JPH10226925A - Polypropylene conjugated fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polypropylene conjugated fiber that is useful as a material for nonwoven fabric having excellent tensile strength and heat-sealing properties by using, as the sheath component for conjugated fiber, a polypropylene composition having a high melt tension by subjecting propylene to homo- or -copolymerization using a preliminarily activated catalyst that is prepared by allowing a catalyst for polyolefin production to carry small amounts of the target polymer of homo- or -co-polypropylene and a polyethylene of a specific intrinsic viscosity. SOLUTION: A composition comprising 0.01-5 pts.wt. of polyethylene with an intrinsic viscosity [ηE] measured in tetralin at 135 deg.C, and 100 pts.wt. of a propylene-α-olefin copolymer containing 0.01-20wt.% of an α-olefin other than propylene where the composition has an intrinsic viscosity of 0.2-2.5dl/g measured in tetralin at 135 deg.C and a melting point of 110-150 deg.C is employed as the sheath component and a crystalline polypropylene is used as the core component to carry out conjugate spinning thereby producing the objective conjugated fiber with the ratio of the sheath/the core of 20/80-60/40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conjugate fiber useful for producing a hot roll type nonwoven fabric, and more particularly to a polypropylene-based heat-resistant nonwoven fabric material excellent in tensile strength and heat sealability. The present invention relates to an adhesive composite fiber.

[0002]

2. Description of the Related Art As a heat-adhesive fiber, a core component is polypropylene or polyester and a sheath component is high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, or low-melting polyester. Things are known. Such a conventional sheath-core type heat-bondable fiber is usually formed into a web by a carding process or a sheet by a papermaking process, and then heated to a temperature equal to or higher than the melting point of the sheath component to fuse the contact points of the fibers. Formed on non-woven fabric. As a method of heating and fusing, a hot air bonding method such as a suction band dryer and a suction drum dryer and a hot roll bonding method such as a Yankee dryer and a calender roll are widely used depending on the use of the nonwoven fabric.

[0003] In recent years, as the demand for nonwoven fabrics has increased, there has been an increasing tendency to employ a hot roll bonding method which is relatively inexpensive and has high productivity not only for wet nonwoven fabrics but also for dry nonwoven fabrics.

[0004]

However, the non-woven fabric obtained by using the heat-adhesive fiber as a material by the hot roll method has a problem that the tensile strength is insufficient or the heat sealing property is poor. As a means for remedying this problem, a fiber in which a core component is composed of crystalline polypropylene and a sheath component is mainly composed of propylene has been proposed. However, both the tensile strength and the heat sealing property are insufficient, and the hot roll bonding method is used. There has been a strong demand for the emergence of a polypropylene-based heat-adhesive fiber which is useful as a material for nonwoven fabrics having a high tensile strength and excellent heat-sealing properties.

[0005] In order to solve the above-mentioned conventional problems, the present invention uses a catalyst preactivated by supporting a small amount of polypropylene for the purpose of (co) polymerization and polyethylene having a specific intrinsic viscosity on a catalyst for producing polyolefin. By using the polypropylene composition having a high melt tension obtained by subjecting propylene to the (co) polymerization as the sheath component of the composite fiber, a polypropylene-based composite fiber useful as a nonwoven fabric material having excellent tensile strength and heat sealability is obtained. The purpose is to provide.

[0006]

Means for Solving the Problems In order to achieve the above object, the polypropylene composite fiber of the present invention has a sheath component comprising:
(a) 50 ethylene polymer units or ethylene polymer units
Consisting of an ethylene-olefin copolymer containing at least 135% by weight of intrinsic viscosity [η] measured in tetralin at 135 ° C.
E] is 15 to 100 dl / g.
1 to 5 parts by weight, and (b) propylene-α- containing 0.01 to 20% by weight of an α-olefin other than propylene.
An olefin copolymer having an intrinsic viscosity [ηP] of 0.2 to 2.5 dl / g measured in tetralin at 135 ° C.
Propylene-α-olefin copolymer composition: 1
A polypropylene resin having a melting point of 110 ° C. to 150 ° C., a core component of crystalline polypropylene, and a composite ratio of the core component and the sheath component, wherein the sheath component / core component = 20/80 to 60 / 40 range.

In the above construction, the polypropylene resin has a melt tension (MS) at 230.degree.
It is preferable to have a relationship represented by log (MS)> 4.24 × log [ηT] −1.20 between the intrinsic viscosity [ηT] measured in tetralin at ° C.

[0008] Preferably, the conjugate fiber is used for non-woven fabric production of a hot roll system.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyethylene constituting the component (a) of the polypropylene resin used in the present invention is 135
Intrinsic viscosity [ηE] measured in tetralin at 15 ° C. is 15 to
100 dl / g polyethylene, which is an ethylene homopolymer or an ethylene-olefin random copolymer containing 50% by weight or more of ethylene polymerized units, and preferably contains 70% by weight or more of ethylene homopolymer or ethylene polymerized unit. Suitable are ethylene-olefin random copolymers, more preferably ethylene homopolymers or ethylene-olefin random copolymers containing at least 90% by weight of ethylene polymer units, and these (co) polymers are only one type. Alternatively, two or more kinds may be mixed.

The intrinsic viscosity of the component (a) polyethylene [η
When E] is less than 15 dl / g, the effect of improving the melt tension of the obtained polypropylene resin becomes insufficient, and the upper limit of the intrinsic viscosity [ηE] is not particularly limited,
If the intrinsic viscosity [ηP] of the polypropylene of the component (b) is large, the dispersion of the polyethylene of the component (a) in the polypropylene of the component (b) becomes poor when the composition is formed, resulting in a melt tension. Will not rise. Further, from the viewpoint of manufacturing efficiency, the upper limit is preferably set to about 100 dl / g.

