What material is polyurethane made of? What are its advantages for water tank insulation?

Polyurethane

polyurethanes

Polyurethane material is currently the best thermal insulation material in the world. A type of polymer whose main chain contains -NHCOO- repeating structural units. The English abbreviation is PU. It is polymerized by isocyanate (monomer) and hydroxyl compound. Because it contains highly polar urethane groups and is insoluble in non-polar groups, it has good oil resistance, toughness, wear resistance, aging resistance and adhesion. Materials that adapt to a wide temperature range (-50~150℃) can be made from different raw materials, including elastomers, thermoplastic resins and thermosetting resins. It is not resistant to hydrolysis at high temperatures and is not resistant to alkaline media.

Commonly used monomers include toluene diisocyanate, diisocyanate diphenylmethane, etc. Polyols are divided into three categories: simple polyols (ethylene glycol, glycerol, etc.); polyester oligomers containing terminal hydroxyl groups, used to prepare polyester polyurethane; polyether oligomers containing terminal hydroxyl groups, used to prepare Preparation of polyether polyurethane. Polymerization methods vary with material properties. When synthesizing elastomers, low molecular weight diols are first prepared, and then reacted with excess aromatic isocyanates to generate isocyanate-terminated prepolymers, which are then chain extended with butanediol to obtain thermoplastic elastomers; if aromatic diamines are used Chain extension and further cross-linking yield cast elastomers. The prepolymer is chain-extended with hydrazine or diamine to obtain elastic fibers; the prepolymer with a large excess of isocyanate is mixed with a catalyst and a blowing agent to directly obtain rigid foam. For example, by mixing monomers, polyethers, water, catalysts, etc., flexible foams can be obtained in one step. Monomers react with polyols in a solution to obtain coatings; adhesives are composed of polyisocyanate monomers and low molecular weight polyesters or polyethers that are mixed and reacted during use.

Polyurethane elastomers are used as rollers, conveyor belts, hoses, auto parts, shoe soles, synthetic leather, wires and cables, and medical artificial organs; soft foams are used as padding for vehicles, homes, and clothing. , rigid foams are used for thermal insulation, sound absorption, packaging, insulation and low-foaming synthetic wood, coatings are used for high-end vehicles, furniture, wood and metal protection, pool dams and building anti-leakage materials, and fabric coatings, etc. The adhesive has good adhesion to metal, glass, ceramics, leather, fibers, etc. In addition, polyurethane can also be made into emulsions, magnetic materials, etc.

1. Applications in daily life are:

Furniture industry applications

1. Sofa, 2. Mattresses, 3. Adhesives, 4. Coatings, 5. Paints, 6. Seat armrests

Household appliance applications

1. Refrigerators, freezers, disinfection cabinets, water heaters, etc., 2. Wire and cable sheaths, 3. Electrical appliances Insulating paint, 4. Washing machine electronic components and waterproof potting glue

Construction industry application

1. Building wall insulation, 2. Roof waterproofing, 3. Sealant, 4. Adhesive Mixture, 5. Interior and exterior wall paint, 6. Floor paint, 7. Synthetic wood, 8. Waterproof and leak-proofing agent, 9. Plastic floor

Transportation industry application

1. Automobile Interior parts: seats, armrests, headrests, inner door panels, instrument panels, steering wheels, shock absorbers; exterior parts: bumpers, fenders, 2. carpet lining, paint, 3. thermal insulation parts, pipes Road, 4. Sealing gasket, 5. Anti-skid chain

Shoemaking and tanning industry applications

1. Sole, 2. Adhesive, 3. Leather finishing agent, 4 .Artificial leather, synthetic leather coating

Application in sports industry

Plastic sports venues (basketball, volleyball, badminton, tennis), sportswear (dance wear, swimsuit,); sports shoes , Scooter

2. The specific applications of various polyurethane materials are:

1. PU soft foam Flexible PU

Cushions - such as seats, Sofas, mattresses, headrests, etc., polyurethane soft foam is a very ideal cushion material, and cushioning is also the application field with the largest amount of soft foam;

Sound-absorbing material - open-cell polyurethane soft foam It has good sound absorption and shock absorption function and can be used as indoor sound insulation material;

Fabric composite materials - shoulder pads, bra sponges, cosmetic sponges; toys

2. PU hard foam ( Rigid PU)

Refrigerating and refrigeration equipment - such as refrigerators, freezers, cold storages, refrigerated trucks, etc. Polyurethane rigid foam is the most ideal insulation material for refrigeration and refrigeration equipment;

Industrial equipment insulation - Such as storage tanks, containers, pipelines, etc.;

Building materials - In developed countries in Europe and the United States, polyurethane rigid foam for construction accounts for about 70% of the total consumption of rigid foam, which is the largest amount of rigid foam used in refrigerators, freezers, etc. More than double; in China, the application of hard foam in the construction industry is not as common as in Western developed countries, so the development potential is very large;

Imitation wood - high density (density 300~700kg/ m3) Polyurethane rigid foam or glass fiber reinforced rigid foam is a structural PU foam plastic, also known as imitation wood. It has the characteristics of high strength, good toughness, dense and tough crust, simple molding process, and high production efficiency. Its strength is comparable to natural wood. High, the density can be lower than that of natural wood, and it can be used as a substitute for wood in high-end products.

