Characteristics and application of compound sealing strip in system doors and windows

At present, EPDM, which has excellent weather proof ability and physical properties, is the main sealing strip used by system doors and windows enterprises, accounting for more than 85%.

With the increasing demand of the market for the performance of system doors and windows, the single EPDM extruded sealing strip can not meet the market demand.Some sealing strip manufacturers have subdivided the use of sealing strips. According to different positions of sealing strips, EPDM rubber/sponge rubber composite, EPDM rubber/glass fiber composite, EPDM rubber/sponge rubber/glass fiber composite and sponge rubber surface with smooth coating are used to solve various sealing and heat insulation problems.

1.Characteristics and application of EPDM rubber and sponge rubber composite products

In order to provide better air tightness, water tightness and dust-proof effect, the sealing part of the sealing strip is replaced by foam rubber instead of EPDM rubber. At the same time, the EPDM rubber with high hardness and excellent physical properties is still used in the installation part to ensure the firm installation of the rubber strip, which is not easy to fall off after long-term use.

The advantages of sponge rubber are: under the action of low pressing force, it can produce large elastic deformation, and because of its soft texture, it can well fill the gap on the profile surface to achieve effective sealing. At the same time, windows are easier to open and close. The compression stress curves of sponge rubber and solid rubber are shown in Figure as follow. The compression set of sponge rubber is better than that of EPDM rubber, which means that the stress relaxation loss of sponge rubber is smaller in long-term compression sealing. The stress relaxation test of sponge rubber in compression mode was carried out, and the results were calculated by Arrhenius formula: under the condition of 47 ℃, it will take at least 30 years for its compression stress to lose 15%. 

2.In addition to the application on the opening, PEDM / sponge composite sealant strip is also applied to the isobaric adhesive strip in the system doors and windows, as shown in the figure below:

The thermal conductivity of EPDM tape is about 0.25W / (m · K), which is slightly larger than that of sponge rubber which is 0.1W / (m · K) .The U value of the window can be significantly reduced by replacing the EPDM rubber strip with sponge rubber.