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EP4368773A1 - Papier de base de doublure détachable à base de fibres recyclées pour application de doublure détachable - Google Patents

Papier de base de doublure détachable à base de fibres recyclées pour application de doublure détachable Download PDF

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Publication number
EP4368773A1
EP4368773A1 EP22207031.0A EP22207031A EP4368773A1 EP 4368773 A1 EP4368773 A1 EP 4368773A1 EP 22207031 A EP22207031 A EP 22207031A EP 4368773 A1 EP4368773 A1 EP 4368773A1
Authority
EP
European Patent Office
Prior art keywords
release liner
base paper
fibers
liner base
recycled
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.)
Withdrawn
Application number
EP22207031.0A
Other languages
German (de)
English (en)
Inventor
Marco Aversa
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.)
Ahlstrom Corp
Original Assignee
Ahlstrom Corp
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 Ahlstrom Corp filed Critical Ahlstrom Corp
Priority to EP22207031.0A priority Critical patent/EP4368773A1/fr
Priority to CN202380074903.1A priority patent/CN120187918A/zh
Priority to EP23755384.7A priority patent/EP4616028A1/fr
Priority to PCT/EP2023/072327 priority patent/WO2024099607A1/fr
Priority to KR1020257014367A priority patent/KR20250103633A/ko
Publication of EP4368773A1 publication Critical patent/EP4368773A1/fr
Withdrawn legal-status Critical Current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
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/001—Release paper
    • 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
    • D21H11/14—Secondary 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
    • D21H19/16—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising curable or polymerisable compounds
    • 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
    • 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
    • D21H27/06—Vegetable or imitation parchment; Glassine paper

