BR112017026181B1 - CARDBOARD PACKAGING MATERIAL - Google Patents

Abstract

WOODLESS FIBER COMPOSITIONS AND USES IN CARDBOARD PACKAGING. A cardboard packaging material includes a topsheet including non-wood fibers blended with wood fibers, wherein the non-wood fibers are 5% to 100% of the topsheet; a backing layer including non-wood fibers blended with wood fibers, wherein the non-wood fibers are 5% to 100% of the backing layer; and an intermediate layer disposed between the top and back layers. The intermediate layer may include 5% to 100% non-wood filler fibers. The non-wood filler fibers may be wheat straw. Non-wood fibers can be bamboo.

Description

FUNDAMENTALS

[01] The present disclosure relates to the use of alternative natural non-wood fibers in corrugated media for cardboard packaging. A replacement for conventional hardwood fiber is achieved through a hybrid fibrous composition that provides sufficient mechanical strength for carton packaging applications.

[02] Traditionally, pulp derived from fast-growing trees, such as pine, has been used as a raw material for cardboard packaging. In recent years, the use of recycled corrugated old cardboard (OCC) material has grown in popularity due to environmental sustainability concerns. However, OCC often requires repulping and de-inking processes. As such, recycled fibers are shortened, weakened and contaminated as the amount of recycling increases. Along with an increase in demand and the use of recycled fibers by many producers, the cost of recycled fiber has also increased. The move towards single stream recycling is causing an increase in contamination (staples, plastic tapes and hot applied adhesives) from blending the fibers in existing recovered fiber streams. Critical performance requirements such as strength (compression, edge crushing, break and tensile strength), hardness, stiffness, moisture resistance, grease resistance, and freeze/thaw tolerance may be more difficult to achieve with paper or paperboard. recycled.

[03] Unbleached Solid Sulfate (SUS) or Bleached Solid Sulfate (SBS) are premium board grades that are produced from a base piece containing at least 80 percent long and short bleached wood pulp. The most discolored cardboard is coated with a thin layer of kaolin clay to improve the smoothness of the surface for printing. SBS is most popular in the United States. Unfortunately, the supply of NBSK (Northern Bleached Softwood Kraft) as a softwood is under significant pressure, both economically and environmentally. As such, the cost of NBSK fiber has increased significantly, creating a need to find alternatives to optimize the strength of cardboard.

[04] These approaches rely on tree-based fibers. The ability to use fibrous feedstock that grows in a shorter life cycle and use waste from agricultural or industrial processing can help meet corporate sustainability goals and reduce the environmental impact on forests as well as the carbon footprint (measurement in eCO2 units).

[05] Pulping processes for natural non-wood fibers are raw material dependent and detailed steps can be found in Sridach, W. (2010), The Environmentally Benign Pulping Process of Nonwood Fibers, Suranaree J. Sci. Technol., 17(2), 105-123 and in US Patent 6,302,997 B1 to Hurter and Byrd. Alternative non-wood natural fibers, such as using fibers from field crops or agricultural residues, instead of wood fibers, are considered to be more sustainable. Examples of such natural raw materials are kenaf, flax, bamboo, cotton, jute, hemp, sisal, sugarcane bagasse, corn husk, rice straw, wheat straw, hesperaloe, yellow millet, rush, arundo donax, water algae fresh or marine or aquatic plants such as water hyacinth. Non-wood fiber sources only account for about 5-10% of global pulp production, for a variety of reasons including seasonal availability, issues with chemical recovery, pulp brightness, silica content, etc. However, they provide an option that any product manufacturer can explore to add a green component to their end products.

[06] Hybrid fiber compositions, including alternative natural non-wood fibers such as those derived from seaweed, seaweed, corn husk, wheat straw, rice straw, bamboo, kenaf and the like, may be an option. to resolve these aforementioned issues by creating wood-free products.

[07] CN 2099771 U describes a corrugated box containing 100% non-wood fibers on the surface, bottom and core layers.

[08] US 2010/003431 A1 describes composite materials with favorable properties, which include a filler-containing layer and a fiber-containing layer substantially continuously coupled across at least one surface of the layers.

