• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a waterborne adhesive comprising crosslinkable microfibrillated cellulose (MFC), as well as a method for adhering surfaces together using said adhesive.
    公开号:SE1850727A1
    申请号:SE1850727
    申请日:2018-06-13
    公开日:2019-12-14
    发明作者:Gisela Cunha；Lena Lönnemark
    申请人:Stora Enso Oyj；
    IPC主号:
    专利说明:

    WATERBORNE ADHESIVE COMPRISING CROSSLINKABLE MICROFIBRILLATED CELLULOSE The present invention relates to a Waterborne adhesive comprising crosslinkablemicrofibrillated cellulose (MFC), as well as a method for adhering surfaces together using said adhesive.
    BACKGROUND Waterborne adhesives are becoming increasingly popular, since they represent anenvironmentally friendly and economically viable alternative to solvent-based counterparts.However, the performance of current paper and/or wood Waterborne adhesives based onnatural sources, such as starch or proteins, is reduced under moist conditions, due to theintrinsic water sensitivity of these natural sources, especially if no external crosslinker is added to the formulation.
    On the other hand, Waterborne adhesives With high wet performance usually consist oflatexes comprising fossil-fuel based monomers; this is the case for synthetic rubbers,polyacrylates and polyurethanes. It is therefore desirable to develop Waterborne adhesives with improved performance in moist conditions and which are based on natural sources.
    Microfibrillated cellulose (MFC) comprises partly or totally fibrillated cellulose or lignocellulosefibers. The liberated fibrils have a diameter less than 100 nm, whereas the actual fibrildiameter or particle size distribution and/or aspect ratio (length/width) depends on thesource and the manufacturing methods. The smallest fibril is called elementary fibril and hasa diameter of approximately 2-4 nm (see e.g. Chinga-Carrasco, G., Nanoscale researchletters 2011, 6:417), while it is common that the aggregated form of the elementaw fibrils,also defined as microfibril, is the main product that is obtained when making MFC e.g. byusing an extended refining process or pressure-drop disintegration process (see Fengel, D.,Tappi J., March 1970, Vol 53, No. 3.). Depending on the source and the manufacturingprocess, the length of the fibrils can vary from around 1 to more than 10 micrometers. Acoarse MFC grade might contain a substantial fraction of fibrillated fibers, i.e. protrudingfibrils from the tracheid (cellulose fiber), with a certain amount of fibrils liberated from the tracheid (cellulose fiber).
    There are different acronyms for MFC such as cellulose microfibrils, fibrillated cellulose,nanofibrillated cellulose, fibril aggregates, nanoscale cellulose fibrils, cellulose nanofibers,cellulose nanofibrils, cellulose microfibers, cellulose fibrils, microfibrillar cellulose, microfibril aggregrates and cellulose microfibril aggregates. MFC can also be characterized by various physical or physical-chemical properties such as large surface area or its ability to form a gel- like material at low solids (1-5 Wt%) when dispersed in water.
    MFC exhibits useful chemical and mechanical properties. Chemical surface modification ofMFC has the potential to improve the properties of MFC itself, e.g. mechanical strength and water absorbance and - in certain circumstances - elasticity/flexibility.
    Patent publications in this field include US20090298976, US2017183820, JPHO63398 andJP2017189164.
    SUMMARY It has been verified that when an aqueous dispersion of crosslinkable (e.g. phosphorylated)MFC is applied between two substrates and subsequently dried, it can deliver strong adhesiveproperties (strong bonding), providing that the drying occurs at a high enough temperatureto trigger crosslinking, i.e. above 60 °C. Moreover, since crosslinkable MFC can crosslink withpaper-based substrates and the like, it is expected that these types of adhesive exhibit highperformance even under moist conditions. Such properties are not achieved with conventional waterborne adhesives based on natural sources.
    Thus, a good adhesion with good wet performances is achieved by adding a dispersioncomprising phosphorylated MFC as an adhesive and triggering the adhesion by heating. The dispersion may also comprise other components to further improve the adhesion, e.g. starch.
    So, in a first aspect the present invention relates to a waterborne adhesive comprisingcrosslinkable microfibrillated cellulose (MFC) dispersed in an aqueous solvent. Preferably, the waterborne adhesive does not comprise additional crosslinking agents.
