WO2025106414A1

WO2025106414A1 - Resin composition with reduced formaldehyde emission

Info

Publication number: WO2025106414A1
Application number: PCT/US2024/055484
Authority: WO
Inventors: Gerd Froehlich; Christine CHOUEIRI; Vy Ha Thuy NGUYEN; Misganaw Berhanu ADDIS
Original assignee: Allnex USA Inc
Current assignee: Allnex USA Inc
Priority date: 2023-11-13
Filing date: 2024-11-12
Publication date: 2025-05-22
Anticipated expiration: 2026-05-13
Also published as: WO2025106414A9

Abstract

A resin composition comprising an alkylated amino resin which is the reaction product of an amino compound, formaldehyde and an alcohol, wherein the resin composition is obtained by subjecting the alkylated amino resin to a thermal treatment under reduced pressure, thereby reducing the total content of methylol groups in the alkylated amino resin.

Description

RESIN COMPOSITION WITH REDUCED FORMALDEHYDE EMISSION

Technical Field

[0001] The present invention relates to resin compositions, in particular alkylated amino resins having reduced formaldehyde emission characteristics.

Background

[0002] Alkylated amino resins have been used for years in particular in the rubber goods and the industrial coating industries. In rubber compositions, alkylated amino resins - such as for example derivatives of amino-l,3,5-triazines - have been used as part of methylene acceptor/donor systems in reinforcing resins or adhesion promotor resins especially in the tire manufacturing industry. In industrial coatings, alkylated amino resins have been used for decades as crosslinking agents which are meant to react with functional groups (usually hydrogen-containing reactive groups) of polymers usually referred to as binder resins.

[0003] Despite the beneficial properties provided by these alkylated amino resins, these have generally the disadvantage of releasing formaldehyde as a volatile by-product under certain conditions or during operational steps. Formaldehyde emission may occur from the presence of residual free formaldehyde in the alkylated amino resins, but also during the manufacturing and usage of these resins, in particular during curing or crosslinking reactions involving such resins. As the emission of formaldehyde is environmentally undesirable and may raise health concerns, it has long been a desire of industry to find acceptable alternative alkylated amino resins and crosslinking systems, which emit no formaldehyde or at least have reduced formaldehyde emission characteristics.

[0004] Partial solutions are described e.g. in US 7, 034,086 B2 (Lin et al.) which discloses melamine and guanamine-based crosslinking compositions, and in US 9,605,178 B2 (Gupta et al.) which discloses addition products of a cyclic urea and glyoxal and/or other multifunctional aldehydes that can be used as crosslinkers for coating compositions. Other partial solutions are disclosed in US 2022/0041843 Al (Landreau et al.) and in US 2012/283360 Al (Veyland et al.) which disclose a rubber composition based on at least a diene elastomer, a reinforcing filler, a crosslinking system, an epoxy resin, an amine-comprising curing agent, and optionally an imidazole. [0005] Without contesting the technical advantages associated with the solutions known in the art, there is still a need for alkylated amino resins having reduced formaldehyde emission characteristics.

Summary

[0006] According to one aspect, the present disclosure relates to a resin composition comprising an alkylated (etherified) amino resin which is the reaction product of an amino compound, formaldehyde and an alcohol, wherein the resin composition is obtained by subjecting the alkylated (etherified) amino resin to a thermal treatment under reduced pressure, thereby (irreversibly) reducing the total content of (unalkylated) methylol groups in the alkylated amino resin.

[0007] According to another aspect, the present disclosure is directed to a sulfur-crosslinkable rubber mixture comprising a rubber component and a resin composition as described above.

[0008] According to still another aspect, the present disclosure is directed to a curable composition comprising a resin composition as described above.

[0009] In still another aspect of the disclosure, it is provided a method for reducing the formaldehyde emission of an alkylated (etherified) amino resin, wherein the method comprises the steps of: a) providing an alkylated amino resin which is the reaction product of an amino compound, formaldehyde and an alcohol; and b) subjecting the alkylated amino resin to a thermal treatment under reduced pressure, thereby (irreversibly) reducing the total content of (unalkylated) methylol groups in the alkylated amino resin.

[0010] According to yet another aspect, the present disclosure relates to the use of a resin composition as detailed above for the manufacturing of (or in) a sulfur-crosslinkable rubber mixture as described above.

[0011] According to yet another aspect, the present disclosure relates to the use of a resin composition as detailed above for the manufacturing of (or in) a curable composition as described above. Detailed description

[0012] According to a first aspect, the present disclosure relates to a resin composition comprising an alkylated amino resin which is the reaction product of an amino compound, formaldehyde and an alcohol, wherein the resin composition is obtained by subjecting the alkylated amino resin to a thermal treatment under reduced pressure, thereby reducing the total content of methylol groups in the alkylated amino resin.

[0013] In the context of the present disclosure, it has been surprisingly found that a resin composition as described above is characterized by excellent reduced formaldehyde emission characteristics.

[0014] It has no less surprisingly been found that these excellent characteristics are provided even during the manufacturing and usage of the above-described resin composition, in particular during curing or crosslinking reactions involving such resin compositions. The resin composition of the present disclosure is as such particularly suitable for producing sulfur- crosslinkable rubber mixtures and curable compositions, in particular coating compositions.

[0015] These excellent characteristics and attributes are due in particular to the action of subjecting the alkylated amino resin (which is the reaction product of an amino compound, formaldehyde and an alcohol) to a thermal treatment under reduced pressure, thereby reducing the total content of methylol groups in the alkylated amino resin.

[0016] More specifically, it has been surprisingly found that the action of subjecting the alkylated amino resin to a thermal treatment under reduced pressure does not only allow reducing the content of residual free formaldehyde initially present in the alkylated amino resin, but also allows reducing the total content of methylol groups in the alkylated amino resin through what can be referred to as a (irreversible) demethylolation reaction. It has further been found that methylol groups present in the alkylated amino resin can act as latent precursors of formaldehyde which may result into unwanted formaldehyde emission. The formaldehyde resulting from the demethylolation reaction is therefore typically stripped from the alkylated amino resin during the thermal treatment under reduced pressure, thereby reducing the overall formaldehyde emission characteristics of the resulting resin composition. In the context of the present disclosure, achieving an irreversible demethylolation reaction is thus highly preferred in order to advantageously impact the overall formaldehyde emission reduction performance. In the context of the present disclosure, the reduction of the total content of methylol groups in the alkylated amino resin is believed to proceed according to an elimination reaction (of the methylol groups). Advantageously, the reduction of the total content of methylol groups in the alkylated amino resin occurs without increasing the total content of alkylated methylol groups in the alkylated amino resin when compared to the initial alkylated amino resin which was not yet subjected to a thermal treatment under reduced pressure.

[0017] The resin composition according to the disclosure, which is therefore obtained by subjecting the alkylated amino resin to a thermal treatment under reduced pressure, is characterized by unique features when compared to resin compositions known in the art and comprising an alkylated amino resin which is the reaction product of an amino compound, formaldehyde and an a alcohol. In particular, the resin composition as described herein is provided with a reduced total content of methylol groups in its inner structure, and a reduced content of residual free formaldehyde when compared to the initial resin composition comprising an alkylated amino resin which was not subjected to a thermal treatment under reduced pressure, and thus a resin composition as known in the art. The inventive resin composition is therefore provided with distinctive features which ultimately result into distinct properties, such as e.g. reduced formaldehyde emission characteristics.

[0018] This technical approach for reducing formaldehyde emission is seen as particularly counterintuitive considering that the latter actually involves actively releasing and stripping formaldehyde from latent precursors of formaldehyde which are (still) covalently bonded to the backbone of the alkylated amino resin. The technical solution as described herein is further counterintuitive considering that subjecting the alkylated amino resin to a thermal treatment under reduced pressure would have been expected to induce various detrimental effects to the alkylated amino resin, such as e.g. undue thermal stress, degradation reactions, unwanted side reactions, reduced reactivity (in particular towards crosslinking reactions) or unacceptable viscosity increase.

[0019] The resin composition of the present disclosure comprises an alkylated amino resin which is the reaction product of an amino compound, formaldehyde and an alcohol.

