Adhesion promoter for difficult-to-bond wood species for sustainable timber construction

Abstract

The invention relates to adhesive systems for lignocellulosic materials comprising a) a primer composition b) a 1-component polyurethane adhesive composition.

Description

[0001] 202300221 Foreign Filings 1 Adhesion promoter for difficult-to-bond wood species for sustainable timber construction Field of the invention The invention relates to adhesive systems for lignocellulosic materials consisting of an isocyanate (NCO)- containing adhesive formulation and an adhesion promoter based on alkoxylated fatty acid esters for the pretreatment of the substrate which improves the bonding of difficult-to-bond substrates. Prior art Concrete is the most important building material of our times. However, concrete production is an emissions-intensive industrial process that results in significant greenhouse gas emissions. Structural glued laminated timber construction is one solution for avoiding greenhouse gas emissions in the construction sector. Products in structural glued laminated timber construction such as OSB (oriented strand board), CLT (cross-laminated timber), GLT (glulam, glue-laminated timber) and LVL (laminated veneer lumber) consist of wood materials (for example wood lamellas, veneer, shavings, fibres, chemically-modified or infiltrated wood) and adhesives. Examples of adhesives are pMDI, PF and MF. Adhesives approved in the EU for load-bearing applications belong to the families of emulsion polymer isocyanate (EPI) adhesives (DIN EN16254 (2016)), phenoplastic and aminoplastic resins (DIN EN 301 (2018)) or polyurethane (PUR) adhesives (DIN EN 15425 (2017)) and must meet high strength requirements. A test to investigate the effect of moisture and heat on the strength of the adhesive join is the longitudinal tensile shear test on beech wood test specimens in the wet state after boiling for 6 h, as described in DIN EN 302-1 A4 (2017). Further important tests to investigate the effect of moisture are delamination tests, which are described for example in DIN EN 14080 (2013) Annex C and EN 302-2 (2017). Of the adhesive types mentioned, those having isocyanate functionality are particularly noteworthy, since these do not result in formaldehyde emissions during processing and cure at room temperature within practicable times. At present, structural glued laminated timber construction predominantly involves working with products based on softwood (usually spruce, occasionally fir, pine, larch or Douglas fir; further types of softwood are possible). This is also reflected in the current European standards for CLT (DIN EN 16351:2021) and GLT (DIN EN 14080:2013), which only apply to components made of softwoods and poplar. However, the increasingly rapidly changing climatic conditions and the threat from for example bark beetles mean that a transition to the processing of other lignocellulosic materials is necessary. For this reason, hardwoods, particularly beech and oak wood, are increasingly being used in structural glued laminated timber construction. For example the documents Z-9.1-679 (beech), Z-9.1-821 (oak) and EAD 130320-00-0304 (various hardwoods) for GLT and EAD 130010-01-0304 for GLT made of LVL lamellas have been created for this purpose. These documents for hardwood products likewise refer to the already mentioned delamination tests. 202300221 Foreign Filings 2 However, the problem arises that the currently available products for structural glued laminated timber construction based on hardwood that meet the abovementioned technical specifications (EAD) and general technical approvals (Z) are largely or exclusively bonded with aminoplasts and phenoplasts. Standard 1-component polyurethane adhesives (1K-PUR) do have the advantage that they do not result in formaldehyde emissions during processing, do not require any separate resin-curing agent handling and cure at room temperature within practicable times, however on hardwoods they often do not meet the strength requirements specified in the standards, particularly with respect to the delamination test. This problem with 1K-PUR adhesive formulations is known. One fundamental solution is the use of adhesive systems consisting of a primer (adhesion promoter) and the 1K-PUR adhesive formulation. To this end, the primer is applied to the wood first and only after a primer-specific exposure time is the adhesive formulation applied. The increasing importance of primers is demonstrated, inter alia, by the fact that primers were included under the name adhesion promoters in the draft standard with publication date 2022-01-07 for the new DIN EN 15425. However, unsolved challenges still occur in the case of the already known adhesive systems with 1K-PUR and primers for structural glued laminated timber construction. For example, US5543487 describes a primer based on hydroxymethylated resorcinol (HMR) that improves the bonding with epoxy adhesives and, as an overview study by Richter et al. (International Journal of Adhesion and Adhesives 113 (2022) 103070) shows, also improves the bonding by means of 1K-PUR. However, it is necessary for the HMR primer to be freshly produced and to react prior to application for a defined time, which must be neither undershot nor overshot. In addition, it is based on the toxicologically harmful chemicals formaldehyde and resorcinol, the processing of which requires a high level of safety measures. It is for these reasons that adhesive systems consisting of 1K-PUR and the HMR primer have not been adopted in industry. A structurally similar primer is disclosed in US5888655. This primer is a carbamate-functional novolac resin for aminoplast adhesives, the application of which is however restricted to aminoplast adhesives. US 5888655 does not comprise examples for the application on wood, or in adhesive systems with 1K- PUR. US2009191354 uses primer formulations consisting of a strong inorganic base and polyethylenimine (PEI) which have a pH of at least 11.5 and discloses their use for the bonding of hardwoods of various eucalyptus types. A tensile strength test that deviates from the above-described standards is described, which is used to show that the PEI primer increases the tensile strength of a 1K-PUR adhesive on various eucalyptus types. No information is however given as to whether this also applies in the wet state. Results of delamination tests, as required in the standards stated above, are not described. A further problem is that the strongly basic nature of the solutions makes the primer unattractive for industrial application. The bases described in said document containing NaOH and KOH can cause blindness if 202300221 Foreign Filings 3 they come into contact with the eyes and should therefore be sprayed only under particular safety precautions. Furthermore, the alkali metal hydroxides have a corrosive effect on metal. A further problem is the long exposure time of the PEI primer of 1 – 4 hours, which would slow down the throughput in industrial production. WO03093385 discloses an adhesive system consisting of a 1K-PUR and a primer, where a solution of polyvinyl alcohol, salts of dodecylbenzene sulfonic acid, copolymers based on ethene and vinyl acetate or a urea solution are possible as primer. The described adhesive system however requires that the wood first be planed and then additionally treated with sandpaper so that the standard requirements in the wet state in accordance with Standard ASTM D2559 are met. However, sandpaper is usually not used in an industrial-scale adhesion process, which is why the described primers are unsuitable for industrial production. The delamination test from ASTM D2559 is also only passed with softwood of longleaf pine. Douglas fir exhibits excessive delamination. Further wood types, particularly hardwoods, have not been tested, however it is to be assumed that many hardwoods cannot be bonded with these adhesive systems, since their standard-compliant 1K-PUR bonding is considered to be more difficult than the bonding of Douglas fir, which was not possible with the described primers. EP2848638 describes adhesive systems containing 1K-PUR and a primer composition, where the primer composition contains polyalkylene glycols and / or the mono- and / or diethers thereof, which have an OH number (OHN) of 30 mg KOH / g or less. The described primer composition may optionally also contain a solvent and / or a surfactant. EP2848638 states that these adhesive systems are particularly suitable for woods with a high proportion of extractives, in particular the extractive arabinogalactan. As wood types that contain a high proportion of arabinogalactan, the patent states almost exclusively softwoods (larch, hemlock, black spruce, Douglas fir, cedar, juniper). Sugar maple is mentioned as just one hardwood type that has a high proportion of arabinogalactan. The efficacy of the adhesive system is demonstrated only on larch. There is no use of hardwood, such as oak or beech, in the examples. The examples comprise exclusively delamination tests in accordance with EN 391 Method B. The standard has since been withdrawn, but the test is comparable to the currently valid delamination test from the successor Standard DIN EN 14080 (2013) Method B. According to DIN EN 14080 (2013), the maximum permissible delamination according to a delamination test in accordance with Method B corresponds to 4%. Of the nine shown inventive example adhesive formulations according to EP2848638, only four meet this requirement. This does show that some of the primers in the delamination test increase the water resistance of the adhesive join itself, however no results are given with regard to the effect of the primers on the shear strength of the bonded test specimens, for example according to longitudinal tensile shear tests in accordance with DIN EN 302-1 (2017) A1 or A4 or compressive shear tests in accordance with DIN EN 14080 (2013) Annex D. However, proof of shear strength is essential for industrial use. The examples shown have a primer exposure time of 10 min – 24 hours. Short exposure times would be desirable for industrial use, since exposure times of several minutes require an intermediate storage of the lignocellulosic materials (generally wood lamellas) to be bonded, which complicates the process and slows down production throughput. 