Flower industry - PU flower pots, flower arrangement mud, etc.

3. PU semi-rigid foam (Semi-rigid PU)

Energy-absorbing foam - —Energy-absorbing foam has excellent shock absorption and buffering properties, good compressive load resistance and deformation recovery properties. Its most typical application is in the preparation of automobile bumpers;

Self-skinning foam Integral Skin Foam - used to prepare functional parts and interior trim parts such as automobile steering wheels and armrests. Self-skinned foam products usually use reaction injection molding (RIM) processing technology;

4. Polyurethane elastomers (PU Elastomers)

Casting polyurethane elasticity Thermoplastic polyurethane elastomer (referred to as CPU) - is the most widely used and produced type of polyurethane elastomer;

Thermoplastic polyurethane elastomer (referred to as TPU) - thermoplastic polyurethane elastomer accounts for approximately 10% of polyurethane elastomers. About 25% of the total amount of elastomers;

Mixed polyurethane elastomer (referred to as MPU) - accounts for about 10% of the total amount of polyurethane elastomers.

Microcellular elastomers - The most typical application of polyurethane microcellular elastomers is in shoemaking.

Applications in mining and other industries - screen plates, shaking tables, etc.

Applications in the machinery industry - rubber rollers, tapes, seals, etc.;

Applications in the automotive industry - tires, seals, bumpers, shock absorbing pads, pipes, transmission belts, shock absorbing springs, etc.;

Applications in the light industry - polyurethane shoe sole materials, polyurethane Synthetic leather, polyurethane fiber;

Applications in the construction industry - thermal insulation materials, waterproof materials, paving materials, potting materials, etc.

5. Polyurethane sole material (Shoe Sole)

Polyurethane sole has many advantages: low density, soft texture, comfortable and light to wear; good dimensional stability, long storage life; excellent Wear resistance, flex resistance; excellent shock absorption and anti-skid properties; good temperature resistance; good chemical resistance, etc. Polyurethane is mostly used to make high-end leather shoes, sports shoes, travel shoes, etc.

6. Polyurethane slurry

It is divided into two categories: wet method and dry method. It is a polymer solution system with a transparent or slightly turbid appearance and a solid content of about ( 30-35), that is to say (65-70) is the solvent. Simply put, 1 ton of slurry contains (650-700) kilograms of solvent. For the dry method, it contains so much toluene and methyl ethyl ketone. , the amount of toluene is larger, because toluene has better solubility. For the wet method, it contains 650-700 kg of pure DMF. Therefore, for the slurry, the price changes of toluene and DMF have a great impact. The reason for the cost of slurry is very simple, and the dosage accounts for a large proportion.

Polyurethane slurry is used as coating to prepare polyurethane synthetic leather and artificial leather. Polyurethane synthetic leather has a soft, natural luster, soft hand feel, and a strong leather-like appearance. It has excellent mechanical properties such as excellent adhesion to the base material, anti-wear, flex resistance, anti-aging, and good mold resistance. It also has It has the advantages of good cold resistance, breathability, washability, easy processing, and low price. It is the most ideal substitute for natural leather and is widely used in clothing, shoemaking, luggage, furniture, sports and other industries. It can be used as a substitute in all areas where dermis is used, and it can also be used in areas where dermis cannot be used. The price of dermal leather is easily affected by animal (cattle, sheep, pigs, etc.) prices and diseases (such as mad cow disease).

Dry polyurethane slurry - During the application process, the solvent in the slurry is evaporated by heating and evaporation. Most of the solvents are toluene and methyl ethyl ketone. The evaporated solvent cannot be recovered, which not only pollutes the environment, and also creates unnecessary waste.

Wet polyurethane slurry - because the processing process uses DMF to extract water (the reason is that DMF has unlimited solubility with water), it is more environmentally friendly, and the synthetic leather produced has good It has moisture-permeable and breathable properties, feels soft, plump and light, and has the style and appearance of natural leather, so its development speed is extremely amazing.

