BACKGROUND OF THE INVENTION

5 The present invention relates to a process for applying a composite film to a substrate object, to the composite film so applied, to a coated element formed thereby, and to an apparatus for carrying out the method- While not so limited, the present invention may typically 0 be employed to apply a decorative and/or protective composite film to concrete blocks, thereby to provide concrete blocks having reduced porosity, improved aes¬ thetics, and other desirable structural and/or design features. 5 U.S. Patent 3,687,771 to Meijer discloses a technique for applying a multi-layer protective or deco¬ rative film to concrete blocks. The film employed in the technique described in that patent employs a multi-layer film having an adhesive layer on one side which is used to 0 adhere the film to one of the outer surfaces of the block. A paper or plastic release plate is provided on the other side of the film. The release plate protects the composite film during manufacture, transportation, storage, and installation of the concrete block. It is removed after 5 the concrete blocks have been mortared into a wall or other structure.

However, it is now deemed preferable, for a variety of reasons, to not only apply a composite film to one exposed surface of the concrete block, but also to a 0 small adjacent portion of the sides of the concrete block adjacent the exposed surface. This is difficult or impossible with the composite film disclosed in the '771 patent. Particularly, the presence of the release plate increases the thickness of the composite film to the point 5 that the only reliable way of folding the composite at the edges of the exposed face of the concrete block is to heavily score the film along desired fold lines corre¬ sponding to the concrete block edges. This weakens the

composite film at the exposed edges of the block and may lead to a failure of the film in these areas.

Further, the technique of the *771 patent employs a resilient blanket under the block and film against which the composite film is pressed by the weight of the concrete block. Such an arrangement may not apply sufficient pressure to the film at the edges of the exposed surface of the concrete block to ensure dependable bonding of the film. And, such a resilient blanket is not capable of bonding the composite film to the portions of the sides of the concrete block adjacent the exposed surface.

Other patents relating to film coating of concrete blocks or other structural elements include U.S. Patent 3,145,502 showing the application of glass rein- forced plastic to a cement block; U.S. Patent 3,449,880 showing the bonding of a prefabricated plastic or metal pan to a masonry block; U.S. Patent 3,660,214 showing a concrete block having a facing of brick partially embedded in a resin matrix applied to the block; U.S. Patent 3,660,954 showing a pan-shaped cap of glass reinforced plastic applied to a concrete block; and U.S. Patent 3,809,595 comprising a divisional application of U.S. Patent 3,660,214.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved process for attaching a composite film to a preselected surface of a substrate object, such as a concrete block, in which the composite coating may also be easily and reliably applied to portions of the substrate object adjacent the preselected surface.

It is another of the present invention to provide an improved apparatus for applying a composite film to a substrate object, such as a concrete block, having an improved means for selectively heating a portion of the substrate to a predetermined temperature and improved means for positioning the composite film onto the preheated surface.

A further object of the present invention is to provide such an apparatus by which the film can be applied to portions of the substrate object adjacent the preselect¬ ed surface of the substrate object. It is still a further object of the present invention to provide such an apparatus by which the application of the film can be carried out in an energy conserving and efficient manner.

It is yet another object of the present invention to provide such an apparatus that may, if desired, be rendered mobile and self sustaining so that it may be placed in use directly at a construction site to provide coated concrete blocks, thereby to eliminate costs of transporting the blocks elsewhere to apply the film. Another object of the present invention is to provide an improved composite film for application to substrate objects. The composite film can serve both protective and decorative functions.

Yet another object of the present invention is to provide a substrate object, such as a concrete block or other structural element, having a composite film applied thereto. Such a substrate object has numerous aesthetic and structural advantages, including a sealing of the surface of the object to prevent "salting out" or efflores- cence from salts that would otherwise migrate and appear on an untreated surface of the object. The composite film penetrates the pores of the surface to which it is applied, rendering it impervious to moisture. This maintains the insulating properties of the substrate object and reduces its susceptibility to spawling under freeze/thaw condi¬ tions. The enhanced aesthetic appearance of the substrate object of the present invention permits, in many cases, the use of economical products such as concrete blocks, in place of higher grade construction materials, such as face brick, cut stone, decorative panels or ceramic tiling. This reduces costs and enables utilization of locally available materials. The decorative and protective

features of the substrate object of the present invention permits use of such objects in applications heretofore using paints or the like and are particularly suitable for applications in which surfaces are exposed to or, cleaned with, acids or caustics.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be further understood by reference to the following detailed description thereof, taken in conjunction with the drawings. In the drawings: FIG. 1 is a perspective view of a concrete block substrate object having a composite film applied thereto; FIG. 2 is an exploded perspective view similar to FIG. 1 showing the substrate object and the composite film element; FIG. 3 shows a modification of the composite film element;

