CS202400B1 - Method of preparing pulverous compositions of epoxy resins - Google Patents

Description

It is an object of the present invention to provide a process for preparing epoxy powder compositions with selectable flow properties, in particular as powder coatings or powder adhesives, and improved edge coverage of coated articles and less flowability with functional areas.

The flow properties of homogeneous systems are mainly due to the viscosity and reactivity of the basic components of the composition, such as hardeners and additives, as opposed to heterogeneous systems formed with binders with pigments and fillers, which are quite complex matters. Moreover, their properties are influenced by the viscosity of the binder, the concentration and type of pigments and fillers, the presence of thixotropic additives, the degree of dispersion and the like (Haselmayer F .: Defazet 31, 1977, No. 2, pp. 52-55). Control of flow properties of heterogeneous systems is relatively difficult, especially when thermosetting ayatemes are initially liquid and become solid during curing. E.g. in epoxy systems, this control is limited by the type of epoxy resin of different molecular weight and the type of hardener. The viscosities of the compositions cured at high temperatures do not initially differ greatly, so the choice of hardener used is very narrow and flow properties need to be adjusted by the concentration and type of filler, the addition of thixotropic additives, which often adversely affects end product properties such as corrosion resistance, electrical properties and mechanical properties of films.

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The present invention is directed to a process for the preparation of powdered compositions based on epoxy resins, hardeners and additives from the group consisting of accelerators, retarders, plasticizers, extenders, fillers, pigments, dyes, thermosetting and thermoplastic polymers. SUMMARY OF THE INVENTION The present invention is characterized in that these compositions, when homogenized in the presence of 2 to 70 parts by weight of a latent hardener selected from dicyandiamide and its derivatives, substituted urea and melamine, acid esters, polyacids of aliphatic and aromatic, aliphatic 1 aromatic organic anhydrides, - complexes and aromatic diamines and 1 to 35 wt. parts of the reactive hardener from the group of primary and secondary aliphatic, cycloaliphatic, heterocyclic amines are pre-reacted at a temperature of 20 to 150 ° C for 1 to 120 minutes until the conversion of the epoxide groups 2 to 45% »

The resulting viscosity and flowability of the coatings applied depend not only on the homogenization conditions but also on the concentration of the reactive hardener used, as shown in the table below.

Tab. 1 Dependence of viscosity, spattering and conversion of epoxide groups on diethylenetriamine content during homogenization of CHS mixture ΕΡΟΧΪ 1/16-dicyandiamide-diethylenetriamine on continuous BUSS kneader

Epoxy 1/16 eq. 1 1 1 1 Dicyandiamide eq. 1.9 1.9 1.9 1.9 Diethylentrlamine equiv. 0 0.25 0.35 0.4 ° C / min 110/2 110/2 110/2 110/2 % Conv. (Epoxy) 2.3 27.3 28.5 43.3 Viscosity in mPa. 10 “^ 15.4 69.4 208.3 299.9 Run down at 190 ° C in mm > 200 180 66 16

Of the reactive hardeners, all years suitable for curing epoxy resins such as ethylenediamine, hexamethylenediamine, diethylenethylamine, triethylenetetramine, N-aminoethylenepiperazine, xylylenedlamine, bis (N-cyclohexyl-3-aminopropyl) amine, N, -propylsenediamine, 4,4'-diaminodicyclohexylmethane, isophorone diamine, piperidine, aminopyridine, trimethylhexamethylenediaine, fatty acid aminoamides, triethylenethylamine, dimethylaminomethylamine, dimethylaminomethyl amine, dimethylaminomethyl amine, dimethylaminomethyl amine, dimethylaminomethyl amine, dimethylaminomethyl amine, dimethylaminomethylamine, with said amines, hydroxystyldiothylenetriamine, cyanoethylated polyamines, acid amine salts, Schiff bases and primary amine blocked ketones.

