An adhesive

Abstract

Disclosed is an adhesive, wherein the adhesive comprises a lignin-based binder composition, wherein: - the lignin-based binder composition is prepared from crosslinking agent polymerized with polymerizable substance in the presence of triacetin, - at least 30 weight-% of the polymerizable substance originates from lignin, and - triacetin is used in an amount of 0.1 - 5 weight-% based on the total wet weight of the lignin-based binder composition. Further is disclosed the use of the adhesive and of triacetin. Further is disclosed an insulating wool product.

Description

[0001] AN ADHESIVE

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to an adhesive . Further, the present disclosure relates to the use of the adhesive and to the use of triacetin . Further, the present disclosure relates to an insulating wool product .

[0004] BACKGROUND

[0005] An insulating wool product can be produced by spaying a binder on a melted fiber matrix . Traditionally used binders for insulating wool production are sodium silicates , polyesters , melamine urea formaldehyde , polyamides , furane-based resins , and other phenolic resin ( PF) -based binders . PF-resin has a high free formaldehyde ( FA) content affecting the emissions of the final product unless a relevant amount of urea is used . The inventors have therefore recogni zed the need to produce an adhesive to be used for producing an insulating wool product in a more sustainable manner .

[0006] SUMMARY

[0007] Disclosed is an adhesive , wherein the adhesive comprises a lignin-based binder composition, wherein : the lignin-based binder composition is prepared from crosslinking agent polymeri zed with polymeri zable substance in the presence of triacetin,

[0008] - at least 30 weight-% of the polymeri zable substance originates from lignin, and

[0009] - triacetin is used in an amount of 0 . 1 - 5 weight-% based on the total wet weight of the ligninbased binder composition . Further is disclosed the use of the adhesive as disclosed in the current specification for producing an insulating wool product , a wood-based panel , a composite , a coating, a paint , a laminate , a film, a filter material , an abrasive , a foundry mold, or an insulating foam .

[0010] Further is disclosed the use of triacetin in an adhesive comprising a lignin-based binder composition for producing an insulating wool product , a wood-based panel , a composite , a coating, a paint , a laminate , a film, a filter material , an abrasive , a foundry mold, or an insulating foam, wherein the lignin-based binder composition is prepared from crosslinking agent polymeri zed with polymeri zable substance in the presence of triacetin, wherein at least 30 weight-% of the polymerizable substance originates from lignin, and the triacetin is used in the adhesive in an amount of 0 . 1 - 5 weight-% based on the total wet weight of the ligninbased binder composition .

[0011] Further is disclosed the use of triacetin in the production of an adhesive comprising a lignin-based binder composition for increasing the strength of an insulating wool product produced with the adhesive , wherein the lignin-based binder composition is prepared from crosslinking agent polymeri zed with polymeri zable substance in the presence of triacetin, wherein at least 30 weight-% of the polymeri zable substance originates from lignin , and the triacetin i s used in the adhes ive in an amount of 0 . 1 - 5 weight-% based on the total wet weight of the lignin-based binder composition .

[0012] Further is disclosed an insulating wool product comprising a f iber matrix and an adhesive , wherein the adhesive comprises a lignin-based binder composition, wherein : the lignin-based binder composition is prepared from crosslinking agent polymeri zed with polymeri zable substance in the presence of triacetin, - at least 30 weight-% of the polymeri zable substance originates from lignin, and

[0013] - triacetin is used in an amount of 0 . 1 - 5 weight-% based on the total wet weight of the ligninbased binder composition .

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawing, which is included to provide a further understanding of the embodiments and constitute a part of this specification, illustrates some embodiments . In the drawing :

[0016] Fig . 1 presents the results from example 2 .

[0017] DETAILED DESCRIPTION

[0018] The present disclosure relates to an adhesive , wherein the adhesive comprises a lignin-based binder composition, wherein : the lignin-based binder composition is prepared from crosslinking agent polymeri zed with polymeri zable substance in the presence of triacetin,

[0019] - at least 30 weight-% of the polymeri zable substance originates from lignin, and

[0020] - triacetin is used in an amount of 0 . 1 - 5 weight-% based on the total wet weight of the ligninbased binder composition .

[0021] In one embodiment , the adhesive is an adhesive for insulating wool products .

[0022] The present disclosure further relates to the use of the adhesive as disclosed in the current specification for producing an insulating wool product , a wood-based panel , a composite , a coating, a paint , a laminate , a film, a filter material , an abrasive , a foundry mold, or an insulating foam .

