JPH0336929B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing drawn products such as fibers and films that have high elastic modulus, high strength, and more stable quality using ultra-high molecular weight polyethylene. [Prior art and its problems] It is well known that a drawn product with high strength and high elasticity can be obtained by dissolving ultra-high molecular weight polyethylene in a solvent, then spinning and drawing it. For example, as in JP-A-55-107506, JP-A-56-15408, or JP-A-58-5228, ultra-high molecular weight polyethylene is made into a dilute solution with a concentration of about 2 to 10% by weight and then spun. However, a method of stretching to a high magnification has been proposed. In these technologies, it is extremely important that the polymer solution used is uniform, and for this purpose various proposals have been made as methods for adjusting the uniformity of the solution (Japanese Patent Publication No. 60-22010, Japanese Patent Application Laid-open No. 59/1999).
-23123, JP-A-59-223307, JP-A-60-40133, etc.). Even if a homogeneous solution is prepared using these methods, since the solvents used in these methods are all liquid at room temperature, there are various problems as described below. That is, when a homogeneous solution is prepared using the method proposed above and then spun, a large amount of solvent is liberated when the polymer solution is cooled and forms a gel-like substance. Operations such as winding up and winding were rarely performed in order to recover the solvent. In addition, since the gel-like material that has been wound up still contains a considerable amount of solvent, there may be fluctuations in the winding tension, fusion of the wet gel, quality fluctuations due to differences in solvent desorption over time after winding, or stretching. This results in significant non-uniformity in the width and thickness directions of the gel-like material used in the process. On the other hand, various methods have been proposed in which materials are melt-extruded and then stretched using materials that are solid at room temperature and can form a homogeneous system with ultra-high molecular weight polyethylene at high temperatures. For example, JP-A-59-130313, JP-A-60-198220
No. 60-240432, No. 61-8323, etc. These proposals do not mention at all the above-mentioned problems when using a liquid solvent at room temperature. In addition, in these methods, methods for uniformly mixing ultra-high molecular weight polyethylene include a method using a twin-screw kneader, a method of mixing in advance with a Henschel mixer, a V-blender, etc.
Furthermore, methods have been proposed in which the mixture is melt-kneaded and granulated using a single-screw or multi-screw extruder; There are problems such as there is a risk of deterioration or molecular weight reduction, and the inability to stretch to a high degree due to non-uniformity.
For example, JP-A-Sho using a specific paraffin wax.
No. 59-130313 reports results such as that it cannot be carried out if the amount of ultra-high molecular weight polyethylene is less than 15 parts by weight because the uniformity is not sufficient (Reference, Specification, Comparative Example 3). Alternatively, if the amount of ultra-high molecular weight polyethylene exceeds 10 parts by weight, the mixture is kept at high temperature to sufficiently swell, and then heated and kneaded using a kneading machine such as a Banbury mixer to obtain a homogeneous mixture. The method is described (Japanese Unexamined Patent Publication No. 198220/1983, page 2, bottom right, line 20 to page 3, top left, line 4). However, even with this method, since the temperature is kept above the melting point of ultra-high molecular weight polyethylene, the molten polymer particles fuse with each other and form a large mass before swelling, allowing for sufficiently uniform swelling. An effective method for obtaining a uniform melt at high temperatures using a substance that is solid at room temperature has not yet been reported, as the result is a mixture of a molten solid that has not been added and a melt of additives with low viscosity. It was hot due to the situation. [Problems to be Solved by the Invention] As a result of intensive research into a method for producing a drawn product having high strength and high modulus using ultra-high molecular weight polyethylene, the present inventors have found that ultra-high molecular weight polyethylene can be used at high concentrations. It is possible to prepare a solution with excellent uniformity, and furthermore, it is easy to handle and maintains high quality without fluctuations in solvent content from spinning to stretching. We believe that this is an essential condition for producing drawn products with stable quality, high strength, and high modulus of elasticity, and have conducted repeated research. [Means for solving the problem] In other words, using paraffin wax, which is solid at room temperature and has excellent compatibility with the ultra-high molecular weight polyethylene, as a solvent for dissolving the ultra-high molecular