阅读说明：本技术 辊及其用途 (Roller and use thereof ) 是由 亚尼·图鲁宁 M·科瓦宁 海基·凯图宁 于 2019-03-01 设计创作，主要内容包括：本发明涉及一种用于制造纤维幅材的辊,该纤维幅材包含纤维素纤维。该辊包括具有圆柱形表面的辊体和被布置为覆盖辊体圆柱形表面的辊覆层。该辊覆层包括功能层,该功能层包括聚合物基质和以功能性颗粒和/或功能性纤维形式嵌入聚合物基质中的增强材料。功能性颗粒和/或功能性纤维包含纳米纤维素材料。本发明还涉及辊的用途。(The invention relates to a roll for manufacturing a fibrous web comprising cellulosic fibres. The roll comprises a roll body having a cylindrical surface and a roll cover arranged to cover the cylindrical surface of the roll body. The roll cover includes a functional layer including a polymer matrix and a reinforcing material embedded in the polymer matrix in the form of functional particles and/or functional fibers. The functional particles and/or functional fibers comprise a nanocellulose material. The invention also relates to the use of the roll.)

1. A roll for manufacturing a fibrous web comprising cellulosic fibers, the roll comprising:

-a roller body having a cylindrical surface, and

a roll cover arranged to cover the cylindrical surface of the roll body, the roll cover comprising a functional layer comprising a polymer matrix and a reinforcement material embedded in the polymer matrix in the form of functional particles and/or functional fibers,

wherein the functional particles and/or functional fibers comprise a nanocellulose material.

2. A roll according to claim 1, characterized in that the functional layer comprises 0.05-20 wt. -%, preferably 0.1-10 wt. -%, more preferably 0.5-2 wt. -% of nanocellulose material.

3. A roll according to claim 1 or 2, characterized in that the nano-cellulose material is in the form of fibers or particles.

4. A roll according to claim 1, 2 or 3, characterized in that the nano-cellulose material is selected from cellulose nano-fibrils, nano-crystalline cellulose particles or any mixture thereof.

5. A roll according to any of claims 1-4, characterized in that the nano-cellulose material has at least one dimension, such as length and/or width, of <950 nm.

6. A roll according to claim 3, 4 or 5, characterised in that the nano-cellulose material is in the form of fibres, such as cellulose nano-fibrils, having a length of 300 μm or less, preferably 200 μm or less, and a width of 5-50nm, preferably 5-20 nm.

7. The roller according to any one of claims 3 to 6, characterized in that said nanocellulose material in fiber form is obtained by mechanical treatment selected from high pressure homogenization, grinding or microfluidization.

8. A roll according to claim 3 or 4, characterized in that the nanocellulose material in particle form is obtained by acid hydrolysis with a maximum dimension ≦ 500nm, preferably ≦ 300 nm.

9. A roll according to claim 1, characterised in that the reinforcement material is in the form of fibres made of nanofibrillated cellulose, preferably by spinning.

10. A roll according to claim 9, characterised in that the reinforcement material is in the form of fibres made of nanofibrillated cellulose and has a diameter >15 μ ι η.

11. A roll according to claim 9 or 10, characterised in that the reinforcement material is in the form of fibres made of nanofibrillated cellulose and polymer.

12. A roll according to claim 9, 10 or 11, characterised in that the fibres made of nanofibrillated cellulose are continuous fibres.

13. The roll according to any one of claims 1 to 12, characterized in that the reinforcement material comprising nano-cellulose material comprises surface-modified nano-cellulose material.

14. A roll according to claim 13, characterised in that the reinforcement material comprising nano-cellulose material is surface modified by silanization, silylation, acetylation, esterification, glyoxalation or by grafting of functional groups.

15. A roll according to claim 13 or 14, characterized in that the reinforcement material comprising nano-cellulose material is surface modified by introducing functional groups selected from amino, epoxy, thiocyanate, methacryloxy, vinyl silane and sulfide containing silanes.

16. A roll according to any of claims 1-15, characterized in that the polymer matrix of the functional layer is made of rubber, a thermosetting polymer or a thermoplastic polymer.

17. A roll according to any of the preceding claims 1 to 16, characterized in that the polymer matrix of the functional layer further comprises additional filler particles and/or additives.

18. A roll according to claim 17, characterised in that the sum of the amount of nano-cellulose material and the additional filler particles in the functional layer is 30% by weight or less.

19. A roll according to any of the preceding claims 1 to 18, characterized in that the functional layer further comprises additional reinforcing fibers.

20. Use of a roll according to any one of claims 1 to 19 in a paper, board, toilet or processing machine for a cellulose fibre web.

