EP1187717A1

EP1187717A1 - Extruded polystyrene foam insulation with high thermal resistance

Info

Publication number: EP1187717A1
Application number: EP00928526A
Authority: EP
Inventors: Ronald D. Deibel; Roy E. Smith; Jeffrey E. Bonekamp
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1999-05-19
Filing date: 2000-04-28
Publication date: 2002-03-20
Also published as: WO2000069624A1; CA2370863A1

Abstract

Adhere a composite facer to at least one, preferably both, primary surfaces of a foam panel or board to impart a combination of enhanced strength and long term thermal resistance to an insulating foam board. The composite facer includes a foam contact layer that provides strength, low elongation and abuse resistance and a barrier layer with low oxygen permeability.

Description

EXTRUDED POLYSTYRENE FOAM INSULATION WITH HIGH THERMAL RESISTANCE

This invention relates generally to laminated foam insulation boards having a foam core with spaced-apart and generally parallel major planar or primary surfaces, at least one of which has a facer adhered or bonded thereto. This invention particularly relates to such boards wherein the foam core comprises an alkenyl aromatic polymer such as polystyrene. This invention more particularly relates to such laminates that exhibit improvement, relative to the foam core alone, in at least one of stiffness, impact resistance, strength and resistance to bending and breaking together with an improvement in long term thermal resistance.

An improved laminated foam insulation board having enhanced strength and resistance to bending and breaking is disclosed in U.S. Patent No. (USP) 5,695,870, assigned to The Dow Chemical Company, the assignee of the present invention. The insulation board includes a panel of a plastic foam material and first and second thermoplastic facers adhered to both primary surfaces of the panel. Each facer has an ultimate elongation of less than (<) 200 percent (%) in both machine and transverse directions, a yield strength of at least (>) 7,000 pounds per square inch (psi)(48,400 (kilopascals kPa)) in both machine and transverse directions (MD and TD respectively), and a 1 percent secant modulus > 200,000 psi (1 ,380 megapascals (mPa)) in both MD and TD. The degree of adhesion between each of the facers and the foam panel is expressed as a peel strength of > 100 grams per inch (g/in)(39.4 grams per centimeter (g/cm)). Determine peel strength using a 180° peel test (American Society for Testing and Materials (ASTM) test D-903). Suitable films having the required properties include biaxially oriented polyolefin, aikenyl aromatic polymer, polyester, polycarbonate, acrylic polymer, and polyamide films having a thickness of from 0.35 to 10 mils (10 to 250 micrometers (μm)). The disclosed laminates exhibit significantly improved resistance to bending and breaking as compared with previously known insulation boards with facers that do not have the required elongation, yield strength, and one percent secant modulus. The laminated foam insulation boards of USP 5,695,870, like most previously known foam insulation boards, exhibit significant thermal resistance losses after manufacture as the facers are not substantially impervious to the passage of gas. As a result, air infiltrates into the cells of the foam panel and/or blowing agent migrates from the cells, diluting the insulating effect of the blowing agent which typically exhibits better resistance to heat flow than air. Thus, the infiltration of air into, and/or the escape of blowing agent from, the cells of the foam panel cause a substantial loss in the thermal resistance of the laminated foam insulation board. Typically the thermal resistance of laminated foam insulation boards is 15 to 20 percent lower six months after manufacture than it is at the time of manufactured.

Laminated foam insulation boards that comprise a plastic foam panel attached to a facer (at least one vinylidene chloride copolymer layer) that is substantially impervious to the passage of air have been found to retain higher thermal resistance over a longer period of time. However, such known laminated foam insulation boards do not exhibit the desired physical strength and abuse resistance.

The present invention is a laminated insulating foam board comprising a panel of a plastic foam material; and at least one facer film adhered to a primary surface of the panel, wherein the facer has an oxygen transmission rate of less than 10 cubic centimeters per 100 square inches of facer per 24 hour period per atmosphere of pressure (cc/100 in²-24 hrs-atm) (2.36 x 10^"9 cc/cm²-second-centimeter of mercury (cc/cm²-sec-cm Hg)), an elongation of less than 200 percent in both machine and transverse directions, a yield tensile strength of at least 7,000 pounds per square inch (48,400 kPa) in both machine and transverse directions, and a 1 percent secant modulus of at least 200,000 pounds per square inch (1 ,380 megapascals) in both machine and transverse directions.

The facer provides the laminated insulating foam boards with both a low gas transmission rate, especially to oxygen, and sufficient strength to resist bending and breaking.

Figure (FIG.) 1 is a perspective view of a foam laminate board of the present invention.

FIG. 2 is an enlarged, fragmentary, cross-sectional view of the board of FIG. 1 along a line 2-2.