202300221 Foreign Filings 4 EP2928977 is likewise dedicated to adhesive systems containing primers. The examples show how the use of Polysorbate 20 (Tween™ 20, polyoxyethylene (20) sorbitan monolaurate), Polysorbate 81 (Tween™ 81, polyoxyethylene (5) sorbitan monooleate) and Surfynol PSA-336 (formulation of ethoxylated 2,4,7,9-tetramethyl-5-decyne-4,7-diol) with specific wood species in specific tests of adhesive join strength leads to improved results. It is specifically shown that the bonding of Douglas fir, after pretreatment with a 5% Polysorbate 20 primer solution, measured in terms of shear strength and wood tear-out in the CSA 112.0 test, can be improved. The same primer solution likewise slightly improves the delamination resistance of southern yellow pine from an average of 6% to 1-4.6% (depending on primer exposure time and amount of the primer solution). The addition of 1% Surfynol PSA-336 to the 5% Polysorbate 20 primer solution made it possible to improve the delamination resistance on southern yellow pine from 4.6% to 1.8%. A 1% PSA-336 solution without Polysorbate 20 causes a delamination of 4.3%. Polysorbate 81 has a similar effect to Polysorbate 20 on southern yellow pine. A delamination of 5% on eucalyptus, 4% on ash, 8% on beech and 0% on birch is also shown with the primer solution made of 5% Polysorbate 20 and 1% PSA-336. Delaminations of 14% on ash, 5% on beech and 0% on birch were shown with a 0.5% Polysorbate 20 primer solution. On the basis of the results shown, both primer compositions would meet the requirements in the delamination test of Method B of DIN EN 14080 (2013) of at most 4% delamination only for birch, but birch is not considered to be a good construction timber due to its low load-bearing capacity and low durability. The general technical approval Z-9.1-765 of 11.8.2022 also describes the combination of the primer LOCTITE PR 3105 PURBOND®(as described in EP2928977) with adhesives of the LOCTITE HB SX9 PURBOND®line, which makes it possible to bond not only softwoods (spruces, fir, pines, Douglas fir) but also European beech in a standard-compliant manner. The adhesive system mentioned made of HB SX9 PURBOND®and LOCTITE PR 3105 PURBOND®is however not suitable for the use of larch. For the bonding of larch, the general technical approval specifies the primer PR 7010 based on the polyethers described in EP2848638. Apart from beech, the technical approval does not mention any further hardwoods. A disadvantage of Polysorbate 20-based primers (as described in EP2928977) in aqueous primer compositions is also the hydrolysis behaviour of Polysorbate 20. It is known to those skilled in the art that Polysorbate 20 is hydrolyzed in an aqueous environment (i.e. is split by water). For example, Leiss et al. (European Journal of Pharmaceutics and Biopharmaceutics, 152, 2020, 318 – 326) describe that the hydrolysis of Polysorbate 20 firstly influences the structural integrity of the respective formulation, since the emulsifying property of Polysorbate 20 is lost during hydrolysis. Secondly, the authors point out that the hydrolysis of Polysorbate 20 produces sparingly soluble fatty acids, which can lead to undesirable particles in the formulation. This is due to the fact that, in the context of the hydrolysis of Polysorbate 20, the ester bond between the hydrophilic sugar and / or polyether radical is cleaved and the resulting alkyl and / or alkenyl fatty acid are / is left behind without sufficiently solubility-imparting groups. 202300221 Foreign Filings 5 Object Despite some developments in the field, there still remains the unachieved object of providing a primer which enables the bonding of a broad range of woods. This should prepare not only the easy-to-bond softwoods, such as spruce, but also harder-to-bond softwoods with a high proportion of extractives, such as larches, and additionally hardwoods that to date have not been bondable with 1K-PUR in a standard- compliant manner, such as oak, in such a way that they can be bonded with 1K-PUR adhesives to form a material that, in the demanding DIN EN 14080 (2013) Method B delamination test, has only little delamination and at the same time has good shear strength. Furthermore, the primers to be provided should have a more advantageous hydrolysis behaviour in comparison with the established Polysorbate 20-based primer. Additionally, the object is to provide a method for bonding with the adhesive systems according to the invention and the uses thereof. Achievement The object was achieved by the provision of an adhesive system for the production of lignocellulosic composite materials, comprising a) a primer composition b) a moisture-curing 1-component polyurethane adhesive composition where the primer composition comprises: - 5-100% by weight of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function - 0-15% by weight of surfactants - 0-95% by weight of solvent. The object was able to be achieved by the provision of a primer composition based on alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function. It has been found that in particular primer compositions containing 5-100% by weight, particularly preferably 50-100% by weight, of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function are suitable as primer concentrate for the applications according to the invention in the adhesive system. It has also been found that in particular primer compositions containing 5-30% by weight of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function are suitable as applicable primer solution for the applications according to the invention in the adhesive system. 202300221 Foreign Filings 6 The alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function may be produced for example by alkoxylation of castor oil or hydrogenated castor oil. It has surprisingly been found that the use of a 10% by weight aqueous primer solution made of ethoxylated castor oil makes it possible to achieve a very significant improvement of 69-94% in comparison with non-inventive primer compositions in the delamination test on oak. The longitudinal tensile shear strength and compressive shear strength of bonded oak test specimens are also significantly improved by the pretreatment with the primer according to the invention in comparison with the non-inventive examples. In addition to beech and oak, the primer is also suitable for the bonding of other difficult-to-bond hardwood species, softwoods and other lignocellulosic materials. The primer compositions according to the invention contain alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function and optionally additional surfactants. The alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function may optionally be assigned to the surfactants; however, in the context of this invention they are intended to describe a separate group, independent of other surfactants. In the context of this invention, alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-functionrefer to the products of an alkoxylation of (poly)glycerol esters, where the alkoxylated (poly)glycerol esters contain at least one fatty acid that is linked via an ester bond and that does not have a pure alkyl chain (for example stearyl) or alkenyl chain (for example oleyl) but additionally has an alcohol function. Examples of such compounds are ethoxylated (poly)glycerol esters of ricinoleic acid, polyricinoleic acid, lesquerolic acid, 12-hydroxystearic acid, aleuritic acid, avenoleic acid, isanolic acid, myrmicacin or juniperic acid. Further such compounds may be obtained for example by the alkoxylation of (poly)glycerol esters of unsaturated fatty acids which have been derivatized by ozonolysis, epoxidation and / or hydroformylation and subsequent functionalization with alcohol functions. In particular, alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function conform to the general formula (I) where the repeating units may be arranged in any desired order, with k + l = 1 – 10 and R1= independently identical or different H, R2, R3radicals, where R2= independently identical or different polyether radicals, preferably identical or different polyether radicals of the general formula where the repeating units may be arranged in any desired order, 202300221 Foreign Filings 7 with a = 1–250, preferably 10 - 250, particularly preferably 10 - 100 b = 0–20, preferably 0 c = 0–20, preferably 0 d = 0–20, preferably 0 with the provisos a + b + c + d ≥ 5, a > b, a > c, a > d, R4= identical or different alkyl radicals that have 1 to 21 carbon atoms and optionally have ether functions, or aryl radicals that have 6-18 carbon atoms and optionally have ether functions, or H, preferably H, methyl, ethyl and phenyl and each R3radical = independently identical or different radicals cis configuration where the repeating units may be arranged in any desired order, with e = 1 - 21, preferably 13 - 17 f = 0 - 2, preferably 0 – 1 g = 0 - 3, preferably 0 - 1 h = 0 - 3, preferably 0 - 1 i = 0 - 2, preferably 0 - 1 202300221 Foreign Filings 8 j = 0 - 1, preferably 0 and where in (I) at least one of the independently identical or different R3radicals is present with g+h+i+j ≥ 1 and at least one R2radical is present. The slashes " / " in the R2and R3radicals stand for "or". This means for example that each of the R2radicals having the formula may independently conform to either the formula or the formula It is preferable here that [CR42CR42O] is not selected from the group consisting of [CH2CH2O], [CH(CH3)CH2O] and [CH2CH(CH3)O]. It is thus preferable that [CR42CR42O] is different from [CH2CH2O], [CH(CH3)CH2O] and [CH2CH(CH3)O]. It is also preferable that the number y of covalently directly bonded structural units [R2-R3] in a chain of repeating structural units having the formula [R2-R3]y is 1 - 10, particularly preferably 0 - 2. It is additionally preferable that the number z of covalently directly bonded structural units [R3-R3] in a chain of repeating structural units having the formula [R3-R3]z is 1 - 50, particularly preferably 0 - 1. It is also preferable that alkoxylated (poly)glycerol esters containing at least one OH- and / or ether- functional fatty acid component according to the invention contain 750 or fewer carbon atoms per molecule. It is further preferable that the alkoxylated (poly)glycerol esters containing at least one OH- and / or ether- functional fatty acid component are selected from the class of the glycerol esters and conform to the general formula (I) with k = 1 and l = 0. In the structural formulae shown for the described polymers, i.e. molecules having more than three identical repeating units in their structure, the indices indicate the amounts of the individual repeating units in the theoretical molecule number-averaged across the polymer distribution. In the individual molecules actually present, the specified repeating units may be present within the polymer distribution in blocks, in random order or in another order. An exception is formed by the structures that follow, which are provided with the headings "Examples of structures according to the invention present in ethoxylated castor oil" and "Examples of further structures according to the invention". The alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function are preferably selected from the group of the ethoxylated fatty acid glycerol esters, 202300221 Foreign Filings 9 particularly preferably from the group of the ethoxylated castor oils or ethoxylated hydrogenated castor oils. Example structures for alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function according to the invention, which conform to the general formula (I), and possible sources for their precursors are shown below:

[0002] 202300221 Foreign Filings 10

[0003] 202300221 Foreign Filings 11 It has been found that primers according to the invention based on alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function have a better hydrolysis behaviour than Polysorbate 20. Even if a part of the primers according to the invention is hydrolyzed, the resulting hydrolysis products still have surface activity and exhibit a better solubility than the alkanecarboxylic acids formed in the hydrolysis of Polysorbate 20, which means that disruptive precipitates are not formed. Surfactants The primers according to the invention contain 0-15% by weight from the group of water-soluble surfactants, water-dispersible surfactants and mixtures thereof. Preferred surfactants are organically modified siloxanes, acetylenediol derivatives, alkoxylated fatty alcohols, sulfosuccinates, alkylpolyglycosides and biosurfactants such as RHEANCE®One. Moisture-curing 1-component polyurethane adhesive composition The NCO-containing adhesive formulations for the bonding of lignocellulosic materials in each case have an NCO content of 1-32% by weight, which was measured in accordance with DIN EN ISO 11909 (2007). The main component of the NCO-containing adhesive formulations is either polymeric methylene diphenyl diisocyanate (pMDI) or an isocyanate prepolymer consisting of at least one diisocyanate, for example one or more isomers of methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated methylene diphenyl diisocyanate and / or a higher isocyanate, for example pMDI or trimers, oligomers or homopolymers of the aforementioned diisocyanates and / or mixtures thereof comprising two or more of said isocyanates and at least one isocyanate-reactive substance used in a substoichiometric amount, usually an alcohol compound and / or amine compound, often in the form of polymers, i.e. polyols composed of different monomers. Particularly preferably, the moisture-curing 1-component polyurethane adhesive compositions are characterized in that - they contain prepolymers which are formed by reaction of polyether polyols and aromatic isocyanates having two or more NCO functionalities and - they have an NCO content of 1-28% by weight, preferably an NCO content of 1-20% by weight, particularly preferably an NCO content of 10-20% by weight. Likewise preferably, 1-component polyurethane adhesive compositions are characterized in that they contain polymeric diphenylmethane diisocyanate (pMDI) as main component and have an NCO content of 28 – 32% by weight. Formulations and also production processes and in some cases subsequent mixtures of individual separately produced prepolymers are known to those skilled in the art, are well described, such as in WO 202300221 Foreign Filings 12 02 / 48232 or US 6133398 for example, and largely form the basis of polyurethane-based adhesive chemistry. In addition to the prepolymers and / or pMDI, the NCO-containing adhesive formulations may contain further additives or / and auxiliaries. By way of example, crosslinkers, fillers, catalysts, defoamers, stabilizers, acids, antioxidants, UV stabilizers, biocides and other ageing stabilizers, viscosity modifiers, plasticizers, dyes, solvents, dispersants, adhesion promoters, flame retardants, hydrolysis stabilizers, desiccants, activators and further auxiliaries and mixtures thereof may be present. The crosslinkers are preferably selected from the group of oligomers or homopolymers of hexamethylene diisocyanate, one or more mixed isomers of methylene diphenyl diisocyanate, pentamethylene diisocyanate and isophorone diisocyanate and mixtures thereof. Suitable fillers are metal oxides, for example titanium dioxide, aluminium oxide, zinc oxide, fumed silicon dioxide, surface-treated silicas, sheet silicates such as kaolin, mica, bentonite, or talc, and carbon black. Likewise suitable are biobased fillers such as cornflour, wheat flour and ground nutshells. Further preferably, the fillers are selected from the group of CaCO3, reinforcing fibres, organic polymers, preferably lignin or cellulose, and mixtures thereof. Suitable catalysts include tin(II) salts of carboxylic acids, alkyltin(IV) carboxylates, tertiary amines, amino alcohols, alkali metal hydroxides and alkali metal alkoxides. Preferred catalysts of the NCO-containing adhesive formulations according to the invention are selected from the group of Polycat®DMDEE (dimorpholinodiethyl ether) Polycat®557 (from Evonik, Germany), dialkyltin(IV) dicarboxylates, dialkyltin(IV) thiols, dialkyltin(IV) thioglycolates and mixtures thereof. It is additionally possible to use a large number of further catalysts, for example those mentioned in EP 1425328. Plasticizers, solvents and thinners suitable for the 1K-PUR adhesive composition are esters, for example castor oil, diesters of phthalic acid, aliphatic diacids, such as adipic acid, or triacids, such as citric acid, and further plasticizers, solvents and thinners known to those skilled in the art. Suitable desiccants for preventing premature curing in the event of moisture ingress during storage and preparation are for example molecular sieve powder, silanes, diethyl malonate and alkyl phenol acrylates. Hydrolysis stabilizers are substances that are intended to reduce the hydrolysis of the fully cured adhesive join. Suitable antioxidants and UV stabilizers are for example phenol derivatives, thioesters, phosphates or sterically inhibited amines marketed for this purpose. 202300221 Foreign Filings 13 Suitable adhesion promoters (not in the function as primer pretreatment) in the 1K-PUR adhesive composition are di- or trialkoxysilanes. Suitable flame retardants are for example bromoalkyl or chloroalkyl phosphate esters, melamine, aluminium oxide hydrate, red phosphorus, ammonium polyphosphate, antimony trioxide. Suitable defoamers, hydrolysis stabilizers, antioxidants and viscosity modifiers are known to those skilled in the art. There are various NCO-containing adhesive systems that contain NCO-containing adhesive formulations. In addition to the already mentioned adhesive formulations, NCO-containing adhesive systems may also contain primers. These are used to treat the wood materials to be bonded before applying the adhesive composition, thereby achieving an improvement in adhesive strength, particularly in wet adhesive strength. Solvent Suitable solvents for the primer composition are DMSO, water, alcohols, glycols, levoglucosenone, other polar solvents and mixtures thereof. A preferred solvent for the primer composition is water. The adhesive systems according to the invention contain primer compositions containing 0-95% by weight, preferably 0-50% by weight, very particularly preferably 75-95% by weight of solvent. A further aspect of the invention is a method for bonding with the adhesive systems according to the invention, characterized by a) provision of at least two identical or different lignocellulosic materials, b) optionally: production of an aqueous primer composition by addition of water to a primer composition according to the invention, c) application of the aqueous primer composition, d) optionally: intermediate storage of the primer-treated lignocellulosic materials for an exposure time, e) application of the 1-component polyurethane adhesive composition to at least one lignocellulosic material, f) bringing together of the at least two lignocellulosic materials, g) compression of the lignocellulosic materials, h) optionally: post-curing of the bonded lignocellulosic materials by way of storage. For method step c), it is possible to use aqueous primer compositions in the application amount of 1-500 g / m2, preferably 5-100 g / m2, particularly preferably 10-50 g / m2, based on the surface materials and / or boards (for example lamellas) and / or finger joints to be bonded. For lignocellulosic fibres and particles (for example wood chips), it is possible to use 0.001 – 0.2 g of primer composition per g of lignocellulosic material. 