Polyurethane Foams Self-Study Notes by Tom Veatch SAFETY FIRST: Used for decades in major industries BUT: Avoid overexposure causing irration and sensitization. Vapor pressure is 720x less than water. Odor is not a good indication of exposure. Limit to 1ppb for 8Hr days, 5ppb for 15min, 20ppb hard max. Provide local exhaust ventilation. Wash Hands and Clothes. Use PPE: nitrile/butyl rubber gloves, eye/face shield for splashing. OSHA says SA (Supplied Air) for respiratory protection. Read the MSDS, supplier resources, and trade association guidance. INTRODUCTION: Polyurethane foams mix two mutually-reactive organic chemicals into a low-viscosity liquid mixture that becomes a bubbly liquid by gas generation, and then becomes a solid foam by polymerization. ORGANIC CHEMISTRY: Organic Chemistry could be called Carbon Combinatorics. Or HCON combinatorics. O Chem is about simple patterns in plastics, and slightly more complex patterns in DNA, protein, and life, which are mostly all about hydrogen (H) and carbon(C), somewhat about oxygen(O) and nitrogen(N), and to a far lesser extent anything else. Four or so simple rules give me most of what I know so far for reasoning about organic chemistry: * Every stable carbon has slots for four attachments satisfied by a link to an H, C, O or N. In C-C one, and in C=C two, slots on each C are filled by the other C. So there can be double bonds too. * Nitrogens need three slots filled, and * Oxygens need two slots filled. * Hydrogens and each of the others fill one slot for its attached other in a molecule. Puzzle pieces made of these parts, and following those four rules, can arrange themselves into sequences of the same or similar things over and over making polyX's or DNA's, proteins, plastics etc. We start, then, with a single carbon alone, that is to say we don't even mention any more because we already know that of course it has four slots and so those will naturally have four hydrogens on it, this is the simplest of hydrocarbons, it's called methane. Now you must look at once, twice, three times, and then memorize the following molecule names in the following order: * METHANE(1), ETHANE(2), PROPANE(3), BUTANE(4), PENTANE(5), HEXANE(6), HEPTANE(7), OCTANE(8), etc. these are straight chains of 1-8 carbons with as-needed added hydrogens to fill the unoccupied slots. The numbers for each name are in Greek counting from 5 up. * BENZENE: a hexagon or ring of six carbons with alternating double bonds and a single hydrogen off each one thus filling all four slots of each C. * TOLUENE: a benzene ring with a methane attached anywhere. Obviously all these like to light up. I mean, if there's any double-oxygens nearby and any bonking into one another with any kind of energy, then every nearby pair of hydrogens will split off one of the oxygens making an H2O, leaving behind C's each to grab a whole O2 and make a CO2. Plus heat, because they all would frankly prefer the outcome by a lot: they physically accelerate after. This is called fire, also petroleum or gas or fuel, since in our highly oxygenated atmosphere you just need a tiny bit of extra heat next to some of hydrocarbons and some O2's to make the reaction spark off and make a chain reaction until everything, whatever it used to be, is used up, leaving only CO2 and H20, that's called a full clean burn. Now you know enough to fill your tank and send money to Saudi Arabia. And we're about to get to cushy foams, which is to say polyurethane. Almost there, memorize just a few more names!: * -OL: a molecule ending in OH: alcohol/glycol/sorbitol (HOH/H2O) * POLYOL: has two or more -ol's, OH groups, on its periphery. Say, what are diols and triols? 