FIG. 3 is an enlarged, fragmentary, cross-sectional view of the board of FIG. 1 along a line 2-2 as in FIG. 2, but with a composite facer. FIG. 1 simply shows a schematic illustration, in perspective view, of a foam laminate board 10 suitable for purposes of the present invention. FIG 1 also shows a section line 2-2 to better illustrate both a monolayer facer in FIG. 2 and a multilayer facer in FIG. 3. FIG. 2 shows a foam laminate board 10 that comprises a foam core 14 with a first facer 16 bonded to a one primary surface of foam core 14 and a second facer 18 bonded to a second primary surface of foam core 14. As shown in FIG. 2, the primary surfaces of foam core 14, and consequently first facer 16 and second facer 18, are spaced apart from, and generally parallel to, one another.

FIG. 3 shows an alternate foam laminate board 10' that comprises a foam core 14' with a first composite facer 15 bonded to one primary surface of foam core 14' and a second composite facer 17 bonded to a second primary surface of foam core 14'. The foam core 14' and the first and second composite facers 15 and 17 relate to each other in the same manner as their counterparts do in FIG. 2. First composite facer 15 includes a foam contact layer 16' and an external surface layer 20. Second composite facer 17 includes a foam contact layer 18' and an external surface layer 22.

While facers 16 and 18 may be formed from different polymer compositions, preferred results follow when they are formed from the same composition. Similarly, foam contact layers 16' and 18' preferably have the same composition and external layers 20 and 22 preferably have the same composition. Minimizing composition differences provides benefits such as ease of manufacture, reduced cost, and product uniformity. If desired, however, facers 16 and 18 and composite facers 15 and 17 may result from different polymer compositions. The laminated foam insulation board exhibits a substantially improved combination of physical strength, abuse resistance, and improved long-term thermal resistance as compared with known insulating foam boards.

Laminated foam insulation boards having desirable strength, abuse resistance, and long-term thermal resistance can be made by laminating a facer to both sides of a foam core. The facers exhibit a combination of low gas transmission rate, low elongation, and high tensile strength. More specifically, the facers exhibit an oxygen transmission rate (O2TR) of less than (<) 10 cc/100 in -24 hrs-atm (2.36 x 10⁹ cc/cm²-sec-cm Hg), an elongation of < 200 percent in both machine and transverse directions, a yield tensile strength of > 7,000 pounds per square inch (psi) (48,400 kilopascals (kPa)) in both machine and transverse directions, and a 1 percent secant modulus > 200,000 psi (1 ,380 megapascals (mPa)) in both machine and transverse directions. The required combination of properties enables the foam insulation board to withstand a variety of mechanical stresses such as impact, bending, and torsion, while also retaining high thermal conductivity over an extended period of time. The facers prevent or substantially reduce the likelihood of fracture propagation at the foam panel/facer interface, and are substantially impervious to the passage of gas.

The facer oxygen transmission rate (O₂TR) is preferably < 6 cc/100 in²- 24 hrs-atm (1.42 x 10^"9 cc/cm²-sec-cm Hg), more preferably < 2 cc/100 in²-24 hrs-atm (4.72 x 10^"10 cc/cm²-sec-cm Hg). The facer is preferably a composite of two or more layers, one of which provides a gas (oxygen) barrier. The gas barrier layer has a thickness that varies with the resin used to prepare the layer, but is sufficient to provide the composite with the O₂TR specified above. The desired combination of enhanced strength and improved long-term thermal resistance can be achieved using composite facers 15 and 17. Composite facer 15 includes a foam contact layer 16' that provides the elongation, tensile yield strength and 1 percent secant modulus properties specified above and a gas barrier layer 20 that provides the oxygen transmission rate performance specified above. Composite facer 17 includes foam contact layer 18' and gas barrier layer 22. Foam contact layers 16' and 18' are preferably identical to each other as are gas barrier layers 20 and 22.

