WO1999033652A1

WO1999033652A1 - Non-continuous fiber reinforced plastics and method of making same

Info

Publication number: WO1999033652A1
Application number: PCT/US1998/027370
Authority: WO
Inventors: Albert S. Elias
Original assignee: Fiberand, Inc.
Priority date: 1997-12-30
Filing date: 1998-12-23
Publication date: 1999-07-08
Also published as: TW397761B; AU2203799A

Abstract

Non-continuous fiber reinforced plastics utilizing non-continuous fibers and a method to facilitate impregnation of non-continuous fibers with sizing and a coupling agent into a continuous sheet moved through a first dryer, a vertical press and a second dryer and pressure rollers to form a cured, compressed and configured sheet reinforced with non-continuous fibers. The sheet can be shredded into particles of a size to be discharged into a compounding machine along with plastic pellets or the sheet may be laminated with plastic sheets to form a non-continuous fiber reinforced plastic panel.

Description

NON-CONTINUOUS FIBER REINFORCED PLASTICS AND METHOD OF MAKING SAME

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the formation of non-continuous fiber reinforced plastics and a method to facilitate the impregnation of non-continuous fibers with sizing and treatment with coupling agents. The resulting impregnated non-continuous fibers can be used to reinforce various .kinds of plastics.

2. Description of the Prior .Art

Most plastic products use glass fibers as reinforcement which works well in plastic. However, glass fibers are relatively expensive and materially increase the manufactuiing cost of plastic products reinforced with glass fibers. Glass fibers are formed by heating glass to a molten state and introducing the molten glass through nozzles with the molten glass being pulled rapidly or attenuated into a thin continuous fiber. A group of individual continuous fibers or filaments then usually pass through a water spray and over an applicator w ch provides a protecting coating or s:izing with the fibers then being gathered into a bundle or strand. Continuous fibers, by nature, can be pulled through sizing baths, over rollers with coatings or between rollers, where at the same time further elongation of the fibers is achieved. The impregnated fibers are thereafter wound onto spools, still in bundles of 200-2000 fibers, glued together by the sizing. These fiber-strands can be woven into glass textiles, laid to non wovens, chopped to size, between 6-25 mm or milled into a fiber-mass with randomized length. Since the fibers are pre-impregnated, their surface binds to the plastic. These different fiber products are therefore the prefeired reinforcement for plastics. However, the prior art does not include the product or method of the present invention in which non-continuous fibers are impregnated with sizing .and coupling agents with the resulting impregnated fibers forming a plastic reinforcement fiber that circumvents the disadvantages of non-continuous fibers. The impregnated non- continuous fibers of this invention produces plastics that can replace glass fiber reinforced plastic at considerably less cost and in any type plastic where clear transparency is not a requirement. SUMMARY OF THE INVENTION

An object of the present invention is to transfer non-continuous fibers into fiber products that can be used for plastic reinforcement and a novel method of achieving this object by thorough impregnation by sizing and a coupling treatment and a compressed configuration in order to convert the normally fluffy fiber mass dense enough to become free-flowing in feeding equipment and dense enough to be easily admixed with plastic in pelletized form.

Another object of the invention is to provide a method of making non-continuous fiber reinforced plastics in which the non-continuous fibers are formed into a sluiry that is laid onto a horizontally moving screen as a wet web or sheet for separating liquid material from the sluiry with the partially dried sheet of slurry on the screen then passing through a vertical press where a coupling agent is added.

A further object of the invention is to provide a method as defined in the preceding objects in which a sizing can be added to the non-continuous fiber slurry and a drying procedure occurs prior to the vertical press or the sizing can be added to the wet sheet prior to the first dryer. A coupling agent is added to the partially dried sheet at the vertical press or just prior to the vertical press to maintain the integrity of the sheet. A second drying and sheet compressing procedure occurs subsequent to the vertical press so that the compressed and dried sheet exiting from the moving screen can then be shredded into strips for feeding into a compounding machine or extruder along with plastic pellets to foim reinforced plastic products or the compressed and dried sheet can be used in a layered arrangement with plastic sheets to form a fiber reinforced plastic panel. The non- continuous fibers in the strips or sheets are longitudinal, transverse or at various angular relations to the other fibers to increase the strength characteristics of the plastic reinforcement fiber strip or sheet longitudinally and transversely to provide a more constant strength characteristic throughout the area of a plastic product formed from the shredded strips or sheet formed by the method of this invention. These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a schematic illustration of the method of making non-continuous fiber reinforced plastics of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In forming the plastic reinforcement product of the present invention .any non- continuous fiber can be used, such as mineral fibers from rock or slag, cellulosic fibers, synthetic fibers or the like normally as a fluffy mass produced in a conventional manner and having a thickness or diameter of approximately 3 to 5 microns and a length of 50 to 3,000 microns. The non-continuous fibers are mixed with water to form a flowable slurry S having a concentration usually between OJ-5.0% solids (fiber) depending on the conventional equipment that will use the non-continuous fiber reinforced plastics produced by the method. The concentration determines the viscosity of the slurry S which is supplied into a container 10. The slurry is maintained at ambient temperature 15-30°C and admixed with a siang material which is conventional and can include epoxy ester, bisphenolic polyester or starch is introduced into the fiber slurry at this point or at a later point. The slurry S is then discharged through a conduit 12 onto a horizontally disposed moving screen 14 in the form of a wet sheet of material 16. Mixing the s.izing with the sluiry in container 10 can be expensive and the sizing can be added to the wet sheet 16 by spraying or the like after the slurry has been placed on screen 14. At the point of deposit of the slurry onto the screen 14, a trough 18 underlies the screen for collecting water W drained from the slurry. A discharge line 20 may be provided for the water or liquid forming the slurry. The screen and the wet sheet 16 proceeds through a dryer 22 to partially dry sheet 16 to help keep the sheet together. The partially dried sheet then moves downwardly vertically a very short distance to and through a vertical size press 24 Wabich includes a pair of opposed rollers. The coupling agent is introduced onto sheet 16 or introduced at the vertical size press 24. Various conventional coupling agents may be used including silanes, amino, diamino, epoxy, vinyl silanes and the like depending upon the resin material to be utilized. The sheet of material 16 then is positioned on a second moving screen 26.and passes through a second dryer 28 and a pair of compression rollers 30 to m^tain a pressure on the sheet while it is being dried to a final dried product. The dried sheet is then discharged at exit 32. The distance from belt 14 to size press 24 and from size press 24 to lower screen 26 should be as short as possible to maintain the integrity of sheet 16 during its movement to dryer 28. The dry sheet which has been compressed and configured by the press 24 and dryer and pressure rollers 30 has a thickness about 1-3 mm and weight of about 1-2 kg/m². The diy sheet may be shredded to a size about 1 X 3 X 10 mm to 3 X 3 X 10 mm and can be fed to the compounding screw along with plastic pellets in a well .known and conventional manner to form various reinforced plastic products. Alternatively, the diy sheet may be layered with sheets of plastic to form non-continuous fiber reinforced p.anels of various configurations including vehicle body panels and the like. The moisture remaining in the sheet after the vertical press 24 is approximately

