JPS5971411A - Production of macromolecular substance - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a novel stretch-molded polymeric material.

British Patent Application No. 10746/73 describes molded articles,
In particular, Young's modulus (dead load creep) is 3 x
There is a description of high-density polyethylene filaments, films, and fibers with a weight average molecular weight (Mw) of 200.00.
0 or less, the number average molecular weight (Mn) is 20,000 or less,
When Mn is 104 or more, MW/Mn is 8 or less, and Mn is 1
04 or less, a polymer with Mw/Mn of 20 or less is cooled from a temperature near its melting point at a rate of 1 to 15°C per minute,
High modulus polyethylene molded articles have been obtained by then stretching the cooled polymer.

We subject the crystalline polymer to a heat treatment under conditions that substantially reduce the likelihood that more than one (i.e., two or more) given molecular chains will be incorporated into crystalline lamellae, It has been found that a high modulus polymer material having a Young's modulus of more than 30 N/rd can be obtained by stretching the polymer at a speed and temperature such that the molecules become almost completely linear.

That is, the present invention provides stretch-molded high modulus oriented polyoxymethylene (
Book and 11) 200,000 (Mw<300000(
W: high-density polyethylene with weight average molecular weight (2)
High-density polyethylene with weight average molecule M (λfw) < 200,000 and number average molecule i (Mn) ≥ 20,000, and (3) weight average molecular weight (MW) < 200,000
, number average molecular weight (Mn) < 20000 b YoC
A material having a Young's modulus of 30 N/yf, selected from the group consisting of high-density polyethylene, where l"Mn'> 10 (D @MwZ pain) > 8 and in < 104, w7' M n > 20. The present invention relates to a larger high modulus oriented high density polyethylene stretched molded product.

As used herein, a crystalline polymer refers to a polymer that can form a crystalline or semi-crystalline structure when its melt is cooled. The present invention refers to polyoxymethylene and polyethylene, especially high density polymethylene.

High density polyethylene is defined herein as containing at least 95 weight percent ethylene and having a density of 0.91 to 1. (1
/7 is defined as a substantially linear ethylene homopolymer or copolymer. The density is British Standard Specification A3412 (1
966) and annealed according to Appendix B(1) of the same, such as those obtained by polymerizing ethylene in the presence of transition metals, according to the Pritish Standard Specification. g 2782 (1970)
It was measured by method 509B of .

The crystalline polymer should have a suitably high weight average molecular weight so that the shaped article after stretching retains favorable physical properties in terms of strength and elongation at break. However, a high concentration of long chain moieties increases the chances that a given molecular chain will be introduced into -more crystal lamellae before stretching. Hereinafter, in this specification, such a molecular chain will be referred to as an interlamellar molecular chain.

Although the present invention is not limited by any particular theory, it is believed that an excess of interlamellar chains reduces the degree of molecular orientation and linearization obtained by stretching due to increased permanent morphological entanglement, resulting in an optimal It is thought that this prevents the acquisition of physical properties.

The preferred weight average molecular weight (M,w) of the polymer is 5o
, ooo to 250,000. More preferably 50°0
00 to 150,000, number average molecular weight (Mn)
C5. 25,000 from OQQ, and 15,000 from 5.000. It is usually advantageous to avoid high Mw to Mn ratios, so that the deformation at the molecular level is more uniform during the attenuation process. A preferable ratio of Mw to Mn is 30 or less. In particular, a relatively narrow molecular weight distribution, for example when Mn is 104 or more, Mw/Mn is 1O or less (preferably 8 or less, most preferably 6 or less), and Mn
When Mw/Mn is 104 or less, good results can be obtained by using a polymer having Mw/Mn of 25 or less (most preferably 15 or less).The molecular weights quoted in this specification were measured by gel permeation chromatography. It is something.

Heat treatment can, for example, cause a substantial portion of molecules with intermediate molecular weights to crystallize into discontinuous, highly ordered folded chain lamellae, while small amounts of very large and very small molecular weight molecules are separated. However, in rare cases where crystal heads are interconnected, molecular weight fractionation has the effect of reducing the possibility of introducing excess molecular chains into one or more lamellae.

This effect can be obtained, for example, by the following three methods.

(1) A method of cooling a polymer at a predetermined rate from a temperature at or above its melting point to an ambient temperature at which a desired crystal structure is obtained. In this case, the cooling rate depends on the molecular weight characteristics of the polymer. It is generally necessary to cool the polymer at a rate of no more than 40°C per minute, preferably no more than 20°C per minute,3 with the most preferred cooling rate being no more than 10°C per minute.

