received by the International Bureau on 29 March 2019 (29.03.2019)

1 . The invention is related to a fire retardant fiber (1 ) comprising polyacrylonitrile (PAN) (2), polyvinylchloride (PVC)(3) and a solvent (5) characterized by comprising a nano sized additive (4) and surfactant (6) in order to reduce the surface tension different between polyacrylonitrile (PAN) (2) and polyvinylchloride (PVC)(3).

2. The fiber (1 ) according to Claim 1 characterized in that it comprises 50% to 95% polyacrylonitrile (PAN) (2).

3. The fiber (1 ) according to Claim 1 characterized in that it comprises 5% to 50% polyvinylchloride (PVC) (3).

4. The fiber (1 ) according to Claim 1 characterized in that it comprises 1 % to 10% nano-sized additive (4).

5. The fiber (1 ) according to Claim 1 or Claim 4 characterized in that said nano- sized additive (4), is an inorganic material such as antimony trioxide, zinc borate, aluminum hydroxide, aluminum trioxide, magnesium hydroxide, magnesium trioxide and the like, having particle (grain) size between 5 to 750 nanometers.

6. The fiber (1 ) according to Claim 1 characterized in that it comprises 0.1 % to 2% surfactant (6).

7. The fiber (1 ) according to Claim 1 or Claim 6 characterized in that it comprises surfactant (6) such as DBS, LAS and the like.

8. A method of producing fire retardant fiber (1 ) characterized in that it comprises the following process steps;

• Adding the solvent (5) into tank 1 (7) (101 ),

• Adding polyacrylonitrile (PAN) (2) into tank 1 (7) and mixing (102) thereof,

15 Adding surfactant - nano-sized additive (12) into tank 1 (7) and dissolving (103) thereof,

Passing the polyacrylonitrile (PAN) (2) and surfactant - nano-sized additive (12) through the heat exchanger between 50-120°C for complete dissolving (104) thereof,

Adding the solvent (5) into tank 2 (8) (105),

Adding polyvinylchloride (PVC) (3) into tank 2 (8) and mixing (106),

Passing the polyvinylchloride (PVC) (3) through the heat exchanger between

50-120°C for complete dissolving (107) In tank 2 (8),

Mixing the mixtures prepared in tank 1 (7) and tank 2 (8) by the help of the static mixer (10) or dynamic mixer (1 1 ) (108),

Obtaining the fiber (1 ) by wet spinning method from final mixture (109).

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