FIG. 4 shows a further modification of the composite film element suitable for use with a triangular substrate object; FIGS. 5-9 show various embodiments of a composite film element comprising, and employed in, the present invention;

FIG. 10 is a block diagram illustrating the process of the present invention; FIG. 11 is a perspective view showing an appa¬ ratus suitable for applying a composite film element to a substrate object, such as a concrete block;

FIG. 12 is a partial cross-sectional view showing the portions of the apparatus employed to apply the film to the sides of the substrate object; and

FIG. 13 is a perspective view showing a further embodiment of apparatus suitable for applying the composite film to a substrate object such as a concrete block. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to a detailed description of the present invention, FIG. 1 shows a substrate object having composite film element 30 applied thereto. While for

purposes of explanation, substrate object 20 is shown and described as an ordinary concrete block, it will be appreciated that the present invention is applicable to numerous other suitable substrates, such as solid concrete blocks, bricks, tiles, etc., any of which may be formed from a variety of materials.

As shown most clearly in the exploded perspective view of FIG. 2, concrete block 20 has face members 22 and 24 separated by a plurality of webs 26 forming cores 28 within the block.

Composite film element 30 may be applied to the exposed surface 32 of one of face members 22, 24, for example, face member 22. For this purpose, composite film element 30 includes region 34 that is coextensive with surface 32 of face member 22.

In accordance with the present invention, composite film element 30 also includes edge portions 36a-d that are peripheral to region 34. As hereafter described in detail, edge portions 36a-36d are bent at 90° to region 34 and adhered to the sides of face member 22, thereby to cover all or a selected portion of the sides of face member 22. To facilitate the application of peripheral portions 36a-d to face member 22, a composite film element 30 may be provided with corner notches 38, aligned with the corners of face member 22. Or, as shown in FIG. 3 illustrating composite film element 30a, the corners of the composite film member may be cut at an angle for similar purposes.

Further, the peripheral edge portions 36a-d may contain spaced notches 40 for preventing any wrinkles in the film from propagating along the edge of the film during folding, thereby ensuring even folding and a uniform bond. The notches also permit mortar or other such material to bond between adjacent blocks when same are formed into a structural element, such as a wall. As shown in FIG. 4, the present invention is not restricted to parallelepipedal substrate objects. FIG. 4 shows composite film element 30b of a triangular configura-

tion suitable for use with substrate object 20a, similarly of triangular configuration. Also as shown in FIG. 4, the notches in peripheral portions 36 may assume a triangular configuration or some other configuration, such as curved. Further, while FIGS. 1 through 4 show substrate objects having angular edges, it will be appreciated that such edges may be curved if desired.

FIG. 5 shows a composite film suitable for use as element 30 having an internal carrier layer 60 formed, for example, of spun-bonded polyester. Layer 60 may be formed of the material made and sold as Reemay No. 2024 having a weight of 2.15 oz./sq. yd. and exterior surfaces that have been converted by methods known in the art to be suitable for being bonded, coated, and/or printed. Other fibrous materials formed, for example, of glass, acrylic, or aramid, may be used as carrier layer 60.

A heat activated layer 62 is bonded to the lower surface of layer 60, when the composite film element is oriented as shown in FIG. 5, by extrusion, roller-coating, or other suitable method. Layer 62 may be formed of a polyamid or copolymer material, such as ethyl vinyl acetate (EVA) , or other suitable material. In the practice of the invention it will be found advantageous for adhesive layer 62 to have a melt flow index in the range of 6.5 to 20 (depending on the density of the substrate object 20 to which the composite film is to be applied) and a ball ring softening point high enough to prevent reactivation of layer 62 by environmental conditions after application to the substrate object. Heat activation temperatures involved in the application of the composite film element 30 to substrate object 20 may range from 65° - 208°F. for ethyl vinyl acetate and 280° - 325°F. for a polyamide material.

