DE1720398C3 - Hardenable epoxy resin compounds - Google Patents

Description

C · NHR ⁵

(H)

C · NR ⁶ R ⁷

Il ο

wherein X has the above meaning, R ⁵ and R ^{6 are} each an alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl or aralkyl group, which may be substituted by halogen, hydroxyl or nitrile, and R is such a group or a Is hydrogen, with the proviso that R ⁶ and R ^{7 can together} with the adjacent nitrogen atom form a heterocyclic ring. Those compounds of the formula II in which X = CH ₂ CH ₂ -; the phenyl radical

40

45

where a is a hydrogen atom and b is a hydrogen atom, Is chlorine, bromine or carboxyl radical or

and

a = -CNHR ⁵

b = -CNR ⁶ R ⁷

C-NR ¹ R ²

^ C-NR ³ R ⁴ O

55 or a cycloalkylene radical

wherein X is either the - CH ₂ (CH ₂ ) _ra CH ₂ radical (where m = 0 or 1) or a substituted or unsubstituted phenylene or cycloalkyl radical to which the two CO groups are bonded through vicinal carbon atoms, and R ¹ , R ² , R ³ and R ⁴ each represent a hydrogen atom or an alkyl, alkenyl ..

or

where c and d are either both hydrogen atoms, or together form a single bond.

Particularly effective and easy to obtain are the compounds of formula II, where R ^{5 is} an alkyl or monohydroxyalkyl group with not more than 4 carbon atoms and either R ^{ft is} such a group and R ^{7 is} a hydrogen atom, or R ⁶ and R ⁷ together with form a morpholine or piperidine group on the adjacent nitrogen and X = - CH ₂ CH ₂ - or o-phenylene.

Examples of compounds of formula 1 which can be incorporated into the compositions according to the invention are Ν, Ν'-dimethylphthalic acid amide, N, N'-din-propylphthalic acid amide, N, N'-bis (2-hydroxyethyl) -phthalic acid amide, N ₁ N '- dibenzylphthalic acid amide, N, N' - dimethylsuccinamide, N ₁ N '- dimethylcyclohexane-1,2-dicarboxamide, N ₁ N' -diethylcyclohex-4-en-l, 2-dicarboxamide, N, N'-dimethyl-3, 6-endomethylene cyclohex-4-ene-1,2-dicarboxamide, Ν, Ν'-diethyl trimellitic acid diamide (e.g. N, N'-diethyl-4-carboxybenzene-1,2-dicarboxamide) and N, N ', N ", N '"- Tetramethylpyromellitic acid tetraamide (e.g. N, N', N", N '"- Tetramethylbenzene-1,2,4,5-tetracarboxamide). The most preferred accelerators are N-benzyl-Ν ', Ν -dimethylphthalic acid amide and N-benzyl-N'.N'-pentamethylenephthal-

acid amide. ,

Epoxy resins which can be used in the compositions according to the invention include e.g. B. polyglycidyl ester, by reacting a di- or polycarboxylic acid with epichlorohydrin or glycerol dichlorohydrin can be obtained in the presence of alkali. Such polyglycidyl esters can differ from derive aliphatic dicarboxylic acids, for example oxalic acid, succinic acid, sebacic acid or dimerized or trimerized linoleic acid and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, Terephthalic acid, naphthalene-2,6-dicarboxylic acid, diphenyl-2,2'-dicarboxylic acid and ethylene glycol - bis (4 - carboxyphenyl ether). Specific such polyglycidyl esters are, for example, diglycidyl phthalate, Diglycidyl adipate, and the diglycidyl esters. which correspond to the average formula

CH ₂ -CH-CH ₂ - (OOC-A-COO-CH ₂ CHOH-CH ₂ ) P-OOC-A-COO-CH ₂ -CH-Ch ₂

in which A is a divalent aromatic hydrocarbon radical, such as a phenyl group and ρ is a small whole or fractional positive number.

