JP3281111B2 - Method for producing polyamide fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to polyamide fibers, in particular,
The present invention relates to a spinning method for polyhexamethylene adipamide fiber, poly ε-caproamide fiber and the like. More specifically, the present invention provides a method for spinning a polyamide fiber, particularly a polyhexamethylene adipamide fiber, which can be expected to have less macroscopic structural defects of the fiber, for example, less fluff, and potentially improve toughness. And polyhexamethylene adipamide fibers used for tire cords and belt cords for reinforcing rubber, for computer ribbons, and for airbag base fabrics.

[0002]

2. Description of the Related Art Polyhexamethylene adipamide (nylon 66) fibers have excellent strength, toughness, heat resistance, dyeing properties, coloring properties, etc., and are widely used as fibers for industrial materials, interior bedding, and clothing. It is used. In particular, because of its excellent strength, toughness, heat resistance, adhesiveness to rubber, and the like, it is widely used as a fiber for a tire cord or a fiber for an air bag. In any case, the quality of the processing characteristics at the weaving and knitting stages depends on the macro uniformity of the fiber structure at the yarn stage. In addition, the quality of the fiber structure following the physical processing and physicochemical processing that the original yarn undergoes before reaching the final product also affects the durability of the final product. In this regard, what is required at the yarn stage is an absolute increase in the uniform amorphous fraction of the packing density of the molecular chains.

When the fiber structure has poor macro uniformity, it often appears as fluff. This is because the polymer melt coming out of the spinner is cooled, taken up by a take-up roll, and subjected to a stretching operation between the next rolls, whereby microfibrils or microfibrils present in the statistically structurally distorted portion of the fiber are obtained. Cutting is considered to be a fundamental cause. Here, the structurally distorted portion is specifically a so-called spherulite portion, and the only way to reduce this is to increase the supercooling temperature. In order to increase the supercooling temperature, in the related art, the temperature of the discharged polymer melt is increased, the temperature of the cool air to be applied to the polymer melt is reduced, the speed of the cool air is increased, and the applied cool air is uniformly applied from the circumferential direction. In the case where cold air is applied from one direction, it has been coped with by optimizing the spinning arrangement from which the polymer melt is discharged and by lowering the single yarn denier. In these methods, the fraction of molecular chains contained in the amorphous portion necessarily increases due to the reduction in spherulites. However, when the so-called cold drawing method is used, the take-up roll temperature currently used industrially is set to the glass transition point of the polymer (around 65 ° C. for polyamide). At present, it is far from achieving a uniform aggregation structure by uniformly stretching the molecular chains to be formed. In particular, when the polymer melt temperature is raised, the problem of polymer decomposition is accompanied.

[0004] On the other hand, various methods have been proposed for realizing an absolute increase in the uniform amorphous fraction of the packing density of the molecular chains, referred to as increasing the toughness of polyamide fibers. Techniques proposed other than those described above, 1) increasing the degree of polymerization of the polymer (Japanese Patent Laid-Open No. 4-153331), and 2) zone (non-contact type) stretching at a high temperature, as judged by patents and academic papers (Japanese Unexamined Patent Publication (Kokai) No. 61-194209), 3) After the spinning speed is reduced, multi-stage drawing is performed.
4) Use of a non-aqueous oil agent (Japanese Patent Application Laid-Open No. 63-91235). 5) Actively steaming of the discharged and solidified yarn at about 140 ° C. promotes crystallization. However, the method 5) is inconsistent with the improvement of durability and fatigue resistance after the raw yarn becomes a final product. 2) Although it depends on the degree of stretching, it realizes an absolute increase in the uniform amorphous fraction of the packing density of the molecular chains, and furthermore, since the yarn does not come into contact with a medium such as a roll, a macro structural defect ( Fuzz) is also difficult to produce, but it is extremely disadvantageous in terms of productivity, manufacturing equipment, and cost. In the case of 3), not only is it disadvantageous in terms of equipment and productivity, but also the chance of contact with a medium such as a roll increases,
Structural defects due to friction are also likely to occur. 4) has a problem in terms of working environment and proportional manufacturing cost.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a macro-uniformity of the fiber structure at the yarn stage, specifically, a physical treatment which is less fuzzy and is applied to a final product.
Providing technology to produce yarns with good fiber structure compliance with physicochemical treatment, improving processing characteristics in processing stages such as weaving, knitting, and adhesive treatment, and improving durability of final products Is to do.

