Patent Application
20230295873
The present invention is directed to compositions, in particular pulp compositions, comprising agricultural plant fibres and wood fibres, wherein the wood fibres may be recycled wood fibres. The present invention is also directed to methods of making these compositions, paperboard or paper comprising or obtained from these compositions, the use of these compositions in making paperboard, paper or packaging, and packaging comprising or prepared from the compositions of the present invention.
Pulp and paperboard/paper production based on wood fibre is a highly resource intensive and polluting industry. The vast majority of pulp for paperboard/paper making is prepared from a combination of both softwood and hardwood fibres, which can be virgin fibres or recycled fibres. Fibres originating from woodlands and tree plantations have a devastating impact on the environment in various ways, such as a loss of biodiversity and biomass above and below ground biota (which is one of Earth's main CO2 sinks), soil erosion, floods and climate change. Also, the processing of turning wood into virgin fibers has an additional negative impact on CO2 emissions because roughly 80% of the CO2 stored in trees ends up being released in the waste stream and consumption of wood (e.g., burning of wood, production of paper or other products).
Besides wood fibre, the primary inputs into the paperboard and paper making process are water, energy and chemicals. The energy cost of paperboard and paper production represents 10-40% of total manufacturing cost and is an important factor influencing profitability of a mill operation. Manufacturing pulp and paperboard/paper requires a substantial amount of water since it is used in all major process stages. The benchmark for water usage within pulp and mills ranges between 64,352 and 113,562 liters/ton of paperboard/paper. Within the pulping process, most methods use sulfur and chlorine compounds to increase pulp quality and yield, resulting in NOx and SOx emissions such as dimethyl sulfide (DMS), dimethyl disulfide (DMDS), and methyl mercaptan. Aside from odor nuisance in the mills and surroundings, oxidized sulphur contributes to the large-scale acidification of soil, which negatively affects vegetation and biodiversity. Although methods to control chemical balance are applied, many modern mills still have difficulties controlling sulfidity.
Meanwhile, alternative, non-wood fibres from agricultural sources can deliver fibres of suitable quality for the production of paperboard and paper. Barley is one of the four main ingredients in beer, along with water, yeast and hops. Wheat is also commonly used in beer production. However, only the grains of the barley and wheat plants are used in the brewing process. After the barley or wheat is harvested, there is an abundance of straw leftover as a by-product, which has a high fibre content. Making use of the straw fibres creates value from a by-product which is often left to decay, burnt, or sold as low value animal bedding. These straw fibres have been shown to be suitable for pulp and paper production (see, for example, WO 99/18285 A1). However, the resulting paper often does not have the physical and mechanical properties (such as tensile strength and tear strength) needed for secondary packaging such as packaging for beer bottles or cans, which requires the package to carry relatively high weight and where liquid from condensation or spillages can affect the integrity of the packaging.
In view of the above, there is a need in the art for compositions derived from alternative raw materials for use in making paperboard, paper and packaging in order to reduce the environmental impact of production. There is also a need for paperboard and paper derived from alternative raw materials that has improved physical and mechanical properties. Additionally, many alternative fibres are not able to withstand the high pressure, temperature and intensive mechanical processing used for processing wood fibres to make paperboard or paper. Accordingly, methods of producing paperboard and paper from alternative raw materials that have reduced water and energy consumption and reduced use of chemicals are needed.
In a first aspect, the present invention is directed to composition, preferably a pulp composition comprising:
In a second aspect, the present invention is directed to a method of making a composition of the present invention, comprising the step of: mixing a first component comprising agricultural plant fibres and a second component comprising wood fibres.
In a third aspect, the present invention is directed to paperboard or paper comprising the composition of the present invention.
In a fourth aspect, the present invention is directed to paperboard or paper prepared from the composition of the present invention.
In a fifth aspect, the present invention is directed to use of a composition as defined herein in the manufacture of paperboard, paper or packaging.
