EA040645B1 - METHOD FOR MANUFACTURING PRODUCTS FROM MINERAL WOOL - Google Patents

Description

The field of technology to which the invention belongs

The present invention relates to a method for the manufacture of mineral wool products with binders based on phenol-formaldehyde resols. The resulting mineral wool products are primarily intended for use as heat and sound insulation of objects such as buildings, vehicles, air ducts and equipment.

Prerequisites for the creation of the invention

Mineral wool products are widely used for heat and sound insulation of various parts of buildings, vehicles or equipment, as well as for fire protection. Mineral wool products are basically randomly woven masses of mineral fibers of various lengths and are usually held together with a cured resin binder. Three types of mineral materials are most commonly used: glass, stone, or slag. Methods for making mineral wool products are well known in the art and typically include the steps of melting the mineral material to an appropriate temperature, converting the molten mixture into fine fibers, applying (generally spraying) an uncured liquid binder composition to the individual fibers while they still have some residual heat, collecting fibers and forming the primary fleece on a perforated conveyor, compacting the fleece and curing the binder at elevated temperatures. The cured mat is then cut to the desired size with cross and edge shears before it is packaged for shipping.

The most widely used binders are based on thermoset aqueous phenol-formaldehyde resols due to their good performance and attractive low cost. The most common phenol-formaldehyde resols used for this purpose are obtained by methylolation (hydroxymethylation) of phenol with formaldehyde and partial condensation in aqueous solution catalyzed by strong alkalis. A detailed description of the preparation and characterization of phenol-formaldehyde resols suitable for use in mineral wool binders can be found, for example, in 'Phenolic Resins: A Century of Progress', chapter 10, edited by L. Pilato and published by Springer-Verlag in 2010.

Phenol-formaldehyde resols for the manufacture of mineral wool are characterized by the fact that they are obtained with a stoichiometric excess of formaldehyde, which leads to the formation of free, unreacted formaldehyde mixed with the reaction product of the resole. In recent years, there has been growing concern about the toxicity of formaldehyde and formaldehyde-containing materials, which has led to the development of approaches to address this problem.

In this regard, urea has been found to be very useful, so much so that it is now almost always added to the resols used to make mineral wool. Urea plays a dual role: first, it acts as a formaldehyde scavenger, interacting with free formaldehyde in resole and thus reducing its concentration; and second, it acts as a resin filler by being incorporated into the cured thermoset binder without unacceptably degrading its properties, and thus increasing the usefulness of the binder solid at low cost. Commonly used urea loading levels are from 20 to 40% by weight, depending on the starting resole, relative to the sum of the dry weight content of the resole and the weight of urea. Higher urea loading levels without countermeasures have been reported to result in reduced mechanical properties of the binder, especially after aging, as well as high ammonia emissions and nuisance blue smoke during mineral wool production.

Urea can be added to phenol-formaldehyde resole immediately after the reaction between phenol and formaldehyde is quenched. The mixture of resole and urea is then allowed to react, typically at temperatures up to 60°C and for up to 24 hours. In the industry, this process is often referred to as premixing or prereaction, and the resulting phenol-formaldehyde-urea product is referred to as a premix or prereaction product. . The pre-reaction product is then stored and transported prior to use. There are known disadvantages associated with using the process with a urea pre-reaction product; the pre-reaction product is significantly less stable than phenol-formaldehyde resol (the higher the urea level, the less stable), resulting in much shorter shelf life. In addition, temperatures <10° C. must be avoided for the pre-reaction product.

To solve stability problems, alternatively, urea can be added to the phenol-formaldehyde resole by the mineral wool manufacturer at his production site shortly before applying the mixture to the mineral fibers. Thus, long-term storage or transport of the pre-reaction product is no longer required. In this case, urea is sometimes referred to in the industry as cold added to distinguish it from prereaction product formation (in the prereaction product process, urea is often added to the resole reaction product while it is still warm). However, the cold addition of urea also has its disadvantages. For example, the presence of unreacted urea, which has not had sufficient time to react, is associated with an increase in undesirable emissions of ammonia and amines during mineral wool manufacture. In addition, when urea is first added just prior to application to the fibers, high free formaldehyde resoles must be stored, transported and handled with regard to their respective toxicity concerns.

The combination of pre-reaction and cold addition of urea is described, for example, in US Pat. However, the disclosed free formaldehyde content of the original resols, expressed relative to wet weight rather than dry weight, indicates that the disclosed original resols require high levels of free formaldehyde.

While the use of urea has proven beneficial in reducing free formaldehyde problems in phenol-formaldehyde resole binders, it has not been completely satisfactory with respect to formaldehyde emissions from manufactured mineral wool products. This is due to the fact that the reaction products between urea and formaldehyde have not been confirmed to have sufficient thermal stability, and when cured at temperatures above 100° C., they form formaldehyde, which is released from finished mineral wool products.

The reduction of formaldehyde emissions from mineral wool products has been the subject of extensive research. Most approaches use formaldehyde scavengers other than urea to irreversibly scavenge excess formaldehyde, such as melamine, dicyandiamide, alkanolamines, glycine, and active methylene groups, among others. However, this approach has significant drawbacks. The most important of these are the additional costs of the absorbents used, as well as the need for additional processing steps and installations. In addition, scavengers can adversely affect the stability and processability of the resin.

The inventors of the present invention have observed that there is a need in the field for an improved method for the manufacture of mineral wool products with a binder based on phenol-formaldehyde resols, which avoids the storage, transportation and handling of materials having a high content of free formaldehyde, and which results in mineral wool products. with reduced formaldehyde emissions without the need for formaldehyde scavengers other than urea.

Description of the invention

In view of the foregoing, the inventors have developed an alternative method that provides a combination of a number of important advantages both in relation to the manufacture of mineral wool products and in relation to the products themselves, advantages that are surprising and unexpected in the prior art.

