SI9520007A

SI9520007A - Method and device for polymerising binders in fibrous materials especially mineral wool insulation

Info

Publication number: SI9520007A
Application number: SI9520007A
Authority: SI
Inventors: Frederic Mertz; Pascal Chartier; Christian Decker
Original assignee: Saint Gobain Isover
Priority date: 1994-06-17
Filing date: 1995-06-16
Publication date: 1996-06-30
Also published as: PL313167A1; BR9506267A; KR960705097A; AU2792795A; CA2168014A1; FI960127A; FI960127A0; CZ337595A3; DE4421254A1; WO1995035402A1; ZA954731B; CN1129020A; NO960018D0; NO960018L; HU9503489D0; EP0717798A1; HUT72828A; JPH09505117A

Abstract

The invention concerns a method and a device for polymerising substances in fibrous materials, in particular binding agents in mineral wool materials for insulation purposes, wherein the fibrous material having a given thickness (d) is subjected to UV irradiation in order to polymerise the substance having the form of a prepolymer impregnating the fibres, said irradiation of the material is carried out at a sufficiently high intensity level (IUV) to bring about, at a maximum depth (d) of intended polymerisation, a residual intensity exceeding such threshold value at which polymerisation of the selected binding agent under the influence of UV radiation is ensured within a given time limit, such time limit, however, precluding any undesirable degradation, due to the effects of the radiation, of organic substances in the portion at the surface of said material, and wherein the duration of irradiating a given surface unit of said material is kept within said time limit.

Description

Process and preparation for polymerisation of substances in fibrous materials, in particular binders in mineral wool materials for insulation purposes

The invention relates to a process for the polymerization of substances in fibrous materials, in particular binders in mineral wool materials for insulating purposes, wherein the fibrous material, which has a certain thickness and which can optionally move continuously along the production line, is subjected to ultraviolet radiation to polymerize a substance in the form of a fiber impregnating prepolymer and to a device for polymerizing a substance in fibrous materials, such as, in particular, a binder in fibrous wool material for insulation purposes, the device comprising at least one ultraviolet radiation source.

Such a technique is known from U.S. Patent No. 5,257,874. The purpose of this known art is to uniformly polymerize the material throughout its thickness. Based on the fact that the energy emitted in the material by ultraviolet rays decreases exponentially with increasing distance from the surface of the material, it takes a long time to process to achieve maximum uniformity of polymerization. In this case, according to U.S. Patent No. 5,275,874, the radiation flux density after passing through the thickness of the material drops to one percent of the incident flux density when the material travels below a plurality of ultraviolet lamps, essentially analogous to the passage through a polymerization furnace in conventional thermal polymerization. .

In such processing, it is known from the experience within the scope of the present invention that the organic constituents on the surface of mineral wool material are inevitably osmotic and charred. Due to the rapid decrease in intensity, that is to say, per unit area of power input, with the depth below the irradiated surface, the required energy input is so high that it results in the charring or ossification of the organic components at the surface, e.g. binders on the irradiated surface of mineral wool material.

Accordingly, the invention is based on the task of providing a method according to the introductory part of claim 1, thereby enabling the desired polymerization even at considerable depths of material below the irradiated surface without undesirable undesirable effects on the surface of the material.

This task is solved by irradiating at a sufficiently high intensity level so that at a maximum depth of the intended polymerization the residual intensity is exceeded beyond such a threshold that the polymerization of the selected binder under the influence of ultraviolet radiation is ensured within the given time limits. However, these time limits prevent any undesirable degradation due to the effects of radiation on organic matter in the region near the surface of the material, and to keep the irradiation time of the surface unit of the material within these time limits. In the case of fibrous material continuously moving along the production line, this duration shall also be chosen in accordance with the speed of the production line.

In the course of research into the present invention, it has been found that the materials that are suitable as prepolymers have threshold values for the level of intensity, that is, for the irradiance power per unit area above which polymerization takes place within a very short periods of time, or almost instantaneously. Increasing the intensity level above this threshold does not significantly accelerate the polymerization without adversely affecting it. The rise in temperature on the irradiated surface leading to degradation effects, on the other hand, is essentially proportional to the duration of irradiation, with the rate of increase of temperature naturally increasing depending on the intensity level.

