HRP980233A2 - Preparation of a mineral fibre product - Google Patents

Description

The proposed invention relates to a method for determining one or more properties of a mineral fiber product, wherein the mineral fiber product is irradiated, wherein the value of the illumination intensity and wavelength is determined for part of the radiation emitted from the mineral fiber product, and where the calculation of the mentioned properties is done on the basis of correlation values.

It is often desired to determine different properties of mineral fiber products, for example, in connection with quality monitoring, or from the point of view of adjusting process parameters during the production process.

Properties to be determined in particular include binder content, oil content, surfactant content, water content, lump content, silane content and density.

A binder is added to mineral fiber products, to improve the bonding between the fibers and to obtain products with stable dimensions, at a concentration that is typically between 0 and 30 wt. %, preferably less than 10 wt. %.

Until now, the binder content in mineral fiber products was determined by determining the loss on ignition, whereby the mineral fiber product is weighed, while all organic substances charred at approx. 590°C for less than 10 minutes, then after cooling the mineral fiber product is weighed again, and the amount of organic material is determined as the weight difference between the first and second weighing.

Determination of loss on ignition gives a value for all the organic material in the mineral fiber product, which in addition to the binder also includes the oil present if necessary. In order to determine the binder content, it is therefore necessary to know the oil content in advance, or the determination of the oil content must be carried out before the determination of the loss on ignition.

To obtain a water-repellent product and to reduce the release of dust, oil is added to mineral fiber products in quantities of up to approx. 2 wt. %.

Determination of oil content was previously carried out by washing the oil from a sample of mineral fiber products using an organic solvent. The solvent and washed oil are collected in a vessel of known weight. After that, the solvent is evaporated and the container is weighed again. The oil content is determined by the difference between the weight of the container and the weight of the sample.

Water is used in various stages of production of mineral fiber products, eg for cooling or as a means of suspending binders.

An earlier procedure for determining water content was based on weighing a sample of mineral fiber products before and after drying in a drying oven. Drying takes approx. 1 1/2 hours at approx. 105°C.

Nodules are small lumps of mineral material that did not turn into mineral fibers during fiber extraction. These nodules typically represent up to approx. 30 wt. % of mineral fiber products.

Determination of nodule content was previously carried out by calcining a sample of mineral fiber products through approx. 30 minutes at approx. 590°C, after which the sample is shaken and sieved through two sieves (0.250 mm and 0.063 mm mixed) approx. 30 minutes. The nodule content is determined for each sieve with fractions as the weight of the fraction relative to the initial weight of the sample.

Until now, the density of mineral fiber products was determined by weighing a sample of known volume and calculating the density by dividing the weight of the sample by the volume of the sample.

As can be seen from the above, until now the determination of the described properties had to be done rather slowly and with cumbersome analytical methods.

In reality, the previous analytical methods are so slow that they are unsuitable for automatic process control and monitoring, because the dead time is too long, i.e. the time from taking the sample to obtaining the analysis results and possible influence on the process. Furthermore, in the case of a special process, it is necessary to process the product during sample preparation, which affects the product and complicates the analysis. Therefore, shorter analysis times are generally desirable for determining the above-mentioned properties and avoiding touching the product in connection with the analysis.

NO 162 889 describes a procedure for observing the characteristics of the binder of fibrous hasura, which can be used to determine the amount of binder and/or the degree of hardening of the binder. The procedure involves illuminating the fiber mesh with IR-light at two different wavelengths and with X-rays at one wavelength, and determining the transmission through the mesh at three different wavelengths.

The three wavelengths were chosen based on the knowledge of the frequencies at which the binder and the added curing indicator absorb or do not absorb radiation, and the tested properties are calculated based on the transmission ratio at those three frequencies.

In practice, it has been shown that it is difficult to achieve satisfactory solutions for the binder content in mineral fiber weaving with the above type of process, because the transmission through the mineral fiber weaving may be unsuitable for measurement with satisfactory accuracy if the weaving is not thin.

Furthermore, the addition of a special means for determining the amount of hardened binder is inconvenient.

Therefore, it is desirable to provide a procedure that allows measurements on different types of mineral fiber products and by which different properties of mineral fiber products can be quickly determined.

