BIOFIBER FILM

Abstract

A thin film laminate having high percentages of biomass microparticles, and methods of making the same involve mixing biomass-microfibers with an adhesive, wherein the mixture comprises at least 50% biomass-microfibers by weight, heating the mixture above the melt temperature of the adhesive, and disposing the heated mixture between plastic sheets.

Claims

1. A method of making a laminate; comprising: mixing biomass-microfibers with an adhesive and optional additives wherein the mixture comprises at least 50% biomass-microfibers by weight; heating the mixture above the melt temperature of the adhesive; and disposing the heated mixture between plastic sheets while under compression to form a laminate having a desired thickness.

2. The method of claim 1, wherein the compression of adhesive with biomass and plastic sheet is performed using a roller system, a belt/roller system, opposing rollers, a belt system, or a combination thereof.

3. The method of claim 1, wherein plastic sheets are selected from BOPET (bi-oriented PET) polypropylene, high density polyethylene, PE, polylactic acid or combinations thereof.

4. The method of claim 1, wherein the mixture comprises at least 60% biomass-microfibers by weight.

5. The method of claim 1, wherein the mixture comprises at least 80% biomass-microfibers by weight.

6. The method of claim 1, wherein the mixture comprises at least 90% biomass-microfibers by weight.

7. The method of claim 1, wherein the biomass-microfibers have a maximum dimension less than 20 m.

8. The method of claim 1, wherein the biomass-microfibers have a maximum dimension less than 15 m.

9. The method of claim 1, wherein the biomass-microfibers have a maximum dimension less than 10 m.

10. The method of claim 1, wherein the optional additives include calcium carbonate in an amount from 1% to 20% of the mixture by weight.

11. A laminate having a plurality of layers including a biomass layer that comprises a mixture of biomass-microfibers, at least one adhesive, and optionally one or more additives, wherein the total mass of resin, adhesive and optional additives in the biomass layer is less than the mass of the biomass-microfibers.

12. The laminate of claim 11, wherein the mixture comprises at least 60% biomass-microfibers by weight.

13. The laminate of claim 11, wherein the mixture comprises at least 80% biomass-microfibers by weight.

14. The laminate of claim 11, wherein the mixture comprises at least 90% biomass-microfibers by weight.

15. The laminate of claim 11, wherein the biomass-microfibers have a maximum dimension less than 20 m.

16. The laminate of claim 11, wherein the biomass-microfibers have a maximum dimension less than 15 m.

17. The laminate of claim 11, wherein the biomass-microfibers have a maximum dimension less than 10 m.

18. The laminate of claim 11, wherein the optional additives include calcium carbonate in an amount from 1% to 20% of the mixture by weight.

19. A method of making a laminate, comprising: (a) milling biomass in a mill to produce biomass-microfibers; (b) mixing the milled biomass-microfibers with an adhesive; (c) heating the mixture to a temperature above the melt temperature of the adhesive; (d) blending the heated mixture with calcium carbonate to form a heated blend; (e) disposing the heated blend between plastic sheets while under compression to form a laminate having a desired thickness; wherein the blend comprises at least 50% biomass-microfibers by weight and from 1% to 20% calcium carbonate by weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIGS. 1A and 1B illustrate a comparison of compounded resin with compressed adhesive densities (FIG. 1B) against conventional thin film components (FIG. 1A).

[0016] FIG. 2 illustrates the thin film components and structure contemplated for one embodiment.

[0017] FIG. 3 illustrates the thin film components and structure contemplated for another embodiment.

[0018] FIG. 4 illustrates a method of assembly of the components as exemplified by one of the embodiments.

[0019] FIG. 5 illustrates a method of assembly of the components as exemplified by another embodiment.

DETAILED DESCRIPTION

[0020] A method for fabricating a multi-lamina composite consisting of blown or cast-film bonded to each side of a thicker biomass-based core is disclosed. The method increases the percentage of biomass in thin film products beyond prior art while reducing or eliminating percentages of more expensive materials such as compounded resin blown film. The distances and volume of space between well-dispersed biomass-microparticles in resin-based compounding results in minimal direct contact between biomass microparticles. In a 40% biomass-based plastic, resins and additives can be effectively used as fillers between bio-microfibers beyond their primary practical effective purpose of particle-to-resin adhesion.

