JP2008038287A - Both side colored multi-layered paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide both side colored multi-layered paper whose front and back sides are adjusted in an identical color, and which has excellent appearances from the front and back sides even in the case of both side-dark colored multi-layered paper, has high interlayer strength, and can be produced at a low cost. <P>SOLUTION: In the both side colored multi-layered paper having a basis weight of 70 to 150 g/m<SP>2</SP>, a colorant is added to raw material pulp for a front side layer and a back side layer to adjust the luminosity (L values) of the front layer side and the back layer side to ≤53, the hue (a values) of the front layer side and the back layer side to a range of -33 to 33, and the tone of the front layer side and the hue of the back layer side to the same extent, and the luminosity (L values) of an intermediate layer is adjusted to -40≤L1-L2≤-8, wherein L1 is the luminosity of the front layer side and the back layer side, and L2 is the luminosity of the intermediate layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention adjusts the front and back surfaces to substantially the same color, and is a multi-layered double-sided colored paper with particularly low lightness, excellent appearance from the front and back surfaces, high interlayer strength, and manufacturing cost. The present invention relates to a multi-layered double-sided colored paper having a low image quality.

  Conventionally, as a paper used as a fancy paper used in catalogs, book covers, flips, paper containers, etc., thick single-layer papers or multilayer papers colored with dyes or pigments have been used.

  General multi-layer paper is manufactured by mixing a large amount of waste paper pulp in the intermediate layer, but when the above-mentioned single-layer paper or multi-layer paper is used as fancy paper, it has a particularly excellent high-class feeling, surface Because the appearance of the back side and the side (cross section) are required, virgin pulp is used for the intermediate layer, and not only the front and back layer raw pulp, but also the intermediate layer raw pulp as well as the front and back layers A coloring agent such as a pigment is added to adjust all layers to the same color tone.

  For this reason, the conventional multi-layer paper used as fancy paper is very expensive and cannot be mixed with a large amount of waste paper pulp, so it is not suitable for the recent environmental problems and resource saving.

  Some of the papers that use multi-layered paper made of waste paper pulp as the intermediate pulp are used as fancy paper. However, in order to maintain a high-grade feeling and appearance, such multilayer paper also uses bleached waste paper pulp or white paper waste pulp having a high degree of whiteness, and the raw material pulp of the intermediate layer is also the front and back layers. In the same way as above, colorants such as dyes and pigments are added to adjust all layers to the same color tone. Therefore, compared with single-layer paper, the manufacturing cost is reduced in that the waste paper pulp is used for the intermediate layer, but it is slight.

  Therefore, as shown in Patent Document 1, the present applicant, while maintaining the appearance, maintains the appearance of the surface layer in order to achieve both of the contradictory relationships of improvement in quality such as appearance and reduction in manufacturing cost. We are proposing colored paperboard with reduced basis weight to reduce costs.

That is, (1) The color tone of the surface layer is adjusted by a colorant added to the raw material pulp of the surface layer, and the color tone of the surface layer is adjusted by using white water generated in the surface layer making as dilution water of the raw material pulp of the surface layer. (2) Surface color tone (L, a, b), surface color tone (L1, a1, b1), and −20 <L-L1 <0, (3) surface layer basis weight the 10 to 30 g / m ^2, such as by the basis weight of the table lower layer 10 g / m ² or more, the production method and colored colored paperboard which attained by reducing the basis weight of the surface layer lower cost while maintaining the visual quality A paperboard is disclosed.

  However, the fancy paper used in catalogs, book covers, flips, paper containers, etc., has a wide variety of color tones from light to dark, from red to green, from yellow to blue. Variety.

  For this reason, by applying the technique of Patent Document 1 to a multi-layered double-sided colored paper, in the case of a light-colored colored paper having a high lightness (L value), it is possible to reduce the cost while maintaining the appearance. In some cases, it has been found that it becomes more difficult to reduce the cost while maintaining the appearance of dark colored paper having a lower lightness (L value).

  Further, when used in a paper container or the like, there is a case where the interlayer strength is weak as a defect of the multi-layer paper.

JP 2006-144132 A

  The present invention has been made in view of the above-described circumstances, and its object is to adjust the front and back surfaces to the same color, and particularly to provide a multi-layered double-sided colored paper having a low lightness. However, it is to provide a multi-layered double-sided colored paper that is excellent in appearance from the front and back surfaces, has high interlayer strength, and can be manufactured at low cost.

The above object of the present invention is to provide a multilayer paper having a basis weight of 70 to 150 g / m ² having at least a surface layer, a back layer, and an intermediate layer composed of one or more layers disposed between the surface layer and the back layer. Double-sided colored paper,
The color tone of the surface layer and the back layer is obtained by adding a colorant to the raw material pulp of the surface layer and the back layer.
The brightness (L value) of the surface of the surface layer and the back surface of the back layer is 53 or less,
The hue (a value) of the surface of the surface layer and the back surface of the back layer is in the range of −33 to 33, and the color tone of the surface of the surface layer and the color tone of the back surface of the back layer are adjusted to be approximately the same. And
The lightness (L value) of the intermediate layer is adjusted to −40 ≦ L1−L2 ≦ −8, where L1 is the lightness of the front surface and the back surface of the back layer, and L2 is the lightness of the intermediate layer. This is achieved by providing a multilayered double-sided colored paper characterized by

The above-mentioned object of the present invention can be effectively achieved by providing a multilayered double-sided colored paper characterized in that the amount of each of the surface layer and the back layer is 25 to 50 g / m ^2. The

  Further, the object of the present invention is to set −15 ≦ a1−a2 ≦ 25 and −32 ≦ b1 where the hues of the front surface and the back surface are (a1, b1) and the hue of the intermediate layer is (a2, b2). This is achieved more effectively by providing a multilayered double-sided colored paper characterized in that -b2≤20.