This and other objectives, which will be seen below, are obtained by the method according to the invention, which is indicated by the fact that the correlation values for the intensity of illumination and the wavelength are determined for the part of the radiation reflected from the mineral fiber product, that the correlation values are compared with the correlation values for the illumination intensity and wavelength of a comparative sample of known properties, and that the properties are calculated on the basis of the comparison.

It has been shown that the radiation reflected from mineral fiber products includes wavelength ranges in which the correlation values for the intensity of illumination and the wavelength are characteristic for the tested properties of the product.

Some of the radiation sent to the mineral fiber product is absorbed as kinetic energy in the bonds between atoms, thereby causing the individual atoms to move relative to each other. The type of individual atoms, their interconnections and position, strongly influence the frequencies of the substance that absorbs the radiation. Furthermore, the magnitude of absorption is a function of the amount of the substance in question.

By determining the correlation values for the intensity of illumination and the wavelength of reflected radiation from mineral fiber products, a relative measure for the property was obtained.

The correlation values determined for the radiation intensity and wavelength can then be compared with the radiation intensity and wavelength correlation values of a reference sample of known properties, and the properties of the sample can be calculated. Such a comparison is preferably made using a computer. Therefore, a certain number of different properties can be calculated depending on the comparative data with which the computer is calibrated.

In practice, the computer is calibrated by illuminating a comparative sample of known properties, and determining the correlation values of the intensity of the illumination and the wavelength of the reflected radiation. The known values for the properties are stored together with the correlation values of the illumination intensity and wavelength for each individual comparison sample. As a rule, calibration is better if a large number of comparison samples are used for calibration. In practice, typically 20-100 different comparison samples are used for each property for which calibration is to be performed.

It is useful that each individual sample is subjected to more than one measurement or that the measurement is carried out on several samples that have substantially the same properties.

With such a number of measurements on samples that have the same or mostly the same properties, it turned out to be useful to convert this comparative spectrum into an average value before using it for calibration. In this way, the alignment becomes much more precise.

Furthermore, this means that for calibration, comparative samples must be taken that have properties uniformly distributed over the entire area in which it is later desired to be able to determine the properties for the disputed mineral fiber product.

Finally, the calibration of the basic illumination preexcitation is done by measuring the reflection from an optically uniform standard, for example, a ceramic tile of A1203. This can correct changes in the intensity and composition of radiation from the radiation source or the environment.

To make maximum use of the measurement area, at the measured wavelengths, the reflection standard preferably has a reflection equal to or slightly higher than the maximum reflection of the product being measured.

Furthermore, during calibration and/or measurement, it is useful to carry out a basic correction of the measured data, i.e. to remove or adjust the pre-excitation data according to the reference location regarding the reflection intensity at a specific wavelength. For such a basic correction, it has proven useful to choose a wavelength at which little or preferably no change in reflectance appears as a function of changing product properties. When determining the properties of mineral fiber products, it turned out to be particularly useful to carry out a basic correction at approx. 4150 cm-1.

The calculation of the property, based on the comparison of the correlation values determined for the irradiance intensity and wavelength with the comparison values, can be carried out using a computer in a manner known per se, e.g. linear interpolation, partial least square method, multiple regression analysis, principal component analysis or some by another mathematical method known in the art for spectroscopic or regression analysis. In order to increase the accuracy of the determination for a given property, it is useful to carry out a comparison primarily for the illumination intensities at wavelengths where the differences in the illumination intensity as a function of the property are particularly significant at the contested location. Such preferred wavelengths and/or wavelength ranges can be found by mathematical methods or visual determination.

A great advantage of the process according to the invention is that the properties of mineral fiber products can be determined quantitatively with great accuracy. Furthermore, a great advantage is that multiple properties can be quantitatively determined from the same set of data.

Due to the fact that the method according to the invention is based on the measurement of radiation reflected from mineral fiber products, the properties of mineral fiber products of different designs, dimensions and/or physical nature can also be determined. Thus, the shape, thickness or density of the product is not decisive. This is why the process can be successfully applied to very porous and very compact products. Furthermore, it surprisingly turned out that there are no special requirements regarding the uniformity of the surface from which the reflection is measured.

The preferred wavelength interval according to the invention includes the infrared range from 1250 nm to 8000 nm (8000 cm-1 - 1250 cm-1). Special preference is given to the region from 1250 to 3700 nm (8000 cm-1 - 2700 cm-1).

