JP2002088697A - Pulp molded product - Google Patents

Abstract

(57) [Problem] To provide a pulp molded article in which the occurrence of uneven coloring in the case of coloring during production is prevented. SOLUTION: In a pulp molded article containing a pulp fiber and a coloring agent and colored to a predetermined color by the coloring agent, a pulp in which a fixing agent and an inorganic filler are blended as a coloring unevenness inhibitor of the coloring agent. Molded body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulp molded article in which the occurrence of uneven coloring is prevented and a method for producing the same.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 9-143900 discloses a postcard paper containing a filler having a predetermined oil absorption for the purpose of preventing the repelling phenomenon of an aqueous ink. Is described.

[0003] However, the technique described in the above publication is intended to solve the problem of printing on manufactured paper, and the problem of preventing color unevenness when coloring is performed at the time of manufacturing paper. No consideration.

[0004] Accordingly, an object of the present invention is to provide a pulp molded article in which the occurrence of uneven coloring in the case of coloring during production is prevented.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a pulp molded article containing a pulp fiber and a colorant and colored to a predetermined color by the colorant. The object has been achieved by providing a pulp molded article in which an inorganic filler is blended.

The present invention also provides, as a preferred method for producing the pulp molded article, a pulp slurry obtained by adding and mixing the colorant to the slurry containing the pulp fibers and then adding and mixing the inorganic filler. The present invention also provides a method for producing a pulp molded article, which is supplied to a papermaking mold and papermaking is performed by a wet papermaking method.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pulp molded article of the present invention will be described below based on preferred embodiments. As the pulp fiber used in the present invention, the same pulp fibers as those conventionally used for this type of molded article are used, and examples thereof include bleached or unbleached coniferous or hardwood chemical pulp, cotton pulp, linter pulp, and the like. And the like. Also,
It is also possible to use waste paper pulp made from used printed waste paper such as newsprint, medium-quality paper, high-quality paper, or deinked waste paper pulp. One or more of these pulp fibers can be used.

[0008] The amount of pulp fibers in the pulp molded article is 55 to 99.9% by weight, particularly 70 to 95% by weight.
Is preferred from the viewpoints that stable papermaking is possible, that a molded article having a uniform thickness and excellent in smoothness of the inner and outer surfaces can be produced, and that the occurrence of uneven coloring is prevented. When the amount of the pulp fiber is from 80 to 94% by weight, the occurrence of uneven coloring is further prevented, and the molded article is uniformly colored.

The type of the coloring agent used in the present invention is not particularly limited as long as it can impart some coloring to the pulp molded article. Examples of colorants include
Organic pigments, inorganic pigments, metallic pigments, dyes, and the like are included. Examples of the organic pigment include a phthalocyanine pigment, an azo pigment, a condensed polycyclic pigment, and the like. As inorganic pigments,
Titanium dioxide, iron oxide, pearl mica, barium sulfate,
Titanium black and the like. As metallic pigments,
Examples include plate-like iron oxide, graphite, and aluminum powder.
Examples of the dye include various dyes such as acid dyes, basic dyes, and oily dyes. Rebasel Yellow R (yellow dye), Rebasel Scarlet 4BS (red dye), Rebasel Black G (black dye), Kaka Perfect Orange G
(Red-yellow dye) and the like. Of these colorants,
High yield to pulp fiber, ease of wastewater treatment,
It is preferable to use each of the above-mentioned pigments from the viewpoint of the coloring property, heat resistance and weather resistance of the molded article. Particularly, from the viewpoint of fixability, it is more preferable to use an anionic pigment.

The colorant has an average particle size of 0.001 to
It is preferable that the thickness be 1 μm, particularly 0.01 to 0.7 μm, from the viewpoint that a molded article having excellent appearance with excellent coloring power and hiding power can be obtained. The average particle diameter is measured by microscopic observation and sedimentation analysis (hereinafter, the average particle diameter is a value measured by this method). The coloring agent may be in various shapes such as a sphere, a plate, and a column,
The maximum length is used as the particle size, and the average value of the maximum length is used as the average particle size (hereinafter, the average particle size means this definition).