Technical Field

The present invention relates to a roll and its use according to the preambles of the appended independent claims.

Background

Various polymer-coated rolls are used for the manufacture of fibrous webs, such as webs of paper, paperboard, toilet paper or the like. Rolls may be used in various parts of the manufacturing process, both in paper, board and toilet machines, and in converting machines and finishing machines, such as calenders and coating units. Non-limiting examples of various polymer-coated rolls are calender rolls, coating rolls, reeling cylinders, press rolls and guide rolls.

Conventionally, the roll is coated with one or several polymer layers. Roll covers typically include a polymer matrix that may include various fillers, reinforcing fibers, and/or additives. The mechanical properties of the roll cover are influenced by the polymer matrix itself and the fillers, reinforcing fibers and/or modifiers used. The fillers, fibers, and/or modifiers alter the mechanical properties of the roll cover and thus the roll surface.

The mechanical properties of roll covers used for manufacturing fiber webs are constantly in need of improvement. It would be desirable to find a reinforcing material or modifier that provides roll cover with enhanced mechanical properties and is compatible with a variety of polymer matrices.

Nanostructured cellulosic materials were developed since the 1970 s. Nanostructured cellulose materials can be produced in the form of nanofibrillated cellulose, nanocrystalline cellulose (nanocrystalline cellulose) or bacterial cellulose. Generally, nanostructured cellulosic materials have many advantages and interesting properties, such as strength and viscosity, which motivate their use in various technical fields. For example, nanofibrillated cellulose is used as a thickener and stabilizer in the food industry and as a component of coatings in the paper industry. Nanostructured cellulosic materials have also been used as components of various composite materials. Furthermore, nanostructured cellulose is attractive to the sustainable industry as a renewable biomaterial.

Disclosure of Invention

The object of the present invention is to minimize or even completely eliminate the drawbacks of the prior art.

It is a further object of the present invention to provide a roll with improved mechanical properties, in particular with improved tensile strength, impact strength and/or elongation.

The invention is defined by the characterizing part of the appended independent claim. Some preferred embodiments of the invention are defined in the dependent claims. All the features described, as far as applicable, even if not always, apply to the roll and its application.

A typical roll according to the invention is used for manufacturing a fibrous web comprising cellulosic fibres, the roll comprising:

-a roller body having a cylindrical surface, and

a roll cover arranged to cover the cylindrical surface of the roll body, the roll cover comprising a functional layer comprising a polymer matrix and a reinforcement material embedded in the polymer matrix in the form of functional particles and/or functional fibers,

wherein the functional particles and/or functional fibers comprise a nanocellulose material.

The roll according to the invention is normally used in a paper, board, toilet or processing machine for cellulosic fibre webs.

It has now surprisingly been found that when a reinforcement material in the form of functional particles and/or functional fibers (functional particles and/or functional fibers comprising a nanocellulose material) is incorporated into the polymer matrix of the functional layer, the reinforcement material can improve the mechanical properties of the roll, in particular the tensile strength, impact strength and/or elongation. At the same time, other mechanical properties of the roll, such as tear strength and abrasion resistance, are at least maintained at conventional levels, i.e. the use of nanocellulose material does not reduce these mechanical properties. Furthermore, nanocellulose materials are readily compatible with different polymer matrices. The incorporation of nanocellulose material in the polymer matrix of the functional layer also enables easier processing of the layer, since nanocellulose material can have a positive influence on the matrix viscosity.

According to a preferred embodiment of the invention, a roll for manufacturing a fibrous web comprising cellulosic fibres comprises:

-a roller body having a cylindrical surface, and

-a roll cover arranged to cover a cylindrical surface of a roll, the roll cover comprising a functional layer comprising a polymer matrix and functional particles embedded in the polymer matrix, wherein the functional particles comprise a nano-cellulose material.

In this context, "nanocellulose material" is to be understood as a specific or filamentary cellulose material, at least one dimension of which (for example length and/or width and/or diameter) is in the nanometric size range, i.e. <950 nm. The nanocellulose material is derived from natural starting materials (natural starting materials) containing cellulose. Suitable starting materials are woody materials (e.g. softwood or hardwood) containing cellulose, or non-woody materials (e.g. cotton, kenaf, bamboo, bagasse, flax, hemp, jute, sisal, vegetables or fruits). Woody starting materials are generally preferred.

