US3575779A - Membranes and laminates of chlorinated linear polyethylene - Google Patents

Abstract

NOVEL PLASTIC MEMBRANES AND MEMBRANE LAMINATES USEFUL IN ONE-PLY ROOFING SYSTEMS AND IN SIMILAR APPLICATIONS MAY BE PREPARED FROM CHLORINATED LINEAR POLYETHYLENE PLUS FILLER, STABILIZER AND PIGMENT. THE CHLORINATED LINEAR POLYETHYLENE COMPRISES A MIXTURE OF TWO LINEAR POLYETHYLENES OF DIFFERENT COMPOSITIONS AND THE STABILIZER IS A MIXTURE OF 3,4 EPOXY-6-METHYLCYCLOHEXYLMETHYL 1-3, 4-EPOXY-6-METHYLCYCLOHEXANECARBOXYLATE; 2-6DITERT-BUTYL-4-METHYLPHENOL, AND AN ALCOHOL SELECTED FROM THE GROUP CINSISTING ESSENTIALLY OF SORBITOL, PENTAERYTHRITOL AND MIXTURES THEREOF

Description

United States 3,575,779 MEMBRANES AND LAMINATES F CHLORI- NA'IED LINEAR POLYETHYLENE Wilbur F. Chapman, Convent Station, Charles J. Klasen, Dover, and James J. Malone, J12, Wayne, N.J., assignors to Allied Chemical Corporation, New York, N.Y. N0 Drawing. Continuation-in-part of application Ser. No. 446,0S1, Apr. 6, 1965. This application June 21, 1967, Ser. No. 650,574

int. Cl. 332%) 17/04; C08f 29/04 US. Cl. 16189 7 Claims ABSTRACT OF THE DISCLOSURE CROSS-REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of application No. 446,091 filed Apr. 6, 1965, now abandoned.

BACKGROUND OF THE INVENTION This application relates to plastic membranes and, more specifically, to plastic membranes for use in single ply roofing and in other applications for the protection of water-permeable mineral or organic surfaces against the deteriorating influences of the weather and for the enhancement of their appearance.

Built-up roof construction conventionally consists of the application to a suitable roof deck of bituminous cement, bituminous saturated felts for reinforcement, top pouring materials and a gravel or slag weather resistant protective surfacing. Specifications for a roof having a wood deck typically require applying over the deck one ply of sheathing paper, two nailed fifteen pound saturated felts and three cemented fifteen pound saturated felts; all bonded together and topped by pitch or asphalt and a surface covering of loose slag or gravel to protect against ultraviolet light and to permit foot traffic. The many separate steps inherent in constructing this multicomponent built-up roofing system contribute to high labor costs and lengthy application times.

Portective sheeting materials are also commonly employed to form waterproof seals between the difierent parts of a roofing structure. Such protective sheeting materials are commonly known as flashing and are applied by cutting and heat forming the sheathing material to such shape as may be required in the particular application. For example, the sheeting may be cut and formed about the base of a chimney, vent stack, roof ventilator, etc., to prevent seepage through the roof. It is similarly used at the junction of the roof deck and the main walls. Within the structure flashing is commonly used as a base mat for flooring such as ceramic tiles, etc., and also in conjunction with piping to prevent water seepage through the floors and frame. Such sheeting material may also be shaped to form expansion joints between the various sections of a structure.

A variety of materials have been proposed and used as flashing. Sheet metals such as copper, galvanized iron, aluminum and lead have been used in the past in large quantities as flashing. Disadvantages involved in the use of sheet metal flashing include the necessity for the cutting and shaping of the metal for the particular application. Generally, the sheet metals require very careful cutting to fit the structure and relatively high heats are required in shaping the metal. Applications in which metallic flashing may be used have also been limited because of the difiiculty in conforming it to complex structures, for example, when flashing is required for use in conjunction with corrugated roofs and siding. Further, the sheet metals are, of course, not self-sealing and therefore require the concomitant use of relatively large amounts of waterproof bonding agents to effect a satisfactory installation.

It has, therefore, been suggested that a one-ply plastic roofing system be substituted for the currently used multicomponent built-up roofing system. However, because of the requirement that a one-ply roof have the same 15 to 25 year life as a built-up roof, it has been extremely difiicult tofind a suitable plastic membrane. The terms one-ply roofing and single-ply roofing as used herein are synonymous.

