WATER-BASED BINDERS USED IN PROCESS FOR MAKING AUTOMOBLE FILTER PAPER

JOURNAL OF2004 AprilTIANJIN UNIVERSITY OF SCIENCE AND TECHNOLOGYVol.19 SuppWATER- BASED BINDERS USEDbinder composition. The resulting impregnated filterIN PROCESS FORMAKINGpaper has the necessary balance of permeability andother physical property.Such filters anAUTOMOBLE FILTERPAPERmanufactured with the material and chemicals whichhave no impairing to the environment by emittingHua Li , Jian Huvolatile solvents.Huaiyu Zhan，Yi WangState Key Laboratory ofPulp & Paper Engineering,2 EXPERIMENTALSouth China University of Technology，Guangzhou,510640, China2.1 Raw Materials The hand sheet of filter paper ismade from 70% of sisal pulp and 30% ofABSTRACTpolypropylene . The basic weight of the base paper is105(+5) g/m2.A method for making a automobile filter whichPhenol-formaldehyde resin was supplied by Chinaincludes impregnating a filter paper with aWeapon Industry No.53 Institute.cross-linkable binder composition is discussed in thearticle. The water-based binder comprises a latex2. .2Synthesis of Bindercontaining 80 wt% acrylic acid in the latex solids,2.2.1 Modifed PVAcand 20 wt% melthyl methacrylate, the binder alsoEmulsifier, initiator,， vinyl acetate (VAc) andcontains 5 parts of a cross-linking resin per 100deionized water were added to a four-neck flaskweight parts of latex solids and 5% parts of catalystequipped with thermnal coupler and stirer.Thefor the cross-linking resin based on the weight of thereactor was kept at a designed temperature using across-linking resin. 4 wt% water-based polymerwater bath. melthyl methacrylate (MMA) and acrylicemulsion, on a solids basis,which is used toacid (AA) with set amounts were then added to theimpregnate filter paper and rigidify it Suchreactor under stirring. The polymerization was lastedimpregnated filter paper has good dry and wet tensilefor six bours.strength and stiffness. The method has no impairingThe latex had the following formulation, in parts byto the environment.weight:KEYWORDS: water-based binder， filter paper,demineralized water: 125strength propertyvinyl acetate: 65melthyl methacrylate: 30Article ID:1672- -6510 (2004) supp -0212 -03acrylic acid: 5emulsifier: 141 INTRODUTIONinitiator: 0.62.2.2 Modified PAAThe paper used as the filtration medium forEmulifier, initiator, AA and deionized water wereautomotbile filters has been traditionally treated withadded to a four-neck flask equipped with thermalcoupler and stirrer.The reactor was kept at aalcohol solution of phenolic resins. This has beendesigned temperature using a water bath. MMA withdone to improve the paper's strength properties anda set amount was then added to the reactor underallow it to be pleated in an accordion-like shape andstirring. .The polymerization was lasted for threeto hold the shape when the paper composite is cured.hours.With the onset of greater concern for environmentalquality，the filter manufactures have requested paperdemineralized water: 800suppliers to provide a free or loweracrylic acid: 80formaldehyde containing impregnated sheet thatmelthyl methacrylate: 20holds its pleat, and meet all of the requirements foremulsifier: 5filters. The paper suppliers have, in turn, requestedinitiator: 1.0resins suppliers to supply a water-based binder that2.3 Ilmpregnationprovides performance at least comparable to that ofThe aqueous binder composition was preferablyphenolic aldehyde resins.2This study is directed to filters generallyadmixed with 5% cross-linking agent (based onencompassing air, fuel, oil filter media such as filter中国煤化工T)r the cross-linkingegnate fiIter paper.paper impregnated with a cross-linkable aqueousYHC N M H G resin composition.212-Vol.19 SuppJourmal of Tianjin liniversity of Science and Technologysolids, prior to impregnation, were adjusted withwater and alcohol respectively to a solids content of2.4 Physical property testabout 4%. The filter base paper was impregnatedThe physical properties of the three samples werewith binder compositions at 22(+2) wt.