The amount of the coloring agent in the pulp molded article depends on the type of the coloring agent, the degree of coloring of the molded article, and the like.
0.01 to 5 parts by weight with respect to 100 parts by weight of pulp fiber,
In particular, the amount is preferably 0.05 to 2.5 parts by weight from the viewpoint of improving the appearance of the pulp molded article and suppressing outflow of the colorant into white water.

The pulp molded article of the present invention contains an inorganic filler as a colorant unevenness inhibitor. Incorporation of the inorganic filler improves the fixability of the colorant to the pulp fiber during production of the pulp molded article, prevents the occurrence of uneven coloring, and allows the colored article to uniformly color the molded article.

Examples of the inorganic filler include silicates such as aluminosilicate and talc, carbonates such as calcium carbonate, mica, kaolin clay, aluminum hydroxide, zinc oxide, calcined clay, silica and the like. The appropriate one is used in relation to Particularly, calcium carbonate and aluminosilicate, which are inorganic fillers having an anionic surface charge, are preferable.

The inorganic filler has an average particle size of 0.1
The thickness is preferably from 30 to 30 µm, particularly from 0.5 to 10 µm, from the viewpoints of preventing color unevenness and maintaining the mechanical strength of the molded product, particularly the impact strength. Furthermore, the average particle size of the inorganic filler,
It is preferable that the average particle diameter is larger than the average particle diameter of the colorant, since the fixation of the colorant to the inorganic filler works effectively and the color unevenness is further prevented. From the viewpoint of further preventing color unevenness, the average particle size of the inorganic filler is 5% of the average particle size of the colorant.
The ratio is preferably from 300 to 300 times, particularly preferably from 10 to 100 times.

The amount of the inorganic filler in the pulp molded article is preferably 5 to 30 parts by weight, more preferably 7 to 25 parts by weight, especially 10 to 20 parts by weight based on 100 parts by weight of the pulp fiber. It is preferable from the viewpoints of easy toning, maintenance of mechanical strength of the molded article, and suppression of hydrophilicity of the molded article.

The pulp molded article of the present invention contains, in addition to the above-mentioned inorganic filler, a fixing agent as a coloring unevenness suppressing agent for the coloring agent. By using a fixing agent and an inorganic filler in combination as a coloring unevenness inhibitor, during the production of a pulp molded article, the fixability of the coloring agent to pulp fibers is further improved, and the occurrence of coloring unevenness is further prevented. The molded article is more uniformly colored. Examples of the fixing agent include a sulfuric acid band, polyaluminum chloride, starch, polyacrylamide, polyamine polyamide / epichlorohydrin resin, and melamine / formaldehyde resin, and an appropriate one is used in relation to a coloring agent used. In particular, as described below, it is preferable to use a sulfuric acid band or polyaluminum chloride as the fixing agent.

The amount of the fixing agent in the pulp molded product is 0.2 to 3 parts by weight, preferably 0.25 to 1.5 parts by weight, especially 0.3 to 1 part by weight based on 100 parts by weight of the pulp fiber.
It is preferable that the amount be part by weight from the viewpoint of improving the fixability of the colorant to the pulp fiber and preventing the occurrence of uneven coloring.

The pulp molded article contains, in addition to the above-mentioned pulp fiber, colorant, fixing agent and inorganic filler, various components conventionally used in this type of molded article.
A desired function may be developed. Examples of such components include sizing agents, water repellents, paper strength agents, pitch control agents, foam inhibitors, fixing aids, and the like.
These components may be added internally to the pulp slurry, or may be added externally during or after the production of the molded article.

Next, a preferred method of manufacturing the pulp molded article of the present embodiment will be described with reference to FIG. FIG. 1 sequentially shows a papermaking step and a dewatering step in a method for producing a bottle-shaped pulp molded article having a screw portion on the outer periphery of a mouth and neck. In FIG. 1, (a) is a pulp slurry injection and suction dehydration step, (b) is a core insertion step, (c) is a pressure dehydration step, and (d) is a step of opening a papermaking mold. In addition, the screw part is omitted in FIG. 1 for simplicity.

