Patent Application
20190226141
The present invention relates to bio-based polyelectrolyte complex (PEC) compositions which are environmentally benign, renewable and biodegradable. The PEC compositions comprise chitosan as a cationic polymer, an anionic polymer being represented by polyanions derived from nature, especially polysaccharides, and one or more additives.
The PEC compositions according to the present invention are suitable as binders for fiber based materials, textiles, woven and nonwoven materials. The treatment of fiber based materials, textiles, woven and nonwoven materials with the PEC composition of the present invention provides materials which have higher dry and/or wet strengths, i.e. higher dry and/or wet tensile indexes. Thanks to the one or more additives they contain, the PEC compositions can transfer specific properties of the additives to the treated materials.
PECs are the association complexes formed between oppositely charged particles such as polymer-polymer, polymer-drug and polymer-drug-polymer. These complexes are formed due to electrostatic interaction between oppositely charged polyions and thereby avoids the use of chemical cross linking agents (S. Lankalapalli, 2009). Based on origin PECs are classified as natural polyelectrolytes, synthetic polyelectrolytes and chemically modified biopolymers.
The PEC composition according to the present invention comprises organic molecules of biological origin (i.e. biopolymers) represented by polyanions derived from nature which are either natural polyelectrolytes or chemically modified biopolymers. Hence, the PECs do not comprise synthetic polymers and synthetic polyelectrolytes and therefore the PEC compositions according to the present invention are bio-based PEC compositions.
EP0723047 relates to PEC suspensions for papermaking. However, the PEC suspensions do not comprise chitosan as a cation. Instead the cation is a synthetic polymer such as a copolymer of acrylamide with diallyldimethylammonium chloride. Hence, the PECs in EP0723047 are not bio-based PECs. More importantly, there is no data or reference to (i) any increase in wet strength of treated materials, (ii) effect on tensile stiffness of treated materials, and/or (iii) stability of the PECs over a period of several months.
EP1918455 relates to producing fibrous webs by using PECs having a negative net charge. Furthermore, the PECs do not comprise chitosan as a cation. Instead the cation is a synthetic polymer such as acrylic polymers, polyacrylamides and amido-amine polymers. Consequently, the PECs according to EP1918455 are not bio-based.
U.S. Pat. Nos. 8,993,505, 9,012,389 and 9,273,220 relate to PECs for reduced soiling tendency, reduced cleaning effort and reducing microbial challenge. However, the PECs are not wholly of biological origin since they in addition to biopolymers also comprise synthetic polymer such as (i) homopolymer of diallyl dimethyl ammonium chloride “DADMAC” disclosed in claim 1 of U.S. Pat. No. 8,993,505, (ii) homopolymer of acrylic acid or a random copolymer of acrylic acid disclosed in claim 1 of U.S. Pat. No. 9,012,389, (iii) homo- or copolymers of the following anionic monomers: acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, styrene sulfonic acid and acrylamide propane sulfonic acid disclosed in U.S. Pat. No. 9,273,220.
Consequently, the PECs according to U.S. Pat. Nos. 8,993,505, 9,012,389 and 9,273,220 are not bio-based. More importantly, there are no data or reference to (i) any increase in dry strength and wet strength of treated materials, (ii) effect on tensile stiffness of treated materials, and/or (iii) stability of the PECs over a period of several months. Hence, none of U.S. Pat. Nos. 8,993,505, 9,012,389 and 9,273,220 have the same purpose or aim as the present invention.
US2013216592 relates to PECs consisting of biopolymers. More importantly, there are no data or reference to (i) any increase in dry strength and wet strength of treated materials, (ii) effect on tensile stiffness of treated materials, and/or (iii) stability of the PECs over a period of several months. Hence, US2013216592 does not have the same purpose or aim as the present invention.
U.S. Pat. No. 6,936,746 relates to PEC solid material systems. Hence, the PECs are in the form of solid materials and not as solutions. Moreover, U.S. Pat. No. 6,936,746 is silent about the net charge of the PECs. Furthermore, U.S. Pat. No. 6,936,746 is also silent about the charge ratio between the cationic polymer and the anionic polymer. More importantly, there is no data or reference to (i) any increase in dry strength and wet strength of treated materials, (ii) effect on tensile stiffness of treated materials, and/or (iii) stability of the PECs over a period of several months. U.S. Pat. No. 6,936,746 does not have the same purpose or aim as the present invention.
Furthermore, specific embodiments of PEC composition described in the prior art have a concentration of 0.04% PEC due to stability issues. Hence there is also a need for PEC compositions having a higher concentration of PEC.
It is an object of the present invention to overcome the drawbacks and disadvantages of the above described compositions and to provide a bio-based PEC composition that is environmentally benign, renewable and biodegradable.
A further object of the present invention is to transfer mechanical properties (dry strength, wet strengths, tensile stiffness and/or tensile softness) to materials treated with a PEC composition.
A further object of the present invention is to transfer hydrophobicity to materials treated with a PEC composition.
A further object of the present invention is to transfer hydrophilicity to materials treated with a PEC composition.
A further object of the invention is to provide a bio-based PEC composition which is stable for at least 1.5 months.
