JP2005105471A - Method for producing polyketone fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a method for producing a polyketone fiber in which (1) occurrence of an insoluble matter in a coagulating bath is suppressed and stable spinning is made possible and (2) lowering of tensile strength and tensile modulus and lowering of fatigue resistance are suppressed. <P>SOLUTION: The method for producing the polyketone fiber comprises steps for dissolving a polyketone in which ≥95 mol% of the recurring unit is represented by chemical formula (1) into a solvent composed of 50-80 wt.% aqueous solution of a metal salt in which the concentration of a zinc halide is ≥10 wt%, extruding the resultant polyketone solution from a spinneret into a coagulating bath under specific conditions, solidifying the polyketone solution into a fibrous shape and washing the coagulated fiber with water and comprises using a part or all of the washing liquid for adjusting metal salt concentration of the coagulating bath. In the production method, a part of the coagulating bath is pulled out and concentrated until the metal salt concentration becomes 50-80 wt% and used as a solvent for polyketone. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing polyketone fibers. More specifically, the present invention relates to a method for stably producing high-strength polyketone fibers at a low cost using cheaper equipment and reducing the amount of industrial waste discharged in the production process.

By polymerizing carbon monoxide and olefins such as ethylene and propylene using a transition metal complex such as palladium and nickel as a catalyst, a polyketone in which carbon monoxide and olefin are almost completely alternately copolymerized is obtained. Is known (Non-Patent Document 1).
In particular, polyketone consisting of repeating units of ethylene and carbon monoxide, like polyethylene and polyvinyl alcohol, has a molecular chain that can take a planar zigzag conformation, so that fibers with high tensile strength and high tensile modulus can be obtained. A fiber having the highest tensile elastic modulus retention and high dimensional stability at high temperatures can be obtained.
In recent years, as a reinforcing material for automobile tires, there has been an increasing demand for organic fibers having higher tensile strength and higher tensile modulus and excellent tensile modulus retention at high temperatures. Such a fiber is used, for example, to improve the global environment by achieving weight reduction of the tire and improving the fuel efficiency of the automobile while maintaining the excellent performance of the steel tire cord.

The aramid fiber is an organic fiber having excellent performance for the above-mentioned purposes, but has a high fiber cost and has not yet been widely spread as a tire cord. Because polyketone fibers are obtained from inexpensive monomer raw materials of ethylene and carbon monoxide, it is possible to provide organic fibers that are low in cost, have high tensile strength and high tensile modulus, and have excellent tensile modulus retention at high temperatures. It is expected to be
In Patent Documents 1 and 2, for example, polyketone is dissolved using an aqueous solution of a metal salt such as zinc salt or calcium salt as a solvent, and the polyketone solution is extruded from a spinneret into a coagulation bath and formed into a fiber (wet spinning). In addition, a method for industrially producing a polyketone fiber having high tensile strength and high tensile elastic modulus by thermally stretching it is disclosed. Further, it is disclosed that a metal salt aqueous solution containing zinc halide represented by zinc chloride has high solubility of polyketone, is inexpensive, and is excellent as an industrial solvent. However, in order to produce a polyketone fiber having a high tensile strength and a high tensile elastic modulus at low cost stably for a long period of time, further improvement of the wet spinning technique was required.

The metal salt used as the polyketone solvent is extracted from the polyketone solution in a coagulation bath and used again as a solvent. For this reason, it is advantageous to use an aqueous solution made of the same metal salt as the solvent for the coagulation bath because the cost for regenerating as a solvent is low. However, when such a coagulation bath is used, a modified product of zinc halide insoluble in the coagulation bath is generated, which may cause thread breakage and decrease the yield.
Patent Document 3 discloses that by adding an acid to the coagulation bath and maintaining the pH to be 6 or less, generation of the aforementioned modified product is prevented and the frequency of yarn breakage is reduced. However, subsequent studies have revealed that the following problems may occur when the disclosed method is industrially used as it is.

When the disclosed coagulation bath is concentrated as it is and used as a solvent, the tensile strength may decrease or the fatigue resistance may decrease when used as a rubber reinforcing material. In particular, as disclosed in Patent Document 2, a polyketone fiber having higher tensile strength and tensile elastic modulus by wet spinning using a polyketone solution in which a phase separation phenomenon is observed in an appropriate temperature range as a spinning dope It was found to be remarkable in the production method for obtaining
Patent Document 3 discloses a method of neutralizing a coagulation bath to which an acid has been added as described above with a base such as zinc hydroxide and then reusing it as a solvent. However, this method requires complicated equipment for neutralization and increases costs. Neutralization generates modified zinc halides, and the zinc halide modified products settle and adhere in tanks and pipes when operated for long periods of time during the neutralization and concentration process. Therefore, it has been found that there is a problem that the cost due to cleaning and repair increases.

Moreover, in the cleaning process after coagulation, in addition to the extraction of the solvent in the coagulation bath, the metal salt is further recovered to keep the metal salt from being discharged out of the production process. Is important. However, no cleaning method considering efficient recovery of metal salts is disclosed.
Industrial Materials, December 1997, p5 International Publication No. 00/09611 Pamphlet International Publication No. 02/068738 Pamphlet JP 2001-146541 A

The purpose of the present invention is to
1) A method for producing polyketone fibers, which can suppress the generation of insoluble matter in the coagulation bath and can be stably spun.
2) A method for producing a polyketone fiber in which a decrease in tensile strength and tensile modulus and a decrease in fatigue resistance are suppressed when the coagulation bath liquid is concentrated and reused as a solvent,
3) In the washing process after solidification, it is possible to extract and recover the metal salt at a low cost and with a high yield, and it is possible to reduce the metal salt discharged out of the manufacturing process and to reduce the manufacturing cost. Method for producing a polyketone fiber,
Is to provide.

  In order to solve the above problems, the present inventors have studied a method for suppressing the modified zinc halide generated in the coagulation bath, efficiently recovered the coagulation bath, concentrated it at low cost, and re-used it as a solvent. Examination of the method to be used and the method of suppressing the decrease in fiber properties when the coagulation bath was concentrated and reused as a solvent were investigated. As a result, the above problems can be solved by using a coagulation bath with an appropriate range of metal salt concentration and pH, washing the fiber after coagulation with water, and adjusting the metal salt concentration of the coagulation bath with the washing solution. As a result, the present invention has been completed.

