RU2717938C1 - Protective epoxy compositions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a curable multicomponent epoxy composition used to obtain protective coatings, preferably for producing coatings of the inner surface of pipes of oil and gas pipelines, as well as to a substrate containing a coating, a method of producing a coating and use of alkylphenol. Epoxide composition contains epoxy resin, an amine-containing curing agent and a curing catalyst. Amine-containing curing agent is polyesteramidoamine. Curing catalyst used is alkylphenol to accelerate curing of the epoxide composition. Alkylphenol is monoalkylphenols, dialkylphenol or a trialkylphenol containing alkyl group selected from linear or branched saturated C₁-C₈ alkyls. Substrate contains a coating obtained by curing said composition. Method of producing a coating on the surface of a substrate involves obtaining the above curable composition, then applying a mixture of the first and second parts of the curable composition on the surface of the substrate, then the epoxide composition is cured.

EFFECT: invention increases rate of hardening of the composition at low temperatures.

19 cl, 1 tbl, 9 ex

Description

State of the art

Currently, many oil and gas pipelines are either left unprotected or, alternatively, a protective coating is applied to the surface of the pipe to protect the pipeline during storage, construction and operation. Such a protective coating often contains a thin film epoxy coating or a fused epoxy coating.

Coating compositions containing an epoxy resin in combination with a curing agent or hardener, usually an amine-containing compound, are commercially used for this purpose, and various compositions are described in the art, for example, in EP 0999245 A1; EP 0379107 A2 and EP 2495271 A1. In particular, when applying epoxy resins as protective coatings to oil and gas pipelines, rapid curing is required at low temperatures, since it is often necessary to apply epoxy resins to the pipes in place, and access to heating equipment is difficult. Catalysts may be added to the epoxy compositions to accelerate the cure rate. Nitrate salts and combinations of nitrate salts with aminomethylphenols or dihydroxyphenols, for example, in EP 0471988 A1, EP 0327039 B1, US 5573819 and EP 1973959 have been described as catalysts.

However, there is still a need for catalysts for epoxy coating compositions that provide rapid cure at low temperatures. Preferably, such compositions are suitable for protective coatings on oil and gas pipes.

Short description

Accordingly, in one aspect of the present description, there is provided a curable multicomponent epoxy coating composition comprising an epoxy resin, an amine-containing curing agent and a curing catalyst, wherein said composition comprises a curing agent in a first part and an epoxy resin in a second part, separately from said first part, and where the curing catalyst is an alkyl phenol selected from monoalkyl phenols, dialkyl phenols and trialkyl phenols containing an alkyl group selected from non-developed branched or branched, saturated and olefinically unsaturated C ₁ -C ₈ alkyls.

In another aspect of the present description, there is provided a substrate comprising a coating obtained by curing a curable composition.

In another aspect of the present disclosure, the use of an alkyl phenol selected from monoalkyl phenols, dialkyl phenols and trialkyl phenols containing an alkyl group selected from unbranched or branched, saturated and olefinically unsaturated C ₁ -C ₈ alkyls to accelerate the curing of the curable epoxy composition is provided.

In another aspect of the present description, a method for coating the surface of a substrate, in particular the inner surface of a pipe or pipe, is provided, comprising the steps of

(i) providing a curable composition,

(ii) applying a mixture of the first and second parts of the curable composition to a substrate, preferably by spraying, brushing, painting, dipping, spraying, applying with a knife device, applying with a roller, applying with a strip or combinations, and

(iii) providing curing of the curable composition.

Detailed description

Before any implementation options for the present description will be explained in detail, it should be understood that the application of the present description is not limited to the structural details and arrangement of components set forth in the following description. The present invention allows for other options for implementation and practical application or implementation in various ways. In addition, it should be understood that the phraseology and terminology used in the present description are intended for the purpose of description and are not limiting. In contrast to the use of "consisting", the use of "including", "containing" or "having" and their variants implies the inclusion of the elements listed after these terms and their equivalents, as well as additional elements. Using the indefinite singular form means one or more. Any numerical range described herein includes all values from a lower value to an upper value of this range. For example, a concentration range of 1% to 50% represents a reduction and explicitly discloses values between 1% and 50%, such as, for example, 2%, 40%, 10%, 30%, 1.5%, 3.9% and so on.

