JPH02308242A - Base for photographic paper - Google Patents

Abstract

PURPOSE:To obtain the base for photographic paper having good surface smoothness by using pulp fibers having a specific weight average fiber length and water retention value as raw paper. CONSTITUTION:The combination paper to be used as the raw paper is formed by combination of multiple layers (2 to 5 layers) and is particularly preferably the combination of 2 to 3 layers. The production of such combination paper is executed by circular wire cloth sheeting or long wire cloth sheeting. Various kinds of the natural pulp obtd. from needle-leaved trees, broad-leaved trees, etc., and synthetic pulp are used for the pulp. Of these kinds of the pulp, the pulp having the weight average fiber length measured by a fiber length analyzer of a polarized light transmission system within a 0.4 to 0.9mm, more preferably 0.45 to 0.6mm range is particularly used. The pulp fibers having the water retention value within a 120 to 190%, more preferably 140 to 170% range are used. The surface of the raw paper produced by the combination method using the above-mentioned pulp fibers is coated with polyolefin, by which the base for photographic paper is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a support for photographic paper, and particularly to a support for photographic paper that has a good surface smoothness.

(Prior Art) Currently, photographs with smooth and glossy surfaces are generally preferred.

In this case, the thickness of the photographic emulsion layer is 10. There is a need for a support for photographic paper that has a smooth surface because it is extremely thin, around czm, and the smoothness of the surface of the photographic paper is almost the same as the smoothness of the surface of the support underneath.

In order to obtain a photographic paper support with a smooth surface, it is desirable that the base paper constituting it is smooth.

Particularly in the case of photographic paper that is printed without ferrotyping, even if the surface of the base paper is coated with polyolefin and a photographic emulsion layer is formed on top of it, it is still possible to create a coating layer that is cost-effective. It is difficult to hide the unevenness of the base paper from the support surface within the thickness range, and the smoothness of the support surface depends on the smoothness of the base paper, so it is said that it is essential that the base paper be smooth.

Therefore, various proposals have been made to improve the surface smoothness of the base paper used as a support for photographic paper. 4 m+ to 0.9 m, and the number average fiber width measured with a microscope is 13.5 μm or more,
A support for photographic paper (Japanese Patent Laid-Open No. 60-69649) has been proposed using a base paper made of pulp fibers having a number average fiber thickness of 4 μm or less as measured in the cross section of the fibers.

(Problem to be Solved by the Invention) However, simply limiting the range of pulp fibers to the above-mentioned specific range does not necessarily result in a smooth base paper, and the use of such fine fibers is difficult to obtain due to paper strength. This method has the drawback that it not only has a low value but is also disadvantageous in terms of cost.

In addition, specifying the number average fiber width and number average fiber thickness described in the above-mentioned Japanese Patent Application Laid-Open No. 60-69649 requires a lot of effort and time for measurement and subsequent statistical calculation processing. The disadvantage is that it is complicated. or,
The above factors are said to be unsuitable as values for limiting the range of pulp fibers, as they swell and change over time from the time of pulp slurry preparation, and are inappropriate as control factors during base paper production. There are drawbacks.

Such disadvantages arise when using a method using a base paper produced by a paper-combining method (JP-A No. 63-204250) or when the weight average fiber length is in the range of 0.4 to 0.9 m and the water retention is 1.
This was improved by using a base paper containing pulp fibers in the range of 20% to 190% (Japanese Patent Application Laid-open No. 59350/1983).

However, there are limits to the improvements made by these methods, and they are still unsatisfactory.

As a result of intensive studies from this point of view, the present inventors found that at least the upper layer of the laminated paper has a weight average fiber length of 0.4W to
It is in the range of 0.9 am and the water retention degree is 120% to 190
The inventors have discovered that very good results can be obtained by using pulp fibers in the range of % to 100%.

Therefore, the first object of the present invention is to efficiently produce a base paper with excellent surface smoothness that can be suitably used as a support for photographic paper.
It is about providing.

A second object of the present invention is to provide a support for photographic paper that has a smooth surface without the need for ferrotyping.

(Means for Solving the Problems) The above-mentioned object of the present invention is to provide a support for photographic paper in which the surface of a base paper produced by a sheeting method is coated with polyolefin, which comprises The weight average fiber length measured with a polarized light transmission type fiber length analyzer is 0.
It is in the range of 4u ~ 0.9mm and has a water retention degree of 120
% to 190%.

