US3773613A

US3773613A - Method for converting plastic-containing broke to fluff

Info

Publication number: US3773613A
Application number: US00188871A
Authority: US
Inventors: C Lee; F Granberg
Original assignee: International Paper Co
Current assignee: International Paper Co
Priority date: 1971-10-13
Filing date: 1971-10-13
Publication date: 1973-11-20
Anticipated expiration: 1990-11-20
Also published as: CA978407A

Abstract

A method for converting plastic-containing, particularly filament-reinforced, cellulosic broke to a fluff of substantially separated fibers and pieces of plastic in the substantial absence of water. The dry broke material is first subjected to a pretreatment step in the absence of liquid wherein the broke pieces are rubbed against one another to free about 50 percent of the cellulosic matter as individual fibers and reduce the plastic matter to pieces having lengths of generally less than about one and one-half inches. The pretreated broke is then conveyed via storage and cyclone separator steps to a refiner treatment wherein the dry broke material is refined into a fluff containing dry cellulosic fibers and randomly distributed plastic pieces. The fluff contains less than 30 percent by weight plastic pieces obtained as a result of adding dry cellulosic pulp to the broke prior to the refining step or prior to the pretreatment step.

Description

United States Patent 1 Lee et al.

[54] METHOD FOR CONVERTING PLASTIC-CONTAINING BROKE TO FLUFF [75] Inventors: Charles A. Lee; Frederick M.

Granberg, both of Knoxville, Tenn.

[73] Assignee: International Paper Company, New

York, NY.

[22] Filed: Oct. 13, 1971 [21] Appl. N0.: 188,871

[52] U.S. Cl 162/191,161/158,161/176, 162/4, 162/100, 162/264, 241/19, 241/23,

[51] Int. Cl. D21f l/66, D21b 1/08, B271 11/08 [58] Field of Search, 162/4, 147, 191, 162/55, 28, 264, 146, 261, 13, 100, 183;

[451 Nov. 20, 1973 8/1971 Blomgvist et al. 241/28 6/1972 Price 264/115 X [5 7] ABSTRACT A method for converting plastic-containing, particularly filament-reinforced, cellulosic broke to a fluff of substantially separated fibers and pieces of plastic in the substantial absence of water. The dry broke material is first subjected to a pretreatment step in the absence of liquid wherein the broke pieces are rubbed against one another to free about 50 percent of the cellulosic matter as individual fibers and reduce the plastic matter to pieces having lengths of generally less than about one and one-half inches. The pretreated broke is then conveyed via storage and cyclone separator steps to a refiner treatment wherein the dry [56] References cued broke material is refined into a fluff containing dry UNITED STATES PATENTS cellulosic fibers and randomly distributed plastic 3,556,934 l/1971 Meyer 162/ 169 pieces The fluff contains less than 30 percent by 3,325,345 6/1967 Hider 162/16 weight plastic pieces obtained as a result of adding dry a z g i g cellulosic pulp to the broke prior to the refining step e a e 3,245,868 4/1966 Espenmiller et a1... 162/191 x pnor to the pretreatment Step 3,356,016 12/1967 Eidal 241/ 196 X 9 Claims, 3 Drawing Figures DRY PLASTlC- CONTAlNlNG BRO K E 10 REDUCER 34 DRY PULP 3o STORAGE FLOW Bummer;

AIR 3B REFINER 50 PRODUCTION Patented Nov. 20, 1973 5 Sheets-Sheet 1 DRY PLASTIC- CONTAINING AIR BROKE IO REDUCER ,34

DRY PULP STORAGE I FLOW DIVERTER s2 54 Fig.1 48

W251 Cm REFINER 50 a: PRODUCTION LINE INVENTORS.

Charles A. Lee Frederick MGranberg Patented Nov. 20, 1973 3,773,613

3 Sheets-Sheet 2 -IlHI 'INVENTORS. Charles A. Lee

Frederick M. Granberg METHOD FOR CONVERTING PLASTIC-CONTAINING BROKE TO FLUFF This invention relates to the conversion of plasticcontaining broke to a useful absorbent product.

