**The Role of Nonwoven Fabric Air Permeability in the Textile Industry**

Nonwoven fabric, named for being made without traditional weaving or knitting, is a new generation of environmentally friendly material. It offers advantages such as breathability, flexibility, non-toxicity, odorlessness, and low cost, leading to its widespread application across many fields including agricultural films, shoemaking, leather processing, mattresses, chemicals, automotive, and construction. In the healthcare industry, it is used to produce surgical gowns, protective clothing, adhesive plasters, sterilization packaging, masks, and sanitary napkins. Among its various properties, good air permeability is a key reason for its extensive use. Taking medical products as an example: if the nonwoven fabric has poor air permeability, adhesive plasters made from it can cause skin allergies because they hinder normal skin respiration. Poorly breathable medical tapes like bandages can promote microbial growth near wounds, leading to infection. If protective clothing lacks adequate breathability, it significantly compromises wearing comfort. Similar to medical products, poor air permeability in other nonwoven applications can also create significant disadvantages. Therefore, strengthening the testing of nonwoven fabric air permeability is a crucial measure to ensure that products made from it meet usage requirements.

**Test Basis**

The air permeability (or air flow resistance) involved in this test characterizes the ability of air to pass through a specimen. The test procedure can be based on the method standard **GB/T 5453-1997 "Textiles – Determination of permeability of fabrics to air"**. This standard is applicable to various textile fabrics, including industrial fabrics, nonwovens, and other permeable textile products.

**Test Principle**

There are two main methods for testing air permeability: measuring flow rate under constant pressure difference and measuring pressure difference under constant flow rate. The constant pressure difference method maintains a constant pressure differential across the specimen. The air permeability is calculated by measuring the volume of air flowing through a given area of the specimen within a specified time. The constant flow rate method maintains a constant flow of air passing vertically through the specimen. The air permeability is determined by measuring the pressure differential across the specimen under these conditions. The tests described herein use the constant pressure difference method.

**Instrument Parameters**

1. Pressure difference measurement range: 0 – 1 KPa; air flow measurement range: 0 – 1800 L/h.

2. Allows users to freely choose between constant pressure difference and constant flow rate measurement modes to meet different testing needs.

3. High-precision electronic air flow and pressure sensors ensure accurate test data.

4. The system is controlled by a microprocessor with an LCD display, featuring a menu-driven interface and a PVC control panel for convenient test operation and data review.

**Scope of Application**

1. Suitable for air permeability testing of textile materials such as fabrics and nonwovens.

2. Suitable for testing air permeability and airflow resistance of automotive interior materials such as polyurethane, PVC, leather, textiles, and nonwovens.

3. Suitable for testing air permeability of porous polymeric elastic materials like foam.

4. Suitable for testing air permeability of leather materials.

5. Can also be extended to test air permeability of paper materials such as tissue paper and toilet rolls.

6. Complies with multiple national and international standards, including GB/T 5453, ISO 9237, ISO 4638, ISO 5636, GB/T 10655, GB/T 4689.22, GB/T 13764, ASTM D737, TAPPI T460, JIS P8117, etc.

**Test Procedure**

1. Randomly cut 10 test specimens with a diameter of 50 mm (specimen diameter can be selected based on specific conditions) from the surface of the medical nonwoven fabric sample.

2. Clamp one specimen in the air permeability tester, ensuring it is flat without deformation and that the seal around the specimen is tight.

3. Set the pressure difference across the specimen according to the fabric's expected permeability or relevant standards. For this test, a pressure difference of 100 Pa was set. Adjust the pressure control valve to achieve the desired pressure difference. When the set value is reached, the test stops. The instrument automatically displays the air flow rate passing through the specimen.

4. Repeat the clamping and pressure adjustment steps until all 10 specimens have been tested.

**Test Results**

The average air permeability of the medical nonwoven fabric samples tested was **16.13 L/h** (the average result from the 10 specimens). The test result is influenced by both the diameter of the cut specimens and the set pressure difference. Therefore, to compare the air permeability of different nonwoven samples, the specimen diameter and the pressure difference across them must be kept consistent.

Air permeability is one of the excellent properties of nonwoven materials and is a critical factor affecting the safety, hygiene, comfort, and overall performance of nonwoven products. This article demonstrates testing the air permeability of medical nonwoven fabric using an air permeability tester. The test process is simple, the instrument is easy to operate, and the results are reproducible, accurate, and precise, effectively reflecting the true air permeability of the tested samples.