[0023] The present disclosure further relates to the use of triacetin in an adhesive comprising a ligninbased binder composition for producing an insulating wool product , a wood-based panel , a composite , a coating, a paint , a laminate , a film, a filter material , an abrasive , a foundry mold, or an insulating foam, wherein the lignin-based binder composition is prepared from crosslinking agent polymeri zed with polymeri zable substance in the presence of triacetin, wherein at least 30 weight-% of the polymeri zable substance originates from lignin , and the triacetin i s used in the adhes ive in an amount of 0 . 1 - 5 weight-% based on the total wet weight of the lignin-based binder composition .

[0024] The present disclosure further relates to the use of triacetin in the production of an adhesive comprising a lignin-based binder composition for increasing the strength of an insulating wool product produced with the adhesive , wherein the lignin-based binder composition is prepared from crosslinking agent polymeri zed with polymeri zable substance in the presence of triacetin, wherein at least 30 weight-% of the polymerizable substance originates from lignin, and the triacetin is used in the adhesive in an amount of 0 . 1 - 5 weight-% based on the total wet weight of the ligninbased binder composition .

[0025] The wet strength and the dry strength of a product , such as an insulating wool product , may be determined by a so-called sandbar method . The sandbar method may be carried out as follows : The adhesive is diluted with water to 30 weight-% dry matter content ( DMC) and mixed with silica sand . The mixture of the adhesive and silica sand is cured in oven, at a temperature of 180 ° C for 2 hour and 45 minutes , after which the dry strength of the formed sandbars is tested with a 3-point bending system according to standard EN 310 : 1993 (Modulus of rupture ) . The wet strength is determined by soaking the formed sandbars in a water solution for 24 hours at room temperature while maintaining the water level constant . After this the surface water is removed from the sandbars by holding the sandbars in a rack with a 45-degree angle for 1010 . 5 minutes . After these procedures the wet strength is tested with a 3-point bending device according to standard EN 310 : 1993 (Modulus of rupture ) .

[0026] Triacetin may be used to increase the strength of different products or applications . Triacetin may be used to increase the strength of an insulating wool product . In one embodiment , triacetin is used to increase the wet strength and / or the dry strength of an insulating wool product . In one embodiment , triacetin is used to increase the wet strength or the dry strength of an insulating wool product . In one embodiment , triacetin i s used to increase the wet strength and the dry strength of an insulating wool product . In one embodiment , triacetin is used to increase the wet strength of an insulating wool product . In one embodiment , triacetin is used to increase the dry strength of an insulating wool product .

[0027] The present disclosure further relates to an insulating wool product comprising a fiber matrix and an adhesive , wherein the adhesive comprises a ligninbased binder composition, wherein : the lignin-based binder composition is prepared from crosslinking agent polymeri zed with polymeri zable substance in the presence of triacetin,

[0028] - at least 30 weight-% of the polymeri zable substance originates from lignin, and

[0029] - triacetin is used in an amount of 0 . 1 - 5 weight-% based on the total wet weight of the ligninbased binder composition .

[0030] In the current specification the amounts of different components / elements in the adhesive are presented in weight-% based on either the total wet weight of the adhesive or the binder composition or the total dry weight of the adhesive or the binder composition . The "total wet weight" should in this specification be understood, unless otherwise stated, as the weight of both the dry matter and the liquid part, e.g. water, of the adhesive or the binder composition .

[0031] The "total dry weight" should in this specification should in this specification be understood, unless otherwise stated, as the weight of the dry matter of the adhesive or the binder composition, i.e. excluding water.

[0032] As is clear to the skilled person, the total amount of the different components / elements in the adhesive may not exceed 100 weight-%. The amount in weight-% of the different components / elements in the adhesive may vary within the given ranges.

[0033] The inventors surprisingly found out that by using the adhesive as disclosed in the current specification, one is able to produce a product, such as an insulating wool product that exhibits a high amount of bio-based components while simultaneously having a high strength. Thus, the adhesive as disclosed in the current specification has the added utility of being a more environmentally friendly solution to be used for producing e.g. an insulating wool product that exhibits properties needed for further applications.

[0034] In one embodiment, the adhesive comprises the lignin-based binder composition in an amount of 65 - 99.9 weight-%, or 69 - 99 weight-%, or 75 - 98 weight- % , based on the total dry weight of the adhesive. In one embodiment, the adhesive comprises the lignin-based binder composition in an amount of 80 - 99.9 weight-%, or 90 - 99 weight-%, or 93 - 97 weight-%, based on the total dry weight of the adhesive.