It has also been proposed to use filled plastic sheet compositions as flashing to overcome the difficulties encountered with the use of sheet metals in this application. Such proposed compositions generally comprise a resin base combined with plasticzers and fillers and have been designed to be relatively easy to form into the more complex shapes required in certain applications. The formulation of these flashing compositions has not been entirely successful because of the properties which such compositions should have. Such properties include hardness, high tensile strength and elongation, low brittle temperature, modulus of elasticity, shrinkage and vola tility and good processa'bility. The compositions must also be compatible with commonly employed bonding agents such as pitch and asphalt, must be heat-formable at moderate temperatures and must be capable of withstanding exposure to the elements for indefinitely long periods of time without cracking, loss of properties or other deterioration.

SUMMARY OF THE INVENTION An object of this invention is to provide a factorymade, rigidly controlled novel plastic membrane for use in one-ply roofing systems. A further object is to provide a novel plastic membrane laminate for use in one-ply roofing systems. A still further object is to provide novel plastic membranes and membrane laminates which will be comparable to or better than a multi-ply built-up roof with respect to satisfying the stringent technical and economic requirements therefor. Another object is to replace conventional built-up roofing with a simple-toapply system. Further objects and advantages will become apparent from the description of the invention which follows in greater detail.

In accordance with the invention, a plastic membrane has been found comprising:

(a) chlorinated linear polyethylene; (b) filler;

(c) stabilizer; and

(d) pigment.

Suitable chlorinated linear polyethylene for component (a) may comprise either a single chlorinated polyethylene (e) as defined infra or a mixture of chlorinated polyethylenes (f) and (g) infra wherein (f) forms the major proportion of the chlorinated polyethylene mixture and (g) the minor proportion.

Chlorinated polyethylene (e) may suitably contain from 32-37% chlorine by weight, have a glass transition temperature of no higher than about -l C., an intrinsic viscosity ranging from about 2.1 to about 3.0 dl./ gm. in o-dichlorobenzene at 100 C., and a crystallinity of no greater than 1% as determined by differential thermal analysis.

Chlorinated linear polyethylene (f) may suitably contain from about 25 to about 40% by weight chlorine and have a glass transition temperature of no higher than about 15 C., an intrinsic viscosity ranging from about 1.0 to about 2.0 dl./gm. in o-dichlorobenzene at 100 C., and a crystallinity of no greater than 10% as determined by differential thermal analysis.

Chlorinated linear polyethylene (g) may suitably contain from about 30% to about 45% by Weight of chlorine and have a glass transition temperature of no higher than about 5 C., an intrinsic viscosity ranging from about 3.5 to about 4.8 dl./gm. in o-dichlorobenzene at 100 C., and a crystallinity of no higher than 1% as determined by differential thermal analysis.

Preferred ranges for the chlorine content and physical properties of polymers (e), (f) and (g), supra, are as follows:

For (e): from about 33 to 35% by weight chlorine; a glass transition temperature of no higher than -l5 C.; an intrinsic viscosity ranging from about 2.2 to about 2.6 dl./gm. in o-dichlorobenzene at 100 C.; and no detectable crystallinity and an ultimate elongation of l50600%;

For (f): from about 29% to about 35% by weight chlorine; a glass transition temperature of no higher than 15 C.; an intrinsic viscosity ranging from about 1.2 to about 1.8 dl./grn. in o-dichlorobenzene at 100 C.; and a crystallinity of no greater than 1%;

For (g): from about 36% to about 41% by Weight of chlorine; a glass transition temperature of no higher than C.; and an intrinsic viscosity ranging from about 3.8 to about 4.8 dL/gm. in o-dichlorobenzene at 100 C.

The term intrinsic viscosity" is defined as the limit, at infinite dilution, of the specific viscosity divided by concentration expressed in grams of polymer per deciliter of solution. Specific viscosity is measured as efiiuent time for a given quantity of polymer solution from a standard pipet minus efiiuent time for an equal quantity of pure solvent, the remainder of the two effluent time quantities being divided by the efiiuent time for the equal quantity of pure solvent. Intrinsic viscosity can be determined, accordingly, by plotting the specific viscosity divided by concentration against concentration, using low concentrations, and extrapolating the resulting curve to zero polymer concentration. The intrinsic viscosities reported herein are determined in accordance with ASTM Test D-16016l, the units thereof being deciliters per gram (dl./gm.).

The glass transition temperature is a second order transition temperature and can be determined by plotting the stiffness modulus of a sample of material as a function of temperature, and the term is defined as the temperature at which the stiffness modulus of the sample 4 is equal to x10 p.s.i. (10 dynes/cm. The determination can be made in accordance with AST M Test Dl04361T. In efiect, the glass transition temperature is that temperature below which polymers become brittle. Above the glass transition temperature polymers are more flexible and rubbery.

