JP2002069890A - Water-resistant printing paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-resistant printing paper solving problems to achieve such as the coexistence of high water resistance and beating performance, coexistence of the water resistance and workability in offset printing or the like, which are impossible in a conventional one, reducing strength degradation or dimensional change by suppressing penetration of water, having an excellent printability for offset printing such as surface hardness and drying property of an ink and having the beating performance capable of recycling of wastepaper after use. SOLUTION: This water resistant printing paper requiring a structure installing water resistant layers to inhibit water penetration on both sides of a paper support having the defibrability and a strong sizing property and then installing printing layers, the water resistant layers have to be composed of a styrene-butadiene copolymer latex having a glass transition temperature of -10 to 50 deg.C and the application quantity of the water resistant layer is important. The oil absorbing property of the loading material used in the loading material coating layer and the formulating amount of the loading material and application quantity of the coating material are set in a specific relationship in the printing layers to satisfy the surface strength and drying property of the ink in the offset printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a conventional paper which has almost no reduction in paper strength due to water by suppressing water penetration into paper and has water resistance close to that of synthetic paper. The present invention relates to a water-resistant printing paper which has suitable printing workability without any problem of ink setting at the time of offset printing using process ink and has a disintegration property which can be recycled as used paper after use.

[0002]

2. Description of the Related Art In order to maintain the strength of a conventional water-resistant printing paper even when the paper itself gets wet, a large amount of a wet paper strength enhancer is added to the paper, or the paper is impregnated with latex to form a bond between fibers. Although some measures were taken to reinforce and apply a coating to make it more difficult for water to penetrate, these waterproof papers have poor disintegration properties,
There is a problem that it cannot be reused after use. further,
Commercially available printing papers based on synthetic paper as printing paper with extremely high water resistance, and sheets that combine water resistance and printability by attaching a polyolefin film or polyester film to the paper and applying a print receiving layer However, they are also difficult to reuse, and their disposal is a problem.

[0003] In order to solve such problems, the penetration of water into paper is reduced as much as possible to maintain the water-resistant strength.
As a water-resistant printing paper having a disintegrating property that can be recycled as used paper after use, a paper provided with a hydrophobic resin layer such as a mixture of a polyethylene resin, a synthetic rubber-based dispersion and paraffin wax or a fatty acid ester on the surface of the paper is known. It has become. Also, JP-A-2000-805
In Japanese Patent No. 95, there is disclosed a water-resistant printing which makes it difficult for water to permeate into paper by applying a coating composed of 50 to 100 parts of an acrylic dispersion per 100 parts of a raw material, and which at the same time disintegrates when reused. Paper has been proposed.

[0004] However, these water-resistant printing papers form a water-resistant layer having a high barrier property on the front and back surfaces of the paper when ink is sufficiently suppressed to prevent water from seeping into the paper. In particular, when performing four-color printing, the second color printing is performed before the first color is absorbed by the paper. .
In addition, there is a clear relationship between sufficient water resistance and disintegration, and there is also a problem that the disintegration becomes worse as the water is hardly permeated. Furthermore, when water resistance is imparted to both the front and back sides, a high barrier layer is formed on the front side first, and when coating the back side, there is no escape of moisture remaining in the base paper, causing a blister problem between the paper layers. And the coating layer on the back surface foams.

[0005]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to solve the above-mentioned problem which has been a problem in the conventional water-resistant printing paper, and to reduce the strength of the paper by suppressing water seepage. It is an object of the present invention to provide a water-resistant printing paper which has an offset printing suitability such as surface strength and ink drying property, eliminates dimensional changes, etc., and has a disintegration property that can be recycled even when used as used paper after use.

