JPS6067940A - Photographic printing paper support - Google Patents

Abstract

PURPOSE:To obtain a photographic printing paper good in smoothness by forming a paper layer having a specified void volume due to a specified pore diameter. CONSTITUTION:A paper layer to be used here has a void volume of >=0.04ml/g due to pore diameters of <=0.4mum measured by the Hg pressure injection method. The void of such pore diameters of <=0.4mum contributes to increase of flexibility of fibers, and the larger the void of <=0.4mum, the higher the effect, and satisfactory smoothness is obtained in the range of the void exceeding 0.04ml/g. In such paper, interlayers between thin layers on the inside of the fiber wall are loosened, and junction between each fiber has not grown, so the fibers collapse well to provide good smoothness. A photographic printing paper support having good surface smoothness is obtained by coating the surface of such paper with a PE resin or the like by the extrusion coating method, and it can be used for the support of color and black-and-white photographic printing papers, and a photocomposing paper, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photographic paper support having a smooth surface on which a light-sensitive emulsion is coated. More specifically, the present invention relates to a photographic paper support in which the paper layer coated with a thermoplastic resin is smoothed to thereby smooth the coated resin surface on which a photosensitive emulsion is applied.

Photographic paper manufactured by coating with thermoplastic resin differs from conventional photographic paper using baryta paper in that it has inferior heat resistance and lacks water vapor permeability of the support, making it difficult to use ferrotype printing. Print finishing is performed without For this reason, the smoothness of the finished photographic paper surface is largely controlled by the smoothness of the paper layer. Therefore, in order to obtain photographic paper with good smoothness, it is necessary to form a smooth paper layer.

The smoothness of the resin-coated photographic paper support (hereinafter referred to as 1. base paper) is measured by the JIS P-8119r paper and paperboard smoothness test method using a solidity tester. (, vertical direction of base paper (paper machine flow direction)
Refers to ripple-like unevenness parallel to the .

The smoothness of base paper varies depending on the type of pulp used as a raw material, pulp treatment, added chemicals, papermaking method, papermaking conditions, post-treatment, etc. Among these, the properties of the raw material pulp are particularly important. This is because, although the base paper is smoothed in the calendering step of the post-processing process, depending on the properties of the raw material pulp, smoothing may not proceed no matter how much the calendering process is strengthened.

According to the present invention, a smooth base paper can be obtained by forming a paper layer in which the amount of voids with a pore size of 0.4 μm or less measured by mercury porosimetry is 0.04 rtt/y or more.

In this mercury intrusion method, a sample is buried in a mercury reservoir, and pressure is applied to the mercury using ethanol, etc. as a medium, and the applied pressure and the amount of mercury that has penetrated into the sample (porous) (corresponds to the amount of voids in the sample). It is a measurement method that records the relationship between Here, assuming that the void in the sample is cylindrical, the radius of the cylinder (12 m)
The following relational expression (Kelvin's equation) is established between and the pressure (Ppa) applied to mercury, and the pore diameter can be determined from the pressure applied from the equation.

r (/'-) = 735.5 / P (Kpa
) Measurements were carried out using a Carlo Erba Model 1500 mercury porosimeter. For detailed measurement methods, see the Journal of the Paper and Pulp Technology Association (Part 3)
According to the method described in Vol. 3, No. 5, page 39).

The pores with a pore diameter of 0.4 μm or less mentioned in the claims correspond to the tail on the small pore diameter side from the peak position of the pore distribution. This point can be easily understood by looking at Figure 1. In FIG. 1, the curve marked with symbol (a) represents the void distribution in the base paper made from LBKP, and the curve marked with symbol (b) represents the void distribution in the base paper made from LBSP. The peak of this void volume distribution curve is caused by fiber gaps in the sheet, but the voids with a pore diameter of 0.4 μm or less, which is the problem in the present invention, are caused by unevenness on the fiber surface, especially voids near the bonding points between fibers, and fiber gaps in the sheet. It is responsible for the spaces between the lamina within the cell (not within the lumen).

In order to obtain smoothness of the base paper, when calendering is performed, the thin layer structure within the fiber cell walls must cause slippage between the thin layers and the fibers must be crushed well.

Here, according to the present invention, the amount of voids with a pore diameter of 0.4 μm or less is 0.04 d! If it is above /f, the thin layers within the fiber wall will be loose and the bonds between fibers will not develop, so the fiber will be good (
No crushing, good smoothness can be obtained.

By calendering, the amount of large voids between fibers corresponding to the main peak of the void amount distribution curve is reduced to a large lj, but the amount of voids is not significantly reduced in the void region of 0.4 μm or less, which is the target of the present invention. This is because voids of 0.4 μm or less contribute to increasing the flexibility of the fibers, and do not directly affect the apparent density of the paper layer (which is controlled by the amount of voids in the entire paper layer). That means no.

