NO327063B1 - Fiber-containing adhesive composition, process for its preparation, composite, and use thereof. - Google Patents

Abstract

Adhesive composition contains urethane prepolymer with specified urea content and fibrous filler. Adhesive composition contains up to 99.9 wt.% prepolymer (I) with urethane groups and a urea content of 0.05-1 wt.% (calculated as NH-CO-NH), 0.1-20 wt.% fibrous filler, 0-20 wt.% usual additives and 0-10 wt.% activator. (I) is derived from component A containing (A1) diol(s) and/or polyol(s), (A2) organic compound(s) containing primary and/or secondary amino groups and/or water and optionally (A3) other compound(s) with functional groups capable of an addition reaction with isocyanate groups and component B containing compound(s) with polyisocyanate groups. Independent claims are also included for: (a) the production of an adhesive composition by bringing the components into contact with one another; (b) composites, comprising substrate(s) and the adhesive composition; (c) above-ground, underground, ship, vehicle or aircraft structures containing the adhesive composition or composite.

Description

The invention relates to an adhesive composition, a method for producing this, a composite containing the adhesive composition, as well as the use of the adhesive composition or the composite in construction technology, ship, vehicle or ship building.

Wood is a recognized and proven material for the construction of buildings. For carrying out larger spans than is permitted by a single cut beam, laminated timber is used. Plank plywood is produced industrially by full-surface gluing of individual plank slats. With glued connections of short wooden slats in the longitudinal direction, the so-called wedge comb connection (Keilzinkenverbindung), it is possible to produce practically infinitely long single slats that are cut to the required size that the building part must have. In addition to larger dimensions, the gluing leads to a refinement of the natural material wood, because naturally occurring defects such as branches are cut out and the contraction and swelling of the wood due to climate changes is significantly reduced.

For such purposes, adhesive compositions which are mainly based on phenol/resorcinol resins or melamine/urea resins are usually used.

The adhesive systems predominantly used today are amino and phenol plasters which harden in a polycondensation reaction to the finished adhesive joint. The chemical curing reaction for these systems, which predominantly exist as two components, is started by mixing glue and hardener into glue mass. In the case of amino plastic types, curing initiation takes place in most cases by lowering the pH value, and in the case of phenolic plastic types by adding formaldehyde or paraformaldehyde. Even in the finished glue joint, free formaldehyde is still present in small quantities and can be released into the ambient air over a long period of time. However, it is suspected that formaldehyde can cause health damage.

From DE-A-4 412 759, a formaldehyde-free adhesive composition based on an isocyanate ratio polyurethane prepolymer is known. This adhesive composition particularly exhibits a viscosity that is not suitable for processing and a practically unacceptable pressing time. The viscosity is particularly important for pumpability and the ability of the adhesive composition to penetrate the substrate to be adhered (adhesion).

From the older application EP-A-1 072 621, adhesive compositions are known which contain a polyurethane prepolymer with isocyanate groups and fibers as fillers. There is, however, no concrete teaching regarding a urea group content.

The task according to the invention is to make available an adhesive composition which does not exhibit any formaldehyde emissions.

Furthermore, it is a task according to the invention that the adhesive composition made available exhibits good pumpability and workability, especially a suitable viscosity. When it comes to the processing, a further task in particular consists in that during the plank layer three-gluing, the adhesive composition is allowed to be carried on in elongated designs, especially cords, through application devices, which in most cases are in the form of a nozzle, on the surface of the wooden plank. Here it is of particular importance that the application takes place in a reproducible and pulsation-free manner and preferably particularly uniformly, as is preferably possible with a plant described in the journal "Holzzentralblatt", 11 October 1996.

A further task according to the invention lies in improving the storage stability of adhesive compositions which are based on polyurethane polymers.

In addition, a task according to the invention is that the adhesive composition can be used as a one-component system.

In addition, a task consists in ensuring that the adhesive compositions that are available according to the invention at least satisfy the above all in high and deep construction requirements that are particularly set by state testing institutes, and are at least as satisfactory as the adhesive compositions currently used, especially those that are based on phenol/resorcinol or melamine/urea resins, in comparable applications.

The tasks stated above are solved using an adhesive composition which - calculated on the weight of the composition - as components contains at least: - up to 99.9% by weight of a prepolymer with urethane groups and with a urea content of 0.05 to 1% by weight (calculated as NH-CO-NH, U = 58 g/mol), derived from component A,

content

A1) at least one diol or polyol,

A2) an organic compound bearing at least one primary and/or secondary amino group or water, and optionally

A3) additional compounds with functional groups capable of

react with icocyanate groups in an addition reaction,

component B,

content

at least one compound bearing polyisocyanate groups,

- 0.1 to 20% by weight of at least one filler containing fiber,

- 0 to 20% by weight of common additives and auxiliaries, as well as

- 0 to 10% by weight of an activator.

According to the invention, it is preferred that the adhesive composition exhibits in the range from 70 to 99, preferably 80 to 94 and especially preferred 85 to 90% by weight of the prepolymer and 1 to 17, preferably 5 to 17 and especially preferred 6 to 15% by weight of the filler which contains at least one fiber, as well as 0 to 5, preferably 0.01 to 3 and particularly preferred 0.01 to 1% by weight of the activator and possibly up to 20% by weight of further additives and auxiliaries, in each case calculated on the adhesive composition.

