JPH08199426A - Highly strong polyamide fiber and its production - Google Patents

Abstract

PURPOSE: To obtain the subject fiber having a sufficient high strength level, suitable as a fiber for reinforcing rubbers, a fiber for fishing nets, etc., and having a high strength and a high toughness by spinning a polyamide composition containing a higher alkylamide compound under specific conditions and subsequently drawing the spun fiber under specified conditions. CONSTITUTION: This method for producing a highly strong polyamide fiber comprises melt-spinning a polyamide composition containing a higher alkylamine and an alkyldicarboxylic acid, or a higher alkylamine compound (e.g. ethylene bisstearyl amide) obtained from a higher fatty acid and an alkyldiamine in an amount of 0.01-2wt.% and having a sulfuric acid relative viscosity of >=3.0 at a spinning temperature of 280-310 deg.C, gradually cooling the spun fiber in a heating cylinder heated at >=250 deg.C and disposed just under the spinneret, rapidly quenching the fiber for solidifying the fiber, imparting an aqueous emulsion oil to the solidified fiber, and subsequently heat-drawing the fiber. The obtained fiber has following fiber structure parameters: (1) birefringence: Δn >=55×10<-3> ; (2) differential birefringence: δΔn<=-2×10<-3> ; (3) crystal orientation degree: fc >=0.88; (4) amorphous molecular orientation degree: fa=0.70-0.85; (5) main distribution peak temperature <=113 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength polyamide fiber and a method for producing the same, and particularly to a high-strength polyamide fiber having high strength and high toughness, which is suitable as a rubber-reinforcing fiber and / or a fishing net fiber, and this high-strength polyamide fiber. The present invention relates to a method for producing a high-strength polyamide fiber by an efficient process.

[0002]

BACKGROUND OF THE INVENTION Polyamide fibers are excellent in toughness, adhesiveness and fatigue resistance, so that they are used in various industrial materials such as tire cords, conveyor belts, transmission belts, rubber reinforcing cords such as rubber hoses, fishing nets, It has been widely used for various industrial applications such as ropes, safety belts, slings, tarpaulins, tents, braids, and sewing threads.

Polyamide fiber, especially when used as a rubber-reinforcing cord, is strong against thermal and mechanical stimuli received in a twisting process, a heat setting process after applying an adhesive and a rubber vulcanization process. There are demands for retaining properties and strong retaining properties against repeated fatigue during tire running, and many studies have been made to satisfy these required properties. For example, JP-A-54-150
No. 22, Japanese Patent Laid-Open No. 55-45863, and Japanese Laid-Open Patent Publication No. 1-168915 have been proposed.

That is, in the prior arts disclosed in JP-A-54-15022 and JP-A-55-45863, an aqueous emulsion oil agent is used as a spinning oil agent, and an aqueous drawing agent is used for an undrawn yarn. Immediately after applying the emulsion oil, spray the fluid with the confounding nozzle,
This is a method in which an oil agent is uniformly migrated to each filament of a polyamide unstretched yarn, and then hot stretching is performed. By such a method, a polyamide fiber having high strength of 10 g / d or more and excellent fatigue resistance can be obtained. It is said that.

Further, the technique disclosed in the above-mentioned JP-A-1-168915 discloses that the surface layer of each filament is uniformly treated by passing through a steam atmosphere immediately before applying the oil agent to the polyamide undrawn yarn. A method in which an oil agent is applied and then hot drawing is performed, and by such a method, 10 g / d
It is said that a polyamide fiber having the above high strength, improved strength retention in the tire cord processing step, and excellent fatigue resistance can be obtained.

That is, in each of the above-mentioned prior arts, the unstretched yarn of polyamide fiber is uniformly given water and then hot-stretched to obtain high strength, strong holding property and fatigue resistance. It is characterized by obtaining excellent polyamide fibers.

[0007] As described above, the polyamide fiber can be provided with physical properties excellent in tenacity retention and fatigue resistance by imparting water in the yarn making process, particularly in the stage of the undrawn yarn, and then hot drawing. , And that a stable fiber structure that contributes to the expression of the physical properties is formed.

The term "stable fiber structure" means that the change in fiber structure is small when subjected to thermal or mechanical stimulation during the tire cord processing step or tire running.

However, conventional polyamide fibers are
By imparting water at the stage of the undrawn yarn, the stable fiber structure as described above is formed and excellent strength retention and fatigue resistance are obtained, but it is difficult to obtain the desired high strength characteristics. Had.

That is, a general process for stably producing high strength polyamide fibers of 10 g / d or more is as follows:
For example, JP-A-59-187617 and JP-A-5-187
As disclosed in Japanese Patent Publication No. 8-115114 and the like,
It is a process of hot drawing without applying water to the undrawn yarn, specifically, a method of applying a non-aqueous oil agent and then hot drawing.

Since the polyamide fibers obtained by the above method are generally insufficient in terms of strength retention and fatigue resistance, in the yarn making process and tire cord processing process, for example, sufficient heat treatment after hot drawing. Other techniques, such as a method of applying heat treatment, a method of strengthening heat setting after application of an adhesive in the tire cord processing step, and a method of improving strength retention and fatigue resistance by selecting an appropriate oil agent or adhesive. In fact, it is improved to a practically sufficient level by combining improvement means.

