JP3122479B2 - Racket gut - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket gut, and more particularly to a gut for a racket, which comprises a molecular orientation of an ultra-high molecular weight ethylene / α-olefin copolymer, has excellent creep resistance and weather resistance, and The present invention relates to a racket gut excellent in impact resistance and fatigue resistance.

[0002]

BACKGROUND OF THE INVENTION Gut is stretched on a tennis or badminton racket, and as such a racket gut, conventionally, sheep is used as a natural product and nylon is used as an artificial fiber. Have been. However, in recent years, the technical level of competition has advanced,
With the diversification of batting techniques, sheep and nylon guts cannot respond to these batting methods in terms of material properties, and a higher-quality gut material is desired. In fact,
Recently, aromatic polyamide (aramid) fibers such as Kevlar have been used in advanced competitions. The point on the material properties of the application of the fiber to the gut material is:
It has outstanding elastic modulus and strength as compared with conventional materials. However, this aromatic polyamide fiber has weather resistance,
There was a serious problem that the water resistance and fatigue resistance were inferior, the amount of energy required to reach breakage was relatively small, and it was easy to break.

In order to solve such problems, racket guts made of ultrahigh molecular weight polyethylene fibers have begun to be used. However, racket gut made of ultra-high molecular weight polyethylene fiber has a problem that when it is stretched on a racket with a large tension, it is inferior in creep resistance and is overstretched. Although it is suitable for professional players, it was not suitable for amateurs.

Accordingly, the disadvantages of these aromatic polyamide fibers and ultra-high molecular weight polyethylene fibers as racket guts are improved, greatly exceeding the performance of conventional racket guts, and suitable for all tennis and badminton enthusiasts. There is a need for a racket gut material.

[0005] It is already known that by molding ultrahigh molecular weight polyethylene into fibers, tapes and the like and stretching them, a molecularly oriented molded article having a high elastic modulus and a high tensile strength can be obtained. For example, JP-A-56-1540
No. 8 describes spinning a dilute solution of ultra-high molecular weight polyethylene and stretching the resulting filament. Also, JP-A-59-130313 discloses that
It is described that ultra-high molecular weight polyethylene and wax are melt-kneaded, the kneaded material is extruded, cooled and solidified and then stretched. Further, JP-A-59-187614 discloses that the above-mentioned melt-kneaded material is extruded and drafted. After cooling and solidifying,
Then, stretching is described.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems associated with the prior art as described above, and has excellent creep resistance and weather resistance, as well as impact resistance and fatigue resistance. It is also aimed at providing an excellent racket gut.

[0007]

SUMMARY OF THE INVENTION The racket gut according to the present invention has an intrinsic viscosity [η] of at least 5 dl / g and an average content of α-olefins having 3 or more carbon atoms per 1,000 carbon atoms of 0.1 to 0.1 dl / g. 20 ultra high molecular weight ethylene
It is characterized by comprising a molecular orientation body of an α-olefin copolymer.

The racket gut according to the present invention is composed of a molecular orientation of the ultrahigh molecular weight ethylene / α-olefin copolymer as described above, and has excellent creep resistance and weather resistance, and also has excellent resistance to creep. Also excellent in impact resistance and fatigue resistance.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the racket gut according to the present invention will be described in detail. First, the molecular orientation of the ultrahigh molecular weight ethylene / α-olefin copolymer constituting the racket gut according to the present invention. Will be described.

The molecularly oriented molded article used in the present invention is an ultrahigh molecular weight ethylene / α-olefin copolymer molecular oriented molded article. The molecular alignment body used in the present invention (hereinafter, referred to as
(Ultra high molecular weight ethylene / α-olefin copolymer) constituting ultra high molecular weight ethylene / propylene copolymer, ultra high molecular weight ethylene / 1-butene copolymer, ultra high molecular weight ethylene・ Ethylene such as 4-methyl-1-pentene copolymer, ultrahigh molecular weight ethylene / 1-hexene copolymer, ultrahigh molecular weight ethylene / 1-octene copolymer, ultrahigh molecular weight ethylene / 1-decene copolymer And α- having 3 to 20, preferably 4 to 10 carbon atoms.
An ultrahigh molecular weight ethylene / α-olefin copolymer with an olefin can be exemplified. In this ultrahigh molecular weight ethylene / α-olefin copolymer, α-olefins having 3 or more carbon atoms are contained in an amount of 0.1 to 1000 per 1000 carbon atoms of the polymer.
It is contained in an amount of 20, preferably 0.5 to 10, more preferably 1 to 7.

