JPS61282417A - Polyethylene multifilament yarn - Google Patents

Abstract

PURPOSE:To obtain the titled yarns having a high strength and elastic modulus and knot strength, by dry jet-wet spinning a solution of polyethylene having a sufficiently high molecular weight, coagulating the solution, extracting the solvent, drying the resultant filaments while vibrating the filaments with a turbulent air stream, heat-treating the resultant filament yarn and drawing the filament yarn under specific conditions. CONSTITUTION:Polyethylene having >=700,000, preferably >=2000,000 weight- average molecular weight is dissolved in a solvent, and the resultant solution in 1-8wt% concentration is dry jet-wet spun and coagulated. After extracting the solvent, the filaments are dried while blowing a turbulent air stream thereon, heat-treated at 80-110 deg.C under tension and drawn at a draw ratio to give >1.5-<=3.0 denier filament fineness and >=50g/d filament strength. Thus, the a aimed multifilament yarns >=1,500g/denier elastic modulus, >=0.013 height in gamma dispersion peak of tan delta, >=1,000g/denier value of dynamic elastic modulus (E') at 100 deg.C, >=15g/denier knot strength and no recongnized reflection showing a long period on the meridian line in the small-angle X-ray scattering pattern and gluing between filaments.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a polyethylene multifilament yarn having high strength, high elastic modulus, and high knot strength. The present invention relates to a polyethylene μ6 fiber yarn pipe having the following characteristics.

(Prior art) In recent years, a method for obtaining high-strength, high-modulus polyethylene fibers from ultra-high molecular weight polyethylene has been proposed in Japanese Patent Application Laid-open No. 5 [1-522 [1]
Publication No. 2 JP-A-55-10756, JP-A-56-
Publication No. 15408, JP 59-216912-216
It is described in Publication No. 914, etc.

These methods involve spinning a semi-dilute J solution of ultra-high molecular weight polyethylene, cooling it to once form a gel-like yarn, then drying or solvent extraction, drying to remove the solvent, and ultra-stretching. It is possible to produce m-fibers having higher strength and interconnectivity by simultaneously applying desolvation and ultra-stretching.

Due to its properties, the polyethylene fibers obtained in this way can be used for industrial fiber applications that require high strength and high elasticity, such as ropes, slings, ring rubber reinforcements, various resin reinforcements, and concrete reinforcements. I hope it will be useful.

However, the above-mentioned method of forming a single-gauge-like yarn has problems such as sticking between the single yarns during the drying process.
Not suitable for multi-fiber yarn production. That is, when the gel-like yarn is dried or when it is stretched while being dried, significant sticking occurs between the single yarns. The cause of adhesion between single yarns is not known in detail, but each single yarn spun from a solution and gelled by cooling is in a swollen state containing a large amount of solvent. Since they are in close contact with each other, it is thought that significant adhesion would occur if they were simply dried to remove the solvent. In fact, especially in the non-crystallized portion of the gelled single fibers, the solution is simply supercooled, and there is virtually no boundary between the % single fibers. In addition, rather than simply removing the solvent by drying the core, the solvent is first extracted using an extractant.

If a method of subsequent drying is used, the sticking between the single yarns can be alleviated somewhat, but it is still insufficient.

This inter-filament adhesion becomes more pronounced as the polymer concentration of the solution used for spinning becomes lower. In order to increase the strength and elastic modulus, it is necessary to use a polymer with a large molecular weight and spin a Wr solution with the lowest possible polymer concentration, so it is necessary to obtain a multi-fiber yarn with high mechanical properties. This single thread will become M for a long time.

The sticking between single yarns that occurs in this way leads to problems such as lowering the strength utilization rate during heating, lowering the strength of the yarn itself, and even causing the yarn to lack flexibility. Therefore, despite the expected usefulness mentioned above, there are many inconveniences in making full use of these custom-made textiles for industrial textile applications, and it may be extremely difficult to mass-produce them on an industrial scale. What is happening is compassion.

On the other hand, Example V of JP-A-56-15408 describes what seems to be a so-called dry spinning method, but this method does not provide very high strength and elastic modulus. Furthermore, dry spinning of high molecular weight polyethylene requires the use of a solvent with a relatively high boiling point, and a high amount of heat is required to evaporate the solvent. For example, processes that would be unimaginable in industrial production are used, such as blowing gas at a temperature higher than the boiling point of the solvent onto the discharged solution stream, or taking an extremely long distance until the yarn is almost completely dry. There is a point.

