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WO2019004950A1 - High-strength sheet material - Google Patents

High-strength sheet material Download PDF

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Publication number
WO2019004950A1
WO2019004950A1 PCT/TH2017/000052 TH2017000052W WO2019004950A1 WO 2019004950 A1 WO2019004950 A1 WO 2019004950A1 TH 2017000052 W TH2017000052 W TH 2017000052W WO 2019004950 A1 WO2019004950 A1 WO 2019004950A1
Authority
WO
WIPO (PCT)
Prior art keywords
sheet material
hemicellulosic
beta
glucan
modified
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/TH2017/000052
Other languages
French (fr)
Inventor
Supakeat KAMBUTONG
Patcharin PERMPAISARNSAKUL
Kasinee THITIWUTTHISAKUL
Pattira PATTARASOPACHAI
Duangkamon BAOSUPEE
Suebthip PONGPAIBOON
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Scg Packaging Public Co Ltd
Original Assignee
Scg Packaging Public Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Scg Packaging Public Co Ltd filed Critical Scg Packaging Public Co Ltd
Priority to PCT/TH2017/000052 priority Critical patent/WO2019004950A1/en
Publication of WO2019004950A1 publication Critical patent/WO2019004950A1/en
Priority to PH12019550296A priority patent/PH12019550296A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/18—Reinforcing agents
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
    • D21H17/24—Polysaccharides
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
    • D21H23/04—Addition to the pulp; After-treatment of added substances in the pulp
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
    • D21H23/22—Addition to the formed paper

Definitions

  • strength of pulp or cellulose which is the main component of pulp which is the essential raw material in the paper and packaging industries, depends on types of wood or raw material used for producing the pulp. Apart from cellulose, lignin and hemicellulose are another main chemical constituents of wood, which could influence the strength of the paper produced. Lignin significantly glues the wood fibers together while hemicellulose helps fiber bonding which contributes to the strength of the paper. Therefore, greater strength paper could be produced if pulp having high hemicellulose content, which contributes to an increased intermolecular bonding force between cellulose and hemicellulose.
  • polysaccharides could also be employed as an additive in the current paper and packaging industries to improve paper strength, for example, to increase tensile strength, to increase toughness and to increase burst strength of the paper, etc.
  • native starch and modified starch are widely used as natural strengthening agents for paper. These natural polymers are composed of glucose units linked by a- 1,4 glycosidic bond, and they are classified in alpha-glucan polysaccharides.
  • Synthetic polymers e.g. polyamine, polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide and cationic polyacrylamide derivatives with reactive moiety are also used as strengthening agents for paper.
  • starch is used as paper strengthening agent, if used in an excessive amount, it might affect the quality of the paper product, to be precise, the obtained paper will be stiff, brittle, but tear easily. Moreover, starch is a good feed source for microbes, inadequate management may thus have effects on the paper quality as well as easy contamination of the process water.
  • hemicelluloses e.g. glucans, mannans, xylans are also currently used.
  • CA 2316894 Al discloses a polysaccharide complex with an attached entity capable of binding cellulose.
  • the attached entity has a molecular weight of at least 5,000 g/mole and has a glucan backbone, a mannan backbone or a xylan backbone.
  • Said polysaccharide complex binds to a proximity to the cellulose surface or to a cellulose-containing substance.
  • the polysaccharide complex is used in cotton fiber material, textile material and paper pulp material, etc.
  • the polysaccharide complex can be comprised in products for textile such as textile cleaning and conditioning agents, in which case, the attached entity of the polysaccharide complex may be modified with enzyme or fragrance-binding particles.
  • US20040091977A1 discloses a method for adding chemical functional groups onto the surface of the polymeric carbohydrate material in order to alter the physio-chemical properties using linking molecular carbohydrate having chemical functional groups with specialized properties.
  • Chemically-modified oligosaccharides are introduced into a carbohydrate polymer using a transglycosylating enzyme.
  • Said Unking molecular carbohydrate is capable of binding to the polymeric carbohydrate material to provide a desired functionality. It can be used in the process for producing pulp sheet material and paper board as well as used as reinforcing additive for liquid and food packaging.
  • the introduction of chemical functional groups onto the carbohydrate polymer by this method do not affect the fiber structure and increases the binding force between polymer and fiber in the material.
  • EP 2246472 A 1 discloses a process for preparing polysaccharide gel and pulp furnish for use in paper making. Said process involves the preparation of a bulk gel of polysaccharide dispersion for use in the production of pulp sheet material and paper board, said polysaccharide gel is polydispersed or modified to have better particle size dispersion.
  • the polysaccharide gel is used for improving the properties of the pulp sheet material and the paper board to increase bursting strength, tensile strength, stiffness and folding strength.
  • the gel particles of said polysaccharide can be prepared by direct linkage of molecule or linkage via cation and anion.
  • WO 2007149045 Bl discloses a carbohydrate polymer which is modified into copolymer and the method of preparation thereof.
  • the method for preparing said copolymer is carried out by adding a novel functional group in a group of soluble carbohydrates (usually excluding starch carbohydrate) to polymer macromolecule covalently attached thereto.
  • Said polymer macromolecule may be hydrophobic copolymer, polyelectrolyte polymer or biodegradable polymer.
  • Said copolymer may be used in composite materials for use as packaging such as food packaging and liquid packaging, or in plywood formed of fiber or fine wood scraps, laminates prepared from pulp sheets or paper board, for example.
  • Said copolymer can be used to improve the properties of the fiber due to its ability to form a bond with the anion on the surface of the material, and functions as retention aid for fiber and powdered mineral filler in the pulp sheet manufacturing process.
  • the present invention relates to a high-strength sheet material comprising (a) cellulose or cellulosic material; and (b) an additive comprising chemically modified hemicellulosic beta- glucan selected from cationically modified hemicellulosic beta-glucan, anionically modified hemicellulosic beta-glucan, amphoterically modified hemicellulosic beta-glucan or a mixture of at least two of said chemically modified hemicellulosic beta-glucans.
  • the high-strength sheet material according to the present invention further comprises a crosslinking agents forming one or more network structures selected from a network of cellulose, a network of chemically modified hemicellulosic beta-glucans or a network of cellulose and chemically modified hemicellulosic beta-glucans.
  • the object of the present invention is to provide a high-strength sheet material yielding technical advantages, that is the high-strength sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention has increased strength and flexibility.
  • Tensile index, burst index, tensile energy absorption (TEA), flat crush resistance of corrugating medium (Corrugating Medium Test, CMT), stretching and short span compression resistance (Short Span Compression Test, SCT) of the sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention are greater compared to the sheet material without any additive and the sheet material comprising other additives used as strengthening agents.
  • the sheet material comprising chemically modified hemicellulosic beta- glucan according to the present invention achieves reduced freeness but does not increase drainage time in the production process, thus does not require more production time and does not affect the gross yield per time unit compared to the sheet material containing other additives such as starch, modified starch, polyacrylamide, etc.
  • Fig. 1 shows the molecular structure of the chemically modified hemicellulosic beta- glucan according to the present invention.
