Resole resins stabilized with urea derivatives

Abstract

The present invention relates to amine resole phenolic resins stabilized with a solubilizing agent selected from certain urea derivatives, sizing compositions made from said resins, a method for manufacturing fiber-based insulation products, in particular mineral wool-based insulation products, using said sizing compositions, and a method for manufacturing fiber-based insulation products, in particular mineral wool-based insulation products, in particular mineral wool-based insulation products, in particular mineral wool-based insulation products, in particular mineral wool-based insulation products, in particular mineral wool-based insulation products, in particular mineral wool-based insulation products. And a thermally and / or acoustically insulating product obtained by said manufacturing method.

Description

[0001] The present invention relates to an amine resol phenolic resin stabilized with a solubilizer selected from certain urea derivatives, an adhesive composition prepared from said resin, a process for producing fiber-based insulation products, in particular fiber-based insulation products based on mineral wool, using said adhesive composition, and thermal and / or acoustic insulation products obtained by said production process. Background of the Invention The production of mineral wool-based insulation products typically includes a step for producing the mineral wool itself, which can be performed by various methods, such as the known fiber production techniques of internal or external centrifugation. Internal centrifugation involves introducing molten mineral material (glass or rock) into a centrifugal device containing a large number of small holes. Under the influence of centrifugal force, the material is projected onto the peripheral wall of the device and exits in the form of filaments. External centrifugation, more suitable for rock wool, as described, for example, in applications EP 0465310 or EP 0439385, typically uses a series of centrifugal wheels, which are fed with the molten material to be fiberized via a distribution device. At the centrifuge outlet, the filaments are stretched by a high-temperature, high-velocity gas stream and carried toward a receiving device to form a fiber layer (or mineral wool).

[0003] In order to ensure that the fibers are held together and provide cohesion to the web, a binder composition in the form of an aqueous solution containing a thermosetting resin is sprayed onto the fibers on their way from the outlet of the centrifugal device to the receiving element. The fiber layer coated with the binder is then subjected to a heat treatment at temperatures generally above 100°C or even 200°C in order to carry out the polycondensation of the resin and thus form a binder intended to ensure cohesion between the fibers and to impart the properties sought to the insulation product thus obtained, in particular dimensional stability, tensile strength, thickness recovery after compression and uniform color.

[0004] The adhesive composition is prepared shortly before its use by diluting the concentrated thermosetting resin with water and by adding various customary additives (coupling agents, anti-dust additives, hydrophobizing agents, catalysts).

[0005] Concentrated thermosetting resins must be storage-stable, i.e. they must retain their ability to be diluted with water when preparing the adhesive composition for as long as possible. Concentrated thermosetting resins are generally considered stable when they retain a dilutability of at least 1000% (addition of 9 volumes of water to 1 volume of resin gives a clear solution without permanent turbidity) after a storage period of at least 14 days at temperatures between 12 and 18°C.

[0006] Furthermore, from a regulatory point of view, the resin must be considered non-polluting, ie it should contain and should generate during its use the smallest possible amount of compounds that could be harmful to human health or the environment.

[0007] The most commonly used thermosetting resins are phenolic resins of the resol type. In addition to their good crosslinking ability under the above-mentioned thermal conditions, these resins are also soluble in water, have a good affinity for mineral fibers, especially glass fibers, and are relatively inexpensive.

[0008] Resol phenolic resins are obtained by the reaction of phenol with formaldehyde in an alkaline medium. They contain numerous methylol functionalities carried by aromatic rings, which form crosslinking sites upon dehydration and release of formaldehyde (formol). This reaction is usually incomplete to ensure that the resulting resin remains dilutable. These resins are therefore essentially composed of phenol / formaldehyde (PF) condensates, residual phenolic compounds, and residual formaldehyde compounds. Residual phenolic compounds pose toxicity concerns. To address this, excess formaldehyde is conventionally used, typically with a formaldehyde / phenol molar ratio of between 2 and 4, allowing each phenol molecule to react with potentially three formaldehyde molecules.

