The early formula of the three anti-adhesive is polyurethane. Now it is mainly based on acrylate. One kind is silicon-containing material. If it is a three-proof glue of this material, it cannot be used on PCB with unsealed relay, because this The three anti-adhesives will volatilize into Sio2 and attach to the contacts of the relay, causing the relay to lose its conductivity.
01
Acrylic acid: (strongly corrosive, moderately toxic. Its aqueous solution or high concentration of vapor will irritate the skin and mucous membranes.)
Acrylic acid is an organic compound of the chemical formula C3H4O2, an important organic synthetic raw material and a synthetic resin monomer, and is a vinyl monomer having a very fast polymerization rate. It is the simplest unsaturated carboxylic acid consisting of a vinyl group and a carboxyl group. Pure acrylic acid is a colorless, clear liquid with a characteristic pungent odor. It is miscible with water, alcohol, ether and chloroform and is prepared from propylene obtained from a refinery. Most are used to make acrylates such as methyl acrylate, ethyl ester, butyl ester, and hydroxyethyl ester. Acrylic acid and acrylate can be homopolymerized and copolymerized, and the polymer is used in industrial sectors such as synthetic resins, synthetic fibers, superabsorbent resins, building materials, and coatings.
Chemical properties:
1, flammable, its vapor and air can form an explosive mixture, in case of fire, high heat can cause combustion and explosion. It can react with oxidants. In case of high heat, polymerization may occur, releasing a large amount of heat to cause container rupture and explosion. In case of heat, light, moisture, peroxide and iron, it is easy to self-polymerize and cause an explosion.
2. Combined reaction with double bond and carboxyl functional group, addition reaction, functional group reaction and transesterification reaction, long preparation of polycyclic and heterocyclic compounds, easy hydrogen reduction to propionic acid, decomposition of alkali to formic acid and acetic acid .
3. Strong acidity. Corrosive. Chemically active. Easy to polymerize into a transparent white powder. Propionic acid is produced upon reduction. 2-chloropropionic acid is formed when added with hydrochloric acid. Acrylic acid can undergo a characteristic reaction of a carboxylic acid, and a corresponding ester can also be obtained by reacting with an alcohol. After the acrylic acid and its esters are themselves or mixed with other monomers, polymerization occurs to form a homopolymer or a copolymer. The monomers which are usually copolymerizable with acrylic acid include amides, acrylonitrile, vinyl-containing, styrene and butadiene. These polymers are used in the production of a wide variety of plastics, coatings, adhesives, elastomers, floor polishes and coatings.
4. This product has strong corrosiveness and moderate toxicity. Its aqueous solution or high concentration of vapor can irritate the skin and mucous membranes. The oral LD50 of rats was 590 mg/kg. Be careful not to come into contact with acrylic acid solution or steam. Wear overalls and work caps, safety glasses and rubber gloves when handling. Production equipment should be sealed. Work and storage should be well ventilated.


02
Polyurethane: (smell)
Polyurethane is a kind of polymer containing -NHCOO-repeating structural unit in the main chain, the abbreviation PU, which is formed by polymerization of isocyanate (monomer) and hydroxy compound. Due to its strong polar urethane group, it is insoluble in non-polar groups and has good oil resistance, toughness, abrasion resistance, aging resistance and adhesion. Different materials can be used to make materials suitable for a wide temperature range (-50 to 150 ° C), including elastomers, thermoplastic resins and thermosetting resins. It is not resistant to hydrolysis at high temperatures and is not resistant to alkaline media. Including rigid polyurethane plastic, flexible polyurethane plastic, polyurethane elastomer and other forms, and divided into thermoplastic and thermosetting two categories. The raw materials are generally presented in a resin state. In addition to being a single component, polyurethane can also be blended with other materials to form a composite.
The application fields of polyurethane coatings are: vehicle coating, ship, wood, building coating, anti-corrosion coating, surface coating of aircraft, plastic, rubber, leather, etc.
Waterborne polyurethane coating - water is the main medium, with low VOC content, low or no environmental pollution, convenient construction, etc. It is one of the main substitutes for solvent-based coatings. Has been widely used in many fields, such as: (1) wood lacquer and wood floor lacquer; (2) paper coating; (3) architectural coating; (4) leather coating; (5) fabric coating, etc. .




