JP2008240208A - Method for producing waste paper pulp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which even inkjet recording paper of multilayer constitution can easily be disintegrated and recycled as waste paper pulp. <P>SOLUTION: The method for producing the waste paper pulp comprises adding a disintegration promoter in an amount of 100-1,000 ppm based on inkjet recording paper as a waste paper raw material thereto and pulping the inkjet recording paper. Furthermore, the inkjet recording paper is provided with at least two or more layers of coating layers obtained by coating at least one surface of a support with a coating liquid containing a pigment and a binder. Paper comprises the waste paper pulp. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing waste paper pulp (recycled pulp) using ink jet recording paper as a raw paper raw material.

In recent years, the reuse of waste paper has been increasing. Paperboard, newsprint, and general printing paper have been established as used paper, but inkjet paper coated with silica or alumina as a pigment is difficult to dissociate and is difficult to use as used paper material There is. In the present invention, disaggregation means that used paper or waste paper is unwound and made into a slurry.
In general, mechanical processing has been performed for disaggregation of paperboard, newsprint, general printing paper, and waste paper. That is, waste paper soaked in treatment agents such as water and deinking agents or chemicals such as sodium hydroxide and sodium hypochlorite is dispersed in pulp fibers, fillers, printing inks, etc. by mechanical stress such as pulper. After that, it is sent to a foreign matter removing process such as a coarse screen. Further, in the case of unprinted damaged paper (also referred to as broke) generated in a paper mill, it is reused again in the factory as a papermaking raw material after the disaggregation process.

By the way, in recent years, the progress of inkjet printers is remarkable, and in particular, high-quality inkjet printers called phototypes use light-colored inks in addition to the four colors CMYK, so that printed matter with an image quality close to silver salt photography can be obtained. It has become.
With the increase in the speed of ink jet printers and the increase in the number of ink colors, the quality required for ink jet recording media has become stricter. In general, ink jet recording media are required to absorb a large amount of ink promptly, so that ink reception composed of a porous pigment such as silica and a binder resin is considered in consideration of ink absorption and ink bleeding. A layer is provided, and a dry coating amount of the ink receiving layer is increased (for example, see Patent Document 1).

  In addition, in order to increase the ink absorption capacity, many ink receiving layers have two or more layers. In such a multilayer ink jet recording medium, particularly high ink absorbability and strength are required for the lower coating layer. That is, if the ink absorbency of the coating layer is insufficient, it is difficult to supplement the ink absorbency of the upper layer. In addition, if the strength of the coating layer is weak, not only will there be operational problems, but the strength of the recording layer in the final product will also be weak, and the amount of paper dust will increase during cutting, which will adversely affect the transportability of the inkjet printer. It becomes easy.

In addition, as described above, there are many cases in which ink-jet recording paper is required to have a photographic glossiness, and as a glossy ink-jet recording medium, a super calendering process is applied to smooth the surface of the ink receiving layer and impart gloss. The surface of the drum (cast drum) on a heated mirror surface with a brightening agent applied to the resurface of the ink-receiving layer, or a wet or plastic ink-receiving layer. There are those manufactured by a casting method in which the mirror surface is copied onto the surface of the recording paper at the same time as being dried after being pressed (see, for example, Patent Documents 2 and 3).
On the other hand, in order to improve the strength of the coating layer, the amount of the binder is increased.

JP-A-10-235994 JP-A-62-95285 JP 62-235994 A

  Ink jet recording paper having a multilayer ink receiving layer requires high ink absorbency and strength in the lower layer, so it is necessary to increase the amount of binder in the lower layer. Disaggregation of may become difficult. This is presumably because when the ink jet recording medium is disaggregated, water does not sufficiently penetrate into the paper due to the binder, and disaggregation becomes insufficient. In particular, when disassembling the ink jet recording medium as a broke in a paper factory, if it is processed in the same way as newsprint or printing paper, there is a problem that undisaggregated pieces are mixed into the product when disaggregation is insufficient. End up. For this reason, troubles such as spotted foreign matters are observed on the paper product, or coloring occurs due to the reaction between the ink components and the components in the unseparated pieces when offset printing is performed.

