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QCM DIPPING GRADE PLASTISOL
SAFETY: QCM Company is one of the first Companies to manufacture Plastisols using non-Orthophthalate Plasticizers. The proprietary plasticizers that we use are metabolized in the body (pass through) unlike Orthophthalate plasticizers, which are suspected of accumulating in the liver and kidneys (suspected carcinogens in lab animal studies). We use only the safest ingredients (no heavy metals or formaldehyde) and have for the past 30 years. We also make higher durometer grades (P8001 series) for high endurance maintenance coatings. Our primer A1104 has outstanding adhesive properties to metals. For molding, see our P6003 base. See our Playground Coating Data Sheet, for an excellent range of high quality plastisols used in the coating of metal Playground Structures. For Air-dry coatings see CPVC data sheet. This is a solvent based system that is completely different (main point is: it is AIR DRY) and gives much thinner coatings than is possible with regular plastisol. Also see Urethane based coatings MF-208 and MF-231. Call us to discuss your application and requirements at 1-800-321-0170 or e-mail us at Dave.Musick@qcminks.com . see the procedure following: COATING METALS WITH PLASTISOLS PLASTISOL is a heat cured protective coating. A well controlled industrial oven is normally required to effectively coat metals with plastisol. There will also be needed: dipping tank(s) and testing time to establish both dip and cure times for each part to be coated. PREPARATION OF PARTS TO BE COATED FOR G.S.A. customers: See Process Instruction 8030 941 525A. Solvent wipe, vapor degrease, sand or sandblast metal to insure a reasonably clean surface. In instances where metals have been in and around acid and salt solutions, it is a good idea to water rinse first as most salts are not readily soluble in solvents. If there is a possibility of aluminum parts being distorted by grit blasting, chemical cleaning may be used:- immerse the parts at 150 deg. F for 15 minutes in a bath of: Sodium Dichromate 1.0 pbw ( parts by weight) Sulfuric Acid (1.84 S.G.) 8.4 pbw Water 90.6 pbw. Rinse in hot water at 150-180 deg. F and dry 10 mins. in hot air at 140-150 deg. F. APPLY AND DRY PRIMER CAUTION: PRIMER IS FLAMMABLE! CONTAINS SOLVENTS. SEE MSDS. PLASTISOLS do not stick to metal without a primer. ( If adhesion is not needed for a given application this step may be eliminated.) Primer required is QCM part number A1104. Primer may be applied by dipping, flow coating, brushing or spraying. Dipping and flow coating tend to give the best results because they provide the most consistent film thickness and maximize adhesion to the plastisol. DO NOT DIP HOT METAL PARTS INTO PRIMER BATH - EXPLOSION HAZARD! Dip for 1 second and immediately withdraw part. Do not coat areas of metal where plastisol is not to be adhered, because primer is very effective and plastisol will have to be mechanically stripped from these areas (with great difficulty). Solvent evaporation from primer tanks should be adjusted for, with the periodic addition of PRIMER THINNER. See Data Sheet for A1104. Where parts are going to be preheated prior to dipping into the plastisol, a 1 hour air dry of the primer is sufficient. If parts are not being preheated, allow a minimum of 24 hours dry to ensure that all the solvent has evaporated from the primer film. When Preheating Primed Metal Parts: Do not overbake primed metal - the priming action of the primer will be destroyed by excessive preheating cycles - see A1104 primer NOTE: While establishing cure times and dip times, it is advantageous to experiment with unprimed metal parts first until a clear time/processing procedure has been established. During this experimental stage, the plastisol can be easily stripped from the metal. Once the procedure is clear, primer can safely be applied for permanent adhesion. PREHEAT METAL PARTS - DIPPING APPLICATION Coating thickness of the plastisol can vary from .01" (fast, single dip with 350 deg. F part) to .125" (slow dip, possibly double dip with extra hot parts 375-400 deg. F). Plastisol coating thickness on the finished part will be directly related to: 1) The gel temperature of the plastisol (most plastisols gel at around 200 deg F). 2) The temperature of the part when it is dipped into the plastisol (variations in the length of time between removal of the part from the oven and dipping in the plastisol will result in variations in ultimate coating thickness). 3) The mass of the hot part (small parts will quickly cool to below the gel temperature of the plastisol resulting in low film thickness, while larger parts will hold heat longer and gel on a greater amount of plastisol). TIP: Normal preheat temperature is 350 - 375 deg F. However, when greater film thickness is desired on thin parts or on thin projections of larger parts, a short preheat (5 minutes) at 400 - 450 F. followed by a short dip (5-20 seconds) and a uniform withdrawal rate will sometimes eliminate the need for double dipping. 