Definitions

  • the present invention relates to a high-quality release liner base paper comprising at least 5 wt% recycled fibers coming from recycled cardboard-based fibers, printed material-based fibers, or both of diverse sources and having a density of at least 1.00 g/cm 3 . Moreover, it relates to a method of producing the release liner base paper described herein.
  • Further aspects of the present invention relate to the use of the release liner base paper in a method of producing a release liner, to the release liner comprising the release liner base paper and to a laminate comprising the release liner.
  • Release liners are efficient carriers for self-adhesive labels and adhesive materials. They are formed by applying a release coating composition on a base layer and curing the coating composition to provide a release coating layer, generally a silicone layer. Self-adhesive labels and self-adhesive materials can be found everywhere in everyday products as well as in complex applications and durable equipment.
  • Base layers that are to be siliconized must possess certain properties to guarantee two primary functions of the release liner: protection of the self-adhesive products before use and perfect adhesive transfer upon removal. Key features required in the manufacture of such base layers include diverse mechanical properties and perfect silicone anchorage.
  • the base layer should also have a low air permeability to limit penetration of the silicone inside the base layer as much as possible in order to achieve sufficient release properties and to reduce the amount of silicone.
  • the base layer should also have a high density to have mechanical properties enabling a further die-cutting step of labels disposed on the siliconized base layer. Furthermore, the chemical structure of the base layer must not prevent the silicone system from crosslinking.
  • natural fiber-based release liners help to reduce product waste as they comprise a base layer paper made from cellulose fibers and thus suitable for recycling.
  • cellulose fibers are derived from wood which is a fully renewable source. Nevertheless, the globally pursued social goal of sustainability also extends to the release liner market. In view of their countless applications, there is an increasing demand for even more sustainable release liners to help preserve the environment, save resources, and decrease the carbon footprint of the release liners.
  • Such poisoning additives are substances known as inhibiting or poisoning the crosslinking reaction of silicone release coatings (see Form No. 30-1053-01, on consumer.dow.com).
  • examples of such inhibitors or poisons are optical-brightening agents, colorants, deink-agents and other compounds containing one or more selected from nitrogen, sulfur and phosphorus groups.
  • the present invention is based on the finding that the above problem can be solved by using at least 5 wt% recycled fibers coming from recycled cardboard-based fibers, printed material-based fibers, or both to prepare a release liner base paper with a density of at least 1.00g/cm 3 . That is, the present invention provides a more sustainable release liner base paper comprising significant amounts of recycled fibers from a wide range of sources while maintaining the desired features.
  • the present invention provides a release liner base paper comprising at least 5 wt% recycled fibers coming from recycled cardboard-based fibers, printed material-based fibers or both and having a density of at least 1.00 g/cm 3 .
  • the invention provides a method for producing the release liner base paper.
  • the method comprises the steps of dispersing recycled fibers and optionally virgin fibers in a pulper, refining the suspension of fibers, disposing the suspension of refined fibers on a forming wire and dewatering it, applying a primer composition on at least one side of the dewatered paper web, and drying the same.
  • the invention provides the use of the release liner base paper according to the first aspect as a base layer in a method of producing a release liner.
  • the method comprises the steps of applying a release coating composition on at least one side of the release liner base paper, and curing the composition to form a release coating layer.
  • the invention provides a release liner comprising the release liner base paper according to the first aspect and a release coating layer on at least one side of the base layer.
  • the invention provides a laminate comprising the release liner according to the fourth aspect, a face stock and an adhesive layer provided between the release liner and the face stock.
  • the present invention relates to a novel release liner base paper that comprises recycled fibers and has a density of at least 1.00 g/cm 3 .
  • the recycled fibers are recycled cardboard-based fibers, printed material-based fibers, or both, and the amount of the recycled fibers in the release liner base paper is at least 5 wt%, based on the total weight of fibers in the release liner base paper.
  • recycled fibers refers to fibers coming from recovered and reprocessed waste materials for use in new products. Recycling is the key aspect for a circular economy and thus saves resources in terms of starting materials. That is, recycled fibers are derived from products that were once manufactured using virgin fibers.
  • virgin fiber refers to a fiber that has not yet been processed in the manufacturing of a product.
  • the fibers comprised in the base paper according to the present invention preferably consist of cellulosic fibers.
  • the base paper may comprise natural cellulosic fibers including pulp, man-made fibers, or a mixture thereof.
  • Man-made fibers can be synthetic fibers or modified cellulosic fibers also known as regenerated cellulose fibers.
  • Lyocell and Viscose There are two main classes of regenerated cellulose: Lyocell and Viscose, aka Rayon.
  • Cellulose fibers have a range of diameters and length that depends on the fiber type and source. In general, however, the length of recycled fibers is shorter than that of untreated virgin fibers of the same type and source.
  • the recycled fibers according to the present invention are not limited to a specific origin but based on general post-consumer waste selected from recycled cardboard-based fibers, recycled printed material-based fibers or both.
  • the recycled fibers are such as the ones comprised in groups 1, 2, 3 except grade numbers 3.18 and 3.20, 4, and 5 except grade numbers 5.05.03 and 5.06, as defined in EN 643.
  • Exemplary embodiments of printed material and cardboards comprise product packaging materials, newspapers, printed office papers, printed writing papers, printed letters and envelopes, multiply boards, boxes, kraft sacks, paper cups and tableware, books and magazines.
  • the recycled fibers according to the present invention comprise a huge variety of materials.
  • the amount of the recycled fibers of at least 5 wt% implies an amount of virgin fibers in the release liner base paper of 95 wt% or less, based on the total weight of fibers in the release liner base paper.
  • the total weight of fibers in the release liner base paper refers to the dry weight of fibers.
  • the virgin fibers commonly used to prepare release liner base papers can be chosen among bleached or unbleached softwood pulp, bleached or unbleached hardwood pulp, bleached or unbleached chemical pulp from hardwood or softwood, bleached or unbleached chemi-thermomechanical pulp from hardwood or softwood, or mixtures thereof.
  • the virgin fibers may comprise at least 10 wt%, or at least 25 wt%, or at least 45 wt%, or at least 70 wt% of bleached chemical pulp based on the total weight of the virgin fibers.
  • the bleached chemical pulp can be constituted by a blend of hardwood and softwood fibers, the hardwood fibers being present in this blend in an amount of at least 50 wt%, preferably at least 75 wt%, based on the total weight of the bleached chemical pulp, and the softwood fibers being present in an amount of at most 50 wt%, preferably at most 25 wt%, based on the total weight of the bleached chemical pulp.