[0006]

Means for Solving the Problems The present inventors have studied the mechanism of the occurrence of microstructural defects during the spinning process of polyamide-based fibers, particularly polyhexamethylene adipamide fibers, from the viewpoint of fiber structure theory. As shown in FIG. 1, it was found that the fuzz generation rate showed the maximum in the specific amorphous content region of the spun fiber (in FIG. 1, the amorphous content of the final drawn yarn was expressed by tan δ defined by storage elastic modulus and loss elastic modulus). And the maximum value of tan δ is represented by tan δ max). As a result of earnestly studying a spinning technique that has escaped that area and has the potential of increasing toughness, the present invention has been reached.

That is, according to the present invention, the polyamide is melt-spun, cooled, taken up by a take-up roll, and then stretched between godet rolls.
A take-up roll having a surface temperature gradient in the length direction is used, and the surface temperature Ti [° C.] of the region where the take-up yarn is introduced in the take-up roll and the surface area where the take-up yarn is transferred to the next godet roll Is set within a range that satisfies the following formulas (1) and (2), respectively.

Tgc−10 ° C. ≦ Ti ≦ Tgc + 40 ° C., (1) Tg ≦ Tt ≦ Tmax + 15 ° C. (2) (However, in the formula (1), Tgc [° C.] indicates that the storage modulus of the take-up yarn is in the glass transition region. Complete the sharp drop at the temperature,
In the formula (2), Tg [° C.] is the glass transition temperature of the polyamide determined by a scanning differential calorimeter, and Tmax [° C.]
Indicates the temperature at which a peak of tan δ defined by the ratio of the loss elastic modulus to the storage elastic modulus of the take-off yarn is given. The production method of the present invention is basically applicable to spinning of various polyamide fibers. Examples of the polyamide-forming unit include aliphatic dicarboxylic acids such as sebacic acid and dodecanoic acid, terephthalic acid, aromatic dicarboxylic acids such as isophthalic acid and aliphatic diamines such as hexamethylenediamine, and aromatic diamines such as meta-xylylenediamine. Ring-opening polymers of various polycondensates, ω-aminocarboxylic acids such as ε-aminocaproic acid, and lactams such as caprolactam and lauryl lactam. Particularly preferably, it is applied to polyhexamethylene adipamide.

Further, the above-mentioned polyamides are usually added with additives such as inorganic phosphorus compounds such as phosphoric acid and sodium hypophosphite, organic phosphorus compounds such as phenylphosphonic acid and triphenylphosphite, and phosphorus-nitrogen. Complex salts,
Polymerization catalysts such as phosphorus-nitrogen compounds, copper compounds such as copper acetate, copper bromide, copper iodide, copper complex salts of 2-mercaptobenzimidazole, 2-mercaptobenzimidazole, tetrakis- [methylene-3- (3,5 -Di-tert-butyl-4-
(Hydroxyphenyl) -propionate] -Methane and the like, light stabilizers such as manganese lactate and manganese hypophosphite, matting agents such as titanium dioxide and kaolin, ethylene bisstearylamide, partially methylolated products, stearic acid A lubricant such as calcium, a plasticizer, and a crystal inhibitor can be contained.

The production method of the present invention is basically the same as disclosed in
Conventional melt spinning equipment such as that disclosed in JP-A-199812 can be used. The features of the present invention are as follows.
In the temperature profile of the surface of the take-up roll of the stage and the absolute temperature set value of the surface. That is, using a first-stage take-off roll having a surface temperature gradient in the length direction, the glass transition temperature of the polyamide to be used is Tg, and the temperature at which the storage elastic modulus of the take-off yarn rapidly decreases in the glass transition region is completed. To Tg
c, tan δ defined by the ratio of loss modulus to storage modulus
And the surface temperature Ti in the region where the take-up yarn is introduced is Tgc−10 ° C.
Ti ≦ Tgc + 40 ° C., the temperature Tt of the surface region where the take-up yarn is transferred to the second godet roll is Tg ≦ Tt ≦ T
It is characterized in that it is set in a range satisfying max + 15 ° C. Preferably, the first two laps are threaded on the Ti portion, and the Tt portion thereafter is preferably used. here,
FIGS. 2 and 3 show the definition of the temperature indicated by the symbol. FIG. 2 shows the relationship between the amount of heat absorbed and generated by the polymer and the temperature. Figure 3 shows the fiber t
An an δ-T (temperature) curve and an E′-T curve are shown.
FIG. 2 shows Tg, and FIG. 3 shows Tgc and Tmax. The measurement conditions employed for determining each temperature in this definition are shown below: Tg: scanning differential calorimeter (manufactured by Seiko Electronics Co., Ltd .: DSC2)
00), about 8 mg of a sample (1 godet roll (surface temperature: 65 ° C .; take-up yarn)) was sealed in an aluminum pan, and the temperature was raised at a rate of 20 ° C. /
Tgc, Tmax: Viscoelasticity measuring device (Orientec: Leo Vibron DDH type), sample (same as above), heating rate, 5 ° C./min, measuring frequency; 110 Hz As a method of attaching, there is a method of disposing materials having different thermal conductivity in the length direction inside the roll.