Further, although the elastic modulus of the polyethylene fibers obtained by these conventional methods reaches the theoretical value of about 8096 Y at maximum, the strength is considerably different from the theoretically calculated modulus. The theoretical value of strength varies depending on the researcher, but it is equivalent to 210 to 750 g/At (g/6 unit t), and 10
Only about 30% of the 96% has been achieved. Therefore, there is still room for modifying polyethylene fibers.

Furthermore, in industrial fiber applications that require knots, if the knot strength is low, the strength of the fiber cannot be fully utilized, but it is difficult to increase the knot strength with general high-strength, high-modulus fibers. For example, aromatic polyamide fiber has a strength of 2
Although it is as high as 2 g/i, the knot strength is only 6 g/6, and carbon fiber (strength 29 g/11) cannot even form knots.

(The industrial fiber material that the invention seeks to solve is required to be light, strong, and have a high modulus of elasticity in order to support the energy saving and high functionality of products that use it. In some cases, high knot strength is also an essential characteristic.As mentioned above, there is still a lot of room for improvement in this kind of conventional high-strength, high-modulus fibers. An object of the present invention is to provide a multifilament yarn with high strength and elasticity, preferably high knot strength, which is more suitable as an industrial textile material, and which is substantially free from monofilament sticking.

(Means and effects for solving the problems) This problem of the present invention is as follows.

(1) Made of polyethylene with a weight-average molecular weight of 700,000 or more, single fibers exceeding 1.5 d and 501 m or less, 50 g
Single yarn strength of /σ or more.

It has an elastic modulus of +500876 or more, and no long-period reflection is observed in the small-angle X-ray scattering image, and the height of the r dispersion peak of tan δ in the dynamic viscoelasticity measurement E is α013. and the dynamic elastic modulus E' is 100℃
A polyethylene multifilament yarn having a value of jooOH/d or more and substantially free from inter-filament sticking.

(2) The polyethylene multifilament yarn according to item 1 above, which has a knot strength of 15 g/d or more, (3) A single yarn strength of 60 g/6 or more, 1800 g.
/ The polyethylene multifilament yarn according to the above item 1 or 2, which has an elastic modulus of 6 or more and a γ dispersion peak height of % tan δ of 101 or less; (4) a weight average molecular weight of 2 million or more; Items 1 to 3 above also include polyethylene multifilament yarns.

(s) Single yarn strength of 70g/d or more, 2000g/A
The polyethylene multifilament yarn according to the above items 1 to 4 having an elastic modulus of the above, or (6) the wet-dry spun polyethylene multifilament yarn according to the above items 1 to 5.

This was achieved using a new polyethylene multifilament yarn.

The novel polyethylene multifilament yarn of the present invention is substantially composed of crystals with fully extended molecular chains, and the slightly contained amorphous portion is also highly oriented, so there is little structural difference from the crystalline portion, and the period is long in the fiber axis direction. It has no structure. In fibers having a long period structure, reflections indicating a long period in the meridian direction are observed in small-angle X-ray scattering images, but this reflection is not observed in the vA fibers of the present invention.

Further, the height of the r-dispersion peak of tan δ (peak around −130° C.) in dynamic viscoelasticity measurement reflects the quantitative proportion of the amorphous portion, and the lower this peak is, the less the amorphous portion is.

On the other hand, the dynamic elastic modulus Σ' decreases as the temperature increases from low to high, but it crystallizes! and the higher the degree of orientation, i.e. -M
The higher the integrity of the k structure, the higher the value maintained until close to the melting point. The fiber of the present invention has r fraction peak heat of tan δ
Not only does it exhibit a significantly low value of 0.013 or less, but it also maintains a high E' value of 1008 g/d or more even at 100°C. Note that the dynamic viscoelasticity was measured under the following conditions.

Equipment Toyo Bowdoin Co., Ltd. CDI/- [Model frequency 1101! The polyethylene multifilament yarn of the present invention has a heating rate of 3°C/min as described above.
If the structural integrity is high, and therefore the single yarn strength is 50 g/d or more, the elastic modulus is 1500 H/d or more, and the height of the tan δ γ dispersion peak is 101 or less, the single yarn is 606/d or more. It is a completely new fiber that has strength, a bullet modulus of +800 g/'d or more, and excellent fibrillation properties.

