JP2557459B2 - Tow rope - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a tow rope, and more particularly to a tow rope that is used for paragliders, water skis and the like and has excellent lightness, safety to human bodies and weather resistance.

TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS THEREOF A metal rope (wire) has been used as a tow rope used in paragliders, water skis and the like. However, the metal rope has a problem that it is so heavy that it sinks into water and is difficult to handle, and the metal rope has a problem that it injures a human body.

Furthermore, the elongation against tensile stress is small, and the impact during towing directly affects the towing body, which in turn damages the towing body due to a sudden impact, and since the impact absorption capacity is low, damage and breakage of the rope itself can occur. There is a problem of reaching.

An object of the present invention is to solve the problems associated with the prior art as described above, and it is lightweight and easy to handle because it floats on water and is excellent in safety and weather resistance for the human body. Intended to provide rope.

SUMMARY OF THE INVENTION The tow rope according to the present invention is a tow rope having a two-layer structure in which the outer periphery of a core member is covered with a sheath member, and the core member has an intrinsic viscosity [η] of at least 5 dl / g. The sheath member comprises a molecularly oriented molded body of an ultrahigh molecular weight ethylene / α-olefin copolymer having an average content of 0.1 to 20 carbon atoms per 1000 carbon atoms of α-olefin having 3 or more carbon atoms. However, the feature is that it consists of a knit.

The tow rope according to the present invention has a double structure consisting of a core member and a sheath member, and the core member is made of an ultra-high molecular weight polyolefin molecularly oriented molded article excellent in strength and elasticity. As it is composed of knitted fabric, it floats on water and is easy to handle, and at the same time, it has excellent human safety and weather resistance.

In addition, especially when the core member is a molecular orientation molded product of an ultrahigh molecular weight ethylene / α-olefin copolymer, the elongation under load is large, and the amount of energy until rupture is large, which is unexpected. The impact exerted on the towed body of the towed object due to the impact force is small, and it is excellent in avoiding the fracture.

Specific Description of the Invention Hereinafter, the tow rope according to the present invention will be specifically described.

As shown in the perspective view of FIG. 1 , the tow rope 1 according to the present invention has a double structure in which a core member 2 and an outer periphery thereof are covered with a sheath member 3.

The core member 2 is configured to include a molecular orientation molded body of ultra-high molecular weight polyolefin.

As such a polyolefin molecular orientation molded article,
Specifically, ultrahigh molecular weight polyethylene, ultrahigh molecular weight polypropylene, ultrahigh molecular weight ethylene / α-olefin copolymer and the like are used. Of these, ultra high molecular weight polyethylene mainly composed of ethylene or ultra high molecular weight ethylene / α
-Ultrahigh-molecular-weight polyethylene obtained by stretching the olefin copolymer at a high draw ratio of 10 times or more, the molecular orientation molded product is lightweight, and also has high elasticity and high tensile strength, so that it is preferable. Used.

The molecular orientation molded article of ultra-high molecular weight polyolefin and the molecular orientation molded article of ultra-high molecular weight ethylene / α-olefin high polymer, that is, the molecular orientation molded article of ultra-high molecular weight ethylene / α-olefin copolymer, which is particularly used in the present invention, Will be described.

The molecular orientation molded article used in the present invention is an ultra-high molecular weight polyolefin molecular orientation molded article or an ultra-high molecular weight ethylene / α-olefin copolymer molecular orientation molded article.

As the ultrahigh molecular weight polyolefin constituting the molecular orientation molded article of the present invention, specifically, ultrahigh molecular weight polyethylene, ultrahigh molecular weight polypropylene, ultrahigh molecular weight poly-1-
Examples thereof include butene and an ultrahigh molecular weight copolymer of two or more α-olefins. This ultra-high molecular weight polyolefin molecularly oriented molded article is lightweight, has high strength, and is excellent in water resistance and salt water resistance.

Further, as the ultrahigh molecular weight ethylene / α-olefin copolymer constituting the molecular orientation molded article of the present invention, an ultrahigh molecular weight ethylene / propylene copolymer, an ultrahigh molecular weight ethylene / 1-butene copolymer, an ultrahigh molecular weight Molecular weight ethylene-4-methyl-1-pentene copolymer, ultra high molecular weight ethylene-1-
Hexene copolymers, ultra-high molecular weight ethylene / 1-octene copolymers, ultra-high molecular weight ethylene / 1-decene copolymers, etc., having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms.
The ultra-high molecular weight ethylene / α-olefin copolymer with α-olefin can be exemplified. In this ultra-high molecular weight ethylene / α-olefin copolymer, the α-olefin having 3 or more carbon atoms is 0.1 per 1000 carbon atoms of the polymer.
.About.20, preferably 0.5 to 10, and more preferably 1 to 7.