A further object of the invention is to provide a bio-based PEC composition comprising at least 0.04 wt %, preferably at least 1.5 wt % PEC, more preferably at least 4 wt % PEC, most preferably 4-10 wt % PEC.
A further object of the invention is to provide a bio-based PEC composition which does not mold.
A further object of the invention is to provide a bio-based PEC composition which comprises an anionic biopolymer which has a low cost.
A further object of the invention is to provide a bio-based PEC composition which is suitable as a binder for fiber based materials, textile, woven and nonwoven materials, and for pulp, paper and paperboard.
A further object of the invention is to provide a bio-based PEC composition which is stable in tap water. According to prior art minerals in water destabilizes the PEC.
A further object of the invention is to provide a bio-based PEC composition having the ability to transport and transfer specific properties from additives, such as wet tensile strength, hydrophobicity, etc. to fiber based materials, textiles, woven and nonwoven materials.
A further object according to the invention is to provide a biopolymer PEC composition, wherein the nonwoven materials are mineral fibres such as glass or rock fibres.
A further object of the invention is to provide a method for achieving the above bio-based PEC compositions.
A further object of the invention is to provide fiber based, textile, woven and nonwoven materials which have (i) high wet tensile strength, and/or (ii) high dry tensile strength and/or (iii) softness and/or (iv) stiffness and/or (v) hydrophobicity.
Any combination of the above objects is also possible.
The objects of the invention are attained by a bio-based PEC composition comprising cationic biopolymer, anionic biopolymer, acid and preservative. The expression bio-based indicates that the PEC composition is of biological origin.
The PEC composition of the present invention further comprises non-water soluble particles. By non-water soluble particles are herein understood any solid compound having a solubility in water not exceeding 15 wt %. Further non-water soluble particles are one or more plastic particles and/or bioplastic particles and/or protein particles and/or hydrophobic particles.
While the PEC composition is of biological origin, the non-water soluble particles and the additives can be, independently of each other, of natural or synthetic origin.
The net charge of the PEC composition is cationic and the charge ratio between the anionic polymer and the cationic polymer is 1. Moreover, the weight ratio between cationic polymer and anionic polymer is 1:0.1 to 1:20. Ratios in the present invention are weight ratios unless otherwise indicated.
The PEC composition according to the present invention comprises chitosan which imparts higher tensile index when compared to other cations such as cationic starch and cationic cellulose. Hence, the preferred embodiments of the invention comprise cationic chitosan as cationic biopolymer. The concentration of chitosan in the composition is 0.005-30 wt %, Moreover, chitosan preferably has a degree of deacetylation which ranges from 66%-100%. The degree of deacetylation is important for the physical properties of chitosan in the PEC composition.
The anionic biopolymer being a polyanion derived from nature can be selected from lignin alkali, lignosulfonic acid, or a polysaccharide, such as carboxymethyl cellulose (CMC), alginic acid (preferably the sodium salt), xanthan gum, pectin, carrageenan and nanocrystalline cellulose (NCC) and gum arabic. Lignin alkali and lignosulfonic acid may preferably be in the form of their sodium salt. The concentration of anionic biopolymer in the composition is 0.005-30% by weight. Concentrations in % in the present invention are concentrations in weight % unless otherwise indicated.
The pH of the PEC composition is below pH 7 and this may be achieved by Brønsted acid and/or a Lewis acid. Preferably, the pH of the PEC composition is lower than 6.5. Brønsted acids are selected from any organic or inorganic acids, wherein the concentration of the acid is 0.01-30%. Lewis acids are selected from any cationic mono- or multivalent atom, wherein the concentration of the Lewis acid is 0.01-30 The PEC composition preferably has a pH value of 24. The weight ratio between the cationic polymer and the acid is 1:0.01 to 1:30 in the PEC composition. The acid of the PEC composition is selected from one or more of acetic acid, acetylsalicylic acid, adipic acid, benzenesulfonic acid, camphorsulfonic acid, citric acid, dihydroxy fumaric acid, formic acid, glycolic acid, glyoxylic acid, hydrochloric acid, lactic acid, malic acid, malonic acid, maleic acid, mandelic acid, oxalic acid, para-toluenesulfonic acid, phthalic acid, pyruvic acid, salicylic acid, sulfuric acid, tartaric acid and succinic acid, more preferably citric acid, oxalic acid and tartaric acid, even more preferably citric acid, and most preferably citric acid monohydrate.
The concentration of the PEC in the PEC composition is at least 0.04 wt % PEC, preferably at least 1.5 wt % PEC, more preferably at least 4 wt % PEC, most preferably 4-10 wt % PEC. Furthermore, the PEC composition according to the present invention is dilutable. Manufacturing of highly concentrated PEC compositions is advantageous in view of lowering shipping cost, i.e. the PEC composition can be prepared with a high concentration and then diluted after shipping by the user or customer.
The solvent of the PEC composition is water selected from distilled water, tap water, and deionized water. PEC compositions comprising chitosan are in the prior art known for being unstable in tap water and are therefore prepared in distilled water. However, the PEC composition according to the present invention is stable in tap water.
The PEC composition of the present invention may also be prepared in neat form, i.e. the PEC composition does not comprise added water.
