JPH09291492A - Method of making paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically and efficiently produce paper of high whiteness. SOLUTION: The web is surface-sized with a surface-sizing composition containing polyvinyl alcohol and/or a modified polyvinyl alcohol and hydrogen peroxide. The surface-sizing composition preferably has a pH of 7-9 and the modified polyvinyl alcohol is preferably a carboxy-modified polyvinyl alcohol. In addition, the saponification degree of the polyvinyl alcohol and/or modified polyvinyl alcohol is preferably >=95%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper manufacturing method, and more particularly to a method for manufacturing a paper having a high whiteness used for a support of photographic printing paper.

[0002]

2. Description of the Related Art As a support for photographic printing paper, generally, a paper coated with a gelatin-barium sulfate colloidal solution and dried, or a paper laminated with a polyolefin, especially polyethylene by an extrusion coating method, is widely used. It is used. Since paper used for such a photographic printing paper support generally requires a high degree of whiteness, chemical pulp (CP) such as kraft pulp (KP) or sulfite pulp (SP) is used in the paper conditioning step before papermaking. ) Is subjected to a multi-stage bleaching method which effectively combines oxidative bleaching with various bleaching solutions, reduction bleaching and alkali extraction.

[0003]

However, since the above method uniformly bleaches the whole pulp, a large amount of bleaching solution is required to obtain a predetermined whiteness.

The present invention has been made to solve the above problems, and an object thereof is to provide an economical and efficient papermaking method. Another object of the present invention is to provide a papermaking method capable of obtaining a paper having a high whiteness from a pulp whose whiteness is lowered due to aging.

[0005]

As a result of earnest efforts, the present invention has found that the above object can be achieved by using a predetermined surface sizing solution in the surface sizing treatment in the papermaking process.

That is, the present invention provides a paper web with at least polyvinyl alcohol and / or modified polyvinyl alcohol,
And surface sizing treatment using a surface sizing composition containing hydrogen peroxide.

Further, the present invention is characterized in that, in the above invention, the surface size composition has a pH of 7-9.

Further, the present invention is characterized in that, in the above invention, the modified polyvinyl alcohol is a carboxy modified polyvinyl alcohol.

Further, the present invention is characterized in that, in the above invention, the saponification degree of the polyvinyl alcohol and / or the modified polyvinyl alcohol is 95% or more.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

In the present invention, a surface size composition containing at least polyvinyl alcohol and / or modified polyvinyl alcohol and hydrogen peroxide is used. By improving the whiteness of the surface portion of the web in the surface size treatment, the amount of peroxide used can be significantly reduced as compared with the case of uniformly improving the whiteness of the entire pulp slurry. Further, as compared with the case of using only hydrogen peroxide in the surface size treatment, by using polyvinyl alcohol and / or modified polyvinyl alcohol together with hydrogen peroxide, it is possible to reduce the change in whiteness with time, and The amount of hydrogen peroxide used can be reduced.

Examples of the above-mentioned modified polyvinyl alcohol include carboxy-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, ethylene-modified polyvinyl alcohol and the like, and carboxy-modified polyvinyl alcohol is preferable from the viewpoint of solubility and cost. From the viewpoint of solubility in water contained in the paper web, it is preferable to use modified polyvinyl alcohol or a mixture of polyvinyl alcohol and modified polyvinyl alcohol.

The saponification degree of the polyvinyl alcohol and / or the modified polyvinyl alcohol used in the present invention is preferably 95% or more, more preferably 99% or more, from the viewpoint of enhancing the sustainability of the bleaching effect.

At this time, the pH of the surface size composition is preferably 7 or more and 9 or less. When the pH of the surface size composition is less than 7, a sufficient bleaching effect cannot be obtained, and when the pH of the surface size composition exceeds 9, hydrogen peroxide in the liquid is decomposed, which is not preferable.

