JPH0648357B2 - Support for photographic paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photographic paper support having a smooth surface coated with a photosensitive emulsion. More specifically, it relates to a support for photographic printing paper, which smoothes the surface of a coating resin coated with a photosensitive emulsion by smoothing a paper layer coated with a thermoplastic resin.

The photographic printing paper coated with a thermoplastic resin is different from the printing paper using conventional baryta paper in that it is inferior in heat resistance and lacks water vapor permeability of the support. The print finish is done without. Therefore, the smoothness of the surface of the finished printing paper is considerably controlled by the smoothness of the paper layer. Therefore, it is necessary to form a smooth paper layer in order to obtain a photographic printing paper having good smoothness.

The smoothness of the resin-coated photographic printing paper support (hereinafter abbreviated as “base paper”) as used herein is not measured by JIS P-8119 “Smoothness test method for paper and board by Beck tester” or the like. , Rippling irregularities with regularity parallel to the longitudinal direction of the base paper (machine direction also in the paper machine). The visual smoothness of photographic printing papers is dominated by the degree of regular wavy irregularities, and does not directly depend on the degree of irregular irregularities measured by a Beck tester. The smoothness of the base paper changes depending on the type of pulp as a raw material, the treatment of pulp, the added chemicals, the paper-making method, the post-treatment of paper-making conditions, and the like. Of these, the properties of the raw pulp are particularly important. This is because the base paper is smoothed in the calender in the post-treatment step, but depending on the properties of the raw material pulp, the smoothing may not proceed even if the calender treatment is strengthened.

The object of the present invention is not the smoothness due to the degree of irregular asperity measured by a Beck smoothness tester, but the degree of irregular ripples having regularity parallel to the longitudinal direction of the base paper (flow direction of the paper machine). To improve the visual smoothness of the photographic paper support which is dependent on

According to the present invention, the weight average fiber length measured by a polarization transmission fiber length analyzer is in the range of 0.4 mm to 0.9 mm,
By forming a paper layer from pulp fibers having a number average fiber width measured by a microscope of 13.5 μm or more and a number average fiber wall thickness of 4 μm or less, the smooth base paper without ripples and irregularities can be obtained.

Next, in the fiber length distribution measured by the above method, one of the fiber lengths
A smoother base paper can be obtained by forming a paper layer from pulp fibers having a cumulative weight fraction up to mm of 68%.

Further, when the paper layer is formed of pulp fibers having a felting power of 56 or less, which is the ratio of the weight average fiber length to the number average fiber width, measured by the above-mentioned measuring method, an even smoother base paper can be obtained.

The polarization transmission type fiber length analyzer mentioned here is a device developed by Kajaani, Finland to automatically measure the fiber length distribution.

The principle of this device will be described with reference to FIG. A pulp slurry of very low concentration is made, passed through a thin capillary tube 4, and sucked by a vacuum pump 9. The fibers 5 are stretched in the thin capillary tube 4 and become straight. Here, the light emitted from the light source 1 is collimated by the incident optical system 2, and the collimated light is passed through the incident polarization filter 3 and applied to the capillary tube 4 (polarized light parallel to the capillary tube). The light that has passed through the fiber-free portion of the capillary 4 has a detection polarization filter 6 (having a polarization plane in a direction perpendicular to the capillary 4).
Will be cut off by. However, since the light passing through the fiber 5 has a changed polarization angle, it can pass through the detection polarizing plate 6.
This light is expanded by the optical system 7 and converted into fiber length data by the detecting element 8. (For details, refer to Japanese Patent Application No. 57-146969.) The measurement was carried out by an FS-100 model manufactured by Kajaani.

On the other hand, in terms of physical properties, the weight distribution is more important than the number distribution of the fiber length. Here, since the width of the fiber is roughly proportional to the fiber length, the cumulative weight fraction [W%] up to a certain length lk
Can be expressed by the following equation.

(Here, the measurable length is divided into n equal parts, and the median value of the i-th section is defined as li. Lk represents the median value of the k-th section. Ni is the fiber of the i-th section. The total weight average fiber length Lw is defined by the following equation.

This weight average fiber length has been conventionally measured by a sieving method or the like (TAPPI, Standard T-2).
33 OS-75), it has high detection power. Further, with this method, the fiber length can be measured without being affected by the width of the fiber, the thickness of the fiber wall, the flexibility of the fiber, and the like. However, fiber width and fiber wall thickness must be measured from micrographs. When taking a micrograph, a fiber sample in a disintegrated state is used for the fiber width, but for the fiber wall thickness, a pulp sheet is embedded in an acrylic resin, and a thin section made by a microtome is used.

The fiber length, fiber width, and fiber wall thickness of the pulp fiber in the present invention will be described with reference to FIG. 2. The fiber length is the dimension a in the longitudinal direction of the fiber, and the fiber width is the flatness of hollow fibers crushed. It is the dimension b of the widest part of the fiber in the direction perpendicular to the length direction. The wall thickness of the fiber is the average thickness c of the fiber cell wall in the cross section XY in the width direction of the fiber.
Is.