The PEC composition comprises one or more additives selected from, water soluble plasticizer, defoamer, foaming agent, wetting agent, coalescent agent, catalyst, surfactant, emulsifier, conservative, cross-linker, rheology modifier, filler, nonionic polymer, dye, pigment. Said one or more additives are selected depending on the application method and the expected properties of the final material, wherein the concentration of the additive(s) is 0-99 wt %, preferably 0-50 wt %, most preferably 0-30 wt %.
The preservative may be selected from the group consisting of a fungicide, bactericide, pharmaceutical preservative, cosmetic preservative and/or food preservative. The concentration of the preservative is 0.005-10 wt %, preferably 0.005-1.5 wt %, more preferably 0.005-0.5 wt %. Moreover, the preservative is preferably biodegradable and/or renewable. Food preservatives, pharmaceutical preservatives and cosmetic preservatives are preferred since they are non-toxic. The inclusion of a preservative helps to inhibit the growth of mold in the PEC composition. Moreover, we have discovered that PEC compositions without preservative becomes more yellow/brown than a composition comprising preservative. Even if performance is the same between the more yellow and less yellow PEC composition, the yellow color is transferred to material and causes yellowing which is unwanted especially for nonwovens and fiber based materials such as textiles.
The PEC composition of the present invention further comprises one or more non-water soluble particles. The composition's ability to incorporate and transport the non-water soluble particles gives the opportunity of transferring the properties of named non-water soluble particles to different materials treated with the PEC composition. This ability is explored by the present invention.
The non-water soluble particles of the present invention may be present in the PEC composition at a weight ratio of PEC:non-water soluble particles of 1:0.01 to 1:50, preferably 1:0.05 to 1:20, more preferably 1:0.1 to 1:10, most preferably 1:0.5 to 1:1. Moreover, the non-water soluble particles of the present invention have a particle size preferably in the range of 100 nm-1 mm, more preferably of 100 nm-500 μm, even more preferably of 100 nm-300 μm.
The non-water soluble particles may be of the following types, namely plastics, bioplastics, hydrophobic particles, proteins, solid waxes, solid resins, fillers, pigments, fumed silica, and mixtures thereof.
The plastics employed in the PEC composition of the present invention may be selected from the group consisting of Polyester, Polyethylene terephthalate, Polyethylene, High-density polyethylene, Polyvinyl chloride, Polyvinylidene chloride, Low-density polyethylene, Polypropylene, Polystyrene, High impact polystyrene, Polyamides, Acrylonitrile butadiene styrene, Polyethylene/Acrylonitrile Butadiene Styrene, Polycarbonate, Polycarbonate Butadiene Styrene, Acrylonitrile Butadiene Styrene, Polyurethanes, Maleimide, Bismaleimide, Melamine formaldehyde, Phenolics, Polyepoxide, Polyetheretherketone, Polyetherimide, Polyimide, Polymethyl methacrylate, Polytetrafluoroethylene, Urea-formaldehyde, Furan resin, Silicone, Polysulfone, Polyoxymethylene, preferably selected from Polycaprolactone, Polyethylene terephthalate, Polyethylene, Polypropylene and mixtures thereof.
Where the plastics are of biological nature, they can preferably be selected from the group consisting of polylactic acid (PLA), PLA co-coplymers such as L-PLA, D-PLA, DL-PLA, PLGA, PDLA, polyhydroxy alkanoates (PHA) and variations of thereof such as PHB, PHBV, P3HB, P4HB, PHbHHx, P(3HB-co 20% mol-3HV, P(3HB-co 4HB), P(3HB-co 6% mol-3HA), P(3HB-co 4HP), P(3HB-co 3HHX), PHBHHx), ethylcellulose, cellulose acetate, thermoplastic starch, polybutylene succinate, preferably selected from PLA, PHA and thermoplastic starch, and mixtures thereof.
PEC composition according to the present invention may contain proteins as non-water soluble particles, preferably selected from one or more of pea protein, vital wheat gluten, wheat gluten, lupine protein, soy protein, soybean protein, maize protein, zein protein, peanut protein, caseine, and similar plant-based or yeast based proteins as isolates and/or flours. Other useful proteins are hydrophobins (small proteins of from about 100 to 150 amino acids and are characteristic of filamentous fungi, for example Schizophyllum commune. They generally have 8 cysteine units.), keratin, animal protein such as fish protein, albumin, milk protein, and Non-limiting examples of other sources of vegetable protein include, for example, proteins extracted from nuts, seeds, grains, and legumes. These sources include, but are not limited to, almonds, brazil nuts, cashews, walnuts, pecans, hazel nuts, macadamia nuts, sunflower seeds, pumpkin seeds, corn, and the like. Other sources include protein-containing biomasses, such as waste sludge, manure, and composted manure. More preferred proteins are pea protein, vital wheat gluten, wheat gluten, lupine protein, soybean protein, maize protein, zein protein, caseine and keratin.
