JP2897582B2 - Method for producing a support for photographic printing paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a photographic paper support. To elaborate further,
The present invention relates to a method for producing a photographic printing paper support having high whiteness and less fading.

[0002]

2. Description of the Related Art In recent years, with the speeding up of photo development processing,
In place of the conventionally used baryta paper, a support for water-resistant photographic printing paper in which both sides of a base paper are coated with a polyolefin resin has been used.

The properties required for a photographic paper support include excellent dimensional stability, moisture resistance, adhesiveness, and smoothness, and do not adversely affect the photographic emulsion layer. In particular, its hue is important. The hue of the surface of the photographic emulsion coated surface of the photographic printing paper support is preferably pure white, and when this hue is shifted toward yellow or red,
The image formed on the photographic paper has a dull or completely dull appearance. Therefore, various methods for improving the whiteness of the support have been studied so far. As an example, the following method has been proposed.

(1) A method of incorporating a white pigment in a polyolefin coating layer (for example, Japanese Patent Application Laid-Open No. 55-108658)
(2) A method of applying a white pigment to the surface of a polyolefin coating layer (for example, JP-A-59-177542) (3) A method of dyeing pulp with a blue dye to improve the apparent whiteness of the base paper ( (For example, JP-A-58-105228) (4) Method of increasing whiteness of base paper by using pulp having high whiteness Among these methods, (4) is the most effective method,
Usually, this method is used.

[0005] The bleached pulp used for the support is required not only to have high whiteness but also to have stability of whiteness, that is, pulp characteristics which are not easily faded. The stability of whiteness is measured by measuring the whiteness of a pulp after exposing it to heat for a certain period of time. The bleaching degree (The Bleachin) is calculated from the difference in whiteness before and after the exposure.
g of Pulp, P358, TAPPI PRESS 1979), that is, a PC value (post color number). The stability of whiteness is greatly affected by the bleaching sequence or bleaching conditions.

JP-B-58-43732 describes a method for producing bleached pulp for a support using an alkaline peroxide. When hydrogen peroxide is used as the peroxide, the literature (The Bleaching of Pulp,
P382, P384, TAPPI PRESS (1979), N. Hartler, TAPPI
43 (11) 903 (1960)), the higher the temperature, the higher the addition rate and the longer the time, the better the discoloration. However, peroxides are expensive and have explosive properties, and care must be taken when handling them. Hydrogen peroxide, which is the most commonly used peroxide for bleaching, is corrosive, so it is necessary to select the material for the reaction vessel. A paper support bleach is desired.

[0007] Hypochlorite is inexpensive, has bleaching properties comparable to hydrogen peroxide, and is easier to handle than hydrogen peroxide and the like. However hypochlorite, have an adverse effect on the fading, the higher the addition rate, the higher the temperature, you worse fading the longer the time (TheBleaching o
f Pulp, P383, TAPPI PRESS (1
979). This is said to be due to the introduction of carbonyl groups at the ends of the cellulose chains of bleached pulp by hypochlorite exposure (WH Rapson, CB Ande).
rson, G .; F. King, TAPPI 41 (8) 4
42 (1958)). Further, the bleaching property is improved as the hypochlorite exposure temperature is increased, but there is a problem that the pulp viscosity is greatly reduced at a high temperature. As described above, hypochlorite exposure is effective in improving whiteness,
It was believed that the bleaching pulp had only a negative effect on the fade and quality.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photographic printing paper support having a high whiteness and less fading, and a whiteness which can be used for the support. It is an object of the present invention to provide a base paper that is high and has little discoloration. In particular, pulp with high whiteness that does not cause deterioration in discoloration and decrease in pulp viscosity by effectively utilizing hypochlorite bleaching An object of the present invention is to produce a support for photographic printing paper using a base paper produced by using the method.

[0009]

DISCLOSURE OF THE INVENTION The present inventors have conducted various studies on pulp for base paper which can be used as a support having the above-mentioned characteristics, and as a result, have found that the alkali addition rate is lower than that of ordinary hypochlorite. After hypochlorite exposure under conditions of excess addition than bleaching, subsequent chlorine dioxide exposure results in a small decrease in viscosity and whiteness despite hypochlorite exposure at high temperatures. That pulp with a high pulp content can be obtained. When the strong alkali hypochlorite exposure and chlorine dioxide exposure are performed at the high temperature, not only the whiteness is further improved, but also
The present invention has been made based on the discovery of a surprising effect that the discoloration can be greatly improved.

