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
  • D21H21/16—Sizing or water-repelling agents
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/001—Modification of pulp properties
  • D21C9/007—Modification of pulp properties by mechanical or physical means
• • 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
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
  • D21H11/18—Highly hydrated, swollen or fibrillatable fibres
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/10—Coatings without pigments
  • D21H19/14—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12
  • D21H19/20—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/10—Coatings without pigments
  • D21H19/14—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12
  • D21H19/20—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H19/22—Polyalkenes, e.g. polystyrene
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/38—Coatings with pigments characterised by the pigments
  • D21H19/40—Coatings with pigments characterised by the pigments siliceous, e.g. clays
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/80—Paper comprising more than one coating
  • D21H19/82—Paper comprising more than one coating superposed
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/80—Paper comprising more than one coating
  • D21H19/84—Paper comprising more than one coating on both sides of the substrate
• • 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
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/10—Packing paper

Definitions

• the present invention relates to a process for the manufacture of a wax-free twist wrapper, which may be further printable.
• Sweet treats such as candies, candied fruits, caramels, toffees, chocolates and other sweets are often provided in single portions for individual consumption and packaged in a wrapper.
• wrapper means a paper which is suitable to be used for wrapping.
• wrappers have been based on paper that is imbibed in, or impregnated with, wax or a wax-like substance.
• the resulting waxy surface of the wrapper avoids strong adhesion of the potentially sticky candy to the wrapper and on the other hand forms a barrier layer against the sometimes greasy or oily sweets, such as chocolate-coated confections, packed therein.
• the waxy surface also makes the wrapper nearly impossible to print, which is why a wrapper must be printed prior to it being waxed.
• wrappers are first provided as printable precursor wrappers, then printed on and finally waxed. This adds cost as these two separate converting steps are separated and generally not performed simultaneously.
• the wrapper according to the invention can advantageously replace wax solutions and plastic solutions.
• the sweets are first enveloped a larger sheet of wrapper and the wrapper is the twisted at one or both ends to close the wrapper.
• the forces that are applied via a packaging apparatus to the ends of the wrapper are considerable, and accordingly a certain fraction of packages will have defects, which may range from a tear in the wrapper or a cracking of the print on the wrapper in the region of, or the region surrounding, the twisted portion of the wrapper.
• plastic films are printable, exhibit barrier properties and have good mechanical properties that avoid tearing during packaging, they are considered undesirable as twist wrappers because they cannot be recycled easily and because they are generally sourced from petrochemical products.
• paper-based twist wrappers that are waxed are not easily printed and cannot be recycled because of the high wax content they exhibit.
• twist wrapper that is easily printable, which exhibits good mechanical properties, especially when twisted, and which exhibits good barrier properties while being easily recyclable. Furthermore, the twist wrapper should ideally be able to be used at high throughput, i.e. at speeds in excess of 1 500 candy pieces per minute, or even in excess of 2 000 candy pieces per minute.
• the present invention provides a twist wrapper that is easily printable, which exhibits good mechanical properties, especially when twisted, and which exhibits good barrier properties while being easily recyclable, as well as a method to produce such a twist wrapper.
• the twist wrapper according to the present invention is free of wax or wax-like substances impregnation that interfere with the printing and/or recycling of the twist wrapper, and provides printability, barrier properties, and recyclability via an alternative structure. Furthermore, the wrapper can only be printed (and requires no waxing) before being used as twist wrapper.
• the furnish comprising a mixture of softwood and hardwood has a technical effect of improving the mechanical resistance of the wrapper.
• the furnish comprising a mixture of soft- and hardwood contributes also to the final TAPPI value; the effect is due to the limited penetration of the coating inside the paper.
• the paper substrate according to the invention advantageously has a weight of between 35 gsm and 50 gsm. In a preferred embodiment of the process for the manufacture of a wax-free printable twist wrapper according to the first object of the present invention, the paper substrate according to the invention advantageously has a weight of between 42 and 48 gsm.
• the paper substate i.e the still uncoated twist wrapper
• the paper substate has a weight of about from 25 gsm to 45 gsm, preferably of from 30 to 40 gsm.
• the weight, or grammage, of the paper substrate may be determined according to ISO 536, at 23 °C and 50% rel. humidity.
