JP2001279519A - System for precisely measuring/controlling neighborhood of position of drawing point of synthetic yarn by infrared ray radiation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a synthetic yarn of uniform structure by precisely measuring a yarn diameter, a yarn speed, a yarn temperature, a molecular orientation, etc., or their fluctuations with time in the vicinity of a drawing point and more precisely controlling the position of the drawing point in a process for melt spinning or drawing of synthetic yarn or monofilament. SOLUTION: A yarn is rapidly and uniformly heated and drawn by irradiating the traveling yarn with a powerful infrared flux. The position of the drawing point is precisely fixed, the measured result is fed back to a laser output to control the position of the drawing point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measurement system which enables a precise measurement near the drawing point by irradiating a strong infrared light beam to a synthetic fiber yarn, and a fiber structure / physical property utilizing the measurement result. Related to a system for precisely controlling the pressure.

[0002]

2. Description of the Related Art In the process of producing synthetic fibers or monofilaments by spinning and drawing, yarn diameter, yarn speed, yarn temperature, molecular orientation, etc., or elongational viscosity, strain rate, and crystallization rate derived indirectly from these. It is fundamentally important to accurately measure such information and control it optimally. However, in the high-speed melt-spinning process or secondary stretching process that causes a so-called neck-like deformation on the spinning line, the structure formation is concentrated near the very short stretching point, and the position of this stretching point fluctuates. Control was difficult. Particularly in the high-speed spinning / drawing process, the fluctuation of the drawing point tends to be large, but the structure formation itself becomes faster, so that high-speed production while ensuring the uniformity of the product,
It was easy to be difficult.

Conventionally, in the process of producing synthetic polymer fibers, the heating of the fibers has been controlled directly by a contact heater or indirectly by controlling the ambient temperature in a heating zone by a non-contact heater. As the atmosphere in the heating zone,
Examples include heated air and steam. In these methods, heat transfer is mainly performed by heat transfer through the fiber surface, so that the efficiency of heat transfer is low and rapid heating is difficult. In addition, since the heat transfer passes through the fiber surface, uniform heating is generally difficult. Particularly, when the ambient temperature of the heating zone is set to a high temperature for the purpose of rapid heating, a remarkable temperature difference occurs in the fiber cross-section, resulting in improper heating. It tends to cause uniform deformation and non-uniform structure.

[0004] In particular, the fiber drawing step is a step in which a fiber having a low molecular orientation and a low crystallinity forms a so-called "fiber structure" having a high molecular orientation and a high crystallinity due to large deformation of the polymer. Because of the presence of a flexible element, the position of the deformation point (hereinafter referred to as “stretch point”) was likely to be unstable. A major cause of this instability is the temperature distribution in the fiber axial direction and the fiber radial direction. That is, the heating rate in the fiber axis direction increases as the amount of heat transfer to the fiber surface increases, but in this case, the temperature distribution of the fiber in the radial direction generally also increases. For this reason, high-speed heating in the fiber axis direction and uniform heating in the fiber radial direction have not been compatible with each other until now.
It has been difficult to accurately measure information such as the yarn diameter, yarn speed, yarn temperature, and molecular orientation of a yarn running at high speed near the drawing point. Therefore, it is also difficult to precisely control the fiber structure by feeding back the measurement results.

[0005] The step of stretching the yarn between the first take-up roller and the second take-up roller, the yarn melt-spun from the spinneret is once cooled and solidified, and then the first take-up roller and the second take-up roller are cooled. In a direct spinning / drawing step of drawing between, or a test synthetic fiber drawing apparatus assuming these, a pin heated to a high temperature is installed between a first take-up roller and a second “take-up roller, and drawing is performed on this pin. In many cases, so-called “pin drawing” is performed to fix the drawing point position near the pin surface, but in the case of pin drawing, heating of the fiber depends on heat transfer from the pin surface to the fiber surface. Therefore, the heat transfer from the fiber surface to the inside of the fiber depends on heat conduction, so that the temperature in the cross section inside the fiber is likely to be non-uniform and uniform drawing is difficult. Yarn diameter, yarn speed, yarn temperature and molecular orientation or the like in this order draw point near also tends to be uneven, unstable, precise measurement and control is also difficult.

Further, the yarn is taken up by a first take-up roller and a second take-up roller.
A step of drawing between the take-up rollers, a direct spinning / drawing step of once cooling and solidifying the yarn melt-spun from the spinneret and then drawing it between the first take-up roller and the second take-up roller, or In a supposed experimental synthetic fiber drawing apparatus, a drawing method in which the first take-up roller is heated, and the heated yarn is wound around the first take-up roller and drawn by the second take-up roller to be wound is usually referred to as "roller drawing". In this roller stretching step, the position where the fiber is actually stretched (stretching point position) is near the peeling point from the first take-off roller. In the roller drawing step, the contact time with the fiber surface of the roller can be increased by winding the yarn around the roller several to several tens of times, and sufficient tension can be obtained with a small surface friction coefficient, and Since sufficient time can be secured for heating by heat transfer from the surface, it is easy to cope with speeding up of the stretching process. However, keeping the glass transition temperature near the glass transition temperature longer than necessary before the drawing point unnecessarily changes the fiber structure before drawing, which is not preferable. Therefore, the set temperature of the first take-off roller is higher than the drawing temperature of the fiber. The number of windings is set high, and the number of windings necessary and sufficient for the fiber temperature to reach a predetermined drawing temperature is selected. On the other hand, in the case of roller stretching, the stretching point is determined by the balance between the frictional force and the tension between the yarn and the roller surface, and the stretching is generally performed near the roller having a much larger diameter than the pin stretching. In addition, the vertical force applied from the yarn to the roller surface is small, and the drawing point is liable to fluctuate greatly under the influence of minute variations in yarn tension and minute changes in the contact state due to humidity and the like. Further, the heat transfer between the roller surface and the yarn fluctuates under the influence of the contact state and the surface state, and the fiber temperature and the heating history also fluctuate. Particularly when the film is drawn at a high speed, the fluctuation tends to be large, and it is difficult to precisely measure and control the yarn diameter, the yarn speed, the yarn temperature, the molecular orientation, and the like near the drawing point. In order to fix the position of the stretching point, there is also a method of increasing the heat transfer efficiency by spraying high-temperature steam or the like near the stretching point to suppress the fluctuation of the stretching point position (for example, US Patent No. 4,113,82).
1). Although this method has a certain effect in reducing the fluctuation range of the drawing point position, it is a method for increasing the speed of heat transfer to the fiber surface, and does not directly heat the inside of the fiber. Since there is no difference in the heat conduction speed inside the fiber, increasing the heat transfer speed means increasing the temperature distribution inside the fiber, and the yarn diameter, yarn speed, and yarn temperature near the drawing point.・ Not suitable for precise measurement and control of molecular orientation.

