JPH086206B2 - Molecularly oriented molded product of ultra-high molecular weight ethylene / butene-1 copolymer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a molecularly oriented molded product of an ultrahigh molecular weight ethylene / butene-1 copolymer, and more particularly, to a novel crystal melting property. , A molecularly oriented molded product of an ultra-high molecular weight ethylene-butene-1 copolymer having excellent heat resistance and creep resistance, particularly a fiber.

(Prior art) Molding ultra high molecular weight polyethylene into fiber, tape, etc.,
By stretching this, it is already known to obtain a molecularly oriented molded article having a high elastic modulus and a high tensile strength.For example, JP-A-56-15408 discloses a dilute solution of ultra-high molecular weight polyethylene. Spinning and stretching the resulting filaments is described. Further, JP-A-59-130313 describes that an ultra-high-molecular-weight polyethylene and a wax are melt-kneaded, and this kneaded product is extruded, cooled and solidified, and then stretched. Further, JP-A-59-187614. Describes that the melt-kneaded product is extruded, drafted, cooled and solidified, and then stretched.

(Problems to be Solved by the Invention) By molding ultra-high molecular weight polyethylene into a fiber form and subjecting it to strong stretching, the elastic modulus and tensile strength are increased with an increase in the draw ratio. Stretched fibers are excellent in mechanical properties such as high elastic modulus and high tensile strength, light weight, water resistance, weather resistance, etc., but their heat resistance is such that the melting point of polyethylene is generally in the relatively low range of 120 to 140 ° C. The restriction that it is inside is fundamentally escaped, and when using ultra high molecular weight polyethylene fiber at high temperature,
It has the drawback that the strength retention is significantly reduced and the creep is significantly increased.

Therefore, an object of the present invention is to provide an ultra-high molecular weight polyethylene-based molecularly oriented molded product having novel crystal melting properties and having markedly improved heat resistance and creep resistance.

Another object of the present invention is to exhibit remarkably high strength retention and elastic modulus retention even when subjected to a high temperature thermal history such as heat treatment at 170 ° C. for 5 minutes, and to show remarkable creep at high temperature. It is an object of the present invention to provide an ultra-high molecular weight polyethylene-based molecularly oriented molded product which is suppressed to a low level.

(Means for Solving Problems) The present inventors have extruded an ultra-high molecular weight ethylene-butene-1 copolymer obtained by copolymerizing butene-1 with ethylene in a limited small amount, and subjected to strong stretching. When a molecular orientation molded article is obtained by using the above-mentioned molecular orientation molded article, it is possible to obtain a novel molecular orientation molded article having a phenomenon of improvement in melting temperature which is not observed in conventional polyethylene stretched molded articles.
It has been found that even when heat-treated at 0 ° C. for 5 minutes, the strength and the elastic modulus are hardly reduced, or conversely, these values are improved to have mechanical properties at high temperature. Further, it was also found that this molecularly oriented molded product has a significantly improved creep resistance while retaining the high strength and high elastic modulus peculiar to the stretched molded product of ultra-high molecular weight polyethylene.

That is, according to the present invention, the intrinsic viscosity [η] is at least
Butene-1 content is averaged per 1000 carbon atoms at 5 dl / g
A molecularly oriented molded product of 0.1 to 15 ultra high molecular weight ethylene / butene-1 copolymers, wherein the molded product has at least two crystal melting endothermic peaks when measured by a differential scanning calorimeter in a restrained state. And has at least one crystal melt at a temperature at least 20 ° C higher than the original crystal melting temperature (Tm) of the ultra-high molecular weight ethylene-butene-1 copolymer, which is determined as the main melting endothermic peak at the time of the second heating. Provided is a molecular orientation molded article, which has an endothermic peak (Tp) and has an amount of heat based on the crystal melting endothermic peak (Tp) of 15% or more based on the total amount of heat of fusion.

(Operation) The present invention is a molecular orientation molded product obtained by extrusion-molding an ultra-high molecular weight ethylene-butene-1 copolymer obtained by copolymerizing a limited amount of butene-1 with ethylene, and strongly stretching it. Then, it is based on the surprising finding that the melting point of the polymer chains constituting the molecularly oriented molded article is improved under the constraint condition.

In the present specification, the restraint state or the restraint condition means
No positive tension is applied to the molecularly oriented molded body,
It means that the ends are fixed so that free deformation is prevented.

