CZ253297A3 - Composition based on epoxy resin capable of hardening at low temperature and process for preparing thereof - Google Patents

Abstract

An epoxy resin which is a reaction product of a polyepoxy and a polyol which contains both epoxy groups and terminal phenolic hydroxyl groups of at least 0.2 weight percent having added thereto an epoxy novolac having an epoxy functionality greater than two. The epoxy resin is suitable for use as a powder coating exhibiting lower melt viscosity than prior art resins of similar composition. The epoxy resin exhibits higher Tg/softening point than prior art resins of similar viscosity. A powder coating prepared from the resin may be used on temperature sensitive substrates.

Description

The invention relates to epoxy resins capable of curing at low temperature, to a process for the preparation of these epoxy resins and to compositions comprising these epoxy resins.

BACKGROUND OF THE INVENTION

Due to their physical and chemical properties, such as chemical resistance, good adhesion to various substrates, solvent resistance and also good hardness, epoxy resins are useful in a wide range of commercial applications including coating on various substrates, such as on metals and preparation of structural and electrical laminates. In many applications, such as in the coating of inner cans, the epoxy resin is applied as a solution in an organic liquid solvent or as an aqueous dispersion. Powder coatings are also prepared from epoxy resins and can be applied without the use of solvents.

The molecular weight of the epoxy resin generally affects the physical properties of the epoxy resin, such as softening point, melt viscosity and solution viscosity, as well as the physical and chemical properties of the cured product prepared from the epoxy resin.

resin. The higher molecular weight of the epoxy resin then generally results in higher toughness.

High molecular weight resins are products of the reaction of a polyepoxide such as diglycidyl ether of bisphenol A with a polyhydric phenol such as bisphenol A (the so-called cross-linked epoxy resins). This cross-linking reaction between the epoxy group and the hydroxyl group of the phenol forming the β-hydroxyl group results in a chain of molecules widening. Along with this crosslinking reaction, the crosslinking process also takes place.

The epoxy resin crosslinking process is generally a process in which a low molecular weight epoxy resin is first prepared by reacting a polyhydric phenol with epichlorohydrin and an alkali metal hydroxide in the presence of a catalyst to form a polyepoxide. Subsequently, this initial polyepoxide reaction product is amplified by reaction with an additional amount of polyhydric phenol to form a higher molecular weight material by a conventional method used to prepare the epoxy resin. According to conventional processes for the preparation of epoxy resins, the reaction of polyepoxide and polyhydric phenol is generally carried out to achieve complete conversion, the resulting crosslinked epoxy resin containing relatively small amounts of residual phenolic hydroxy groups. For example, an epoxy resin having an EEV (epoxy equivalent weight) value ranging from 500 to 700 and prepared from bisphenol A and bisphenol A diglycidyl ether typically contains less than 800 parts per million. (Ppm) phenolic hydroxyl groups, representing more than 98% conversion of the phenolic hydroxyl groups used in the preparation of this epoxy resin. Typically, an epoxy resin having a higher molecular weight and an EEV of from 2000 to 4000 contains less than 2500 ppm of phenolic hydroxy groups, which represents more than 95% conversion of phenolic hydroxy groups.

It has been found in the prior art that the presence of any amount of residual phenolic hydroxy groups in the crosslinked resin causes the viscosity instability of the resulting resin composition, especially at elevated temperatures. U.S. Pat. No. 3,842,037 proposes adding a strong inorganic acid as a means of controlling the viscosity reduction of the resin due to the presence of unreacted phenolic hydroxy groups when at least 85% of the phenolic hydroxy groups have been converted by reaction, preferably at least 95% of the phenolic hydroxy groups used. in an intensifying reaction.

U.S. Pat. No. 3,352,825 describes another method of preparing a high molecular weight epoxy resin which comprises condensing a dibasic phenol with an excess of epichlorohydrin in the presence of a catalyst such as an alkali metal salt or an inorganic monobasic acid ammonium salt such that an intermediate containing free hydroxyl groups in an amount ranging from 0.2 to 0.5 phenolic hydroxyl groups per mole of the dibasic phenol was formed. Subsequently, this excess epichlorohydrin is removed, and the condensed intermediate is then subjected to a condensation intermediate. · Dehydrohalogenation with an alkali metal hydroxide, and at the same time these free phenolic hydroxy groups are reacted with epoxy groups formed in situ.

However, increasing the molecular weight of the epoxy resin also increases the viscosity of the melt and solution thereof. Increasing the viscosity of the melt and solution then complicates the usefulness of the epoxy resin when applied in powder form as a surface coating. The viscosity represents the creep resistance of the combined powder particles. The surface tension represents the driving force for this creep of the coating. Limited creep may cause a defective orange peel-like appearance on this coating;

P.G. de Lange, Film Formation and Rheology of Powder Coatings, 56 J. Coatings 717, October 1994 pp. 23-33.

One way to reduce the melt and solution viscosity of an epoxy resin having a given EEV is to control the chain growth of the crosslinked resin obtained by preparing a reaction product of a polyepoxide and a polyol, the reaction product comprising both epoxy groups and terminal hydroxyl groups.

In the United States patent no. No. 4,722,981 describes an epoxy resin comprising both epoxy groups and hydroxyl end groups, wherein both the epoxy groups and the hydroxyl end groups are present in an amount of at least 0.25% by weight, the weight percent being are based on the total weight of the reaction product as epoxy resins. This resin can be used as a starting material for the process according to the invention.

The present invention.

Regardless of the benefit that the resin of this U.S. Patent No. 4,722,981 presents to the art, the resin, when used in coating, exhibits characteristics that limit its applicability to substrates capable of withstanding relatively severe conditions curing of the powder coating.

If these powder coatings, as they are known today, are to be economically viable at all, they need to be cured at a temperature in the range of from 160 ° C to 200 ° C. At lower curing temperatures, these powder coatings could also be applied to temperature sensitive substrates such as wood and thermoplastic materials.

Methods of forming solvent-applied coating systems that do not require elevated temperature for curing are also known in the art. These solvent epoxy coating systems can thus be applied to temperature sensitive substrates. These volatile organic solvents required for these solvent-based systems are considered to be harmful to the environment. Powder coatings which are substantially free of volatile constituents and which can be cured on thermally sensitive substrates offer the possibility of reducing solvent leakage to the environment while still allowing the formation of coatings on thermally sensitive substrates.

Existing epoxy-based coating systems may have resins that may be present. be cured at considerably long time intervals at temperatures below 160 ° C so that the bisphenol A-based epoxy resin coating can be cured with a bisphenol A type phenolic curing agent at 120 ° C for a time ranging from 20 to 22 minutes. It has generally been observed in these processes that a lower coating viscosity at the melting temperature leads to better adhesion for otherwise comparable resins (see P.G. de Lange). Lower molecular weight resins and curing agents generally exhibit lower viscosity values than comparable higher molecular weight resins and curing agents.

The problem of inadequate wetting and hence poor adhesion of the coating to the substrate is not only solved by reducing the molecular weight of the resin. In fact, by reducing the molecular weight, adverse effects occur. The reduced molecular weight is also generally correlated with the reduced softening point and lower glass transition temperature of this resin. The reduced softening temperature may result in agglomeration and adhesion of the resin particles to each other during storage, limiting the shelf life of the resulting powder coating material and thereby forming a coating with unsatisfactory smoothness.

Accordingly, there is a need in the art to provide an epoxy powder coating that exhibits low viscosity at low curing temperature and thus allows good wettability of the coating on a temperature sensitive substrate while maintaining a sufficiently high softening / glass transition temperature Tg. · * · · · · · · ···

the constituent (s) of the resin to allow an adequate shelf life. Of course, it is also necessary that quality coatings also meet other requirements, such as good flowability (no appearance of orange peel), good flexibility, high gloss and good corrosion resistance. Also, the use of these coatings for non-temperature sensitive substrates is not excluded since further improvements in properties such as flowability and appearance can be achieved.

SUMMARY OF THE INVENTION

BACKGROUND OF THE INVENTION The present invention relates to epoxy resins useful for forming powder coatings which exhibit low viscosity at low curing temperature, good creep properties and good wettability of the coating material, high-quality gloss, high flexibility and good protective properties. softening temperatures relative to the glass transition temperature T that are sufficient to achieve

About adequate storage times. More particularly, the invention relates to an epoxy resin comprising a reaction product of a polyepoxide and a polyol, the reaction product comprising both epoxy groups and terminal phenolic hydroxyl groups, the amount of both the epoxy groups and the terminal hydroxyl groups being at least 0.2% by weight. wherein the weight percent is based on the total weight of the reaction product as an epoxy resin, with the addition of an epoxidized phenol-formaldehyde resin having a value M _{n of} about 1 n. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

998 9 9

9 9 9

At least 450, an M _w / M _{n value} greater than 1.05 and further having an epoxy functionality greater than 2.

