FIELD OF THE INVENTION
[0001] The present invention relates to a radio frequency blocking composition and a method for preparing the same. The present invention also relates to a wash-durable textile fabric comprising the radio frequency blocking composition and a method for preparing the same.
DESCRIPTION OF THE PRIOR ART
[0002] Communication means such as phones, cordless, mobiles, 3G network, and Wi-Fi are
a big leap in the telecommunications field. As a result people across different places are coming
closer and closer. However, the use of these communication devices has a major drawback which
is its negative impact on the health of human beings.
[0003] An average cell phone transmission is 1-2 watts of power in the frequency range of
824-849MHZ (CDMA), 890-915MHz (GSM900) and 1710-1780 MHz (GSM1800). An average cell
tower antenna transmission is 869-894MHz (CDMA), 935-960MHz (GSM900), and 1810-
1880MHz (GSM1800). 3G frequency range falls between 2110-2170 MHz and is much higher than
normal cell phone or cell tower transmissions.
[0004] A cell phone has a specific absorption rate (SAR) which is a measure of the amount of
radio frequency energy absorbed by the body when using a mobile phone. The federal
communications commission (FCC) has certain safety guidelines based on the SAR. The safe SAR
limit is 1.6W/kg corresponding to 6 minutes/day usage with a margin of 3-4 minutes which makes
the time limit 18-24 minutes/day.
[0005] Regardless of the SAR limit an average person uses a cell phone for more than 18-24
minutes/day, sometimes also for hours at a stretch. Besides this, a person is also exposed to
radiations generated from cell tower antennas.

[0006] These radio frequency (RF) waves/radiations are very harmful in nature as they adversely affect human skin and have harmful effects on the cells of the human body. Excess exposure to such radiations can have adverse effects on human health. It can cause abnormal cell growth, DNA damage, reduced immunity, weakened blood brain barrier, leukemia, infertility and miscarriage, chronic fatigue and hearing and cardiac problems.
[0007] Attempts have been made to solve some of the above problems resulting in creation of protective fabrics that could shield or block harmful radio frequency (RF) if not completely, then at least to a level that is safer than at present.
[0008] In the past, protective fabrics covered the source of RF emissions. This concept was further developed to making certain zones completely RF free by blocking RF emissions by creating an interference generating pattern (IGP). However, this the concept has limitations because it is confined to places and it vicinity where a given source is located. [0009] Then came the concept of wearable fabrics having metal yarn present in it for protecting human beings from RF radiations. The metal yarn used were silver (Ag) and copper (Cu) which also showed anti-bacterial property. But usage of these metal yarns also have their own drawbacks, for example silver was not practically feasible because the following reasons-silver is a precious metal and very expensive, silver (Ag) cannot be washed often, the fabric becomes too heavy if the concentration of silver (Ag) is more, etc. Additionally, including silver and copper resulted in the fabric becoming glossy and also caused itching to wearer. [0010] Further, complete blocking of RF waves is not always practical, particularly if one is expecting to receive important communication messages or calls and is wearing a mobile device on his person for this purpose. However, there is a need for a protective fabric/clothing that can

block a large percentage of the harmful RF waves, yet allowing a small percentage to reach the mobile device so as to permit reception of communication.
[0011] Thus, there is an imminent need for creating a fabric that overcomes at least some of the above mentioned problems and yet provides comfort, antimicrobial properties, no itching and can sustain multiple fabric washings without losing its RF blocking ability.
OBJECTS OF THE INVENTION
[0012] An object of the present invention is to provide a composition which blocks radio
frequency waves, which can be applied to textile fabrics to provide health benefits to the wearer.
[0013] Another object of the present invention is to provide a method for preparing a
composition which blocks radio frequency waves, and a method by which it can be applied to
textile fabrics to provide health benefits to the wearer without losing its RF blocking ability after
repeated washing.
SUMMARY OF THE INVENTION
[0014] Accordingly in an aspect of the present invention a radio frequency blocking
composition is disclosed that comprised of a suspension of silver nanoparticles and copper
nanoparticles mixed with water wherein the silver nanoparticles are present in a concentration
of 150 to 450 gms/litre and the copper nanoparticles are present in a concentration of 10 to 25
gms/litre.
[0015] According to another aspect of the present invention a wash-durable textile fabric is
disclosed that comprised of a radio frequency blocking composition wherein the composition
comprises a suspension of silver nanoparticles and copper nanoparticles fixed into the fabric by