2 and 3 OH's. * ISOCYANATE: is an NCO (N-C=O) * DIISOCYANATE: Two NCO's (N-C=O, O=C-N) around some root. OCN-R-NCO * URETHANE: is an R-NCO-R chain popped in the middle of an OH, as in: H R-N-C-O-R O (Like an amide but with an extra O, I'm told.) As you go along from here, you will surely encounter lots more O Chem names and you can look them up then, if you like, and make your own notebook of formulas and drawings for chemicals and their names. But for now, enough. Because at this point you know enough, you have the intellectual ammunition, today, to prove to yourself that di-ols can link up between diisocyanates making chains by giving each edge OH of a diol to each edge NCO of a diisocyanate to combine into a urethane in the chain, of unlimited length. Right? With chains of OH-linked roots, we have n each of HO-R1-OH (polyol) + OCN-R2-NCO (di-isocyanate) -> OCN-R2-U[n]-NCO where U is a urethane, namely NH-[C=O]-O-R1-O-[C=O]-NH-R2 and there are n of them. n>1 means poly urethane. In this case one diol polyol contributes H0-R1-OH but the urethane still needs N,C,O,O,C,N,R2 but that's just another diisocyanate. So N polyols combine with N+1 diisocyanates to make an N-urethane. That's all the O Chem theory you need to know. Now everything is practical and oriented toward polyurethanes. Go learn about DNA and protein and other chain molecules elsewhere. PRACTICAL POLYURETHANE: Here's what you do: Mix isocyanates MDI or TDI with polyols, catalysts, surfactants, blowing agents, etc., in a high pressure impingement mix or low-pressure mixing chamber, thence into a mold to foam up and solidify. In our case it's probably a two shot mix means there's a Part A and a Part B: Part A has polyisocyanate prepolymer, made of MDI/TDI with some polyol or polyester, to build molecular weight as a linear prepolymer and reduce toxicity. Like glycol (1 to 2 of DI) thus adducting DI into longer chains, more viscous, fewer NCOs available so less reaction needed to finish (thus less time), less water-sensitive, less cross-linkability. Or dipropylene glycol 2:3 of MDI reduces free NCOs to 8.25%. Part B has the rest of the polyol or hydroxyl groups, plus the rest, like catalysts, fillers etc. but also emulsifiers, anti-foaming agents, curing agents. MDI/TDI: "NCO" or isocyanate, you might guess, is irritant and poisonous. Toluene and Benzene are carcinogenic. They'll react with anything, almost like H2O2, hydrogen peroxide. It wants to grab any organic molecule, like your body for example, and react with it, decomposing to methanes or whatever and eating up whatever it grabbed out of your cell wall or mucous or endothelial membranes in your arteries, hampering or killing that bit. Keep them safe in tanks. They also like to go off with any old water and oxygen nearby, so don't let there be any humidity or oxygen in their tanks or they'll be useless. Put Argon (Bloxygen) in or pump a nitrogen blanket into the tank after you pour some of it out, to save it. Like you save your fine wines. "TDI" is Toluene Di-Isocyanate. The R in the middle is a Toluene. TDI can have its NCO's adjacent to the methane(2,6, counting from the methane as position 1) or 1 adjacent, 1 opposite.(2,4 TDI, more reactive) "T-80" has 80% 2,4 (slab foams); "T-65" has 65% 2,4 (some viscoelastic foams); "T-100" has 98% 2,4 (soft foams, prepolymers, freezes at 21C). TDI is CAS 584-84-9, PPE required for skin, eyes, 3M SA ("Supplied Air") air filter. "MDI" is Methylene Di-Isocyanate, which means the R in the middle is two benzenes linked by almost a methane, CH2 not CH3, with NCOs on the outside ends of the benzenes. When synthesized, separate monomeric MDI is for non-foams, and polymeric MDIs is for wood binders, rigid foams, viscoelastic foams. Buy MDI's by viscosity, %NCO by wt., and acidity. MDI is CAS 101-68-8 (Chemistry Abstracts Service ID number). Use PPE for skin, eyes, 3M SA filter. The "ISOCYANATE INDEX" I = #NCO's/OH = 2(N+1)/2N if fully reacted. If N small then I->2. N large then I->1. I==1 means exact "stoichiometry" (mole(cule) counting). Index is commonly manipulated to influence foam physical properties. The PR about polyurethane is that all the toxic bits are reacted away and so they're safe. But that's only if the index is 1, so all the NCO's react with all the OH's, and neither is left to make trouble. If not, then not. If not fully reacted (excess polyols), you get thermoplastic PUs with I<1. Otherwise thermoset. For rigid foams (e.g I==1.5 to I==2) I++ => density--, compression strength--, glass transition temp++. tensile strength++. To match index when switching from TDI to MDI, note that the TDI NCO is 48%, vs MDI NCOs is 30% by weight so you'll have to adjust weight to get the same index. Methylene Di Isocyanate (MDI) less