JP2010019910A - Electrophotographic paper and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electrophotographic paper suppressed in the occurrence of curling while it contains a high percentage of used paper pulp. <P>SOLUTION: This electrophotographic paper is obtained by paper-making a paper-making raw material containing 70 mass% or more used paper pulp, and its ash content (based on Japanese Industrial Standards P 8251) is 6% or more. A cationic coagulant, a sizing agent and a cationic flocculant are added in this order to the paper-making raw material, and the charge density of disaggregated pulp slurry filtrate obtained by disaggregating the obtained electrophotographic paper based on JIS P 8220 is 0.7-1.4 Meq/g, and Steckigt sizing (based on JIS P 8122) is 0.10-0.35 sec/(g/m<SP>2</SP>). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic paper and a manufacturing method thereof.

  From the viewpoint of effective utilization of resources in recent years, waste paper pulp is highly formulated in electrophotographic applications. Waste paper pulp is added with a deinking agent containing a surfactant in order to remove ink in the production process, has high hydrophilicity (usually a hydrate size of about 8 seconds), and has a high equilibrium moisture content. It has characteristics. Accordingly, when an electrophotographic paper having a high content of waste paper pulp is used in an electrophotographic printing machine, there is a problem that a difference in moisture content occurs between the front surface and the back surface of the paper, and the paper tends to curl.

  As a means for solving the problem of the difference in moisture content, in an electrophotographic paper having a high content of used paper pulp, the addition of an internal sizing agent and an external sizing agent is assumed as a solution. However, when the ratio of the used paper pulp is less than 70%, the effect of adding the internal sizing agent and the external additive sizing agent can be seen. However, when the ratio of the used paper pulp is 70% or more, the internal sizing agent is used. However, there is a limit in correcting the difference in moisture content only by adding externally added sizing agents.

  As described above, according to the knowledge of the present inventors, when used paper pulp is used in an amount of 70% by mass or more of the papermaking raw material, the curl at the time of moisture absorption is compared with the electrophotographic paper in which the mixing ratio of the used paper pulp is less than 70% by mass. The problem that becomes large occurs. The curling problem at the time of moisture absorption in 70% by weight or more of waste paper pulp is different depending on the type of waste paper, but it is difficult to make the type of waste paper used as a raw material constant. Because the expansion and contraction rate and equilibrium moisture of the waste paper pulp material obtained with fluctuations vary, in order to use a wider range of waste paper as a raw material, even if these characteristics fluctuate, the amount of curl change should be kept constant. There is a need to develop electrophotographic paper that can be suitably used as photographic paper.

  Further, for example, Patent Document 1 has the same electrophotographic aptitude as high-quality paper-grade electrophotographic paper made of conventional virgin chemical pulp, and after copying is equivalent to conventional electrophotographic paper immediately after opening and after moisture absorption. An electrophotographic transfer paper having curling properties has been proposed. This paper contains 70% or more of waste paper pulp in the total pulp, and the moisture content at the time of opening the package matches a predetermined formula. However, this document does not disclose the idea of controlling curl by controlling the sizing agent.

  Further, Patent Document 2 discloses a plain paper made of at least pulp as a recording paper with less curl, containing an organic acid having three or more carboxyl groups in the molecule, and a CD expansion / contraction of the paper. A recording sheet characterized in that the rate (%) is in the range of 0.25 to 0.65% has been proposed. However, the same document does not disclose or suggest curl control in the case where wastepaper pulp is highly blended.

  Further, Patent Document 3 discloses an electrophotographic transfer paper that can reduce curling after thermal fixing of a toner image in an electrophotographic system and has high suitability for double-sided printing, and an image of an electrophotographic recording system using the same. A recording method has been proposed. The sheet is characterized in that the ratio of the front-back difference of the elongation at break to the elongation at break of all layers is in the range of −10 to 10% in both the MD direction and the CD direction. However, even in this document, there is no disclosure or suggestion of curl control when wastepaper pulp is highly blended.

Furthermore, in Patent Document 4, even when multiple newspaper newspapers and magazine waste papers are blended, curlability, runnability, and appearance quality can be improved to increase the image quality and speed of recent electrophotographic copying machines and printers. An electrophotographic transfer paper that can satisfy the requirements has been proposed. This paper contains 50 to 100% by weight of waste paper pulp mainly composed of at least one of waste newspaper and magazine waste paper, has an ISO whiteness of 75 to 95%, and a moisture stretching ratio of 0.6%. In the following, the critical length in the cross direction (CD direction) measured by the Clark stiffness test method is set to 15 cm or more. However, the paper according to this document has a high content of used paper, but no solution for curling has been shown.
Japanese Patent Laid-Open No. 06-295087 JP 2006-77356 A JP 2007-121409 A JP 2007-298620 A

  The main problem to be solved by the present invention is to provide an electrophotographic paper in which curling is suppressed and a method for producing the same while the waste paper pulp is highly blended.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
An electrophotographic paper having an ash content (in accordance with JIS P 8251) of 6% or more obtained by papermaking a papermaking raw material containing 70% by weight or more of waste paper pulp,
In the papermaking raw material, a cationic coagulant, a sizing agent, and a cationic flocculant are added in this order,
The charge density of the disaggregated pulp slurry filtrate obtained by disaggregating the obtained electrophotographic paper according to JIS P 8220 is 0.7 to 1.4 Meq / g,
The rigid size (according to JIS P 8122) is 0.10 to 0.35 sec / (g / m ² ).
An electrophotographic paper characterized by that.

[Invention of Claim 2]
The waste paper pulp is composed mainly of newspaper waste paper and / or magazine waste paper, and the composition ratio of the disaggregated pulp slurry is NKP: 10-20, LKP: 50-70, MP: 10-40,
The cationic coagulant is added in the raw material pulp blending adjustment stage,
The sizing agent is a neutral rosin sizing agent and is added in a later step different from the cationic coagulant,
The electrophotographic paper according to claim 1.