% dry coating.tested according to the standard methods.Each impregnated sheet of filter paper was dried for3 hours at 550C and cured for 20 minutes at 1000C.3 RESULTS AND DISCUTIONSample A: the filter paper impregnated with alcoholsolution of a phenol-formaldehyde resin.3.1 Physical property of the impregnatedSample B: the filter paper impregnated withpapercross-linkable aqueous binder of VAc/MMA/AAIt is known that synthetic fiber has lower interfiber .copolymer.bonding. By adding resin, which has good gluability,Sample C: the filter paper impregnated withcan reinforce the bonding between fibers, and thencross-linkable aqueous binderof AA/MMAincreases the tensile strength and burst of filter paperas result.Table 1 Physical properties of the impregnated paperSampleBasic WeightPickupBulkBreakingBurst IndexLengthg/m2%cm'/gKPa.m/gkmBase paper1055.9510.3000.33A127.7820.736.3393.7203.75B123.66 .21.466.3083.4133.93C133.6522.505.8663.8824.11. It can be seen fom Table 1 that the paper treatedBy adding methyl methacrylate, the interfacial effectwith cross-linkable aqucous binder displays similarbetween fiber and resin is enbanced, and then thestrength properties as the control treated withpaper treated with such resins can achieve excellentphenol-formaldehyde resin.Though showing. astrength properties.月slightly lower bulk, the use of water-based AA/MMAresin favorably gave higher breaking length and burst3.2 Tensile strengthindex. It can be explained by two factors. Firstly,with the use of hard monomer，the cross-linkableaqueous binders have good strength ptopertiesintrinsically. Secondly, interfacial phenomena, whichis caused by the space-charge effect of polar groups.For example, the tructure unit of PVAc resin is asfollow:十- CH2- CH--KN/m 300=C一CHsAnd VAC-MAA copolymer's structure unit isnlCH,SampleA ! SampleB SampleC十CH- CHHHCH2- C士-中国煤化工0- CH,MYHCNMHG213 -Juirnal of Tianjin University of Science and TechnologyVol.19 Suppwater-based PAA resin, is even 6.49% higher thanthat of sample A treated with phenol-formaldehyde2.5resin.The wet tensile strength was tested afterimpregnating the filter paper in deionized water forhalf an hour. It represents the water resistance of the1.5filter paper. It can be seen from Fig 2 that suitableKN/mcross-liking agent has been found to provide thedesired degree of cross-linking of the basic PAAlatex and render it resistant to water. Wet tensile via0.5dry tensile is above 41.85%.SampleA SampleB SampleC3.3 StiffnessStiffness is one of the most important factors of theFig.2 Wet lensilefilter for holding its shape. The stifness values of theflter paper impregnated with different resins areFig.1 shows the dry tensile values of filter papershown in Fig.3-3. We can see from Fig.3 thatimpregnated with different resins. With the use ofmodified PAA resin has more profound effect on thehard monomer methyl methacrylate,[3] the modifiedfilter sifness than phenolic esin and modifedPVAc resin and modified PAA resin have good dryPVAc resin, which may be related to the degree ofstrength properties and is comparable with phenoliccross-liking.resin. The dry tensile value of sample C, treated with2.5r21.5|mN, m1nlFig3 Sifness after Curing6.49% and 21.95% higher than those of control4 CONCLUSIONStreated with phenolic resin respectively, thoughthe wet tensile strength is 13.06% lower.4.1 The cross-linkable water based PAA resin couldimprove the strength properties of the filterREFERENCESmedia substantially. For instance, when pickupof the resin is 22.50% (based on base paper), the. United States Patent 4,623,462United States Patent 5,244,695breaking length and burst index increase aboutLi Hua, Hu Jian, Wu Jiaoping and Zhan Huaiyu, Study on12 times of those of base paper.the Synthesis of Copolymerization Emulsion of Vinyl4.2 The cross-linkable water based PAA resin couldAcetate and Methyl Methacrylate and Its Strengtheningprovide performance comparable or superior toEffect to Paper, Paper Science & Technology 2002, 21(2):that of phenolic resin. The dry tensile strength27-30and sifness of PAA treated filter paper are中国煤化工MHCNMHG.214.