The melting point of a polymer is associated with melting of crystals in the polymer and is generally measured as an endothermic peak temperature associated with melting of crystals in a differential scanning calorimeter. This endothermic peak temperature is constant if the type of polymer is determined, and after that,
For example, it hardly changes due to stretching treatment or cross-linking treatment, and even if it varies, the stretching heat treatment, which is well known as the most varying case, moves to a high temperature side of about 15 ° C. at most.

FIG. 1 is a raw material for an ultra-high molecular weight ethylene / butene-1 copolymer used in the present invention, FIG. 2 is a highly drawn filament of the ethylene-butene-1 copolymer, and FIG. The homopolymer raw material of polyethylene, and FIG. 4 are endothermic curves by a differential scanning calorimeter for each of the ultra-high-molecular-weight polyethylene highly drawn filaments, which are measured under the constraint conditions of the filaments. Is. Incidentally, FIG. 1 and FIG.
The endothermic curve of the raw material powder in the figure was measured by the method described in ASTM D 3418 in order to eliminate various histories during polymerization. See the examples described below for the composition of each polymer and the processing conditions of the filament.

From these results, the drawn filament of ordinary ultra-high molecular weight polyethylene shows an endothermic peak associated with crystal melting at a temperature of about 150 ° C., which is about 15 ° C. higher than the starting ultra-high molecular weight polyethylene. In the drawn filament of the ultra-high molecular weight ethylene / butene-1 copolymer according to the above, the endothermic peaks in all of them are shifted to the high temperature side by about 20 ° C or more compared with the original endothermic peaks as compared with the raw material copolymer. At the same time, it can be seen that the endothermic peak has multiple peaks as compared with the drawn filament of the homopolymer of ultra-high molecular weight polyethylene.

FIG. 5 shows the second run (second
The endothermic curve when it applies to the 2nd temperature rising measurement) after performing the measurement of a figure is shown. From the results of FIG. 5, in the case of reheating, the main peak of crystal melting appears at almost the same temperature as the melting peak temperature of the raw material ultra-high molecular weight ethylene-butene-1 copolymer. Since most of the molecular orientation in the sample disappeared during the measurement of, it was confirmed that the shift of the endothermic peak to the high temperature side in the sample in Fig. 2 is closely related to the molecular orientation in the molded body. Shows.

Further, from the comparison between FIG. 2 and FIG. 4, the multiple peaking of the endothermic peak in the sample of FIG. 2 is closely related to the presence of the branched chain caused by the incorporation of a small amount of butene-1 in the polymer chain. You can see that it is related to.

In the molecular orientation molded product of the present invention, by using a copolymer of ethylene with a small amount of butene-1, the introduction of the comonomer component of the polymer chain causes a decrease in crystallinity and a decrease in melting point. Considering the general fact that the melting point of the molecular orientation molded body is equal to or higher than the melting point of the molecular orientation molded body of ultra high molecular weight polyethylene,
And the fact that creep resistance is improved, as will be seen below, proves to be truly surprising.

In the molecularly oriented molded product of the present invention, the reason why the shift of the crystal melting temperature to the high temperature side becomes large has not yet been sufficiently clarified, but it is presumed as follows from the analysis of the above measurement results. That is, it is considered that a molecular oriented molded product of ultra-high molecular weight polyethylene has a structure in which a large number of polymer chains alternately pass through crystal parts and amorphous parts and the polymer chains are oriented in the stretching direction. In a molecular oriented molded product obtained by copolymerizing a small amount of butene-1 into polyethylene having a molecular weight, a part of the butene-1 chain introduced, that is, a part where a side chain is formed, selectively becomes an amorphous part, and It is believed that a portion of the repeating ethylene chain becomes an oriented crystal part through the crystal part. At this time, an average of 0 per 1000 carbon atoms in the polymer chain.
The number of side chains introduced in the number of 1 to 15 is concentrated in the non-crystalline portion, whereby the oriented crystallization of the repeating ethylene chain portion progresses to a large size with regularity, or the non-oriented portions of the both ends of the oriented crystalline portion grow. It is considered that the entanglement between the molecular chains in the crystal part increases and the polymer chain becomes difficult to move, so that the melting temperature of the oriented crystal part increases.

