CN107250449B

CN107250449B - Method for producing acrylic fiber

Info

Publication number: CN107250449B
Application number: CN201680010507.2A
Authority: CN
Inventors: 吉村悟; 穴原贤
Original assignee: Kaneka Corp
Current assignee: Kaneka Corp
Priority date: 2015-02-16
Filing date: 2016-02-01
Publication date: 2020-09-15
Anticipated expiration: 2036-02-01
Also published as: CN107250449A; WO2016132877A1; TW201638408A; US20170335491A1

Abstract

The present invention relates to a method for producing an acrylic fiber, wherein a spinning dope obtained by dissolving an acrylic copolymer in an organic solvent is wet-spun to obtain an acrylic fiber, wherein the acrylic copolymer comprises 20 to 85 mass% of acrylonitrile, 14.5 to 79.5 mass% of vinyl chloride, and 0.5 to 10 mass% of a monomer containing a sulfonic acid group, relative to the entire mass of the acrylic copolymer, the organic solvent is dimethyl sulfoxide, and the spinning dope comprises water and a condensed phosphate.

Description

Method for producing acrylic fiber

Technical Field

The present invention relates to a method for producing an acrylic fiber by wet spinning a spinning dope obtained by dissolving an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride, and a monomer having a sulfonic acid group in dimethyl sulfoxide.

Background

Acrylic fibers, particularly acrylic fibers made of an acrylic copolymer containing vinyl chloride or vinylidene chloride as one of the copolymerization components, are preferably used as fibers for artificial hair for wigs, wig pieces, weaving processes and the like because they have a soft touch. In general, acrylic fibers used as artificial hair are produced by wet spinning using a spinning dope obtained by dissolving an acrylic copolymer in a good solvent such as dimethyl sulfoxide. For example, patent document 1 describes: an acrylic fiber obtained from an acrylic copolymer made from acrylonitrile, vinylidene chloride, and a sulfonic acid group-containing vinyl monomer is produced by a wet spinning method using a good solvent.

However, patent document 1 uses vinylidene chloride as a copolymerization component with acrylonitrile, but has a problem of poor curl setting properties by hot water. Therefore, in order to improve the curl setting property by hot water, vinyl chloride is used as a copolymerization component with acrylonitrile.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2002-315765

Disclosure of Invention

Problems to be solved by the invention

However, the present inventors have found that when acrylic fibers are produced by wet spinning a spinning dope obtained by dissolving an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride and a sulfonic acid group-containing monomer in dimethyl sulfoxide using highly safe dimethyl sulfoxide as a good solvent, the acrylic fibers are colored yellow or brown.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing an acrylic fiber, in which even when a spinning dope obtained by dissolving an acrylic copolymer containing vinyl chloride as a copolymerization component in dimethyl sulfoxide is wet-spun, the coloration of the obtained acrylic fiber can be suppressed.

Means for solving the problems

The present invention relates to a method for producing an acrylic fiber, which is characterized by wet-spinning a spinning dope obtained by dissolving an acrylic copolymer in an organic solvent, wherein the acrylic copolymer comprises 20 to 85 mass% of acrylonitrile, 14.5 to 79.5 mass% of vinyl chloride, and 0.5 to 10 mass% of a monomer containing a sulfonic acid group, relative to the total mass of the acrylic copolymer, the organic solvent is dimethyl sulfoxide, and the spinning dope comprises water and a condensed phosphate.

The spinning dope preferably contains 0.05 to 5 mass% of a condensed phosphate based on the entire mass of the acrylic copolymer.

The condensed phosphate is preferably at least one compound selected from the group consisting of pyrophosphate, tripolyphosphate, tetrapolyphosphate, trimetaphosphate and tetrametaphosphate, and is more preferably tripolyphosphate.

Effects of the invention

According to the present invention, the following acrylic fiber can be provided: even when a spinning dope obtained by dissolving an acrylic copolymer containing vinyl chloride as a copolymerization component in dimethyl sulfoxide is wet-spun, the coloring is suppressed from being yellow or brown.

