JP4059371B2 - Method for producing corrugated cardboard sheet - Google Patents

Description

【００２２】
【発明の効果】
本発明による段ボールを用いれば、枚葉式のオフセット印刷マシンにより、段ボールにダイレクトにオフセット印刷することが可能となり、段ボールに美粧性の高いオフセット印刷がなしうる。また▲１▼給紙がスムースにいかない、▲２▼カールの発生、▲３▼印刷機の排紙部で紙積みしたときに不ぞろいとなる、等の各種トラブルの発生を改善することができる。なお本発明により、１００ｇ／ｍ²程度の比較的薄手の原紙で貼合したシート厚みが１．０ｍｍ程度のマイクロフルート段ボールでもオフセット印刷機にてダイレクト美粧印刷が可能である。
【図面の簡単な説明】
【図１】オフセット印刷機の概要図である。
【図２】（イ）はマイクロフルート段ボール1の潰し前の厚みＴ₁状態を示し、（ロ）はシート流れ方向の両端部の約１０ｍｍの幅を潰し処理した端部の厚みＴ₂状態を示し、（ハ）はオフセット印刷処理した後シートの厚みＴ₃状態を示したものである。
【図３】段ボールシートを所定ブランクサイズに打ち抜いた平面図で、（イ）はシート端縁の片側を幅Ｌで潰した状態を示し、（ロ）はシート端縁の両側を幅Ｌで潰した状態を示しものである。
【符号の説明】
１ 印刷処理前のマイクロフルート段ボール
２ 印刷処理した後のマイクロフルート段ボール
１０ａ、１０ｂ 上下ロール[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a corrugated cardboard sheet for printing, and in particular, a corrugated cardboard sheet excellent in offset printability.
More specifically, the corrugated cardboard sheet has improved printing workability during offset printing of micro flute corrugated cardboard sheets used in gift boxes, pizza and other food packaging boxes, and paper containers that require cosmetic printing. It relates to the manufacturing method.
[0002]
[Prior art]
As is well known, a corrugated cardboard is a material used for a packaging box, in which a liner base paper is pasted on a core having corrugated steps (flutes). Sheets made of cardboard are mainly used as container materials for product exteriors (transport packaging and unit packaging), as well as cushioning and fixing materials, pallet materials, advertising tool materials, core materials such as furniture and partitions, and for automobiles. It is also used for applications such as ceiling materials.
Incidentally, corrugated cardboard sheets are classified into A, B, and C stages according to the number of stages in the JIS standard (Z-0108). Besides this, although not defined in the standard, the E stage is widespread. The height of the step is not a standard, but is generally about 5 mm for the A step, 3 mm for the B step, 3.6 mm for the C step, and about 1.2 mm for the E step. Among these, the E stage has the same use as that of thick paperboard, and is used, for example, for gift boxes. Moreover, it is laminated | stacked with the thing with a high step height, and may be used as a double-sided cardboard sheet | seat.
In recent years, corrugated cardboard has been developed and used, which has a larger number of stages than E stage and has a lower height of 0.4 to 1.0 mm, such as F stage, G stage, N stage, mini cardboard, micro flute cardboard, etc. being called. Such micro flute corrugated cardboard is beginning to be used as a material for general paper containers, four-corner paper trays, and the like.
[0003]
Corrugated cardboard sheets are usually produced by forming single-sided corrugated cardboard at a single facer section, and then bonding a liner base paper on the other front side at the double facer section. After this, the sheet is cut after being dried under pressure on a hot plate. Thus, corrugated cardboard is a structure in which a corrugated core is sandwiched with a liner, so it is lighter and more rigid than paperboard. Therefore, the paper container made of the above-mentioned micro flute corrugated cardboard has an advantage that a lightweight paper container can be obtained as compared with a paper container made of the same rigid board.
In addition, micro flute corrugated cardboard has the characteristic that the corrugation is inconspicuous, and is suitable for product boxes that require beautiful and highly accurate surface decoration such as gift boxes, individual packaging boxes, and interior boxes. .
