Abstract: Disclosed is an ink jet recording sheet which contains in a support and/or in a layer coated on the support a polyvinylamine copolymer obtained from a copolymer of N-vinylformamide and acrylonitrile and having a molecular weight of 50000 or more and containing 20 mol % or more of a vinylamine residue or an ink jet recording sheet comprising a support and an ink-receiving layer provided on the support wherein the composition of the ink-receiving layer contains said polyvinylamine copolymer and ultrafine inorganic pigment having a primary particle size of 100 nm or smaller.

Abstract: An ink jet recording sheet which includes a support including a wood pulp and a pigment, an ink-receiving layer provided on one side of the support and a backcoat layer provided on the other side of the support, wherein the backcoat layer contains a binder containing a synthetic polymer having a glass transition temperature of -50.degree. to +25.degree. C. and at least one water-soluble binder selected from a starch, a polyvinyl alcohol and a cellulose derivative. The ink jet recording sheet is less in undulation caused by absorption of ink after ink jet recording and has a curling resistance hardly susceptible to change in temperature and humidity.

Abstract: Disclosed is an ink jet recording sheet which includes a support mainly composed of a wood pulp and a filler and provided with at least one ink-receiving layer with or without a backcoat layer wherein the ratio of gas permeability/density of the recording sheet is within a specific range. Further disclosed is a method for producing it. The ink jet recording sheet can provide images high in density, excellent in color quality and sharpness and less in feathering, is less in strike-through of ink and cockling and has good image reproducibility.

Abstract: The present invention provides an ink jet recording sheet which includes a support and an ink-receiving layer coated on at least one side of the support wherein the ink-receiving layer contains a coating composition containing a quaternary salt of dimethylamine.multidot.epichlorohydrin adduct represented by the following formula (1): ##STR1## wherein n shows a polymerization degree and is a positive number in the range of 2 to 2000. The ink-receiving layer may additionally contain a (meth)acrylamide-diallylamine copolymer for further effectively inhibiting the color degradation of the image.

Abstract: Disclosed is an ink jet recording sheet which comprises a support mainly composed of wood fibers, an ink-receiving layer provided on one side of the support and a tacky layer provided on another side of the support where a barrier layer comprising a film-forming material is provided between-the support and the ink-receiving layer and/or between the support and the adhesive layer. Spread of ink due to penetration of the adhesive into the ink-receiving layer is prevented and images excellent in sharpness and color quality can be obtained.

Abstract: The invention provides an ink-jet recording medium for forming record images using an aqueous ink containing at least one water-soluble dye selected from direct dye, acidic dye, basic dye, reactive dye and dye for food, said medium containing at least one of acetylene glycol, ethylene oxide addition product of acetylene glycol and acetylene alcohol which have one triple bond in the molecule. This ink-jet recording medium provides images or letters of high density and besides is excellent in ink absorbency.

Abstract: Disclosed is a coat type ink jet recording sheet which has on one side of a support a backcoat layer containing a specific platy inorganic pigment and on another side an ink-receiving layer containing at least one of starch particles, modified starch particles and ethylene-vinyl acetate copolymer resins, and a specific cationic dye fixing agent in such an amount as providing a specific cation charge per unit area of the recording sheet. This ink jet recording sheet is less in curling and cockling in wide ranges of temperature and humidity, improved in runnability on recording apparatuses, high in light resistance and ozone resistance of recorded images and in adhesion of the coating layers, less in blotting of overlapped color ink dots of the recorded images and besides, hardly undergoes yellowing.

Abstract: The present invention provides an ink jet recording sheet which includes a support and an ink-receiving layer coated on at least one side of the support wherein the ink-receiving layer contains a coating composition containing a quaternary salt of dimethylamine.multidot.epichlorohydrin adduct represented by the following formula (1): ##STR1## wherein n shows a polymerization degree and is a positive number in the range of 2 to 2000. The ink-receiving layer may additionally contain a (meth)acrylamide-diallylamine copolymer for further effectively inhibiting the color degradation of the image.