KR0125706B1 - Method of manufacturing aromatic polyamide spunbond nonwoven fabrics - Google Patents

Abstract

The aromatic polyamide spun-bonded nonwoven fabric with high heat-resistance above the pyrolysis temperature and high strength is produced by the following procedure: After completely dissolving aromatic polyamide (polyparaphenylene terephthalamide polymer of proper viscosity 3.0 or above) in strong sulfuric acid at 80 deg.C, desaturating under vacuum, and filtering, it is put into an emission base with a 0.04-0.12mm orifice. The material emitted from the emission base is gathered on an iron plate by spraying 10% sulfuric acid solution on the plate while moving it at right angle to the emission. The produced spun-bonded nonwoven fabric is coagulated by 4% sulfuric acid solution and neutralized by 1% sodium hydroxide solution. The final product is obtained by completely washing, winding on a roll, pressing, and drying the nonwoven fabric.

Description

Aromatic Polyamide Spunbond Nonwoven Fabric and Method for Manufacturing the Same

No drawing.

The present invention relates to an aromatic polyamide spunbond nonwoven fabric and a method for producing the same, and more particularly, to a method for producing an aromatic polyamide spunbond nonwoven fabric having a high heat resistance and high strength by a very simple process.

Spun-bonded fabric is a non-woven fabric made by spinning a chemical fiber, and is a kind of non-woven fabric made by blowing a fiber from a nozzle onto a running conveyor to form a long layer of fiber on the conveyor. However, polyester spunbond nonwoven fabrics that have been manufactured and used in the past have disadvantages of low heat resistance.

Chemical fiber non-woven fabric is prepared by polymerizing existing polymer, dissolving it in strong acid such as sulfuric acid, making it into fiber using air gap spinning through detention, cutting it to a certain length to make short fiber and needle punching these short fibers By the complicated process of obtaining a nonwoven fabric.

The present invention is to solve the problems of the prior art as described above, the present invention is to provide an aromatic polyamide spunbond nonwoven fabric having a high heat resistance and high strength of pyrolysis temperature of 450 ℃ or more by a simple process.

In order to achieve the above object, the present invention provides an optically anisotropic spinning dope by dissolving the aromatic polyamide in concentrated sulfuric acid, and extruded it onto a conveyor support which is defoamed and passed through a filter to pass through a detention. A method for producing an aromatic polyamide spunbond nonwoven fabric which consists of coagulating, neutralizing, washing with water and drying.

The present invention is described in more detail as follows.

In the present invention, the aromatic polyamide is prepared by polymerizing an aromatic diamine and an aromatic dieside chloride in an amide or urea polymerization solvent.

Usable amide or urea solvents include N-methylpyrrolidone (NMP), hexamethylphosphoramide (HMPA), N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF) , N, N, N ', N'-tetramethylurea (TMU) or mixtures thereof can be used.

One or two or more kinds of CaCl ₂ , LiCl, LiBr, AlCl ₃ , ZnCl _2, or KI may be added to the polymerization solvent to improve solubility and intrinsic viscosity of the final product.

Representative examples of the aromatic polyamide usable in the present invention are polyparaphenylene terephthalamide polymers obtained by polymerizing equimolar amounts of paraphenylene diamine and terephthaloyl chloride, preferably having an intrinsic viscosity of 3.0 or more. When the intrinsic viscosity is less than 3.5, the sulfate of the polymer does not properly exhibit anisotropy and the physical properties of the final product are lowered.

Preparation of the spinning dope sulfate is as follows. The aromatic polyamide is added to concentrated sulfuric acid at a concentration of 99.0% to 100.1%, completely dissolved at 80 ° C, degassed under vacuum, and then passed through a filter to the spinneret. In the present invention, it is preferable to use a spinneret having an orifice diameter of 0.04 mm to 0.12 mm.

Next, the fibrous material obtained by extrusion spinning through a spinneret is received by a moving conveyor. The conveyor may be moved while constantly moving in the vertical direction in which the conveyor is advanced. What can be used as a conveyor can be a glass plate, a stainless steel plate, etc., If it has corrosion resistance, it can use any material. In addition, the conveyor may be in the form of a mesh or plate. The density of the spunbonded nonwoven fabric can be adjusted according to the moving speed and spinning speed of the conveyor.

The sulfuric acid dope discharged directly above the conveyor from the spinneret is entangled with each other because it is not completely solidified. The entangled fibrous material is then coagulated by a coagulant which is water or aqueous sulfuric acid solution.

The spunbonded nonwoven fabric coagulated by coagulation liquid is acidic, so it is neutralized with basic aqueous solution and washed with excess water if necessary. In the neutralization step, an aqueous solution such as sodium hydroxide or calcium hydroxide is used as the neutralizing solution, and the neutralizing solution is sprayed onto the spunbond nonwoven fabric or the spunbond nonwoven fabric is impregnated with the neutralizing liquid.

The neutralized spunbond nonwoven fabric is dried using a Godet roller or dried by hot air drying. It can also be dried using a combination of Godet rollers and hot air. Another laboratory method may be drying by pressing heat, such as by ironing.