  • Fig. 2 shows the network structure of the cellulose and the chemically modified hemicellulosic beta-glucan according to the present invention.
  • Fig.3a is a graph showing the test results for burst index and tensile strength index of the high-strength sheet material according to the present invention.
  • Fig.3b is a graph showing the test results for burst index and tensile strength index of the sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
  • Fig.4a is a graph showing the test results for tensile energy absorption and tensile strength index of the high-strength sheet material according to the present invention.
  • Fig.4b is a graph showing the test results for tensile energy absorption and tensile strength index of the high-strength sheet material according to the present invention in comparison to the sheet material comprising other commercial additives.
  • Fig. sais a graph showing the test results for short span compression resistance index and tensile strength index of the high-strength sheet material according to the present invention.
  • Fig.5b is a graph showing the test results for short span compression resistance index and tensile strength index of the high-strength sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
  • Fig. 6 a is a graph showing the test results for ring crush resistance and tensile strength index of the high-strength sheet material according to the present invention.
  • Fig. 6b is a graph showing the test results for ring crush resistance and tensile strength index of the high-strength sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
  • Fig.7a is a graph showing the test results for flat crush resistance of corrugating medium and tensile strength index of the high-strength sheet material according to the present invention.
  • Fig.7b is a graph showing the test results for flat crush resistance of corrugating medium and tensile strength index of the high-strength sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
  • Fig. 8 a is a graph showing the test results for stretching and tensile strength index of the high-strength sheet material according to the present invention.
  • Fig. 8b is a graph showing the test results for stretching and tensile strength index of the high-strength sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
  • Fig. 9 is a graph showing the test results for plybond strength of the sheet material and tensile strength index of the high-strength sheet material according to the present invention.
  • Fig. 10 is a graph showing the test results for draining time and freenage during the process for producing the sheet material.
  • the high-strength sheet material comprises:
  • an additive comprising chemically modified hemicellulosic beta-glucan selected from cationically modified hemicellulosic beta-glucan, anionically modified hemicellulosic beta- glucan, amphoterically modified hemicellulosic beta-glucan or a mixture of at least two of said chemically modified hemicellulosic beta-glucans.
  • the preferred additive according to the present invention comprises chemically modified hemicellulosic beta-glucan selected from cationically modified hemicellulosic beta-glucan, amphoterically modified hemicellulosic beta-glucan or a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan.
  • the additive is present in a range of o.1-4.0% by weight of the dry pulp, preferably 1-2% by weight of the dry pulp.
  • cationically modified hemicellulosic beta-glucan is a hemicellulosic beta-glucan chemically modified with functional group selected from amino group, imino group, ammonium group, sulfonate group, phosphonate group or at least two of said functional groups.
  • the preferred cationically modified hemicellulosic beta-glucan according to the present invention is a hemicellulosic beta-glucan that is chemically modified with ammonium group.
  • the cationically modified hemicellulosic beta-glucan chemically modified with ammonium group has a nitrogen content in a range of 0.05-0.50% by weight, preferably has a nitrogen in a range of o.io-o.3o%by weight.
  • the anionically modified hemicellulosic beta-glucan is a hemicellulosic beta-glucan that is chemically modified with functional groups selected from carboxylate group, sulphate group, phosphate group or at least two of said functional groups.
  • the preferred anionically modified hemicellulosic beta-glucan according to the present invention is a hemicellulosic beta-glucan that is chemically modified with carboxylate group.
  • the hemicellulosic beta-glucan chemically modified with carboxylate group according to the present invention has a carboxyl content in a range of 1.0 10.0% by weight, preferably has a carboxyl in a range of 2.0-5.0% by weight.
  • the nitrogen content and the carboxyl content mentioned above is in percent by weight based on the total weight of the chemically modified hemicellulosic beta-glucan that is chemically modified with ammonium group and carboxylate group, respectively.
  • a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan is obtained from combining (i) hemicellulosic beta-glucan chemically modified with functional groups selected from amino group, imino group, ammonium group, sulfonate group, phosphonate group or at least two of said functional groups; and (ii) hemicellulosic beta-glucan chemically modified with functional groups selected from carboxylate group, sulphate group, phosphate group or at least two of said functional groups.
  • the chemically modified hemicellulosic beta-glucan can also be obtained by modifying the hemicellulosic beta-glucan with functional groups selected from ketone group, ester group, ether group, aldehyde group, amide group or at least two of said functional groups.
  • the preferred mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan according to the present invention is a mixture of cationically modified hemicellulosic beta-glucan chemically modified with ammonium group and hemicellulosic beta-glucan chemically modified with carboxylate group.
  • the amphoterically modified hemicellulosic beta- glucan is a hemicellulosic beta-glucan chemically modified with two functional groups consisting of one from the amino group, imino group, or ammonium group, and the other is from the group consisting of sulfonate group, phosphonate group, carboxylate group, sulphate group or phosphate group.
  • the preferred amphoterically modified hemicellulosic beta-glucan according to the present invention is hemicellulosic beta-glucan that is chemically modified with ammonium group and carboxylate group.
  • the hemicellulosic beta-glucan chemically modified with ammonium group and carboxylate group according to the present invention has a total particle charge demand in a range of 20-2,000 ⁇ /g.
  • chemically modified hemicellulosic beta-glucan is obtained from a reaction selected from condensation reaction, esterification reaction, etherifi cation reaction or a combination of esterification reaction and etherification reaction.
  • the preferred chemically modified hemicellulosic beta-glucan according to the present invention is obtained by etherification reaction.
  • the chemically modified hemicellulosic beta-glucan according to the present invention may also adhere well to the surface of cellulose by ionic bond and thereby enhancing the bonding to cellulose.
  • the chemically modified hemicellulosic beta-glucan according to the present invention can be used as additive to reinforce the sheet material made from either recycled or non-recycled pulp or cellulose.
  • the molecular structure of the chemically modified hemicellulosic beta-glucan according to the present invention is shown in Fig. 1.
  • hemicellulosic beta-glucan is obtained from raw materials selected from clubmosses, ferns, gymnosperm plants, angiosperm plants, or a mixture of two of said raw materials.
  • the hemicellulosic beta-glucan obtained from said raw material is subjected to chemical modification with the aforementioned-functional groups prior to be used as additive in the sheet material according to the present invention.
  • the chemically modified hemicellulosic beta-glucan according to the present invention can mediate the linkage, thereby forming a network within the sheet material imparting an increased strength and flexibility to the sheet material.
  • Such network structure can be formed using a crosslinking agent, said crosslinking agent being reactive to form a network linkage between molecules within the sheet material, especially between the cellulose molecules and the chemically modified hemicellulosic beta-glucans as shown in Fig.2.
  • the high-strength sheet material further comprises a crosslinking agent forming one or more network structures selected from a network of cellulose, a network of chemically modified hemicellulosic beta-glucans or a network of cellulose and chemically modified hemicellulosic beta-glucans.
  • the crosslinking agent according to the present invention is an inorganic compound selected from metal carbonate salt, metal borate salt, metal sulfate salt, metal phosphate salt or a mixture of at least two of said metal salts.