The molecular orientation molded product obtained from such an ultrahigh molecular weight ethylene / α-olefin copolymer is particularly excellent in impact resistance and creep resistance as compared with the molecular orientation molded product obtained from an ultrahigh molecular weight polyethylene. . This ultrahigh molecular weight ethylene / α-olefin copolymer is lightweight and has high strength, and is excellent in abrasion resistance, impact resistance, creep resistance, weather resistance, water resistance, and salt water resistance.

The ultrahigh molecular weight polyolefin or ethylene / α-olefin copolymer constituting the molecular orientation molded article of the present invention is
Its intrinsic viscosity [η] is 5 dl / g or more, preferably 7 to 30 dl / g
The molecular orientation molded product obtained from this copolymer has excellent mechanical properties or heat resistance. That is, since the molecular terminals do not contribute to the fiber strength and the number of molecular terminals is the reciprocal of the molecular weight (viscosity), the intrinsic viscosity [η]
The larger one gives higher strength.

The density of the molecularly oriented molded article of the present invention is 0.940 to 0.990 g / cm.
^{3 It is} preferably 0.960 to 0.985 g / cm ³ . Where the density is
According to a standard method (ASTM D 1505), measurement was performed by a density gradient tube method. The density gradient tube at this time was prepared by using carbon tetrachloride and toluene, and the measurement was performed at room temperature (23 ° C).

The dielectric constant (1 KHz, 23 ° C.) of the molecular orientation molded product of the present invention is:
1.4-3.0, preferably 1.8-2.4, the positive tangent (1KHz,
80 ° C.) is 0.05 to 0.008%, preferably 0.040 to 0.010%. Here, the dielectric constant and the positive tangent were measured by ASTM D150 using a film-shaped sample in which fibers and a tape-shaped molecular alignment material were densely aligned in one direction.

The stretching ratio of the molecularly oriented molded article of the present invention is 5 to 80 times, preferably 10 to 50 times.

The degree of molecular orientation in the molecular orientation molded article of the present invention is
It can be known by an X-ray diffraction method, a birefringence method, a fluorescence polarization method and the like. When the ultrahigh molecular weight polymer of the present invention is a drawn filament, for example, Yukichi Kure and Teruichiro Kubo: Industrial Chemistry Magazine No. 39
Vol., P. 992 (1939), the degree of orientation according to the half-value width, (In the formula, H ° is the half-value width (°) of the intensity distribution curve along the Debye ring of the strongest paratropic plane on the equator.) The degree of orientation (F) defined by is 0.90 or more, especially 0.95 or more. It is desirable from the viewpoint of mechanical properties that the molecules are oriented so that

Furthermore, the molecular orientation molded article of the present invention is also excellent in mechanical properties, for example, 20 GPa in the form of a drawn filament.
Above, especially elastic modulus of 30 GPa or more, and 1.2 GPa or more, especially 1.5
It has a tensile strength of GPa or more.

The impulse voltage breakdown value of the molecular orientation molded product of the present invention is:
It is 110 to 250 KV / mm, preferably 150 to 220 KV / mm. The impulse voltage breakdown value uses the same sample as for the dielectric constant,
The pressure was increased with a brass (25 mmφ) JIS type electrode while applying a negative impulse in 2 KV / 3 steps on a copper plate, and the measurement was performed.

The molecular orientation molded product of the present invention is an ultra-high molecular weight ethylene
In the case of a molecularly oriented molded article of an olefin copolymer,
This molecularly oriented molded article is characterized by remarkably excellent impact resistance, breaking energy and creep resistance. The characteristics of these molecularly oriented molded products of these ultrahigh molecular weight ethylene / α-olefin copolymers are represented by the following physical properties.

The breaking energy of the molecularly oriented molded product of the ultrahigh molecular weight ethylene / α-olefin copolymer used in the present invention is 8 kg
/ g or more, preferably 10 kg · m / g or more.

Further, the molecularly oriented molded article of the ultrahigh molecular weight ethylene / α-olefin copolymer of the present invention has excellent creep resistance. In particular, it has a remarkably excellent creep resistance at high temperatures, which is equivalent to the condition for promoting creep at room temperature.
As the% breaking load, the atmospheric temperature was 70 ° C., the creep (90%) after 90 seconds was 7% or less, especially 5% or less, and the creep rate (ε,
sec ^-1 ) is 4 × 10 ^-4 sec ^-1 or less, especially 5 × 10 ^-5 sec ^-1 or less.

Among the molecular oriented materials of the present invention, ultra high molecular weight ethylene
The molecular orientation product of the α-olefin copolymer has the above-mentioned ordinary temperature properties, but in addition to these ordinary temperature properties,
It is preferable to combine the following thermal properties because the above-mentioned physical properties at room temperature are further improved and the heat resistance is excellent.