202300221 Foreign Filings 14 Method steps c) and e) may optionally also be performed simultaneously by means of two separate application systems. In the optional method step b), an aqueous primer composition is produced by addition of water to a primer composition according to the invention. The primer composition may contain 5-100% by weight of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether- function. The content of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function may alternatively be 50-100% by weight or 5-30% by weight. Depending on the concentration of this component, it is possible to produce an applicable primer composition by the addition of water. For method step e), it is possible to use 1-component polyurethane adhesive amounts of 90-350 g / m2, preferably 120-250 g / m2, particularly preferably 140-200 g / m2, based on the surface materials and / or boards (for example lamellas) and / or finger joints to be bonded. For lignocellulosic fibres and particles (for example wood chips), it is possible to use 0.005 – 0.5 g of NCO-containing adhesive formulation per g of lignocellulosic material. Method steps c) and e) may be performed by spraying, knife coating, dipping, brushing, passing through a primer or adhesive curtain or application using nozzles or cartridges. Method steps d), g) and h) may optionally be carried out at elevated temperature, and step g) also at elevated pressure, in order to achieve a fast-curing and firm adhesive join. For method step g), a pressure of 0.4-2 N / mm2, preferably 0.6-1.4 N / mm2, may be used for surface bonding and narrow-side bonding, and a pressure of 5-15 N / mm2, preferably 7.5-10 N / mm2, may be used for finger jointing. For method steps d) and g), a temperature of 0-210°C, preferably 15-40°C, may be used, for example by means of a heated ambient atmosphere or temperature-controlled presses. Further claimed are the cured adhesive systems comprising a primer composition and a moisture-curing 1-component polyurethane adhesive composition. In particular, the use of the adhesive system according to the invention for the bonding of lignocellulosic materials is claimed. Particular preference here is given to bondings of sawn timber, fibres, chips, boards, wood splints, veneer, parquet, cross-laminated timber, glue-laminated timber, laminated veneer lumber, solid wood boards, veneer plywood, I-joists, TJI joists, scrimber products and shavings. The bonding of hardwoods, softwoods, grasses, beech woods, oak woods, sweet chestnut and other Fagaceae, ash and other Oleaceae, birch and other Betulaceae, eucalypts, robinia, bangkirai, teak, 202300221 Foreign Filings 15 meranti, ekki, merbau, abachi, wenge and other tropical timbers, Salicaceae, Douglas fir, pines, larches and other Pinaceae, hinoki cypress, Chinese fir, Japanese cedar and other Cupressaceae, acetylated wood, bamboo, Miscanthus, rice straw, cereal straw and hemp shives is particularly preferably claimed here. There is a broad field of application for the use of the adhesive systems according to the invention. Bonded lignocellulosic materials are used in various application markets, for example in furniture construction, in structural glued laminated timber construction, in vehicles, in boat construction, in parquet and facades. It has been found that the adhesive systems according to the invention are also suitable for the bonding of lignocellulosic materials with other materials, for example metal, plastics, in particular with foam materials, ceramics and glass. Examples All stated percentages relating to the compositions or formulations refer to % by weight based on the total weight of the respective composition, unless expressly stated otherwise. Conditions for the production of the wood test specimens: The bonded lignocellulosic materials made of hardwood were produced in accordance with Standards DIN EN 14080 (2013) and DIN EN 302-1 (2017). Unsteamed beech and oak wood boards were used, these having a standard-compliant bulk density, wood moisture content, length, thickness and width. Creation of the test specimens for the longitudinal tensile shear tests: The 130 x 150 x 5 mm boards were placed in a climatic chamber at a temperature of 18-22°C and a relative humidity of 60-70% for at least one week. For the production of in each case up to 5 wood test specimens, two boards were bonded. To this end, the boards were first pretreated using an airbrush application system with the specified amount of the primer solution or, for the reference, with the same amount of water. In the case of non-primed references, this step was skipped. After a waiting time of 10 min, the specified amount of the 1K-PUR adhesive composition was applied and the wood boards were placed one on top of the other and lightly pressed. This was followed by compression using a hydraulic press at various pressing pressures and pressing times at room temperature of 20-30°C, after which the bonded materials were stored for 7-14 days under normal climatic conditions. The test specimens were cut to size using a CNC router, by making two offset cuts at right angles to the wood fibre in accordance with the standard. In addition, the two outer sections parallel to the fibre direction were cut away at a distance of 7.5 mm from the edges and discarded. 202300221 Foreign Filings 16 Creation of the glue-laminated timber for the delamination and compressive shear tests: For the delamination and compressive shear tests, glue-laminated timbers were produced from in each case six lamellas of beech or oak in accordance with DIN EN 14080 (2013). Like in the production of the longitudinal tensile shear test specimens, the wood was conditioned before the bonding in a climatic chamber and pretreated immediately before the bonding using an airbrush application system with primer or water (reference), where a waiting time of 10 min between primer application and adhesive application was selected. Creation of test specimens from the grass Miscanthus The raw material used for the production of a board material and subsequent rod-shaped test specimens made of Miscanthus (Miscanthus giganteus) was Miscanthus stem pieces produced from 160 mm-long Miscanthus stems which were split into four in the longitudinal direction and from which the parenchyma was removed. The Miscanthus stem pieces were placed in a climatic chamber at a temperature of 18-22°C and a relative humidity of 60-70% for at least one week. For the production of in each case up to three test specimens with dimensions of 160 x 40 x 4 mm, 60 g of Miscanthus stem pieces was used. To this end, the Miscanthus stem pieces were first sprayed using an airbrush application system with 0.5 g of the primer solution. In the case of the production of test specimens for the non-inventive reference without primer, this step was skipped. The press mask needed for the pressing and the press punch were treated before the pressing with a suitable release agent in order to prevent adhesion thereto. After an exposure time of the primer of 10 min, the Miscanthus stem pieces were placed parallel to one another in the press mask and 6.6 g of the pMDI adhesive was applied between the layers. The press punch was applied at the end. This was followed by compression using a hydraulic press at a pressing pressure of 1.2 N / mm², a pressing time of 120 min and a temperature of 90°C, after which the bonded Miscanthus material boards were stored for 1-2 days under normal climatic conditions. The board was cut into test specimens (160 x 40 x 4 mm) using a CNC router. The two outer regions of the Miscanthus material board parallel to the fibre direction at a distance of 20 mm from the edges were discarded. Aftertreatments A4: The longitudinal tensile shear test specimens were treated in accordance with the aftertreatment A4 described in DIN EN 302-1 (2017). For samples in accordance with A4, the samples were first boiled in water for 6 hours and then, in a departure from the standard, immersed in cold water overnight instead of just for two hours, and measured wet