  • the preferred crosslinking agent according to the present invention is metal borate salt, more preferably sodium borate.
  • the high-strength sheet material according to the present invention has a crosslinking agent content in a range of 0.025- 1.0% by weight, preferably in a range of 0.25-0.5% by weight.
  • cellulose is selected from unbleached chemical pulp, unbleached semi-chemical pulp, bleached chemical pulp, waste paper pulp, recycled pulp or a mixture of at least two of said pulp.
  • the high-strength sheet material is printing and writing paper, food packaging paper or paper for packaging industry.
  • the high-strength sheet material is obtained from the method for producing sheet material comprising the steps selected from applying a wet end additive, applying an additive for sizing, applying an additive for spraying or a combination of at least two of said steps.
  • the method for producing the high-strength sheet material according to the present invention preferably comprises the step of applying a wet end additive.
  • the step of applying an additive in the above method for producing sheet material comprises adding an additive comprising hemicellulosic beta- glucan that is chemically modified to react with and to bond to the cellulose fiber surface.
  • said method for producing the high-strength sheet material further comprises the step of adding a crosslinking agent to form a network structure
  • the formed network structure may be at least one or more selected from a network of cellulose, a network of chemically modified hemicellulosic beta-glucans or a network of cellulose and chemically modified hemicellulosic beta-glucans.
  • the high-strength sheet material according to the present invention may preferably be obtained by the method for producing the sheet material comprising the steps of applying a wet end additive. Furthermore, the high-strength sheet material according to the present invention may preferably be obtained from the method for producing the sheet material comprising the step of applying a wet end additive in combination with the step of adding a crosslinking agent.
  • the high-strength sheet material according to the present invention has key features, namely the components, the content of the components and various aspects imparting the above technical advantages.
  • the high-strength sheet material according to the present invention is not limited to said aspects.
  • Various variations and modifications can be made to such aspects such that they yield similar technical advantages which are considered within the spirit and the scope of the present invention.
  • a physical property test was conducted on sheet material samples containing different additives and a reference sheet material to determine burst index on the basis of the standard ISO 2758, 2759.2001 , and tensile index, stretching of the paper, tensile energy absorption (TEA) on the basis of the test standard ISO 1924-2:2008, short span compression resistance ( SCT) on the basis of the test standard ISO 9895:1989, ring crush resistance (RCT) on the basis of the test standard ISO 12192:2002, Corrugating Medium Test
  • CMT on the basis of the test standard Tappi:T 824 om-02, and plybond strength of the sheet material , including to determine drainage during the process for producing the sheet material.
  • the test was conducted on the sheet material samples comprising chemically modified hemicellulosic beta-glucan additives i.e. cationically modified hemicellulosic beta-glucan (in an amount of 1% and 2% by weight), amphotencally modified hemicellulosic beta-glucan (in an amount of 1% and 2% by weight), and a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan (in an amount of 1 % and 2% by weight) together with borax (in an amount of 0.25% and 0.5% by weight) for the purpose of comparing to the reference sheet material (additive-free sheet material).
  • chemically modified hemicellulosic beta-glucan additives i.e. cationically modified hemicellulosic beta-glucan (in an amount of 1% and 2% by weight), amphotencally modified hemicellulosic beta
  • the test was conducted on the sheet materials comprising other additives such as native hemicellulosic beta-glucan (in an amount of 1% and 2% by weight), commercial cationically modified starch (in an amount of 1 % and 2% by weight), commercial amphoterically modified starch (in an amount of 1 % and 2% by weight) and commercial amphoterically modified starch (in an amount of 1 % and 2% by weight) for additional comparison.
  • additives such as native hemicellulosic beta-glucan (in an amount of 1% and 2% by weight), commercial cationically modified starch (in an amount of 1 % and 2% by weight), commercial amphoterically modified starch (in an amount of 1 % and 2% by weight) and commercial amphoterically modified starch (in an amount of 1 % and 2% by weight) for additional comparison.
  • the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile index by 20% and 23%, respectively and an increase in burst index by 21 % and 37%, respectively;
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile index by 23% and 22%, respectively and an increase in burst index by 23% and 41%, respectively;
  • the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded tensile index by 25% and 29%, respectively and an increase in burst index by 28% and 44%, respectively.
  • the tensile index was increased by 13% and burst index increased by 25% (compared to the test results obtained from the reference sheet material).
  • the results are as shown in Fig.3b.
  • burst index decreased by 3% and 10%, respectively ⁇ compared to the test results obtained from the reference sheet material).
  • the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile energy absorption of the sheet material by 22% and 53%, respectively;
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile energy absorption of the sheet material by 43% and 89%, respectively;
  • the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile energy absorption of the sheet material by 46% and 60%, respectively.
  • the sheet material comprising amphoterically modified hemicellulosic beta-glucan had an increase in tensile energy absorption by 47% and the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan had an increase in tensile energy absorption by 43% (compared to the test results obtained from the reference sheet material).
  • the results are as shown in Fig.4b.
  • test results show that sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention yielded a significant increase in short span compression resistance index compared to the reference sheet material as follows:
  • the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in short span compression resistance index by 13% and 14%, respectively;
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in short span compression resistance index by 10% and 18%, respectively;
  • the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1 % and 2% by weight yielded an increase in short span compression resistance index by 13% and 22%, respectively.
  • the sheet material comprising amphoterically modified hemicellulosic beta-glucan had an increase in short span compression resistance index by 13% and the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan had an increase in short span compression resistance index by 10% (compared to the test results obtained from the reference sheet material)
  • the results are as shown in Fig. 5b.
  • the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of the sheet material by 14% and 21 %, respectively;
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of the sheet material by 13% and 20%, respectively; and -the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1 % and 2% by weight yielded an increase in ring crush resistance of the sheet material by 16% and 23%, respectively.
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in ring crush resistance by 13% and 20%, respectively and the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in ring crush resistance by 16% and 23%, respectively (compared to the test results obtained from the reference sheet material) The results are as shown in Fig.6b.
  • the sheet material comprising commercial cationically modified starch in an amount of 1% and 2% by weight resulted in a decrease in ring crush resistance by 6% and an increase by 2%, respectively and that the sheet material comprising commercial amphoterically modified starch in an amount of 1% and 2% by weight resulted in a decrease in ring crush resistance by 8% and an increase by 8%, respectively (compared to the test results obtained from the reference sheet material).
  • test results show that sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention yielded a significant increase in ring crush resistance of corrugating medium of the sheet material compared to the reference sheet material as follows: - the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of corrugating medium of the sheet material by 25% and 30%, respectively;
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of corrugating medium of the sheet material by 28% and 38%, respectively, and
  • the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of corrugating medium of the sheet material by 27% and 39%, respectively.
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in ring crush resistance of corrugating medium by 28% and 38%, respectively and that the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase ring crush resistance of corrugating medium by 27% and 39%, respectively (compared to the test results obtained from the reference sheet material). The results are as shown in Fig. 7b.
