JPH04185709A - Molecularly oriented molded body of high-molecular weight polyethylene - Google Patents

Abstract

PURPOSE:To obtain the subject molecularly oriented molded body, composed of high-molecular weight polyethylene, having a prescribed relation among tensile strength, weight-average molecular weight and size and excellent in strength with hardly any deterioration in tensile strength even when subjected to corona discharge treatment. CONSTITUTION:A molecularly oriented molded body is composed of a molecularly oriented molded body of high-molecular weight polyethylene having 300000-600000 weight-average molecular weight. The aforementioned molded body has <=15 denier size and >=1.7 GPa tensile strength. The tensile strength [S (GPa)], the weight-average molecular weight [M (g/mol)] and the size [D (denier)] thereof satisfy the relation expressed by the formula.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molecularly oriented molded article of high molecular weight polyethylene.

Technical Background of the Invention Conventionally, when producing polyethylene fibers having an excellent tensile strength of 1.7 GPa or more, ultra-high molecular weight polyethylene with a molecular weight of about 1.000.000 or more was used as the raw material. This is mainly because it is theoretically thought that the ends of molecules in the fiber structure become structural defects that reduce tensile properties, especially tensile strength.The higher the molecular weight, the higher the strength of the fiber. This is because it was thought that they could be obtained. For example, JP-A-63
-6631, No. 6 discloses a method for obtaining gel filaments from a dilute solution of ultra-high molecular weight polyethylene having a molecular weight of 600,000 or more, and then drawing the filaments to obtain filaments with excellent tensile properties. There is. In this publication, specifically, ultra-high molecular weight polyethylene, which has a molecular weight of as much as 1.500.000, is used as a raw material.

However, as the molecular weight of polyethylene increases, its moldability decreases. For example, when attempting to produce a filament with excellent tensile properties by the method described in JP-A No. 63-6631.6, the higher the molecular weight, the lower the solubility in the solvent, or the lower the solubility in the solvent. The viscosity of the solution becomes high at a concentration of 50%, and filament breakage is more likely to occur during the spinning or drawing process. Therefore, in order to prevent this from happening, when polyethylene with extremely high molecular weight is used, it is necessary to lower the concentration of the solution or to slow down the spinning speed and drawing speed to some extent. As described above, when the molecular weight of the raw material polyethylene increases, it is possible to obtain fibers with excellent tensile properties, but on the other hand, the moldability deteriorates, which inevitably leads to a decrease in industrial productivity.

In addition, ultra-high molecular weight polyethylene, which has a very high molecular weight,
Heat deterioration is likely to occur during molding. Therefore, when preparing raw materials,
Alternatively, a certain degree of molecular weight reduction is unavoidable during spinning, and carbonyl groups etc. are generated due to thermal deterioration.
It is thought that this will have an adverse effect on the weather resistance of the polyethylene fibers obtained.

By the way, the main use of polyethylene fibers having high strength is woven fabrics. Specifically, such woven fabrics are used for reinforcing fibers, bulletproof fabrics, cut protection clothing, etc., or when used for composite reinforcing fibers, the weave density, adhesiveness, etc. From this point of view, it is hoped that thinner polyethylene fibers will emerge, and when used in bulletproof fabrics and cut protection clothing, it is desirable to have thinner polyethylene fibers that have excellent strength from the standpoints of ballistic retention and cut resistance. He is 1 year old,
In addition, from the viewpoint of sensory experience, it is desired that fibers with excellent texture and fineness be produced.

By the way, it has conventionally been thought that in order to obtain polyethylene fibers having high strength, it is necessary to use ultra-high molecular weight polyethylene having a molecular weight of at least 600,000 or more as a raw material, as described above.

For example, JP-A-59-187614 discloses a method for manufacturing polyethylene fibers, and the polyethylene fibers with the highest strength obtained in the examples of the publication have a fiber diameter of 4.2 denier. It is 3.16GPa. In order to obtain such polyethylene fibers, high molecular weight polyethylene with an intrinsic viscosity of 820 dA/''g is used;
Its molecular weight, calculated from its intrinsic viscosity, is approximately 750,000.

Therefore, according to the conventional wisdom that the strength of polyethylene fiber is proportional to the molecular weight of the polyethylene used as a raw material, from high molecular weight polyethylene with a weight average molecular weight of 600,000 or less, 3.1
It is considered that it is only possible to obtain fibers with a strength of 6 GPa or more.