[09] WO 2014/049476 A1 describes a cardboard packaging material which is the corrugated medium (i.e. the intermediate layer) for cardboard packaging and which comprises at least one alternative non-wood cellulose material in the amount from 5 to 100%.

[10] US 2006/003119 A1 describes a food container which is a compression molded article of a composition comprising an unboiled bamboo fiber mixed with an unboiled mixture of plant fibers from grasses (except bamboo fibers) and vegetable fibers from legumes, such as Lespedeza fibers. The composition may further contain notable amounts of a water-repellent and paper-strengthening agent to form a mixture from which the container is molded.

[11] The previous approach (see US Patent No. 1,829,852 for Darling) used chopped wheat straw (not a fiber per se) to make cardboard. In another approach (see US Patent Publication No. 2006/0070295 for Huang and Peng) described a non-wood fiber straw mat (corn or wheat) for weed control in agricultural crops and cultivation. Finally, chitosan in addition to agricultural waste fibers was used to improve the flat crush strength of a corrugated medium (see US Patent No. 4,102,738 for Dzurik).

[12] Therefore, there is a need to provide alternative pulp materials to wood to replace the conventional fiber materials used in cardboard packaging. Additionally, there is a growing need for lighter weight and stronger corrugated materials that allow for reduced package weight. Despite previous attempts to use alternative fibers to produce composite board applied to construction and furniture, there is a lack of sustainable attempts to produce corrugated media based on non-wood natural fiber for use in cardboard packaging applications. As a result, the present disclosure fills these gaps by providing alternative materials to wood that can be used for environmentally sustainable cardboard packaging.

SUMMARY

[13] The present disclosure is directed to a cardboard packaging material including a topsheet including non-wood fibers blended with wood fibers, wherein the non-wood fibers are 5% to 100% of the topsheet; a backing layer including non-wood fibers blended with wood fibers, wherein the non-wood fibers are 5% to 100% of the backing layer; and an intermediate layer disposed between the top and back layers. The intermediate layer may include 5% to 100% non-wood filler fibers. Non-wood filler fibers can be selected from corn husk, straw, other natural terrestrial fibers and combinations thereof. Straw may be selected from the group consisting of wheat, rice, oats, barley, rye, flax and grass and combinations thereof. The other natural terrestrial fibers are selected from flax, bamboo, cotton, jute, hemp, sisal, bagasse, kenaf, hesperaloe, yellow millet, miscanthus and combinations thereof. The non-wood filler fibers may be wheat straw. Non-wood fibers can be bamboo.

[14] The present disclosure is also directed to a cardboard packaging material including a top layer that includes non-wood fibers mixed with wood fibers, wherein the non-wood fibers are 50% to 85% of the layer. upper, where the non-wood fibers are bamboo; a backsheet including non-wood fibers blended with wood fibers, wherein the non-wood fibers are 50% to 85% of the backsheet, wherein the non-wood fibers are bamboo; and an intermediate layer disposed between the top and back layers.

[15] The present disclosure is also directed to a cardboard packaging material including a top layer that includes non-wood fibers mixed with wood fibers, wherein the non-wood fibers are 50% to 85% of the layer. upper, where the non-wood fibers are bamboo; a backsheet including non-wood fibers blended with wood fibers, wherein the non-wood fibers are 50% to 85% of the backsheet, wherein the non-wood fibers are bamboo; and an intermediate layer disposed between the top and back layers, wherein the intermediate layer includes from 5% to 100% non-wood filler fibers. BRIEF DESCRIPTION OF THE FIGURES

[16] The foregoing and other features and aspects of the present disclosure and the manner of obtaining them will become more apparent, and the disclosure itself will be better understood by reference to the following description, appended claims, and accompanying figures, where: 1 shows a schematic illustration of a typical cardboard structure; Figure 2 shows a sectional view of the cardboard in micrograph by the Broad Ion Beam technique (150X); and Figure 3 shows a sectional view of the cardboard in SEM C-Stain micrograph of the cardboard of the present application.