[0020] According to a typical aspect, the resin composition of the present disclosure comprises greater than 80 wt.%, greater than 85 wt.%, greater than 90 wt.%, greater than 95 wt.%, greater than 98 wt.%, or even greater than 99 wt.% of the alkylated amino resin, based on the total weight of the resin composition.

[0021] In one exemplary aspect, the resin composition of the present disclosure consists essentially of the alkylated amino resin. [0022] According to another exemplary aspect, the resin composition comprises from 95 to 99.9 wt.%, from 96 to 99.9 wt.%, from 97 to 99.9 wt.%, from 96 to 99.7 wt.%, from 98 to 99.9 wt.%, from 98 to 99.5 wt.%, from 98.2 to 99.5 wt.%, from 98.2 to 99.2 wt.%, or even from 98.2 to 99 wt.%, of the alkylated amino resin, based on the total weight of the resin composition.

[0023] Alkylated amino resins for use herein are not particularly limited, as long as they are the reaction product of an amino compound, formaldehyde and an alcohol. Suitable alkylated amino resins for use herein will be easily identified by those skilled in the art in the light of the present disclosure.

[0024] In the context of the present invention, the term alkylated amino resin is typically meant to designate a compound or a mixture of compounds resulting from the reaction of an amino compound with formaldehyde thereby forming methylol groups bound to the nitrogen atoms (also typically referred to as the methylolation step), and wherein (at least part of) the methylol groups are further alkylated with an alcohol thereby forming alkylated methylol groups (also referred to as an alkylation step).

[0025] Alkylated amino resins for use herein may be prepared according to methods and techniques well known to those skilled in the art. One exemplary method for preparing suitable alkylated amino resin is described e.g. in US 7, 034,086 B2 (Lin et al.).

[0026] In a typical aspect, the alkylated amino resin comprises alkylated methylol groups. Typically still, the initial alkylated amino resin for use herein, i.e. the alkylated amino resin before being subjected to a thermal treatment under reduced pressure, has a total content of methylol groups greater than 4.0 wt.%, greater than 5 wt.%, greater than 6 wt.%, greater than 8 wt.%, greater than 10 wt.%, or even greater than 12 wt.%, based on the total weight of the alkylated amino resin, when measured by HPLC techniques according to the test method described in the experimental section.

[0027] According to an advantageous aspect, the resin composition of the present disclosure has a total content of (unalkylated) methylol groups no greater than 4.0 wt.%, no greater than 3.5 wt.%, no greater than 3.0 wt.%, no greater than 2.5 wt.%, no greater than 2.0 wt.%, or even no greater than 1.5 wt.%, based on the total weight of the alkylated amino resin (or based on the total weight of the resin composition), when measured by HPLC techniques according to the test method described in the experimental section.

[0028] In the context of the present disclosure, the total content of (unalkylated) methylol groups present in the resin composition is meant to refer to the total weight content of all the (monomeric) compounds derived from the alkylated amino resin and containing (unalkylated) methylol groups.

[0029] In a typical aspect, the resin composition as described herein has a total content of (unalkylated) methylol groups greater than 0 wt.%, greater than 0.1 wt.%, greater than 0.2 wt.%, greater than 0.3 wt.%, greater than 0.4 wt.%, or even greater than 0.5 wt.%, based on the total weight of the alkylated amino resin (or based on the total weight of the resin composition), when measured by HPLC techniques according to the test method described in the experimental section. Alkylated amino resins for use herein typically comprise residual methylol groups which usually derive from an incomplete alkylation step of the methylol groups obtained after the methylolation step and/or from an undesired hydrolysis of some of the alkylated methylol groups initially present in the alkylated amino resin.

[0030] In a particular aspect, the resin composition as described herein has a total content of methylol groups in a range from 0.5 to 4.0 wt.%, from 0.5 to 3.5 wt.%, from 0.5 to 3.0 wt.%, from 1.0 to 3.0 wt.%, from 1.0 to 2.5 wt.%, or even from 1.0 to 2.0 wt.%, based on the total weight of the alkylated amino resin (or based on the total weight of the resin composition), when measured by HPLC techniques according to the test method described in the experimental section.

[0031] The total content of methylol groups in the resin composition may be measured according to techniques and analytical methods well known to those skilled in the art. In the context of the present disclosure, the total content of methylol groups in the resin composition is measured by high-performance liquid chromatography (HPLC) techniques after suitable analysis of the relevant chromatographic monomeric peaks and their respective areas.

[0032] According to an alternative method, the total content of methylol groups in the resin composition is measured by using quantitative ¹³C-Nuclear Magnetic Resonance (¹³C-NMR) techniques.

[0033] According to another advantageous aspect, the resin composition of the present disclosure has a total content of (unalkylated) methylol groups no greater than 10 mol%, no greater than 8 mol%, no greater than 7 mol%, no greater than 6 mol%, no greater than 5 mol%, no greater than 4 mol%, no greater than 3 mol%, no greater than 2 mol%, no greater than 1 mol%, or even no greater than no greater than 0.5 mol%, when measured by ¹³C-NMR techniques according to the test method described in the experimental section. [0034] According to the present disclosure, the resin composition as described herein is obtained by subjecting the alkylated amino resin to a thermal treatment under reduced pressure. Suitable thermal treatments under reduced pressure are not particularly limited and are commonly known in the art. Suitable thermal treatments under reduced pressure for use herein will be easily identified by those skilled in the art in the light of the present disclosure. One exemplary thermal treatment under reduced pressure is also commonly known in the art as thermal stripping under reduced pressure.

[0035] In another particular aspect, the alkylated amino resin is subjected to a thermal treatment at a temperature no greater than 180°C, no greater than 175°C, no greater than 170°C, no greater than 165°C, or even no greater than 160°C. In the context of the present disclosure, it has been found that subjecting the alkylated amino resin to a thermal treatment at a temperature greater than those described above may increasingly lead to unwanted molecular build-up or premature gelling of these resins.

[0036] According to an advantageous aspect, the alkylated amino resin for use herein is subjected to a thermal treatment at a temperature greater than 130°C, greater than 135°C, greater than 140°C, greater than 145°C, or even greater than 150°C.

[0037] According to another advantageous aspect, the alkylated amino resin for use herein is subjected to a thermal treatment at a temperature in a range from 130 to 180°C, from 130 to 170°C, from 140 to 170°C, from 140 to 165°C, from 145 to 165°C, or even from 150 to 160°C.

[0038] In an advantageous aspect, the alkylated amino resin is subj ected to a thermal treatment at a gauge pressure lower than 0 mmHg, lower than -200 mmHg, lower than -300 mmHg, lower than -400 mmHg, lower than -450 mmHg, lower than -500 mmHg, lower than -550 mmHg, lower than -600 mmHg, lower than -650 mmHg, lower than -700 mmHg, or even lower than - 750 mmHg.

[0039] In an advantageous aspect, the alkylated amino resin is subjected to athermal treatment at an absolute pressure lower than 760 mmHg, lower than 560 mmHg, lower than 460 mmHg, lower than 360 mmHg, lower than 310 mmHg, lower than 260 mmHg, lower than 210 mmHg, lower than 160 mmHg, lower than 110 mmHg, lower than 60 mmHg, or even lower than 10 mmHg.

[0040] In an advantageous aspect, the alkylated amino resin is subj ected to a thermal treatment at a pressure lower than 101.3 kPa, lower than 74.6 kPa, lower than 61.3 kPa, lower than 47.9 kPa, lower than 41.3 kPa, lower than 34.6 kPa, lower than 27.9 kPa, lower than 21.3 kPa, lower than 14.6 kPa, lower than 7.9 kPa, or even lower than 1.3 kPa.

[0041] In another advantageous aspect, the alkylated amino resin is subjected to a thermal treatment at a pressure lower than 101.3 kPa, lower than 75 kPa, lower than 60 kPa, lower than 45 kPa, lower than 40 kPa, lower than 30 kPa, lower than 25 kPa, lower than 20 kPa, lower than 15 kPa, lower than 10 kPa, lower than 5 kPa, or even lower than 2 kPa.

[0042] In another advantageous aspect, the alkylated amino resin is subjected to a thermal treatment at a gauge pressure in a range from -5 to -760 mmHg, from -50 to -750 mmHg, from -100 to -750 mmHg, from -200 to -750 mmHg, from -300 to -750 mmHg, from -350 to -750 mmHg, from -400 to -750 mmHg, or even from -500 to -750 mmHg.