  • the sheet material comprising commercial cationic starch in an amount of 1% and 2% by weight resulted in a decrease in ring crush resistance by 2% and an increase by 9%, respectively and that the sheet material comprising commercial amphoterically modified starch in an amount of 1% and 2% by weight resulted in an increase in ring crush resistance by only 4% and 16%, respectively (compared to the test results obtained from the reference sheet material).
  • the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in stretching of the sheet material by 16% and 25%, respectively;
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in stretching of the sheet material by 17% and 61 %, respectively;
  • the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in stretching of the sheet material by 18% and 26%, respectively.
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in stretching by 17% and 61%, respectively and that the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in stretching by 18% and 26%, respectively (compared to the test results obtained from the reference sheet material).
  • the results are as shown in Fig.8b.
  • the sheet material comprising commercial cationically modified starch in an amount of 1% and 2% by weight resulted in an increase in stretching by only 6% and 17%, respectively (compared to the test results obtained from the reference sheet material) and that the sheet material comprising commercial amphoterically modified starch was unable to increase the stretching of the sheet material while polyacrylamide cannot be used in an amount of 2% by weight because it causes the pulp to aggregate making it unable to be formed as sheet paper.
  • the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in plybond strength of the sheet material by 18% and 29%, respectively.
  • the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in plybond strength of the sheet material by 13% and 32%, respectively;
  • the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1 % and 2% by weight yielded an increase in plybond strength of the sheet material by 16% and 25%, respectively.
  • the test results show that for the sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention, the average process draining time was approximately 7 seconds which is not different from the reference sheet material. Considering the test results further, it was found that using natural hemicellulosic beta-glucan or chemically modified hemicellulosic beta-glucan according to the present invention as additive resulted in a decrease in freeness from 250 ml to 100 - 180 ml but the draining time was not affected compared to the using starch and polyacrylamide as additives. The results are as shown in Fig. 10.

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Abstract

The present invention relates to a high-strength sheet material comprising: (a) cellulose or cellulosic material; and (b) an additive comprising chemically modified hemicellulosic beta- glucan selected from cationically modified hemicellulosic beta-glucan, anionically modified hemicellulosic beta-glucan, amphoterically modified hemicellulosic beta-glucan or a mixture of at least two of said chemically modified hemicellulosic beta-glucans. According to the present invention, said high-strength sheet material further comprises a crosslinking agent forming one or more network structures selected from a network of cellulose, a network of chemically modified hemicellulosic beta-glucans, or a network of cellulose and chemically modified hemicellulosic beta-glucans.

Description

TITLE OF THE INVENTION
High-strength sheet material
FIELD OF THE INVENTION
Chemistry related to high-strength sheet material
BACKGROUND OF THE INVENTION
Generally, strength of pulp or cellulose, which is the main component of pulp which is the essential raw material in the paper and packaging industries, depends on types of wood or raw material used for producing the pulp. Apart from cellulose, lignin and hemicellulose are another main chemical constituents of wood, which could influence the strength of the paper produced. Lignin significantly glues the wood fibers together while hemicellulose helps fiber bonding which contributes to the strength of the paper. Therefore, greater strength paper could be produced if pulp having high hemicellulose content, which contributes to an increased intermolecular bonding force between cellulose and hemicellulose. Other polysaccharides could also be employed as an additive in the current paper and packaging industries to improve paper strength, for example, to increase tensile strength, to increase toughness and to increase burst strength of the paper, etc. More specifically, native starch and modified starch are widely used as natural strengthening agents for paper. These natural polymers are composed of glucose units linked by a- 1,4 glycosidic bond, and they are classified in alpha-glucan polysaccharides. Synthetic polymers e.g. polyamine, polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide and cationic polyacrylamide derivatives with reactive moiety are also used as strengthening agents for paper.
However, using the above strengthening agents might lead to issues in certain cases. For example, in the case where starch is used as paper strengthening agent, if used in an excessive amount, it might affect the quality of the paper product, to be precise, the obtained paper will be stiff, brittle, but tear easily. Moreover, starch is a good feed source for microbes, inadequate management may thus have effects on the paper quality as well as easy contamination of the process water.
Other than the above additives used as strengthening agents, natural substance capable of forming good hydrogen bond with cellulose, as referred to hemicelluloses e.g. glucans, mannans, xylans are also currently used.
Examples of prior arts disclosing the inventions related to compositions or materials comprising hemicellulosic beta-glucan and production methods thereof are as listed below. CA 2316894 Al discloses a polysaccharide complex with an attached entity capable of binding cellulose. The attached entity has a molecular weight of at least 5,000 g/mole and has a glucan backbone, a mannan backbone or a xylan backbone. Said polysaccharide complex binds to a proximity to the cellulose surface or to a cellulose-containing substance. The polysaccharide complex is used in cotton fiber material, textile material and paper pulp material, etc. Furthermore, the polysaccharide complex can be comprised in products for textile such as textile cleaning and conditioning agents, in which case, the attached entity of the polysaccharide complex may be modified with enzyme or fragrance-binding particles.
US20040091977A1 discloses a method for adding chemical functional groups onto the surface of the polymeric carbohydrate material in order to alter the physio-chemical properties using linking molecular carbohydrate having chemical functional groups with specialized properties. Chemically-modified oligosaccharides are introduced into a carbohydrate polymer using a transglycosylating enzyme. Said Unking molecular carbohydrate is capable of binding to the polymeric carbohydrate material to provide a desired functionality. It can be used in the process for producing pulp sheet material and paper board as well as used as reinforcing additive for liquid and food packaging. The introduction of chemical functional groups onto the carbohydrate polymer by this method do not affect the fiber structure and increases the binding force between polymer and fiber in the material.
EP 2246472 A 1 discloses a process for preparing polysaccharide gel and pulp furnish for use in paper making. Said process involves the preparation of a bulk gel of polysaccharide dispersion for use in the production of pulp sheet material and paper board, said polysaccharide gel is polydispersed or modified to have better particle size dispersion. The polysaccharide gel is used for improving the properties of the pulp sheet material and the paper board to increase bursting strength, tensile strength, stiffness and folding strength. The gel particles of said polysaccharide can be prepared by direct linkage of molecule or linkage via cation and anion.
WO 2007149045 Bl discloses a carbohydrate polymer which is modified into copolymer and the method of preparation thereof. The method for preparing said copolymer is carried out by adding a novel functional group in a group of soluble carbohydrates (usually excluding starch carbohydrate) to polymer macromolecule covalently attached thereto. Said polymer macromolecule may be hydrophobic copolymer, polyelectrolyte polymer or biodegradable polymer. Said copolymer may be used in composite materials for use as packaging such as food packaging and liquid packaging, or in plywood formed of fiber or fine wood scraps, laminates prepared from pulp sheets or paper board, for example. Said copolymer can be used to improve the properties of the fiber due to its ability to form a bond with the anion on the surface of the material, and functions as retention aid for fiber and powdered mineral filler in the pulp sheet manufacturing process. SUMMARY OF THE INVENTION
The present invention relates to a high-strength sheet material comprising (a) cellulose or cellulosic material; and (b) an additive comprising chemically modified hemicellulosic beta- glucan selected from cationically modified hemicellulosic beta-glucan, anionically modified hemicellulosic beta-glucan, amphoterically modified hemicellulosic beta-glucan or a mixture of at least two of said chemically modified hemicellulosic beta-glucans. Further, the high-strength sheet material according to the present invention further comprises a crosslinking agents forming one or more network structures selected from a network of cellulose, a network of chemically modified hemicellulosic beta-glucans or a network of cellulose and chemically modified hemicellulosic beta-glucans.