The molecular orientation molded article according to the present invention has substantially no decrease in strength as compared with an untreated article even when heat-treated at 170 ° C. for 5 minutes, and has an elastic modulus rather than that of an untreated article. It has the characteristic of improving. Furthermore, this molecularly oriented molded product is also remarkably excellent in creep resistance at high temperatures, and the creep (CR ₉₀ ) obtained by the method detailed later is determined.
However, it is 1/2 or less, especially 1/3 or less of the ordinary ultra-high molecular weight polyethylene oriented molded article, and the creep rate ε _90-180 (s
It has a surprising property that ec ^-1 ) is smaller than that of the ultra-high molecular weight polyethylene oriented molded body by about two orders of magnitude. It is considered that the remarkable improvements in these properties are derived from the novel microstructure of the oriented crystal part described above.

Ethylene butene used for the molecular orientation molded article of the present invention
One copolymer contains butene-1 in an amount of 0.1 to 1 per 1000 carbon atoms.
It is important to contain in an amount of 5, especially 0.5 to 10. That is, the ultrahigh molecular weight ethylene copolymer using butene-1 as a comonomer is superior in creep resistance as compared with the ultrahigh molecular weight ethylene copolymer containing ultrahigh molecular weight polyethylene or propylene as a comonomer. To give a molecularly oriented molded product. It is also very important that the butene-1 is contained in the above amount, and when the content is less than the above range, almost no effect of increasing the crystal melting temperature due to molecular orientation is observed, and If it exceeds the range, ethylene-butene-
The melting point of the 1-copolymer itself tends to decrease, and the effect of increasing the crystal melting temperature by the molecular orientation and the improvement of the elastic modulus tend to decrease.

It is also important that the ethylene / butene-1 copolymer has an intrinsic viscosity [η] of 5 dl / g or more, particularly 7 to 30 dl / g from the viewpoint of mechanical properties and heat resistance of the molecular orientation molded product. is there. That is, since the molecular terminals do not contribute to the fiber strength and the number of the molecular terminals is the reciprocal of the molecular weight (viscosity), it can be seen that the one having a large intrinsic viscosity [η] gives a high strength.

The molecular orientation molded article of the present invention has an ultra-high molecular weight ethylene-butene
1 At least than the crystal melting temperature (Tm) of the original copolymer
Having at least one crystal melting endotherm peak (Tp) at a temperature 20 ° C. higher, and the amount of heat based on this crystal melting endothermic peak (Tp) per total heat of fusion is 15% or more, preferably 20%, particularly 30% The above is important from the viewpoint of heat resistance of the molecularly oriented molded article, that is, retention of strength and elastic modulus at high temperature and creep resistance at high temperature.

That is, a molecularly oriented molded product that does not have a crystal melting endothermic peak (Tp) in a temperature region higher than Tm by 20 ° C. or even if it has a crystal melting endothermic peak in this temperature region, the endothermic amount based on it is the total melting heat amount. In the case of molecularly oriented molded products with less than 15% of
When heat-treated at 170 ° C. for 5 minutes, the strength retention rate and elastic modulus retention rate tend to decrease substantially, and creep and creep rate during heating tend to increase.

(Description of preferred embodiments) The present invention will be described below in the order of the raw material, the production method, and the target product for easy understanding.

Raw material The ultra high molecular weight ethylene / butene-1 copolymer used in the present invention is produced by slurry-polymerizing ethylene and butene-1 as a comonomer in the presence of a Ziegler catalyst, for example, in an organic solvent. It

In this case, the amount of butene-1 comonomer used should be such that it gives a butene-1 content in the polymer chain in the range mentioned above per 1000 carbons. Further, the ultrahigh molecular weight ethylene / butene-1 copolymer used should have a molecular weight corresponding to the above-mentioned intrinsic viscosity [η].

If the butene-1 content is less than 0.2 per 1000 carbon atoms, a structure effective for improving creep resistance cannot be formed, and conversely, the butene-1 content is 15 or more per 1000 carbon atoms. In this case, the crystallinity is remarkably lowered, and a high elastic modulus cannot be obtained. The quantification of the butene-1 component of the ultrahigh molecular weight ethylene / butene-1 copolymer in the present invention was carried out by an infrared spectrophotometer (manufactured by JASCO Corporation).
In other words, the absorbance at 1378 cm ^-1 based on the bending vibration of the methyl group at the branched end of butene-1 incorporated into the ethylene chain was measured, and from this, in advance with a ¹³ C nuclear magnetic resonance apparatus,
Easily 1000 with a calibration curve created using model compounds
It is a value measured by converting it into the number of methyl branches per carbon atom.

Manufacturing Method In the present invention, a diluent is blended with the above components in order to enable melt molding of the ultrahigh molecular weight ethylene / butene-1 copolymer. As such a diluting agent, a solvent for the ultra high molecular weight ethylene copolymer or various waxes having compatibility with the ultra high molecular weight ethylene copolymer are used.