According to the invention, the method includes the first step of providing an aqueous phenol-formaldehyde resole containing free formaldehyde (step a)). In other words, the method involves providing an aqueous product of methylolation and condensation of the phenolic compound with formaldehyde under alkaline conditions, while the formaldehyde is in a molar stoichiometric excess relative to the phenolic compound, so that after the reaction, an excess of free, unreacted formaldehyde remains mixed with the reaction product.

Preferably aqueous phenol-formaldehyde resols with a low free formaldehyde content, i. e. with a free formaldehyde content of 10 wt.% or less relative to the content by dry weight of resole, can be used in the method according to the invention without compromising the stability of the final products. Thus, in preferred embodiments, the aqueous phenol-formaldehyde resole in this step a) has a free formaldehyde content of 10 wt.% or less, preferably 6 wt.% or less, and also preferably at least 1 wt.% in relation to the dry mass content resole measured according to the ISO 9397:1995 method (hydroxylamine hydrochloride method).

In the next step (step b)) the process involves obtaining a phenol-formaldehyde-urea pre-reaction product by contacting the phenol-formaldehyde resole with a first amount of urea (U1) and leaving the mixture of resole and urea for the reaction to proceed. When urea is contacted with a phenol-formaldehyde resole containing free formaldehyde, in a so-called pre-mixing step and among other reactions that occur, urea reacts with free formaldehyde by urea methylolation. As a result, the content of free formaldehyde in the resole decreases sharply with an increase in the amount of urea used. The phenol-formaldehyde-urea pre-reaction product is understood to mean the mixture of the reaction product which is formed when urea is contacted with resole and after the mixture is left to react for a sufficient time and at a sufficient temperature to cause a drastic reduction in the free formaldehyde content. It should be understood that the reactions may still continue in the resulting prereaction product after

- 2 040645 as the formaldehyde content reached a lower plateau, but at a much slower rate.

In preferred embodiments, the phenol formaldehyde resole and urea are left to react for at least 1 hour, preferably at a temperature in the range of 10-60° C., to form the phenol formaldehyde-urea pre-reaction product of the step

b).

The phenol-formaldehyde-urea pre-reaction product obtained according to the preferred embodiments is stable for at least several days and even for at least several weeks. This time, the pre-reaction product is allowed to be transported, for example, from the resole manufacturer to the mineral wool manufacturer, and stored before being used as a mineral wool binder. By stable is meant that the pre-reaction product does not undergo significant deterioration in its properties, which are necessary for use as part of the binder in the manufacture of mineral wool. Some of the properties of the pre-reaction product that persist for several days or weeks include sufficiently low viscosity, sufficient water dilution, no settling, and/or adequate B-stage gel time.

In a subsequent step (step c)) of the process according to the invention, the phenol-formaldehyde-urea pre-reaction product obtained in step b) is contacted with a second amount of urea (U2). It should be understood that this step is performed separately from step b), i. e. from obtaining the pre-reaction product mentioned in the previous paragraphs. In preferred embodiments, a second amount of urea (U2) is added to the pre-reaction product at least 24 hours after the formation of the pre-reaction product, preferably at least 72 hours. This subsequent step c) is preferably carried out shortly before applying the mixture to the surface of the mineral fibers in the manufacture of mineral wool products, preferably less than 48 hours and more preferably less than 24 hours.

The resulting mixture of the pre-reaction product of phenol-formaldehyde-urea and urea obtained in step c) is then applied to the surface of the mineral fibers in the next step d) in accordance with the process of the invention. The mixture is applied as part of an aqueous binder, optionally containing at least one additive selected from cure catalysts (e.g. ammonium sulfate), resin fillers other than urea (e.g. carbohydrates), anti-dust agents (e.g. mineral oil), adhesion promoters ( silanes) and water repellants (eg silicones). Preferably the binder contains optional additives at a concentration of 1-30 wt.% relative to the non-aqueous content of the binder. According to some embodiments, the addition of a resin other than the aqueous phenol-formaldehyde resol obtained in step a) is omitted.

In some embodiments, in step d) the mixture of the phenol-formaldehyde-urea prereaction product and urea obtained in step c) is applied to the surface of the fibers as part of the aqueous binder, with a non-aqueous content of 4-15% by weight relative to the weight of the aqueous binder, preferably in the range of 6-13 wt.%, even more preferably 8-10 wt.%.

Preferably, the mixture of the phenol-formaldehyde-urea-urea pre-reaction product and thus the binder is applied by spraying onto the surface of the freshly formed fibers exiting the fiber making machine.

The mixture of the phenol-formaldehyde-urea pre-reaction product and urea applied as part of the binder to the fibers is then cured in the next step (step e)) in the process according to the invention.

In preferred embodiments, the phenol-formaldehyde-urea/urea pre-reaction mixture is cured by passing the mineral fibers carrying it through an air circulation oven set at a temperature above 100°C, preferably at a temperature in the range of 140-180°C. The curing time is preferably 3-5 minutes.

The method according to the invention is further characterized by the following features:

(i) the total amount of urea (Ut) is from 30 to 35 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in c) is 20-35 wt. .% of total urea (Ut); or (ii) the total amount of urea (Ut) is about 40 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in c) is about 25 wt.% from the total amount of urea; or (iii) the total amount of urea (Ut) is from 42 to 50 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in c) is 15-52 wt.% of the total amount of urea (Ut); or (iv) the total amount of urea (Ut) is from 42 to 50 wt.% relative to the sum of the content

- 3 040645 dry weight of phenol-formaldehyde resole and total urea (Ut), and the second amount of urea (U2) used in c) is from 63 to 66 wt.% of the total urea; or (v) the total amount of urea (Ut) is about 45 wt.% relative to the sum of the dry weight content of the phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in c) is about 56 wt.% from the total amount of urea.