Among the latent hardeners are dicyandiamide and its derivatives such as substituted biguanides, monoethyloldicyandlamide, 1-phenyldicyandiamide, substituted ureas and melamines, acid esters, aliphatic and aromatic polyalcohols, aliphatic 1 aromatic anhydrides of organic acids, BF-methodiphenylsulfine, diamine, diphenyl diamine, diamine, diphenyl diamine, diamine, 4,4'-diaminodiphenylmethane and the like.

Both low molecular weight and high molecular weight epoxy compounds are suitable for the preparation of the epoxy compositions of this invention. These are mainly the poles of the epoxy compound obtained by the alkaline condensation of epihalohydrins (epichlorohydrin) and their derivatives or dihalo3.

202 400 hydrins (dihydrofluorine) β substances whose functional groups contain at least two active hydrogen atoms. They also include epoxy compounds obtained by epoxidation of unsaturated compounds and polymers or copolymers containing epoxy groups.

The first group includes in particular polyglycidyl ethers derived from polyhydric phenols, such as 4,4'-dihydroxydiphenylpropane (bisphenol A), 4,4'-dihydroxydiphenylsulfone (bisphenol S), tria- and tetrakis (hydroxyphenylalkanes), resorcinol, hydroquinone and phenolformaldehyde. cresol-formaldehyde novolaks, further derived from polyhydric alcohols, in particular from alkylene glycols and polyalkylene glycols. Technically the most important are epoxy resins based on 4,4'-dihydroxydiphenylpropane. This group also includes the glycidyl esters of aliphatic, cycloaliphatic and aromatic polycarboxylic acids, such as adipic acid, sebacic acid, azelaic acid, dimerized unsaturated fatty acids, phthalic, isophthalic, terephthalic, trimellitic, cyanuric and isocyanuric acid, polyglycid lamina.

A second group of polyepoxide compounds are aliphatic and cycloaliphatic polyepoxide compounds. Suitable aliphatic epoxides are epoxy polymers and copolymers of linear conjugated dienes, epoxidized oils, unsaturated esters and unsaturated aliphatic hydrocarbons (butadiene dioxide, divinylbenzene dioxide). Cycloaliphatic epoxides include cyclopentenoxide-containing compounds (bis (2,3-spoxycyclopentyl) ether, 2,3-epoxyeyclopentanol glycidyl ether), cyclohexenoxide (3,4-epoxy-6-methylcyclohexyl-3,4-epoxy-6-methylcyclohexanecarboxylate, vinylcyclohexene dioxide, 1,1-dimethylene glycide) ), cyclooctenoxide, bicycloheptenoxide and tricyclodecenoxide (dicyclopentadiene dioxide, epoxydicyclopentylglyoidyl ether). Further, epoxidized hydroaromatic acetals and ketals, epoxidized polycyclopentadiene, epoxidized polyesters and other high molecular weight substances can be mentioned.

The third group of polyepoxide compounds include polymers and copolymers of unsaturated epoxy compounds such as glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether.

The polyepoxide compounds are used singly or in admixture with each other. Their combination achieves the desired properties of the cured films, such as increasing hardness or plasticity. Variations in the properties of the polyepoxide compounds are also achieved by modifying them, for example by esterifying with monomeric or polymeric fatty acids, or by adding monoepoxide compounds and unsaturated polymerizable monomers.

As reaction accelerators, for example, aliphatic polyalcohols (glycerin, glycol, trimethylolpropane, pentaerythritol, etc.), phenols, cresols, xylenols, ealicylic acid and substituted derivatives thereof, such as tris (dimethylaminomethyl) phenol and the like, can be used. amines such as triethanolamine, quaternary ammonium salts such as trimethylbenzylammonium chloride, and bases derived therefrom, BFycomplexes and Lewis acids, thioglycolic acid and its esters, alkali hydroxides, metal fatty acid salts, metal chelates of salicylic acid, hexamethylenetetramine, hexamethylenetetramine, hexamethylenetetramine, hexamethylenetetramine; , substituted ureas, etc.