  Accordingly, an object of the present invention is to provide a method that can be easily disaggregated even in a multilayered inkjet recording paper that is difficult to disaggregate by a normal disaggregation method and can be recycled as waste paper pulp.

  In order to solve the above problems, the invention according to claim 1 is an ink jet recording in which at least two coating layers formed by coating a coating liquid containing a pigment and a binder are provided on at least one side of a support. The present invention relates to a method for producing used paper pulp, characterized by adding 100 to 1000 ppm of a disaggregation accelerator to the ink jet recording paper using the paper as a raw paper raw material.

In the ink jet recording paper according to claim 2, the binder of the lowermost coating layer contains a water-soluble polymer and a synthetic resin binder in a mass ratio of 1/5 to 3/1, and The coating amount of the lowermost coating layer is 10 g / m ² or more.

  The invention described in claim 3 is characterized in that the disaggregation aid is a sulfated fatty acid ester.

  Invention of Claim 4 is related with the paper characterized by containing the used paper pulp in any one of Claims 1-4.

  The invention according to claim 5 is a method for disaggregating an inkjet recording paper, wherein at least two coating layers formed by coating a coating liquid containing a pigment and a binder are provided on at least one side of a support. Further, the present invention relates to a method for disaggregating an ink jet recording paper, wherein 100 to 1000 ppm of a disaggregation accelerator is added to the ink jet recording paper.

  According to the present invention, an ink jet recording sheet that has been difficult to disaggregate can be disaggregated without generating undisaggregated pieces. Accordingly, it becomes possible to reuse the ink jet recording paper as a raw paper raw material, and it is possible to produce recycled pulp from the ink jet recording paper. Therefore, it is possible to promote recycling and resource saving.

1. Inkjet recording paper Hereinafter, the inkjet recording paper used in the present invention will be described.
<Support>
The support includes at least wood pulp, and further includes fillers and auxiliaries as appropriate. Examples of wood pulp include known chemical pulp, mechanical pulp, and deinked pulp. These various pulps are used alone or in combination as required. For the support, known fillers and auxiliaries such as fillers, sizing agents, paper strength enhancers, yield improvers, pH adjusters, and various dyes can be appropriately selected for internal or external addition.

<Coating layer>
The coating layer is formed by coating a coating liquid containing a pigment and a binder, and two or more layers are provided on at least one surface of the support. Examples of pigments used in the coating layer include synthetic silica, alumina and alumina hydrate (alumina sol, colloidal alumina, pseudoboehmite, etc.), aluminum silicate, magnesium silicate, magnesium carbonate, light calcium carbonate, heavy calcium carbonate, kaolin, and talc. Inorganic pigments such as calcium sulfate, titanium dioxide, zinc oxide, zinc carbonate, calcium silicate, and aluminum hydroxide; organic pigments such as plastic pigment and urea resin.
The binder used in the coating layer is not particularly limited, and starches such as oxidized starch, esterified starch and cold water soluble starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; proteins such as gelatin, casein and soy protein Water-soluble polymer materials such as polyvinyl alcohol and polyvinylpyrrolidone, acrylic resins, styrene-acrylic resins, vinyl acetate resins, vinyl chloride resins, urea resins, urethane resins, alkyd resins, polyester resins, polycarbonate resins, styrene-butadiene latex And various known binders such as synthetic resin binders such as derivatives thereof can be used alone or in combination of two or more.
For the coating layer, pigment dispersant, water retention agent, thickener, antifoaming agent, preservative, coloring agent, water resistance agent, wetting agent, plasticizer, fluorescent dye, UV absorber as necessary , Antioxidants, and known auxiliaries such as cationic polymer electrolytes can be appropriately blended. In view of maintaining the strength of the coating layer, the blending ratio of these auxiliaries is preferably 20% by weight or less of the entire coating layer.
When providing a coating layer, known coating apparatuses such as various blade coaters, air knife coaters, roll coaters, curtain coaters, kiss coaters, bar coaters, gate roll coaters, and gravure coaters can be used.