[0006]

The present inventors have conducted intensive studies to solve the above problems, and as a result, first provided a water-resistant layer for preventing water penetration on both sides of a paper support, and then performed printing. It is necessary to provide a structure in which layers are sequentially provided, and in order to achieve both waterproofness and disaggregation with respect to the water-resistant layer, -10 to 5
It was found that it was composed of a styrene-butadiene copolymer latex having a glass transition temperature of 0 ° C., and that the coating amount was important. Also, regarding the printing layer, in order to satisfy the surface strength and ink drying property during offset printing,
The inventors have found that the oil absorption of the filler used in the filler coating layer is related to the compounding amount of the filler and the coating amount of the paint, thereby completing the present invention.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the waterproof printing paper of the present invention is as follows.
The water-resistant layer and the printed layer must be laminated in this order on both sides of the paper support. Even if the two properties are satisfied with one layer, if the water resistance increases, the drying of the ink for offset printing deteriorates, and if the suitability for offset printing is imparted, the water resistance deteriorates.

The glass transition temperature of the styrene-butadiene copolymer latex used in the water-resistant layer is -10 to 50.
Must be within ° C. When the temperature is lower than -10 ° C, a continuous film having a barrier property is formed and the waterproof property is good, but the disintegration property is deteriorated, and blocking occurs when the film is wound after coating. If it exceeds 50 ° C., the disintegration is good, but the water resistance is insufficient.

[0009] The styrene-butadiene copolymer of the present invention is a styrene-butadiene copolymer constituting the copolymer latex.
The sum of the amount of acid groups bound or adsorbed on the surface of the butadiene copolymer and the amount of acid groups in the aqueous phase of the copolymer latex is 0.4 to 3.5 milligrams per gram of copolymer in terms of hydrochloric acid equivalent. It is preferably equivalent. If it is less than 0.4 milligram equivalent, water resistance tends to decrease,
Even when the amount exceeds 3.5 milligram equivalent, the waterproofness of the water-resistant layer tends to decrease.

The acid group includes a carboxyl group, a sulfonic group, a phosphinyl group and the like. In order to improve the water resistance, it is preferable to increase the amount of these acid groups bonded or adsorbed on the surface of the copolymer and to reduce the amount of these acid groups in the aqueous phase of the copolymer latex. When the amount of acid groups in the aqueous phase is large, even if the amount of acid groups on the surface of the copolymer is the same, the waterproofness of the water-resistant layer tends to decrease.

[0011] The coating amount of the water-resistant layer must be in the range of ^{3 to} 12 g / m2. When it is less than 3 g / m ² , the water resistance is insufficient, and when it exceeds 12 g / m ² , not only the disintegration property is deteriorated, but also the barrier property on the front surface becomes perfect and the water-resistant layer on the back surface is coated. There is no escape for base paper moisture,
Blisters occur between the paper layers of the base paper, and foaming problems occur in the back coating layer.

[0012] The printing layer is a filler-coated layer, and among 100 parts by weight of the filler, the filler having an oil absorption of 100 to 300 ml / 100 g measured according to JIS K 5101 is 10 to 10 parts by weight.
40 parts by weight are used, and the coating amount is 5 to 15 g / m ^2.
Must. These conditions are for preventing the problem of drying of the ink during offset printing, and for preventing the filler on the surface from being taken off by the blanket of the blanket due to the tackiness of the ink and causing the problem of paper dust. . When the oil absorption is less than 100 ml / 100 g, the compounding ratio of these fillers is less than 10 parts by weight, or the coating amount is less than 5 g / m ² out of 100 parts by weight of the filler, the set drying property of the ink is poor. Poorly, problems such as backing, trapping, and rubbing stains occur when printing. When the oil absorption exceeds 300 ml / 100 g or when the compounding ratio of the filler exceeds 40 parts by weight, the coating amount is 15
If it exceeds g / m ² , the surface strength will be weak, and when performing normal offset printing, a filler will be taken into the blanket, which may cause a paper dust problem.

The filler having an oil absorption of 100 to 300 ml / 100 g includes calcium silicate as an inorganic filler,
Examples include hydrous silicic acid, aluminum silicate soda, amorphous silica, and secondary aggregated calcium carbonate.
Examples of the organic filler include those having a through-hole connecting the surface to the inside of the particles, and spherical secondary particles composed of fine particles having a primary particle of 0.5 μm or less. Although the material of the organic filler is not particularly limited, for example, polystyrene, polymethyl (meth) acrylate, polyvinyl chloride, polyurethane, polyvinylidene chloride, poly (meth)
Resins such as acrylonitrile, or copolymers having these resin components, such as styrene-acrylic copolymers, may be mentioned.