  • the virgin fibers may further comprise at least 2 wt% and less than 50 wt% of bleached chemi-thermomechanical pulp, based on the total weight of the virgin fibers.
  • the bleached chemi-thermomechanical pulp can be present in the virgin fibers in an amount of 5 to 45 wt%, or of 10 to 35 wt%, based on the total weight of the virgin fibers.
  • release liner base papers comprising at least 5 wt% recycled fibers according to the invention are equivalent or better than those that do not contain recycled fibers.
  • the overall good properties are in particular unexpected considering that the recycled cardboard-based and printed material-based fibers are of quite diverse sources that go hand in hand with a wide range in impurities.
  • the heterogenous fiber mixture that is a mixture of virgin fibers and recycled fibers, seems to result in a specific structural design, wherein the recycled fibers according to the present invention interact with the commonly used virgin fibers. That way, a particularly beneficial structure of the base paper results which is capable of compensating negative effects resulting from the presence of impurities.
  • release liner base papers comprising at least 5 wt% recycled fibers according to the invention, are more closed than base papers not containing recycled fibers. That is, the base paper according to the present invention shows improved (lower) air permeability with increasing amounts of recycled fibers.
  • FIG. 1 compares the air permeability values of base papers comprising 0 wt% (not indicated), 14.3 wt% and 21.4 wt% recycled fibers. The measuring points result from measurements on Jumbo rolls of the different base papers produced in a continuous process.
  • the recycled fibers according to the present invention appear to be able to interact with the virgin fibers in a particularly beneficial tight manner.
  • the amount of recycled fibers in the release liner base paper is at least 10 wt%, preferably from 15 wt% to 80 wt%, more preferably from 20 wt% to 50 wt%, based on the total weight of fibers in the release liner base paper.
  • Air permeability, energy saving and saving resources are further improved when the amount of recycled fibers in the release liner base paper is at least within the preferred lower ranges specified above.
  • FIG. 2 compares the Rizinus Cobb values of base papers comprising 0 wt% (not indicated), 14.3 wt% and 21.4 wt% recycled fibers. The measuring points result from measurements on Jumbo rolls of the different base papers produced in a continuous process.
  • the release liner base paper has a density of 1.05 g/cm 3 to 1.26 g/cm 3 , preferably of 1.09 g/cm 3 to 1.24 g/cm 3 , and more preferably of 1.12 g/cm 3 to 1.22 g/cm 3 .
  • the density may be measured by methods well known in the field of papers. For instance, the density may be calculated by dividing the basis weight of the release liner base paper (measured according to ISO 536 standard) with the thickness of this release liner base paper (measured according to ISO 534 standard).
  • the density of the release liner base paper represents a technical feature characteristic for the high-quality of the base paper required to provide release liners with desired properties. That is, a high density of at least 1.00 g/cm 3 ensures that the release liner base paper has mechanical properties enabling a further die-cutting step of labels disposed on a release liner without cutting this release liner.
  • quality of the release liner base paper and suitability for coating with a silicone release coating composition may further be determined by the following technical features.
  • the primary functions of the release liner previously discussed may be further improved if one or more of the technical features selected from the group consisting of air permeability, transparency, Bekk smoothness, Rizinus Cobb, tensile strength and tear resistance can be further improved.
  • the silicone release coating composition needs to remain at the surface of the base paper to limit the silicone consumptions while producing the release liner. Accordingly, the release liner base paper should absorb as little silicone as possible.
  • the base paper has an air permeability from 100 pm/Pa•s to 70000 pm/Pa•s.
  • air permeability is the rate of airflow passing perpendicularly through a known area under a prescribed air pressure differential between the two surfaces of a material.
  • the base paper has an air permeability in the range from 500 pm/Pa•s to 50000 pm/Pa•s, measured according to SCAN P26 standard.
  • silicone adhesion may be further improved.
  • FIG. 1 it has been found that air permeability decreases with an increasing amount of recycled fibers according to the present invention.
  • the release liner base paper has a transparency of 4% to 65%, preferably of 25% to 60%, measured according to DIN 53147 standard, and a basis weight of 30 g/m 2 to 140 g/m 2 , preferably of 45 g/m 2 to 90 g/m 2 , measured according to ISO 536. Transparency may be particularly relevant for specific classes of release liner base papers, such as the high-end product glassine described in further detail below. It is achieved by super calendering the base paper as described below in further detail until the desired degree of transparency is reached.
  • the basis weight of the release liner base paper includes the basis weight of an optionally primer formed on at least one side of the base paper according to the preferred embodiment defined in further detail below.
  • the base paper has a Bekk smoothness on the back side of 15 s to 1500 s, preferably of 25 s to 1200 s and on the top side of 400 s to 4000 s, preferably of 500 s to 3500 s, measured according to TAPPI T479 standard.
  • Bekk smoothness is below the recited ranges, formation of the release coating layer may be deteriorated.
  • the base paper has a Rizinus Cobb value of 0.2 g/m 2 to 4 g/m 2 , preferably of 0.3 g/m 2 and 3 g/m 2 , more preferably of 0.6 g/m 2 to 1.4 g/m 2 .
  • the Rizinus Cobb refers to the oil permeability and is measured on the top side according to ISO 535 standard.
  • a release liner base papers comprising at least 20 wt% recycled fibers according to the invention may be even more closed, resulting in an improved (lowered) Rizinus Cobb.
  • Rizinus Cobb values measure the ability for the silicone to penetrate into the release liner base paper. Release liner base papers with lower Rizinus Cobb value allow less penetration of silicone into the paper, therefore reducing the silicone consumption in the production of release liner.
  • the release liner base paper has a tensile strength in machine direction of 2.0 kN/m to 18.0 kN/m, preferably of 4.0 kN/m to 15.0 kN/m and in cross direction of 1.0 kN/m to 15 kN/m, preferably of 2.0 kN/m to 12.0 kN/m, measured according to ISO 1924 standard.
  • the tensile strength refers to a maximum tensile force per unit width that paper and board will withstand before breaking under the conditions defined in the ISO 1924 standard.
  • the base paper has a tear resistance in machine direction of 100 mN to 1500 mN, preferably of 150 mN to 1300 mN and in cross-machine direction of 100 mN to 1500 mN, preferably of 150 mN to 1300 mN, measured according to ISO 1974 standard.
  • the tear resistance refers to the maximum force required to tear a specimen in a particular direction.
  • machine direction refers the direction that the paper moves through the paper machine and the term "cross-machine direction”, also known as “transverse direction”, is the direction perpendicular to the machine direction.
  • the release liner base release liner base paper of the present invention can be preferably selected from the group of release liner known in the field of paper release liners consisting of glassine papers, clay coated kraft (CCK) papers, super calendered kraft (SCK).
  • the release liner base paper of the present invention is a glassine paper.