often, and Toluene Diisocyanate (TDI) more often, can be used for flexible foams. In fact TDI is mostly used for flexible PU foams. $0.96-1.25/lb and 15% below list is market price. Use in a hood. Monomer MDI is for solid casts, Polymer MDI for foams and flexible foams. Also MDI for thermoplastic PU's like TPU skinning layers. MDI and TDI are AROMATIC. They discolor under light, very reactive. Whereas ALIPHATIC polyisocyanates are slowly reactive, light-stable (good for paint). Polycaprolactone is aliphatic. Carbo-di-imide modified MDI is used for vehicle arm and head rests, shoe soles. POLYOL: Polyester polyols/diols vs polyether polyols/diols: Polyester diols are more expensive, viscous, hard to handle but make for more toughness (slick, strong), but bad in wet/humid environments (hydrolysis!) unless it's a 2-methyl-1,3-propanediol based polyester diol. A type is the polycaprolactone polyol. They started sooner in 1954 with TDIs. But now only 10% of PUs are polyester based. Typically made by a condensation reaction of ethylene glycol or other diol and dicarboxylic acid. Rigid foams are generally polyester based. Polyether diols: DuPont polyether polyols (1956) were cheaper, easier to handle and more water resistant so became more popular. 90% of PUs are polyol or polyether based. Flexible foams are generally polyether based. Polyethers are made by addition polymerization of polyhydroxyl starter with epoxides propylene oxide (PO) (mainly; gives flexibility but hydrophobic and slow) or ethylene oxide (allows faster reactivity and more CO2 & H2O solubility), or both. Polyether polyol functionality (HO count per molecule) is 2 for rubbery(propylene glycol), ~3 for foams (glycerine), ~6 for rigid foams (sorbitol 6, sucrose 8) (Low means more linear chaining, high means more cross-linking.) Polyether diol PPG2000 is used as a diluent in early foaming because of low viscosity and then as a soft segment component. Polyether diol PPG4110 is another soft segment component. Glycerine is the polyol starter for foams; add PO or EO in your designed order: e.g. cap with EO for HR & Molded foams. EO content evidenced by cloud point; predicts reactivity. PTMEG is a polyether diol. High molecular weight polyols make more flexible PUs, >250MW typical. Slabstock 4000MW glycerin based. Molded & HR: 4-6000MW, triol and >3. X glycerine, 3X*N propylene oxide, higher N => more flexible polymer Low molecular weight polyols: less viscous, makes more rigid PUs, aka starters and cross-linkers. Organic polyols (hypoxidizing soybean oil can make a lot of hydroxyl groups on it; castor oil already has HOs) can be tailored to flexible or rigid or in between. PolyCaprolactone polyols (MDI) can be used for TPUs (but evidently not for foams). PTMEG (Poly Tetra Methylene Ether Glycol) is a common and plasticky PU, great for TPUs. THF -- H* --> PTMEG. This is also known as Terathane from Invicta or PolyTHF from BASF; (You can order 1KG samples from Gantrade.) From 250-3000 molecular weights can be processed into high molecular weights (>40k). POLYURETHANE ADDITIVES: SURFACTANTS modify the foam properties. e.g., silicone glycol copolymer (e.g. mixed with block copolymer with 2000MW segments of polyoxypropylene (80%) and polyoxyethylene(20%) (BASF Pluronic L-101)), (1% Dabco DC-197 a silicone glycol co-polymer emulsifier from Evonik for structural foam). These control cell size, cell opening, mixibility with water &c., stabilization vs collapsing. The type of silicone surfactant depends on if the foam holds up well already (high resilience), as well as formulation, processing, and target specs; each tailored to the type of foam you're making. BLOWING AGENTS make the bubbles during polymerization, and are usually low boiling point liquids volatilized by exothermic reaction heat (which can degrade the product). They are used with integral skin flexible foams (which are also higher density). Initially these were CFCs, HCFCs, HFCs, but water as blowing agent started in 1980s. Water (or with methylene chloride) combines with the isocyanate creating CO2 to make flexible (but fragile) foams. Pentane is more environmentally acceptable than CFCs. As is polypropylene glycol grafted to polyethylimine (PEI) which adducts CO2 (for blowing) leaving an ignoreable bit of amines (per Long An & Xie 2020). Direct air/gas injection also can add foam. Liquid and supercritical CO2 is a new blowing agent, but requires special handling for temp and metering. PEI seems to be the winner as of 2020. 