[17] The repeated use of reference characters in this specification and figures is intended to represent the same or analogous features or elements of the present disclosure. Figures are representative and not necessarily drawn to scale. Certain proportions of these figures may be exaggerated, while others may be minimized.

DETAILED DESCRIPTION

[18] While the specification concludes with the claims particularly pointing out and distinctly claiming the disclosure, it is believed that the present disclosure will be better understood from the following description.

[19] As used here, “comprising” means that other steps and other ingredients that do not affect the end result can be added. This term encompasses the terms “consisting of” and “consisting essentially of”. The compositions and methods/processes of the present disclosure may comprise, consist of, and essentially consist of the essential elements and limitations of the disclosure described herein, as well as any of the additional or optional ingredients, components, steps, or limitations described herein.

[20] As used here, the term “non-wood based” or “wood alternative” generally refers to crop processing residues such as wheat straw, wetland plants excluding trees such as reeds, aquatic plants such as water hyacinth, microalgae such as Spirulina and macroalgae such as red or brown algae. Examples of natural non-wood-derived materials of the present invention include, but are not limited to, wheat straw, rice straw, flax, kenaf, bamboo, cotton, jute, hemp, sisal, bagasse, Hesperaloe, yellow millet, miscanthus, marine or freshwater algae and their combinations.

[21] As used here, the term “OCC” refers to old corrugated cardboard containers that have layers of paper glued together in an inner fluted layer. This is the material used to make corrugated cardboard boxes (the most recycled product in the country). Four main components of OCC pulps are unbleached softwood kraft pulp (derived primarily from cladding board), semi-chemical hardwood pulp (derived from fluted medium), starch (as an adhesive), and water (often 8% or most).

[22] As used herein, the term "pulp" or "pulp fiber" refers to fibrous material obtained by conventional pulping processes known in the art. This can be for wood-based and non-wood-based materials.

[23] As used here, the term “fines” refers to the fraction that passes through a 200 mesh (75 μm) sieve. The average fine size is a few microns. The fines consist of cellulose, hemicellulose, lignin and extractives. There are two types of fines: primary fines and secondary fines. The content of primary fines appears to be a genetic trait of the plant. For hardwood pulp it is about 20% to about 40%, while for wheat straw it is about 38% to about 50%. Secondary fines are pieces of fibrils from the outer layers of the fibers that are broken down during refinement.

[24] As used here, the term “weight” generally refers to the dry weight per unit area of a carton. Weight is measured here using the TAPPI test method T-220. A sheet of pulp, usually 30 cm x 30 cm or another convenient size, is weighed and then oven dried to determine the solids content. The sheet area is then determined and the ratio of oven dry weight to sheet area is reported as dry weight in grams per square meter (g/m2).

[25] As used herein, the term “Tensile Strength Index” is expressed in Nm/g and refers to the quotient of tensile strength, usually expressed in Newton-meters (N/m) divided by grammage.

[26] As used herein, the term “Rupture Index” refers to the breaking strength quotient, usually expressed in kilopascals (kPa) divided by grammage, usually expressed in grams per square meter (g/m2).

[27] As used here, the term “ring crush” refers to the strength of paper and cardboard to edge compression, usually expressed in kilonewtons per meter (kN/m).

[28] As used here, the term “compression” refers to the ability of shipping containers to resist external compressive forces, which is related to the stacking force of containers being subjected to forces encountered during transport and storage. . Usually expressed in Newton (N).

[29] As used here, the term “edge crushing” refers to the lateral compressive strength, usually expressed in kilonewtons per meter (kN/m).

[30] As used herein the term "fabric forming apparatus" generally includes a fourdrinier former, twin yarn former, roller machine, press former, crescent former and the like known to those skilled in the art.

[31] As used herein the term “Canadian standard freeness” (CSF) generally refers to the rate at which the fiber slurry is drained and is measured as described in the TAPPI test standard, method T 227 OM- 09. The unit of CSF is mL.