Detailed Description

The present inventors have conducted intensive studies to solve the problem that acrylic fibers are colored yellow or brown when a spinning dope obtained by dissolving an acrylic copolymer containing acrylonitrile, vinyl chloride, and a monomer having a sulfonic acid group in dimethyl sulfoxide (DMSO) is wet-spun, and as a result, have found that: the present inventors have completed the present invention by adding water and a condensed phosphate to a spinning dope, thereby making it possible to obtain a good spinnability and to suppress coloring of an acrylic fiber into yellow or brown. It is presumed that when a spinning dope obtained by dissolving an acrylic copolymer in dimethyl sulfoxide is wet-spun, a dehydrochlorination reaction of the acrylic copolymer occurs in the production process, and the produced hydrochloric acid decomposes the dimethyl sulfoxide to color the fiber in yellow or brown. When the step of dissolving the acrylic copolymer in dimethyl sulfoxide is performed at a temperature higher than room temperature for a long time, the dehydrochlorination reaction of the acrylic copolymer becomes more remarkable. Condensed phosphates are commonly used as phosphorus-based flame retardants to improve the flame retardancy of fibers, but surprisingly, in the present invention: by adding a condensed phosphate to a spinning dope obtained by dissolving an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride, and a monomer having a sulfonic acid group in dimethyl sulfoxide, and then performing wet spinning, the coloring of acrylic fibers into yellow or brown can be suppressed. The mechanism of inhibiting coloring of acrylic fibers by adding a condensed phosphate to a spinning dope together with water and then performing wet spinning is not clear, but it is presumed that the mechanism is due to: hydrochloric acid (hydrogen ion) generated by the dehydrochlorination reaction of the acrylic copolymer is used for the equilibrium reaction with the phosphate group derived from the condensed phosphate dissolved in water, and the decomposition of DMSO generated from hydrochloric acid can be prevented.

The acrylic copolymer contains 20 to 85 mass% of acrylonitrile, 14.5 to 79.5 mass% of vinyl chloride and 0.5 to 10 mass% of a sulfonic acid group-containing monomer with respect to the entire mass of the acrylic copolymer. When the content of vinyl chloride in the acrylic copolymer is 14.5 to 79.5 mass%, the flame retardancy is improved. When the content of acrylonitrile in the acrylic copolymer is 20 to 85 mass%, the heat resistance is good, and the processing temperature at the time of curl setting can be appropriately set. The acrylic copolymer contains 0.5 to 10 mass% of a sulfonic acid group-containing monomer, and thus has increased hydrophilicity and reduced porosity. The acrylic copolymer preferably contains 20 to 80 mass% of acrylonitrile, 19.5 to 79.5 mass% of vinyl chloride, and 0.5 to 5 mass% of a monomer containing a sulfonic acid group, and more preferably contains 20 to 75 mass% of acrylonitrile, 24.5 to 79.5 mass% of vinyl chloride, and 0.5 to 5 mass% of a monomer containing a sulfonic acid group.

The sulfonic acid group-containing monomer is not particularly limited, and examples thereof include metal salts such as allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, isoprene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and sodium salts thereof, and amine salts. The sulfonic acid group-containing monomers may be used alone or in combination of 2 or more.

The acrylic copolymer was dissolved in dimethyl sulfoxide. By using dimethyl sulfoxide as an organic solvent, safety is improved.

From the viewpoint of effectively suppressing coloring of the acrylic fiber, the spinning dope preferably contains a condensed phosphate in an amount of 0.05 mass% or more, more preferably 0.06 mass% or more, and still more preferably 0.07 mass% or more, relative to the entire mass of the acrylic copolymer. The upper limit of the condensed phosphate is, from the viewpoint of coloration prevention and spinning property, preferably 5 mass% or less, more preferably 4.5 mass% or less, still more preferably 4 mass% or less, still more preferably 3.5 mass% or less, yet more preferably 3 mass% or less, yet more preferably 2.5 mass% or less, yet more preferably 2 mass% or less, yet more preferably 1.5 mass% or less, yet more preferably 1 mass% or less, yet more preferably 0.9 mass% or less, yet more preferably 0.7 mass% or less, yet more preferably 0.5 mass% or less of the condensed phosphate.

