WO2008088782A1

WO2008088782A1 - Access floor support structure

Info

Publication number: WO2008088782A1
Application number: PCT/US2008/000470
Authority: WO
Inventors: Bruce Mcquilken; Marek Gnatowski
Original assignee: Byrne, Norman, R.
Priority date: 2007-01-12
Filing date: 2008-01-14
Publication date: 2008-07-24
Also published as: CA2675226A1; MX2009007517A

Abstract

An improved access floor support structure for an access floor system made of recyclable polypropylene with a mineral filler added thereto which increases the structure's mechanical properties. In one embodiment, the mineral filler is talc. In another embodiment, the mineral filler is montmorillonite clay. The montmorillonite clay is especially useful due to its additional fire retardant properties. Optional polypropylene additives may also be used to enhance the mechanical properties of the support structure.

Description

ACCESS FLOOR SUPPORT STRUCTURE

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of United States Provisional Patent Application Serial No. 60/880,096 filed January 12, 2007.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable. REFERENCE TO MICROFISHE APPENDIX

Not applicable. BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to access floor systems, and more particularly to access floor systems that use inexpensive, sub-floor support structures made of recycled plastics that are flame retardant and have a desired amount of elasticity and impact strength. Description of the Related Art

Office buildings with access floor systems, such as the access floor system disclosed in U.S. Patent No. 4,905,437, are very popular. Some important reasons for their popularity is that they can be easy to install, easily adaptable for different power and communication network configurations, and can be easily modified after installation if the tenant's needs change.

Access floor systems, such as the one disclosed in the '437 patent, include a plurality of interconnected support structures, called support modules that are laid out in a side- by-side manner to form a grid matrix over the floor's concrete slab as shown in FIG. 1. Each support module is of unitary construction and includes a central prop and three triangularly aligned side props. The central prop and side props are arranged in a square grid arrangement. Each side prop includes a hollow cylindrical body portion with a center boss.

Located laterally from the central prop on the side opposite the side props are three triangularly aligned prop pads. The prop pads are arranged in a square grid arrangement with the central prop and identical to the square grid arrangement made by the side props and the central prop. Each pad includes four upward extending clips designed to engage the center boss located on the side props on an adjacent support module. Each pad and the central prop includes holes that enable them to be securely attached to a concrete slab using suitable connectors.

Extending between the center prop and the side props and the pads are extension arms. The arms are semi-circular in cross-section with a flat bottom surface that are even or flush with the central prop, the side props and the pads thereby enabling the entire support module to rest evenly over the concrete slab.

In order to keep the costs of materials and installation as low as possible, the support modules used in access floor systems are typically made of polypropylene that can be injection molded. Recently, new building codes have been promulgated in many municipalities that require the support members used in access floor systems be made of flame retardant. Unfortunately, adding a flame retardant chemical to the polypropylene changes the support module's elastic and impact strength properties.

Also, many municipalities have promulgated rules that require the entire access floor system installed on a floor or space in a building be removed if it is no longer being used. With these new rules, it is anticipated that large quantities of recyclable plastics used to make support modules will soon be available and that the demand for support modules in an access floor system made of recyclable material will increase. What is needed is an improved support module designed for an access floor system that has good flame retardant properties, made of recyclable polypropylene, and has the desired elastic and impact properties necessary for an access floor system.

SUMMARY OF THE INVENTION

The above stated objects are met by the improved support structure for an access floor system disclosed herein made of recyclable polypropylene with a reinforcing filler and a fire retardant added thereto to produce a module with suitable impact strength with sufficient elastic and flame retardant properties. In the preferred embodiment, each module is made of recyclable polypropylene with a modulus of elasticity to approximately 87,000 MPa and an impact strength of approximately 7.5 ft.lb./in. To produce such a support module with a modulus of elasticity of approximately 130,000 MPa and a minimum impact strength of 1.9 ft.lb/in, a reinforcing inorganic mineral filler, approximately 5% by weight, such as talc or montmorillonite clay is added to the recycled polypropylene resin. This is contrary to the teaching in the prior art of compounding plastic material where it is generally believed that adding a mineral filler to polypropylene resin increases strength and stiffness, but reduces impact strength. Tests have shown that not only is the modules impacts strength and modulus of elasticity increased, but also one particular filler, montmorillonite clay, has fire retardant properties as well. Also disclosed herein is the use of an optional binding additive to the polypropylene and filler composition to improve the bonds between the polypropylene polymers and the filler. DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a floor support module found in the prior art. FIG. 2 is a table showing the ingredients used to make the concentrations used in the experiments shown in Table 3.