weight polyethylene, will reduce the undrawn yarn after spinning. It is easy to handle and is particularly excellent in producing stretched products with stable quality continuously, with almost no fluctuation in solvent content due to winding, etc. Since there is no known method for rapidly dissolving ultra-high molecular weight polyethylene, the optimal method is to mix paraffin wax that has been heated and melted in advance and a liquid organic compound that is compatible with the paraffin wax. It has been found that the melt obtained by mixing ultra high molecular weight polyethylene dispersed or wetted with polyethylene is very homogeneous. Furthermore, by spinning a paraffin wax melt containing ultra-high molecular weight polyethylene prepared using this method under specific conditions and then heating and stretching, it has high strength and high modulus of elasticity, and can be produced for a long period of time. It has been found that a stretched product with stable quality can be obtained even when That is, the present invention provides a method for producing a stretched ultra-high molecular weight polyethylene product, in which paraffin wax that has been heated and melted in advance and a liquid organic compound that is compatible with the paraffin wax are used to wet or disperse a weight average molecular weight 1× A paraffin wax melt obtained by mixing ultra-high molecular weight polyethylene of 10 ⁶ or more is extruded, cooled and solidified after applying at least one draft, and stretched at a stretching temperature of 60 to 140°C. Provided is a method for producing a stretched ultra-high molecular weight polyethylene product characterized by stretching at a stretching ratio of more than 8 times. The ultra-high molecular weight polyethylene used in the present invention is ethylene or ethylene and a small amount of other α-olefins, such as propylene, butene, etc.
Among polyethylenes obtained by polymerizing 1,4-methylpentene-1, hexene-1, etc. using a transition metal catalyst such as Ziegler polymerization, those with a weight average molecular weight of 1 x 10 ⁶ or more are used. It will be done. Those having a weight average molecular weight of less than 1×10 ⁶ are easily dissolved, but it is difficult to obtain sufficiently high performance even when stretched. There is no particular regulation regarding the upper limit, but if the weight average molecular weight is 1×
For those exceeding ¹⁰⁷ , it tends to be difficult to obtain a practical melt. The paraffin wax used in the present invention is solid at room temperature, mainly contains saturated aliphatic hydrocarbon compounds, has a melting point of 40 to 120°C, preferably 45 to 70°C, and has a molecular weight of 2000 or less, preferably
1000 or less, specifically, Dokosan,
n with carbon number of 22 or more such as tricosane and tetracosane
-Alkanes or lower n containing them as main components
- Alkane mixture, paraffin wax separated and purified from petroleum, medium-low pressure polyethylene wax which is a low molecular weight polymer obtained by copolymerizing ethylene or ethylene with other α-olefins, high-pressure polyethylene wax, or medium-low pressure polyethylene wax, Examples include waxes obtained by reducing the molecular weight of low-pressure polyethylene and high-pressure polyethylene by thermal degradation, oxidized waxes such as oxides or maleic acid-modified products of these waxes, and maleic acid-modified waxes. If a material with a melting point of less than 40° C. or a liquid paraffin mixture is used, not only is it not possible to solve various fluctuation factors in the spinning and winding process of the present invention, but various problems arise in production using an extruder. On the other hand, the melting point exceeds 120℃ and the molecular weight is 2000
Even if more than 20% of the paraffin wax is used, it is not only impossible to stretch to a high magnification, but also it is not possible to extract excess paraffin wax before or after stretching. The mixing ratio of ultra-high molecular weight polyethylene and paraffin wax in the present invention is 3:97 to 30:70.
preferably in the range of 5:95 to 20:80. When the amount of ultra-high molecular weight polyethylene is less than 3% by weight, the strand obtained after spinning the melt becomes brittle and unsuitable for drawing. Furthermore, if the ultra-high molecular weight polyethylene exceeds 30% by weight, the viscosity of the paraffin wax melt will be extremely high, resulting in poor moldability and stretchability. The liquid organic compound that is compatible with the paraffin wax used in the present invention is not particularly limited as long as it can disperse or wet the ultra-high molecular weight polyethylene; In order to disperse the ultra-high molecular weight polyethylene and to penetrate the heated paraffin wax into the ultra-high molecular weight polyethylene particles, organic compounds are naturally limited to specific solubility parameter ranges and viscosity ranges. Preferably the solubility parameter ranges from 7.3 to 9.3, and
Preferably, the viscosity at 20°C is 3 c.p or less.
