JP2009084745A - Processed paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain processed paper, without neither fold breakage or fluffing when subjected to crease processing, and suitable as a material for containers or boxes made of paper and creased. <P>SOLUTION: The processed paper contains 0.1-2 wt.% of a 3-5C polyhydric alcohol, preferably glycerol, in base paper mainly consisting of a woodpulp fiber. A method for adding the polyhydric alcohol is preferably a coating or impregnation method using an ordinarily used coater such as a size press coater, gate roll coater, rod metering size press coater, or curtain coater. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a processed paper suitable for a material of a paper container for forming with crease or a paper box for box making.

  In recent years, liquid paper containers mainly made of paper have been used from the viewpoint of environmental problems, recycling, and resource saving.

  These liquid paper containers are mainly made of paper that uses bleached pulp (bleached pulp) and a thermoplastic resin typified by polyethylene or laminated aluminum foil as the base material. Heat-sealed to make a paper liquid container.

  Since the paper used in these liquid containers undergoes a processing step, some performance is required. One of them is crease suitability. The liquid paper container is made by folding on a crease line at the time of processing, but there is a problem that the pulp fiber breaks on the line to be folded at that time, and fluffing and cracking occur. Since the purpose of the liquid paper container is to protect the contents, the condition is that no fuzz or cracking occurs during processing.

  Many paper containers and paper boxes are used as containers and boxes for packaging various articles. These paper containers and boxes are made by folding, bonding or assembling a blank at a predetermined location, and the blank is usually provided with a size so that the blank can be folded at a precise position as designed. A crease is stamped at the bent portion (for example, Patent Document 1).

Japanese Utility Model Publication No. 63-3920

  The crease stamped on the blank needs a certain depth in order to bend the blank accurately and easily. There was a problem to do.

  An object of the present invention is to provide a processed paper suitable for the material of a paper container into which crease is formed and a paper box to be boxed, which has good crease suitability and does not generate fuzz and cracks.

  Said subject was solved by containing C3-C5 polyhydric alcohols, such as glycerol, in 0.1 to 2 weight% with respect to the base paper containing a wood pulp fiber.

  According to the present invention, it is possible to provide a processed paper that has good crease suitability and does not generate fuzz and breakage, and a paper container or a paper box can be provided using the processed paper.

  In the processed paper of the present invention, the content of the polyhydric alcohol having 3 to 5 carbon atoms needs to be in the range of 0.1 wt% to 2 wt% with respect to the base paper. When the content of the polyhydric alcohol is less than 0.1% by weight, the improvement of the crease suitability is insufficient, and when it exceeds 2% by weight, the paper strength is significantly reduced. The reason why polyalcohol improves crease suitability is not clear, but the polyhydric alcohol present between the fibers of the pulp slightly reduces the interfiber bond and causes slippage between the fibers, resulting in improved crease suitability. It is inferred that

  As the polyhydric alcohol having 3 to 5 carbon atoms, glycerin, propylene glycol, 1,3-butylene glycol, erythritol, and xylitol are preferable, and glycerin is particularly preferable.

  As a method of incorporating the polyhydric alcohol into the paper substrate, a method of coating or impregnating is preferable. Specifically, a commonly used coating machine such as a size press coater, a gate roll coater, a rod metering size press coater, or a curtain coater may be used. In addition, a surface treatment agent other than glycerin may be mixed and applied or impregnated for the purpose of imparting surface strength and sizing properties within a range not deteriorating dimensional stability. Examples of the surface treatment agent include water-soluble polymers such as polyvinyl alcohol, polyacrylamide, starch, and modified starch. Further, a surface sizing agent such as styrene / acrylic resin, styrene / maleic acid resin, styrene / methacrylic acid resin, olefin resin, or ester resin may be mixed and used.