[0043] In another advantageous aspect, the alkylated amino resin is subjected to a thermal treatment at an absolute pressure in a range from 755 to 0 mmHg, from 710 to 10 mmHg, from 660 to 10 mmHg, from 560 to 10 mmHg, from 460 to 10 mmHg, from 410 to 10 mmHg, from 360 to 10 mmHg, or even from 260 to 10 mmHg.

[0044] In another advantageous aspect, the alkylated amino resin is subjected to a thermal treatment at an absolute pressure in a range from 100.6 to 0 kPa, from 94.6 to 1.3 kPa, from 87.9 to 1.3 kPa, from 74.6 to 1.3 kPa, from 61.3 to 1.3 kPa, from 54.6 to 1.3 kPa, from 47.9 to 1.3 kPa, or even from 34.6 to 1.3 kPa.

[0045] In still another advantageous aspect, the alkylated amino resin is subj ected to a thermal treatment at an absolute pressure in a range from 100 to 0 kPa, from 95 to 1.5 kPa, from 90 to 1.5 kPa, from 75 to 1.5 kPa, from 60 to 1.5 kPa, from 55 to 1.5 kPa, from 50 to 1.5 kPa, or even from 35 to 1.5 kPa.

[0046] According to a beneficial aspect, the alkylated amino resin is further subjected to a realkylation treatment of the methylol groups. The re-alkylation treatment of the methylol groups present in the alkylated amino resin may be performed before the thermal treatment under reduced pressure and/or after such thermal treatment under reduced pressure. The re-alkylation treatment as described herein contributes to further reduce the content of unalkylated methylol groups in the alkylated amino resin, and therefore advantageously impact the overall formaldehyde emission reduction characteristics of the resulting resin composition. When the re-alkylation treatment is performed after the thermal treatment under reduced pressure, it is aimed at re-alkylating those methylol groups of the alkylated amino resin which remained unaffected by the demethyl olati on reaction. [0047] Amino compounds for use in the preparation of the alkylated amino resins for use herein are not particularly limited, as long as they are reactive with formaldehyde to form methylol groups bound to the nitrogen atoms (i.e. N-m ethyl ol groups) and further reactive with an alcohol. More specifically, the amino compounds for use herein are typically capable of reacting with formaldehyde thereby forming a reaction product comprising methylol groups bound to the nitrogen atoms, and wherein the reaction product is further capable of reacting with an alcohol through an alkylation (or etherification) reaction thereby forming alkylated (or etherified) methylol groups. Suitable amino compounds for use herein will be easily identified by those skilled in the art in the light of the present disclosure.

[0048] According to an exemplary aspect, amino compounds for use herein are selected from the group consisting of amino-l,3,5-triazine derivatives, guanamine derivatives, urea derivatives, glycoluril, and any combinations or mixtures thereof.

[0049] Guanamine derivatives for use herein include, but are not limited to benzoguanamine, acetoguanamine, and mixtures thereof. Urea derivatives for use herein include, but are not limited to, urea, ethyleneurea, and any mixtures thereof.

[0050] According to an advantageous aspect, the amino compound is selected from the group consisting of amino-l,3,5-triazine derivatives; in particular l,3,5-triazine-2-amine, 1,3,5- triazine-2,4-diamine, and l,3,5-triazine-2,4,6-triamine.

[0051] According to an advantageous aspect, the amino compound is selected to be 1,3,5- triazine-2,4,6-triamine (also referred to as melamine).

[0052] Alcohols for use in the preparation of the alkylated amino resins for use herein are not particularly limited. Suitable alcohols for use herein will be easily identified by those skilled in the art in the light of the present disclosure.

[0053] In an exemplary aspect, the alcohol for use herein is selected from the group of monohydric alcohols, in particular from the group consisting of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, cyclohexanol, phenol, benzyl alcohol, and mixtures thereof.

[0054] In a typical aspect, the alcohol for use herein is selected from the group consisting of monohydric alcohols having from 1 to 6, or even from 1 to 4 carbon atoms.

[0055] Advantageously, the alcohol is selected from the group consisting of methanol, ethanol, propanol, butanol, and any mixtures thereof. More advantageously, the alcohol for use herein is selected from the group consisting of methanol, n-butanol, isobutanol, and any mixtures thereof.

[0056] In an advantageous aspect of the resin composition of the present disclosure, the amino resin is selected from the group consisting of melamine-formaldehyde resins, benzoguanamine- formaldehyde resins, urea-formaldehyde resins, melamine-urea-formaldehyde resins, glycoluril-formaldehyde resins, and any mixtures thereof.

[0057] In a more advantageous aspect, the amino resin for use herein is selected from the group consisting of melamine-formaldehyde resins, benzoguanamine-formaldehyde resins, and any mixtures thereof.

[0058] In a particularly advantageous aspect, the amino resin for use herein is selected to be a melamine-formaldehyde resin.

[0059] Advantageously, the alkylated amino resin for use herein comprises alkoxymethyl derivatives of melamine, alkoxymethyl derivatives of benzoguanamine, and any mixtures thereof.

[0060] Advantageously, the alkylated amino resin for use herein comprises alkoxymethyl derivatives of melamine, more in particular methoxymethyl derivatives of melamine.

[0061] Advantageously still, the alkylated amino resin for use herein comprises polymethoxymethyl melamine, in particular hexamethoxymethyl melamine, pentamethoxymethyl melamine, tetramethoxymethyl melamine, and any mixtures thereof.

[0062] According to an advantageous aspect, the resin composition of the present disclosure further comprises a formaldehyde scavenger.

[0063] In the context of the present invention, the term formaldehyde scavenger is typically meant to designate a compound capable of (reversibly or irreversibly) chemically reacting with formaldehyde through covalent bond formation thereby forming a formaldehyde adduct. Accordingly, compounds capable of displacing formaldehyde through (gas) entrainment (like e.g. aqueous or organic solvents such as water or alcohols) do not qualify as formaldehyde scavenger according to the present disclosure.

[0064] In the context of the present disclosure, it has been surprisingly found that the inclusion of a formaldehyde scavenger into the resin composition does not only allow further reducing the content of residual free formaldehyde initially present in the alkylated amino resin, but also allows durably maintaining the initial reduction of formaldehyde emission induced by the action of subjecting the alkylated amino resin to a thermal treatment under reduced pressure. Without being bound by theory, it is believed that the formaldehyde scavenger gradually and continuously assists in trapping any formaldehyde compound that might be gradually emitted from resin composition upon time. As such, the use of a formaldehyde scavenger is seen as a complementary means for further reducing formaldehyde emission and maintaining the excellent low formaldehyde emission characteristics of the resin composition of the present disclosure. In the context of the present disclosure, it has no less surprisingly been found that the use of a formaldehyde scavenger allows maintaining the excellent low formaldehyde emission characteristics of the resin composition of the present disclosure for a prolonged period of time, in particular for a period up to 6 months, and therefore advantageously impacts the long-term stability of the excellent formaldehyde emission characteristics of the resin composition of the present disclosure.

[0065] Formaldehyde scavengers for use herein are not particularly limited. Suitable formaldehyde scavengers for use herein will be easily identified by those skilled in the art in the light of the present disclosure.

[0066] In an exemplary aspect, the formaldehyde scavenger for use herein is selected from the group consisting of amino alcohols, urea, ethylene urea, ammonia, melamine, dicyandiamide, sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium sulfamate, ammonium bisulfite, ammonium sulfite, ammonium bicarbonate, ammonium carbonate, ammonium sulfamate, polyacrylamide, acrylamide, methacrylamide, biuret, triuret, biurea, polyurea, acid salts of aniline, aromatic amines, aliphatic amines, diethylene triamine, triethylene tetramine, tetraethylene pentamine, other polyamines and their salts, polyamidoamines, amino acids, aromatic amino acids, p-amino benzoic acid, polyethylneamines, methane sulfonamide, succinimide, actoacetamide, ethyl acetoacetate, carbodiimides, pyrogallol, and any combinations or mixtures thereof.