That is, the present invention is as follows.
(1) A polyketone in which 95 mol% or more of the repeating units is represented by the chemical formula (1) is a 50-80 wt% metal salt aqueous solution, and the zinc halide concentration is 10 wt% or more. The resulting polyketone solution is extruded from a spinneret into a coagulation bath satisfying the following conditions (A) to (C), solidified into a fiber, and the coagulated fiber is washed with water. A part or all of the cleaning liquid is used to adjust the metal salt concentration of the coagulation bath, and a part of the coagulation bath is extracted and concentrated until the metal salt concentration becomes 50 to 80 wt%. A process for producing a polyketone fiber, characterized by being used as a solvent for polyketone.
(A) A metal salt aqueous solution composed of the same metal salt as the solvent.
(B) Metal salt concentration is 1-30 wt%.
(C) The pH is 4.5 to 5.5.

(2) The method for producing a polyketone fiber according to (1), wherein the polyketone solution has a phase separation temperature in a temperature range of 0 to 150 ° C.
(3) The method for producing a polyketone fiber according to (1) or (2), wherein the concentration of zinc halide as a solvent is 10 to 30 wt%.
(4) The method for producing a polyketone fiber according to any one of (1) to (3), wherein the zinc halide is zinc chloride.
(5) The method for producing a polyketone fiber according to any one of (1) to (4), wherein the metal salt of the solvent is a mixture of zinc chloride, calcium chloride and lithium chloride.
(6) The amount of water used for washing the coagulated fibers (W, the unit is g / min) is in the range shown in Formula (1), and the amount of residual metal salt in the fibers washed with the amount of water is 20 wt% or less. The method for producing a polyketone fiber according to any one of (1) to (5), wherein:

(Wherein A is the metal salt concentration (wt%) of the solvent, B is the metal salt concentration (wt%) of the coagulation bath, C is the discharge rate of the spinning dope (g / min), and P is the polymer concentration of the spinning dope ( wt%).)
(7) The metal salt aqueous solution is squeezed from the coagulated fiber by sandwiching the coagulated fiber between two rolls arranged in parallel, and the metal salt aqueous solution is returned to the coagulation bath (1) to (6) The manufacturing method of the polyketone fiber of any one of.
(8) After washing the coagulated fiber with water, the washing solution is squeezed out from the fiber by sandwiching the fiber between two rolls arranged in parallel, and a part or all of the washing solution is concentrated in the metal salt concentration of the coagulation bath. The method for producing a polyketone fiber according to any one of (1) to (7), wherein the method is used for the adjustment of.
(9) The polyketone fiber according to any one of (1) to (8), wherein the coagulated fiber is washed with water by running the fiber in a water bath in which bubbles are generated from below. Method.
(10) A part of the coagulation bath is extracted and concentrated to a metal salt concentration of 50 to 80 wt% using a multi-effect evaporation concentrator, and used as a polyketone solvent (1) to The manufacturing method of the polyketone fiber as described in any one of (9).

  According to the method for producing a polyketone fiber of the present invention, spinning can be stably performed, and a polyketone fiber having high tensile strength and tensile elastic modulus can be stably obtained. In addition, it is possible to reduce the amount of metal salt, which is a solvent, out of the manufacturing process, there is no environmental problem around the factory, and the manufacturing cost can be reduced.

  In the polyketone of the present invention, 95 mol% or more of the repeating units are represented by the chemical formula (1). Other than the chemical formula (1), for example, a repeating unit represented by the chemical formula (2) may be contained within a range of less than 5 mol%.

  (In the formula, R is an organic group having 1 to 30 carbon atoms other than ethylene, for example, a hydrocarbon group such as propyl, butyl, etc. Some or all of these hydrogen atoms are halogen groups or ester groups. The polyketone molecule may contain two or more units having different R, for example, R is a mixture of a propyl group and a butyl group. A polyketone in which 97 mol% or more of the repeating unit is represented by the chemical formula (1) from the viewpoint that a higher tensile strength and a higher tensile elastic modulus can be achieved and the strength and the elastic modulus retention at high temperatures are excellent. Preferably, it is 100 mol%.

The intrinsic viscosity [η] of the polyketone of the present invention tends to obtain a higher strength and elastic modulus of the polyketone fiber as the value is larger, and is preferably 3 dl / g or more. However, when [η] exceeds 20 dl / g, the solubility and spinnability tend to be deteriorated, so 20 dl / g or less is preferable. A more preferable range of [η] is 3 to 18 dl / g, most preferably 5 to 15 dl / g.
As a method for producing a polyketone used as a raw material for the polyketone fiber, a known method or a modification thereof can be used.
The polyketone is dissolved in a solvent composed of a 50-80 wt% metal salt aqueous solution and a zinc halide concentration of 10 wt% or more to form a spinning dope.

  Specific examples of the zinc halide include zinc chloride, zinc bromide, zinc iodide and the like. Zinc chloride is preferred because the metal salt is stable and inexpensive. Zinc chloride that is industrially available at low cost may contain an ammonium salt such as ammonium chloride. The higher the ammonium salt content, the easier the polyketone is modified during dissolution, and the lowering of the strength of the polyketone fiber and the increase in fluff are likely to occur.

  Zinc chloride using zinc oxide and hydrochloric acid as raw materials is preferable because the content of ammonium salt is small. Zinc oxide is defined in the product standard of JIS-K1410, and the classification is classified into one type, two types, and three types according to zinc oxide purity, lead content, and the like. For example, there are one type when the lead content is 0.005 wt% or less, two types when the lead content is 0.03 wt% or less, and three types when the lead content is 0.3 wt% or less. One kind of zinc oxide is preferable in that there are few impurities such as lead. Hydrochloric acid is water in which hydrogen chloride produced by combustion and combination of chlorine and hydrogen generated in an electrolytic cell is absorbed by water, but hydrogen chloride generated by organic synthesis chlorination reactions such as methyl chloride and chlorobenzene is converted to water. It may be absorbed. An aqueous solution of zinc chloride can be obtained by adding and dissolving zinc oxide having a mole number ½ times that of hydrogen chloride in 0.1 to 35 wt% hydrochloric acid.