The nanocellulose material may be in fibrous form or in particulate form. The nanocellulose material suitable for use in the present invention may be selected from cellulose nanofibrils (cellulose nanofibrils), nanocrystalline cellulose particles (nanocrystalline cellulose particles), or any mixture thereof. The cellulose nanofibrils comprise both crystalline and amorphous regions in their structure, whereas the amorphous regions have substantially or completely disappeared from the structure of the nanocrystalline cellulose particles. Cellulose nanofibrillar fibers and nanocrystalline cellulose particles differ from each other by their mechanical properties (e.g. stiffness). Depending on the properties required for the roll cover, cellulose nanofibrils, nanocrystalline cellulose or any mixture thereof may be used.

According to one embodiment, as mentioned above, the nanocellulose material used comprises cellulose nanofibrils, which are obtained by mechanical treatment of a starting material containing cellulose. The nano-cellulose material is in the form of fibers, such as cellulose nano-fibrils, and may be obtained by mechanical treatment, which may be selected from high-pressure homogenization (high-pressure homogenization), grinding (grinding) or microfluidization (microfluidization). The cellulose-containing starting material may be pretreated by refining or low temperature crushing (cryo-crushing) prior to mechanical treatment. Alternatively or additionally, the starting material may be pretreated enzymatically or chemically, for example by TEMPO oxidation.

The length of the nanocellulose material in the form of fibres (e.g. cellulose nanofibrils) may be >4 μm. According to a preferred embodiment, the nanocellulose material is in the form of fibres, such as cellulose nanofibrils, which may have a length of ≦ 300 μm, preferably ≦ 200 μm, and a width of 5-50nm, preferably 5-20 nm.

According to one embodiment of the invention, the nanocellulose material in particle form is obtained by acid hydrolysis and has a maximum dimension of ≦ 500nm, preferably ≦ 300 nm. The nanocellulose material in particle form obtained by acid hydrolysis is called nanocrystalline cellulose.

The reinforcement material may be in the form of functional fibres made of nanofibrillated cellulose, preferably by spinning or drawing. The functional fibers may be made from nanofibrillated cellulose alone or may be made from nanofibrillated cellulose and any suitable polymer such as polyvinyl alcohol, polypropylene, polyethylene, poly (lactic acid) or cellulose acetate butyrate. If the functional fibers are formed from nanofibrillated cellulose only, various solution methods are available and known for fiber formation, such as wet spinning, dry spinning or flow focusing. If the functional fibers are formed by using both nanofibrillated cellulose and a polymer, the fibers may be formed by using melt spinning or solution spinning (e.g., dry spinning or wet spinning).

The functional fibers may be made as continuous fibers from a starting material comprising nanofibrillated cellulose. The resulting functional fibers are not necessarily perfectly round. The diameter is the longest distance between two points on the circumference of the fiber, the straight line between which passes through the center of the cross-section of the fiber. According to one embodiment, the reinforcement material in fiber form and made of nanofibrillated cellulose has a diameter >15 μm, preferably 15-350 μm, more preferably 20-300 μm.

According to one embodiment of the invention, the functional layer comprises a reinforcement material in the form of both functional particles and functional fibers, wherein both the functional particles and the functional fibers comprise a nano-cellulose material.

According to one embodiment of the invention, the reinforcement material in the form of functional particles and/or functional fibers comprises a nano-cellulose material, including a surface-modified nano-cellulose material. The nanocellulose material may be surface modified by silylation, acetylation, esterification, glyoxalation or by grafting of functional groups. Preferably, the nanocellulose material is modified by silanization. For example, the nanocellulose material may be surface modified by introducing a functional group selected from the group consisting of amino, epoxy, thiocyanate, methacryloxy, vinyl silane and sulfide-containing silane, wherein the functional group is coupled to the nanocellulose material surface, for example, by silanization. According to one embodiment, the nanocellulose material may be either amino silanized or epoxy silanized. The surface modification improves the interaction between the surface of the nanocellulose material and the surrounding functional layer polymer matrix. In this way, the chemical compatibility between the nano-cellulose material and the surrounding polymer matrix, and thus the mechanical properties of the roll cover, can be improved. The surface modification of the nanocellulose material also enables it to be compatible with different polymer matrices. If the reinforcing material is in the form of functional fibers made of nanofibrillated cellulose, the surface of the functional fibers may be modified after they are formed into fibers, for example by spinning or drawing.

The functional layer typically comprises a polymer matrix and a reinforcement material comprising a nano-cellulose material embedded in said polymer matrix. The functional layer may have a thickness of 5-40 mm. The nano-cellulose material may be substantially uniformly distributed in the polymer matrix, i.e. the functional layer. This means that the concentration of nano-cellulose material and optionally other filler particles and/or additional fibres (as described below) is the same in both the inner and outer surfaces of the functional layer and throughout the layer. Preferably, all particles and fibres in the functional layer, including nano-cellulose material and optional additional filler particles, are uniformly distributed in the axial and circumferential direction of the roll.

