JPS61102411A - Production of rayon containing high concentration of barium sulfate - Google Patents

Abstract

PURPOSE:To obtain the titled rayon having improved X-ray shielding properties and high-density soundproofing effect in a stable spinning productivity, by adding highly concentrated dispersion of barium sulfate to a spinning stock solution of viscose, adjusting the stock solution to >= a specific value of cellulose concentration in the spinning stock solution and spinning it. CONSTITUTION:In adding dispersion of barium sulfate to a spinning stock solution of viscose rayon and spinning it, the dispersion of barium sulfate is made into 40-80wt%, preferably 50-70wt% high concentration, the cellulose concentration [cellulose/(water+alkali+cellose)X100] in the spinning stock solution of viscose except barium sulfate is adjusted at least to 7.0wt% and the spinning stock solution is spun.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing rayon containing barium sulfate at a high concentration, which has excellent X-ray shielding properties and high-density soundproofing effects.

Conventional technology>Ujiro's method is to remove recycled m-boxes containing barium sulfate.
For example, polynosic regeneration using viscose containing 2, s, 2 s, o% cellulose and 1.5 to 3.5% alkali and barium sulfate as described in Japanese Patent Publication No. 48-92622. There is a method for producing fibers, published in 1983.
Publication No. 17801 Jζ discloses a method in which a barium sulfate dispersion is prepared using hiscose for ordinary rayon and added to a stock solution of viscose at a concentration of 40% or less and 10% or more.

As is known in the art, the polynosic recycled knitting machine fibers require gradual coagulation and regeneration of viscose under stretching, resulting in slow spinning speeds and low productivity, as well as low cellulose content. When barium sulfate was added at a high rate, the spinnability was unsatisfactory as yarn breakage occurred. - Even in the case of a night shift adapted to the manufacturing method of ordinary rayon, which is different from polynosic in the low concentration range, if the concentration of the barium sulfate dispersion is 40% or less, it is not necessary to add it to the viscose spinning dope. In this case, the concentration of the cellulose component is inevitably low, so stable spinnability cannot be obtained, and the rate of decline in mechanical properties is large, making it impossible to obtain industrially satisfactory processability, especially for spinning filament yarns. .

<Problems to be solved by the invention> Barium sulfate not only shows excellent contrast properties in X41J fluoroscopy, but also has X-ray shielding and soundproofing effects due to its high specific gravity, but barium sulfate must be added and contained in a high concentration. Otherwise, it will not be able to perform its function. The present invention has been made through intensive studies to incorporate barium sulfate into rayon by adding and mixing it at a high concentration, and has discovered a manufacturing method that has stable spinning productivity that could not be obtained using conventional techniques.

Means for Solving the Problems> In general, fiber modifiers such as colorants and matting titanium compounds are added to viscose for ordinary rayon, and the resulting solution is often spun.

However, when a large amount of barium sulfate fine particles are added and mixed as in the present invention, the filtration of the dispersion medium of the dispersion becomes a concern that cannot be ignored, and it has been found that the cellulose concentration in the spinning dope is extremely important.

Normally, when spinning viscose for rayon, the viscose is spun through a nozzle in a Muller bath, and the viscose coagulates from the surface of the viscose flow when it comes into contact with the spinning bath. Cellulose xanthate in viscose becomes zinc xanthate due to Zn2+ in the Mueller bath, and xanthate is regenerated by lowering the pH due to sulfuric acid in the spinning bath. Afterwards, viscose is dehydrated and regenerated through the regenerated surface layer. The rate of coagulation and regeneration varies depending on the contents of cellulose, alkali, and water. In particular, the water content of cellulose has a large influence.

The present inventors investigated a method for industrially producing rayon containing a large amount of barium sulfate in the amount of 35% to 80Jl using commonly used viscose for ordinary rayon and a Mueller bath. As a result, a concentrated sol or slurry in which the barium sulfate dispersion is more than 4QWt% and less than 80ft% is suitable, and more preferably 5QWt% or less.
It has been found that Qwt% to 70wt% is suitable. Stable spinning productivity can be achieved by using concentrated barium sulfate and adjusting the cellulose concentration in the viscose spinning dope to be at least 7.0%, preferably 7.4% or more. It was found that

When the barium sulfate dispersion is 4Qwt% or less, the cellulose concentration should be 7.4vt% to 5% in order to make the barium sulfate contained in the cellulose 35% to 80% by weight.
．． It was diluted to 4% and stable spinning could not be obtained. In order to ensure stable spinnability, it is necessary to add barium sulfate dispersion to 40W (if the concentration is less than 30%, 30' to 30%
In fact, only 5% undropped product was obtained. However, when using a highly dispersible barium sulfate concentration of more than 4Qwt% and less than 8Qwt%, surprisingly stable spinnability can be obtained, and it is sufficient for pot winding cake removal of rayon filament. It has become possible to carry out the process stably, and it has become possible to obtain am containing barium sulfate in cellulose at a concentration of 35% by weight or more and up to 80% by weight.

When the barium sulfate dispersion exceeds 9 Qwt%, stable spinning was not possible because the slurry formed a dry surface layer, causing lumps and lumps like secondary agglomeration.

A dispersion of barium sulfate with a high temperature of 11 degrees cannot achieve its intended purpose unless it is wet re-pulverized if it is made into a powder, but it is preferable to use a dispersion that is adjusted without drying after forming fine particles. In particular, it was discovered that if the dispersion liquid is adjusted in advance to an alkali concentration of 4 to 10%, the process condition when cross-mixing is added to the viscose stock solution is extremely good.

