JP6065479B2 - Radiation shielding acrylonitrile fiber, fiber structure containing the fiber, and method for producing the same - Google Patents

Description

The present invention relates to a radiation shielding acrylonitrile fiber, a fiber structure containing the fiber, and a method for producing the same.

Conventionally, a radiation shielding effect has been obtained using barium sulfate. For example, an X-ray contrasting rayon fiber (Patent Document 1) containing 60% or more of barium sulfate with respect to cellulose and a rayon fiber (Patent Document 2) containing 35 to 80% by weight of barium sulfate are disclosed. Patent Document 3 discloses that a mixture of 88 wt% tungsten powder and 4 wt% barium sulfate powder is kneaded with a thermoplastic elastomer and formed into a sheet shape. However, since these techniques contain a large amount of barium sulfate or the like, the strength is lowered, and in the case of fibers, it is difficult to reduce the fineness.

Patent Document 4 discloses a fiber in which barium sulfate is contained in the core of a fiber having a core-sheath structure. Such fibers have a strength of 2.7 cN / dtex or more, but once a tip is formed by adding barium sulfate to a thermoplastic polymer for the core, this is used to make the thermoplastic for the sheath. A time-consuming production method of polymer / core-sheath composite spinning must be employed.

Japanese Patent Publication No.55-017801 JP 61-102411 A JP 2004-077170 A JP 11-337682 A

As described above, in the prior art, problems remain in terms of strength, fineness, or simplification of the manufacturing process. An object of the present invention is to provide an acrylonitrile fiber that can solve these problems and has an excellent radiation shielding effect.

The above object of the present invention is achieved by the following means.
(1) A radiation shielding acrylonitrile fiber containing an acrylonitrile polymer and barium sulfate fine particles having an average particle diameter of 0.01 to 0.05 μm.
(2) The radiation shielding acrylonitrile fiber according to (1), wherein the content of the barium sulfate fine particles is 5 to 35 parts by weight with respect to 100 parts by weight of the acrylonitrile polymer.
(3) The radiation shielding acrylonitrile fiber according to (1) or (2), wherein the tensile strength is 2.0 to 3.5 cN / dtex.
(4) The radiation shielding acrylonitrile fiber according to any one of (1) to (3), wherein the fineness is 0.5 to 3.3 dtex.
(5) A fiber structure containing the radiation shielding acrylonitrile fiber according to any one of (1) to ( 4 ).
(6) A method for producing radiation-shielding acrylonitrile fiber containing acrylonitrile polymer and barium sulfate fine particles having an average particle size of 0.01 to 0.5 μm, wherein the barium sulfate fine particles are added to the acrylonitrile polymer solution. A method for producing a radiation-shielding acrylonitrile fiber, comprising spinning a spinning dope obtained by mixing an aqueous dispersion.

According to the present invention, an acrylonitrile fiber having an excellent radiation shielding effect can be obtained by a simpler method with a smaller barium sulfate content as compared with the prior art. For this reason, the acrylonitrile fiber of the present invention has a fiber strength comparable to that of ordinary acrylic fibers, can be easily subjected to spinning processing, nonwoven fabric processing, etc., and can be made finer and lighter. Has been. Therefore, such fibers can be used in various forms of products that require radiation shielding properties, such as radiation protective clothing and radiation shielding sheets.

The acrylonitrile-based polymer in the present invention is such that 40% by weight or more of the polymerization composition is acrylonitrile, preferably 50% by weight or more, and more preferably 80% by weight or more is acrylonitrile. Therefore, as the acrylonitrile-based polymer, a copolymer of acrylonitrile and another monomer can be employed in addition to the acrylonitrile homopolymer. Other monomers in the copolymer are not particularly limited, but vinyl halides and vinylidene halides; (meth) acrylic acid esters (note that (meth) is indicated with or without the word “meta”. Sulfonic acid group-containing monomers such as methallyl sulfonic acid and p-styrene sulfonic acid and salts thereof; carboxylic acid group-containing monomers such as (meth) acrylic acid and itaconic acid and salts thereof; acrylamide, styrene, Examples include vinyl acetate.

