Sizing composition for fibers, in particular mineral fibers, comprising a non-reducing sugar and an inorganic acid ammonium salt, and resulting products

Abstract

A formaldehyde-free sizing composition for products based on fibers, in particular mineral fibers, such as fibers of glass or of rock, includes at least one non-reducing sugar, and at least one inorganic acid ammonium salt, preferably chosen from ammonium sulfates, phosphates, nitrates and carbonates. Another subject matter of the present invention is the products thus obtained, in particular thermal and/or acoustic insulators based on mineral wool and veils of nonwoven mineral fibers, and their process of manufacture.

Claims

1. An aqueous formaldehyde-free sizing composition comprising: sucrose; and ammonium sulfate; wherein the ammonium sulfate is present in a range from 3% to 20% by weight of sucrose and ammonium sulfate; and further comprising one or more additives in an amount from 0 to 2 parts of silane, 4 to 15 parts of mineral oil, 0 to 20 parts of glycerol, 0 to 5 parts of a silicone, and 0 to 30 parts of an extender, wherein the amount of each of the one or more additives is calculated on the basis of 100 parts by weight of sucrose and ammonium sulfate.

2. The composition of claimed 1, wherein the ammononium sulfate is present in a range from 5 to 15% by weight of sucrose and ammonium sulfate.

3. The composition of claim 1, wherein the one or more additives comprise from 0 to 10 parts of glycerol.

4. The composition of claim 1, wherein the sizing composition is devoid of organic polycarboxylic acid.

5. A product based on mineral fibers and/or organic fibers, the mineral fibers and/or organic fibers being sized using an aqueous formaldehyde-free sizing composition comprising: sucrose; and ammonium sulfate; wherein the ammonium sulfate is present in a range from 3% to 20% by weight of sucrose and ammonium sulfate.

6. The product of claim 5, wherein the product is a veil that includes mineral fibers.

7. The product of claim 5, wherein the product is an acoustic and/or thermal insulating product.

8. The product of claim 5, wherein the mineral fibers comprise glass wool or rock wool.

9. The product of claim 8, wherein the glass wool is made of E, C, R or AR (alkali-resistant) glass, and the rock wool is made from basalt, or the mineral fibers comprise more than 96% by weight of silica, or the mineral fibers are ceramic fibers based on at least one oxide, nitride, or carbide of a metal or a semimetal.

10. The product of claim 5, wherein the organic fibers are synthetic or natural fibers.

11. The product of claim 10, wherein the synthetic fibers are based on polyethylene or polypropylene.

12. The product of claim 5, wherein the sizing composition further comprises one or more additives in an amount from 0 to 2 parts of silane, 4 to 15 parts of mineral oil, 0 to 20 parts of glycerol, 0 to 5 parts of a silicone, and 0 to 30 parts of an extender, wherein the amount of each of the one or more additives is calculated on the basis of 100 parts by weight of sucrose and ammonium sulfate.

13. The product of claim 12, wherein the one or more additives comprise from 0 to 10 parts of glycerol.

14. The product of claim 5, wherein the ammonium sulfate is present in a range from 5 to 15% by weight of sucrose and ammonium sulfate.

15. The product of claim 5, wherein the sizing composition is devoid of organic polycarboxylic acid.

16. A process for the manufacture of a product, according to which mineral fibers and/or organic fibers is manufactured, the process comprising applying a sizing composition to said mineral fibers and/or organic fibers; and treating said mineral fibers and/or organic fibers at a temperature which makes possible the crosslinking of the size and the formation of an infusible binder, wherein the sizing composition comprises an aqueous formaldehyde-free sizing comprising: sucrose; and ammonium sulfate; wherein the ammonium sulfate is present in a range from 3% to 20% by weight of sucrose and ammonium sulfate.

17. The process of claim 16, wherein the sizing composition further comprises one or more additives in an amount from 0 to 2 parts of silane, 4 to 15 parts of mineral oil, 0 to 20 parts of glycerol, 0 to 5 parts of a silicone, and 0 to 30 parts of an extender, wherein the amount of each of the one or more additives is calculated on the basis of 100 parts by weight of sucrose and ammonium sulfate.