Among the fillers to be incorporated in the printing layer, as the filler having an oil absorption other than 100 to 300 ml / 100 g, any filler used as a filler for ordinary paper coating materials can be used. For example, one kind of inorganic pigments such as kaolin, calcium carbonate, barium sulfate, titanium dioxide, talc, zinc oxide, magnesium oxide, bentonite, zeolite, and sericite, and organic pigments such as polystyrene resin, urea resin, melamine resin, and acrylic resin. Alternatively, it is also possible to mix two or more kinds. Any chemicals used in ordinary paper coatings can be used for coating composition of the printing layer. Examples of the filler adhesive include various modified starches, polyvinyl alcohol, casein, soy protein, styrene-butadiene-based copolymer latex, acrylic latex, vinyl acetate-based latex, urethane-based latex, and nitrile-butadiene-based copolymer Latex and the like. Two or more of these adhesives may be mixed and blended as needed. However, assuming that the water-resistant printing paper of the present invention is used outdoors, such as a poster, it is preferable to use an acrylic latex in consideration of light resistance. Furthermore, in addition to this, a dispersant, a pH adjuster,
Water retention agents, lubricants, defoamers, preservatives, fluorescent dyes, dyes, coloring pigments, water-proofing agents, and the like can be used as necessary.

The present inventors have found that by adding 2 to 8 parts by weight of a solid content weight ratio to a filler of 100 parts by weight of a polyethylene oxide as an antiblocking agent to a print layer, the surface strength is not reduced, It has been found that the set drying property of the ink is improved. This is thought to be because these waxes do not melt at about the drying temperature of the paint, so that the form is maintained, the structure of the coating layer is made more porous, and ink absorption is improved. If the amount of these oxidized polyethylene waxes is less than 2 parts, the effect is not clearly exhibited, and if added more than 8 parts, the effect is not improved, and not only is it economically disadvantageous, There is a disadvantage that the print layer surface is too slippery.

As a method for applying the water-resistant layer and the printing layer to the base paper, generally known coating apparatuses such as a blade coater,
Apparatuses such as an air knife coater, a roll coater, a reverse roll coater, a bar coater, a curtain coater, a die slot coater, a gravure coater, a bill blade coater, a short dwell coater, and a gate roll coater can be appropriately used in combination.

The water-resistant printing paper in which the water-resistant layer and the printing layer are sequentially laminated on the base paper as described above has different measurement conditions according to JISP 8140-98.
30 ° C., 80% RH for 24 hours or more, test water temperature: 30 ° C.,
Contact time with water: The water absorption of the cobb measured in one hour must be 30 g / m ² or less on both sides. If the water absorption of the Cobb exceeds 30 g / m ² under these measurement conditions, the water resistance becomes insufficient as compared with a commercially available water-resistant printing paper.
The tensile strength in a wet state is greatly reduced as compared with the tensile strength in a dry state, and a desired water-resistant printing paper cannot be obtained.

The base paper used in the present invention needs to have a disintegration property under ordinary conditions, as is apparent from the necessity of the disintegration property in the constitution of the present invention. No matter how much the coating layer is devised for the base paper without disintegration, the disintegration cannot be improved. Therefore, the amount of the wet paper strength enhancer that inhibits the disintegration must be limited. Many water-resistant printing papers have been configured so that a large amount of wet strength agent is added to the base paper to maintain the strength even when wet with water. It was impossible. Therefore, the upper limit of the amount of the wet paper strength enhancer added to the base paper used in the present invention is an amount capable of defibration. For example, polyamide which is frequently used as a wet paper strength enhancer
When polyamine-epichlorohydrin is added, the amount must be 0.8 parts by weight or less based on 100 parts by weight of papermaking pulp. If the added amount exceeds 0.8 parts by weight, the disintegration property is poor, and it is difficult to reuse. However, if the amount of addition is such that the disintegration is not impaired, it is preferable to add a wet paper strength enhancer since the strength can be maintained when water permeates.