4) The rate of heat transfer of the particular metal. Aluminum and steel are good conductors of heat and Hi Build coatings are relatively easy to obtain with preheat temperatures in the 350 - 375 deg F. range. Lead and some of its alloys are rather poor heat conductors. To get a reasonably heavy build on these, much higher preheat temperatures may be necessary. Preheat temperatures (not cure) of up to 600 deg F. have been reported to give good results. APPLYING PLASTISOL While flow coating and spraying of PLASTISOLS are feasible, the most common method of applying PLASTISOLS is dipping the hot parts into a pail or tank of plastisol. Two methods will be discussed - HOT and COLD withdrawal of parts. HOT WITHDRAWAL This method is used where it is mandatory to minimize drips or runs. It best lends itself to parts of relatively simple straight line configuration. EXPLANATION: If the metal part is withdrawn from the plastisol while the temperature of the metal is above the gel temperature of the plastisol, gelation will be occurring at the same time that the part is draining. If the part is withdrawn too rapidly, gelled-in "runs" will occur. Too slow of a withdrawal rate will result in the top of the part being properly gelled, and the bottom being "un-gelled" on the surface. Gelled areas have a dull appearance while "un-gelled" areas will be wet, glossy and still dripping. The proper withdrawal rate should be established for each part of a given design being coated. COLD WITHDRAWAL The idea behind this method is to leave the part in the plastisol until the metal temperature is below the gel temperature of the plastisol. Then, withdraw the plastisol coated part and allow to drain completely before placing it in the oven for cure. This method usually results in more pronounced drips on the bottom of the part (these can be trimmed off) but is probably the best method for more complex shaped parts. DRAINING The bottom of the parts that are draining should be kept relatively close to the surface of the plastisol in the tank or drip pan to minimize the formation of bubbles that result when the plastisol drips onto the surface of the plastisol in the tank from greater distances. CURING PLASTISOLS It is not necessary to cure PLASTISOLS a definite period of time as is the case with baking enamels, epoxies, etc. To cure a plastisol you need only get the material up to 350 F. for a couple minutes. Oven settings of 350 - 400 F. work fine. Thin coatings of plastisol on thin pieces of metal can be cured in as little as 3-4 minutes. Cure, and therefore the best properties, is evidenced by slight smoking and glossiness of plastisol surface. * Smoke is merely high boiling liquid vapors with a flash point well above the processing temperatures and does not present a fire hazard. These vapors can be easily condensed back to liquids by venting through some aluminum vent pipe with a few condensing vanes. For large volume applications a "smog hog" or equivalent may be required. Consult with your State and Regulatory Organizations for specific requirements. In the absence of any special equipment to collect these vapors, it is important that you vent vapors to the "outside". Long term effects of breathing vapors is not known...so better to be on the SAFE SIDE. REPAIR OF DAMAGED COATINGS: Best repairs of damaged plastisol coated parts are done by applying fresh liquid plastisol to the defective area and fusing it at the required temperature to effect cure (see above). FOR thicker areas of worn plastisol, consult QCM company for the availability of a thickened plastisol coating that can be brushed on in thicker layers and then heat cured (P7002-TH- products). Also available from the manufacturer (QCM COMPANY) is an air dry patch coating designated as CPVC-4 products, which can be brushed on and air dried. CALL Technical Services ( 1-800-321-0170) for Technical help. COVERAGE OF PRIMER vs. PLASTISOL Much less primer is normally required than plastisol. The primer is effective if coated at .002" (wet) and is actually not recommended in thicker coatings (this could trap solvent and contain uncured resin; later during heat processing the solvent will boil and cause bubbling). Two mils wet will dry down to a thickness of 0.4 to 0.5 mils dry. Usage rate for A1104 primer: 800 sq. ft. per gallon Typical coating thickness of PLASTISOLS is about 30 - 60 mils (1/32" to 1/16"). See commercially applied tool handles as an example. Coverage at 30 mils is prox 50 sq. ft. per gallon. At 15 mils (typical thin coating) coverage would be 100 sq. ft. per gallon. 100 sq. ft. per gallon is the same as 2.454 square meters per liter. Obviously then, the primer is used at a much lower rate, e.g. one tenth as much primer is used as plastisol, depending on the plastisol coating thickness. SAFETY PRECAUTIONS: As with any chemical, always read Material Safety Data Sheet before use. STORAGE OF PLASTISOL Store plastisol in a dry environment, between 60 and 80 degrees F away from heat and sunlight. Keep containers tightly sealed when not in use and cover dip tanks when not in use. SHELF LIFE Twelve months guaranteed from date of purchase when stored as above. for more info: e-mail us at Dave.Musick@qcminks.com
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