JP2001303473A - Offset printing paper and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an offset printing paper having good printing quality and printing workability by efficiently improving the surface strength of printing paper such as Vessel pick strength with a small amount of a surface treatment agent. SOLUTION: The dry oxidized modified starch obtained by using hydrogen peroxide as an oxidizing agent, the dry oxidized modified starch having an aldehyde group content of 0.05% by weight or more of the dry oxidized modified starch as a main component. Offset printing paper obtained by applying a surface treating agent to the surface of base paper and drying; and a dry oxidized modified starch obtained by using hydrogen peroxide as an oxidizing agent, wherein the content of aldehyde groups is the dry oxidized starch. the surface treating agent for the dry oxidation modified starch is 0.05 wt% or more modified starch composed mainly 0.05 to 1 g / m ² was coated on one side per solid equivalent to the surface of the base paper, characterized in that the drying Offset printing paper manufacturing method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing paper, and more particularly to a printing paper, such as newsprint, which contains a high content of waste paper pulp (DIP). The present invention relates to an offset printing paper capable of effectively preventing a reduction in printing workability and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, offset printing, color printing, and high-speed printing have been rapidly progressing, and there has been a demand for more excellent color printing suitability and printing workability for printing paper as a printing medium. Recently, as a printing paper, a paper mainly composed of mechanical pulp or waste paper pulp has been used. In particular, from the viewpoint of environmental problems such as an increase in trash and resource saving, high use ratio of waste paper is required. By the way, waste paper raw materials mainly composed of recovered newsprint, such as those used for printing paper, contain a large number of leaflets and the like containing hardwood, in addition to newsprint, uncoated paper, coated paper, and the like. When used waste paper is used as a raw material for printing paper, as the amount of used paper increases, a large amount of vessel (conduit) peculiar to hardwood pulp is mixed into the printing paper base paper, and as a result, near the surface of the printing paper base paper. When the scattered vessels peel off from the paper surface during printing, white spots (vessel pick) of a printed image occur, and there is a problem that print workability and print quality deteriorate.

[0003] Offset printing is a method in which dampening water and ink are supplied to a printing plate, ink is transferred to a rubber plate called a blanket, and then transferred to paper for printing. Compared with the letterpress printing method that was used, in order to use printing ink with relatively strong tack,
Printing paper is required to have high surface strength. If the surface strength is weak, so-called blanket piling, where fibers released from the paper due to paper peeling, fillers and paper powder contained in the printing paper, etc. accumulate on the blanket, and when they are mixed with ink, printing on the paper surface A so-called blur occurs on the surface, and troubles such as a decrease in print quality and a decrease in print workability occur. In particular, the above-described troubles of the vessel picking, which occur within a relatively short time from the start of printing, as compared with blanket piling due to paper dust, filler, and the like, and printing fraying, etc. When this occurs, there is a problem that not only the print quality is deteriorated, but also complicated work such as blanket cleaning is increased and the printing workability is significantly reduced.

As a method for coping with the problem of surface strength reduction during offset printing as described above, a surface treatment agent containing starch, polyvinyl alcohol (PVA), polyacrylamide or the like as a component has conventionally been applied to the surface of printing paper. This is generally done, but it is scattered near the surface of the paper, and when compared to fine fibers and fillers, much coarser vessels remain on the paper surface without picking during printing. For this purpose, a method of increasing the amount of the surface treatment agent as described above and preventing the vessel from being dropped is generally employed. However, when the use amount of the surface treatment agent increases, not only does the cost increase, but also the paper surface tends to increase the adhesiveness of the paper surface called wetness when the paper surface is wet. In particular, blanket piling in a non-image area may be increased, or the paper may stick to the blanket during printing, resulting in another problem such as wrinkles or paper breakage, which is not preferable. Particularly, continuous printing for a long time has a drawback that a sufficient improvement effect cannot always be obtained. Among these surface treatment agents, starch and polyacrylamide are widely used due to their relatively low nepari properties, but all of them have high solubility in water, so they are easily dissolved in dampening water during printing. It has the drawback that it is easily deposited on the blanket together with the filler.

[0005] In view of the above situation, various methods have been conventionally proposed, especially for the problem of vessel picking. For example, JP-A-6-220790 discloses a method of treating a pulp slurry containing hardwood with a kneader at a high concentration, and JP-A-10-266090 discloses a printing paper or a base paper for coating printing containing ozone-treated hardwood pulp. JP-A-10-273897 proposes a coated paper containing a specific styrene-butadiene-based copolymer latex and starch. However, these methods are difficult to apply to waste paper pulp due to high equipment costs and high cost, and relatively low U.S.P., such as newsprint, and waste paper pulp of 40% or more. In fact, the effect of improving the Bessel pick strength is not sufficient in the proportion blending.