Curable Compositions

Curable compositions according to the present description contain at least one epoxy resin and at least one amine-containing curing agent containing at least one primary or secondary amino group. The amine-containing curing agent reacts with the oxirane group of the epoxy resin and cross-cures (cures) the epoxy resin. Curable compositions further comprise at least one curing catalyst that accelerates the curing reaction. The cured composition can be used, for example, as a protective coating.

Due to the reactivity of the components, curable compositions according to the present description are usually provided in the form of two or more parts, where the first part contains an epoxy resin and the other, second part contains one or more curing agents. Both parts are mixed before use.

The catalyst and other optional components may be included in the first part, in the second part, or both in the first part and in the second part.

Preferably, the curable composition according to the present description has a low viscosity and can be applied by spraying on the surface to be coated. Preferably, the surface is a pipe surface, preferably an inner surface of a pipe, preferably an oil or gas pipe. Accordingly, low viscosity epoxies and liquid curing agents are preferably used.

Catalysts

Curable compositions according to the present description contain one or more alkyl phenols selected from mono-, di - or trialkylphenols. Preferably, the alkyl phenols are dialkyl phenols or monoalkyl phenols, more preferably they are monoalkyl phenols. Preferably, the catalyst contains an alkyl group containing from 1 to 8 carbon atoms, more preferably from 3 to 8 carbon atoms. Preferably, all alkyl groups of the catalyst contain from 1 to 8 carbon atoms, preferably from 3 to 8 carbon atoms. Preferably, the alkyl group is branched and, more preferably, all of the alkyl groups of the catalyst are branched. The alkyl group may be olefinically unsaturated, that is, it may contain one or more C — C double bonds, but preferably, the alkyl group is saturated and, more preferably, all of the alkyl groups of the catalyst are saturated.

Preferably, the alkyl phenol is selected from the group consisting of tert-butylphenol, sec-butylphenol, tert-amylphenol, isopropylphenol, and combinations thereof.

Specific examples of catalysts include 4-tert-butylphenol, 2-tert-butylphenol, 4-tert-amylphenol, 4-sec-butylphenol (shown in Formula I).

Additional specific examples include, but are not limited to, 2,4-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,4-di-tert-amylphenol, 2,4-di-sec-butylphenol, 4,6-di-tert-butylphenol, 2,6-di-tert-butylphenol, 4,6-di-terete-amylphenol, 4,6-di-tert-butylphenol; 2-methyl-4-tert-butylphenol, 2-methyl-4-tert-amylphenol, 2-methyl-4-sec-butylphenol; 6-methyl-4-tert-butylphenol, 6-methyl-2-tert-butylphenol, 6-methyl-4-tert-amylphenol, 6-methyl-4-sec-butylphenol, 3-methyl-4-tert-butylphenol, 3-methyl-2-tert-butylphenol, 3-methyl-4-tert-amylphenol, 3-methyl-4-tert-butylphenol, 2-ethyl-4-tert-amylphenol, 2-ethyl-4-tert-butylphenol; 6-ethyl-4-tert-butylphenol, 6-ethyl-2-tert-butylphenol, 6-ethyl-4-tert-amylphenol, 6-ethyl-4-sec-butylphenol, 3-ethyl-4-tert-butylphenol, 3-ethyl-2-tert-butylphenol, 3-ethyl-4-tert-amylphenol, 3-ethyl-4-sec-butylphenol, 2-propyl-4-tert-amylphenol, 2-propyl-4-sec-butylphenol; 6-propyl-4-tert-butylphenol, 6-propyl-2-tert-butylphenol, 6-propyl-4-tert-amylphenol, 6-propyl-4-sec-butylphenol, 3-propyl-4-tert-butylphenol, 3-propyl-2-tert-butylphenol, 3-propyl-4-tert-amylphenol, 3-propyl-4-tert-butylphenol, 6-propyl-4-tert-butylphenol, 6-propyl-2-tert-butylphenol, 6-propyl-4-tert-amylphenol, 6-propyl-4-sec-butylphenol, 3-propyl-4-tert-butylphenol, 3-propyl-2-tert-butylphenol, 3-propyl-4-tert-amylphenol, 3-propyl-4-tert-butylphenol, where the propyl residues include n-propyl and isopropyl groups.