20% and the moisture remaining in the sheet 16 after the final dryer 28 is less than 1%. The panel is cured under temperature conditions of approximately 150 to 180°C under a moderate pressure which will not crush the fibers.

.All of the equipment used in this invention is standard industrial equipment in order to maintain product cost of the non-continuous fiber reinforced plastics produced at exit 32 at a minimum. The non-continuous fiber reinforced plastics of this invention can be used in any plastic product that does not require clear transparency at a cost substantially less than plastic products formed by using glass fiber reinforcement.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. WHAT IS CLAIMED AS NEW IS AS FOLLOWS:

1. A plastic reinforcement product comprising non-continuous fibers impregnated with siang and a coupling agent, said non-continuous fibers being oriented in various relative angular relations when the product is cured. 2. The product as defined in claim 1 wherein said non-continuous fibers have a thickness of approximately 3-5 microns and a length of approximately 50-3,000 microns. 3. The method of foπning a plastic reinforcement product comprising the steps of supplying non-continuous fibers, forming a slurry by mixing water with the non- continuous fibers, admixing a siang material with the slurry, depositing the slurry on a horizontally disposed moving screen in the foπn of a wet sheet, partially drying the wet sheet, adding a coupling agent to the sheet and moving the sheet through a vertical press, disposing a compressed and configured sheet on a moving screen below the press, final diying and exerting compression pressure on the sheet while on said moving screen below the press, and discharging the dried sheet at an exit station. 4. The method as defined in claim 3 in which the moisture content of the wet sheet is reduced to 20% at the vertical press and to less than 1% at the second dryer.

5. The method as defined in claim 4 wherein said non-continuous fibers have a thickness of about 3-5 microns and a length of about 50-3,000 microns.

6. The method as defined in claim 4 wherein said dried sheet has a weight of about 1-2 kg/m² and a thickness of about 1-3 mm.

7. The method as defined in claim 4 wherein the coupling agent is about .2%.

8. The method as defined in claim 4 wherein said cured sheets is shredded to a size of about 1 X 3 X 10 mm to about 3 X 3 X 10 mm.

9. The method as defined in claim 4 wherein said cured sheet is cut to a panel size and laminated to a resin sheet to foπn a non-continuous fiber reinforced panel.

Claims

AMENDED CLAIMS[received by the International Bureau on 10 Dune 1999 (10.06.99); original claims 1-9 replaced by amended claims 1-9 (2 pages)]WHAT IS CLAIMED AS NEW IS AS FOLLOWS:

1. A plastic reinforcement product comprising loose, bulky, noncontinuous fibers impregnated with sizing and a coupling agent and oriented in various relative angular relations compressed into compressed cured sheets for shredding into pellets for use in compounding equipment.

2. The product as defined in claim 1 wherein said noncontinuous fibers have a thickness of approximately 3-5 microns and a length of approximately 50-3,000 microns.

3. The method of utilizing loose, bulky, noncontinuous fibers to form compressed sheets which can be shredded into pellets for introduction into compounding equipment together with pellets of different plastics to produce fiber reinforced plastic objects of different shapes or layered with sheets of different plastics to produce fiber reinforced heat laminated plastic panels, said method comprising the steps depositing a slurry of noncontinuous fibers, water and sizing agent onto a screen as a wet sheet., partially drying said wet sheet, applying a coupling agent to said partially dried wet sheet, compressing said partially dried wet sheet with coupling agent, drying and curing said compressed sheet.

4. The method as defined in claim 3 in which the moisture content of the wet sheet is reduced to 20% of the total weight of the sheet at the vertical press and to less than 1% of the total weight of the sheet at the second dryer.

5. The method as defined in claim 4 wherein said noncontinuous fibers have a thickness of about 3-5 microns and a length of about 50-3,000 microns.

7. The method as defined in claim 4 wherein the coupling agent is about .2% of the total weight of the slurry.

AMENDED SHEET (Affi JΞ19)

8. The method as defined in claim 4 wherein said cured compressed sheet is shredded to a size of about 1 X 3 X 10 mm for introduction inot compounding equipment with pellets of different plastics.

9. The method as defined in claim 4 whererin said c ured sheet is cut to a panel size and laminated to a resin sheet for form a noncontinuous fiber reinforced panel.