Furthermore, at least one of the following main characteristics (i) to (iii) is preferred for the adhesive composition according to the invention: (i) the prepolymer exhibits at least one of the following sub-characteristics (a) and (b): (a) an NCO content of 5 to 30% by weight, calculated on the prepolymer,

(b) a viscosity at 25°C in the range of 300 to 150,000 mPa-s,

(ii) component A exhibits at least one of the following sub-characteristics (c) and (d): (c) in the case of component A, it is water, monoamines with a primary or secondary amino group, diamines with primary and/or secondary amino groups or amino alcohols with a primary or secondary amino group,

(d) the OH number of component A is in the range from 10 to 500 mg KOH/g,

(iii) the filler exhibits at least one of the following subcharacteristics (e) or (f):

(e) the fibers consist of at least one fibrous polymer,

(f) the filler consists in addition to the fibers of at least one filler that is not fibrous.

Furthermore, the present invention comprises a method for producing an adhesive composition according to one of claims 1 to 6, where the components defined in claim 1 are brought into contact with each other.

Adhesive composition according to the invention described in the foregoing is also included where it exhibits at least one of the following material properties (g) to (m): (g) drying time in normal climate 20/65-1 according to DIN 50014 at an applied

quantity of 250 g/m<2> in the range from 20 to 40 minutes,

(h) drying time in normal climate 20/65-1 according to DIN 50014 with an applied

quantity of 400 g/m<2> in the range from 20 to 40 minutes,

(i) viscosity at 25°C in the range from 300 to 150,000 mPa-s,

(k) storage stability from 1 to 4 months,

(I) NCO content in the range from 3 to 20% by weight, calculated on the adhesive composition,

(m) minimum pressing time according to DIN 68141 in the range from 5 to 8 hours.

A composite which at least contains a substrate and an adhesive composition as described above is also covered by the invention.

The present invention comprises the use of a

adhesive composition or a composite as described above in building, underground, ship, vehicle or aircraft construction.

Building, underground, ship, vehicle or aircraft construction which exhibits an adhesive composition or a composite as described above is also covered by the invention.

The viscosity of the prepolymer at 25°C is preferably in a range between 300 and 15,000, preferably between 100 and 10,000 mPa-s, if the adhesive composition is to be pumpable. If, on the other hand, the intention is to use the adhesive composition as a pasty mass to be applied with a trowel, the viscosity of the prepolymer at 25°C is preferably in the range of 15,000 to 150,000 and particularly preferably in the range of 20,000 to 100,000 mPa-s.

The urea content is preferably 0.1 to 0.5% by weight, particularly preferably 0.15 to 0.3% by weight.

The urea group can be introduced in a manner known per se into the polyurethane prepolymer.

Furthermore, according to the invention, it is preferred that the adhesive composition contains little solvent. This is the case if the amount of solvent that the adhesive composition contains is less than 10, preferably less than 5 and particularly preferably less than 2% by weight. Solvents according to the invention are organic and inorganic liquids which are suitable as carriers for the additional components in the adhesive composition and do not harden with at least part of the other components.

In an embodiment according to the invention of the adhesive composition, both the aforementioned main characteristic for the prepolymer (i) and also the main characteristic (ii) for component A are realised.

In another embodiment according to the invention of the adhesive composition, the main characteristic (ii) for component A as well as the main characteristic for the filler (iii) are fulfilled.

In another embodiment according to the invention of the adhesive composition, all three main characteristics (i) to (iii) are fulfilled.

Preferred embodiments of the adhesive composition are those where the prepolymer, component A and the filler in each case fulfill both subcharacteristics (a) and (b), respectively. (c) and (d), respectively. (e) and (f).

In another preferred embodiment according to the invention of the adhesive composition, all main characteristics (i) to (iii) as well as all sub-characteristics (a) to (f) are fulfilled.

It is preferred that the fiber polymers in the prepolymer are predominantly made up of organic or inorganic materials.

As organic materials for fiber polymers, polycondensates and polyaddition products come into consideration and which are preferably not polyurethane, with polycondensates being preferred. As polycondensates, polycarbonates, polyesters, polyamides, polyimides, melamine-formaldehyde resins are particularly suitable.

Polyaddition polymers are in particular polyacrylates, polymethacrylates, polystyrenes, polyacrylates, polyethylene, polypropylene, polyvinyl alcohol, as well as the copolymers of at least two monomers of the aforementioned homopolymers, as well as mixtures of at least two of these.

In the adhesive composition according to the invention, it is particularly preferred that a polyamide is used as fiber polymer. For this purpose, all commercially available polyamides known to those skilled in the art are suitable. In particular, however, polyamides such as nylon, especially nylon-6,6 or nylon-6, as well as polyaramids have proven to be suitable.

Furthermore, the fibers can consist of or be based on natural, organic fiber polymers, for example cellulose, cotton, jute and sisal, as well as viscose. In addition, the fibers can also be formed from inorganic materials.

Carbon, glass and mineral wool fibers are preferred as inorganic fiber polymers. Furthermore, it is possible that the fibers are obtained from different materials, for example by spinning.

The fibers used according to the invention preferably have a diameter in the range from 5 to 100, preferably 10 to 60 and particularly preferred 10 to 30 µm, and a length in the range from 0.02 to 6, preferably 0.05 to 4 and particularly preferred 0.1 to 2 mm.