The condensed phosphate is not particularly limited as long as it is an inorganic condensed phosphate. For example, pyrophosphate, tripolyphosphate, tetrapolyphosphate, trimetaphosphate, tetrametaphosphate, and the like can be used. Among them, from the viewpoint of ease of obtaining and high solubility, tripolyphosphate is preferable. The type of the salt is not particularly limited, and may be any of sodium salt, potassium salt, ammonium salt, and the like. From the viewpoint of excellent solubility in water, the salt is preferably a water-soluble salt such as a sodium salt or a potassium salt. Examples of the pyrophosphate (also referred to as a diphosphate) include sodium pyrophosphate, potassium pyrophosphate, and the like. Examples of the tripolyphosphate include sodium tripolyphosphate, ammonium dihydrogen tripolyphosphate, and potassium tripolyphosphate. Examples of tetrapolyphosphate include sodium tetrapolyphosphate and potassium tetrapolyphosphate.

From the viewpoint of solubility and spinnability of the condensed phosphate, the spinning dope preferably contains 8 to 16 mass% of water, more preferably 8 to 15 mass% of water, further preferably 8 to 14 mass% of water, further preferably 8 to 13 mass% of water, and further preferably 8 to 12.5 mass% of water, based on the entire mass of the acrylic copolymer.

The dope is different depending on the composition of the acrylic copolymer, but for example, it preferably contains 20 to 30 mass% of the acrylic copolymer, 65.2 to 78.49 mass% of DMSO, 1.5 to 4.8 mass% of water, and 0.01 to 1.5 mass% of a condensed phosphate, more preferably 22 to 30 mass% of the acrylic copolymer, 66 to 75.99 mass% of DMSO, 2 to 4 mass% of water, and 0.01 to 1.5 mass% of a condensed phosphate, and further preferably contains 25 to 30 mass% of the acrylic copolymer, 66.5 to 72.49 mass% of DMSO, 2.5 to 3.5 mass% of water, and 0.01 to 1.5 mass% of a condensed phosphate, based on the entire mass of the dope.

The dope may contain other additives for improving the fiber characteristics as needed, as long as the effects of the present invention are not hindered. Examples of the additives include titanium dioxide, silica, gloss control agents such as esters and ethers of cellulose derivatives mainly composed of cellulose acetate, coloring agents such as organic pigments, inorganic pigments and dyes, and stabilizers for improving light resistance and heat resistance.

The spinning dope is not particularly limited, and can be prepared by mixing an acrylic copolymer, DMSO, water, and a condensed phosphate. From the viewpoint of solubility of the condensed phosphate, the spinning dope is preferably prepared by mixing an acrylic copolymer, DMSO, and an aqueous solution of the condensed phosphate. In order to improve the solubility of the acrylic copolymer, it is preferable to prepare a spinning dope by adding an aqueous solution of DMSO and a condensed phosphate to the acrylic copolymer and then stirring the resulting mixture at 40 to 80 ℃ for 3 to 12 hours, more preferably at 50 to 75 ℃ for 4 to 10 hours, and still more preferably at 60 to 70 ℃ for 5 to 8 hours. Further, it is presumed that if a mixture of an acrylic copolymer, DMSO, and an aqueous solution of a condensed phosphate is treated at 60 ℃ or higher for 5 hours or longer, for example, in the preparation of a spinning dope, hydrochloric acid can be generated by the dehydrochlorination reaction of the acrylic copolymer, but the decomposition of DMSO generated by hydrochloric acid can be prevented by utilizing hydrochloric acid (hydrogen ion) in the equilibrium reaction with a phosphate group derived from the condensed phosphate, and the coloration of the fiber into yellow or brown can be suppressed. As the acrylic copolymer, an acrylic copolymer containing moisture can be used. When an acrylic copolymer containing moisture (hereinafter also simply referred to as a water-containing acrylic copolymer) is used as the acrylic copolymer, the total mass of the acrylic copolymer in the present invention means the dry mass of the acrylic copolymer, and the mass of the water-containing acrylic copolymer after drying at 60 ℃ for 10 hours and removing moisture is measured as the dry mass of the acrylic polymer. As DMSO, DMSO containing water may be used. In the present specification, unless otherwise specified, an acrylic copolymer means an acrylic copolymer containing no moisture, and DMSO means DMSO containing no moisture.

