Process for producing mineral wool

Abstract

The present invention relates to a process for producing insulating products based on mineral fibers, in particular on mineral wool, comprising providing a first binder composition containing (a) from 50% to 85% by weight of water, preferably from 70 to 82% of water (b) from 10% to 45% by weight, preferably 15 to 35% by weight of a saccharide component containing sucrose, (c) from 3% to 15% by weight, preferably from 5 to 12% by weight of one or more ammonium salts or primary amine salts of an acid, preparing a second binder composition comprising the dilution of the first aqueous binder composition with water to a solids content of between 3 and 7% by weight, applying the second binder composition to mineral fibers, forming an assembly of mineral fibers coated with the second binder composition, and heating the assembly of coated mineral fibers so as to form an assembly of mineral fibers bound by an insoluble binder,
said process being characterized in that the first aqueous binder composition has a pH of less than 5.5, in that the ammonium salt or primary amine salt is a salt of strong acid or a salt of an acid having a pKa of less than or equal to 2.2, and in that the first and second binder compositions are devoid of salts of weak acids having at least a pKa of between 2.5 and 6.9.

Claims

1. A process for producing insulating products based on mineral fibers, the process comprising: diluting a first binder composition with water, to obtain a second binder composition having a solids content of between 3 and 7% by weight, wherein the first binder composition comprises: (a) from 50% to 85% by weight of water; (b) from 10% to 45% by weight of a saccharide component comprising sucrose; and (c) from 3% to 15% by weight of one or more ammonium salts or primary amine salts of an acid; applying the second binder composition to mineral fibers; forming an assembly of mineral fibers coated with the second binder composition; and heating the assembly of coated mineral fibers so as to form an assembly of mineral fibers bound by an insoluble binder, wherein the first binder composition has a pH of less than 5.5, wherein the ammonium salt or primary amine salt is a salt of strong acid or a salt of an acid having a pKa of less than or equal to 2.2, and wherein the first and second binder compositions are devoid of salts of weak acids having at least a pKa of between 2.5 and 6.9.

2. The process as claimed in claim 1, wherein the saccharide component comprises at least 50% by weight of sucrose.

3. The process as claimed in claim 1, wherein a weight ratio of the saccharide component to the ammonium salt or primary amine salt is between 60/40 and 95/5.

4. The process as claimed in claim 1, wherein the primary amine is a primary diamine.

5. The process as claimed in claim 1, further comprising: adding one or more additives to the first binder composition to obtain the second binder composition.

6. The process as claimed in claim 5, wherein the additive is at least one selected from the group consisting of a coupling agent, a silicone, and a dust preventative.

7. The process as claimed in claim 1, wherein the process does not comprise adding a base to first binder composition to obtain the second binder composition.

8. The process as claimed in claim 1, wherein the second binder composition has a pH of less than 6.

9. The process as claimed in claim 1, wherein the first binder composition comprises: (a) from 70% to 82% by weight of water; (b) from 15% to 35% by weight of the saccharide component; and (c) from 5% to 12% by weight of the ammonium salts or the primary amine salts of an acid.

10. The process as claimed in claim 1, wherein the solid content of the second binder composition between 4 and 6% by weight.

11. The process as claimed in claim 1, wherein the saccharide component comprises at least 80% by weight of sucrose.

12. The process as claimed in claim 1, wherein the saccharide component comprises at least 95% by weight of sucrose.

13. The process as claimed in claim 1, wherein the weight ratio of the saccharide component to the ammonium salt or primary amine salt is between 65/35 and 90/10.

14. The process as claimed in claim 1, wherein the weight ratio of the saccharide component to the ammonium salt or primary amine salt is between 70/30 and 88/12.

Description

EXAMPLES

(1) Concentrated compositions of binder comprising the ingredients appearing in table 1 in amounts expressed as parts by weight of dry matter are prepared. The concentrated compositions have a content of dry matter of approximately 25%, that is to say they contain approximately 75% of water. The initial pH indicated in table 1 is the pH of these concentrated compositions.