Further, although the relationship with the structure is not clear, the preferred polyethylene multifilament yarn of the present invention surprisingly has a knot strength of 15 g/d or more, and thus has high strength and high elastic modulus. However, fibers with high knot strength are extremely specific because both properties are generally in a trade-off relationship.

The novel polyethylene multifilament yarn according to the present invention is provided, for example, by the following novel manufacturing method.

Polyethylene with a weight average molecular weight of 700,000 or more is dissolved in a solvent, and a bath solution containing 1 to 8% by weight of tallyethylene is prepared as Tl.
41i. This solution is extruded into a coagulation bath through a nozzle having a plurality of holes through an atmosphere layer of air or an inert gas to form a coagulated thread, and then the solvent is extracted. Next, the coagulated and extracted threads are dried while being blown with turbulent gas and vibrated to prevent the single threads from becoming stuck together. Furthermore, dry the yarn at a temperature of 80°C to 110°C. After heat treatment, 1
At 35°C to 145°C, the single yarn fineness exceeds t5α and becomes 5 Oa, and the single yarn strength is at least 50 g/different t.
Stretch at a sufficient magnification.

The characteristics of this new manufacturing method are that wet-dry spinning is used, the coagulated and extracted yarn is vibrated with turbulence and dried in a manner that prevents single yarns from coming into close contact with each other, and that the fibers are heated to a specific temperature range before drawing. This involves applying tension heat treatment.

The polyethylene multifilament yarn obtained by this method is substantially 1; there is no thread 511 between the single yarns, and the single yarn wA
The fiber has a single fiber strength of 50 g/d or more, an elastic modulus of 1500 E/eL or more, and has a reflection that shows a long period on the meridian in a small-angle X-ray scattering image. It is not recognized, and the height of the r dispersion peak of tan δ in dynamic viscoelasticity measurement is less than 013,
Dynamic elastic modulus]! 8/ My weight at 100℃ is 1000g/
15 g/d or more, and the nodule strength is 15 g/d or more.

The details of the polyethylene multifilament yarn of the present invention and the method for producing the same are as follows.

The polyethylene used to obtain the polyethylene multifilament yarn of the present invention must have a high molecular weight. That is, the weight average molecular weight is at least 7.
00,000, preferably at least 2 million. When a polymer with a low molecular weight is used, there are many defects such as molecular chain ends inside the obtained fiber, and the deformation during high-magnification stretching is mainly caused by slipping between molecular chains, so stretching does not work effectively to improve strength. .

Polyethylene here refers to a small amount of, for example, 10 mo/I
/96 or less, such as propylene, butylene, pentene, hexene, 4-methoxypentene, etc., or one or more vinylμ monomers that can be copolymerized with ethylene. It's okay.

In addition, the solvent for the polyethylene mentioned above is one that satisfies the following conditions: it has good solubility, it is easily pumped out in the subsequent coagulation process, and its boiling point is higher than that at the time of dissolution or spinning, such as decalin and / or white kerosene is preferably used.

Borinylene in polyethylene solution! The higher the molecular weight of the polyethylene, the lower the 11 degree condition is selected, and the appropriate solution viscosity is selected from the viewpoints of uniformity of dissolution, discharge stability during spinning, threadability, and thread refining during drawing. The concentration is selected so that However, if the polyethylene concentration is less than 1% by weight, it is not preferable because not only is productivity poor, but the coagulated yarn is soft and the yarn running becomes unstable, susceptible to external disturbances, and lacks uniformity. Also, the higher the polyethylene content, the higher the productivity.

If it exceeds 8% by weight, the viscosity of the solution increases due to the entanglement of polyethylene molecular chains in the solution, resulting in an inappropriate concentration range [which leads to poor spinnability during spinning]. Not only does it decrease, but the stretching ratio does not increase sufficiently during stretching after solvent removal, and only a low cage can be obtained, which is undesirable.Therefore, polyethylene RH
A polyethylene concentration of 1 to 8% by weight is suitable.

