JP5133587B2 - Paper or paperboard for packaging containers with cushion function - Google Patents

Description

  The present invention relates to a paper or paperboard having an excellent cushioning property and having a cushioning function capable of preventing a packaged article from entering into a mold or being damaged.

  Conventionally, for example, interior doors used for houses, interior fittings such as indoor doors, housing, building materials for housing such as stairs and stairs members, flooring, flooring, etc., and plastic materials such as air conditioners, TVs, DVD recorders, etc. When goods used (hereinafter referred to as “packages”) are transported or stored, they are often packed in a packaging container such as a cardboard case.

  However, if a packaged item is directly packed in a corrugated cardboard case, the commercial value of the packaged item may be reduced. In other words, if the package is packed directly in a cardboard case without being wrapped with a protective material such as non-woven fabric, the corrugated cardboard case (corrugated cardboard sheet) will enter the package as a mold, or the surface of the package In some cases, the product value of the packaged goods may be reduced.

  Therefore, in order to prevent the cardboard case from entering the package as a mold or to prevent the surface of the package from being finely scratched, the package is packaged with a protective material such as a nonwoven fabric. It is performed to pack in a cardboard case or to put a cushion material such as a bubble cushion material in the cardboard case.

  However, when the protective material and the cushion material are added in this way, there is a problem that not only the cost for packaging is increased, but also the labor for packaging is required.

  Thus, for example, a packaging member as described in Patent Document 1 has been proposed. That is, two rectangular resin films are overlapped, an air blowing member having a check valve structure is interposed, and the outer peripheral edge portion is heat sealed, and a plurality of partition heat seal portions are formed. A packaging member in which adjacent air chambers are formed, in which a paper sheet material is integrally attached to one side of a resin film, and a surface on which the paper sheet material is attached is outside and each air chamber is an object to be packaged. A packaging member has been proposed which is configured to be used as a packaging container having a cushion function by packaging the whole so as to contact the surroundings, and sticking and fixing the free end of the packaging member with an adhesive tape in the packaged state. ing.

  Although such a packaging member can solve the problem of taking time and effort for packaging, since two members of the packaging material, the protective material and the cushion material are necessary, the protective material and the cushion material The problem of higher costs was not solved.

JP 2006-69621 A

  The present invention has been made in view of the above-described circumstances, and its object is to provide a protective material and a cushion material for preventing a packaged article, such as a nonwoven fabric or a bubble cushion material, from entering a mold or being damaged. A paper or paperboard that has a cushioning function that is excellent in cushioning properties and can prevent a packaged object from being scratched or molded, and a packaging container and a cushion material formed using the paper or paperboard. There is to do.

The above object of the present invention is to provide a base paper and a coating layer provided by applying a coating liquid containing at least a thermally foamable particle and a binder having a glass transition temperature of 30 to 70 ° C. on at least one side of the base paper. at least comprising the door, the heat expandable particles, said the coating layer are contained 5-20 wt% in terms of solid content, the coating layer, the thermal expandable particles and a binder, and dried This is achieved by providing a paper or paperboard for packaging containers having a cushion function, wherein the thermally foamable particles are foamed to form a cushion layer.

Moreover, the said objective of this invention contains the said thermally foamed particle and the said binder in the ratio of 7-50: 93-50 by solid content ratio, and the coating amount of the said coating liquid is solid content conversion per single side | surface. In the drying step of 16 to 120 g / m ² and a drying temperature of 100 to 120 ° C., the coating layer is used as a cushion layer, and the basis weight including the coating layer is in the range of 180 to 500 g / m ² . It is effectively achieved by providing a paper or paperboard for a packaging container having a cushion function characterized by being.

The above-described object of the present invention, cushioning of the paper or paperboard, the coefficient of restitution used as an index of evaluation of the cushioning, wherein the coefficient of restitution, characterized in that a 0.40 to 0.50 cushion It is more effectively achieved by providing a paper or paperboard for packaging containers with functionality.

Furthermore, the above object of the present invention, the by using the packaging container or cushion material of paper or paperboard of packaging applications comprising a cushioning function of any one, is more effectively achieved.