    In a second aspect, the present invention relates to method for adhering a first and a second surface together, said method comprising the steps of: a. applying a waterborne adhesive as defined herein, to at least one of said first OI' SECOFIÖ SUFfÖCES; b. placing said first and second surfaces in contact with each other, such that the waterborne adhesive is located between said surfaces; c. treating said waterborne adhesive so as to provide crosslinking of the crosslinkable MFC, thereby adhering said first and second surfaces together.
    In a third aspect, the use of an aqueous dispersion of crosslinkable microfibrillated cellulose(MFC) as a waterborne adhesive is provided. Further aspects of the invention are provided in the following text and in the dependent claims.
    DETAILED DISCLOSURE In a first aspect, a waterborne adhesive is provided, which comprises crosslinkable microfibrillated cellulose (MFC) dispersed in an aqueous solvent.
    Microfibrillated cellulose (MFC) or so called cellulose microfibrils (CMF) shall in the context ofthe present application mean a nano-scale cellulose particle fiber or fibril with at least onedimension less than 100 nm. MFC comprises partly or totally fibrillated cellulose orlignocellulose fibers. The cellulose fiber is preferably fibrillated to such an extent that the finalspecific surface area of the formed MFC is from about 1 to about 300 mZ/g, such as from 1 to200 mZ/g or more preferably 50-200 mZ/g when determined for a freeze-dried material withthe BET method.
    Various methods exist to make MFC, such as single or multiple pass refining, pre-hydrolysisfollowed by refining or high shear disintegration or liberation of fibrils. One or several pre-treatment steps are usually required in order to make MFC manufacturing both energy-efficient and sustainable. The cellulose fibers of the pulp to be supplied may thus be pre-treated enzymatically or chemically, for example to reduce the quantity of hemicellulose orlignin. The cellulose fibers may be chemically modified before fibrillation, wherein thecellulose molecules contain functional groups other (or more) than found in the originalcellulose. Such groups include, among others, carboxymethyl, aldehyde and/or carboxylgroups (cellulose obtained by N-oxyl mediated oxidation, for example "TEMPO"), orquaternary ammonium (cationic cellulose). After being modified or oxidized in one of the above-described methods, it is easier to disintegrate the fibers into MFC or NFC.
    The nanofibrillar cellulose may contain some hemicelluloses; the amount is dependent on theplant source. Mechanical disintegration of the pre-treated fibers, e.g. hydrolysed, pre-swelled, or oxidized cellulose raw material is carried out with suitable equipment such as arefiner, grinder, homogenizer, colloider, friction grinder, ultrasound sonicator, single - ortwin-screw extruder, fluidizer such as microfluidizer, macrofluidizer or fluidizer-typehomogenizer. Depending on the MFC manufacturing method, the product might also containfines, or nanocrystalline cellulose or e.g. other chemicals present in Wood fibers or inpapermaking process. The product might also contain various amounts of micron size fiber particles that have not been efficiently fibrillated.
    MFC can be produced from wood cellulose fibers, both from hardwood or softwood fibers. Itcan also be made from microbial sources, agricultural fibers such as wheat straw pulp,bamboo, bagasse, or other non-wood fiber sources. It is preferably made from pulp includingpulp from virgin fiber, e.g. mechanical, chemical and/or thermomechanical pulps. It can also be made from broke or recycled paper.
    The above described definition of MFC includes, but is not limited to, the proposed TAPPIstandard W13021 on cellulose nano or microfibril (CMF) defining a cellulose nanofibermaterial containing multiple elementary fibrils with both crystalline and amorphous regions, having a high aspect ratio with width of 5-30 nm and aspect ratio usually greater than 50.
    Chemically-modified MFC comprising crosslinkable groups is “crosslinkable MFC”.Crosslinkable MFC forms bonds between the MFC fibrils upon crosslinking, e.g. by heat-treatment or pH treatment. Particular crosslinkable MFCs may be phosphorylatedmicrofibrillated cellulose (P-MFC) or dialdehyde microfibrillated cellulose (DA-MFC); ormixtures thereof, preferably P-MFC.