Alkylphenols can be used to accelerate the curing reaction of the curable epoxy composition, i.e., by combining reactive epoxy and amine-containing components. Since alkyl phenols can be used to accelerate the curing reaction between reactive components, they are also referred to herein as “catalysts” or “curing catalysts”. A mixture of alkyl phenol catalysts and a combination of alkyl phenol catalysts as described herein with other known catalysts can be used to cure the epoxy compositions.

Epoxy resins

The epoxy resin included in the first part contains at least one epoxy functional group (i.e., an oxirane group) per molecule. This terminal oxirane group is often part of a glycidyl group. A fragment of an epoxy resin molecule that is not an oxirane group (i.e., an epoxy resin molecule without oxirane groups) may be aromatic, aliphatic or a combination thereof, and may be unbranched, branched, cyclic, or a combination thereof. Aromatic and aliphatic epoxy fragments may contain heteroatoms or other groups that do not react with oxirane groups. That is, the epoxy resin may contain halogen groups, hydroxy groups, such as in an ether linking group, thio groups, such as in a thioether linking group, carbonyl groups, carbonyloxy groups, carbonylimino groups, phosphono groups, sulfono groups, nitro groups, nitrile groups and the like. The epoxy resin may also be a silicon-based material, such as a polydiorganosiloxane-based material.

In preferred embodiments, the epoxy resin is glycidyl ether. Typical glycidyl ethers are represented by formula (II):

In the formula (II), the R ⁴ group is a p-valent group which is aromatic, aliphatic or a combination of both aliphatic and aromatic units. Despite the fact that the variable p can be any suitable integer greater than or equal to 1, preferably p is an integer in the range from 2 to 4.

In some preferred epoxy resins of formula (II), the variable p is 2, i.e. the epoxy resin is diglycidyl ether. The remainder of R ⁴ in the formula (II) may contain (a) an arylene group or (b) an arylene group in combination with alkylene, heteroalkylene, or both. Such epoxy resins can be obtained, for example, by reacting an aromatic compound containing at least two hydroxyl groups with an excess of epichlorohydrin. Many commercially available diglycidyl ethers of the formula (II) epoxy resin are prepared from bisphenol A (i.e., bisphenol A is 4,4'-dihydroxydiphenylmethane). Examples include, but are not limited to, epoxies available under the trade name EPON (e.g., EPON 828, EPON 872 and EPON 1001) from Hexion Specialty Chemicals, Inc. in Houston, Texas, epoxies available under the trade name DER (e.g., DER 331, DER 332 and DER 336) from Dow Chemical Co. in Midland, MI, and epoxies available under the trade name EPICLON (e.g., EPICLON 850) from Dainippon Ink and Chemicals, Inc. in Chiba, Japan. Other commercially available diglycidyl ether epoxy resins are derived from bisphenol F (i.e., bisphenol F is 2,2'-dihydroxydiphenylmethane). Examples include, but are not limited to, epoxies available under the trade name DER (e.g. DER 334) from Dow Chemical Co., and epoxies available under the trade name EPICLON (e.g. EPICLON 830) from Dainippon Ink and Chemicals, Inc . Other commercially available diglycidyl ether ether epoxy resins of formula (II) are mixtures of epoxy resins derived from bisphenol A and bisphenol F (e.g. DER 353 from Dow Chemical Co.).

Although epoxy resins derived from bisphenol A or bisphenol F are commercially available and preferred, other suitable aromatic compounds containing at least two hydroxyl groups may be used. Examples include, but are not limited to, resorcinol, catechin, hydroquinone, p, p'-dihydroxydibenzyl, p, p'-dihydroxyphenylsulfone, p, p'-dihydroxybenzophenone, 2,2'-dihydroxyphenylsulfone and p, p'-dihydroxybenzophen. Other examples include 2,2 '2,3', 2,4 ', 3,3', 4,4 'and 3,4' isomers digidroksidifenildimetilmetana, digidroksidifeniletilmetilmetana, digidroksidifenilmetilpropilmetana, digidroksidifeniletilfenilmetana, digidroksidifenilpropilenfenilmetana, digidroksidifenilbutilfenilmetana, digidroksidifeniltoliletana, digidroksidifeniltolilmetilmetana, and digidroksidifenilditsiklogeksilmetana dihydroxydiphenylcyclohexane. Additional examples include 2,3 ', 2,4', 3,3 ', and 3,4' isomers of dihydroxydiphenylmethane.

