Fiber reinforced polymer composites and articles made therefrom

Abstract

A pultruded fiber reinforced polymer composite having a blend of a conventional pultruded resin and a rigid sol is disclosed. Rigid sol is used for replacing some conventional pultrusion resin, so that the adverse effect on the mechanical property is avoided, but the affinity of a pultrusion part to a covering material containing polyvinyl chloride is really improved.

Description

[0001] Priority claim

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 62 / 366,764 (Attorney Docket No. 12016024), filed on July 26, 2016, which is incorporated herein by reference. Field of the Invention

[0003] The present invention relates to the use of rigid sol coated fibers for pultrusion of plastic articles. Background Art

[0004] Plastics have replaced other materials in a variety of industries. In the packaging industry, plastics have replaced glass to minimize breakage, reduce weight, and reduce energy consumed during manufacturing and transportation. In other industries, plastics have replaced metals to minimize corrosion, reduce weight, and provide products in bulk colors. More recently, an entire industry has emerged involving fiber reinforcement of polymer composites, sometimes referred to as "fiber reinforced polymer composites" (FRP composites).

[0005] FRP composites manufactured by standard pultrusion processes typically use thermosetting resins which allow high processing speeds but do not allow good bonding to the thermoplastic capstock.

[0006] Thermoplastic pultrusion, on the other hand, provides products with good bonding characteristics, but is slow to process and commercially unviable for certain industrial-scale applications. SUMMARY OF THE INVENTION

[0007] What is needed in the art is an FRP composite that can achieve all of the good bonding or affinity characteristics of a thermoplastic cover material, excellent processing speeds, and excellent resistance to heat distortion beyond the limits of the testing machines.

[0008] The work disclosed herein addresses a need in the art by using specially formulated thermoset-thermoplastic hybrid resin blends to achieve a desired balance of physical properties.For purposes of this invention, a rigid sol is considered a thermoplastic because it is processed as a thermoplastic prior to curing.

[0009] One aspect of the present invention is a fiber reinforced polymer composite material comprising (a) reinforcing fibers; (b) a rigid sol having a Brookfield viscosity of about 1200-3000 centipoise (ASTM D1824 25°C, 20 rpm), and (c) a pultrusion resin selected from polyesters, vinyl esters, epoxy resins and combinations thereof, wherein the reinforcing fibers are pultruded by the rigid sol and the pultrusion resin.

[0010] Another aspect of the present invention is a pultruded article made from the composite material.

[0011] Another aspect of the invention is a combination of a pultruded shaped article and a covering material having an affinity for the shaped article.

[0012] Embodiments will become apparent from the description of embodiments of the invention in conjunction with the following drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 These are photographs of an experiment related to Comparative Example A.

[0014] Figure 2 is a photograph of the same experiment as Example 1. DETAILED DESCRIPTION

[0015] Fiber reinforcement

[0016] One of ordinary skill in the art of thermoset pultrusion will recognize candidates for fiber reinforcement in the composite material of the present invention. Non-limiting examples of candidates for reinforcing fibers include: glass, steel, carbon, polyaramid ( fiber), silicon carbide, quartz, cellulose, juke, hemp, sisal, basalt, and combinations thereof.

[0017] Among these candidates, there are several excellent choices for glass fiber, including S-2 glass, S-1 glass, ECR glass, AR glass, D glass, R glass and E glass, used alone or in combination. Among these commercial glass fiber products, PPG Hybon9312, PPG Hybon 2662, PFG 1712, Jushi E6DR30-312T, OC Advantex SE8400 LS and PPG Innofiber 2026 are particularly preferred because they have the following physical properties:

[0018] The diameter of each fiber may range from about 13 μm to about 35 μm, preferably from about 13 μm to about 28 μm.

[0019] The yield per fiber roving may range from about 52 yield (9600 tex) to about 1650 yield (300 tex).

[0020] The tensile strength (ASTM D2343) may be about 300 kilopounds per square inch (Ksi) to about 450 Ksi, preferably about 350 Ksi to about 400 Ksi.

[0021] The tensile modulus (ASTM D2343) may be from about 10 megapounds per square inch (Msi) to about 12 Msi, preferably from about 10.5 Msi to about 11.5 Msi.

[0022] The tensile strain (ASTM D2343) may be from about 2% to about 4%, preferably from about 2.5% to about 3.5%.

[0023] Conventional pultrusion resin

[0024] 31020 is a highly reactive isophthalic polyester resin designed for the pultrusion process. This resin is suitable for pultrusion composites up to 3 / 8" thick with a glossy, fiber-free surface and fast line speeds. This resin has a high heat deflection temperature, excellent chemical and water resistance, good mechanical property retention at elevated temperatures, is 100% compatible with polyvinyl acetate, and offers fast line speeds, high gloss, and consistent performance from batch to batch.

