Resol resin stabilized by urea derivatives

Abstract

The present invention relates to an amine resin stabilized by a solubilizer selected from specific urea derivatives, a binder composition produced from the resin, a method for producing a fiber-based insulating article using the binder composition, particularly a method for producing a mineral wool-based insulating article, and a heat-insulating article and / or sound-insulating article obtained by the above production method.

Description

Technical Field

[0001] The present invention relates to an amine resin stabilized by a solubilizing agent selected from specific urea derivatives, a binder composition produced from the resin, a method for producing a fiber-based barrier article (insulating article) using the binder composition, particularly a method for producing a barrier article based on mineral wool, and a heat-insulating and / or sound-insulating article obtained by the production method.

Background Art

[0002] The production of barrier articles based on mineral wool generally includes the production process of the wool itself, which can be carried out by various methods, for example, according to known techniques for fiber generation by internal or external centrifugation. Internal centrifugation consists of introducing a molten inorganic material (glass or rock) into a centrifuge with a large number of micro-orifices, injecting the material towards the peripheral wall of the device by the action of centrifugal force, and separating it into filaments. The external centrifugation method, which is relatively suitable for rock wool, typically uses a cascade of centrifugal wheels supplied with a molten material to be fiberized by a distribution device, as described, for example, in European Patent Application Publication No. 0465310 or European Patent Application Publication No. 0439385. At the outlet of the centrifuge, the filaments are stretched and guided towards a receiving device by a high-temperature and high-speed gas stream to form a fiber layer (or mineral wool).

[0003] To ensure that the fibers are drawn together and to provide cohesiveness to the web, a binder composition in the form of an aqueous solution containing a thermosetting resin is sprayed onto the fibers along the path from the centrifuge outlet to the receiver. The fiber layer coated with the binder is then subjected to heat treatment at a temperature generally above 100°C, or even above 200°C, thereby causing a polycondensation reaction of the resin, thus forming a binder intended to ensure cohesiveness between the fibers and to impart desired properties to the resulting barrier article, particularly dimensional stability, tensile strength, thickness recovery after compression, and uniform color.

[0004] Binder compositions are produced immediately before use by diluting concentrated thermosetting resin with water and adding various commonly used additives (coupling agents, dust suppressants, hydrophobic agents, catalysts).

[0005] Concentrated thermosetting resins must have storage stability; that is, they must maintain their ability to be diluted with water during binder composition preparation for as long as possible. Concentrated thermosetting resins are generally considered stable if they maintain at least 1000% dilutability (a clear solution without permanent turbidity is obtained by adding 9 volumes of water to 1 volume of resin) after being stored at a temperature of 12-18°C for at least 14 days.

[0006] Furthermore, from a regulatory standpoint, resins must be considered non-contaminating, meaning that the amount of compounds they contain—and the amount they generate when used—that could be harmful to human health or the environment must be as minimal as possible.

[0007] The most commonly used thermosetting resins are resol-based phenolic resins. In addition to their good crosslinking ability under the aforementioned thermal conditions, these resins are water-soluble, have good affinity with inorganic fibers, especially glass fibers, and are relatively inexpensive.

[0008] Resol resins are obtained by reacting phenol with formaldehyde in a basic medium. These contain numerous methylol groups supported by aromatic rings, which constitute crosslinking sites due to dehydration / formaldehyde release. Since this reaction is generally incomplete, the resulting resins remain dilutable. Therefore, these resins essentially consist of phenol / formaldehyde (PF) condensates, residual phenol compounds, and residual formaldehyde compounds. Residual phenol compounds pose a toxicity problem. To address this, excess formaldehyde is conventionally used, with a formaldehyde / phenol molar ratio typically between 2 and 4, where each molecule of phenol can potentially react with three molecules of formaldehyde.

[0009] Therefore, the resulting resin contains a non-negligible amount of residual formaldehyde, which contributes to the stability of the resin but also poses regulatory problems in itself.

[0010] To reduce residual formaldehyde without adversely affecting the storage stability of the resin, the addition of urea during resin formation was first proposed in European Patent Application Publication No. 0148050. This leads to the formation of phenol-formaldehyde-urea resin, as well as additional by-products, namely mono, di, and trimethylol ureas, and urea-formaldehyde condensates. However, these condensates are thermally unstable in acidic media, i.e., binder 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 resins, hereinafter referred to as "amino resins" or "aminophenol resins," which are storage stable and essentially free of urea-formaldehyde (UF) resins.

