Dimensionally stable building product with high recycle content

Abstract

A composite building product includes a polymer resin matrix, where the polymer resin matrix is composed of 25 to 100 wt.% recycled polymer and an inorganic filler dispersed throughout the polymer resin matrix, such that the composite building product has a post-anneal shrinkage of 0.01 to 0.9% and a coefficient of linear thermal expansion of 1.8x10-5 to 6.5x10-5 m / m / °C. The composite building product may be configured as trim, siding, decking board, fascia, or railing.

Description

DIMENSIONALLY STABLE BUILDING PRODUCT WITH HIGH RECYCLE CONTENT CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 777,938, filed March 26, 2025, the contents of which are incorporated herein by reference in their entirety.BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The accompanying drawings illustrate a number of exemplary embodiments and are a part of the specification. Together with the following description, these drawings demonstrate and explain various principles of the present disclosure.

[0003] FIG. 1 depicts an annealing apparatus for evaluating the impact of radiation exposure on composite building products according to some embodiments.

[0004] FIG. 2 shows the effect of annealing temperature on the deformation of composite siding boards having a moderate reground polymer content according to some embodiments.

[0005] FIG. 3 shows the effect of annealing temperature on the deformation of composite siding boards having a moderate reground polymer content according to some embodiments.

[0006] FIG. 4 shows the effect of annealing temperature on the deformation of composite siding boards having a high recycled polymer content according to some embodiments.

[0007] FIG. 5 shows the effect of annealing temperature on the deformation of composite siding boards having a high recycled polymer content according to some embodiments.

[0008] FIG. 6 shows the effect of annealing temperature on shrinkage for composite siding boards having a moderate reground polymer content according to some embodiments.

[0009] FIG. 7 shows the effect of annealing temperature on shrinkage for composite siding boards having a high recycled polymer content according to some embodiments.

[0010] FIG. 8 is a plot showing the impact of recycle content on permanent shrinkage according to some embodiments.

[0011] FIG. 9 is a graph showing the relationship between torque and time during an extrusion process using various blended resin compositions according to some embodiments.

[0012] FIG. 10 is a plot displaying dynamic thermal stability (DTS) time for various resin compositions according to some embodiments.

[0013] FIG. 11 shows the effects of resin composition on dynamic thermal stability (DTS) time and dynamic thermal stability (DTS) torque during extrusion processing according to some embodiments.

[0014] Throughout the drawings, identical reference characters and descriptions indicate similar, but not necessarily identical, elements. While the exemplary embodiments described herein are susceptible to various modifications and alternative forms, specific embodiments have been shown byway of example in the drawings and will be described in detail herein. However, the exemplary embodiments described herein are not intended to be limitedto the particular forms disclosed. Rather, the present disclosure covers all modifications, equivalents, and alternatives falling within this disclosure.SUMMARY

[0015] In some embodiments, a composite building product includes a polymer resin matrix, where the polymer resin matrix includes 25 to 100 wt.% recycled polymer, preferably recycled PVC, and a filler, preferably an inorganic filler, such as talc, dispersed throughout the polymer resin matrix, preferably, where the composite building product has a post-anneal shrinkage of 0.01 to 0.9% and a coefficient of linear thermal expansion of 1.8xl0-5to 6.5xl0-5m / m / °C. The filler may include an organic filler, an inorganic filler, or a combination of organic and inorganic fillers.

[0016] In some embodiments, the filler is capable of interaction with other components in the polymer formulation that forms the polymer resin matrix, whereby one or more of the recycled polymer components, the filler, and / or virgin formulation components operate synergistically to give, on extrusion and curing, a dimensionally stable composite building product that requires less annealing treatment than a comparable product without the recycled polymer content.

[0017] In some embodiments, the polymer resin matrix includes 50 to 75 wt.% of the recycled polymer. In some embodiments, the polymer resin matrix includes 75 to 95 wt.% of the recycled polymer. In some embodiments, the polymer resin matrix includes 95 to 100 wt.% of the recycled polymer.

[0018] The polymer resin matrix, in some embodiments, includes at least one thermoplastic polymer selected from polyvinyl chloride, polypropylene, and polyethylene. Insome embodiments, the polymer resin matrix may include 10 to 40 wt.% of the filler. The filler may include at least one compound selected from wood flour, calcium carbonate, talc, wollastonite, and mica, and may be dispersed homogeneously throughout the polymer resin matrix. In some embodiments, the filler has a mean particle size of 0.1 to 20 micrometers. In some embodiments, the polymer resin matrix further includes a thermal stabilizer and / or a processing aid. In some embodiments, the polymer resin matrix further includes a foaming agent.

[0019] In some embodiments, a method includes combining a polymer resin and a filler to form a polymer formulation and extruding the polymer formulation to form a composite building product. In some embodiments, the polymer resin includes 25 to 100 wt.% recycled polymer. In some embodiments, the composite building product exhibits a post-anneal shrinkage of 0.01 to 0.9% and a coefficient of linear thermal expansion of 1.8xl0-5to 6.5xl0-5m / m / °C.

[0020] In some embodiments, the polymer resin includes 50 to 75 wt.% of the recycled polymer. In some embodiments, the polymer resin includes 75 to 95 wt.% of the recycled polymer. In some embodiments, the polymer resin includes 95 to 100 wt.% of the recycled polymer.

[0021] In some embodiments, a total amount of the filler in the polymer formulation is greater than an amount of filler combined with the polymer resin. In some embodiments, the recycled polymer includes an inorganic filler. In some embodiments, the recycled polymer includes an organic filler. In some embodiments, the recycled polymer includes an inorganic filler and an organic filler. In some embodiments, the inorganic filler is talc. In some embodiments, talc is used as filler where the recycled polymer is recycled PVC polymer.

[0022] A composite building product may be formed from the polymer resin matrix. Example composite building products may have a form factor selected from trim, siding, decking board, fascia, and railing, although further configurations are contemplated. The composite building product is preferably an extruded composite building product formed by extrusion of the polymer resin matrix through a suitably shaped die.DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0023] The present disclosure relates generally to composite building materials and structural elements formed from composite building materials, and more particularly, in some embodiments, to composite polymer compositions having a high recycled polymer content that are configured to exhibit commercially relevant attributes, including strength, stiffness, and dimensional stability.

[0024] Composite polymer-based materials, including thermopolymers such as polyvinyl chloride (PVC), polypropylene (PP), and polyethylene (PE), together with selected additives, may be heated and extruded to form decking boards, siding boards, trim boards, and other structural elements. Such composite materials may be formed in a variety of shapes and sizes and may possess advantageous properties, including weatherability and aesthetic versatility.