[0009] The resulting resin thus contains non-negligible amounts of residual formaldehyde, which not only contributes to the stability of the resin but also presents regulatory problems of its own.

[0010] In order to reduce the amount of residual formaldehyde without adversely affecting the storage stability of the resin, EP 0 148 050 first proposed the addition of urea during the resin formation process. This resulted in the production of phenol-formaldehyde-urea resins and further by-products, namely monomethylurea, dimethylurea and trimethylurea, as well as urea-formaldehyde condensates. However, these condensates are thermally unstable in acidic media, i.e., in adhesive compositions, and therefore tend to release formaldehyde during curing. They also adversely affect the dilutability of the resin.

[0011] Several years ago, the applicant proposed improved resol phenolic resins, hereinafter equivalently referred to as "amino resins" or "aminophenol resins", which are storage-stable and substantially free of urea-formaldehyde (UF) resins.

[0012] These aminophenol resins are water-soluble resins that are stable at acidic pH, even at very acidic pH between 1 and 2. This good stability is achieved by means of an additional reaction step which consists of reacting the resol resin consisting essentially of a phenol / formaldehyde condensate, phenol and formaldehyde, with an amine, preferably a monoalkanolamine, and in particular monoethanolamine, or an amino acid, preferably glycine.

[0013] This alkanolamine reacts with a phenol / formaldehyde (PF) condensate and with residual phenol and formaldehyde according to the Mannich reaction to form a phenol / formaldehyde / amine (PFA) condensate. At the end of the reaction, the reaction mixture can be acidified, which does not lead to polymerization at ambient temperature. These amine resols are disclosed in WO 2008 / 043960 and WO 2008 / 043961 and are further distinguished by the absence of urea-formaldehyde condensate.

[0014] However, the applicant has observed that in the stabilized resol, the phenol-formaldehyde oligomers formed during the synthesis of the resol are found, i.e. bis-4-diphenyl tetramethylol, and cause forming sediment in the pipeline of conveying this adhesive composition and in the storage tank of this composition. This phenomenon needs to maintain the production line, and this produces unacceptable cost. Therefore can in the resol containing amine, add up to 25 % by weight after reacting with the monoalkanolamine, cooling the reaction mixture and acidifying, preferably urea between 10 % by weight to 20 % by weight, these amounts are represented with respect to the gross dry weight of the amine resol. Urea mainly serves as a solubilizing agent then, and makes it possible to further reduce the cost of the adhesive composition obtained and the product.

[0015] Amine-containing phenolic resins in aqueous solution stabilized with urea (solubilizer) have thus been used by the applicant for more than ten years for the manufacture of insulation products based on mineral or organic fibers, which release very low amounts of formaldehyde during production and during use.

[0016] The only drawback of these resins is the formation of ammonia (NH3), a thermal degradation product of urea, during the heat curing step at the production site and, in some applications, also during use. However, certain regulations are very strict when it comes to ammonia emissions from insulation products, particularly those required for M1 certification in Scandinavian countries.

[0017] In order to combat this phenomenon, it has been suggested to add cosolvents to the adhesive formulations, which comprise water-soluble aromatic polyols such as resorcinol (WO 2022 / 003289), optionally in combination with small amounts of urea.

[0018] After extensive research, it became apparent to the applicant that certain formaldehyde scavengers disclosed in WO 2009 / 136105 are capable of preventing the precipitation of bis-4-diphenyltetrakis without adversely affecting the dilutability of the resulting resin and without causing significant ammonia emissions during processing of the resin, during curing of the adhesive or during use of the final product, such as insulation.

[0019] In document WO2009 / 136105, formaldehyde scavengers such as ethylene urea are added when formulating the adhesive composition, rather than immediately after resin synthesis. In addition, the applicant has demonstrated that most of the formaldehyde scavengers mentioned in document WO2009 / 136105 do not dissolve bis-4-diphenyltetrakis. SUMMARY OF THE INVENTION Some urea derivatives, including ethylene urea, have been found to be excellent co-solvents because they: - is capable of stabilizing aqueous solutions of aminophenol-formaldehyde resins at least as effectively as urea, in that the composition remains more than 1000% dilutable and free of precipitates for at least 14 days, - they release almost no ammonia when subjected to the curing temperatures of resol resins, i.e. generally between 180 and 230°C, - are not classified as carcinogenic, mutagenic or reprotoxic (CMR) chemicals; and - Available to industry at an acceptable price.

