JPH01501611A - Process for producing polyethylene products of high tensile strength and modulus and low creep and products thus obtained - 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] A method for manufacturing polyethylene products with high tensile strength and modulus and low creep. and the product thus obtained.The present invention provides high tensile strength , filaments, tapes, films, and chips with high modulus and low creep. Concerning methods of manufacturing products such as tubes, rods and profiles.

Starting from high molecular weight polyethylene solutions, products with high tensile strength and modulus , in particular for producing filaments or tapes. US Patent No. 4 No. 344908, No. 4411854, No. 4422993, No. 4430383 See No. 4,436,689. In these known methods, linear high molecular weight A semi-dilute solution of polyethylene is prepared, e.g., via spinning, into a solvent-containing material, e.g. into filaments, which are continuously thermoreversibly gelled and stretched to achieve high tensile strength. and modulus of the product. The tensile strength and modulus of the product are It is known that the molecular weight of polyethylene increases as the molecular weight increases. Generally at least 4X10 - even at least 6X10', preferably lXl Starting from polyethylene having a weight average molecular weight greater than 0''.

Products obtained by these known methods were found to have relatively high creep. ing.

For example, attempts have been made to reduce creep by irradiating with electron beams.

However, in that case the tensile strength of the product would be greatly reduced. Also, It is described that creep resistance is improved by post-stretching or heat treatment. Yo See Roppa Patent Application Publication No. 205,960. However, very slow stretching and We do not believe this is a technical or economical solution due to the be exposed.

The present invention provides products with high modulus, high tensile strength and low creep; A method of manufacturing such a product is provided.

The present invention provides a polymer having a viscosity-average molecular weight of at least 500,000 kg/kmol. Mix the polyethylene raw material with a polyethylene solvent or solvent mixture, and At a temperature of formed and cooled after or without complete or partial removal of the solvent. In this method, the solid material obtained after cooling is stretched at high temperature. Polyethylene containing 2 to 20 alkyl side chains per 1000 carbon atoms High tensile strength, high modulus and low creep, characterized by using Ren raw material This invention relates to a method for producing polyethylene products.

According to one aspect of the practice of the invention, polyethylene copolymers are used. So In the case of Polyethylene copolymer having a viscosity-average molecular weight of 10@kg/kmol or more is used and contains 3 to 12 alkyl side chains per 1000 carbon atoms. and preferably the side chain contains at most 2 carbon atoms.

According to another embodiment of the practice of the invention, (A) 21 carbon atoms per 1000 carbon atoms. polyethylene containing one or less alkyl side chains and (B) Polymers containing at least 4 alkyl side chains per 1000 carbon atoms A mixture of ethylene is used, with (A) and (B) both containing at least 500 It has a viscosity-average molecular weight of 000 kg/kmol. In this case, component (A) and and (B) are both 6X105 or more, especially 8X10' or more, It is preferable to have a viscosity-average molecular weight of IO@kg/kmol or more, At the same time, the mixture of (A) and (B) preferably has carbon atoms per 1000 carbon atoms.

5 to 10, more preferably 4 to 7 alkyl side chains; Preferably, it contains 5 carbon atoms. The side chain is not long, e.g. 5 carbon atoms ．． If there are 6 or more, the creep reduction decreases and even the tensile strength and modulus were also found to decrease. with polyethylene mixture In this case, the number of side chains in the component with the largest number of side chains is per 1000 carbon atoms. There should be no more than 100, preferably no more than 20.

The present invention further provides 2 to 20 side chains per 1000 carbon atoms; is a methyl or ethyl group, and the viscosity-average molecular weight is at least 500,000 k g/kmol of ethylene polymer for reduced creep and lower modulus. polyester having a tensile strength of at least 70 GPa and a tensile strength of at least 2.0 GPa; Regarding tyrene products. The product according to the present invention is a poly? (Polymer), V ol, 19. August 1978, p. 969 (Wilding, M.A. et al. ilding, M.A. et al.). plateus creep rate, which is substantially ~100 times lower than the creep rate of products from similar polyethylene without Sai.

The invention inter alia provides a maximum of 3 x 10-'5ee-', preferably a maximum of 2 x 10 -'5ee-', more preferably IX10-'5ee-' or more (measured at 50℃ and a load of 0.750Pa), but the tensile strength is particularly low. 2,5 GPa or more, preferably at least 3 GPa and modulus It relates to a polyethylene product with a pressure of 800 Pa. In particular, in the product of the present invention, The aj axis of the crystal unit cell measured by wide-angle X-ray at 20°C and 65% humidity is 7. Not less than 45 Å. The product is in filament, tape or film form It is preferable.

