US 20080010924 A1
A building product which includes a hollow extrudate, unitary reinforcing ribs resisting collapse of the hollow extrudate and, in an embodiment, an exterior surface comprises a low gloss, textured pattern having a gloss level of less than about 50 on a 60° glossmeter, in which the textured pattern extends for about 2-20 feet. Methods and an apparatus for manufacturing such products are also provided by this invention.
1. A building product comprising:
a unitary extrudate having unitary reinforcing ribs;
a continuous length pattern of surface topography features embossed in exterior sides of the unitary extrudate, wherein the sides are supported to resist collapse thereof while heat and forces are applied to the sides during embossing; and
the sides form a hollow unitary extrudate with the ribs extending between the sides.
2. The building product of
3. The building product of
4. The building product of
5. The building product of
the unitary ribs comprising first ribs on a first side of the extrudate and second ribs on a second side of the extrudate;
the sides being joined by a unitary hinge, wherein the sides are pivoted and closed together to form the hollow unitary extrudate; and
the first ribs interlock with the second ribs.
6. The building product of
7. The building product of
the unitary extrudate comprising a polymeric unitary hollow member either with a capstock layer or without a capstock layer, and with or without streaker material in the unitary extrudate.
8. The building product of
9. The building product of
one or more unitary ribs in the hollow interior portion.
10. The building product of
11. The building product of
12. The building product of
13. The building product of
14. A method of making a building product, comprising:
extruding a unitary extrudate;
forming unitary reinforcing ribs on the unitary extrudate;
embossing a continuous length pattern of surface topography features in exterior sides of the unitary extrudate; and
supporting the sides to resist collapse thereof while heat and forces are applied during embossing.
15. The method of
supporting the interior of the extrudate by mandrels during embossing to resist collapse thereof.
16. The method of
extruding the unitary extrudate as a polymeric thin wall member with or without a unitary capstock layer and with or without streaker material in the unitary extrudate.
17. The method of
vacuum embossing an exterior of the thin wall member to form a low gloss textured pattern having a gloss level of less than about 50 on a 60° glossmeter;
calibrating a profile of the thin wall member;
cooling said profile after calibrating the profile; and
cutting said thin wall member to a length of about 2 feet to about 20 feet.
18. The method of
extruding the unitary extrudate as a coextruded substrate and a weather resistant capstock layer, wherein the capstock layer retains its thickness beneath the low gloss textured pattern to maximize a weather resistant thickness of the capstock layer.
19. Apparatus for making a hollow polymeric building product, comprising:
extruder means for extruding a unitary polymeric extrudate with or without a capstock layer;
a vacuum embosser for embossing surface texture in exterior surfaces of the extrudate while supporting interior surfaces of the extrudate; and
a forming die for forming the extrudate into the polymeric building product.
20. The apparatus of
mandrels supporting the interior surfaces of the extrudate while embossing the surface texture, or a mold belt supporting the interior surfaces of the extrudate while embossing the surface texture, or a mold chamber supporting the interior surfaces of the extrudate while embossing the surface texture.
This application claims the benefit of both U.S. Provisional Application No. 60/807,081, filed Jul. 12, 2006 and U.S. Provisional Application No. 60/807,082, filed Jul. 12, 2006.
This application is related to U.S. application Ser. No. 10/281,795, filed Oct. 28, 2002, of Byeong Jo and John Peavey, entitled “Plastic Decking System Reinforced with Fiberglass Reinforced Thermoplastic Composites” (D0932-00200); U.S. application Ser. No. 09/190,038, filed Nov. 12, 1998, of Thomas Gilbert, David Jacobson, and Rick Lappin, entitled “Shaped Polymeric Articles” (D0932-00088); U.S. application Ser. No. 09/735,681, filed Dec. 13, 2000, of Thomas Gilbert, Kenneth Bosler and Steven Booz, entitled “Staggered Look Shake Siding”, now U.S. Pat. No. 6,737,008, issued May 18, 2004 (D0932-00230); and U.S. application Ser. No. 11/247,620, filed Oct. 11, 2005, of Jong P. Jeng, entitled “Building Material Having a Fluorocarbon Based Capstock layer and Process of Manufacturing Same with Less Dimensional Distortion” (D0932-00593); the entirety of which are incorporated herein by reference. The Examiner's attention is drawn to the prior art cited, or otherwise of record, in these related applications.
This invention relates to substantially hollow, closed, thin wall profile building materials having a low gloss textured pattern disposed continuously along one or more surfaces thereof.