In the context of the present invention, it should be understood that the range from 30 to 35 wt.% also includes 29.6 wt.%, 29.7 wt.%, 29.8 wt.% and 29.9 wt.%. The total amount of urea used (Ut) is the result of the addition of the first amount of urea (U1) used to form the prereaction product in step b) and the second amount of urea (U2) used to form the mixture of prereaction product and urea in step c). The inventors have found that when Ut is below 10 wt.%, formaldehyde emissions increase significantly. On the other hand, Ut above 60 wt.% leads to a decrease in the mechanical properties of the binder and high emissions of ammonia.

In a specific embodiment, the total amount of urea (Ut) is 30-35 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and U2 is 22-33 wt.%, preferably 25-30 wt.% of total urea (Ut), or total urea (Ut) is 42-50 wt.%, preferably 45-48 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and U2 is 15-50 wt.%, preferably 20-48 wt.%, preferably 25-45 wt.%, preferably 30-43 wt.%, preferably 35-40 wt.% of the total amount of urea (Ut).

In a preferred embodiment, the total amount of urea (Ut) is from 30 to 35 wt.%, preferably 33 wt.% relative to the sum of the dry weight content of phenol formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in the step c), is 20-35 wt.% of the total amount of urea (Ut). In another preferred embodiment, the total amount of urea (Ut) is from 42 to 50 wt.%, preferably from 43 to 48 wt.%, relative to the sum of the dry weight content of phenol formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in step c) is 15-52 wt.% of the total amount of urea (Ut). In another preferred embodiment, the total amount of urea (Ut) is from 42 to 50 wt.%, preferably from 43 to 48 wt.%, relative to the sum of the dry weight content of phenol formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) , used in step c) is 63-66 wt.%, preferably about 65 wt.% of the total amount of urea (Ut). In another preferred embodiment, the total amount of urea (Ut) is about 40 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in step c) is about 25 wt. .% of total urea (Ut). In another preferred embodiment, the total amount of urea (Ut) is about 45 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in step c) is about 56 wt. .% of total urea (Ut).

According to some embodiments, the addition of resin other than the aqueous phenol-formaldehyde resole in step a) is omitted. In particular embodiments, the addition of sodium silicate resins, polyester resins, melamine resins, novolac resins, epoxy resins, polyamide resins, furan resins, phosphate resins, or combinations thereof is excluded.

In particular, the inventors unexpectedly found that when Ut is 30 to 35 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and total urea (Ut), and U2 is 20-35 wt.% of total urea, or when Ut is 42-50 wt.% and U2 is 15-52 wt.% or 63-66 wt.%, formaldehyde emissions in the finished product are significantly reduced.

The inventors surprisingly found that, assuming the same free formaldehyde content in the phenol-formaldehyde resole and the same total amount of urea used, the process according to the invention produces mineral wool products with formaldehyde emissions that are significantly reduced compared to those measured in the case of processes in which the same total amount of urea was used only during the preparation of the prereaction product, i.e. without fractional additions of urea. Without wishing to be bound by theory, it appears that fractional addition of urea to resol and contacting a second amount of urea (U2) with the pre-reaction product shortly before it is applied to the mineral fibers modifies the reaction pathways during curing in such a way that it results in that more formaldehyde binds irreversibly to the polymeric thermoset network formed during curing.

An additional advantage of the method according to the invention is that the first amount of urea (U1) can be added by the manufacturer of the phenol-formaldehyde resole itself after

- 4 040645 as the condensation reaction to obtain it will be completed, obtaining a pre-reaction product having a significantly lower content of free formaldehyde compared to the resole obtained by condensation. For example, the amount of urea used in this pre-mixing step may be selected to be sufficient to reduce the free formaldehyde content of the pre-reaction product to 0.9 wt% or less relative to the dry weight content of the pre-reaction product, preferably to 0 .2 wt.% or less when measured in accordance with ISO 11402:2004 (KCN method). The pre-reaction product with this substantially reduced free formaldehyde content is less problematic with respect to the potential toxicological and environmental problems associated with formaldehyde during storage, transport and handling of this material.

Thus, in preferred embodiments of the invention, the first amount of urea (U1) brought into contact with the phenol-formaldehyde resole in step b) is chosen so that it is sufficient to obtain a phenol-urea pre-reaction product with a free formaldehyde content of 0.9 wt. .% or less, preferably 0.2 wt.% or less, measured according to ISO 11402:2004 (KCN method) and refers to the dry weight content of the pre-reaction product.

The lower amount of urea used in the pre-mixing step in the process of the invention compared to the situation where the same total amount of urea (Ut) is used but not split (i.e. all urea is used in the pre-mixing step) results in higher stability of the pre-reaction product. The pre-reaction product obtained in the preferred embodiments is stable for at least one week, usually even for several weeks. The term stable means that the properties of the pre-reaction product, which are important for its applicability in the production of mineral wool, do not substantially deteriorate during this time. Such most important properties are, for example, good water dilution, low viscosity, no settling or adequate B-stage gel time.

The relatively lower amount of urea used in the pre-mixing step in the process of the invention also opens the way to using a phenol-formaldehyde resole with a relatively lower free formaldehyde content. It has been reported that the addition of a large molar stoichiometric excess of urea relative to the free formaldehyde in the resole to form the prereaction product may lead to undesirable precipitation of phenol formaldehyde tetradimer and reduce the stability of the prereaction product. Due to the relatively reduced amount of urea used in preparing the prereaction product in the process of the invention, resols with a lower free formaldehyde content, for example with a free formaldehyde content of 10 wt% or less relative to the dry weight content of the resole, can be used without compromising to an unacceptable degree of stability of the formed pre-reaction product.

The invention also relates to formaldehyde-reduced mineral wool products obtained by the method according to the embodiments described herein, and to the use of these mineral wool products for insulating buildings, vehicles, ducts, or appliances.