As the wet paper strength enhancer to be added, urea-formaldehyde resin, melamine-formaldehyde resin, polyethyleneimine and the like can be appropriately used as chemicals other than polyamide-polyamine-epichlorohydrin. In addition, polyacrylamide, various modified starches, vegetable gums, CMC, and the like can be appropriately added as a dry paper strength enhancer that does not significantly inhibit the disintegration.

In the water-resistant printing paper of the present invention, since a water-resistant barrier layer is formed on the front and back sides, it is possible to suppress water penetration from the front and back sides, but it is also possible to prevent penetration from the exposed end face of the paper. Need to be prevented. Therefore, it is preferable to add 0.8 to 2.0 parts by weight of the modified rosin emulsion sizing agent at a solid content weight ratio to 100 parts by weight of the pulp for papermaking raw material used in the base paper. If the amount is less than 0.8 parts by weight, the effect of preventing water from penetrating from the end face is not sufficient,
Even if it is added in excess of 2.0 parts by weight, the effect of preventing permeation is not improved, which is not only economically disadvantageous but also causes a problem of soiling with a wet press or the like during papermaking. Further, simply adding the modified rosin emulsion to the pulp suspension alone does not easily fix the rosin emulsion to the pulp. Therefore, it is desirable to fix the rosin emulsion by adding a sufficient aluminum salt.

As the pulp used in the base paper of the present invention, any pulp can be used. For example, as wood pulp, hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood bleached sulphite pulp (LB
Chemical pulp such as SP), softwood bleached sulphite pulp (NBSP), mechanical pulp such as groundwood pulp (GP), thermomechanical pulp (TMP), and used paper pulp. As the non-wood pulp, cotton pulp, hemp, bagasse, kenaf, esparto, mulberry, mitsumata, ganpi etc. can be used. Synthetic pulp and inorganic fibers can be used as necessary. However, considering that the present invention is used for outdoor posters and the like, and considering light resistance, it is preferable to use a chemical pulp especially for wood pulp.

Since the present invention is used for printing, the base paper is required to have smoothness and opacity. It is preferable to add a filler in order to impart smoothness and opacity to the base paper. The filler to be added is not particularly limited. For example, talc, kaolin, clay, calcined kaolin,
Delamikaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium dioxide, zinc hydroxide, magnesium sulfate, magnesium silicate, calcium sulfate, calcium silicate, white carbon, aluminosilicate Mineral fillers such as salts, silica, sericite and smectite, and organic synthetic fillers such as polystyrene resin fine particles, urea formalin resin fine particles, and fine hollow particles.

In addition, various papermaking auxiliaries can be appropriately selected and used as needed. For example, there are a retention improver, a drainage improver, a dye, a fluorescent brightener, a pH adjuster, a defoamer, a pitch control agent, a slime control agent and the like.

In making the raw material prepared by adding various chemicals as described above, a fourdrinier paper machine,
Circular web paper machine, twin wire former, single web paper machine,
Alternatively, any paper machine such as a combination of these paper machines can be applied. Further, it is preferable to perform the water permeation preventing process by a size press in the paper making process. As the size press chemicals at this time, modified starch such as oxidized starch, polyvinyl alcohol, polyacrylamide,
Chemicals commonly used in a normal size pressing process, such as styrene-acryl, can be used in the same manner, but styrene-acryl is most preferable from the viewpoint of water permeation prevention properties and the like.

[0025]

EXAMPLE 1 Commercially available softwood bleached kraft pulp and hardwood bleached kraft pulp were charged into a pulper at a weight ratio of 50:50, sufficiently disintegrated at a solids concentration of 5%, and beaten with a double disc refiner. 400 ml of raw pulp was prepared with Canadian Standard Freeness. Thereafter, a modified rosin emulsion sizing agent (trade name “Size Pine N-771”, manufactured by Arakawa Chemical Co., Ltd.) was added to the mixing tank at a solid concentration of 1% based on the weight of the pulp, and a wet paper strength enhancer (product) Name "WS-547", Japan PMC Inc.
Was added at a solid concentration of 0.5%, and then a 4% sulfuric acid band was added and sufficiently stirred to obtain a prepared stock. Using this stock, a fourdrinier paper machine uses a basis weight of 100 g / m ^2.
Was made into a base paper for coating.