There have been a number of polymeric products made to look like natural wood for decking and siding applications. Such products are formed by extrusion and embossing processes, or by injection molding in a pattern mold to simulate a wood grain or pattern. Such products comprise a painted or otherwise “decorated” or printed pattern to simulate wood or other materials, such as marble or natural stone, for example. Such teachings are provided in Franco et al., US2005/0053767; Giacchino, US 2005/0127345; Barre et al., U.S. Pat. No. 5,331,602; Anstadt et al., U.S. Pat. No. 4,141,944; Bosler, U.S. Pat. Nos. 5,906,840; 5,314,325, 6,823,794 and 6,641,384; Cameron et al., U.S. Pat. No. 5,053,176; Dorchester et al., U.S. Pat. Nos. 5,866,054 and 5,869,176; Saloom, U.S. Pat. No. 5,387,381; and Soda et al., U.S. Pat. No. 3,936,518, which are hereby incorporated by reference. Most of these disclosures, other than the Bosler patents, relate to the use of embossing rolls located immediately downstream of the extrusion die. The embossing operation is designed to emboss the surface configuration, or provide ornamentation onto the capstock layer side of a plastic sheet. The embossing rolls apply tension to the sheet of plastic to draw the sheet of plastic down to a particular dimension. Following embossing, the embossed sheet is typically preformed in a die into a rough version of a siding profile. See, for example, Dorchester et al. U.S. Pat. No. 5,869,176, at col. 6, lines 11-26. While siding can be embossed readily with good effect, the high pressure of embossing rolls is ill suited for hollow profiles, such as fence boards and hollow decking planks, which would likely collapse under such pressure.
Multiple hollow fence board products made of thermoplastic materials are available in the market. Present hollow, semi-hollow, thin walled fence boards made of polymer based materials (neat, composite, or with fillers) made in extrusion processes have a surface which is smooth or enhanced by longitudinal, machine- or extrusion-direction texture, lines, ribs, or depressions. Such products do not have the look of natural wood, such as softer areas indicative of environmental wear, or harder areas which are generally more resistant to environmental wear. These hard and soft areas form peaks and valleys on the natural wood board surface following natural wood patterns which do not always line up with the machine- or extrusion-direction of synthetically made materials. Furthermore, hollow, thin wall fence board products currently available in the market exhibit a high surface gloss which reveals the true character of this material, and often make them undesirable on aesthetic grounds.
Continuous and semi-continuous processes for creating patterns on extruded plastic sheets have been used in the building components industry for a number of years. Some prior systems have disclosed rigid linked patterns for forming shaped impressions in an extruded sheet material. Unfortunately, such rigid shaped patterns tend to form unsightly horizontal seams in the material. Other systems have used pattern forms on rotating cylindrical drums. Although these processes are continuous, and do not produce horizontal seams, they often require expensive additional equipment and instrumentation to align the arcuate surface of the pattern with the relatively flat surface of the product, and to avoid, or correct, unwanted bowing of the product.
Because of the limitations on prior continuous processes, some manufacturers have opted for injection or blow molding building products one at a time. While such techniques can provide the desired detail in texture and surface finish, they are generally limited to product sizes of about 4-5 feet in length and provide product thicknesses which are practically limited to greater than about 0.080 inches. This is generally because of the difficulty associated with flowing hot viscous polymer through thin cross-sectional profiles in steel molds. Additionally, because of the known size limitations, the randomness of individual features on the surface of a molded product is limited. This results in only a relatively small number of pattern elements, such as shingles, being molded into the relatively small surface area. When several of these products are aligned side by side on a wall or roof of a building, for example, it is sometimes obvious to see the pattern repeated over and over again. Accordingly, there remains a need for improved vacuum embossing techniques for use in connection with extruded hollow thin wall profile products.
An exterior building product comprises, a polymeric unitary hollow member having a hollow interior portion and an exterior portion, and said polymeric unitary hollow member being closed along all exterior sides. According to an embodiment of the invention, the exterior sides are unitary with the hollow member, and are either seamless or pivot along a hinge and latch together.
A building product comprises a continuous length pattern of surface topography features embossed in exterior sides of a hollow member formed as a unitary extrudate. The invention further includes a process and apparatus for making the building product, wherein the exterior sides are supported to resist collapse thereof while heat and forces are applied during embossing, and the sides form a hollow unitary extrudate with ribs extending between the sides. According to an embodiment of the invention the unitary extrudate comprises a hollow extrudate wherein the interior of the hollow extrudate is supported by mandrels after extrusion and during embossing to resist collapse thereof. According to another embodiment, the extrudate has unitary ribs and is folded to form a hollow configuration with the ribs interlocked. Further embodiments of the invention pertain to a method of making a hollow building product having embossed exterior surface texture elements or features formed by embossing a continuous length of a hollow unitary extrudate while supporting the extrudate to resist collapse thereof while heat and forces are applied during embossing.
According to another embodiment of the invention, a continuous length pattern of surface topography features are embossed in exterior sides of a unitary extrudate, wherein the exterior sides having the surface topography features embossed therein are pivotable about a unitary hinge such that the exterior sides close and form a hollow unitary product. Further embodiments of the invention pertain to a unitary hollow product having extruded unitary interior reinforcing ribs. Further embodiments of the invention pertain to a continuous length pattern of embossed surface texture elements embossed lengthwise in a unitary product, wherein the surface texture elements or features are irregular in recessed depth, raised height and area pattern, to appear as randomly shaped surface texture elements or features occurring in respective natural materials. Further embodiments of the invention pertain to a hollow unitary product having unitary internal reinforcing ribs and unitary exterior surface topography features formed by embossing opposite sides of the hollow unitary product. In an embodiment of the present invention, an exterior building material is provided which includes a substantially hollow, closed, thin wall profile comprising a polymeric composition, the profile including an interior-facing surface portion and an exterior-facing surface portion. Upon the exterior-facing surface portion of the profile is presented a low gloss textured pattern disposed continuously along the exterior-facing surface portion. The low gloss textured pattern has a gloss level of less than about 50 on a 60° glossmeter, and has at least one cross-machine direction textured pattern element.