The present invention relates to a method for producing a support for photographic paper by coating both sides of a base paper with a polyolefin resin, wherein the bleaching sequence of the pulp comprises, as a base paper, a hypochlorite stage, a chlorine dioxide stage, Hypochlorite stage,
Look including a continuous sequence of chlorine dioxide stage, at least one stage of hypochlorite stages of the consecutive sequence found alkali addition rate (versus absolute dry pulp weight per) from 1.0 to 4.
The present invention relates to a method for producing a support for photographic printing paper, wherein a base paper produced from pulp produced according to a bleaching sequence, which is a step of bleaching at a high temperature of 60 to 120 ° C., at an alkali of 0% by weight , is used. It is.

Further, the present invention relates to a bleaching sequence of pulp used for base paper as a bleaching sequence of one or more of a high-temperature, strongly alkaline hypochlorite stage (H) and a chlorine dioxide stage (D). By combining D) with a chlorine stage (C), an alkali stage (E), a normal hypochlorite stage (H), and a chlorine dioxide stage (D), high whiteness and excellent fading are obtained. The present invention relates to a method for manufacturing a photographic paper support at low cost.

In the process of the present invention, the hypochlorite used in the high temperature, strongly alkaline hypochlorite stage is substantially calcium hypochlorite or sodium hypochlorite. Considering workability, sodium hypochlorite (hypo) is good. The rate of addition of hypo per absolute dry pulp weight is between 0.1% and 3% by weight, preferably between 0.5% and 1.5% by weight.

The alkali used as an auxiliary agent can be selected from many alkaline compounds known to those skilled in the art, but caustic soda is the easiest to use. NaOH addition rate per absolute dry pulp weight is abnormally higher than normal hypo bleaching, between 1% and 4% by weight, preferably between 1.5% and 2.5% by weight . The reaction temperature is also higher than normal hypobleaching, between 60 ° C and 120 ° C, preferably between 70 ° C and 100 ° C.

The pulp concentration is the same as in ordinary hypo bleaching,
The reaction time is between 30 and 150%.
Minutes, the final pH is between 8 and 12.5.
After the H stage, the washing or compression step is performed subsequently, as in the other stages.

The ClO ₂ used in the subsequent chlorine dioxide stage can be obtained from many ClO ₂ generation processes known to those skilled in the art.
It can be selected from lO _2. Per absolute dry pulp weight
Addition rate of ClO ₂ is between 3% to 0.2% by weight ClO ₂ terms, the reaction temperature is between 100 ° C. from 40 ° C., a pulp concentration of the reaction time is between 5% and 15% The reaction time is between 15 and 300 minutes and the final pH is between 2 and 6.

The bleaching method of the pulp used for the base paper for photographic printing paper of the present invention is not limited to chemical pulp such as kraft pulp (KP), alkali pulp (AP), and sulfite pulp (SP), but also modified continuous steam. Solution (Modified Continuous Coo
pulp obtained from the king), after cooking by the usual craft method,
After cooking with oxygen bleached pulp and modified continuous cooking,
It is also applicable to oxygen bleached chemical pulp. Needless to say, the invention can be applied to both wood pulp and non-wood pulp.

[0017]

Next, an embodiment of the present invention will be described.
The present invention is not limited by these examples. In the following examples, the bleaching conditions of a continuous sequence of high-temperature, strongly alkaline hypo and chlorine dioxide stages, production of a photographic paper support, measurement and testing of the whiteness of bleached pulp and photographic paper support Was based on the following operating means.

[0018] High-temperature, strongly alkaline hypo-stage and chlorine dioxide
Continuous sequence of steps ( HD) Pulp is put into a plastic bag, 2.5% by weight of alkali and 1% by weight of hypo pulp are added, and the concentration is reduced to 10% by adding deionized water. After adjusting,
Stir well and hold at 90 ° C. for 3 hours. After the reaction was completed, the sample was taken out of the bag, washed, and centrifugally dehydrated. The pulp after centrifugal dewatering is again put into a plastic bag, and 1.0% by weight.
Was added ClO ₂ of (ClO ₂ equivalent), after adjusting the concentration with ion-exchanged water, thoroughly stirred, and held for 3 hours at 90 ° C..

