JPS63275710A - Molecularly oriented molded product of ultrahigh-molecular weight ethylene-alpha-olefin copolymer - Google Patents

Abstract

PURPOSE:To obtain a molecularly oriented molded product of the titled copolymer having a specific intrinsic viscosity and alpha-olefin content, plural and high endothermic peaks of crystal melting within a higher temperature region, excellent heat and creep resistance and useful as industrial textile materials, etc. CONSTITUTION:Ethylene and an alpha-olefin (e.g. 4-methylpentene-1) are polymerized as a slurry in n-decane as a polymerization solvent using a Ziegler based catalyst to provide a copolymer, which is then melt spun and drawn to afford the aimed molecularly oriented molded product having >=5dl/g intrinsic viscosity [eta], average 0.1-15 alpha-olefin content based on 1,000 carbon atoms, >=2 endothermic peaks of crystal melting when measured in a restricted state thereof using a differential scanning calorimeter, >=1 main endothermic peaks (Tp) of crystal melting at a temperature 20 deg.C higher than the original crystal melting temperature (Tm) obtained as the main endothermic peak of melting in the second heating and >=15% quantity of heat based on the Tp for the total heat quantity of melting.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a molecularly oriented molded product of an ultra-high molecular weight ethylene-α-olefin copolymer, and more specifically to a molded product having novel crystal melting properties. , relates to a molecularly oriented molded article of an ultra-high molecular weight ethylene-α-olefin copolymer having excellent heat resistance and creep resistance, particularly to fibers.

(Prior art) It is already well known that ultra-high molecular weight polyethylene is formed into fibers, tapes, etc. and stretched to produce molecularly oriented molded products with high elastic modulus and high tensile strength. , JP-A-56-15408 describes spinning a dilute solution of ultra-high molecular weight polyethylene and drawing the resulting filament. Also, JP-A-59-1
No. 30313 describes that ultra-high molecular weight polyethylene and wax are melt-kneaded, the mixed material is extruded, cooled and solidified, and then stretched.
No. 4 describes that the above melt-kneaded product is extruded, drafted, cooled and solidified, and then stretched.

(Problems to be Solved by the Invention) By forming ultra-high molecular weight polyethylene into a fiber form and subjecting it to strong stretching, the elastic modulus and tensile strength can be increased as the stretching ratio increases. Stretched fibers have mechanical properties such as high elastic modulus and high tensile strength, light weight, water resistance,
Although it has excellent weather resistance, its heat resistance is fundamentally limited by the fact that the melting point of polyethylene is generally within a relatively low range of 120 to 140°C. When used at high temperatures, there are drawbacks such as a significant decrease in strength retention and a significant increase in IJ-p.

Therefore, it is an object of the present invention to have novel crystal melting properties,
It is an object of the present invention to provide a molecularly oriented ultra-high molecular weight polyethylene molded article having significantly improved heat resistance and creep resistance.

Another object of the present invention is to exhibit significantly high strength retention and elastic modulus retention even when subjected to high-temperature thermal history such as heat treatment at 170°C for 5 minutes, and to exhibit significantly low creep at high temperatures. Ultra-high molecular weight/IJ suppressed to a low level
An object of the present invention is to provide an ethylene-based molecularly oriented molded product.

(Means for Solving the Problem) The present inventors have developed an ultra-high molecular weight ethylene-α-olefin copolymer in which a limited amount of α-olefin having 5 or more carbon atoms is copolymerized with ethylene. When molded and strongly stretched to obtain a molecularly oriented molded product, a novel molecularly oriented molded product can be obtained which exhibits an improvement in melting temperature that is completely unobservable in the conventional stretched 4-lyethylene molded product, and this molecular orientation It has been found that the molded product has mechanical properties at high temperatures such that the strength and elastic modulus hardly decrease or, conversely, these values improve even when heat treated at 170° C. for 5 minutes. Furthermore, it has been found that this molecularly oriented molded product has significantly improved creep resistance while retaining the high strength and high modulus characteristic of a stretched molded product of ultra-high molecular weight polyethylene.

That is, according to the present invention, the intrinsic viscosity [η] is at least 5
dt/i, the content of α-olefins having 5 or more carbon atoms is on average 0.1 to 15 per 1000 carbon atoms; , the molded body has at least two crystal melting endothermic peaks when measured with a differential scanning calorimeter in a restrained state, and has ultra-high molecular weight ethylene-α- which is determined as the main melting endothermic peak at the second heating. at least one crystal melting endothermic peak (Tp) at a temperature at least 20°C higher than the original crystal melting temperature (Tm) of the olefin copolymer;
), and the amount of heat based on this crystal melting endothermic peak (Tp) K per total heat of fusion is provided.

(Function) The present invention provides a limited amount of α-olefin (C3 or more)
When an ultra-high molecular weight ethylene-α-olefin copolymer obtained by copolymerizing with ethylene is extruded and strongly stretched to form a molecularly oriented molded product, the melting point of the polymer chains constituting the molecularly oriented molded product increases. This is based on the surprising finding that performance improves under restraint conditions.

In this specification, the term "restricted state" or "restricted condition" means that no active tension is applied to the molecularly oriented molded product, but the ends are fixed so as to prevent free deformation. .

The melting point of a polymer is associated with the melting of crystals in the polymer, and is generally measured as the endothermic peak temperature associated with crystal melting using a differential scanning calorimeter. This endothermic peak temperature is
The type of polymer remains the same, and it hardly changes due to subsequent treatments such as stretching or crosslinking. Even with heat treatment, the temperature only moves to the high temperature side by about 15°C at most.

The attached drawings, Figure 1, show the ultra-high molecular weight engineered tyrene-4-methylpentene-x copolymer (K-4MP) raw material used in the present invention;
Figure 2 is a differential scan of highly drawn filaments of this copolymer (E-4MP), Figure 3 is a normal ultra-high molecular weight polyethylene raw material, and Figure 4 is a differential scan of highly drawn filaments of this ultra-high molecular weight polyethylene. This is an endothermic curve measured by a calorimeter, and the endothermic curve of the highly drawn filament was measured under filament restraint conditions. For the composition of each polymer and the processing conditions for filaments, please refer to the examples described later.