Other examples of epoxy resins may be considered, including those described in EP 2495271 A1.

Although the epoxy resin may have any suitable molecular weight, the weight average molecular weight is usually at least 100 g / mol, at least 150 g / mol, at least 175 g / mol, at least 200 g / mol at least 250 g / mol or at least 300 g / mol. In the case of polymeric epoxies, the weight average molecular weight can be up to 50,000 g / mol or even more. The weight average molecular weight is often up to 40,000 g / mol, up to 20,000 g / mol, up to 10,000 g / mol, up to 5,000 g / mol, up to 3,000 g / mol or up to 1,000 g / mol. For example, the weight average molecular weight may be in the range of 100 to 50,000 g / mol, in the range of 100 to 20,000 g / mol, in the range of 10 to 10,000 g / mol, in the range of 100 to 5,000 g / mol, in the range of 200 to 5000 g / mol, in the range from 100 to 2000 g / mol, in the range from 200 to 2000 g / mol, in the range from 100 to 1000 g / mol, or in the range from 200 to 1000 g / mol.

Suitable epoxy resins are typically liquid at room temperature (for example, from about 20 ° C to about 25 ° C). However, epoxy resins that can be dissolved in a suitable solvent may also be used.

The epoxy resin may be a mixture of epoxy compounds. For example, epoxy resins can be selected so that they are a mixture of epoxides that provides the desired viscosity or flow characteristics before curing. The mixture may contain at least one first epoxy resin, called a reactive diluent, which has a lower viscosity, and at least one second epoxy resin, which has a higher viscosity. A reactive diluent helps reduce the viscosity of the epoxy resin mixture and often contains either a branched backbone that is saturated or a cyclic backbone that is saturated or unsaturated. Examples of reactive diluents include, but are not limited to, resorcinol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, and trimethylolpropane triglycidyl ether. Diglycidyl ethers of cyclohexanedimethanol are commercially available under the trade name HELOXY MODIFIER 107 from Hexion Specialty Chemicals in Columbus, Ohio, USA and under the trade name EPODIL 757 from Air Products and Chemical Inc. in Allentown, PA, USA. Other reactive diluents contain only one functional group (i.e., an oxirane group), for example, various monoglycidyl ethers. Some typical monoglycidyl ethers include, but are not limited to, alkyl glycidyl ethers with an alkyl group containing from 1 to 20 carbon atoms, from 1 to 12 carbon atoms, from 1 to 8 carbon atoms, or from 1 to 4 carbon atoms. Some typical monoglycidyl ethers are commercially available under the trade name EPODIL from Air Products and Chemical, Inc. in Allentown, PA, USA such as EPODIL 746 (2-ethylhexyl glycidyl ether), EPODIL 747 (aliphatic glycidyl ether) and EPODIL 748 (aliphatic glycidyl ether).

Curable composition in accordance with the present description usually contains at least 20 mass. % epoxy based on the total weight of the first part and second part (i.e., based on the total weight of the curable composition). For example, the curable composition may contain at least 25 mass. %, at least 30 mass. %, at least 40 mass. % or at least 50 mass. % epoxy. Curable composition may, for example, contain up to 55 mass. % epoxy.

Curing agent

When mixing the curing agent with an epoxy resin, the amino groups of the curing agent react with the oxirane groups of the epoxy resin, which leads to curing of the composition. Suitable curing agents include amine based curing agents known in the art.

Curing agents typically contain at least two primary amino groups, at least two secondary amino groups, or combinations thereof. That is, the curing agent contains at least two groups of the formula —NRH, where R is selected from hydrogen, alkyl, aryl or alkylaryl. Suitable alkyl groups often contain from 1 to 12 carbon atoms, from 1 to 8 carbon atoms, from 1 to 6 carbon atoms, or from 1 to 4 carbon atoms. The alkyl group may be cyclic, branched, unbranched or a combination thereof. Suitable aryl groups typically contain from 6 to 12 carbon atoms, for example a phenyl group. Suitable alkylaryl groups can be either alkyl substituted with aryl or aryl substituted with alkyl. Aryl and alkyl groups discussed above can be used in alkylaryl groups.