In a sixth aspect, the present invention is directed to a method of preparing paperboard, paper or packaging comprising:
In a seventh aspect, the present invention is directed to packaging comprising the composition of the present invention.
In an eighth aspect, the present invention is directed to packaging prepared from the composition of the present invention.
Agricultural plant fibres: Agricultural plants include all non-wood plants, such as cereal plants. Agricultural plant fibres may be from or derived any part of the non-wood plant, such as the stem, bark or skin, leaves or fruit. Preferably the fibres are derived from the stem or stalk, which may be known as straw.
Recycled wood fibres: Recycled wood fibres are non-virgin wood fibres. Recycled wood fibres are divided into a number of grades depending on the origin of the wood fibres and their relative contents. Recycled paper grades are defined by, for example, the Confederation of European Paper Industries' (Cepi) EN 643 standard.
Group 1 according to EN 643 (Ordinary Grades) includes, corrugated paper and board wastes, Old Corrugated Containers (OCC) and Unsold Magazines. Corrugated paper and board wastes may contain used paper and board packaging that may be made up of a minimum of 80% of corrugated board, the rest being other paper and board products.
Old Corrugated Containers (OCC) may comprise used boxes and sheets of corrugated board of various qualities and 10% of other packaging papers and boards. OCC may alternatively comprise used boxes and sheets of corrugated board of various qualities and 5% of other packaging papers and boards. Group 2 according to EN 643 (Medium Grades) includes, for example, unsold newspapers, sorted office paper and white wood-free books. Group 3 according to EN 643 (High Grades) includes, for example, wood-free binders, white wood-free letters, white heavily printed multiply board, and white woodfree shavings. Group 4 according to EN 643 (Kraft Grades) includes, for example, unused corrugated material, used/unused kraft sacks with polycoated papers. Group 5 according to EN 643 (Special Grades) includes, for example, mixed recovered paper and board, liquid board packaging, and labels.
Softwood fibres: Softwood fibres are virgin wood fibres and may comprise any softwood fibres known in the art, for example fibres from pine, spruce and/or coniferous trees.
Hardwood fibres: Hardwood fibres are virgin wood fibres and may comprise any hardwood fibres known in the art, for example, fibres from aspen, birch and/or eucalyptus trees.
Paperboard: Paperboard refers to a paper-based material that comprise fibres from sources such as agricultural plants and wood, Typically, paperboard is thicker than paper. Paperboard includes but is not limited to material such as card, cardboard, folding boxboard, cartonboard, folding carton, containerboard and linerboard. Generally, paperboard has a grammage above 250 g/m2.
Paper: Paper refers to material that comprises fibres from sources such as agricultural plants and wood. Generally, paper has a grammage below 250 g/m2.
Fibre dimensions: Various fibre dimensions are recited herein, e.g. fibre length, fibre width. Wherever such dimensions are given, the values recited are average values. Preferably the values relate to dry fibres.
The Compositions of the Present Invention
Most paperboard or paper is a mixture of hardwood and softwood fibres, each giving different characteristics. Agricultural plant stalk fibres from, for example, barley and wheat have physical characteristics that fall between hardwood and softwood and are superior to recycled wood fibre. Other advantageous characteristics of pulps made from agricultural plant fibres; in particular cereal plant fibres, especially barley & wheat, include:
The present invention uses these advantageous properties in its compositions for the production of high-quality paperboard and paper.
In addition to the above, most available pulping processes tend to reduce the fibre length. The agricultural plant fibres (e.g. cereal fibres) present in the compositions of the invention typically have a longer fibre length than those produced in conventional pulping processes. Preferably the agricultural plants fibres (e.g. cereal fibres) are prepared in a pulping process that uses milder conditions to preserve fibre length. This ensures the pulp quality is high, and leads to improved mechanical performance and durability of the end product.