With respect to the base paper thus formed, the following items were evaluated. <Disintegration> 1 cm x 1 cm for 800 ml of water
Was put into a household mixer and stirred for 2 minutes. A hand-made sheet having a basis weight of 100 g / m ² was prepared from the obtained pulp slurry. If the size of defibrated pieces of undisintegrated material is 1 mm x 1 mm or less,
m × 1 mm to 5 mm × 5 mm, Δ: 5 mm × 5 mm or more

Using this base paper as a water-resistant layer, it is a styrene-butadiene copolymer latex having a glass transition temperature (Tg) of 13 ° C., and the amount of acid groups bonded or adsorbed on the surface of the styrene-butadiene copolymer. And a latex (trade name “Nipol Z400S”, manufactured by Nippon Zeon Co., Ltd.) in which the sum of the amount of acid groups in the aqueous phase of the copolymer latex is 2.0 mg equivalent per g of the copolymer in terms of hydrochloric acid equivalent.
Was coated on the surface of the base paper at a solid content of 8 g / m ² using an air knife coater.

Subsequently, as a printing layer, JIS K51
Porous calcium carbonate having an oil absorption of 140 ml / 100 g measured according to the trade name “CALLITE-K
T "(manufactured by Shiraishi Industry Co., Ltd.), 30 parts by weight of wet heavy calcium carbonate (trade name" F
MT-90 ", 50 parts by weight of FIMERTECH CO., LTD., And 20 parts of titanium oxide (trade name" A-220 ", manufactured by Ishihara Sangyo Co., Ltd.) were mixed, and an acrylic binder (trade name" A-220 ") was used as a binder. Nipol LX-852B "(manufactured by Nippon Zeon Co., Ltd.) with a filler in an amount of 15 parts by weight using a blade coater at a solid content of 8 g / m2.
^2. Coated on the water-resistant layer on the surface.

In the same manner, the reverse side of the base paper was coated in the order of a water-resistant layer and a printing layer, and then subjected to a super calender treatment to complete a water-resistant printing paper.

The water-resistant printing paper manufactured as described above was evaluated for the following items. <Cobb water absorption>
In accordance with JIS P 8140-98, as different measurement conditions, sample humidity control conditions: 30 ° C., 80% RH 24
The measurement was performed at a test water temperature of 30 ° C. and a contact time with water of 1 hour or more. <Tensile strength> Measured according to JIS P 8113-98. <Wet tensile strength> It was measured according to JIS P 8135-98. <Disintegration> 1 cm x 1 cm for 800 ml of water
Was put into a household mixer and stirred for 2 minutes. A hand-made sheet having a basis weight of 100 g / m ² was prepared from the obtained pulp slurry. If the size of defibrated pieces of undisintegrated material is 1 mm x 1 mm or less,
m × 1 mm to 5 mm × 5 mm, Δ: 5 mm × 5 mm or more <Water penetration from the edge>
The degree of penetration of water from the edge when immersed for 4 hours was evaluated in three stages. ○ indicates no penetration, △ indicates slight penetration,
× indicates large penetration or delamination due to penetration. <Ink setting> RI printing tester (Meiji Seisakusho)
Using ink for offset sheet-fed printing (trade name "TK
1.0 g of Hi-Echo Ink (manufactured by Toyo Ink Co., Ltd.) was spread and printed, and after 5 minutes of printing, the coated paper was adhered to the printing surface with a constant pressure, and the ink transfer state to the coated paper was evaluated in five steps. . ：: Very fast setting, capable of coping with high-speed offset sheet-fed printing, no need to increase the amount of spray powder, and no problem of set-off. ：: Fast setting, no need to increase the amount of spray powder in normal printing, and no set-off problem. Δ: Standard level. Δ ×: Set a little slower and requires more spray powder, but printable level by adjusting printing conditions. X: The setting is slow and cannot be used for offset printing. <Surface strength during printing> RI printing tester (Meiji Seisakusho)
1.0 g of special ink for surface strength measurement (trade name “SMX Tack Grade 20”, manufactured by Toyo Ink Co., Ltd.)
After printing by using, the backing was performed, and the peeling state of the paper surface was visually evaluated in three stages. ○: No peeling at all
Δ: Slight peeling but no problem. ×: Peeling occurs, causing a problem of paper dust during offset printing.

