Substrate for a support for bituminous membrane and method for the preparation thereof

Abstract

A substrate for a support for bituminous membranes, comprising two or more layers of fibers comprising a homogeneous mixture of organic fibers and inorganic fibers, between which there is interposed a reinforcing scrim, said fibers being oriented parallel to the longitudinal axis of the substrate and laid said by side and alternate.

Claims

1. A support substrate for roof covering waterproof bituminous membranes, wherein the substrate comprises at least two fiber layers arranged parallel above one another, wherein each fiber layer comprises a homogeneous mix of organic and inorganic fibers oriented parallel to a longitudinal direction of the substrate, wherein the mix comprises a weight percentage of organic fibers between 50% and 90% and the remainder is made of inorganic fibers, wherein a reinforcing scrim with longitudinal glass threads and transversal polyester threads is interposed between and placed in direct contact with the at least two parallel fiber layers, and wherein the fiber layers and the scrim are permeated with a consolidation organic fluid hydroentangling binder.

2. The substrate according to claim 1, wherein the mix comprises a weight percentage of organic fibers between 60% and 80% and the remainder being inorganic fibers.

3. The substrate according to claim 1, wherein the organic fiber is produced from spinnable polymers.

4. The substrate according to claim 1, wherein the substrate comprises between 5% and 15% by weight of the binder.

5. The substrate according to claim 1, wherein the organic fiber has a denier between 1.1 dtex and 17 dtex and a cutting length between 38 and 120 mm.

6. The substrate according to claim 1, wherein the inorganic fiber is glass fiber.

7. The substrate according to any claim 6, wherein the glass fiber has a denier between 1.1 dtex and 6.7 dtex and a cutting length between 25 and 80 mm.

8. The substrate according to claim 1, wherein the substrate has a breaking strength that is higher than 0.60 DaN/5 cm per g/m.sup.2 for a weight per unit area of substrate equal to or higher than 100 g/m.sup.2.

9. A method for producing a substrate (1) for a support for bituminous membranes according to claim 1, characterized in that it provides the mixing of organic (31) fibers and inorganic (32) fibers obtained through repeated opening and blending operations during the fiber preparation to the carding step, the combination of two or more fiber (3) layers obtained with said mixing dry-processed products by means of a card, the interposition between said layers of a reinforcing scrim (4), the consolidation of the substrate by means of high pressure water jets (hydroentangling), the drying and heat setting.

10. A method according to claim 9, characterized in that it provides a further consolidation step through the application of a binder.

11. A method according to claim 9, characterized in that during the hydroentangling step the substrate (1) is treated in one or more water jet beams, with a water pressure comprised between 50 and 350 Bar, preferably between 60 and 180 Bar.

12. A method according to claim 9, characterized in that the drying and heat setting is performed in a hot air furnace at a temperature comprised between 200 and 250 C., preferably between 220 and 240 C.

13. A method according to claim 9, characterized in that the heat setting is performed by means of calendering with rolls heated at a temperature between 190 and 250 C.

14. A method according to claim 9, characterized in that said inorganic fibers (32) are glass fibers.

15. The substrate according to claim 1, wherein the binder is acrylic, styrene-acrylic, styrene-butadiene, or vinyl, and is blended with natural binders that are derived from starches or vegetal cellulose.

16. The substrate according to claim 1, wherein the substrate comprises between 5% and 10% by weight of the binder.

17. The substrate according to claim 1, wherein the organic fiber has a denier between 2.8 dtex and 6.7 dtex and a cutting length between 50 and 100 mm.

18. The substrate according to claim 1, wherein the glass fiber has a denier between 1.7 dtex and 4.4 dtex and a cutting length between 30 and 50 mm.

19. The substrate according to claim 3, wherein the spinnable polymers are selected from the group consisting of polyamides, polyesters, and polymers with ether or ketone groups.

Description

EXAMPLE 1

(1) A substrate 1 of 106 g/m2 is made by mixing 70% by weight of polyester staple fiber with denier 4.4 dtex, length 76 mm, and 30% of glass staple fiber with denier 5 dtex and length 60 mm. The mixture is obtained by means of a filler, balance and card-opener system which allows achieving a high mixing homogeneity.

(2) The fiber has been pneumatically conveyed to a volumetric feeding system of a longitudinal drum carding machine which, at a speed of 90 m/min, has produced two separate films having the weight of 40 g/m2 each, deposited on two conveyors.

(3) Between the two films there is inserted a glass scrim 4 having a rectangular mesh 1.60.8 threads/cm of yarn 68 Tex and the composite, formed by the two films and the scrim interposed, is consolidated in a water jet needling machine, consisting of four hydroentangling units operated at a pressure of 150 Bar.

(4) The substrate 1 is dried and thermally fixed at 230 C. by means of a hot-air calendar and impregnated with a saturation via padding machine with a mixture of resin consisting of 50% styrene butadiene binder, Lutofan DS2380 produced by Basf, and 50% corn dextrin, Stabilys A022 produced by Roquette, dispersed in water with a solid residue of 10%.

