DESC:FIELD
The present disclosure relates to polyolefinic compositions having insect repelling properties.
BACKGROUND
Incidences of diseases caused by Arthropods are on the rise, some of the Arthropod-borne diseases can be prevented by vaccination or preventive use of specific medications. However, for many of the arthropod-borne diseases, the only preventive measure available is avoiding arthropod bites. Mosquitoes are small, midge-like flies, belonging to the Phylum, Arthropoda. Mosquitoes are one of the most significant vectors, capable of transmitting a number of parasites and pathogens. Mosquitoes are responsible for spreading diseases such as dengue, malaria, filariasis and chikungunya.
Smoking coils, lotions, liquidators and anti-insect sprays are known to be effective in avoiding insect bites. However, these contain chemicals like N, N-Diethyl-3-methylbenzamide (DEET), which is harmful, especially for children.
An alternative solution for avoiding insect bites is, using insect repellent fabrics comprising insect repellents (insecticides). The insect repellent fabrics are extremely useful, as a protection method from insect bites. Insecticides can be integrated into the polymer material, which prevents the insects from working their way inside the fabrics. The type of material used for the insect repellent fabric and the release rate of the insecticides in the polymer matrix, are important parameters responsible for the efficiency of the insect repellent fabrics. A very fast release of the insecticides will exhaust the desired effect rapidly; whereas a slow release will affect the controlling/killing performance of the insect repellent fabric.
The insecticidal dose on the surface of the insect repellent fabrics needs to be sufficiently high for the killing of the insects. The insecticide release should also last for a comparatively longer time and the fabric should not lose its activity even after repeated washing. Also, the overall content of the insecticide in the polymer matrix needs to be controlled to prevent overexposure to a user and therefore, cause harm to a user using the fabric. Finally, the insect repellent fabric needs to be affordably priced.
Conventionally, the insect repellent fabrics use acrylate based binder for coating. Although, acrylate based binders increase the washing fastness of the fabric containing the insect repellent, the use of such binders cause discoloration of the fabric, because of oxidation, when exposed to air. Moreover, these binders are toxic. Usually, the fabrics are soaked in an insecticide solution, which makes the fabric uncomfortable for a user. Additionally, such a fabric emits an unpleasant odor.
There is therefore felt a need for insect repellent fibers that mitigate the drawbacks mentioned hereinabove.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Another object of the present disclosure is to provide an insect repellent hydrophilic polyolefin fiber.
Still another object of the present disclosure is to provide an insect repellent polyolefin fiber, having an improved insecticidal activity and an improved retention of the insecticide after repeated washing.
Yet another object of the present disclosure is to provide a process for preparing insect repellent hydrophilic polyolefin fibers.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
In accordance with one aspect of the present disclosure, there is provided insect repellent hydrophilic polyolefin fibers. Each of the insect repellent hydrophilic polyolefin fiber comprises a core region and a clad region which surrounds and is direct contact with the core region. The core region is made of a modifier composition comprising a polyolefin in an amount in the range of 98.0 wt% to 99.3 wt% of the fiber, at least one hydrophilic additive in an amount in the range of 0.5 wt% to 1.0 wt% of the fiber and at least one first insecticide in an amount in the range of 0.2 wt% to 1.0 wt% of the fiber. The polyolefin can be selected from the group consisting of polypropylene homopolymer, copolymers of polypropylene, and blends thereof. The clad region is made of a cladding composition comprising at least one hydrophilic binder in an amount in the range of 0.5 wt% to 5.0 wt% of the fiber and at least one second insecticide in an amount in the range of 0.2 wt% to 1.0 wt% of the fiber.
The insect repellent hydrophilic polyolefin fibers can be used for the preparation of insect repellent fabrics such as Long Lasting Insecticidal Nets (LLINs).