A further embodiment of the present invention provides an apparatus and a method of making an exterior building material comprising extruding a first polymeric composition including an additive and a colorant through a die to form a polymeric profile having a substantially closed, hollow shaped form; supporting an internal surface of said hollow shaped form with a mandrel; vacuum embossing the polymeric profile on a flexible rotating belt to form a textured pattern, said textured pattern disposed on an exterior surface of said polymeric profile; whereby said mandrel supports said internal surface of the hollow shaped form against a collapsing force while also assisting in providing a better vacuum seal. Following the vacuum embossing step, the embossed profile is calibrated, cooled and cut.
A further embodiment of the present invention employs a hollow extrudate supported internally by one or more mandrels, each preferably a floating mandrel, such as a PTFE or fluorocarbon resin coated steel mandrel or a unitary PTFE or fluorocarbon mandrel that is solid or hollow, and which is disposed inside the extruded soft profile of the extrudate. The preferred floating mandrel is a rigid, low friction, internal support, which prevents the extruded shape from collapsing and prevents the rubber or silicone belt from sagging and breaking its vacuum seal with its underlying perforated metal belt. The floating mandrel is preferably disposed between the extruder and the end of the embossing step, more preferably, from the beginning of the embossing step to about the location of the vacuum chamber or vacuum boxes. The vacuum boxes can thereafter assist in keeping the outer wall of the extruder profile and the silicone belt in close proximity to the perforated metal belt by vacuum pressure.
In a further embodiment of the present invention, a continuous method of making an exterior building material is provided. The method includes the steps of extruding a first polymeric composition including adding a colorant through a die to form a polymeric sheet; vacuum embossing the polymeric sheet on a flexible, rotating belt to form a low gloss texture pattern of about 2-20 feet in length, the textured pattern disposed on the polymeric sheet and having a gloss level of less than about 50, and more preferably 30 or less, on a 60° glossmeter. The textured pattern includes at least one textured element disposed in a cross-machine direction. The process further includes forming the embossed polymeric sheet into a closed, hollow shaped article; calibrating the shaped article; cooling the calibrated and shaped polymeric article; and cutting said cooled and calibrated shaped polymeric article.
In still a further embodiment of the present invention, an exterior building material comprising first and second substantially hollow polymeric shell portions are joined together by a hinge and fastened together by fastening means to form a substantially hollow thin wall polymeric article. The polymeric article has a low gloss simulated wood grain disposed on an exterior-facing surface portion thereof.
In yet another embodiment of the present invention, an extruded product comprising an elongated member having a first side comprising a capstock layer; and a second side comprising one or more male fastening members disposed along one lateral side of said second side, and one or more female fastening members disposed along an opposite lateral side of said second side; said polymeric member being foldable along a central, longitudinal axis so as to connect corresponding ones of said male and female fastening members together to form a hollow, closed, thin wall building material having generally a length of about 2-20 feet. These male-female connections are made while the polymeric material is still hot, so as to allow the male and female members to melt-bond together, or these connections are joined after cooling to form a mechanical joint or supporting structure.
In a further embodiment of the invention, a continuous method of making an exterior building material is provided in which a first polymeric composition is extruded through a die to form a polymeric profile having a form selected from the group consisting of: shells, a substantially closed, hollow shape, and a sheet. The polymeric profile is then vacuum embossed on a flexible rotating belt to form a low gloss textured pattern of about 2-20 feet in length, the textured pattern disposed on said polymeric sheet having a gloss level of less than about 50 on a 60° glossmeter, and having at least one textured element disposed in a cross-machine direction. The embossed, polymeric profile is then formed, calibrated and cooled prior to cutting the formed, cooled and calibrated profile.
The preferred extruded products of this invention have a hollow, thin wall having a thickness of about 0.005-0.25 inches (0.127-6.35 mm), preferably, less than about 0.100 inches, and more preferably, about 0.055-0.080 inches.
The accompanying drawings illustrate preferred embodiments of the invention as well as other information pertinent to the disclosure in which:
The present invention is designed to make exterior building materials, such as hollow or semi-hollow (hereinafter just “hollow”) fence boards, decking, window frames, door skins and ceiling tiles or panels and some siding and roofing products which have improved natural surfaces, such as surfaces resembling natural wood, including texture, grain pattern, colorant pattern and low gloss. The proposed combination of extrusion processing with embossing, such as, by continuous vacuum embossing processes, is capable of enhancing product appearance by applying a low gloss pattern of about 2-20 feet in length in any direction, including a cross-extrusion or cross-machine direction, to a thin wall product surface to emulate a natural texture. Furthermore, combining thermoplastic materials with colorants and streaker pigments, for example, or a combination of extrusion processes with inline decorating processes, such as printing, adds grain patterns as a final requisite of a natural wood appearance. Finally, by producing building materials having a hollow profile, posts and rails and fence boards and decking planks are made from polymeric materials inexpensively, but yet have surface texture, grain pattern and low gloss resembling natural wood.
