ASA,AKD,树脂中粒径大小，粒度分布检测方案(激光粒度仪)

AN136Particle Size Distribution AnalyzerApplications NotePaper Coating Chemicals AN136Particle Size Distribution AnalyzerPaper Coating ChemicalsApplications Note PAPER COATING CHEMICALS Paper is manufactured from wood fiber slurries， fillers， sizing agents， andcoatings. Sizing agents are used to provide resistance to the absorption ofmoisture or to eliminate ink feathering and bleed through. Selection of thespecific sizing agents， fillers or coatings will depend on the final applicationfor the paper. Alkaline Papermaking Alkaline papermaking refers to theformation of paper sheets from fiberslurries having a pH generally in therange of 7 to 9. Alkaline paper sheetstypically contain some form of calciumcarbonate filler， which would dissolvein the conventional acidic conditions.Water repellency in alkalinepapermaking operations is usuallyachieved with synthetic sizing agentssuch as alkenylsuccinic anhydride(ASA) or alkylketene dimmer (AKD). ASA Sizing Agents The active ingredient of ASA is an oilymonomer. The product is almostalways delivered as a light amber oilthat must be kept very dry untilemulsification. ASA is added to theprocess in the form of an aqueousemulsion， in which the stabilizer isusually cationic starch and a smallamount of surfactant to aid inemulsification. The key goals in using ASA are toavoid hydrolysis and distribute it wellin the process. Hydrolysis is minimized by preparing the emulsion as late aspossible， usually only seconds beforethe material is added to the thin stock.Particle size analysis can showwhether one has achieved the desirednarrow size distribution of droplets，usually with an average size near orbelow one micrometer. Because of theinstability of the emulsion， testingmust be done at the point of use. Horiba's LA-300 has proven to beextremely popular for this applicationbecause of its portability， fast analysistimes， and ease of use. The exampledata shows an ASA emulsion tested in the field. The small size and lowweight of the instrument allowit to be transported to variouslocations for routine testing ofthe emulsion preparationequipment. ASA emulsion Median： 0.885um D(10%)：0.598pm D(90%)： 1.345pm Mean： 0.938um AKD Sizing Agents Acidic Papermaking AKD is synthesized from fatty acids. The most common form is a waxy solidmaterial dispersed as small particles ina solution that contains a stabilizer，usually a cationic starch. Liquid formsof AKD have recently become available.Though slightly less efficient as asizing agent than the waxy form， theliquid product does not make thepaper as slippery. For papers manufactured with a pH inthe acidic range， rosin sizing agentsare used， either an emulsion of therosin acid or a saponified rosin soap.The word "rosin" refers to a series ofchemicals isolated from the "tall oil"that is produced during kraft pulping ofsoftwood species. Rosin acids aretacky solids at room temperature. Tobe used effectively in a paper machine，the rosin can be melted and emulsifiedin water， usually with a stabilizeradditive. An alternative is rosin soap，which is formed by saponifying therosin by addition of base so that itbecomes soluble in water. The rosinsoap is delivered to the mill as a liquid.In either case， the final emulsion canbe tested for particle size to determineits stability and coating properties. AKD is used for hydrophobization ofpaper， especially when made underalkaline conditions. AKD is widely usedfor liquid containers， ink-jet printingpapers， and many other grades ofpaper that need to resist water over along period of time.Because AKD isreceived at the paper mill as a ready-made， milky emulsion， it can be a veryconvenient product to use. Also， thelower reactivity of AKD， compared toASA， means that the papermaker hasmore flexibility on where to add it. Inthis case， it may be less necessary totest the product at the paper mill，although process control in the centralmanufacturing facility is still required.Horiba's LA-300 may still be more thansufficient， but the LA-930's greaterrange and lower limit may provide Horiba LA-930 Particle Size Analyzer Fillers And Coatings A number of additives are used inpapermaking， from calcium carbonateused as a filler to a variety of mineralsand latex added to the surface coatingto improve brightness， gloss andprintability. The selection of theadditive depends on the surface finishrequired and the final use of the paper.Colored papers require the addition ofa pigmenting agent. The particle sizeof all these materials affects surfacefinish， color strength， and mechanical properties. Smaller particle sizeprovides a smoother surface andbetter coverage per unit of additive. Measurement of particle size can takeplace at the point of manufacture，such as a kaolin mining plant orpigment factory， or upon receipt at thepaper mill as a final check. Theexample below shows kaolin tested onthe LA-930. The size range of interestwill dictate the model most appropriatefor the application. Kaolin Median： 0.638pm D(10%)：0.427pm D(90%)： 1.052um Mean： 0.701pm Copyright 2004， Horiba Instruments， Inc. For further information on this document or our products， please contact：Horiba Instruments， Inc. 17671 Armstrong Ave. Irvine， CA 92614 USA (949) 250-4811 www.horiba.com HORIBA A number of additives are used in papermaking, from calcium carbonate used as a filler to a variety of minerals and latex added to the surface coating to improve brightness, gloss and printability. The selection of the additive depends on the surface finish required and the final use of the paper. Colored papers require the addition of a pigmenting agent. The particle size of all these materials affects surface finish, color strength, and mechanical  properties.  Smaller particle size provides a smoother surface and better coverage per unit of additive.