  The base paper used in the present invention is mainly composed of wood pulp fibers. Specifically, it is produced by tangling and sticking plant fibers or plant fibers and other fibers, and is produced by a known method in the papermaking field. Examples of plant fibers include wood pulp fibers such as conifers or hardwoods, bast fibers such as Mitsumata and Kozo, non-wood fibers such as bagasse, kenaf and hemp, cotton fibers and waste paper. Examples of fibers other than plant fibers include synthetic fiber pulps such as polyethylene fibers, polypropylene fibers, nylon fibers, and polyester fibers, inorganic fibers such as glass fibers and rock wool fibers, and metal fibers such as stainless fibers. From the viewpoint of waste disposal and environmental burdens against the background of global environmental problems, paper made of 100% plant fiber is preferred.

  Specifically, chemical pulp using conifers, hardwoods, etc. as wood pulp fibers; bleached kraft pulp of softwood, unbleached kraft pulp, bleached kraft pulp of hardwood, unbleached kraft pulp, mechanical pulp; groundwood pulp (GP), refiner mechanical pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), etc., deinked pulp (DIP), etc., and these may be used alone or in any proportions Is done. The deinked pulp is also called regenerated pulp. In the present invention, among them, softwood bleached kraft pulp (hereinafter referred to as NBKP) or hardwood bleached kraft pulp (hereinafter referred to as LBKP) is preferable in terms of water content and versatility. In addition, when the content of LBKP exceeds 70% by weight with respect to the total fiber component, cracking is likely to occur during crease processing. However, in the present invention, cracking occurs even when the content of LBKP exceeds 70% by weight. Generation can be suppressed.

  As a method for producing paper, generally, the above-mentioned wood pulp fiber, water, and a paper material prepared by adding a filler or other chemicals as necessary are sprayed onto the wire of a paper machine, and the wire After dehydration in the part, squeezing in the press part, drying in the dryer part, if necessary, size paper that gives strength and water resistance to the paper and calendering that adjusts the unevenness of the paper surface are made, and paper is made. The finished paper is wound and finished to a predetermined winding dimension. Further, in order to impart paper strength and water resistance to paper, chemicals such as polyvinyl alcohol, starch, and surface sizing agent may be used alone or in appropriate combination of two or more. The production of paper in the present invention is not limited to this.

  In the base paper used in the present invention, the filler may be blended without blending, and it is desirable to blend without filler because it affects foaming properties, but it may be blended from the viewpoint of increasing opacity. A filler generally used in the papermaking field can be used as the filler, and is not particularly limited. For example, clay, calcined kaolin, delaminated kaolin, heavy calcium carbonate, light calcium carbonate, light calcium carbonate-silica composite, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, water Inorganic fillers such as aluminum oxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide, and organic fillers such as urea-formalin resin, polystyrene resin, phenol resin, and fine hollow particles are used alone or in appropriate combination of two or more. . In addition, in acid papermaking, a filler obtained by removing acid-soluble ones from the filler used in the neutral papermaking is used, and these are used alone or in combination of two or more.

  Further, the base paper used in the present invention can be internally or externally added with a sizing agent. In the case of acidic papermaking, the sizing agent may be a rosin sizing agent, a rosin emulsion sizing agent, an alpha carboxymethyl saturated fatty acid, or the like. On the other hand, in the case of neutral papermaking, rosin sizing agents for neutral papermaking, alkyl ketene dimers, alkenyl succinic anhydrides, and cationic polymer sizing agents can be used.

  In addition, various nonionic, cationic or amphoteric yield improvers, paper additive improvers, paper strength aids, and the like used in the past are appropriately selected and used as necessary. The Further, for example, basic aluminum compounds such as sulfuric acid band, aluminum chloride, sodium aluminate, basic aluminum chloride and basic polyaluminum hydroxide, water-soluble aluminum compounds such as water-degradable alumina sol, sulfuric acid A polyvalent metal compound such as ferrous sulfate or ferric sulfate, silica sol, or the like may be internally added.

  Other papermaking aids such as various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamine resin, polyethyleneimine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, hydrophilic cross-linked polymer particle dispersion And various compounds such as derivatives or modified products thereof.