Tissue webs reinforced with a plurality of continuous plastic filaments to develop increased strength in the webs, are being used in an increasingly large number of disposable products. The low cost, absorptive qualities, and other characteristics of these webs make them particularly useful for such products as disposable diapers, surgical wipes, towels and disposable clothing.

in the usual reinforced tissue web, the filaments usually comprise a synthetic resin, such as nylon or polyester but other filaments may also be employed in products for which a specific property is desired. Not infrequently, these filaments are bonded to the tissue web as by a synthetic resin adhesive.

in the course of manufacturing the filamentreinforced tissue webs and in producing products incorporating such reinforced webs, it is not uncommon for about ten or more percent of the raw material to be lostin the form of broke. Such broke has a substantial value to the manufacturer if it is reusable in the manufacturing process. Absent such reusability, the broke is substantially valueless in the market and in fact represents a disposal problem for the manufacturer.

Dry refining of pulp (free of plastic) comprising the steps of chopping the pulp and comminuting it in a dry refiner has been practiced in the prior art. Commonly, a refiner, such as a double disc refiner, is adjusted so that those portions thereof which act upon the pulp to separate the fibers into individual fibers and/or small bundles of fibers are spaced apart by a very short distance such as several thousandths of an inch. The action of the refiner upon the fibrous pulp is severe and large amounts of work are done upon the material causing its temperature to rise considerably. Much of the broke which contains plastic is incompatible with such prior art dry refining in that the plastic filaments become entangled in the refiner and clog it, causing the action of the refiner on the plastic-containing broke to generate sufficiently high temperatures as cause scorching of the cellulosic fibers which both weakens the fibers and makes them unsightly. In addition, the heat generated in the refiner softens the plastic which, while it is soft and being subjected to the refining action, picks up fibers and filaments to form unmanageable agglomerations of fibers and plastic. This latter problem is particularly serious when the plastic material in the broke possesses a low softening temperature. Polyethylene, frequently in sheet form, is found in some types of broke such as the broke generated in the manufacture of disposable diapers where thin polyeth ylene sheet often is employed as a barrier against liquid flow through the thickness of the diaper. This plastic softens at about 180 Fahrenheit and broke containing this plastic is not successfully processed'in accordance with the prior art methods because of the tendency of the plastic to soften and clog the apparatus, form clumps of plastic, or form agglomerates of plastic and cellulose fibers.

Among other things, conversion of the broke in the dry state offers the advantages of direct reuse of the broke in an existing process for manufacture of a product such as a disposable diaper, sanitary napkin or the like where the converted material is desirably dry when incorporated into the product.

It is therefore an object of the present invention to provide a method for converting plastic-containing broke, especially filament-reinforced broke, to absorbent matter useful in the production of an absorbent product. It is also an object to provide a method for converting plastic-containing broke to a useful product in the substantial absence of a liquid. It is also an object to provide a novel fluff product. Other objects and advantages will be recognized from the following description including the drawings in which:

FIG. 1 is a schematic of a system embodying the steps of the disclosed method;

FIG. 2 is a representation of apparatus suitable for preliminarily treating broke in accordance with the invention; and

FIG. 3 is a fragmentary top view of the apparatus of FIG. 2 with a portion of the housing omitted.

As disclosed herein, dry plastic-containing cellulosic broke, frequently including filament-reinforced cellulosic broke, is converted to substantially separated fibers and small pieces of plastic in the substantial absence of water to produce an absorbent material, at times referred to as fluff. In the disclosed method, dry plastic-containing broke of various dimensions is subjected to a preliminary treatment wherein the broke is reduced to relatively small pieces and worked to the extent that about percent of the cellulose fibers are separated into individual fibers and small bundles of fibers. The action upon the fibers also separates many of them from the plastic, especially in the instance where the broke includes plastic filaments bonded to a cellulose sheet. During pretreatment, the plastic matter in the broke is reduced to broken pieces and lengths of generally less than about one and one-half inches in their major dimension. The preliminarily-treated material is thereafter further refined in the dry state, the broke having added thereto, prior to this refining step, a diluting quantity of dry pulp sufficient to reduce the plastic content of the material to less than about 30 percent by weight. An improved absorbent product, e.g. fluff, is obtained.