Further, a step of stretching the yarn between the first take-up roller and the second take-up roller, the yarn melt-spun from the spinneret is once cooled and solidified.
In a direct spinning / drawing step of drawing between the take-up roller and the second take-up roller, or in a test synthetic fiber drawing apparatus assuming these, water and oil etc. installed between the first take-up roller and the second take-up roller A method is also used in which the yarn is heated and stretched by heat transfer in a liquid heat medium or a gas heat medium such as air or water vapor. In the case of this drawing method, the position of the drawing point is determined by heat transfer to the yarn, heat medium temperature, tension, etc., and is easily affected by minute temperature unevenness of the heat medium, speed fluctuations, fluctuations in tension, etc. Further, it is difficult to fix the position of the stretching point.

A method of utilizing far-infrared heat radiation instead of heat transfer to uniformly heat a yarn is disclosed in Japanese Patent Laid-Open No. 4-28.
No. 1011 and Japanese Patent Application Laid-Open No. 5-132816 have demonstrated that there is a certain effect on uniform heating of the yarn. However, the only difference between these and the prior art is that the heat transfer method is changed from heat transfer to heat radiation, and a device of the same size as the conventional heating cylinder is used to heat the yarn. In addition, the same length as that used in the conventional drawing and heat treatment method is heated in the running direction of the yarn. Therefore, this method cannot be used for precisely fixing the position of the stretching point. Also, there is no mention of dynamically precisely controlling the stretching point.

Japanese Patent Application Laid-Open No. 61-75811 proposes a method of producing a polyester fiber having a high degree of orientation and a low specific gravity by irradiating an infrared ray with a carbon dioxide gas laser onto a yarn. In the present invention, the purpose of laser light irradiation is to produce a polyester fiber having a high degree of orientation and a low specific gravity, and there is no description or example of a method for precisely fixing a drawing point. In addition, there is no mention of dynamically precisely controlling the stretching point. It is generally known that laser irradiation light is used for stretching in the process of producing an inorganic fiber such as an optical waveguide. Conf. Hea
tMass Transfer, 2nd 225, (1
977). However, the drawing mechanism of these fibers does not mean that the fiber structure formation accompanied by structural changes such as molecular orientation and oriented crystallization, which is peculiar to the polymer used as the synthetic fiber material, occurs. It is fundamentally different from For example, in a high-speed melt-spinning step or a drawing step of a synthetic fiber material,
The main cause for the solidification of the drawn fiber is hardening of the material due to molecular orientation and oriented crystallization, but these contributions are very small in the drawing of the inorganic fiber.

[0010]

SUMMARY OF THE INVENTION The present inventors have been studying the production of synthetic fibers and monofilaments by infrared irradiation. By irradiating a running yarn with a strong infrared light flux, the synthetic fibers or monofilaments are produced. Since the monofilament is rapidly and uniformly heated and instantaneously stretched by an external force, the position of the drawing point can be precisely fixed, so that the yarn diameter, yarn speed, yarn temperature, molecular orientation, etc. near the drawing point can be adjusted. It has been found that precise measurement is possible and that the drawing point position can be precisely controlled by feeding back the yarn diameter, yarn speed, and yarn temperature profile fluctuation to the laser output.

[0011]

SUMMARY OF THE INVENTION The present invention comprises a step of drawing a yarn between a first take-up roller and a second take-up roller, and a step of drawing a yarn melt-spun from a spinneret by the take-up roller. Alternatively, a monofilament manufacturing process, a direct spinning / stretching process in which a yarn melt-spun from a spinneret is once cooled and solidified, and subsequently stretched between a first take-up roller and a second take-up roller, or a test assuming these. In the synthetic fiber drawing device, a strong infrared light beam is irradiated on the running synthetic fiber yarn or filament, the fiber is rapidly and uniformly heated and softened, and the drawing point is precisely fixed by deforming by external force. For accurately measuring the yarn diameter, yarn speed, yarn temperature, molecular orientation, elongational viscosity, strain rate, elastic modulus, and strain near the drawing point A.

Another aspect of the present invention is to precisely control the drawing point position by feeding back the measured fluctuations in the yarn diameter, yarn speed, and yarn temperature to the output of the irradiation laser. Since the strain rate profile and thermal history applied to the fiber can be controlled by precisely controlling the drawing point position, a synthetic fiber whose structure and physical properties are precisely controlled can be manufactured.