  According to the paper or paperboard having a cushion function according to the present invention, a base paper and a coating layer provided by applying a coating liquid containing at least a thermally foamable particle and a binder to at least one surface of the base paper. At least, the thermally foamable particles are foamed by drying the coating layer to form a cushion layer. Therefore, the cushioning layer has excellent cushioning properties and can prevent the packaged object from being scratched or molded. Therefore, it is not necessary to use a protective material or a cushion material for preventing the packaged item from being damaged or mold-molded, and the process can be simplified and the cost can be reduced.

  Further, since the thermal expandable particles containing 5 to 20 wt% in terms of solid content in the coating layer, it is possible to obtain a cushioning property, and also good adhesion between the base paper and the coating layer, heat There is no separation of the expandable particles.

Furthermore, since the coating amount of the coating liquid is set to 16 to 120 g / m ^{2 in} terms of solid content per side, the cushioning property, the scratch preventing property and the mold preventing property can be further improved.

  Hereinafter, the paper or paperboard provided with the cushion function according to the present invention will be described in detail. Incidentally, paper or paperboard according to the present invention is not limited to the following embodiments in a range not departing from the scope of the appended claims, can of course be appropriately changed its configuration.

  Paper or paperboard having a cushion function according to the present invention (hereinafter referred to as “main paper or paperboard”) is applied by applying a coating liquid containing at least thermally foamable particles and a binder to at least one surface of a base paper. After that, the coating layer is dried to foam the thermally foamable particles to form a cushion layer.

  Thereby, this paper or paperboard comes to have an excellent cushioning property. In other words, the main purpose of this paper or paperboard is to process it into a packaging container such as a cardboard case, a cushioning material or the like. Therefore, since packaging containers and cushion materials formed using genuine paper or paperboard have excellent cushioning properties, it is possible to prevent the surface of the package from being damaged without using protective materials or cushion materials. (Hereinafter referred to as “prevention of scratches”), and a step such as a corrugated cardboard sheet can be prevented from entering the surface of the packaged object as a mold (hereinafter referred to as “prevention of mold”).

  The “paper or paperboard having a cushion function” described in the present specification means a cushion function that is not found in general printing paper, cardboard base paper, paperboard, etc. This refers to paper or paperboard that has a function to soften the collision or impact that occurs between the package and the paper or the paperboard and the packaged product.

  The base paper used for the main paper or the paperboard is not particularly limited. For example, the base paper can be appropriately selected from various materials such as fine paper, art paper, coated paper, glossy paper, impregnated paper, and paperboard depending on the intended use. You can select and use.

  However, when this paper or paperboard is processed into a packaging container such as a cardboard case used for transporting, storing and protecting the packaged goods, and used as a packaging material, or when processed into a cushioning material, It is preferable to use paperboard such as corrugated cardboard or cardboard as the base paper.

  Further, the main paper or paperboard is provided with a coating layer (cushion layer) by applying a coating liquid on at least one side of the base paper. For this reason, it is preferable that the Beck smoothness of the surface of the base paper to which the coating liquid is applied is 45 seconds or less, preferably 30 seconds or less, more preferably 20 seconds or less. That is, when the Beck smoothness of the base paper exceeds 45 seconds, the adhesiveness between the coating layer and the base paper tends to decrease. For this reason, when the heat-foamable particles contained in the coating layer are foamed into a cushion layer by heating when the coating layer is dried, there is a problem that the cushion layer is lifted off from the base paper and peeled off. Prone to occur.

  As described above, the coating liquid applied to at least one side of the base paper contains at least thermally foamable particles and a binder. That is, if the coating solution contains thermally foamable particles, the coating layer is dried and heated to expand and foam the thermally foamable particles, and the coating layer is used as a cushion layer. Sex can be obtained. Moreover, the surface intensity | strength of this paper or paperboard can be improved by containing a binder. Therefore, when this paper or paperboard is processed into a packaging container such as a cardboard case, cushioning material, etc. and used for transporting or storing the packaged items, the paper may be peeled or torn due to rubbing during transportation or storage. Can be prevented. Thereby, since this paper or paperboard becomes excellent in cushioning property, damage prevention property, and mold prevention property, it is possible to prevent damage to the packaged item and entering the die.

  Below, the heat-expandable particle | grains and binder which are contained in the coating liquid used for this paper or paperboard are explained in full detail.