[0035] In one embodiment, 30 - 100 weight-%, or 40 - 99 weight-%, or 50 - 95 weight-%, or 60 - 90 weight-%, or 70 - 85 weight-%, of the polymerizable substance originates from lignin. In the context of this specification, the term "lignin" may refer to lignin originating from any suitable lignin source . In one embodiment , the lignin is essentially pure lignin . By the expression "essentially pure lignin" should be understood as at least 70 % pure lignin, or at least 90 % pure lignin, or at least 95 % pure lignin, or at least 98 % pure lignin . The essentially pure lignin may comprise at most 30 % , or at most 10 % , or at most 5 % , or at most 2 % , of other components and / or impurities . Extractives and carbohydrates such as hemicelluloses can be mentioned as examples of such other components .

[0036] The lignin used may be selected from a group consisting of kraft lignin, steam explosion lignin, biorefinery lignin, supercritical separation lignin, hydrolysis lignin, flash precipitated lignin, biomass originating lignin, lignin from alkaline pulping process , lignin from soda process , lignin from organosolv pulping, lignin from alkali process , lignin from enzymatic hydrolysis process , and any combination thereof . In one embodiment , the lignin originates from biomass . In one embodiment , the lignin is wood based lignin . The lignin can originate from softwood, hardwood, annual plants or from any combination thereof .

[0037] By "kraft lignin" is to be understood in this specification, unless otherwise stated, lignin that originates from kraft black l iquor . Black liquor is an alkaline aqueous solution of lignin residues , hemi cellulose , and inorganic chemicals used in a kraft pulping process . The black liquor from the pulping process comprises components originating from different softwood and hardwood species in various proportions . Lignin can be separated from the black liquor by different , techniques including e . g. precipitation and filtration . Lignin usually begins precipitating at pH values below 11 - 12 . Different pH values can be used in order to precipitate lignin fractions with different properties . These lignin fractions differ from each other by molecular weight distribution, e . g. Mw and Mn, polydispersity, hemicellulose and extractive contents . The molar mass of lignin precipitated at a higher pH value is higher than the molar mass of lignin precipitated at a lower pH value . Further, the molecular weight distribution of lignin fraction precipitated at a lower pH value is wider than of lignin fraction precipitated at a higher pH value . The precipitated lignin can be purified from inorganic impurities , hemicellulose and wood extractives using acidic washing steps . Further purification can be achieved by filtration .

[0038] The term "flash precipitated lignin" should be understood in this specification as lignin that has been precipitated from black liquor in a continuous process by decreasing the pH of a black liquor flow, under the influence of an over pressure of 200 - 1000 kPa, down to the precipitation level of lignin using a carbon dioxide based acidifying agent , preferably carbon dioxide , and by suddenly releasing the pressure for precipitating lignin . The method for producing flash precipitated lignin is disclosed in patent application FI 20106073 . The res idence time in the above method is under 300 s . The flash precipitated lignin particles , having a particle diameter of les s than 2 pm, form agglomerates , which can be separated from black liquor using e . g. filtration . The advantage of the flash precipitated lignin is its higher reactivity compared to normal kraft lignin . The flash precipitated lignin can be purified and / or activated if needed for the further processing .

[0039] The lignin may be derived from an alkali process . The alkali process can begin with liquidi zing biomass with strong alkali followed by a neutralization process . After the alkali treatment , the l ignin can be precipitated in a similar manner as presented above . The lignin may be derived from steam explosion . Steam explosion is a pulping and extraction technique that can be applied to wood and other fibrous organic material .

[0040] By "biorefinery lignin" is to be understood in this specification, unless otherwise stated, lignin that can be recovered from a refining facility or process where biomass is converted into fuel , chemicals and other materials .

[0041] By "supercritical separation lignin" is to be understood in this specification, unless otherwise stated, lignin that can be recovered from biomass using supercritical fluid separation or extraction technique . Supercritical conditions correspond to the temperature and pressure above the critical point for a given substance . In supercritical conditions , distinct liquid and gas phases do not exist . Supercritical water or liquid extraction is a method of decomposing and converting biomass into cellulosic sugar by employing water or liquid under supercritical conditions . The water or liquid, acting as a solvent , extracts sugars from cellulose plant matter and lignin remains as a solid particle .

[0042] The lignin may be derived from a hydrolysis process . The lignin derived from the hydrolysis process can be recovered from paper-pulp or wood-chemical processes .