25kPEI-CO2 or PPGx-1:y=zPEI-CO2. Auxiliary Blowing Agents cut the water->CO2 heat, and they vaporize to help foam expand, make it softer. Liquid CO2 most common; Novaflex, Cardio, Beamech also; Acetone and Methylene Chloride less common. Isopentane, HCFCs. Add silicone oils to stabilize and regulate structure, calcium carbonate (filler) for early strength (but mattresses with CaCO3 lose resiliency). Reduces blistering. 0.5%-30%. CATALYSTS: tin-butyl-tin dilaurate and tin octylates (stannous octates) for microcellularity, and RIM, and ultrapure amines (DABCO, tertiary amines, triethylenediamine), usually both for a fast reaction (i.e. for a foam). Amines favor water+XDI reaction over polyol+XDI reactions (blow catalysts). Some amines promote cross-linking (rigidity) and others control cell structure. Triethanolamine is a catalyst and cross-linker; glycerol is a cross-linker. The early catalyst for 60 years was KOH but slow, unsafe, and required refining it out afterwards. For last 25 years organo-metallics like tin or double-metal cyanide aka DMC or IMPACT, favor polyol-OH reaction, allow continuous use, much faster, much less process waste, VOCs, and wasteful side reactions so better, 2%. Catalysts influence foam stability/tightness, flow in the mold, skin formation, cure/demold time. Combine gel catalyst (tins, TEDA(A33)) and blow catalyst (BDMAEE (A1)) for balanced effects (DMEA). Then a little phenolic or hindered amine anti-oxidant to protect the polyol OH's, more for slab foams to protect against foam oxidation, foam scorch, or fire. Oxygen exposure of stored polyols (uninhibited polyethers) leads to peroxides, yellowed, stinky, and uncatalysable. CHAIN EXTENDERS are reactive di-functional glycols, diamines, hydroxyl amines which react with the isocyanate to change the hard/soft segment relationship. PIGMENTS are colored pastes added to the polyol side, organic or inorganic. FILLERS can include calcium carbonate to lower total cost, and glass fibers (for RIM). But see Dr. Koop's article saying consumers are being screwed by fillers in unregulated markets, which break down foams quickly. ANTI-FLAMMABILITY AGENTS: melamine, hydrated alumina (aluminum trihydrate), or additives based on chlorine, bromine, (or iodine or fluorine), or phosphorus chemistry. "[C]onventional flexible PU foam [is] formed from a reaction mixture of diisocyanate, glycol (glycerine?), water (max 4.3%, can get 4.7% with filler), foam polymerization catalyst and gas generating catalyst." (European Patent EP0354511A1) WATER destroys your NCOs (isocyanates), immediately grabbing 2-3% on exposure, degrading the DI, causing early gelling, CO2 foaming, reducing shelf-life. Keep the water <0.005% by weight out of your DI's. Mix with paddles, <3 minutes, no shaking, don't aerate-mix unless for foam. Nitrogen blanket or desiccant to store. CO2 is being used as a blowing agent replacing CFCs and methylene chloride. Liquid CO2 needs to be kept in solution in CO2/polyol and CO2/mixture, which depends on tight temperature control; water and surfactant reduces CO2 solubility; ethylene oxide increases CO2 solubility, TDI may also reduce CO2 solubility, so pressurize while adding TDI. CO2 might cool the exotherm by 1C per %CO2/polyol. CO2 seems to need air bubbles as nucleation sites to build on. More CO2 more reduces viscosity and surface tension, therefore the tinier bubbles. And once foamed, the CO2 is out of solution, therefore viscosity rises, therefore the foam doesn't fall while finishing the polymerization reaction. Silicone stabilizes LCO2 FPF; Silicone L-3102 is a foam stabilizer. Linde-gas.com. Meter the liquid CO2 into the mixture carefully; feed pump removes bubbles before metering for accuracy. CO2 within the polyol itself (as opposed to during the polyol+diisocyanate reaction) makes polyethercarbonate as the polyol which can improve load-bearing of the foam, up to 14%, but also makes it much more