Although foam board 10' includes composite facer 15 with a high strength, low elongation film layer 16' laminated directly to both foam panel 14' and gas barrier layer 20, skilled artisans understand that various modifications are possible without departing from the spirit and scope of the invention. For example, either or both of composite facers 15 and 17 can comprise additional layers, including a layer or layers between foam contact or high strength layer 16' or 17' and the respective gas barrier layers 20 and 22, a layer or layers between the foam panel and the high strength layer and/or oxygen barrier layer, and/or a layer or layers overlying the high strength layer and gas barrier layer. Such additional layers may be incorporated to provide additional functional or aesthetic qualities, with specific examples including additional thermoplastic layers, metal layers, kraft paper, fibrous layers, including woven and non-woven fabrics, and batts. Also, the high strength layer may be disposed between the foam panel and gas (especially oxygen) barrier layer, as illustrated, or, alternatively, the gas barrier layer may be disposed between the foam panel and the high strength layer, with or without additional layers. One or more adhesive layers, which may be the same or different from each other, may be used to bond the various layers of the facer together and/or to the foam panel. The high strength plastic layer may comprise any thermoplastic polymer as long as it meets the physical property criteria and can be effectively laminated to a foam panel The high strength plastic layer may comprise a polyolefin, alkenyl aromatic polymer, polyester, polycarbonate, acrylic polymer, or polyamide polymer Useful polyolefins include polyethylene and polypropylene Useful polyethylenes include high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE) Useful high strength plastic layers are generally biaxially oriented Preferred high strength plastic layers include biaxially oriented polyethylenes, polypropylenes, polyesters, polystyrene, or polyamides The high strength plastic film layer may be crosslinked or non-crosslinked The high strength plastic film layer optionally contains conventional additives such as inorganic fillers, pigments or colorants, antioxidants, ultraviolet stabilizers, fire retardants, and processing aids. The high strength plastic film layer typically has a thickness of from 0.35 mil (10 μm) to 10 mils (250 μm), and preferably from 0.5 (13 μm) to 3 mils (75 μm).

For biaxially oriented films, suitable thicknesses are from 0.35 mils (10 μm) to 10 mils (250 μm), and preferably from 0 5 mils (13 μm) to 1 mil (25 μm), whereas for non-oriented films, e.g., HDPE, suitable thicknesses are from 1.5 mils (38 μm) to 3 mils (75 μm), and preferably 1 5 mils (38 μm). The gas barrier layer of the composite facer may comprise any material that is substantially impervious to the passage of air More specifically, the gas barrier layer should exhibit an oxygen permeability of < 8 cc-mιl/100 ιn²-24 hrs-atm (4.8 x 10¹² cc-cm/cm²-sec-cm Hg), preferably < 3 cc-mιl/100 ιn²-24 hrs-atm (1 8 x 10¹² cc-cm/cm²- sec-cm Hg), and more preferably < 1 cc-mιl/100 ιn²-24 hrs-atm (6 0 x 10¹³ cc-cm/cm²- sec-cm Hg). Examples of suitable gas barrier layers include thermoplastic films having the required low oxygen permeability, and metal films formed or deposited on a primary surface of the high strength plastic film layer

Examples of suitable thermoplastic materials, which can be used for the gas, especially oxygen, barrier layer, include ethylene vinyl alcohol copolymers (EVOH) and vinylidene chloride (VDC) homopolymers and copolymers Examples of

VDC copolymers include copolymers that comprise VDC and at least one comonomer selected from unsaturated monomers copolymenzed therewith Suitable monomers for copolymeπzation with VDC include vinyl chloride, acrylonitnle, acrylic esters, and acrylic acids. Copolymers of VDC and vinyl chloride (known as "Saran") are also suitable for the oxygen barrier layer.

The gas barrier layer can be either coextruded with the high strength plastic film layer, or cast on the high strength layer, or laminated to the high strength film. Gas barrier layers comprised of EVOH are most preferably coextruded with a high strength plastic film layer, such as a polypropylene (PP) or HDPE film layer. Coextrusion provides excellent adhesion between the high strength layer and the gas barrier layer. VDC homopolymers and copolymers are most preferably cast on the high strength plastic film layer, such as by spraying a solution containing solubilized VDC homopolymer or copolymer onto the high strength plastic film layer and allowing the solvent to evaporate. Although it is preferred to form the gas barrier layer directly on the high strength plastic film layer, such as by coextrusion or casting, composite facers having the desired strength and low oxygen barrier transmission properties can be prepared by attaching a gas barrier layer to the high strength plastic film layer with an intervening adhesive layer. It is also possible to separately form a high strength plastic film layer and a gas barrier layer and subsequently thermally fuse the layers together, such as with application of heat and pressure. The gas barrier layer can be, and preferably is, < 1 mil (25 μm) thick, and more preferably < 0.5 mil (13 μm) thick, with suitable low gas (e.g. oxygen) transmission rates being achievable with films having a thickness of from 0.1 mil (2.5 μm) to 0.2 mil (5 μm).