In order to improve strength and elastic modulus, it is necessary to increase the draw ratio, and it is desirable to spin from a dilute solution using polyethylene with a higher molecular weight. Therefore, using polyethylene with a weight average molecular weight of 2 million or more, It is more preferable to spin from a bath solution with a concentration of 1 to 5% by weight, and it is even more preferable to use polyethylene having a weight average molecular weight of 5 million or more and to spin from a solution with a polyethylene concentration of 2 to 35I5. be.

It is preferable that the melting temperature of polyethylene at the time of solution dissolution and the degree of solution fa during spinning are approximately the same, and vary depending on the molecular weight of the polyethylene, approximately 150 to 200'Q.
Appropriate temperature conditions are set within this range. For example, when polyethylene having a weight average molecular weight of 2 million is used and spinning is performed from a solution having a polyethylene concentration of 596, a temperature of about 170°C is appropriate.

The solution is forced through a multi-hole nozzle through a layer of air or an inert gas atmosphere into the coagulation bath. There is no particular limit to the distance through which this gas atmosphere passes, but
505 m is appropriate; if it greatly exceeds 50 m, it becomes difficult for the fibrous solution extruded from the nozzle to run stably.
This is not preferable because a slight yarn wobbling causes problems such as single yarn sticking in this gas atmosphere, resulting in unsteadiness.

Although a small amount of solvent may evaporate from the extruded fibrous solution in this gas atmosphere, most of the solvent is extracted and removed in the coagulation bath and subsequent extraction bath.

In the present invention, the coagulant used in the coagulation bath and extraction bath is one that does not dissolve or swell the polyethylene at the coagulation temperature in order to prevent single filament sticking.
Also, one is selected that has good compatibility with the solvent and is continuous at room temperature. for example.

Acetones, methanol, ethanol, etc. 5/7:
Examples include I-/l/ and the like. Japanese Patent Publication No. 58-5228
In the method described in the above publication, since a polyethylene solvent is used for extraction, it is thought that the sticking between single fibers becomes even more severe. The temperature of the coagulation bath and extraction bath varies depending on the coagulation ability and boiling point of the coagulant used, but is usually 0 to 4.
A range of 0°C is suitable.

The yarn coagulated in the coagulation bath is then sent to an extraction bath, where the remaining solvent is extracted and removed, and then dried. Alternatively, the extractant may be replaced with a second extractant and then dried. For example, replacing a flammable first extractant with a second, less flammable extractant.

In drying the coagulated yarn I, the yarn is dried by blowing turbulent gas and vibrating it. In the turbulent flow, each single yarn is in a disordered state and is dried without being in close contact with each other (therefore, it is possible to avoid sticking between single yarns.

This is how you use a solution of polymers! If 1 degree is low,
The solution should not be gelatinized (direct coagulation bath is thick and the fiber surface should be completely coagulated before the single fibers are bundled), and when drying the coagulated yarn, the single fibers should not be in close contact with each other. By doing so, it is possible to obtain a multifilament yarn that is substantially free from inter-thread adhesion.

The above-mentioned spinning method, ie, the spinning method in which a polymer solution is extruded into a coagulation bath through a nozzle or a gas atmosphere, is itself known as the so-called dry spinning method. However, using such high molecular weight polyethylene, high strength and high elasticity
The ability to obtain 4A fibers was previously unknown.

In the spinning chamber of this method, even if no spinning draft is provided, when the solution coagulates and forms solidified threads (this tends to shrink, stress is applied to the threads. The fibrous 1g solution and the coagulating thread are in a tension state and form a stable thread path.Moreover, the molecular chains in the solution are slightly oriented in the I!i fiber axis direction and crystallized, so that the fiber axis direction [ The C-axis orientation of the humeral crystals also progresses.

This orientation is considered to be an advantageous direction for disentangling the molecular chains from the Ramep crystal, and is therefore effective in stretching the molecular chains in the subsequent stretching step to grow stretched-chain crystals.

JP-A-58-5228, JP-A-55-10756
No. 56-15409, Japanese Patent Application Laid-Open No. 1983-15409
216912 to 216914, etc. In the method described in this paper, in which a gel-like yarn is formed once, there is no tension during coagulation, and the yarn path tends to become unstable. Also, since the gel contains a considerable amount of solvent, molecules of It is thought that the orientation of the chains is easily relaxed and the subsequent stretching stretches the molecular chains and causes the growth of fully extended chain crystals, which is not effective.