For example, aliphatic hydrocarbon compounds such as n-hexane, n-heptane, n-octane, n-nonane, and n-decane, and aromatic hydrocarbon compounds such as toluene, xylene, betylbenzene, cyclohexylbenzene, dodecylbenzene, and their hydrogen. derivatives, halogen derivatives, etc. Two or more of these may be used as a mixture in any proportion. The solubility parameter here is defined as the square root of the evaporation energy per unit volume, and if the evaporation energy is expressed as ΔE [cal/mole] and the molecular volume of the substance is expressed as V [cc], then The solubility parameter δ is expressed by the following formula. δ = (ΔE/V) ^1/2 The temperature of the heated and melted paraffin wax in the present invention is not particularly limited as long as the temperature in the system after mixing can be maintained at a temperature equal to or higher than the melting point of the ultra-high molecular weight polyethylene. but preferably 140°C or higher and lower than the decomposition temperature of the ultra-high molecular weight polyethylene and paraffin wax, more preferably 150°C or higher and 270°C
The range is as follows. If the temperature of the paraffin wax is less than 140°C, the dispersion of the ultra-high molecular weight polyethylene or the penetration of the wetting liquid into the heated paraffin wax is insufficient, and the swelling of the ultra-high molecular weight polyethylene is insufficient, resulting in macroscopic problems. Therefore, a uniform melt cannot be obtained. Therefore, even if spinning and drawing is carried out as is, the high-performance drawn product with stable quality according to the present invention cannot be obtained. On the other hand, at temperatures exceeding the decomposition temperature, the molecular weight of the ultra-high molecular weight polyethylene decreases, or
The quality changes together with the paraffin wax, and after stretching, a stretched product with stable and high performance cannot be obtained. In the present invention, the method of preparing a melt by mixing the heated and melted paraffin wax and the ultra-high molecular weight polyethylene dispersed or wetted in the liquid organic compound is to mix the heated and melted paraffin wax into a stirred medium. A method of adding the ultra-high molecular weight polyethylene in the dispersed or wet state, or a method of adding heated and melted paraffin wax into the stirred ultra-high molecular weight polyethylene in the dispersed or wet state, and a method of adding the heated and melted paraffin wax and the dispersion or Examples include a method of bringing wet ultra-high molecular weight polyethylene into contact at the same time and then supplying the mixture to an apparatus capable of heating and kneading, but the method is not particularly limited. In addition, in the preparation of a paraffin wax melt containing a high concentration of ultra-high molecular weight polyethylene, the ultra-high molecular weight polyethylene dispersed or wetted in the liquid organic compound is heated to below the boiling point of the liquid organic compound, and then the ultra-high molecular weight polyethylene is heated to below the boiling point of the liquid organic compound. It is also possible to use a method in which the mixture is mixed with heated and melted paraffin wax, or a method in which the mixture thus prepared is passed through an extruder. In the present invention, the method for dispersing or wetting the ultra-high molecular weight polyethylene in the liquid organic compound is not particularly limited as long as it is possible to mix the ultra-high molecular weight polyethylene and the liquid organic compound in an amount equal to or about three times the amount of the ultra-high molecular weight polyethylene. It is desirable that the ultra-high molecular weight polyethylene is dispersed or wetted without settling. For this purpose, a method of adding a viscosity improver or mixing while applying ultrasonic vibration is also used. By mixing the paraffin wax and the ultra-high molecular weight polyethylene using the method of the present invention, it is possible to prepare a uniform paraffin wax melt of ultra-high molecular weight polyethylene over a wide concentration range and with extremely high quality. One of the factors that makes it possible to obtain a stable, high-performance drawn product is that the molten ultra-high molecular weight polyethylene particles are sufficiently swollen before they are fused together, and then uniformly dispersed after swelling to form a uniform melt. it is conceivable that. For this purpose, the liquid organic compound that disperses or wets the ultra-high molecular weight polyethylene must be compatible with the heated paraffin wax, and the liquid organic compound that disperses or wets the ultra-high molecular weight polyethylene must be compatible with the heated paraffin wax, and the liquid organic compound that disperses or wets the ultra-high molecular weight polyethylene must be able to quickly dissolve the ultra-high molecular weight polyethylene beyond its melting