The present invention relates to methods of producing exterior building materials having substantially hollow configurations, preferably with shaped profiles and methods of manufacturing the same. As used herein, the term “embossing” means a mechanical or chemical process that puts texture into an otherwise smooth finish. The term “gloss” is a measurement of the reflection of light off a finished product at a given angle of incidence and reflection. Sometimes measured using a glossmeter, it is expressed as a numerical reading. The higher the gloss level, the shinier the surface. The term “matte” refers to low gloss or an absence of gloss. Also as used herein, the term “grain” means the direction, size, arrangement and appearance of fibers or patterns in a wood-like material, or the simulation thereof. As used herein, the terms “heat deflection temperature” is the temperature at which a polymeric material deflects 0.010 in. under a load of 66 or 164 psi, as defined in ASTM test D 648. Also as used herein, the term “polymeric material” shall mean polymeric compositions which includes but is not limited to, compositions having, additives, such as ultra-violet light stabilizers, fillers, plasticizers, tints, and other additives, such as glass or wood fiber. The term “molded” means any number of processes, or combinations thereof, for forming an impression in a polymeric material, including compression molding, transfer molding, injection molding, blow molding, autoclave molding, contact molding, pressure bag molding, vacuum bag molding, deep draw molding, lay-up molding and spray molding, etc.
The preferred method of this invention is best understood by reference to the
The first and second rollers 520, 530 of each flexible rotating mold belt 516 and 515 of the embosser 30 are spaced apart from one another in a generally horizontal direction such that the rotating belt 516, 515 extends between them, and forms a substantially flat forming surface. The mold belt 516 and 515 is preferably made of a resilient flexible material such as rubber, or rubber-like material, such as silicone or synthetic rubber.
Each mold belt 515 and 516 and corresponding drive belt 513, 514 are frictionally or mechanically engaged so that, by driving the drive belt 513, 514 with drive axle and drive roller 520, the corresponding mold belt 515 and 516 moves as well. The mold impression of the mold belt 516 and 515 substantially retains its shape as it spins, or stretches slightly, so there is no need for multiple sections and seams. The continuous mold impression preferably is a continuous length pattern of surface texture elements or features on a corresponding continuous mold belt 516 and 515. The continuous mold impression is transferred by being impressed by continuous vacuum embossing into the opposite sides of the product 60 in
The present invention further relates to creating patterns such as variegated colors or wood grains on hollow-profile building materials, for example, decking, fencing posts, rails, boards, railing, siding and window framing applications, to name a few. This invention may employ sprayed, painted, coated or printed capstock layers and top coat layers having a total thickness of preferably less than 4 mils, and more preferably 1 mil or less, which have the ability to perform well long term, and have ample weathering performance, mildew resistance, and dirt repellency, while simultaneously providing good adherence to thermoplastic substrates, such as those manufactured with PVC, polyethylene, polystyrene, polypropylene, either in virgin or recycled form.
With reference to the Figures, and particularly
After blending, the compound is conveyed to the extruder 20 where it is carefully metered so a consistent amount of material enters the hopper 10. The extrusion operation is a process in which thermoplastic resin is pushed through a heated barrel and die by one or more large, precisely tooled screws. As they turn, the screws knead and thoroughly mix the thermoplastic compound and additives such as UV stabilizers, plasticizers, blowing agents, copolymers, and/or other extrudable thermosetting resins. Both the screws and the barrel of the extruder are preferably heated which melts the resin and makes it easier to mix and push. The heat (300 to 400° F. for PVC), also accelerates the physical reaction (fusion) between resin and the micro-ingredients in the compound.
Most building products, such as siding, are extruded with twin-screw extruders. Twin-screw extrusion is preferable to single-screw extrusion because it heats and distributes material more evenly, resulting in a product with better physical properties. As the resin compound is forced ahead of the rotating screws, the very tight tolerances in the double barrel promote complete fusion of the ingredients. Color concentrate is added at the extruder, which helps to produce a rich, durable, all the way through color, in each exterior building product.