In the case of ultraviolet radiation, heat is released according to the intensity of the radiation, either due to the thermal radiation emitted by the ultraviolet source at the same time or from the energy losses of the ultraviolet radiation, which is thus converted into thermal radiation; these effects are most evident at the surface of the material, since they occur at the highest temperatures and allow for decomposition phenomena as soon as a certain temperature limit is exceeded.

These phenomena occurring in parallel but with different time course are used in the present invention by first determining the intensity threshold level at which polymerization is carried out rapidly, e.g. within 0.2 s. The surface unit under consideration is then irradiated for such a time and the level of radiation intensity on the surface can be raised so that the temperature rise during this predetermined time interval, e.g. 0.2 s, still remains below a given temperature limit above which degradation effects can be expected. This maximum intensity, which can be used for a predetermined short period of time, however, due to the drop in intensity in the material, limits the depth within which the intensity remains above the threshold value and within which, therefore, homogeneous polymerization is possible.

As each surface unit is thus exposed to high intensity radiation for only a short period of time, irradiation can be carried out in a confined space to save space on the production line. In the case of a continuously moving fabric of material on the production line, the irradiation time of each surface unit should be chosen to be consistent with the line speed, generally between 0.1 m / s and 1 m / s.

If the radiation intensity level exceeds 500 mW / cm ² , and especially 1 W / cm ² and in a particularly preferred way exceeds 2 W / cm ² , then commercially available ultraviolet sources may be used at the expense of efficiency on the one hand, while on the other hand, high intensity levels on the surface are still enabled. As is known in itself, ultraviolet radiation sources in the wavelength range above 250 nm are preferred, preferably above 310 nm due to the selectively increased permeability of the mineral wool material in this area.

The irradiation duration of the surface unit is preferably less than 10 s and is preferably less than 1 s and preferably less than 0.5 s.

In many conventional machining processes, mineral fibers are made of molten glass to which a substance is added, e.g. prepolymer binder, during deposition as a woolen layer and then this substance, e.g. binder, polymerizes. In such a case, the mineral wool material still has a relatively high temperature when the substance is polymerized so that the rise in temperature on the surface side to the temperature limit under the influence of radiation starts from a relatively high initial temperature. Particularly in such a case, the mineral wool material is preferably cooled to as low a temperature as possible prior to irradiation, in order to allow a higher allowable temperature rise due to radiation treatment. However, due to the short irradiation with irradiation, the short irradiation period has no effect that would justify the associated expenditure. The use of the process according to the invention, on the other hand, is particularly preferred in all those manufacturing processes where the mineral wool material is polymerized at a lower temperature, preferably at ambient temperature. This is e.g. when the binder is introduced in the form of steam or aerosol as known from DE A 44 06 863 and DE A 4410 020, respectively.

The fraction of oxygen contained in the fibrous material, which is about 21% in normal treatment than in the surrounding atmosphere, is preferably reduced to less than 10% during irradiation, even better below 5% and in a particularly preferred manner to less than 1% . In the case of conventional polymerization using radicals, this measure prevents the free radicals of the substances that are to be polymerized and which are generated by radiation, preventing them from being occupied by oxygen, and thus preventing the failure of polymerization at these sites. This is especially important for monomer films of very low thickness and low irradiation intensity.

The irradiation is preferably carried out on both major surfaces of the material so that the radiation energy penetrates the thickness of the material from both sides. In this way, the penetration depth can more than double when the penetration depths overlap in the middle of the material. This overlap effect is particularly well used if both sides are irradiated simultaneously, so that at a certain point inside the material, the energy from the irradiation of both sides is simultaneously present.