The solvent is preferably a solvent having a boiling point not lower than the melting point of the copolymer, more preferably not lower than the melting point + 20 ° C.

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

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

Since the aliphatic hydrocarbon compound is mainly a saturated aliphatic hydrocarbon compound, it is usually called a paraffin wax having a molecular weight of 2000 or less, preferably 1000 or less, more preferably 800 or less. Specific examples of these aliphatic hydrocarbon compounds include docosane, tricosane,
N- with 22 or more carbon atoms such as tetracosane and triacontane
Alkanes or mixtures with lower n-alkanes containing them as a main component, so-called paraffin wax separated and purified from petroleum, and low molecular weight polymers obtained by copolymerizing ethylene or ethylene with other α-olefins.・
Low-pressure polyethylene wax, high-pressure polyethylene wax, ethylene copolymer wax or wax such as medium / low-pressure polyethylene, high-pressure polyethylene whose molecular weight has been reduced by thermal degradation, and oxides or maleic acid modification of these waxes Oxidized waxes, maleic acid-modified waxes and the like.

As the aliphatic hydrocarbon compound derivative, for example, one or more, preferably one or two, at the terminal or inside of the aliphatic hydrocarbon group (alkyl group, alkenyl group),
Particularly preferred is a compound having a functional group such as one carboxyl group, a hydroxyl group, a carbamoyl group, an ester group, a meltcapto group, a carbonyl group, and the like, preferably 8 or more carbon atoms, preferably 12 to 50 carbon atoms or 130 to 2000 molecular weight, preferably Is 200
To 800 fatty acids, aliphatic alcohols, fatty acid amides, fatty acid esters, aliphatic mercaptans, aliphatic aldehydes, aliphatic ketones and the like.

Specifically, as a fatty acid, capric acid, lauric acid,
Myristic acid, palmitic acid, stearic acid, oleic acid, lauric alcohol as a fatty alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, capric amide as a fatty acid amide, laurinamide, palmitinamide, stearyl amide, stearyl acetic acid ester as a fatty acid ester, etc. Can be illustrated.

The ratio of ultra high molecular weight ethylene copolymer to diluent also varies depending on these types, but generally it is 3:97.
It is advisable to use it in a weight ratio of from 80 to 20:20, in particular from 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 surface roughness of the molded product is remarkable, and stretch breakage easily occurs. 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 molded product becomes poor.

Melt kneading is generally carried out at a temperature of 150 to 300 ° C., particularly 170 to 270 ° C., and if the temperature is lower than the above range, the melt viscosity is too high, which makes melt molding difficult, and is higher than the above range. In particular, due to thermal degradation, the molecular weight of the ultra high molecular weight ethylene copolymer is lowered, and it becomes difficult to obtain a molded product having a high elastic modulus and a 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 by melt mixing using a single-screw or multi-screw extruder.

Melt molding is generally performed by melt extrusion molding. For example, by melt-extruding through a spinneret, a filament for stretching is obtained, and by extruding through a flat die or a ring die, a stretching film or sheet or tape is obtained, and further by extruding through a circular die, A stretch blow molding pipe (parison) is obtained. The invention is particularly useful for producing drawn filaments, in which case the melt extruded from the spinneret can be drafted, i.e., stretched in the molten state. Extrusion speed V ₀ of the molten resin in the die orifice and winding speed V of the unstretched material solidified by cooling
Can be defined by the following equation as a draft ratio.

Draft ratio = V / V ₀ (2) The draft ratio depends 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.

Of course, melt molding is not limited to extrusion molding, and in the case of manufacturing various stretch-molded containers and the like, it is also possible to manufacture a preform for stretch blow molding by injection molding. Cooling and solidification of the molded product can be performed by forced cooling means such as air cooling or water cooling.

The unstretched molded product of the ultrahigh molecular weight ethylene copolymer thus obtained is stretched. The degree of the stretching treatment is, of course, such that molecular orientation in at least uniaxial direction is effectively imparted to the ultrahigh molecular weight ethylene copolymer of the molded product.

The stretching of the ultra-high molecular weight ethylene copolymer molded body is preferably carried out at a temperature of generally 40 to 160 ° C, particularly 80 to 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, a solvent capable of eluting and removing the above-mentioned diluent as a heat medium and having a boiling point higher than the melting point of the molded body composition, specifically decalin, decane, kerosene, etc. By performing the above, it is possible to remove the above-mentioned diluent, and it is possible to eliminate unevenness in stretching during stretching and achieve a high stretching ratio, which is preferable.