In the present invention, the laminated paper used as the base paper is a laminated paper made by laminating multiple layers (2 to 5 layers), especially 2 to 3 layers.
Preferably, the layers are combined.

These laminated papers are manufactured by cylinder paper making or fourdrinier paper making.

As the pulp, various natural pulps and synthetic pulps obtained from coniferous trees, hardwoods, etc. are used.

The furnace water degree of the pulp is 150 to 400 d, preferably 200 to 350 d.

In the present invention, among these pulps, in particular, pulps with a weight average fiber length of 0.4 mm as measured by a polarized light transmission type fiber length analyzer are used.
A pulp in the range ~0.9mm, preferably 0.45an to 0.6am is used.

The method for measuring the fiber length and the method for calculating the weight average fiber length are performed according to the method described in JP-A-60-69649. In this measurement, the amount of liquid containing approximately 0.00111% of pulp fibers is 50d~100%.
A sample solution of mff1 is used.

If the weight average fiber length is less than 0.4ffII11, the strength of the base paper will drop significantly and the base paper will easily tear in the post-papermaking process, and if it exceeds 0.9mm, it will not have good formation. However, when the base paper is dried, significant shrinkage occurs, and the protrusions are difficult to collapse even after calendering, making it impossible to obtain a base paper with excellent smoothness, making it impossible to achieve the object of the present invention.

Further, in the present invention, pulp fibers having a water retention degree of 120% to 190%, preferably 140% to 170% are used.

This water retention rate is determined by suction-filtering the beaten pulp suspension through a suitable filtration container called a centrifugal cup, placing the entire container into the sedimentation tube of a centrifuge, centrifuging it under certain conditions for a certain period of time, and dehydrating it. Take out the pulp and weigh it, then 10
If the sample weight after centrifugation is A and the weight after absolute drying is B when the absolute dry weight is determined by drying at 5°C, it is expressed as follows.

If the water retention is less than 120%, the strength of the paper layer will be weak, causing problems such as paper breakage and wrinkles during the manufacturing process, and if the water retention is more than 190%, paper manufacturing A problem arises in that the base paper shrinks in the drying zone of the process and wrinkle-like unevenness occurs, and in either case, it is impossible to obtain a base paper with excellent smoothness without causing poor appearance.

This pulp also contains clay, talc, calcium carbonate,
Fillers such as titanium oxide and urea resin particles, rosin, alkyl ketene dimer, higher fatty acid salts, paraffin wax, sizing agents such as alkenyl succinic acid, paper strength agents such as polyacrylamide, melamine resin, polyamide polyamine epichlorohydrin resin, and sulfuric acid bands. , a fixing agent such as a cationic polymer can be added as necessary.

Furthermore, the surface of the pulp can be subjected to surface size treatment with a film-forming polymer such as gelatin, starch, carboxymethyl cellulose, polyacrylamide, polyvinyl alcohol, or a modified product of polyvinyl alcohol.

Examples of polyvinyl alcohol modified products in this case include carboxyl modified products, silanol modified products, and copolymers with acrylamide. In addition, when surface size treatment is performed using a film-forming polymer, the coating amount of the film-forming polymer is 0.1 to 5.0 g/rrf, preferably 0.5 to 3°0.
g/%. Furthermore, the film-forming polymer at this time may contain antistatic agents, optical brighteners, pigments,
Antifoaming agents and the like can be added.

The base paper used for the photographic support of the present invention is usually composed of the above-mentioned pulp, additives, surface treatment agents, etc., and has a basis weight of 80 g/rrf to 200 g/rrf and a thickness of 80 μm to 200 g/rrf.
Adjusted to 230μ.

For the polyolefin resin coating layer laminated on both sides of the base paper, a polyethylene layer having a thickness of 15 to 40 μ, for example, can be used. The polyolefin resin film layer on the surface on which the photographic emulsion layer is formed contains 5% to 20% by weight of titanium oxide.

Examples of the above-mentioned polyolefins include homopolymers of α-olefins such as polyethylene and polypropylene, and mixtures of these various polymers. Particularly preferred polyolefins are high density polyethylene, low density polyethylene and mixtures thereof. These polyolefins are usually coated on both sides of the base paper by an extrusion coating method, and therefore there is no particular restriction on their molecular weight as long as they can be extrusion coated, but polyolefins usually have a molecular weight in the range of 104 to 106. is used.