[0067] In an advantageous aspect, the formaldehyde scavenger is selected from the group consisting of amino alcohols, urea, ethylene urea, ammonia, and any combinations or mixtures thereof. In a more advantageous aspect, the formaldehyde scavenger is selected from the group consisting of amino alcohols, in particular beta-hydroxyamino compounds.

[0068] In a preferred aspect, the formaldehyde scavenger is selected from the group of beta- hydroxyamino compounds, in particular those selected from the group consisting of monoethanolamine (MEA), diethanolamine, 2-amino-l -propanol, 2-amino-l -butanol, 2- amino-2-methyl-l -propanol (AMP), 2-amino-2-methyl-l,5-propanediol, 2-amino-2-ethyl-l,3- propanediol (AEPD), 2-amino-2-(hydroxymethyl)-l,3-propanediol (AHMPD or trizma), and any mixtures thereof.

[0069] In the context of the present disclosure, it has been found that the scavenging reaction of free formaldehyde with beta-hydroxyamino compounds advantageously leads to forming thermally stable oxazolidine ring structures, and more advantageously bis-oxazolidine ring structures, which advantageously impacts the efficiency and durability of the overall formaldehyde emission reduction performance when compared to conventional amino-based formaldehyde scavengers.

[0070] According to a typical aspect, the resin composition comprises from 0.1 to 5 wt.%, from 0.1 to 4 wt.%, from 0.1 to 3 wt.%, from 0.3 to 3 wt.%, from 0.3 to 2 wt.%, from 0.5 to 2 wt.%, from 0.5 to 1.8 wt.%, from 0.8 to 1.8 wt.%, or even from 1 to 1.8 wt.%, of the formaldehyde scavenger, based on the total weight of the resin composition.

[0071] According to a particular aspect, the resin composition of the present disclosure may be adsorbed onto a solid carrier material. This particular form of execution could be particularly beneficial in those applications where a solid state material is more suitable. This is particularly the case in those applications where a solid state resin material would facilitate overall processing, handling and operational steps.

[0072] Solid carrier materials for use herein are not particularly limited. Any carrier material commonly known in the art may be used in the context of the present disclosure. Suitable solid carrier materials for use herein will be easily identified by those skilled in the art in the light of the present disclosure.

[0073] In an advantageous aspect, the solid carrier material for use herein comprises silicates, silica or salts thereof, in particular precipitated silica. Suitable solid carriers for use herein are commercially available from e.g. Evonik Industries under the tradename Sipernat®.

[0074] According to an advantageous aspect, the solid carrier material has a pH greater than 5, greater than 6, greater than 7, greater than 8, greater than 9, or even greater than 10.

[0075] According to another advantageous aspect, the solid carrier material for use herein has a pH in a range from 5.5 to 12, from 6 to 11, from 7 to 11, from 8 to 11, from 9 to 11, or even from 9.5 to 10.5. [0076] In the context of the present disclosure, it has been indeed surprisingly found that the use of low acidic and basic solid carrier materials, in particular basic solid carrier materials, advantageously impacts the efficiency and durability of the overall formaldehyde emission reduction performance when compared to conventional solid carrier materials, such as in particular acidic solid carrier materials. The use of in particular basic solid carrier materials has been found to help durably maintaining the initial reduction of formaldehyde emission induced by the action of subjecting the alkylated amino resin to a thermal treatment under reduced pressure. Without being bound by theory, it is believed that a basic solid carrier material helps inhibiting the partial moisture-induced hydrolysis of the alkylated methylol groups initially present in the alkylated amino resin, and which may potentially occur when using a more acidic solid carrier material. As such, the use of a basic solid carrier material is seen as a complementary means for further reducing formaldehyde emission and maintaining the excellent low formaldehyde emission characteristics of the resin composition of the present disclosure by efficiently preventing or at least substantially reducing the formation of new methylol groups . In the context of the present disclosure, it has no less surprisingly been found that the use of a basic solid carrier material allows maintaining the excellent low formaldehyde emission characteristics of the resin composition of the present disclosure for a prolonged period of time, in particular for a period up to 6 months, and therefore advantageously impacts the long-term stability of the excellent formaldehyde emission characteristics of the resin composition of the present disclosure. Suitable basic solid carriers for use herein are commercially available from e.g. Evonik Industries and Celite Corporation.

[0077] According to an advantageous aspect, the resin composition of the present disclosure has a formaldehyde emission value no greater than 15000 ppm, no greater than 10000 ppm, no greater than 8000 ppm, no greater than 7000 ppm, no greater than 6000 ppm, no greater than 5000 ppm, no greater than 4000 ppm, no greater than 3000 ppm, no greater than 2000 ppm, no greater than 1000 ppm, no greater than 900 ppm, no greater than 800 ppm, no greater than 700 ppm, no greater than 600 ppm, no greater than 500 ppm, no greater than 400 ppm, no greater than 350 ppm, no greater than 300 ppm, no greater than 250 ppm, or even no greater than 200 ppm, when measured according to the test method described in the experimental section.

[0078] According to another advantageous aspect, the resin composition as described herein has a formaldehyde emission value no greater than 15000 ppm, no greater than 10000 ppm, no greater than 8000 ppm, no greater than 7000 ppm, no greater than 6000 ppm, no greater than 5000 ppm, no greater than 4000 ppm, no greater than 3000 ppm, no greater than 2000 ppm, no greater than 1000 ppm, no greater than 900 ppm, no greater than 800 ppm, no greater than 700 ppm, no greater than 600 ppm, no greater than 500 ppm, or even no greater than 400 ppm, when measured after six month storage according to the test method described in the experimental section.

[0079] The resin composition of the present disclosure is as such particularly suitable for producing sulfur-crosslinkable rubber mixtures.

[0080] According to another aspect, the present disclosure is therefore directed to a sulfur- crosslinkable rubber mixture comprising a rubber component and a resin composition as described above.

[0081] Rubber components for use herein are not particularly limited. Any rubber component commonly known in the art of sulfur-crosslinkable rubber compositions may be used in the context of the present disclosure. Suitable rubber components for use herein will be easily identified by those skilled in the art in the light of the present disclosure. Exemplary rubber components for use herein are described e.g. in US 2022/0041843 Al (Landreau et al.) and in US 2012/283360 Al (Veyland et al.).

[0082] In a particular aspect, the rubber component for use herein is a diene elastomer, in particular a diene elastomer selected from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers, and any mixtures thereof.

[0083] In an advantageous aspect, the sulfur-crosslinkable rubber mixture according to the present disclosure comprises a methylene acceptor-methylene donor system, wherein the methylene donor is a resin composition as described hereinbefore.

[0084] Methylene acceptor-methylene donor systems for use herein are not particularly limited, as along as the methylene donor is chosen to be a resin composition as described above. Suitable methylene acceptors for use herein will be easily identified by those skilled in the art in the light of the present disclosure. Exemplary methylene acceptors are described e.g. in US 2012/0095152 Al (Schafer et al.) and in EP 3 649 191 Al (Rajan et al.).

[0085] According to an advantageous aspect, the methylene acceptor for use herein is selected from the group consisting of novolac resins, in particular phenol novolac resins. [0086] According to a more advantageous aspect, the methylene acceptor for use in the methylene acceptor-methylene donor system is selected from the group consisting of phenolformaldehyde novolac resins.

[0087] All the particular and advantageous aspects described hereinbefore with respect to the resin composition - in particular the alkylated amino resin, the action of subjecting the alkylated amino resin to a thermal treatment under reduced pressure, the optional formaldehyde scavenger and the optional solid carrier material - are fully applicable to the sulfur-crosslinkable rubber mixture according to the present disclosure.

[0088] When used for producing sulfur-crosslinkable rubber mixtures, the resin composition of the present disclosure is advantageously adsorbed onto a solid carrier material as described hereinbefore. This particular form of execution is particularly beneficial as it facilitates the overall processing, handling and operational steps associated with the sulfur-crosslinkable rubber mixture.

[0089] In an alternative execution though, the resin composition may also be used in a liquid form for producing sulfur-crosslinkable rubber mixtures.

[0090] The sulfur-crosslinkable rubber mixture as described herein may further comprise additional components which are customary in the art. Exemplary components include, but are not limited to, reinforcing agents, vulcanizing agents, curing agents, fillers, and any combinations or mixtures thereof. As will be easily apparent to those skilled in the art, suitable additional components will depend on the targeted applications and desired performance attributes.