[32] Fig. 1 schematically shows a cardboard structure of the present invention, where the middle layer 10 uses BCTMP and the top and back layers 20, 30 use NBKP and LBKP. In this example, calcium carbonate is used for the coating of cardboard 40. The coating materials applied to the top layer 20 are three times higher than those applied to the back layer 30.

[33] The invention describes the use of bamboo to replace a part of the virgin long wood fiber in the top and back layers 20, 30. Optionally, the intermediate layer 10 can also be replaced with another alternative non-wood fiber such as straw. wheat.

[34] Bamboo can be used to replace some of the virgin long wood fiber in the top and back layers 20, 30 of a multi-layer premium cardboard structure. The examples described below range from 50 to 85% bamboo in one layer. Optionally, the intermediate layer 10 can also be replaced with another alternative non-wood fiber such as wheat straw. Examples described below include 100% wheat straw. Mechanical properties are comparable or better than the control which is composed of all virgin cellulose fibers. Cardboard can be used for product packaging in support of sustainability goals, at a cost equivalent to or possibly less than current wood-based cardboard.

[35] As mentioned above, SUS/SBS board is made from virgin wood-based fibers today. However, the continued uses of softwood fiber are economically and environmentally challenged. Therefore, a wood-based softwood replacement meets unsatisfied commercial needs. Natural long non-wood fibers selected from bamboo species are not commonly used in the top and back layers 20, 30 of the cardboard. This disclosure describes the use of bamboo in cardboard, which was previously unknown and not practised. The bamboo-containing cardboard sheet can then be coated for printing and converting.

Os dois documentos a seguir descrevem o uso de fibras alternativas de não- madeira em papelão (papelão ondulado): US2014093705 Composições de fibra livre de base em madeira e usos em embalagem de papelão US2014093704 Composições de fibra híbrida e usos em embalagens de papelão

[36] A conventional SUS/SBS cardboard structure is layered. The top and back layers 20, 30 use a blend of softwood and hardwood short fibers. The intermediate layer 10 uses bleached or unbleached chemothermomechanical pulp (CTMP). Typically, a coating is applied to external surfaces, such as latex, kaolin clay, or calcium carbonate. Using alternative non-wood natural fibers such as bamboo is an option to replace NBKP (top and back layers 20, 30) in cardboard to create new packaging materials. This disclosure relates to multi-ply paper and board products, wherein the top and back layers are formed using bamboo, or a combination of bleached bamboo sheet kraft pulp (LBKP) and NBKP fibers. The effectiveness of such an application is an unexpected result - that the use of bamboo to replace virgin wood fibers provides superior mechanical properties compared to a control that is composed of all virgin wood cellulose fibers. The data shown in this disclosure demonstrates the ability to use alternative fibers for product packaging. The following two documents describe the use of bamboo in fabric products: US8778505 Bamboo Composite Fabric Product US8524374 Bamboo Composite Fabric Product

The following two documents describe the use of alternative non-wood fibers in cardboard (corrugated cardboard): US2014093705 Free-based fiber compositions in wood and uses in cardboard packaging US2014093704 Hybrid fiber compositions and uses in cardboard packaging

[37] A major issue affecting the pulp and paper industries worldwide is the rising cost of suitable wood fiber resulting from concerns regarding competing uses for forest lands, environmental impact of forest operations and sustainable forest management. In recent years, leading fabric manufacturers have been motivated to examine the alternative use of natural non-wood fibers for product manufacturing due to sustainability issues related to commodity pulp. Reducing reliance on commodity wood pulp can also alleviate pressure from NGOs and consumers who prefer to use green products. Use of recycled fibers, however, in a variety of products is technically limited by the quality of the final product acceptable to users.

[38] Recycled fibers can be derived from any paper and board that has been collected for reuse as a paper fiber feedstock and in board manufacturing. On the other hand, commodity wood pulps are classified as pulp derived from softwood from soft trees such as spruce, pine, spruce, larch and hemlock, and pulp derived from hardwood such as eucalyptus, aspen and birch derived. of hardwood trees such as eucalyptus, poplar and birch.

