MXPA00005337A - Modified polyurethane hotmelt adhesive - Google Patents

Abstract

Hotmelt polyurethane adhesive compositions which are solid at room temperature and capable of being cured by moisture are obtained by combining the reaction product of a polyisocyanate and a low molecular weight polymer derived from ethylenically unsaturated monomers and containing active hydrogen groups such as hydroxyl with an isocyanate-containing polyurethane prepolymer derived from one or more polyols. The low molecular weight polymer component may, for example, be obtained by free radical polymerization of mixtures of unsaturated monocarboxylic acids, alkyl esters of unsaturated monocarboxylic acids, and/or hydroxyalkyl esters of unsaturated monocarboxylic acids.

Description

MODIFIED POLYURETHANE ADHESIVE FOR HOT FUSION Field of the invention This application relates to a polyurethane hot-melt adhesive that cures with moisture and quick curing, its production and use.

BACKGROUND OF THE INVENTION Hot-melt polyurethane adhesives that cross-link with moisture or cure with moisture are adhesives that are solid at room temperature and are applied in the form of a melt, their polymeric constituents containing urethane groups and reactive isocyanate groups. The cooling of the melt initially gives rise to a rapid physical hardening of the adhesive followed by a chemical reaction of the isocyanate groups still present, with moisture, to form an infusible, crosslinked adhesive. It is only after this chemical curing with moisture, accompanied by an increase in the size of the molecules and / or cross-linking, that the adhesive acquires its final properties. Polyurethane hot melt adhesives in the strictest sense are virtually solvent free.

The main advantages of hot melt adhesives over other adhesive systems lies in their very fast hardening capacity and in the absence of water and solvents in their composition. Polyurethane adhesives for hot melt, moisture curing, corresponding to join various substrates are known. Thus, DE-A-32 26 313 discloses a hot melt adhesive containing a prepolymeric isocyanate, a thermoplastic polymer and a synthetic resin of low molecular weight. The prepolymeric isocyanate is a reactive polyurethane prepolymer of an aromatic diisocyanurate and / or a prepolymer of this diisocyanate with a short chain diol and a polyether and a polyester containing OH groups and a short chain diol. This hot melt adhesive is suitable for joining thermoplastics and thermosets, foams, painted surfaces, rubber, textiles, nonwovens, wood, metal and paper. For formulations proposed to have high initial strength and to be applied to porous materials, 5 to 40% by weight of thermoplastic polyurethane has to be used. Unfortunately, this increases the viscosity of the melt with the result that these adhesives can only be applied by spraying at very high temperatures.