By preheating the yarn to a temperature lower than the softening temperature before irradiating the yarn with the infrared light beam, the output of the irradiated infrared light beam can be reduced. Examples of the method for preheating the yarn include a method of heating the first take-off roller, a method of using a liquid or gas heat medium, and a method of contacting a hot plate or the like. It is also possible to preheat the yarn by irradiating another light source or an infrared light beam having passed through an optical path. That is, after the yarn is preheated by the irradiation of the first infrared light beam, the position of the stretching point can be fixed near the second irradiation position by irradiating the yarn with the second infrared light beam.

Preferably, the running speed of the yarn is 0.1 m / sec or more, and the irradiation time of the infrared light beam to the yarn does not exceed 0.1 second. However, the irradiation time does not include the irradiation time of the infrared light beam for the residual heat described in the previous section. Further, for precise measurement, the fluctuation width of the drawing point position does not exceed 1 mm (typically 0.3 mm), or the length of the drawn yarn is 10 ms (typically 3 ms). It is desirable not to exceed the distance traveled within. For this purpose, the degree of molecular orientation of the synthetic fiber or monofilament before stretching is 0.1 or less, typically 0.01 or less, and the stretching ratio is 4 times or more, typically 5 times or more. desirable. Here, the fluctuation width of the extension point position means the width of the section in which the ratio of the time that the extension point position remains in the predetermined section reaches 90% or more. The infrared ray in the present invention refers to an electromagnetic wave having a wavelength range of 0.7 μm to 100 μm. Further, the yarn in the present invention refers to a single fiber, a fiber bundle, or a monofilament. Further, the irradiation range in the present invention refers to a range in which the intensity of the infrared light beam applied to the yarn is 1 / e ² or more as compared with the intensity at the position where the irradiation intensity is maximum in the yarn. . Here, e means the base of the natural logarithm. Further, in the step of stretching the yarn between the first take-up roller and the second take-up roller,
It means a portion where the deformation of the yarn mainly occurs, and is a section from a drawing start point where a main deformation starts to a drawing end point where the main drawing ends. In the present invention, a point at which the amount of true strain applied to the yarn reaches 20% of the total true strain applied in the drawing process is defined as a drawing start point, and this point represents a drawing point. That is, the stretching point in the present invention means the stretching starting point defined in this way.

By irradiating the yarn with a strong infrared light beam directly or via an optical system, a rapid and uniform heating can be achieved. Here, the optical system means a light-collecting lens, a reflecting mirror, or a waveguide such as an optical fiber. By adopting such a heating method, the heat energy can be concentrated on the minute space of the yarn as compared with the conventional method which mainly depends on heat transfer, and the position of the drawing point is precisely fixed by rapid and uniform heating. Is now possible,
It has become possible to construct a measurement system characterized by being able to accurately measure the yarn diameter, yarn speed, yarn temperature, molecular orientation, and the like, or their temporal variations near the drawing point.

As the infrared light source, a light source capable of generating energy enough to sufficiently heat the synthetic fiber yarn to a predetermined temperature in the irradiation range and emitting infrared light absorbed by the yarn is used. The amount of infrared energy is determined by the wavelength of infrared light, the efficiency of absorption of infrared light into the yarn, and the diameter of the yarn, yarn speed,
Depends on density and heat capacity. If the temperature rise due to infrared irradiation is expressed as ΔT, when it can be assumed that the running of the yarn is in a steady state, there is generally a relation of ΔT = Q / WC. Here, Q is the amount of energy absorbed by the yarn per unit time by irradiation, W is the mass flow rate of the yarn, and C is the specific heat of the yarn. Assuming that the infrared energy applied to the yarn per unit time is i, Q = Ki, where K is the absorptivity of the infrared energy by the yarn. As a typical condition, K =
0.6, yarn diameter 0.1 mm, yarn speed 5 m / s, specific heat 1.
Assuming 17 kJ / kg · K and a density of 1.32 Mg / m ³ , ΔT = 10i. That is, when the yarn is irradiated with 1 W of infrared light, the temperature of the yarn increases by 10 Kelvin. When heating a running yarn by infrared irradiation, the temperature distribution in the fiber cross section can be reduced by optimizing the optical system and the fiber diameter. For this reason, compared with the conventional heating method relying on the heat conduction from the fiber surface, the heating can be performed uniformly in a shorter time. Also, as is clear from the above, the heating amount (temperature increase amount)
It depends on the energy applied to the yarn, the running speed of the yarn, the energy absorption of the yarn, the diameter and the density of the yarn.
Therefore, by controlling these, it is possible to control the temperature profile of the yarn and indirectly control the diameter profile and the speed profile. In particular, since the position of the drawing point strongly depends on the position where the temperature of the yarn exceeds the softening point, the position of the drawing point is also likely to fluctuate depending on the temperature and diameter of the yarn. In order to minimize the fluctuation of the stretching point due to such a disturbance, it is desirable that the irradiation intensity change near the stretching point is large. That is, if the irradiation intensity is increased stepwise around the point where the yarn temperature reaches the softening temperature of the yarn, the drawing point can be fixed near this point. Such an intensity distribution can be created by using both an infrared light beam having a narrow irradiation range and an infrared light beam having a wide irradiation range. Further, even with a single light source, the stretching point can be fixed using the intensity profile. That is,
Since the rate of increase of the infrared light intensity applied to the yarn is the largest at the inflection point on the sending side of the irradiation intensity profile, the position at which the yarn reaches the softening temperature is set near this point. By setting the stretching conditions, the position of the stretching point can be best fixed. The control system of the present invention aims at minimizing the fluctuation of the drawing point position by dynamically controlling the intensity of the infrared light beam applied to the yarn. The basic control principle is that if the measurement point reflecting the yarn diameter or yarn speed indicates that the drawing point is moving downstream, or if the yarn temperature decreases, the infrared light flux Increase the strength of the
In the opposite case, the strength is reduced. In practice, there are response delays and system inertia described later, so it is desirable to select appropriate control systems and control parameters. The response speed of this control system is determined by electrical factors and mechanical factors. Of these, the electrical factor is
This is the time delay from the measurement of the yarn diameter, speed, and temperature until the intensity of the infrared light flux changes.
The time required for the operation system and the time required for controlling the infrared light source are included. The electrical delay time can be easily reduced to 1 ms or less by using an appropriate sensor and control circuit. On the other hand, as the mechanical factors, the running speed of the yarn and the inertia resulting therefrom are problematic. When irradiating a running yarn with an infrared light beam and stretching it, the temperature of the yarn rapidly rises within the infrared light irradiation range and exceeds the softening point, causing deformation and deformation.
Solidify. Therefore, the mechanical delay time is based on the time required from the start of the irradiation of the yarn with the infrared light to the start of the deformation at the drawing point.