Of course, means for removing the excess diluent from the ultra high molecular weight ethylene copolymer is not limited to the above method, hexane, heptane, hot ethanol, chloroform, a method of stretching after treating with a solvent such as benzene, Hexane,
The method of treating with a solvent such as heptane, hot ethanol, chloroform, benzene, etc. can also effectively remove the excess diluent in the molded product and obtain a stretched product with high elastic modulus and high strength.

The stretching operation can be performed in one stage or in multiple stages of two or more stages. The stretching ratio generally depends on the desired molecular orientation and the effect of improving the melting temperature accompanied therewith, but generally 5 to
Satisfactory results can be obtained by carrying out the stretching operation so that the stretching ratio is 80 times, particularly 10 to 50 times.

In general, multi-stage drawing of two or more steps is advantageous, and the drawing operation is performed while extracting the diluent in the extrusion-molded product at a relatively low temperature of 80 to 120 ° C in the first step, and in the second and subsequent steps,
It is preferable to continue 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 uniaxial stretching operation such as filament, tape or uniaxial stretching, tensile stretching may be performed between rollers having different peripheral speeds, and in the case of biaxially stretched film, longitudinal stretching may be performed between rollers having different peripheral speeds. Along with performing the tensile stretching, the tensile stretching is also performed in the transverse direction using a tenter or the like. Biaxial stretching by the inflation method is also possible. Furthermore, in the case of a three-dimensional molded product such as a container, a biaxially stretched molded product can be obtained by a combination of tensile stretching in the axial direction and expansion stretching in the circumferential direction.

The molecular orientation molded body thus obtained can be heat-treated under restrained conditions, if desired. This heat treatment is generally carried out at a temperature of 140 to 180 ° C, especially 150 to 175 ° C, for 1 to 20 ° C.
It can be carried out for minutes, in particular for 3 to 10 minutes. The heat treatment further promotes the crystallization of the oriented crystal part, which leads to the shift of the crystal melting temperature to the high temperature side, the improvement of the strength and the elastic modulus, and the improvement of the creep resistance at high temperature.

Molecularly oriented molded product As described above, the ultra high molecular weight ethylene according to the present invention
The butene-1 copolymer molecular orientation molded product has at least one crystal melting peak (Tp) at a temperature at least 20 ° C. higher than the original crystal melting temperature (Tm) of the copolymer, and has a total melting temperature. The heat of fusion based on this crystal melting peak (Tp) per heat is 15% or more, preferably 20% or more, and particularly 30% or more.

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

To explain further, in the molecular orientation 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) generally appears in the temperature range Tm + 20 ° C. to Tm + 50 ° C., and this peak (Tp) often appears as a plurality of peaks within the above temperature range.

These crystal melting peaks (Tp) in the high temperature region remarkably improve the heat resistance of the ultra-high molecular weight ethylene / butene-1 copolymer molded article, and also improve the strength retention rate after high temperature heat history and It seems to contribute to the elastic modulus retention rate.

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. 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 kept at 30 ° C. for about 1 minute, and then heated up to 250 ° C. at a rate of 10 ° C./min to complete the first melting point measurement at the time of temperature rise. Subsequently, 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 ultra-high 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 second heating A vertical 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.

The degree of molecular orientation in the molded article can be determined by an X-ray diffraction method, a birefringence method, a fluorescence polarization method, or the like. In the case of the drawn filament of the ultrahigh molecular weight ethylene copolymer of the present invention, for example, Yukichi Kure, Teruichiro Kubo: Industrial Chemistry Journal Vol. 39, 992 (1939), the degree of orientation according to the half width,
That is, the formula In the formula, H ゜ is the half width (゜) of the intensity distribution curve along the Debye ring of the strongest paratropic plane on the equator.

It is desirable in terms of mechanical properties that the molecular orientation is such that the degree of orientation (F) defined by is 0.90 or more, particularly 0.95 or more.

The drawn filament of the ultrahigh molecular weight ethylene / butene-1 copolymer of the present invention has a strength retention of 95% or more, particularly 98% or more, after being subjected to a heat history of 5 minutes at 170 ° C. The ratio is 95% or more, particularly 98% or more, and it has excellent heat resistance that is not found in conventional polyethylene stretched filaments.