Other epoxy resins that can be used include polyglycidyl ethers such as by reacting a dihydroxy or polyhydroxy alcohol or a dihydroxy or polyhydroxyphenol with epichlorohydrin or a related substance (e.g. glycerol dichlorohydrin) under alkaline conditions or, alternatively, in the presence of an acidic catalyst and then Treatment with alkali can be obtained. These compounds can differ from diols or polyols, such as ethylene glycol, diethylene glycol, triethylene glycol, propane -1,2 - diol, propane -1,3 - diol, Butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, Hexane-2,4,6-triol, glycerine or N-aryldialkanolamines, such as N-phenyl diethanolamine, or preferably from dihydroxy or polyhydroxyphenols, such as resorcinol, catechol, hydroquinone, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, bis- (4 - hydroxyphenyl) methane, bis (4 - hydroxypheny I) -methylphenylmethane, Bis- (4-hydroxyphenyl) -tolylmethanes, 4,4'-dihydroxydiphenyl, bis- (4-hydroxyphenyl) -sulfone and in particular of 2,2-bis (4-hydroxyphenyl) propane or phenol / formaldehyde condensation products derive.

It is also possible to use aminopolyepoxides, such as those obtained, for example, by splitting off hydrogen halide from the reaction products of epihalohydrins and primary or disecondary Amines, such as aniline, n-butylamine, bis (4-aminophynyl) methane or bis (4-methylaminophenyl) methane.

Epoxy resins obtained by epoxidizing cyclic and acyclic polyolefins can also be used can be used, such as vinyl cyclohexene dioxide, limonene dioxide. Dicyclopentadiene dioxide, 3,4-epoxydihydrodicyclopcntadienylglycidyl ether, the bis (3,4-epoxydihydrodieyclopentadienyl) ether of ethylene glycol, S ^ -EpoxycyclohexylmethylOVl'-epoxycyclohexanecarboxylate) and its 6,6'-dimethyl derivative, the bis (3,4 - epoxycyclohexanecarboxylate) of ethylene glycol, that of 3,4-epoxycyclohexanecarboxyaldehyde and 1,1-bis (hydroxymethyl) -3,4-epoxycyclohexane formed acetal and epoxidized butadiene or copolymers of butadiene with ethylene-like compounds, such as styrene and vinyl acetate.

Particularly suitable epoxy resins are the epoxy resins obtained by reacting 2,2-bis- (4-hydroxyphenyl) propane obtained with epichlorohydrin in the presence of alkali and which have an epoxy content have from 2.0 to 5.88 epoxy equivalents per kg. To polycarboxylic anhydrides that are used in the inventive Masses that can be used as hardeners include, for example

Phthalic anhydride,

1,2,3,6-tetrahydrophthalic anhydride,

Methylendomethylene-l ^ ö-tetrahydrophthai-

acid anhydride,

Hexachloroendomethylene-l ^ .o-tetrahydro-

phthalic acid anh) drid,

Endomethylene-l ^^ o-tetrahydrophthalic acid-

anhydride,

Hexahydro phthalic anhydride,

Pyromellitic dianhydride,

Maleic anhydride,

Succinic anhydride,

Dodecenyl succinic anhydride,

Polysebacic anhydride and

Polyazelaic anhydride.

The preferred anhydride based hardeners are

1,2,3,6-tetrahydrophthalic anhydride,

Melhylenedomethylene-l ^ Ao-tetrariydrophthal-

acid anhydride.

Hexahydro phthalic anhydride and

Dodcceny succinic anhydride.

The proportions to be used of Polyciul msic anhydride and accelerator hang on such factors as the epoxy content of the epoxy resin used, the nature of the anhydride curing agent, and the curing conditions applicable away. The optimal amounts can easily be determined through routine experimentation.

The compositions according to the invention are suitably supplied as a two-component package, with one component is the epoxy resin and the accelerator of formula 1 and the other is the polycarboxylic acid anhydride hardener contains. The compositions according to the invention can be reactive diluents such as phenyl glycidyl ether or n-butyl glycidyl ether contain. They can also contain fillers, plasticizers and colorants, for example Asphalt, bitumen, glass fibers, mica, quartz powder, cellulose, kaolin, finely divided silicon dioxide or metal powder.

They preferably also contain a polyhydroxy alcohol, such as propane-1,2-diol, as a co-accelerator, Glycerine, a polypropylene glycol or an addition product of one mole of a dihydroxyphenol, in particular 2,2-bis (4-hydroxyphenyl) propane, with 2 or more moles of ethylene oxide or propylene oxide.