  Further, the above object of the present invention is to contain at least 10 to 50% by mass of softwood pulp in each raw material pulp of the surface layer and the back layer, and at least a paper strength enhancer in the surface layer and the back layer. Is achieved more effectively by providing a multilayered double-sided colored paper characterized by containing 0.1 to 1.2% by mass in solid content of each raw material pulp.

  Furthermore, the above-mentioned object of the present invention is to add white water produced by papermaking of the surface layer and the back layer to white water of the intermediate layer, thereby coloring the raw pulp of the intermediate layer. This is achieved more effectively by providing a double-sided colored paper.

According to the multi-layered double-sided colored paper according to the present invention, the color tone of the surface layer and the back layer can be adjusted by adding a colorant to the surface layer and the back layer raw material pulp so that the brightness (L Value) 53 or less, the hue (a value) of the surface of the front layer and the back surface of the back layer is in the range of −33 to 33, and the color tone of the surface of the surface layer is the same as the color tone of the back surface of the back layer. Since the brightness (L value) of the intermediate layer was adjusted to −40 ≦ L1−L2 ≦ −8 with the brightness of the front surface and the back surface of the back layer being L1, and the brightness of the intermediate layer being L2, both sides of the multi-layer paper making The surface of the colored paper is excellent in appearance and the back surface, and even the paper having a basis weight of 70 to 150 g / m ² is excellent in appearance from the side surface in the thickness direction.

In addition, since the amount of each of the surface layer and the back layer is set to 25 to 50 g / m ² , the surface / back surface appearance and the side surface appearance are excellent, and the manufacturing cost and quality can be efficiently obtained in a balanced manner. .

  Moreover, since the hues of the front and back surfaces are (a1, b1) and the hues of the intermediate layer are (a2, b2), and −15 ≦ a1-a2 ≦ 25 and −32 ≦ b1-b2 ≦ 20, It is superior in the appearance of the back surface and the appearance of the side surface, and it is possible to efficiently obtain the manufacturing cost and quality in a balanced manner.

  Moreover, 10-50 mass% of softwood pulp is contained in the raw material pulp of at least the front layer and the back layer, and a paper strength enhancer is added to the pulp of each layer in a solid content of 0.1 to 1.2 at least in the front layer and the back layer. Since it is contained by mass%, delamination does not occur during processing and use.

  Furthermore, white water produced by the surface layer and back layer papermaking is mixed with the white water of the intermediate layer to color the raw pulp of the intermediate layer, so a separate colorant for obtaining the color tone of the raw pulp of the intermediate layer is required. In addition, the manufacturing cost can be further reduced.

  Hereinafter, the multi-layered double-sided colored paper according to the present invention will be described in detail by taking, as an example, a case where it is composed of three paper layers, a surface layer, an intermediate layer, and a back layer. The multi-layered double-sided colored paper according to the present invention is not limited to the following embodiments, and it goes without saying that the configuration can be changed as appropriate without departing from the scope of the claims.

  As shown in FIG. 1, a multilayer double-sided colored paper (hereinafter referred to as “main colored paper”) 10 according to the present invention is composed of three paper layers, a surface layer 11, an intermediate layer 12, and a back layer 13. Has been.

  The surface layer 11 and the back layer 13 of the colored paper 10 are: (a) good surface / back surface appearance, side surface appearance, (b) high quality, (c) good texture, (d) printability, (e ) This layer is responsible for ensuring the surface strength.

  Therefore, the surface layer 11 and the back layer 13 of the colored paper 10 can be produced by the same method as that for a general multilayer paperboard. However, since the main use object of the colored paper 10 is so-called fancy paper used for catalogs, book covers, flips, paper containers, etc., the surface layer 11 and the back layer 13 are the above-mentioned (a) to (e ) And the like, the color tone of the surface layer 11 and the back layer 13 is obtained by adding a colorant to the raw material pulp of the surface layer 11 and the back layer 13 so that the surface of the surface layer 11 and the back surface of the back layer 13 are The lightness (L value) is 53 or less, the hue (a value) of the surface of the surface layer 11 and the back surface of the back layer 13 is in the range of −33 to 33, and the color tone of the surface of the surface layer 11 and the back layer 13 Adjustment is made so that the color tone of the back surface is about the same (substantially the same color). In this specification, the surface of the surface layer 11 (hereinafter, also simply referred to as “surface”) refers to the surface of the surface layer 11 that is not in contact with the intermediate layer 12, and the back surface of the back layer 13 (hereinafter simply referred to as “surface”). The “back surface” is also referred to as the surface of the back layer 13 that is not in contact with the intermediate layer 12.