The molecularly oriented molded body of the ultra-high molecular weight ethylene / α-olefin copolymer used in the present invention has at least one crystal melting peak at a temperature at least 20 ° C. higher than the crystal melting temperature (Tm) of the copolymer. Heat of fusion based on (Tp)
It is at least 15%, preferably at least 20%, particularly at least 30%.

Original crystalline melting temperature of ultra high molecular weight ethylene copolymer (T
m) is, once this molded body is completely melted and then cooled,
After relaxing the molecular orientation in the molded body, the method of raising the temperature again, the so-called second scanning in the so-called differential scanning calorimeter
You can ask in a run.

To further explain, in the molecular oriented molded product of the present invention, the crystal melting peak does not exist at all in the crystal melting temperature range of the above-mentioned copolymer, or if it exists, it exists only as a very small tailing. . The crystal melting peak (Tp) is generally in the temperature range Tm + 20 ° C to Tm + 50 ° C, especially Tm
It is usually represented in the region of + 20 ° C to Tm + 100 ° C, and this peak (Tp) is often represented as a plurality of peaks within the above temperature range. That is, this crystal melting peak (Tp) is the high temperature side melting peak (Tp ₁ ) in the temperature range Tm + 35 ° C to Tm + 100 ° C and the temperature range Tm + 20 ° C to Tm.
Often appearing to separate into two low temperature side melting peak (Tp ₂₎ at + 35 ° C., depending on the production conditions of molecular orientation moldings, also Tp ₁ and Tp ₂ consists further plurality of peaks is there.

These high crystal melting peaks (Tp ₁ and Tp ₂ ) significantly improve the heat resistance of the molecularly oriented compact of ultra-high molecular weight ethylene / α-olefin copolymer, and also the strength retention rate after high temperature heat history. Alternatively, it seems to contribute to the elastic modulus retention rate.

Further, the total sum of the heat of fusion based on the high temperature side melting peak (Tp ₁ ) in the temperature range Tm + 35 ° C. to Tm + 100 ° C. is preferably 1.5% or more, particularly 3.0% or more, based on the total heat of fusion.

As long as the total heat of fusion based on the high-temperature side melting peak (Tp ₁ ) satisfies the above value, if the high-temperature side melting peak (Tp ₁ ) does not appear as a major peak, that is, the small peak Even if it has an aggregate or a broad peak, the heat resistance may be slightly lost, but the creep resistance is excellent.

The melting point and the heat of crystal fusion in the present invention were measured by the following methods.

The melting point was measured by a differential scanning calorimeter as follows. As the differential scanning calorimeter, DSC II type (manufactured by Perkin Elmer) was used. The sample was constrained in the orientation direction by winding about 3 mg around an aluminum plate having a thickness of 4 mm × 4 mm and a thickness of 0.2 mm. Then, the sample wound around the aluminum plate was enclosed in an aluminum pan to obtain a measurement sample. In addition, the same aluminum plate as that used for the sample was normally enclosed in an empty aluminum pan to be put in the reference holder to balance the heat. First, the sample is about 1 at 30 ℃
The temperature was maintained for 10 minutes, and then the temperature was raised to 250 ° C. at a temperature rising rate of 10 ° C./minute to complete the first melting point measurement at the time of heating. Continue
The sample was held at 250 ° C. for 10 minutes, then cooled at a cooling rate of 20 ° C./min, and further held at 30 ° C. for 10 minutes. Next, the second heating was carried out at a heating rate of 10 ° C./min to 250 ° C., and the melting point measurement at the second heating (second run) was completed. At this time, the maximum value of the melting peak was taken as the melting point. When it appears as a shoulder, a tangent line was drawn between the inflection point on the low temperature side and the inflection point on the high temperature side of the shoulder, and the intersection was taken as the melting point.

Also, from the melting point (Tm) of the original crystal melting point (Tm) of the ultrahigh molecular weight ethylene copolymer, which is obtained by connecting the points of 60 ° C and 240 ° C of the endothermic curve to the straight line (baseline) and the main melting peak at the time of the second heating A perpendicular line is drawn at a point higher by ℃, the low temperature side surrounded by these is based on the original crystal melting (Tm) of the ultra high molecular weight ethylene copolymer, and the high temperature side is the function of the molded product of the present invention. It was based on the crystal melting (Tp) that developed, and the heat of fusion of each crystal was calculated from these areas. Also, the heat of fusion based on the melting of Tp ₁ and Tp ₂ was measured according to the method described above, and the perpendicular line from Tm + 20 ° C and Tm + 35
The portion surrounded by the vertical line from ℃ was the one with the heat of fusion based on the melting of Tp ₂ , and the high temperature side was the one with the heat of fusion based on the melting of Tp ₁ .

