Process for the manufacture of an insulating product based on mineral fibres

1. A process for the manufacture of an insulating product based on mineral fibres bonded by an organic binder, comprising:

a. applying a sizing composition to the mineral fibres,

b. forming an assembly of the mineral fibres,

c. heating said assembly of mineral fibres until the sizing composition has cured,

wherein:

the sizing composition comprises the following constituents within the limits defined below, expressed as fractions by weight with respect to the total weight of the composition:

from 80% to 98% of water,

from 2% to 20% of water-soluble poly(furfuryl alcohol), which is obtained by polycondensation of furfuryl alcohol, and

less than 0.5% of furfuryl alcohol,

the mineral fibres are fibres of aluminosilicate glass comprising aluminium oxide, Al 2 O 3 , in a fraction by weight of between 14% and 28%,

wherein a sum of the fractions by weight of the poly(furfuryl alcohol) and of the water is at least 95%, and

wherein the sizing composition applied to the mineral fibres has a pH in a range from 5 to 8.

2. The process according to claim 1 , wherein the mineral fibres have a fraction by weight of SiO 2 of between 32% and 50%.

3. The process according to claim 1 , wherein a sum of the Al 2 O 3 and SiO 2 fractions by weight of the mineral fibres is between 46% and 78%.

4. The process according to claim 1 , wherein the mineral fibres have an Al 3+ /(Al 3+ +Si 4+ ) molar ratio of greater than 0.25.

5. The process according to claim 4 , wherein the mineral fibres have an Al 3+ /(Al 3+ +Si 4+ ) molar ratio of greater than 0.35.

6. The process according to claim 1 , wherein the mineral fibres additionally comprise the oxides CaO and MgO, a sum of the fractions by weight of the oxides being between 7% and 32%.

7. The process according to claim 1 , wherein the mineral fibres additionally comprise the oxides Na 2 O and K 2 O, a sum of the fractions by weight of the oxides being between 1% and 15%.

8. The process according to claim 1 , wherein the mineral fibres have a dissolution coefficient of greater than 100 ng·cm −2 ·h −1 , the dissolution coefficient being calculated from the amount of SiO 2 of the mineral fibres which is dissolved in a synthetic pulmonary fluid of pH 4.5, thermally regulated at 37° C., after 14 days.

9. The process according to claim 8 , wherein the dissolution coefficient is greater than 400 ng·cm −2 ·h −1 .

10. The process according to claim 1 , wherein a content of furfuryl alcohol of the sizing composition is less than 0.1%.

11. The process according to claim 1 , wherein said sizing composition additionally comprises one or more adjuvants chosen from coupling agents, dust-preventing agents, hydrophobic agents, retardants, antistatic agents, softening agents, conditioning agents, colouring agents or opacifying agents.

12. The process according to claim 11 , wherein a fraction by weight of adjuvants and additives of the solid part of the sizing composition does not exceed 25%.

13. The process according to claim 12 , wherein the fraction by weight of adjuvants and additives of the solid part of the sizing composition does not exceed 20%.

14. The process according to claim 1 , wherein the application of the sizing composition of stage a) to the mineral fibres is carried out by spraying by means of spray nozzles.

15. The process according to claim 1 , wherein stage c) comprises the heating of the assembly of mineral fibres at a temperature of between 100° C. and 250° C. for a period of time of between 1 minute and 10 minutes.

16. The process according to claim 15 , wherein the heating of the assembly of mineral fibres is in a thermally regulated atmosphere.

17. The process according to claim 1 , wherein a sum of the fractions by weight of the poly(furfuryl alcohol) and of the water is at least 98%.

18. The process according to claim 1 , wherein the pH is from 6.0 to 8.0.

19. The process according to claim 1 , wherein the pH is from 5.5 to 8.