The object of the present invention is to provide a high-strength sheet material yielding technical advantages, that is the high-strength sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention has increased strength and flexibility. Tensile index, burst index, tensile energy absorption (TEA), flat crush resistance of corrugating medium (Corrugating Medium Test, CMT), stretching and short span compression resistance (Short Span Compression Test, SCT) of the sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention are greater compared to the sheet material without any additive and the sheet material comprising other additives used as strengthening agents.
Moreover, the sheet material comprising chemically modified hemicellulosic beta- glucan according to the present invention achieves reduced freeness but does not increase drainage time in the production process, thus does not require more production time and does not affect the gross yield per time unit compared to the sheet material containing other additives such as starch, modified starch, polyacrylamide, etc.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows the molecular structure of the chemically modified hemicellulosic beta- glucan according to the present invention. Fig. 2 shows the network structure of the cellulose and the chemically modified hemicellulosic beta-glucan according to the present invention.
Fig.3a is a graph showing the test results for burst index and tensile strength index of the high-strength sheet material according to the present invention.
Fig.3b is a graph showing the test results for burst index and tensile strength index of the sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
Fig.4a is a graph showing the test results for tensile energy absorption and tensile strength index of the high-strength sheet material according to the present invention.
Fig.4b is a graph showing the test results for tensile energy absorption and tensile strength index of the high-strength sheet material according to the present invention in comparison to the sheet material comprising other commercial additives.
Fig. sais a graph showing the test results for short span compression resistance index and tensile strength index of the high-strength sheet material according to the present invention.
Fig.5b is a graph showing the test results for short span compression resistance index and tensile strength index of the high-strength sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
Fig. 6 a is a graph showing the test results for ring crush resistance and tensile strength index of the high-strength sheet material according to the present invention.
Fig. 6b is a graph showing the test results for ring crush resistance and tensile strength index of the high-strength sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
Fig.7a is a graph showing the test results for flat crush resistance of corrugating medium and tensile strength index of the high-strength sheet material according to the present invention.
Fig.7b is a graph showing the test results for flat crush resistance of corrugating medium and tensile strength index of the high-strength sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
Fig. 8 a is a graph showing the test results for stretching and tensile strength index of the high-strength sheet material according to the present invention. Fig. 8b is a graph showing the test results for stretching and tensile strength index of the high-strength sheet material according to the present invention in comparison with the sheet material comprising other commercial additives.
Fig. 9 is a graph showing the test results for plybond strength of the sheet material and tensile strength index of the high-strength sheet material according to the present invention.
Fig. 10 is a graph showing the test results for draining time and freenage during the process for producing the sheet material.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described in further detail.
According to the present invention, the high-strength sheet material comprises:
(a) cellulose or cellulosic material; and
(b) an additive comprising chemically modified hemicellulosic beta-glucan selected from cationically modified hemicellulosic beta-glucan, anionically modified hemicellulosic beta- glucan, amphoterically modified hemicellulosic beta-glucan or a mixture of at least two of said chemically modified hemicellulosic beta-glucans.
The preferred additive according to the present invention comprises chemically modified hemicellulosic beta-glucan selected from cationically modified hemicellulosic beta-glucan, amphoterically modified hemicellulosic beta-glucan or a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan.
According to the present invention, the additive is present in a range of o.1-4.0% by weight of the dry pulp, preferably 1-2% by weight of the dry pulp.
According to the present invention, cationically modified hemicellulosic beta-glucan is a hemicellulosic beta-glucan chemically modified with functional group selected from amino group, imino group, ammonium group, sulfonate group, phosphonate group or at least two of said functional groups.
The preferred cationically modified hemicellulosic beta-glucan according to the present invention is a hemicellulosic beta-glucan that is chemically modified with ammonium group.
The cationically modified hemicellulosic beta-glucan chemically modified with ammonium group according to the present invention has a nitrogen content in a range of 0.05-0.50% by weight, preferably has a nitrogen in a range of o.io-o.3o%by weight. According to the present invention, the anionically modified hemicellulosic beta-glucan is a hemicellulosic beta-glucan that is chemically modified with functional groups selected from carboxylate group, sulphate group, phosphate group or at least two of said functional groups.
The preferred anionically modified hemicellulosic beta-glucan according to the present invention is a hemicellulosic beta-glucan that is chemically modified with carboxylate group.
The hemicellulosic beta-glucan chemically modified with carboxylate group according to the present invention has a carboxyl content in a range of 1.0 10.0% by weight, preferably has a carboxyl in a range of 2.0-5.0% by weight.
According to the present invention, the nitrogen content and the carboxyl content mentioned above is in percent by weight based on the total weight of the chemically modified hemicellulosic beta-glucan that is chemically modified with ammonium group and carboxylate group, respectively.
According to the present invention, a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan is obtained from combining (i) hemicellulosic beta-glucan chemically modified with functional groups selected from amino group, imino group, ammonium group, sulfonate group, phosphonate group or at least two of said functional groups; and (ii) hemicellulosic beta-glucan chemically modified with functional groups selected from carboxylate group, sulphate group, phosphate group or at least two of said functional groups.
According to the present invention, the chemically modified hemicellulosic beta-glucan can also be obtained by modifying the hemicellulosic beta-glucan with functional groups selected from ketone group, ester group, ether group, aldehyde group, amide group or at least two of said functional groups.
The preferred mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan according to the present invention is a mixture of cationically modified hemicellulosic beta-glucan chemically modified with ammonium group and hemicellulosic beta-glucan chemically modified with carboxylate group.
According to the present invention, the amphoterically modified hemicellulosic beta- glucan is a hemicellulosic beta-glucan chemically modified with two functional groups consisting of one from the amino group, imino group, or ammonium group, and the other is from the group consisting of sulfonate group, phosphonate group, carboxylate group, sulphate group or phosphate group. The preferred amphoterically modified hemicellulosic beta-glucan according to the present invention is hemicellulosic beta-glucan that is chemically modified with ammonium group and carboxylate group.
The hemicellulosic beta-glucan chemically modified with ammonium group and carboxylate group according to the present invention has a total particle charge demand in a range of 20-2,000 μβς/g.
According to the present invention, chemically modified hemicellulosic beta-glucan is obtained from a reaction selected from condensation reaction, esterification reaction, etherifi cation reaction or a combination of esterification reaction and etherification reaction.
The preferred chemically modified hemicellulosic beta-glucan according to the present invention is obtained by etherification reaction.