Crystallinity is determined by differential thermal analysis as disclosed in the copending United States application of Carl R. Eckardt and William M. Bungo, Ser. No. 354,345, filed Mar. 24, 1964, now abandoned.

Although the chlorinated polyethylene as defined in (f), supra, is generally suitable without the concomitant use of chlorinated polyethylene (g) for making a plastic membrane for use in a one-ply roofing system, we have also found a significant problem involved in the use thereof. This problem is the difiiculty of commercially preparing a membrane formulation comprising chlorinated polyethylene (f) alone, in that such a membrane is not easily processable. We have determined that the lack of processability is due to a low hot strength value. Hot strength is defined as the ability of the unsupported sheet to retain its structural integrity under the strains and stresses of processing at elevated temperatures.

We have solved the problem of low hot strength by the use in conjunction with (f) of a minor proportion of the chlorinated polyethylene as defined in (g), supra. It is not understood why the inclusion of this specific chlorinated polyethylene (g) has this beneficial efiect, but it is clear that the hot strength problem cited is eliminated thereby.

The chlorinated polyethylene as defined in (f), supra, can suitably be present in amounts ranging from about 75 to about 95% by weight of the mixture of (f) and (g) and is preferably present in an amount ranging from about 88% to about 92% by weight.

The chlorinated polyethylene as defined in (g), supra, is always present in a minor proportion and can be present in amounts ranging from about 5% to about 25% by weight of the total weight of the mixture of (f) and (g) and is preferably present in amounts ranging from about 8% to about 12% by wei ht.

The chlorinated polyethylene as defined in (e), supra, is suitable for making a plastic membrane without the concomitant use of any other chlorinated polyethylene. Membranes prepared from chlorinated polyethylene (e), above, have adequate hot strength. However, a minor proportion of other chlorinated polyethylene may be added to (e), if desired.

All of the chlorinated polyethylenes used in this invention are derived from substantially linear, high density, high molecular weight polyethylene. The parent polyethylene can be produced by the gas phase polymerization of ethylene using silica/alumina supported magnesium dichromate together with aluminum triisobutyl as catalyst in accordance with British Patent No. 858,674 (as shown in Example 6 thereof). Suitable high molecular weight polyethylene can also be prepared in accordance with the process disclosed in United States Patents Nos. 2,825,721 and 3,110,709, by contacting ethylene at a temperature of from about to about 450 F., with a catalyst comprising chromium oxide, including a substantial amount of hexavalent chromium, associated with at least one other oxide usually selected from the group consisting of silica, alumina, zirconia and thoria.

Prior to chlorination, the polyethylene from which the various chlorinated polyethylenes are derived has a density ranging from about 0.935 to about 0.985 and a crystallinity of at least about 75% and customarily ranging from about 75% to about 85%, as determined by differential thermal analysis.

The preferred polyethylene for preparing chlorinated polyethylenes (e), (f) and (g) is produced in accordance with British Patent No. 858,674. The preferred polyethylone used for preparing chlorinated polyethylene (e) is of high weight average molecular weight, i.e. between about 250,000 and about 600,000 which corresponds to an intrinsic viscosity ranging from about 2.8 to about 5.2 as measured in Decalin at 135 C. The preferred polyethylene used for preparing chlorinated polyethylene (f), is of medium high weight average molecular weight, i.e., between about 50,000 and about 200,000, which corresponds to an intrinsic viscosity ranging from about 0.95 to about 2.5, as measured in Decalin at 135 C. The preferred polyethylene used for preparing chlorinated polyethylene (g) is of ultra high weight average molecular weight, i.e. between about 700,000 and about 5.0 million which corresponds to an intrinsic viscosity ranging from about 5.6 to about 12, as measured in Decalin at 135 C.

The intrinsic viscosities cited above are calculated in accordance with the method of P. S. Francis et al. from the kinematic viscosity of from about 0.05 to about 0.1 gram per 100 cc. solutions of polymer in Decalin using the equation:

wherein [1;] =intrinsic viscosity M=average molecular weight (I. Polymer Science, vol. 31, pp. 453466, September 1958).

The parent polyethylene suitable for preparation of chlorinated polyethylenes (e), (f) and (g) may optionally contain up to about 15% by weight of a C to C olefin comonomer, e.g. propylene, butene or the like, said parent polyethylene copolymer having a density of at least about 0.935.

