JP2001355200A - Method for producing pulp-molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a pulp-molded article, capable of effectively producing the molded article reduced in unevenness of wall thickness in the vertical direction. SOLUTION: This method for producing the pulp-molded article has a paper making process where a pulp slurry is aspirated through suction pipes 14 so that a pulp layer 15 is formed on the inner surface of a paper making mold 10, after split mold sections 11, 12 having suction pipes 14 are assembled to form the paper making mold 10 and supplying a cavity 13 of the mold 10 with the pulp slurry which has a predetermined supplying concentration is started, wherein a concentration of the pulp slurry in the cavity 13 at the initial stage or/and the final stage where the pulp layer 15 is formed in the paper making process is controlled so as to be lower than the above predetermined supplying concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a pulp molded article.

[0002]

2. Description of the Related Art A split mold provided with a suction path is assembled into a papermaking mold, and after the supply of pulp slurry into the cavity of the papermaking mold is started, the pulp slurry is passed through the suction path. There is a method for producing a pulp molded article provided with a paper making step of forming a pulp layer on the inner surface of the paper making mold by sucking the paper. In the paper making step of this manufacturing method, when the amount of slurry in the cavity at the beginning of supply of the pulp slurry to the cavity or after the completion of the supply is small, the cavity is sufficiently filled with the pulp slurry and the paper is made through the suction path. Since the stirring effect of the pulp slurry is insufficient as compared with the case where the pulp slurry is used, solid components such as pulp in the pulp slurry tend to settle naturally.
Also, at the time of sedimentation, moisture is more easily sucked,
The slurry concentration increases. For this reason, the thickness of the lower portion of the molded body tends to be thicker than the upper portion, and in particular, a bottle shape having a body portion rising suddenly upward from the bottom portion,
This tendency is large when a hollow molded body such as a carton type is formed, which has been one of the problems in forming such a hollow molded body.

Accordingly, it is an object of the present invention to provide a method for manufacturing a pulp molded article capable of efficiently producing a pulp molded article with reduced thickness unevenness in the vertical direction.

[0004]

Means for Solving the Problems The present inventors have proposed that the concentration of the pulp slurry in the cavity at the initial stage and / or the final stage of the formation of the pulp layer in the paper making process is made lower than the set supply concentration of the supplied pulp slurry. It has been found that the thickness unevenness in the vertical direction of the molded body can be suppressed.

The present invention has been made on the basis of the above-mentioned findings. A split mold having a suction path is assembled into a papermaking mold, and the supply of pulp slurry having a predetermined set supply concentration into the cavity of the papermaking mold is started. After that, in the method for producing a pulp molded article comprising a papermaking step of forming a pulp layer on the inner surface of the papermaking mold by sucking the pulp slurry through the suction path, the initial stage of forming the pulp layer in the papermaking step or The object has been achieved by providing a method of manufacturing a pulp molded article in which the concentration of the pulp slurry in the cavity is lower than the set supply concentration of the supplied pulp slurry.

Further, according to the present invention, a split mold having a suction path is assembled to form a papermaking mold, and after the supply of a pulp slurry having a predetermined set supply concentration into a cavity of the papermaking mold is started,
In the method for producing a pulp molded article having a papermaking step of forming a pulp layer on the inner surface of the papermaking mold by suctioning the pulp slurry through the suction path, the pulp slurry supplied into the cavity may have a composition Two different
One or more pulp slurries, wherein after the supply of one pulp slurry is started, another pulp slurry is supplied, and at least after the supply of the last pulp slurry into the cavity is completed, the last pulp slurry is diluted into the cavity. -The above object has been achieved by providing a method for producing a pulp molded article which supplies a fluid for stirring.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing a pulp molded article (hereinafter, also simply referred to as a molded article) of the present invention will be described based on preferred embodiments with reference to the drawings.

FIG. 1 schematically shows a papermaking mold and a pulp slurry supply system used in a papermaking process in one embodiment of the method for producing a molded article of the present invention. In addition,
In the figure, the papermaking mold is shown as one split mold.

In the present embodiment, a molded body is manufactured using two types of pulp slurries having different components as described later. For this reason, as shown in the figure, two pulp slurry supply systems are provided in two systems, A and B, and a pulp slurry dilution fluid described below (hereinafter also referred to as a dilution fluid).
A system C for supplying the water is also provided. Then, these three types of fluids can be supplied from one system D through the opening of the papermaking mold. Note that V shown in FIG.
1 to V4 are valves. The system E is a system for supplying air or water vapor into the cavity during dehydration. Split mold 1
A plurality of suction paths 14 are provided in 1.
The inner surface of each split mold 11 is covered with a papermaking net (not shown) having a mesh of a predetermined size.

FIGS. 2A to 2G show schematic steps of a method for manufacturing a molded article according to the present embodiment.
(A) is a diluting fluid injection step, (b) is a first pulp slurry injection and dehydration step, (c) is a first pulp slurry dehydration and second pulp slurry injection step,
(D) is a dewatering step of the second pulp slurry and a water injection step after the injection of the second pulp slurry, (e) is a core insertion step, (f) is a pressurization / dehydration step, and (g) is a dewatering step. This is a molding process.

First, the concentration of the pulp slurry in the cavity C at the initial stage of the formation of the pulp layer in the paper making process is made lower than the set supply concentration of the first pulp slurry. In particular, in the present embodiment, the concentration of the pulp slurry in the cavity C when the water level in the cavity C rises is increased in terms of effectively suppressing the thickness unevenness in the vertical direction in the initial stage of the formation of the pulp layer and making the thickness uniform. The concentration is set lower than the set supply concentration of the first pulp slurry.