The endothermic curves of the raw material powders shown in Figures 1 and 3 were measured in accordance with ASTM D 34 in order to eliminate various heat histories during polymerization.
The method described in 18 was used.

From these results, it is clear that the drawn filament of ordinary ultra-high molecular weight polyethylene exhibits an endothermic peak associated with crystal melting at a temperature of about 150°C, which is about 15°C higher than the ultra-high molecular weight polyethylene used as the raw material. In the drawn filaments of ultra-high molecular weight ethylene-α-olefin copolymer, the endothermic peak shifted significantly to the high temperature side compared to the raw material copolymer, and It can be seen that the endothermic peak is located on the considerably higher temperature side compared to the drawn filament.

FIG. 5 shows endothermic curves obtained when the samples shown in FIG. 2 were subjected to a second run (second temperature-raising measurement after the measurement shown in FIG. 2 was performed). From the results shown in Figure 5, in the case of reheating, the main peak of crystal melting is the ultra-high molecular weight ethylene-4-
It appears at almost the same temperature as the melting peak temperature of the methylpentene-1 copolymer, and moreover, the molecular orientation in the sample had almost disappeared at the time of the measurement in Figure 5, so the This indicates that the shift of the endothermic peak toward higher temperatures is closely related to the molecular orientation in the compact.

Furthermore, from the comparison between Figure 2 and Figure 4, the shift of the endothermic peak to the higher temperature side in the sample in Figure 2 is due to the branching caused by the incorporation of a small amount of C6 or higher α-olefin into the polymer chain. It can be seen that this is closely related to the presence of chains.

Molecularly oriented molded product Kj of the present invention? The fact that the endothermic peak shifts to the high temperature side when ethylene is copolymerized with a small amount of α-olefin having 5 or more carbon atoms is due to the fact that the comonomer in the polymer chain This is truly surprising considering the general fact that the introduction of mercury components leads to a decrease in crystallinity and a decrease in melting point.

Although the reason why the crystal melting temperature shifts to the higher temperature side in the molecularly oriented molded product of the present invention has not yet been fully elucidated, it is estimated as follows from the analysis of the measurement results described above. That is, in a molecularly oriented molded product of ultra-high molecular weight polyethylene, it is thought that a large number of polymer chains have a structure in which they alternately pass through crystalline parts and amorphous parts, and the polymer chains are oriented in the stretching direction. In the molecularly oriented molded product obtained by copolymerizing a small amount of α-olefin such as 4-methylpentene-1 into high molecular weight polyethylene, the portion of the introduced α-olefin chain, that is, the portion where the side chain is formed, is selected. It is believed that the repeating ethylene chain becomes an oriented crystalline part via this amorphous part. At this time, the side chain moieties introduced into the polymer chain at an average number of 0.1 to 15 per 1000 carbon atoms concentrate in the amorphous part, which makes the oriented crystallization of the repeating ethylene chain more regular. The melting temperature of the oriented crystal part increases because the polymer chain progresses to a large size with good stability, or the entanglement between molecular chains increases in the amorphous parts at both ends of the oriented crystal part, making it difficult for the polymer chains to move. Seem.

Even when the molecularly oriented molded product of the present invention is heat-treated at 170°C for 5 minutes, there is virtually no decrease in strength compared to the untreated product, and the elastic modulus is considerably lower than that of the untreated product. It has the characteristic of improving. Furthermore, this molecularly oriented molded product also had remarkable high-temperature cleaving resistance, and the cleave (CR) was determined by the method described in detail later.

) is 1/1 of that of a normal ultra-high molecular weight polyethylene oriented molded product.
2 or less, and the creep rate is 6. . -48° (5e
e-') is smaller than that of an ultra-high molecular weight polyethylene oriented molded product by more than two orders of magnitude, which is a surprising property. It is believed that these remarkable improvements in properties are due to the novel microstructure of the oriented crystal parts mentioned above.

The ethylene-α-olefin copolymer used in the molecularly oriented molded article of the present invention contains 0.1 to 15 α-olefins, particularly 0.5 to 1 α-olefin, per 1000 carbon atoms.
It is important to contain the amount of 0 pieces. That is, carbon number 5
Copolymers using the above α-olefins have a carbon number of 5
The present invention provides a molecularly oriented molded article having particularly excellent creep resistance compared to ethylene copolymers using smaller α-olefins such as ultra-high molecular weight polyethylene and propylene.

This is thought to be because the long side chains present in the amorphous portion make it more difficult for the polymer chain to move at high temperatures. This α
- It is extremely possible to contain the above amount of olefin! ! If the content is less than the above range,
There is almost no effect of increasing the crystal melting temperature due to molecular orientation, and if it is 4 higher than the above range, the melting point of the ethylene-α-olefin copolymer itself tends to decrease, and the crystal melting temperature due to molecular orientation increases. The effect of increasing the melting temperature and the elastic modulus also tend to decrease.

Further, this ethylene-α-olefin copolymer has an intrinsic viscosity [η] of 5 dt/I or more, particularly 7 to 7.

Being in the range of 30 dt/I is also important from the viewpoint of mechanical properties and heat resistance of the molecularly oriented molded product. That is, since molecular terminals do not contribute to fiber strength and the number of molecular terminals is the reciprocal of the molecular weight (viscosity), it can be seen that a material with a large intrinsic viscosity [η] gives high strength.

The molecularly oriented molded product of the present invention is heated to a temperature at least 20°C higher than the original crystal melting temperature (Tm) of the ultra-high molecular weight ethylene-α-olefin copolymer, which is determined as the main melting endothermic peak during the second heating. Molecular orientation molding It is important in terms of the heat resistance of the body, that is, the ability to maintain strength and elastic modulus at high temperatures, and the creep resistance at high temperatures.

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

(Description of Preferred Embodiments) The present invention will be described below in order of raw materials, manufacturing method, and object for easy understanding.

