JPH01229246A - Base for photographic paper - Google Patents

Abstract

PURPOSE:To improve the surface smoothness, cutting quality and hole punching property of the title base by using specific mixed cooking pulp. CONSTITUTION:The raw paper consisting of the mixed cooking pulp obtd. by mixing and cooking 5-30%, by dry weight, coniferous tree material (A) and 95-70% deciduous wood in the stage of raw material chips is used for the base of the photographic paper formed by coating both faces of the raw paper with a water resistant resin. The base having the better resistant resin. The base having the better strength, formation, cutting quality and hole punching property than in the case of mixing and using the respectively independently cooked pulps is then obtd. The strength of the raw paper is insufficient if the mixing ratio of the component A is <5%. The smoothness, cutting property and hole punching property are degraded and such degradation is undesirable if the ratio exceeds 30%.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a support for photographic paper, and more specifically, it relates to a support for photographic paper, and more specifically, a support for photographic paper that has excellent surface smoothness, cutting properties, hole punching properties, and high tear strength. This invention relates to a support for photographic paper.

[Conventional technology]

In recent years, in the industry, as a support for photographic paper (hereinafter simply referred to as support), in place of conventional baryta paper, paper has been developed that has high water resistance during development, good dimensional stability, and physical strength. A support coated with a strong, water-resistant resin is used,
Improving the efficiency of photo processing.

However, this waterproof support differs from conventional photographic paper using baryta paper in that prints can be finished without ferrotyping, so the smoothness of the surface of the photographic paper depends on the smoothness of the waterproof support itself. It is no exaggeration to say that the smoothness of the surface of a waterproof support is determined by the smoothness of the surface of the base paper, and improving the smoothness of the surface of the base paper is a major issue.

Furthermore, the water-resistant support has problems with hole-punching properties and cutting properties of the support, which will be described below.

That is, a roll-shaped support coated with an emulsion is printed, developed, and then cut into sheets of a predetermined size, but in this cutting process, the cuttability of the support is poor. The cutting edge is dirty, and there is a lot of paper dust.
Problems such as adhesion of cut chips to the printed surface of the support often occurred.

Furthermore, since the cutting process is automated, cutting marks are made by punching holes in the support or by stamping on the surface of the support before the cutting process. However, when cutting by hole punching and reading the hole punched hole, the cutting ability of the support is poor, so it is necessary to cut a circle with a diameter of about 0.5 to 1jEII or a similar size. Problems often occurred in that the rectangular holes were filled with whiskers such as pulp fibers and polyethylene resin, making detection impossible with phototubes and the like, and that the support was not cut.

As a way to solve these problems, the base paper for the waterproof support is made from a raw material mainly consisting of hardwood pulp, which can easily obtain good formation and good smoothness. In order to reduce the stiffness of the fibers and improve the cutting and hole punching properties, the viscosity is reduced to a very low viscosity.
Bleaching is performed to weaken the single fiber strength to some extent. Furthermore, when using it, it is beaten with a low-free Nenu 1.

However, when paper is manufactured using such hardwood pulp, the strength of the paper is inevitably low.9 In particular, the tear strength decreases significantly because the fiber length is short and the single fiber strength is low. It's beautiful.

Therefore, softwood pulp is generally added to reinforce this. However, the formulation of softwood pulp
=If increased, the formation, cutting performance, and hole-punch performance will deteriorate, so efforts are currently being made to balance these properties and strength by adding 5 to 30% softwood pulp. be.

[Problem that the invention seeks to solve]

The present invention maintains the strength of the photographic base paper covering the water-resistant resin, smooths the surface of the base paper to make the surface of the water-resistant resin layer on which the photographic emulsion is completely coated, and further improves the hole punching properties of the base paper. The object of the present invention is to provide a water-resistant support that has improved hole-punchability and cutability of the entire support by improving the hole-punching and cutting properties of the support.

[Means for solving problems]

The inventors of the present invention have investigated all means to solve all of the above-mentioned problems, and have found that a pulp obtained by mixing hardwood and softwood at the raw material chip stage and cooking and bleaching in this state is used. The present invention was completed by discovering that it is possible to obtain a base paper that maintains strength and has good texture, cutting properties, and hole punching properties.

That is, the present invention provides a photographic paper support comprising a base paper coated on both sides with a water-resistant resin, in which the base paper is made of dry heavy violet and is made of 5 to 50% softwood wood and 95 to 70% hardwood wood. This support for photographic paper is characterized in that it is made of a mixed cooked pulp obtained by mixing and cooking at the chip stage.

Typically, mixing and cooking softwood and hardwood wood is
In particular, it is strictly avoided if the hardwood material is a living body.