In one embodiment, it is an object of the present invention to provide an epoxy resin comprising a reaction product of a polyepoxide and a polyol, the reaction product comprising both epoxy groups and terminal phenolic hydroxyl groups, the amount of both epoxy groups and hydroxyl terminal groups being at least 0 2% by weight, based on the total weight of the reaction product in the form of an epoxy resin, with an epoxidized phenol-aldehyde resin having an epoxy functionality greater than 2 in a preferred embodiment of the invention.

In another embodiment, the object of the present invention is to provide a process for preparing an epoxy resin composition, the process comprising combining a polyol reactant of the following general formula I under isothermal reaction conditions:

• _{4 t} ··· « _{4 t} ··· · ₄ · in which:

each of A may independently be -S-, -SS-, -C (O) -, -S (O) -, -S (O) ₂ -, a divalent hydrocarbon radical containing from one to eight carbon atoms, or an oxygen, sulfur or nitrogen containing hydrocarbon moiety, optionally representing a covalent bond; this symbol A may further represent residues:

CCl ₂ in which;

each of X may independently represent hydrogen, halogen or an alkyl group containing from one to four carbon atoms, and wherein n has an average value ranging from 0 to 5, preferably from 0 to 2;

or components of formula II:

m ·· ·· · · · · · · · · · · ·

each of R may each be a hydrogen atom or an alkyl group containing from one to four carbon atoms, and wherein each Y may independently represent a hydrogen, chlorine, bromine or lower alkyl group containing from one to four carbon atoms, m it has an average value ranging from 0 to 10, or a mixture of compositions of formula I and formula II with an epoxy reactant of formula III:

O

Ch —ch ₂ -ch-ch ₂ in which:

each of A and X has the same meaning as defined above in relation to formula I above, and wherein n has an average value ranging from 1 to 2; is in the range of 0 to 4;

Or the epoxy reactants of formula IV:

in which :

R and Y have the same meaning as defined above for Formula II;

or polyglycidyl ethers of polyglycols such as diglycidyl ether of polypropylene glycol, or polyglycidyl ethers of tris (phenol) methane or triglycidyl ether of triazine, for example triglycidyl isocyanurate, or such a mixture of epoxy reactants in which the epoxy component and the hydroxyl component are present in a ratio from 0.1: 10 to 10: 1, wherein the reaction progress is inhibited by the reaction catalyst to achieve a predetermined degree of conversion of the reactants, wherein the resin comprises at least about 0.2% by weight of terminal hydroxyl groups and at least about 0 2% by weight of terminal epoxy groups.

The resulting coating composition exhibits a reduced melting viscosity compared to a similar composition not containing an epoxidized phenol-formaldehyde resin. Accordingly, a powder coating can be obtained from this resin composition, which exhibits a more advantageous flowability and hence a higher wettability and a better adhesion.

The epoxy resins of the present invention offer a large number of advantages over commercially available epoxy resins which undergo conversion to such an extent that in a reasonable period of time there is no more significant cross-linking reaction between epoxy end groups and hydroxyl groups. terminal groups (sometimes referred to as totally converted) and which contain substantially no terminal hydroxyl groups. The melt viscosity and solution viscosity values of these new resins are reduced compared to the viscosity values of the prior art fully converted resins of similar composition. In the case of resins having a given melt viscosity at a given temperature, these new resins provide a higher Tg temperature, which correlates significantly with the softening point and hence also with the same melt viscosity at the same temperature compared to the fully converted resins known in the art. longer shelf life.

Due to the fact that these resins contain both epoxy end groups and hydroxyl end groups, these resins can form advantageously useful, homogeneous, one-component systems that do not require post-treatment with the curing agent. Powder coatings can then be formed from these resins by simply adding the accelerator.

The epoxy resin coating composition according to the invention comprises a polyhydric alcohol.

·· ··

containing on average more than one hydroxyl group, preferably 1,8 or more hydroxyl groups per molecule, said hydroxyl groups being capable of reacting with the epoxy groups of the polyepoxide. These polyols may be saturated or unsaturated aliphatic, alicyclic, aromatic or heterocyclic compounds which may be substituted with one or more non-interfering substituents such as halogen atoms or ether groups. Preferred polyols are polyhydric phenols. The polyhydric phenols used in the preferred embodiment for the preparation of epoxy resins are polyhydric phenols represented by the following structural formula I:

in which :

each A independently may represent -S-, -SS-, -C (0) -, -S (0) -, -S (0) 2 ^_ »divalent hydrocarbon radical containing from one to eight carbon atoms, furthermore Oxygen, sulfur or nitrogen containing hydrocarbon residue 99 99 99 9 9 9 9 9 · 999999 9999 9 • 9 9 9 9 ·· · 9 · 99 this symbol may represent a covalent bond or one of the following structural groups:

in which :

each of X may independently be hydrogen, halogen or an alkyl group containing from one to four carbon atoms, and wherein n has an average value ranging from 0 to 5, preferably from 0 to 2; and phenol-aldehyde condensed resins of formula II:

in which :

each of R may each be a hydrogen atom or an alkyl group containing from one to four carbon atoms, and wherein each of Y may independently represent a hydrogen, chlorine, bromine or lower alkyl group containing from one to four carbon atoms, • * * e e e e e e e e e e e e e e e e e e Where the symbol m has an average value ranging from 0 to 10.

Mixtures of one or more of these polyhydric phenols may also be used in a preferred embodiment of the invention.

The polyhydric phenol is preferably a polyhydric phenolic compound represented by the general structural formula I, wherein A is a divalent hydrocarbon radical containing from one to eight carbon atoms, each X being hydrogen and n having an average value ranging from 1 to 8 carbon atoms. from 0 to 0.5, in a particularly preferred embodiment, the value is 0. Among these polyhydric phenols, a particularly preferred embodiment of the invention is used.

2,2-bis (4-hydroxyphenyl) propane, commonly referred to as bisphenol A (BPA).

The initially reacted polyepoxide component used in the preparation of the epoxy resin of the present invention is a compound containing two or more epoxy groups. The polyepoxides may be saturated or unsaturated aliphatic, cycloaliphatic (alicyclic), aromatic or heterocyclic compounds, the polyepoxides being substituted by one or more non-interfering substituents, such as halogen atoms or ether groups, which under conditions such as the resins prepared are not reactive with epoxy or hydroxyl groups. The polyepoxide component that is reacted with the polyol to form a resin may be monomeric or polymeric.

β ·

Illustrative examples of these epoxy resins useful in the practice of the invention can be found in: The Handbook of Epoxy Resins (H. Lee, K. Nevzile, McGraw-Hill, New York, 1967, pp. 4-35-4-56).

The group of polyepoxides useful in a particularly preferred embodiment of the invention includes the polyglycidyl ethers of the bisphenol compounds represented by the general structural formula III:

in which :

each of A and X has the same meaning as defined in the description of the compounds of formula I, and wherein n has an average value of from 0 to 4, preferably from 0 to 2, particularly preferably from 0 to 2; range from 0 to 0.5; the polyglycidyl ethers of novolak resins, i.e. the phenol-aldehyde condensates represented by the general structural formula IV:

• ·

Ο-Cl-b-CH-CH-CH-, o-ch ₂ -ch-ch- ₂

L m

o-ch ₂ -ch-ch-ch ₂ in which:

R, Y and m are as defined above for compounds of formula II;

polyglycidyl ethers of polyglycols such as polypropylene glycol diglycidyl ethers; and polyglycidyl ethers of tris (phenol) methane, or triglycidyl isocyanurate. Mixtures of one or more polyepoxides may also be used in embodiments of the invention. Preferably, the polyepoxides are liquid polyglycidyl polyethers of bisphenol, particularly preferred diglycidyl ether of bisphenol A; polyglycidyl polyethers of tetrabromobisphenol, in particular preferred tetrabromobisphenol A diglycidyl ether, or mixtures thereof may be used.

The polyepoxides and polyols are preferably used in an amount such that the ratio of the number of epoxy equivalents in the polyepoxide to the number of hydroxyl equivalents of the polyol is in the range of 0.1: 1 to 10: 1. and the polyol components used in such a ratio that the ratio of epoxy equivalents to hydroxyl equivalents is in the range of 0.3: 1 to 5: 1, particularly preferably in the range of 0.3: 1 to 2: 1 Relative proportions of these polyepoxide

• · · · · · · · · · · · · · ·

and the polyol components will then depend on a number of different factors, such as the specific characteristics of the polyepoxide and polyol employed and the desired properties of the epoxy resin prepared therefrom.

