JPH0762284B2 - Method for producing flame-retardant acrylic fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to a flame-retardant acrylic fiber having good light resistance and heat resistance.

(Prior Art) Acrylic fibers have a sublime texture similar to wool, excellent physical properties and dyeability, and are used in a wide range of applications, but interior applications such as carpets and curtains, In a specific application field such as baby clothes, it is strongly required to impart flame retardancy.

Typical examples of flame retardant means are halogens obtained by copolymerizing a halogen-containing vinyl monomer with acrylonitrile (hereinafter referred to as AN) or mixing an AN-based polymer with a flame-retardant polymer such as polyvinyl chloride. Examples thereof include a method of producing a fiber by using a containing AN polymer or a phosphorus containing AN polymer obtained by copolymerizing a phosphorus containing vinyl monomer.

However, the halogen-containing AN polymer has an inherent problem that it induces dehydrohalogenation by light or heat, and a so-called polyene structure is formed by the dehydrohalogenation to cause coloring. Therefore, various stabilizers have been proposed for preventing the halogen-containing polymer from being deteriorated by light or heat.
Main stabilizers such as metal soaps such as lead, cadmium, barium, calcium and zinc, and organic tin compounds, and (b) phosphite compounds (phosphorous acid) which are said to be effective in combination with the main stabilizers Ester), epoxy type, polyol type, β-diketo compound, chelating agent and other stabilizing aids. However, none of these can satisfy both the light resistance, heat resistance and stabilization effect and the operability.

Further, the phosphorus-containing AN polymer is also unstable to light and heat, and particularly when heated in a system in which water is present, it is easily hydrolyzed, and light resistance and heat resistance are significantly deteriorated. There is no practical way to do it.

(Problems to be Solved by the Invention) An object of the present invention is to provide good light resistance and heat resistance without troubles such as clogging in the over-process in the fiber manufacturing process, pressure troubles, nozzle clogging in the spinning process, yarn breakage, etc. It is to provide a method for producing a flame-retardant acrylic fiber.

(Means for Solving Problems) The above-mentioned object of the present invention is to provide a solution of a phosphorus-containing acrylonitrile-based polymer in an inorganic salt solvent, in which a salt of aluminum or zinc soluble in the solvent is added to the weight of the polymer. In contrast, 0.01 to 3.0% of the weight of aluminum or zinc is blended and the pH of the solution is adjusted to 6.0 or less by wet spinning a polymer stock solution, the hydroxide of the metal having a particle size of 0.4μ or less It is achieved by a method for producing a flame-retardant acrylic fiber, which is characterized in that:

Hereinafter, the present invention will be described in detail.

First, as the phosphorus-containing AN-based polymer, one type of polymer or a mixture of two or more types of polymers containing AN and a phosphorus-containing vinyl monomer as an essential copolymerization component, and a mixture of the AN-based polymer and phosphorus. Examples include a mixture with a polymer containing a vinyl monomer containing 40 to 98% by weight of AN in the polymer, preferably 60 to 90%, and a vinyl monomer containing phosphorus of 2 to 2 in each case.
Within the range of 30%, preferably 3 to 20%, halogen-containing vinyl monomer is 0 to 30%, preferably 5 to 25%, and other vinyl monomer is 0 to 40%, preferably 0 to 20%. It is desirable that the material contains a bond.

Here, as the phosphorus-containing vinyl monomer, bis (2-chloroethyl) vinylphosphonate, bis (2-bromoethyl) vinylphosphonate, bis (2-chloroethyl)
Methallyl phosphonate, bis (2-bromoethyl) methallyl phosphonate, diethyl allyl phosphonate, N-
Unsaturated phosphonates such as phosphonomethyl acrylamide; unsaturated hydroxyphosphates such as 2-hydroxyethyl methacrylate acid phosphate, diphenyl 2-methacryloyloxyethyl phosphate, and dibutyl 2-methacryloyloxyethyl phosphate.

Examples of the halogen-containing vinyl monomer include vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, and other vinyl halides and vinylidene halides. , Esters of (meth) acrylic acid such as methyl, ethyl, butyl, octyl, methoxyethyl, phenyl and cyclohexyl;
Vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate; acrylamide and its alkyl-substituted compounds; unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, itaconic acid and salts thereof; vinyl sulfonic acid, (meth ) Unsaturated sulfonic acids such as allylsulfonic acid, P-styrenesulfonic acid, acrylamidopropanesulfonic acid, and salts thereof; styrene, methyl vinyl ketone, methyl vinyl ether, allyl alcohol, vinylipyridine, dimethylaminoethyl methacrylate, vinylidene cyanide, methacrylic acid. Examples thereof include vinyl compounds such as ronitrile and glycidyl methacrylate. In addition,
As a method for producing these polymers, known methods such as emulsion polymerization, aqueous precipitation polymerization, aqueous suspension polymerization, solution polymerization and the like can be adopted.

