JPS5942295B2 - Water-resistant photographic paper support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-resistant photographic paper support having a smooth surface on which a light-sensitive emulsion is coated.

More specifically, the present invention relates to a support for water-resistant photographic paper that smoothes the surface of the coated resin on which a photosensitive emulsion is applied by smoothing the paper layer coated with a thermoplastic resin.

Water-resistant photographic paper manufactured by coating with thermoplastic resin, unlike photographic paper using conventional baryta paper, has poor heat resistance and lacks water vapor permeability of the support, making it difficult to use ferrotype printing. Print finishing is performed without In addition, recent photosensitive emulsion coating methods use an extrusion coating method, so if the surface of the photographic paper support is not smooth, the photosensitive emulsion may be coated due to minute fluctuations in the clearance between the support surface and the extrusion coater head. Causes uneven coating.

The smoothness of the resin-coated water-resistant photographic paper support referred to here is not measured by JISP-8119 "Beck test for paper and paperboard, smoothness test method using test equipment", but is measured by the drying of pulp fibers. Refers to the ripple-like unevenness caused by contraction. For these reasons, the resin-coated water-resistant photographic paper support is required to have a smooth surface.

Although the smoothness of the resin-coated paper surface varies depending on the conditions during the resin-coating process, it is mostly determined by the surface properties of the resin-coated base paper.

The surface smoothness of the base paper for resin coating varies depending on the type of pulp used as a raw material, pulp treatment, added chemicals, papermaking method, papermaking conditions, post-treatment, etc.

Conventionally, the smoothness of resin-coated paper base paper has been imparted by calendering or supercalendering, which is a post-treatment.

The supercalender treatment is an off-machine process, which increases the number of steps, and has disadvantages such as a reduction in the effectiveness of the anchor coating agent applied to the base paper for resin coating.

The present inventors have taken the above-mentioned matters into account and have completed a resin waterproof support for photographic paper that has a smooth surface without any treatment such as supercalendering.

That is, the present invention provides a support for water-resistant photographic paper in which both sides of a paper layer are coated with a thermoplastic resin, in which the paper layer is made of pulp with a light scattering coefficient of 350 to 550 Clij/9. This invention relates to paper supports. The support obtained by the present invention has particularly high smoothness. The pulp used in the present invention has a light scattering coefficient of 350 to 5.
50cli//9.

Further, the pulp used in the present invention is NBSP, LBSP.
, LBKP, or a mixture of two or three. Note that there is no problem in adding other pulps such as NBKP to the above pulp or pulp mixture. The light scattering coefficient is measured by the following method. The pulp used is beaten according to the method using a heater in JISP-8210 "Method for testing the strength of pulp for papermaking", and is beaten according to the method using a heater in JISP-8210 "Method for testing the strength of pulp for pulp".
It is beaten to 300m1 according to the Canadian standard form of JISP.
Ten sheets of 80 f1/M2 hand-made paper are prepared using a hand-sheeting machine according to 8209 [Method for preparing hand-sheeted paper for pulp testing], water is squeezed out using a hand press, and dried at 1100C using a drum dryer. This handmade paper is JISP
-8111 "Pre-treatment of test paper", and according to JISP-8138 "Paper opacity test method", one sheet of the handmade paper was placed on top of the black backing board.
The reflectance of each sheet was measured, and the average value was R.

shall be. Next, 10 sheets of this handmade paper were stacked without using a backing black plate and the reflectance was measured.

Let it be O. The handmade paper used for this measurement was dried at 105℃ for 3 hours using an oven dryer, and
124 "Method for Measuring Paper Metric Basis Weight", the absolute dry basis weight is measured. This is defined as W (9/M2).

This R.

, ROO, and W to find the light scattering coefficient (?/9) using the following equation. As a general property of pulp, the light scattering coefficient exhibits a higher value as pulp is more advanced in digestion.

In addition, it decreases as the beating progresses. This is Taberka (Ku
This is clear from the theories of Belka and Munk.

The present inventors believe that the reason why pulp with a high light scattering coefficient provides high smoothness is as follows.

According to the theory of Kubelka and Munk, the light scattering coefficient represents the amount (energy) of light scattered inside the paper layer, and a large amount of scattered light means that there is an optical boundary. indicates that there are many That is, it shows that the adhesion area between pulp fibers is small. The smaller the bonding area between the fibers, the less shrinkage in the dryer due to drying of the wet paper, which causes damage to the smoothness of the paper surface.

Therefore, when pulp with a high light scattering coefficient is used, the adhesive area between fibers is small, shrinkage in the dryer can be reduced, and the smoothness of the surface of the base paper can be improved.

The thermoplastic resin used in the present invention is not particularly limited, but polyolefin resins such as polyethylene are particularly preferred. The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the Examples.
Example 1 NBSP, LB having the light scattering coefficient shown in Table 1
The surface smoothness of base paper made using SP and LBKP, base paper made using NBKP as a comparative product, and four types of resin-coated paper obtained by coating the above four types of base paper with resin is shown in the table below. It is as follows.

In addition, as mentioned above, the light scattering coefficient of pulp is 300 m1
The measurement was carried out by beating to 0 water level (Canadian standard type), but the water level at the time of making the base paper was set to 250 m1 as shown below.

The production of base paper using the above pulp and the anchor coating on the base paper were performed under the following conditions and method.

(1) Beating machine: Double disk cliff Aina - Beating degree: 2
50ml (2) Additive chemicals (added amount is absolute dry weight % based on the pulp) (3) Adjust pH to 6.8 with caustic soda Paper machine Width 500m 71L Fourdrinier paper machine This is a processing substitute for a machine calender.

The thermoplastic resin was coated on the base paper under the following conditions.

Anatase type titanium oxide is added to the above low density polyethylene.
The surface smoothness of the master base paper and resin-coated paper obtained by containing 0 parts by weight was graded with the naked eye as follows.

As is clear from Table 1, the surface smoothness of the base paper and resin-coated paper made using pulp with a high light scattering coefficient is good.

Example 2 Table 2 shows the surface smoothness of a base paper made using a pulp mixture having a light scattering coefficient shown in Table 2 and a resin-coated paper obtained by coating the base paper with a resin.

The pipes were prepared by mixing separately beaten products.

The conditions and method for making the base paper, anchor coating the base paper, and coating the base paper with a thermoplastic resin were exactly the same as in Example 1.

Claims (1)

[Claims] 1 In a water-resistant photographic paper support formed by coating both sides of a paper layer with a thermoplastic resin, the paper layer has a light scattering coefficient of 350 to 5.
A water-resistant support for photographic paper, characterized in that it is made of pulp of 50 cm^2/g.