In addition, the adhesive compositions according to the invention can have a filler body consisting of at least one inorganic material. In principle, all inorganic materials known to the person skilled in the art and especially the inorganic materials which can be purchased are suitable for the adhesive according to the invention, and which are available as a solid. The inorganic materials must, especially in the temperature range in which the adhesive composition according to the invention is processed and where the glued object is later to be used, be present as a solid substance. This temperature range preferably starts at -50 and extends to +130°C.

As particularly suitable inorganic materials, the oxygen compounds of silicon, aluminum or magnesium or mixtures of at least two of the mentioned oxygen compounds have been shown to be, and which in addition possibly exhibit further elements. Silicates and aluminum oxides are particularly suitable, for example clay types such as China clay and quartz compounds or silicic acid.

The non-fibrous filler bodies are preferably particulate. 80% of the particulate filler bodies have a particle size in the range from 0.01 to 50, preferably 0.1 to 10 and particularly preferably 0.2 to 8 (im.

The filler used according to the invention may contain fibers or additional filler bodies. If the filler exhibits both fibers and filler bodies, it is preferred that at least as much filler bodies as fibres, preferably filler bodies in excess, are to be found in the filler.

Fillers are especially contained in the adhesive compositions according to the invention to improve the physical properties for the various applications. For this purpose, after curing, the adhesive composition must form a blister-free adhesive layer that is as compact as possible, and the joints between the substrates must preferably be completely filled. To increase the adhesion, the adhesive composition should partially penetrate the substrate surface. However, after the adhesive composition has cured into adhesive, voids must not form due to this penetration or shrinkage which could impair the cohesion. Especially in thicker joints in the range from greater than 0.1 to 1 mm, preferably 0.2 to 1 mm, these requirements can be met particularly well by incorporating fillers with the previously described composition in the adhesive composition.

The activator in the adhesive composition according to the invention consists of at least one morpholine derivative. Particularly suitable as morpholine derivatives are 4-methylmorpholine, 4-ethylmorpholine, 4-cyclohexylmorpholine, 2,2'-dimorpholine diethyl ether or dimorpholine polyethylene glycol or mixtures of at least two of these morpholine derivatives. Furthermore, in addition to the morpholine derivative, further compounds that have an activating effect, such as those described for example as polyurethane catalysts in Becker/Braun, Kunst-stoffhandbuch 7 (1993), can be used, the proportion of the morpholine derivatives being preferably larger.

Especially when it comes to storage stability, auxiliaries that lead to thixotropy have proven to be beneficial. Particularly preferred thixotropy-giving aids are bentonites, kaolins, alginic acid and silicic acid, silicic acid being particularly preferred. In addition to or instead of the aforementioned thixotropy-giving aids which consist of solid bodies, soluble thixotropy-giving aids are preferred, and which can for example be obtained by reacting an icocyanate in the presence of amines, as described in EP-A-300 388, DD -A-156 480, DD-A-211 689, DD-A-211 930 and DD-A-211 931.

Furthermore, the adhesive composition according to the invention is preferably solvent-free.

As auxiliaries that provide thixotropic behavior, these are very fine particulate substances that thicken liquids when they are added in small quantities to the liquid, for example up to a maximum of 10% by weight, calculated on the liquid. Preferably, these small particles have silanol groups on their surface which interact with the liquid with which they are dispersed, forming hydrogen-bridge bonds, and thus lead to a thickening of this liquid. Typical of thixotroping aids is that for the same quantity, the thickening effect increases with decreasing particle size with appropriate careful dispersion and vigorous mixing. Furthermore, the thixotropy-giving aids have the advantage that they do not settle in the dispersed liquid. In addition, the thixotroping aids prevent or delay the sedimentation of fillers. As materials for thixotropy aids, preferred in fine powder form are montmorillonite, Mg/AI silicate, AI/Na silicate, bentonite, hectorite, Na/Mg silicate, pyrogenic silicic acids, hydrated silicic acids, hornblende-chrytosil, chrytosil-asbestos, chrytosil-silicic acid, as well as precipitated magnesium oxide, as pyrogenic silicic acids can for example be obtained as Aerosil from Degussa-Huls AG and Mg silicates which can be obtained as Bentone from Kronos Titan GmbH Leverkusen, are preferred and Aerosil is particularly preferred.

The adhesive composition according to the invention is prepared by bringing the previously defined components into contact with each other. This preferably takes place in the presence of mixing devices, as dynamic as well as static, preferably dynamic, mixing devices can be used.

Preferably, the prepolymer according to the invention is obtained by placing component B, preferably a monomeric isocyanate, in a reactor and component A, preferably a suitable alcohol, is added with a mixing device in a temperature range between 20 and 120, preferably 40 to 100 and especially preferably 60 to 90°C.

The components are preferably mixed with each other using the mixing device so thoroughly that an adhesive composition is obtained from the components which is as homogeneous as possible.

The adhesive composition according to the invention exhibits at least one of the following material properties (g) to (m): (g) Drying time in normal climate 20/65-1 according to DIN 68141 at an applied amount of 250 g/m<2> in the range from 20 to 40, preferably 30 to 50 and esp

preferably 40 to 80 minutes,

(h) drying time at normal climate 20/65-1 according to DIN 68141 at an applied amount of 400 g/m<2> in the range from 20 to 40, preferably 30 to 60 and especially

preferably 40 to 100 minutes,

(i) viscosity at 25°C in the range from 300 to 150,000 mPa s,

(k) storage stability from 1 to 4, preferably from 2 to 6 and particularly preferred 3 to 8

months,

(I) NCO content in the range from 3 to 20, preferably 5 to 17 and particularly preferred

from 6 to 15% by weight, calculated on the adhesive composition,

(m) minimum pressing time according to DIN 68141 in the range from 5 to 8, preferably 4 to 6 and especially 2 to 4 hours.