[0004]
Printing on the cardboard surface is often performed by a flexographic printing machine (flexographic printer slotter). When corrugated cardboard is used for gift wrapping, individual packaging or interior decoration, precise and beautiful printing (decorative) is required, so flexographic printing or gravure printing (both winding type) on the winding liner, and using a corrugator It is performed by the pre-printing method that cuts one by one after bonding. In some cases, offset printing (sheet-fed type) on paper and gravure printing are pasted on a single-sided cardboard one by one (sheet-fed bonding).
Flexographic printing is suitable for relatively rough printing, and multicolor printing is possible. However, flexographic printing is not suitable for so-called full-color printing, so it is suitable for printing a case where the printing cost is to be kept low, for example, a cardboard box for exterior use. On the other hand, the pre-printing method and the sheet-fusing method print at the liner stage, so the cosmetics are higher than the sheet printing, but these printing methods are more time-consuming than the direct printing on the corrugated cardboard sheet and lack high speed. There was a problem that the material cost was high.
[0005]
[Problems to be solved by the invention]
Micro flute corrugated cardboard used for multi-product, small-lot gift wrapping, individual packaging, interior purposes, or advertising tool materials requires precise and highly cosmetic printing, so it can be offset directly on the sheet surface It is hoped that. However, most of the offset printing machines used for printing on paper containers are machines exclusively for paperboard, and most of them are of a sheet feeding type (sheet feed) as a base paper supply method. In addition, there are currently no roll-off offset printing machines in Japan.
Therefore, when printing was performed on the micro flute corrugated cardboard using the above-mentioned sheet-fed offset printing machine, as described below, (1) paper feeding does not go smoothly, (2) curl generation, (3) Various troubles such as irregularities occurred when the paper was stacked in the paper discharge section of the printing press.
[0006]
The present inventors have studied the structure of the offset printing machine in order to solve the above-mentioned troubles, and have investigated the cause of the trouble.
According to the results of the study by the present inventors, the problem of “a phenomenon that cannot be taken well one by one” in the sheet feeder of the printing press and “the gripping claw of the printing unit part cannot be gripped” is a thick cardboard. It turned out to happen. That is, the conventional sheet-fed offset printing press for paper containers has an allowable range of base paper thickness of 0.3 to 0.8 mm, so that thick cardboard of A, B, and C stages cannot be used. It has been found that micro flute corrugated cardboard developed in recent years has the same problems as described above when the thickness of the entire sheet is 1 mm or more.
[0007]
As shown in FIG. 1, the offset printing machine takes out the laminated paperboard blanks one by one from the upper surface by vacuum soccer with a suction cup, and then picks up the edge of the sheet with a gripping nail, Transfer to the printing unit. Therefore, if you look at the printed paper, you will see a slight dent on the front side of the paper. This is called the “barking side”. The rear side is called “barking ass”. You can tell in which direction the paper was fed to the printing machine by the trace of the tail. In the above-mentioned printing press, a base paper having a sheet thickness of 1 mm or more is poorly fed and causes trouble. The part where the gripper holds the sheet is about 10 mm from the leading end of the sheet, and the printing pressure is applied 10 to 20 mm behind the gripped part (end). Therefore, it has been found that if the sheet edge portion of about 10 to 20 mm can be thinned to about 0.3 to 0.8 mm (optimally 0.55 mm or less), the trouble of feeding in the offset printing machine is reduced.
[0008]
As shown in FIG. 1, the offset printing method transfers ink onto the plate surface, then transfers the ink on the plate to a rubber cylinder called a softer blanket, and then the ink on the blanket. Is transferred to paper sandwiched between impression cylinders. When printing on corrugated board with an offset printing machine, if the printing pressure is increased and the ink is not transferred by applying printing pressure to the total thickness of the back liner, core, and front liner, the part of the cover corresponding to the valley of the step Ink is not applied to the ink, and printing blurring occurs, or a washing plate-like step appears (remarkably appears on a base paper having a front liner of 140 g / m ² or less). When the printing pressure is increased, the micro flute corrugated cardboard sheet is “squeezed” by the blanket and the impression cylinder, except for the grip part of the sheet of 10 to 20 mm at the leading end in the traveling direction. In many cases, it becomes a state, and the step is crushed and thinned, and at the same time, it is rounded and curled.