In addition, this drawn filament is outstandingly excellent in creep resistance at high temperatures, and the load is 30% breaking load,
Creep calculated as extension (%) after 90 seconds is 7% or less, especially 5% or less when the ambient temperature is 70 ° C, and the creep speed (ε, sec ^-1 ) after 90 seconds to 180 seconds is 1 × 10 ^-4 sec
^-1 or less, especially 5 × 10 ^-4 sec ^-1 or less.

Furthermore, the molecularly oriented molded product of the ultrahigh molecular weight ethylene / butene-1 copolymer according to the present invention is also excellent in mechanical properties, for example, in the form of a stretched filament, an elastic modulus of 20 GPa or more, particularly 30 GPa or more, and 1.2 GPa. Above, in particular, has a tensile strength of 1.5 GPa or more.

The ethylene-butene-1 copolymer fiber according to the present invention is
When a load that is slightly smaller than the breaking load is applied at room temperature,
It has the characteristic that the time to break is extremely long. That is, these fibers have a breaking time (T ₁ hour) when a load (F) of 750 to 1500 MPa is applied at room temperature. Owns a patent. The breaking time (T) of ultra-high molecular weight homopolyethylene fibers and ethylene-propylene copolymer fibers is considerably shorter than that of the above.

<Measurement of Creep Rupture Time> The creep rupture time was determined as follows. Sample length approx.
Make a 100cm distance between the marked lines from the center of the 150cm sample, and put the marked lines. A desired load is applied to the sample under the conditions of an ambient temperature of 23 ° C and a relative humidity of 55%. The creep rupture time is measured by measuring the elapsed time from immediately after the application to the rupture. The minimum breaking time is 1 in 6 measurements, excluding those that break outside the marked line.
Except the measurement, the average creep rupture time of 5 measurements is used as the measured value.

(Effects of the Invention) The molecularly oriented molded product of the ultrahigh molecular weight ethylene / butene-1 copolymer of the present invention is excellent in the combination of heat resistance, creep resistance and mechanical properties. Thus, by utilizing this characteristic, the molecularly oriented molded article of the present invention is useful as a packaging material such as a packaging tape, in addition to industrial textile materials such as high-strength multifilaments, strings, ropes, woven fabrics and nonwoven fabrics. Is.
In addition, a molded product in the form of a filament is made of epoxy resin,
When it is used as a reinforcing fiber for various resins such as unsaturated polyester and synthetic rubber, it is clear that the heat resistance and creep resistance are significantly improved as compared with the conventional ultra high molecular weight polyethylene drawn filament. Ah
In addition, since this filament has high strength and low density, it is particularly effective because it can be made lighter than conventional molded articles using glass fiber, carbon fiber, boron fiber, aromatic polyamide fiber, aromatic polyimide fiber, etc. Is. Similar to composite materials using glass fiber, etc., UD (Unit Directi
onal) laminated board, SMC (Sheet Molding Compound), BMC
(Bulk Molding Compound) can be molded, and it is expected to be used for various composite materials in the fields of light weight and high strength such as automobile parts, boat and yacht structures, and electronic circuit boards.

Example 1 <Polymerization of Ultra High Molecular Weight Ethylene / Butene-1 Copolymer> A slurry polymerization of an ultra high molecular weight ethylene / butene-1 copolymer was carried out using a Ziegler type catalyst and n-decane 1 as a polymerization solvent. The composition of ethylene and butene-1 has a molar ratio of 97.2: 2.86 mixed monomer gas at a pressure of 5 Kg / c.
The reactor was continuously fed so that a constant pressure of m ² was maintained, and the polymerization was completed at a reaction temperature of 70 ° C. for 2 hours. The yield of the ultra-high molecular weight ethylene-butene-1 copolymer powder obtained was 145 g, the intrinsic viscosity (decalin: 135 ° C.) was 7.25 dl / g, and the butene-1 content by an infrared spectrophotometer was 4.7 per 1000 carbon atoms. It was an individual.

<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 oriented. Then, the mixture was screw-type extruder (screw diameter: 25 mm, L / D = 25, manufactured by Thermoplastics Co., Ltd.)
Was melt-kneaded at a set temperature of 190 ° C. Then, the orifice diameter 2 mm attached to the extruder
Melt spinning was carried out from the spinning die. 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 was n-decane, and the temperature was 11
The heating medium in the second stretching tank was 0 ° C., triethylene glycol was used, and the temperature was 145 ° C. The effective length of each tank is 50 cm
Met. At the time of drawing, 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. Thereafter, the oriented fibers were washed with water, dried at room temperature under reduced pressure for a day and night, and subjected to 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 100
It was 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 Heat History> The heat 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 tensile properties described above.