The nanocellulose material may also be used in the form of continuous reinforcing fibres, which may be impregnated with the polymer material and then wound on a roll, or in the form of a non-woven felt or as a component in a non-woven fibre felt. Continuous fibers made from nanofibrillated cellulose may have ultimate strength properties per cross-sectional area and, due to their small diameter, the fibers are firmly bonded to the polymer matrix, thus providing excellent smoothness to the roll cover in addition to good strength properties.

According to one embodiment of the invention, the polymer matrix of the functional layer may be made of rubber, a thermosetting polymer or a thermoplastic polymer. Suitable rubbers are, for example, natural rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, Ethylene Propylene Diene (EPDM) rubber, chlorosulfonated polyethylene (CSM) rubber, and any mixtures thereof. Suitable thermosetting polymers are, for example, various polyurethane resins and epoxy resins. Suitable thermoplastic polymers, although less commonly used, are, for example, fluorothermoplastic polymers and polyphenylene sulfides, polyetherketones, polyetheretherketones, polyphthalamides, polyamides, polyetherimides, polyethersulfones, polysulfones, and any mixtures thereof.

According to one embodiment of the invention, the functional layer may comprise 0.05-20 wt% (0.05-20 weight%, 0.05-20 wt%), preferably 0.1-10 wt%, more preferably 0.5-2 wt% of nanocellulose material.

The polymer matrix of the functional layer may also comprise additional filler particles and/or additives. The polymer matrix may contain one type of additional filler particles, or the polymer matrix may contain a plurality of different additional filler particles. For example, the polymer matrix may comprise the second, third and any subsequent additional filler particles. The additional filler particles may be selected from inorganic particles, such as particles of silica, silicon carbide, carbon black, titanium oxide, feldspar, kaolin; or from organic particles, such as particles of aramid or polyethylene or rubber. In some embodiments, the additional filler particles may have an average particle diameter (average particle diameter) of more than 5 μm, preferably in the range of 10-300 μm. It is also possible to use nano-sized additional filler particles having an average particle size of <1 μm, for example 5-40 nm. The nano-sized additional filler particles may be used alone or with larger additional filler particles. By using one or more additional filler particles, the mechanical properties of each or any layer of the roll cover can be adjusted in a suitable, flexible and cost-effective manner. However, the use of additional filler particles in the present invention is entirely optional.

In case the functional layer comprises additional filler particles, the amount of nano-cellulose material in the functional layer may be about 1 wt%, e.g. 0.5-1.5 wt%. The total amount of nano-cellulose material and additional filler particles in the functional layer is typically 30 wt. -%. The total weight represents the dry weight of the nanocellulose material and the additional filler particles.

According to one embodiment of the invention, the functional layer comprises only nanocellulose material and does not comprise any other additional inorganic and/or organic filler particles, except possibly pigment particles.

In addition to the functional particles or functional fibers comprising the nanocellulose material, the polymer matrix of the functional layer may also comprise additional reinforcing fibers, such as glass, nylon, carbon, polyester or aramid fibers. The functional layer may also contain two or more different types of additional reinforcing fibers.

Drawings

Some embodiments of the invention are explained in more detail in the following schematic non-limiting figures, in which

Figure 1 shows a press roll arrangement in a paper or board machine, and

fig. 2 shows a more detailed view of the roll and roll cover.

Detailed Description

Figure 1 shows a press roll arrangement in a paper or board machine. Two parallel rolls 10, 20 are adjacent to each other and form a nip N between them. One or both of the rollers 10, 20 may be loaded against each other. The rolls 10, 20 may be rolls of a calender, a press, a coater or a size press. The web W of paper or board is passed through the nip N without or with support from belts or felts. Both rolls have a metal body or shell 1 and at least one of them has a cover 2 made of a polymer and arranged to surround the metal body or shell 1.

Fig. 2 shows a more detailed view of the roll and roll cover. The coating 2 comprises at least a functional layer 3, which functional layer 3 is the outermost layer of the coating 2 and provides the surface for the metal body 1 of the roll. During the manufacturing process of paper or board, the functional layer 3 is in contact with the fibrous web or the fabric supporting the fibrous web, and is therefore exposed to wear and pressure from the environment. The functional layer 3 comprises at least nanocellulose particles and optionally also other additional fillers and reinforcing fibres.