The above compounds can be used, for example, as casting, embedding, encapsulation, coating, laminate and tackifier resins can be used.

The following examples illustrate the invention. Unless otherwise stated, "parts" means parts by weight. Temperatures are given in "C. The dimensional stability under heat under load of the cured masses was, unless otherwise stated, determined according to a modified Martens-DIN method, in which a smaller sample, namely 76 mm × 19 mm × 3.2 mm (compared to a sample size of 120 mm × 15 mm × 10 mm as specified in the DIN method) and a maximum fiber stress of 12.5 kg / cm ² (compared to the specified 50 kg / cm ² ) was used However, results are comparable with each other, although they are not exactly equivalent to those obtained by the original method.

The novel accelerators are manufactured as follows:

N.N'-Dimethylphthulsaureamid

20y, (0.13 g-mol) phthalimide in powder form is shaken with 30 ml (0.22 g-mol) 33% aqueous methylamine at room temperature until the imide is dissolved. The mixture becomes worm and after about 3 minutes yellow crystals separate out. The crystals are filtered off and dried in vacuo at room temperature. 18.2 g (70% of theory) of N, N'-DimclhylphlhalsUurcamid TILs white Kristulle are obtained with a melting point of 184-185 ⁰ C; Spring and Woods (J. Chcm. Soc, 1945. 625) give a melting point of 185 "C un.

N.N'-di-n-propylphthalic acidumide

This is made from n-propylamine in a similar fashion. The desired product with a melting point of 134 to 135 "C is obtained by recrystallization from aqueous methanol. The lysis of iron and fluorine for Ci ₄ Hj ₀ NjOj resulted in:

(Minden ... C 68.7. H 8.4. N 10.7%;
calculated ... C 67.8, H 8.1. N 11.4%.

N, N'-bis (2-hydroxyethyl) phthalic acid camide

This is made in a similar way from ethanolamine. The product is obtained as a glass-like solid which cannot be crystallized.

N, N'-dimethyl succinic acid amide

25 g (0.25 mole) of a mixture of succinic anhydride and 33%, 134 ml (1.0 mole) aqueous methylamine are refluxed for 48 hours. Water is removed by vacuum distillation, and the residue is crystallized from ethyl acetate. The product thus obtained has a melting point from 173 to 175 ° C. H u r w i t ζ et al. (J. Am. Chem.

Soc, 1955, 77, 3251) give a melting point of the N, N'-dimethylsuccinic acid amide of 170 to 173 ° Can.

N - Benzyl - Ν ', Ν' - (pentamethylene) - phthalic acid amide

N-Benzylphthalic acid camide is made according to the procedure by V a r a g s (Chem. Abs. 1940,34, 1982). A mixture of 53 g (0.5 mol) of benzylamine, 111g (0.75 mol) phthalic anhydride and 300 ml Glacial acetic acid is refluxed for 1 hour.

Then 100 ml of water are added and the mixture is heated to a boil. On cooling, 79 g (67% of theory) of N-benzylphthalic acid amide separate out. F. 116-117 ⁰ C.

30 g (0.126 mol) of the N-benzylphthalic acid camide thus obtained is heated to 90 C with 12 g (0.141 mol) of piperidine until it has dissolved. The mix will slowly cooled to room temperature. Crystals that separate out are filtered off and made up of ethyl acetate recrystallized. The desired compound of the formula

CNHCH ₂ C ₆ H ₅

CN

is obtained with a yield of 36 g (89% of theory). White crystals. F. 137 139 C. The elemental _{analysis for C 20} H ₂₂ N ₂ O ₂ gives:

Rounded ... C 74.5. H 7.1. N 8.6%:
calculated ... C 74.5, H 6.8, N 8.7%.

N-benzyl-N'.N'-dimethylphthalstureamide

25.5 g (0.1 mole) of N-benzylphosphoric amide. Prepared by the procedure of Varago, see above, it is treated with 68N (1.5Mol) dimethylamine in chloroform for 15 hours at room temperature. After removal of the solvent under reduced pressure, the residue is recrystallized from acetic acid . The product melts at 93 94 C, The Elcmenturuntilysc for C _p H | _H Nj0j gives:

Found ... N 9.72; 9.90%;
calculated .., N 9.93%.