  The metal salt other than zinc halide constituting the metal salt aqueous solution is not limited as long as it is soluble in water. When an anionic element is used in common, there is an advantage that the composition can be adjusted at a low cost when the solvent is recovered and reused. Accordingly, metal halide salts are preferred. Specific examples include sodium chloride, calcium chloride, lithium chloride, barium chloride, sodium bromide, calcium bromide, lithium bromide, barium bromide, sodium iodide, calcium iodide, lithium iodide, barium iodide, and the like. Can be mentioned. For example, a combination of zinc chloride and one selected from calcium chloride, sodium chloride, lithium chloride and barium chloride is preferred, and a mixture of zinc chloride, calcium chloride and lithium chloride is preferred.

  The metal salt concentration of the solvent is 50 to 80 wt%, and the concentration of zinc halide is 10 wt% or more. When the metal salt concentration is less than 50 wt%, or when the zinc halide concentration is less than 10 wt%, the solubility of the polymer deteriorates, so that stable spinning becomes difficult, and a stable and high-strength polyketone fiber is obtained. Absent. If the metal salt concentration exceeds 80 wt%, it is difficult to stably obtain a high-strength polyketone fiber due to precipitation of the metal salt. The metal salt concentration of the solvent is preferably 55 to 75 wt%, more preferably 60 to 65 wt%.

  The concentration of zinc halide is 80 wt%, that is, zinc halide such as zinc chloride alone can be dissolved and spun in the polyketone. However, since the polyketone solution has slightly low spinnability, single yarn breakage may occur when spinning at high speed for a long period of time. On the other hand, when zinc halide and a metal salt other than zinc halide are mixed, the spinnability of the polyketone solution is increased, so that stable spinning at high speed is possible and higher tensile strength and tensile strength are achieved. It becomes possible to stably obtain a polyketone fiber having an elastic modulus. Therefore, when a higher spinning speed is required, the zinc halide concentration is preferably 60 wt% or less, and more preferably 50 wt% or less. Further, as will be described in detail later, the zinc halide concentration is most preferably 30 wt% or less from the viewpoint of easily suppressing problems associated with the generation of a modified zinc halide insoluble in the coagulation bath.

  The concentration of the metal salt aqueous solution and the zinc halide concentration mentioned here are values defined by the following mathematical formulas (2) and (3).

  The polymer concentration in the spinning dope of the present invention is preferably 0.1 to 40 wt%. If the polymer concentration is less than 0.1 wt%, it may be difficult to form a fiber in the spinning process because the concentration is low. On the other hand, if it exceeds 40 wt%, the polymer is difficult to dissolve in the solvent. From the viewpoint of the solubility of the polymer, the ease of spinning, and the production cost of the fiber, it is preferably 1 to 30 wt%, more preferably 3 to 20 wt%. The polymer concentration here is a value defined by Equation (4).

  The polyketone can be dissolved by a general method in which a polyketone and a solvent are put into a dissolver and stirred to obtain a uniform spinning solution. As the dissolver, a known one having a uniaxial or biaxial stirring blade and excellent in stirring efficiency can be applied. As a uniaxial stirring dissolver, one having a spiral or double spiral blade is suitable. For example, a planetary mixer, a double-arm kneader, a Banbury mixer, etc. having a rotating and revolving hook as a stirring blade are applied as the biaxial stirring batch type melting machine. As the continuous melting machine, for example, screw extrusion Machines and coniders are applied.

  The spinning dope preferably has a phase separation temperature in the temperature range of 0 to 150 ° C. from the viewpoint that polyketone fibers having higher strength and higher elastic modulus can be easily obtained. The phase separation temperature is more preferably 100 ° C. or less, and most preferably 60 ° C. or less in that the polyketone solution can be stably discharged from the spinneret for a long period of time. The phase separation temperature is more preferably 10 ° C. or higher in that the solidification rate can be increased and the spinning rate can be increased.

The phase separation temperature is a temperature at which when the spinning stock solution dissolved substantially uniformly is gradually cooled, the polyketone does not dissolve in the solvent and the spinning stock solution starts to be in a non-uniform state. This non-uniform state can be determined by light transmittance. If the spinning stock solution becomes non-uniform, light scattering increases and the solution becomes white and opaque.
In the present invention, when the polyketone solution substantially uniformly dissolved (the light transmittance in the solution at this time is the initial transmittance) is gradually cooled at a speed of 10 ° C. per hour (at this time) The temperature at which the reduction rate of the light transmittance becomes 10% is defined as the phase separation temperature. A method for measuring the light transmittance will be described later. The light transmittance decrease rate is a value defined by Equation (5).

The phase separation temperature varies depending on the metal salt composition of the solvent, the polymer concentration and the polymer molecular weight, and the spinning dope having a phase separation temperature in the temperature range of 0 to 150 ° C. is the type of metal salt, metal salt composition, metal salt concentration, This can be achieved by adjusting the polyketone concentration and [η] of the polyketone.
As a preferred composition of the spinning dope, for example, the metal salt is calcium chloride and zinc chloride, and the mass ratio is 68.0 / 32.0 to 61.0 / 39.0 (calcium chloride / zinc chloride), metal The salt concentration of the aqueous salt solution is 59.0 to 64.0 wt%, the [η] of the polyketone is 5 to 10, and the polymer concentration is 5 to 10 wt%.

As another example, the metal salt is calcium chloride, zinc chloride, and lithium chloride, and the mass ratio of calcium chloride + lithium chloride and zinc chloride is 68.0 / 32.0-61.0 / 39.0 (salt chloride). Calcium + lithium chloride / zinc chloride), the mass ratio of calcium chloride to lithium chloride is 90/10 to 65/35 (calcium chloride / lithium chloride), the salt concentration of the aqueous metal salt solution is 59.0 to 64.0 wt%, [Η] of the polyketone is 5 to 10, and the polymer concentration is 5 to 10 wt%. The metal salt is preferably zinc chloride, calcium chloride and lithium chloride in that a polyketone fiber having higher tensile strength can be obtained.
The above spinning dope is discharged from the spinneret through a process such as filtration as necessary through a pipe from a dissolver by a gear pump or the like. The discharged spinning solution is solidified in a coagulation bath to form coagulated fibers.