[0025] Disclosed are formulations having a high content of recycled polymer, e.g., polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), and the like. Formulations including a high recycle content, in combination with fillers, may be used to decrease thermal shrinkage and increase temperature resistance in profile extrudates and / or composite building products, resulting in improved environmental footprint and enhanced heat tolerance before theonset of deformation, while obviating the use of greater amounts of filler and / or post-annealing, which may introduce unfavorably complex processing and higher costs. The filler may be a functional filler, i.e., additives that are incorporated into the formulation to improve specific properties, e.g., dimensional stability, flame retardance, mechanical enhancement, thermal stability, color, etc. In other embodiments, the filler may be an inert filler, i.e., added to bulk up a formulation. In some embodiments, the filler is preferably a functional filler, e.g., talc.

[0026] Composite building products may be formed using an extrusion process. In an extrusion process, raw materials including a plastic resin, filler(s), and various additional additives, such as foaming agents, thermal stabilizers, colorants, and the like, are mixed in specific proportions to provide targeted characteristics, such as mechanical and aesthetic properties. A blend of the raw materials is fed into an extrusion apparatus. The apparatus is configured to mix, heat, and melt the raw materials. The melt is then forced through a die, which shapes the molten materials into a desired form that is then cooled and hardened.

[0027] During an extrusion process, polymer chains may be subjected to significant stresses as they are heated and directed through the die to form structural elements having various shapes. The imposed stresses may align the polymer chains in a non-equilibrium state, however. Thereafter, a composite building product may be exposed to elevated temperatures such as those created by ambient heat or solar radiation causing the polymer chains to relax and return to a lower energy configuration. Relaxation and reorientation of polymer chains may lead to macroscopic shrinkage of the material and permanent deformation of the product.

[0028] Dimensional instability may be problematic in systems that rely on tight tolerances. Furthermore, excessive shrinkage can compromise the structural integrity of thematerial leading to potential durability issues over the lifetime of a product. In particular aspects, decreasing the extent of permanent shrinkage in PVC building products may lessen the appearance of unfavorable gaps between product runs in an assembled structure caused by dynamic environmental conditions such as thermal cycling.

[0029] A controlled reorientation and relaxation of polymer chains may be initiated by annealing. Annealing a polymer is a process where the material is heated to a temperature near or slightly greater than its glass transition temperature (Tg) to allow molecular chains to relax and attain a lower energy configuration. The glass transition temperature is the temperature at which the polymer transitions from a hard, brittle glassy state to a more flexible, compliant state and may be evaluated in accordance with ASTM D3418. During annealing, the polymer chains may acquire sufficient mobility to move into lower energy configurations, decreasing internal stresses.

[0030] Notwithstanding the foregoing, Applicant has demonstrated that postextrusion annealing of a composite building product may contribute to unwanted thermal stresses and concomitant deformation, in addition to added processing complexity and cost. The use of pre-annealed polymer materials, such as recycled polymer materials, may circumvent need for and thus challenges associated with post-extrusion annealing.

[0031] In view of the foregoing, it will be appreciated that recycled polymer materials may have undergone prior processing, including heating and cooling cycles, that may result in them having been annealed to some extent. This 'pre-annealing' effect can influence the material's properties, such as crystallinity, molecular orientation, and thermal stability. The preannealed properties of incoming recycled materials may beneficially influence the shrinkagereduction and heat resistance performance of resulting building products without necessitating a dedicated secondary (post-extrusion) annealing step.

[0032] While high filler content using minerals like calcium carbonate, talc, wollastonite, mica and clay may improve dimensional stability, they do not assist mitigating permanent product shrinkage. It had been expected that adding recycled polymer and / or filler material(s) to an oversaturated amount could disrupt or adversely affect processability of the PVC and create brittleness issues, such that the advantages of the present technology were unexpected.

[0033] In accordance with some embodiments, disclosed are composite building products formed using a high recycle content of constituent polymer, such as a high content of recycled PVC. As used herein, recycled PVC is material that has been collected, processed, and repurposed from waste products or discarded PVC items. Sources of PVC may include window lineal scrap, siding, pipe, fencing, and the like, as well as combinations thereof.

[0034] Recycled PVC may include rigid PVC and / or foamed PVC. Without wishing to be bound by theory, rigid PVC sources may be characterized by a higher average molecular weight and a higher degree of polymer chain alignment than foamed PVC sources.

[0035] PVC resins may be characterized by their K value. The K value of a polymer resin is a quantitative measure of the degree of polymerization of the material and hence its molecular weight and provides an indication of the polymer's intrinsic viscosity and its flowability during processing. For many PVC resins, the K value ranges from approximately 35 to approximately 80. In accordance with some embodiments, the recycle content in the composite building materials disclosed herein may have a K value ranging from 60 to 80, e.g., 60, 65, 70, 75,or 80, including ranges between any of the foregoing values. The K value may be measured in accordance with ASTM D1243.

[0036] Recycling helps reduce waste and decrease reliance on new raw materials. A waste product may be obtained from a waste stream including one or more of a regrind waste stream, a reprocessing waste stream, and a recycling waste stream.

[0037] Applicants have shown that when incorporated into structural elements such as decking, trim, or siding, high recycle content polymer formulations demonstrate lower permanent shrinkage and improved dimensional stability leading to lower material usage costs and less rigorous installation requirements relative to comparative, low reground content formulations.

[0038] As disclosed herein, a polymer formulation may include recycled polyvinyl chloride (PVC) although the independent use or inclusion of other recycled thermopolymers is contemplated. The polymer content of a composite polymer composition having a high recycle content may include from 25 wt.% to 100 wt.% recycled PVC, e.g., 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 wt.% recycled PVC, including ranges between any of the foregoing values. Recycled PVC material may include one or more of post-consumer or postindustrial content. A polymer formulation may additionally include one or more additives.

[0039] In some embodiments, a composite polymer composition may include particles of a filler such as an organic or inorganic (e.g., mineral) filler. Exemplary fillers include calcium carbonate, talc, wollastonite, mica, and various clay minerals. Further example fillers include wood flour, montmorillonite clay, fly ash, silica, glass beads, alumina trihydrate, calcium hydroxylapatite, and portland cement. Still further filler materials may include feldspar,bentonite, kaolin, barium sulfate, zinc oxide, magnesium hydroxide, aluminum oxide, glass fiber, carbon nanotubes, graphene, carbon fiber, PET fiber, and the like. One or more fillers may be incorporated into a composite polymer composition in an amount effective to promote dimensional stability without disrupting processability and embrittling a resulting building product.

[0040] In accordance with some embodiments, a composite polymer material includes a polymer resin component having, based on a total polymer resin content, 25 to 100 wt.% recycled thermoplastic polymer and a filler dispersed throughout the polymer resin component where, based on a total weight of the composite polymer material, the composite polymer material includes 10 to 40 wt.% of the filler, and where the composite polymer material has a post-anneal shrinkage of 0.01 to 0.9% and a coefficient of linear thermal expansion of 1.8xl0’5to 6.5xl05m / m / °C.