The acrylic fiber is obtained by wet spinning the spinning dope by a usual method. For example, the spinning dope is first discharged through a spinning nozzle or directly into a coagulation liquid (coagulation bath) made of a DMSO aqueous solution, and coagulated to form fibers. For example, a DMSO aqueous solution having a DMSO concentration of 40 to 70 mass% is used as the coagulation bath, and the temperature can be set to 5 to 40 ℃. When the concentration of a good solvent such as DMSO in the coagulation bath is too low, the following tendency is exhibited: the solidification is accelerated, the solidification structure becomes thick, and pores are formed inside the fibers.

Next, the fiber (coagulated yarn) is taken out into a DMSO aqueous solution having a DMSO concentration lower than that of the coagulation solution by 30 ℃ or higher or hot water having a DMSO concentration of 30 ℃ or higher, desolventized, washed with water, and stretched, and if necessary, the fiber may be relaxed after stretching. Preferably, the stretching is performed in a DMSO aqueous solution having a DMSO concentration of 30 ℃ or higher than that of the coagulation solution, and then the stretching is washed with hot water having a DMSO concentration of 30 ℃ or higher. The solvent was removed by water washing. The draw ratio is not particularly limited, but is preferably 2 to 8 times, more preferably 2 to 7 times, and still more preferably 2 to 6 times, from the viewpoint of enhancing the strength and productivity of the fiber. It is presumed that hydrochloric acid can be generated by the dehydrochlorination reaction of the acrylic copolymer if the fiber is treated at 80 ℃ or higher for 1 hour or more in the desolvation, washing with water, and drawing in an aqueous DMSO solution, for example, but the generated hydrochloric acid (hydrogen ion) is utilized in an equilibrium reaction with a phosphate group derived from a condensed phosphate, whereby the decomposition of DMSO generated by the hydrochloric acid can be prevented, and the coloring of the fiber into yellow or brown can be suppressed.

The fibers (drawn filaments) may then be dried. During drying, an oil agent may be attached as needed. The finish may be any finish generally used for the purpose of preventing static electricity, preventing adhesion of fibers, and improving the texture in the spinning step, and known finishes may be used. The drying temperature is not particularly limited, and is, for example, 110 to 190 ℃, preferably 110 to 160 ℃. The dried fiber may be further stretched as necessary, and the stretching ratio thereof is preferably 1 to 4 times. The total stretching ratio including stretching before drying is preferably 2 to 12 times.

The fiber obtained by drying or further drawing after drying is preferably subjected to a relaxation treatment of 15% or more. The relaxation treatment may be carried out at a high temperature, for example, 150 to 200 ℃, preferably 150 to 190 ℃ under a dry heat or superheated steam atmosphere. Alternatively, the reaction can be carried out in an atmosphere of pressurized steam or heated pressurized steam at 120 to 180 ℃ and 0.05 to 0.4MPa, preferably 0.1 to 0.4 MPa.

The acrylic fiber preferably has a single fiber fineness of 30 to 100dtex, more preferably 40 to 80dtex, and further preferably 45 to 70dtex, from the viewpoint of being suitably used as artificial hair. Here, the single fiber fineness is an average value of fineness of 100 arbitrary single fibers.