Production of Photographic Paper Support A bleached pulp was beaten to a Canadian freeness of 300 ml to prepare a pulp slurry. In addition, an alkyl ketene dimer resin as a sizing agent was 0.4% by weight per absolute dry pulp weight, an anionic polyacrylamide resin as a strength agent was 0.1% by weight per absolute dry pulp weight, and a cationized starch was absolutely dry. 2.0% by weight based on the weight of the pulp and 0.7% by weight of the polyamide polyamine epichlorhydrin resin based on the weight of the absolutely dry pulp were added, and diluted with water to obtain a 1% slurry. Paper was made from this slurry and passed through a drier, a size press, and a machine calender to produce a base paper for photographic printing paper having a basis weight of 170 g / m ² , a tightness of 1.0 g / m ³ , and a water content of 8%. The size press chemical was prepared by mixing carboxyl-modified PVA and sodium chloride in a ratio of 2: 1, dissolving the same in water, and applying a 5% size liquid to both sides of the paper at an application amount of 25 g / m ² .

On one side of the base paper, high-density polyethylene (density 0.951 g / cm ³ , melt index = 9 g / 1)
0 min) and low density polyethylene (density 0.918g / c)
(M ³ , melt index = 4 g / 10 min) was extruded at a resin temperature of 330 ° C. and matted with a cooling roll to form a resin coating layer having a thickness of 30 μm. On the other surface, a polyethylene resin (density = 0.
926 g / cm ³ , melt index = 16 g / 10 min, 50 parts by weight of linear low density polyethylene, and density = 0.
918 g / cm ³ , melt index = 4 g / 10 min, a mixture with 50 parts by weight of low-density polyethylene) was extruded and applied at a resin temperature of 320 ° C. to form a resin coating layer having a thickness of 30 μm. Formed to produce a photographic paper support.

Measurement of Pulp Whiteness and Discoloration Test The whiteness of pulp was measured according to JIS P8123. The bleaching test was performed by bleaching the bleached pulp in a circulating air oven at 105 ° C. for 2 hours.
The PC value was calculated according to the following formula and displayed. [(1-after photobleaching whiteness) ^2/2 × after photobleaching whiteness - (1-
Fading before whiteness) ^2/2 × fade before whiteness] × 100

Measurement of Whiteness of Photographic Paper Support and Discoloration Test The whiteness of the photographic paper support was measured in accordance with JIS P8123. In the fading test, the photographic printing paper support immediately after production was sealed in a black low-density polyethylene bag of 100 μm,
The samples were stored for 4 weeks in a constant temperature and humidity of 40 ° C. and 80% RH.

Example 1 Unbleached hardwood pulp (mixture of hardwood in Japan; whiteness 26.
2%, Kα value 18.3) Take 50 g of absolutely dry in a plastic bag, add 2.8% by weight of chlorine per weight of pulp, add ion-exchanged water to adjust the concentration to 10%,
Stir well and hold at 45 ° C. for 30 minutes. After completion of the reaction, the washed and centrifugally dewatered pulp is placed in a plastic bag, 1.0% by weight of alkali is added, ion-exchanged water is added to adjust the concentration to 10%, and the mixture is sufficiently stirred.
C. for 1 hour. After the completion of the reaction, washing, centrifugal dehydration,
A continuous sequence exposure (HD) of a hypo-alkali stage and a chlorine dioxide stage at high temperature was performed.

After completion of the reaction, the washed and centrifugally dewatered pulp is placed in a plastic bag, 0.3% by weight of hypo is added, and the concentration is adjusted to 10% by adding ion-exchanged water.
Stir well and hold at 45 ° C. for 1.5 hours. After the completion of the reaction, the washed and centrifugally dewatered pulp is placed in a plastic bag, 0.3% by weight of chlorine dioxide (in terms of ClO ₂ ) is added, ion water is added to adjust the concentration to 10%, and the mixture is sufficiently stirred. And kept at 70 ° C. for 2.5 hours. After the reaction,
Washed and centrifugally dehydrated bleached pulp (C-E- (HD) -H
-D sequence) was used as the base paper for photographic printing paper.
Table 1 shows the results.

Example 2 The same unbleached hardwood pulp as in Example 1 was used for CEHD-
It was bleached in the (HD) sequence and used as a base paper for photographic printing paper. Table 1 shows the results.

Example 3 The same unbleached hardwood pulp as in Example 1 was prepared using CE- (H-
It was bleached in a D)-(HD) sequence and used as a base paper for photographic printing paper. Table 1 shows the results.