On the other hand, as a method for obtaining a polyamide fiber having high strength and excellent strength retention and fatigue resistance,
There is a method of uniformly applying water to the above-mentioned undrawn yarn,
With this method, a sufficiently high strength cannot be obtained.

The reason why it is difficult to obtain a high-strength yarn by adding water to the undrawn yarn is considered to be as follows.

The first reason is that the water-permeated portion is more likely to crystallize during hot stretching than the other portions, and the molecular chains are less likely to be oriented, and the insufficiently oriented portion does not contribute to strength. Therefore, the greater the degree of water penetration, the lower the degree of molecular chain orientation and the lower the strength.

The second reason is that when water is applied to the undrawn yarn, the water penetration between the filaments of the yarn and in the cross section of the filaments varies, and this causes the fiber structure and physical properties between filaments. In this case also, sufficient orientation of the molecular chains cannot be achieved, and a high strength yarn cannot be obtained.

Therefore, in order to achieve an ideal high strength, water permeates uniformly between filaments and within the cross section of the filament, and permeates from the surface of the filament to a proper depth, for example, 1 to 5 μm. This can be confirmed by observing the cross section of the filament under a polarizing microscope and observing the water permeated portion as a surface crystal layer.

From the above, the polyamide fiber having high strength and excellent strength retention and fatigue resistance can be formed by uniformly imparting water to the undrawn yarn so that it is uniformly permeated between the filaments and in the filament cross section. , And can be obtained by permeating to a depth of 1 to 5 μ.

[0018] In spite of this, melt spinning is carried out, spinning from the spinneret,
Since the solidified polyamide undrawn yarn is in an absolutely dry state,
When an aqueous emulsion oil was added to this, water was absorbed instantly, and it was not possible to uniformly permeate water between the multifilaments and inside the filament cross section.

Therefore, the above-mentioned Japanese Patent Laid-Open No. 54-15022.
According to the conventional techniques disclosed in JP-A-55-45863 and JP-A-55-45863, a method of migrating the aqueous emulsion oil agent between filaments by applying entanglement treatment with a fluid immediately after applying the aqueous emulsion oil agent Water is relatively evenly distributed between the filaments, and as a result, high strength up to about 9.6 g / d is obtained, but uniform penetration of water into the filament single yarn cross section is sufficiently controlled. As a result, it was difficult to stably obtain a high-strength polyamide fiber of 10 g / d or more.

On the other hand, in the method disclosed in Japanese Patent Laid-Open No. 1-168815, it is sure that the water is evenly permeated between the filaments and inside the filament, and the permeation depth of the water into the filament single yarn cross section is also increased. , Stee
It can be controlled by processing conditions, resulting in 10g /
Although a polyamide fiber having a high strength of d or more and excellent strength retention and fatigue resistance can be obtained, this method has a drawback that installation of a steam treatment cylinder and its process control are complicated.

[0021]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The present invention has been studied as an object to improve the above-mentioned drawbacks of the prior art.
It has been achieved.

Therefore, an object of the present invention is to provide a high strength polyamide fiber having a sufficiently high strength level and particularly suitable as a rubber-reinforcing fiber and / or a fishing net fiber, and a high-strength polyamide fiber, and this high-strength polyamide. It is an object of the present invention to provide a method for producing fibers by a simple and efficient process using an aqueous emulsion oil agent.

[0023]

In order to achieve the above object, the high-strength polyamide fiber of the present invention contains a higher alkylamide compound and melts a polyamide composition having a sulfuric acid relative viscosity of 3.0 or more. A polyamide fiber obtained by spinning and drawing, which is characterized by having the following fiber structure parameters (a) to (e). (A) Birefringence (Δn): Δn ≧ 55 × 10 ⁻³ (b) Differential birefringence (δΔn = Δna−Δnc): δΔn
≦ −2 × 10 ⁻³ (however, Δna: birefringence at a position of 0.95 from the center to the surface, Δnc: birefringence at the center) (C) Crystal orientation degree (fc): fc ≧ 0.88 (d) Degree of orientation of amorphous molecules (fa): fa = 0.70-0.
85 (e) Mechanical tangent loss (ta
nδ) Main dispersion peak temperature (Tα) on the curve: Tα ≦
113 ° C.

The high-strength polyamide fiber of the present invention is
It is characterized by containing 0.01 to 0.2% by weight of a higher alkylamide compound.

Furthermore, the high-strength polyamide fiber of the present invention is characterized in that it is a multifilament having a single yarn number of 100 denier or less and a single yarn number of 20 or more.

Furthermore, the high-strength polyamide fiber of the present invention has a strength of 10.0 g / d or more, a cutting elongation of 20% or more, and a boiling water shrinkage ratio of less than 12.0%, and is particularly suitable for rubber reinforcement applications. Characterized by suitability or strength of 8
g / d or more, cutting elongation of 25% or more, boiling water shrinkage rate of 1
It is 0% or more, and is particularly suitable for fishing net applications.

