JP4675112B2 - Carton base paper with improved ruled line cracking characteristics and printing effect - Google Patents

Description

The present invention relates to a multi-layer carton base paper. More specifically, the present invention improves the color of the printing ink by maintaining the specific hue of the carton base paper (improving the printing effect). When the carton base paper is processed into a tissue paper box, the inside tissue paper becomes white. The present invention relates to a carton base paper having improved ruled line cracking characteristics that looks beautiful (improves appearance and aesthetic effect) and is easily chamfered by improving the carton ruled line cracking characteristics.

Carton base paper, especially multi-layer base paper processed into tissue paper boxes, generally uses kraft pulp with the top layer (also referred to as surface layer) bleached, but it is taken out from recent nature-oriented and environmental considerations. Cartons without a film on the mouth have been proposed, but white materials have still been used as the surface layer of the base paper for beautiful printing, advertising, advertising claims, and visual appeal to customers.

Due to the above-mentioned background, so-called unprinted or unprinted tissue paper boxes that use semi-bleached kraft pulp for the front and back layers of the base paper have been proposed and sold recently, but the design is poor. Due to the difficulty of characterization, there is still a demand for a multi-layer carton base paper having a natural color tone that has excellent ink color development that attracts the eyes of printed customers.

Regarding the paperboard, it is known to manufacture a paperboard to make paper by adding a cationic surfactant containing at least one alkyl group having 12 to 24 carbon atoms or alkylyl group in the molecule to the pulp slurry as an improvement in ruled line cracking. (Patent Document 1).

It has been proposed to express the characteristics of paper as surface reflection characteristics. For example, in the case of electrophotographic transfer paper, since the color tone of the original image transferred by the copying machine accurately reproduces the color tone of the original plate, L * ≧ 90, a * = + 4 to −2, b * = + 2 to −9. (Patent Document 2 and Patent Document 3), the surface to which the receiving layer is applied in order to maintain the whiteness deterioration of the image receiving layer over time and the sharpness of the image over a long period of time as the thermal transfer paper The surface reflection characteristics of L, a, and b when measured by the method defined in JIS Z 8722 and displayed by the method defined in JIS Z 8730 are L = 90 or more and a = −1. It has been proposed to be in the range of 0 to +2.0 and b = −2.0 to −5.0 (Patent Document 4). In addition, as a lightweight coated paper, the base paper and coating layer are coated with a coloring agent, black dye, pigment, etc. in order to improve the poor visual quality and the quality of printed matter. In order to mix and make the difference between the whiteness of the base paper for coating and the whiteness of the coated paper within 6%, a * = − 5 to 0.5, b * = − 1 to 8.0 can be adjusted. It has been proposed (Patent Document 5). However, it has not been specifically proposed to express the characteristics as surface reflection characteristics in the multi-layer carton base paper.

JP-A-11-200209 Japanese Patent No. 3384394 Japanese Patent No. 3217085 Japanese Patent No. 2672317 Japanese Patent No. 2554344

The present invention is a multi-layer carton base paper having a non-white natural hue with excellent ink color development, and a multi-layer with improved ruled line cracking characteristics when processed into paper containers, packaging materials, boxes, etc. Paper cartons are provided.

In order to provide a multi-layer carton base paper having excellent ink coloring properties, the present inventors have obtained a carton base paper having excellent lightness, which is visually excellent as a result of various experiments. As a result of examining natural color tone by appropriately changing the type and amount of each colorant of blue, red and white, the surface reflection characteristics L *, a * and b * are within a predetermined range. It was found that the ink coloring property was very excellent visually.

In order to provide a multi-layer carton base paper having improved ruled line cracking characteristics when processed into paper containers, packaging materials, and boxes, the present inventors have provided factors for obtaining a carton base paper having stable improved line cracking characteristics. As a result of studying the paper, the above problem can be solved by making the uppermost layer of carton base paper mainly composed of pulp (A) and unbleached kraft pulp (B), which are beaten high-density corrugated cardboard. The present invention has been completed.