ただし、Ｐはエポキシ基又はハロヒドリン基、ｐは０〜２０の整数であり、Ｒ１〜Ｒ４は、水素、炭素数１〜３のアルキル基、ヒドロキシアルキル基、又は、ベンジル基であり、Ｘ１〜Ｘ２は陰イオンである。

ただし、ｐは０〜２０の整数であり、Ｒ１〜Ｒ４は、水素、炭素数１〜３のアルキル基、ヒドロキシアルキル基、又は、ベンジル基であり、Ｘ１〜Ｘ２は陰イオンである。 [Invention of Claim 3]
The cationic coagulant is
One or more amines selected from ammonia, primary amines, secondary amines, and tertiary amines;
A polycationic substance mainly comprising a compound represented by the following formula (1);
A polyalkyleneimine-modified product having a structural unit represented by the following formula (2) obtained by reacting a polyalkyleneimine having a molecular weight of 10,000 to 70,000,
In the blending adjustment stage of the raw material pulp, 1.0 to 3.0 kg / pulpton is added as a solid content,
The electrophotographic paper according to claim 1 or 2.

However, P is an epoxy group or a halohydrin group, p is an integer of 0 to 20, R1 to R4 are hydrogen, an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group, or a benzyl group, and X1 to X2 Is an anion.

However, p is an integer of 0-20, R1-R4 is hydrogen, a C1-C3 alkyl group, a hydroxyalkyl group, or a benzyl group, and X1-X2 is an anion.

[Invention of Claim 4]
The polyalkyleneimine is polyethyleneimine;
The electrophotographic paper according to claim 3.

[Invention of Claim 5]
The electrophotographic paper according to any one of claims 1 to 4, wherein the cationic coagulant, the sizing agent, and the cationic flocculant are added at the following locations and in the following addition amounts. .
The cationic coagulant is added in an amount of 1.0 to 3.0 kg / pulpton as a solid content in the raw material pulp blending adjustment stage.
The sizing agent is added in a solid content of 3.0 to 8.0 kg / pulpton in a seed box.
The cationic flocculant is added in an amount of 0.1 to 5.0 kg / pulpton as a solid content in a subsequent step after the sizing agent is added.

[Invention of Claim 6]
A method for producing an electrophotographic paper having a ash content (conforming to JIS P 8251) of 6% or more by papermaking a papermaking raw material containing 70% by mass or more of waste paper pulp,
To the papermaking raw material, a cationic coagulant, a sizing agent, and a cationic flocculant are added in this order,
The charge density of the disaggregated pulp slurry filtrate obtained by disaggregating the obtained electrophotographic paper according to JIS P 8220 is 0.7 to 1.4 Meq / g, and the hydrate size (according to JIS P 8122) is 0. 10 to 0.35 seconds / (g / m ² )
An electrophotographic paper manufacturing method characterized by the above.

  According to the present invention, an electrophotographic paper in which the occurrence of curling is suppressed while wastepaper pulp is highly blended and a method for producing the same are provided.

Next, an embodiment of the present invention will be described.
The present inventors have added an internal sizing agent, and when the ratio of the used paper pulp exceeds 70%, the ionicity in the raw slurry is anionic due to the anionic trash derived from the used paper pulp. Not only inhibits the fixing of the internally added sizing agent to the pulp fiber, but also the phenomenon that the effect of the externally added size does not increase because the internally added size is not fixed, and the present invention is completed. It came to.

  The electrophotographic paper of this embodiment is a paper having an ash content (conforming to JIS P 8251) of 6% or more obtained by making a papermaking raw material containing 70% by mass or more of waste paper pulp.

  As mentioned above, it is difficult to make the type of waste paper used as a raw material constant, and there is a problem that the expansion rate and equilibrium moisture of the used paper pulp raw material obtained as the waste paper varieties vary. In addition, due to changes in used paper varieties, ionic fluctuations in the obtained used paper pulp raw material itself also cause a decrease in size.

  The present inventor preferably uses waste newspaper made of newspaper with high recovery rate as raw material pulp, and blends more than 70% of waste paper pulp made of newspaper waste and / or magazine waste paper. However, since the raw material pulp types constituting newspapers and magazine papers in various paper manufacturers can be approximated, fluctuations in the raw material composition due to the constituent pulp types can be suppressed, and the types of fillers contained are also similar. From this, it is also found that it is most suitable.

  Newspaper paper, in particular, generally contains 50% or more of waste paper pulp, has a low content of virgin mechanical pulp and kraft pulp, and even if various types of virgin pulp are used, paper is made once. Since the waste paper is pulped by the waste paper treatment, its properties are homogenized, and it has an advantage of almost constant properties similar to the use of a so-called same kind of pulp raw material.

  The ash content of the electrophotographic paper in this embodiment is mainly composed of waste paper-derived ash, and is added as necessary, but preferably contains calcium carbonate and / or white carbon as its main component. It is preferable that the used paper pulp is selected and combined to adjust the ash content of the used paper to obtain an electrophotographic paper.

  Furthermore, the inventor of the present invention frequently uses white carbon as an opacity improver for newsprint paper and / or magazine paper, and in recent years, with the neutral papermaking of newsprint paper and / or magazine paper, calcium carbonate is used as a filler. Focusing on the fact that it is frequently used, it has been found that waste paper pulp derived from newsprint and / or magazine paper can be suitably used.

  Although most of the ash derived from used paper is discharged out of the system in the process of recycling used paper pulp from used paper, fine ash components that are physically or chemically fixed to the fiber remain in the used paper pulp, and again the papermaking raw material As compared with virgin filler, it has a high adhesiveness to the raw material pulp, and therefore has a synergistic effect of improving toner fixability when electrophotographic printing is performed.

  The used paper pulp derived from newspaper and / or magazine paper has the characteristics that fine inorganic particles such as white carbon and calcium carbonate remain and are contained in the used paper pulp as fine filler derived from used paper.

  In the present invention, the ash content (according to JIS P 8251) is preferably 6% or more, preferably 6 to 12% by mass, more preferably 7 to 10%, including the filler derived from newspaper and / or old magazine paper. It is preferable to adjust so that it may become mass%.

  White carbon contained in waste paper pulp derived from newsprint and / or magazine paper can improve toner transfer and heat fixability in electrophotographic printing. Is porous because it forms a secondary particle aggregate in which fine primary particles are aggregated, so that the toner tends to adhere to the surface, and the electrophotographic printing surface is less likely to become smudged due to unfixed toner. Even when printing is performed by a non-impact printer system using an electrophotographic printing machine, white carbon absorbs silicone oil, so there is no possibility that toner fixing is hindered by silicone oil.