[39] Pulping processes for natural non-wood fibers are raw material dependent; detailed steps can be found in Sridach, W. (2010), The Environmentally Benign Pulping Process of Nonwood Fibers, Suranaree J. Sci. Technol., 17(2), 105-123. For example, red algae pulp can be processed through simple bleaching steps with much less energy and cost, partially due to the fact that there is no lignin present (Seo, Y.B. et al. (2010), Red Algae and Their Use in Papermaking, Bioresource Technology, 101, 2549-2553).

[40] The use of alternative natural non-wood fibers such as using crop fibers and agricultural residues instead of wood fibers is considered more sustainable, due in part to the classification of these materials as by-products or waste from other processes. Suppliers can pay customers to help eliminate these materials. Examples of such natural raw materials are kenaf, flax, bamboo, cotton, jute, hemp, sisal, sugarcane bagasse, corn husk, rice straw, wheat straw, hesperaloe, yellow millet, rush, arundo donax, water algae fresh or marine or aquatic plants such as water hyacinth. Non-wood fiber sources only account for about 5-10% of global pulp production for a variety of reasons including seasonal availability, issues with chemical recovery, pulp brightness, silica content, etc.

[41] The present disclosure describes the use of at least one alternative non-wood or wood-free pulp material in carton packaging to replace a large portion of conventional fiber materials, particularly in the middle layer. The composition of the present disclosure includes at least one non-wood alternative pulp material selected from algae, such as red algae, corn husk, straw, other natural terrestrial fibers and combinations thereof. The other terrestrial natural fibers may include flax, bamboo, cotton, jute, hemp, sisal, bagasse, kenaf, hesperaloe, yellow millet, miscanthus and combinations thereof. The individual fibrous material from non-wood materials can be derived from conventional pulping processes such as mechanical thermal pulping, Kraft pulping, chemical pulping, enzyme-assisted biological pulping or organosolvent pulping known in the art.

[42] The pulp material compositions of the present invention may include various amounts of non-wood alternative natural pulp fibers. The composition may have a combination of elements, wherein there is at least one non-wood alternative natural pulp fiber alone, or it may be combined with a wood-based pulp fiber. For example, the amount of alternative non-wood natural pulp fibers of the present invention may be present in an amount of about 5%, about 10%, about 20%, about 25%, about from 30% to about 40%, to about 50%, to about 60%, to about 75%, to about 100% by weight of the composition. The pulp material compositions of the present invention may also comprise a hardwood hardwood hardwood pulp in an amount of about 5%, about 10%, about 20%, or about 30%, to about from 40%, to about 50%, to about 60%, or to about 70%, by weight of the composition. When the alternative non-wood pulp materials are not present alone, in combination with each other, or in combination with a wood pulp fiber, the composition can then be used for a carton package that replaces a portion of the materials. conventional fiber.

[43] The compositions of the present invention may show combinations, although not limited to, in which the ratio of chemical hardwood pulp: alternative natural non-wood pulp may be from about 70:30, from about 60: 40, about 50:50, about 30:70, about 5:95, or about 0:100. In any of the alternative natural non-wood pulps there may be the use of one, two or more types of alternative natural non-wood pulp in combination.

EXAMPLES

[44] The following examples further describe and demonstrate aspects within the scope of the present disclosure. The examples are given for illustrative purposes only and should not be construed as limiting the present invention, as many variations thereof are possible. The results indicate that the corrugated medium can be made based on fiber from non-wood alternatives such as kenaf fiber, wheat straw, miscanthus, corn husk, bamboo and red algae. This disclosure is about non-wood based cardboard, which is a significant contrast to current practices that rely on OCC, hardwood pulp, or a combination of both. Overview

[45] Two sets of sample paper samples were made. Example 1 as a control sample and example 2 as an inventive sample were done on a dynamic sheet former (available from Fibertech, Sweden). Example 2 includes 50% bamboo in the top and back layers 20, 30 and replaces the middle layer 10 with wheat straw.

[46] The layer structure/content of example 1 (control) is 1:1:1 (Pine)/(Pre-consumer fiber)/(Pine), where Alabama pine is GP Cellulose and pre-consumer fiber. recycled consumer is Fox River Fiber (brightness >82.9% and freeness >482 mL).