In this embodiment, the valves V1 to V4 are operated so that only the dilution fluid can be supplied from the system C in FIG.
Then, as shown in FIG. 2 (a), a pair of split dies 11, 1
By abutting 2, the dilution fluid W is injected under pressure into the cavity 13 from the upper opening of the papermaking mold 10 in which the cavity 13 having a shape corresponding to the outer shape of the molded article to be molded is formed. For example, a pump is used for pressurized injection of the dilution fluid W. The pressure of the pressurized injection of the dilution fluid is preferably 0.01 to 5 MPa, more preferably 0.01 to 3 MPa.

As the diluting fluid, water is preferably used from the viewpoint of the appearance of the outer surface of the molded article and the cleanability of the piping, but hot water can also be used from the viewpoint of increasing the dewatering efficiency. When hot water is used, 35 to 90 ° C, especially 4
It is preferable to use warm water at 5 to 80 ° C. In addition, it is preferable to use, for example, already supplied pulp slurry white water from the viewpoint of reducing the amount of water used and the amount of drainage. Further, as the diluting fluid, for example, a pulp slurry set to a low concentration in advance can be used. In this case, the concentration of the pulp slurry as a pulp slurry diluting fluid is 50% or less, preferably 1% by weight or less, of the concentration of the supplied pulp slurry (set supply concentration). As the concentration of the supplied pulp slurry increases, the concentration of the pulp slurry as the diluting fluid preferably decreases. Further, as a fluid for diluting the pulp slurry, a fluid containing a detergent or various additives for adding functions can be used.

The injection amount of the diluting fluid can be appropriately set according to the size and shape (cavity capacity) of the molded article to be molded and the set supply concentration of the first pulp slurry. When the supply concentration is 1% by weight or more, the injection amount Vw of the dilution fluid is (1/1).
4) It is preferable that ρs · Vc <Vw <8Vc.
Here, this numerical range is calculated based on the pipe length and the cavity volume in the supply path of the diluting fluid having three valves in the supply path as shown in FIG. If the injection amount Vw of the diluting fluid is (以下) ρs · Vc or less, the ratio of the maximum thickness to the minimum thickness (maximum thickness / minimum thickness) of the compact is a preferable range. 0-3.0
, And the thickness unevenness of the molded body becomes so severe that burning occurs during drying, drying efficiency is reduced, and the compressive strength of the obtained molded body is reduced. Further, when the injection amount Vw of the diluting fluid is equal to or more than eight times the cavity volume Vc, the time required for the papermaking process becomes longer. Here, ρs is the set supply concentration (% by weight) of the supplied pulp slurry,
Vc is the volume of the cavity, and Vw is the injection amount of the dilution fluid. Specifically, for example, when the pulp slurry concentration ρs in the cavity before injecting water as a dilution fluid is 2% by weight and the volume Vc of the cavity is 1 liter, the water injection amount Vw is 0. It is preferable that 0.5 <Vw <8 liters.

After injecting a predetermined amount of the dilution fluid W, FIG.
The valves V1 and V2 are operated so that only the first pulp slurry I can be supplied from the system A. Then, as shown in FIG. 2B, the first pulp slurry I is injected under pressure to a predetermined amount in the cavity 13. In the present embodiment, since the first pulp slurry I is injected with the dilution fluid before the injection, the slurry in the cavity 13 is diluted. For example, a pump is used for pressure injection of the first pulp slurry I. The pressure of the first pulp slurry I under pressure is preferably 0.01 to 5 MPa, more preferably 0.01 to 3 MPa. The injection of the first pulp slurry I is preferably performed after the injection of the dilution fluid W. However, depending on the setting of the valve V1, during the injection of the dilution fluid, simultaneously with the injection of the dilution fluid, or the injection of the dilution fluid. It can also be done before injection. When the injection of the diluting fluid and the first pulp slurry is performed in parallel, a stirring effect is obtained in addition to the dilution, so that the diluting fluid acts as a diluting / stirring fluid.

The set supply concentration of the first pulp slurry is preferably 0.1 to 6% by weight, and 0.5 to 6% by weight.
More preferably, it is 3% by weight. If the amount is less than 0.1% by weight, a uniform thickness may not be obtained and molding failure may occur. If the amount exceeds 6% by weight, the injection amount of the diluting fluid may be reduced in order to obtain the effect of diluting the pulp slurry in the cavity. It has to be increased, which requires an injection time. In particular, setting the set supply concentration to 0.5% by weight or more is effective for stabilizing the formability, and setting the concentration to 3% by weight or less can improve the thickness distribution in the height direction. .

As the pulp fibers used in the first pulp slurry, those usually used in this type of pulp molded article can be used. In addition, by using pulp fibers described below, the obtained molded article can have characteristics as described below. In addition, the first pulp slurry is prepared by adding powders or fibers of inorganic materials such as talc and kaolinite, inorganic fibers such as glass fibers and carbon fibers, thermoplastic synthetic resins such as polyolefins, non-wood or plant in addition to pulp fibers and water. It may contain components such as fiber and polysaccharide. The amount of these components is 1 to 70% by weight, especially 5% by weight based on the total amount of the pulp fiber and the components.
Preferably, it is about 50% by weight.

In the method of manufacturing a pulp molded article according to the present embodiment, the pulp slurry concentration in the cavity at the initial stage of the formation of the pulp layer in the papermaking process is lower than the set supply concentration of the first pulp slurry. The initial stage of the formation of the pulp layer in the papermaking process means that the pulp supplied into the cavity is 0 to 30%, preferably 0 to 20% of the whole pulp required for forming the pulp molded article.
%.