  In addition, calcium carbonate is a sizing agent that can be suitably used in the present invention, although it has a relatively low residual ratio as other fillers derived from newspaper and / or magazine waste paper, such as fillers derived from waste paper than the above-mentioned white carbon. Good compatibility, especially contributes to improving the chemical yield of neutral rosin sizing agent, makes it easy to demonstrate size, and calcium carbonate has high surface resistance, high background (paper attached to the photoconductor in the transfer process) When the filler in the powder is mixed into the developer in the developing part, when the toner and the filler are of opposite polarity, an aggregate is formed, and this aggregate is developed in the non-image area), and the release (of the photoreceptor) The occurrence of a phenomenon called “a normal electrostatic latent image cannot be obtained due to a decrease in electrical resistance in a dark place” can be solved at the same time.

  The residual fine filler derived from these waste papers has a volume average particle diameter of 0.01 to 30 μm, preferably 1 to 20 μm.

  On the other hand, in order to reduce the ash content (conforming to JIS P 8251) to less than 6%, it is necessary to sufficiently wash the fine fibers and ash derived from waste paper at the raw material adjustment stage, and a great amount of washing equipment is required.

  On the other hand, when it exceeds 12%, when used in an electrophotographic printing machine, the heat dissipation of the paper is deteriorated, and the paper becomes easy to accumulate heat and curl easily. Therefore, the obtained electrophotographic paper is adjusted so that the ash content measured according to JIS P 8251 is 6 mass% or more, preferably 6 to 12 mass%, more preferably 7 to 10 mass%.

  Waste paper pulp used in this embodiment is preferably newspaper waste paper and / or magazine waste paper consisting of newsprint paper and / or magazine paper, as well as cuts, waste paper, width generated in bookbinding, printing factories, cutting offices, etc. Unprinted waste paper such as upper white, special white, medium white, white loss, etc., which has been dropped is disassembled from old paper pulp, fine paper, high quality coated paper, medium quality paper, medium quality coated paper, reprint, etc. , Intaglio printing, electrophotographic method, thermal method, thermal transfer method, pressure-sensitive recording method, ink jet recording method, waste paper printed with carbon paper, etc. and waste paper written with water-based, oil-based ink, pencil etc. Black ink, pulp regenerated so as to be reusable (hereinafter abbreviated as DIP), and the like can be used.

  In addition to the above waste paper, virgin chemical pulp (hardwood bleached kraft pulp, softwood bleached kraft pulp, hardwood unbleached kraft pulp, softwood unbleached kraft pulp, hardwood bleached sulfite pulp) , Pulp made by chemically treating wood and other fiber raw materials, such as softwood bleached sulfite pulp, hardwood unbleached sulfite pulp, softwood unbleached sulfite pulp, etc.) and ground pulp that mechanically pulped wood or chips Virgin, such as semi-chemical pulp that has been soaked with chemicals after being soaked in wood or chips and then mechanically pulped, chemimechanical pulp, and chips are digested until slightly softened and then refined by refiner Pulp may be included.

  The composition of the raw pulp in the present invention is NKP: 10-20, LKP: 50-70, MP: 10-40 in the disaggregated pulp slurry obtained by disaggregating the obtained electrophotographic paper according to JIS P 8220. It is preferable that they are blended as described above. NKP (conifer kraft pulp) is necessary to supplement the paper strength reduction caused by blending 70% by weight or more of waste paper pulp in the electrophotographic paper produced in the present invention. Due to heat fixing in the machine, the paper becomes brittle, and there arises a problem that it is easily broken during holding by a metal fitting during use or filing. On the other hand, if NKP exceeds 20%, the texture of the electrophotographic paper is lowered and the appearance is deteriorated, and the toner fixing property is lowered and the printability is lowered.

  LKP (hardwood kraft pulp) is necessary for the purpose of maintaining the flatness of the electrophotographic paper surface and the toner fixing property in the present invention. When LKP is less than 50%, the toner fixing property is lowered and the printability is inferior. If it exceeds 70%, it is also due to the fact that it is originally a short fiber, so that the rate of curling increases and paper dust tends to be generated.

  MP (mechanical pulp) has an effect of complementing the decrease in bulk caused by blending 70% by weight or more of waste paper pulp in the electrophotographic paper produced in the present invention. If the MP is less than 10%, the electrophotographic paper does not become bulky and has no waist, so curling is difficult to occur, but there is a problem that transportability and workability are poor. If the MP exceeds 40%, it is a pulp that has a low strength improvement effect from the beginning, and contains a large amount of resin, and the pulp fiber itself is brittle, so that there is a problem that it is easily broken during holding and filing during use. .

  The adjustment of these raw pulps is usually difficult when blending 70% by weight or more of waste paper pulp derived from waste paper, but the waste paper recycling promotion center is mainly made up of used newsprint paper and magazine waste paper, which is almost the same in paper manufacturing companies. It can be adjusted by using sorted waste paper that conforms to waste paper classification.

  However, in the case of containing virgin chemical pulp or mechanical pulp other than the above waste paper, the content is less than 30% by weight. If it exceeds 30% by weight, the degree of reduction of the sizing effect by the anion trash derived from waste paper, which is a problem of the present invention, is small, and the effects of the present invention cannot be fully exhibited.

A cationic coagulant, a sizing agent, and a cationic flocculant are added in this order to the papermaking raw material of this embodiment, and the obtained electrophotographic paper is disaggregated according to JIS P 8220, and the disaggregated pulp slurry filtrate Has a charge density of 0.7 to 1.4 Meq / g, and a hydrate size (based on JIS P 8122) of 0.10 to 0.35 / (g / m ² ).

  When the raw material pulp contains 70% or more of the used paper pulp, the ionic variation in the raw material pulp is large due to the anionic trash derived from the used paper. The effect of the chemicals in the process is not stable, the size is reduced, the operation is not stable due to the addition of excess chemicals and the drainage at the wet end, etc., and the quality fluctuation increases, resulting in the solution of the present invention. The problem of curling, which is a problem, appears, and an electrophotographic paper having good quality cannot be obtained.