The polymerization does not need to be homogeneous throughout the thickness of the material. In particular, in the case of bilateral irradiation, it may be sufficient to polymerize the layers of material adjacent to the surface and to leave a more or less wide inner layer with significantly reduced polymerization. In the case of binder polymerisation, the desired increase in mechanical strength is achieved in the outer regions so that the flexural resistance, which is often the most important, is only severely affected by the lower mechanical strength in the center region of the plate. Incomplete polymerization is often also acceptable where other properties besides flexural resistance are important, e.g. surface sealing, surface strength or the like. When polymerizing substances other than binders, non-homogeneous thickness polymerization may prove advantageous, depending on the function of the substance and the use of the product.

In the case of non-homogeneous thickness polymerization, it may also be advantageous, as described in DE A 44 06 863 or DE A 44 10 020, to introduce a non-homogeneously distributed substance into the material. Thus, e.g. in the case of a binder in this way, a greater concentration of the binder is achieved in the regions near the surfaces than in the center region of the plate, which results in the production with the desired best use of a given amount of binder.

Multifunctional acrylic and methacrylic compounds, as known per se, are particularly suitable as prepolymer. Further suitable substances are prepolymers in the form of monomers, oligomers or polymers comprising polymerizable unsaturated functional groups, such as acrylic, methacrylic, vinyl, vinyl ether, allyl or maleate groups, which may react in terms of chain extension and / or crosslinks. The binder may be a mixture of these compounds and comprise a photoinitiator to allow for polymerization via ultraviolet light. It has been found that prepolymer compositions comprising epoxyacrylates are particularly preferred for the present invention.

The apparatus of the invention for carrying out the method of the invention comprises the means for focusing ultraviolet radiation on at least one focused beam of small width.

Such focusing can achieve a high level of surface intensity.

Particularly in the case of polymerization on a liquid production line, it may be advantageous to focus in a linear fashion, e.g. extending beyond the width of the fabric made. The width of the linearly focused beam can then be matched to the transport speed of the fabric fabricated to achieve the desired irradiation duration of each surface unit without the presence of moving parts.

Alternatively, focusing may also be done in the form of a point, whereby the high-intensity thin beam created in this way travels through the material desired in a predetermined pattern. In this way, a substance can be polymerized in a fibrous material having an uneven surface in the case of molded products, e.g. tubular sections having the shape of a hollow cylinder. This shifting of the focused beam may, e.g. gets with very limited expenditures using a swinging mirror. The high intensity or power density of such a point-focused beam allows for deep penetration depths for the polymerization of substances having particularly short polymerization times. Notably, such thin-beam oscillatory motion allows for good adaptation to different line speeds. For certain applications, it may be sufficient to illuminate only a portion of the entire surface of the fibrous material with a beam and to allow intervals at which polymerization is unnecessary or actually occurs due to the effect of close irradiation.

In a preferred way, the focused beam is directed to the final focus, i.e. the beam is collected at a point and does not exist from parallel beams. Thanks to proper focusing, the focal point can be positioned at the desired depth of material so that a relatively higher intensity is obtained there on a smaller surface, although it is weakened by scattering on fibers lying higher. This type of focused beam design is particularly suitable in the case of a line-shaped focused beam.

Further details, features and advantages of the invention are apparent from the following description of embodiments with reference to the drawing in which FIG. 1 shows a characteristic function of the intensity level with respect to the thickness of the mineral wool product layer subjected to bilateral ultraviolet irradiation, FIG. 2 shows the degree of conversion as a function of time at different intensity levels; FIG. 3 shows the heating of the mineral wool material surface at different intensity levels; FIG. 4 shows the relationship between the intensity level and the polymerization by the thickness of the mineral wool product plate that was. treated according to the invention by bilateral ultraviolet radiation, FIG. 5 shows a schematically simplified view of a device according to the invention having linear focusing of ultraviolet radiation, and FIG. 6 shows a schematically simplified representation of a device according to the invention with a beam focused at a point on mineral wool material.

In order to facilitate understanding, the same reference marks are used for identical or corresponding parts, respectively. graphically represented functions.