[0091] According to another aspect, the present disclosure is directed to a finished or semifinished rubber article comprising a sulfur-crosslinked rubber mixture resulting from the sulfur- crosslinking of a sulfur-crosslinkable rubber mixture as described hereinbefore.

[0092] As will be easily apparent to those skilled in the art, suitable finished or semi-finished rubber articles for use herein may take various shapes, forms, and sizes depending on the targeted applications and desired performance attributes.

[0093] According to an advantageous aspect, the rubber article of the present disclosure is selected from the group consisting of pneumatic vehicle tires, tubes, drive belts, seals, conveyor belts, and any combinations thereof. [0094] According to a particularly advantageous aspect of the disclosure, the rubber article as described herein is a pneumatic vehicle tire. In the context of the present disclosure, it has been indeed surprisingly found that the resin composition as described herein is particularly suitable for reducing formaldehyde emissions in industrial tire manufacturing processes, especially during accelerated handling and compounding processing steps, therefore improving workers safety. Surprisingly still, these reduced formaldehyde emission characteristics are achieved without sacrificing the overall efficiency of the tire production and without detrimentally affecting the desired performance attributes of the resulting pneumatic vehicle tire.

[0095] According to still another aspect, the present disclosure relates to an adhesionpromoting system for a rubber article comprising a resin composition as described hereinbefore.

[0096] In a particular aspect, the adhesion-promoting system of the present disclosure comprises a methylene acceptor-methylene donor system as described hereinbefore, and wherein the methylene donor is advantageously a resin composition as described hereinbefore.

[0097] In an advantageous aspect, the adhesion-promoting system of the present disclosure is used for promoting adhesion between a rubber component and reinforcing agents based on steel cord or textile fiber cord.

[0098] In another advantageous aspect, the adhesion-promoting system as described herein is used for a rubber article selected from the group consisting of pneumatic vehicle tires, tubes, drive belts, seals, conveyor belts, and any combinations thereof.

[0099] According to yet another aspect, the present disclosure is related to a reinforcing system for a rubber article comprising a resin composition as described hereinbefore.

[0100] In a particular aspect, the reinforcing system of the present disclosure comprises a methylene acceptor-methylene donor system as described hereinbefore, and wherein the methylene donor is advantageously a resin composition as described hereinbefore.

[0101] In an advantageous aspect, the reinforcing system as described herein is used for a rubber article selected from the group consisting of pneumatic vehicle tires, tubes, drive belts, seals, conveyor belts, and any combinations thereof.

[0102] Exemplary adhesion-promoting systems and reinforcing systems for rubber articles are described e.g. in US 2012/0095152 Al (Schafer et al.) and in EP 3 649 191 Al (Rajan et al.). [0103] According to yet another aspect, the present disclosure is directed to a crosslinking system comprising a resin composition as described hereinbefore.

[0104] All the particular and advantageous aspects described hereinbefore with respect to the resin composition - in particular the alkylated amino resin, the action of subjecting the alkylated amino resin to a thermal treatment under reduced pressure, the optional formaldehyde scavenger and the optional solid carrier material - are fully applicable to the rubber article, the adhesion-promoting system, the reinforcing system and the crosslinking system according to the present disclosure.

[0105] The resin composition of the present disclosure is also particularly suitable for producing curable compositions, in particular curable coating compositions. In the context of the present disclosure, it has been indeed surprisingly found that the resin composition as described herein is particularly suitable for reducing formaldehyde emissions in curable (coating) compositions, while maintaining the desired performance attributes and properties of the curable composition - in particular its curing performance and characteristics - and/or of the resulting cured (coating) composition.

[0106] According to still another aspect, the present disclosure is therefore directed to a curable composition comprising a resin composition or a crosslinking system as described hereinbefore.

[0107] According to a particular aspect, the curable composition of the disclosure further comprises a polymeric binder having active hydrogen groups (or reactive groups).

[0108] Polymeric binders for use herein are not particularly limited. Any polymeric binder commonly known in the art of curable (coating) compositions may be used in the context of the present disclosure. Suitable polymeric binders for use herein will be easily identified by those skilled in the art in the light of the present disclosure. Exemplary polymeric binders for use herein are described e.g. in US 7,304,086 B2 (Lin et al.) and in US 9,605,178 B2 (Gupta et al.).

[0109] In an advantageous aspect of the curable composition, the polymeric binder for use herein comprises reactive functionalities selected from the group consisting of hydroxy, carboxy, amino, amido, carbamato, mercapto, or a blocked functionality which is convertible to any of the preceding reactive functionalities.

[0110] In another advantageous aspect, the polymeric binder for use herein is selected from the group of polyfunctional hydroxy group containing materials, such as polyols, hydroxyfunctional acrylic resins having pendant or terminal hydroxy functionalities, hydroxyfunctional polyester resins having pendant or terminal hydroxy functionalities, hydroxyfunctional polyurethane prepolymers, products derived from the condensation of epoxy compounds with an amine, products derived from the condensation of epoxy compounds with an anhydride or a bisphenol, and any mixtures thereof.

[0111] The curable composition as described herein may further comprise additional ingredients which are customary in the art. Exemplary ingredients include, but are not limited to, cure catalysts, fillers, light stabilizers, pigments, flow control agents, plasticizers, mold release agents, corrosion inhibitors, rheology modifiers, solvents, and any mixtures thereof. As will be easily apparent to those skilled in the art, suitable additional ingredients will depend on the targeted applications and desired performance attributes.

[0112] In a particularly advantageous aspect of the disclosure, the curable composition as described herein is a coating composition, in particular an amino resin coating composition.

[0113] All the particular and advantageous aspects described hereinbefore with respect to the resin composition - in particular the alkylated amino resin, the action of subjecting the alkylated amino resin to a thermal treatment under reduced pressure, the optional formaldehyde scavenger and the optional solid carrier material - are fully applicable to the curable composition according to the present disclosure.

[0114] In another aspect of the disclosure, it is provided a method for reducing the formaldehyde emission of an alkylated amino resin, wherein the method comprises the steps of: a) providing an alkylated amino resin which is the reaction product of an amino compound, formaldehyde and an alcohol; and b) subjecting the alkylated amino resin to a thermal treatment under reduced pressure, thereby reducing the total content of methylol groups in the alkylated amino resin.

[0115] In still another aspect of the disclosure, it is provided a method of manufacturing an alkylated amino resin with reduced formaldehyde emission, wherein the method comprises the steps of: a) allowing an amino compound, formaldehyde and an alcohol to react, thereby forming an alkylated amino resin; and b) subjecting the alkylated amino resin to a thermal treatment under reduced pressure, thereby reducing the total content of methylol groups in the alkylated amino resin.

[0116] All the particular and advantageous aspects described hereinbefore with respect to the resin composition - in particular the alkylated amino resin, the action of subjecting the alkylated amino resin to a thermal treatment under reduced pressure, the optional formaldehyde scavenger and the optional solid carrier material - are fully applicable to the method for reducing the formaldehyde emission of an alkylated amino resin and to the method of manufacturing an alkylated amino resin with reduced formaldehyde emission according to the present disclosure.

[0117] According to an advantageous aspect of the disclosure, the methods as described hereinbefore further comprise the step of adding a formaldehyde scavenger into the alkylated amino resin, wherein the formaldehyde scavenger is in particular as described hereinbefore.

[0118] According to another advantageous aspect of the disclosure, the methods as described hereinbefore further comprise the step of adsorbing the alkylated amino resin onto a solid carrier material, wherein the solid carrier material is in particular as described hereinbefore.

[0119] According to yet another aspect, the present disclosure relates to a resin composition produced by a process as described hereinbefore, and which has in particular a formaldehyde emission value no greater than 15000 ppm, no greater than 10000 ppm, no greater than 8000 ppm, no greater than 7000 ppm, no greater than 6000 ppm, no greater than 5000 ppm, no greater than 4000 ppm, no greater than 3000 ppm, no greater than 2000 ppm, no greater than 1000 ppm, no greater than 900 ppm, no greater than 800 ppm, no greater than 700 ppm, no greater than 600 ppm, no greater than 500 ppm, no greater than 400 ppm, no greater than 350 ppm, no greater than 300 ppm, no greater than 250 ppm, or even no greater than 200 ppm, when measured according to the test method described in the experimental section.