viscous. Aim high enough so there is enough NCO to react (so close to I==1) but aim tight, I<1.05 so little excess NCOs/DIs, which will react with atmospheric water later. When MICROBES attack PU it's the polyol part they attack, for biodegradability use amorphous soft block components (polycaprolactone based means <50-60% hard crystallinity.) KPRC: polyols from vegetable oils are now available. Patent 4374209: "... for the preparation of flexible foams the polyether polyols preferably have hydroxyl numbers in the range 20 to 80 and from 2 to 4 hydroxyl groups per molecule for example ICI Polyol PBA 1233. If desired mixtures of polyether polyols can be used." ICI is now SPI Polyols Inc., and PBA means polybutyline adipate or perhaps specifically poly-1,4,butylene glycol adipate diol. "Polymer Polyols": Some formulations have polymer chunks suspended in the (polyether) polyol medium and those incorporate into the foam cell walls. E.g. Styrene AcryloNitrile aka SAN adds up to 50% solids to the formulation. PHD (w/hydrazine) and PIPA (with PU chunks) types also exist. Can add reinforcement, make more open cells. Or can plug filters. FORMULATION RANGES: Parts by Weight 100 Polyols, Polymer Polyols 1-10 Water, physical blowing agents (e.g., liquid CO2) 0.2-5 Surfactants 0-2 Catalysts 0-5 Cross-linkers, extenders 0-150 Fillers 0-10 Etc: colorants, cell-openers anti-microbials, anti-stats, FRs, fillers 20-70 Diisocyanate TDI, MDI, pMDI POLYURETHANE DESCRIPTIVE PARAMETERS: Read ASTM 3574 Density (1.5-40lb/cu.ft.) or 0.5-8pcf. ( == quality) Firmness: (25%IFD 5-150 lbs/50 sq in): super-soft, [*]soft, medium, [*]firm, high-load, semi-rigid. Grade = XXYY where X.X is density per cu ft., and YY is IFD25 (lbs to compress 50sq in by 25% on 4" thick) So a four-layer cushion design might be cloth cover, light fill/fiber 1", comfort foam 3015, structure foam 3040 Tensile Strength Flexible foams: (18psi polyester; 25psi polyether based) FF Tear strength can exceed natural rubber. Rigid Foams: 800psi! but brittle/friable. Surface Feel: measured as IDF25, indentation force, lbs to indent 25% of 4" piece for a standard board, in the range 7-45lbs (45: thin cushions for commercial bar stools) (17-35 for seating) Durability: [*]heavy-duty, normal-duty, light-duty Support: normal support, high support, high resilience (for greater user weight range) a.k.a. Compression Modulus = Modulus = IDF65/IDF25 large where soft but supportive. Larger with greater density. Comfort Also PU resists rot, many solvents, vermin; great for heat and sound insulation; great properties for EM filtering and transmission. Flexible Polyurethane Foams are 0.9-6 lbs/cu ft. furniture applications: 0.9-2.5 lbs/cu ft. Costs a little more for a lot more durability. USES: 50% of all polyurethane is flexible; 60% of that or 30% of all is cushioning and padding like furniture, 1/4 of that is automotive upholstery. Definitely use spray PU in new construction under drywall. Naugahyde: integral skin PU made to look like leather. Ski boats: RIM under pressure: smooth surfaced but light, rigid. CASE coatings adhesives (no solvents, no VOCs created) PU is used as surface wrap made of softer foam. MANUFACTURE: RIM: Reaction Injection Molding (Injection Molded but foaming reaction takes place) Ashida Kineyoshi, Polyurethane and related Foams: chemistry and technology CRC Press pp79-81 Produces high-density skin with low-density core. For Polyurethane RIM Ingredient A: polyisocyanate Ingredient B: polyol, surfactant, catalyst, blowing agent. Auxiliary blowing agents. Mixing equipment: Yongjia in China sells low pressure ($14k)and high pressure ($50k) mixing meterers. AircraftSpruce.com has a two-component metering shot machine that can potentially serve for small quantities if the ratios are in their scope, except maybe they won't keep water out of the resins. SUPPLIER LIST: Main PU and catalyst suppliers: Huntsman, BASF, Covestro, Evonik, Kao Corp., Lanxess, Air Products, Wanhua Chemical, Zhejiang Wansheng, Dajiang Chemical, Momentive, Tosoh Foam Supplies, Inc. sells SLUG mixing head systems with formulated supplies. Ecoflex integral-skin formulations. Ecomate H-CO2-Methane blowing agent. Generally Recognized as Safe. Industrial