JP7435276B2 - Pulp molded body - Google Patents

Description

The present invention relates to a pulp molded article.

In recent years, in view of the growing awareness of environmental issues related to the increase in waste, etc., pulp molds, which are made from pulp and molded from pulp slurry using a wet suction molding method, are being used as various packaging materials instead of plastic containers and metal containers. Molded objects are attracting attention. Pulp molded bodies are packaging materials that contribute to environmental conservation, contributing to resource and energy conservation, and have excellent recyclability when disposed of, making them suitable for incineration even if discarded.

Patent Document 1 discloses a single-layer structure that is made from a single raw material composition and has a density distribution in the thickness direction, with the aim of providing a novel pulp molded product that is thin, lightweight, and has excellent heat insulation performance. A pulp molded article is described, which comprises a pulp fiber layer, and at least the inner or outer surface of the pulp fiber layer is covered with a coating layer.

Japanese Patent Application Publication No. 2007-291600

In conventional pulp molded articles, when slits, through holes, etc. were provided, there was a problem in that the portions of the provided slits or holes became fluffy. Further, there was a problem that it was not suitable for surface processing such as lamination.
An object of the present invention is to provide a pulp molded article that is suppressed from fluffing at the slit or through-hole portions and has excellent surface processing suitability.

As a result of intensive studies, the inventors of the present invention have found that the above problem can be solved by setting the density of the pulp molded product within a specific range and furthermore, by configuring the pulp molded product from a specific pulp. .
That is, the present invention relates to the following <1> to <9>.
<1> A pulp molded product having at least one of a slit and a through hole in at least a part of the region, a density of 0.45 g/cm ³ or more, and meeting at least one of the following requirements 1 and 2. A pulp molded body that satisfies the needs.
Requirement 1: The pulp that makes up the pulp molded product is a mixed pulp of non-wood pulp and wood pulp.Requirement 2: The Canadian standard freeness of the pulp that makes up the pulp molded product is 100 mL or more and 650 mL or less. 2> The pulp molded article according to <1>, which satisfies Requirements 1 and 2.
<3> The pulp molded article according to <1> or <2>, which has a thickness of 0.4 mm or more and 3.0 mm or less.
<4> The pulp constituting the pulp molded article contains non-wood pulp, and the non-wood pulp contains at least one selected from bagasse and bamboo according to any one of <1> to <3>. Pulp molded body.
<5> The pulp constituting the pulp molded body is a mixed pulp of non-wood pulp and wood pulp, and the content of the non-wood pulp in the mixed pulp is 20% by mass or more and 80% by mass or less, < The pulp molded article according to any one of 1> to <4>.
<6> The pulp molded article according to any one of <1> to <5>, wherein at least one of the slit and the through hole is formed by laser processing.
<7> A secondary processed pulp molded product obtained by surface-processing the pulp molded product according to any one of <1> to <6>.
<8> The secondary processed pulp molded article according to <7>, wherein the surface treatment is performed by at least one surface treatment method of a direct printing method, a lamination method, a transfer method, and a vapor deposition method.
<9> The secondary processed pulp molded article according to <7> or <8>, wherein the surface treatment is performed by at least one surface treatment method of a vacuum lamination method and a hot stamp transfer method.

According to the present invention, it is possible to provide a pulp molded article in which fluffing around the slits or through holes is suppressed when the slits or through holes are provided, and which has excellent suitability for surface processing.
In addition, in the following description, "fuzzing around the slit or through hole is suppressed when a slit or through hole is provided" is also referred to as "excellent drilling characteristics."

FIG. 1 is a perspective view of a pulp mold lid produced in an example.

[Pulp molded body]
The pulp molded article of the present invention is a pulp molded article having at least one of a slit and a through hole in at least a partial region, has a density of 0.45 g/cm ³ or more, and meets the following requirements 1. At least one of 2 is satisfied.
Requirement 1: The pulp constituting the pulp molded product (hereinafter also referred to as "raw material pulp") is a mixed pulp of wood pulp and non-wood pulp.Requirement 2: The pulp constituting the pulp molded product (raw material pulp) The pulp molded article of the present invention, which has a Canadian standard freeness of 100 mL or more and 650 mL or less, has excellent drilling properties and surface workability. The detailed reason why the above effect is obtained is unknown, but it is thought that by setting the density to a certain value or more, fluffing in the slits and through-holes is suppressed when slits and through-holes are provided. Furthermore, in addition to specifying the density, the pulp constituting the pulp molded article may be a mixed pulp with non-wood pulp, and/or a pulp with a Canadian standard freeness within a specific range. Thus, a pulp molded product having excellent surface workability such as lamination property can be obtained.

<Raw material pulp>
In the present invention, the pulp (raw material pulp) constituting the pulp molded product satisfies at least one of the above requirements 1 and 2, and preferably satisfies both requirements 1 and 2.
[Requirement 1: The raw material pulp is a mixed pulp of wood pulp and non-wood pulp]
When the raw material pulp satisfies Requirement 1, the raw material pulp is a mixed pulp of wood pulp and non-wood pulp. Note that when only requirement 2 is satisfied, the raw material pulp may be only wood pulp or only non-wood pulp, and is not particularly limited, but preferably a mixed pulp of wood pulp and non-wood pulp.