FIG. 3 is a table showing the experimental test results of a polypropylene polymer, the mineral inorganic filler and use of the optional binding additive.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An improved support module for an access floor system disclosed herein made of recyclable polypropylene with a reinforcing inorganic mineral filler to produce support modules with suitable impact strength and elastic properties and fire retardant properties for used.

In the preferred embodiment, each support structure has a shape and size similar to the support module shown in FIG. 1 and disclosed in U.S. Patent No. 4,905,437 and now incorporated by reference. It should be understood, however, that the use of recyclable polypropylene and a mineral filler could be used to manufacture other types of support structures and components used with access floor systems.

As stated above, it is important that support structure used with access floor systems have adequate modulus of elasticity and impact strength. Ideally, the support modules should have a modulus of elasticity of approximately 900 MPa and an impact strength of approximately 2.2 flt.lb./in.

In this invention, a recyclable polypropylene available as pellets is mixed with 45 to 50% (wt/wt) of a mineral filler, such as talc or montmorillonite clay. The purpose of the mineral filler is to increase the support module's impact strength and modulus of elasticity which is less that desired with recyclable polypropylene. Tests have also indicated that one particular type of mineral filler, montmorillonite clay, also provides flame retardant properties to the finished support structure. Tests have also shown that the adding or bonding chemicals to the polypropylene-filler composition can also increase the impact properties of the support structure. FIG. 3 shows a Table 3 that presents the results of twenty-two experiments conducted on twenty-two samples (Experiments 9-30) with two recyclable polypropylene products, two inorganic mineral filler products, and two additive products. The type of concentrate and additive is indicated in the Additive column. The make up of each composition of polypropylene resin, mineral filler, and additive shown is shown in Table 2 shown in FIG. 2. The two recyclable polypropylene products used were sold under the trademark LONE STAR 111 by Lone Star Chemicals, located in Grapeville, Texas), and the trademark PROFAX 6524.

These were two types of inorganic mineral filler used. The first four concentrates were made of 45 to 50% talc sold under the trademark NICRON 403 by Fitz Chem Corporation. The fifth and sixth concentrates were made of 50% montmorillonite clay sold under the trademark NANOCLAY.

Added to composition 2 was a polypropylene bonding additive (5%) sold under the trademark Fusabond by Dupont Canada, Inc. of Ontario, Canada. Added to compositions 3 and 4 was the bonding additive zinc sterate (3 and 5%, respectively).

In experiments 21 and 23, a nonoclay product was used that is sold under the trademark NanoMax by Amcol International Corporation, Arlington Heights, Illinois. The NanoMax product is made of 50% nanoclay.

All of the experiments were conducted using an Instron 4400 universal testing machine. In summary, the experiments clearly show that when 25 to 33% of talc or clay filler was added to 66% (wt/wt) of recyclable polypropylene resin, the mechanical properties of the finished product was favorably adjusted for use in an access floor system. The experiments also show that montmorillonite clay was especially beneficial. In compliance with the statute, the invention described herein has been described in language more or less specific as to structural features. It should be understood, however, that the invention is not limited to the specific features shown, since the means and construction shown is comprised only of the preferred embodiments for putting the invention into effect. The invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the amended claims, appropriately interpreted in accordance with the doctrine of equivalents.

Claims

1. A floor access support structure, comprising:

At least 66% (wt/wt) recyclable polypropylene, and; a 25 to 33% (wt/wt) reinforcing mineral filler; 2. The floor access support structure, as recited in Claim 1, wherein said mineral filler is talc.

3. The floor access support structure, as recited in Claim 1, wherein said mineral filler is montmorillonite clay.