The intrinsic viscosity of the component (a) polyethylene [η
E] is 15 to 100 dl / g, preferably 17 to 50 d / g.
1 / g. In addition, it is necessary to increase the intrinsic viscosity [ηE] of the component (a) polyethylene in tetralin at 135 ° C. to 15 dl / g.
Ethylene polymerized unit is 50% by weight from the viewpoint of increasing the molecular weight
It is preferable that it is above.

The olefin other than ethylene copolymerized with the ethylene constituting the component (a) polyethylene is not particularly limited, but an olefin having 3 to 12 carbon atoms is preferably used.

Specifically, propylene, 1-butene, 1
-Pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, 3-methyl-1-pentene, and the like. These olefins are not limited to one kind, and may be two or more kinds. Is also good.

The density of the polyethylene as the component (a) is not particularly limited, but is specifically 0.880 to 0.8.
Those having about 980 g / cm ³ are preferable. The propylene-α-olefin copolymer (b) constituting the polypropylene resin used in the present invention has an intrinsic viscosity [ηP] of 0.2 to 2.5 measured in tetralin at 135 ° C.
dl / g α-olefin other than propylene
It is a propylene-α-olefin copolymer containing up to 20% by weight.

The intrinsic viscosity [ηP] of the propylene-α-olefin copolymer (b) is 0.2 to 2.5 dl / g.
Is preferred from the viewpoint of processability such as spinnability. More preferably, it is 1.0 to 1.8 dl / g.

The olefin other than propylene copolymerized with propylene constituting the propylene-α-olefin copolymer of the component (b) is not particularly limited, but an olefin having 2 to 12 carbon atoms is preferably used. Specifically, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-
Examples thereof include pentene and 3-methyl-1-pentene. These olefins may be used alone or in combination of two or more.

The polypropylene resin used in the present invention contains 0.01 to 5 parts by weight, preferably 0.02 to 2 parts by weight, more preferably 0.05 to 1 part by weight of the polyethylene (a). b) Component propylene-α-
It consists of 100 parts by weight of the olefin copolymer.

If the polyethylene of component (a) is less than 0.01 part by weight, the effect of improving the melt tension of the obtained polypropylene resin is small, and if it exceeds 5 parts by weight, the effect is saturated and no further effect can be expected. This is not preferred because the homogeneity of the obtained polypropylene resin may be impaired.

The melt tension of the polypropylene resin used in the present invention is a melt tension (MS) at 230 ° C. and 135.
It is preferable that the intrinsic viscosity [ηT] measured in tetralin at a temperature represented by log (MS)> 4.24 log [ηT] -1.20. The upper limit of the relational expression is not particularly limited, but if the melt tension is too high, processability such as spinnability deteriorates.
4.24 × log [ηT] +0.50> log (MS)
> 4.24 × log [ηT] −1.05, more preferably 4.24 × log [ηT] +0.24> log (M
S)> 4.24 × log [ηT] −1.05, most preferably 4.24 × log [ηT] +0.24> log
(MS)> 4.24 × log [ηT] −0.93.

Here, the melt tension at 230 ° C. (M
S): Using a melt tension tester type 2 (manufactured by Toyo Seiki Seisaku-sho, Ltd.), melt the polypropylene resin at a temperature of 230 ° C at a piston drop speed of 20 mm / min from an orifice having a hole of 2.095 mm in diameter and 20 mm in length. Is a value (unit: cN) obtained by measuring the tension of the strand-like polypropylene resin when the molten resin is extruded in the form of a strand into the atmosphere at 23 ° C. and the strand is taken off at a speed of 3.14 m / min.

The melting point of the polypropylene resin used in the present invention is preferably in the range of 110 to 150 ° C.
If the melting point is higher than 150 ° C., the obtained fiber becomes insufficient in heat adhesion, and the tensile strength and heat sealability of the obtained nonwoven fabric are undesirably reduced. Melting point 11
If the temperature is lower than 0 ° C., the surface friction coefficient of the obtained fiber becomes high, which causes a problem that the processability of the nonwoven fabric such as a card process is deteriorated.

The melting point was measured in a nitrogen atmosphere using a DSC7 (Perkin Elmer) differential scanning calorimeter in a nitrogen atmosphere.
0mg sample from 20 ℃ to 230 ℃ 20 ℃ / min
The temperature is raised under the following conditions. Next, after maintaining at 230 ° C. for 10 minutes, the temperature is lowered to −20 ° C. at a rate of 5 ° C./min. After holding at -20 ° C for 10 minutes,
/ Min is a value obtained by measuring the peak temperature of an endothermic curve obtained by increasing the temperature at a rate of / min.

As the method for producing the polypropylene resin of the present invention, any production method may be adopted as long as the melt tension of the polypropylene resin falls within the above range.
In the presence of a catalyst preactivated by ethylene or ethylene and another olefin described in detail below, propylene or propylene and another olefin
It can be easily produced by employing this method of polymerizing.

As used herein, the term "pre-activation" refers to the activity of the high molecular weight catalyst of the polyolefin production, which is determined in advance of the main (co) polymerization of propylene or propylene with other olefins. Pre-activation of ethylene or ethylene and other olefins in the presence of a polyolefin production catalyst (co)
It is carried out by polymerizing and supporting on a catalyst.

The preactivated catalyst preferably used in the present invention is a catalyst component of a transition metal compound containing at least a titanium compound, or 0.01 to 1,000 per mole of a transition metal atom.
Periodic Table of Mole (1991 version), Groups 1 and 2, 12
Organometallic compound (AL1) of a metal selected from the group consisting of metals belonging to Group 13 and Group 13, and 0 to 500 moles of an electron donor (E
A) a polyolefin-producing catalyst comprising the combination of 1), and an intrinsic viscosity [ηB] of less than 15 dl / g measured in tetraline at 135 ° C. of 0.01 to 100 g per 1 g of the transition metal compound component supported on the catalyst. Polypropylene (B) for the purpose of main (co) polymerization, and 0.01 to 5,0 per 1 g of the transition metal compound catalyst component
In the preactivated catalyst comprising polyethylene (A) having an intrinsic viscosity [ηA] of 15 to 100 dl / g as measured in 00 g of tetralin at 135 ° C., it is proposed as a transition metal compound catalyst component for polyolefin production. Any of the known catalyst components containing a transition metal compound catalyst component containing at least a titanium compound as a main component can be used. Among them, a titanium-containing solid catalyst is preferably used for industrial production.

