【作者】 冯建永；

【导师】 张建春；

【作者基本信息】 东华大学 ， 纺织材料与纺织品设计， 2013， 博士

【摘要】 从市场调研及查阅的文献来看,目前汽车机油过滤材料的制备技术主要集中在国外,而国内所用汽车机油过滤材料主要依赖于进口。并且一些国产汽车机油过滤材料的过滤效率差、使用寿命短。为了满足国内市场对汽车机油过滤材料的使用要求,以及打破国外对机油过滤材料制备技术的垄断,有必要采用新的原料或技术,依靠自己的研发能力来制备新型国产汽车机油过滤材料及滤清器。为此,本文主要进行了以下工作。(1)通过对常用汽车机油过滤材料的结构及性能比较发现,机油过滤材料均是多孔材料,具有较好的孔隙特点,纤维呈现三维杂乱排列。要实现较好过滤效果必须具有较小的纤维直径、较小的孔径、较大的孔隙率、较小的厚度和定量、较大的透气率、较大的断裂强力及断裂伸长。通过对实际使用前后汽车机油过滤材料和空气过滤材料的结构及性能进行比较,使用后机油过滤材料及空气过滤材料的平均孔径均减小,厚度和定量均增加,透气率减小。(2)利用大麻纤维、粘胶短纤维、长绒棉纤维分别开发了大麻／棉(60/40)水刺非织造布、大麻／棉(60/40)针刺非织造布、大麻／粘胶(60/40)水刺非织造布,以及利用41.67tex的100%大麻纱线,开发了大麻平纹织物。将三种大麻非织造布及大麻机织物的孔径、过滤精度、压差进行比较,并且研究了测试面积对大麻／棉(60/40)水刺非织造布压差的影响。以开发的大麻／棉(60/40)水刺非织造布作为实验材料,研究大麻／棉水刺非织造布的过滤性能并且研究过滤过程中各个参数的变化情况。清洁油液流量和杂质颗粒质量均对压差产生影响,并且压差随着流量和杂质颗粒质量的增加而增加。通过观察杂质颗粒截留在大麻／棉水刺非织造布上的一些典型扫描电镜照片可以知道,杂质颗粒被截留在单个纤维上或被截留在两个纤维之间的孔隙。在过滤过程中,杂质颗粒的浓度是动态变化的。随着杂质颗粒粒径的增加,平均过滤比和过滤效率均增加。将开发的大麻／棉水刺非织造布和市场上过滤性能最好的5#玻璃纤维非织造布的过滤性能比较发现,开发的大麻／棉水刺非织造布的厚度、定量、孔径均较大,孔隙率比较小。将计算所得的EI、EG、ES和过滤效率的实验值E进行比较发现,EI、EG、ES和E之间有明显差异,并且EI<E<EG,ES<<E。由于乓远小于E,所以E可以忽略,可以认为在过滤过程中主要是直接拦截机理和重力沉积机理起作用。与欧三标准滤清器进行比较后发现,利用大麻／棉水刺非织造布制备平板状滤清器的过程中,成形性较好,加工比较容易,但制备折叠状滤清器的过程中,大麻／棉水刺非织造布的折叠性较差,所形成折叠状滤清器的折叠缝隙较大,并且不容易粘接。(3)制备了浸渍层压多孔多层复合材料,并且研究过滤性能的变化。在大麻／粘胶水刺非织造布上制备一层厚度和定量分别为27.2μm,2.08g/m2的PA6纳米层后,这种基布层+纳米层复合材料的平均孔径和过滤精度变为44.3μm和16.9μm。也就是说制备的基布层+纳米层复合材料的过滤性能要比大麻／棉水刺非织造布的过滤性能好。与基布层0.82mm的厚度和131.94g/m2的定量相比,PA6纳米层具有较小的厚度(27.2μm)和定量(2.08g/m2)。粘合剂对复合材料厚度和定量的影响要远远大于PA6纳米层。而PA6纳米层对平均孔径和过滤精度的影响较大。也就是说PA6纳米层对过滤效果的影响程度大于粘合剂。利用两个基布层进行复合所形成两层复合材料的过滤性能没有基布层+PA6纳米层复合材料的过滤性能好。通过比较可以发现,三层夹芯结构复合材料具有较小的厚度、定量、平均孔径,并且具有较好的过滤性能。其中三层夹芯结构复合材料的过滤性能与5#玻璃纤维非织造布的过滤性能比较接近。基布层+PA6纳米层+粘合剂+基布层所形成的三层夹芯结构复合材料的过滤性能比基布层+PA6纳米层所形成的两层复合材料的过滤性能好。在大麻／粘胶水刺非织造布上制备一层PA6纳米层所形成的复合材料,PA6纳米层很容易与基布层分层脱落,而利用三层夹芯结构可以对PA6纳米层实现保护,并且解决了PA6纳米层与基布层之间的分层现象。将不同复合材料在不同流量下的压差进行比较后发现,含有PA6纳米层复合材料的压差与不含纳米层复合材料的压差曲线差异随着流量的增加而增加。并且纳米层对复合材料在不同流量下的压差影响比较大,静电纺纳米纤维层在提高过滤性能的同时也带来了较大的压差。随着复合材料层数的增加,厚度、定量、过滤效果和压差均增加,利用增加层数可以起到提高过滤效果的作用,但也带来了较大的压差。(4)利用大麻根部韧皮,依次经过切断、蒸煮、漂白、疏解、打浆、抄造、压榨、烘干工序后制备大麻纸,并且研究大麻纸的过滤性能。从不同打浆度大麻纸的扫描电镜照片可以发现,大麻纸的表面有不同大小的孔隙。在打浆过程中,由于ZQS2-45打浆机飞刀辊的机械作用,一些大麻纤维并没有被飞刀辊打断(或切断),而一些大麻纤维已经完全被切断。在打浆之后,在大麻纤维表面几乎看不到横节竖纹。在定量基本接近的情况下,①在打浆度增加过程中,大麻纸的厚度呈现减小的趋势,大麻纸的厚度从163μm减小到132.4μm。②在打浆度增加过程中,由于浆料中的大麻纤维不断被打断,纤维排列的紧密程度增加,使得大麻纸的紧度呈现增加的趋势,并且大麻纸的紧度从0.43g/cm3增加到0.53g/cm3。③在打浆度增加过程中,大麻纸的透气度呈现减小的趋势,大麻纸的透气度从2.748μm/Pa·s减小到0.646μm/P·s。在大麻纸的定量接近情况下,随着打浆度从38°SR增加到60°SR,大麻纸对油液中0.33μm颗粒的过滤效率和0.26μmNaCl气溶胶颗粒的过滤效率呈现增加的趋势。不同打浆度大麻纸对油液中0.33μm颗粒的过滤效率达到99.852%-99.958%,对0.26μmr NaCl气溶胶颗粒的过滤效率达到99.942%-99.973%。在相同的打浆度条件下(60°SR),①在定量增加过程中,大麻纸的厚度呈现增加的趋势,大麻纸的厚度从132.4μm增加到174.88μm。②在定量增加过程中,大麻纸的紧度呈现增加的趋势,大麻纸的紧度从0.53g/cm3增加到0.633g/cm3。③在定量增加过程中,大麻纸的透气度呈现减小的趋势,大麻纸的透气度从0.646μm/Pa·s减小到0.276μm/Pa·。随着定量的增加,大麻纸的厚度、纤维排列的紧密程度增加,透气性减小。在打浆度相同的条件下(60°SR),随着大麻纸的定量从70.29g/m2,80.35g/m2,88.50g/m2,增加到110.71g/m2,定量对液体石蜡油液中0.33μm颗粒的过滤效率以及0.26μm NaCl气溶胶颗粒的过滤效率的影响基本一致。相比70.29g/m2,110.71g/m2的大麻纸对石蜡油液中0.33μm颗粒具有较好的过滤效率。随着定量从80.35g/m2,88.50g/m2,增加到110.71g/m2,这三个大麻纸对0.26μm NaCl气溶胶颗粒的过滤效率呈现增加的趋势。其中,不同定量大麻纸对油液中0.33μm颗粒的过滤效率达到99.958%-99.975%,对0.26μm NaCl气溶胶颗粒的过滤效率达到99.964%-100%。打浆度对大麻纸中的孔隙体积的影响要大于定量的影响。打浆度越大,浆料中越来越多的大麻纤维被打断,大麻纸中纤维排列的紧密程度增加。将不同打浆度大麻纸(定量接近70g/m2)、不同定量大麻纸(打浆度为60°SR)与常用汽车机油过滤材料的性能进行比较后发现,大麻纸的过滤效率与压差均较大,这些大麻纸的过滤效率可以高达99.852%-99.975%。大麻机织物的过滤效率最小,只有3.8%,产生的压差也最小,只有6.87Pa。在相同的蒸煮、漂白、疏解条件下,将38°SR,70.49g/m2的大麻纸进行中试制备,并且将中试制备的大麻纸制备成汽车机油滤清器。通过与标准的欧三滤清器进行比较可以发现,大麻纸在提高过滤效率的同时,利用大麻纸制备的机油滤清器的成形性也较好,但与标准的欧三滤清器之间仍有一些差距。(5)对前人的压差理论进行分析后,发现前人的压差理论所用的过滤材料与本文不同,并且用途也不同,但没有清洁机油通过多孔材料的压差理论。利用大麻／棉水刺非织造布,将前人压差理论计算的压差和实验值进行比较,发现理论值和实验值之间有误差。在此基础上,通过对前人公式修正后建立自己的压差理论。将修正后的理论值和实验值进行比较,发现理论值和实验值之间的拟合效果较好,误差也较小。并且将不同打浆度(定量接近)和不同定量(打浆度相同)的大麻纸对压差理论进行实际验证。同时以纤维平均直径df=14.53μm,孔隙率s=84.99%,油液动力粘度μ=1.275×10-2Pa-s,油液密度为850kg/m3的模拟条件,对清洁油液通过大麻/棉水刺非织造布的内部流场进行二维模拟。更多还原