  That is, the surface layer 11 and the back layer 13 of the colored paper 10 are colored by internally adding a colorant to each raw material pulp of the surface layer 11 and the back layer 13, and the color tone of the surface layer 11 and the back layer 13 are approximately the same. Adjust as follows.

  Here, as the colorant, for example, various known colorants such as a basic dye, a dye such as a cationic dye and a direct dye, and a color pigment composed of an inorganic pigment or an organic pigment can be used.

  The surface layer 11 and the back layer 13 of the present colored paper 10 are adjusted by a colorant so that the color tones are the same. Specifically, the lightness (L of the surface of the surface layer 11 and the back surface of the back layer 13 (L Value) is 53 or less, and the hue (a value) of the surface of the surface layer 11 and the back surface of the back layer 13 is adjusted to be in the range of −33 to 33.

  That is, when the lightness (L value) of the surface of the surface layer 11 and the back surface of the back layer 13 exceeds 53, the fancy paper formed using such colored paper has a relatively light color tone. . In such a case, the appearance from the surface of the surface layer 11 (hereinafter referred to as “surface appearance”) and the appearance from the back surface of the back layer 13 (hereinafter referred to as “back surface appearance”) are good. In order to achieve this, it is necessary to use expensive white waste paper in the middle layer 12 with a high blending ratio of 70% or more, and all layers should be substantially the same color, or the amount of each of the surface layer 11 and the back layer 13 can be increased. However, the manufacturing cost cannot be reduced.

  In addition, when the hue (a value) of the surface of the surface layer 11 and the back surface of the back layer 13 is less than −33 or exceeds 33, the color tone is a vivid dark green system or a vivid dark red system. Become. In such a case, the appearance of the front and back surfaces is degraded. Even in such a case, in order to prevent the vividness from being deteriorated, it is necessary to use expensive white-based waste paper with a high blending ratio of 70% or more for the intermediate layer 12 as described above, and the entire layers have substantially the same color. Or, since it is better in appearance to increase the amount of each of the surface layer 11 and the back layer 13, the manufacturing cost cannot be reduced.

With the amount of each layer of the surface layer 11 and back layer 13 is preferably set to 25 to 50 g / ^{m 2,} and more preferably a 31~40g / ^{m 2.}

The colored paper 10 has a so-called dark color tone with a lightness (L value) of 53 or less on the surface of the surface layer 11 and the back surface of the back layer 13, but the applied amount of the surface layer 11 or the back layer 13 is less than 25 g / m ^2. In this case, since the thickness of the surface layer 11 or the back layer 13 is inevitably thin, it becomes difficult to obtain a deep color tone, which is a characteristic of the dark color system. Therefore, the intermediate layer 12 also needs to be colored in the same dark color system as the surface layer 11 and the back layer 13. Therefore, since the amount of the coloring agent such as a very expensive dye is increased, the production cost of the colored paper is increased, the production cost is reduced, and the functions of (a) to (e) are achieved. It becomes difficult to achieve a desired purpose.

  In the case of colored paper having a light color tone with high lightness and a deep color tone that is not so required, the amount of each of the surface layer 11 and the back layer 13 can be reduced as much as possible.

On the other hand, when the basis weight of the surface layer 11 and / or the back layer 13 exceeds 50 g / m ² , the thickness of the surface layer 11 or the back layer 13 inevitably increases, so that it is easy to obtain a deep dark color tone. However, since the basis weight of the colored paper is almost determined, the amount of the intermediate layer 12 is inevitably reduced. For this reason, the difference with the paper comprised with a single layer, and the conventional colored paper which colored the surface layer 11, the intermediate | middle layer 12, and the back layer 13 in substantially the same color decreases, and it becomes difficult to acquire the effect peculiar to this invention. . Although it is possible to increase the applied amount of the intermediate layer 12, problems such as an increase in basis weight of the entire colored paper and an increase in manufacturing cost occur, which is not practical.

  Examples of the raw material pulp for the surface layer 11 or the back layer 13 include hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), conifer unbleached kraft pulp (NUKP), Chemical pulp such as hardwood semi-bleached kraft pulp (LSBKP), conifer semi-bleached kraft pulp (NSBKP), hardwood sulfite pulp, conifer sulfite pulp, stone grand pulp (SGP), pressurized stone grand pulp (PGW), refiner ground pulp ( RGP), Thermo Grand Pulp (TGP), Chemi Grand Pulp (CGP), Crushed Wood Pulp (GP), Thermomechanical Pulp (TMP) and other mechanical pulp, tea waste paper, craft envelope waste paper, magazine waste paper, newspaper waste paper, leaflet waste paper, Office waste paper, cardboard waste paper, Non-wood fiber such as kraft, hemp, cocoon, etc. Various known pulps such as pulps chemically or mechanically produced from can be used.

  However, when the colored paper 10 is used for a paper container or a book turnover, when the fancy paper is subjected to a turning load, the occurrence of delamination is prevented, and as a raw material pulp for the intermediate layer 12 described later, In order to make it possible to use inexpensive waste paper pulp, the softwood pulp is contained in an amount of 10 to 50% by mass, preferably 15 to 40% by mass.

  The content of softwood pulp being less than 10% by mass means that the content of hardwood pulp and mechanical pulp having a short fiber length and low strength is increased. For this reason, although the colored paper has a good texture, delamination may occur when a folding load is applied to the fancy paper formed using the colored paper.