In addition, certain embodiments of the invention relate to a method for producing a low free formaldehyde content phenol formaldehyde-urea prereaction product, the method comprising providing a phenol formaldehyde resole having a free formaldehyde content of 10 wt.% or less, preferably 6 wt.% or less, also preferably at least 1 wt% based on the dry matter content of the resole, contacting the resole with a sufficient amount of urea to reduce the free formaldehyde content of the prereaction product to 0.9 wt% or less, preferably 0.2 wt% or less according to ISO 11402:2007 (KCN method) and relative to the dry matter content of the pre-reaction product, and leaving the mixture of resole and urea to react preferably for at least 1 hour, more preferably for at least 2 hours Also preferably the amount of urea in this embodiment in this process to obtain a pre-reaction product is at least 5 wt.%, more preferably at least 10 wt.% and preferably not more than 20 wt.% relative to the dry weight content of the pre-reaction product. In these embodiments, the phenol-formaldehyde resole is preferably substantially free of nitrided compounds (compounds containing at least one nitrogen atom), in particular substantially free of a compound selected from urea, ammonia, inorganic ammonium or organic salts, alkanolamines, alkylamines and/or melamine.

Definitions.

By essentially does not contain in the present description is meant that the concentration of the corresponding compound in the resole, the product of the pre-reaction or binder is low enough to be assessed as insignificant (negligible). However, in this

- 5 040645 context it should be understood that the compound in question may be present in trace amounts, for example, as a result of unintentional cross-contamination, preferably at a concentration of 0.1 wt.% relative to the dry weight of the resole, prereaction product or binder.

In the context of the present invention, the dry matter content is defined as the mass fraction of residue remaining after drying 3 g of an aqueous composition (resol, prereaction or binder) at 135° C. for 1 hour in a ventilated oven, as measured, for example, in accordance with ISO 3251:2008.

The term binder refers to an aqueous mixture of components that is applied to the fibers in the manufacture of mineral wool products and then cured to form a bond between the fibers at their intersection points with the cured binder. The binder is usually prepared in situ, which means that the binder is prepared at the mineral wool plant, usually continuously, shortly before being applied to the fibers.

By curing is meant that the material in question is subjected to a setting reaction (curing or cross-linking reaction), for example by heating above 100° C. in an oven (thermal curing).

Detailed description of embodiments of the invention

An aqueous phenol-formaldehyde resole suitable for the method of the present invention is a water-soluble curable resole containing free formaldehyde, resole, which is obtained by methylolation and condensation of a phenol compound with formaldehyde in the presence of an alkaline catalyst using methods known in the prior art. In resols, the phenol:formaldehyde molar ratio is <1. Phenol-formaldehyde resols are reactive mixtures with methylol functional groups that undergo a self-curing reaction under the action of heat or acids. Resols are thus partially reacted thermoset polymers, also known as resins, prepolymers or precondensates, which are stable at low temperature and alkaline pH and which can be further condensed to a thermoset polymer in a curing reaction by applying heat and/or at an acidic value. pH. The person skilled in the art knows how such resole is typically produced and knows how to modify the various reaction phases and reaction parameters to obtain the characteristics described in the preferred embodiments of the invention. Such parameters include, for example, the phenol:formaldehyde molar ratio, the type and amount of catalyst, and the time and temperature of the condensation reaction.

The molar ratio of phenol:formaldehyde to obtain resole in the process according to the invention is preferably in the range of 1:2 to 1:6. The stoichiometric excess of formaldehyde ensures the predominant formation of low molecular weight compounds as a result of methylation and condensation, a lower solution viscosity and a low content of free phenol in the resole. The molar excess of formaldehyde also causes free unreacted formaldehyde to be present in the aqueous resole after the reaction.

Although for the sake of clarity in this description a suitable resole is referred to as a phenol-formaldehyde resole, it should be understood that this does not imply that the resole can contain only unsubstituted phenol and formaldehyde as components. Other components may be present in the resole without departing from the scope of the invention. Such components can be, for example, substituted phenol derivatives such as alkylphenols, phenol esters or resorcinol and its derivatives, or formaldehyde-related compounds such as paraformaldehyde, or higher aldehydes such as butyraldehyde, acrolein or glyoxal. Other compounds containing hydroxyl or carboxyl groups can also react with phenol and formaldehyde, such as carbohydrates or alkanolamines, and even compounds having functional groups other than hydroxyl or carboxyl groups, such as hexamethylenetetramine, can be included in the reaction. However, it is preferable that the sum of the weights of unsubstituted phenol and formaldehyde in the resole is at least 80 wt.%, preferably at least 90 wt.% of the dry weight of the resole.

Mainly resols with a low content of free formaldehyde, i.e. with a free formaldehyde content of 10% by weight or less relative to the dry weight content of resole can be used in the method of the invention. In accordance with some embodiments of the invention, the content of free formaldehyde in the resole is preferably 10 wt.% or less, more preferably 6 wt.% or less, also preferably at least 1 wt.% relative to the dry weight content of the resole when measured in accordance with the method ISO 9397:1995 (hydroxylamine hydrochloride method). The main advantage of using resole with these levels of free formaldehyde in the process of the invention is that the mineral wool products produced using the method of these embodiments have satisfactory mechanical characteristics and, in addition, they have lower formaldehyde emissions. In particular, the sufficiently low content of free formaldehyde in the resole makes it possible to manufacture mineral wool products with formaldehyde emissions.

- 6 040645 below 10 µg/m ³ and more preferably below 8 µg/m ³ . Formaldehyde emissions from mineral wool products refer to emissions when the products are stored in an air exchange test chamber under controlled conditions for 28 days, and then the concentration of formaldehyde in the air in the chamber is measured according to ISO 16000-3:2011 standard method.

