Additives助剂.ppt

1、,Additives Training Course 助剂培训课程,Presented by: Process Engineering Team 主讲：工艺工程,Additives Function助剂作用,Modify paint or film properties or behavior. 改变油漆漆膜特性； Normally used at low levels.正常情况下用量低； Many different types available, also many different products within a type.很多种类型的助剂，同一类型有很多不同的产品（如流平剂）

2、Often help one property, but hurt another.常帮助改良一个特性，但伤害到另一个特性。 Most important part of formulation yet is the most difficult. 最重要的配方部份也是最困难的；,Types of Additives助剂的类型,Surfactants表面活性剂 Pigment dispersants颜料分散剂 Rheology modifiers触变助剂 Defoamers/antifoams消泡剂 Corrosion inhibitors防腐蚀剂 Adhesion improvers 附着力

3、增进剂 Photostabilizers光引发剂 Flatting agents平整剂,Types, continued助剂类型（继续）,Driers干燥剂 Anti-skinning agents and antioxidants防起皮剂和抗氧化剂 Slip aids滑爽剂 Antistatic agents and conductivity additives抗静电助剂和导电助剂 Flame retardants阻燃剂 Intumescent agents (improve fire resistance)膨胀剂 Biocides生物助剂（防霉、防腐和杀菌）,Surfactants表面活性

4、剂,Surface-active agents表面活性剂 Have groups of opposite polarity or solubility on the same molecule有相反极性的基团或可溶性体现在相同的分子结构。 They are classified based on the charge on the polar head group: - Anionics (-) 阴离子 - Cationics (+) 阳离子 - Nonionics ( ) 非离子 - Zwitterionics ,(+) (-),Surfactants,Wide range of chemi

5、stries, structures, and properties Some polymers act as surfactants A few surfactants will react in to the film due to OH groups, double bonds, etc. Wide range of applications,Surfactant Applications,Paint surface modification Wetting and solubilization Emulsification Dispersing Foaming and defoamin

6、g Conductivity and antistatic additives,Paint Surface Modification,Use surfactants and surfactant-like oligomers and polymers to reduce surface tension and make surface more homogeneous (the additive concentrates at the surface). These additives can improve flow and leveling, increase crater resista

7、nce, and prevent or reduce other defects such as dewetting, Bnard cells, floating, etc.,Paint Surface Modifiers: Silicones硅油类,Byk-300 series (300, 301, 302, etc.) - reduce s.t., improve leveling - polyether modified dimethylsiloxane copolymers. Byk-306 has been affective at reducing craters, but has

8、 also caused them. DC-200 - silicone oil Problems with silicones - can cause craters, difficult to impossible to recoat (Byk-320 probably is the most recoatable).,Different Kind of Modifiers: Various Acrylics,PBA - Polybutylacrylate Modaflow - poly(EA/EHA) Multiflow - poly(EA/EHA) Byk-358 These mate

9、rials come to the surface, but they only reduce solid surface tension slightly or not at all.,Pigment Dispersion颜料分散,Wetting湿润 Deagglomeration解聚 Stabilization稳定,Pigment Dispersants,Surfactants - wetting agents - dispersants Dispersing resins Other additives - amines - solvents,Wetting and Solubiliza

10、tion,Detergents - solubilizers and cleaning agents - linear structure with hydrophilic group at one end. Example = sodium lauryl sulfate (Tide). Wetting agents - improve pigment wetting, give better wetting of substrate surfaces, and may wet contaminants and prevent defects - tend to have a hydrophi

11、lic group between two hydrophobic chains. Examples = sodium dioctyl sulfosuccinate and Surfynol 104.,Emulsification,Emulsion polymerization - often use detergents. Dispersion and emulsification of components in waterborne coatings - wetting agents and low surface tension solvents help disperse mater

12、ials and prevent them from causing cratering or other problems.,Rheology Modifiers,Thixotropes (provide structure) - silicas - microgels - bentones “Flow control” agents (often are polymeric surfactants) Wetting agents Solvents,Defoamers/Antifoams,Often combine surfactant with fine particles (silico

13、ne and silica, for example). Many available. Use at very low levels. Usually very system dependent. Can cause craters if too much is added. Most surfactants cause foam, a few (especially the Surfynols) prevent foam.,Anti-Pop Additives,Polystearylmethacrylates (example OX-60) High MW latex Silica We

14、think that many such additives act like boiling chips and allow volatiles to come off before the film sets up.,Corrosion Inhibitors,Chromates (being phased out) and other oxidizers - passivate surface (give layer of stable oxide, protect from further oxidation). Still use SrCrO4 in repair (touch-up)

