CH445115A - Hardenable mixtures of epoxy resin, hardeners and flexibilizers - Google Patents

Description

  

  



  Curable mixtures of epoxy resin, harem and flexibilizers
It is known to add compounds to epoxy resins during curing, which make the cured products more flexible. Known flexibilizers of this type for epoxy resins are, for example, polyamides made from dimerized unsaturated higher fatty acids and polyalkylene polyamines (Versamidle), èrner polyalene glycols such as polyethylene glycols and polypropylene glycols.



   These known flexibilizers, however, are relatively highly viscous at room temperature; this means for many applications of the curable epoxy resin mixtures, e.g. B. as casting resin or laminating resin, or as solvent-free paint systems have a significant disadvantage.



   According to the main patent 416 093, certain lactones are of the formula
EMI1.1
 (R = straight-chain alkylene radical or methyl groups as side chains with at least 4 carbon atoms), such as in particular? -Caprolactone, excellent flexibilizers for epoxy resins, which at the same time have a desired low viscosity at room temperature. In addition, after curing, the products generally show a much higher elongation at break than the products cured under otherwise identical conditions, but together with known flexibilizers.



   It has now been found that lactones of the above formula, where in the
EMI1.2
   -Group one of the two hydrogens is replaced by lower alkyl, have similar favorable properties.



   The present invention relates to a curable mixture containing a 1,2-epoxy compound with a 1,2-epoxy equivalent greater than 1, a hardener for such epoxy compounds and a flexibilizer, which is characterized in that the flexibilizer is a lactone of the formula
EMI1.3
 where R is an alkylene radical having either straight-chain or methyl groups as side chains and having at least 4 carbon atoms and preferably 4 to 10 carbon atoms, and R is a lower alkyl radical having 1 to 4 carbon atoms.



   As a lactone of the formula (I) there may be mentioned, for example: α-methyl-E-caprolactone.



   The 1,2-epoxy compounds used as starting materials with an epoxy equivalent: greater than 1 are understood to be compounds which are based on the average number of the molecule. lar weight is calculated n groups of the formula
EMI1.4
 where n is a whole or fractional number greater than 1. These can be terminal or internal 1,2-epoxy groups. Of the terminal 1,2-epoxy groups, 1,2-epoxyethyl or 1,2-epoxypropyl groups are particularly suitable. They are preferably 1,2-epoxypropyl groups which are bonded to an oxygen atom, i. H. Glycidyl ether or glycidyl ester groups.



  Compounds with internal epoxy groups contain at least one 1,2-epoxy group in an aliphatic chain
EMI2.1
 or on a cycloaliphatic ring.



   The known compounds obtainable by the alkaline condensation of epichlorohydrin with polyols are suitable as polyglycidyl ethers. Suitable polyols for the present invention are polyalcohols, such as ethylene glycol, 1,4-butanediol or polyalkylene glycols, and in particular polyphenols, such as phenol or cresol novolaks, resorcinol, catechol, hydroquinone, 1,4-dihydroxynaphthalene, bis- [4-hydroxyphenyl] - methylphenyl methane, bis [4-hydroxyphenyl] tolyl methane, 4,4'-dihydroxydiphenyl, bis [4-hydroxyphenyl] sulfone and in particular 4,4'-dihydroxydiphenyldimethyl methane (bisphenol A).



   For the present invention suitable Polyglyci dyläther correspond to the average formula
EMI2.2
 wherein Z is an integer from 0 to 6.



      Diglycidyl ethers of bisphenol A which are liquid at room temperature contain about 4.8 to 5.6 epoxy equivalents per kg. It is also possible to use higher molecular weight polyglycidyl ethers which are solid at room temperature, with about 0.5 to 3.5 epoxy equivalents / kg.



   Polyglycidyl esters are also suitable, as they are accessible by reacting a dicarboxylic acid with epichlorohydrin or dichlorohydrin in the presence of alkali. Such polyesters can be derived from aliphatic dicarboxylic acids, such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and, in particular, from aromatic dicarboxylic acids, such as phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedic acid , Diphenyl-o, o'-dicarboxylic acid, ethylene glycol bis (p-carboxy-phenyl) -ether u. a. derive. For example B.

   Diglycidyl adepinate and diglycidyl phthalate, as well as diglycidyl ester, which of the average formula
EMI2.3
 correspond, in which X is an aromatic hydrocarbon radical such as a phenylene radical and Z is a whole or small fractional number.



   Suitable epoxy compounds with an inner 1,2-epoxy group are epoxidized diolefins, dienes or cyclic dienes, such as 1, 2, 5, 6-diepoxyhexane, 1, 2, 4, 5-diepoxycyclohexane, dicyclopentadiene diepoxide, dipentendiepoxide and especially vinylcyclohexene; epoxidized diolefinically unsaturated carboxylic acid esters, such as methyl 9, 10, 12, 13-diepoxystearate; the dimethyl ester of 6, 7, 10, 11-diepoxyhexadecane-1, 16-dicarboxylic acid. Mention should also be made of epoxidized mono-, di- or polyesters, mono-, di- or polyacetals, which contain at least one cycloaliphatic five- or six-membered ring to which at least one 1,2-epoxy group is bonded.

   Compounds of the following formulas II to XIII come into consideration as such:
EMI2.4
 
EMI3.1

Further compounds with an inner 1,2-epoxy group are epoxidized diolefin polymers, in particular polymers of butadiene or cyclopentadiene and epoxidized fatty acids, fatty oils and fatty esters. Of the polymers of butadiene, the epoxidized copolymers or addition products with styrene, acrylonitrile, toluene or xylene are preferred.