The surface temperature Ti in the region where the take-up yarn is introduced
The reason why is (Tgc-10) ° C. or higher is that the molecular chain in the amorphous region is thermally easily movable, and the structural distortion of the solidified yarn discharged from the spinneret is eliminated, and at the same time, (Tgc-1) in order to incorporate the molecular chain existing at the crystal region interface due to the active molecular chain motion into the amorphous portion.
0) ° C or lower, this effect is not exerted. On the other hand, when Ti exceeds (Tgc + 40) ° C, the mobility of the molecular chain is guaranteed, but the tan δ of the yarn is lowered because it enters the crystallization temperature range. And the next stretchability decreases, T
i is preferably as close to Tgc as possible. Further, if the temperature Tt of the surface region where the take-up yarn is transferred to the next godet roll (second godet roll) is set to be the same as Ti, the stretched yarn sags or rolls on the roll, It is not preferable in terms of spinning stability, and needs to be set to a lower temperature side than Ti. If the temperature is less than Tg, the temperature difference between Ti and Tt is too large, so that the material shrinks sharply and Ti
In this case, the structural strain that has been eliminated in step (2) partially recurs, which should be avoided, and the stretchability between two godet rolls basically decreases. If it is larger than (Tmax + 15) ° C., the above-described slack and roll on the stretch of the stretched yarn is difficult to eliminate, which is a problem in terms of spinning stability. Taking these spinning stability, elimination of structural strain, and subsequent stretchability into consideration, T
t is preferably around Tmax. Basically, the polyamide fiber obtained by the present production method is assured of high quality,
Derived from macro fiber heterogeneity. The economic effect derived from the reduction in the number of machine stops in the post-processing step is also large.In addition, in the method of the present invention, the take-up roll is in a state in which the molecular chains present in the completely amorphous region undergo micro-Brownian motion. , Is stretched between two godet rolls and stretched while incorporating the crystal part present at the amorphous interface into the amorphous part, so that the tan δ value is kept high during the hot stretch orientation crystallization between the two godet rolls and the three godet rolls. While exhibiting mechanical strength. If the amorphous content of the drawn yarn obtained by the present method is expressed by tan δ defined by the ratio of the storage elastic modulus to the loss elastic modulus, 1.2 times that of the drawn yarn obtained by the conventional cold drawing method is guaranteed. You. This is
Improves the toughness of polyamide fibers by eliminating macroscopic structural non-uniformity of spun fibers in the hot drawing process at the yarn production stage, and realizing the ability to respond to external physicochemical forces in the post-processing process It also leads to improved fatigue resistance. Therefore,
This spinning method can be applied to spinning of high dimensional stability, high fatigue resistance fiber materials used for tire cords and the like and computer ribbons, and fiber materials for inners, carpets and clothing.

In the present invention, other spinning conditions are specifically determined individually according to the use of the fiber to be obtained, but are not particularly limited.
m / min or more, and the stretching ratio is preferably 4.8 or more.
Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited thereto.

[0013]

EXAMPLE A polyhexamethylene adipamide polymer having a relative viscosity of 90% of formic acid (hereinafter referred to as VR) of 80 was polymerized by a conventional polymerization method, and then the spinning speed was measured using an apparatus shown in FIG. The fiber was spun and stretched at 2000 m / min to obtain a polyhexamethylene adipamide fiber. The glass transition temperature Tg of the first stage the polymers of take-up rolls at that time, the cited up yarn storage modulus completes abruptly decreased in the glass transition region temperature T
gc , tan defined by the ratio of loss modulus to storage modulus
Table 1 shows the temperature Tmax at which the peak of δ is given. Table 2 shows spinning conditions, fiber physical properties, and the number of fluffs when the surface temperature Ti in the region where the take-off yarn is introduced and the surface region temperature Tt in which the take-off yarn is transferred to the second godet roll are arbitrarily changed. Show.