Examples I to 11

An epoxy resin used, hereinafter referred to as »lip Oxydharz I "is designated, is durcl in the usual way Reaction of bisphenol A with epichlorohydrin in the presence of alkali obtained. It owns a

ίο

Epoxy content of 5.11 equivalents / kg and a viscosity of 275 poise at 21 "C. A second epoxy resin used, hereinafter referred to as" epoxy resin 11 " is referred to by reacting such a polyglycidyl ether of bisphenol A with another Amount of bisphenol A received: It has an epoxy content of 3.6 to 4.2 equivalents / kg and a softening point measured by the ring-and-ball method, from about 18 ° C.

Polyhydroxy alcohols incorporated into the hardenable masses are:

"PolyolA": propane-1,2-diol.

»PolyolB«: a bisphenol A / ethylene oxide addition product the formula

/ "V-OCH ₂ CH ₂ OH

"Polyol C": A bisphenol A / propylene oxide addition product of the formula

HIGH ₂ O CH ₃

OCH ₂ CHOH CH ₃

The pot life of the curable compositions, d. H. the time before the masses gel is judged by the fact that mar the time it takes to increase the viscosity of the mass by 15 poise at the specified temperature ' is noted. Pot lives of various compositions are shown in Table I.

Table I.

at Ver 1,2,3.6-Telia- Amide 1 Polyhydroxy To achieve a game turned it hydrophthalic alcohol Viscosity of 15 poise Epoxy
resin acid anhydride 1 at 120 "C necessary time (Parts) (Parts) (Parts) (Min.) - I. O Ν, Ν'-di-n-propylphthal- 1 - . ".. (does not gel after amide 10 days at 150 ⁰ C) - ~ ■ I. O N, N '-di-n-butyl-phthalamide 0.5 - 10 (does not gel after 10 days at 150 C) I. O N, N'-bis (2-hydroxyethyl) - ...... - (does not gel after phthalamide 10 6 days at 150 C) U O N, N-dimethylphthalamide Polyol B 10 (does not gel after 1 6 days) 11th 50 - 0.5 - ~ 500 Il 50 0.5 Polyol B 2 260 Il 50 ... 0.5 Polyol C 10 315 Il 50 Phthalamide 1 109 Il 50 Phthalamide 0.1 117 1! 50 Phthalimide 0.05 Polyol A. > 315 Il 50 Phthalamide 0.1 Polyol B 10 142 .._ U 50 Benzamide 0.05 __ IO 180 I. 11th 50 N.N'-dimethylphthutarnide 0.75 ™. IO <30 2 Il 50 Ν, Ν'-dimethylphtrmlamide 0.5 _— 10 60 3 11th 50 N.N'-dimethylphthalumide 0.5 Polyol B 36 4th Il 50 N.N'-dimethylphthulumid 0.5 Polyol B 10 59 5 11th 50 N, N'-bis (2-hydroxyuthyl).
phthulumid 0.1 Polyol B 44 6th 11th 50 N, N'-bis (2-hydroxyalhyl) -
phthalamide Polyol B 93 7th Il 50 N.N'-dimethyl succinumide 0.1 10 50 8th Il 50 N.N'-dimethylsuccinumide Polyol B 90 9 Il 50 N-Benzyl-N ', N' - (pentu- 0.1 135 methylene) phthalumide lü II 50 N "Benzyl-N ', N' - (pentu- Polyol B 80 methylene) phthulumid 11th Il 50 N-benzyl-N'.N'-dimethyl- 57 phthalamide

Π 20

From the above results it can be seen that the substituted amides, when used alone will have an insignificant hardening effect, but the hardening process of the polycarboxylic acid anhydride accelerate significantly. Phthalic acid amide and benzoyl amide are used in the epoxy resin only after prolonged heating dissolved, whereas the accelerators used according to the invention completely be solved.

