JPH09291415A - Polyethylene super high modulus high strength fiber - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide an ultrahigh elastic modulus and high strength fiber. A viscosity-average molecular weight (M _v) is not less 30 × 10 ⁴ or more, weight average molecular weight (M _w) and number average molecular weight ratio _{(M n) (M w /} M n) is 3 or less An ultrahigh elastic modulus and high strength fiber is obtained from a high molecular weight ethylene homopolymer or a copolymer of ethylene and 0.5 mol% or less of α-olefin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyethylene-based fiber material. More specifically, it is obtained from a high molecular weight ethylene homopolymer having a narrow molecular weight distribution or a copolymer of ethylene and 0.5 mol% or less of α-olefin (hereinafter, these are abbreviated as polyethylene-based polymers). The present invention relates to ultrahigh elastic modulus and high strength fibers.

[0002]

2. Description of the Related Art Conventionally, a high molecular weight polyethylene polymer having a molecular weight of more than 10 × 10 ⁴ has various inorganic magnesium compounds such as magnesium halide, magnesium oxide and magnesium hydroxide as a carrier and titanium or It is produced using a catalyst supporting a transition metal compound such as vanadium. However, the polymerized powder of high-molecular-weight polyethylene-based polymer obtained by these known techniques generally has a small bulk density, the particle size distribution of the powder particles is wide, and fibrils are generated in the powder particles, which are dissolved in a solvent. hard. Among them, the poor solvent solubility is a major obstacle to the production of ultra-high elastic modulus and high-strength fibers using a high-molecular-weight polyethylene-based polymer produced by gel spinning, which is increasing in demand in recent years, For this field, it is one of the technical problems to obtain a polymerized powder which is excellent in solvent solubility even if it has a high molecular weight.

On the other hand, as the name implies, the super high elastic modulus and high strength fiber using a high molecular weight polyethylene polymer has important elastic modulus and fiber breaking strength. Among these, the crystallinity and molecular orientation of the polyethylene-based polymer in the fiber sample are important factors for the elastic modulus. The crystallinity is an important factor because the molecular chains of the coalescence are almost completely uniaxially oriented in the fiber direction. In the case of fiber breaking strength, on the other hand, structural defects at the molecular ends determine its properties. Therefore, the molecular weight is an important factor for the fiber breaking strength, and particularly when the number average molecular weight (M _n ) is small, it is disadvantageous for the fiber breaking strength. In that sense, those having the same weight average molecular weight (M _w ) but having a small number average molecular weight (M _n ), that is, having a wide molecular weight distribution are not preferable in terms of fiber breaking strength. A conventional high molecular weight polyethylene polymer has a broad molecular weight distribution in addition to the above-mentioned poor solubility in a solvent. Therefore, when a larger fiber breaking strength is required, it is difficult to meet the demand. Even with conventional polyethylene-based polymers, the fiber breaking strength can be increased to some extent by increasing the average molecular weight, but in that case, conventional high-molecular-weight polyethylene polymers are more and more solvent soluble. Will be inferior.

[0004]

Therefore, the high-molecular-weight polyethylene-based polymer for ultrahigh-modulus and high-strength fiber has a weight average molecular weight (M _w ) equivalent to that of the conventional high-molecular-weight polyethylene-based polymer, and It has been desired to find a direction for improving the fiber breaking strength.

It is an object of the present invention to provide ultra high modulus high strength fibers having greater fiber breaking strength.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have a specific viscosity average molecular weight and have a remarkably higher molecular weight distribution than the conventional one. It has been found that a narrow high molecular weight ethylene homopolymer or a super high modulus high strength fiber obtained from a copolymer of ethylene and 0.5 mol% or less of α-olefin can solve the problem, The present invention has been completed.

That is, in the present invention, the viscosity average molecular weight (M _v ) is 30 × 10 ⁴ or more, and the weight average molecular weight (M _v
w ) and number average molecular weight (M _n ) ratio (M _w / M _n ) of 3 or less, high molecular weight ethylene homopolymer or ethylene and 0.5 mol% or less of α-olefin The present invention relates to an ultrahigh elastic modulus and high strength fiber obtained from the above copolymer.