In addition, with this method, if the soft gel comes into contact with the guide or low two, it may be damaged, and the solvent may ooze out, causing the yarn to become thick.
There is also the problem that it is easily susceptible to many disturbances such as

Furthermore, this method is unsuitable for producing multifilament yarns, as single yarn breakage occurs as described above.

Compared to this method, the method for obtaining multifilament yarns of the present invention does not have such drawbacks and can achieve high strength at relatively low draw ratios.

After coagulation and extraction, the dried yarn is then heated to 60°C to 11°C.
A tension heat treatment is performed at a temperature of 0°C.

In this heat treatment temperature range, polyethylene tends to crystallize and lamellar crystals grow, but when the molecular chains of the amorphous part are incorporated into the crystal, some of the entanglements are disentangled and the number of lamellar crystals is reduced. Seem. By reducing the number of molecular chain entanglements through heat treatment of the dry yarn in this manner, the molecular chains are more easily stretched, forming fully extended chain crystals.

In the next step, the tension heat-treated yarn is heated to 135℃~1
It is drawn repeatedly at 45°C to a sufficient magnification to give a single filament strength of at least 50.5/d. In this case, the stretching is preferably performed in three or more stages.

More preferably, it is carried out in multiple stages of four or more stages. In addition, the drawing speed in the first stage of stretching (up to approximately 20 times in terms of magnification) may be high, but in the second stage of stretching, it is preferable to repeatedly draw at a relatively low speed (yarn feeding speed of 1 m7 minutes or less). The area should be as wide as possible; for example, when stretching is performed using a hot plate, it is preferable to use a hot plate with a diameter of 1 m or more.

In this manner, the molecular chains are loosened from the lamellar crystals and recrystallized in the fully stretched state by gradually stretching at a lower stretching speed and over a wider area as the latter stages progress.

It is necessary to determine each spinning condition so that the fiber after drawing has a single fiber fineness of more than L5a and less than 5OcL, preferably more than 1.54 and less than λOa.

In general, when the spinning conditions are the same, the smaller the fineness, the higher the strength. However, if the fineness is too small, it may cause handling problems such as fuzzing when processed into the final product, or the product may fuzz during use. It is easily damaged, resulting in significant damage to the appearance.

The yarn of the present invention achieves a single yarn strength of 506/d or more and an elastic modulus of 15006/i within the above-mentioned fineness range, and is easy to handle.

Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

The yarn physical properties shown below were measured under the following conditions.

Yarn sang/l/: Single yarn trial length: 250 Tensile speed H3O0a, 7 minutes Atmosphere: 20°C, 65% relative humidity (5j! Example) Examples 1 to 3 Straight yarn with a weight average molecular weight of 3 million A 50% by weight solution was prepared by dissolving high density polyethylene in kerosene at a temperature of 190°C. This solution was heated at 180°C with a pore size of 1 m and a hole ek of 20
After the air atmosphere was passed through the nozzle for a distance of 5 mm, it was extruded into a coagulation bath consisting of 7 tons of 205!5 kerosene at 20°C and coagulated. Noz μ Kamo Satoshi discharge amount -
was 900 C/min, and the coagulated yarn was drawn off at 7.5 m/min.

1. The yarn was then passed through an extraction bath of 20 DEG C. to extract the remaining kerosene in the yarn, and dried under turbulent air at room temperature while being vibrated. After that, the yarn is 90
After heat treatment for a fixed length at 140° C., the film was continuously stretched in one stage at 140° C. and then wound up with a winder.

The obtained yarn had no stagnation due to Tobo slow single yarn processing and had good fibrillation properties. Next, the wound yarn was fed at a speed of j m/min and further drawn in two stages. Table 1 shows the drawing conditions and the properties of the obtained drawn yarn. Incidentally, no sticking occurred between the single yarns even in the drawing process.

Table 1 Note) From the second stage onwards, continuous stretching was carried out.Example 4 The same solution as in Examples 1 and 5 was used and the same spinning was carried out, but the nozzle μ had a hole diameter of 1, number of holes 10, and ε The output rate was 60 machin/min. The subsequent extraction, drying, and constant length heat treatment are similar, but! P! After processing, it was rolled up with wine goo. The obtained threads had no sudden sticking between the threads and had good fibrillation properties. Next, the wound yarn was fed at a low speed and repeatedly drawn. In this case as well, no sticking occurred between the single yarns during the drawing process.The drawing conditions and the properties of the obtained drawn yarn are as follows.