A vacuum-deposited metal film provides an alternate gas barrier layer with a sufficiently low O₂TR. Although the metal film can be vacuum-deposited onto a film that does not have the desired high strength properties, and subsequently laminated to a high strength film, such as with adhesives or by thermal bonding by application of heat and pressure, preferred practice vacuum-deposits the metal film directly onto a primary surface of the high strength plastic film layer. Suitable vacuum- deposition techniques include sputtering, glow discharge, evaporation, vapor plating, and ion plating. On account of its excellent low O₂TR and relatively low cost, aluminum is a preferred material, for vacuum-deposition. Other suitable metals include antimony, silver, copper, nickel, beryllium, bismuth, germanium, hafnium, magnesium, niobium, tantalum, tin, titanium, tungsten, and zirconium. The thickness of the vacuum-deposited metal film typically ranges from 0.1 to 0.5 μm, preferably from 0.1 to 0.2 μm. Although biaxially oriented films are preferred for the high strength plastic film layer, non-oriented HDPE and PP films can be used as the high strength plastic film layer, provided that they have suitable thickness. In the case of non- oriented HDPE and PP, a suitable thickness is > 1.5 mils (38 μm). The (film or composite film) facer may be laminated to the present foam board by any conventional method known in the art. Useful lamination methods include hot roll lamination of a heat activated adhesive layer onto the facer. Another method is liquid coating or spraying coating of a hot melt adhesive or liquid-based adhesive onto the facer or foam board prior to lamination. An adhesive melt may also be extruded onto the facer or foam prior to lamination. The facer may also be coextruded with an adhesive layer, and subsequently laminated to the foam board.

The degree of adhesion between the facer and foam panel is sufficient to ensure adhesion during impact or bending. Separation or slipping between the facer and the foam panel at their interface negates the strengthening effect of the facer. The degree of adhesion between the facer and foam board is preferably such that any failure occurs within the foam rather than in the facer upon bending of the laminate board. The degree of adhesion is preferably high enough that part or all of the skin of the foam can be pulled off the remainder of the foam when the film is peeled off the foam. The adhesive must adhere to both the facer and the foam panel substrate. The degree of adhesion (or peel strength) is > 100 gm/in. (39.4 gm/cm) preferably > 250 gm/in. (98.5 gm/cm), according to the 180° peel test (ASTM D-903).

Suitable materials for use as adhesives or in adhesive layers include those adhesive materials known in the art as useful with plastic films and foams. They include polyolefin copolymers such as ethylene/vinyl acetate (EVA), ethylene/acrylic acid (EAA), ethylene/n-butyl acrylate, ethylene/methylacrylate, ethylene ionomers, and ethylene or propylene polymers grafted with an anhydride. Other useful adhesives include urethanes, copolyesters and copolyamides, styrene block copolymers such as styrene/butadiene and styrene/isoprene polymers, and acrylic polymers. The adhesives may be thermoplastic or curable thermoset polymers, and can include tacky, pressure-sensitive adhesives. The adhesive layer is preferably recyclable within the foam board manufacturing process. The adhesive material desirably has no significant negative impact upon the physical integrity or properties of the foam.

The foam panel or foam core stock of the present foam board may take the form of any insulation foam known in the art such as extruded polystyrene foam, molded expanded polystyrene (MEPS) foam, extruded polyolefin foam, expanded polyolefin bead foam, polyisocyanurate foam, and polyurethane foam.

The present invention is particularly useful with extruded polystyrene foam and MEPS foam. Such foams are readily recyclable and thermoplastic facers and adhesive materials are readily recyclable with the foams. Recyclability means the foams can be ground into scrap, which can be melted and processed with virgin polymer materials, blowing agents, and additives to form new foams. The facers also substantially enhance the strength of thin polystyrene foam boards useful in insulating sheeting applications, particularly those boards of thickness of from greater than zero inch up to and including 4 in (10.2 cm), desirably from 14 in to 4 in (0.64 centimeter (cm) to 10.2 cm).

Polystyrene foams may be derived from conventional alkenyl aromatic polymer materials. Suitable alkenyl aromatic polymer materials include alkenyl aromatic homopolymers and copolymers of alkenyl aromatic compounds and copolymerizable ethylenically unsaturated comonomers. The alkenyl aromatic polymer material may further include minor proportions of non-alkenyl aromatic polymers. The alkenyl aromatic polymer material may comprise one or more alkenyl aromatic homopolymers, one or more alkenyl aromatic copolymers, a blend of one or more each of alkenyl aromatic homopolymers and copolymers, or blends of any of the foregoing with a non-alkenyl aromatic polymer. Regardless of composition, the alkenyl aromatic polymer material comprises > 50, preferably > 70, wt percent alkenyl aromatic monomeric units, based on total polymer weight. Most preferably, the alkenyl aromatic polymer material comprises 100 wt percent alkenyl aromatic monomeric units. Suitable alkenyl aromatic polymers include those derived from alkenyl aromatic compounds such as styrene, alpha-methylstyrene, ethylstyrene, vinyl benzene, vinyl toluene, chlorostyrene, and bromostyrene. A preferred alkenyl aromatic polymer is polystyrene. Minor amounts of monoethylenically unsaturated compounds, such as C2-6 alkyl acids and esters, ionomeric derivatives and C_μ6 dienes may be copolymerized with alkenyl aromatic compounds. Examples of copolymerizable compounds include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, itaconic acid, acrylonitrile, maleic anhydride, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, vinyl acetate and butadiene. Preferred foams comprise substantially (i.e., > 70 wt percent), more preferably > 95 wt percent and most preferably entirely of polystyrene.