In preparing the resins of the present invention, the polyol and polyepoxide components are contacted in the presence of a catalyst which, under conditions suitable for forming the desired resin, accelerates the reaction between the hydroxyl groups of the polyol and the epoxy groups of the polyepoxide. Preferably, the reaction is carried out only by these components, i.e. in the absence of solvents or diluents.

Materials capable of catalyzing this reaction are well known in the art and are referred to by reference only. Illustrative of such catalysts are those disclosed in U.S. Patent Nos. 2,633,458, 2,658,855, 3,377,406, 3,694,407, 3,948,855,

389,520, 4,354,015 and 3,477,990 and in The Handbook of Epoxy Rests (H. Lee, K. Nevzile, McGraw-Hill, New York, 1967, pp. 11-13-11-23). Representative examples of these described catalysts are secondary and tertiary amines, preferably tertiary amines such as benzyldimethylamine, triethylamine and benzyldiethylamine; alkali metal hydroxides such as potassium hydroxide; quaternary ammonium compounds of the tetraalkylammonium halide type, such as tetramethylammonium chloride, and phosphines and quaternary phosphonium salts, such as triphenylphosphine and ethyltriphenylphosphonium acetate.

»· · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

This catalyst is generally used in the amounts commonly used. The amounts used vary depending on the specific type of catalyst, the polyepoxide and the polyol used, but are preferably from 0.001% to 1% by weight based on the total weight of the polyol and polyglycidyl ether. folders. In a particularly preferred embodiment, the catalyst is used in an amount ranging from 0.01% to 0.25% by weight, based on the total weight of the polyol and polyglycidyl ether components.

Despite the above-mentioned preferred embodiment, the reaction of the polyol and polyepoxide component can be carried out in the presence of a diluent, but this is not a preferred embodiment of the invention. When used, the diluent is selected in the embodiment of the invention to exhibit dissolution or miscibility with both the polyol and polyepoxide components. Representative solvents that may be used in the present invention include various glycol ethers such as ethylene glycol monomethyl ether or propylene glycol monomethyl ether, and esters thereof such as ethylene glycol monoethyl ether acetate; ketones such as methyl isobutyl ketone, methyl ethyl ketone and acetone; and aromatic hydrocarbons such as toluene, xylene or mixtures thereof. When used, these organic liquid solvents are generally used in an amount of from 5% to 300%, based on the total weight of the polyol and polyglycidyl ether components.

· 99 99 99 99 99 99 99

The reaction of the polyol and the polyepoxide is preferably carried out at an elevated temperature in the range of from 60 ° C to 200 ° C, in particular from 100 ° C to 180 ° C. This reaction is carried out until the desired degree of conversion is achieved as determined by observing measurable parameters such as by measuring the residual content of epoxy or hydroxyl end groups in the resin or by measuring the melt viscosity. The reaction is suitably completed when the desired final conversion step is reached.

A suitable method of predicting the approximate period of time during which the desired resin characteristics will be achieved is to perform this reaction on a laboratory scale under conditions that are substantially isothermal, terminating the reaction after varying lengths of time, and to determine the extent of the reaction using measuring physical or chemical parameters such as melt viscosity and residual hydroxyl group content, these measurements being carried out in a conventional manner known to those skilled in the art.

Any method that effectively prevents the reaction from proceeding further when the desired degree of conversion is achieved can be used in the present invention. This reaction is effectively inhibited when the reaction rate of the hydroxyl and epoxide groups is sufficiently reduced in such a way that the further reaction, when it is in progress, does not significantly or negatively affect the reaction product or its utility characteristics. In a preferred embodiment of the invention, the reaction is sufficiently inhibited such that the viscosity of the reaction is sufficiently high. . . --.-. · · ··· ·

........ · ». ..

the resin remained substantially constant or increased only slightly over time. For example, once the desired degree of conversion has been achieved, the reaction mixture may be quenched to quench the reaction. This rapid cooling of the reaction mixture must, however, be carried out with caution to prevent precipitation of the resin or the formation of lumps and to protect the resin against the formation of large pieces of solid matter which cannot subsequently be used.

A suitable way to cool the reaction mixture is to add a solvent to the reaction mixture, which will dilute the mixture and lower its temperature. The amount of organic solvent added depends on the reaction temperature and the temperature at which the reaction is efficiently terminated. The addition of the organic solvent to the reaction mixture is preferably carried out when the resin is expected to be applied from solution.

The inhibition of this reaction is preferably carried out in a manner in which a material is added to the reaction mixture which effectively inhibits further reactions, for example by causing catalyst deactivation or interrupting the reaction mechanism, thereby inhibiting further reactions between the polyol and the polymer. polyepoxide.

Especially potent inhibitors of this reaction have been found to be strong inorganic and organic acids and anhydrides and esters of these acids (including half esters and partial esters). Under the term strong acid is herein understood an organic acid having a _pKa value less than 4, preferably less than 2.5. As a representative example of these reaction 99 99 9

9 · t

Inhibitors include inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid; inorganic acid anhydrides such as phosphoric anhydride (P2O5); and inorganic acid esters such as dimethyl sulfate; organic acids such as alkyl, aryl and aralkyl acids and substituted alkyl, aryl and aralkylsulfonic acids such as p-toluenesulfonic acid and phenylsulfonic acid and stronger organic carboxylic acids such as trichloroacetic acid and alkyl esters of such acids such as alkyl esters of p-toluenesulfonic acid, for example methyl p-toluenesulfonate and ethyl p-toluenesulfonate, and methanesulfonic acid methyl ester. An example of a strong organic acid anhydride that can be used in the present invention is p-toluenesulfonic anhydride. Preferably, alkyl sulfuric acid esters are selected from these reaction inhibitors; aryl or aralkylsulfonic acids and alkyl esters thereof. In a particularly preferred embodiment of the invention an alkyl ester of para-toluenesulfonic acid such as methyl or ethyl p-toluenesulfonic acid is used as the reaction inhibitor.

The amount of reaction inhibitor added to the reaction mixture is dependent on the specific characteristics of the inhibitor used and the catalyst used in the preparation of the resin. This inhibitor is generally added in an amount sufficient to overcome the catalytic activity of the catalyst. Preferably, at least 0.9 equivalents of inhibitor is added for each equivalent of catalyst used, more preferably at least 2 equivalents of inhibitor per equivalent of catalyst. Despite the fact that the maximum amount of inhibitor added to the reaction mixture is dependent upon the desired properties of the resin and the cost associated with the addition of excess inhibitor, the inhibitor is preferably added in an amount not exceeding 5 equivalents per equivalent of catalyst in the reaction mixture. mixtures.

The resin according to the invention can also be prepared by lowering the temperature of the reactants. Additional temperature control of the reactants can be achieved by carrying out the reaction in an extruder in which temperature controlled zones are provided. The high temperature zone can be used in the embodiment of the invention to heat the reactants to a temperature sufficient to dampen the catalytic activity of any catalyst present. Additionally, an inhibitor may be added to these reactants to interrupt the activity of the catalyst, or another mechanism may be employed to stop the reaction of the reactants. Termination of the reaction by lowering the temperature affords the advantage that the resin does not contain the inhibitor required to rapidly cool the reaction mixture in a batch process with the addition of an inhibitor.

This reaction is complete when the resulting resin contains the desired amounts of epoxy groups and terminal hydroxyl groups. In an embodiment of the present invention, the content of both the epoxy groups and the hydroxyl end groups will be at least 0.2% by weight. The term epoxy group is used herein to refer to a moiety characterized by the term " epoxy group " • · · · I *

999 9 4 • · 1 ·· 99 with the following structural formula:

the residue having an equivalent weight of 43. The term hydroxyl end group refers to a hydroxyl end group having an equivalent weight of 17.

The percentage by weight of epoxy groups in the epoxy resin may be determined as described in U.S. Patent No. 4,722,981.

These percentages by weight may also be expressed as the number of equivalents of these epoxy and hydroxyl groups per kilogram of resin formed. According to the invention, it has been found that the content of 0.2% by weight of epoxy groups corresponds to approximately 0.0465 epoxy equivalents per kilogram of resin produced. Similarly, a content of 0.2% by weight of hydroxyl groups corresponds to about 0.12 hydroxyl equivalents per kilogram of resin produced.