18. The process of claim 17, wherein the one or more additives comprise from 0 to 10 parts of glycerol.

19. The process of claim 16, wherein the mineral fibers comprise glass wool or rock wool.

20. The process of claim 19, wherein the glass wool is made of E, C, R or AR (alkali-resistant) glass, and the rock wool is made of basalt fibers including more than 96% by weight of silica.

21. The process of claim 16, wherein the ammonium sulfate is present in a range from 5 to 15% by weight of sucrose and ammonium sulfate.

22. The process of claim 16, wherein the sizing composition is devoid of organic polycarboxylic acid.

23. The process of claim 16, wherein the product is an acoustic and/or thermal insulating product.

24. The process of claim 6, wherein the product is a veil that includes mineral fibers.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 shows a curve of variation in the modulus of elasticity E (in MPa) as a function of the temperature (in C.).

DETAILED DESCRIPTION

(2) The expression non-reducing sugar should be understood in the conventional sense, namely that it relates to a sugar composed of several saccharide units, the carbon 1 of which carrying the hemiacetal OH group is the participant in a bond.

(3) The non-reducing sugar in accordance with the present invention is a non-reducing oligosaccharide including at most 10 saccharide units.

(4) Mention may be made, as examples of such non-reducing sugars, of disaccharides, such as trehalose, isotrehaloses, sucrose and isosucroses, trisaccharides, such as melezitose, gentianose, raffinose, erlose and umbelliferose, tetrasaccharides, such as stachyose, and pentasaccharides, such as verbascose.

(5) Preference is given to sucrose and trehalose and better still to sucrose.

(6) The inorganic acid ammonium salt reacts with the non-reducing sugar under the effect of the heat to form a polymeric network constituting the final binder. The polymeric network thus formed makes it possible to establish bonds between the mineral fibers, in particular at the junction points of the fibers in mineral wool, which confers, on the final product, a certain elasticity capable of providing good thickness recovery after the product has been unpacked.

(7) The inorganic acid ammonium salt is chosen from ammonium sulfates, in particular ammonium hydrogensulfate NH.sub.4HSO.sub.4 and ammonium sulfate (NH.sub.4).sub.2SO.sub.4, ammonium phosphates, in particular monoammonium phosphate NH.sub.4H.sub.2PO.sub.4, diammonium phosphate (NH.sub.4).sub.2HPO.sub.4 and ammonium phosphate (NH.sub.4).sub.3PO.sub.4, ammonium nitrates and ammonium carbonates, in particular ammonium bicarbonate NH.sub.4HCO.sub.3 and ammonium carbonate (NH.sub.4).sub.2CO.sub.3.

(8) The inorganic acid ammonium salt is preferably chosen from sulfates and phosphates, advantageously sulfates.

(9) In the sizing composition, the inorganic acid ammonium salt represents from 1 to 30% by weight of the total weight of the mixture composed of the non-reducing sugar and the inorganic acid ammonium salt, preferably from 3 to 20% and advantageously from 5 to 15%.

(10) The sizing composition does not comprise any organic polycarboxylic acid with a molar mass of less than 1000, and is generally totally devoid of organic polycarboxylic acid.

(11) The sizing composition can comprise, in addition to the compounds mentioned, the conventional additives below in the following proportions, calculated on the basis of 100 parts by weight of non-reducing sugar and of inorganic acid ammonium salt: from 0 to 2 parts of silane, in particular an aminosilane, from 0 to 20 parts of oil, preferably from 4 to 15 parts, from 0 to 20 parts of glycerol, preferably from 0 to 10 parts, from 0 to 5 parts of a silicone, from 0 to 30 parts of an extender.

(12) The role of the additives is known and is briefly restated: the silane is an agent for coupling between the fibers and the binder, and also acts as antiaging agent; the oils are dust-preventing and hydrophobic agents; the glycerol acts as plasticizer and makes it possible to prevent pregelling of the sizing composition; the silicone is a hydrophobic agent having the role of reducing the absorption of water by the insulating product; the extender is an organic or inorganic filler, soluble or dispersible in the sizing composition, which makes it possible in particular to reduce the cost of the sizing composition.

(13) The sizing composition exhibits a pH which varies according to the nature of the inorganic acid ammonium salt used, generally from 6 to 9, advantageously from 7 to 8.