Multi-Part Bio-Based Laminate

[0021] The method for production of multi-lamina composites can include hammermilling biomass, supplying an extremely thin layer or layers of adhesives by rolling or other means, and/or milling adhesives, and optionally milling other additives to fine particle size to match the size of biomass microfibers. Other steps can include air classification of biomass, mixing biomass with adhesives, heating the mixture of biomass microfiber and adhesive, optionally with other additives, spreading the mixture onto a roller/moving belt or the like, or rolling any or all of the above, compression rolling of a single laminate, and cooling and hardening of the laminate.

[0022] Hammermills or other grinding systems containing a 0.5 mm hole size hammermill screen such as those manufactured by Prater, are used to grind whole oat hulls from oat processors such as Quaker or General Mills to achieve an average particle size of 250 m; adhesives, and optional additives such as CaCO3, strength compatibilizers, coloring agents may be ground in the same way as described above for oat hulls. Further, any type of biomass can be processed for use in the disclosed processes and laminates.

[0023] Hammermilled oat hulls, or unground oat hulls are milled into smaller microfibers with one top particle size of 16 m, or 10 m to produce a final thin film product such as crispy snack bags approximately 2 mil consisting of laminates glued together, each laminate having unique functions and dimensions within the final laminate product. Films consisting of greater than 2 mil thickness can be created with larger dimension biomass microfibers. Within the scope of this disclosure, top particle size is determined by the final film dimension where the preferred particle size is at or less than 20% of the final production dimension, while the function of high percentages of biomass and lower percentages of adhesive applies in all formula of this disclosure. The primary target for the disclosed product is 1-4 mil thickness.

[0024] In one embodiment, milling of biomass is performed in an attrition mill such as a Union Process attritor, or a combo attrition mill/classifier as manufactured by RSG, or a ball mill or similar mill manufactured by RSG and many other companies, or a rod mill as manufactured by Micro Grinding Systems, for up to 12 hours, or longer, using, in one embodiment, a preferred size ball media of , or combined with smaller sized media; e.g. 1/16 as an example; or rods in a rod mill of , or smaller, or larger: media changes can include tungsten steel for a denser, heavy media which lasts longer than the most metal media, and grinds faster than stainless steel due to density, for example; higher and smaller sized end product will determine the choice of media and residence.

[0025] Biomass microfiber separation is done using an air classifier to dis-agglomerate the agglomerates created in milling to extract 16 m, or 10 m and smaller top particle dimension size, with an average top dimension particle size of 4-6 m or for larger top particle size oat hull microfibers for larger dimension film up to 4 mil.

[0026] First pass in the dis-agglomeration step on finely milled oat hulls typically shows a profile containing approximately 30-40% 10 m particles of the feed to a top particle size of 16 m, or with additional passes through the classifier, and preferably, 10 m for use in 2 mil plastic laminates. The smaller microfibers extracted are herein called FINES; biomass microfibers separated away from FINES, consisting of microfibers greater in size than 16 mare hereinafter referred to as OVERS. Overs in the first or second pass represent approximately 70% of pre-milled inflow biomass and are further ground as described above using an attritor, rod or ball mills, attritor mills combined with continuous air classification. FINES from all classification are combined with other Fines at 16 or 10 m and OVERS combined with OVERS from other steps for further milling, dis-agglomeration and classification; additional fine grinding as described herein until at least 50%, 70%, 80%, 90% or 100% of original intake oat hulls have reached a target top particle size of 16 or 10 m. The biomass-microfibers can have a maximum dimension less than 20 m, less than 15 m or less than 10 m.