The high-strength polyamide fiber production method of the present invention comprises adding a higher alkylamide compound in an amount of 0.01-2.
By weight, and melt-spinning a polyamide composition containing sulfuric acid at a relative viscosity of 3.0 or more at a temperature of 280 to 310 ° C.,
The spun yarn is gradually cooled in a heating cylinder at 250 ° C. or higher placed directly below the spinneret, and then rapidly cooled and solidified. Then, an aqueous emulsion oil agent is applied to the cooled yarn, and subsequently, hot drawing is performed to obtain the above ( A) to produce a high-strength polyamide fiber having the fiber structure parameters of (e) to (e).

Further, in the method for producing a high-strength polyamide fiber of the present invention, the aqueous emulsion oil agent contains a smoothing agent and an activator as essential components, and the birefringence of the undrawn yarn is 2
It is in the range of × 10 ^{−3 to} 20 × 10 ⁻³ , the final stretching temperature during stretching is 210 ° C. or higher, and the total stretching ratio is 3.
It is characterized by being 5 to 6.5.

The present invention will be described in detail below.

The polyamide fiber of the present invention is made of a polyamide containing polycapramide (nylon 6), polyhexamethylene adipamide (nylon 66), and polytetramethylene adipamide (nylon 46) as main components. However, these material polyamides may be copolyamides containing 5% by weight or less of a copolymerization component with respect to the polyamide.

Examples of the copolymerization component used in the present invention include ε-caproamide, tetramethylene adipamide, hexamethylene sebacamide, hexamethylene isophthalamide, tetramethylene terephthalamide, xylylene phthalamide and the like. Is mentioned. Here, when the content of the copolymerization component is 5 mol% or more, the crystallinity of the obtained polyamide fiber is lowered, and heat resistance and thermal dimensional stability tend to be impaired, which is not preferable.

The high strength polyamide fiber of the present invention is a fiber composed of a high molecular weight polyamide polymer having a sulfuric acid relative viscosity of 3.0 or more, preferably 3.2 or more. Here, when the relative viscosity of sulfuric acid of the polyamide is less than 3.0, the high-strength and / or high-toughness polyamide intended by the present invention cannot be obtained.

The polyamide fiber of the present invention has a single yarn fineness of 1
It is a fiber composed of multifilaments having a denier of less than 00 and a single yarn number of 20 or more. Preferably the single yarn fineness is 50
It is a multifilament fiber that is less than denier and has 30 or more single yarns, and is usually suitable for rubber material applications such as tire cords, belts and hoses and / or fishing net applications.

It is important that the polyamide fiber of the present invention contains 0.01 to 0.2% by weight of a higher alkylamide compound.

The higher alkylamide compound used in the present invention is a compound obtained from a higher fatty acid and an alkyldiamine, or a higher alkylamine and an alkyldicarboxylic acid, and specific examples thereof include ethylenebisstearylamide and Ethylenebislaurylamide,
Examples include distearyl adipamide, dilauryl sebacamide, and the like.

The effect of containing the higher alkyl amide compound is that when the polyamide polymer is melted, spun through the pores of the spinneret, and then the water-based emulsion oil agent is applied to the yarn that has been solidified by cooling, the water becomes a filament. The purpose is to prevent rapid penetration into the interior.

That is, the higher alkylamide compound is
When added to polyamide and melt-spun, it migrates to the surface layer of the filament during the cooling and solidification process,
The concentration becomes high in the surface layer portion, and since this hydrophobic higher alkyl compound covers the surface layer of the polyamide, rapid penetration of water into the polyamide filament is suppressed.

As a result, even if the water-based emulsion adheres to the polyamide yarn immediately after cooling and solidification, water does not permeate into the filaments instantaneously, so that water permeates uniformly between filaments and within the cross section of the filaments. It becomes possible to do it.

The content of the higher alkylamide compound in the material polyamide is 0.01 to 0.2% by weight,
It is preferably 0.02 to 0.1% by weight. When the content of the higher alkylamide compound is 0.01% by weight or less, the effect of suppressing water permeation is insufficient. Further, if the content of the higher alkyl amide compound is 0.2% by weight or more, the permeation suppressing effect is too strong, and although high strength yarn can be obtained as in the case where the non-aqueous oil agent is applied, the tenacity retention and fatigue resistance are obtained. This is not preferable because the effect is insufficient. Also, 0.5% by weight
Excessive addition over 10 is not preferable because it causes problems such as a decrease in strength and a decrease in dimensional stability.

Next, the basis for specifying each fiber structure parameter that characterizes the high-strength polyamide fiber of the present invention will be described.

The birefringence Δn is 55 × 10 ^-3 or more, preferably 58 × 10 ^-3 or more, which is highly oriented. The birefringence of the polyamide fiber of the present invention is 8.0 g / d or more, preferably 1
This is an alignment property required to achieve a high strength of 0 g / d or more.

