Quality problems and countermeasures of hollow glass in general buildings
In the general building envelope structure, although the window wall area ratio is only 30%-50%, in the entire building energy consumption, the heat loss through the outer window conduction, radiation and cold air infiltration, accounting for the entire building heating energy Half of the consumption, the heat loss of the glass curtain wall is mainly transmitted and radiated through the glass. Therefore, the use of energy-saving glass is an important technical way to achieve building energy efficiency.
With the implementation of building energy-saving regulations and building energy-saving management, restrictions and prohibition of the use of non-insulated glass single-frame double glass door and window technology has greatly promoted the development of insulating glass, and its market total has grown rapidly, but with the hollow With the increase of glass manufacturers and the increase of production capacity, the competition is fierce. Under the market environment where some builders are too low-cost, the disadvantages of inferior and low-cost insulating glass entering the construction market are prominent. If they are allowed to develop improperly, they will be damaged. In the implementation of building energy conservation, it will also attract complaints from owners and occupants. Sealant is the key material to ensure the quality of insulating glass seals. The quality of product rectification should start from the source of product bonding and sealing assembly, strengthen the implementation of standards and promote product quality certification. Strengthen the supervision of the terminal market of construction products.
Manufacturing elastic sealant quality status
The essence of insulating glass is the double-sealed glass sealed at the periphery. It appeared earlier in the mid-19th century. It was inefficient at the beginning and the product was expensive. It was not until the development and application of low permeability elastic sealant in the 1970s that the adhesive seal appeared. The molded insulating glass is put into industrial production by the automatic injection sealing process and the room temperature rapid curing technology. The basic function of the sealant is to bond the two pieces of glass into a non-separated unit body to ensure the inner space gas is permanently dried. Its bond stability, the elasticity of the pressure difference displacement deformation and the ultra-low permeability directly determine the functional aging of the product. The basic performance requirements and testing requirements have been specified by the national industry standard JC/T468 "Elastic Sealant for Insulating Glass". .
According to the level of management and equipment technology, China's insulating glass production enterprises can be divided into two categories, one is to establish a sound quality management system, the cleaning of the production process, the splicing, the injection molding and other assembly options continue to automate the enterprise, including Large glass enterprises such as CSG and Yaohua and door and window curtain wall engineering company with glass deep processing production line, the quality control of another type of enterprise is not perfect, the equipment can only maintain simple intermittent production, even manual work, such enterprises nationwide There are many places in the northeast and the surrounding areas of Beijing, including glass decoration sites that can be used to bond hollow glass for sale. Automated equipment for mass production of insulating glass.
Great attention is paid to raw material sealants, mostly supplied or imported by specialized manufacturing companies. The supplier is required to provide a quality inspection report for the sealant batch product. Especially for the insulating glass used for curtain wall engineering, which has strict requirements on specifications and quality, it generally has standardized process control and product delivery inspection. In the latter category, the sealant market is more arbitrarily procured, and the suppliers are mostly from small rubber factories. Even some enterprises make rubber on their own, and the product quality is difficult to guarantee.
In order to cater to the demand of some enterprises for ultra-low unit price products, some small rubber factories use the simple equipment to produce sealant, and seize the market at low quality and low price. The sealant is on-site molding material, and does not pass the special instrument test specified by JC/T468 standard. , only from the appearance or inspection of the insulating glass after the handle. It is difficult to judge the quality of the quality. Some companies use this feature to try to reduce the effective ingredients in the formula. As long as the product is solidified, it can be cured on the glass. If you can't open it, you will dare to use it for the barrel. Taking polysulfide type sealant as an example, the current price of raw rubber is 35-40 yuan per kilogram. The content of raw rubber of high quality products is generally about 30%, and the selling price of products is more than 25 yuan/KG, but some enterprises are contracted in A large amount of oil and stone powder in the product will be effectively reduced to 15% or even 10%, and the product will be sold at an ultra-price of 15 yuan or even 10 yuan per kilogram. This rubber is more important and inelastic, not only resistant to bonding and It is difficult to guarantee the sealing performance. Some of them will be used to bond the hollow glass and will see out the “black water†on the inner surface. These sealants are not tested. The inspection report provided to the customer is not from the sealant product inspection agency, but mostly early. The result of the entrusted inspection from the insulating glass test facility. The proof of quality is independent of the factory batch sealant.