(A method in which a polymer is cooled from its melting point or higher to a temperature below its crystallization temperature at a predetermined rate, and then rapidly cooled to ambient temperature. The cooling rate is preferably 1 to 15% per minute.
°C1 most preferably 2-10 °C per minute. Preferably, the polymer is rapidly cooled when the temperature reaches 5 to 20°C below the crystallization temperature. The rapid cooling should preferably be at a rate of less than ,000°C per minute.

(3) A method of rapidly cooling a polymer from a temperature at or above its melting point to near its crystallization temperature and holding the polymer at that temperature for a sufficient period of time to cause crystallization. Preferably, the polymer is heated to a temperature within 15°C of the crystallization temperature.
Hold for 10 minutes. The polymer is then preferably rapidly cooled to ambient temperature.

Optical micrographs of samples prepared by methods (1), (2) and (3) each show that a polymer with a given molecular weight characteristic has a macrostructure containing uniformly oriented regions of various sizes throughout the polymer. It shows that it is forming. In high density polyethylene, the stiff area can reach up to 15μ.

The conditions used in methods (1), (2) and (3) are selected based on the molecular weight characteristics of the polymer. However, in general, if the polymer has a particularly narrow molecular weight distribution, extremely slow cooling (1/min.
'C and below) A crystal structure suitable for elongation is not generated. Very fast cooling of more than 40°C per minute in methods (1) and (2) and holding longer than necessary at the crystallization temperature in method (3) have also been found to be detrimental. .

Figures 1a, 1b and 1c represent the crystal structures produced by methods (1), (2) and (3) of the invention, respectively, in the case of high density polyethylene.

As an alternative method of forming a crystalline structure that substantially reduces the possibility that a given molecular chain will be incorporated into one or more crystalline lamellae, the polymer can be heated from a temperature at or above its melting point to a temperature well below its crystallization temperature. There is a method of rapidly cooling to a temperature to obtain a relatively low degree of crystallinity. This method, namely the method (
4) significantly reduces the thickness of the spherulites and produces a crystal-containing structure surrounded by large amorphous regions, thereby reducing the number of interlamellar molecular chains.

Preferably the cooling rate is less than 1,000°C per minute and most preferably less than 5000°C per minute throughout the crystallization temperature range and the polymer is cooled to ambient temperature or below.

Depending on the molecular weight characteristics of the polymer, it may be advantageous to reheat the cooled polymer to increase the size of the crystalline regions prior to attenuation.

The optical micrograph of the sample produced by method (4) clearly shows that it has a string-like spherulite structure as in the conventional method, but the spherulites are small and cannot be clearly distinguished. can. FIG. 1d shows the crystal structure produced by the method of the invention [4] in the case of high-density polyethylene.

Structures formed with different heat treatment methods do not necessarily deform in the same way under a given condition. There will be an optimal elongation method for each structure. If there is an apparent molecular orientation in the unstretched material, elongation may be undesirably restricted.

The crystallization of polymers has been widely studied and explained in books such as Listerization of Polymers (Chapter 8: Crystallization Kinetics and Mechanisms) by Elle Mandelkaan, published by McCraw-Hill in 1964. There is. By observing changes in properties such as density and specific volume, it is understood that crystallization occurs in stages. There is a time lag until crystallization is observed, but as soon as it is observed, it proceeds naturally and almost autocatalytically accelerated. Eventually, the crystallization reaches a state of pseudo-equilibrium, after which crystallization proceeds very gradually over a long period of time and in a small but discernible amount. This crystallization process is continuous, and a plot of the rate of crystallization versus time is sigmoidal, with no abrupt changes or discernible discontinuities.

The rapid crystallization is called primary crystallization, and the slow crystallization stage is called secondary crystallization. It is believed that secondary crystallization is disadvantageous in obtaining high modulus, and while some secondary crystallization can still provide favorable properties upon elongation in some types of polymers, It has been found that the highest modulus is obtained when the process is not dominated by secondary crystallization. At least method +11
, (21 and (3)), it has been found to be advantageous to allow the crystallization to proceed until the usually rapid initial crystallization is substantially complete. This can be tracked by measuring density.

