Accordingly it is an object of this invention to provide an improved room temperature-curable adhesive system which achieves at least equal peel strength as the prior heat cured adhesives and eliminates the dangers associated with torching.

Another object is to provide an adhesive sealant which is deformable in conformity to changes in membrane joints during the process of curing and which possesses high weatherability and thermal stability as well as resistance to degradation by heat, water, chemicals and exposure to ozone.

These and other objects an advantages will become apparent from the following description and disclosure.

THE INVENTION In accordance with the present invention there is provided an adhesive composition comprising: (a) between about 0.5 and about 15 wt. % of a polymer comprising from about 10 to about 100 wt. % of a thermoplastic block polymer of styrene, ethylene and butadiene or butene, i. e. SEBS and optionally from 0 to about 90 % of an elastomer; (b) between about 24 to about 48 wt. % of a solvent having a boiling point below the flash point of the adhesive composition which consists of an aromatic hydrocarbon, optionally containing a minor amount of aliphatic hydrocarbon; (c) between about 20 and about 50 wt. % of a C8 to C12 hydrocarbon non-blown asphalt having a penetration of between 50 and 120 decimillimeters (dmm) at 25°C. employed in a weight ratio, (b) to (c), of from about 1: 1.3 to about 1: 4; (d) between about 1 and about 10 wt. % of a metal silicate; (e) between about 0.1 and about 5 wt. % of a C6 to C 16 alkoxyalkylamine substituted ester of a C2 to C 12 carboxylic acid; (f) between about 10 and about 30 wt. % of an anhydrous inorganic filler; (g) between about 0.5 and about 10 wt. % cellulose fibers of not more than 0.06 mm diameter; (h) between 0 and about 10 wt. % water and (i) between 0 and about 10 wt. % latex combined to form 100% of a homogeneous adhesive mixture containing from about 60 to about 75 % solids. The present adhesive can be employed as a field adhesive on atactic polypropylene and SBS modified building material sheets for joining adjacent members to provide a strong roofing or siding assembly or as a lap adhesive for sealing laps and side seams of building material sheets. The adhesive can also be used as more viscous trowel adhesive, particularly adapted to vertical substrates such as siding. The present field adhesive has a Brookfield viscosity of from about 60 to 140 cps, preferably from 70 to 120 cps, using spindle 4 at 3 rpm. The lap and trowel adhesives have penetrations of from about 320 to about 385 dmm and from about 110 to about 225 dmm respectively.

All of the above types have a weight of from about 7.5 to about 10 lbs/gal.

Useful and representative formulations for each type of adhesive are illustrated in following Table I.

TABLE I Adhesive Field Adhesive Lap Adhesive Trowel Adhesive Component wt. % wt. % Wt. % Range Preferred Range Preferred Range Preferred a 4-10 7-8 4-15 8.5-9.5 0. 5-7 2-3 b 30-48 35-38 25-45 30-32 24-40 26-30 c 20-45 28-31 20-45 25-30 25-50 30-40 d 2-6 3-5 1-6 2-3.2 4-10 5-8 e 0.1-5 1-3 0.1-5 0.5-5 0.1-1.5 0.5-0.8 f 10-25 18-22 10-25 20-22 15-30 18-25 g 0.5-5 1.5-2.5 0.5-7 3-8 2-10 0.8-2 h 0 0 0 0 1-10 2-5 i 0.1-3 0.3-9 0.5-5 0.8-2 0 0 As indicated above, the SEBS thermoplastic block polymer of component (a) may contain up to 90% elastomer, such as isoprene, neoprene, SBS, polyisobutadiene, polyisoprene, styrene/butadiene (SBR), styrene/isoprene (SIR), styrene/isoprene/styrene (SIS), hydroxylated styrene/butadiene/styrene (SEPS), ethylene/propylene/diene rubber (EPDM), ethylene/propylene rubber (EBM), atactic polypropylene (APP), styrene/butadiene or cyclized natural rubber, e. g. Pliolite, and mixtures thereof. The preferred composition contains from about 50 to 95 % SEBS.

The solvent of component (a) contains from about 50 to about 100% aromatic hydrocarbon, which has a boiling point below the flash point of the adhesive composition which is between about 105° and about 125°F. Suitable solvents include mineral spirits, naphthas, toluene, xylene and higher molecular weight compounds such as C9 to C 12 aromatic hydrocarbons. Solubilizing component (b) may also contain up to about 50% odorless aliphatic C6 to C8 hydrocarbon and mixtures thereof. The preferred solvent is a mixture in which a major portion is aromatic, for example about 60% or more aromatic hydrocarbon.