Layer 62 may, alternatively, comprise a heat reactive polymer containing an agent causing the layer to change from one having thermoplastic properties to one

having thermo-setting properties upon the application of heat.

A layer 64 of ink, paint, or the like, having a desired design or other decorative effect is applied to the upper surface of carrier layer 60. Layer 64 may be provided by conventional printing methods such as offset or rotogravure, flexography, or silk screening.

Finally, layer 64 is covered with a transparent protective film 66 that preferably also offers dimensional stability. Layer 66 may comprise a polyethylene coated polyester film, such as that made and sold by E.I. DuPont under the trademark "Mylar". Or, other materials, such as polycarbonate or acrylic, may be used for layer 64.

Composite film element 30 shown in FIG. 5 thus has a heat activated material on one exposed surface thereof and a protective, dimensionally stable laminating film on its other exposed surface.

FIG. 6 shows a simplified composite film element

30a comprised of a layer 62a of heat activated material which may be formed of the materials noted above in connection with layer 62 shown in FIG. 5. In a typical embodiment of composite film element 30a, layer 62a may be

16 mils, thick before application. Element 30a also includes an outer layer 66a. Layer 66a may be formed in accordance with the use to which the substrate object 20 to which it is applied is to be put. Thus, it may comprise a simple protective layer for heat reactive layer 62a. As such, it may be formed of a polycarbonate layer 4 mils thick. Layer 66a may also incorporate the decorative properties desired in the composite film element.

However, in many cases, the structure formed of substrate objects 20 does not require the protection provided by such a layer 66 or 66a. This may, for example, be the case in which substrate objects 20 are employed in the interior of a building. In such cases, the decorative properties of the composite film element may assume greater importance. In addition to the materials described above

as suitable for use in the exterior layer of composite film 30, layer 66a may be formed of polyurethane or a latex material. Further, it may be desirable to provide a composite film element on substrate object 20 that permits painting the structure formed of the objects with conven¬ tional methods and materials at some point during the life of the structure. The composite film element 30a shown in FIG. 6 in which the exposed surface of layer 66a has been treated to render it paintable may be used in such instanc- es.

In the composite film element 30b shown in FIG.7, carrier layer 60b is formed of a non-fibrous plastic web. For example, layer 60b may comprise a semi-rigid plastic sheet of, for example 3 - 8 mils thickness. If desired, plastic sheet 60b may incorporate the colors and/or designs desired for composite film 30b and may be extruded from any suitable material, such as polyvinyl chloride or methacry- late having the desired flexibility and bonding character¬ istics. A protective layer 66b is provided on the upper surface of layer 60b. A heat activated layer 62b is provided on the lower surface. As noted above, if the protection provided by outer protective layer 66b is not desired or required, as for example, when the block is used in an interior application, the layer 66 may be omitted. In the composite film shown in FIG. 8, heat activated layer 62c includes reinforcing fibers, as for example, formed of glass or carbon, that provide additional stiffness and body to the layer 62c. This enables layer 62c to function both as a heat activated adhesive layer and as a carrier for composite film element 30c. Outer layer 66c may be formed of a heat sealable acrylic or a polyvinyl fluoride material, both of which have excellent durability with respect to the weather and color retention, if colored. The durability properties of such materials avoid the need for a protective overcoating, such as layer 66.

In the composite film element 30d shown in FIG. 9, layer 66d may comprise a transparent or translucent

outer layer while layer 62d formed of a heat activated material may be pigmented to provide a simple and econom¬ ical colored composite film element.

If substrate object 20 is used outside, a UV inhibitor may be incorporated in one of the layers of film element 30.

Turning now to FIG. 10, that figure shows a flow diagram illustrating the process of the present invention for applying a composite film element 30 to a substrate object. FIG. 10 shows the basic steps for carrying out the process.

In step 100, the substrate object 20 is precon¬ ditioned. Specifically, the substrate object is warmed by heated air recovered from downstream steps in the process. This preconditioning/preheating step for substrate object 20 recovers heat that would otherwise be lost, thereby improving the efficiency of the process and reducing the energy demand.

The preconditioning or preheating step 100 is followed by a surface heating step 200 in which the surface or surfaces of substrate object 20, such as surface 32 and the adjacent side surfaces, that are to receive composite film element 30 are heated to the desired level, for example, above a temperature that will activate heat activated layer 62.

