JPH03100648A - Base for photographic printing paper - Google Patents

Abstract

PURPOSE:To restrain fog of a photographic printing paper from increasing with time lapse by forming an interlayer containing a polymer and a specified amount of radical capturing agent between a sheet of a base and a layer containing an electron beam-hardened resin. CONSTITUTION:The base to be used is obtained by forming the interlayer containing the polymer and the 1,000 - 10,000 ppm radical capturing agent on the sheet of the base and on this interlayer the layer containing the electron beam-hardened resin, thus permitting free radicals remaining in the electron beam-hardened resin-coated layer to be captured by the radical capturing agent contained in the interlayer, and therefore, occurrence of fog due to time lapse in the photographic emulsion layer formed on this layer to be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a support for photographic paper. More specifically, the present invention relates to a support for photographic paper that can suppress fogging of a photographic emulsion layer.

[Conventional technology]

Traditionally, supports for photographic paper have been made by coating both sides of a paper base with a polyolefin resin film, which has excellent water resistance.
It is widely used because it is suitable for speeding up the development process.

Such polyolefin resin coatings contain inorganic white pigments such as titanium oxide and rhusium carbonate to increase the hiding power of the support, thereby improving the resolution and sharpness of the photographic emulsion layer coated thereon. It enhances sexuality.

However, when forming a coating layer of polyolefin resin on a sheet-like substrate, approximately 300% of polyolefin resin is used.
It is necessary to melt it at a high temperature of °C and laminate it onto the substrate surface, but such high temperatures easily cause polyolefin to thermally decompose, causing yellowing and pinholes on the coated surface. There were drawbacks.

In addition, in such a high-temperature molten polyolefin resin, volatile components in the pigment may cause foaming during extrusion and poor dispersibility, and for this reason, it is not recommended to blend a large amount of the above-mentioned inorganic white pigment. However, there is a limit to the amount that can be added, and therefore there is a problem in that high resolution, clarity and sharpness of photographic images cannot be obtained.

Therefore, in order to solve the above problems, a mixture 1 composition containing an unsaturated organic compound that can be cured by electron beam irradiation and an inorganic white pigment was coated on a sheet-like substrate, and this was then irradiated with an electron beam. to form a coating layer,
It is known to produce supports for photographic paper thereby (JP-A-57-27257 and JP-A-57-49946). When such a support is used, it is possible to increase the amount of inorganic white pigment in the resin coating layer to 20 to 80% by weight, and as a result, the resolution and sharpness of the resulting image on the photographic paper are improved. is significantly improved compared to photographic paper having a coating layer mainly composed of polyolefin resin.

However, it has become clear that the photographic paper support having the electron beam-cured resin coating layer described above has the following new problems.

In other words, if photographic paper obtained by coating a photographic emulsion on a coating layer mainly composed of resin cured by electron beams is developed after the normal storage time, the image will be fogged and the so-called aging will occur. The problem is that the occurrence of fogging increases.

Although various studies have been made to improve this fog over time, no sufficiently effective measures have been established yet.

[Problem to be solved by the invention]

The present invention aims to provide a support for photographic paper in which even when an electron beam-cured resin coating layer is formed on a sheet-like substrate, fogging over time in the photographic emulsion layer formed thereon is less likely to occur. be.

[Means and actions to solve the problem]

The support for photographic paper of the present invention includes a sheet-like substrate and an intermediate layer formed on at least one surface of the substrate and containing a polymer compound material and 1.000 to 10.000 ppm of a radical scavenger. and formed on the intermediate layer,
and a coating layer containing an electron beam-cured resin cured by electron beam irradiation.

In the photographic paper support of the present invention, an intermediate layer containing a radical scavenger and a polymer compound is formed on at least one side of a sheet-like substrate, and then an electron beam curable A mixed composition containing a resin and an inorganic white pigment as main components is applied and irradiated with an electron beam to form a coating layer made of an electron beam-cured resin.