Examples of wood pulp include wood pulp that is generally used for paper manufacturing, and depending on its preparation method, chemical pulp such as kraft pulp (KP), sulfite pulp (SP), soda pulp (AP); Semi-chemical pulp such as chemical pulp (SCP) and chemical ground wood pulp (CGP); Mechanical pulp such as ground wood pulp (GP), thermomechanical pulp (TMP, BCTMP), refiner ground wood pulp (RGP); Waste paper pulp; etc. are categorized.
Examples of wood pulp include softwood pulp and hardwood pulp depending on the raw material. Examples of softwood pulp include pulps obtained from Abies, Pinus, and the like. Further, examples of the hardwood pulp include pulps obtained from the genus Acacia, genus Eucalyptus, genus Asus (for example, poplar), and the like.
Among these, softwood kraft pulp (NKP) and hardwood kraft pulp (LKP) are preferable as the wood pulp.

In the present invention, the raw material pulp preferably contains hardwood pulp, and more preferably hardwood kraft pulp. As the hardwood pulp, at least one hardwood pulp of the genus Acacia and the genus Eucalyptus is preferred. By containing hardwood pulp, a pulp molded product with better surface processability such as lamination properties can be obtained.
The content of hardwood pulp in the raw material pulp is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 25% by mass, from the viewpoint of further improving the drilling properties and surface workability of the pulp molded product. More preferably, it is 40% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less.

In the present invention, the raw material pulp may contain softwood pulp. As the softwood pulp, softwood kraft pulp is preferred. By containing softwood pulp, a pulp molded article with even greater strength can be obtained.
As the coniferous pulp, coniferous pulp of the genus Pinus is preferable, and radiata pine is more preferable.

When the raw material pulp satisfies Requirement 1, the content of wood pulp including softwood pulp and hardwood pulp in the raw material pulp is preferably 5% by mass from the viewpoint of further improving the drilling properties and surface workability of the pulp molded product. The above is more preferably 10% by mass or more, still more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 45% by mass or more, and preferably 95% by mass or less, more preferably It is 90% by mass or less, more preferably 80% by mass or less, even more preferably 55% by mass or less.

Non-wood pulp is fiber obtained from the skin, stems, leaves, and leaf sheaths of plants. Specifically, pulps obtained from cotton linters, cotton, linen, hemp, ramie, straw, esparto, manila hemp, xyzal hemp, jute, flax, kenaf, bamboo, bagasse, ganpi, mitsumata, kozo, and mulberry are used. Can be mentioned.
The non-wood pulp preferably contains at least one selected from bagasse and bamboo pulp, and more preferably contains at least one selected from bagasse and bamboo, from the viewpoint of improving the drilling properties of the pulp molded body. Preferably, bagasse is more preferable. Bagasse is the residue after squeezing the raw sugar solution from sugar cane, and there is a possibility that it will be disposed of as waste unused, so bagasse is preferable from the viewpoint of reducing environmental burden.

When requirement 1 is satisfied, the content of non-wood pulp in the raw material pulp is preferably 20% by mass or more, more preferably 25% by mass or more, from the viewpoint of further improving the surface smoothness and oil resistance of the pulp molded product. , more preferably 35% by mass or more, even more preferably 45% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, still more preferably 70% by mass or less, even more preferably 65% by mass or less. It is not more than 60% by mass, more preferably not more than 60% by mass.

In the present invention, waste paper such as waste paper or corrugated waste paper (waste cardboard) may be used as the pulp raw material in both cases where the raw material pulp satisfies Requirement 1 and Requirement 2. When waste paper is used as a material, the fibers of the waste paper are fluffed and deformed, so the surface properties tend to be poor and the punching properties tend to be poor. From the viewpoint of improving the perforation properties, surface workability, and surface design of the pulp molded product, the content of waste paper in the raw material pulp is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably is 3% by mass or less, and it is even more preferable not to use it.

[Requirement 2: The Canadian standard freeness of the raw material pulp is 100 mL or more and 650 mL or less]
In the present invention, when the raw material pulp satisfies requirement 2, the Canadian standard freeness of the raw material pulp is 100 mL or more, preferably 150 mL, from the viewpoint of the productivity of the pulp raw material and the paper formability when producing the pulp molded product. As mentioned above, it is more preferably 200 mL or more, and from the viewpoint of surface workability, it is 650 mL or less, preferably 600 mL or less, more preferably 500 mL or less, and still more preferably 450 mL or less.
The degree of beating may be adjusted so that the Canadian standard freeness is within the above range.
Canadian Standard Freeness is measured in accordance with JIS P 8121-2:2012.