In a typical embodiment of the invention, the surface of substrate object 20 will be raised to 200° - 400° F. , although the use of lower temperatures is possi¬ ble. The heat penetration in the surface areas is on the order of 1/2 inch. The combination of the recovered heat preconditioning of the substrate and the selective heating of only the surfaces, or portions thereof, to be coated by the film element to the minimum depth required for satis¬ factory application of the composite film element provides a very efficient operation to the process and apparatus of the present invention.

In positioning step 300, composite film element 30 is appropriately positioned relative to the heated surface of substrate object 20 and is applied thereto with layer 62 in contact with the heated surface. The activa- tion of layer 62 by heated surface 32 tacks the element to the substrate object.

Thereafter, in step 400, the film is pressed on the heated surface. This includes both the pressing of region 34 of film element 30 to surface 32 of substrate object 20 and the pressing of peripheral portions 36a-d to the sides of the portions of substrate object 20 adjacent surface 32.

In setting or curing step 500, composite film element 30 and substrate object 20 are cooled to set or cure the film to the substrate object. The heat removed from substrate object 20 during cooling step 500 is employed to heat substrate object 20 in preconditioning step 100 to usefully employ this heat and increase the efficiency of the process. The process illustrated in FIG. 10 thus econom¬ ically produces a substrate object having a tough durable, protective coating which may incorporate a wide range of aesthetic aspects. It has been estimated that when operat¬ ing at a rate of coating four conventional concrete blocks per minute, the process requires only approximately 7200 watts of electrical energy for operation.

FIGS. 11, 12 and 13 show apparatus that may be employed to carry out the process described in FIG. 10 and above. Apparatus 800 shown in FIG. 11 incorporates a conveyor belt 802 suitable for moving substrate objects 20 generally from left to right, when viewed as in FIG. 11. Thus, substrate objects 20 are placed on the left hand end of conveyor 802 to pass, in seriatim, along conveyor 802 for discharge at the right hand end of conveyor 802. Conveyor 802 may intermittently move substrate object 20

through apparatus 800 in carrying out the operation of the apparatus.

A substrate object 20 placed on the left hand end of conveyor 802 first passes to preconditioning housing 804. Preconditioning housing 804 is connected by a duct 806 to housing 808 in which substrate objects 20 having a composite film element 30 applied thereto are cooled to set or cure the film element 30 to the substrate object 20. For this purpose, ambient air is drawn in openings 810 in housing 808 by a fan or other suitable means. The air passes over heated substrate object 20 and composite film element 30. The air is thus heated as the object and film element are cooled. The heated air is supplied through, opposite to the direction of movement of object 20, duct 806, to housing 804 to precondition or preheat the sub¬ strate object 20 positioned in housing 804. The air is discharged through openings 812 in housing 804.

Preheated substrate object 20 is then moved to heater 814. In heater 814, an electrical resistance radiant heater, a gas burner, or other suitable means, heats the surface, or surfaces, of the substrate object to which composite film element 30 is to be applied above the heat activation temperature of layer 62 of composite film element 30. For example, a radiant electrical heater 816, which may be a ceramic heater, may be employed to raise the surface temperature of substrate element 20.

Substrate object 20 then advances to positioning and application apparatus 818. Apparatus 818 contains a stack of composite film elements in the form shown in the exploded view of FIG. 2. The films are positioned with heat activated layers 62 facing downward. Mechanical fingers interleaved in the stack, or other suitable apparatus, allow the lowermost composite film element to be separated from the remainder of the stack and to be positioned on the heated surface 32 of substrate object 20 with the registration shown in FIG. 2. The stack may be lowered to substrate object 20 for this purpose so that

the film element 30 is brought into light contact with heated surface 32 of substrate object 20. The stack is then translated away from the substrate object. Or the element 30 may drop from the stack onto the object. The heated surface 32 of substrate object 20 causes heat activated layer 62 of the composite film to become active, retaining, or tacking, the composite film on the heated substrate object.

Substrate object 20 with composite film 30 so attached is then moved along conveyor belt 802 to pressing unit 822. Pressing unit 822 includes a hydraulic cylinder 824 or other means by which platen 826 may be applied to substrate object 20 carrying composite film element 30 with the desired amount of force. Platen 826 may be provided with a non-adhering resilient lower surface that contacts composite film element 30 and presses it into firm, even contact with surface 32 of substrate object 20. This applies region 34 of substrate 30 to surface 32 of sub¬ strate object 20. As shown in FIG. 12, the hydraulic cylinder or other operating means 824 for platen 826 passes through pressing plate 828. Pressing plate 828 is biased upward and rests on springs 830 mounted on the upper surface of platen 826. Pressing plate 828 may be retained in a unitary structure with respect to platen 826 by pins 832 passing through pressing plate 828.