[0012] These aminophenol resins are water-soluble resins and are stable at acidic pH levels, even at very strong acidic pH levels of 1-2. This good stability is obtained thanks to an additional reaction step, which involves reacting a resol, essentially consisting of a phenol / formaldehyde condensate, phenol, and formaldehyde, with an amine, preferably a monoalkanolamine, particularly a monoethanolamine, or an amino acid, preferably glycine.

[0013] These alkanolamines react with phenol / formaldehyde (PF) condensates and residual phenol and formaldehyde according to the Mannich reaction to form phenol / formaldehyde / amine (PFA) condensates. At the end of the reaction, the reaction mixture can be acidified without undergoing polymerization at room temperature. These amine resoles are disclosed in International Publications 2008 / 043960 and 2008 / 043961 and are further characterized by not containing urea-formaldehyde condensates.

[0014] However, the applicant observed that phenol-formaldehyde oligomers, namely bis-4-diphenyltetramethylol, formed during the synthesis of phenolic resins, were found in the stabilized resol resins, leading to the formation of precipitates in the pipes carrying the binder composition and in the storage tanks for this composition. This phenomenon necessitates maintenance of the production line, which incurs unacceptable costs. Therefore, after the reaction of the amine-containing phenolic resin with a monoalkanolamine, cooling of the reaction mixture, and acidification, up to 25% by weight, preferably 10% to 20% by weight, of urea may be added, the amount being expressed relative to the total dry weight of the amine resol. The urea then primarily functions as a solubilizer, allowing for further reduction of the cost of the binder composition and the resulting articles.

[0015] Thus, amine-containing phenolic resins in aqueous solutions stabilized by urea (a solubilizer) have been used by the applicant for over 10 years in the manufacture of barrier articles based on inorganic or organic fibers that release extremely low amounts of formaldehyde during production and use.

[0016] The only drawback of these resins is that ammonia (NH3), a thermal decomposition product of urea, is formed during the thermosetting process at the production site and also when used in some applications. However, certain regulations, particularly the M1 certification requirements in Scandinavian countries, are very strict regarding ammonia emissions from barrier products.

[0017] To address this phenomenon, it has been proposed to add a cosolvent containing a water-soluble aromatic polyol, such as resolcinol, to the binder composition in combination with a small amount of urea as desired (International Publication No. 2022 / 003289).

[0018] After extensive research, the applicant has found that certain formaldehyde scavengers disclosed in International Publication No. 2009 / 136105 can prevent the precipitation of bis-4-diphenyltetramethylol, and these do not adversely affect the dilutability of the resulting resin or cause significant ammonia release during resin processing, i.e., during binder curing or use of the final product (such as a barrier (insulator)).

[0019] International Publication 2009 / 136105 describes how formaldehyde scavengers, such as ethylene urea, are added when the binder composition is formed, rather than immediately after resin synthesis. Furthermore, the applicant demonstrated that bis-4-diphenyltetramethylol is not solubilized by most of the formaldehyde scavengers described in International Publication 2009 / 136105. [Overview of the Initiative] [Problems that the invention aims to solve]

[0020] Some urea derivatives, such as ethyleneurea, have been found to be excellent cosolvents in the following respects: - It has the ability to stabilize an aqueous solution of aminophenol-formaldehyde resin with at least the same efficiency as urea, that is, the composition maintains a dilution ratio of over 1000% and does not produce precipitate for at least 14 days. - They essentially do not release ammonia even when exposed to the curing temperature of resol resins, which is typically 180-230°C. - Not classified as a carcinogenic chemical, mutagenic chemical, or reproductive toxic (CMR) chemical, and - It is available at an acceptable price for industrial use. [Means for solving the problem]

[0021] As a result, the object of the present invention is a stabilized resol resin comprising the following: (a) Water, (b) Amine-containing phenolic resin, and (c) Urea derivatives of formula (I): R3R4-N-CO-N-R1R2(I) Here: 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, they form a 5-membered or 6-membered heterocycle. R3 is a hydrogen atom, a linear or branched C1-C6 alkyl group, or a linear or branched C1-C6 hydroxylalkyl 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, they form a 5-membered or 6-membered heterocycle. The stabilized resol resin has a dry substance content of 40-70% by weight.

