EP0362823A2

EP0362823A2 - Paper for photographic purposes

Info

Publication number: EP0362823A2
Application number: EP89118412A
Authority: EP
Inventors: Mutsuo Akao; Koji Inoue
Original assignee: Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp
Priority date: 1988-10-04
Filing date: 1989-10-04
Publication date: 1990-04-11
Anticipated expiration: 2009-10-04
Also published as: EP0362823A3; EP0362823B1; DE68926770D1; DE68926770T2

Abstract

A paper for photographic containing a nonionic antifoamer of which the components do not include silicone nor propylene oxide, a paper for photograph containing a nonionic mineral oil antifoamer of which the components include silicone or silicone-modified silica and having a pH of 3.5 to 5.5 measured by the cool water extracting method, and a paper for photograph which contains a water-soluble aluminum salt and at least one of rosin sizing agent, polyacrylamide or polyamide-epoxy resin and has a pH of 3.5 to 6.0 measured by the cool water extracting method. In the above papers for photograph, silicone and propylene oxide which are harmful with respect to photographic properties are removed, or propylene oxide is removed and silicone is rendered harmless by adjusting the pH to an acidic range. Or, particular sizing agent and paper strongs agent less affecting photographic properties within a particular acidic range are selected.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to a paper for photograph, such as a packaging material for photographic photosensitive materials and a support for photographic paper.

Description of the Prior Art

In general, unbleached kraft papers including specialty papers such as unbleached Clupak paper and unbleached Duostress paper are inferior in photographic properties irrespective of the pH of the papers, for example neutral papers having a pH measured by the cool water extracting method (JIS P-8133) in the range of 6.5-9. Accordingly, unbleached kraft paper cannot be used in the portion to touch photographic photosensitive materials directly, and for example, it is used as the outer sheet of a double sheet bag shown in Japanese Patent KOKAI No. 62-53829. The photographic properties means the influence of a material upon a photographic material such as fogging, slippage in the sensitivity and decrease in the developed concentration, and good photographic properties affect a photographic material little.
On the other hand, it is known to wash with a great quantity of well water in the pulp washing process and the paper making process, to add a special additive (Japanese Patent KOKOKU NO. 58-43730) and to remove or stabilize harmful substances affecting photographic properties adversely.
However, the double sheet bag is expensive. Moreover, workability in a dark room is inferior, and the space between the outer sheet and the inner sheet is liable to be opened by hand instead of opening the inner sheet. In the case of the unbleached kraft paper improved by adding a special additive or the like, the photographic properties are not sufficiently improved. While, bleached kraft paper is excellent in photographic properties, and can be used as a single sheet bag. However, it is expensive, and physical strength such as surface strength is insufficient.

SUMMARY OF THE INVENTION

An object of the invention is to provide a paper for photographic excellent in photographic properties, in physical strength and inexpensive.
The present invention provides a paper for photograph which has achieved the above object, and based upon the studies with respect to the influences of various additives upon photographic properties.
The inventors investigated the influences of various additives added through the manufacturing process of unbleached kraft paper, and found that restricted antifoamers adversely affect the photographic properties. That is, in the manufacturing process of unbleached kraft paper, the antifoamer used in the washer process is a nonionic mineral oil of which the principal component is silicone, and the antifoamer used in the screening process and in the mixer process is a nonionic surfactant of which the principal component is propylene oxide. The inventors found that the silicone and propylene oxide remained in the kraft paper, and affected adversely the photographic properties. Moreover, the inventors found that, when the nonionic surfactant of which the principal component is propylene oxide was absent, the adverse affect of silicone could be eliminated by adjusting the pH (measured by the cool water extracting method) to 3.5 to 5.5.
Incidently, a sizing agent and a paper strongs agent are, in general, added in order to improve the surface strength and delamination resistance of a paper, and a water-soluble aluminum salt is further added in order to improve the retention of the sizing agent and the paper strongs agent. While, when the quantity of the water-soluble aluminum salt of was increased in order to make the improvement in the retention effectively, the manufactured paper was rendered acidic, and the photographic properties were worse. The inventors investigated the influences of various sizing agents and paper strongs agents, and found that restricted sizing agents and paper strongs agents do not adversely affect the photographic properties in acidic conditions, though they adversely affect in neutral conditions. That is, rosin sizing agents and paper strongs agents of polyacrylamides and polyamide-epoxy resins do not adversely affect photographic properties only in the range of pH 3.5 to 6.0.
Thus, the present invention provides a paper for photograph containing a nonionic antifoamer of which the components do not include silicone nor propylene oxide.
The present invention also provides a paper for photograph containing a nonionic mineral oil antifoamer of which the components include silicone or silicone-modified silica and having a pH of 3.5 to 5.5 measured by the cool water extracting method.
The present invention still also provides a paper for photograph which contains a water-soluble aluminum salt and at least one of rosin sizing agent, polyacrylamide or polyamide-epoxy resin and has a pH of 3.5 to 6.0 measured by the cool water extracting method.

