Experts count the knowledge in the color of grease!
November 25, 2021
The current technological society has a variety of standard tests and advanced technologies that can be used to analyze grease. However, people are still accustomed to using the senses to identify the quality of grease, they look at the color, touch, smell, and even taste. Some greases have not yet been put into practical use, but they have been rejected because they failed the sensory test. There is no doubt that color can make grease look beautiful, but what effect does it have on grease performance? Experts come and count the knowledge in the color of grease with you! Experts believe: "Grease is felt." From another perspective, manufacturing grease can be said to be an art. The preparation of grease is easily affected by time, temperature, mixing method, pressure, vacuum environment and other parameters. Sometimes, changing a reactor or even changing an operator can affect the grease product.
There are 17 reactors in the grease factory, and the grease produced by each reactor is a little different. This is why these reactors are used to produce special greases such as Calcium Sulfonate-based grease, composite aluminum-based grease, and polyurea grease. In addition, assign a fixed operator to heat the same kind of grease, so the effect is better. All operators must treat the heating and processing steps as carefully as they would with a child, so that they can continue to produce high-quality grease. Having said that, do you also think that grease is actually sensible? 1. Grease and color Taking into account the above reasons, we usually formulate strategies for the color, touch and taste of the grease in the promotion and use of grease. There are amber, white, black, red, blue, green, gold, silver and other colored greases on the market. Gradually, people began to form a kind of thinking that a certain color grease has a certain special function. For example, white grease is food grade; red is resistant to high temperature; blue is resistant to low temperature and is artificially synthesized; green is environmentally friendly; and silver and copper are anti-seize grease. However, not all customers in the world can accept colored greases. Compared to Asian customers, natural grease is more popular in North America. One of the reasons for this is that in the developing market, people often use low-quality Base Oil and recycled base oil to prepare cheap grease, and then add colorful dyes to cover up the shortcomings of the grease. Consumers believe that if grease does not contain dyes, it is more likely that their raw materials are fresh base oils. In addition to color, actual quality tests, hammer tests, and Timken portable machine tests can all be used as selling points, but their scientific value is still doubtful. According to customer complaint data, most of the complaints are related to sensory factors such as color, taste, touch, consistency, etc., and only a small part is related to the poor actual effect of the product. In order to understand the influence of dyes and tackifiers on the properties of greases, we have done a systematic study on grease additives.
2. Grease and dye Titanium dioxide and zinc oxide can be used to prepare food-grade white grease. The concentration of these two materials depends on the white depth of the grease, production process parameters, thickeners and base oil types. Different from the grease produced with water-white API Ⅱ base oil, Ⅲ base oil and poly-α-olefin, the grease made from API Ⅰ base oil and naphthenic base oil needs more whitening agent. When the brightener concentration is below 2%, there is no obvious effect on the properties of the grease. However, studies have found that for lithium complex grease and aluminum complex grease, the higher the concentration of the brightener, the more serious the grease's oil separation and storage hardening. Black grease additives include pitch, molybdenum disulfide, graphite, and carbon black. Asphalt has always been a material for preparing black grease. It is believed that asphalt has good adhesion on metal surfaces. However, asphalt brings hidden dangers to human health and the environment. Lubricating grease made of asphalt is easy to leave the contact surface in water or low temperature environment, and it is also easy to inhale dust in open gear devices. Greases made with other additives will not have these conditions. Molybdenum disulfide and graphite have a layered structure and have strong stability in high temperature and high pressure environments, so they can improve the properties of grease, especially in the state of elastohydrodynamic lubrication and boundary lubrication. The dye concentration in colored grease is very low. Dyes are usually made of azoquinone or anthraquinone compounds, both of which are toxic. Generally speaking, low concentrations of dyes have no effect on the properties of the grease. However, if the concentration is higher than 0.2%, the dye will weaken the corrosion inhibition performance of the grease on copper. The appearance of grease is so important to customers. What happens if grease is exposed to sunlight, high temperature, and humidity during storage and application in steel plants and metal processing plants? It has been found that grease in the sun will lose its luster and fade slowly. Under the light, products such as calcium-based grease will change from translucent amber to brown. People once tried to open a cylinder of green bio-grease and leave it for a few months, and then they were surprised to find that the grease in the cylinder had faded. Similar to this, after putting blue, green and red grease in a furnace at 250°C for 48 hours, most of the grease's color becomes dull. The three colors of grease began to emulsify after contact with water, and severely faded. 3. The dosage is moderate People often add high molecular polymers to the grease to improve the adhesion, cohesion and water resistance of the grease. Adhesiveness can be understood as the degree to which the grease tends to adhere to the metal surface; cohesion can be understood as the degree of mutual attraction between the internal molecules of the grease. Polyisobutylene, ethylene-propylene copolymer, polymethyl acrylate, polymer latex are commonly used grease tackifiers. Studies have found that a small amount of special polymers can improve the waterproof and thickening properties of grease. Too much dosage will weaken the water resistance and stability of the grease. The reason for this phenomenon may be that after the amount of polymer increases, the adhesion of the grease on the metal surface decreases, and the cohesive force inside the grease begins to take effect. Experts used an interesting field experiment to show this phenomenon. A grease with 0.5% ethylene-propylene copolymer and 0.5% polymer latex is used on drill pipe equipment with diamond bits. Compared with non-polymer sulfonic acid complex calcium grease, this grease can achieve better results. However, when the concentrations of these two polymers were increased to 1%, the effect of the grease decreased: the grease was more difficult to adhere to the drill pipe, and the situation was even worse when the drill pipe was wet. The study also found that the pumpability of the grease at low temperatures was reduced after the polymer was added. In summary, greases are also sensory. They are very sensitive to ingredients, but customers are also very sensitive. They attach great importance to the color, touch and taste of grease.