[0043] The lignin may originate from an organosolv process . Organosolv is a pulping technique that uses an organic solvent to solubili ze lignin and hemicellulose .

[0044] The lignin used for producing the lignin-based binder composition may be crushed or uncrushed lignin . The lignin may be in the form of lignin agglomerates .

[0045] The lignin-based binder composition may have a pH value of 9 - 11 , or 9 . 3 - 10 . 5 , or 9 . 5 - 10 . The above pH values have the added utility of stabili zing the binder composition such that lignin may not be precipitated therefrom.

[0046] Polymerizing the crosslinking agent and the polymerizable substance may take place in an aqueous composition in the presence of triacetin, and conducted under heating at a temperature of 50 - 95 °C, or 60 - 93 °C, or 75 - 90 °C, or 70 - 80 °C, or 70 - 90 °C. The heating may be continued until a binder composition with a desired viscosity value is formed. The polymerization may be continued for 0.15 - 6 hours, or 0.25 - 5 hours, or 0.5 - 3.5 hours. In one embodiment, the lignin-based binder composition has a viscosity of 10 - 300 mPa -s, 50 - 275 mPa -s, or 100 - 250 mPa -s, or 125 - 225 mPa-s. The viscosity can be measured at a temperature of 25 °C by using a rotary viscometer (Digital Brookfield viscometer LVDV-II+ Pro; cone spindle) . The viscosity of the binder composition can be adjusted by the use of the urea and / or water.

[0047] The crosslinking agent may be an aldehyde, such as formaldehyde or paraformaldehyde. In one embodiment, the aldehyde is prepared from bio-methanol. The aldehyde may thus be of biobased origin. The aldehyde may alternatively be of fossil origin. In one embodiment, the aldehyde is prepared from methanol.

[0048] The total amount of crosslinking agent used for producing the binder composition may be 15 - 35 weight- % , or 17 - 30 weight-%, or 20 - 27 weight-%, based on the total dry weight of the binder composition. The total amount of polymerizable substance used for producing the binder composition may be 40 - 70 weight- % , or 45 - 67 weight-%, or 47 - 65 weight-%, or 50 - 63 weight-%, based on the total dry weight of the binder composition. The weight ratio of the crosslinking agent to the polymerizable substance may be 0.15 - 0.55, or 0.20 - 0.40.

[0049] A catalyst may also be used in the aqueous composition. The catalyst may comprise a salt or a hydroxide of an alkali metal or alkali earth metal. The catalyst may be selected from a group consisting of sodium hydroxide, potassium hydroxide, barium hydroxide, and any combination or mixture thereof. In one embodiment, the catalyst is sodium hydroxide.

[0050] The polymerizing agent may in addition to lignin comprise a compound selected from the class of phenols. In this specification, unless otherwise stated, the term "compound selected from the class of phenols" should be understood as meaning a fossil-based compound of phenols. I.e. phenols are compounds consisting of a single aromatic ring where to one or more hydroxyls (— OH) are bonded. Such a compound selected from the class of phenols may be e.g. phenol, cresol, or resorcinol. Such phenols are toxic compounds. In one embodiment, no compound selected from the class of phenols is used for producing the binder composition. The adhesive as disclosed in the current specification has the added utility of possibly being free of materials of fossil origin. The lignin-based binder composition, and thus the adhesive, produced may thus be free of fossil-based phenol compound(s) . The lignin-based binder composition may thus be prepared as a non-toxic lignin-based binder composition. I.e. a lignin-based binder composition with reduced share of toxic or hazardous compounds may be prepared. The lignin-based binder composition may be prepared as a binder composition having 100 % biological origin. Thus, all the components used for preparing the lignin-based binder composition may be of biological origin and thus no fossil-based components may need to be used.

[0051] In one embodiment, the triacetin is used in an amount of 0.2 - 4 weight-%, or 0.4 - 3 weight-%, or 0.6 - 2.5 weight-%, or 0.8 - 2 weight-%, or 1.0 - 1.5 weight- % , based on the total wet weight of the lignin-based binder composition. Traditionally, an insulation material produced from a lignin-based binder composition in an insulating wool process has tended to have poor dry strength properties. The strength has decreased further when the amount of substituted fossil phenol replaced with renewable lignin is increased. The inventors surprisingly found out that the use of triacetin in the adhesive used for producing e.g. the insulating wool product, increases the dry strength to the same level as when using commercial phenol- f ormaldehyde-resins . The dry strength of the insulating wool product may be increased when using triacetin in the adhesive, which is based on the use of a ligninbased binder composition. The use of triacetin has the added utility of enabling a deeper penetration of the adhesive into the fiber matrix, which then improve the strength of the insulating wool product. Further, the use of triacetin has the added utility of increasing the reactivity of lignin, which further affects the strength .