The non-water soluble particles may originate from solid waxes, as vegetable and/or animal waxes, having a melting point of 27° C.-220° C. They may preferably be selected from the group consisting of Bayberry wax, candelilla wax, carnauba wax, castor wax, esparto wax, japan wax, ouricury wax, rice bran wax, soy wax, tallow tree wax, beeswax, Chinese wax, lanolin wax (wool wax), shellac wax, spermaceti wax, and mixtures thereof.
The solid waxes may as well be mineral, synthetic waxes and/or petroleum derived waxes, and may have a melting point of 27° C.−220° C. They may preferably be selected from the group consisting of paraffin wax, microcrystalline wax, ceresin wax, montan wax, ozocerite wax, polyethylene wax, peat wax, and mixtures thereof.
The non-water soluble particles may be solid resins. The solid resin may be plant and/or animal and/or petroleum derived resins and/or synthetic resin preferably selected from the group consisting of petroleum resin such as asphaltite and Utah resin, insect resins such as shellac, plant resins such as copals, dammars, mastic, and sandarac, oleo-resins (frankincense, elemi, turpentine, copaiba), gum resins and Aleppo pine resin, synthetic resins such as bisphenol A diglycidyl ether and silicone resins. More preferred solid resins are selected from plant based resins such as furan, rosin and gum resins.
Thenon-water soluble particles of the present invention may be inorganic and/or organic pigments.
The fillers and pigments used as non-water soluble particles may preferably be selected from the group consisting of clay, calcium carbonate, titanium dioxide, talc, iron oxides, barium sulfate, barium carbonate, aluminium sulfate, kaolinite, calcium magnesium carbonate, magnesium carbonate, satin pigment, zinc oxide and zinc sulfide, more preferably selected from clay, titanium dioxide, and aluminum sulfate and mixtures thereof.
The composition can additionally comprise an acid or basic catalyst which has in particular the role of adjusting the temperature at which crosslinking begins. The catalyst can be chosen from Lewis bases and acids, such as clays, colloidal or noncolloidal silica, organic amines, quaternary amines, metal oxides, metal sulphates, metal chlorides, urea sulphates, urea chlorides and catalysts based on silicates.
The catalyst can also be a phosphorus-comprising compound, for example an alkali metal hypophosphite salt, an alkali metal phosphite, an alkali metal polyphosphate, an alkali metal hydrogenphosphate, a phosphoric acid or an alkylphosphonic acid. Preferably, the alkali metal is sodium or potassium.
The catalyst can also be a compound comprising fluorine and boron, for example tetrafluoroboric acid or a salt of this acid, in particular an alkali metal tetrafluoroborate, such as sodium tetrafluoroborate or potassium tetrafluoroborate, an alkaline earth metal tetrafluoroborate, such as calcium tetrafluoroborate or magnesium tetrafluoroborate, a zinc tetrafluoroborate and an ammonium tetrafluoroborate. Preferably, the catalyst is sodium hypophosphite, sodium phosphite and the mixtures of these compounds.
The amount of catalyst introduced into the composition can represent up to 20 wt %, preferably up to 10%, and advantageously is at least equal to 1%.
In an embodiment of the invention, the PEC composition comprises chitosan, CMC and citric acid. In a preferred embodiment of the invention, the PEC composition may comprise 0.75-6 wt % chitosan, 0.75-6 wt % CMC and 6-30 wt % citric acid monohydrate. In a further preferred embodiment of the invention, the PEC composition comprises 0.75-6 wt % chitosan, 0.75-6 wt % CMC and 6-24 wt % citric acid monohydrate. In a further preferred embodiment of the invention the PEC composition comprises 0.75-4 wt % chitosan, 0.75-4 wt % CMC and 6-24 wt % citric acid monohydrate.
In a further preferred embodiment of the invention, the PEC composition comprises 0.75-2 wt % chitosan, 0.75-2 wt % CMC, 9-12 wt % citric acid monohydrate, and 0.75-4 wt % non-water soluble particles. The non-water soluble particles may comprise bioplastic or protein particles. In an embodiment of the invention, the PEC composition comprises 0.75 wt % chitosan, 0.75 wt % CMC, 9 wt % citric acid monohydrate, and 0.75-1.5 wt % non-water soluble particles. In another embodiment of the invention, the PEC composition comprises 2 wt % chitosan, 2 wt % CMC, 12 wt % citric acid monohydrate, and 2-4 wt % non-water soluble particles.
In an embodiment of the above disclosed PEC compositions comprising chitosan, CMC, citric acid and non-water soluble particles, the non-water soluble particles may comprise bioplastic particles, preferably polylactic acid (PLA) particles. The PEC:bioplastic particles weight ratio may be 1:0.5 to 1:2, more preferably the weight ratio may be 1:1 to 1:2. The bioplastic particles preferably comprise PLA-particles. In preferred embodiments of the invention, the PEC composition may further comprise plasticizer, surfactant and/or stabilizer.
In an embodiment of the above disclosed PEC compositions comprising chitosan, CMC, citric acid and non-water soluble particles, the non-water soluble particles may comprise protein particles, preferably soy protein concentrate (SPC), lupine protein concentrate (LPC), pea protein (PP), wheat gluten (WG) and/or vital wheat gluten (VWG). The PEC composition may comprise PEC:protein particles with weight ratio 1:0.5 to 1:2.40. The PEC composition may further comprise defoamer.