Extruded polymer foam preparation generally involves heating a polymer material to form a plasticized or melt polymer material, incorporating therein a blowing agent to form a foamable gel, and extruding the gel through a die to form the foam product. Heating the polymer material to a temperature at or above its glass transition temperature or melting point typically precedes blowing agent addition. Blowing agent incorporation into or admixture with a polymer melt material may use any means known in the art such as with an extruder, mixer, or blender. Mix the blowing agent with the polymer melt material at an elevated pressure sufficient to prevent substantial expansion of the polymer melt material and to generally disperse the blowing agent homogeneously therein. Optionally, blend a nucleator in the polymer melt or dry blend the nucleator with the polymer material prior to plasticizing or melting. Typical procedures cool the foamable gel to a lower temperature to optimize physical characteristics of the foam structure. Gel cooling may occur in the extruder or other mixing device or in separate coolers. Extrude or conveyed the foamable gel through a die of desired shape to a zone of reduced or lower pressure to form the foam structure. The zone of lower pressure is at a pressure lower than that in which the foamable gel is maintained prior to extrusion through the die. The lower pressure may be superatmospheric, subatmospheric (evacuated or vacuum), or at an atmospheric level.

Form MEPS foams by expanding pre-expanded beads that contain a blowing agent. Mold the expanded beads at the time of expansion to form articles of various shapes. Processes for making pre-expanded beads and molded expanded bead articles are taught in Plastic Foams, Part II, Frisch and Saunders, pp. 544-585, Marcel Dekker, Inc. (1973) and Plastic Materials, Brydson, 5th ed., pp. 426-429, Butterworths (1989), the teachings of which are incorporated herein by reference. Thermoplastic facer films, while particularly useful for lamination to polystyrene foam boards, also yield enhanced strength when laminated to polyisocyanurate and polyurethane foam boards. Barrier facers help to maintain the R-value of such boards in the same way as they do on polystyrene foam boards.

Prepare polyurethane and polyisocyanurate foam structures by reacting two preformulated components, commonly called an A-component and a B- component. The preformulated components comprise an isocyanate and a polyol. Polyurethane foam preparation involves a reaction between a polyol and an isocyanate on a 0.7:1 to 1 1 1 equivalent basis Polyisocyanurate foam preparation includes a reaction between a polyisocyanate and a minor amount of polyol to provide 0 10 to 0.70 hydroxyi equivalents of polyol per equivalent of polyisocyanate. USP 4,795,763, the teachings of which are incorporated herein, discloses useful polyurethanes and polyisocyanurates as well as their preparation.

Blowing agent selection is not critical to the present invention Blowing agents useful in making a foam board vary depending upon the composition of the foam and can include inorganic blowing agents, organic blowing agents and chemical blowing agents. Suitable inorganic blowing agents include carbon dioxide, argon, and water. Organic blowing agents include aliphatic hydrocarbons having 1-9 carbon atoms (C, ₉), C, ₃ aliphatic alcohols, and fully and partially halogenated C, ₄ aliphatic hydrocarbons. Particularly useful blowing agents include n-butane, isobutane, n- pentane, isopentane, ethanol, chlorod fluoromethane (HCFC-22), 1 ,1 -dιfluoroethane (HFC-152a), 1 ,1 ,1 ,2-tetrafluoroethane (HFC-134a), ethyl chloride, 1 ,1 -dιchloro-1- fluoroethane (HCFC-141 b), and 1 -chloro-1 ,1-dιfluoroethane (HCFC-142b), 1 ,1 ,1 ,3,3- pentafluoropropane (HFC-245 fa), 1 ,1 ,1 ,3,3-pentafluorobutane (HFC-365 mfc), cyclobutane, and cyclopentane. The present invention is particularly useful when the blowing agent has a thermal resistance greater than air. The foam board may have incorporated therein one or more additives such as inorganic fillers, pigments, antioxidants, acid scavengers, ultraviolet absorbers, flame retardants, processing aids, extrusion aids, and the like.