DETAILED DESCRIPTION OF THE IVNENTON

The nonionic antifoamer, of which the components do not include silicone nor propylene oxide, includes mixtures of a nonionic surfactant and a fatty acid and/or a fatty acid compound such as a fatty acid amide, a fatty acid ester or a fatty acid metal salt, mixtures of a polyglycol and a fatty acid and/or a fatty acid compound such as a fatty acid amide, a fatty acid ester or a fatty acid metal salt, emulsifying pine oils, and nonionic fatty acids. Preferable nonionic antifoamers are mixtures of a nonionic surfactant and a fatty acid compound, and particularly preferred nonionic antifoamers contain a mixture of a nonionic surfactant and a fatty acid amide as the principal component. Polyoxyethylene sorbitan laurate is also particularly preferred. Preferable nonionic surfactants contain halides of hydrocarbon or a mixture thereof as the principal component.
The silicones harmfull for photographic properties are diorganopolysiloxane, polyoxyalkylene-modified polysiloxane, dimethylpolysiloxane, dimethyldichlorosilane, diethylpolysiloxane, methylphenylpolysiloxane, polydimethylpolydiphenylsiloxane copolymer, polymethyl-3,3,3-trifluoropropylsiloxane, polydimethylchloropropylmethylsiloxane and the like.
Propylene oxide also called 1,2-epoxypropane is reactive, and it is miscible with water, ethanol and the like. When propylene oxide is heated with alumina, it produces propionaldehyde which adversely affects photographic photosensitive materials.
A suitable quantity of the anti former is about 10 to 1500 g/pulp ton in the pulp washer process, about 5 to 600 g/pulp ton in the pulp screening process and less than 1 % per pulp weight in the mixer process.
In the above paper for photograph, since the antifoamer does not contain silicone nor propylene oxide which are the causes of sensitivity slippage and fogging, the photographic photosensitive materials are not adversely affected regardless of pH. This paper is inexpensive, and its physical strength is great.
The nonionic mineral oil antifoamer contains silicone or silicone-modified silica and a nonionic surfactant. The silicone may be selected from mentioned previously, and the silicone-modified silica is fine powder of silica treated with the silicone. Particularly preferred nonionic mineral oil antifoamer is polyoxyalkylene-modified polysiloxane blended with dimethylpolysiloxane, silica and a nonionic surfactant in view of excellent foam-extinguishing ability and foam-breaking ability.
A suitable quantity of the nonionic mineral oil antifoamer is about 100 to 1000 g(stock solution)/pulp ton. When the quantity is less than 100 g/pulp ton, foam-extinguishing effect is insufficient. While, when the quantity is beyond 1000 g/pulp ton, photographic properties are adversely affected.
In the above paper for photograph, the adverse affects of silicone and silicone-modified silica upon the photographic properties are reduced by adjusting the pH within the prescribed range, and necessary foam-extinguishing effects in the paper manufacturing process are secured by the silicone or silicone-modified silica.
When the nonionic mineral oil antifoamer is used, the pH measured by the cool water extracting method (JIS P-8133) is adjusted to 3.5 to 5.5. When the pH is lower than 3.5, the increase of sensitivity is great. While, when the pH is higher than 5.5, the increase of sensitivity is also great. The pH is adjusted by the quantity of additives such as aluminum sulfate. An acid, such as chloric acid, sulfuric acid, citric acid or oxalic acid, may be added, if necessary.
