US3247636A - Elastic flashing composition - Google Patents

Description

A age, they tend to develop leaks around nail holes.

3,247,636 ELASTHC FLASHENG CQMPGSTTIUN William Mick, Midland, ()liver B. Ansley and Don L.

Stevens, Sanford, and Arnold 0. Mack, Midland, Wicln,

assignors to The Dow Chemical Company, Midland,

Mich, a corporation of Delaware No Drawing. Filed Dec. 16, 1960, Ser. No. 76,091

1 Claim. (Cl. 52+3ti9) This invention relates to improvements in compositions that are especially well suited to prepare resilient sheet material of the type particularly adapted to be employed as flashing in and for various construction assemblies.

It is standard construction practice to use flashing in exposed angles between roof and gutter, or in valleys between intersecting roof surfaces, over fascia boards, at joints between masonry or metal and wood (as where chimneys or vent pipes intersect a roof and where masonry parapet walls abut a wooden roof) and between wooden and masonry members of sill structures at floors or windows, as well as in many other places where similar problems exist. The nature of the flashing empolyed generally varies according to the type and intended permanence of the structure. The more durable flashings heretofore employed have been sheet copper or sheet lead. Less permanent flashings can be made of galvanized iron or of a tar-impregnated roofing paper. Recently, in quality installations, a particular type of resilient plastic sheet material has been used for the purpose.

Each of the conventional flashings has some serious recognized shortcomings. Thus, the sheet metal flashings are difficult to seal tightly, especially at joints involving wooden structural supports. Nails driven through such flashing to hold it in place establish potential leaks.

A These, of course, tend to become progressively worse as electrolysis occurs at the point of contact between the nail and the flashing.

There are atmospheric conditions, especially in factory districts or in coal-burning communities, which exert an accelerated corrosive effect on metal flashings. Joint-s in metal flashing must be made by Welding (as in the case of lead) or soldering. Such operations are slow and expensive, and in addition, require considerable skill for proper results.

Flashings made of roofing paper are weak. As they They also, particularly on aging, become brittle in cold Weather. They are, in addition, combustible.

Besides, none of the prior metal or tar-impregnated paper flashings have been resilient enough to be safely walked on without permanent or damaging deformation.

In attempting to overcome some of the defects of prior flashing materials, some use has been made of rubber sheeting. While this has been relatively easier to apply, it also has pronounced and disadvantageous drawbacks. Thus, it is not long-lived, since it oxidizes and becomes brittle and weak in the course of a very few years.

As has been indicated, a particular type of resilient, synthetic, thermoplastic sheet has, despite its comparatively recent origin, been used as flashing with considerable satisfaction and success. Although this type of flashing gives very good service when installed in fairly moist climates, some difficulties are encountered when it is installed and subjected to weathering in hot and dry climates.

Among the properties and characteristics that advantageously could be ameliorated of the referred-to type of synthetic flashing are: its tendency to stiflen with age; the limited storage or warehouse life of the material under certain conditions; and the criticality of the extrusion temperature at which it can be fabricated.

Accordingly, it would be desirable, and it is the prin- United States Patent 3,247,636 Patented Apr. 26, 1966 cipal object of the present invention, to provide a new, long-lived, resilient, self-extinguishing, non-curable, thermoplastic, flashing material.

It is also an object of the invention to provide superior flashing material adapted to be fabricated over a wide range of extrusion temperatures and stored for extended periods of time without curing.

It is a further object of the invention to provide a longlived, resilient, flashing material which retains substantially its original flexibility and elongation under a wide variation of climatic conditions over extended periods of time.

Yet another object of the present invention is to provide a new flashing material which does not deteriorate or spoli-ate the properties of wooden members to which it is bonded, sealed or otherwise attached.

Still another object of the present invention is to provide a non-curable, thermoplastic, flashing material of corrosion resistant character for use in construction.

A still further object of the invention is to provide a thermoplastic flashing material which is easily sealed to other sheets of like material and which forms a tight seal around nails and other fastening devices that are driven through it.

An additional object of this invention is to provide a thermoplastic flashing material which is not damaged or permanently deformed when subjected to temporary localized stress.

These and cognate objects and related benefits and ad vantages are realized by means of the non-curable, resilient, thermoplastic compositions of the present invention which are adapted to be advantageously fabricated into flashing materials for use in various construction assemblies where such components are in order.

Flashing material in accordance with the present invention is a sheet having a thickness generally on the order of 0.06 inch which is formed from a polymeric composition (also in accordance with the invention) that comprises an essentially homogeneous admixture of a copolymer of from about to about 88 percent of interpolymerized vinylidene chloride and from about 20 to about 12 percent of interpolymerized acrylonitrile, a plasticizing agent or a combination of plasticizers for the copolymer which are present in proportions of from about 20 to about 80 parts by weight for each parts by weight of the copolymer, and from about 30 to about 100 parts by weight of a suitable soft filler or reinforcing substance per 100 parts by Weight of the copolymer.