point after mixing. It is important that the paraffin wax is heated to a temperature sufficient to raise the temperature and to allow the ultra high molecular weight polyethylene to swell sufficiently in the paraffin wax. In the present invention, when extruding the heated paraffin wax containing the ultra-high molecular weight polyethylene, it is important to apply at least one or more drafts, preferably five or more drafts, and then cool and solidify it. By spinning with a draft, a drawn product having higher strength and higher modulus of elasticity can be obtained compared to when no draft is applied. The draft ratio in the present invention is defined as the ratio between the speed at the exit of the spinneret and the winding speed. In the present invention, the unstretched paraffin wax containing cooled and solidified ultra-high molecular weight polyethylene can be stretched by extracting the paraffin wax in advance using a solvent such as n-heptane and then stretching it, or by directly stretching the unstretched paraffin wax using a heating medium. Any of the methods of stretching in
The above range is below the melting point of ultra-high molecular weight polyethylene. At temperatures below 60°C, it is impossible to draw to a high degree, and at temperatures above 140°C, even if drawn, a drawn product with high strength and high modulus cannot be obtained. The heating medium during stretching in the present invention may be air, steam, inert gas, or solvent, and can be arbitrarily selected depending on the properties of the unstretched material used for stretching. When stretching an unstretched product containing paraffin wax, it is preferable to use a solvent and a heating medium that can simultaneously extract and remove excess paraffin wax during stretching.
Decane, decalin, etc. are preferred. The stretching ratio during stretching in the present invention is preferably at least 8 times. If the stretching ratio is less than the above range, even if an unstretched product obtained by cooling and solidifying at the highest draft ratio is used, a drawn product having high strength and high elastic modulus cannot be obtained. The ultra-high molecular weight polyethylene wax used in the present invention contains various kinds of stabilizers, pigments, dyes, lubricants, and small amounts of inorganic fillers that are usually added to polyolefins, to the extent that the purpose of the present invention is not impaired. Additives that do not significantly inhibit stretching may be used. [Effects of the Invention] The method for producing a drawn product having high strength and high modulus of elasticity using the paraffin wax melt containing ultra-high molecular weight polyethylene of the present invention is superior to the method for producing a drawn product using conventional methods. In particular, in a wide range from low concentration range to relatively high concentration range of ultra-high molecular weight polyethylene, which can improve performance, not only is the quality extremely stable and the loss of raw materials is extremely low, but production efficiency is high. Stable continuous operation is possible in an extremely short period of time and without polymer deterioration.
This is a more effective manufacturing method. The drawn product of ultra-high molecular weight polyethylene produced using the method of the present invention is a high-performance drawn product with extremely stable quality.
It can be used in a wide range of fields such as marine materials, leisure applications, and reinforcement materials, making it an extremely useful product in industry. [Examples] Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 Ultra-high molecular weight polyethylene (Sanhuain-U)
UH900, weight average molecular weight 3.3 × 10 ⁶ ) was weighed so that the final concentration was 5% by weight, and after adding twice the amount of n-heptane to the weight of ultra-high molecular weight polyethylene at room temperature, An ultra-high molecular weight polyethylene suspension was obtained by stirring and slurrying. On the other hand, in a separate container, put the specified amount of paraffin wax (melting point 52-54℃,
(molecular weight 350) was heated and melted at 190°C, and 0.2% of di-tert-butyl para-cresol was added to the weight of the paraffin wax. While stirring this melt, a previously prepared ultra-high molecular weight polyethylene slurry was quickly added to the melt while being careful not to settle. At that time, heating was continued to maintain the temperature inside the container at 190°C. After injection, the ultra-high molecular weight polyethylene particles absorbed the hot paraffin wax and swelled rapidly, causing the melt to swell along the stirring rod, a so-called ``Weisenberg effect.'' At this point, stirring was stopped and the mixture was allowed to stand for 5 minutes, producing an extremely uniform paraffin melt containing ultra-high molecular weight polyethylene. The melt is due to the evaporation of n-heptane,
It contained quite a lot of air bubbles, but after degassing the temperature was 170℃.
