Sealants in the manufacture of glass

Last 2-3 years have brought a sharp rise in the volume window production in Ukraine. Along with the growth of window production increases and production of glass, from the subject of elite demand windows moved into the category of mundane goods available to a wide range of consumers. However, many subtleties steklopaketnogo production remain in the shadows. We hope that this paper will be useful to both investors and technical manager - in the adoption of plans, and staff in the department of complete sets of window plants, and above all the end user. Well-known glass - is glass with two circuits sealing. In the future we will talk about this design. Each of the circuits perform their specific tasks. In forming the primary circuit is used butyl sealant applied on an aluminum or steel frame in the molten state. Basis of fusible butyl sealant. Temperature of about 110-120 degrees C (for different products from different manufacturers). For the application of butyl sealant used different types of butyl extruders. These machines are widely available on the market - different volumes, performance and price (10000-40000 euros). The main function of the primary circuit - ensuring integrity of the closed mezhstekolnogo space. Possessing excellent ogdeziey to glass, aluminum, steel, and also a good plastic properties under the action of butyl press fills all the micro-defects on the glass and distance by combining the design into a coherent whole. It must be noted that the operation of a sketch of glass is compulsory and one of the main technological operations in the assembly glass. Attempts to save on butyl extruder led to the emergence of various substityutov: butyl string, sticky tape or aluminum range with a pre-deposited layer of butyl. All these methods have limited use for several reasons: low productivity, high cost components (butyl cord, the distance from the pre-deposited layer of butyl), poor quality of the finished glass (tape). The main function of the second layer of containment - the tradition of double-glazed windows of the strength properties. It must be remembered that windows during the operation are subject to wind, thermal, vibration, and so forth influences. Secondary circuit, along with durability and elasticity should have to compensate for the above mentioned factors. Currently, the following types of secondary sealants: hotmelty, polyurethane, polysulfides (Thiokol); silicones. Hotmeltami sealing technologies were widely circulated in Europe in the 70's early 80-ies. Made on the basis hotmelty is a single component thermosetting compositions are reversibly softens under heat and solidifying in the cold), for example, behaves construction bitumen. Hotmelta obvious advantages - cheap, simple, machine design process, the possibility of re-use in the production process waste materials, a short time curing sealant (measured in minutes). For application hotmeltov used hotmelt extruder representing heated to 170-190 "with heated tank, from which the pipeline is fed by melt termoizoliruemomu hotmelta (5000-15000 euros). Hotmelty packages are available from 1,5 to 50 kilograms, intended for different machines. Main packing a 6-pound block of x x. However, thermosetting properties hotmelta lead to the following effect: when heated in the sun softening the sealant layer leads to a deterioration of mechanical properties of glass. Sometimes there is even a partial swelling hotmelta heated in the low double-glazed window. With a significant cooling of hotmelt hardens, loses elastic properties, gives the crack. Wind effect leads to the separation of glass from the plastic mass. In addition, moisture (condensation) freezes in the microcracks, the ice breaks these cracks, the cracks penetrate pollution. Repetition of the process leads to the destruction of the sealant (remember the forgotten piece of asphalt construction workers on the street). Ultimately, this negatively affects the quality of glass. Longevity of glass collected using hotmelta about twice yields glazed with other secondary sealants. Today the most widely used secondary sealants - are the two competing technologies by using two-component polyurethanes and polysulfides. Both types of sealants congeal in the process of mixing the two components, the reaction of polymerization. Both types have high durability and low rates of gaseous diffusion. Around the same time and pour sealants (2-3 hours prior freezing; about 24 hours, subject to the final correct ratio of components). And polyurethanes, and polysulfides are designed for high production. Standard packaging is a collection of drums: Part A-190 liters, a component of B - 20 liters. And then it's time to tell about the practical differences between the two types of sealants. Firstly, when we talk about the engine design process, we must remember that we are dealing with a variety of chemical point of view of products. It follows from this difference in the machines to work with these products. Despite the fact that the principles are the same machines (they cost in the range 15000-40000 euros), in designs using different materials, there are differences in different sites. It is unacceptable to use an extruder to Thiokol with polyurethane and vice versa. Decision with which the sealant work is necessary to take in advance. Chemical differences of products lead to different behavior of blends, with some change in the ratio of components A and B. The classic, the well-known mixing ratio of 1:10 (by volume) may for any reason to be disturbed. By the way it must be remembered that the ratio for the products from different manufacturers differ slightly. For polysulfide violation ratios of components A and B (of course within reasonable limits 1:9-1:11) leads to a change in reaction rate, or acceleration or deceleration of the process. But the result - a frozen composition will have good mechanical properties. With this flexibility, two-polysulfides are widely used in "manual" insulating glass - weighing and mixing the composition with the help of simple tools. Radically different picture for polyurethanes. Violation of the dosage leads to a change in the structure of the resulting copolymer (fragility, or the mixture will stiffen at all). This property of polyurethanes virtually eliminates the possibility of using it in the manual mode of production. Working with polyurethane involves high technological discipline in production, quality and constantly controlled equipment for mixing, increased attention to routine maintenance. Somewhat to the side to hold sealants based on silicone. Beginning of their application 70 of the last century. Then came the notion of structural glazing, structural glazing. Known as one component silicones, and two-component. Some see the windows with silicone, almost as a panacea, but it's not quite true. Like everything else in this world of silicone sealants have strengths and weaknesses. Knowing them, we are able to apply correctly, these sealants. By the strong points of silicone sealants may include the following: resistance to ultraviolet radiation, the highest durability of the sealant. Facades, built in the 70's, are now. However, silicones are: high cost, high rates of gaseous diffusion, in order to achieve the characteristics of a standard glass-based polysulfide we are forced to increase the layer of silicone, which leads to a significant appreciation of glass, long-term containment (particularly for single-component silicone). Complete sealing of 20-30 days. In addition, one-component silicones have limited depth of hardening, making it virtually impossible for a layer deeper than 1 cm Although there is nothing in the case of manufacturing structural glazing silicone sealants have no alternatives. The last decades of manufacturers of materials for sealing the glass attempts to develop alternative technologies in the manufacture of glass. Among them are the "svigl strip, then the firm Tremco, a joint project of Henkel and Lenhard. The idea is the desire to unite in a single product function sealing the package, moisture absorption, and the definition mezhstekolnoy thickness. At the present stage, these efforts should not be considered fully successful if we consider them in terms of impact on the market. The high cost of product and equipment for its use, linking consumers to a single manufacturer of transportation and storage of semi-finished products, in our opinion outweigh the convenience of using this integrated product. What conclusions can be drawn from the above written: For manufacturers of glass, knowing the strengths and weaknesses of the technology sealing glass, select the appropriate technology specific to your production, do not use sealants dubious quality and unknown producers. For consumers, glass - good enough to learn more about the production of your provider, after all, depends on the quality of your final product.