Methods +1], +21 and (3), the maximum elongation that can be achieved (maximum modulus obtained) for a given heat treatment and given polymer increases with increasing density until the polymer density reaches an optimum. To increase. However, as the polymer density increases above the optimum density, the maximum elongation obtained will decrease. By attenuating samples of different densities under the same conditions, it is possible to determine the optimal polymer density for a given attenuation condition.

After heat treatment, the polymer is stretched at a temperature and at a rate such that the deformation ratio is at least 15, preferably at least 20. It is believed that the high degree of elongation necessary to obtain high modulus is achieved by uniform stretching and consequent orientation of the polymer, which corresponds at the molecular level to the degree of unfolding of the molecules in the crystalline lamellae.

A particularly preferred method of attenuation is one in which the tensile force is less than or equal to the tensile strength of the polymer, but at a speed and temperature sufficient to cause linearization of the molecules by inducing deformation in the plastic that exceeds the elongation that would result from flow stretching. The polymer is stretched to a high stretching ratio. Preferably the draw ratio is at least 20.

Optimum stretching conditions depend to an extent on the nature of the polymer and its thermal history. In general, it is preferable to stretch the polymer relatively slowly, for example, between relatively movable clasps at a rate of at least 1 cm per minute, usually between lO and 20 cm per minute, at a temperature of at least 40°C below the melting point of the polymer. or stretched on a stretching frame at a temperature of 5 to 20° C. below the melting point at a rate of 30 to 150 C+++ per minute.

The physical properties of the polymeric material may be further improved by stepwise stretching, with pauses in the polymer between each step, and intermittent stretching.

Preferably, polymers with relatively small cross-sections are subjected to a stretching process, and the invention is particularly suitable for the production of fibers and films. In particular, continuous filaments are produced by melt spinning or drawing on a drawing frame. For convenience, the fiber diameter or film thickness before stretching is preferably 1M or less.

As used herein, the deformation ratio or stretching ratio is defined as the ratio of the length after treatment to the length before treatment or the ratio of the cross-sectional area after stretching to the cross-sectional area before stretching.

In the method of the present invention, for example, the Young's modulus defined in F is 3×1o.
N/n1 or more, in some cases at least 6×1ol
ON/, ++ polyethylene polymers can be produced. Since the Young's modulus of a polymeric material depends to a large extent on the method of measurement, in this specification, the Young's modulus is measured as the measured modulus at 21°C when a tension of 0.1% is applied for 10 seconds by a dead-loading creep test. It is defined as

This test method was developed by Gupta and Ward: Journal of
Macromolecular Science and Physics, Bl, 373 (1967).

It can be seen that the method of the invention results in polymer molecules that are substantially perfectly linearly arranged upon plastic deformation. This molecular orientation is often -axial, but by appropriate stretching it is also possible to obtain biaxially oriented polymers. Substantially perfect orientation can be determined by physical measurements such as X-ray diffraction analysis and nuclear magnetic resonance analysis.

According to the method of the invention, a polyethylene material having a Young's modulus of 5XlON/d or more is obtained.

The theoretical Young's modulus of polyethylene is 24×101 ON/bat, and it can be seen that the polymers of the present invention come very close to this value.

The polymeric material according to the invention is manufactured in a monolithic structure. The present invention will be explained below with reference to Examples.

Example 1 High-density polyethylene (described later) was heated to 190°C with a diameter of 0.1α.
The diameter is 0.06 to 0.070 by melt spinning through a die.
obtain an isotropic filament.

diameter 5. rotating the filament at 2.3 rpm.
Roll it up onto a 5m cylinder. The polymer cooling rate is set at 5°C per minute, and the structure that forms when the polymer temperature reaches 115°C is maintained by rapid cooling. Length 3~4c1
n samples at 72°C using an Instron tensile tester.
The film is stretched for 0 to 45 seconds at a cross-stretching speed of 20 Crn/min. The stretching ratio is determined based on the change in the cross section of the filament.

Two types of polymers selected from commercially available BB (IIP) high density polyethylene are used as samples. One is 0
75-60 grade, temperature 190℃ and load 2.14
Melt flow index when measured in kQ8.
0, Kai: 14,450, iW: 69.100. The others are Ri-gideX9,
Melt flow index 0.9°Mn: 6.0
, 60, MW: 126,600. The 10 second Young's modulus is measured at room temperature (21°C). 075-60 grade has a narrow molecular weight distribution, namely Mw/Mn -4.8%, draw ratio: 20, -1-7g ratio 4. OX 101ON/
A stretched product of d is obtained. On the other hand, Rigidex 9 has a wide molecular weight distribution, that is, a high Mw/Mn=20.9.
w value, resulting in a stretched product having a fairly low Young's modulus. Continuous filaments of the materials described above can be stretched on a stretching frame to give similar results.

