2. Description of the Related Art For many years, manufacturers have produced matrix materials through corrugation, fluting, pleating and the like for use in packaging, construction, transportation, recreational, furniture, and aerospace industries. A primary purpose for the use of such matrix materials has been to reinforce the traditional kraft liner.

SUMMARY OF THE INVENTION It is an object of the present invention to provide composite structures having a matrix with superior structural strength to be used in the packaging, construction, transportation, recreational and aerospace industries which has improved properties relative to known composite structures.

It is a further object of the invention to provide composite structures having a matrix which is dimensionallv stable under compressive stress.

Yet a further object of the invention is to provide composite structures having a matrix which is gas and moisture permeable.

It is another object of the invention to provide shock absorbing composite structures having a matrix made of latex impregnated composite materials.

Still a further object of the invention is to provide composite structures having a matrix having a balance of stiffness and softness to provide good energy dissipation.

Yet another object of the invention is to provide composite structures having a matrix which is water-resistant and does not deteriorate, crack, or become brittle and harden after being wetted.

A further object of the invention is to provide composite structures having a matrix for use in those applications where resistance to mold, mildew and fungi are required.

It is another object of the invention to provide composite structures having a matrix which is light and heat resistant, and which acts as an insulator to prevent transmission of heat.

An additional object of the invention is to provide composite structures having a

matrix which is easily secured in position between solid and flexible surfaces.

An even further object of the invention is to provide composite structures having a matrix made from renewable, recyclable, and/or recycled components, utilizing post-consumer waste.

An additional object of the invention is to provide composite structures having a matrix which may be combined with all known adhesive systems including, but not be limited to, water-based, synthetic or natural latex, as well as 100% solids hot melt systems.

It is still a further object of the invention to provide composite structures having a matrix that may be produced with natural and synthetic fibers that may be used for electrostatic dissipative and/or conductive requirements.

In accordance with the foregoing objects, the invention relates to composite structures or products for use in the packaging, construction, transportation, recreational, furniture and aerospace industries which have improved durability and are lighter than conventional products.

The invention provides composite structures or products for the manufacture of boxes, cartons, containers, or lids and for use in the construction, transportation, recreational, furniture, and aerospace industries. In certain applications, the matrix may be used as a sound absorber or reinforcing matrix in hollow core doors, or as a reinforcement of fiberglass boat hulls, shower stalls, and bathtubs.

The products are made of a composite matrix material having a substantially continuous web portion impregnated with a binder composition. The web portion of the composite material is made of a particulate, matrix forming material, preferably a natural or synthetic fibrous material. The binder composition binds the particulate, matrix forming material in the web and imparts resiliency and water resistance to the composite material. Preferably, the binder composition is a natural or synthetic rubber latex.

The single face or double faced corrugated, fluted, pleated or the like matrix material has superior physical strength as related to ring crush, edge crush and puncture resistance as well as improved dimensional stability.

The corrugated, fluted, pleated or the like impregnated fiber matrix may be resaturated. The invention provides products which exhibit superior dimensional stability, maintain a proper balance of rigidity and flexibility during their useful lives and are resistant to cracking and embrittlement, which contribute to durability.

The composite material for the matrix may be made by methods based on paper making processes, including, but not limited to, wet web impregnation, dry web impregnation, latex beater deposition, and continuous latex wet-end deposition. The impregnated matrix materials may

be produced in gauges ranging from 0.005 to. 126" in single ply or laminated form. The impregnated matrix material may be produced in electrostatic dissipative (ESD) as well as conductive form. The impregnated matrix materials may be treated, for example, to resist mold and mildew.

The composite matrix material is produced in the form of sheets or rolls, and the matrix material can be corrugated, fluted, pleated or the like from roll or sheet form. The composite matrix material can be fixedly secured, by mechanical and/or chemical methods, to a liner (s) or facer (s) to create composite structures or products of either single faced or double faced construction.

The composite structures or products may be combined with other products, single faced or double faced, and may be combined with other lesser quality composites.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a cross-sectional view of at least one first layer of a composite material having a substantially continuous web portion and a plurality of alternating ridges and grooves, and at least one second layer, more specifically two second layers, attached to the first layer in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawing, there is shown a composite structure in accordance with the invention.

The FIGURE shows a double faced composite structure 10 having a matrix or medium layer 12 formed from a composite material and top and bottom liners, facers or layers 14 and 16, respectively.

According to the invention, the composite structure or combination is made of a composite material having a substantially continuous web portion impregnated with a binder composition. The composite material is a matted, felted, non-woven sheet containing a web portion optionally with web portion additives, and a binder composition optionally with binder additives.