The present composition also contains a non-blown asphalt having a penetration of between 50 and 120 dmm at 25°C. The asphalt functions as a tackifier and is preferably used in a weight ratio of from about 1: 1. 3 to about 1: 4, most preferably from 1: 1.5 to 1: 3, based on component (b) to (c).

The homogeneity of the adhesive composition is enhanced by the metal silicate as component (d) which, in concert with the surfactant of component (e), acts to augment wetting and coalescing properties.

Suitable metal silicates include substantially anhydrous minigels of calcium, magnesium and/or aluminum silicates. Preferred of this group are thixotropic minigels, e. g. Mg silicate, e. g. MinuGel G-35 and Minugel AR. Attapulgite and montmorillonite clays, as well as mixtures of the above, are also suitably employed as component (d) in the present composition.

The non-ionic and/or cationic surfactant component (e) of the composition is an oxygen-containing aminoester of a Cr to C, carboxylic acid and having from 6 to 16 carbon atoms in an alkyloxyalkylamino group. These esters can be derived from C6 to C 16 rich alcohol mixtures.

Examples of such surfactants include isodecyloxypropylamino acetate, dodecyloxyethylamino butyrate, nonyloxybutylamino acetate, etc. Of these, isodecyloxypropylamino acetate is preferred.

The anhydrous inorganic filler of the composition includes carbon black; metal oxides, e. g. calcium, magnesium, aluminum, titanium and zinc oxides; metal carbonates and/or metal sulfides and the like. Inert anhydrous materials such as talc, clay, mica, diatomaceous earth, natural rubber particles petroleum resin and the like can also be used as extenders for the adhesive in a form and amount which does not cause phase separation.

The fibers employed in the composition for added body, strength and reinforcement, are also employed in a form and amount which avoids phase separation. For the present purposes, cellulose fibers having a diameter of not more than 0.06 mm, preferably between about 0.01 and about 0.03 mm, are employed. Most preferred are those fibers having a length of between about 0.05 and about 1.5 mm. To customize the adhesive for particular applications, water or latex can be added to adjust the viscosity of the composition. Other excipients, such as a hindered phenolic antioxidant, a LJV absorber, etc. are optionally added to the composition to perform particular functions.

In general the adhesive composition of this invention is a homogeneous product preferably containing between about 65 and about 70 wt. % solids. The viscosity of the preferred composition is 70-120 cps and the weight is between about 7.5 and 10 lbs/gal. The composition can be troweled, mopped or sprayed on the substrate membrane surface at ambient temperature to provide a durable, weather resistant adhesive coating having high peel strength and excellent moisture impervious properties.

The above described adhesive composition is prepared by mixing component (a) and solvent (b) in a high speed mixer preferably operated at a speed of between about 200 and 400 rpm, to provide a homogeneous liquid. The silicate gel, surfactant and non-blown asphalt are separately combined and stirred in a mixer operating at a low speed not in excess of 100 rpm, preferably between about 40 and about 75 rpm. Filler and fibers are subsequently introduced into the silicate mixture and, after a uniform mixture is obtained, the solvent/polymer mixture is introduced and mixed at low speed to provide the homogeneous adhesive product of the present invention which is collected and stored in sealed containers to prevent curing due to solvent loss. This process is effected at ambient or room temperature, i. e. between about 45° and about 100° F.

A typical roofing or siding assembly, wherein the present adhesive is employed to bond layers or seal seams between underlayment strips or sheets, can include a top or cap sheet, usually having 2 to 6 inch overlapping margins or selvage edges; an intermediate insulation layer and a bottom base sheet, which assembly is placed over a wood, metal or cement roof deck or construction siding. The top sheet in the roofing assembly is desirably surfaced with weather resistant mineral granules.

When the adhesive is applied on a membrane to unite sheets or to affix granules on a membrane surface, coatings of from about 1.5 to about 2.5 gals/square of membrane or coatings of 0.1 to 50 mils thickness have been found useful. A somewhat lighter, or lower viscosity coating, between about 0.6 and about 0.85 gals/sq. can be used when sealing abutted or overlapping seams of membrane sheets. Generally, the cure time for the present composition is from 40 hours to 20 days depending on atmospheric conditions.