The differential birefringence δΔn (= Δna-Δnc) is −2 × 10 ⁻³ , and the birefringence of the filament surface layer portion is lower than that of the central portion by 2 × 10 ⁻³ or more. Preferably from 2 × 10 ⁻³
It is characterized by 6 × 10 ⁻³ lower. Birefringence is 2 × 10 ^-3
The lower surface layer has a thickness of 1 to 10 µ, preferably 2 to 6
is μ. The value of the differential birefringence exceeds -2 × 10 ^-3 ,
When the thickness of the surface layer portion is less than 1 μ, the strength retention and fatigue resistance, which are the effects of the present invention, become insufficient. On the other hand, when the thickness of the surface layer portion is too thick, for example, more than 10 μ, the obtained polyamide is obtained. It is difficult to achieve a high strength of 8.0 g / d or more, preferably 10 g / d or more, which is not preferable.

The degree of crystal orientation fc is 0.88 or more, which is almost the same as that of ordinary high strength polyamide fiber, and this parameter also characterizes the high strength polyamide fiber of the present invention.

The degree of orientation fa of amorphous molecules is 0.70 to 0.85.
Is. This degree of amorphous molecular orientation is the average degree of orientation of the relatively highly oriented amorphous molecular chains in the inner layer that occupy most of the polyamide filament and the low orientation amorphous molecular chains between the crystal layers in the surface layer. Shows.

The main dispersion peak temperature Tα in the mechanical tangent loss curve obtained by dynamic viscoelasticity measurement is characterized by a relatively high value of 113 ° C. or higher. At this main dispersion peak temperature, the orientation of the amorphous molecular chains in the inner layer portion, which occupies most of the polyamide filament, is high, the crystallinity is also relatively high, and the movement of the molecular chains in the amorphous portion is relatively restricted. It is shown that.

The high strength polyhexamethylene adipamide fiber of the present invention has the above fiber structure parameters (a) to (e).
Is a novel fiber characterized by. Since the fiber structural parameters (a) to (e) are closely related to each other, it is necessary to satisfy them at the same time.

The high strength polyamide fiber of the present invention satisfying the above fiber structure parameters has a strength of 10.0 g / d.
Above, cutting elongation is 20% or more and boiling water shrinkage is 1
It has a physical property of less than 0.0%, a strength of 8 g / d or more, a cutting elongation of 25% or more, and a boiling water shrinkage rate of 10% or more.

That is, the strength is 10.0 g / d or more, the cutting elongation is 20% or more, and the boiling water shrinkage is 10.0%.
Polyamide fibers of less than 10% have optimum properties mainly for rubber-reinforcing applications, and have a strength of 8 g / d or more, a cutting elongation of 25% or more, and a boiling water shrinkage rate of 10% or more, It has optimal characteristics mainly for fishing net applications.

Since the high-strength polyamide fiber of the present invention is preferably used for industrial materials such as rubber reinforcing materials and fishing nets, in order to impart heat resistance, weather resistance and oxidation resistance, an antioxidant is usually used. It is desirable to be added.

The antiaging agent used in the present invention includes:
Copper compounds and organic or inorganic phosphorus compounds, alkali metal or alkaline earth metal halides, quaternary ammonium halides, diphenylamine antioxidants, 2-mercaptobenzimidazole, hindered phenolic antioxidants and the like. To be

Specific examples of the above copper compound include cupric acetate, cuprous iodide, cupric chloride, cuprous bromide, cupric bromide, copper phthalate, copper stearate, and copper phosphate. , Copper pyrophosphate, and complex salts of various copper salts with inorganic or organic compounds.

The amount of copper compound contained in the polyamide fiber is 30 to 150 ppm, preferably 50 to 100 ppm as copper, and the content of the antioxidant used in combination with the copper compound is 0.01 to 0. 0.5% by weight, preferably 0.05 to 0.2% by weight.

Next, a specific example of the method for producing the high-strength polyamide fiber of the present invention will be described.

First, 0.01% higher alkyl amide compound is added to a polyamide polymer having a sulfuric acid relative viscosity of 3.0 or more.
A polyamide composition is prepared by adding, if necessary, a copper compound as an antioxidant and an alkali metal halide to the composition added by 0.2 wt%.

Next, the above polyamide composition is dried to a water content of 0.2% by weight or less, and then melted at a spinning temperature of 280 to 310 ° C. using an extruder type spinning machine.

The molten polymer is then placed in a spin pack,
After filtering through a metal non-woven fabric filter having pores of about 5 to 50μ, it is spun through the spinneret pores.

A heating cylinder having a length of 10 to 100 cm, preferably 15 to 50 cm is installed immediately below the mouthpiece, and the atmosphere temperature in the heating cylinder is 250 ° C. or higher, preferably 280 to 310 ° C.
And

The yarn that has been slowly cooled by passing through the heating cylinder atmosphere is then blown with cold air to be rapidly cooled and solidified.

Next, an aqueous emulsion oil agent is applied to the yarn. The components of the water-based emulsion oil agent used here consist of a leveling agent, an activator and an additive.The leveling agent is mainly a component that reduces the frictional resistance between the yarn and the metal in the spinning process, and the activator is mainly Contains components that improve the emulsifying action to make the oil agent a stable emulsion and the higher-order processability of the polyamide fiber, such as adhesion and fatigue resistance.Additives are antistatic agents, extreme pressure agents and heat resistant agents. Including ingredients such as.