Example 2 A water-resistant printing paper was completed in exactly the same manner as in Example 1 except that the amount of the water-resistant layer applied was changed to 10 g / m ² .

Example 3 A water-resistant printing paper was completed in exactly the same manner as in Example 1 except that the coating amount of the printing layer was changed to 12 g / m ² .

Example 4 In the coating of the printing layer, polyethylene wax (trade name "Chemipearl W-300", 100 parts by weight of filler)
Waterproof printing paper was completed in exactly the same manner as in Example 1 except that 4.0 parts by weight of solid content (manufactured by Mitsui Chemicals, Inc.) was added.

Example 5 Regarding the styrene-butadiene copolymer latex of the water-resistant layer, Tg was 4 ° C., the amount of acid groups bonded or adsorbed on the surface of the styrene-butadiene copolymer and the amount of acid groups in the aqueous phase of the copolymer latex And the total amount is 1 g of copolymer in terms of hydrochloric acid equivalent.
A water-resistant printing paper was completed in exactly the same manner as in Example 1 except that latex (trade name “Nipol F8B”, Nippon Zeon Co., Ltd.) having an equivalent weight of 0.15 milligram was used.

COMPARATIVE EXAMPLE 1 The base paper used in Example 1 was modified rosin emulsion sizing agent (trade name "Size Pine N-771", Arakawa Chemical Co., Ltd.) among the chemicals added to the raw material in the mixing tank. 0.5% in terms of solid content per pulp weight, and a wet strength agent (trade name “WS-54”) was added.
7 "(manufactured by Nippon PMC Co., Ltd.) was added in the same manner as in Example 1 except that the solid content concentration was 1.2% to complete a water-resistant printing paper.

Comparative Example 2 A water-resistant printing paper was completed in exactly the same manner as in Example 1 except that the coating amount of the water-resistant layer was changed to ² g / m ² .

Comparative Example 3 A water-resistant printing paper was completed in exactly the same manner as in Example 1, except that the coating amount of the water-resistant layer was changed to 15 g / m ² .

Comparative Example 4 Example 1 except that the coating amount of the printing layer was changed to 3 g / m ^2.
A water-resistant printing paper was completed in exactly the same manner as described above.

Comparative Example 5 A water-resistant printing paper was completed in exactly the same manner as in Example 1 except that the coating amount of the printing layer was changed to 18 g / m ² .

Comparative Example 6 The styrene-butadiene copolymer latex of the water-resistant layer was completely the same as Example 1 except that a latex having a Tg of -15 ° C. (trade name “Nipol F8B” Nippon Zeon Co., Ltd.) was used. Similarly, water-resistant printing paper was completed. Water-resistant printing paper was completed in the same manner as in Example 1 using the water-resistant layer.

Comparative Example 7 The styrene-butadiene copolymer latex of the water-resistant layer was exactly the same as Example 1 except that a latex having a Tg of 57 ° C. (trade name “Nipol F8B”, Nippon Zeon Co., Ltd.) was used. Thus, a waterproof printing paper was completed. Water-resistant printing paper was completed in the same manner as in Example 1 using the water-resistant layer.

[0042]

The evaluation results of the examples and the comparative examples are shown in Table 1. From the results of Examples 1 to 5, the amounts of the wet strength agent and the sizing agent to be added to the base paper are appropriate, and the water-resistant paint and the print paint as specified in the present invention are applied in the specified amounts. Water temperature 30 ° C, contact time 1
The water absorption of Cobb in time is less than 10 g / m ² , the decrease in wet tensile strength relative to the dry tensile strength is small, the disintegration is good, there is almost no penetration of water from the edge, and the ink setting property and It was confirmed that water-resistant printing paper having excellent printability such as surface strength when dried was obtained.

On the other hand, when the base paper is manufactured from the results of Comparative Example 1, if the amount of the wet paper strength enhancer added to the raw material is too large or the amount of the sizing agent is too small, the present invention is not improved. However, the disintegration property, which is a major feature of the paper, is deteriorated, and the paper cannot be reused as used paper, or delamination occurs due to penetration of water from the edge.

