In this paper investigated that filtration property of nonwoven fabric. Nonwoven, as a filtering medium were widely preferred in the technical textile sector.Nonwoven filters were designed according to their end uses. That is nonwoven fabric produced by using needle punch and thermal bonding technique.

Keywords: Needle punch, Thermal bond, Air filter, Air permeability, Porosity.

  1. Introduction

Air pollution is a major environmental health problem affecting everyone. It occurs when the environment is contaminated by a chemical, physical or biological agent that modified the natural characteristics of the atmosphere. Motor vehicles, industrial facilities and forest fires are common sources of air pollution. It is responsible for exacerbation of asthma and increase in respiratory infections especially in children. Increased morbidity and mortality, due to cardiovascular diseases including stroke, chronic respiratory diseases and cancers have also been attributed to air pollution. These facts indicate that air pollution is now the world’s largest single environmental health risk.

In this studied, polyester staple fibers used for producing a needle punch and thermal bonding fabric. The nonwoven fabric is more porous structure, fabric than woven fabric. They are widely used in filtration industry for filter application. Such as we were produce needle punch fabric fives sample and thermal bonding fabric five samples. The main object of this study we was find out the which fabric most suitable for filter application. There are both nonwoven fabric have different filtration characteristics like as air permeability, bursting strength, pore size and porosity. But in filter application the porosity of fabric is very important properties in filter cloth.

  1. Terms and Definition

Needle Punch Nonwoven fabric:

Needle punching is process of mechanically interlocking fibers webs by using barbed needle to reposition some of the fibers from a horizontal to vertical orientation. There are thousands no. of needle interlock fibers in a web. The needle punch fabric shown in fig. 1a.

Thermal Bonding Nonwoven fabric:

The thermal bonding technique is bonding a web of fiber heat with pressure and without pressure. A wide range of fibers is available for thermal bonding. It is an environmentally clean because there are no residual ingredients to be disposed. There are two methods of thermal bonding, viz. calendar bonding and through hot air bonding.The thermal bonding fabric shown in fig. 1b.

Air filter:

To improve the purity of filtered material is the main purpose of the filtration. Sometimes filtration is used to recover solid particles. Textile filter materials are generally used for dry filtration(solid gas filtration) and wet filtration(solid liquid filtration).

3.Materials and Methods

  3.1 Raw material

The required fiber was purchased from the market. The denier of fiber is 6 Den Polyester & 4Den LM. Needlepunch fabrics, composed with 6D 100 % PET fiber. And thermal bonding fabrics composed of 6D & 4D LM 100% PET fiber. Both nonwoven technique had each five sample were produced with different five GSM. Thetable no.1 shows theproperties of fibers.

Table No 1.Properties of fibre

2Staple length (mm)6040
3Strength (gpd)4.903.47

3.2 Web preparation

Nonwoven fabric samples were prepared by needle punch and thermal bonding process. The web of required for areal density was produced by carding machine and laying of web in machine and cross direction was carried outto produce the samples. The prepared web was entangled with TRUTZSCHLER needle punch machine and bonding by YAMUNA thermal bonding machine. The detail of developing 5 samples of needle punch and 5 samples of thermal bonding, prepared from raw material, are given in Table 2 & 3 respectively. The properties of developed needle punch and thermal bond nonwoven sample are tested and compared.

 3.3 Process flow of manufacturing of needle punch and thermal                 bonding nonwoven fabric

Nonwoven sample were produce with needle punch nonwoven fabric on Trutzschler nonwoven machine and thermal bonding fabric on Yamuna thermal bonding machine. In nonwoven needle punching machine produced five samples with different GSM.  And thermal bonding machine produced five samples with different GSM. In this nonwoven technique process line is same up to cross laying machine. In this manufacturing process fiber web divided after cross layer machine i.e. one side needle punch machine and another one thermal bonding fabric. The manufacturing process flows shown in fig.01.

Fig. 1: Manufacturing process flow of nonwoven fabric

3.4Fabric Testing

3.4.1 Fabric GSM

Nonwoven fabrics find out the mass per unit area (GSM) by using ASTM D6242 standards. The specimens of the size 10.2 X10.2 cm were cut randomly from different places and weighed in electronic balance with an accuracy of 0.01 g.

3.4.2 Thickness Measurement

Thickness is the distance between one surface and it’s opposite. Nonwoven fabrics are very soft and highly compressible i.e. high pressure would givean inaccurate result of thickness. As per ASTM D5729standard the thicknesses of the nonwoven fabrics were measured using digital thickness tester.

3.4.3 Air permeability

We are finding out the air permeability of nonwoven fabric as per ASTM D737-04 test method. The air permeability was tested using TEXTEST FX3300 air permeability tester. The applied pressure was selected at 125 Pa and 38 cm2area.

3.4.4 Pore size

We are finding out the pore size and their distribution as per ASTM E 1294 Test method by using capillary flow porometer (PMI). For evaluation of pore size in nonwoven fabric we are using liquid extrusion technique. In this technique, a wetting liquid Water (surface tension 72 dynes/cm2) fills the pores of the sample and pressurized gas pressure removes the liquid from the pores. There are find out differential gas pressure and flow rates through dry and wet samples were measured to calculate pore diameters.