In the method for producing high-strength polyamide fiber according to the present invention, when the water-based emulsion oil agent is applied and then heat-stretched, the polyamide fiber is 0.01 to 0.2.
By containing the weight% of the higher alkyl amide compound, the obstacles associated with the application of the aqueous emulsion oil agent are improved.

That is, when the water-based emulsion oil agent is applied to the polyamide unstretched yarn, it becomes difficult for water to permeate the inside of the filament instantaneously, so that the water permeates uniformly into the surface layer of the filament, and There is less variation in the water penetration between the filaments.

As a result, the stretchability is also improved, and polyamide fibers having high strength and high toughness can be obtained.

For the purpose of obtaining the effect of the present invention more remarkably, it is preferable to use a component that suppresses the permeation of water into the polyamide filament as the component of the aqueous emulsion oil agent, especially the activator component.

As a concrete example of this activator component, for example, a compound having a large hydrophobic group and / or a reactive group which easily absorbs water as a hydrate is effective.
/ POP-Sorbitan triisostearate, POE
(24) Trimethylolpropane distearate, PO
E (20) hydrogenated castor oil trioleate, and POE /
POP-2 ethylhexanol and the like are preferable.

The amount of the above-mentioned water-based emulsion oil agent attached to the polyamide fiber is 0.3 to 0.3 as a solid content (oil content).
1.5% by weight, preferably 0.5-1.2% by weight
Is.

The polyamide yarn to which the above-mentioned water-based emulsion oil agent was applied was 300 to 1000 m / in a take-up roll.
Min, preferably 450 to 800 m / min, and the drawn yarn is continuously sent to the stretching step without being once wound and used for stretching.

The condition of the heating cylinder and the take-up speed must be set in relation to each other, but the birefringence of the undrawn yarn is 2 × 10 ^{−3 to} 20 × 10 ⁻³ , preferably Is preferably in the range of 3 × 10 ⁻³ to 15 × 10 ⁻³ .

As for the stretching, a multi-stage hot stretching of two or more stages is adopted, but 90% or more of the critical stretching ratio, preferably 92 to 96.
Stretch in the range of%. Here, the limit draw ratio is the maximum draw ratio that can be drawn for 5 minutes or more without yarn breakage.

The total draw ratio is 3.5 to 6.5 times, usually 4.0 to 6.0 times. Further, it is desirable that the stretching temperature is a high temperature of 210 ° C. or higher, preferably 215 to 250 ° C., as the final stretching temperature.

Further, a heat relaxation treatment is carried out subsequent to the stretching, and this heat treatment is usually carried out under the condition of a relaxation of 5 to 15%, preferably 8 to 12% between the final stretching roll and the relaxing roll arranged thereafter. Done in.

The high-strength polyamide fiber of the present invention obtained by the above method has the above-mentioned fiber structure parameters (a) to
(E) and has fiber properties.

The high-strength polyamide fiber of the present invention has high strength and high toughness, and particularly has a strength of 10.0 g / d or more, a cutting elongation of 20% or more, and a boiling water shrinkage ratio of 1.
A polyamide fiber content of less than 0.0% is a fiber for reinforcing a rubber, and when it is embedded in rubber and subjected to a vulcanization treatment, the strength is not significantly reduced, and a vulcanized cord having a high strength is obtained.

When such a high-strength vulcanized cord is used, the number of cords used as a tire reinforcing material can be reduced, and the number of woven fabrics having a sloping shape can be reduced. Alternatively, it is possible to use a cord in which the fineness of the fiber is reduced in advance. In any case, the weight of the fiber can be reduced without impairing the reinforcing function, and the weight reduction of the tire can be achieved.

Further, the strength is 8 g / d or more and the cutting elongation is 2.
When used as a fishing net fiber, polyamide fiber having a boiling water shrinkage ratio of 5% or more and a boiling water shrinkage ratio of 10% or more has high durability due to its high toughness and also has good transparency. It is the most suitable raw yarn for use.

Further, according to the method for producing high-strength polyamide fiber of the present invention, a low-viscosity mineral oil is used as a diluent for an oil crude oil like a non-aqueous oil agent which has been conventionally used for producing high-strength polyamide fiber. Since it is not necessary, there is a merit that the basic unit of the oil agent is lowered, and further, there is an advantage that it is advantageous in disaster prevention because a low-viscosity mineral oil having a relatively low boiling point is not used.

[0076]

The present invention will be described in more detail with reference to the following examples.

The definitions of the fiber structure parameters, fiber physical properties, tire cord properties, etc., and the measuring methods described in the examples are as follows.

(1) Sulfuric Acid Relative Viscosity (ηr) 2.5 g of a sample was dissolved in 25 cc of 98% sulfuric acid and measured at 25 ° C. using an Ostwald viscometer.

(2) Birefringence (Δn) The birefringence was measured by a Berek compensator method using a POH type polarization microscope manufactured by Nippon Kogaku Co., Ltd. and white light as a light source.