The flashing material of the present invention is in a non-cured or unvulcanized state when incorporated in the structure of which it forms a part and remains substantially unvulcanized, with the advantages to be described, on aging.

The compositions and resulting flashings of the invention are notably improved against prolonged atmospheric deterioration which may tend to undesirably degrade other resilient, cured, thermoplastic, flashing materials.

Surprising as it may seem, it is only when the vinylidene chloride/acrylo-nitrile copolymer is constituted in the specified proportions of interpolymerized comonomers that the highly useful and advantageous product of the present invention is obtained. Greater proportions of vinylidene chloride result in copolymers which cannot be compounded to a useful, suitable, yet unvulcanized state capable of yielding resilient sheets on fabrication thereof. The same is true of such copolymers prepared with more than the stated proportions of interpolymerized acrylonitrile.

The improved compositions useful for flashing stock according to the present invention require the presence of plasticizers in the stated range of proportions if the prodnot is to have the required workability in the raw or noncured, thermoplastic state. Required toughness and re silience needed during the handling and installation of the flashing material is also ensured by the presence of plasticizers in the specified proportions.

The plasticizers useful in practice of the present invention are selected from certain of those known to be effective in vinyl resin plasticization. However, the plasticizers that are suitable for utilization are not recognizable from ordinary practices and established criteria in the vinyl polymer art. For example, dioctyl phthalate, dioctyl sebacate, dioctyl adipate, and many other common plasticizers for standard vinyl polymers do not flux readily with the copolymer that is utilized in practice of the present invention. Thus, they are not particularly suitable for use in the present compositions.

Nonetheless, the sole plasticizers (or primary plasticizers in plastifying combinations thereof) that are satisfactory for practice of the present invention may be selected from a wide variety of plasticizing materials. Besides flexibility, another essential requirement for the plasticizer is that it be substantially non-volatile. This is imperative.

The effectiveness of various compounds as plasticizers for the copolymer compositions of the present invention may be readily determined by conducting a volatility or weight loss test. In this test, the vinylidene chloride/ acrylonitrile copolymer to be used in practice of the invention is blended into a homogeneous admixture with the trial plasticizer in a ratio of about 40 parts of the plasticizing compound to about 100 parts of copolymer resin. About 40 parts of finely divided carbon black and about 1.0 part of stearic acid is included in the formulation. The blended ingredients are compression molded and trimmed, if necessary, in the form of 0.04 x 1 x 1 inch test specimens.

Volatility of the plasticizer is determined from the test specimens by measuring weight loss thereof after a one week exposure in a circulating oven at about 150 F. For purposes of this invention, the plasticizer employed should, in the test described, have a volatility or weight loss that does not exceed about 1.5 percent, based on original plastified composition weight.

Representative of suitable primary plasticizers for use in the present flashing compositions are dicarbitol phthalate; ethoxy diglycol phthalate; n-butyl benzyl phthalate; and dibutyl phthalate. Still other plasticizers adapted for use in the present invention are, on the basis of requirements therefore, apparent. Selection may be made in specific instances following routine and straightforward preliminary testing on the above-indicated basis.

'Certain other compatible plasticizers may be incorporated in the formulation as secondary plasticizers. Typical of these are: the polyvinyl ether polyester obtained as Harflex 200; a polyester from C mono and dibasic acids (i.e., Plastalein 9720); butyl phthalyl butyl glycolate obtained as Sanitizer Bl6; a high molecular weight alkyl polyester obtained as Paraplex G-53; a polyvinyl ether derived from neopentyl glycol obtained as Eastman NP; and dipropylene glycol dibenzoate obtained as Benzoflex 9-88. Each of these plasticizers has certain limitations which preclude its use as the primary plasticizer in the present formulation. However, one or more of these plasticizers can be employed as a secondary plasticizer (i.e., as a replacement in part for the previously mention-ed primary plasticizer) to produce eflicacious compositions for certain specific uses.

It is apparent that the nature and identity of the plasticizing ingredient is critical. Itmust be compatible with the copolymer in the stated proportions. The least volatile plasticizers will normally give compositions having the longest life. However, for the purposes of initial flexibility, a small amount of any one of the group of relatively volatile plasticizers, delineated in the foregoing as useful secondary plasticizers, may be used in the com positions of the invention.

The presence of an amount of soft filler or reinforcing compound in the stated range serves the purpose of strengthening the sheets made from the composition of the present invention. The reinforcing compound in the compositions for the flashing is usually carbon black of the kind Widely used in the rubber art and known therein. as a soft reinforcing carbon. Such a material has a specific gravity of about 1.80, a particle size of about 99.9 percent through a 200 mesh screen (US. Standard sieve series); and a moisture and ash content at l00l05 C. of about 0.5 weight percent, maximum.