The web portion and web portion additives preferably comprise from about 50% to about 90% by weight of the dry weight of the composite material, and more preferably comprise from about 65% to about 75% by weight of the dry weight of the composite material. The binder composition and binder additives preferably comprise from about 10% to about 50% by weight of the dry weight of the composite material, and more preferably comprise from about 25% to about 35% by weight of the dry weight of the composite material.

The web portion of the composite material includes at least one particulate, matrix- forming component. Examples of suitable particulate, matrix-forming materials include: natural fibers including cellulosic fibers derived from a single source or a plurality of sources such as wood pulp, rags and cotton linters, and other cotton and vegetable fibers such as flax, hemp, abaca, jute, straw, ramie, sisal, istle, china grass, cotton grass, agave, pita, esparto, eucalyptus, evergreen and coniferous wood fibers, deciduous and broad-leaf hardwood fibers, comminuted and macerated waste fibers, viscose fibers, regenerated cellulose or cuprammonium type fibers, and rayon; synthetic fibers including polyolefins such as polyethylene, polypropylene and polybutylene, polyesters, nylons, acrylics, acetates, polyacrylonitriles, polycarbonates, triacetates, nytril, spandex, vinal and vinyon; wool fibers; glass fibers; mineral fibers; leather fibers; carbon fibers; ground cork; ground rubber; and mixtures thereof. Of these matrix-forming materials, natural fibers and/or synthetic fibers are preferred, with natural fibers being the more preferred. An especially preferred matrix- forming material is cellulosic fibers from one or more sources.

Preferably, the particulate matrix-forming component is a fibrous material having a denier of about 0.2 microns to about 40 microns and a fiber length of about 0.1 millimeter to about 20 millimeters.

The binder composition is a material capable of binding the particulate matrix- forming component in the web and preferably includes at least one natural or synthetic rubber latex.

Examples of suitable synthetic rubber latices include resins such as styrene-butadiene, carboxylated styrene-butadiene, polyacrylic ester, polymethacrylic ester, copolymers of acrylic ester and methacrylic ester, acrylonitrile-acrylic ester copolymer, polyvinyl acetate, polyisobutylene, a copolymer of vinyl acetate and acrylic ester, polychloroprene, acrylonitrilebutadiene, carboxylated acrylonitrile butadiene, polyurethanes, a copolymer of ethylene and vinyl acetate, acrylonitrile butadiene styrene, polyvinylidene (di) chloride, carboxylated butadiene styrene vinylidene chloride terpolymers, polyisoprene (natural and synthetic) and other elastomeric co-, ter-, and multi- polymers. The binder composition may include a single natural or synthetic rubber latex or a mixture of two or more such rubber latices. An especially preferred binder composition comprises styrene-butadiene.

The binder composition imparts water resistance to the composite material, while maintaining the other desirable properties of the web portion of the composite material.

As noted above, both the web portion and the binder composition optionally contain additives. These additives function as processing additives and/or end product additives to achieve certain desired results during the manufacture of the composite material and/or to impart certain desired characteristics to the combination. Additives are classified as"web portion"additives and

"binder"additives based on which component, the web forming component or the binder composition, the additive is initially mixed with. Thus, the same types of additives can be both web portion additives and binder additives.

The additives useful in the composite material are conventional additives, which are used for their known properties in preparing the composite material of the invention. Examples of suitable web portion additives include antifungal agents, antimildew agents, antibacterial agents, dyes, pigments, dispersants, wet strength aids, web processing aids, defoamers and sizing agents.

Examples of suitable binder additives include: surfactants, antioxidants, lubricants, crosslinking agents, catalysts, anti-ozonates, emulsifiers, wetting agents, colloidal stablilizing agents, vulcanizing agents, sizing agents, and defoamers.

The total amount of additives, both web portion and binder additives, in the composite material is preferably between about 0.5% and about 5.0% by weight based on the dry weight of the composite material.

Preferably, for use as a single ply or laminated material, the composite material has a thickness of between about 0.005 inch and 0.126 inch, more typically between about 0.015 and 0.026 inch.

The phrase"plurality of alternating ridges and grooves"as used herein is to be construed as including corrugated, fluted, pleated, scored and honeycomb structures which are per se well known in the art.

Composite materials for use in this invention can be made by modified paper-making processes wherein an aqueous slurry of the matrix-forming component and optionally the web portion additives is formed and then the slurry or a web formed from the slurry is impregnated with the binder composition and optionally the binder additives. The following modified paper-making processes in particular can be used to make the composite material for the combination of this invention: wet web impregnation; dry web impregnation; latex beater deposition and continuous latex-wet-end deposition. Each of the processes will be described briefly below. Detailed examples of these types of processes can be found in U. S. Patent No. 4,245,689.