In the present invention, the barium sulfate fine particles in the present invention exhibit a radiation shielding action. It is desirable that the barium sulfate fine particles are small. The smaller the particles, the greater the number of particles per unit weight, and the larger the area occupied by the barium sulfate particles in the projected area of the fiber, the more effective the radiation shielding effect with a smaller amount of barium sulfate particles added. Can be expressed. From this viewpoint, the average particle diameter of the barium sulfate fine particles in the present invention is 0.01 to 0.5 μm, preferably 0.01 to 0.1 μm. In addition to the radiation shielding effect, when the average particle diameter exceeds 0.5 μm, the fiber strength decreases greatly. When the average particle diameter is less than 0.01 μm, This is not desirable because the amount of falling barium sulfate fine particles increases. As such barium sulfate fine particles, sedimentary barium sulfate is suitable. Specifically, Varifine BF-1, Varifine BF-21 (manufactured by Sakai Chemical Industry Co., Ltd.), sedimentary barium sulfate B-34 (East) Shin Kasei Co., Ltd.).

The barium sulfate fine particles are preferably contained in an amount of 5 to 35 parts by weight, more preferably 10 to 35 parts by weight with respect to 100 parts by weight of the acrylonitrile polymer constituting the fiber. If the content is less than 5 parts by weight, sufficient radiation shielding action cannot be obtained, and if it exceeds 35 parts by weight, a large amount of barium sulfate fine particles are added to the spinning dope in the production method described later. However, at this time, the spinning dope is gelled, so that spinning cannot be performed and fibers cannot be obtained.

Furthermore, in the radiation shielding acrylonitrile fiber of the present invention, the barium sulfate fine particles are uniformly dispersed throughout the fiber from the above viewpoint of obtaining a radiation shielding effect efficiently with a smaller amount of addition of barium sulfate fine particles. A structure is desirable. In the core-sheath structure, the sea-island structure, or the multilayer structure, it is not advantageous from the viewpoint of obtaining a radiation shielding effect efficiently to localize the barium sulfate fine particles only in a specific part such as the core part or only the island part. . Moreover, the effect which can suppress the fall of fiber strength is also acquired by setting it as the structure where the fine particle of barium sulfate is disperse | distributing uniformly to the whole fiber.

In the radiation shielding acrylonitrile fiber of the present invention, the barium sulfate fine particles having a small average particle diameter are uniformly dispersed as described above, whereby the tensile strength of the fiber is 2.0 to 3.5 cN / dtex. The fineness of 0.5 to 3.3 dtex is also possible.

Examples of the fiber structure containing the radiation shielding acrylonitrile fiber of the present invention include yarn, yarn (including wrap yarn), filament, woven fabric, knitted fabric, pile fabric, nonwoven fabric, paper-like material, sheet-like material, laminate, Examples thereof include cotton-like materials (including spherical and massive materials). Specific examples include protective clothing, outerwear, coats, underwear, stomach wraps, supporters, gloves, socks, stockings, pajamas, bathrobes, towels, mats, rugs, carpets, bedding, sheets, and the like. In forming the fiber structure, the radiation-shielding acrylonitrile fiber of the present invention may be used alone, or a publicly used natural fiber, organic fiber, semi-synthetic fiber, synthetic fiber, or inorganic material. A fiber, glass fiber, etc. can also be used together. In addition, what is necessary is just to select suitably the ratio for which the radiation shielding acrylonitrile fiber of this invention accounts in a fiber structure so that the radiation shielding property, mechanical characteristic, etc. which are calculated | required in the use of this fiber structure may be satisfied.

Here, as a means for increasing the radiation shielding rate in the fiber structure of the present invention, it is preferable to use the radiation shielding acrylonitrile fiber of the present invention as much as possible, specifically, preferably 50% by weight or more. The amount is preferably 80% by weight or more, and most preferably 100% if possible. The shape of the fiber structure is preferably a thermal bond nonwoven fabric, a high-density fiber structure such as a high-weight fabric or knitted fabric, and a shape having as few voids as possible. In particular, when the apparent density of the fiber structure is 0.2 g / cm ³ or more, an excellent radiation shielding rate can be exhibited. Here, the apparent density is a value obtained by dividing the weight of the fiber structure by the apparent volume.