In accordance with another aspect of the present disclosure, there is provided a process for preparing the insect repellent hydrophilic polyolefin fibers. The process includes mixing at least one hydrophilic additive, at least one first insecticide and at least one polyolefin to obtain a mixture. The mixture is melt blended to obtain a melt blend, followed by spinning the melt blend to obtain extruded elongated core region elements, which are then cladded with a cladding composition in a fluid medium, comprising at least one hydrophilic binder and at least one second insecticide, to obtain cladded fibers. The cladded fibers are then dried to obtain the insect repellent hydrophilic polyolefin fibers envisaged in accordance with the present disclosure.
DETAILED DESCRIPTION
Insect-borne diseases afflict millions of people every year, resulting in a high number of deaths. Vaccines and therapeutic drugs are not available to treat a large number of the insect-borne diseases. Insect repellent fabrics are considered to be an important tool to reduce the incidence of insect-borne diseases, such as malaria, dengue, encephalitis, chikungunya and the like.
Accordingly, the present disclosure envisages an insect repellent fabric that is effective against a large number of insects and at the same time is economical and easily available.
In accordance with one aspect of the present disclosure, there are provided insect repellent hydrophilic polyolefin fibers. The insect repellent hydrophilic fibers of the present disclosure comprise a core region and a clad region. The clad region surrounds and is in direct contact with the core region.
The core region is made of a modifier composition comprising a polyolefin, at least one hydrophilic additive and at least one first insecticide.
The polyolefin can be selected from the group consisting of polypropylene homopolymer, copolymers of polypropylene, and blends thereof. Typically, the amount of polypropylene can be in the range of 98.0 wt% to 99.3 wt% of the fiber.
The hydrophilic additives can be selected from the group consisting of phenol ethoxylate, alcohol based long chain phosphate esters, metal alkoxide such as alkoxy silanes, titanium alkoxide and boron alkoxide, and combinations thereof. Typically, the amount of the hydrophilic additives can be in the range of 0.5 wt% to 1.0 wt% of the fiber.
In an embodiment of the present disclosure, the first insecticide is a pyrethroid group insecticide. The pyrethroid group insecticide can be selected from the group consisting of deltamethrin, transfluthrin, lambda-cyhalothrin, beta-cyfluthrin and combinations thereof. Typically, the amount of the first insecticide can be in the range of 0.2 wt% to 1.0 wt% of the fiber.
The clad region is made of a cladding composition. The cladding composition comprises at least one hydrophilic binder and at least one second insecticide. Typically, the clad region surrounds and is in direct contact with the core region.
The hydrophilic binder can be selected from the group consisting of polyvinyl alcohol (PVA), poly ethylene glycol (PEG) and combinations thereof. The amount of the hydrophilic binder can be in the range of 0.5 wt % to 5.0 wt % of the fiber.
In an embodiment of the present disclosure, the second insecticide is a pyrethroid group insecticide. The pyrethroid insecticide can be selected from the group consisting of deltamethrin, transfluthrin, lambda-cyhalothrin, beta-cyfluthrin and combinations thereof. The amount of the second insecticide can be in the range of 0.2 wt% to 1.0 wt% of the fiber.
In another aspect of the present disclosure, there is provided a process for preparing the insect repellent hydrophilic polyolefin fibers. The process comprises mixing at least one hydrophilic additive, at least one first insecticide and at least one polyolefin to obtain a mixture, which is melt blended and spun to obtain extruded elongated core region elements. The core region elements are cladded with a cladding composition in a fluid medium, followed by drying to obtain the insect repellent hydrophilic polyolefin fibers of the present disclosure. The process is hereinafter described in detail.
Initially, at least one at least one hydrophilic additive, at least one first insecticide and the polyolefin are mixed together to obtain a mixture.
The polyolefin can be selected from the group consisting of polypropylene homopolymer, copolymers of polypropylene, and blends thereof. Typically, the amount of polypropylene can be in the range of 98.0 wt% to 99.3 wt% of the fiber.
