Roll cover and its use

Abstract

The invention relates to a roll for use in a manufacture of a fibrous web comprising cellulosic fibres. The roll comprises a roll body with a cylindrical surface, and a roll cover, which is arranged to cover the cylindrical surface of the roll body, the cover comprising a functional layer, which comprises a polymer matrix and filler particles and / or reinforcing fibres embedded in the polymer matrix. At least one functional layer constituent selected from filler particles, reinforcing fibres, and polymer matrix comprises material originating from recycled raw material(s).

Description

[0001] The present invention relates to a roll and its use according to the preambles of the enclosed independent claims.

[0002] Various polymer coated rolls are used in manufacture of fibrous webs, such as webs of paper, board, tissue, or the like. Rolls can be used in several parts of the manufacturing process, both in paper, board, and tissue machines, as well as in converting and finishing machines, such as calendars and coating units. Nonlimiting examples of various polymer coated rolls are calender rolls, coater rolls, reeling drums, press rolls and guide rolls.

[0003] Conventionally the rolls are coated with one or several polymer layers. Roll cover typically comprises a polymer matrix, where various fillers, reinforcing fibres and / or additives may be included. Roll covers used in paper, board, tissue, and pulp making need periodical renewal and thus consume tonnes of material resources. A major part of the raw materials used in roll covers - polymers, resins, and other industrial chemicals - has traditionally been manufactured from fossil-based raw materials and refined and processed from crude oil. The manufacturing methods for these raw materials may also have been energy consuming. Old roll covers have ended up in landfill or as energy waste.

[0004] In view of the increasing requirements for sustainability, emerging interest in circular economy as well as desired to reduce fossil-based raw materials there is a need for novel roll covers that meet these expectations without sacrificing their mechanical performance.

[0005] DE 20 2012 012 489 U1 discloses a roll cover, especially for treating of a paper, board, tissue or other fibrous web in a production and / or finishing machine. The roll cover comprises at least one layer which has a matrix composed of at least one rubber, in which particles of a first polymer are embedded At least some of the particles of the first polymer are covalently bonded to the matrix. Particles can be produced from recycled material.

[0006] An object of this invention is to minimise or even totally eliminate the disadvantages existing in the prior art.

[0007] Another object of the invention is to provide a roll with good mechanical properties which can be produced in sustainable manner.

[0008] The invention is defined in the characterising parts of the enclosed independent claims. Some preferable embodiments of the invention are defined in the dependent claims. All described features apply both for the roll as well as its use, whenever applicable, even if it not necessarily always stated so.

[0009] A typical roll according to present invention for use in a manufacture of a fibrous web is defined in claim 1, and comprises, inter alia, a roll body with a cylindrical surface, and a roll cover, which is arranged to cover the cylindrical surface of the roll body, the cover comprising a functional layer, which comprises a polymer matrix and filler particles and / or reinforcing fibres embedded in the polymer matrix, wherein at least one functional layer constituent selected from filler particles, reinforcing fibres, and polymer matrix comprises material originating from recycled raw material(s).

[0010] Typical roll according to the present invention is used in a paper machine, board machine, tissue machine or in a converting machine for a fibrous cellulosic web.

[0011] Typical use of filler material, reinforcing fibres and / or polymer matrix originating from recycled material is for manufacturing a roll cover of a roll for use in a manufacture of a fibrous web comprising cellulosic fibres.

[0012] Now it has been surprisingly found that a roll cover where at least one of the functional layer constituents selected from filler particles, reinforcing fibres and polymer matrix comprises, preferably at least 40 weight-%, material originating from recycled raw material(s), shows at least acceptable mechanical properties or even as good mechanical properties as the conventional roll covers. The present invention provides a giant leap toward a more holistic approach with a focus on sustainability in the roll cover manufacture. It enables replacement of as many of the roll cover raw materials as possible with more sustainable recycled alternatives. The present invention uses recycled materials and optionally also renewable resources, saves energy, and minimizes the dependency on crude oil in roll cover manufacture.

