Adhesive membrane

Abstract

A self-adhesive permeable membrane sheet (1), for use in a building structure, includes a continuous layer of a permeable pressure sensitive adhesive (8) attached to one surface of a permeable membrane sheet (2,4,6). Methods for using the permeable membrane sheet (1) in construction are also provided.

Claims

1. A self-adhesive construction membrane sheet comprising a continuous layer of an air and water vapour permeable pressure sensitive adhesive attached to one surface of a permeable membrane sheet, wherein the permeable membrane sheet is: a water vapour permeable air barrier laminated construction membrane comprising three layers: a spunbond polypropylene layer, a microporous polypropylene film layer and a spunbond polypropylene layer, wherein the adhesive mixture used to form the continuous layer of an air and water vapour permeable pressure sensitive adhesive comprises, before drying or curing: an acrylic pressure sensitive adhesive as base compound; an air permeable agent; a cross-linking agent; and polypropylene glycol; so as to provide, after drying or curing, the continuous layer of air and water vapour permeable pressure sensitive adhesive having tortuous air permeable paths therethrough.

2. The self-adhesive construction membrane sheet according to claim 1 wherein the continuous layer of an air and water vapour permeable pressure sensitive adhesive is from 30 to 100 microns thickness.

3. The self-adhesive construction membrane sheet according to claim 1 wherein the water vapour permeability of the continuous layer of an air and water vapour permeable adhesive is 50 perms or more.

4. The self-adhesive construction membrane sheet according to claim 1 wherein the self-adhesive construction membrane sheet maintains more than 70 percent of the water vapour permeability of the permeable membrane sheet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further preferred features and advantages of the present invention will appear from the following detailed description of embodiments illustrated with reference to the accompanying drawing in which:

(2) FIG. 1 shows in schematic cross section a self-adhesive permeable membrane sheet of the invention; and

(3) FIG. 2 shows the application of a shaped portion of the self-adhesive membrane sheet of FIG. 1 as a transition membrane at the corner of a window frame.

DESCRIPTION OF SOME PREFERRED EMBODIMENTS AND EXPERIMENTAL RESULTS

(4) FIG. 1 shows schematically in cross section a self-adhesive permeable membrane sheet 1 of the invention. The sheet 1 consists of three layers 2, 4, 6 of spunbond polypropylene 2, meltblown polyester 4 and spunbond polypropylene 6. A layer of a permeable pressure sensitive adhesive 8 has been applied over all of one surface of the sheet 1. A silicone release paper 10 protects the adhesive layer 8 before use.

(5) FIG. 2 shows schematically a portion of the self-adhesive permeable membrane sheet of FIG. 1 that has been formed into a one piece 3-D corner piece 12 and applied to the corner 14 of a window frame 16 to bridge between the frame 16 and a wall panel 18 which itself is covered with a sheet 1 of the invention. The corner piece 12 ensures continuity of the permeable barrier from the wall panel onto the window frame 16. The rest of the window frame structure 20,22 can be similarly covered by strips of membrane. As an alternative the corner piece 12 and other transition membrane pieces may be fitted first and the sheet 1 applied to the wall panel 18 second to overlap the transition membrane pieces.

(6) Test Results

(7) Preliminary tests for water vapour permeability were carried out using two commercially available membrane products RoofShield and WrapShield. Samples were tested according to Japanese Industrial Standard (JIS) L1099(A-1 method) Vapour Permeability (Dry Cup). The test involves measuring the weight gain in a cup containing anhydrous calcium chloride placed in a chamber in this case at ambient atmosphere of 402 C., 905% relative humidity. An air velocity of 0.8 m/s is applied across the surface of the test piece. The weight gain in the cup over time measures the diffusion of vapour through a test sample of membrane, which seals the top of the cup.

(8) Samples were tested both with and without a layer of permeable adhesive.

Example 1

(9) The adhesive was prepared as a mixture of the following components, 1 to 4, (Available from VIGteQnos Co Ltd of Japan) in the ratio 100:40:2:3 by weight.

(10) 1. AR-2412 Two component cross linked acrylic pressure sensitive adhesive.

(11) Acrylic ester copolymer (39%) Hydrogenerated rhodine ester resin (10%) Acetic ether (ethyl acetate) (50%) Vinyl acetate (1%)
2. AR-739M. Water-absorbent resin (1%) Polypropylene glycol (1%) Water (98%)
3. HD-739D Modified polyisocyanate (20-25%) Silicon dioxide (5-10%) Toluene (50-55%) Acetic ether (ethyl acetate)(15-20%)
4. Tackifier (A xylene resin which improves the initial and extended tackiness of the adhesive film).

(12) This mixture was applied to a release paper, dried and then adhered to the one side of the membranes.

(13) The thickness of the permeable layer was 90 microns.

(14) The results are shown in Table 1 below which shows that with the adhesive layer applied both membrane products retained more than 70% of their permeability.

(15) TABLE-US-00001 TABLE 1 DRY CUP TESTS RoofShield WrapShield No With No With Adhesive Adhesive Adhesive Adhesive Permeability 9249.6 6648 5392 4024 (g/m.sup.2/24 h)

(16) Similar testing but using a wet cup method based on ASTM E96 was carried out to compare the sheets with and without the permeable adhesive, when used to cover a 12 mm thick glass fibre reinforced gypsum board substrate. (A typical panel used in wall constructions). Results are shown in Table 2. Wet cup testing involves measuring the loss of water from a cup through a covering of a sample under controlled conditions.