A curing agent without at least two amino groups (i.e., a fragment of a curing agent that is not an amino group) may be any suitable aromatic group, aliphatic group, or a combination thereof. Examples include, but are not limited to, alkylene groups and heteroalkylene groups, or combinations thereof. Suitable alkylene groups often contain from 1 to 18 carbon atoms, from 1 to 12 carbon atoms, from 1 to 8 carbon atoms, from 1 to 6 carbon atoms, or from 1 to 4 carbon atoms. Suitable heteroalkylene groups contain at least one hydroxy, thio or —NH— group located between two alkylene groups. Suitable heteroalkylene groups often contain from 2 to 50 carbon atoms, from 2 to 40 carbon atoms, from 2 to 30 carbon atoms to 20 carbon atoms or from 2 to 10 carbon atoms with up to 20 heteroatoms, up to 16 heteroatoms, up to 12 heteroatoms or up to 10 heteroatoms. Hetero atoms are often hydroxy groups. Specific examples of curing agents include, but are not limited to, ethylenediamine, diethylenediamine, diethylene triamine, triethylenetetramine, propylene diamine, tetraethylene pentamine, hexaethylene heptamine, hexamethylene diamine, 2-methyl-1,5-pentamethylenediamine, 1-amino-3-3,5-amino-3-3,5-amine-3-amino trimethylcyclohexane (also called isophorondiamine), aminoethylpiperazine and the like. Other examples of amino-curing agents with heteroalkylene groups include, but are not limited to, aminoethyl piperazine, 4,7,10-trioxo tridecane-1,13-diamine (TTD), available from TCI America in Portland, Oregon, or poly (alkylene oxide) diamines (also called polyether diamines) such as poly (ethylene oxide) diamine, poly (propylene oxide) diamine or a copolymer thereof.

Curing agents preferably include polyetheramines and polyetheramido amines. Polyetheramines include diamines which are separated by a group containing at least one polyester unit. For example, polyetheramines may contain oxyethylene or oxypropylene or oxyethylene-oxypropylene backbones and include poly (ethylene oxide) diamines, poly (propylene oxide) diamines and their copolymer, for example, poly (ethylene oxide-propylene oxide) diamine. Such polyetheramines are commercially available, for example, under the trade name JEFFAMINE® from Huntsman. Diamines with repeating hydroxypropylene units in the backbone are available as the JEFFAMINE® D series, for example, D-230, D-400, D-2000 and D-4000, with the number indicating the approximate molecular weight of the corresponding substance.

Polyetheramido amines include compounds corresponding to the formula (III), (IV), (V) and (VI):

where x: 1-200, y: 0-200, z: from 1 to 100, m, n: from 0 to 2, m + n≥: 0.1, Rb = monovalent primary aliphatic or aromatic residue or amino residue, in in particular, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl radical, or ethylamine, n-propylamine, iso-propylamine, n-butylamine, sec-butylamine or tert-butylamine;

where x: 1-200, y: 0-200, z: from 1 to 100, m, n: from 0 to 2, m + n> 0.1, or the general formula IV or VI:

where x: 1-200, y: 0-200, z: from 1 to 100, m, n: from 0 to 2, m + n> 0.1; and

where x, y, z: 1-200, n: from 1 to 100, m≥0.1.

Such polyetheramido amines and their preparation are described in EP 2495271 A1, incorporated herein by reference.

Curing agents are preferably chosen to provide liquid curable epoxy compositions having a low viscosity (at 25 ° C). Curing agents may be mixtures of one or more curing agents.

Curing agents are usually used in suitable amounts to achieve curing. It depends on the number of amino groups and epoxy groups (oxiranes). For example, if a diamine-containing curing agent is used for curing with a diglycidyl ether epoxy resin, said curing agent may be used in a molar excess, usually with a molar ratio of diamine to epoxy resin of 2.5: 1, or even 3: 1, or even more than 3.5: 1. However, a molar excess of epoxy can also be used.

