Ciba-Geigy Corporation

Ciba-Geigy Ag

Heinz Rembold

Friedrich Lohse

Dieter Baumann

Kurt Munk

Alfred Renner

Rolf Schmid

Ewald Losert

Jurg Maurer

Franz R Widmer

Flowable, curable mixtures based on bisphenol epoxy resins cured with anhydrides, and which are modified with di- or triglycidyl-hydantoin compounds, give cured mouldings with improved dimensional stability under heat while having at least unchanged flexibility.

Flowable, curable epoxy resin mixture

A process for producing solder masks on double sided printed circuit boards, comprising conveying the boards beneath a free falling curtain of a pohotopolymer to form a thin layer on a surface of the board, irradiating with ultra violet light areas of the surface other than those that need to be soldered and then, by subsequent development, dissolving the unirradiated areas of the layer. The viscosity of the photopolymer is between 500 to 1200 mPa's at impingement on the surface of the circuit and the height of the curtain is selected so that the rate of flow of the polymer onto the circuit is between 60 to 160 m/min. Also the rate at which the circuits are conveyed beneath the curtain is greater than a rate slightly less than the rate at which the polymer flows onto the circuit.

Process for the production of solder masks for printed circuits

New halogenated bis(cyclopentadienyl) compounds of the general formula ##STR1## in which X represents a halogen atom having an atomic number of at most 35, that is to say a fluorine, bromine or preferably chlorine atom, R.sub.1 and R.sub.1 ' each represents a hydrogen atom or a methyl group, and n = 1, 2, 3 or 4. The monomer of the formula (I) undergoes spontaneous dimerization or oligomerization respectively after it is formed. The oligomer has the formula ##STR2## WHERE P IS 2 TO 20.

Nuclear halogenated .alpha.,.alpha.'-bis(cyclopentadienyl)xylene

Curable mixtures of (a) epoxide compounds, (b) adducts containing mercapto groups, which adducts are produced by an advancement reaction of dimercapto compounds with diglycidyl compounds in an amount less than the equivalent amount, and (c) carboxylic anhydrides. The curable mixtures are suitable as casting resin mixtures, particularly for producing moulded articles of large volume.

Curable epoxide resin mixtures

New polyepoxide-polysiloxanes, which are obtained by mixing in appropriately stoichiometric amounts, an adduct manufactured from a polyepoxide and an acid polyester or a polycarboxylic acid with a polysiloxane and esterifying the mixture, are described. The new compounds can be cured with conventional epoxide resin curing agents, especially cycloaliphatic polycarboxylic acid anhydrides, to give flexible to rubbery-elastic mouldings, which show very low water absorption coupled with excellent dielectric properties and high tracking resistance and arcing resistance.

New polyepoxide-polysiloxane compounds

Polysiloxanes containing hydroxyl groups are manufactured by reacting polysiloxanes, which have been (so-called) advanced with polyols and which contain alkoxy groups, with aliphatic or cycloaliphatic diols in the presence of a catalyst at elevated temperatures. The new polysiloxanols can be used as modifiers for organic resins such as urethane resins or epoxide resins, and give flexible, hydrophobic plastics having valuable mechanical properties.

Polysiloxanes containing hydroxyl groups

Polysiloxanes containing hydroxyl groups are manufactured by reacting polysiloxanes containing alkoxy groups with aliphatic or cycloaliphatic-alipatic diols in the presence of a catalyst at elevated temperatures. The new polysiloxanols can be used as modifiers for organic resins, such as urethane resins or epoxide resins, and give flexible hydrophobic plastics having valuable mechanical properties.

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Arlesheim, Switzerland

Heinz Rembold