The molecularly oriented molded article obtained from the ultrahigh molecular weight ethylene / α-olefin copolymer has a particularly high impact resistance and creep resistance as compared with the molecularly oriented molded article obtained from ultrahigh molecular weight polyethylene. Are better. 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 ultra-high molecular weight ethylene / α-olefin copolymer constituting the molecular orientation molded product used in the present invention is:
Its intrinsic viscosity [η] is 5 dl / g or more, preferably 7 to
It is in the range of 30 dl / g, and the molecularly oriented molded article obtained from this copolymer has excellent mechanical properties or heat resistance. In other words, the molecular terminals do not contribute to the fiber strength, and the number of molecular terminals is the reciprocal of the molecular weight (viscosity). Thus, it can be seen that those having a higher intrinsic viscosity [η] give higher strength.

The density of the oriented molecular article used in the present invention is 0.940 to 0.990 g / cm ³ , preferably 0.960 to 0.985 g / cm ³ . Here, the density was measured by a density gradient tube method according to a conventional method (ASTM D1505). The density gradient tube at this time was prepared by using carbon tetrachloride and toluene, and the measurement was performed at normal temperature (23 ° C.).

The dielectric constant (1 KHz, 23 ° C.) of the molecular orientation molded product used in the present invention is 1.4 to 3.0, preferably 1.8 to 2.4, and the positive tangent (1 KHz, 80
° C) is 0.05 to 0.08%, preferably 0.040%.
To 0.010%. Here, the dielectric constant and the positive tangent were determined by precisely aligning the fiber and tape-shaped molecularly oriented molded products in one direction, and using a sample in the form of a film using ASTM D 1
Measured by 50.

[0015] The stretch ratio of the molecularly oriented molded product used in the present invention is 5 to 80 times, preferably 10 to 50 times. The degree of molecular orientation in the molecular orientation molded product used in the present invention can be known by an X-ray diffraction method, a birefringence method, a fluorescence polarization method, or the like. When the ultra-high molecular weight polymer used in the present invention is a drawn filament, for example, Yukichi Kure and Teruichiro Kubo: the degree of orientation according to the half-value width described in detail in Kogaku Kagaku Magazine Vol. 39, page 992 (1939), that is, formula (Where H ° is the half width (°) of the intensity distribution curve along the Debye ring of the strongest paratropic plane on the equator line). The orientation degree (F) is 0.90 or more, especially It is desirable from the viewpoint of mechanical properties that the molecular orientation is 0.95 or more.

Further, the molecular orientation molded product of the ultra-high molecular weight ethylene / α-olefin copolymer used in the present invention is:
It is also excellent in mechanical properties, for example, in the form of a drawn filament, it has an elastic modulus of 20 GPa or more, especially 30 GPa or more, and a tensile strength of 1.2 GPa or more, especially 1.5 GPa or more.

The impulse voltage breakdown value of the molecular orientation molded product used in the present invention is 110 to 250 kV / mm, preferably 150 to 220 kV / mm. The impulse voltage breakdown value was measured by using a sample similar to the case of the dielectric constant, and increasing the pressure with a brass (25 mmφ) JIS type electrode while applying a negative impulse in steps of 2 kV / 3 times on a copper plate.

When the molecularly oriented molded article used in the present invention is an ultrahigh molecular weight ethylene / α-olefin polymer molecular oriented molded article, the molecular oriented molded article has impact resistance, breaking energy and creep resistance. Has the characteristic that it is remarkably excellent. These ultra-high molecular weight ethylene
The characteristics of the molecular orientation molded product of the α-olefin copolymer are represented by the following physical properties.

Ultra high molecular weight ethylene α- used in the present invention
The breaking energy of the molecular orientation molded product of the olefin copolymer is at least 8 kg · m / g, preferably at least 10 kg · m / g.