FIG. 1 illustrates the characteristic function of the local intensity level of the ultraviolet

Ί radiation depending on the thickness of the fiber material, e.g. for a mineral wool product which is subjected to two-sided ultraviolet irradiation of its surface.

The wall thickness or depth d of the mineral wool product having a wall thickness of 12 cm is shown as an abscissa or X axis. The left ordinate or the Y axis shows the intensity level of 1 ^ ulraviolet radiation from 0 to 100% and the right ordinate or Y axis shows the intensity level of 1 ^ ulraviolet radiation from 0 to 2000 mW / cm ² . In the present case, 2000 mW / cm ² corresponds to the intensity level of 100% ultraviolet radiation.

On the right side of the right ordinate on one side and on the left side of the left ordinate on the other are drawn arrows pointing towards the center of the image and illustrating the incident ultraviolet radiation with energy hv. Since irradiation is performed on both sides of the mineral wool product, the intensity level d, illustrated by curve 1, runs approximately symmetrically to the center line, so that only the left half of the diagram will be considered initially. It can be seen that the intensity level 1 ^ drops sharply after a relatively small depth d of penetration. From the initial intensity level I _uv with a value of 100% on the mineral wool surface, the intensity level 1 ^ in this case falls below 50% after less than 1 cm of penetration, and at a penetration depth of 2 cm it is already below 10% and in the central area of the product from mineral wool is only below 5% of the intensity level of 1 ^ incident radiation on the surface. This sharp decrease in the intensity level 1 ^ in the depth of penetration is caused, on the one hand, by the low permeability of ultraviolet radiation through the mineral wool material and, on the other hand, by the conversion of ultraviolet radiation energy into thermal energy even in the thickest layers of mineral wool material without associated polymerization. .

The first estimate of the intensity curve 1 as shown leads to the result that satisfactory polymerization of the substance in the fiber materials must be limited to areas of the material near the surfaces, since the intensity level of 1 ^ ultraviolet radiation falls too fast, thus making it impossible to provide a sufficiently high residual intensity in the center field to achieve satisfactory polymerization there. Therefore, if the intensity level of 1 ^ radiation is raised to such a value that the central area of the fibrous material can still be satisfactorily polymerized, this would result in such high intensity levels on the surface that no damage to the material on the surface would be avoided, e.g. carbonisation or ossification of surface organic constituents, e.g. polymerizable substance or binder.

In FIG. 2 shows the function of time-dependent polymerization of fibers in fibrous materials at different intensities of ultraviolet radiation. The abscissa or X axis shows the time t of irradiation in seconds from 0 to 1.5 s. The left ordinate or the Y axis shows the associated P conversion rate due to a 0 to 100% polymerization. Curves I of _UV1 to 1 ^ 7 show different intensities of 1 ^ ultraviolet radiation with e.g. I _UV1 = 2 mW / cm ² , = 5 mW / cm ² , 1 ^ = 11 mW / cm ² , 1 ^ = 25 mW / cm ² , 1 ^ = 55 mW / cm ² , = 128 mW / cm ² in 1 ^ = 220 mW / cm ² . Thus the intensity level 1 ^ rises from to I _UV7 .

All seven curves have common characteristics in common. They are, first, a common starting point in the starting 0 graph. After a short interval, this common starting point is followed by the rise of the curve with a positive gradient dP / dt, followed by an almost linear region of increase with a constant positive gradient dP / dt. This area of linear ascension is then followed by a declining increase in all the curves shown, that is, increasing with a decreasing positive gradient dP / dt until it reaches a nearly horizontal linear section without further increase, i.e. with a constant gradient of dP / dt near zero. The limit of the P conversion rate with the polymerization achieved in this continuous section can be denoted as the saturation limit of the P polymerization step, which occurs at a given intensity level of 1 ^ radiation.