By way of illustration, the broke referred to herein comprises cellulosic matter, usually in sheetform, reinforced with plastic filaments. Frequently, the cellulosic sheet will be tissue paper having a basis weight of about 16 pounds per ream or less. The filaments at times are bonded to the cellulosic sheet by means of a plastic adhesive. The broke also may include plastic sheet material, such as a thin sheet of polyethylene (e.g., less than about 0.001 inch thick) or the like at times used as a liquid flow control element in disposable absorbent products, e.g. disposable sanitary napkins or diapers. It will be recognized, however, that other types of plasticcontaining broke are convertible to a fluff or similar useful product employing the method disclosed herein.

As illustrated in the figures, dry plastic-containing broke is pretreated in a material reducer 10 to which the broke is admitted in bulk, bale, bundle or other suitable form. In the illustrated method, dry cellulosic pulp is admitted to the reducer simultaneously with the broke and in a proportion sufficient to dilute the broke by reducing the weight percentage of plastic matter in the broke as will be referred to hereinafter. It will be recognized that in the art dry paper or pulp includes about 6-10 percent by weight of moisture and the term is so used in the present disclosure. Fluff, as the term is used herein, comprises a fibrous material which has been difibrated to the extent that it contains relatively few broken fibers and only a minor portion of fiber bundles. The term is also used to denote a defibrated fibrous material as above and which includes a further material such as small pieces of plastic.

During pretreatment in the reducer the action upon the pulp and the plastic-containing material of the present disclosure includes a reduction of the material so that the major portion of it is less than a preselected size. Initially the bulk material is reduced to that size which will permit further processing through the preliminary treatment. Thus, larger pieces are initially formed but these are further reduced in size as the pretreatment progresses so that eventually substantially all the pieces have a major dimension of less than about one and one-half inches and are suitable for refining.

In addition to the initial break-up of the material, during pretreatment, it is caused to accumulate in a layer or layers between opposed working surfaces at least one of which is movable with respect to the other. While so layered, the material is worked upon itself with a substantial portion of the reducing action being accomplished by action of the broke itself. The action of the broke upon itself while layered between opposed working surfaces may be visualized as similar to bydraulic shear wherein two spaced apart working surfaces which move relative to one another set up shear forces in the liquid between the surfaces. Thus in the present process the faces of the body of pulp are worked by moving work surfaces so that pieces of pulp are moved relative to one another and the pieces themselves rub and shear pieces and fibers from one another. This action is to be distinguished from a grinding and tearing action which tends to break individual fibers and form substantial quantities of fines. The working of applicants method frees substantial quantities of individual cellulose fibers and small bundles of fibers and reduces the plastic matter to small pieces so as to reduce the work necessary in a subsequent refining step to accomplish relatively complete difibration of the broke to a fluff. The pieces of plastic are dispersed in the broke and being harder and more abrasive than the cellulose fibers, enhance the reducing action in the layered material. In a preferred pretreatment of the broke, ofthe order of at least 50 percent of the cellulose fibers are separated into individual fibers and/or small bundles of fibers. Sheet plastic in the broke is reduced to pieces generally less than about one and one-half inches in their major dimension and plastic filaments are broken into lengths of less than about 1% inches.

7 Many pieces of sheet plastic and many lengths of filaments are much smaller. Pretreating the broke to bring about greater reduction in the size of the pieces or more extensive defibration has been found unnecessary for successful subsequent refining, hence wasteful. Substantially less pretreatment, however, fails to provide a product suitable for refining in that larger pieces and less defibration during pretreatment require greater working of the broke in the refining step and the resultant fluff is scorched and/or contains an unacceptable percentage of fiber bundles. Where the broke includes filaments bonded to the cellulosic sheet, many pieces of broken filaments have quantities of fibrous matter remaining adhered thereto. The pieces and separated matter, i.e. the reducer product, is characterized also by its bulky state wherein the pieces appear crumpled and larger and smaller pieces are mixed with separated fibers and small bundles of fibers making the re ducer product suitable for subsequent refining.

The pretreatment of the broke is enhanced by removing heat as it is generated within the reducer apparatus and thereby increasing the through-put capability of the apparatus. The degree of cooling is adjusted to prevent deleterious softening or melting of the particular plastic being processed under the conditions of work being done on the broke by the reducer.

