JPS61266611A - Flame-retardant acrylic fiber having excellent abrasion resistance and color developability and production thereof - Google Patents

Abstract

PURPOSE:To obtain the titled acrylic fiber having excellent abrasion resistance and developing deep color, from a flame-retardant copolymerized acrylic polymer obtained by the copolymerization of acrylonitrile, vinylidene chloride, and a sulfonic acid group-containing hydrophilic olefin monomer. CONSTITUTION:A flame-retardant acrylic polymer is produced by copolymerizing (A) 50-85wt% acrylonitrile and a monomer copolymerizable with acrylonitrile, (B) 15-50wt% vinylidene chloride and (C) 0.4-3wt% hydrophilic olefin monomer having sulfonic acid, group. the obtained acrylic polymer is spun by wet spinning process into a coagulation bath having a concentration higher than critical concentration at a spinning draft of >=5 in coagulation, and the spun fiber is drawn at a draw ratio of >=4 in a drawing bath maintained to 20-70 deg.C and having a concentration falling within +0.5% and +9% from the concentration of the coagulation bath. The objective flame-retardant acrylic fiber having excellent abrasion resistance and capable of developing deep color can be produced by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flame retardant acrylic fiber having excellent abrasion resistance and deep coloring, and a method for producing the same.

Conventional technology Traditionally, flame-retardant acrylic fibers have been used in public facilities such as hotels and hospitals, as well as car ferries, by taking advantage of their flame-retardant properties.

Demand is increasing year by year for interior bedding, such as curtains, carpets, and blankets used in sleeping cars, and clothing for the elderly and babies.

In particular, with the recent advancement in interior design, there is an extremely high demand for flame-retardant acrylic fibers that have excellent abrasion resistance and deep color development.

Problems to be Solved by the Invention The present inventor has conducted extensive research into improving the abrasion resistance and coloring properties of such flame-retardant acrylic fibers, and has arrived at the present invention.

Means for Solving the Problems The present invention provides 50-85% by weight of acrylonitrile and other monomers copolymerizable with acrylonitrile;
It is composed of a flame-retardant acrylic polymer consisting of vinylidene chloride with a weight of 0% by weight and a hydrophilic olefinic monomer containing sulfonic acid groups with a weight of 0.4 to 3 times. A flame-retardant acrylic fiber with excellent abrasion resistance and color development that has the following abrasion resistance and deep color development of grade 3.5 or higher, and can be copolymerized with 50 to 85% by weight of acrylonitrile and acrylonitrile. and other monomers such as
When wet-spinning a flame-retardant acrylic polymer made of a hydrophilic olefinic monomer having an amount of 11 L of sulfonic acid groups, it is spun into a coagulation bath with a critical concentration of 5 or more, and the spinning draft at the time of coagulation is 5 or more. +0 from the coagulation bath concentration
．． A method for producing a flame-retardant acrylic fiber with excellent abrasion resistance and color development, characterized by stretching 4 times or more in a drawing bath set at a temperature of 5 to +9% and a temperature range of 20°C to 70°C. .

The present invention will be explained in detail below.

The flame-retardant acrylic polymer used in the present invention is:

50-85% by weight of acrylonitrile and other monomers copolymerizable with acrylonitrile and 15-50% by weight
It is obtained by copolymerizing vinylidene chloride and a hydrophilic olefinic monomer having 0.4 to 3 weight by weight of sulfonic acid groups by a conventional method.

The polymerization method for these copolymers may be any commonly known polymerization method for vinyl monomers. For example, aqueous suspension polymerization using a redox catalyst, solution polymerization, emulsion polymerization, etc. are generally used. However, the present invention is not limited in any way by the polymerization method and polymerization conditions. □Other monomers copolymerizable with acrylonitrile used in the present invention include acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, acrylamide, and methacrylamide.

maleimide, β-aminoethyl methacrylate.

Examples include, but are not limited to, acrylamide, methacrylamide, and vinyl acetate.

However, among other monomers, vinylidene chloride.