The coagulation bath needs to satisfy the following conditions (A) to (C).
(A) An aqueous metal salt solution comprising the same metal salt as the solvent.
(B) Metal salt concentration is 1-30 wt%.
(C) The pH is 4.5 to 5.5.
The coagulation bath is an aqueous metal salt solution made of the same metal salt as the solvent. Therefore, it is possible to extract the metal salt from the spinning dope in a coagulation bath, remove the water from the coagulation bath and concentrate it, and use it again as a solvent. When the metal salt of the solvent and the metal salt of the coagulation bath are different, when the coagulation bath is an organic solvent other than water, such as methanol, separation of the metal salt and separation of water and the organic solvent are required. Therefore, the equipment cost, the energy and the proportional cost of the drug are increased, and the cost advantage over the aramid fiber is reduced.

  When the coagulation bath is a metal salt aqueous solution composed of two or more kinds of metal salts, the mass ratio of the metal salts is preferably close to that of the solvent. In order to concentrate the coagulation bath and use it again as a solvent, adjustment may be necessary when the mass ratio of the metal salt is greatly different, increasing the equipment cost and the metal salt cost. Specifically, in the solvent and the coagulation bath, the difference in mass ratio (wt%) of one kind of metal salt arbitrarily selected with respect to all metal salts is preferably 3 wt% or less, more preferably 1 wt% or less.

  The concentration of the metal salt aqueous solution in the coagulation bath is 1 to 30 wt%, preferably 3 to 20 wt%, more preferably 5 to 15 wt%. If the concentration of the aqueous metal salt solution is less than 1 wt%, when a part of the coagulation bath is extracted and concentrated until the metal salt concentration reaches 50 to 80 wt% and used again as a solvent, the cost of removing and concentrating water is high. Become. If the concentration of the metal salt aqueous solution exceeds 30 wt%, the physical properties of the fiber will decrease, and the extraction of the metal salt in the coagulation bath will be less, so the proportion of the metal salt that will be reused as a solvent will decrease, increasing the manufacturing cost. There arises a problem that the amount of the metal salt discharged outside the manufacturing process becomes large.

  The pH of the coagulation bath is 4.5 to 5.5. If the pH exceeds 5.5, denatured zinc halide insoluble in the coagulation bath may be generated, for example, clogging the pump in the device for adjusting the metal salt concentration of the coagulation bath, the device for concentrating the coagulation bath, etc. In addition, since the denatured zinc halide precipitates and adheres in tanks and pipes, the cost for cleaning and repair increases. Further, the modified product adheres to the yarn path, which causes a problem of yarn breakage. On the other hand, in the case of less than 4.5, the generation of a modified zinc halide is not seen, but when a part of the coagulation bath is extracted, concentrated as it is, and the polyketone is dissolved again as a solvent to perform spinning. The tensile strength of the polyketone fiber after hot drawing is lowered.

When the pH exceeds 5.5, the acid can be added to the coagulation bath, and when the pH is less than 4.5, the pH of the coagulation bath can be adjusted by adding a base.
Examples of the acid include hydrogen halide, sulfuric acid, phosphoric acid, and carbonic acid. Examples of the base include zinc hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, zinc oxide, calcium oxide and the like. If the metal salt of the solvent is zinc chloride, the acid is preferably hydrogen chloride and the base is preferably zinc hydroxide, considering that a part of the coagulation bath is extracted, concentrated as it is, and used again as a solvent. If the metal salt of the solvent is zinc chloride, calcium chloride or lithium chloride, the acid is preferably hydrogen chloride, and the base is preferably zinc hydroxide, calcium hydroxide or lithium hydroxide.

  The temperature of the coagulation bath is preferably 30 ° C. or lower because the achieved strength after stretching is high. When the phase separation temperature is present in the spinning dope, it is preferably not higher than the phase separation temperature, and more preferably 30 ° C. lower than the phase separation temperature. However, when the temperature of the coagulation bath is lower than −50 ° C., the temperature is preferably −50 ° C. or higher from the viewpoints that the coagulation speed is reduced and the spinning speed cannot be increased, and the cooling cost is increased.

In the present invention, the coagulated fiber solidified in the coagulation bath is washed with water, and part or all of the washing solution is used for adjusting the concentration of the coagulation bath.
In the coagulation bath, the metal salt is extracted from the polyketone solution discharged from the spinneret, so that the metal salt concentration in the coagulation bath increases. When spinning in such a state, the coagulation state in the coagulation bath changes with the lapse of the spinning time, and thus there may be problems such as variations in tensile strength after hot drawing and the occurrence of fluff. is there.

In order to keep the metal salt concentration of the coagulation bath constant, the coagulation bath is diluted with water or an aqueous metal salt solution having a low concentration. At this time, by washing the coagulated fiber with water and diluting with a part or all of the washing liquid, it becomes possible to reduce the amount of metal salt discharged out of the manufacturing process. There is a big effect in terms of cost.
The metal salt concentration in the coagulation bath can be adjusted by a method of diluting with water or the above-described cleaning solution while measuring the metal salt concentration in the coagulation bath with a density meter. The difference between the upper limit and the lower limit of the metal salt concentration in the coagulation bath is preferably 5 wt% or less, more preferably 3 wt% or less, and most preferably 1 wt% or less.