Further, in the fiber structure, the finer the fineness of the constituent fibers, the more densely packed, so that the fineness of the radiation shielding acrylonitrile fiber used is preferably 3.3 dtex or less, more preferably 1.7 dtex. The following is desirable. On the other hand, from the viewpoint of ease of processing into a fiber structure, the fineness is preferably 0.5 dtex or more, more preferably 0.8 dtex or more.

As described above, the method for producing the radiation shielding acrylonitrile fiber of the present invention includes mixing a barium sulfate fine particle into a solution in which an acrylonitrile polymer is dissolved in a solvent to prepare a spinning stock solution, and spinning the fiber to spin the fiber. The method of obtaining can be mentioned. Here, examples of the solvent for dissolving the acrylonitrile-based polymer include organic solvents such as dimethylformamide, dimethylacetamide, and dimethylsulfoxide, and inorganic salt solvents such as nitric acid, zinc chloride aqueous solution, and sodium thiocyanate aqueous solution. As spinning conditions, conventionally known spinning conditions can be employed.

The barium sulfate fine particles are preferably mixed as a dispersion liquid such as an aqueous dispersion rather than as dry fine particles. By mixing in a dispersed liquid, the barium sulfate fine particles are not agglomerated in the obtained fiber and can be uniformly dispersed, so that the decrease in fiber strength is suppressed and the radiation shielding action is more efficient. It can be expressed in an experimental manner.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the scope of the present invention is not limited thereto. Parts and percentages in the examples are on a weight basis unless otherwise indicated.

(1) Average particle diameter The average particle diameter was measured by a dynamic light scattering method using ELS-Z (manufactured by Otsuka Electronics Co., Ltd.).

(2) Tensile strength Tensile strength was measured based on JIS-L-1015 "Testing method for chemical fiber staples".

(3) A radiation shielding sample fiber and a heat-fusible polyethylene terephthalate fiber melty 2.2 dtex (manufactured by Unitika Ltd.) are mixed at a ratio of 80:20, a basis weight of 250 g / m ² and a thickness of 1 mm, that is, an apparent density of 0.1. A nonwoven fabric of 25 g / cm ³ was obtained. Using the obtained nonwoven fabric, the penetration dose rate was measured according to JIS-Z-4501 “Lead equivalent test method for X-ray protective equipment”. The condition was 100 kV-12.5 mA and a narrow beam. The radiation shielding rate was calculated from the numerical value of the obtained penetration dose rate by the following formula.
Radiation shielding rate (%) = 1− (transmitted dose rate when sample is placed / transmitted dose rate when sample is not placed) × 100

[Example 1]
An acrylonitrile polymer was prepared by aqueous suspension polymerization of 90% by weight of acrylonitrile, 9% by weight of methyl acrylate, and 1% by weight of sodium methallylsulfonate. On the other hand, barium sulfate BF-21 (average particle diameter 0.05 μm, manufactured by Sakai Chemical Industry Co., Ltd.) was used to prepare an aqueous dispersion having a solid content of 35%. The acrylonitrile polymer is dissolved in a sodium thiocyanate aqueous solution having a concentration of 45% by weight so as to have a concentration of 12% by weight, and then an aqueous dispersion of the barium sulfate fine particles is added and mixed. A spinning dope with a weight ratio of 100: 20 was prepared. The stock solution is extruded into a 15% by weight, -2.0 ° C aqueous sodium thiocyanate solution, then washed with water, stretched 12 times, wet-heat treated at 110 ° C for 10 minutes, and dried and densified with a hot air dryer at 120 ° C. The radiation shielding acrylonitrile fiber of the present invention having 1.0 dtex was prepared. The properties of the obtained fiber are shown in Table 1.

[Example 2]
An acrylonitrile fiber was obtained in the same manner as in Example 1 except that the weight ratio of the acrylonitrile polymer to the barium sulfate fine particles was 100: 3. The properties of the obtained fiber are shown in Table 1.

[Example 3]
An acrylonitrile fiber was obtained in the same manner as in Example 1 except that the weight ratio of the acrylonitrile polymer and the barium sulfate fine particles was 100: 5. The properties of the obtained fiber are shown in Table 1.