  • Glassine papers are typically made of bleached chemical pulp and widely used in release liners for self-adhesive materials.
  • Glassine preferably has a transparency of 43% for a basis weight of 90 g/m 2 up to 55% for a basis weight of 45 g/m 2 .
  • the base paper has a Gurley value of 100 s to 2000 s, when measured in a remoistened state immediately before the step of super calendering according to ISO 3687 standard.
  • the release liner base paper is a clay coated kraft (CCK) paper.
  • CCK paper typically comprises a paper base substrate with a clay coated front side for high quality printing that is used where a good dimensional stability is required.
  • the release liner base paper comprises a primer applied on at least one side.
  • the primer is compatible with a silicone release coating composition.
  • the primer may comprise at least one water soluble binder selected from the group consisting of polyvinyl alcohol, polyvinyl alcohol modified with alkene groups, silanol groups or silane hydride groups, starch, alginate, or carboxymethyl cellulose.
  • the primer comprises modified polyvinyl alcohol as disclosed in EP 2 539 505 .
  • the basis weight of the primer formed by coating on at least one side of the glassine paper is between 0.1 g/m 2 to 10 g/m 2 , more preferably between 1 g/m 2 to 3 g/m 2 .
  • the primer is a coating layer comprising at least one pigment and a latex as binder.
  • the at least one pigment may be chosen among clay, carbonate or talc.
  • the pigment is calcium carbonate
  • the binder is an emulsion comprising styrene butadiene and styrene acrylate.
  • the binder may constitute approximately 25 wt% in dry weight of the primer and the carbonate may constitute approximately 75 wt% in dry weight of the primer.
  • the basis weight of the primer formed by coating on at least one side of the CCK paper is between 15 g/m 2 to 30 g/m 2 , more preferably 20 g/m 2 .
  • the present invention relates to a method of producing the release liner base paper according to the first aspect.
  • the method comprises the steps of dispersing recycled fibers and optionally virgin fibers in a pulper (step a), refining the suspension of fibers (step b), disposing the suspension of refined fibers on a forming wire (step c) and dewatering it (step d), applying a primer composition on at least one side of the dewatered paper web (step e), and drying the same (step f).
  • the recycled fibers are recycled cardboard-based fibers, printed material-based fibers, or both, and the amount of the recycled fibers in the release liner base paper is at least 5 wt%, based on the total weight of fibers in the release liner base paper.
  • the method of producing the release liner base paper according to the second aspect of the present invention may be performed by using equipment for paper production known in the art.
  • the method may be performed in a continuous process or may be interrupted when changing the equipment.
  • the recycled cardboard-based fibers, printed material-based fibers, or both of the second aspect of the present invention are as defined above with regard to the first aspect.
  • the amount of the recycled fibers of at least 5 wt% implies an amount of virgin fibers in the release liner base paper of 95 wt% or less, based on the total weight of fibers in the release liner base paper, that is dispersed in step a) with the recycled fibers in a pulper.
  • the step b) of refining fibers generally requires high energy. It is applied to increase the specific surface of the fibers and thus improve smoothness and density of the base paper.
  • the pulp is typically refined to achieve a fiber fineness that results in a dense, almost non-porous paper surface. Such a surface is highly resistant to air and liquids, such as oil and water.
  • the refining energy in step b) can be reduced without any deterioration of the desired base paper features.
  • FIG. 3 and FIG. 4 the air permeability and Rizinus Cobb values of another base paper comprising 14.3 wt% recycled fibers according to the present invention are compared with the properties of a comparative standard base paper (comprising 0 wt% recycled fibers, not indicated). Said base paper according to the present invention has been obtained with a reduction in refining energy of 11% compared to the standard base paper. Accordingly, the method of producing the release liner base paper according to the second aspect of the present invention reduces the refining energy required for the production of release liner base papers while maintaining the high-quality requirements.
  • the primer composition is disposed on at least one side of the release liner base paper by any suitable method, and preferably by rod coating or blade coating.
  • the primer composition may comprise at least one water soluble binder selected from the group consisting of polyvinyl alcohol, polyvinyl alcohol modified with alkene groups, silanol groups or silane hydride groups, starch, alginate, or carboxymethyl cellulose in order to achieve compatibility with a silicone release coating composition applied in a later step as described below.
  • a particular preferred primer composition may comprise modified polyvinyl alcohol as described in EP 2 539 505 .
  • the basis weight of the primer formed by coating on at least one side of the glassine paper is between 0.1 g/m 2 to 10 g/m 2 , more preferably between 1 g/m 2 to 3 g/m 2 .
  • the primer composition may comprise at least one pigment and a latex as binder.
  • the at least one pigment may be chosen among clay, carbonate, or talc.
  • the pigment is calcium carbonate
  • the binder is an emulsion comprising styrene butadiene and styrene acrylate.
  • the binder may constitute approximately 25 wt% and the carbonate may constitute approximately 75 wt%, each in dry weight of the primer composition.
  • the basis weight of the primer formed by coating on at least one side of the CCK paper is between 15 g/m 2 to 30 g/m 2 , more preferably 20 g/m 2 .
  • the method further comprises a step of calendering the dried primer-coated paper web.
  • the release liner base paper of the present invention is a glassine paper according to the first aspect
  • the primer-coated paper web is subjected to a series of moisturising and multi-nip calender or super calendering steps, to obtain a very dense paper having a smooth surface, high impact strength, high tear resistance and transparency.
  • calendering is performed with only one nip.
  • the amount of recycled fibers in the release liner base paper is at least 10 wt%, preferably from 15 wt% to 80 wt%, more preferably from 20 wt% to 50 wt%, based on the total weight of fibers in the release liner base paper.
  • the basis weight of the primer layer applied on at least one side of the paper is 0.1 g/m 2 to 30 g/m 2 , preferably 1 g/m 2 to 20 g/m 2 , measured according to ISO 536.
  • the basis weight of the primer layer refers to the primer layer being in a dried state.
  • the basis weight of the primer may be between 0.1 g/m 2 to 10 g/m 2 , more preferably between 1 g/m 2 to 3 g/m 2 .
  • the basis weight of the primer may be between 15 g/m 2 to 30 g/m 2 , more preferably 20 g/m 2 .
  • the recycled fibers used in step a) of the method have a dry content of more than 50%, measured according to TAPPI 210 standard. Using fibers with a dry content of more than 50%, is more ecological in terms of transportation, storage and processability due to increased raw material per volume rates.
  • the recycled fibers used in step a) of the method have a pulp freeness of 25°SR to 60°SR, preferably of 30°SR to 50°SR, measured according to a derivative of UNI 7621 standard.
  • the recycled fibers contribute to reduce the refining energy that has to be applied at the pulp mix to reach the desired air permeability level on the finished products.
  • the recycled fibers used in step a) of the method have an ash content of 0.1% to 8%, preferably of 0.5% to 7%, measured according to a derivative of TAPPI 211 standard.