By the way, oriented polymer polyethylene molecules are sometimes used as fibers for reinforcing composite materials, and it is desired that such fibers for reinforcing composite materials have excellent adhesiveness between the fibers and the matrix. However, since polyethylene generally does not have very good adhesive properties, measures have been taken to improve the adhesive properties, and one known method is corona discharge treatment.

When conventionally known oriented high molecular weight polyethylene molecules are subjected to corona discharge treatment, the adhesion may be improved or the tensile strength may be significantly reduced.

The inventors of the present invention conducted extensive research to break through the common sense as described above, and found that even if the material is made of high molecular weight polyethylene with excellent moldability and a weight average molecular weight of 600,000 or less, the fineness (denier) can be reduced. The inventors have discovered that, by doing so, it is possible to obtain thin polyethylene fibers, that is, polyethylene molecularly oriented molded products, which have excellent strength and whose tensile strength is significantly reduced even when subjected to corona discharge treatment, and have completed the present invention. .

Purpose of the Invention The present invention has been made in view of the above-mentioned points, and has been made to provide a molecularly oriented material which has excellent formability when producing it, and whose tensile strength does not drop significantly even when subjected to corona discharge treatment. figure,
It is an object of the present invention to provide a high molecular weight polyethylene molecular oriented material, such as a high molecular weight polyethylene fiber, which also has excellent strength.

Summary of the Invention The high molecular weight polyethylene molecularly oriented molded article according to the present invention includes:
A polymer oriented molded article made of high molecular weight polyethylene having a weight average molecular weight of 300.000 to 600.00G, having a fineness of 15 deniers or less, and a tensile strength of at least 1, 7 GPa or more, and its tensile strength Strength S (GPa) and its weight average molecular weight M (g/”
mol ) and its fineness (denier) are within a range that satisfies the relationship expressed by 300,000 + 0.000.

DETAILED DESCRIPTION OF THE INVENTION The high molecular weight polyethylene molecularly oriented molded article according to the present invention will be specifically described below.

Raw material polyethylene The molecularly oriented molded article obtained by the present invention has a weight average molecular weight of 300.000 to 600.000. OO[1, preferably 3
50,000 to 60 [1,000, more preferably
400. [lO0~6G0. %a from high molecular weight polyethylene that is OOC. The weight-average needle -i'' height of high molecular weight polyethylene can be determined by calculation from the intrinsic viscosity measured in a decalin solution at 135°C.

The average molecular weight of the polymer 1 polyethylene used in the present invention is preferably less than 60 Ti J: J from the viewpoint of stretch formability, and less than 300,000 l, 5
It is difficult to obtain a molecularly oriented polymeric polyethylene molded product having a strength of GPa or higher, and the resulting molecularly oriented molded product tends to have inferior performance such as creep resistance or abrasion resistance. Note that Ct+anig is Journal
cl Polyme+ S [i+p
According to the formula reported in [etvoi36.91 (1959)], the intrinsic viscosity of high molecular weight polyethylene having a molecular weight of 300,000 to 600,000 is in the range of 4.23 to 6.87.

The high molecular weight polyethylene used in the present invention may be a homopolymer of ethylene or a copolymer of ethylene and a small amount of a-olefin. When such a copolymer of ethylene and α-olefin is used, the ethylene content is usually 95 mol% or more, preferably 98 mol% or more.

Such a-olefins usually have 3 carbon atoms.
~10 α-olefins are used.

Specifically, such α-olefins include propylene, 1-butene, 3-methyl-1-buteno, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1
-Heptene, 1-octene, etc. are used. In addition to the above α-olefin, other copolymerization components such as cyclic olefins may be copolymerized within a range that does not impair the properties of ethylene used in the present invention.

Molecularly oriented molded product The high molecular weight polyethylene molecularly oriented molded product according to the present invention includes:
Made of high molecular weight polyethylene with a weight average molecular weight of 3H,H[l to 6H,on, fineness of 15 denier or less,
It is preferably 12 denier or less, more preferably 10 denier or less, and has a tensile strength of at least 1.7 G.
Pa or more, preferably 1.8 GPa or more, more preferably 2.0 GPa or more, and its tensile strength is 5 (
GPa) and its weight average molecular weight M (g/mol)
And its fineness (denier), formula [1]% formula% (1
It satisfies the relationship shown by 00 [1].

The high molecular weight polyethylene molecularly oriented molded article according to the present invention is
It is desirable to have excellent tensile strength and tensile modulus, and the tensile modulus is preferably 20 GPa or more, preferably 40 GPa or more.