  Furthermore, internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be appropriately added depending on the intended use.

  Further, talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, and titanium dioxide may be added to the pulp as a filler. If necessary, chemicals normally used in the paper making process, for example, paper strength enhancers, sizing agents, antifoaming agents, colorants and the like are added to these stocks to make a base paper.

  There is no particular limitation on the type of paper machine for making the base paper of the present invention, such as a long net paper machine, a twin wire paper machine, a circular net paper machine, a gap former, a hybrid former (on-top former), etc. The paper can be made with a known paper machine. The press line pressure is used within the normal operating range. Further, for the purpose of imparting smoothness and improving printability, a calendar process may be performed. The calendar is used at a linear pressure within the normal operating range, but in the present invention, the paper is more preferably bulky from the viewpoint of evaporating moisture, and in that case, the range in which the smoothness of the paper can be maintained. Therefore, low linear pressure or bypass is preferable. A soft calendar is preferable to a normal calendar.

Moreover, although there is no restriction | limiting in particular in the basic weight of the said base paper, this invention can demonstrate the effect by applying to the paper of the basic weight 50-500 g / m < ² > normally used for box making. it can.

  Further, this base paper may be subjected to surface sizing treatment using starch, polyvinyl alcohol, polyacrylamide or the like using a size press, a gate roll coater, or a pre-metering size press.

  Further, a pigment coating layer composed of at least a pigment and a binder may be provided on at least one side of the base paper. By providing the pigment coating layer, it is possible to impart aesthetics and clearness in printing and increase the commercial value.

  In the present invention, the pigment coating layer preferably has a pigment / binder solids weight ratio of 100/15 to 100/30. If the pigment / binder solids weight ratio is less than 100/15, the strength of the coating layer is so low that it cannot withstand the compressive stress applied to the coating layer during crease processing, and the coating layer will crack. It becomes easy. Further, since the adhesive force between the coating layer and the base paper is low, peeling occurs at the interface between the base paper and the coating layer, and peeling from the resin laminate layer due to the falling off of the coating layer is likely to occur. On the other hand, if the solid weight ratio of pigment / binder is higher than 100/30, the coating layer has sufficient strength, but the flexibility (cushioning) and smoothness of the coating layer are lost, so it is suitable for crease. In addition, printability is reduced.

  The binder used for the pigment coating layer is preferably a synthetic resin. Specifically, styrene / butadiene copolymer, styrene / acrylonitrile copolymer, styrene / acrylic copolymer, acrylic ester copolymer, acrylic copolymer, ethylene / vinyl acetate copolymer, Aqueous emulsions such as vinyl acetate copolymers can be used alone or in admixture of two or more thereof.

  Further, as a binder other than the synthetic resin, a small amount of a water-soluble binder such as starch, polyvinyl alcohol, and casein may be used, but the flexibility (cushioning property) and smoothness of the coating layer are lowered, and as a result, the crease suitability and Since the gravure printability is lowered, it is not preferable to use a large amount.

  As pigments used in the pigment coating layer, various conventionally used pigments such as kaolin, delaminated kaolin, engineered kaolin, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, Inorganic pigments such as calcium sulfate, silicic acid, silicate, colloidal silica, and satin white, and organic pigments such as plastic pigments and binder pigments can be used alone or in admixture of two or more.

  In addition, you may add suitably a dispersing agent, a water-proofing agent, a lubricant, an antifoamer, an antiseptic | preservative, dye, etc. in the coating liquid for providing a pigment coating layer as needed.

The coating amount of the pigment coating layer is preferably 10 g / m ² or more and 30 g / m ² or less. If the coating amount is less than 10 g / m ² , the covering property of the base paper is not sufficient, so that the required printability cannot be obtained. When the coating amount exceeds 30 g / m ² , the coating layer becomes thick. Therefore, when the curling process is performed so that the coating layer becomes the inner side during processing, the inner curling amount is equal to the thickness of the coating layer. Since the radius is small, the compressive stress applied to the coating layer increases, the buckling of the coating layer is likely to occur, and the resin laminate layer is easily peeled off.