  The thermally foamable particles are contained in the coating layer in an amount of 5 to 20% by mass, preferably 7 to 17% by mass in terms of solid content. When the content of the heat-expandable particles is less than 5% by mass, even if the heat-expandable particles are in a foamed state, the density of the heat-expandable particles is low. It becomes difficult to obtain. On the other hand, when the content of the thermally foamable particles exceeds 20% by mass, the cushioning property is excellent, but the adhesiveness between the base paper and the coating layer is lowered. Further, the heat-expandable particles are likely to be detached, and problems such as adhesion of the detached heat-expandable particles to the package are likely to occur.

  Incidentally, when it is desired to increase the content of the thermal expandable particles contained in the newspaper or paperboard, the content of the thermal expandable particles per coated layer one layer remains 5-20 wt%, the coating It is preferable to provide two or more layers. This makes it easier to obtain cushioning properties of the main paper or paperboard.

  As the thermally foamable particles, particles obtained by encapsulating a low boiling point solvent in a fine particle outer shell made of a thermoplastic synthetic resin can be used. These heat-expandable particles have an average particle size of 5 to 30 μm, and expand at a diameter of 4 to 5 times and a volume of 50 to 130 times when heated at 90 to 200 ° C.

  Examples of the thermoplastic synthetic resin constituting the outer shell include copolymers such as vinylidene chloride, acrylonitrile, acrylic acid ester, and methacrylic acid ester. As the low-boiling solvent which is encapsulated within an outer shell, for example, it may be mentioned isobutane, pentane, petroleum ether, hexane, low boiling halogenated hydrocarbons, methylsilane, and the like.

  Examples of such thermally expandable particles include “Matsumoto Microsphere F-20 Series”, “F-30 Series”, “F-36 Series”, and “F-46” manufactured by Matsumoto Yushi Seiyaku Co., Ltd. Series "and, Japan Fillite Co., Ltd. of sales" Expancel WU "," what is Aix it is possible to use the bread cell DU "and the like, heat expandable particles to be used in the actual paper or paperboard, which is limited to is not.

  The thermally foamable particles are heated above the softening point of the thermoplastic synthetic resin that constitutes the outer shell, and at the same time, the encapsulated low boiling point solvent evaporates and the vapor pressure rises. Inflate. During expansion, the internal pressure and the shell tension / external pressure are balanced to maintain the expanded state. The thermally foamable particles are generally expanded to this state and used as a lightening agent, a bulking agent, a heat insulating agent or the like. When further heat is applied to the thermally expanded particles in the expanded state, gas permeates and diffuses from the expanded and thin shell, and the shell tension / external pressure becomes larger than the internal pressure, resulting in expanded particles. Will shrink.

  The thermally foamable particles used for the paper or paperboard are foamed by a dryer in the drying process. Therefore, since the temperature of the paper drying step is generally about 120 ° C., it is preferable to use low-temperature expansion type thermally expandable particles having an expansion start temperature of 90 to 130 ° C. In particular, when the expansion start temperature is a heat-expandable particle having a temperature of less than 90 ° C., when expanded by a dryer in the drying process, the expanded particle once again contracts as described above, thereby obtaining a predetermined cushioning property. It becomes difficult.

  On the other hand, when the expansion start temperature exceeds 130 ° C., there arises a problem that the heating temperature in the drying / foaming process and foaming failure due to insufficient heat quantity are generated. In addition, in order to obtain an appropriate heating temperature and amount of heat, it is necessary to significantly reduce the manufacturing speed, resulting in a reduction in production efficiency.

  As described above, one purpose of the main paper or paperboard is to be processed into a packaging container or a cushion material. When the paper or paperboard is processed into a packaging container or cushion material, a strong bending force is applied to the ruled line portion (folded portion). Accordingly, it is required that the coating layer of the main paper or paperboard does not break the coating layer (cushion layer) even when such a strong force is applied, and that the coating layer does not lift up and peel off from the base paper. . For this reason, it is preferable to contain 20-65 mass% of binder in conversion of solid content in a coating layer.

  When the binder content is less than 20% by mass, the adhesiveness with the thermally foamable particles becomes insufficient, the thermal foamable particles are easily detached, and the adhesiveness with the base paper may be insufficient. On the other hand, if the binder content exceeds 65% by mass, the adhesiveness of the heat-expandable particles is hardly improved, and conversely, the coating failure due to thickening or the foaming of the heat-expandable particles is hindered, resulting in a foam failure. It becomes easy. That is, when the expansion and foaming of the heat expandable particles is hindered, it is impossible to impart cushioning properties to the actual paper or paperboard, decreases also result scratch-containing anti--type containing anti properties.