A hot-curing hot-melt adhesive consisting of a polyurethane prepolymer A with hard and soft chain segments and terminal isocyanate groups and a urethane prepolymer B with soft chain segments and terminal isocyanate groups is also known. The prepolymer A is prepared in steps from a thermoplastic saturated polyester polyol with a molecular weight of 1000 to 6000 and a melting point of 50 ° C or higher, a polyol with a molecular weight of not more than 8000 and a diisocyanate. The prepolymer B is prepared from a polyol with a molecular weight not greater than 8000 and a diisocyanate. This polyol can be liquid at room temperature or it can have a melting point below 50 ° C. The 4,4'-diphenylmethane diisocyanate or toluene diisocyanate is said to be particularly preferred as the diisocyanate. Unfortunately, these hot melt adhesives require an elaborate production process. Both the prepolymer A and the prepolymer B are prepared in a three-step process or the polymers have to be prepared in two-step or one-step processes and subsequently mixed. The melt viscosity of these adhesives at 120 ° C is very high (> 1 million mPas) so that it is not only expensive to produce these adhesives, they are also unsuitable for spray application and other applications requiring low viscosity in the state melted EP-A-340 906 discloses a polyurethane hot-melt adhesives of quick hardening consisting of a mixture of at least two amorphous polyurethane prepolymers, both prepolymer having different glass transition temperatures. The first polyurethane prepolymer preferably has a glass transition temperature above room temperature, while the second polyurethane prepolymer has a glass transition temperature below room temperature. The polyurethane prepolymer with the greater vitreous transition preferably consists of a polyester diol and a polyisocyanate, while the polyurethane prepolymer with the glass transition temperature smaller preferably consists of a linear or slightly branched polyester or a polyether. Aromatic diisocyanates, such as 4,4'-diphenylmethane diisocyanates or 2,4-toluene diisocyanate, are said to be the preferred diisocyanates.-The viscosities of these hot-melt adhesives at 130 ° C are the range from when 30,000 to 90,000 mPas. According to EP-B-354 527, the hot-melt adhesives can be produced from the reaction products of polyisocyanates and hydroxypolyesters, the hydroxy-polyesters containing more than 50% by weight of an oxy-polyester hydroxide A. The hydroxyester polyester A synthesized from aliphatic diols, optionally ether diols and aliphatic dicarboxylic acids containing from 8 to 12 methylene groups. The aliphatic dicarboxylic acids may optionally be partially substituted by aromatic dicarboxylic acids, although in a preferred embodiment - at least 50 mol% of the dicarboxylic acids consists of dodecandioic acid. The very fast curing speed of these hot melt adhesives is attributed to their rapid recrystallization in the adhesive layer ~ after the application of the melt. The preferred fields of application are said to be the footwear industry, the wood processing industry, the paper industry and the metal processing industry. EP-A-369 607 discloses polyurethane adhesives for hot-melt curing in moisture, rapid hardening based on polyurethanes containing at least one polyether-based prepolymer with a vitreous transition temperature above room temperature and a second polyurethane prepolymer with a vitreous transition temperature below room temperature. The second polyurethane prepolymer may be based on an amorphous polyester, a linear or slightly branched polyether or a polybutadiene. Polyols with a molecular weight of, preferably 250 to 800 and, more preferably, about 400 are proposed for the polyurethane prepolymer at the high glass transition temperature. This gives rise to relatively high isocyanate contents in the final hot melt adhesive so that it can only be applied in thin layers to avoid foaming under the effect of the carbon dioxide formed from the reaction of moisture with the isocyanate. According to EP-A-248 658, hot-melt polyurethane hot melt adhesives can be produced from a reaction product of crystalline diisocyanates and polyester diols, the crystalline polyester diols having been prepared from aromatic dicarboxylic acids , symmetrical and having an acid component of at least 50 mol%. In the preferred embodiments, the free isocyanate groups are blocked, for example, by acetone. Although this measure reduces the sensitivity of the hot melt adhesive to moisture and thus increases the stability during storage, the rate of hardening increases significantly because the isocyanate group must first be converted back into its reactive form in a step of Unlocking in view of the application temperature. EP-A-472 278 discloses an adhesive composition consisting of a polyalkylene ether diol, a polyalkylene-triol ether, a polyester polyol and an aliphatic isocyanate compound. The isocyanate compound is preferably a non-aromatic organic polyisocyanate, cyclic or linear aliphatic with a functionality of 2 to 4 and preferably of 2 to 3. The polyalkylene ether diols are, in particular, polytetramethylene ether diol, polyethylene glycol, polypropylene glycol or polybutylene ether diol, with polytetramethylene glycols being preferred. Polypropylene ether triols are preferred for polyalkylene ether triols. The preferred polyester polyol is a lactone-based polyether polyol such as polycaprolactone for example, a polycaprolactone triol from the reaction of caprolactone with trimethylolpropane being particularly preferred. The effectiveness of this hot melt adhesive is attributed to the relatively high crystallinity of the urethane segment based on polyester polyol. The adhesive composition is suitable for use on fabrics, nonwovens, wood, metal, leather and plastics. The viscosities in the melted state of the adhesives are not mentioned. Also, a modified polyurethane adhesive composition consisting of an isocyanate-terminated prepolymer with a molecular weight of at least 1000 and 2.5 to 100% by weight, based on the aforementioned prepolymer, of a reaction product of 2-dicarbamate ester of an organic diisocyanate and 1 mole of a low molecular weight dihydroxy compound such as, for example, ethylene glycol, diethylene glycol / propylene glycol, butan-1,4-diol, and the like. The ester dicarbamate must subsequently be added to the polyurethane pre-polymer because it can not be added during the polymerization of the prepolymer. This includes UXL additional work step that makes the product even more expensive for its production. Lamination of films and packaging materials, lamination of insulating materials and production of cushioning for the automotive industry are the common applications mentioned. EP-A-511 566 discloses a polyurethane hot melt adhesive of a polyfunctional polyether and / or polyester polyol which is liquid or highly viscous at ambient temperature, a polyfunctional polyol component, with a molecular weight of 500 to 10,000, which it is crystalline at room temperature and a mixture of polyisocyanates. The polyisocyanate component mixture contains an isocyanate with two differently reactive isocyanate groups and a diisocyanate with an isocyanate reactivity to hydroxyl groups that is greater than that of the less reactive isocyanate group of the polyisocyanate component containing two differently reactive isocyanate groups. The polyisocyanate component containing the isocyanate groups with different reactivity is preferably 2,4-toluene diisocyanate or the asymmetrically substituted derivatives of diphenylmethane diisocyanate or isophorone diisocyanate. In a preferred embodiment, the second diisocyanate compound is 4,4"-diphenylmethane diisocyanate or hexamethylene diisocyanate.The functional OH polyester polyols, preferably the products of adipic acid condensation corr butan-1, -diol or hexan -1,6-diol are mentioned as the crystalline polyol component at room temperature Mixtures of functional polyether polyols with OH, for example, propylene glycols and / or polyethylene glycols, are mentioned as the polyol component which is liquid or highly viscous. at room temperature High viscosity hot melt adhesives are particularly suitable for joining window glass and headlight diffusers, ie glass / plastic compounds for the automotive industry. Preferred are other low viscosity hot melt reactive urethane adhesive compositions which consist of: low molecular weight polymers formed from ethylenically unsaturated monomers containing no active hydrogen. - ~~ - urethane prepolymer having an isocyanate content of 0-25 to 15% and an isocyanate index greater than 1 and not greater than about 2.

This hot melt having a viscosity of 3000 to 50,000 mPas at 120 ° C can be easily coated on the substrates to be joined. According to this rence there is no need to incorporate plasticizers and / or thickeners in the adhesive formulation. In a preed embodiment, the low molecular weight polymers are formed by polymerization of ethylenically unsaturated monomers having active hydrogen in the isocyanate-free components of the isocyanate-terminated prepolymer prior to their reaction with the polyisocyanate. adhesives for hot melt where the low molecular weight polymer of the ethylenically unsaturated monomers contains at least one functional group reactive to moisture but not having active hydrogen This functional group can be an alkoxysilane group or an isocyanate group. hot melt polyurethane wet cure more known have serious disadvantages that, until now, have been an obstacle to economic use in difnt applications of adhesives.The properties that need to be improved are, among others: - the adhesive must be able be applied at low melt temperatures that heat-sensitive substrates can be joined (eg, polyolefin foams). - the adhesive must have a low viscosity at application temperatures to ensure that coatings can be applied by spraying or with rollers.

- The open time must be easily adjustable to comply with the requirements of the consumer. - It should be possible to use polyether polyols or normal polyester polyols, which are not expensive. - the production process should be simple, that is, the number of required components should be as small as possible. - the product must adhere to many difnt substrates. - the bonded adhesive must be sufficiently strong and still flexible in use, and must also ensure adequate resistance to plastic deformation. The viscosity of the melted adhesive must be sufficiently stable during production, packaging and application.