  On the other hand, if the content of softwood pulp exceeds 50% by mass, the interlaminar strength can be improved and the occurrence of delamination can be prevented, but the texture deteriorates. In addition, it may be difficult to obtain the appearance from the side surface (cross section) (hereinafter referred to as “side appearance”).

  Next, the intermediate layer 12 will be described.

  The colored paper 10 has a single intermediate layer 12 as shown in FIG. When the colored paper 10 is used as fancy paper, the intermediate layer 12 serves as a base for efficiently ensuring good surface / back surface appearance, side surface appearance, luxury, and good texture. It is a layer that bears.

  That is, since the fancy paper is required to have a very good appearance, the colored paper 10 used for the fancy paper can be obtained even if the color tone or texture of the surface layer 11 or the back layer 13 is appropriately adjusted. If the color and texture of the paper are not appropriate, it will be difficult to obtain a good appearance as fancy paper.

  Therefore, the lightness (L value) of the intermediate layer 12 is −40 ≦ L1−L2 ≦ −8 when the lightness of the front surface 11 and the back surface of the back layer 13 is L1, and the lightness of the intermediate layer 12 is L2. Adjust so that

As a result, a large amount of waste paper pulp is blended in the raw material pulp of the intermediate layer 12, and the lightness (L1) of the surface layer 11 and the back surface of the back layer 13 is 53 or less, and the dark colored colored paper 10 is used as fancy paper. Even the front and back look is excellent. Further, as will be described later, even when the basis weight of the colored paper 10 is in the range of 70 to 150 g / m ² , the side appearance of the colored paper 10 is excellent.

  When [L1-L2] is less than −40, the difference in brightness between the brightness (L1) of the front surface or the back surface and the brightness (L2) of the intermediate layer 12 exceeds 40. In such a case, the brightness difference between the surface of the surface layer 11 or the back surface of the back layer 13 and the intermediate layer 12 becomes too large, making it difficult to obtain a deep color tone. In addition, the appearance and the side appearance of the colored paper 10 are deteriorated.

  Moreover, [L1-L2] exceeds -8 is a case where the lightness difference of the lightness (L1) of the surface or back surface and the lightness (L2) of the intermediate layer 12 is less than 8. In such a case, it is necessary to bring the lightness (L2) of the intermediate layer 12 close to the lightness (L1) of the front surface or the back surface. For this reason, a large amount of an expensive colorant such as a dye is also added to the intermediate layer 12. There is a need. Therefore, although it is excellent in the appearance of the front and back surfaces of the colored paper 10 and in the appearance of the side, it is impossible to efficiently obtain the opposite manufacturing cost and quality in a balanced manner.

  Further, the hue of the intermediate layer 12 (a value (redness), b value (yellowishness)), the hue of the surface of the surface layer 11 and the back surface of the back layer 13 (a1, b1), and the hue of the intermediate layer 12 ( In the case of a2, b2), it is preferable to adjust so that −15 ≦ a1−a2 ≦ 25 and −32 ≦ b1−b2 ≦ 20.

  Thereby, the front and back surface appearance and the side surface appearance of the colored paper 10 can be improved. Moreover, it is possible to efficiently obtain the manufacturing cost and the quality with a better balance.

  When [a1-a2] is less than −15, the hue difference between the hue (a1) of the front or back surface and the hue (a2) of the intermediate layer 12 exceeds 15, and the surface layer 11 or the back layer 13 This is a case where the reddishness of the mid layer 12 becomes stronger than the reddishness. Accordingly, it becomes difficult to obtain a deep dark color tone, and the appearance of the front and back surfaces of the colored paper and the side appearance tend to be deteriorated. In addition, due to the influence of the color tone of the intermediate layer 12 having a strong redness, the apparent color tone when the colored paper is viewed from the front surface 11 or the back surface of the back layer 13 may differ from the actual color tone. .

  On the other hand, if [a1-a2] exceeds 25, the hue difference between the hue (a1) of the front or back surface and the hue (a2) of the intermediate layer 12 exceeds 25, and the surface layer 11 or the back layer 13 This is a case where the green color of the mid layer 12 becomes stronger than the green color of. Accordingly, it becomes difficult to obtain a deep dark color tone, and the appearance of the front and back surfaces of the colored paper and the side appearance tend to be deteriorated. In addition, due to the influence of the color tone of the intermediate layer 12 that the green color is strong, the apparent color tone when the colored paper is seen from the front surface 11 or the back surface of the back layer 13 may differ from the actual color tone. .

  [B1-b2] is less than −32 means that the hue difference between the hue (b1) of the front surface or the back surface and the hue (b2) of the intermediate layer 12 exceeds 32, and the surface layer 11 or the back surface This is a case where the yellow of the intermediate layer 12 becomes stronger than the yellow of the layer 13. Accordingly, it becomes difficult to obtain a deep dark color tone, and the appearance of the front and back surfaces of the colored paper and the side appearance tend to deteriorate. In addition, due to the influence of the color tone of the intermediate layer 12 having a strong yellowish tint, the color tone that appears when the colored paper is viewed from the front surface 11 or the back surface of the back layer 13 may differ from the actual color tone. .