Raw materials The ultra-high molecular weight ethylene-α-olefin copolymer used in the present invention can be obtained by slurry polymerizing ethylene and an α-olefin having 5 or more carbon atoms as a comonomer using a Ziegler catalyst, for example, in an organic solvent. It is obtained by

As the α-olefin having 5 or more carbon atoms, pentene-1
, 4-methylpentene-1, hexene-1, hebutene-
Examples include one or a combination of two or more of 1, octene-1, and α-olefins having 6 or more carbon atoms such as 4-methylpentene-1, hexene-1, and octene-1. The amount of alpha-olefin comonomer used must be such as to give an alpha-olefin content in the polymer chain per 1000 carbon atoms in the ranges stated above. In addition, the ultra-high molecular weight ethylene-α-olefin copolymer used is
It should have a molecular weight corresponding to the aforementioned intrinsic viscosity [η].

If the α-olefin content is less than 0.1 carbon atoms/1000 carbon atoms, a structure that is effective in improving creep resistance cannot be created;
When the number exceeds 5 carbon atoms/1000 carbon atoms, the degree of crystallinity decreases significantly, making it impossible to obtain a high elastic modulus.

In the present invention, the α-olefin component in the ultra-high molecular weight ethylene-α-olefin copolymer was determined using an infrared spectrophotometer (manufactured by JASCO Corporation). The absorbance of 1378 sub-1, which represents the bending vibration of the methyl group of the α-olefin incorporated into the diethylene chain, was measured, and from this, a calibration prepared using a model compound using a 130 nuclear magnetic resonance apparatus was performed. This is a value measured by converting the number of methyl branches per 1000 carbon atoms using a line.

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-α-olefin copolymer. As such a diluent, a solvent for the ultra-high molecular weight ethylene copolymer and various wax-like substances having compatibility with the ultra-high molecular weight ethylene copolymer are used.

The solvent preferably has a boiling point higher than the melting point of the copolymer, more preferably higher than the melting point +20°C.

Specific examples of such solvents include n-nonane, n-decane, n-undecane, n-dodecane, n-tetradecane, n-octadecane, liquid paraffin, aliphatic hydrocarbon solvents such as kerosene, xylene, and naphthalene. , aromatic hydrocarbon solvents such as tetralin, butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, pentylbenzene, dodecylbenzene, bicyclohexyl, decalin, methylnaphthalene, ethylnaphthalene, or their hydrogen dielectric compounds, 1,1, 2. Halogenated hydrocarbon solvents such as 2-tetrachloroethane, pentachloroethane, hexachloroethane, 1.2.3-trichloropronogne, dichlorobenzene, 1,2.4-)dichlorobenzene, bromobenzene, paraffin-based processes Examples include mineral oils such as oil, naphthenic process oil, and aromatic process oil.

As the waxes, aliphatic hydrocarbon compounds or derivatives thereof are used.

The aliphatic hydrocarbon compounds are mainly saturated aliphatic hydrocarbon compounds, and usually have a molecular weight of 2000 or less,
It is preferably 1000 or less, more preferably 800 or less, and is called a wax. These aliphatic hydrocarbon compounds include tocosan,
n-alkanes with 22 or more carbon atoms such as tricosane, tetracosane, triacontane, or mixtures of these with lower n-alkanes as main components, so-called paraffin wax separated and purified from petroleum, ethylene or ethylene and other α-olefins Polyethylene such as medium/low pressure polyethylene wax, high pressure polyethylene wax, ethylene copolymer wax, medium/low pressure polyethylene, high pressure polyethylene, etc., which is a low molecular weight polymer obtained by copolymerizing with Examples include waxes with reduced molecular weights, oxides of these waxes, oxidized waxes modified with maleic acid, and waxes modified with maleic acid.

As an aliphatic hydrocarbon compound derivative, for example, one or more, preferably 1 to 2, particularly preferably 1 force A/ is present at the end or inside of an aliphatic hydrocarbon group (alkyl group, alkenyl group). A compound having a functional group such as a xyl group, a hydroxyl group, a carbamoyl group, an ester group, a meltcapto group, or a cal-nyl group, with a carbon number of 8 or more, preferably a carbon number of 12 to 50, or a molecular weight of 130 to 2,000, preferably 200 to 800. fatty acids, aliphatic alcohols,
Fatty acid amides, fatty acid esters, aliphatic mercaptans,
Examples include aliphatic aldehydes and aliphatic ketones.

Specifically, the fatty acids include capric acid, lauric acid, myristic acid, pallic acid, stearic acid, and oleic acid; the fatty alcohols include lauryl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol; and the fatty acid amides include caprinamide and laurin. Examples of the amide, lumitinamide, stearylamide, and fatty acid ester include stearyl acetate.

The ratio of ultra-high molecular weight ethylene copolymer to diluent varies depending on the type, but generally speaking, it is 3:9.
7 to 80:20, especially 15:85 to 60:40
It is best to use a weight ratio of

When the amount of the diluent is lower than the above range, the melt viscosity becomes too high, making it difficult to perform melt intermixing and melt molding, and the surface of the molded product becomes extremely rough, easily causing stretching breakage and the like. On the other hand, if the amount of the diluent is larger than the above range, melt intermixing becomes difficult and the stretchability of the molded product becomes poor.

The bath melt kneading is generally preferably carried out at a temperature of 150 to 300°C, particularly 170 to 270°C; at temperatures lower than the above range, the melt viscosity becomes too high and melt molding becomes difficult; In some cases, the molecular weight of the ultra-high molecular weight ethylene copolymer decreases due to thermal degradation, making it difficult to obtain a molded article with high elastic modulus and high strength. The blending may be carried out by dry blending using a Henschel mixer, type 2 blender, etc., or by melt mixing using a single-screw or multi-screw extruder.

Melt molding is generally performed by melt extrusion. For example, filaments for drawing can be obtained by melt extrusion through a spinneret, and films, sheets or tapes for p1 drawing can be obtained by extrusion through a flat, to die or ring die, and further extrusion through a circular die. By doing this, stretch-blow molding/4' Ig() and Rison) are obtained. The present invention is particularly useful for producing drawn filaments, in which case the bath melt extruded from a spinneret may be subjected to drafting, ie, drawing in the molten state. The ratio of the extrusion speed [Vo] of the molten resin in the Gouy orifice to the winding speed Hv of the undrawn material cooled and solidified can be defined as a draft ratio by the following formula.