  Examples of such binders include water-dispersed binders such as styrene-butadiene latex, acrylic emulsion, acrylic-styrene emulsion, vinyl acetate emulsion, and urethane emulsion; starch, modified starch, polyvinyl alcohol (PVA), and the like. A water-soluble binder etc. can be used individually or in combination of 2 or more types.

  However, since the coating liquid used for the paper or paperboard also contains thermally foamable particles as described above, depending on the type and properties of the binder, the adhesiveness to the thermally foamable particles and the adhesion to the base paper May cause problems in terms of heat resistance, foaming suppression of heat-foamable particles, heat resistance in drying / foaming processes due to heating, and may cause problems such as a decrease in surface strength of paper or paperboard and quality troubles.

  For this reason, it is preferable to use a styrene-butadiene latex, an acrylic emulsion, or a urethane emulsion among the binders described above, and it is particularly preferable to use an acrylic emulsion. That is, styrene-butadiene latex, acrylic emulsion, and urethane emulsion have adhesiveness with thermally foamable particles and adhesiveness between the coating layer formed by applying this coating liquid and the base paper. It is good and does not hinder the expansion / foaming of the thermally foamable particles, and can prevent the packaged object from being damaged.

  Furthermore, when the glass transition temperature (Tg) of the binder is 30 to 70 ° C., preferably 40 to 60 ° C., expansion and foaming of the thermally foamable particles are not hindered, and foaming can be performed satisfactorily. Moreover, it is excellent in the adhesiveness with a thermally foamable particle and the adhesiveness of a coating layer and a base paper. Furthermore, the surface strength of the paper or paperboard can be improved after the coating layer is dried.

  When the glass transition temperature (Tg) of the binder is less than 30 ° C., a problem that the binder is easily taken on the hot plate of the corrugator at the time of bonding to the corrugated cardboard sheet is likely to occur. On the other hand, if the glass transition temperature (Tg) of the binder exceeds 70 ° C., although it is excellent in the effect of improving the surface strength of paper or paperboard, it inhibits the expansion / foaming of the thermally foamable particles. It is not possible to obtain cushioning properties.

  In addition, as described above, the coating layer of the main paper or paperboard does not break the coating layer (cushion layer) even if such a strong force is applied, and the coating layer does not lift and peel off from the base paper. Is required. For this reason, it is preferable that a thermally foamable particle and a binder are contained in a coating layer in the ratio of 7-50: 93-50 by solid content ratio.

  If the ratio of the heat-expandable particles is less than 7% by mass, the desired cushioning property of the present application cannot be obtained even if the heat-expandable particles are sufficiently expanded. On the other hand, when the ratio of the heat-expandable particles exceeds 50% by mass, the adhesiveness between the heat-expandable particles and the binder is lowered, and the heat-expandable particles may be detached.

  As described above, the coating liquid applied to at least one side of the base paper or the paperboard base sheet contains at least a thermally foamable particle and a binder as described above. Various known materials such as a foaming agent, a dispersing agent, and a viscosity adjusting agent may be contained.

  The coating liquid used for the main paper or paperboard constituted as described above contains 40 to 70% by mass, preferably 45 to 65% by mass of the coating composition (solid content).

As described above, the coating liquid containing at least thermally foamable particles and a binder is 16 to 120 g / m ² , preferably 40 to 100 g / m ² , more preferably 52 to 52 per side of the base paper in terms of solid content. 100 g / m ^{2 is} applied. When the coating amount of the coating liquid is less than 16 g / m ² , cushioning properties and scratch resistance are low. On the other hand, when the coating amount exceeds 120 g / m ² , the cushioning property and the effect of preventing damage to the packaged article are excellent, but the adhesion between the base paper and the cushion layer is poor, the productivity is greatly reduced, and the cost is increased. Will be invited.

  In addition, as a method for applying the coating liquid to at least one surface of the base paper, known coating means such as a bar coater, a rod coater, an air knife or the like can be used. Moreover, it can print by well-known printing means, such as a gravure printing machine and a flexographic printing machine, and can also provide a coating layer in the at least single side | surface of a base paper.