Various solvents can be used in the method of the invention. Suitable solvents are e.g. For example, paraffin, paraffin wax, toluene, xylene, tetralin, such as quince, monochlorobenzene, nonane, decane or mineral oil fruccidin It is a halogenated or non-halogenated hydrocarbon. Obviously, mixed solvents can also be used. can be done.

The concentration of polyethylene in solution depends on the nature of the solvent and the molecular weight of the polyethylene. You can change it by In particular, polyethylene of very high molecular weight, e.g. When using a solution with a concentration of 50% by weight or more, it becomes highly viscous and difficult to operate. It is difficult. On the other hand, for example, when using a solution with a concentration of 0.5% by weight or less, The disadvantages are lower yields and increased costs for solvent separation and recovery. mosquito Thus, in general, concentrations of between 1 and 50% by weight, especially from 3 to 35% by weight, are used. Liethylene solution is used.

The solutions used can be prepared in a variety of ways, e.g. by suspending solid polyethylene in a solvent. , and then stirred at high temperature or the suspension It can be manufactured by changing using a screw extruder.

In the present invention, the conversion of the solution into a tangible solvent-containing substance can be carried out by various methods, for example, The filament is spun through a spinlet with a circular or slit-shaped die, respectively. or by extrusion in an extrusion mode with a deformed die. This can be done.

The temperature during the conversion must be selected above the melting point. This melting point is Of course, the selected solvent, concentration, molar weight and chemical composition of polyethylene and use pressure dependent, at least 90°C, especially at least 100°C is preferred. Of course, this temperature is selected below the decomposition temperature of the polyethylene. .

Optionally, the solvent-containing material may be stretched before cooling, e.g. with a stretch ratio of 2 to 20. I can do it.

The method according to the invention does not substantially remove solvent, preferably air and/or Liquid cooling media, e.g. above the gelling point of tangible solvent-containing substances such as rapid cooling with water. Includes cooling down. The gel point is, of course, somewhat solvent dependent and generally practical. The quality corresponds to the above-mentioned melting point. Preferably, the material is cooled to about room temperature.

The material thus obtained can be stretched continuously. However, e.g. At least some solvent before stretching, e.g. by extraction with loethane It is also possible to remove. Of course, all or some of the existing Remove the solvent, e.g. by bubbling or by carrying out a stretching operation in an extractant. It is also possible to carry out the stretching operation under such conditions.

In the method of the invention, the material is heated to a high temperature, such as the glass transition temperature of polyethylene. Stretch above the temperature and below the decomposition temperature. Preferably, the stretching operation is at about 75°C. conduct. This stretching is preferably carried out in several steps at elevated temperatures.

In the method of the present invention, it has been found that using high draw ratios, it is difficult to draw.

Generally at least 1O1 preferably at least 20, even at least 40 A draw ratio of is used. Of course, if high stretching is applied before cooling, the stretching ratio should be It can also be lowered.

The product according to the present invention requires substantial strength and rigidity, and mass reduction is advantageous. Suitable for all technical applications.

If desired, small amounts of additives, stabilizers, etc. can also be applied in or on the product. .

The invention is illustrated in the following examples without however being limited thereto.

Each characteristic value used in this specification was measured by the following method.

Viscosity - average molecular weight Viscosity of a certain concentration of decalin solution at 135°C according to ASTM D 2857 Based on the dependence, the intrinsic viscosity (η) was measured. Using this (η) in the following equation, the viscosity is - Average molecular weight was calculated.

Mv = 3.64X10'X (77) 1.39 Measurement of strength and elongation The measurement was performed according to JIS-1013. That is, the S-6 curve is 200 Under the conditions of a sample length of xi and an elongation rate of 100 mm/+nin, Toyo Toyo Bouldwin Company The tensile strength and tensile modulus are measured using a tensile testing machine manufactured by The cost was calculated. Tensile modulus is calculated from the maximum slope of the S-S curve around the origin. did.

Ryōdanri 艷danju shosha Polyethylene powder or finely pulverized molded products are mixed to obtain a 10% by weight solution. Sea urchin was dissolved in 0-dichlorobenzene at 120°C. 75MHz of this solution The CNMR spectra of the Makromol, Chem, 184, 569 (1983) as reference. Furthermore, the degree of branching is determined by the methylene Expressed by the ratio of the intensity of one peak originating from a branch point to the intensity of the peak. Ta.