The objects of the invention are also attained by a method of preparing the above disclosed embodiments of PEC compositions. The method comprises the steps of mixing chitosan, anionic polymer, acid, preservative, water and non-water soluble particles and optionally one or more additives. The method may comprise one or more homogenization steps.
In a preferred embodiment, the method comprises the steps of:
The objects of the invention are also attained by using the above disclosed embodiments of PEC compositions as a binder for fiber based, textile, woven and nonwoven materials. The use of the PEC composition is preferably for providing mechanical properties to said fiber based materials, textiles, woven and nonwoven materials, and wherein said mechanical properties are selected from dry strength, wet strengths, tensile stiffness and tensile softness
The objects of the invention are also attained by fiber based, textile, woven and nonwoven materials comprising the above disclosed embodiments of PEC compositions as a binder.
The objects of the invention are also attained by an apparatus comprising the above disclosed embodiments of PEC compositions as a binder. The apparatus is any kind of laboratory or industrial equipment using low or high shear forces for producing; the PEC compositions. This might be a magnet stirrer, overhead stirrer with propeller or disperser or like, homogenizer with or without high pressure, in-line or external homogenizers, extruders, shaking equipment, mortar and pestle, blender type of instrument, any kind of mixer (static mixer, micro mixer, vortex mixer, industrial mixer, ribbon blender, V blender, continuous processor, cone screw blender, screw blender, double cone blender, double planetary, high viscosity mixer, counter-rotation, double and triple shaft, vacuum mixer, high shear rotor stator, dispersion mixer, paddle, jet mixer, mobile mixer, drum mixer, intermix mixer, planetary mixer, Banbury mixer or like), French press, disintegrator, mill (grinding by bead mill, colloid mill, hammer mill, ball mill, rod mill, autogenous mill, semi-autogenous grinding, pebble mill, high pressure grinding rolls, buhrstone mill, vertical shaft impactor mill, tower mill or ultrasonic treatment, rotor-stator mechanical equipment, any kind or propeller or mixer, high temperature and/or high pressure bitumen emulsifiers or combinations of the above.
The objects of the invention are also attained by a method of treating fiber based, textile, woven and nonwoven materials with the above disclosed embodiments of PEC compositions as a binder, comprising the steps of:
In a preferred embodiment, the method of treating comprises the step of curing the treated fiber based and nonwoven materials. In a further preferred embodiment, the curing is performed at 20° C. to 200° C., preferably at 80° C. to 190° C., more preferably at 120° C. to 180° C.
The present invention relates to bio-based PEC compositions that are environmentally benign, renewable and biodegradable mixtures of a cationic biopolymer and an anionic biopolymer. The cationic and anionic polymers are balanced so that the net charge of the PEC is cationic. The PEC compositions are preferably prepared in the presence of an acid and further comprise non-water soluble particles. The PEC compositions are suitable as binders for fiber based materials, textiles, woven and nonwoven materials.
Non-water soluble particles refer herein to solid compounds having a solubility in water not exceeding 15 wt %. The non-water soluble particles of the present invention have a particle size preferably in the range of 100 nm-1 mm, more preferably of 100 nm-500 μm, even more preferably of 100 nm-300 μm.
According to the invention the use of the wording textiles, woven and nonwoven may include cloths or fabrics and may be based on natural or synthetic fibers and mixtures thereof.
Textiles, woven and nonwoven may consist of a network of natural and/or synthetic fibers often referred to as thread or yarn. Yarn is produced by spinning raw fibers of wool, flax, cotton, or other material to produce long strands. Textiles are formed by weaving, knitting, crocheting, knotting, or pressing fibers together (felt). The words fabric and cloth may for example be used in textile assembly trades (such as tailoring and dressmaking) as synonyms for textile. Textile may refer to any material made of interlacing fibers or nonwoven textiles. Fabric refers to any material made through weaving, knitting, spreading, crocheting, or bonding that may be used in the production of further goods (garments, etc.). Cloth may be used synonymously with fabric but often refers to a finished piece of fabric used for a specific purpose (e.g., table cloth). The wording textiles, woven and nonwoven according to the present invention may include all different types of textiles described above. Textiles, woven and nonwoven according to the invention can be made from many different types of materials and fibers for example animal, plant, wood, mineral, synthetic, sugar based, protein based for example wool, silk, mohair, cashmere, pygora, cameldown, alpaca, ilama, vicuna, guanaco, angora, qiviut, ramie, nettle, milkweed, cotton, linen, flax, jute, hemp, viscose, asbestos, glass fiber, rock fiber, nylon, elastan, polyester, acrylic, polyamide, polypropylene, polyurethane and its derivatives, cornfiber, coir, yucca, sisal, bamboo (rayon) fiber, peanut, soybased, chitin based, milk casein based, keratin based and poly lactic acid based etc. Further, nonwoven materials are fabric-like materials made from long fibers, bonded together by chemical, mechanical, heat or solvent treatment. Nonwoven fabrics are also defined as sheet or web structures bonded together by entangling fiber or filaments (and by perforating films) mechanically, thermally or chemically. The term is used in the textile manufacturing industry to denote fabrics, such as felt, which are neither woven nor knitted. They are flat or tufted porous sheets that are made directly from separate fibers, molten plastic or plastic film.