[0041] Example fillers are listed in Table 1 together with selected physical properties. Particulate fillers, such as calcium carbonate, talc, and calcium silicate, may be characterized by a mean particle size (d), particle size distribution (PSD), and bulk density (pbulk). By way of example, a filler may have a mean particle size of 0.1 to 20 micrometers, e.g., 0.1, 0.2, 0.5, 1, 2, 5, 10, 15, or 20 micrometers, including ranges between any of the foregoing values. Filler particle size may be evaluated in accordance with ASTM E3340. Filler particle size distribution may be evaluated in accordance with ASTM E1617 and ASTM C136 / C136M. Filler bulk density may be evaluated in accordance with ASTM D7481.

[0042] According to some embodiments, a composite building material may have a total filler content of approximately 10 to 40 percent by weight, e.g., 10, 15, 20, 25, 30, 35, or 40wt.%, including ranges between any of the foregoing values. A relative filler content, expressed as a ratio (wt.% / wt.%) with respect to the polymer content in the composite building material, may be 20 to 85, e.g., 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80, including ranges between any of the foregoing values.

[0043] Table 1. Example Fillers and their Physical PropertiesFiller d [pm] PSD Pbulk Pbulk Total Relative [kg / m3] [kg / m3] Loading Loading (loose) (compact) [wt.%] [X:PVC] CaCOs 0.7 < 1 pm - 65% 10-30% 20:100< 2 pm - 90%Talc 3.4 < 1 pm - 20% 240 801 10-20% 20:100< 5 pm - 65%CaSiOs 12 < 5 pm - 11% 224 481 20-40% 85:100< 10 pm - 40%

[0044] In some aspects of the disclosure, there is provided a use of a polymer resin matrix comprising a polymer resin, wherein the polymer resin comprises 25 to 100 wt.% recycled polymer, preferably recycled PVC polymer, based on a total polymer resin content; and a filler, preferably talc, CaCCh and / or CaSiOa, dispersed throughout the polymer resin matrix, wherein the polymer resin matrix comprises 10 to 40 wt.% of the filler, to decreasing the extent of permanent shrinkage in PVC building products.

[0045] A method of forming a composite polymer composition may include combining a polymer resin with one or more additives, where the polymer resin includes recycled content. In such a manner, the one or more additives may be independently added to the composite polymer composition. In addition to, or in lieu of, combining a polymer resin withindependently sourced additives, the recycle content within the polymer resin may include residual additives and / or fillers from prior processing. For instance, a source of recycled polymer may include filler in an amount sufficient that an independent addition of filler to a composite polymer composition may be avoided.

[0046] The recycled polymer, e.g., recycled PVC, may itself comprise residual fillers, residue foaming agents, residue thermal stabilizer, residue AO / UV and other additives. The residue fillers, in combination with the additional fillers added during product manufacture via extrusion may operate synergistically to help maintain the thermal stability of the product structures / form. The resulting performance improvements of both shrinkage reduction and increased heat resistance allow for significant installation opportunities during product use.

[0047] Further additives may include foaming agents, stabilizers, antioxidants, processing aids, and the like. Particularly in conjunction with PVC and other thermoplastic-based compositions, a foaming agent may be used to create a less dense, lighter building product while also improving certain performance characteristics such as thermal insulation and sound damping.

[0048] A function of a foaming agent in composite materials is to reduce the density of the material, which leads to a lighter product. This is particularly advantageous during installation, as lighter boards are easier to handle, transport, and cut. The foaming process also helps to lower material costs since less plastic is used while still maintaining structural integrity.

[0049] In some embodiments, one or more foaming process parameters may be controlled to achieve a target density in the resulting composite building product. Examplefoaming process parameters include temperature, the amount and type of filler, as well as the amount and type of foaming agent.

[0050] In addition to weight reduction, foaming agents can improve the thermal insulation properties of a composite building product, making it less prone to heat buildup in hot weather. This can be particularly important for creating comfortable outdoor living spaces, as it helps prevent a deck surface from becoming excessively hot under direct sunlight. Additionally, foamed composite decking boards may offer better sound insulation, reducing noise caused by foot traffic or objects dropping on the surface.

[0051] Without wishing to be bound by theory, foaming agents function by releasing gas during the extrusion process that creates small bubbles or voids within the material, thereby expanding its volume without significantly increasing the weight. The result is a cellular structure within the board. In some embodiments, a void diameter may be less than approximately 2.5 mm, e.g., 0.0025, 0.005, 0.025, 0.05, 0.25, or 0.5 mm, including ranges between any of the foregoing values. The cellularstructure of a porous polymer may be evaluated in accordance with ASTM D3576and ASTM D6226.

[0052] Foaming agents may include physical blowing agents and chemical blowing agents. Example foaming agents include azodicarbonamide, sodium bicarbonate, and hydrazinebased compounds, as well as combinations thereof. These agents decompose at elevated temperatures to release gas, creating a porous texture throughout the polymer matrix.

[0053] Further additives may include environmental stabilizers such as UV stabilizers, which may be adapted to protect the polymer material from the effects of ultraviolet (UV) radiation. UV radiation can cause discoloration, fading, and degradation of the polymercomponents in decking boards and other structural elements, so stabilizers like benzotriazoles or hindered amine light stabilizers (HALS) may be used to mitigate these effects and extend the material's lifespan. Antioxidants may also be used to inhibit or prevent oxidation, which can occur when a polymer is exposed to heat and oxygen, degrading its strength and appearance overtime.

[0054] To improve the fire resistance of composite decking, siding, trim and related products, fire retardants may be used. These compounds, such as aluminum hydroxide, magnesium hydroxide, and brominated chemicals, decrease the flammability of the material, making it safer, especially in fire-prone areas.

[0055] Processing aids, such as lubricants and plasticizers, may improve flowability during extrusion and molding, promoting a consistent finish and texture. Colorants and dyes may also be added to give decking boards and other composite products a desirable color, ranging from wood-like tones to a variety of other shades. Example colorants / dyes include iron oxides, titanium dioxide, and carbon black.

[0056] For added moisture resistance, some composite products contain additives that inhibit or prevent water absorption, which can cause warping, swelling, or mold growth. These can include silicone-based treatments or wax emulsions. Similarly, antimicrobial agents may be incorporated to prevent mold, mildew, and bacteria from growing on surfaces, especially in humid or wet environments.

[0057] To improve the toughness and impact resistance, impact modifiers such as styrene-butadiene rubber (SBR) or acrylic-based modifiers may be used. These may promote resistance to cracking or fracture under pressure.

[0058] A combination of polymer resin, filler(s), and one or more additional additives may achieve a synergistic effect that promotes profile dimensional stability in composite building products. Moreover, improvements in both shrinkage reduction and heat resistance may facilitate meaningful installation opportunities in the field, including longer product lengths, decreased trim pocket depths, darker color options, use in higher heat climates, and fewer installation restrictions.