<Measurement of creep resistance> Using a thermal stress strain measurement device TMA / SS10 (manufactured by Seiko Denshi Kogyo Co., Ltd.), the creep characteristics were measured using a sample length of 1 cm, an ambient temperature of 70 ° C, and a load of 30% of the breaking load at room temperature. Was performed under accelerated conditions of a weight corresponding to The following two values were obtained to quantitatively evaluate the amount of creep. That is, the sleep elongation% after 90 seconds after loading is CR ₉₀ , and the average creep rate (sec ⁻¹ ) ε from 90 seconds to 180 seconds.

 Table 1 shows the tensile properties of the obtained oriented fiber.

FIG. 2 shows the endothermic characteristic curve of Sample 1 measured by the differential scanning calorimeter during the first temperature increase, and FIG. 5 shows the endothermic characteristic curve during the second temperature increase (second run). The original crystal melting peak of the ultra-high molecular weight ethylene / butene-1 copolymer stretched and oriented fiber (Sample-1) was 126.9 ° C, and the ratio of Tp to the total crystal melting peak area was 33.7%. The creep resistance was CR ₉₀ = 3.2% and ε = 3.03 × 10 ^-5 . The creep characteristics of Sample 1 are shown in FIG. 170 ° C, 5
The elastic modulus retention rate after 10 minutes heat history was 101.2%, the strength retention rate was 102.7%, and there was no decrease in performance due to heat history.

Example 2 <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 98.7: 1.3 was used at a pressure of 5 Kg /
The reactor was continuously fed so as to maintain a constant pressure of cm ² . The polymerization was completed in 2 hours at a reaction temperature of 70 ° C. The yield of the obtained ultra high molecular weight ethylene / butene-1 copolymer powder was 179 g,
Its intrinsic viscosity [η] (decalin, 135 ° C) was 9.4 dl / g, and the butene-1 content by an infrared spectrophotometer was 1.5 per 1000 carbon atoms.

<Preparation and Properties of Ultra-High Molecular Weight Ethylene / Butene-1 Copolymer Stretched Alignment> Ultra-high molecular weight ethylene / butene-obtained by the above polymerization
Ultra-high molecular weight ethylene / butene-1 copolymer stretch-oriented fibers were prepared in the same manner as in Example 1 using 1 copolymer powder. Table 2 shows the tensile properties of the obtained oriented fiber.

FIG. 6 shows the endothermic characteristic curve of the ultra-high molecular weight ethylene / butene-1 copolymer stretch-oriented fiber sample 2 at the first temperature increase by the differential scanning calorimeter, and at the second temperature increase (second run). The endothermic characteristic curve of is shown in FIG. The original crystal melting peak of the ultra-high molecular weight ethylene / butene-1 copolymer stretched and oriented fiber (Sample 2) was 129.8 ° C., and the ratio of Tp to the total crystal melting peak area was 38.9%.

The creep resistance was CR ₉₀ = 1.29% and ε = 1.21 × 10 ^-5 . The creep characteristics of Sample-2 are shown in FIG.
Furthermore, the elastic modulus retention rate after thermal history at 170 ° C for 5 minutes is 100.3.
%, The strength retention was 103.0%, and there was no deterioration in performance due to thermal history.

Table 3 shows the relationship between the applied load and the creep rupture time of Sample-2.

Figure 13 shows the relationship between applied load and fracture time at room temperature.

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): 80 parts by weight The mixture was melt-spun and stretched by the method of Example 1 to obtain oriented stretched fibers. Table 4 shows the tensile properties of the obtained stretched and oriented fibers.

Figure 4 shows the endothermic characteristic curve of the ultra-high molecular weight stretched polyethylene oriented fiber (Sample 3) at the first temperature increase by the differential scanning calorimeter, and at the second temperature increase (second run). Is shown in FIG. The original crystal melting peak of the ultrahigh molecular weight polyethylene sample 3 was 135.1 ° C, and the ratio of Tp to the total crystal melting peak area was 8.8%. Similarly, the peak Tp ₁ on the high temperature side with respect to the total crystal melting peak area
Was 1.0%. Creep resistance is CR ₉₀ = 12.
0% and ε = 1.07 × 10 ⁻³ sec ⁻¹ . The creep characteristics of Sample 3 are shown in FIG. 9 together with Sample 1 and Sample 2. 17 more
The elastic modulus retention rate after heat history at 0 ° C. for 5 minutes was 80.4%, and the strength retention rate was 79.2%, and the elastic modulus and strength decreased due to the thermal history.