The basis weight of the processed paper provided with the pigment coating layer configured as described above is preferably 150 g / m ² or more because paper strength and rigidity are required for its use. On the other hand, if the basis weight is too large, the curl process is performed so that the coating layer is on the inner side during top curl processing, and the radius of the inner curl becomes smaller by the thickness of the base paper. The applied compressive stress increases, the buckling of the coating layer is likely to occur, and the paper powder is likely to be generated due to the falling off of the coating layer. Therefore, it is preferably 400 g / m ² or less.

  In the present invention, after the pigment coating layer is provided on the base paper as described above, a calendar treatment may be performed to smooth the surface of the pigment coating layer. However, if the surface of the coating layer has sufficient smoothness without performing calendering and good gravure printing suitability can be obtained, calendering is not necessary.

  The processed paper of the present invention is suitably used for cup base paper and paper tray base paper, and can also be applied to other food and industrial packaging materials and paper containers.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these. In addition,% of an Example and a comparative example shows weight%. Further, the crease suitability of the obtained processed paper was evaluated by the following method, and the results are shown in Tables 1 and 2.
<Cleasability>
Using the THE PATRA CARTON BOARD CREASER (HEADLAND WORKS LTD), the processed paper obtained in the example and the comparative example is placed on a female mold having a groove having a width of 2 mm, and a width of 1.3 mm is provided at a position corresponding to the groove of the female mold. After pressing the male mold with crisp teeth against this and pressing the male crease teeth to a depth of 100μm to crease, bend 180 degrees so that the crease processing side becomes a mountain, visually Fiber fluffing and cracking were evaluated.
◎: Fiber fluff and cracks do not occur on the entire surface of the folded line ○: Fluff is slightly generated in part △; Fiber fluff and cracks occur at half or more of the length on the folded line ×: Bending In addition, fiber fluffing and cracking occur on the entire surface of the wire, and there is no problem in performance as long as it is greater than or equal to ○ in the above evaluation.

[Example 1]
Mix 10 parts of softwood bleached kraft pulp (NBKP; Canadian standard freeness (CSF) 600 ml) and 90 parts of hardwood bleached kraft pulp (LBKP; CSF 400 ml), and add it to the pulp raw material of CSF 420 ml after mixing. A raw material with a pH of 4.5 is added to a raw paper machine by adding 1.25% sulfuric acid band, 0.5% rosin sizing agent and 0.2% polyacrylamide as a paper strength agent to the dry weight of pulp as a solid content. Single-layer papermaking was performed at a speed of 100 m / min to produce a paper sheet having a basis weight of 250 g / m ² .
Subsequently, the obtained paper web was subjected to a two-roll size press using a coating solution containing oxidized starch (solid content concentration 2%) and glycerin (solid content concentration 3%) at an absolutely dry coating amount of 5.0 g / m ^2. (Oxidized starch dry coating amount 2.0 g / m ² , glycerin absolute dry coating amount 3.0 g / m ² ), dried with an infrared dryer, calendar at a linear pressure of 30 kgf / cm Processing was carried out to obtain a processed paper.

[Example 2]
The solid content concentration of glycerin is 5% by weight, and the absolute dry coating amount is 7.0 g / m ² (the absolute dry coating amount of oxidized starch is 2.0 g / m ² , the absolute dry coating amount of glycerin is 5.0 g / m ² ). Except for the above, processed paper was obtained in the same manner as in Example 1.

[Example 3]
Other than setting the glycerin concentration to 1% by weight and the absolute dry coating amount to 0.75 g / m ² (the absolute dry coating amount of oxidized starch 0.5 g / m ² , the absolute dry coating amount of glycerin 0.25 g / m ² ) Obtained a processed paper in the same manner as in Example 1.

[Example 4]
A processed paper was obtained in the same manner as in Example 1 except that polyvinyl alcohol (PVA) was used instead of the oxidized starch used in Example 1.

