JPH06330405A - Production of polyamide fiber - Google Patents

Abstract

PURPOSE:To obtain a polyamide fiber having a little fluffs, a high amorphous content and excellent durability and being suitable for the use as various industrial materials such as rubber-reinforcing tire cord, belt cord, computer ribbon and base cloth for air bag. CONSTITUTION:A polyamide fiber is produced by the melt-spinning of a polyamide using a yarn take-up godet roll having mirror-polished take-up surface and matte-finished delivery surface region and a 1st-stage take-up roll satisfying the formula Tgc-10<=Ts<=Tgc+40 deg.C wherein Tgc is the temperature to complete the abrupt lowering of the storage elastic modulus of the taken-up yarn in the glass transition range and Ts is the surface temperature of the take-up roll.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for spinning polyamide fibers such as polyhexamethylene adipamide fibers and poly ε-caproamide fibers. More specifically, it provides a method for spinning a polyamide fiber having a macroscopic structural defect of a fiber, for example, a small number of fluffs, and potentially improving toughness, and a tire cord for rubber reinforcement,
The present invention relates to a polyamide fiber, particularly a polyhexamethylene adipamide fiber, which is used for belt cords, computer ribbon applications, air bag fabric applications, clothing applications and the like.

[0002]

2. Description of the Related Art Polyhexamethylene adipamide (nylon 66) fiber is widely used as a fiber for industrial materials, interior bedding, and clothing because of its excellent strength, toughness, heat resistance, dyeability, and color development. It is used. In particular, since it has excellent strength, toughness, heat resistance, and adhesiveness with rubber, it is widely used as a fiber for tire cords and a fiber for air bags. In any case, the quality of the processing characteristics at the weaving and knitting stage depends on the macroscopic uniformity of the fiber structure at the raw yarn stage. In addition, whether or not the fiber structural followability with respect to the physical treatment and the physical chemical treatment that the raw yarn receives until reaching the final product also affects the durability of the final product. In this respect, what is required in the raw yarn stage is an absolute increase in the uniform amorphous fraction of the packing density of the molecular chains.

When the macroscopic uniformity of the fiber structure is poor, it often appears as fluff. This is because the polymer melt emerging from the spinneret is cooled, wound on a take-up roll, and stretched between subsequent rolls to produce microfibrils or microfibrils present in the statistically structurally distorted part of the fiber. It is considered that the bundle is cut off basically. Here, the structurally strained portion is specifically a so-called spherulite portion, and in order to reduce it, the supercooling temperature must be increased. In order to increase the supercooling temperature, in the conventional technique, the temperature of the discharged polymer melt is raised, the temperature of cold air given to the polymer melt is lowered, the velocity of cold air is increased, and the given cold air is uniformly given from the circumferential direction. In the case where cold air is applied from one direction, optimization has been made on the arrangement of spinnerets from which the polymer melt is discharged, and the single yarn denier has been lowered. In these methods, the fraction of molecular chains accommodated in the amorphous portion is necessarily increased due to the decrease of spherulites. However, when the so-called cold stretching method, which sets the take-up roll temperature currently used industrially at the glass transition point of the polymer (near 65 ° C. for polyamide), is present in the amorphous region only by these methods. The present situation is that it is far from obtaining a uniform aggregated structure by uniformly stretching the resulting molecular chain. In particular, raising the polymer melt temperature is accompanied by problems of polymer degradation.