Further, the above-mentioned surface size composition includes an alkali metal salt such as potassium chloride, sodium chloride, potassium sulfate, sodium sulfate, potassium nitrate, sodium nitrate, potassium carbonate and sodium carbonate, cationized starch, carboxymethyl cellulose, hydroxy. Water-soluble polymers such as ethyl cellulose, cellulose sulfate, gelatin, casein, sodium polyacrylate, styrene-maleic anhydride sodium salt, sodium polystyrene sulfonate, and petroleum resin emulsions.
Ammonium salt of styrene-maleic anhydride copolymer alkyl ester, sizing agent such as alkyl ketene dimer (AKD), latex of styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, polyethylene, vinylidene chloride copolymer, etc.・ Emulsions, glycerin, hygroscopic substances such as polyethylene glycol, clay,
Add pigments such as kaolin, talc, barium sulfate and titanium oxide, pH adjusting agents such as hydrochloric acid, caustic soda and sodium carbonate, epoxidized fatty acid amide (EFA), polyamine polyamide epichlorohydrin, dyes, optical brighteners, etc. May be.

As the surface size treatment method, a known method such as size press or tab size can be used.

In order to form the paper web used in the present invention, groundwood pulp (G
P), refiner ground pulp (RGP) and thermomechanical pulp (TMP), and other mechanical pulps (M
P), sulfite pulp (SP) and kraft pulp (K
Chemical pulp (CP) such as P), chemiground pulp (CGP), semi-chemical pulp (SCP), deinked pulp (DIP) made from waste paper, and the like can be used.

Further, these pulps may be subjected to a bleaching treatment before the surface sizing treatment. As the bleaching treatment before the surface size treatment, chlorine treatment (hereinafter abbreviated as C), alkali treatment or extraction treatment (hereinafter abbreviated as E), hypochlorous acid treatment (hereinafter abbreviated as H), chlorine dioxide treatment ( Less than,
D), alkaline peroxide treatment (hereinafter abbreviated as P), reduction bleaching treatment, and combinations thereof. For example, in the case of sulfite pulp, “CEH
In the case of kraft pulp such as "P" and "CEHDP", "C"
EHDPD ”,“ CEHEHP ”,“ CEHPHP ”,
"CEHEDP", "CEHDEDP", "CEDED"
Multi-stage bleaching such as "P" is preferably used.

As the chemicals used for the chlorine treatment, chlorine gas or chlorine water is used. Further, as the chemical used for the alkali treatment or the extraction treatment, caustic soda, calcium hydroxide, ammonia, a mixture thereof or the like is used. Further, as a chemical used for the hypochlorous acid treatment, a bleaching powder prepared by allowing chlorine to act on solid powdered slaked lime, particularly industrially, chlorine is blown into lime milk or a dilute caustic soda solution to prepare a bleached powder. A chlorous acid exposure liquid (calcium-hypo exposure liquid or sodium-hypo exposure liquid) is used. Examples of chemicals used for chlorine dioxide treatment include the Matisson method, the new Matisson method, the Elst method, C.I. I.
Chlorine dioxide prepared by a sulfite method such as P method, a hydrochloric acid method such as a Kesting method, a Nisso method, a Solvay method or the like is used. The peroxide used for the peroxide treatment is hydrogen peroxide, sodium peroxide, a peroxide exposure liquid (a mixture of hydrogen peroxide, caustic soda, sodium silicate, and magnesium sulfate added as necessary). Inorganic peroxides such as aqueous solutions), organic peroxides such as peracetic acid, t-butyl hydroperoxide, and mixtures thereof, and mixtures thereof. The alkaline solution used for the peroxide treatment includes alkali metal hydroxides such as caustic soda, potassium hydroxide, ammonium hydroxide and magnesium hydroxide, and alkaline earth metal hydroxides such as calcium hydroxide and the like. And the like. Examples of chemicals used in the reduction bleaching treatment include hydrosulfite and sodium borohydride.