The amount of impurities in the water used in the present invention is preferably 0.01 wt% or less, more preferably 0.005 wt% or less, and most preferably 0.001 wt% or less. The pH is preferably 4.5 to 8.0, more preferably 5 to 8, and most preferably 6 to 8. If the amount of impurities and pH of water deviate from the above ranges, the extracted coagulation bath is concentrated until the metal salt concentration becomes 50 to 80 wt% and repeatedly used for spinning over a long period of time. Thread breakage or thread breakage may occur.
In the present invention, washing the coagulated fiber with water means that the cleaning agent supplied to the washing step is water. For example, when the solidified fiber is passed through the washing bath and washed, the liquid in the washing bath may be different from water because the metal salt is extracted from the solidified fiber in the washing bath. The washing | cleaning liquid newly supplied in a bath should just be water. The coagulated fiber may be directly brought into contact with water without passing through the washing bath.

  The amount of water used for washing is increased in that the proportion of wash water that can be used to adjust the concentration of the coagulation bath is increased, and the amount of metal salt discharged outside the metal salt production process can be reduced. Is preferably less. However, it is preferable that the amount of water used for washing is large in that the metal salt is extracted from the coagulated fiber and washed efficiently. The amount of water for adjusting the metal salt concentration by diluting the coagulation bath is related to the metal salt concentration of the solvent, the metal salt concentration of the coagulation bath, the discharge amount of the spinning dope, and the polymer concentration of the spinning dope. From these relationships, it is possible to define a preferable range of the amount of water used for washing the coagulated fibers. The amount of water (W, the unit is g / min) used for washing the coagulated fibers is preferably in the range of the value represented by Formula (1), and more preferably in the range represented by Formula (6).

(Wherein A is the metal salt concentration (wt%) of the solvent, B is the metal salt concentration (wt%) of the coagulation bath, C is the discharge rate of the spinning dope (g / min), and P is the polymer concentration of the spinning dope ( wt%).)
When the amount of water (W) exceeds the upper limit value (the right side of the formula), the ratio that can be used for dilution of the coagulation bath decreases, and the energy cost for concentration increases when the remainder is sent to the step of concentrating. When the amount of water (W) is less than the lower limit value (the left side of the formula), the cleaning efficiency is lowered, and the ratio of reusing the metal salt as a solvent is lowered.

  The method of washing the coagulated fiber with water includes a method of passing the coagulated fiber in a bath, a method of spraying water from above and / or below the coagulated fiber, a method of spraying water on the coagulated fiber on a roll, etc. You may combine methods. Washing in a state where the single yarns are separated one by one and the fibers are spread as much as possible increases the efficiency of extracting the metal salt from the coagulated fibers, which is preferable. In the case of passing the coagulated fiber through the bath, bubbles are generated from the bottom of the bath, foam is applied to the running fiber to spread the fiber, and a fixed guide or roll guide is provided in the bath to squeeze and spread the fiber. The method is preferred because the fibers spread in the bath.

Bubbles in the bath can be generated by sinking a pipe having pores below the bath and sending air into the pipe. The size and amount of bubbles can be appropriately adjusted according to the size and number of pores provided in the pipe, the amount of air to be sent, the pressure, and the like. By appropriately adjusting the size and amount of foam and the tension of the fiber, it is possible to efficiently open the coagulated fiber.
As described above, in order to wash the coagulated fiber with a limited amount of water, the metal salt aqueous solution attached to the coagulated fiber with a wind of pressure or the like after the coagulated fiber is pulled up from the coagulation bath and washed with water. It is possible to wash with less water by returning the metal salt aqueous solution to the coagulation bath by squeezing out the metal salt aqueous solution from the coagulated fiber by sandwiching it between two rolls arranged in parallel. This is preferable.

  In order to reduce the pressure for sandwiching the coagulated fibers between the rolls as much as possible, to suppress damage to the coagulated fibers and to maintain the squeezing effect, either one of the rolls made of a material having a water absorbing surface is used. It is preferable to use both. In addition, the ability to remove the metal salt aqueous solution by sandwiching the solidified fiber with a roll having elasticity on the surface water-absorbing material has a higher ability to remove the metal salt aqueous solution, and less damage to the fiber. And more preferable.

  The material having water absorption is not limited as long as it is capable of sucking water by capillary action, such as sponge, woven fabric, knitted fabric, and non-woven fabric. In the case of a sponge, one having a small gap, and in the case of a woven fabric, a knitted fabric, or a non-woven fabric, a thin single fiber and a large basis weight are preferable in terms of increasing water absorption. As the material having elasticity, a sponge is preferable. However, a woven fabric, a knitted fabric, a nonwoven fabric, and the like can obtain the same effect by providing an elastic material such as urethane, rubber, or sponge on the inside. The metal salt aqueous solution sucked by the material having water absorption can be recovered by a method such as compressing and squeezing with a roll or the like, or sucking from the inside of the roll. The metal salt aqueous solution recovered by removing from the coagulated fibers is sent to a coagulation bath and / or a concentration facility, and can be reused as a solvent.

Furthermore, in order to suppress damage to the fiber and suppress the occurrence of fluff and the decrease in strength, the coagulated fiber is brought into contact with the coagulated fiber on the roll using a roll made of a material having a water absorbing surface. You may employ | adopt the method of removing metal salt aqueous solution from.
After washing the coagulated fibers with water, the fibers are sandwiched between two rolls arranged in parallel to squeeze the washing liquid from the fibers, and part or all of the washing liquid is used to adjust the metal salt concentration in the coagulation bath. It is preferable to use it. The metal salt in the cleaning liquid can be reused as a solvent, and the amount of the metal salt discharged out of the manufacturing process can be further reduced. As the apparatus and method, the same apparatus and method as those described above can be applied.

In the case of two or more kinds of metal salts, the mass ratio of the metal salts is adjusted as necessary. In the coagulation bath extracted from the solvent, the difference in the mass ratio (wt%) of one kind of metal salt arbitrarily selected with respect to all metal salts is preferably 3 wt% or less, more preferably 1 wt% or less.
The extracted coagulation bath liquid removes, for example, oligomers, polymerization catalysts, additives, metals such as iron derived from equipment materials, and the like mixed in the coagulation bath.