The acrylic fiber may contain phosphorus derived from condensed phosphate. For example, the acrylic fiber may contain 5 to 250ppm of phosphorus, 10 to 150ppm of phosphorus, or 15 to 80ppm of phosphorus based on the entire mass of the acrylic fiber. The phosphorus can be quantified as described later.

Examples

The present invention will be described more specifically with reference to examples. Further, the present invention is not limited to the following examples.

(example 1)

< spinning dope >

500g of an acrylic copolymer comprising 45.7 mass% of acrylonitrile, 52.3 mass% of vinyl chloride and 2.0 mass% of sodium styrenesulfonate, 62.5g of an aqueous solution of DMSO1223g and 0.61 mass% of sodium tripolyphosphate were put into a 7L stainless steel container, and the mixture was stirred at 70 ℃ for 12 hours to dissolve the acrylic copolymer, thereby preparing a spinning dope.

< spinning conditions >

The obtained spinning dope was wet-spun at a spinning speed of 2 m/min in a coagulation bath of a 57 mass% DMSO aqueous solution at 20 ℃ using a spinning nozzle (pore diameter: 0.3mm, number of pores: 50), and then drawn 3-fold in a drawing bath of a 50 mass% DMSO aqueous solution at 80 ℃. Subsequently, the resultant was washed with water at 90 ℃ in hot water, dried at 140 ℃, stretched 2-fold, and subjected to 20% relaxation treatment at 160 ℃ to obtain an acrylic fiber having a single fiber fineness of about 46 dtex.

(example 2)

An acrylic fiber having a single fiber fineness of about 46dtex was obtained in the same manner as in example 1, except that an aqueous solution of sodium tripolyphosphate having a concentration of 1.22 mass% was used instead of the aqueous solution of sodium tripolyphosphate having a concentration of 0.61 mass%.

(example 3)

An acrylic fiber having a single fiber fineness of about 46dtex was obtained in the same manner as in example 1, except that an aqueous solution of sodium tripolyphosphate having a concentration of 2.44 mass% was used instead of the aqueous solution of sodium tripolyphosphate having a concentration of 0.61 mass%.

(example 4)

An acrylic fiber having a single fiber fineness of about 46dtex was obtained in the same manner as in example 1, except that an aqueous solution of sodium tripolyphosphate having a concentration of 3.66 mass% was used instead of the aqueous solution of sodium tripolyphosphate having a concentration of 0.61 mass%.

(example 5)

An acrylic fiber having a single fiber fineness of about 46dtex was obtained in the same manner as in example 1, except that an aqueous solution of sodium pyrophosphate at a concentration of 1.22 mass% was used instead of an aqueous solution of sodium tripolyphosphate at a concentration of 0.61 mass%.

(example 6)

An acrylic fiber having a single fiber fineness of about 46dtex was obtained in the same manner as in example 1, except that an aqueous solution of sodium tetrapolyphosphate having a concentration of 1.22 mass% was used instead of an aqueous solution of sodium tripolyphosphate having a concentration of 0.61 mass%.

Comparative example 1

An acrylic fiber having a single fiber fineness of about 46dtex was obtained in the same manner as in example 1, except that pure water was used instead of the aqueous solution of sodium tripolyphosphate at a concentration of 0.61 mass%.

Comparative example 2

< spinning dope >

500g of an acrylic copolymer comprising 45.7 mass% of acrylonitrile, 52.3 mass% of vinyl chloride and 2.0 mass% of sodium styrenesulfonate, 500g of DMSO1223g and 0.7625g of sodium tripolyphosphate were placed in a 7L stainless steel container, and the mixture was stirred at 70 ℃ for 12 hours to dissolve the acrylic copolymer, thereby preparing a spinning dope.