On the other hand, various methods have been proposed as a method for realizing an absolute increase in the uniform density of the packing density of the molecular chains, which is referred to as increasing the toughness of the polyamide fiber. Judging from patents and academic papers, the technologies proposed other than the ones mentioned above 1) increase the polymerization degree of the polymer (JP-A-4-153331), 2) draw at high temperature in a zone (non-contact type) (Japanese Patent Laid-Open No. 61-194209), 3) slowing down the spinning speed, and then performing multistage drawing,
4) Use of a non-aqueous oil agent (Japanese Patent Laid-Open No. 63-91235), 5) Discharge, cooling, and solidification of the yarn actively steaming at about 140 ° C. to promote crystallization. However, the method 5) contradicts the improvement of durability and fatigue resistance after the raw yarn is made into a final product. Although 2) depends on the degree of drawing, it realizes an absolute increase in the uniform density of the packing density of molecular chains, and since the thread does not come into contact with a medium such as a roll, macroscopic structural defects ( It is difficult to produce fluff, but it is extremely disadvantageous in terms of productivity, manufacturing equipment, and cost. The method 3) is not only disadvantageous in terms of equipment and productivity, but also increases the chances of contact with media such as rolls.
Structural defects due to friction are also likely to occur. Furthermore, the method 4) has problems in terms of work environment and proportional manufacturing cost.

Further, Japanese Patent Laid-Open No. 4-245909 discloses that
In the direct spinning and drawing of synthetic fibers, the spun, cooled and lubricated yarn is taken up at 300 m / min or more, and subsequently subjected to multi-stage drawing and heat treatment using a plurality of roller groups, and then 2000 m / min. At the time of winding up as described above, at least one roller group among the above roller groups is composed of a roller having a mirror-finished surface with a roughness of 1 s or less and a roller having a satin-finished surface with a roughness of 4 s to 8 s. Disclosed is a direct spinning / drawing method for synthetic fibers, which comprises applying a yarn to the mirror-finished roller, followed by stretching the product to a satin-finished roller and subjecting it to heat treatment. However, this is a manufacturing patent based on the idea of slowing the strain rate in stretching, and there is no description that considers the effect of temperature in the strain process on the fiber structure.

[0006] In these conventional techniques, there is almost no proposal of a methodology from the temperature condition of the take-up roll and the fiber structure theory.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a macroscopic homogeneity of the fiber structure at the stage of the raw yarn, specifically, a small number of fluffs, and a physical treatment to reach the final product,
Providing technology for manufacturing raw yarns with good fiber structural followability to physical and chemical treatments, improving processing characteristics at processing stages such as weaving, knitting, and adhesive treatment, and also improving durability of final products To do.

[0008]

Means for Solving the Problems The present inventors have studied the mechanism of microstructural defect generation in the spinning process of polyamide fibers, especially polyhexamethylene adipamide fiber, from the viewpoint of fiber structure theory. It was found that the fluff generation rate showed the maximum in the specific amorphous content region of the spun fiber as shown in Fig. 1 (in Fig. 1, the amorphous content of the final drawn yarn was expressed by tan δ defined by the storage elastic modulus and the loss elastic modulus. The maximum value of tan δ is expressed as a tan δmax value). Then, as a result of earnestly studying a spinning technique that has the potential to increase the toughness while leaving that region, the present invention has been achieved.

That is, the present invention melt-spun polyamide,
After being cooled and taken up by the take-up roll, when the stretching is performed between the godet rolls, the surface temperature T of the take-up roll is
A method for producing a polyamide fiber, wherein s [° C.] satisfies the following general formula, and in the take-up roll, the surface region where the yarn is handed over to the next godet roll is satin finished.

Tgc-10≤Ts≤Tgc + 40 (where Tgc [° C] is the temperature at which the storage elastic modulus of the yarn drawn by the take-up roll shows a sharp drop in the glass transition region). . In the melt-spinning of a polyamide polymer, the production method of the present invention is different from the conventional cold stretching near the glass transition temperature (Tg) in a state where the molecular chains completely present in the amorphous region cause micro Brownian motion. A draw roll (1 godet roll) is stretched between 2 godet rolls, and the crystal part existing at the amorphous interface is drawn into the amorphous part and stretched.
During hot stretch orientation crystallization between godet rolls, tan
The present invention relates to a method of developing mechanical strength while maintaining a high δ value.

The production method of the present invention is basically applicable to various production methods of polyamide fibers. As the polyamide forming unit, an aliphatic dicarboxylic acid such as sebacic acid or dodecanoic acid,
Terephthalic acid, various polycondensates of aromatic dicarboxylic acids such as isophthalic acid and aliphatic diamines such as hexamethylenediamine, aromatic diamines such as metaxylylenediamine, ω-aminocarboxylic acids such as ε-aminocaproic acid, Examples thereof include ring-opening polymers of lactams such as caprolactam and lauryllactam. Particularly preferably, it is applied to polyhexamethylene adipamide.