7. Polyurethane fiber (Spandex, referred to as spandex)

The excellent properties of spandex: outstanding high resilience. The high resilience of spandex is unmatched by all current elastic fibers. Its elongation at break is greater than 400 and can reach up to 800. Even at 300 tensile deformation, the rebound recovery rate is still above 95; excellent tensile strength and tear resistance; strong weather resistance and ultraviolet radiation resistance; Resistant to chemicals and washing; has good affinity with dyes.

Spandex Lycra has been widely used in textiles. It is a new type of textile material with high added value. There are four main forms of use: bare yarn, core-spun yarn, covered yarn, and twisted yarn. . Such as stockings, swimsuits, dance suits, pure cotton-coated silk, clothing, etc. In traditional textiles, just adding less than 5% spandex can greatly improve the quality of traditional fabrics, showing softness, comfort, and beauty. , elegant style.

8. Polyurethane coatings (PU Coatings)

The main application areas of polyurethane coatings are: vehicle coating, ships, wood, building coating, anti-corrosion coating, aircraft, plastics , rubber, leather surface coating, etc.

Water-based polyurethane coating - using water as the main medium, has the characteristics of low VOC content, low or no environmental pollution, and convenient construction. It is one of the main alternatives to solvent-based coatings. It has been widely used in many fields, such as: (1) wood paint and wood floor paint; (2) paper coating; (3) architectural coating; (4) leather coating; (5) fabric coating, etc. .

9. Polyurethane adhesives (PU Adhesives)

Polyurethane adhesives contain highly polar and chemically active -NCO- (isocyanate), -NHCOO- (aminomethyl) Acid ester group), has excellent chemistry with base materials containing active hydrogen, such as foam, plastic, wood, leather, fabric, paper, ceramics and other porous materials, as well as metal, glass, rubber, plastic and other materials with smooth surfaces. Adhesion;

It has excellent shear strength and impact resistance, is suitable for various structural bonding fields, and has excellent flexibility;

Polyurethane adhesive The adhesive has excellent rubber properties and can adapt to the bonding of substrates with different thermal expansion coefficients. It forms a soft-hard transition layer between the substrates, which not only has strong adhesion, but also has excellent buffering and shock-absorbing functions;

The low-temperature and ultra-low-temperature performance of polyurethane adhesives exceeds that of all other types of adhesives;

Water-based polyurethane adhesives - Water-based polyurethane adhesives have the characteristics of low VOC content, low or no environmental pollution, and non-flammability. , is the key development direction of polyurethane adhesives.

10. Polyurethane sealant (PU Sealants)

Sealants are materials used to fill gaps (holes, joints, seams, etc.) and have both bonding and sealing functions. . Polyurethane sealant, silicone sealant, and polysulfide sealant constitute the three major varieties of high-end sealants at present.

Polyurethane sealants are widely used in civil construction, transportation and other industries:

Applications in construction - filling and sealing of doors, windows, glass, etc.;

Applications in civil engineering - caulking and sealing of highways, bridges, runways, etc.;

Applications in automobiles - assembly and sealing of windows (mainly windshields).

Polyurethane sealant has many excellent properties, including: (1) wide adjustable performance range and strong adaptability (2) good wear resistance; (3) high mechanical strength; (4) bonding performance Good; (5) Good elasticity, excellent recovery, and can be used for dynamic joints; (6) Good low-temperature flexibility; (7) Good weather resistance, with a service life of 15 to 20 years; (8) Good oil resistance; (9) Resistant to biological aging; (10) Moderately priced.

What we usually call TDI, MDI, AA and other products should be polyurethane raw materials and cannot be called polyurethane products. Polyurethane raw materials mainly include: isocyanate, polyester polyol (generated by the reaction of polyol and polybasic acid, commonly used polybasic acid is adipic acid, commonly used polyols include 1,2 butanediol, ethylene glycol, etc.), polyether polyol ( Commonly used ones include PPG, POP, PTMEG, etc.), solvents (commonly used ones include DMF, TOL, MEK, etc.), chain extenders (commonly used ones include BDO), and various additives.

At present, the total demand for polyurethane in the world is more than 8 million tons, of which about 2.7 million tons are in the United States, about 2.5 million tons in Europe, and about 2.3 million tons in the Asia-Pacific region. At present, the average annual growth rate of global polyurethane foam demand has remained at around 7, with the growth rate in South Asia even higher than this number. It is estimated that in 2005, the total demand for polyurethane foam in the world will exceed 10 million tons. The polyurethane industry in the Asia-Pacific region will become a tripartite force with Europe and the United States. China and Japan have the largest output and demand in this region.

In 2001, the output of polyurethane products in my country reached about 1 million tons.

During the "Ninth Five-Year Plan" period, the average annual growth rate remained above 10, and consumption is expected to reach 1.4 million tons in 2005.