[47] The layer structure/content of example 2 is 1:1:1 (50/50 Pine/Bamboo)/(Wheat Straw)/(50/50 Pine/Bamboo)

[48] Observed benefits: All mechanical properties are comparable or better than the control of Example 1. Example 2 demonstrated improved mechanical strength, including tensile and ZD stiffness. This is surprising, as the presence of alternative non-wood fibers typically negatively affects the mechanical properties of a composite board.

[49] Example 3 as a control sample and example 4 as an inventive sample were made on a commercial paper machine (IP-Sun, Yanzhou, Shandong, China). Example 4 includes 75% bamboo in the top layer 20 and 85% in the back layer.

[50] Example 3 (control) is commercially available as StarBlanc C1S Ivory Board. Its layer structure is approximately 1:4:1 (mixing of two types of Kraft Pulp NBKP/LBKP)/(mixing of two types of Mechanical Pulp APMP/BCTMP and breaking)/(mixing of two types of Kraft Pulp NBKP /LBKP). It is coated on both sides. See below for specific details.

[51] The layer structure of example 4 is approximately 1:4:1 (25/75 NBKP/Bamboo)/(same middle layer as in example 3)/(15/85 NBKP/Bamboo). It is also similarly coated on both sides.

[52] Observed benefits: All mechanical properties are comparable or better than the control of example 3. The bending strength of example 4 is much better than that of the control of example 3. The softness of example 4 is less than half that of control sample value, but still much higher than the required level.

materials

[53] Bamboo pulp was purchased from Xiamen C&D Paper&Pulp Co., Ltd. in Xiamen, China. Northern Bleached Kraft Pulp (NBKP) is made from softwood fibers such as those that are pulped from Masson pine, larch, pine and spruce. Bleached Leaf Kraft Pulp (LBKP) is made from hardwood fibers such as pulped birch, poplar, linden, maple and eucalyptus. These materials were purchased from UPM Uruguay in Helsinki, Finland. BCTMP SW pulp was purchased from Panpac Forest Products, Ltd. in Napier, New Zealand. Alkaline peroxide mechanical pulp (APMP) was purchased from Yanzhou Heli Paper Industry Co., Ltd. in Yanzhou, China. The breakage is recycled from the manufacturing processes. Latex, clay and ground calcium carbonate were used as coating materials for cardboard manufacturing.

[54] Pre-consumer recycled fiber (Fox River Fiber, De Pere, WI), wheat straw (Shandong Pulp and Paper Co. Ltd., Jinan, China) and Alabama pine (GP Cellulose, Atlanta, GA) ) were used to make three-layer paper samples using a dynamic paper sampler. Equipment

[55] The inventive samples were made using a paper machine (PM 18) at IP-Sun, in Yanzhou, Shandong, China. A trimmed cardboard width is 3350 mm. The PM 18 was equipped with four threads (Top Fold, Bottom Fold, Fill Fold and Back Fold).

[56] A sheet of layered paper was formed using a dynamic sheet former (Fibertech, Sweden) by pumping the paper (pulp consistency of 0.5% or less) from the mixing box through a transition nozzle to the rotating drum (1450 rpm) on blotting paper on top of a 100 mesh metal screen, draining the paper to form the sheet, pressing (20 PSI) and dyeing the sheet at 150 oC. The amount of fiber for each layer and additives (if used) can be controlled in the mixing box, before pumping.

Example 1

[57] This control cardboard sample contains 1/3 of the top layer 20 (pine) and 1/3 of filler in the middle (pre-consumer fiber) and 1/3 of the back layer 30 (pine), respectively. It was formed using the dynamic sheet former. The fiber weight for each layer was determined according to the target board weight of 60 pounds per 1000 square feet (~300 g/m2) and a dilute slurry (0.5% or less) was prepared in the mixing box and pumped through the pass-through nozzle onto the blotting paper in the rotating drum. The formed wet cardboard was pressed and dried at 150 °C for about 10 minutes. The test results are shown in Table 1, which can be used to compare them against the sample in example 2.