Draft ratio = V, /Vo ------- (2) This draft ratio depends on the temperature of the mixture, the molecular weight of the ultra-high molecular weight ethylene copolymer, etc., but can usually be 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, it is also possible to manufacture preforms for stretch blow molding by injection molding. The molded product can be cooled and solidified by forced cooling means such as air cooling or water cooling.

The unstretched molded product of the ultra-high molecular weight ethylene copolymer thus obtained is subjected to a stretching treatment. Of course, the degree of stretching treatment is such that molecular orientation in at least one axis direction is effectively imparted to the ultra-high molecular weight ethylene copolymer of the molded article.

It is desirable that the molded article of the ultra-high molecular weight ethyne copolymer be stretched at a temperature of generally 40 to 160°C, particularly 80 to 145°C. As a heat medium for heating and maintaining the unstretched molded body at the above-mentioned temperature, any of air, water vapor, and a liquid medium can be used.

However, as a heat medium, a solvent capable of eluting and removing the diluent mentioned above and whose boiling point is higher than the melting point of the molded body composition, specifically, decalin, decane, kerosene, etc., is used. Stretching is preferred because it makes it possible to remove the diluent mentioned above, eliminate stretching unevenness during stretching, and achieve a high stretching ratio.

Of course, the means for removing excess diluent from the ultra-high molecular weight ethylene copolymer is not limited to the above method, but may include a method of treating an unstretched material with a solvent such as hexane, hegetane, hot ethanol, chloroform, or benzene, and then stretching it; Excess diluent in the molded product can also be effectively removed by treating the stretched product with a solvent such as hexane, hebutane, hot ethanol, chloroform, benzene, etc. to obtain a stretched product with high elastic modulus and high strength. be able to.

The stretching operation can be performed in one stage or in multiple stages of two or more stages. The stretching ratio depends on the desired molecular orientation and the associated effect of increasing the melting temperature, but is generally between 5 and 8.
Satisfactory results can be obtained if the stretching operation is carried out at a stretching ratio of 0 times, especially 10 to 50 times.

In general, multistage stretching of two or more stages is advantageous; in the first stage, the stretching operation is carried out at a relatively low temperature of 80 to 120°C while extracting the diluent in the extruded product, and in the second and subsequent stages, the stretching operation is carried out at a relatively low temperature of 80 to 120°C. It is preferable to continue the stretching operation of the molded body at a temperature of 160 t: and at a temperature higher than the first-stage stretching temperature.

In the case of uniaxial stretching operations such as filament, tape, or uniaxial stretching, tension stretching can be performed between rollers with different peripheral speeds, and in the case of biaxially stretched films, longitudinal stretching can be performed between rollers with different peripheral speeds. In addition to carrying out tensile stretching in the direction, tensile stretching is also carried out in the transverse direction using a tenter or the like. Biaxial stretching by an inflation method is also possible. Furthermore, in the case of a three-dimensional molded article such as a container, a biaxially stretched molded article can be obtained by a combination of tensile stretching in the axial direction and expansion stretching in the circumferential direction.

The molecularly oriented molded product thus obtained can be heat-treated under restrictive conditions if desired. This heat treatment can generally be carried out at a temperature of 140 to 180°C, in particular 150 to 175°C, for 1 to 20 minutes, especially 3 to 10 minutes. By heat treatment, the crystallization of the oriented crystal part further progresses,
This results in a shift of the crystal melting temperature to a higher temperature side, an improvement in strength and elastic modulus, and an improvement in creep resistance at high temperatures.

As already mentioned, ultrahigh molecular weight ethylene-α according to the present invention
- The molecularly oriented molded article of the olefin copolymer is at least 20 degrees higher than the original crystal melting temperature ('rn1) of the copolymer.
At least one crystal melting peak (Tp
), and the heat of fusion based on this crystal melting peak (Tp) per total heat of fusion is 15 or more, preferably 2
It has the characteristic that it is 0% or more, especially 30% or more.

Ultra-high molecular weight ethylene copolymer original crystal melting temperature (Tm
) can be determined by a second run in a Mill differential scanning calorimeter by completely melting the molded body, cooling it to relax the molecular orientation in the molded body, and then raising the temperature again.

To explain further, in the molecularly oriented molded product of the present invention, there is no crystal melting peak at all in the above-mentioned crystal melting temperature range inherent to the co-mono-coalescence, or even if it exists, it exists only as a very slight tailing. . Crystal melting peak (T
p) generally within the temperature range Tm+20°C to Tm+50°C
In particular, it usually appears in the region of Tm+20°C to Tm+100'C, and this peak (Tp) often appears as several intersecting peaks within the above temperature range. That is,
This crystal melting peak (Tp) is within the temperature range Tm + 35°C
~Tm+100°C high temperature side melting scale peak (Tpt)
and a low-temperature melting peak (Tpt) in the temperature range Tm + 20°C to Tm + 35°C. Depending on the manufacturing conditions of the molecularly oriented molded product, TP
x and Tp! may further consist of multiple peaks.

These high crystal melting peaks (TpI - Tpt ) significantly improve the heat resistance of the molded product of the ultra-high molecular weight ethylene-α-olefin copolymer, and also improve the strength retention rate and elastic modulus retention after high-temperature thermal history. This is thought to contribute to the rate.

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

In addition, as long as the sum of the heat of fusion based on the high-temperature side melting peak (Tpt) satisfies the above-mentioned value, if the high-temperature side melting peak (Tps) does not stand out as a main peak, that is, a collection of small peaks. Even if the peak becomes large or broad, the heat resistance may be slightly lost, but the creep resistance is excellent.

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

The melting point was determined using a differential scanning calorimeter as follows.

Differential scanning calorimeter is DSCn type (manufactured by PerkinElmer)
was used. The sample is approximately 3 cm, 4 haze x 4 cm, thickness 0.2 w
It was restrained in the orientation direction by wrapping it around an aluminum plate of m. Next, the sample wrapped around an aluminum plate was encapsulated in an aluminum plate and used as a measurement sample.