The hydrolyzable chloride content of the resin is generally less than 1% and in many cases less than 0.5%, these percentages being based on the total weight of the epoxy resin formed. In an embodiment of the invention, however, a hydrolyzable chloride content of up to 5% by weight can be tolerated, preferably

♦ «

• · · · · · · · • • ···· · _M * t • ♦ · embodiments and do not exceed 2% by weight of ICI, said percentages sum j based on the total weight of the epoxy resin formed by reacting. In an embodiment of the invention, these amounts of hydrolysable chloride are determined as described in The Handbook of Epoxy Resins, pages 4-29 and 4-30 (Table 4-23).

Despite the fact that the amount of epoxy and hydroxyl end groups contained in the preferred embodiment of the present invention in the resin is dependent upon the desired properties of the resin, such as the viscosity of the solution thereof, the resin preferably contains at least 0.5% by weight. a particularly preferred embodiment of at least 1% by weight of epoxy groups and at least 0.2% by weight of terminal hydroxyl groups. These weight percentages are based on the total weight of the resin. In general, the epoxide content of the resin is less than 20% by weight, preferably less than 12% by weight, while the terminal hydroxyl group content is generally less than 10% by weight, preferably less than 7% by weight.

In the first step of preparing the resin, the conversion of the polyol and polyepoxide components is controlled so that the resin contains the desired amounts of epoxy and hydroxyl groups. This conversion is dependent on the amount of polyol and epoxide used. Preferably, the conversion is carried out so that at least 45% and at most 95% of the deficit reagent is reacted. If the reactants are present in equivalent amounts, then at least it will react.

And not more than 95% of the two reactants. Preferably, the reaction is conducted to react at least 50%, particularly preferably at least 55% and at most 95%, most preferably at most 90%, or no more than 85%, of the deficient reagent or both of the equivalent reactants.

The number average molecular weight of the resin is dependent upon the desired end application of the resin and the physical and chemical characteristics required for that end application. Preferably, the resins have a molecular weight of less than 10,000. More preferably, the resins have a molecular weight of less than 4,000, more preferably less than 2,000, and more preferably greater than 300, most preferably higher than 500.

In the embodiment of the invention, the polyepoxide may be crosslinked with the aid of a polyol, or the crosslinking may be terminated with a polyacid (thereby producing a resin containing either epoxy groups or hydroxyl end groups only, depending on the reactant used in excess). The polyepoxide may be reacted with a polyol or polyepoxide component to form the desired resin. Crosslinking of epoxides with dibasic acids is discussed in Advances I. Polymer Science (P. J. Madec et al., 71 (1985) 153-224) and in Example 18 of U.S. Patent No. 4,722,981.

In the second stage of preparation, which proceeds from the reaction reaction. The product obtained in the first step containing unreacted hydroxyl and epoxy groups is added to this resin a compound having an average functionality of greater than 2. This component causes a decrease in viscosity at curing temperature and The reaction with the reaction product of the first stage of preparation. Thus, this component added in the second stage of preparation may be referred to as a reactive diluent.

Due to the fact that the resin obtained in the first reaction step contains both free hydroxyl end groups and free epoxy end groups, this compound capable of causing crosslinking added in the second stage of preparation may be a compound that is capable of reacting with both hydroxyl and isocyanate groups. epoxy groups.

Compounds capable of reacting with hydroxyl groups and suitable for addition in this second stage of preparation are preferably polyglycidyl ether aldehyde-phenol condensed resin compounds as described above for Formula IV.

For these polyglycidyl ethers, the average value of the parameter m should be in the range of 0 to 5.0, preferably in the range of 0.5 to 4.5. A mixture of polyglycidyl ethers containing polyglycidyl ethers of formula III and formula IV may also be used in the embodiment of the invention, with the values of the parameters m and n being in the indicated ranges. These mixtures comprise at least 5%, preferably at least 12%, in a particularly preferred embodiment at least 99%. . · · · ·

·· ·· • ♦ · «

9 99

998 9 9 • 9 9

99% of the hydroxyl-reactive component added in the second stage of preparation and represented by a compound having an average functionality of greater than 2. The remaining hydroxyl-reactive components added in the second stage of preparation may have an average functionality of 2 or lower but greater than 1,2.

Diluents or solvents may be present in this second stage of preparation. The content of these diluents is preferably less than 50% by weight of the total composition.

Compounds capable of reacting with epoxy groups and suitable for addition in this second stage of preparation are preferably polyhydric phenols described above in connection with formula II. In the case of these polyhydric phenols, the average value of the parameter m should be in the range of 0 to 5.0, preferably in the range of 0.5 to 4.5.

A mixture of polyhydric phenols comprising polyhydric phenols of formula (I) or (II) may also be used in an embodiment of the invention, with the values of m and n being within the ranges indicated. These mixtures comprise at least 10% of the epoxy-reactive component, preferably at least 20%, more preferably at least 25% of the epoxy-reactive component added in the second stage of preparation and represented by a compound having an average higher functional group proportion Diluents or solvents may be present in this second stage of preparation. The content of these diluents is preferably less than 50% by weight, based on the total composition.

»·» »» »» »» »» »» »» »» »» »» »

Certain preferred embodiments of the present invention provide particularly significant advantages, since it is possible to obtain epoxy resins capable of curing at relatively low temperatures, and these epoxy resins exhibit significantly improved utility properties in comparison with the prior art resins, in particular when these epoxy resins are used as coating materials.

Because of the possibility of terminating the reaction after a certain degree of conversion has been achieved, a resin having many different compositions can be prepared in an embodiment of the invention, which can be used in a variety of end applications. For example, the resin may be admixed with an accelerator, and optionally other additives such as a flow control agent to prepare a powder coating composition. The resin may be cured without the addition of a curing agent, although in the embodiment of the invention the curing agent may also be added to the resin component, since the resin contains both unreacted epoxy and unreacted terminal hydroxyl groups.

The curing agents, catalysts and accelerators commonly used in epoxy resin powder coating compositions may be used in the resin coating compositions of the present invention. Such curing agents and accelerators are well known in the art and are referred to herein by reference. Representative examples of accelerators include stannous salts of monocarboxylic acids such as stannous octoate or stannous laurate, various alkali metal salts such as

• 9 · · 9 · ·

For example, lithium benzoate, certain heterocyclic compounds such as imidazole and benzimidazole compounds and salts thereof, onium compounds such as quaternary ammonium compounds, quaternary phosphonium compounds and phosphines of tertiary amines and phenolcarbamates.

Preference is given to the use of accelerators which are solid at room temperature for the preparation of powder compositions, including imidazoles, particularly preferably alkyl-substituted imidazoles, such as e.g.

2-methylimidazole, solid phosphines or amines such as triphenylphosphine, quaternary phosphonium compounds and quaternary ammonium compounds.

The amount of this accelerator used in the preparation of the powder coating compositions of the present invention will vary depending upon the specific characteristics of the accelerator used. Preferably, the accelerator will be used in an amount ranging from 0.01% to 5% by weight based on the weight of the resin. In a particularly preferred embodiment, the accelerator is used in an amount ranging from 0.02% to 3% by weight based on the weight of the resin.

Representative examples of optional curing agents include phenol hardeners such as phenolic or cresol novolaks and phenolic hardeners described in UK Patent No. 1,429,076, dicyandiamide, acid anhydrides such as trimellitic anhydride, polyesters functionalized with by acid and hydrazides such as adipic acid dihydrazide and isophthalic acid dihydrazide. If these are ····

·· ·

9 9

9 99

When the curing agents are used, their amount generally ranges from 1% to 50% by weight based on the total weight of the resin.

It has been found that the number of epoxy group equivalents per kilogram of resin in this second-stage reacted resin useful for the preparation of powder coatings ranges from 1.54 to 2.1. The maximum number of these epoxy equivalents is 5.9. Excess epoxy equivalents cause low softening point values. Preferably, the amount of these epoxy equivalents is greater than 4.1 per kilogram of resin. In a particularly preferred embodiment, the epoxy equivalent content of the resin before the conversion of any of the epoxy groups into the epoxy derivative groups ranges from 5.4 equivalents to 5.9 equivalents per kilogram of epoxy resin. The content of terminal phenolic hydroxy groups in this resin ranges from 0.2 equivalents to 1.5 equivalents per kilogram. Thus, according to the invention, it has not only been found that the above concentration ranges of hydroxyl groups and epoxy groups are required to perform controlled conversion of the resins leading to the formation of epoxy resins suitable for coating materials, but surprisingly it has also been found that groups contained in these resins treated by controlled conversion into epoxy derivative groups such as alpha-glycol groups or phosphate-ester groups, curing times are significantly reduced compared to resins which do not undergo any further conversion of terminal epoxy groups, with good properties of these resins, as well as these resins, as well.

The good properties of these coating materials are retained in the embodiment of the invention.