Although hot melt adhesives made in accordance with the prior art attempt to solve many of the aforementioned problems, they have major disadvantages: if the low molecular weight polymer incorporated in the adhesive formulation does not contain functional groups, they do not have chemical linkage in them. The main chain of the adhesive after the adhesive is cured. In this way it is easily extracted from the solvent-cured adhesive by foaming in contact with the bonding line. In addition, plasticizers that migrate from the interface of the tie line of the plasticized substrates also extract significant portions of the low molecular weight polymer from the cured adhesive. This loss of the low molecular weight component due to contact with the solvent and / or plasticizer is highly undesirable, since it changes the physical, chemical and especially mechanical properties of the bond line and thus the functioning of the bonded parts. - if the low molecular weight polymer contains moisture-reactive functional groups such as alkoxysilanes or isocyanates, these have to be prepared, stored and handled under anhydrous conditions before they are incorporated into the hot melt adhesive composition. - further, with exposure to moisture, an alkoxysilane group separates a monofunctional alcohol which acts as a chain retainer for the isocyanate groups of the hot melt composition. Such interruption of the chain effectively damages the re-entitling process, thus reducing the final strength of the cured adhesive.

The problem solved by the present invention was to preserve the favorable properties of the reactive polyurethane adhesives for hot melt containing low molecular weight polymers and to improve their resistance to solvents and / or plasticizers. It should be noted that all quantities used in-ahead, except in the examples, should be understood as modified by "approximate".

COMPENDI OF THE INVENTION The solution according to the invention is defined in the clauses and consists of a composition for hot melt polyurethane that is cured with moisture, practically without sot that is solid at room temperature containing 95 to 3% by weight of the product of reaction of a polyisocyanate and a low molecular weight polymer comprising ethylenically unsaturated monomers, wherein the polymer has a hydrogen group. active, from 5 to 90% by weight of at least one polyurethane prepolymer with free isocyanate groups prepared from at least one polyol selected from the group consisting of polyether diols, polyether triols, polyester polyols and mixtures thereof and when minus one polyisocyanate, and 0 to 40% by weight of additives selected from the group consisting of thickeners, plasticizers, fillers, pigments, stabilizers, adhesion promoters and mixtures thereof, their use and articles of manufacture prepared with the miso Detailed description of the invention A "polyurethane prepolymer" is understood as an oligourethane containing reactive isocyanate groups which are formed by the reaction of hydroxy-functional compounds with a more than stoichiometric amount of polyisocyanates, thus giving rise to compounds with free isocyanate groups (reactants). The polyisocyanates in this context are preferably low molecular weight compounds containing two isocyanate groups, although these may contain up to 10% by weight of trifunctional isocyanate and / or of higher functionality. However, undesired crosslinking can be observed in the production and use of the hot melt adhesive if the amount of polyisocyanates with functionality of 3 or more is too high. Although aromatic polyisocyanates are the most preferred isocyanates, it is also possible to use aliphatic and / or cycloaliphatic polyisocyanates. Examples of the suitable aromatic polyisocyanates include: any of the isomers of polyisocyanate de-toluene (TDI) in the form of pure isomers or in the form of a mixture of some isomers, 1,5-naphthalene diisocyanate (NDI), , naphthalene diisocyanate (NDI), 4,4'-diphenylmethane diisocyanate (MDI), 2,4 '-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), 4'-diisocyanate 2, 2- diphenylpropane, p-phenylene diisocyanate, m-phenylene diisocyanate, 4,4 '- diphenyl diisocyanate, 4,4' - diphenylsulfone diisocyanate, 1,4-chlorobenzene 2,4-diisocyanate, 4,4 ', 4" di-triphenylmethane-diisocyanate, 1, 3, 5-benzene diisocyanate, toluene-2,4,6-triisocyanate and furfurilidene diisocyanate. Examples of suitable cycloaliphatic polyisocyanates include 4, '-dicyclohexylmethane (Hi2MDI), 3,5,5-trimethyl-3-isocyanatomethyl-1-isocyanato-cyclohexane diisocyanate (isophorone diisocyanate, IPDI), 1,4-diisocyanate Cyclohexane, cyclohexane 1,2-diisocyanate, hydrogenated xylylene diisocyanate (H6XDI), m- or p-tetramethylxylylene diisocyanate (m-TMXDI, p-TMXDI) and dimeric acid diisocyanate. Examples of the aliphatic isocyanates include 1,6-diisocyanate-hexane (HDI), 1,6-diisocyanate, 2,2,4-trimethylhexane, 1,6-di-4,4-trimethylhexane diisocyanate, 1, butane diisocyanate and 1,2-dodecane diisocyanate (Ci2DI). Particularly preferred for maximum formulation stability is a liquid mixture of 4,4'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate. Under certain conditions it may be advantageous to use mixtures of the aforementioned polyisocyanates. The hydroxy functional compounds (ie, "polyols") for preparing the polyurethane prepolymer can be selected from polyether polyols, polyester polyols and / or aromatic polyols. It is understood that a "polyether polyol" is a linear polyether having mainly two OH groups. Preferred polyether polyols are diols corresponding to the general formula H0 (-R-0) m-H, where R is a hydrocarbon radical containing from 2 to 4 carbon atoms and m is in the range from 4 to 225 on average. Specific examples of these polyether polyols include polyethylene glycol, polybutylene glycol, polytetramethylene glycol (poly THF) and, above all, polypropylene glycol (R = -CH2CH (CH3) -). These polyether polyols can be prepared by known methods such as, for example, polymerization of one or more cyclic ether monomers such as ethylene oxide, propylene oxide, n-butene oxide and tetrahydrofuran. The polyether polyols can be used as homopolymers and as copolymers, as block copolymers and as statistical (random) copolymers. Preferably only one type of polyether polyol is used, although mixtures of 2 to 3 polyether polyols different in their average molecular weight and / or in the nature of their structural elements can also be used. Small amounts of a trifunctional polyether polyol (ie, a polyether triol) may also be present in the mixture. The average molecular weight (number average molecular weight) of the polyether polyols is in the range from 200 to 10,000, and preferably in the range of 400 to 6000. It is understood that a "polyether polyol" is a polyester having more than one group OH, preferably two terminal OH groups. The preparation is by the known ways of: a) aliphatic hydroxycarboxylic acids, or b) aliphatic and / or aromatic dicarboxylic acids having from 6 to 12 carbon atoms and, particularly in even numbers, diols having from 4 to 8 carbon atoms.

