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Necessary knowledge about heat insulation strips - part 1

Time : 2022-10-14 Hits : 2

At present, there are three kinds of bridge cutoff aluminum alloy door and window insulation strips, one of which uses PVC (polyvinyl chloride) as raw material, one of which uses PU (polyurethane) as raw material, and the other of which uses PA (polyamide, commonly known as nylon) as raw material. PVC and PA insulation strips are both extrusion processes, and PU adhesive strips are injection processes. This article will mainly introduce the relevant knowledge of PA insulation strip.

Comparison of the performance of the PA heat insulation strip and PVC heat insulation strip

1. The main raw materials of PA heat insulation strip are PA66 plus 25% glass fiber, and the main raw materials of PVC heat insulation strip are PVC resin powder plus 25% calcium carbonate. Compared with PVC heat insulation strip, PA heat insulation strip has the following advantages:

(1) High tensile strength

PA heat insulation strip:>=126N/mm PVC heat insulation strip: about 70N/mm


(2) High thermal deformation temperature

PA insulation strip: 240 ℃ PVC insulation strip: 90 ℃

(3) Durable, PVC insulation strips are easy to age

(4) Good self extinguishing performance

2. How to distinguish between PA insulation strip and PVC insulation strip

(1) The appearance of the PA heat insulation strip is not as smooth as that of the PVC heat insulation strip

(2) It only takes one or two times to break the PA heat insulation strip by hand, while the PVC heat insulation strip takes more than ten times

(3) There is a crisp sound when the PA heat insulation strip breaks, and the fracture occurs after breaking

No deformation at the position can be docked and restored; After the PVC heat insulation strip is broken, the fracture is white and deformed, and can not be docked and restored.

(4) Equivalent specifications and models, such as I-14.8, PA heat insulation strip in metric weight

45.1g, PVC insulation strip weighs 57g

National standard for PA heat insulation strip

In August 2008, the National Standardization Committee held a meeting to formulate the 'National Standard for Thermal Insulation Strips' in our company. Our company participated in the formulation of the national standard GB/T23615.1 Auxiliary Materials for Aluminum Alloy Building Profiles Part 1: Polyamide Thermal Insulation Strip. 1. Test spline requirements

The samples must be dried, and the moisture content is less than 0.2% (weight percentage) or dried in a 140 ℃± 2 ℃ ordinary drying oven for 6 hours before completing all tests within one hour 2. Test environment room temperature: 23 ℃± 2 ℃ 3. Characteristic values of several main indicators (1)

Calculation formula of characteristic value: characteristic value=mean value -2.02 * S variance S=[mean value − T1 2]/[(number of samples (n) − 1] 2

Transverse tensile strength T1=maximum transverse tensile resistance/sample length

Average value=T1/number of samples n

(2) Transverse and longitudinal tensile strength

Transverse tensile strength>=70Mpa=126N/mm/1.8mm Longitudinal tensile strength>=80Mpa=144N/mm/1.8mm Note: As a structural member in the bridge cutoff aluminum alloy door and window system, the thermal insulation strip plays an important role in connecting two aluminum alloy profiles in physical properties. Aluminum alloy doors and windows with substandard heat insulation strips will break, leading to the malignant accident of window falling.

(3) Thermal deformation temperature

Thermal deformation temperature>=240 ℃

Note: The internationally accepted process of using heat insulation strips is to wear them first

Spraying after the strip. As the temperature of the oven during spraying is 200 ℃, if the thermal deformation temperature fails to meet the requirements, the heat insulation strip will bubble or deform on the surface, resulting in scrap of the profile. If the temperature of the oven is too high during spraying, the heat insulation strip will also show bubbles or deformation.

(4) Impact strength

Impact strength (without notch)>=35KJ/m ² Or continuous crack note: when the aluminum profile factory penetrates the heat insulation strip into the profile, such as punching

If the blow is not enough, the heat insulation strip will crack, resulting in scrap of profiles. If the pressure setting is not reasonable (more than 300N) when the profile is threaded in the factory, the insulation strip will also crack. (5) Stress cracking performance After the stress cracking test (shaft pin) is completed, all samples shall be free of cracks. Note: If the stress cracking performance is not up to the standard, it will lead to the same consequences as (4).

(6) Transverse tensile strength at high temperature and low temperature

Detection environment: high and low temperature box

High temperature: 90 ℃± 2 ℃ Low temperature: - 30 ℃± 2 ℃

High temperature transverse tensile strength>=42Mpa Low temperature transverse tensile strength>=70Mpa

Note: The high and low temperature experiments simulate the heat insulation strips at high temperature and low temperature

Failure to meet the standard when using in a warm environment will lead to breakage of the insulation strip.

(7) Glass fiber content

Glass fiber content: 25% ± 2.5%

Note: glass fiber plays a reinforcing role, for example, too few glass fibers will affect the strength of the insulation strip; If the glass fiber exceeds the standard, the impact strength of the insulation strip will be reduced and the stress cracking performance will be affected.

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