• the hardwood pulp may be sourced from hardwoods such as for example birch, eucalyptus or blends of both.
• the clay pigment is a kaolin.
• the step of coating the paper on the opposed side with a barrier layer is carried out in a coating device, more preferably onto a precoat layer on the opposed side of the paper substrate, which precoat layer is applied in the paper machine, in particular in the forming section.
• the precoat layer coated on the opposed side of the paper substrate comprises preferably a precoat composition, which composition may comprise copolymers of styrene, polymers, or copolymers of polyvinyl alcohol, or microfibrillated cellulose.
• a precoat composition which composition may comprise copolymers of styrene, polymers, or copolymers of polyvinyl alcohol, or microfibrillated cellulose.
• the precoat layer may essentially consist of polyvinyl alcohol or of microfibrillated cellulose in some embodiments.
• the moisture content of the printable twist wrapper precursor is increased by the addition of water to the printable twist wrapper precursor.
• Adding water to the printable twist wrapper precursor can be achieved via sprinkling or spraying a water mist onto the printable twist wrapper precursor.
• the purpose of increasing the moisture content of the printable twist wrapper precursor is primarily that of preparing the printable twist wrapper precursor for the subsequent step of densification and drying. Densification is more efficiently achieved on a damp paper and drying the paper to a moisture content of between 5% and 15% requires that the paper comprises a certain "reservoir" of humidity prior to drying.
• the moisture content of the printable twist wrapper precursor may be increased to a value of more than 5% by weight when the target moisture in the final printable twist wrapper precursor should be approx. 5% by weight.
• the moisture content of the printable twist wrapper precursor may be increased to a value of more than 10% by weight when the target moisture in the final printable twist wrapper precursor should be approx. 10% by weight, and so on. Therefore, in some embodiments of the first object of the present invention, the moisture content of the printable twist wrapper precursor may be increased to a value of more than 5, 8, 11, 14, 15 or more % by weight. It was found that increasing moisture content can have an advantageous effect on resistance to twisting; twist wrappers having high moisture will be more flexible; by increasing the moisture one avoids a dry wrapper which will be more brittle.
• the increase of the moisture content of the printable twist wrapper precursor to a value of more than 5% by weight based on the weight of the printable twist wrapper precursor is due to the step of coating the paper on opposed side with a barrier layer, which requires drying the barrier layer composition, and thus necessarily the underlying paper substrate, as well as the barrier layer, to a moisture of less than 5%.
• the step of densifying the printable twist wrapper precursor and decreasing the moisture content of the printable twist wrapper precursor may be carried out by either first drying and then densifying or densifying and then drying, both may also be carried out simultaneously.
• a moisture content of from 5% to 15% provides the printable twist wrapper with a suitable suppleness and flexibility that is needed when wrapping a confection at high speeds on a wrapper machine.
• the occurrence of blocking during the unwinding of reels of twist wrapper can be avoided.
• Increasing moisture content above 15% is possible, but not preferable, because it may result in blocking, as well as problems with unwinding the twist wrapper - paper may stick and then also cause runnability issues with printing at the final user side.
• the step of densifying the printable twist wrapper precursor and decreasing the moisture content of the printable twist wrapper precursor is simultaneously achieved by supercalendering the printable twist wrapper precursor.
• Supercalendering is achieved by passing the printable twist wrapper precursor through the nips of a supercalender.
• Supercalendering is further useful to increase the gloss of the printable twist wrapper and increase the smoothness of the printable twist wrapper. Supercalendering improves stiffness, but does not contribute significantly to the barrier properties.
• Decreasing the moisture content may be carried out at any temperature, and may in some cases be supplemented by the application of an under-pressure or vacuum, but is preferably carried out at a temperature of between 75° and 130 °C, especially when carried out at atmospheric pressure.
• Densifying is carried out by subjecting the printable twist wrapper precursor to pressure across the thickness of the printable twist wrapper precursor, which linear pressure may be in the range 180 N/mm to 280 N/mm.
• the printable twist wrapper has a weight of from 30 g/m 2 to 60 g/m 2 , and preferably has a weight of from 35 g/m 2 to 50 g/m 2 .
• the print receiving layer has a weight of from 3 g/m 2 to 11 g/m 2 , preferably of from 4 g/m 2 to 7 g/m 2 and more preferably of from 2 g/m 2 to 6 g/m 2 and/or wherein the barrier layer has a weight of from 0.5 g/m 2 to 8 g/m 2 , preferably of from 1 g/m 2 to 6 g/m 2 , more preferably of from 2 g/m 2 to 5 g/m 2 .
• the mixture of at least one hardwood pulp and at least one softwood pulp comprises at least two and preferably two softwood pulps.
• the barrier polymer comprised in the barrier layer, or in the barrier layer composition are chosen among polymers or copolymers of styrene or polymers or copolymers of polyvinyl alcohol, preferably among polymers or copolymers of vinyl alcohol.