In the method for manufacturing a pulp molded article according to the present embodiment, the pulp slurry concentration in the cavity at the initial stage of the formation of the pulp layer in the paper making process is lower than the set supply concentration of the first pulp slurry. In particular, when the set supply concentration of the first pulp slurry is 1% by weight or more, the pulp slurry concentration ρc ｛in the cavity at the initial stage of forming the pulp layer in the papermaking process = the amount of pulp in the cavity / (the amount of pulp in the cavity). The amount of water in the slurry + the amount of water in the diluting fluid) is from 16 to {2500 / (25 + 6 ρs)}% based on the set feed concentration of the first pulp slurry.
It is preferable that Where pulp slurry concentration ρ
The aforementioned {(1/4) ρs · Vc} is used as the injection amount Vw of the diluting fluid in the expression for the upper limit value of c. When the pulp slurry concentration ρc in the cavity is less than 16, the ratio of the maximum thickness to the minimum thickness (maximum thickness / minimum thickness) of the molded body is preferably 1.0 to 3.0. As a result, the thickness unevenness of the molded body becomes so severe that scorching occurs during drying, the drying efficiency is reduced, and the compressive strength of the obtained molded body is reduced. Also, ρc is ｛250
If it exceeds 0 / (25 + 6 ρs)｝%, the injection amount Vw of the diluting fluid becomes eight times or more the cavity volume Vc, and the time required for the papermaking process becomes longer.

When the first pulp slurry I is injected until the amount of slurry in the cavity 13 reaches a predetermined amount, suction and dehydration of the pulp slurry through the suction path 14 are started. As a result, the water in the low-concentration first pulp slurry is discharged to the outside of the papermaking mold 10, and at the same time, as shown in FIG.
As shown in (1), the pulp fiber is deposited on the inner surface of the cavity 13 (the inner surface of the papermaking net), and the first pulp layer 15 as the outermost layer is formed on the inner surface of the cavity 13. When the first pulp slurry I having a low concentration is pressurized to a predetermined pressure in the cavity 13 as described above, the suction path 1
The pulp fiber is uniformly deposited in the vertical direction on the inner surface of the cavity 13 by suppressing the natural sedimentation of the pulp fiber. Even during the suction of the slurry through the suction passage 14, the injection of the first pulp slurry I is continuously performed.
The slurry concentration in the cavity 13 gradually becomes higher than at the beginning of the molding of the molded body.

Next, a predetermined amount of the first pulp slurry I
After the completion of the injection, the valves V1 and V2 are operated so that only the second slurry can be supplied from the system B in FIG. Then, as shown in FIG. 2C, a second pulp slurry II having a different composition from the first pulp slurry I is injected into the cavity 13 from the upper opening of the papermaking mold 10 under pressure. As a result, a mixed slurry of the first pulp slurry and the second pulp slurry exists in the cavity 13. The pressure of the pressure injection of the second pulp slurry II can be substantially the same as the pressure of the pressure injection of the first pulp slurry I. Second pulp slurry II
, The pressurized state in the cavity 13 is maintained.

The set supply concentration of the second pulp slurry is not particularly limited as long as the composition is different from that of the first pulp slurry. %, Particularly preferably 0.5 to 3% by weight. If the amount is less than 0.1% by weight, uniform wall thickness cannot be obtained, resulting in molding failure. If the amount exceeds 6% by weight, the injection amount of the diluting fluid is increased to obtain the effect of diluting the pulp slurry in the cavity. Must be used, and the injection time is required accordingly. As the pulp fiber used in the second pulp slurry, a normal pulp fiber used in this type of pulp molded article can be used. In addition, by using pulp fibers described below, the obtained molded article can have characteristics as described below. In addition, the second pulp slurry is prepared by adding pulp fiber and water to inorganic substances such as talc and kaolinite, inorganic fibers such as glass fiber and carbon fiber, powder or fiber of thermoplastic synthetic resin such as polyolefin, non-wood or plant. It may contain components such as fiber and polysaccharide. The compounding amount of these components is preferably 1 to 70% by weight, particularly preferably 5 to 50% by weight based on the total amount of the pulp fiber and the components.

When the suction and dehydration in the cavity 13 through the suction passage 14 are continuously performed together with the pressure injection of the second pulp slurry, a mixed layer (not shown) of pulp composed of the components of the mixed slurry is formed. Is formed on the pulp layer 15. In this case, in the mixed slurry, the ratio of the second pulp slurry can be increased over time and continuously as compared with the ratio of the first pulp slurry.
In the mixed layer formed on the first pulp layer 15,
The composition continuously changes from the composition of the first pulp slurry to the composition of the second pulp slurry. Since the inside of the cavity 13 is under a pressurized state, the mixed layer is formed with a uniform thickness. In detail, by injecting each pulp slurry into the cavity 13 under pressure, even when forming a three-dimensional hollow molded body having a sharp rise from the bottom portion as in the present embodiment, the pulp slurry can be injected into the cavity 13. The pulp slurry is convected in the pulp slurry to exhibit a stirring action. Therefore, the pulp slurry concentration is made uniform in the vertical direction in the cavity 13, and the first pulp layer 15,
The thicknesses of the mixed layer 16 and the second pulp layer 17 are made uniform.

Next, the concentration of the pulp slurry in the cavity 13 at the final stage of the formation of the second pulp layer 17 in the paper making step is made lower than the set supply concentration of the supplied second pulp slurry. In particular, in the present embodiment, the pulp slurry in the cavity C when the water level in the cavity C falls is effectively reduced in the vertical direction at the final stage of the formation of the second pulp layer to make the thickness uniform. Is lower than the set feed concentration of the second pulp slurry.