A suitable reducer apparatus is identified as Model 100, available from the Eidal International Corporation, Albuquerque, N. Mex. This apparatus is depicted in FIGS. 2 and 3 and includes a plurality of sets 11 of freely rotatable toothed gears 12 whose peripheries are disposed in regulated proximity to a plurality of bar elements 14 disposed on the inner wall 16 ofa housing 18 which circumscribes the several gears and tapers inwardly from its top to bottom to define an annular space or gap 24 between the gears 12 and the housing, such gap narrowing from the top of the apparatus to its bottom. The tips 20 of the teeth on the gears 12 are generally flat. Similarly, the bars 14 are provided with generally flat surfaces 22 facing the flat gear teeth tips in opposing working relationship within the annular space or gap 24 therebetween. The gears 12 in each set 11 are disposed in a stack with several sets being mounted between horizontal platforms 25 and 25' which are rotated by a shaft 23 turned by a motor 31 connected to the shaft 23 through a belt drive 33 to carry the sets of toothed gears about the inner circumference of the housing 18. Each gear is independently rotatable about a shaft 27 relative to its mates and is caused to turn about shaft 27 incident to contact with broke disposed in the space 24 between the gear teeth and the bars 14. The shaft 27 of each set of toothed gears 12 resides in a radial notch 29 provided in each gear to provide a degree of freedom of movement to the gear in a radial direction, depending upon the mate rial disposed in the space between the gear teeth and the bars 14 on the housing wall 16. Hard clumps of material in the space thus force the gears radially inwardly temporarily until the clump is broken down.

Material to be acted upon by the apparatus is fed into the top 26 of the reducer and is subjected to a reducing action as the material passes to the bottom and out of the apparatus. The apparatus includes a massive breaker arm 41 near the infeed thereof to initially contact and break down large pieces or quantities of material. Reduction of the broke and/or pulp is effected initially by the breaker bar and subsequently by action of the broke upon itself as it is layered with the annular gap 24 betweenthe working surfaces of the gears 12 and the bars 14.'The outer wall 18 of the reducer is tapered inwardly to a lesser diameter adjacent the bottom of the upright reducer causing the broke to be progressively urged toward the gears 12 and maintain a layer of broke in the annular space 24 between the gears 12 and bar 14 thereby keeping the broke working upon itself as it is further reduced to smaller pieces.

The extent of the size reduction accomplished in the reducer is adjusted by choice of the proximity of the toothed elements 12 to the bars 14 on the outer housing 18 of the apparatus and the residence time of the material within the reducer. The space or gap 24 between the gear tooth faces 20 and the faces 22 of the bars 14 at the bottom of the space suitably is between about 1% and /1 inches, with a inch space being preferred. The gap distance at the top of the space 24 depends in part upon the material beingprocessed and the gap distance at the bottom but usually is less than about 2 inches.

The pretreated broke passes from the reducer l0 through an outlet 21. Adjustment of the residence time of the broke within the reducer is suitably made by providing a radially adjustable restrictor 28 immediately upstream of the outlet 21 of the reducer, the radial position of the restrictor being changed to permit more or less outflow of material from the reducer per unit of time. A suitable restrictor comprises a flat annular ring divided into

sections

35 and 37 which are adjustably held in a selected radial position by means of bolts 39.

Larger through-put of material through the pretreatment step is made possible by cooling the material in the reducer sufficiently to keep the temperature of the material below that temperature at which the plastic matter softens and/or melts, thereby reducing the occurrence of masses of plastic and fibers. Such masses tend to clog the reducer apparatus and reduce its operating efficiency, and at times can even completely stop its operation. One suitable means for controlling the temperature of the material within the reducer is to flow air through the interior of the reducer while it is in operation. The quantity of air flow employed depends in large part upon the desired degree of cooling which in turn is dependent primarily upon the type of plastic involved, the ratio of plastic to cellulosic matter and the rate of through-put sought for a given reducer apparatus. Other means for controlling the temperature of the material within the reducer will be apparent.