The drawn filament of the ultra-high molecular weight ethylene / α-olefin copolymer of the present invention has a strength retention of 95% or more and a modulus retention of 90 after being subjected to a heat history of 5 minutes at 170 ° C.
% Or more, particularly 95% or more, and has excellent heat resistance that is not found in conventional drawn filaments of polyethylene.

Method for producing molecularly oriented molded body of ultra-high molecular weight polyolefin As a method for obtaining the above-mentioned ultra-high molecular weight polyolefin stretched product having high elasticity and high tensile strength, for example, JP-A-
56-15408, JP 58-5228, JP 59
-130313, JP-A-59-187614, etc., a ultra-high molecular weight polyolefin is made into a dilute solution, or a low-molecular weight compound such as paraffin wax is added to the ultra-high molecular weight polyolefin. Then, a method of improving the stretchability of the ultrahigh molecular weight polyolefin and stretching it at a high ratio can be exemplified.

Method for Producing Molecularly Oriented Molded Body of Ultra High Molecular Weight Ethylene / α-Olefin Copolymer The present invention will be described below in the order of raw materials, production method and purpose for easy understanding.

Raw Materials The ultrahigh molecular weight ethylene / α-olefin copolymer used in the present invention is obtained by slurry polymerizing ethylene and an α-olefin having 3 or more carbon atoms using a Ziegler-based catalyst, for example, in an organic solvent. .

Examples of the α-olefin having 3 or more carbon atoms include propylene, butene-1, pentene-1,4-methylpentene-
1, hexene-1, heptene-1, octene-1 and the like are used, and among them, butene-1, 4-methylpentene-1, hexene-1, octene-1 and the like are particularly preferable. Such α-olefins are copolymerized with ethylene such that they are present in the above amounts per 1000 carbons of the resulting copolymer. Further, the ultrahigh molecular weight ethylene / α-olefin copolymer used as a base in the production of the molecular oriented material in the present invention should have a molecular weight corresponding to the above-mentioned intrinsic viscosity [η].

The quantification of the α-olefin component in the ultrahigh molecular weight ethylene / α-olefin copolymer used in the present invention is performed by an infrared spectrophotometer (manufactured by JASCO Corporation). Specifically, the absorbance at 1378 cm ^-1 , which represents the bending vibration of the methyl group of the α-olefin incorporated in the ethylene chain, was measured by an infrared spectrophotometer, and this value was measured in advance at ¹³ C.
The amount of α-olefin in the ultra-high molecular weight ethylene / α-olefin copolymer was calculated by converting the number of methyl branches per 1000 carbon atoms using a calibration curve prepared using a model compound with a nuclear magnetic resonance apparatus. Is quantified.

Production Method In the present invention, when producing a molecular orientation product from the above ultrahigh molecular weight ethylene / α-olefin copolymer, a diluent is added to the copolymer. Such diluents include:
Various waxes having compatibility with the solvent for the ultra high molecular weight ethylene copolymer or the ultra high molecular weight ethylene copolymer are used.

As such a solvent, a melting point equal to or higher than the melting point of the copolymer, more preferably 20 ° C. higher than the melting point of the copolymer.
A solvent having a high melting point is used.

Specific examples of such a solvent include n-nonane,
n-decane, n-undecane, n-dodecane, n-tetradecane, n-octadecane or liquid paraffin,
Aliphatic hydrocarbon solvents such as kerosene, xylene, naphthalene, tetralin, butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, benchylbenzene, dodecylbenzene, bicyclohexyl, decalin,
Aromatic hydrocarbon solvents such as methylnaphthalene, ethylnaphthalene or hydrogenated derivatives thereof, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1,2,3-trichloropropane, dichlorobenzene,
Examples thereof include halogenated hydrocarbon solvents such as 1,2,4-trichlorobenzene and bromobenzene, and mineral oils such as paraffin type process oil, naphthene type process oil, and aromatic type process oil.

As the wax as the diluent, specifically, an aliphatic hydrocarbon compound or its derivative is used.

As such an aliphatic hydrocarbon compound, a compound mainly composed of a saturated aliphatic hydrocarbon compound and usually having a molecular weight of 2000 or less, preferably 1000 or less, more preferably 800 or less, called a paraffin wax is used.

Specific examples of such an aliphatic hydrocarbon compound include n-alkanes having 22 or more carbon atoms such as docosane, tricosane, tetracosane, and triacontane, or a mixture thereof with a lower n-alkane containing them as a main component, petroleum oil. So-called paraffin wax isolated and purified from ethylene, a low-molecular weight polyethylene wax, a high-pressure polyethylene wax, a styrene copolymer wax or a medium-low-pressure polyethylene wax which is a low molecular weight polymer obtained by copolymerizing ethylene or ethylene with another α-olefin. -Waxes obtained by reducing the molecular weight of polyethylene such as low-pressure polyethylene and high-pressure polyethylene by thermal degradation, oxides of these waxes, oxidized waxes such as maleic acid-modified waxes, and maleic acid-modified waxes are used.