The reason for this is that hardwood has a lower lignin content than softwood and has better digestibility, so when mixed cooking, hardwood will cook faster than softwood, so that the hardwood has an optimal degree of digestion. At that time, the softwood wood was still undigested,
This is because even if the number of valves is reduced to 11, a large amount of bundled fibers will still be generated.

However, when the present inventors subjected a mixed material of hardwood and softwood containing 5 to 30% softwood to strong cooking and strong bleaching, it became clear that no undigested material was generated which would cause problems. Ta.

This is thought to be because the raw material containing a small amount of softwood chips was overcooked at 1 to reduce the viscosity, and during this time, the softwood material also progressed to the point where no bundled fibrils were produced.

In other words, in such strong cooking and strong bleaching, it has been found that even if softwood chips and hardwood chips are not strongly cooked and strongly bleached individually, their functions can be fully demonstrated by mixed cooking and mixed bleaching. Served next.

By using the mixed pulp thus obtained,
A water-resistant support with excellent strength, texture, cuttability, and hole-punching properties can also be obtained by using a pulp that is a mixture of singly digested hardwood pulp and softwood pulp.

The cooking method in the present invention may be a sulfite method or a 1gk hydrochloride salt method, or may be a variety of modified methods thereof. Cooking and bleaching conditions can basically be the same as for single cooking of hardwood materials.

In addition, the mixed material of hardwood and softwood used for cooking is
5-30% softwood wood chips and 95% by dry weight of chips
It is best to mix it with ~70% hardwood chips. If the mixing ratio of softwood wood is less than 5%, the strength of the base paper will be insufficient,
If it exceeds 30%, the smoothness, cutting performance, and hole punching performance of the base paper will deteriorate.

To mix the chips, it is convenient to feed hardwood and softwood chips separately by metering them at the chip bin feed port for continuous cooking, or at the wood pot feed port for patch cooking. be.

Further, the bleaching method may be any combination of conventional methods such as chlorine treatment, alkali treatment, salt industry bleaching, oxygen bleaching, peroxide bleaching, and reducing agent bleaching. In addition, to increase the purity of the pulp, pre-hydrolysis is used when cooking with the sulfate method, high-temperature alkaline extraction is used when cooking with the sulfite method, and Belmar treatment is used in combination to control pulp viscosity. It's okay.

The base paper used in the present invention is mainly composed of mixed pulp, but if necessary, within a range of 20%,
Base paper made of a mixture of singly digested pulp, synthetic pulp, and synthetic fibers may also be used.

The base paper containing mixed cooked pulp gold as a main component used in the examples of the present invention contains 4! It is preferable to include r types of additives. For example, as a dry paper strength enhancer, cationized starch,
Cationized polyacrylamide, anionized polyacrylamide, carboxy-modified polyvinyl alcohol, as a sizing agent, fatty acid salt, rosin, rosin derivatives such as maleated rosin, dialkyl ketene dimer, alkenyl or alkyl succinate, epoxidized fatty acid amide, Polysaccharide esters, etc. as fillers, clay, kaolin, calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, magnesium hydroxide, etc. as wet paper strength enhancers, melamine resin, urea resin, epoxidized polyamide wood strength. As fixing agents, polyvalent metal salts such as aluminum sulfate and aluminum chloride, cationic polymers such as cationized starch, etc., are used as fixing agents, and as modifiers, caustic powder, soda carbonate, etc. It is advantageous to contain appropriate combinations of other dyes, colored pigments, fluorescent whitening agents, and the like.

The base paper used in the practice of the present invention is advantageously tab-sized or size-pressed with a liquid containing various water-soluble polymer additives.

Examples of such water-soluble polymer additives include cationized starch, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, cellulose sulfate, gelatin, casein, sodium polyacrylate, and styrene-maleic anhydride copolymer. Sodium salts, sodium polystyrene sulfonate, etc. are used, and as sizing agents, petroleum resin emulsions, ammonium salts of styrene-maleic anhydride copolymer alkyl esters, alkyl ketene dimer emulsions, etc. are used, styrene-butadiene copolymers, Latexes or emulsions such as ethylene-vinyl acetate copolymer, polyethylene, vinylidene chloride copolymer, etc. are used as inorganic electrolytes, salt, calcium chloride, mirabilite, etc. are used as hygroscopic substances, glycerin,
Polyethylene glycol etc. are used as pigments, clay,
Kaolin, talc, barium sulfate, titanium oxide, etc.
- Hydrochloric acid, caustic soda, carbonate powder, etc. are used as regulators, and it is advantageous to use them in combination with other additives such as dyes, color pigments, and optical brighteners.