< spinning conditions >

The obtained spinning dope was wet-spun at a spinning speed of 2 m/min in a coagulation bath of a 57 mass% DMSO aqueous solution at 20 ℃ using a spinning nozzle (pore diameter: 0.3mm, number of pores: 50), and then drawn 3-fold in a drawing bath of a 50 mass% DMSO aqueous solution at 80 ℃. Subsequently, the fiber was washed with hot water at 90 ℃ and dried at 140 ℃ and then stretched 2-fold, and subjected to 20% relaxation treatment at 160 ℃ to obtain an acrylic fiber having a single fiber fineness of about 46 dtex. After 2 hours from the start of spinning, 50 broken filaments were observed in the coagulation bath, and the operability was extremely unstable.

The color of the acrylic fibers of examples 1 to 6 and comparative examples 1 to 2 was measured by the following colorimetric method, and the results are shown in table 1 below. The content of phosphorus in the acrylic fibers of examples 1 to 6 and comparative examples 1 to 2 was measured by the following method for determining phosphorus, and the results are shown in table 1 below. Table 1 below also shows the amount of condensed phosphate and the amount of water blended with respect to the entire mass of the acrylic copolymer in the spinning dope.

(method of measuring color of fiber)

A color measurement sample was prepared so that 500 fibers had a width of 5mm, and color measurement was performed at any 4 positions under the conditions of 10 ° for diffused illumination, D65 for light reception, 8mm for measurement diameter, and SCE using a spectrocolorimeter ("CM-2600D" manufactured by Konic Minolta corporation), and the average value of the measurement values was determined as hue.

(method of quantifying phosphorus)

Sulfuric acid, nitric acid, hydrofluoric acid, and perchloric acid were added to the fibers cut so that the cut length reached 0.5cm, and thermal decomposition was performed at 120 ℃ under reflux conditions. Heating and concentrating until sulfuric acid white smoke is generated, and heating and dissolving for 45 minutes at 100 ℃ by using dilute nitric acid to perform constant volume. The obtained constant volume solution was used to quantify the phosphorus element by an ICP emission spectrometer ("SPS 4000" manufactured by the fine electronic industry).

TABLE 1

From the results in table 1, it is understood that in the wet spinning using the spinning dope obtained by dissolving the acrylic copolymer containing acrylonitrile, vinyl chloride and the monomer having a sulfonic acid group in dimethyl sulfoxide, the values of a and b, particularly the value of b, are lower by 0.5 or more and the coloring of the acrylic fiber is reduced in the examples 1 to 6 in which the spinning dope contains water and condensed phosphate, compared to the comparative example 1 in which the condensed phosphate is not added to the spinning dope. In addition, in comparative example 2 in which a condensed phosphate was added to the dope but no water was added, yarn breakage occurred as described above, and spinning property was poor.

Claims

1. A process for producing an acrylic fiber, which comprises wet-spinning a dope obtained by dissolving an acrylic copolymer in an organic solvent,

the acrylic copolymer comprises 20 to 85 mass% of acrylonitrile, 14.5 to 79.5 mass% of vinyl chloride and 0.5 to 10 mass% of a sulfonic acid group-containing monomer based on the entire mass of the acrylic copolymer,

the organic solvent is dimethyl sulfoxide, and the organic solvent is dimethyl sulfoxide,

the spinning dope comprises water and a water-soluble condensed phosphate,

the spinning dope contains 0.05 to 5 mass% of a water-soluble condensed phosphate with respect to the entire mass of the acrylic copolymer,

the acrylic fiber contains 5 to 57ppm of phosphorus derived from the water-soluble condensed phosphate,

the water-soluble condensed phosphate is at least one compound selected from pyrophosphate, tripolyphosphate, tetrapolyphosphate, trimetaphosphate and tetrametaphosphate.

2. The method for producing an acrylic fiber according to claim 1, wherein the dope comprises 20 to 30 mass% of the acrylic copolymer, 65.2 to 78.49 mass% of the dimethyl sulfoxide, 1.5 to 4.8 mass% of the water, and 0.01 to 1.5 mass% of the water-soluble condensed phosphate, based on the entire mass of the dope.

3. The method for producing acrylic fibers according to claim 1, wherein the water-soluble condensed phosphate is a tripolyphosphate.