As the infrared light source, a continuous spectrum light source using a high-temperature heating element and a coherent light source using laser oscillation can be used. It is preferable to use a coherent light source utilizing oscillation. This is mainly because the light source has high parallelism, so that it is easy to condense and form a parallel light beam, and that a large output is obtained. Light sources using laser oscillation include those using gas, solid, semiconductor, dye, excimer, and free electrons as emission sources. Among these, as a laser light source having an oscillation wavelength in the infrared region and obtaining a large output, an oscillation wavelength of 9 to 12 using a carbon dioxide gas as an emission source.
μm, and an emission wavelength of 0.9 to 1.2 μm using yttrium aluminum garnet (3Y ₂ O ₃ .5Al ₂ O ₃ ) to which a trace amount of Nd ³⁺ is added. Among these, a laser light source having an oscillation wavelength of 9 to 12 μm using carbon dioxide gas as an emission source has a high infrared energy absorption efficiency because many synthetic fiber materials are in a wavelength band in which strong absorption is performed. It is valid. In addition, this light source is preferable because it can maintain inexpensive and stable performance as compared with the output. This light source is manufactured in the form of a few tens of watts even in a sealed low power type, and several hundred watts to more than 1 kilowatt in a high power type. Can be. As the oscillation type of the laser oscillation, continuous oscillation is preferable. However, even if the oscillation is not continuous oscillation, oscillation may be performed at a sufficiently high frequency with respect to the running speed of the yarn. For example, if the running speed of the yarn is 50 m per second and the length of the heating region in the running direction is 1 mm, oscillating at a frequency of 100 kHz or more can be regarded as continuous oscillation in practical use. Further, it is preferable that the intensity profile of the light source for main heating has a Gaussian distribution as close as possible.

In order to collect infrared light, a method using a reflecting mirror that reflects infrared light, a method using a lens that collects infrared light using refraction of infrared light, and concentration of energy in a minute space by internal reflection are used. There is a method using a waveguide such as an optical fiber. As a material of the reflecting mirror, a material having a high reflectance with respect to infrared rays is suitable, and as a material of a refraction lens or a waveguide, a substance that transmits infrared rays must be used. An example of the former can be a mirror surface of a metal, and an example of the latter depends on the required wavelength range, but if the wavelength is about 9 to 12 μm, zinc selenide, silicon, germanium, chalcogenide glass, etc. If the wavelength is about 0.9 to 1.2 μm, quartz, lithium fluoride, barium fluoride, fluoride glass or the like can be used.

In the case where the shape of the light beam at the position where the yarn is irradiated with infrared rays is circular, the surface shape of the reflecting mirror or lens may be substantially spherical or parabolic, and the shape is linear. In this case, a cylinder lens or a cylinder mirror may be used. When both are used together, a light beam having an elliptical cross section with an arbitrary aspect ratio can be obtained. When a waveguide is used, the energy distribution at the irradiation site can be controlled by changing the exit size of the waveguide provided near the yarn. By controlling the size of the light beam in the direction parallel to the yarn at the irradiation site, it is possible to control the profile of thermal energy transferred to the yarn. In addition, the irradiation width can be controlled by controlling the size of the light beam in the direction perpendicular to the yarn at the irradiation site. The former is effective for controlling the heating profile of the yarn. The irradiation size can also be adjusted by changing the angle between the yarn and the infrared optical axis. When changing the angle between the yarn and the infrared optical axis, the side closer to the focal point has a larger amount of heat energy given to the yarn, so it can be used to control the thermal energy profile transferred to the yarn. it can. This operation also facilitates irradiation near the first take-off roller. Further, by installing a waveguide such as a reflecting mirror, a lens system, or an optical fiber between the yarn and the light shielding plate, it is possible to simultaneously irradiate infrared rays from a direction opposite to the light source. This is particularly effective when the infrared absorption of the material is low, or when the infrared absorption is too high and the temperature on the light source side increases. By using a reflecting mirror or the like, not only the ratio of radiant energy absorbed by the yarn can be increased, but also the yarn can be heated uniformly from the surroundings, so that the temperature in the cross section of the yarn can be made more uniform.