(3) Differential Birefringence (δΔn = Δna-Δnc) It was measured by an interference fringe method using a transmission quantitative interference microscope manufactured by Carl Zeiss Jena (East Germany). The birefringence at a position of 0.95 from the center to the surface was set as Δna, and the birefringence of the central part was set as Δnc.

(4) Density (ρ) Measurement was carried out at 25 ° C. by a density gradient tube method using toluene as a light liquid and carbon tetrachloride as a heavy liquid.

(5) Crystal Orientation Degree (fc) Using an X-ray generator (type 4036A2) manufactured by Rigaku Denki Co., Ltd., CuKα (using a Ni filter) was measured as a radiation source (output 35 KV, 15 mA, slit 2 mm).
φ). Half-value width H of the intensity distribution obtained by scanning the (100) plane observed in the vicinity of 2θ = 20.6 ° in the circumferential direction
It was calculated from ° using the following formula.

Fc = (180 ° -H °) / 180 ° (6) Amorphous molecular orientation (fa) Using the values of the crystallinity and the crystal orientation determined from birefringence and density, the following RSS Stein et al. , J. Polymer Sci., 21,
It was calculated from the formula of 381, (1956).

= XfcΔ ° c + (1-X) fa where Δ: birefringence X: crystallinity fc: crystal orientation degree fa: amorphous molecular orientation degree Δ ° c: intrinsic birefringence of crystal part Δ ° a: Intrinsic birefringence of the amorphous part (Δ ° c = Δ ° a = 0.73) (7) Main dispersion peak temperature (Tα) in the mechanical tangent (tan δ) curve “Vibron DDV” manufactured by Orientec Co., Ltd. -I
The measurement was performed in an air bath (23 ° C., 50% rh) at a frequency of 110 HZ and a heating rate of 3 ° C./min.

(8) Strength (T / D), Elongation (E), Intermediate Elongation (ME) Using a "Tensilon UTL-4L" type tensile tester (manufactured by Orientec Co., Ltd.), JIS L- 1017,
It was measured according to 7.5.

The intermediate elongation is 5.36 × D / 1000 kg for the raw yarn and (5.36 × D) for the cord in the load-elongation curve.
The elongation was D × n) / 2 × 1000 kg. (Here, D: fineness of the original yarn, n: number of original yarns made by ply yarn) (9) Shrinkage rate of boiling water (ΔS ^w ) Measured according to JIS L-1017, 7.14.

(10) Dry heat shrinkage (ΔSD) The dry heat shrinkage was measured according to JIS L-1017, 7.10.2B. The measurement temperature is 177 ° C.

(11) GY Fatigue Life Measured according to JIS L-1017, 3.2.2.1A.

(12) Strength retention after vulcanization The dip cords are arranged in parallel with the unvulcanized rubber sheet, set in a mold together with another unvulcanized rubber sheet, and then 175
It was vulcanized for 30 minutes by a heat press machine set at ° C. Immediately after taking out the mold from the heat press machine, the mold was water-cooled to rapidly and freely shrink the cord in the rubber. Then take out the cord from the rubber sheet, 20 ℃, 65%
The strength of the vulcanized cord was measured after leaving it in the temperature and humidity control room of RH for 24 hours or more, and the ratio to the strength of the cord before vulcanization was obtained.

[Examples 1 to 3, Comparative Examples 1 to 7] Example 1
~ 3 is 0.01% by weight of copper acetate, 0.1 potassium iodide
% Nylon, 0.1% by weight potassium bromide, and nylon 6 chips with a relative sulfuric acid viscosity of 3.7 with the addition of ethylenebisstearylamide in the proportions shown in Table 1 were spun on an extruder spinning machine.

The discharge amount was adjusted so that the total yarn fineness was 1260D. The mouthpiece has a hole diameter of 0.3 mm and a number of holes of 306.
The polymer temperature was 280 ° C. A 10 μ-cut non-woven fabric filter was used for filtration.

The spun yarn was placed directly below the spinneret, and the atmosphere was sealed with nitrogen gas at 5 Nl / min and passed through a heating cylinder having a length of 25 cm kept at 300 ° C., and then through a heat insulating zone having a length of 5 cm. The uniflow chimney with a length of 90 cm attached was passed through to quench. Chimney style is 20 ℃,
The condition was 30 m / min.

After that, by the oil supply device arranged in two stages,
Aqueous emulsion oil (first step) and non-aqueous oil (2
Steps) are added. The oil agent contains dioleoyl adipate as a main component and an activator of POE (24) trimethylolpropane distearate and POE (20) hydrogenated castor oil trioleate.

The amount of the oil agent applied was 0.5% by weight of the aqueous emulsion oil agent to the yarn in the first step, and 0.5% by weight of the non-aqueous oil agent to the yarn in the second step. .

