JPH03287813A - Direct spinning and drawing of polycaproamide fiber - Google Patents

Abstract

PURPOSE:To efficiently obtain polycaproamide fiber yarn having high orientation degree, high strength and excellent thermal dimensional stability by subjecting polycaproamide chips having a specific relative viscosity to melt spinning, direct drawing to give intermediate orientated fiber yarn, further drawing the yarn in a plasma atmosphere and subjecting to relaxing heat treatment. CONSTITUTION:Polycaproamide chips having >=3.0 relative viscosity are subjected to melt spinning, passed through a high-temperature zone and a cooling zone and directly drawn to give intermediate orientated yarn having 20X10<-3> to 40X10<-3> double refraction and <=1.130g/cm<3> density, which is provided with 1.0-5.0g/d tension in a plasma atmosphere under reduced pressure, further drawn at 1.2-5.0 times, drawn at a second stage or not drawn and subjected to 0-10% relaxing heat treatment to give polycaproamide fiber yarn having >=55X10<-3> double refraction, useful as rubber-reinforcing material, etc.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method for direct spinning and drawing of polycapramide fibers, and more specifically, to a method for producing polycapramide fibers having high strength and excellent thermal dimensional stability, which are particularly suitable for industrial material applications. The present invention relates to a method for efficiently producing fibers by direct spinning and drawing.

[Prior art] Polyamide fibers have high strength, excellent adhesive properties, fatigue resistance, etc., and are therefore used in various industrial materials, such as rubber reinforcing materials for tire cords, power transmission belts, conveyance belts, etc., and seat belts. It is used for fishing nets, safety nets, sewing thread, cover sheets, bag fabrics, etc.

However, there is a strong demand for reducing the cost of the material fibers in the various products mentioned above, and in order to satisfy this demand, even higher strength is required. At the same time, in order to ensure a high yield in the product manufacturing process, there is a need for further improvement in the thermal dimensional stability of the material fibers.

Hitherto, as high-strength polycapramide fibers and methods for producing the fibers, JP-A-58-54018 and JP-A-62-183109 are known.

The fiber described in JP-A-58-54018 has a strength of 8. l1g/d~8.85g/d, cutting elongation 22.7%~23.0%, dry heat shrinkage rate (150°C) 1
．． 5% to 3.3% and a crystal orientation degree (fゎ) of 0.94. As a method for producing fibers having these characteristics, a polycapramide polymer having a sulfuric acid relative viscosity of 3.0 or more is used. A polycapramide-based polymer containing a copper salt and/or an antioxidant is melt-spun, and the spun yarn is passed through a zone surrounded by a tube in which an atmosphere of at least 10 cTII or higher is heated to a temperature higher than the melting point of the polycapramide under the spinneret. After that, the yarn is rapidly cooled and taken off, and the yarn that has passed through the take-up roll is taken off at a take-off speed such that the birefringence of the yarn is 25 x 10-'' or more, and the yarn that has passed through the take-up roll is drawn at a stretching ratio of 3.5 times or less. The purpose is to obtain polycapramide fibers with high strength, excellent dimensional stability, and fatigue resistance.

The fiber described in JP-A-62-133109 has a strength of 11.10 g/d-11°61 g/d, an elongation of 14.2% to 16.4%, and a boiling water shrinkage rate of 7. .2%
~9.8%, birefringence 60.3X10-3~62.3X
10-1, crystal orientation (fc) is 0.94 to 0.95,
The fiber has an amorphous molecular orientation function (F) of 0.72 to 0.75, and as a method for producing fibers having this characteristic, melt-spinning polycapramide chips with a sulfuric acid relative viscosity of 3.0 or more is used. and at least 10 cIT from the spinneret
A heating cylinder in which one or more atmospheres are kept at 200°C to 400°C is provided, and a cooling device is provided below the heating cylinder to delayly cool the spun yarn. The cooled and solidified yarn is coated with an oil agent and run at a speed of 1500 m/min or more, preferably 2
Wind up at 000 m/min to 6000 m/min. The birefringence of the pulled yarn is 20×10-3 to 45
X10-'', and the yarn is heated at 80°C to 250°C during the drawing process.
Stay in a high temperature atmosphere of ℃ for 0.2 seconds or 150℃~
Highly oriented polycapramide fiber with birefringence of 58X10-' or higher is obtained by performing a first stage of heating and stretching using high-temperature pressurized steam at 300°C, and then further performing a second stage of heating and stretching at a higher temperature than the first stage. This is what you get.