[0009]
Further, continuously printed sheets are stacked in a paper discharge (delivery) unit of the printing press. Usually, about 1000 to 1500 sheets are stacked. If the gripping portion is 0.2 mm thick, for example, the stacked seat blocks are inclined by 200 to 300 mm. Therefore, it is necessary to remove the frame every 500 sheets or adjust the height by applying a pad, which is a problem in terms of workability and efficiency. In addition, the printed micro flute corrugated cardboard must be drawn into a prescribed shape to make a paper container. Although the work is performed by a punching machine, it is very difficult to feed the inclined sheet block, and the punching registration is easily shifted. Also, when scraping a punched sheet, it is difficult and causes problems in the entire processing process.
Accordingly, the present invention proposes a method for manufacturing a corrugated cardboard sheet capable of performing offset printing directly on the sheet surface for the purpose of solving the above-mentioned problems.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, a liner base paper is bonded to both sides of a core base paper that has been step-formed, and a step height obtained by sheet cutting after the bonding is 1.00 mm or less, and the number of steps per 30 cm is 90 or more. In a flute double-sided cardboard sheet, after bonding, before printing, the steps are crushed by using a pressing means so that the thickness of both ends 10 mm in the flow direction of the double-sided cardboard sheet is 0.3 mm to 0.8 mm. A method for producing a corrugated cardboard sheet for printing, which is excellent in offset printability , characterized by offset printing after crushing a step. Claim 2 of the present invention, the corrugated sheet thickness is 0.7～1.1Mm, mashed thickness portions of the printing cardboard sheet according to claim 1 which is 0.3~0.55mm It is a manufacturing method. Claim 3 of the present invention, a paper container or cardboard sheets for advertising tool the cardboard sheet produced becomes subjected to offset printing by the method of claim 21 to wherein.
[0011]
The pressurizing means for the corrugated cardboard sheet may be pressed by upper and lower rolls, or may be arbitrarily selected according to the situation by pressing by a lithographic press. In addition, the pressurization may be performed in the process until the offset printing is performed after the corrugated cardboard sheet is bonded, and therefore the pressurizing means may be provided in the corrugated cardboard bonding machine or provided outside the bonding machine. May be.
[0012]
The portion to be crushed is a belt-like region having a constant width in the vicinity of the short edge portion of the sheet, and may be crushed only on one side as shown in FIG. 3 (a) or crushed on both sides as shown in FIG. 3 (b). The crushing width L is preferably 10 mm or more. Even if crushing exceeds 20 mm, there is not much meaning for the above-described purpose.
Moreover, it may be crushed in a direction parallel to the flow of the stage, or may be crushed in a vertical direction (machine traveling direction). In some cases, the sheet can be crushed on the corrugator before cutting the sheet.
If the thickness of the crushed portion is 0.8 mm or less as described above, it is compatible with the current offset printing machine, but in order not to cause a problem with more printing machines, 0.3 to 0.55 mm. It is more preferable to crush to the thickness of.
[0013]
[Action]
According to the method of the present invention, it is possible to perform offset printing directly on a corrugated cardboard by a sheet-fed offset printing machine, and therefore, precise and highly beautiful printing can be achieved. Also, there is no occurrence of various troubles such as (1) paper feeding is not smooth as in the past, (2) curling, and (3) unevenness when stacked in the paper discharge section of the printing press. .
By adopting this method, direct cosmetic printing can be performed with a so-called offset printing machine even with a micro flute corrugated cardboard having a thickness of about 1.0 mm bonded with a relatively thin base paper of about 100 g / m ² .