The aliphatic hydrocarbon compound derivative is, for example, one or more, preferably 1 to 2 at the terminal or inside of the aliphatic hydrocarbon group (alkyl group, alkenyl group).
A compound having a functional group such as a carboxyl group, a hydroxyl group, a carbamoyl group, an ester group, a meltcapto group, and a carbonyl group, and particularly preferably one having 8 or more carbon atoms, preferably 12 to 50 carbon atoms or 130 to 2000 molecular weight. Preferably, 200 to 800 fatty acids, aliphatic alcohols, fatty acid amides, fatty acid esters, aliphatic mercaptans, aliphatic aldehydes and aliphatic ketones are used.

As such an aliphatic hydrocarbon compound derivative, specifically, fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid,
Aliphatic alcohols such as laurin alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol, fatty acid amides such as caprinamide, laurinamide, palmitinamide, and stearylamide, and fatty acid esters such as stearyl acetate are used.

The ultrahigh molecular weight ethylene / α-olefin copolymer and the diluent are different depending on their types.
It is used in a weight ratio of 3:97 to 80:20, in particular 15:85 to 60:40. When the amount of the diluent is lower than the above range, the melt viscosity becomes too high, which makes melt-kneading and melt-molding difficult, and the resulting molded article is significantly roughened, and stretch breakage is likely to occur. On the other hand, when the amount of the diluent is more than the above range, the melt-kneading becomes difficult and the stretchability of the obtained molded product becomes poor.

Melt kneading is generally carried out at temperatures of 150 to 300 ° C, especially 170 to 270 ° C. At a temperature lower than the above range, the melt viscosity is too high and melt molding becomes difficult. When the temperature is higher than the above range, ultra-high molecular weight ethylene
The molecular weight of the α-olefin copolymer decreases, and it becomes difficult to obtain a molded product having excellent high elastic modulus and high strength. The blending may be carried out by a dry blend using a Henschel mixer, a V-type blender or the like, or may be carried out using a single screw extruder or a multi-screw extruder.

Melt molding of a dope (stock solution for spinning) composed of an ultrahigh molecular weight ethylene / α-olefin copolymer and a diluent is generally carried out by melt extrusion molding. Specifically, a filament for drawing is obtained by melt-extruding the dope through a spinneret. At this time, a draft, that is, stretching in a molten state, can be added to the melt extruded from the spinneret. The ratio of the extrusion speed V ₀ of the molten resin in the die orifice and the winding speed V of the unstretched material that has been cooled and solidified can be defined as the draft ratio by the following formula.

Draft ratio = V / V ₀ (2) Such a draft ratio varies depending on the temperature of the mixture, the molecular weight of the ultra high molecular weight ethylene copolymer, and the like, but is usually 3 or more, preferably 6 or more. .

Next, the ultra high molecular weight ethylene
The unstretched molded product of the α-olefin copolymer is stretched. The stretching is performed so that the unstretched molded product obtained from the ultra-high molecular weight ethylene / α-olefin copolymer is effectively imparted with at least uniaxial molecular orientation.

The stretching of an unstretched molded article obtained from an ultrahigh molecular weight ethylene / α-olefin copolymer is generally 40 to 160 ° C, particularly 8
It is carried out at a temperature of 0 to 145 ° C. As a heat medium for heating and holding the unstretched molded article at the above temperature, air, steam,
Any liquid medium can be used. However, as a heat medium, a solvent capable of eluting and removing the above-mentioned diluent, and a liquid medium whose boiling point is higher than the melting point of the molded body composition, specifically, decalin, decane,
When the stretching operation is performed using kerosene or the like, it is possible to remove the above-mentioned diluent, and it is possible to achieve a high stretching ratio without causing uneven stretching during stretching.

The means for removing the diluent from the ultrahigh molecular weight ethylene / α-olefin copolymer is not limited to the above method, and a method of stretching the unstretched material after treating it with a solvent such as hexane, heptane, hot ethanol, chloroform, benzene, or the like, A stretched product having a high elastic modulus and high strength can also be obtained by removing the diluent in the molded product by a method of treating the stretched product with a solvent such as hexane, heptane, hot ethanol, chloroform or benzene.

The stretching operation can be performed in one stage or in multiple stages of two or more stages. The draw ratio generally depends on the desired molecular orientation and the effect of improving the melting temperature accompanied therewith, but generally 5
8080 times, preferably 10 to 50 times.