[0052] In one embodiment, the adhesive is prepared by combining the lignin-based binder composition with at least one of silane, ammonium sulphate, and urea. In one embodiment, the adhesive is prepared by combining the lignin-based binder composition with at least one of silane, ammonium sulphate, urea, and triacetin. In one embodiment, the prepared lignin-based binder composition is combined with triacetin.

[0053] In one embodiment, the adhesive further comprises silane in an amount of 0.1 - 0.9 weight-%, or 0.2 - 0.7 weight-%, or 0.3 - 0.5 weight-%, based on the total dry weight of the adhesive. Silane (3- (triethoxysilyl) -propylamine) , when used in the adhesive for producing e.g. an insulating wool product, has the added utility of promoting adhesion to achieve high strength and good moisture resistance in an insulating wool product. In one embodiment, the adhesive comprises no silane. In one embodiment, the adhesive further comprises ammonium sulphate in an amount of 0.5 - 15 weight-%, or 1 - 14 weight-%, or 2 - 13 weight-%, or 3

[0054] - 12 weight-%, or 4 - 11 weight-%, or 5 - 10 weight-%, or 6 - 9 weight-%, based on the total dry weight of the adhesive. Ammonium sulphate, when used in the adhesive for producing e.g. an insulating wool product, has the added utility of providing the insulating wool product a satisfactory tensile strength formed during the curing process. In one embodiment, no ammonium sulphate is used in the adhesive. In one embodiment, the adhesive comprises no ammonium sulphate.

[0055] In one embodiment, the adhesive further comprises urea in an amount of 0.1 - 20 weight-%, or 0.2

[0056] - 16 weight-%, or 0.3 - 13 weight-%, or 0.5 - 9 weight- % , or 0.7 - 8 weight-%, or 1 - 7 weight-%, or 2 - 6 weight-%, or 3 - 5 weight-%, based on the total wet weight of the binder composition. The urea may be used for producing an adhesive with a suitably low viscosity value. The urea may further be used for increasing the dry solids content of the adhesive. Urea may be used to decrease the viscosity of the adhesive so that it may be sprayed on the fiber matrix when used for producing an insulating wool product. In one embodiment, no urea is used in the adhesive. In one embodiment, the adhesive comprises no urea.

[0057] In one embodiment, the adhesive comprises water .

[0058] In one embodiment, the lignin-based binder composition has a viscosity of 10 - 300 mPa -s, 50 - 275 mPa -s, or 100 - 250 mPa -s, or 125 - 225 mPa-s.

[0059] The adhesive as disclosed in the current specification may be used for producing an insulating wool product. The insulating wool product may comprise a fiber matrix and an adhesive as disclosed in the current specification. In one embodiment, the adhesive is used for producing an insulating wool product, wherein the insulating wool product comprises a fiber matrix selected from glass fiber, stone fiber, or slag fiber. In one embodiment, the insulating wool product comprises a fiber matrix selected from glass fiber, stone fiber, or slag fiber. The fiber matrix may be glass fiber, stone fiber, or slag fiber, or any combination of these. In one embodiment, the insulating wool product is a mineral wool product. In one embodiment, the mineral wool product is a glass wool product, a stone wool product, or a slag wool product.

[0060] The adhesive as disclosed in the current specification may be used for producing wood-based panels. Plywood, oriented strand board (OSB) , medium density fiber board (MDF) , high density fiber board (HDF) , low density fiber board (LDF) , and laminated veneer lumber (LVL) may be mentioned as examples of wood-based panels. The adhesive as disclosed in the current specification may be used for producing laminates. High pressure laminates (HPL) and continuous pressure laminates (CPL) may be mentioned as examples of laminates.

[0061] The adhesive as disclosed in the current specification may be used for producing films, such as surface films, or filters, such as impregnated filters.

[0062] In one embodiment, the total amount of adhesive in the insulating wool product is 1 - 10 weight-%, or 2 - 9 weight-%, or 3 - 8 weight-%, or 4 - 7 weight-%, or 5 - 6 weight-%, based on the total weight of the insulating wool product.