in the longitudinal tensile shear test. Procedure for the longitudinal tensile shear test: The test specimens were clamped parallel to the direction of stress in the clamping jaws of the tensile testing machine at a distance of 90 mm and tested with the increase in load of 2.0 [± 0.5] kN / min specified in Standard DIN 302-1 (2017). The test was judged to have ended when the test specimen 202300221 Foreign Filings 17 fractured. The specified longitudinal tensile shear strength is the mean value of the determined longitudinal tensile shear strengths of the tested test specimens. Test specimens that were significantly twisted and were not able to be clamped in the jaws without generating a substantial stress in the adhesive join at right angles to the fibre direction were not included in the calculation of the mean value. Such test specimens often already delaminate before the longitudinal tensile shear test while being clamped in the clamping jaws. Determination of wood tear-out: After carrying out the longitudinal tensile shear test, the wood tear-out is determined in each case by analysing the two test specimen fragments using a Keyence VR-5000 optical 3D profilometer. In this test, raised areas or depressions respectively higher or deeper than 0.1 mm are considered to be wood tear- out. The wood tear-out after carrying out the compressive strength test is determined using microscopy. The specified wood tear-outs are each mean values of all wood tear-outs of the respective test specimens. Procedure for the compressive shear tests: For the compressive shear tests, in each case five test specimens with a width of 50 mm and a thickness of 40 mm of both sides were taken from the glue-laminated timber in accordance with the description in DIN EN 14080 (2013) Appendix D. The compressive shear tests were then carried out according to the method described in DIN 52187 (1979). The specified compressive shear strength is the mean value of the 10 test specimens. Determination of bending modulus of elasticity: The Miscanthus material test specimens were placed on the support rollers of the test machine with a spacing of 100 mm and were tested in accordance with Standard DIN EN 310 (1993). The test was ended after at the latest 6% deformation or after the sample had fractured. The specified modulus of elasticity is the mean value of the determined moduli of elasticity of the tested test specimens. Procedure for the delamination tests: For the delamination tests, in each case three test specimens were sawn from the glue-laminated timber (left, middle and right) and subjected to one or two (Example 10) test cycles in accordance with DIN EN 14080 (2013) Annex C Method B. These consist of a watering phase (30 min, 15-30 kPa reduced pressure, 120 min 600 – 700 kPa elevated pressure) and a drying phase (several hours at 70±5°C and a relative humidity of 9±1% with an air flow of 2.5 ± 0.5 m / s). This involved drying the species to an average of 106% of their original mass. The average drying time was 18 hours. The delamination is then evaluated using a microscope as described in EN 14080 (2013). The specified delamination values are the average delaminations of all adhesive joins in all three test specimens ("Mean value of the delaminations of all adhesive joins") and the fraction of delamination of the adhesive join having the highest fraction of delamination of all adhesive joins in all three test specimens ("Delamination in the adhesive join with the greatest extent of delamination"). 202300221 Foreign Filings 18 Measurement of penetration time: To measure the penetration times, use was made of a contact angle measuring instrument (DSA 100 model) from Krüss. Beech wood conditioned to a wood moisture content of 12% was placed into a climatic chamber and a droplet of 10 μl of the primer solution or water (reference) was applied using a cannula. The time needed for the droplet to completely infiltrate into the wood was then measured. The specified measured values are average values of in each case 3 contact angle measurements. Materials The 1-component polyurethane adhesive compositions used are commercially available. LOCTITE®HB S309 PURBOND from Henkel AG & Co. KgaA Jowapur®681.10 from Jowat SE pMDI (9016-87-9, number-average molar mass according to manufacturer's specifications of 340 Da) from Merck KGaA The tested primer compositions were obtained by dilution of primers with water. By way of example, in the case of Primer A according to the invention, a 10% aqueous solution of POE(36) castor oil was produced. POE here stands for polyoxoethylene and (36) stands for the molar proportion of oxoethylene units per castor oil unit. The primers are either commercially available or were produced according to established alkoxylation methods, which are briefly described below. The prior art includes various documents in which alcohols, carboxylic acids or esters are used as starter compounds for the alkoxylation reaction. A good overview of polyoxyalkylenes and processes for preparing polyoxyalkylenes is given for example by "N. Schönfeldt, Surface Active Ethylene Oxide Adducts, Pergamon Press, 1969". The alkoxylated compounds used in the context of this invention, if they were not acquired commercially, were prepared according to the following method: In the first step, a starter compound is reacted using a catalyst with epoxides, for example ethylene oxide or propylene oxide or any desired mixtures of these epoxides. By way of example, in the case of the POE(36) castor oil according to the invention for producing Primer A according to the invention 1 part castor oil was initially charged as starter compound and 36 parts ethylene oxide were used as epoxide. "Part" refers here to the relative molar proportion, not to the mass fraction. Catalysts used for the alkoxylation reaction are the alkaline catalysts known to those skilled in the art, such as potassium hydroxide, potassium hydroxide solution, sodium methoxide or potassium methoxide, or double metal cyanide compounds. Starter compound and catalyst are initially charged in the reactor at the start of the process prior to the metered addition of epoxide, with it being necessary to adjust the amount of catalyst so as to give sufficient catalytic activity for the process. The reaction temperature in the first step is preferably 80°C to 220°C, particularly preferably 100°C to 180°C. The pressure in the first step is preferably 0.5 bar to 20 bar, preferably 1.0 bar to 12 bar (absolute). The epoxy monomers may be used in pure or mixed form, such that homopolymers or random copolymers are obtained. After the metered addition of a first monomer or a monomer mixture, further monomer may be metered in, such that block structures are obtained. A further epoxide can also be metered continuously over time into an epoxide already present in the reaction mixture, so as to give rise 202300221 Foreign Filings 19 to an increasing concentration gradient of the epoxide added continuously. The correlations between metered addition and product structure are known to those skilled in the art. The end of the epoxide addition is typically followed by a period of further reaction to allow the reaction to proceed to completion. The further reaction can for example be carried out by continued reaction under reaction conditions (i.e. maintenance for example of the temperature and of the pressure) without addition of reactants. Preferably, the further reaction is effected with mixing of the reaction mixture, especially with stirring. In an optional second step, residual monomers are removed in a vacuum distillation and, if required, the reaction product is neutralized with an acid such as lactic acid, acetic acid, propionic acid or phosphoric acid, and the salts formed are optionally removed by filtration. In principle, it is also possible to perform further modifications, for example to add an additional esterification. In the case of POE(20) castor oil dioleate, for example an esterification with two parts of