  On the other hand, if [b1-b2] exceeds 20, the hue difference between the hue (b1) of the front surface or the back surface and the hue (b2) of the intermediate layer 12 exceeds 20, and the surface layer 11 or the back layer 13 This is a case where the bluish color of the mid layer 12 becomes stronger than the bluish color of. Accordingly, it becomes difficult to obtain a deep dark color tone, and the appearance of the front and back surfaces of the colored paper and the side appearance tend to deteriorate. In addition, due to the influence of the color tone of the intermediate layer 12 having a strong yellowish tint, the color tone that appears when the colored paper is viewed from the front surface 11 or the back surface of the back layer 13 may differ from the actual color tone. .

The applied amount of the intermediate layer 12 is preferably 50 to 100 g / m ² .

When the weight of the intermediate layer 12 is less than 50 g / m ² , the basis weight of the colored paper is almost determined, so that the weight of the surface layer 11 and / or the back layer 13 is inevitably increased. Accordingly, the intermediate layer 12 is thin, and the surface layer 11 and / or the back layer 13 is thick. Therefore, the paper composed of a single layer, the surface layer 11, the intermediate layer 12, and the back layer 13 are colored in substantially the same color. Thus, the difference from the conventional colored paper is reduced, and it becomes difficult to obtain the effects peculiar to the present invention.

On the other hand, when the applied amount of the intermediate layer 12 exceeds 100 g / m ² , the thickness of the intermediate layer 12 is increased, and the thickness of the surface layer 11 and / or the back layer 13 is inevitably reduced. It is difficult to obtain the color tone. Therefore, the intermediate layer 12 also needs to be colored in the same dark color system as the surface layer 11 and the back layer 13. Therefore, it is necessary to use a very expensive colorant such as a dye, and there is a problem that the manufacturing cost is increased.

  In addition, this can be applied to the case of a colored paper having a lightness (L value) of 53 or less on the surface of the surface layer 11 and the back surface of the back layer 13, as in the case of the colored paper 10. In a light color system in which a certain color tone is not so required, it is possible to reduce the amount of the surface layer 11 and the back layer 13 as much as possible and increase the amount of the intermediate layer 12.

  As described above, the intermediate layer 12 of the colored paper 10 has the surface layer 11 so as to satisfy −40 ≦ L1-L2 ≦ −8, −15 ≦ a1-a2 ≦ 25, and −32 ≦ b1-b2 ≦ 20. And it is preferable to adjust by mixing white water generated in papermaking of the back layer 13 as dilution water of the raw material pulp of the intermediate layer 12.

  That is, as described above, the surface layer 11 and the back layer 13 adjust the hue (L1, a1, b1) by adding a colorant to the raw material pulp of each layer, and the intermediate layer 12 includes the surface layer 11 and the back layer 13. It is colored using the colorant in white water produced by papermaking. Thereby, since the coloring agent which colors the intermediate | middle layer 12 and adjusts a color tone is not required, manufacturing cost can be reduced and the appearance of this coloring paper 10 can be improved. Moreover, since the coloring agent in the white water of the surface layer 11 and the back layer 13 can be collect | recovered, the load of waste water treatment can also be reduced and manufacturing cost can be reduced further, and it is preferable.

  As the raw material pulp of the intermediate layer 12 of the colored paper 10, various known pulps can be used in the same manner as the raw material pulp of the surface layer 11 and the back layer 13. However, it is preferable to use waste paper pulp manufactured from old paper waste paper, corrugated paper waste paper, newspaper waste paper, especially when containing waste paper pulp derived from the old paper waste paper 50-100 mass%, preferably 60-100 mass% or more, This is preferable from the viewpoint of easily obtaining a desired color tone of the present invention, the manufacturing cost, and the like.

  The colored paper 10 is manufactured by laminating raw material pulps for the surface layer 11, the intermediate layer 12, and the back layer 13 in this order by a paper machine. That is, the colored paper 10 is formed by laminating the intermediate layer 12 on the surface of the surface layer 11 and laminating the back layer 13 on the surface of the intermediate layer 12, as shown in FIG. Depending on the model of the paper machine, the layers may be stacked in the reverse order.

  The colored paper 10 configured as described above is disclosed in J. Org. TAPPI No. The interlayer strength based on the 18-2 internal bond tester method is preferably 110 mJ or more, and more preferably 130 mJ or more. In addition, J.H. TAPPI No. The T-peeling strength based on the “maximum load measuring method” defined in 19-1 is preferably 180 g / 5 cm or more, and more preferably 280 g / 5 cm or more. As a result, even if the colored paper 10 is used for fancy paper such as a paper container or a book turnover and the fancy paper is subjected to a turning load, delamination hardly occurs.

  Various means can be used alone or in appropriate combination in order to improve the interlayer strength and the T-shaped peel strength and prevent the occurrence of delamination. That is, at the time of papermaking, the strength of the interlayer and the T-shape are added by means such as adding various paper strength enhancers, spraying adhesive between layers, adjusting dehydration at the wire part, selecting and blending raw material pulp, adjusting raw material freeness, etc. It is possible to improve the peel strength.