【Abstract】 From perspective of market researches and literatures, we know that the preparation technology of automotive engine oil filter materials is mainly concentrated in foreign countries and oil filtration materials are mainly rely on imports due to its poor filtration efficiency and short service life of our own filtration materials. In order to meet the domestic market for automobile engine oil filtration materials and to break the foreign monopoly on engine oil filter material preparation technology, it is necessary to adopt new materials or technology to develop new filtration material and filter on the basis of our own research ability.(1) Based on the research of structure and performance of commonly used automobile engine oil filtration materials, we know that these oil filtration materials are porous materials which have good pore characteristics and disorderly arrangement fiber structures. To achieve better filtering effect, the oil filtration materials should have smaller fiber diameter and pore diameter, larger porosity, smaller weight and thickness, larger air permeability, breaking strength and breaking elongation. Through a deep analysis of structure and performance changes of automobile engine oil filtration material and air material before and after use, we know that the oil and air filtration materials of automobile after use both have decreased pore diameter and air permeability, increased thickness and weight.(2) Hemp fiber, viscose staple fiber and long-staple cotton fiber are used to develop hemp/cotton (60/40) spunlaced nonwoven, hemp/cotton (60/40) needled nonwoven, and hemp/viscose (60/40) spunlaced nonwoven, respectively. Meanwhile, the41.67tex hemp yarns are used to develop hemp plain weave fabric. Then three types of hemp nonwovens and hemp plain weave fabric are used to make a comparison of pore diameter, filtration accuracy and pressure drop. And the different hemp/cotton (60/40) spunlaced nonwovens are used to research the effect of filtration area on pressure drop. The hemp/cotton spunlaced nonwoven is also used to research the filtration property and the change of different parameters in the process of filtration. The flux of experimental oil and quality of impurity particles have great influence on the pressure drop, and the pressure drop increase with the increasing of flux of experimental oil and quality of impurity particles. Through an observing the SEM figures of hemp/cotton spunlaced nonwoven after filtration, we know that the particles can be trapped on the surface of single fiber or trapped in pores between two fibers. The concentration of impurity is in a dynamic change and filtration efficiency increase as the increasing of particle diameter in the