[0025] Other conventional pultrusion resin candidates include polyesters, vinyl esters, and epoxies, which become thermoset when initiated during the pultrusion two-zone manufacturing process. Commercially advantageous conventional resins include, but are not limited to, Aropol L-2450 and Aropol L-2452 unsaturated polyester resins, DERAKANE 411 and DERAKANE 440 epoxy vinyl ester resins, and HETRON D-1398 and HETRON D-1222 epoxy vinyl ester resins, all from Ashland Inc.; and Dion 31020, Dion 31022, Dion 31069, Dion 31071, Dion 31052, and Dion 31830 vinyl ester resins from Reynolds LLC.

[0026] Rigid sol resin

[0027] Rigid sols useful in the present invention are those formed from dispersion, microsuspension and emulsion grades of poly(vinyl chloride) (PVC) resins (homopolymers and copolymers) and plasticizers. Exemplary dispersion grade PVC resins are disclosed in U.S. Pat. Nos. 4,581,413; 4,693,800; 4,939,212; and 5,290,890, as well as many other references such as those mentioned in the above four patents.

[0028] Ideally, when melting the PVC resin particles, the rigid sol is formulated to be rigid rather than flexible. Sometimes, these types of rigid sols are called "rigid sols" to emphasize that although they have begun to be used as flowable resins, they are rigid plastics after melting.

[0029] Desirable rigid sols in the present invention are those having a Shore D hardness (ASTM D2240-02, after 15 seconds) greater than about 60, preferably greater than 70 when molten. In addition, desirable rigid sols may have a tensile strength (ASTM D638) greater than about 7000 psi (48 MPa), preferably greater than 8000 or 9000 psi (55-62 MPa) when molten. Finally, desirable rigid sols exhibit only a small amount of elongation (ASTM D638) less than 10%, preferably less than 5% when molten.

[0030] Currently, the preferred rigid sol for use in the present invention is available from PolyOne Corporation as Geon TM MB2756 natural rigid sol acrylate modified polyvinyl chloride and from Zeon Technologies (Salisbury, NC, USA) as Pultuff TM Those commercially available as SULFATE® brand rigid sol resins are used in structural composite applications.

[0031] Suitable grades are identified as rigid non-phthalated rigid sols with low viscosity (Brookfield viscosity (ASTM D1824 25°C, 20 rpm) of about 1200-3000 centipoise).

[0032] Optional functional additives

[0033] Pultrusion formulations typically include more than just resin and plasticizer. Non-limiting examples of functional additives that may also be present in the pultrusion formulations of the present invention include: thermal stabilizers, UV absorbers, fillers, mold release agents, biocides, initiators, pigments, and combinations thereof. These functional additives are available from many commercial sources known in the plastics industry and may also be present in commercially available rigid sols, such as the Geon® described above. TM and Pultuff TM Resin.

[0034] Table 1 shows acceptable, desirable and preferred composition ranges that can be used in the present invention, all expressed as weight percent (wt%) of the entire mixture. The mixture may comprise, consist essentially of, or consist of these ingredients. The values ​​between any of the described range endpoints are also contemplated as the endpoints of a range, so that all possible combinations are within the possible ranges shown in Table 1 as candidate mixtures used in the present invention.

[0035]

[0036] The pultrusion process is a continuous forming process in which resin-impregnated reinforcements enter a mold from which they form a web and exit the mold cavity, preferably as a finished part. For thermoset pultrusion processes, all curing of the resin should take place inside the mold.

[0037] Practicality of the Invention

[0038] The flexural modulus (ASTM D790) of the FRP unidirectional composites of the present invention may be at least 4 Msi (27.5 GPa), may exceed 7 Msi (48.2 GPa), and has been found to exceed 8 Msi (55.2 GPa) at 80 wt% glass fiber loading.

[0039] The heat deformation temperature exceeds 75°C, and when there is a high loading of glass fiber in the FRP composite, the heat deformation temperature can exceed 87°C or even 100°C.

[0040] The structural strength of the FRP composite of the present invention allows the FRP composite to be useful in heavy load bearing structural capabilities. The use of a rigid sol does not reduce this load bearing performance, but increases the affinity for PVC containing covering materials, which is not available in traditional thermosetting FRP composite formulations.

[0041] Non-limiting examples of FRP composite uses include: exposed wall studs, truss supports, beams, windows, doors, fascias, siding, trim, etc., as well as conventional uses of FRP composites in construction such as trim, fencing, decorative non-load bearing accessories, etc. Any of these conventional products and parts made from FRP composite formulations can now benefit from the affinity of this form factor FRP composite formulation with PVC-containing covering materials.

[0042] The appearance of the FRP composite of the present invention can be determined by the shape of the extrusion die from which the FRP composite emerges after the pultruded fibers are coated with a blend of two resins, one thermosetting resin and another curable thermoplastic. Typically, the FRP composite has a smooth surface, but other additives may also be included to provide a finely mottled nonwoven fiber appearance.

[0043] Customers can also request pultruded FRP composite formulations in a variety of custom shapes and sizes to best meet their needs. Depending on the desired stiffness, weight, strength, flex, density, and tensile requirements, a person of ordinary skill in the art can develop a custom FRP composite without undue experimentation. Composite products can be manufactured using glass fiber reinforced plastics in mat / roving (MR-GFRP) or unidirectional (U-GFRP) designs. High-performance carbon fiber unidirectional reinforcements are also available.