Hereinafter, the present invention will be described in detail. The polyethylene-based polymer used for obtaining the polyethylene-based ultra high modulus high-strength fiber of the present invention is a homopolymer of ethylene or ethylene obtained by copolymerization of ethylene and 0.5 mol% or less of α-olefin. -It may be either an α-olefin copolymer or a mixture thereof. Here, the α-olefin has 3 to 20 carbon atoms, and for example, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1
-Heptene, 1-octene, 1-nonene, 1-decene,
1-undecene, 1-dodecene, 1-tridecene, 1-
Tetradecene, 1-pentadecene, 1-hexadecene,
1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, etc. are mentioned, and these 1 type (s) or 2 or more types are used. Among them, propylene, 1-butene, 1-heptene, 1-hexene,
1-octene and the like are preferable.

Here, the α-olefin content is 0.5 mol% or less of the whole copolymer. When the α-olefin content exceeds 0.5 mol%, the crystallinity of the obtained ethylene / α-olefin copolymer is lowered and the elastic modulus of the fiber, which is one of the required performance, is lowered, which is preferable. Absent.

The polyethylene polymer used for obtaining the polyethylene ultra high modulus high strength fiber of the present invention has a viscosity average molecular weight (M _v ) of 30 × 10 ⁴ or more, preferably 50 × 10 ⁴ , More preferably, it is 100 × 10 ⁴ or more. When M _v is less than 30 × 10 ⁴ , the elastic modulus satisfies the performance required for the fiber, but the fiber breaking strength is not sufficient, which is not preferable. Further, when M _v is less than 100 × 10 ⁴ , the fiber breaking strength may not be sufficient depending on the application, so that the obtained ultra-high modulus high-strength fiber is stably used for various applications. _Has an M _v of 100
A so-called ultra-high molecular weight polyethylene-based polymer of × 10 ⁴ or more is particularly preferable.

Further, the polyethylene-based polymer used to obtain the polyethylene-based ultrahigh modulus high-strength fiber of the present invention has a ratio ( _Mw / _Mw ) of the weight average molecular weight ( _Mw ) to the number average molecular weight ( _Mn ). M _n ) is 3 or less. When M _w / M _n is larger than 3, M _n becomes small even if the polyethylene polymer has the same M _w , and the fiber breaking strength of the obtained fiber becomes small, which is not preferable.

The polyethylene-based polymer used to obtain the polyethylene-based ultrahigh elastic modulus and high-strength fiber is, for example, an inorganic compound carrier having the following general formula (1) R ¹ (C ₅ H ₄ ) (C ₄ H _4-m R ² _m C ₅ C ₄ H _4-n R ³ _n ) M ¹ X ₂ (1) [wherein R ¹ is a (C ₅ H ₄ ) group and a (C ₄ H _4-m R 2 ² _m C ₅ C ₄ H
_An aryl group-containing hydrocarbon group, a silanediyl group or a germanediyl group, which crosslinks a _4-n R ³ _n ) group to increase the steric rigidity of the compound represented by the general formula (1), and is a (C ₅ H ₄ ) group. Is a cyclopentadienyl group, and is (C ₄ H _4-m R ² _m C ₅
C ₄ H _4-n R ³ _n ) group is a substituted fluorenyl group, and R ² and R ³ are substituents on the benzo ring portion of the substituted fluorenyl group, which may be the same or different and each have 1 carbon atom.
~ 20 amino group or oxygen-containing hydrocarbon group or halogen, M ¹ is titanium, zirconium or hafnium, X is independently a hydrogen atom, a hydrocarbon group, an amino group having 1 to 20 carbon atoms or oxygen. It is a contained hydrocarbon group or halogen, m is an integer of 0 to 4, n is an integer of 0 to 4, and m + n is 1 or more. ] The metallocene carrying component carrying the metallocene compound represented by the following general formula (2) AlR ⁴ ₃ (2) [In the formula, each R ⁴ is independently a hydrogen atom and a carbon number of 1 to 20.
Is an alkyl group. ] -70-12 using the metallocene carrying | support catalyst which consists of an alkylaluminum compound represented by these, or the metallocene carrying | support catalyst which also consists of water.
Homopolymerization of ethylene, or ethylene and carbon number 3 at a temperature of 0 ° C and a pressure of 0.5 to 100 kg / cm ² · G
Produced with high catalytic activity by copolymerizing ~ 20 alpha-olefins.

Here, the inorganic compound carrier is not particularly limited, but inorganic oxides such as silica, alumina, magnesia, and zeolite, halogen-substituted compounds of the above inorganic oxides,
Boron compound substitution product of the inorganic oxide, inorganic chloride such as magnesium chloride, montmorillonite, saponite,
Examples thereof include clay minerals such as hectorite and modified clays obtained by treating the clay mineral with a compound capable of introducing cations between the clay minerals.