Further, for the above-mentioned polyamide, there are usually used additives such as inorganic phosphorus compounds such as phosphoric acid and sodium hypophosphite, organic phosphorus compounds such as phenylphosphonic acid and triphenylphosphite, phosphorus-nitrogen. Complex salt,
Polymerization catalysts such as phosphorus-nitrogen compounds, copper acetate, copper bromide, copper iodide, copper compounds such as 2-mercaptobenzimidazole copper complex salt, 2-mercaptobenzimidazole, tetrakis- [methylene-3- (3,5 -Di-t-butyl-4-
(Hydroxyphenyl) -propionate] -Heat stabilizers such as methane, light stabilizers such as manganese lactate and manganese hypophosphite, delusterants such as titanium dioxide and kaolin, ethylenebisstearylamide, methylol derivatives thereof, stearic acid A lubricant such as calcium, a plasticizer, and a crystallization inhibitor can be included.

The manufacturing method of the present invention is basically disclosed in JP-A-59-59.
It can be used by using a usual melt spinning equipment such as 199812. The feature of the present invention is that the temperature at which the storage elastic modulus of the yarn taken up by the take-up roll in the first stage is rapidly lowered in the glass transition region is Tgc (see FIG. 2).
And the take-up roll surface temperature Ts is Tgc-10 ≦
It is characterized in that Ts ≦ Tgc + 40 is satisfied, and the roll surface to be transferred to the next roll is so-called satin finish.

FIG. 2 shows Tgc. T used in the present invention
The measurement conditions adopted in determining gc are shown below. Tgc: Viscoelasticity measuring device (manufactured by Orientec Co .: Rhovibron DDH type), sample (1 godet roll take-up yarn) temperature rising rate, 5 ° C./min, measurement frequency; 110 Hz Surface temperature of take-up roll around which take-up yarn is wound Ts is Tg
The reason why the temperature is not lower than -10 ° C is that the molecular chains in the amorphous region are easily moved thermally, and the structural strain of the solidified filament discharged from the spinneret is eliminated and at the same time, this active molecule is eliminated. This is because the molecular chain existing at the interface of the crystal region due to chain movement is incorporated into the amorphous portion, and this effect is not exhibited at a temperature lower than Tgc-10 ° C. On the other hand, when Ts exceeds Tgc + 40 ° C., the mobility of the molecular chain is guaranteed, but since it enters the crystallization temperature region, the tan δ of the yarn is rather lowered, and the stretchability in the next step is deteriorated. , Ts are preferably as close as possible to Tgc.

Further, in the present invention, when the surface of the take-up roll is so-called mirror-finished, the stretched yarn may sag or roll on the roll, which is not preferable from the viewpoint of spinning stability. Therefore, the roll surface in the area to be delivered to the next roll must be satin finished.
Preferably, mirror finishing is performed up to the first two laps of the first stage take-up roll, and satin finishing is desirable thereafter. The elimination of the above-mentioned drawbacks due to the satin finish is interpreted as the shrinkage of the yarn due to the relative contact area between the yarn and the roll surface or the contact time slightly decreasing in the satin finish. . When the amorphous content of the final drawn yarn obtained by this method is expressed by tan δ defined by the storage elastic modulus and the loss elastic modulus, it is 1, 2 of that of the drawn yarn obtained by the conventional cold drawing method at the same strength level. Guaranteed more than twice. This leads to a reduction in the statistical defects of the fibers in the drawing operation, for example a reduction in fluff. Further, it is the reason that the improvement of the followability to the physical and chemical external force and the improvement of the fatigue resistance, which are received in the post-processing stage, are realized, as compared with the polyamide fiber obtained by the conventional method.