There are no particular restrictions on the thickness of the base paper whose main component is mixed cooked pulp used in the practice of the present invention, but base paper with good surface smoothness is obtained by compressing the base paper by applying pressure in a calendar after making the paper. Preferably, the basis weight is 50 to 250
9/rx2 is preferred.

The water-resistant resin used in the present invention is a resin having film-forming ability, and is a homopolymer of α-olefins such as ethylene and propylene, or a copolymer consisting of two or more α-olefins such as ethylene and propylene. Preference is given to copolymers based on α-olefins with other monomers copolymerizable therewith and mixtures thereof. In addition, white pigments such as titanium oxide, zinc oxide, Merck, calcium carbonate, and alumina, glass fiber,
Fibrous fillers such as asbestos and whiskers, carbon black, phthalocyanine pigments, coloring pigments such as yellow lead, titanium yellow, red iron oxide, and ultramarine, stabilizers that are usually mixed with resins, antioxidants, antistatic agents, and plasticizers. , a dispersant, a lubricant, an optical brightener, etc. may be added.

The support coated with the water-resistant resin of the present invention is coated by a general method such as extrusion coating or solvent coating, and depending on the resin, may be subjected to a treatment such as electron beam curing. Alternatively, the resin may be formed into a film in advance and then laminated by dry lamination or wet lamination.

Usually, it is manufactured by a so-called extrusion coating method in which heated and molten resin gold is cast onto a running base paper, and both sides of the paper are coated with resin.

Furthermore, it is preferable to subject the base paper to an activation treatment such as a corona discharge treatment or a flame treatment before being completely coated with the resin. The emulsion side surface of resin-covered paper has a glossy surface, a matte surface, a silky surface, etc. depending on the use, and the back surface is usually a matte surface, and corona is applied to the front surface or both the front and back surfaces as necessary. Activation treatments such as discharge treatment and flame treatment can be performed. In addition, there is no particular limit to the thickness of the resin layer of resin-coated paper, but
Generally extrusion coatings to a thickness on the order of 5-50 microns are advantageous.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to this.

The manufacturing conditions for the pulp used in the examples using the sulfite method and the sulfate method are as follows.

(1) Sulfite method a) Mixed cooking pulp Mixed chips consisting of 15 parts of softwood chips and 85 parts of hardwood chips were cooked under the conditions shown in Cooking Condition 1 in Table 1. The cooking yield was 44.5%. After cooking, bleaching was carried out under the conditions shown in Bleaching Condition 1 in Table 2 to obtain a mixed cooked pulp with a viscosity of 16 centipoise (measurement method: Tappi T 250om-82).

Mouth) Hardwood pulp Hardwood chips were cooked under the same conditions as for mixed pulp. The steaming yield was 44.0%. After cooking, bleaching was carried out under the conditions shown in Bleaching Condition 2 in Table 2 to obtain pulp (LBSP) with a viscosity of 12 centivoise.

c) Softwood pulp Softwood chips were cooked under the conditions shown in Cooking Condition 2 in Table 1. The cooking yield was 46.0%. After cooking, bleaching was carried out under the conditions shown in Bleaching Condition 3 in Table 2 to obtain pulp (NBSP) with a viscosity of 20 centivoise.

Table 1 Note 2) The addition rate of O/2 and Na010 is shown in the amount of active chlorine.

(2) Sulfate Method A) Mixed Cooked Pulp Mixed chips consisting of 15 parts of softwood chips and 85 parts of hardwood chips were all cooked under the conditions shown in Cooking Condition 3 in Table 3. The cooking yield was 45.0%. After cooking, bleaching was carried out under the conditions shown in Bleaching Condition 4 in Table 4 to obtain a mixed cooked pulp with a viscosity of 6.5 centivoise.

Mouth) Hardwood pulp Hardwood chips were cooked under the same conditions as for the fully mixed cooked pulp. The cooking yield was 44.5%. After cooking, bleaching was performed under the same conditions as for mixed cooked pulp, and the viscosity was 5.0.
Centivoice Pulp (LBKP)'i got it.

c) Softwood pulp Softwood chips were cooked under the conditions shown in Cooking Condition 4 in Table 3. The cooking yield was 45.8X. After cooking, bleaching was carried out under the conditions shown in Bleaching Condition 5 in Table 4 to obtain pulp (NBKP) with a viscosity of 12.0 centiboise.

Table 3 Table 4 Note 2) 072. NaG10. The addition rate of ClO2 is indicated by the amount of available chlorine.

Furthermore, evaluations of smoothness, cutting properties, and hole punching properties in the present invention were conducted as follows.