In accordance with the method of some embodiments, the preferred phenol-formaldehyde resole has a content by dry weight of 40-60 wt.%. The content of unreacted free phenol in the resole is preferably not more than 6 wt.%, more preferably not more than 2 wt.% relative to the dry weight content of the resole. The dilution of resole with water in demineralized water at 20° C. is suitably greater than 10 parts by weight. (this means that at least 10 g of water can be added to 1 g of resol until persistent turbidity appears), preferably more than 20 hours and more preferably more than 50 hours. The viscosity of the resol is preferably not more than 50 mPa-s at 20 ° C, more preferably not more than 30 mPa-s, when measuring an aqueous solution of resole with a content by dry weight of 45 wt.%. The pH of the resole solution is preferably above 8, more preferably above 8.5 and even more preferably above 8.9. The gelation time of the B-stage resole is preferably 2 to 15 minutes at 130°C. The methods used to determine these values are known to those skilled in the art and are briefly explained in some level of detail below.

In preferred embodiments, the phenol-formaldehyde resole, prior to being contacted with urea to form the urea-phenol-formaldehyde pre-reaction product, has a total nitrogen concentration of less than 1.0 wt%, preferably less than 0.6 wt%, relative to the dry weight content of the resole. Preferably, this resol is substantially free of nitrided compounds (compounds containing at least one nitrogen atom), in particular substantially free of a compound selected from urea, ammonia, inorganic or organic ammonium salts, alkanolamines, alkylamines and/ or melamine.

The phenol-formaldehyde resol, in accordance with some embodiments of the invention, is substantially free of formaldehyde scavengers selected from the group consisting of amines, tannins, sulfite and bisulfite salts, compounds with methylene active groups, glycine, resorcinol and its derivatives, alkanolamines and their mixtures.

Resols having the properties described in the preferred embodiments are available from resol companies such as Momentive Performance Materials or Prefere Resins.

The process according to the invention includes the step (step b)) of contacting the phenol-formaldehyde resole with a first amount of urea (U1) and allowing the mixture of resole and urea to react to obtain a phenol-formaldehyde-urea pre-reaction product. The contacting step can be carried out by adding urea (either in solid or liquid form), usually with effective agitation, to the aqueous resole composition. After contacting the urea and resole, they are vigorously stirred and left to react for at least 1 hour, preferably at least 2 hours, either in the same reactor used to make the resole or in a separate container. The temperature during this step b), including the contacting, mixing and reaction phases leading to the formation of the pre-reaction product, is in the range from 10 to 100° C., preferably from 15 to 80° C., preferably from 18 to 70° C, preferably 20 to 60°C, preferably 30 to 50°C, more preferably 35 to 45°C. In a preferred embodiment, the temperature in step b) does not exceed 70°C, more preferably the temperature in step b) is in the range of 2060°C. Higher temperatures in the range of 10-100°C lead to an acceleration of the condensation reaction, so the reaction must be stopped earlier in order to avoid the promotion of condensation beyond the desired point. In a preferred embodiment, the phenol-formaldehyde resole and the first amount of urea (U1) are allowed to react in step b) of the process of the invention for at least 1 hour at a temperature of 10-60° C. to obtain a pre-reaction product.

In preferred embodiments, the first amount of urea (U1) contacted with the phenol-formaldehyde resole in step b) is chosen to be sufficient to produce a urea-phenol-formaldehyde pre-reaction product with a free formaldehyde content of 0.9% by weight or less relative to the dry weight content of the pre-reaction product, preferably 0.2 wt.% or less, as measured in accordance with ISO 11402:2004 (method using KCN).

The first amount of urea (U1) is preferably 34-85 wt.%, for example 44 wt.%, preferably from 48-85 wt.%, preferably from 65 to 80 wt.%, for example 75. wt.% relative to the total amount of urea ( Ut).

Particularly good results in terms of pre-reaction product stability, low free formaldehyde content in the pre-reaction product, and low formaldehyde emissions have been achieved using resole with a free formaldehyde content of less than 6 wt. in contact with a first amount of urea (U1) which is at least 34 wt.%, more preferably at least 48 wt.%, more preferably at least 65 wt.% relative to the total amount of urea (Ut).

In the next step c), the phenol-formaldehyde-urea pre-reaction product obtained in step b) was contacted with a second amount of urea (U2) to obtain a mixture of the pre-reaction product and urea. The start point of this step c) is separated in time from the end of step b) preferably at least 24 hours and more preferably at least 72 hours. pre-reaction and urea will be applied to the mineral fibers in the manufacture of mineral wool products. In contrast, the preparation of the phenol-formaldehyde-urea pre-reaction product is usually carried out by the resole manufacturer, who delivers the finished pre-reaction product to the mineral wool manufacturer.

In step c) the phenol-formaldehyde-urea pre-reaction product and the second amount of urea (U2) can be brought into contact and well mixed in a container adapted for this purpose, or alternatively, and at present less preferred, contacting can be carried out. / mixing continuously in-line on the mineral wool production line, when the mixture is transported to the binder application site. The mixture of the pre-reaction product and the second amount of urea (U2) is preferably maintained at a temperature below 50°C, preferably below 40°C, more preferably below 30°C at all times and more preferably at 20-25°C until it is applied to the surface of the mineral fibers to avoid premature development of the condensation reaction.

The phenol-formaldehyde-urea pre-reaction product and the second amount of urea (U2) are brought into contact and mixed shortly before the resulting mixture is applied to the surface of the mineral fibers, preferably less than 48 hours and more preferably less than 24 hours.