In addition, the same aluminum plate used for the sample was sealed in the normally empty aluminum tube placed in the reference holder to maintain heat balance. First, the sample was held at 30°C for about 1 minute, and then the temperature was raised to 250°C at a temperature increase rate of 10°C/mln, and the melting point measurement at the first temperature increase was completed. Continued 25
Hold at 0 °C for 10 minutes, then 20 °C/mi
The temperature was lowered at a temperature lowering rate of n, and the sample was further held at 30°C for 10 minutes. Then, the second temperature increase was performed at 10℃/m 1
The temperature was increased to 250° C. at a temperature increase rate of n, and at this time, the melting point measurement was completed during the second temperature increase (second run). At this time, the maximum value of the melting peak was taken as the melting point. When it appears as a shoulder, a tangent is drawn between 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 is taken as the melting point.

Connect the points 60°C and 240°C of the endothermic curve and draw the straight line (
Draw a perpendicular line to a point 20°C higher than the original crystalline melting temperature (Tm) of the ultra-high molecular weight ethylene copolymer, which is determined as the main melting peak during the second temperature rise, and The part on the high temperature side is based on the crystal melting (Tm) inherent to the ultra-high molecular weight ethylene copolymer, and the part on the high temperature side is based on the crystal melting (Tp) that exhibits the function of the molded article of the present invention.
), and the heat of fusion of each crystal was calculated based on these areas. In addition, the heat of fusion based on the melting of Tpl and Tpl was determined by Tm+20 according to the above method.
The portion surrounded by the perpendicular line from 0.degree. C. and the perpendicular line from Tm+35.degree. C. was the heat of fusion based on the melting of Tp2, and the high temperature side portion was similarly calculated as the heat of fusion based on the melting of Tpt.

The degree of molecular orientation in a 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 ultra-high molecular weight ethylene copolymer of the present invention, for example, Yukichi Go, Teru Kubo: Industrial Chemistry Magazine Vol. 39, 992.
(1939), where H' is the half-width ('' )
It is.

The degree of orientation (F) defined by is 0.90 or more, especially 0.9
From the viewpoint of mechanical properties, it is desirable that the molecules be oriented so that the number of particles is 5 or more.

The drawn filament of the ultra-high molecular weight ethylene-α-olefin copolymer of the present invention has a strength retention rate of 95 degrees or more and an elastic modulus retention rate of 904 degrees or more after being subjected to a heat history of 5 minutes at 170°C. In particular, it has an excellent heat resistance of 95 inches or more, which is completely unrecognizable in conventional drawn polyethylene filaments.

In addition, this drawn filament has a resistance to leak f% under high temperature.
It has outstanding properties, with a breaking load of 30 inches,
The atmospheric temperature is 70°C, and the creep measured as elongation (chi) after 90 seconds is 7% or less, especially 5% or less, and the creep rate (i, 5ea) after 90 seconds to 180 seconds is 4 x 10 sec or less, especially 5 X 10 s
ec or less.

Furthermore, the molecularly oriented molded product of the ultra-high molecular weight ethylene-α-olefin copolymer of the present invention has excellent mechanical properties and is a plastic product.
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.

(Effects of the Invention) The molecularly oriented molded article of the ultra-high molecular weight ethylene-α-olefin copolymer of the present invention has an excellent combination of heat resistance, IJ-proofing properties, and mechanical properties. Thus, by utilizing this characteristic, the molecularly oriented molded product of the present invention is useful as a packaging material such as packing tape in addition to industrial textile materials such as high-strength multifilaments, strings, ropes, woven fabrics, and non-woven fabrics. It is.

In addition, a molded body in the form of a filament is made of niboxi resin,
It is clear that when used as reinforcing fibers for various resins such as unsaturated polyester and synthetic rubber, there is a significant improvement in heat resistance and cleaving resistance compared to conventional drawn ultra-high molecular weight polyethylene filaments. Dew. or,
This filament has high strength and low density, so it is different from conventional glass fiber, carbon fiber, etc. It is particularly effective because it can be made lighter compared to molded products using lon fibers, aromatic polyamide fibers, aromatic polyimide fibers, etc. Similar to composite materials using glass fiber etc., UD (Unit D
ir@ctional) laminate, SMC (Sheet
Molding Compound), BMC (Bu
It is possible to perform molding processing such as lk Molding Compound), automobile parts, etc. - It is expected that the composite material will be used in various lightweight, high-strength fields such as structures for boats and yachts, and substrates for electronic circuits.

Example 1 Polymerization of ultra-high molecular weight ethylene-4-methylpentene-1 copolymer> Slurry polymerization of ethylene was carried out using a Ziegler catalyst and n-decane 11 as a polymerization solvent. At this time,
Polymerization was started by initially adding 25 d of 4-methyl-4-tene-1 as a comonomer and 3 ONm of hydrogen to adjust the molecular weight. The pressure of the reactor is 5kg1 for ethylene gas.
The polymerization was completed in 1.5 hours at 70°C by continuously supplying the polymer to maintain a constant pressure of 5+".The obtained ultra-high molecular weight ethylene-
The yield of 4-methylpentene-1 copolymer powder is 2641
The intrinsic viscosity [η] (decalin, 135°C) is 9.66d.
f#.

The content of 4-methylinthene-1 determined by infrared spectrophotometer is 1
000 carbon atoms per vl, 7 pieces.

Preparation of stretched oriented product of ultra-high molecular weight ethylene-4-methylinten-1 copolymer> The above-mentioned ultra-high molecular weight ethylene-4-methylinten-1 copolymer and Nokurafinwa, Kusu (melting point = 69°C, molecular weight = 490 ) with 20:80. The weight ratio mixture was melt spun under the following conditions. 0.1 part by weight of 3,5-dimethyl-tert-butyl-4-hydroxytoluene was added to the mixture as a process stabilizer based on the ultra-high molecular weight ethylene-4-methylpentene-1 copolymer. Next, the mixture was extruded using a single screw extruder (screw diameter = 25 mm).