  • the ash content is in the range of 0.1% to 8%, effects resulting from the previously described specific structural design are further improved, while transparency and mechanical properties of the finished products are not influenced.
  • the recycled fibers used in step a) of the method have a pH value of 5 to 12, preferably of 6 to 11, measured according to a derivative of TAPPI 209 standard.
  • a pH value of 5 to 12 guarantees a good stability of the production process and avoids negative effect on the characteristics of the finished product.
  • the recycled fibers have a dry content of more than 50%, a pulp freeness of 25°SR to 60°SR, an ash content of 0.1% to 8%, and a pH value of 5 to 12, and in a most preferred embodiment of the second aspect, the recycled fibers have a dry content of more than 50%, a pulp freeness of 30°SR to 50°SR, an ash content of 0.5% to 7%, and a pH value of 6 to 11, each measured according to the standards defined above.
  • the present invention relates to a use of the release liner base paper according to the first aspect as a base layer in a method of producing a release liner.
  • the method comprises the steps of applying a release coating composition on at least one side of the release liner base paper and curing the composition to form a release coating layer.
  • curing is synonymous to “crosslinking” and refers to the polyaddition reaction between the vinylic functional groups of the silicone resin and the hydrogen siloxane functional groups of the crosslinking agent.
  • the silicone release coating composition according to the third aspect may be applied to a side of the release liner base paper comprising a primer as defined above, which is compatible with the silicone release coating composition.
  • Silicone release coating compositions known in the field of release liners such as disclosed in EP 2 539 505 may be applied on at least one side of the release liner base paper.
  • such compositions comprise a polymer, a crosslinker and a catalyst, preferable a platinum-based catalyst.
  • crosslinking is performed by curing the composition at high temperatures until curing is complete.
  • crosslinking is performed for 10 seconds to 120 seconds, at temperatures in the range of 70 °C to 160 °C and under air flow, particularly preferably, in a ventilated drying kiln.
  • the present invention relates to a release liner comprising the release liner base paper according to the first aspect as a base layer and a release coating layer on at least one side of the base layer.
  • the release coating is silicone.
  • silicone anchoring and crosslinking of the release liner base papers comprising at least 5 wt% recycled fibers according to the present invention meet stringent performance targets for a release liner material. This is particularly surprising considering that the recycled cardboard-based and printed material-based fibers in the base papers are of quite diverse sources that go hand in hand with a wide range in impurities, including silicon-curing poisoning additives as described above. Without wishing to be bound by theory, it appears that the previously described specific structural design of the base paper according to the present invention compensates any negative impact usually accompanying high ash contents.
  • the rate of crosslinking and the anchorage of the silicone layer are examined by the subsequently described poly and "rub off" tests.
  • the silicone crosslinking is analysed by the poly test measuring the quantity of silicone remaining on a sample of siliconized paper after it had been immersed in an organic solvent for non-crosslinked silicone (toluene or methyl isobutyl ketone).
  • Anchorage of the silicone to the paper is analysed by the rub off test. This test measures the remaining silicone layer after an abrasion test on a textile under a weight. More particularly, the rub-off test is conducted by applying a dynamic force of 225 g/cm 2 on the silicone coated paper substrate at a speed of 7 m/min for 25 cm.
  • the release liner base paper has a silicone crosslinking of at least 95%, more preferably in the range between 96% and 100%, since a rate higher than 96% is indicative of particularly satisfactory crosslinking.
  • silicone anchorage on the at least one side of the release liner base paper is of at least 60%, preferably of at least 80%, more preferably of 95% to 100%.
  • a rate above 60% confirms sufficient anchorage, a rate above 80% is generally indicative of good anchorage. Value is significant if the poly test is higher than 95 %.
  • Fields of application of the release liner according to the fourth aspect are very diverse. Without being limited hereto, they may be used in high-speed labelling applications for branding of consumer goods, but also for their pricing, identification or weighting. Further, the release liner may be used in medical applications, such as release liners protected plasters, transdermal drug delivery systems, or ostomy products, preserving hygiene, efficient treatments, and human health. Another exemplarily application may be the use in double-side adhesive tapes to assemble components.
  • the present invention relates to a laminate comprising the release liner according to the fourth aspect, a face stock and an adhesive layer provided between the release liner and the face stock.
  • the high-end product glassine sets the highest standards on its mechanical properties and usually requires a very high quality of the fibers used. The following experiments will therefore illustrate the effects of the present invention using this high-end product class.
  • virgin fibers and recycled fibers were used to prepare release liner base papers.
  • virgin fibers a commercially available standard pulp as defined above used in the manufacturing of release liners and comprising 100% virgin cellulose fibers was used.
  • recycled fibers As recycled fibers, a recycled pulp supplied by WEPA Greenfield SAS comprising 100% fibers coming from a mixture of recycled cardboard and printed materials ( cf. groups 1, 2, 3 except grade numbers 3.18 and 3.20, 4, and 5 except grade numbers 5.05.03 and 5.06, as defined in EN 643).
  • the recycled fibers had a pulp freeness of 34° SR, an ash content of 1.36 % and a pH value of 8.58, each measured according to the standards described above.
  • glassine release liner base papers were produced in a continuous process on a standard paper machine and the influence of varying amounts of recycled fibers was investigated.
  • the suspension of refined fibers was disposed on a flat forming wire and dewatered.
  • a primer composition was prepared.
  • the primer composition corresponded to a polyvinyl alcohol modified composition as disclosed in EP 2 539 505 .
  • the primer composition was applied on the top side of the dewatered paper web by metering-size-press coating at 65°C, the back side being coated with a surface treatment agent (such as for example polyvinyl alcohol, starch, CMC, alginate) in order to produce a primer coated paper web.
  • a surface treatment agent such as for example polyvinyl alcohol, starch, CMC, alginate
  • the primer-coated paper web was dried in an infra-red oven.
  • the dried, primer-coated paper web was re-moisturized to about 15-20% of the solid contents of the paper web.
  • the Gurley value of the remoistened release liner base paper was 669 s.
  • the remoistened release liner base paper was offline super calendered in order to form the glassine base paper.
  • the glassine Base Paper E1-B was manufactured, primer coated and super calendered under the same conditions as described for E1-A, except that 2720 kg of bleached virgin fibers and 750 kg of recycled fibers were dispersed in a pulper.
  • Comparative Example CE1 is a standard glassine that was manufactured, primer coated and super calendered under the same conditions as described for E1-A and E1-B, except that 3470 kg of bleached virgin fibers, comprising a mix of softwood, hardwood and BCTMP, were dispersed in a pulper. Accordingly, CE1 does not contain any recycled fibers.
