JPH06240513A - Production of polyamide fiber - Google Patents

Abstract

PURPOSE:To produce a polyamide fiber excellent in fatigue resistance and abrasion resistance and exhibiting a high toughness by specifying the water content of a polyamide melt or its chip when melt spinning it and applying a non-aqueous finishing agent when discharging it. CONSTITUTION:The water content of melt or chip of a polyamide such as polyhexamethylene adipamide is controlled to >= the amount accommodatable in a saturated steam atmosphere in a melt temperature range and <= the amount accommodatable in a saturated steam atmosphere in a cooling solidification temperature range of the discharged polyamide melt and melt spinning thereof is carried out. A non-aqueous finishing agent is applied to the discharged yarn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide in which a raw material polymer is prepared on the basis of a polycondensation reaction, such as polyhexamethylene adipamide fiber or a poly ε-caproamide fiber whose raw material polymer is prepared on the basis of ring-opening polymerization. The present invention relates to a spinning method characterized by adjusting the amount of water in a polymer melt to a higher value than before in the production of the above, and adding a non-aqueous finishing agent during spinning. More specifically, it is highly dimensional-stable and fatigue-resistant fiber materials used for rubber cords such as tire cords, belt cords and computer ribbons, and fiber materials for inners, carpets and clothing, depending on the dyeability and the case. In particular, it relates to a method for producing a polyamide fiber that requires high toughness.

[0002]

2. Description of the Related Art Polyamide fibers are used for strength, toughness,
Because of its excellent heat resistance, dyeability, and color development, it is widely used as a fiber for industrial materials, interior bedding, and clothing. Generally, a polyamide fiber, particularly a polyhexamethylene adipamide fiber has a high equilibrium coefficient when preparing a raw material polymer thereof, and is characterized by being easily polymerized as compared with polyethylene terephthalate. Also, poly ε-caproamide easily polymerizes with water as a catalyst. On the other hand, however, it has been believed that it is more appropriate to reduce the water content in the spin melt as much as possible, because the presence of water easily causes hydrolysis and side reactions. This is also a reasonable idea in that it is easy to solubilize the water present in the melt system. If insoluble water is present, the surrounding polymer undergoes so-called microphase separation, and it is considered that the water content in the melt should be as low as possible, even if estimated from the point of becoming nuclei of spherulites. In a sense, it seems natural.

Therefore, in general, the maximum water content in polymer chips and polymer melts is 1200 ppm, which is about 500.
Around ppm is adopted. However, in the case of chips and polymer melts having such water content conditions, the polymer temperature during spinning is extremely high. For example,
At least 285 in polyhexamethylene adipamide fiber
In general, a heating cylinder at a temperature higher than the polymer melting temperature is installed just below the spinneret discharge temperature, which deteriorates the working environment and at the same time causes oligomers generated due to the high temperature. At present, there are drawbacks such as the necessity of an operation for removal and a short wiping cycle of the spinneret for stable spinning. Furthermore, for polymers with high hygroscopicity such as polyamide chips, it is quite difficult to control the water content to a low level over the entire transportation route to the spinning device, and it is very energy and facility-intensive. High cost. Further, when the water content is controlled at a low water content, the water content variation directly affects the spinning stability. Further, a polymer having a higher degree of polymerization than before has a drawback that, when the water content of the chips is low, the viscosity is too high, and for example, it cannot be spun by an ordinary extruder.

On the other hand, it is a well-known fact that the so-called steam treatment (conditioning) is important for spinning stability in the process of spinning polyamide fibers, and that the structure of the polyamide raw yarn is significantly changed by moisture. In a sense, water is an important factor that determines the yarn properties. Nevertheless, the presence of water in the molten state of polymers is only vaguely debated, "less is better" simply from the point of view of decomposition based on equilibrium reactions. In fact, most patent publications and examples of patent publications do not limit or describe the water content. Even a few disclosed descriptions are generally in the range of 500 to 700 ppm, and there is no one that teaches the role or action of this water scientifically and in principle.