As the titanium-containing solid catalyst component, a titanium-containing solid catalyst component containing a titanium trichloride composition as a main component (JP-B-56-3356, JP-B-59-2857)
No. 3, JP-B-63-66323, and the like, and a titanium-containing supported catalyst component in which titanium tetrachloride is supported on a magnesium compound and titanium, magnesium, halogen, and an electron donor are essential components (Japanese Patent Application Laid-Open No. Sho 62-63). -10481
0, Japanese Patent Application Laid-Open No. 62-104811, Japanese Patent Application Laid-Open
JP-A-2-104812, JP-A-57-63310, JP-A-57-63311, JP-A-58-830
No. 06, Japanese Patent Application Laid-Open No. 58-138712, etc.), and any of these can be used.

As the organometallic compound (AL1), Periodic Table (1991 edition), Group 1, Group 2, Group 12, and Group 1
A compound having an organic group of a metal selected from the group consisting of metals belonging to Group 3, such as an organolithium compound, an organosodium compound, an organomagnesium compound, an organozinc compound, an organoaluminum compound, and the like; Can be used in combination with

In particular, the general formula is AlR ¹ _p R ² _q X
_{3- (p + q)} (wherein, R ¹ and R ² are the same or different of a hydrocarbon group such as an alkyl group, a cycloalkyl group and an aryl group and an alkoxy group, X represents a halogen atom,
p and q represent a positive number of 0 <p + q ≦ 3), and an organoaluminum compound represented by the following formula (1) can be preferably used.

Specific examples of the organoaluminum compound include triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, tri-i-aluminum.
Trialkyl aluminum such as butyl aluminum, diethyl aluminum chloride, di-i-butyl aluminum chloride, diethyl aluminum bromide,
Other diethoxy monoethyl aluminums such as dialkyl aluminum monohalides such as diethyl aluminum iodide, dialkyl aluminum hydrides such as diethyl aluminum hydride, alkyl aluminum sesquihalides such as ethyl aluminum sesquichloride, monoalkyl aluminum dihalides such as ethyl aluminum dichloride And the use of trialkylaluminum and dialkylaluminum monohalides is preferred. These organoaluminum compounds can be used alone or in combination of two or more.

The electron donor (E1) is used as needed for the purpose of controlling the production rate and / or stereoregularity of the polyolefin. Electron donor (E1)
Examples thereof include ethers, alcohols, esters, hydrogen sulfide, and organosilicon compounds having a Si—O—C bond in the molecule.

As ethers, dimethyl ether,
Diethyl ether, di-n-propyl ether, di-n
-Butyl ether, di-i-amyl ether, ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, etc., and alcohols such as methanol, ethanol, propanol, butanol, pentonol, hexanol, ethylene glycol, glycerin, etc .; Classes include phenol, cresol, xylenol, ethylphenol, naphthol and the like.

Examples of the esters include methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, methyl toluate, ethyl toluate, methyl anisate,
Monocarboxylic acid esters such as ethyl anisate and propyl anisate, aliphatic polycarboxylic acid esters such as dibutyl maleate and diethyl butyl maleate, diethyl phthalate, di-n-propyl phthalate, mono-phthalate
n-butyl, di-n-butyl phthalate, di-i-phthalate
-Butyl, di-n-heptyl phthalate, di-2 phthalate
Aromatic polycarboxylic acid esters such as -ethylhexyl, di-n-octyl phthalate, diethyl i-phthalate, dipropyl i-phthalate, and dibutyl i-phthalate.

Examples of the organosilicon compound having a Si—O—C bond in the molecule include silanols such as trimethylsilanol, triethylsilanol and triphenylsilanol, trimethylmethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane, Methyltrimethoxysilane, phenyltrimethoxysilane, dimethyldiethoxysilane, di-
i-propyldimethoxysilane, di-i-butyldimethoxysilane, diphenyldiethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, butyltriethoxysilane, phenyltriethoxysilane, cyclopentylmethyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexyl Trimethoxysilane, dicyclohexyldimethoxysilane and the like.

These electron donors can be used alone or as a mixture of two or more. In the preactivated catalyst, polyethylene (A) has an intrinsic viscosity [ηA] of 15 to 10 measured in tetralin at 135 ° C.
0 dl / g, preferably 50 to 50% by weight of ethylene homopolymer or ethylene polymerized unit in the range of 17 to 50 dl / g.
Or more, preferably 70% by weight or more, more preferably 9% by weight.
It is a copolymer of 0% by weight or less of ethylene and an olefin having 3 to 12 carbon atoms, and finally constitutes the polyethylene as the component (a) of the polypropylene resin used in the present invention. Therefore, the intrinsic viscosity [ηE] of the polyethylene (a) and the intrinsic viscosity [ηA] of the polyethylene (A) have a relationship of [ηE] = [ηA].

The amount of the polypropylene (A) supported per gram of the transition metal compound catalyst component is 0.01 to 5,000 g,
Preferably it is 0.05-2,000 g, more preferably 0.1-1,000 g. When the amount supported per 1 g of the transition metal compound catalyst component is less than 0.01 g, the effect of improving the melt tension of the polypropylene resin finally obtained by the main (co) polymerization is insufficient, and when it exceeds 5,000 g, Not only does the improvement of the effect become insignificant,
It is not preferable because the homogeneity of the finally obtained polypropylene resin may deteriorate.

