Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
1999-01-19
2001-02-20
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C428S195100, C428S211100, C428S537500
Reexamination Certificate
active
06190781
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a resin-coated paper type support for imaging materials which comprises a paper mainly composed of natural pulp as a base, one side of the paper base (hereinafter sometimes referred to as “base paper”) on which an image forming layer is provided being coated with a resin layer (A) containing a resin having film-formability and another side of the paper base being coated with a resin layer (B) mainly composed of a polyethylene resin. More particularly, it relates to a resin-coated paper type support for imaging materials which can provide imaging materials and prints obtained therefrom which are high in gloss appearance, especially, silver halide photographic papers and prints obtained therefrom (print of silver halide photographic paper is sometimes referred to as merely “photographic print” hereinafter), and is superior in cutting properties and curling properties.
Usually, an imaging material comprises a support for the imaging material and an image forming layer provided on the support. For example, silver halide photographic materials, ink jet recording materials, thermal diffusion transfer type thermal transfer recording image materials, heat-sensitive recording materials, and photosensitive-thermosensitive recording materials comprise a support for imaging materials and, coated thereon, an image forming layer such as a silver halide photographic layer, an ink imaging layer, heat-migration type heat transfer recording image layer, a heat-sensitive color forming layer, or a photosensitive heat-sensitive color forming layer, and, if necessary, auxiliary function layers such as a subbing layer, a protective layer and a back layer. Especially, the silver halide photographic layer comprises a silver halide photographic emulsion layer, a protective layer, a subbing layer, an intermediate layer, a color-mingling inhibition layer, an antihalation layer, a filter layer, an ultraviolet absorbing layer, a backing layer and combination thereof. For example, a single silver halide photographic material comprises a support for the photographic material and, provided thereon, a silver halide photographic emulsion layer and a protective layer therefor. Furthermore, a multi-layer silver halide color photographic material comprises a support for the photographic material and, provided thereon in succession, silver halide color photographic constituting layers such as a subbing layer, a blue-sensitive silver halide photographic emulsion layer and an intermediate layer, a green-sensitive silver halide photographic emulsion layer and an ultraviolet absorbing layer, a red-sensitive silver halide photographic emulsion layer and a protective layer.
Hitherto, there has been well known a resin-coated paper type support comprising a base paper coated with a resin having film-forming ability. As supports for silver halide photographic materials, for example, JP-B-55-12584 discloses a technique on supports for photographic materials comprising a base paper coated with a resin having film-forming ability, preferably a polyolefin resin. U.S. Pat. No. 3,501,298 discloses a support for photographic materials which comprises a base paper the both sides of which are coated with a polyolefin resin. Furthermore, since the rapid photographic development process has been applied to silver halide photographic materials, supports for photographic materials which comprise a base paper coated with a polyethylene resin on both sides have been practically used as supports for photographic papers, and, if necessary, the resin layer on the side on which an image forming layer is provided usually contains a titanium dioxide pigment to impart sharpness to images.
Moreover, U.S. Pat. No. 4,774,224 proposes a thermal transfer imaging element having as a support a resin-coated paper of 7.5 microinch-AA or less in surface roughness of the resin coat, particularly, a polyethylene resin-coated paper comprising a base paper coated with a polyethylene resin on the surface. In addition, JP-A-63-307979 discloses an ink jet recording sheet having a resin-coated paper as a support.
However, resin-coated paper type supports for imaging materials which comprise a base paper, especially, a base paper mainly composed of natural pulp which is coated with a resin layer on the side on which an image forming layer is provided still suffer from some serious problems and satisfactory results have not yet been obtained.
First, generally, a resin-coated paper used as a support for imaging materials which is coated with a resin layer containing at least a thermoplastic resin, especially a polyethylene resin on the side on which an image forming layer is provided (hereinafter, the side on which an image forming layer is provided is sometimes referred to as “top side”, the resin layer coated on the top side is sometimes referred to as “top resin layer”, the opposite side is sometimes referred to as “back side”, and the resin layer coated on the back side is sometimes referred to as “back resin layer”) is produced through a series of steps of casting a polyethylene resin composition in the form of a film on a running base paper from a slit die of a melt-extrusion machine to coat the composition on the base paper, press-bonding them between a press roll and a cooling roll, and peeling the resin-coated paper from the cooling roll. In the case of producing a resin-coated paper for imaging materials which is used for obtaining gloss, as the cooling roll there is used a cooling roll of very high smoothness which has a mirror surface, a glossy surface or a finely rough surface mentioned in JP-B-62-19732. Thus, since the top resin layer of the resin-coated paper in molten state is allowed to press-contact with the cooling roll of very high smoothness, this resin layer is processed to have a surface of high smoothness. As a result, imaging materials having said resin-coated paper as a support and prints obtained therefrom should have a visually high glossiness. However, imaging materials having the resin-coated paper as a support and prints obtained therefrom which were actually produced could not have sufficiently high gloss appearance. Especially, as for photographic papers having the resin-coated paper as a support, there could not be obtained photographic printing papers and photographic prints having sufficiently high gloss appearance.
Therefore, the inventors have made various investigations on the factors for the gloss appearance of imaging materials and prints obtained therefrom, and, as a result, it has been found that as the factors affecting the gloss appearance, there are various factors such as resin-coated paper as a support, image forming layer and image forming methods such as development, but the gloss appearance is also greatly affected by the resin-coated paper as a support. The inventors have made further investigations on the factor of the resin-coated paper affecting the gloss appearance, and as a result, it has been found that the gloss appearance of imaging materials and prints is governed by the factor of resin layer and besides by the factors of kind or properties of the base paper mainly composed of natural pulp, for example, kind and fiber length of natural pulp, stock slurry conditions such as additives for paper contained in stock slurry, paper making conditions such as paper making speed, smoothing press, machine calender conditions, after-treating conditions such as size press and tab size press, and, furthermore, surface roughness of the base paper, and other various factors. Moreover, it has been found that with the decrease in thickness of the top resin layer of the resin-coated paper, especially, in the case of 31 &mgr;m or less, the gloss appearance of imaging materials having the resin-coated paper as a support and prints obtained therefrom sharply decreases. Especially, photographic materials for glossy use are required to have a high gloss appearance for prints made from the photographic materials, and photographic materials which give photographic prints
Noda Touru
Tsubaki Masayuki
Hess Bruce H.
Mitsubishi Paper Mills Limited
Pillsbury & Winthrop LLP
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