Next, as a means for forming a hydroxide of aluminum or zinc having a particle size of 0.4 μ or less, preferably 0.1 μ or less in the fiber, the above-mentioned hydroxide having a predetermined particle size is industrially difficult to obtain, and also obtainable. Even if the particles are mixed, the particles agglomerate at the time of mixing in the spinning solution (polymer solution), causing problems such as clogging and pressurization trouble in the over process, nozzle clogging and yarn breakage in the spinning process, and finally the purpose. The following means are recommended because the fiber to be obtained cannot be obtained.

That is, an inorganic salt solvent solution of a phosphorus-containing AN polymer is blended with a salt of aluminum or zinc soluble in the solvent to prepare a spinning dope, and the spinning dope is spun according to a conventional method, and post-treated. The means to do is adopted. The aluminum or zinc salt can be used as long as it can be dissolved in the solvent,
Examples thereof include aluminum or zinc nitrate, sulfate, hydrochloride, acetate and the like. Further, as the inorganic salt-based solvent, a concentrated aqueous solution of rhodanic salt such as known as AN-based polymer solvent, rodan soda, rodan ammon, rodan ammonium, rodan calcium; concentrated aqueous chloride solution such as zinc chloride and calcium chloride, Further, it is possible to use a mixed solvent obtained by mixing a known organic solvent for AN polymer such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, ethylene carbonate, γ-butyrolactone, and acetone to these solvents within a range that does not impair the dissolving ability. Is.

The amount of the salt blended is 0.05 to 20%, preferably 0.2 to 5.0% (0.01 to 3%, preferably 0.05 to 0.05% by weight of aluminum or zinc) based on the weight of the polymer.
It is desirable to set the content within the range of 1.0% to 1.0%), and when it deviates from the lower limit of this range, there is no effect of imparting light resistance to heat stability and flame retardancy. This is not desirable because it not only results in deterioration of the physical properties of the finally obtained fiber.

In addition, as a method for compounding the salt, a means for adding and mixing a predetermined amount of the salt in the form of a granule or an aqueous solution to an inorganic salt solvent solution of a phosphorus-containing AN polymer may be mentioned. it can.
It should be noted that if the pH of the solution is high, the salt will not dissolve, so it is desirable to adjust the pH of the solution to 6.0 or less, preferably 4.0 or less. Further, when heating is required when the polymer is dissolved, the phosphorus-containing AN polymer is already deteriorated in such a step, so it is desirable to add and mix the salt in a so-called slurry state before heating and dissolution. .

Thus, the phosphorus-containing AN polymer solution (spinning stock solution) in which the salt of aluminum or zinc is blended is subjected to spinning, coagulation, washing, washing with water and / or stretching after water washing, wet heat stretching, and drying according to a conventional method. After each step such as the above, the aluminum or zinc hydroxide having a particle diameter of 0.4 μm or less, preferably 0.1 μm or less is contained without any problems in the manufacturing process, and the fiber is formed into a fiber having excellent performance.

(Function) The reason why the fiber according to the present invention has excellent stability against light and heat resistance has not been sufficiently clarified, but it is presumed as follows.

That is, the phosphorus-containing vinyl monomer is unstable to light and heat, and particularly in the presence of water, the bond is broken (hydrolyzed) at the dotted line portion, as shown schematically below. -OH
(Acid type) is generated, which deteriorates light resistance and heat resistance, while it captures an acidic substance in which aluminum or zinc present uniformly and finely in the fiber is liberated and is coordinated with the generated -P-OH. It is thought that it stabilizes.

Further, when the fibrous polymer contains halogen, hydrogen halide desorbed by light or heat or a reaction product of the hydrogen halide and a metal such as iron, nickel or cobalt is used as a catalyst. Since it works to promote dehydrohalogenation, a polyene structure is formed in the polymer and coloring proceeds, while aluminum or zinc present in the fiber uniformly and finely captures the hydrogen halide. It is considered that the metal halide formed therewith has no catalytic action, and thus effectively suppresses the progress of the dehydrohalogenation reaction.

The aluminum or zinc salt recommended in the present invention is
It is uniformly dissolved and mixed (containing at the molecular level) with the polymer in the spinning dope, which may cause problems such as clogging and pressure rise problems in the over process, nozzle clogging and yarn breakage in the spinning process. In addition, in the process of coagulation, washing with water, stretching, etc.
Forming gradually water-insoluble metal hydroxide by increasing pH,
Finally, it seems that the fibers can be uniformly and finely present.

(Effect of the Invention) As described above, the fact that the fibrous acrylic fiber having good light resistance and heat resistance can be provided without any problems in the manufacturing process is a remarkable industrial advantage of the present invention.