  Also, amphoteric polyacrylamide type paper strength enhancer, polyamide epichlorohydrin type paper strength enhancer, starches such as starch, oxidized starch, carboxymethylated starch, paper strength enhancer such as plant gum, polyvinyl alcohol, carboxymethylcellulose, etc. Is also an effective method, and the interlayer strength and T-peel strength of the colored paper 10 can be improved.

  In addition, when a paper strength enhancer is internally added to the raw material pulp, it contains a paper strength enhancer in the raw material pulp of each layer in order to ensure good surface / back surface appearance and side appearance as fancy paper. The amount is preferably 0.1 to 1.2% by mass in solid content.

  When the content of the paper strength enhancer is less than 0.1% by mass, the effect of improving the interlayer strength is small. On the other hand, even if the content exceeds 1.2% by mass, improvement in interlayer strength cannot be expected, and in addition, the texture of the colored paper deteriorates and it becomes difficult to ensure the appearance of the front and back surfaces as fancy paper. Furthermore, problems such as contamination of the paper machine equipment and increase of pollutants in the wastewater are likely to occur.

Moreover, the basic weight of this colored paper 10 is 70-150 g / m < ² >, Preferably it is 70-130 g / m < ² >, More preferably, it is 70-115 g / m < ² >.

If the basis weight of the colored paper 10 is less than 70 g / m ² , it is difficult to provide three layers of the surface layer 11, the intermediate layer 12, and the back layer 13, and the amount of attachment per layer is small, so that the low The amount of intermediate layer 12 that can be manufactured at a low cost is inevitably small. For this reason, a decrease in the manufacturing cost of the colored paper 10 is reduced.

On the other hand, when the basic weight of the colored paper 10 is larger than 150 g / m ² , the side appearance as fancy paper is deteriorated. In addition, it is possible to improve the side appearance as fancy paper by adding a large amount of dye to the intermediate layer 12 and coloring it. However, if a large amount of expensive dye is blended, the manufacturing cost increases.

  The paper making method of the colored paper 10 is not particularly limited, and any of an acidic paper making method, a neutral paper making method, and an alkaline paper making method may be used. In order to fix the colorant with a fixing agent and efficiently color the target dark color, the hot water extraction PH is set to 5 to 8.5. It is preferable to produce with acidic or neutral papermaking.

  Also, since the paper machine is not particularly limited, for example, various known paper machines such as a long net paper machine, a twin wire paper machine, a circular net paper machine, and a short net combination machine can be used. it can.

  As described above, the present colored paper 10 has been described with respect to the case where the paper layer is composed of the three layers of the surface layer 11, the intermediate layer 12, and the back layer 13. However, the present invention is not limited to such a colored paper 10. As shown in the figure, the number of layers of the intermediate layer 12 is increased to 5 layers, 6 layers, such as a colored paper 10 'composed of four paper layers of the surface layer 11, the intermediate layer 12, the intermediate layer 12', and the back layer 13. -Colored paper consisting of paper layers may be used.

  In order to confirm the effect of the multi-layered double-sided colored paper according to the present invention, the following various samples were prepared, and a test for evaluating the quality of each sample was performed. In addition, in a present Example, the numerical value which shows a mixing | blending, a density | concentration, etc. is a numerical value of the solid content or the mass reference | standard of an active ingredient. Moreover, since the pulp, chemical | medical agent, etc. which are shown in a present Example are only examples, it cannot be overemphasized that this invention is not restrict | limited by these Examples, and can be selected suitably.

  29 types of paperboards according to the present invention (referred to as “Example 1” to “Example 29”) and 6 types of paperboards (referred to as “Example 1” to “Example 29”) “Comparative Example 1” to “Comparative Example 6”) were prepared in the configurations shown in Tables 1 and 2. Moreover, two types of fancy papers were evaluated as reference examples.

［実施例１］
＜１＞表層及び裏層
広葉樹晒クラフトパルプ（ＬＢＫＰ）７５質量％と針葉樹晒クラフトパルプ（ＮＢＫＰ）２５質量％とを配合した後に、離解フリーネスを４００ｃｃに調整した表層用の原料パルプに、硫酸バンドを０．５質量％、サイズ剤（商品名：Ｒ−２２、近代化学株式会社製）を固形分換算で１．０質量％、乾燥紙力増強剤（商品名：ハーマイドＲＢ−３２、ハリマ化成株式会社製）を固形分換算で０．３質量％添加して表層用の原料スラリーを調整した。この表層用の原料スラリーに染料を添加し、表２に示すように、色相（Ｌ１，ａ１，ｂ１）を（３２．４，１５．８，４．５）に調整した。

[Example 1]
<1> Surface layer and back layer After blending 75% by mass of hardwood bleached kraft pulp (LBKP) and 25% by mass of softwood bleached kraft pulp (NBKP), a sulfuric acid band is added to the surface pulp for which the disaggregation freeness is adjusted to 400 cc. 0.5 mass%, sizing agent (trade name: R-22, manufactured by Modern Chemical Co., Ltd.) 1.0 mass% in terms of solid content, dry paper strength enhancer (trade name: Hermide RB-32, Harima Chemicals) Co., Ltd.) was added in an amount of 0.3% by mass in terms of solid content to prepare a raw material slurry for the surface layer. A dye was added to the raw material slurry for the surface layer, and as shown in Table 2, the hue (L1, a1, b1) was adjusted to (32.4, 15.8, 4.5).