Example 2 High-density polyethylene pellets were placed between two copper plates.
0.05-0.07 by compression molding at ℃
Obtain a sheet of ff thickness. The sheet is removed from the press, slowly cooled to 100°C at a rate of 7 to 9°C per minute (measured on the surface of the copper plate), and then placed in cold water for quenching. Rectangular samples 2 cm long and 0.5 cm wide are stretched using an Instron tensile tester at 75° C. for 70-90 seconds at a crosshead speed of 10 cm per minute. The stretching ratio is measured by making marks at intervals of 0.2 or 0.1 m on the surface of the sample before stretching.

Two grades of commercially available BP high-density polyethylene were used as samples.

Rigidex 50 has a melt flow index of 5.5.
Mn: 6,180, Mw: 101,450, 14
0-60 grade has a melt flow index of 12, M
n: 13,350, Mw: 57°800. The maximum stretch ratio for Lysidex 50 is 30.140-6
The maximum draw ratio for the 0 grade is determined to be 37-38.

The Young's modulus of representative samples was measured at room temperature for 10 seconds, and the results are shown in the table below.

Table 1 The following Examples 3-5 demonstrate that the maximum draw ratio obtainable occurs at the optimum density, and that the optimum density is a function of the heat treatment conditions.

Example 3 High-density polyethylene (Rigidex 25, B.B.
Limited product, MW: 98,800゜Mn: 12,
160 mm between two (7) copper plates (0.5 mm thick 950)
A film is made by compression molding at ℃.

The plate is removed from the press, wrapped thickly in raw silk, and the polymer is cooled at a rate of 5° C. per minute as measured by a thermocouple. When the temperature reached 120°C, the plate was placed in a glycerin bath maintained at 120°C and 0 (do not enter the bath) ~1
Hold for 0 minutes. The density of the film is measured using a density column. A dumbbell-shaped sample of the film is stretched using an Instron tensile tester at 75° C. for 60 seconds at a crosshead speed of 10 CM/min. 0.2 or 0.2 to the sample before stretching. Marks are made at intervals of lz, and the stretching ratio is determined based on the increase in length of the sample after stretching.

Table 2 shows the influence of holding time at 120°C on density and maximum stretching ratio.

Example 4 Immediately after removing the plate from the press, it was immersed in a glycerin bath and the polymer was heated at 160 °C at a rate of 40 °C per minute.
The same process as in Example 3 was carried out except that the temperature was lowered from 120°C to 120°C. Table 2 shows the effect of density on drawing ratio.

Example 5 A polymer was sandwiched between aluminum foils, and the whole was sandwiched between copper plates. Processing is carried out in the same manner as in Example 3, except that only the copper plate is removed immediately before placing the polymer and aluminum foil in the glycerin bath.

The cooling rate is 400°C per minute. The holding time at 120°C was less than the density and maximum stretching ratio, and the effect is shown in Table 2.

Table-2 Example 6 High-density polyethylene (Rigidex 140-60, a product of BP Limited, Mw: 67°800,
Mn: 13,350) is extruded at 180° C. through an extrusion port with an orifice of 0.9 am and the resulting filament is passed through a glycerin bath maintained at 120° C. before winding. Vary the position of the bath below the extrusion port and the retention time of the filament in the bath. The temperature of the filament entering the bath is approximately 135°C. The filaments are drawn under conditions similar to those described in Example 3. Table 3 shows the conditions for spinning and drawing and the properties of the drawn filaments. The modulus is the dead modulus described by Gupta and Ward in Journal of Macromolecular Science and Physics Bl, 373 (1,967).
Load creep test (measured at 21°C).

When the spun filament of Example 6 is cut and observed under a polarizing microscope, regularly oriented regions uniformly distributed throughout can be seen. This region represents the initial flux in spherulite growth.

Example 7 The process is as in Example 6, except that the spun filaments are wound up at a speed of 150117 n/min and the bath temperature is varied from 60 to 125°C. The temperature of the filament upon entering the bath is measured with an infrared pyrometer. The properties of the spun filaments are shown in Table 4.

Example 8 High density polyethylene (Rigidex 140-60) is spun into single fibers and cooled using the same equipment as in Example 6. The employment conditions are as follows.