Polymers 800-766-3832 no longer sells what's shown on their YouTube videos as self-skinning and good for seat cushions. Now they sell: FX Foam 600 (6lbs/cf) 288cu in/1 lb mixed resin FX Foam 800 (8lbs/cf) 216cu in/1 lb mixed resin $76.64/2gal kit, 3.8% discount for 5x and 50x volumes Amcor Inc, Thomson GA 30824. blowing and foaming agents (isopentane) 800-262-6685 just call and ask. Comcast Urethane. Self-skinning pentane-blown PU-RIM and PU-foams, babypoint changing pads. Marshall MI 49068. Shell: RIM resin supplier. Dow Chemical: RIM resin supplier US Composites Shopmaninc.com various densities pourable 2-part urethane foams. Polytek development corp., Polytek.com has self-skinning, colorable, polyurethane foams, maybe (PolyFoams). 800-858-5990, Easton PA. Emailed a tech support ticket 12/11/2020. Rojac.com (UK) Gantrade: polymer and urethane resin supplier worldwide. In totes, drums, pressure-cylinders, rail cars. Sika: Good for blue-clear epoxy for river tables, etc. website does not emphasize foam at all. Smooth-On: FlexFoam-iT IV Flexible Urethane Foam Foam-iT 4 Rigid Urethane Foam UreCoat Flexible Urethane Coating Ignite pigments StratasysDirect.com various polyurethane foam resins. e.g. FoamFlex V412 ReynoldsAm.com Smooth-On products. 10422 SE 244th St., Kent WA 98030 844-512-8208 Vencorex.com (Freeport TX) recommends TDI aromatic isocyanates for vehicle seating Scuranate T80. 2,4 mixed 80-20 with 2,6 Toluene Diisocyanate Scuranate T65. 2,4 mixed with 2,6 Toluene Diisocyanate better for high-resilience high load-bearing flexible foams. PAR-Group.co.UK manufactures products with skinned flexible PU foams. acoustafoam.com UK manufactures products with skinned flexible PU foams. Alchemie.com UK manufactures PU self-skinning foam resins PU3580, PU3583, PU3587, PU3588. NorthStarPolymers.com MDI based water-blown polyether for a flexible foam. also gels to cast inside soft parts like bicycle seats. also base chemicals for your formulation in quantities you can't get from Dow. also they will do short cycle custom formulation work to figure out whats needed. Minneapolis MN. Northstar's MSA-018 is a polyester MDI useable for flexible foams. UniqueFab.com engineering support; RIM for office furniture and sporting goods. General Plastics (Tacoma!) has self-skinning intumescent PU foams but will not sell resin only finished products. Boeing certified. Does custom formulations. Ciba-Geigy Corp East Lansing MI 800-875-1363 urethanes Ciba Geigy: 1990s RIM supplier. Ciba Furane Products, Los Angeles CA 818-247-6210 urethanes Ashland Chemicals, Columbus OH 614-790-3639 urethanes Lord Corp Erie PA 814-868-3611 urethanes Morton International Chicago IL 312-807-3218 urethanes Fisher Scientific Pittsburgh PA 412-963-3300 DMF (dimethyl formamide solvent) to bond TPU to TPU. Bostik Inc Middleton MA 508-777-0100 Urethane solvent/adhesive B-7133, to bond TPU to TPU. C.U.E. 724-772-5225, Cranberry Twp PA, since 1957 polyurethane molder. Dual-durometer parts a specialty; all PU chemistries are available; Engineering support to get to market. Kelong Chemical Reagent Plant, Chengdu Sichuan China) sells cross-linkers triethanolamine and glycerol. Chengdu Advanced Polymer Technology Co sells various raw materials including polyether diol PPG2000 and PPG4110. Voronol 490 is a polyol used in structural foam. (from Dow Plastics) Dabco 125 by Evonik is organotin gelation for HR (High Resilience, like memory foam) for foam breathability and increased load-bearing properties. Dabco T-96 stannous catalyst for polyether flexible foams. Specialchem.com lists selections for additives, 185 Dapco's etc. Baovi: Shandong Baovi Energy Technology Co., Ltd., supplies TDI &c including free samples and 1kg min quantities, ships in 1-5 days, on alibaba.com KBFoam.com, San Diego/Tijuana subsidiary of a Korean mold company does molds and styrofoam. CustomFoam.com Ontario Canada foamer offers Cadillac design/dev/process/prototype/production OEM services. XX Mantecservicesinc.com Seattle custom molded PU contract manfuacturer XX (near Ballard marina). 