WO2018088982A1

WO2018088982A1 - X-ray protective textile material comprising nano metal particles

Info

Publication number: WO2018088982A1
Application number: PCT/TR2017/050543
Authority: WO
Inventors: Fatma Banu NERGIS; Cevza CANDAN; Nebahat Aral YILMAZ; Ismail Duman
Original assignee: Istanbul Teknik Universitesi
Priority date: 2016-11-11
Filing date: 2017-11-02
Publication date: 2018-05-17
Also published as: TR201616253A1

Abstract

The invention is related to a radiopaque particle and polymer mixture that has been developed for protection against x-rays to be used in textile materials. Mentioned mixture can be used primarily in the medical field and additionally in all fields that utilize x-rays.

Description

DESCRI PTI ON

X- RAY PROTECTI VE TEXTI LE MATERI AL COMPRI SI NG NANO METAL PARTI CLES

Technical Field of the I nvention

The invention is related to a radiopaque particle and polymer mixture that has been developed as protection against x-rays to be used in textile materials. Said m ixture can be used primarily in the medical field, and additionally in all fields that utilize x-rays.

Background of the I nvention (Prior Art)

For X-ray shielding purposes, apron-like, sewn products are currently used in the market. These products are generally composed of layers. The inner layer is a plate made of lead particles added to a polymer (e.g. vinyl) whereas the upper layer is a nylon , polyester, etc. woven fabric. Likewise, alternative products having inner layers from tungsten, bismuth , tin , antimony are commercially offered. Thin inner layers of polymer and metal powder additives can deform during use, let alone being so rigid and heavy that they not only prevent the mobility of user to a great extent, but also they may cause severe health problems related with back, lower back and/or spine when prolonged wearing in operation rooms, for example, is involved.

Moreover, cracks/fractures in the inner (i .e. protective) layer of an apron -which can only be detected by taking X-ray images of the apron- can occur in due course, even if there is no deformation and/or flaw visible with naked eye in the fabric clothed the inner layer. Radiation can easily pass through such cracks/fractures, which results in weakened x-ray attenuation performance of the apron . Depending on the severity of the cracks/fractures in an inner layer, the protection level expected from an apron may not be attained at all. This issue in particular raises a question regarding the useful econom ic life of commercial x-ray protective aprons.

Finally, although lead is the most frequently used material to protect against x-rays, it is crucial to develop products that comprise lim ited amount of lead or preferably leadfree compounds simply because lead is the second most health-endangering as well as environmentally hazardous material (ATSDR, 201 5) in the world, following arsenic. Consequently, there are some products developed by taking the points outlined above.

Some of the patents of the known state of the art are as follows:

The TR 201407402 B numbered patent describes an elastic material that protects against ionized radiation . I t is stated that the materials, that are formed by adding, metals of different densities and Sn , SnO, BaO, BaS0₄, W, W₂0₃, Wl ₃, WC, Bi, Bi₂0₃, Bi l O, Bi l ₃, bism uth subnitrate, bism uth subcarbonate into polymer and then further adding wool fiber, have protection against x-rays.

I n the patent numbered GB 954,594 a product is described wherein a small amount of wool has been added for reinforcement and lead particles have been added to the matrix instead of using a lead sheet.

I n the patent document numbered US 2002/0148980 A1 bismuth oxide and barium sulfate has been added into low density polyethylene in order to weaken the scattered x- rays. I t is defined that the 100 keV primary x-ray is weakened by 10-50% by this product.

I n the patent numbered US 7,897,949 B2 it has been shown that at least one of tin , antimony, iodine, caesium , barium , lanthanum , cerium , praseodymium and neodym ium can be chosen as a low atom numbered material. Elements which are rare, such as samarium , gladolinium , terbium and erbium can be mixed with the above mentioned elements. I t is noted that each of the composite plates from the patented products were equivalent to 0, 125m m lead and when 4 composite layers were combined, it has been noted that 0,5mm lead equivalency can be provided.