Co-extrusion, is used to join two flows of molten resin compound from two extruders 20 and 70 in a single die to produce an extrudate of a single polymeric sheet comprising two layers of materials, such as a substrate and a “capstock layer.” As used herein, the term “capstock layer” refers to a thin protective layer added to some exterior building products to improve weatherability and color retention. The capstock layer comprises either a single layer of polymeric material, or comprises a multilayer having two or more polymeric layers, each of which is extruded one over the other, either by coextrusion in a single extruder, or by separate extrusion in a number of successive extruders. The one or more layers comprising the capstock layer are unfoamed and are preferably nonporous and selected to provide a visually aesthetic, finished surface and which comprise polymer compatible additives imparting chemical and mechanical properties, for example, water and moisture resistance, flame resistance, ultraviolet resistance, surface texture or finish, colorfastness, toughness, solar reflectance, wear resistance, impact resistance and stain resistance. In an embodiment of the invention, one or more layers of a multilayer capstock layer comprises a matrix of translucent resin or transparent polycarbonate for example, and an alternative embodiment of an accent color streakers of polymeric colorant in opaque and transparent or translucent layers comprising the capstock layer. Typically, the capstock layer material comprises acrylic-containing resin, such as AES, ASA, or alternatively, polyethylene or polypropylene. Capstock layer co-extrusion requires a processing window due to the difference in coefficient of linear thermal expansion rates between the capstock layer and base or substrate. Missing this window often leads to unacceptable dimensional distortion or bowing of the panel, lineal, lintel or framing member, fence or board, for example.
Some building products 60, 60′, 160, 160′, 260, 260′ and 360 are treated with a post-forming step or steps. Equipment, such as vacuum sizers of the calibration die 40 and post-formers, provide greater consistency in post-formed thickness and profile. Post-formed locking devices in siding, for example, disclosed by U.S. Pat. Nos. 6,319,456 and 6,737,008, comprise tighter tolerances and more intricate interlocking structures, which result in higher wind load ratings. Post-forming operations further include the calibration dies 40 including but not limited to, pre-sizers and vacuum sizers and shaping dies (collectively, 40) prior to the cooling tank 50 to create distinctive profiles and a wide range of sizes for products 60, 60′, 160, 160′, 260, 260′ and 360. In a vacuum sizer as the calibration die 40, the product is given a crisp finish profile. In
The cooling tank 50 is located after any post-forming operation. Once the hot sheet, including an optional, i.e. alternative embodiment of, a painted and/or printed layer over the polymeric substrate, is introduced into the cooling tank 50, the product temperature quickly drops below its “heat deflection temperature” and the final shape sets. An embodiment of the invention comprises a gravure roll coater or other form of a printer 311,
A coating step comprises printing by a gravure roll coater (“print roll”) comprising an exemplary embodiment of the printer 311, 312 or 313,
After passing through the cooling tank 50, the substrate and alternative embodiments of a painted or printed layers and/or alternative embodiments of a capstock layer are optionally punched with openings, not shown, at precise intervals for insertion of metal supporting rods, nails or fasteners and the like. Finally, the product 60 is cut to length at cut off, inspected and packaged.
The embodiments of the invention comprise one or more spraying, painting, and/or printing steps (“coating step”) disclosed in
The inks, pigments, coatings or paints create variegated wood grains and colors applied by direct printing or coating, for example, is provided without collapsing distortion or bending of thin panels, long decking planks, or intricate window lineal, lintel or framing member, fences. Preferably, the total coating thickness will be less than 4 mils, and preferably, 1 mil or less, compared to existing co-extruded ASA capstock layers of about 4-6 mils, used in PVC siding, for example.
While various coatings are employed in connection with variegated surfaces of this invention, those including PVC, polyethylene, polypropylene, ASA and other acrylic-based compositions and fluorocarbon resins, such as, polytetrafluorethylene, PTFE, PFA, ETFE, ECTFE, FEP, polyvinylidene fluoride, PVDF, PPS, EFEP, TEFLON®, and other thermoplastic or thermosetting resins, are desirable. These compositions are applied to thermoplastic or thermosetting sheets or construction materials by such techniques as thermal spraying, paint spraying, fusion coatings, inkjet printing, and gravure roll printing, for example.
One method for making the capstock layer and the first, second, and subsequent top coat layers of the variegated building products of this invention, employs a water base emulsion ink or paint containing a copolymer of PVDF and Hexa Fluoro PVDF that is polymerized in the presence of an acrylic component. The preferred coating is sold under the trademark Kynar® and is provided by Arkema.
The hollow building product of this invention also relates to an article that has a variegated effect appearance. The article comprises a mixture of a substantially non-opaque (i.e., neither transparent nor translucent) polymer matrix, and color particles having different melt flow properties from the polymer matrix. The initially discrete color particles are suspended in the non-opaque matrix, and streak out during processing, acting as accent color pellets or masses. By “streak out” is meant that the color particles extend and form variegated lines and shades of color for example the colorant streaker pattern of grain color or grain indicia 137. The transparency or translucency of the non-opaque matrix adds a depth or dimension to the variegated appearance. For exterior applications, at least the outermost layer, which would be exposed to the environment, is protected by appropriate antioxidants, thermal stabilizers, photostabilizers, etc.
The melt index (MI) of a polymer resin is a measurement of processability under low shear rate conditions. The MI is determined by ASTM D-1238 (for example, Condition E for PVC) (190° C./2.16 kg). For instance, the MI of the polyolefins is generally between about 0.2 dg/min, and about 100 dg/min, preferably, between about 1 dg/min and about 10 dg/min, and most preferably, between about 2 dg/min and about 8 dg/min. The MI of the polymer resins are measured using ASTM D-1238.