[0021] The object of the present invention is therefore a stabilized resol resin comprising: (a) water, (b) amine-containing phenolic resins, and (c) Urea derivatives of formula (I): R3R4-N-CO-N-R1R2(I) in: R1 is a hydrogen atom or a linear or branched C1-C6 alkyl group, R2 is a hydrogen atom or a linear or branched C1-C6 alkyl group, or together with R4 and the nitrogen atom to which they are bonded, forms a 5- or 6-membered heterocyclic ring, R3 is a hydrogen atom, a linear or branched C1-C6 alkyl group, or a linear or branched C1-C6 hydroxyalkyl group, R4 is a linear or branched C1-C6 alkyl group or a linear or branched C1-C6 hydroxyalkyl group, or together with R2 and the nitrogen atom to which they are bonded, forms a 5- or 6-membered heterocyclic ring, The stabilized resol resin has a dry matter content of between 40 and 70% by weight.

[0022] Another object of the present invention is an adhesive composition prepared by diluting the stabilized resol resin and adding conventional additives. This adhesive composition thus comprises (dilution) water, the stabilized resol resin defined above, and one or more additives selected from coupling agents, oils, hydrophobizing agents, and curing reaction accelerators, and contains 0 to 5% by weight of urea, relative to the dry weight of the adhesive composition.

[0023] Another subject of the present invention is the use of the stabilized resol resin defined above for preparing an adhesive composition.

[0024] Another object is a method for stabilizing an amine resole resin, comprising adding at least one urea derivative as defined above to said resin within a period of time ranging from 1 minute to 12 hours, preferably from 1 minute to 2 hours, after the resin has been synthesized and cooled to below 30° C. The addition is preferably carried out in the reactor in which the resin is located after synthesis.

[0025] Finally, the object of the present invention is a method for manufacturing an insulation product based on mineral or organic fibers, comprising: - applying the binder composition to mineral fibers or organic fibers, preferably mineral fibers, and - heating the fibers coated with the binder composition to evaporate the volatile phase of the binder composition and to effect thermal curing of the non-volatile residue, or packaging the mineral fibers or organic fibers coated with the binder composition for their storage and / or transportation, And an insulation product obtained by this method, wherein the organic or mineral fibers are bound together by an insoluble and infusible adhesive obtained by solidification of the ingredients of the adhesive composition.

[0026] Details Throughout this description of the present invention, it is important to distinguish: - amine-containing phenolic resins obtained by condensation of phenol, formaldehyde and amines in alkaline medium and which do not contain urea-formaldehyde condensates (UF), - a stabilized resol containing an amine-containing phenolic resin, water and a solubilizer according to the invention, and - Adhesive compositions prepared by diluting stabilized resol resins and adding known additives.

[0027] Stabilized resol resins are therefore concentrated resins resulting from the synthesis which are to be stored, transported, sold and used as thermosetting components for the preparation of adhesive compositions.

[0028] The stabilized resol resin advantageously contains: - 75 to 99% by weight, preferably 80 to 97% by weight, in particular 90 to 97% by weight, of an amine-containing phenolic resin, and - 1 to 25% by weight, preferably 3 to 20% by weight, in particular 3 to 10% by weight, of urea derivatives of the formula (I), These percentages are based on the total dry weight of the stabilized resole resin.

[0029] For example, in the case of ethylene urea, a weight ratio of 6 to 10%, still better 7 to 9% is preferred. In the case of 1-(2-hydroxyethyl)-2-imidazolidinone (or HEI), a weight ratio of 1 to 5%, preferably 2 to 4%, is advantageously used.