  However, compared to typical coating amount of the coated paper for printing, coating amount of the coating fluid is applied to at least one surface of the base paper of newspaper or paperboard are numerous, it is applied in a paper machine difficult. For this reason, in this invention, it is preferable to apply multilayer coating with a printing machine. The printing press may be a multilayer coating using a plurality of printing units, especially flexo printing machine with printing units having 4 to 12 units, it is effective to apply the coating liquid to the surface of the base paper It is.

  When applying the coating liquid with a flexographic printing machine, the Zahn cup no. The viscosity of the coating solution is adjusted so that the value measured at 4 (25 ° C.) is 8 to 30 seconds, preferably 15 to 20 seconds. When the viscosity of the coating liquid is less than 8 seconds, it becomes difficult to hold the coating liquid with an anilox roll, and uneven coating occurs, or the desired coating amount of the present application cannot be applied. Problems are likely to occur. On the other hand, when the viscosity of the coating solution exceeds 30 seconds, it is difficult to uniformly supply the coating solution to the anilox roll, and coating unevenness is likely to occur.

The basis weight including the coated layer of the paper or paperboard formed as described above is the content of the packaged item, the packaging container such as the cardboard case in which the paper or paperboard is processed, the size, shape, and weight of the cushioning material. Although also vary according to the use of such is, is preferably in the range of 180~500g / ^{m 2,} more preferably in the range of 180~400g / ^{m 2.} When the basis weight of the paper or paperboard is less than 180 g / m ² , when the paper or paperboard is processed into a packaging container or cushion material such as a cardboard case, the strength and rigidity as the packaging container and cushion material are inferior. Further, even if a coating layer is provided on at least one side of the base paper and the cushion layer is formed, the base paper is thin, so that it is difficult to obtain the desired cushioning property, damage prevention effect, and step prevention effect. On the other hand, even if the basis weight of the main paper or paperboard is larger than 500 g / m ² , the quality is excessive and the manufacturing cost is only increased.

In addition, when paper or paperboard is processed into a packaging container or cushion material used when packaging small products that are easily damaged by the surface of glass products, plastic products, etc., kraft as the base paper It is preferable to use paper or thin paper. In addition, in the case of such a use, it is preferable that the basic weight of this paper or paperboard containing a coating layer is 100 g / m < ² > or less. Even if a coating layer is provided on at least one side of the base paper having such a basis weight and the cushion layer is formed, the desired cushioning property, scratch prevention effect and step prevention effect can be obtained.

  After applying the coating liquid to the surface of the base paper to form a coating layer, the coating layer is heated and dried in a drying process, and at the same time, the foamed thermally foamable particles in the coating layer are foamed to form the coating layer as a cushion layer. To do.

  The drying temperature in the drying step is preferably 100 to 120 ° C. When the hot air is 100 to 120 ° C., the moisture in the coating layer is evaporated and dried, and in this drying step, the coating layer can be used as a cushion layer. When the drying temperature is less than 100 ° C., foaming of the heat-expandable particles in the coating layer is insufficient, and it becomes difficult to obtain a desired cushioning property. On the other hand, when the drying temperature exceeds 120 ° C., although depending on the drying time, the heat-expandable particles may exceed the maximum expansion rate due to overheating and may shrink.

  Furthermore, the main paper or paperboard is obtained by heating the heat-expandable particles contained in the coating layer when the coating liquid is dried (primary heating), for example, when bonding the main paper or paperboard to a corrugated cardboard sheet. The foaming is preferably performed by two-stage heating of the corrugator using a hot plate (secondary heating). That is, in the drying step of the coating layer (coating liquid), the heat-expandable particles are expanded to a maximum expansion rate or less, and then the heat of the corrugator hot plate when the main paper or paperboard is bonded to a corrugated cardboard sheet, for example. Utilizing it, it is preferable to completely foam the thermally foamable particles after bonding the corrugated cardboard sheet. This is because if the heat-expandable particles are completely foamed during coating and drying, the heat-expandable particles may exceed the maximum expansion coefficient due to the heat of the hot plate of the subsequent corrugator and conversely shrink.

  In addition, since the main paper or paperboard is taken up after coating and drying, the paper core of the take-up, that is, the part at the beginning of winding, is subjected to a considerably larger pressure than the part at the end of winding. Therefore, at the time of winding the paper tube, the cushion layer obtained with great pressure is crushed by the pressure, and the cushioning property may be lowered.