Further, since the fine particles of aluminum or zinc hydroxide are uniformly present in the fiber of the present invention, there is no problem in the transparency of the fiber, dyeing sharpness, etc., and the commercial value is not lost at all. Flame retardancy is imparted, and such a point is also an effect of the present invention.

(Examples) Examples are shown below to facilitate understanding of the present invention.
These are merely examples, and the gist of the present invention is not limited by these. The parts and percentages shown in the examples are by weight unless otherwise specified. The light resistance, heat resistance, and particle size of aluminum or zinc hydroxide present in the fiber were measured and evaluated as follows.

(1) Light resistance Lightfastness measurement conditions Measuring device: Suga Test Instruments Co., Ltd. UV long life
Fade meter FAL-3H machine Black panel temperature: 63 ± 3 ℃ Exposure time: 40 hours Judgment method Gray scale (JI
It is indicated by the grade of SL-0804). The larger the grade, the better the light resistance.

(2) Heat resistance Heat resistance measurement conditions Measuring device: Hot air dryer manufactured by Tabai Co., Ltd. Temperature x time: 150 ° C x 10 minutes Judgment method Gray scale (JI
It is indicated by the grade of SL-0804). The higher the grade, the better the heat resistance.

(3) Particle size Using a transmission electron microscope (TBM) manufactured by Hitachi Ltd., the fiber cross section was examined under a microscope (magnification: 150,000 times) to determine the average particle size of the metal hydroxide.

Example 1 Using a redox catalyst, a conventional aqueous precipitation polymerization method was used.
A polymer (A) consisting of 84 parts and 16 parts of bis (2-chloroethyl) vinylphosphonate (CEVP) was prepared.

Next, when preparing a solution of the polymer (A) having a polymer concentration of 12% and rhodanesoda 40% using a concentrated aqueous solution of rhodanesa, first, a predetermined amount of the polymer and a solvent are mixed, and aluminum nitrate is dissolved before heating and dissolving. For polymer
After 0.2% (aluminum equivalent) was added and the pH was adjusted to 3.8, it was dissolved at 70 ° C. for 1 hour using an ordinary stirrer to prepare a spinning dope.

The obtained stock solution was spun in a 13% aqueous solution of rhodanesa at a temperature of -3 ° C, washed with water, stretched, dried, and heat-treated in a conventional manner to prepare 10 ^d of fiber (1). The obtained fiber (1) had a LOI value of 22 for nits. Further, as a comparative example, a fiber (2) was produced in the same manner as above except that aluminum nitrate was added after the polymer was heated and dissolved, and a fiber (3) was produced in the same manner as above except that aluminum nitrate was not added.

The results of evaluating the light resistance and heat resistance of the fibers (1 to 3) are
It is shown in Table 1.

From the above, it can be clearly understood that the product of the present invention has excellent flame retardancy and the light resistance and heat resistance are significantly improved.

Example 2 Example 1 except that the addition amount of aluminum nitrate (aluminum equivalent) and the pH of the spinning dope were changed as shown in Table 2 below.
Six kinds of fibers (4 to 9) were produced in the same manner as the fiber (1).

The results of evaluation of light resistance and heat resistance are also shown in Table 2.

From the above table, the amount of stabilizer added and the stock solution pH recommended in the present invention
It is understood that within the range, the light resistance and heat resistance improving effect is particularly remarkable.

Example 3 Eight kinds of fibers (10 to 17) were prepared in the same manner as the fiber (1) of Example 1 except that the kind of the stabilizer and the pH of the stock solution were changed as shown in Table 3 below.

The results of evaluation of light resistance and heat resistance are also shown in Table 3.

From the above, it is understood that the product of the present invention has an excellent light resistance and heat resistance improving effect.

Example 4 A polymer (B) consisting of 72 parts of AN, 6 parts of methyl acrylate, 8 parts of CEVP, 14 parts of vinylidene chloride and 0.3 part of sodium methallyl sulfonate was prepared in the same manner as in Example 1, and the polymer concentration was 10%. A fiber (18) was produced in the same manner as the fiber (1) of Example 1 except that a solution of 45% rodan soda was used.

The fiber (18) had a Nit LOI value of 23, and the fiber had good light resistance of grade 4 to 5 and heat resistance of grade 3 to 4.

Claims (1)

[Claims] 1. A solution of a phosphorus-containing acrylonitrile-based polymer in an inorganic salt-based solvent, wherein the salt of aluminum or zinc soluble in the solvent is 0.01 to 3.0 based on the weight of aluminum or zinc based on the weight of the polymer. % And pH of the solution
Is wet-spun polymer undiluted solution adjusted to 6.0 or less,
A method for producing a flame-retardant acrylic fiber, which comprises forming a hydroxide of the metal having a particle size of 0.4 μ or less.