JP2968668B2 - Photographic paper support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic paper support, and more particularly to a photographic paper support having excellent flatness and excellent durability.

[0002]

2. Description of the Related Art Conventionally, in a photographic printing paper, a polyolefin layer containing kneaded and dispersed white pigments such as titanium oxide is coated on the emulsion coating side surface of the base paper in order to enhance water reflection and light reflection efficiency. Has been done. Usually, a polyolefin layer is also provided on the back surface for water resistance and the like. Polyolefins are excellent in flexibility and processability, and thus are widely used.

However, in recent years, attempts have been made to apply polyester resins having excellent dispersibility of white pigments and high physical strength to such uses, and the usefulness of polyester resins (especially polyethylene terephthalate resins) has been shown. (Japanese Patent Application No. 3-89983) has found that when a polyester resin such as polyethylene terephthalate is used as a water-resistant layer, adhesion to base paper is slightly weaker than that of a polyolefin, and there is a problem in durability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a support for photographic printing paper which is excellent in water resistance, whiteness, flatness and mechanical strength.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned necessary points of improvement, and as a result, obtained a composition obtained by mixing and dispersing a pigment in a resin containing polyester as a main component, on the surface of the base paper on which the emulsion is coated. In the support for photographic printing paper coated with, the average particle diameter in the coating layer is 0.1 μm to 15 μm
Talc and / or kaolin in an amount of 0.1% by weight to 30% by weight to provide a photographic printing paper support having excellent water resistance, whiteness, excellent flatness, and high mechanical strength. I found something wrong.

[0006] Typical examples of the resin containing polyester as a main component include those obtained by a condensation reaction from an aliphatic diol such as polyethylene terephthalate or polybutylene terephthalate and an aromatic dicarboxylic acid. Examples include those obtained by the reaction of an aliphatic dicarboxylic acid, and conversely, those obtained by an aromatic diol and an aromatic dicarboxylic acid. Examples thereof include those obtained by ring-opening polymerization of cyclic esters such as polycaprolactone, and copolymers thereof. Preferably, it is polyethylene terephthalate or a copolymer, polyethylene isophthalate or a copolymer.

As polyethylene terephthalate, in addition to polyethylene terephthalate alone, a mixture of polyethylene terephthalate and another polyester blended at a ratio of 50% by weight or less, or isophthalic acid as a two-base component other than terephthalic acid is used. And, as a glycol component other than ethylene glycol, neopentyl glycol, triethylene glycol, butanediol, using one or more components selected from ethylene oxide adducts of bisphenol A, etc., polyethylene terephthalate component as a main component Also included are copolymers copolymerized as follows. The molecular weight of these polymers is preferably from 30,000 to 50,000.

[0008] The resin layer may be composed of a polyester resin alone, but may be mixed with other resins to form a resin layer. As other resins, for example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-
It can be selected widely from vinyl acetate copolymer, polycarbonate, acrylonitrile polymer, polystyrene, vinyl (co) polymer, polyamide and the like. The amount of the other resin mixed with the polyester resin is 5% by weight to 40% by weight, preferably 5% by weight to 20% by weight.

Examples of the pigment include powders of titanium dioxide, barium sulfate, zinc oxide, calcium carbonate, aluminum oxide, silicon oxide and the like, and solid solutions thereof, among which titanium dioxide and barium sulfate are preferable. The titanium dioxide may be either anatase type or rutile type, but anatase type titanium dioxide is preferred when whiteness is prioritized, and rutile type titanium dioxide is preferred when sharpness is prioritized. A specific product name is K
A-10, KA-20 and the like. The pigment has an average particle size of 0.04 μm to 1 μm, preferably 0.1 μm to 1 μm.
μm to 0.8 μm. If it is smaller than 0.04 μm, it is difficult to uniformly mix and disperse the pigment in the resin, which is not preferable. On the other hand, if the thickness exceeds 1 μm, the surface of the coating film becomes too rough, and the quality of the photograph is deteriorated.