In addition, a nucleating agent may be added in order to control the size of foam cells. Preferred nucleating agents include inorganic substances such as calcium carbonate, talc, clay, titanium dioxide, silica, barium stearate, diatomaceous earth, mixtures of citric acid and sodium bicarbonate, and the like. The amount of nucleating agent employed may range from 0.01 to 5 parts by weight per hundred parts by weight of a polymer resin (phr) The preferred range is from 0.1 to 3 phr.

Suitable polystyrene foam densities range from 10 kilograms per cubic meter (kg/m³) to 150 kg/m³, preferably from 10 kg/m³ to 70 kg/m³ (ASTM D-1622- 88). The polystyrene foam average cell size ranges from 0.1 mm to 5 mm, preferably from 0.15 mm to 1.5 mm (ASTM D3576-77).

The polyisocyanurate foams and polyurethane foams have a density range of from 10 kg/m³ to 150 kg/m³, preferably from 10 kg/m³ to 70 kg/m³ (ASTM D- 1622-88). The polyisocyanurate foam and polyurethane foam average cell size ranges from 0.05 mm to 5.0 mm, preferably from 0.1 mm to 1.5 mm (ASTM D3576-77).

The polystyrene foams may be closed cell or open cell, but are preferably closed cell, more preferably with a closed cell content >90 percent (ASTM D2856-87).

The present foam board may be used to insulate a surface or an enclosure or building by applying the board to the same. Other useful insulating applications include in roofing, refrigeration, and the like.

The following examples illustrate, but do not limit the present invention. Unless otherwise indicated, all percentages, parts, or proportions are by weight.

Using extruded polystyrene foam panels having a thickness of 0.56 in

(14 mm), a density of 2 pounds per cubic foot (pcf) (32 kg/m³) and measuring 4 feet by 8 feet (1.2 meter (m) by 2.4 m) as foam cores, laminate facers to both sides of a foam core using an EVA copolymer adhesive to form laminated foam boards suitable for testing. While the polystyrene foam panels used in the examples all have the same R- value when measured on as-extruded foam, Table 2 below shows a discernible R- value drop-off for some laminates with an "initial" measurement taken at seven (± two) days and a further drop-off after aging for six months (± five days). The EVA copolymer has a vinyl acetate content of 18 wt percent, based on copolymer weight, a density of 0.95 g/cc and a melt index (ASTM D-1238) of 8.0 dg/min.

Physical property testing of the facers, both composite and monolayer, focuses upon yield tensile strength, ultimate elongation percentage and 1 percent secant modulus, all in accord with ASTM D-882. For composite facers, measure O2TR using a Mocon Ox-Tran model 10-50 oxygen permeability tester (ASTM D3985)after laminating the facer to the foam core. Table I summarizes physical property test results for composite facers.

Measure an initial R-value of each laminated foam board at seven (± two) days after extrusion and lamination and an aged R-value at six months (± five days) later using a Laser Comp model 304 heat flow meter and ASTM C-518. Table II summarizes thermal resistance or R-value measurements.

Subject the laminated foam boards to a "ball drop" test in order to evaluate resistance to bending and breaking. In this test, individually clamp each laminated foam board onto a 4 ft by 8 ft (1.3 m by 2.4 m) horizontal stud or building frame wall section with 16 in (41 cm) centers). Drop a 4.32 pound (1.96 kg) ball having a diameter of 3 inches (7.6 cm) from a height of 36 in (91 cm) onto the center of each laminated foam board midway between the 16 in (41 cm) centers. Examine the boards after the test to determine the extent of damage.

Use a "kneeling" test to simulate a ladder bearing a person leaning against a foam board attached to a vertically-erected frame wall or a person or persons kneeling on a foam board attached to a horizontally-disposed frame wall as the frame wall is being constructed.

In the kneeling test, allow several different individuals ranging in weight from approximately 100 to 200 pounds (45 to 100 kg) to kneel, crawl, or walk in sequence (one after the other) upon foam boards between the 16 in (41 cm) centers of a horizontally-disposed frame wall. Subjectively evaluate the physical integrity of the foam board and its resistance to bending and fracture on a 1 -5 scale (1 -fracture through board; 5-no damage). Test several samples of each foam board and average the results. To evaluate resistance to bending and breaking, subject the laminate foam boards to the "180° bend" test. In this test, manually bend 1 ft by 2 ft (30.5 cm by 61.0 cm) pieces of each foam board in half such that the board is bent back upon itself. Examine the foam board to see whether it breaks or not.