<Lowest coating layer>
The lowermost coating layer acts as an ink receiving layer. The coating solution for the lowermost coating layer preferably contains, as a binder, a water-soluble polymer substance such as starch as described above and a synthetic resin binder in a mass ratio of 1/5 to 3/1. . Conventionally, if the amount of the binder is increased in order to improve the strength of the coating layer, when the paper is recycled, water does not sufficiently permeate the paper due to the binder, resulting in insufficient disaggregation. There was a fear. By being in this range, the coating layer does not become too hard and the disaggregation property is improved, and when the disaggregation accelerator described later is used, the disaggregation property can be improved while having an excellent coating layer strength. found.
The coating amount of the lowermost coating layer is preferably 10 g / m ² or more.

<The outermost coating layer>
It is preferable that the outermost coating layer is provided by a cast coating method. In this way, the glossiness of the ink jet recording medium can be greatly improved.
When the outermost coating layer is formed by the cast coating method, the pigment contained in the outermost coating layer includes synthetic amorphous silica, colloidal silica, alumina, calcium carbonate, magnesium carbonate, aluminum hydroxide, kaolin. And various known pigments such as calcined kaolin, talc, titanium dioxide, zinc oxide, and various plastic pigments, and at least one of them can be selected and used. Among these pigments, especially porous pigments such as synthetic amorphous silica and alumina not only form a porous layer with excellent ink absorption compared to other pigments, but also compare in the coating layer. It is preferably used because it becomes transparent and improves the color development of ink when recording.
When the outermost coating layer is formed by a cast coating method, the binder contained in the outermost coating layer includes starches such as oxidized starch and esterified starch; carboxymethylcellulose, hydroxyethylcellulose, etc. Cellulose derivatives; Proteins such as gelatin, casein, soybean protein; polyvinyl alcohol, polyvinyl pyrrolidone, acrylic resin, styrene-acrylic resin, vinyl acetate resin, vinyl chloride resin, urea resin, urethane resin, alkyd resin, polyester resin, polycarbonate resin And various known binders such as styrene-butadiene latex and derivatives thereof. In the present invention, these may be used alone or in combination of two or more.

  The blending ratio of the pigment and binder contained in the outermost coating layer can be changed according to the properties, formulation and support, and is appropriately within a range that does not impair the required quality such as ink absorbency. It can be set. In addition, the outermost coating layer may include a pigment dispersant, a water retention agent, a thickening agent, an antifoaming agent, an antiseptic, a colorant, a water resistance agent, a wetting agent, a plasticizer, a fluorescent dye, and an ultraviolet ray as necessary. Known auxiliaries such as an absorbent, an antioxidant, a release agent, a pH adjuster, and a cationic polymer electrolyte can be appropriately added.

As a casting method, a conventionally known casting method can be applied, but it is particularly preferable to use a solidification casting method. When the coagulation cast method is used, the coating layer is gelled and the degree of plasticization is high, so there is less unevenness in gloss and adhesion to the drum compared to the rewet cast method, and a cast layer with an excellent surface feel can be obtained. Can be obtained.
For example, 1) formic acid, acetic acid, citric acid, tartaric acid, lactic acid, hydrochloric acid, sulfuric acid, or carbonic acid and calcium, zinc, magnesium, sodium, potassium, barium, lead, cadmium, or ammonium. And 2) borax, 3) various borates. In the present invention, at least one selected from these can be suitably used.

2. Disaggregation method In the present invention, the above-described ink jet recording paper, water, disaggregation aid, and other chemicals as necessary are added to the disaggregator, and the concentration and temperature are adjusted to disaggregate. This will be specifically described below.
<Disintegration aid>
The disaggregation aid used in the present invention is preferably a sulfated fatty acid ester. The sulfated fatty acid ester refers to the compound represented by Formula 1.