[0006]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention efficiently improves the surface strength of printing paper, such as Vessel pick strength, with a small amount of a surface treatment agent, and improves print quality.
An object of the present invention is to provide offset printing paper having good printing workability and a method for manufacturing the same.

[0007]

Means for Solving the Problems The present inventors have reviewed and studied the use of starch as a surface treating agent for printing paper. As a result, by using a specific dry oxidatively modified starch, the surface strength of printing paper containing a large amount of DIP, especially represented by newsprint, is improved, and blanket piling and neppari properties during offset printing are efficiently improved. And completed the present invention.

The present invention includes the following inventions. (1) A dry-oxidized modified starch obtained by using hydrogen peroxide as an oxidizing agent, the dry-oxidized modified starch having an aldehyde group content of at least 0.05% by weight of the dry-oxidized modified starch as a main component. Offset printing paper obtained by applying a surface treating agent to the surface of base paper and drying. (2) A dry oxidized modified starch obtained by using hydrogen peroxide as an oxidizing agent, the dry oxidized modified starch having an aldehyde group content of 0.05% by weight or more of the dry oxidized modified starch as a main component. A method for producing offset printing paper, comprising applying a surface treating agent to the surface of the base paper at 0.05 to 1 g / m ^{2 in} terms of solid content per one side, followed by drying.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The surface treatment agent used in the present invention is a dry oxidized modified starch obtained by using hydrogen peroxide as an oxidizing agent, wherein the content of aldehyde group is 0.05% of the dry oxidized modified starch. The main component is a dry oxidized modified starch that is not less than weight%. Dry oxidatively modified starch obtained by using hydrogen peroxide as an oxidizing agent has good water resistance and sliminess of the sizing agent, and has a dry oxidatively modified starch having an aldehyde group content of 0.05% by weight or more. With starch, vessel picking and blanket piling during printing are improved. The content of the aldehyde group is from 0.05 to 0.05 of the dry oxidation-modified starch.
Preferably, it is 3.0 weight.

[0010] The dry oxidation-modified starch used in the present invention is preferably prepared by adding hydrogen peroxide as an oxidizing agent to a starch, adding a metal catalyst as an oxidation promoter, and adding an acid if necessary. ) It can be produced by heat roasting to oxidatively modify starch. By producing in this manner, an aldehyde group is generated preferentially over a carboxyl group.

The starch used in the present invention includes, for example, corn starch (corn starch), potato starch, tapioca starch, wheat starch, sweet potato starch, rice starch, and modified starches based on these. In the present invention, hydrogen peroxide is used as an oxidizing agent to oxidize starch. Hydrogen peroxide includes commonly available aqueous solutions of hydrogen peroxide,
That is, a hydrogen peroxide solution is preferable, and the hydrogen peroxide concentration is 75%.
More preferred is an aqueous solution of not more than% by weight.

Examples of the metal catalyst used in the present invention include transition metals of Groups 3A to 6A, 8 and 1B to 2B of the periodic table, preferably iron, cobalt, nickel, copper, zinc,
More preferably, divalent copper, divalent iron, divalent zinc, and divalent cobalt are used. The acid used for the acidic condition is not particularly limited, for example, sulfuric acid, phosphoric acid, hydrochloric acid,
Examples thereof include inorganic acids such as nitric acid and organic acids such as formic acid, acetic acid, oxalic acid, malonic acid, and dimethyl sulfuric acid. Sulfuric acid, phosphoric acid, hydrochloric acid, and acetic acid are preferably used.

A preferred method for producing the dry oxidation modified starch used in the present invention is described below. The aldehyde group content is 0.05% by weight or more, preferably 0.05 to
In obtaining 3.0% by weight of dry oxidized modified starch,
The amount of hydrogen peroxide used as an oxidizing agent is 1 to starch.
It is preferably at most 2% by weight. The used amount is 12
If the amount is more than 10% by weight, there is a danger that a sudden reaction may occur when the mixture is heated with the starch, and the starch may be liquefied by the generated water. The amount of the metal catalyst used is preferably such that the metal content is 0.05% by weight or less based on the starch, and 0.0005 to 0.05.
More preferably, it is% by weight.