15、 primers and the primer used at Lago Alberto in Mexico (no e-coat tank). Phosphates, metaborates, phosphosilicates, borosilicates.,Adhesion Improvers,Hydrogen bonding improves adhesion to metal: hydroxyls, carboxyls, amine groups. Epoxy resins have hydroxyl and ether groups - bond to steel and inter

16、act with other molecules in the coating. Some surfaces, especially plastics, are difficult to adhere to because they have low surface tensions and few or no polar groups. Tie coat or adhesion promotor is necessary - usually thin layer of chlorinated polyolefin or chlorinated rubber.,Photostabilizers

17、,UV absorbers Excited state quenchers Antioxidants Hindered amine light stabilizers Pigments (especially to protect lower layers). One reason why good hiding by basecoats is so important.,Big Problem with Photostabilizers,They do not stay where we want them! Ford research shows that they often migra

18、te to the basecoat on application and baking and/or diffuse out of the clear on weathering. The degree of retention depends on the chemistry of the clearcoat.,Flatting Agents,Added to reduce gloss, improve sandability. Usually silica or some other particulates, although E.D. uses an organic flatting

19、 agent. Auto companies want as high a gloss as possible, so rarely needed in automotive topcoats or even primers.,Driers,Driers are organometalic catalysts. They accelerate oxidative crosslinking of drying oils (such as linseed oil) and alkyds. They are oil soluble salts of metals such as Co, Mn, Pb

20、, Ca, La, Fe, and Zr. They often are used as a mixture of salts (for example, Co and Mn as surface driers, Zr as a through drier).,Anti-Skinning Agents and Antioxidants,Anti-skinning agents reduce the rate of surface oxidation and, therefore, reduce the curing of the top layer of an alkyd or linseed

21、 oil paint or stain. Example = MEK oxime. Antioxidants are used to prevent or reduce oxidative degradation. The driers that catalyze cure also catalyze degradation, so metal complexing agents are used to tie up the metal.,Slip Aids,It often is useful to make a paint surface slippery so that the coef

22、ficient of friction is low, scratch resistance is improved, most things will not stick to the surface (blocking resistance is high), etc. Waxes often are used for this purpose as are silicones and fluorinated surfactants. Slip aids can cause repair and recoat problems.,Antistatic and Conductivity Ad

23、ditives,Conductivity/resistivity of solvents and paints are controlled for a variety of reasons. Antistatic agents are added to hydrocarbon solvents to prevent build-up of static charges that could give sparks and fires/explosions. Solvents, salts, and surfactants can be added to paints to give the

24、correct resistivity for good electrostatic spray application. Occasionally, antistatic properties are needed in coatings on electrical equipment.,Flame Retardants,Antimony oxide (Sb2O3) is a white pigment that is used in fire retardant coatings. When a combination of antimony oxide and a chlorinated

25、 or brominated polymer is heated to high temperature, combustion products are generated that suppress flame propagation.,Intumescent Agents,Certain coatings foam and form an insulating layer when heated to a high temperature as in a fire. PPGs product PITT-CHAR is an excellent example. Such coatings

26、 employ heat-activated foaming or blowing agents.,Biocides,Bug Killer Additives Bactericides - control bacterial growth in paint can or e-coat bath. Fungicides - minimize mildew growth on the paint film.,Solvents as Additives,Can reduce surface tension of paint for better wetting, defect reduction d

27、uring flash (can act as fugitive “surfactant”). Non-water miscible solvents such as mineral spirits in w/b coatings give coalescence and reduce defects (oil on troubled waters). Can act as defoamers, pop-reducers (examples: 2-ethyl hexanol, tributyl phosphate). Slow water-miscible solvent (humectant

28、) can keep w/b surface open.,Coalescing Solvent in Waterborne Coatings,Plasticizes polymer/pigment mixture. Lowers Tg of total system. Lowers minimum film forming temperature (MFT). High Tg polymers are difficult to coalesce (high MFT) - addition of sufficient coalescing solvent to give low temperat

29、ure film formation may mean a very slow dry and soft (possibly tacky) surface.,Coalescing Solvents,Characteristics of good coalescing solvents Low evaporation rate. Good solvent for resin(s). Greater tendency to be in polymer phase than in aqueous, i.e., greater resin compatibility than water compat

30、ibility.,Resins as Additives,Polyacrylates - Modaflow (poly EA/EHA), PBA - flow control agents and surface homogenizers. Surfactant-like polymers - flow control agents, crater preventers (powder clear FCA probably the best example) Epoxies - adhesion. Various acrylics (especially with imino groups) - pigment dispersants. Very small amounts of very high MW resins can improve atomization (act like ball bearings?).,Recommendations,When you have a problem or defect, make sure that you understand it before you