On the other hand, polypropylene (B) has a temperature of 135 ° C.
Has an intrinsic viscosity [ηB] of 15 dl measured in tetralin.
/ G of polypropylene having the same composition as the polypropylene of the component (b) for the purpose of main (co) polymerization, and is finally incorporated as a part of the polypropylene of the component (b) of the polypropylene resin used in the present invention. The polypropylene (B) is a component that imparts dispersibility to the finally obtained polypropylene resin of the polyethylene (A). In this sense, the intrinsic viscosity [ηB] is the intrinsic viscosity [ηA] of the polyethylene (A). And greater than the intrinsic viscosity [ηT] of the finally obtained polypropylene resin.

On the other hand, the supported amount of the polypropylene (B) per gram of the transition metal compound catalyst component is 0.01 to 100.
g, in other words, the range of 0.001 to 1% by weight based on the finally obtained polypropylene resin is suitable. If the amount of the polypropylene (B) supported is small, the dispersibility of the polyethylene (A) in the target polypropylene resin becomes insufficient. If the amount is too large, the dispersibility of the polyethylene (A) in the polypropylene resin becomes saturated. But not
The production efficiency of the preactivated catalyst is reduced.

In the present invention, the preactivation catalyst preferably used is a combination of the above-mentioned catalyst component of a transition metal compound containing at least a titanium compound, an organometallic compound (AL1) and an electron donor (E1) optionally used. In the presence of a catalyst for the production of polyolefins, propylene or propylene for the purpose of (co) polymerization is preliminarily (co) polymerized with other olefins to produce polypropylene (B), and then ethylene or ethylene and other olefins are The polyethylene (A) is produced by pre-activation (co) polymerization, and is produced by a pre-activation treatment in which the transition metal compound catalyst component carries polypropylene (B) and polyethylene (A).

In this preactivation treatment, a transition metal compound catalyst component containing a titanium compound, and 0.01 to 1,000 mol, preferably 0.05 to 500 mol of an organic metal, per 1 mol of the transition metal in the catalyst component. The compound (AL1) and 0 to 500 moles, preferably 0 to 100 moles, of the electron donor (E1) are combined with 1 mole of the transition metal in the catalyst component to be used as a catalyst for producing a polyolefin.

The catalyst for producing polyolefin is used in an amount of 0.001 to 5,000 mmol, preferably 0 to 5,000 mmol, as the transition metal atom in the catalyst component, per liter of the (co) polymerization volume of ethylene or ethylene and other olefins. .
Propylene or a mixture of propylene and propylene with another olefin for the purpose of (co) polymerization in the presence of from 0.01 to 1,000 mmol and in the absence of a solvent or in a solvent up to 100 liters per gram of the transition metal compound catalyst component.
The mixture is supplied with 0.01 to 500 g and preliminarily (co) polymerized to produce 0.01 to 100 g of polypropylene (B) per 1 g of the transition metal compound catalyst component, and then 0.01 g of ethylene or a mixture of ethylene and other olefins ~ 1
000 g is supplied and pre-activated (co) polymerized, and 0.01 to 5,000 per 1 g of the transition metal compound catalyst component.
By producing g of polyethylene (A), the transition metal compound catalyst component is coated and supported with polypropylene (B) and polyethylene (A).

In the present specification, the term “polymerization volume” refers to the volume of the liquid phase portion in the polymerization vessel in the case of liquid phase polymerization.
In the case of gas phase polymerization, it means the volume of the gas phase portion in the polymerization vessel. The amount of the transition metal compound catalyst component used is preferably in the above range in order to maintain an efficient and controlled (co) polymerization reaction rate of propylene. If the amount of the organometallic compound (AL1) is too small, the (co) polymerization reaction rate becomes too slow, and if the amount is too large, a corresponding increase in the (co) polymerization reaction rate cannot be expected,
It is not preferable because the organometallic compound (AL1) remains in the finally obtained polypropylene composition. Furthermore, if the amount of the electron donor (E1) is too large,
The (co) polymerization reaction rate decreases. If the amount of the solvent used is too large, not only a large reaction vessel is required, but also it is difficult to efficiently control and maintain the (co) polymerization reaction rate.

The preactivation treatment includes, for example, aliphatic hydrocarbons such as butane, pentane, hexane, heptane, octane, isooctane, decane and dodecane; alicyclic hydrocarbons such as cyclopentane, cyclohexane and methylcyclohexane; The reaction can be carried out in a liquid phase using an aromatic hydrocarbon such as xylene or ethylbenzene, an inert solvent such as a gasoline fraction or a hydrogenated diesel oil fraction, or an olefin itself as a solvent. It is also possible to do it in phase.

The pre-activation treatment may be carried out in the presence of hydrogen, but the intrinsic viscosity [ηA] is 15 to 100.
In order to produce a dl / g high molecular weight polyethylene (A), it is preferable not to use hydrogen.

In the preactivation treatment, the conditions for the preliminary (co) polymerization of propylene or a mixture of propylene and another olefin for the purpose of the main (co) polymerization are as follows. 01g
Any condition may be used as long as it produces １００100 g, usually -40 ° C.
It is carried out at a temperature of １００100 ° C. and a pressure of 0.1 MPa to 5 MPa for 1 minute to 24 hours. The pre-activation (co) polymerization conditions for ethylene or a mixture of ethylene and another olefin are as follows: polyethylene (A) is used in an amount of 0.01 to 5,000 g, preferably 0.05 to 2, per gram of the transition metal compound catalyst component. 000 g, more preferably 0.1 g
There is no particular limitation as long as the condition is such that it is produced in an amount of up to 1,000 g, usually -40 to 40C, preferably -4.
Under a relatively low temperature of about 0 ° C. to 30 ° C., more preferably about −40 ° C. to 20 ° C., 0.1 MPa to 5 MPa, preferably 0.2 MPa to 5 MPa, particularly preferably 0.3 MPa.
Under a pressure of a to 5 MPa, it is 1 minute to 24 hours, preferably 5 minutes to 18 hours, particularly preferably 10 minutes to 12 hours.