When hydrogen peroxide, a metal catalyst and an acid are mixed with the starch, the amount of the acid to be mixed is adjusted so that the pH of a 10% by weight slurry of the starch mixture is 5 or less, preferably 2 to 4. The starch mixture is dried so that the moisture content of the starch mixture is usually 30% by weight, preferably 25% by weight, more preferably 20% by weight or less.
By heating and roasting at a temperature of 100C, preferably 100 to 130C, a dry oxidation-modified starch can be obtained. By appropriately selecting the amount of the above-mentioned chemicals (hydrogen peroxide, metal catalyst and acid), the reaction temperature and the reaction time, the content of the aldehyde group used in the present invention is 0.05% by weight, preferably 0.0% by weight.
It is possible to obtain a dry oxidation modified starch having a content of 5 to 3.0% by weight.

In the present invention, a dry roasting method is used as the heating roasting method. This dry roasting method is called
This is a known method described in Japanese Patent No. 205512, specifically, a mixed solution of a reaction reagent and water is impregnated in starch, or a highly concentrated solution of the reaction reagent is impregnated in starch.
Alternatively, after spraying the above-mentioned mixed solution or high-concentration solution on starch, stirring the mixture until it becomes uniform, and then subjecting the mixture to a heating reaction using a stirring dryer, a stationary dryer, or the like. It is.

The reason why the use of the dry oxidized modified starch improves the surface strength of a vessel pick and the like is not clear, but is presumed as follows. Aldehyde groups in the dry oxidatively modified starch form chemical bonds with hydroxyl groups in the pulp fiber, increasing the adhesion between pulp and starch,
Surface strength increases. In addition, since the dry oxidatively modified starch has good water absorption, excess moisture on the paper surface due to adhesion of dampening water during offset printing is absorbed before moving into the pulp fiber,
Prevents interception of hydrogen bonds between hydroxyl groups of pulp fiber by water absorption.Furthermore, since this dry-oxidized modified starch is hard to elute in water, the strength of the starch itself is maintained, and as a result, the strength of both pulp fiber and starch is maintained. Think.

The surface treating agent used in the present invention comprises the above-mentioned dry oxidized modified starch as a main component. Optional components include, for example, other adhesives, a defoaming agent, a waterproofing agent, and a surface sizing agent. And various auxiliaries such as preservatives and the like can be appropriately compounded. As the other adhesive, for example, various modified starches, latexes such as styrene-butadiene copolymer,
Examples include polyvinyl alcohol and polyacrylamide. The ratio of the dry oxidized modified starch to the total solids in the surface treatment agent is usually 50 to 100% by weight, and preferably 60 to 100% by weight. The amount is appropriately adjusted depending on the amount of coating to be performed, but is usually in the range of 2 to 15% by weight.

The surface treating agent obtained as described above is
Coating equipment commonly used in the papermaking field, for example, using a device such as a size press, a blade metaling size press, a rod metaling size press, a gate roll coater, a blade coater, a bar coater, a rod blade coater, an air knife coater, etc. as appropriate. It is applied to one or both sides of the base paper surface.

The surface treatment agent is applied using such an apparatus.
The amount of application when clothing is 0.05 to
1g / m^TwoIs applied and dried. 0.0
5g / m^TwoIf less, the effect of improving the vessel pick
Is insufficient, while 1 g / m ^TwoApply to exceed
In addition to cost increase, another problem such as Nepali
Occurs undesirably.

After the surface treating agent is applied and dried,
If necessary, the paper is passed through a calender, pressurized and smoothed to finish the product. As a calendering device in this case, using a soft calender having a metal roll / resin roll configuration rather than a normal machine roll using a metal roll / metal roll combination smoothes the base paper layer without strongly pressing it. It is more preferable because it can suppress the decrease in paper layer strength.

Next, as pulp constituting the base paper,
Chemical pulp (bleached or unbleached NKP or LKP
), High yield pulp (GP, CGP, RGP, PG
W, TMP, etc.), used paper pulp (DIP, etc.) and the like are mixed and used at an arbitrary ratio. In the papermaking, if necessary, an amorphous silica-based inorganic pigment such as white carbon, calcined kaolin, structured kaolin, and titanium dioxide, and further a paper-making filler such as urea-formaldehyde resin are appropriately added to the stock. Can be added.