  Therefore, as shown in FIG. 1, the cationic coagulant X1 is solidified in the blending adjustment stage (from receiving chest 1 to machine chest 3) of the raw material pulp constituting the electrophotographic paper according to this embodiment, preferably in blending chest 2. After adding 1.0 to 3.0 kg / pulp ton per minute to stabilize the ionicity of the raw material pulp, the sizing agent X2 is added in the subsequent step, preferably the seed box 4.

  By adding the cationic coagulant X1 in the compounding chest, it becomes possible to suppress anionic trash that causes the curling problem that is the subject of the present invention, and to easily adjust the ionicity in the subsequent process, thereby causing a curling problem. To solve the problem.

  Here, in the compounding chest 2, the raw material pulp is supplied via the double thickener 12 from one or two or more receiving chests 1 that have received various raw material pulps, and the various raw material pulps are mixed. The mixed raw pulp is sent to the seed box 4 through the machine chest 3.

  As the cationic coagulant, those commercially available can be used. For example, cationic polyacrylamide, polydiallyldimethylammonium chloride, polyethyleneimine, polyamine having a molecular weight of 50000 or more, polyamine modified with ethyleneimine graph, polyetheramide, polyvinylimidazole, polyvinylpyrrolidine, polyvinylimidazoline, polyvinyltetrahydropyrine , Poly (dialkylaminoalkyl vinyl ethers), protonated or quaternized forms of poly (dialkylaminoalkyl (meth) acrylates) and adipic acid and polyalkylene polyamines, acrylamide or methacrylamide and dialkylaminoethyl acrylate or dialkylaminoethyl methacrylate Copolymers such as acrylamide and dimethylaminoethyl acrylate A copolymer of quaternized form using the form or methyl chloride salt with hydrochloric acid and.

  Among them, the cationic coagulant X1 suitably used in this embodiment is one or more amines selected from ammonia, primary amine, secondary amine, and tertiary amine, and the following formula (1): A polyalkyleneimine-modified product having a structural unit represented by the following formula (2) obtained by reacting a polycationic substance mainly composed of a compound represented by a polyalkyleneimine having a molecular weight of 10,000 to 70,000, and a raw material pulp In the blending adjustment stage, a solid content of 1.0 to 3.0 kg / pulpton, preferably 1.5 to 2.5 kg / pulpton is added.

  If it is less than 1.0 kg / pulpton, sufficient anion trash coagulation and ionic neutralization effects are not observed, and the effect of adding a sizing agent in the subsequent process is difficult to occur, resulting in a curl problem.

  If it exceeds 3.0 kg / pulp ton, the ionicity in the raw material pulp system becomes excessively cationic, resulting in unevenness in unnecessary condensation and size effect, and even excessive addition causes curling problems and poor texture. Problems arise.

  However, P is an epoxy group or a halohydrin group, p is an integer of 0 to 20, R1 to R4 are hydrogen, an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group, or a benzyl group, and X1 to X2 Is an anion.

  However, p is an integer of 0-20, R1-R4 is hydrogen, a C1-C3 alkyl group, a hydroxyalkyl group, or a benzyl group, and X1-X2 is an anion.

Furthermore, it is preferable that the polyalkyleneimine is polyethyleneimine. Polyethyleneimine has, for example, a molecular weight of 2 × 10 ⁶ or less, preferably 2000 to 1000000. Particular preference is given to using polyethyleneimines having a molecular weight of 5000 to 800,000. As a commercially available coagulant corresponding to this embodiment, SC-924 manufactured by Hymo Corporation is exemplified as a suitable cationic coagulant, and a more preferable cationic coagulant has a charge density of 18 Meq / g or more, More preferably, it is 18-20 Meq / g.

  The addition of the cationic coagulant X1 in the present invention is preferably performed in the blending adjustment stage of the raw material pulp, and more preferably in the blending chest 2. The raw pulp in the blending adjustment stage is blended with anionic trash generated in the manufacturing process of various different raw pulps, as well as disaggregated pulp consisting of spoiled paper generated in the papermaking process. In order to stabilize the ionicity in the subsequent process, the cationic coagulant X1 exhibiting a high charge density may be added at the raw material pulp blending adjustment stage in order to stabilize the ionicity. It has been found that it is most suitable for fixing the sizing agent X2 added in the post-process.

  The sizing agent X2 in the present invention can be added in any papermaking process after the raw material pulp blending adjustment stage, but is most preferably added in the seed box 4.

  By adding the sizing agent X2 in the seed box 4, uniform mixing with the raw material pulp is promoted, and uniform sizing properties can be obtained.

  Internally added sizing agents that can be used in this embodiment comprising a raw pulp composition containing 70% or more of waste paper pulp derived from waste paper are rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, neutral sizing agents, etc. Can be suitably used in combination with a fixing agent of an appropriate sizing agent and fiber, such as sulfate band, cationized starch, etc., but has been conventionally used as a sizing agent for neutral papermaking. When AKD or ASA is used, the surface energy of the paper is lowered when the amount of the sizing agent is increased for the purpose of increasing the sizing degree, and the fixability of the toner transferred by the electrophotographic copying machine tends to deteriorate. In addition, there is a tendency that paper feeding cannot be performed at the paper feeding portion of the copying machine or that a paper feeding trouble such as feeding a plurality of papers at a time increases.

  In this embodiment, a neutral sizing agent, particularly a neutral rosin sizing agent, is preferably used from the viewpoints of runnability in an electrophotographic copying machine, printer, and the like and paper storage stability after copying. When a neutral rosin sizing agent is used as an internal sizing agent, an anion derived from waste paper is combined with the cationic coagulant X1 added in the raw material blending process in the production of electrophotographic paper with 70% or more waste paper pulp. Electrophotographic transfer paper that can reduce the problem of size reduction due to trash, can effectively secure size, prevent curling, and has excellent toner fixing properties and paper feeding characteristics in copying machines Can be provided.

  The neutral rosin sizing agent in the present embodiment is, for example, a carboxylic acid of a sizing agent in a neutral to alkaline pH range as introduced in pages 31 to 34 of the paper pamphlet magazine 47, No. 5. Rosin is treated with a special hydrophobizing modification to prevent pulp dissociation and salt formation with Ca ions, and is effective as a sizing agent, and various surfactants or water-soluble polymers. It is an emulsion type rosin sizing agent obtained by emulsification.