Fiber based materials refer to materials such as paper materials which comprise a high degree of cellulose. As will be understood by those skilled in the present field of art, numerous changes and modifications may be made to the above described and other embodiments of the present invention, without departing from its scope as defined in the appending claims. For example, the pulps for making fiber based materials may be any kind of pulp, i.e. mechanical pulp, thermo-mechanical pulp, chemo-mechanical pulp, sulphate pulp, sulphite pulp, bleached pulp, unbleached pulp, short-fiber pulp, long-fiber pulp, recycled fibers, mixtures of different pulp grades etc. The invention works irrespective of the kind of pulp chosen.
The Examples relate to comparative studies and for investigating the ability of PEC to create dispersions of non-water soluble particles such as bioplastics and proteins as well as the ability of PEC to transfer the properties of the dispersed particles to different materials through electrostatic attraction. To the person skilled in the art it will be obvious that the present invention can also be transferred to other types of particles such as pigments, fillers and similar non-water soluble particles.
The PEC composition according to the present invention can be used as a vehicle in the sense that said composition both has space for and fuel to transport other molecules. In more specific terms, the PEC composition can form a micelle around, for example non-water soluble particles comprised in the PEC composition and thanks to its positive charge, it can thereafter arrange itself towards negatively charged fibers and thus transfer the properties of the non-water soluble particles to the fiber based material.
Charge Ratio
Charge density was measured using the Mütek PCD 02 device. Charge (symbol: q, unit: meqv) was calculated using Eq. 1.
q [meqv]=Ccounter ion [eqv/l]·Vcounter ion [l]·1000 (1)
where the counter ion is one of sodium polyethylenesulphate (PES-Na, anionic) or poly-diallyl-dimethyl-ammonium-chloride (poly-dadmac, cationic), depending on the charge of the colloid. If the charge at different concentrations are plotted against mass of the current colloid, the charge density (unit: meqv/g) is the slope of the linear curve. The mass of the colloid can be calculated with Eq. 2.
m[g colloid]=wt % colloid [g colloid/g solution]·g [g solution for 10 ml]·0,0 (2)
The method above is for measuring charge density and then calculate the charge ratio.
The binder recipe OC-C (see details in abbreviations experiments 1-8) is based on polyelectrolyte complex (PEC). PEC gives good dry and wet mechanical properties to fiber based materials, nonwovens, paper and textiles. PEC can also be seen as a micelle that can emulsify for example non-water soluble particles. To mix PEC and non-water soluble particles can therefore lead to a dispersion that both gives good mechanical properties to materials (the PEC part of the dispersion) and that creates an additional property on the material which is derived from the particle the PEC composition carries (the particle part of the dispersion).
The experiments below demonstrate that PEC can support and stabilize non-water soluble particles in water to form dispersions. These are then further used as binders/additives on different materials and the properties measured. In the following examples the term particle PEC composition refers to polyelectrolyte complex dispersion containing non-water soluble particles while a polyelectrolyte complex formulation without particles is referred to non-particle PEC composition.
Below, all abbreviations used in experiments 1-8 are listed.
Below, all methods used in experiments 1-8 are listed.
Below, all equipment used in experiments 1-8 is listed.
Below, all chemicals used in experiments 1-8 are listed.
To produce bioplastic particles of suitable size, solvent exchange method was used. The polymer and/or plasticizers were dissolved in an organic solvent. The surfactant and stabilizer were dissolved in water. The organic phase was slowly added to the aqueous phase during mixing using UltraTurrax. The organic solvent was then evaporated. See Table 1 for the composition of the PLA- and EC-dispersions used.
1)According to Method 8.
To disperse bioplastic particles using PEC, OC-C was produced with a bioplastic dispersion (Dispersion 5, 6 or 7) as the “Water 1” in the recipe according to Method 7.
The particle PEC compositions PEC/Dispersion 5 (called particle PEC composition 5), PEC/Dispersion 6 (called particle PEC composition 6) and PEC/Dispersion 7 (called particle PEC composition 7) show good film forming properties when making 400 μm films with film applicator (drying overnight in 23° C.). Also, the dispersions have an even and homogenous texture showing that it is possible to use PEC as an emulsifier of bioplastic particles. The dispersions also look homogenous and non-flocculating when studied in microscope.
100% viscose NW was treated according to Method 1 with the particle PEC compositions from experiment 1. Hydrophobicity of the particle PEC compositions was studied according to Method 2, see Table 2.
Table 2 shows that the bioplastic dispersions themselves give hydrophilic NW (probably because of the surfactants) but together with the particle PEC composition of the invention the treated NW becomes hydrophobic. Particle PEC composition comprising PLA without softener gives the most hydrophobic NW.
Coating of 100% viscose NW with particle PEC compositions comprising bioplastic particles was done according to Method 1. Tensile tests were conducted according to Method 3. See results in Table 3. Dry tests were performed on 100% viscose NW.
