JPS61289112A - Polyvinyl alcohol fiber having ultra-high tenacity - Google Patents

Abstract

PURPOSE:To provide the titled fiber composed of a polyvinyl alcohol polymer having a weight-average molecular weight higher than a specific level, having high tensile strength and suitable as tire cord, seat belt, general rubber reinforcing material, rope, cable, etc. CONSTITUTION:A polyvinyl alcohol polymer having a weight-average molecular weight of >=1X10<6>, preferably >=1.5X10<6> is dissolved in a solvent such as dimethyl sulfoxide to obtain a spinning dope. The dope is extruded through a spinning nozzle and coagulated or solidified by cooling. The solidified yarn is desolvated, dried and super-drawn to obtain an ultra-high tenacity polyvinyl alcohol fiber having a tensile strength of >=25/d. Preferably, the fiber has no long-period image in the small-angle X-ray scattering and the peak height of the principal mechanical loss tangent of the fiber is <=0.10.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses ultra-high strength polyvinyl alcohol (hereinafter referred to as PV
(abbreviated as A) type fiber, more specifically, the conventionally known P
It relates to PVA-based fibers that have high mechanical properties that are incomparable to VA fibers and comparable to aramid fibers.

[Prior Art] Conventionally, PVA fibers have superior mechanical properties, chemical resistance, weather resistance, etc. compared to fibers such as nylon and polyester.
Fishing nets and ropes take advantage of these characteristics.

It is widely used as an industrial fiber material for tire cords, rubber reinforcing materials, etc.

Such PVAI fibers are usually produced by using a PVA aqueous solution as a spinning stock solution, and extruding it through a spinneret into a coagulation bath 2, such as a saturated inorganic salt aqueous solution, and coagulating it.The obtained coagulated yarn is washed with water, stretched, dried, and then subjected to acetalization, etc. It is manufactured through a water insolubilization process. In such a manufacturing method, in order to improve the mechanical strength of the resulting PVA fiber, an aqueous solution containing boric acid or a salt thereof is used as a spinning stock solution, and spinning is carried out in an alkaline base coagulation bath (Japanese Patent Publication No. 48-1989). No. 9209) A method for spinning a PVA aqueous solution in a concentrated alkaline coagulation bath.
Publication No. 86) and the like have been proposed.

However, although the PVA fibers obtained by these methods do have improved mechanical properties compared to conventional PVA fibers, they do not have a high It did not indicate any mechanical properties.

On the other hand, recently, after discharging a semi-diluted solution of an ultra-high molecular weight polyolefin polymer from a spinneret hole and cooling the discharged thread to form a -H gel, the resulting gelled thread was desolvated as shown below. It was found that fibers with significantly higher strength and modulus of elasticity can be obtained by ultra-stretching (referred to as gel spinning method).
For example, JP-A-56-15408, JP-A-58-52
28), and attempts have also been made to apply the gel spinning method to PVA polymers to obtain high strength and high elastic modulus (Japanese Unexamined Patent Publication No. 130314/1982).

In other words, ultra-high polymerization degree PVA obtained by a special polymerization method (strict rectification of vinyl acetate monomer and long-time ultraviolet polymerization lasting about 100 hours at temperatures below -40°C) is added to a polyhydric alcohol solvent such as glycerin. Gel spinning is performed from a low-concentration spinning stock solution, and after solvent removal and stretching, the
A PVA fiber with an unprecedentedly high tensile strength of g/d has been obtained.

However, the above-mentioned fiber is the above-mentioned aramid fiber.

For example, the tensile strength of "Kevlar" manufactured by DuPont, which is currently commercially produced, is about 22 g/d, which is considerably inferior to this.

The present inventors have conducted extensive research in order to obtain a fiber having a tensile strength exceeding that of "Kevlar" from a linear ultra-high molecular weight PVA-based polymer, and as a result, they have arrived at the present invention.

[Problems to be Solved by the Invention] The purpose of the present invention is to greatly exceed the tensile strength of 19 g/d of the PVA fiber in the example described in JP-A-59-130314, and also to improve the It even exceeds the tensile strength of typical aramid fibers. Ultra-high strength PV
To provide A-based fibers.

[Means for Solving the Problems] The above-mentioned object of the present invention is to produce an ultra-high-grade polymer having a tensile strength of 25 g/d or more, which is essentially polyvinyl alcohol and is made of a polymer having a weight average molecular weight of 1 x 106 or more. Strength can be achieved by using polyvinyl alcohol fibers.