  Here, the rosin substances include gum rosin, wood rosin, tall oil rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, aldehyde-modified rosin, rosin ester, and other rosins, and further rosins and acrylic acid, maleic anhydride. Examples of the heat reaction product with α, β-unsaturated carboxylic acid such as acid, fumaric acid, itaconic acid, etc., but insolubilization treatment such as polymerization and water resistance are performed for the purpose of suppressing elution of rosin substance in the neutral region. be able to.

  The ionicity of the neutral rosin sizing agent can be selected from anionic and cationic depending on various surfactants or water-soluble polymers used during emulsification.

  In the case of a neutral rosin sizing agent, the expression of size varies depending on the composition ratio of the hydrophobically modified rosin, the reinforced rosin, and the unmodified rosin in the sizing agent. According to the knowledge of the present inventors, the addition amount of the neutral rosin sizing agent is 3.0 to 8.0 kg / pulpton, more preferably 3.5 to 7.5 kg / pulpton in solid content.

  If it is less than 3.0 kg / pulp ton of pulp, even if a surface sizing agent is applied as described later, sufficient paper size cannot be exhibited as a whole paper. On the other hand, when the amount of the neutral rosin sizing agent added is 8.0 kg / pulp ton or more of pulp, the sizing property also reaches a saturated state, and stains occur in each part of the paper machine during operation. Further, when the electrophotographic transfer paper in this embodiment is produced, the use of a neutral rosin sizing agent requires the combined use of a sulfuric acid band from the viewpoint of size and operability. The addition amount of the sulfuric acid band varies depending on the papermaking pH at the time of papermaking, but is preferably in the range of 3.0 to 8.0 kg / pulpton mass% with respect to pulp.

  As a fixing agent for a sizing agent such as a neutral rosin sizing agent, an Al polyvalent metal compound (for example, sulfuric acid band, polyaluminum chloride, polyaluminum silicate sulfate, sodium aluminate, etc.) can be used. When fine fibers and ash are present in the pulp, it reacts with a sulfuric acid band and the like, and the conventional size fixing effect is not exhibited. Therefore, a cationic flocculant is added from the viewpoint of sequestering strong anionic fine fibers and ash with the cationic coagulant X1.

  In the present invention, the sizing agent X2 is preferably added in the seed box 4 in the subsequent step of the cationic coagulant X1, particularly immediately before the head box 9, so that the waste paper pulp fiber having a particularly high anionic property is used. The anionic neutral rosin sizing agent is fixed through the above polyvalent metal compound of Al (for example, sulfate band, polyaluminum chloride, polyaluminum silicate sulfate, sodium aluminate, etc.), and further the cationic flocculant X3 It is presumed that the effect of collecting the sizing agent fixed on the fine fibers, the free sizing agent, and the like is exhibited by the addition of sizing, and the sizing property is expressed by reacting with aluminum ions on the dryer.

  Further, in the present invention, as a characteristic of the neutral rosin sizing agent, the blending amount in the paper increases and the friction coefficient of the paper increases, so that the size improvement that becomes a problem when using AKD is increased. As a result, the so-called multi-feed problem in which a plurality of transfer sheets are fed on the copying machine is solved. Furthermore, by performing neutral papermaking in the present invention, since calcium carbonate can be blended as a filler, the friction coefficient of the paper and the remarkable improvement in controllability, as well as the high background and the release, which were conventionally contradictory properties, and The so-called phenomenon problem can be solved at the same time.

  As the cationic flocculant X3 after addition of the sizing agent preferably used in this embodiment, a cationic flocculant having a lower charge density than the cationic flocculant X1 used in the previous raw material blending step is used.

  Addition of cationic coagulant X1 and coagulation of anionic trash to add sizing agent X2 and further cationic flocculating agent X3 promotes fixing of the sizing agent to pulp fibers. At the same time, the agglomerated anionic trash aggregates to form flocs, so that the factor that inhibits the fixing of the sizing agent to the pulp fiber is reduced. Under such a mechanism, the anionic trash present in the slurry can be further adsorbed to the pulp, and the process can be passed along with the paper stock in a minimal state, thereby reducing paper dust and powder omission caused by the anionic trash. it can. As a result, dirt, defects and paper breaks can be reduced, and productivity can be improved.

  The cationic flocculant X3 after the addition of the sizing agent X2 is a post-process after the addition of the sizing agent X2, in the illustrated example, immediately before the second fan pump 8 through the first fan pump 5 and the screens 6 and 7, with a molecular weight of 300. 10 to 20 million, preferably 5 to 20 million, and the cationic monomer has a mol% of 5 to 100 mol%, preferably 10 to 100 mol%, preferably 10 to 100 mol%. The coalescence is added in a solid content of 0.1 to 5.0 kg / pulpton, more preferably 0.5 to 4.0 kg / pulpton. Specific examples include a cationic polyamine resin, a cationic polyamine polyamide resin, a cationic polyacrylamide, a cation-modified starch, a styrene acrylic resin, and a cationic thermosetting resin.

  If the molecular weight of the cationic water-soluble polymer or copolymer is less than 3 million, the effect is not sufficient, and if it exceeds 20 million, the effect is small and the cost is high.

  When the cationic flocculant X3 is added to the raw material pulp after the addition of the sizing agent X2, the size property can be improved, and as a result, the curl that is the subject of the present invention can be improved.

  The cationic flocculant X3 is added immediately before supplying the papermaking raw material to the papermaking net, ie, immediately before the so-called head box 9, after the cationic coagulant X 1, particularly immediately before the head box 9. By adding the sizing agent X2, a polyvalent metal compound of Al (for example, sulfuric acid band, polyaluminum chloride, polyaluminum silicate sulfate, sodium aluminate, etc.) on the waste paper pulp fiber having a particularly high anionic property. The anionic neutral rosin sizing agent is fixed through the slag, and the addition of the cationic flocculant X3 expresses the effect of collecting the sizing agent fixed on the fine fibers and the free sizing agent on the dryer. Therefore, it is presumed that size characteristics are expressed by reacting with aluminum ions.

  In addition, the amount of fine filler (white carbon or calcium carbonate) that is lost in the papermaking net can be significantly reduced.