Further, after the preactivation treatment, propylene or a mixture of propylene and other olefins for the purpose of main (co) polymerization is used for the purpose of suppressing a decrease in main (co) polymerization activity due to the preactivation process. By addition of from 0.01 to 10 per gram of the transition metal compound catalyst component.
The reaction may be performed with a reaction amount of 0 g of polypropylene (C).
In this case, the organometallic compound (AL1) and the electron donor (E
1), the solvent, and the amount of propylene or a mixture of propylene and other olefins can be used in the same range as in the preactivated polymerization using ethylene or a mixture of ethylene and other olefins. 0.005 to 10 mol, preferably 0.1 to 10 mol per mol.
It is preferably carried out in the presence of from 01 to 5 mol of electron donor. The reaction is carried out at a temperature of -40 to 100 ° C and a pressure of 0.1 to 5 MPa for 1 minute to 24 hours.

The organometallic compound (A) used for the addition polymerization
L1), the electron donor (E1), and the type of the solvent,
The same ones as those used in the preactivated polymerization using ethylene or a mixture of ethylene and other olefins can be used, and those having the same composition as the purpose of the present (co) polymerization can be used for propylene or a mixture of propylene and other olefins. .

The intrinsic viscosity [ηC] of the polypropylene produced by the addition polymerization is the intrinsic viscosity [η] of the polyethylene (A).
A] and is finally incorporated as a part of the polypropylene of the component (b) after the main (co) polymerization.

The preactivation catalyst may be used as it is or as an olefin main (co) polymerization catalyst further containing an additional organometallic compound (AL2) and an electron donor (E2).
2 to 12 carbon atoms for obtaining the desired polypropylene resin
Can be used for the main (co) polymerization of olefins.

The olefin main (co) polymerization catalyst may be any one of the preactivated catalyst and the transition metal atom 1 in the preactivated catalyst.
The sum of the organometallic compound (AL2) and the organometallic compound (AL1) in the activation catalyst per mole (AL1 + AL2)
0.05 to 3,000 mol, preferably 0.1 to 1,
The electron donor (E2) and the electron donor (E1) in the preactivated catalyst in total (E1 + E2) are 0 to 5,000 mol, preferably 0,000 mol, and 1 mol of the transition metal atom in the activated catalyst. It consists of 0-3,000 moles.

The content of the organometallic compound (AL1 + AL
If (2) is too small, the (co) polymerization reaction rate in the main (co) polymerization of propylene or propylene and other olefins is too slow, while if it is too large, the (co) polymerization reaction rate is so high as to be expected. No increase is observed, which is not only inefficient, but also undesirably, since the organometallic compound residue remaining in the finally obtained polypropylene composition increases. Further, the content of the electron donor (E1 + E
When 2) is excessive, the (co) polymerization reaction rate is significantly reduced.

The types of the organometallic compound (AL2) and the electron donor (E2) which are additionally used as necessary for the olefin main (co) polymerization catalyst are as described above for the organometallic compound (AL1) and the electron donor. The same one as (E1) can be used. One type may be used alone, or two or more types may be used in combination. Further, they may be the same or different from those used in the pre-activation treatment.

The catalyst for the olefin main (co) polymerization may be a solvent present in the preactivated catalyst, an unreacted olefin,
Organometallic compound (AL1) and electron donor (E1)
And the like, or a suspension obtained by adding a solvent to the granules obtained by filtering or decanting, and an additional organometallic compound (AL2) and, if desired, an electron donor (E2). Or a suspension obtained by adding a solvent to a granular material or a granular material obtained by removing an existing solvent and unreacted olefin by evaporation under reduced pressure or an inert gas stream or the like. And, if desired, an organometallic compound (AL2) and an electron donor (E2).

In the method for producing the polypropylene resin used in the present invention, the amount of the preactivated catalyst or the catalyst for the main (co) polymerization of the olefin is determined based on the amount of transition metal atoms in the preactivated catalyst per liter of polymerization volume. Convert,
0.001 to 1,000 mmol, preferably 0.00
Use 5-500 mmol. By setting the amount of the transition metal compound catalyst component in the above range, it is possible to maintain an efficient and controlled (co) polymerization reaction rate of propylene or a mixture of propylene and a composition olefin.

For the main (co) polymerization of the polypropylene resin used in the present invention, a known olefin (co) polymerization process can be used as the polymerization process. Specifically, propane, butane, pentane, hexane, heptane , Octane, isooctane, decane, dodecane and other aliphatic hydrocarbons, cyclopentane, cyclohexane, methylcyclohexane and other alicyclic hydrocarbons, toluene, xylene, ethylbenzene and other aromatic hydrocarbons, as well as gasoline fractions and hydrogenation A slurry polymerization method in which olefin is (co) polymerized in an inert solvent such as diesel oil fraction, a bulk polymerization method in which olefin itself is used as a solvent, and a gas phase in which (co) polymerization of olefin is performed in a gas phase Liquid phase polymerization in which the polyolefin produced by the polymerization method and (co) polymerization is liquid, or May be used polymerization process that combines two or more processes.

When using any of the above polymerization processes, the polymerization conditions include a polymerization temperature of 20 to 120 ° C., preferably 30 to 100 ° C., and particularly preferably 40 to 100 ° C.
° C, the polymerization pressure is 0.1 to 5 MPa, preferably in the range of 0.3 to 5 MPa, continuous, semi-continuous,
Alternatively, the polymerization time in the range of about 5 minutes to 24 hours is employed in a batch manner. By adopting the above polymerization conditions, the polypropylene as the component (b) can be produced with high efficiency and a controlled reaction rate.

In a preferred embodiment of the method for producing a polypropylene resin used in the present invention, the intrinsic viscosity of the propylene-α-olefin copolymer (b) produced in the (co) polymerization is from 0.2 to 2. When it is in the range of 5 dl / g, it is particularly suitable as a component for a conjugate fiber, and polyethylene (A) derived from the preactivated catalyst used in the obtained polypropylene composition is 0.0
The polymerization conditions are selected so as to be in the range of 1 to 5% by weight.
In addition, similarly to the known olefin polymerization method, the molecular weight of the (co) polymer obtained by using hydrogen during the polymerization can be adjusted.

