Road structure – process – or apparatus – Pavement – Rubber or rubber-like
Reexamination Certificate
2002-06-24
2004-03-09
Pezzuto, Robert E. (Department: 3671)
Road structure, process, or apparatus
Pavement
Rubber or rubber-like
C404S044000, C404S082000
Reexamination Certificate
active
06702514
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a paving material for footways, which is superior in strength, lightweight property and water permeability, and a method of producing the same.
2. Description of Related Art
As a conventional paving material for footways, there have been known (1) a paving material for footways comprising two layers wherein the upper layer is obtained by binding rubber chips with a urethane resin binder, and the lower layer is obtained by binding gravel with a binder (Japanese Utility Model Application, First Publication No. Hei 6-4105), (2) a paving material for footways comprising three layers wherein the upper layer is obtained by binding only rubber chips with a binder, the intermediate layer is obtained by binding a mixture of rubber chips and gravel with a binder, and the lower layer is obtained by binding rubber chips with a binder (Japanese Unexamined Patent Application, First Publication No. 2000-204508), (3) a paving material for footways obtained by binding a mixture of gravel and rubber chips with a urethane resin binder (Japanese Unexamined Patent Application, First Publication No. 2001-270772), and (4) a paving material for footways obtained by binding a mixture of rubber chips and crushed fragments of artificial marble with a binder (Japanese Unexamined Patent Application, First Publication No. Hei 11-117219). These paving materials for footways have not been satisfactory paving materials for footways because while they are superior in elasticity, they are insufficient in one of strength, lightweight property or water permeability.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a paving material for footways, which is superior in strength and lightweight property.
Another object of the present invention is to provide a paving material for footways, which is superior in strength, lightweight property, water permeability and walkability.
Still another object of the present invention is to provide a paving material for footways, which reuses waste FRP molded article and is superior in strength, lightweight property, water permeability and walkability.
The present invention provides a paving material for footways, comprising an upper layer and a lower layer, wherein the upper layer is made of rubber chips (A
1
) and a synthetic resin (A
2
) for binding the rubber chips (A
1
), and the lower layer is made of a fiber-reinforced plastic (B).
Also, the present invention provides a method of producing a paving material for footways, comprising a first step of charging a mixture of rubber chips (A
1
) for forming an upper layer and a synthetic resin (A
2
) for binding the rubber chips (A
1
) into a mold; a second step of charging a mixture of crushed fragments (B
1
) of a fiber-reinforced plastic, for forming a lower layer, and a thermosetting resin (B
2
) into the mold; and a third step of pressing the mold under heating, thereby integrally molding the mixtures.
Furthermore, the present invention provides a method of producing a paving material for footways, comprising a first step of laying a mixture of crushed fragments (B
1
) of a fiber-reinforced plastic, for forming a lower layer, and a thermosetting resin (B
2
) on a base to be paved; a second step of laying a mixture of rubber chips (A
1
), for forming an upper layer and a synthetic resin (A
2
) for binding the rubber chips (A
1
) thereon; and a third step of integrating and curing the mixtures.
The paving material for footways of the present invention is superior in strength, lightweight property, durability and water permeability and can also utilize waste rubber and waste FRP.
According to the present invention, it is possible to employ a waste rubber and a thermosetting resin waste, which have been exclusively subjected to landfill disposal, in the paving material for footways. Furthermore, since the paving material for footways can be cut by a woodworking saw without using a cutter for stone material and also can be easily cut to match odd-shaped floors or roadsides even when the odd-shaped road is paved with blocks, laying can be easily carried out and the effect of reducing the laying time can be achieved. After use, the paving material for footways of the present invention can be utilized as it is as a raw material and fuel for cement after incineration, and is suitable for a recycling society.
DETAILED DESCRIPTION OF THE INVENTION
The rubber chips (A
1
) used in the upper layer are in the form of chips obtained by cutting a rubber material made from components such as natural rubber, polyisoprene rubber, styrene rubber, butadiene rubber, chloroprene rubber, butyl rubber, nitrile rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), chlorosulfonated polyethylene, urethane rubber, acrylic rubber or polysulfide rubber, and is preferably crushed fragments of waste rubber made of these components or crushed fragments of rubber products such as used tires or tubes.
The rubber chips (A
1
) are produced by crushing the rubber product using a publicly known and conventional machine and are preferably in the form of fibers or granules, and the average particle diameter is preferably within a range of from 0.5 to 20 mm, and more preferably from 1 to 10 mm. These rubber chips are used alone or in combination.
The synthetic resin (A
2
) used in the upper layer may be a synthetic resin capable of binding the rubber chips (A
1
). Examples of the synthetic resin include polyurethane resin, epoxy resin, vinyl ester resin, and unsaturated polyester resin. Preferably, the synthetic resin is a polyurethane resin. The polyurethane resin used herein is preferably in the form of liquid at normal temperature and is a terminal NCO group-containing urethane prepolymer, which is preferably prepared by reacting publicly known polyols with an organic isocyanate compound at an equivalent ratio NCO/OH of 1.5 or more, and more preferably from 1.5 to 2.0, and the polyurethane resin is a one-pack type resin made of these polyurethane polymers or a mixture thereof, or a two-pack type resin prepared by mixing the urethane polymer with the polyol. The organic isocyanate compound is a compound selected from aromatic diisocyanates and aliphatic diisocyanates such as 2,4-tolylene diisocyanate (abbreviated to TDI), 65/35-TDI, 80/20-TDI, 4,4′-diphenylmethane diisocyanate (abbreviated to MDI), dianisidine diisocyanate, tolylene diisocyanate, methaxylene diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, 1,5-naphthalene diisocyanate, polymethylenepolyphenyl polyisocyanate, hydrogenated MDI, and hydrogenated TDI alone or a mixture thereof.
The upper layer is composed of the rubber chips (A
1
) and the synthetic resin (A
2
), but it is preferred to mix in hard granules (A
3
) in order to prevent sliding and to control the elasticity.
Specific examples of the hard granules (A
3
) include the crushed fragments of thermosetting resin molded articles, the crushed fragments of fiber-reinforced plastics of thermosetting resins, and inorganic substances (e.g. aggregate such as sand, stone or mineral, or filler such a calcium carbonate). Specific examples of the thermosetting resin used in the crushed fragments of the thermosetting resin molded articles include unsaturated polyester resin, vinyl ester resin, phenol resin, melamine resin, epoxy resin, and acrylic resin. The crushed fragments of fiber-reinforced plastics are preferred. As used herein, the term “fiber-reinforced plastic” refers to a molded article (hereinafter referred to as an FRP molded article) produced by mixing a radical-curable unsaturated resin such as unsaturated polyester resin, vinyl ester resin, or crosslinkable acrylic resin (acrylic syrup) with a glass fiber reinforcing material and curing the mixture. An unsaturated polyester resin glass fiber-reinforced molded article is particularly preferred. Although the crushed fragments of the waste of the FRP molded article are preferred as the hard granules (A
3
), not only the recovery material
Itoh Tetsuo
Kaneko Masaichi
Mahira Koichi
Armstrong Kratz Quintos Hanson & Brooks, LLP
Dainippon Ink and Chemicals Inc.
Mayo Tara L.
Pezzuto Robert E.
LandOfFree
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