In one aspect, the present invention is directed to a composition, preferably a pulp composition, for making paperboard or paper comprising:
The agricultural plant from which the fibres are derived may be, for example, one or more selected from the group consisting of barley, wheat, rye, rice, sorghum, millet, corn, hemp, flax, bagasse, cotton, bamboo, sisal, sabai, jute, ramie and reed.
Preferably the agricultural plant is a cereal plant. The cereal plant may be any of those known to the skilled person and may be, for example, one or more selected from the group consisting of barley, wheat, rye, rice, sorghum, millet, and corn. Preferably, the cereal plant may be one or more selected from the group consisting of barley, wheat, and rice, more preferably barley or wheat, especially barley. Preferably, the cereal plant fibres comprise cereal plant stalk fibres, which may also be known as straw fibres.
The wood fibres may be one or more selected from the group consisting of softwood fibres, and hardwood fibres.
The wood fibres present in the composition may be virgin fibres, recycled fibres or a mixture thereof. Preferably the wood fibres present in the composition are predominantly recycled fibres. Still more preferably the wood fibres present in the composition are recycled fibres. The composition of the present invention can accommodate the presence of significant amounts of recycled fibres, without compromising the mechanical performance of its end products, due to the presence of the agricultural plant fibres, in particular cereal plant fibres, and especially barely or wheat fibres.
Preferred recycled wood fibres comprise (e.g. consist of) old corrugated container (OCC) fibres. The length of the 000 fibres may be between 0.1 mm and 3 mm, preferably from 1 mm to 2 mm, for example 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2 mm.
The compositions of the present invention may comprise agricultural plant fibres in any amount. Preferably, compositions of the present invention may comprise agricultural plant fibres in an amount of up to 95% by weight based on the total weight of the composition, preferably up to 75%, preferably up to 50%, preferably from 5% to 45% by weight based on the total weight of the composition, more preferably 10% to 30% by weight based on the total weight of the composition, for example, 10, 12, 14, 16, 18, 20, 22, 24, 25, 26, 28 or 30% by weight based on the total weight of the composition.
A ratio of the first component to the second component may be from 1:15 to 2:1 by weight, preferably from 1:10 to 1.5:1 by weight, for example, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2 or 1.5:1 by weight. In preferred compositions, wherein the first component comprises barley or wheat fibres and the second component comprises virgin softwood or hardwood fibres, the ratio of the first component to the second component may be from 1:2 to 1:1 by weight. In other preferred compositions, wherein the first component comprises barley or wheat fibres and the second component comprises recycled wood fibres such as OCC, the ratio of the first component to the second component may be from 1:9 to 1:4 by weight. The present inventors have discovered that including barley or wheat straw in these amounts significantly improves the strength of the paperboard or paper, in particular when recycled fibres are used. In these compositions, the barley or wheat fibres preferably have an average fibre length of from 0.8 to 1.1 mm, an average fibre width of from 8 to 18 μm, and the composition has a lignin content of 8% to 14% by weight.
The average length of the agricultural plant fibres is preferably at least 0.5 mm, preferably from 0.5 to 5 mm, more preferably from 0.6 to 2 mm, more preferably 0.8 to 1.1 mm, for example, 0.8, 0.9, 1.0, or 1.1 mm. The average length of the agricultural plant fibres may also be from 0.5 mm to 1 mm, for example 0.5, 0.6, 0.7, 0.8, 0.9, or 1 mm.
The average width or average diameter of the agricultural plant fibres is preferably from 5 to 30 μm, preferably from 8 to 18 μm, for example, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 μm.
The ratio of the average length to the average width of the agricultural plant fibres is preferably from 50:1 to 500:1, preferably from 60:1 to 200:1, more preferably from 75:1 to 150:1, more preferably from 100:1 to 120:1, for example, 100:1, 105:1, 110:1, 115:1, or 120:1.
The coarseness of the agricultural plant fibres is preferably less than 1 mg/m, preferably less than 0.9 mg/m, more preferably less than 0.1 mg/m.