Of course, it is possible to use other suitable derivatives, lactones, methyl esters or anhydrides. Specific starting materials include: 1, -butanediol, 1, 6-hexanediol, 1-10-decanediol, 1, 12-dodecanediol, adipic, azelaic and sebacic acids, 1, 10-decanedicarboxylic acid, and lactones. The acid component can include up to 25% on a molar basis of other acids, for example, cyclohexanedicarboxylic acid, terephthalic acid and isophthalic acid. The glycol component can include up to 15% on a molar basis of other diols, for example, diethylene glycol and 1,4-cyclohexane dimethanol. In addition to the homopolymers of the above components, especially, copolyesters of the following components or derivatives thereof are of importance: 1. adipic acid, isophthalic acid, phthalic acid and butanediol; 2. adipic acid, isophthalic acid, and hexanediol; 3. adipic acid, isophthalic acid, phthalic acid, ethylene glycol, neopentyl glycol and 3-hzL-hydroxy-2, 2-dimethylpropyl-3-hydroxy-2,2-dimethyl propanoate; and 4. adipic acid, phthalic acid, neopentyl glycol and ethylene glycol.

The copolyester of adipic acid, isophthalic acid, phthalic acid and butanediol is partially crystalline and has high viscosity. Therefore, this gives rise to a high initial strength, the copolyester of adipic acid, phthalic acid and hexanediol have low vitreous transition temperature and thus gives rise to better flexibility at low temperature. Suitable polyester polyols can optionally be slightly branched, that is, small amounts of a tricarboxylic acid or trihydric alcohol have been used in their production. Thus, polyester polyols are liquid or solid. In case they are solid, they are preferably amorphous, however, they can be weakly crystalline as well. Preferably, a mixture of partially crystalline and amorphous polyester is used. However, the crystallinity develops so weakly that it is not seen as turbidity in the final hot melt adhesive. The melting point of the partially crystalline polyester is in the range from 40 to 70 ° C, preferably in the range from 45 to 65 ° C. The melting point indicates the temperature at which the crystalline regions of the material will melt. This is determined by differential thermoanalysis through the main endothermic peak. Preferably, an adipate gives polybutanediol having a molecular weight of 3500 and a melting point of 50 ° C is used as the partially crystalline polyester glycol.

The average molecular weight (Mn) of the polyester polyol should be between 1,500 and 30,000, preferably between 2,500 and 6,000. This is calculated from the OH number. The molecular weight of the polyester polyol is of some importance: an increase in molecular weight hinders the extrusion of the hot melt adhesive and the penetration into the porous substrates, and a decrease in molecular weight causes the hot melt adhesive err to not be sufficiently solid at room temperature. The polyester polyols have a glass transition temperature (Tg) in the range of preference from -40 ° C to + 50 ° C and, in particular, in the range of -40 ° C to + 40 ° C. The Tg is determined based on the CED measurements "as the central point of the passage using a ratio of 10 ° C / minut in the second process Particularly suitable polyester polyols include those having temperature __ of vitreous transition from about -40 ° C to + 40 ° C, a viscosity of 3,000 to 30,000 mPa.s at 130 ° C (Brookfield, RVDV II + Thermosel) and a hydroxyl number of 2 to 80, preferably 2 to 40 mg of KOH / g) By "aromatic polyol" is meant a product of the alkoxylation of an aromatic polyhydroxyl compound., in particular, the reaction products of ethylene oxide and / or propylene oxide with aromatic dihydroxy compounds such as, for example, hydroquinone, resorcinol, pyrocatechol, bis- (hydroxydiphenyl), bisphenol A, bisphenol F, isomers of dihydroxynaphthalene (pure isomers or a mixture of some isomers), isomers of hydroxyanthracene (pure isomer or mixture of isomers) or isomers of dihydroxyanthraquinone. From 1 to 7 alkoxy units have preferably been added by aromatic hydroxy group. By "low molecular weight polymer of ethylenically unsaturated monomers having active hydrogen" is meant a polymer prepared from one or more of the following comonomers including: Ci alkylesters of acrylic acid, Ci alkydsters of methacrylic acid , acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate (HEMA), hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, esters of (meth) acrylic acid and oligomers and polymers of glycol as di- , tri-, tetra- and / or polyethylene glycol esters of (meth) acrylic acid and glycol ethers such as methoxyethanol and / or ethoxyethanol, vinyl esters such as vinylacetate, vinylpropionate, vinyl esters of highly branched monocarboxylic acids (such as vinylester of versatic acid sold by Shell Chemicals), vinyl ethers, fumarates maleates, styrene, alkyl styrenes, bu tadiene as well as acrylonitrile. Instead of or in addition to the hydroxy-functional (meth) acrylates, it is possible to use the corresponding aminofunctional monomers. The choice of the particular monomer or monomer mixture depends largely on the desired end use of the adhesives including suitability for the application equipment to be used, "low molecular weight polymers" in the sense of the present invention means a average molecular weight below 60,000. A range of molecular weight-. Preferred average is between 10,000 and 40,000, the most preferred range between 20,000 and 36,000. The average molecular weight is determined by normal gemeton permeation chromatography (GPC) sometimes also known as size exclusion chromatography (SEC).

The weight-average molecular weight (MW) is calibrated against an external standard of polystyrene of certified molecular weight. As already mentioned at the beginning, the low molecular weight polymers of the present invention have preferably active hydrogen groups in the form of OH groups, however amino groups and / or carboxylic groups may also be present. The amount of active hydrogen groups is determined by their OH number, as specified in DIN 53783. The OH number of these low molecular weight polymers should be in the range between 0.5 and 20, preferably between 1 and 15, the most preferred range being 2 to 10 mg KOH / g. In terms of weighted average hydroxyl functionality it is preferred that this value be between about 0.9 and about 8. Particularly preferred is a low molecular weight polymer having a weighted average hydroxyl functionality between about 1.2 and about 5. average hydroxyl functionality weighted is equal to the weight average molecular weight of the polymer for the polymer fraction by the weight fraction of the hydroxy functional monomer (such as for example hydroxyethyl methacrylate) divided by the molecular weight of the hydroxy-functional monomer. Low molecular weight (MW) polymers having active hydrogen groups are thermoplastic polymers and can be produced by known processes, that is, they can be prepared by ionic, thermal polymerization and preferably by free radicals. The active hydrogen groups can be incorporated into the polymer - using a free radical initiator having active hydrogen groups and / or using a chain transfer agent carrying active hydrogen groups. The addition of small amounts of comonomers carrying active hydrogen groups, such as monomers of Hydroxyfunctional (meth) acrylate mentioned above to the monomer mixture is a third possible alternative.