The method according to the invention provides that the total amount of urea (Ut), i. the sum of the first (U1) and second (U2) amounts of urea used in steps b) and c) relative to the sum of the dry weight of the phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) are used in the following ranges:

(i) when the total amount of urea (Ut) is 30-35 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), the second amount of urea (U2) used in c) is 20-35 wt. .% of total urea (Ut); or (ii) when the total amount of urea (Ut) is about 40 wt.% relative to the sum of the dry weight content of phenol formaldehyde resole and the total amount of urea (Ut), the second amount of urea (U2) used in c) is about 25 wt. % of total urea; or (iii) when the total amount of urea (Ut) is 42-50 wt.% relative to the dry weight sum of the phenol-formaldehyde resole and the total amount of urea (Ut), the second amount of urea (U2) used in c) is 15-52 wt. .% of total urea (Ut); or (iv) when the total amount of urea (Ut) is 42-50 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), the second amount of urea (U2) used in c) is 63-66 wt.% of the total amount of urea; or (v) when the total amount of urea (Ut) is about 45 wt.% relative to the dry weight content of phenol formaldehyde resol and the total amount of urea (Ut), the second amount of urea (U2) used in c) is about 56 wt. % of total urea. The inventors have surprisingly found that by using this combination of features, formaldehyde emissions from articles made from mineral wool are significantly reduced compared to when the same total amount of urea is used in the pre-reaction product alone (no cold addition of urea).

For the production of mineral wool articles according to the process according to the invention, in the next step d) a mixture of the phenol-formaldehyde-urea prereaction product and the second amount of urea (U2) from step c) is applied to the surface of the mineral fibres. A mixture of the pre-reaction product and a second amount of urea (U2) is applied to the fibers as part of the binder. The binder optionally contains additives used either to assist in the production of mineral wool products or to improve the properties of mineral wool products. The binder is preferably an aqueous composition with a non-aqueous content in the range of 4-15% by weight based on the weight of the aqueous binder.

The optional additives contained in the binder, in addition to the phenol-formaldehyde-urea pre-reaction product and the second amount of urea (U2), are preferably at a concentration of more than 1 wt.% and less than 30 wt.% relative to the non-aqueous content of the binder, more preferably at a concentration of 5- 25 wt.%, more preferably at a concentration of 10-20 wt.%, even more preferably at a concentration of 15-18 wt.%. Optional additives include at least one additive selected from the following groups of substances: i) curing catalysts such as ammonium sulfate; ii) resin fillers other than urea, such as carbohydrates;

iii) anti-dust agents such as mineral oil; iv) adhesion promoters such as silanes; And

v) water repellants such as silicones, in particular reactive silicones. Particularly preferred is the inclusion of up to 10% by weight of molasses and/or glucose as resin filler.

In some embodiments, resins are excluded from the optional additives. In particular embodiments, the addition of sodium silicate resins, polyester resins, melamine resins, novolac resins, epoxy resins, polyamide resins, furan resins, phosphate resins, or combinations thereof is excluded.

In preferred embodiments, the mixture of the phenol-formaldehyde-urea pre-reaction product and the second amount of urea (U2) will be substantially diluted with fresh or process water and optionally mixed with binder additives. If additives are not used, the binder may contain only a mixture of the pre-reaction product and a second amount of a mixture of urea (U2), preferably diluted with water to the desired concentration.

The concentration of the various components in the binder preferably ranges from 40 to 90 wt.% phenol-formaldehyde resole, 30-50 wt.% total urea (the sum of the first (U1) and second (U2) amounts of urea) and 1-20 wt.% additives based on non-aqueous mass of the binder.

In preferred embodiments, the mixture of the phenol-formaldehyde-urea prereaction product and the second amount of urea (U2) is applied in spray form to the weakened individual fine mineral fibers produced in the hot molten mineral fiber plant. Spraying can be carried out using spray nozzles or similar devices oriented in such a direction that the spray mixture is in contact with the surface of the weakened fibers. The mixture contacts the surface of the mineral fibers while they are still warm. The impregnated fibers are collected on a perforated conveyor in a forming chamber where the primary uncured mat is formed. At this stage, a significant part of the water contained in the binder evaporates.

The primary mat is then compacted and transported via a series of conveyors to a heated drying oven. The binder is then cured at temperatures above 100°C, preferably at a temperature of 140-180°C, more preferably 150-170°C, even more preferably 155-165°C. The curing time is preferably 2 to 5 minutes. The cured mineral wool mat is then cut and shaped to final dimensions, optionally rolled up and packaged.

In some embodiments, a mixture of the phenol-formaldehyde-urea pre-reaction product and a second amount of urea (U2) is applied as part of the binder to the fibers in an amount to provide a solid binder content relative to the weight of mineral fibers in the final mineral wool product after curing, ranging from 1, 5 to 15 wt.%, preferably 3-12 wt.%, even more preferably 5-10 wt.%. The amount of cured binder relative to the weight of mineral fiber in a mineral wool product is measured as LOI (weight loss on ignition) in accordance with ISO 29771:2008. Thus, in a preferred embodiment, the mineral wool product obtained by the method of the invention has an LOI in the range of 1.5 to 15% by weight.

It has been found that when the phenol-formaldehyde resole has a free formaldehyde content below 6 wt.% relative to the content by dry weight of the resole, the second amount of urea (U2) is in the range of 20 to 35 wt.% relative to the total amount of urea (Ut); and the total amount of urea (Ut) is 30-35 wt.% relative to the sum of the dry weight of resole and the total mass amount of urea (Ut), or when the second amount of urea (U2) varies from 63 to 66 wt.% relative to the total amount of urea ( Ut); and the total amount of urea (Ut) is 42-50 wt.% relative to the sum of the dry weight of resole and the total mass amount of urea (Ut), and without the need for additional formaldehyde absorbers, mineral wool products made in accordance with this embodiment of the method according to of the invention surprisingly show formaldehyde emissions below 10 µg/m ³ and even below 8 µg/m ³ when measured according to ISO 16000-3:2011. Thus, in one aspect, the present invention relates to a mineral wool product, with formaldehyde emissions below 10 µg/m ³ obtained using the method according to the invention, preferably with formaldehyde emissions below 8 µg/m ³ as measured in in accordance with ISO 16000-3:2011. In a preferred embodiment, the mineral wool product obtained by the method of the invention further has an LOI value in the range of 1.5 to 15% by weight. The mineral wool product obtained by the method of the present invention exhibits non-acid properties in terms of pH, that is, when said mineral product is in contact with water, said water does not acquire an acidic pH value.