The present invention comprises the following (1) to (5) in order to solve the above problems.

(1) A multi-layer carton base paper, and the uppermost layer of pulp (A) and unbleached kraft pulp (B) beaten at a high concentration in the range of 20 to 35% by weight when the used cardboard is beaten And the reflection characteristics of the surface (display method defined in JIS Z 8729, light source: C / 2) are L * = 59.5-63.0, a * = 4.0-6. 0, b * = 19.0-21.5
A carton base paper characterized by having a freeness of the pulp (A) beaten at a high concentration of 200 to 350 ml CSF and having 10 / m ² or less dust having a diameter of 1.0 mm or more. It is.

(2) The carton base paper according to the item ( 1) , wherein the carton base paper is a multi-layer paper making of 3 to 9 layers.
(3) The carton base paper according to any one of (1) to ( 2 ), wherein the uppermost layer is further coated with a surface of polyvinyl alcohol.

(4) The carton base paper according to any one of (1) to ( 3) , wherein the Oken-type smoothness on the surface of the uppermost layer is 5 seconds or more.

(5) A tissue paper box having no film at the outlet, characterized in that the multilayer carton base paper according to any one of (1) to ( 4) is used.

In particular, the present invention improves the color developability of the printing ink by having a specific hue of natural color without using bleached pulp in the uppermost layer of the carton base paper. The paper looks white and beautiful. By eliminating the dust, there is no misreading of barcodes. Since the ruled line cracking characteristics are improved, it can be processed into any paper container, packaging material, box, etc.

The surface reflection characteristic values L *, a *, and b * of the present invention are obtained by the methods defined in JIS Z 8722 and JIS Z8729. According to this specification, three values of L *, a *, and b * are obtained. Represents the hue of the measurement object. Here, L * represents lightness, and the larger this value, the higher the lightness. Moreover, a * represents redness, and it shows that redness is so strong that a numerical value is large, and when it becomes-(minus), it shows that redness is insufficient, in other words, greenness is strong. Furthermore, b * is an index of yellowishness, and when this value is large, it indicates that yellowishness is strong, and when it is − (minus), it indicates that yellowishness is insufficient and blue. And when both a * and b * are 0, it means colorlessness.

Among the above values, L * representing lightness is not directly related to the color tone, but when L * becomes low, there is no visual “barking” in the hue. Therefore, in order to obtain a bright hue as a carton base paper, L * is preferably about 61. Since the carton base paper of the present invention is processed into a box or the like and aims at the contrast with the white of the contents, it is not preferable to increase the brightness of the uppermost layer.
In addition, it has been found that a color of printing ink is good when the a * value has a reddishness of about 5.0 and the b * value has a yellowish hue of about 20.0. It came. In addition, when the carton base paper having the hue of the present invention is used as a box of tissue paper, the whiteness of the tissue paper stands out most preferably.
Also, by eliminating the film at the outlet of the box, the white color of the tissue paper and the hue of the carton base paper can be obtained, and after the tissue paper is exhausted, it can be recovered as waste paper without being separated.
In the present invention, various colorants are added in a composite manner to the layer so that the surface reflection characteristics are within the above-mentioned range. Examples of the colorant added for this purpose include white pigments, blue dyes, yellow dyes, and red dyes. In addition to these, a fluorescent brightening agent can be added.
In the present invention, the above-mentioned colorant can be internally adjusted to the uppermost layer of the multi-layer paper and / or the surface coating is applied to the uppermost layer, thereby adjusting the value of the surface reflection characteristics as a result.