In the illustrated method, the product from the reducer is conveyed, preferably by pneumatic means, from the reducer to a storage chest 30 for retention and subsequent feeding to one or more refining stations 32. When employing the preferred pneumatic conveying means, the reducer product is entrained in air at the outlet of the reducer and fed through a separator, such as a cyclone separator 34, which collects the product from the air stream and dumps it into the storage chest while diverting the air through a filter system (not shown) and thence to the atmosphere. The reducer product is held in the storage chest for dispensing and conveying, as by an air stream, on demand to one or more refining stations 32 through a flow diverter 36 thereby providing for the supplying of reducer product to several refining stations from a single storage unit and resultant efficient marriage of the disclosed method to one or more production lines where the refined fluff product is incorporated into an absorbent product such as a disposable diaper.

At the refining station, the reducer product, which includes broke and pulp, is broken down, the cellulosic fibers being generally separated one from another and the plastic matter being refined to generally discrete small particulates to form afluff containing plastic particulates dispersed among the cellulosic fibers, and delivered to a production line as a weighed stream. In the illustrated method, the broke and pulp reducer product mixture is air conveyed from the storage chest 30, through a flow diverter 36, to a cyclone separator 38 where the reducer product is detrained from the air stream and dumped onto a weigh belt 42 from which it is introduced, by means of a chute 46 a belt conveyor 48, as a measured (by weight) stream into a refiner 50. Several production lines may be fed from a single weigh belt 42 through the use of a chute 46 having a plurality of

compartments

52 and 54, one compartment feeding each production line. i

A preferred refiner comprises a disc refiner of the type generally known in the art as a Bauer refiner. The refiner preferably employs a pair of opposed and oppositely rotating discs whose opposed faces are provided with radial bars having a minimum of rough edges which tend to snag and accumulate fibers or filaments. The faces of the bars on the opposed discs normally are spaced apart by a few thousandths of an inch to define a refining region therebetween. The discs, which conventionallyare each about 24 inches in diameter, normally are rotated at respective speeds of about 1,750 revolutions per minute. The fragments are received between the opposed faces of the discs, which are spaced apart by a gap of between about 0.040 and 0.120 inch, and reduced to a fluff by the action of the counterrotating discs on the pretreated material.

In one type of broke, i.e., the broke generated in the manufacture of a disposable diaper having a filamentreinforced cellulose cover sheet and a polyethylene flow control sheet less than about 0.00l inch thick, the plastic matter constitutes about twenty percent, by weight, of the broke. This broke is not satisfactorily processed to a fluff by passing the broke alone through a refiner in the substantial absence of water due to the heat generated in the refiner. The plastic material softens when heated and, upon subsequent cooling, forms unmanageable agglomerates of cellulosic fibers and plastic. It has been found, however, that by preliminarily treating the broke as disclosed hereinbefore and adding thereto a quantity of pulp, i.e., cellulosic fibers, such that the percentage by weight of plastic in the broke is reduced to less than about 30 percent, the-dry broke is readily processed through the refiner without scorching or other undesirable effects upon the material. This processing is successfully accomplished while operating the refiner in a conventional manner and using normal operating parameters of the refiner, including conventional cooling.

The pulp diluent is suitably added to the broke at any time prior to refining. The addition of the pulp to the broke, however, preferably takes place prior to pretreatment of the broke so as to take advantage of the mixing of the pulp and broke which occurs in the reducer apparatus and during handling of the reducer product subsequent to the pretreatment and prior to refining. For example, in the preferred air conveyor, considerable mixing occurs to aid in dispersing the broke and pulp reducer product so that a substantially uniform mixture with free moisture removed is fed to the refiner and a uniform fluff is formed. Some forms of broke, in the form of rejected disposable diapers for instance, may include a quantity of cellulosic fibers as the absorbent pad thereof, thereby dictating that these cellulosic fibers pass through the reducer. Additional cellulosic fibers, i.e., pulp, if needed to develop the proper ratio of fibers to plastic, are suitably added to the broke either prior to or following the pretreatment step but in any event prior to the refining step.