The degree of molecular orientation in the above-mentioned high molecular weight polyethylene molecularly oriented molded product can be determined by X-ray diffraction, birefringence, polarized fluorescence, and the like. The molecularly oriented molded article according to the present invention has a degree of orientation according to the half-width, which is described in detail in, for example, Yukichi Go and Terubu Kubo, Chemical Engineering Journal, Vol. 39, p. 992 (1939), that is, the degree of orientation according to the formula 90 -H/2 Orientation degree F-□ 90° (Here, H is the half-width (') of the intensity distribution curve along the Debye ring of the strongest paratope plane on the equator line.) It is desirable that the molecular orientation is 0.98 or more, particularly 0.99 or more.

Next, a method for manufacturing a high molecular weight polyethylene molecularly oriented molded article according to the present invention will be explained.

In the present invention, in order to mold the molecularly oriented molded article, the above-described high molecular weight polyethylene and a diluent are mixed and kneaded.

As such a diluent, a solvent for high molecular weight polyethylene or various wax-like substances having dispersibility for high molecular weight polyethylene may be used.

The solvent used is one having a boiling point higher than the melting point of the high molecular weight polyethylene, more preferably higher than the melting point +20°C.

Specifically, such solvents include F-nonane, n
-decane, n-undecane, n-todecano, r)-tetradecane, n-octadecane or liquid graphite, aliphatic hydrocarbon solvents such as kerosene, quinolene, naphthalene, tetralin, butylhensen, p-cymene, cyclohexylbenzene , siethylhensen, hentylbenzene, dodecylhensen, bicyclohexyl, decalin,
Aromatic hydrocarbon solvents such as methylnaphthalene and ethylnaphthalene or their hydrogenated derivatives, 1°1.22-tetrachloroethane, pentachloroethane, hexachloroethane, 1.2.341J chloropropane, dichlorobenzene, 1.2.4- Halogenated hydrocarbon solvents such as dichlorobenzene and promohenzene, mineral oils such as paraffinic process oils, naphthenic process oils, and aromatic process oils are used.

As the wax-like substance, one that is liquid at room temperature can be used, but it is preferable to use one with a melting point of 25° C. or higher. By using such a wax-like substance that is solid at room temperature as a diluent, the wax-like substance solidifies and tightens immediately after being extruded from the tie nozzle, causing the orientation state of the high molecular weight polyethylene oriented within the stick to collapse. As a result, the molecular orientation tends to remain as history in the obtained polyethylene molded product, so that a polyethylene molded product having a good degree of orientation can be obtained.

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

As the aliphatic hydrocarbon compound, a paraffin wax which is mainly composed of a saturated aliphatic hydrocarbon compound and has a molecular weight of usually 2,000 or less, preferably 1,000 or less, more preferably 800 or less is used. Specifically, these aliphatic hydrocarbon compounds include n-alkanes having 22 or more carbon atoms such as tocosan, tricosane, tetracosane, and triacontane, mixtures of these with lower n-alkanes as main components, and separation and refinement from petroleum. paraffin wax, medium/low pressure polyethylene wax which is a low molecular weight polymer obtained by copolymerizing ethylene or ethylene with other a-olefins, high pressure polyethylene wax, ethylene copolymer wax, or medium/low pressure polyethylene. , waxes obtained by reducing the molecular weight of polyethylene such as high-pressure polyethylene by thermal degradation, oxides of these waxes, oxidized waxes modified with maleic acid, waxes modified with maleic acid, and the like are used.

Examples of aliphatic hydrocarbon compound derivatives include one or more, preferably one to two, particularly preferably one, carboxyl group or hydroxyl group at the terminal or inside of an aliphatic hydrocarbon group (alkyl group or alkenyl group). , a compound having a functional group such as a carbamoyl group, an ester group, a mercapto group, or a carbonyl group, with a carbon number of 8 or more, preferably a carbon number of 12 to 50, or a molecular weight of 130 to 2000,
Preferably, 200 to 800 fatty acids, aliphatic alcohols, fatty acid amides, fatty acid esters, aliphatic mercaptans, aliphatic aldehydes, aliphatic ketones, etc. are used.

Specifically, fatty acids include capric acid, lauric acid,
Myristic acid, palmitic acid, stearic acid, oleic acid, etc. are used, the aliphatic alcohols used include lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, etc., and the fatty acid amides include caprinamide, lauramide, palmitinamide, Stearylamide is used, and fatty acid esters such as stearyl acetate are used.

The mixing ratio (weight ratio) of polyethylene and diluent varies depending on the type, but - 3.9 when fishing on a boat.
It is desirable that the ratio is 7 to 8020, preferably 15:85 to 60:40. If the amount of the diluent is lower than the above range, the melt viscosity will become too high, making melt kneading and melt molding difficult, and the molded product will have a markedly rough surface and tends to be prone to stretch breakage. On the other hand, if the amount of the diluent is larger than the above range, melt-kneading becomes difficult, and the molded product tends to have poor stretchability.