The strand was extruded into water through a spinning tube (nozzle diameter: 1.0 mmφ) heated to 500 mL, and wound at a draft ratio of 5 to obtain a continuous strand. No yarn breakage occurred during spinning. The obtained strand was divided into two parts, one was directly stretched in n-decane heated to 130°C, and the other was extracted from the paraffin wax using n-hexane in advance to obtain a dry xerogel. , inlet temperature 120℃ outlet temperature
Stretching was performed using a heating tube set at 135°C. The obtained stretched product was stretched using Tensilon manufactured by Toyo Baldwin Co., Ltd., with a sample length of 100 mm and a tensile speed of 100 mm/min.
Its strength and elongation properties were evaluated under the following conditions. Obtained S
The tensile strength and initial elastic modulus were calculated from the -S curve according to JIS L1013. The results are shown in Table 1. In addition, in order to evaluate the quality variation of the obtained unstretched material,
After winding 300 m of undrawn yarn onto a mm bobbin and leaving it at room temperature for 2 days, extract the three points of the bobbin: the top layer, the middle layer, and the layer in contact with the bobbin. The film was stretched in n-decane heated to . The obtained stretched product was evaluated in the same manner as above, and the results are shown in Table 1. As a result, almost no variation in quality was observed in the undrawn yarn wound on the bobbin. Example 2 Using the same polyethylene as in Example 1, it was weighed so that the final concentration was 8% by weight, and twice the amount of n-decane was added to the weight of the ultra-high molecular weight polyethylene at room temperature. After that, the mixture was sufficiently stirred to obtain an ultra-high molecular weight polyethylene slurry. Meanwhile, in another container, heat and melt a predetermined amount of paraffin wax (melting point 69°C, molecular weight 460) at 200°C, add 0.2% ditertiary butyl paracresol based on the weight of the paraffin wax, and stir. while 200℃
It was kept warm. The previously prepared ultra-high molecular weight polyethylene slurry was added to this mixture in the same manner as in Example 1 to obtain a paraffin wax melt containing uniform ultra-high molecular weight polyethylene. After degassing in the same manner as in Example 1, the spinning tube was heated to 180°C (nozzle diameter 1 mmφ).
The material was extruded into water, and the winding speed was changed to 1, 5, and 15 times the spinneret exit speed. Each film was able to be wound up without stretching. After extracting the paraffin wax from the obtained undrawn yarn using n-hexane, it was drawn using a heating cylinder set at an inlet temperature of 120°C and an outlet temperature of 135°C. The obtained stretched product was evaluated in the same manner as in Example 1, and the results are shown in Table 1. Example 3 Using the same polyethylene as in Example 1, it was weighed so that the final concentration was 20% by weight, and heated at 100°C.
After adding an equal amount of n-decane to the weight of the heated ultra-high molecular weight polyethylene, the mixture was sufficiently stirred to prepare an ultra-high molecular weight polyethylene slurry. On the other hand, a predetermined amount of paraffin wax (melting point: 42-44°C, molecular weight: 300) was heated and melted at 220°C in a container equipped with a stirring device to obtain a paraffin wax melt in the same manner as in Example 1. Since this melt had a very high viscosity, it was supplied to a screw-type single-screw extruder preset at 180°C and extruded into water through a die with a spinneret diameter of 2 mm to obtain an unstretched product. At that time, as in Example 2, the draft rates were set to 5, 10, and 30, respectively.