In the present specification, the term “micro flute corrugated cardboard” refers to a corrugated cardboard having a corrugated height of 1 mm or less and 90 corrugated boards per 30 cm.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described. A preferred embodiment of the present invention is intended for corrugated cardboard having a higher number of stages than the E stage, specifically, a corrugated cardboard sheet having a height of 1 mm or less and a number of stages of 90 or more per 30 cm; It is intended for micro flute corrugated cardboard characterized by having 55 or less and 120 or more steps. In terms of sheet thickness, a main target is a corrugated cardboard sheet of 0.7 to 1.1 mm.
[0015]
[Example 1]
Hereinafter, the present invention will be described specifically by way of examples.
As the front / center / back liner of micro flute with double-sided corrugated cardboard structure, “Glossy bleached craft 100g / m ² ”, “Both bleached craft 100g / m ² ”, “Both bleached kraft 100g / m ² ” Was selected and bonded with a corrugator for cardboard.
First, the core: “Both exposed kraft 100 g / m ² ” was molded with a corrugated roll with a step height of 0.5 mm and a number of hills of 155 / (per 300 mm). After the paste used for the cardboard for the exterior is transferred with a glue roll, it is bonded to the backing liner base paper “both exposed kraft 100 g / m ² ”. After that, after discharging to the bridge part with a take-up conveyor, the glue used for normal exterior cardboard mainly composed of corn starch is transferred to the top of the step by a separately prepared glue machine, and then the front liner base paper `` Glossy gloss after bonding kraft 100 g / m ² ", to produce a micro-flute corrugated cardboard first heat bonded sided corrugated cardboard structure at a surface temperature of 120 ° C. to 180 ° C. at the hot plate unit.
After drying, the micro flute corrugated cardboard 1 having the thickness T ₁ shown in FIG. 2 (a) is microscopically moved by the upper and lower rolls 10a and 10b set at a roll clearance of 0.4 mm as shown in FIG. 2 (b). After crushing the width of about 10 mm at both ends of the flute corrugated cardboard 1 in the sheet flow direction, the double-sided cardboard was punched into a predetermined rectangular size with a slitter and a cutter. The thickness T ₂ of the end portion after crushing was 0.5 mm. The sheet thickness T _{1 of the} portion that was not crushed was 0.75 mm.
Further, the portion subjected to the crushing processing of the sheet was set on the holding side of the paper feeding unit of the offset printing machine, printed on the front liner surface, and then punched into a predetermined blank size by a separately prepared punching machine. The thickness T ₃ of the sheet 2 after printing was 0.60 mm.
The double-sided corrugated cardboard blank punched out by the above method has no particular problem in the required characteristics such as box making, although each constituent base paper has a low rice paper weight as compared with the single paper board.
[0016]
[Example 2]
Select “Glossy Craft 100g / m ² ”, “Both Exposed Craft 80g / m ² ” and “Both Exposed Craft 100g / m ² ” as the front liner / core / back liner of the micro flute with double-sided cardboard structure And it bonded by the corrugator for cardboards. The difference from Example 1 is that the step height at the time of step forming is 0.6 mm and the number of steps is 120 per 300 mm. In this example, the thickness of the end portion after crushing of the sheet was 0.55 mm. The sheet thickness of the portion not subjected to the crushing process was 0.82 mm. As for the crushing part, the width of about 10 mm at both ends in the sheet flow direction of the micro flute corrugated cardboard 1 is crushed by the upper and lower rolls 10a and 10b set to a roll clearance of 0.45 mm, and set to the holding side of the paper feeding unit. In printing, it was possible to print without problems as in the first embodiment.