[0030] The dry matter content of the stabilized resol resin is between 40 and 70% by weight, preferably between 45 and 65% by weight, and in particular between 50 and 60% by weight.

[0031] The expression "urea derivatives of formula (I)" used to describe the solubilizing agent includes both the compounds used individually as well as mixtures of two or more of these compounds.

[0032] The resin also contains small amounts of salts resulting from the neutralization of the catalyst (a strong base such as NaOH or KOH) with an acid such as sulfamic acid at the end of the resin synthesis.

[0033] The adjective "stabilized" with respect to the resol resin means, in the present invention, that the resin remains in the form of a clear solution free of precipitates when stored at a temperature of 12 to 18° C. for at least 14 days from the date of its synthesis and that it remains at least 1000% dilutable in water during this period.

[0034] The solubilizers used in the present invention to at least partially replace the urea used hitherto are selected from urea derivatives of formula (I), which are preferably not classified as carcinogenic, mutagenic or reprotoxic (CMR) chemicals. The list of CMR chemical compounds is the list specified in Annex VI to EC Regulation No. 1272 / 2008.

[0035] Typically, these derivatives are soluble in the amine resol resin, ie, their solubility in the resin at 12° C. is greater than 30 g / L, preferably greater than 50 g / L.

[0036] The urea derivatives used according to the invention correspond to formula (I): R3R4-N-CO-N-R1R2(I) in: R1 is a hydrogen atom or a linear or branched C1-C6 alkyl group, R2 is a hydrogen atom or a linear or branched C1-C6 alkyl group, or together with R4 and the nitrogen atom to which they are bonded, forms a 5- or 6-membered heterocyclic ring, R3 is a hydrogen atom, a linear or branched C1-C6 alkyl group, or a linear or branched C1-C6 hydroxyalkyl group, R4 is a linear or branched C1-C6 alkyl group or a linear or branched C1-C6 hydroxyalkyl group, or forms a 5- or 6-membered heterocyclic ring together with R2 and the nitrogen atom to which they are bonded.

[0037] According to a preferred embodiment: R1 is a hydrogen atom or a linear or branched C1-C4 alkyl group, preferably hydrogen, methyl or ethyl, R2 is a hydrogen atom or a linear or branched C1-C4 alkyl group, or together with R4 and the nitrogen atom to which they are bonded form a 5- or 6-membered heterocyclic ring, preferably hydrogen, methyl or ethyl, or together with R4 and the nitrogen atom to which they are bonded form an imidazolidine ring.

[0038] R3 is a hydrogen atom, a linear or branched C1-C4 alkyl group or a linear or branched C1-C4 hydroxyalkyl group, preferably hydrogen, methyl, ethyl, hydroxymethyl or hydroxyethyl, R4 is a linear or branched C1-C4 alkyl group, or together with R2 and the nitrogen atom to which they are bonded form a 5- or 6-membered heterocyclic ring, preferably a methyl group or an ethyl group, or together with R2 and the nitrogen atom to which they are bonded form an imidazolidine ring.

[0039] More preferably, the urea derivative of formula (I) is such that each linear or branched C1-C6 alkyl group is methyl and / or R1 = H.

[0040] Examples of urea derivatives of formula (I) are: ethylene urea, 2-hydroxyethyl urea, dimethyl urea, methyl urea, trimethylene urea, 1-(2-hydroxyethyl)-2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, and mixtures thereof. Ethylene urea, dimethyl urea, or 1-(2-hydroxyethyl)-2-imidazolidinone, more preferably 1-(2-hydroxyethyl)-2-imidazolidinone (or HEI) is preferred.

[0041] The addition of urea to the resol is in principle superfluous, and the stabilized resol according to the invention is therefore preferably free of urea.

[0042] However, for cost reasons, it may be useful to add urea to the resol to be stabilized. In this case, the amount of urea will be selected in small amounts to ensure that there is no significant emission of ammonia (NH3) during the thermal curing step of the adhesive and during the use of the manufactured insulation product. This addition can be made before, after, or simultaneously with the addition of the solubilizer, but must be performed after the synthesis of the amine-containing phenolic resin, which essentially consists of PF and PFA condensates, has been completed, i.e., after the reaction solution has been cooled and neutralized. It is indeed necessary to prevent the formation of urea-formaldehyde condensates during the resin synthesis.