[0063] Further additive (s) may be combined with the adhesive for producing the insulating wool product. Dedusting oils, emulsifiers, dyes, extenders, and scavengers may be mentioned as examples of such additives .

[0064] The insulating wool product may be produced by spraying the adhesive over melted fiber matrix, which is pre-formed in high temperatures, e.g. at over 1000 °C . The fiber matrix of the insulating wool product may be in the form of a sheet , slabs , batts , rolls , a panel , or blown .

[0065] In one embodiment , the dry strength is increased by at least 10 % , or at least 13 % , or at least 20 % , or at least 30 % , or at least 50 % , as determined based on the sandbar method as disclosed in the description, when using triacetin in the ligninbased binder composition compared to using an adhesive prepared in an otherwise equal manner but without using triacetin in the lignin-based binder composition .

[0066] In one embodiment , the wet strength of the insulating wool product is increased by at least 10 % , or at least 13 % , or at least 20 % , or at least 30 % , or at least 50 % , as determined based on the sandbar method as disclosed in the description, when using triacetin in the lignin-based binder composition compared to using an adhesive prepared in an otherwise equal manner but without using triacetin in the ligninbased binder composition .

[0067] Traditionally adhesives used in insulating wool products are based on sodium silicates , polyesters , melamine urea formaldehyde , polyamides , furane-based resins , and others , phenolic resin ( PF) -based binders . Even though the high fossil carbon containing PF-binder compositions can be replaced with lower carbon footprint lignin-based compositions in adhesives for insulating wool products , these suffer from low dry strength properties , especially when the amount of lignin in the binder composition is increased . The inventors surprisingly found out that the use of triacetin in adhesives formed from lignin-based binder compositions has the added utility of improving the strength properties of the insulating wool product formed with the adhesive .

[0068] The adhesive as disclosed in the current speci fication has the added util ity of enabling one to provide an adhesive having properties being beneficial for producing an insulating wool product . The produced binder composition may exhibit a high content of biobased materials as a lignin-based binder composition is used as a basi s for the adhes ive . The amount of l ignin used in the adhesive may be increased thus reducing the use of fossil-based compounds . Using the adhesive as disclosed in the current specification for the production of an insulating wool product has the added utility of providing the wool product with low emissions while simultaneously exhibiting a high strength .

[0069] EXAMPLES

[0070] Reference will now be made in detail to the embodiments of the present disclosure , examples of which are illustrated in the accompanying drawings .

[0071] The description below discloses some embodiments in such a detail that a person skilled in the art is able to utili ze the adhesive based on the disclosure . Not all steps of the embodiments are discussed in detail , as many of the steps will be obvious for the person skilled in the art based on thi s disclosure .

[0072] Example 1 - Producing adhes ives for an insulating wool product

[0073] In this example , different adhes ives were prepared . The following components and their percentages were used in this example for firstly producing ligninbased binder composition samples :

[0074] Binder composition with 70 weight-% of the polymeri zable substance being lignin (LPF700 )

[0075] Kraft lignin 20 weight-%

[0076] Phenol 8 . 5 weight-%

[0077] Formaldehyde 9 weight-%

[0078] NaOH 4 weight-% Triacetin 0, 0.5, 1, or 1.5 weight-%

[0079] The rest being water

[0080] The above components were mixed and heated at a temperature of about 70 °C in order to polymerize the lignin, phenol, and formaldehyde, in the presence of triacetin, to form the lignin-based binder compositions. Further samples were prepared by adding varying amounts of silane (3- (triethoxysilyl) -propylamine) , ammonium sulphate and / or urea with the prepared lignin-based binder composition. The amounts of triacetin, silane, ammonium sulphate, and urea used in the different samples are indicated in the blow tables. A commercial phenol-f ormaldehyde resin (PF) was used as a comparative example. The prepared adhesives were tested as presented in the below. The different adhesives prepared are presented in below tables la, lb, and 1c.

[0081] Table la. Prepared samples

[0082] Table lb. Prepared samples

[0083] Table 1c . Prepared samples

[0084] Example 2 - Testing the strength properties Prepared adhesive samples were used to prepare sandbars and the sandbar samples were tested as described below . The sandbars were prepared by mixing the adhesive samples (diluted with water to a dry matter content of 30 weight-% ) with silica sand (grain si ze of 0 . 1 - 0 . 6 mm) in a mold with dimensions of 173 mm in length, 22 mm in width and 22 mm in height , and then by pressing the formed mixture with a suitable hydraulic press capable of producing 1 . 6 N / mm2of specific pressure . The pressed sandbar mixture was then cured in an oven at a temperature of 180 ° C for 2 hour and 45 minutes .