[0013] Even if the roll covers according to the present invention comprise a major amount of recycled material(s), and also bio-based raw material(s) and optionally carbon-dioxide based raw material(s), their user safety is not compromised, on the contrary. Safety has always been a high priority in roll cover manufacture, and over the years raw materials has been replaced in roll cover production with safer alternatives. Raw material selection has been heavily guided by worker safety. For example, reinforcing silica filler particles, which are used conventionally and which may be hazardous for the manufacturing workers may be replaced by ground recycled glass by using the present invention.

[0014] The rolls according to the present invention with sustainable roll covers have shown surprising laboratory results. The mechanical properties of the roll covers are at least acceptable, often as good as the mechanical properties obtainable with use of virgin raw materials. Some of the mechanical properties, like wear resistance, may be even better than with conventional roll covers. This shows that at least some of the raw materials can be replaced with more sustainable options when using the materials originating from recycled raw material(s).

[0015] According to one embodiment of the invention the roll for use in a manufacture of a fibrous web comprises a roll body with a cylindrical surface, and a roll cover, which is arranged to cover the cylindrical surface of the roll body, the cover comprising a functional layer, which comprises a polymer matrix, wherein the roll cover comprises at least 50 % of recycled and / or bio-based raw materials.

[0016] According to one embodiment a roll for use in a manufacture of a fibrous web comprises a roll body with a cylindrical surface, and a roll cover, which is arranged to cover the cylindrical surface of the roll body, the cover comprising a functional layer, which comprises a polymer matrix. wherein the roll cover comprises at least 40 weight-% of material originating from recycled raw material(s) and / or bio-based raw material(s) and / or carbon dioxide-based polymeric material(s).

[0017] According to one preferable embodiment the total amount of recycled raw material(s) and / or biobased raw material(s) and / or carbon dioxide based polymeric material(s) in the roll cover may be at least 40 weight-%. It is possible that the total amount of recycled raw material(s) and / or bio-based raw material(s) and / or carbon dioxide based polymeric material(s) in the roll cover may be at least 50 weight-% or at least 75 weight-%, preferably at least 80 weight-%, more preferably at least 90 weight-%, sometimes even 100 weight-%. In some embodiments the roll cover may comprise between 50 and 100 weight-%, or between 75 and 96 weight- %, or between 75 and 100 weight-%, of material originating from recycled material(s) and / or bio-based raw material(s). The percentages are calculated based on the total weight of the roll cover. It is highly surprising that the roll cover can comprise such amounts recycled and / or sustainable material(s).

[0018] The roll cover may comprise recycled consumer plastic or recycled glass as the reinforcing fibre or filler in composite roll covers. According to one embodiment of the invention the functional layer may comprise filler particles embedded in the polymer matrix, the filler particles comprising recycled glass particles. According to one embodiment the functional layer comprises solely filler particles which are made of recycled glass. The recycled glass may be calcium aluminosilicate glass obtained from post-industrial and / or post-consumer glass feedstocks. Recycled glass may comprise 50 - 55 % of SiO 2 , 14 - 20 % of Al 2 O 3 , 20 - 25 % of CaO and 8 - 14 % of Na 2 O+K 2 O. The d 50 particle size of the recycled glass filler particles may be in a range of 1 - 300 µm, preferably 5 - 40 µm.

[0019] According to one embodiment the functional layer may comprise filler particles originating from recycled roll covers and / or recycled rubber products. The filler particles can be obtained by grinding old roll covers and discarded rubber products to desired particle size.

[0020] The functional layer may comprise reinforcing fibres comprising fibres made of recycled consumer plastic or recycled glass. According to one preferable embodiment the reinforcing fibres are recycled polymeric fibres. For example, the reinforcing fibres may comprise fibres made of recycled polyethylene terephthalate, originating e.g. from recollected consumer drinking bottles. According to another embodiment the reinforcing fibres may comprise fibres made of recycled polyester, originating e.g. for consumer textile waste or other recollected plastic waste. The thickness of the reinforcing fibres, especially when made of recycled plastic material, such as recycled polyester, may be in the range of 0.1 - 100 µm, preferably 1 - 50 µm, more preferably 3 - 20 µm, even more preferably 5 - 15 µm.