oleic acid is carried out after completion of alkoxylation. Reactors used for the alkoxylation in the first process step may in principle be any suitable reactor types that allow control over the reaction and its exothermicity. The first process step can be effected continuously, semi-continuously or else batchwise, in a manner known in chemical engineering. Non-inventive primers POE(5) 1-undecanyl ether POE(7) monooleate POE(34) glyceryl stearate (mono / diethoxy and mono / distearate) POE(40) monostearate (at about 1% and above the compound is no longer water-soluble, this being why a 0.5% solution was used, from TCI Deutschland GmbH, Deutschland) TEGO®Humectant 7000 (from Evonik Industries AG, Germany) LOCTITE PR 3105 PURBOND®(from Henkel AG & Co. KgaA, Germany) BREAK-THRU®S 301 (surface-active siloxane derivative, from Evonik Industries AG, Germany) SURFYNOL®485 (acetylenediol derivative, from Evonik Industries AG, Germany) SURFYNOL®AS 5040 (acetylenediol derivative, from Evonik Industries AG, Germany) SURFYNOL®AS 5060 (acetylenediol derivative, from Evonik Industries AG, Germany) SURFYNOL®AS 5160 (alkyl sulfosuccinate, from Evonik Industries AG, Germany) TEGO®Care PS MB (methyl glucose sesquistearate, from Evonik Industries AG, Germany) Sodium lauryl sulfate (SDS, from Merck KGaA, Germany) Poloxamer 188 (poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) Kolliphor®P 188, OHN = 14 mg KOH / g, from Merck KGaA, Germany) Sodium dodecylbenzenesulfonate (SDBS, from Merck KGaA, Germany) Primer compositions according to the invention Primer A: 10% POE(36) castor oil in water Primer B: 5% POE(20) castor oil dioleate in water Primer C: 10% POE(40) hydrogenated castor oil in water 202300221 Foreign Filings 20 Primer D: 10% POE(36) castor oil + 10% RHEANCE®One (from Evonik Industries AG, Germany) in water Primer E: 18.9% POE(36) castor oil + 13.1% RHEANCE®One (from Evonik Industries AG, Germany) + 1% SURFYNOL®AS 5040 (from Evonik Industries AG, Germany) in water Primer F: 20% POE(36) castor oil in water Primer G: 10% POE(36) castor oil + 5% RHEANCE®One (from Evonik Industries AG, Germany) in water Primer H: 10% POE(36) castor oil + 10% RHEANCE®One (from Evonik Industries AG, Germany) + 1% SURFYNOL®AS 5040 (from Evonik Industries AG, Germany) in water Example 1: Longitudinal tensile shear test in accordance with DIN EN 302-1 (2017) A4 with and without primer Substrate: Beech wood (Fagus sylvatica) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing pressure: 1.28 N / mm² Primer Pressing Longitudinal tensile Wood tear-out Number of composition time shear strength test [N / mm2] specimens Without primer 75 min 5.9 0% 5 Primer A 75 min 7.9 74% 10 Example 1 shows that the use of primers according to the invention significantly increases the longitudinal tensile shear strength in the longitudinal tensile shear test. Whilst the absence of a primer results exclusively in a cohesive fracture within the adhesive join, the wood tear-out (wood fracture proportion) when using Primer A is 74%. Example 2: Longitudinal tensile shear test in accordance with DIN EN 302-1 (2017) A4 at lower pressing pressure Substrate: Beech wood (Fagus sylvatica) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing pressure: 0.80 N / mm² Primer Pressing Longitudinal tensile Wood tear- Number of composition time shear strength out test [N / mm2] specimens Only water as 75 min The adhesive join of the three bonded 130 x 150 mm board primer pairs tears within one hour after the press bonding due to the stresses in the wood. 202300221 Foreign Filings 21 Primer A 75 min 6.6 69% 5 Example 2 shows that, in comparison to the use of water as primer, the primers according to the invention accelerate the curing reaction in such a way that the press bonding can be carried out at low pressing pressures in only 75 min. For better comparability of the longitudinal tensile shear strength of primers according to the invention with non-inventive primers that do not have such acceleration of the bonding at a low pressing pressure of 0.8 N / mm², the tests that follow (Example 4) are carried out at an increased pressing pressure of 1.28 N / mm². Example 3: Penetration time Substrate: Beech wood (Fagus sylvatica) Primer Penetration time [min:s] Only water 1:55 Primer A 0:27 An important property of a primer is to penetrate into the wood within a short time in order to not delay the subsequent adhesive application and further subsequent steps for long. A short penetration time ensures that the wood workpieces require only brief intermediate storage, if any. Example 3 shows that primers according to the invention, such as Primer A, significantly reduce the penetration time in comparison with the exclusive use of water as primer. For better comparability of the results of primers according to the invention with non-inventive primers that do not have a short penetration time, all bondings shown are carried out with a sufficiently long primer exposure time of 10 min in order to ensure the penetration of each primer solution. Example 4: Longitudinal tensile shear test in accordance with DIN EN 302-1 (2017) A4 of non-inventive primers in comparison with Primer A according to the invention Substrate: Beech wood (Fagus sylvatica) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing pressure: 1.28 N / mm² Primer Compound class Longitudinal Wood tear- Number of composition tensile shear out test strength [N / mm2] specimens BREAK-THRU®S Surface-active siloxane 6.7 not 10 301 (2% aqueous derivative measured solution) SURFYNOL®AS Alkyl sulfosuccinate The adhesive join of the two bonded 5160 (3.7% 130 x 150 mm board pairs tears within one hour aqueous solution) after the press bonding. 202300221 Foreign Filings 22 SURFYNOL®485 Acetylenediol derivative 7.2 26% 10 (1% aqueous & polyol with MW solution) < 5000 Da TEGO®Humectant Alkoxylated alcohol & 4.7 not 5 7000 (10% polyol with MW measured aqueous solution) < 5000 Da POE(5) 1- Alkoxylated alcohol 6.7 50% 10 undecanyl ether (1% aqueous solution) Methyl glucose Alkyl polyglucoside & 2.7 not 5 sesquistearate (5% polyol with MW measured aqueous solution) < 5000 Da POE(40) Alkoxylated fatty acid 5.3 20% 2 monostearate (10% aqueous solution) POE(7) Alkoxylated fatty acid 3.9 not 5 monooleate measured (0.5% aqueous solution) Poloxamer 188 (1% Polyalkylene glycol with 7.0 18% 10 aqueous solution) OHN < 30, as claimed in EP2848638B1 Sodium Sulfated surfactant, as 7.1 22% 10 dodecylbenzenesul claimed in fonate (1% WO03093385A2 aqueous solution) Sodium lauryl Sulfated surfactant, as 6.4 42% 10 sulfate (1% claimed in aqueous solution) WO03093385A2 Primer A Alkoxylated 7.9 74% 10 (poly)glycerol esters containing at least one OH- and / or ether- functional fatty acid component EP2928977A1 claims in general all adhesive systems having a primer constituent that either contains a polyol with a molecular weight below 5000 daltons and / or contains surface-active compounds from the 202300221 Foreign Filings 23 following list: surface-active siloxane derivatives, alkyl polyglucosides, alkoxylated fatty acids, alkoxylated alcohols, alkyl sulfosuccinates, acetylenediol derivatives. Example 4 shows that such a broad substance class definition primarily includes compounds that are only poorly suitable, if at all, as primers, and that primers according to the invention are superior to the structures from the broad substance class definition in their effect as primers in terms of the adhesive join strength. It is also shown that primers according to the invention are superior to polyethers with OHN < 30 from EP2848638B1 and salts of dodecylbenzene sulfonic acid from WO03093385A2. Example 5: Longitudinal tensile shear test in accordance with DIN EN 302-1 (2017) A4 of non-inventive primers in comparison with Primers B and C according to the invention Substrate: Beech wood (Fagus sylvatica) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing pressure: 1.28 N / mm² Primer Compound class Longitudinal Wood tear- Number of composition tensile shear