Hydrocarbon cleaner
Hydrocarbon cleaner
The distillate solvents obtained by distillation of crude oil are called petroleum series, petroleum series hydrocarbon, hydrocarbon series, hydrocarbon, industrial gasoline, etc., the definition of which is not clear so far. Hydrocarbons, as their name suggests, are simply compounds made up of two elements. In the past, the lamp oil obtained by simple distillation of crude oil was used as cleaning agent, but it has been gradually not used because of its bad smell, ignition and dryness.
Hydrocarbon cleaning agent has good environmental protection characteristics and cleaning ability, and has gradually become one of the important industrial cleaning agents.
Related knowledge
CFC-113 (Freon) and 1.1.1- trichloroethane (ethane), which were once widely used in the cleaning industry, have been completely banned from production, import and use. Alternatives such as chlorine cleaners (trichloroethane, trichloroethylene, dichloromethane, etc.), drainage cleaners and hydrocarbon cleaners are still in use. For the majority of users, it can be assumed that these users have switched to chlorine cleaners for some time due to the advantage that chlorine cleaners can be used with minor modifications to the original equipment.
However, chlorine cleaning agent due to toxic, environmental control is very strict, and because of the ISO14000 series of chlorine cleaning agent has limited requirements, enterprises in order to obtain ISO14000 certificate, now have begun to use hydrocarbon cleaning agent and water system cleaning agent. And water cleaning agent equipment investment cost is high, not easy to dry, cleaning products often rust, spots, also need to consider drainage problems, and the lack of water resources in China and other problems, now the manufacturers have gradually begun to study its substitutes.
On the other hand, combustibility and non-combustibility need to be considered separately when using non-stream cleaning agents. Hydrocarbon system has flammability, and has the weakness of not drying easily compared with chlorine system cleaning agent. However, these aspects have been gradually compensated in cleaning equipment, and it is predicted that hydrocarbon cleaning agents will gradually become the mainstream of today's alternative cleaning agents. So this paper focuses on hydrocarbon cleaning agent and equipment.
Type of cleaning agent
The distillate solvents obtained by distillation of crude oil are called petroleum series, petroleum series hydrocarbon, hydrocarbon series, hydrocarbon (hydrocarbon), industrial gasoline, etc., the definition of which is still unclear. Hydrocarbons, as their name suggests, are simply compounds made up of two elements. In the past, the lamp oil obtained by simple distillation of crude oil was directly used as cleaning agent, but it was gradually not used because of its odor, ignition and dryness.
Most hydrocarbon cleaning agents in use today are not refined products of simple distillation of crude oil, but are chemical compounds or products that have undergone advanced refining. Hydrocarbon cleaning agent from good, small odor. The lamp oil was extracted by molecular sieve and the boiling point was adjusted by distillation. There are also single-component substances.
Isomer hydrocarbon: A saturated chain hydrocarbon with the structural formula CnH2n+2. In terms of chemical structure, normal hydrocarbon series, isomeric hydrocarbon series, cycloalkanes and aromatic hydrocarbons can be divided into four types.
Normal hydrocarbon: saturated chain hydrocarbon with structural formula CnH2n+2. The stability ratio of straight chain hydrocarbon, isomeric hydrocarbon has branch chain, its safety is good, small odor. Most of them are synthetic.
Cycloalkanes: saturated chain hydrocarbons with the formula CnH2n. The number of carbon atoms is different, there may be simple cyclic alkane, cycloalkanes with side chain, etc. From the perspective of structure, the solubility of chain hydrocarbon is better, but the stability, odor is slightly poor. It is generally obtained by distillation of crude oil containing more naphthenes or by adding nuclear water to aromatic system.
Aromatic hydrocarbon: Containing benzene ring, strong solubility, due to concerns about its toxicity is now less used.
With the continuous development of hydrocarbon cleaning agent market, cleaning field continues to expand, functional hydrocarbon cleaning agent should be launched according to the market demand, on the basis of the original hydrocarbon cleaning agent oil degreasing, can be adjusted according to different cleaning needs, according to the different cleaning stains, it can be divided into the following categories:
Dehydration type hydrocarbon cleaning agent: can be cleaned to remove moisture on the workpiece, cutting fluid, water based cleaning agent, etc.
Antirust hydrocarbon cleaning agent: cleaning and antirust, can be applied to iron parts, carbon steel and other easy to rust metal cleaning, rust prevention period up to 15-90 days.
In addition to flux type hydrocarbon cleaning agent: cleaning electronic instruments, PCB circuit boards and other parts of the flux, oil, dust, etc.
In addition to carbon ash type hydrocarbon cleaning agent: cleaning batteries, capacitors and other cylindrical stamping tensile workpiece carbon black, powder, oil, etc.
Wax removal hydrocarbon cleaning agent: used for cleaning hardware sanitary ware, watch electroplating, jewelry processing, lighting manufacturing and other workpiece polishing wax
In addition to resin hydrocarbon cleaning agent: cleaning parts and equipment on the oil, natural resin and synthetic resin.
Cleaning principle
Cleaning mechanism
The cleaning principle of non - drainage cleaning agent is simply to clean according to the solubility of solvent. The degreasing mechanism based on solubility of grease or oil contamination is the principle of similar phase solubility. Gasoline, lamp oil and other hydrocarbons are easy to dissolve heavy oil, other hydrocarbons, and similar halogenated hydrocarbons (carbon tetrachloride, trichloroethane, etc.) miscible. This is also the basis for the miscibility of water energy and compounds with OH structures similar to water, such as R-COOH (low fatty acids) and R-OH (low alcohols). The solubility of dissimilar liquids is closely related to surface tension and interfacial tension. For example, the surface tension of benzene, naphthene and other solvents is little different from that of tar and lubricating oil, and the interfacial tension between them is approximately easy to be miscible. For the solubility of solvents to grease or oily dirt, the lower the temperature of solute separation, the greater the solubility of solute.