The epoxy groups contained in this controlled conversion of the treated resin can generally be converted to any epoxy derivative groups that will not adversely affect the curing reaction. Without being limited by theory, it is believed that the hydrolytic reaction of the epoxy group with added water leads to the formation of alpha-glycols, and is not intended to limit the invention in any way. Thus, the addition of water is a method by which, in a preferred embodiment of the invention, epoxy groups can be converted to suitable epoxy derivative groups. The number of equivalents of epoxy groups will then determine the amount of water or other reactants necessary to form the alpha-glycol and optionally other types of epoxy derivative groups. The water is generally used in an excess amount ranging from 0.5% to 20% by weight based on the total weight of the resin, preferably from 1% to 10% by weight.

Reaction of the resins with water and acid can also be used to convert epoxy groups. There is a theory that this reaction converts epoxy groups to alpha-glycols and acid esters and possibly other types of groups derived from epoxy groups, and is not intended to limit the invention in any way. Water and acid are generally used in amounts ranging generally from 0.2% to 10% by weight. These weight percentages are based on the total weight of the resin to which the water and the acid are added. * 9 9 9

9 9 8 9 9 9 9 9 9 9 9 9 According to a preferred embodiment of the invention, the corresponding percentage by weight of water and acid is between 0.5% and 3% by weight and between 0.2% and 2% by weight.

In one embodiment of the invention, the epoxy groups of the controlled converted resin are reacted with water and a phosphorus-containing acid.

In this embodiment, the amounts of water and phosphorus-containing acid (preferably phosphoric acid) are balanced to maximize monoester formation and minimize triester formation. It has been found that when a phosphorus-containing acid is generally used in this manner together with the controlled converted resin, it should be added in amounts ranging from 0.1% to 3% by weight based on the weight of the resin, in preferably from 0.2% to 1.5% by weight, while the water added with this acid should be added in an amount ranging from 0.2% to 10% by weight, preferably from 0.5% to 3% by weight.

In a first step of another embodiment of the invention, certain amounts of water and acid, preferably a phosphorous-containing acid, are used as a reaction inhibitor in the preparation of the controlled converted resins. The amount of added water and acid is excess compared to the amount intended to inhibit the reaction of the polyol and polyepoxide, which excess is then capable of participating in the reaction with the epoxy groups of the controlled converted resin to form epoxy derivative groups. Preferably, the above-described mixture of these groups comprises alpha-glycols and phosphorus-containing acid esters. Thus, when the acid is used in a manner that both inhibits this reaction and participates in the conversion of epoxy groups to epoxy derivative groups, the acid is used in amounts ranging from 0.1% to 3% by weight based on the weight % resin, preferably from 0.2% to 1.5% by weight.

It can be observed that by converting at least 30% of the epoxy groups of this resin into epoxy derivative groups, the curing rate can be increased and the total curing time can be shortened. Preferably, more than 50% of the epoxy groups are converted to epoxy derivative groups, and in a particularly preferred embodiment substantially all of the epoxy groups are converted to epoxy derivative groups. Despite the fact that they contain essentially no epoxy groups, these resins are understood herein to be epoxy resins, due to their mode of formation. Of course, if this reaction is inhibited and the epoxy groups are converted in a single step and / or with a single reactant, such as phosphoric acid, then it is not necessary to obtain an isolated controlled converted resin having a specific epoxy group content. The limited number of epoxy groups remaining in the resulting resin (if any epoxy groups remain) and the presence of epoxy derivative groups will, in accordance with the purpose of the present invention, indicate in practice the particular mode of carrying out the present invention and more advantageous characteristics.

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Ftft ftft ftft ftft

Alternatively, after the resin has been prepared, the resin thus obtained may optionally be dissolved in an organic liquid for further use.

Suitable organic liquids useful for preparing organic liquid solutions of the resin are selected depending on the specific characteristics of the resin and the amount of terminal hydroxyl and epoxy groups in the resin. In general, alcohols such as n-butanol, glycol ethers such as propylene glycol monomethyl ether and esters thereof, ketones, aliphatic or aromatic hydrocarbons such as xylene and chlorinated aliphatic and aromatic hydrocarbons are preferred for this purpose. hydrocarbons.

In preparing the organic liquid solution of this resin, it is generally desirable to use curing agents which are also soluble in the organic liquid. Such curing agents are well known in the art and are referred to herein by reference only. Representative curing agents include phenolic resins such as the reaction product of phenol with an excess of formaldehyde and other benzene derivatives containing a hydroxymethyl group and alkylated derivatives of these amino-aldehyde condensates commonly referred to as aminoplasts, which are condensed products of the aldehyde-amine reaction, such as melamine, urea and benzoguanamine, and alkylated derivatives thereof.

The amount of the curing agent used in the preferred embodiment of the invention is dependent upon a number of factors including the final application of this organic curing agent. · Liquid solution and desired physical and chemical properties related to this final application. The amount of the curing agent used in the preferred embodiment of the invention is in the range of 1% to 50% by weight based on the total weight of the resin and the curing agent.

In addition, in an embodiment of the invention, it is often desirable to add a small amount of inorganic acid to the organic liquid solution, the inorganic acid acting as a catalyst for the reaction of the resin with the curing agent. The inorganic acid is preferably phosphoric acid which is used in an amount ranging from 0.1% to 5% by weight based on the total weight of the organic liquid solution.

The concentration of solids in the preparation of this organic liquid solution is dependent on various factors including the desired viscosity of the resulting solution. This organic liquid solution is generally prepared in such a way that the solids content is as high as possible while maintaining a sufficiently low viscosity for efficient application. Due to the fact that this resin exhibits a lower solution viscosity than conventional resins which exhibit equivalent curing properties, this organic liquid solution can generally be prepared at higher solids concentrations than the prior art organic liquid solutions containing conventional resins. techniques. For example, the resin usable for the coating materials may be formulated as an organic liquid solution containing at least 40% of the resin and any curing agent, wherein the the percentage is based on the total weight of the organic liquid solution. Preferably, the liquid solution comprises at least 50% resin and curing agent, more preferably the content of resin and curing agent is between 50% and 70% by weight.

Resin powder compositions of the present invention exhibit more advantageous characteristics compared to the prior art, which makes it particularly advantageous to use these resins as coating materials. These coatings preferably have a uniform appearance when applied to the substrate (see P. G. de Lange).

The powder compositions prepared with the resins of the invention preferably also exhibit low viscosity values under curing conditions. In a particularly preferred embodiment of the invention, a particularly low viscosity value can then be achieved due to the addition of the epoxidized phenol-formaldehyde resin to the reactant from the first preparation stage.

The curing of this epoxy resin depends on the temperature and the curing time. The resin of the present invention is capable of curing at a lower temperature than those known in the art. The curing of the resin according to the invention takes place in a shorter period of time than the curing of resins of similar composition known in the prior art. In addition, the cured coating compositions prepared from the resins of the present invention, despite milder curing conditions, exhibit coating characteristics that are comparable to those of the present invention. 9 with 9 compositions known in the prior art. Resins which are capable of curing under similar conditions to those of the inventive embodiment are known in the art. At the same time, however, these resins exhibit a higher Tg / softening point value and thus a longer service life.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing and other advantages of the low temperature curing compositions of the present invention capable of curing at low temperatures and the process for producing them will now be described in more detail by way of specific examples, which are illustrative only and not limiting.

He did

In this example, 2760 parts by weight of bisphenol A diglycidyl ether were combined with 1310 parts of bisphenol A under nitrogen atmosphere in the presence of 1.4 parts of ethyltriphenylphosphonium acetate. The combination was heated to 120 ° C, then the temperature was gradually raised to 150 ° C and held at 150 ° C for a period of time ranging from 1 to 5 hours until it was reached. the desired viscosity measured at a temperature of 120 ° C ranging from 1 to 6 Pa.s.

Upon reaching the desired viscosity, 1 part of 4-toluenesulfonic acid methyl ester was added, and the combination was then stirred for 20-30 minutes. If necessary, it was possible to add a creep-affecting pigment at this point in the preparation, 9 99. • 99 99 · · · · · · · · · · · · · · 99 · · · · · · · · · · · · · · · A buffering agent or other components. Thereafter, 930 parts of an epoxidized phenol-formaldehyde resin having an M _n = 534 and a ratio of Μ ../ Μ _π = 1.7 (5.2 equivalents) preheated to 90 ° C were added thereto, followed by stirring. for a period of time ranging from 10 minutes to 20 minutes.