  • CE1 has been manufactured during the same machine run than E1-A and E1-B. More particularly, the CE1 has been produced just before and just after E1-A and E1-B as represented in Figures 1 and 2 .
  • the glassine Base Papers E1-A, E1-B, and CE1 are produced in Jumbos rolls and the properties of these glassine papers, summarized in Table 1 below, are measured on each Jumbo roll. The values of CE1 are averaged values. Table 1: Properties of Base Papers E1-A, E1-B and CE1.
  • base papers E1-A and E1-B containing 14.3 wt% or 21.4 wt% recycled fibers, respectively, have a more closed structure than the comparative example CE1. This is reflected by the lower air permeability and Rizinus Cobb which implies that samples E1-A and E1-B will absorb less silicone and thus have an improved adherence of the silicone compared to CE1.
  • Comparative Example CE2 is a standard glassine that was manufactured, primer coated and super calendered under the same conditions as described for E2, except that 3470 kg of bleached virgin fibers comprising a mix of softwood, hardwood and BCTMP were dispersed in a pulper. In addition, suspension of fibers has been refining at an energy normally used to produce this grade of paper. That is, the refining energy applied to the suspension of fibers was 11% increased. Comparative Example CE2 does not contain any recycled fibers. CE2 has been manufactured during the same machine run than E2. More particularly, CE2 has been manufactured just before and just after E2 as represented in Figures 3 and 4 . The Gurley value of the remoistened release liner base paper, measured immediately before the step of super calendering, was 718 s.
  • the glassine Base Papers E2 and CE2 are produced in Jumbos rolls and the properties of these papers, summarized in Table 2 below, are measured on each Jumbo roll. The values of CE2 are averaged values. Table 2: Properties of Base Papers E2 and CE2.
  • Technical features Method E2 CE2 Amount [wt%] Recycled Fibers / 14.3 0 Density [g/cm 3 ] ISO 536/ISO 534 1.15 1.15 Air Permeability [pm/Pa ⁇ s] SCAN P26 15996 20020 Transparency [%] DIN 53147 50 50 Basis Weight [g/m 2 ] ISO 536 54 54 Bekk Smoothness [s] back TAPPI T 479 523 556 top 2004 2333 Rizinus Cobb [g/m 2 ] ISO 535 0.9 1.0 Tensile [kN/m] MD ISO 1924 5.50 5.59 CD 2.96 2.90 Tear [mN] MD ISO 1974 327 310 CD 293 297
  • E1-A, E1-B, E2, CE1 and CE2 are used as a base layer to prepare release liners by applying a silicone release coating composition prepared with 100 g Resin W920 (supplied by Wacker ® ), 2.5 g Crosslinker V24 (supplied by Wacker ® ) and 1 g Catalyst OL (platinum based, supplied by Wacker ® ) onto the top side of the release liner base papers. Subsequently, crosslinking is performed by curing the composition for 30 seconds at 140 °C in ventilated drying kiln.
  • Table 3 Properties of release liners obtained from E1-A, E1-B, E2, CE1 and CE2.
  • the overall good properties of the release liner base papers according to the present invention are very surprising considering that recycled cardboard-based and printed material-based fibers are of quite diverse sources that go hand in hand with a wide range in impurities, including silicon-curing poisoning additives.
  • the still good silicone anchoring and crosslinking measured for glassines comprising recycled fibers according to the present invention is surprising.
  • release liner base papers not only can the properties of release liner base papers be maintained when using at least 5 wt% recycled fibers coming from recycled cardboard, printed material or both according to the present invention, air permeability and Rizinus Cobb value are even improved compared to glassine papers not comprising any recycled fibers.
  • the step of refining fibers generally requires high energy. It is applied to improve smoothness and density of the base paper by reducing the average fiber length.
  • the refining energy can be reduced without any deterioration of the desired base paper features (see results of Base Paper E2 below). Accordingly, the method of producing the release liner base paper according to the second aspect of the present invention reduces the refining energy required for the production of release liner base papers while maintaining the high-quality requirements.
  • Release liner base paper comprising recycled fibers, wherein the release liner base paper has a density of at least 1.00 g/cm 3 ,
  • Release liner base paper according to embodiments 1 or 2, wherein the release liner base paper has an air permeability from 100 pm/Pa•s to 70000 pm/Pa•s, preferably from 500 pm/Pa•s to 50000 pm/Pa•s, measured according to SCAN P26 standard.
  • Release liner base paper according to any of embodiments 1 to 3, wherein the release liner base paper has a density of 1.05 g/cm 3 to 1.26 g/cm 3 , preferably of 1.09 g/cm 3 to 1.24 g/cm 3 , more preferably of 1.12 g/cm 3 to 1.22 g/cm 3 .
  • Release liner base paper according to any of embodiments 1 to 4, wherein the release liner base paper has a transparency of 4% to 65%, preferably of 25% to 60%, measured according to DIN 53147 standard, and a basis weight of 30 g/m 2 to 140 g/m 2 , preferably of 45 g/m 2 to 90 g/m 2 , measured according to ISO 536.
  • Release liner base paper according to any of embodiments 1 to 5, wherein the release liner base paper has a Bekk smoothness on the back side of 15 s to 1500 s, preferably of 25 s to 1200 s and on the top side of 400 s to 4000 s, preferably of 500 s to 3500 s, measured according to TAPPI T479 standard.
  • Release liner base paper according to any of embodiments 1 to 6, wherein the release liner base paper has a Rizinus Cobb value of 0.2 g/m 2 to 4 g/m 2 , preferably of 0.3 g/m 2 and 3 g/m 2 , more preferably of 0.6 g/m 2 to 1.4 g/m 2 , measured on the top side according to ISO 535 standard.
  • release liner base paper according to any of embodiments 1 to 7, wherein the release liner base paper further comprises virgin fibers, the virgin fibers comprising at least 10 wt%, or at least 25 wt%, or at least 45 wt%, or at least 70 wt% of bleached chemical pulp based on the total weight of the virgin fibers.
  • Release liner base paper according to any of embodiments 8 to 10, wherein the bleached chemical pulp comprises softwood fibers being present in an amount of at most 50 wt%, preferably at most 25 wt%, based on the total weight of the bleached chemical pulp.
  • Release liner base paper according to any of embodiments 8 to 11, wherein the virgin fibers further comprise at least 2 wt% and less than 50 wt%, preferably 5 to 45 wt%, more preferably 10 to 35 wt% of bleached chemi-thermomechanical pulp, based on the total weight of the virgin fibers.
  • the virgin fibers comprise at least 10 wt%, or at least 25 wt%, or at least 45 wt%, or at least 70 wt% of bleached chemical pulp based on the total weight of the virgin fibers.
  • the bleached chemical pulp comprises hardwood fibers being present in this blend in an amount of at least 50 wt%, preferably at least 75 wt%, based on the total weight of the bleached chemical pulp.
  • the bleached chemical pulp comprises softwood fibers being present in an amount of at most 50 wt%, preferably at most 25 wt%, based on the total weight of the bleached chemical pulp.
  • the virgin fibers further comprise at least 2 wt% and less than 50 wt%, preferably 5 to 45 wt%, more preferably 10 to 35 wt% of bleached chemi-thermomechanical pulp, based on the total weight of the virgin fibers.
  • release liner base paper As a base layer in a method of producing a release liner, the method comprising the steps of applying a release coating composition on at least one side of the release liner base paper, and curing the composition to form a release coating layer.
  • Release liner comprising the release liner base paper according to any of embodiments 1 to 12 as a base layer and a release coating layer on at least one side of the base layer.
  • Laminate comprising the release liner according to embodiments 25 or 26, a face stock and an adhesive layer provided between the release liner and the face stock.