Curable compositions in accordance with the present description may optionally also contain one or more secondary curing agents. Curing agents, commonly regarded as secondary curing agents, are diamines that are not highly reactive with the oxirane rings of epoxy resins at room temperature. These secondary curing agents are often cyclic aliphatic amines or aromatic amines. Examples include imidazoles and their salts, imidazolines and their salts, aminoalkyl substituted piperazines and morpholines and phenols substituted with tertiary amino groups. In case of application, typical amounts of secondary curing agents are up to 6 mass. %, up to 5 mass. % or up to 4 wt. % based on the total weight of the curable composition.

Additives

Curable compositions according to the present description may contain additional optional components. Such optional components are fillers. Fillers may be added to the first part of the curable composition, to the second part of the curable composition, or to both the first part and the second part of the curable composition. Fillers are often added to increase adhesion, to improve corrosion resistance, to control the rheological properties of the composition, to reduce shrinkage during curing, to accelerate curing, to absorb contaminants, to improve heat resistance, to eliminate surface defects or surface tension, or to combine the above. The fillers may be inorganic material, organic materials or composite materials containing both inorganic and organic materials. Suitable excipients include silica gels, silicates, clay, talc, calcium phosphates, calcium molybdates, calcium carbonate, calcium hydroxide, fumed silica, organoclay, aluminum trihydrates, magnesium dihydrates, glass microspheres, hollow glass microspheres, polymer microspheres and hollow polymer microspheres. Fillers include pigments such as iron oxide, brick dust, carbon black, titanium oxide and the like. The surface of any of these fillers can be modified to make them more compatible with the curable or cured composition.

Typical amounts of filler include amounts from 0.01 to 50 mass. % based on the total weight of the curable composition (first and second parts combined) depending on the desired use of the curable composition and the desired properties of the filler.

Curable compositions in accordance with the present invention may contain additional optional ingredients, for example, at least one substance selected from the group consisting of reactive liquid modifiers, reactive diluents, oil displacing agents, corrosion inhibitors, antioxidants, plasticizers, stabilizers, molecular sieves, rheological modifiers properties and other accelerators known in the art as suitable additives for curable epoxy composites ozitsy including, for example, additives described in EP 2495271 A1. In the Examples section, a comparison of experimental solutions of epoxides additionally containing inorganic phosphate (3 wt.%) With solutions not containing inorganic phosphate salts showed an additional increase in the chemical resistance (corrosion resistance) of the cured composition.

If the composition is in the form of two parts, these additional substances may be present in the first and / or second part.

Methods for the preparation and use of curable compositions

The various parts of the curable composition are mixed together and cured to form a cured composition. These parts are usually mixed together immediately prior to use of the curable composition. The amount of each part added to the mixture can be selected so as to provide the desired molar ratio of the oxirane groups to the amine hydrogen atoms.

Curable compositions can be provided that can be cured at room temperature, but, alternatively or additionally, they can be cured at elevated temperature, which typically speeds up curing. Curable compositions can be used as adhesive substances or as protective coatings, preferably as coating compositions for coating the inner surface of oil and gas pipelines.

The present invention also relates to a method for coating a substrate, in particular a pipe or pipe surface, preferably an inner surface, comprising the steps of providing a curable composition in accordance with the present description, at least partially coating the surface of a substrate with a curable composition, and curing the curable composition . The curable composition can be applied to the surface of the substrate using a brush, by spraying, dyeing, dipping, dipping, using a knife device, using a roller, using a bar. Preferably, the curable compositions have a low viscosity and can be sprayed onto the surface to be coated. If the curable composition is used as a two-part composition, the step of providing the curable composition comprises the step of mixing the first and second parts of the curable composition in an appropriate ratio.

The objects and advantages of the present description are additionally illustrated by the following examples, but the specific materials and quantities indicated in these examples, as well as other conditions and details, do not limit the present description to the materials and quantities used in the examples. These examples are provided for illustrative purposes only.