The reason or reasons why the plastic-containing fragments do not clog the refiner and/or form agglomerates as experienced when processing fragments having greater percentages of plastic are not known since the action of the refiner would appear to be the same in either instance. It has been found, however, that the pretreatment of the plastic-containing material which is carried out in the reducing apparatus provides a feed material which, when properly diluted with dry pulp, can be processed successfully through a refiner of the type described. Considerable variance in the degree of such preliminary treatment is permissible but when about 50 percent of the fibers have been freed as individual fibers or small bundles of fibers and most of the fragments are of less than about one and one-half inches in their major dimension satisfactory results are obtained in the refining step. Substantially less preliminary treatment increases the work required of the refiner to produce an acceptable fluff and increases the occurrence of heat build-up in the refiner with the accompanying undesirable results. Substantially more preliminary treatment appears to provide little increased benefit in the refiner, hence is economically wasteful.

A generally uniform and constant output from a refiner is obtained by use of the weigh belt 42 which feeds reducer product to the refiner in a measured stream. The refiner 50 thus is provided with a controlled input with the result that the output thereof is maintained suitable to satisfy the fluff demand of the production line. The output from the refiner is passed to a production line for incorporation into an absorbent product. The fluff is particularly useful in forming the absorbent pad of a disposable diaper or sanitary napkin and is made a part of the product by production line means known in the art.

EXAMPLE I Employing the method described herein, broke comprising discarded disposable diapers including cellulosic tissue reinforced with two SO-denier nylon filaments adhered to each inch of tissue width with a polyvinyl alcohol adhesive and including a polyethylene barrier sheet about 0.075 inch thick weighing about 3 grams was fed to a reducer simultaneously with cellulosic pulp in sheet form. The plastic content of the diapers was about 20 percent by weight. The infeed to the reducer comprised about 85 percent cellulosic pulp and about 15 percent diaper broke, the plastic content of the infeed thus being about 2.25 percent, by weight. The reducer apparatus comprised an Eidal Model 100 described hereinbefore with the tips of the toothed gears adjusted to within about M: inch of the flat surface of th'e bar s'adjaent'theliottom part of the iri'fe'rior housing wall thereof. The gap between the tips of the gear teeth and the flat bar surfaces near the top of the duser as bQRLZ nc s About .0.0910 2.0 cubic feet of air was flowed through the apparatus per minute for cooling purposes. The outflow from the reducer was adjusted to develop a residence time of the material within the reducer such that the broke and pulp were reduced to a product wherein about 50 percent of the cellulosic fibers were separated into individual fibers or small bundles of fibers, an appreciable portion of the plastic matter was broken into small pieces, and a relatively small portion comprised larger pieces having a respective major dimension greater than about 1% inches. This reducer product was conveyed to a Bauer refiner and processed therethrough without scorching or other undesirable consequence while employing conventional operating parameters of the refiner. The resultant fluff comprised small pieces of plastic and cellulosic fibers which were generally separated one from another. Most of the plastic pieces were small, e.g. less than about one fourth inch in length. Some pieces were as long as about one inch in length, especially the plastic filaments, but no substantial entanglement of the broken filaments was noted. This fluff product was incorporated into a disposable diaper as the absorbent pad thereof and tested.

EXAMPLE ll Fifteen percent, by weight, of diaper broke comprising about 20 percent, by weight, of plastic material was processed with about percent, by weight, of cellulosic pulp'as in Example I. The diaper broke of this Example ll included polyethylene sheets which made up about 6 percent, by weight, of the plastic content of the diaper broke. The plastic content of the infeed to the refiner thus was about 3 percent, by weight. The addition of pulp insufficient to dilute the plastic content of the infeed to the refiner to at least about four percent, by weight, was noted to result in unfavorable processing through the refiner. No problems were encountered during processing. Diapers made up using the fluff of this example also were tested.

A disposable diaper made from primary pulp and having about 35 to 40 grams of cellulosic matter therein will normally exhibit an absorptive capacity in the range of between about 80 to about grams of water (employing 4 gram samples and using the ORF Sinking Basket Test). Diapers made with the fluff product disclosed herein exhibited absorptive capacities in the range of between about 80.8 to about 98.2 grams of water and rates of absorbency of between about 3.5 to about 8.9 seconds. Thus the absorptive capacities of the diapers which were made with the disclosed fluff were within the range of this property for diapers made from primary pulp fluff. The diapers also exhibited absorbency rates which substantially approximated the absorbency rates of primary pulp fluff diapers. in some instances, the diapers having fluff as disclosed herein exhibited an appreciable increase in absorptive capacity which appeared to derive from the presence of the plastic matter in the fluff. Such observed increase is particularly striking inasmuch as the plastic matter in the fluff is hydrophobic and hence is not absorptive itself.