The coating layer on the emulsion-coated side of the base paper is not limited to a single layer, but may be a plurality of layers such as two layers or three layers. The content of the pigment in the coating layer is low in the resin layer on the base paper side and low in the outermost layer. A concentration gradient may be provided to be higher. The outermost layer in the coating layer furthest from the emulsion-coated surface is an important layer that determines the resolution of the photograph, and the highest pigment concentration increases the resolution of the photograph. The pigment concentration in the outermost layer is 10% by weight or more, preferably 20% by weight or more. However, if it is 35% by weight or more, there is a problem that physical properties become brittle and the like, which is not practical. In the layers other than the outermost layer, the pigment may be used in a small amount in order to enhance the damage resistance upon bending, and the content is 10% by weight or less, preferably 7% by weight or less.

In the present invention, talc and / or kaolin having an average particle size of 0.1 μm to 15 μm are contained in the coating layer on the emulsion coated surface of the base paper at a ratio of 0.1% by weight to 30% by weight. As a result, it has been found that an effect of further reducing damage to bending can be obtained.

Talc is hydrated magnesium silicate, and specific examples include those commercially available from manufacturers such as Fuji Talc Co., Ltd. and Nippon Talc Co., Ltd. In addition, examples of kaolin include Kato Kaolin (water stuff), Kanpaku kaolin (water stuff), and the like. Minerals include kaolinite, halloysite, metahalloysite, deckite, nacrite and the like.

When the resin coating layer is composed of one layer, the talc and / or kaolin may be contained in the talc and / or kaolin in an averagely distributed manner in the layer. Alternatively, it is preferable to increase the kaolin content to provide a concentration difference in the layer width direction, or to form the resin coating layer into a plurality of layers and to mainly include the lowermost layer (the layer in contact with the base paper). In addition, talc and kaolin are often flat particles, and it is considered that the reinforcing effect of the film is strongly exhibited. In such a flat particle, a photograph obtained by photographing the particle with an electron microscope is applied to an image processing device (LA525 image processing device manufactured by Pierce Co., Ltd.), and the area of the particle (the average value of the projected area) is obtained. Is defined as the number average particle diameter. In the present invention, the number average particle diameter is preferably from 0.1 μm to 15 μm, and the particle having this particle diameter is the lowermost layer (layer in contact with the base paper). When the content is mainly contained, more excellent durability and flatness can be imparted to the photographic printing paper support.

The above-mentioned particulate additives such as pigments, talc, kaolin and the like include metal salts of higher fatty acids, ethyl higher fatty acids,
Along with dispersing aids such as higher fatty acid amides and higher fatty acids, 2
It is kneaded into the resin by a kneader such as a roll, a roll, a kneader, and a Banbury mixer. Further, an antioxidant can be contained in the resin layer, and the content is preferably 50 ppm to 1000 ppm based on the resin.

The obtained resin composition is coated on a base paper surface to be described later by a melt extrusion method to form a coating resin layer. When a plurality of coating resin layers are formed, the coating is performed on the base paper surface by a melt coextrusion method. It may be formed by coating.

The total thickness of the resin / pigment composition coated on the emulsion-coated side of the base paper is preferably 5 μm to 50 μm, more preferably 15 μm to 40 μm. When the thickness exceeds this range, the brittleness of the resin is emphasized, causing physical problems such as cracking.If the thickness is below this range, the waterproofing which is the original purpose of the coating is impaired and the physical properties become soft. Too undesirable. When the coating layer is composed of a plurality of layers, the thickness of each layer is preferably 2 μm to 25 μm. The preferred thickness of the layer (lowest layer) in contact with the base paper is 2 μm
１８18 μm. It is difficult to form a film having a thickness less than this with a uniform thickness, and if the film has a thickness greater than this, the “effect of making the film less susceptible to bending” of the present invention is less likely to appear.

A resin layer (back coat layer) is also coated on the back side of the base paper (the side opposite to the side on which the photosensitive emulsion is coated).
This resin can be widely used as long as it can be extruded and dissolved in a solvent. Examples include polyesters such as polyethylene terephthalate, polyethylene, polypropylene, nylon, polystyrene, polyvinyl alcohol, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, acrylonitrile resin, polyacrylates, epoxy resin, polyether ketone, and the like. be able to.