Preparation of the chlorinated polyethylenes used in the composition of this invention is preferably accomplished by a two-stage aqueous suspension chlorination of the polyethylenes characterized above with the firststage chlorination being carried out on an aqueous slurry of the polyethylene polymer at a temperature below the crystalline melting point of the polymer, preferably at a temperature ranging from about 60 C. to about 130 C., and desirably at from about 90 C. to about 110 C., until at least about and preferably from about 7% to about 25%, by weight of chlorine has been introduced into the polymer. In the second stage, the chlorination is continued in the aqueous slurry at a temperature main tained above the crystalline melting point of the ethylene polymer until the desired total amount of chlorine is added. Second-stage chlorination temperatures are maintained above about 135 C. and preferably in the range of from about 140 C. to about 150 C. (the secondstage chlorination is carried out at temperatures above the crystalline melting point of the polymer for a time sufficient to add from about 5 to about 10% chlorine by weight) until at least a total of 25% chlorine has been added to the polymer, and the chlorination then continued at a lower temperature, e.g., at from about 100 C. to about 120 C., until the desired total amount of chlorine has been added.

The chlorinated polyethylenes used in this invention can be readily prepared by the above two-stage chlorination process and have a crystallinity of no greater than about 1%. Where chlorinated polyethylenes having a crystallinity of greater than 1% are desired, a temperature below the crystalline melting point of the ethylene polymer, as referred to in the first-stage chlorination, above, is maintained throughout the chlorination process.

Also see the copending United States application of Barton et al., Ser. No. 389,492, filed Aug. 13, 1964, now U.S. Patent No. 3,345,315.

Depending upon end use, i.e., the brittle temperature, elongation and stiffness or other properties required of the membrane; fillers can be added to the chlorinated polyethylene in amounts ranging from as low as parts to as much as 300 parts per hundred parts of (e) or of a mixture consisting of (f) and (g). Thus, for a roofing membrane from about 150 parts to about 200 parts of filler per hundred parts of polymer is in the preferred range, whereas a highly extensible membrane suitable for flashing above vent stacks would have a lower filler content, i.e., from about parts to about 75 parts of filler per 100 parts of polymer. Suitable fillers in judicious amounts extend the scope of application of the composition, and their foremost role is that of improving the properties of membranes (dimensional stability, for exam le) and lowering the cost of the composition. Some fillers, such as silicate hydrate, also seem to augment pigments in providing ultra-violet light protection.

Examples of fillers which can suitably be used include: silica or silica hydrate; silicates, such as calcium or other alkaline earth slilcates; materials containing silicates, e.g., infusorial earths, pumice or rock or asbestos powder; silicon carbide; sulfates or carbonates of alkaline earth metals; and other fillers such as coal, graphite, cryolite, asbestos fiber, sand, kaolin, ash and textile fiber or mixtures thereof.

Organic and mineral pigments can also be incorporated into the composition. Examples of suitable pigments include titanium dioxide, carbon black, antimony trioxide, phthalocyanines and the like. The pigments may be used alone or in combination. The amounts used can range from about 2 parts to about 50 parts of pigment per 100 parts by weight of the polymer. For black colored membranes about 5 parts of carbon black was found to be satisfactory, while opaque membranes may be obtained by the use of from about 28 to about 38 parts by weight of titanium dioxide per 100 parts by weight of polymer. Small amounts of other pigments maye be combined with the titanium oxide to achieve pastel shades. In addition to their primary function as colorants, pigments such as titanium oxide and carbon black act as effective screening agents against the deteriorating influence of ultra-violet light and afford excellent protection for the chlorinated polyethylene system. Additionally, carbon black is an outstanding reinforcement agent for chlorinated polyethylene. Some pigments, such as carbon black can function both as a filler and as a pigment, if desired.

A stabilizer is necessary in the membrane formulation in order to provide resistance to the heat which arises during the processing of the formulation into a membrane. The stabilizer also acts as an antioxidant for the formulation. Suitable stabilizers include Epoxide 201, the chemical composition of which is 3,4epoxy-6-methylcyclohexylmethyl 3,4 epoxy 6 methylcyclohexanecarboxylate; Ionol, 1 the chemical composition of which is 2,6di-tert butyl-4-methylphenol; sorbitol and pentaerythritol and mixtures thereof. The stabilizer can be present in a minor proportion, i.e., in amounts ranging from about 1 to about 5% of the total 'weight of the formulation.