It is desirable that the above-mentioned melt-kneading is generally carried out at a temperature of 150 to 300°C, preferably 170 to 2706°C; at temperatures lower than the above range, the melt viscosity tends to be too high, making melt molding difficult. If the molecular weight of the ultra-high molecular weight ethylene polymer is higher than the above range, the molecular weight of the ultra-high molecular weight ethylene polymer tends to decrease due to thermal degradation, making it difficult to obtain a molded article with a high elastic modulus and high strength. The above melt-kneading may be carried out by dry blending using a Henschel mixer, N' type blender, etc., or may be carried out using a single-screw or multi-screw extruder.

An unstretched high molecular weight polyethylene molded article is obtained by extruding a kneaded mixture of high molecular weight polyethylene and a diluent as described above through a spinneret.

At this time, in order to obtain a molded product with excellent strength, the shear stress of the high molecular weight polyethylene during spinning should be set to 1.0×105
dyr1/'aLI~8X1.05dya icr! Preferably, it is 2 x 105 dVn/cIr1 to 8 x 105 dVn/d. It is also possible to apply a draft to the spun molten material, that is, to draw it in the molten state. The draft ratio can be defined as the ratio of the extrusion speed (■0) of the molten resin in the die orifice and the winding speed (2) of the undrawn material cooled and solidified.

Draft ratio = V/V.

Such a draft ratio depends on the temperature of the mixture, the molecular weight of polyethylene, etc., but is usually 3 or more, preferably 6.
It is desirable to set the above.

In addition, the mixture of high molecular weight polyethylene and diluent is not limited to extrusion molding, and in the production of various stretch molded containers, etc., preforms for stretch blow molding can also be manufactured by injection molding. be. The obtained molded product can be cooled and solidified by forced cooling means such as air cooling or water cooling.

Next, the thus obtained unstretched molded article of high molecular weight polyethylene is subjected to stretching treatment to obtain a molecularly oriented molded article of high molecular weight polyethylene.

The stretching of the polyethylene molded body is generally carried out at 40 to 160°C,
In particular, it is desirable to carry out at a temperature of 80 to 145°C. As a heat medium for heating and maintaining the unstretched molded body at the above temperature, air, steam, or a liquid medium can be used. However, as a heat medium, a solvent that can elute and remove 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. It is preferable to carry out the stretching operation, since it becomes possible to remove the diluent described above, eliminate stretching unevenness during stretching, and achieve a high stretching ratio.

Of course, the means to remove diluent from polyethylene is
Limited to the above method, the unstretched material may be treated with l\xane, heptane,
It can also be carried out by a method of treating with a solvent such as hot ethanol, chloroform or benzene and then stretching, or by a method of treating the stretched product with a solvent such as hexane, heptane, hot ethanol, chloroform or benzene. In this way, a high molecular weight polyethylene molecularly oriented molded product having high elastic modulus and high strength can be obtained.

The stretching operation can be carried out in one stage or in 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 5.
It is desirable to carry out the stretching operation so that the stretching ratio is 100 times to 100 times, preferably 10 to 80 times.

In general, it is advantageous to carry out the stretching in multiple stages of two or more stages. From the second stage onward, it is preferable to continue the stretching operation of the molded body at a temperature of 120 to 160°C, which is higher than the first stage stretching temperature.

When the polyethylene molded body is stretched in this way, the degree of orientation is 0.95 or more, preferably 0.96 or more, more preferably 0.98 or more, particularly preferably 0.99 or more, and the A high-molecular-weight polyethylene molecularly oriented molded article satisfying the relationship shown can be obtained.

The molecularly oriented molded product of high molecular weight polyethylene thus obtained can be heat treated under restrictive conditions if desired.

This heat treatment is generally carried out at 140-180°C, particularly at 150-180°C.
It can be carried out at a temperature of 175° C. for 1 to 20 minutes, especially 3 to 10 minutes.

The heat treatment further progresses the crystallization of the oriented crystal parts, resulting 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.

Effects of the Invention The polyethylene molecularly oriented molded article according to the present invention has excellent moldability of the raw material high molecular weight polyethylene during its production, has excellent mechanical properties, and can be made thin. Utilizing this characteristic, the molecularly oriented molded article according to 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. be.