I changed it twice and rolled it up. These unstretched products were stretched in n-decane heated to 130°C,
Stretched products with various stretching ratios were obtained. This was evaluated in the same manner as in Example 1, and the results are shown in Table 2. Comparative Example 1 10 g of the same polyethylene as in Example 2 and 190 g of paraffin wax (melting point 52-54°C, molecular weight 350) were placed in a container at the same time, and after melting the paraffin wax, the mixture was rapidly heated to 200°C while stirring. , stirring was continued while maintaining the temperature. However, even after 20 minutes have passed after reaching the set temperature,
It remained separated into two phases: a molten mass of ultra-high molecular weight polyethylene and a solution diluted from a predetermined concentration, and was extremely non-uniform. After that, stirring was continued for an additional 60 minutes, but a uniform melt could not be obtained. This melt is supplied to a single screw extruder set at 180℃ and extruded.
spun. However, the strand was extremely brittle and could not be wound continuously. Comparative Example 2 Using the same polyethylene as in Example 1, it was weighed so that the final concentration was 5% by weight, and twice the amount of decalin was added to the weight of the ultra-high molecular weight polyethylene at room temperature. 0.2% di-tert-butyl para-cresol based on the weight of the polymer was added and stirred to thoroughly wet the polyethylene particles. On the other hand, a predetermined amount of decalin was heated in another container until it boiled, and the heated decalin was quickly poured into a container containing polyethylene particles that had been wetted with decalin while stirring. The polyethylene absorbed the hot decalin and swelled without association, and after standing for 5 minutes, a viscous homogeneous solution was obtained. Add this solution in advance
Extruded into water using a spinning tube heated to 150℃,
A gel-like fiber containing a large amount of decalin was obtained. However, during spinning, a considerable amount of decalin oozed out onto the cooling tank and winding bobbin, making it impossible to wind the fiber by applying a draft. After extracting decalin from the gel using n-hexane and drying, the inlet temperature was 120°C.
℃ and a heating cylinder set at an outlet temperature of 135°C to obtain a stretched product. The obtained stretched product was evaluated in the same manner as in Example 1, and the results are shown in Table 2. In addition, as in Example 1, in order to evaluate the quality variation of the unstretched material,
A 300 m long undrawn yarn was wound around a mm bobbin and left in water for 2 days. From the wound unstretched material, select three points: the outermost layer of the bobbin, the middle layer, and the innermost layer in contact with the bobbin, extract decalin using n-hexane, then dry and stretch at the same temperature as before. The performance of the obtained stretched product was evaluated. The results are shown in Table 2. These results show that there are considerable differences in the draw ratio and performance after stretching of the undrawn material wound around the bobbin, and that the wet undrawn material fuses with each other during stretching. , often had to interrupt the stretching. Comparative Example 3 Using the same ultra-high molecular weight polyethylene as in Example 1, this ultra-high molecular weight polyethylene and paraffin wax (melting point 42-44°C, molecular weight 300) were mixed at 20:
The mixture was mixed using a Henschel mixer at a mixing ratio of 80° C., and then supplied to a screw type single screw extruder set at 200° C. for melt kneading. Then, it was extruded into water through a die with a spinneret diameter of 2 mm to obtain an unstretched product. At that time, the draft ratio was changed to 5, 10, and 30 times, respectively. These unstretched products were stretched in n-decane heated to 130°C to obtain stretched products.
This was evaluated in the same manner as in Example 1, and the results are shown in Table 3. If carried out without using the method of preparing a melt of paraffin wax and ultra-high molecular weight polyethylene of the present invention, stretching breakage often occurs during long-term operation, and the final strength achieved is also lower than that of the present invention because the stretching ratio is low. It can be seen that this is lower than in the example. Comparative Example 4 Comparative Example 3 except that the mixing ratio of ultra-high molecular weight polyethylene and paraffin wax was changed to 8:92
Similarly, when the mixture was mixed using a Henschel mixer and then melt-kneaded using a screw-type single-screw extruder, there was a lot of gel-like material containing unmelted polyethylene, and it was difficult to remove the melt continuously. . An attempt was made to draw a part of the yarn in the same manner as in Comparative Example 3, but the undrawn yarn was brittle and could not be drawn continuously. Comparative Example 5 (Determination of Low Wetting Temperature) Using the ultra-high molecular weight polyethylene used in Example 1, 10 g of each and 100 g of each of the paraffin waxes used in Example 1 were mixed, and 80, 90, 100 ,
I attempted to determine the amount of paraffin wax that had penetrated into ultra-high molecular weight polyethylene by stirring for 15 minutes at each treatment temperature of 110, 120, and 130°C, but at 130°C.