• the barrier layer comprises, or essentially consists, of a barrier polymer that is a polymer or copolymer of vinyl alcohol such as polyvinylalcohol (PVOH).
• the wax-free printable twist wrapper after the step of densifying the printable twist wrapper precursor and decreasing the moisture content of the printable twist wrapper precursor, the wax-free printable twist wrapper has a thickness of from 3 ⁇ m to 8 ⁇ m.
• the wax-free printable twist wrapper according to the second object of the present invention, which may be obtained via the above process according to the first object of the present invention, having a grease resistance value of 4, or of from 4 to 12, when measured according to TAPPI Test method T559, comprises, or consists of,
• the hardwood pulp may be sourced from hardwoods such as for example birch and eucalyptus, or mixtures of both.
• the softwood pulp may be sourced from softwoods such as for example spruce and pine, or mixtures of both.
• the hardwood and softwood pulps are both preferably chemical pulps, such as Kraft pulp, sulfite pulp or dissolving pulp.
• the hardwood and softwood pulps are bleached hardwood and softwood pulps. Consequently, in a much-preferred embodiment of the wax-free printable twist wrapper according to the second object of the present invention, both hardwood and softwood pulps are bleached chemical pulps, such as for example Bleached Softwood Kraft (BSK) and Bleached Hardwood Kraft (BHK).
• BSK Bleached Softwood Kraft
• BHK Bleached Hardwood Kraft
• the mixture of at least one hardwood pulp and at least one softwood pulp at least 40 % by weight are formed by the at least one hard wood pulp, and preferably at least 50 % by weight are formed by the at least one hard wood pulp.
• the mixture of at least one hardwood pulp and at least one softwood pulp provides for a paper substrate and/or wax-free printable twist wrapper that has excellent mechanical properties.
• the print receiving layer comprises at least one binder and at least one clay pigment, and is generally coated onto the paper substrate as a print receiving layer composition, where the print receiving layer composition is a liquid or slurry. Coating the paper on one side with a print receiving layer may be carried in the paper machine or may be carried out outside the paper machine in a separate coating device.
• the coating the paper on one side with a print receiving layer may be carried out in either the paper machine, in particular in the forming section of the paper machine, or may be carried out outside the paper machine in a separate coating device, it has been found that coating the paper on one side with a print receiving layer is advantageous, in terms of process flexibility, because the application the print receiving layer in the paper machine frees up coating capability in an ensuing coating step outside the paper machine in a coating device.
• the step of coating the paper on one side with a print receiving layer is carried out in the paper machine, in particular in the forming section.
• the print receiving layer composition is normally applied as liquid or slurry and will thus comprise the polymer binder in a liquified form, most commonly in the form of an emulsion or a dispersion. Likewise, the clay pigment will be suspended in the print receiving layer composition. It is understood that the print receiving layer composition may further comprise other components in addition to the binder and the pigment, such as for example biocides, dispersants, rheology modifiers and such.
• the print receiving layer on one side of the paper substrate comprises at least one binder and at least one clay pigment.
• the binder may be, for example a polymer binder such as a copolymer of styrene. Known copolymer of styrene are, for example, styrene butadiene copolymer or styrene acrylic copolymer.
• the clay pigment may be, for example, a kaolin.
• the wax-free printable twist wrapper according to the second object of the present invention can be provided as ready-to-use wrapper that can easily be printed on demand, because it has already the barrier properties and the printability that are required.
• the wax-free printable twist wrappers described above according to the invention were subjected to multiple tests to determine the tensile strength, the elongation at break as well as the tearing strength in both machine (MD) and cross direction (CD), and the average values obtained from the wrappers are compared to a commercially available, conventional wax-impregnated and printed twist wrapper in the below table.
• a wax-free printable twist wrappers according to the invention emulate the mechanical properties of a conventional waxed and printed twist wrapper. The results are summarized in Table 1.
• the wax-free printable twist wrappers according to the present invention could be used in a commercial setting for wrapping hard candy on a Theeberg EK4 machine at a speed of 2000 pcs/min or more, as a "plug-in" substitute for commercially available printed & waxed wrapper papers.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Dispersion Chemistry (AREA)
• Paper (AREA)

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Citations (7)

• 2024
  • 2024-03-28 ES ES24167635T patent/ES3062368T3/es active Active
  • 2024-03-28 EP EP24167635.2A patent/EP4624657B1/de active Active
• 2025
  • 2025-03-25 WO PCT/EP2025/058040 patent/WO2025202157A1/en active Pending

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