When thermoplastic materials are heated, the thermoplastic begins to soften, its physical properties changing in various ways. The temperature at which a measurable softening of the thermoplastic occurs when heated is, preferably, measured by the “vicat” method, and is referred to as the “vicat softening point temperature”. Analogous or related temperatures are measured by other methods, resulting in other scales of temperature versus physical property, such as the heat deflection temperature, or the melt flow index. The vicat method and scale, preferred by the present inventors, is specified by ASTM-D-1525, from which the vicat softening point temperature referenced herein was obtained. The vicat softening point temperature indicates the softening temperature at which the resin begins to melt in response to increased temperature. The melt flow index is a measure of the viscosity of a resin when it has fully melted.
The transparent matrix material includes either a plurality of types of color particles and/or accent color pellets. The variations in color particle type include different colors of pellets, different sizes of pellets, different melt flow behavior of pellets, or pellets having different relative viscosities compared to the matrix polymer. The different colors will result in different sizes or shapes of streaks. The different viscosities will result in different lengths of streaks. The different kinds of pellets contribute to the complexity of the variegation obtainable with this invention, and to the aesthetics of simulation of a wood grain or a mineralogical veining effect for the finished article. Methods whereby the formation of the article are accomplished include for example, extrusion, molding, and injection molding.
Furthermore, an article made by the processes of the present invention alternatively comprises a plurality of variegation layers wherein each of the layers includes a transparent or semi-transparent matrix, and one or more kinds of accent color particles. The layers are formed, for example, by extrusion of individual layers followed by lamination or bonding to construct a multilayer article. Alternatively, the various layers are coextruded through, for example, a plural manifold die system to form the multilayer article in fewer steps. The articles of the present invention are provided with a transparent or translucent protective overlayer or capstock layer, by means of such as lamination, coextrusion or coating applications. The coating step includes but is not limited to, hot painting, thermal spraying, paint spraying, fusion coating, inkjet printing and gravure roll coating, for example. The article also includes a colored base layer, which color is at least partially visible through the non-opaque, transparent or translucent, matrix of the streaker-containing layer.
Different types of color particles include, for example, color, size and melt rheology. Different sizes will result in different widths or shapes of color streaks. Different melt rheology or viscosity during processing will yield different behaviors in streak flow. For example, lower viscosity streaker particles will stretch out more on processing. Larger particles produce wider streaks of variegation. Color particles with greater miscibility/compatibility with the matrix polymer will produce streaks having more diffuse boundaries.
The materials of this invention comprises various transparent or translucent matrices which are the same or different chemical families. The layers are selected for controlling other functionality required in the end product. The rheology of each transparent or translucent matrix are balanced for the given color particles contained therein. Each layer provides other functionality, such as, for example, stabilization and UV protection in the outer layers, chemical resistance, or resistance to dirt pickup.
An alternative embodiment of a transparent matrix comprises a transparent colorant. This transparent colorant could be a dye or a small particle pigment. The use of transparent color of a layer containing a transparent colorant provides a degree of freedom in imparting a desirable depth in appearance to the article. Also, a single color particle type is used in each transparent matrix, or a given layer comprises more than one kind of color particle.
The colored base or substrate layer comprises any material desired in making the article of the invention. For example, it comprises a filled base polymer of less weatherable materials that are protected by the upper layers which also contribute to a desirable aesthetic. An embodiment of the base or substrate itself comprises a plurality of layers. In one instance, it comprises a colored surface layer adjacent to the variegation layers, with a layer containing fillers beneath. The base or substrate layers contribute substantially to the bulk mechanical properties of the article, while the variegation layers provide a desirable appearance.
In a first embodiment of the present invention, a continuous length hollow extrudate 60 or 60′,
Thin wall hollow profiles remain hot and soft during vacuum embossing. The upper silicone belt 516 of the vacuum embosser 30 is relatively heavy and tends to sag into the soft hollow profile, which is too thin to support the weight of the sagging silicone belt 516. This causes the top wall of the profile to collapse. This, in turn, creates a gap “a” between the silicone belt 516 and the perforated belt 514′ releasing the vacuum. The result is poor product quality.