A beater or a refiner can be used for beating the pulp. In addition, the beaten stock containing the above pulp as a main component, a paper strengthening agent, a sizing agent,
It is preferable to add various additives such as fillers. The additives include cationized starch, cationized polyacrylamide, anionized polyacrylamide, carboxy-modified polyvinyl alcohol and the like as a dry paper strengthening agent, and fatty acid salts, rosin derivatives such as rosin and maleated rosin, and alkyl as sizing agents. Ketene dimer, alkenyl succinic anhydride (ASA), etc. as a filler, clay, kaolin, clay, talc, calcium carbonate, titanium oxide, diatomaceous earth, barium sulfate, aluminum hydroxide, magnesium hydroxide, etc., as a wet paper strength enhancer, Polyamine polyamide epichlorohydrin, melamine resin, urea resin, epoxidized polyamide resin, fixing agent, polyvalent metal salts such as aluminum sulfate and aluminum chloride, cationic polymer such as cationized starch, caustic soda as pH adjuster ,
Sodium carbonate and the like, as well as defoaming agents, dyes, fluorescent brightening agents and the like can be mentioned, and these can be used in an appropriate combination.

Further, a paper machine, a Fourdrinier paper machine, a round net paper machine, a twin wire machine, a combination machine, etc. can be used for paper making.

The paper produced by the present invention may be used as it is as a support for photographic printing paper, or may be used by laminating plastic or the like by an extrusion method or the like. In addition to photographic printing paper, various printing paper,
It can also be used for information sheets and the like.

[0023]

EXAMPLES The present invention will be described below in detail based on examples, but the following examples do not limit the present invention.

In the following Examples and Comparative Examples, the whiteness was measured by the Hunter Whiteness measuring method of JIS P8123. Also, polyvinyl alcohol (PVA)
Regarding the dissolution characteristics, the polyvinyl alcohol concentration is 8.0
% Solution at 90 ° C was measured and
Those dissolved within 0 minutes were evaluated as ◯, and those dissolved after exceeding 30 minutes were evaluated as Δ. Furthermore, regarding the stability of polyvinyl alcohol (PVA), after the surface size composition was adjusted and allowed to stand at 40 ° C. for 30 minutes, the change in pH of the solution was 0.
Those with less than 2 were evaluated as ◯, and those with 0.2 or more were evaluated as Δ. (Example 1) Bleached kraft pulp (LBKP) with a whiteness of 81.0% made from hardwood was beaten with a double disc refiner to a Canadian standard freeness of 260 ml, and the following chemicals were added (numerical value). Is absolutely dry pulp 1
(Parts by weight per 00 parts by weight are shown). Cationized starch 1.5 AKD 0.5 EFA 0.2 Polyamine polyamide epichlorohydrin 0.3 The above paper stock was paper-made with a Fourdrinier paper machine so that the basis weight was 175 g / m ² . A paper web was impregnated with the following surface size composition maintained at a liquid temperature of 40 ° C. by a size press machine during the papermaking process, and then pressed. The size press was adjusted in advance so that the surface size composition was impregnated with 40 ml per 1 m ^{2 of the} web. [Surface size composition] 9 g of H ₂ O ₂ (33%) with respect to 100 g of water (3 g as H ₂ O ₂ pure content) caustic soda 0.001 g carboxy-modified polyvinyl alcohol (saponification degree 98%) 4.5 g sodium chloride 3 g The surface size composition had a pH of 8.0.

After pressing, it was dried at a maximum temperature of 130 ° C. with a multi-cylinder dryer. After drying, the whiteness of the paper was measured. Also, the PVA dissolution characteristics and PV of the surface size composition
A stability was tested. Table 1 shows the measurement results and the evaluation results. (Examples 2 to 6) In Example 2, a paper web was formed in the same manner as in Example 1 except that the amount of caustic soda in the surface size composition was changed to 0.0005 g. The product was tested for PVA dissolution characteristics and PVA stability. The surface size composition had a pH of 7.
It was 0.