In the present manufacturing method, a pulp slurry is supplied under pressure into the cavity of a papermaking mold comprising a set of molds, and a cavity having a predetermined shape is formed by combining the molds. After forming a water-containing molded body on the inner surface of the molded body, insert a scalable hollow core into the molded body, then supply a predetermined fluid into the core to expand the core, The molded body is pressed toward the inner surface of the cavity by the expanded core to perform pressure dehydration.

More specifically, first, as shown in FIG. 1 (a), a papermaking die 1 comprising two split dies 2 and 3 and forming a cavity 4 having a predetermined shape by combining the split dies. Prepare The cavity 4 communicates with the outside of the papermaking mold 1 through a slurry injection port 5 opened to the outside. The inner surface of the cavity 4 is covered with a net (not shown) having a mesh of a predetermined size. Each split mold 2, 3 has its interior (that is, the inner surface of the cavity 4)
And a plurality of communication passages 6 for communicating the outside with the outside. Each communication path 6 is connected to suction means (not shown) such as a suction pump. In FIG. 1, the thread portions formed on the split dies 2 and 3 are omitted.

First, a predetermined amount of pulp slurry is injected into the cavity 4 through the slurry inlet 5 before the core is inserted into the cavity 4. The pulp slurry contains the above-mentioned pulp fiber, colorant and inorganic filler. Along with the injection of the pulp slurry, the inside of the cavity 4 is sucked under reduced pressure through the communication path 6 toward the outside of the papermaking mold 1 to suck moisture in the pulp slurry and to form a pulp on the net covering the papermaking surface, ie, the inner surface of the cavity 4. The fibers are deposited. As a result, a water-containing molded body 7 formed by depositing pulp fibers is formed on the net. By injecting the pulp slurry under pressure, the pulp slurry filled in the cavity 4 is convected, and the pulp fibers are easily deposited on the net with a uniform thickness. From the viewpoint of depositing pulp fibers with a more uniform thickness and coloring more uniformly, the concentration of pulp fibers in the pulp slurry is preferably 0.1 to 3%, particularly preferably 0.3 to 2%.

In the preparation of a pulp slurry as a papermaking raw material, it is preferable to add and mix a colorant to a slurry containing pulp fibers and then add and mix an inorganic filler from the viewpoint of preventing color unevenness. In particular, at any stage before the addition of the inorganic filler, the above-mentioned fixing agent is added and mixed to make the zeta potential of the pulp fiber in the finally obtained pulp slurry 0 to -15 mV, particularly -3 to -10 mV. Is preferred from the viewpoint of further preventing color unevenness. The order of adding the fixing agent may be, for example, the following (a) to (c). (a) (1) Colorant (2) Fixing agent (3) Inorganic filler (b) (1) Fixing agent (2) Coloring agent (3) Inorganic filler (c) (1) Fixing agent (2) Coloring agent ( 3) Inorganic filler (4)
Fixing agent

Among the above-mentioned (a) to (c), from the viewpoint of increasing the coloring power and forming the flocs of the fibers smaller, thereby improving the color clarity and color forming properties of the colorant, (a) or (c) It is preferred to use (b). Before and after the addition of the fixing agent, the above-mentioned sizing agent, water repellent, paper strength enhancer, pitch control agent, foam inhibitor, fixing aid and the like can be added as necessary.

The zeta potential of the pulp fiber is measured by a streaming potential method capable of measuring a pulp slurry. In the present invention, the papermaking zeta potential measuring device SZP 0
4 (trade name) [manufactured by Nippon Luft Co., Ltd.].

In particular, an acidic sulfate band or polyaluminum chloride is used as a fixing agent, and an alkaline carbonate or the like is used as an inorganic filler.
C) to a neutral region, for example 6.0 to 8.5,
It is preferable because the deterioration of the obtained molded article with time is reduced and the treatment of white water is facilitated. Above all, it is preferable to use a sulfate band or polyaluminum chloride as a polyvalent metal salt as a cationizing agent as a fixing agent.