Generally, it is preferable to carry out the stretching operation by multi-stage stretching of two or more stages, and in the first stage, the stretching operation is performed while extracting the diluent in the extrusion-molded product at a relatively low temperature of 80 to 120 ° C, and the second stage. After that, it is preferable to perform the stretching operation of the molded body at a temperature of 120 to 160 ° C. and a temperature higher than the first stage stretching temperature.

In the case of the uniaxial stretching operation, tensile stretching may be performed between rollers having different peripheral speeds.

The molecular orientation molded body thus obtained can be heat-treated under restraint conditions, if desired. This heat treatment is generally 140-180 ℃, preferably at a temperature of 150-175 ℃,
It can be carried out for 1 to 20 minutes, preferably 3 to 10 minutes.
By heat treatment, crystallization of the oriented crystal part further progresses, shift of the crystal melting temperature to a high temperature side, improvement of strength and elastic modulus,
Further, the creep resistance at high temperature is improved.

The core member that constitutes the tow rope of the present invention is composed of an ultra-high molecular weight polyolefin molecular orientation molded body, and this core member is composed of a bundle obtained by aligning and bundling ultra-high molecular weight polyolefin filaments. Alternatively, the stretched filaments may be formed by twisting, braiding or braiding of three-strand, four-strand, six-strand, eight-strand, para-strand and the like. When the core member is composed of a knitted product of drawn filaments, the number of drawn filaments, the diameter, etc. can be selected according to the application and purpose of the rope.

The diameter of such a core member is preferably about 2 to 15 mm.

The breaking energy of the core member of the tow rope of the present invention braided into a rope is 3 kgm / g or more, preferably 4 kg.
・ M / g or more. Further, the decrease (more decrease) in the strength utilization factor when braided is also a characteristic of the molecular orientation molded product used in the present invention.

On the other hand, the sheath member 3 is composed of a knit. As the yarn or strand constituting the knit, conventionally known natural fibers or synthetic fibers can be used. Specifically, polyester fibers, acrylic fibers, cotton, polypropylene fibers, polyethylene fibers, polyamide fibers, rayon (viscose / rayon, cupra), hemp, vinylon fibers and the like can be preferably used.

The number of perforations or the circumference of the knitted material forming the sheath member 3 is
Although it can be appropriately selected depending on the use of the rope, specifically, the peripheral diameter, that is, the thickness of the sheath member 3 is preferably about 0.1 to 2 mm.

Next, a method of manufacturing the tow rope according to the present invention will be described.

First, a double-blade rope including a core member and a sheath member (knitted material) is prepared according to a conventional method. Production of such a double braid rope itself, for example, while aligning or braiding ultra-high molecular weight polyolefin filaments to form a core member, or pre-aligned or braided core member, a large number of yarns or strands on the outer periphery of the core member. It is possible to exemplify a method of spirally winding while crossing each other and braiding in a tubular shape.

EFFECTS OF THE INVENTION The tow rope according to the present invention has a double structure including a core member and a sheath member, and the core member has strength, elasticity,
Since it is composed of an ultra-high molecular weight polyolefin molecularly oriented molded product excellent in lightness and the sheath member is composed of a knitted product, it floats on water and is easy to handle, and at the same time, it is excellent in safety for human body and weather resistance.

In particular, the traction rope according to the present invention, in which the core member is composed of a molecular orientation molded product of an ultra-high molecular weight ethylene / α-olefin copolymer, has a large elongation under load in addition to the above effects, and Since the amount of energy until the breakage is large, the shock exerted on the towed body of the towed object due to the sudden impact force is small, and it is excellent in avoiding the breakage.

Example 1 <Polymerization of Ultra High Molecular Weight Ethylene / Butene-1 Copolymer> Using an Ziegler catalyst, n-decane 1 was used as a polymerization solvent to carry out slurry polymerization of the ultra high molecular weight ethylene / butene-1 copolymer. . A mixed monomer gas having a molar ratio of ethylene and butene-1 of 97.2: 2.35 was continuously supplied to the reactor so that the pressure was kept constant at 5 kg / cm ² . The polymerization was completed in 2 hours at a reaction temperature of 70 ° C.

The yield of the ultra-high molecular weight ethylene-butene-1 copolymer powder obtained was 160 g and the intrinsic viscosity [η] (decalin: 135 ° C) was
8.2 dl / g, butene-1 content by infrared spectrophotometer is 1000
The number was 1.5 per carbon atom.

<Preparation of Ultra-High Molecular Weight Ethylene / Butene-1 Copolymer Stretched Alignment> 20 parts by weight of ultra-high molecular weight ethylene / butene-1 copolymer powder obtained by the above polymerization and paraffin wax (melting point = 69 ° C., molecular weight = 490) 80 parts by weight of the mixture was melt-spun under the following conditions.