KB value
The KB value is the value used by the spray painting and coating industry to represent the solubility of tenna water, and refers to the ml number of diluent required to precipitate kauri gum from 120g standard kauri Gum-butanol solution at 25℃. The higher the KB value, the better the solubility. The determination of solvent solubility for cleaning used to take KB value as an index, but KB value refers to the solubility of resin, and cleaning force has no direct relationship, so it is difficult to be used as a benchmark.
SP value
The solubility index of cleaning solvent is the solubility parameter SP value. SP value is expressed by the following formula:
SP value: δ=(△E/V) △E: evaporation energy V: molar volume
Substances with similar SP values have similar agglutination energy, so they are easy to dissolve each other. This phenomenon is the empirical rule of similarity dissolution. The SP values of each substance are shown on the other page. General hydrocarbon cleaning agent SP value is 7 ~ 8, this value is consistent with the SP value of processing oil (7 ~ 8), so it is easy to dissolve, and has a high cleaning power. However, the SP value of the resin is far away, so it is not easy to erode these materials. At the same time for the resin containing dirt, alcohol solubility is poor cleaning effect. SP value can be used as an indicator when choosing cleaning agent, but it is dangerous to judge only by the value, so it must be evaluated by the cleaning performance experiment with actual polluted oil.
Physical rationality
Besides the dissolution force of solvent, there are also physical forces such as heat, agitation, friction, compression, decompression, grinding and ultrasonic. Not only consider one of the factors, but all factors into consideration in order to improve the cleaning effect. Table 2 is a summary of factors affecting cleaning power.
Factors affecting cleaning power
Chemical power: solubility... Interfacial tension... Surfactant (auxiliaries) chemical reaction power...
Physical force: heating... Promote the reaction of other cleaning factors, the physical change of the dirt, the change of the physical properties of the cleaned things. Ultrasound... Cavitation caused by ultrasound, acceleration, strong peeling and dispersion caused by direct flow. Stir... In order to promote the mixing of the cleaned surface and the fresh cleaning solution, the dirt after homogenization (shaking, improving the cleaning effect, mechanically promoting the stripping of the dirt on the cleaned surface, dispersing the stripping rotation) is in the cleaning solution to prevent the re-adhesion of the cleaning surface. Decompress... The decompression fluid to fine penetration, so that the dirt expansion to remove. According to the above factors affecting the cleaning force, the design and configuration of hydrocarbon cleaning equipment should be targeted, such as the configuration of the main function of the cleaning tank is usually as follows: Working principle: the first stage: First by the operator will clean the product into the washing basket, and then the washing basket into the equipment feeding area, through the operator control mechanical arm will wash the basket referred to the main cleaning tank. At this time, the cylinder drive tank cover automatically closes the cleaning tank, and the vacuum degassing system starts to exhaust the air in the tank. In the vacuum state, the gas in the narrow gap of the product to be cleaned and the gas contained in the cleaning agent can be extracted, ultrasonic start, swing device start, drive the washing basket rotation, so that the cleaning agent can be fully cleaned; After the set time, the vacuum is released, the cylinder is driven to open the lid, and the mechanical arm raises the washing basket to enter the second slot for cleaning. As for the need for several slots for vacuum cleaning, it is necessary to decide according to the oil, impurities and other substances on the surface of the product and the output of the product.
Cleaning (example of five-slot cleaning machine)
Sequence division Cleaning engineering Cleaning Method Cleaning medium Cleaning time Using temperature filtration method heating method vacuum degassing Remarks
1 Initial washing ultrasonic immersion washing throwing + rotating carbonized water model optional 3-30min can adjust the normal temperature - 100℃ root selection of cleaning liquid can adjust the cylinder filter heat conduction oil heating has forced cooling
2 Fine washing ultrasonic immersion washing throwing + rotating carbonized water model optional 3-30min can adjust the normal temperature - 100℃ root selection of cleaning liquid can adjust the cylinder filter heat conduction oil heating has forced cooling
3 bleaching ultrasonic immersion washing throwing + rotating carbonized water model optional 3-30min can adjust the normal temperature - 100℃ root selection of cleaning liquid can adjust the cylinder filter heat conduction oil heating forced cooling
4 5 cutting liquid + vacuum drying high speed air knife + rotary vacuum drying high speed hot air 3-30min can adjust RT-150℃ medium efficiency filter electric heating exhaust has
6 back to vacuum distillation recovery coking water model an alternate sections of distillation recycling more -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- heat conduction oil heating -- -- -- -- --
Cleaning agent characteristics
characteristic
It has already been mentioned that hydrocarbon cleaning agents can be divided into normal hydrocarbon, isomeric hydrocarbon, cycloalkanes and aromatic hydrocarbons. Its characteristics are:
Strong cleaning force on metal working oil → good cleaning effect on fine seam and fine hole part due to small surface tension.
The solubility of liquid crystal fouling, especially biphenyl fouling is good.
Recently, a variety of filth (water-soluble processing oil, login, flaks) with cleaning agents.
It does not corrode metal.
The effect on the resin is small - normal hydrocarbon, isomeric hydrocarbon, cycloalkanes.
Most hydrocarbon cleaning agents can be recycled by distillation and are economical to use.
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