(5) The substrate 1 is dried in a forced air-circulation furnace and the resin polymerized at 210 C.

(6) The thus obtained product is compared with the product made according to the prior art as follows.

(7) 120 g/m2 substrate made with spunbonded polyester, in two layers consolidated via mechanical needling, with interposed longitudinal reinforcing glass threads, denier 68 tex, placed at a distance of 8 mm.

(8) The composite substrate consolidated via mechanical needling with a density of 40 dots/cm2, thermally stabilized on a hot-air calendar at 230 C. and saturation impregnated with a mixture of resin consisting of 50% styrene butadiene binder, Lutofan DS2380 produced by Basf, and 50% corn dextrin, Stabilys A022 produced by Roquette, dispersed in water with a solid residue of 25%.

(9) The substrate is dried in a forced air-circulation furnace and the resin polymerized at 210 C.

(10) The comparison between the results of the force gauge assays, according to EN 29073-3, is reported in Table 1 below.

(11) TABLE-US-00001 TABLE 1 Comparison product 100 g/m2 according to the invention with product spun 120 g/m2 according to the prior art - Example 1 New product Prior art Spun Example 1 reinforced 100 g/m2 120 g/m2 Weight per MD g/m2 106 124 surface unit CD g/m2 106 125 Maximum load MD N/5 cm 315 449 CD N/5 cm 380 218 Specific load MD daN/5 cm/g/m2 0.30 0.36 CD 0.36 0.17 TOT 0.66 0.54 Elongation at MD % 15 18 break CD % 17 22 Isotropy 0.83 2.06

EXAMPLE 2

(12) A substrate 1 of 85 g/m2 is made by mixing 70% by weight of polyester staple fiber, with denier 4.4 dtex and length 76 mm, and 30% of glass staple fiber, with denier 5 dtex and length 60 mm. The mixture is obtained by means of a filler, balance, card-opener and mixer system which allows achieving a high mixing homogeneity.

(13) The fiber is pneumatically conveyed to a volumetric feeding system of a longitudinal drum carding machine which, at a speed of 90 m/min, has produced two separate films of 30 g/m2 each, deposited on two conveyors.

(14) Between the two films there is inserted a glass scrim 4 having a rectangular mesh 1.60.8 threads/cm of yarn 34 Tex and the composite, formed by the two films and the scrim interposed, is consolidated in a water jet needling machine, consisting of a wetting unit and 4 hydroentangling units operated at a pressure of 50 to 150 Bar.

(15) The substrate 1 is dried and thermally fixed at 230 C. by means of a hot-air furnace and impregnated by saturation via padding machine with a mixture of resin consisting of 50% styrene butadiene binder, Lutofan DS2380 produced by Basf, and 50% corn dextrin, Stabilys A022 produced by Roquette, dispersed in water with a solid residue of 10%.

(16) The substrate 1 is dried in a forced air-circulation furnace and the resin polymerized at 210 C.

(17) The resulting product is compared with the product made according to the prior art, produced as described hereinafter.

(18) 120 g/m2 Substrate made with 100% staple polyester, with denier 4.4 dtex and length 76 mm, in two layers consolidated via needling and with interposed longitudinal reinforcing glass threads, with denier 68 tex, placed at a distance of 8 mm.

(19) The composite substrate, consisting of two layers and with interposed reinforcing glass threads, is consolidated via further mechanical needling with a density of 80 dots/cm2, and impregnated with a saturation via padding machine with a mixture of resin consisting of 50% styrene butadiene binder, Lutofan DS2380 produced by Basf, and 50% corn dextrin, Stabilys A022 produced by Roquette, dispersed in water with a solid residue of 25%.

(20) The substrate is dried in a forced air-circulation furnace and the resin polymerized at 210 C.

(21) The comparison between the results of the force gauge assays is reported in Table 2 below.

(22) TABLE-US-00002 TABLE 2 Comparison product 90 g/m2 according to the invention with product staple 120 g/m2 according to the prior art - Example 2 New product Prior art Example 2 Reinforced 90 g/m2 staple 120 g/m2 Weight per MD g/m2 86 120 surface unit CD g/m2 85 120 Maximum load MD (N/5 cm) 288 296 CD (N/5 cm) 115 178 Specific load MD daN/5 cm/g/m2 0.33 0.25 CD 0.14 0.15 TOT 0.47 0.40 Elongation at MD % 11 19 break CD % 19 27 Isotropy 2.50 1.66

EXAMPLE 3

(23) A substrate 1 of 140 g/m2 is made by mixing 70% by weight of polyester staple fiber, with denier 4.4 dtex and length 76 mm, and 30% of glass staple fiber, with denier 5 dtex and length 60 mm. The mixture is obtained by means of a filler, balance, card-opener and mixer system which allows achieving a high mixing homogeneity.