[0022] Another object of the present invention is a binder composition produced by diluting a stabilized resol resin and adding common additives. Thus, this binder composition contains (diluted) water, the aforementioned stabilized resol resin, 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 based on the dry weight of the binder composition.

[0023] A further object of the present invention is the use of the aforementioned stabilized resol resin for the production of a binder composition.

[0024] A further object is a method for stabilizing an amine resol resin, which comprises adding at least one of the aforementioned urea derivatives to the resin within 1 minute to 12 hours, preferably within 1 minute to 2 hours, following its synthesis and cooling to below 30°C. The addition is preferably carried out in the reactor in which the resin is present after synthesis.

[0025] Finally, an object of the present invention is a method for manufacturing a barrier article based on inorganic or organic fibers, comprising the following: - applying a binder composition to inorganic or organic fibers, preferably inorganic fibers; - heating the fibers coated with the binder composition, thereby evaporating the volatile phase of the binder composition and thermally curing the non-volatile residue, or packing the inorganic or organic fibers coated with the binder composition for storage and / or transportation purposes; and a manufacturing method comprising the above, and a barrier article obtained by this method, wherein the organic or inorganic fibers are joined together by an insoluble and infusible binder obtained by curing the components of the binder composition.

Embodiments for Carrying Out the Invention

[0026] Throughout the description of the present invention, it is important to distinguish the following: - Amine-containing phenolic resin, obtained by condensing phenol, formaldehyde, and amine in a basic medium, and free from urea-formaldehyde (UF) condensate, - A stabilized resol resin containing an amine-containing phenol resin, water, and a solubilizer according to the present invention, - A binder composition, which is produced by diluting a stabilized resol resin and adding known additives.

[0027] Therefore, stabilized resol resins are concentrated resins obtained by synthesis, which are stored, transported, sold, and used as thermosetting components for the production of binder compositions.

[0028] Stabilized resol resins have the advantage of, - 75-99% by weight, preferably 80-97% by weight, particularly 90-97% by weight, of an amine-containing phenolic resin, and - Contains 1 to 25% by weight, preferably 3 to 20% by weight, and particularly 3 to 10% by weight, a urea derivative of formula (I), These proportions are based on the total dry weight of the stabilized resol resin.

[0029] In the case of ethylene urea, for example, 6-10% by weight is preferred, and more preferably 7-9%. In the case of 1-(2-hydroxyethyl)-2-imidazolidinone (or HEI), 1-5% by weight, preferably 2-4%, is advantageously used.

[0030] The dry substance content of the stabilized resol resin is 40-70% by weight, preferably 45-65% by weight, and particularly 50-60% by weight.

[0031] The expression "urea derivative of formula (I)" used to describe solubilizers includes both compounds used alone and mixtures of two or more of these compounds.

[0032] Furthermore, at the end of the resin synthesis process, the resin contains a small amount of salt resulting from the neutralization of the catalyst (a strong base, such as NaOH or KOH) by an acid, such as sulfamic acid.

[0033] In this invention, the adjective "stabilized" in relation to resol resin means that the resin maintains a clear, precipitate-free solution form at a temperature of 12-18°C for at least 14 days from its synthesis, and during this period maintains at least 1000% dilutability in water.

[0034] In the present invention, the solubilizer used to at least partially replace conventionally used urea is selected from urea derivatives of formula (I), which are preferably not carcinogenic, mutagenic, or reproductive toxic (CMR) chemicals. A list of CMR chemicals is provided in Annex VI of EC Regulation 1272 / 2008.

[0035] Generally, these derivatives are soluble in amine resins, meaning they have a solubility in the resin at 12°C of more than 30 g / L, preferably more than 50 g / L.

[0036] The urea derivative used in the present invention corresponds to formula (I): R3R4-N-CO-N-R1R2(I) Here: 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, they form a 5-membered or 6-membered heterocycle. R3 is a hydrogen atom, a linear or branched C1-C6 alkyl group, or a linear or branched C1-C6 hydroxylalkyl 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, they form a 5-membered or 6-membered heterocycle.