1 A typical process for preparing a membrane is as folows:

Selected amounts of the components (a) through (d) are dry-blended and masticated on a rubber mill or in a conventional internal type mixer such as a Banbury mixer. The mix is then calendered in a conventional apparatus, e.g., an inverted L four-roll unit such as that supplied by the Farrell Corporation of Ansonia, Conn. Membranes having a thickness ranging from about 4 to about 75 mils can be prepared by this process. Whenever it is desired to laminate the plastic membrane to a flexible backing material, such as rubberized asbestos felt, the calendering and laminating operations can be done simultaneously on a calender.

The novel membranes of this invention can be from about 4 to about 75 mils in thickness and have an ultimate elongation of better than 200%; a tensile strength of better than 900 pounds per square inch; a brittle point 1 Registered trademark of Shell Chemical Corporation.

of below 12 C.; and a tear resistance of better than 150 pounds per inch of width.

In comparison with other commercially competitive polymers such as polyisobutylene, chlorosulfonated polyethylene, polyvinyl chloride and polyvinyl fluoride with respect to their use in plastic membranes in a one-ply roofing system, the chlorinated polyethylene as defined above has been found to be comparable to or better than the aforementioned competitive compositions With respect to providing membranes with the following desirable properties: weatherability, e.g. resistance to oxidation; colorability, i.e. the chlorinated polyethylene membrane can be colored white or any other color; water and fire resistance; elastic properties, flexibility at low temperatures (embrittlement is no problem), heat, light, abrasion, pressure, chemical, grease and oil resistance; and filler loading. Plasticizers are not necessary for the preparation of a plastic membrane from the chlorinated polyethylene and therefore the membrane is not susceptible to degradation caused by material migration, e.g. bleeding, leaching out and volatilization of the plasticizer.

The membranes prepared as described above may be utilized either alone or in the form of laminates of the sandwich or single backing sheet type. In the former instance, the membranes are used to sandwich, using heat and pressure, an intervening layer of material such as glass scrim, i.e. a matted or woven fiber glass cloth which serves as a reinforcement, such as Victor S229. A suitable laminating pressure is about 80 p.s.i.; a suitable laminating temperature is about 250 F. Adhesives can be used to make a sandwich with a great variety of other substances, such as asbestos felt or Masonite. The aforementioned glass scrim sandwich differs somewhat from most sandwiches because the fibers of the open weave glass cloth are at least partially encapsulated by the chlorinated polyethylene when heat and pressure are applied. If desired, the scrim may be laminated to only one sheet of plastic membrane rather than incorporated into a sandwich. The use of scrim in this manner affords laminates wherein the plastic membrane serves as the upper surface of the laminate and the scrim serves as the under surface or backing for the plastic membrane. In view of the partial encapsulation of the scrim, the line of demarcation between the plastic membrane and the scrim is not as distinct as, for example, when other types of backing such as absestos felt is used.

Asbestos felt impregnated with neoprene can likewise be laminated to the chlorinated polyethylene membrane by the hot-press method. This chlorinated polyethylene/ asbestos felt single backing sheet laminate has been found to be excellent for use in one-ply roofing systems. While the term one-ply roofing would in the strictest sense only be properly applied to the unlaminated plastic membrane, for practical purposes laminates and sandwiches are oneply since the roofer handles only a single sheet during installation. Other materials which can be laminated to the chlorinated polyethylene membrane of our invention are polyvinyl chloride, kraft paper, Masonite, particle board, plywood, cotton cloth, aluminum, insulation board, urethane foam, various foils such as aluminum foil, etc., and in all cases good bonds are obtained by the use of heat and moderate pressure either alone or in conjunction with an adhesive.

The long term performance advantages of the chlorinated polyethylene membrane for use in a one-ply roofing system and with regard to the properties heretofore mentioned, include high durability and weather resistance, which is predictable by tests of exposure to concentrated ultra-violet rays, water and water vapor; extreme flexibility as indicated by the extensibility of the unsupported sheet (350 to 450% before rupture using an Instron Tester); good low temperature properties as indicated by a brittle point below F. (12 C.); and resistance Registered trademark of Masonite Corporation.

to flame spread, such that it should be eligible for the Underwriters Laboratory Class A rating for roofing applied to noncombustible decks. Resistance of the membrane to flame spread may be further enhanced by the concomitant use of an asbestos felt backing, i.e. use of a membrane/ asbestos felt laminate. In addition, color can be an integral part of the chlorinated polyethylene membrane, and it has been found that virtually any colorability requirements can be readily met. A wide color range can be obtained by proper pigmentation to improve the appearance of roofs and other protected surfaces. Opaque white and pastel shades are especially preferred when reflection of solar heat is important to keep interiors cool and reduce the load on air-conditioning systems. It has been further found that proper application of this membrane in the one-ply system assures freedom from blisters, cracks and other defects commonly associtated with builtup roofing structures and that any damage areas which might develop initially or in service can easily be repaired simply by application of adhesive and a section of new membrane.