Further, in order to obtain a high molecular weight polyethylene polymer with high catalytic activity, the above-mentioned inorganic compound carrier, metallocene compound and the following general formula (3)

[0015]

Embedded image

And / or the following general formula (4)

[0017]

Embedded image

[In the formula, each R ⁵ is independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an aryl group, an arylalkyl group or an alkylaryl group having 6 to 20 carbon atoms, and q is 2 to 50. Is an integer. ] The metallocene-supported catalyst composed of an aluminoxane represented by the following formula or a metallocene-supported catalyst composed of an alkylaluminum compound further can be used to produce under the same conditions as described above.

The polyethylene polymer used to obtain the ultrahigh elastic modulus and high strength fiber of the present invention is obtained by polymerizing the metallocene-supported catalyst in a solution state, a suspension state or a gas phase state. You can In this case, in order to obtain a polyethylene-based polymer with high catalytic activity and a polyethylene-based polymer with a higher bulk density, the polymerization temperature is -70 to 120 ° C, preferably 0 to
At a temperature of 100 ° C., more preferably 30 to 90 ° C., the pressure during polymerization is 0.5 to 100 kg / cm ² · G, preferably 1 to 80 kg / cm ² · G, and more preferably 5 to
It is 50 kg / cm ² · G.

In the present invention, when the polymerization for obtaining the polyethylene-based polymer is carried out in a solution state or a suspension state, the polymerization solvent may be any organic solvent generally used, and specifically, chloroform may be used. , Halogenated hydrocarbons such as methylene chloride and carbon tetrachloride, propane, n-butane, isobutane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-
Aliphatic hydrocarbons having 3 to 20 carbon atoms such as decane, aromatic hydrocarbons having 6 to 20 carbon atoms such as benzene, toluene, xylene and the like can be used, and further ethylene or α- having 3 to 20 carbon atoms can be used. The olefin itself can also be used as a solvent.

The molecular weight of the polyethylene-based polymer used to obtain the polyethylene-based ultrahigh modulus high-strength fiber of the present invention varies depending on the polymerization conditions such as the polymerization temperature, the kind of metallocene compound or the proportion of the catalyst component used. It can be adjusted by adding hydrogen to the polymerization system.

The polymerized powder of the polyethylene polymer used in the present invention includes, for example, phenol stabilizers, organic phosphite stabilizers, organic thioether stabilizers, stabilizers such as metal salts of higher fatty acids, etc. The stabilizer of the present invention is in a range not impairing the object of the present invention, for example, polyethylene-based polymer 10
It can be added up to about 0.5 parts by weight with respect to 0 parts by weight.

The ultrahigh elastic modulus and high strength fiber in the present invention is
It is manufactured using a polyethylene-based polymer manufactured using the above metallocene-supported catalyst. Examples of the method for producing fibers satisfying the object of the present invention include so-called gel drawing, in which a gel obtained by rapidly cooling a semidilute solution of the above-mentioned polyethylene polymer (polymer concentration of 1% by weight or more) is drawn. Method, or a two-stage stretching combining solid phase coextrusion and tensile stretching from a dried sample of the single crystal aggregate by precipitating a single crystal from a dilute solution of the above-mentioned polyethylene-based polymer (polymer concentration of 0.2% by weight or less) The law is known. Industrially, it is generally manufactured by a process to which a gel stretching method is applied.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Here, various properties of the polyethylene-based polymers used in Examples and Comparative Examples were measured by the following methods.

1. Viscosity average molecular weight (M _v ): Intrinsic viscosity [η] is ASTM D 1601-86 (1990)
Year)) and measured in ortho-dichlorobenzene at 135 ° C. The viscosity average molecular weight (M _v ) was calculated by substituting the intrinsic viscosity [η] into the following formula (5).

[Η] = 5.05 × 10 ⁻⁴ × M _v ^0.693 (5) 2. Weight average molecular weight ( _Mw ), number average molecular weight ( _Mn ): M
_w and M _n were measured by gel permeation chromatography (GPC). Wa as a GPC device
ters 150C ALC / GPC, Tohso Corp. GMH-HR-H (S) was used as the column, the column temperature was set to 145 ° C., and 1- was used as the eluent.
It was measured using chloronaphthalene. Measurement sample is 0.0
The concentration was adjusted to 8 mg / milliliter, and 200 microliter was injected to measure. The calibration curve of the molecular weight is calibrated by a universal calibration method using a polystyrene sample having a known molecular weight (absolute molecular weight = 2600 to 8640000).