FIGS. 1 and 3 show examples of a measurement and control system using a laser light source and a lens. FIG. 1 is a view seen from the axial direction of the yarn, and FIG. 3 is a view seen from a direction perpendicular to the fiber axis and the optical axis of infrared rays. The yarn is moved from the first take-up roller 7 to the second
It runs toward the take-off roller 8. In this figure, infrared rays are focused on a focal point 3 by a lens 2. A waveguide such as a reflecting mirror or an optical fiber may be used for the light collecting method. Considering the diameter of the fiber itself and the deflection range 5 of the fiber, the position of the yarn 4 is away from the focal point 3. In this figure, the position of the thread is behind the focal point, but may be in the front. The light shielding plate 6 is provided to absorb infrared rays not absorbed by the yarn, and is air-cooled or water-cooled. As the material, a heat-resistant material such as a brick or a metal whose surface is grounded and coated with a heat-resistant paint is suitable. The measuring device 9 is for measuring changes with time and position such as yarn speed, yarn temperature, yarn diameter, molecular orientation, etc. in the vicinity of the drawing point. It can be adjusted. In order to measure the change due to the position, it is desirable that each measuring device can move in parallel to the running direction of the yarn. The line 10 indicates that the measured profile variation of the yarn diameter, yarn speed and yarn temperature is fed back to the laser output in order to control the drawing point position. FIG. 2 shows an example of a measurement and control system using an optical waveguide and a substantially spheroidal reflector as a method of propagating and condensing an infrared light beam. By using the device shown in this figure, not only the light-collecting efficiency is higher than that shown in FIG. 1, but also the temperature in the cross section of the yarn can be made more uniform because it can be uniformly heated from the surroundings. .
In the case of this system, it is preferable to use an optical waveguide also for measurement.

The fiber material to which the measurement / control system of the present invention can be applied is not particularly limited as long as it is a polymer material capable of absorbing infrared rays and raising the temperature to a softening temperature or higher. Examples of such materials include polyesters, nylons, polyethylenes, polyvinyl alcohols, and polyether ketones.

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited thereto. In each of the following examples, polyethylene terephthalate having an IV of 0.642 g / dl was used, a spinning temperature of 280 ° C., a nozzle diameter of 0.5 mm, 1 hole (L / D = 5), and a discharge rate of 4 min. A monofilament fiber having a birefringence of 0.001 manufactured under a condition of 0.95 g and a winding speed of 250 m / min was used. The refractive index of the fiber was measured by an interference microscope. A mixture of methylene iodide, alpha bromonaphthalene and bromobenzene was used as the immersion liquid, and the refractive index was measured with an Abbe refractometer. The intrinsic birefringence reported for polyethylene terephthalate is about 0.23, and the birefringence 0.001 of the fiber before stretching is 0.004.
Equivalent to the degree. In each of the examples, a laser oscillation light source using carbon dioxide gas as an emission source was used. The wavelength of the light source is 10.6 μm, the beam diameter is 5.0 mm, the beam spread angle is 1.0 mrad, and the beam is focused by a lens. The yarn was positioned behind the focal point and ran in the direction perpendicular to the optical axis of the laser.

[0023]

Example 1 An image near the drawing point when drawing 6 times at a laser output of 22.5 W, a yarn feeding speed of 0.13 m / sec, and a yarn winding speed of 0.8 m / sec was taken at a high speed manufactured by Nack Co., Ltd. Images were taken using a camera MEMRECCAMCi-4. The beam diameter at the laser irradiation position is about 4 mm, and the sending side inflection point of the laser light intensity profile is:
With the intersection point of the yarn and the laser optical axis as the origin, it is located at about 1.0 mm on the sending side. FIG. 4 shows the exposure time of one frame 1 /
One frame is binarized from an image in the vicinity of the stretching point where 2,000 frames were photographed every second at 6000 seconds. The black portion is the yarn, and the neck-like drawing point can be clearly observed. The yarn runs from the left side to the right side of the figure, but the fluctuation of the drawing point position is within the range of about 0.1 mm, so it is possible to accurately measure the diameter change near the drawing point. It is. From this diameter change, the strain and strain rate near the stretching point can be determined. Further, if the tension of the yarn is measured, the stress at an arbitrary position can be calculated from the tension and the diameter, so that the apparent elongational viscosity can be obtained. If the yarn in the deformation area is regarded as an elastic body, the apparent elastic modulus can be calculated. FIG. 5 shows the obtained strain rate and elongational viscosity, and FIG. 6 shows the true strain and elastic modulus.
Shown respectively. In the vicinity of the drawing point, the yarn uniformly warmed by the infrared light flux starts to be deformed by an external force when reaching the softening point. At this time, the apparent elastic modulus and elongational viscosity decrease in the initial stage of stretching, and the strain rate sharply increases. However, the elongational viscosity shows a minimum value at about 6 kPa, and then the strain rate decreases as it starts to increase. , Eventually solidifies. It can be assumed that the elongational viscosity is decreased by softening due to heat generated by deformation, and the increase is caused by the molecular chain orientation.
On the other hand, the apparent elastic modulus converges to a constant value of approximately 100 MPa, and the deformation behavior near the stretching point is apparently
Indicates that it is elastic. Further, from FIG. 6, the stretching start point position in this embodiment is near the point of 1.08 mm on the yarn sending side with respect to the laser optical axis. As mentioned above,
The strain, strain rate, elongational viscosity, elastic modulus, and the like can be calculated from the deformation behavior near the stretching point, firstly because the position of the stretching point is fixed very precisely. In 1/6000 seconds, the yarn is
The image is very clear despite the fact that it has moved by .mu.m and 133 .mu.m on the take-up side, so that the diameter can be read precisely in units of 10 .mu.m. Second,
This is because, in principle, it is guaranteed that the temperature difference in the cross section of the yarn is small. If the temperature difference in the cross section is large,
Even if the apparent elongational viscosity, elastic modulus, etc. are estimated from the deformation profile, the physical meaning of the value is unclear, so it cannot be treated as a physical property value. Variations also increase. On the other hand, the value measured by the present method makes it possible to accurately estimate the temperature at each point, as described in Example 6.
Since the temperature difference in the cross section is also guaranteed to be small,
It may be treated as a physical property value corresponding to an accurate temperature profile / strain profile up to each point. Therefore, according to the present invention, it was possible to measure a transient response characteristic to an ultra-high-speed elongation deformation reaching a strain rate of 10,000 s ⁻¹ or more.