Further, in the present invention, other spinning conditions are individually determined by the use of the fiber to be obtained and are not particularly limited, but the spinning speed is 150 from the viewpoint of strength and the like.
It is preferable that the stretching ratio is 0 m / min or more and the stretching ratio is 4.8 or more. Examples will be described below, but the invention is not limited thereto.

[0017]

EXAMPLE After polyhexamethylene adipamide having 90% relative viscosity of formic acid (hereinafter referred to as VR) of 80 was polymerized by a conventional polymerization method, a spinning speed of 200 was obtained by using the apparatus shown in FIG.
The polyhexamethylene adipamide fiber was obtained by spinning and drawing at 0 m / min. Table 1 shows the temperature Ts of the first-stage take-up roll at that time and the temperature Tgc at which the storage elastic modulus of the take-up yarn completes a sharp decrease in the glass transition region. The spinning conditions, fiber properties, and number of fluffs used here are shown in Table 2, and the first-stage roll used is shown in FIG.

The fiber physical properties referred to herein are 30 cm / descent rate with respect to a sample of 25 cm raw yarn to which 80 times / m of twist is added by using Autograph S-100C manufactured by Shimadzu Corporation.
Minutes, the value measured at a chart speed of 60 cm / min. Further, the number of fluffs here is a value measured by using a fluff detector; Toray Fly Counter TD-106 at a spinning speed of 500 m / min for 20 minutes.

The fiber properties are changed by setting the temperature of the first-stage take-up roll at 100 ° C., mirror-finishing the surface roughness of the first-stage roll up to the first two laps, and matte-finishing after that. Without increasing tan δ, a fiber with less fluff can be obtained. Next, a fatigue resistance test was performed on the obtained yarn. A raw cord was produced by subjecting each of the original yarns to a twist of 32 twists / 10 cm, and then subjecting each of the two twists to a twist of 32 twists / 10 cm. This raw cord was treated with a resorcin-formaldehyde-latex liquid under the following conditions using a 3-oven hot stretcher.

[0020] This treated cord was vulcanized under vulcanization conditions of 155 ° C. × 40 minutes, and a fatigue resistance test was conducted according to the Goodyear tube fatigue test. The Goodyear tube fatigue test here is as follows.

Method conforming to JISL-10173.2.2.1A Tube shape Inner diameter 12.5 mm Outer diameter 26 mm Length 230 mm Bending angle 90 degrees Internal pressure 3.5 kgf / cm ² Rotation speed 850 rpm Table 2 shows Goodyear tube fatigue test. The results are shown.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

EFFECT OF THE INVENTION The polyamide fiber of the present invention has less fiber and has a fiber structure with a high tan δ, so that the toughness is improved, and tire cords for rubber reinforcement, belt cords, computer ribbons, air bag base fabrics, etc. When used for other purposes, it becomes a product with excellent durability.

[Brief description of drawings]

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

FIG. 2 is a graph showing the relationship between the storage elastic modulus (E ′) and the tan δ value of the yarn drawn by the take-up roll of the first stage and the temperature T.

FIG. 3 is a diagram showing an example of a spinning machine and a stretching machine used in the present invention.

FIG. 4 is a diagram showing an example of a first stage take-up roll according to the present invention.

[Explanation of symbols]

 1 Spin Head 2 Spinneret 3 Heating Cylinder 4 Filament 5 Cooling Air Chamber 6 Oiling Roll 7 Pre-tension Roll, 8 Take-up Roll (1st Godet Roll) 9 2nd Godet Roll 10 3rd Godet Roll 11 Winder

Claims (1)

[Claims] 1. When the polyamide is melt-spun, cooled, taken up by a take-up roll, and stretched between godet rolls, the surface temperature Ts [° C.] of the take-up roll satisfies the following general formula: Further, in the take-up roll, the surface area where the yarn is delivered to the next godet roll is satin-finished, which is a method for producing a polyamide fiber. Tgc−10 ≦ Ts ≦ Tgc + 40 (where Tgc [° C.] represents the temperature at which the storage elastic modulus of the yarn drawn by the take-up roll completes a sharp decrease in the glass transition region)