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

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

[0040] Examples of urea derivatives of formula (I) include: ethyleneurea, 2-hydroxyethylurea, dimethylurea, methylurea, trimethyleneurea, 1-(2-hydroxyethyl)-2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, and mixtures thereof. Ethyleneurea, dimethylurea, or 1-(2-hydroxyethyl)-2-imidazolidinone are preferred, and more preferably 1-(2-hydroxyethyl)-2-imidazolidinone (or HEI).

[0041] In principle, the addition of urea to resol resins is unnecessary, and therefore, the stabilized resol resin of the present invention preferably does not contain urea.

[0042] However, for cost reasons, it may be useful to add urea to the stabilized resol resin. In this case, a small amount of urea is selected to ensure that no significant ammonia (NH3) release occurs during the thermal curing process of the binder and when using the resulting barrier article. This addition can be done before, after, or simultaneously with the addition of the solubilizer, but it must be done after the synthesis of the amine-containing phenolic resin, which essentially consists of PF condensates and PFA condensates, is complete, i.e., after the reaction solution has cooled and been neutralized. In fact, it is necessary to prevent the formation of urea-formaldehyde condensates during resin synthesis.

[0043] When both urea and the solubilizer according to the present invention are used, the resin preferably contains less than 10% by weight of urea, for example 0.5 to 10% by weight, and especially less than 5% by weight, for example 1 to 5% by weight, based on the total dry weight of the stabilized resol resin (amine-containing phenolic resin + solubilizer + urea).

[0044] The phenolic resin used in the present invention contains a basic (protonable) amine functional group and is stable in an acidic medium.

[0045] These phenolic resins containing amine functional groups are known, and their formation is described in detail in the applicant's International Publications 2008 / 043960 and 2008 / 043961. These are characterized in that they essentially consist of phenol / formaldehyde (PF) condensates and phenol / formaldehyde / amine (PFA) condensates, and are particularly characterized by the absence of urea-formaldehyde (UF) condensates. As described in the introduction, these urea-formaldehyde condensates are present in large quantities in many other phenolic resins of the prior art, have poor thermal stability, and release formaldehyde and ammonia upon thermal decomposition.

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

[0047] The binder composition produced by diluting a stabilized resol resin with water generally has a less acidic pH than the resol resin, typically 3 to 7, and especially 3.5 to 6.5, which is advantageous for preventing corrosion in barrier article manufacturing equipment. The dilution water used to produce the binder composition from the stabilized resol resin may be derived from a portion of the wash water recycled from the barrier article manufacturing equipment.

[0048] Therefore, the binder composition of this application contains water, a stabilized resol resin, and one or more additives commonly used in the field of barrier articles based on mineral wool.

[0049] These additives are selected from, among other things, coupling agents, particularly functional silanes, such as aminosilanes or epoxysilanes; oils, particularly mineral oils; hydrophobic agents, such as reactive or non-reactive polyorganosiloxanes (silicones); and curing reaction accelerators (catalysts). Furthermore, the binder composition may contain 0 to 5% by weight of urea. Preferably, it does not contain urea.

[0050] At the time of application to the fibers, the binder composition preferably has a solids content of 2-25% by weight, and particularly preferably 3-15% by weight. Therefore, it contains 75-98% by weight, and particularly 85-97% by weight, of water.

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

[0052] Another subject of the present invention is a method for manufacturing a barrier article based on inorganic or organic fibers. This method comprises the following sequence of steps: - Applying the binder composition according to the present invention to inorganic fibers or organic fibers, preferably inorganic fibers, and, - Heating fibers coated with a binder composition to evaporate the volatile phase of the binder composition and cause the non-volatile residue to heat-set, or packaging inorganic or organic fibers coated with a binder composition for storage and / or transport purposes.

[0053] Inorganic fibers are advantageously selected from mineral wool fibers, particularly glass wool or rock wool.