While the first two methods generate mainly terminal functional groups, the third method generates functional groups statistically distributed along the polymer chains. Other details of the three methods can be found for example in EP-A-205846 and the references mentioned therein. Since these polymers are produced by free radical polymerization, the functional groups will be randomly distributed in the polymer and individual chains. This implies that, especially with very low OH numbers, a certain number of polymer molecules may not carry any functional group while others may carry two or more functional groups. The low molecular weight polymers with an active hydrogen group can be prepared according to any of the known aqueous or anhydrous polymerization processes. These can also be polymerized in one or more of the polyether polyol (s) and / or polyester polyol (s). The hot melt adhesive, according to the present invention, may also contain one or more of the following: catalysts, stabilizers, thickener resins, fillers, pigments, plasticizers, adhesion promoters and / or rheology improvers . The optional catalysts can accelerate the formation of the polyurethane prepolymer during its production and / or the curing / crosslinking process with moisture after the application of the hot-melt adhesive. Suitable catalysts are the normal polyurethane catalysts, such as divalent and trivalent tin compounds, more specifically divalent tin dicarboxylates and dialkyl tin dicarboxylates and dialkoxylates. Examples of these catalysts are dibutyltin dilaurate, dibutyltin diacetate, dioctyltin diacetate, dibutyltin maleate, tin octoate (II), tin phenolate (II) or even divalent and tetravalent tin acetylacetonates. Highly effective tertiary amines or amidines can also be used as catalysts, optionally in combination with the aforementioned tin compounds. Suitable amines are acyclic and, in particular, cyclic compounds. Examples include tetramethylbutanediamine, bis- (dimethylaminoethyl) -ether, 1,4-diazabicyclooctane - (DABCO), 1,8-diazabicyclo- (5.4.0) -undecane, 2,2 '-dimorpholinodiethylether or dimethylpiperazine or "still mixtures of the amines mentioned above - However, unexpectedly it has been found that for applications requiring optimum machinability it is desirable to minimize or eliminate the tin catalysts. "Stabilizers" in the context of the present invention include stabilizers that they stabilize the viscosity of the polyurethane polymer during its production, storage and application, suitable stabilizers of this type include, for example, monofunctional carboxylic acid chlorides, highly reactive monofunctional isocyanates and non-corrosive inorganic acids. benzoyl, toluenesulfonyl isocyanate, phosphoric acid or phosphorous acid. is in the context of the present invention include antioxidants, UV stabilizers or hydrolysis stabilizers. The choice of these stabilizers is determined by a part of the main components of the hot-melt adhesive and on the other hand by the conditions of application and by the loads to which the joint will probably be exposed. When the polyurethane prepolymer is mainly composed of units -p >olieter, antioxidants are mainly necessary, optionally combination with UV stabilizers. "Examples of suitable antioxidants include commercially available hindered phenols and / or thioethers- and / or substituted benzotriazoles.In cases where the main components of the polyurethane prepolymer consist of polyester units, they are preferably used Hydrolysis stabilizers, for example carbodiimide type Examples of suitable thickener resins include abietic acid, abietic acid esters, terpene resins, terpene / phenol resins or hydrocarbon resins Examples of fillers include silicates , talc, calcium carbonate clays or carbon black Suitable rheology improvers that impart thixotropy or resistance to runoff are, for example, Bentone (a rheological additive available from Rheox), hydrogenic (smoked) silicas, urea derivatives and fibrilates or pulped staple fibers, although adhesion promoters are often not required In addition, the aforementioned thickener resins such as abietic acid, terpene resins, terpene / phenol resins or hydrocarbon resins also act as adhesive promoters. In special cases, organofunctional silanes such as 3-glycidyl-oxypropyl trialkoxy silane-epoxy functional or isocyanate ethyl isocyanate isocyanate functional isocyanate, epoxy resins, melamine resins or phenolic resins can be added as adhesion promoters. The hot melt polyurethane adhesive composition according to this invention can be prepared, for example, in three different ways: In a two-step process, the low molecular weight polymer containing the functional group of the ethylenically unsaturated monomers and the polyol or polyol mixture are each reacted separately with the polyisocyanate component. In a subsequent step, the prepolymer (s) capped with the isocyanate group thus formed including the low molecular weight polymer topped with the NCO group are mixed, optionally followed by mixing the catalysts, stabilizers, material thickener resins of charge, pigments and the like. It may be necessary to dissolve the molecular weight polymer in an inert, low-boiling solvent prior to the reaction with the polyisocyanate. If so, the solvent will be evaporated at a later stage of production. In another embodiment, the low molecular weight polymer containing a functional group from the ethylenically unsaturated monomers is reacted with a stoichiometric excess of isocyanate in an internal, continuous mixer, or in an extruder with sufficient residence time to allow the reaction complete of the functional groups with the polyisocyanate. It is also possible to carry out the subsequent mixing in the internal mixer or extruder. It can also be done in any suitable mixer capable of homogenizing high viscosity components under the exclusion of moisture. In a one-step process, the low molecular weight polymer containing the functional group from the ethylenically unsaturated monomers and the polyol or the mixture of polyols are homogenized, followed by the reaction of this mixture with the polyisocyanate. You can follow the mixing of the aforementioned auxiliary components. The preferred mixing equipment for the one-step process is also an internal mixer / extruder-type mixing equipment since the components with high viscosity need to be homogenized rapidly, especially during and immediately after the addition of the polyisocyanate. In one embodiment, the low molecular weight polymer containing the functional group from the ethylenically unsaturated monomers is mixed with a small polyol portion or polyol mixture. The viscosity of this mixture should not exceed 80,000 mPas at 130 ° C prior to the addition of the polyisocyanate, thus allowing the use of traditional tank mixing equipment with stirring. This mixture is then reacted with the entire polyisocyanate followed by the addition of the remaining portion of the polyol or the mixture of polyols. This procedure avoids the use of solvents during production without risking partial gelling even when low molecular weight polymers are used coming from the ethylenically unsaturated monomers having high OH or NH functionality, furthermore, during the whole reaction, the viscosity of the composition follows being too low to avoid a high power extruder as mixing equipment.