    Phosphorylated microfibrillated cellulose (P-MFC) is typically obtained by reacting cellulosepulp fibers with a phosphorylating agent such as phosphoric acid, and subsequentlyfibrillating the fibers to P-MFC. One particular method involves providing a suspension ofcellulose pulp fibers in Water, and phosphorylating the cellulose pulp fibers in said Watersuspension With a phosphorylating agent, followed by fibrillation with methods common inthe art. Suitable phosphorylating agents include phosphoric acid, phosphorus pentaoxide,phosphorus oxychloride, diammonium hydrogen phosphate and sodium dihydrogen phosphate.
    In the reaction to form P-MFC, alcohol functionalities (-OH) in the cellulose are converted tophosphate groups (-OPO32'). In this manner, crosslinkable functional groups (phosphate groups) are introduced to the pulp fibers or microfibrillated cellulose.
    Typically, the P-MFC is in the form of its sodium salt.
    Dialdehyde microfibrillated cellulose (DA-MFC) is typically obtained by reacting cellulose withan oxidising agent such as sodium periodate. During the periodate oxidation, selectivecleavage of the C2-C3 bond of the anhydroglucose (AGU) unit of cellulose takes place, withconcurrent oxidation of the C2- and C3-OH moieties to aldehyde moieties. In this manner, crosslinkable functional groups (aldehyde groups) are introduced to the cellulose.
    The aqueous solvent used in the waterborne adhesive may consist solely of water, withoutadditives. However, the aqueous solvent may include additives common in the field ofadhesives, such as starch, which can improve the adhesion. To improve miscibility/solubility,the aqueous solvent may include non-aqueous, water-miscible solvents such as alcohols, but this is less desirable from an environmental point of view.
    The waterborne adhesive suitably comprises more than 25%, preferably more than 50%, such as e.g. more than 75% by dry weight crosslinkable MFC on a dry basis.
    The waterborne adhesive may comprise additional components, such as other MFC gradesand/or inorganic fillers. Of these, non-modified MFC is preferred, as good crosslinking withcrosslinkable MFC can be obtained.
    Crosslinkable MFC can form crosslinks (and thereby good adhesion) itself, without additionalcrosslinking agents. Therefore, in one preferred embodiment, the waterborne adhesive does not comprise additional crosslinking agents.
    In a second aspect, a method is provided for adhering a first and a second surface together.
    The method comprises the general steps of: a. applying a waterborne adhesive as defined herein, to at least one of said first OI' SECOFIÖ SUFfÖCES; b. placing said first and second surfaces in contact with each other, such that the waterborne adhesive is located between said surfaces; c. treating said waterborne adhesive so as to provide crosslinking of the MFC, thereby adhering said first and second surfaces together.
    When the crosslinkable MFC is phosphorylated microfibrillated cellulose (P-MFC), thetreatment in step c is heat treatment, suitably at a temperature of between 60 and 200 °C,preferably between 70 and 120 °C. When the crosslinkable MFC is dialdehyde microfibrillatedcellulose (DA-MFC), the treatment in step c is reducing the pH, suitably to pH 7 or below,such as to pH 6 or below, or pH 5 or below.
    The treatment in step c. may take place for a time of between 10 and 180 minutes.
    Due to the cellulosic nature of the crosslinkable MFC, and the nature of the crosslinking, good adhesion of cellulose based materials such as e.g. paper, cardboard or wood can take place.
    It is therefore preferred that said first and/or said second surfaces comprise or consist of cellulose-based materials such as e.g. paper, cardboard or wood.
    All details of the Waterborne adhesive relating to the first aspect of the invention are alsorelevant to the second aspect of the invention. In particular, it is preferred that the Waterborne adhesive used in step a. does not comprise additional crosslinking agents.
    In a third aspect, the use of an aqueous dispersion of crosslinkable microfibrillated cellulose(MFC) as a Waterborne adhesive is also provided. All details of the crosslinkablemicrofibrillated cellulose and the aqueous dispersion are as provided above are also relevant for this aspect of the invention.
    Although the invention has been described with reference to a number of aspects andembodiments, these aspects and embodiments may be combined by the person skilled in the art, while remaining within the scope of the present invention.
    权利要求:
    Claims (14)
    [1] 1. A waterborne adhesive comprising crosslinkable microfibrillated cellulose (MFC) dispersed in an aqueous solvent.