That is, according to detailed experiments by the present inventors, the ultra-high strength polyvinyl alcohol fiber of the present invention having a tensile strength of 25 q/d or more is: (1) a PVA polymer having a weight average molecular weight of 1 x 106 or more; The solution is used as the spinning stock solution.

(2) Dry-wet spinning method (details described below) using the spinning stock solution at a spinning draft (definition described below) of 1°0 or less and a discharge rate such that the single filament fineness of the final drawn yarn is 5 deniers or less; or According to the gel spinning method disclosed in Japanese Patent No. 13031, it is spun out from a nozzle and solidified or solidified by cooling.

(3) The solidified thread is passed through a solvent extraction step (during which drawing may be involved), and the solvent is removed.

(4) After applying an appropriate process oil to the desolventized yarn, it is dried.

(5) The melting temperature of the dried yarn in heated air or an inert atmosphere (e.g. nitrogen gas)
”・1.9 Ultra-stretch at low speed directly below.
1. Yoyo91. circle. . 8ka, waka1. Yo. A1.The distinctive feature of I-mei is item (1) of the above five items.
jUsing a hot ultra-high molecular weight polymer, (2) -
! By using a special spinning method under a constant draft, and by using the non-contact type dry heat stretching method described in (5),
11° Stretching at a high magnification until it shows a fiber structure,
.

The present invention was first achieved by an integral combination of these.
'.

This results in ultra-high strength PVA fibers.

By ultra-stretching in a non-contact dry heat atmosphere as described in (5) above,
), a fiber structure in which the molecular chains are substantially fully extended is formed, and the amorphous part is also significantly oriented.
The PVA fiber of the present invention which does not have a long period structure in 1))1] lff17'J"1*6t"6・
]・1 The PVA fiber w4#1 of the present invention has the highest tensile strength among the conventional lip fibers. /d), and furthermore, no long-period retention was observed, and the tan δ value of the mechanical principal dispersion peak was 0.10 or less, and the supramolecular orientation,
Has high crystallinity. This is a completely new fiber.

Next, a specific manufacturing example of the ultra-high strength PVA fiber according to the present invention will be described.

First, a PVA polymer having a weight average molecular weight of 1.times.10.sup.6LX is dissolved in a solvent to prepare a solution containing 2 to 12 percent by weight of the PVA polymer. The solution is forced through a multi-hole nozzle through a layer of air or an inert gas atmosphere into a coagulation bath or into a cooling liquid bath.

Here, the former spinning method in which the fiber is extruded into a coagulation bath is a "dry-wet spinning method," and the solvent of the PVA-based polymer and the coagulant cause mutual diffusion in the coagulation bath.

On the other hand, the latter spinning method in which the fibers are extruded into a cooling liquid bath is a ``gel spinning method'' similar to that disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 59-130314. Since they are not miscible with each other, mutual diffusion does not occur; in other words, the fibrous solution extruded from the nozzle only gels by cooling, and the resulting gelled yarn is substantially the same as the spinning dope. It has a composition.

Although the PVA-based IIi fibers of the present invention can also be obtained by the above-mentioned spinning methods, each method will be described in detail below.

As for the PVA polymer constituting the PVA fiber of the present invention, its weight average molecule! (MW) is 1×10 or more, preferably 1.5×106 or more, more preferably 2×1
06 or higher and is not particularly limited as long as it has fiber-forming properties, for example, partially saponified PVA, completely saponified PV
A, and PVA copolymers obtained by copolymerizing a small amount of vinyl monomers that are copolymerizable with vinyl alcohol, among which completely saponified PVA is most preferred.

In the dry-wet spinning method, dimethyl sulfoxide (DMSO) is used as a solvent for the PVA-based polymer.

Organic solvents such as glycerin, ethylene glycol, diethylene triamine, ethylene diamine, and phenol, water, zinc chloride, and rhodan soda.

Examples include aqueous solutions of inorganic salts such as calcium chloride and aluminum chloride, and mixed solvents thereof. Preferably, solvents with high dissolving power for the polymer are used, especially DMSO, diethylenetriamine, and ethylenediamine, and DMSO is more preferable. good.

Examples of the coagulant include alcohols such as methanol, ethanol-di-butanol, acetone, benzene, toluene, etc., mixed solvents of one or more of these and DMSO, saturated free salt aqueous solutions, caustic soda aqueous solutions, etc., but methanol is preferable. , ethanol, and acetone are good.