L/D=25. Thermoplastic Kogyo Co., Ltd.) was used to melt-knead the mixture at a set temperature of 190° C., and then the melt was melt-spun using a spinning die with an orifice diameter of 2 mm attached to an extruder. The spun fibers were taken with an air gap of 1801 at a draft ratio of 36 times, and were cooled and solidified in air to obtain undrawn fibers. Further, the undrawn yarn was drawn under the following conditions to obtain oriented fibers. Two-stage stretching was performed using a Godetstrol from Ohdai. At this time, the heating medium in the -th drawing tank is n-
The heating medium in the second drawing tank was triethylene glycol and the temperature was 145°C. The effective length of each tank was 50 mm.

During stretching, the rotational speed of the 1-i'' putter roll was set to 0.
．． Fibers with the desired draw ratio were obtained by changing the rotational speed of the third godet roll as 5 m/ml n.

2nd: The rotational speed of the 2'' trolley was appropriately selected within the range that allowed stable stretching. Most of the initially mixed/graft-in wax was extracted in the n-f can tank during stretching.

The stretching ratio was determined by calculation from the rotational speed ratio of the first Godetrol and the third Godetrol.

Measurement of tensile properties> The elastic modulus and tensile strength were measured at room temperature (23° C.) using a DO8-50M tensile tester manufactured by Shimadzu Corporation. At this time, the sample length between the flanges was 100 m+ and the tensile speed was 100.
It was w/min. The elastic modulus was calculated using the slope of the tangent at the initial elastic modulus. The fiber cross-sectional area required for calculation is calculated by setting the density to 0.
．． It was calculated from the weight as 9617cc.

Measurement of creep resistance characteristics〉 The creep test was performed using a thermal stress strain measuring device TMA/8810 (
Sample length is 1c! n
The test was carried out under accelerated conditions at an ambient temperature of 70° C. and a weight equivalent to 30 times the breaking load at room temperature. IJ-7
In order to quantitatively evaluate 't, the following two values were obtained.

First, CR the stretch after 90 seconds. , and from 90 seconds to 180
The average cleave speed (see'') after seconds was taken as the nose.

<Tensile modulus and strength retention after heat history> The heat history test was conducted by leaving the material in a gear oven (manufactured by -4-Fect Open Nitabai Seisakusho).

The sample had a length of about 3F+1, and a plurality of pulleys were installed at both ends of a stainless steel piece, and both ends of the sample were fixed by folding it back over the other end. At this time, both ends of the sample were fixed to such an extent that the sample did not sag, and no tension was actively applied to the sample. The tensile properties after the thermal history were measured based on the description of the measurement of tensile properties described above.

Table 1 shows the tensile properties of the stretched oriented fibers.

Table 1 Sample-17,9252,0646,75,26 Sample-1
The first endothermic characteristic curve measured by the differential scanning calorimeter is
Furthermore, the endothermic characteristic curve of the second run (second run) is shown in FIG. The original crystal melting peak of sample-1 is 12
At 9.2°C, the ratios of Tp and TPt to the total crystal melting peak area of Sample-1 were 57.1%, respectively.
It was 13.3%. Creep resistance is CReo = 4
．． 9% g = 3.33 x 10 s·C. The creep characteristics of Sample-1 are shown in FIG. In addition, the elastic modulus retention after heat history at 170°C for 5 minutes is Fi11.
The 2.8% strength retention rate was 97.1%, and although a slight decrease in strength retention rate was observed due to thermal history, the elastic modulus was on the contrary improved.

Example 2 <Polymerization of a polymer i ethylene/4-methylpentene-1 copolymer> A slurry polymerization of ethylene was carried out using a Ziegler catalyst and n-deca 7Lt as a polymerization solvent.

At this time, 4-methylpentene-150 as a comonomer
In order to adjust the molecular weight, 5ONd of hydrogen was added all at once before starting the polymerization, and then the polymerization was started.

Ethylene gas was continuously supplied to the reactor to maintain a constant pressure of 5'Kji/cm2, and the polymerization was completed at 70° C. in 1.5 hours. The yield of the ultra-high molecular weight ethylene-4-methylinthene-1 copolymer powder was 172 g, and the intrinsic viscosity [η] (decalin, 135°C) was 10.55 di/
g. The content of 4-methylpentene-1 comonomer measured by infrared spectrophotometer was 9062 out of 1000 carbon atoms.

<Preparation and physical properties of ultra-high molecular weight ethylene/4-methylpentene-1 copolymer drawn and oriented product> A drawn and oriented fiber was prepared by the method described in Example 1. The tensile properties of the obtained drawn and oriented fibers are shown in Table 2.

Table 2 Sample-214, 6162, 1953, 64, 5 Sample-2
The first endothermic characteristic curve measured by the differential scanning calorimeter is the sixth
In addition, the endothermic characteristic curve of the second run (second run) is shown in FIG. The original crystal melting peak of sample-2 is 13
At 1.3°C, the proportions of Tp and Tpl in the total crystal melting peak area of Sample-2 were 93.13% and 3.8%, respectively.

Creep resistance is CReo = 2.46%, iMi1.
It was 21XIQ-5sec.

The creep characteristics of Sample-2 are shown in FIG. 170 again
℃, the elastic modulus retention rate after 5 minutes of thermal history is 108.3%,
The strength retention rate was 96.3 cm, and although there was a slight decrease in the strength retention rate, on the contrary, the elastic modulus improved.

Example 3 Polymerization of ultra-high molecular weight ethylene/hexene-1 copolymer> Slurry polymerization of ethylene was carried out using a Ziegler catalyst and n-j can 11 as a polymerization solvent.

At this time, 25 mJ of hexene 1t'' and 4ONm of water to adjust the molecular weight were added at once as a comonomer before starting the polymerization. Ethylene gas was added to the reactor at a pressure of 5.
The polymerization was completed in 1.5 hours at 70° C. by continuously supplying so as to maintain a constant pressure of 7 cm 2 kg. The yield of the obtained ultra-high molecular weight ethylene/hexene-1 copolymer powder was 231.9
, the intrinsic viscosity [η] (decalin, 135°C) is g, 3
7 dl! /I% hexerin by infrared spectrophotometer
The monomer content was 2.3 per 1000 carbon atoms.