Further, in the stock, together with the filler, general sizing agents such as a sulfuric acid band, a paper strength enhancer, a retention improver, a reinforced rosin sizing agent, an emulsion sizing agent, a water-proofing agent, and an ultraviolet ray inhibitor. Papermaking chemicals are added, and the paper is made on a normal paper machine. In the case of the present invention, the basis weight of the base paper is not particularly limited, but is usually 30 to 45 g.
/ M ² .

[0023]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to the following Examples. In the following, parts and% indicate parts by weight and% by weight, respectively, unless otherwise specified. The method for measuring the aldehyde group content in starch is described below.

(Method for Measuring Aldehyde Group Content) The starch was washed with methanol, and the washed residue was air-dried. Water was added to 2.0 g of the washed starch to make a slurry of about 1%,
It was gelatinized by heating at 5 ° C. for 30 minutes. Cool the size liquid to room temperature and adjust the pH to 1.5 or less with sulfuric acid.
Oxidation-reduction titration was performed by dropping a 0.05 mol / l aqueous solution of potassium permanganate, and the amount of aldehyde groups was calculated from the titration value. The end point of the titration was defined as a time point at which the reddish purple color of potassium permanganate did not disappear for 1 minute or more after a drop of 0.05 mol / l aqueous solution of potassium permanganate was dropped. The calculation formula is as follows. The blank was a raw starch.

[0025]

(Equation 1)

Example 1 (Preparation of dry oxidation modified starch) Commercial corn starch 1
6 parts of 30% aqueous hydrogen peroxide and 0.02
And an aqueous solution containing 0.01 part of copper (II) sulfate pentahydrate were mixed to obtain a homogeneous mixture (pH 3.5) containing 30% of water. This mixture was dried at 100 ° C. until the water content became 12% or less, and then heated and roasted at 120 ° C. for 80 minutes using a hot air circulation type heater. The dry oxidized corn starch having an aldehyde group content of 0.4% was measured by the above-mentioned method for measuring the aldehyde group content.

(Preparation of base paper) Softwood kraft pulp (N
KP) 10 parts, thermomechanical pulp (TMP) 40
A pulp slurry was prepared by beating a pulp slurry having a ratio of 5 parts by weight, ground pulp (GP), and 45 parts of newspaper deinked waste paper pulp (DIP) to a freeness (csf) of 120 ml with a refiner. A rosin emulsion size (product name:
SPN-773 / Arakawa Chemical Co., Ltd.), 0.3% of sulfuric acid band, 2% of white carbon having an average particle diameter of 22 μm (all based on pulp solid content) to prepare a stock. The paper material was used to make a paper using a twin-wire type paper machine to obtain a base paper having a rice area of 40 g / m ² .

(Preparation of Newspaper) As a surface treatment agent, the previously prepared dry oxidized corn starch was heated and dissolved with hot water to prepare a surface treatment agent having a solid content of 12%. Then, using a gate roll coater, both sides of a 40 g / m ² base paper obtained by making this surface treating agent with the above-mentioned paper machine were dried to a weight of 0.3 g / m ² per side. After applying and drying so as to obtain the following, 1 nip treatment was performed with a soft calender to obtain newsprint with a moisture content of 8%.

Example 2 70 parts of the dry oxidized corn starch used in Example 1 was mixed with a phosphate esterified starch (trade name: GRC40 / Oji Cornstarch Co., Ltd., aldehyde group content: 0.51)
%) By heating and dissolving 30 parts with hot water to prepare a surface treatment agent having a solid concentration of 10%, and a weight after drying of 0.2 g / side per side.
Newspaper was obtained in the same manner as in Example 1 except that the coating was performed so as to obtain m ² .

Example 3 70 parts of dry oxidized corn starch used in Example 1 were oxidized corn starch (trade name: Ace A, manufactured by Oji Cornstarch, aldehyde group content: 0.51%)
30 parts were heated and dissolved with hot water to prepare a surface treating agent having a solid content of 13%, and the weight after drying was 0.3 g / m ² per side.
Newspaper was obtained in the same manner as in Example 1 except that the coating was performed so as to be as follows.

Example 4 80 parts of the dry oxidized corn starch used in Example 1 and 20 parts of polyacrylamide (trade name: NP14 / manufactured by Mitsui Chemicals, Inc.) were dissolved by heating with hot water, and the solid content concentration was 10%.
Of the surface treatment agent, and the weight after drying is 0.3
Newspaper was obtained in the same manner as in Example 1 except that the coating was performed so as to give g / m ² .