a resin, the silver nanoparticles being present in a concentration of 150 to 450 gms/litre and the
copper nanoparticles are present in a concentration of 10 to 25 gms/litre.
[0016] According to some embodiments, the resin is formaldehyde based dimethylol
dihydroxyethyleneurea, diethylene glycol based resin or glyoxal based resin free from
formaldehyde.
[0017] According to some embodiments of the present invention, pH of the composition is
5.5 to 6.5.
[0018] According to another aspect of the present invention a method for preparing a radio
frequency blocking composition is disclosed that comprises of the steps of suspending silver
nanoparticles in an aqueous solution of nitric acid to yield silver nitrate salt suspension to which
water is added; adding copper nanoparticles to the silver nitrate salt suspension and mixing the
same to yield the radio frequency blocking composition wherein the silver nanoparticles are
present in a concentration of 150 to 450 gms/litre and the copper nanoparticles are present in a
concentration of 10 to 25 gms/litre.
[0019] According to yet another aspect of the present invention a method for preparing a
wash-durable textile fabric is disclosed that comprised of a radio frequency blocking composition
comprising the steps suspending silver nanoparticles in an aqueous solution of nitric acid to yield
silver nitrate salt suspension to which water is added; adding copper nanoparticles to the silver
nitrate salt suspension and mixing the same to yield the radio frequency blocking composition,
adjusting the pH of the solution to 5.5 to 6.5 and mixing the resultant solution; soaking a textile
fabric in the above solution for at least 30 mins followed by drying the fabric; fixing the
nanoparticles in the fabric by coating the fabric with a resin; and curing the fabric at 150 to 165°

C for at least 8 minutes to fix the resin to the fabric, wherein the silver nanoparticles are present in a concentration of 150 to 450 gms/litre and the copper nanoparticles are present in a concentration of 10 to 25 gms/litre.
[0020] According to some embodiments of the present invention, the resin is formaldehyde based dimethylol dihydroxyethyleneurea, diethylene glycol based resin or glyoxal based resin free from formaldehyde.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0021] According to an embodiment of the invention, there is provided a radio frequency blocking composition comprising a suspension of silver nanoparticles and copper nanoparticles mixed with water wherein the silver nanoparticles are present in a concentration of 150 to 450 gms/litre and the copper nanoparticles are present in a concentration of 10 to 25 gms/litre. [0022] According to another embodiment of the invention, there is provided a wash-durable textile fabric comprising a radio frequency blocking composition wherein the composition comprises a suspension of silver nanoparticles and copper nanoparticles fixed into the fabric by a resin, the silver nanoparticles being present in a concentration of 150 to 450 gms/litre and the copper nanoparticles are present in a concentration of 10 to 25 gms/litre. [0023] According to a further embodiment of the invention, there is provided a method for preparing a radio frequency blocking composition comprising the following steps:
a. suspending silver nanoparticles in an aqueous solution of nitric acid to yield silver nitrate
salt suspension to which water is added;
b. adding copper nanoparticles to the silver nitrate salt suspension and mixing the same to
yield the radio frequency blocking composition wherein the silver nanoparticles are present

in a concentration of 150 to 450 gms/litre and the copper nanoparticles are present in a
concentration of 10 to 25 gms/litre. [0024] According to yet another embodiment of the invention, there is provided a method for preparing a wash-durable textile fabric comprising a radio frequency blocking composition comprising the following steps:
a. suspending silver nanoparticles in an aqueous solution of nitric acid to yield silver nitrate
salt suspension to which water is added;
b. adding copper nanoparticles to the silver nitrate salt suspension and mixing the same to
yield the radio frequency blocking composition;
c. adjusting the pH of the solution to 5.5 to 6.5 and mixing the resultant solution;
d. soaking a textile fabric in the above solution for at least 30 mins followed by drying the
fabric;
e. fixing the nanoparticles in the fabric by coating the fabric with a resin; and
f. curing the fabric at 150 to 165° C for at least 8 to 12 minutes to fix the resin to the fabric,
wherein the silver nanoparticles are present in a concentration of 150 to 450 gms/litre and
the copper nanoparticles are present in a concentration of 10 to 25 gms/litre.
[0025] The resin used can be formaldehyde based dimethylol dihydroxyethyleneurea, diethylene glycol based resin or glyoxal based resin free from formaldehyde. Preferably, the pH of the composition is close to the pH of human skin i.e. in the range of 5.5 to 6.5. The pH of the composition can be adjusted using acetic acid.
[0026] Preferably, the copper nanoparticles are present in a concentration range of 10 to 25 gms/litre in the composition while the silver nanoparticles suspension are present in a