    [2] 2. The waterborne adhesive according to claim 1, wherein the crosslinkable MFC isphosphorylated microfibrillated cellulose (P-MFC) or dialdehyde microfibrillated cellulose (DA-MFC), or mixtures thereof; preferably P-MFC.
    [3] 3. The waterborne adhesive according to any one of the preceding claims, wherein thecrosslinkable MFC is phosphorylated microfibrillated cellulose (P-MFC), in the form of its sodium salt.
    [4] 4. The waterborne adhesive according to any one of the preceding claims, comprisingmore than 25%, preferably more than 50%, such as e.g. more than 75% by dry weightcrosslinkable MFC.
    [5] 5. The waterborne adhesive according to any one of the preceding claims, comprising additional components, such as other MFC grades and/or inorganic fi|ers.
    [6] 6. The waterborne adhesive according to any one of the preceding claims, further comprising starch.
    [7] 7. The waterborne adhesive according to any one of the preceding claims, wherein the waterborne adhesive does not comprise additional crosslinking agents.
    [8] 8. A method for adhering a first and a second surface together, said method comprising the steps of: a. applying a waterborne adhesive as defined in any one of the preceding claims, to at least one of said first or second surfaces; b. placing said first and second surfaces in contact with each other, such that the waterborne adhesive is located between said surfaces; c. treating said waterborne adhesive so as to provide crosslinking of the crosslinkable MFC, thereby adhering said first and second surfaces together.
    [9] 9. The method according to claim 8, wherein said crosslinkable MFC is phosphorylatedmicrofibrillated cellulose (P-MFC), and wherein said treatment in step c is heat treatment, suitably at a temperature of between 60 and 200 °C, preferably between 70 and 120 °C.
    [10] 10. The method according to claim 8, wherein said crosslinkable MFC is dialdehydemicrofibrillated cellulose (DA-MFC), and wherein said treatment in step c is reducing the pH, suitably to pH 7 or below.
    [11] 11. The method according to any one of c|aims 8-10, wherein said treatment takes place for a time of between 10 and 180 minutes.
    [12] 12. The method according to any one of c|aims 8-11, wherein said first and/or said secondsurfaces comprise or consist of cellulose-based materials such as e.g. paper, cardboard or wood.
    [13] 13. The method according to any one of c|aims 8-11, wherein the waterborne adhesive used in step a. does not comprise additional crosslinking agents
    [14] 14. Use of an aqueous dispersion of crosslinkable microfibrillated cellulose (MFC) according to any one of c|aims 1-7 as a waterborne adhesive.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    KR20120091162A|2009-11-06|2012-08-17|스토라 엔소 오와이제이|Process for the production of a paper or board product and a paper or board produced according to the process|
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    US10875284B2|2015-09-10|2020-12-29|University Of Maine System Board Of Trustees|Composite products of paper and cellulose nanofibrils and process of making|
    US10662585B2|2016-03-31|2020-05-26|Oji Holdings Corporation|Method for producing fibrous cellulose, and fibrous cellulose|
    FR3052101B1|2016-06-01|2019-05-10|Centre Technique De L'industrie Des Papiers, Cartons Et Celluloses|FIXING METHOD AND SYSTEM OBTAINED BY SUCH A METHOD|
    WO2018012643A1|2016-07-15|2018-01-18|スターライト工業株式会社|Resin composition and method for producing same|SE543403C2|2019-05-02|2021-01-05|Stora Enso Oyj|Method for manufacturing laminated veneer lumer product|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1850727A|SE543251C2|2018-06-13|2018-06-13|Waterborne adhesive comprising crosslinkable microfibrillated cellulose|SE1850727A| SE543251C2|2018-06-13|2018-06-13|Waterborne adhesive comprising crosslinkable microfibrillated cellulose|
    PCT/IB2019/054840| WO2019239299A1|2018-06-13|2019-06-11|Waterborne adhesive comprising crosslinkable microfibrillated cellulose|
    JP2020568959A| JP2021527153A|2018-06-13|2019-06-11|Aqueous adhesive containing crosslinkable microfibrillated cellulose|
    EP19819018.3A| EP3807373A1|2018-06-13|2019-06-11|Waterborne adhesive comprising crosslinkable microfibrillated cellulose|
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