[0054] If the barrier article is a mineral wool-based article, the binder composition is sprayed onto the inorganic fibers by atomization at the outlet of a centrifuge (fiberization), the inorganic fibers are then collected on a receiver in the form of a fiber layer (formation), and then processed in an oven at a temperature that allows for crosslinking of the reactive components and formation of an insoluble binder (curing). This crosslinking / thermosetting process is carried out by heating at a temperature of 180°C or higher, preferably 190°C to 220°C, for 20 to 300 seconds, preferably 30 to 250 seconds.

[0055] When the barrier article is based on organic fibers, such as plant-derived fibers, such as cellulose fibers, or animal-derived fibers, such as wool, the curing temperature is generally set lower than the temperature used for curing articles based on inorganic fibers, thereby protecting the organic fibers from potential thermal decomposition. The curing temperature is, for example, in the range of 120 to 200°C. The curing time is generally 1 minute to several tens of minutes, for example 5 to 50 minutes, preferably 5 to 30 minutes, and especially 5 to 15 minutes.

[0056] In the method of the present invention, curing of inorganic or organic fibers may be performed immediately after the application of the binder composition to the fibers and collection of the sizing-treated fibers onto a conveyor belt, for example, by passing them through an oven that is temperature-controlled at a desired curing temperature.

[0057] Furthermore, the method of this application also includes embodiments in which the bonded fiber mat is not immediately cured, but is packaged, for example, partially dried, cut, compressed, molded, and packaged, and a curing process separate from the manufacturing process of the bonded fiber mat is envisioned.

[0058] The packaging material should be selected to allow these intermediate articles (fibers sized with an uncured binder) to be stored and / or transported toward an additional process, which may be carried out subsequently or elsewhere and may include the thermocuring of the binder composition after the intermediate articles have been formed, for example, after molding in a mold.

[0059] The packaging material is preferably plastic film. [Examples]

[0060] Synthesis of unstabilized resol resins

[0061] 380 g (4 moles) of phenol, 313 g (10 moles) of paraformaldehyde used as a formaldehyde source, and 367 g of water (paraformaldehyde / phenol molar ratio equal to 2.5) are introduced into a 2-liter reactor equipped with a condenser at the top and a stirring system, and the mixture is heated to 45°C while stirring.

[0062] Then, 53.2 g of 50% sodium hydroxide solution (i.e., 7% by weight relative to phenol) is uniformly added over 30 minutes, and the temperature is then gradually increased to 70°C within 30 minutes and maintained for 80 minutes.

[0063] Then, gradually lower the temperature to 60°C over 30 minutes while uniformly adding 71.5 g of monoethanolamine (1.17 mol) to the reaction mixture. After maintaining the temperature at 60°C for 15 minutes, cool the mixture to approximately 35°C within 30 minutes, and add solid sulfamic acid within 1 hour until the pH equals 5.0. Subsequently, use a 15% sulfamic acid solution to lower the pH to 4.5. If necessary, adjust the solid weight content of the liquid resin to 58% with water.

[0064] The resulting resol resin has the appearance of a yellow-orange transparent liquid; it has a free formaldehyde content of 0.2% or less, preferably 0.1% or less, a free phenol content of 1% or less, preferably 0.5% or less (these contents are expressed relative to the total weight of the liquid), and a dilutability of more than 2000%. It is called an unstabilized resol resin.

[0065] Production of stabilized resol resin

[0066] The unstabilized resol resin is divided into several batches immediately after its production, and the stabilizer to be tested is added to each batch in an amount equal to x parts by weight per 80 parts dry weight of the resin (see Table 1). Stirring is carried out at room temperature until complete dissolution is achieved, thereby obtaining the so-called "stabilized" resol resin.

[0067] Dilutable

[0068] The dilution rate (or water resistance) of various resol resins over time is evaluated as follows: Pour 10 mL of resin into a 250 mL Erlenmeyer flask. Add 10 mL of water, stir the mixture, and check whether turbidity appears. If the solution remains clear after 30 seconds, add another 10 mL of water, stir the mixture, and re-evaluate the clarity of the solution. Repeat this cycle until permanent turbidity appears. Calculate the dilution rate using the following formula: Dilution ratio = (Number of additions + 1) × 100

[0069] If the resin does not become cloudy even after adding 10 mL of water 19 times, it is considered to have a dilutability of 2000% and can be diluted indefinitely.