The viscosity of the resulting hot melt polyurethane compositions according to the present invention is preferably in the range from 2000 to 50, TJ00 mPas at 130 ° C. As already mentioned, these compositions are solid at room temperature. Due to their rapid solidification with cooling, these adhesives exhibit a high adhesive and cohesive initial strength even before completing the curing / crosslinking reaction of the isocyanate groups with moisture coming from the air and / or the adhering substrate. This guarantees a high resistance to the fast handling of the adhered substrates that can be quickly subjected to other processing operations without the need for fixation and / or mechanical fastening. Due to these properties, the hot melt adhesives according to this invention can be easily adapted to a series of applications where hot melt materials are commonly used, especially for demanding applications that require: a high degree of thermal resistance, resistance to moisture. resistance to attack by solvents and / or plasticizers.

Common applications include, but are not limited to, the laminated woodworking industry including the joining of wood panels, the assembly of automotive interiors, the bonding of roofing panels, the manufacture of non-woven fabrics, manufacturing- abrasive discs, abrasive paper and the like. It is considered that the superior properties of the hot melt adhesive according to the present invention are due to the at least partial chemical bonding of the low molecular weight polymer from the ethylenically unsaturated monomers to the polyurethane polymer. - EXAMPLES The invention will also be illustrated by the following examples. However, it will be understood that these examples are not intended to limit the scope of the invention, they are included to illustrate the preferred embodiments of the invention.

A common formula would be: -40 parts by weight (pep) of PPG 10-20 pep of Elvacite 2820 13-19 pep of MDI - 15-30 pep polyester diol 2 pep Modaflow 2100 ~~~~ where: PPG is polypropylene glycol MDI is 4,4'- or mixture of 2,4 '/ 4,4' Elvacite 2820 is Elvacite 2013 containing OH. This has a CAS # of 35227-05-5. The name CAS: poly-methyl methacrylate / methacrylic acid / 2-hydroxyethyl methacrylate / n-butyl methacrylate). The average molecular weight weighted around 25K. The average functionality around 1.5-2. Elvacite is a registered trademark of ICI Acrylics, Wilmington, DE. Modaflow 2100 is an additive for non-reactive surface coatings available from Montasanto.

EXAMPLE 1 It was prepared as described above.

PPG-1025: 38 pep - Elvacite 2901: 23 pep Mondur ML: 17.5 pep Modaflow 2100: 1.5 pep Ruco S-105-30: 20 pep Note: PPG 1025 is polypropylene glycol, MW = 1000 Elvacite 2901: methyl methacrylate / butyl methacrylate copolymer with 1.5% by weight of HEMA Mondur ML: 2, 4 '/ 4, 4' -MDI mixture available from Bayer Modaflow 2100 : agent for Ruco fluidity S-105-30: poly (hexane adipate) diol available from Ruco PM ~ 3500 EXAMPLE 2 It was prepared as already described PPG-1025: 18 pep PPG-2025: 22 pep Elvacite 2901 25 pep Mondur ML: 15.7 pep Modaflow 2100 1.5 pep Ruco S-105-30: 11.5 pep Ruco XS-7129: 6.3 pep Note: PPG-2025 is polypropylene glycol having a molecular weight of approximately 2000. Ruco XS-7129 is a polyester diol available from Ruco.

EXAMPLES 3 TO 9 AND COMPARATIVE EXAMPLE The hot melt adhesive compositions, reactive, were prepared in the following manner: • 44.2 pep polypropylene glycol diol, MW 2000", OH 56 ratio • 171.7 pep poly (hexane adipate) diol, MW ~ 3500 • 24.5 pb copolymer containing methacrylate containing OH groups similar to Elvacite 2013. • Approximately 10.2 pbm MDI (mixture of 2, 4 '-4, 4') • 0.03 pb of toluenesulfonyl isocyanate as stabilizer In the individual formulations, the amount of MDI was adjusted to accommodate an NCO: OH ratio of 1.65.

Table 1 Exerppl Copolime Indicate Time Thickness Viscid Viscid Resist Resist Resist Resist Matter or ro ad oo of ad ad (16 cia a la cia a la cia a la cia a la extrac acrylic OH open dry (130 ° C) h / 130 ° C) shear shear shear shear table PM to o [MPA]. { MPa.s] at RT at 80 ° C at 100 ° C to 130 ° C [% in [sec] [sec] [Mpa] [Mpa] [Mpa] [Mpa] weight] 3 2100b 2.0 360 120 1825 3800 7.4 1.9 1.9 2.2 13.9 4 34000 2.0 210 80 630Q 8200 9.3 1.3 1.1 1.1 13.6 12000 8.6 390 130 3550 11950 6.3 1.8 1.0 1.2 15.9 6 21Ú00 8.6 380 65 6180 16700 7.4 1.9 1.8 1.2 11.6 7 34000 2.0 100 30 14150 20300 8.3 1.7 1.7 1.1 16.2 8 21000 3.9 190 100 3750 8350 9 21000 3.9 200 110 2115 4725 compar 34000 0.0 240 40 9300 14250 9.0 1.8 1.6 1.1 16.2 ativo Table 2 e = excellent b = good f = regular m = bad fs the substrate failed Note The composition of Example 7 contained 44.2 pb of a mixture of 79% ep of polyoxypropylene diol "" 21% ep of polyoxypropylene triol based on the total polyether polyol in addition to the poly (hexane adipate) diol. As can be seen from table 1, the hot melt adhesive compositions of Examples 2 to 7 are as good as the "state of the art", the comparative example containing the non-functional methacrylate copolymer Elvacite 2013) with respect to open time, the hardening time of the range of viscosity and stability of viscosity. The stability of the viscosity is determined by maintaining the adhesive composition (excluding moisture) for 16 hours at 130 ° C.

