JPH04316616A - Polyacrylonitrile flame-resistant fiber and production thereof - Google Patents

Abstract

PURPOSE:To provide an acrylonitrile polymer flame-resistant fiber excellent in the flame resistance and the post-processability such as spinnability, reduced in the aging change of the flame resistance, having stable flame resistance and having good touch, etc., after processed. CONSTITUTION:When an acrylonitrile polymer fiber is subjected to an oxidation treatment in an oxidative atmosphere, the oxidation treatment is performed so as to maintain the single filament strength, elongation and limit oxygen index of the fiber at >=2.5g/d, >=20% and 25-30, respectively. The surface of the treated fiber is coated with an organic flame-resistant compound in an amount of 0.1-5.0wt.% to give a limit oxygen index of >=40.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to acrylonitrile-based flame-resistant fibers which are subjected to flame-retardant treatment to impart flame resistance, and a method for producing the same.
In particular, the present invention relates to an acrylonitrile-based flame-resistant fiber that has excellent flame resistance, high single fiber strength and elongation, and excellent post-processability such as spinnability, and a method for producing the same.

0002

[Prior Art] It has been known that heat-treating acrylonitrile fibers in an oxidizing atmosphere imparts flame resistance to the acrylonitrile fibers, resulting in acrylonitrile flame-resistant fibers with excellent flame resistance. . The acrylonitrile-based flame-resistant fibers obtained in this way have excellent properties such as flame resistance and heat resistance, so they are used in a wide range of fields as an alternative to asbestos in flame-resistant cloth, packing, firefighting clothing, insulation materials, etc. It is being used.

However, when acrylonitrile fibers are heat-treated in an oxidizing atmosphere as described above, the strength and elongation of the acrylonitrile fibers gradually decrease as the oxidation progresses, and as described above, sufficient flame resistance cannot be achieved. When this is applied, the elongation of the acrylonitrile fiber, which was originally 15 to 45%, decreases to about 10%, resulting in a fiber with extremely low spinnability and other post-processability. Problems such as thread breakage, increased cotton shedding, and a large amount of fuzz occurred.

[0004] Therefore, in the past, various studies have been carried out to solve such problems.
As shown in Publication No. 911, etc., acrylonitrile fibers are mixed with trace amounts of aluminum compounds, iron compounds, phosphorus compounds, etc., and then the acrylonitrile fibers are heat-treated in an oxidizing atmosphere as described above to make them flame resistant. A method for producing superior acrylonitrile-based flame-resistant fibers has been developed.

However, even when acrylonitrile-based flame-resistant fibers are produced in this manner, the obtained acrylonitrile-based flame-resistant fibers have the drawbacks of low fiber strength and brittleness, and post-processing properties such as spinnability are poor. It was still not satisfactory.

[0006]Furthermore, the flame-resistant acrylonitrile fibers produced in this manner have the problem of insufficient flame-resistance stability and gradual decrease in flame resistance, and furthermore, the texture after processing deteriorates. There was a problem.

[0007]

[Problems to be Solved by the Invention] It is an object of the present invention to solve the above-mentioned problems with acrylonitrile-based flame-resistant fibers, and to impart flame resistance to acrylonitrile-based fibers by subjecting them to flame-retardant treatment. As a result, the strength and elongation of single fibers do not decrease as much as with conventional products, and it has excellent flame resistance and excellent post-processing properties such as spinnability.Furthermore, there is little change in flame resistance over time, and it has stable flame resistance. It is an object of the present invention to provide an acrylonitrile-based flame-resistant fiber that can be obtained and has a good texture after processing.

[0008]

[Means for Solving the Problems] In the present invention, as an acrylonitrile flame-resistant fiber that solves the above-mentioned problems, it has a single fiber strength of 2.5 g/d or more, an elongation of 20% or more, and a limiting oxygen index of 25 to 25. We have developed an acrylonitrile-based flame-resistant fiber containing 0.1 to 5.0% by weight of at least one type of organic flame-retardant compound in an acrylonitrile-based fiber with a limiting oxygen index of 40 or more. It is.

In addition, in the present invention, in producing the above-mentioned acrylonitrile-based flame-resistant fibers, acrylonitrile-based fibers containing 95 mol% or more of an acrylonitrile component are heated in an oxidizing atmosphere at 300° C. or below with a limiting oxygen index of 25. After the acrylonitrile fibers were oxidized to a temperature of ~30, an organic flame retardant compound was attached to the surface of the acrylonitrile fibers.