out test strength [N / mm2] specimens Primer B According to the 7.5 38% 5 invention: alkoxylated (poly)glycerol ester containing at least one OH- and / or ether- functional fatty acid component Primer C According to the 7.0 57% 5 invention: alkoxylated (poly)glycerol ester containing at least one OH- and / or ether- functional fatty acid component POE(34) glyceryl Non-inventive: 5.3 not 5 stearate Alkoxylated glycerol ester measured (mono / diethoxy and which does not contain an mono / distearate) OH- and / or ether- (5% aqueous functional fatty acid solution) component Example Table 5 shows with Primer B and C two further primers according to the invention from the compound class of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least 202300221 Foreign Filings 24 one OH- and / or ether-function which result in similarly good longitudinal tensile shear strengths as Primer A. In comparison with Primers A – C according to the invention, a non-inventive primer based on an alkoxylated glycerol ester which prepared from fatty acids which does not comprise an OH- and / or ether- functiongives worse longitudinal tensile shear results. Example 6: Compatibility of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function with other surfactants as primer Substrate: Beech wood (Fagus sylvatica) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing pressure: 1.28 N / mm² Pressing time: 75 min Primer Longitudinal tensile shear Wood tear-out Number of composition strength [N / mm2] test specimens Primer D 8.1 71% 10 Primer E 8.1 60% 10 Example Table 6 shows that alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function according to the invention can be combined with further surfactants in order to additionally increase the tensile strength. Example 7: Longitudinal tensile shear test in accordance with DIN EN 302-1 (2017) A4 on difficult-to-bond oak wood Substrate: Oak wood (Quercus robur) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing pressure: 1.28 N / mm² Pressing time: 75 min Primer composition Longitudinal tensile shear Number of strength [N / mm2] test specimens Primer A 7.2 10 LOCTITE PR 3105 5.7 10 PURBOND®(as a 10% aqueous solution) In comparison with LOCTITE PR 3105 PURBOND®(10% aqueous solution), which is suitable according to the general technical approval No. Z-9.1-765 in combination with LOCTITE PURBOND®HB S309 for the bonding of beech lamellas, Primer A according to invention has the advantage that it produces good 202300221 Foreign Filings 25 longitudinal tensile shear strengths not only on beech, but also on other difficult-to-bond hardwood species, such as the ring-porous species oak. Example 8: Delamination test in accordance with DIN EN 14080 (2013) Method B with oak and beech Substrate: Oak wood (Quercus robur) and beech wood (Fagus sylvatica) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing pressure: 1.2 N / mm² Pressing time: 150 min Primer composition Mean value of the delaminations of all adhesive joins Oak wood Beech wood Non-inventive: 99% 78% 0% primer, only water Non-inventive: 99% 59% SURFYNOL®AS 5040 Non-inventive: 74% 0.1% LOCTITE PR 3105 PURBOND®(as a 10% aqueous solution) Inventive: 4.8% 0.0% Primer A Example Table 8 shows that Primer A according to the invention, unlike the non-inventive primer compositions, is capable of bonding oak without most of the adhesive joins coming apart in the delamination test in accordance with DIN EN 14080 (2013) Method B. Example 9: Delamination test in accordance with DIN EN 14080 (2013) Method B with oak Substrate: Oak wood (Quercus robur) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing time: 150 min Primer composition Pressing Mean value of the Delamination in pressure delaminations of all the adhesive adhesive joins join with the greatest extent of delamination Primer A 1.0 N / mm² 3.7% 22% Primer F 1.2 N / mm² 0% 0% 202300221 Foreign Filings 26 Primer G 1.2 N / mm² 1.9% 16% Primer H 1.2 N / mm² 0.9% 11% Example Table 9 shows that with the primers according to the invention, it was possible for the first time to achieve the maximum delamination value specified in DIN EN 14080 (2013) for Method B of 4% (mean value of the delamination of all adhesive joins) and the maximum delamination value of a single adhesive join of 30% for the bonding of oak with a 1-component polyurethane adhesive composition. The adhesive system according to the invention thus also satisfies the requirements of the American standard for glue- laminated timber ANSI / APA PRG 320-2019, which specifies 5% as the maximum delamination. Since oak is considered to be one of the most difficult-to-bond hardwoods, it can be assumed that the adhesive systems according to the invention containing 1-component polyurethane adhesive compositions, unlike other 1-component polyurethane adhesive systems, are also suitable for most other hardwoods in addition to oak and beech. Example 10: Delamination test with two test cycles in accordance with DIN EN 14080 (2013) Method B with oak Substrate: Oak wood (Quercus robur) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing time: 150 min Primer composition Mean value of the Delamination in the delaminations of all adhesive join with adhesive joins the greatest extent after two test cycles of delamination after two test cycles Primer F 0.1% 2% In accordance with DIN EN 14080 (2013), two of the three Primer F-treated test specimens from the delamination test from Example Table 9 were sent to a second test cycle, in which the delamination barely increased and standard-compliant results were still obtained. Example 11: Compressive shear test in accordance with DIN EN 14080 (2013) on bonded oak and beech test specimens Substrate: Oak wood (Quercus robur) and beech wood (Fagus sylvatica) Primer: 20 g / m2Adhesive: 200 g / m2LOCTITE PURBOND®HB S309 Pressing pressure: 1.2 N / mm² Pressing time: 150 min 202300221 Foreign Filings 27 Primer composition Compressive shear strength [N / mm2] Oak wood Beech wood Non-inventive: 12.6 15.3 0% primer, only water Non-inventive: 12.4 17.3 LOCTITE PR 3105 PURBOND®(10% aqueous solution) Non-inventive: 12.1 16.8 SURFYNOL®AS 5040 (1% aqueous solution) Inventive: 14.8 18.0 Primer A Inventive: 16.4 not measured Primer F Inventive: 16.3 not measured Primer G Inventive: 17.2 not measured Primer H Like in the longitudinal tensile shear test, the primers according to the invention also exhibit an improvement in the strength of the adhesive join in the compressive shear test in accordance with DIN EN 14080 (2013). Example 12: Longitudinal tensile shear test in accordance with DIN EN 302-1 (2017) A4 with oak wood test specimens with a further 1K-PUR adhesive in conjunction with Primer A according to the invention Substrate: Oak wood (Quercus robur) Primer: 20 g / m2Adhesive: 200 g / m2of Jowapur® 681.10 Pressing pressure: 1.28 N / mm² Pressing time: 20 min Number of test specimens per longitudinal tensile shear strength mean value: 5 Primer composition Longitudinal tensile shear strength [N / mm2] Non-inventive: 6.5 without primer Inventive: 8.0 Primer A The longitudinal tensile shear tests of a further commercially available 1K-PUR adhesive in combination with Primer A according to the invention show that the primer compositions according to the invention are suitable not only for a specific adhesive quality, but in general for moisture-curing 1K-PUR adhesives. 202300221 Foreign Filings 28 Example 13: Three-point bending test for determining the bending modulus of elasticity on test specimens made of a Miscanthus material in accordance with DIN EN 310 (1993) in conjunction with Primer A according to the invention Substrate: Miscanthus (Miscanthus giganteus) Primer: 0.5 g on 60 g of Miscanthus stem pieces Adhesive: 6.6 g of pMDI on 60 g of Miscanthus stem pieces Pressing pressure: 1.2 N / mm² Pressing time and temperature: 120 min at 90°C Primer composition Mean value of the modulus of Number of test elasticity [N / mm2] specimens Non-inventive: 8861 6 without primer Inventive: 12207 3 Primer A