concentration range of 150 to 450 gms/litre. The resin used is in a concentration of about 150 to 325 gms/litre of total chemical composition made. The resin is in a liquid form. The silver and copper nanoparticles are about 30-40nm in size and due to their small particle size, they can easily travel deep into the textile fabric reaching the fibre level and get embedded and fixed into the fabric by use of the resin. Use of the resin for fixing the nanoparticles into the fabric allows for 80% RF blocking ability of the fabric even after 30 washes. However, RF blocking ability of the fabric is about 60% after 30 washes if resin is not used as some percentage of the RF blocking ability of the fabric is lost due to repeated washing.
[0027] After curing the textile fabric, optionally, silicon spraying can be done for getting a softer and smoother finish for the fabric. 3% micro amino silicon is sprayed on the fabric. The smoothness is due to the affinity of the amino groups to the fibres, which promotes optimum orientation of the silicon on the substrate, thus giving an ideal soft feel.
[0028] RF protective fabric could be used for making garments like bottoms, shirt, socks, T-shirts, cap, curtains, and electronic gadget covers etc. In yet another embodiment of the present invention the RF waves blocking composition may also be mixed with paints and applied separately to homes or vehicles for protecting the same from the harmful effects of RF waves. [0029] The following experimental examples are illustrative of the invention but not limitative of the scope thereof: Example 1
[0030] Table 1 shows the amounts of the various constituents used to prepare the radio frequency blocking composition. Copper nanoparticles were not added to prepare the composition, as is shown in the Table 1. A textile fabric was then soaked in the composition for

30 minutes at a pH of 5.5-6.5 adjusted using acetic acid. The composition was then fixed into the textile fabric using the resin specified in Table 1 and thereafter the fabric was cured at 150° C for 8 minutes followed by spray coating with 3% micro amino silicon. Table 1:

Constituents Concentration
Copper nanoparticles 0 gms/litre
Suspension of silver nanoparticles 450 gms/litre
Resin dimethylol dihydroxyethyleneurea 325 gms/litre
Resin Catalyst MgCb 3.2 gms/litre
[0031] A frequency generator was then used to generate radio frequencies on one side of the fabric and an acoustimeter was used to measure the frequency transmitted through the fabric on the other side of the fabric. It was found that the radio frequency blocking ability of the fabric was only 30%. However, the antimicrobial properties of the fabric were retained as was evidenced by antimicrobial testing performed as given below:
[0032] The base protocol used for assessing antimicrobial activity of the fabric was the JIS rapid screen test. Microorganisms used for this test were Staphylococcus aureus and Klebsiella pneumonia. Phosphate buffer at pH 7.4 was used in the bacterial culture medium. A Square swatch of test fabric 5X5 cm was placed on the agar plate after treatment with a wetting agent. Onto this a known concentration of the bacteria inoculum (~102CFU/ml) was spread using a pipette. The value of bacteria inoculum placed was determined by the turbidity method. The agar plates with the specimen were then incubated for 24 hrs at a temperature of 37°C.

The number of bacterial colonies on the specimen were counted. The sample was removed from the Agar plate and checked for any bacterial growth under the sample touching the agar plate and also on the agar plate where the sample was sitting earlier. The total count is sum of the bacterial count on both sides of the specimen and the agar plate. The initial known bacterial count of the culture which was inoculated into the specimen and determined by the turbidity method was taken as the 0 hr reading. The reading obtained after 24 hrs was taken as 24 hrs reading. The reduction % in CFU/ml was calculated using the formula:
{CFU/ml(0hr)-CFU/ml(24 hr)}/CFU/ml(0 hr) X 100. An efficacy % of over 90% was considered satisfactory. Example 2
[0033] Table 2 shows the amounts of the various constituents used to prepare the radio frequency blocking composition. Silver nanoparticles were not added to prepare the composition, as is shown in the Table 2. A textile fabric was then soaked in the composition for 45 minutes at a pH of 5.5-6.5 adjusted using acetic acid. The composition was then fixed into the textile fabric using the resin specified in Table 2 and thereafter the fabric was cured at 165° C for 8 minutes followed by spray coating with 3% micro amino silicon.
Table 2:

Constituents Concentration
Copper nanoparticles 25 gms/litre
Suspension of silver nanoparticles 0 gms/litre
Resin dihydroxyethyleneurea 325 gms/litre
Resin Catalyst MgCl2 3.2 gms/litre

[0034] A frequency generator was then used to generate radio frequencies on one side of the fabric and an acoustimeter was used to measure the frequency transmitted through the fabric on the other side of the fabric. It was found that the radio frequency blocking ability of the fabric was only 50%. However, the antimicrobial properties of the fabric, as assessed by the JIS rapid screen test elaborated in Example 1, were found to be satisfactory. Example 3
[0035] Table 3 shows the amounts of the various constituents used to prepare the radio frequency blocking composition. A textile fabric was then soaked in the composition for 30 minutes at a pH of 5.5-6.5 adjusted using acetic acid. No resin was used to fix the composition into the textile fabric. The fabric was cured at 150° C for 15 minutes followed by spray coating with 3% micro amino silicon.
Table 3:

Constituents Concentration
Copper nanoparticles 25 gms/litre
Suspension of silver nanoparticles 450 gms/litre
[0036] A frequency generator was then used to generate radio frequencies on one side of the fabric and an acoustimeter was used to measure the frequency transmitted through the fabric on the other side of the fabric. It was found that the radio frequency blocking ability of the fabric was 90%. However, the antimicrobial properties of the fabric, as assessed by the JIS rapid screen test elaborated in Example 1, were found to be satisfactory. The wash-durability of the fabric was tested to see if it retains its radio frequency blocking ability after repeated washing. The radio frequency blocking ability of the fabric was found to be 60% after 30 washes.

Example 4
[0037] Table 4 shows the amounts of the various constituents used to prepare the radio frequency blocking composition. A textile fabric was then soaked in the composition for 30 minutes at a pH of 5.5-6.5 adjusted using acetic acid. No resin was used to fix the composition into the textile fabric. The composition was then fixed into the textile fabric using the resin specified in Table 5 and thereafter the fabric was cured at 150° C for 8 minutes followed by spray coating with 3% micro amino silicon.
Table 4:

Constituents Concentration
Copper nanoparticles 20 gms/litre
Suspension of silver nanoparticles 250 gms/litre
Resin dihydroxyethyleneurea 200 gms/litre
Resin Catalyst MgCb 2 gms/litre
[0038] A frequency generator was then used to generate radio frequencies on one side of the fabric and an acoustimeter was used to measure the frequency transmitted through the fabric on the other side of the fabric. It was found that the radio frequency blocking ability of the fabric was 90%. However, the antimicrobial properties of the fabric, as assessed by the JIS rapid screen test elaborated in Example 1, were found to be satisfactory.
[0039] The wash-durability of the fabric was tested to see if it retains its radio frequency
blocking ability after repeated washing. The radio frequency blocking ability of the fabric was found to be 80% after 30 washes.

Example 5
[0040] Four pairs of jeans, three of which is stitched using the fabric of Example 4 and the fourth being stitched from a normal untreated fabric, are tested for RF blocking ability. The untreated jeans sample is used as a control for the test. 1000 MHz of RF waves generated by a frequency generator are used to irradiate the three test samples and the control sample. An acoustimeter, used in the measurement of RF radiations, is used to measure frequency transmitted through the fabrics. The readings are taken considering two parameters. One set of readings is measured for the radiations outside the fabric (as generated by the frequency generator) and one set of readings, taken in five replicates, is measured to determine the RF radiation transmitted through the pockets of the jeans. Accordingly, percentage efficacy of the treated fabric in blocking RF radiations over untreated fabric was calculated. Table 6 shows the efficacy results of the RF protective fabric prepared as per the process of Example 5 when exposed to a range of RF radiations. Table 5:

Samples RF protection efficacy Remarks
Outside the fabric(MHz) In the folds of the fabric % Efficacy
Jeans-Untreated 980 978 976 973 972 970 ~0% NoRF protection
Jeans 1-treated 916 71 74 72 73 74 92.05% Good protection
Jeans 2-treated 920 82 84 79 83 80 91.13% Good protection
Jeans 3-treated 918 89 87 89 89 89 90.35% Good protection
Average of treated =90.53% Good protection

