Abstract: A low dielectric constant composition with a dielectric constant of 4 or less is disclosed. The composition comprises a matrix resin and crosslinked resin particles having an average particle diameter in the range from 0.03 to 10 .mu.m, the crosslinked resin particles being prepared by the polymerization of 1-100 wt % of cross-linking monomers and 0-99 wt % of non-cross-linking monomers, having a dielectric constant of 3 or less, and having a 50 ppm or less average concentration of metal ions. The composition exhibits superior insulation properties and capable of producing an insulating material and sealing material with a low dielectric constant and low dielectric loss tangent (tan .delta.). An insulating material and a sealing material comprising this low dielectric composition and a circuit board provided with the insulating material or sealing material are also disclosed.

Abstract: A water-based maskant composition and a chemical milling method using the maskant composition. Said water-based maskant composition comprises 100 parts by weight (as solids) of a latex constituent consisting of (a) 5-60 parts by weight (as solids) of a copolymer latex obtained by emulsion-polymerization of a monomer mixture consisting of 30-70% by weight of an aliphatic conjugated diene compound, 20-70% by weight of an aromatic vinyl compound, 0-10% by weight of an ethylenically unsaturated carboxylic acid and 0-50% by weight of a vinyl compound copolymerizable therewith and (b) 95-40 parts by weight (as solids) of a natural rubber latex; 10-500 parts by weight of a filler; and 0.1-10 parts by weight of a thickener, wherein the vicosity at 25.degree. C. is 500-5,000 cps as measured by BH type rotor at 20 rpm at a solids concentration of 50% by weight, the pH is 7-9 and the tensile strength and elongation of a film obtained from the composition are 50-150 kgf/cm.sup.

Abstract: An aqueous fluorine-containing polymer dispersion having particle diameters of 0.05-3 .mu.m, which is obtainable by emulsion-polymerizing 5-95 parts by weight of a monomer mixture consisting of at least one monomer selected from the group consisting of alkyl acrylates whose alkyl groups have 1-18 carbon atoms and alkyl methacrylates whose alkyl groups have 1-18 carbon atoms and optionally an ethylenically unsaturated compound copolymerizable with the alkyl acrylates and the alkyl methacrylates, in an aqueous medium in the presence of 100 parts by weight of particles of a vinylidene fluoride polymer; and an aqueous dispersion containing a fluorine-containing polymer which consists essentially of 95-30 parts by weight (in terms of solids content) of said aqueous fluorine-containing polymer dispersion and 5-70 parts by weight (in terms of solids content) of an aqueous dispersion of a water-soluble resin and/or a water-dispersible resin.

Abstract: An aqueous coating composition comprising 15 to 40% (as a solid) by weight of an aqueous copolymer latex. The aqueous copolymer latex is prepared by the emulsion polymerization of monomer components which comprises: (A) 10 to 70 parts by weight of a (meth)acrylate monomer comprising (A-1) 20 to 80% by weight of a branched C.sub.3-5 -alkyl (meth)acrylate and (A-2) 80 to 20% by weight of a linear C.sub.2-4 -alkyl (meth)acrylate; (B) 5 to 30 parts by weight of an ethylenically unsaturated carboxylic acid; and (C) 0 to 85 parts by weight of a monomer copolymerizable with said components (A) and (B). The composition exhibits strong resistance to neutralization, excellent durability, a superior leveling characteristic, superb adhesiveness, high resistance to water-permeation, and good water repellency. It is suitable for coating plastics, ceramics, woods, and formed concrete.

Abstract: Polymer particles composed of particles of a polymer (I) consisting of 96 to 100% by weight of at least one ethylenically unsaturated monomer and 4 to 0% by weight of at least one .alpha.,.beta.-ethylenically unsaturated carboxylic acid, and a (co-)polymer (II) comprising 100 to 10% by weight of a conjugated diolefin which is localized on the surface layer of the particles of the polymer (I) at a (I)/(II) weight ratio of 100/5-100/90. The localized polymer part of the polymer particles is very active, and the polymer particles are easy to modify with a monomer having any functional group, and hence are elemental materials having a high function and being utilizable for various purposes.