A brief talk

[Hard foam polyether polyol] Functionality f. I originally thought that f ≥ 3 would be the authentic hard foam, but this is not the case. It is completely possible to use polyester polyols with f=2 or polyether polyols containing primary hydroxyl groups as “white materials”. It should be noted that the trimerization catalyst must be used as the main catalytic system, water should be used sparingly (quantitatively), and physical foaming agents (141B, cyclopentane, etc.) should be used as the main means of adjusting density.
[Rigid Foam Polyether] The quality of our polyether is not determined by quality or use, but by price. The prices of the same series of products sometimes vary by more than a thousand. The broad spectrum 4110 series is even more amazing. In the final analysis, it comes from the desire of mainland compatriots for quick success and instant benefits. Personally, I feel that polyethers starting with glycerol are obviously better in terms of detectable indicators of the final hard foam product, storage resistance of the composite material, and the applicable tolerance of the foaming process.
[Hard foam polyether] A series of polyethers started from sorbitol. The cells of its products are relatively fine, the dimensional stability is good, and there is a lot of room for catalytic adjustment in foaming production. Even in this era of “low price is king”, sorbitol-based polyethers will still not fade out of the market. Some imitation wood products also require this type of polyether to be ready. For example: high-end mirror tables and coffee tables with realistic textures, gilded picture frames, and intricately structured patterns.
[Rigid foam polyether] “Sucrose-type” polyether is highly regarded for its high rigidity and affordable price. The initial characteristics of 1050 are high hydroxyl value, high functionality, good hardness, and good dimensional stability of products. Due to its high viscosity, the foamed composite material has poor foaming fluidity, poor miscibility with other compatible polyethers, and the products are brittle and The pore size is coarse and theoretically requires more isocyanate consumption, so it is gradually replaced by other improved mixed starting sucrose polyethers.
[Hard foam polyether] The most useful sucrose-type polyether I have seen is +glycerin, with a viscosity of 3000~4000. The factory had just opened at that time, and the people in charge of the production were chemical workers, who “fooled around” regardless of the cost, PO It has been connected a lot. I have used it to make imitation wood, disinfection cabinets, freezers, and fill yachts, and there have been no complaints. It has fine cells, low viscosity, no powdering in cold weather, and excellent resistance to high and low temperatures. The good times did not last long, and the factory could not continue to operate.
[Hard foam polyether] Sucrose-type polyethers represented by 4110 are all started with sucrose + glycol. Most of them choose diethylene glycol due to cost issues. The viscosity of such polyethers can be smaller. However, some 4110 varieties will be added with cheaper PET alcoholylate or simply palm oil, etc. This type of polyether is used for general filling, non-low temperature insulation, and low product deformation requirements. Because its “activity” will be significantly high, it will be difficult to adjust its foaming fluidity with a catalyst.
[Hard foam polyether] There is also a type of polyether with a high sucrose (molar) ratio, high viscosity, and a hydroxyl value lower than 400. It is generally coded 380 or 360. Although it has high viscosity, it has excellent fluidity in the middle stage of foaming. , suitable for the insulation layer of refrigerators and freezers. The compatibility with cyclopentane is relatively good. It is generally necessary to add a small amount of binary and terpolyether (ester) with smaller viscosity to make composite materials. There are also sucrose polyethers with a hydroxyl value lower than 300, but domestic manufacturers cannot make them
[Hard foam polyether] Polyethers with low hydroxyl value (4.0), and low viscosity (<5000) are suitable for imitation wood products. If the product requires thick skin, hard skin, and overall toughness, this type of polyether should be the first choice. Small molecule polyethers 303, 305, etc. started from glycerin are also the preferred auxiliary raw materials for improving performance in imitation wood composites. Dual functionality 204, 210, and 220 are also common choices for improving imitation wood systems.

[Hard foam polyether] 403 is a commonly used “soy sauce” for hard foam composite materials. Starting from ethylenediamine, it can significantly improve the cell density of the foam and the overall hardness and shrinkage resistance of the product. The only drawback is that the viscosity is too high and the combination The mixing of ingredients is a bit cumbersome. The polyether starting from urea is more rigid, and the cells must be thicker, making the product more brittle. However, if it is used to produce “flower mud” for flower arrangements, it has unique advantages: the resistance to flower arrangements is extremely small and almost unobstructed.Due to differences in physical foaming agents, catalyst flame retardants and other additives, the selected silicone oil model will be different. For example, for cyclopentane-type composite materials, the solubility of cyclopentane will be greatly improved by selecting appropriate silicone oil.
[Hard Foam Catalyst] 1. We call the catalytic function mainly reflected in the “reaction of -NCO and water” as “pre-catalyst”, such as A-1, PC-5, DMEA. And the greater the amount of water, the faster it rises. There is an interesting phenomenon: using any of the above alone is far less effective than the above three when used together. 2. Those with equivalent catalytic capabilities between “-NCO/water” and “-NCO/-OH” can be considered “balanced catalysts”, such as cyclohexylamine and dimethylbenzylamine
[Hard Foam Catalyst] 3. The main function is to catalyze “-NCO/-OH” and promote the self-trimerization of “-NCO” into rings. We call it “late catalyst”. Those that can cause “surface curing of molded products to be completed as quickly as possible” are also called “post-curing catalysts”. A-33, delayed A-33, organotin, potassium organic acid, DMP-30, etc. Generally, we will use two or more different types of catalysts in combination to achieve a perfect process
【Hard foam test】For all hard foam products, starting with a small test is an economical and quick procedure. We generally regard all polyol components as 100, and the specific composition is left to you; then the proportions of silicone oil, water, and catalyst are based on 100 parts as a reference. For physical foaming agents, the above combination is used as the base and multiplied by the preset percentage. If there is a flame retardant, add it according to the total including physical foaming agent.
[Hard foam test] For example, polyether 4110-95 parts, polyether 403-5 parts, silicone oil-2.0 parts, water-1.2 parts, cyclohexylamine-0.8 parts, A-33-0.5 parts, physical foaming agent 141B —(100+2+1.2+0.8+0.5)×24%=25 parts, flame retardant DMMP—(100+4.5+25)×6%=7.77 parts. The above is a slightly complete formula. In actual application, the ratio of black and white materials should also be taken into consideration. In the above situation, black: white = 1:1.