（Ｒは炭素数１〜１０の直鎖飽和または不飽和炭化水素基を表す。Ｒ’は炭素数１〜１０の直鎖飽和または不飽和炭化水素基を表す。また、Ｒ’’は１〜４の飽和炭化水素基を表す。）

(R represents a straight-chain saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms. R ′ represents a straight-chain saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms. 4 represents a saturated hydrocarbon group.)

In general, sulfated fatty acid esters are obtained by sulfating an ester of an unsaturated carboxylic acid such as oleic acid or ricinoleic acid.
Examples of the sulfated fatty acid ester include sulfated methyl oleate, sulfated butyl oleate, sulfated methyl ricinoleate and sulfated butyl ricinoleate.
The amount of the disaggregation aid is preferably in the range of 100 to 1000 ppm with respect to the mass of the ink jet recording paper to be disaggregated. When the amount of the disaggregation aid is less than this range, the effect of the disaggregation aid is difficult to obtain. On the other hand, even if the amount of the disaggregation aid is larger than this range, the effect of the disaggregation accelerator tends to reach its peak. A more preferable amount of the disaggregation aid is 100 to 500 ppm.

Although the reason why the addition of the sulfated fatty acid ester used in the present invention is effective for disaggregation of the ink jet recording paper is not clear, generally the hydrophilic group of the surfactant is located at the center of the hydrophobic group at the end. It is known that the penetrating power is greater at the side. As shown in Formula 1, the sulfated fatty acid ester has a sodium sulfate group, which is a hydrophilic group, in the center of the molecule, so that a sulfate salt of a general higher alcohol (general formula: R-OSO ₃ Na) or Higher alkyl ether sulfates (general formula: R- (EO or PO) n-OSO ₃ Na, where EO = ethylene oxide, PO = propylene oxide) and sulfonates (general formula: R-SO ₃ Na) It is thought that it is easier to penetrate into the ink receiving layer of the ink jet recording paper than the anionic surfactant. In addition, since sulfated fatty acid esters have relatively low foaming properties, it is considered that sulfated fatty acid esters are suitable factors for the present invention because they are easily stirred at high speed during disaggregation to increase mechanical shearing force. .

<Dissolver>
About a disaggregator, well-known things, such as a high concentration pulper and a low concentration pulper, can be used, and it does not restrict | limit in particular. Moreover, you may perform the process by a kneader, a disperser, a refiner etc. as a process after disaggregation.

<Disaggregation concentration>
The concentration is not particularly limited as long as it is in accordance with the disaggregator, but it may be about 15% for the high concentration pulper and about 5% for the low concentration pulper.

<Additives>
Examples of the additive chemical during disaggregation include alkali metal hydroxides such as NaOH and KOH. In addition, chemicals such as a disaggregation aid, a defluorescent agent, an antifoaming agent, and a deinking agent having a structure other than the surfactant and the sulfated fatty acid ester may be used as long as the effects of the present invention are not inhibited.

<Temperature / Time>
The temperature at the time of disaggregation is 20 ° C or higher, preferably 30 ° C or higher. The higher the temperature, the easier the disaggregation solution penetrates into the ink jet recording paper, and the viscosity decreases and the agitation becomes easier. Although an upper limit is not specifically limited, About 70 degrees C or less is suitable. Even if the temperature is higher than 70 ° C., there is little influence on the disaggregation time and the degree of disaggregation, so the effect of heating is small.

<Others>
In the present invention, when the ink jet recording paper is disaggregated, coated offset printing paper such as newspaper paper, coated paper, art paper, and fine coated paper, non-coated offset printing paper such as fine paper, and electrophotographic paper ( Other types of paper such as so-called PPC paper may be mixed.

3. Recycled pulp In the present invention, the above-mentioned ink jet recording paper is disaggregated as a waste paper raw material to be regenerated pulp, and paper can be produced using this pulp. The method for producing paper is not particularly limited, and may be produced using a conventionally known method as appropriate.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Moreover, in each Example, parts and% are parts by weight and% by weight.

