JP4820557B2 - Pack for melt spinning and melt spinning method - Google Patents

Description

  The present invention relates to a polyhexamethylene adipamide spinning pack suitable for industrial materials and a polyhexamethylene adipamide melt spinning method using the same.

  Polyhexamethylene adipamide fiber has excellent heat resistance, mechanical properties, and chemical properties, and is widely used for clothing and industrial materials. In particular, since it is characterized by high toughness for industrial materials, it is suitably used for various materials, tire cords and airbags. For such applications, a high-strength polyhexamethylene adipamide fiber of, for example, 5 to 10 cN / dtex, obtained by using a high molecular weight polyhexamethylene adipamide resin and hot drawing at a high draw ratio, is used. It is common. At the same time, in order to improve heat resistance, it is sometimes performed to add a phosphorus-based stabilizer or copper halide to the resin. In such a case, there is a problem that stretched fluff is generated due to an additive present in the resin. . There are various methods for preventing fuzz, but generally a method for strengthening filtration of the resin during melt spinning is used.

However, if the filtration is strengthened, the pack pressure rises with time during melt spinning, and the replacement time of the spinning pack needs to be advanced earlier than usual, which is often not practical. In particular, during melt spinning of polyhexamethylene adipamide with a high degree of polymerization containing various additives, the pack pressure rises with time, and it is possible to loosen the filtration or use it with a lot of fluff, reduce the discharge flow rate, The only method available was to reduce the spinning speed and reduce the production.
Therefore, when producing a high-strength yarn of polyhexamethylene adipamide fiber by melt spinning, it is generally practiced to devise a filtration technique in order to suppress an increase in pack pressure during melt spinning. . In general, as a filtering material, a method using a filler such as sand, or a method using a metal filter material or a composite structure of a metal filter material and sand has been known.
In addition, a technique of simultaneously mixing a resin melt such as a static mixing element may be employed at the same time. In any case, the object is to reduce the influence of foreign substances in the molten resin by filtration and dispersion, and to suppress the generation of fluff as fibers.

  Patent Document 1 discloses a filter medium for polyamide using a metal filament having a wire diameter of 2 to 30 μm and a chromium ion concentration of 25% by weight or more. In Patent Document 1, it is disclosed that precipitation of insoluble copper compounds in molten polyamide is prevented by using a metal filter medium having a high chromium ion concentration, and foreign substances can be sufficiently captured. ing. The polyamide in the example used for melt spinning is nylon 6, not the polyhexamethylene adipamide resin as in the present invention. In polyhexamethylene adipamide resin, gelled product is remarkably easily generated as a foreign substance during melting. Therefore, the generated gel is clogged by the filter material and causes an increase in pack pressure. Arise.

Patent Document 2 discloses a spinning pack that melts and spins a polymer compound such as polyester, polyamide, and polyacryl that is obtained by cutting a metal wire into an appropriate length and sintering the obtained cut metal wire into a block shape. The filter medium used is disclosed. The resin disclosed in Examples in Patent Document 2 is nylon 6, and there is no disclosure about a technique for producing high-strength fibers without fluff while suppressing an increase in pack pressure with respect to the characteristic of polyhexamethylene adipamide that is easily gelled. It has not been.
JP-A-7-268716 Japanese Patent Publication No.43-13335

  The present invention provides a high-strength polyhexamethylene adipamide fiber for industrial materials, which has less fuzz, a small increase in pack pressure, and does not require a long-term replacement of the spinning pack. The present invention relates to a melt spinning pack capable of using a polyhexamethylene adipamide resin to which copper halide is added, and a melt spinning method for polyhexamethylene adipamide resin using the pack.

The inventor of the present invention has made the present invention as a result of diligent study to solve the problems in the previous term.
That is, the present invention is as follows.
(1) consists ing medium from metal fibers of the nonwoven fabric, the surface metal composition of the metal fiber nonwoven fabric, the measurement of an energy dispersive X-ray analyzer, nickel content 30 ~ 60 wt%, and molybdenum content A melt spinning pack for polyhexamethylene adipamide , having a content of 0 to 30 wt%, a molybdenum content of 0 to 30 wt%, and a filter medium having a pore size of 10 to 100 µm.
(2) The following steps:
A polyhexamethylene adipamide resin having a relative viscosity of formic acid of 60 to 110 and a phosphorus atom of 1 to 300 ppm was used as a pack pressure increase rate (MPa / (filter medium passing resin amount ) using the melt spinning pack described in the above (1). t / filter medium area m ² )) is melt-spun under conditions of 0.03-0.2 ,
A process for melt spinning polyhexamethylene adipamide having a tensile strength of 5 to 10 cN / dtex.
(3) The method for melt spinning polyhexamethylene adipamide according to (2), wherein a polyhexamethylene adipamide resin containing 0 to 400 ppm of titanium dioxide is used.

