SIZING COMPOSITION FOR MINERAL FIBERS AND RESULTING PRODUCTS

Abstract

The present invention relates to a sizing composition for mineral fibers, especially glass fibers or rock fibers, containing a liquid phenolic resin having a free formaldehyde content, expressed with respect to the total weight of liquid, of 0.1% or less and an extender.

Preferably, the liquid phenolic resin is mainly composed of phenol-formaldehyde and phenol-formaldehyde-amine condensates and has a water dilutability, at 20° C., at least equal to 1000%.

Another subject of the present invention is the insulating products based on mineral fibers treated by said sizing composition.

Claims

1. A sizing composition for mineral fibers, especially glass fibers or rock fibers, containing a liquid phenolic resin having a free formaldehyde content, expressed with respect to the total weight of liquid, of 0.1% or less and an extender.

Description

EXAMPLE 1

[0062] Introduced into a 2-liter reactor topped with a condenser and equipped with a stirring system were 378 g of phenol (4 mol) and 809 g of formaldehyde (10 mol) as a 37% aqueous solution (formaldehyde/phenol molar ratio equal to 2.5) and the mixture was heated at 45° C. with stirring.

[0063] 52.7 g of sodium hydroxide as a 50% aqueous solution (i.e. 7% by weight relative to the phenol) were regularly added over 30 minutes, the temperature was then progressively raised to 70° C. over 30 minutes, and this temperature was maintained for 80 minutes so as to reach a degree of phenol conversion equal to 93%.

[0064] Next, the temperature was reduced to 60° C. over 30 minutes and at the same time 75.3 g of monoethanolamine (1.2 mol) were introduced in a regular manner into the reaction mixture. The temperature was maintained at 60° C. for 15 minutes, the mixture was cooled down to about 25° C. over 30 minutes, and sulfamic acid as a 15% solution was added over 60 minutes until the pH was equal to 5.0.

[0065] The resin obtained had the appearance of a clear aqueous composition: it had a free formaldehyde content equal to 0.05%, a free phenol content equal to 0.2% (the contents being expressed with respect to the total weight of liquid) and a dilutability greater than 2000%.

[0066] The solids content of the liquid resin, by weight, was adjusted to 50% with water, and urea (20 parts by weight per 80 parts by dry weight of the liquid resin) was added.

[0067] A sizing composition was prepared by mixing 100 parts by dry weight of the aforementioned mixture of resin and urea, 7 parts by weight of molasses, 3 parts of ammonium sulfate, 1 part of silane (Silquest® A-1100 sold by OSI) and 8 parts of a mineral oil.

[0068] This sizing composition was used to fabricate an insulating product based on mineral wool. Conventionally, the sizing composition was sprayed onto glass fibers at the outlet from the fiberizing device in an amount of 4.5% by dry weight of size relative to the weight of the fibers. The sized fibers were collected on a belt conveyor where they formed a glass wool blanket, which was then subjected to a heat treatment in an oven in order to obtain a minimum temperature of 200° C. in the middle of the product.

[0069] The final insulating product had a nominal thickness of 200 mm and a nominal density of 11 kg/m.sup.3. It had mechanical properties in terms of tensile strength, thickness recovery and water absorption capacity that were identical to those of a product fabricated under the same conditions with a control sizing composition that did not contain an extender.

EXAMPLE 2

[0070] A liquid resin was prepared under the conditions from example 1.

[0071] A mixture containing 80 parts by dry weight of the liquid resin and parts by weight of urea was prepared.

[0072] A sizing composition was prepared by mixing 100 parts (by dry weight) of the aforementioned mixture of resin and urea, 5 parts by weight of a dextrin derived from corn starch, 3 parts of ammonium sulfate, 0.75 part of silane (Silquest® A-1100 sold by OSI) and 9.5 parts of a mineral oil.

[0073] The dextrin derived from corn starch had a weight-average molecular weight equal to 3510 and a dextrose equivalent (DE) equal to 30 (Roclys® C30725 sold by Roquette Freres; example 2a) or a weight-average molecular weight equal to 1850 and a dextrose equivalent (DE) equal to 30 (Tackidex® 30L75 sold by Roquette Freres; example 2b).

[0074] Conventionally, the dextrose equivalent DE is defined by the following equation:

[00001]$\mathrm{DE}=100\times \left(\frac{\mathrm{number}.Math..Math.\mathrm{of}.Math..Math.\mathrm{glycoside}.Math..Math.\mathrm{bonds}.Math..Math.\mathrm{broken}}{\mathrm{number}.Math..Math.\mathrm{of}.Math..Math.\mathrm{glycoside}.Math..Math.\mathrm{bonds}.Math..Math.\mathrm{in}.Math..Math.\mathrm{the}.Math..Math.\mathrm{initial}.Math..Math.\mathrm{starch}}\right)$

[0075] This sizing composition was used under the conditions of example 1 to fabricate an insulating product based on mineral wool having a nominal thickness of 80 mm and a nominal density of 11 kg/m.sup.3.

[0076] Also fabricated under the same conditions was an insulating product (Reference) in which the sizing composition did not contain an extender.

[0077] The following parameters were measured on the insulating products obtained:

[0078] the thickness recovery after 24 hours under compression with a compression ratio (defined as being the ratio of the nominal thickness to the thickness under compress) equal to 5/1. The thickness recovery is the ratio of the thickness measured to the nominal thickness, expressed in %; it makes it possible to evaluate the good dimensional behavior of the product; and

[0079] the tensile strength according to the ASTM C 686-71T standard on a specimen cut from the insulating product by stamping. The specimen had the shape of a torus having a length of 122 mm, a width of 46 mm, a radius of curvature of the cut at the outer edge equal to 38 mm and a radius of curvature of the cut at the inner edge equal to 12.5 mm.

[0080] The specimen was placed between two cylindrical mandrels of a test machine, one of which was mobile and moved at a constant speed. The breaking force F (in grams Force, gF) of the specimen was measured and the tensile strength was calculated from the ratio of the breaking force F to the mass of the specimen, expressed in gF/g.

[0081] The tensile strength was measured after the fabrication (TS fab.) and after an accelerated ageing in an autoclave at a temperature of 105° C. under 100% relative humidity for 15 minutes (TS15).

[0082] The measurements are collated in table 1.

EXAMPLE 3

[0083] A sizing composition was prepared under the conditions of example 2 but modified in that the dextrin derived from a corn starch was replaced by a soybean protein hydrolyzate (Soyad® 12UT sold by Hercules).

[0084] The sizing composition was used to fabricate an insulating product based on mineral wool under the same conditions as example 2.

[0085] The thickness recovery and tensile strength measurements are given in table 1.

TABLE-US-00001 TABLE 1 Ex. 2a Ex. 2b Ex. 3 Reference Thickness recovery (%) 151 151 150 149 Tensile strength (gF/g) TS fab. 337 327 360 297 TS15 319 318 347 257 loss (%) 5.3 2.7 3.6 13.4

[0086] The presence of an extender in examples 2 and 3 improves the tensile strength of the products and makes it possible to retain a thickness recovery comparable to that of the reference product without extender.