CS196155B1 - Epoxy pulverous compositions - Google Patents

Description

The present invention relates to epoxy powder compositions having more advantageous flow properties, especially in applications such as powder coatings or powder adhesives, with improved edge coverage of articles after application and less flowability with functional surfaces.

The flow properties of heterogeneous systems are quite complex, especially when the compositions are liquid and cured at higher temperatures. These properties are mainly influenced by the viscosity of the binder and the amount and type of pigments and fillers.

Various liquid and solid additives are known for conventional solvent types of coatings which affect the thixotropic behavior of the coatings (Haselmeyer P .: Defazet 34, 1977, No. 2, pp. 52-55). However, these additives are not very suitable for powder coatings because they have relatively low efficiency and often lower thermal stability and in these applications tend to have an adverse effect not only on the appearance but also on the mechanical properties of the cured films.

This difficulty in formulating epoxy powder compositions is overcome by the present invention which is based on epoxy compositions based on epoxy resins, hardeners and modifying agents and / or additives selected from the group consisting of accelerators, retarders, plasticizers, plasticizers, flow modifiers, pigments, dyes, fillers, retarders. and thermoplastic or curable macromolecular compounds. The present invention is characterized in that these compositions contain from 0.01 to 10% by weight as flow modifiers. %% Of polar substances with an average molecular weight of 18 to 1 000 with hydroxyl groups bound in an amount corresponding to a ratio of at least one hydroxyl group per 9 g of this substance.

Suitable polar substances affecting the flow properties of the compositions are: water, aliphatic mono-, di-, polyalcohols such as methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, butylene glycol, glycerin, trimethylolpropane, pentaerythritol, and the like; of polyethylene glycol, polypropylene glycol, polyepichlorohydrin, ethylene-4-propylene oxide adducts with phenols and derivatives thereof, such as ethylene-oxidized and propylene-oxidized phenol, p-tert. butylphenol, bisphenol A of various alkylene oxide lengths, ethylene- and propyleneoxidized aliphatic and cycloaliphatic alcohols, polyesters with terminal -OH or -OH and -COOH groups. These polar substances can be used singly or in mixtures.

Low molecular weight and high molecular weight epoxy compounds are suitable for the preparation of the epoxy compositions of the invention. These are mainly polyepoxide compounds obtained by the alkaline condensation of epihalohydrins (epichlorohydrin) and their derivatives or dihalohydrins (dichlorohydrin) with 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, polyglycine 196155 polyethers derived from polyhydric phenols, such as 4,4'-dihydroxydiphenylpropane / bisphenol A), 4,4-dihydroxydiphenylsulfone / bisphenol S), tris- and tetrakis (hydroxyphenylaicans), resorcinol, hydroquinone and phenol-formaldehyde and cresol-formaldehyde polymers, further derived from polyhydric alcohols, in particular from alkylene glycols and polyols. Technically most important are epoxy resins based on 4,4-dihydroxydienepropionone. This group also includes polyglycidyl esters of aliphatic, cycloaliphatic and aromatic polycarboxylic acids, such as adipic acid, sabacic acid, azelaic acid. dimerized unsaturated fatty acids, phthalic, isophthalic, terephthalic, tetrahydrophthalic, hexahydrophthalic, trimellitic, cyanuric and isocyanuric, as well as polyglycidylthiic ethers and polyglycosides. uy,

A second group of polypropoxidinocompounds are aliphatic and cycloaliphatic polyepoxide compounds. Suitable aliphatic epoxides are epoxidized polymers and copolymers of linear conjugated dienes, furthermore epoxy oils, unsaturated esters and unsaturated aliphatic hydrocarbons butadiene dioxide, divinylbenzene (oxide). Cycloaliphatic epoxides include compounds containing cyclopentenoxide Qbis / 2,3-epoxycyclopentyl / ether rings, 2,3-epoxycyclopentanolglycidylether, cyclohexene oxide / 3,4-epoxy-6-methylcyclohexyl-3,4-epoxy-6-methylcyclohexanecarboxylate, vinylcyclohexene dioxide, Dimethylol- (cyclohexenoxide bis-glycidyl ether). cyclooctenoxide, bicycle loheptenoxide and tricyclodecenoxide (dicyclopentadiene oxide, epoxydicyclopentylglycidylene irr).

Further, epoxidized hydroaromatic acetals and ketals, epoxyidated to cyclopentadiene, epoxidized polyesters and other high molecular weight substances, may be mentioned,

The third group of polyepoxide compounds includes polymers and copolymers of unsaturated epoxide compounds such as glycidyl acrylate, glycidyl methacrylate and alkyl glycidyl ether.

(The polyepoxide compounds are used singly or in admixture with each other. Combining them to achieve the desired properties of cured films, e.g., increasing hardness or plasticity. Variations in the properties of polyepoxide compounds are also achieved by modification thereof, e.g., esterification with monomeric or polymeric fatty acids or monoepoxide. compounds and unsaturated polymerizable monomers.

All hardeners suitable for curing epoxy resins such as ethylenediamine, hexamethylenediamine, diethylene triamine, triethylene triamine, N-aminoethylenepiperazine, aminoxylylene diamine, propylcyclohexylamine, 4,4-diaminodicyclohexylamine 4,4'-diaminodiphenylmethane, methenylenediamine, 4,4-diaminodiphenylsulphon, isophorone diamine, piperidine, aminopyridine, trimethylhexamethylenediamine, fatty acid amide amides, tris (dimethylaminomethylamine) 1 / phenol, dicyandiamide and its derivatives, such as substituted biguanides, monoalkyl and amino, 1,1-phenylalkyl and amide, subs. and urea, acid esters, pc. aliphatic and aromatic fatty acids, aromatic and aliphatic anhydrides of organic acids, BF 3 -comoxy.