  The pack for melt spinning according to the present invention and the spinning method using the same have high heat resistance and high strength polyhexamethylene adipamide fibers for industrial materials with less fuzz, small increase in pack pressure during spinning, and pack replacement frequency. A few high-strength polyhexamethylene adipamide fibers can be obtained industrially.

Hereinafter, the present invention will be specifically described.
The metal fiber non-woven fabric as a filter medium used in the present invention is characterized in that the surface of the metal fiber has a nickel content of 20 to 100 wt% as measured by an energy dispersive X fiber analyzer.
When the nickel content in the present invention is less than 20 wt%, the pressure increase rate as a pack is large, and long-term spinning becomes difficult, which is not preferable. The nickel surface is related to the suppression of gel adhesion of polyhexamethylene adipamide, and suppresses gel deposition on the metal fiber. Nickel content is measured with an energy dispersive X-fiber analyzer, indicating the surface distribution of metal fibers, for example, nickel fibers or stainless steel fibers plated with nickel or metal fiber nonwoven fabrics with metal plating It is. A filter medium using metal fibers made of nickel is preferable.

  The thickness as the filter medium is preferably 0.1 to 5 mm. If it is less than 0.1 mm, the filter medium may not withstand the filtration pressure and may be damaged. If it is thicker than 5 mm, the filtration effect reaches a peak and only the initial pressure is increased unnecessarily. Although the porosity and pore size (void size) of the nonwoven fabric vary depending on the wire diameter of the metal fiber used, the wire diameter is preferably 10 to 200 μm in the present invention. It is preferable to integrate by ligation. The pore size represents a void size after sintering the metal fiber, and this pore size can be obtained by a normal bubble point method.

  The pore size of the filter medium using the metal fiber of the present invention needs to be 10 to 100 μm. Preferably it is 15-80 micrometers, More preferably, it is 20-40 micrometers. When the pore size is less than 10 μm, the pack pressure is greatly increased and the pack life is shortened. When it is larger than 100 μm, filtration is not sufficient, and the quality of the obtained yarn may be deteriorated. The configuration of the filter medium equipped in the pack of the present invention may be a known form such as a disk filter medium, candle filter medium or leaf disk filter medium that may be arranged in a single layer or multiple layers, and is not particularly limited. The leaf disk filter medium is advantageous from the viewpoint of pack life because it is easy to take a large area.

As the spinning pack, one or a plurality of the metal fibers of the present invention can be used as a filter medium on a normal spinneret, and for example, a caulking ring can be used. Also preferred is a method for preventing gelation of polyhexamethylene adipamide resin by reducing the resin retention space by using sand or glass beads in the upper space of the filter medium and the resin inflow path, thereby reducing the melting time of the resin. .
More preferably, the metal fiber nonwoven fabric in the filter medium of the present invention contains molybdenum. Inclusion of molybdenum can further reduce the pack pressure increase rate of the spinning in the present invention. The molybdenum content is preferably 0 to 30 wt%. Inclusion of molybdenum is preferable because it can further suppress an increase in pack pressure during melt spinning and enables spinning for a long time. The molybdenum content is more preferably 10 to 30 wt%.

The melt spinning pack of the present invention essentially requires a spinneret and a filter medium containing nickel metal by metal fibers, and other members necessary for assembling the melt spinning pack may be used as they are.
The content of nickel and molybdenum can be measured by EDX.
The polyhexamethylene adipamide resin used in the present invention needs to have a relative viscosity of formic acid of 60 to 110 in order to obtain high strength and high toughness long fibers. The relative viscosity of formic acid of the present invention corresponds to a relatively high degree of polymerization, and a polymer obtained by polymerizing in a normal polymerization process and further solid-phase polymerized is preferable. Alternatively, melt spinning is preferably a process in which a continuous polymerization-direct spinning drawing process is directly connected. In order to increase the degree of polymerization, the polymerization conditions are important, but additives for suppressing thermal decomposition, for example, heat stabilizers and antioxidants may be added.

  It is necessary to add 1 to 300 ppm of phosphorus atoms as a polymerization catalyst or a heat resistance imparting agent to the polyhexamethylene adipamide fiber used in the present invention. Examples of the compound containing a phosphorus atom include inorganic and organic phosphoric acids and salts thereof, inorganic and organic phosphorous acids and salts thereof, and inorganic and organic hypophosphorous acids and salts thereof. The salt is mainly a salt with an alkali metal or an amine. Organic phosphoric acid is phosphoric acid having an alkyl group that may have a branched chain. Examples of the alkyl group include alkanes having 1 to 10 carbon atoms and phenyl groups. The phosphorus atom to be added is preferably 10 to 200 ppm.