The high concentration beating in the present invention means that the pulp concentration when beating used corrugated paper is in the range of 20 to 35% by weight. According to this high-concentration beating, as compared with the usual low-concentration beating performed at 6% by weight or less, fiber cutting is reduced and fibrillation is promoted, so that the specific surface area and flexibility are increased. A pulp with improved strength, less dust, excellent printability, and good ruled line cracking properties can be obtained. When the pulp concentration is less than 20% by weight, the cracking suitability of the obtained base paper is not good, and when it exceeds 35% by weight, the fluidity of the pulp slurry is lowered and stable beating is difficult. Become. The high-concentration pulp targeted by the present invention is a pulp obtained by squeezing cardboard waste paper pulp obtained after disaggregation and selection with a pulper using a pulp watering device such as a thickener or screw press. The used corrugated paper targeted by the present invention can be a mixture of brown to yellow used paper such as unbleached kraft bags and telephone bags in addition to ordinary used corrugated cardboard boxes. The freeness of the corrugated waste paper pulp (A) beaten at high concentration in the present invention needs to be in the range of 200 to 350 ml CSF. If it is less than 200 ml CSF, the dewaterability in the paper making process is lowered, and if it exceeds 350 ml CSF, the above-mentioned merit obtained from high concentration beating is lowered, and the smoothness of the uppermost layer surface of the multi-layer carton base paper is lowered.

In the present invention, the corrugated waste paper pulp (A) and unbleached kraft pulp (B) beaten at a high concentration are mainly used for the uppermost layer of the multi-layer carton base paper. In this invention, it is preferable to use unbleached kraft pulp (B) so that content may become 30-60 absolute dry weight%. When the blending amount exceeds 60% by dry weight, the base paper is not uniform and the surface property of the base paper is changed, so that the printability is deteriorated. As the dust characteristic observed on the surface of the uppermost layer composed of the pulps (A) and (B), it is preferable that dust having a diameter of 1.0 mm or more is 10 pieces / m ² or less. When the number of dust particles exceeds 10 / m ² , when used as a paper container, packaging material, or box on which a barcode is printed, it may cause misreading during barcode reading.

The multilayer carton base paper of the present invention is made by making the above pulps (A) and (B) together with a multilayer paper machine so as to be the uppermost layer. The number of layers to be combined is preferably 3 to 9 layers including the uppermost layer. In the case of single-layer or double-layer papermaking, when a ruled line is put in a box for use as a paper container, the bending stress is not relieved and the ruled line cracks. In the case of 3 layers or more, peeling between the layers is caused and ruled line cracking is reduced. With 10 layers or more, the floor area of each layer is too small, and virtually no paper can be made. The pulp of the layers other than the top layer of the multi-layer carton base paper of the present invention may be the pulp used for the top layer, or pulp obtained by disaggregating recovered waste paper such as magazine waste paper and newspaper waste paper. There is no particular limitation like virgin pulp such as blackened pulp and bleached kraft pulp. In papermaking, other known internal chemicals such as sizing agents such as rosin and alkyl ketene dimer, paper strength enhancing agents such as polyacrylamide and starch, pH adjusting agents such as sulfuric acid band, and the like can be appropriately used. Further, the ruled line cracking property is further improved by spraying interlayer starch or interlayer paper strength agent between the uppermost layer and the other layers.

The multi-layer carton base paper of the present invention is made by applying a surface of polyvinyl alcohol (hereinafter abbreviated as PVA) to the uppermost layer of the paper made as described above. The surface coating method may be any facility that is usually employed, such as a bar coater, rod metering coater, blade coater, gravure coater, roll coater, air knife coater, water doctor attached to a machine calendar, etc. It is done. It is preferable that the coating amount of the polyvinyl alcohol of the present invention is 0.1 to 0.5 g / m ² in terms of solid content weight. When the coating amount is less than 0.1 g / m ² , the surface strength of the base paper becomes insufficient, and the pulp on the top layer surface is taken during offset printing. Also, the printed ink sinks into the base paper, and the color of the printing ink is reduced. When the amount is more than 0.5 g / m ² , the base paper is stained and the appearance is deteriorated.