In addition, as a method for modifying the surface of organic fibers, especially polyester fibers by plasma treatment, Japanese Patent Application Laid-Open No. 61-1988
No. 0, JP-A-61-42546, and JP-A-62-238871 are known.

[Problem to be solved by the invention] The above-mentioned JP-A-58-54018 and JP-A-62
The polycapramide fiber obtained by the method described in Publication No. 133109 has a low strength of less than 12 g/d, a low strength-elongation product, and a high shrinkage rate in boiling water, making it difficult to use as an industrial material. Therefore, polycapramide fibers with higher properties are required.

JP-A-61-19880, JP-A-61-4 mentioned above
The inventions described in JP-A-2546 and JP-A-62-238871 claim that low-temperature plasma treatment is effective for surface modification of polyester fibers. The fiber surface is modified by crosslinking, etching, introducing active groups, or graft polymerization with a specific polymer by subjecting it to low-temperature plasma treatment. In particular, an example is described in which low-temperature plasma treatment is applied to polyester fibers for industrial materials.

However, the low-temperature plasma treatment of polyester fibers is concerned with improving the adhesion between polyester fibers and rubber, and cords made of already drawn and heated polyester fibers are treated with low-temperature plasma, followed by resorcinol-formaldehyde. The present invention discloses a method of treating with a mixture of an initial condensate and a rubber latex.

Therefore, it can be said that the above-mentioned plasma treatment technique merely utilizes the surface treatment effect, which is recognized as an effect of low-temperature plasma treatment, to improve adhesion.

Furthermore, the effects of improving the mechanical and thermal properties of polycapramide fibers, such as improving the high strength and thermal dimensional stability, which are the objectives of the present invention described below, are not achieved.

An object of the present invention is to provide a method for efficiently producing polycapramide fibers having high strength and excellent thermal dimensional stability.

Another object of the present invention is to develop polycapramide fiber manufacturing conditions and appropriate low-temperature plasma treatment, whereas conventional low-temperature plasma treatment has been developed as a surface treatment technology based on the idea that it acts only on the surface of fibers. By selecting and combining these conditions, we discovered that the action of plasma treatment can reach the inside of the treated fiber, and by utilizing this as a new drawing method, we were able to create polycapramide fibers that are ideal for industrial fibers. The objective is to provide a method for efficiently manufacturing.

[Means and effects for solving the problems] The constitution of the present invention is as follows: (1) In the direct spinning and drawing method of polycapramide fiber, polycapramide chips obtained by melt-spinning polycapramide chips having a relative viscosity ηr of 3.0 or more The birefringence of polycapramide fiber is
20X10-3 to 40X10-3, density 1.130g
/cm" or less, the intermediately oriented yarn is then led to a drawing zone, and at least the first stage of stretching in the stretching zone is carried out at a tension of 1.0 to 1.0 cm" or less.
5.0 g/d and stretched in a range of 1.2 to 5.0 times to obtain a drawn yarn, and then subjected to a second drawing, or obtained without performing a second drawing. The drawn yarn is then led to a relaxation heat treatment area and subjected to a relaxation heat treatment of 0 to 10%,
1. A method for direct spinning and drawing of polycapramide fibers, characterized in that the degree of orientation is high with birefringence of 55 x 10-3 or more.

(2) In the direct spinning/drawing method for polycapramide fibers described in (1) above, the polycapramide chips are melt-spun and the spun polycapramide fibers have a birefringence of 20×10-” before reaching the take-up roller. ~40X10-
8(7) A method for direct spinning and drawing of polycapramide fibers, characterized by forming intermediately oriented yarns.

(3) In the method for direct spinning and drawing of polycapramide fibers described in (1) and (2) above, the polycapramide chips are melt-spun, cooled, taken to a Yumitori roller, and then pre-stretched, so that the birefringence is 20×10. -” ~40X10-
``A method for direct spinning and drawing of polycapramide fibers, characterized by forming intermediately oriented yarns.''

(4) In the method for direct spinning and drawing of polycapramide fibers described in (1), (2), and (3) above, the plasma used in the drawing zone is non-polymerizable, and the pressure of the plasma atmosphere is 0.5 to 50 Torr. Yes 1, applied voltage 0.5-1
1. A direct spinning and drawing method for polycapramide fiber, characterized by achieving 0 KV.

It is in.