On the other hand, increasing the toughness of polyamide fibers not only for industrial materials but also for clothing and interior bedding is one of the fields requiring important technical improvement. Judging from patents and academic papers, the technologies proposed in this field are 1) increase the degree of polymerization of the polymer, 2) stretch in a zone (non-contact type) at high temperature, 3) increase the polymer temperature to a higher temperature, 4 ) Designing the spinneret arrangement to improve the efficiency of cooling, thinning the single yarn, 5) slowing down the spinning speed and then drawing in multiple stages, 6) using a non-aqueous oil agent, 7) discharging For example, the cooled and solidified yarn is actively steamed at about 140 ° C. to promote crystallization. Only 6) and 7) are related to water, which is also the action after the melt is discharged and solidified.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to fatigue resistance,
It is an object of the present invention to provide a method for spinning polyamide fibers having excellent wear resistance and high toughness, particularly polyhexamethylene adipamide fibers.

[0007]

Means for Solving the Problems The present inventors have investigated the action of water in the spinning process of polyamide fibers, particularly polyhexamethylene adipamide fibers and poly ε-caproamide fibers, regarding melt flow characteristics, polymerization / depolymerization. At the same time as scientifically grasping the characteristics, etc., we conducted an intensive study through actual spinning experiments, and in the region where the water content in the molten state was higher than before,
As a result of the plasticization effect and the expression of the melting point lowering phenomenon, it was confirmed that spinning is possible even with high degree of polymerization polyamide, and in some cases, the degree of polymerization does not decrease and the take-up yarn with increased amorphous amount can be spun. Moreover, on the basis of the plasticizing effect due to the high water content and the melting point lowering phenomenon, it is possible to carry out spinning at an extremely lower melting temperature than before, and further, the toughness of the yarn obtained under such conditions is improved, and The inventors have found that the addition of a non-aqueous finishing agent during spinning significantly improves spinning stability, and further improves fatigue resistance and abrasion resistance, and completed the present invention.

That is, according to the present invention, when melt-spinning a polyamide, the amount of water in the polyamide melt or chips is equal to or more than the amount of water that can be accommodated in a saturated steam atmosphere in the melting temperature range of the polyamide, and the polyamide discharged from the spinneret. It is a method for producing a polyamide fiber, which is characterized in that it is adjusted in advance to an amount of water content that can be accommodated under water vapor in a temperature range where the melt is cooled and solidified, and a non-aqueous finishing agent is added during spinning.

The spinning method of the present invention can basically be applied to spinning various polyamide fibers. As the polyamide forming unit, sebacic acid, an aliphatic dicarboxylic acid such as dodecanoic acid, an aromatic dicarboxylic acid such as terephthalic acid or isophthalic acid, an aliphatic diamine such as hexamethylenediamine, an aromatic diamine such as metaxylylenediamine, and the like Various polycondensates,
Ring-opening polymers of ω-aminocarboxylic acids such as ε-aminocaproic acid and lactams such as caprolactam and lauryllactam. Particularly, it is preferably applied to polyhexamethylene adipamide and poly ε-caprolactam.

Further, in the above-mentioned polyamide, there are usually used additives such as inorganic phosphorus compounds such as phosphoric acid and sodium hypophosphite, phosphorus such as organic phosphorus compounds such as phenylphosphonic acid and triphenylphosphite. Polymerization catalysts such as phosphorus-nitrogen compounds such as nitrogen complex salts, copper acetate, copper bromide, copper iodide, copper compounds such as 2-mercaptobenzimidazole copper complex salts, 2-mercaptobenzimidazole,
Thermal stabilizers such as tetrakis- [methylene-3- (3,5-ti-t-butyl-4-hydroxyphenyl) -propionate] -methane; light stabilizers such as manganese lactate and manganese hypophosphite; titanium dioxide; A matting agent such as kaolin, a lubricant such as ethylene bisstearylamide, a partial methylol derivative thereof, calcium stearate, a plasticizer, and a crystallization inhibitor may be included.