Example 2

[58] As shown in Table 1, the sample of example 2 was made using different combinations of pine and bamboo fibers for the top and back layers 20, 30. However, the middle layer 10 was completely replaced by wheat straw. The paper sample weight and base size for example 2 are the same as for example 1, but the caliper is greater than a directed value of 16 points.

[59] Paper samples were conditioned at temperature (23±1 oC) and humidity (50±2%) at least overnight and tested for caliper (TAPPI T411), weight (TAPPI T410), tensile (TAPPI T220), ZDT tension (TAPPI T541), ring crush (T818), Mullen pull (TAPPI T807) and STFI (T826). At least three replicates (n=3) were tested to produce the mean values reported for each parameter. All mechanical properties are comparable or better than those of the sample shown for example 1. It is surprising, in particular, that the 100% wheat straw in the intermediate layer 10 showed improved mechanical strength, such as ZD tensile and stiffness. Stiffness is the most important parameter for cardboard as it affects the ability of boxes to run smoothly through the machine that lifts, fills and closes them. Typically, the presence of alternative non-wood fibers will adversely affect the mechanical properties of composite board. Table 1 Mechanical Properties of Three-Layer Paper Samples

Example 3

[60] This example uses a commercial cardboard sample, StarBlanc C1S Ivory board, as a control sample. It has the same multilayer composition as described in Fig. 1. However, all fibers used in the control sample are virgin wood pulp, where the intermediate layer 10 is made of 35% APMP, 30% BCTMP and 35% breakage. The top and back layers 20, 30 are 15 to 25% NBKP and 75 to 85% LBKP. There are three layers of coating on the front side of the cardboard and one layer of coating on the reverse side. The grammage is directed to 300 g/m2. The weight distribution is about 58-65% for the middle layer 10, 14-15% for the top layer 20 and 11-12% for the back layer. The rest are coating layers. Control cardboard test parameters are listed in Table 2.

Examples 4

[61] Bamboo pulp was used in this example to replace a portion of virgin wood pulp in the top and back layers 20, 30. The top layer 20 used 25% NBKP and 75% bamboo. Back layer 30 used 15% NBKP and 85% bamboo. Cardboard made from PM 18 was tested under controlled temperature (23±1 oC) and relative humidity (50±2%). The results are shown in Table 2. Compared to the control sample, the bending strength is much better than for the control sample, while the smoothness is about Yz of the control. Softness required is at least 100 or in a range of 150 and above.

[62] These fiber proportions can be changed and however are still within the scope of the invention. For example, top layer 20 can use 50% bamboo and 50% LBKP. Alternatively, the back layer 30 can use 30% bamboo and 70% LBKP, keeping the middle layer 10 the same. Table 2 Control and Sample Cardboard Test Results

Example 5

[63] The cardboard sample from Example 4 was assembled and cut into a wide ion beam (BIB) section for a cross-sectional view at the MVA Scientific Consultant (Duluth, GA). BIB cross-section is an advanced method for preparing accurate cross-sectional surfaces for a wide variety of materials. BIB excels compared to traditional methods, such as mechanical or microtome polishing, when cutting flexible materials, very hard materials, porous materials, or combinations of these in cross section. The surface area in cross-section BIB is approximately 1 mm wide and several hundred micrometers long. The ion beam is able to cut the cardboard without deforming it, or filling the pores. This allows for detailed studies of the pore structure, for example how deep filler material such as calcium carbonate will penetrate the porous coating layer.

[64] A sample is first cut and trimmed to the proper size and shape. It is then fixed to a sample holder (titanium) which acts as a masking plate. A small part (20-200 μm) of the sample is left visible above the edge of the mask. The wide argon ion beam is aligned perpendicularly to the edge of the mask, so that half of the beam hits the sample and the other half hits the mask. The ions begin to remove material from the visible area of the sample, while the masking plate protects the rest. Over time, ion bombardment results in a clean, flat cross-sectional area of the sample behind the edge of the masking plate. As shown in Fig. 2, the thick white layer is a three-layer calcium carbonate coating, and the thin layer is a one-layer calcium carbonate coating. The fiber of the BCTMP part is layered in the middle and hollow. The top and back layers 20, 30 are a blend of wood and bamboo based fibers. These observations are further verified in Fig. 3, where SEM C-stain shows lignified BCTMP (yellow color) in the medium wood and bamboo-based fibers and misaligned in the top and back layers 20, 30. Furthermore, it is visible that the density of the fibers changes throughout the thickness. of cardboard.