[0059] In accordance with some embodiments, a composite building product includes a polymer resin matrix, where the polymer resin matrix is composed of 25 to 100 wt.% recycled polymer, and a filler dispersed throughout the polymer resin matrix. In some embodiments, the composite building product may be configured as trim, siding, decking board, fascia, or railing and exhibits a post-anneal shrinkage of 0.01 to 0.9% and a coefficient of linear thermal expansion of 1.8xl0'5to 6.5xl0’5m / m / °C (lxlO’5to 3.6xl0’5in / in / °F).

[0060] The following will provide, with reference to FIGS. 1-11, detailed descriptions of materials and methods related to the formation of composite polymer compositions having a high recycle polymer content, and the manufacture of building materials such as decking, siding, fascia, railing, or trim from such compositions. The discussion associated with FIG. 1 includes a description of a testing apparatus for evaluating the impact of annealing on composite building products. The discussion associated with FIGS. 2-5 includes a description of the influence of annealing history on the dimensional stability of composite boards. The discussion associated with FIGS. 6-8 includes a description of the influence of annealing history on the shrinkage of composite boards. The discussion associated with FIGS. 9-11 includes a description of criteria for incorporating recycled PVC content into a building composition.

[0061] An oven annealing protocol may be used to evaluate the thermally-induced shrinkage of a composite building product. In an example method, a length dimension of a sample composite building product having a nominal specified length is measured prior to annealing. The sample is then placed into a convection oven, heated to an annealing temperature, and held at the annealing temperature for an annealing time. After holding for the annealing time, the sample is removed from the oven and allowed to cool over a cooling time to ambient conditions. Following the cooling time, the length dimension of the sample is remeasured, and an amount of thermally-induced shrinkage is calculated from the pre- and postannealing length measurements according to E = — , where s = linear shrinkage and Al = lf-10,with If equal to the final (post-annealed) length and 10 equal to the initial (pre-annealed) length.

[0062] In various examples, samples such as decking or siding boards or strips (e.g., bevel or trim) may have a nominal initial length of approximately 30 cm, although greater or lesser initial lengths may be used. An annealing temperature and an annealing time may be approximately 70°C and approximately 24 hr, respectively, although the annealing conditions may be suitably modified. In some evaluations, the cooling time may be approximately 24 hrs.

[0063] According to some embodiments, a surface annealing protocol may be used to evaluate thermally-induced deformation of composite building product samples. In an example evaluation, full length (e.g., 7.3 m) composite boards are movably installed on a test wall within an environmental chamber and proximate to a facing bank of infrared (IR) lamps. An experimental apparatus for surface annealing including an array of infrared lamps located within an environmental chamber is shown schematically in FIG. 1.

[0064] FIG. 1 illustrates an example annealing apparatus 100 for evaluating thermally induced deformation and dimensional stability of composite building products. The apparatus 100 may include a mounting structure configured as a wall or wall section, such as a test wall, to which one or more composite building products 110 are mounted. In some embodiments, the composite building products 110 are elongate extruded profiles, such as siding boards, trim boards, fascia boards, decking boards, or railing components, that are installed on the wall in an arrangement representative of field installation, including butt joints between adjacent product lengths. The composite building products 110 may be mounted in a manner that permits thermal expansion and contraction, such as by using fasteners and / or slots configured to allow movement relative to the wall.

[0065] An irradiation assembly including one or more lamps 120 is positioned facing the mounted composite building products 110. The lamps 120 may be infrared (IR) lamps configured to radiatively heat an exposed surface of the composite building products 110 to a target annealing temperature. In some embodiments, the lamps 120 are arranged as a bank or array to provide substantially uniform radiative heating over a length and width of the mounted composite building products 110. The distance between the lamps 120 and the composite building products 110, and an intensity of the lamps 120, may be selected to achieve a desired surface temperature profile.

[0066] The lamps 120 are electrically coupled to control circuitry 130 configured to regulate operation of the lamps 120. The control circuitry 130 may be configured to control at least one of lamp power, lamp intensity, ramp rate, heating duration, and duty cycle, and may be configured to implement an annealing protocol including a ramp period, a soak period at theannealing temperature, and a cooling period. In some embodiments, the control circuitry 130 is configured to receive temperature feedback from one or more temperature sensors associated with the composite building products 110 and to adjust electrical power delivered to the lamps 120 to maintain a target temperature or temperature range during the soak period.

[0067] Following exposure to the lamps 120 and subsequent cooling, the composite building products 110 may be evaluated for dimensional changes, including length change and / or deformation proximate butt joints, to assess dimensional stability as a function of formulation and recycle content. In example evaluations, following an initial length measurement of the boards under ambient conditions, the chamber temperature is increased to an annealing temperature that is held for an annealing time. In some embodiments, an annealing temperature may be less than a glass transition temperature (Tg) of the composite building material. In certain evaluations, an annealing temperature of 60-82°C and an annealing time of 2-6 hr may be used, where a ramp time for heating the samples to the annealing temperature may be approximately 1-4 hr, although the annealing conditions may be suitably modified. After cooling to ambient conditions, the length dimension of the samples is re-measured, and an amount of thermally-induced shrinkage is calculated.

[0068] The effects of annealing on dimensional stability and shrinkage for extruded composite products having different PVC content are summarized in Table 2. As shown in Table 2, the polymer content of Example 1 includes 15 wt.% reground PVC addition. Example 1 includes approximately 20 wt.% mineral filler. The polymer content of Example 2, on the other hand, includes 40 wt.% recycled PVC. Example 2 includes approximately 25 wt.% mineral filler.

[0069] The mineral filler (talc) content of Examples 1 and 2 is determined using an ash content test, which involves heating a sample to a temperature effective to burn off volatile (polymer) content to the exclusion of non-volatile (mineral) content. A difference in the sample mass before and after heating can be equated to the talc content in the sample.

[0070] Table 2. Effects of Annealing on PVC-based Composite ProductsExample 1 Example 2 PVC Content 15% Regrind 40% Recycle Talc Content 20% 25%Heat Effect Temperature 74°C 82-88°CCLTE (AT~70°C) [cm over 3.7 m] 1 1Shrinkage - Oven Anneal (70°C) 0.4% 0.2%Shrinkage - Surface Anneal (70°C) 0.4% 0.15%0-70°C Unrestricted Total Movement (14.6 m) 1.2 0.8Gardner Impact [N-m] 7.1 6.8

[0071] The impact of annealing history on the dimensional stability of composite siding boards is depicted in FIGS. 2-5 and is summarized in Table 2 as the heat effect temperature. The heat effect temperature represents the annealing temperature for which visible discontinuity across butt joints is observed in a run of boards. That is, the heat effect temperature corresponds to the onset of thermally-induced deformation in a composite building product.

[0072] For the Example 1 composition, and with reference to FIGS. 2 and 3, the onset of product distortion, which is manifested by the appearance of an open seam between adjacent lengths of boards, is observed for the sample that was annealed at 160°F (70°C) (FIGS. 2B and 3B) and significant product distortion is observed for the sample that was annealed at 170°F (77°C) (FIGS. 2C and 3C). In contrast, and with reference to FIGS. 4 and 5, for the Example 2 composition, which includes an elevated recycle content, only minor cupping between adjacent lengths ofboards is observed for the sample that was annealed at 180°F (82°C)) (FIGS. 4D and 5D) whereas more visible product distortion is observed for the sample that was annealed at 190°F (88°C) (FIGS. 4E and 5E).