As shown in
As shown in
The surface texture elements or features 135, 235, 335 are irregular in recessed depth, raised height and area pattern having a dimension that varies in the cross-machine direction laterally of the continuous length, to appear as randomly shaped surface texture elements or features occurring in respective natural materials compared to a process of extrusion that is limited to producing straight length dimensions and constant cross sectional dimensions such as a straight groove of constant depth or a raised straight rib of constant height. The textured surfaces have a gloss level of less than about 50 on a 60° glossmeter, and the texture pattern has at least one texture pattern element with a dimension that varies in a cross-machine direction relative to the machine direction of the extrudate formed by extrusion. Following embossing, the embossed sides and thin wall profile of the embossed extrudate are subject to a calibration die 40 including but not limited to, a vacuum sizer or shaping die (collectively 40), or a combination thereof. Following sizing or other calibration, the embossed extrudate is then cooled in a cooling tank 50, and emerges as a finished product 60, 60′, 160, 160′, 260, 260′ and 360, respectively. The vacuum embosser 30 provides the hollow profile with a low gloss, textured surface 135, 235 and 335, respectively, which comprises a pattern of surface texture features, wherein the surface texture elements or features are irregular in recessed depth, raised height and area pattern, to appear as randomly shaped surface texture elements or features occurring in respective natural materials, for example, a wood grain pattern,
The capstock 138 or 238 provides a weather durable layer covering and protecting the core or base material of the vacuum molded product. An advantage results from vacuum molding the surface topography recesses 135 in the weather durable capstock 138 or 238 compared to etching, stamping or abrading to remove capstock material. The vacuum molded capstock 138 or 238 retains its desired thickness under each surface topography recess 135 formed by vacuum molding to maximize the thickness of the weather durable protection. The less viscous core or base material flows to become thinner. Thereby, the vacuum formed capstock 138 or 238 has a maximized thickness of weather durable protection, compared to etching, stamping or abrading to remove capstock material, which reduces the thickness and the useful life of the weather durable protection.
The extruded embossed profile of the folded sheet,
The finished product 160, 160′ has a closed hollow profile, shown in
The preferred capstock layer, 138 or 238 or, alternatively, the exterior second major surface of the product 60, 160 or 260 in the absence of the capstock layer 138 or 238, includes streaks of a grain color 137 or 237 and embossed texture 135 or 235, as substantially shown in
With reference to
The die of the extruder 20 is capable of converging the base thermoplastic for the substrate with a second thermoplastic material from the extruder 70 creating an outer layer or capstock layer 238 on the top of the first plastic material. This die of the extruder 20 has a low friction, floating mandrel or mandrels 31 so as to maintain a thin wall “hollow” product 260 or 260′ with unitary internal ribs 162 similar to that of the product 60,
As shown in
As shown in
A fence board trial was conducted using new embossing belts on a vacuum forming machine with belt cooling fans. The following compositions were employed:
substrate: PVC with additives such as stabilizers, lubricants, impact modifiers, calcium carbonate and titanium dioxide for UV protection.
capstock layer: ASA with additives such as stabilizers, lubricants, impact modifiers, calcium carbonate and up to 10 parts of titanium dioxide for UV protection.
This product was made in a co-extrusion process in which substrate material PVC was extruded through a die by a first extruder, and capstock layer ASA material was extruded into the same die from another direction by a second extruder using the following settings:
Both the substrate and capstock layer materials merged in the extrusion die and exited the die orifice (exit) as a single hollow shape thin wall product made of two materials with each of them having different compositions.
The following color settings, sequences and measurements were made:
The trial sequence was:
a. started with white pellets;
b. added Brown Streaker pellets 54120-A4 from Americhem (still using PVC base);
c. changed to ASA/Clay pellets; and
d. added Timber Streaker pellets 9062-A3 from Americhem (Centrex based color concentrate).
The melt temperature for PVC was 390° F.; for ASA it was 405° F. The profile strung up very easily once again with little or no difficulty attaining vacuum.
Auxiliary fans were used on both top and bottom belts for cooling. The belt temperature was approximately 205-210° F. A belt temperature below 200° F. will dramatically prolong the belt life. All dimensions were achieved with puller and belt speed adjustments. Currently, there is only one color feeder per extruder. Streaked color will typically require two feeders.
The hollow shape thin wall profile exited the die in a soft state with a high temperature and low rigidity. It then entered a system made of one, two, or more flexible rotating belts being strategically placed on the side(s) of the product where surface texture is required. In order for the texture transfer process to take place, the product had to be in a soft state. Vacuum was employed to draw the product toward the textured surface of the belt. For the vacuum force to take action, the vacuum chamber must be sealed. Due to its soft state, the extruded profile by itself can not support its own weight and the weight of sagging flexible belt. As such, the vacuum chamber is not sealed and texture transfer does not take place.
A floating mandrel(s) made of PTFE (or any other rigid material with a low friction surface) was employed to increase the rigidity of the system and close the seals between vacuum chamber, rotating flexible belts, and constantly moving forward soft extruded product, This floating mandrel(s) was attached by flexible means to the stationary metal mandrel(s) of the extrusion die. During the extrusion process, the floating mandrel located itself in such a position in respect to the vacuum chamber, that it sealed the extruded hollow shape thin wall product floating over the mandrel(s), which helped to seal in the entire belt system. This enabled the applied vacuum to pull the extruded product against the textured belt surface so that texture transfer took place.
After exiting the rotating flexible belts, the extruded product with a desired texture entered a vacuum calibration die with a cooling tank following the calibration process. In the final step of this process, the extruded product was cut to a desired length.
The final product had improved texture, definition and lower uniform gloss, when compared to a fence board of the same composition, but without texture.
