Abstract:
The invention relates to a process for coating an electrically conductive substrate, the said substrate being immersed in an aqueous bath based on a cationic synthetic resin binder which is at least in part neutralized with acids and contains amino and/or hydroxyl groups. The said bath contains a mixture of crosslinking agents as well as pigments, fillers, corrosion inhibitors, paint auxiliary substances, and, if appropriate, catalysts, as well as organic solvents in an amount of up to 15% by weight based on the total weight of the coating, the said substrate being cathodically connected. By the action of direct current, a film is deposited on the substrate, after which the said substrate is removed from the bath and the film is cured by stoving, the mixture of crosslinking agents comprising at least two crosslinking agents of different reactivities based on activated esters and/or polyisocyanates blocked by different blocking agents. The expression "different reactivities" means that the crosslinking reaction commences by heating to temperatures which are separated by at least 10.degree. C. and that crosslinking agent which is first to react is present in an amount of 15 to 60 mol %, based on the mixture of the crosslinking agents. This first coat is rinsed and one or more further cathodic coats are deposited before stoving. After each coat has been rinsed, all the coats are cured together.
Abstract:
The invention relates to a self-crosslinking heat-curable binder, in particular for electrocoating finishes, based on an organic synthetic resin which contains primary and/or secondary hydroxyl groups, esterified carboxyl groups and quaternary ammonium groups and can be diluted with water as a result of partial or complete neutralization with acids. The esterified carboxyl groups are activated in the alcohol component by a substituent which has a negative inductive effect.
Abstract:
This application discloses water-dispersible binders which are based on modified epoxide/amine adducts and are the reaction products ofA. polyepoxides having an epoxide equivalent greater than 1 and a mean molecular weight M.sub.n of 140 to 5,000 withB. diphenylolalkanoate esters andC. amines.
Abstract:
The invention relates to water-dispersible binders for cationic electrocoating finishes, which are obtained by reaction of(A) epoxy resins containing low molecular weight aromatic groups and having an epoxide equivalent weight of less than 375 with(B) aliphatic and/or alicyclic polyfunctional alcohols or carboxylic acids having a number average molecular weight of less than 350, further reaction of the product of (A) and (B) with(C) a polyfunctional alcohol having a molecular weight of more than 350, addition at the epoxide groups taking place so that the reaction products of (A) and (B) contain an amount of aromatic groups of from 10 to 45% by weight, calculated as phenylene groups, and further modification of the resulting intermediate with(D) primary and/or secondary amines or ammonium salts in order to achieve the required water-dispersibility. The binders contain, as component (C), 5 to 40% by weight, based on the total binder, of a linear polyalkylene ether diol which has on average one terminal primary and one terminal secondary hydroxyl group per molecule and corresponds to the general formula ##STR1## in which n denotes 1 to 4, preferably 1, and m denotes 4 to 35, preferably 5 to 20.
Abstract:
The invention relates to a selfcrosslinking heat-hardenable binder, in particular for electropaints, which is based on an organic synthetic resin which contains hydroxyl groups and esterified carboxyl groups in the form of carbalkoxymethyl ester groups and is water-dilutable by partial or complete acid-neutralization of amino groups present in the resin.
Abstract:
The invention relates to cathodic water-dilutable binders which contain primary amino groups neutralized with acids and introduced via ketimine groups. The binders have been prepared by reacting(A) a synthetic resin containing epoxy groups with(B) at least one compound which, in addition to a mercapto group which is reactive toward epoxy groups, also possesses at least one ketimine group, and, if required,(C) other modifying compounds, such as, for example, monocarboxylic acids and/or other primary and/or secondary amines,and have then been neutralized with an acid.
Abstract:
The invention relates to water-dilutable binders for cationic electrocoating finishes. For the preparation of the binders, a di-epoxide compound, together with at least one mono-epoxide compound if desired, is converted by a polyaddition, carried out at 100.degree. to 195.degree. C. and initiated by a monofunctionally reacting initiator carrying either an alcoholic OH group, a phenolic OH group or an SH group, to form an epoxy resin which then subsequently is modified with(A) primary and/or secondary amines or their salts and/or the salt of a tertiary amine, a sulfide/acid mixture or a phosphine/acid mixture and with, if desired,(B) a polyfunctional alcohol, a polycarboxylic acid, a polysulfide or a polyphenol.
Abstract:
The invention relates to water-dilutable binders for cationic electrocoating finishes, the said binders containing latent primary amino groups. In order to prepare the binders, an epoxy resin is reacted with a polyamine, which in addition to a sterically hindered primary amino group also contains at least one primary amino group blocked by reaction with a ketone or aldehyde, and, if appropriate, further primary or secondary amines.
Abstract:
The invention relates to an aqueous cathodic electrocoating material which contains a synthetic resin binder containing amino and/or hydroxyl groups and capable of being rendered water-soluble by the addition of an acid. The synthetic resin binder contains a mixture of crosslinking agents, as well as pigments, fillers, corrosion inhibitors, surface coating assistants, if appropriate catalysts, and organic solvents in an amount of up to 15% by weight, based on the total weight of the coating material. The mixture of crosslinking agents consists of at least two crosslinking agents which possess different reactivities and are based on activated esters and/or polyisocyanates blocked with different blocking agents. Different reactivities means that the crosslinking reactions begin at temperatures which are at least 10.degree. C. apart. The crosslinking reagent which reacts first is present in an amount of from 15 to 60 mol %, based on the mixture of crosslinking agents.
Abstract:
The invention relates to a heat-curable binder mixture which comprises an organic synthetic resin A and a crosslinking agent B. Said synthetic resin A can be an epoxy resin, a polyester resin or an acrylate resin having a number average molecular weight of 500 to 20,000 and at least 0.2 equivalent per 100 g of resin of primary and/or secondary amino groups and/or hydroxyl groups, and said crosslinking agent B is an organic compound having at least 2 .beta.-alkoxyalkyl ester groups per molecule.