Hydrophilic olefinic monomers having sulfonic acid groups are excluded.

Examples of the hydrophilic olefin monomer having a sulfonic acid group include sulfonic acids such as methallyl sulfonic acid, styrene sulfonic acid, and allyl sulfonic acid, and salts thereof (eg, sodium, potassium, and ammonium salts).

The polymer thus obtained is dissolved in nitric acid, a zinc chloride aqueous solution, a Rodan salt aqueous solution, dimethylformamide, etc. to prepare a spinning stock solution. Particularly preferred in the present invention is a nitric acid aqueous solution.

When using nitric acid as a solvent, the nitric acid concentration is 60-80%.

Preferably for 100 parts of 63-70 nitric acid solution.

A spinning stock solution is obtained by dissolving the polymer in a proportion of 10 to 40 parts, preferably 15 to 20 parts, and maintaining the temperature of the stock solution at 20° C. or less during dissolution to suppress the oxidation reaction caused by nitric acid. This spinning dope is then spun into a coagulation bath having a concentration higher than the critical concentration.

The critical concentration in wet spinning using nitric acid as a solvent varies depending on the concentration of the solvent used, the concentration of the polymer, the concentration of the coagulation bath, etc., but is centered around 3 g.

Similarly, when dimethylformamide is used as a solvent, the critical concentration is around 53%, and when a zinc chloride aqueous solution is used as a solvent, the critical concentration is around 40%.

Spinning using nitric acid as a solvent is performed in a coagulation bath in which the nitric acid concentration is adjusted to 40% or more, preferably 48% or less.

Spinning is carried out using a nozzle tube that can set the spinning draft to more than 5.

Here, the spinning draft rate is expressed by the following formula.

Spinning draft = (winding roller speed) / (linear speed of spinning dope discharged from the nozzle hole) If the coagulation bath has less than the critical concentration, the spinning draft will not reach 5, and the resulting fiber will have deep coloring. poor. If the concentration of the coagulation bath exceeds the critical concentration + 9 degrees, adhesion and agglutination between fibers are likely to occur.

If the spinning draft is less than 5, the fibers will sag in the coagulation bath, and the fibers will wrap around the rotating parts, reducing spinning operability, and the resulting fibers will lack deep color development. Become.

When the spinning draft is set to more than 5, the fibers are stretched in a straight line in the coagulation bath, and the higher the spinning draft, the richer the color development of the resulting fibers.

The critical concentration as used in the present invention means the concentration of the solvent in the coagulation bath at which the maximum spinning speed is at a minimum or no spinning is possible, and where the concentration on either side of the maximum spinning speed has a spinnable region.

When spinning in a coagulation bath having a concentration higher than the critical concentration, the coagulated fibers meander in the coagulation bath, and the resulting fibers become cloudy and completely lose their transparency. therefore,
In conventional spinning, coagulation was performed in a solvent concentration lower than the critical concentration.

The effects of the present invention will be explained based on the following technical ideas.

That is, during wet coagulation, the spinning stock solution discharged into the coagulation bath precipitates a polymer as the solvent concentration decreases, which is known as precipitation coagulation.

The coagulated fibers produced by precipitation and coagulation contain a large amount of solvent at the coagulation bath concentration between the precipitated polymers, forming an extremely porous structure. The space occupied by the solvent is replaced with water by washing and then collapsed as the water evaporates in the drying process, and the precipitated polymer adheres to form acrylic fibers.

In particular, flame-retardant acrylic fibers containing a high percentage of vinylidene chloride, which has strong lipophilic properties, contain a lipophilic phase in the precipitated polymer, and the bondability of the precipitated polymer is weak, resulting in fiber cracking due to external force and optical uniformity. This results in a lack of deep color development.

Therefore, in order to improve the overall abrasion resistance and deep color development, it is important to uniformize the adhesion area of the precipitated polymer. The present inventor immersed the coagulated fiber in a solvent again, fluidized the precipitated polymer, and simultaneously stretched it.
The aim was to compress the inter-polymer portions of the precipitated polymers to improve the adhesion of the precipitated polymers.