Dry tensile stiffness increases significantly when PLA particles are used in PEC composition compared to PEC composition without. The required curing temperature, when using pure PLA particles in the PEC composition, is higher (180° C.) than when using PLA plasticized particles (150° C.) in the PEC composition, to reach similar dry tensile stiffness. This is due to the lowering of the melting point of the PLA particles imparted by the plasticizer. This gives the end user of the particle PEC composition an option to choose PLA particle PEC composition with and without a PLA plasticizer depending on the curing temperature used in the process. EC particles have no or small effect on the tensile stiffness index of the treated material.
In experiment 3 PLA particles used in the particle PEC composition had smaller particle size (see table 1) compared to the size of PLA particles used in particle PEC compositions in experiment 4.
Grinded PLA-powder with mixed particle size was filtered through 150 mesh wire, equal to <100 μm holes, and tested together with PEC in a particle PEC composition. The PEC-particles used had a melting point of 170° C. The filtered particles were dispersed in OC-C according to Method 7 to reach the ratio PEC:PLA-powder 1:1 and 1:2.
Treatment of NW was done according to Method 1 (curing in 140° C. and 170° C.). Dry properties were tested to investigate the dependence of ratio PEC:PLA, curing temperature and time. Tensile tests were done according to Method 3. The results are presented in Table 4
The difference in stiffness is dependent on both temperature and time. Curing at 140° C., did not melt all the PLA particles which could be observed on the material (dusty material). The stiffness did not increase when the ratio was changed from 1:1 to 1:2 PEC:PLA.
Based on the above conclusions NW was treated according to Method 1 (curing at 190° C. for 2, 4 and 6 min) to investigate the effect of curing time. Tensile tests were conducted according to Method 3. See results in Table 5. Dry tests were performed on 100% viscose NW.
The percentage increase in the different mechanical properties were calculated from Table 5 and are presented in Table 6. The comparison is performed between non-particle PEC composition and particle PEC composition for each curing temperature and time.
It is obvious that PLA-powder (melting point 170° C.) needs to melt properly to have an effect on the mechanical properties. Curing at 190° C. for 2 min results in 49% increase in strain/elongation for PEC compositions with addition of PLA-particles. Curing at 190° C. for 6 min results in 20% increase in dry tensile index for PEC compositions with addition of PLA-particles.
To evaluate the stability of the particle PEC composition comprising PEC:PLA-particle (150 mesh) 1:1, a test to treat NW with 6 weeks old formulation was performed. The NW was treated according to Method 1 (curing at 190° C. for 2 min). Tensile tests were conducted according to Method 3 and Method 4. Results are shown in Table 7. Dry tests were performed on 100% viscose NW and wet tests on 100% bio-based NW.
There is no significant change between the two series which shows that the particle PEC composition is stable.
The same stability study was performed for particle PEC composition 5 and particle PEC composition 6. The NW was treated according to Method 1 (curing at 180° C. for 3 min). Tensile tests were conducted according to Method 3 and Method 4. The results are shown in Table 8. Dry tests were performed on 100% viscose NW and wet tests on 100% bio-based NW.
As can be seen in Table 8, both the dry tensile stiffness and the wet tensile index are more or less unchanged for 7 weeks old particle PEC composition. One property that changes over time is dry tensile index which seems to slightly increase as the formulation is aged yielding a stronger material.
Since PEC disperses bioplastic particles well, it was tested to disperse other types of hydrophobic particles such as proteins (soy protein concentrate (SPC), lupine protein concentrate (LPC), pea protein (PP), wheat gluten (WG), vital wheat gluten (VWG)). Particle PEC composition with the ratio PEC:protein powder 1:0.5 was produced according to Method 7. A defoamer was added in 0.2 wt % concentration to reduce foam, resulting in smooth formulations which did not separate during storing for at least 1.5 months.
NW was treated with particle PEC composition comprising proteins with the ratio 1:0.5 (produced according to Method 7) according to Method 1. Tensile tests were conducted according to Method 3 and Method 4. See Table 9 for results. Dry tests were performed on 100% viscose NW and wet tests on 100% bio-based NW.
Same treated materials were tested for hydrophobicity according to method 2 presented in table 10.
Besides the fact that the tested proteins result in good dispersions, it is seen that by adding VWG to PEC, the wet strength can be increased. Almost all of the tested protein powders did not affect the dry tensile index negatively, showing that the powders did not interfere with the binding properties of PEC. Hydrophobic properties could be achieved by incorporating VWG and LPC. On the other hand, the inherent hydrophilicity of the PEC composition could be maintained when incorporating PP and at the same time boosting up wet strength.
PEC creates stable dispersions of bioplastic particles. The PEC compositions comprising bioplastic particles show good dry mechanical properties on NW. The dry mechanical properties are increasing with temperature and time. While the melting point of bioplastic particles is individual for each type of plastic, the treatment temperature and time need to be optimized for each case. The treated NW are showing low to excellent hydrophobicity.
PEC also creates good dispersions of many non-water soluble protein powders. NW treated with PEC composition comprising protein powders increase:
PLA is known to degrade in water and especially in acidic conditions which is a requirement for forming the PEC. This is however not observed in PLA PEC compositions of the present invention shown by the fact that mechanical properties change very little over time when comparing treated materials using freshly prepared particle PEC composition vs. aged composition.