[0043] When urea and the solubilizer according to the invention are used simultaneously, the stabilized resol resin (amine-containing phenolic resin + solubilizer + urea) advantageously contains less than 10% by weight, for example 0.5 to 10% by weight, in particular less than 5% by weight, for example 1 to 5% by weight, of urea, relative to the total dry weight of the resin.

[0044] The phenolic resins used in the present invention contain basic (protonatable) amine functions and are stable in acidic media.

[0045] These amine-functional phenolic resins are known, and their preparation is described in detail in the applicant's applications WO 2008 / 043960 and WO 2008 / 043961. They consist essentially of phenol / formaldehyde (PF) condensates and phenol / formaldehyde / amine (PFA) condensates and are distinguished in particular by the absence of urea-formaldehyde (UF) condensates. As explained in the introduction, these urea-formaldehyde condensates are present in large quantities in many other phenolic resins of the prior art and have insufficient thermal stability, releasing formaldehyde and ammonia upon thermal decomposition.

[0046] The stabilized resol resin of the present invention advantageously has a pH between 1.0 and 6.5, preferably between 1.5 and 5.5, more preferably between 1.6 and 5.0.

[0047] The adhesive composition prepared by diluting the stabilized resol phenolic resin with water generally has a pH lower in acidity than the resol phenolic resin, generally between 3 and 7, particularly between 3.5 and 6.5, which is beneficial for preventing corrosion of equipment used to manufacture insulation products. The dilution water used to prepare the adhesive composition from the stabilized resol phenolic resin may be partially derived from wash water recycled from the equipment used to manufacture insulation products.

[0048] The adhesive composition of the present application therefore contains water, a stabilized resole phenolic resin and one or more additives customary in the field of mineral wool-based insulation products.

[0049] These additives are particularly selected from coupling agents, particularly functional silanes such as aminosilanes or epoxysilanes, oils, particularly mineral oils, hydrophobizing agents such as reactive or non-reactive polyorganosiloxanes (silicones), and curing reaction accelerators (catalysts). Furthermore, the adhesive composition may contain 0 to 5% by weight of urea. Preferably, it is urea-free.

[0050] When applied to the fibers, the adhesive composition preferably has a solids content of between 2 and 25% by weight, preferably between 3 and 15% by weight. It therefore contains 75 to 98% by weight, in particular 85 to 97% by weight, of water.

[0051] The adhesive composition is applied in such an amount that the content of insoluble and infusible adhesive in the final product obtained after thermal curing is between 2% and 20% by weight, preferably between 3% and 15% by weight, in particular between 4 and 12% by weight.

[0052] Another subject of the present invention is a method for producing an insulation product based on mineral fibers or organic fibers. This method comprises the following successive steps: - applying the binder composition according to the invention to mineral or organic fibers, preferably mineral fibers, and - heating the fibers coated with the binder composition to evaporate the volatile phase of the binder composition and to effect thermal curing of the non-volatile residue, or packaging the mineral or organic fibers coated with the binder composition for their storage and / or transportation.

[0053] The mineral fibers are advantageously selected from mineral wool fibers, in particular glass wool or rock wool.

[0054] When the insulation product is based on mineral wool, the binder composition is projected onto the mineral fibers by spraying at the outlet of the centrifugal device (fiberization) and before the mineral fibers are collected in the form of a fibrous layer on a receiving element (forming). This fibrous layer is then treated in an oven at a temperature that allows the reactive components to crosslink and form an infusible binder (curing). This crosslinking / thermosetting step is carried out by heating at a temperature greater than or equal to 180°C, preferably between 190°C and 220°C, for a duration of between 20 seconds and 300 seconds, preferably between 30 and 250 seconds.