COMPARATIVE EXAMPLE (COMP EX)1 Prepare a 1.0 mil (25 μm) coextruded film comprising a 0.8 mil (20 μm) thick primary layer and a 0.2 mil (5 μm) thick adhesive layer on a conventional upward- blown film extrusion line at extrusion temperatures of 375°F to 400°F (191°C to 204°C). The primary layer comprises a blend of 85 wt percent LLDPE and 15 wt percent LDPE. The adhesive layer comprises a blend of 95 wt percent EVA copolymer and 5 wt percent silicon dioxide (Siθ2) in the form of a concentrate (15 wt percent SiO² in LDPE) as an antiblocking concentrate. Laminate the coextruded film to both primary surfaces of an extruded polystyrene foam board (14 mm thick) with a hot roll laminator operating at 375°F (191 °C) with the adhesive layer in contact with the primary surfaces. The laminate exhibits a peel strength of 250 gm/in. (98.5 gm/cm). The coextruded film has physical properties as set forth in Table 1.

COMP EX 2 Extrusion coat a 1.0 mil (25 μm) biaxially oriented polypropylene film (OPP) with a uniform 0.4 mil (10 μm) EVA adhesive layer across the OPP film. Thermally laminate the coated film as in Comp Ex 1. The peel strength is > 300 gm/in. (118.2 gm/cm). The film has physical properties as set forth in Table 1.

EX 3 Prepare a non-oriented composite facer by coextruding HDPE (1 mil (25 μm) thick) and EVOH (0.1 mil (2.5 μm) thick). Laminate the coextruded film and to both primary surfaces of an extruded polystyrene (PS) foam as in Comp Ex 1 , but use an intervening EVA layer (0.4 mil, (10 μm) thick).

EX 4 Prepare a composite facer in substantially the manner and set forth in EX 3, but use a metallized (0.2 μm thick aluminum layer) 0.5 mil (13 μm) thick biaxially oriented polyethylene terephthalate film that is extrusion coated with an EVA layer instead of the HDPE/EVOH/EVA film of EX 3. Laminate the composite facer to each of the major surfaces of a PS foam in substantially the same manner as set forth in COMP EX 1. EX 5

Prepare a composite facer by coextruding PP and EVOH. Biaxially orient the coextruded film. The PP layer has a thickness of 0.5 mil (13 μm) and the EVOH layer has a thickness of 0.2 mil (5 μm). Laminate the composite facer film to each of the major surfaces of a polystyrene foam board in substantially the same manner as set forth in COMP EX 1.

EX 6 Prepare a composite facer by casting a polyvinylidene chloride (PVDC) film onto a 0.7 mil (18 μm) thick OPP film. Cast the PVDC film by spray coating a major surface of the OPP film with a solution containing solubilized PVDC polymer, and allowing the solvent to evaporate and to leave a PVDC film with a thickness of 0.2 mil (5 μm). Extrusion coat an EVA adhesive layer onto the OPP side of the composite facer as in Comp Ex 2 and laminate the coated composite facer to an extruded PS foam board, also as in Comp EX 2.

Table 1 shows the physical properties of the facers of COMP EX 1 and 2, and EX 3-6, and Table 2 shows the R-values for the laminated foam boards of COMP EX 1 and 2 and EX 3-6.

The laminate foam boards of COMP EX 2 and EX 3 all withstand five consecutive ball drops without suffering fracture or penetration, whereas the laminate foam boards of COMP EX 1 fracture easily by impact of the ball. In the "180° bend" test, the foam boards of COMP EX 2 and EX 3-6 all bend without breaking, whereas the foam boards of COMP EX 1 break prior to completing the 180° bend.

In the "kneeling" test, the foam boards of COMP EX 1 average a rating of 2 and 3, respectively, while those of COMP EX 2 and EX 3-6 average between 4 and 5 and exhibit little or no damage.

While the examples and specification provide specific details about embodiments of laminate foam boards of the present invention, skilled artisans understand that the present invention may be modified by various changes while still being fairly within the scope of the novel teachings and principles herein set forth. Such changes may stem from, for example, a manufacturer's choice of process conditions, materials or both.

The laminate foam boards of COMP EX 2 and EX 3 all withstand five consecutive ball drops without suffering fracture or penetration, whereas the laminate foam boards of COMP EX 1 fracture easily by impact of the ball.

In the "180° bend" test, the foam boards of COMP EX 2 and EX 3-6 all bend without breaking, whereas the foam boards of COMP EX 1 break prior to completing the 180° bend.