[Example 5]
In a gate roll coater (GRC), oxidized starch (solid content concentration 2%) and glycerin (solid content concentration 3%) were 5.0 g / m ² (oxidized starch coating amount 2.0 g / m ² , A sample was obtained in the same manner as in Example 1 except that the coating was performed so that the absolute dry coating amount was 3.0 g / m ² ).

[Example 6]
Calender size, coating solution containing oxidized starch (solid content concentration 2%) and glycerin (solid content concentration 3%) is 5.0g / m ² (absolute dry coating amount of oxidized starch 2.0) A processed paper was obtained in the same manner as in Example 1 except that coating was performed so that the dry coating amount of g / m ² and glycerin was 3.0 g / m ² .

[Example 7]
In a rod metering size press (RMSP), a coating liquid containing oxidized starch (solid content concentration 2%) and glycerin (solid content concentration 3%) was subjected to an absolutely dry coating amount of 5.0 g / m ² (of oxidized starch). A processed paper was obtained in the same manner as in Example 1 except that coating was performed so that the absolute dry coating amount was 2.0 g / m ² and the glycerin absolute dry coating amount was 3.0 g / m ² .

[Example 8]
A processed paper was obtained in the same manner as in Example 1 except that 30 parts of softwood bleached kraft pulp (NBKP; Canadian standard freeness (CSF) 600 ml) and 70 parts of hardwood bleached kraft pulp (LBKP; CSF 400 ml) were used.

[Example 9]
Implemented except that the oxidized starch used in Example 1 was set to 0, and the coating liquid containing only glycerin (solid content concentration 3%) was coated so that the dry coating amount of glycerin was 3.0 g / m ^2. A processed paper was obtained in the same manner as in Example 1.

[Comparative Example 1]
Implemented except that the amount of glycerin added to the size press solution was 0, and the coating solution containing only oxidized starch (solid content concentration 2%) was applied so that the dry coating amount of oxidized starch was 2.0 g / m ^2. A processed paper was obtained in the same manner as in Example 1.

[Comparative Example 2]
The same as in Example 4 except that the amount of glycerin added to the size press solution was 0, and the coating solution containing only polyvinyl alcohol (solid content concentration 2%) was 2.0 g / m ^2. A sample was obtained.

[Comparative Example 3]
A processed paper was obtained in the same manner as in Example 1 except that the size press solution was water.

[Comparative Example 4]
A processed paper was obtained in the same manner as in Example 1 except that glycerin in the size press solution was changed to sorbitol (absorbed sorbitol coating amount 3.0 g / m ² ).

[Comparative Example 5]
A processed paper was obtained in the same manner as in Example 1 except that glycerin in the size press solution was changed to polyethylene glycol (absolute dry coating amount of polyethylene glycol 3.0 g / m ² ).

表１に示されるように、グリセリンを基紙に対して0.1〜2％の範囲で含有させた実施例１〜９の加工用紙はクリース適性が良好であった。これに対して、表２に示されるように、ソルビトールを含有させた比較例４、ポリエチレングリコールを含有させた比較例５はクリース適性が劣っていた。

As shown in Table 1, the processed paper of Examples 1 to 9 containing glycerin in the range of 0.1 to 2% with respect to the base paper had good crease suitability. On the other hand, as shown in Table 2, Comparative Example 4 containing sorbitol and Comparative Example 5 containing polyethylene glycol were inferior in crease suitability.

Claims (3)

  A processed paper in which a polyhydric alcohol having 3 to 5 carbon atoms is contained in a base paper containing wood pulp fibers, and the content of the polyhydric alcohol is 0.1% by weight or more and 2% by weight or less with respect to the base paper Processed paper characterized by being.   The processed paper according to claim 1, wherein the content of hardwood bleached kraft pulp in the base paper is 70% by weight or more based on the total fiber components.   The processed paper according to claim 1 or 2, wherein the polyhydric alcohol is glycerin.