In this embodiment, first, before the predetermined amount of the second pulp slurry II is injected under pressure, the fluid for dilution (fluid for dilution / stirring) can be supplied from the system C in FIG. V1 is operated to pressurize and inject the diluting fluid together with the second pulp slurry II, and the pulp slurry concentration in the cavity 13 at the final stage of the formation of the second pulp layer in the papermaking process is set and supplied to the second pulp slurry. Lower than the concentration. When a predetermined amount of pressurized injection of the second pulp slurry II is completed, V is supplied so that only the diluting fluid can be supplied from the system C.
1 is operated, and as shown in FIG.
Then, only the diluting fluid is continuously injected under pressure, so that the pulp slurry concentration in the cavity 13 at the end of the formation of the second pulp layer in the papermaking process is lower than the set supply concentration of the second pulp slurry. By the supply of the diluting fluid, the second pulp slurry remaining in the cavity 13 is diluted and stirred, and when the dehydration through the suction passage 14 is continuously performed, the components of the second pulp slurry are deposited on the mixed layer. The formed second pulp layer 17 as the innermost layer is formed uniformly. Also in this case, since the pulp slurry in the cavity 13 is diluted and stirred by the diluting fluid injected under pressure, the second pulp layer 17 is formed with a uniform thickness. Also, since the dilution fluid is injected under pressure, the suction path 14
Dewatering is also performed well, and the finish on the inner surface is also good. In the present embodiment, in particular, by injecting water, hot water, or the like as the diluting fluid under pressure, the second pulp slurry remaining in the pipe is also washed, so that when a new papermaking is started, Only the first pulp slurry can be supplied, and the second pulp can be prevented from being made on the outer surface of the molded body. The pressure injection of the diluting fluid may be performed after the injection of the second pulp slurry II is completed and while the second pulp slurry remains in the cavity.

In the method of manufacturing a pulp molded article of the present embodiment, the pulp slurry concentration in the cavity is adjusted to the second level at the end of the pulp layer formation in the paper making process.
Is lower than the set supply concentration of the pulp slurry. The term "final stage of the formation of the pulp layer in the papermaking process" means that the pulp supplied into the cavity is 70 to 100%, preferably 80 to 100% of the whole pulp required for forming the pulp molded article.
It means that it is at 100%.

In the method of manufacturing a pulp molded article according to the present embodiment, the pulp slurry concentration in the cavity at the final stage of the formation of the pulp layer in the papermaking process is 16 to 18% of the set supply concentration of the second pulp slurry. It is preferable that

The injection amount of the above-mentioned diluting fluid at the final stage of the formation of the pulp layer can be appropriately set according to the size and shape (cavity capacity) of the molded article to be molded and the set supply concentration of the second pulp slurry. When the set supply concentration of the second pulp slurry is 1% by weight or more, the injection amount Vw of the diluting fluid is (１ ／) ρs · Vc <Vw <8V
It is preferably c. If the injection amount Vw of the diluting fluid is (以下) ρs · Vc or less, the ratio of the maximum thickness to the minimum thickness (maximum thickness / minimum thickness) of the compact is a preferable range. As the thickness exceeds 0 to 3.0, the thickness unevenness of the molded article becomes so severe that burning occurs during drying, drying efficiency is reduced, and the compressive strength of the obtained molded article is reduced. Further, when the injection amount Vw of the diluting fluid is equal to or more than eight times the cavity volume Vc, the time required for the papermaking process becomes longer.

After a predetermined pulp layer is formed, paper injection is stopped and dehydration is performed. In the dehydration process,
First, as shown in FIG. 2 (e), the inside of the cavity 13 is suctioned and depressurized, and an elastic, expandable and contractible hollow core 18 is inserted into the cavity 13. The core 18 is inflated like a balloon in the cavity 13 to form a laminate composed of the first pulp layer 15, the mixed layer 16 and the second pulp layer 17 (hereinafter, referred to as a pulp laminate).
Is applied to the inner surface of the cavity 13 to give the inner surface shape of the cavity 13. Therefore, the core 18 is made of urethane, fluorine-based rubber, silicone-based rubber, elastomer, or the like which is excellent in tensile strength, rebound resilience, elasticity and the like.

Next, as shown in FIG.
A pressurized fluid is supplied to the inside to expand the core 18, and the expanded core 18 presses the pulp laminated body against the inner surface of the cavity 13. Then, the pulp laminate is pressed against the inner surface of the cavity 13 by the expanded core 18, and the inner surface shape of the cavity 13 is transferred to the pulp laminate, and dehydration further proceeds. As described above, the pulp laminate is placed in the cavity 1 from the inside of the cavity 13.
3, the shape of the inner surface of the cavity 13 is accurately transferred to the pulp laminate even if the shape of the inner surface of the cavity 13 is complicated. In addition, unlike the conventional pulp mold manufacturing method, since there is no need to use a bonding step, the obtained molded article does not have a seam or a thick portion due to bonding. As a result, the strength of the obtained molded body is increased and the appearance impression is improved. As the pressurized fluid used to expand the core 18, for example, compressed air (heated air), oil (heated oil), and other various liquids are used.
The pressure for supplying the pressurized fluid is 0.01 to 5MP.
a, particularly preferably 0.1 to 3 MPa.

When the shape of the inner surface of the cavity 13 is sufficiently transferred to the pulp laminate and the pulp laminate can be dehydrated to a predetermined moisture content, as shown in FIG. Pull out. Then, the core 18 automatically shrinks and returns to its original size. Next, the contracted core 18 is taken out of the cavity 13, and the papermaking mold 10 is further opened to take out the wet pulp laminate 19 having a predetermined moisture content.

Next, the pulp laminate 19 taken out is subjected to a heating and drying process. In the heating / drying step, the same operation as in the paper making step shown in FIG. 2 is performed except that the paper making / dewatering is not performed. That is, first, a dry mold in which a cavity having a shape corresponding to the outer shape of a molded body to be molded is formed by abutting a set of split molds is heated to a predetermined temperature, and the dry mold is wetted in the dry mold. The pulp laminate is loaded.

Next, a core similar to the core 18 used in the papermaking step was inserted into the pulp laminate, and a pressurized fluid was supplied into the core to expand the core. The pulp laminate is pressed against the inner surface of the cavity by the core. The material of the core and the supply pressure of the pressurized fluid can be the same as in the above-described papermaking process. In this state, the pulp laminate is heated and dried. The pulp laminate,
When the core is sufficiently dried, the pressurized fluid in the core is drained, and the core is contracted and taken out. Further, the drying mold is opened, and the molded article is taken out.