Further, the filament-shaped high molecular weight polyethylene molecularly oriented molded product can also be used as reinforcing fibers for various resins such as epoxy resins and unsaturated polyesters, synthetic rubbers, and the like. In addition, because this filament has high strength and low density, it can be particularly lightweight compared to conventional molded products using glass fiber, carbon fiber, holon fiber, aromatic polyamide fiber, aromatic polyimide fiber, etc. It is valid. Similar to composite materials using glass fiber etc., U D
[Urlit Di+ec+ion+l) laminate,
SMC (SbeetMolding Compou)
nd), BMC (Bulk Molcling
It is expected to be used in various lightweight, high-strength fields such as automobile parts, boat and yacht structures, and electronic circuit boards.

Furthermore, when the high molecular weight polyethylene molecularly oriented molded article according to the present invention is subjected to corona discharge treatment, the adhesiveness is greatly improved or the tensile strength is hardly reduced.

The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Ethylene with a molecular weight of 5.5X105 (intrinsic viscosity measured in decalin at 135°C 6.56 r/g)
3 of propylene copolymer (ethylene content 999%) and paraffin wax (melting point 69°01 molecular weight 490)
A mixture having a weight ratio of 0 to 0 (weight ratio) was melt-spun under the following conditions. First, 0.1 part by weight of 3,5-dimethyl-111-butyl-4-hydroxytoluene was added to this mixture as a process stabilizer per 100 parts by weight of the high molecular weight ethylene-propylene copolymer. Next, the mixture was melt-kneaded using a screw extruder at a set temperature of 190°C, and then the melt was passed through a spinning die with an orifice diameter of 2 mm attached to the extruder at a shear rate of 25 seconds and a shear stress of 2. 8 X 1.05 dyn/'a (, melt spun under the condition of Gui temperature 180 ° C. The spun fiber was 180 a
The fibers were taken with an air gap of n at a draft ratio of 33 times, cooled and solidified in air, and were made into undrawn fibers. The degree of orientation of this undrawn fiber was 0.90.

Furthermore, the undrawn yarn thus obtained was drawn under the following conditions to obtain oriented fibers (samples 1 to 3).

That is, the undrawn yarn as described above was subjected to three-stage drawing using a spinning codet roll. At this time, the heating medium in the first drawing tank and the second drawing tank is n-deca, and the temperature is 110°C and 120°C, respectively, and the heating medium in the third drawing tank is triethylene glycol, and the temperature The temperature was 143°C. The effective length of each tank was 50 an. During stretching, the rotational speed of the first copter roll was set at 0.5 m/min and the rotational speed of the fourth codet roll was changed to obtain fibers with a desired drawing ratio. The rotation speeds of the second and third codet rolls were appropriately selected within a range that allowed stable stretching.

Most of the initially mixed paraffin wax was extracted in the first draw tank and the second draw tank. The stretching ratio was calculated from the rotational speed ratio of the first copter roll and the fourth codet roll.

The elastic modulus, tensile strength, and elongation at break of the obtained high molecular weight polyethylene fiber were determined by Tensilon RT manufactured by Orientic Co., Ltd.
Measurement was performed at room temperature (23°C) using an M-100 tensile tester. At this time, the sample length between the clamps was 100 mm, and the tensile speed was 100 wn/min. The elastic modulus is the initial elastic modulus, which was determined from the slope of the tangent to the stress-strain curve. The fiber cross-sectional area required for calculation was calculated from the weight by 81, assuming the density as 0.960 gy'tl. The degree of orientation of the drawn fibers was also determined.

The results are shown in Table 1.

Table 1 Sample Stretching ratio Fineness Strength Elastic modulus Elongation
H Orientation degree sample-] 20 Ili
2.63 66.5 47 ('9τ sample-2
301,63,[ll ε3.0 4.6 0
．． 9f Example 2 Ethylene-
1-butene copolymer (ethylene content 99.9%) and paraffin wax described in Example 1 at 30.70
(weight ratio) was melt-spun in the same manner as in Example 1. However, the die temperature was 170°C. The degree of orientation of the obtained undrawn fibers was 0.91.

Furthermore, the undrawn yarn was drawn in the same manner as in Example 1 to obtain drawn fibers (Samples 4 to 5).

The results are shown in Table 2.

Table 2 Sample Stretching ratio Fineness Strength Elastic modulus Elongation
H Orientation degree (double) (Denier) (G?
) (GPx) (%''' (F) Sample-4259,02,4069,74,40,97 Sample-5307,42,7478,14,10,98 Example 3 Molecular weight is 4.7XiO'' (at 135℃ A mixture of high molecular weight polyethylene having an intrinsic viscosity of 5.8dj?7'g) measured in decalin and the paraffin wax described in Example 1 at a ratio of 30N0 (weight ratio) was melted in the same manner as in Example 1. The fibers were spun to obtain undrawn fibers.However, the trough at this time was 50 times larger.The degree of orientation of the obtained undrawn fibers was 0.90.

