In the future, we will try to discuss as little isocyanates as possible. After all, they are beyond the control of our grassroots. Most of the talk is about the combined dosage of polyether (ester) polyols, catalytic system, water/physical foaming agent, and process coordination. Anyway, idleness is idle. After a hundred years, most of the bones will not be left, but words and word of mouth can leave traces. There is no need for romance, the book has its own beauty like jade, and its own foaming skills.
[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 4110 series, the broadest spectrum, has an astonishing difference. 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. Its products have relatively fine cells, good dimensional stability, and large 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 praised 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.
[Rigid Foam Polyether] The best sucrose-type polyether I have ever seen is +glycerin, with a viscosity of 3000~4000. At that time, the factory had just opened, and the people who produced it were chemical workers, and they were “blind” regardless of cost. “Do it”, I have received many requests from POs. I have used it to make imitation wood, disinfection cabinets, freezers, and yacht fillings, 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.
[Rigid foam polyether] Sucrose-type polyethers represented by 4110 are all started from 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 (mole) ratio, a high viscosity, and a hydroxyl value lower than 400. It is generally coded 380 or 360. Regardless of its high viscosity, it has low fluidity in the mid-foaming stage. But it is excellent and 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 composite materials. Dual functionality 204, 210, and 220 are also common choices for improving imitation wood systems.
[Hard foam polyether] 403 is the most common hard foam composite material】⑤ Ordinary filling 1.5~2.0; ⑥ Intermittent cold storage plate 1.5~2.0; ⑦ Continuous plate 1.5~2.5; ⑧ Color steel tile insulation layer 2.5~5.0; It should be noted that if the product needs to pay attention to the apparent hardness and low ambient temperature To prevent the powder from becoming brittle, use as little moisture as possible. The amount of water must be combined with the amount of physical foaming agent, the composition of the catalyst, and the temperature control of the foaming process to control the density of the final product.
[Hard Foam Silicone Oil] Hard foam silicone oil performs the following functions: 1. Mix polyols, water, catalysts, physical foaming agents, flame retardants and other components together securely, so that the combined materials are not extremely Quick to layer. 2. It can make the combination material and isocyanate evenly dispersed/fused together. 3. When the combined material and black material (isocyanate) begin to react, it can provide a nucleation center point; 4. When the nucleated air bag grows, it can stabilize the air bag wall without bursting and bursting.
[Hard foam silicone oil] 6. Some types of silicone oil can cause some holes in hard foam products to achieve dimensional stability of the product. Because silicone oil is highly targeted, such as: more water/less water system, different polyether main components, differences in physical foaming agents, differences in 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 refer to 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 Small Test】For all hard foam products, starting with a small test is the most economical and quickest 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 discovery 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.