The cause of fogging over time is not yet fully clear at present, but it is caused by residual radicals in the electron beam-cured resin coating layer, especially in the cured resin coating layer, diffusing into the photographic emulsion layer. This is thought to be one of the causes.

Therefore, when a radical scavenger is included in the intermediate layer made of a polymer compound, the residual radicals in the electron beam-cured resin coating layer are captured by the radical scavenger, and as a result,
It is thought that fog in the photographic emulsion layer is reduced over time.

The radical scavenger used in the present invention includes 1.1
-diphenyl-2-picrylhydrazyl, 1.3.5-
) Riphenylfeldazil, 2.2゜6.6-tetramethyl-4-piperidone-1-oxynope N-(3-N-
oxyanilino-1,3-dimethylbutylidene)-aniline oxide, high valent metal salts such as ferric chloride, diphenylpicrylhydrazine, diphenylpicrylhydrazine, diphenylamine, hydroquinone, t-
Butylcatechol, dithiobenzoyl disulfide, p
, p'-ditolyl trisulfide, benzoquinone derivatives, nitro compounds, and nitroso compounds. Among these, it is particularly preferable to use hydroquinone. Further, the above radical scavengers may be used alone or in combination of several types.

The content of the radical scavenger in the intermediate layer is 1.000 to 10.000 ppm based on the polymer compound. If this content exceeds 10.000 ppm, the curing of the electron beam curable resin coating provided on the upper layer is suppressed, and sometimes a sufficient curing reaction may not take place. Also,
If the content is less than 1.000 ppm, the objective of the present invention, which is to reduce fog over time, cannot be achieved.

In the present invention, examples of the polymer compound contained in the intermediate layer include styrene-butadiene rubber, acrylonitrile-butadiene styrene resin, vinyl acetate resin, vinyl acetate-
Examples include acrylic acid copolymers, acrylic ester resins, and polyurethane resins. These resins can also be used as emulsions through the use of surfactants. Furthermore, along with the above-mentioned polymer compounds, gelatin, polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, starch, oxidized starch, dialdehyde starch,
Water-soluble polymer compounds such as casein may also be used. An intermediate layer is formed by applying a coating agent prepared by mixing a radical scavenger and containing these polymer compounds as a main component onto a sheet-like substrate and drying the coating agent.

In this case, the coating amount for forming the intermediate layer is 0.15 by dry weight.
It is desirable that it be in the range of ~7 g/m'. If the weight of the intermediate layer is less than 0.15 g/m'', it will not be possible to achieve the objective of the present invention of reducing fog over storage.Also, even if the coating amount is 7 g/m'' or more, No improvement in effectiveness can be expected. Therefore, a particularly preferable coating amount is 0.
5 to 5 g/rn'.

The electron beam curable resins that can be cured with electron beams used in the present invention include acrylic oligomers containing two or more carbon-carbon double bonds in one molecule, methacrylic oligomers, and polyfunctional acrylic oligomers. monomers, and monofunctional acrylic monomers and vinyl monomers containing at least one carbon-carbon double bond in one molecule. These electron beam curable resins are irradiated with electron beams to generate radicals and polymerize, and also cause intermolecular crosslinking reactions to be cured to form a resin coating layer.

Examples of electron beam-curable acrylic and methacrylic oligomers include acrylic or methacrylic esters of polyurethane, acrylic or methacrylic esters of polyether alcohol, acrylic or methacrylic esters of bisphenol A, and maleic or fumaric acid esters of polyester. Examples include esters.

In addition, examples of electron beam-curable polyfunctional acrylic monomers include 1,6-hexadiol diacrylate, neopentyl diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and pentaerythritol pentaacrylate. can be mentioned.

Furthermore, examples of electron beam-curable monofunctional acrylic monomers and vinyl monomers include styrene, N-vinylpyrrolidone, acrylic acid ester of polyoxyethylene phenyl alcohol, and 2-ethylhexyl acrylate.