  The paper or board obtained as described above is bonded with a corrugator to obtain a corrugated cardboard sheet.

  The temperature of the corrugator hot plate is preferably 150 to 180 ° C., and the temperature of the paper surface is preferably adjusted to 80 to 130 ° C. Thereby, shrinkage | contraction of the heat-expandable particle | grain by the amount of overheating can be prevented, a heat-expandable particle can be expanded appropriately, and desired cushioning properties can be obtained.

  The paper or paperboard obtained as described above has a cushioning property of 0.40 to 0.50, preferably 0.41 to 0.45, measured by the following measuring method.

The measuring method of cushioning properties is as follows.
(1) As a collision object, use a flat and sturdy test stand with a flat surface, and fix the cushion layer of the test sample so that it becomes the surface.
(2) Using an iron ball (pachinko ball) as a collision object on the surface of the test sample, it is dropped vertically from the height of 30 cm to the test sample.
(3) The rebound when the iron ball dropped was video-recorded, and the height of the rebound was measured in mm with a ruler set in the direction of fall.
(4) The coefficient of restitution was calculated according to the following (Equation 1) using the measured values of the drop height and the bounce height of the iron ball.
(Formula 1)
e = √ (h / ho) (e: coefficient of restitution, ho: height of fall, h: height of bounce)
(0 ≦ e ≦ 1)
(5) That is, this restitution coefficient was used as an index of cushioning properties, and it was determined that the cushioning properties were higher as the restitution coefficient was larger.

  Since the cushion property measured by such a measuring method is 0.40 to 0.50, the present paper or paperboard has an excellent cushion property, an anti-mold effect, and an anti-scratch effect. Therefore, if this paper or paperboard is processed into a packaging container such as a cardboard case or a cushioning material, it can be put into the package without using a protective material or cushioning material such as a nonwoven fabric or a bubble cushioning material. Can be prevented, and scratches can be prevented.

  In order to confirm the effect of the paper or paperboard having the cushion function according to the present invention, the following various samples were prepared, and a test for evaluating the quality of each of these samples 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 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.

  To compare with the paper or paperboard comprising 24 different cushioning function according to the present invention (to no "Example 1" This is referred to as "Example 24"), and these Examples 1 through 24, 2 Various types of paper or paperboard (referred to as “Comparative Example 1” and “Comparative Example 2”) were prepared as shown in Table 1. Moreover, as a reference example, a commercially available paperboard (referred to as “Comparative Example 3”) and a commercially available nonwoven fabric (referred to as “Comparative Example 4”) were evaluated.

（実施例１）
＜基紙＞
基紙として、坪量が２２０ｇ／ｍ^２である市販の段ボール用原紙（大王製紙株式会社製の商品名「ジャストＫライナー」）を用いた。なお、この段ボール用原紙の表面のベック平滑度は１８秒であった。
＜塗工液の調整＞
熱発泡性粒子として、マツモト油脂製薬株式会社製の「マツモトマイクロスフェアＦ−４６」を塗工層に対して固形分換算で１０質量％、またバインダとして、御国色素株式会社製のアクリル系エマルション「バインダＣＦ」を塗工層に対して固形分換算で４５質量％含有するように塗工液を作成し、調整した。なお、調整後の塗工液のザーンカップＮｏ．４（２５℃）で測定した粘度は１８秒であった。また、表１中の塗工液のバインダの種類の欄の「ア」とは、アクリル系エマルションを示す。

Example 1
<Base paper>
As the base paper, a commercially available cardboard base paper having a basis weight of 220 g / m ² (trade name “Just K Liner” manufactured by Daio Paper Co., Ltd.) was used. The Beck smoothness of the surface of the cardboard base paper was 18 seconds.
<Adjustment of coating solution>
As a thermally foamable particle, “Matsumoto Microsphere F-46” manufactured by Matsumoto Yushi Seiyaku Co., Ltd. is 10% by mass in terms of solid content with respect to the coating layer. A coating solution was prepared and adjusted so as to contain “binder CF” in an amount of 45 mass% in terms of solid content with respect to the coating layer. The adjusted coating solution Zahn cup No. The viscosity measured at 4 (25 ° C.) was 18 seconds. In Table 1, “A” in the column of the binder type of the coating liquid indicates an acrylic emulsion.