[0021] According to one embodiment of the present invention the filler material, reinforcing fibres and polymer matrix may further comprise material originating from bio-based raw material(s.) In the present context "bio-based raw material" denotes preferably renewable materials derived from non-food chain plants and / or plant parts, cultivated in sustainable manner. According to this embodiment the use of bio-based raw materials does not affect global food production, and the cultivation and harvesting of plants do not endanger the growth of natural forests either. In an even more preferable embodiment, bio-based raw material may be produced from plant parts that would otherwise be waste, such as lignin. In some embodiments, bio-based raw material may even comprise renewable materials derived from food chain plants and / or plants parts or a mixture of non-food chain plants and food chain plants.

[0022] According to one embodiment the functional layer may comprise filler particles embedded in the polymer matrix, the filler particles comprising particles made of lignin, micro-fibrillated cellulose or nanocellulose. Nanocellulose particles and nanocellulose particular material, as well micro-fibrillated cellulose particles which are suitable for use as filler particles, originates from natural cellulose containing starting material. Suitable starting materials are cellulose containing wood materials, such as softwood or hardwood, or non-wood materials, such as cotton, kenaf, bamboo, bagasse, flax, hemp, jute, sisal, vegetables, or fruits. Wood based starting materials are usually preferable for the nanocellulose particular material as well as for micro-fibrillated cellulose particles.

[0023] In one embodiment the reinforcing fibres may comprise fibres of natural origin, selected from cotton fibres, flax fibres, hemp fibres, or any of their mixture. It has been observed that reinforcing fibres of natural origin may provide similar or even better results than conventional synthetic virgin fibres used as reinforcing fibres. This is unexpected and provides new possibilities for increasing the amount of bio-based materials in the roll cover.

[0024] According to one embodiment of the invention the functional layer may comprise carbon black made of lignin and / or carbon black made of recycled rubber products and / or recycled roll covers. Carbon black can be produced from lignin by carbonization at elevated temperature and milling. It has been observed that the obtained material is well suited for replacing conventional carbon black. Lignin is widely available as by-product from pulp and paper industry and from production of bioethanol. When carbon black is made from recycled rubber products and / or recycled roll covers the present invention enables use of the scrap material from removed roll covers or discarded rubber products to be optimally recycled or utilized. Used roll covers and rubber products can be transformed into carbon black by using pyrolysis processes intended for breaking the rubber tires down back to oil, carbon black and fuel. In this manner the carbon black from the old roll covers and discarded rubber products can be recycled to produce new rubber roll covers.

[0025] According to one embodiment bio-based resin and / or hardener may be used in the polymer matrix. For example, bio-based resin made from cashew nutshell oil can be used in the polymer matrix as an epoxy resin hardener. Cashew nutshell oil is a non-edible waste product, which is well-suited for providing sustainable bio-based resin. Alternatively, epoxy resin can be prepared from bio-based glycerol obtained for example as by-product from biodiesel production.

[0026] According one embodiment the polymer matrix of the functional layer is made of natural rubber.

[0027] According to one embodiment the roll cover, especially polymer matrix of the functional layer, may comprise carbon dioxide-based polymeric material. The roll cover may comprise, for example, carbon dioxide-based aliphatic or aromatic polycarbonates, such as carbon-dioxide based polypropylene ether carbonate or carbon-dioxide polyethylene carbonate, or polyurethane that is synthesized from these or other carbon-dioxide polyols. Use of carbon-dioxide based polymeric material in manufacture of roll cover enables the increase of the amount of renewable material in an unexpected manner.

[0028] According to one embodiment the polymer matrix of the functional layer can be polyurethane made of polyols and isocyanates of natural origin, for example of carbon-dioxide based polyols and isocyanates of natural plant-based origin. It is also possible to make the polymer matrix of the functional layer from polyurethane, which is obtained through non-isocyanate polyurethane synthesis employing carbon dioxide-based polyols, plant oils, fatty acids and / or biomass-based platform chemicals.

[0029] According to one embodiment the functional layer may preferably comprise at least two of the following: recycled glass particles, recycled polymeric fibres and natural fibres selected from cotton fibres, flax fibres, hemp fibres, and their mixtures.