As described above, in the present embodiment, the diluting fluid is injected into the cavity at the initial stage and the final stage of molding of the molded product. Since the concentration of the pulp slurry in the inside is lower than the set supply concentration of the first or second pulp slurry, the natural sedimentation of solids in the slurry can be sufficiently suppressed, and thereby, there is no thickness unevenness in the vertical direction. A shaped body can be formed. In addition, since the first pulp slurry I and the second pulp slurry II are continuously injected into the cavity 13, a molded body having a multilayer structure in the thickness direction can be efficiently manufactured. In particular, when water is injected as a diluting fluid after the completion of the injection of the second pulp slurry, the second pulp slurry remains in the system D shown in FIG. And the papermaking process can be immediately advanced.

Further, the molded article 1 thus produced is
As shown in FIG. 2H, the diameter of the opening 2 is
Is a cylindrical bottle (hollow container) having a diameter smaller than the diameter of the container, and is particularly suitably used for accommodating contents such as powders and granules. The molded body 1 has no joint at any of the opening 2, the trunk 3, and the bottom 4, and the opening 2, the trunk 3
And the bottom 4 are integrally formed. Therefore, the strength of the molded body 1 is increased and the appearance impression is improved.

FIG. 3 shows the multilayer structure of the molded article produced according to the present embodiment. The first pulp layer 15 as the outermost layer and the second pulp layer 17 as the innermost layer have a multilayer structure. A mixed layer 16 is formed in which the composition continuously changes from the composition of the first pulp layer to the composition of the second pulp layer. As a result, the bonding strength between the first pulp layer 15 and the second pulp layer 17 is increased, and delamination between both layers is effectively prevented. In addition, the first pulp layer 15 and the second
The formation of the mixed layer 16 between the pulp layer 17 and the pulp layer 17 can be confirmed by microscopic observation of the cross section of the molded body.

The first pulp layer 15, the mixed layer 16, and the second
The thickness of each of the pulp layers 17 can be appropriately determined according to the use of the molded article and the like. In particular, the thickness of the outermost layer (the thickness of the first pulp layer 15 in the present embodiment) is 5 to 90%, preferably 10 to 70%, particularly 10 to 50% of the thickness of the entire molded product, When a pulp fiber having a low whiteness is used, it is preferable from the viewpoint that sufficient concealing properties can be seen from the outside, the inner layer is hardly exposed even if the outermost layer is damaged, and the inner layer has good coatability. The thickness of each layer is determined by the injection amount and concentration of the first and second pulp slurries at the time of production of the molded body.

Since the molded body manufactured according to the present embodiment has a multilayer structure, it is possible to individually impart a function to each layer. For example, only the first pulp layer 15 as the outermost layer can be used as a colored layer by blending a colorant such as a pigment or a dye or a colored Japanese paper or synthetic fiber only with the first pulp slurry. Incorporating a colorant only in the first pulp slurry means that a pulp having relatively low whiteness, for example, a pulp made from waste paper such as deinked pulp is blended in the slurry (for example, a whiteness of 60% or more). ,
(Especially 70% or more) because the color tone can be easily adjusted. The amount of the coloring agent is preferably 0.1 to 15% by weight of the amount of the pulp fiber.

Further, the first or second pulp slurry may be
Length-weighted average fiber length is 0.8-2.0mm, Canadian Standard Freeness is 100-600cc
In the frequency distribution of the fiber length, fibers having a fiber length of 0.4 mm or more and 1.4 mm or less occupy 20 to 90% of the whole, and fibers having a length of more than 1.4 mm and 30 mm or less constitute 5 to 50% of the whole. The thickness of the first pulp layer 15 or the second pulp layer 17 becomes extremely uniform by blending the pulp fiber occupying the above. Particularly, the first pulp slurry contains bleached pulp of hardwood (LBKP), has a length-weighted average fiber length of 0.2 to 1.0 mm, a Canadian standard freeness of 50 to 600 cc, and a frequency distribution of fiber length. In the case of using a pulp fiber in which fibers having a fiber length of 0.4 mm or more and 1.4 mm or less occupy 50 to 95% of the whole, the obtained molded article has a good surface smoothness and can be used for printing or printing. It is suitable for coating.

The length-weighted average fiber length is a value obtained by measuring the frequency distribution of the fiber length of the pulp fiber and calculating the length-weighted average. A KAJAANI FS-200 fiber length measuring device (manufactured by Valmet Automation Co., Ltd.) was used for the measurement, and the measurement conditions were a fiber count of 20,000 or more.

Further, by adding additives such as a water-resistant agent, a water-repellent agent, a moisture-proofing agent, a fixing agent, a fungicide, and an antistatic agent to the first pulp slurry, the first pulp layer 15 A function corresponding to the function of each additive can be provided. First pulp layer 1 as the outermost layer containing these additives
No. 5 preferably has a surface tension of 10 dyn / cm or less, and has a water repellency (JIS P 8137) of R
It is preferably 10. Furthermore, by mixing a thermoplastic synthetic resin powder or fiber with the first pulp slurry, the first pulp layer 15 can be provided with abrasion resistance and fuzziness can be suppressed. This degree of wear resistance is
It is preferably 3H or more as represented by pencil scratching strength (JIS K 5400).

As described above, in the present embodiment, when it is desired to develop a desired property using a predetermined additive or pulp fiber, the additive is applied only to a specific layer in which the property is most efficiently developed. And the like may be blended, so that there is an advantage that the blending amount of additives and the like can be reduced as compared with a single-layer pulp molded article.

The present invention is not limited to the embodiment described above. For example, in the above-described embodiment, the pulp slurry and the diluting fluid are supplied into the cavity by the system shown in FIG. 1, but each pulp slurry and the diluting fluid are supplied into the cavity by an independent system. You can also.