The ultra-high molecular weight ethylene / α-olefin copolymer molecular orientation molding used in the present invention has excellent creep resistance. In particular, it is remarkably excellent in creep resistance at high temperatures corresponding to the condition for promoting normal temperature creep, and is obtained as a 30% breaking load, an atmosphere temperature of 70 ° C., and an elongation (%) after 90 seconds. Creep is 7% or less, especially 5% or less, and the creep rate (ε, sec ⁻¹ ) after 90 seconds to 180 seconds is 4 × 10
^-4 sec ^-1 or less, particularly 5 × 10 ^-5 sec ^-1 or less.

Among the molecular orientation bodies used in the present invention, the ultra-high molecular weight ethylene / α-olefin copolymer molecular orientation body has the above-mentioned ordinary temperature properties. It is preferable to have the above thermal properties, because the above-mentioned physical properties are further improved and the heat resistance is also excellent.

The ultra-high molecular weight ethylene used in the present invention
The molecular orientation molded product of the α-olefin copolymer is at least 20 ° C. lower than the intrinsic crystal melting temperature (Tm) of the copolymer.
At elevated temperatures, at least one crystal melting peak (Tp)
Is 15% or more, preferably 20% or more, especially 30% or more.

The original crystal melting temperature (Tm) of the ultra-high molecular weight ethylene copolymer is determined by completely melting the molded product once, cooling it, relaxing the molecular orientation in the molded product, and then raising the temperature again. , A second run in a so-called differential scanning calorimeter.

More specifically, in the molecularly oriented molded article used in the present invention, no crystal melting peak exists at all in the crystal melting temperature range inherent to the above-mentioned copolymer, or very little, if any, tailing. It only exists. The crystal melting peak (Tp) is generally in the temperature range Tm
+ 20 ° C to Tm + 50 ° C, especially Tm + 20 ° C to Tm + 1
It is usually represented in the region of 00 ° C., and this peak (Tp) often appears as a plurality of peaks within the above temperature range. That is, this crystal melting peak (T
p) 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.
Low-temperature side melting peak (Tp ₂ ) at ℃-Tm + 35 ℃
In many cases, Tp ₁ and Tp ₂ may further comprise a plurality of peaks depending on the production conditions of the molecularly oriented molded article.

These high crystal melting peaks (Tp ₁ , T
p ₂ ) significantly improves the heat resistance of the molecularly oriented molded product of the ultrahigh molecular weight ethylene / α-olefin copolymer and contributes to the strength retention or elastic modulus retention after a high-temperature heat history. It appears to be.

Temperature range Tm + 35 ° C. to Tm + 100
The sum of the heats of fusion based on the high-temperature side melting peak (Tp ₁ ) at 150 ° C. is desirably 1.5% or more, particularly 3.0% or more, based on the total heat of fusion.

As long as the sum of the heats of fusion based on the high-temperature side melting peak (Tp ₁ ) satisfies the above-mentioned value, when the high-temperature side melting peak (Tp ₁ ) does not appear as a main peak, ie, Even if an aggregate of small peaks or a broad peak is formed, 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 determined by a differential scanning calorimeter as follows. As a differential scanning calorimeter, DSC II type (manufactured by PerkinElmer) was used. The sample was restrained in the orientation direction by winding about 3 mg on an aluminum plate having a size of 4 mm × 4 mm and a thickness of 0.2 mm. Next, the sample wound around the aluminum plate was sealed in an aluminum pan to obtain a sample for measurement. The same aluminum plate used for the sample was sealed in a normally empty aluminum pan to be placed in the reference holder, and the heat balance was maintained. First, the sample was held at 30 ° C. for about 1 minute, and then heated up to 250 ° C. at a rate of 10 ° C./min, thereby completing the first melting point measurement at the time of temperature rise. Subsequently, the temperature was kept at 250 ° C. for 10 minutes, then the temperature was lowered at a rate of 20 ° C./min, and the sample was kept at 30 ° C. for 10 minutes. Next, the second heating was performed at a heating rate of 10 ° C./min.
The temperature was raised to 50 ° C. At this time, the melting point measurement at the time of the second temperature rise (second run) was completed. At this time, the maximum value of the melting peak was defined as the melting point. When it appeared as a shoulder, a tangent was drawn at the inflection point immediately on the low temperature side and the inflection point immediately on the high temperature side of the shoulder, and the intersection point was taken as the melting point.