Comparative Example 2 Ultrahigh molecular weight polyethylene (homopolymer) powder (intrinsic viscosity [η] = 10.2 dl / g, decalin, 135 ° C.): 20 parts by weight and paraffin wax (melting point = 69 ° C., molecular weight = 490): 80 parts by weight The mixture was melt-spun by the method described in Example 1 and stretched to obtain a stretched / blended fiber. Table 5 shows the tensile properties of the obtained stretched and oriented fibers.

The endothermic characteristic curve of the ultrahigh molecular weight polyethylene stretch-oriented fiber sample-4 at the first temperature rising was measured by the differential scanning calorimeter.
Shown in the figure, and FIG. 12 shows the endothermic characteristic curve during the second temperature rise (second run). Ultra high molecular weight polyethylene fiber sample-4 The original crystal melting peak was 135.5 ° C, and the ratios of T _P and T _P1 to the total crystal melting peak area were 13.8 each.
% And 1.1%. Creep resistance of sample-4 is CR
₉₀ = 8.2% and ε = 4.17 × 10 ⁻⁴ sec ⁻¹ . Figure 12 shows the creep characteristics of Sample-4. Furthermore, the elastic modulus retention rate after heat history at 170 ° C for 5 minutes is 86.1%, and the strength retention rate is 93.1%.
In particular, the elastic modulus was remarkably reduced.

Table 6 shows the relationship between the applied load and the creep rupture time of Sample-4.

The relationship between the applied load and the breaking time at room temperature is shown in Fig. 13 together with that of Sample-2.

[Brief description of drawings]

FIG. 1 is an endothermic characteristic curve of the ultrahigh molecular weight ethylene / butene-1 copolymer powder used in Example 1 obtained by a differential scanning calorimeter, and FIG. 2 is the ultrahigh molecular weight ethylene / butene-1 obtained in Example 1. 1 Endothermic characteristic curve by differential scanning calorimeter in the constrained state of stretched oriented fiber of copolymer, FIG. 3 is an endothermic characteristic curve by differential scanning calorimeter of ultra high molecular weight polyethylene powder used in Comparative Example 1, and FIG. 4 is Endothermic characteristic curve of the drawn ultra high molecular weight polyethylene oriented fiber obtained in Comparative Example 1 by a differential scanning calorimeter in a restrained state. Fig. 5 shows the sample of Fig. 2 subjected to the second temperature rise measurement (second run). 6 is an endothermic characteristic curve of the ultra-high molecular weight ethylene / butene-1 copolymer stretched oriented fiber obtained in Example 2 in a restrained state by a differential scanning calorimeter, and FIG. The sample of Fig. 6 was measured for the second temperature rise. 8 is an endothermic characteristic curve when the sample of FIG. 4 is subjected to a second temperature rise measurement, and FIG. 9 is an example 1, an example 2 and a comparative example. The creep characteristic curve of the stretch-oriented fiber of each polymer obtained in 1 is shown. FIG. 10 shows an endothermic characteristic curve of the drawn ultra-high molecular weight polyethylene oriented fiber obtained in Comparative Example 2 in a restrained state by a differential scanning calorimeter, and FIG. 11 shows the sample of FIG. FIG. 12 shows the endothermic characteristic curve of the drawn oriented fiber obtained in Comparative Example 2. FIG. 13 is a diagram showing the relationship between the applied load at room temperature and the breaking time for each of the fibers of Sample-2 and Sample-4.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area C08F 210/16 MJM

Claims (2)

[Claims] 1. A molecular orientation molding of an ultrahigh molecular weight ethylene-butene-1 copolymer having an intrinsic viscosity [η] of at least 5 dl / g and an average content of butene-1 of 0.1 to 15 per 1000 carbon atoms. A body, the molded body being constrained, when measured by a differential scanning calorimeter,
Having at least two crystalline melting endotherms,
Ultrahigh molecular weight ethylene-butene-1 copolymer, which is determined as the main melting endothermic peak during the second heating, has a temperature of at least 20 ° C higher than the original crystal melting temperature (Tm) of the ultrahigh molecular weight ethylene-butene-1 copolymer.
It has one crystal melting endothermic peak (Tp), and the calorific value based on this crystal melting endothermic peak (Tp) per total heat of fusion is 15
% Or more, a molecular orientation molded article. 2. A molecular orientation molded article according to claim 1, wherein the content of butene-1 is 0.5 to 10 on average per 1000 carbon atoms.