Further, the distance between the multi-hole nozzle and the coagulation bath liquid level (inert gas atmosphere) is not particularly limited, but is between 3# and 200mm.
s is appropriate; if it is shorter than 3#, it will be difficult to carry out the wet-dry spinning stably, and if it is longer than 200 m, it will be difficult to stabilize the fibrous solution extruded from the nozzle, and a slight The yarn swaying causes problems such as occurrence of 8 pieces between single yarns in this gas atmosphere.

Furthermore, the fibrous solution extruded into this gaseous atmosphere may have a small amount of solvent evaporated, but most of the solvent will be removed in the coagulation bath and subsequent extraction bath. .

On the other hand, in the gel spinning method, as a solvent for the PVA polymer, a solvent is used that heats and dissolves the polymer at high temperature and gels when the resulting solution is cooled, and the solvent is used in the spinneret. When the spinning dope is discharged from the spinning dope and the discharged yarn is cooled, the polymer concentration of the formed gelled yarn is substantially the same as the polymer concentration of the spinning dope before being discharged. The spinning dope needs to be non-volatile under the spinning conditions.

Furthermore, since the PVA polymer itself is thermally decomposed at temperatures above its melting point (approximately 250'C), the solvent should be selected to dissolve at a temperature below the melting point of the PVA polymer. Ru. Examples of such solvents include ethylene glycol, glycerin, diethylene glycol, trimedylolpropane, benzenesulfonamide, and caprolactam.

The cooling liquid that gels the fibrous solution extruded from a multi-hole nozzle is preferably one that has enough movement to cool the solution without changing its polymer composition.
For example, decalin, trichloroethylene, carbon tetrachloride, paraffin oil, kerosene, etc. are preferred. Of course, depending on the cooling temperature, a polymer solvent itself that does not dissolve the fibrous gelled yarn may be used as the cooling liquid.

Incidentally, the distance between the multi-hole nozzle and the liquid surface of the cooling medium bath is the same as in the case of the wet-dry spinning method.

The yarn coagulated or cooled and gelled by the dry-wet spinning or gel spinning is taken off, but this taking-up speed (vl
) is preferably set within a certain range in conjunction with the linear velocity (Vo) of the spinning dope at the nozzle hole. That is, the range is the spinning draft Df expressed by the following formula: Spinning draft (Df)=V1/V□ By setting Df≦1.0, more preferably 0.6≧Df≧0.06, It is possible to keep the orientation low without applying large stress during the solidification process of the yarn, and to improve super-stretchability in the subsequent drawing process. As a result, it becomes possible to draw the yarn at a high magnification as a whole, and a drawn yarn with extremely high molecular chain orientation and extremely high physical properties can be obtained.

In JP-A-59-130314, the spinning draft is 1.7 or more during gel spinning, and as a result, the drawability is low and the yarn properties are also low.

The yarn coagulated by the dry-wet spinning method is subsequently subjected to solvent removal.

On the other hand, the gelled thread cooled by the gel spinning method is subsequently subjected to solvent removal, and finally the solvent is replaced by the extractant used for solvent removal.

The yarn containing the coagulant or extractant thus obtained is sent to a drying process, but it may be slightly stretched in the coagulant or extractant before drying. Rather, it is preferable to stretch this portion in order to reduce the burden on the stretching ratio in the dry one-hot stretching step that follows the drying step.

Further, before starting the drying process, it is preferable to apply an oil to the yarn in order to prevent glue between single yarns during drying.

The dry yarn thus obtained is subsequently hot drawn. Examples of devices used for the hot stretching include various devices using heating tubes, hot plates, heating rolls, heating pins, heated liquids, fluidized beds, etc., but the ultra-high strength of the present invention A heated tube is preferred for obtaining PVA.

Among the above-mentioned hot drawing devices, methods other than heating tubes are methods in which the heating body comes into contact with the yarn, and when drawing the yarn just below its melting temperature, it is difficult to set the temperature delicately. Because the heating efficiency is too high, heat is easily transmitted to the inside of the yarn, and when hot drawing is carried out just below the melting temperature, the yarn may melt or flow may occur within the yarn due to slight fluctuations in the temperature of the heating element, causing This results in problems such as no molecular orientation. On the other hand, in the ultra-stretching method in a non-contact dry heating atmosphere such as in a heating tube, the heating efficiency of the yarn is low, so the yarn is difficult to draw. □ Engineering,
□. Ya Yui, 13 Oi Kou Aii. 5. Can be stretched without curing or flow inside the yarn 1. .