COMPARATIVE EXAMPLE 1 A method for preparing a dry oxidized modified starch of Example 1 except that 4 parts of 30% hydrogen peroxide solution was used and a heating and roasting reaction was carried out at 100 ° C. for 10 minutes using a hot air circulation type heater. In the same manner as described above, a dry oxidized corn starch having an aldehyde group content of 0.03% was obtained. The obtained dry oxidized corn starch was heated and dissolved with hot water to prepare a surface treatment agent having a solid content of 12%, and the surface treatment agent was applied such that the weight after drying was 0.3 g / m ² per side. Newspaper was obtained in the same manner as in Example 1.

Comparative Example 2 In Example 1, the surface treatment agent was 100% oxidized corn starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.).
A newsprint was obtained in the same manner as in Example 1, except that the weight after drying was 0.3 g / m ² per side.

Comparative Example 3 In Comparative Example 2, the weight after drying was 0.6 g / side / side.
except that the m ² was obtained newsprint in the same manner as in Comparative Example 2.

Comparative Example 4 Example 1 was repeated except that the surface treatment agent was polyacrylamide (trade name: KS533 / Arakawa Chemical Co.) and the weight after drying was 0.4 g / m ² per side. Newspaper was obtained in the same manner as described above.

Comparative Example 5 Example 1 was repeated except that the surface treatment agent was polyvinyl alcohol (trade name: PVA115 / Kuraray Co.) and the weight after drying was 0.2 g / m ² per side. In the same manner, newsprint was obtained. Examples 1 to 4 and Comparative Example 1
The following quality evaluations were performed on the newsprints obtained in Nos. 1 to 5, and the obtained results are shown in Table 1.

(Blanket Piling) Using an offset printing machine (Komori SYSTEM C-20 / Komori Corporation), after printing 10,000 copies, color four-color printing was performed, and the degree of deposition of paper dust in the blanket non-image area was performed. Was visually determined. The criteria are shown below. ：: No generation of paper dust was observed. Δ: Generation of paper powder is slightly observed. ×: A lot of paper powder is deposited on the blanket.

(Vessel Pick) Offset Printing Press (Komori SYSTEM C-20 / Komori Corporation)
Is used to perform monochrome printing of an offset rotary printing ink (black ink) having a dot area ratio of 30 to 100%, and a dot area ratio of 1
The degree of white spots caused by the 00% solid portion of the vessel was visually determined. The criteria are shown below. A: Almost no white spots are observed. Δ: White spots are slightly observed. ×: Many white spots are generated.

(Nepari strength) Two newsprint samples were cut into appropriate sizes, immersed in water for 10 seconds, and then brought into close contact with each other, passed through a calender at a linear pressure of 100 kg / cm, and kept at room temperature for 24 hours. After drying, a sample having a width of 3 cm was prepared in the form of a strip having a width of 3 cm, and the peel strength of the paper of 3 cm width was measured using a tensile tester. The higher the value, the higher the tackiness.

[0040]

[Table 1]

[0041]

According to the present invention, it is possible to provide offset printing paper which is excellent in surface strength such as Vessel pick strength and free from troubles such as blanket piling.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Suminaga 4-3-1 Jokoji, Amagasaki-shi, Hyogo Oji Paper Co., Ltd. Amagasaki Research Center (72) Inventor Yorihiro Masumoto 4-3-1 Jokoji, Amagasaki-shi, Hyogo No. 1 Oji Paper Co., Ltd. Amagasaki Research Center (72) Inventor Mitsuo Ishida 9 Yawata Kaigan-dori, Ichihara City, Chiba Prefecture Oji Corn Starch Co., Ltd. Address Oji Cornstarch Co., Ltd. Development Laboratory F-term (reference) 4L055 AG04 AG48 AH13 AH50 AJ02 BE08 EA29 FA13 FA15 GA15

Claims (2)

[Claims] 1. A dry oxidized modified starch obtained by using hydrogen peroxide as an oxidizing agent, the dry oxidized modified starch having an aldehyde group content of at least 0.05% by weight of the dry oxidized modified starch. Offset printing paper obtained by applying a surface treating agent as a component to the surface of the base paper and drying. 2. A dry oxidized modified starch obtained by using hydrogen peroxide as an oxidizing agent, the dry oxidized modified starch having an aldehyde group content of at least 0.05% by weight of the dry oxidized modified starch. A method for producing offset printing paper, comprising applying a surface treating agent as a component to a surface of a base paper in an amount of 0.05 to 1 g / m ^{2 in} terms of solid content per one side, and drying.