[0010] Here, as mentioned above, the reason for using the acrylonitrile fiber containing 95 mol% or more of the acrylonitrile component is that if the acrylonitrile component is less than this, when the oxidation treatment is performed as described above, -CN contained in the acrylonitrile component
This is because the cyclization of groups decreases, making it impossible to obtain sufficient flame resistance and flame resistance. Preferably, acrylonitrile fibers containing 97 mol % or more of an acrylonitrile component are used.

On the other hand, the components to be copolymerized with this acrylonitrile component include acrylic acid, methacrylic acid, allylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, or salts and esters thereof, vinyl chloride, and vinylidene chloride. Examples include halogen compounds such as.

[0012] There is no particular limitation on the thickness of the acrylonitrile fiber used in this invention, but it is usually 0.5d or more, and generally 1.
-10d should be used.

[0013] When oxidizing the acrylonitrile fibers as described above, it is usually 200 to 300%
The treatment is carried out at a temperature of 220 to 280 degrees Celsius, preferably 220 to 280 degrees Celsius, in an oxidizing atmosphere such as air or sulfur dioxide gas for 10 minutes or more, so that the limiting oxygen index is in the range of 25 to 30. When oxidizing acrylonitrile fibers in this way, if the limiting oxygen index is within the range of 25 to 30, there will be less decrease in fiber strength and elongation due to oxidation treatment of acrylonitrile fibers.
The single fiber strength is maintained at 2.5 g/d or more and the elongation is maintained at 20% or more.

[0014] After the acrylonitrile fibers have been oxidized in this way, an organic flame retardant compound is attached to the surface of the acrylonitrile fibers so that the limiting oxygen index thereof becomes 40 or more.

[0015] Examples of organic flame retardant compounds include phosphates and their salts, phosphonic acid esters, organic phosphorus compounds such as phosphoric acid urea condensates, guanidine compounds,
Organic nitrogen compounds such as melanin can be used,
In particular, it is preferable to use phosphate-based and guanidine-based compounds because they exhibit excellent properties. In addition, the reason for using organic flame retardant compounds is that commonly used inorganic flame retardants such as zinc chloride, boric acid, phosphoric acid, and zirconium chloride have sufficient flame retardant stability. This is because the flame retardant effect gradually decreases, and the texture after processing also deteriorates.

[0016] In addition, when attaching the organic flame retardant compound as described above to the acrylonitrile fiber, the amount of the attached amount is set to 0.1 to 5.0% by weight. If it is less than 5.0% by weight, the flame-resistant performance of the resulting acrylonitrile-based flame-resistant fiber will deteriorate, while if it exceeds 5.0% by weight, the obtained acrylonitrile-based flame-resistant fiber will become sticky due to this deposit, and its spinnability will be significantly reduced. It's for a reason. In addition, in order to attach the above-mentioned organic flame retardant compound to acrylonitrile fiber, a known attachment method can be used, such as impregnation, padding, coating, etc. Make sure to attach it using a method.

The limiting oxygen index (LOI) used in the present invention is defined in JIS-K7201, and its value was determined by conducting the following tests.

[0018] To determine the limiting oxygen index (LOI), cut the fiber to a length of 51 mm, open it with a hand card, take about 0.5 g of cotton, and stretch it uniformly to a length of 25 cm. A twisted rod was made by twisting the material 70 times using a twisting machine and folding it in half. Then, the upper end of the twisted rod is brought into contact with the flame in a mixed gas of nitrogen gas and oxygen gas, and when the twisted rod burns 5 cm, the oxygen gas concentration in the mixed gas is measured and determined by the following formula. I did it like that. Limiting oxygen index (LOI) = [oxygen gas/(nitrogen gas + oxygen gas)] x 100

[0019]

[Function] In this invention, when acrylonitrile fibers are oxidized in an oxidizing atmosphere as described above, the critical oxygen index of the acrylonitrile fibers is 25 to 30.
As a result, this oxidation treatment caused little decrease in the single fiber strength and elongation of the acrylonitrile fiber, and the single fiber strength was kept at 2.5 g/d or more and the elongation at 20% or more. You will be able to do it.

Then, 0.0% of an organic flame retardant compound is applied to the surface of the acrylonitrile fiber that has been oxidized as described above.
By adhering 1 to 5.0% by weight, the critical oxygen index is 40 or higher, so it exhibits sufficient heat resistance and flame resistance. Acrylonitrile-based flame-resistant fibers with excellent properties can now be obtained.