The method according to the invention is particularly suitable for determining the binder content in mineral fiber products. If the binder contains OH groups, as for example in the phenolformaldehyde type resin, which is often used, it is particularly useful that the correlation values determined for radiation intensity and wavelength include determinations at wavelengths in the range of 2410 nm to 3570 nm (4140 cm -1 - 2800 cm-1). For other types of binders, it is preferable that the correlation values determined for radiation intensity and wavelength include determinations at wavelengths in areas where the characteristics of the bonds for the binder show absorption of radiation.

In practice, however, it surprisingly turned out that the best calibration for determining the amount of phenolformaldehyde resin according to the invention was found in the range from 2410 nm to 2985 nm (4150 cm-1 - 3350 cm-1). This is believed to be at least partially due to interference from other substances such as oils in the 2985 nm to 3570 nm (3350 cm-1 - 2800-1) region. Accordingly, the measurement is primarily performed in the range from 2410 nm to 2985 nm (4150 cm-1 - 3350 cm-1).

The method according to the invention is also suitable for determining the oil content of a mineral fiber product. When determining the oil content, it is particularly useful that the correlation values determined for radiation intensity and wavelength include determinations at wavelengths in the range from 3225 nm to 3700 nm (3100 cm-1 - 2700 cm-1) and/or in the range from 6450 nm to 7400 nm (1550 cm-1 - 1350 cm-1).

It was also found that the surfactant content in mineral fiber products can be determined by the method according to the invention.

It has surprisingly been found that the method according to the invention can also determine the content of nodules in mineral fiber products, despite the fact that they consist of an organic material.

When determining the content of nodules, correlation values measured for radiation intensity and wavelength primarily include determinations at wavelengths in the range of wavelengths from 1250 nm to 2850 nm (8000 cm-1 - 3500 cm-1).

In the same way and within the same area mentioned above, the silane content in mineral fiber products can also be determined by the method according to the invention.

Furthermore, it surprisingly turned out that the density can also be determined by applying the method according to the invention. When determining the density, the correlation values determined for the intensity of the radiation and the wavelength include primarily determinations at wavelengths in the range of wavelengths from 1250 nm to 2850 nm (8000 cm-1 - 3500 cm-1).

Other properties, e.g. water content, clay content, Al(OH)3 and/or SiO2 in mineral fiber products can be determined by comparing correlation values for radiation intensity and wavelength with comparative values for mineral fiber products in which the properties were tested. known.

It has been shown that by measuring the radiation intensity of reflected light in a larger range of wavelengths, more than one property can be determined on the basis of one and the same measured data. To be able to specify multiple properties, the only requirement is to perform the appropriate calibration for each property in question. Calibration samples can be used for more than one property, eg the reflectance spectrum of a single cause can be compared to the sample's binder content, density, nodule content, and so on.

Therefore, with a particularly advantageous implementation of the method according to the invention, two or more properties mentioned in the introduction can be determined on the basis of the same group of correlation values for radiation intensity and wavelength. It is particularly preferable to determine the content of binders and the content of lumps from values that primarily include determination at wavelengths in the range of wavelengths from 1250 nm to 3570 nm (8000 cm-1 - 2800 cm-1).

From the point of view of the efficiency of the measuring equipment or the speed of calculating the properties, the number of determinations for the correlation values determined for the radiation intensity and the wavelength can be limited to a few characteristic wavelengths.

Irradiation of mineral fiber products can be carried out using various types of radiation sources. Preferred sources of radiation for use according to the invention include primarily broad-spectrum light sources, such as incandescent lamps, halogen lamps, Nernst elements, globars (SiC), etc. The source of illumination is preferably directed directly at the product, e.g., by means of a reflector. The radiation emitted by the illumination source must include the wavelengths desired to determine the correlation values for radiation intensity and wavelength. In this regard, the proposed invention is particularly suitable for the use of a halogen lamp as a source of radiation.

It has been shown that better measurement results can be obtained if the light source is supplied with DC voltage instead of AC. By using a direct current voltage, a number of requirements for determining a good signal/signal noise can be reduced, i.e. reducing the number of current wave periods for which average measurement values would otherwise have to be calculated. Accordingly, the measurement time can be significantly shortened and the determination of the relationship of the desired value to the respective properties of the mineral fiber product is facilitated and also accelerated.