   Flame-retardant properties of the cured resins are obtained if one starts from those 1,2-epoxy compounds which also contain halogen, such as in particular chlorine or bromine. Examples of such halogen-containing epoxy compounds are: diglycidyl ethers of chlorinated bis-phenols, 2,3-dichloro-1,4-butanediol diglycidyl ether, 2,3-dibromo-1,4-butanediol diglycidyl ether, 2, 2, 3, 3-tetra chloro-1,4-butanediol diglycidyl ether; also compounds of the following formulas XIV-XVII:
EMI3.2
 
EMI4.1

As curing agents for the 1,2-epoxy compounds, basic or acidic compounds are suitable.

   The following have proven to be particularly suitable: amines or amides, such as aliphatic and aromatic primary, secondary and tertiary amines, e.g. B. mono-, di- and tri-butylamines, p-phenylenediamine, 4,4-diaminodiphenylmethane, ethylenediamine, N-oxyethylethylenediamine, N, N-diethylethylenediamine, diethylenetriamine, m-xylylenediamine, triethylenetetramine, Trimethylamine, diethylamine, triethanolamine, Mannich bases, piperidine, piperazine, guanidine and guanidine derivatives, such as phenyldiguanidine, diphenylguanidine, dicyandiamide, urea-formaldehyde resins, aniline formaldehyde resins, polymers of aminostyrenes, polyamides, e.g.

   B. those from di- or trimerized unsaturated fatty acids and alkylene polyamines, isocyanates, isothiocyanates, phosphoric acid, polybasic carboxylic acids and their anhydrides, eg. B. phthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, Do decenylsuccinic anhydride, hexahydrophthalic anhydride, hexachloroendomethylene-tetrahydrophthalic anhydride or endomethylenetetrahydrophthalic anhydride or mixtures thereof: maleic or succinic anhydride, for example. B. resorcinol, hydroquinone, quinone, phenolaldehyde resins, oil-modified phenolaldehyde resins, reaction products of alcoholates or phenolates with tautomeric compounds of the acetoacetic ester type; Friedel-Crafts catalysts, e.g.

   B. AlCls, SbCls, SnCl4, FeCl3, ZnCl2, BFg and their complexes with organic compounds, MetallfLuorborate, z. B. nickel fluoroborate, boroxines such as trimethoxyboroxine.



   The term hardening, as used here, means the conversion of the 1,2-epoxy compounds into insoluble and infusible resins.



   The curable mixtures according to the invention can furthermore contain fillers, active diluents such as butyl glycide, cresyl glycide or 3,4-epoxytetrahydrodicyclopentadienol-8, plasticizers such as dibutyl phthalate or tricresyl phosphate, pigments, flame retardants, release agents, etc., in any phase prior to curing be moved. As extenders and fillers, for example, asbestos, asphalt, bitumen, cellulose, glass fibers, mica, quartz flour, magnesium carbonate, kaolin, chalk flour, sliver flour, colloidal silicon dioxide with a large specific surface (AEROSIL) or metal powder can be used.



   The curable mixtures of epoxy compounds, harem and lactones can be used in the unfilled or filled state, optionally in the form of solutions or emulsions, as impregnating resins, laminating resins, paints, lacquers, dipping resins, casting resins, spreading, filling and leveling compounds, flooring compounds, adhesives, molding compounds , Insulating compounds, for the electrical industry and the like. As well as for the production of such agents.



   In British Patent No. 878 750 curable mixtures of epoxy resins, aromatic diamines and γ-butyrolactone are described as active diluents at room temperature. Such mixtures of epoxy resins, polyamines and butyrolactone, the z. B. are used in surface protection, however, have the disadvantage that the films are heavily clouded, and that the dust-drying times are also relatively long. In contrast, mixtures of epoxy resin, polyamines and e-caprolactone according to the invention have the surprising technical advantage that clear films are obtained, and the dust-drying times are significantly shorter.



   In the following example, parts are parts by weight, percentages are percentages by weight; the ratio of parts by weight to parts by volume is the same as that of the kilogram to the liter; the temperatures are given in degrees Celsius.



   example
Per 100 parts of an epoxy resin (resin A) with an epoxy content of 5.3 epoxy equivalents per kg, which is liquid at room temperature and is known to be produced by reacting bis (4-hydroxyphenyl) dimethyl methane with epichlorohydrin in the presence of alkali a 1st sample mixed with 30 parts of e-methyl-e-caprolactone at room temperature. A second sample does not contain any additive.



   In both samples 10 parts of triethylenetramine are added as a hardening agent at room temperature and mixed.



   To determine the elongation at break, the cast resin samples are poured into the aluminum casting molds described in VSM standard 77101 and cured uniformly at 40 ° C. for 14 hours.



   Elongation at break of the hardened
Sample of casting resin mixtures in / o 1 45
2 1, 6

 

Claims (1)

PATENT CLAIM A hardenable mixture containing a 1,2-epoxy compound with an epoxy equivalent greater than 1, a hardening agent for such epoxy compounds and a flexibilizer, characterized in that the flexibilizer is a lactone of the formula EMI5.1 is where R is an alkylene radical having either straight-chain or methyl groups as side chains and having at least 4 carbon atoms, and R. is an alkyl radical having 1 to 4 carbon atoms. SUBClaim Mixture according to patent claim, characterized in that the radical R in the formula contains 4 to 10 carbon atoms