[0073] As will be appreciated, with reference to the illustrations corresponding to the low reground content samples of FIGS. 2 and 3, and the illustrations corresponding to the high recycle content samples of FIGS. 4 and 5, heat resistance as manifested by dimensional stability is improved by increasing the recycle content in the composite boards. In some embodiments, a composite building material may be adapted to have a heat build-up (ASTM 4803) of less than approximately 60°F (15.5°C).

[0074] A coefficient of linearthermal expansion (CLTE) may be measured using a light induced expansion (LIE) technique, which advantageously measures strain over an entire length of an extruded composite building product. A sample length may be 8, 10, 12, or 14 feet, for example. In an illustrative method, a cooled and substantially non-emissive sample is mounted and aligned on a measurement apparatus where it is initially allowed to warm to a surface temperature of approximately 0°F (-18°C) and is thereafter heated by exposure to solar radiation to a target surface temperature. A non-emissive sample may be painted black, for example. A cooled temperature may be approximately -45°C.

[0075] The measurement apparatus may include a solar simulator configured to irradiate and heat the sample surface to approximately 70°C, although lesser and greater target surface temperatures are contemplated. A linear dimension of the sample, e.g., length, is measured prior to cooling the sample, when the sample surface is at -20°C, when the sample surface is at the target surface temperature, and after cooling the sample to ambienttemperature (20°C). The sample's linear dimension may be measured using a laser. In some embodiments, a composite building material may be adapted to withstand surface heating to 70°C without evidencing any noticeable distortion, including loss of grain texture, oil canning, warping, etc.

[0076] Coefficient of linear thermal expansion data for both a low reground polymer content composite board (Example 1) and a high recycled polymer content composite board (Example 2) are summarized in Table 2 for boards having a length of 3.7 m. In some embodiments, a composite building material may exhibit a coefficient of linear thermal expansion (LIE technique-3.7 m sample) of less than approximately 2 cm, e.g., 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8 or 2 cm, including ranges between any of the foregoing values. In some embodiments, a composite building material may have a coefficient of linear thermal expansion (ASTM D6341) of less than approximately 6.5xl0-5m / m / °C, e.g., 1.8xl0'5, 2xl0'5, 2.5xl0-5, 3x10"5, 3.5xl0‘5, 4xl0‘5, 4.5xl0‘5, 5xl0‘5, 5.5xl0‘5, 6xl0‘5, or 6.5xl0-5m / m / °C, including ranges between any of the foregoing values.

[0077] Independent of the coefficient of thermal expansion, composite building products may undergo non-recoverable shrinkage upon heating. Observable shrinkage for boards including 15% reground PVC (Example 1) and 40% recycled PVC (Example 2) as a function of annealing history is shown in FIGS. 6 and 7, respectively.

[0078] Shrinkage data for composite boards processed to an annealing temperature of 70°C using an oven annealing protocol and a surface annealing protocol are summarized in Table 2. Relative to the low reground polymer content boards, the high recycled polymer content boards show an approximately 50% improvement in shrinkage performance. That is, shrinkagedue to annealing may be decreased by modifying the composite polymer composition to include greater amounts of recycled polymer.

[0079] According to some embodiments, a composite building material may have a post oven anneal (24 hr soak at 70°C following a ramp from 20°C) shrinkage of less than approximately 0.9%, e.g., 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, or 0.9%, including ranges between any of the foregoing values.

[0080] Referring initially to FIG. 6, shown are a series of images of low reground polymer content boards each having a different surface annealing history. Each board includes a 5.7 cm wide slot located proximate to its upper edge with a frame-mounted pin movably disposed within the slot. Prior to annealing, each pin is located at the approximate center of the slot and the pin position is marked. The annealing induced shrinkage of each board may be visualized in FIGS. 6A-6E with particular reference to the shifted location of each pin following a respective surface annealing protocol.

[0081] As seen in FIG. 6A, the pin location for the control board is approximately centered within the slot. Thermally-induced shrinkage is visible in each of FIGS. 6B-6E, with the pin location having traversed the entire slot width following surface anneals of 77°C or greater.

[0082] Turning to FIG. 7, shown are a seriesof images of high recycle polymer content composite boards each having a different surface annealing history. Annealing induced shrinkage of each board may be visualized in FIGS. 7A-7E with reference to the location of each pin following surface annealing.

[0083] The pin location for the control board is approximately centered within the slot, as shown in FIG. 7A. With particular reference to the pin displacement, thermally-inducedshrinkage of the high recycle content boards is visible in each of FIGS. 7B-7E. In contrast to the low regrind polymer content boards of FIG. 6, as shown in FIGS. 6B-6E, the pin location of the high recycle content boards has traversed less than the complete slot width for annealing temperatures up to 190°F (88°C), indicating a lesser amount of post-anneal shrinkage forthe high recycle content boards.

[0084] Referring again to Table 2, unrestricted total movement represents a calculated total deformation (i.e., linear shrinkage) due to both annealing and coefficient of thermal expansion effects for a 14.6 m length of building product. Relative to Example 1, the incorporation of additional filler and a higher recycle content into the composite building material of Example 2 decreases the total linear deformation of corresponding composite boards by approximately 35% without adversely affecting ambient Gardner Impact test results (ASTM D4226, D5420).

[0085] Referring to FIG. 8, the effect of recycle content on permanent shrinkage is illustrated for example composite trim products. An approximately 50% decrease in post-anneal shrinkage is observed by increasing the recycle content to 25% relative to products formed from virgin (non-recycled PVC). For trim products having 97% recycled content, the post-anneal shrinkage may be less than approximately 0.15%, e.g., 0.01, 0.02, 0.05, 0.1, or 0.15%, including ranges between any of the foregoing values.

[0086] In an example method of manufacture, incoming return polymer (RP) materials may be sorted, ground (12-20 mesh), and blended to produce a batch of recycle content. The recycle content may then be combined with non-recycle resin and the resulting highrecycle content mixture may be combined with one or more additives to form an extrusion batch that is fed into a feeder hopper of an extrusion apparatus.

[0087] Sustainable, low-maintenance building materials, including exterior products such as decking, trim, railings, siding, and cladding, may be made from reclaimed or repurposed materials, such as recycled polyvinyl chloride (PVC). As an alternative to natural wood, PVC-based materials may be more durable, weather-resistant, and eco-friendly.

[0088] Polyvinyl chloride (PVC) may be obtained from various waste streams, including regrind material from manufacturing scrap, recycled material from post-industrial and consumer sources, and reprocessed material from melted and reformulated waste.