[Example 4]
An acrylonitrile fiber was obtained in the same manner as in Example 1 except that the weight ratio of the acrylonitrile polymer and the barium sulfate fine particles was 100: 35. The properties of the obtained fiber are shown in Table 1.

[Example 5]
Acrylonitrile fiber was obtained in the same manner as in Example 1 except that the barium sulfate fine particles were changed to BF-25 (average particle diameter 0.03 μm, manufactured by Sakai Chemical Industry Co., Ltd.). The properties of the obtained fiber are shown in Table 1.

[Example 6]
Acrylonitrile fiber was obtained in the same manner as in Example 1 except that the barium sulfate fine particles were changed to B-30 (average particle size 0.3 μm, manufactured by Sakai Chemical Industry Co., Ltd.). The properties of the obtained fiber are shown in Table 1.

[Example 7]
Acrylonitrile fiber was obtained in the same manner as in Example 1 except that the fineness obtained was 1.7 dtex. The properties of the obtained fiber are shown in Table 1.

[Comparative Example 1]
Acrylonitrile fiber was obtained in the same manner as in Example 1 without adding barium sulfate fine particles. The properties of the obtained fiber are shown in Table 1.

[Comparative Example 2]
Spinning was carried out in the same manner as in Example 1 except that the weight ratio of the acrylonitrile polymer to the barium sulfate fine particles was 100: 40, and no fiber was obtained.

[Comparative Example 3]
Acrylonitrile fiber was obtained in the same manner as in Example 1 except that the barium sulfate fine particles were general-purpose precipitated barium sulfate BLANK FIXE (average particle size 0.7 μm, manufactured by Sakai Chemical Industry Co., Ltd.). The properties of the obtained fiber are shown in Table 1.

As shown in Table 1, in Examples 1 to 4, the amount of barium sulfate fine particles added to the acrylonitrile fiber was changed, and the radiation shielding performance increased as the amount of barium sulfate fine particles added increased. Further, it was confirmed that even when 35% barium sulfate fine particles were added, the tensile strength was 2.0 cN / dtex or more, and the fiber properties were not significantly impaired. In Examples 5 and 6, although the average particle diameter of the barium sulfate fine particles was changed within the range of the present invention, it was confirmed that the radiation shielding performance and the fiber physical properties were maintained. In Example 7, the fineness was set to 1.7 dtex, and the same result as in Example 1 was obtained.

On the other hand, in Comparative Example 1, acrylic fiber to which barium sulfate fine particles were not added was spun, but the radiation shielding performance was almost zero, and it can be seen that general acrylic fiber has no radiation shielding performance. In Comparative Example 2, the addition amount of the barium sulfate fine particles was increased, but the spinning dope gelled and nozzle breakage or thread breakage occurred, and good fibers could not be obtained. In Comparative Example 3, barium fine particles having a large average particle diameter were used, and although radiation shielding performance was obtained, the fiber physical properties were weak, so that subsequent processing was difficult and impractical. Further, in this example, although barium sulfate fine particles having the same weight as in Example 1 or 5 were contained, the average particle diameter of the barium sulfate fine particles was large, so that the radiation shielding rate was inferior.

Claims (6)

A radiation-shielding acrylonitrile-based fiber containing an acrylonitrile-based polymer and barium sulfate fine particles having an average particle diameter of 0.01 to 0.05 μm. The radiation shielding acrylonitrile fiber according to claim 1, wherein the content of the barium sulfate fine particles is 5 to 35 parts by weight with respect to 100 parts by weight of the acrylonitrile polymer. The radiation shielding acrylonitrile fiber according to claim 1 or 2, wherein the tensile strength is 2.0 to 3.5 cN / dtex. The radiation shielding acrylonitrile fiber according to any one of claims 1 to 3, wherein the fineness is 0.5 to 3.3 dtex. A fiber structure containing the radiation shielding acrylonitrile fiber according to any one of claims 1 to 4 .
A method for producing a radiation shielding acrylonitrile fiber containing an acrylonitrile polymer and barium sulfate fine particles having an average particle size of 0.01 to 0.5 μm, comprising an aqueous dispersion of barium sulfate fine particles in an acrylonitrile polymer solution A method for producing a radiation-shielding acrylonitrile-based fiber, comprising spinning a spinning dope obtained by mixing.