Preparation of a drawn and oriented ultra-high molecular weight ethylene/hexene-1 copolymer and its physical properties> A drawn and oriented fiber was prepared by the method described in Example 1. Table 3 shows the tensile properties of the obtained drawn and oriented fibers.

Sample-313, 7141, 8942, 45, 21 sample-
The endothermic characteristic curve of the first run measured by the differential scanning calorimeter of No. 3 is shown in FIG. 8, and the endothermic characteristic curve of the second run (second run) is shown in FIG. The original crystal melting peak of sample-3 is 1
At 29.1°C, the ratio of Tp and TTlt to the total crystal melting peak area of sample-3 was 89.1, respectively.
% and 16chi.

The creep resistance of sample-3 is CRoe = 2.55 chi,
! = 1.21X10 sec. Sample-3
Figure 15 shows the creep characteristics of . In addition, the elastic modulus retention rate after 5 minutes of thermal history at 170°C was 102. (1. Strength retention rate was 99.5.

Example 4 Polymerization of ultra-high molecular weight ethylene/octene-1 copolymer> Using a Ziegler catalyst, n-decane II! Next, slurry polymerization of ethylene was carried out using as the polymerization solvent.

At this time, 125 ml of octene-1 as a comonomer and 4 ON ml of hydrogen for molecular weight adjustment were added all at once before starting the polymerization to start the polymerization. Ethylene gas was continuously supplied to the reactor so as to maintain a constant pressure of 5 kg 7 cm, and the polymerization was completed at 70° C. in 2 hours. The yield of the obtained ultra-high molecular weight ethylene/octene-1 copolymer powder was 178I, and its intrinsic viscosity [η] (decalin, 135°C) was 10.666.
i/9, and the octene-1 comonomer content by infrared spectrophotometer was 0.5 out of 1000 carbon atoms.

Preparation of drawn and oriented ultra-high molecular weight ethylene/octene-1 copolymer and its physical properties> A drawn and oriented fiber was prepared by the method described in Example 1. Table 4 shows the tensile properties of the obtained drawn and oriented fibers.

Table 4 samples - 411, 1162, 1865, 73, 68 samples -
The endothermic characteristic curve of the first run measured by the differential scanning calorimeter No. 4 is shown in FIG. 10, and the endothermic characteristic curve of the second run (second run) is shown in FIG. The original crystal melting peak of Sample-4 was 132°C, and the ratios of Tp and Tpt to the total crystal melting peak area of Sample-4 were 97.7% and 5.0%, respectively. The creep resistance of sample-4 is CH
2O = 2.01 chi, ε = 9.52 x 10 s
ec te;hfc. Sample-4 glue! All J7' characteristics are shown in FIG. In addition, the elastic modulus retention rate after heat history at 170°C for 5 minutes was 109.2%, and the strength retention rate was 101.9%, indicating that both elastic modulus and strength improved with heat history.

Comparative Example 1 Ultra-high molecular weight polyethylene (homopolymer) powder (intrinsic viscosity Cyy) = 7.42 di/I, Decalin.

135°C) = 20 parts by weight and paraffin wax (melting point;
69°C, molecular weight = 490): 80 parts by weight of the mixture was melt-spun and drawn by the method of Example 1 to obtain draw-oriented fibers.

Table 5 shows the tensile properties of the obtained drawn and oriented fibers.

Table 5 Sample-59, 3252, 5371, 54, 31 The endothermic characteristic curve of Ultra High Polymer i Polyethylene Stretched Oriented Fiber Sample-5 at the first temperature increase measured by a differential scanning calorimeter is shown in FIG.
Furthermore, the endothermic characteristic curve during the second temperature increase (second run) is shown in FIG.

The original crystal melting peak of ultra-high molecular weight polyethylene sample-5 is 135. Tp relative to IC1 total crystal melting peak area
The ratio of υ was 8.8chi.

Similarly, the ratio of the high temperature side peak TpI to the total crystal melting peak area is 1. It was Om. Another 170
After a heat history of 5 minutes at ℃, the retention of elastic modulus was 80.4% and the retention of strength was 79.2%, and both the elastic modulus and strength decreased due to the heat history. Creep resistance is CR,, = 12.
01, t = 1.07 x 10-58ec-'. The creep characteristics of Sample-5 are shown in FIG.

Comparative Example 2 Ultra-high molecular weight polyethylene (homopolymer) powder (intrinsic viscosity [η:l = 10.2 di/g. Decalin.

A mixture of 20 parts by weight (135°C) and 80 parts by weight of rough-in wax (melting point = 69°C, molecular weight = 490) was melt-spun and drawn by the method described in Example 1 to obtain drawn and oriented fibers. . Table 6 shows the tensile properties of the obtained tele-stretched oriented fibers.

Table 6 Samples Fineness Stretching ratio Strength Elastic modulus Elongation denier times GPa GPa Sample-66, 0253, 1878, 25, 78 Ultra-high molecular weight polyethylene stretch oriented fiber sample-6 1st measurement by differential scanning calorimeter The endothermic characteristic curve during temperature rise is shown in Figure 13.
Furthermore, the endothermic characteristic curve during the second temperature increase (second run) is shown in FIG.

The original crystal melting peak of ultra-high molecular weight polyethylene fiber sample-6 was 135.5°C, and the ratios of Tp and Tpl to the total crystal melting peak area were 13.8% and 1.1%, respectively. The creep resistance of sample-6 is CR
Meeting ◎=8.2%, ;=4. It was t7xto-'5ee-'. FIG. 15 shows the cre-7'% property of Sample-6.

Furthermore, the elastic modulus retention after 5 minutes of heat history at 170°C was 86.
, 1%, the strength retention rate was 93.1 cm, and the elastic modulus in particular decreased significantly.