The hydrophilic additive can be selected from the group consisting of phenol ethoxylate, alcohol based long chain phosphate esters, metal alkoxide such as alkoxy silanes, titanium alkoxide and boron alkoxide, and combinations thereof. Typically, the amount of the hydrophilic additive in the insect repellent hydrophilic polyolefin fibers can be in the range of 0.5 wt % to 1.0 wt % of the fiber.
In one embodiment of the present disclosure, the at least one first insecticide is a pyrethroid group insecticide. The pyrethroid insecticide can be selected from the group consisting of deltamethrin, transfluthrin, lambda-cyhalothrin, beta-cyfluthrin and combinations thereof. Typically, the amount of the first insecticide in accordance with the present disclosure can be in the range of 0.2 wt% to 1.0 wt% of the fiber.
The mixture so obtained is melt blended in an extruder, to obtain the extruded elongated core region elements. Typically, the diameter of the extruded elongated core region elements can be in the range of 120 µm to 140 µm. Typically, the extrusion can be carried out at a temperature in the range of 200° C to 250 °C.
The extruded elongated core region elements, so obtained are then cladded with a cladding composition. The cladding composition comprises at least one hydrophilic binder and at least one second insecticide, prepared in a fluid medium. In one embodiment, the fluid medium is water. Though the extruded elongated core regions are passed through the cladding composition comprising 5 wt% hydrophilic binder and 0.7 wt% second insecticide, it is observed that only a small amount of the second insecticide in the range of 0.02 wt% to 0.07 wt% is coated on the cladded fibers.
The hydrophilic binder can be selected from the group consisting of polyvinyl alcohol, poly ethylene glycol and combinations thereof. The amount of the hydrophilic binder can be in the range of 0.5 wt% to 5.0 wt% of the fiber.
In an embodiment of the present disclosure, the second insecticide is a pyrethroid group insecticide. The pyrethroid insecticide can be selected from the group consisting of deltamethrin, transfluthrin, lambda-cyhalothrin, beta-cyfluthrin and combinations thereof. The amount of the second insecticide can be in the range of 0.2 wt% to 1.0 wt% of the fiber.
The cladding of the extruded elongated core region elements can be carried out using a known method, such as, dip coating and spray coating.
The extruded elongated core region elements cladded with the cladding composition are then dried at a temperature in the range of 120° C to 150° C to obtain the insect repellent hydrophilic polyolefin fibers of the present disclosure.
The insect repellent hydrophilic polyolefin fibers of the present disclosure can be used for making textiles/fabrics, such as Long Lasting Insecticidal Nets (LLINs), which protect the user from insects.
The insect repellent hydrophilic polyolefin fibers of the present disclosure contain the first insecticide in the core region and the second insecticide on the clad region of the insect repellent hydrophilic polyolefin fiber. This results in an enhanced insecticidal activity and an improved retention of the insecticide, even after repeated washing of the insect repellent hydrophilic polyolefin fibers. Typically, the insect repelling capacity if the fabric made from the fibers of the present disclosure lasts up to 25 washings.
Use of the hydrophilic binder imparts a better feel to the insect repellent hydrophilic polyolefin fibers and also makes them less toxic.
The present disclosure is further described in light of the following laboratory scale experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. These laboratory scale experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial/commercial scale.
Experimental details
Experiment 1: Preparation of the insect repellent hydrophilic polyolefin fibers in accordance with the present disclosure
491.5 g of polypropylene granules were mixed with 5 g of hydrophilic additives (P 710 + alkoxy silane) and 3.5 g of first insecticide (beta Cyfluthrin) gently to obtain a mixture and the mixture was fed into a single-screw extruder and melted at 230 °C. The so obtained melt blend mixture was passed through a spinneret to obtain extruded elongated core region. The extruded elongated core region obtained was further passed through a cladding composition at room temperature to obtain cladded fibers. The diameter of the extruded elongated core region was found to be 125 µm. The cladding solution was prepared by mixing 50 g of polyvinyl acetate as a hydrophilic binder and 7 g of second insecticide in 1000 ml of water. Though the extruded elongated core region was passed through the cladding composition comprising 5 wt% hydrophilic binder and 0.7 wt% second insecticide, it was found that only 0.05 wt% of the second insecticide was coated on the cladded fibers. The cladded fibers were dried at a temperature of 135 ° C to obtain the insect repellent hydrophilic polyolefin fibers.