[0120] Advantageously, the resin composition produced by a process as described hereinbefore has a formaldehyde emission value no greater than 15000 ppm, no greater than 10000 ppm, no greater than 8000 ppm, no greater than 7000 ppm, no greater than 6000 ppm, no greater than 5000 ppm, no greater than 4000 ppm, no greater than 3000 ppm, no greater than 2000 ppm, no greater than 1000 ppm, no greater than 900 ppm, no greater than 800 ppm, no greater than 700 ppm, no greater than 600 ppm, no greater than 500 ppm, or even no greater than 400 ppm, when measured after six month storage according to the test method described in the experimental section.

[0121] According to yet another aspect, the present disclosure relates to the use of a resin composition as detailed above for the manufacturing of (or in) a sulfur-crosslinkable rubber mixture as described hereinbefore.

[0122] According to yet another aspect, the present disclosure relates to the use of a resin composition as detailed above for the manufacturing of (or in) an adhesion promoting-system for a rubber article as described hereinbefore.

[0123] According to yet another aspect, the present disclosure relates to the use of a resin composition as detailed above for the manufacturing of (or in) a reinforcing system for a rubber article as described hereinbefore.

[0124] According to yet another aspect, the present disclosure relates to the use of a resin composition as detailed above for the manufacturing of a crosslinking system, in particular for a sulfur-crosslinkable rubber mixture as described hereinbefore or for a curable (coating) composition as described hereinbefore.

[0125] According to yet another aspect, the present disclosure relates to the use of a resin composition as detailed above for the manufacturing of (or in) a curable (coating) composition as described hereinbefore.

EXAMPLES

[0126] The present disclosure is further illustrated by the following examples. These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims.

[0127] Throughout the present disclosure and example section, the following test and measurement methods are used to characterize the exemplary compositions and their performance attributes.

Test Methods:

A) Total content of methylol groups by HPLC techniques

[0128] The total content of methylol groups in the various resin compositions is determined by using high-performance liquid chromatography (HPLC) techniques. The resin samples are dissolved in methanol (1.0% wt./wt.) and analysed using HPLC equipment Agilent 1100 equipped with a UV detector and a silane-based chromatography column. The total content of methylol groups is determined by suitable identification of the relevant chromatographic monomeric peaks and calculation of their respective areas.

B) Total content of methylol groups by ¹³C-NMR techniques

[0129] The total content (expressed in molar percentage) of methylol groups in the various resin compositions is also determined by using quantitative ¹³C-Nuclear Magnetic Resonance (¹³C-NMR) techniques. The resin samples are dissolved in d⁶-DMSO and analysed using high- field NMR equipment (600 MHz Bruker Avance). The molar percentage of methylol groups per amino N-H functional site is determined, by integrating the ¹³C-signal of the amino compound and the methylol group of the respective resin and then calculating the methylol content using the following formula:

wherein: I(Methylol) is the integrated ¹³C NMR signal of the methylol groups;

I( Amino) = integrated ¹³C NMR signal of the amino compound; and F(Amino) = number of N-H functional site of Amino component

C) Formaldehyde emission analysis

[0130] The formaldehyde emission of the various compositions is measured by using a Micro- Chamber/Thermal Extractor™ instrument (available from Markes International under commercial designation p-CTE™) using the appropriate testing conditions, which are either: a) subjecting the sample to a temperature of 90°C for two hours under dry nitrogen at a flow of 60 mL/min; or b) subjecting the sample to a temperature of 130°C for 30 minutes under dry air at a flow of 60 mL/min. The formaldehyde emissions are then collected into DNPH-silica long cartridges (available from Waters, Sep-Pak DNPH-Silica Plus long cartridge, 800 mg sorbent per cartridge) at the outlet of the emission chamber. Formaldehyde is derivatized in the cartridges into a formaldehyde-DNPH condensate which is extracted from the cartridges with acetonitrile, and then analysed and quantified by reversed phase liquid chromatography equipped with a UV detector using external calibration.

[0131] The formaldehyde emission analysis may be repeated over time after various storage periods to measure the durability of the low formaldehyde emission characteristics of a sample.

D) Curing performance

[0132] The curing performance of the various coating compositions is evaluated using Methyl Ethyl Ketone (MEK) double rub test as described hereinafter. The test is conducted by applying a wet film of the coating composition using 76 micrometers bird type applicator on a Bonderite B1000 cold rolled steel panel and allowed to flash at 23°C for 5 minutes. Subsequently, the wet film is placed in a gradient oven for 30 minutes to undergo curing. The gradient oven is set in the temperature range of 80-168°C with 2°C increment. Once the film is cured, the panel is allowed to cool for one hour at 23°C before initiating the rub test. A IKg ball-peen hammer with cheesecloth wrapped around the hammerhead is used for the test. A total of 200 double rubs are performed along the length of the metal panel while rewetting the cheesecloth with MEK after every 25 double rubs. The minimum temperature at which the film exhibits no marring after 200 rubs is recorded as the full cure temperature. E) Mechanical properties of reinforced sulfur-crosslinked rubber mixtures

[0133] Test samples are made from sulfur-crosslinked rubber mixtures where steel cord (brass plated, mass fraction of Cu in the brass layer: 63%) is embedded into the rubber mixtures. On these test samples, hardness (Shore A) is determined according to ASTM D 2240 at 23°C, and the steel cord adhesion is determined by measuring the force (in N/cm) required to tear out the steel cord wires according to ASTM 2229/D 1871 at 150°C.

Raw materials:

[0134] In the examples, the following raw materials and starting products are used:

Cymel® 303 LF is a monomeric hexamethoxymethyl melamine-based melamine resin, commercially available from Allnex. Referred to hereinafter as CYM-303.

Cymel® 350 is a monomeric methylated melamine resin, commercially available from Allnex. Referred to hereinafter as CYM-350.

Cymel® 327 is a monomeric methylated melamine resin, commercially available from Allnex. Referred to hereinafter as CYM-327.

Cymel® 1123 is a methylated benzoguanamine resin, commercially available from Allnex. Referred to hereinafter as CYM-1123.

Cymel® U-65 is a methylated urea resin, commercially available from Allnex. Referred to hereinafter as CYM-U-65.

Cyrez® 400 is a hexamethoxymethyl melamine-based melamine resin using precipitated silica as a carrier, commercially available from Allnex. Referred to hereinafter as CYR-400.

Sipernat® 45 is a silica carrier material having a neutral pH value, commercially available from Evonik. Referred to hereinafter as SIP-45.

Micro-Cel™ E is a calcium silicate carrier material having a basic pH value, commercially available from Celite Corporation. Referred to hereinafter as CEL-E.

AEPD is 2-amino-2-ethyl- 1,3 -propanediol, commercially available from Sigma-Aldrich.

AHMPD is 2-amino-2-(hydroxymethyl)-l,3-propanediol, commercially available from Sigma- Aldrich.

NH3 is ammonia, commercially available from Sigma-Aldrich. Setalux 27-1597 is an acrylic binder, commercially available from Allnex Belgium. Referred to hereinafter as SET-27.

Cycat 4045 is a blocked acid catalyst, commercially available from Allnex. Referred to hereinafter as CYC-4045.

Alnovol® PN 760/PAST is a modified phenol novolac, commercially available from Allnex. Referred to hereinafter as PN 760.

Examples:

Example 1 : Procedure 1 for the preparation of exemplary resin compositions for use in the following examples.

[0135] The alkylated amino resin is subjected to a thermal treatment between 150°C and 160°C under a reduced (gauge) pressure of about -230 mmHg (70.6 kPa) using parallel conventional thin film evaporators (TFE) and with a residence time of 2 minutes. The resulting composition is used as such or in combination with a formaldehyde scavenger and/or with a solid carrier material.

Example 2: Procedure 2 for the preparation of exemplary resin compositions for use in the following examples.

[0136] The alkylated amino resin is added into a four-neck glass reactor equipped with a stirring shaft, a heating mantel, a condenser, and which is connected to a vacuum line. The resin is gradually heated over a period of 30 minutes until it reaches a temperature of 160°C, while increasing vacuum slowly from a gauge pressure of -400 mmHg (48 kPa) to -720 mmHg (5.3 kPa). The resin is kept under stirring at 160°C under a pressure of -720 mmHg (5.3 kPa) for 10 more minutes before being cooled down. The resulting composition is used as such or in combination with a formaldehyde scavenger and/or with a solid carrier material.