Further, the drawn fiber (Sample 6) was drawn in the same manner as in Example 1.
) was obtained.

The results are shown in Table 3.

Table 3 Sample Stretching ratio Fineness Strength Elastic modulus Elongation
Degree of orientation (times) (Denier) (GPa)
(GPai (%) (F) Sample-6404,2
3,32+10.8 3.8 0.98 Comparative Example 1 Polyethylene having a molecular weight of 2.5×IC15 (intrinsic viscosity measured in decalin at 135°C or 3.7 df/g) and described in Example 1 30 with paraffin wax
A mixture of near 0 (weight ratio) was melt-spun in the same manner as in Example 1. The degree of orientation of the obtained undrawn fibers was 085.

Furthermore, the undrawn yarn was drawn in the same manner as in Example 1 to obtain drawn fibers (Samples 7 to 9).

The results are shown in Table 4.

Table 4 Sample - 8405, 31, 2841, 74, 30, 96 Comparative Example 2 30 Nia 0 (weight ratio) of polyethylene similar to that used in Example 2 and paraffin wax described in Example]
The mixture was melt-spun under the same conditions as in Example 1, except that a spinning die with an orifice diameter of 4 was used. The temperature of the spinning die at this time was 170°C. The degree of orientation of the obtained undrawn fibers was 0.88.

Further, the undrawn yarn was drawn in the same manner as in Example 1 to obtain a drawn fiber (Sample 10).

The results are shown in Table 5.

Table 5 Sample Stretching ratio Fineness Strength Elastic modulus Elongation
and Orientation Comparative Example 3 Ethylene-propylene copolymer (ethylene content 99.9%) with a molecular weight of 1.2X106 (intrinsic viscosity measured in decalin at 135°C: 11.2 dl/'g) and Example The kneaded product with paraffin wax described in 1.
Melt spinning was carried out in the same manner as in Example 1 except that the die temperature was 190°C.

Note that when the die temperature was 190° C. or lower, the viscosity of the kneaded product was too high, making spinning difficult.

Furthermore, when the undrawn yarn was drawn in the same manner as in Example 1, the fiber (sample 11) was easily broken and steady drawing of 10 times or more was impossible.

The relationship between the tensile strength S, weight average molecular weight M, and fineness of the high molecular weight polyethylene fibers as described above is as follows:
It is shown in Table 6.

In addition, in each Example and Comparative Example, spinnability and drawability during production of high molecular weight polyethylene fibers were evaluated.

The results are shown in Table 6.

In addition, each Example (Samples 1 to 6) and Comparative Examples (Samples 7 to 1
FIG. 1 shows the relationship between fineness (denier) and strength (GPa) of the high molecular weight polyethylene fiber obtained in Example 0). In FIG. 1, the numbers indicate sample numbers.

Table 6 ◎ Very good ○ Good△ Possible × Difficult example 4 Intrinsic viscosity measured in decalin at 135°C is 5.6 dl
/g and has a molecular weight of 4.5x105.
A combination of propylene copolymer (ethylene content 99.9%) and paraffin wax (melting point 69°C, molecular weight 490)
A mixture of 0.70 (weight ratio) was melt-spun under the following conditions. First, 0.1 part by weight of 3,5-dimethyl-fe+I-butyl-4-hydroxytoluene was added as a process stabilizer to this mixture based on 100 parts by weight of the above ethylene-propylene copolymer.

Next, the mixture was melt-kneaded using a screw extruder at a set temperature of 190°C, and then the melt was passed through a spinning die with an orifice diameter of 2 mm attached to the extruder at a shear rate of 25 IEC and a shear stress of 2.6X. 105 days
Melt spinning was carried out under the conditions of n/ai and a die temperature of 180°C.

At this time, the spun fibers were
Taken at twice the draft ratio, cooled and solidified in the air,
It was made into an undrawn fiber.

The degree of orientation F of this undrawn fiber was 0.9.

Furthermore, the undrawn fibers were drawn in the same manner as in Example 1 to obtain fibers.

Table 7 shows the tensile properties of the drawn fibers (Samples 12 to 14) obtained.