Platen 828 contains hinged platen portions 834, two of which portions 834a and 834c are shown in FIG. 12. Platen portions 834 are fixed to curved arms 836 which bear on the underside of pressing plate 828. Curved arms 836 may be resilient. When pressing plate 828 is in a raised position due to springs 830, platen portions 834 lie loosely along the sides of platen 826. When pressing plate 828 is moved downward, as shown by the arrows in FIG. 12, platen portions 834 are pivoted downward to press composite film element 30 against the sides of substrate object 20, as shown in FIG. 12. This ensures that composite film 30

is also securely fixed to the side portions of substrate element 20 adjacent surface 32.

A plate 838 may be provided beneath conveyor 802 to receive the forces generated by platen 826 and pressing plate 828.

The heat of substrate object 20 causes heat activated layer 62 of composite film element 30 to become flowable. The pressure applied by platen 826 and platen portions 834 causes the heated and flowable heat activated layer 62 of composite film element 30 to wet the surfaces of substrate object 30 and to enter the pores of a sub¬ strate object such as a concrete block, thereby to achieve a secure, uniform, and lasting bond between the composite film element 30 and substrate object 20. The elements of pressing station 822 are provided with a relatively free fit so as to accommodate out of square and out of parallel surfaces encountered with conventional substrate objects, such as concrete blocks, and to permit the application of firm and even pressure by pressing unit 822 even when substrate object 20 is out of square or parallel by as much as a quarter of an inch over its 5 length.

While the positioning apparatus 818 and pressing apparatus 822 have been shown as separate elements in FIG. 11, it will be appreciated that they may be combined, at a single location if desired. This may be accomplished through the use of an indexing apparatus that initially indexes positioning means 818 over substrate object 20 and thereafter indexes pressing apparatus 822 over substrate object 20.

After composite film element 30 has been pressed on substrate object 20 by pressing apparatus 822, substrate object 20 is moved to housing 808 in which air, drawn in through openings 810, cools and cures the bond between composite film element 30 and substrate object 20. As noted above, the air, after passage over heated substrate

object 20, passes through tunnel 806 to housing 804 to preheat substrate objects 20 entering apparatus 800.

After cooling and curing, substrate object 20 containing composite film 30 is discharged from the right hand end of conveyor 802.

FIG. 13 shows a further apparatus 800A for applying a composite film element to a substrate object. Apparatus 800A has a compact L-shape rendering same portable so that it may be transported to, and employed directly at, a job site.

Apparatus 800A includes conveyor 850 suitable for moving substrate object 20 into the apparatus. The objects first enter a preconditioning tunnel 852 in which an object 20 is preheated by heat discharged from surface heating section 854. Surface heating section 854 may include appropriate heating elements to heat surface 32 of object 20. Air may be drawn into surface heat section 354 through louvers 856 and discharged through preconditioning tunnel 852 in the manner shown by the arrows in FIG. 13. Positioning section 858 is positioned downstream of surface heating section 854. Positioning section 858 includes an apparatus, such as that shown in FIG. 11, for applying a composite film element 30 to the heated surface of substrate object 20. Substrate object 20 containing composite film element 30 is then transferred to discharge conveyor 860. Conveyor 860 moves the structural element to pressing section 862 at which composite film element 30 is pressed on structural element 20, as, for example, by a means similar to that shown in FIG. 12. The completed structural element 20 containing composite film 30 is then discharged from the apparatus, as by conveyor 864.

The low energy requirements of the apparatus, the minimal number of steps required in the apparatus and process, and the low power demand enable the apparatus to be constructed in a compact manner so that it may be easily transported to, and operated at, a construction site. This

avoids the need to transport the substrate objects to another location for application of the film element. The selective heating of the substrate and the even pressing provided by the pressing unit produce a finished substrate object that is having a highly consistent and uniform properties.

It will be apparent from the foregoing that variations and modification may be made to the invention described above. It is intended to cover all such varia- tions and modifications as fall within the scope of the appended claims.