The reactor contents were then cooled. At room temperature, this resin was in a solid state. The following characteristics were obtained for the resin thus prepared: epoxy equivalent weight 450, softening point 77.6 ° C, melt viscosity at 120 ° C was 2.5 Pa.s, at 150 ° C was 0.4 Pa.s, number average the molecular weight (M _n ) was 900, the weight average molecular weight (M _w ) was 2340 and the ratio of these molecular weights (M _w / M _n ) was 2.6.

Examples 2 to 9

In Examples 2 to 9, the steps of Example 1 were repeated using the reagents listed in Table I. In the procedure of Example 9, the extruder described in Examples 20 to 24 was used. are given in the table below.

Example 10 (not within the scope of the present invention)

In this example, 67.9 parts by weight of bisphenol A diglycidyl ether and 32.1 parts of bisphenol A were combined in the presence of 0.05 parts of ethyltriphenylphosphonium acetate. This composition was

9 9 9 9 9 9 9 9 9

9 9 9999

9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 until the reaction was continued under adiabatic conditions for three hours until it was assumed that this bisphenol A was completely reacted. .

During the adiabatic reaction, the reaction mixture was heated to 190 ° C. An epoxidized phenol-formaldehyde resin having an epoxy functionality of 3.6, an M _{n of} 534 and an M _w / M _{n of} 1.7 was then added to the liquid mixture and added in an amount such that a composition having an epoxidized phenol-formaldehyde resin content according to Table II was obtained. The composition was then allowed to cool to room temperature. The characteristics of this composition are shown in Table II.

Example 11

22.36 parts of bisphenol A diglycidyl ether, 10.33 parts of bisphenol A were charged to the reaction vessel under a nitrogen atmosphere, and ethyltriphenylphosphonium acetate catalyst (207 ppm) was added. The reactants were then heated to 120 ° C with continuous stirring. The mixture was periodically sampled to measure the viscosity of the composition used to determine the extent of the reaction. Based on the viscosity measurements of these samples, it was assumed that a predetermined target viscosity should be reached after approximately 6 hours. The reaction was quenched by the addition of 0.008 parts of p-toluenesulfonic acid methyl ester under continuous stirring. This stirring was carried out for 10 minutes. 7.5 parts of epoxidized phenol-formaldehyde resin having a M _n = 534 and a M _w / M _n = 1.7 ratio were then added to the reaction vessel, and the resin was preheated to 100 ° C. Mon 9 · 9 · 9 • 9 • 9 • 9 9 * 9

This composition was removed for testing for three hours. The resin characteristics determined by this testing are shown in Table II.

• · • •• 4 · · ·

9 • ·· a

TABLE I

Parts by weight 2 * 3 4 5 * A solid epoxy resin containing 40% by weight of an epoxidized phenol-formaldehyde resin having an epoxy content of 3.6, M _n = 534, M _w / M = 1.7. The composition exhibits an epoxy equivalent weight of 325. 22nd The resin of Example 1 without epoxidized phenol-formaldehyde resin having M _n = 534, M _w / M _n = 1.7 Solid epoxy resin EEV = 700-750 Solid Bis A epoxy resin of 4-type with 18.6% epoxidized phenol-formaldehyde resin showing epoxy groups of 3.6, M _n = 534, M _w / M _n = 1.7. 50.3 Solid Bisphenol A-reinforced epoxy resin with epoxy equivalent weight 495-526 25.4 Saturated carboxylated polyester resin. The resin of Example 1 53.4 53.3 Bisphenol A diglycidyl ether, EEV = 180.4, M _n = 422, M _w / M _n = 1.1. Phenolic-type rigid hardener with a hydroxy-equivalent weight of 240 - 270. 15.8 21.7 17.9 16.8 MODAFLOV ^ ² ) 0.4 0.4 0.5 0.45 Flow-Affecting Agent (ResiFlow PV5)

· • «·

TABLE

I (continued) 9 9 9

9

9999 9 9 9 ··· ·

Parts by weight 6 * 7 8 9 A solid epoxy resin containing 40% by weight of an epoxidized phenol-formaldehyde resin having an epoxy content of 3.6, M _n = 534, M _w / M = 1.7. The composition exhibits an epoxy equivalent weight of 325. Resin according to Example 1 without epoxidized phenol-formaldehyde resin having M _n = 534, M _V / ^M n = 1-7 44.0 Solid epoxy resin EEV = 700-750 39.0 Solid Bis A epoxy resin of 4-type with 18.6% epoxidized phenol-formaldehyde resin showing epoxy groups of 3.6, M _n = 534, M _v / M _n = 1.7. Solid Bisphenol A-reinforced epoxy resin with epoxy equivalent weight 495-526 Saturated carboxylated. . polyester resin. '·' 37.0 26.0 31.0 The resin of Example 1 33.0 Bisphenol A diglycidyl ether, EEV = 180.4, M _n = 422, M _w / M _n = 1.1. 50.3 Phenolic-type rigid hardener with a hydroxy-equivalent weight of 240 - 270. 18.7 MODAFLOV ^ ² ) 0.5 Flow Influencing Agent (ResiFlow PV5) (3) 1.0 1.0 1.0

TABLE (continued) 9 9 9 9 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 · · · · · · · · · · · · · · · · It · ·

Parts by weight 2 * 3 4 5 * 1,3-phenoxy-2-propanol 98% methyl-isobutyl ketone 2% TiO ₂ (Kronos 2310) ⁽⁴⁾ 25.0 25.0 25.0 25.0 BaS0 ₃ ( ^? ) 5.0 5.0 5.0 5.0 2-methylimidazole 0.45 0.45 0.45 0.45 Observation 45 (1) 45 1 49 (35) 2 47 (43) (D Gel time at 180 ° C in sec. (after 42 days of storage) Creep (expressed on a scale of 1 to 4; l = quality coating 4 = orange peel appearance) Impact toughness (8) cmkg Front / Rear, steel panel (5) 184 / 184 184 / 184 184 / 184 (5) 115 / 34.5 184/5 7.5 184/5 7.5 (5) 34,5 / 34.5 184 / 161 (5) 34,5 / 34.5 184 / 184 curing temperature 110 ° C 115 ° C 120 [deg.] C Hardness Injection Test (^) (5) 8.8 8.3 8.2 (5) 8.6 8.2 8.6 (5) 0.5 8.7 (5) 0.5 8.5 mm. steel nanelv ^^ a ^ ⁰ / curing temperature 110 ° C 115 ° C 120 [deg.] C 140 [deg.] C - 5 minutes - 20 minutes - 22.5 minutes

TABLE

I (continued) 9 9999 9 9 9 9 9999 9 9999 9 9999 9 9999 9

9 9 9 9 9

9 99 99 99 99 99

Parts by weight 6 * 7 8 9 1,3-phenoxy-2-propanol 98% methyl-isobutyl ketone 2% 1.0 1.0 1.0 Ti0 ₂ ( ⁴ ) 28.0 28.0 28.0 25 BaSO ₄ ( ^? ) 5.0 2-methylimidazole 0.54 Observation Gel time at 180 ° C in sec. (after 42 days of storage) Creep (expressed on a scale of 1 to 4; l = quality coating 4 = orange peel appearance) 107 293 190 35 Impact toughness (8) cm „to Front / Rear steel panel ³ 15min 184 / 184 curing temperature 110 ° C 115 ° C 120 [deg.] C Hardness Injection Test, (6) 7.4 7.5 7,4 (6) 0.5 0.5 0.5 (6) 0.5 1.0 7.4 mm, Danel steel ^ and ^ ⁰ - curing temperature 110 ° C 115 ° C 120 ° C 140 ° C - 5 minutes - 20 minutes - 22.5 minutes

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Examples of the present invention (1) Uralac P 2980 supplied by DSM Kunstharze GmbH, Am Kreisforst 1, D-49716, Meppen, Germany (2) MODAFLO polyacrylate modifier creep supplied by Monsanto Europe SA, Brussels, Belgium (3) ResiFlow PV5 polyacrylate creep modifier supplied by Vorlée Chem, Lauenburg / Elbe, Germany (4) KRONOS 2310. Titanium dioxide supplied by Kronos Titan GmbH, Leverkusen, Germany (5) DIN steel 1624-ST4, degreased, 1 mm thick (6) Bonder ^ 1041600C, chromate treated, used pure, 1 mm thick, supplied by Chemetall, Frankfurt / Main, Germany (7) EVO, Sachleben Chemie, Duisburg, Germany (8) ) ASTM 614, cure time 20 minutes unless otherwise indicated (9) DIN 53156 , curing time of 20 minutes, unless otherwise indicated · * · · · · · · · · · · ·

TABLE II 9999 9999 9

9 9

9

99

9 9

99

998 9 9

9 9

99

Example 10 (parts by weight) Example 11 * (parts by weight) Bisphenol diglycidyl ether 67.9 22.36 Bisphenol A 32.1 10.33 Ethyltriphenylphosphonium acetate 0.05 0.0207 Methyl p-toluenesulfonate - 0,008 part Epoxy equivalent mass 520 438 wt. % epoxide 8.25 9,82 Molecular weight (M _n ) 1398 925 Molecular weight (M _w ) 4331 2000 Μ ^Μ η 3.1 2.2 The epoxidized phenol-formaldehyde resin having an epoxy group of 3.6, M _n = 534, M _w / M _n = 1.7. 22.9 (18.6%) 7.5 (18.7%)

99 ♦ · · · · · · · ·

9 9

Examples 12 to 17

In the embodiments of Examples 12 to 17, the properties of epoxy resin compositions having the same ratio of epoxy groups to phenol groups in the starting material were compared. All compositions were mixed in a Mixaco mixer and then melt extruded at 63 ° C in a Verner & Pfleiderer ZSK30 extruder. Following extrusion and quenching, the solid resin was ground to a practicable grain size, which ranged from 1 to 100 microns for all samples, with an average particle size distribution ranging from 25 to 40 microns.