Further, the present invention is not limited to any means for lowering the concentration of the pulp slurry in the cavity at the beginning or end of the formation of the pulp layer in the papermaking step.
For example, a pulp slurry having a low concentration may be supplied in the initial stage of forming the pulp layer, and the pulp slurry may be switched to a pulp slurry having a normal concentration (set supply concentration) when a predetermined supply amount is reached. Further, at the end of the formation of the pulp layer, the pulp slurry having a normal concentration (set supply concentration) may be switched to a pulp slurry having a low concentration.

In the present invention, hot water can be used for the pulp slurry in order to increase the efficiency of suction and dewatering. When using warm water, 35 to 90 ° C, especially 45 ° C
It is preferable to use warm water at ~ 80 ° C.

The method for producing a pulp molded article of the present invention can also be applied to the production of a molded article having a single-layer structure or a three- or more-layer structure. For example, the present invention can be applied to the production of a molded product having a layer structure shown in FIG. 3, and as shown in FIG. 4A, the first pulp layer 17 shown in FIG.
Of the first pulp layer 15 ′ between the second pulp layer 17 and the first pulp layer 15 ′ based on the composition of the second pulp layer 17 Forming a mixed layer 16 ′ whose composition has been continuously changed to the composition,
The present invention can also be applied to the production of a molded article having a total layer structure of five layers in which the innermost layer and the outermost layer have the same composition. In this case, by forming the first pulp layers 15 and 15 ′ from pulp having high whiteness and the second pulp layer 17 from pulp having low whiteness such as waste paper, the whiteness on appearance is high. In addition, a low-cost molded product can be obtained. Or,
As shown in FIG. 4B, the second pulp layer 1 shown in FIG.
On the seventh side, the third pulp layer 2 having a different composition from any of the composition of the second pulp layer 17 and the first pulp layer 15
No. 1 is further formed between the second pulp layer 17 and the third pulp layer 21 and the third pulp layer 17
The mixed layer 20 in which the composition is continuously changed to the compounding composition of the pulp layer 21 may be formed to have a total of five layers. In this case, a multilayer molded body using various kinds of raw materials can be obtained. Even when a single-layer or three- or more-layer molded article is manufactured, the set supply concentration of the pulp slurry to be supplied into the cavity is 0.1 to 6% by weight, particularly 0.5 to 3%.
It is preferable to set the weight%. Also, after papermaking of the molded body,
A plastic layer, a coating layer, or the like may be provided on the outer surface and / or the inner surface to further increase the strength of the molded body, effectively prevent leakage of the contents, or perform decoration.

Further, a reinforcing member made of plastic or the like may be disposed at a portion where a load is applied when the molded body is used, for example, an opening or a bottom, so as to improve the durability of the molded body. Further, some of these parts may be formed of plastic or the like.

The present invention can also be applied to the production of a substantially rectangular parallelepiped carton-type container in which the cross-sectional shape of the opening and the cross-sectional shape of the body are substantially the same. In addition, the present invention can be applied to the manufacture of a molded article such as an object such as an ornament in addition to a hollow container used to store contents.

Further, two or more kinds of pulp slurries having different composition are sequentially injected into the cavity of the papermaking mold, and are sucked and dewatered through the suction passage of the papermaking mold, thereby forming each pulp without forming a mixed layer. A pulp layer composed of solid components of the slurry can be sequentially formed. Further, at the time of pulp slurry injection, only drainage by opening a drain valve may be performed, and suction and dehydration may be performed after the pulp slurry injection is completed. Further, instead of the dehydration using the core, aeration dehydration can be performed by supplying air, water vapor, or the like from the inside of the molded body.

Further, the present invention relates to a method for producing a papermaking mold by assembling a split mold having a suction path as in the above embodiment, and injecting pulp slurry from above into the cavity of the papermaking mold and supplying the slurry. Although preferred, the present invention can also be applied to a production method in which the papermaking mold is immersed in a pool filled with pulp slurry and the pulp slurry is supplied into the cavity of the papermaking mold. Also, a split mold papermaking mold having a suction path is arranged with its papermaking surface facing upward, and an outer frame surrounding at least the papermaking surface is arranged in the papermaking mold in a liquid-tight manner, and the papermaking surface and After a pool for filling the pulp slurry with the outer frame is formed, a predetermined amount of the pulp slurry is filled in the pool, and the pulp slurry is sucked through the suction passage to form a molded body on the papermaking surface. Can also be applied.

[0051]

EXAMPLES Using the papermaking mold and the supply system shown in FIG. 1, molded articles were prepared as in Examples 1 to 4 and Comparative Examples 1 and 2, and test pieces were cut out from the produced molded articles. The average thickness, the maximum thickness, the minimum thickness and the ratio thereof, and the compressive strength (maximum strength) of the test piece were examined. Table 1 shows the results. Table 1 also shows the injection amount and injection time of the diluting fluid (water) in each example and comparative example.

Example 1 Using a pulp slurry having the following composition, water was injected at the beginning and end of the pulp layer formation in the papermaking process according to the time chart shown in FIG. 5 to dilute the pulp slurry in the cavity. A molded body was manufactured. At the time of manufacturing the molded body, first, before injection of the pulp slurry, 1 liter (0.25 liter / second) of room temperature water (5-20 ° C. tap water; the same applies hereinafter) as a diluting fluid.
Was injected into the cavity (capacity: 1 liter), and then the pulp slurry was injected under pressure at a pressure of 0.1 MPa. next,
The inside of the cavity was suctioned and dehydrated through a suction path, and pulp was deposited on the papermaking surface. Then, after injecting 4.5 liters of pulp slurry, 1 liter of normal-temperature water (0.25 liter / second) was injected into the cavity as a diluting fluid. A core made of an elastic material was inserted into the pulp laminate obtained in this manner, air was injected into the core at a pressure of 0.3 MPa, and the pulp laminate was pressed against the inner surface of the cavity to perform further dehydration. Next, the papermaking mold was opened, and the pulp laminate was taken out and loaded into the drying mold. The drying mold has a cavity having the same shape as the papermaking mold. Then, a core made of an elastic material is inserted into the pulp laminate loaded in the drying mold, and air is injected into the core at a pressure of 1 MPa to press the pulp laminate against the inner surface of the cavity to form the drying mold. The pulp laminate was dried by heating to 220 ° C. When the pulp laminate was sufficiently dried, the drying mold was opened, and a bottle-shaped molded product was taken out. <Composition of pulp slurry> Liquid component: water Solid component: deinked waste paper (DIP) and NB having a weight ratio of 7: 3
KP mixed pulp Set supply concentration of pulp slurry: 1% by weight