Other advantages of a one-ply roofing system, especially the chlorinated polyethylene one-ply roofing system of this invention, are as follows:

There are considerably fewer handling problems, e.g. a chlorinated polyethylene membrane rubberized asbestos felt laminate Weighs approximately 50 to 60 pounds per square feet covered inclusive of adhesives and tapes, whereas typical built-up roofing materials weight from 500 to 600 pounds per 100 square feet of roof covered. There are also fewer possibilities of error in application because of the fewer steps involved in one-ply construction. Policing in order to assure proper application is more easily effected. A cold adhesive system can be used in one-ply roofing which eliminates the hazards and heavy equipment associated with the use of hot asphalt or pitch. The high tensile and tear strength of the membrane lessens damage during handling, application and service. There are lower installation costs because of the fewer handling steps involved. Also, a shorter time is required to close in the roof.

A typical construction of a one-ply roofing system using the chlorinated polyethylene membrane of our invention is carried out as follows:

An adhesive is applied over a clear dry roof deck made of plywood, monolithic concrete, steel or other suitable base material with a roller or other applicator. The membrane or laminate is rolled out on the adhesive and then either broomed or rolled to secure proper contact. The joints can be lapped with adhesive and, if desired, sealed with tape. The set-time depends on the adhesive used. Flashing is then applied as required to finish the roof Desirably, the adhesive employed in constructing this one-ply roofing system should have a high initial tack, be quick-setting, resistant to heat and moisture, have good aging characteristics, high solids content and be easy to apply. Three major types of adhesives can be employed, namely, the hot-melt type as exemplified by steep roofing asphalt; the water emulsion latex type; and the solventbased elastomeric compositions. Examples of adhesives by trade name and chemical composition are: Flintkote No. 746 adhesive (rubberized asphaltic water-based adhesive); Flintkote No. 231 adhesive (white latex adhesive); Rubber-weld 3004 (rubber-based contact adhesive); and 3M Adhesive EC 1282 (a synthetic rubber-based contact adhesive in an organic solvent). There are a vast number of similar adhesives of the aforementioned types on the market and most of them are suitable and may be chosen to meet different requirements. Asphaltic hot melts can be used on all types of substrata, but for obvious reasons are suitable only when installing black or very dark colored membranes. Water-based adhesives require an absorbent substrata such as wood or concrete. Contact adhesives are satisfactory but somewhat difiicult to handle because of the immediate strong bond which permits no sliding of the membrane into place.

Further utility for the plastic membrane of this invention can be found as siding for various types of construction, as pit liners for materials such as brine and acid and as upholstery.

The invention can be more fully understood by reference to the following examples. All parts are parts by weight unless otherwise expressly noted.

Example 1 A plastic membrane was prepared having the following composition:

Parts Chlorinated polyethylene 1 90 Chlorine content =30% Intrinsic viscosity=1.5 Crystallinity: 1% Glass transition temperature=10 C. Chlorinated polyethylene 1 l Chlorine content=40% Intrinsic viscosity=4.0 Crystallinity: 1 Glass transition temperature=l0 C. Epoxide 201 (3,4-epoxy-6methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate) 3 Ionol (2,6-di-tertiary butyl-4-methyl phenol) 1 Pentaerythritol 1 Carbon black 3 Dioctyl phthalate 6.4 Atomic (calcium carbonate) 150 Prepared by first blending the components in a Henschel mixer, then masticating in a Banbury mixer at about 320 F. compound temperature, sheeting on a. Farrell rubber mill at 330-335 F. roll temperature and finally calenderiug on an inverted L four-r011 unit (manufactured by the Farrell Corporation of Ansonia, Conn Membrane thickness was varied at will from 25 to 40 mils, although thicker and thinner membranes could also be prepared.

Example 2 Three membranes were prepared according to the process of Example 1 without filler. Three different lots of the principal chlorinated polyethylene were used having slightly varying characteristics. Physical properties of the stabilized unfilled membranes are shown in Table 1 infra.