Further, in Example 3, a paper web was formed and tested in the same manner as in Example 1 except that the amount of caustic soda in the surface size composition was changed to 0.002 g. In addition,
The pH of the surface size composition was 9.0.

In Example 4, a paper was formed and tested in the same manner as in Example 1 except that unmodified polyvinyl alcohol was used in place of the carboxy-modified polyvinyl alcohol in the surface size composition. .

In Example 5, a paper web was formed and tested in the same manner as in Example 1 except that the surface size composition containing no caustic soda was used. The surface size composition had a pH of 6.5.

In Example 6, a paper web was prepared in the same manner as in Example 1 except that a carboxy-modified polyvinyl alcohol having a saponification degree of 92% was used in place of the carboxy-modified polyvinyl alcohol having a saponification degree of 98% in the surface size composition. Were formed and tested.

Table 1 shows the measurement results, evaluation results, pH of the surface size composition, saponification degree of polyvinyl alcohol and the like. (Comparative Examples 1 and 2) Comparative Example 1 was similar to Example 1 except that the following surface size composition containing no carboxy-modified polyvinyl alcohol was used in place of the surface size composition of Example 1. Were formed and tested. [Surface size _{composition] H 2 O 2 (33%} ) in water 100g The 9g sodium hydroxide 0.001g sodium chloride 3g, in Comparative Example 2, containing hydrogen peroxide in place of the surface sizing composition of Example 1 A paper web was formed as in Example 1 except that the following surface size composition was used:
The test was performed. [Surface size composition] Carboxy-modified polyvinyl alcohol (saponification degree 98%) 4.5 g sodium chloride 3 g per 100 g water

[0031]

[Table 1]

As shown in Table 1, Examples 1 to 6 using the surface size composition containing hydrogen peroxide and polyvinyl alcohol (PVA) or carboxy-modified polyvinyl alcohol are the surface size compositions containing no hydrogen peroxide. It can be seen that the whiteness is better than that of Comparative Example 2 using the product.
In addition, these examples have a better whiteness than Comparative Example 1 using the surface size composition containing hydrogen peroxide but not polyvinyl alcohol, and thus polyvinyl alcohol and / or carboxy-modified polyvinyl along with hydrogen peroxide. It can be seen that the whiteness can be improved by using alcohol. Furthermore, comparison of Examples 1 and 6 in which the saponification degree of the carboxy-modified polyvinyl alcohol is different shows that the higher the saponification degree of the carboxy-modified polyvinyl alcohol, the better the whiteness. Also, p of the surface size composition
From the comparison between Examples 1 to 3 and Example 5 in which H is different, it can be seen that when the pH of the surface size composition is 7 or more, the pH stability of the liquid that affects the bleaching effect is improved. Furthermore, from the comparison between Example 1 and Example 4 in which whether or not the polyvinyl alcohol is carboxy-modified is different, it can be seen that the use of the carboxy-modified polyvinyl alcohol is superior in PVA solubility and shortens the dissolution time. You can see that

[0033]

INDUSTRIAL APPLICABILITY According to the present invention, since the surface sizing treatment is carried out using the surface sizing composition containing at least polyvinyl alcohol and / or modified polyvinyl alcohol, and hydrogen peroxide, the whiteness of the whiteness can be economically and efficiently achieved. High paper can be produced.

Claims (4)

[Claims] 1. A papermaking method comprising subjecting a paper web to a surface sizing treatment using a surface sizing composition containing at least polyvinyl alcohol and / or modified polyvinyl alcohol and hydrogen peroxide. 2. The papermaking method according to claim 1, wherein the surface size composition has a pH of 7-9. 3. The paper manufacturing method according to claim 1, wherein the modified polyvinyl alcohol is carboxy modified polyvinyl alcohol. 4. The paper manufacturing method according to claim 1, wherein the polyvinyl alcohol and / or the modified polyvinyl alcohol has a saponification degree of 95% or more.