Example 4 The same undried hardwood pulp (50 g) as in Example 1 was dried in an autoclave, and 2.6% by weight of alkali and 1.5% by weight of oxygen were added per weight of pulp. And adjust the concentration to 10%.
For 40 minutes. After completion of the reaction, the washed and centrifugally dewatered pulp is placed in a plastic bag, 1.4% by weight of chlorine is added, ion-exchanged water is added to adjust the concentration to 10%, and the mixture is thoroughly stirred at 45 ° C. Hold for 30 minutes. After completion of the reaction, the washed and centrifugally dewatered pulp is placed in a plastic bag, 0.5% by weight of alkali is added, ion-exchanged water is added to adjust the concentration to 10%, and the mixture is sufficiently stirred.
C. for 1 hour.

After the completion of the reaction, washing, centrifugal dehydration, and continuous sequence exposure (HD) of a high alkali hypo-stage and a chlorine dioxide stage at a high temperature were performed. After completion of the reaction, the washed and centrifugally dewatered pulp is placed in a plastic bag, 0.3% by weight of hypo is added, the concentration is adjusted to 10% by adding ion-exchanged water, and the mixture is stirred sufficiently at 45 ° C. Hold for 1.5 hours. After the completion of the reaction, the washed and centrifugally dewatered pulp is placed in a plastic bag, 0.3% by weight of chlorine dioxide (in terms of ClO ₂ ) is added, the concentration is adjusted to 10% by adding ion-exchanged water, and then sufficiently. Stir and hold at 70 ° C. for 2.5 hours. After the reaction, washed and centrifugally dehydrated bleached pulp (OCE-
(HD) -HD sequence) was used as a support base paper for photographic printing paper. Table 1 shows the results.

Example 5 The same unbleached hardwood pulp as in Example 1 was prepared using OCEH-
It was bleached in a D- (HD) sequence and used as a base paper for photographic printing paper. Table 1 shows the results.

Example 6 The same unbleached hardwood pulp as in Example 1 was prepared using OCE- (H
It was bleached in a -D)-(HD) sequence and used as a base paper for photographic printing paper. Table 1 shows the results.

Comparative Example 1 The same unbleached hardwood pulp as in Example 1 was prepared using CEHD-
It was bleached in the HD sequence and used as a base paper for photographic printing paper. Table 1 shows the results.

COMPARATIVE EXAMPLE 2 The same unbleached hardwood pulp as in Example 1 was prepared using OCEH-
It was bleached in a DHD sequence and used as a base paper for photographic printing paper. Table 1 shows the results.

[0033]

[Table 1]

[0034]

From the above Table 1, it can be seen that a photographic printing paper support manufactured by using pulp bleached in a sequence containing at least one continuous sequence of a high-temperature, strongly alkaline hypo-stage and a chlorine dioxide stage as base paper is as follows: It is clear that the whiteness is high and the fading is significantly improved. When the whiteness of the photographic printing paper support is high and the color is hardly faded, the appearance of the photographic printing paper is clear, and the sharpness can be maintained for a long time.

──────────────────────────────────────────────────続 き Continued on the front page (72) Katsuaki Onishi, Inventor Katsuaki Onishi 1850 Todaka, Oji, Nichinan City, Miyazaki Prefecture Oji Paper Co., Ltd. Nichinan Mill (56) References JP-A-4-222286 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) G03C 1/775 D21C 9/14

Claims (2)

(57) [Claims] 1. A method for producing a photographic paper support by coating both sides of a base paper with a polyolefin resin, wherein the bleaching sequence of the pulp is a hypochlorite stage, a chlorine dioxide stage, a hypochlorite stage, Acid salt stage, chlorine dioxide
Look including a continuous sequence of steps, at least one stage of hypochlorite stages in the continuous sequence are alkali addition rate (versus absolute dry pulp weight per) of 1.0 to 4.0 wt% <br A method for producing a support for photographic printing paper, comprising using a base paper produced in accordance with a bleaching sequence, which is a step of bleaching at a high temperature of 60 to 120 ° C., which is alkaline. 2. The bleaching sequence of the pulp used for the base paper includes a chlorine stage, an alkali stage, a hypochlorite stage, a chlorine dioxide stage,
2. The method for producing a photographic printing paper support according to claim 1, comprising a continuous sequence of a hypochlorite stage and a chlorine dioxide stage.