Preferably, the viscosity is at 25°C for the adhesive composition

in a range from 300 to 15,000, preferably 500 to 10,000 mPa-s, for pumpable adhesive compositions. If, on the other hand, it is intended that the adhesive composition should have a pasty composition which is suitable for

sparkling, the viscosity at 25°C of the adhesive composition is preferably in a range from 15,000 to 150,000 and particularly preferably 20,000 to 100,000 mPa-s.

The storage stability of the adhesive composition is determined by the sedimentation behavior of the fillers. Storage stability exists according to the invention if the phase separation is followed over time in a container which is completely filled with adhesive and which is moisture-proof, as well as airtight and closed over a given period of time and the lowering of the phase boundary (deposition of fillers) is less than 5%, calculated on the initial fill height.

A preferred embodiment of the adhesive composition according to the invention exhibits, based on the aforementioned characteristics, at least the viscosity (i) and the storage stability (k).

Another preferred embodiment of the adhesive composition according to the invention exhibits, of the aforementioned characteristics, at least the viscosity (i) and the storage stability (k), as well as the minimum pressing time (m).

In addition, one embodiment of the adhesive composition according to the invention exhibits the aforementioned material properties at least the viscosity (i), the storage stability (k) and the NCO content (I).

Furthermore, one embodiment of the adhesive composition according to the invention of the aforementioned material properties exhibits at least the viscosity (i), the storage stability (k) and the NCO content (I), as well as the minimum pressing time (m).

Another preferred embodiment of the adhesive composition exhibits all of the aforementioned material properties (g) to (m).

Furthermore, the invention relates to a composite which contains at least a substrate and an adhesive composition according to the invention. The substrate is preferably a cellulose-containing material. As cellulose-containing materials, all naturally occurring and artificially made materials known to the person skilled in the art come into consideration. As naturally occurring materials, particular mention should be made of types of wood from different trees, for example conifer type r or hardwood types. Artificial, cellulose-containing materials are, for example, types of paper, cardboard, laminates, pressed chipboard and the like. As substrates, materials which can be glued in a similar way to the cellulose-containing materials with the adhesive composition according to the invention also come into consideration.

A preferred composite is endless wooden planks consisting of at least two connected to each other over the end pieces - e.g. over a wedge comb connection - single planks, the wedge combs being connected by means of the adhesive composition according to the invention.

A further preferred composite according to the invention is laminated wood which consists of a large number of surface-glued individual planks, where the planks are connected to each other at least partially, preferably completely, by means of the adhesive composition according to the invention. Instead of single planks, endless wooden planks can also be used.

Further preferred is a composite where the substrate contains wood and is layer- and/or wedge-comb glued.

The adhesive composition according to the invention is particularly suitable for the production of plank layer wood types.

The composites according to the invention are also suitable for use as a load-bearing component in roof, bridge and wall constructions and likewise for the production of concrete formwork, especially as concrete formwork carriers, as well as in scaffold construction, especially as scaffold covering.

Furthermore, it is preferred that the composite according to the invention exhibits at least one of the following material properties: (n) A delamination resistance according to DIN EN 302, part 2, of a maximum of 5% according to DIN EN 301, preferably a maximum of 3% and particularly preferred

maximum 1%,

(o) a dry shear strength in the range from at least 6 N/mm<2> up to maximum substrate failure according to the quality guidelines of the RAL-Gutergemeinschaft Holzleimbau.

Substrate breaking and shear strength values for different types of wood can be found in Holzlexikon DRW-Verlag, 3rd edition 1988. Substrate breaking strength value for the type of wood usually used for plywood is approx. 7.5 N/mm<2>.

In the production of the prepolymer for the adhesive composition according to the invention, components A and B are preferably used in such a ratio that the result is the previously described properties for the prepolymer, especially the NCO content, the urea content and the viscosity. In addition, auxiliaries and additives or catalysts can be used for the production of the prepolymer.

The additional starting materials or components for the production of prepolymer and adhesive compounds shall be described in the following for example: As diols or polyols (component A1), those with a functionality from 2 to 8, preferably 2 to 6, and a molecular weight from 62 can be suitably used to 10,000. As suitable, e.g. polyols selected from the group of polyether polyols proved to be, for example polytetrahydrofuran or polypropylene oxide, as well as polyesterols, polythioether polyols, hydroxyl group-containing polyacetals and hydroxyl group-containing aliphatic polycarbonates or mixtures of at least two of the aforementioned polyols. Polyester polyols and/or polyether polyols are preferably used. The hydroxyl number of the polyhydroxyl compounds is usually 20 to 850 mg KOH/g and preferably 25 to 500 mg KOH/g.

As components, possibly diols and/or triols with molecular weights from 62 to over 400 can be used as chain extenders and/or cross-linking agents in the method according to the invention. For modification of the mechanical properties, e.g. the hardness, and for increasing the stability of the prepolymer, however, the addition of chain extenders, cross-linking agents and possibly also mixtures of these may prove to be advantageous. The chain extenders and/or crosslinkers preferably have a molecular weight of from 62 to 300 g/mol. For example, aliphatic, cycloaliphatic and/or araliphatic diols with 2 to 14, preferably 4 to 10, carbon atoms, e.g. ethylene glycol, propanediol-1,3, decanediol-1,10, o-, m-, p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol, and preferably butanediol-1,4, hexanediol-1,6 and bis-(2-hydroxy-ethyl )-hydroquinone, triols, such as 1,2,4-, 1,3,5-hydroxycyclohexane, glycerol and trimethylolpropane and low molecular weight hydroxyl group-containing polyalkylene oxides based on ethylene and/or 1,2-propylene oxide and the aforementioned diols and /or triols as starter molecules.