As described above, the smoothness of the base paper is greatly influenced by the properties of the fibers constituting the paper layer, particularly the shape of the fibers. When the weight average fiber length measured by the polarization transmission type fiber length analyzer is long, good formation cannot be obtained, shrinkage during drying of the paper layer is large, and the convex portions are difficult to be crushed during calendering, which is good. You can not get a smooth smooth. Especially, the existence rate of long fibers of 1 mm or more is important, and if it exceeds 30%, the smoothness becomes extremely poor. However, if the weight average fiber length is too short, the strength of the paper layer becomes too weak, which causes a problem in practical use. The optimum range for this weight average fiber length is between 0.5 mm and 0.85 mm.

The fiber width and the fiber wall thickness affect how the paper layer is crushed in the calender. The larger the fiber width is and the smaller the fiber wall thickness is, the more easily the fibers are crushed and the surface smoothness is increased. The effect on smoothness is that the number average fiber width is 13.5μ.
It is a region in which the number average fiber wall thickness is 4 μm or less.

However, the influences of these three factors representing the fiber shape are related to each other. In particular, the weight average fiber length and the fiber width are related to each other and are the ratio of the two, rather than treating them independently (felting power (defined by the following formula)).
Has a deeper relationship with smoothness.

FP (Fueling power) = (weight average fiber length mm)
× 1000 / (number average fiber width μm) When the value of FP is 56 or less, a remarkable effect is obtained in terms of smoothness.

Various methods are conceivable for adjusting the weight average fiber length, the number average fiber width, etc. of the pulp within a desired range. One of the methods is that the fiber shape of pulp varies greatly depending on the tree species. Therefore, a tree species suitable for the above requirements is selected, and cooking, bleaching, and pulping are performed. As another method, the pulp after bleaching is beaten. Then, there is a method of cutting the fibers and aligning the fiber lengths, and another method is to use the optimum pulp fibers after separating them by using equipment such as a screen.
Of course, the objective can be achieved by using other methods as well, if the pulp is arranged in the desired range of the present application.

The photographic printing paper support of the present invention includes an antifoggant, a filler,
It optionally contains additives usually used in papermaking, such as dyes, sizing agents, paper strengthening agents, fixing agents, and yield improving agents. If necessary, surface treatment of starch, polyvinyl alcohol, gelatin or the like, and antistatic agent treatment with sodium sulfate, sodium chloride, aluminum chloride or the like can be performed on the base paper.

Examples of the polyolefin resin include homopolymers of α-olefin such as ethylene and propylene, copolymers of two or more α-olefins such as ethylene and propylene, and other monomers having α-olefin as a main component and copolymerizable therewith. Copolymers with and mixtures thereof are preferred. Further, a white pigment such as titanium oxide or alumina, a coloring pigment, a stabilizer, an antioxidant, a dispersant, a lubricant or the like which is usually mixed with the resin may be added to the resin.

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

The smoothness of the obtained photographic paper support is described in JP-A-59-1.
According to the "Surface smoothness measuring device" described in No. 78305, the average value (A) of the amplitude of surface irregularities with a wavelength of 0.9 mm to 1.1 mm and the amplitude of surface irregularities with a wavelength of 1.8 to 2.2 mm. The average value (B) of is measured, and the smoothness is expressed by (B) / (A), and the ratio (B) / (A) is 0.
It is preferable that the ratio (B) / (A) is 1.8 in the range of 8 to 1.8.
When it exceeds the range, irregularities with a wavelength of about 2 mm begin to stand out, and the appearance as a support for photographic printing paper deteriorates. Also, (B) / (A)
When it is less than 0.8, the gloss of the surface is lost, which is not preferable.

The present invention is concerned with the amplitude of irregularities (distance between irregular peaks and troughs) having a wavelength (distance between irregular peaks) from 1.8 to 2.2 mm, which is the size of irregularities that the human eye is interested in, and it. It is a support for photographic printing paper with excellent visual smoothness, in which the amplitude ratio of the unevenness of wavelength 0.9-1.1 mm that has the effect of obscuring the image is in the range of 0.8-1.8. is there.

The polyolefin resin coated photographic paper support of the present invention is used for color photographic paper, black and white photographic paper, typesetting photographic paper, copy photographic paper and the like.

Method of Forming Paper Layer The photographic printing paper support of the present invention is a paper layer whose surface (at least one side) is coated with a thermoplastic resin, and the paper layer of this support is formed by the following procedure. .

The bleached pulp is beaten with a refiner or a beater, a retention aid for fine fibers, a filler, and a sizing agent are added, and the mixture is supplied to a paper machine, made into a sheet, and calendered after drying.