When the water-soluble aluminum salt and at least one of rosin sizing agent, polyacrylamide or polyamide-epoxy resin are used, the water-soluble aluminum salt is added for fixing the sizing agent and the paper strongs agent on the fiber of pulp. Examples of the water-soluble aluminum salt are aluminum sulfate, aluminum chloride, poly(aluminum chloride), poly(aluminum hydroxide), zinc chloride, stannous chloride and the like.
The quantity of the water-soluble aluminum salt is determined so that the pH measured by the cool water extracting method (JIS P-8133) of the paper for photograph becomes in the range of 3.5 to 6.0, and it is influenced by the pH of pulp, the quantity of various additives, the kind of the water-soluble aluminum salt and the like. An usual quantity of the water-soluble aluminum salt is about 0.5 to 10 wt. %, preferably 1 to 6 wt. %, of the dry weight of pulp.
The rosin sizing agents are divided into three groups of gum rosin, tall oil rosin and wood rosin. Maleic anhydride or fumaric anhydride is added to the rosin by heating to produce maleinzed rosin or fumaric-induced rosin, and an alkali is added to obtain a solution of fortified rosin sizing agent. While, the maleinized rosin or fumaric-induced rosin is suspended in water with an emulsifier to obtain an emulsion-type rosin sizing agent.
Polyacrylamide acts a paper strongs agent, and exhibit additional effects such as the improvement in the fixation of fillers and fine fibers and the improvement in drainage ability. In order to improve the fixation to pulp, a part of amide groups are changed to carboxyl groups. The carboxyl group-induced polyacrylamide is fixed on the fiber of pulp through aluminum sulfate. A suitable modification rate of polyacrylamide is that about 10 % of amide groups are changed to carboxyl groups.
Polyamide-epoxy resin is used as an non-formaldehyde resin, and it exhibits a high ability as a wet paper strongs agent.
The quantity of the rosin sizing agent, polyacrylamide and polyamide-epoxy resin is about 0.05 to 10 wt. %, preferably 0.2 to 5 wt. % of the dry weight of pulp.
The pH measured by the cool water extracting method (JIS P-8133) is 3.5 to 6.0. When the pH is lower than 3.5, the increase of sensitivity is great. While, when the pH is higher than 6.0, the increase of sensitivity is also great. The pH is adjusted by the quantity of additives such as aluminum sulfate. An acid, such as chloric acid, sulfuric acid or oxalic acid, may be added, if necessary.
In the above paper for photograph, the water-soluble aluminum salt improves the retention of the sizing agent and the paper strongs agent, and adjust the pH within the range of 3.5 to 6.0. The rosin sizing agent, polyacrylamide and polyamide-epoxy resin improves the surface strength. The adjustment of the pH within the range of 3.5 to 6.0 renders the rosin sizing agent and the like harmless for the photographic properties.
The paper for photograph of the invention is used for packaging materials for photographic photosensitive materials, light-shielding paper, support for photograph, pad, carton box, core, guard sheet, leader paper, materials for composing instant photograph. A preferable use of the paper of the invention is the inner surface layer of the laminated film formed in a single sheet bag to touch the emulsion face of the photosensitive materials.