Experiment 2: Characterization of the insect repellent hydrophilic polyolefin fibers prepared in accordance with the present disclosure
The hydrophilicity of the insect repellent hydrophilic polyolefin fibers obtained by the process of the present disclosure was examined by measuring the contact angle, deflection of the fibers and the diameter of water droplet using a microscope. The deflection studies were carried out by dipping the insect repellent hydrophilic polyolefin fibers in a mixture of organic fluid medium and polar fluid medium. The organic fluid medium used was n-decane and the polar fluid medium used was water. The deflection values obtained for the insect repellent hydrophilic polyolefin fibers prepared by the process of the present disclosure are summarized in Table-1. Polypropylene was used as the polyolefin for all the studies.

Table-1
S. No. Polypropylene
(wt%) Additives in core region Additives in clad region Deflection of fiber
(mm) Diameter of water droplet using microscope
(pxi)
1 100 No additives No additives 0 329
2 98.3 1 wt % P 710 + alkoxy silane + 0.7 wt% (7 g per kg) Deltamethrin 5 wt % PEG + 0.7 wt% (7 g per kg) beta Cyfluthrin 11 521
3 98.7 1 wt% P 710 + alkoxy silane + 0.3 wt% (3 g per kg) Transfluthrin 5 wt% PEG + 0.7 wt% (7 g per kg) beta Cyfluthrin 9 490
4 98.3 1 wt% P 710 + alkoxy silane + 0.7 wt% (7 g per kg beta) Cyfluthrin 5 wt% PVA + 0.7 wt% (7 g per kg) Deltamethrin 12 543
5 98.7 1 wt% P 710 + alkoxy silane + 0.3 wt% (3 g per kg) Transfluthrin 5 wt% PVA + 0.7 wt% (7 g per kg)Deltamethrin 10 456
P-710= tridecyl alcohol ethoxylate phosphate ester, Alkoxy silane= Tetra Ethoxy silane

It is known that the water droplet becomes wider on a hydrophilic surface as compared to a hydrophobic surface, which can be determined by measuring the diameter of the water droplets formed on the respective surfaces. It is clearly seen from Table-1, that wider water droplets were obtained from the insect repellent polyolefin fibers (Serial No. 2 to 5) of the present disclosure as compared to the conventional fibers (Serial No. 1) without the hydrophilic additive and the hydrophilic binder. From Table-1 it is evident that the fiber with Serial No. 1 shows no deflection, whereas the fibers of Serial No. 2 to 5 show defection. The deflection of the polyolefin fibers of the present disclosure towards the polar fluid medium, also indicate the hydrophilic nature of the insect repellent hydrophilic polyolefin fibers.
Experiment 3: Assessing the efficacy of LLINs prepared from the insect repellent hydrophilic polyolefin fibers of the present disclosure
The WHO cone bioassay method was used for assessing the efficacy of Long Lasting Insecticidal Nets (LLINs) that were prepared using the insect repellent hydrophilic polyolefin fibers of the present disclosure and conventional nets without the insecticides. In the WHO cone bioassay method, a plastic cone was used and fabric (test sample having insecticide and conventional samples without the insecticides) was fixed on the rim of the inverted cone to obtain a covered cone. Ten mosquitoes were introduced into the covered plastic cone through orifices and then the orifices were plugged with cotton wool. The number of mosquitoes knocked down at the end of 3 minutes, 1 hour and 24 hours were recorded. The knocked down mosquitoes were retrieved and kept in another chamber using reviving sugar in cotton wool, at 27° C and 70 % relative humidity for 24 hours. The mortality (%) was calculated by determining the number of mosquitoes that did not revive after 24 hours. The mortality (%) of the test sample (with insecticide) and the conventional sample (without insecticide) were determined after 24 hours of holding the knocked down mosquitoes and the results obtained are summarized in Table-2 (the samples were assessed as is; without washing) and Table-3 (the samples were assessed after 20 washing).