[0055] When the insulation product is based on organic fibers, such as fibers of plant origin, for example cellulose fibers, or fibers of animal origin, such as wool, the curing temperature is generally lower than that used for curing products based on mineral fibers, in order to protect the organic fibers from possible thermal degradation. The curing temperature is, for example, between 120° C. and 200° C. The curing duration is generally between 1 minute and several tens of minutes, for example between 5 and 50 minutes, preferably between 5 and 30 minutes, and in particular between 5 and 15 minutes.

[0056] In the process of the invention, curing of the mineral or organic fibres may be carried out immediately after applying the binder composition to the fibres and collecting the sized fibres on a conveyor belt, for example by feeding into a temperature controlled oven at the desired curing temperature.

[0057] The method of the present application also encompasses an embodiment wherein the bonded fiber mat is not immediately cured, but rather packaged, such as partially dried, cut, compressed, formed, and wrapped, to separate the curing step from the bonded fiber mat manufacturing step.

[0058] The packaging material must be selected so as to allow storage and / or transport of these intermediate products (fibers sized with uncured binder) so that the additional process steps can be carried out subsequently or at a different location, and which include thermal curing of the binder composition, optionally after shaping the intermediate product, for example in a mold.

[0059] The packaging material is preferably a plastic film. Example

[0060] Synthesis of Unstabilized Resol Phenolic Resin 380 g of phenol (4 mol), 313 g of paraformaldehyde (10 mol) as a formaldehyde source and 367 g of water (paraformaldehyde / phenol molar ratio equal to 2.5) were introduced into a 2-liter reactor equipped with a condenser on top and a stirring system, and the mixture was heated to 45° C. with stirring.

[0061] 53.2 g of 50% sodium hydroxide solution (ie 7% by weight relative to the phenol) were then regularly added over a period of 30 minutes, and the temperature was then gradually increased to 70°C over 30 minutes and maintained for 80 minutes.

[0062] The temperature was then gradually lowered to 60°C over 30 minutes while 71.5 g of monoethanolamine (1.17 mol) was uniformly added to the reaction mixture. The temperature was maintained at 60°C for 15 minutes, the mixture was cooled to approximately 35°C over 30 minutes, and solid sulfamic acid was added over 1 hour until the pH reached 5.0. The pH was then lowered to 4.5 using a 15% sulfamic acid solution. If necessary, the solids content of the liquid resin was adjusted to 58% by weight with water.

[0063] The obtained resol has the appearance of a yellow-orange transparent liquid with a free formaldehyde content of less than or equal to 0.2%, preferably 0.1%, a free phenol content of less than or equal to 1%, preferably 0.5% (these contents are expressed relative to the total weight of the liquid), and a dilutability of greater than 2000%. This is referred to as an unstabilized resol.

[0064] Preparation of stabilized resol phenolic resin Immediately after its preparation, the unstabilized resol resin was divided into several batches, and to each batch was added the stabilizer to be tested in an amount equal to x parts by weight per 80 parts by dry weight of resin (see Table 1). Stirring was carried out at ambient temperature until complete dissolution was achieved, to obtain the so-called "stabilized" resol resin.

[0065] Dilutability The dilutability (or water resistance) of various resol phenolic resins over time was evaluated as follows: 10 mL of resin was poured into a 250 mL Erlenmeyer flask. 10 mL of water was added, the mixture was stirred, and the appearance of turbidity was verified. When the solution remained clear after 30 seconds, another 10 mL of water was added, the mixture was stirred, and the clarity of the solution was evaluated again. This cycle was repeated until permanent turbidity appeared. The dilutability was calculated as follows: Dilutability = (number of additions + 1) x 100 When 10 ml of water was added 19 times without turbidity appearing, the resin was considered to have a dilutability of 2000% and to be infinitely dilutable.

[0066] Crystallization stability To evaluate the crystallization stability of resol phenolic resins, 20 ml of resin were poured into glass tablet organizers, stored at 3°C, and checked at regular intervals for the presence or absence of crystals. A qualitative analysis was performed to compare the amount of precipitate and its formation kinetics with those obtained for a reference consisting of resin stabilized with 15 parts of urea. The smaller the amount and the slower the kinetics, the higher the number of "+" signs assigned to the sample. Similarly, the greater the amount of precipitate and the faster the kinetics, the higher the number of "-" signs assigned to the sample.