Example 3 : General procedure for the preparation of exemplary liquid resin compositions for use in the following examples.

[0137] The alkylated amino resin (26g) heated at a temperature of 60°C, is added into a four- neck glass reactor equipped with a stirring shaft and a thermometer. Then, the formaldehyde scavenger (lwt.% based on the total weight of the amino resin) is added under continuous stirring. The mixture is stirred for 10 more minutes before being cooled down.

Example 4: General procedure for the preparation of exemplary solid resin compositions for use in the following examples.

[0138] In a four-neck glass reactor equipped with a stirring shaft and a thermometer, 10g of solid carrier material is preloaded. The amino scavenger (lwt.% based on the total weight of the amino resin) and then the alkylated amino resin (26g, heated at a temperature of 60°C) are added under continuous stirring. The mixture is stirred for 10 more minutes before being cooled down.

Example 5: Formulation of exemplary liquid resin compositions (Ex, 1 to Ex, 9) and comparative liquid compositions (Ex, Cl to Ex,C3).

[0139] The exemplary liquid resin compositions and comparative liquid compositions are presented in Table 1 below. Liquid resins compositions of Ex.l to Ex.3 do not comprise a formaldehyde scavenger, whereas the liquid resins compositions of Ex.4 to Ex.9 comprise a formaldehyde scavenger. In Table 1 below are specified the starting alkylated amino resin used, the procedure used for the preparation of the exemplary resin compositions (procedure 1 or 2 together with the temperature used for the thermal treatment), as well as the type and amount of formaldehyde scavenger (in wt.% based on the total weight of the amino resin) used in the exemplary resin compositions. Comparative liquid compositions of Ex. Cl to Ex.C3 are alkylated amino resins which have not been subjected to a thermal treatment under reduced pressure.

Table 1: Formulation of exemplary liquid resin compositions (Ex. l to Ex.9) and comparative liquid compositions (Ex. Cl to Ex.C3).

Table 1 (continued):

Example 6: Formulation of exemplary solid resin compositions (Ex, 10 to Ex, 17) and comparative solid compositions (Ex,C4 to Ex,C6).

[0140] The exemplary solid resin compositions and comparative solid compositions are presented in Table 2 below. The solid resin composition of Ex.10 does not comprise a formaldehyde scavenger, whereas the solid resins compositions of Ex.10 to Ex.17 comprise a formaldehyde scavenger. In Table 2 below are specified the starting alkylated amino resin used, the procedure used for the preparation of the exemplary resin compositions (procedure 1 or 2 together with the temperature used for the thermal treatment), the type and amount of formaldehyde scavenger (in wt.% based on the total weight of the amino resin), as well as the type of solid carrier material used in the exemplary resin compositions. The comparative solid compositions of Ex.C4 to Ex.C6 use alkylated amino resins which have not been subjected to a thermal treatment under reduced pressure. Table 2: Formulation of exemplary solid resin compositions (Ex.10 to Ex.17) and comparative solid compositions (Ex.C4 to Ex.C6).

Table 2 (continued):

Example 7: Total content of methylol groups [0141] The total content of methylol groups (expressed in wt.% based on the total weight of the alkylated amino resin) in various exemplary resin compositions and a comparative composition is determined according to the HPLC test method described hereinbefore. The results are presented in Table 3 below.

Table 3: Total content of methylol groups in various exemplary resin compositions and a comparative composition.

[0142] As can be seen from the results shown in Table 3 above, the total content of methylol groups in resin compositions according to the present disclosure (Ex.l, Ex.2, Ex.8 and Ex.9) is substantially reduced when compared to a resin composition not according to the present disclosure (Ex. Cl). It can further be observed that exemplary resin compositions comprising a formaldehyde scavenger (Ex.8 and Ex.9) provide improved methylol groups content reduction characteristics when compared to exemplary resin compositions not comprising a formaldehyde scavenger (Ex.1 and Ex.2).

Example 8: Formaldehyde emission characteristics of liquid resin compositions

[0143] The formaldehyde emission characteristics (expressed in ppm) of various exemplary liquid resin compositions and comparative liquid compositions are determined according to the test method described hereinbefore using testing conditions a): subjecting the sample to a temperature of 90°C for two hours under dry nitrogen. The results are presented in Table 4 below.

Table 4: Formaldehyde emission characteristics of various exemplary liquid resin compositions and comparative liquid compositions.

[0144] As can be seen from the results shown in Table 4 above, the formaldehyde emission of liquid resin compositions according to the present disclosure (Ex.l, Ex.2 and Ex.4 to Ex.7) is substantially reduced when compared to resin compositions not according to the present disclosure (Ex. Cl to Ex.C3). It can further be observed that exemplary liquid resin compositions comprising a formaldehyde scavenger (Ex.4 to Ex.7) provide improved formaldehyde emission reduction when compared to exemplary liquid resin compositions not comprising a formaldehyde scavenger (Ex.l and Ex.2).

Example 9: Formaldehyde emission characteristics of solid resin compositions

[0145] The formaldehyde emission characteristics (expressed in ppm) of various exemplary solid resin compositions and comparative solid compositions are determined according to the test method described hereinbefore using testing conditions a): subjecting the sample to a temperature of 90°C for two hours under dry nitrogen. The formaldehyde emission measurements are performed after various storage periods (from 0 to 6 months) of the corresponding solid resin compositions at ambient conditions (23 °C, ambient relative humidity of 40%). The results are presented in Table 5 below.

Table 5: Formaldehyde emission characteristics of various exemplary solid resin compositions and comparative solid compositions.

[0146] As can be seen from the results shown in Table 5 above, the formaldehyde emission of solid resin compositions according to the present disclosure (Ex.10 to Ex.13) is substantially reduced when compared to solid resin compositions not according to the present disclosure (Ex.C4 to Ex.C6). It can further be observed that an exemplary solid resin composition comprising a formaldehyde scavenger being a beta-hydroxyamino compound (Ex.12) provides improved formaldehyde emission reduction when compared to an exemplary solid resin composition comprising a formaldehyde scavenger which is not a beta-hydroxyamino compound (Ex.l 1). It is further apparent that an exemplary solid resin composition comprising a solid carrier material having a basic pH value (Ex.13) provides improved formaldehyde emission reduction upon storage when compared to an exemplary solid resin composition comprising a solid carrier material having a neutral pH value (Ex.l 1).

Example 10: Formaldehyde emission characteristics of solid resin compositions

[0147] The formaldehyde emission characteristics (expressed in ppm) of various exemplary solid resin compositions and a comparative solid composition are determined according to the test method described hereinbefore using testing conditions a): subjecting the sample to a temperature of 90°C for two hours under dry nitrogen. The results are presented in Table 6 below.

Table 6: Formaldehyde emission characteristics of various exemplary solid resin compositions and a comparative solid composition.

[0148] As can be seen from the results shown in Table 6 above, the formaldehyde emission of solid resin compositions according to the present disclosure (Ex.14 to Ex.17) is substantially reduced when compared to a solid resin composition not according to the present disclosure (Ex.C4). It can further be observed that exemplary solid resin compositions comprising AHMPD as a formaldehyde scavenger (Ex.16 and Ex.17) provide improved formaldehyde emission reduction when compared to exemplary solid resin composition comprising AEPD as a formaldehyde scavenger (Ex.14 and Ex.15).

Example 11 : Formaldehyde emission characteristics of coating compositions

[0149] Various exemplary coating compositions and a comparative coating composition are prepared by combining the various liquid resin compositions (27 parts by weight) with acrylic binder SET-27 (73 parts by weight) and 1.5 wt.% of acid catalyst CYC-4045 (based on the total solid weight of the coating composition). The coating compositions are then coated and thermally cured according to the procedure detailed in the test method described hereinbefore.

[0150] The formaldehyde emission characteristics (expressed in ppm) of the various exemplary coating compositions and the comparative coating composition are determined according to the test method described hereinbefore using testing conditions b): subjecting the sample to a temperature of 130°C for 30 minutes under dry air. The results are presented in Table 7 below. In Table 7 are specified the corresponding alkylated amino resins used for the preparation of the exemplary coating compositions and the comparative coating composition.