[0070] crystal stability

[0071] To evaluate the crystalline stability of the resol resin, 20 mL of the resin is poured into a glass tablet formizer, stored at 3°C, and the presence or absence of crystals is checked periodically. Qualitative analysis is performed to compare the amount of precipitate and its formation rate with those obtained for a standard consisting of resin stabilized with 15 parts urea. The smaller the amount and the slower the formation rate, the higher the positive value assigned to the sample. Similarly, the larger the amount and the faster the formation rate, the higher the negative value assigned to the sample.

[0072] Free formaldehyde content

[0073] Furthermore, the free formaldehyde content of the resol resin will also be evaluated to verify the ability of the stabilizer to react with residual formaldehyde (formaldehyde scavenging function).

[0074] For this purpose, approximately 1 g of resol resin is placed in a 100 mL volumetric flask, and the mass m of the sample is accurately recorded. Distilled water is added up to the filling mark. The free formaldehyde content is determined using a LANGE DR6000 colorimeter included with the LCK 325 formaldehyde quantification kit, according to the manufacturer's instructions.

[0075] The measurement is performed using a 1 mL sample placed in a pretreatment flask. The result A obtained by the colorimeter is given in mg / L. The free formaldehyde content is calculated as follows: Free formaldehyde content (%) = (A × 0.1) / m × 100.

[0076] The free formaldehyde content is given as a percentage of the sample and expressed with an accuracy of ±0.01%. Any result less than 0.01% is denoted as <0.01%.

[0077] Ammonia emissions

[0078] Finally, the amount of ammonia released during the curing of various resol resins is evaluated by performing a contamination simulation in the laboratory. A resol resin solution equivalent to 1 g of solids is pre-diluted to a solids content of 30% and introduced into a 1 liter flat-bottom glass flask. The inlet of a dipper is connected to the flat-bottom flask, thereby scavenging the sample surface with an airflow rate of 1 L / min. The assembly is placed in a vented oven at 120°C for 15 minutes, and then the temperature is increased to 215°C and maintained for 1 hour. The outlet of the dipper is connected to three bubblers placed in sequence outside the oven, each containing 100 mL of 0.02 N sulfuric acid solution. The contents of the bubblers are analyzed by ion chromatography to quantify the amount of ammonia captured after each temperature step. Two measurements are performed for each test batch.

[0079] The measurement results for all substances tested as stabilizers, as well as reference urea and various formaldehyde scavengers listed in International Publication No. 2009 / 136105, are summarized in Table 1 below.

[0080] [Table 1]

[0081] Of all the organic compounds evaluated, only the urea derivative according to the present invention exhibits a stabilizing effect on resol resins that is at least equivalent to, or even higher than, that of urea: in fact, dilutability exceeding 1000% and crystalline stability over equivalent or greater periods are observed at urea derivative levels below the amount of urea used.

[0082] When these compounds are compared to urea, it is further confirmed that ammonia emissions are significantly reduced.

[0083] Furthermore, the precipitates formed in the presence of urea and the urea derivatives according to the present invention were analyzed by the method described by B. Mechin et al. in Eur. Polym. J. Vol. 22, no. 2, pp. 115-124 (1986) and Eur. Polym. J. Vol. 20, no. 4, pp. 333-341 (1984). The precipitates were subjected to HPLC analysis using a chromatograph equipped with a 280 nm UV detector or linked to a negative ion scanning mass spectrometer (m / z=319). The resulting chromatograms were compared with those of bis-4-diphenyltetramethylol (control) obtained by preparative chromatography. In this way, it was confirmed that the precipitates observed in the case of urea (comparative sample) and 4% by weight of 1-(2-hydroxyethyl)-2-imidazolidinone (sample according to the present invention) actually correspond to bis-4-diphenyltetramethylol. This was confirmed because the chromatograms obtained under ultraviolet light could be superimposed on those of the control, and the chromatograms obtained by mass spectrometry of the sample according to the present invention and the comparative sample (having specifically extracted ion 319) showed the same peaks as the control and exhibited similar retention times as the chromatogram obtained under ultraviolet light.