Next, the yarn is taken up by a take-up roll rotating at a predetermined speed, and then stretched by 5% between the first supply roll and the second supply roll heated to 40 ° C.
1-stage stretching with the first stretching roll heated to 70 ° C., 2
Two-stage stretching with the second stretching roll heated to 00 ° C, three-stage stretching with the third stretching roll heated to the temperature (final stretching temperature) shown in Table 1 and stretching shown in Table 1. Magnification,
Further, the film was relaxed and wound between a third stretching roll and a relaxing roll heated to 140 ° C.

In Comparative Examples 1 to 4, the spinning conditions were changed as shown in Table 2, and in Comparative Examples 5 to 7, commercially available nylon 6 raw yarns for tire cords were obtained and evaluated. The result.

Tables 1 and 2 also show the evaluation results of the structural parameters and fiber physical properties of the polyamide fibers and the commercially available nylon 6 raw yarn obtained above.

In Tables 1 and 2, "oil 1
The symbols a and b of "stage / 2 stage" have the following meanings. a: Water-based emulsion oil agent (first step) / non-aqueous oil agent (second step) b ... Non-aqueous oil agent (first step) / non-aqueous oil agent (second step) ~
For comparison Further, each polyamide fiber obtained above was subjected to undertwisting 39 times per 10 cm, and then two cords were put together from below, and the same number of overtwist was applied in the opposite direction to the undertwisting. It was a raw code.

An adhesive was applied to each of the raw cords by using a “Computerator” dipping machine manufactured by Ritzler Co. (US), and subsequently heat-treated. An RFL liquid was used as the adhesive, and the liquid concentration and the liquid draining conditions were adjusted so that the adhesion amount was about 5% by weight.

The heat treatment condition is that the drying zone is 160 ° C. for 1 hour.
After passing a fixed length for 20 seconds, a heat treatment zone at 235 ° C. was stretched for 40 seconds so that the stress (value obtained by dividing the tension by the fineness of the dip cord) at the exit of the heat treatment zone was 1 g / d. . Then, in the normalizing zone, heat treatment was applied at 230 ° C. for 40 seconds while giving 1% relaxation.

The characteristics of the obtained dip cord as a tire cord were measured, and the results are also shown in Tables 1 and 2.

[0102]

[Table 1]

[Table 2] As is clear from the results in Tables 1 and 2, the polyamide fibers of the present invention (Examples 1 to 3) are polyamide fibers (Comparative Examples 1 to 4) that do not satisfy the production conditions of the present invention and commercially available nylon 6 fibers. Compared with the above, high strength and high toughness characteristics, that is, the strength suitable for rubber reinforcing fiber is 1
It satisfies the characteristics of 0.0 g / d or more, cutting elongation of 20% or more, and boiling water shrinkage of less than 10.0%.

The dip cord made of the polyamide fiber of the present invention, when embedded in rubber and subjected to vulcanization, has high strength and high elongation, that is, high toughness,
It is clear that the vulcanized cord has excellent thermal dimensional stability and good fatigue resistance.

Examples 4 to 6 and Comparative Examples 8 to 12: 0.01% by weight of copper acetate, 0.1% by weight of potassium iodide, 0.1% by weight of potassium bromide, and ethylene in the proportions shown in Table 3. Bisstearylamide-added nylon 6 chips with sulfuric acid relative viscosity of 3.4 were spun on an extruder spinning machine.

The discharge amount was adjusted so that the total yarn fineness was 840D. The die used had a hole diameter of 0.3 mm and a number of holes of 28, and the polymer temperature was 280 ° C. 10 for filtration
A μ-cut non-woven filter was used.

The spun yarn was placed directly under the spinneret, and the atmosphere was sealed with nitrogen gas of 5 Nl / min and passed through a heating cylinder having a length of 20 cm kept at 280 ° C., and then through a heat insulating zone having a length of 5 cm. The uniflow chimney with a length of 90 cm attached was passed through to quench. Chimney style is 20 ℃,
The condition was 30 m / min.

After that, by the oil supply device arranged in two stages,
Aqueous emulsion oil agent (first step) / non-aqueous oil agent (second step) = a or non-aqueous oil agent (first step) / non-aqueous oil agent (2
(Step) = B was given.

The above oily agent contains dioleoyl adipate as a main component, and contains an activator of POE (24) trimethylolpropane distearate and POE (20) hydrogenated castor oil trioleate. The applied amount of the first-stage oil was 0.5% by weight of oil on the yarn, and the second-stage oil was 0.5% by weight of oil on the yarn.

Next, the yarn is taken up by a take-up roll rotating at a predetermined speed, and then stretched by 5% between the first supply roll and the second supply roll heated to 40 ° C.
One-stage stretching with the first stretching roll heated to 80 ° C., and two-stage stretching with the second stretching roll heated to the temperature (final stretching temperature) shown in Table 3 at the stretching ratio shown in Table 3. Then, the film was relaxed and wound between a second stretching roll and a relaxing roll heated to 140 ° C.

For each polyamide fiber obtained by the above-mentioned method, Table 3 also shows the spinning conditions, and the evaluation results of the fiber structure parameters and fiber physical properties.