[Brief explanation of drawings]

Figure 1 shows the endothermic characteristic curve of the ultra-high molecular weight ethylene/4-methylinter-1 copolymer powder used in Example 1, measured by a differential scanning calorimeter. Figure 2 shows the ultra-high molecular weight ethylene obtained in Example 1.・4-
The endothermic characteristic curve of the methylpentene-1 copolymer stretched oriented fiber measured by a differential scanning calorimeter in a restrained state. Figure 3 shows the endothermic characteristic curve measured by a differential scanning calorimeter of the ultra-polymer t-1e') ethylene powder used in Comparative Example 1. Figure 4 shows the endothermic characteristic curve of the drawn and oriented ultra-high molecular weight polyethylene fiber obtained in Comparative Example 1 measured by a differential scanning calorimeter in a restrained state. The endothermic characteristic curve when subjected to temperature measurement (second run), Figure 6 shows the ultra-high molecular weight ethylene/4-methylpentene-1 obtained in Example 2.
The endothermic characteristic curve measured by differential scanning calorimetry of the copolymer drawn and oriented fiber in a restrained state, Figure 7 shows the endothermic characteristic curve when the sample in Figure 6 was subjected to the second temperature increase measurement, W, and Figure 8 shows The endothermic characteristic curve measured by a differential scanning calorimeter in a restrained state of the ultra-high molecular weight ethylene/hexene-1 copolymer stretched oriented fiber obtained in Example 3. Figure 9 shows the second heating of the sample in Figure 8. Figure 10 shows the endothermic characteristic curve obtained in Example 4, measured by a differential scanning calorimeter, of the nine ultra-high molecular weight ethylene octene-1 copolymer stretched and oriented fibers in a restrained state. Figure 11 shows the endothermic characteristic curve when the sample in Figure 10 is subjected to the second heating measurement. Figure 12 is the endothermic characteristic curve when the sample in Figure 4 is subjected to the second heating measurement. Figure 13 shows the endothermic characteristic curve of the ultra-high molecular weight polyethylene stretched oriented fiber obtained in Comparative Example 2 measured by a differential scanning calorimeter in a restrained state. Figure 14 shows the sample shown in Figure 13 subjected to a second heating measurement. The endothermic characteristic curve and FIG. 15 are for Example 1. Example 2. Example 3. Example 4.
The creep characteristic curves of the drawn and oriented fibers of each polymer obtained in Comparative Example 1 and Comparative Example 2 are shown in full. Procedural proceedings (spontaneous) June 20, 1988 Director General of the Japan Patent Office Yoshi 1) Takeshi Moon 1, Indication of the case 1988 Patent Application No. 109724 2, Title of the invention 3, Person making the amendment and the case Relationship Patent applicant address 3-2-5 Kasumigaseki, Chiyoda-ku, Tokyo Name (5
88) Mitsui Petrochemical Industries Co., Ltd. 4, Agent 〒105 6. Detailed explanation of the invention in the specification subject to amendment, column for brief explanation of drawings and drawing 7, Contents of amendment ■9 Detailed explanation of the invention ( 1) Add the following sentence between line 7 and line 8 on page 29 of the specification. r Ethylene-α-olefin (Cs or more) according to the present invention
Copolymer fibers have a characteristic that when a load slightly smaller than the breaking load is applied at room temperature, it takes a significantly long time to break. That is, these fibers have a strength of 750 to 1500 MP at room temperature.
Breaking time (T, ho) when applying a load (F) of a
ur) has the characteristic that . For ultra-high molecular weight homopolyethylene fibers and ethylene-propylene copolymer fibers, this breaking time (T) is considerably shorter than that for the above-mentioned fibers. Measurement of creep rupture time> Creep rupture time was determined as follows. Sample summary 1
Provide a distance between the gauge lines of 100 cm at equal intervals from the center of the 50 cm sample, and insert the gauge lines. A desired load is applied to the sample under conditions of an ambient temperature of 23° C. and a relative humidity of 55%. The elapsed time from immediately after application to rupture is measured and taken as the creep rupture time. Excluding the 6 cases that fractured outside the marked line, one measurement of the minimum failure time in the 6 measurements was taken as the surplus V, and the average creep rupture time of the 5 measurements was taken as the measurement value. 1 (2) Add the following sentence between the second and third lines of page 41. r Table 5 shows the relationship between the applied load and the creep rupture time for Sample-4. The relationship between the applied load in Table 5 and the creep rupture time is shown in FIG. (3) ``Table 5'' in lines 9 and 111 on page 41 is corrected to ``Table 6'' in Table 6. (4) 2nd line from the bottom on page 42 and 1st line on page 43:
"Table 6" is corrected to "Table 7 1. (5) Add the following sentence between the second and third lines from the bottom of page 43. r Applied load and creep of sample-6 The relationship between the fracture time and the fracture time is shown in Table 8. The relationship between the applied load in Table 8 and the fracture time at room temperature is shown in Figure 16 together with sample-4. 1 ++ , Brief explanation of the drawing ( 1) Add the following sentence under the last line of page 45 of the specification: r Figure 16 is a diagram showing the relationship between applied load and failure time at room temperature for each fiber. 1 1II, Drawing (1) Add Figure 16 as attached.

Claims (3)

[Claims] (1) Ultra-high molecular weight ethylene having an intrinsic viscosity [η] of at least 5 dl/g and an average content of α-olefins having 5 or more carbon atoms from 0.1 to 15 per 1000 carbon atoms.
A molecularly oriented molded product of an α-olefin copolymer, the molded product has at least two crystal melting endothermic peaks when measured with a differential scanning calorimeter in a restrained state, and has a main peak during the second heating. It has at least one crystal melting endothermic peak (Tp) at a temperature that is at least 20°C higher than the original crystal melting temperature (Tm) of the ultra-high molecular weight ethylene-α-olefin copolymer, which is determined as a melting endothermic peak, and is completely melted. A molecularly oriented molded article characterized in that the amount of heat based on this crystal melting endothermic peak (Tp) per amount of heat is 15% or more. (2) The molecularly oriented molded article according to claim 1, wherein the α-olefin has 6 or more carbon atoms. (3) The molecularly oriented molded article according to claim 1, wherein the content of α-olefins is on average 0.5 to 10 per 1000 carbon atoms.