The formed body 7 thus formed is subjected to a pressure dehydration step. First, as shown in FIG. 1 (b), the expandable and contractible hollow core 8 is inserted into the molded body 7 in a contracted state while the papermaking mold 1 is sucked from the inside to the outside. I do. In the present invention, the expansion and contraction means the core 8
Includes a case in which the volume changes due to expansion and contraction, and a case in which the volume changes by supplying a fluid to or removing a fluid from the inside while the core 8 itself does not expand and contract. Examples of the former are natural rubber, urethane,
Examples include a core made of an elastic material such as a fluorine-based rubber, a silicone-based rubber, or an elastomer, and examples of the latter include plastic materials such as polyethylene and polypropylene, and aluminum and silica deposited on a film of these plastic materials. Examples include a film, a film in which an aluminum foil is laminated on a film of these plastic materials, and a core made of a flexible material such as papers and cloths. In the present embodiment, a bag-shaped (balloon-shaped) core made of a stretchable elastic material is used as the core 8.

Next, as shown in FIG. 1C, a predetermined fluid is supplied into the core 8 to expand the core 8, and the expanded core 8 causes the molded body 7 in a water-containing state to be formed on the papermaking surface. That is, it is pressed toward the inner surface of the cavity 4. As a result, the pressurized dehydration of the molded body 7 proceeds, and the inner surface shape of the cavity 4 is transferred to the molded body 7. In this case, since the molded body 7 is pressed from the inside toward the inner surface of the cavity 4, even if the shape of the cavity 4 is complicated, the molded body 7 is accurately transferred to the molded body 10 on the inner surface of the cavity 4. Become. Further, it is possible to easily manufacture a deep-bottom molded body whose side wall rises almost vertically. As the fluid used to expand the core 8, for example, air (pressurized air), hot air (heated pressurized air), superheated steam, oil (heated oil), and other various liquids are used. In particular, it is preferable to use air, hot air, or superheated steam from the viewpoint of operability and the like. The pressure for supplying the fluid is 0.01 to 5 MPa, especially 0.1 to 3 MPa.
a is preferred.

When the molded body 7 can be dewatered to a predetermined moisture content and the shape of the inner surface of the cavity 4 is sufficiently transferred to the molded body 7, the fluid in the core 8 is drained as shown in FIG. The core 8 is reduced. Next, the reduced core 8 is taken out of the molded body 7, and the papermaking mold 1 is further opened to take out the water-containing molded body 7 having a predetermined moisture content.

In the above-mentioned pressurized dehydration step, instead of pressurizing and dehydrating the water-containing molded body 7 by pressing using the core, a pressurized air or pressurized steam (dry steam or superheated steam) or the like is used. The pressurized fluid may be supplied into the molded body 7 in a water-containing state, and the molded body 7 may be depressurized and dehydrated by pressing the molded body 7 toward the inner surface of the cavity.

The removed molded body is then subjected to a heating and drying step. In the heating and drying process, papermaking and dehydration are not performed,
Almost the same as the papermaking step and the dewatering step shown in FIG. 1 except that a heated mold in a heated state and another core having higher heat resistance and durability than the core used in the pressure dewatering step are used. Is performed. The reason for using a core having higher heat resistance and durability than the core used in the pressure dehydration step is that, in the heating and drying step, the core is expanded and contracted under more severe conditions than in the pressure dehydration step. It is.

First, a heating mold is formed separately by forming a cavity having a shape corresponding to the outer shape of the pulp molded article to be molded by combining a set of split molds, and the heating mold is heated to a predetermined temperature. deep. In this embodiment, the cavity shape of the heating mold and the cavity shape of the papermaking mold are the same. Into the cavity of the heating mold in a heated state, a water-containing molded body dehydrated to a predetermined water content is loaded.

Next, a core 8 different from the core 8 used in the pressure dehydration step shown in FIGS. 1B and 1C is inserted into the molded body.
A fluid is supplied into the core to expand the core, and the expanded core presses the molded body toward the inner surface of the cavity. The material of the core and the supply pressure of the fluid can be the same as in the pressure dehydration step. In this state, the molded body is dried by heating. In particular, by using a heating fluid such as heated air or superheated steam as a fluid to be supplied to the core, drying is performed more efficiently, and drying efficiency is further improved. When the molded body is sufficiently dried, the fluid in the core is drained, and the core is reduced and taken out. Further, the heating mold is opened, and the pulp molded product is taken out.