3,5-di- as a process stabilizer was added to 100 parts by weight of the mixture.
0.1 parts by weight of tert-butyl-4-hydroxytoluene was blended. Next, the mixture is fed into a screw type extruder (screw diameter = 25 mm, L / D = 25, manufactured by Thermoplastics Co., Ltd.)
Was melt-kneaded at a preset temperature of 190 ° C. Subsequently, the mixed melt was attached to the extruder and the orifice diameter was 2 m.
Melt spinning was performed using a spinning die of m. The extruded melt was taken at a draft ratio of 36 times with an air gap of 180 cm, cooled in air and solidified to obtain an unstretched fiber. Further, the unstretched fiber was stretched under the following conditions.

Two-stage stretching was performed using three godet rolls.
At this time, the heat medium in the first drawing tank is n-decane, and the temperature is
At 110 ° C., the heat medium of the second stretching tank was triethylene glycol, and the temperature was 145 ° C. The effective length of each tank is 50c
m. At the time of stretching, the rotational speed of the first godet roll was set to 0.5 m / min and the rotational speed of the third godet roll was changed to obtain an oriented fiber having a desired draw ratio. The rotation speed of the second godet roll was appropriately selected within a range in which stable stretching was possible. Almost all the paraffin wax mixed in the initial stage was extracted into n-decane during stretching. After that, the oriented fiber was washed with water and dried under reduced pressure at room temperature for one day and then used for measurement of various physical properties. The stretching ratio was calculated from the rotation speed ratio of the first godet roll and the third godet roll.

<Measurement of Tensile Properties> Modulus of elasticity and tensile strength were measured at room temperature (23 ° C) using a Shimadzu DCS-50M type tensile tester.

At this time, the sample length between the clamps is 100 mm and the pulling speed is 1
It was 00 mm / min (100% / min strain rate). The elastic modulus was calculated using the initial elastic modulus and the slope of the tangent line. The fiber cross-sectional area required for the calculation was calculated from the weight with a density of 0.960 g / cc.

<Tensile Elastic Modulus and Strength Retention after Thermal History> The thermal history test was performed by leaving the device in a gear oven (Perfect Oven: manufactured by Tabai Seisakusho).

The sample had a length of about 3 m, and was folded back on a stainless steel frame having a plurality of pulleys at both ends to fix both ends of the sample. At this time, fix both ends of the sample so that the sample does not sag.
The sample was not actively tensioned. The tensile properties after thermal history were measured based on the description of the measurement of the tensile properties described above.

<Measurement of creep resistance> The creep resistance was measured using a thermal stress strain measuring device TMA / SS10 (manufactured by Seiko Denshi Kogyo Co., Ltd.) with a sample length of 1 cm, an ambient temperature of 70 ° C., and a load of 30 at the breaking load at room temperature. It was carried out under accelerated conditions with a weight corresponding to%. The following two values were obtained to quantitatively evaluate the amount of creep. That is, the value of creep elongation (%) CR ₉₀ at 90 seconds after applying a load to the sample,
The average creep speed from this 90 seconds to 180 seconds (s
ec ⁻¹ ) ε.

Table 1 shows the tensile properties of the multifilament obtained by bundling a plurality of the drawn oriented fibers.

Original crystalline melting peak of ultra-high molecular weight ethylene / butene-1 copolymer stretched filament (Sample-1) is 126.7
The ratio of Tp to the total crystal melting peak area at 3 ° C was 33.8%. Creep resistance is CR ₉₀ = 3.1%, ε = 3.03 x 1
It was 0 ^-5 sec ^-1 . Further, the elastic modulus retention rate after heat history at 170 ° C. for 5 minutes was 102.2% and the strength retention rate was 102.5%, and no deterioration in performance due to thermal history was observed.

The work required to break the drawn filament is 10.3
kg ・ m / g, density 0.973 g / cm ² , dielectric constant 2.2.
The dielectric loss tangent was 0.024%, and the impulse voltage breakdown value was 180 KV / mm.

Using the above-mentioned drawn filament, a tow rope of the present invention comprising the following core member and sheath member was produced.

Core member: An ultra high molecular weight ethylene / butene-1 copolymer filament (Sample-1) braided under the conditions of 12,000 denier and 8 shots.

Sheath member: Polyester spun yarn 1,000 denier braided under the conditions of 16 stitches.

 Table 2 shows the form and physical properties of the rope.

