CH396034A - Process for the preparation of glycidyl derivatives of amino-phenols - Google Patents

Description

Process for the preparation of glycidyl derivatives of amino-phenols

The present invention relates to glycidyl derivatives of amino-phenols in which the amino groups are primary groups. More particularly, the present invention relates to monomeric polyglycidyl amino phenols, in which substantially all the hydrogens of the hydroxyl groups, and substantially all the hydrogens, rean plaargable of the amino groups present in the amino phenols, are replace. by glycidyl radicals. These compounds are useful in the preparation of epoxy resin compositions to be cured, and particularly in the preparation of epoxy resins whose heat deformation occurs at an elevated temperature. Epoxy compositions of this type find use in the manufacture of epoxy resin tools, and the production of abrasive grinds.

Glycidyl derivatives of various phenols and amines have been mentioned in the literature. These derivatives have generally been prepared by reacting a phenol or an amine, respectively, with a suitable alpha-halogen epoxide, such as an 6-pichlorhydrin, in the presence of a suitable catalyst, for example a base. tolle .quo sodium hydroxide. However, this process is generally characterized by the formation of undesirable polymeric products, and low yields of monomeric glycidyl derivatives which are desired.

The present invention provides a process for the preparation of glycidyl derivatives of. amino pihenols, with high yields and without the formation of a predominant proportion of polymeric products.

The owner has found that Fon can prepare glycidyl derivatives of amino-phenols in which each hydrogen atom: of each phenohque group and of each primary amino group is replaced by a glycidyl radical, i.e. i.e. compounds such as the triglycidyl derivative of para-amino-phenol

by reacting a suitable amino, phenol, for example para-amino-phenol, with a suitable agent to provide an alphahaloepoxide radical, for example an epichlorohydrin in the presence of a catalytic amount of a lithium compound, for example of hthium chloride and water at a temperature not exceeding 701 C, then subjecting the resulting haiohydrin to dehydrohalogenation, for example with a base tolle quo sodium hydroxide at a temperature between 25 and 800 C.

The reactions involved in this process, in the case of the preparation of the triglycidyl derivative of para-amino-phenol, can be represented by the following equations

The first reaction is carried out by reacting the amino phenol with an 6pichlorohydrin, or other suitable halogenated epoxy compound, in the presence of a suitable lithium catalyst and water at a temperature not not exceeding 70o C and preferably within a temperature range between approximately 25o C and 45o C.

Although the invention is illustrated with reference to a particular type of amino phenol, namely, an amino phenol with one ring, it should be understood that the present invention includes all amino phenols, including amino phenols of the polynuclear type, such as for example <B>la</B> 5-amino-1-naph tol, as well as those which possess in total more than two primary amine and phenol groups, such as for example 4-amino -resoreinol. The invention also includes the use of all-, yl- or halogen-substituted amino phenols. As examples of such amino-

pMnols, there is 2-methyl-4-amino-phenol and <B>the</B> 2-chloro-4-amino-phenol.

Suitable lithium compounds include lithium hydroxide, lithium oxide, and base-generating lithium salts such as lithium chloride, lithium bromide, lithium iodide, lithium, lithium <B>naphthenate</B>, lithium acetate, lithium propionate, lithium <B>la</B> butyrate, etc.

The amount of catalyst used can be varied within wide limits, but it is preferred to use between about 3 mole percent and about five mole percent of the equivalents of the hydroxyl groups present. It is also possible to vary the quantity of water used, but it is preferable to keep between 0.001% and 20% by weight, relative to the total weight of the reaction mixture.

Generally, a greater than stoichiometric amount of halohydrin is used to minimize the formation of undesirable polymeric products which would otherwise form. An amount of approximately three to four times the stoichiometric amount required has been found to provide the most favorable results and the highest yields of the desired polyglycidyl monomers.

The first coupling reaction between 1'6pihalohydrine and amno-phenol is carried out at temperatures not exceeding 700 C approximately. Temperatures above 700°C lead to the formation of excessive amounts of undesirable polymeric compounds. It has been found that temperatures between about 250 C and 450 C are suitable for the mixture, since at these temperatures better yields are obtained, and polyglycidyl derivatives of amino-phenols have better quality. low, however, the longer it takes for the first coupling step of the reaction to occur.

The reaction is allowed to continue for a time sufficient for the substitution of all the replaceable hydrogen atoms for each of the hydroxyl and amino groups present in the amino-phenol. This duration is generally comprised between a minimum uTL of about 10 to 12 hours at temperatures around 450 C and a maximum of about 6 days at temperatures around 25o C.