Addition of copper halide to the polyhexamethylene adipamide resin used for melt spinning of the present invention is effective in improving heat resistance, and is preferable. The copper salts include inorganic copper salts such as copper iodide, copper bromide, copper chloride and copper pyrophosphate, organic copper salts such as copper acetate, copper stearate and copper isophthalate, inorganic copper salts and organic copper salts. And other copper complexes. Further, in addition to the copper salt, an alkali metal halide compound, for example, an alkali halide compound such as potassium iodide and potassium bromide, an alkali earth metal halide compound such as magnesium iodide and zinc chloride, and tetraiodobenzene And halogen-substituted aromatic hydrocarbon compounds. It is preferable to contain 1-100 ppm as a copper atom, and it is still more preferable to contain 3-30 ppm.
As the melt-spun filter material of the present invention, it is necessary to use a metal fiber non-woven fabric whose surface metal composition is 20 to 100 wt% nickel as measured with an energy dispersive X-ray analyzer and whose pore size is 10 to 100 μm. There is.

When the polyhexamethylene adipamide resin passes through the filter medium during spinning, the polyhexamethylene adipamide resin tends to contact and aggregate with the metal fiber nonwoven fabric of the filter medium. In the past, it has been assumed that a certain size of agglomerates of foreign matter accumulates in the voids of the filter medium and becomes clogged, leading to an increase in pack pressure. In order to prevent the occurrence of fluff in the resulting polyhexamethylene adipamide fiber, it has been thought that strengthening filtration has been effective in the past. The pressure approaches the upper limit and the spinning duration is shortened. Naturally, if the pore size of the metal fiber nonwoven fabric used for filtration is increased, the filtration becomes sweeter and the rate of increase in pack pressure can be suppressed. However, melt spinning under such sweet conditions cannot prevent the occurrence of fluff.
It has been found that the combination of the nickel metal fiber nonwoven fabric and the pore size in the present invention has a great effect of suppressing an increase in pack pressure during melt spinning and reducing the occurrence of fluff.

In the present invention, it is particularly effective for producing polyhexamethylene adipamide fibers having a high tensile strength of 5 to 10 cN / dtex.
The polyhexamethylene adipamide resin of the present invention may contain 0 to 100 ppm of titanium oxide.
The kind of titanium oxide may be either anatase type or rutile type, and those having an average particle diameter of 0.01 to 2 μm can be suitably used.

In the melt spinning using the spinning pack of the present invention, a polyhexamethylene adipamide resin having a high polymerization degree is spun at a melting temperature of 280 to 310 ° C. and stretched by a 2 to 4 stage stretching machine (including a heat set roll). Is possible. As the surface of the roll, a mirror surface or 1-12S satin can be used, and it is more preferable to combine 2-10S satin.
It is preferable to provide a spinning oil of 0.1 to 5 wt% or a single yarn entanglement of 1 to 30 co / m, which is necessary for normal use as polyhexamethylene adipamide fiber.
The pack pressure increase rate needs to be 0.03 to 0.2 MPa / (filter medium passing resin amount t / filter medium area m2). This figure shows the pressure increase curve over time when the horizontal axis indicates the total amount of resin passing through the area of the filter medium through which polyhexamethylene adipamide resin passes during normal melt spinning. Approximate to obtain the correlation, and obtain the slope of the straight line as the pack pressure increase rate.

If the pack pressure increase rate is less than 0.03, filtration is insufficient, and there is a problem that fluff generation increases. On the other hand, when the pack pressure increase rate exceeds 0.2, the pack pressure exceeds the upper limit of melt spinning in a short time, and therefore spinning for a long time becomes impossible.
In this case, the initial pack pressure is preferably 10 to 26 MPa. This initial pack pressure is related to the pore size of the filter medium, the discharge amount in melt spinning, and the polymer viscosity. If this value is less than 10 MPa, the pressure fluctuation of the extruder leads to uneven discharge amount, and the foreign matter removal effect in filtration Is not preferable. When the initial pack pressure exceeds 26 MPa, the pack pressure increase rate may not fall within the scope of the present invention, and a long spinning time may not be obtained.

  The filter medium of the present invention contains nickel and preferably molybdenum. The mechanism that makes it possible to hold down the fuzz and enable long-term melt spinning is not clear, but the gelled product formed in the melted polyhexamethylene adipamide resin and the nickel metal in which various additives contain nickel or molybdenum Polyhexamethylene adipamide resin that does not adhere to the metal surface and passes through it one after another because of its low interaction with the water (this is not a simple affinity but rather a difference in reactivity, that is, a difference in corrosivity) As a result, the gelled product is shredded by nickel or molybdenum metal fibers, and the increase in pack pressure is suppressed without accumulating and developing as a foreign material.