Re-soaking the coagulated fibers in a solvent requires fluidizing the precipitated polymer, and under such conditions the coagulated fibers conventionally obtained by wet coagulation will dissolve.

The thinner the precipitated polymer is, the faster it dissolves, and the thicker it is, the slower it is.

Thicken the surface of the precipitated polymer layer of the coagulated fiber.

By making the inside thinner, the inside can be fluidized and brought into close contact without dissolving and cutting the coagulated fibers. Flame-retardant acrylic fibers with excellent abrasion resistance and deep coloring can only be produced by an integral combination of a coagulation method that forms the structure of such coagulated fibers and a stretching treatment in a solvent bath with predetermined conditions. is obtained.

A technical means of making the coagulated fiber structure thicker in one surface layer and thinner in the inner layer is obtained by coagulating in a coagulating bath with a solvent concentration higher than the critical concentration and at a higher spinning draft than conventionally available.

When a coagulated fiber having precipitated polymers gathered in a thick layer on the surface layer of the fiber is stretched in a solvent bath, the fiber can be stretched at a high stretching ratio without being dissolved.

It goes without saying that in the stretching treatment of fibers in a solvent bath, the solvent concentration and temperature of the solvent bath both have upper limits and are set within a range that does not dissolve the % coagulated fibers.

The flame-retardant acrylic fiber obtained by washing the fiber thus obtained with water, completely removing the solvent, stretching, drying, and heat-treating the fiber has poor abrasion resistance and cannot provide deep color development. Remove from coagulation bath.

By stretching at a predetermined ratio in a solvent drawing bath with a predetermined solvent concentration and solvent temperature, flame-retardant acrylic fibers with excellent abrasion resistance and deep coloring can be obtained.

When coagulated fibers that do not satisfy the coagulation conditions of the present invention are subjected to the entire solvent drawing treatment under the conditions specified in the present invention, the coagulated fibers may be dissolved or adhesion between fibers may occur in the solvent drawing bath.
The fiber has poor abrasion resistance, lacks deep color development, and has a dull tone.

When using nitric acid, preferably the concentration of the solvent drawing bath is 40
It is sufficient that the bath temperature is 25 to 70°C and the stretching ratio is 4 times or more.

The higher the concentration of the solvent drawing bath, the better the wear resistance.

Easy to obtain deep coloring. When the critical concentration factor is less than 5%, the abrasion resistance and color development deteriorate, and at the same time, the stretchability also deteriorates. If the critical concentration exceeds +9, adhesion and agglutination between fibers tend to occur, which is not good.

The higher the temperature of the solvent stretching bath, the better the abrasion resistance and color development, but at temperatures below 25°C, the stretching property decreases and the 70
If the temperature exceeds .degree. C., adhesion between fibers tends to occur, so 40 to 65.degree. C. is preferable.

The higher the stretching ratio in the solvent stretching bath, the more excellent the abrasion resistance and coloring properties can be obtained. Abrasion resistant when stretched in a solvent stretching bath at a stretch ratio of less than 4 times.

Color development deteriorates.

Fibers produced within the scope of the present invention are subjected to one conventional water washing treatment to remove the solvent to less than 0.1 m. The washing method may be any of the commonly used methods such as immersion AC washing, net washing, and vibro washing. Of the fibers from which the solvent has been removed.

Fibers that have not been sufficiently drawn in a solvent drawing bath have low strength, so it is preferable to re-draw them in hot water or steam, but even in this case, the deep color development does not deteriorate. In other words, if the fiber has been stretched more than 4 times in a solvent drawing bath, there is no harm in re-stretching it depending on the application.

The fibers from which the solvent has been removed or the fibers that have been redrawn after the solvent has been removed are dried to remove the moisture contained in the fibers. As a drying method, any of the commonly used drum dryers, cylinder dryers, net dryers, and other known methods may be used.

The fibers from which water has been removed are then subjected to heat relaxation treatment.