These were deemed to be very positive results. All of the colors and material combinations produced very good looking samples. The Brown Streaker was not used in conjunction with any base colors, so it was just streaks on a light background color. Timber Streaker didn't provide much of a streaking effect because it melted so quickly in the ASA. Mandrels are attached to the die by wire and stainless steel fasteners, such as, eyebolt, 304 SS, 3/16″-24, 2″ shank, 1″ thread. McMaster Carr p/n 9489T81.
The resulting board had a textured pattern with a gloss reading of 27 on a 60° glossmeter, whereas a smooth PVC board made of the same materials had a gloss reading of 33 on a 60° glossmeter. The gloss was measured with Glossmeter Model 500-60°, manufactured by Erichsen Testing Equipment.
A white fence board was produced by co-extrusion using a parallel screw extruder 125 mm. screw diameter to extrude PVC substrate, and a conical twin screw extruder 62 mm. screw diameter to extrude PVC capstock.
substrate: PVC pellets with additives such as stabilizers, lubricants, impact modifiers, calcium carbonate and titanium dioxide for UV protection
capstock layer: PVC pellets with additives such as stabilizers, lubricants, impact modifiers, calcium carbonate and up to 10 parts of titanium dioxide for UV protection. PVC capstock is used for light color products. (In our situation, PVC capstock is used to produce white boards or light color boards).
The melted PVC substrate and melted PVC capstock merged in the extrusion die and exited the die orifice (exit) as a single hollow shape thin wall product made of two PVC based materials with each of them having different compositions. The melt temperature for PVC was 390 deg F. The hollow shape thin wall product after exiting the die has smooth (flat) external surface.
The product was made with extruders settings as in the below table:
After exiting die the hot and flexible hollow shape thin wall product with smooth (flat) outside surface was pulled over floating low friction rigid mandrels attached by flexible means to pins in the die and suspended between silicone belts of the equipment having a textured surface.
The settings of the vacuum belt velocity were set to equal the exiting extrusion velocity of the thin wall hollow shaped product of 12 feet per minute, as in the below table:
After exiting the rotating flexible belts, the extruded product with a desired texture entered a vacuum calibration die with a cooling tank following the calibration process. The set up of the calibration die and ballast vacuum tank was as in the below table:
In the final step of this process, the extruded product was cut to a desired length.
A fence board was produced by co-extrusion similarly as in Example B, except for Example C comprising ASA capstock material substituted for the PVC capstock material of Example B.
capstock layer: ASA pellets (with additives such as stabilizers, lubricants, impact modifiers and titanium dioxide for UV protection. ASA capstock is used for dark color products, for example, dark brown and clay color boards.
Color concentrate pellets were added to both materials at the same point as the material using separate single-screw color feeders with settings as in the below table:
PVC substrate with colorant and ASA capstock with colorant merged in the extrusion die and exited the die orifice (exit) as a single hollow shape thin wall product made of two materials: PVC substrate and ASA capstock. The melt temperature for PVC was 390 deg F. and for the ASA capstock was 405 deg F. The hollow shape thin wall product after exiting the die has smooth (flat) outside surface. The product was produced with extruders settings as in the below table:
After exiting die the hot and flexible hollow shape thin wall product with smooth (flat) outside surface was pulled over floating low friction mandrels attached by flexible means to pins in the die and suspended between silicone belts of the equipment changed from flat (smooth) external surface for impression in the product to a textured surface.
According to Example D, a fence board was produced similarly as Example C and with streaker pellets added to the capstock layer of Example D.
substrate: PVC with additives such as stabilizers, lubricants, impact modifiers, calcium carbonate and titanium dioxide for UV protection
Color concentrate pellets were added to both materials at the same point as the material using separate single-screw color feeders with settings as in the below table:
From PVC substrate with colorant and ASA capstock with colorant and streaker merged in the extrusion die and exited the die orifice (exit) as a single hollow shape of thin walls made of two materials: PVC substrate with colorant, and ASA capstock with colorant and streaker. The melt temperature for PVC was 390 deg F. and for the ASA capstock was 405 deg F. The hollow shape thin wall product after exiting the die has smooth (flat) outside surface.
The product was produced with the same, extruder(s) settings, belt settings and vacuum calibration die settings as for Example C.
The patents and applications referred to are hereby incorporated by reference herein.
From the foregoing description, an invention provides exterior building materials that include hollow, closed, thin wall profiles comprising a polymeric composition including additives and colorants. The exterior facing surface of the profile includes a low gloss, textured pattern disposed continuously along the exterior facing surface portion for about 2-20 feet. The present invention provides texture, pattern and low gloss similar to real wood products. The combination of extrusion processing with continuous vacuum embossing processes is capable of enhancing product appearance by applying a low gloss pattern in any direction, including the cross-extrusion direction, to thin wall product surfaces so as to emulate wood texture. In particular, hollow profile extrusion in combination with continuous vacuum embossing processes can be used to produce useful building materials emulating a natural texture. Furthermore, the combination of thermoplastic materials with colorants and/or a combination of extrusion processes with in-line decorating processes will add grain as a final parameter of natural wood fence boards, decking and other exterior building products.