Examples

In examples 1-8, epoxy compositions with various alkyl phenol catalysts in various quantities were obtained (cat.1-6) by placing an amine-containing hardener (polyetheramidoamine obtained in accordance with EP 2495271 A1, equiv. Col. 85) in a 125 ml vessel and mixing it with catalysts. An epoxy component (DER 353 from Dow Chemical Co. (bisphenol A / F epoxy resin modified with C ₁₂ -C ₁₄ aliphatic glycidyl ether), equiv. Mass. 195) was added in 1 portion and the resulting mixture was thoroughly mixed with a wooden spatula for 2 minutes while avoiding air entrapment. As a result of the components entering the reaction, the viscosity of the mixture increased with time, and heat was generated (exothermic effect). The mixture was periodically mixed with a wooden spatula so that it remained homogeneous.

The time from the start of adding the epoxy component to the point where dripping was no longer visually observed (corresponding to a viscosity of about 10,000 mPa⋅s or higher; Brookfield LVDV-II + Pro viscometer equipped with an S63 spindle with a rotation speed of 12 rpm) was determined as visual viability time. Visual pot life is an indicator of the cure rate of a composition. The shorter the pot life, the faster the composition cures. The ingredients used to obtain the compositions and the results of the visual determination of the pot life are shown in table 1.

In the comparative example, the procedure described above was carried out, except that no catalyst was added.

As shown in Table 1, the addition of short chain alkyl phenols to epoxy compositions significantly reduces the visual pot life and thus increases the cure rate. Monoalkylphenols were more effective in terms of increasing cure rate than dialkylphenols. Dialkylphenols with alkyl substituents at the para position (2,4-dialkyl phenols) were more effective than with substituents at the ortho position (2,6-dialkyl phenols).

List of Specific Illustrative Embodiments

For the purpose of further illustration, the following is a list of some illustrative embodiments. This list is intended to illustrate the present description without limiting the present description to the illustrative embodiments listed therein.

1. A curable multicomponent epoxy coating composition comprising an epoxy resin, an amine-containing curing agent, and a curing catalyst, wherein said composition contains a curing agent in a first part and an epoxy resin in a second part, separately from said first part, and wherein the curing catalyst is an alkyl phenol, selected from monoalkylphenols, dialkylphenols and trialkylphenols containing an alkyl group selected from unbranched or branched, saturated and olefinically unsaturated s C ₁ -C ₈ alkyls.

2. Curable composition according to illustrative embodiment 1, wherein the alkyl group is a saturated C ₃ -C ₈ alkyl group.

3. A curable composition according to an exemplary embodiment 1 or 2, wherein the alkyl group is saturated and branched.

4. Curable composition according to any one of illustrative embodiments 1-3, wherein the alkyl group is monoalkylphenol.

5. The curable composition according to any one of illustrative embodiments 1-4, wherein the alkyl phenol is selected from the group consisting of tert-butylphenol, sec-butylphenol, tert-amylphenol, isopropylphenol, and combinations thereof.

6. Curable composition according to any one of illustrative embodiments 1-5, where the epoxy resin is diglycidyl ether, corresponding to the General formula

where R ⁴ represents a p-valent group that is aromatic, aliphatic or is a combination of both aliphatic and aromatic units, and p is an integer greater than or equal to 1, preferably p is an integer in the range from 2 to 4, more preferably p is 2.

7. A curable composition according to any one of illustrative embodiments 1-6, wherein the epoxy resin is diglycidyl ether containing units derived from bisphenol A or bisphenol F, or a combination thereof.

8. A curable composition according to any one of the preceding illustrative embodiments, wherein the curing agent is selected from polyether diamine or polyether amido or a combination thereof.

9. A curable composition according to any one of the preceding illustrative embodiments, further comprising one or more fillers.

10. A curable composition according to any one of the preceding illustrative embodiments, further comprising one or more inorganic phosphate salts.

11. A substrate containing a coating obtained by curing a composition according to any one of illustrative embodiments 1-10.

12. The substrate according to an illustrative embodiment 11, which is the inner surface of the pipe.

13. The use of alkyl phenol selected from monoalkyl phenols, dialkyl phenols and trialkyl phenols containing an alkyl group selected from unbranched or branched, saturated and olefinically unsaturated C ₁ -C ₈ alkyls to accelerate the curing of the curable epoxy composition.

