In recent years, the rock wool industry development has ups and downs, on the one hand, rock wool production rapidly promote new capacity reaches ten thousand tons, 100, on the other hand by the influence of the policy, the exterior insulation with rock wool products demand is reduced, cause the market supply. In this situation, the external wall thermal insulation in the condition of the rock wool products quality is more important.

 

For monitoring and maintaining the exterior insulation with rock wool, the quality of the product and order to further promote rock wool and healthy development in the field of building energy efficiency, national glass fiber products quality supervision and inspection center, according to the requirements of rock wool industry parties succeed in the last year, on the basis of rock wool products pattern inspection in March of this year and carried out the external wall thermal insulation with rock wool product sampling pattern inspection activities. Voluntary application by the enterprise to participate in the activity, inspection of products for the rock wool board and rock wool, inspection according to the standard of GB/T 25975-25975 "building exterior insulation used rock wool products, inspection items, a total of 16, including all routine inspection items, to ensure that the representation of the test results, and check sample inspection personnel unified by the center to the enterprise production site randomly. The scope of the inspection, involving eight provinces and three municipalities directly under the central government a total of 22 companies across the country 35 batches of products, including 34 batches of qualified.

 

Compared with 2013, the overall situation of rock wool enterprises no big change, the current domestic product quality is better or produce larger companies took part in the test.

 

To participate in the activities of the test of rock wool enterprise, its production line both lines to domestic or imported, their production scale and technology level are leading in the industry, they represent the exterior insulation used in our country rock wool quality level. Can think, through the enterprise type test, is a production of qualified exterior insulation with rock wool products.

 

According to the rules, the only announced the list of qualified enterprises. In addition, the industry there are quite a number of enterprises did not participate in the inspection, these firms have a plenty of equipment level and production technology don't have a production capacity of building exterior insulation with rock wool, claimed that only in the production of industrial heat preservation with slag cotton or other requirements is not high rock mineral wool products, also have a plenty of product quality control is lax, can not meet the standard requirements, no faith about whether can pass the sampling inspection.

 

Test result analysis

 

1. The density and size

 

Density and size of the rock wool products the most basic and important technical parameters. In the product of the production and application practice, the density is closely related to product price and performance, and size directly affects the construction effect, therefore, manufacturers and users are used to to nominal density and size of the specifications of the products.

 

Density control is closely related to the production equipment and process control. The density of products directly affects the thermal resistance, tensile strength and compression strength, such as performance, therefore in the process of production need to monitor product density at any time, in order to timely adjust equipment parameters, guarantee the performance of the product.

 

This test, rock wool with nominal density in general (100 ~ 120 kg/m3), within the scope of the nominal density of rock wool board is in commonly (120 ~ 180 kg/m3). Actual testing product density and the nominal density deviation statistical results are shown in table 2.

 

General rock wool products density deviation requirements within 15% or 10%, while data table 2 shows that the exterior insulation with deviation in 5% less than the density of rock wool products accounted for 85.7%, this part illustrates the enterprise to control the density of the well.

 

Exterior insulation with rock wool products, the size of the consistency is very important. Uneven thickness, metope, length or width, gap is big, easy create joining together influence the heat preservation effect. In the national standard for rock wool board and the size of the cotton belt deviation has clear rules allowed.

 

The sampling size variation pattern examination in the qualified range, size the percent of pass is up to 100%, it can be seen that rock wool production enterprises has been well mastered the size control process.

 

2. The average fiber diameter

 

Fiber diameter is characterization parameters of the fiber thickness, the diameter of the fiber is fine, the product feel more soft, construction performance of the product and heat conduction performance, the better. Standard requires fiber mean diameter is not more than 7.0 micron. The inspection result of this year, the average fiber diameter less than 7.0 micrometers, which is less than 5.0 microns (48.5%), 70% in 2013 to reduce by 70%. Fiber is fine, will reduce output corresponding, this shows that there are some enterprises in the process of production for production cost reduction, relax the requirements of fiber diameter, need special attention.

 

3. The content of slag ball

 

Slag ball means rock wool products of central fibrous solid particles. The standard diameter greater than 0.25 mm particles called slag ball. Slag content, the greater the ball fiber rate is lower, each performance is poorer, rock wool products. Therefore in the process of production to try to control the content of slag ball as small as possible.

