GB2192892A

GB2192892A - Primer for EPDM roofing membranes

Info

Publication number: GB2192892A
Application number: GB08715000A
Authority: GB
Inventors: Dennis Patrick Miller; Laurence Glenn Dammann
Original assignee: Ashland Oil Inc
Current assignee: Ashland LLC
Priority date: 1986-07-21
Filing date: 1987-06-26
Publication date: 1988-01-27
Anticipated expiration: 2007-06-26
Also published as: DE3723977A1; SE8702921D0; SE8702921L; GB2192892B; DE3723977C2; GB8715000D0

Description

GB2192892A 1

SPECIFICATION

Primer for use on E1PDM roofing materials Roofing materials useful for covering large roof areas are customarily prepared in wide sheets for 5 efficient installation. These wide sheets must be overlapped and spliced together when the roofing sheets are installed to provide uniform surfaces. Overlap splicing is often done under extreme weather conditions and the adhered sections must continue to withstand severe weather at extremes of cold and hot temperatures for many years. Roofing materials are available in black and in various colors including white. 10 Customarily roofing materials, made from plastic, rubber or ethylene propylene diene monomer (EPIDM), have been spliced together on site with neoprene (polychloroprene) based contact adhesives. A well known treatise, the Handbook of Adhesives edited by Irving Skiest, published by Van Nostrand Reinhold Company, 1977 edition, at page 880, recommends the use of neoprene based adhesives on EPDM substrates. 15 EPIDM membranes are a very popular form of single ply roofing. Although black EPDM mem brane is the most widely used, white EPDM membrane is gaining in popularity. Often they are treated with talc, mica, or cellulosic powders to improve processing and handling of the finished membrane. Splice adhesives adhere poorly to these treated surfaces.

It is desirable to use a primer on the EPIDM membrane substrate before applying the neoprene 20 based adhesives. The strength and durability of the final bond between adhesive and substrate depend greatly on the strength of the bond created by the primer. Conventional commercial primers typically provide poor bond strengths of about three pounds/inch when used with neoprene based adhesives. These conventional commercial primers frequently contain environ mentally undesirable ingredients such as lead salts and free isocyanates. When black conven- 25 tional primers are used on white EPIDM roofing membranes special techniques are necessary to prevent the black color of the primer from showing on the final adhered surface.

It is accordingly an object of this invention to provide a durable strong primer for EPIDM roofing to use in conjunction with neoprene based adhesives. A further object of this invention is to provide a primer for EPIDM roofing which is free of environmentally objectionable components such as lead salts and free isocyanates. Another object of this invention is to provide a primer for use on white or other colored EPIDM roofing materials. An additional object of t his invention is to provide a primer for use on surface treated EPDM roofing.

In accordance with the present invention a primer is provided for EPIDM roofing for use in conjunction with neoprene based adhesives which contains neither lead salts nor isocyanates. 35 This durable strong primer is colorless and can therefore be used on any color of EPDM roofing including white. In one embodiment this invention is a primer composition for use on EPIDM roofing membranes which comprises an admixture of 100 parts thermoplastic block copolymer rubber, 10 to 1000 parts halogenated butyl rubber, 10 to 1000 parts reinforcing resin, and sufficient solvent to achieve application viscosity. 40 In another embodiment this invention is a process for adhering EPIDM roofing membranes comprising the steps of (a) cleaning edges of EPIDM roofing membrane with solvent, (b) coating said cleaned edges of EPDM roofing membrane with a primer comprising an admixture of 100 parts thermoplastic block copolymer rubber, 10 to 1000 parts halogenated butyl rubber, 45 to 1000 parts reinforcing resin, and sufficient solvent to achieve application viscosity, (c) allowing said primer to dry, (d) applying polychloroprene based contact cement, (e) allowing said polychloroprene based contact cement to dry, and (f) joining said primed, polychloroprene contact cement coated edges. 50 Both radial block copolymer rubber and linear block copolymer rubber components are useful in the process of this invention. The thermoplastic styrene-ethylene- butylene-styrene (SEBS) block copolymer is preferred. The product sold under the trademark Kraton G 1652 by She[[ Oil Company, Houston, Texas, is particularly useful. This is a thermoplastic rubber crumb product having a styrene rubber ratio of 33:67 and a tensile strength of 3000 psi measured by ASTM 55 method 0412 using a tensile tester jaw separation speed of 10 in./min. Kraton SEBS block copolymers are described in U.S. Patent 4,041,103 assigned to Shell Oil Company.