To evaluate the ability of the particle PEC composition to transfer particle properties to fibers in a fiber suspension, paper sheets were produced where PEC composition without particles and particle PEC compositions were added in the wet end of the paper process respectively and compared. The formed paper sheets were evaluated with tensile tests, contact angle measurements and Gurley.
Below, all abbreviations used in experiments 13-14 are listed.
Below, the equipment used in examples 9-11 is listed.
Below, all chemicals used in experiments 9-11 are listed.
Paper suspension was made according to Method 10 and paper sheets with and without additives were produced according to Method 11. Since the amount of PEC in relation to fibers is important, it was decided to add the two formulations (OC-C and PEC+PLA) to the paper suspension so that amount of solid content in the formulations in relation to fibers became 1% respectively.
The formulations were diluted to 1 wt % based on total solid content (i.e. 10 g formulation and 130 g and 150 g water for OC-C and PEC+PLA, respectively), to receive a lower viscosity. Dry tensile tests were conducted using Method 15. The results are shown in Table 11.
Since PLA melts above 95° C. (which is the drying temperature in Rapid Köthen) it was tested to dry half the numbers of the paper sheet for the OC-C and PEC+PLA series at 190° C. for 3 min, see Table 12.
The inclusion of PLA to the PEC composition clearly shows that the PLA properties are transferred to the fibers in a pulp suspension. This yields a 21% increase in tensile index and a 11.7% increase in tensile stiffness index if the paper sheets are dried at 95° C. (see table 11). The differences in paper sheet properties are also obvious when comparing PLA PEC compositions (PEC+PLA) with only PEC composition (OC-C).
When paper sheets are subjected to an additional drying step (190° C./3 min) tensile index increase is further elevated to about 39% and increase on final strain to about 40% (see table 12). This further demonstrates the effect PLA PEC composition has on the paper sheets.
Contact angles for sheets produced according to Method 10 and Method 11 were measured. Table 13 shows the dynamic contact angle over a period of 60 s for paper with OC-C and PEC+PLA as additive when the 0.5% and 1% (d/d) additions to fiber was calculated on the total solid content.
In table 13 it can be seen that when using OC-C or PEC composition of the invention (PEC+PLA) as additive to pulp suspension a relatively elevated initial contact angle can be achieved which diminishes quickly. However, increasing drying time and temperature to 190° C. for 3 minutes yields a contact angle of 71.3° over 60 second for the PEC+PLA composition.
To investigate if the air permeability of the paper sheets (i.e. the internal structure and the surface finish of the paper) is affected when the PEC compositions were used as additives in the wet end of the paper making process, the Gurley method was used and Gurley seconds for 100 cc were determined.
Two paper sheets for each test point were measured at three different spots. The results are shown in table 14.
Table 14 shows that the Gurley is lower (air permeability is higher) for the sheets including PEC+PLA (both when compared to reference sheets and sheets containing OC-C). From this it can be concluded that the PLA particles from PEC+PLA composition make the paper sheets more porous, nevertheless both stiffer and stronger.
In the above examples it is shown that PEC can transfer the hydrophobic, mechanical and surface properties of PLA, in the particle PEC composition, to the formed paper sheets.
Materials treated with the PEC composition of the present invention need curing to develop the mechanical and hydrophobic properties meant through treatment. The curing can be done at temperatures between 20° C. and 200° C., preferably between 80° C. and 190° C., more preferably between 120° C. and 180° C. For reaching the best results, the curing temperature and time need to be optimized for each material and process.
As will be understood by those skilled in the present field of art, numerous changes and modifications may be made to the above described and other embodiments of the present invention, without departing from its scope as defined in the appending claims. For example, the pulps may be any kind of pulp, i.e. mechanical pulp, thermo-mechanical pulp, chemo-mechanical pulp, sulphate pulp, sulphite pulp, bleached pulp, unbleached pulp, short-fibre pulp, long-fibre pulp, mixtures of different pulp grades etc. The invention works irrespective of the kind of pulp chosen.
The term paperboard is here used as wide term including all kinds of different cellulose-based board grades, e.g. paper board, cardboard, corrugated board, single or multiply board, folding boxboard, chipboard etc.
While for the clarity reasons, the PEC compositions are described in the following claims only as binders for fiber based materials, textiles, woven and nonwoven materials (i.e. applied in the dry end of the process), it is equally understood that they can act as strength additives in the wet end of the process.
A various number of plasticizers may be used together with plastics known in the art without departing from the scope of the invention.
Other type of particles may be used instead of plastics such as proteins, inorganic fillers, resins, pigments.
Various aspects and embodiments of the present invention are defined by the following numbered claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1651136-2 | Aug 2016 | SE | national |
| 1651138-8 | Aug 2016 | SE | national |
This application is the continuation of International Application No. PCT/SE2017/050850, filed 24 Aug. 2017, which claims the benefit of Swedish Patent Application No. SE 1651136-2, filed 24 Aug. 2016, and Swedish Patent Application No. SE 1651138-8, filed 24 Aug. 2016, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/SE2017/050850 | Aug 2017 | US |
| Child | 16282608 | US |