[65] All percentages, parts and ratios are based on the total weight of the compositions of the present disclosure unless otherwise specified. All these weights, insofar as they pertain to the ingredients listed, are based on the active level and therefore do not include solvents or by-products that may be included in commercially available materials unless otherwise specified. The term “percent by weight” can be symbolized by “% by weight” here. Except where specific examples of actual measured values are given, numerical values referred to herein should be considered to be qualified by the word “fence”.

[66] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values quoted. Instead, unless otherwise specified, each dimension is intended to mean the quoted value and a functionally equivalent range around that value. For example, a dimension disclosed as "40mm" is intended to mean "about 40mm".

[67] All documents cited in the Detailed Description are, in relevant part, incorporated herein by reference; citation of any document should not be construed as an admission that it is the state of the art with respect to the present disclosure. To the extent that any meaning or definition of a term written herein conflicts with any meaning or definition of the term in a document incorporated by reference, the meaning or definition given to the term written herein will control.

[68] While specific embodiments of the present disclosure have been illustrated and described, it will be obvious to those skilled in the art that various other changes and modifications may be made without departing from the spirit and scope of the disclosure. It is therefore intended to encompass, in the appended claims, all such changes and modifications that are within the scope of this disclosure.

Claims (14)

1. Cardboard packaging material, characterized in that it comprises: a top layer (20) including non-wood fibers mixed with wood fibers, wherein the non-wood fibers are 50% to 85% of the top layer (20); a backsheet (30) including non-wood fibers blended with wood fibers, wherein the non-wood fibers are 50% to 85% of the backsheet (30); and an intermediate layer (10) disposed between the top (20) and back (30) layers. 2. Cardboard packaging material according to claim 1, characterized in that the intermediate layer (10) includes 5% to 100% non-wood filling fibers. 3. Cardboard packaging material according to claim 2, characterized in that the non-wood filler fibers are selected from corn husk, straw, other earth-based natural fibers and combinations thereof. 4. Cardboard packaging material according to claim 3, characterized in that the straw is selected from the group consisting of wheat, rice, oats, barley, rye, flax, grass and combinations thereof. 5. Cardboard packaging material, according to claim 3, characterized in that the other natural terrestrial fibers are selected from flax, bamboo, cotton, jute, hemp, sisal, bagasse, kenaf, hesperaloe, yellow millet, miscanthus and combinations thereof. 6. Cardboard packaging material, according to claim 2, characterized in that the non-wood filling fibers are wheat straw. 7. Cardboard packaging material, according to claim 1, characterized in that the non-wood fibers are bamboo. 8. Cardboard packaging material, according to claim 1, characterized in that it further comprises a coating on one or both of the upper (20) and back (30) layers. 9. Cardboard packaging material, according to claim 8, characterized in that the coating is selected from latex, kaolin clay and calcium carbonate. 10. Cardboard packaging material, according to claim 1, characterized in that the intermediate layer (10) includes 5% to 100% non-wood filling fibers. 11. Cardboard packaging material according to claim 10, characterized in that the non-wood filler fibers are selected from corn husk, straw, other earth-based natural fibers and combinations thereof. 12. Cardboard packaging material, according to claim 11, characterized in that the straw is selected from the group consisting of wheat, rice, oats, barley, rye, flax, grass and combinations thereof. 13. Cardboard packaging material, according to claim 11, characterized in that the other natural terrestrial fibers are selected from flax, bamboo, cotton, jute, hemp, sisal, bagasse, kenaf, hesperaloe, yellow millet, miscanthus and combinations thereof. 14. Cardboard packaging material, according to claim 1 or 10, characterized in that the non-wood filling fibers are wheat straw.

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