The patent document numbered US 2005/0121631 is based on form ing fine composite layers by adding metal particles into latex (such as, acrylic, styrene/butadiene, vinyl, acetate/ acrylic acid copolymers, vinyl acetate or urethane) .

I n the patent numbered US 5,548, 125 a material that is protective against radiation was proposed by adding tungsten into natural rubber, and in the patent numbered US 2004/0262546 again rubber and Bi₂0₃, W₂0₃, SnO, SnSb0₂ additives were used to form mixtures that could weaken the effect of x-rays. Present academic studies and patents do not focus on the parameters that would influence wearing comfort and life time of the products developed. Within the invention, the aim has been to form materials, that contain a woven substrate and a composite structure with radiopaque additives applied to the substrate, for protective clothing having high wearing comfort and resistance to mechanical deformations.

The developed coated fabrics shall be examined for their bending resistance together with the protection against x-rays features. The results of the tests that have been carried out show that the developed fabrics not only provide protection equivalent to lead but also are resistant against repeated bending.

By this means, a material reinforced with a textile structure will have been developed that will have protective properties, and that will not have problems such as cracking or breakage during usage.

Brief Description of the I nvention and its Aims

Prototypes of textile based x-ray shielding composite materials with m icro and nano sized radiopaque powder additives using powder metallurgy knowledge and technology are described within the invention .

Development of x-ray shielding materials that are sewable, convertible to garment form and compatible with the body movements is maintained. Therefore, people who has to wear uncomfortable lead aprons during radiological diagnosis, operations and therapy applications will use products that will ease their movement and make them feel comfortable.

Safety problems (i.e. high radiation dosage intake) due to the cracked, broken protective layers, repairing costs and costs arising because of the unusable state of the protective garments will be reduced.

By the use of nano sized additives lighter products can be obtained that yield the desired lead equivalent protection (for example; 0,25m m Pb, 0,50 mm Pb) By this means, problems such as chronic backbone, lowerback and back pain faced by medical staff will be relieved. • The material developed by means of the invention comprises radiopaque materials having low toxicity such as tungsten , bismuth , tin etc. , and is used to manufacture products that do not threaten human health and that are environmentally friendly.

• Heavy weight problem is elim inated due to the use of nano sized particles in the production of wearable fabric garments.

Detailed Descript ion of the I nvent ion

Single side coated and/or both sides coated fabric structure is maintained by using powder- polymer mixture and suitable coating techniques subject to the invention . The polymer (coating material) that is used has high viscosity that can carry heavy metal particles and it has an elastic structure that is chem ically compatible with the fabric on which it is applied. Silicone rubber or other sim ilar coating materials that yield the mentioned performance are used to obtain the radiopaque powder-polymer m ixture. I n the invention , silicon rubber in liquid form that can be preferably applied to textile surfaces is used.

Materials that have high ability of weakening x-rays such as tungsten , bismuth , tin , antimony, barium and various other compounds thereof are used as radiopaque particles. Tungsten , bismuth , tin, copper and barium sulfate powder has been used in the studies.

I n the invention , conventional textile surfaces (woven, knitted and nonwoven) that have been produced from natural, synthetic and/or regenerated fibers are used as substrates. 1 00% cotton , woven plain fabric has been used in the material developed.

Materials that provide the desired lead equivalent protection can be obtained by mixing radiopaque particles and polymer at various ratios. Radiopaque powder volume ratios of different samples are presented in Table 1 (W: Tungsten , Sn : Tin , Cu : Copper, Bi : Bism uth) . Silicon rubber in liquid form is used in the study. Commercial silicon rubber in liquid form is purchased as ready-made product and it is then prepared according to the process which comprises the steps of preparation of said m ixture for which the ratios of usage of the a and b components of the rubber material that comprises the a and b components separately is described. The coating mixture is prepared using radiopaque particle and silicon rubber such that the ratio by weight of the radiopaque particle constitutes at least 60% of the mixture. This mixture is mixed in a mechanical mixer for a duration of 30 minutes to 1 hour and following this, in order to prevent the problem of air bubbles the mixture is vacuumed for 30 minutes up to 1 hour.. I n the next step, the mixture is applied to one side and/or both sides of the fabric by means of a knife coater. Following the coating process for curing the silicon rubber, the coated fabrics are kept in an ovenat 90-1 10^s C for 1 5-25 minutes.