The light source preferably has a width of the same order of magnitude as a 200-300 W halogen bulb. One or more independent light sources may be used.

Various types of measuring equipment can be used to determine the radiation reflected from mineral fiber products. In principle, the measuring equipment includes a wavelength selector, which can select a relatively narrow range of wavelengths, and a detector, which can capture the radiation intensity in the selected range and re-send it in a suitable form, primarily as an electrical signal.

As a wavelength selector, any type of wavelength selector can be used, such as those described in "Fundamentals of analytical chemistry", 4th edition, D.A. Skoog et al., CBS College Publishing, 1986, including interference filters or prisms.

As a detector, any type of detector can be used, such as those also described in the above book, including thermocouples, bolometers or pyroelectric cells.

The measuring device may include, for example, an interferometer, such as that described in Modern Spectroscopy, 2nd Edition, J. Michael Hollas, Wiley 1992. Thermocouples are typically used as a detector coupled to the interferometer. The voltage signals captured by the detector are sent back to the computer where the received interferogram can be further processed. In the case of interferometers, light is more often measured in the length domain than in the frequency domain. Therefore, the received interferogram is usually Fourier transformed into a spectrum in the frequency domain. Therefore, the method can also be labeled as FTIR-spectroscopy (Fourier Transform Infra Red Spectroscopy).

The measurement can be carried out at almost any product temperature. However, as temperature changes induce pre-excitations for measurements, measurements are preferably made at a location where the product has a relatively uniform temperature profile over time.

In accordance with the preferred embodiment according to the invention, the product is thermostated at the point of measurement. This can be done by heating or cooling. The product is cooled primarily by blowing or sucking the surrounding air through the product. By thermostating the product, even more reliable determinations of product properties can be carried out.

According to another advantageous embodiment of the invention, the bias induced by temperature fluctuations is removed or limited electronically by measuring the temperature at the point of measurement of the wavelength and intensity of the reflected radiation and adjusting the measured values and/or calculated properties according to the measured temperature. Accordingly, product properties can be determined more reliably.

Measurements are especially preferably carried out at room temperature, for example at approx. 15-35°C, even better at approx. 18-30°C and even better at approx. 20-25°C. When measuring at room temperature, room air can be used for thermostating the product, which makes the thermostating process easier and more economical.

The measurement can be made at any number of different places on the product, eg top, bottom, side and/or end surface(s). In a preferred embodiment of the method according to the invention, the reflected radiation is measured from the side surface of the mineral fiber product.

In another advantageous embodiment of the method according to the invention, the reflected radiation is collected before detection from a larger surface using convex lenses.

In a further preferred embodiment of the method according to the invention, the measurement is performed at several different locations of the same product. In this way, differences in properties can be determined at different points of the product. Measurements can be made in different places by using one or more measuring devices, by moving one device in relation to the product or vice versa, or by using movable mirrors or the like.

Surprisingly, it was shown that by determining the differences in correlation values for radiation intensity and wavelength of light reflected in different directions from one surface of the product, a measure can be obtained for the dominant fiber orientation in the mineral fiber product. The orientation of the fibers in a mineral fiber product is of great importance to the insulating ability, because mineral fibers insulate better transversely to the orientation of the fibers than longitudinally with the fibers. Therefore, it is a further advantageous embodiment of the method according to the invention for determining the correlation values for the radiation intensity and the wavelength of the light reflected from the surface of the mineral fiber product in two or more directions.

It was further shown that the method according to the invention can be applied to determine the properties of mineral fiber products in a continuous production process, where the product is moved during the determination of correlation values for radiation intensity and wavelength.

Based on the knowledge of the performance, speed and direction of movement of the mineral fiber product in relation to the measuring equipment and the time of determination of the individual properties of the mineral fiber product, the differences in properties at different points of the product can be calculated.

With several measuring devices placed at different points on the production line for mineral fiber products, the differences in properties between products at various stages of the process can be calculated. This can generally be used to observe the efficiency of e.g. water evaporation, compaction or the addition of binders.

A particular advantage of the process according to the invention is that the determination of the properties is so rapid that the values for the individual properties can be used to adjust the process parameters related to the production of mineral fiber products. Determining the binder content in the mineral fiber fabric by the method according to the invention can be used, for example, to automatically adjust the addition of the binder.