(2) The binder compositions are prepared by introducing the constituents into a container containing water, with vigorous stirring until a homogeneous solution is formed. The initial pH indicated in table 1 is the pH of this homogeneous concentrated solution. These concentrated compositions are subsequently diluted with water to a dry matter content of 5% by weight. 8 parts of a mineral oil emulsion (dust-preventing additive), 0.5 part of aminosilane and 0.1 part of a silicone are also added thereto. It is checked that the pH of the diluted solutions is less than or equal to 6.0, and if necessary acidification is carried out by adding a strong acid. These diluted sizing compositions are used to form insulation products based on glass wool.

(3) Glass wool is produced by the internal centrifugation technique in which the molten glass composition is converted into fibers using a tool referred to as a centrifugation plate, comprising a basket forming the chamber for receiving the molten glass composition and a peripheral strip pierced with a multitude of holes: the plate turns about its vertically arranged axis of symmetry, the composition is ejected through the holes under the effect of the centrifugal force and the material escaping through the holes is stretched into fibers with the assistance of a stream of stretching gas. The thinness of the glass fibers, measured by the value of the micronaire thereof under the conditions described in patent application FR 2 840071, is equal to 15.8 l/min. There is a correspondence relationship between the micronaire value and the mean diameter of the fibers.

(4) A spraying ring comprising equidistant nozzles is placed below the fiberizing plate so as to regularly distribute the sizing composition over the glass wool fibers that have just been formed.

(5) The mineral wool thus sized is collected on a belt conveyor having a width of 2.40 m, fitted with internal suction chambers which hold the mineral wool in the form of a felt or a web on the surface of the conveyor. The conveyor subsequently passes into an oven where the reagents of the binder composition (sucrose+ammonium/primary amine salt) polymerize to form a set, non-tacky, binder. The insulating product obtained has a density equal to 27.0 kg/m.sup.3, a thickness of approximately 80 mm immediately after production and a loss on ignition of between approximately 3 and 5.0%.

(6) Table 1 below shows the chemical nature and the content by weight of the ingredients forming each sizing composition (A, B, C, D, E), the initial pH of the concentrated aqueous sizing composition having a content of dry matter of approximately 25% by weight, the loss on ignition of the final product, expressed as % by weight the tensile strength (in N/g) of the final product, determined in the manner described above.

(7) TABLE-US-00001 TABLE 1 Ingredients Initial pKa of Loss on Tensile Composition (parts by weight) pH the acid ignition (%) strength (N/g) A* Sucrose/ammonium 4.7 1.99 4.69 4.08 sulfate (85/15) B* Sucrose/HMDA/H.sub.3PO.sub.4 5.3 2.12 3.64 3.98 (67.9/11.9/20.2) C Sucrose/HMDA/H.sub.3PO.sub.4 9.1 2.12 3.93 3.16 (75.5/13.3/11.2) D Sucrose/HMDA/H.sub.3PO.sub.4 11.6 2.12 3.64 2.77 (80/14/6) E Sucrose/TPA/H3PO4 2.1 2.12 3.07 1.70 (79.9/14.1/6) F Sucrose/ammonium 8 4.76 Line Line acetate stoppage stoppage (85/15) *Compositions according to the invention; HDMA = hexamethylenediamine; TPA = tripentylamine

(8) Only the compositions A and B are compositions according to the invention, namely aqueous sizing compositions which contain sucrose and an ammonium salt (composition A) or a primary amine salt (composition B) of a strong acid (composition A) or of a weak acid having a pKa of less than 2.2, and which have an initial pH of less than 5.5.

(9) Compositions C and D are comparative compositions because their initial pH is too high (greater than 5.5).

(10) Composition E is a comparative composition because the amine is not a primary amine but a tertiary amine.

(11) Composition F is a comparative composition since acetic acid is a weak acid having too high a pKa (4.76). The stoppage of the mineral wool production line was caused by the very mediocre mechanical properties of the panel formed.