1. Waterproof performance test standards</p
Textile waterproof performance testing is also called water resistance testing, which is mainly divided into water penetration resistance (hydrostatic pressure) testing, surface water repellency (spray) testing and rain testing. The commonly used testing methods at home and abroad are shown in Table 1 below: </ p
Table 1 Main testing standards at home and abroad</p
</p
The national standards in the above table and the technical methods of the Japanese JIS method system are basically equivalent to ISO. The main difference between the AATCC method and ISO is that AATCC’s hydrostatic pressure test only requires at least 3 samples, while The rating of the spray test uses a scoring system and can be rated at an intermediate level; while the rain test uses a different rain meter and only measures the quality changes of the absorbent paper �</p
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2. Waterproof performance test method</p
2.1 Hydrostatic pressure (ISO 811-1981)</p
2.1.1 Application scope and principle</p
Hydrostatic pressure testing is suitable for measuring the pressure when water penetrates tight fabrics (such as canvas, oilcloth, tent cloth, rainproof clothing cloth, etc.). Theoretically, the hydrostatic pressure (P) of textiles can be obtained using the following formula:</p
</p
In the formula: </p
γL——surface energy of water;</p
θ——Contact angle between the inner wall of the micropore and water;</p
r——Micropore radius;</p
g ——重力加速度。
由公式可见，当90°<θ<180°时，θ越大，织物表面能越低，微孔的半径(r)越小，静水压(P)越高。而静水压的检测结果在样品和试验液体一定的条件下，与水温、测试面积和水压上升速率有关。试验结果表明，织物的静水压性能中大约有52%是由织物表面孔径决定的，有44%是由织物表面能决定的，有4%是由其他因素决定的。故防水级别要求高的织物在织物的表面必须有微小而均匀的孔和非常低的表面能。
2.1.2 Test instruments</p
耐静水压测试仪，如图1。
</p
Figure 1 Hydrostatic pressure resistance tester</p
2.1.3 Test procedures and results</p
Take 5 representative samples from different parts of the fabric. Under normal circumstances, the water pressure rise rate is 0.59kPa/min, and the water temperature is 20°C. After conditioning the sample under standard atmospheric conditions according to regulations, the fabric test surface is in contact with water. , apply increasing water pressure to the sample, and continuously observe the phenomenon of water seepage. Record the hydrostatic pressure value at the third point of water seepage on the fabric, and repeat the test to take the average value. �检测结果的计量单位用kPa和Pa表示� �结果越大，表明抗静水压性能越好� �</p
2.2 Spray test (ISO 4920-1981)</p
2.2.1 Application scope and principle</p
喷淋检测适用于测定各种已经或未经拒水整理织物表面抗湿的能力。该性能表示液体在纺织品表面的润湿情况，与检测液体和纺织品表面的表面能和固液接触角θ有关。根据Young方程式：
</p
In the formula: </p
θ——Contact angle at the solid-liquid-gas three-phase boundary;</p
γsv——surface energy of solid and gas interface;</p
γsl——surface energy of solid-liquid interface;</p
γlv——液体与气体界面的表面能。
由公式可见，γsv一定时，γlv越小，θ越小，液体越容易润湿固体。
因而在试样、液体种类和温度一定的条件下，喷淋检测的试验结果与检测液体流速、样品在仪器上如何摆放等有关。
2.2.2 Test instruments</p
喷淋式拒水性能测试仪，如图2。
</p
Figure 2 Spray water repellent performance tester</p
2.2.3 Test steps and results</p
在织物有不同部位至少取3块具有代表性的试样� �一般情况下，水温为20℃，按规定在标准大气条件下调湿试样后，织物试验面与水接触接受喷淋，试样经向与水流方向平行� Pour 250ml of water into the funnel quickly and evenly. As soon as the water stops pouring, quickly make the holder and the fabric test surface face down and almost level. Tap it twice gently. Evaluate the observed sample according to the standard text description or picture. The level of wetting degree is from level 5 to level 1, with level 5 being good and level 1 being poor. Intermediate levels are not rated. The rating is carried out by at least 2 inspectors with experience in spray rating. �重复测试获得3个试验数据，报告每个测试样品的试验结果� �</p
2.3. Rain test (ISO 9685-1991)</p
2.3.1 Application scope and principle</p
The rain test is suitable for determining the waterproof performance of fabrics subjected to showers during exercise, including surface wetting and the ability of textiles to absorb moisture. Based on the principle of water repellency, there is also the principle of textile wetting. Young-Laplace’s can be used Equation explanation:</p
</p
In the formula: </p
γ——Surface tension of the test liquid;</p
r——radius of test hole;</p
θ——润湿液体对孔壁的接触角。
由上式可见，纺织品润湿吸水的检测结果在样品与试验液体一定的条件下，与水温、测试面积和水压有关。
2.3.2 Test instruments</p
�� Bondis door rain resistance tester, as shown in Figure 3.
</p
Figure 3 Bondis door rain resistance tester</p
2.3.3 Test steps and results</p
在织物上至少取4块代表性试样，按规定在标准大气下调湿样品。试验或校验前，先校正流量 ，移上挡雨板，称量调湿后试样的质量(m1)。试样的测试面平整无张力地放于样杯上，用夹样环夹住，拉开挡雨板，使试样受淋10min。用参比样照目测评定试样的拒水性(类似喷淋检测的评级)，试样离心脱水15s，立即称出其质量(m2)。计算吸水率(W)，以质量百分比表示，公式如下：
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3. Performance evaluation</p
目前，国际上纺织品的防水检测方法中均没有对防水性能评价的规定，相关检测机构对纺织品防水性能的评价往往是用户根据纺织品的种类和用途来确定检测要求。纺织品的用途和档次不同导致了防水性能有较大差异，评价要求也不同。由于纺织品的防水与透湿性能往往是一对矛盾的共同体，防水性能好的产品的透湿性能相对较差。目前，防水和透湿性能都好的产品往往是高档的产品，所以也极大限制了防水纺织品的使用范围。
国际上著名的防水纺织品品牌，如：“Teflon”“Scotchgard”“Gore-Tex”等品牌检测认证程序，往往是根据服用纺织品、家居纺织品或产业用纺织品等不同用途来确定产品的具体性能指标要求� �美国军用标准中防水纺织产品的耐水压低要求为13.68kPa，日本自卫队雨衣的耐水压在13.73kPa以下� �我国公共安全行业标准GA 10-1991规定，防护服抗渗水内层耐静水压不得小于3.92kPa� �而ASTM D3781要求：织物拒水性水洗前应达到4级以上，一次水洗后仍能达到3级以上;淋雨检测的要求往往是吸水质量大为1g� �GB 12799要求纺织品水洗前拒水性达到5级，水洗30次仍至少为≥1级�
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