As reaction accelerators, e.g.

aliphatic polyalcohols (glycerin, glycol, trimethylolpropane, pentaryeryl trit etc.), phenols, cresols, xylenes, salicylic acid and substituted derivatives thereof, such as tris (dimethylaminomethyl) phenol. etc., target. amines such as triethanolamine, quaternary ammonium salts such as trimethylhenzylammonium chloride, and bases derived therefrom, BF-complexes and Lewis acids, thioglycolic acid and its esters, alkali hydroxides, metal fatty acid salts, metal salicylic acid eels, hexamethylene tramin, aminoalkylglycol monoborate, laonoaminopyridine, and the like.

Suitable retarders are, for example, substances containing at least one aldehyde or ketone group in the molecule (acetophenone, benzophenone, fural, furalacetone condensates, ketone resins, etc.).

The powder compositions according to the invention have very well controllable flow properties depending on the type and amount of polar substances used, which depend on the method of application of the compositions in the form of powder coatings or powder adhesives. In view of these particular applications, the type and amount of other additives, in particular fillers, pigments, plasticizers, exibilators, or various macroremolecular substances, are also chosen.

Example 1

100 wt. After pre-grinding, a mixture of solids with 4.4 wt. parts of thanksandiamide, 43 masses, parts of feldspar, mass. parts colloidal S1O2 »4 wt. parts of titanium white, 0.25 wt. part versal blue, 1 wt. of homogenous glycerin and homogenized at 80-100 ° C in a continuous kneader to form a mass which, after cooling, is ground and ground in a pin mill to a particle size of 200-250 µm. The resulting fluidized powder coating composition has a flow rate of 11 mra at 190 ° C and an edge fraction of steel chips of around 55 X. / Flowability is measured by slipping a 3 g tablet over a glass plate inclined at 60 ° for 15 minutes at 190 ° C. and is given in mm./ After curing 15 min / 200 ° C, it has excellent mechanical and electrical properties.

Example 2

Fluid mass prepared according to Example 1, using the same quantity of glycerol containing 4.3 _O 7 wt. water, has a drainage, measured under the same conditions, only 7 mm and an edge coverage of 60%>. It was used as a powder coating for sputtering on electric motor rotors. After curing for 15 min / 200 ° C, a sufficiently thick edge layer was obtained so that the breakdown voltage between the wound conductors and the rotor frame is greater than 1000 V.

Example mass parts of the medium-molecular resin as in Example 1 and 10 wt. parts of epoxy resin having a softening point of 80 ° C and an epoxy equivalent of 0.26 / 100 g, also based on the condensation product Bisphenol A and epiehlorohydrin, are mixed with 6 parts by weight of o-tolylbiguanide, 50 parts by weight. parts of titanium dioxide of the rutile type, 0.25 wt. part versal blue, 1 wt. % by weight of a solid polybutyl acrylate-based coating agent applied to colloidal SiO2 and 1 wt. part of a solid ethylene oxide adduct to phenol of the Antarox 850 type (GAF Corp.). The resulting mixture is homogenized on a continuous kneader at > 10-100 ° C and after cooling, it is ground in a pin mill to a particle size below 100 µm. The resulting powder coating composition is applied in an electrostatic field to metal grids and cured for 10 min at 180 ° C. Very good edge coverage (about 40 Z) is achieved with a very good film appearance and good mechanical properties (digging 8.0 mm, hammer blow 400 mm).

Example 4

Electrostatic powder coating was prepared in a similar manner to Example 3, but instead of ethylene oxide adduct to phenol, 0.5 g of water was mixed with 1.5 g of diethylenetriamine, which was used together with 4 g of thanksandiamide as a mixed hardener. . The resulting material has excellent edge coverage (about 60 Z) and very good mechanical properties after curing for 10 min / 190 ° C. The film shows an orange structure.

Claims (1)

Epoxy powder compositions based on epoxy resins, hardeners and modifying agents and / or additives selected from the group consisting of accelerators, retarders, plasticizers, flexibilators, flow modifiers, pigments, dyes, fillers, flame retardants and thermoplastic or curable macromolecular compounds, Example 5 I00 wt. parts of a medium molecular epoxy resin with a softening point of 98 ° C and an epoxy equivalent of 0.099 / 100 g are mixed in malaxer at 80 ° C with> 0 parts by weight of diglycidyl ester of hexahydrophthalic acid and 8.5 parts by weight of a mixed hardener; wt. From o-tolylbiguanide and 30 wt. From dicyandiamide, further with 5 wt. parts of polyvinyl butyral and 2 wt. parts of trimethyloipropane. After cooling, the resulting composition is crushed in a pin mill to a powder and is used as a 20 min / 180 ° C cured powder adhesive with excellent mechanical properties (shear strength of 40 MPa and peel strength of 3.5 MPa) and minimum flowability curing. The invention is characterized in that it contains from 0.01 to 10 wt. Of polar substances having an average molecular weight of 18 to 1000 with hydroxyl groups bound in an amount corresponding to a ratio of at least one hydroxyl group per 9 g of this substance.