Problems with insulating glass
The quality control of insulating glass for public building glass curtain wall is relatively reliable. In order to realize the design of thermal parameters according to the building energy-saving standards, most engineering companies contracting curtain wall structures use high-quality energy-saving glass structure. The inner spacing of insulating glass is 12mm. Above, LOW-E glass, laminated glass or a dual-channel composite structure is used. The hollow glass was subjected to batch acceptance before the structural sealant was assembled. However, in some cases, when the safety is guaranteed, the durability of the insulating glass seal is often neglected. The insulating glass bonded by the silicone sealant is used for the framed or semi-concealed glass curtain wall, and the high moisture permeability of the glue will be The water content in the enclosed space is prematurely saturated, causing condensation inside the glass, LOW-E film to fall off, light transmission and heat insulation capacity to decrease, water will accumulate when the development is serious, and the alkaline salt of the desiccant dissolves and corrodes the metal frame to cause the product. Structural disintegration affects building safety and product life.
What is more worthy of attention is the insulating glass for ordinary windows. Some construction contractors pay a heavy weight and light quality, providing a market for the inflow of inferior and low-cost insulating glass. For example, in some buildings in the northeast and cold regions, the interior of the insulating glass is condensed, frosted or even accumulated, so that the owner or the occupant issues “cancel the hollow glassâ€. “Insulating glass is not as good as the double-layered building market, but the temperature difference is not as good. The northeast region is prominent, but the sealing failure of the insulating glass causes the dew point (regulated to -40 degrees) to rise or even condense, indicating that the thermal performance of the product is degraded or the function has been lost, and must be replaced. Continued use not only increases the energy cost of the owner, but also Will bring higher maintenance costs.
The national standard GB11944 "Insulating Glass" stipulates that the insulating glass sealing glue should conform to the industry standard JC/T486 "Elastic Sealant for Insulating Glass", which have different application scopes. However, some people mistakenly thought during the implementation. Insulating glass conforming to GB11944, the sealant for its manufacture is also a qualified product, and even the inspection report is used as the main quality proof for the delivery of the sealant. In the world, some inferior sealant bonded assembly of insulating glass, can pass the GB11944 factory inspection items (appearance, size and dew point), it is difficult to meet the type test of insulating glass products (high and low temperature performance, ultraviolet fog, climate durability) Etc.), but the insulating glass that cannot be made with JC/T486's sealant must meet the GB11944 standard.
Therefore, it is required that the insulating glass production enterprises correctly understand the standards, increase the implementation of standards, strictly control the quality of the sealant, and seriously treat the supplier to eliminate the inferior sealant. The construction engineering unit should review the batch of the insulating glass products. Certificate, at the same time check the assembly sealant in accordance with the JC/T486 inspection report. Some enterprises regard the report of entrusted inspection of insulating glass products as the qualified basis of sealant, and even used as the quality certificate of the rubber factory. In fact, the entrusted inspection is only responsible for the sample, so the qualification does not indicate the production of all the batch products of the entrusting unit. All are qualified, and it is not proved that the production quality of the sealant factory is qualified, let alone individual companies are not authentic.
Strengthening market supervision and promoting quality demonstration
In order to ensure the healthy development of the construction industry, to stop unfair competition, and to curb the proliferation of inferior and low-priced products, the quality certification of products should be promoted in accordance with the provisions of the Product Quality Law. Encourage quality and reputation-honoring enterprises to pass the nationally recognized quality certification body audit and obtain national certification qualifications. Construction enterprises should give priority to the use of sealant with quality certification mark and insulating glass manufactured by it. It is recommended that the state strengthen the quality supervision and inspection of insulating glass products, and conduct conformity inspection on key raw material sealants, and arrange quality inspection and inspection of special products for insulating glass sealants.
In addition, since the insulating glass is a product, as with safety glass and other products, there should be a product mark that does not fall off, indicating the manufacturer's name and the qualified code. It is recommended that the purchased product be inspected at the time of acceptance, and it is recommended to adhere to the structure with reference to the glass curtain wall. The management mode of the silicone structural sealant for assembly requires the supplier to provide a sealant qualification inspection report that is synchronized with the batch of insulating glass products, thereby effectively preventing the installation of the wall without quality assurance.
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