In order to improve the sharpness of photographic images, it is preferable to incorporate a white inorganic pigment commonly used in photographic paper into the electron beam-curable resin coating layer of the present invention. Examples of such white inorganic pigments include titanium dioxide (anatase type and rutile type), barium sulfate, lucium carbonate, aluminum oxide, magnesium oxide, and the like. The average particle diameter of the white pigment used here is preferably in the range of 0.05 to 10 μm, particularly preferably 0.1 to 3 μm. In addition, the white pigment particles may be hydrated with metal oxides such as hydrated aluminum oxide, hydrated ferrite oxide, etc., or
The dispersibility can also be improved by treatment with organic compounds such as alcohols, amines, alkyl titanates, and organopolysiloxanes.

The amount of the inorganic white pigment in the electron beam curable resin coating layer is 15 to 80% by weight of the total solid weight of the electron beam curable resin coating layer.
It is preferable that If the amount is less than 15% by weight, the resulting photographic image on photographic paper may not have sufficient sharpness, and if it exceeds 80% by weight,
The flexibility of the resulting resin coating layer may decrease and cracks may occur.

The electron beam curing resin layer may further contain a blue pigment, an antistatic agent, a fluorescent whitening agent, etc., if necessary.

In the present invention, the electron beam curable resin composition applied onto the sheet-like substrate contains the above-mentioned components forming the composition.
A coating liquid is prepared by cross-dispersing the mixture using a mixer.

Mixing machines include 2-roll mill, 3-roll Minoboh Cowles Dissolver Homo mixer, and Sand Glider 1.
Alternatively, an ultrasonic disperser or the like can be used.

Further, the sheet-like substrate used in the present invention includes medium-quality paper, wood-free paper, and other paper base materials made of natural valves, synthetic valves, or mixtures thereof.

Further, as the sheet-like substrate, it is also possible to use a film or synthetic paper in which an inorganic white pigment is dispersed as required in a film base of polyolefins or polyesters.

Further, as a method for applying the inorganic white pigment-containing electron beam curable resin composition coating liquid onto a sheet-like substrate, for example,
Any conventional method such as a bar code method, an air doctor coating method, a plate coating method, a squeeze coating method, an air knife coating method, a reverse coating method, a transfer coating method, etc. may be used.

The amount of the electron beam cured resin coating layer is 6 to 60 g/m in solid content.
'', and its thickness is preferably in the range of 5 to 50. If the coating amount is less than 6 g/m', uneven coating may occur, and if it exceeds 60 g/ml, it may harden. requires a large amount of energy,
Problems such as insufficient curing may occur.

As the electron beam accelerator used for electron beam irradiation, for example, an electro-curtain beam method, a van de Graaff scanning method, or a double scanning method can be used, but the electro-curtain beam method is relatively inexpensive and can obtain high output. It is preferable to use The accelerating voltage during electron beam irradiation is preferably 100 to 300 kv, and the absorbed dose is 0.5 to 10 Mra.
It is preferable that it is d. When the accelerating voltage is 100 kV, the amount of energy transmitted is insufficient, and when it exceeds 300 kV, the energy efficiency used for polymerization decreases, making it uneconomical.

If the absorbed dose is less than 0.5 Mrad, the curing reaction will be insufficient, and if it exceeds 10 Mrad, the energy efficiency used in the curing reaction may decrease or the irradiated object may generate heat, which is not preferable.

Furthermore, the oxygen concentration in the atmosphere during electron beam irradiation is 1
．． (It is preferably less than looppm. If the oxygen concentration exceeds 1.000 ppm, oxygen acts as a retardant for the polymerization reaction, and the curing of the resin composition may become insufficient.

As described above, by providing an intermediate layer made of a polymer compound containing a radical scavenger between the sheet-like substrate and the electron beam-cured resin coating layer, conventional electronic The drawbacks of photographic paper having a line-cured resin coating layer can be overcome.

〔Example〕

The invention is further illustrated by the following examples. Of course, the present invention is not limited to the following examples.

Example 1 A support for photographic paper was prepared as follows.