 

Specified in the standard content of slag ball shall not exceed 10%. The test of the slag ball content are less than 10%, and less than 5% 78%, increase than last year's 70% to a certain extent, it can be seen that, along with our country rock wool production line equipment and technology level enhancement, fiber forming rate is higher and higher, the content of slag ball more and more low, which was beneficial to the improvement of the rock wool production enterprises, but also reflects the enterprise's production level is rising.

 

4. The right Angle deviation

 

Right Angle deviation: refers to the products of two adjacent edge to the degree of deviation Angle, deviation is too big, can make the surface flat-fell seam is too large, affect the heat preservation effect. The main cause of right Angle deviation is horizontal flying saw frame speed conveyor speed not synchronous with the roller group, reflecting the rock wool production line equipment manufacturing and control level.

 

The inspection all the right Angle deviation of the sample are less than 5 mm/m, meet the standard requirements, which accounted for 56%, within 3 mm/m (3 ~ 5) mm/m accounted for 44%, 58% and 42% of the basic flat with last year.

 

5. Flatness deviation

 

Flatness deviation refers to the two rock wool products surface uneven arching, flatness deviation is too big, not only affect the construction, but will have a negative impact for the heat preservation effect. The test sample roughness deviation measurement value is 0.0 mm, without warping phenomenon, have good flatness.

 

6. Dimensional stability

 

Dimension stability of the rock wool products refers to the place after a period of time under certain temperature conditions, rock wool product length, width and thickness direction perpendicular three-dimensional irreversible size changes. The inspection, after (70 + 2) ℃, 48 hours after treatment, all 35 samples, dimensional stability in the rate of change of length, width and thickness direction is the same as last year's results, are all 0.0%, it also illustrates the for exterior insulation with rock wool almost won't produce deformation under normal temperature. National standard of flatness and dimension stability of rock wool products to certain requirements, main is to prevent because of heat preservation material surface uneven or as a result of the natural temperature variations, rock wool product size change, building external wall insulation wall caused by bulging deformation, affect the quality of the building thermal insulation engineering.

 

Of the size of the products produced or decrease, is caused by product internal stress. Rock wool itself is inorganic silicate materials, relative to other material, its thermal expansion coefficient is small. Rock wool products, on the other hand, is the flexible fiber materials, energy absorption capability is strong, won't produce stress concentration. So the deformation of rock wool products surface roughness deviation and size of possibility is very small, the stability of the external wall thermal insulation.

 

7. Tensile strength perpendicular to the surface

 

Also known as the tensile strength between the layers, guarantee the safety of external thermal insulation system is important to performance. Specified in the standard rock wool with tensile strength should be no less than 80 kPa; Three is defined for rock wool board tensile strength grade, respectively is:

 

TR7.5 tensile strength is not less than 7.5 kPa

 

TR10 tensile strength is not less than 10 kpa

 

TR15 tensile strength is not less than 15 kpa

 

The sampling pattern examination in 35 samples with one rock wool board is unqualified.

 

To improve the tensile strength between the layers of rock wool products, the key is pleating technique adopted in the process of production. So-called pleating, multi-layer fold laying cotton blanket to longitudinal compression, wrinkle the laminated arrangement fiber layer twists and turns, the change of the fiber arrangement, form a three-dimensional structure. Pleating technique effectively changed the product of the application of the arrangement of the fiber layer, thus significantly improve the tensile strength between the layers of the products.

 

Analyses the reason of the unqualified, mainly products pleating incomplete, look from the thickness direction, most of the fiber pleating, good connection between the fibers together, and away from the product surface is about 1 cm thick fiber pleating, fiber base layer structure, resulting in a decline in the integrated intensity of the product.

 

8. The coefficient of thermal conductivity

 

Coefficient of thermal conductivity is one of the important parameters of the measured material heat preservation performance. It refers to the steady heat transfer conditions, the material thickness is 1 m, two surface temperature difference of 1 ℃, within an hour, by 1 square meter area of heat transfer, the unit for W/(m.K), usually expressed in symbol lambda.

 

Coefficient of thermal conductivity and density, fiber diameter, slag ball is closely related to the content and products within the fiber arrangement way. For a certain density of rock wool products, fiber diameter, the more fine, slag ball content is less, the lower the coefficient of thermal conductivity. Pleating products than pleating higher coefficient of thermal conductivity of the product. Coefficient of thermal conductivity and the tensile strength between the layers, there are some contradictions between the two performance to improve interlaminar strength, to improve the pleating than, add more vertical fiber, but the vertical direction of fiber is much, will increase the conduction of heat, thermal conductivity increases, for manufacturing enterprises to do the balance between the two is very important. The coefficient of thermal conductivity of the sampling inspection, all samples are qualified.