Claims

202300221 Foreign Filings 29 Claims 1. Adhesive system for the production of lignocellulosic composite materials, comprising a) a primer composition b) a moisture-curing 1-component polyurethane adhesive composition where the primer composition comprises: - 5-100% by weight of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function - 0-15% by weight of surfactants - 0-95% by weight of solvent.

2. Adhesive system according to Claim 1 for the production of lignocellulosic composite materials, comprising a) a primer composition b) a moisture-curing 1-component polyurethane adhesive composition where the primer composition comprises: - 50-100% by weight of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function - 0-15% by weight of surfactants - 0-50% by weight of solvent.

3. Adhesive system according to Claim 1 for the production of lignocellulosic composite materials, comprising a) a primer composition b) a moisture-curing 1-component polyurethane adhesive composition where the primer composition comprises: - 5-30% by weight of alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function - 0-15% by weight of surfactants - 55-95% by weight of solvent.

4. Adhesive systems according to Claim 1, characterized in that the alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function conform to the general formula (I)where the repeating units may be arranged in any desired order,202300221 Foreign Filings 30 with k + l = 1 – 10 and R1= independently identical or different H, R2, R3radicals, where R2= independently identical or different polyether radicals, preferably identical or different polyether radicals of the general formula where the repeating units may be arranged in any desired order, with a = 1–250, preferably 10 - 250, particularly preferably 10 - 100 b = 0–20, preferably 0 c = 0–20, preferably 0 d = 0–20, preferably 0 with the provisos a + b + c + d ≥ 5, a > b, a > c, a > d, R4= identical or different alkyl radicals that have 1 to 21 carbon atoms and optionally have ether functions, or aryl radicals that have 6-18 carbon atoms and optionally have ether functions, or H, preferably H, methyl, ethyl and phenyl and each R3radical = independently identical or different radicalscis configuration202300221 Foreign Filings 31 where the repeating units may be arranged in any desired order, with e = 1 - 21, preferably 13 - 17 f = 0 - 2, preferably 0 – 1 g = 0 - 3, preferably 0 - 1 h = 0 - 3, preferably 0 - 1 i = 0 - 2, preferably 0 - 1 j = 0 - 1, preferably 0 and where in (I) at least one of the independently identical or different R3radicals is present with g+h+i+j ≥ 1 and at least one R2radical is present.

5. Adhesive systems according to Claim 4, characterized in that the alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function are selected from the class of the glycerol esters and conform to the general formula (I) with k = 1 and l = 0.

6. Adhesive systems according to Claim 1, characterized in that the alkoxylated (poly)glycerol esters prepared from fatty acids which comprise at least one OH- and / or ether-function are produced by alkoxylation of castor oil or hydrogenated castor oil.

7. Adhesive systems according to Claim 1, characterized in that the surfactants are selected from the group of water-soluble surfactants, water-dispersible surfactants and mixtures thereof.

8. Adhesive systems according to Claim 1, characterized in that the solvent for the primer composition is preferably water.

9. Adhesive systems according to Claim 1, characterized in that the moisture-curing 1-component polyurethane adhesive composition is characterized in that - they contain prepolymers which are formed by reaction of polyether polyols and aromatic isocyanates having two or more NCO functionalities and - it has an NCO content of 1-28% by weight, preferably an NCO content of 1-20% by weight, particularly preferably an NCO content of 10-20% by weight.

10. Adhesive systems according to Claim 1, characterized in that the moisture-curing 1-component polyurethane adhesive composition is characterized in that it - contains polymeric diphenylmethane diisocyanate (pMDI) as main component and - it has an NCO content of 28 – 32% by weight.202300221 Foreign Filings 32 11. Adhesive system according to Claim 1, characterized in that the 1-component polyurethane adhesive composition contains crosslinkers, fillers, catalysts, stabilizers, defoamers, antioxidants, viscosity modifiers, activators, further auxiliaries and mixtures thereof.

12. Method for bonding with adhesive systems according to Claim 1-11, characterized by a) provision of at least two identical or different lignocellulosic materials, b) optionally: production of an aqueous primer composition by addition of water to a primer composition according to Claim 1 – 2 c) application of the aqueous primer composition according to Claim 1 – 3, d) optionally: intermediate storage of the primer-treated lignocellulosic materials for an exposure time, e) application of the 1-component polyurethane adhesive composition to at least one lignocellulosic material, f) bringing together of the at least two lignocellulosic materials, g) compression of the lignocellulosic materials, h) optionally: post-curing of the bonded lignocellulosic materials by way of storage.

13. Use of the adhesive systems according to Claim 1-11 for the bonding of lignocellulosic materials.

14. Use of the adhesive systems according to Claim 13 for the bonding of hardwoods, softwoods, grasses, beech woods, oak woods, sweet chestnut and other Fagaceae, ash and other Oleaceae, birch and other Betulaceae, eucalypts, robinia, bangkirai, teak, meranti, ekki, merbau, abachi, wenge and other tropical timbers, Salicaceae, Douglas fir, pines, larches and other Pinaceae, hinoki cypress, Chinese fir, Japanese cedar and other Cupressaceae, acetylated wood, bamboo, Miscanthus, rice straw, cereal straw and hemp shives.

15. Use of the adhesive systems according to Claim 13 in bondings of sawn timber, fibres, chips, boards, wood splints, veneer, parquet, cross-laminated timber, glue-laminated timber, laminated veneer lumber, solid wood boards, veneer plywood, I-joists, TJI joists, scrimber products and shavings in furniture manufacture, structural glued laminated timber construction, boat construction, vehicles, facades.

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