The intrinsic melting point of the ultrahigh molecular weight ethylene copolymer (Tm), which is obtained by connecting the points of 60 ° C. and 240 ° C. in the endothermic curve and as the main melting peak at the time of the second heating, is obtained. ) A perpendicular line is drawn at a point 20 ° C. higher than that, the lower temperature part surrounded by these is based on the original crystal melting (Tm) of the ultrahigh molecular weight ethylene copolymer, and the higher temperature part is used in the present invention. Based on the crystal melting (Tp) that expresses the function of the molecular orientation molded product to be obtained, the heat of crystal melting was calculated from these areas. In addition, the heat of fusion based on the melting of Tp ₁ and Tp ₂ was also determined in accordance with the above-described method, with the perpendicular from Tm + 20 ° C.
A portion surrounded by a vertical line from m + 35 ° C. was calculated in the same manner as a portion having a heat of fusion based on the melting of Tp ₂ , and a portion on the high temperature side having a heat of fusion based on the melting of Tp ₁ .

The ultrahigh molecular weight ethylene used in the present invention
The drawn filament of the α-olefin copolymer is 170
95% strength retention after 5 minutes heat history
As described above, the modulus of elasticity retention is 90% or more, particularly 95% or more, and has excellent heat resistance which is not recognized at all in a conventional drawn filament of polyethylene.

Molecular orientation molding of ultra-high molecular weight polyolefin
A method for producing a stretched ultra-high molecular weight polyolefin having high elasticity and high tensile strength as described above is disclosed in, for example,
-15408, JP-A-58-5228, JP-A-59-130313, JP-A-59-1876.
As described in detail in Japanese Patent Publication No. 14, etc., the ultra-high molecular weight polyethylene is made into a dilute solution, or a low molecular weight compound such as paraffin wax is added to the ultra-high molecular weight polyethylene to increase the stretchability of the ultra-high molecular weight polyethylene. An improved method of stretching at a high magnification can be exemplified.

Ultra high molecular weight ethylene / α-olefin copolymer
The manufacturing process then the invention of molecular orientation molding of polymer, its understanding for ease, the raw material will be described below in the order of manufacturing process.

The raw material used in the present invention ultrahigh molecular weight ethylene · alpha-olefin copolymer, ethylene and having 3 or more alpha-olefin carbon, using a Ziegler catalyst, for example to slurry polymerization in an organic solvent It can be obtained by:

The α-olefin having 3 or more carbon atoms includes
Propylene, butene-1, pentene-1, 4-methylpentene
-1, hexene-1, heptene-1, octene-1 and the like are used, among which butene-1, 4-methylpentene-1,
Hexene-1 and octene-1 are preferred. Such α
-The olefin is copolymerized with ethylene such that it is present in the amount described above per 1000 carbon atoms of the resulting copolymer. In addition, the ultrahigh molecular weight ethylene / α-olefin copolymer used as a base when producing a molecular alignment body in the present invention should have a molecular weight corresponding to the intrinsic viscosity [η] described above.

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

Production Method In the present invention, a diluent is added to the above-mentioned ultrahigh molecular weight ethylene / α-olefin copolymer when producing a molecularly oriented product from the copolymer. As such a diluent, a solvent for the ultrahigh molecular weight ethylene copolymer or various waxy substances having dispersibility in the ultrahigh molecular weight ethylene copolymer are used.