(14) The sizing composition according to the invention is intended to be applied to fibers which can be mineral or organic, or else to a mixture of mineral and organic fibers.

(15) As already indicated, the mineral fibers can be glass fibers, in particular of E, C, R or AR (alkali-resistant) glass, or rock fibers, in particular basalt (or wollastonite). These fibers can also be fibers including more than 96% by weight of silica and ceramic fibers based on at least one oxide, nitride or carbide of metal or semimetal, or on a mixture of these compounds, in particular on at least one oxide, nitride or carbide of aluminum, zirconium, titanium, boron or yttrium.

(16) The organic fibers can be synthetic fibers or natural fibers.

(17) Mention may be made, as examples of synthetic fibers, of fibers based on an olefin, such as polyethylene and polypropylene, on a polyalkylene terephthalate, such as polyethylene terephthalate, or on a polyester.

(18) Mention may be made, as examples of natural fibers, of plant fibers, in particular fibers of wood, cellulose, cotton, coconut, sisal, hemp or flax, and animal fibers, in particular wool.

(19) As already mentioned, the sizing composition is more particularly used as sizing composition for thermal and/or acoustic insulating products based on mineral wool.

(20) Conventionally, the sizing composition is applied to the mineral fibers at the outlet of the fiber-forming device and before they are collected on the receiving member in the form of a web of fibers which is subsequently treated at a temperature which makes possible the crosslinking of the size and the formation of an infusible binder. The crosslinking of the size according to the invention takes place at a temperature of the order of from 100 to 200 C., generally at a temperature comparable to that of a conventional formaldehyde-phenol resin, in particular of greater than or equal to 110 C., preferably of less than or equal to 170 C.

(21) The products based on fibers sized using the composition, in particular the acoustic and/or thermal insulating products obtained from these sized fibers, also constitute a subject matter of the present invention.

(22) These products are generally provided in the form of a mat, a felt, panels, blocks, shells or other molded shapes based on mineral wool, of glass or of rock.

(23) The sizing composition can also be used to manufacture coated or impregnated fabrics and veils (also known as nonwovens), in particular based on mineral fibers, such as glass or rock fibers.

(24) Veils of mineral fibers are used in particular as surface coating for thermal and/or acoustic insulating products based on mineral wool or on a foam.

(25) Another subject matter of the invention is a process for the manufacture of a thermal and/or acoustic insulating product based on mineral wool or of a veil of mineral fibers, according to which the mineral wool or the mineral fibers is/are manufactured, a composition according to the invention is applied to said wool or said fibers and said wool or said fibers is/are treated at a temperature which makes possible the crosslinking of the size and the formation of an infusible binder, for example under the thermal conditions described above.

(26) The size can be applied by any appropriate means, for example by projection, spraying, atomization, coating or impregnation.

(27) The following examples make it possible to illustrate the invention without, however, limiting it.

(28) In these examples, the following are measured: the crosslinking start temperature (T.sub.C) and the crosslinking rate (R) by the Dynamic Mechanical Analysis (DMA) method, which makes it possible to characterize the viscoelastic behavior of a polymeric material. The procedure is as follows: a sample of Whatman paper is impregnated with the sizing composition (content of organic solids of the order of 40%) and is then fixed horizontally between two jaws. An oscillating component equipped with a device for measuring the stress as a function of the strain applied is positioned on the upper face of the sample. The device makes it possible to calculate the modulus of elasticity E. The sample is heated to a temperature varying from 20 to 250 C. at the rate of 4 C./min. The curve of variation in the modulus of elasticity E (in MPa) as a function of the temperature (in C.) is plotted from the measurements, the general appearance of the curve being given in FIG. 1. The temperature value, in C., for the start of crosslinking (T.sub.C) and the slope corresponding to the crosslinking rate, in MPa/ C., are determined on the curve. the viscosity, expressed in mPa.Math.s, using a rheometer of plate/plate rotational type with shearing of 100 s.sup.1 at 25 C. The sample has a solids content of 30% by weight. the contact angle of the sizing composition, comprising 30% by weight of solids, on a glass substrate. the breaking stress of a veil sample of 5 cm21 cm attached at one end to a tensile testing device and subjected to a continuous elongation of 40 mm/minute. The breaking stress is expressed in N/5 cm.