EXAMPLES

Example I

A nonionic antifoamer containing a fatty amide and silicone as the principal components ("PRONAL K-302N", Toho Chemical Industries) was made water-soluble by removing silicone. An unbleached kraft pulp was prepared wherein 500 g/pulp ton of the above nonionic antifoamer was added in the pulp washer process and 200 g/pulp ton of the same antifoamer was further added in the pulp screening process of the pulp washing process. The unbleached kraft pulp was beaten up to a CPPA standards drainage rate of 450 ml to produce a pulp slurry. To the pulp slurry was added polyacrylamide in an amount of 1.0 wt. % of the pulp and aluminum sulfate in an amount of 3.0 wt. % of the pulp. A handmade paper of pH 4.5 having an areal weight of 70 g/m² was prepared from the above paper stock by using a TAPPI type handmaking machine.

Example II

This paper was the same as the product of the invention I, except that the amount of aluminum sulfate was 0.3 wt. % of the pulp and the pH was made 7.2.

Comparative Example I

An unbleached kraft paper of pit 4.3 was prepared in the same manner as the product of the invention I, except that 500 g/pulp ton of the nonionic antifoamer ("PRONAL K-302N") without the water-solubilization treatement was added in the pulp washer process of the pulp washing process instead of the water-soluble anti former obtained from "PRONAL K-302N" and 200 g/pulp ton of a nonionic antifoamer containing propylene oxide and ethylene oxide as the principal components ("PRONAL S-121", Toho Chemical Industries) was added in the process instead of 200 g/pulp ton of the water-soluble antifoamer.

Comparative Example II

An unbleached kraft paper of pH 7.0 was prepared in the same manner as Comparative Example 1 before and in the pulp washer process, and in the same manner as Example II after the pulp washer process.

The photographic properties and surface strength of the above products were measured, and the results are summarized in Table 1.

Table 1

	Invention		Comparative
	I	II	I	II
pH of Paper	4.5	7.2	4.3	7.0
	Acidic	Neutral	Acidic	Neutral

Photographic Properties (Contact)
Slippage in Sensitivity of Green Coloring Layer	0	0	+0.02	+0.02
Slippage in Sensitivity of Blue Coloring Layer	+0.01	0	+0.04	+0.04
Slippage in Sensitivity of Red Coloring Layer	0	0	+0.03	+0.03
Surface Strength (Wax No.)	12A	10A	12A	10A

Test Method:

pH of Paper:

Measured by the cool water extracting method according to JIS P-8133

Photographic Properties (Contact):

The emulsion face of a color photographic printing paper was contacted with the handmade paper, and kept at 50°C for 3 days without humidity conditioning. Then, each photographic printing paper was developed by a conventional manner, and each color concentration was measured by using a densitometer ("Fuji Densitometer", Fuji Photo Film). Each numerical value in the table is the difference from the case of the paper not added with the reagent.

Surface Strength:

Measured according to JIS wax method of JIS P-8129

Example III

500 g/pulp ton of a nonionic antifoamer ("PRONAL K-302N", Toho Chemical Industries) was added to an unbleached kraft pulp, and the unbleached kraft pulp was beaten up to a CPPA standards drainage rate of 450 ml. The pH measured by the cool water extracting method (JIS P-8133) of the beaten pulp was adjusted to 4.5 by adding aluminum sulfate. A handmade unbleached kraft paper having an areal weight of 70 g/m² was prepared from the above paper stock by using a TAPPI type handmaking machine.

Comparative Example III

An unbleached kraft paper prepared in the same manner as the product of the invention III, except that the pH of the beaten pulp was adjusted to 7.0 by adding aluminum sulfate.

The photographic properties of the above products were measured, and the results are shown in Table 2.