Hereinafter, the preferred embodiments of the present invention will be described in more detail.

Example 1

A) Preparation of Polymer

After dissolving 37 g of LiCl as an additive to 1000 ml of anhydrous dimethyl acetamide, the temperature was kept at 60 ° C, and 54.4 g of paraphenylene diamine was added thereto, followed by sufficient stirring. After the temperature was lowered to 20 ° C., 102.1 g of terephthaloyl chloride was added to carry out polymerization. The intrinsic viscosity of the polyparaphenylene terephthalamide polymer thus prepared was 5.8.

B) Preparation of Spinning Doping Sulphate

The polyparaphenylene terephthalamide prepared by the method of A) was dissolved in 99.7% sulfuric acid with a polymer solid content of 19.5% by weight to prepare a spinning sulfuric acid dope having optical anisotropy, which was degassed at a vacuum degree of 0.3 Torr for 20 minutes. It was transferred to the spinneret through and discharged through a spinneret having 100 orifices of 0.08 mm in diameter and 0.24 mm in length using a gear pump.

C) Preparation of Spunbond Nonwovens

The material discharged into the fibrous form through the spinneret was received on the iron plate while moving the stainless steel plate in the vertical direction of the fiber discharge direction and also moving from side to side. The spunbonded non-woven material obtained by entangled here was solidified with 4% sulfuric acid aqueous solution after 0.2 seconds after being received in a stainless steel sheet, neutralized by spraying with 2% aqueous sodium hydroxide solution, and then washed thoroughly by spraying excess water. . The neutralized and washed spunbonded nonwoven fabric was wound around a roll, and the spunbonded nonwoven fabric thus prepared was pressed and dried with an electric iron.

The strength of the spunbonded nonwoven fabric obtained as described above was 40 kg / 3 cm, and it was confirmed by the thermal decomposition test that pyrolysis started at 480 degreeC.

Example 2

A) Preparation of Polymer

After dissolving 27 g of CaCl ₂ and 20 g of KI as an additive in 1000 ml of anhydrous N-methylpyrrolidone, it was maintained at 60 ° C., 54.4 g of paraphenylenediamine was added thereto, and the mixture was sufficiently stirred to dissolve. After the temperature was lowered to 25 ° C., 102.1 g of terephthaloyl chloride was added to conduct polymerization. The intrinsic viscosity of the polyparaphenylene terephthalamide polymer thus prepared was 6.2.

B) Preparation of Spinning Doping Sulphate

Dissolve the polyparaphenylene terephthalamide prepared by the method of A) in sulfuric acid with a concentration of 99.4% to dissolve the polymer solids to 19.9% by weight to prepare a spinning sulfate dope for optical anisotropy, and defoaming for 20 minutes at a vacuum degree of 0.2 Torr. It was conveyed to the mold through the filter and discharged through a spinneret having 100 orifices of 0.06 mm in diameter and 0.18 mm in length using a gear pump.

C) Preparation of Spunbond Nonwovens

The material discharged in the form of fiber through the spinneret was received in the iron plate while moving the stainless steel plate in the vertical direction of the fiber discharge direction, and also moving from side to side. A 10% sulfuric acid solution was sprayed onto the iron plate moving under detention. The spunbonded nonwoven material obtained by entanglement on the iron plate was solidified with 4% sulfuric acid aqueous solution 0.1 seconds after being received in a stainless steel plate, neutralized by spraying with 1% aqueous sodium hydroxide solution, and then thoroughly washed by spraying excess water. . The neutralized and washed spunbonded nonwoven fabric was wound around a roll, and the spunbonded nonwoven fabric thus prepared was pressed and dried with an electric iron.

The strength of the spunbonded nonwoven fabric obtained as described above was 37 kg / 3 cm, and it was confirmed by the pyrolysis test that pyrolysis started at 520 ° C.

Claims (8)

Aromatic polyamides prepared by dissolving aromatic polyamides in concentrated sulfuric acid to produce optically anisotropic spinning dope, degassing them, passing them through a filter, extruded on a moving conveyor support, entangled, and then solidified, neutralized, washed, and dried. Method for producing an amide spunbond nonwoven fabric. The method of claim 1 wherein the conveyor support is a stainless steel sheet or glass sheet. 2. A method according to claim 1, wherein the direction of movement of the conveyor support is perpendicular to the direction of extrusion from the detention and also moves side to side. The method of claim 1, wherein the coagulation is carried out using water or an aqueous sulfuric acid solution as a coagulation solution. The method according to claim 1, wherein the neutralizing and washing methods are performed by impregnating the neutralizing liquid or spraying the neutralizing liquid. The method according to claim 5, wherein the neutralizing liquid is sodium hydroxide or an aqueous solution of sodium hydroxide. The method of claim 1 wherein the drying method is performed simultaneously or separately using heat and pressure. An aromatic polyamide spunbond nonwoven consisting of polyparaphenylene terephthalamide long fibers and having a pyrolysis temperature of at least 450 ° C.