[0044] Example

[0045] Table 2 shows the ingredients for making pultruded glass fiber reinforced polymer composites. A conventional pultrusion resin was used as Comparative Example A, where the resin was mixed with a rigid sol to demonstrate the value of the pultrusion resin blend of the present invention.

[0046]

[0047]

[0048] The only difference between the formulation and pultrusion of Comparative Example A and Example 1 was the replacement of 80% of the conventional pultrusion resin with a rigid sol.

[0049] To test the affinity of the pultrusion formulation to a polyvinyl chloride-containing cover material, a pultruded part made from the formulation in Comparative Example A having an area of ​​0.390 inches by 0.090 inches (0.99 cm by 0.23 cm) and then cut into sections 18 inches (46 cm) in length was compression molded with a 0.787 inch (2 mm) thick polyvinyl chloride (PVC) sheet made from Geon™ 87180 cover material. The compression molding temperature was high enough to melt the PVC. The compression force was 30 tons (266,893 Newtons). The purpose was to determine if the PVC sheet adhered or adhered to the pultruded part of Comparative Example A. Upon demolding, gravity caused the PVC sheet to immediately fall from the pultruded part. There was no evidence of adhesion or bonding or other affinity between the two parts of different material compositions. Figure 1 A photo of the results is shown.

[0050] The same affinity test was performed in a pultruded part of the same size and shape using the formulation of Example 1. The same compression molding was used; the same molding temperature was used. Upon demolding, the PVC sheet could not fall off the pultruded part even with average manual force.

[0051] Without being limited to a particular theory, it is believed that the presence of the PVC-containing rigid sol in the surface of the pultruded product allows for at least physical affinity for bonding of similar materials (two types of PVC) at the interface between the PVC sheet and the PVC-containing pultruded part during high temperature compression molding.

[0052] The implications of this simple comparison are not trivial. Pultrusion fabrication of fiber-reinforced polymer parts with an affinity for polyvinyl chloride allows for greater use of pultruded parts as building and construction materials (e.g., window frames) and for PVC-containing sheets used as aesthetic covering materials.

[0053] For example, the building material can be an article comprising the composite material disclosed herein in a pultruded shape, selected from the group consisting of: wall rivets, truss supports, beams, window components, door components, panels, siding, trim, decking, fencing and decorative non-load-bearing accessories, all covered by a polyvinyl chloride covering material.

[0054] Because pultrusion technology can produce two-dimensional parts of any conceivable length, and because PVC covering materials can be applied to the pultruded parts after pultrusion, a wide range of building and construction material manufacturing can be done, benefiting both suppliers and customers.

[0055] The present invention is not limited to the above described embodiments. See the appended claims.

Claims

1. A fiber-reinforced polymer composite material comprising: (a) reinforcing fibers, (b) a rigid sol having a Brookfield viscosity (ASTM D1824 25°C, 20 rpm) of about 1200-3000 centipoise, and (c) a pultrusion resin selected from polyester, vinyl ester, epoxy resin and combinations thereof, Wherein, the reinforcing fiber is pultruded by the rigid sol and the pultrusion resin.

2. The composite material according to claim 1, wherein The rigid sol has the following properties when melted as a resin: (1) Shore D hardness (ASTM D2240-02 after 15 seconds) exceeds 60, (2) Tensile strength (ASTM D638) exceeds about 48 MPa, (3) Percent elongation (ASTM D638) less than 10%.

3. The composite material according to claim 1 or 2, wherein: The reinforcing fibers are selected from the group consisting of glass, steel, carbon, polyaramid, silicon carbide, quartz, cellulose, polycarbide, hemp, sisal, basalt, and combinations thereof.

4. The composite material according to claim 3, wherein The glass fiber is selected from the group consisting of: S-2 glass, S-1 glass, ECR glass, AR glass, D glass, R glass, E glass and combinations thereof.

5. The composite material according to any one of claims 1 to 4, wherein The diameter of each reinforcing fiber is about 13 μm to about 35 μm.

6. The composite material according to any one of claims 1 to 5, wherein The reinforcing fibers have the following properties: (a) a yield of about 52 yield to about 1650 yield per fiber roving; (b) a tensile strength (ASTM D2343) of about 300 to about 450 kilopounds per square inch; (c) a tensile modulus (ASTM D2343) of from about 10 to about 12 megapounds per square inch; and (d) Tensile strain (ASTM D2343) is from about 2% to about 4%.

7. The composite material according to any one of claims 1 to 6, wherein The composite material further comprises a heat stabilizer, a UV absorber, a filler, a mold release agent, a biocide, a pigment or a combination thereof.

8. The composite material according to any one of claims 1 to 7, wherein The pultrusion resin is an isophthalic polyester resin.

9. The composite material according to any one of claims 1 to 8, wherein The composite material comprises 60-70 wt % of reinforcing fibers, 20-30 wt % of rigid sol and 5-7 wt % of pultrusion resin.

10. A pultruded article formed from the composite material according to any one of claims 1 to 9.

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