This effect becomes greater as the amount of voids of 0.4 μm or less increases, but as shown in FIG. 2, satisfactory smoothness can be obtained in a region exceeding 0.04 d/y. The scale on the vertical axis in FIG. 2 is the smoothness determined visually, and the grading was determined as follows.

Grade A Only extremely fine irregularities B Fine irregularities and extremely small ripples C Slightly noticeable ripples D Large ripples A grade of 8 or higher is a satisfactory level.

The photographic paper support of the present invention includes an antifoggant, a filler,
It contains additives normally used in paper making, such as dyes, sizing agents, paper strength enhancers, fixing agents, and retention improvers, as necessary. It is also possible to perform surface treatment with starch, polyvinyl alcohol, gelatin, etc., and antistatic treatment with sodium sulfate, sodium chloride, aluminum chloride, etc. on the base paper, if necessary.

Polyolefin resins include pomopolymers of α-olefins such as ethylene and propylene, copolymers consisting of two or more α-olefins such as ethylene and propylene, or α-olefins as a main component and other monomers copolymerizable with it. Preference is given to copolymers of and mixtures thereof. Furthermore, white pigments such as titanium oxide and alumina, colored pigments, and usually 4a (a stabilizer mixed with fat, an antioxidant, a dispersant, a lubricant, etc.) may be added to the resin.

The polyolefin resin-coated photographic paper support of the present invention is produced by a so-called extrusion coating method in which a heated and molten resin is cast onto a running base paper, and both sides of the support are coated with the resin.

Polyolefin resin coated photographic stamp jj of the present invention! ,ii
The paper support is used for color photographic paper, black and white photographic paper, typesetting photographic paper, copying photographic paper, and the like.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the Examples.

Example 1 LBSP was prepared from domestic hardwood chips under the following conditions.

(1) Cooking chemical solution: PH1.5 total acid 696 maximum temperature:
140℃ liquid ratio = 5 Total cooking time 26 hours Maximum temperature holding time: 2 hours 20 minutes (2) Bleaching Chlorine (abbreviation C) → Sodium hydroxide (abbreviation E) → Sodium hypochlorite (abbreviation H) → Dioxide Bleach in the order of chlorine (abbreviation D). The temperature, time, pulp concentration, and chemical addition rate for each stage are shown in Table 1.

Table 1 (3) Beating: Canadian standard Z water level (JISP
-8121-76) Beat for 350a+l.

(4) Paper making: paper width 500! 15 m/s on J Fourdrinier paper machine
/min, wet press: i≦-pressure 20$/”
This was done by passing it through the roll press twice.

The calender treatment was carried out once through a super calender with a linear pressure of 6 oν/1J14.

(5) Resin coating ffl: After corona treatment is performed on calendered paper, low density polyethylene containing 10% titanium oxide is coated on the surface and low density polyethylene is coated on the back to a thickness of 30 μm using an extrusion coating machine at a resin temperature of 330°C. A photographic paper support was obtained. This sample is designated as sample number 1.

Example 2 A photographic paper support was obtained in the same manner as in Example 1, except that the maximum temperature holding time during cooking was 2 hours and the chemical addition rate was 3% in the sodium hydroxide treatment stage of bleaching. This sample will be designated as sample number 2.

Comparative Example 1 A photographic paper support was obtained in the same manner as in Example 1, except that the maximum temperature holding time during cooking was 1 hour and 40 minutes, and the chemical addition rate was 3% in the sodium hydroxide treatment stage of bleaching. Ta. This sample will be designated as sample number 3.

Comparative Example 2: A photographic paper support was obtained in the same manner as in Example 1, except that commercially available LBKP (manufactured from domestic hardwood) was used as a group. This sample is designated as sample number 4.

The above results are summarized in Table 2.

As is clear from Table 2, the amount of voids of 0.4 μm or less is 0.
．． 04t/1! The photographic paper support made of the above base paper has good smoothness (visual grade).

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the pore diameter (logarithmic scale) of the pores in the base paper and the pore frequency. FIG. 2 is a graph showing the relationship between the amount of voids of 0.4 μm or less in the base paper and the visual smoothness grade of the photographic printing paper support. E L B K P void distribution row of base paper used as raw material
Void distribution of base paper used as LBSP raw material Figure 1 jog()L diameter)nom 2E

Claims (1)

[Claims] The amount of voids with a pore diameter of 0.4 μm or less measured by mercury intrusion method is 0.
．． 1. A photographic paper support, characterized in that it forms a paper layer having a paper layer of 0.04 tt/y or more.