<Manufacture of paperboard with cushion function>
A coating layer is formed on the surface (one side) of a baseboard corrugated cardboard using a flexographic printing machine to form a coating layer by converting to 55 g / m ^{2 in} terms of solid content, and then a hot air dryer at 110 ° C. 15 The thermally foamable particles were primarily heated for 2 seconds to expand (foam), and the coating layer was used as a cushion layer to obtain a paperboard (Example 1) having a basis weight of 275 g / m ² .

  Furthermore, after obtaining Example 1, the bonding process to a corrugated cardboard sheet was assumed, and it put into a 150 degreeC hot air dryer for 10 second, and performed the secondary heating, and the thermally foamable particle was completely foamed. At this time, the temperature of the cushion layer was 125 ° C.

(Examples 2 to 6)
It was obtained in the same manner as in Example 1 except that the content of the heat-foamable particles, the solid content ratio between the heat-foamable particles and the binder, and the solid content in the coating liquid were changed as shown in Table 1. Paperboard with a cushion function.

(Examples 7 to 9)
Example 1 except that the content of the heat-expandable particles, the content of the binder, the solid content ratio of the heat-expandable particles and the binder, and the solid content in the coating liquid were changed as shown in Table 1. A paperboard having a cushion function obtained in the same manner.

(Examples 10 to 16)
Other than changing the content of the heat-foamable particles, the solid content ratio between the heat-foamable particles and the binder, the solid content in the coating liquid, the coating amount of the coating liquid, and the basis weight as shown in Table 1. Is a paperboard having a cushion function obtained in the same manner as in Example 1.

(Example 17)
Example 1 except that the content of the heat-expandable particles, the type of binder, the solid content ratio between the heat-expandable particles and the binder, and the solid content in the coating liquid were changed as shown in Table 1. Paperboard with a cushion function. In the table, “SBR” in the column of the binder type represents styrene-butadiene latex, and “Nipol LX” manufactured by Nippon Zeon Co., Ltd. was used as SBR in this example.

(Examples 18 to 23)
Example 1 except that the content of the thermally foamable particles, the glass transition temperature of the binder, the solid content ratio between the thermally foamable particles and the binder, and the solid content in the coating liquid were changed as shown in Table 1. A paperboard with a cushion function obtained in the same manner as above.

(Example 24)
The content of the heat-expandable particles, the solid content ratio between the heat-expandable particles and the binder, and the solid content in the coating liquid are changed as shown in Table 1, and the heat-expandable particles are expanded only by primary foaming. A paperboard having a cushion function obtained in the same manner as in Example 1 except that foaming was performed.

(Comparative Example 1)
The content of the heat-expandable particles (that is, not containing the heat-expandable particles), the solid content ratio between the heat-expandable particles and the binder, and the solid content in the coating liquid were changed as shown in Table 1. A paperboard obtained in the same manner as in Example 1 except for the above.

(Comparative Example 2)
Table 1 shows the contents of the heat-expandable particles, the binder content (that is, no binder), the solid content ratio between the heat-expandable particles and the binder, and the solid content in the coating liquid. A paperboard obtained in the same manner as in Example 1 except that.

(Comparative Example 3)
Compare the base paper used in Examples 1 to 24 and Comparative Examples 1 and ^2, that is, a commercially available cardboard base paper having a basis weight of 220 g / m ² (trade name “Just K Liner” manufactured by Daio Paper Co., Ltd.). Example 3 was used. In Comparative Example 3, no coating layer (cushion layer) is provided.

(Comparative Example 4)
A commercially available nonwoven fabric having a basis weight of 50 g / m ² was defined as Comparative Example 4. In Comparative Example 4, no coating layer (cushion layer) is provided.

In addition, “basis weight (g / m ² )” in Table 1 is the basis weight of paper or paperboard after a predetermined cushion layer is provided on the base paper, and “paper and paperboard” described in JIS-P8142. It is the value measured based on "basis weight measuring method".

  Table 2 shows the results of quality evaluation, i.e., cushioning property, scratch resistance, and test for evaluating the adhesion between the base paper and the coating layer for all of these Examples and Comparative Examples. . These evaluation tests were performed under environmental conditions of temperature 23 ° C. ± 1 ° C. and humidity 50 ± 2% in accordance with JIS-P8111.