Example 2 <Polymerization of Ultra High Molecular Weight Ethylene / Octene-1 Copolymer> Slurry polymerization of ethylene was carried out using a Ziegler type catalyst and n-decane 1 as a polymerization solvent. At this time, 125 ml of octene-1 as a comonomer and 40 N ml of hydrogen for adjusting the molecular weight were added all at once before the initiation of the polymerization to initiate the polymerization. Ethylene gas was continuously supplied so that the pressure in the reactor was kept constant at 5 kg / cm ² , and the polymerization was completed at 70 ° C. for 2 hours. Obtained ultra high molecular weight ethylene octene-1
The yield of copolymer powder was 178 g, its intrinsic viscosity [η] (decalin, 135 ° C) was 10.66 dl / g, and the octene-1 comonomer content by infrared spectrophotometer was 0.5 per 1000 carbon atoms. It was

<Preparation of Stretched Oriented Material of Ultra High Molecular Weight Ethylene / Octene-1 Copolymer and Its Physical Properties> Stretched and oriented fibers were prepared by the method described in Example 1. Table 3 shows the tensile properties of the multifilament obtained by bundling a plurality of the drawn oriented fibers.

The original crystal melting peak of ultra-high molecular weight ethylene / octene-1 copolymer stretched filament (Sample-2) is 132.1.
The ratios of Tp and Tp ₁ to the total crystal melting peak area at ℃ were 97.7% and 5.0%, respectively. The creep resistance of Sample-2 was CR ₉₀ = 2.0% and ε = 9.50 × 10 ⁻⁶ sec ⁻¹ . The elastic modulus retention rate after heat history at 170 ° C. for 5 minutes was 108.2%, and the strength retention rate was 102.1%. Furthermore, the work required for fracture of Sample-2 is 10.1 kgm / g, the density is 0.971 g / cm ² , the density is 0.971 g / cm ² , the dielectric constant is 2.2, and the dielectric loss tangent is It was 0.031%, and the impulse voltage breakdown value was 185 KV / mm.

Using the ultrahigh molecular weight ethylene-octene-1 copolymer stretched filament (Sample-2), the tow rope of the present invention was obtained by the method described in Example 1. Table 4 shows the shape and physical properties of the rope.

Comparative Example 1 Ultrahigh molecular weight polyethylene (homopolymer) powder (intrinsic viscosity [η] = 7.42 dl / g, decalin, 135 ° C.): 20 parts by weight and paraffin wax (melting point = 69 ° C., molecular weight = 490):
A mixture with 80 parts by weight was melt-spun and drawn by the method of Example 1 to obtain drawn oriented fibers. Table 5 shows the tensile properties of the multifilament obtained by bundling a plurality of the drawn oriented fibers.

Ultra high molecular weight polyethylene drawn filament (Sample-
3) The original crystal melting peak was 135.1 ° C, and the ratio of Tp to the total crystal melting peak area was 8.8%. Similarly, the ratio of the high temperature side peak Tp ₁ to the total crystal melting peak area was 1% or less. Creep resistance is CR ₉₀ = 11.9%, ε
= 1.07 × 10 ^-3 sec ^-1 . The elastic modulus retention rate after heat history at 170 ° C. for 5 minutes was 80.4%, and the strength retention rate was 78.2%. Furthermore, the work required to break Sample-3 is 10.2 kg.
-M / g, the density was 0.985 g / cm ² , the dielectric constant was 2.3, the dielectric loss tangent was 0.030%, and the impulse voltage breakdown value was 182 KV / mm.

Ultra high molecular weight polyethylene drawn filament (Sample-
3) was used to obtain the tow rope of the present invention by the method described in Example 1. Table 6 shows the shape and physical properties of the rope.
Shown in

Comparative Example 2 Instead of the core material described in Example 1, Kevlar 29
A traction rope was prepared using 8400 denier aligned filaments (Aramid fiber manufactured by DuPont). Table 7 shows the morphology and physical properties of the rope.

[Brief description of drawings]

 FIG. 1 is a perspective view of a tow rope according to the present invention. 1 ... Towing rope 2 ... Core member 3 ... Sheath member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-53-58071 (JP, A) Actually open 62-129098 (JP, U) Actually open 62-126398 (JP, U)

Claims (4)

(57) [Claims] 1. A towing rope having a two-layer structure in which the outer periphery of a core member is covered with a sheath member, wherein the core member has an intrinsic viscosity [η] of at least 5 dl / g and a carbon number of 3 The content of the above α-olefin is composed of a molecular oriented molded product of an ultrahigh molecular weight ethylene / α-olefin copolymer having an average of 0.1 to 20 per 1000 carbon atoms, and the sheath member is composed of a knitted product. A rope for towing. 2. The molded article according to claim 1, wherein
The tow rope according to claim 1, comprising a bundle of drawn filaments. 3. The molecularly oriented molded body constituting the core member,
The tow rope according to claim 1, comprising a knitted product obtained by braiding drawn filaments. 4. The tow rope according to claim 1, wherein the sheath member is made of a knitted product obtained by braiding spun yarn.