As polyol components, high-functional polyols, especially polyetherols based on high-functional alcohols, sugar alcohols and/or saccharides can generally also be used as starter molecules. Preferably, however, 2- and/or 3-functional polyether or polyester alcohols based on glycerol and/or trimethylolpropane and/or glycols are used as starter molecules, respectively. as alcohols to be preferred. The production of the polyetherols thereby takes place according to known technology. Suitable alkylene oxides for the production of the polyols are, for example, tetrahydrofuran, ethylene oxide, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide, styrene oxide, preferably ethylene oxide and 1,2-propylene oxide. The alkylene oxides can be used individually, alternately one after the other or as mixtures. Particularly preferably used in the prepolymer in the adhesive composition according to the invention are polyetherols such as those which, at the end of the alkoxylation, were alkoxylated with ethylene oxide and thus exhibit primary hydroxyl groups.

As starter molecules come into consideration, for example: Water, glycols, such as ethylene glycol, propylene glycol, 1,4-butanediol and 1,6-hexanediol, amines, such as ethylenediamine, hexamethylenediamine, and 4,4-diamino-diphenylmethane and amino alcohols, such as ethanolamine or triethanolamine.

The polyether alcohols have a functionality of preferably 2 to 6 and especially 2 to 3, and molecular weights from 400 to 10,000, preferably 1,000 to 7,000. The polyetherols can be used alone or in mixtures.

Polycarbonate diols are also suitable. As polycarbonate diols, those with aromatic dihydroxy compounds come into consideration, e.g. based on 4,4'-dihydroxydiphenyl-2,2-propane or those based on aliphatic dihydroxy compounds, e.g. 1,6-hexanediol. The molecular masses are in the range from 500 to 4,000, preferably from 1,000 to 2,000.

Suitable polyesterols as a polyol component can for example be produced from organic dicarboxylic acids with 2 to 12 carbon atoms, preferably aliphatic dicarboxylic acids with 4 to 6 carbon atoms, and polyhydric alcohols, preferably diols, with 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, by polymerization of lactones with 3 to 20 C atoms. As dicarboxylic acids, it can e.g. glutaric acid, pimelic acid, corkic acid, sebacic acid, dodecanoic acid and preferably adipic acid, succinic acid and phthalic acid are used. The dicarboxylic acids can be used individually or as mixtures. For the production of the polyester polyols, it may possibly be advantageous to use the corresponding acid derivatives such as carboxylic acid anhydrides or carboxylic acid chlorides instead of the dicarboxylic acids. Suitable aromatic dicarboxylic acids are terephthalic acid, isophthalic acid, phthalic acid or mixtures of these with other dicarboxylic acids, e.g. diphenic acid, sebacic acid, succinic acid and adipic acid. Examples of suitable glycols are diethylene glycol, 1,5-pentanediol, 1,10-decanediol and 2,2,4-trimethylpentanediol-1,5. 1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol and 2,2-dimethylpropanediol-1,3 are preferably used; 1,4-dimethylolcyclohexane; 1,4-diethanolcyclohexane, ethoxylated/propoxylated products of 2,2-bis-(4-hydroxyphenyl)-propane (Bisphenol A). Depending on the desired properties of the polyurethanes, the polyols can be used alone or as a mixture in different proportions. As lactones for the production of the polyesterols, e.g. alpha, alpha-dimethyl-beta-propiolactone, gamma-butyrolactone and preferably epsilon-caprolactone. The polyesterols preferably have a functionality of 2 to 4, especially 2 to 3, and a molecular weight of 1,200 to 3,000, preferably 1,500 to 3,000 and especially 1,500 to 2,500.

According to the invention, especially polyol mixtures are suitable for the prepolymer. Such polyol mixtures preferably have one diol, preferably polypropylene glycol, and at least one triol, preferably polyethertriol. Particularly suitable diols have an average molecular weight in the range of 500 to 3,000, preferably 700 to 1,500 and particularly preferred 800 to 1,500 and particularly preferred 800 to 1,200. As triols, those with an average molecular weight of 1,000 to 8,000, preferably 2,000 to 6,000 and particularly preferably 3,000 to 5,000, proved to be suitable. It is particularly preferred that the polyol mixture exhibits an OH number in the range from 30 to 140, preferably 50 to 90 and particularly preferably 60 to 80 mg KOH/g. The diols and triols mentioned above can not only be used as a polyol mixture, but also individually for the preparation of the prepolymer.

In another embodiment of the prepolymer according to the invention, the use of a polyether polyol which preferably exhibits primary hydroxyl groups with an OH number in the range from 10 to 60, preferably 20 to 40 and particularly preferably 25 to 35 mg KOH/g, has been shown to be suitable.

If chain extenders, cross-linking agents or mixtures of such are used for the production of the prepolymers, it is appropriate to use these in an amount of 0 to 20% by weight, preferably 0.5 to 5% by weight, calculated on the weight of the total used against isocyanates reactive connections.