<Preparation of inkjet recording paper>
[Preparation of inkjet recording paper]
10 parts of talc, 1.0 part of aluminum sulfate, 0.1 part of synthetic sizing agent, 0.02 part by weight of yield improver for pulp slurry consisting of 100 parts of hardwood bleached kraft pulp (L-BKP) with a beating degree of 285 ml Was added and paper was made with a paper machine. At the time of papermaking, starch was applied to both sides so that the solid content per side was 1.5 g / m ² to obtain a support having a basis weight of 170 g / m ² .
On one side of the support, the following underlayer coating solution is applied by a blade method so that the dry coating amount is 15 g / m ^2, and further dried to form the lowermost coating layer (underlayer). Provided.
Next, on the under layer, the following cast layer coating solution was applied using a roll coater so that the dry coating amount was 12 g / m ^2, and the following was performed while the coating layer was in a wet state. The coagulation liquid was used for coagulation. Next, the coating layer was pressed onto a cast drum heated to 105 ° C. via a press roll, the mirror surface was copied, and dried to produce an ink jet recording paper.

[Under layer coating solution]
100 parts of synthetic amorphous silica (Fine Seal X37, trade name made by Tokuyama) as a pigment, 5 parts of fully saponified polyvinyl alcohol (PVA-117, trade name made by Kuraray Co., Ltd.) as a binder, and ethylene vinyl acetate 25 parts of polymer emulsion (AM-3150, trade name made by Showa Polymer), 5 parts of cationic ink fixing agent (Polyfix 700, trade name of Showa Polymer Co., Ltd.) as an auxiliary agent, and cationic sizing agent ( A polymer having a solid content of 31.5% was prepared by mixing 5 parts of Polymeron 360, a trade name of Arakawa Chemical Industries).

[Cast layer coating solution]
50 parts of colloidal silica (Quarton PL-1: trade name manufactured by Fuso Chemical Co., Ltd.) and 20 parts of gas phase method silica (Aerosil 200: manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m ² / g as a pigment 30 parts of silica (Fine Seal X-80: manufactured by Tokuyama Kogyo Co., Ltd.), 10 parts of polyvinyl alcohol having a polymerization degree of 2400 (PVA624: trade name, manufactured by Kuraray Co., Ltd.) as a binder, and further defoaming A cast layer coating solution having a concentration of 20% was prepared by blending 0.2 part of the agent.

[Coagulation liquid]
2% borax, 2% boric acid (mass ratio of borax / boric acid = 1/1, calculated in terms of Na ₂ B ₄ O ₇ and H ₃ BO ₃ ), and release agent (FL-48C: Toho Chemical Industry Co., Ltd.) (Product made) 0.2% was mixed and the coagulation liquid was adjusted.

<Disassembly of inkjet recording paper>
[Example 1]
10 g of the ink-jet recording paper previously produced in a TAPPI standard disaggregator was taken as used paper, and 2 L of water was added. To this, a sulfated fatty acid ester (trade name: Sintor ZS, manufactured by Nissin Chemical Laboratory) with a weight of 500 ppm for waste paper was added. Further, 1% by weight of sodium hydroxide was added to the waste paper, and the pulp slurry of Example 1 was obtained by 48 separations at 50 ° C. and 1000 rotations with a TAPPI standard disintegrator. Next, using this slurry, a hand-made sheet having a basis weight of 60 g / m ² was prepared in accordance with JIS P 8222, and then calendered to prepare a sheet for evaluation of disintegration having a smoothness of 200 seconds.

[Example 2]
An evaluation sheet of Example 2 was obtained in the same manner as in Example 1 except that the amount of the sulfated fatty acid ester was 100 ppm with respect to used paper.

[Example 3]
An evaluation sheet of Example 3 was obtained in the same manner as in Example 1 except that the disaggregation temperature was 65 ° C.

[Example 4]
An evaluation sheet of Example 4 was obtained in the same manner as in Example 1 except that the amount of sulfated fatty acid ester was 1000 ppm with respect to used paper.

[Comparative Example 1]
A sheet for evaluation of Comparative Example 1 was prepared in the same manner as in Example 1 except that the sulfated fatty acid ester was not added.