[0085] The formed sandbars where then analyzed for the dry strength and wet strength of the formed sandbar samples . The dry strength of the sandbar samples was tested according to standard EN 310 : 1993 Modulus of rupture (which is equal to the dry strength of the sample ) . The wet strength ( standard EN 310 : 1993 modulus of rupture , named strength after absorption in the figures ) was analyzed after the sandbar samples had been soaked in room temperature water for 24 hours and after holding the sandbars in a rack with a 45-degree angle for 10±0 . 5 minutes to remove surface water .

[0086] The results are presented in Fig . 1 . From the results one can see that samples with as low amount as 0 . 5 weight-% of triacetin used in the adhesive exhibited increased dry and wet strength values .

[0087] As above presented, increasing the amount of lignin in the binder composition used for preparing the adhesive has usually resulted in poor strength values . From the attached results , it was surprisingly seen that for the adhesives based on LPF700 the use of triacetin either alone or in combination of urea drastically increased the dry strength of the sandbar samples . By adding 1 weight-% of triacetin in the adhesive containing no urea, a 128 % of increase in dry strength was noted . The dry strength of these sandbar samples with high phenol replacement level was higher than for the commercial PF resins . From Fig . 1 it may also be noted that urea may not be needed in the adhesive and that at least the amount thereof may be decreased from what is used in commercial PF resins . Example 3 - Preparing samples and testing the strength properties

[0088] In this example an adhesive was prepared following the description in example 1 . A comparative example was al so prepared where triacetin was added to the lignin-based binder composition only after the lignin-based binder composition had been prepared by polymeri zation . The prepared adhesives were used to prepare sandbars as described in example 2 and the sandbar samples were analyzed in a similar manner as in example 2 for their dry strength . The results are presented below in Table 2 .

[0089] Table 2 . Prepared samples and the dry strength thereof From the above table one can see that preparing the lignin-based binder composition by carrying out the polymeri zation of the crosslinking agent and the polymeri zation agent in the presence of triacetin, highly affects the strength properties compared to merely adding triacetin to a pre-prepared lignin-based binder composition .

[0090] It is obvious to a person skil led in the art that with the advancement of technology, the basic idea may be implemented in various ways . The embodiments are thus not limited to the examples described above ; instead they may vary within the scope of the claims .

[0091] The embodiments described hereinbefore may be used in any combination with each other . Several of the embodiments may be combined together to form a further embodiment . An adhesive , the use , or the insulating wool product may comprise at least one of the embodiments described hereinbefore . It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments . The embodiments are not limited to those that solve any or all of the stated problems or those that have any or al l of the stated benefits and advantages . It wil l further be understood that reference to ' an ' item refers to one or more of those items . The term "comprising" is used in this specification to mean including the feature ( s ) or act ( s ) followed thereafter, without excluding the presence of one or more additional features or acts .

Claims

CLAIMS1. An adhesive, wherein the adhesive comprises a lignin-based binder composition, wherein: the lignin-based binder composition is prepared from crosslinking agent polymerized with polymerizable substance in the presence of triacetin,- at least 30 weight-% of the polymerizable substance originates from lignin, and- triacetin is used in an amount of 0.1 - 5 weight-% based on the total wet weight of the ligninbased binder composition.

2. The adhesive of claim 1, wherein 30 - 100 weight-%, or 40 - 99 weight-%, or 50 - 95 weight-%, or 60 - 90 weight-%, or 70 - 85 weight-%, of the polymerizable substance originates from lignin.

3. The adhesive of any one of the preceding claims, wherein the adhesive comprises the lignin-based binder composition in an amount of 65 - 99.9 weight-%, or 69 - 99 weight-%, or 75 - 98 weight-%, based on the total dry weight of the adhesive.

4. The adhesive of any one of the preceding claims, wherein the triacetin is used in an amount of 0.2 - 4 weight-%, or 0.4 - 3 weight-%, or 0.6 - 2.5 weight-%, or 0.8 - 2 weight-%, or 1.0 - 1.5 weight-%, based on the total wet weight of the lignin-based binder composition .

5. The adhesive of any one of the preceding claims, wherein the adhesive further comprises silane in an amount of 0.1 - 0.9 weight-%, or 0.2 - 0.7 weight- % , or 0.3 - 0.5 weight-%, based on the total dry weight of the adhesive.