The back layer used the same raw material slurry as the surface layer, and was adjusted to the same color tone as the surface layer.
<2> Intermediate layer After blending 70% by weight of the old paper pulp and 30% by weight of the upper white waste paper pulp, the raw material pulp for the intermediate layer adjusted to a disaggregation freeness of 400 cc is combined with 0.7% by weight and size of the sulfuric acid band. Agent (trade name: R-22, manufactured by Modern Chemical Co., Ltd.) in terms of solid content is 0.5% by mass, and dry paper strength enhancer (trade name: Hermide RB-32, manufactured by Harima Kasei Co., Ltd.) is converted into solid content. Was added at 0.3 mass% to prepare a raw material slurry for the intermediate layer.

  Into the raw material slurry for the intermediate layer, white water produced in the surface layer and back layer papermaking is mixed, and a slight amount of dye is added as necessary, and as shown in Table 2, the hue (L2, a2 , B2) was adjusted to (57.4, 9.8, 3.0).

Using these raw material slurries, the surface layer, the intermediate layer, and the back layer paper layer are made with a circular three-layer paper machine, the surface layer weight is 26 g / m ² , and the intermediate layer weight is 68 g / m ² . A multilayer double-sided double-sided colored paper (Example 1) having a basis weight of m ² , a back layer application amount of 26 g / m ² , and a basis weight of the entire multilayer double-sided colored paper of 120 g / m ² was obtained. .
[Examples 2 to 5]
Multilayered double-sided colored paper obtained in the same manner as in Example 1 except that the lightness (L1) of the front and back layers and the lightness (L2) of the intermediate layer were adjusted to the values shown in Table 2.
[Examples 6 to 8]
A multilayer double-sided colored paper obtained in the same manner as in Example 1 except that the lightness (L2) of the intermediate layer was adjusted to the values shown in Table 2.
[Examples 9 to 13]
Multilayered double-sided colored paper obtained in the same manner as in Example 1 except that the hue (a1) of the front and back layers and the hue (a2) of the intermediate layer were adjusted to the values shown in Table 2.
[Examples 14 to 19]
The raw material pulp for the intermediate layer is 100% by mass of the old paper pulp, and the amount of the internal paper strength enhancer added to the surface layer, the intermediate layer, and the back layer is as shown in Table 1, and the hue of the intermediate layer Other than that (a value) was adjusted to the values shown in Table 2, the multi-layered double-sided colored paper obtained in the same manner as in Example 1.
[Examples 20 to 25]
The raw material composition of the raw material pulp of the surface layer and the back layer, and the raw material composition of the raw material pulp of the intermediate layer were blended as shown in Table 1, and the hue (b1) of the intermediate layer was adjusted to the values shown in Table 2. Except for the points other than the above, multilayer double-sided colored paper obtained in the same manner as in Example 1.
[Examples 26 to 29]
Multi-layered double-sided paper obtained in the same manner as in Example 1 except that the raw material composition of the raw material pulp of the intermediate layer was blended as shown in Table 1 and the basis weight was adjusted to the values shown in Table 1. Colored paper.
[Comparative Example 1]
Multilayered double-sided colored paper obtained in the same manner as in Example 1 except that the lightness (L1) of the front and back layers and the lightness (L2) of the intermediate layer were adjusted to the values shown in Table 2.
[Comparative Example 2]
A multilayer double-sided colored paper obtained in the same manner as in Example 1 except that the lightness (L1) of the intermediate layer was adjusted to the values shown in Table 2.
[Comparative Examples 3 and 4]
Multilayered double-sided colored paper obtained in the same manner as in Example 1 except that the hue (a1) of the surface layer and the back layer and the hue (a2) of the intermediate layer were adjusted to the values shown in Table 2.
[Comparative Examples 5 and 6]
A multilayer double-sided colored paper obtained in the same manner as in Example 1 except that the basis weight was adjusted to the values shown in Table 1.
[Reference Example 1]
A commercially available fancy paper 120 g / m ² (single-layer paper product) was evaluated in the same manner as in the examples.
[Reference Example 2]
Commercially available fancy paper 120 g / m ² (multilayer paper product / intermediate layer is adjusted to the same color tone as the front and back layers) was evaluated in the same manner as in the examples.

Here, “basis weight (g / m ² )” in Table 1 is a value measured according to “paper and paperboard—basis weight measuring method” described in JIS-P8124.

“Amount (g / m ² )” is a value obtained by delaminating each of the above samples, and measuring the rice tsubo of each layer in accordance with “Paper and paperboard—basis weight measurement method” described in JIS-P8124. It is.

  The delamination is performed according to the following procedure. First, each sample obtained from each sample is immersed in water at room temperature for about 1 hour. Each sample immersed in water is wound around a round bar of about 10 mmΦ starting from a corner, and then the round bar is rolled to squeeze each sample. This operation is repeated starting from all four corners of each sample, and the ironing force is applied to the sample from each direction. As a result, a part of the layers of each sample is peeled off, and this is used to separate the layers into a surface layer, an intermediate layer, and a back layer. After delamination, each layer of each sample was sufficiently dried with a hot air dryer or the like and used for the test.