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  • Paper (AREA)
EP22207031.0A 2022-11-11 2022-11-11 Papier de base de doublure détachable à base de fibres recyclées pour application de doublure détachable Withdrawn EP4368773A1 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
EP22207031.0A EP4368773A1 (fr) 2022-11-11 2022-11-11 Papier de base de doublure détachable à base de fibres recyclées pour application de doublure détachable
CN202380074903.1A CN120187918A (zh) 2022-11-11 2023-08-11 用于离型衬垫应用的基于再循环纤维的离型衬垫原纸
EP23755384.7A EP4616028A1 (fr) 2022-11-11 2023-08-11 Papier support de feuille antiadhésive à base de fibres recyclées pour application de feuille antiadhésive
PCT/EP2023/072327 WO2024099607A1 (fr) 2022-11-11 2023-08-11 Papier support de feuille antiadhésive à base de fibres recyclées pour application de feuille antiadhésive
KR1020257014367A KR20250103633A (ko) 2022-11-11 2023-08-11 박리 라이너 적용을 위한 재활용 섬유 기반 박리 라이너 원지

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22207031.0A EP4368773A1 (fr) 2022-11-11 2022-11-11 Papier de base de doublure détachable à base de fibres recyclées pour application de doublure détachable

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EP4368773A1 true EP4368773A1 (fr) 2024-05-15