Next, the configuration of the present invention will be explained in detail below.

The polymer used in the direct spinning/drawing method for polycapramide fibers according to the present invention (hereinafter referred to as the "invention fibers") is such that 95 mol% or more of the repeating structural units of the molecular chain are composed of polycapramide, and the copolymerization component is in a range of less than 5 mol%. It may be contained. Examples of the copolymerization component include polyhexamethylene adipamide, tetramethylene adipamide, hexamethylene sebamide, hexamethylene terephthalamide, hexamethylene isophthalamide, xylylene phthalamide, and the like. If the copolymer component is contained in an amount of 5 mol % or more, crystallinity decreases, the melting point decreases, and thermal dimensional stability decreases, which is not preferable.

The polycapramide is formed into polycapramide chips having a relative viscosity ηr of 3.0 or more, and is spun using a melt spinning device. As a method for making the relative viscosity ηr 3.0 or more, it can be obtained by further subjecting polycapramide chips obtained by polycondensation to solid phase polymerization.

The polymer melted in the melt spinning device is spun out from the spinneret hole to become a spun yarn. In particular, when the spun yarn is spun at high speed so that the birefringence is in the range of 20 x 101 to 40 x 10'' before reaching the take-up roll, the spun yarn is placed directly under the spinneret without being immediately quenched. The material is delayed cooled through a high-temperature atmosphere region, then introduced into a cooling region, blown with cold air, and passed through a spinning tube to form yarn.

The above-mentioned high-temperature atmosphere region has a high temperature of 180 to 340°C and a length of 5 to 600 mm, and the conditions of this high-temperature atmosphere region include the viscosity of the yarn to be spun, the thickness of the single yarn, It is selected and set according to quality setting conditions such as draft rate and number of single threads.

The above-mentioned cooling area is for gas of 120℃ or less at 15 to 50m/
Spray within the speed range of 1 minute. The conditions of this cooling zone are also selected and set according to quality setting conditions such as the viscosity of the yarn to be spun, the thickness of the single yarn, the draft rate, and the number of single yarns.

By setting each condition in the high temperature atmosphere region and the cooling region within the above ranges, the cooling gradient pattern of the spun yarn is made appropriate.

By applying the above-mentioned high-temperature atmosphere zone and cooling zone to control the structure formation process of the spun yarn, the quality of each single yarn is stabilized, and the quality of each single yarn is stabilized. Polycapramide fibers can be obtained.

The cooled and solidified spun yarn is provided with a spinning oil,
200 m/min or more, preferably 300 m/min to 50 m/min
After being wound around a roller rotating at 00 m/min, it is subsequently stretched. The polycapramide fiber that is wound around a roller and subsequently stretched has a density of 1.130 g/cm.
"Hereinafter, it is an intermediately oriented yarn with a birefringence of 20X10-8 to 40X10-', or an intermediately oriented yarn with a birefringence of less than 20X10-".

If the birefringence of the polycapramide intermediately oriented yarn obtained by spinning under the above conditions exceeds 40 x 10-'', oriented crystallization will proceed, so the fiber structure can be idealized by drawing in the plasma atmosphere, that is, plasma drawing. It is difficult to form the film precisely, and sufficient effects cannot be obtained.

When the birefringence of the polycapramide fiber subjected to plasma stretching is smaller than 20×10 −s, the thermal dimensional stability is sufficiently improved and no polycapramide fiber is obtained.

The birefringence of the intermediately oriented yarn is 20X10-3 to 40X1.
0-'', the spinning speed is 5000 m/min or less, preferably in the range of 2000 m/min to 4500 m/min.

The birefringence of the polycapramide fiber taken up by the take-up roller is 20.
If it is smaller than X10-'', preliminary stretching is performed by a factor of 3.0 or less before plasma stretching, so that the birefringence is in the range of 20X10-8 to 40XIO-''.

As mentioned above, the relative viscosity ηr is 3.0 or more and the birefringence is 2.
The intermediately oriented polycapramide fibers of 0.times.10@-3 to 40.times.10@-' are subsequently introduced into a drawing zone and drawn. The stretching is
It is carried out in a plasma atmosphere under a tension of 1.0 to 5.0 g per denier within a range of 1°2 to 5.0 times, and then led to a relaxation heat treatment zone, and is heated by 0 to 10%, preferably 4. ~1
By applying a relaxation heat treatment in the range of 0%, highly oriented polycapramide fibers having a birefringence of 55×10 −” or more can be obtained.