The bottle-shaped pulp molded article manufactured in this way has no joint at the mouth, neck, body and bottom, and the mouth, neck, body and bottom are integrally formed. It has a good appearance. And this molded body,
By incorporating an inorganic filler as a color unevenness inhibitor of the colorant, the fixability of the colorant to the pulp fiber is improved, the occurrence of color unevenness is prevented, and the colorant allows the molded body to have a predetermined color evenly. It is colored.

The present invention is not limited to the above embodiment.
For example, the present invention can be applied to not only a bottle-shaped molded body but also a box-shaped carton-shaped molded body and molded bodies of other shapes. Further, in addition to the shape of the container used to store the contents, various shapes such as objects such as ornaments can be freely designed.

The method for producing the pulp molded article of the present invention is not limited to the above-mentioned method, and various methods are appropriately selected according to the shape of the molded article to be molded.

[0037]

EXAMPLES In the following examples, "parts" and "%" mean "parts by weight" and "% by weight", respectively, unless otherwise specified.

[Examples 1 to 5] Softwood bleached chemical pulp 30
And 70 parts of bleached bleached chemical pulp are dispersed in water to form a slurry, to which a colorant (anionic pigment, copper phthalocyanine blue, average primary particle size 0.1 μm) is added at 0.075% by weight of pulp and mixed. Was. Next, the fixing agent shown in Table 1 was added and mixed in an amount shown in Table 1 with respect to pulp weight, and mixed.
Thereafter, the inorganic fillers shown in Table 1 were added to the pulp weight in Table 1.
Was added and mixed to obtain a pulp slurry. The pulp concentration in the pulp slurry was adjusted to 1%. The pulp slurry had a Canadian Standard Freeness of 400 ml. Using this pulp slurry as a papermaking raw material, a bottle-shaped pulp molded article having a screw portion on the outer periphery of the mouth and neck was manufactured by the method shown in FIG.

Example 6 A pulp molded article was manufactured in the same manner as in Example 1 except that a pulp slurry was prepared by adding 1% by weight of pulp to the fixing agent.

Example 7 Example 1 was repeated except that the order of adding the colorant and the inorganic filler was changed.
A pulp molded article was produced in the same manner as in the above.

Comparative Example 1 A pulp molded article was manufactured in the same manner as in Example 1 except that a pulp slurry was prepared without adding a fixing agent and an inorganic filler.

[Evaluation of Performance] The degree of prevention of uneven coloring was visually evaluated for the obtained pulp molded article. The evaluation criteria are as follows. Table 1 shows the results. Table 1 also shows the zeta potential of pulp fibers and the pH of the pulp slurry in the pulp slurry used. A: No uneven coloring is observed. ：: No coloring unevenness is observed. Δ: Color unevenness is slightly observed. X: Uneven coloring is observed and cannot be used as a product.

[0043]

[Table 1]

As is clear from the results shown in Table 1, the pulp molded articles (products of the present invention) of each of the examples in which a fixing agent as a coloring unevenness inhibitor of the coloring agent and an inorganic filler were blended were used. It can be seen that the occurrence of uneven coloring is effectively prevented as compared with the molded article of the comparative example in which no compounding is performed.

[0045]

According to the pulp molded article of the present invention, it is possible to prevent the occurrence of color unevenness when coloring during production.

[Brief description of the drawings]

FIG. 1 is a process diagram sequentially showing a papermaking and dewatering step of the method for producing a pulp molded article of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper making mold 2, 30 split mold 4 Cavity 5 Slurry inflow port 6 Cavity 7 Molded object 8 Core

[Procedure amendment]

[Submission date] September 17, 2001 (2001.9.1
7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

SUMMARY OF THE INVENTION The present invention relates to a pulp molded article containing a pulp fiber and a coloring agent, which is colored to a predetermined color by the coloring agent . fixing agent and Ani consisting agent
The object has been achieved by providing a pulp molded article in which an inorganic filler having an ON surface charge is blended.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