[0067] Free formaldehyde content The free formaldehyde content of the resol was also evaluated to verify the ability of the stabilizer to react with residual formaldehyde (formaldehyde scavenger functionality).

[0068] To do this, place approximately 1 g of resol in a 100 ml volumetric flask and accurately record the sample mass. m Distilled water was added to the mark. The free formaldehyde content was determined using a LANGE DR6000 colorimeter supplied with the LCK 325 formaldehyde quantification kit according to the manufacturer's instructions.

[0069] The measurement is performed on 1 ml of sample placed in the preparation flask. The result A obtained by the colorimeter is given in mg / l. The free formaldehyde content is calculated as follows: % Free Formaldehyde = (A x 0.1) / m x 100 Free formaldehyde content is given as a % of the sample and is expressed as ± 0.01%. Any result below 0.01% is expressed as <0.01%.

[0070] Ammonia emissions Finally, ammonia emissions from the curing of different resols were evaluated by performing pollution simulations in the laboratory. A resol solution corresponding to 1 gram of solids, pre-diluted to 30% solids, was introduced into a 1-liter flat-bottomed glass flask. The inlet of a sampler (dipper) was connected to the flat-bottomed flask to purge the sample surface with an air flow of 1 liter / minute. The assembly was placed in a ventilated oven at 120°C for 15 minutes, after which the temperature was increased to 215°C for 1 hour. The outlet of the sampler (dipper) was connected to three bubblers arranged in series outside the oven, each containing 100 ml of 0.02 N sulfuric acid solution. The contents of the bubblers were analyzed by ion chromatography to quantify the amount of ammonia captured after each temperature step. Two measurements were performed for each test batch.

[0071] The measurement results are summarized in Table 1 below for all substances tested as stabilizers, which are potential candidates for replacing urea, as well as for the reference urea and for various formaldehyde scavengers described in WO 2009 / 136105.

[0072] Of all the organic compounds evaluated, only the urea derivatives according to the invention have a stabilizing power on resols that is at least equal to or even greater than that of urea: at a content of urea derivative less than or equal to the amount of urea used, dilutabilities of greater than 1000% and crystallization stability for the same or longer periods of time are indeed observed.

[0073] A significant reduction in ammonia emissions was further noted when comparing these compounds to urea.

[0074] Furthermore, by B. Méchin et al. Eur. Polym. J. Vol. 22, No. 2, pp. 115-124 (1986) and Eur. Polym. J. The precipitate formed in the presence of urea and the urea derivative according to the present invention was analyzed using the method described in Vol. 20, No. 4, pp. 333-341 (1984). The precipitate was subjected to HPLC analysis using a chromatograph equipped with a UV detector at 280 nm or coupled to a negative-scan mass spectrometer (m / z = 319). The resulting chromatogram was compared with the chromatogram of a bis-4-diphenyltetrakisolmethyl sample (control) obtained by preparative chromatography. This confirmed that the precipitate observed in the case of urea (control sample) and 4 wt% 1-(2-hydroxyethyl)-2-imidazolidinone (sample according to the present invention) indeed corresponded to bis-4-diphenyltetrakisolmethyl, as the UV chromatograms and the control chromatograms were superimposable, and the mass spectrometry chromatograms of the sample according to the present invention and the control sample (with the specific extracted ion 319) exhibited the same peaks as the control and at the same retention times as the UV chromatograms.

Claims

1. A stabilized resol resin comprising - water - amine-containing phenolic resins, and - Urea derivatives of formula (I): R3R4-N-CO-N-R1R2 (I) in: R1 is a hydrogen atom or a linear or branched C1-C6 alkyl group, R2 is a hydrogen atom or a linear or branched C1-C6 alkyl group, or together with R4 and the nitrogen atom to which they are bonded, forms a 5- or 6-membered heterocyclic ring, R3 is a hydrogen atom, a linear or branched C1-C6 alkyl group, or a linear or branched C1-C6 hydroxyalkyl group, R4 is a linear or branched C1-C6 alkyl group or a linear or branched C1-C6 hydroxyalkyl group, or together with R2 and the nitrogen atom to which they are bonded, forms a 5- or 6-membered heterocyclic ring, The stabilized resol resin has a dry matter content of between 40 and 70% by weight.