The thickness of the polyolefin coating layer is not particularly limited and can be determined according to the thickness of the polyolefin coating layer of conventional photographic paper supports, but is usually preferably 10 to 50 .mu.m.

It is preferable that the polyolefin coating layer on the front side, that is, the side to which the photographic emulsion is coated, contains a white pigment.
The type, amount, etc. of this white pigment can be appropriately selected from known ones. Furthermore, optical brighteners,
It is also possible to add known additives such as antioxidants.

Further, the polyolefin coating layer on the back side can be composed only of the polyolefin resin, but it can also be composed of colored pigments,
A white pigment or the like may be added, and the same additives as those for the polyolefin coating layer on the front surface may also be added.

Incidentally, as the extrusion coating equipment for extrusion coating polyolefin, a usual polyolefin extruder and laminator are used.

(Effects of the Invention) According to the present invention, since the base paper for the support for photographic paper is manufactured by a paper-combining method, a base paper with high smoothness can be obtained in relation to its basis weight, and the fiber length can be within a specific range. Since pulp fibers having high water retention are used, base paper with excellent surface smoothness can be reliably obtained.

Therefore, by using this, a support for photographic paper with good front surface smoothness can be obtained at low cost.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Examples 1 to 4 and Comparative Examples 1 to 6] Wood pulp of the types and mixing ratios shown in Table 1 was refined using a disc refiner so that the weight average fiber length and water retention were as shown in the table. Beaten.

Incidentally, the weight average fiber length is determined as described in JP-A No. 60-69649 using a diluted solution of 50 to 100 d with a pulp fiber concentration of 0.001% by weight obtained by diluting the above-mentioned pulp fiber mixture. The water retention degree was measured and calculated according to the method described in this specification.

Table 2 shows the results of smoothness evaluation on both sides of photographic paper produced using two layers of base paper made from the obtained beaten sample, along with the basis weights of the upper and lower layers of the base paper and the total basis weight. Ta.

The photographic paper was produced as follows.

Using pulp fibers having the above weight average fiber length and water retention, add 1,000 ml of sodium stearate to the pulp in an absolutely dry state.
A sample was prepared by adding 5% by weight, 1.5% by weight of polyacrylamide, 0.3% by weight of polyamide polyamine evichlorohydrin, and 1.5% by weight of band sulfate. Using these samples, paper with a weight of 170 g/bo and a thickness of 160 μm was made using a long-length paper machine. The surface size in the size press is 1 based on the amount of polyvinyl alcohol deposited.

Og/I was applied.

Next, using a laminator, the front surface was laminated with polyethylene containing 10% by weight of titanium oxide, and the back surface was laminated with 28 μm of polyethylene alone, and the surface of the polyethylene containing titanium oxide of the support was subjected to corona discharge treatment. A silver halide gelatin emulsion for yellow color photography, a gelatin intermediate layer, a magenta color emulsion, a gelatin intermediate layer, a cyan color emulsion, and a gelatin protective layer were coated in order from the bottom and dried to prepare color photographic paper. These were exposed to gold light and developed using an automatic processor to obtain test samples.

The smoothness of both sides of the photographic paper was visually checked and compared and judged according to the following criteria.

Smoothness class A: Extremely smooth with no visible wrinkles.

Smoothness class B: Almost no wrinkle-like unevenness is observed, and the smoothness is good.

Smoothness class CAL, some ridges and convexities are observed, and the smoothness is poor.

Smoothness class D = poor smoothness with many wrinkle-like irregularities.

Table 2 [Examples 5 to 8 and Comparative Examples 7 to 13] Photographic paper was produced in the same manner as in Example 1 using a base paper prepared by combining three layers of the beaten samples shown in Table 1. The results of evaluating the screen smoothness of the obtained photographic paper are shown in Table 3 together with the basis weights of the upper, middle and lower layers of the base paper and the total basis weight.

As is clear from the above results, it was demonstrated that the photographic paper of the present invention is of extremely high quality.

Claims (1)

[Claims] A support for photographic paper in which the surface of a base paper is coated with a polyolefin produced by a papermaking method, and the weight average fiber length of the pulp fibers used in the base paper is 0. A support for photographic paper, characterized in that it has a thickness in the range of 4 mm to 0.9 mm and a water retention degree in the range of 120% to 190%.