After the completion of the (co) polymerization, if necessary, a post-treatment step such as a known catalyst deactivation treatment step, catalyst residue removal step, and drying step is carried out to obtain a desired polypropylene composition having a high melt tension. Is finally obtained.

[0058] olefin (co) polymer composition obtained, G'frequency omega = 10 ⁰ storage modulus o'clock melt ^{230 ℃ (ω = 10 0)} , storage at frequency omega = 10 ^-2 When the elastic modulus is G ′ (ω = 10 ⁻² ), log (G ′ (ω = 10 ⁰ )) − log (G ′ (ω = 1
0 ⁻² )) <2.

Further, the olefin (co) polymer composition comprises:
4 × 10 ^-1 at 190 ° C, 230 ° C, and 250 ° C (se
The first normal stress difference N _{1 at} a shear rate of c ⁻¹ ) preferably has a relationship represented by log (N ₁ )> − log (MFR) +5 (where MFR is a melt flow rate).

Further, the olefin (co) polymer composition comprises:
At 190 ° C. and 250 ° C., the first normal stress difference N ₁ (190 ° C.) and N _{1 at} a shear rate of 4 × 10 ⁻¹ (sec ⁻¹ )
(250 ° C.), [N ₁ (190 ° C.) − N ₁ (250 ° C.)] / N ₁ (190 ° C.)
° C) <0.6.

Further, the olefin (co) polymer composition comprises:
At 190 ° C. and 250 ° C., the melt tension MS (190 ° C.) and MS (25 ° C.) at a shear rate of 3 × 10 ⁻¹ (sec ⁻¹ ).
0 [deg.] C.), [MS (190 [deg.] C.)-MS (250
° C)] / MS (190 ° C) <3.1.

Further, the olefin (co) polymer composition comprises:
T = 1 under the condition that the strain of the melt at 230 ° C. is 500%
The relaxation elastic modulus of 0 (sec) is G (t = 10), and t = 30
When the relaxation elastic modulus of 0 (sec) is G (t = 300), [G (t = 10) −G (t = 300)] / G (t = 1
0) It is preferable to have a relationship represented by <1.

The above-mentioned olefin (co) polymer composition, for example, polypropylene resin, usually contains various additives added to the thermoplastic resin, for example, antioxidants, antistatic agents,
Anti-blocking agent, lubricant, neutralizer, UV absorber,
Light stabilizers, molecular weight depressants and the like can be appropriately compounded as long as the effects of the present invention are not impaired.

In the present invention, the crystalline polypropylene used as the core component of the composite fiber is a crystalline polypropylene generally used for fibers. The conjugate fiber of the present invention can be produced by using the above-mentioned sheath-core composite spinning apparatus and drawing apparatus with the above-mentioned sheath component and core component. Further, a production method that does not perform stretching, such as a spun bond method or a melt blow method, may be used.

The reason why the composite weight ratio of the sheath component and the core component (sheath component / core component) is limited to 20/80 to 60/40 is as follows.
If the sheath component is less than 20%, the thermal adhesion of the obtained fiber is reduced, and a nonwoven fabric using the same cannot obtain sufficient tensile strength and heat sealability.
%, The thermal adhesiveness is sufficient, but the web shrinkage increases, and the dimensional stability decreases.

The relationship between the sheath component and the core component may be either concentric or eccentric, but the concentric type is preferred because of less shrinkage during heat treatment. Usually, breakage of the nonwoven fabric obtained by the hot roll bonding method is caused by breakage of bonding points of fibers. Therefore, the tensile strength of the nonwoven fabric depends on the strength of the fiber bonding point.

In the heat-adhesive conjugate fiber of the present invention, the sheath component forming the bonding point of the fiber at the time of forming the nonwoven fabric has a large melt tension,
It is considered that this leads to the high strength of the bonding point. Since the sheath component and the core component of the heat-adhesive conjugate fiber of the present invention are both polymers mainly composed of polypropylene, the affinity between the sheath component and the core component is extremely large, and peeling at the boundary surface between the sheath and the core hardly occurs. Therefore, not only can a high strength, high heat sealing nonwoven fabric be easily obtained by the hot roll method, but it also has thermal adhesiveness to other materials such as rayon and pulp. After cutting into staples of fiber length, mixing and forming a web, and then heat bonding, a nonwoven fabric having a sufficient tensile strength can be obtained.

[0068]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The evaluation method used in Examples and Comparative Examples was as follows. (1) Intrinsic viscosity [η]: The intrinsic viscosity measured in tetralin at 135 ° C. is a value (unit: dl / g) measured by an Ostwald viscometer: (manufactured by Mitsui Toatsu Chemicals). (2) Melt tension (MS): Value measured by melt tension tester type 2 (manufactured by Toyo Seiki Seisaku-sho, Ltd.) (unit: c)
N) MFR: Based on JIS K6758. (3) Melting point: 10 mg of a sample was measured in a nitrogen atmosphere using a DSC 7 (manufactured by PerkinElmer) differential scanning calorimeter.
The temperature is increased from 0 ° C. to 230 ° C. at a rate of 20 ° C./min. Next, after holding at 230 ° C. for 10 minutes, 5 ° C.
The temperature is lowered to -20 ° C under the condition of / min. Further -20
This is a value obtained by measuring the peak temperature of an endothermic curve obtained by maintaining the temperature at 10 ° C. for 10 minutes and then increasing the temperature at a rate of 20 ° C./min. (4) Tensile strength of nonwoven fabric: A sample staple fiber was formed into a web having a basis weight of about 20 g / m2 using a miniature card machine, and heated to 130 ° C. in a metal roll having a diameter of 165 mm. : Flat roll) at a linear pressure of 20 kg / cm and a speed of 6 m / min to form a nonwoven fabric. 5 cm each in the machine flow direction (hereinafter sometimes abbreviated as MD) and the direction perpendicular thereto (hereinafter sometimes abbreviated as CD) from the obtained nonwoven fabric.
Create a specimen of width, and use a tensile tester to
A value obtained by measuring the tensile strength at 00 mm and a tensile speed of 100 mm / min (unit: kg / 5 cm). (5) Heat sealability: A 5 cm wide test piece cut out from a nonwoven fabric having a weight of about 20 g / m2 made of a polypropylene fiber (2 d / f) was cut out from a nonwoven fabric used for the measurement of the tensile strength of the nonwoven fabric. Length 1 at the tip
cm, 3 kg / cm ² for 3 seconds under pressure
The composite material is thermocompressed at 50 ° C., and is gripped with a tensile tester at a gripping distance of 100 mm and a tensile speed of 100 mm / min.
The value obtained by measuring the peel strength in (unit: kg / 5 cm). (6) Web heat shrinkage: Shrinkage in the MD direction of the web when the sample short fiber is made into a web having a basis weight of about 200 g / m ² by a miniature card machine and subjected to a heat treatment at 145 ° C. for 5 minutes by a hot air circulation dryer. Shows the rate (unit:%).