(24) The fiber 3 has been pneumatically conveyed to a volumetric feeding system of a longitudinal drum carding machine which, at a speed of 90 m/min, has produced two separate films of 50 g/m2 each, deposited on two conveyors.

(25) Between the two films there is inserted a glass scrim 4 having a rectangular mesh 22 threads/cm of yarn 68 Tex and the composite, formed by the two films and the scrim interposed, is consolidated in a water jet needling machine, consisting of a wetting unit and four hydroentangling units operated at a pressure of 50 to 150 Bar.

(26) The substrate 1 is dried and thermally fixed at 230 C. by means of a hot-air furnace and impregnated with a saturation via padding machine with a mixture of resin consisting of 100% corn dextrin, Stabilys D033 produced by Roquette, dispersed in water with a solid residue of 10%.

(27) The substrate 1 is dried in a forced air-circulation furnace and the resin polymerized at 210 C.

(28) The thus obtained product is compared with the product made according to the prior art, produced as described hereinafter.

(29) 200 g/m2 substrate made with 100% staple polyester, with denier 4.4 dtex and length 76 mm, in two layers consolidated via needling and with interposed longitudinal reinforcing glass threads, with denier 68 tex, placed at a distance of 8 mm.

(30) The composite substrate, consisting of two layers and with interposed reinforcing glass threads, is consolidated via further mechanical needling with a density of 80 dots/cm2, and impregnated with a saturation via padding machine with a mixture of resin consisting of 70% styrene butadiene binder, Lutofan DS2380 produced by Basf, and 50% corn dextrin, Stabilys A022 produced by Roquette, dispersed in water with a solid residue of 25%.

(31) The substrate is dried in a forced air-circulation furnace and the resin polymerized at 210 C.

(32) The comparison between the results of the force gauge assays is reported in Table 3 below.

(33) The specimens of the substrate of the new product having size 5 cm30 cm are taken according to Standard EN 29073-3, in the longitudinal direction.

(34) The numbered specimens are weighted with a mg precision balance and the weight is noted down as P.sub.i.

(35) The specimens are later treated in a muffle furnace at 450 C. for 30 minutes until complete elimination of the organic part.

(36) The residual ashes, after dryer cooling, are weighted and the value noted down as P.sub.v (P.sub.v=weight of glass staple+weight of scrim).

(37) The weight of the fibrous part P.sub.f of the substrate is calculated with the following formula:
P.sub.f=0.9*(P.sub.iP.sub.r)

(38) Where P.sub.r is the weight of the reinforcing scrim contained in the surface of the specimen and 0.9 a reduction coefficient to account for any losses.

(39) The best results are achieved when the distribution of the fibers is homogeneous and the ratio (P.sub.vP.sub.r)/P.sub.f is comprised, in the case of the example under examination, between 0.27 and 0.33, that is between 90% and 110% of the proportion of glass fibers in the parent mixture (30%).

(40) Table 4 shows the experimental results of the assay.

(41) For each of the specimens:

(42) P.sub.i=initial weight of the specimen

(43) P.sub.v=weight of the glass component

(44) P.sub.r=weight of the reinforcing scrim

(45) P.sub.f=weight of the fibrous component (organic fibers+glass fibers)

(46) (P.sub.vP.sub.r)/P.sub.f=ratio between the weight of the component of glass fibers and the weight of the fibrous component P.sub.f.

(47) In the result of Example 3, the average of the values of the ratio between the weight of the component of glass fibers and the weight of the fibrous component Pf is 29.2%, very close to the set value of 30%.

(48) Furthermore, the distribution of the values of the ratio under examination is very homogeneous, as indicated by the low value of data dispersion (standard deviation).

(49) TABLE-US-00003 TABLE 3 Comparison product 140 g/m2 according to the invention with product staple 200 g/m2 according to the prior art - Example 3 New product Prior art Example 3 Reinforced 140 g/m2 staple 200 g/m2 Weight per MD g/m2 140 215 surface unit CD g/m2 139 216 Maximum load MD (N/5 cm) 778 541 CD (N/5 cm) 492 386 Specific load MD daN/5 cm/g/m2 0.56 0.25 CD 0.35 0.18 TOT 0.91 0.43 Elongation at MD % 17 26 break CD % 24 37 Isotropy 1.58 1.40

(50) TABLE-US-00004 TABLE 4 Determination of the degree of homogeneity of the fibrous mixture. SPECIMEN (Pv NO. Pi (g) Pv (g) Pr (g) Pf (g) Pr)/Pf Sample 1 1.725 0.745 0.403 1.190 0.287 Sample 2 1.745 0.777 0.403 1.208 0.309 Sample 3 1.760 0.744 0.403 1.221 0.279 Sample 4 1.750 0.727 0.403 1.212 0.267 Sample 5 1.837 0.813 0.403 1.291 0.318 Average 1.763 0.761 1.224 0.292 Std. 0.043 0.034 0.039 0.021 Deviation