Example 12 bis

100 parts of epoxy resin 11 keep the hardenable masses dimensionally stable under load of the cured compositions according to the invention and 50 parts of 1,2,3,6-tetrahydrophthalic anhydride. shown in Table II below. In any case, ίο

Table II

At-accelerator

! Parts)

Polyhydro>; yalkohoi

(Parts of) curing cycle

Heat distortion temperature

N, N'-dimethylphthalamide
N ₁ N '-di-n-propylphthalamide
N, N '-di-n-propylphthalamide

0.05

Polyoi B Polyol B Polyol B

example

10
10
10

4 hours at 130 ° C
24 hours at 130 ° C
24 hours at 130 ° C

4 hours at 130 ° C
24 hours at 130 ° C

not gelled

95 ⁰ C
105 ° C

96 ° C
103 ° C

Samples of a mass containing 100 parts of epoxy resin I ₁ 80 parts of hexahydrophthalic anhydride and two parts of N-benzyl-N ', N' - (pentamethylene) phthalic acid amide are heated to 140 ° C. for various periods of time, the dielectric loss factor (tangent of the loss angle, tg S) of the heated samples is plotted against the curing time in a diagram. The optimum curing time, ie the interval after no significant decrease in dielectric dissipation factor occurs, is found to be 100 minutes. For comparison purposes, the ratio of a common accelerator, N-benzyldimethylamine, which is used to cure 100 parts of epoxy

Tabclle 111

Resin 1 and 80 parts of hexahydrophthalic acid anhydride required after heating to 140 ° C for 100 minutes is determined in a similar manner: This ratio is found to be 0.23 part.

Compositions having the above-mentioned weight ratios of epoxy resin I and hexahydrophthalic anhydride are combined with accelerators aul 4O ⁰ C heated and their viscosities are a Gallcnkamp - compared Torsionsviskosimeter, the degree of rotation of the Viskosimcterdrehkörpcri the viscosity of the mass is inversely proporttona WOBC.

Accelerator (parts)

N-benzyl-N'.N'-tpenylumethylcn) -phthalamide

N-benzyl dimethyl anine 0.23

One can see that the initial principle is casual, whereas the crowd is with the usual Accelerator under these conditions "latent" lsi, 65 mean faster within 5 days d. That is, its effect on the resin has gone too far.

Line VisVosi- meler- nblcsung (Slil. At (Clr.iU of 40 "C) rotation at 40 "C) 6th 330 32 326 54 318 122 316 5 325 29 321 53.5 320 122 311 5 291 30.5 272 51 247 120 gelled

Claims (9)