[Production of Fiber] Although it is generally industrially produced by a gel spinning method, a fiber is produced by a two-stage drawing method of a dry sample of a single crystal aggregate here. The manufacturing process is as shown below. First, a dilute solution of polyethylene-based polymer in xylene is prepared. The concentration of the solution is 0.
After dissolving at 2% by weight at 135 ° C. for 30 minutes, it was immediately put in an oil bath at 80 ° C. and left as it was for 48 hours to prepare a single crystal suspension of polyethylene polymer. After that, this is filtered using a flat nutche,
After washing with methanol, apply a constant load from above,
Suction filtration was continued. Thereby, a film-shaped single crystal aggregate sample was obtained, and thereafter, vacuum drying was performed at 60 ° C. for 48 hours while applying a load to obtain a dry sample of the single crystal aggregate.

In the first-stage stretching in the two-stage stretching method, a strip-shaped sample having a width of 5 mm is cut out from this film-shaped single crystal aggregate sample, and a cylindrical sample having a diameter of 10 mm made of general high-density polyethylene is vertically cut. A strip sample is also extruded at the same time by sandwiching the sample in half in the direction and extruding these columnar samples. That is, it is a co-extrusion method. The die used for extrusion was such that the draw ratio of the strip-shaped sample was about 6 times, but the actual draw ratio was determined from the change in the length between the markers before and after drawing. The extrusion temperature was 125 ° C.

For the stretching of the two-step surface, the tape-shaped sample coextruded in the first step was stretch-stretched at 125 ° C. The stretching was performed using a tensile tester equipped with a high temperature tank. The stretch ratio was determined from the change in length between the markers before and after stretching. The total draw ratio by the two-stage drawing was obtained by multiplying the draw ratio by the first-stage coextrusion drawing and the draw ratio by the second-stage tensile drawing. This time, using the above method, the total draw ratio is about 200.
Alternatively, fibers of 150 were produced.

[Evaluation of Physical Properties] Here, the tensile elastic modulus and the tensile breaking strength of the drawn fiber were measured.

1. Tensile Elastic Modulus The tensile elastic modulus of the obtained fiber was measured at room temperature using a tensile tester. The initial strain rate in the measurement was 1 × 10 ⁻³ . The tensile modulus was estimated from the gradient of the initial linear region in the obtained stress-strain curve.

2. Fiber breaking strength The fiber breaking strength of the obtained fiber was measured using a tensile tester.
The tensile breaking strength was evaluated. The measurement was performed at room temperature. The initial strain rate in the measurement was 1 × 10 ^-2 . The tensile breaking strength was estimated from the stress at the obtained fiber break.

Each example and comparative example will be described below.

The polyethylene polymer used in Example 1 is an ethylene homopolymer (A1). First, (A
The manufacturing method of 1) will be described.

[Preparation of metallocene-supported catalyst] A 300 ml Schlenk tube was charged with silica (F
952) 13 g was introduced and dried under reduced pressure at 180 ° C. for 5 hours. To this Schlenk tube, 85 ml of toluene was introduced, and then 40 ml of a toluene solution of methylaluminoxane (aluminum concentration: 1.51 mol / liter) was dropped while stirring at room temperature. The obtained suspension was further stirred at 50 ° C. for 2 hours and then allowed to stand at room temperature for 1 hour to remove the supernatant. The obtained solid was washed twice with 20 ml of toluene, and toluene 4 was added again.
0 ml was introduced. 0.82 g (1.37 mmol) of diphenylmethylene (cyclopentadienyl) (2-dimethylaminofluorenyl) zirconium dichloride dissolved in 40 ml of toluene was added dropwise to the obtained suspension at room temperature with stirring. did. The resulting suspension was stirred at room temperature for a further 4 hours, then allowed to stand at room temperature for 16 hours and the supernatant was removed. The obtained solid was washed with 40 ml of toluene, and 40 ml of decane was introduced. 50 ml of a toluene solution of methylaluminoxane (aluminum concentration: 1.51 mol / liter) was added dropwise to the obtained suspension at room temperature with stirring, and the mixture was further stirred at room temperature for 20 minutes. The liquid component of the obtained suspension was evaporated under reduced pressure at a temperature of 100 to 110 ° C. to obtain a metallocene-supported catalyst as a red solid. As a result of elemental analysis, the obtained metallocene-supported catalyst had 45 μmol of metallocene compound and 6.7 mmol of aluminum supported on 1 g of the metallocene-supported catalyst.