In order for the polycapramide fiber obtained by the method according to the present invention to be used mainly as a fiber for industrial materials, it is necessary to have high strength and excellent thermal dimensional stability, which are the objectives of the present invention. It is essential to use the polymer, and the relative viscosity ηr of the polymer is 8.0 or more.

If the relative viscosity ηr of the polymer is less than 8.0, the strength of the resulting polycapramide fibers may not reach a satisfactory value.
0-5. By setting the content of O within the range, the yarn-spinning property is improved and the combination with plasma stretching conditions becomes easy.

The plasma used in the plasma stretching described above is generated by applying a high voltage in a reduced pressure container filled with a specific gas, and such discharge can be spark discharge, corona discharge,
Although there are various types of discharge such as glow discharge, glow discharge is particularly preferred because of its uniform discharge and excellent activation effect. As the discharge frequency, low frequency, high frequency, or microwave can be used, and direct current can also be used.

Examples of the gas used in the present invention include Ar.

N2) Ho, CO3, co, Ox, H,0SCF,,N
H4, H! , air, and non-polymerizable gases mixed therewith are preferred, and Ar5N2)CO2)H,O1 air, which does not have a particularly strong etching effect, is preferred, but air is particularly preferred from a practical standpoint.

The plasma used for plasma stretching in the method for producing fibers of the present invention is 0.01 to 50T.

From the viewpoint of discharge stability, it is preferable to conduct the reaction under a pressure of 0.5 to 20 Torr, preferably 0.5 to 20 Torr. Further, the applied voltage is 0.5 to 10 KV, preferably 1 to 8 KV.

The stretching ratio in the plasma stretching is 1.2 to 5.0 times, preferably 1.4 times, depending on the physical properties of the intermediately oriented undrawn yarn that is spun and directly stretched, or the partially stretched intermediately oriented yarn. It is selected within the range of ~4°0 times.

By using the plasma stretching, it is possible to stretch while suppressing crystallization compared to the conventional hot stretching method, and therefore, it is possible to stretch at a high magnification, and the resulting polycapramide fiber can be highly oriented. .

The plasma stretching may be performed in one stage or in multiple stages of two or more stages.

Plasma conditions are changed depending on the physical properties and form of the undrawn polycapramide yarn to be subjected to drawing, plasma applied voltage, atmospheric gas, degree of atmospheric pressure reduction, drawing speed, etc. However, the birefringence of polycapramide fiber obtained by plasma drawing is 55× Stretching is performed by combining plasma conditions to obtain a high degree of orientation of 10-3 or higher.

The plasma-stretched polycapramide fibers described above may be further subjected to conventional hot stretching or heat treatment.

The apparatus used to produce the fibers of the present invention is not particularly limited, but a continuous type with seals before and after the vacuum container is used, and heat is applied before and after the plasma drawing zone as necessary. Boards, hot rolls, etc. may be connected.

The fibers of the present invention obtained by the above-mentioned plasma stretching have a lower molecular weight drop during stretching than those produced by conventional hot stretching. Also, the density (ρ) is somewhat low, and the birefringence (, d
n), it can be seen that crystallization is suppressed and high orientation is achieved.

This phenomenon indicates that smooth stretching is achieved by plasma stretching.

The high-strength polycapramide fiber obtained by the method according to the present invention is particularly preferably used for industrial material applications, and specifically, by heating the fiber and applying an adhesive such as resorcin, formalin, or latex. It is preferably used as a rubber reinforcing material for tires, power transmission belts, conveyor belts, etc.

Further, the fibers can be knitted or woven and preferably used as thick cloth or thick belt.

Furthermore, by subjecting the fibers to a strong twisting process, they can be preferably used as sewing threads.

Furthermore, the fibers can be knitted and preferably used as a net.

[Examples] Examples 1 to 3 and Comparative Examples 1 to 4 Polycapramide chips having a sulfuric acid relative viscosity ηr of 3.60 were melt-spun using a 40 mmφ extruder type spinning machine.

The temperature of the molten polymer in the spinning pack was 285° C., and the spinneret used had a hole diameter of 0850 mm and a number of holes of 136. A heating cylinder was installed under the back of the cap so that a 25 cm area directly below the cap was a high temperature atmosphere zone of 310°C. After the yarn spun from the spinneret passed through the high-temperature atmosphere zone, it was immediately cooled by cold air at 20° C. blown out from the annular cooling device. The cold air blowing length of the annular cooling device is 35cm.
The speed of the cold air on the blowing surface was 30 m/min.

