| At present,diesel engines are widely used in commercial transportation,engineering machinery and agricultural machinery.With the advancement of mechanical processing technology,the performance of diesel engines has been greatly improved,and the requirements for oil quality have become increasingly strict.However,the conventional single-layer diesel filter paper products cannot meet the requirements of the high-pressure common rail fuel injection system because of their poor pore structure,strength performance and filtration performance.In order to improve the performance of single-layer diesel filter paper,this project took softwood bleached kraft pulp(SWBK)as raw material to prepare microfibrillated cellulose(MFC),which was sprayed single-layer diesel filter base paper(substrate)to obtain composite diesel filter base paper(composite base paper).The effects of different fiber diameters and drying methods on the performance of cationic microfibrillated cellulose(C-MFC)composite base paper were discussed.And the performance of the composite base paper prepared by acetylated microfibrillated cellulose(A-MFC)and C-MFC was compared.Firstly,the effect of C-MFC with different fiber diameters on the performance of the composite base paper at the same spraying amount(C-MFC spraying amount of 3.5 g/m2)was analyzed.The results show that C-MFC can be successfully prepared by the pre-treatment combined with high-pressure homogenization,and the average diameter of C-MFC decreased from 154.52 nm to 68.26 nm with increasing homogenization pressure.Compared with the blank sample,the average pore diameter of composite base paper was reduced from 21.27 μm to 14.10 μm,and the maximum pore diameter was reduced from 64.20 μm to 38.00 ym.And the pore size distribution of filter base papers was more uniform.The spraying of C-MFC could significantly improve the strength properties of diesel filter base paper.Prepared with C-MFC product which was obtained at a homogenization pressure of 70 MPa.The tensile index and burst index of the composite base paper were increased 61.16%and 124.60%,respectively compared with the control sample.Secondly,the effects of two drying methods(air drying and vacuum cold drying)on the performance of C-MFC composite base paper were discussed.The results show that compared with air-dried C-MFC composite base paper,vacuum cold-dried composite base paper had better pore structure,including smaller average pore diameter and maximum pore diameter,higher air permeability,and more uniform pore diameter distribution,while its strength performance was weaker than that of air-dried composite base paper.In order to meet the technical requirements of diesel filter paper with air permeability greater than 45.00 L/m2/s,the maximum spraying amount of C-MFC on the surface of air-dried composite base paper was 3.5 g/m2.At this time,the average pore diameter and the maximum pore diameter were 14.10 μm and 38.00 μm,which were reduced by 33.71%and 40.81%compared with the blank sample.However,the spraying amount of C-MFC on the surface of the vacuum cold-dried composite base paper could reach 6.5 g/m2,and the average pore diameter and the maximum pore diameter were 6.86 μm and 15.60 μm,which decreased by 67.75%and 75.70%respectively.Meanwhile,the tensile indices of air-dried and vacuum cold-dried composite paper increased by 61.16%and 46.30%,and the burst indices increased by 124.60%and 93.42%respectively.Finally,the influence of spraying A-MFC on the properties of composite base paper was studied,and the results showed that with the A-MFC spraying amount increasing to 7.5 g/m2,the average pore diameter of A-MFC composite base paper was gradually reduced to 8.32μm,and the maximum pore diameter was gradually reduced to 17.20 μm.Compared with C-MFC,A-MFC composite base paper obtained a higher breathability,when the spray volume reached 7.5 g/m2,which can still meet the technical requirements of diesel filter paper air permeability,successfully alleviated the contradiction between air permeability and pore size of MFC composite base paper after air drying. |