Known rubber pigments and fillers may be incorporated in the composition, if desired, in amounts insufficient to give stiff or rigid sheets. Such pigments and fillers may be employed to impart various colors to the flashing material in order to have it harmonize or contrast with the color of the placement surface.

The composition can be prepared in many ways. One convenient manner is to mix together the powdered copolymer, carbon black and any other dry powdered ingredients (if any be used). Then, after suitably warming the mixed ingredients at a temperature well below the fusion or softening temperature of the copolymer, the plasticizer or combination of plasticizers is added. After, this, the mixing of the formulation is continued until a uniform, homogeneous mass is obtained. It may be advantages, at this stage, to add small amounts of stearic acid or other known roll-release agents. The resulting mixture is thoroughly blended in a ribbon blender or similar device and thereafter extruded into a continuous sheet. For use as flashing, the sheets are preferably made in thicknesses of from about 0.03 to about 0.12 inch. A convenient and generally useful thickness, as has been indicated, is about 0.06 inch. Of course, thinner or thicker sheet material may be made and employed in various applications, as may be desired or required in particular instances. Even in sheets thicker than about 0.12 inch, however, the flashing material of the present invention retains its many inherent beneficial attributes and properties.

The uncured sheets of the present invention make possible the formation of a permanent bond between overlapping areas of adjoining sheets or strips of the flashing, as well as the formation of a tight bond that conforms closely to metal or masonry surfaces. This is the case even when the surface being sealed is of irregular contour. Such bonds between adjoining sheets of the composition are made by moistening the touching surfaces of the lapped sheets with a solvent. Advantageously a ketone (such as acetone, methyl ethyl ketone, or methyl isobutyl ketone) is employed for the purpose. The solvent-wet surfaces are then pressed together to secure the desired moisture-proof joiner.

When there is no combustion hazard (as, for example, in the installation of flashing or waterproof sheathing or subgrade masonry foundations), joints between sheets of the flashing may be made by playing a flame (as from a blowtorch) or heat from infrared lamps on the overlapped sheets. Other available sources of heat may be employed to effect evaporation of the solvent from the moistened overlapping surfaces of the flashing and thus ensure the seal.

Bonds between the new flashing and metal or masonry surfaces are readily made by applying to one, or both, of the intended contacting surfaces an adhesive comprising, as part of its solvent component, a ketone or a cyclic ether (such as dioxane or tetrayhydrofuran) which is capable of superficially softening the flashing. An especially useful adhesive comprises a ketone solution of an adhesive vinyl polymer or a ketone solution of an adhesive vinyl ester/synthetic rubber blend. Commonly, a dilute adhesive of this type is applied as a prime coat on the metal or masonry surface. This is allowed to dry to a tacky state. After this, there is applied over the dried adhesive layer a more concentrated adhesive formulation of the same type. The flashing is pressed into place before the adhesive has finally dried. useful commercial adhesive for the purpose is aproduct of Amercoat Corporation, obtained as Amercoat 20-Y Adhesive. This material is a composition of a vinyl ester polymer dissolved in a ketone. Another particularly useful adhesive for the instant purpose is a product of the Minnesota Mining and Manufacturing Company, obtained as 3M Adhesive EC1369. This adhesive is believed to be a polyvinyl ester/synthetic rubber blend dissolved in a ketone.

It may be desirable in some parts of a structure to secure the flashing to wooden members by means of an adhesive. In such case, the general type of adhesive described above is satisfactory. However, in many types of installation the flashing will be fastened to wooden members by mailing. In the latter case, especially when large headed roofing nails are used, no washer or gasket is required about the nail. The flashing is not under such tension as to tear away from the nail, and there is no danger of embrittlement.

In order that those skilled in the art may better understand how compositions in accordance with the present invention may be prepared, the following examples are given by way of illustration and not by way of limitation. All parts and percentages in the examples are by weight.

Example I Into a ribbon blender there were charged: about 100 parts of a copolymer of about 82 percent interpolymerized vinylidene chloride and about 18 percent interpolymerized acrylonitrile; about 40 parts of powdered, medium, thermal (Thermax) reinforcing carbon having an average particle size of about 450 millimicrons in which at least 99.9 percent passed a 200 mesh screen (U.S. Standard sieve size); about 4.0 parts of litharge; about 40 parts of dibutyl phthalate plasticizer; about 1.0 part of stearic acid and about 2.5 parts of acetone. The charged ingredients were blended thoroughly in the blender.

