Glass-fibre textile structure with parylene coating

Abstract

The invention relates to a glass-fiber textile structure, characterized in that it has a parylene (poly(para-xylylene)) coating with a thickness of between 5 m and 30 m, preferably between 6 m and 25 m, in particular between 7 and 20 m. The invention also relates to a method for reinforcing a solid material, which comprises introducing such a textile structure having a parylene coating into a fluid base material, preferably a base material comprising water and a hydraulic binder, and curing the base material.

Claims

1. A method for reinforcing a solid material, the method comprising: introducing a textile structure made of glass fibers and bearing a parylene (poly(para-xylylene)) coating having a thickness of between 5 m and 30 m into a fluid base material comprising water and a hydraulic binder and having a basic pH greater than 8; and curing the fluid base material.

2. The method according to claim 1, wherein the glass fibers are A, E or C glass fibers.

3. The method according to claim 1, wherein the textile structure is made of glass fibers held together or coated by a binder, and wherein the glass fibers represent from 30 to 95% of the weight of the textile structure before deposition of the parylene coating.

4. The method according to claim 1, wherein the parylene is parylene C (poly(2-chloro-paraxylylene)).

5. The method according to claim 1, wherein the parylene coating represents from 5 to 200% relative to the weight of the textile structure before deposition of the parylene coating.

6. The method according to claim 1, wherein the parylene coating completely covers the entire surface of the textile structure so as to isolate the textile structure from the atmosphere.

7. The method according to claim 1 wherein the fluid base material has a basic pH greater than 10.

8. The method according to claim 1, wherein the parylene (poly(para-xylylene)) coating has a thickness of between 6 m and 25 m.

9. The method according to claim 1, wherein the parylene (poly(para-xylylene)) coating has a thickness of between 7 m and 20 m.

10. The method according to claim 1, wherein the glass fibers are E glass fibers.

11. The method according to claim 1, wherein the textile structure is made of glass fibers held together or coated by a binder, and wherein the glass fibers represent from 40 to 85% of the weight of the textile structure before deposition of the parylene coating.

12. The method according to claim 11, wherein the parylene is parylene C (poly(2-chloro-paraxylylene)).

13. The method according to claim 1, wherein the parylene coating represents from 8 to 160% relative to the weight of the textile structure before deposition of the parylene coating.

14. The method according to claim 1, wherein the textile structure is selected from the group consisting of multifilament yarns, rovings, non-woven mats bonded by an organic binder, cloths, woven grids, knit grids, and laid scrims.

15. The method according to claim 1, wherein the fluid base material has a basic pH greater than 9.

Description

EXAMPLE 1

(1) A coating of parylene C with uniform thickness of about 10 m is deposited on a non-woven mat of E glass fibers having a grammage of 50 g/m.sup.2, the fibers of which are bonded with 25% of an organic binder having a base of urea-formaldehyde resin.

(2) The non-woven mat next undergoes an aging test in an alkaline environment as defined in ETAG 004 (Technical guide for external facade insulation systems), which takes place as follows:

(3) 20 rectangular specimens are cut with dimensions of 300 mm50 mm from the non-woven mat bearing the parylene coating. For half of the samples, the length (300 mm) is parallel to the machine direction; for the other half of the samples, the length is perpendicular to the machine direction.

(4) All 20 samples are submerged for 28 days, at a temperature of 23 C., in 4 liters of an alkaline solution having the following composition: 1 g/l of NaOH, 4 g/l of KOH, 0.5 g/I Ca(OH).sub.2.

(5) After 28 days submerged, the samples are rinsed for 5 minutes in an acid solution (5 mL of HCl diluted at 35%), then successively placed for 5 minutes in 3 water baths of 4 liters each.

(6) The samples are next dried for 48 hours at a temperature of 23 C. (2 C.) and a relative humidity of 50% (5%).

(7) The mechanical resistance to traction is next determined using a MTS Insider bench operating with a traction speed of 100 mm/minute.

(8) Table 1 shows the breaking strength in traction (BST expressed in N/5 cm) of the samples cut parallel to the machine direction and perpendicular to the machine direction, before and after exposure to the aging test, compared with samples of an identical non-woven mat having undergone the same treatment, but not having been coated beforehand with parylene. The values shown in the table are the averages (standard deviation) calculated from 10 samples.

(9) TABLE-US-00001 TABLE 1 With Without parylene parylene Traction in the direction BST before aging 341 62 243 14 parallel to the machine BST after aging 266 19 57 10 direction of the non- BST conservation 77% 23% woven mat rate Traction in the direction BST before aging 239 86 155 61 perpendicular to the BST after aging 206 21 66 33 machine direction of the BST conservation 86% 43% non-woven mat rate

(10) One can see that the aging of the non-woven mats, after exposure to alkaline conditions, is significantly slowed by the presence of the parylene coating.

EXAMPLE 2

(11) A layer of parylene 10 m thick is deposited on a spun yarn of E glass having a count of 68 tex before deposition and of 100 tex after deposition of the parylene.

(12) Ten samples of this yarn are subjected to the Strain in Cement test described in standard EN14649:2005 (Precast concrete productstest method for strength retention of glass fibers in cement and concrete (SIC-TEST)).

(13) Table 2 below shows the evolution of the tenacity (expressed in cN/tex) and the modulus of elasticity (expressed in GPa) of the yarn coated with parylene during the test, compared with the same yarn not coated with parylene (68 tex).

(14) TABLE-US-00002 TABLE 2 Yarn with Yarn without parylene parylene Count (tex) 100 68 Initial tenacity (cN/tex) 56.2 87.1 Final tenacity (cN/tex) 22.8 3.2 Tenacity conservation rate 40.5% 3.7% Initial modulus of elasticity (GPa) 44.7 6.3 59.2 2.7 Final modulus of elasticity (GPa) 40.1 1.7 12.8 6.8 Modulus of elasticity conservation rate 89.7% 21.6%

(15) Depositing a parylene protective layer allows nearly 90% of the modulus of elasticity to be retained, versus only 21% for the control yarn with no parylene deposit. The same is true for the tenacity, which is significantly less degraded in the presence of parylene compared to the absence thereof.

(16) The layer of parylene C coating the reinforcing yarns made from E glass thus constitutes effective protection of the glass yarns from chemical attacks by the alkaline components of the cementitious material.