As regards the components A2, it is preferably those which are listed above under characteristic (c). In a preferred embodiment, the urea groups are introduced while adding water. Thereby arises according to the equation

2 RNCO + H2O -> RNH-CO-NHR + CO2

from 1 mol of water 1 mol of urea.

In a particularly preferred embodiment, the water is introduced by means of the fillers. For this purpose, the fillers are either dried to a certain residual water content or - if the residual water content is not sufficient - moistened.

The residual water content W (in percent) to be set can be calculated according to the equation: W = U* 1800/(2*58)

Here means:

W residual water content in percentage to be set

U desired content of urea in percent

Z content of aggregates in the adhesive preparation in percent

If the urea groups are introduced by adding amines or water, the amount of water that has been brought in through the fillers must in all cases be taken into account.

If a mixture of fillers is used, it does not matter whether the water is essentially introduced through one of the fillers or through several of these.

Component A3 usually involves other compounds with functional groups capable of reacting with the isocyanate groups n in an addition reaction. Such compounds are present, calculated on the total amount of component A, usually in an amount up to 20% by weight. This concerns, for example, mercaptans or monoalcohols which are used to limit the molecular weight.

As isocyanates or polyisocyanates in component B, the per se known aliphatic, cycloaliphatic, araliphatic and/or aromatic isocyanates, preferably diisocyanates, can be used, and which may optionally be biuretized and/or isocyanuratized according to generally known methods. Examples should be mentioned in detail: Alkylene diisocyanates with 4 to 12 carbon atoms with an alkylene residue, such as 1,12-dodecane diisocyanate, 2-ethyltetramethylene diisocyanate-1,4, 2-methylpentamethylene diisocyanate-1,5, tetramethyl diisocyanate-1,4, lysine ester diisocyanate ( LDI), hexamethylene diisocyanate-1,6 (HDI), cyclohexane-1,3- and/or -1,4-diisocyanate, 2,4- and 2,6-hexahydrotoluenediisocyanate, as well as the corresponding isomeric mixtures, 4,4' -, 2,2'- and 2,4'-dicyclohexylmethane diisocyanate, as well as the corresponding isomer mixtures, 1 -isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,4- and/or 2, 6-Toluylene diisocyanate, 4,4'-, 2,4'- and/or 2,2'-diphenylmethane diisocyanate (monomeric MDI), polyphenylpolymethylene polyisocyanates (polymer MDI), and/or mixtures containing at least two of the aforementioned isocyanates . In addition, di- and/or polyisocyanates containing ester, allophanate, carbodiimide, uretdione and/or urethane groups can be used in the method according to the invention.

According to the invention, particularly preferred for the production of the prepolymer in the adhesive composition according to the invention is MDI, such as polymer MDI or preferably monomer MDI, especially 4,4'-MDI, or mixtures of 2,4'-MDI and 4,4' - MDI.

In one embodiment according to the invention, it has been found to be particularly suitable for the prepolymer to use a polymer MDI with an average functionality in the range of 1 to 5, preferably 1.5 to 4 and particularly preferably 2 to 3.5, and a viscosity in the range 100 to 400, preferably 150 to 300 and particularly preferably 160 to 260 mPa-s.

As catalysts, generally known compounds can be used, compounds which greatly speed up the reaction of isocyanates with compounds reactive to isocyanates, with a total catalyst content of 0.01 to 8% by weight, especially 0.1 to 5% by weight, calculated on the weight of the compounds used in total which are reactive towards isocyanates are preferably used. For example, the following compounds can be used: Triethylamine, tributylamine, dimethylbenzylamine, dicyclohexylmethylamine, dimethylcyclohexylamine, N,N,N',N,-tetramethyldiamino-diethylether, bis-(dimethylaminopropyl)-urea, N-methyl- or N-ethylmorpholine, N ,N'-dimorpholino-diethylether (DMDEE), N-cyclohexylmorpholine, N,N,N',N,-tetramethylethylenediamine, N,N,N',N,-tetramethylbutanediamine, N,N,N<l>,N< l->tetramethylhexanediamine-1,6, penta-methyldiethylenetriamine, dimethylpiperazine, N-dimethylaminoethylpiperidine, 1,2-dimethylimidazole, N-hydroxypropylimidazole, 1-azabicyclo-(2,2,0)-octane, 1,4-diazabicyclo -(2,2,2)-octane (Dabco) and alkanolamine compounds, such as triethanolamine, triiso-propanolamine, N-methyl- and N-ethyl-diethanolamine, dimethylaminoethanol, 2-(N,N-dimethylaminoethoxy)ethanol, N,N',N-tris-(dialkylaminoalkyl)hexahydrotriazine, e.g. N,N',N-tris-(dimethylaminopropyl)-s-hexahydrotriazine, iron (II) chloride, zinc chloride, lead octoate and preferably tin salts, such as tin dioctoate, tin diethylhexoate and/or dibutyl tin dilaurate, 2,3-dimethyl-3, 4,5,6-tetrahydropyrimidine, tetraalkylammonium hydroxide, such as tetramethylammonium hydroxide, alkali hydroxides, such as sodium hydroxide, alkali alcoholates, such as sodium methylate and potassium isopropylate and/or alkali salts of long-chain fatty acids with 10 to 20 C atoms and optionally adjacent OH groups. Mention should also be made of trimerization catalysts such as alkali or alkaline earth acetate, preferably potassium acetate. The above-mentioned catalysts can also additionally be used as activators for the morpholine derivatives used as activators. Thus, catalysts are incorporated into the prepolymer as such during its production and activators with the prepolymer as an additional component incorporated into the adhesive composition according to the invention. As catalysts or activators, further has Ti compounds, especially Ti(IV)-0-alkyl compounds with alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl , preferably ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl and particularly preferred Ti(IV)-butylate, proved to be suitable.