This back coat layer is provided for preventing static charge and curling, etc.
No. 020, JP-B-57-9059, JP-B-57-53
940, JP-B-58-56859, JP-A-59-2
No. 14849, JP-A-58-184144 and the like, or an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a surfactant and the like described in or exemplified as appropriate. be able to.

The thickness of the back coat layer is 5 μm to 50 μm
And more preferably 15 μm to 30 μm. If the thickness exceeds this range, the brittleness of the resin is emphasized, and problems such as cracking occur in physical properties. If the ratio is less than the above range, the waterproof property, which is the original purpose of the coating, is impaired and the physical properties become too soft, which is not preferable.

As a method for coating the coating layer on the emulsion-coated side of the base paper and the backside layer, a melt extrusion lamination method and the like can be mentioned.

Examples of base paper include natural pulp paper containing natural pulp as a main component, mixed paper made of natural pulp and synthetic fiber, synthetic fiber paper containing synthetic fiber as a main component, and synthetic resin films such as polystyrene and polypropylene. Any of so-called synthetic papers, which are made into pseudo paper, may be used, but natural pulp paper is particularly preferably and advantageously used as a substrate of a photographic printing paper support. Additives include fillers such as clay, talc, calcium carbonate, and urea resin particles in addition to alkyl ketene dimer, sizing agents such as rosin, higher fatty acid salts, paraffin wax and alkenyl succinic acid, and paper strength agents such as polyacrylamide. And a fixing agent such as a sulfuric acid band are added. Other, if necessary, dye,
A fluorescent dye, a slime control agent, an antifoaming agent and the like are added. Further, a softening agent is added as required.

The pulp surface may be surface-sized with a film-forming polymer such as gelatin, starch, carboxymethylcellulose, polyacrylamide, polyvinyl alcohol, and modified polyvinyl alcohol. As the modified polyvinyl alcohol in this case,
Examples thereof include a carboxyl group-modified product, a silanol-modified product, and a copolymer with acrylamide. When the surface sizing is performed with the film-forming polymer, the coating amount of the film-forming polymer is 0.1 g / m ^{2 to} 5.0 g / m ² , preferably 0.5 g / m ^{2 to} 2.0 g / m ^2. It is adjusted to.
Further, an antistatic agent, a fluorescent whitening agent, a pigment, an antifoaming agent, and the like can be added to the film-forming polymer at this time, if necessary.

The base paper is prepared by subjecting a pulp slurry containing the above-mentioned pulp and additives, such as fillers, sizing agents, paper-strengthening agents and fixing agents, which are added as necessary, to a paper machine such as a fourdrinier paper machine. It is manufactured by papermaking, drying and winding. The surface sizing is performed either before or after the drying, and a calendering is performed after the drying and winding. This calendering treatment can be performed before or after the surface sizing treatment when the surface sizing treatment is performed after drying. However, it is preferable that the calendering treatment be performed in the final finishing step in which various treatments are performed. . In the calendering process, known metal rolls and elastic rolls used for ordinary paper production are used. The base paper is subjected to the above-described calendering process, and is finally adjusted to a film thickness of 50 μm to 250 μm. The density of the base paper ^{0.8g / cm 3 ~1.3g / cm 3} , preferably from ^{1.0g / cm 3 ~1.2g / cm 3} .

As the support for photographic printing paper, various photographic constituent layers are coated and used for color photographic printing paper, for black-and-white photographic printing paper, for typesetting photographic paper, for printing photographic paper, for inverted photographic material,
Silver salt diffusion transfer method It is used for various applications such as negative and positive, for printing materials, and has silver chloride, silver bromide, silver chlorobromide, silver iodobromide, silver chloroiodobromide emulsion layers. The silver halide photographic emulsion layer contains a color coupler,
This is a multilayer silver halide color photographic constituent layer. Further, a silver salt diffusion transfer image-receiving layer containing a physical phenomenon nucleus is provided.

[0025]

According to the present invention, smoothness (glossiness) is achieved by incorporating talc and / or kaolin into a resin layer containing a polyester resin as a main component, which is coated on the emulsion-coated side of the base paper. And a photographic printing paper support having both high mechanical strength and high mechanical strength.