The present invention will be described based on examples.
(1) Measurement of nickel and molybdenum-containing wt% EMAX2770 (EDX) manufactured by Horiba, Ltd. was connected to a scanning electron microscope S2400 (SEM) manufactured by Hitachi, Ltd. for measurement. The measurement conditions were an acceleration voltage of 20 kV, a probe current of 0.1 nA, an electron beam incident angle of 90 degrees, an X-ray extraction angle of 30 degrees, and a measurement time of 100 seconds.
(2) by the detector and the photoelectric tube type fuzz measuring device fuzz measurement Kasuga Electric Works Ltd. FLUFF DETECTOR F6-A at a measuring speed 300 meters / min and the sensitivity volume 7.0 perform 3.5 million m measurement, per 10 ⁸ m Converted.
(3) Measurement of relative formic acid viscosity 8.4% by weight was dissolved in 90% formic acid, and the relative formic acid viscosity (hereinafter referred to as VR) was measured with an Ostwald viscosity tube at 25 ° C.
(4) Pore size measurement (JIS B 8356-2)
The pore size was measured using the first bubble point method.
(5) Pack pressure increase rate (MPa / (filter medium passing resin amount t / filter medium area m2) and initial pack pressure Using a diaphragm seal type pressure gauge, the pack pressure is measured over time, and the filter medium passing resin is simultaneously plotted on the vertical axis. A numerical value obtained by dividing the amount by the filter medium area is taken on the horizontal axis, the slope is obtained by the method of least squares, and the pack rise rate and the vertical axis intercept are taken as the initial pack pressure.

[ Reference Example 1, Examples 2 to 6, Comparative Examples 1 to 4]
Using polyhexamethylene adipamide with a relative formic acid viscosity of 85 containing 10 ppm phosphorus atoms, 15 ppm titanium dioxide, 80 ppm copper atoms and 1800 ppm iodine atoms and a relative viscosity of 85, the discharge rate per unit area of the filter medium was 300 ° C. 2.3 g / cm2 / min, extruded from a spinneret with a pore diameter of 0.25 mm, and after applying an oil agent of about 1% by weight, the film was stretched at a draw ratio of 4.5 times, and entangled to give 3000 m / min. A 235 dtex 72 filament polyhexamethylenediamine adipamide drawn yarn was produced under melt spinning conditions by a straight-winding method. The strength of the obtained drawn yarn was 8.6 cN / dtex. The pack pressure increase rate and initial pressure at this time, and the fluff of the obtained yarn were evaluated. Experiments were performed with different types and pack types of metal filter media. The results obtained are shown in Table 1.

As the bead pack configuration, 30-40 mesh pass glass beads were filled in the filtration layer, and as the leaf disc pack, a pack having four leaf discs was used.
As is apparent from Table 1, in the spinning pack of the present invention, the pack pressure suppression is sufficiently effective, and the fluff quality is not affected.
On the other hand, in the pack composed of the metal nonwoven fabric filter medium having a composition not within the scope of the claims, a rapid increase in pack pressure was observed. Further, when the filtration accuracy was lowered, the fluff quality was deteriorated, and conversely, when the filtration was too severe, a rapid increase in pack pressure was observed.

  In the melt spinning of polyhexamethylene adipamide resin, it can be used for a melt spinning pack having a long life, a low pack pressure increase rate, and hardly generating fuzz and a melt spinning method using the pack.

Claims (3)

It consists ing medium from metal fibers of the nonwoven fabric, the surface metal composition of the metal fiber nonwoven fabric, the measurement of an energy dispersive X-ray analyzer, nickel content 30 ~ 60 wt%, and molybdenum content 0~30wt %, A chromium content of 20 wt% or less, and the filter medium has a pore size of 10 to 100 μm. The following steps:
Formic acid relative viscosity of 60 to 110, a polyhexamethylene adipamide resin a phosphorus atom-containing 1～300Ppm, using melt spinning pack according to claim 1, pack pressure rise rate (MPa / (filter medium passing resin amount t / Filter medium area m ² )) is melt-spun under the condition of 0.03-0.2 ,
A process for melt spinning polyhexamethylene adipamide having a tensile strength of 5 to 10 cN / dtex. Using polyhexamethylene adipamide resin 0~400ppm containing titanium dioxide, melt spinning method of polyhexamethylene adipamide as claimed in claim 2.