As such a solvent, a solvent having a boiling point higher than the melting point of the copolymer, more preferably a boiling point higher by 20 ° C. than the melting point of the copolymer is used.
As such a solvent, specifically, n-nonane, n-decane, n-undecane, n-dodecane, n-tetradecane, n-
Octadecane or liquid hydrocarbon solvents such as liquid paraffin and kerosene; xylene, naphthalene, tetralin,
Butylbenzene, p-cymene, cyclohexylbenzene,
Diethylbenzene, ventilbenzene, dodecylbenzene, bicyclohexyl, decalin, methylnaphthalene,
Aromatic hydrocarbon solvents such as ethylnaphthalene or hydrogenated derivatives thereof; 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1,2,3-trichloropropane, dichlorobenzene, 1,2,4 -Halogenated hydrocarbon solvents such as trichlorobenzene and bromobenzene; paraffinic process oils, naphthenic process oils,
Mineral oils such as aromatic process oils are exemplified.

As the wax as a diluent,
Specifically, an aliphatic hydrocarbon compound or a derivative thereof is used. As such an aliphatic hydrocarbon compound, a compound called a paraffin-based wax mainly containing a saturated aliphatic hydrocarbon compound and having a molecular weight of 2,000 or less, preferably 1,000 or less, more preferably 800 or less is used.

Specific examples of such an aliphatic hydrocarbon compound include n-alkanes having 22 or more carbon atoms such as docosane, tricosan, tetracosane, and triacontane, and lower n-alkanes containing these as main components. Mixture, so-called paraffin wax separated and refined from petroleum, medium or low pressure polyethylene wax, high pressure polyethylene wax which is a low molecular weight polymer obtained by copolymerizing ethylene or ethylene and other α-olefin,
Waxes obtained by lowering the molecular weight of ethylene copolymer wax or polyethylene such as medium / low pressure polyethylene and high pressure polyethylene by thermal degradation, oxides of these waxes, oxidized waxes such as maleic acid modified, maleic acid modified wax, etc. Is used.

As the aliphatic hydrocarbon compound derivative, for example, one or more, preferably one to two, particularly preferably one, terminal or internal terminal of an aliphatic hydrocarbon group (alkyl group, alkenyl group). A carboxyl group, a hydroxyl group, a carbamoyl group, an ester group, a meltcapto group, a compound having a functional group such as a carbonyl group, a fatty acid having 8 or more carbon atoms, preferably 12 to 50 carbon atoms or 130 to 2000 or preferably 200 to 800 carbon atoms,
An aliphatic alcohol, a fatty acid amide, a fatty acid ester, an aliphatic mercaptan, an aliphatic aldehyde, an aliphatic ketone, or the like is used.

Examples of such aliphatic hydrocarbon compound derivatives include fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and oleic acid, lauric alcohol, myristyl alcohol, cetyl alcohol, and the like. Examples thereof include aliphatic alcohols such as stearyl alcohol, fatty acid amides such as caprinamide, laurinamide, palmitamide, and stearylamide, and fatty acid esters such as stearyl acetate.

The ultrahigh molecular weight ethylene / α-olefin copolymer and the diluent differ depending on the type thereof, but are generally 3:97 to 80:20, especially 15:85 to 85:20.
It is used in a weight ratio of 60:40. When the amount of the diluent is smaller than the above range, the melt viscosity becomes too high, so that melt kneading and melt molding become difficult, and the obtained molded article is extremely rough, and is liable to cause stretch breakage and the like. On the other hand, when the amount of the diluent is more than the above range, melt kneading also becomes difficult, and the stretchability of the obtained molded article becomes poor.

The melt-kneading is generally performed at a temperature 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, and when the temperature is higher than the above range, the molecular weight of the ultra-high molecular weight ethylene / α-olefin copolymer decreases due to thermal degradation. However, it is difficult to obtain a molded article having an excellent high elastic modulus and high strength. The compounding may be performed by dry blending using a Henschel mixer, a V-type blender, or the like, or may be performed using a single-screw extruder or a multi-screw extruder.

Ultra high molecular weight ethylene / α-olefin copolymer
Melt molding of dope (spinning stock solution) consisting of coalescing and diluent
Is generally performed by melt extrusion molding. Specifically
Is obtained by melt-extruding the dope through a spinneret.
Thus, a drawing filament is obtained. At this time, the spinneret
Draft into the more extruded melt, i.e. in the molten state
You can also add a stretch. Die of molten resin
Extrusion speed V in the orifice ₀And of the unstretched material solidified by cooling
The ratio with the winding speed V is defined as a draft ratio by the following equation.
Can be

Draft ratio = V / V ₀ Such a draft ratio varies depending on the temperature of the mixture, the molecular weight of the ultrahigh molecular weight ethylene copolymer and the like, but can be usually 3 or more, preferably 6 or more. .