process of filtration. Compared filtration properties with5#glass fiber nonwoven, the hemp/cotton spunlaced nonwoven has higher thickness, mass per square area and pore diameter, while smaller porosity. Compared filtration efficiency with experimental valuewe know the obvious difference between theoretical value of EI、EG、ES and experimental value E, and E,<E<EG, Es<<E. The filtration efficiency of theoretical value Es can be neglected due to the smaller value Es<<E. It can be found that interception mechanism and gravity deposition mechanism play a great role in filtration. Compared with standard automobile engine oil filter, we know that the hemp/cotton spunlaced nonwoven can be easily prepared into oil filter, while it is difficult to fold the hemp/cotton spunlaced nonwoven to form a better shape due to its higher folding gap and worse bonding effect.(3) The multi-layer porous composite materials are prepared to research the filtration effect. The PA6nanofiber layer is formed on the surface of hemp/viscose spunlaced nonwoven. The thickness and mass per square area are27.2μm and2.08g/m2, respectively. The results indicate that substrate layer+PA6nanofiber layer composite material has smaller pore diameter and better filtration effect than hemp/cotton spunlaced nonwoven. Compared with higher thickness0.82mm and mass per square area131.94g/m2of substrate layer, it can be found that the PA6nanofiber layer possesses smaller thickness and mass per square area. The adhesives have a higher influence on thickness and mass per square area of composite material than PA6nanofiber layer, while the PA6nanofiber layer has higher effect on filtration effect. Compared with two substrate layer composite material, the substrate layer+PA6nanofiber layer composite material has better filtration effect. Meanwhile, the filtration property of sandwich structure composite material is similar to5#glass fiber nonwoven, which possesses smaller thickness, mass per square area, pore diameter and better filtration effect. The sandwich structure composite material has better filtration effect than substrate layer+PA6nanofiber layer composite material. While the obvious slice phenomenon between substrate layer and PA6nanofiber layer can be solved by the sandwich structure. Compared of pressure drop with different composite materials without PA6nanofiber layer, the composite material including PA6nanofiber layer has higher pressure drop at different flux of clean experimental oil. The thickness, mass per square area, filtration effect and pressure drop increase as the increasing of the layer number of composite material.(4) The hemp paper is prepared after a series process of cutting, cooking, bleaching, defibering, beating, pulp making, squeezing and drying to research the filtration properties. The obvious and different pores can be observed from SEM figures of different hemp papers; moreover, some hemp fibers are cut off by the mechanical action of ZQS2-45pulper fly knife roller while others are not in the process of beating. The typical characteristic of vertical stripes can’t be seen from the surface of hemp fiber after the beating process. On the basis of constant value of mass per square area of