In the multi-layer carton base paper of the present invention, the Oken-type smoothness of the surface of the uppermost layer is preferably 5 seconds or more, and when it is less than 5 seconds, the machine calender and / or gloss calender installed in the paper machine is used. Smoothing is performed. When the Oken type smoothness is less than 5 seconds, ink is not printed on the paper when offset printing is performed, and white spots occur. In particular, since this defect becomes remarkable at the time of gravure printing, papermaking is performed by determining the number of nips of the calendar, the linear pressure, etc. according to the required smoothness.

The multi-layer carton base paper of the present invention is often used as a paper container, packaging material, or box, and has a rice basis weight of 230 to 600 g / m ² . Especially when using it as a box of tissue paper, 370 g / m ^{2 of} rice tsubo and a thickness of 460 μm are commonly used.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited at all by these Examples. In addition,% in an Example and a comparative example shows weight% unless there is particular notice. The evaluations and evaluation methods performed in the examples and comparative examples are as follows.

(1) Freeness (also called Canadian standard freeness): According to JIS P 8121.
(2) US tsubo: According to JIS P 8124.
(3) Thickness: According to JIS P 8118.
(4) Hue: According to JIS Z 8729.
(5) Chile: The number of dust per 1 m ^{2 having a} diameter of 1.0 mm or more is visually measured. Conforms to JIS P 8145.
(6) Smoothness: JAPAN TAPPI Paper Pulp Test Method No. According to 5-2.
(7) Ink blank area: Using an magenta process ink with an RI printing machine, offset printing was performed with a supply ink amount of 0.5 cc, and the blank area on the top layer surface was visually evaluated.
(8) Ink color development: Using an magenta process ink with an RI printer, offset printing was performed with a supplied ink amount of 0.25 cc, and the color development of the ink was visually evaluated.
(9) Ruled line crack length ratio: A sample dried to a completely dry state with a dryer was folded in half with the uppermost surface facing outward, set to a predetermined clearance, and pressurized using a lab mini-calendar . The crack length of this folded part was measured, and the crack length ratio was determined from the following formula.
Crack length ratio (%) = [cracked length (mm) / total length of the folded part (mm)] × 100
(10) Picking: JAPAN TAPPI Paper Pulp Test Method No. According to 1.

<Example 1>
Using a love flaker type DDR (Love Flaker 42 type: manufactured by Aikawa Tekko Co., Ltd.), pulp (A) obtained by beating pulp waste paper pulp obtained after pulping and fine selection with a pulper so that the pulp concentration is 25% by weight and the freeness is 300 ml CSF. A solution containing pulp (A) / pulp (B) containing a solution containing pulp (B), which was normally beaten to give a freeness of 500 ml CSF with an unbleached kraft pulp of softwood at a pulp concentration of 4% by weight Mixing was performed so that the absolute dry weight ratio was 60/40 to obtain a pulp slurry for the uppermost layer. To the obtained uppermost layer pulp slurry, a sulfuric acid band was added so that the slurry pH was 5.0, and 200 g of yellow dye and 500 g of red dye were added per pulp ton. The upper layer was used. The other layers were made using corrugated waste paper pulp that was normally beaten to a freeness of 300 ml CSF at a pulp concentration of 4% by weight. Next, an aqueous polyvinyl alcohol solution (Povar VF-17: manufactured by Nippon Vinegar Poval Co., Ltd.) is added to the water doctor of the machine calendar, and the surface of the uppermost layer is polyvinyl alcohol so that the solid content concentration is 0.15 g / m ^2. At the same time, a calendar process was performed. At this time, the application amount of the top layer was 50 g / m ² , and the other layers were 8 layers, and a total of 9 layers of paper basis 368 g / m ² multilayer paper carton paper was obtained.
The obtained base paper was used to evaluate the hue, dust, smoothness, ink blank, color developability, ruled line crack length ratio, and picking on the surface of the uppermost layer. Table 1 shows the papermaking conditions and the results of quality evaluation.

<Example 2>
In the same manner as in Example 1 except that magazine waste paper pulp normally beaten so as to have a freeness of 330 ml CSF was used for the other layers, a total of 9 layers of multi-ply carton with a basis weight of 353 g / m ² was obtained. However, the application amount of the uppermost layer was 50 g / m ² and the addition amounts of the yellow dye and the red dye were increased so that the hue of the uppermost layer was within a predetermined range. The same items as in Example 1 were measured and evaluated.