The blended ingredients were then extruded at a temperature of about 250 F. A mixing type extruder was employed for the purpose to fabricate the composition into a continuous sheet of about 0.06 inch thickness.

For comparison, a similar sheet was made from the compositions described in US. 2,614,092. This was a cured composition.

A sheet of each formulation was then subjected to accelerated weathering conditions. Specimen samples of the sheets were tested for flexibility, elongation, and weight loss at specific intervals. The results of these tests demonstrated conclusively the superior retention of initial physical properties of the formulation of the present invention.

For example, after one year of accelerated aging in an oven at about 150 F., the non-curable composition of the present invention was somewhat stilfer than originally. Otherwise, however, it was in a very good condition, generally commensurate with that first obtained.

The specimens were also exposed to direct weathering in Arizona for six months. The elongation was determined initially; after three months; and after six months of exposure. The formulation of the present invention had an initial elongation of 360 percent. After three months, its elongation was 300 percent and after six months, 270 percent. In contrast, the comparative formulation had: 390 percent initial elongation; 240 percent elongation after three months; and 160 percent elongation after six months.

In addition, the non-curable composition of the present invention showed no evidence of attack on wood backing to which it was attached after six months of outdoor exposure to the intense sun and dry atmosphere of the Arizona climate. In contrast, the comparative One Example 11 By way of demonstrating the use of a combination of two suitable plasticizers in a flashing composition according to the present invention, three compositions (designated A," B and C) were formulated containing the same essential polymer ingredients as that of Example I excepting to change the plasticizer in each of the consecutive formulations. Thus, in formu lution A, about 50 parts of n-butyl benzyl phthalate was employed as the only plasticizing ingredient. In B, about 50 parts of dicarbitol phthalate was utilized as a sole plasticizer. Formulation C was made with 50 parts total of a plasticizing mixture of about 20 parts of n-butyl benzyl phthalate and about 30 parts of dicarbitol phthalate.

Formulations A and B, when tested after oven exposure for about one month at about 150 F., showed some change in stiffness as compared to their original condition before the test. When the same plasticizers were combined (formulation C) and the formulation tested in an identical manner, the increase in stiffness was negligible.

A similar effect on the stiffness of flashing materials containing the same proportions of individual plasticizing compounds and combined plasticizing compounds was noted in the weight loss of the flashing materials prepared from identical compositions which. were age tested in an oven for approximately one month at about 150 F. The percentage Weight loss of each of the samples is shown in the following tabulation:

Percent Formulation Plasticizer weight loss A n-Butyl Benzyl Phthalate (50 parts) 6. 2 B Dicarbitol Phthalate (50 parts) .z 4. 5 C n-Butyl Ben yl Phthalato (20 parts) plus 3.1

Dicarbitol Phthalate (30 parts).

Example 111 Approximately equivalent proportions of the hereinafter specified ingredients were blended in a ribbon blender, transferred to a mixing type extruder, and thereafter extruded into a continuous sheet at a temperature of about 250 F.:

A similar sheet was made from the comparative composition of Example I. The extruded sheets were evaluated for influence of accelerated oven aging at 150 F. for days on physical properties. The percentage weight loss observed at regularly indicated intervals of the comparative formulation of Example I was 6 percent at 12 days; 8 percent at 24 days; and 13 percent at 90 days. The non-curable, plasticized composition according to the present invention was 4 percent at 12 days; 6 percent at 24 days; and 10 percent at 90 days. The significant decrease in percentage weight loss of the composition of the present invention as compared to the curable composition is readily apparent.

Since certain changes in practicing the invention may be made without departing from its spirit and scope,

7 it is to be understood, as readily appears, that all of the foregoing description and specification be interpreted as merely illustrative of the invention and in no sense limiting thereof excepting as it is delineated in the hereto appended claim.

What is claimed is:

In a construction having at least one joint required to be Weatherproofed, a flashing over said joint of the non-curable, resilient, thermoplastic sheet consisting essentially of: a copolymer of from about 80 to about 88 weight percent interpolymerized vinylidene chloride and from about 20 to about 12 weight percent interpolymerized acrylonitrile; from about 20 to about 80 parts by weight for each 100 parts by weight of said copolymer of a nonvolatile plasticizer for said copolymer; and from about 30 to about 100 parts by weight of a soft reinforcing carbon per 100 parts by weight of said copolymer.

References Cited by the Examiner UNITED STATES PATENTS Hanson et a1 260-855 Reilly 260-41 Kurtz et a1 26041 Reilly 260-41 Seymour et al. 26041 Tolman 260-31.8 Weaver et a1 260-31.4

Primary Examiner.

DANIEL ARNOLD, LEON I BERCOVITZ,

Examiners.

15 R. G. WEILACHER, I. A. KOLASCH, L. T. JACOBS,

Assistant Examiners.