[0024]

Example 2 In the same manner as in Example 1, an image was captured by a high-speed camera while changing only the laser output from 15 W to 25 W, and the results of measuring the stretching point position and the fluctuation width thereof from FIG. 7 are shown in FIG. Show. The position of the inflection point on the transmission side of the laser light intensity profile is indicated by a broken line. With any output, the fluctuation of the stretching point position is about 0.1 mm, so that the stretching point position can be accurately measured. The position of the stretching point is around the inflection point of the irradiation intensity profile near 1.0 mm on the sending side of the laser optical axis. It is suitable for The stretching point moves to the supply side (left side in the figure) as the laser output increases. This is because the higher the output, the sooner the yarn temperature reaches the softening temperature of the fiber (in this case, the glass transition temperature) and the deformation starts. When the output is changed stepwise from 15 W to 25 W, the position of the extension point is 5 m.
It moved to a new equilibrium position in about s, and stabilized in about 15 ms. For this example, the time from when the yarn enters the laser-irradiated area until it reaches the draw point is about 7 ms. The time required for the movement to the equilibrium position and the time required for stabilization at that position correspond to approximately 0.7 times and 2 times the time required for the yarn to reach the stretching point after entering the laser irradiation area, respectively. It was proved to show a sufficiently fast response. Therefore, by controlling the output of the laser, the position of the stretching point can be controlled more precisely. Actually, the amount of light from the vicinity of the stretching point was measured by a photodiode, and the output was fed back to the laser output, whereby the position of the stretching point could be controlled more precisely. In particular, it is effective against pulse-like fluctuations in diameter due to draw resonance during spinning, and when not controlled, the fluctuation width of the drawing point position, which is 0.5 to 1.0 mm, is reduced to about half. Could be reduced. Fluctuations in the drawing conditions create structural weaknesses in the fiber, which is not preferred, especially for increasing the strength. Therefore, by using this drawing point position control system, highly homogenized synthetic fibers with few weak points can be produced, and fibers with high strength can be produced.

[0025]

Example 3 In the same manner as in Example 1, an image was captured with a high-speed camera while changing only the supply speed of the yarn from 6 m to 14 m / min, and the result of measurement of the drawing point position and its fluctuation width was measured. Is shown in FIG. The position of the inflection point on the transmission side of the laser light intensity profile is indicated by a broken line. The higher the yarn supply speed, the more the drawing point moves to the winding side (the right side in the figure). The reason for this is that the higher the yarn supply speed, the longer the traveling distance until the yarn temperature reaches the softening temperature of the fiber. The yarn feed rate is 10 per minute
At m or less, the fluctuation of the stretching point position is about 0.1 mm or less, but becomes unstable suddenly at more than 12 m / min. Under the condition that the position of the stretching point is stable, the position of the stretching point is around the inflection point of the irradiation intensity profile, and it is preferable that the stretching point is located around this in order to fix the stretching point well. Prove that it is suitable for. On the other hand, under the unstable condition, the position of the stretching point is close to the laser optical axis where the irradiation intensity profile shows the maximum value, so that the increasing rate of the irradiation intensity before and after the stretching point is small, and in some cases, it decreases rather. I have. From the above results, it is desirable that the rate of increase in irradiation intensity near the stretching point be as large as possible in order to fix the stretching point satisfactorily.

[0026]

Example 4 In the same manner as in Example 1, only the irradiation range diameter of the laser beam was changed from 2 mm to 5 mm, and an image was captured with a high-speed camera. , Shown in FIG. The position of the inflection point on the transmission side of the laser light intensity profile is indicated by a broken line. The higher the yarn supply speed, the more the drawing point moves to the winding side (the right side in the figure). Also, when compared at the same supply speed, the relative position of the stretching point within the irradiation range,
The larger the irradiation range diameter of the laser beam, the more it moves to the winding side (right side in the figure). This is because the yarn speed relative to the irradiation range diameter is inversely proportional to the irradiation range,
This is because the relative illuminance of the infrared light flux is inversely proportional to the square of the irradiation range, and the relative distance of traveling in the irradiation range before the yarn temperature reaches the softening temperature of the fiber becomes shorter. Under the condition that the position of the stretching point is close to the position of the inflection point on the sending side of the laser light intensity profile, the position of the stretching point is stable, whereas the position of the stretching point is the laser optical axis (that is, the intensity profile has the maximum value). (Position shown), the stretching point becomes unstable. The above results also indicate that it is desirable that the irradiation intensity increase rate before and after the stretching point be as large as possible in order to fix the stretching point favorably. However, when the irradiation range diameter is too small relative to the yarn feeding speed as in the condition of 8, the drawing point is located near the inflection point on the sending side of the laser light intensity profile. Also, the stretching point easily moves to the vicinity of the laser optical axis instantaneously due to a pulse-like increase in diameter due to draw resonance or the like, and is somewhat unstable. In such an example, by feeding back the movement of the stretching point position to the laser output, control is performed so that the stretching point position does not reach near the optical axis.
Very effective.