Size of raJ axis of crystal unit cell Measurement of wide-angle X-ray scattering patterns can be carried out, for example, by Rigaku Denki Company (Ri gaku Denki Company) X-ray generator (RU-3H type) This is done using For measurements, a tube voltage of 45kv and monochromatic with a nickel filter were used. A CuKa wire (λ=1.5418) with a tube current of 70 mA and a copper counter electrode is used. Fi The lament sample is mounted on the sample holder in such a way that the single threads are parallel to each other. So It is preferable that the thickness of is 0.5 to 1.0 mm. The wide-angle X-ray diffraction pattern is , the fiber axes of the filaments are aligned parallel to each other so as to be oriented in the meridian direction. In particular, the size of the ij axis of the crystal unit cell is determined by the equatorial diffraction curve surface (2 Calculated according to the following formula based on the scattering angle 2α at the diffraction peak position of Can be determined.

λ m = 2 X - (person) 2sinα λ=1.5417 people (For correction of scattering angles and other details, see e.g. published by Maruzen Co., Ltd. You can refer to "X-ray Crystallography" edited by Nida IsakanU. Ru. ) 1 to 1 release branch The creep rate used in this specification refers to the elongation of a sample over time after a load is applied to it. The rate of change in For example, the Journal of Polymer Science of Polymer 5 science), 22°561 (1984). This means the deformation rate in flat section creep. of the sample at a certain time (in seconds) When the length is expressed as ff(tXc+++), the creep rate can be calculated using the following formula. .

C(t+a)-12(t) Creep speed = □ (sec-1) go・a [In the formula, go is the length of the unloaded sample (cm): and a is any pole means a short period of time (seconds)] Example 1 Mv is about 1.6X10@kg/kmol, about 10 per 1000 carbon atoms. Polyethylene containing methyl side groups was suspended in xylene to a nominal concentration of 2% by weight. After clouding, adding stabilizers, packaging and degassing, it was melted at 130°C.

The solution was then poured into a stainless steel container, cooled and the solvent evaporated at room temperature. The solvent residue was extracted with dichloroethane. Cut the resulting dry gel film Then, it was stretched in several stages to a stretching ratio of 60 at a temperature gradient of 110 to 130°C. extension The stretched tape has an E-modulus of 85 GPa, a tensile strength of 2, OGPa and The flat part creep rate (ε) of 1O-1 s-1 at room temperature, load 0, 9 GPa I had it.

Example 2 Mv is approximately 1.5X10”kg/kmol, 4 methane per 1000 carbon atoms The procedure of Example 1 was repeated using polyethylene with pendant groups. obtained The tape has an E-modulus of 88 GPa, 2.・I　GPa tensile strength and 3 If the flat section creep rate is X10-"sec-1, the Mv is 1.4 lomol, using polyethylene with one methyl side group per 1000 carbon atoms. and the operations of Examples 1 and 2 were repeated. The obtained tape had a pressure of 900 Pa. E-modulus, tensile strength of 2, 2 GPa and flatness of 8X10'sec-1 It had a creep rate of

Example 3 10% by weight of the polyethylene described in Example 1 in decalin at room temperature. suspended to a nominal concentration of . After degassing, nitrogen is introduced, stabilizer is added and the suspension is , co-rotating twin-screw extruders (Unirna and Pfreidler) with stirring (Werner and Pfleiderer) ZSK type: diameter 30ma+; L/D ratio=27). This extruder consists of two conveying and mixing sections alternately. Equipped with a x30m screw.

At room temperature, the suspension was fed into the intake zone (80°C) and with a residence time of 3 minutes, 2 Extrusion was performed at 180° C. with a screw speed of 0 Orp−.

The resulting solution was spun, cooled in water and extracted with dichloromethane, followed by 12 The gel filament was stretched at 0° C. and at a stretching ratio of 30.

The obtained filament had an E-modulus of 95 GPa and a pull of 2, 7 GPa. Tensile strength and mean ratio of 5X10-@sec-1 at 50°C and load 0, 6 GPa Comparative example B Mv 1.6X10@kg/kmol, 1 methyl per 1000 carbon atoms The procedure of Example 3 was repeated using polyethylene that also had no side groups.

The obtained filament has an E-modulus of 1100 Pa and a tensile strength of 3 GPa. and had a plateau creep rate of 10-'' sec-1.

Example 4 Mvl, 9X10@ and 10 main chain carbon atoms determined by high resolution NMR a powder of polyethylene (A) containing 1.2 methyl side groups per 00; and Mvl, 9X10@ and 1000 carbon atoms in the main chain measured by the same NMR Polyethylene (B) having 13.0 methyl side groups per 10:9 weight ratio Mixed at 0. Then, decalin (90 parts by weight) was added to this mixture (10 parts by weight). Mixed to form a slurry. Mix the substances and have a temperature of 230 °C The transparent homogeneously dissolved substance was melted in a two-wheel screw extruder with a diameter of 0.5u. I pushed it out of my fist.