The α-cellulose of the agricultural plant fibres is not particularly limited and the agricultural plant fibres may comprise α-cellulose in an amount of from 15 to 40% by weight, preferably from 19 to 35% by weight, more preferably 31 to 34% by weight, for example 31, 32, 33, 34% by weight.
The amount of lignin in the agricultural plant fibres is not particularly limited and the agricultural plant fibres may comprise lignin in an amount less than 20% by weight, preferably from 1 to 15% by weight, more preferably 5 to 15% by weight, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 0115% by weight.
In particularly preferred compositions of the present invention, the first component may comprise barley fibres or wheat fibres; and, the second component may comprise virgin wood fibres or recycled wood fibres. In compositions in which the first component comprises barley or wheat fibres; and, the second component comprises virgin wood fibres, the barley or wheat fibres may be present in an amount of up to 50% by weight based on the total weight of the composition, preferably from 25 to 50%. In compositions in which the first component comprises barley or wheat fibres; and, the second component comprises recycled fibres such as OCC, the barley or wheat fibres may be present in an amount of up to 50% by weight based on the total weight of the composition, preferably from 10 to 30%. The present inventors have discovered that including barley or wheat straw in these amounts significantly improves the strength of the paperboard or paper, in particular when recycled fibres are used. In these compositions, the barley or wheat fibres preferably have an average fibre length of from 0.8 to 1.1 mm, an average fibre width of from 8 to 18 μm, and the composition has a lignin content of 8% to 14% by weight.
The compositions of the present invention may further comprise water, e.g. to bring the total weight of the composition to 100 wt %. The water content of the composition may depend on the papermaking process in which it is used. For example, the water content of the composition may up to 96% by weight, preferably from 75% to 96%, particularly at the wet end of the papermaking machine. The water content of a dried composition may be up to 25% by weight, more preferably from 4% to 20%, more preferably from 7% to 15%.
The compositions of the present invention may further comprise additives that those skilled in the art of papermaking may include in compositions for making paperboard and paper. Examples of suitable additives include sizing agents such as alkyl ketene dimers (AKD), alum, albietic acid, and/or alkenyl succinic anhydride (ASA); silicas; pigments and dyes such as titanium dioxide zinc oxide and/or casein; non-ionic, cationic or anionic retention aids; adhesives; acidity regulators such as calcium carbonate; bleaches; fillers such as barium sulfate; binders; and, bonding agents such as carboxymethyl cellulose. Preferably the total amount of additives present in the composition is 0.1 to 20 wt %, more preferably 0.2 to 10 wt %, and more preferably 0.5 to 5 wt %.
In a further aspect, the present invention is directed to a method of making a composition as described above, comprising the steps of: mixing a first component comprising agricultural plant fibres, and a second component comprising wood fibres. Mixing may be achieved by any conventional method known in the art.
In a further aspect, the present invention is directed to a paperboard or paper prepared from the compositions as described above.
In a further aspect, the present invention is directed to paperboard or paper comprising the compositions as described above.
The paperboard or paper of the present invention may be obtained from the compositions of the present invention using conventional methodology. The paperboard or paper of the present invention may be derived from the compositions of the present invention. Generally speaking, the paperboard or paper is obtained or derived from the compositions of the invention by conventional methodology, which comprises removal of water (and other solvents) present in the, e.g. pulp composition.
The grammage of the paperboard or paper of the present invention is preferably at least 90 g/m2, preferably from 100 to 800 g/m2, preferably from 250 to 450 g/m2, preferably from 310 to 390 g/m2, for example, 310, 320, 330, 340, 350, 360, 370, 380, or 390.
The thickness of the paperboard or paper of the present invention is preferably from 200 to 1200 μm, preferably from 300 to 1000 μm, preferably 400 μm to 700 μm, preferably from 450 μm to 550 μm, more preferably from 450 μm to 500 μm, for example, 450, 460, 470, 480, 490, or 500 μm.