Beneath the functional layer 3 there may be one or more intermediate layers 4, which are adhesive layers between the metallic body 1 and the functional layer 3. The intermediate layer 4 may also provide other tailored properties of the coating 2, for example in terms of graded hardness, thermal conductivity, etc. The intermediate layer 4 may comprise a fibre-reinforced material. One or more of the intermediate layers 4 may also include at least one filler. The filler in the intermediate layer may be the same as or different from the filler in the functional layer 3. In the case of two or more intermediate layers, the filler in each intermediate layer may be the same or different. The amount of filler in the intermediate layer 4 is preferably lower than the amount of filler in the functional layer 3.

Experiment of

Some embodiments of the invention are described in the following non-limiting examples, in which different filler compositions are used to test the coating composition for calender or applicator rolls.

Examples 1 and 2

Two samples of simulated calender roll coverings without reinforcing fibers were prepared. A resin composition was prepared comprising bisphenol F epoxy resin, diethyltoluenediamine (diethyl toluene diamine) hardener, and 0.5phr tertiary amine accelerator. The resin compositions in example 1 and example 2 were the same.

In example 2, aminosilane-modified Cellulose Nanocrystals (CNC) were added by high shear mixing and sonication in an amount of 1 wt% of the total weight of the resin composition. The CNC used was purchased as a spray-dried powder from the university of maine with a fiber width of 5-20nm and a fiber length of 150-200nm, depending on the product specification. The CNC is dispersed in the resin composition and the CNC/resin dispersion thus obtained is degassed before being mixed with the hardener.

The two resin compositions thus obtained were applied to a mold in a thickness of 12 mm. The samples were cured at a temperature of 150 ℃ for 8 hours. The cured samples were subjected to multiple mechanical tests. The wear test was carried out according to the rubber wheel wear test modified slightly by the standard ASTM G65, with the unit of material loss being mm³in/Nm. Other tests performed are hardness (measured as shore D hardness), tensile strength, elongation at break and impact strength (measured as charpy impact test). In table 1, the measured values according to an embodiment of the present invention (example 2) are given in percentage with respect to example 1, which is a reference example of an unfilled material without CNC. A negative percentage of the wear value indicates that the surface is less susceptible to wear, which is desirable. A positive percentage of elongation and impact strength indicates that the surface has better strength properties, which is desirable.

Example 3 and example 4

Two samples were prepared simulating the sizer roll cover. A polyurethane composition was prepared by mixing an MDI-terminated polyether prepolymer having an NCO content of 11.5%, 30phr of PTMEG polyol having an average molecular weight of 2000g/mol and 1, 4-butanediol as the main hardener, and had a stoichiometric index of 105. In examples 3 and 4, the polyurethane compositions were the same.

In example 4, aminosilane-modified Cellulose Nanocrystals (CNC) were added by high shear mixing and sonication in an amount of 1 wt% of the total weight of the polyurethane composition. The CNC used was purchased as a spray-dried powder from the university of maine with a fiber width of 5-20nm and a fiber length of 150-200nm, depending on the product specification. The CNC was dispersed in PTMEG and the dispersion was degassed prior to mixing with the prepolymer and 1, 4-butanediol.

Example 3 represents a comparative example, and example 4 represents an embodiment according to the present invention. The polyurethane composition obtained was cast and cured at 130 ℃ for 18 hours. The abrasion test was carried out according to DIN 53516 and the material loss is in mm³. The tear strength is measured according to standard ISO 34-1, method B, step (B), (standard ISO 34-1, method B, procedure (B)). The measured values of the comparative test (example 3) are given in table 1 as absolute values, whereas the values of embodiment 4 according to the invention are given as percentages relative to comparative example 3. A negative percentage of the wear value indicates that the surface is more wear resistant, which is desirable. Positive values for tensile strength, elongation at break and tear strength indicate that the material is mechanically stronger, which is desirable.

As can be seen from the results of table 1, improvements can be obtained by the roll cover composition comprising modified cellulose nanocrystals. In particular, both the impact strength values of the epoxy resins and the mechanical strength values of the polyurethanes show good and unexpected improvements.

When testing the dynamic behavior of tan (tan-delta) as a function of temperature, it was found that polyurethane roll covers according to the invention and comprising modified cellulose nanocrystals behave very similar, almost identical, to unfilled roll covers. From all the tests carried out it can be concluded that all the basic properties of the roll cover are improved without compromise, which is difficult to achieve with only a single raw material.

Even though the invention has been described with reference to what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment, but it is intended to cover various modifications and equivalent technical solutions falling within the scope of the appended claims.

Table 1 results of examples 1 to 4

(C) Comparative example, no CNC