0n performs the second T6action; dehydrohalogenation of the intermediate halohydrin, after completion of halohydrin formation. It has been found that the best results are obtained by using a quantity of dehydrhalogenation agent, for example of a base such as sodium hydroxide or potassium hydroxide, greater than the stoichiometric quantity corresponding to equation 2 above. It is desirable for this purpose to use an excess ranging from about five percent by weight to about twenty-five percent by weight. 0n adds labasc in the middle

reaction containing the halo! hydrin obtained in the first step of the process. Preferably, the base is added in aqueous solution, for example, an aqueous solution of fifty percent sodium hydroxide can be used. The second step of the process of the present invention is advantageously carried out at a temperature between approximately 550° C. and 60° C., although other temperatures can be used if desired, for example in the range of 25° C. to 25° C. 80oC approximately.

When the dehydrahalogenation reaction is complete, the excess halogenated epoxide, eg, epichlorohydrin, is removed by vacuum distillation. One of the advantages of the present invention resides in the fact that the excess epichlorohydrin can be recovered and reused.

0n then dissolves the first residue of the vacuum distillation dann. a suitable solvent, such as an aromatic hydrocarbon, for example toluene, and then washing the resulting solution with water to strip away mineral salts, for example sodium chloride and excess preservative. dehydrohalogenation which may still be present. The solution thus washed is then distilled under vacuum to remove the solvent used. The residue remaining after this distillation constitutes a product of the present invention, ie the polyglycidyl amino-phenol.

The polyglycidyl products of the present invention generally have an epoxide content of 80% or more, and are substantially free of high degree of polymerization products. By epoxide content, we mean the percentage of theoretical epoxide actually contained in the product. This content can be calculated by dividing the equivalent weight of the polyglycidyl aminophenol puz by the equivalent weight of epoxide contained in the product.

For example, the molar equivalent weight of epoxide for triglycidyl para-amino-phenol is 92. A reaction product having an epoxide equivalent of 115 will have an epoxide content of 92/115 = 80%. 0 .

The products of the present invention are liquids having a high functional activity, and a low viscosity of between 1000 and 5000 centipoise (eps) at approximately 250°C.

The epoxide equivalent is determined by placing in a pressure bottle containing 25 ml of a normal solution of pyridine hydrochloride in pyridine a sample quantity of epoxide calculated to react with approximately 50% of the pyridine chlorohydroxide. The bottle is then closed, and the contents are heated to 900° C. in a circulating air oven for a period of one hour. At the end of this time, the bottle and its contents are cooled and 10 drops of phenol-phthalein indicator (1.0 gram per 100 ml of 60% ethanol) are added. 0n @titrate then the 1st mix until a final permanent red shade, with a titrated solution of alcoholic potash 0.2 N. 0n

also makes a blue test by operating on exactly the same mother, but without introducing a sample. From the titration results obtained, one can calculate the amount of pyridine hydrochloride consumed by the reaction with the epoxide sample, from which one can determine the epoxide equivalent. this value as the number of grams of Sample containing one gram-mole of epoxy.

0n can use los polyglycidyl products of the present invention for the preparation of com positions thermodu.rcissables. Such compositions include the aforementioned products. and a hardener or catalyst known to be suitable for curing epoxy resins. Suitable hardeners include, for example, polyhydroxy phenols, such as bisphenol A, 2,2 bis-(p,ara-hydroxyphenyl), propane, primary and secondary polyamines (for example polycarboxylic acids and their anhydrides (e.g. maMic anhydride, entdo-methylene-tetrahydrophthalic anhydride, or its es, ter alkyl) etc. Suitable catalysts include bases, amines, quaternary ammonium compounds, boge trifluoride complexes (e.g. boron trifluoride complex (e.g. boron trifluoride-piperidine complex, and boron trifluoride-piperidine complex, boron trifluoride-monoethylamine), etc. Primary and secondary amines can behave both as hardeners and as catalysts, ie as combined hardener-catalysts.

The polyglycidyl products of the present invention can be used. in combination with other epoxy resins, if desired, to prepare thermosetting combinations.

To prepare the sanded thermoset compositions of the present invention, the polyglycidyl products are mixed with, sofft (a) 1.e hardener, in a proportion of between 50% and 300% in viro:n of the stoichiometric quantity, when using a hardener; or (b) in the case where a catalyst is used, amounts of catalyst compensated between 0.05% and 7% approximately by weight relative to the weight of polyglycidyl product employed. If desired, the amounts of hardener or catalyst may be varied outside the stated limits, but currently preferred to use quays. .specified here.

By curing agent is meant, wherever the context requires or admits, an expression which includes both catalysts and hardeners, as mentioned above.