The polypropylene (PP) used in the examples and comparative examples was prepared as follows. PP1 (1) Preparation of transition metal compound catalyst component Decane 0. 1 in a stainless steel reactor equipped with a stirrer.
3 liters, 48 g of anhydrous magnesium chloride, 170 g of n-butyl orthotitanate and 195 g of 2-ethyl-1-hexanol were mixed, and the mixture was heated to 130 ° C. while stirring.
The mixture was heated for a period of time to dissolve to form a uniform solution. This homogeneous solution was heated to 70 ° C., 18 g of di-i-butyl phthalate was added with stirring, and after 1 hour, 520 g of silicon tetrachloride was added over 2.5 hours to precipitate a solid.
For 1 hour. The solid was separated from the solution and washed with hexane to give a solid product.

The total amount of the solid product was mixed with 1.5 liter of titanium tetrachloride dissolved in 1.5 liter of 1,2-dichloroethane, and 36 g of di-i-butyl phthalate was added. After the reaction, the liquid phase was removed by decantation at the same temperature, and 1.5 l of 1,2-dichloroethane and 1.5 l of titanium tetrachloride were added again. 2.8% by weight of titanium
, A titanium-containing supported catalyst component (transition metal compound catalyst component).

(2) Preparation of Pre-Activated Catalyst After replacing a stainless steel reactor having an inner volume of 5 liters with inclined blades with nitrogen gas, 2.8 liters of n-hexane was added.
Triethyl aluminum (organic metal compound (AL1))
9.0 g of 4 mmol and the titanium-containing supported catalyst component prepared in the preceding paragraph (5.26 mmol in terms of titanium atoms)
After the addition, 20 g of propylene was supplied, and prepolymerization was performed at −2 ° C. for 10 minutes.

Separately, when the polymer produced by the prepolymerization performed under the same conditions was analyzed, 2 g of propylene was converted to polypropylene (B) per 1 g of the titanium-containing supported catalyst component, and the polypropylene (B) was dissolved in tetralin at 135 ° C. Intrinsic viscosity [ηB] measured at 2.8 dl / g
Met.

After the completion of the reaction time, unreacted propylene was discharged to the outside of the reactor, and the gas phase of the reactor was replaced with nitrogen once. Ethylene was continuously supplied to the reactor for 2 hours so that the internal pressure was maintained at 0.59 MPa to perform preactivation.

Separately, the polymer formed by the preactivation polymerization performed under the same conditions was analyzed. As a result, 24 g of the polymer was present per 1 g of the titanium-containing supported catalyst component, and the polymer was measured in tetralin at 135 ° C. The intrinsic viscosity [ηT2] was 31.4 dl / g.

The amount (W2) of polyethylene (A) per 1 g of the titanium-containing supported catalyst component produced by the preactivation polymerization with ethylene is determined by the amount of the polymer produced per 1 g of the titanium-containing supported catalyst component after the preactivation treatment ( WT2) and the amount (W1) of polypropylene (B) produced per gram of the titanium-containing supported catalyst component after the prepolymerization can be obtained by the following equation.

W2 = WT2-W1 The intrinsic viscosity [ηA] of the polyethylene (A) produced by the preactivation polymerization with ethylene is calculated based on the intrinsic viscosity [ηB] of the polypropylene (B) produced by the prepolymerization and the preactivation. It is determined from the intrinsic viscosity [ηT2] of the polymer formed by the treatment according to the following equation.

[ΗA] = ([ηT2] × WT2- [η
B] × W1) / (WT2-W1) = [ηE] The amount of polyethylene (A) produced by preactivation polymerization with ethylene according to the above formula is 22 g per 1 g of the titanium-containing supported catalyst component, and the intrinsic viscosity [ηE] is 34.0 dl /
g.

After the completion of the reaction time, unreacted ethylene is discharged to the outside of the reactor, and the gas phase of the reactor is replaced with nitrogen once, and then diisopropyldimethoxysilane (electron donor (E1)) is introduced into the reactor. After adding 1.6 mmol, 20 g of propylene was supplied, and the mixture was kept at 1 ° C. for 10 minutes to perform addition polymerization after the preactivation treatment.

Separately, the results of the analysis of the polymer formed by the addition polymerization performed under the same conditions show that the intrinsic viscosity of 26 g of the polymer per 1 g of the titanium-containing supported catalyst component was measured in tetralin at 135 ° C. [ΗT3]
Is 29.2 dl / g, and the amount of polypropylene produced by addition polymerization (W
3) was 2 g per 1 g of the titanium-containing supported catalyst component, and the intrinsic viscosity [ηC] was 2.8 dl / g.