6. The adhesive of any one of the preceding claims, wherein the adhesive further comprises ammonium sulphate in an amount of 0.5 - 15 weight-%, or 1 - 14 weight-%, or 2 - 13 weight-%, or 3 - 12 weight-%, or 4 - 11 weight-%, or 5 - 10 weight-%, or 6 - 9 weight-%, based on the total dry weight of the adhesive.

7. The adhesive of any one of the preceding claims, wherein the adhesive further comprises urea in an amount of 0.1 - 20 weight-%, or 0.2 - 16 weight-%, or 0.3 - 13 weight-%, or 0.5 - 9 weight-%, or 0.7 - 8 weight-%, or 1 - 7 weight-%, or 2 - 6 weight-%, or 3 - 5 weight-%, based on the total wet weight of the binder composition .

8. The adhesive of any one of the preceding claims, wherein the lignin-based binder composition has a viscosity of 10 - 300 mPa -s, 50 - 275 mPa -s, or 100 - 250 mPa -s, or 125 - 225 mPa-s.

9. Use of the adhesive of any one of claims 1 - 8 for producing an insulating wool product, a woodbased panel, a composite, a coating, a paint, a laminate, a film, a filter material, an abrasive, a foundry mold, or an insulating foam.

10. The use of claim 9, wherein the adhesive is used for producing an insulating wool product, wherein the insulating wool product comprises a fiber matrix selected from glass fiber, stone fiber, or slag fiber .

11. The use of triacetin in an adhesive comprising a lignin-based binder composition for producing an insulating wool product, a wood-based panel, a composite, a coating, a paint, a laminate, a film, a filter material, an abrasive, a foundry mold, or an insulating foam, wherein the lignin-based binder composition is prepared from crosslinking agent polymerized with polymerizable substance in the presence of triacetin, wherein at least 30 weight-% of the polymerizable substance originates from lignin, and the triacetin is used in the adhesive in an amount of 0.1 - 5 weight-% based on the total wet weight of the ligninbased binder composition.

12. The use of triacetin in the production of an adhesive comprising a lignin-based binder composition for increasing the strength of an insulating woolproduct produced with the adhesive, wherein the ligninbased binder composition is prepared from crosslinking agent polymerized with polymerizable substance in the presence of triacetin, wherein at least 30 weight-% of the polymerizable substance originates from lignin, and the triacetin is used in the adhesive in an amount of 0.1 - 5 weight-% based on the total wet weight of the lignin-based binder composition.

13. The use of any one of claims 11 - 12, wherein 30 - 100 weight-%, or 40 - 99 weight-%, or 50 - 95 weight-%, or 60 - 90 weight-%, or 70 - 85 weight-%, of the polymerizable substance originates from lignin.

14. The use of any one of claims 11 - 13, wherein triacetin is used in an amount of 0.2 - 4 weight- % , or 0.4 - 3 weight-%, or 0.6 - 2.5 weight-%, or 0.8 - 2 weight-%, or 1.0 - 1.5 weight-%, based on the total wet weight of the lignin-based binder composition.

15. The use of any one of claims 11 - 14, wherein the dry strength of the insulating wool product is increased by at least 10 % , or at least 13 % , or at least 20 % , or at least 30 % , or at least 50 % , as determined based on the sandbar method as disclosed in the description, when using triacetin in the ligninbased binder composition compared to using an adhesive prepared in an otherwise equal manner but without using triacetin in the lignin-based binder composition.

16. The use of any one of claims 11 - 15, wherein the wet strength of the insulating wool product is increased by at least 10 % , or at least 13 % , or at least 20 % , or at least 30 % , or at least 50 % , as determined based on the sandbar method as disclosed in the description, when using triacetin in the ligninbased binder composition compared to using an adhesive prepared in an otherwise equal manner but without using triacetin in the lignin-based binder composition.17 . An insulating wool product comprising a fiber matrix and an adhesive , wherein the adhesive comprises a lignin-based binder composition, wherein : the lignin-based binder composition is prepared from crosslinking agent polymeri zed with polymeri zable substance in the presence of triacetin,- at least 30 weight-% of the polymeri zable substance originates from lignin, and- triacetin is used in an amount of 0 . 1 - 5 weight-% based on the total wet weight of the ligninbased binder composition .18 . The insulating wool product of claim 17 , wherein the insulating wool product comprises a fiber matrix selected from glass fiber , stone fiber, or slag fiber .

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