Examples 2 to 4 Two-layer molded articles were produced in the same manner as in Example 1 except that the injection amount and injection time of water as a diluting fluid in the papermaking process were as shown in Table 1. .

Comparative Example 1 A molded body was prepared in the same manner as in Example 1 except that water was not injected and the pulp slurry was not diluted.

Comparative Example 2 A molded article was produced in the same manner as in Example 1 except that the amount and time of water as a diluting fluid in the papermaking process were as shown in Table 1.

[Evaluation of Unevenness of Thickness] The thickness of eight predetermined walls in the height direction of the peripheral wall portion (excluding the thread portion) of the upright molded body was measured with a micrometer, and the maximum thickness and the minimum thickness were measured. And their ratio and average thickness.

[Measurement of Compressive Strength] After a cylindrical part having a thread on the outer peripheral surface was driven into the mouth of the obtained bottle-shaped molded body, the powder was manufactured by Kao Corporation under the trade name “Powder A cap with a cap filled with 79 g of “Wide Height” was screwed onto the part, and the part was loaded into a compression strength measuring machine (RTA-500, manufactured by Orientec Co., Ltd.), and the crosshead speed was increased to 20 mm / min. The measurement was performed by setting.

[0058]

[Table 1]

As is clear from the results shown in Table 1, the molded articles (products of the present invention) produced according to Examples 1 to 4 had uneven thickness in the vertical direction as compared with the molded articles of Comparative Examples 1 and 2. Was small, and the compression strength was also excellent.

[0060]

According to the present invention, it is possible to efficiently manufacture a pulp molded article in which thickness unevenness in the vertical direction is suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a papermaking mold and a pulp slurry supply system used in a papermaking process of a method for producing a molded article of the present invention.

2 (a) to 2 (g) are schematic process diagrams of an embodiment of the method for producing a pulp molded article of the present invention,
FIG. 2H is a schematic diagram of the obtained pulp molded article.

FIG. 3 is a schematic view showing a multilayer structure of a molded article manufactured according to the present invention.

FIG. 4 is a schematic diagram (corresponding to FIG. 3) showing another embodiment of the multilayer structure of the molded article manufactured according to the present invention.

FIG. 5 is a diagram schematically showing a time chart of a paper making process in an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulp molded product 2 Opening 3 Body 4 Bottom 10 Papermaking mold 14: Suction path

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[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]

Wherein said pulp slurry is fed into the cavity, a two or more pulp slurry having a different blend composition, according to claim supplies other pulp slurry after the start of the supply of one pulp slurry 1 or 3. The method for producing a pulp molded article according to 2 .

5. assembling the split mold having a suction path and the paper type, after supplying <br/> the path Rupusurari to該抄paper type in the cavity,該抄paper by sucking the pulp slurry through the suction passage In the method for producing a pulp molded article provided with a papermaking step of forming a pulp layer on an inner surface of a mold, the pulp slurry supplied into the cavity is at least two kinds of pulp slurries having different composition. After the supply of the pulp slurry starts, another pulp slurry is supplied, and at least after the supply of the last pulp slurry into the cavity is completed, the pulp slurry is supplied to the cavity.
A method for producing a pulp molded article, which supplies the last pulp slurry dilution / stirring fluid into the cavity while remaining in the cavity.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

The present invention has been made based on the above findings.
And a split mold with a suction path is assembled into a papermaking mold,
After supplying the path Rupusurari to該抄paper type in the cavity, in the manufacturing method of the pulp molded article having a paper making step of forming a pulp layer on the inner surface of該抄paper type by sucking the pulp slurry through the suction passage, The cavity
After the supply of the pulp slurry into the pulp
While the slurry remains in the cavity, the cavity
Supplying a fluid for the pulp slurry diluted into I, by providing a method for producing a pulp molded article to lower the concentration of the pulp slurry in the cavity in the form Narutsui phase of the pulp layer in the paper making process The above object has been achieved.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006] The present invention is directed to paper type by assembling split mold provided with a suction path, after supplying the path Rupusurari to該抄paper type in the cavity,該抄paper by sucking the pulp slurry through the suction passage In the method for producing a pulp molded article provided with a papermaking step of forming a pulp layer on an inner surface of a mold, the pulp slurry supplied into the cavity is at least two kinds of pulp slurries having different composition. After the supply of the pulp slurry starts, another pulp slurry is supplied, and at least after the supply of the last pulp slurry into the cavity is completed, the pulp slurry is
The above object has been achieved by providing a method for producing a pulp molded article in which the last pulp slurry dilution / stirring fluid is supplied into the cavity while remaining in the cavity.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