The fluff product of the Examples had a good appearance and exhibited no undesirable agglomeration of material. The filaments, which were continuous in the broke, were observable in the fluff as relatively small particulates. Many particulates were less than one fourth inch in length. The polyethylene sheet was similarly reduced in size with only infrequent occurrences of visually observable larger pieces of plastic. Either with or without the observed improvement in absorptive capacity, the present method produces a fluff which represents a substantial savings in the manufacture of a disposable product by reason of the capability of the present method to convert a heretofore waste product into a useful absorptive material. As referred to earlier, plastic-containing broke has heretofore been of little, if any, value. By means of the present method, such broke is converted to a fluff which is substantially equivalent to fluff formed from primary pulp as regards its absorptive properties and physical appearance.

While the present description has included specific examples and embodiments it will be understood that there is no intent to limit it by such disclosure, but rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A method for converting plastic-containing cellulosic broke to substantially separated fibers and particulates of plastic matter in the substantial absence of a liquid comprising the steps of pretreating said broke to condition it for refining,

said pretreatment comprising breaking said broke to pieces and working said pieces to reduce their size, substantially all the reducing action being accomplished by the action of said pieces upon themselves until only a minor portion of the plastic matter has a major dimension greater than about 1% inches and of the order of 50 percent of the cellulosic matter is freed as individual fibers or small bundles of fibers,

conveying said pretreated broke to a refining station,

dry refining said broke to a material wherein the cellulosic fibers are substantially separated one from the other and the plastic matter is substantially reduced to pieces, an appreciable portion of which have a major dimension of less than about onefourth inch, and adding cellulosic pulp to said broke prior to refining in an amount such that said plastic matter amounts to less than about 30 percent by weight of the material prior to dry refining.

2. The method of claim 1 wherein said pretreatment includes the step of layering said broke in the course of said pretreatment step.

3. The method of claim 1 and including the step of feeding said refined product directly to a production line for producing an absorbent product on a generally continuous basis.

4. The method of claim 3 and including the step of controlling the conveyance of fragments to said refining station after pretreatment at a rate substantially equal to the demand rate for said production line.

5. The method of claim 1 wherein said cellulosic pulp is added to said broke prior to the pretreatment step.

6. The method of claim 1 wherein said broke comprises disposable diapers including plastic reinforcing filaments and whose plastic content is about percent, by weight, and wherein the quantity of added cellulosic pulp reduces the plastic content of the infeed to the refining step to less than about 4 percent by weight.

7. A method for converting plastic containing cellulosic broke to substantially separated fibers and particulates of plastic matter in the substantial absence of a liquid comprising the steps of admixing a quantity of said broke and a quantity of cellulosic pulp, said resultant mixture having less than about 30 percent, by weight, of plastic material therein, pretreating said mixture to condition it for refining, said pretreatment comprising breaking said mixture to pieces and mechanically working said pieces to reduce their size, substantially all the reducing action being accomplished by the action of said pieces upon themselves until only a minor portion of the plastic matter thereof has a major dimension greater than about one an one-half inches and of the order of 50 percent of the cellulosic matter is freed as individual fibers or small bundles of fibers,

conveying said pretreated mixture to a refining station, and, dry refining said pretreated mixture to a material wherein the cellulosic fibers are freed and substantially separated one from the other and the plastic material is substantially reduced to pieces, an appreciable portion of which have a major dimension of less than about one-fourth inch, said separated fibers and plastic pieces in the aggregate being of a size and quality suitable as an absorbent fluff for disposable absorbent products.