Table III shows the compositions and properties of the coatings for the embodiments of Examples 11-16.

Example 18

A mixture of 584 parts of bisphenol A diglycidyl ether (EEV 178, 3.28 equivalents) was mixed with 316 parts of bisphenol A (2.77 equivalents) and heated to 95 ° C under stirring and nitrogen atmosphere. Then 0.21 parts of a solution of ethyltriphenylphosphonium acetate, which acted as a catalyst / initiator of the cross-linking reaction, was added. Subsequently, the temperature was carefully raised to 125 ° C and this temperature was then maintained until the melt viscosity of the resin (measured at 120 ° C with a ICI cone-plate viscometer) reached 5 Pa.s. Methyl p-toluenesulfonate (0.8 part) was then added, followed by the addition of 100 parts of epoxidized epoxide. 9 9 9

9 999 • 9999 9

9 9

99 phenol-formaldehyde resins having an epoxy functionality of 3.6, M _n = 534 and M _w / M _n = 1.7. An epoxy resin having a percentage by weight of epoxy groups of from 5% to 12%, an epoxy equivalent weight of from 350 to 900, a Mettler softening temperature of from 70 ° was obtained C to 100 ° C, melt viscosity at 150 ° C was less than 1.0 Pa.s, at 120 ° C ranged from 1 Pa.s to 5 Pa.s and at 100 ° C ranged from 5 Pa.s to 40 Pa.s, number average molecular weight (M _n ) ranged from 750 to 1500, polydispersity ranged from 1.25 to 5.0 and glass transition temperature (Tg) was higher The resin was curable as a coating at temperatures ranging from 90 ° C to 180 ° C and at curing times ranging from 30 minutes to 10 minutes.

Example 19

A resin was prepared in a similar manner to Example 17 except that 484 parts of bisphenol A diglycidyl ether was used together with 200 parts of epoxidized phenol-formaldehyde resin having an epoxy functionality of 3.6, a M _n = 534 and a ratio M _w / M _n = 1.7. The other amounts and conditions are the same as in Example 1.

· «· · · ·

TABLE III

12 13 14 COMPONENTS OF THE FIRST INSTANCE Bisphenol A Bisphenol diglycidyl ether 11.93 37.80 17.80 39.63 14.3 38.75 COMPONENTS OF THE SECOND DEGREE T (° C) second stage resin. O 29.3 54.0 46.1 COMPOSITIONS FOR COATING COATING INCLUDING A CURING AGENT A solid phenolic type curing agent having a hydroxy equivalent weight 240-270 19.82 12.14 16.47 2-methylimidazole 0.45 0.45 0.45 TiO ₂ (Kronos 2310) 29 29 29 MODAFLOV ™ 111 1 1 1 Total weight parts 100 ALIGN! 99.72 100 ALIGN! Gel time at 180 ° C in sec. 63.5 69.0 67.5 COATING CHARACTERISTICS Coating thickness (pm) / Flow rate (· ² '110 ° C) Curing temperature 115 ° C (25 minutes) 120 ° C 73 / 4.6 86 / 4.6 88 / 4.1 77 / 1.9 89 / 1.7 80 / 1.8 75 / 2.1 69 / 2.0 73 / 2.7 Impact test (cm.kg) p = compliant, f = compliant 110 ° C front / rear 115 ° C Curing temperature 120 ° C for 25 minutes f23 / f23 p57,5 / f23 pl84 / pl84 f23 / f23 pl84 / pl84 pl84 / pl84 f23 / f23 pl84 / pl84 pl84 / pl84 Hardness Injection Test (mm) Mp 110 ° C Curing temperature 115 ° C for 25 minutes 120 ° C 0.5 9.5 9.5 0.5 10.0 10.0 9.5 10.0 10.0

99 • 9 9 9 9 9

9 9 9 9 • 9 9 9 9

9

9999 99 • · ···· 9

9 99 • · · ·

9 99

998 9 9

9 9 9

9

TABLE

III (continued)

15 Dec 16 * 17 COMPONENTS OF THE FIRST INSTANCE Bisphenol A Bisphenol diglycidyl ether 13.33 28.39 13.33 28.39 11.90 37.72 COMPONENTS OF THE SECOND DEGREE 9.5 9.5 T (° C) second stage resin. O 46.0 34.0 - COMPOSITIONS FOR COATING COATING INCLUDING A CURING REAGENT A phenolic-type solid curing agent having a hydroxylqualent mass 240-270 18.30 18.18 19.77 2-methylimidazole 0.45 0.45 0.6 Kronos 2310 29 29 29 MODAFLOV ™ 111 1 1 1 Total weight parts 99.97 99.85 99.84 Gel time at 180 ° C in sec. 47.5 45.0 52.0 COATING CHARACTERISTICS ( ¹ ) Coating thickness (pm) / Flow rate ^ ² - '110 ° C Curing temperature 115 ° C (25 minutes) 120 ° C 83 / 2.3 87 / 2.3 80 / 1.7 63 / 2.7 72 / 3.8 76 / 4.3 87 / 4.2 96 / 4.7 92 / 4.9 Impact test (cm.kg) p = compliant, f = not compliant 110 ⁰ C front / rear 115 ° C Cure temperature 120 ° C for 25 minutes f23 / f23 p57,5 / f23 pl84 / pl84 f23 / f23 pl84 / pl84 pl84 / pl84 f23 / f23 pl84 / pl84 pl84 / pl84 Hardness Injection Test (mm) Mp 110 ° C Curing temperature 115 ° C for 25 minutes 120 ° C 2.3 9.5 9.5 1.0 9.4 9.3 8.2 8.5 9.5

9 9 9 9

9

9999 98 9

• · ···· (1) Steel DIN 1624-ST4, degreased, 1 mm thick (2) The determination of the creep degree was carried out using a Byk-Gardener wave-scan device in accordance with the operating manual (1992). Byk-Gardner Gmbh, D-82538 Geretsried Germany. Grades are determined within the range of 0 (poor quality) to 10 (excellent quality).

(3) An epoxidized phenol-formaldehyde resin having an epoxy functionality of 3,6 and an M _n = 534

Examples 20 to 24

In the embodiment of these examples, a reactive mixing extruder of the ZSK-30 type was provided with two co-rotating worms operating at a speed of 100 rpm. The length of the cylinder including the mold was 1410 mm. The cylinder consisted of eleven individual 90 mm long sections and two double 180 mm long sections, and was further provided with a 30 mm long support plate and a 30 mm long end plate. This cylinder comprised an inlet section that was followed by a fixed section, a gas removal section, and the remainder of the cylinder was then alternately formed of passage and fixed sections. A pressure sensor, a safety diaphragm and a pipe connection were placed in the head of this extruder. In the arrangement of this screw, four large mixing sections were included that extended into the extruder head. This cylinder was divided into nine heating and cooling zones. The ninth zone was the extruder head. The epoxy resin was prepared from the starting materials at the entry rates shown in Table IV. Zones 1-3 were operated at 175 ° C, zone 4 at 220 ° C, zones 5 and 6 at 240 ° C and zones 7-9 at 175 ° C.

• ♦ • · «« «« «« «« «« «« «« «« • »» · · · • • • •

TABLE IV

Examples 20 May 21 22 * Bisphenol A diglycidilether having an EEV = 180.4, M _n = 422, M _w / M _n = 1.1 5,05 kg / h 5.1 kg / h 5.1 kg / h Epoxidized phenol-formaldehyde resin showing epoxy groups 3,6, M _n = 534, M _v / M _n = 1,7, EEV = 177 1.7 kg / h Bisphenol A 2.3kg / h 2.3kg / h 2.3kg / h Ethyltriphenylphosphonium acetate 300ppm 300ppm 300ppm Properties of second stage resin Epoxy eq. Phenol eq. mass 661 10800 661 9139 440 7217 Molecular weight M _n ^M w ON. ON. ON.