  Here, in this invention, the addition amount of the cationic flocculant X3 shall be 50-400 ppm with a pure part. Preferably, it is set to 100 to 100 ppm. If it is less than 50 ppm, it is difficult to obtain the effect of improving the yield of calcium carbonate. Moreover, when it exceeds 400 ppm, the texture will deteriorate.

  In this embodiment, when the cationic coagulant X1 is added at the raw material pulp blending adjustment stage, and the sizing agent X2 is a neutral rosin sizing agent and added in a post-process different from the cationic coagulant X1, It becomes more preferable. That is, fine fibers and ash having strong anionic properties are stabilized beforehand with the cationic chest X1 in the compounding chest 2, etc., and the sizing agent X2 and the size fixing agent are added in the seed box 4 etc. in the subsequent process. It is preferable to block with the flocculant X3.

  In the electrophotographic paper obtained in the present invention, the charge density of the disaggregated pulp slurry filtrate disaggregated according to JIS P 8220 is 0.7 to 1.4 Meq / g.

  The charge density of the disaggregated pulp slurry filtrate of the electrophotographic paper according to the present invention, disaggregated according to JIS P 8220, is a cationic coagulant X1, a sizing agent X2, Although the cationic flocculant X3 can be used as the adjustment main agent, the cationic coagulant X1 added in the raw material pulp blending adjustment stage is mainly intended to stabilize the ionicity of the raw material pulp slurry. Is largely dependent on the addition amount of the cationic flocculant X3 added immediately before the papermaking raw material is supplied to the papermaking net, that is, immediately before the so-called head box 9.

The present inventors have intensively studied on the production of electrophotographic paper containing 70% or more of waste paper pulp, and even if a large amount of anionic trash derived from waste paper pulp is included in the raw material pulp blending stage, the charge density is preferably 18 Meq. / G or more cationic coagulant X1 is added to promote the aggregation of so-called anionic trash, anionic substances such as fine fibers, and further control the charge density to +0.001 to +0.015 meq / L, Further, the internal sizing agent X2 is added in the subsequent process, and further, the coagulant X3 having a lower charge density (strength) than the coagulant X1 added in the raw material adjustment process is added, and the fixing of the sizing agent X2 is promoted and remains. Generation of defects due to anion trash, etc. can be suppressed, and the obtained electrophotographic paper is disaggregated according to JIS P 8220. Charge density of the filtrate was 0.7~1.4Meq / g, nice hydrin size (according to JIS P 8122) is characterized by a 0.10 to 0.35 seconds / (g / m ²⁾ It has been found that electrophotographic paper can be obtained.

  When the charge density of the disaggregated pulp slurry filtrate of the electrophotographic paper according to the present invention disaggregated according to JIS P 8220 is less than 0.7 meq / g, the fixing of the sizing agent and the fine fibers to an appropriate pulp fiber Since fixing cannot be obtained, fine aggregates and aggregates are not sufficiently formed. Since agglomeration is not formed, the sizing agent is lost at the paper making stage, and the sizing is not expressed. As a result, in the printing with an electrophotographic printing machine, moisture fluctuation is likely to occur, and the problem of curling is likely to occur.

  On the contrary, when the charge density exceeds 1.4 meq / g, because the paper is made in a state where the effect of aggregating the pulp slurry through the aggregation of the additive chemicals and the aggregates in the raw material adjustment stage is strong, Anionic trash, fillers, and fine fibers are agglomerated in the electrophotographic paper, and the electrophotographic paper manufactured in such a state tends to have poor formation, uneven size effect, and curl. Develop problems.

  As described above, in order to put a cationic size fixing agent (sulfuric acid band) in the seed box 4 in the subsequent process, the charge density in the seed box 4 is adjusted with the cationic flocculant X3 added in the subsequent process. It is preferable that the charge density of the disaggregated pulp slurry filtrate obtained by disaggregating the electrophotographic paper obtained in accordance with JIS P 8220 is adjusted to 0.7 to 1.4 Meq / g.

  In the present invention, a cationic coagulant, a sizing agent, and a cationic flocculant are added in this order as a means for adjusting the charge density of the disaggregated pulp slurry filtrate to 0.7 to 1.4 Meq / g. As shown in the figure, a cationic coagulant with a relatively high charge density in the raw material pulp blending adjustment stage is used, and after adding a sizing agent, a cationic coagulant having a lower charge density than the previous cationic coagulant is used. It becomes possible.

The electrophotographic paper according to the present invention has a sticky size (conforming to JIS P 8122) of 0.10 to 0.35 seconds / (g / m ² ), preferably 0.12 seconds to 0.30 seconds. More preferably, it is the range of 0.13 second or more and 0.25 second or less.

If the hydrate size is less than 0.12 sec / (g / m ² ), the hydrophilicity is high and the equilibrium moisture content rises. When used in a copying machine, a difference in moisture content occurs between the front and back surfaces of the paper. Have a problem that makes it easy to curl. If the hydrate size exceeds 0.35 seconds / (g / m ² ), it is necessary to add an excessive amount of internal sizing agent and external sizing agent, which leads to contamination in the machine system and contamination of the after dryer.

  In addition, when the sizing degree is less than 0.10 seconds, a problem of curling due to insufficient size effect in the present invention appears. In addition, the ink absorbency in ink-jet recording that is frequently used in recent years has increased, so that feathering has deteriorated in the ink-jet recording method, making it impossible to distinguish fine characters or reading barcodes etc. And impairs practicality. On the other hand, if it exceeds 0.35 seconds, ink permeation slows down, causing bleeding between colors and deteriorating color image quality.

Here, the degree of squeecht sizing according to the present invention is the degree of sizing sizing according to JIS-P-8122: 1976 measured in a standard environment (temperature 23 ° C., relative humidity 50%) defined in JIS-P-8111: 1998. Is corrected based on the basis weight for recording. This is because the effect of the basis weight of the electrophotographic paper cannot be excluded if the Steecht sizing degree is used as it is. “Stichtish sizing degree” defined in the present invention is represented by the following formula (1).
Formula (1)
Sticky sizing degree = Sticky sizing degree (JIS-P-8122) ÷ Basis weight

  Furthermore, in the adjustment of the used paper pulp obtained from the used paper, NKP: 10-20, LKP: 50-70, MP: 10-40 in the adjustment of the raw material pulp by classification, beating treatment, etc. according to the selection of the used raw paper. In the production of electrophotographic paper that uses 70% by weight or more of the recycled paper pulp, it is not sufficient to select the used waste paper, and the cationic flocculant, sizing agent, cation In combination with the coagulant, it is possible to secure a sufficient degree of squeeze size and prevent curling.