8. A method for ,converting plastic-containing cellulosic broke to substantially separated fibers and particulates of plastic matter in the substantial absence of a liquid and marrying such conversion method with a production line for producing disposable absorbent products including a fluff comprising the steps of pretreating said broke to condition it for refining,

said pretreatment comprising breaking said broke to pieces and mechanically working said pieces to reduce their size, substantially all the reducing action being accomplished by the action of said pieces upon themselves until only a minor portion of the plastic matter thereof has a major dimension less than about 1% inches and of the order of about 50 percent of the cellulosic matter is freed as n v d fibers or m llhun espf,film

pneumatically conveying said pretreated pieces to a 7 storage area,

dispensing said pieces from said storage area,

weighing at least one preselected quantity of said dispensed pieces, directing said weighed quantity to a refiner, said weighed quantity being substantially equivalent to the fluff demand, by weight, of said production line,

refining said weighed quantity, and

delivering said refined quantity to said production line.

9. An improved fluff produced by the process of claim 1.

- UNITED STAT S PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,773,613 I W November 20, I973 lnvehtoflsy Charles A. Lee and Frederick M. Granberg It is certified that error appears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Col. 4, line 60, change "bar to bar,s

Col. -5, last line, between "'46" and a, insert -'and..

Col. 9, line 18; following "matter" (the word matter being broken between lines 17 and 18) and'before "has", insert --th'ereof--.

Col. 10, line 11, following "one" and before one-half" change '"an" to -and-.

Signed and sealed this 6th day of August (SEAL) Attest:

MCCOY M. GIBSON, JR. 0. MARSHALL DANN Attesting Officer Commissioner of Patents v FORM PO-105O (10-69) Us COMM-DC wan-pee I I I 9 LLS. GOVERNMENT PRINTING OFFICE IBIS 0-35-334,

Claims

2. The method of claim 1 wherein said pretreatment includes the step of layering said broke in the course of said pretreatment step.
3. The method of claim 1 and including the step of feeding said refined product directly to a production line for producing an absorbent product on a generally continuous basis.
4. The method of claim 3 and including the step of controlling the conveyance of fragments to said refining station after pretreatment at a rate substantially equal to the demand rate for said production line.
5. The method of claim 1 wherein said cellulosic pulp is added to said broke prior to the pretreatment step.
6. The method of claim 1 wherein said broke comprises disposable diapers including plastic reinforcing filaments and whose plastic content is about 20 percent, by weight, and wherein the quantity of added cellulosic pulp reduces the plastic content of the infeed to the refining step to less than about 4 percent by weight.
7. A method for converting plastic containing cellulosic broke to substantially separated fibers and particulates of plastic matter in the substantial absence of a liquid comprising the steps of admixing a quantity of said broke and a quantity of cellulosic pulp, said resultant mixture having less than about 30 percent, by weight, of plastic material therein, pretreating said mixture to condition it for refining, said pretreatment comprising breaking said mixture to pieces and mechanically working said pieces to reduce their size, substantially all the reducing action being accomplished by the action of said pieces upon themselves until only a minor portion of the plastic matter thereof has a major dimension greater than about one an one-half inches and of the order of 50 percent of the cellulosic matter is freed as individual fibers or small bundles of fibers, conveying said pretreated mixture to a refining station, and, dry refining said pretreated mixture to a material wherein the cellulosic fibers are freed and substantially separated one from the other and the plastic material is substantially reduced to pieces, an appreciable portion of which have a major dimension of less than about one-fourth inch, said separated fibers and plastic pieces in the aggregate being of a size and quality suitable as an absorbent fluff for disposable absorbent products.
8. A method for converting plastic-containing cellulosic broke to substantially separated fibers and particulates of plastic matter in the substantial absence of a liquid and marrying such conversion method with a production line for producing disposable absorbent products including a fluff comprising the steps of pretreating said broke to condition it for refining, said pretreatment comprising breaking said broke to pieces and mechanically working said pieces to reduce their size, substantially all the reducing action being accomplished by the action of said pieces upon themselves until only a minor portion of the plastic matter thereof has a major dimension less than about 1 1/2 inches and of the order of about 50 percent of the cellulosic matter is freed as individual fibers or small bundles of fibers, pneumatically conveying said pretreated pieces to a storage area, dispensing said pieces from said storage area, weighing at least one preselected quantity of said dispensed pieces, directing said weighed quantity to a refiner, said weighed quantity being substantially equivalent to the fluff demand, by weight, of said production line, refining said weighed quantity, and delivering said refined quantity to said production line.
9. An improved fluff produced by the process of claim 1.