[0027]

Embodiment 5 Laser output 22.5 W, irradiation diameter 4.2
FIG. 10 shows a yarn speed profile when the yarn was drawn at a yarn feed speed of 0.192 m / sec and a yarn winding speed of 1.06 m / sec. This measurement data is described in FIG. 6 attached to a patent application (Japanese Patent Application No. 11-325879) filed by the same applicant and the same inventor on October 12, 1999 and accepted on the same day 13. It is basically equivalent to a part of what is located and has been calibrated for position. Yarn speed is TSI
It was measured with a laser Doppler velocimeter LS50PT manufactured by KK. The yarn speed suddenly jumps from the supply speed to the winding speed near 1 mm before the optical axis of the carbon dioxide laser. This not only indicates that a rapid change in diameter has occurred in the vicinity, but also that the stretching point start point and the stretching end point are fixed to a section of about 0.5 mm or less in the vicinity. I was assured. However, since the laser Doppler velocimeter used in this example has a measurement range width of about 3 mm, it is not suitable for accurately determining the extension point position and the variation width of the extension point. Since the operating conditions are similar to those of the first embodiment, it should be considered that the extension point position is actually fixed within a section of about 0.1 mm as in the first embodiment.

[0028]

Example 6 The same conditions as in Example 1 were measured.
FIG. 11 shows the measured and estimated temperatures of the yarn near the drawing point. The measured temperature was TMZ7N2-
It was measured by a type 1 radiation thermometer. The position resolution and temperature accuracy of the device, derived by calibration, are also shown in the figure as error bars. Since the fluctuation of the stretching point position is suppressed to about 0.1 mm, the temperature of the yarn rapidly rises when entering the laser irradiation range, and furthermore, it is precisely measured that the temperature rises momentarily near the stretching point position. is made of. The estimated temperature is calculated in consideration of the laser beam irradiated on the yarn, plastic deformation of the yarn, crystallization, and cooling by heat transfer. Assuming a Gaussian output distribution close to the output distribution of the light source actually used, the temperature rise by the laser light is applied to the yarn obtained from the experimental value of the absorption coefficient for infrared light of the same wavelength as the laser light. It was calculated using the absorption rate. The plastic deformation of the yarn was calculated from the actually measured yarn tension, the supply speed and the winding speed. The heat generated by crystallization is based on the Abramie equation assuming one-dimensional heterogeneous nucleation, using the difference in crystallinity measured by differential scanning calorimetry on the fibers before and after drawing and the value of 10,000 per second as the crystal growth rate. did. The contribution of cooling due to heat transfer is small, but Nu = (Nu) as a function of Reynolds number (Re).
An empirical empirical formula of 0.42Re ＾ 0.334 was used. Actually measured values are used for laser power, absorption rate, yarn tension, and crystallinity that have a particularly large effect on the estimated temperature, and quantitative comparison is possible. Although the temperature actually measured before the stretching point is somewhat higher, after the stretching point, the measured temperature and the estimated temperature match well. From this measurement result, it was confirmed that the yarn temperature could be precisely controlled by the laser output and the yarn tension value.

[0029]

As described above, in a synthetic fiber or monofilament melt-spinning process, a drawing process, a direct spinning / drawing process, or a test synthetic fiber drawing apparatus that assumes these, a strong force is applied to a running synthetic fiber yarn. By irradiating a uniform infrared ray, the yarn is quickly and uniformly heated and softened, and the heated yarn is instantaneously stretched, thereby precisely fixing the position of the drawing point, and in the vicinity of the drawing point. Yarn diameter, yarn speed, yarn temperature, molecular orientation, etc., or their temporal variations can be accurately measured. Also, by feeding back the output value corresponding to the measured yarn diameter, yarn speed or yarn temperature profile to the laser output, the drawing point position can be controlled more precisely, and the structure and physical properties can be controlled more precisely. It can be used for the production of a mixed fiber.

[0030]

[Brief description of the drawings]

FIG. 1 is an example of a system for precisely measuring and controlling the vicinity of a drawing point when viewed from a direction perpendicular to a running axis of a yarn and an optical axis of infrared rays. The arrow of the thread means the running direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Infrared light source 2 Lens 3 Focus 4 Yarn 5 Yarn deviation range 6 Shield plate 7 First take-up roller 8 Second take-up roller

FIG. 2 is a schematic view of a yarn rapid heating device using an optical waveguide and a substantially spheroidal reflector as viewed from a direction perpendicular to a running axis of the yarn and an optical axis of infrared light. The arrow of the thread means the running direction.

[Explanation of symbols]

2 Optical waveguide (guides light beam from infrared light source) 3 Emission point of optical waveguide and focal point of substantially spheroidal reflecting mirror 1 4 Thread (passes near focal point 2 of substantially spheroidal reflecting mirror) 5 Thread Deflection range 6 Substantially spheroidal reflecting mirror 7 First take-up roller 8 Second take-up roller

FIG. 3 is an example of a system for precisely measuring and controlling the vicinity of a drawing point viewed from the running axis direction of a yarn. An arrow drawn downward from the measurement device indicates a measurement direction, and an arrow drawn downward and left indicates feedback control of output.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Infrared source 2 Lens 3 Focus 4 Yarn 5 Yarn deviation range 6 Shield plate 9 Measuring device (high-speed camera, yarn thermometer, yarn speedometer, light meter, etc.) 10 Feedback control system

FIG. 4 Example 1 Deformation profile of yarn. An image near the stretching point photographed at an exposure time of 1/6000 seconds was binarized and shown. The black part is the thread. The supply speed of the yarn is 0.13 m / s, and the winding speed of the yarn is 0.8 m / s. The yarn runs from the left side of the screen to the right side. The fluctuation width of the stretching point position is about 0.1 mm.

FIG. 5 is a graph in which an apparent elongational viscosity and a strain rate are obtained from a deformation profile of Example 1, and plotted with respect to a position based on a laser optical axis. Open circles indicate apparent elongational viscosity (left axis), and solid circles indicate strain rate (right axis). In the vicinity of the stretching point, the apparent viscosity decreases after the start of the deformation, and the strain rate sharply increases. However, the deformation is completed as the apparent viscosity rapidly increases again after showing the minimum value of about 6 kPa. The reason why the apparent elongational viscosity decreases is that the yarn temperature rises due to the heat generated by deformation, and the cause of the sudden increase is considered to be the full extension of the molecular chain.