[0041] The results of Table 5 clearly show that the RF radiations for untreated jeans sample outside the fabric is 980MHz whereas inside the folds is 978, 976, 973, 972 and 970 MHz respectively. Thus an untreated fabric provides no protection from RF radiation. However, treated jeans sample 1 showed a 92.05% blocking of RF radiation within the pockets of the jeans. Treated jeans sample 2 showed a 91.13% blocking of RF radiation within the pockets of the jeans. Treated jeans sample 3 showed a 90.35% blocking of RF radiation within the pockets of the jeans. It is clear from Table 5 that the treated jeans samples provide a very high degree of protection against RF radiations as compared to the untreated jeans sample. Along with the property of RF protection the nanoparticles of silver and copper used also show anti-microbial activity which helps in maintaining the fabric free from microbes which tend to usually cause odour or staining in fabrics. Also, the antimicrobial properties of the fabric, as assessed by the JIS rapid screen test elaborated in Example 1, were found to be satisfactory.
[0042] From the foregoing examples, some advantages of RF protective fabrics can be enumerated as follows:
(a) The RF blocking fabric of the present invention protects a wearer from the harmful RF emissions that cause many health concerns.
(b) The RF blocking fabric of the present invention also helps to shield a wearer from the RF emissions from mobile phones kept in the folds of the fabric or in pockets of the fabric.
(c) The RF blocking fabric of the present invention is made up of Ag and Cu nanoparticles which exhibit antimicrobial activity. The nanoparticles thus help in prevention of odour and staining of clothes which occurs due to microbes. The fabric is thus more hygienic.

(d) The Ag and Cu nanoparticles in the RF blocking fabric are fixed with the resin and so as to allow for wash-durability i.e. the fabric can withstand at least 30 washes without any significant loss in RF blocking ability.
(e) The pH adjustment to 5.5-6.5 in the RF blocking fabric makes the fabric non-itchy and comfortable for the wearer.
(f) The silicon spray coating gives a smooth feel making the RF blocking fabric more comfortable to wear.
The above examples are non-limiting. The invention is defined by the claims that follow.

We Claim:
1. A radio frequency blocking composition comprising a suspension of silver nanoparticles and copper nanoparticles mixed with water wherein the silver nanoparticles are present in a concentration of 150 to 450 gms/litre and the copper nanoparticles are present in a concentration of 10 to 25 gms/litre.
2. A wash-durable textile fabric comprising a radio frequency blocking composition wherein the composition comprises a suspension of silver nanoparticles and copper nanoparticles fixed into the fabric by a resin, the silver nanoparticles being present in a concentration of 150 to 450 gms/litre and the copper nanoparticles being present in a concentration of 10 to 25 gms/litre.
3. The fabric as claimed in claim 2 wherein the resin is formaldehyde based dimethylol dihydroxyethyleneurea, diethylene glycol based resin or glyoxal based resin free from formaldehyde.
4. The fabric as claimed in claim 2 wherein the pH of the composition is 5.5 to 6.5.
5. A method for preparing a radio frequency blocking composition comprising the following steps:
a. suspending silver nanoparticles in an aqueous solution of nitric acid to yield silver nitrate
salt suspension to which water is added;
b. adding copper nanoparticles to the silver nitrate salt suspension and mixing the same to
yield the radio frequency blocking composition
wherein the silver nanoparticles are present in a concentration of 150 to 450 gms/litre and the copper nanoparticles are present in a concentration of 10 to 25 gms/litre.

6. A method for preparing a wash-durable textile fabric comprising a radio frequency blocking
composition comprising the following steps:
a. suspending silver nanoparticles in an aqueous solution of nitric acid to yield silver nitrate
salt suspension to which water is added;
b. adding copper nanoparticles to the silver nitrate salt suspension and mixing the same to
yield the radio frequency blocking composition
c. adjusting the pH of the solution to 5.5 to 6.5 and mixing the resultant solution;
d. soaking a textile fabric in the above solution for at least 30 mins followed by drying the
fabric;
e. fixing the nanoparticles in the fabric by coating the fabric with a resin; and
f. curing the fabric at 150 to 165° C for at least 8 to 12 min minutes to fix the resin to the
fabric,
wherein the silver nanoparticles are present in a concentration of 150 to 450 gms/litre and the copper nanoparticles are present in a concentration of 10 to 25 gms/litre.
7. The method as claimed in claim 6 wherein the resin is formaldehyde based dimethylol dihydroxyethyleneurea, diethylene glycol based resin or glyoxal based resin free from formaldehyde.
8. The method as claimed in claim 6 wherein the pH of the composition is adjusted using acetic acid.