- 9 040645

Testing methods.

The free formaldehyde content of the resole is measured, for example, according to the international standard ISO 9397:1995 using the hydroxylamine hydrochloride method. This method is based on the following general principle: the formaldehyde present in the resole is converted to an oxime with the help of hydroxylamine hydrochloride. The hydrochloric acid formed during this reaction is then determined by potentiometric back titration using sodium hydroxide solution. The content of free formaldehyde in the resole relative to its dry content is then calculated from the amount of sodium hydroxide.

The free formaldehyde content of the phenol-formaldehyde-urea prereaction product is measured according to ISO 11402:2004 using the KCN method. Alternative methods for measuring free formaldehyde are HPLC or NMR.

The content of free or unreacted phenol in the resole is measured, for example, in accordance with the international standard ISO 8974:2002. This International Standard determines free phenol content by gas chromatography using either a weighed amount of an internal standard added to the part to be tested or using an internal standard stock solution. The internal standard used is 1-octanol. The content of free phenol in the resole is then calculated relative to its dry weight content.

The nitrogen content of the phenol-formaldehyde resole is measured, for example, by the Kjeldahl method.

The dilution of resole with water (or miscibility) is measured with demineralized water at 20°C in accordance with the method of the international standard ISO 8989:1995. Resole dilution is a measure of the mass of demineralized water relative to the mass of aqueous resole, resulting in a constant turbidity of the liquid resole. This method involves adding water to the resole until the haze persists for at least 30 seconds after mixing.

The viscosity of the resole is measured at 20° C. using a Brookfield viscometer, for example with spindle 1 and at 60 rpm. The viscosity indicated in the present invention is based on an aqueous resole having a dry weight content of 45% by weight.

The B-stage resole gel time is measured at 130° C. according to the international standard ISO 8987:2005.

The cured binder content of a mineral wool product (LOI) is measured in accordance with the international standard ISO 29771:2008.

Formaldehyde emissions from mineral wool products are measured on freshly made samples, for example according to ISO 16000-3:2011. The method includes placing fresh samples in an acclimatized glass chamber with a capacity of 212 liters, equipped with a fan and set to a temperature of 23±1°C, a relative humidity of 50±5%, an air flow of 0.2±0.1 m/s, and an air exchange rate of 0.5 h ^-1 ±5% within 28 days. Other settings are a load factor of 1 m ² sample surface per 1 m ³ test chamber volume, and a specific air exchange rate of 0.5 m ³ /m ² -h. The formaldehyde released is determined in µg/m ³ from chamber air samples taken into adsorbent cartridges coated with 2,4-dinitrophenylhydrazine (DNPH) at the time of measurement (in this case after 28 days), and the hydrazones formed are then analyzed using a high performance liquid chromatography (HPLC) with UV absorption detection.

Examples

Phenol-formaldehyde resole, characterized in that it has a pH of 9.6, a viscosity of 20 mPa-s, dilution in demineralized water >50, a B-stage gel time of 3 minutes, a dry weight content of 45 wt.%, supplied by a commercial supplier, was used for the production glass wool products. This resole is further characterized by a phenol content of less than 2 wt.%, a nitrogen content of <0.6 wt.% and a free formaldehyde content of 6 wt.%, all wt.% based on the content of resole by dry weight.

In the examples of the invention, two amounts of urea, U1 and U2, were added to the phenol-formaldehyde resole in two separate steps. The first amount of U1 was used to prepare the phenol-formaldehyde-urea pre-reaction product, and it was added to the same reactor where the resol was prepared after the condensation reaction was quenched. The mixture was allowed to react for several hours in the same reactor. A week later, a second amount of urea U2 was added to the prereaction product and mixed with shaking at a temperature of approximately 25° C. for 1 hour before being used to make glass wool products.

The binder mixture was prepared by mixing the resulting mixture of the prereaction product and the second amount of urea U2 with water, ammonium sulfate, mineral oil and aminopropyltrimethoxysilane. The binder was applied to the surface of the glass wool fibers in small droplets using spray rings as the fibers from the disc fiberizer, weakened by the blower heaters, fell onto the perforated conveyor belt. The glass fiber bearing the binder was collected in the form of an uncured mat, compacted and transported to a curing oven where the binder was heated to a temperature of 140-180°C for

Claims (18)