■ Styrene-butadiene cobalt latex (manufactured by Japan Synthetic Rubber Co., Ltd., trademark: JSR-0545) for forming the intermediate layer! , :, 10,0
00 ppm hydroquinone was added and the mixture was stirred to prepare a coating solution for forming an intermediate layer.

Apply this coating liquid to a thickness of 75J! Im was coated on one side of a polyester film substrate using a bar coater so that the coating amount after drying was 5 g/m'', and dried to form an intermediate layer.

(2) Formation of electron beam curable resin coating layer Each component was blended according to the composition shown below, and this mixture was kneaded for 20 minutes using a colorless desolver to prepare a uniformly dispersed electron beam curable resin composition coating liquid.

Ingredients Epoxy acrylate (manufactured by Osaka Organic Chemical Co., Ltd., trademark: Visco-#540) Amount (parts by weight) 0 (manufactured by Nippon Kayaku Co., Ltd., trademark: )IDDA) Titanium dioxide
30 (manufactured by Ishihara Sangyo Co., Ltd., trademark: A-
220) This composition coating liquid was applied onto the intermediate layer using a bar coater so that the dry coating amount was 20 g/m'', and this coating liquid layer was coated with an electrocurtain type electron beam irradiation device (CB175/ 15/1g0L type (manufactured by ESI), electron beam irradiation was performed at an irradiation dose of 2 Mrad to harden the resin component to form a support for photographic paper.

The electron beam-cured resin coating layer of the photographic paper support was adhered to the emulsion surface of a commercially available color photographic paper and left for 3 days at a temperature of 65° C. and a relative humidity of 50%. This color photographic paper was peeled off from the resin coating layer, subjected to color development using an automatic processor (trademark: Model ATL-1, manufactured by JOBO), and the fog density was measured. The fog density of the developed photographic paper is measured using the Macbeth densitometer (trademark: Model NO, R[)-914, Kollm
Orgen Carp). The measurement results are shown in Table 1.

Example 2 The same operation as in Example 1 was performed. However, when forming the intermediate layer, the amount of hydroquinone contained was 5.000 ppm. The test results are shown in Table 1.

Example 3 The same operation as in Example 1 was performed. However, when forming the intermediate layer, the amount of hydroquinone contained was 1.000 ppm. The test results are shown in Table 1.

Comparative Example 1 The same operation as in Example 1 was performed. However, when forming the intermediate layer, the amount of hydroquinone contained was 500 ppm. The test results are shown in Table 1.

Comparative Example 2 The same operation as in Example 1 was performed. However, no radical scavenger was added when forming the intermediate layer.

The test results are shown in Table 1.

Comparative Example 3 The same operation as in Example 1 was performed. However, without forming an intermediate layer, an electron beam-cured resin coating was formed directly on a sheet-like substrate to form a support for photographic paper.

The test results are shown in Table 1.

Reference Example A resin coating layer made of a polyethylene resin composition containing 13% by weight of titanium dioxide was formed on one side of the same sheet-like substrate as in Example 1 to form a support for photographic paper. The test results are shown in Table 1.

As is clear from Table 1 below, the photographic paper obtained from the support of the present invention suppresses the occurrence of fading over time, which is known to be a problem specific to electron beam curing resins. be able to.

〔Effect of the invention〕

The support for photographic paper of the present invention is produced by providing an intermediate layer containing a polymer compound and a specific amount of a radical scavenger between the sheet-like substrate and the electron beam-curable resin coating layer. It is possible to suppress the fogging over time of photographic printing paper, which is known to be a problem specific to
Due to its excellent image resolution and sharpness, it is extremely useful in practice.

Claims (1)

[Scope of Claims] 1. A sheet-like substrate; an intermediate layer formed on at least one surface of the substrate and containing a polymer compound material and 1,000 to 10,000 ppm of a radical scavenger; A support for photographic paper, comprising a coating layer formed on the intermediate layer and containing an electron beam curing resin cured by electron beam irradiation.