Also the shear strength after the final curing, ie, after 7 days of exposure to moisture at room temperature and elevated temperatures are at least equivalent to the state of the art. To determine the extractable matter of the cured adhesive compositions , the cured samples were subjected to extraction in soxhiet with methylene chloride - for 6 hours. Afterwards, the extracted samples were dried in an oven with ventilation at 75 ° C, to determine the matter extracted by weight loss. The cured samples prepared from the compositions according to the invention exceed the composition of the state of the art by a factor of two in terms of reduction of extractable matter. The adhesives were tested for adhesion properties on the following substrates (see Table 2) Soft PVC, ie plasticized PVC, rigid PVC, polyethylene (PE, surface treated with fluorine), paper, clear chlorine ABS ( acrylonitrile-butadiene-styrene) ABS with black color, PS (polystyrene). Although there is little or no difference in the performance of adhesion in PS, ABS, paper or PVC, soft, the compositions of the present invention show. much better adhesion to fluorinated polyethylene _ and rigid PVC: the adhesion of the adhesives according to the invention on fluorinated PE or rigid PVC being at least regular or good, while the comparative example worked bad or regular, respectively. Without wishing to adhere to any theory, it is considered that the foregoing formulations form block copolymers / acrylic grafts or ethane. To create these -block / grafted copolymers, acrylic polymers containing hydroxyls were used. These acrylic polymers react with isocyanate to be incorporated into the polyurethane prepolymers. These reagent hot melt adhesives have excellent performance; The copolymers showed excellent strength before curing, long processing time and good stability in the molten state, even with exposure to moisture.

Claims (6)

1. An adhesive composition for hot melt polyurethane cured with moisture, without solvents, wherein the hot melt adhesive composition is solid at room temperature, consists of the product of combining: a) about 95 to about 3% by weight of the reaction product of a first polyisocyanate and a low molecular weight polymer, containing ethylenically unsaturated monomers, wherein the polymer has active hydrogen groups; b) about 5 to about 90% by weight of at least one polyurethane prepolymer "with free isocyanate groups prepared from at least one polyol selected from a group consisting of polyether diols, polyether triols, polyester polyols, aromatic polyols and mixtures of them and at least one second polyisocyanate which may be the same or different from the first polyisocyanate, c) from 0 to about 40% by weight of at least one additive selected from the group consisting of catalysts, thickeners, plasticizers, fillers, pigments, stabilizers, adhesion promoters, rheology improvers and mixtures thereof, wherein the sum of a), b) and c) is 10 ~ 0% by weight The hot melt adhesive composition of claim 1 , wherein the polyether diol is selected from the group consisting of polyethylene oxide diols, polypropylene oxide disols, polyethylene oxide triols, triols and polypropylene oxide, diol copolymers of ethylene oxide and propylene oxide, triol copolymers of ethylene oxide and propylene oxide, diols of butylene oxide, triols of butylene oxide and mixtures thereof. The hot melt adhesive composition of claim 1, wherein the polyester polyol is an OH-terminated condensation product of C2-C? -β dicarboxylic acids and a diol selected from the group consisting of C2-C alkylene? diols, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol and mixtures thereof. The hot melt adhesive composition of claim 3, wherein the polyester polyol component further contains triols selected from the group consisting of glycerol, trimethylolpropane, triethylolpropane and mixtures thereof. The hot melt adhesive composition of claim 1, wherein the polyester polyol is prepared from e-caprolactone. The hot melt adhesive composition of claim 1, wherein the first and second polyisocyanates are selected from the group consisting of: naphthalene 1,5-naphthalene-1,4-naphthalene diisocyanate, 4,4-diisocyanate '-diphenylmethane, 2,4'-diisocyanate-diphenylmethane, xylylene diisocyanate, 4,4'-2,2-diphenylpropane diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, 4,4' '- diphenyl diisocyanate , 4"-difenylsulfone diisocyanate, of furfurilidene, 2,4-diisocyanate of 1-chlorobenzene, A, 4 ', 4" -diisocyanate-of triphenylmethane, -1, 3, 5-diisocyanatobenzene, 2, 4 , 3,4-triisocyanato-toluene di-4-cyanohexyl-2,4-diisocyanate, 3, 5, 5-trimethyl-3-isocyanatomethyl-1-isocyanato-cyclohexane, 1,4-cyclohexane diisocyanate, 1,2-cyclohexane diisocyanate, diisocyanate of hydrogenated xylylene, m- or p-tetramethylxylylene diisocyanate, diisocyanate "of dimeric acid, 1,6-hexane diisocyanate, 1,6-diisocyanate 2, 2,4-trimethylhexane, 1,6-diisocyanate, 2,4-trimethylhexane, 1,4-butane diisocyanate, 1,1-dodecane diisocyanate and mixtures thereof. The hot melt adhesive composition of claim 1, wherein the ethylenically unsaturated monomers are selected from the group consisting of: Ci alkylesters of acrylic acid, C 1 to 8 alkylesters of methacrylic acid, alkylesters of Ci a Cie of crotonic acid, z alkylesters of Ci to Cie of maleic acid, C1 to C2 alkylesters of fumaric acid, Ci to C ak alkyl esters of taconic acid, (meth) acrylic acid hydroxyethyl ester, (meth) acrylic acid hydroxypropyl ester, styrene, butadiene and mixtures thereof. The hot melt adhesive composition of claim 1, wherein the ethylenically unsaturated monomers are selected from the group consisting of: Ci alkylesters of acrylic acid, Ci to C 8 alkylesters of methacrylic acid, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, (meth) acrylic acid esters, and glycol oligomers and polymers, esters of (meth) acrylic acid and glycol ethers, vinyl ethers, vinyl esters, fumarates, maleates, styrene, - alkylstyrenes, butadiene, acrylonitrile and mixtures of. the same. 9. The hot melt adhesive composition of claim 1, wherein the low molecular weight polymer has a hydroxyl number below. about 15 mg KOH / g determined according to DIN 53783. The hot melt adhesive composition of claim 1, wherein the low molecular weight polymer has a hydroxyl number between about 0.5 and about 20 mg of KOH / g determined according to DIN 53783. 11. The hot melt adhesive composition of claim 1, wherein the low molecular weight polymer has a hydroxyl number between about 1 and about 15 mg KOH / g determined in accordance with DIN 53783. 1