[0089] According to some embodiments, a waste stream may include post-industrial waste, such as scrap, trimmings, excess material and / or defective products obtained from manufacturing processes.

[0090] According to some embodiments, a waste stream may include post-consumer waste, such as discarded PVC products (e.g., flooring, window frames, credit cards, shower curtains, inflatable toys, etc.).

[0091] In some embodiments, the generation of regrind, recycling, and reprocessing waste streams may include grinding scrap material into reusable particles, recovering discarded PVC products for reuse, and transforming waste into reprocessed raw material through melting and reformulation.

[0092] As used herein, a "regrind waste stream" for PVC may refer to scrap material that is generated during the manufacture or processing of PVC products, which may be groundand / or pulverized into smaller pieces for reuse. Regrind waste may be obtained from various sources, including production scrap, post-industrial waste, and / or post-consumer waste.

[0093] A "recycled waste stream" may refer to discarded PVC material that has been collected and processed for reuse.

[0094] A "reprocessed waste stream" may refer to discarded PVC material that has been collected, treated, and converted into usable raw material. The reprocessing may include one or more of sorting, cleaning, shredding, melting, and reformulating the waste to make it suitable for reuse.

[0095] Waste stream-sourced PVC, obtained from post-industrial or post-consumer waste streams, may be collected, sorted, cleaned, and ground into regrind material or reprocessed into pellets. This material may be mixed with virgin PVC resin in specific proportions, depending on the targeted performance characteristics of the building material. In some embodiments, PVC material from a waste stream may be combined with virgin PVC to manufacture building products through controlled blending and extrusion processes.

[0096] As a percentage by weight of the total PVC resin content in an extrudable mixture, the amount of PVC obtained from one or more waste streams may be 20% to 100% of the batch, e.g., 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99, or 100 wt.%, including ranges between any of the foregoing values. That is, in accordance with some embodiments, in an extrudable batch containing virgin PVC and PVC from one or more waste streams, the amount of PVC from the one or more waste streams may constitute 20 to 99% of the resin content in the batch. According to some embodiments, an extrudable batch may includeonly PVCfrom one or more waste streams, i.e., to the exclusion of virgin PVC. In such examples, the PVC content includes 100% waste stream-sourced PVC.

[0097] The suitability of a single waste stream or a blend including one or more waste streams for the manufacture of a PVC building material may be evaluated in the context of the building product (e.g., decking, trim, railings, siding, cladding, etc.) and its targeted performance attributes. A waste stream or waste stream-containing mixture may be chosen using one or more selection criteria, which may include selected mechanical, thermal, and rheological properties.

[0098] As will be appreciated, building products manufactured from a single waste stream may not achieve desired performance characteristics. In some embodiments, to attain the desired properties, a building product may be produced using a blend of materials that include virgin PVC and PVC content from one or more waste streams.

[0099] In some examples, an extrudable batch of PVC material may include virgin PVC and PVC from a single waste stream. In some examples, an extrudable batch of PVC material may include virgin PVC and PVC from two or more waste streams. By mixing PVC resins from different sources, the processability of the blend, economics of manufacture, and properties of the resulting building material may be tuned to achieve the desired performance.

[0100] In some embodiments, an extrudable batch of PVC may include a mixture of virgin PVC and waste stream-sourced PVC. In such examples, the polymer component of the batch may include 0 to 97.5 wt.% virgin PVC and 2.5 to 100 wt.% PVC from one or more waste streams. As amongst the waste stream-sourced PVC, in an example ternary system, the relative amounts of PVC from a first waste stream and PVC from a second waste stream may range from 1 to 99 wt.% and from 99 to 1 wt.%, respectively.

[0101] In some embodiments, expressed as a percentage of the total resin content in a PVC blend, the amount of virgin PVC may range from 0 to 97.5 wt.%, e.g., 0, 2.5, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97.5 wt.%, including ranges between any of the foregoing values, while the amount of PVC from a first waste stream, and optionally the amount of PVC from a second waste stream may independently range from 2.5 to 100 wt.%, e.g., 2.5, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97.5%, or 100 wt.%, including ranges between any of the foregoing values.

[0102] The engineering of an extrudable PVC resin blend may include evaluating a building product formed from the constituent resins independently or from the resin mixture. In an extrusion process for forming a PVC building product, resin and additives may be transformed from a granular or powdery state into a homogeneous melt. Melting, fusion and extrusion may follow a sequence influenced by temperature, shear, and time. Initially, PVC particles compact and soften as they are fed into the extruder, with heat and pressure promoting partial coalescence. As mechanical energy from the extruder screw generates shear forces, the particles further break down and begin to fuse, increasing torque as the material resists flow.

[0103] With continued shear and heat input, the material may reach a state of full fusion, where particles merge into a continuous melt, allowing for proper molecular entanglement. At this stage, torque stabilizes or slightly decreases, indicating the material has reached a stable, processable state. Once fully fused, the melt may be extruded through a die to form a building product.

[0104] Example batch compositions including virgin PVC and PVC from a first waste stream are shown in Table 3. By blending a virgin stream with the first waste stream, the thermalstability of the blend may be improved relative to the waste stream alone. In some embodiments, building products formed from the blend may have a DTS time of 30-40 min, e.g., 30, 35, or 40 min, including ranges between any of the foregoing values. In some embodiments, the combination of PVC from a first waste stream with virgin PVC to form a binary resin blend may improve the economics of manufacture.

[0105] Dynamic thermal stability (DTS) time, dynamic thermal stability (DTS) torque, and equilibrium torque, which may be treated as the steady-state (plateau) torque after fusion, may be measured on a torque rheometer (e.g., a Brabender / Haake mixer) in accordance with ASTM D2538.

[0106] Table 3. Compositions and Rheological Properties of Binary Resin Blends Virgin PVC Waste Stream DTS Time DTS Torque Eq. Torque[%] [%] [min] [N-m] [N-m] 100 — 43.7 34.3 21.1 80 20 35.2 36.8 22.2 60 40 30.1 35.7 22.4 50 50 29.2 34.8 22.5 40 60 26.3 34.8 22.4 20 80 21.9 33.4 21.5 — 100 18.0 31.4 20.6

[0107] The kinetics of fusion and melting for different PVC resins and resin blends are shown graphically in FIG. 9, which is a plot of torque versus time highlighting variations in shear resistance, fusion time, and melt viscosity as each composition reacts to thermal and shear forces during extrusion. During torque rheometry or extrusion, the torque initially rises as PVC particlesundergo fusion, then gradually decreases as the material becomes fully melted and homogenized. Once a stable melt state is reached, the torque plateaus, indicating equilibrium.

