Development status and trends of polyurethane waterproof coatings

As a multifunctional polymer material, polyurethane waterproof coating has the advantages of light waterproof layer, high strength, good elasticity, strong adhesion, high and low temperature resistance, corrosion resistance, simple construction, and easy repair. Since the birth of polyurethane waterproof coating, it has been favored and sought after by the market.
Due to the versatility and overall film-forming properties of polyurethane waterproof coating, it overcomes the shortcomings of waterproof membranes that need to be overlapped, and has an overall waterproof effect that is fully adherent to the building structure. It can meet the requirements of various building waterproofing projects and is suitable for any The construction of the base layer with complex structure is especially suitable for waterproofing and anti-seepage of roofs, basements and toilets with special-shaped structures and many pipes, ensuring the waterproof and anti-seepage quality of the entire project.
Earlier, the Central Economic Work Conference was held in Beijing. The meeting redefined infrastructure construction, including 5G base station construction, ultra-high voltage, intercity high-speed railway and urban rail transit, new energy vehicle charging piles, big data centers, artificial intelligence, industry The seven major areas of the Internet are defined as “new infrastructure construction” (referred to as new infrastructure).
Based on the excellent performance of polyurethane waterproof coatings, it has always played an important role in waterproof protection in civil buildings, municipal projects and national infrastructure. The demand for new national infrastructure has opened up a broader development space for waterproof materials.
·The development status of polyurethane waterproof coating·
Since the 1980s, with the improvement of my country’s science and technology and the progress of the chemical building materials industry, polyurethane waterproof coatings have also been rapidly promoted. The Beijing Institute of Construction Engineering and the Shanxi Chemical Industry Research Institute took the lead in polyether type coatings in 1974. The polyurethane waterproof coating has been studied theoretically and practically based on the waterproofing requirements of bathroom and toilet floors, and has been included in the national “Seventh Five-Year Plan” scientific and technological research plan.
In 1985, Shanghai Tunnel Company successfully developed the 851 tar polyurethane waterproof coating, which was widely used in waterproofing projects. This is my country’s first commercialized polyurethane waterproof coating. In 1989, the Ministry of Construction rectified and analyzed the national waterproof material market and confirmed Polyurethane waterproof coating has become a reliable waterproof material for people. After the 1990s, polyurethane waterproof coating has developed by leaps and bounds.
In 1990, the Ministry of Construction of China included polyurethane waterproof coating as one of the key projects of the “Eighth Five-Year Plan”; in 1991, Li Kunquan of Shanghai Shikewei and Professor Shen Chunlin of Suzhou Building Materials Research Institute successively developed a product code-named 911. The biggest innovation of this new type of polyurethane waterproof coating is the addition of water as a cross-linking curing agent, and no toxic substances like coal tar are added.
In 1992, the building materials industry standard JC 500-1992 was formulated and implemented in 1993, which greatly promoted the development and application of polyurethane waterproof coatings in the market; in 1998, the Ministry of Construction listed tar-type polyurethane waterproof coatings as prohibited for use in residential buildings nationwide. waterproof materials, thus prompting scientific research institutes and production units to carry out technological upgrades.
Various coal tar polyurethane substitutes quickly appeared on the market, including asphalt-modified polyurethane waterproof coatings, one-component polyurethane waterproof coatings, colored polyurethane waterproof coatings, solvent-free spray polyurethane waterproof coatings, etc.
After more than ten years of promotion and development, my country’s polyurethane waterproof coatings have gradually developed into a prosperous situation with a complete range of varieties and excellent performance. At this time, the industry standard JC 500 can no longer meet the needs of market development. In 2003, it was proposed and formulated by the China Building Materials Federation Complied with the national standard of the People’s Republic of China GB/T 19250 “Polyurethane Waterproof Coating”.
According to the tensile properties of the product, polyurethane waterproof coatings are divided into categories I and II, single-component products have been added, test items such as tear strength and wet base surface bonding strength have been added, and test methods and technical indicators have also been greatly improved. adjustment.
With the rapid development of national economic construction in the 21st century, in addition to the explosive growth of the civilian market, polyurethane waterproof coatings have also achieved leapfrog growth in the field of national key project construction, especially in key fields such as high-speed rail, subway, highway, and water conservancy projects in my country. , which has put forward higher requirements for high-performance polyurethane waterproof coatings.
Among them, in 2005, the China Federation of Building Materials Society proposed and formulated the industry standard JC/T 975-2005 “Waterproof Coating for Roads and Bridges”, and in 2011 the Ministry of Railways formulated the industry standard TB/T 2965-2011 “Railway Concrete Bridge Deck Waterproof Layer Technology”. “Conditions”, both put forward 98% solid content requirements for polyurethane waterproof coatings, which greatly promoted the healthy development of polyurethane waterproof coatings in China.
As the application of polyurethane waterproof coatings becomes more and more widespread, the products become more and more diversified. In 2013, the China Building Materials Federation proposed to revise GB/T 19250 “Polyurethane Waterproof Coatings” again. The standard divides the products into 3 types. .
Type I is usually used for general waterproofing in industrial and civil construction projects. There are two types of products, single and double components. The main index is that the tensile strength is greater than 2 MPa. Type II is usually used for waterproofing of bridge decks in non-direct traffic areas such as bridges. The main index is The tensile strength is greater than 6 MPa; type III is usually used for waterproofing of exposed traffic parts such as bridges and parking lots, and the main tensile strength is greater than 12 MPa. In addition, combustion performance and hazardous substance limit testing items have been added to the standard, promoting the wider application of polyurethane waterproof coatings in the construction field.