[0026]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

(Example 1-3 and Comparative Example 1-2) A mixture of wood pulp (LBKP / NBSP = 2/1) was beaten to obtain a pulp slurry having a Canadian freeness of 250 cc. Then, after diluting the pulp slurry with water, while stirring, 1.0% of anionic polyacrylamide per pulp (Arakawa Chemical Co., Ltd .: Polystron 195, molecular weight of about 1.1 million), aluminum sulfate 1.0%
% And polyamide polyamine epichlorohydrin 0.1%.
15% (Saimen 557: trade name, manufactured by Dick Hercules) was added. Further, after adding 0.4% of an epoxidized behenamide or an alkyl ketene dimer (a compound having an alkyl group of C ₂₀ H ₄₁ ), sodium hydroxide and cationic polyacrylamide are added to adjust the pH to 7.
5% and antifoam 0.1% were added. The pulp slurry prepared as described above was made into a paper at 180 g / m ² .

The prepared base paper was made to have a water content of about 2% in an oven, and then an aqueous solution having the following formulation was size-pressed as a surface size liquid, and the amount of the applied liquid was 20 g / m2 on the surface of the base paper (photograph emulsion coated side). ² were attached.

Polyvinyl alcohol: 4.0% Calcium chloride: 4.0% Fluorescent whitening agent: 0.5% Antifoaming agent: 0.005% The thickness of the obtained size liquid adhering paper is adjusted to 145 μm by a machine calendar. And used as base paper.

Next, both surfaces of the base paper were treated with a flame treating apparatus manufactured by Kasuga Electric Co., Ltd., the mixing ratio of liquefied propane gas and air was 1/19, and the flame treatment amount was 9.0 KJ / m.
Flame treatment as ² .

On the surface of the flame-treated base paper to be coated with the emulsion,
Using the resin composition shown in Table 1 below, the mixture was melted and mixed at 310 ° C. with a twin-screw extruder and extruded and laminated from a T-die to obtain a resin coating layer having a layer constitution shown in Table 2 below.
The first layer is a layer in contact with the base paper surface, and the third layer is the outermost layer farthest from the base paper surface. Further, as a back coat layer, a PET resin was laminated and coated to a thickness of 30 μm.

[0032]

[Table 1]

¹⁾ Anatase powder without surface treatment

[0034]

[Table 2]

The unit of the film thickness in the table is μm. In order to evaluate the flatness of the obtained resin-coated paper on the side to be coated with the emulsion, the glossiness was measured with a handy gloss meter manufactured by Suga Test Instruments Co., Ltd. The results are shown in Table 3 below.

The mechanical strength was determined by folding the resin-coated paper in an environment of a temperature of 38 ° C. and a relative humidity of 80% with the side to be coated with the emulsion inside, applying a load of 1 kg / 1 cm to the fold, Was opened and the damage of the fold line portion was compared. The results are shown in Table 3 below. In the table, "A" indicates that the swell was small and no swelling was observed, "Good" indicates that the swell was not swelled, but "Not" indicates that the resin coating layer was peeled off and swelled.

[0037]

[Table 3]

As can be seen from Table 3, the photographic printing paper support of the present invention is excellent in flatness (gloss), mechanical strength and durability. On the other hand, when no kaolin or talc is contained, the glossiness is insufficient, the mechanical strength is insufficient, and Comparative Examples 1, 2, 4,
As can be seen from FIG. 5, when the particle diameters of kaolin and talc are out of the range of the present invention, both the glossiness and the mechanical strength are not good.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-127310 (JP, A) JP-A-4-172445 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03C 1/79

Claims (2)

(57) [Claims] 1. A photographic printing paper support in which a composition obtained by mixing and dispersing a pigment in a resin containing polyester as a main component is coated on the emulsion-coated surface of a base paper, the coating layer has an average particle size of 0.1. A photographic printing paper support, characterized in that talc and / or kaolin of 1 μm to 15 μm are contained at a ratio of 0.1% by weight to 30% by weight. 2. A coating layer comprising a plurality of layers, of which the average particle diameter is 0.1
0.1 μm to 15 μm of talc and / or kaolin
2. The photographic printing paper support according to claim 1, wherein the photographic printing paper support is contained in an amount of from 30% by weight to 30% by weight.