After the completion of the reaction time, unreacted propylene is discharged out of the reactor, and the gas phase of the reactor is replaced with nitrogen once.
A preactivated catalyst slurry for the main (co) polymerization was obtained. (3) Production of Polypropylene Composition (Main (Co) polymerization of Propylene) After replacing a stainless steel polymerization vessel equipped with a stirrer with an inner volume of 500 liters with nitrogen, at 20 ° C n-hexane 24
0 liter, 780 mmol of triethylaluminum (organic metal compound (AL2)), 78 mmol of diisopropyldimethoxysilane (electron donor (E2)) and 1/2 of the pre-activated catalyst slurry obtained above were introduced into the polymerization vessel. did. Subsequently, the hydrogen concentration, ethylene concentration and butene-1 concentration relative to the propylene concentration were set to 0.0
8, 0.025 and 0.038.
After the temperature was raised to 60 ° C., the pressure in the gas phase in the polymerization vessel was 0.7
While maintaining 9 MPa, propylene, hydrogen, ethylene and butene-1 were continuously supplied into the polymerization vessel for 2 hours to carry out copolymerization of propylene-α-olefin.

After the elapse of the polymerization time, 1 liter of methanol was introduced into the polymerization vessel, and the catalyst was deactivated at 60 ° C. for 15 minutes. After the unreacted gas was discharged, the solvent was separated and the polymer was dried. Has an intrinsic viscosity [ηT] of 1.67 dl / g.
Of polymer was obtained.

The obtained polymer had a polyethylene (A) content of 0.2 by preactivated polymerization corresponding to the component (a).
5% by weight of a polypropylene resin, and the intrinsic viscosity [ηP] of the propylene-α-olefin copolymer of the component (b)
Was 1.59 dl / g.

(4) Granulation of Polypropylene Resin 0.1 part by weight of 2,6-di-t-butyl-p-cresol as an antioxidant and 0.1 part by weight of calcium stearate were added to 100 parts by weight of the obtained polypropylene resin. One part by weight was blended and stirred and mixed for 1 minute with a Henschel mixer (trade name). The resulting mixture was screwed with a diameter of 40 mm.
And extruded at 230 ° C. to obtain pellets. When various physical properties of the obtained pellet were measured, the MFR was 7.6 g / 10 minutes, the melt tension was 1.3 cN, and the melting point was 140 ° C. Table 1 shows the detailed properties of the obtained polypropylene resin.

After obtaining a titanium-containing supported catalyst component under the same conditions as in PP1, the pre-activated polymerization with ethylene was not carried out.
The propylene-α-olefin copolymer was polymerized under the same conditions as in (1) of P1, to obtain a polypropylene resin. The obtained polypropylene resin was evaluated according to PP1. Table 1 shows properties of the obtained polypropylene resin.

[0085]

[Table 1]

Example 1 PP1 was used as a sheath component.
Melting point 16 with MFR of 8 g / 10 min as core component
A composite ratio of 40/60 (sheath component / core component) and a spinning temperature of 3 ° C. by a composite spinning device equipped with a 0.6 mm diameter nozzle using crystalline polypropylene (homopolymer) at 3 ° C.
The fiber was spun at 10 ° C. and a take-up speed of 900 m / min to obtain a concentric sheath-core composite fiber having a single yarn fineness of 4.2 d / f. Next, the undrawn yarn is drawn at a draw ratio of 2.6 times at a draw temperature of 95 ° C.
After applying mechanical crimping and drying at 80 ° C., the fiber was cut into 38 mm to obtain a conjugate fiber staple.

Example 2 A composite fiber staple was obtained under the same conditions as in Example 1 except that the composite ratio was 60/40.

Comparative Example 1 A composite fiber staple was obtained under the same conditions as in Example 1 except that the sheath component was PP2.

The composite fiber staples obtained in Examples 1 and 2 and Comparative Example 1 were defibrated by a carding machine to form a web, and then a hot roll (heated emboss roll) at 130 ° C. was used. Then, hot roll processing was performed at a linear pressure of 20 kg / cm to form a nonwoven fabric. The basis weight of the obtained nonwoven fabric is 20 g
/ M ² . Table 2 shows the conditions and results of the obtained nonwoven fabric.

[0090]

[Table 2]

As is clear from Table 2, it was confirmed that the products of Examples of the present invention were excellent in tensile strength and heat sealability.

[0092]

The hot rolled nonwoven fabric obtained from the conjugate fiber of the present invention has a good tactile sensation (feel), high strength, and excellent heat sealability. This nonwoven fabric can be used as a surface material of sanitary materials such as disposable diapers and sanitary napkins, or as a medical material such as surgical gowns.

The nonwoven fabric obtained by the wet method using the conjugate fiber of the present invention also has high strength and high heat sealability, so that it is widely used not only in the general paper field but also as a tea bag and other packaging materials. it can.

Claims (3)

[Claims] The sheath component comprises (a) an ethylene homopolymer or an ethylene-olefin copolymer containing at least 50% by weight of ethylene polymerized units, and has an intrinsic viscosity [ηE] measured in tetralin at 135 ° C. 15-100 dl / g
0.01 to 5 parts by weight of polyethylene and (b) 0.01 to 20% by weight of an α-olefin other than propylene
Intrinsic viscosity [η] measured in tetralin at 135 ° C.
P] is 0.2 to 2.5 dl / g.
Olefin copolymer composition: 100 parts by weight, a polypropylene resin having a melting point of 110 ° C. to 150 ° C., a core component of crystalline polypropylene, and a composite ratio of the core component and the sheath component, the sheath component / core Component = 20/8
A polypropylene-based composite fiber having a range of 0 to 60/40. 2. The polypropylene resin has a log tension (MS)> 4.24 × log [ηT] between its melt tension (MS) at 230 ° C. and intrinsic viscosity [ηT] measured in tetralin at 135 ° C. The polypropylene-based composite fiber according to claim 1, which has a relationship represented by -1.20. 3. The polypropylene-based conjugate fiber according to claim 1, wherein the polypropylene-based conjugate fiber is used for producing a non-woven fabric of a hot roll system.