  PCT15 or 20 (manufactured by Mutek) is typically exemplified as an on-line charge density measuring apparatus, and PCD03 (manufactured by Mutek) is exemplified as a portable charge density measuring apparatus. In this charge density measuring device, electricity is generated by the distortion of the surface charge of colloidal particles by introducing the sample into the cell of the test machine and the flow of the sample liquid between the cell cylinder and the piston when the upper and lower pistons are operated. Let The colloidal dissolved substance particles in the pulp suspension are charged with ions, and by using this, the charge requirement is measured by measuring polymer electrolyte.

  By adding 70% by weight or more of the ratio of waste paper pulp, ash content derived from waste paper is inevitably increased. Although most of the ash derived from waste paper is discharged out of the system in the process of reclaiming waste paper pulp from waste paper, fine ash components that are physically or chemically fixed to the fiber remain in the waste paper pulp. It is obtained by being used as a papermaking raw material, and has a higher adhesiveness with the raw material pulp than a virgin filler, and therefore brings about a synergistic effect of improving toner fixability when performing electrophotographic printing. Furthermore, by adjusting the main component of ash to calcium carbonate and white carbon by selecting the used paper as the raw material, it improves the opacity and whiteness of electrophotographic paper while blending 70% by weight or more of used paper pulp. Contribute.

  Further, it is preferable to use a cationic coagulant having a high charge density. Cationic coagulants with high charge density have good compatibility with neutral rosin sizing agents added in the subsequent process, have higher chemical yields than other neutral sizing agents, and improve the hydrate size with a low addition amount. Can be made.

  Furthermore, by combining a cationic flocculant lower than the cationic sizing agent added in the subsequent step, the yield of the neutral rosin sizing agent can be further improved, and an effective curling prevention effect can be brought about. .

  By adding a cationic coagulant with a high charge density in the raw pulp blending process, adding a sizing agent and a sizing agent in the subsequent process, and using a cationic flocculant with a lower charge density than the previous cationic coagulant, The effect of each chemical can be improved, contamination by anionic trash in the papermaking system can be prevented, wet end control in the papermaking machine becomes easier, operability is improved, and the resulting electrophotographic paper is In spite of the fact that the proportion of waste paper pulp is as high as 70% by weight or more, an electrophotographic paper having no curling and excellent in electrophotographic printability can be obtained.

Furthermore, preparation of raw materials and control of production conditions are performed in order to impart electrophotographic aptitudes such as copy aptitude and runnability. In order to prevent image distortion and maintain appropriate copy image density, a conductive agent such as sodium chloride, potassium chloride, styrene-maleic acid copolymer, quaternary ammonium salt, etc. is applied to the surface with a paper machine size press. The surface electrical resistance (according to JIS K 6911) is preferably 10 ⁹ to 10 ¹³ Ω (temperature 20 ° C., humidity 65% RH).

Next, examples of the present invention will be described.
To the raw material pulp mixed in the types and proportions shown in Table 1, the types, physical properties and addition amount (solid content) of the cationic coagulant, sizing agent, and cationic flocculant shown in Table 2 were added in this order. (The place of addition is also shown in Table 2.) A papermaking raw material was obtained, and this was made to obtain an electrophotographic paper.

A: Cationic coagulant NR-783 (1.45 Meq / g) manufactured by Hymo Co., Ltd.
SC-924 (5.4-7.2 Meq / g) manufactured by HAimo Co., Ltd.
Modified polyalkyleneimine A (15.2 Meq / g)
A polyalkyleneimine-modified product obtained by reacting polyethylenimine P-200 manufactured by Nippon Shokubai Co., Ltd. with a polycationic substance obtained by reacting epichlorohydrin and dimethylamine.
Modified polyalkyleneimine B (18.6 Meq / g)
A polyalkyleneimine-modified product obtained by reacting a polycationic substance obtained by reacting epichlorohydrin and dimethylamine with polyethyleneimine SP-1050 manufactured by Nippon Shokubai Co., Ltd.
Modified polyalkyleneimine C (17.5 Meq / g)
A polyalkyleneimine-modified product obtained by adjusting the polycationic substance and changing the charge density in the reaction of the polyalkyleneimine-modified product B.

B: sizing agent amylofax (neutral rosin) manufactured by Matsutani Chemical Industry Co., Ltd.
Harsize AK-720H (AKD) manufactured by Harima Chemicals

C: Cationic flocculant ND-270 (0.34-0.51 Meq / g) manufactured by Hymo Co., Ltd.
Modified polyalkyleneimine D (0.85 Meq / g)
A polyalkyleneimine modified product prepared by adjusting the polycationic substance and changing the charge density in the reaction of the modified polyalkyleneimine A.

D: Anionic flocculant FA-230 (1.13 to 1.38 Meq / g) manufactured by Hymo Co., Ltd.

  Table 3 shows the physical properties (quality data) of the obtained electrophotographic paper. Further, curling and twisting before and after the test copy, and running property (jam, ear fold, fixing wrinkle, double feeding between books) were evaluated, and the results are shown in Table 4.

(US tsubo)
Measured based on JIS P 8124.

(Paper thickness)
Measured based on JIS P 8118.

(Smoothness)
Measured based on JIS P 8119.

  (Air permeability)

  Measured based on JIS P 8117.

(Stiffness)
Measured based on JIS P 8143.

(Whiteness)
Measured based on JIS P 8148.

(Electrical resistance)
The surface electrical resistivity at 22 ° C. and 55% RH was measured for 24 hours under conditions of 22 ° C. and 55% RH, and the humidity-controlled recording paper was measured under the same environment according to JIS-K-6911. Is.

(ash)
Measured based on JIS P 8251.

(Stick Hide Size)
It measured based on JISP8122.