[0027] The biomass microfiber <16 m or <10 m FINES is mixed with pre-ground adhesive(s) such as 100 m average particle size, or as small as <16 m, or adhesive much larger but applied in any other form as a melt adhesive, a wet/fast drying adhesive, a binary adhesive, or any adhesive known to those skilled in the art, and optionally adding CaCO3, compatibilizers, and any other additives to improve adhesion, strength and flexibility; an example being 70% oat hull microfibers, 15% adhesives such as Arkema Platamid, or protein-based adhesive particles, optionally 15% CaCO3, results in an effective adhesion between particles, and adhesion between the biomass-based adhesive laminate, wherein the adhesive is molten, adheres to pre-made/blown or cast plastic laminates rolled, compressed or dried onto the outside of the composite laminate. Thicker strips of adhesives can be laid parallel to the flow of the laminate build over rollers, which are spread to small dimension thickness, on and in between described oat hull and other biomass microfibers to create internal and surface adhesive properties for the laminate. Spot application of adhesive in molten form can be utilized with molten adhesive.

[0028] In other embodiments; adhesives, CaCO3, and other additives (e.g., compatibilizers) are ground using similar methodology as described herein to similar top particle size, generally FINES, at or below 16 m. Further, cryogenic or refrigeration cooling may be employed to ensure the ground substrate is well below glass transition temperature for effective grinding. The mixture, either with or without calcium carbonate and/or additives, preferably comprise at least 50%, more preferably 60%, 80% or 90% biomass-microfibers by weight. Adhesives FINES may be larger than 14 m, as they have been found to melt sufficiently to compress, combine, spread and adhere with biomass and adjacent plastic thin film sheets under compressive energy and adhesive melt temperatures described below. One particle size option of adhesive FINES is 16 m. but average of 100 microns has been shown to work well for bind oat hull particles and to bind biomass-adhesive formula to plastic laminates added during heat and compression; high particle size adhesives can be practical, while not necessarily being optimal. The ratios of the components may vary depending on the thickness of final product, type of biomass and final construct specifications of the laminate.

[0029] Heating the low moisture biomass microfiber/adhesive/CaCO3 FINES mixture described above in any system known to persons skilled in the art at or above the melting point of a select adhesive, is pushed forward with a suitable mechanical device such as an internal metering screw with associated weight-loss measurement device to insure precision delivery of target flow rate of dry material mixture, while continuing to be pushed forward.

[0030] The heated mixture containing molten adhesive is metered and spread onto a roller or moving belt or other such compression device known to those skilled in the art; the mixture is evenly spread close to the final width of the complete laminated sheet.

[0031] The compression system rolls out the pre-measured mixture between rollers, or belts and rollers or other compression device for shaping and sizing to facilitate spreading a layer of the oat hull/adhesive/CaCO3 mixture at a prescribed thickness of 10-25 microns thick when targeting a final film laminate approximately 2 mil thick; In one embodiment, a single laminate consisting of oat hull microfibers, adhesive, optionally CaCO3 and other optional additives are compressed into a single laminate/adhesive.

[0032] In another embodiment, for the production of a MULTI-LAYER LAMINATE; oat hull/adhesive, CaCO3 and additives are fed onto a roller while pre-blown or cast plastic thin film laminates are fed parallel to the adhesive laminate which are glued to the adhesive laminate under heat and pressure, onto a roller, rollers or roller-belt or other compression system to form a multi-layer laminate, on one or two sides or on top and bottom of the biomass mixture in intimate contact with molten adhesive-biomass microfibers, continuing through the compression step to further shape and size the thickness of the composite laminate.

[0033] The single laminate oat hull/adhesive or the multi-laminate is cooled and cured by reducing the temperature below the prescribed adhesive molten point rapidly to ambient temperature, in the case of a multi-laminate, all laminates are glued together and are rolled up as a final product.

[0034] A combination of laminate layers is completed to mirror traditional plastic films used in snack food and other crispy food packaging. Print film sheets, vapor deposited aluminum vapor barrier or barriers, and final plastic sheets over bag interior vapor barriers, which can all be laminated using the biomass-based adhesive laminate as the glue on some or all adhesives required in laminating. Two feeds of blown-thin film sheets each from 1-20 m, preferably from 1-12 m thick, each consisting of any one of BOPET, polypropylene, high density polyethylene, Green Dot bio-resins, NatureWorks polylactic acid and any other bio-resins are fed continuously onto large opposing rollers through prescribed size gaps.