Claims

1. Stabilized resol resins, including the following: - water, - Amine-containing phenolic resin, and, - Urea derivatives of formula (I): R ３ R ４ -------R １ R ２ (I) Includes, Here: R １ However, hydrogen atoms, or linear or branched C atoms １ -C ６ It is an alkyl group, R ２ is a hydrogen atom, or a linear or branched C １ -C ６ alkyl group, or R ４ , and R ２ and R ４ together with the nitrogen atom to which they are attached form a 5- or 6-membered heterocyclic ring, R ３ However, hydrogen atoms, linear or branched C １ -C ６ Alkyl alkyl groups, or linear or branched C １ -C ６ It is a hydroxyl alkyl group, R ４ However, linear or branched C １ -C ６ Alkyl alkyl groups, or linear or branched C １ -C ６ It is a hydroxyalkyl group, or R ２ , and R ２ and R ４ Together with the nitrogen atom to which it is bonded, it forms a 5-membered or 6-membered heterocycle. The stabilized resol resin has a dry substance content of 40 to 70% by weight. Stabilized resol resin.

2. The following: - 75 to 99% by weight, preferably 80 to 97% by weight, and particularly 90 to 97% by weight of an amine-containing phenol resin, - 1 to 25% by weight, preferably 3 to 20% by weight, particularly 3 to 10% by weight, a urea derivative of formula (I), The stabilized resol resin according to claim 1, wherein the proportions of these are relative to the total dry weight of the stabilized resol resin.

3. The urea derivatives of formula (I) are as follows: R １ However, hydrogen atoms, linear or branched C １ -C ４ It is an alkyl group, preferably hydrogen, methyl, or ethyl. R ２ However, hydrogen atoms, linear or branched C １ -C ４ It is an alkyl group, or R ４ , and R ２ and R ４ Together with the nitrogen atom to which it is bonded, it forms a 5-membered or 6-membered heterocycle, which is preferably hydrogen, methyl, or ethyl, or R ４ , and R ２ and R ４ Together with the nitrogen atom to which it is bonded, it forms an imidazolidine ring. R ３ However, hydrogen atoms, linear or branched C １ -C ４ Alkyl alkyl groups, or linear or branched C １ -C ４ It is a hydroxyalkyl group, preferably hydrogen, methyl, ethyl, hydroxymethyl, or hydroxyethyl. R ４ However, linear or branched C １ -C ４ It is an alkyl group, or R ２ , and R ２ and R ４ Together with the nitrogen atom to which it is bonded, it forms a 5-membered or 6-membered heterocycle, which is preferably methyl or ethyl, or R ２ , and R ２ and R ４ Those that form an imidazolidine ring together with the nitrogen atom to which they are bonded, The stabilized resol resin according to claim 1 or 2.

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

5. A stabilized resol resin according to any one of claims 1 to 4, which does not contain urea.

6. The stabilized resol resin according to any one of claims 1 to 5, wherein the amine-containing phenol resin essentially consists of a phenol-formaldehyde condensate and a phenol-formaldehyde-amine condensate.

7. A binder composition comprising water, a stabilized resol resin according to any one of claims 1 to 6, and one or more additives selected from coupling agents, oils, hydrophobic agents, and curing reaction accelerators, wherein the binder composition contains 0 to 5% by weight of urea, preferably without urea, based on the dry weight of the binder composition.

8. The binder composition according to claim 7, comprising 75 to 98% by weight of water.

9. A method for stabilizing an amine resol resin, comprising adding to the resin a urea derivative defined in at least one of claims 1, 3, and 4 within 1 minute to 12 hours, preferably 1 minute to 2 hours, following its synthesis and cooling to below 30°C.

10. Use of a stabilized resol resin according to any one of claims 1 to 6 for the production of a binder composition.

11. A method for manufacturing a barrier article based on inorganic or organic fibers, the following: - Applying the binder composition according to claim 7 or 8 to inorganic fibers or organic fibers, preferably inorganic fibers, - Heating the fibers coated with the binder composition to evaporate the volatile phase of the binder composition and to thermally cure the non-volatile residue, or packaging the inorganic or organic fibers coated with the binder composition for storage and / or transport. Methods that include...

12. The method according to claim 11, wherein the inorganic fiber is selected from mineral wool fibers, particularly glass wool or rock wool.

13. A barrier article based on inorganic fibers or organic fibers, obtained by the method described in claim 11 or 12.

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