胶合板用改性脲醛树脂预压强度的研究

163Vol.16No.3CHINAWOODINDUSTRY20025May2002:2001209220:(19712),,,,(,210037):PVA,,;PVA,;,;;;:(MUF);:TS653.3:A:100128654(2002)0320012203StudyonPrepressingIntensionofModifiedUFResinforPlywoodHANShu2guang,LIUQi2ming,DUYi2cheng(CollegeofWoodScienceandTechnology,NanjingForestryUniversity,Nanjing210037,China)Abstract:Theureaformaldehyde(UF)resinforplywoodwasmodifiedwithmelamineandpolyvinylalcohol(PVA).TheeffectsofmodifiedUFresinmakingsincludingfinalmolarratio,quantityofmelamine,PVAandfinaltemperature,andpropertyindexesincludingviscosity,solidcontentandfreeformaldehydecontentonprepressingintensionofassembledmatwerestudied.Re2sultsshowedthatlargerquantitymelaminehadnoadvantageofimprovingtheprepressinginten2sion,andPVAcouldhelptoincreaseoriginalviscosityobviously,buttheoriginalviscositycouldnotdeterminetheprepressingintension.Thehightemperaturesoffinalreactionandshortcuringtimeweregoodfortheprepressingintension,butprepressingintensiondecreasedwithsolidcontentofresinincreased.Thelowfreeformaldehydecontenthadlittleeffectonprepressingintension.Keywords:Melamineurea2formaldehyderesin(MUF);Prepressingintension,,(),,,,,(),,,,(2530,90),,,,,,11.1,1.7mm,11.2(1):,1.0MPa,40min;5h,110,1.0MPa,4min(2)(,211Tab.1TheproportionofmodifiedUFresinanditsfinaltemperatureFU()%PVA%1.415.01.50901.312.51.25801.210.01.00701.17.500.75601.05.00.5050):1.0MPa,40min1.3GB9846.9288,GBT14074.10293,1GBT14074.3,5,7,16293;GBT17657219991Fig.1Specimenfigureandsize22.1Origin(2),1.01.1,;1.11.4,1.01.1,,(36h),,PizziA[1]11.11.22Fig.2Relationofmolarratioandprepressingintension(1.1),,,,,,[2],2.23,7.5%10%12.5%15%()3Fig.3Effectsofquantityofmelamineonprepressingintension2.3PVA(PVA),,4,PVA,PVA4,PVA,pH4PVAFig.4EffectsofquantityofPVAonprepressingintension2.45607080,,,,,2.5(6),31163200255Fig.5Effectsoffinaltemperatureonprepressingintension,,,,6Fig.6Relationofresinviscosityandprepressingintension2.67,,,,,7Fig.7Relationofresinsolidcontentandprepressingintension2.78,,,,,,2.89,0.25%,;0.25%,,8Fig.8Effectsofcuringtimeonprepressingintension9Fig.9Effectsoffreeformaldehydecontentonprepressingintension31);PVA;PVA,;2)(0.8MPa,),;;(0.5%),,:[1]PizziA.TheoryandPracticeofthePreparationofLowFormaldehydeEmissionUFAdhesives[J].Holzforschung.1994,48(3):254261.[2]CombsEP.RubberAge[J].1965;7:8694.41May2002CHINAWOODINDUSTRYVol.16No.3