[Comparative Example 2]
An evaluation sheet of Comparative Example 2 was produced in the same manner as Comparative Example 1 except that the disaggregation temperature was 65 ° C.

[Comparative Example 3]
A sheet for evaluation of Comparative Example 3 was prepared in the same manner as in Example 1 except that 75 ppm of sulfated fatty acid ester was added.

[Comparative Example 4]
Evaluation of Comparative Example 4 in the same manner as in Example 1 except that 500 ppm of ethylene oxide adduct of higher alcohol (trade name: Emulgen 707, manufactured by Kao) was added instead of using 500 ppm of sulfated fatty acid ester. A sheet was obtained.

[Comparative Example 5]
Evaluation of Comparative Example 5 in the same manner as in Example 1 except that 1000 ppm of ethylene oxide adduct of higher alcohol (trade name: Emulgen 707, manufactured by Kao) was added instead of using 500 ppm of sulfated fatty acid ester. A sheet was obtained.

[Comparative Example 6]
Example 1 except that 500 ppm of an ethylene oxide / propylene oxide adduct of higher alcohol (trade name: Neutron T-15, manufactured by Nisshin Chemical Laboratory) was used instead of using 500 ppm of the sulfated fatty acid ester for used paper. Similarly, an evaluation sheet of Comparative Example 6 was obtained.

[Comparative Example 7]
A sheet for evaluation of Comparative Example 7 in the same manner as in Example 1 except that 500 ppm of sodium alkylnaphthalene sulfonate (trade name: Perex NB-L, manufactured by Kao) was used instead of using 500 ppm of sulfated fatty acid ester. Got.

[Comparative Example 8]
Instead of using 500 ppm of sulfated fatty acid ester for used paper, sodium alkylnaphthalene sulfonate (trade name: Perex NB-L, manufactured by Kao Corporation) was used at 1000 ppm. It was.

<Evaluation of disaggregation method>
Evaluation of the disaggregation method was performed by visually evaluating the number of undisaggregated pieces in the produced handsheet. That is, the number of unseparated pieces visually observed in an area of 10 cm × 10 cm in the handsheet was counted and evaluated according to the following criteria. The results are shown in Table 1.

○: The number of unseparated pieces is less than 3 △: The number of unseparated pieces is 3 or more and less than 5 ×: The number of unseparated pieces is 5 or more and less than 10 xx: Unseparated The number of pieces is 10 or more

  As is apparent from Table 1, in Examples 1 to 4 using the sulfated fatty acid ester of the present invention, a relatively good disaggregation result was obtained, but no sulfated fatty acid ester was added or added. In Comparative Examples 1 to 3 in which the amount is insufficient, many undissolved pieces remain after disaggregation. Moreover, even in Examples 4 to 8 using a general alcohol-based surfactant or sodium sulfonate, there are problems such as a large amount of undisaggregated pieces or a large amount of foaming that cannot be disaggregated.

Claims (5)

  An ink jet recording paper provided with at least two or more coating layers formed by applying a coating liquid containing a pigment and a binder on at least one side of a support is used as a waste paper raw material, and is 100 to A method for producing waste paper pulp, comprising adding 1000 ppm of a disaggregation accelerator to make a pulp. In the inkjet recording paper, the binder of the lowermost coating layer contains the water-soluble polymer and the synthetic resin binder in a mass ratio of 1/5 to 3/1, and the coating of the lowermost coating layer is applied. The method for producing waste paper pulp according to claim 1, wherein a work amount is 10 g / m ² or more.   The method for producing waste paper pulp according to claim 1 or 2, wherein the disaggregation aid is a sulfated fatty acid ester.   Paper containing the waste paper pulp according to any one of claims 1 to 4.   A method for disaggregating an inkjet recording paper, wherein at least two coating layers formed by coating a coating liquid containing a pigment and a binder on at least one side of a support are provided, A method for disaggregating ink jet recording paper, comprising adding 100 to 1000 ppm of a disaggregation accelerator.