Table 1 . Characteristics of the samples

As a result of the measurements carried out at 1 00 kV for the samples given in Table 1 , the coating thicknesses and weights required for 90% and 95% protection are presented in Table 2. The lead thickness that is required for shielding 90% of the x-rays in the measurements carried out at 100 kV tube voltage is 0,35 mm , while the lead thickness for shielding 95% of the x-rays is 0,5 mm . Therefore, it is possible to say that the samples with the attenuation ratio of 90% have the lead equivalent thickness of 0.35 m m Pb and the samples with the attenuation ratio of 95% have the lead equivalent thickness of 0.50 mm Pb. Table 2. Average thickness and weight values of the samples

(The thickness and weight measurements do not include fabric thickness and weight.)

Higher percentage of powder additive in the coating gives rise to the formation of thinner and lighter structures that provide sim ilar protection levels. Among all the samples that provide 90% protection at 100 kV, the sample that has the thinnest coating with a thickness of 0,69 mm is the one that contains 20 % tungsten by volume (i .e. sample N3) . The corresponding weight of this sample is 3232,62 g/m².

The radiopaque particle sizes in the examples given in Table 1 and Table 2 are micron sized and studies with nano sized tungsten particles have also been conducted. I n Table 3 the coating material comprising the same volume ratio of ( 12% ) tungsten and the average particle size of each sample has been given.

Table 3. Samples having micro and nano sized particles

I t has been observed that the samples having nano sized particles have higher radiation attenuation values. Moreover, equivalent protection levels are attained at lower thickness and weight values when nano sized particles are used. Accordingly, for the samples comprising 150 nm tungsten particles with a volumetric ratio of approximately 12% , coating weight of 2836,20 g/m2 has been sufficient for 90% protection at 1 00kV (Table 4) .

Table 4. Thickness and weight values of samples with micro and nano sized particles

Wearable material that has protection against x-rays can be used for medical diagnostic and treatment applications, (for example radiology, fluoroscopy, radiotherapy etc.) and in other fields (for example non-destructive testing and analysis of materials) that utilize x-rays.

Claims

CLAI MS

1 . A method of coating a fabric with a textile material comprising nano particles that are protective against x-rays characterized in that it comprises the steps of ;

- Preparing silicon rubber in liquid form ,

Preparing a coating mixture with radiopaque particles and silicon rubber such that the ratio of the radiopaque particle by weight of the mixture is 60% ,

Mixing this mixture in a mechanical mixer for a period of 30 minutes to 1 hour,

Following this, vacuuming the mixture for 30 minutes to 1 hour in order to prevent air bubble problem,

Applying the mixture with a knife coater to single side and/or both sides of the fabrics, Following the coating process, keeping the coated fabrics in an oven for 1 5-25 minutes at temperatures between 90-1 10^s C in order to cure the silicon rubber.

2. A method according to claim 1 , wherein the vacuum pressure is at least -0,8 bars.

3. A method according to claim 1 , wherein the radiopaque powder comprises at least one of tungsten, bismuth, tin, copper and barium sulfate particles.

4. A method according to claim 1 , wherein the fabric is a woven or knitted or nonwoven fabric.

5. A method according to claim 1 , wherein the fabric is made of 100% cotton, plain weave fabric.

6. A textile material comprising nano particles protective against x-rays used in the method of claim 1 .

7. A textile material according to claim 6, wherein it comprises silicon rubber in liquid form and nano sized radiopaque particles.

8. Usage of a textile material according to claim 6, in the medical field for diagnostic and treatment purposes.

9. Usage of a textile material according to claim 6, during medical procedures such as radiography, fluoroscopy, and radiotherapy.

1 0. Usage of a textile material according to claim 6, in fields utilizing x-rays.

1 1 . Usage of a textile material according to claim 6, in the non-destructive analysis and testing of materials.