The lower limit of the amount of water in the polyamide melt or chips specified in the present invention is the amount of water that can be stored in a saturated steam atmosphere in the melting temperature range of the polyamide, which strictly differs depending on the type of polyamide used. However, it is 1400 ppm or more for polyhexamethylene adipamide and poly ε-caproamide. This value is much larger than the equilibrium water content in the polycondensation reaction of the polyamide having a polymerization degree of 50 or more obtained in the polycondensation reaction. Here, ppm display is 1
It is the number of mg of water that can be contained in kg of polymer. The upper limit of the amount of water is the amount of water that can be stored in a saturated steam atmosphere in the cooling and solidifying point temperature region of the discharged polyamide melt. Cooling and solidifying point temperature is a scanning differential calorimeter (DSC)
Once the polymer enclosed in the closed container is melted and held for a certain time (5 minutes), then at a constant speed (20 ° C / min)
Crystallization temperature when cooled by. This naturally depends on the type of polyamide used and the amount of water contained in the polymer at that time, but is in the range of 200 to 260 ° C., and in the case of polyhexamethylene adipamide, it is around 245 ° C. The water content at this time is approximately 5000 ppm. The amount of water that can be contained in a saturated vapor atmosphere in the melting temperature range is more than that in order to express the extension viscosity decrease of the polyamide melt with a sufficient plasticizing effect and to lower the cooling solidification point of the polymer. Yes, the moisture-containing polyamide melt is brought into a state as close as possible to the moisture adsorption / desorption equilibrium with the atmosphere immediately after being discharged, and the moisture adsorption / desorption phenomenon between the discharged yarn and the external atmosphere is apparently suppressed, It is for inhibiting the crystallization of the discharged yarn material. This is based on the apparent impediment to the mobility of water in the extruded polyamide melt, and on the basis of this prevents the rearrangement of the polymer molecules. As a result, the instability of the spinning, which is caused by the relative variation in the water content of the polymer, is significantly eliminated as compared with the conventional low water content. Furthermore, as in the conventional case, when a small amount of melt water is used, the discharged yarn material absorbs a relatively large amount of water with a decrease in the ambient temperature after discharge, and crystallization is promoted through the movement of this water content. There is also a concern. The solidifying point lowering effect and the crystallization inhibiting effect are effectively exhibited up to a water content of 5000 ppm, and conversely, crystallization is rapidly promoted when the water content is more than 5000 ppm. That is, regarding spinning of fibers having high toughness, the water content of 1400 to 5000 ppm is effective. The solidification temperature and heat of crystallization of the molten chips as a function of the water content of the chips are shown in FIG.

In actual spinning, there are two methods for giving the water content specified in the present invention to the polyamide melt system.
One is to manufacture polyamide chips separately,
All you have to do is adjust the moisture absorption method. In particular, in the production of polyamide chips, usually, the melt rope is extruded into a water bath and then cut, and the water content in the melt rope at this time is 2500 to 3500 ppm. It is relatively easy to control a high water content. On the other hand, in the so-called continuous weight / continuous spinning method, in which polymer polymerization and spinning are interlocked, after adjusting to a predetermined degree of polymerization by post-polymerization, it is adjusted by supplying water in the steps before the spin head. Since the amount of water in the melt system is higher than in the past, it may be necessary to apply a certain pressure or more to solubilize the water.
It is possible to cope with it by increasing / D or increasing the ejection linear velocity.

The polyamide is polyhexamethylene adipamide and the water content is from 1400 ppm to 5000 ppm.
When the relative viscosity of 90% formic acid is 80, the spinning temperature varies depending on the degree of polymerization of the polymer, and the spinning can be stably performed in the range of 270 ° C to 315 ° C. In the conventionally used polymer moisture content range of 500 ppm to 700 ppm, the spinning temperature is in the range of 300 ° C to 315 ° C.

The spinning method of the present invention is characterized in that the fiber surface is treated with a non-aqueous finishing agent during spinning. The spinning yield is improved and the fatigue resistance is greatly improved as compared with the case of treatment with the water-based finishing agent. There are two types of non-aqueous finishing agents, and there are a nit type that directly applies the crude oil itself and a diluting type that is diluted by applying it to an organic solvent such as kerosene.

The operation and effect of the present invention will be described below with reference to examples, but the present invention is not limited to these.

[0016]

EXAMPLES Prior to the description of the examples, polyamide chips,
In particular, the method for measuring the water content of polyhexamethylene adipamide chips and poly ε-caproamide chips will be described. Using an electric titration type trace moisture analyzer (Mitsubishi CA-05 type) and moisture vaporizer (VA-05 type), set vaporization temperature 208 ° C,
N2 carrier gas flow rate 300ml / min, END
SENS; 0.5 μg / sec, delay time; 5 minutes, background; sample weight about 1 g under 0.05 or less
It is the value measured for the pellets.