Patent claims: 1. Curable epoxy resin compositions, consisting of: an epoxy resin, a polycarboxylic anhydride as a hardener for it, a hardening accelerator and possibly a co-accelerator, characterized in that as a hardening accelerator a compound of the general formula Il C-NR ¹ R ² C-NR ³ R ⁴ Il ο wherein X is either the - CH ₂ (CH ₂ ) ", CH ₂ radical (where m = 0 or 1) or a substituted or unsubstituted phenylene or cycloalkyl radical to which the two CO groups are bonded through vicinal carbon atoms, and R ¹ , R ² , R ³ and R ⁴ each represent a hydrogen atom or an alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl or aralkyl group which may be substituted by halogen, hydroxyl or nitrile, and R ¹ and R ² or R ³ and R *, but not both, can be linked to one another to form a heterocyclic ring with the adjacent nitrogen atom, at least one, but not more than three, of R ¹ , R ² , R ³ and R ^{4 being} a Are hydrogen atom, and a polyhydroxy alcohol is optionally used as a co-accelerator, where for 0.4 to 1.1 anhydride group equivalents of the polycarboxylic acid anhydride 1 epoxy equivalent of the 1,2-epoxy resin and for 0.025 to 10 parts by weight of the accelerator 100 parts by weight of 1,2-epoxy resin e nbsp. 2. Compounds according to claim 1, in which the compound of formula 1 is also of formula II C · NHR ⁵ NR ⁶ R ⁷ 55 Il ο adapts, wherein X has the meaning defined in claim 1, R ⁵ and R ^{6 are} each an alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl or aralkyl group which can be substituted by halogen, hydroxyl or nitrile and R ⁷ is such a group or a hydrogen atom, with the proviso that R ⁶ and R ^7, together with the adjacent nitrogen atom, can form a heterocyclic ring. 3. masses according to claim 2, wherein
X = - CH ₂ CH ₂ "
the phenylene radical wherein a is a hydrogen atom and b is a hydrogen atom, chlorine, bromine or carboxyl radical or a = -C * NHR ⁵ and b = —C • NR ⁶ R ⁷
is; or the cycloalkylene radical 'ti wherein c and d are either both hydrogen atoms or together form a single bond. 4. Composition according to claim 2, wherein R ^{5 is} an alkyl or monohydroxyalkyl group having not more than 4 carbon atoms and either R ^{6 is} such a group and R ^{7 is} a hydrogen atom or R ⁶ and R ⁷ together with the adjacent nitrogen atom is a morpholine or Form piperidine, and X = -CH ₂ CH ₂ - or o-phenylene. 5. Compounds according to claim 1, characterized in that the accelerator is N-benzyl-N ', N'-dimethylphthalic acid amide or N-BemzyI-N ', N'-pentamethylene phthalic acid amide. 6. Compositions according to any one of claims 1-5, characterized in that the polycarboxylic acid anhydride 1,2,3,6 - tetrahydrophthalic anhydride, methylendomethylem-l, 2,3,6-tetrahydiophthalic anhydride, Hexahydrophthalic anhydride or dodecenyl succinic anhydride is. 7. Composition according to any one of the preceding claims, characterized in that the epoxy resin is one made by reacting 2,2-bis (4-hydroxyphenyl) propane with epichlorohydrin is obtained in the presence of alkali and an epoxy content of 2.0 to 5.88 epoxy equivalents / kg contains. 8. compositions according to claim 7, characterized in that the polyhydroxy alcohol is propane-1,2-diolglycerol, a polypropylene glycol or an addition product of one mole of a dihydroxyphenol with two or more moles of ethylene oxide or propylene oxide. 9 compositions according to claim 8, characterized in that the polyhydroxy alcohol is an addition product of one mole of 2,2-bis (4-hydroxy-dhenyl) propane with two moles of ethylene oxide or with two moles of propylene oxide. It is known that epoxy resins, i.e. H. Substances with an average of more than one 1,2-epoxy group per Molecule mixed with polycarboxylic acid anhydrides to form tough, infusible solids can be hardened, i.e. hardened, with valuable technical properties. To carry out this reaction it is usually necessary to keep the mixture for a considerable time at a high Maintain temperature, and there were accelerators for curing in to reduce the curing time the epoxy resin / polycarboxylic acid anhydride mixture η incorporated. It is desirable that such accelerators work with the epoxy resin and polycarboxylic acid anhydride can be mixed to form masses which are stable for a suitable period of time at normal use temperatures, that is, that they have an acceptably long pot life, but that they are easily solidified or cured '-can by heating them to a higher temperature'. Substances that have been suggested for use as accelerators include unsubstituted amides, such as urea, formamide, acetamide, propionamide, n-butyramide, benzamide, salicvlamide Adipic acid amide and phthalic acid amide. In some cases the above are unsubstituted Amides hardly soluble in the epoxy resin; this is a disadvantage when e.g. B. is desired, a to produce homogeneous mixture of an epoxy resin and accelerator at room temperature should be stored. Other of these amides only have a moderate accelerating effect. It has now been found that certain substituted amides are used as accelerators and the above-mentioned disadvantages can be alleviated or substantially overcome be able. ., ^ j According to the invention, curable epoxy compositions are made up of an epoxy resin and a polycarboxylic acid anhydride as a hardener for it, a hardening accelerator and possibly a co-accelerator created, which are characterized in that a compound of the curing accelerator general formula Cycloalkyl, cycloalkenyl, aryl or aralkyl group which may be substituted by halogen, hydroxyl or nitrile, and R ¹ and R ² or R ³ and R, but not both, are linked to one another to form a heterocyclic ring with the adjacent nitrogen atom can, where at least one, but not more than three, of R ¹ , R ² , R ³ and R ^{4 are} a hydrogen atom, and optionally a polyhydroxy alcohol is used as a co-accelerator, with 0.4 to 1.1 anhydride group equivalents of the Polycarboxylic anhydride 1 epoxy equivalent of the 1,2-epoxy resin and for 0.025 to 10 parts by weight of the accelerator 100 parts by weight of 1,2-epoxy resin are allotted. Preferred accelerators of the formula I are those of the general formula