The steep gradient of linear rise in the front of the curves increases with increasing intensity of 1 ^ ultraviolet radiation and is not very different in the case of the 2 mW / cm ² curve, while a very steep gradient is present in the IUV7 curve of 220 mW / cm ² . The angle of transition from the steep rise in the front of the curves to the horizontal, almost linear region of the curves is not very different in the case of two intensity levels IUV1 and 1 ^ 2, in the case of the intensity level 1 ^^ it is very clearly distinguished, while the intensity levels 1 ^^ to perform distinctly different transition arcs from sharp rises to constant curve sections. In addition, this transition arc occurs at an earlier time point with an increasing intensity level of 1 ^.

This means that in cases of lower intensities of 1 ^ ultraviolet radiation, the mineral wool material should be irradiated for a relatively long time until there is no further increase in polymerization, which is low at any stage. However, if a relatively high ultraviolet radiation is used to irradiate mineral wool material, the high degree of polymerization is achieved within a very short period of time and maximum is reached very quickly and then can no longer increase but remains constant. This means that there is a limit for the irradiation time for each significant radiation intensity level within which the maximum polymerization is achieved, and a further increase of the polymerization cannot be achieved by extending said boundary against longer irradiation.

In the example shown, there is a sharp increase in polymerization at an intensity level of 1 ^ by 220 mW / cm ² after about 0.05 s and reaches its maximum value after the irradiation duration from 0.2 s to 0.3 s, in which about 80%. This shows that at a sufficient intensity level of irradiation, a maximum of high-level polymerization can be achieved after a short irradiation time.

The surface heating of fibrous or mineral wool material at different intensity levels of ultraviolet radiation is further explained in more detail, with reference to FIG. 3. The abscissa or X axis represents the time tv seconds. The ordinate or the Y axis shows the surface temperature of the mineral wool material in ° C. The horizontal dashed line at 20 ° C represents the ambient temperature as a reference value. In the present case, it starts with the assumption that the mineral wool material is at a temperature of about 20 ° C before irradiation begins. The second horizontal dashed line at 20 ° C shows the upper limit of thermal loading of organic constituents such as polymerizable substances or the binder of conventional mineral wool material on its surface. In the graph itself, the temperature function, as a function of time, is shown for two intensity levels I _UV1 and I _UV2 , of which I _{UV1 is the} lowest and in this case 11 mW / cm ² and I _{UV2 is the} highest intensity level and in this case is 2000 mW / cm ² . It can be observed that the surface temperature of the mineral wool material rises almost proportionally with time at a constant intensity level of ultraviolet radiation. This linear temperature rise depends on the intensity level 1 ^, so that the gradient of this straight temperature line increases with increasing intensity level. If the mineral wool material is irradiated with high levels of ultraviolet radiation, the temperature limit, e.g. 200 ° C, which causes damage to the surface of the mineral wool material, is reached within a relatively short time. New knowledge of these linkages can be exploited in the teachings of the present invention by reducing irradiation periods when mineral wool materials are irradiated to such an extent that the arc of transition from steep growth to maximum polymerization can be precisely reached within that period. This allows the use of intensities that do not cause surface damage at short irradiation times, although after prolonged irradiation would lead to surface damage, and yet allow the introduction of sufficient intensity into the middle of the material to allow sufficient polymerization of P within such irradiation period.

Together with the physical connections shown in FIG. 1 and 2, it becomes clear that there is a working area, which depends on the intensity level I _uv ultraviolet radiation, the thickness d of the mineral wool of the period t of irradiation and shows the temperature limit, in which the possible maximum and rapid polymerisation of substances in fibrous materials , without having to expect superficial damage.

Mineral wool material may be present at high temperature before irradiation due to pre-treatment steps. Further heating due to irradiation can then cause the temperature limit to be exceeded relatively quickly, thereby causing thermal loading of organic components such as a polymerizable substance or a binder of conventional mineral wool material on its surface. Thus, cooling of the mineral wool material prior to irradiation, e.g. by means of suitable preparations, such as e.g. proposed in DE A 44 06 863 or in DE A 44 10 020, which can prevent rapid rise in temperature due to irradiation to values above the temperature limit and thus damage to the surface.