[0017]

Examples 1-2 and Comparative Examples 1-4 After polymerizing a polyhexamethylene adipamide polymer having 90% formic acid relative viscosity (hereinafter referred to as VR) of 80 by a conventional polymerization method, it was placed in a water bath at 20 ° C. The melt rope was extruded into pellets and pelletized using normal granulation equipment. Polymer water content at that time is 2800p
It was pm. The above pellets were treated by conventional drying and moisture absorption methods to obtain pellets containing water of 600 ppm and 1500 ppm.

The above-mentioned pellets were prepared by the method of JP-A-59-199812.
A polyhexamethylene adipamide fiber was obtained by spinning and drawing by a conventional method as disclosed in Japanese Patent Laid-Open Publication No. Table 1 shows the spinning conditions, the physical properties of the fibers, and the number of cutting threads at that time. The fiber physical properties referred to here are those of Shimadzu Autograph S-100.
It is a value measured by using C for a sample of a 25 cm raw yarn to which a twist of 80 times / m is added, at a descending speed of 30 cm / min and a chart speed of 60 cm / min. Further, the number of cutting yarns referred to here is the number of times of cutting yarns during a spinning time of 10 hours.

The composition of the round-up agent used for spinning is shown in Table 2.
Shown in. One part was a non-aqueous finishing agent applied to the fiber as crude oil. Further, 1 part was applied to the fiber as an aqueous emulsion. Polyhexamethylene adipamide fiber obtained from a polymer having a water content of 1500 ppm and 2800 ppm is
It shows higher toughness as compared with the conventional polyhexamethylene adipamide fiber obtained from a polymer having a water content of 600 ppm. Further, due to the plasticizing effect of water and the crystallization suppressing effect, it is possible to carry out spinning at a spinning temperature lower by 10 to 20 ° C. than in the conventional case, and stable spinning is possible. Further, the toughness of the polyhexamethylene adipamide fiber obtained under the conditions is high. Furthermore, in addition to setting the polymer moisture content higher than in the past, by adding a non-aqueous finishing agent, the spinning stability is further improved.

Next, a fatigue resistance test was conducted on the obtained yarn. A raw cord was prepared by subjecting each of the original yarns to a twist of 39 twists / 10 cm, and then subjecting each of the two twists to a twist of 39 twists / 10 cm. This raw cord was treated with a resorcin-formaldehyde-latex liquid under the following conditions using a 3-oven hot stretcher. This treated cord was vulcanized under vulcanization conditions of 155 ° C. for 40 minutes, and a fatigue resistance test was conducted according to the Goodyear tube fatigue test. The Goodyear tube fatigue test mentioned here is as follows.

Method conforming to JIS L-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 3 shows Goodyear tube fatigue test. The results are shown.

In addition to the higher polymer water content than in the past, the addition of a non-aqueous finishing agent greatly improves the fatigue resistance.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

The high water content / low temperature spinning method of the present invention fundamentally improves the working environment based on the heat of the melt spinning site,
The present invention provides a spinning method that realizes energy-saving spinning and that also improves the toughness of polyamide fibers, especially polyhexamethylene adipamide fibers, and is useful for rubber reinforcing tire cords, belt cords, and computer ribbons. It can be used for high dimensional stability, high fatigue resistance fiber materials used and fiber materials for inners, carpets and clothing. Furthermore, it can be applied to the spinning of ultra-high molecular weight polyamide, which has hitherto been impossible to discharge with an ordinary extruder. At the same time, when polymer chips are spun by an extruder, the process of drying the chip moisture, which is always performed, is simplified and energy is saved.

[Brief description of drawings]

FIG. 1 is a diagram showing the water content dependency of crystallization characteristics of polyhexamethylene adipamide.

Claims (1)

[Claims] 1. When melt-spinning a polyamide, the amount of water in the polyamide melt or chips is equal to or more than the amount of water that can be stored in a saturated steam atmosphere in the melting temperature range of the polyamide, A method for producing a polyamide fiber, which comprises: adjusting in advance to a moisture content that can be accommodated in a saturated steam atmosphere in a cooling and solidifying point temperature region, and adding a non-aqueous finishing agent during spinning.