The extruded melted material was cooled with an air stream at a drawdown rate of 30 cycles/■. in, and then stretched at a draw ratio of 5x in an air heated oven. . That is, the winding speed of the intermediate stretched material is 150 m/m111. Met. unintentionally The substance was heated by 3.2 times in an oven with a length of 50 m under a heated atmosphere. The film was stretched at a maximum stretching ratio of 16.0 times (that is, the total stretching ratio was 16.0 times). At this stage The stretching and winding speed was 100mm/lthin.

Examples 5.6.7 and 8 and Comparative Examples C and D For each example, the branching point The polymer mixing ratio of remer (B) to polymer (A) is as shown in Table 1. carried out except that the maximum stretch ratio of the two-step stretch was changed as shown in Table 1. Using the same polymer as described in Example 4, using the same polymer as described in Example 4 Filaments were produced according to the operation and conditions (final winding speed was 10 (It was constant at 1m/sin).In this way, the strength obtained in the final molded product There was a difference between them.

Table 1 Example Polymer Mixing Ratio Maximum Stretching Ratio 4 (A) and (B) (A): (B) =10:90 16.05 (A) and (B) (A): (B) = 25 near 5 17.56 (A) and (B) (A): (B) = 50:50 20.07 ( A) and (B) (A): (B) = 75:25 22.58 (A) and (B )(A):(B)=90:10 24. OC (A) (A) = 100 24.0 D (B) (B) = 100 10.0 In Table 2, Examples and Comparative Examples The maximum strength of the product obtained at This shows the creep rate when In each example, the product has excellent high properties and It exhibits excellent creep resistance. In particular, in Example 6, the creep resistance of Comparative Example C It exhibits a creep resistance of about 1720 when compared to I will show it in a comparative example. When using 100% branched sea urchin polymer, creep is small, but it is highly sticky. A strong filament cannot be obtained.

Table 2 Examples Tensile strength Number of side chains Creep rate Tensile modulus (GPa) (monoprime number 10 (per second (GPa) 00 pieces) 4 2.1 11.7 3.0XlO-' 68.05 2.8 10.1 1 ．． 0X10-' 100.06 3.1 7.1 6.0X10-@104. 57 3.2 3.1 1. lX10-' 110. OC3,451,21,2 X10-” 118.6D 1.55 13.0 5.0X10-’ 59.0 international search report international search report NL　8700029

Claims (10)

[Claims] (1) Viscosity - polyethylene with an average molecular weight of at least 500,000 kg/kmol Mix raw materials with a polyethylene solvent or solvent mixture at a temperature above the melting point. transform into a tangible solvent-containing material, cool this material to form a solid gel-like material, and remove the solvent. obtained after cooling, with or without complete or partial removal of In the method of stretching the octopus material at high temperature, 2 to 2 carbon atoms per 1000 carbon atoms. High tensile strength characterized by using polyethylene raw material with 0 alkyl side chains Method of manufacturing polyethylene products of strength, high modulus and low creep. (2) Item (1) above using polyethylene copolymer as the polyethylene raw material the method of. (3) Polyethylene has 3 to 12 alkyl side chains per 1000 carbon atoms. The method of item (1) or item (2) above. (4) As a polyethylene raw material, (A) Polyethylene containing 2 or less alkyl side chains per 1000 carbon atoms and (B) Polymers containing at least 4 alkyl side chains per 1000 carbon atoms Using a mixture of ethylene, both (A) and (B) are at least 500,000 The method of paragraph (1) above, having a viscosity-average molecular weight of kg/kmol. (5) the mixture contains 2.5 to 10 alkyl side chains per 1000 carbon atoms; The method of item (4) above. (6) Paragraphs (1) to (5) above, in which the alkyl side chain has at most 2 carbon atoms. ) one or more of the following methods. (7) High tensile strength and high modulus obtained by one or more of the methods set forth in the claims above. products such as filaments, tapes or films of high curvature and low creep. (8) Contains 2 to 20 side chains per 1000 carbon atoms, and the side chains are methyl or or ethyl group, with a viscosity-average molecular weight of at least 500,000 kg/kmol of ethylene polymer with a modulus of at least 70 GPa and a tensile of a filament, tape or film having an elasticity of at least 2.00 GPa Products like. (9) Stability of up to 3 x 10-7 seconds-1 (measured at 50℃ and 0.75GPa load) Crystals of the product with creep rate measured by wide-angle X-ray at 20°C and 65% temperature The product of paragraph (8) above, wherein the "a" axis of the unit cell is at least 7.45 Å. (10) Polyethylene polymer is a copolymer or (A) 1000 carbon atoms polyethylene containing up to 2 alkyl side chains per (B) Polymers containing at least 4 alkyl side chains per 1000 carbon atoms a mixture of ethylene, in which both (A) and (B) are at least 500,000 of paragraph (8) or (9) above, having a viscosity-average molecular weight of kg/kmol. product.