Example 3 A chlorinated polyethylene membrane was prepared as described in Example 1.

Table 2 shows various properties of the chlorinated polyethylene membrane of Example 1.

Table 3 shows various properties of the chlorinated polyethylene membrane of Example 1 as laminated.

Example 4- An open weave glass scrim (Victor S229) was sandwiched between 2 layers of the chlorinated polyethylene membrane of Example 1 using a temperature of 150 C. and a pressure of 80 pounds per square inch. The sandwich was 24 mils thick and was trimmed to a 36 inch width. For convenience of handling a 200 foot length of sandwich was wound on a 3 inch core for shipment to the job site. Part of the membrane was cut into 3 inch tape to provide sealing strip for joints.

Example 5 Flintkote No. 746 Adhesive, a rubberized asphaltic water-based adhesive, Was applied over a clean dry roof deck with a roller. The membrane of Example 1 was then rolled out onto the adhesive and broomed. Joints were lapped (2 inch) with adhesive.

Example 6 The construction of Example 5 was repeated using the membrane-glass scrim sandwich of Example 4.

The membrane and membrane-glass scrim sandwich were found to have all the properties and characteristics enumerated heretofore.

10 Example 7 A membrane was prepared similar to that in Example 1 except that different amounts of filler were used. Brittle temperature, elongation and ultimate tensile strength were determined. The results are shown in Table 4.

A membrane was prepared similar to that in Example 1 except that the amount of pigment was varied. Ultimate elongation, ultimate tensile strength, set at break, tear resistance and dimensional stability were determined. The results are shown in Table 5.

Example 8 An open weave glass scrim Victor S229) was used as backing for one layer of the membrane of Example 1 using a temperature of 150 C. and a pressure of pounds per square inch.

The properties of the laminate are shown in Table 6.

Example 9 A laminate was prepared as in Example 8 except that a neoprene impregnated asbestos (20 mils in thickness) was used as backing instead of the scrim. The properties of the resultant laminate are shown in Table 3.

Example 10 Hot steep roofing asphalt was applied over a previously adhered polyurethane foam roof insulation layer, and the laminate of Example 9 was applied asbestos side down. The edges of the 2 inch lap joints, glued to the underlying membrane, were covered adhesively with a 3 inch tape f the membrane-glass scrim laminate of Example 8.

Based upon experience with built-up roofing and other single-ply roofing such as polyisobutylene, polyvinyl fluoride, polyvinyl chloride and chlorosulfonated polyethylene sheeting or laminates, the chlorinated polyethylene membrane and sandwiches and laminates thereof were found to be comparable to or better than their built-up or single-ply roofing counterparts with respect to the enumerated properties and characteristics.

Example 11 A plastic membrane was prepared utilizing the same procedure and having the same composition as that of Example 1 except that a single chlorinated polyethylene was used. This chlorinated polyethylene had a chlorine content of 34%, an intrinsic viscosity of 2.4, a glass transition temperature of 16 C. and no detectable crystallinity. This membrane possessed all the desirable properties of the membrane of Example 1 and was equally suitable for use in roofing construction.

TABLE 1 Chlorine, percent 30. 3 30: 2 29. 9 Intrinsic viscosity 1.5 1. 5 l. 3 Glass transition temperature, 0.... 20. 0 23. 0 22. 0 Ultimate elongation, percent 655 695 750 Ultimate tensile strength, pounds per square inch 1, 365 1, 510 1,670 Set at break, percent 200 220 222 TABLE 2 The chlorinated polyethylene membrane of Example 1 Thickness, mils 25. Ultimate elongation, percent 260. Ultimate tensile strength, pounds per square inch 1,130. Tear resistance, ASTM D1004, pounds per inch. 257. Set at break, percent 43. Water vapor transmission, perms. Less than 1. Flexlng, cycles 2,000,000. Brittle point cold impact, C l4. Flame resistance Self-extinguishing. Solvent resistance. Very good. Chemical resistance Goodcan be modified with filler changes.

TABLE 3 The chlorinated polyethylene membrane of Example 1 The membrane Weight per 100 square ieet, pounds- 38. 1 Thickness, mils Ultimate elongation, percent" Elmendori tear at 71 F., grams Gurley stifiness at 71 F., grams Hardness Shore A-Z TearhASIM D1004, pounds per 1 The tear resistance of these laminates was above the testing capacity of the Elmendorf tester without additional calibrated weights.