(Charge density)
(1) Collect 30 g of a dry sample and disperse using pure water.
Disaggregation condition absolutely dry: 30g
Pure water volume: 2000ml
Dissolution concentration: 1.5%
Disaggregation time: 10 minutes
Use disintegrator: Standard disintegrator (conforms to JIS P 8220)
(2) The sample after disaggregation is subjected to suction filtration (model number: 5A 70 mm, manufactured by ADVANTEC), and 10 ml of the filtrate is collected.
(3) The charge density of the sample of (2) was measured with a model: PCD03 manufactured by mutek.

(Curl suitable)
<Before copying>
-Curling degree The obtained electrophotographic paper is cut into A4 size, left at 22 ° C. and 55% RH for 24 hours, then cut into a size of 100 mm × 100 mm, with the felt surface (rolling surface) facing up. Evaluation was performed after standing for 4 hours or more. The curl was measured by placing each sample on a flat plate so that the inner surface of the curl was up and measuring the height of the four corners of each sample. The values shown in the table are absolute values of the average value of the heights of the four corners.

-Twist The obtained electrophotographic paper was cut into A4 size, and as shown in FIG. 2, the electrophotographic paper S was suspended and the distance L (absolute value) was measured to obtain the twist value.

<After copy>
-Curl degree Using a Ricoh copier (imageo MPC6000), monochrome printing with A4 landscape was performed, and the curl height maximum value (absolute value) at the four corners placed on the plane 10 minutes after printing using the 10th print sample. ) Was measured. Evaluation was performed according to the following criteria.

-Twist Using a Ricoh copier (imageioMPC6000), print black and white with A4 landscape, suspend the electrophotographic paper S as shown in Fig. 2 using the 10th print sample, and 10 minutes after printing The distance L (absolute value) was measured and used as the twist value.

(Runability data)
Using a Ricoh copier (image MPC6000), monochrome printing was performed with A4 landscape, and jamming troubles, ear folding, fixing wrinkles, and double feed between books were evaluated when 1000 sheets were printed.
○: Good with no jamming troubles, broken ears, fixing wrinkles, or double feed between books.
Δ: Some of jam troubles, broken ears, fixing wrinkles, and double feed between books cannot be suppressed, and are slightly defective.
×: Unusable because of jam trouble, broken ears, fixing wrinkles or double feed between books.

  The present invention is applicable as an electrophotographic paper and a manufacturing method thereof.

It is a flowchart for demonstrating the addition place of a cationic coagulant | flocculant, a sizing agent, and a cationic flocculant. It is a figure for demonstrating the measuring method of a twist degree.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Acceptance chest, 2 ... Compound chest, 3 ... Machine chest, 4 ... Seed box, 5 ... First fan pump, 6 ... Cleaner, 7 ... Screen, 8 ... Second fan pump, 9 ... Head box, 10 ... Carbonic acid Calcium receiving tank, 11 ... calcium carbonate addition tank, 12 ... double thickener, 30 ... hydrated silicate reception tank, 31 ... hydrated silicate addition tank, X1 ... coagulant, X2 ... sizing agent, X3 ... flocculant.

Claims (6)

An electrophotographic paper having an ash content (in accordance with JIS P 8251) of 6% or more obtained by papermaking a papermaking raw material containing 70% by weight or more of waste paper pulp,
In the papermaking raw material, a cationic coagulant, a sizing agent, and a cationic flocculant are added in this order,
The charge density of the disaggregated pulp slurry filtrate obtained by disaggregating the obtained electrophotographic paper according to JIS P 8220 is 0.7 to 1.4 Meq / g,
The rigid size (according to JIS P 8122) is 0.10 to 0.35 sec / (g / m ² ).
An electrophotographic paper characterized by that. The waste paper pulp is composed mainly of newspaper waste paper and / or magazine waste paper, and the composition ratio of the disaggregated pulp slurry is NKP: 10-20, LKP: 50-70, MP: 10-40,
The cationic coagulant is added in the raw material pulp blending adjustment stage,
The sizing agent is a neutral rosin sizing agent and is added in a later step different from the cationic coagulant,
The electrophotographic paper according to claim 1. The cationic coagulant is
One or more amines selected from ammonia, primary amines, secondary amines, and tertiary amines;
A polycationic substance mainly comprising a compound represented by the following formula (1);
A polyalkyleneimine-modified product having a structural unit represented by the following formula (2) obtained by reacting a polyalkyleneimine having a molecular weight of 10,000 to 70,000,
In the blending adjustment stage of the raw material pulp, 1.0 to 3.0 kg / pulpton is added as a solid content,
The electrophotographic paper according to claim 1 or 2.

However, P is an epoxy group or a halohydrin group, p is an integer of 0 to 20, R1 to R4 are hydrogen, an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group, or a benzyl group, and X1 to X2 Is an anion.

However, p is an integer of 0-20, R1-R4 is hydrogen, a C1-C3 alkyl group, a hydroxyalkyl group, or a benzyl group, and X1-X2 is an anion. The polyalkyleneimine is polyethyleneimine;
The electrophotographic paper according to claim 3. The electrophotographic paper according to any one of claims 1 to 4, wherein the cationic coagulant, the sizing agent, and the cationic flocculant are added at the following locations and in the following addition amounts. .
The cationic coagulant is added in an amount of 1.0 to 3.0 kg / pulpton as a solid content in the raw material pulp blending adjustment stage.
The sizing agent is added in a solid content of 3.0 to 8.0 kg / pulpton in a seed box.
The cationic flocculant is added in an amount of 0.1 to 5.0 kg / pulpton as a solid content in a subsequent step after the sizing agent is added. A method for producing an electrophotographic paper having a ash content (in accordance with JIS P 8251) of 6% or more by papermaking a papermaking raw material containing 70% by weight or more of waste paper pulp,
To the papermaking raw material, a cationic coagulant, a sizing agent, and a cationic flocculant are added in this order,
The charge density of the disaggregated pulp slurry filtrate obtained by disaggregating the obtained electrophotographic paper according to JIS P 8220 is 0.7 to 1.4 Meq / g, and the hydrate size (according to JIS P 8122) is 0. 10 to 0.35 seconds / (g / m ² )
An electrophotographic paper manufacturing method characterized by the above.

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