Generally, we recommend that the dosage of silicone oil is 1.5~3.0% of the total amount of polyether + polyester. Appropriate adjustments must be made according to different seasons and different uses. If you use real 100% silicone oil and add 0.5 parts, the foam will not collapse, but the combination is generally not used immediately after being prepared. Especially in hot weather in summer, some side reactions will always occur during storage, which will reduce the quality of the combined materials. The higher the temperature, the faster the reaction speed. Therefore, it is generally recommended that silicone oil should be added to 2% of polyether + polyester. When the proportion of silicone oil exceeds 5% of polyether + polyester, we think it is meaningless (unless the effective content of the silicone oil you use is only 30 to 50%). The amount of silicone oil is too large, and there is not much improvement in the performance of the composite material. Although there are slight changes in the cells, it will affect other properties such as adhesion. For really good silicone oil, you don’t need to add too much! Someone has done an experiment on the amount of silicone oil in the composite material on the fineness of the cells.
The effect of silicone oil dosage on cell structure
The dosage of silicone oil is adjusted according to actual conditions. Different regions, different climates, different seasons, and different uses have different empirical data. For example, in winter, the temperature is low, the foaming speed is slow, and the cells are easy to become thicker. We recommend that you add more silicone oil, and you can add less silicone oil when it is hotter in summer. When making flame-retardant foam, since flame retardants can easily cause foam breakage, you should also add more silicone oil. For low-density foam, add more silicone oil, for high-density foam, add less; for large foam, add more silicone oil, for small pieces, add less; for refrigerator materials, use a larger amount of silicone oil, and for insulation pipes, add less; for cold storage sprays, the content of silicone oil should be higher. , if the roof is sprayed a little less; if you use good quality polyether (such as Takahashi), polyester silicone oil and add less silicone oil, it will not be a big problem. If you use polyether and polyester that are 20% cheaper than the market price, you can also use For F-11 in the underground factory, even if you add more silicone oil, there is no guarantee that there will be no problems, let alone add less silicone oil. We generally believe that silicone oil should not exceed 5% of polyether (plus polyester) at most and not less than 1%. Different foaming engineers have their own set of experience data, which needs to be summarized and summarized during work.
Problems that may occur when using silicone oil
Turn turbidity: When the weather is particularly cold or hot, some silicone oil will become turbid. This is not necessarily a problem with the quality of the silicone oil. You can ask the manufacturer why. Generally, it will not occur within the specific temperature range of the silicone oil. become muddy. At room temperature, if the silicone oil becomes clear and does not separate after shaking, it means that the silicone oil is fine. If it cannot become transparent, it is likely that the silicone oil has deteriorated;
Silicon oil failure: The current structure of silicone oil is relatively stable and generally will not fail during the shelf life. If it fails, it is not necessarily because there is something wrong with the silicone oil itself. There may be something wrong with the external environment, which destroys the silicone oil and makes the silicone oil invalid. Common problems include the following:
① The cyclopropyl value in polyether and polyester is high. The last process of polyether and polyester requires the removal of cyclopropylene. If the cyclopropylene is not removed completely, the cyclopropylene will break the chain of the silicone oil, thereby rendering the silicone oil ineffective.
② F11 and 141b are too acidic. Since F11 and 141b are highly acidic and contain small molecules, they may destroy the silicone oil.
③ Engine oil. If your equipment leaks oil and the oil enters the composite system, it will also destroy the silicone oil, causing large holes and even collapse.
④ Polyester, organic tin. Polyester that uses organotin as a catalyst or organotin as a foaming catalyst can also cause silicone oil to fail, resulting in large pores and even foam collapse
Layered and stinky. Silicone oil that has been stored in an improper environment for a long time or is contaminated by other impurities will decompose, stratify and become smelly. Such silicone oil has a foam-breaking effect and cannot be used.