The paperboard or paper of the present invention may have at least one, preferably two, and still more preferably all, of the following properties:
The paperboard or paper of the present invention may have at least one, preferably two, and still more preferably all, of the following properties:
The water absorbency of the paperboard or paper may be up to 50 g/m2 measured according to the COBB 60 method, optionally 0.5 to 40 g/m2, optionally 20 to 35 g/m2.
In a further aspect, the present invention is directed to a method of preparing paperboard, paper or packaging comprising:
Optionally the paperboard or paper is folded to make packaging.
In a further aspect, the present invention is directed to use of a composition as described above in the manufacture of paperboard, paper or packaging.
In a further aspect, the present invention is directed to packaging comprising the composition as described above.
In a further aspect, the present invention is directed to packaging prepared from the composition according to any one of the preceding claims.
The packaging of the present invention can be any type of packaging but is preferably primary, secondary, or tertiary packaging. Preferably the packaging is secondary or tertiary packaging suitable for beverage containers, such as regular slotted containers, crates, folding cartons for (including but not limited to) baskets, wraparound packages, neck-through wraparound packages, cluster wraparound packages, open and closed baskets, trays, fully enclosed packs, fridge packs, suitcases, top clusters, rings, clips, top clips, moulded fibre, sleeves, fibre hi-cones, or box partitions.
The present invention will now be further exemplified with reference to the following examples. The present invention is in no way limited to the given examples.
Methods of Measurement
The following methods were used to measure the parameters described in Table 1. Fibre coarseness measured according to ISO 9184-6:1994.
Paperboard Grammage—measured according to ISO 536/TAPPI 410.
Paperboard Thickness—measured according to ISO 186/TAPPI 400.
Paperboard Water absorption (Cobb60)—measured according to ISO 535/TAPPI 441.
Paperboard Tensile strength Machine Direction (MD) and Cross Direction (CD) Dry—measured according to ISO 1924/TAPPI 494.
Paperboard Tensile strength Machine Direction (MD) and Cross Direction (CD) Wet—measured according to ISO 1924/TAPPI 494 with 1 minute immersion.
Paperboard Tear strength Machine Direction (MD) and Cross Direction (CD) Dry measured according to ISO 1974/TAPPI 414.
Paperboard Tear strength Machine Direction (MD) and Cross Direction (CD) Wet—measured according to ISO 1974/TAPPI 414 with 3 minutes immersion.
Pulp Preparation
The compositions of the Examples were prepared by combining barley straw fibres or wheat straw fibres with either recycled wood fibres (OCC) or softwood fibres in the amounts recited in row 2 of Table 1 below. These compositions were processed into a pulp by combining the raw materials in a digester under alkaline conditions with heat applied depending on the raw materials used. Lignin was removed in the process to separate the fibres with minimal mechanical action. The pulp was then washed to remove residual chemicals.
Paperboard Preparation
The paperboard of the Examples was made by refining the pulp and mixing it with water and other additives (including alkyl ketene dimer (AKD) or alkenyl succinic anhydride (ASA)) to make a pulp slurry. The head-box of the paperboard machine (Fourdrinier mill or cylinder mill) distributed the slurry onto a moving continuous screen, drained water from the slurry, passed the wet paperboard sheet through presses and driers, and rolled the paperboard into rolls. Coatings such as wax were applied if needed.
Table 1 presents data on the physical parameters of paperboard made using the compositions of the present invention (see Example 1 to 7). These data demonstrate that the paperboard of the present invention performs at least as well as a commercial paperboard made entirely from virgin wood fibres (Reference Example 1), with the additional advantage that it is at least partially, if not entirely, made from recycled or waste material. The paperboard of the present invention is ideal for use in secondary packaging such as packaging for beer bottles or cans, which requires the package to carry relatively high weight and where liquid from condensation or spillages can affect the integrity of the packaging.