In addition to its ability to adhere to the surface of cellulose by hydrogen bond, the chemically modified hemicellulosic beta-glucan according to the present invention may also adhere well to the surface of cellulose by ionic bond and thereby enhancing the bonding to cellulose. The chemically modified hemicellulosic beta-glucan according to the present invention can be used as additive to reinforce the sheet material made from either recycled or non-recycled pulp or cellulose. The molecular structure of the chemically modified hemicellulosic beta-glucan according to the present invention is shown in Fig. 1.
According to the present invention, hemicellulosic beta-glucan is obtained from raw materials selected from clubmosses, ferns, gymnosperm plants, angiosperm plants, or a mixture of two of said raw materials. The hemicellulosic beta-glucan obtained from said raw material is subjected to chemical modification with the aforementioned-functional groups prior to be used as additive in the sheet material according to the present invention.
Since the adhesion to the surface of cellulose by the chemically modified hemicellulosic beta-glucan according to the present invention is achieved by hydrogen bond and/or the force between charges of two molecules, the chemically modified hemicellulosic beta-glucan according to the present invention can mediate the linkage, thereby forming a network within the sheet material imparting an increased strength and flexibility to the sheet material.
Such network structure can be formed using a crosslinking agent, said crosslinking agent being reactive to form a network linkage between molecules within the sheet material, especially between the cellulose molecules and the chemically modified hemicellulosic beta-glucans as shown in Fig.2. According to the present invention, the high-strength sheet material further comprises a crosslinking agent forming one or more network structures selected from a network of cellulose, a network of chemically modified hemicellulosic beta-glucans or a network of cellulose and chemically modified hemicellulosic beta-glucans.
The crosslinking agent according to the present invention is an inorganic compound selected from metal carbonate salt, metal borate salt, metal sulfate salt, metal phosphate salt or a mixture of at least two of said metal salts.
The preferred crosslinking agent according to the present invention is metal borate salt, more preferably sodium borate.
The high-strength sheet material according to the present invention has a crosslinking agent content in a range of 0.025- 1.0% by weight, preferably in a range of 0.25-0.5% by weight.
According to the present invention, cellulose is selected from unbleached chemical pulp, unbleached semi-chemical pulp, bleached chemical pulp, waste paper pulp, recycled pulp or a mixture of at least two of said pulp.
According to the present invention, the high-strength sheet material is printing and writing paper, food packaging paper or paper for packaging industry.
According to the present invention, the high-strength sheet material is obtained from the method for producing sheet material comprising the steps selected from applying a wet end additive, applying an additive for sizing, applying an additive for spraying or a combination of at least two of said steps.
The method for producing the high-strength sheet material according to the present invention preferably comprises the step of applying a wet end additive.
According to the present invention, the step of applying an additive in the above method for producing sheet material comprises adding an additive comprising hemicellulosic beta- glucan that is chemically modified to react with and to bond to the cellulose fiber surface.
According to the present invention, said method for producing the high-strength sheet material further comprises the step of adding a crosslinking agent to form a network structure, the formed network structure may be at least one or more selected from a network of cellulose, a network of chemically modified hemicellulosic beta-glucans or a network of cellulose and chemically modified hemicellulosic beta-glucans.
The high-strength sheet material according to the present invention may preferably be obtained by the method for producing the sheet material comprising the steps of applying a wet end additive. Furthermore, the high-strength sheet material according to the present invention may preferably be obtained from the method for producing the sheet material comprising the step of applying a wet end additive in combination with the step of adding a crosslinking agent.
As described above, the high-strength sheet material according to the present invention has key features, namely the components, the content of the components and various aspects imparting the above technical advantages. However, the high-strength sheet material according to the present invention is not limited to said aspects. Various variations and modifications can be made to such aspects such that they yield similar technical advantages which are considered within the spirit and the scope of the present invention.
The present invention will now be described in further detail by way of examples.
However, it should be understood that the following examples do not limit the scope of the present invention.
According to the present invention, a physical property test was conducted on sheet material samples containing different additives and a reference sheet material to determine burst index on the basis of the standard ISO 2758, 2759.2001 , and tensile index, stretching of the paper, tensile energy absorption (TEA) on the basis of the test standard ISO 1924-2:2008, short span compression resistance ( SCT) on the basis of the test standard ISO 9895:1989, ring crush resistance (RCT) on the basis of the test standard ISO 12192:2002, Corrugating Medium Test
(CMT) on the basis of the test standard Tappi:T 824 om-02, and plybond strength of the sheet material , including to determine drainage during the process for producing the sheet material.
According to the present invention, the test was conducted on the sheet material samples comprising chemically modified hemicellulosic beta-glucan additives i.e. cationically modified hemicellulosic beta-glucan (in an amount of 1% and 2% by weight), amphotencally modified hemicellulosic beta-glucan (in an amount of 1% and 2% by weight), and a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan (in an amount of 1 % and 2% by weight) together with borax (in an amount of 0.25% and 0.5% by weight) for the purpose of comparing to the reference sheet material (additive-free sheet material).
Furthermore, the test was conducted on the sheet materials comprising other additives such as native hemicellulosic beta-glucan (in an amount of 1% and 2% by weight), commercial cationically modified starch (in an amount of 1 % and 2% by weight), commercial amphoterically modified starch (in an amount of 1 % and 2% by weight) and commercial amphoterically modified starch (in an amount of 1 % and 2% by weight) for additional comparison.
Examples
1. Comparison between tensile index and burst index
The test results show that the sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention yields a significant increase in tensile index and burst index compared to the reference sheet material as follows:
- the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile index by 20% and 23%, respectively and an increase in burst index by 21 % and 37%, respectively;
- the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile index by 23% and 22%, respectively and an increase in burst index by 23% and 41%, respectively; and
- the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded tensile index by 25% and 29%, respectively and an increase in burst index by 28% and 44%, respectively.
While the sheet material comprising native hemicellulosic beta-glucan ( natural hemicellulosic beta-glucan) yielded an increase in tensile index by 13% and 23%, respectively and an increase in burst index by 15% and 29%, respectively. The results are as shown in Fig. 3a.
Comparing the results of the test conducted on the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% by weight and the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% by weight to the sheet material comprising other additives, it is found that when amphoterically modified hemicellulosic beta-glucan was used as strengthening agent, the resulting sheet material had a significantly greater tensile index and burst index than when other additives were used. To be precise, the tensile index was increased by 13% and burst index increased by 25% (compared to the test results obtained from the reference sheet material). The results are as shown in Fig.3b. Moreover, it is found that using the commercial cationically modified starch and the commercial amphoterically modified starch as additives in the sheet material (1% by weight) resulted in a decrease in tensile index by 5% and 6%, respectively. Also, burst index decreased by 3% and 10%, respectively {compared to the test results obtained from the reference sheet material).
2. Comparison of tensile energy absorption of the sheet materials
The test results show that the sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention yielded a significantly increased in tensile energy absorption of the sheet material compared to the reference sheet material as follows:
- the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile energy absorption of the sheet material by 22% and 53%, respectively;
- the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile energy absorption of the sheet material by 43% and 89%, respectively; and
-the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in tensile energy absorption of the sheet material by 46% and 60%, respectively.