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EP22207031.0A Withdrawn EP4368773A1 (fr) 2022-11-11 2022-11-11 Papier de base de doublure détachable à base de fibres recyclées pour application de doublure détachable
EP23755384.7A Pending EP4616028A1 (fr) 2022-11-11 2023-08-11 Papier support de feuille antiadhésive à base de fibres recyclées pour application de feuille antiadhésive

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EP23755384.7A Pending EP4616028A1 (fr) 2022-11-11 2023-08-11 Papier support de feuille antiadhésive à base de fibres recyclées pour application de feuille antiadhésive

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EP (2) EP4368773A1 (fr)
KR (1) KR20250103633A (fr)
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Publication number Priority date Publication date Assignee Title
US12473693B2 (en) 2023-02-24 2025-11-18 Upm-Kymmene Corporation BCTMP-tailored SCK paper for release liner
EP4671441A1 (fr) * 2024-06-28 2025-12-31 UPM-Kymmene Corporation Papier de verreine de faible grammage personnalisé bctmp pour doublure détachable

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060191654A1 (en) * 2005-02-25 2006-08-31 John Theisen Paper product and method for manufacturing
WO2009059299A1 (fr) * 2007-11-02 2009-05-07 Wausau Paper Specialty Products, Llc Doublure de libération comportant un revêtement de frottement, un stratifié et procédés de fabrication et d'utilisation de ces derniers
US20120121893A1 (en) 2010-11-12 2012-05-17 Newpage Corporation Better curing coated release liner substrate
EP2539505A1 (fr) 2010-02-23 2013-01-02 Ahlstrom Corporation Support à base de fibres de cellulose contenant une couche de pva modifié et son procédé de production et d'utilisation
WO2020084188A1 (fr) 2018-10-24 2020-04-30 Upm-Kymmene Corporation Doublure anti-adhérente

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110130143A (zh) * 2019-04-26 2019-08-16 吉翔宝（太仓）离型材料科技发展有限公司 一种透气贴合平整的网格状的离型纸

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060191654A1 (en) * 2005-02-25 2006-08-31 John Theisen Paper product and method for manufacturing
WO2009059299A1 (fr) * 2007-11-02 2009-05-07 Wausau Paper Specialty Products, Llc Doublure de libération comportant un revêtement de frottement, un stratifié et procédés de fabrication et d'utilisation de ces derniers
EP2539505A1 (fr) 2010-02-23 2013-01-02 Ahlstrom Corporation Support à base de fibres de cellulose contenant une couche de pva modifié et son procédé de production et d'utilisation
US20120121893A1 (en) 2010-11-12 2012-05-17 Newpage Corporation Better curing coated release liner substrate
WO2020084188A1 (fr) 2018-10-24 2020-04-30 Upm-Kymmene Corporation Doublure anti-adhérente

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EP4616028A1 (fr) 2025-09-17
WO2024099607A1 (fr) 2024-05-16
KR20250103633A (ko) 2025-07-07

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