• · ·

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

TABLE IV (continued)

Examples 23 * 24 * Bisphenol A diglycidilether having an EEV = 180.4, M _n = 422, M _w / M _n = 1.1 5.1 kg / h 5.1 kg / h Epoxidized phenol-formaldehyde resin showing epoxy groups 3,6, M _n = 534, M _w / M _n = 1,7, EEV = 177 1.7 kg / h 1.7 kg / h Bisphenol A 2.3kg / h 2.3kg / h Ethyltriphenylphosphonium acetate 300ppm 300ppm Properties of second stage resin Epoxy eq. mass 442. 6704 441 7321 Molecular weight M _n Mv ON. 693 1914

* Examples of the present invention • • • • • • • • • • • • • • • • • • • • • • ······· ··· ··· · · · «fis *. hm inSreto feivekáí

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PATENT CLAIMS

Claims (19)

CLAIMS 1. An epoxy resin comprising a reaction product of a polyepoxide and a polyol, the reaction product comprising both epoxy groups and terminal phenolic hydroxyl groups in amounts of at least about 0.2% by weight of each of these epoxy groups and terminal phenolic hydroxy groups. the weight percent is based on the total weight of the epoxy resin reaction product, with an epoxidized phenol-aldehyde resin having an epoxy functionality greater than 2 being added to the epoxy resin. Epoxy resin according to claim 1, characterized in that the polyol reactant corresponds to the general formula I: in which : each of the symbols A can independently represent a group • * • 4 ·· -S-, -SS-, -C (O) -, -S (O) -, -S (O) ₂ -, a divalent hydrocarbon radical containing from one to eight carbon atoms, a hydrocarbon radical containing oxygen, sulfur or nitrogen, optionally, it may be a covalent bond; and A may also represent: in which : each of X may independently be hydrogen, halogen or an alkyl group containing from one to four carbon atoms, and wherein n has an average value ranging from 0 to 5, preferably from 0 to 2; or formula II: in which : each of hydrogen or R may individually represent an alkyl radical containing from one to four; • Atomic carbon atoms, and where each of the symbols Y may independently be hydrogen, chlorine, bromine or a lower alkyl group containing from one to four carbon atoms, m having an average value ranging from 0 to 10, or mixtures of the compositions of formula I and formula II with an epoxy reactant of formula III: in which : each of A and X has the same meaning as defined in the above general formula I, and wherein n has an average value ranging from 0 to 4; or formula IV: 9 9 9 9 9 9 ·· ♦ in which: R and Y have the same meaning as defined above for Formula II; or polyglycidyl ethers of polyglycols, such as diglycidyl ether of polypropylene glycol or polyglycidyl ethers of tris (phenol) methane or triglycidyl ether of triazine, for example triglycidyl isocyanurate, or mixtures of epoxy reactants in which the epoxy component and the hydroxyl component are present in a ratio of 0.1 Wherein the reaction progress is inhibited by the reaction catalyst to achieve a predetermined degree of conversion of the reactants, wherein the resin comprises at least about 0.2% by weight of terminal hydroxyl groups and at least about 0.2% by weight of terminal hydroxyl groups. epoxy groups. Epoxy resin according to claim 2, characterized in that for the components represented by the general formula (I), the average value of the parameter n ranges from 0 to 2. Epoxy resin according to claim 2, characterized in that, for the components represented by the general formula (II), the average value of the parameter m ranges from 0 to 4.5. Epoxy resin according to claim 2, characterized in that for the components represented by the general formula (III), the average value of the parameter n ranges from 0 to 2. Epoxy resin according to claim 2, characterized in that for the reactants / components represented by the general formula IV, the average value of the parameter m ranges from 0.5 to 4.5. · »» * * * * * * * . 9 99999 9 9 9 • • » 7. A process for preparing an epoxy resin composition comprising isothermally combining a polyol reactant corresponding to formula I wherein: each of A may independently be -S-, -SS-, -C (O) -, -S (O) -, -S (O) ₂ -, a divalent hydrocarbon group containing from one to eight carbon atoms, hydrocarbon an oxygen, sulfur or nitrogen-containing residue, or this symbol may represent a covalent bond or one of the following structural moieties in which: each of X may independently be hydrogen, halogen or an alkyl group containing from one to four carbon atoms, and wherein n has an average value ranging from 0 to 5, preferably from 0 to 2; »Or components of formula II: in which : each of R may be hydrogen or an alkyl radical of from one to four carbon atoms, and wherein each of Y may independently be hydrogen, chlorine, bromine or a lower alkyl group of from one to four carbon atoms, m it has an average value ranging from 0 to 10, or a mixture of compositions of formula I and formula II with an epoxy reactant of formula III: 4 * 4 4 4 4 · 4 · 4 4 4 4 4 4 4 «4 44 in which: each of A and X has the same meaning as defined in relation to Formula I, and wherein n has an average value ranging from 0 to 4; or components of formula IV: m <»in which: R and Y have the same meaning as defined above for Formula II; or polyglycidyl ethers of polyglycols such as diglycidyl ether of polypropylene glycol or polyglycidyl ethers of tris (phenol) methane or triglycidyl ether of triazines, for example triglycidyl isocyanurate or mixtures of epoxy reactants, in which the epoxy component and the hydroxyl component are present in a ratio of: 10 to 10: 1, wherein the progress of the reaction is inhibited by the reaction catalyst to achieve a predetermined degree of conversion of the reactants, wherein the resin comprises at least about 0.2% by weight of terminal hydroxyl groups and at least about 0.2% by weight of terminal epoxy groups. Method according to claim 7, characterized in that for the components represented by the general formula (I), the average value of the parameter n ranges from 0 to 2. Method according to claim 7, characterized in that, for the components represented by the general formula (II), the average value of the parameter m ranges from 0.5 to 4.5. Method according to claim 7, characterized in that, for the components represented by the general formula (III), the average value of the parameter n ranges from 0 to 2. Method according to claim 7, characterized in that for the components represented by the general formula (IV), the average value of the parameter m ranges from 0.5 to 4.5. 12. The process of claim 7 wherein the molar ratio of epoxy component to phenolic hydroxy component is in the range of 0.3: 1 to 5: 1. 13. The process of claim 7 wherein the reaction of said hydroxyl component and said epoxy component is catalyzed by secondary and tertiary amines selected from the group consisting of benzyldimethylamine, 99 · 9 • 9 9 9 9 99 9 9 9 9 9 9 9 9 9 9 9 • 99999 9 9999 9 9 9 9 9 9 99 9 9 · 99 triethylamine and / or benzyldiethylamine; alkali metal hydroxides such as potassium hydroxide; quaternary ammonium compounds of the tetraalkylammonium halide type, such as tetramethylammonium chloride, and / or phosphines and / or quaternary phosphonium salts, such as triphenylphosphine and / or ethyltriphenylphosphonium acetate. 14. The process of claim 7 wherein the reaction mixture is maintained under isothermal conditions. The method of claim 7, wherein the epoxy-hydroxyl reaction is inhibited by the addition of a strong acid, a strong acid anhydride or a strong acid ester. The method of claim 7, wherein the strong acid, anhydride or ester is phosphoric acid, phosphoric anhydride, dimethylsulfonate, alkyl and arylsulfonic acids such as p-toluenesulfonic acid, trichloroacetic acid; methyl p-toluenesulfonate, ethyl p-toluenesulfonate, and methanesulfonic acid methyl ester. 17. The process of claim 7, wherein the epoxy-hydroxyl reaction is thermally inhibited by means of an extruder by raising the temperature to a level sufficient to decompose the reaction catalyst or by sufficiently quenching the reactants to stop the ongoing reaction. 18. A thermosetting epoxy resin coating material, characterized in that it is formed by curing performed at temperatures ranging from 4 to 44. In the range of 90 ° C to 180 ° C in the range of thirty to ten minutes, the coating material when applied to steel panels has an impact strength of more than 115 cm.kg in the frontal direction , greater than 34.5 cm.kg in the reverse direction, an Erichsen indentation test value greater than 6 mm, and a creep rate determined by a Byk type device greater than 2 using steel panels. 19. The cured epoxy resin coating material of claim 18 wherein said curing is carried out at temperatures ranging from 90 ° C to 120 ° C and at intervals of 30 minutes to 10 minutes.