This is preferable because the temperature range can be set relatively wide.
1. Long circumference bright image in X-ray small angle scattering measurement of the present invention
] is not observed and the principal mechanical loss tangent (t
The height of the a (nδ) peak is 0.10 or less. PVA with tensile strength 25q/d or more
In order to obtain a fiber based on fibers, it is preferable to carry out super-stretching at a temperature below the melting point of the yarn in the above-mentioned non-contact dry heating atmosphere.
(Dry-wet spinning method or gel spinning using a PVA-based polymer with a weight average molecular weight of 1 x 106 or more as a raw material)
:・.

Even if a suitable undrawn yarn is obtained by the yarn method, this
;□"If the conditions of the stretching process following 1. are insufficient, the PV of the present invention
j′j゛Δ yarn fibers are not obtained.
□; The internal temperature of the 7” dry heat tube is 150-27
0°C.).

It is set within the range of fI゛1:
! Therefore, the appropriate stretching temperature also becomes higher. For this reason, the yarn is fused and broken.
; 5" temperature is measured in each case as Tl1lb), with reference to this between Tmb-5-0"C and Tmb, preferably between Tmb-30°C and Tmb, more preferably Tmb = 15°C. Set between Tmb.

In order to achieve the present invention, it is necessary to judge whether the drawing temperature is set at an appropriate temperature and whether the degree of super-drawing is sufficient. Principal mechanical loss tangent (tanδ)
The standard is that the peak height is 0°10 or less.

For the dry heat tube, a jacket method using a heating medium is preferable because the temperature is stable. Furthermore, it is preferable to flow heated air or inert gas into the tube along with the yarn.

Furthermore, multistage stretching is preferred, and a heat treatment step may be added in the final stage if necessary.

The total draw ratio throughout the entire process should be as high as possible, i.e. 2, for example, 80% or more of the draw ratio at which yarn breakage occurs,
Alternatively, it is preferably 85% or more, and the X of the yarn after drawing is
When measuring small-angle line scattering.

It is preferable to carry out stretching until a long-period image is no longer observed. In this case, the yarn to be drawn should be limited to a thickness such that the single filament fineness of the yarn after drawing is 5 deniers, preferably 2 deniers or less. If the denier exceeds 5 denier, it becomes difficult to obtain the ultra-high strength fiber of the present invention. In other words, the thinner the single filament fineness, the more the fiber structure remains in the cross-sectional direction from the solidification process after spinning to the hot drawing process. It is thought that it is easy to become homogeneous, and from the viewpoint of material mechanics, the probability of containing defects is reduced, resulting in high strength.

[Effect of the invention] The ultra-high strength P, VA fiber of the present invention has a tensile strength of 25
Due to its extremely high physical properties, exceeding the AID, it is used in tire cords, seat belts, general rubber reinforcement materials, ropes
Very useful for cables, industrial coated fabrics, slings, sail cloths, resin reinforcements, concrete reinforcements, industrial sewing threads, fishing nets, etc., making these products finer and thinner.

Since it can be made lighter, it can be used in a way that is significantly different from conventional methods.

[Example] Hereinafter, the effects of the present invention will be specifically explained with reference to Examples.

In this example, tensile strength, small-angle X-ray scattering, mechanical loss tangent (t
anδ) was measured according to the following method.

a. Using a fiber made of tensile strength multifilament yarn as a sample,
It was measured according to the test method specified in J15-L-1017. That is, the fibers are wound into a skein, and
After leaving it in an atmosphere adjusted to 265% RH for 24 hours, a sample was taken from this side and "'Tensilon"
UTM-41 type tensile testing machine [Toyo Baldwin Co., Ltd.]
The sample length was 25 cm, and the tensile speed was 30 cm for 1 minute.

b. Small-angle X-ray scattering Measured according to a known method using a Kiessiq Camera. The following conditions were set as measurement conditions.

An RU-200 X-ray generator manufactured by Rigaku Denki Co., Ltd. was used.

CIJ Kα ray (using Ni filter), output: 50K
V -150mA, 0.38Φ collimator used, transmission method, camera radius: 400m, exposure time: 90 minutes, film: Kodak no screen type.

C9 Mechanical loss tangent (tan δ) Using Pyblon DD-n type manufactured by Toyo Baldwin Co., Ltd., the main dispersion (C
a) Measure the peak height under the following conditions, and calculate t using the following formula.
An δ was calculated.