In the "kneeling" test, the foam boards of COMP EX 1 average a rating of 2 and 3, respectively, while those of COMP EX 2 and EX 3-6 average between 4 and 5 and exhibit little or no damage. While the examples and specification provide specific details about embodiments of laminate foam boards of the present invention, skilled artisans understand that the present invention may be modified by various changes while still being fairly within the scope of the novel teachings and principles herein set forth. Such changes may stem from, for example, a manufacturer's choice of process conditions, materials or both. TABLE 1 PHYSICAL PROPERTIES OF FACERS

^* = cc/100 in²-24 hrs-atm / cc/cm²-sec-cm Hg ^** Ultimate percent Elongation (Average)

TABLE 2

The R-value data of Table 2 shows that Ex 3-6 begin with higher R- value than either Comp Ex 1 or Comp Ex 2. The R-value data also show that the laminates of Ex 5 and 6 retain their R-value after six months, the laminates of Ex 3 and 4 remain higher than the starting R-values for Comp Ex 1 and 2. Both Comp Ex 1 and Comp Ex 2 evidence an R-value drop over the six month period.

The combined data of Tables 1 and 2 show that, or balance, the foam laminate boards of Ex 3-6 outperform those of Comp Ex 1 and 2. Similar results are expected by varying one or more of the materials and parameters presented in the Example. The above disclosure provides simple teachings of possible variations.

Claims

WHAT IS CLAIMED IS:

1. A laminated insulating foam board comprising: a panel of a plastic foam material; and at least one facer adhered to a primary surface of the panel, wherein the facer has an oxygen transmission rate of less than 10 cubic centimeter per 100 square inches of facer per 24 hour period per atmosphere of pressure (cc/100 in²-24 hrs-atm) (2.36 x 10^"9 cubic centimeters per square centimeter per second per centimeter of mercury (cc/cm²-sec-cm Hg)), an elongation of less than 200 percent in both machine and transverse directions, a yield tensile strength of at least 7,000 pounds per square inch (48,400 kilopascals) in both machine and transverse directions, and a 1 percent secant modulus of at least 200,000 pounds per square inch (1 ,380 megapascals) in both machine and transverse directions.

2. The laminated insulating foam board of Claim 1 , wherein the facer is a composite facer film including (i) a high strength plastic film layer having an elongation of less than 200 percent in both machine and transverse directions, a yield tensile strength of at least 7,000 pounds per square inch (48,400 kilopascals) in both machine and transverse directions, and a 1 percent secant modulus of at least 200,000 psi (1 ,380 megapascals) in both machine and transverse directions; and (ii) a gas barrier layer having a normalized oxygen permeability of less than 8 cc-mil/100 in²-24 hrs-atm (4.8 x 10^'12 cubic centimeters-centimeter/square centimeter-second- centimeter of mercury (cc-cm/cm²-sec-cm Hg)).

3. The laminated insulating foam board of Claim 2 wherein the high strength plastic film layer is an unoriented high density polyethylene film or an unoriented polypropylene film, the film having a thickness of at least 1.5 mils (38 micrometers).

4. The laminated insulating foam board of Claim 2, wherein the high strength plastic film layer is a biaxially oriented polypropylene film, a biaxially oriented polyethylene terephthalate film, or a biaxially oriented nylon film.

5. The laminated insulating foam board of Claim 2 in which the gas barrier layer is an ethylene/vinyl alcohol copolymer film, a polyacrylonitrile film, a propylene/vinyl alcohol film, is a polyvinylidene chloride film, a vinylidene chloride/vinyl chloride copolymer film, a polyvinylidene chloride/polyvinyl chloride/methyl methacrylate terpolymer film, or a vacuum-deposited metal film.

6. The laminated insulating foam board of Claim 5, wherein the metal film is aluminum film.

7. The laminating insulating foam of Claim 2, wherein the gas barrier has dispersed therein an amount of plate-like filler sufficient to create an oxygen barrier.

8. The laminated insulating foam board of Claim 1 in which the panel is comprised of extruded polystyrene foam, molded expanded polystyrene foam, or a polyisocyanurate foam.

9. The laminated insulating foam board of Claim 1 , wherein an adhesive layer bonds the facer film to the panel.

10. The laminated insulating foam board of Claim 1 , wherein the panel has a thickness within a range of from ^ΛA inch (6.4 millimeters) to 4 inches (100 millimeters) thick.

11. The laminated insulating foam board of Claim 1 , wherein the facer film has a thickness of from 0.35 mils (10 micrometers) to 10 mils (250 micrometers).

12. The laminated insulating foam board of Claim 1 , wherein the panel of plastic foam material has a thickness of from greater than zero inch up to and including 4 inches.

13. The laminated insulating foam board of Claim 1 , wherein the oxygen transmission rate is less than 3 cc/100 in²-24 hrs-atm (7.08 x 10^"10 cc/cm2- sec-cm Hg).

14. The laminated insulating foam board of Claim 1 , wherein the oxygen transmission rate is less than 1 cc/100 in²-24 hrs-atm (2.36 x 10^'10 cc/cm2- sec-cm Hg).