While the sheet material comprising native hemicellulosic beta-glucan ( natural hemicellulosic beta-glucan) in an amount of 1% and 2% by weight yielded an increase in tensile energy absorption of the sheet material by 17% and 46%, respectively. The results are as shown in Fig.4a.
Comparing the test results obtained from the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% by weight and the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% by weight to the sheet material comprising other additives, it is found that using said two chemically modified hemicellulosic beta-glucans as additives, the resulting sheet material had a significantly greater tensile energy absorption than when using other additives. To be precise, the sheet material comprising amphoterically modified hemicellulosic beta-glucan had an increase in tensile energy absorption by 47% and the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan had an increase in tensile energy absorption by 43% (compared to the test results obtained from the reference sheet material). The results are as shown in Fig.4b.
Moreover, it is found that using the commercial cationically modified starch and the commercial amphoterically modified starch as additives in the sheet material resulted in a decrease in tensile energy absorption by 6% (compared to the test results obtained from the reference sheet material), and that polyacrylamide cannot be used in the amount of 2% by weight because such amount of polyacrylamide causes the pulp to aggregate making it unable to be formed as sheet paper.
3. Comparison of short span compression resistance index
The test results show that sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention yielded a significant increase in short span compression resistance index compared to the reference sheet material as follows:
• the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in short span compression resistance index by 13% and 14%, respectively;
- the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in short span compression resistance index by 10% and 18%, respectively; and
-the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1 % and 2% by weight yielded an increase in short span compression resistance index by 13% and 22%, respectively.
While the sheet material comprising native hemicellulosic beta-glucan ( natural hemicellulosic beta-glucan) in an amount of 1% and 2% by weight yielded an increase in short span compression resistance index by 4% and 11%, respectively. The results are as shown in Fig. 5a. Comparing the test results obtained from the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% by weight and the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% by weight to the sheet material comprising other additives, it is found that using said two chemically modified hemicellulosic beta-glucans as additives, the resulting sheet material had a significantly greater short span compression resistance index than when using other additives. To be precise, the sheet material comprising amphoterically modified hemicellulosic beta-glucan had an increase in short span compression resistance index by 13% and the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan had an increase in short span compression resistance index by 10% (compared to the test results obtained from the reference sheet material) The results are as shown in Fig. 5b.
Moreover, it is found that using the commercial cationically modified starch and the commercial amphoterically modified starch as additives in the sheet material resulted in a decrease in short span compression resistance index by 1-2% (compared to the test results obtained from the reference sheet material), and that polyacrylamide cannot be used in the amount of 2% by weight because such amount of polyacrylamide causes the pulp to aggregate making it unable to be formed as sheet paper.
4. Comparison of ring crush resistance
The test results show that sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention yielded a significant increase in ring crush resistance of the sheet material compared to the reference sheet material as follows:
- the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of the sheet material by 14% and 21 %, respectively;
- the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of the sheet material by 13% and 20%, respectively; and -the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1 % and 2% by weight yielded an increase in ring crush resistance of the sheet material by 16% and 23%, respectively.
While the sheet material comprising native hemicellulosic beta-glucan ( natural hemicellulosic beta-glucan) in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of the sheet material by 17% and 46%, respectively. The results are as shown in Fig.6a.
Comparing the test results obtained from the sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention to the sheet material containing other additives, it is found that using chemically modified hemicellulosic beta-glucan according to the present invention as additive resulted in a significantly increased ring crush resistance. To be precise, the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in ring crush resistance by 13% and 20%, respectively and the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in ring crush resistance by 16% and 23%, respectively (compared to the test results obtained from the reference sheet material) The results are as shown in Fig.6b.
Moreover, it is found that the sheet material comprising commercial cationically modified starch in an amount of 1% and 2% by weight resulted in a decrease in ring crush resistance by 6% and an increase by 2%, respectively and that the sheet material comprising commercial amphoterically modified starch in an amount of 1% and 2% by weight resulted in a decrease in ring crush resistance by 8% and an increase by 8%, respectively (compared to the test results obtained from the reference sheet material).
5. Comparison of ring crush testing of corrugating medium
The test results show that sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention yielded a significant increase in ring crush resistance of corrugating medium of the sheet material compared to the reference sheet material as follows: - the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of corrugating medium of the sheet material by 25% and 30%, respectively;
- the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of corrugating medium of the sheet material by 28% and 38%, respectively, and
-the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in ring crush resistance of corrugating medium of the sheet material by 27% and 39%, respectively.
While the sheet material comprising native hemicellulosic beta-glucan (natural hemicellulosic beta-glucan) in an amount of 1 % and 2% by weight yielded an increase in the ring crush resistance of corrugating medium of the sheet material by 20% and 27%, respectively. The results are as shown in Fig.7a.
Comparing the test results obtained from the sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention to the sheet material containing other additives, it is found that using chemically modified hemicellulosic beta-glucan according to the present invention as additives resulted in a significant increase in ring crush resistance of corrugating medium compared to the commercial modified starch and polyacrylamide as additive. To be precise, the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in ring crush resistance of corrugating medium by 28% and 38%, respectively and that the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase ring crush resistance of corrugating medium by 27% and 39%, respectively (compared to the test results obtained from the reference sheet material). The results are as shown in Fig. 7b.
Moreover, it is found that the sheet material comprising commercial cationic starch in an amount of 1% and 2% by weight resulted in a decrease in ring crush resistance by 2% and an increase by 9%, respectively and that the sheet material comprising commercial amphoterically modified starch in an amount of 1% and 2% by weight resulted in an increase in ring crush resistance by only 4% and 16%, respectively (compared to the test results obtained from the reference sheet material).
6. Comparison of stretching of the sheet material
The test results show that sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention yielded a significant increase in stretching of the sheet material compared to the reference sheet material as follows:
- the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in stretching of the sheet material by 16% and 25%, respectively;
- the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in stretching of the sheet material by 17% and 61 %, respectively; and
- the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in stretching of the sheet material by 18% and 26%, respectively.
While the sheet material comprising native hemicellulosic beta-glucan ( natural hemicellulosic beta-glucan) in an amount of 1% and 2% by weight yielded an increase in stretching of the sheet material by 8% and 16%, respectively. The results are as shown in Fig. 8a.
Comparing the test results obtained from the sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention to the sheet material containing other additives, it is found that using chemically modified hemicellulosic beta-glucan according to the present invention as additive resulted in a significantly greater increase in stretching than sheet material containing commercial modified starch and polyacrylamide as additives. To be precise, the sheet material comprising a mixture of cationically modified hemicellulosic beta-glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in stretching by 17% and 61%, respectively and that the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight had an increase in stretching by 18% and 26%, respectively (compared to the test results obtained from the reference sheet material). The results are as shown in Fig.8b. Moreover, it is found that the sheet material comprising commercial cationically modified starch in an amount of 1% and 2% by weight resulted in an increase in stretching by only 6% and 17%, respectively (compared to the test results obtained from the reference sheet material) and that the sheet material comprising commercial amphoterically modified starch was unable to increase the stretching of the sheet material while polyacrylamide cannot be used in an amount of 2% by weight because it causes the pulp to aggregate making it unable to be formed as sheet paper.