  “Hue (L, a, b)” in Table 2 is a value of Hunter Lab (C light source) measured with a color difference meter in accordance with JIS-Z-8722 “Measurement method of object color”. .

  Quality evaluations for all of these Examples, Comparative Examples, and Reference Examples, that is, the results of evaluation tests on appearance, interlaminar strength (internal bond and T-peel strength), operability, and manufacturing cost are as follows. As shown in FIG.

  In addition, “appearance” in Table 3 is a visual evaluation of the appearance from the front, back, and cross section of each sample, and the evaluation criteria are: "There is a solid feeling (uniformity, calmness), and there is no color effect on the intermediate layer.", "Oh," The texture is clear and the solid feeling is slightly inferior, but there is no color effect on the intermediate layer. " The three stages of “X” are “Poor feeling, no solid feeling, and there is an influence of the color of the intermediate layer”. In addition, the appearance of the cross section is marked with “◎”, “There is no sense of incongruity in the color of the cross section even when looking at the side with 10 sheets of paper.”, “With 10 sheets of paper, the color tone is somewhat uncomfortable. If there is one sheet, there is no sense of incongruity in the cross-section color tone, and “x” indicates that “the cross-section color tone has a sense of incongruity.

  “Internal Bond (mJ)” means JAPAN TAPPI No. It is a value measured by the internal bond tester method specified in 18-2.

  “T-shaped peel strength (g / 5 cm)” means JAPAN TAPPI paper pulp test method no. 19-1 A value of T-peel strength between the surface layer and the intermediate layer measured by the maximum load measurement method.

  "Operability" is an evaluation of the operability during paper making when comparing existing multi-layered colored paper with the middle layer adjusted to the same color as the front and back layers. “Comparing to existing multi-layered colored paper, it is very easy to adjust the color tone and easy to manufacture stably.” ”And“ x ”,“ the color tone adjustment is more complicated than existing multi-layered colored paper ”.

In addition, “production cost” is an evaluation of whether or not it can be produced at low cost when compared with an existing multi-layered colored paper in which the intermediate layer is adjusted to the same color tone as the front and back layers. ◎ “Manufactured at a very low cost compared to existing multi-layered colored paper, which is a great advantage.” ○ ○ “Compared to existing multi-layered colored paper, it can be manufactured at a low cost. The method can be adopted, ”and“ x ”,“ compared with existing multi-layer colored paper, has no cost merit and is not worth adopting the method. ”

表３に示すように、本発明に係る多層抄き両面着色紙、すなわち実施例１〜２９に係る着色紙であると品質評価に優れることが分かる。すなわち、着色紙をファンシーペーパーとして用いられた際の見映えに優れ、層間強度に優れ、さらに、操業性、及び製造コストが良好な多層抄き両面着色紙を得ることができる。

As shown in Table 3, it can be seen that the multilayer paper double-sided colored paper according to the present invention, that is, the colored paper according to Examples 1 to 29, is excellent in quality evaluation. That is, it is possible to obtain a multilayer double-sided colored paper that is excellent in appearance when colored paper is used as fancy paper, has excellent interlayer strength, and has good operability and manufacturing cost.

It is a schematic sectional drawing of the multilayer papermaking double-sided colored paper which concerns on this invention. It is a schematic sectional drawing of the other multilayer papermaking double-sided colored paper which concerns on this invention.

Explanation of symbols

10, 10 'Colored paper 11 Surface layer 12, 12' Intermediate layer 13 Back layer

Claims (5)

A multilayer double-sided colored paper having a basis weight of 70 to 150 g / m ² having at least a surface layer, a back layer, and an intermediate layer composed of one or more layers disposed between the surface layer and the back layer. ,
The color tone of the surface layer and the back layer is obtained by adding a colorant to the raw material pulp of the surface layer and the back layer.
The brightness (L value) of the surface of the surface layer and the back surface of the back layer is 53 or less,
The hue (a value) of the surface of the surface layer and the back surface of the back layer is in the range of −33 to 33, and the color tone of the surface of the surface layer and the color tone of the back surface of the back layer are adjusted to be approximately the same. And
The lightness (L value) of the intermediate layer is adjusted to −40 ≦ L1−L2 ≦ −8, where L1 is the lightness of the front surface and the back surface of the back layer, and L2 is the lightness of the intermediate layer. Multi-layered double-sided colored paper characterized by Multilayer paper making sided colored paper according to claim 1, each with the amount of said surface layer and said backing layer is characterized by a 25 to 50 g / m ^2. The hue of the front surface and the back surface is (a1, b1) and the hue of the intermediate layer is (a2, b2), and −15 ≦ a1-a2 ≦ 25 and −32 ≦ b1-b2 ≦ 20. The multi-layered double-sided colored paper according to claim 1 or 2. At least each raw material pulp of the surface layer and the back layer contains 10-50% by mass of softwood pulp, and at least the surface layer and the back layer contain a paper strength enhancer in a solid content with respect to each raw material pulp. The multilayer double-sided colored paper according to any one of claims 1 to 3, which is contained in an amount of 0.1 to 1.2% by mass. 5. The raw material pulp of the intermediate layer is colored by mixing white water produced by papermaking of the surface layer and the back layer into the white water of the intermediate layer. The multilayer double-sided colored paper described.

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