2. The hot melt adhesive composition of claim 1, wherein the low molecular weight polymer has a weighted average hydroxyl functionality between about 0.9 and about 8. 1

3. The hot melt adhesive composition of claim 1, wherein the low molecular weight polymer has a weighted average hydroxyl functionality between about 1.2 and about 5. 1

4. The hot melt adhesive composition of claim 1, wherein the low molecular weight polymer has a weight average molecular weight between about 10,000 and 40,000 determined by gel-permeation chromatography. 15, The hot melt adhesive composition of claim 1, wherein the molecular weight of the low molecular weight polymer is between about 20,000 and approximately 36,000, determined by gel permeation chromatography. 16, The hot melt adhesive composition of claim 1, wherein the composition is substantially free of tin catalysts. The hot melt adhesive composition of claim 1, wherein the first and second polyisocyanates are liquid mixtures of diisocyanate 4, 4 '-diphenylmethane and 2,4'-diiphenylmethane diisocyanate. A process for bonding substrates with hot melt adhesive, wherein the improvement consists in bonding the substrates with the hot melt adhesive of claim 1. 19. The bonded substrates, produced by the process of claim 18. , A solvent-free, moisture-cured polyurethane hot melt adhesive composition, wherein the hot melt adhesive composition is solid at room temperature, consists of the product of combining: a) about 95 to about 3% by weight weight of the reaction product of a first aromatic polyisocyanate and a polymer having: i) an average molecular weight as determined by gel permeation chromatography of between about 10,000 and about 40,000, ii) a hydroxyl number between about 1 and about 15 mg KOH / g, and iii) a weighted average hydroxyl functionality between about 0.9 and about 8 and containing the ethylenically unsaturated monomers, wherein at least a portion of the ethylenically unsaturated monomers carry active hydrogen groups; b) from about 5 to about 90% by weight of at least one polyurethane prepolymer with free isocyanate groups prepared from at least one polyol selected from the group consisting of polyether diols, polyether triols, polyester polyols and mixtures thereof. same and at least one second aromatic polyisocyanate wherein the second aromatic polyisocyanate may be the same or different from the first aromatic polyisocyanate; c) from 0 to about 40% by weight of at least one additive selected from the group consisting of thickeners, plasticizers, fillers, pigments, stabilizers, adhesion promoters, rheology improvers and mixtures thereof, wherein the sum of a), b) and c) is 100% by weight. 21. The hot melt adhesive composition of claim 20, wherein the polymer is composed of at least one ethylenically unsaturated monomer having an active hydrogen group and selected from the group consisting of: group consisting of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate and mixtures thereof. 22. The hot melt adhesive composition of claim 20, wherein the first and second aromatic polyisocyanates are diphenylmethane diisocyanates. 23. The hot melt adhesive composition of claim 20, wherein the polyol is a mixture of: i) a polyether diol obtained from propylene oxide and, optionally, one or more other C2-C4 epoxides, ii ) a poly (ester) diol having a vitreous transition temperature from about -40 ° C to + 40 ° C, a viscosity of about 3000 to 30,000 mPa.s at 130 ° C, and a hydroxyl number from about 2 to about 40 mg KOH / g and, optionally, iii) a polyether triol obtained from propylene oxide and, optionally, one or more other C2-C4 epoxides. 24. The hot melt adhesive composition of claim 20, wherein the polymer has an average molecular weight in the range between about 20,000 and about 36,000, a hydroxyl number in the range of about 2 to about 10 mg. KOH / g, and an average-weighted hydroxyl functionality in the range between about 1.2 and about

5. 25. The hot melt adhesive composition of the. Claim 20, wherein the polymer has statistically active hydrogen groups distributed therein. 2

6. A solvent-free, moisture-cured polyurethane hot melt adhesive composition, wherein the hot melt adhesive composition is solid is solid at room temperature, consists of the product of combining: a) about 95 to about 3% by weight of the reaction product of a first diphenylmethane diisocyanate and a polymer having: i) an average molecular weight as determined by gel permeation chromatography of between about 20,000 and about 36,000, ii) a hydroxyl number between of 2 and about 10 mg KOH / g, and iii) a weighted average hydroxyl functionality between about 1.2 and about 5 and consisting of ethylenically unsaturated monomers, wherein at least a portion of the ethylenically unsaturated monomers is selected from the group consisting of in acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxy methacrylate ethyl, hydroxypropyl acrylate, hydroxypropyl methacrylate and mixtures thereof; b) about 5 to about 90% by weight of at least one polyurethane prepolymer with free isocyanate groups prepared from a polyol mixture composed of a polypropylene oxide diol, a poly (hexane adipate) diol and optionally , a polypropylene oxide triol and a second diphenylmethane diisocyanate, which may be the same as or different from the first diphenylmethane diisocyanate; and c) from 0 to about 40% by weight of at least one additive selected from the group consisting of thickeners, plasticizers, fillers, pigments, stabilizers, adhesion promoters, rheology enhancers and mixtures thereof; wherein the sum of a), b) and c) is 100% by weight.