FULLY INTEGRATED METHOD FOR PRODUCING ABSORBENT PRODUCTS
BACKGROUND OF INVENTION Absorbent products, such as baby diapers have a 90 to 95% market penetration in the United
States and Europe. The levels of market penetration in some of the emerging market countries such as China and India are less than 5 %. Part of the reason for this low level of penetration is the relative high cost of these products in those markets.
Manufacturers of absorbent products in the emerging market countries face an enormous challenge in trying to find ways to produce lower cost products. The cost of raw materials comprise up to seventy to eighty percent of the cost to manufacture such products. In order to produce a functional absorbent product a minimum amount of conventional materials need to be employed. If a manufacturer reduces the amount of material used beyond this minimum, the functionality of the product is greatly diminished. Absorbent products such as baby diapers, feminine hygiene pads and adult incontinent products are typically constructed of several different types of materials. These products typically consist of a permeable non-woven top sheet, an impermeable back sheet and an absorbent core sandwiched there between. The absorbent core typically consists of wood fluff and a water- absorbing polymer, which is prepared from monomers of acrylic acid. One of the costs of manufacturing absorbent products is the waste that is produced. Given that 70% to 80% of the product costs are associated with the materials used, any waste produced can be costly to a business. Typically, a conventional manufacturing process produces 5 to 10% waste due to leg cut outs, left over material and culled products (products that are irregular or damaged). This percentage of waste can be even higher for older absorbent product producing machines that are typically in use in the developing world.
Accordingly, there is a need in the art for novel approaches to recycle waste that is generated during the production of absorbent products. SUMMARY OF INVENTION
The present invention provides an absorbent product, such as disposable diapers, incontinent pads, sanitary napkins that has an absorbent core that comprises recycled synthetic material. The core is produced from the waste created in the manufacturing process of previously produced absorbent products.
In accordance with another aspect the present invention comprises a method of producing absorbent products, including the steps of capturing the waste consisting of "compatible" components, shredding the waste, pelletising the waste and melting and extruding the "compatible" waste into synthetic core fiber for use in new absorbent products.
In accordance with another aspect the present invention comprises a method of producing absorbent products, including the steps of capturing the waste consisting of "compatible" and
"incompatible" components, shredding the waste, separating the waste into compatible and incompatible components, turning the compatible waste into pellets and melting and extruding the "compatible" waste into synthetic core fiber for use in new absorbent products.
The above and other aspects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 illustrates a top view of a conventional diaper showing the absorbent synthetic core and leg cut outs that consist of compatible material.
Figure 2 illustrates the manufacturing steps for the manufacture of an absorbent garment with an absorbent core with recycled synthetic fibers.
DETAILED DESCRIPTION OF INVENTION
The invention relates to the recycling of absorbent garment manufacture waste materials into continuous synthetic core fibers which are used to produce new absorbent cores. The types of absorbent products that can be produced include disposable diapers, incontinent pads, sanitary napkins wherein the absorbent core comprises recycled synthetic materials.
FIGURE 1 is a plan view of a conventional diaper Ln its uncontracted state with the center oval area showing the absorbent core 10 and diaper chassis 20 leg cut out 30 which consists of compatible material. Typical diaper construction consists of a liquid pervious top sheet, a liquid impermeable back sheet and an absorbent core sandwiched there between. It is understood that a variety of absorbent garment constructions know in the art could incorporate the absorbent core of the present invention.
FIGURE 2 shows the manufacturing steps involved in collecting, sorting (for waste that contains both compatible and incompatible material), shredding, forming pellets, melting and extruding to produce recycled continuous synthetic fiber. Said fiber can then be used in manufacturing new absorbent cores.
Conventional methods for shredding, forming pellets, melting and extruding can be used. Such methods are disclosed in US Patent Nos. 3,081,519, 3,165,563, 3,242,035 and 4,054,550, which are incorporated herein in a manner consistent with the present invention. It is important to note that when separating incompatible material from compatible material, the percentage of incompatible material needs to be very low. Otherwise, the spinneret could become clogged due to contaminates (incompatible material).
The "top sheet" of the present invention can be any permeable polymeric plastic non-woven sheet known in the state of the art. A suitable top sheet may be made from apertured plastic films, polyolefin fibers (e.g. polyethylene or polypropylene fibers) or combinations thereof. It is understood that additional layers may be present between the absorbent core and the top sheet. In additional it is understood that such back sheet needs to be a "compatible" material.
The "absorbent core" can be any synthetic material known in the state of the art that can be made into tow and recycled. Such materials include synthetic materials such as polyolefins. Polyolefins include polypropylene and polyethylene. Polypropylene is preferred because it has been shown that polypropylene undergoes no significant change in mass and alterations to the polymer chains after repeated extrusion. The application properties of the material are almost unaffected nor degraded. The absorbent core of the present invention may also include a "wrap" that encases the synthetic fiber core and super absorbent particulate. Preferably the wrap should be a polypropylene non-woven material for purposes of recycling.
In addition, the absorbent core of the present invention may include a transfer or acquisition layer interposed between the absorbent core (or wrap if used) and the top sheet. It is preferred that the transfer layer be made of polypropylene as well for purposes of recycling.
The super absorbent particulate of the present invention can be any conventional water- swellable material such as synthetic hydrogel polymer. These include polyacrylic acids.
The "back sheet" of the present invention can be any impermeable polymeric plastic and/or non-woven sheet known in the state of the art. A suitable back sheet may be made from films polyethylene and polypropylene and blends of these materials. It is understood that additional layers may be present between the absorbent core and the back sheet. In additional it is understood that such back sheet needs to a "compatible' material.
For purposes of this patent application, "waste" refers to all material that contains some level of "compatible" material as defined herein. "Compatible" material refers to all material that can be recycled into new continuous synthetic fibers (tow) that can then be used to produce a matrix for absorbent cores. Compatible material includes non- woven leg cut out material, bag trim, left over material from stub rolls and shrink wrap. The expectation is that this compatible material will have a melt point lower than virgin resin. "Virgin resin" meaning start source material that has not be made into any product.
"Incompatible" material includes all material that cannot be recycled into new continuous synthetic fibers. Such material includes super absorbent particulate, box corrugate and other cellulose material.
It is understood that there will be waste that will contain both compatible and incompatible material that would need to be separated. Such waste includes culled diapers and super absorbent particulate bags. It is further believed that other sources of compatible material could be used such as recycled plastic bottles. It is understood that the reclaimed compatible material can be combined with virgin resin to produce the synthetic core fiber. Special note needs to be made to make certain that there is a consistency in the percentage of reclaim and virgin resin combined. While particular embodiments and/or individual features of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Further, it should be apparent that all combinations of such embodiments and features are possible and can result in preferred executions of the invention. Therefore, the appended claims are intended to cover all such changes and modifications that are within the scope of the invention.