic antioxidants include tetrakis (methylene (3,5-di-t-butyl-4-hydroxy) hydrosilylate), 1,3,5-trimethyl-tris (3,5-di-t-butyl) -4-hydroxybenzene), and pentaerythritol tetrakis (3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate). And, a nonwoven fabric included in the polypropylene-based resin in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the homo polypropylene.
According to paragraph 3,
The lubricant includes at least one selected from the group consisting of calcium stearate, aluminum para-tertiary butyl benzoic acid, sodium benzoic acid, and calcium benzoic acid, and is used in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the homopolypropylene. A nonwoven fabric contained in the polypropylene-based resin.
According to paragraph 1,
The nonwoven fabric has an average diameter of 2 ㎛ or less and a standard deviation of the fiber diameter of 0.6 ㎛ or less.
According to paragraph 1,
The nonwoven fabric includes pores,
A nonwoven fabric in which the average pore diameter is 10㎛ or more.
According to paragraph 1,
The nonwoven fabric is a nonwoven fabric having a density of 0.01 to 0.2 g/cm ³ under the condition of a nonwoven basis weight of 20 gsm.
According to paragraph 1,
Non-woven fabric, which is a melt-blown non-woven fabric.
Polymerizing a propylene monomer while introducing hydrogen gas in the presence of a catalyst composition containing a transition metal compound represented by the following formula (1) to produce homopolypropylene that satisfies the conditions of a1) to a3) below;
Extruding and pelletizing the composition containing the homo-polypropylene at a temperature of 200 to 250° C. to produce a pellet-shaped polypropylene resin; and
For the polypropylene resin, performing a melt blowing process of injecting air at a temperature of 285 to 315°C at a pressure of 2.5 to 4.5 psi and melt spinning at a melt temperature of 235 to 255°C; comprising the poly according to claim 1. Method for producing propylene-based nonwoven fabric:
a1) Recrystallization temperature (Trc) 120℃ or higher
a2) Molecular weight distribution: 2.4 or less
a3) Melting point (Tm) 150 to 160°C
[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 10,
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 10,
A preparation method wherein the compound of Formula 1 is a compound represented by the following Formula 1a.
[Formula 1a]

According to clause 10,
The catalyst composition further includes a silica carrier and a cocatalyst.
According to clause 10,
The production method wherein the hydrogen gas is supplied in an amount of 700 to 1500 ppmw based on the total weight of the propylene monomer.
According to clause 10,
The composition containing the homopolypropylene further includes a phenol-based antioxidant and a lubricant.
According to clause 10,
The pellet-type polypropylene-based resin has a recrystallization temperature (Trc) of 120°C or more and a molecular weight distribution of 2.4 or less.
According to clause 16,
The pellet-type polypropylene-based resin further satisfies one or more of the conditions b1) to b7) below:
b1) Recrystallization temperature (Trc) 120 to 140°C
b2) Molecular weight distribution: 2.0 to 2.3
b3) Melting point (Tm) 150 to 160°C
b4) Melt index (measured at 230°C and 2.16 kg load according to ASTM D1238) 500 to 1300 g/10min
b5) Xylene soluble content: 0.6% by weight or less
b6) Number average molecular weight: 15,000 to 20,000 g/mol
b7) Weight average molecular weight 30,000 to 50,000 g/mol.
According to clause 10,
The melt blowing process is performed by injecting air at 290 to 310°C at a pressure of 3 to 4 psi into the polypropylene resin and melt spinning at a melt temperature of 240 to 250°C.
According to clause 10,
A manufacturing method wherein the distance between the melt die for melting the polypropylene resin during the melt blowing process and the collector for collecting the fibers of the melt-spun polypropylene resin is 10 to 30 cm.