(17) TABLE-US-00002 TABLE 2 WET CUP TESTS RoofShield WrapShield No With No With Adhesive Adhesive Adhesive Adhesive Permeability 212 145 194 158 (g/m.sup.2/24 h)

(18) Average results from a low number of tests are given in Table 2. Individual results showed significant variation due to the known tendency of the gypsum substrate to exhibit variable properties. Nevertheless the results show that with a suitable continuous layer of a permeable adhesive a gypsum boarding can be covered and protected with a self adhesive membrane sheet and still retain effective water vapour permeability. (The gypsum boarding itself showed a permeability of 197 g/m.sup.2/24 h in the wet cup test).

(19) Adhesive strength tests, at 10 C. and 60 C., were also carried out on samples of the membrane sheets adhered to 12 mm gypsum board. The test employed was the Japanese standard JIS Z0237 (90 degree peel adhesion test). There was no adverse effect on adhesion when adhered to gypsum board at these conditions. At these conditions the vapour permeability of un-adhered samples was not adversely affected over a test period of up to 4 weeks.

(20) Air permeability of RoofShield adhesive coated membrane samples was measured using a method according to Japanese Industrial Standard JIS P8117 (B Method Gurley Test). Tests on the WrapShield adhesive coated samples is not meaningful as WrapShield is an air barrier material. The test measures the time for 300 ml of air to pass through a sample under specific pressure conditions i.e. a low time indicates high air permeability. For example air barrier WrapShield based samples have a test time of 100-200 seconds depending on the sample tested. A RoofShield based sample gave a test time of 2.33 seconds demonstrating high air permeability. Stability testing at 10 C. and 60 C. over 4 weeks indicated a very slight reduction in air permeability after storage at 10 C. and a slight increase after storage at 60 C. However the variations observed lie within the known (i.e. expected) variations in the properties of the membrane materials, therefore no conclusion can be drawn from these apparent changes.

(21) The peel adhesion of permeable membrane layers using the adhesive of example 1 applied to Wrapshield and RoofShield type membranes was tested using a test normally applied to elastomeric joint sealants for roof underlayments. The peel adhesion performance of self-adhered products AC188 (Acceptance Criteria for Roof Underlayments) which references ASTM C794-06 (Standard Test Method for Adhesion in Peel of Elastomeric Joint Sealants). This is a 180 degree peel test conducted at a rate of 2 inches/minute. Samples do not require to be rolled.

(22) Results of the peel tests for samples of membranes of the invention adhered to plywood, oriented strand board (OSB) and concrete are given in Table 3 below.

(23) TABLE-US-00003 TABLE 3 peel tests Average Peel Load (plf) SUBSTRATE Plywood OSB Concrete AVERAGE 43.03 22.58 16.58 CRITERIA 12.0 plf 12.0 plf 12.0 plf

(24) Further peel tests were carried out in accordance with AAMA 711-05 (Voluntary Specification for Self Adhering Flashing Used for Installation of Exterior Wall Fenestration Products) which requires an adhesion level of 0.26 N/mm or above to ASTM D3330 (Standard Test Method for Peel Adhesion of Pressure Sensitive Tape), Method F. This is a 90 degree peel test carried out at 12 inches per minute and samples are rolled at a speed of 10 mm/s.

(25) Results are shown in Table 4 below for samples of membranes of the invention adhered to plywood, oriented strand board (OSB), aluminium, vinyl, DensGlas (gypsum and fibreglass sheathing) and concrete.

(26) TABLE-US-00004 TABLE 4 Peel tests Average Peel Load (N/mm) SUBSTRATE Alu- Plywood OSB minium Vinyl DensGlas Concrete AVERAGE 0.51 0.27 0.30 0.58 0.55 0.29

(27) The criteria for all these substrates is a peel strength of 0.26 (N/mm).

(28) No primers were used in the peel adhesion testing. When trying to peel the membranes of substrates the failure is typically cohesive (the bond with the spun-bond base layer is stronger than the bond between the spun-bond and the melt-blown or microporous film layer).

Example 2

(29) An alternative adhesive composition comprises the same mixture of components as the mixture described above in Example 1 except that component 4, the tackifier (xylene resin) is replaced with polyoxypropylene glycol. The alternative example composition therefore comprises the following components, 1 to 4, (Available from VIGteQnos Co Ltd of Japan) in the ratio 100:15:2.5:2 by weight:

(30) 1. AR-2412 Two component cross linked acrylic pressure sensitive adhesive.

(31) Acrylic ester copolymer (39%) Hydrogenerated rhodine ester resin (10%) Acetic ether (ethyl acetate) (50%) Vinyl acetate (1%)
2. AR-739M Water-absorbent resin (1%) Polypropylene glycol (1%) Water (98%)
3. HD-739D Modified polyisocyanate (20-25%) Silicon dioxide (5-10%) Toluene (50-55%) Acetic ether (ethyl acetate) (15-20%)
4. PP-4000 Polyoxypropylene glycol (100%)

(32) This mixture provides comparable or better results to that of Example 1, even when a thinner coating of 70 microns of the adhesive is applied to the permeable membrane. Water vapour permeability testing (Dry Cup) for a Wrapshield product coated with a 70 micron layer of this adhesive (using the JIS L 1099(A-1 method)) gave a result of 4080 g/m.sup.2/24 hr. This is comparable with the results of example 1 but this high level of vapour permeability is achieved using a thinner (70 micron) layer of adhesive. By comparison the base (Wrapshield) product had a mean permeability in this same test of 4637 g/m.sup.2/24 hr.

(33) Peel adhesion testing of this material (under the same regime as in Table 4 above) was carried out on two substrates, stainless steel and DensGlas (gypsum and fibreglass sheathing). For stainless steel as substrate the mean peel strength was found to be 0.46 N/mm and for DensGlas 0.47 N/mm.

(34) The results for Examples 1 and 2 illustrate the versatility and strength of the adhesives employed, showing that membranes of the invention are suitable for peel and stick use in demanding construction applications.