The physical properties of the fibers used herein are determined by using an Autograph S-100C manufactured by Shimadzu Corporation with a descent speed of 30 cm / cm for a 25 cm yarn sample to which 80 turns / m twist has been applied.
And a value measured at a chart speed of 60 cm / min. The number of fluffs referred to herein is a value measured at a spinning speed of 500 m / min for 20 minutes using a fluff detector; Toray Fly Counter TD-106.

The first-stage take-up roll temperature Tt is 65 ° C.
80 ° C, 90 ° C, 135 ° C, Ti at 70 ° C, 85 ° C, 9
When the temperature is changed to 5 ° C. or 140 ° C., when Tt is 135 ° C., the temperature approaches the crystallization temperature range, and the tan δ of the yarn decreases, the next stretchability decreases, and the number of fluffs increases. In this implementation, 1
By setting the stage take-up roll temperature Tt to 90 ° C. and Ti to 95 ° C., it is possible to increase tan δ and to obtain fibers with less fluff without changing the fiber properties.

Next, a fatigue resistance test of the obtained yarn was performed. Each of the raw yarns was twisted 32 times / 10 cm, and then each of the two twists was twisted 32 times / 10 cm to obtain a raw cord. The raw cord was treated with a resorcinol-formaldehyde-latex liquid using a three-oven hot stretch apparatus under the following conditions. This treated cord was vulcanized under vulcanization conditions of 155 ° C. × 40 minutes, and a fatigue resistance test was performed according to a Goodyear tube fatigue test. The good-ear tube fatigue test mentioned here is as follows.

Method according to JISL-101733.2.2.1A Tube shape Inner diameter 12.5mm Outer diameter 26mm Length 230mm Bending angle 90 ° Internal pressure 3.5kgf / cm ² Number of rotations 850rpm Table 2 Good ear method tube fatigue test The results are shown.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

EFFECT OF THE INVENTION The polyamide fiber of the present invention has low fluff and has a fiber structure with high tan δ, thereby improving toughness, and is used for tire cords and belt cords for rubber reinforcement, for computer ribbons, and for airbag base fabrics. When used for, for example, it is a product with excellent durability.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the fluff generation rate of a polyhexamethylene adipamide fiber and a tan δmax value.

FIG. 2 is a graph showing the relationship between the heat absorption and heat generation of a drawn yarn and the temperature, measured using a scanning differential calorimeter (DSC 200).

FIG. 3 is a graph showing the relationship between storage elastic modulus (E ′), tan δ, and temperature of a drawn yarn.

FIG. 4 is a diagram illustrating an example of a spinning machine and a stretching machine used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spin head 2 Spinneret 3 Heating cylinder 4 Filament 5 Cooling air chamber 6 Oiling roll 7 Pretension roll, 8 Take-up roll (1st godet roll) 9 2nd godet roll 10 3rd godet roll 11 Winding machine

Claims (1)

(57) [Claims] When a polyamide is melt-spun, cooled, taken up by a take-up roll and stretched between godet rolls, a take-up roll having a surface temperature gradient in a longitudinal direction is used as the take-up roll. Used and in the take-up roll, the surface temperature Ti in the region where the take-up yarn is introduced
[° C.] and the temperature Tt [° C.] of the surface area where the take-up yarn is transferred to the next godet roll, respectively (1),
(2) A method for producing a polyamide fiber, characterized by setting the value in a range satisfying the expression (2). Tgc-10 ≦ Ti ≦ Tgc + 40 (1) Tg ≦ Tt ≦ Tmax + 15 (2) (However, in the formula (1), Tgc [° C.] indicates that the storage elastic modulus of the take-off yarn rapidly decreases in the glass transition region. Temperature,
In the formula (2), Tg [° C.] is the glass transition temperature of the polyamide determined by a scanning differential calorimeter, and Tmax [° C.]
Indicates the temperature at which the peak of tan δ defined by the ratio of the storage modulus to the loss modulus of the take-off yarn is given. )