Table 7: Formaldehyde emission characteristics of various exemplary coating compositions and a comparative coating composition.

[0151] As can be seen from the results shown in Table 7 above, the formaldehyde emission of coating compositions according to the present disclosure (Ex.5 to Ex.9) is substantially reduced when compared to a coating composition not according to the present disclosure (Ex. Cl). It can further be observed that higher contents of a formaldehyde scavenger in the exemplary coating compositions advantageously improve the formaldehyde emission reduction characteristics.

Example 12: Curing performance of coating compositions

[0152] Various exemplary coating compositions and a comparative coating composition are prepared as described in Example 11 above. The curing performance (expressed in °C for achieving full cure) of the various exemplary coating compositions and the comparative coating composition are determined according to the test method described hereinbefore. The results are presented in Table 8 below. In Table 8 are specified the corresponding alkylated amino resins used for the preparation of the exemplary coating compositions and the comparative coating composition.

Table 8: Curing performance of various exemplary coating compositions and a comparative coating composition.

[0153] As can be seen from the results shown in Table 8 above, the curing performance of coating compositions according to the present disclosure (Ex.3, Ex.5 and Ex.7) are very much on par with the curing performance of a coating composition obtained with a conventional resin composition (Ex. Cl). It can further be observed that the addition of a formaldehyde scavenger in the exemplary coating compositions does not detrimentally affect the curing performance. This is particularly surprising finding considering that the added formaldehyde scavenger are amine compounds, which are generally expected to reduce the curing performance.

Example 13: Mechanical properties of reinforced crosslinked rubber mixtures

[0154] An exemplary reinforced sulfur-crosslinked rubber mixture and a comparative reinforced sulfur-crosslinked rubber mixture are prepared by combining the solid resin compositions (3 parts per hundred rubber, phr) with phenol novolac resin PN 760 (3 parts per hundred rubber), sulphur (4 parts per hundred rubber), and the base rubber mixture 1 and additional additives described in Example 3 of US 2012/0095152 Al (Schafer et al.).

[0155] The test samples are made and tested for mechanical properties according to the test methods described hereinbefore. The results are presented in Table 9 below. In Table 9 are specified the corresponding solid resin compositions used for the preparation of the exemplary reinforced sulfur-crosslinked rubber mixture and the comparative reinforced sulfur-crosslinked rubber mixture.

Table 9: Mechanical properties of an exemplary crosslinked rubber mixture and a comparative crosslinked rubber mixture.

[0156] As can be seen from the results shown in Table 9 above, the mechanical properties of a reinforced crosslinked rubber mixture obtained with a solid resin composition according to the present disclosure (Ex.16) are very much on par with the mechanical properties of a reinforced crosslinked rubber mixture obtained with a conventional solid resin composition.

Example 14: Formulation of exemplary liquid resin compositions (Ex, 18 to Ex, 22) and comparative liquid compositions (Ex,C7 to Ex, Cl 1).

[0157] The exemplary liquid resin compositions and comparative liquid compositions are presented in Table 10 below. In Table 10 below are specified the starting alkylated amino resin used, the procedure used for the preparation of the exemplary resin compositions (procedure 1 or 2 together with the temperature used for the thermal treatment). Comparative liquid compositions of Ex.C7 to Ex. Cl 1 are alkylated amino resins which have not been subjected to a thermal treatment under reduced pressure. Table 10: Formulation of exemplary liquid resin compositions (Ex.18 to Ex.22) and comparative liquid compositions (Ex.C7 to Ex.Cl 1).

Table 10 (continued):

Example 15: Total content of methylol groups

[0158] The total content of methylol groups (expressed in molar percentage of methylol groups per amino N-H functional site) in various exemplary resin compositions and comparative compositions is determined according to the ¹³C-NMR test method described hereinbefore. The results are presented in Table 11 below.

Table 11 : Total content of methylol groups in various exemplary resin compositions and comparative compositions.

Table 11 (continued): Total content of methylol groups in various exemplary resin compositions and comparative compositions.

[0159] As can be seen from the results shown in Table 11 above, the total content of methylol groups in resin compositions according to the present disclosure (Ex.18 to Ex.22) is substantially reduced when compared to resin compositions not according to the present disclosure (Ex.C7 to Ex. Cl 1). Example 16: Formaldehyde emission characteristics of liquid resin compositions

[0160] The formaldehyde emission characteristics (expressed in ppm) of various exemplary liquid resin compositions and comparative liquid compositions are determined according to the test method described hereinbefore using testing conditions a): subjecting the sample to a temperature of 90°C for two hours under dry nitrogen. The results are presented in Table 12 below.

Table 12: Formaldehyde emission characteristics of various exemplary liquid resin compositions and comparative liquid compositions.

[0161] As can be seen from the results shown in Table 12 above, the formaldehyde emission of liquid resin compositions according to the present disclosure (Ex.19 to Ex.22) is substantially reduced when compared to resin compositions not according to the present disclosure (Ex.C8 to Ex.Cl l). s

Claims

1. A resin composition comprising an alkylated amino resin which is the reaction product of an amino compound, formaldehyde and an alcohol, wherein the resin composition is obtained by subjecting the alkylated amino resin to a thermal treatment under reduced pressure, thereby reducing the total content of methylol groups in the alkylated amino resin.

2. A resin composition according to claim 1, which has a total content of methylol groups no greater than 4.0 wt.%, no greater than 3.5 wt.%, no greater than 3.0 wt.%, no greater than 2.5 wt.%, no greater than 2.0 wt.%, or even no greater than 1.5 wt.%, based on the total weight of the alkylated amino resin.

3. A resin composition according to any one of claim 1 or 2, which has a total content of methylol groups in a range from 0.5 to 4.0 wt.%, from 0.5 to 3.5 wt.%, from 0.5 to 3.0 wt.%, from 1.0 to 3.0 wt.%, from 1.0 to 2.5 wt.%, or even from 1.0 to 2.0 wt.%, based on the total weight of the alkylated amino resin.

4. A resin composition according to any one of the preceding claims, wherein the alkylated amino resin is subjected to a thermal treatment at a temperature in a range from 130 to 180°C, from 130 to 170°C, from 140 to 170°C, from 140 to 165°C, from 145 to 165°C, or even from 150 to 160°C.

5. A resin composition according to any one of the preceding claims, wherein the alkylated amino resin is subjected to a thermal treatment at a pressure in a range from 100 to 0 kPa, from 95 to 1.5 kPa, from 90 to 1.5 kPa, from 75 to 1.5 kPa, from 60 to 1.5 kPa, from 55 to 1.5 kPa, from 50 to 1.5 kPa, or even from 35 to 1.5 kPa.

6. A resin composition according to any one of the preceding claims, wherein the alkylated amino resin comprises alkoxymethyl derivatives of melamine, alkoxymethyl derivatives of benzoguanamine, and any mixtures thereof.

7. A resin composition according to any one of the preceding claims, which further comprises a formaldehyde scavenger.

8. A resin composition according to claim 7, wherein the formaldehyde scavenger is selected from the group consisting of amino alcohols, urea, ethylene urea, ammonia, and any combinations or mixtures thereof.

9. A resin composition according to any one of the preceding claims, which is adsorbed onto a solid carrier material.

10. A sulfur-crosslinkable rubber mixture comprising a rubber component and a resin composition according to any one of claims 1 to 9.

11. A curable composition comprising a resin composition according to any one of claims 1 to 9.

12. A method for reducing the formaldehyde emission of an alkylated amino resin, wherein the method comprises the steps of: a) providing an alkylated amino resin which is the reaction product of an amino compound, formaldehyde and an alcohol; and b) subjecting the alkylated amino resin to a thermal treatment under reduced pressure, thereby reducing the total content of methylol groups in the alkylated amino resin.

13. A method according to claim 12, which further comprises the step of subjecting the alkylated amino resin to a re-alkylation treatment of the methylol groups.

14. Use of a resin composition according to any one of claims 1 to 9 for the manufacturing of a sulfur-crosslinkable rubber mixture.

15. Use of a resin composition according to any one of claims 1 to 9 for the manufacturing of a curable composition, in particular a curable coating composition.