Yarn feeding speed (m/min) Drawing temperature ('C) Drawing ratio 1st stage 5 155 14 2nd stage Yu2142 50t7gs stage (L5 145 10 Drawing yarn characteristics Vermilion fineness 1.8 Electrical strength 75
g/6° elongation
Percent modulus of elasticity 2230 g/Nodule strength 20 g/Length
Period W4 was not measured and 100℃ IC of
E' 1800 i/dT peak height α006 Comparative Example 1 Linear high-density polyethylene having a weight average molecular weight of 5 million was dissolved in kerosene at a temperature of 19Q°C.

A 10% by weight solution was prepared. This solution was passed through an air atmosphere for a distance of 5 volts from a nozzle with a hole diameter of 1 mm and 20 holes at 180°C, and then extruded into water at 20°C, cooled, and gelled to form a gel-like thread. . The total discharge amount from the nozzle M was 90a-7 minutes, and the gel-like yarn was 7. ．． 5I!
I picked it up in 17 minutes.

The μ-shaped yarn was then passed through an extraction bath of acetone at 20° C. to extract the kerosene remaining in the yarn, and each single yarn was dried in a bundle and wound with a winder.

This yarn was drawn in two stages, and the 1-strength was 436/d and the 1-elastic modulus was 1270 g/d. In addition, the γ dispersion peak height of tan δ is α019, and E′ at 100°C
was 650 g/d. Note that the stretching conditions are as follows.

Yarn feeding speed (m/min) Stretching temperature C℃) Stretching ratio 1st stage 5 155 12 2nd stage
12 145 4.2 The obtained yarn t; had many stictions between single yarns and could not be defibrated neatly.

Furthermore, when the decalin in the gelatinous filaments was dried at 60°C using the same method of spinning except for the extraction step, the single filaments were stuck together significantly and could not be defibrated at all.

Comparative Example 2 Linear high-density polyethylene with a weight average molecular weight of 500,000 was dissolved in decalin at a temperature of 170°C, and a 55% by weight solution was dissolved in v4! I did it. This /8 liquid was spun in the same manner as in Examples 1 to 3, and the obtained yarn was drawn under the following conditions.

Yarn feeding speed (m/min) Stretching temperature ('C) Stretching ratio 1st stage 7.5 140 + 2 2nd stage
Row (124422,5 5th row α2 145 2.0 The single yarn fineness of the drawn yarn was 2.24 d, and the strength and elastic modulus were each as low as 30 g/d% and 870 g/4.

(Effects of the present invention) As explained above, the polyethylene multifilament yarn of the present invention has extremely high strength and does not have a tensile strength utilization rate of 9 or less during aging.

It is extremely useful as a 1a fiber material for various industries.

Claims (6)

[Claims] (1) Made of polyethylene with a weight average molecular weight of 700,000 or more, single yarn has a fineness of more than 1.5 d and less than 3.0 d, 50 g
/d or more, a single fiber strength of 1500 g/d or more, and no long-period reflections observed in small-angle X-ray scattering images, and with a tan δ γ dispersion peak in dynamic viscoelasticity measurements. A polyethylene multifilament yarn having a height of 0.013 or less, a dynamic elastic modulus E' at 100° C. of 1000 g/d or more, and substantially free from inter-filament sticking. (2) The polyethylene multifilament yarn according to claim 1, which has a knot strength of 15 g/d or more. (3) It has a single yarn strength of 60 g/d or more, an elastic modulus of 1800 g/d or more, and a tan δ γ dispersion peak height of 0.
01 or less, the polyethylene multifilament yarn according to claim 1 or 2. (4) The polyethylene multifilament yarn according to claims 1 to 3, which has a weight average molecular weight of 2 million or more. (5) The polyethylene multifilament yarn according to claims 1 to 4, which has a single yarn strength of 70 g/d or more and an elastic modulus of 2000 g/d or more. (6) Wet-dry spun polyethylene multifilament yarn according to claims 1 to 5.