(1) Smoothness Three-dimensional roughness measuring instrument (model S E-5A K.

Evaluation was made by measuring the center surface average roughness (SRa) of the surface (emulsion coated surface) of the support using a micrometer (manufactured by Koita Research Institute). The measurement was carried out according to the method described in Japanese Patent Application Laid-Open No. 61-260240.

(2) Cutting performance A tabletop slitter (Rotatrim, manufactured by Rota trill in the UK) is used to cut the base paper of the support in the vertical direction (machine direction) from the surface toward the JI surface. A sensory evaluation was performed by comparison, and a score was given using a 5-point system with 5 points being the best.

(3) Hole punching property ゛Using an office-grade punching machine, holes are punched from the front side of the support to the back side.
A sensory evaluation was performed by visual comparison of the cut pieces, and scores were given using a 5-point system with 5 points being the same.

In addition, % in Examples (including Comparative Examples) indicates all percentages by weight.

Example 1 A mixed pulp obtained by cooking and bleaching mixed chips by the sulfite method was used as a raw material.

The above pulp is coated with JF-Fner and Canada Standard Freeness (JIS P-Ez2t-76) 250.
After beating to ILt, the following 9 times of papermaking chemicals were added at absolute dryness indication for pulp.

Cationized starch 2.0% Alkyl ketene dimer Jugetsu 0.4X anionic polyacrylamide resin 0.1% Caustic powder
...adjusted to 7.0 Paper was made using a Fourdrinier machine using all of the above chemicals, and passed through a size press and a machine calendar to obtain a base paper with a basis weight of 170 m, a tensile strength of 1.0, and a moisture content of 8 S.

The size press chemical was prepared by dissolving carboxyl-modified py7° and sodium chloride in water at a ratio of 2:1 to form a 5% size solution, which was coated on both sides at a rate of 2.29/m2.

This base paper was completely subjected to corona discharge, and the front surface was coated with high-density polyethylene (specific gravity 0.94, Mr=6.8) containing 10% anatase type titanium dioxide, and the back surface was coated with 320% high-density polyethylene containing no pigment. The paper was extruded to a thickness of 28 μm at 20° C. and pressed onto a cooling roll at 20 μm with a linear pressure of 20 μm to obtain a water-resistant 11-fat paper.

Table 5 shows the evaluation results of the characteristics of the obtained water-resistant support.

Example 2 Taharup (
A water-resistant support was entirely produced in the same manner as in Example 1, except that a mixture of 10% (NBSP) and 90% of the mixed cooked pulp used in Example 1 was used as the raw material.

Table 5 shows the evaluation results of the properties of the obtained support.

Comparative Example 1 Hardwood pulp (L
BSP) and softwood pulp (NBSP)
A water-resistant support was produced in the same manner as in Example 1, except that a mixture of P/NBSP = 85/15 was used as the raw material.

Table 5 shows the evaluation results of the properties of the obtained support.

Example 3 A water-resistant support was produced in the same manner as in Example 1, using mixed chips obtained by cooking and bleaching by the total sulfate method as a raw material.

Table 5 shows the evaluation results of the properties of the obtained support.

Example 4 Pulp (N
BKP) 10% and mixed cooked pulp 90 used in Example 3
A water-resistant support was entirely produced in the same manner as in Example 1, except that a mixture of % and % was used as the raw material.

Table 5 shows the evaluation results of the properties of the obtained support.

Comparative Example 2 Hardwood pulp (L
BKP) and softwood pulp (NBKP) to LBKP/
A water-resistant support was entirely produced in the same manner as in Example 1, except that a mixture of NBKP at a ratio of 85/15 was used as the raw material.

Table 5 shows the evaluation results of the properties of the obtained support.

As is clear from Table 5, in both the sulfite and sulfate cooking methods, it is possible to use all of the mixed pulp, but it is not possible to mix the single-cooked hardwood pulp and softwood pulp. All properties were also good, confirming the effects of the present invention.

〔Effect of the invention〕

The effects of the present invention are as follows.

1. A support for photographic paper with good strength, texture, cutting properties, and hole punching properties can be obtained.

2. Since softwood and hardwood are mixed in the necessary proportions at the raw material chip stage, the complexity of cooking softwood and hardwood separately is avoided, and equipment and processes are greatly simplified.

Patent applicant: Oji Paper Co., Ltd.

Claims (1)

[Claims] 1. In a photographic paper support formed by coating both sides of a base paper with a water-resistant resin, the base paper is made of 5 to 30% soft resin material and 95 to 70% hardwood material by dry weight at the stage of raw material chips. 1. A support for photographic paper, characterized in that it is made of a mixed pulp obtained by mixing and cooking the pulp.