(29) The breaking stress is measured after manufacturing (initial) and after the sample has been treated under accelerated aging conditions in water at 80 C. for 10 minutes. The result is expressed by the percentage of retention, which is equal to:
(breaking stress after treatment/initial breaking stress)100. the tensile strength according to the standard ASTM C 686-71T on a sample cut out by stamping from the insulating product. The sample has the shape of a torus with a length of 122 mm, a width of 46 mm, a radius of curvature of the cut-out of the outer edge equal to 38 mm and a radius of curvature of the cut-out of the inner edge equal to 12.5 mm.

(30) The sample is positioned between two cylindrical mandrels of a test machine, one of which is movable and is moved at a constant rate. The breaking force F (in newtons) of the sample is measured and the tensile strength TS, defined by the ratio of the breaking force F to the weight of the sample, is calculated.

(31) The tensile strength is measured after manufacture (initial tensile strength) and after accelerated aging in an autoclave at a temperature of 105 C. under 100% relative humidity for 15 minutes (TS 15). the initial thickness of the insulating product and the thickness after compressing for 1 hour and 24 hours with a degree of compression (defined as being the ratio of the nominal thickness to the thickness under compression) equal to 4.8/1. The thickness measurements make it possible to evaluate the good dimensional behavior of the product. the thermal conductivity coefficient according to the standard EN 13162, expressed in W/(m K).

EXAMPLES 1 TO 20

(32) a) A first series of sizing compositions is prepared, which compositions comprise the constituents appearing in table 1, expressed as parts by weight.

(33) The sizing compositions are prepared by successively introducing, into a vessel containing water, the non-reducing or reducing sugar and the inorganic acid ammonium salt with stirring until the constituents have completely dissolved.

(34) The sizing compositions of examples 1 and 4 exhibit a greater crosslinking rate than comparative examples 7 and 8 respectively.

(35) Examples 1 to 6 exhibit low viscosity and contact angle values, comparable to comparative examples 7 and 8, which makes possible good application to mineral fibers, in particular by spraying.

(36) b) A second series of sizing compositions is prepared, which compositions comprise the constituents appearing in table 2, expressed as parts by weight.

(37) The sizing compositions are prepared under the conditions set out for the first series.

(38) Test 1

(39) A veil of glass fibers (Whatman GF/A, 50 g/m.sup.2; sold by Whatman) is immersed in the sizing composition (13% of solid matter) for 2 minutes and then the excess size is removed by suction. The veil is subsequently treated in an oven at 200 C. for 135 seconds. In the end, the veil comprises 45% by weight of crosslinked binder. The values of the tensile strength and of the percentage of retention are given in table 2.

(40) Test 2

(41) A veil of glass fibers (Whatman GF/A, 50 g/m.sup.2; sold by Whatman) is immersed in the sizing composition (13% of solid matter) for 2 minutes and then the excess size is removed by suction. The veil is subsequently treated in an oven at 200 C. for 5 minutes. In the end, the veil comprises 45% by weight of crosslinked binder.

(42) The veil is immersed in water at 60 C. for 3 hours and is then dried in an oven at 60 C. for 1 hour. The portion of water-insoluble crosslinked binder remaining on the veil (as %) is measured by weighing before and after immersion in the water. The results appear in table 2.

(43) Examples 3, 2 and 9, on the one hand, and 6 and 5, on the other hand, have a higher initial tensile strength than the corresponding comparative examples 11 to 14, and 17 and 18.

(44) Examples 3, 2, 9 and 10, comprising ammonium sulfate, have a higher percentage of retention than comparative examples 11 to 14. Examples 15 and 16, comprising a higher proportion of diammonium sulfate, have a greater wet aging strength than comparative examples 19 and 20.

(45) The proportion of binder remaining on the filter after treatment in the water is greater in the examples according to the invention (3, 2, 9 and 10, and 6, 5, 15 and 16) than in the respective comparative examples (11 to 14 and 17 to 20).

(46) Tests 1 and 2 demonstrate that the sizing composition according to the invention has the capability of efficiently binding the fibers of a veil under conditions of accelerated aging in a humid environment. The application of the sizing composition is not limited to veils and can be extended to the other fibrous products mentioned above, in particular to fabrics and to products where the fibers are provided in the form of mineral wool for applications as thermal and/or acoustic insulating products.