<Example 3>
Except for the freeness of high-concentrated corrugated waste paper pulp (A) is 350 ml CSF, the top layer is 100 g / m ² , the other layers are 2 layers, and the total weight is 364 g / m ² Produced a carton base paper in the same manner as in Example 1. The same items as in Example 1 were measured and evaluated.

<Comparative Example 1>
In the same manner as in Example 1 except that the freeness of the corrugated waste paper pulp (A) beaten at a high concentration was changed to 420 ml CSF, a 9-ply 369 g / m ² multi-ply carton base paper was obtained. The same items as in Example 1 were measured and evaluated.

<Comparative Example 2>
Dissolved and carefully selected corrugated waste paper pulp with a pulp concentration of 4% by weight and normally beaten to a freeness of 480 ml CSF is used in place of the pulp (A) of Example 1, and the top layer weight is 150 g / m. ^The other layers were 1 layer, and a carton base paper having a total weight of 350 g / m ² was obtained in the same manner as in Example 1 except that a total of two layers were made. The same items as in Example 1 were measured and evaluated.

<Comparative Example 3>
After the paper making, a multi-layer carton base paper having a total weight of 360 g / m ² and a total of 9 layers was made in the same manner as in Example 1 except that the obtained paper base was not coated with polyvinyl alcohol and calendered. Got. The same items as in Example 1 were measured and evaluated.

<Comparative example 4>
As the uppermost layer of pulp slurry, a total of 9 layers of rice basis weight of 374 g / m ² is obtained in the same manner as in Example 1 except that the absolute dry weight ratio of pulp (A) / pulp (B) is 30/70. A multi-layer carton base paper was obtained. The same items as in Example 1 were measured and evaluated.

The evaluation results of Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1.
In Examples 1 to 3, good evaluation results are shown. On the other hand, Comparative Example 1 is inferior in dust, white ink, and ruled line crack length. In Comparative Example 2, since the two-layer paper making, the ink whitening and the ruled line cracking length are significantly inferior. In Comparative Example 3, since the polyvinyl alcohol is not coated and calendering is not performed, the smoothness is low, the ink whiteness and the color developability are inferior, and the surface strength is also inferior. In Comparative Example 4, since it was not within the predetermined hue range, the coloration applied to vividness was shown.

<Example 4>
When the tissue paper box was produced using the carton base paper obtained in Example 1, it could be processed without any particular ingenuity in the ruled line shape, and no ruled line cracking occurred. In particular, by removing the film at the outlet, the whiteness of tissue paper and the color of the carton base paper became vivid.

The multi-layer carton base paper of the present invention can be used as a paper container, packaging material, box, and the like, in particular, a tissue paper box having no film at the outlet.

Claims (5)

A multi-layer carton base paper, the uppermost layer of which is mainly pulp (A) and unbleached kraft pulp (B) beaten at a high concentration in the range of 20 to 35% by weight when the used cardboard is beaten. The reflection characteristics of the surface (display method defined in JIS Z 8729, light source: C / 2) are L * = 59.5-63.0, a * = 4.0-6.0, b * = 19.0 to 21.5
A carton base paper characterized by having a freeness of the pulp (A) beaten at a high concentration of 200 to 350 ml CSF and having 10 / m ² or less dust having a diameter of 1.0 mm or more. . The carton base paper according to claim 1 , wherein the carton base paper is a multi-layered paper having 3 to 9 layers. 3. The carton base paper according to claim 1, wherein the uppermost layer is further coated with polyvinyl alcohol. The carton base paper according to any one of claims 1 to 3 , wherein the Oken-type smoothness of the surface of the uppermost layer is 5 seconds or more. A box of tissue paper having no outlet film, characterized in that the multi-layer carton base paper according to any one of claims 1 to 4 is used.