·Specific applications in the industry·
The construction waterproofing industry has always been a “big industry, small business” pattern. Industry concentration is lowThe development planning outline continues to list polyurethane waterproof coatings as a key product for promotion and development.
Current status of raw materials for polyurethane waterproof coating
At present, domestic polyurethane waterproof coatings mainly consist of prepolymers, plasticizers, inorganic fillers, pigments, cross-linking agents, diluents and auxiliaries. The prepolymer is made of polypropylene oxide polyol (PPG) and diisocyanate monomer by condensation. Among them, there are many domestic brands of polyether polyol. The mainstream manufacturers include Fushun Petrochemical, Tianjin Petrochemical No. 3 Plant, Blue Star Dongda, and Wanhua Chemistry, Yinuowei, etc.
Commonly used isocyanate monomers are liquefied MDI (mainly including Wanhua’s MI-50, basf’s MIPS or MI-50) and TDI (mainly including Wanhua Chemical and BASF’s T-80); plasticizers are chlorinated paraffin and Phthalate esters; the inorganic filler is mainly one or a combination of fine calcium carbonate, talc, and kaolin; the cross-linking agent is mainly MOCA from Xiangyuan Chemical; the diluent mainly uses aromatic hydrocarbon solvents, such as S100 or S150; auxiliaries Including catalysts, dispersants, defoaming agents, latent curing agents, etc.
Due to the problem of overcapacity in the construction market, serious product homogeneity and fierce competition, most manufacturers still use non-environmentally friendly materials for production due to cost considerations.
The first is toluene diisocyanate (TDI), the main production raw material, which is highly volatile, has a strong irritating smell, is toxic, and is irritating to human mucous membranes. Large doses can cause mucosal congestion and some people may be allergic; secondly, diluent , in many small cities or inland provinces, toxic solvents such as toluene and xylene are still used to reduce viscosity.
In addition, coal tar, which is banned by the state, is still secretly produced and sold. If polyurethane coatings produced using these hazardous raw materials are used indoors and underground, safety hazards and personal injuries may easily occur.
Production status of polyurethane waterproof coating
At present, domestic polyurethane waterproof coatings adopt an intermittent production method. In terms of production equipment, mainstream production companies adopt a multi-level platform to split the production process. The first-level platform is the batching and pre-dispersion kettle, the second-level platform is the dehydration kettle, and the third-level platform is the dehydration kettle. The first-level platform is a polymerization kettle, which can improve product production efficiency and reduce production energy consumption.
The measurement and transportation of the main bulk raw materials polyether polyol, plasticizer, diluent and powder can be controlled by PLC, while the additives and isocyanate monomer adopt vacuum transportation or manual feeding. This is mainly due to the reactivity comparison of isocyanate monomer. High, the storage period is short, and the amount of additives added each time is too small, so it is not suitable for tank storage.
The advantages of using PLC control are stable product quality and high production efficiency, but at the same time the equipment investment is relatively large, which is not suitable for small and medium-sized enterprises with small production capacity. Enterprises with large output generally use tank trucks to transport and store raw materials in storage tanks, which can save a large part of material costs.
·Outlook·
Development direction of polyurethane waterproof coating products
Under the dual pressure of environmental protection and security inspection, the construction waterproofing industry is accelerating the process of reshuffling and the strong are getting stronger. With the introduction of advanced market technologies and the establishment of joint ventures, foreign-funded enterprises have brought scientific management and thoughtful after-sales service. , providing opportunities for learning and reference for domestic production and operations.
For many companies, they cannot just import advanced foreign technologies, but also digest, absorb, innovate, and cultivate their own core competitiveness. The future development trends of polyurethane waterproof coatings include the following aspects:
(1) Technological innovation will become the main method of competition in the future. With the increase in labor wages, the development of polyurethane waterproof coatings that can dry quickly and reach the construction thickness at one time will surely gain favor from the market because it saves construction progress;
(2) Most polyurethane waterproof coatings currently on the market are aromatic products and cannot be directly exposed to the atmospheric environment. With the rise of the maintenance market, exposed polyurethane waterproof coatings will become the new favorite of retail channels in the future;
(3) Green environmental protection is the eternal theme of building materials. Starting from raw material selection and process improvement, we will change the production and application methods of polyurethane waterproof coatings, develop water-based, powdered, and ultraviolet-cured low-VOC coatings to effectively protect workers and workers. The health of our customers and protect our environment.
Market prospects of polyurethane waterproof coating
With the increase in investment in the country’s traditional infrastructure and new infrastructure, waterproof materials are also facing new opportunities. Among them, the growth rate of subway investment will reach more than 20% from 2019 to 2025. According to the empirical data of waterproof materials companies, subway construction is mainly underground projects, and the unit consumption of waterproof materials is high. Subway platforms (per block) and subway tunnels (per kilometer) The value of the waterproof materials used is about NT$1.5 million/NT$1 million respectively.
Summary
In the next few years, driven by projects such as underground comprehensive pipe corridors, rail transit construction, affordable housing construction, and upgrading and renovation of existing buildings, the waterproofing industry will still be in a medium-to-high-speed growth stage in the short and medium term, and the demand for waterproofing materials will surely remain a certain growth rate.
In addition, with the establishment and improvement of the home decoration market and the rise of the maintenance market, waterproof coatings, which are the main products in retail channels, are growing rapidly in the sales market, which is bound to drive the growth of polyurethane waterproof coatings.