The connection on the basis of the present invention between changes in intensity level on the one hand and polymerization on the other and the thickness d of the mineral wool product upon bilateral ultraviolet irradiation is shown in FIG. 4. Displays the abscissa in the same manner as in FIG. 1 thickness d of mineral wool product, in the case of 12 cm. The left ordinate shows an intensity level 1 ^ from 0 to 100% and the right ordinate shows an intensity level 1 ^ from 0 to 2000 mW / cm ² . Here, the intensity level 100% corresponds to 2000 mW / cm ² . Additionally, polymerization P from 0 to 100% on the right ordinate is shown. Similar to FIG. 1 arrows hv on the right and on the left symbolize the energy supply by ultraviolet radiation. Curve 1 shows again the variation of the intensity level over the thickness d similar to that in FIG. 1. Curve 3 shows the change in polymerization on irradiation from the left and curve 4 shows the change in polymerization P on irradiation on the right. Irradiation occurs on both sides, and the development of polymerization P results in the loading of curves 3 and 4, which is graphically represented by curve 2. In this case, curves 3 and 4 are approximately mirror-like with respect to the center of the mineral wool material as their axis , so that curve 2 is also approximately symmetrical with respect to the center region.

The curves 1 and 3 are discussed first, which will show the relationship between the change in intensity level and the polymerization of P. As long as the tensile level 1 ^, which falls sharply after a small penetration depth in curve 1, still exceeds a sufficiently high limit, Nearly maximum polymerization of P. occurs. If this limit is not reached, curve 3 drops also and finally reaches 0. The same applies to curve 4 when irradiated to the right. Taking into account the explanations given in FIG. 1 to 3, it becomes clear that almost uniformly good polymerization can be achieved in mineral wool material over its entire thickness at a sufficiently high initial intensity of ultraviolet radiation on the surface of the mineral wool product, which then drops rapidly in a typical manner but not further than up to a certain intensity limit at which polymerization is still substantially occurring, and at an appropriately selected irradiation duration. In this way it would be possible to polymerize mineral wool materials throughout their thickness. It is, for example. by influencing the irradiation time, the substances in these mineral wool materials can be polymerized only near their surfaces, and no polymerization or only reduced polymerization in their central regions is achieved.

Non-polymerized parts of a substance in a fibrous material are subjected to aging due to their reaction with oxygen from the atmosphere and other reactants, thereby eliminating their reactivity and making the substance inert.

FIG. 5 shows a schematically simplified representation of an embodiment of a device according to the invention having linear focusing of ultraviolet radiation. The source of ultraviolet radiation 10, preferably a linear source of ultraviolet radiation, is located in the first focal point of the reflector 12, the cross section of which is preferably in the form of a parabola or ellipse. Ultraviolet radiation emitted by the source 10 of the ultraviolet radiation is focused on the second focal point 14 · by means of a reflector 12. The second focal point 14 is located near the surface of the mineral wool material 16 to be irradiated or in the mineral wool material . The mineral wool material 16 may be a mineral wool material fabric and is e.g. transported on a transport device not shown below at least one ultraviolet radiation source 10 and / or above at least one ultraviolet radiation source 10 and thereafter travel a linearly focused bundle 18 of minimum width b approximately perpendicular to the transport direction.

FIG. 6 shows a schematically simplified representation of a device according to the invention forming a focused bundle, which is point-shaped on mineral wool material. The origin of the ultraviolet radiation 10 is point-like in this case and is located in the first focus of the mirror 12, which is approximately semielipsoid. With the help of this semielipsoid reflector, ultraviolet radiation from a radiation source 10 is focused in a different focus 14.

The second focus 14, on the other hand, is located close to the surface or inside the material 16 of mineral wool, e.g. may be made of three-dimensional particles and whose surface contour is sensed by an ultraviolet beam 18 at an angle of incidence about 90 ⁰ to the plane normal of the corresponding irradiated plane element. This can be achieved by suitable movable equipment for the source 10 of the ultraviolet radiation which is not shown and / or by means of movable mirror units which are also not shown.