[0108] Baseline curve 10 in FIG. 9 shows the fusion response for a comparative material where the resin content includes 100% virgin PVC. Curve 10 includes a transition response region 12, a fusion region 14, and an equilibrium response region 16. According to some embodiments, the replication of baseline curve 10, including the amplitude and temporal location of fusion region 14 may provide an indicia of suitability of alternate resins and resin mixtures, including blends of virgin PVC and PVC from one or more waste streams, for manufacturing an extruded building product. When different PVC resins exhibit similar fusion behavior, they may provide processing advantages during extrusion by maintaining consistent flow, shear response, viscosity, and the like. This consistency ensures that the extrusion machine parameters, such as screw speed, temperature profile, and pressure settings, need not be adjusted when switching between resins.

[0109] As shown in FIG.9, curve 100 represents the fusion response fora PVC material derived from a first waste stream (Waste Stream 1). Relative to baseline curve 10, it will be appreciated that the fusion region 104 of curve 100 is displaced to shorter times and the equilibrium region 106 is offset to lesser torque values, likely indicating fundamentally different fusion kinetics for the virgin and first waste stream materials.

[0110] Curve 200 represents the fusion response for a PVC material derived from a second waste stream (Waste Stream 2). Comparing curve 200 with baseline curve 10, the fusion response, including the temporal location of the fusion region, as well as the long termequilibrium response, are indicative of similar fusion kinetics for the virgin and second waste stream materials.

[0111] Notwithstanding the differences in the processability of Waste Stream 1 (curve 100) relative to the virgin PVC (curve 10), Applicant has shown that blended resins including virgin PVC, PVC from the first waste stream, and PVC from the second waste stream may be extruded to form commercially-relevant building products. That is, although a first waste stream may itself be unsuitable as a source of PVC, in some embodiments a building product may be formed from an engineered mixture containing the first waste stream, a second waste stream, and optionally virgin PVC.

[0112] Example batch compositions including virgin PVC, PVC from a first waste stream, and PVC from a second waste stream are shown in Table 4. In some embodiments, the combination of PVC from a first waste stream and PVC from a second waste stream with virgin PVC to form a ternary resin blend may improve the economics of manufacture of a building product. Fusion curves corresponding to the data in Table 4 are plotted in FIG. 9.

[0113] Table 4. Compositions and Rheological Properties of Ternary Resin Blends Virgin PVC Waste Stream 1 Waste Stream 2 DTS Time DTS Torque Eq. Torque [%] [%] [%] [min] [N-m] [N-m] 100 — — 50 18.5 24— 100 — 14 14.5 21.6— — 100 24 21.4 23.395 2.5 2.590 5 5 22.890 2.5 7.5 44 18.5 22.980 2.5 17.580 10 1080 15 575 5 20 39 19 23.275 12.5 12.5 23.270 15 1550 10 30 33 19.5 22.850 15 2550 20 2050 10 40 30 19.7 22.850 25 2540 10 50 28 20.1 22.840 20 4040 30 3030 20 5030 30 4025 10 65 24 20.5 22.925 30 4520 10 7020 30 5020 40 4010 10 80 22 21 2310 20 7010 30 6010 40 505 15 805 45 50

[0114] With reference to Tables 3 and 4, dynamic thermal stability (DTS) refers to the ability of a PVC material to resist thermal degradation when exposed to heat and shear forces during processing, such as extrusion or injection molding. Due to its heat sensitivity, PVC may degrade when exposed to elevated temperatures, which may lead to dehydrochlorination, discoloration, and loss of mechanical properties.

[0115] Under dynamic conditions, where both heat and mechanical stress may be applied, stability may depend on factors including temperature, shear rate, processing time, and formulation additives. In some embodiments, heat stabilizers (e.g., tin-based, calcium-zinc, or lead stabilizers) may be added to resin formulations to inhibit early degradation by neutralizing HCI release and preserving molecular structure.

[0116] Turning to FIG. 10, shown is a plot of the dynamic thermal stability (DTS) of selected PVC resin compositions, including virgin PVC, PVC material derived from a first waste stream (Waste Stream 1), PVC material derived from a second waste stream (Waste Stream 2), and ternary PVC blends of the foregoing in accordance with some embodiments. Dynamic thermal stability (DTS) data are summarized in Table 4 and indicate that blended combinations of virgin PVC, PVC from a first waste stream, and PVC from a second waste stream may achieve DTS times in excess of 20 minutes, e.g., 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, or 44 minutes, including ranges between any of the foregoing values. Longer DTS times indicate greater thermal stability.

[0117] Referring still to Tables 3 and 4, dynamic thermal stability torque in PVC processing refers to the torque behavior of the material over time under heat and shear conditions during mixing or extrusion. It may be an indicator of how PVC formulations resist thermal degradation when subjected to continuous processing forces.

[0118] Higher dynamic thermal stability torque may indicate that the PVC resin can withstand longer processing times without excessive viscosity changes, degradation, or discoloration. This may be significant during processing, such as extrusion, calendering, and injection molding, where consistent melt behavior may provide uniform product quality. In someembodiments, a building material formed from PVC may have a dynamic thermal stability (DTS) torque of at least 15 N-m, e.g., 15, 16, 17, 18, 19, 20, 21, 22, or 23 N-m, including ranges between any of the foregoing values. The dynamic thermal stability torque data are summarized in Table 4 for selected PVC resin compositions.

[0119] Equilibrium torque in PVC processing refers to the steady-state torque measured during continuous mixing or extrusion when the material has fully fused and reached a stable melt viscosity. It may indicate how much resistance the PVC melt provides against the rotating screws or mixing blades under certain processing conditions. In some embodiments, a building material formed from PVC may have an equilibrium torque of at least 23 N-m, e.g., 23, 24, or 25 N-m, including ranges between any of the foregoing values. Equilibrium torque data for selected PVC resin compositions are summarized in Table 4.

[0120] Plots of dynamic thermal stability (DTS) time and dynamic thermal stability (DTS) torque for selected PVC resins are shown in FIG. 11A and FIG. 11B, respectively. The graphs illustrate the effects of combining different amounts of virgin PVC, PVC from a first waste stream, and PVC from a second waste stream on rheological properties such as viscosity, torque, and melt flow behavior.

[0121] Composite polymer building products, such as trim, siding, decking boards, fascia, and railing, are provided that use a high proportion of recycled thermoplastic polymer, particularly recycled polyvinyl chloride, to improve dimensional stability when exposed to elevated temperatures.

[0122] In disclosed embodiments, a polymer resin matrix includes about 25 to 100 wt.% recycled polymer and a dispersed filler (for example, mineral fillers such as talc, calciumcarbonate, wollastonite, or mica) in an amount effective to reduce thermal movement while maintaining extrudability. The resulting composite products exhibit reduced permanent, non-recoverable shrinkage after thermal exposure (post-anneal shrinkage) and a relatively low coefficient of linear thermal expansion, which together reduce installation gaps, warping, and heat-induced deformation.

[0123] Recycled polymer feedstocks may have undergone prior thermal cycles that effectively "pre-anneal" the material, lowering internal stresses and reducing shrinkage in the final extruded profiles without requiring a separate post-extrusion annealing step. Methods are also described for blending recycled and optional virgin resin with filler and additives and extruding the formulation, as well as for selecting or engineering resin blends (including blends from different waste streams) using processing and thermal stability criteria such as dynamic thermal stability time / torque and equilibrium torque to support stable processing and consistent product performance.