Table 7 Sample Stretching ratio Fineness Strength Elastic modulus Elongation
degree of orientation (double) (denier) 1GPa)
(GPa> (%) (F) Sample-122011
,62,1565,34,50,96 sample-13307
, 72, 4] 81.6 4.3 0.97 Example 5 A molten mixture similar to that described in Example 4 was heated at a shear rate of 41 sec and a shear stress of 3. ], X105dyn/
Spinning and drawing were performed in the same manner as in Example 4 except that the CCD and die temperature were 170°C. The degree of orientation F of the undrawn fibers was 0493.

Table 8 shows the tensile properties of the drawn fibers (Samples 15 to 19) obtained.

Table 8 Sample Stretching ratio Fineness Strength Elastic modulus Elongation
Degree of orientation (double) (Denier) (GP
i) (GPa) (%) (F) Sample-152011, 82, 2069, 54, 30, 96
Sample-163 [IT, 5 2.52
B5. + 3.9 (1,91 sample-I?
40 5.7 2.85 98.8
3.5 0.98 Example 6 Intrinsic viscosity measured in decalin at 135°C is 5.7d
l/g and a molecular weight of 4.6 x 105 (ethylene content 99.8%) and the paraffin wax used in Example 4.
The mixture (weight ratio) was melt-spun in the same manner as in Example 4. However, the shear rate at this time was 33 IEC, the shear stress was 2.9 x 105 dyn/al, and the die temperature was 170°C. The degree of orientation F of this undrawn fiber is 0.
It was 91. Further, the undrawn fibers were drawn by the method described in Example 4 to obtain drawn fibers.

Table 9 shows the tensile properties of the drawn fibers (Samples 18 to 19) obtained.

Table 9 Sample Stretching ratio Fineness Strength Modulus Elongation Orientation degree (I@) (Denier) (GPa)
fGPa) (%) (F) Sample-1
8259,42,0072,24,0 (L96 sample-1
9307,62,0675,73,90,97 The tensile strength S in the high molecular weight polyethylene fiber as described above,
Table 10 shows the relationship between the weight average molecular weight M and its fineness.

Furthermore, in each of the Examples and Comparative Examples, spinnability and drawability during production of high molecular weight polyethylene fibers were evaluated.

The results are shown in Table 10.

Moreover, the relationship between the fineness (denier) and strength (GPa) of the high molecular weight polyethylene fibers obtained in each example (samples 12 to 19) is shown in FIG. In FIG. 1, the numbers indicate sample numbers.

\ \ \ \ \ \ \ \ \ \ \ \ \ Table 10 ◎ Very Good Example 7 Sample-3 manufactured in Example] was subjected to corona discharge treatment manufactured by Tomoe Kogyo Co., Ltd., and the distance between the bar-shaped electrodes was set to 1.0 mm. , corona discharge treatment was performed once at an irradiation dose of 75 W/'rd·min. The tensile strength of the fiber after treatment was 3°16 GPa (retention rate 95%).

Comparative Example 4 A 595 (weight ratio) mixture of polyethylene and decalin having a molecular weight of 2.2×1.06 (intrinsic viscosity measured in decalin at 135° C.: 17.OdA/g) was spun under the following conditions.

First, 0.1 part by weight of 3,5-dimethyl-+ert-butyl-4-hydroxytoluene was added as a process stabilizer to 100 parts by weight of the mixture, and the mixture was poured into a separable flask sealed with nitrogen and heated at 180°C. The mixture was stirred for 1 hour to form a homogeneous solution.

Next, the solution was put into a spinning tube and heated to 180°C under a nitrogen atmosphere.
The solution was allowed to stand for 2 hours at a temperature of 100 to degas the solution. The solution is extruded from a spinning die with a diameter of 2M into a coagulation tank (water bath) located 30cm below without applying a draft twice or more,
It was made into a gel-like filament. After winding this gel filament onto a bobbin at a speed of 1 m/min, the bobbin was
The gel filament was immersed in a hexane bath at room temperature to replace decalin, a liquid component of the gel filament, with n-hexane. moreover,
It was taken out from the n-hexane tank and thoroughly dried under vacuum at 50°C.

Next, 50 x 7” dry fibers were placed in a heat tube sealed with nitrogen.
Three-stage stretching was performed using four codet rolls. The effective length of each heat tube was 50 cm, and the temperature inside the first heat tube was 110°C, the temperature inside the second heat tube was 130°C, and the temperature inside the third heat pipe was 140°C. The stretching ratio was determined by the rotation ratio of the first codet roll and the fourth codet roll, and the drawing ratio at this time was 60 times. 2nd, 3rd
The rotational speed of the codetrol was appropriately selected within the range that allowed stable operation. The physical properties of the obtained polyethylene fiber were that the intrinsic viscosity was 14.0 dI/g, the fiber denier was 21, and the tensile strength was 2.85 GPa.