14. The use of illustrative embodiment 13, wherein the alkyl group is a saturated C ₃ -C ₈ alkyl group.

15. The use of illustrative embodiment 13, wherein the alkyl group is saturated and branched.

16. The use of illustrative embodiment 13, wherein the alkyl phenol is monoalkyl phenol.

17. The use of illustrative embodiment 13, wherein the alkyl phenol is selected from the group consisting of tert-butylphenol, tert-butylphenol, tert-amylphenol, isopropylphenol, and combinations thereof.

18. A method of coating a substrate, in particular, the inner surface of a pipe or pipeline, comprising the steps of:

(i) providing a curable composition in accordance with any of illustrative embodiments 1-10,

(ii) applying a mixture of the first and second parts of the curable composition to a substrate, preferably by spraying, brushing, painting, dipping, spraying, applying with a knife device, applying with a roller, applying with a strip or combinations, and

(iii) providing curing of the curable composition.

Claims (27)

1. Curable multicomponent epoxy coating composition containing an epoxy resin, an amine-containing curing agent and a curing catalyst, where the specified composition contains a curing agent in the first part and an epoxy resin in the second part, separately from the specified first part, where the curing catalyst is an alkyl phenol selected from monoalkyl phenols, dialkyl phenols and trialkyl phenols containing an alkyl group selected from straight or branched chain saturated C ₁ -C ₈ alkyls, and where the amine-containing curing agent is polyetheramidoamine. 2. A curable composition according to claim 1, wherein said alkyl group is a saturated C ₃ -C ₈ alkyl group. 3. Curable composition according to claim 1 or 2, where the specified alkyl group is saturated and branched. 4. Curable composition according to any one of paragraphs. 1-3, wherein said alkyl phenol is monoalkyl phenol. 5. Curable composition according to any one of paragraphs. 1-4, wherein said alkyl phenol is selected from the group consisting of tert-butylphenol, sec-butylphenol, tert-amylphenol, isopropylphenol, and combinations thereof. 6. Curable composition according to any one of paragraphs. 1-5, where the specified epoxy resin is diglycidyl ether, corresponding to the General formula

, where R ⁴ represents a p-valent group, which is aromatic or is a combination of aliphatic and aromatic units, and p is 2. 7. Curable composition according to any one of paragraphs. 1-6, wherein said epoxy resin is diglycidyl ether containing units derived from bisphenol A or bisphenol F, or a combination thereof. 8. Curable composition according to any one of the preceding paragraphs, optionally containing one or more fillers. 9. Curable composition according to any one of the preceding paragraphs, optionally containing one or more inorganic phosphate salts. 10. A substrate containing a coating obtained by curing the composition according to any one of paragraphs. 1-9. 11. The substrate according to p. 10, which represents the inner surface of the pipe. 12. The use of alkyl phenol selected from monoalkyl phenols, dialkyl phenols and trialkyl phenols containing an alkyl group selected from unbranched or branched saturated C ₁ -C ₈ alkyls to accelerate the curing of the curable epoxy composition containing an epoxy resin and an amine-containing curing agent, wherein the amine-containing curing agent is polyetheramidoamine. 13. The use of claim 12, wherein said alkyl group is a saturated C ₃ -C ₈ alkyl group. 14. The use of claim 12, wherein said alkyl group is saturated and branched. 15. The use of claim 12, wherein said alkyl phenol is monoalkyl phenol. 16. The use of claim 12, wherein said alkyl phenol is selected from the group consisting of tert-butylphenol, sec-butylphenol, tert-amylphenol, isopropylphenol, and combinations thereof. 17. A method of obtaining a coating on a surface of a substrate, comprising the steps of: (i) providing a curable composition according to any one of paragraphs. 1-9, (ii) applying a mixture of the first and second parts of the curable composition to the surface of the substrate, and (iii) providing curing of the curable composition. 18. The method according to p. 17, characterized in that the surface of the substrate is the inner surface of a pipe or pipeline. 19. The method according to p. 17 or 18, characterized in that the curable composition is applied to the surface of the substrate by spraying, applying with a brush, staining, applying by immersion, applying by pouring, applying using a knife device, applying using a roller, applying using a bar or a combination thereof.