After the cooled and solidified yarn is oiled, it is wound around a take-up roll that rotates at a specific speed, and then continuously guided to a plasma stretching device with an effective processing length of 1.5 m installed between a hot stretching roll and the above-mentioned process. Plasma stretching was performed at various stretching ratios between a take-up roll and a hot stretching roll, followed by relaxation heat treatment between the hot stretching roll and a tension adjustment roll, and then the film was wound up. The physical properties of the undrawn yarn were measured by taking the yarn wound around a take-up roll. In addition, by changing the spinning discharge amount according to the spinning conditions, the wound yarn was made into 840 denier and 136 filament.

For comparison, a case in which the plasma stretching device was removed and one-stage stretching was performed, and a case in which an intermediate stretching roll was disposed between the take-off roll and the hot stretching roll and two-stage stretching were performed are shown.

The spinning conditions are shown in Table 1, and the obtained fiber properties are shown in Table 2. (Examples 1 to 3, Comparative Examples 1 to 3) Table 2 also shows the characteristics of high-strength polycapramide fibers (nylon 6 fibers) that have been put into practical use. (Comparative Example 4) It has been shown that the polycapramide fiber obtained by the method of the present invention has high strength and excellent thermal dimensional stability.

(The following is a blank space) [Effects of the Invention] According to the direct spinning/drawing method for polycapramide fibers according to the present invention, an intermediately oriented yarn obtained by relatively low speed spinning is directly drawn at a high magnification in plasma, and then subjected to relaxation heat treatment. It is extremely efficient to obtain polycapramide fibers suitable for industrial use.

Furthermore, according to the method for direct spinning and drawing of polycapramide fibers according to the present invention, spinning, drawing, and relaxation heat treatment can be performed continuously in one step, and the spinning state in these spinning steps can be stably performed. , it is possible to make the spinning properties and the quality of the obtained polycapramide fibers uniform.

Furthermore, the polycapramide fiber according to the present invention has high strength and excellent thermal dimensional stability, and is extremely suitable as a rubber reinforcing material for tires, belts, etc., as well as seat belts, fishing nets, sewing threads, tents, tarpaulins, slings, safety nets, etc. It is preferably used for various industrial applications.

Claims (4)

[Claims] (1) In the direct spinning and drawing method of polycapramide fiber, polycapramide chips with a relative viscosity ηr of 3.0 or more are melt-spun, and the birefringence of the obtained polycapramide fiber is
20×10^-^3 to 40×10^-^3, density is 1.
The intermediately oriented yarn has a weight of 130 g/cm^3 or less, and the intermediately oriented yarn is then led to a drawing zone, and at least the first stage of stretching in the stretching zone is performed at a tension of 1.0 to 5 in a reduced pressure plasma atmosphere. .0 g/d and stretched in a range of 1.2 to 5.0 times to obtain a drawn yarn, and then subjected to a second drawing, or obtained without performing a second drawing. A method for direct spinning and drawing of polycapramide fibers, characterized in that the drawn yarn is subsequently introduced into a relaxation heat treatment zone and subjected to a relaxation heat treatment of 0 to 10% to achieve a high degree of orientation with birefringence of 55 x 10^-^3 or more. (2) In the method for direct spinning and drawing of polycapramide fibers as set forth in claim 1, the birefringence of the polycapramide fibers is 20 during the time between melt spinning the polycapramide chips and reaching the take-up roller for the spun polycapramide fibers. ×10^-^3~4
1. A method for direct spinning and drawing of polycapramide fibers, characterized by forming intermediately oriented yarns of 0x10^-^3. (3) In the method for direct spinning and drawing of polycapramide fibers according to claims 1 and 2, the polycapramide chips are melt-spun, cooled, taken up by a take-up roller, and pre-stretched. Refraction is 20×10^-^3~
1. A method for direct spinning and drawing of polycapramide fibers, characterized by forming intermediately oriented yarns of 40×10^-^3. (4) In the method for direct spinning and drawing of polycapramide fibers according to claims 1, 2, and 3, the plasma used in the drawing zone is non-polymerizable, and the pressure of the plasma atmosphere is 0. A method for direct spinning and drawing of polycapramide fibers, characterized in that the applied voltage is 5 to 50 Torr and 0.5 to 10 KV.