In particular, the advantages of the invention are obtained by determining the properties of mineral fiber products made from man-made mineral fibers, for example glass, stone and/or slag fibers, such as those used in plates, sheets, pipes and products of various of a form for thermal insulation, fire protection purposes, noise attenuation or noise regulation, or for cement or plastic materials or other materials reinforced with mineral fibers, such as fillers, or as a plant growth agent.

Mineral fiber products according to the invention are primarily non-woven.

The invention also relates to a device for carrying out various embodiments of the process according to the invention, which includes appropriate means for carrying out the individual stages of the embodiments as described above.

Accordingly, the invention relates to a device for determining one or more properties of mineral fiber products, which includes means for illuminating mineral fiber products, means for determining correlation values for radiation intensity and wavelength for part of the radiation emitted by mineral fiber products , and means for calculating said properties on the basis of correlation values, which is characterized by the fact that the means for determining correlation values for radiation intensity and wavelength are arranged to detect at least part of the radiation reflected from the mineral fiber product and that the means for calculating properties include comparative data indicative of correlation values for radiation intensity and wavelength for compared samples of known properties and a processor for calculating the properties of mineral fiber products by comparing detected correlation values for radiation intensity and wavelength for part radiation emitted by mineral fiber products with the mentioned comparative data.

The invention further relates to the use of the device according to the invention for determining one or more properties of mineral fiber products.

In the following, the invention is described in more detail, the description being based on the drawings of which

Figure 1 shows a schematic measuring arrangement for measuring reflected IR radiation,

figure 2 shows a schematic device with convex lenses,

Figure 3 shows a schematic measuring arrangement for measuring on two surfaces of mineral fiber products,

Figure 4 shows a schematic measuring arrangement for measuring light sent in two directions from the same point.

Figure 1 shows a mineral fiber product 1, seen from above, and a cross-section of an IR-measuring device 2. The IR-measuring device includes a monochromator 3 and a detector 4 that records radiation intensities at different wavelengths of light reflected from the side surface of the mineral fiber product, marked with two dotted lines. The measured values are transferred to the computer, which is not displayed. The radiation arriving at the mineral fiber product is indicated by two dashed lines as a slight cone, and comes from two halogen lamps 5 which are supplied with DC voltage from a DC voltage source 6.

Figure 2 shows a cross section of the mineral fiber product 1 and the IR measuring device 2, which by means of convex lenses 7 captures radiation from the entire thickness of the mineral fiber product, as indicated by dotted lines. The radiation to the mineral fiber product comes from a broad spectrum light source, not shown.

Fig. 3 shows a cross-section of the mineral fiber product 1 and the IR measuring device 2, which can capture light from the bottom and the surface of the mineral fiber product via the rotatable inclined mirror 8 and the stationary inclined mirrors 9. Paths of reflected radiation are marked with dotted lines. The radiation to the mineral fiber product comes from a broad spectrum light source, not shown.

Figure 4 shows the measuring arrangement for measuring the radiation sent in two different directions from the location on product 1 of mineral. fibers. The IR-measuring device 2 captures the radiation via the tilted rotary mirror 10 and the stationary tilted mirrors 11. The path of the reflected radiation is marked with dotted lines. The radiation to the mineral fiber product comes from a broad spectrum light source, not shown.

In the following, the invention is described in more detail by means of examples.

Example 1

This example describes a measuring arrangement for carrying out the process according to the invention in the production of mineral fiber products.

To determine the properties of the moving mineral fiber weave on the conveyor belt, a commercially available interferometer was placed at a distance of approx. 50 cm from the place on the conveyor belt where the mineral fiber weave will pass. The device is placed in such a way that the device will be able to measure the light reflected from the side surface of the fabric. A strong light source, such as a 250 W halogen bulb, connected directly to a DC voltage source, is placed at a distance of approx. 40 cm from the place on the conveyor belt where the mineral fiber weave will pass, and in such a way that the area of the side surface of the mineral fiber weave is illuminated from which the reflected radiation is captured by the IH-measuring device.

The IR-measuring device has convex lenses that can collect the radiation sent up the entire height of the mineral fiber weave before it is captured by the device.