  The coagulation bath solution adjusted as described above is concentrated until the metal salt concentration becomes 50 to 80 wt%. As a method for concentrating the coagulation bath liquid, a method of evaporating water, a method using a reverse osmosis membrane, a method using an ion exchange membrane, a method combining these, and the like are used. A method of evaporating moisture is preferable in that it is possible to suppress a change in the mass ratio of the metal salt and that the cost for concentration to a metal salt concentration of 50 wt% or more is low. Although there is no restriction | limiting in the apparatus which evaporates a water | moisture content, It is preferable to concentrate using a multi-effect evaporative concentration apparatus at a point with low running cost. A known multi-effect evaporation concentrator can be used.

Next, a double effect can evaporating and concentrating apparatus will be described. The extracted coagulation bath is supplied to an evaporator (first evaporator), and water is evaporated by heating. Supply the coagulation bath concentrated in the first evaporator to the next evaporator (second evaporator), use the vapor generated in the first evaporator as a heat source in the second evaporator, and perform further concentration, Obtain the desired concentrate.
As described above, the multi-effect concentrator can reduce the running cost by efficiently using steam as a heat source, and the running cost becomes lower as the number of effect evaporators increases. Considering that the equipment cost increases as the number of evaporators increases, the number of utility evaporators is preferably 2 to 6, and more preferably 3 to 5.

Next, the manufacturing process after washing the coagulated fiber with water will be described.
If necessary, washing is further performed to remove metal salts in the fiber. As the cleaning agent, water or an aqueous solution having a pH of 4 or less containing hydrochloric acid, sulfuric acid, phosphoric acid and the like can be used.
It is preferable to dry in order to remove moisture before hot stretching. As an apparatus for drying, known equipment such as a tunnel dryer, a roll heater, and a net process dryer is used. The drying temperature is preferably 150 to 250 ° C. in that a polyketone fiber having high strength can be obtained.
Polyketone fibers having high strength and elastic modulus can be obtained by hot-drawing the fibers thus obtained. The thermal stretching may be performed at a temperature of 100 to 300 ° C., and the number of stretching stages may be performed in one stage, or may be performed in multiple stages by gradually increasing the stretching temperature. Multi-stage stretching is preferred in that the total stretching ratio can be increased and the stretching speed can be increased. The total draw ratio is preferably 10 times or more, more preferably 12 times or more, and most preferably 15 times or more because fibers having high strength and high modulus can be easily obtained.

  The heat stretching can be performed, for example, by heating the fiber between the speed regulating rolls of the feed roll and the take-up roll. The number of combinations is the number of stages of hot stretching. As a method of heating the fiber, a known method such as a method of running in a heated gas using a hot roll, a hot plate, or a heating furnace, a method of heating the fiber by irradiating a laser, microwave, or infrared ray is used. It can be employed as is or modified.

Hereinafter, the present invention will be described specifically by way of examples. They do not limit the scope of the present invention.
The measuring method used in the present invention is as follows.
(1) pH measurement of coagulation bath Measured using a pH meter PH82-32 manufactured by Yokogawa Electric Corporation at a temperature of 3 ° C.
(2) Intrinsic viscosity Intrinsic viscosity [η] is determined based on the following defining formula.
[Η] = lim (T−t) / (t · C)
C → 0
In the formula, t and T are the flow times of a viscosity tube at 25 ° C. of hexafluoroisopropanol (manufactured by Central Glass Co., Ltd.) and a dilute solution of polyketone dissolved in the hexafluoroisopropanol, respectively. C is the concentration of the diluted solution, and is the mass (g) of polyketone in 100 ml of hexafluoroisopropanol.

(3) Tensile strength, tensile elongation, and tensile modulus of fiber Measured according to JIS-L-1013.
Sample length: 20 cm, tensile speed: measured at 20 cm / min, and an average value is obtained when measured 20 times.
(4) Phase separation temperature When the dissolved polyketone solution (the light transmittance in the solution at this time is the initial transmittance) is gradually cooled at 10 ° C./hr (light transmission in the solution at this time). The temperature when the rate of decrease in light transmission is 10% is defined as the phase separation temperature.
The measurement temperature range is from 0 ° C. to the dissolution temperature, and when it is less than 0 ° C., there is no phase separation temperature. Further, the light transmittance decrease rate is a value defined by the following equation.
Reduction rate of light transmittance (%) = [(initial transmittance−transmittance) / initial transmittance] × 100
The light transmittance is measured using a laser type light scattering photometer LSD-101 (manufactured by Nihon Kagaku Engineering Co., Ltd.) with a sample cell unit capable of controlling heating and cooling. The light source is a He-Ne laser with a wavelength of 632.8 nm, the output is 15 mW, and the beam diameter is 1.50 mm (at 1 / e ² ).

(5) Measurement of solidified fiber and amount of metal salt remaining in fiber after washing 10 g of fiber is collected, placed in 500 mL of 0.1 wt% hydrochloric acid, and left for 24 hours to extract the metal salt in the fiber. The concentration of the metal salt contained in the extract is measured by high frequency plasma emission spectrometry. Next, the fiber is taken out, sufficiently washed with running water, dried at 105 ° C. for 5 hours to remove moisture, and the mass of the fiber is measured. From the above metal salt concentration and fiber mass, the amount of metal salt contained in the coagulated fiber and the washed fiber is calculated.
(6) Belt Fatigue Evaluation After blending five obtained polyketone fibers, using a twisting machine (manufactured by Kaji Iron Works Co., Ltd.), both the lower twist (Z direction) and the upper twist (S direction) are 390. Twist / m twisted yarn to obtain a twisted cord. This is treated with resorcin-formalin-latex liquid (resorcin 22 wt part, 30 wt% formalin aqueous solution 30 wt part, 10 wt% sodium hydroxide aqueous solution 14 wt part, water 570 wt part, vinylpyridine latex 41 wt part), and RFL treatment code and To do.

  Next, the obtained RFL-treated cords were arranged in two layers at the top and bottom at 25 / inch in an unvulcanized rubber compounded with natural rubber 70 wt%, SBR 15 wt%, and carbon black 15 wt%, and vulcanized (vulcanized) Conditions: 135 ° C., 3.5 MPa, 40 minutes), and a belt having a thickness of 8 mm is obtained. Using this belt, a compression / bending fatigue test is performed according to JIS-L1017-2.1 (Firestone method) (load: 50 kg, belt reciprocating speed: 100 rpm, reciprocating frequency: 20000 times, compressibility: 85%. ). After the test is completed, the cord is taken out from the belt, the tensile strength retention rate (%) with respect to the cord before the fatigue test is obtained, and the fatigue resistance is evaluated.