[0021]

EXAMPLES Examples of the present invention will be described in detail below, and comparative examples will be given to demonstrate that the acrylonitrile flame-resistant fibers produced according to the examples of the present invention exhibit excellent properties.

(Examples 1 to 3 and Comparative Examples 1 and 2) In these Examples and Comparative Examples, acrylonitrile 99
D
A solution dissolved in MF was used as a spinning stock solution.

[0023] Then, this spinning stock solution was
A fiber bundle with a single fiber degree of 2.0 d was obtained by wet spinning using a conventional method from a spinneret with a hole diameter of 0.055 mmφ.

Next, the fiber bundles thus obtained were each oxidized in air at 250° C. while being stretched to a constant length.

[0025] Here, in carrying out the oxidation treatment,
The treatment time was as shown in Table 1 below, 15 minutes in Example 1, 20 minutes in Example 2, and 30 minutes in Example 3.
20 minutes in Comparative Example 1, 60 minutes in Comparative Example 2,
The oxidation treatment was carried out in the above atmosphere, and the limiting oxygen index (LOI) of each fiber after the oxidation treatment was measured, and the results are shown in the table.

[0026] For each of the acrylonitrile fibers of Examples 1 to 3 and Comparative Examples 1 and 2 which were oxidized as described above, guanidine phosphate was added as an organic flame retardant compound in the proportions shown in Table 1 below. The limiting oxygen index (LOI) of each fiber was measured after attachment, and the results are also shown in the same table.

[0027]

[Table 1]

Next, Example 1 obtained as described above
Single fiber strength (g/d) and elongation (%) for each acrylonitrile flame-resistant fiber of ~3 and Comparative Examples 1 and 2, respectively.
At the same time, the spinnability of each acrylonitrile-based flame-resistant fiber was also evaluated, and the results are shown in Table 2 below. Regarding the evaluation of spinnability, spinning was carried out under normal operating conditions, and the spinning process, that is, carding, drawing,
If the number of troubles during the spinning process is similar to normal acrylonitrile fibers and is almost non-existent, it is indicated by ○, if there are troubles, the product will become spun thread-like, △, and if there are troubles, it will not become thread-like, it will be indicated by ×. .

[0029]

[Table 2]

[0030] As is clear from the results, Examples 1-
Each of the acrylonitrile-based flame-resistant fibers in No. 3 had higher single fiber strength (g/d) and elongation (%
) was high, there were fewer yarn breakages during spinning, and the spinning properties were excellent. In addition, in Comparative Example 1, the single fiber strength (g/d) and elongation (%) were high like each of the acrylonitrile flame-resistant fibers of Examples 1 to 3, but the attached guanidine phosphate Because of the large amount of , the fibers were sticky and the spinnability was poor.

[0031]

Effects of the Invention As detailed above, in this invention, in order to impart flame resistance to acrylonitrile fibers, the acrylonitrile fibers are oxidized in an oxidizing atmosphere until the limiting oxygen index reaches 25 to 30. After that, an organic flame retardant compound was attached to the surface of this acrylonitrile fiber to make its limiting oxygen index 40 or more, so the single fiber strength and elongation of the acrylonitrile fiber decreased due to oxidation treatment. The single fiber strength is maintained at 2.5 g/d or higher, and the elongation is maintained at 20% or higher.It has excellent flame resistance and excellent post-processing properties such as spinnability. It became possible to obtain flame-resistant acrylonitrile fibers.

Furthermore, in the present invention, since the organic flame retardant compound is attached to the surface of the oxidized acrylonitrile fiber as described above, the flame retardant compound gradually becomes It is possible to obtain an acrylonitrile-based flame-resistant fiber that has stable flame resistance and good texture after processing without reducing its flame-retardant effect or deteriorating the texture after processing. Became.

Claims (2)

[Claims] [Claim 1] Single fiber strength 2.5 g/d or more, elongation 2
Acrylonitrile fibers containing 0.1 to 5.0% by weight of at least one type of organic flame retardant compound and having a limiting oxygen index of 40 or more in an acrylonitrile fiber containing 0% or more and a limiting oxygen index of 25 to 30. Acrylonitrile-based flame-resistant fiber characterized by: 2. After oxidizing an acrylonitrile fiber containing 95 mol% or more of an acrylonitrile component in an oxidizing atmosphere at 300°C or lower until the limiting oxygen index reaches 25 to 30, the surface of the acrylonitrile fiber is A method for producing an acrylonitrile-based flame-resistant fiber, which comprises adhering a flame-retardant compound.