[0111]

[Table 3] As is clear from the results in Table 3, the polyamide fiber of the present invention (Examples 4 to 5) has a higher strength than the polyamide fiber (Comparative Examples 8 to 12) that does not satisfy the production conditions of the present invention. High toughness characteristics, that is, suitable for fishing net fibers, having a strength of 8 g / d or more and a cutting elongation of 25% or more,
Moreover, the boiling water shrinkage satisfies the characteristics of 10% or more.

[0112]

As described above, the high-strength polyamide fiber of the present invention satisfies the requirements of high strength and high toughness, and particularly when the strength is 10.0 g / d or more and the cutting elongation is 20% or more. In addition, by utilizing the characteristics that the shrinkage rate of boiling water is less than 10.0% and the decrease in strength during the vulcanization process is small, it is possible to reduce the amount of material used when used as a rubber reinforcing cord, It greatly contributes to cost reduction and weight reduction.

The high strength polyamide fiber of the present invention is
Especially, the strength is 8.0 g / d or more, the cutting elongation is 25% or more, the boiling water shrinkage is 10.0% or more, and the durability is excellent and the transparency is good. It is also suitable as a fiber for fishing nets.

Further, according to the method for producing a high-strength polyamide fiber of the present invention, a low-viscosity mineral oil is used as a diluent for an oil crude oil like a non-aqueous oil agent which has been conventionally used for producing a high-strength polyamide fiber. Since it does not need to be used, there is a merit that the basic unit of oil agent decreases, and because it does not use a low-viscosity mineral oil with a relatively low boiling point, it is also advantageous in disaster prevention, so polyamide fiber with high strength and high toughness can be efficiently used. Can be manufactured.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location D02G 3/48

Claims (11)

[Claims] 1. A higher alkyl amide compound is contained,
A high-strength polyamide fiber obtained by melt-spinning and stretching a polyamide composition having a sulfuric acid relative viscosity of 3.0 or more, and having the following fiber structure parameters (a) to (e): Polyamide fiber. ⊚ (a) Birefringence (Δn): Δn ≧ 55 × 10 ⁻³ (b) Differential birefringence (δΔn = Δna−Δnc): δΔn
≦ −2 × 10 ⁻³ (however, Δna: birefringence at a position of 0.95 from the center to the surface, Δnc: birefringence at the center) (c) Crystal orientation degree (fc): fc ≧ 0.88 (d) Degree of orientation of amorphous molecules (fa): fa = 0.70-0.
85 (e) Mechanical tangent loss (ta
nδ) Main dispersion peak temperature (Tα) on the curve: Tα ≦
113 ° C. 2. The high-strength polyamide fiber according to claim 1, wherein the content of the higher alkylamide compound with respect to the polyamide is in the range of 0.01 to 0.2% by weight. 3. The high-strength polyamide fiber according to claim 1, which is a multifilament having a single yarn number of 100 denier or less and a single yarn number of 20 or more. 4. A patent characterized in that the strength is 10.0 g / d or more, the cutting elongation is 20% or more, and the boiling water shrinkage ratio is less than 12.0%. Three
The high-strength polyamide fiber described in. 5. The high-strength polyamide fiber according to claim 4, which is used as a rubber-reinforcing fiber. 6. The high strength according to claim 1, 2 or 3, wherein the strength is 8.0 g / d or more, the breaking elongation is 25% or more, and the boiling water shrinkage is 10% or more. Strength polyamide fiber. 7. The high-strength polyamide fiber according to claim 6, which is used as a fiber for fishing nets. 8. The higher alkylamide compound is 0.01
In a heating cylinder at 250 ° C or higher in which a polyamide composition containing 2 to 2% by weight and a sulfuric acid relative viscosity of 3.0 or more is melt-spun at a temperature of 280 to 310 ° C, and a spun yarn is arranged immediately below the spinneret. It is slowly cooled and then rapidly solidified, and then an aqueous emulsion oil agent is applied to this cooling thread, followed by hot drawing, which is characterized by the following (a) to (e) fiber structure parameters. Method for producing high-strength polyamide fiber. ⊚ (a) Birefringence (Δn): Δn ≧ 55 × 10 ⁻³ (b) Differential birefringence (δΔn = Δna−Δnc): δΔn
≦ −2 × 10 ⁻³ (however, Δna: birefringence at a position of 0.95 from the center to the surface, Δnc: birefringence at the center) (C) Crystal orientation degree (fc): fc ≧ 0.88 (d) Degree of orientation of amorphous molecules (fa): fa = 0.70-0.
85 (e) Mechanical tangent loss (ta
nδ) Main dispersion peak temperature (Tα) on the curve: Tα ≦
113 ° C. 9. The method for producing a high-strength polyamide fiber according to claim 8, wherein the water-based emulsion oil agent contains a leveling agent and an activator as essential components. 10. The birefringence of the undrawn yarn is from 2 × 10 ⁻³ to.
The method for producing high-strength polyamide fiber according to claim 8 or 9, characterized in that it is in the range of 20 x 10 ^-3 . 11. The production of high-strength polyamide fiber according to claim 8, 9 or 10, wherein the final stretching temperature during stretching is 210 ° C. or higher and the total stretching ratio is 3.5 to 6.5. Method.