2. The stabilized resol resin according to claim 1, wherein It contains: - 75 to 99% by weight, preferably 80 to 97% by weight, in particular 90 to 97% by weight, of an amine-containing phenolic resin, - 1 to 25% by weight, preferably 3 to 20% by weight, in particular 3 to 10% by weight, of urea derivatives of the formula (I), These percentages are relative to the total dry weight of the stabilized resole resin.

3. The stabilized resol resin according to claim 1 or 2, characterized in that The urea derivative of formula (I) is such that: R1 is a hydrogen atom or a linear or branched C1-C4 alkyl group, preferably hydrogen, methyl or ethyl, R2 is a hydrogen atom or a linear or branched C1-C4 alkyl group, or together with R4 and the nitrogen atom to which they are bonded, forms a 5- or 6-membered heterocyclic ring, preferably hydrogen, methyl or ethyl, or together with R4 and the nitrogen atom to which they are bonded, forms an imidazolidine ring, R3 is a hydrogen atom, a linear or branched C1-C4 alkyl group or a linear or branched C1-C4 hydroxyalkyl group, preferably hydrogen, methyl, ethyl, hydroxymethyl or hydroxyethyl, R4 is a linear or branched C1-C4 alkyl group, or together with R2 and the nitrogen atom to which they are bonded form a 5- or 6-membered heterocyclic ring, preferably a methyl group or an ethyl group, or together with R2 and the nitrogen atom to which they are bonded form an imidazolidine ring.

4. The stabilized resol resin according to any one of claims 1 to 3, characterized in that The urea derivative of formula (I) is selected from the group consisting of ethylene urea, 2-hydroxyethyl urea, dimethyl urea, methyl urea, trimethylene urea, 1-(2-hydroxyethyl)-2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone and mixtures thereof, preferably ethylene urea, dimethyl urea or 1-(2-hydroxyethyl)-2-imidazolidinone.

5. The stabilized resol resin according to any one of the preceding claims, characterized in that It does not contain urea.

6. Stabilized resol resin according to any one of the preceding claims, characterized in that The amine-containing phenolic resin is essentially composed of phenol-formaldehyde condensate and phenol-formaldehyde-amine condensate.

7. An adhesive composition comprising water, a stabilized resol phenolic resin according to any one of the preceding claims and one or more additives selected from coupling agents, oils, hydrophobizing agents and curing reaction accelerators, characterized in that It comprises 0 to 5% by weight of urea relative to the dry weight of the adhesive composition, and is preferably urea-free.

8. The adhesive composition according to claim 7, characterized in that It contains 75 to 98% by weight of water.

9. A method for stabilizing an amine resol resin, which comprises adding to said resin at least one urea derivative as defined in any one of claims 1, 3 or 4 within a period of 1 minute to 12 hours, preferably 1 minute to 2 hours, after synthesis of the resin and cooling thereof to below 30°C.

10. Use of the stabilized resol phenolic resin according to any one of claims 1 to 6 for preparing an adhesive composition.

11. A method of manufacturing an insulation product based on mineral fibers or organic fibers, comprising: - applying the adhesive composition according to any one of claims 7 to 8 to mineral fibers or organic fibers, preferably mineral fibers, and - heating the fibers coated with the binder composition to evaporate the volatile phase of the binder composition and to effect thermal curing of the non-volatile residue, or packaging the mineral or organic fibers coated with the binder composition for their storage and / or transportation.

12. The method according to claim 11, characterized in that The mineral fibers are selected from mineral wool fibers, in particular glass wool or rock wool.

13. An insulation product based on mineral or organic fibers, obtainable by the process according to any one of claims 11 and 12.

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