 

9. The compression strength

 

The compression strength of rock wool products, is the point at which the compression failure load and the ratio of area. If appear before compression to the thickness of the 10% maximum load, maximum load to failure load, maximum load, if not the compressed to 10% when the load of the thickness of the breaking load.

 

The 35 samples to test, compression strength of all qualified. Rock wool board and the compression strength of rock wool with a maximum 89.1 kPa and 241 kPa, have improved over the past year, especially rock cotton belt, increase the size of the largest. Up to 136%.

 

Because the rock wool board and rock wool fiber layer structure is different, its performance in compression is not the same. Rock wool with the compression, the deformation is small, load increase rapidly, there is an obvious limit failure load, then the bearing capacity. Compression of rock wool board, deformation, load with the increase of deformation is bigger and bigger, no obvious damage point.

 

The water absorbing capacity

 

Water quantity is the characterization of material parameters of water absorption capacity. And rock wool, people pay close attention to in the application of two main surface water sample in the standard requirement, the sample surface under 10 mm away from the surface of the water, soaking time for 24 hours, water quantity is not more than 1.0 kg/m2.

 

Water quantity is the rock wool products meet the ability of water intake of water, as building insulation materials inhaled more water, will not only make the system of the heat preservation effect will be greatly decreased, but also affects the durability of the system. From the results of inspection: all 35 samples, 27 short-term water quantity is 0.1 kg/m2, four short-term water quantity is 0.2 kg/m2, four short-term water quantity is 0.3 kg/m2. Overall water quantity is small, all within the 0.5 kg/m2, and most of them are 0.1 kg/m2, this also reflects the current production technology of waterproof processing, all the better product basic not bibulous, conducive to the application of external thermal insulation.

 

11. Hydrophobic rate

 

Hydrophobic ratio is an indicator reflecting the material resistance to water penetration, is to use a certain flow of water to spray sample after 1 h, not flooded part of the percentage by volume of the sample.

 

The sampling type inspection hydrophobic rate are unqualified, the smallest is 98.8%, maximum of 99.9%. All 35 samples, in addition to a rock wool with hydrophobic rate was 98.8%, the rest are all over 99.4%, from the test in the process of observation, spray water on the sample all can have a lotus leaf effect soon run out, so that products have very good hydrophobic effect, is helpful to keep good heat preservation effect and durability.

 

12. Quality moisture absorption rate

 

Quality reflects the material moisture absorption rate in wet's capacity to absorb water vapor in the air. Quality moisture absorption rate, the greater the material quality in damp environment change, the greater the coefficient of thermal conductivity of materials, reduce the heat preservation effect, but also not conducive to the stability of the system.

 

The inspection, all 35 samples of qualified, 13 samples quality moisture absorption rate is 0.0% ~ 0.1%, 21 samples quality moisture absorption rate is 0.2% ~ 0.4%, and 1 as a sample the quality of the moisture absorption rate of 1.0%.

 

13. Acidity coefficient

 

Acidity coefficient is rock wool the ratio of the chemical composition of the acidic oxides and alkaline oxide.

 

Generally believe high acidity coefficient, rock wool chemical stability and good durability, but high acidity coefficient, can lead to production of melting temperature will increase, fiber forming trapped d, fiber diameter increasing and energy consumption, etc. Standard acidity coefficient should not be less than 1.6.

 

The inspection of acidity coefficient all qualified products.

 

Compared with last year, the product acidity coefficient is higher and higher, only 2 as a sample is less than 1.8, which accounted for 5.7% of the sampling, the remaining 94.3% of the products is greater than or equal to 1.8, the largest of which is 2.5.

 

14. The combustion performance

 

As the density of rock wool is inorganic heat preservation material, relatively large, and less organic matter, these factors determine the rock wool products has great advantage on the combustion performance and the sampling all the sample combustion performance by noncombustible experiment.

 

The quality of analysis

 

Compare two years all inspection results of the project, rock wool products found in density deviation and average fiber diameter, tensile strength, compression strength and acidity coefficient has the obvious change, main show is as follows:

 

1. The density deviation

 

This year, compared with last year, rock wool products density deviation in 5% 85.7%, 22.1% higher than last year's 63.6%, this shows fully convincingly that enterprise has significantly increased in density control level.