EXAMPLES 21 AND 22

(47) These examples illustrate the manufacture of insulating products on an industrial scale line.

(48) Use is made of the sizing compositions of examples 1 and 7 (comparative), to which the following additives are added, per 100 parts by weight of sugar and ammonium sulfate: 1 part of -aminopropyltriethoxysilane and 8 parts of a mineral oil. These sizing compositions constitute examples 21 and 22 (comparative) respectively.

(49) Glass wool is manufactured on a pilot scale line by the internal centrifugation technique in which the molten glass composition is converted into fibers by means of a tool, referred to as centrifuging disk, comprising a basket forming a chamber for receiving the molten composition and a peripheral band pierced by a multitude of orifices: the disk is rotated about its vertically positioned axis of symmetry, the composition is ejected through the orifices under the effect of the centrifugal force and the material escaping from the orifices is drawn into fibers with the assistance of a drawing gas stream.

(50) Conventionally, a size spraying ring is positioned beneath the fiberizing disk so as to uniformly distribute the sizing composition over the glass wool which has just been formed.

(51) The mineral wool, thus sized, is collected on a belt conveyor with a width of 2.4 m equipped with internal extraction boxes which hold the mineral wool in the form of a web at the surface of the conveyor. The web passes continuously through an oven maintained at 270 C., where the constituents of the size polymerize to form a binder. The final insulating product has a nominal density of 17.5 kg/m.sup.3.

(52) The insulating products exhibit the following properties:

(53) TABLE-US-00001 Ex. 21 Ex. 22 (comp.) Tensile strength (N) initial 4.5 4.2 after aging (TS 15) 4.3 3.8 loss (%) 4 10 Thickness (mm) after 1 hour 106 102 after 24 hours 104 100 Loss on ignition (%) 6.0 6.0 (W/(m K)) 0.035 0.035

(54) The insulating product according to example 21 exhibits a higher initial tensile strength than that of comparative example 22. The tensile strength after aging of example 21 is also greater, the loss in tensile strength being 4% instead of 10% for comparative example 22.

(55) In addition, the insulating product according to example 21 has an initial thickness which is slightly enhanced with respect to comparative example 22.

(56) TABLE-US-00002 TABLE 1 Example 7 8 1 2 3 4 5 6 (Comp.) (Comp.) Sizing composition Sucrose 85 90 95 85 90 95 Glucose 85 85 Ammonium sulfate 15 10 5 15 Diammonium phosphate 15 10 5 15 Properties Crosslinking start temp. T.sub.C ( C.) 137 141 146 144 149 158 140 132 Rate (R) (MPa/ C.) 86.7 64.2 58.8 49.3 51.7 30.6 54.5 26.7 Viscosity (mPa .Math. s) 5.4 5.5 5.4 5.4 5.5 5.5 5.4 5.4 Contact angle () 17 18 20 17 18 17 19 18 pH.sup.(1) 7.2 7.2 7.3 8.0 7.9 7.8 7.5 7.1 .sup.(1)solids content: 30%

(57) TABLE-US-00003 TABLE 2 Example 11 12 13 14 3 2 9 10 (Comp.) (Comp.) (Comp.) (Comp.) Binder composition Sucrose 95 90 83 77 Glucose 95 90 83 77 Ammonium sulfate 5 10 17 23 5 10 17 23 Diammonium phosphate Properties Tensile strength (N/cm) initial 104 120 130 109 100 96 111 115 % retention 22 46 65 66 9 30 52 61 Insoluble portion (%) 81.5 85.9 83.9 81.9 76.2 75.3 76.0 79.9 Example 17 18 19 20 6 5 15 16 (Comp.) (Comp.) (Comp.) (Comp.) Binder composition Sucrose 95 90 83 77 Glucose 95 90 83 77 Ammonium sulfate Diammonium phosphate 5 10 17 23 5 10 17 23 Properties Tensile strength (N/cm) initial 83 120 99 120 65 99 118 131 % retention 11 53 86 68 10 53 58 53 Insoluble portion (%) 87.6 97.9 95.3 93.7 86.7 91.6 91.9 85.6