As a method for thermal relaxation, any method may be used as long as it can be contracted in a heated atmosphere such as in pressurized steam, hot air, hot water, or between hot plates. Furthermore, the fibers from which moisture has been removed are placed in pressurized steam.

Even when stretched, the abrasion resistance and color development properties do not deteriorate.

Deep color development is a visual sensory evaluation standard and is poorly quantitative.

As a result of intensive research into deep color development, we discovered that it greatly depends on the amount of light transmitted in the fiber axis direction. The relationship between the amount of transmitted light of the fiber and the deep coloring property obtained in experiments including various comparative examples and examples is found to be correlated in the shaded area in the graph of FIG.

To measure the amount of transmitted light, a fiber bundle with a length of 2-2 is made using the fiber bundle fixing device shown in Fig. 1, and the fiber bundle is placed in an ori/bath BH-
This is carried out using a type 2 microscope with a white light source and a setting of 100x without a filter. Under the microscope, adjust the field of view to the area that shows average brightness and measure the exposure time. The reciprocal of the exposure time is the amount of transmitted light and is expressed in units of 5 ec-''.

To prepare a sample for measuring the amount of transmitted light, pass the fiber 4 through part of the fiber bundle fixing device shown in Fig. 1 (Fig. 2 shows its side), then apply a load 7 of 20Of with the presser metal fitting 2, and 2 with the setscrew 3, and then the front 5 and back 6 parts of the fiber bundle protruding from the flat part of the fiber bundle fixing device (Fig. 2)
It can be made by precisely cutting it with a knife.

The amount of transmitted light is affected by the degree of fiber filling. therefore,
fIl1. which measures the amount of transmitted light. It goes without saying that fibers are significant only when they have the same cross-sectional shape and the same denier.

The degree of deep color development is 3.5 compared to the 2.5 grade of commercial products.
If you are above grade level, you can tell the difference at a glance.

Figure 4 shows a fiber bundle fixing device for measuring abrasion resistance.

7 is a vinyl chloride tube with an inner diameter of 5 mm, 8 is a cellophane tape convergence area, and 9 is fIl, a fiber bundle tip.

Figure 5 shows the abrasion resistance measuring device, 10 is a load, 11 is a load receiver, 11 is a support tube, 13 is a 40 mesh stainless wire mesh, 14 is a rubber plate, 15 is a wire mesh presser, 16 is a rotation It is a stand.

The amount of wear resistance is measured using the wear resistance measurement device shown in Fig. 5. The fibers to be measured were crimped and stretched using normal pressure steam.
Diameter 7mmφ, length 2c! II.Bundle into a cylindrical shape, tip part 3
Remove dew and wrap with commercially available cellophane tape to a hardness of 90. The hardness is measured by pressing the center of one cylindrical side using a new hardness tester manufactured by Toyo Seiki.

The columnar sample was pushed into a vinyl chloride tube with an inner diameter of 7 mm and its weight W1 was measured. Next, push the support cylinder of the wear measuring machine shown in Fig. 5 from the lower end, place a load of 20Of on the upper part of the support cylinder, and then move the rotary plate lined with a commercially available 40 mesh stainless wire mesh too many times (1 hour). Rotate.

After removing the fiber powder mixed inside the sample after the abrasion treatment, the weight W is measured.

The abrasion resistance of fibers is expressed by the abrasion resistance of equation (1), which is 4.5
If it is less than or equal to 50%, it has good wear resistance.

Amount of wear resistance == (w, -W2) /WyuX100...
(1) What are the requirements for flame retardancy of flame retardant acrylic fibers?

It varies depending on the product field and product specifications used, and it is difficult to draw a clear line, but it can be obtained using the -7201 oxygen index method at JI5%, or O,I (Limited Oxid
ationIndex) of 22 or more is defined as flame-retardant acrylic fiber in the present invention.

Flame retardancy can be increased by attaching and kneading various additives, but the present invention has the purpose of meeting various demands for flame retardancy by increasing the flame retardance of the fiber itself. . Therefore, even if antimony pentoxide or antimony trioxide is added to the fiber itself, as long as the abrasion resistance and deep color development that are the objectives of the present invention are not impaired,
I don't mind.