The IR-measuring device is connected to a computer that can collect and process the measured IR-data using a program. The measuring device is connected to electricity and heating approx. 4 hours before its calibration or use for measurement.

To compensate for temperature changes in mineral fiber weaving, a pyrometer is placed at a suitable distance from the conveyor, where the mineral fiber weaving will pass. The pyrometer is set up in such a way that the pyrometer will be able to measure the heat transferred by radiation (i.e. the temperature) of the area of the mineral fiber weave in which the IR-measurement is performed.

Example 2

This example is largely identical to the main subject of example 1, except that compensation of temperature changes in the mineral fiber weave is accomplished by means of a suction and/or blowing device placed near, but not in, the area of the mineral fiber weave where the IR measurement is performed . The suction and/or blowing device is placed so that, if necessary, a thermostated and/or temperature-controlled air stream, which is introduced by the device, passes through the mineral fiber fabric, which stabilizes the temperature of the fabric at the place where the IR-measurement is performed.

Example 3

This example describes the method of calibrating the measuring equipment for the implementation of the method according to the invention.

The basic light is determined by placing a ceramic tile (Al2O3) in the place where the mineral fiber fabric will be exposed to radiation and is measured 50 times. The illumination intensity is calculated as an average value and stored in the computer.

Then, each comparison sample is alternately placed where the mineral fiber fabric will be exposed to illumination and measurement, after which the correlation values for radiation intensity and wavelength for the comparison sample are measured and stored. After the measurement, a value is entered for the characteristic property of the comparison sample, and the value is stored in the computer together with the correlation values determined for the radiation intensity and wavelength.

The temperature of the sample is measured and/or controlled as necessary, eg as described above in Example 1 or 2, and if measured, the temperature of the sample is stored in the computer along with the correlation values determined for the radiation intensity and wavelength. The measured sample preferably has the same and/or at least a known temperature.

For each comparison sample, the range of wavelengths from 1250 to 3570 nm (8000 cm-1 - 2800 cm-1) is measured with a measurement for every thirty-second wave number, and the input region is measured 20 times, after which the computer calculates the average of the series of 20 measurements to smooth out random deviations.

During calibration, 30 comparative samples were used to determine the binder content, which have different binder content in the range of 1.0 wt. % to 5.0 wt. %.

During calibration, 30 comparative samples were taken with different content of lumps in the range of 20 wt. % up to 40 wt. %.

Example 4

This example describes an embodiment of the process according to the invention in which the same measuring schedule as in example 1 is applied, and where the measuring schedule of calibration for binder content and lump content as described in example 2 is applied.

A mineral fiber fabric 190 cm wide and 35 cm thick, moving at a speed of 15 m/min, passes through the measuring zone as described in Example 1, the fabric is illuminated with a halogen lamp, and the reflected IR light is captured and recorded with an IR-measuring device. The temperature of the fabric is preferably observed continuously, and if necessary it is controlled and/or measured as stated in examples 1 or 2.

The measuring device measures continuously in the range of wavelengths from 1250 to 3570 nm (8000 cm-1 - 2800 cm-1) with a measurement for every thirty-second wave number, and the entire range is measured 20 times, after which the computer calculates the average value for a series of 20 measurements to smooth out random deviations. Series of average value measurements for correlation values of radiation intensity and wavelength and, if necessary, measured temperature are compared using a computer with correlation values for radiation intensity and wavelength and, if necessary, with the measured temperature of comparative samples, which are known from the calibration carried out in accordance with example 3 .Based on the calibration, the computer calculates the binder content based on the calibration for the binder content, and the lump content is calculated based on the calibration for the lump content. The results are saved to a file and printed on the screen.

The determination of binder content and lump content is carried out continuously, and the results are printed every ten seconds, so that the properties of mineral fiber weaving can be monitored. The computer is also equipped with a device that sends a signal if the determined values deviate by more than 0.2 percent from the previously entered set value.

The calibration of the measuring device is checked approx. every week with a reference sample, and subsequent calibration is performed as necessary as described in example 3.

The basic light is determined and subsequent calibration is performed for each change of approx. every 4 hours by measuring on a ceramic plate (Al2O3), as described in example 3.

Example 5

This example refers to the determination of the accuracy of the binder content measured by the method according to the invention in comparison with that measured by the method according to the state of the art.