3-5 minutes for its curing. After curing, the resulting glass wool mat had a density 29.5 kg / m ³ and a thickness of 100 mm. The cured binder content, measured as LOI, was 6.5 wt.% relative to the weight of the fibers. In the comparative example, the same procedure was repeated, except that all of the urea was added unseparated, in one single step, to form the pre-reaction product, and that urea was not subsequently added to the pre-reaction product. The table shows the amounts of urea U1 and U2 in mass percent relative to the total amount of urea in the examples of the invention and comparative examples, as well as the results obtained after 28 days on the release of formaldehyde from manufactured glass wool products. Total urea content U1 First urea content (wt % Ut) U2 Second urea content (wt % Ut) Formaldehyde emissions (µg/m ³ ) Example PFU30+U15 1 45% 66% 33% 7 Example PFU25+U10 2 35% 71% 29% 7 Example PFU15+U30 3: 45% 33% 66% 6 Example PFU20+U10 4: thirty% 66% 33% 9 Example PFU20+U10 5: 40% 75% 25% 8 Example PFU20+U10 6: 45% 44% 56% 7 Comparative example (PFU30) thirty% 100% 0% 12 The phenol-formaldehyde-urea pre-reaction product of Examples 1 to 6 had a free formaldehyde content of <0.2% by weight based on the dry weight of the pre-reaction product. CLAIM 1. Method for the manufacture of mineral wool, including the following steps: a) providing an aqueous phenol-formaldehyde resole with free formaldehyde; b) obtaining a phenol-formaldehyde-urea pre-reaction product by contacting the resole with a first amount of urea (U1) and leaving the mixture for the reaction to proceed; c) contacting the pre-reaction product with a second amount of urea (U2); d) applying the resulting mixture of the pre-reaction product and a second amount of urea (U2) as part of the binder onto the surface of the mineral fibres; And e) curing the binder on the surface of the mineral fibers; while (i) the total amount of urea (Ut) is 30-35 wt.% relative to the sum of the content by dry weight of phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in c) is 20- 35 wt.% of the total amount of urea (Ut); or (i i) the total amount of urea (Ut) is 40 wt.% relative to the dry weight content of phenol formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in c) is 25 wt.% of total amount of urea; or (i ii) the total amount of urea (Ut) is from 42 to 50 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in c) is 15 -52 wt.% of the total amount of urea (Ut); or (i v) the total amount of urea (Ut) is 42-50% by weight relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in c) is 63-66 wt.% of the total amount of urea; or (v) the total amount of urea (Ut) is 45 wt.% relative to the sum of the dry weight content of phenol formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used in c) is 56 wt.% of total amount of urea. 2. The method according to claim 1, characterized in that the total amount of urea (Ut) is 30-35 wt.% relative to the sum of the content by dry weight of phenol-formaldehyde resole and the total amount of urea (Ut), and U2 is 22-33 wt.% , preferably 25-30 wt.% of the total amount of urea (Ut), or characterized in that the total amount of urea (Ut) is 42-50 wt.%, pre- - 11 040645 respectfully 45-48 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut), and U2 is 15-50 wt.%, preferably 20-48 wt.%, preferably 25-45 wt. %, preferably 30-43 wt.%, preferably 35-40 wt.% of the total amount of urea (Ut). 3. The method according to claim 1, characterized in that the total amount of urea (Ut) is 30-35 wt.% relative to the sum of the content by dry weight of phenol-formaldehyde resole and the total amount of urea (Ut), and the second amount of urea (U2) used c), is 20-35 wt.% of the total amount of urea (Ut), or characterized in that the total amount of urea (Ut) is 4250 wt.% relative to the sum of the dry weight content of phenol-formaldehyde resole and the total amount of urea (Ut) , and the second amount of urea (U2) used in c) is 63-66 wt.% of the total amount of urea. 4. The method according to any of the preceding paragraphs, provided that the addition of resin other than the aqueous phenol-formaldehyde resole of step a) is excluded. 5. Process according to any one of the preceding claims, characterized in that the phenol-formaldehyde resole in step a) has a free formaldehyde content of not more than 10 wt. % relative to the content by dry weight of the resole, preferably not more than 6 wt. %. 6. The method according to any one of the preceding claims, characterized in that the phenol-formaldehyde resole has a water dilution at 20°C of more than 10 parts by weight, a viscosity of not more than 50 mPa-s at 20°C and a dry weight content of 45 wt.%, pH above 8 and gelation time in the B-stage 2-15 min at 130°C. 7. Process according to any one of the preceding claims, characterized in that in step b) the phenol-formaldehyde resole and the first amount of urea (U1) are left to react for at least 1 hour, preferably at a temperature of 10-60°C to obtain a preliminary product reactions. 8. Process according to any one of the preceding claims, characterized in that in step c) a second amount of urea (U2) is added to the pre-reaction product at least 24 hours, preferably at least 72 hours after the formation of the pre-reaction product. 9. Process according to any one of the preceding claims, characterized in that the pre-reaction product and the second amount of urea (U2) are brought into contact in step c) less than 48 hours before this mixture is applied to the surface of the fibers in step d). 10. A process according to any one of the preceding claims, characterized in that in step d) a mixture of the pre-reaction product and a second amount of urea (U2) is applied to the mineral fibers as part of a binder containing additives in a concentration of 1-30% by weight relative to the non-aqueous content of the binder . 11. Process according to any one of the preceding claims, characterized in that the first amount of urea (U1) in step b) is selected to obtain a pre-reaction product with a free formaldehyde content of 0.9 wt.% or less, preferably 0.2 wt.% or less relative to the dry weight content of the pre-reaction product. 12. Process according to any one of the preceding claims, characterized in that the phenol-formaldehyde resole in step a) has a total nitrogen concentration of less than 1.0% by weight, preferably less than 0.6% by weight, relative to the content by dry weight of the resole. 13. The method according to any one of the preceding claims, characterized in that the phenol-formaldehyde resole in step b) does not contain formaldehyde scavengers selected from the group consisting of amines, tannins, sulfite and bisulfite salts, compounds with methylene active groups, glycine, resorcinol and its derivatives, alkanolamines and mixtures thereof. 14. The method according to any one of the preceding claims, wherein the binder in step d) further comprises at least one additive selected from curing catalysts, resin fillers other than urea, anti-dust agents, adhesion promoters, water repellants. 15. A mineral wool product obtained by a method according to any one of the preceding claims, characterized in that the formaldehyde emissions of said mineral wool product are less than 10 µg/m ³ measured according to ISO 16000-3:2011. 16. A mineral wool product with formaldehyde emissions of less than 8 µg/m ³ as measured in accordance with ISO 16000-3:2011. 17. A mineral wool product according to claim 15 or 16, characterized in that the mineral wool product additionally has a weight loss on ignition (LOI) value of 1.5-15% by weight. 18. The use of a mineral wool product according to any one of claims 15 to 17 for the insulation of buildings, vehicles, air ducts and/or equipment. ^8j) Eurasian Patent Organization, EAPO Russia, 109012, Moscow, Maly Cherkassky per., 2