[0030] According to one preferable embodiment the roll is used as press roll, suction roll, sizer roll, guide roll, coater roll and / or calender roll in manufacture of paper, board, tissue, or the like. It has been observed that the most important roll cover properties and requirements - for example, in the results achieved in pressing or calendering - are at least as good as with conventional rolls and the users do not need to compromise on product performance.EXPERIMENTAL

[0031] Some embodiments of the invention are described in the following nonlimiting examples, where roll cover compositions for calender rolls were tested using varying filler compositions.Example 1

[0032] Two samples simulating calender roll cover were prepared. The first resin composition comprised bisphenol-F epoxy resin, diethyl toluene diamine hardener and silica filler (Sikron M600, Saint-Gobain). The second resin composition comprised bisphenol-F epoxy resin, diethyl toluene diamine hardener and recycled glass powder filler (LA800, Vitro Minerals). The filler content was 30 weight-% of the epoxy weight in both samples and the fillers were dispersed in the resin by high-shear mixing. The obtained resin-filler dispersion was degassed prior to the mixing with the hardener.

[0033] A first non-woven polyester veil made of virgin polyester fibres and a second polyester veil made of recycled polyester fibres were obtained from Norafin Industries. The first polyester veil was wetted with the first resin composition and the second polyester veil was wetted with the second resin composition. Layers of the wetted first veil were laminated together to form a first laminate plate. Layers of the wetted second veil were laminated together to form a second laminate plate. The first and the second laminate plates were 12 mm thick. The laminate plates were cured at a temperature of 150 °C for 8 hours. Several mechanical tests were performed to the laminate plates. The wear test was performed as a rubber wheel wear test slightly modified from standard ASTM G65 giving material loss in mm3 / Nm. Other tests performed were hardness, measured as Shore D hardness, tensile strength, elongation at break and impact strength, measured as Charpy impact test.

[0034] The results of Example 1 are given in Table 1. The second laminate plate is according to the present invention and comprises recycled glass as filler and recycled polyester fibres. The first laminate plate is a reference laminate plate made from virgin raw materials. Table 1 Results of Example 1.Property1 st< Laminate Plate (reference)2 nd< Laminate PlateHardness [ShD]88.388.3Modulus E' at 60 °C [MPa]41704200Tensile strength [MPa]5045Elongation at break [%].1.61.2Charpy impact strength [kJ / m 2< ]6.35.3Rubber wheel wear rate [mm 3< / Nm]0.00680.0073

[0035] It can be seen from results in Table 1 that even though the mechanical strength of the 2 nd< laminate plate, made with recycled raw materials, is somewhat weaker than that of the reference laminate plate, the difference is not significant.Example 2

[0036] Two samples simulating calender roll cover were prepared. The first resin composition comprised bisphenol-F epoxy resin, diethyl toluene diamine hardener and silica filler (Sikron M600, Saint-Gobain). The second resin composition comprised bisphenol-F epoxy resin, diethyl toluene diamine hardener and recycled glass powder filler (LA800, Vitro Minerals). The filler content was 10 weight-% of the epoxy weight in both samples and the fillers were dispersed in the resin by high-shear mixing. The obtained resin-filler dispersions were degassed prior to the mixing with the hardener.

[0037] A non-woven polyester veil made of virgin polyester fibres and a non-woven flax veil made of flax fibres were obtained from Norafin Industries. The polyester veil was wetted with the first resin composition and the flax veil was wetted with the second resin composition. Layers of the wetted first veil were laminated together to form a first laminate plate, 12 mm thick. Layers of the wetted second veil were laminated together to form a second laminate plate, 8 mm thick. The laminate plates were cured at a temperature of 150 °C for 8 hours. Several mechanical tests were performed to the laminate plates. The wear test was performed as a rubber wheel wear test slightly modified from standard ASTM G65 giving material loss in mm3 / Nm. Other tests performed were hardness, measured as Shore D hardness, tensile strength, elongation at break and impact strength, measured as Charpy impact test.