A mineral fiber product with a known binder content of 3.83 wt. % and without other organic substances was divided into several samples.

Half of the samples were randomly selected for analysis by a state-of-the-art method that includes determination of loss on ignition, whereby mineral fiber samples are weighed, all organic material charred at approx. 590°C for around 10 minutes, the mineral fiber product is weighed again after cooling and the amount of binder is determined as the difference in weight between the first and second weighing. The whole procedure takes about 45-60 minutes.

The binder content determined by the state-of-the-art method was 3.83±0.26 wt. %.

The remaining samples were measured using the measurement schedule shown above and were properly calibrated to determine the binder content.

By carrying out one measurement (1 wavelength range search) lasting approx. After 5 seconds, the binder content of 3.83±0.38 wt. was determined for each sample. %. By increasing the number of measurements to 7 measurements for each sample (approx. 30 seconds), the binder content was determined to be 3.83±0.14 wt. %.

As can be seen from these results, the method according to the invention can quantitatively determine the properties of mineral fiber products and actually at the same time with greater accuracy than the method according to the state of the art.

Example 6

This example relates to the determination of the accuracy for the total loss on ignition measured by the method according to the invention. Everything is set up as in the previous examples and the appropriate calibration is applied.

Using the method according to the invention, a certain number of samples with a known content of organic matter were measured a certain number of times. The time of each measurement varied from 3 seconds to 39 seconds, corresponding to 5 to 100 searches of the wavelength region. The deviation from the established values of loss on annealing is indicated in the table below:

Table 1

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Claims (14)

1. Procedure for determining one or more properties of a mineral fiber product, by which the mineral fiber product is irradiated, where appropriate values of radiation intensity and wavelength are determined for part of the radiation emitted from the mineral fiber product, and where the calculation of the mentioned properties is carried out on the basis of correlation values, indicated by the fact that the correlation values for radiation intensity and wavelength are determined for the part of radiation reflected from mineral fiber products, that the correlation values are compared with the correlation values of radiation intensity and wavelength of samples of known properties, and that the properties they calculate on the basis of comparison. 2. The method according to claim 1, characterized in that the correlation values for radiation intensity and wavelength are determined at wavelengths in the range from 1250 to 8000 nm. 3. The method according to claim 1, characterized in that the correlation values for radiation intensity and wavelength are determined at wavelengths in the range from 1250 to 3700 nm. 4. The method according to any of the preceding claims, characterized in that the binder content, oil content or surfactant content is calculated. 5. The method according to any of the preceding claims, characterized in that the content of nodules, the content of silanes or the content of surfactants is calculated. 6. The method according to any of the preceding claims, characterized in that two or more properties are calculated on the basis of the same group of correlation values for radiation intensity and wavelength. 7. The method according to any of the preceding claims, characterized in that the mineral fiber product is moved during the determination of correlation values for radiation intensity and wavelength. 8. The method according to any of the preceding claims, characterized in that the mineral fiber fabric is illuminated with a broad-spectrum light source, such as a halogen lamp. 9. The method according to any one of the preceding claims, characterized in that the light source is supplied with direct voltage. 10. The method according to any of the preceding claims, characterized in that the correlation values for radiation intensity and wavelength are determined for radiation reflected from the surface of the mineral fiber product in two or more directions. 11. The method according to claim 10, characterized in that the dominant orientation of the fibers on that surface is calculated. 12. Use of a property value calculated by a method according to any one of the preceding claims, characterized in that it is used to adjust process parameters related to the production of mineral fiber products. 13. Device for determining one or more properties of mineral fiber products, which includes means for illuminating mineral fiber products, means for determining correlation values of radiation intensity and wavelength for part of the radiation emitted from mineral fiber products, and means for calculating said means on the basis of correlation values, indicated by the fact that the means for determining the correlation values of the radiation intensity are set to detect at least part of the radiation reflected from the mineral fiber product and that the means for calculating the properties include comparative data indicative of the correlation values for the radiation intensity and the wavelength for comparative samples of known properties, and a processor for calculating the properties of the mineral fiber product by comparing the detected correlation values of radiation intensity and wavelength for the part of the radiation emitted from the mineral fiber product with the reference but comparative data. 14. Use of the device according to claim 13, characterized in that it is used to determine one or more properties of mineral fiber products.