Measurement conditions: Number of imaging: 110H, heating rate: 3°C/min Sample length: 4cm Atmosphere: In air <23°C, 50% R11> Calculation formula: % formula % E-; Storage modulus (dyne/denier )E″; Loss modulus (dyne/denier) Example 1 Completely saponified PVA (saponification degree of 99.5% or more) with a weight average molecular weight (MW) of 1.2×106 was dissolved in DMSO
was dissolved at 110°C to prepare a spinning stock solution with a P and VA concentration of 8% by weight.

The spinning stock solution was discharged from a spinneret with a hole diameter of 0.10 mm and a number of holes of 50 into a methanol coagulation bath containing 100 weight of DMSO, and wet-dry spinning was performed.

The distance between the spinneret surface and the coagulation bath liquid level was set to Bmm, the total amount of spinning stock solution discharged from the spinneret was 26.2 ccZ, and the coagulated yarn was taken off at a rate of 10 m/min.

At this time, the spinning draft (Df) is 0.15.

After thoroughly washing the coagulated thread with methanol,
The film was stretched 4 times in a methanol bath, coated with an oil agent, and dried using a hot roll with a surface temperature of 60°C. The dried yarn was then further stretched 5.5 times at 240° C. in a 3 m long heating tube. At this time, the yarn feeding speed is 1
m/min, and nitrogen gas heated to 240°C was flowed through the heating tube in the running direction of the yarn. The obtained drawn yarn had the following physical properties.

Fineness: 93.7d (Single yarn 1.87d> Tensile strength: 26.3 (]/d Cutting elongation;
3.8% Long-period image; unobserved tan δ peak height; O, Oa Comparative Example 1 In Example 1, when the dry yarn was stretched with a heating tube, when the stretching temperature was set to 225°C, the maximum stretching ratio was 4 ．．
The resulting drawn yarn had the following physical properties.

Fineness: 110 d Tensile strength;
19.6 g/d breaking elongation; 4.6% Long-period image; Observed (185 people) tan δ peak height; 0.12 Comparative Example 2 In Example 1, the dry yarn was not heated in a heating tube, When drawn with a hot plate having a length of 1 m, the maximum drawing ratio was 4.9 times at 225° C., and the obtained drawn yarn had the following physical properties.

Fineness: 104d Tensile strength: 20.1 g/d Cutting elongation:
4.7% Changzhou Ming image; Observed (197 people) tan δ peak height; 0.11 Example 2 Completely saponified type with weight average molecular weight (MW>2.2X106) (degree of saponification 99.8%) Above) PVA was dissolved in glycerin at 215°C to prepare a spinning stock solution containing 6% by weight of PVA 1 degree.

The spinning stock solution was extruded from a spinneret with a hole diameter of o, 2 omm, and 20 holes through a 12 mm air layer into a decalin cooling bath at 12°C, and gel spinning was performed.

The total discharge rate of the spinning dope from the spinneret was 13.6 CC/min, and the cooled gel yarn was taken off at 5 m/min.

At this time, the spinning draft (Df>) is 0.23.

The collected glue threads were stretched four times in a Kano tube at an internal temperature of 100°C, and then thoroughly washed with methanol.
Dry. Next, the dried yarn was heated in a heating tube with a length of 3 m under the same conditions as in Example 1 for 6. "The drawn yarn was drawn twice. The drawn yarn had the following physical properties.

Fineness: 64.2 d II
Tensile strength: 29.4 g/d Cutting elongation:
3.8% long-period image; unobserved tanδ peak height: 0.07
(Comparative Examples 3 and 4, Example 3 Weight average molecular weight (MΔ) is 1.6X10, 3.
74X10. Completely saponified type with 1.1X106
1'2).

PVA, PVla degree is 17.13.9 weight respectively
A spinning stock solution of .
□1゛1 The pulling speed was 5 m/min, and the pulled gel thread 1:, :1, was similarly stretched 4 times, and after solvent removal, it was drawn in a heating tube.
″：Pa、：、 Hot stretched.The highest value of the hot stretching ratio at this time and
□[゛The physical properties of the drawn yarn are shown in Table 1.

Table 1

Claims (2)

[Claims] (1) 25 g/d consisting of a polymer that is essentially polyvinyl alcohol and has a weight average molecular weight of 1 x 10^6 or more
Ultra-high strength polyvinyl alcohol fiber with tensile strength of (2) The ultra-high intensity according to claim 1, wherein no long-period image is observed in small-angle X-ray scattering measurement, and the height of the main mechanical loss tangent (tan δ) peak is 0.10 or less. Polyvinyl alcohol fiber.