The mixture of the glycol derivatives and the curing agents can be carried out at ambient temperature (25° C.) or at a high temperature, up to about 1000 C. The curing agent, such as sofft in solution, is added. Jans a suitable solvent.

0n realizes the cooking of the thermosetting compositions of the present invention Jans suitable molds, at temperatures which can vary widely between ambient temp @ ratu-re and 2000 C depending on the reactivity of the ingredients contained in the composition. Normally, an conducts the cooking operation, if done at high temperature, gradually raising the temperature to the final temperature, and then maintaining this temperature for a few hours. For example, the preferred cook cycle for polycarboxylic acids or anhydrides and aromatic amines is approx. one to two Neures at 75-1000 C, followed by 2 to 16 Neures at 16011-1850 C. With aliphatic polyamines as hardeners, the 1st cure cycle is one to two Neures at room temperature, followed by 2 or 3 Neures at 12011-15011 C. With boron trifluoride complexes, the firing cycle is 4 to 6 Neures at 1000-120" C, followed by 2 to 16 Neures at 160-185 C .

The thermosetting compositions of the present invention are characterized by a high value

of the temperature at which a dHor mation occurs and inne bon: ne chemical resistance. These compositions can be used as epoxy resins, for example for tools or abrasive epoxy grinding wheels, for electric relays, gears, bearings whose mechanical operation would be altered if dimensional changes occur. .due to high temp@ratures. It is also possible to use these compositions with fibers, for example glass fibers, as effective thermal insulation media, such as for the construction of ovens or as envelopes for instruments liable to be subjected to extreme temperatures.

The invention will be better understood by reference to the following examples, where all parts are by weight unless otherwise indicated; these examples are given for illustrative purposes.

<I>Example 1</I> <I>Preparation of the glycidyl derivative of para-antino-</I> <I>phenol</I>

A mixture of 48.4 g (0.444 mole) of para-amino phenol, 370 g of epichlorohydrin (4 moles), 84 g of ethyl alcohol is reacted at room temperature (25o C) for 137 Neures and with stirring. 95% and 0.65% lithium hydroxide monohydrate dissolved in 6 cc of water (3.7 mole percent, based on phenolic hydroxyl equivalents). The mixture is then heated to 55o-600 C and 1'0n adds 66.5 g (1.66 mol) of sodium hydroxide in aqueous solution at 50% by weight, in the space of 3.5 μNures.

The water, alcohol and excess epichlor hydrin are removed by distillation under reduced pressure (30 millimeters of mercury) until the residue reaches a temperature of 65o C. The residue is dissolved in tolu#ne, and wash with water to remove salt and excess Base. The toluene is then removed from the tolu@nic solution of the resulting glyci dyl derivative, by distillation under reduced pressure (30 mm Hg) up to. that the residue has a temperature of 120o C. The resulting liquid, dark in color, has a weight. :equivalent of epoxide of 104 g/g-mole, which represents 88% of the theo-

rie for the 1st triglycidyl ddrive. The viscosity of the product is 1250-1350 cps at 25o C.

<I>Example 2</I> Mix one hundred parts of the product of Example 1 with varying amounts of hardener, consisting of a eutectic mixture of 60 parts of meta phenylene-diamine and 40 parts of 4 ,4'-methylene,dianiline, sold under the trade name Sonite 41 by Smooth-On: Mfg Co. The mixture is prepared at room temperature (250° C.), and poured into 203 mm X 31.7 mm X 6.35 mm moulds. The weight of mixture required to fill the molds is 50 g. The mixtures are poured, the six constituent proportions are indicated in Table 1, and the bars are baked for one hour at 750 C, then for one hour at 100 C, then for 16 hours at 1850 C. The baked bars are then tested to determine their resistance to bending (according to standard ASTM D-790-49 T) and the temperature at which they deform (standard ASTM D-648 457). The results appear Jans. 1st table 1.

<I>Table 1</I> Parts of Sonite 41% parts of triglycidyl para-amino phenol_._.._...._.........._.--__.... ...._..........._..._...._ 15 17 20 23 28 38 Temperature at which deformation occurs, OC ..... 200 202 205 209 199 200 Bending strength at 25o C, kg/cm2 .... <B>------</B> ...<B>--------- ---- --</B> 1183 1078 959 1134 637 728

The maximum temperature: of appearance of the distortion, of 2090 C, is about 600 C higher than that corresponding to a composition of 6ther

diglycidyl ether of bisphenol A: hardness with a comparable quantity of Sonite 41, that is to say with a quantity of hardener necessary to give the diglycidyl ether of bisphenol the highest value of temperature at which produces deformation.