[0017]
[Example 3]
Corrugator for corrugated board, selecting “coated ball 190 g / m ² ”, “core base paper 115 g / m ² ” and “liner 160 g / m ² ” as the front liner / core / back liner of the micro flute having a double-sided cardboard structure. Was formed with a step roll having a step height of 0.5 mm and a number of steps of 155 / (per 300 mm), and bonded in the same manner as in Example 1. On the way, it was crushed to a clearance of 0.65 mm with a crushing roll. In this example, the thickness of the uncrushed sheet was 0.96 mm. As a result of the crushed portion having a thickness of 0.75 mm, the offset printing can be performed without any problem as in the first embodiment.
[0018]
[Comparative Example 1]
Select “Glossy Craft 100g / m ² ”, “Both Exposed Craft 80g / m ² ” and “Both Exposed Craft 100g / m ² ” as the front liner / core / back liner of the micro flute with double-sided cardboard structure And it bonded by the corrugator for cardboards. The difference from Example 1 is that the step height at the time of step forming is 0.6 mm and the number of steps is 120. In this case, the thickness of the sheet was 0.82 mm. In particular, since no squeezing is performed, the phenomenon of “double”, which is one of paper feeding failure and printing failure, appears in offset printing.
[0019]
[Comparative Example 2]
Corrugator for corrugated board by selecting “Coated ball 190 g / m ² ”, “Core base paper 115 g / m ² ” and “Liner 160 g / m ² ” as the front liner / core / back liner of the micro flute with double-sided corrugated cardboard structure. And pasted. There was no crushing process. In this case, the thickness of the sheet was 0.96 mm. Since the base paper, in particular, the front liner base paper is relatively thick and paperboard, the color development was good in offset printing, but the phenomenon of paper feeding error was the same as in Comparative Example 1.
[0020]
The following table shows the feed suitability and the effect of the direct printing finish in the offset printing machine performed for the examples and comparative examples of the present invention.
[0021]
[Table 1]

[0022]
【The invention's effect】
By using the corrugated cardboard according to the present invention, it becomes possible to perform offset printing directly on the corrugated board by a sheet-fed offset printing machine, and offset printing with high cosmetics can be performed on the corrugated cardboard. In addition, it is possible to improve the occurrence of various troubles such as (1) paper feeding is not smooth, (2) curling, and (3) unevenness when stacked in the paper discharge section of the printing press. . In addition, according to the present invention, direct cosmetic printing can be performed with an offset printing machine even with micro flute corrugated cardboard having a sheet thickness of about 1.0 mm bonded with a relatively thin base paper of about 100 g / m ² .
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an offset printing machine.
FIG. 2 (a) shows the thickness T ₁ state before crushing of the micro flute corrugated cardboard 1, and (b) shows the thickness T ₂ state of the end portion obtained by crushing the width of about 10 mm at both ends in the sheet flow direction. (C) shows the thickness T ₃ state of the sheet after the offset printing process.
FIG. 3 is a plan view of a cardboard sheet punched into a predetermined blank size. (A) shows a state in which one side of the sheet edge is crushed with a width L, and (B) shows a state in which both sides of the sheet edge are crushed with a width L. It shows the state.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Micro flute corrugated cardboard before printing process 2 Micro flute corrugated cardboard 10a, 10b up and down roll after printing process

Claims (3)

In a microflute double-sided corrugated cardboard sheet having a step height of 1.00 mm or less and a number of steps per 30 cm of 90 or more , the liner base paper is pasted on both sides of the core core paper that has been step-formed, and the sheet is cut after pasting.
After pasting and before printing, after crushing the step using pressure means so that the thickness of 10 mm width at both ends in the flow direction of the double-sided cardboard sheet is 0.3 mm to 0.8 mm, A method for producing a corrugated cardboard sheet having excellent aptitude for offset printing , characterized by performing offset printing . The method for producing a corrugated cardboard sheet for printing according to claim 1 , wherein the corrugated cardboard sheet has a thickness of 0.7 to 1.1 mm, and the crushed portion has a thickness of 0.3 to 0.55 mm. Shiki or advertising tool for cardboard sheet to the corrugated sheet manufactured by the method according to any one of claims 21 to become subjected to offset printing.

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