If the concentration of cellulose in the spinning stock solution does not reach 7.0% even if this JUNA #IMrlI barium dispersion is used,
The spinning stability was insufficient, and the setting range for making the yarn denier thinner or thicker was limited, resulting in poor performance.

The above normal Muller is ii, 5o4s o~135
g/(1, Zn80410~20 g/l and Na28
0425 Q 〜36θy/I, temperature 4
The temperature is 0 to 50°C. What is ordinary rayon viscose?1
It has the following characteristics: a concentration of 250 to 3201 cellulose, 8 to 1O, alkali/cellulose 0.6 to 0.8, and a ball falling speed of 30 to 50 seconds.

This J”l viscose stock solution has an alkali concentration of 4 to 10%.
, barium sulfate 4 Q wt% higher than BQwt%, preferably 50 wc% to 7 Qwt%, after kneading, spinning in a Muller bath Iζ and coagulating and regenerating,
Rayon with a high barium sulfate content can be obtained by conventional scouring and drying.

Rayon yarn containing about 4 Qwt% of barium sulfate in the fiber width has a specific gravity of 2.0, and when a woven fabric is made with a layer weight of 400 g, the xN transmittance near the wavelength λ-2λ is less than 5%, and the wavelength λ-0,2λ
In the vicinity, the X@ transmittance is about 60% and a shielding effect can be obtained, and when it is contained in a higher concentration, the effect is further improved.

However, if the content exceeds 80%, the cellulose component constituting the fibers will be too small and the strength will drop sharply, so 80% by weight is the upper limit. On the other hand, when evaluating surgical gauze for contrast imaging, the barium sulfate content was 30%.
If it is less than 35%, it is unclear, so it is clear that at least 35% is necessary, and in terms of functionality, 35% or more, 80
An appropriate content was less than % by weight.

The barium sulfate used in the present invention has a particle size of 1 μm or less, preferably 7 μm or less, and if necessary, pigments and other additives may be mixed therein.

Example> Example 1 Viscose prepared by adding and kneading alkali-concentrated [6% barium sulfate 55wt% water dispersion] to viscose containing 8% cellulose and 6% alkali, nozzle hole diameter 0.07, number of holes 30
h2504130t/l, '1a
dO215Q/l, Na281J4300 Q/l-1
The material was spun in a spinning bath at 46° C., passed through a 15% draft, and then wound up into a cake using a pot-type winding machine.

Then, the conventional method of scouring and drying was carried out. For the removal of barium sulfate, 4 types of fibers were prepared, each containing 41% SO by weight, 66% by weight of N, and 80% by weight. On the other hand, for comparison, the alkali concentration was 6%.
A 35 wt % aqueous dispersion of barium sulfate was spun in the same manner as A. When barium sulfate was dispersed at a high concentration, the spinning condition was stable, and when the cellulose concentration was 74% or more, particularly good results were obtained. In the case of -35 W[%, when aiming for a high barium sulfate content, the spinning condition worsened and a good barium sulfate-containing rayon yarn could not be obtained. The rayon-based strip with a content of 41% by weight obtained using a barium sulfate 66wt% dispersion had a strength of 0.90 Q/'d and an elongation of 26.
%, 167 denier, 30 filaments were obtained, and the gold thread was further twisted to produce a 2/2-thin, 400 g/rye fabric. The X-ray transmittance of the cloth with 6 NV, 2 mA tungsten anticathode as the X-ray source and TO, cm #jl from the XH source is 97% lower than that without cloth, and the transmittance is 3%.
It had an X-ray shielding effect.

Example 2 Cellulose 8.6% Alkaline 6.2% Hiscose.

Barium sulfate with alkali concentration 6% (average particle size 06μ)
11 wt% water dispersion was added continuously, and the viscose mixed with a line mixer was passed through a nozzle with a nozzle diameter of 0.10 mm and 30 holes to form H4SO4135Q.
/l, Zn80412 Q/l, Na25(J4
330 g/1.1111 Spun into a spinning bath at 45°C,
It was rolled up into a cake shape using a pot-type winding cannon, and then scoured and dried using the usual method. In this case, stable spinning is possible with a barium sulfate concentration of up to 75M concentration in rayon, and 8
Although some of the 0-layer yarns had poor unwinding properties during scouring and drying, yarns could be obtained. The cellulose content in viscose Igd after any addition was found to be 7.0% or more (relative to the total excluding barium sulfate). On the other hand, as a comparative example, powdered barium sulfate (average particle size 1.8μ) was mixed with water to adjust the dispersion number of alkali-free water of 3QIft%, and was added continuously in the same way to conduct a 4Fi system test. 1;. Stable spinning was possible only at a barium sulfate concentration of about 30% by weight contained in rayon.

Claims (1)

[Claims] 1) When producing rayon containing barium sulfate at a high concentration of 35% to 80% by weight in the fiber by adding and mixing a barium sulfate dispersion to a viscose spinning dope,
The barium sulfate dispersion has a high concentration of more than 40 wt% and 80 wt% or less, preferably 50 wt% to 70 wt%,
Cellulose concentration in the viscose spinning stock solution excluding barium sulfate [cellulose concentration = cellulose / (water + alkali +
1. A method for producing rayon containing a high concentration of barium sulfate, the method comprising spinning rayon with a content of cellulose (cellulose) x 100 of at least 7.0%. 2) The method for producing rayon containing a high concentration of barium sulfate according to item 1, which comprises dispersing barium sulfate in advance in an aqueous solution having an alkaline concentration of 4 to 10%, and then adding and kneading it to the viscose spinning dope. . 3) The barium sulfate particles have a particle size of 1 μm or less,
2. The method for producing rayon containing a high concentration of barium sulfate according to item 1, wherein the rayon is added to the viscose stock solution without drying after forming the fine particles.