The polyethylene fibers were subjected to corona discharge treatment under the same conditions as in Example 3. The tensile strength of the fiber after treatment is 1.7
It was 5 GPa (retention rate 61%).

Example 8 An ethylene-4-methyl-1-pentene copolymer (ethylene content 999%) with a molecular weight of 6.0×ICI5 (intrinsic viscosity measured in decalin at 135° C. of 69d7”/”’g) was used. A 35:65 (weight ratio) mixture with paraffin wax similar to that used in Example 1 was heated at a shear rate of 33 sec and a shear stress of 5.2 x 10'' dy.
An undrawn fiber was obtained in the same manner as in Example 1, except that n/'ai, die temperature was 170° C., and draft ratio was 60 times. The degree of orientation of the obtained undrawn fibers was 0.94.

Furthermore, the obtained undrawn fibers were drawn in the same manner as in Example 1 to obtain drawn fibers (samples 20 to 22).

The results are shown in Table 11.

Table 11 Sample-20IC13,62JG 47.3 6.
4 D, 96 samples - 21158,72,647LD
5.4 (1,!17 Example 9 Ethylene-butene-1 copolymer (ethylene Content 99.
9%) and paraffin wax similar to that used in Example 1 in a 40:60 (weight ratio) mixture at die temperatures of 1 and 7.
An undrawn fiber was obtained in the same manner as in Example 1 except that the temperature was 0° C. and the draft ratio was 60 times. The degree of orientation of the obtained undrawn fibers was 0.91.

Furthermore, the obtained undrawn fibers were drawn in the same manner as in Example 1 to obtain drawn fibers (samples 23 to 25).

The results are shown in Table 12.

Table 12 Sample Stretching ratio Fineness Strength Elastic modulus Elongation
Orientation degree sample-23158, 92, 5458, 45,
50,96 samples - 24207,62,737G, 3
5.1 0.97 Comparative Example 5 Molecular weight is 1. ．． A 50.50 (weight ratio) mixture of ethylene polymer of 7×105 (intrinsic viscosity 2.3 d//g measured in decalin at 135° C.) and paraffin wax similar to that used in Example 1 was sheared. Speed 25se
c. An undrawn fiber was obtained in the same manner as in Example except that the shear stress was 1.9XIQ5dyn/ad. The degree of orientation of the obtained undrawn fibers was 0.85.

Furthermore, the obtained undrawn fibers were drawn in the same manner as in Example 1 to obtain drawn fibers (sample 26-2 g).

The results are shown in Table 13.

Table 13 Sample-273012, 80, 643185, 8G, 95
The relationship between the tensile strength S, weight average molecular weight M, and fineness of the high molecular weight polyethylene fibers as described above is as follows:
It is shown in Table 15.

Further, FIG. 1 shows the relationship between the fineness (denier) and strength (GPa) of the high molecular weight polyethylene fibers obtained in each example (samples 20 to 30).

In FIG. 1, the numbers indicate sample numbers.

Comparative Example 6 A 20:80 (weight ratio) of an ethylene polymer having a molecular weight of 4.5×105 (intrinsic viscosity measured in decalin at 135° C.: 4.5 dI/g) and a paraffin wax similar to that used in Example 4. ) at a shear rate of 10+ec
An undrawn fiber was obtained in the same manner as in Example 1, except that the shear stress was 1.5×10"drn/'ri. The degree of orientation of the obtained undrawn fiber was 0.88.

Furthermore, the obtained undrawn fibers were drawn in the same manner as in Example 1 to obtain drawn fibers (samples 29 to 30).

The results are shown in Table 14.

Table 14 Table 15

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between fineness and strength in high molecular weight polyethylene fibers obtained in Examples (Samples 1-6, Samples 12-25) and Comparative Examples (Samples 7-10, 26-30). be.

Claims (1)

[Scope of Claims] A molecularly oriented molded article made of high molecular weight polyethylene having a weight average molecular weight of 300,000 to 600,000, having a fineness of 15 deniers or less and a tensile strength of at least 1.7 GPa or more. Moreover, its tensile strength S (GPa), its weight average molecular weight M (g/mol), and its fineness D (denier) are expressed by the formula [I] M/300,000×D^-^0^. ^3<S<(M-
100,000)/10,000×D^-^1^. ＾0
^8...A molecularly oriented molded article characterized by being in a range that satisfies the relationship expressed by [I].