The present invention will be explained in more detail with reference to Examples below.

Example 1 A combination of ammonium persulfate and acidic sodium sulfite was used as a polymerization catalyst, and the pH was adjusted to 2.5 with sulfuric acid at 55°C.
acrylonitrile (hereinafter referred to as AN), vinylidene chloride (hereinafter referred to as VC), and sodium methacrylsulfonate (hereinafter referred to as MS) in water at the proportions shown in Table 1.

Polymerization was carried out for 5 hours to obtain the polymers shown in Table 1. This polymer was mixed with 100% of nitric acid water having the solvent nitric acid concentration shown in Table 1 at 0°C.
It was dissolved in a ratio of 16f to F to give a spinning stock solution.

Then, it was discharged into a coagulation bath of 42% nitric acid water at 0° C. having the critical concentration shown in Table 1 using a nozzle with a hole diameter of 0.50 and a number of holes of 100, and taken out from the coagulation bath at a speed of 5 m/rtix. The fibers that had been stretched 8.0 times in a solvent drawing bath with a nitric acid concentration of 42 times and a bath temperature of 65°C were washed with water, thoroughly dried in hot air at 130°C, and then stretched in steam at 115°C. Heat relaxation treatment was performed.

Comparative Example 1 with a VC content of 52% by weight has poor wear resistance. Comparative Example 2, which has a content of 14% by weight, lacks flame retardancy. V
Example 1 of the present invention in which the C content is 49% by weight and 15% by weight.
2, O, I is 30.21, and has high flame retardancy.

The lower the VC content, the better the abrasion resistance, but it was 4% in Inventive Example 1 and 2% in Inventive Example 2.

In both cases, the amount of wear resistance is significantly reduced compared to the conventional method.

Table 1 Example 2 Polymerization was carried out in the same manner as in Example 1 at a weight ratio of AN/VC/MS=69.5/3010.5 to obtain a polymer.

This polymer was dissolved at a ratio of 16f in 100t of a 71% by weight nitric acid aqueous solution at 0°C to prepare a spinning stock solution at 7'C.

It was then removed from the coagulation bath at a speed of 6 m/- using the spinning nozzle shown in Table 2. At this time, the critical concentration is 40.5 inches, and the coagulation bath concentration is 42 inches. Subsequently, the film was stretched 8.0 times in a solvent stretching bath with a nitric acid concentration of 42% by weight and a bath temperature of 65°C. After the stretched fibers were washed with water, they were thoroughly dried in hot air at 130°C and subjected to a thermal relaxation treatment with steam at 120°C.

Comparative Example 3, in which the spinning draft is 3.9, has high abrasion resistance and poor deep color development.

Examples 3 and 4.5 of the present invention, in which the spinning draft is 5 or more, have low abrasion resistance and deep color development.

Table 2 Example 3 The polymer obtained in Example 2 was dissolved at 0° C. in a ratio of 16F to 100 tons of a 7111 L aqueous dinitric acid solution to obtain a spinning stock solution.

Then, using a nozzle with a hole diameter of o-alJφ and a number of holes of 50, -
It was discharged into a 42% by weight aqueous nitric acid solution at 1°C and taken out from the coagulation bath at a speed of 6 m/-. At this time, the critical concentration is 40.
It was 5chi. Subsequently, the film was stretched 8 times in a solvent stretching bath having the nitric acid concentration and temperature shown in Table 3. The fibers that have been stretched are washed with water, thoroughly dried in hot air at 130°C, and then
Thermal relaxation treatment was performed in steam at 0°C.

Comparative Example 4, in which the solvent drawing bath temperature was as low as 15° C., had a high abrasion resistance of 7 inches and lacked deep color development. Furthermore, in Comparative Example 5, where the solvent drawing bath temperature was as high as 75° C., deep color development was obtained, but adhesion of single fibers occurred, which was not good. Perhaps for this reason, the amount of wear resistance also increases, which is not good.