[0035] The combinations of any and all of the above embodiments are employed to optimize the effectiveness of the core process embodied in the various examples described herein.

[0036] In another embodiment, multiple types of bonding agents can be deployed together, separately and/or in various time points in sequence to achieve a first, fast or instant bonding, e.g. a superglue type of glue, followed by another, longer curing but strong glue for additional strength when fully cured, and optionally for added flexibility or stiffness. A bio-based, preferably protein-based, or a protein/carbohydrate-based adhesive is preferred and establishes a platform for a complete and cost-effective biobased and biodegradeable film product. Water-based, melt-adhesive or any adhesive suitable for food packaging may be employed within the disclosed laminates.

[0037] In one alternative embodiment, any additional adhesive formula may be applied to either one or two of the fed plastic thin film sheets as described herein in small particle, mist form, precisely measured for final pressurized distribution throughout the biomass-microparticles during next-step compression.

[0038] Alternatively in other embodiments, the same types of adhesives are applied in their liquid form in near simultaneous precision timing relative to compression. Water-based adhesive can be applied followed by a fast moisture removal step.

[0039] Immediately in front of rollers, metered biomass-microfiber and pre-applied adhesives, or microfibers and simultaneously applied adhesives, or pre-mixed biomass-adhesive-optional additives, immediately before the moving casings reach the compression roller, and other additives, or vapor deposited adhesives, or mist micro-drops, are instantly compressed by the compression roller and the fixed position roller, up to levels at which no reduction in volume can be achieved mechanically, or optionally to a pressure point and thickness less than described above to accommodate microflow of adhesives, additives and optionally hot resin melt through micro interstices within compressed particles. The greatest compression of the laminates is with the biomass microparticles; which is especially true when a wet adhesive has been applied and is being flash dried.

[0040] Thickness of the final laminate is product dependent and the inventive methods applied herein are not limited by specific product thickness or specific formulation, as compressive systems and biomass-microfiber/adhesive/additive formula are adjustable within the disclosed method.

[0041] FIG. 1 illustrates a comparison between conventional thin film components (FIG. 1A) and the components disclosed herein. FIG. 1B illustrates a biomass adhesive mixture along with plastic laminates on each side of the mixture in accordance with this disclosure. The figure further illustrates that the spaces between the particles has been reduced by crushing biomass microparticles together and reduces the need for expensive adhesives at the same time.

[0042] FIG. 2 illustrates a sectional view of the biomass-adhesive laminate; wherein all the layers of the laminate are shown.

[0043] FIG. 3 illustrates a core laminate; wherein a molten hot-mix of biomass microfibres, adhesives and additives mixture is poured onto a roller assembly. The hot-mix is then allowed to cool down.

[0044] FIG. 4 illustrates a basic multi-laminate; wherein the plastic sheets are introduced in the assembly and are compressed to attach on each side of the biomass-adhesive mixture. Further, an optional adhesive layer may also be added between the plastic sheets and the biomass-adhesive mixture on both sides for gluing purposes.

Examples

[0045] 14 m thick biomass-adhesive core laminate/adhesive laminate has been produced combining 10% Platamid 100 m particle size adhesive with 70% 10 moat hull microfibers and 20% CaCO3 under pressure in a Carver lab press at 205f for 1.5 minutes (without benefit of pre-heating the mixture) to form an effective adhesion between the core adhesive-based laminate and 2 12-micron thick BOPET blown film sheets covered on one side with 0.5 m vapor deposited aluminum on each side, glued to the core adhesive-based laminate, resulting in a strong bond between all laminates yielding a strong laminated composite. Other combinations of oat hulls, Platamid adhesive, CaCO3, with and without a micro thin spray of 3MSuper77 adhesive, and in one case 1% Fusabond all created strong bonds between laminates. All were pressed and heated as described above and cooled on the lab floor. Many combinations of the formula are possible in creating an optimized series of film products with high percentage of oat hulls.

[0046] The described embodiments are preferred and/or illustrated, but are not limiting. Various modifications are considered within the purview and scope of the appended claims.