Having generally described the invention, reference is b now had to the following examples which illustrate preferred embodiments but which are not to be construed as limiting to the scope of the invention as set forth in the appended claims.

EXAMPLE 1 Formulation for Field Adhesive PART A Into a stainless steel mixer, 538.65 g. of 92.27% SEBS containing 7.73% of SBS elastomer (G1650 supplied by Shell Chemical Co.) was mixed at a high speed of 300 rpm, with 65 g of aromatic naphtha solvent (HI-SOL supplied by Koch Chemicals). Mixing was carried out at room temperature until a uniform consistency was obtained.

PART B In a separate stainless steel twin screw mixer, 214 g of non-blown asphalt in 122 g. of HiSol is blended at low speed (50 rpm) with 15.5 g. of magnesium silicate (Minugel, supplied by Crozier Nelson Co.) and 2g of isodecylpropylamine acetate surfactant (Surfactant PA 14 supplied by Tomah Products). About 96.7 g of talc filler, 9.65 g of cellulose fibers having an average fiber 0.03 mm diameter and 1 mm length and 3.09 g of SBR latex rubber (Pliolite, supplied by Goodyear Tire & Rubber Co.) were then gradually added over a period of about 40 minutes and mixing was continued at room temperature and low speed until a uniform composition was obtained.

Finally, the polymer/solvent mixture of part A was added to part B and mixing continued at low speed until a homogeneous product containing 65% solids was obtained. The recovered product had a viscosity of 97 cps.

EXAMPLE 2 At ambient temperature (about 80° F.) the adhesive product of Example 1 was coated (2 gals/sq) on the top surface of a roofing sheet. A second sheet was placed over the coated sheet and, after about 5 hours, in the absence of applied heat, the contiguous layer of adhesive between the sheets was cured. The resulting assembly had a peel strength substantially equal to that of a heat bonded adhesive, namely about 13.5 foot lbs/inch.

EXAMPLE 3 Formulation for Trowel Adhesive Example 1 was repeated except that fibers was employed for the Pliolite and the adhesive product had a penetration of 180 dmm.

The adhesive product of the above example was coated (10.75 gals/sq.) on the surface of a roofing membrane and allowed to stand at about 85°F. for 40 hours in the absence of applied heat. The product was examined and found to be completely cured and exhibited high peel strength and a penetration of 170 dmm.

EXAMPLE 4 The properties of Example 3 product were compared with those of PERMASTIC, a commercial cold weld adhesive supplied by Performance Systems. The results are reported in following Table II TABLE II ADHESIVE TENSILE STRENGTH* PEEL STRENGTH** lbs/in lbs ch of lap width lbs/inch of lap width Product of Ex. 1 141 13 PERMASTIC 55 9 * using CGSB-51 test * * using ASTM method EXAMPLE 5 Formulation for Lap Adhesive The procedure described in Example 1 was repeated except that 77 g of 15.4% aromatic solvent containing 9.2% C9 to C, 4 aliphatic hydrocarbon solvent was substituted in Part A for the 48.65 g of aromatic naphtha. In Part B., 135.5 g of non-blown asphalt, 13.5 g Minugel, 2 g of PA-14,102.5 g of filler and 23.5 g. of fiber having an average 0.03mm diameter and 0.05mm length was substituted in Part B. The resulting product of 65% solids had a penetration of 355 dmm.

METHODS OF COATING MEMBRANES EXAMPLE 6 Single Surface Coating A base sheet was mechanically fastened to an isocyanate insulation sheet which covers a steel roof deck. About 1.75 gals/sq of the present field adhesive was applied over the base sheet. Finally a fire retardant top sheet was laid over the coated base sheet. The resultant adhesive was cured within 2 days and exhibited strong adhesion and high peel strength.

EXAMPLE 7 Membranes with Multiply Surface Coatings A 0.5 inch wood fiber insulation board was mechanically fastened to a wood roof deck and about 1.75 gals/sq of field adhesive was applied over the board. A fiber glass base sheet was placed over the coated insulation board and another application of 1.75 gals/sq. was coated on the exposed surface of the fiber glass base sheet. Finally a fire retardant actactic polypropylene (APP) modified cap sheet was placed over the coated fiber glass sheet. The cure time and product properties were substantially the same as found above in Example 6.

As an alternative to the above example the two coatings of adhesive could be applied to the top and bottom surfaces of the fiber glass sheet in place of the separate applications to the insulation and fiber glass sheets. Many other alternatives within the scope of this invention will become apparent to those skilled in the art.