Storage, transportation and use of silicone oil
Silicon oil is best stored in a dry, cool environment;
If stored for a long time, it is best to roll it on the ground for a minute or two before use;
After opening the barrel, if it cannot be used all at once, be sure to tighten the lid after taking the material;
Silicon oil is a non-toxic, non-corrosive silicone surfactant and is not a dangerous product. Most varieties of silicone oil are easily soluble in water, but some special varieties may not be easily soluble in water and will be soluble in alcohol; if it sticks to the skin, don’t be too nervous, just wash it with water. If it splashes in your eyes, rinse it with water and see a doctor; silicone oil It cannot be used as food to satisfy hunger. If you eat it by mistake, you still need to wash your stomach;
It’s too wintery��, some varieties of silicone oil will be turbid or even agglomerated. It is best to heat them to room temperature and roll them evenly before use;
Shelf life of silicone oil: reasonably stored for no less than one year. Silicone oil that has been stored for a long time can be used if its physical properties are normal and it passes the inspection. Silicone oil produced by our company for more than five years has been inspected and will not affect its use.
Be sure to use clean special utensils when taking a small amount of silicone oil. Strong acid, strong alkali or organic tin will have a destructive effect on silicone oil. If you mix utensils with such substances, it is likely to cause the entire barrel of silicone oil to deteriorate
Current status of silicone oil market
Although there are no more than ten manufacturers producing silicone oil, the current market is also quite chaotic. There is no uniform standard for quality. There are at least some basic standards and testing methods for raw materials such as polyether and foaming agents, but for silicone oil, each manufacturer only has its own standards. Without unified standards, quality will vary and prices will fluctuate greatly. The cheaper ones may be about the same price as polyether 4110, while the more expensive ones may cost 70 to 80 yuan per kilogram.
I can tell you here that the price of hard foam silicone oil is more reasonable at 25 to 50 yuan/kg, because the cost is there, believe it or not, it is there! Real silicone oil is used as an additive How is it possible that the price is similar to that of 4110? The most basic silicone raw materials are more than 30 yuan, plus transportation, processing, and making silicone oil, you still have to make some money! Has the price of catalyst been higher than 4110? Some people The silicone oil we use is very cheap. I advise everyone to think carefully about why silicone oil is so cheap. Why?
We all work in factories. What do you think when your customer says that the combination of ingredients I use from another company is 2,000 yuan cheaper than the one from your company? You will definitely wonder whether the ingredients in this combination are all glycerin or not. Castor oil or… Adding polyester is not cheap!!! Some people say that I use other people’s cheap stuff, but it’s no problem anyway. But I still hope that when you use cheap silicone oil, add 0.5 parts of silicone oil and bake it at 60°C for 5 days. After foaming, compare the changes in the cells with the more expensive silicone oil, and then determine whether there is any difference between the two silicone oils. Under normal circumstances, adding 2 parts of silicone oil may not cause any problem, but we must prevent unexpected situations. For better silicone oil, the dosage can be reduced, but the benefits will be the same for the compound material factory. Some people say, I dare not add less, for fear of causing problems, so if you add more cheap silicone oil, you must have added more silicone oil, not necessarily!! You dare not add less, but you dare to add cheap silicone oil!!
Cheap dishes are most likely fried in gutter oil; cheap rice is likely to be added with plastic particles; cheap noodles may be added with talcum powder. I don’t know if you believe it or not, but I do!!
To sum up the above:
1. Silicone oil is a key additive in the composite material or in the foaming process. It is not used much but has a great effect. Without silicone oil, the foam will collapse, and if the silicone oil fails, the foam will collapse.
2. The quality and price of silicone oil are related. You get what you pay for. If you want to buy meat for the price of tofu, the possibility is very small. If you are smart, others are not stupid.
3. The functions of silicone oil: emulsification, nucleation, foam stabilization, and flow.
4. When purchasing silicone oil, you must indicate your purpose when purchasing silicone oil. Silicone oil manufacturers can help you choose the right product based on your requirements and the characteristics of their company’s products.
5. Inspection of silicone oil: It is best to use the reduction method for application experiments when testing silicone oil, which is more representative. The apparent physical property indicators cannot represent the actual effect of silicone oil.
6. The dosage of silicone oil: 1.5-3.5% of polyether + polyester. Our company’s silicone oil generally recommends a dosage of 1.5-2.5%;
7. If there is a problem with the combination material, do not rush to conclusions, and do not say that there must be a problem with the silicone oil. To analyze carefully, I suggest every engineer develop good habits and use clean utensils to seal samples every time raw materials come in. In this way, even if a problem occurs, you can take out the sealed samples and analyze them one by one. Otherwise, if you find the problem but cannot find the root cause, it is not a hurry! Before shipping, you should also keep samples of your products to observe the stability. When customers have complaints, the reasons can also be analyzed.