7. Comparison of plybond strength of the sheet material
The test results show that sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention yielded a significant increase in plybond strength of the sheet material compared to the reference sheet material as follows:
- the sheet material comprising cationically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in plybond strength of the sheet material by 18% and 29%, respectively.
- the sheet material comprising a mixture of cationically modified hemicellulosic beta- glucan and anionically modified hemicellulosic beta-glucan in an amount of 1% and 2% by weight yielded an increase in plybond strength of the sheet material by 13% and 32%, respectively; and
- the sheet material comprising amphoterically modified hemicellulosic beta-glucan in an amount of 1 % and 2% by weight yielded an increase in plybond strength of the sheet material by 16% and 25%, respectively.
While the sheet material comprising native hemicellulosic beta-glucan (natural hemicellulosic beta-glucan) in an amount of 1% and 2% by weight yielded an increase in plybond strength of the sheet material by 19% and 25%, respectively. The results are as shown in Fig. 9.
8. Comparison of drainage time and freeness during the process for producing the sheet material
The test results show that for the sheet material comprising chemically modified hemicellulosic beta-glucan according to the present invention, the average process draining time was approximately 7 seconds which is not different from the reference sheet material. Considering the test results further, it was found that using natural hemicellulosic beta-glucan or chemically modified hemicellulosic beta-glucan according to the present invention as additive resulted in a decrease in freeness from 250 ml to 100 - 180 ml but the draining time was not affected compared to the using starch and polyacrylamide as additives. The results are as shown in Fig. 10.
BEST MODE OF THE INVENTION
Best mode of the invention is as disclosed in the detailed description.

Claims

A high-strength sheet material comprising:
(a) cellulose or cellulosic material; and
(b) an additive comprising chemically modified hemicellulosic beta-glucan selected from cationically modified hemicellulosic beta-glucan, anionically modified hemicellulosic beta-glucan, amphoterically modified hemicellulosic beta-glucan or a mixture of at least two of said chemically modified hemicellulosic beta-glucans.
The high-strength sheet material according to claim 1 wherein the additive is present in a range ofO.1-4.0% by weight, preferably 1-2% by weight of the dry pulp.
The high-strength sheet material according to claim 1 wherein cationically modified hemicellulosic beta-glucan is a hemicellulosic beta-glucan chemically modified with functional groups selected from amino group, imino group, ammonium group, sulfonate group, phosphonate group or at least two of said functional groups.
The high-strength sheet material according to claim 3 wherein cationically modified hemicellulosic beta-glucan preferably is hemicellulosic beta-glucan chemically modified with ammonium group.
The high-strength sheet material according to claim 4 wherein the cationically modified hemicellulosic beta-glucan chemically modified with ammonium group has a nitrogen content in a range of 0.05-0.50% by weight.
The high-strength sheet material according to claim 5 wherein the cationically modified hemicellulosic beta-glucan chemically modified with ammonium group has a preferred nitrogen content in a range of 0.10-0.30% by weight.
The high-strength sheet material according to claim 1 wherein anionically modified hemicellulosic beta-glucan is a hemicellulosic beta-glucan chemically modified with functional groups selected from carboxylate group, sulphate group, phosphate group or at least two of said functional groups.
The high-strength sheet material according to claim 7 wherein anionically modified hemicellulosic beta-glucan preferably is hemicellulosic beta-glucan chemically modified with carboxylate group.
9. The high-strength sheet material according to claim 8 wherein hemicellulosic beta- glucan chemically modified with carboxylate group has a carboxyl content in a range of 1.0-10.0% by weight.
10. The high-strength sheet material according to claim 9 wherein hemicellulosic beta- glucan chemically modified with carboxylate group has a preferred carboxyl content in a range of 2.0-5.0% by weight.
11. The high-strength sheet material according to claim 1 wherein amphoterically modified hemicellulosic beta-glucan is a hemicellulosic beta-glucan chemically modified with two functional groups, one of which is from the group consisting of amino group, imino group or ammonium group, and the other is from the group consisting of sulfonate group, phosphonate group, carboxylate group, sulphate group or phosphate group.
12. The high-strength sheet material according to claim 11 wherein the amphoterically modified hemicellulosic beta-glucan preferably is a hemicellulosic beta-glucan chemically modified with ammonium group and carboxylate group.
13. The high-strength sheet material according to claim 12 wherein the hemicellulosic beta- glucan chemically modified with ammonium group and carboxylate group has a total particle charge demand in a range of 20-2,000 μeq/g.
14. The high-strength sheet material according to one of the preceding claims wherein the chemically modified hemicellulosic beta-glucan is obtained from a reaction selected from condensation, esterification, etherification or a combination of esterification and etherification.
15. The high-strength sheet material according to claim 14 wherein the chemically modified hemicellulosic beta-glucan is preferably obtained from etherification.
16. The high-strength sheet material according to one of the preceding claims wherein hemicellulosic beta-glucan is obtained from raw materials selected from clubmosses, ferns, gymnosperm plants, angiosperm plants or a mixture of two of said raw materials.
17. The high-strength sheet material according to one of the preceding claims further comprises a crosslinking agent forming one or more network structures selected from a network of cellulose, a network of chemically modified hemicellulosic beta-glucan or a network of cellulose and chemically modified hemicellulosic beta-glucan.
18. The high-strength sheet material according to claim 17 wherein the crosslinking agent is an inorganic compound selected from metal carbonate salt, metal borate salt, metal sulfate salt, metal phosphate salt or a mixture of at least two of said metal salts.
19. The high-strength sheet material according to claim 18 wherein the crosslinking agent preferably is metal borate salt, more preferably sodium borate.
20. The high-strength sheet material according to any one of the preceding claims 17-19 wherein the crosslinking agent is present in a range of 0.025- 1.0% by weight, preferably
0.25-0.5% by weight.
21. The high-strength sheet material according to claim 1 wherein cellulose is selected from unbleached chemical pulp, unbleached semi-chemical pulp, bleached chemical pulp, waste paper pulp, recycled pulp or a mixture of at least two of said pulps.
22. The high-strength sheet material according to one of the preceding claims is printing and writing paper, food packaging paper or industrial packaging paper.
23. The high-strength sheet material according to one of the preceding claims obtained from a method for producing sheet material comprising the steps selected from applying a wet end additive; applying an additive for sizing; applying an additive for spraying or a combination of at least two of said steps.
24. The high-strength sheet material according to claim 23 wherein said method for producing sheet material preferably comprises the step of applying a wet end additive.
25. The high-strength sheet material according to claim 23 or 24 wherein the step of applying an additive in said method for producing sheet material comprises adding an additive comprising chemically modified hemicellulosic beta-glucan to react with and to bond to the cellulose fiber surface.
26. The high-strength sheet material according to claim 23-25 wherein said method for producing sheet material further comprises adding a crosslinking agent to form a network structure.
PCT/TH2017/000052 2017-06-30 2017-06-30 High-strength sheet material Ceased WO2019004950A1 (en)

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