TABLE 4 Ultimate Brittle Ultimate tensil Resin Filler temperaelongation, strength (parts) (parts) ture, 0. percent p.s.i.

TABLE Resin, parts 100 100 100 100 Pigment (carbon black), parts 5 25 40 50 Filler (calcium carbonate), parts. 150 150 150 150 Ultimate elongation, percent 415 340 260 270 Ultimate tensile strength, pounds per square inch 945 1, 150 1, 395 1, 480 Set at break, percent 90 91 77 82 Tear strength, pounds per inch. 264 290 304 Dimensional stability at 20 C 9, 3 7. 2 -5. 6

"Vulcan 9 is a registered trademark of Cabot Corporation, Boston, Massachusetts.

Various modifications will be apparent to one skilled in the art, and it is not intended that this invention be limited to the details in the specific examples presented by Way of illustration. Accordingly, the scope of the invention is limited only by the appended claims.

We claim:

1. A membrane comprising:

a mixture of chlorinated polyethylene consisting essentially of about 75% to 95% by weight of chlorinated linear polyethylene containing from about 25% to about 40% by weight chlorine and having a glass transition temperature of no higher than 15 C., an intrinsic viscosity ranging from about 1.0 to about 2.0 dL/gm. in o-dichlorobenzenc at 100 C., and a crytallinity of no greater than 10% and of about 5% to 25% by Weight of chlorinated linear polyethylene containing from about 30% to about 45% by Weight of chlorine; having a glass transition temperature of no higher than 5 C.; an intrinsic viscosity ranging from about 3.5 to 48 d1./ gm. in o-dichlorobenzcne at 100 C.; and a crystallinity of no greater than 1%;

a pigment;

12 and a stabilizer, said stabilizer comprising 3,4 cpoxy-6 methylcyclohexylmethyl 1-3, 4 epoxy 6 methylcyclohexanecarboxylic; 2-6-di-tert-butyl 4 methylphenol, and an alcohol selected from the group consisting of sorbitol, pentaerythritol and mixtures of said sorbitol and pentaerythritol.

2. A plastic membrane in accordance with claim 1 wherein said chlorinated linear polyethylene comprises a mixture having a major proportion of chlorinated linear polyethylene containing from about 29% to about 35% by Weight chlorine and having a glass transition temperature of no higher than -15 C., an intrinsic viscosity ranging from about 1.2 to about 1.8 dl./ gm. in o-dichlorobenzene at C., and a crystaliinity of no greater than 1%; and a minor proportion of a chlorinated linear polyethylene containing from about 36% to about 41% by Weight of chlorine and having a glass transition temperature of no higher than 10 C., an intrinsic viscosity ranging from about 3.8 to about 4.8 dl./gm. in o-dichlorobenzene at 100 C., and a crystallinity of no greater than 1%.

3. A plastic membrane sandwich wherein the upper and lower layers of said membrane sandwich are plastic membranes having the composition of the membrane of claim 1 and the intervening layer in said membrane sandwich is glass scrim.

4. A plastic membrane laminate wherein the upper layer of said laminate is a plastic membrane having the composition of the membrane of claim 1 and the lower layer of said membrane laminate is a member selected from the group consisting of glass scrim, foil and asbestos.

5. A roof construction comprising a plastic membrane in accordance with claim 1 adhesively affixed to a roof deck.

6. A roof construction comprising a plastic membrane sandwich in accordance with claim 3 adhesively affixed to a roof deck.

7. A roof construction comprising a plastic membrane laminate in accordance with claim 4 adhcsively afiixed to a roof deck.

References Cited UNITED STATES PATENTS 2,695,899 11/1954 Becker ct a1 260897C 2,851,389 9/ 1958 Lappala 264-171 2,913,449 11/1959 Hocrger et al. 26094.9 3,086,957 4/1963 Carter 260897C 3,244,774 4/1966 Kaupp et al. 260-897 3,282,910 11/1966 Klug ct a1 26094.9 3,314,841 4/1967 Romanin 161143X 2,268,162 12/1941 Myles et al 260897C 2,548,029 4/1951 Kurtz ct al. 161236 2,711,401 6/1955 Lally 260-4595 2,852,488 9/1958 Clark 260-459 2,930,726 3/1960 Jones et a1 161236 3,082,188 3/1963 Dietzler ct al 260-4595 3,227,781 1/1966 Klug et a1 260-897 3,409,706 11/1968 Frey et a1. 260-897 ROBERT F. BURNETT, Primary Examiner R. O. LINKER, JR., Assistant Examiner US. Cl. X.R.