[Example 1]
Metal salt aqueous solution having a metal salt concentration of 10 wt%, a metal salt composed of zinc chloride, calcium chloride, and lithium chloride, and a mass ratio of zinc chloride / calcium chloride / lithium chloride = 22/30/10 A solution to which hydrochloric acid was added so that the pH was 5.0 was prepared as a coagulation bath. A part of this coagulation bath was heated under reduced pressure at 100 ° C. to concentrate the metal salt concentration to 62 wt%. When this concentrated solution was returned to a metal salt concentration of 10 wt% and pH was measured, there was no change at 5.0. It indicates that hydrochloric acid added by adjusting the pH remains without being azeotroped with water in the concentration operation.
Using this concentrated solution as a solvent, a polyketone having an intrinsic viscosity of 5.5 dl / g and substantially 100 mol% of repeating units represented by the chemical formula (1) was dissolved.

  A polyketone was mixed at a temperature of 80 ° C. so that the polymer concentration became 7.5 wt%, and stirred for 3 hours while depressurizing to 6.7 kPa to obtain a uniform and transparent polyketone solution. The mass ratio of metal salt to polyketone in this polyketone solution was 7.65. A part of this polyketone solution was transferred to a sample cell, and light transmittance was measured while cooling the temperature of the solution from 85 ° C. at a rate of 10 ° C. per hour. The phase separation temperature of this polyketone solution was 42 ° C.

  Using this polyketone solution as a spinning solution, spinning was performed using the spinning device shown in FIG. The polyketone solution was discharged from a spinneret 1 having 250 holes having a diameter of 0.18 mm at 145 g / min at 80 ° C. It passed through the coagulation bath 2 (capacity: 200L) adjusted to the temperature of 1-2 degreeC through the air gap of length 10mm at 20 m / min, and the coagulated fiber was obtained. At this time, the mass ratio of metal salt to polyketone (hereinafter referred to as residual salt mass ratio) in the coagulated fiber was 1.63. Next, when the squeeze roll 6 was passed at 20 m / min, the residual salt mass ratio in the coagulated fiber was 1.25. The aqueous metal salt solution extracted by the squeezing roll was returned to the coagulation bath adjustment tank 4 (capacity: 400 L).

Subsequently, the washing bath 8 (4 m) was passed at a speed of 20 m / min. At this time, the flow rate (W) of water supplied to the washing bath 8 was adjusted to 700 g / min by the flow rate adjusting device 12. In the spinning conditions of Example 1, the range of W in the formula (1) is 349 ≦ W ≦ 2092 g / min, and the range of W in the formula (6) is 349 ≦ W ≦ 1395 g / min. The amount of water used in was in the range of equation (6). The residual salt mass ratio of the fiber at the time of leaving the washing bath was 0.243. The metal salt concentration in the coagulation bath was adjusted by adding a cleaning solution and water while measuring the density using a density specific gravity meter DA-500 manufactured by Kyoto Electronics Industry Co., Ltd.
Next, when the squeezing roll 7 was passed at 20 m / min, the residual salt mass ratio of the fiber was 0.185. The aqueous solution after washing extracted by the squeezing roll was sent to the circulation tank 10 of the washing bath.

The concentration of the metal salt in the coagulation bath was adjusted by adding fresh washing liquid and water from the washing bath circulation tank 10 while measuring the density using a density specific gravity meter DA-500 manufactured by Kyoto Electronics Industry Co., Ltd. Adjustment was performed so that the metal salt concentration in the tank 4 was constant at 10 wt%.
As the spinning experiment progressed, the coagulating liquid overflowed from the coagulation bath adjustment tank was stored in the overflow tank 5. The coagulating liquid was taken out and heated under reduced pressure at 100 ° C. to concentrate the metal salt concentration to 62 wt%. Using this concentrated solution as a solvent, a polyketone solution was prepared as described above, and spinning was repeated. Although spinning was performed for a total of 200 hours, the pH of the coagulation bath was maintained at about 5 without adjustment, no insoluble matter was generated in the coagulation bath, and yarn breakage in the coagulation bath was observed. There wasn't.

The fiber obtained by the above steps was further washed by spraying 0.5% hydrochloric acid and water on a Nelson roll. The metal salts contained in the subsequent cleaning solutions were recovered by sedimentation with alkali, filtration, etc., and treated as waste. From the mass ratio (7.65) of the metal salt to the polyketone in the polyketone solution and the residual salt mass ratio (0.185) of the fiber after passing through the squeeze roll 7, the discharge rate at which the metal salt is discharged out of the manufacturing process is It was 2.4 wt%.
Further, the washed fiber was dried through a roll dryer at 220 ° C. at a speed of 20 m / min. The first stage of the dried yarn is 7 times at 240 ° C, the second stage is 1.5 times at 255 ° C, the third stage is 1.3 times at 265 ° C, and the fourth stage is 1.2 times at 270 ° C. Four-stage heat stretching was performed.
The fineness of the fiber at this time was 299 dtex, the tensile strength was 17.9 cN / dtex, the elongation was 4.9%, and the tensile modulus was 447 cN / dtex. The tensile strength retention by belt fatigue evaluation was 60%. Even when the coagulation bath was concentrated without being neutralized and reused as a solvent, a polyketone fiber having excellent tensile strength, tensile elastic modulus and fatigue resistance was obtained.

[Comparative Example 1]
The same procedure as in Example was performed except that the pH adjustment of the coagulation bath was set to 4.0. The residual salt mass ratio of the fiber exiting the squeeze roll 7 was 0.203, and the discharge rate at which the metal salt was discharged out of the manufacturing process was 2.6 wt%, which was equivalent to Example 1.
The fineness of the fiber thus obtained was 300 dtex, the tensile strength was 15.9 cN / dtex, the elongation was 4.6%, and the tensile modulus was 354 cN / dtex. As compared with Example 1, only polyketone fibers having a low tensile strength and tensile elastic modulus were obtained. Further, the tensile strength retention by belt fatigue evaluation was 50%, which was slightly lower than that of Example 1.