 

2. The average fiber diameter

 

This year the average fiber diameter less than 5 microns (51.4%), and last year accounted for 70%, average diameter coarsens more products, this is not conducive to the performance of the products, need attention, and attention to all enterprises.

 

3. The tensile strength

 

Tensile strength project last year have four product is less than 7.5 kPa, percent of pass is 12.1%, this year only one is less than 7.5 kPa rock wool products, fraction defective is 2.8%, fraction defective is greatly reduced.

 

In addition this year maximum tensile strength of rock wool board and rock wool belt were 24.1 kPa and 426 kPa, respectively 26.5 kPa last year and 400 kPa. Can be seen from the data at present our country enterprise produce the tensile strength of rock wool board at the highest level in more than 20 kpa, the tensile strength of rock wool with the highest level in more than four hundred kpa.

 

4. The compression strength

 

Compression strength projects last year, has two products is less than 40 kpa, fraction defective is 6.1%, this year all qualified 35 samples of this project, and rock wool with the maximum compression strength up to 241 kpa, higher than the maximum compression strength last year 108 kpa to 133 kpa, and product tensile strength reached 426 kpa, realized the qualitative leap.

 

5. Acidity coefficient

 

Product acidity coefficient has the obvious enhancement, acidity coefficient is less than 1.8 of 5.7% this year, 12.1% of last year, and the acidity coefficient reaches 2.5 biggest.

 

conclusion

 

Building exterior insulation with rock wool products industry sampling pattern examination has for two years in a row, this activity by the enterprise's strong support over the past two years, building energy efficiency design, construction and application of departments at all levels of leaders and experts also very concerned about. How to play a good fire rock wool products characteristics and good performance of heat preservation, promotion of rock wool application in building energy efficiency, the quality of the rock wool products become one of the focuses of the from all walks of life. Compared with last year, the quality standard of the rock wool products have obvious improve, especially in intensity, some key technical indicators, such as acidity coefficient have made progress, some products reached the international advanced level. Each year for the fact that the sampling of the type of inspection of the whole industry is not only a comprehensive rock wool product quality inspection, and quality control of rock wool production enterprises an effective supervision ability and level, through such activities can make enterprises found that the problem, find the gap, to improve technology, improve product quality. Sampling pattern examination result can objectively reflect the quality level, at present our country rock wool products for the government to make industry development planning and provides the technical support for the user to select products. The sampling pattern examination qualified enterprises, with the production of building exterior insulation with the ability of rock wool products, represents China's current exterior insulation yanmian products quality level.

 

Survey also found that the trend of decline in the product of individual technical indicators, such as fiber mean diameter, attaches great importance to industry. No. 65 issued in 2011, in order to meet the demand of construction market, dozens of rock wool on the new production line, has been put into production operation, rock wool production has rapidly increased. But under the influence of national policy and market regulation, exterior insulation with rock wool products appear a sharp drop in demand, make a lot of rock wool enterprises just put into production in trouble, some enterprises to occupy the market share, at the expense of the product performance, reduce the production cost for low-priced sales, to warm the construction engineering quality. Current rock wool industry is now facing a critical period of development, once the problems in the application of external thermal insulation, will have adverse impact on the whole rock wool industry. So rock wool production enterprises should strengthen self-discipline, strict product quality control, and maintain the healthy development of the rock wool market, prevent walked over, overproduction - price - quality and lower price again, until you exit the market, work together for rock wool products application in architectural exterior insulation.

 

In the process of the sampling type inspection, we are also delighted to see a lot of enterprise use of rock wool to other areas of the building, such as for some large workshop roof insulation, used in some construction curtain wall structure insourcing moderate used in color steel sandwich insulation layer, there are some fire belt and fire-proof sealing application the rock wool products. "Fire safety first", this is an event sponsored by the European Union for fire safety, the purpose is to improve the level of the building fire safety. Building fire safety is becoming more and more important in our country, rock wool as fire insulation materials one of the best choice, has wide application in the construction market, so the rock wool production enterprises should further improve the level of product quality, produce high quality, can satisfy the requirements of various applications of rock wool products, to promote rock wool on the application in building, promote the healthy development of the industry to work together.