As can be seen from the results of Comparative Example 2,
If the coating amount of the water-resistant layer is less than the specified amount, water easily penetrates, and not only does the water absorption of the cobb significantly increase, but also the decrease in wet tensile strength relative to dry tensile strength increases. Conversely, when the coating amount of the water-resistant layer is larger than the specified amount as in Comparative Example 3, the disintegration property is deteriorated, and the ink setting property largely related to the printing workability is deteriorated.

When the coating amount of the printing layer is less than the specified amount as in Comparative Example 4, the ink setting property is deteriorated, and the ink cannot be used in normal offset printing.

When the coating amount of the printing layer is larger than the specified amount as in Comparative Example 5, the ink setting property is very good, but the surface strength is remarkably deteriorated, and when offset printing is performed, paper dust trouble occurs. . In addition, the penetration of water is slightly increased, and the decrease in wet tensile strength is also slightly increased.

As in Comparative Example 6, when the glass transition temperature of the styrene-butadiene copolymer latex used in the water-resistant layer is lower than the specified temperature, water seepage decreases, but the disintegration property deteriorates and the paper is reused as used paper. become unable. Further, although not shown in this evaluation, even if the printing layer is applied, a sticky feeling on the surface may occur and blocking may occur when the film is wound up.

If the glass transition temperature of the styrene-butadiene copolymer latex is higher than the specified temperature, the film resistance of the water-resistant layer becomes poor, and the water absorption of Cobb becomes extremely large.
The decrease in wet tensile strength relative to dry tensile strength is large. Further, the penetration of water from the edge is also poor.

As described above, it was confirmed that the desired water-resistant printing paper can be obtained by sequentially applying the water-resistant layer and the printing layer as defined in the present invention to paper having good disaggregation and strong size. .

[0050]

[Table 1]

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 2H113 AA03 BA05 BB02 BB22 BB33 DA46 DA47 DA63 EA03 EA10 EA19 FA06 FA10 FA10 4J038 CA041 CC041 DF002 KA08 MA08 MA10 MA13 NA04 PB11 PC10 4L055 AA02 AA03 AC06 AG08 AG10 AG19 AG AG87 AG89 AG97 AH11 AH16 AH37 EA10 EA14 EA20 EA29 EA32 FA15 FA19 GA19

Claims (4)

[Claims] 1. A coated paper comprising a paper support having a water-resistant layer and a printing layer sequentially provided on both sides thereof, wherein the water-resistant layer has a temperature of -10 to 50 ° C.
Composed of styrene-butadiene copolymer latex having a glass transition temperature of 3 to 12 g / m2.
² , the printing layer was a filler-coated layer, and among 100 parts by weight of the filler, 10 to 4 fillers having an oil absorption of 100 to 300 ml / 100 g measured according to JIS K 5101.
0 parts by weight, the coating amount is 5 to 15 g / m ² , and the water absorption of the cobb measured according to JIS P 8140-98 (humidity control conditions of the sample: 30 ° C., 80% R
H 24 hours or more, test water temperature: 30 ° C, contact time with water:
(1 hour) is 30 g / m ² or less. 2. The sum of the amount of acid groups bound or adsorbed on the surface of the styrene-butadiene copolymer constituting the water-resistant layer and the amount of acid groups in the aqueous phase of the copolymer latex is expressed in terms of hydrochloric acid equivalent. The water-resistant printing paper according to claim 1, wherein the amount of the water-resistant printing paper is 0.4 to 3.5 milligram equivalent per gram of the polymer. 3. A polyamide-polyamine-epichlorohydrin resin is added in an amount of 0.8 parts by weight or less as a solid content to 100 parts by weight of pulp used as a papermaking raw material in producing a paper support. The water-resistant printing paper according to claim 1, wherein the agent is added in an amount of 0.8 to 2.0 parts by weight in terms of solid content. 4. The water-resistant printing paper according to claim 1, wherein 2 to 8 parts by weight of a solid content of polyethylene oxide is added to 100 parts by weight of the filler in the coating material of the printing layer.