03
Silicone:
Silicone, that is, an organosilicon compound, refers to a compound containing a Si-C bond and at least one organic group is directly bonded to a silicon atom, and it is customary to use an organic group and a silicon atom through oxygen, sulfur, nitrogen, and the like. The attached compound is also considered to be an organosilicon compound. Among them, polysiloxanes composed of silicon-oxygen bonds (-Si-O-Si-) are the most widely studied and most widely used organosilicon compounds, accounting for more than 90% of the total dosage. .
Silicone
Silicone is a highly crosslinked network of polyorganosiloxanes, usually methyltrichlorosilane, dimethyldichlorosilane, phenyltrichlorosilane, diphenyldichlorosilane or methylphenyl Various mixtures of dichlorosilane are hydrolyzed at a lower temperature in the presence of an organic solvent such as toluene to obtain an acidic hydrolyzate. The initial product of hydrolysis is a mixture of cyclic, linear and crosslinked polymers, usually also containing a significant amount of hydroxyl groups. The hydrolyzate is washed with water to remove the acid, and the neutral condensate is thermally oxidized in the air or further polycondensed in the presence of a catalyst to finally form a highly crosslinked stereo network structure.
Silicone is a thermoset plastic and one of its most outstanding properties is its excellent thermal oxidative stability. After heating at 250 ° C for 24 hours, the silicone weight loss is only 2 to 8%. Another outstanding property of silicone is its excellent electrical insulation properties, which maintain its good insulation properties over a wide temperature and frequency range.
In view of the above characteristics, silicone resin is mainly used as an insulating varnish (including varnish, enamel, paint, dipping varnish, etc.) to impregnate H-class motor and transformer coil, and is used to impregnate glass cloth, glass cloth and asbestos cloth to make motor sleeve. Pipes, electrical insulation windings, etc. Bonding mica with silicone insulating varnish can produce a large area of mica sheet insulation material, which is used as the main insulation of high voltage motors. In addition, silicone can also be used as a heat-resistant, weather-resistant anti-corrosion coating, metal protective coating, construction waterproof and moisture-proof coating, mold release agent, adhesive and secondary processing into silicone plastic for electronic, electrical and defense industries. In addition, it is used as an insulating material for semiconductor packaging materials and electronic and electrical components.
Silicone resins can be roughly classified into silicone insulating varnishes, silicone coatings, silicone plastics and silicone adhesives according to their main uses and cross-linking methods.
1. Silicone waterproofing agent can be used together with sodium nitrite antifreeze during construction in winter.
2, silicone waterproofing agent is a general chemical, construction workers should be careful not to splash on the face during storage and use, especially not splash into the eyes, otherwise immediately rinse with plenty of water or ask a doctor. Wear protective gloves, protective glasses, and work clothes to avoid contact with the skin.
3, silicone waterproofing agent This agent should not be exposed to zinc, aluminum, tin and other active metals during transportation and use. It should not be stored in iron metal containers to avoid deterioration of the product caused by chemical reaction and corrosion of the container.


04
Epoxy resin
Epoxy resin refers to an organic compound containing two or more epoxy groups in a molecule, and their relative molecular masses are not high except for a few. The molecular structure of the epoxy resin is characterized by the presence of an active epoxy group in the molecular chain, and the epoxy group may be located at the end, in the middle or in a ring structure of the molecular chain. Since the molecular structure contains an active epoxy group, they can be cross-linked with various types of curing agents to form an insoluble polymer having a three-dimensional network structure. A polymer compound containing an epoxy group in a molecular structure is collectively referred to as an epoxy resin. The cured epoxy resin has good physical and chemical properties. It has excellent bonding strength to the surface of metal and non-metal materials, good dielectric properties, small deformation shrinkage, good dimensional stability, high hardness and flexibility. It has good properties and is stable to alkali and most solvents. It is widely used in various departments of national defense and national economy for casting, dipping, laminating, bonding, coating and other purposes.
Electronic and electrical applications
Due to its many unique advantages, such as high insulation performance, high structural strength and good sealing performance, epoxy resin has been widely used in the insulation and packaging of high and low voltage electrical appliances, motors and electronic components, and has developed rapidly. Mainly used:
1. Casting of electrical and motor insulation packages. The manufacture of integral fully sealed and insulated packages for high and low voltage electrical appliances such as electromagnets, contactor coils, transformers, dry transformers, etc. It has developed rapidly in the electrical industry. From atmospheric casting, vacuum casting has evolved to automatic pressure gel forming.
2. It is widely used for potting insulation of devices equipped with electronic components and circuits. Has become an indispensable important insulation material for the electronics industry.
3. Electronic grade epoxy molding compound is used for plastic packaging of semiconductor components. To develop very fast. Due to its superior performance, it has a tendency to replace traditional metal, ceramic and glass packaging.
4. Epoxy laminated plastics are widely used in electronics and electrical appliances. Among them, the development of epoxy copper clad laminates is particularly rapid and has become electricity.
One of the basic materials of the sub-industry.
In addition, epoxy insulating coatings, insulating adhesives and electrical adhesives are also used in a large number of applications.


05
Similar characteristics and differences between polyurethane paint and acrylic:
Polyurethane lacquer and acrylic urethane lacquer are common products in industrial anti-corrosion coatings. They are widely used in applications, and many users are easily confused. In fact, the two are different paints, have many similar characteristics, and also have different places.
Similar characteristics:
1. Decorative: Polyurethane lacquer and acrylic urethane lacquer are topcoats with various colors and adjustable gloss, which have excellent decorative effects.
2, matching: the matching primer and intermediate paint are the same, generally equipped with epoxy primer, epoxy cloud iron intermediate paint, etc., excellent adhesion.
3. Construction: The construction method is the same, mainly by spraying and brushing. The two are two-component paints. The curing agent and diluent are mixed before painting, and the operation methods are similar.
The main difference:
1. Composition difference: Polyurethane paint generally consists of two parts, an isocyanate prepolymer and a hydroxyl-containing resin. It is usually called a curing agent component and a main component.
2, weather resistance: polyurethane paint weather resistance is poor, outdoor use for about 1 year will lose light fade or even powder; acrylic polyurethane paint has strong weather resistance.
3, the use of the environment: polyurethane paint is mainly used for indoor mechanical equipment, iron frame, pipeline anti-corrosion; acrylic polyurethane paint for outdoor steel structure, construction, machinery, pipe coating.
Polyurethane lacquer and acrylic urethane lacquer are analyzed in combination with their main differences. It is necessary to judge whether the use environment is indoor or outdoor, painted workpieces, and design requirements. Both are widely used in the market, but the prices vary greatly, so choosing the right paint can save costs.