A number of other thermoplastic rubbers were evaluated for performance in the primer of this invention. None of Solprene 161T, Solprene 190T, Kraton G-1657, Kraton DX- 1300 or Arakawa D-411 were as effective as Kraton G-1652 thermoplastic rubber, all providing only 50% strength 60 performance compared to Kraton G-1652.

The halogenated butyl rubber ingredient is preferably the brominated butyl rubber polymer or brominated isobutylene-isoprene polymer (BIIR) of 46 (ML1 8, 2750F) Mooney viscosity and 1.9% bromine content. The products sold under the trademark Polysar 2030 and Polysar X2 by Polysar Ltd., Sarnia, Ontario, Canada are particularly useful. When 100 parts thermoplastic block 65 2 GB2192892A 2 copolymer rubber are used in the primer of this invention from 10 to 1000 parts halogenated butyl rubber are used. In a preferred embodiment from 50 to 200 parts brominated butyl rubber are used with 100 parts thermoplastic block copolymer. The primer formulations of this inven tion are very specific to raw mat9rial sources for their performance, that is Exxon 2255 bromi nated butyl rubber (which is reported to be equivalent to Polysar X2 brominated butyl rubber) 5 does not give a satisfactory primer when combined with the other primer components.

The hydrocarbon reinforcing resin component useful in the primer of this invention provides needed wetting properties so that the primer will contact the EPDM roofing effectively. This hydrocarbon resin component of the adhesive must be physically compatible with the resin components of the roofing membrane. The hydrocarbon resins useful in the process of this 10 invention act as strength modifiers of the block copolymer component of the primer since the hydrocarbon resins reinforce the styrene blocks of the thermoplastic styrene-ethylene- butylene-styrene block copolymer component. Among the hydrocarbon reinforcing resins useful in the process of this invention are hydrogenated alicyclic hydrocarbons, linear homopolymers of alpha methyl styrene and copolymers of styrene or alpha methyl styrene with monomers such as 15 vinyl toluene, acrylic monomers and butadiene. Suitable hydrocarbon reinforcing resins include Amoco resin 18 polyalpha methyl styrene (Amoco, New York, New York), Picco resin 6070 polymerized C7 to C9 aromatic monomer (Hercules, Wilmington, Delaware) and Endex 160 resin (Hercules, Wilmington, Delaware). From 10 to 1000 parts hydrocarbon reinforcing resin are used with 100 parts thermoplastic block copolymer. 20 The preferred hydrocarbon reinforcing resin for use in the primer of this invention is the resin sold by Amoco Chemicals Corporation, Chicago, Illinois under the trademark Amoco 18-290 polyalpha methyl styrene having an ASTM E28 softening point of 141'C (286F), a molecular weight of 960 and a glass transition temperature of 40'C. From 50 to 200 parts polyalpha methyl styrene hydrocarbon reinforcing resin are used with 100 parts thermoplastic block copolymer in the preferred embodiment of this invention. Table 3 at page 313 of Skiest, Handbook of Adhesives lists Amoco resin 18-290 as an endblock compatible resin useful with A-B-A block copolymer thermoplastic rubbers.

The preferred solvent used to prepare the primer of this invention is toluene. Other solvents such as xylene and other aromatic hydrocarbons, chlorinated hydrocarbons such as monochloro- 30 benzene, aliphatic hydrocarbons, esters, ketones and mixtures thereof are also potentially useful. When 100 parts by weight thermoplastic block copolymer are combined with 10 to 1000 parts halogenated butyl rubber and 10 to 1000 parts hydrocarbon reinforcing resin, toluene in the amount of 3 to 100 parts per 1 part of primer solids is used.

Generally, the solvent is used in an amount such that there is sufficient solvent to achieve 35 appropriate application viscosity in the primer. This appropriate application viscosity corresponds to a percent solids at application of from 5 to 50%. The preferred level of non-volatile solids in the primer is about 10%.

Minor amounts of diphenyl quanidine, a secondary accelerator for rubber curing may also be added to the primer in the amount of 0.01 to 1.0%. Further modification may be made by the 40 addition of carbon black or other pigments to provide theAesired color. Still further modification may be made by the minor addition of silanes, rubber curatives, rubber accelerators or antioxi dants.

In addition to the bonding of EPDM roofing sheeting membrane the primer of this invention is seful on other roof sheeting such as neoprene, Hypalon rubber (DuPont, Wilmington, Delaware), 45 PIB polyisobutylene (Geotac RPM, Medina, Ohio) and polyvinyl chloride sheeting.

The commercially vailable primer usually used on EPDM roofing membrane contains butyl rubber, free isocyanate, lead salts and carbon black and is available as Lord TS-3320-19 primer from Lord Corporation, Erie, Pa. It is available in black only.