Table 2

	Invention III	Comparative III
pH of Paper	4.5	7.0

Photographic Properties (Contact)
Slippage in Sensitivity of Blue Coloring Layer	+0.01	+0.05
Slippage in Sensitivity of Green Coloring Layer	0	+0.03
Slippage in Sensitivity of Red Coloring Layer	0	+0.02

Photographic Properties (Gas)
Slippage in Sensitivity of Blue Coloring Layer	0	+0.02
Slippage in Sensitivity of Green Coloring Layer	+0.01	+0.02
Slippage in Sensitivity of Red Coloring Layer	0	+0.01

Test Method:

Photographic Properties (Gas):

The emulsion face of a color photographic printing paper was faced to the handmade paper through a perforated sheet, and kept at 50°C for 3 days without humidity conditioning. Then, each photographic printing paper was developed by a conventional manner, and each color concentration was measured by using a densitometer ("Fuji Densitometer", Fuji Photo Film). Each numerical value in the table is the difference from the case of he paper not added with the reagent.

Example IV

An unbleached kraft pulp was beaten up to a CPPA standards drainage rate of 450 ml by a mill, and to the beaten pulp was added 0.3 wt. % of a rosin sizing agent (fortified rosin sizing agent), 2 wt. % of anionic polyacrylamide as the paper strongs agent and 3 wt. % of aluminum sulfate as the water-soluble aluminum salt. A handmade paper of pH 4.5 (measured by the cool water extracting method of JIS P-8133) having an areal weight of 70 g/m² was prepared from the above paper stock by using a TAPPI type handmaking machine.

Comparative Example IV

This paper was a handmade paper of pH 7 measured by the cool water extracting method prepared in the same manner as the product of the invention IV, except that the amount of aluminum sulfate was changed to 1.5 wt. %.

Comparative Example V

A handmade paper of pH 7 measured by the cool water extracting method was prepared in the same manner as the product of the invention IV, except that the amount of aluminum sulfate was changed to 1.5 wt. % and that polyacrylamide was not added.

Comparative Example VI

A handmade paper of pH 4.5 measured by the cool water extracting method was prepared in the same manner as the product of the invention IV, except that 2 wt. % of melamine resin was added instead of polyacrylamide.

Example V

A handmade paper of pH 4.7 (measured by the cool water extracting method) having an areal weight of 70 g/m² was prepared in the same manner as the product of the invention IV, except that no rosin-sizing agent was added.

Comparative Example VII

A handmade paper of pH 4.6 (measured by the cool water extracting method) was prepared in the same manner as the product of the invention V, except that 2 wt. % of modified starch ("PEPARIN", Matsutani Chemical Co., Ltd.) was used instead of polyacrylamide.

The photographic properties of the above products were measured, and the results are shown in Table 3.

Table 3

	Invention	Comparativ e			Invention	Comparative
	IV	IV	V	VI	V	VIII
pH of Paper	4.5	7.0	7.0	4.5	4.7	4.6

Photographic Properties (Contact)
Slippage in Sensitivity of Green Coloring Layer	+0.01	+0.08	+0.04	+0.05	+0.01	+0.03
Slippage in Sensitivity of Blue Coloring Layer	0	+0.06	+0.05	+0.07	+0.02	+0.03
Slippage in Sensitivity of Red Coloring Layer	+0.01	+0.03	+0.02	+0.06	+0.01	+0.07

Claims

1. A paper for photographic containing a nonionic antifoamer of which the components do not include silicone nor propylene oxide.

2. The paper of claim 1 wherein the nonionic antifoamer is a member selected from the group consisting of mixtures of a nonionic surfactant and a fatty acid and/or a fatty acid compound, mixtures of a polyglycol and a fatty acid and/or a fatty acid compound, emulsifying pine oils, and nonionic fatty acids.

3. A paper for photograph containing a nonionic mineral oil antifoamer of which the components include silicone or silicone-modified silica and having a pH of 3.5 to 5.5 measured by the cool water extracting method.

4. A paper for photograph which contains a water-soluble aluminum salt and at least one of rosin sizing agent, polyacrylamide or polyamide-epoxy resin and has a pH of 3.5 to 6.0 measured by the cool water extracting method.