Even under these conditions, the ultra-high molecular weight polyethylene powder hardly swelled and only melted on its surface, making it impossible to determine the low-temperature wetting temperature. (Preparation of ultra-high molecular weight polyethylene melt) After putting 8 g of the ultra-high molecular weight polyethylene and 92 g of paraffin wax into a glass beaker, the mixture was heated to a temperature of 130°C, which is lower than the melting point of the polyethylene, and stirred for about 30 minutes. As I continued to do this, I ended up in what is known as a "stank" state. Subsequently, the temperature was raised to 200°C and stirring was continued, but a homogeneous solution was not obtained, and a dilute melt portion and a mass of molten polyethylene were observed. An attempt was made to extrude this melt in the same manner as in Example 1, but it broke into pieces and could not be extruded continuously. Comparative Example 6 According to the method described in the Examples of JP-A No. 59-232123, the same polyethylene as in Example 1 was used to measure the low-temperature wet treatment temperature when decalin was used as a solvent. The temperature was 108℃. The same polyethylene as in Example 1 was mixed with decalin so that the final solution concentration was 5% by weight, and the temperature of the system was heated to 110°C while stirring, and at that temperature.
The polyethylene powder was kept moist for 10 minutes. After confirming that the viscosity of the entire system had increased, the temperature was further raised to 160°C and stirring was continued, resulting in a viscous homogeneous solution. This solution was extruded into water using a spinning tube preheated to 150°C to obtain gel-like fibers containing a large amount of decalin. However, during spinning, a considerable amount of decalin oozed out onto the cooling tank and the winding bobbin, making it impossible to wind it by applying a draft. Thereafter, a stretched product was obtained in the same manner as in Comparative Example 2. When this was evaluated in the same manner as in Example 1, the same phenomenon of interruption of stretching as described in Comparative Example 2 occurred, and the same poor physical properties as shown in Table 2 were obtained.

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[Table] Example 4 Using the same polyethylene as in Example 1, it was weighed in advance so that the final polymer concentration was 12 wt%.
After adding n-decane in an amount equal to the weight of the polyethylene, the mixture was heated to 100°C and thoroughly stirred. A slurry containing polyethylene in which the polyethylene powder was slightly swollen was obtained. Meanwhile, in a container equipped with a stirring device, add a predetermined amount of paraffin wax (melting point 42-44℃, molecular weight 300) to 200℃.
The mixture was heated and melted at ℃ and stirred, and the polyethylene slurry was quickly poured into the mixture. Note that 0.2% by weight of di-tertiary butyl para-cresol was added to the paraffin wax in advance. After a while, a uniform paraffin wax melt of ultra-high molecular weight polyethylene was obtained. This melt was extruded from a spinning tube at a temperature of 200°C, and the winding speed was changed to 1, 5, and 10 times the spinneret exit speed. The thread could be wound stably without breaking. After extracting the paraffin wax from the obtained undrawn yarn using n-hexane, it was drawn using a heating cylinder set at an inlet temperature of 120°C and an outlet temperature of 135°C. The obtained stretched product was evaluated in the same manner as in Example 1, and the results are shown in Table 4.

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Claims (1)

[Claims] 1 Paraffin wax that is solid at room temperature that has been heated and melted in advance, and ultra-high molecular weight polyethylene with a weight average molecular weight of 1 x 10 ⁶ or more that has been wetted or dispersed with a liquid organic compound that is compatible with the paraffin wax. , a paraffin wax melt obtained by mixing paraffin wax and ultra-high molecular weight polyethylene in a weight ratio of 97:3 to 70:30 is extruded, and at least 1
A method for producing a stretched ultra-high molecular weight polyethylene product, which comprises cooling and fixing after drafting as described above, and stretching at a stretching temperature of 60 to 140°C and a stretching ratio of at least 8 times.