Extrusion amount: 0.3 fl 1 minute Extrusion temperature
180°C Winding speed 5 feet/min Cooling distance from spinneret 7.5cm Cooling temperature 120°C Cooling length 5QCm The obtained drawn yarn was drawn at a drawing frame on pins maintained at 130°C at a drawing ratio of 23, 8. Stretch continuously at a stretching speed of 1 ft/min. The obtained drawn filament has a strength of 6.7
g, p, d tex , cutting elongation 2.9%, creep modulus 450 x 108 N/door.

Example 9 Samples of Rigidex 50 and 140-60 grades are sandwiched between metal plates at a temperature of 160°C, and after compression molding are cooled to room temperature at a non-linear cooling rate of less than 0.8°C per minute. A dumbbell-shaped sample with a length of 2-1 to 0.5 was heated to 75℃.
Stretch with an Instron testing machine. The test conditions and results are shown in Table-5.

The significant difference in stretching behavior for samples with the same initial crystallinity is related to the broadening of the molecular weight distribution and therefore also to the molecular weight of the molecules in the amorphous phase.

The optically significant micrograph of the isotropic sample of Rigidex 50 prepared by the method of this example shows regular orientation regions, but the isotropic sample of 140-60 has a clear spherulite structure before stretching. can be seen.

Table-5 Example 10 Rigidex 50, 140-60 grade BXP10 (
Samples of Mn: 168,000 - Mw: 93,800) and Rigidex 9 were placed between metal plates at -160°C.
compression molding and then water cooling to room temperature.

A high stretching ratio can be obtained by stretching a dumbbell-shaped sample with a length of 2σ and a diameter of 0.5 am at 75° C. for different times using an Instron tensile tester. The test conditions and results are shown in Table-6.

Table 6) Since these samples had test limitations, they were obtained by re-stretching the samples that had been stretched for 160 seconds at a time as a provisional continuous deformation method.

Example 11 Polypropylene samples of various molecular weights were passed through a 0.2-diameter die at a ram speed of 0.6 am/min and 110 c/min.
Stretch at 185° C. in air at a winding speed of In. Place the spool about 3 sides from the die. The filaments are drawn on a drawing frame at a winding speed of about 130a per minute. Table 7 shows the test conditions (multi-stage type 1).
Shown below.

Table 7 Table 8 shows the molecular weight characteristics, stretch ratio, and creef modulus of the two types of samples.

Table 8 Example 12 Polyoxymethylene (Delrin 500, DuPont product, &in: 45,000, k'jw/Mn: slightly larger than 2) was heated in air at 180°C or below at a ram speed of 0.6. Isotropic filaments with a diameter of 0.04 to 0.06 c+n are obtained by melt spinning through a die of diameter 0.2 am with a winding speed of about 36σ/min and a winding speed of about 36σ/min. The take-up spool was located approximately 7-7 feet from the die.

The obtained filament was stretched on a drawing frame at a winding speed of 5
It was stretched in two stages for 0-7 minutes. The conditions at that time are shown in Table-9.

Table-9 *) Measured from the movement of marks placed on the surface of the specimen.

Table 1O shows the 10 second Young's modulus determined by dead-loading creep tests at various temperatures.

Table-10

[Brief explanation of drawings]