Prepare with FIG. 5 and 6 use end foci at the level of the mineral wool material to be treated. Quite similar effects can be achieved when using thin beams with infinite foci, that is, parallel beams.

The oxygen content of the fibrous material during treatment should preferably be reduced below 10%, or even preferably below 5%, or even most preferably below 1%, practically completely avoiding the case in which the free radicals of the substance to be polymerized, produced by ultraviolet radiation using photoinitiators react with oxygen and polymerization at this site is prevented.

If the oxygen content of the fiber material is sufficiently reduced, a more complete polymerization of the substance can be achieved. A further advantage of using an inert atmosphere is that it reduces the possible formation of ozone, because in a predominantly inert atmosphere oxygen molecules that can be cleaved by the energy of ultraviolet radiation to form oxygen radicals and which can then form ozone are no longer present.

Reduced oxygen content can be easily achieved by washing the mineral wool material with another gas, e.g. with nitrogen, or in a more economical way with carbon dioxide or water vapor.

For ISOVER WITH 1NT-GOBAIN: L.) i. ''/' ΐ.Ο.Ο.

Claims

A process for the polymerisation of a substance in fibrous materials, in particular binders in mineral wool materials for insulating purposes, in which a fibrous material having a given thickness (d) and which can optionally move continuously along the production line is subjected to ultraviolet irradiation to polymerize a fiber-impregnated prepolymeric substance, characterized in that the irradiation of the material is carried out at a sufficiently high intensity level (1 ^) to achieve a residual intensity exceeding such value at the maximum depth of the intended polymerization a threshold at which the polymerization of the selected binder under the influence of ultraviolet radiation is ensured within a given time limit, while excluding such a time limit by the undesired effects of radiation caused by the undesirable degradation of organic matter in the region along the surface of said material, and in the case of fibrous material which is continuous moves along a production line compatible with speed lines, and that the duration (t) of irradiation of a given surface unit of said material is kept within said time limit.

Method according to claim 1, characterized in that said intensity level (1, ^) on the surface of said mineral wool material exceeds 500 mW / cm ² , preferably exceeds 1 W / cm ² and in particular exceeds 2 W / cm ² .

A method according to claim 1 or 2, characterized in that the wavelength of the ultraviolet radiation used exceeds 250 nm and preferably 310 nm.

A method according to any one of claims 1 to 3, characterized in that the irradiation duration (t) of said surface unit is less than 10 s, preferably less than 1 s and especially less than 0.5 s.

Method according to any one of claims 1 to 4, characterized in that the surface of said mineral wool material is cooled before irradiation.

Process according to any one of claims 1 to 5, characterized in that the proportion of oxygen contained in the atmosphere inside said mineral wool material is reduced to less than 10%, preferably less than 5% and especially less than 1 %.

A method according to any one of claims 1 to 6, characterized in that both major surfaces of said material are irradiated.

Method according to claim 7, characterized in that both sides are irradiated simultaneously.

A method according to claim 7 or 8, characterized in that a low polymerization region is provided in the central region of said material.

A process according to any one of claims 1 to 9, characterized in that a mixture of substances comprising epoxyacrylate is used as a prepolymer for forming the binder.

11. A device for polymerizing a substance in fibrous materials, such as, in particular, a binder in mineral wool material for isohalation purposes, comprising at least one ultraviolet radiation source (10), characterized in that the means (12) for focusing the ultraviolet radiation in at least one focused beam (18) of small width (b).

Device according to claim 11, characterized in that the focused beam (18) is shaped in a linear manner and is preferably held stationary.

Apparatus according to claim 11, characterized in that said focused bundle (18) has the form of a point that moves rapidly along said material (16) from mineral wool from one side to the other so that it preferably irradiates its entire surface.

Apparatus according to any one of claims 11 to 13, characterized in that said focused bundle (18) has a focal point (14) located within said mineral wool material (16) to be treated.

Device according to any one of claims 11 to 14, characterized in that the sources (10) of the ultraviolet radiation are arranged on either side of the larger surfaces of said mineral wool material (16).