[0038] The results of Example 2 are given in Table 2. The second laminate plate is according to the present invention and comprises recycled glass as filler and flax fibres. The first laminate plate is a reference laminate plate made from virgin and oil-based raw materials. Table 2 Results of Example 2Property1 st< Laminate Plate (reference)2 nd< Laminate PlateHardness [ShD]88.289.1Modulus E' at 60 °C [MPa]30005800Tensile strength [MPa]61.686.3Elongation at break [%]3.01.9Charpy impact strength [kJ / m 2< ]13.113,2Rubber wheel wear rate [mm 3< / Nm]0.00570.0054

[0039] It can be seen from results in Table 2 that the more sustainable material options (2 nd< laminate plate) give stiffer and stronger material than the reference laminate plate.

[0040] Even if the invention was described with reference to what at present seems to be the most practical and preferred embodiments, it is appreciated that the invention shall not be limited to the embodiments described above, but the invention is intended to cover also different modifications and equivalent technical solutions within the scope of the enclosed claims.

Claims

1. A roll for use in a manufacture of a fibrous web comprising cellulosic fibres, the roll comprising - a roll body with a cylindrical surface, and - a roll cover, which is arranged to cover the cylindrical surface of the roll body, the cover comprising a functional layer, which comprises a polymer matrix and filler particles and / or reinforcing fibres embedded in the polymer matrix, characterized in that at least one functional layer constituent selected from filler particles, reinforcing fibres, and polymer matrix comprises material originating from recycled raw material(s) and biobased raw material(s), wherein the total amount of recycled raw material(s) and / or biobased raw material(s) in the roll cover is at least 40 weight-%.

2. Roll according to claim 1, characterized in that the filler particles comprise particles made of lignin, nanocellulose and / or microfibrillar cellulose.

3. Roll according to claim 1 or 2, characterized in that the reinforcing fibres comprise fibres of natural origin, which are selected from cotton fibres, flax fibres, hemp fibres or any of their mixture.

4. Roll according to any of preceding claims 1 - 3, characterized in that the polymer matrix comprises carbon dioxide based polymeric material.

5. Roll according to claim 4, characterized in that the total amount of recycled raw material(s) and / or biobased raw material(s) and / or carbon dioxide based polymeric material(s) in the roll cover is at least 40 weight-%.

6. Roll according to claim 5, characterized in that the total amount of recycled raw material(s) and / or bio-based raw material(s) and / or carbon dioxide based polymeric material(s) in the roll cover is at least 50 weight-%, preferably at least 75 weight-%, more preferably at least 80 weight-%, even more preferably at least 90 weight-%.

7. Roll according to any of preceding claims 1 - 6, characterized in that the filler particles comprise recycled glass particles, and / or particles originating from recycled roll covers and / or recycled rubber products.

8. Roll according to any of preceding claims 1 - 7, characterized in that the functional layer comprises carbon black made of lignin and / or carbon black made of recycled roll covers and / or recycled rubber products.

9. Roll according to any of preceding claims 1 - 8, characterized in that that the reinforcing fibres comprise fibres made of recycled consumer plastics or recycled glass, the reinforcing fibres comprising preferably fibres made of recycled polyethylene terephthalate or recycled polyester.

10. Roll according to claim 1, characterised in that the functional layer comprises at least two of the following: recycled glass particles, recycled polymeric fibres and natural fibres selected from cotton fibres, flax fibres, hemp fibres, and their mixtures.

11. Roll according to any of preceding claims 1 - 10, characterised in that the polymer matrix of the functional layer is made of natural rubber.

12. Roll according to any of preceding claims 1 - 11, characterised in that the polymer matrix of the functional layer is polyurethane made of polyols and isocyanates of natural origin.

13. Roll according to any of preceding claims 1 - 12, characterised in that a bio-based resin and / or hardener is used in the polymer matrix.

14. Roll according to any of preceding claims 1 - 13, characterised in that the roll is a press roll, suction roll, sizer roll, calander roll or a coater roll.

15. Use of a roll according to any of claims 1 - 14 in a paper machine, board machine, tissue machine or in a converting machine for a fibrous cellulosic web.