Examples 6, 7, and 8 of the present invention have low abrasion resistance and are good, and have deep color development.

Comparative Example 6, in which the solvent stretching bath concentration was 40% by weight, was not good because both the wear resistance and deep color development were insufficient. Comparative Example 7, in which the solvent drawing bath concentration was 49% by weight, had deep color development, but like Comparative Example 5, adhesion between single fibers occurred and the wear resistance was high, which was not good. Inventive Example 9 has low abrasion resistance and good deep color development.

Table 3 Example 4 The polymer obtained in Example 2 was dissolved in a 71% by weight nitric acid aqueous solution at 0°C.
It was dissolved at a ratio of 169 to 0t to obtain a spinning stock solution.

Then, using a nozzle with a hole diameter of 08.6 mm and a number of holes of 50,
'C, discharged into a nitric acid aqueous solution of 41 wt., 6 m/mi
It was removed from the coagulation bath at a rate of s. At this time, the critical concentration is 4
It was 0.5-. Continuing, nitric acid concentration 42wt-1
It was stretched to the ratio shown in Table 4 in a solvent stretching bath at a bath temperature of 65°C. After that, it was thoroughly washed with water, and then stretched in boiling water so that the overall stretching ratio was 8 times, and then at 130°C.
The sample was thoroughly dried in hot air and subjected to thermal relaxation treatment in steam at 120°C.

Comparative Example 8 has a stretching ratio of 3 times in a solvent stretching bath.

Both abrasion resistance and deep color development are poor.

Invention example 10 where the stretching ratio in the solvent stretching bath is 4 times and 8 times
．． No. 11 has good wear resistance and deep color development.

Table 4 Effects of the Invention The flame retardant acrylic fiber of the present invention is more effective than the conventional one.
It is a fiber that has abrasion resistance and deep color development, and by using this fiber, it is possible to obtain textile products with high commercial value and a high degree of flame retardancy.

[Brief explanation of the drawing]

Figure 1 is a front view of the fiber bundle fixing device, Figure 2 is a side view of the fiber bundle fixing device, Figure 3 is a graph showing the relationship between transmitted light amount and deep color development, and Figure 4 is abrasion resistance measurement. Fig. 5 shows an abrasion resistance measuring device. l: Fiber bundle fixing groove, 2: Holding metal fitting, 3: Set screw, 4:
Fiber bundle, 5: front side of fiber bundle fixing device, 6: back side, 7: vinyl chloride tube with inner diameter of 5 φ, 8: cellophane tape concentration area, 9: l fiber bundle tip, 1G: load, 11: load The receiver is a stand, 12: Support cylinder, TS: 4o mesh stainless steel wire mesh, 14: Rubber plate, 15: Wire mesh holder, 16 2 Rotating table Patent applicant Asahi Kasei Corporation Fig. 1 Fig. 2 Fig. 3 i + light intensity (seg'xlO') Figure 4 Figure 5

Claims (2)

[Claims] (1) 50 to 85% by weight of acrylonitrile and other monomers copolymerizable with acrylonitrile;
It is composed of a flame-retardant acrylic polymer consisting of vinylidene chloride (wt%) and a hydrophilic olefin monomer having sulfonic acid groups (0.4 to 3 wt%). Flame-retardant acrylic fiber with excellent abrasion resistance and color development, with deep color development of grade 3.5 or higher. (2) 50 to 85% by weight of acrylonitrile and other monomers copolymerizable with acrylonitrile;
When wet-spinning a flame-retardant acrylic polymer consisting of vinylidene chloride (wt%) and a hydrophilic olefinic monomer having sulfonic acid groups (0.4 to 3 wt%), it is spun into a coagulation bath with a concentration higher than the critical concentration. The spinning draft during coagulation is 5 or more,
Then the range of +0.5 to +9% from the coagulation bath concentration and 2
A method for producing flame-retardant acrylic fibers with excellent abrasion resistance and color development, characterized by stretching 4 times or more in a drawing bath set at a temperature in the range of 0°C to 70°C.