The primer of this invention is used in conjunction with polychloroprene (neoprene) based 50 contact cement adhesives. There are many neoprene (polychloroprene) based contact adhesives available commercially. Examples of and formulations for these adhesives are documented in many sources. Such sources include Adhesion and the Formulation of Adhesives, W. C. Wake, Applied Science Publishes. London and Handbook of Adhesives, 1. Skeist ed. , 2nd Ed., Van Nostrand Reinhold Co., New York. Skeist also suggested that a neoprene- based contact adhesive 55 may be used for bonding EPDM rubber in the Handbook of Adhesives.

Currently the most commonly used adhesives for bonding EPDM roofing membrane are based on polychloroprene and phenolic resinate. These materials are dissolved in mixtures of solvents and modified with hydrocarbon resinsl fillers, curatives and stabilizers. Neoprene adhesives of this type are the most suitable for use with the primer of this invention. Representative adhe- 60 sives of this kind are Pliobond 2368 adhesive and Pliobond 2377 adhesive available from Ashland Chemical Co., Columbusl OH; N-100 adhesive available from Carlisle Corp., Carlisle, PA; and Uniroyal 6317 adhesive available from Uniroyal, Inc., Middlebury, CT.

Evaluations of the primer of this invention were made in conjunction with Pliobond 2368 polychloroprene (neoprene) based contact cement adhesive which is used at 24.0% solids by 65 3 GB2192892A weight and has a viscosity of 800 to 1200 centipoise as measured with a number 2 spindle at RPM with a RVT Brookfield viscosimeter.

The following Examples show how the present invention can be practiced but should not be construed as limiting. In this application, all percentages and proportions are by weight and all units are in the metric system, unless otherwise expressly indicated. Also, all citations herein are 5 expressly incorporated herein by reference.

Example 1 (4498-78) This example illustrates the preparation of the primer of this invention. Polysar bromobutyl rubber X-2 at 25% in toluene in the amount of 13.32 grams, Kraton G-1652 block copolymer 10 rubber at 25% in toluene in the amount of 13.32 grams, Amoco 18-290 polyalpha methyl styrene reinforcing resin in the amount of 3.33 grams and 0.20 grams diphenyl quanidine secondary accelerator were blended until solution was completed. Toluene in the amount of 69.83 grams was added and the entire mixture blended until solution was complete.

The primer was applied by brush to a hexane cleaned single ply ethylene propylene diene 15 monomer (EPDM) roofing membrane (sold by Goodyear, Akron, Ohio under the Versigard trademark). After solvent had evaporated pliobond 2368 polychloroprene (neoprene) based contact cement adhesive (Ashland Chemical Co., Columbus, Ohio) for black membrane or Pliobond 2377 polychloroprene (neoprene) based contact cement adhesive (Ashland Chemical Co., Columbus, Ohio) for white membrane was brushed over the primer and allowed to dry. Two such treated 20 pieces of roofing membrane were hand assembled and hand rolled to effect intimate contact.

One inch sample strips were cut from this sheet and compared to a similar bond assembly prepared with a standard commercial primer Lord TS 3320-19 primer (Lord Corporation, Erie, Pa.). Test results were observed on samples aged at room temperature for 1 and 7 days. Peel values were measured using an Instron tester with a crosshead speed of 2 inches/minute with a 25 1 inch wide strip in a t-peel configuration following ASTM D-413 procedure. Test results are reported in Table 1.

Table 1 (4498-78) Peel Values (lbs./in.) 30 Clean Talc White Membrane Membrane Membrane Primer 24 hr 7 day 24 hr 7 day 24 hr 7 day 35 Example 1 4.0 5.0 4.2 5.1 4.1 5.7 Commercial 3.1 3.0 3.3 3.0 3.0 3.0 40 In every test the primer of the invention provided stronger bonds with neoprene based adhesive than the commercial primer.

Example 2 (4498-77) This example illustrates the use of a different bromobutyl rubber in the primer of this inven- 45 tion. The procedure of Example 1 was followed except 13.32 grams Polysar 2030 bromobutyl rubber was used in place of Polysar X2 bromobutyl rubber. The membrane was clean black Versigard membrane. Test results are reported in Table 2.

TABLE 2 50

Peel Values (lbs./in.) Primer 24-hr 72 hrs 7 days Example 2 3.5 4.5 5.0 55 Commercial 3.0 3.9 4.1 omit primer 1.9 1.9 2.0 60 The primer of the invention provided stronger bonds with neoprene based adhesive than the commercial primer.

