NEWS

In the past use process, plastic doors and windows were affected by low-performance and poor-quality sealing materials, and their quality and service life were greatly affected. There have been many quality problems, which have seriously damaged the reputation of the business.Especially used in doors and windows of construction projects, light ones harden and become brittle, losing elasticity and sealing function, while heavy ones become sticky and “oil seepage”. While losing the function of use, they pollute the doors and windows and affect the aesthetics of the doors and windows.

The occurrence of this phenomenon can be attributed to the fact that while enterprises improve the grade and performance of plastic doors and windows, they ignore the introduction and development of door and window accessories, resulting in the development of sealing materials far behind the development of plastic doors and windows.It is gratifying that high-end and high-quality door and window accessories, especially door and window sealing materials, are being accepted by everyone and are gradually entering the door and window market.

Material status of plastic door and window sealing strips

At present, the main sealing strip materials used abroad are nitrile rubber, EPDM rubber (EPDM), thermoplastic elastomer (TPE), polyurethane elastomer (P), silicone rubber, etc., and the use rate of EPDM rubber with excellent aging resistance is higher, reaching more than 60%.

Analysis of the development status of plastic door and window sealing materials in China

In recent years, in the domestic market of door and window sealing materials, the share of sealing strips made of plasticized polyvinyl chloride has reached more than 90%, while the market share of modified high-polymerized polyvinyl chloride and thermoplastic elastomer sealing strips recommended by relevant departments in the industry is extremely low, most of them are concentrated in the surrounding areas of Beijing.

EPDM rubber material was developed in our country by the Beijing Institute of Chemical Industry in the 1960s, but its application and development in doors and windows was only put on the agenda in the mid-1990s, and it was developed by the Rubber and Plastic products Factory of the Capital Aerospace Machinery Company in 2000. It passed the acceptance of relevant experts from the Ministry of Construction at the end of the same year. It is currently in the mass production stage, but only some domestic high-end door and window manufacturers are in use.

The market price of domestic EPDM rubber sealing strips is about 40% lower than that of similar foreign products, but the development is still slow. The reason is that the majority of users have not yet realized that the sealing strips account for a small proportion of the total cost of door and window manufacturing. Cost savings are only considered, and the comprehensive benefits brought about by the use of high-priced and high-quality sealing materials are not considered.

Sealing strip cross-section design and mold making process status

Due to the late development of domestic plastic door and window sealing strips, the initial cross-sectional shape is relatively simple and is limited to the “K”-shaped strips used for glass pressure strip sealing, the large spoon strips used for window frame (fan) sealing, and the small “0” strips used for gauze fans. The variety is relatively single.On the contrary, with the development of plastic doors and windows, the production of foreign sealing strips has reached serialization and scale. The design of the cross-section of each product meets the requirements of the relevant use functions, and the cooperation with the corresponding profiles is almost perfect.

The report shows that in recent years, with the introduction of foreign door and window manufacturing technology, the cross-sectional shape and variety of domestic sealing strips have also undergone great changes, but due to the backwardness of domestic mold making technology and the insufficient attention paid by domestic peers to the sealing material as one of the door and window accessories, the resulting products are close to the designed shape in terms of shape, but there are still some defects in the use function, such as the large gap between the mating parts, the amount of compression and lap of the finished product does not meet the relevant requirements, etc., so that some quality problems will inevitably arise during use.In addition to being affected by the above-mentioned factors, the occurrence of this phenomenon is also affected to a greater extent by the raw materials used, such as the processability and expansion rate of the materials.

EPDM rubber is a kind of sealing material with extremely excellent overall performance. Not only does it have excellent physical properties, but its processing properties are very good and the expansion coefficient is very small. The sealing strip made of this material is almost not much different from the design requirements. This is also an important reason why EPDM rubber has developed rapidly in recent years.