Further auxiliaries and/or additives may optionally be added to the reaction mixture for the production of the prepolymers. It must e.g. mention are made of surface-active substances, stabilizers, cell regulators, fillers, dyes, pigments, flame retardants, hydrolysis inhibitors, substances that have a fungistatic and bacteriostatic effect. The surface-active substances and stabilizers counteract a "skin formation" on the surface of the adhesive composition that faces air. Furthermore, the surface-active substances and the stabilizers improve the drainage of the adhesive composition, as well as the creep ability of the adhesive composition and the degassing thereof. As surface-active substances, e.g. compounds in consideration which serve to support the homogenisation of the starting materials. Examples include emulsifiers such as the sodium salts of castor oil sulphates or of fatty acids, as well as salts of fatty acids with amines, e.g. oleic acid diethylamine, stearic acid diethanolamine, ricinol acid diethanolamine, salts of sulphonic acids, e.g. alkali or ammonium salts of dodecylbenzene or dinaphthylmethanesulfonic acid and ricinolic acid; stabilizers such as siloxane-oxalkylene blend polymers and other organopolysiloxanes, oxytylated alkylphenols, oxytylated fatty alcohols, paraffin oils, castor oil or ricinoleic acid esters, Turkish red oil and peanut oil, and cell regulators such as paraffins, fatty alcohols and dimethylpolysiloxanes. For improving the emulsifying effect, the cell structure and/or the stabilization of the prepolymer, the above-described oligomeric acrylates with polyoxyalkylene and fluoroalkane residues as side groups are also suitable. If foaming is to be reduced or avoided, trialkyl phosphates are preferred as antifoams. These preferably have alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, preferably ethyl, n-propyl, isopropyl, n-butyl, isobutyl , tert-butyl. Tributyl phosphate, available under the trade name defoamer T (Entschåumer T) from Bayer AG, is particularly preferred for the aforementioned purpose. The surface-active substances are usually used in amounts of 0.01 to 5% by weight, calculated on 100% by weight of the total used and isocyanate-reactive compounds. Fillers, in particular fillers that have a reinforcing effect and that the prepolymer may contain independently of those in the actual adhesive composition, are to be understood as the usual organic and inorganic fillers known per se, reinforcing agents, weighting agents, agents for improving the wear ratio, layer-forming agents, etc. The following exemplary listing applies to the prepolymer as well as to the adhesive composition according to the invention. For example, the following should be mentioned in detail: Inorganic fillers or fillers, such as silicate minerals, for example layer silicates such as antogorite, serpentine, hornblende, amphiboles, chrystotile and talc, metal oxides, such as kaolin, aluminum oxides, titanium oxides and iron oxides, metal salts such as chalk, tungspar and inorganic pigments, such as cadmium sulphide and zinc sulphide, as well as glass, etc. Kaolin (China clay), aluminum silicate, montmorillonite and co-precipitates of barium sulphate and aluminum silicate are preferably used, as well as natural and synthetic fibrous minerals, such as wollastonite, metal and especially glass fibers of different lengths which may be smoothed. Examples of organic fillers that come into consideration are: Charcoal, melamine, rosin, cyclopentadienyl resins and cork polymers. The inorganic and organic fillers can be used individually or as mixtures, and are added to the reaction mixture with advantage in amounts of 0.5 to 50% by weight, preferably 1 to 40% by weight, calculated on the weight of the isocyanates and the weight of the isocyanate-reactive compounds used in general .

The previously indicated fillers can be incorporated individually with the prepolymer or already as a component of the prepolymer or both with and also as a component of the prepolymer in the adhesive composition according to the invention.

Suitable flame retardants are, for example, tricresyl phosphate, tris-(2-chloroethyl)-phosphate, tris-(2-chloropropyl)-phosphate, tris-(1,3-dichloropropyl)-phosphate, tris-(2,3-dibromopropyl)- phosphate, tetrakis-(2-chloroethyl)-ethylenediphosphate, dimethylmethanephosphonate, di-ethanolaminomethylphosphonic acid diethyl esters, as well as halogen-containing flame retardant polyols of the usual commercial type. In addition to the already mentioned halogen-substituted phosphates, inorganic or organic flame retardants such as red phosphorus, aluminum oxide hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium phosphate, swelling graphite or cyanuric acid derivatives, such as e.g. melamine, or mixtures of at least two flame retardants such as e.g. ammonium polyphosphates and melamine, as well as any corn starch or ammonium polyphosphate, melamine and swelling graphite and/or possibly aromatic polyesters are used to increase the flame resistance of the prepolymer, respectively. the adhesive composition. In general, it has proven to be appropriate to use 5 to 50% by weight, preferably 5 to 25% by weight, of the mentioned flame retardants, calculated on the weight of the total compounds reactive to isocyanates used.

An adhesive composition according to the invention or a composite according to the invention, preferably in laminated wood, can be used in building, underground, ship, vehicle or aircraft construction, preferably in high or deep construction.