<I>Example 3</I> One hundred parts of the product of Example 1 are mixed with variable quantities, indicated in Table 2, of methyl ester of endo-methylene-tetrahydro anhydride. -phthalc, known commercially as methyl nadic, produced by the National Aniline Division of ALLIED CHEMICAL AND DYE CO. The molded parts, prepared as in Example 2, are baked for 2 hours at 1700° C. then 16 hours at 185° C. The temperature at which the deformation appears is indicated in Table 2.

<I>Table 2</I> Parts of methyl nadir per 100 parts of triglycidyl para-amino-phenol <B>.................. ..... ...... .........</B> 41 67 100 133 167 Temperature at which deformation occurs, o C...... 58 98 152 213 192 The temperature @213o C , which is the highest temperature at which deformation appears, is approximately 800° C. higher than the corresponding temperature for a comparable composition prepared with the glycidyl ether of bisphenol A. <I>Example 4</I> One hundred parts of the product of Example 1 are mixed with varying amounts. -piperidine boron trifluoride complexes, designated under the code name 2083, and sold by the General Chemical Co. The complex can be dissolved in para-aminophenol triglycidyl at 50o C and stored in solution by cooling to room temperature or even below (-180C). This mixture ages very slowly at 25o C and allows the preparation of mixtures presented in the form of one. single package that react to heat. Moldings are prepared as in example 2, and they are baked for 6 hours at 120° C. then 16 hours at 1850° C. Table 3 indicates the temperature at which a deformation appears.

<I>Table 3</I> Parts of BF3-piperidine complex, per 100 parts of triglycidyl para-amino phenol <B>... ......</B>........ 3 5 Temperature at which deformation occurs, 0 C<B>......................</B> ... ........ .. 246 243 These temperatures are approximately 800° C. higher than those corresponding to comparable mixtures containing the glycidyl ether of bisphenol A.

It is thus seen that the products of the present invention are characterized in that they constitute mixtures of epoxides whose deformation occurs at high temperature, when. heats them with conventional catalysts or hardeners for epoxies. It is surprising that the temperature at which deformation occurs is so high compared to the case of polyglycidyl ethers of polyhydroxy aromatic compounds, such as bisphenol A.

Claims (12)

CLAIMS 1. Process for the preparation of glycidyl derivatives of amino-phenols in which each hydrogen atom of each phenolic group and of each primary amino group Lest replaced by a glycidyl radical, characterized @ in: which is reacted an amino-phenol with an alpha-halogenated epoxide in the presence of a catalytic quantity of a lithium compound and water at a temperature not exceeding 700 C and the halohydrin thus formed is subjected to a @dehydrohalogenation at a temperature between 25 and 800 C. . II. Use of the glycidyl derivatives of aminophenols obtained according to the process of claim 1 for the preparation of polymers, characterized in that they are heated in the presence of hardening agents. SUB-CLAIMS 1. Process according to claim I, characterized in that the amino-phenol is para-amino-phenol. 2. Process according to claim I and sub-claim 1, characterized in that the alpha-halogenated epoxide is an epichloithydrin. 3. Process according to claim I, characterized in that the lithium compound is a base-generating compound. 4. Method according to claim I rat sub-claim 3, characterized -in that the lithium compound is lithium -hydroxide or lithium chloride. 5. Process according to claim. I, characterized in that the dehydrohalogenating agent used is sodium hydroxide or potassium hydroxide. 6. Method according to claim I, characterized in that the polyglycidyl derivative obtained has an epoxide content of at least 80%. 7. Process according to claim I, characterized in that a quantity of amino-phenol is used in the reaction equal to three to four times the stoichiometric quantity. 8. Process according to claim I, characterized in that the chlorohydrin is reacted with a quantity of base which is 5 to 25% greater, by weight, than the stoiciluometric quantity of base necessary to effect the dehydrohalogenation of the chlorhydrin. 9. Process according to claim I, characterized in that polyglycidyl derivatives of aromatic compounds having both phenolic groups and amino@primary groups, and whose epoxide content is at least 80%, are prepared, c that is, the number of glycidyl radicals present is at least 80% of the amount obtained by adding the number of phenolic hydroxyls and twice the number of amino groups. 10. Process according to claim I, characterized in that the para-arnino-pih6noltriglyci- dyl is prepared. 11. Use according to claim II, charac terized in that the curing agent is a) an eutectic mixture of meta-phenylenedi-amine and 4,4'-nethylene,dianiline, b) the methyl ester of endo,methylenetetra hydrophthalic anhydride, c) a complex of boron trifluoride and pi-peridin. 12. Use according to claim II, characterized in that the cooking resin mixture comprises 100 parts para-amino triglycidyl phenol and about three to five parts boron trifluoride-piperidine complex.