206-285-5656. Request quote after NDA. Molders: https://www.thomasnet.com/products/polyurethane-foam-molding-62220264-1.html Consultants: XX LinkedIn Tony Arnold, fuzzybrands.com, Greater Derby area (UK) SAFETY: Used for decades in major industries BUT: Avoid overexposure causing irration and sensitization. Vapor pressure is 720x less than water. Odor is not a good indication of exposure. Max limits are 1ppb for 8Hr days, 5ppb for 15min, 20ppb hard max. Have local exhaust ventilation. Wash Hands and Clothes. Use PPE: nitrile/butyl rubber gloves, check OSHA for respirator, eye/face shield for splashing. Read the MSDS, supplier resources, and trade association guidance. ------------------------------------------------------------------ Molding Procedures ------------------------------------------------------------------ Wax mold interior with Johnson Paste Wax 5x, then grease with Vaseline, according to Custom Tool and Pattern of Enumclaw. Day Prep: Shop for supporting materials and tools: SpeedGlas AdFlo welding hood, get OV filter option. Get a gallon of acetone so there's plenty for cleaning. Test the digital scale: tops out at 1300g. Get new Organic Vapor cartridges, 3M60923 or current (cheap insurance) Nitrile gloves, face shield. Honeywell 17000 activated carbon filter. ------------------------------------------------------------------ Molding Procedures Hang These Instructions Atop Workspace ------------------------------------------------------------------ Prep For Action: Organic Vapor mask, gloves, face-shield, body suit, carbon filter room Plastic protection around floor and room. Rags, paper towels, bagged bucket for post-op mess. Clean/Scrape out the previous buckets if possible. Pour 3" acetone into a spin jar. Open the door for operational ventilation. Foam QC: mix a test amount, pour it in a bag. Test proportions, maybe also flow rates, of each, if you auto-measure Test reactivity by when it sticks to a wire, and when it gets tack-free to the touch Mold: Plan Vent orientation. Open vents. Plug unused vents with hard wax. Re Wax, Dry, Buff the mold. Re Vaseline the mold. A Pour: Open A Measure A into container A. Scale G, Tare 0, fill to A-Mass grams. Blanket & Close A B Pour: Open B Measure B into container B1 and also into B2 if > 1.3kg overlimit on scale, then 500g in B1 and B-Mass - 500g in B2. Blanket & Close B. Pour B from container B2 into B1, scrape B2, add acetone to empty B2. B PreMix: Mix B1 with paddle. Mix A & B: Pour A into B1; scrape <4seconds from A but it's a mess: stop soon. Mix B1 with A & B with paddle forX12X 15-30secs. May start foaming. Fill Mold: Pour B1 into mold, scrape B1, close mold with lock and screws, undo hinges and screw the other side Cleanup: Spin paddle in spin jar until clean, set aside. Dump some acetone from spin jar into B1 and into A Hand-mix acetone, scrape/dump/rag-wipe B1 first then B2, A Check the time. Come back in X30XminutesX 2 hours to open the mold. ----------------------------------------------------------------- FAILURE ANALYSIS: Case 1: Partially Collapsed; Partially Filled. 1A: After 30 minutes the top half collapsed into the bottom by about 3/4", maybe 25%. 1: Inadequate mixing causes collapse. Ok, mechanical paddle mixing for 12 seconds wasn't apparently enough. Try 30sec as sometimes recommended and do plenty on bottom and sides. 1B: No Vent. I drilled for backpressure release only after 4 minutes, whoosh meant Overpressure, explains parting line extrusion, and underfilling of the mold. Rejected possible causes: Insufficient material? Lost some to B2. Double-pour 1/2 more. Insufficient curing time: waited 35 minutes, now leave it 2 hrs. N/A: Too much height? No, it rises out of a mixing jar all the time. that doesn't mean it can lift the previous part into the top of the mold like if you fill it upsidedown into the top, put the half-part on, then close the bottom over it, will it push the half-part up into the bottom and fill the rest of the top half, probably not because of the weight of the half-part. Just because it can lift its own weight doesn't mean it can lift the weight of others. So double-pour will be on top of foam and have to be spread out and thick enough to fill to cover the top. N/A: silicone mold release: don't use it. N/A: cold temperatures. But it was 78 to 74 degrees and 1 day with the material in that environment.