Example 3 (4498-100) This example illustrates the use of another halogenated butyl rubber in the primer of this 65 4 GB2192892A 4 invention. Exxon 2255 bromobutyl rubber in the amount of 13.32 grams was substituted for the polysar X2 bromobutyl rubber in the formulation of Example 1. The substrate was clean black Versigard membrane. Bonded samples were aged under the conditions of room temperature (RT), 158F air, and immersion in water at 158F. Peel values were determined at the indicated intervals. Results appear in Table 3. 5 Table 3

Peel Value (lbs/in.) 10 Storage Days Aging Primer Condition 1 7 14 28 56 84 112 Example 3 RT 3.8 4.4 4.4 4.9 4.7 4.7 4.6 15 158F Air 3.9 3.1 3.0 2.4 2.0 1.8 1.7 158OF H 2 0 3.1 4.9. 5.5 5.6 4.9 4.3 4.2 Commercial RT 3.1 3.0 2.8 3.0 2.8 2.8 2.9 20 158F Air 5.1 4.7 4.9 5.3 5.2 5.3 5.1 158OF H 2 0 3.6 4.3 4.9 5.3 5.5 5.34.8 25 When Exxon 2255 bromobutyl rubber was substituted for the Polysar bromobutyl rubbers the bond with polychloroprene (neoprene) based adhesive was found to deteriorate over time, this deterioration being most evident at storage conditions of 158'F in air. The Exxon 2255 bromo butyl rubber was not a satisfactory substitute for Polysar bromobutyl rubber in the primer of this invention. 30 Example 4 (4498-86) This example illustrates the use of another thermoplastic block copolymer, Solprene 161T copolymer being substituted for the Kraton G-1652 block copolymer ingredient in Example 1.

The following results were obtained when this primer was used on black Versigard roofing 35 membrane along with Pliobond 2368 polychloroprene (neoprene) based contact cement adhesive.

Table 4

Peel Values (lbs/in.) 40 Primer 24 hours 5 days Example 4 2.1 2 I Commercial 3.0 4.1 45 When Solprene 161T block copolymer was substituted for Kraton G 1652 block copolymer the primer was not as good as the commercial primer control.

Example 5 (4498-104) 50 This example illustrates the use of Endex 160 reinforcing resin substituted for the Amoco 18290 polyalpha methyl styrene reinforcing resin component of Example 1 in the amount.of 3.33 grams. The substrate was clean black Versigard membrane. Results appear in Table 5.

Table 5 55

Peel Values (lbs/in.) Primer 24 hours 72 hours 7 days Example 5 - - 4.6 60 Commercial 3.9 3.9 4.1 At 7 days the primer of Example 5 gave a stronger bond when used with neoprene based adhesives than did the commercial primer. 65 GB2192892A 5 Example 6 (4498) Different amounts of block copolymer, halogenated butyl rubberand modifying resin were tested in this Example to identify optimum levels for each component. The procedure of Example 1 was followed using the proportions indicated in Table 6. The substrate was clean black 5 Versigard roofing membrane. Pliobond 2368 adhesive was used.

Table 6

Kraton 10 Modifying Block Peel Values Bromobutyl Resin Copoly- (lbs/in.) Primer Rubber Amoco mer 24 72 one 15 Sample Polysar 2030 18-290 G-1652 HRS HRS WEEK 4498-90 44.5 44.5 11.0 1.1 1.6 1.8 4498-91 22.3 22.3 55.4 2.3 3.3 4.1 20 4498-92 11.0 44.5 44.5 2.7 3.7 4.4 4498-93 55.4 22.3 22.3 1.2 1.6 1.8 4498-94 44.5 11.0 44.5 3.0 3.8 4.3 25 4498-95 22.3 55.4 22.3 4.2 5.2 5.6 Commercial -- -- -- 3.0 3.9 4.1 Commercial 4.0 5.3 5.7 30 The best bond strengths appear when the primer of this invention comprises from 44.5 to 55.4 parts thermoplastic block copolymer rubber, from 22.3 to 44.5 parts halogenated butyl rubber, from 11.0 to 55.4 parts hydrocarbon resin and sufficient solvent to achieve application viscosity. 35 Example 7 (4998-98) This example illustrates the durability and excellent aging of an EPDM membrane adhesive bond primed with the primer of Example 1 with two parts Codispersion 22-R- 25 carbon black added per 100 parts solids. Bonded samples were aged under the conditions of room tempera- 40 ture (RT), 158'F air, and immersion in water at 158'F. Peel values were determined at the indicated intervals. The substrate was EPDM membrane which had been treated with talc.