Table-2

S. No. Additives in core region Additives in clad region No. of mosquitoes knocked down after 3 minutes No. of mosquitoes knocked down after 1 hour No. of mosquitoes knocked down after 24 hours Mortality (%)
1 1 wt% P 710 + alkoxy silane + 0.7 wt% (7 g per kg) Deltamethrin 5 wt% PEG + 0.7 wt% (7 g per kg) beta Cyfluthrin 10 0 0 100
2 1 wt% P 710 + alkoxy silane + 0.3 wt% (3 g per kg)Transfluthrin 5 wt% PEG + 0.7 wt% (7 g per kg) beta Cyfluthrin 10 0 0 100
3 1 wt% P 710 + alkoxy silane + 7 g per kg Cyfluthrin 5 wt% PVA + 7 g per kg Deltamethrin 10 0 0 100
4 1 wt% P 710 + alkoxy silane + 0.3 wt% (3 g per kg) Transfluthrin 5 wt% PVA + 0.7 wt% (7 g per kg)Deltamethrin 10 0 0 100
5 No additive No additive 0 0 0 0

It is clearly seen from Table-2 that the Insecticidal Nets prepared using the insect repellent hydrophilic polyolefin fibers of the present disclosure (Serial No. 1 to 4) are highly efficient and are capable of knocking down the mosquitoes as compared to the Insecticidal Nets prepared using conventional fibers (Serial No. 5), without the insecticides. None of the mosquitoes that were knocked down survived after 24 hours for the test samples, indicating significant insect repelling capacity. However, all the mosquitoes survived when the conventional fibers for the net were used.

Table-3
S. No. Additives in core region Additives in clad region No. of mosquitoes knocked down after 3 minutes No. of mosquitoes knocked down after 1 hour No. of mosquitoes knocked down after 24 hours Mortality (%)
1 1 wt% P 710 + alkoxy silane + 0.7 wt% (7 g per kg)Deltamethrin 5 wt% PEG + 0.7 wt% (7 g per kg) beta Cyfluthrin 0 0 10 100
2 1 wt% P 710 + alkoxy silane + 0.3 wt% (3 g per kg) Transfluthrin 5 wt% PEG + 0.7 wt% (7 g per kg) beta Cyfluthrin 0 0 10 100
3 1 wt% P 710 + alkoxy silane + 0.7 wt% (7 g per kg) Cyfluthrin 5 wt% PVA + 0.7 wt% (7 g per kg)Deltamethrin 0 0 10 100
4 1 wt% P 710 + alkoxy silane + 0.3 wt% (3 g per kg) Transfluthrin 5 wt% PVA + 0.7 wt% (7 g per kg) Deltamethrin 0 0 10 100
5 No additive No additive 0 0 0 0

It is clearly seen from Table-3 that the test samples prepared using the insect repellent hydrophilic polyolefin fibers of the present disclosure (Serial No. 1 to 4), retained the insect repelling capacity even after being subjected to repeated washing, whereas the conventional sample (Serial No. 5) did not have the insect repelling capacity.
From the results obtained in Table-2 and Table-3 it can be summarized that the insect repellent hydrophilic polyolefin fibers of the present disclosure can be used for preparing Long Lasting Insecticidal Nets (LLINs) as the insecticides repel the mosquitoes and prevent the user from being bitten by the mosquitoes.
