Analysis of the standard material density of the external wall thermal insulation material is low, the flame retardant lacks the insulation wall and falls into the "crisis"

Is the standard for external wall thermal insulation materials widened or tightened? On April 6th, Chen Fuguang, consultant of the Standardization Technical Committee of the Wall Standard Roofing Materials Standards Committee of the National Standardization Administration Committee, said on the policy of "2012 China Real Estate Engineering Procurement and Fireproof Exterior Wall Insulation Materials Application Discussion and Purchasing Special Session", regardless of policy How to change, polystyrene board (EPS) and extruded board (XPS) and other materials in order to re-enter the insulation market, improve the performance of flame retardants and enhance insulation performance is a must.

The background of this situation is that on December 30 last year, the State Council issued the "Opinions of the State Council on Strengthening and Improving Fire Fighting Work". Subsequently, on February 10 this year, the Ministry of Housing and Urban-Rural Development issued the "Regulations on Implementation." The Notice of the State Council on Strengthening and Improving the Opinions on Fire Fighting Work requires all localities to strictly implement the relevant standards and regulations and strengthen the fire safety management of construction projects, which has been interpreted by the industry as “the policy restrictions on external wall insulation materials have been relaxed”.

Density determination coefficient

In Chen Fuguang's view, the key to improving the performance of insulation materials is to ensure the density of the product, "because the density of the insulation material is related to the thermal conductivity."

It is understood that in terms of product density, for domestic insulation materials such as EPS and XPS, the domestic standard is 18 kg/m3 to 22 kg/m3, while the foreign standard is the density of insulation products not less than 22 kg/cubic. Rice, most products have a density of more than 25 kg / m3.

Chen Fuguang introduced that because China's standards have low requirements on the density index of insulation products, developers did not think of this problem when purchasing, which led to a significant reduction in the insulation performance of wall insulation products used in construction.

Even more frightening is that low-density insulation boards of 10 kg/m3 to 12 kg/m3 are often found in the building materials market today. Chen Fuguang said that when he visited the Northeast, he found that there was a thermal insulation board with a density of 12 kg/m3 on the market, and the staff told him that the thermal conductivity was 0.04, and he took out a test report to prove his claim. Later, Chen Fuguang came to the inspection unit to understand how this data was derived. It is understood that the standard test method specifies a temperature of 25 ° C, and this test unit reduces the temperature to -10 ° C, so that the measured thermal conductivity is definitely low.

“Therefore, the standardization of the detection method is also very important. If the detection method is not standard, the data to be tested will have no basis, and the performance of the insulation material cannot be ensured.” Chen Fuguang emphasized.

Improve flame retardancy

Since EPS, XPS and other organic materials are relatively flammable, if used for wall insulation, flame retardant should be added to increase the oxygen index (high oxygen index means the material is not easy to burn, low oxygen index means the material is easy to burn, generally considered oxygen index <22 It is a flammable material with an oxygen index of 22 to 27 being a combustible material and an oxygen index of >27 being a flame retardant material.

It is understood that the United States has the strictest requirements for building fire safety. For building exterior insulation materials, the oxygen index of fire retardant is specified to be greater than 35%, and the oxygen index of products manufactured by enterprises is generally 36% to 38%; in addition, the standard of Germany It must be no less than 35%; the British standard is not less than 33%. The standard in China is not less than 30%.

“Even if the standard is lower than the foreign countries, most domestic products still do not meet the standard requirements, because they do not add or add a small amount of flame retardant.” Chen Fuguang said.

At present, the price of 1 ton of flame retardant is 250,000 to 260,000 yuan. The addition of flame retardant to organic insulation materials will inevitably increase the cost of the product. This is the root cause of many manufacturers not adding or adding flame retardants.

In addition, at present, most of the flame retardants in China are organic compounds, which emit strong black smoke when burned. The US products ignited a small amount of white smoke, and they went out in less than a second, and there was no ignition. It is understood that nitrogen or nitrogen compounds are widely used in developed countries.

“At present, I have not seen any domestic company to develop non-toxic and harmless flame retardants.” Chen Fuguang called at the meeting, “We should improve the fire performance by improving the performance of flame retardants, which is also to improve the building. The most effective measure for constructing system fire safety."