FIG. 6 shows apparent elastic modulus and true strain obtained from the deformation profile of Example 1, and plotted against a position based on the laser optical axis. A white circle indicates the apparent elastic modulus (left axis), and a black circle indicates the true strain (right axis) at that point. After the start of the stretching deformation, the apparent elastic modulus decreases and shows an almost constant value.

FIG. 7 shows the position of the stretching point and the range of variation thereof.
The horizontal axis is the origin along the optical axis of the carbon dioxide laser, the position along the running direction of the yarn, and the vertical axis is the laser output. The horizontal line indicates the position of the stretching point at each output and the fluctuation range thereof. The variation range of the stretching point is about 0.1 mm at any output and is well fixed. Further, as the laser output increases, the drawing point moves to the yarn supply side (left side in the figure). The vertical dashed line indicates the position of the transmission-side inflection point of the laser light intensity profile.

FIG. 8 shows the position of the stretching point and the range of variation thereof.
The horizontal axis is the origin along the optical axis of the carbon dioxide laser, the position along the running direction of the yarn, and the vertical axis is the laser output. The horizontal line indicates the position of the stretching point at each output and the fluctuation range thereof. The vertical dashed line indicates the position of the transmission-side inflection point of the laser light intensity profile.

FIG. 9 shows the position of a stretching point and its fluctuation range.
The horizontal axis represents the origin along the optical axis position of the carbon dioxide laser, the position along the running direction of the yarn, and the vertical axis represents the irradiation range diameter of the laser. The horizontal line indicates the position of the stretching point at each output and the fluctuation range thereof. The broken line indicates the position of the inflection point on the transmission side of the laser light intensity profile.

[Explanation of symbols]

1 Yarn supply speed 5 m / min: stable 2 Yield supply speed 6 m / min: stable 3 Yarn supply speed 6 m / min: stable 4 Yield supply speed 8 m / min: stable 5 Yield supply speed 10 m / min: stable 6 Yarn supply speed 12 m / min: unstable 7 Yarn supply speed 14 m / min: unstable 8 Yarn supply speed 14 m / min: slightly unstable 9 Send laser light intensity profile Position of side inflection point 10 Out of laser irradiation range

FIG. 10 shows a measurement result of a yarn speed profile in Example 5. The horizontal axis represents the origin along the optical axis position of the carbon dioxide laser, the distance along the running direction of the yarn, and the vertical axis the yarn speed. This corresponds to the mode value of the yarn speed for 3 seconds within a range of ± 1.5 mm around each point.

FIG. 11 shows a yarn temperature profile and its estimation result. The horizontal axis has the origin along the optical axis position of the carbon dioxide laser, the distance along the running direction of the yarn, and the vertical axis the yarn temperature. The broken line shows the position of the stretching point and the irradiation range of infrared rays. The points indicate the measured temperatures, and the solid lines indicate the estimated temperatures. The error bar of the actually measured temperature means the temperature accuracy and the position resolution at the corresponding temperature.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3B154 AA06 AB02 AB04 BA53 BB09 BB12 BB18 BC42 BF04 BF14 BF23 CA01 CA02 CA09 CA12 CA29 CA33 DA05 4L036 AA01 MA04 MA33 MA34 PA03 PA12 UA21 UA25 4L045 AA05 BA01 BA60 DA42 DA46

Claims (8)

[Claims] 1. A step of stretching a yarn between a first take-up roller and a second take-up roller, a melt spinning step of stretching a yarn melt-spun from a spinneret by a take-up roller or a monofilament manufacturing step, and a step of spinning a monofilament. The melt spun yarn is once cooled and solidified,
In a direct spinning / drawing step of drawing between a take-up roller and a second take-up roller, or in a test synthetic fiber drawing apparatus assuming these, a synthetic fiber is irradiated by irradiating a powerful synthetic infrared ray to a running synthetic fiber yarn. After rapidly and uniformly heating and softening the yarn, it is deformed by external force to precisely fix the drawing point position, and the yarn diameter, yarn speed, yarn temperature, molecular orientation, elongational viscosity,
A measuring system characterized by precisely measuring a strain rate, an elastic modulus, a strain amount, or a temporal variation thereof. 2. The position of the drawing point is controlled more precisely by feeding back the fluctuation of the profile of the yarn diameter, the yarn speed or the yarn temperature obtained by the measuring system according to claim 1 to the laser output, and the uniform fiber is obtained. A control system characterized by producing fibers of structural and physical properties. 3. The measurement and control system according to claim 1, wherein the variation width of the drawing point position does not exceed 1 mm or does not exceed the distance over which the drawn yarn travels within a time of 10 ms. 4. The running speed of the drawn yarn is 0.1 m / sec.
The measurement and control system according to claim 1, wherein the irradiation time of the infrared light flux to the yarn does not exceed 0.1 second. 5. The measurement / control system according to claim 1, wherein the stretching conditions are set such that the stretching point position is near a point where the rate of increase of the infrared light flux intensity profile is maximized. 6. The molecular orientation of the yarn before stretching is 0.1 or less, typically 0.01 or less, and the stretching ratio is 4 or more,
The measurement and measurement according to claim 1, which is typically 5 times or more.
Control system. 7. The measurement / control system according to claim 1, wherein a coherent light source utilizing laser oscillation is used. 8. The measurement / control system according to claim 1, wherein a substantially spheroidal reflecting mirror is used for focusing the infrared light beam.