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Material Selection
May 22, 2018

I. material selection:

The performance and life of the sealed strip product depends on the selection of the material. According to the classification of chemical building materials in China, the main materials used for door and window seals are divided into thermoplastic elastomers and vulcanized rubber seals.

1. Thermoplastic elastomers (SJT)

The single blend modification material of PVC resin tube. PVC resin with high polymer modifier (generally use cross-linking type butadiene-acrylonitrile rubber or rubber type chlorinated polyethylene) modification and production of strip commonly referred to as blending PVC elastomer seals or modified PVC sealing strip. Because the material added polymer modifier, sealing strip of resilience, high and low temperature resistance are improved, and high strength, good ageing resistance, the basic physical properties can reach the standard of GB/T12002 or JG/T187, price moderate, currently use is common used in the manufacture of building doors and Windows sealing strip.

Some enterprises use the different quality, the composition of complex waste production sealing strip, and without modifying agent at the same time when blending excessive add filling material, becomes a highly filled PVC sealing strip, the strip intensity difference, low elasticity, easy to fracture. Some manufacturer of alternative plasticizer added aromatic oil or heavy oil, oil refining slag sealing strip products not only pungent odor, and the deformation shrinkage in the short term, or even fall off, lose doors and Windows sealed, so this kind of strip must be prohibited from use.

The dynamic vulcanized thermoplastic elastomer material (TPV) was used for the tri-propylene/polypropylene crosslinking. This is a kind of foreign already established standard, domestic also has industry standard new material, domestic and foreign building door window all have use. This kind of TPV material performance and vulcanized epdm, due to its good manufacturability, high rate of proportion of small, out of the window, do not contain heavy metals and halogen, is a kind of energy efficient and environmentally friendly new materials of high practical value. More than 4000 yuan /M2 above quality building starts to choose.

The modified elastomer material (TPE) was mixed with high polymerization resin. Biggest characteristic is without vulcanization process, and is made of thermoplastic plastic forming methods for processing, can greatly shorten the molding cycle, and waste also can be recycled and used again, section information and energy saving, is a very promising material, can be used as a substitute of vulcanized rubber. The modified PVC sealing strip has good compression and permanent deformation, and is considered by the national architecture association as an alternative to EPDM as the sealing strip and weathering strip for doors and Windows. Its performance is the same as that of TPV, but the ingredients used are different. At present, the selling price is slightly lower than TPV. For the customers, it belongs to the high-quality and inexpensive products, and improves the window level without raising the cost. With extremely high market promotion value, it has become the preferred material for manufacturing enterprises and export products.

2. Vulcanized rubber seals are mainly EPDM (EPDM) :

This kind of material is made of sealing strips with excellent aging properties, suitable for sealing and sealing of doors and Windows. It has once been the preferred material for sealing at home and abroad. However, the vulcanization type of vulcanization requires the production line to complete, the production cost is high, the price of EPDM raw glue is high, and the price of high grade EPDM sealing strip is high. The low price of products in the market, a large amount of calcium powder, waste materials, etc., poor quality.

EPDM products are lower than major ones, and contain heavy metals, including nitrosamines (carcinogens), which are banned in many countries. Moreover, the products cannot be recycled and are not conducive to environmental protection. For the current international promotion of green environmental protection, the market will be phased out gradually.

2. Check the test report:

No matter what kind of seal is used, it must have sufficient tensile strength, good elasticity and hardness, and its physical properties should meet the standards of gb12002-89 or JG/ t187-2006. When purchasing, we should check the manufacturer's inspection report, product qualification certificate, and sign the quality assurance agreement with the manufacturer. The standard PVC modified seal strips can last up to 15 to 20 years, and thermoplastic ternyl (TPV) seals can last up to 30 years.

3. Practical performance test:

1. Check whether the surface of the adhesive tape is smooth, free of impurities, no bubbles, no indentations, and the hands are sensitive and soft. High - filled soft PVC or EPDM seals have poor elasticity, rough surface and large deformation.

2. The hand should be properly stretched without breaking, and can be recovered quickly after bending. High fill soft PVC sealing strip strength difference, one fold break, one pull to break.

3. Smell of aromatics with nasal odor. Some PVC seals not only use the waste of different quality, but also overfill in the formula with fillings and low molecular weight of aromatic oil or complex oil refining oil residue heavy oil as plasticizer substitute. This product just factory smell is bigger, more over time, the composition of volatile, sealing strip soon hard brittle hair, make a strip contraction, become loose, fall off, cracking easily aging, lose the sealing function. As a result of aromatic oil or heavy oil migration can also cause the profile to turn yellow.

4. Practical inspection: the adhesive strip shall be inserted between the profile and the glass to check the rationality of the section shape and the suitability of the size. It is not easy to press into the tape, and the bigger the glass is, the better. If there are conditions, you can also find a professional third-party testing institution for water and air tightness test.

To sum up, the quality of adhesive strips can be directly identified from the appearance, strength, smell and combustion of the sealing strip.

Poor quality polyvinyl chloride (PVC) sealing strip surface roughness, large deformation, poor strength, a break. The nose has a smell of fantine. After the combustion is extinguished, the packing is very short.

High quality modified polyvinyl chloride (PVC) seal has fine surface, good brightness, high strength, good elasticity and no smell. When burning, the flame is yellow, and the root is green, with the smell of chlorine gas.

Vulcanized EPDM (EPDM) sealing strip strength, good elasticity, small deformation, surface brightness, than big (1.5), the combustion flame when the roots show blue, smoke-free, no sticky residue, after burning can't drawing.

TPV/TPE sealing strip of thermoplastic elastomer is superior to that of vulcanized ternene seal, which can float on water (0.90-0.95), with excellent elasticity and tensile properties, with various colors.

4. Improve the quality awareness of the seal strip.

From the market analysis of middle and window doors and Windows, the cost of sealing rubber strip accounts for only 0.1 to 0.5% of the Windows and doors. For the whole construction project, the cost is very small, but the role of the seal is not negligible. We have encountered some enterprise for high-grade villa doors and Windows appear serious quality problem, the owner is not in the found the doors and Windows in the rain, the survey found that belongs to the sealing strip contraction caused by, the result all the rework to replace the comer. The company saved small money but caused great economic loss and reputation loss.

So, we should develop enterprise, supervision unit, doors and Windows, sealing strip production enterprises, improve the understanding of window functions and the related seals, correctly handle the relationship between price and quality, for the production and use standard sealing strip space set aside a reasonable price.

Secondly, the relevant supervision and window enterprises should adhere to the standard audit according to the standards of purchasing and use of sealing bars, which shall not be used in any substandard low-price and low-quality seals, and the market of construction accessories shall be standardized. Relevant standards, such as "plastic door and window seal tape" (GB/ t12002-1989), "building doors and Windows sealing tape" (JG/ t187-2006).

Third, sealing strip production enterprises should constantly improve the social responsibility, eliminate inferior seals, actively promote technology innovation, to build their own brands, do not participate in the low price competition, promote the level of industry continue to improve