In the following discussion, the term"fibrous"is to be construed as including particulate matrix-forming materials which are not technically fibers. However, since the basic processes discussed herein are modified paper making processes, which do involve primarily cellulosic fibers as the web or matrix-fonning component, the conventional term"fibrous"will be used.

In the wet web impregnation method, the fibrous matrix-forming component (s) and web portion additive are dispersed in water to prepare a slurry stock and the slurry stock passes

through a refiner or beater which cuts the fibers and ruptures the surfaces of the fibers to improve their bondability. The refined slurry stock is fed to a sheet former of conventional construction. On the sheet former, a fibrous web is formed by removal of water from the approximately 99% by weight water content of the refined slurry stock feed to a fibrous web having about 72% by weight water. Following formation of the continuous fibrous web on the sheet former, it passes to a press section which removes water from the web to reduce the water content to about 50% to 60% by weight. The pressed web then passes to a saturator which introduces the binder composition and binder additives into the fibrous web. Excess binder composition and binder additives are removed from the fibrous web and then the binder impregnated fibrous web passes to dryers which dry the impregnated web to a moisture content less than about 3% by weight. Subsequent conventional steps such as printing, coating, calendaring, laminating and the like can then be performed as desired.

The dry web impregnation is similar to the wet web impregnation method, with the exception that the fibrous web proceeds directly to the dryers from the press section to produce a dry, non-impregnated fibrous web. The fibrous web is subsequently impregnated with the binder composition and binder additives, in a separate production process, by passing the dry fibrous web through a bath of the binder composition and binder additives, removing excess binder composition and binder additives, and then drying the impregnated web to a moisture content less than about 3% by weight.

In the latex beater deposition method, the binder composition and binder additives are mixed with the refined slurry stock in a latex deposition chest before the slurry stock is fed to the sheet former. A deposition agent or combination of agents is added to the latex deposition chest as well, to break the binder latex composition and deposit binder particies uniformiy on the fibers.

The binder composition and binder additives are mixed with the refined fiber slurry stock in a batchwise manner. The binder-containing slurry is then fed to the sheet former, press section, and dryers to produce the composite material. There is no additional binder composition deposited on the web after sheet forming in this process.

The continuous latex wet-end deposition method differs from the latex beater deposition method in that the binder composition and binder additives are introduced into the slurry stock, before the sheet former, continuously rather than in a batchwise manner. In this continuous method, all binder composition and binder additives are added to the slurry stock before the slurry is formed into a web by the sheet former, for example, at the inlet to a fan pump or in the headbox of the sheet former.

The above methods are examples of methods for making the composite material for

the composite structure or combination of the invention, but should not be construed as the only suitable methods. The composite material made by the above methods is in the form of large, continuous sheets which can be cut and stacked or can be rolled around a supporting core.

To make the composite structure or combination according to the invention, the composite material is corrugated, fluted, pleated or the like and combined with one or more facers or liners or incorporated into other structures using conventional techniques and equipment well known in the art. The facers or liners or other layers of the composite structures or products may be made of any conventional material including a substantially continuous web as described herein either impregnated or not impregnated with a binder composition.

To further illustrate the invention, an elastomeric matrix material is specifically designed for use as reinforcement in composite sandwich constructions. The matrix material is fluted or corrugated or the like to produce a matrix with a high strength-to-weight ratio. The wet web saturation process, for example, is used to produce a material which is fluted, for example, to the maximum potential with maximum resistance to crushing of the flutes. The matrix material offers dry and wet dimensional stability and is thermoplastic for molding or fluting or the like. It is water-resistant and contains excellent physical properties even when wet. The matrix may be treated to be resistant to the growth and harmful action of bacteria, fungi and mold. The products are preferably made from cellulose fibers which are formed into a web that is then saturated in a latex bath. The latex impregnates the fibers and coats each fiber within the web. In curing and drying, this web is chemically bonded to give a product which has high internal and overall strength, good dimensional stability and excellent aging properties. The nature of this type of manufacturing process creates products with unique orientation. The fibers that make up the web are aligned in such a manner that articles cut from them are extremely flexible in the cross machine direction, yet firm in the machine direction. The products will not harden, crack or buckle.

A typical composite structure is a matrix material web as described above in corrugated form having a gauge of. 018" combined with a kraft liner or sheet having a gauge of . 009" to form a single faced product. Another typical composite structure is a matrix material web as described above in corrugated form having a gauge of. 018" combined with a matrix material as described above in sheet form having a gauge of. 018" to form a single face product.

The invention has been described with reference to preferred embodiments and specific examples thereof which are considered illustrative only of the principes of the invention.

Since numerous changes and modifications will readily occur to those skilled in the art, it is not desired to limit the invention to the exact embodiments shown and described, and suitable modifications may be made without departing from the scope of the invention as described above and as defined in the appended claims.