Figures 13 to 1d show methods (1) to (4) of the present invention, respectively.
) is a micrograph of the crystal structure of polyethylene produced by Patent Applicant National Research Development /'-〈ri/g7 ・r2.9n/suna, k. Procedural amendment (voluntary) ■Indication of the case 1988 Patent Application No. 148689 2 Name of the invention Molded body of cylindrical molecular substance 3 Person making the amendment Relationship to the case Patent applicant Address: Kingsgate House, 66-74 Victoria Street, London, N.D. 1, England Name: National Research and Development Corporation 4th Agent 7th Amendment. (2) Insert the following statement on page 32 of the specification, before the top jth line of the table: (Hereinafter, blank space) "Example iA High-density polyethylene (Uniphos DMDS 2912 manufactured by Uniphos Chemiato AB Co., Ltd.) :MW=224.0
00 and Mn=24,000) were extruded at 235°C through a spinneret with a single orifice of diameter 0.8 mm (spinnere L) to obtain a filament, which was passed through a glycerin bath maintained at 110°C at 5 m/min. It was wound up at a speed of . The distance between the spinneret and the bath surface was approximately 10 cIn, and the immersion time in the bath was 7.5 seconds. The isotropic filaments produced in this manner were then
It was stretched in a conventional two-roll stretching frame through a glycerin bath at . The speed ratio of the supply roll and stretching roll is 30
:1, and the speed of the drawing rolls was 46 m/min. The stretching ratio of the extended sinus fibers calculated from the initial and final cross sections was also 30. The room temperature Young's modulus was determined by the method of Gupta and Ward (J. Macromol, Sci, Phys, Bl.
, 373 (1967)), and the tenacity and elongation at break (exte
tion to 1)re2k) was measured with an Intron Tencil tester at a strain rate of 50 parts per minute. The properties of this sample are shown in the attached Table 1. Example IB A portion of the spun filament of Sample IA was drawn under the same conditions except that the draw roll speed was 56 m/min and the draw ratio was 35. The physical properties of this sample were measured in the same manner as sample iA. The results are shown in Table I. Example IC A part of the spun monofilament of sample IA was drawn (stretched to a draw ratio of 3o on the same drawing frame as A, except that the passing distance through the glycerin bath at a temperature of 120° C. was shortened and the drawing roll speed was changed to 25 m/min. The physical properties of this sample were measured in the same manner as stretched sample iA.The results are shown in Table 1.
40:MW=26,500. Mn=26,000 and melt flow index (BS1050 method) 0
．． 15) was treated according to the method of the present invention. Cage dimensions (gauge dlmenLIon) 2
Dumbbell method samples of L: nn x 0.5 m were cut from a 0.8 mm thick sheet compression-molded between copper plates at 160° C., and then quenched with water at room temperature. Stretching was carried out using an Instron at a constant crosshead speed of 10 crn-7 M degrees per minute at 75 °C.
This was done using a Tencil test machine. The resulting stretch ratio was determined by measuring the i#I separation of ink marks made 0.1 cnr apart on the original sample surface. Initial Modulus Gupta and Ward's Method (J. Macromol, Sci, BI, 373 (1)
967)). The results are shown in Table IT. Example I11 The procedure of Example 1 was repeated except that the compression molded sheet was cooled to 110° C. before cooling with room temperature water. The initial modulus and draw ratio of this sample are shown in Table H. Example IV High-density polyethylene (Araton 7050 manufactured by EI DuPont: Mw=5 o, o OO and Mn=
22,0OO) was extruded at 275° C. as a 7 II/thifilament yarn and wound at 120 m/min. The isotropic yarn produced in this way was then subjected to a three-step drawing process on a heated plate at a final drawing roll speed of 15 per minute.
It was stretched to 7 m and a total stretching ratio of 45. Distortion Lz hell [5 train 1 level) Q, l t
The room temperature initial modulus of G is determined by the method of Gupta and Ward (J. Macromol, Sci, Phys, BI 3
73 (1967)) on an Instron Tencil Tester at an elongation rate of 50% per minute. The physical properties of this sample are shown in Table III. Example ■ High-density polyethylene (Araton 7050 manufactured by E.I. Dipon: MW=60,000 and Mn-22,
000) as a multifilament yarn at 220℃
It was extruded at a speed of 52 m/min and wound up. The isotropic yarn produced in this manner was drawn on a conventional two-roll drawing frame through a glycerin bath at 110°C. The speed ratio between the supply roll and the drawing roll is 25, and the drawing roll speed is 80. It was m. The room temperature initial modulus at a strain level of 0.1% was calculated using the method of Gupta and Ward (J, M2cromol, Sci,
Phys. 13I373 (1967)), and the strength was measured using an Instron Tensile Tester at an elongation rate of 50 parts per minute. The physical properties of the samples are shown in Table IV. Table ■ Table ■ Table ■ Table ■ Above

Claims (1)

[Scope of Claims] 1. A high modulus oriented polyoxymethylene stretched molded product having a weight average molecular weight of less than 300,000 and a Young's modulus of greater than 3×101 ON/d. 2, (11,200,000 (Mw〈300,000 (M
(w: weight average molecular weight), (2) high density polyethylene with weight average molecular weight (MW) < 200,000 and number average molecular weight (Mn) ≥ 20,000, and (3) weight average molecular weight (Mw) <200000, number average molecular weight (Mn) <20000 and Mn>104, Mw/Mn>8, and Mn <104, Mw
A stretched high-modulus oriented high-density polyethylene article having a Young's modulus of more than 30 N/d, selected from the group consisting of high-density polyethylenes having /Mn>20.