[0124] In another aspect, the disclosure relates to use of recycled polymer material(s), alone or in combination with one or more functional filler materials, as means to obviate the need for a secondary annealing process during manufacture of an extruded composite polymer building product. Use of recycled polymers comprising annealed polymers, particularly in combination with functional fillers in the recycled material, may be advantageous.

[0125] The process parameters and sequence of the steps described and / or illustrated herein are given by way of example only and can be varied as desired. For example, while the steps illustrated and / or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order illustrated or discussed.The various exemplary methods described and / or illustrated herein may also omit one or more of the steps described or illustrated herein or include additional steps in addition to those disclosed.

[0126] The preceding description has been provided to enable others skilled in the art to best utilize various aspects of the exemplary embodiments disclosed herein. This exemplary description is not intended to be exhaustive or to be limited to any precise form disclosed. Many modifications and variations are possible without departing from the spirit and scope of the present disclosure. The embodiments disclosed herein should be considered in all respects illustrative and not restrictive. Reference should be made to the appended claims and their equivalents in determining the scope of the present disclosure.

[0127] As used herein, the term "substantially" in reference to a given parameter, property, or condition may mean and include to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a small degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least approximately 90% met, at least approximately 95% met, or even at least approximately 99% met.

[0128] As used herein, the term "approximately" in reference to a particular numeric value or range of values may, in certain embodiments, mean and include the stated value as well as all values within 10% of the stated value. Thus, by way of example, reference to the numeric value "50" as "approximately 50" may, in certain embodiments, include values equal to 50±5, i.e., values within the range 45 to 55.

[0129] Unless otherwise noted, the terms "connected to" and "coupled to" (and their derivatives), as used in the specification and claims, are to be construed as permitting both direct and indirect (i.e., via other elements or components) connection. In addition, the terms "a" or "an," as used in the specification and claims, are to be construed as meaning "at least one of." Finally, for ease of use, the terms "including" and "having" (and their derivatives), as used in the specification and claims, are interchangeable with and have the same meaning as the word "comprising."

[0130] It will be understood that when an element such as a layer or a region is referred to as being formed on, deposited on, or disposed "on" or "over" another element, it may be located directly on at least a portion of the other element, or one or more intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly over" another element, it may be located on at least a portion of the other element, with no intervening elements present.

[0131] While various features, elements or steps of particular embodiments may be disclosed using the transitional phrase "comprising," it is to be understood that alternative embodiments, including those that may be described using the transitional phrases "consisting of" or "consisting essentially of," are implied. Thus, for example, implied alternative embodiments to a filler that comprises or includes calcium carbonate include embodiments where a filer consists essentially of calcium carbonate and embodiments where a filler consists of calcium carbonate.

Claims

WHAT IS CLAIMED IS:

1. A composite building product, preferably an extruded composite building product, comprising:a polymer resin matrix comprising a polymer resin,wherein the polymer resin comprises 25 to 100 wt.% recycled polymer, preferably recycled PVC polymer, based on a total polymer resin content; and a filler, preferably an inorganic filler such as talc, CaCOs and / or CaSiOs, dispersed throughout the polymer resin matrix,wherein the polymer resin matrix comprises 10 to 40 wt.% of the filler, wherein the composite building product has a post-anneal shrinkage of 0.01 to 0.9%, and a coefficient of linear thermal expansion of 1.8xl0-5to 6.5xl0-5m / m / °C.

2. The composite building product of claim 1, wherein the polymer resin comprises 95 to 100 wt.% of the recycled polymer.

3. The composite building product of claim 1 or claim 2, wherein the polymer resin comprises a thermoplastic polymer selected from the group consisting of polyvinyl chloride, polypropylene, and polyethylene.

4. The composite building product of any one of claims 1 to 3, wherein the filler comprises at least one compound selected from the group consisting of wood flour, calcium carbonate, talc, wollastonite, and mica.

5. The composite building product of any one of the preceding claims, wherein the filler is dispersed homogeneously throughout the polymer resin matrix.

6. The composite building product of any one of the preceding claims, wherein the filler has a mean particle size of 0.1 to 20 micrometers measured according to ASTM E3340.

7. The composite building product of any one of the preceding claims, wherein the filler comprises an inorganic filler.

8. The composite building product of any one of the preceding claims, wherein the polymer resin matrix further comprises a thermal stabilizer.

9. The composite building product of any one of the preceding claims, wherein the polymer resin matrix further comprises a processing aid.

10. The composite building product of any one of the preceding claims, wherein the polymer resin matrix further comprises a foaming agent.

11. The composite building product of any one of the preceding claims, wherein the building product comprises a form factor selected from the group consisting of trim, siding, decking board, fascia, and railing.

12. The composite building product of any one of the preceding claims, wherein the recycled polymer comprises a thermoplastic polymer.

13. The composite building product of any one of the preceding claims, wherein the recycled polymer comprises recycled polyvinyl chloride having a K value of 60 to 80, and wherein the recycled polyvinyl chloride comprises at least one of rigid polyvinyl chloride or foamed polyvinyl chloride.

14. The composite building product of any one of the preceding claims, wherein the composite building product exhibits a dynamic thermal stability time of at least 20 minutes, a dynamic thermal stability torque of at least 15 N-m, and an equilibrium torque of at least 23 N-m.

15. The composite building product of any one of the preceding claims, wherein the recycled polymer includes residual inorganic filler, wherein a relative filler loading expressed as a ratio of filler to polymer is 20 to 85, and wherein the composite building product has at least one of (i) a heat build-up, measured according to ASTM 4803, of less than 15.5°C, (ii) a heat effect temperature of at least 82°C, or (iii) an unrestricted total movement over 48 feet between 0°C and 70°C of less than 8 cm.

16. A method comprising:combining a polymer resin and a filler, preferably an inorganic filler such as talc, CaCOs and / or CaSiOa, to form a polymer formulation,wherein the polymer resin comprises 25 to 100 wt.% recycled polymer, preferably recycled PVC polymer; andextruding the polymer formulation to form a composite building product,wherein the composite building product has a post-anneal shrinkage of 0.01 to 0.9% and a coefficient of linear thermal expansion of 1.8xl0-5to 6.5xl0‘5m / m / °C.

17. The method of claim 16, wherein the polymer resin comprises 95 to 100 wt.% of the recycled polymer.

18. The method of claim 16 or claim 17, wherein a total amount of filler in the polymer formulation is greater than an amount of the filler combined with the polymer resin.

19. The method of any one of claims 16 to 18, wherein the recycled polymer comprises an inorganic filler such as talc, CaCOa and / or CaSiOa.

20. The method of any one of claims 16 to 19, wherein the composite building product comprises a form factor selected from the group consisting of trim, siding, decking board, fascia, and railing.

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