Furthermore, the invention relates to building, underground, ship, vehicle or aircraft constructions, preferably in laminated wood which exhibits an adhesive composition or a composite or both.

The invention will now be explained based on examples.

Example 1

In a piping container, 59.4 kg of a 50/50 mixture of 2,4'- and 4,4'-diphenylmethane diisocyanate was placed and heated with stirring at 80°C. To this was slowly added 40.6 kg of a mixture of a polypropylene oxide diol with a molecular weight of 1,000 g/mol and a polypropylene oxide triol with a molecular weight of 4,000 g/mol. The polyol mixture had an OH number of 73 mg KOH/g.

After completion of the addition, it was stirred for 60 minutes, cooled to 25°C and filled off.

In a container equipped with a dissolution disc, 87.4 kg of the prepolymer was placed. To this, it was successively added with a continuous dissolving device

This corresponds to a water quantity of 66 g, from which a urea content of 0.213% by weight is calculated.

Even after storage for six months, the preparation shows no sedimentation, and is still able to flow completely.

Comparative example 1

The experiment from the example was repeated, but with fillers that had been dried to a water content of <0.1%. This corresponds to a maximum water quantity of 12.5 g A

40.278 g urea 4 0.040 wt% urea. The preparation had already settled after a week.

Comparative example 2

The experiment from the example was repeated, but with fillers that had been dried to a water content of 2.5%. This corresponds to a quantity of water of 312.5 g 4 1,007 g urea A 1.01 wt% urea. After just one week, the preparation was no longer able to flow.

Claims (13)

1. Adhesive composition, characterized in that it - calculated on the weight of the composition - as components contains at least - up to 99.9% by weight of a prepolymer with urethane groups and with a urea content of 0.05 to 1% by weight (calculated as NH-CO-NH, U = 58 g/mol), derived from component A, content A1) at least one diol or polyol, A2) an organic compound bearing at least one primary and/or secondary there amino group or water, and optionally A3) additional compounds with functional groups capable of react with icocyanate groups in an addition reaction, component B, content at least one compound bearing polyisocyanate groups, - 0.1 to 20% by weight of at least one filler containing fibres, - 0 to 20% by weight of usual additives and auxiliaries, and - 0 to 10% by weight of an activator. 2. Adhesive composition according to claim 1, characterized in that it has at least one of the following characteristics (i) to (iii): (i) the prepolymer exhibits at least one of the following sub-characteristics (a) and (b): (a) an NCO content of 5 to 30 by weight %, calculated on the prepolymer, (b) a viscosity at 25°C in the range from 300 to 150,000 mPa-s, (ii) component A exhibits at least one of the following sub-characteristics (c) and (d): (c) when in the case of component A, it concerns water, monoamines with a primary or secondary amino group, diamines with primary and/or secondary amino groups or amino alcohols with a primary or secondary amino group, (d) the OH number for component A is in the range from 10 to 500 mg KOH/g, (iii) the filler exhibits at least one of the following sub-characteristics (e) or (f): (e) the fibers consist of at least one fiber polymer, (f) the filler consists in addition to the fibers of at least one filler which is not fibrous. 3. Adhesive composition according to claim 2, characterized in that it has at least one of the characteristics (iv) and (v): (iv) the fiber polymer is at least one polyamide, (v) the filler body consists of at least one inorganic material. 4. Adhesive composition according to claim 3, characterized in that the inorganic material is an oxygen compound of silicon, aluminum or magnesium, or mixtures of at least two of the aforementioned oxygen compounds. 5. Adhesive composition according to one of claims 1 to 4, characterized in that the activator consists of at least one morpholine derivative. 6. Adhesive composition according to one of claims 1 to 5, characterized in that the adhesive composition contains little solvent. 7. Method for producing an adhesive composition according to one of claims 1 to 6, characterized in that the components defined in claim 1 are brought into contact with each other. 8. Adhesive composition according to one of claims 1 to 6, characterized in that it exhibits at least one of the following material properties (g) to (m): (g) drying time in normal climate 20/65-1 according to DIN 50014 at an applied amount of 250 g/m<2> in the range from 20 to 40 minutes, (h) drying time in normal climate 20/65-1 according to DIN 50014 at an applied amount of 400 g/m<2> in the range from 20 to 40 minutes, (i) viscosity at 25°C in the range from 300 to 150,000 mPa-s, (k) storage stability from 1 to 4 months, (I) NCO content in the range from 3 to 20% by weight, calculated on the adhesive composition, (m ) minimum pressing time according to DIN 68141 in the range from 5 to 8 hours. 9. Composite, characterized in that it contains at least a substrate and an adhesive composition according to one of claims 1 to 6 or 9. 10. Composite according to claim 9, characterized in that it has at least one of the following material properties: (n) a delamination resistance according to DIN EN 301, part 2, of a maximum of 5% according to DIN EN 301, (o) a dry shear strength in the range of at least 6 N/mm< 2> up to maximum substrate breakage according to the quality guidelines of the RAL-Gutergemeinschaft Holzleimbau. 11. Composite according to claim 9 or 10, characterized in that the substrate contains wood and is layer and/or wedge-comb glued. 12. Use of an adhesive composition according to one of claims 1 to 6 or 8, or a composite according to one of claims 9 to 11 in building, underground, ship, vehicle or aircraft construction. 13. Building, underground, ship, vehicle or aircraft construction, characterized in that it exhibits an adhesive composition according to one of claims 1 to 6 or 8, or a composite according to one of claims 9 to 11.