Next, the unstretched molded product of the ultrahigh molecular weight ethylene / α-olefin copolymer thus obtained is
Stretch. Stretching is performed so that at least a uniaxial molecular orientation is effectively imparted to an unstretched molded product obtained from an ultrahigh molecular weight ethylene / α-olefin copolymer.

The stretching of the unstretched molded article obtained from the ultrahigh molecular weight ethylene / α-olefin copolymer is generally from 40 to
It is carried out at a temperature of 160 ° C, especially 80-145 ° C. As a heat medium for heating and holding the unstretched molded body at the above-mentioned temperature, any of air, steam, and a liquid medium can be used. However, as a heat medium, a solvent capable of eluting and removing the diluent described above, and a liquid medium having a boiling point higher than the melting point of the molded article composition, specifically,
It is preferable to carry out a stretching operation using decalin, decane, kerosene or the like, since the above-mentioned diluent can be removed, stretching unevenness does not occur during stretching, and a high stretching ratio can be achieved.

The means for removing the diluent from the ultra-high molecular weight ethylene / α-olefin copolymer is not limited to the above-mentioned method.
The unstretched product may be treated with a solvent such as hexane, heptane, hot ethanol, chloroform, or benzene and then stretched, or the stretched product may be treated with a solvent such as hexane, heptane, hot ethanol, chloroform or benzene to form a molded product. By removing the diluent, a stretched product having a high elastic modulus and a high strength can be obtained.

The stretching operation can be performed in one stage or in two or more stages. The stretching ratio depends on the desired molecular orientation and the effect of improving the melting temperature associated therewith, but is generally 5 to 80 times, preferably 10 to 50 times.

In general, the stretching operation is preferably performed by two or more stages of multistage stretching.
The stretching operation is carried out while extracting the diluent in the extruded product at a relatively low temperature of 120 ° C.
It is preferable to perform the stretching operation of the molded body at a temperature of ° C. and at a temperature higher than the first-stage stretching temperature.

In the case of a uniaxial stretching operation, the stretching may be performed between rollers having different peripheral speeds. The thus obtained molecularly oriented molded article can be subjected to a heat treatment under constrained conditions, if desired. This heat treatment is generally between 140 and 18
At a temperature of 0 ° C., preferably 150-175 ° C., 1-20
Minutes, preferably 3 to 10 minutes. The heat treatment further promotes the crystallization of the oriented crystal part, and shifts the crystal melting temperature to a higher temperature side, improves strength and elastic modulus, and further improves creep resistance at high temperatures.

In the present invention, a racket gut is formed from such a filament-shaped molecularly oriented molded product of the ultrahigh molecular weight ethylene / α-olefin copolymer. In order to manufacture a racket gut from a filamentous molecular alignment body, a conventionally known method is employed.

At this time, the molecular orientation of the ultrahigh molecular weight ethylene / α-olefin copolymer has a moderate elongation as compared with the molecular orientation of the ultrahigh molecular weight polyethylene, and has a large knot strength. , A wide variety of knitting is possible.

[0054]

As described above, in the present invention, since a racket gut made of a molecularly oriented molded product of an ultrahigh molecular weight ethylene / α-olefin copolymer is used, it has excellent creep resistance and weather resistance. In addition, it has excellent impact resistance and fatigue resistance.

Claims (3)

(57) [Claims] 1. An intrinsic viscosity [η] of at least 5 dl / g.
And a racket comprising a molecular orientation of an ultra-high molecular weight ethylene / α-olefin copolymer having an average of 0.1 to 20 per 1000 carbon atoms in an α-olefin having 3 or more carbon atoms. Got. 2. The racket gut according to claim 1, wherein the α-olefin is butene-1, 4-methylpentene-1, hexene-1, octene-1 or decene-1. 3. The content of α-olefin is 100 carbon atoms.
The racket gut according to claim 1, wherein the average number per g piece is 0.5 to 10.