Tag Archives: outdoor linear lighting

As energy-efficient insulating glass products in China are becoming more widely and rapidly into people’s daily lives. But as the market competition, to gain the market share and lower sales price, but without causing margins were compressed, a result, many manufacturers use relatively inexpensive mineral oil as plasticizer sealant. At the same time, some manufacturers of insulating glass windows and doors do not understand the mineral oil companies because of the dangers of the use of hollow glass inexpensive glass, plastic, rubber and other weather sealant instead of insulating glass sealant use or use with mineral oil prices have low glass glue framed insulating glass installed on the building. Thus, in recent years, there have been mixed on the market of mineral oil insulating glass sealant and glass glue – the former directly as heretics of insulating glass and insulating glass sealant butyl rubber in direct contact within the Road, which is directly used instead of hollow glass sealant used or installed in the insulating glass and insulating glass outer frame when the sealant through direct contact point. Over time, the use of mineral oil-containing insulating glass construction using insulating glass sealant produced a series of serious quality problems: penetration into the mineral oil inside the inner channel butyl rubber, butyl rubber dissolved in the formula base material, butyl rubber is dissolved in mineral oil to soften and flow into the spacing layer of insulating glass, hollow glass, a large number of leaks, leak, and phenomena such as fog, so that shorten the life of insulating glass. As the mineral oil penetration to the inner butyl rubber in the road will take time, resulting in the insulating glass made at the time unable to see its quality, often hollow glass on the wall using only a few months after the emergence of large quantities D dissolve and flow into the base rubber insulating glass spacers, the quality problems occur with a lag, so I think that the quality control of insulating glass to be based on prevention – the use of glass, insulating glass sealant, or by detecting them with plastic before The use of butyl rubber is compatible, selected from qualified glass, insulating glass sealant or adhesive is very important and necessary.
A compatibility theory
1.1 heretics elastomer insulating glass sealant is mineral oil swelling theory
Outer insulating glass sealant is a thermoset elastomer, elastomer with flex – which is very important to seal abundance of applications – due to its molecular chains of about 10% of the gap – the “free volume”, however, kinds of internal voids also brought a number of other negative characteristics: liquid molecules into the sealant provides a physical way. Any kind of elastic body can not completely withstand the contact with the liquid caused by chemical or physical effects. Different elastomers different degrees of resistance to erosion, the elastic body into the liquid sealant compatibility with different sizes. If the elastomeric sealant to absorb a lot of liquid, due to the presence of crosslinks, elastomeric sealant can only produce swelling, but when the elastomer sealant deformation is constant, the stress will be as direct or indirect contact with the liquid time prolonged significantly reduced. This phenomenon is very detrimental in the sealed application, because the sealing material need to maintain a certain sealing force to prevent seal failure.

outdoor linear lighting

Elastomer sealant for liquid absorption consists of two physical processes ① dissolved in the liquid surface sealant (absorption): When the liquid come into contact with the sealant, the sealant surface is rapidly absorbed, its concentration and then quickly reached equilibrium concentration ② by diffusion into the liquid sealant inside.
Whether a particular sealant can absorb large amounts of low viscosity of the liquid depends on thermodynamic factors, the liquid mixed with the polymer, mixing free energy is:
△ G = △ H-T △ S (1)
Where: △ G – free energy of mixing, J
△ H – heat of mixing, J
△ S – mixing entropy, J / (kg · K)
T – absolute temperature, K
If the free energy △ G ≤ 0 ie △ H ≤ T △ S, indicate a driving force, the liquid spontaneously dissolved in the elastomer surface (absorption). Two materials are mixed, the material from the orderly development of the disorder, so mixing entropy △ S is generally positive. Exothermic dissolution process with (△ H <0), no heat (△ H = 0) or endothermic (△ H> 0) case. △ H large extent by the liquid and polymer solubility parameters d effects. According to Hildebrand theory:
△ H ≌ n1f2V1 (d1-d2) 2 (2)
Where, n1 – mole percent of solvent;
f2 – the volume fraction of solute;
d1, d2 – solvent, solute solubility parameters.
Seen from the above equation, because △ H and (d1-d2) 2 is proportional to the solubility parameter provides an approximate method of seeking △ H. Only when d meet specific conditions, △ H ≤ T △ S, for example, elastomers and solvents difference in the value of d 2.05-3.1Mpa1 / 2 between, will produce significant swelling. If the liquid is a medium-viscosity oil, d the maximum difference reduced to 1.64MPa1 / 2. Practical applications, in order to avoid thermosetting insulating glass sealant swelling, usually very different d values ??and liquid sealant system access, or improve flexibility in the structure, such as the crosslinking density, improve sealant Tg (equivalent to low free volume), high filler content in order to reduce the T △ S d value similar to offset the impact of the sealant surface to absorb the solution equilibrium concentration greatly reduced.

led linear light

Liquid sealant into the internal rate controlled by diffusion. In diffusion, a single liquid molecules “jump” transition to the neighboring free volume in the gap, this gap is caused by the kinetic energy of random thermal motion of the instantaneous sealant formed. At this point, is to promote the spread of thermodynamics of liquid sealant in trying to balance the chemical potential (ie concentration) provided. Migration rate in line with the liquid diffusion Fick law of diffusion. Fick law of diffusion in the solution of the appropriate boundary conditions is expressed as:
Mt / M ￥ = 2 / h (Dt / p) 1 / 2 (3)
Where, Mt – t time to absorb the liquid specimen quality;
M ￥ – equilibrium swelling time to absorb the liquid specimen quality;
2h – specimen thickness;
D – diffusion coefficient;
t – time.
Penetration of the molecular diffusion coefficient D by the size of the negative impact that the greater penetration of molecules, the higher the viscosity, D value is smaller. Under normal pressure, the diffusion coefficient of sealant has nothing to do with the pressure. However, under high pressure, pressure, there is a significant impact. As the swelling rate controlled by diffusion, so the elastic resistance to swelling as well as the spread of the square of the thickness of the fluid viscosity increases, with the liquid infiltration time increases.
1.2 Thermoplastic Road within the insulating glass sealant butyl principle dissolved
Thermoplastic sealant for liquid absorption also includes two physical processes ① dissolved in the liquid sealant on the surface (absorption): When the liquid come into contact with the sealant, the sealant surface is rapidly absorbed, its concentration and then quickly reached equilibrium concentration ② by diffusion into the liquid sealant inside. However, because of its thermoplastic, there are no crosslinks, so once the infiltration of liquid sealant in insulating glass sealant is butyl base materials (polyisobutylene and butyl rubber) and solvent, butyl produce insulating glass sealant dissolution phenomenon. Mineral oil (also known as paraffin oil) is a colorless, odorless, transparent and non-polar liquid, which is extracted by the oil liquid hydrocarbon mixture with alkanes and cycloalkanes. Butyl rubber is a low degree of unsaturation of non-polar rubber, and polyisobutylene is highly saturated linear non-polar polymers. According to similar principles of polarity and solubility parameters similar to the principle of mineral oil on the butyl rubber and polyisobutylene with a strong solubility. With the use of mineral oil molecular weight (or viscosity) smaller, due to the greater diffusion coefficient D, is more likely to enter into mineral oil butyl sealant to insulating glass to make it appear more easily dissolved phenomenon.