Sponge is a porous material with good water absorption and can be used to clean items. Commonly used sponges are made from wood cellulose fibers or foamed plastic polymers. In addition, there are also natural sponges made from sponge animals, and most natural sponges are used for body cleaning or painting. In addition, there are three types of synthetic sponges made of other materials, namely low-density polyether (non-absorbent sponge), polyvinyl alcohol (highly absorbent material, no obvious pores) and polyester.
When the polyurethane sponge is foamed in large pieces, sometimes the surface will crack, and the length will appear indefinitely, sometimes on the side and sometimes in the middle. What is the reason? Here are some points for your reference. Welcome to come Smash bricks!
1. Increase the amount of tin catalyst and reduce the amount of amine. If the amount is appropriate, it is not a problem with the silicone oil.
2. Increase the temperature of the drying tunnel and conveyor belt in the initial foaming area.
3. Check whether the speed of the side paper and the conveyor belt are synchronized, and whether the heights of both sides of the inclined plate are on the same horizontal line; whether the assembly line transmission and the side transmission are uniform and synchronized. It is necessary to pay attention to the close coordination between the foaming speed and the transmission speed.
4. Control the edge lifting machine well and lower the edge lifting film.
5. The above inspection points also need to be combined with factors such as material temperature, equipment, water metering pump, external force and surrounding environment.
Silicone oil has excellent heat resistance, electrical insulation, weather resistance, hydrophobicity, physiological inertness and small surface tension. In addition, it also has a low viscosity-temperature coefficient and high compression resistance.) Some varieties also have Has radiation resistance.
Silicone oil has many special properties, such as anti-oxidation, high flash point, low volatility, non-corrosive to metals, non-toxic, etc.
Basic classification
According to the chemical structure, it is divided into methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trisilicon oil Fluoropropyl silicone oil, methyl vinyl silicone oil, methyl hydroxy silicone oil, ethyl hydrogen silicone oil, hydroxyl hydrogen silicone oil, cyanide silicone oil, etc.;
According to application, there are damping silicone oil, diffusion pump silicone oil, hydraulic oil, insulating oil, heat transfer oil, brake oil, etc.
Main purposes
Commonly used as high-grade lubricating oil, anti-vibration oil, insulating oil, defoaming agent, release agent, polishing agent and vacuum diffusion pump oil, etc. Among various silicone oils, methyl silicone oil is the most widely used and the most important variety of silicone oil, followed by methylphenyl silicone oil. In addition, there are ethyl silicone oil, methylphenyl silicone oil, nitrile silicone oil, etc. Various functional silicone oils and modified silicone oils are mainly used for special purposes.
Advantages and Disadvantages
Advantages (1) Excellent shear stability, has the function of absorbing vibration and preventing vibration transmission, and can be used as a vibration damping fluid. (2) Excellent thermal oxidation stability, such as thermal decomposition temperature >300℃, small evaporation loss (150℃, 30 days, evaporation loss is only 2%), oxidation test (200℃, 72h), viscosity and acid value changes Small. (3) Excellent electrical insulation, volume resistance, etc. do not change within the range of normal temperature to 130°C (but the oil cannot contain water). (4) It is a non-toxic oil with low foaming and strong anti-foaming properties. It can be used as a defoaming agent. (5) The viscosity-temperature performance is the best among liquid lubricants, and the viscosity changes little over a wide temperature range. Its freezing point is generally less than -50°C, and some are as high as -70°C. The appearance and viscosity of the oil will not change after long-term storage at low temperatures. It is a base oil that can take into account high temperature, low temperature, and wide temperature ranges.
Disadvantages
(1) Small surface tension (easy to leak from the machine).
(2) The gas solubility is large (it is difficult to design a gas sealing device).
(3) Silicone oil has a large thermal expansion coefficient (which may cause overpressure problems).
(4) Silicone oil has poor lubricity, especially for steel-steel friction pairs.
(5) Certain hygroscopicity (after the water content is higher than 100×10-6, the electrical performance drops sharply)
Application fields
Silicone oil has a wide range of applications. It is not only used as a special material in aviation, cutting-edge technology, and military technology sectors, but also in various sectors of the national economy. Its application scope has expanded to: construction, electronics and electrical, textiles, automobiles, Machinery, leather and paper making, chemical and light industry, metal and paint, medicine and medical care, etc.
The main applications of silicone oil and its derivatives are: release agents, shock absorbing oils, dielectric oils, hydraulic oils, heat transfer oils, diffusion pump oils, defoaming agents, lubricants, hydrophobic agents, paint additives, polishing Agents, cosmetics and daily necessities additives, surfactants, particle and fiber treatment agents, silicone grease, flocculants.