Results are reported in Table 7.

Table 7 45

Peel Value (lbs/in.) Days Aging Primer Storage 1 7 14 28 56 84 112 50 Condition Example 1 RT 3.9 4.6 4.5 4.9 4.6 4.9 5.3 158OF Air 4.7 4.9 5.1 4.8 5.0 5.3 5.1 55 158OF Water 3.3 3.4 3.5 3.5 3.4 3.33.3 Commercial RT 3.7 2.9 2.6 2.2 2.3 2.6 2.7 1580F Air 2.8 2.7 2.9 3.5 3.7 3.7 3.5 60 1580F Water 2.2 2.3 2.8 2.8 3.5 3.43.0 The primer of Example 1 aged at 158'F in Air and Room Temperature conditions was superior in performance to the commercial primer. 65 6 GB2192892A 6 Example 8 (4498-78) This example illustrates the superior high temperature peel retention of the primer of this invention compared to the existing commercial primer. Using both talc treated and white EPDM membranes the bonds were assembled as in Example 1. The bonded EPDM was stored at room 5 temperature for 4 days and tested for peel values at various temperatures. The results are reported in Table 8.

Table 8

10 Peel Value Ubs/in) Conditions Primer Membrane RT 120F 158OF 190OF 15 Example 1 Talc 4.6 3.1 2.2 0.9 Commercial Talc 3.7 1.9 0.8 0.7 Example 1 White 5.0 3.3 2.7 1.5 20 Commercial White 3.0 1.7 0.5 0.5 The primer of this invention provided stronger bonds at all test temperatures than the com- mercial primer.

25

Claims

1. A primer composition for use on EPDM roofing materials in conjunction with neoprene based roofing adhesive comprising an admixture of 100 parts thermoplastic block copolymer rubber, from 10 to 1000 parts halogenated butyl rubber, from 10 to 1000 parts aromatic hydrocarbon reinforcing resin, and sufficient solvent to achieve application viscosity. 30

2. The primer composition as recited in claim 1 further comprising from 0. 5 to 5.0 parts diphenyl quanidine based on 100 parts total solids of said admixture.

3. The primer composition as recited in Claim 1 wherein said admixture comprises 100 parts thermoplastic block copolymer rubber, from 50 to 150 parts halogenated butyl rubber, from 50 to 150 parts aromatic hydrocarbon reinforcing resin and sufficient solvent to achieve application 35 viscosity.

4. The primer composition as recited in Claim 3 wherein said admixture comprises 100 parts thermoplastic block copolymer rubber, 100 parts halogenated butyl rubber, 100 parts aromatic hydrocarbon reinforcing resin and sufficient solvent to achieve application viscosity.

5. The primer composition as recited in Claim 2 further comprising carbon black. 40

6. The primer composition as recited in Claim 2 further comprising an anti-oxidant.

7. A process for adhering EPDM roofing membrane materials comprising the steps of:

(a) cleaning edges of E roofing membrane with solvent, (b) coating said cleaned edges of EPDM roofing membrane with a primer comprising an admixture of 100 parts thermoplastic block copolymer rubber, 10 to 1000 parts halogenated 45 butyl rubber, 10 to 1000 parts aromatic hydrocarbon reinforcing resin, and solvent, (c) allowing said primer to dry, (d) applying polychloroprene based contact cement, (e) allowing said polychloroprene based contact cement to dry, and (f) joining said primed, polychloroprene based contact cement coated edges. 50

8. The process as recited in Claim 7 wherein the primer of step (b) further comprises from 0.5 to 5.0 parts diphenyl guanidine based on 100 parts total solids of said admixture.

9. The process as recited in Claim 7 wherein the primer of step (b) comprises 100 parts thermoplastic block copolymer rubber, from 50 to 150 parts halogenated butyl rubber, from 50 to 150 parts aromatic hydrocarbon reinforcing resin and sufficient solvent to achieve application 55 viscosity.

10. The process as recited in Claim 9 wherein the primer of step (b) comprises 100 parts thermoplastic block copolymer rubber, 100 parts halogenated butyl rubber, 100 parts aromatic hydrocarbon reinforcing resin and sufficient solvent to achieve application viscosity.

11. The process as recited in Claim 7 wherein the primer of step (b) further comprises carbon 60 black.

12. The process as recited in Claim 7 wherein the primer of step (b) further comprises an antioxidant.

13. A process for adhering EPDM roofing membrane materials substantially as described according to any one of the Examples herein. 65 7 GB2192892A 7 Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC I R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.