hemp paper, the results indicate that the thickness of hemp paper decrease from163μm to132.4μm, the compactness of hemp paper increase from0.43g/cm3to0.53 g/cm3and the air permeability decrease from2.748μm/Pa·s to0.646μm/Pa·s as the increasing of beating degree. The filtration efficiency of hemp paper for0.33um particles in the oil and0.26μm NaCl aerosol particle increase as the increasing of beating degree. The filtration efficiency of different hemp papers for0.33μm particle in the oil and0.26μm NaCl aerosol particle comes to99.852%-99.958%and99.942%-99.973%, respectively. On the basis of constant value of beating degree (60°SR) of hemp paper, the results indicate that the thickness of hemp paper increase from132.4μm to174.88μm, the compactness of hemp paper increase from0.53g/cm3to0.633g/cm3and the air permeability decrease from0.646μm/Pa·s to0.276μm/Pa·s as the increasing of mass per square area. The results indicate that the thickness and compactness increase while the air permeability decrease as the increasing of mass per square area of hemp paper in the constant value of beating degree. The filtration efficiency of hemp paper for0.33μm particles in oil and filtration efficiency for0.26μm NaCl aerosol particle both have similar change. And the filtratin efficiency of hemp paper increase as the increasing of weight. The filtration efficiency of different hemp papers for0.33μm particle in the oil and0.26μm NaCl aerosol particle comes to99.958%-99.975%and99.964%-100%, respectively. The results demonstrate that beating degree has higher influence on pore volume than mass per square area.Compared filtration properties with commonly used automobile engine oil filtration materials, we know that different hemp papers have higher filtration efficiency of99.852%-99.975%and pressure drop, while the hemp weave fabric has the worst filtration efficiency of3.8%and the smallest pressure drop of6.87Pa.On the basis of same condition of cooking, bleaching, defibering process, the hemp paper of38°SR and70.49g/m2is used to pilot preparation and making automobile engine oil filter. Compared with standard oil filter, we know that the hemp paper oil filter has better filtration efficiency and formability, while there are still some problems should be solved in the future for practical application.(5) After analysis of the predecessors’ theory of pressure drop, it can be found that the materials and purposes of predecessors’ theory are different from this paper, moreover, there is no pressure theory of cleaning oil flowing through porous material. The hemp/cotton spunlaced nonwoven is used to make a deep comparison of pressure drop between theoretical value and experimental value, which indicates that there is an obvious difference between them, so it is necessary to set up our own pressure drop theory. Compared with experimental value of pressure drop, it can be demonstrated that the theoretical value of revised equation has a better fitting effect for different hemp papers and hemp/cotton spunalced nonwoven. Meanwhile, parameters of df=14.53μm,ω=84.99%, μ=1.275×10-2Pa-s and p=850kg/m3are used to simulate internal flow field of hemp/cotton spunlaced nonwoven in the case of2D model.更多还原