As the bleached pulp, hardwood bleached kraft pulp (LBKP) using maple as raw material chips is used alone or mixed with broadleaf bleached bisulfite pulp (LBSP), or used by mixing with other bleached pulp as raw material chips. .

The degree of beating is adjusted according to the Canadian standard water flow.

In the calendering, the linear pressure is adjusted so that the obtained web has appropriate density and smoothness.

The above formulation and manufacturing conditions differ depending on the paper machine used and cannot be generally given.

The type and mixing ratio of pulp, beating degree, and calender linear pressure are adjusted so that the formed paper layer exhibits the characteristics described in the claims.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples.

Example 1 The following conditions (1) and (2) were obtained using maple maple as a raw material chip.
LBKP was produced by cooking and bleaching with. Next is LBKP
Is beaten under the condition (3), paper is formed under the condition (4) to form a paper layer,
Then, both sides of the paper layer were coated with resin under the condition (5) to produce a photographic printing paper support.

(1) Cooking: Maximum temperature 170 ° C Liquid ratio: 5 Maximum temperature Holding time: 70 minutes Active alkali addition rate: 14% Sulfurization degree: 25% (2) Bleach: Chlorine (abbreviation C) → sodium hydroxide (abbreviation E) Bleaching is performed in the order of → sodium hypochlorite (abbreviation H) → chlorine dioxide (abbreviation D) → sodium hydroxide (E) → chlorine dioxide (D) → hydrogen peroxide (P). The temperature, time, pulp concentration and chemical addition rate of each stage are shown in Table 1.

(3) Refining: Canadian standard water degree (JIS P
-8121-76) Beat to 350 ml.

After beating, the weight average fiber length, number average fiber width and number average fiber wall thickness were measured and are shown in Table 2.

(4) Papermaking: Papermaking was performed with a Fourdrinier paper machine having a papermaking width of 500 mm at a papermaking speed of 15 m / min, and wet pressing was performed by passing a roll press having a linear pressure of 20 kg / cm twice.

For the calendering, a super calender with a linear pressure of 60 kg / cm was passed once to act as a proxy. The density was measured and is shown in Table 2.

(5) Resin coating: After performing corona treatment on calendered paper, low-density polyethylene containing 10% titanium oxide on the front surface and low-density polyethylene on the back surface at a resin temperature of 330 ° C. with an extrusion coater of 30 μm It was coated to a thickness to obtain a support for photographic printing paper. The smoothness was measured and is shown in Table 2.

Example 2 Ayaya maple and oak as a raw material chip in a weight ratio of 5: 5
Were mixed and cooked to obtain a support for photographic printing paper in the same manner as in Example 1.

Example 3 As a raw material chip, Itaya maple and wig were used in a weight ratio of 6.
The mixture was mixed at a ratio of 5: 3.5 and cooked to obtain a support for photographic printing paper in the same manner as in Example 1.

Comparative Example 1 Using oak as a raw material chip, a support for photographic printing paper was obtained in the same manner as in Example 1.

Comparative Example 2 Using eucalyptus as a raw material chip, a photographic printing paper support was obtained in the same manner as in Example 1.

Comparative Example 3 A photographic printing paper support was obtained in the same manner as in Example 1, using wigs as raw material chips.

The above results are summarized in Table 2.

[Brief description of drawings]

FIG. 1 is a mechanism diagram of a polarization transmission type fiber length analyzer used in the present invention. FIG. 2 is a schematic view of the pulp fiber, (a) is a front view of the pulp fiber with a flat surface facing upward, and (b) is a cross-sectional view of the pulp fiber having a cross section of XY. 1: light source, 2: incident optical system, 3: incident polarization filter,
4: Capillary tube, 5: Passing fiber, 6: Detection polarization filter,
7: Optical system, 8: Detection element, 9: Vacuum pump, a: Fiber length, b: Fiber width, c: Fiber wall thickness

 ─────────────────────────────────────────────────── ─── Continuation of the front page Judgment panel Chief referee Norihide Funada Judge Yuichi Ikeda Judge Takehiko Takahashi (56) References JP 58-68037 (JP, A)

Claims (1)

[Claims] 1. A pulp obtained from a raw material chip containing maple and having a weight average fiber length of 0.4 mm to 0.9 as measured by a polarization transmission type fiber length analyzer after beating the pulp.
mm number range, number average fiber width measured by microscope is 1
Pulp having a diameter of 3.5 μm or more, a number average fiber wall thickness measured in a fiber cross section of 4 μm or less, and a felting power of 56 or less, which is the ratio of the weight average fiber length to the number average fiber width, and 1 mm or less. Of which the cumulative weight fraction of the pulp fiber length is 68% or more, a paper layer is formed, and the surface of the paper layer is provided with a thermoplastic resin layer, the smoothness of the photographic paper support is 0.8.
A support for photographic printing paper, characterized in that the support is ˜1.8.