Retarders can be used, for example, with substances containing at least one aldehyde or ketone group in the molecule (acetophenone, benzophenone, fural, furalacetone condensates, ketone resins, etc.).

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The compositions according to the invention have very well controllable flow properties depending on the type and amount of latent and reactive hardeners, which are governed by the manner of application of the compositions in the form of powder coating and molding compositions or powder adhesives. With respect to these particular applications, ee selects the type and amount of other additives, especially fillers, pigments, plasticizers, flexibleizers or even various macromolecular substances.

Example 1

100 wt. After grinding the bulk material mixer with 4.4 wt. parts (1.9 eq.) of dicyandiamide and 1.374 wt. 50 parts by weight of a solid mixture of diethylenetriamine-aerosil (1: 1) (0.3 eq.) were added. parts of feldspar, 20 wt. parts SiO ₂ drift, 3 wt. parts of chromium oxide, 2 wt. parts of a polyacrylate-based solid flow agent. The mixture is homogenized in a continuous BUSS kneader at 100 ° C / 3 min. After cooling, the mass is crushed in a hammer mill to a particle size of 20-200 / un. The viscosity of the mass at 120 ° C is ca 2.10 µmPa.s, the conversion is 30% and the flow rate at 190 ° C is 7-10 mm. The powder obtained can be used for fluidized bed coating with good edge coverage up to about 70% of thickness on flat surfaces of coated metal objects.

Example 2

100 wt. parts of the epoxy resin described in Example 1 are mixed with 3-5% by weight of the bulk material mixer after grinding. % (1.5 eq.) of dicyandiamide; and 8 1.156 wt. part by weight of the mixture of cyclohexylpropylenediamine-aeroail 200 (1: 1), 50 wt. parts of titanium white, 3 wt. parts of solid flowing agent based on polyacrylates. The resulting bulk mass is homogenized in a continuous kneader at 110 ° C / 3 min. After cooling, the mass is crushed in a pin mill to a particle size below 100 µm. The viscosity of the mass at 120 ° C was 3.5 · 1ΟΟ mPa · s, flow rate 200 mm at 190 ° d, conversion of epoxy groups 15%. The powder obtained can be used as a powder paint for electrostatic spraying β by excellent flow, rapidly curing at 180 ° C and β by good coverage of the edges coated with pre-coated up to 55% of the thickness.

Example 3 wt. parts of the epoxy resin described in Example 1 and 20 wt. epoxy resin parts by epoxy. equivalent to 0.26 / 100 g and a softening point of 80 ° C is ground and mixed in a solids mixture of 5.28 wt. % (2 equiv.) of dicyandiamide and β 2.17 wt. (0.4 equivalents) of piperazine, 5 wt. parts of ferric iron oxide, 10 wt. parts of feldspar, 10 wt. parts SiO ₂ drift, 2 wt. parts of Zn phosphate, 2 wt. parts of benzoin. The resulting mixture is homogenized at 140 ° C for 5 min in a continuous batch and after cooling, it is ground to a powder having a viscosity at 120 ° C of 1.10 * mPa.s and a descending flow of 2-3 mm at 190 ° C, epoxy group conversion of 21% »The powder is suitable as a fluid mass for coating steel pipes at 220 ° C.

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Example 4

100 wt. parts of triglycidyl isocyanurate by epoxide. eq. 0.90 / 100 g and a melting point of 91 [deg.] C. were mixed with a 55 wt. parts by weight of diaminodiphenylsulfone (1 eq.), 6.12 wt. part (0.1 eq.) of p-xylylenediamine in a mixture with aerosol 380 in a ratio of 1; 1, with 5 wt. parts of polyvinyl butyrate and the resulting mixture was homogenized in a continuous kneader at 80 ° C for 1 min and cooled. The resulting mass was milled to a powder having a viscosity at 120 ° C of 4.10 mPa · e, a run-off at 190 ° C of 25 mm, an epoxide conversion. groups 42%. It can be used as a thermoreactive adhesive with excellent mechanical properties.