The present invention also provides, as a preferred method of manufacturing the pulp molded article, a method of adding the colorant to the slurry containing the pulp fibers and then adding the fixing agent.
An object of the present invention is to provide a method for producing a pulp molded article in which a pulp slurry obtained by adding and mixing and then adding and mixing the inorganic filler is supplied to a papermaking mold and papermaking is performed by a wet papermaking method. Further, the present invention provides the pulp molding
As a preferred method for producing a molded article, the pulp fiber is
After adding and mixing the fixing agent to the slurry containing
And then mixing the inorganic filler.
The pulp slurry obtained in this way is supplied to a papermaking mold and
Manufacturing method of pulp molded article made by papermaking method
It provides the law.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

As the inorganic filler, a surface charge of an anion is used.
Calcium carbonate and alumino, which are inorganic fillers
A silicate or the like is used, and an appropriate one is used in relation to a coloring agent to be used .

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

The pulp molded article of the present invention contains, in addition to the above-mentioned inorganic filler, a fixing agent as a coloring unevenness suppressing agent for the coloring agent. By using a fixing agent and an inorganic filler in combination as a coloring unevenness inhibitor, during the production of a pulp molded article, the fixability of the coloring agent to pulp fibers is further improved, and the occurrence of coloring unevenness is further prevented. The molded article is more uniformly colored. As a fixing agent, a sulfate band as a polyvalent metal salt as a cationizing agent
And polyaluminum chloride . An appropriate one is used in relation to a coloring agent to be used .

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

In particular, as a fixing agent, as a cationizing agent
Polyvalent metal salt with an alkaline carbonate such as and an inorganic filler using a sulfuric acid band or polyaluminum chloride, adjusted pH of the pulp slurry (25 ° C.) neutral range, for example, 6.0 to 8.5 of This is preferable because the resulting molded article is less likely to deteriorate with time and the treatment of white water is facilitated .

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Deleted

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction contents]

[0043]

[Table 1]

Continued on the front page (72) Inventor Mitsuyuki Kubo 2606 Akabane, Kaga-cho, Haga-gun, Tochigi Prefecture F-term in the Kao Corporation Research Laboratory 4L055 AF09 AG08 AG11 AG12 AG18 AG26 AG39 AG96 AH01 AH02 AH09 BF08 EA31 EA35 FA11 GA05

Claims (8)

[Claims] 1. A pulp molded article containing a pulp fiber and a coloring agent and colored to a predetermined color by the coloring agent, wherein a fixing agent and an inorganic filler are blended as a coloring unevenness inhibitor of the coloring agent. Pulp molded product. 2. The method according to claim 1, wherein the ratio of the colorant is 10%.
The pulp molded article according to claim 1, wherein the amount is 0.01 to 5 parts by weight based on 0 parts by weight, and the ratio of the inorganic filler is 5 to 30 parts by weight based on 100 parts by weight of the pulp fiber. 3. The method according to claim 1, wherein the ratio of the fixing agent is 10%.
The pulp molded article according to claim 1 or 2, wherein the amount is 0.2 to 3 parts by weight based on 0 part by weight. 4. The pulp molded article according to claim 1, wherein the average particle diameter of the inorganic filler is larger than the average particle diameter of the coloring agent. 5. The colorant has an average particle size of 0.001 to 1
μm, and the average particle size of the inorganic filler is 0.1 to 3
The pulp molded article according to claim 4, which has a thickness of 0 µm. 6. The method for producing a pulp molded article according to claim 1, wherein the colorant is added to and mixed with the slurry containing the pulp fibers, and then the inorganic filler is added and mixed. Is supplied to a papermaking mold and papermaking is performed by a wet papermaking method. 7. At any stage before the addition of the inorganic filler, a predetermined amount of the fixing agent is added and mixed so that the zeta potential of the pulp fiber in the finally obtained pulp slurry is 0 to −15 mV. Item 7. The method for producing a pulp molded article according to Item 6. 8. The method for producing a pulp molded article according to claim 6, wherein the pH (25 ° C.) of the pulp slurry is 6.0 to 8.5.