In the method for manufacturing a pulp molded article according to the present embodiment, the pulp slurry concentration in the cavity at the initial stage of the formation of the pulp layer in the paper making process is lower than the set supply concentration of the first pulp slurry. In particular, when the set supply concentration of the first pulp slurry is 1% by weight or more, the pulp slurry concentration ρc ｛in the cavity at the initial stage of forming the pulp layer in the papermaking process = the amount of pulp in the cavity / (the amount of pulp in the cavity). The amount of water in the slurry + the amount of water in the diluting fluid) is from 16 to {2500 / (25 + 6 ρs)}% based on the set feed concentration of the first pulp slurry.
It is preferable that Where pulp slurry concentration ρ
The aforementioned {(1/4) ρs · Vc} is used as the injection amount Vw of the diluting fluid in the expression for the upper limit value of c. When the pulp slurry concentration ρc in the cavity is less than 16 % , the ratio of the maximum thickness to the minimum thickness (maximum thickness / minimum thickness) of the molded product is preferably in the range of 1.0 to 3.0. , And the thickness unevenness of the molded body becomes so severe that burning occurs during drying, drying efficiency is reduced, and the compressive strength of the obtained molded body is reduced. Also, ρc is ｛25
When the ratio exceeds 00 / (25 + 6 ρs)｝%, the injection amount Vw of the diluting fluid becomes eight times or more the cavity volume Vc, and the time required for the papermaking process becomes longer.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction contents]

[0051]

EXAMPLES Using the papermaking mold and the supply system shown in FIG. 1, molded articles were prepared as in the following Examples 1 to 4 and Comparative Example 1 , and a test piece was cut out from the formed molded article. Were examined for average thickness, maximum thickness, minimum thickness and their ratio, as well as compressive strength (maximum strength). Table 1 shows the results. Table 1 also shows the injection amount and injection time of the diluting fluid (water) in each example and comparative example.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0052

[Correction method] Change

[Correction contents]

Example 1 Using a pulp slurry having the following composition, water was injected at the beginning and end of the pulp layer formation in the papermaking process according to the time chart shown in FIG. 5 to dilute the pulp slurry in the cavity. A molded body was manufactured. At the time of producing the molded body, first, before injection of the pulp slurry, room temperature water (5-20 ° C. tap water; the same applies hereinafter) as a diluting fluid 0.5 liter (0.25 liter /
Seconds) into the cavity (1 liter capacity)
The pulp slurry was injected under pressure at a pressure of 0.1 MPa. Next, the inside of the cavity was suctioned and dehydrated through a suction path, and pulp was deposited on the papermaking surface. After injecting 4.5 liters of pulp slurry, 0.5 ml of room temperature water was used as a diluting fluid.
One liter (0.25 liter / second) was injected into the cavity. A core made of an elastic material is inserted into the pulp laminate obtained in this manner, and air is applied to the core at a pressure of 0.3 MPa.
a, and the pulp laminate was pressed against the inner surface of the cavity to further perform dehydration. Next, the papermaking mold was opened, and the pulp laminate was taken out and loaded into the drying mold. The drying mold has a cavity having the same shape as the papermaking mold. Then, a core made of an elastic material is inserted into the pulp laminate loaded in the drying mold, and air is injected into the core at a pressure of 1 MPa to press the pulp laminate against the inner surface of the cavity to form the drying mold. The pulp laminate was dried by heating to 220 ° C. When the pulp laminate was sufficiently dried, the drying mold was opened, and a bottle-shaped molded product was taken out. <Composition of pulp slurry> Liquid component: water Solid component: deinked waste paper (DIP) and NB having a weight ratio of 7: 3
KP mixed pulp Set supply concentration of pulp slurry: 1% by weight

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0053

[Correction method] Change

[Correction contents]

[0053] except that the Example 2-4] injection volume and the injection time of the water as a diluting fluid in the paper making process was as shown in Table 1, it was made work in the same manner as in Example 1.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0055

[Correction method] Deleted

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0058

[Correction method] Change

[Correction contents]

[0058]

[Table 1]

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0059

[Correction method] Change

[Correction contents]

As is clear from the results shown in Table 1, the molded articles (products of the present invention) produced in Examples 1 to 4 were comparative examples.
Compared to the first molding body, small vertical unevenness of thickness,
It was also confirmed that the composition had excellent compressive strength.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenichi Otani 2606 Kabane-cho, Akaga-cho, Haga-gun, Tochigi Prefecture Inside Kao Corporation Research Institute 72) Inventor Shingo Odashima 2606 Akabane, Kaga-cho, Haga-gun, Tochigi Prefecture F-term in Kao Corporation Research Laboratories (reference) 3E033 AA01 BA10 BB08 DB01 DD01 FA10 4L055 AA02 AC06 AC09 BF08 EA03 FA22 FA23 GA05

Claims (4)

[Claims] 1. A split mold having a suction path is assembled to form a papermaking mold. After the supply of a pulp slurry having a predetermined supply concentration into a cavity of the papermaking mold is started, the pulp slurry is sucked through the suction path. And forming a pulp layer on the inner surface of the papermaking mold by a method for producing a pulp molded article, wherein the concentration of the pulp slurry in the cavity at the initial or / and final stage of the formation of the pulp layer in the papermaking step A method for producing a pulp molded article in which the pulp slurry supplied is lower than the set supply concentration. 2. The method for producing a pulp molded article according to claim 1, wherein a fluid for diluting the pulp slurry is supplied into the cavity at least before the supply of the pulp slurry is started into the cavity and / or after the supply is completed. . 3. The pulp slurry supplied into the cavity is two or more pulp slurries having different composition, and another pulp slurry is supplied after starting supply of one pulp slurry. 3. The method for producing a pulp molded article according to 2. 4. A papermaking mold is assembled by assembling a split mold having a suction path, and after starting supply of a pulp slurry having a predetermined set supply concentration into a cavity of the papermaking mold, the pulp slurry is sucked through the suction path. And forming a pulp layer on the inner surface of the papermaking mold, wherein the pulp slurry supplied into the cavity is a mixture of two or more pulp slurries having different composition. Then, after the supply of one pulp slurry is started, another pulp slurry is supplied, and at least after the supply of the last pulp slurry into the cavity is completed, the final pulp slurry dilution / stirring fluid is introduced into the cavity. A method for producing a pulp molded article to be supplied.