无纺布透气性能在纺织行业中的作用

无纺布因不经纺织成布而得名，是新一代环保材料，具有透气、柔韧、无毒无味、价格便宜等优点，在很多领域得到应用，如农用薄膜、制鞋、制革、床垫、化工、汽车、建材等。另外在医疗卫生行业可用于生产手术衣、防护服、膏药贴、消毒包装、口罩、卫生巾等产品。在无纺布的众多应用中，良好的透气性能是其得到广泛应用的重要原因之一，以医疗行业的相关产品为例，若无纺布的透气性较差，由其制成的膏药贴则因无法满足皮肤的正常呼吸而导致使用者出现过敏症状，创可贴等医用胶带的透气性差则会引起伤口附近的微生物繁殖而导致伤口感染。防护服的透气性较差则会大大影响其穿着的舒适性，与医疗产品相似，其他无纺布产品的透气性差同样会给其使用带来诸多不利。因此，加强对无纺布透气性能的检测是保证其生产的相关产品满足使用要求的重要举措之一。

　　检测依据：

　　试验中涉及的透气性能(透气度)是表征空气透过样品的能力，测试过程可依据方法标准GB/T 5453-1997《纺织品 织物透气性的测定》，该标准适用于多种纺织织物，包括产业用织物、非织造布和其他可透气的纺织制品。

　　试验原理：

　　透气度的测试方法主要包括两种，分别为恒定压差测流量与恒定流量测压差。其中恒定压差测流量法是指在试样的两侧保持恒定的压差，通过测试在一定时间内透过试样给定面积的空气流量，计算试样的透气度；恒定流量测压差法则是指使垂直通过试样的空气流量保持恒定，通过测试在该条件下试样两侧的压差，得到试样的透气度。本文的检测过程采用恒定压差测流量法。

　　设备参数：

　　1.压差测量范围为0 ~ 1 KPa，流量的测量范围为0 ~ 1800 L/h。

　　2.定压差、定流量两种测量方式供用户自由选择，满足不同的测试需求。

　　3.高精度电子气流、气压传感器确保测试数据的准确性。

　　3.系统采用微电脑控制、液晶显示，搭配菜单式界面和PVC控制面板，方便用户快速地进行试验操作及数据查看。

　　适用范围：

　　(1)适用于纺织品材料的透气性测试，如布料、无纺布等。

　　(2)适用于汽车内饰件材料空气透过率与空气阻力的测试，如聚氨酯、PVC、皮革、纺织品、非织造布等。

　　(3)适用于高聚物多孔弹性材料的空气透过率测试，如海绵等。

　　(4)适用于皮革材料的透气度测试。

　　(5)还可扩展应用于纸张材料的空气透过率测试，如日用抽纸、卷纸等。

　　(6)可满足多项国家和国际标准,如GB/T 5453、ISO 9237、ISO 4638、ISO 5636、GB/T 10655、GB/T 4689.22、GB/T 13764、ASTM D737、TAPPI T460、JIS P8117等。

　　试验过程：

　　(1)从医用无纺布样品表面随机裁取直径为50mm(试样直径可根据具体情况选择)的试样10片。

　　(2)取其中一片试样装夹在透气度测试仪中，使试样平整，不发生变形，且试样两侧密封性良好。

　　(3)根据试样的透气度或相关标准要求设置试样两侧的压差值，本次试验设置的压差值为100Pa。调节压力控制阀，调整试样两侧的压差,当压差值达到设定值时，试验停止。设备自动显示此时透过试样的气体流量。

　　(4)重复装样、调节压力控制阀操作，直至10片试样测试完成。

　　试验结果：

　　本次检测的医用无纺布样品的透气度测试结果为16.13 L/h(该结果为10片试样试验结果的平均值)。裁取的试样直径及设置的压差值不同均对试验结果有影响，故若要对比不同无纺布样品的透气性能，应使试样直径及其两侧压差值保持一致。

　　透气性能是无纺布材料具有的优异性能之一，是影响无纺布制品安全卫生性、舒适性等使用性能的重要因素。本文中利用透气性检测仪对医用无纺布透气性能进行了检测，试验的过程简单，设备易于操作，试验结果的重复性及准确性好，测试精度较高，可真实的反映所测试样品的透气性能。