3.4.5 Bursting Strength

The Bursting strength of the fabric was measured by using hydraulic bursting strength testeras per ASTM D 3786-13 method. The opening of the lower clamp of the instrument has diameter of 31.5 mm, 7.8 cm2.

3.4.7 Porosity

The find out the porosity as one example, the thickness of a polyester fiber web having a surface of 1m2 and a weight of 280 g/m2 was determined at a number of points and the average thickness, calculated as 2.2 mm. The volume of the fiber web is thus 0.22 cm x 10,000 cm2 = 2200 cm3 giving a density of 280/2,200 = 0.1272 g/cm3. The density of polyester fiber is 1.38 g/cm3. The relative density  of the web is thus 0.1272/1.38= 0.0921. The porosity of the web corresponds to 1- i.e. 0.9079.

.4. Result and Discussion

In this investigation, the needle punch and thermal bonding nonwoven fabric discussed on thickness, air permeability, pore size, bursting strength, orientation of fiber and porosity of different GSM fabric. Mainly the nonwoven fabric for filter application required air permeability and pore size.

4.1 Technical details of fabric:The fabric samples were prepared on Trutzschler Needle Punching machine, Yamuna thermal bonding machine and its particular are as follows:

4.2 Physical testing of fabric: These samples were tested as per standard procedure and the results are indicated in Table 2 & 3 respectively.

As shown in Table 2, these are result of needle punch fabric sample N1, N2, N3, N4 & N5 respectively. Also in Table 3, these are result of thermal bonding fabric sample T1, T2, T3, T4 & T5 respectively. The result of this sample produced by two different technique needle punch and thermal bondingwith five different GSM analyzed using Two Way Analysis of Variance.

Table No. 2 Properties of needle punch fabric










Pore Size


Bursting Strength



Table No. 3 Properties of thermal bonding fabric










Pore Size






4.2.1 Fabric thickness:

Figure 2: Thickness (mm) of nonwoven fabric

The thickness of nonwoven fabrics shown in fig.2.The statistical analysis shows that there is significant effect of needle punch and thermal bonding on fabric thickness. In both manufacturing of nonwoven fabric as GSM increases, thickness also increases. Because of keeping constant web density in carding machine and increasing the no. of layers of web in cross layers machine.

4.2.2 Air permeability:

Figure 3: Air permeability (cc/cm2/s) of nonwoven fabric

The air permeability nonwoven fabric of shown in fig.3.The statistical analysis stated that there is significant effect of needle punch and thermal bonding on fabric air permeability. In the needle punch fabric and thermal bonding fabric shows air permeability goes as per GSM increases. The each GSM of both samples thermal bonding fabrics air permeability value is more comparatively needle punched fabric. In the needle punch fabrics air permeability goes down when increasing GSM, because of areal density increase then air permeability decrease.In the case of thermal bonding fabrics results shown as same like needle punch fabric. It is affect on filter properties, the fabric density increases then resistance to air flow increases, also filter efficiency increases.

4.2.3Pore Size:

Figure 4: Pore size (micron) of nonwoven fabric

The pore size of nonwoven fabric shown in fig.4.The statistical analysis shows that there is significant effect of needle punch and thermal bonding on fabric pore size. As per results shows thermal bonding fabrics higher value than needle punch fabrics. In the needle punch fabric pore size goes down N1 to N5. Because of in case of needle punch fabric as more close structure make with higher GSM i.e. GSM increases with compactness increases. In the case of thermal bonding fabric pore size exactly opposite to needle punch fabric. In the thermal bonding fabric GSM increases air permeability increases T1 to T5, because of thermal bonding fabric fully one structure than needle punch fabric. The pore size also affect on filtration characteristic because of in air filter media particle trap when particle size is more than filter media pore size is less. In the air filtration media small particle size we can use needle punch fabric compare to thermal bonding fabric.

4.2.4 Bursting Strength:

Figure 5: Bursting Strength (Kpa) of nonwoven fabric

The bursting strength of nonwoven fabrics shown in fig.5.The statistical analysis stated that there is significant effect of needle punch and thermal bonding on fabrics bursting strength. In case of needle paunch fabric bursting strength is increases as a GSM increases sample N1 to N5. Also in case of thermal bonding fabric bursting strength is increase with GSM increases sample T1 to T5. Because of fiber entanglement and compactness is increases with increasing mass per unit area. In this testing find out the thermal bonding fabric bursting strength is less than needle punch fabric.

4.2.5 Porosity:

Figure 6: Porosity of nonwoven fabric

The porosity of nonwoven fabrics shown in fig.6.The statistical analysis shows that there is significant effect of needle punch and thermal bonding on fabric porosity. In both the fabric as GSM increases, the porosity also increases N1to N5 as well as T1 to T5. The porosity of thermal bonding fabrics is more than needle punch fabric. Because of air gaps present in thermal bonding fabric is higher than needle punch fabric. This characteristic is important for air filtration. The porosity is depends on fiber density and web areal density. In air filtration require higher porosity for to get more filtration efficiency.

.5. Conclusion:

From above results it has been concluded that nonwoven needle punch fabrics and thermal bonding fabric weight and thickness, both found inversely proportion to air permeability. Over all physical characteristics of the needle punch fabric gives the better performance for filter application than thermal bonded fabric, because of the needle punch fabric have higher bursting strength than thermal bonded fabric. Also needle punch fabrics have better air permeability, pore size and porosity.

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