“Cushioning” in Table 2 refers to a cushion function by the cushion layer, that is, a function that softens a collision or impact that occurs between the package and the package, or a collision or impact that occurs between the paperboard and the package. Is evaluated. The coefficient of restitution was used as an index for evaluating the cushioning property, and the coefficient of restitution was calculated and evaluated according to the following procedure.
(1) As a collision object, use a flat and sturdy test stand with a flat surface, and fix the cushion layer of the test sample so that it becomes the surface. In addition, “Seglan” (45 mm thickness, specific gravity 1.6 to 1.7, surface hardness Mohs 3 to 4) manufactured by Deon Co., Ltd. was used as the top plate of the test stand.
(2) A pachinko ball (diameter 11 ± 0.01 mm, weight 5.45 ± 0.01 g) is used as a collision object on the surface of the test sample, and dropped vertically from the height of 30 cm to the test sample.
(3) The rebound when the iron ball dropped was video-recorded, and the height of the rebound was measured in mm with a ruler set in the direction of fall.
(4) The coefficient of restitution was calculated by the following formula using the measured values of the drop height and the bounce height of the iron ball.
e = √ (h / ho) (e: coefficient of restitution, ho: height of fall, h: height of bounce)
(0 ≦ e ≦ 1)
(5) That is, this restitution coefficient was used as an index of cushioning properties, and it was determined that the cushioning properties were higher as the restitution coefficient was larger.

“Scratch resistance” is an evaluation of the scratch resistance against an object to be packaged, and is based on the “Gear-proof abrasion resistance test method” described in JIS-P8136. Tested and evaluated using a testing machine. The measuring method is as follows.
(1) A resin film (0HP film) was set on the friction part of the test machine, and the test sample was placed on the sliding table so that the cushion layer of the test sample became a friction surface.
(2) A load of 500 g was applied to the test sample set on the tester sliding base, and the degree of scratches on the resin film surface when it was rubbed 200 times was visually evaluated. It was made into four steps.
(Evaluation criteria)
(Double-circle): It is superior to a nonwoven fabric.
○: Equivalent to non-woven fabric.
(Triangle | delta): It is inferior to a nonwoven fabric.
X: There is little or no improvement effect.

Furthermore, “adhesiveness between the base paper and the coating layer” means “paper and paperboard—folding strength test method—MIT test machine method” described in JIS-P8115. Number of times) The test sample after 5 times was visually evaluated, and the evaluation criteria were as follows.
(Evaluation criteria)
◎: The base paper and the coating layer are firmly adhered ○: The coating layer is slightly peeled but there is no problem Δ: The coating layer is peeled and there is a possibility of causing a problem ×: The coating layer is Completely peeled

表２に示すように、本発明に係るクッション機能を備える本紙又は板紙、すなわち実施例１〜実施例２４に係る紙又は板紙であると品質評価に優れる、すなわちクッション性、傷入り防止性、型入り防止性に優れることが分かる。

As shown in Table 2, the paper or paperboard having the cushion function according to the present invention, that is, the paper or paperboard according to Examples 1 to 24 is excellent in quality evaluation, that is, cushioning property, scratch resistance, mold It turns out that it is excellent in entering prevention property.

Claims (4)

Comprising at least a base paper and a coating layer provided by applying a coating liquid containing at least a thermally foamable particle and a binder having a glass transition temperature of 30 to 70 ° C. on at least one side of the base paper;
The thermally foamable particles are contained in the coating layer in an amount of 5 to 20% by mass in terms of solid content,
The coating layer, the thermal expandable particles and a binder, the packaging container applications of paper or paperboard having a cushioning function, characterized in that the said heat expandable particles by foaming the cushion layer by drying. The thermally foamed particles and the binder are contained in a solid content ratio of 7 to 50:93 to 50,
The coating amount of the coating liquid is 16 to 120 g / m ² in terms of solid content per side ,
In the drying process at a drying temperature of 100 to 120 ° C., the coating layer is a cushion layer, and
The coating layer packaging applications of paper or paperboard comprising a cushioning function of claim 1, basis weight and being in the range of 180~500g / m ² comprising a. Cushioning of the paper or paperboard, the coefficient of restitution used as an index of evaluation of the cushioning property, according to claim 1 or claim 2 wherein the coefficient of restitution, characterized in that a 0.40 to 0.50 Paper or paperboard for packaging containers with a cushion function. A packaging container or cushioning material using paper or paperboard for packaging containers having the cushion function according to any one of claims 1 to 3 .