[Ethylene polymerization] In a 2-liter autoclave, 1200 ml of n-hexane and n-hexane were added.
After introducing 0.19 ml of a hexane solution of butyl lithium (1.6 mol / liter), the internal temperature of the autoclave was raised to 75 ° C. with stirring, and the total ethylene pressure was 35 kg / cm ² · G. I introduced it until. Subsequently, 100 mg of the above metallocene-supported catalyst was pressed into this autoclave together with nitrogen of 40 kg / cm ² · G to initiate polymerization. During the polymerization, the total pressure is 40 kg / cm ²
-Ethylene was continuously introduced so as to be kept at G. The polymerization temperature was 80 ° C. 90 minutes after the start of the polymerization, the internal pressure of the autoclave was released to 0 kg / cm ² · G to complete the polymerization. The content of the autoclave was filtered, and the obtained ethylene homopolymer was dried under reduced pressure at room temperature for 24 hours. As a result, 240 g of ethylene homopolymer (A
1) was obtained.

As Example 1, Table 1 shows the viscosity average molecular weight (M _v ), weight average molecular weight (M _w ) / number average molecular weight (M _n ) of (A1). Table 2 shows the tensile elastic modulus and the tensile breaking strength of the drawn fibers having a total draw ratio of about 200 produced from (A1) by the above method.

Comparative Example 1 is the same as the ethylene homopolymer (A1) used in Example 1 except that the ethylene homopolymer (B1) obtained with a vanadium catalyst has the same M _v and M _w as the above method. It is a produced fiber. Table 1 shows (B
1) shows M _v and M _w / M _n , and Table 2 shows (B1)
The tensile elastic modulus and the tensile breaking strength of the drawn fiber having a total draw ratio of about 200 produced by the above method are shown below.

The polyethylene polymer used in Example 2 is an ethylene homopolymer. Polymerization was carried out in the same manner as in Example 1 except that the polymerization temperature was 60 ° C. As a result, 280 g of ethylene homopolymer (A2) was obtained. Table 1 shows M _v and M _w / M _n of (A2), and Table 2 shows the tensile elastic modulus and the tensile modulus of the drawn fiber having a total draw ratio of about 200 produced from (A2) by the above method. The breaking strength is shown.

Comparative Example 2 was prepared from the ethylene homopolymer (B2) obtained in the vanadium catalyst having the same M _v and M _w as the ethylene homopolymer (B2) used in Example 2 by the above method. It is a produced fiber. Table 1 shows (B
2) M _v and M _w / M _n are shown, and in Table 2, (B2)
The tensile elastic modulus and the tensile breaking strength of the drawn fiber having a total draw ratio of about 200 produced by the above method are shown below.

The polyethylene polymer used in Example 3 is an ethylene homopolymer. In the polymerization of ethylene, a hexane solution of n-butyllithium (1.6 mol /
Liter) hexane solution of alkylaluminum instead of 0.19 ml (0.71 mol / liter)
Polymerization was carried out in the same manner as in Example 1 except that 0.7 ml was used. As a result, 230 g of ethylene homopolymer (A3) was obtained.

Table 1 shows M _v and M _w / M _{n of} (A3).
Table 2 shows the tensile elastic modulus and the tensile breaking strength of the drawn fiber having a total draw ratio of about 150 produced from (A3) by the above method.

Comparative Example 3 was prepared from the ethylene homopolymer (B3) obtained by the vanadium-based catalyst having the same M _v and M _w as the ethylene homopolymer (A3) used in Example 3 by the above-mentioned method. It is a produced fiber. Table 1 shows (B
3) M _v and M _w / M _n are shown in Table 2 and (B3)
The tensile elastic modulus and tensile breaking strength of the drawn fiber having a total draw ratio of about 150 produced by the above method are shown below.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

As described above, the ultra-high elastic modulus high strength fiber made of the polyethylene polymer of the present invention has a tensile elastic modulus and a tensile rupture as compared with the similar fiber obtained from the conventional polyethylene polymer. It has improved strength.

Claims (1)

[Claims] And a 1. A viscosity-average molecular weight (M _v) is 30 × 10 ⁴ or more, weight average molecular weight (M _w) and number average molecular weight ratio _{(M n) (M w /} M n) is 3 or less An ultrahigh elastic modulus and high strength fiber obtained from a high molecular weight ethylene homopolymer or a copolymer of ethylene and 0.5 mol% or less of α-olefin.