The insect repellent hydrophilic polyolefin fibers of the present disclosure contain a first insecticide in the core region and a second insecticide in the clad region, leading to enhanced insecticidal activity and in an improved retention of the insecticide even after repeated washing of the insect repellent hydrophilic polyolefin fiber. Further, the use of the hydrophilic binder imparts a better feel to the insect repellent hydrophilic polyolefin fibers and also makes them less toxic.
The insect repellent hydrophilic polyolefin fibers of the present disclosure can be used for making textiles/fabrics, such as Long Lasting Insecticidal Nets (LLINs), which protect the user from insects.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
? a fiber having an improved insecticidal activity and an improved retention of the insecticide even after repeated washings of the insect repellent hydrophilic polyolefin fibers and the fabric made therefrom;
? an improved feel of the fabric made from the insect repellent hydrophilic polyolefin fibers;
? less toxic insect repellent fibers and fabric made therefrom, due to the use of PEG and PVA in the insect repellent fibers as compared to the conventional acrylate based additives; and
? a simple and efficient process for preparing the insect repellent hydrophilic fibers.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:1. Insect repellent hydrophilic polyolefin fibers, each comprising:
a. a core region made of a modifier composition comprising:
i. at least one polyolefin in an amount in the range of 98.0 wt% to 99.3 wt% of said fiber;
ii. a hydrophilic additive in an amount in the range of 0.5 wt% to 1.0 wt% of said fiber; and
iii. a first insecticide in an amount in the range of 0.2 wt% to 1.0 wt% of said fiber; and
b. a clad region surrounding and in direct contact with the core region, said clad region made of a cladding composition comprising:
i. a hydrophilic binder in an amount in the range of 0.5 wt% to 5.0 wt% of said fiber; and
ii. a second insecticide in an amount in the range of 0.2 wt% to 1.0 wt% of said fiber.
2. The fibers as claimed in claim 1, wherein said at least one polyolefin is selected from the group consisting of polypropylene homopolymer, copolymers of polypropylene, and blends thereof.
3. The fibers as claimed in claim 1, wherein said hydrophilic additive is at least one selected from the group consisting of phenol ethoxylate, alcohol based long chain phosphate esters, and metal alkoxides.
4. The fibers as claimed in claim 1, wherein said hydrophilic binder is at least one selected from the group consisting of polyvinyl alcohol and polyethylene glycol.
5. The fibers as claimed in claim 1, wherein said first insecticide and said second insecticide are independently selected from the group consisting of pyrethroid insecticides.
6. The fibers as claimed in claim 5, wherein said pyrethroid insecticide is selected from the group consisting of deltamethrin, transfluthrin, lambda-cyhalothrin, beta-cyfluthrin, and mixtures thereof.
7. A process for preparing insect repellent hydrophilic polyolefin fibers, said process comprising the following steps:
a. mixing a hydrophilic additive, a first insecticide, and at least one polyolefin to obtain a mixture;
b. melt blending said mixture at a temperature in the range of 200° C to 250° C to obtain a melt blend;
c. spinning said melt blend to obtain extruded elongated core region elements having diameter in the range of 120 µm to 140 µm;
d. cladding said extruded elongated core region elements with a cladding composition in a fluid medium, said cladding composition comprising a hydrophilic binder and a second insecticide, to obtain cladded fibers; and
e. drying said cladded fibers at a temperature in the range of 120° C to 150° C, to obtain said insect repellent hydrophilic polyolefin fibers.
8. The process as claimed in claim 7, wherein said polyolefin is selected from the group consisting of polypropylene and copolymers thereof.
9. The process as claimed in claim 7, wherein said fluid medium is water.
10. An insect repellent fabric prepared using said insect repellent hydrophilic polyolefin fibers as claimed in claim 1, wherein the insect repelling capacity of said insect repellent fabric lasts up to 25 washing cycles.