[Example 2]
The same procedure as in Example 1 was performed except that a Nelson roll was used instead of the squeezing roll 6 after solidification, and a Nelson roll was used instead of the squeezing roll 7 after leaving the washing bath. The mass ratio of the residual salt of the fiber leaving the washing bath was 0.353, and the discharge rate at which the metal salt was discharged out of the manufacturing process was 6.4 wt%.
The fineness of the fiber at this time was 298 dtex, the tensile strength was 18.2 cN / dtex, the elongation was 4.8%, and the tensile modulus was 467 cN / dtex. Further, the tensile strength retention by belt fatigue evaluation was 59%. Even when the coagulation bath was concentrated without being neutralized and reused as a solvent, a polyketone fiber having excellent tensile strength, tensile elastic modulus and fatigue resistance was obtained.

[Example 3]
Pipes having a length of 2 m each having a 1 mm diameter hole in the bottom of the washing bath were arranged in the length direction, and bubbles were generated in the bath by pumping air. The same procedure as in Example 1 was performed except that the washing bath was used. The mass ratio of the residual salt of the fiber exiting the squeezing roll 7 was 0.035, and the discharge rate at which the metal salt was discharged out of the manufacturing process was 0.5 wt%.
At this time, the fineness of the fiber was 300 dtex, the tensile strength was 17.4 cN / dtex, the elongation was 4.9%, and the tensile modulus was 463 cN / dtex. Moreover, the tensile strength retention by belt fatigue evaluation was 60%. Even when the coagulation bath was concentrated without being neutralized and reused as a solvent, a polyketone fiber having excellent tensile strength, tensile elastic modulus and fatigue resistance was obtained.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that hydrochloric acid having a pH of 3 was used instead of the water supplied to the washing bath 8. The metal salt concentration in the coagulation bath was adjusted by adding water because the pH could not be maintained at 5.0 when a washing bath was used. Therefore, all the metal salts extracted in the cleaning process after exiting the squeeze roll 6 were treated as waste. The mass ratio of the residual salt in the coagulated fiber exiting the squeezing roll 6 is 1.29, and the discharge rate at which the metal salt is discharged out of the manufacturing process is 16.9 wt%. It was bad.
The fineness of the obtained fiber was 301 dtex, the tensile strength was 17.5 cN / dtex, the elongation was 4.6%, and the tensile modulus was 454 cN / dtex. Further, the tensile strength retention by belt fatigue evaluation was 58%.
Table 1 summarizes the above results. From this table, it can be seen that according to the production method of the present invention, polyketone fibers having a low metal salt discharge rate and high tensile strength and tensile elastic modulus can be obtained.

  The polyketone fiber obtained by the production method of the present invention has a high tensile strength and a high tensile elastic modulus, and is cheaper. Therefore, the expansion into the fields of rubber reinforcing materials and plastic reinforcing agents is expanded, and particularly fuel efficiency is improved. It is expected to expand to the next generation tire application aiming at.

It is a figure which shows an example of the polyketone manufacturing apparatus by this invention.

Claims (10)

A polyketone in which 95 mol% or more of the repeating unit is represented by the chemical formula (1) is a solvent composed of a 50-80 wt% metal salt aqueous solution and a zinc halide concentration of 10 wt% or more. The step of dissolving the obtained polyketone solution from the spinneret into a coagulation bath satisfying the following conditions (A) to (C), solidifying into a fibrous form, and washing the coagulated fiber with water A part or all of the cleaning liquid is used to adjust the metal salt concentration of the coagulation bath, by extracting a part of the coagulation bath and concentrating it until the metal salt concentration becomes 50 to 80 wt%. A method for producing a polyketone fiber, characterized by being used as a solvent for polyketone.
(A) A metal salt aqueous solution composed of the same metal salt as the solvent.
(B) Metal salt concentration is 1-30 wt%.
(C) The pH is 4.5 to 5.5.

  The method for producing a polyketone fiber according to claim 1, wherein the polyketone solution has a phase separation temperature in a temperature range of 0 to 150 ° C.   The method for producing a polyketone fiber according to claim 1 or 2, wherein the concentration of zinc halide in the solvent is 10 to 30 wt%.   The method for producing a polyketone fiber according to any one of claims 1 to 3, wherein the zinc halide is zinc chloride.   The method for producing a polyketone fiber according to any one of claims 1 to 4, wherein the metal salt of the solvent is a mixture of zinc chloride, calcium chloride and lithium chloride. The amount of water used for washing the coagulated fibers (W, unit: g / min) is in the range shown in Formula (1), and the amount of residual metal salt in the fibers washed with the amount of water is 20 wt% or less. The manufacturing method of the polyketone fiber of any one of Claims 1-5 characterized by the above-mentioned.

(Wherein A is the metal salt concentration (wt%) of the solvent, B is the metal salt concentration (wt%) of the coagulation bath, C is the discharge rate of the spinning dope (g / min), and P is the polymer concentration of the spinning dope ( wt%).)   The metal salt aqueous solution is squeezed from the coagulated fiber by sandwiching the coagulated fiber between two rolls arranged in parallel, and the metal salt aqueous solution is returned to the coagulation bath. The manufacturing method of the polyketone fiber as described in a term.   After washing the coagulated fibers with water, the fibers are sandwiched between two rolls arranged in parallel to squeeze the washing liquid from the fibers, and part or all of the washing liquid is used to adjust the metal salt concentration in the coagulation bath. It uses, The manufacturing method of the polyketone fiber of any one of Claims 1-7 characterized by the above-mentioned.   The method for producing a polyketone fiber according to any one of claims 1 to 8, wherein the coagulated fiber is washed with water by running the fiber in a water bath in which bubbles are generated from below.   A part of the coagulation bath is extracted and concentrated to a metal salt concentration of 50 to 80 wt% using a multi-effect evaporation concentrator, and used as a polyketone solvent. The manufacturing method of the polyketone fiber of Claim 1.

Images