Example 5

100 wt. parts of cresol novolac condensate epoxy resin with epichlorohydrin with an epoxy equivalent of 0.45 / 100 g and a softening point of 74 ° C are ground and mixed in a solids blend with 6 wt. parts by weight of BF-β-ethylamine complex and 14.4 wt. % of triethylene tetramine in ee siloxide (1: 1) (0.5 eq.), 70 wt. parts of ground slate, 15 wt. parts of zinc stearate and homogenized on a calender at 80 ° C and for 2.5 min to a solid which, after cooling, is ground to a powder. The resulting powder has a viscosity of 3.10 µmPa.s at 120 ° C and can be used as a molding composition which can be cured at 180 ° C and at a pressure of 8 MPa for 10 min. The material has high resistance (160 ° C Martens) and good mechanical properties.

Example 6

100 wt. parts of the epoxy resin shown in Example 1 are ground and mixed with 3.6 wt. % tolylbiguanide (1 eq.) and 1.7 wt. % of a mixture of isophorone diamine with SiO ₂ drift (1: 1) (0.2 eq.), followed by 50 wt. parts Ti0 ₂ , 1 wt. part by weight of ethylene vinyl acetate; parts of a solid flow agent based on polyacrylates, in combination with a silicone resin. This mixture is homogenized on a continuous BUSS kneader at 85 ° C for 2 min. The resulting mass, after cooling, is ground to a powder having a viscosity at 120 ° C of 5.10 µmPa.s and a flowability at 190 ° C of 60 min. The powder obtained can be used as a powder coating for electrostatic application to metal rugged articles with very good edge coverage on a smooth, leveled surface. ,

Example 7

100 wt. parts of the triglycidyl isocyanurate described in Example 4 are mixed with 60 wt. parts of an acid ester based on hexahydrophthalic acid, followed by a mixture of polyols (ethylene glycol, dianol, glycerine) with a softening point of 95 ° C and 8 wt. parts by weight of a mixture of N-aminoethylpiperazine and aerosol 300 (1: 1) and 2 wt. parts by weight of an acrylate-based flow agent, at the same time 40 wt. parts by grinding, partially fired kaolinic filler, 5 wt. The mixture was homogenized on a BUSS kneader at 150 ° C for 3 min. The resulting mixture after cooling is ground and used as a fluid mass for coating metal articles for outdoor use. The material has a very good edge coverage a at 180 ° C

202 400 low drainage at 180 ° C, 3 mm; the viscosity obtained during homogenization was 5.10? mPa.s at 140 ° C, epoxide conversion. groups 42%.

Example 8

100 parts by weight of epoxy resin based on the condensation product of diane and epichlorohydrin with epoxy. equivalent of 0.49 / 100 g is homogenized on a calender at 30 ° C for 1 h and 15 wt. parts by weight of dicyandiamide and 3.5 wt. % of diethylenetriamine; parts S10 ₂ drift to a viscous semi-solid, which can be used as a thermoreactive adhesive for metals cured at 190 ° C / 15 min. The resulting ellipses have good mechanical properties at higher operating temperatures.

Claims (1)

A process for the preparation of epoxy powder compositions with selectable flow properties comprising epoxy resins, hardeners and additives from the group comprising accelerators, retarders, enhancers, pigments, dyes, fillers, thermoplastic and thermosetocyte gauges, characterized in that the composition is homogenized in the presence of 2 to 70 parts by weight of a latent hardener from the group of dicyandiamide and its derivatives, substituted urea and melamine, acid ethers, polyacids of aliphatic and aromatic, aliphatic and aromatic anhydrides of organo-acid acids, BF-complexes and aromatic diamines and 1-35 parts by weight of a reactive hardener from and secondary aliphatic, cycloaliphatic, heterocyclic amines are allowed to react at 20 to 150 ° C for 1 to 20 minutes to convert epoxide groups of 2 to 45%.