<Other ingredients>
The pulp molded body is formed using the above-mentioned pulp as a main raw material. The pulp molded body may be formed from 100% pulp, but in addition to pulp, other materials such as various internal additives can be added.
Internal additives include inorganic substances such as talc and kaolin, inorganic fibers such as glass fiber and carbon fiber, powders or fibers of synthetic resins such as polyolefin, polysaccharides such as carboxymethyl cellulose, sizing agents, wet paper strength agents, and oil resistance. Examples include colorants such as additives, retention agents, drainage improvers, bulking agents, sulfuric acid, pH adjusters, pitch control agents, slime control agents, and pigments. Among these, it is preferable to contain a sizing agent.

Sizing agents include rosin-based sizing agents (for example, acidic rosin-based sizing agents, neutral rosin-based sizing agents), alkyl ketene dimers, alkenyl succinic anhydrides, and styrene-containing polymers such as styrene-(meth)acrylate copolymers. and alkyl ketene dimers are preferred.

Wet paper strength agents for internal addition include polyamide amine/epichlorohydrin resin, epoxidized polyamide polyamine, dialdehyde starch, urea formaldehyde resin, melamine-formaldehyde, polyacrylamide, methylolated Examples include polyacrylamide and polyethyleneimine.
In addition, water repellents include wax emulsions, metal soaps (alkali salts of sodium, potassium, zinc, lithium, magnesium, etc.), fatty acid chromium complex salts (myristic salt complexes, stearic acid chromic chloride complex salts, etc.), zirconium water repellents, silicone An example is an emulsion.
The pulp molded article of the present invention contains non-wood pulp, and since it is possible to improve oil resistance and water resistance using only the pulp raw material, it is possible to improve the oil resistance and water resistance using only the pulp raw material. It is possible to obtain sufficient oil resistance even if the amount of addition is reduced or even if it is not added. Note that, for the purpose of obtaining higher oil resistance and water resistance, a mode in which a wet paper strength enhancer, a water repellent agent, or an oil resistance agent is added is not excluded.

<Density>
The pulp molded article of the present invention has a density of 0.45 g/cm ³ or more. When the density is within the above range, a pulp molded product with excellent punching properties can be obtained.
The density of the pulp molded product is preferably 0.50 g/cm ³ or more, more preferably 0.60 g/cm ³ or more, from the viewpoint of further improving the drilling properties, and from the viewpoint of ease of manufacturing the pulp mold. , preferably 1.2 g/cm ³ or less, more preferably 1.0 g/cm ³ or less, even more preferably 0.95 g/cm ³ or less.
The density of the pulp molded product can be measured according to JIS P 8118:2014. Note that JIS P 8118:2014 is a method used for paper and paperboard, and in the present invention, there may be cases where the sample size cannot be taken as specified, and in that case, the sample size may be adjusted appropriately and used for measurement. . If the molded object does not have a flat part, select the part closest to the flat part and use it for measurement. The basis weight is measured according to JIS P 8124:2011, and the sample size is adjusted as described above. A flat part of the molded body is used for measurement.

<Thickness>
From the viewpoint of providing slits and/or through holes in at least a portion of the pulp molded product of the present invention, the thickness of the pulp molded product in the portion where the slits and/or through holes are provided is preferably is 0.3 mm or more, more preferably 0.5 mm or more, even more preferably 0.8 mm or more, even more preferably 1.0 mm or more, and preferably 3.0 mm or less, more preferably 2.0 mm or less, More preferably, it is 1.5 mm or less.
The thickness of the pulp molded product can be measured according to JIS P 8118:2014.

<Drilling>
The pulp molded article of the present invention has at least one of a slit and a through hole in at least a partial region.
Methods for providing slits and through holes are not particularly limited, but examples include punching and laser processing, and among these, laser processing is preferred.
Note that the slit is a cut or slit passing through the pulp mold formed body, and may be a straight line, a curve, an L-shape, an x mark, etc., and its length etc. are not particularly limited.
In addition, examples of the planar shape of the through hole include a circular shape and a polygonal shape. The term "circular" is not limited to a perfect circle, but includes an ellipse. Polygons include shapes surrounded by three or more line segments, such as triangles, quadrilaterals, and pentagons. Further, in addition to polygons and circles, the shape may be any shape such as a semicircle, a rounded rectangle, or a crescent shape.
For example, when the pulp molded product is used as a lid for a cup, a slit for a straw insertion port, or a through hole for a drinking spout or an air hole may be provided. Illustrated.

<Secondary processed pulp molded body>
The pulp molded product of the present invention may be surface-treated to form a secondary processed pulp molded product. In the present invention, the secondary processed pulp molded product is a pulp molded product subjected to surface treatment. In addition, since the pulp molded article of the present invention has excellent surface smoothness, it also has the advantage that surface processing can be easily performed. The secondary processing may be performed after providing at least one of the slits and the through holes, or the secondary processing may be performed and at least one of the slits and the through holes are provided, and is not particularly limited.
The secondary processing method is not particularly limited as long as it is possible to process the surface of the pulp mold, but the secondary processing pulp molded product can be produced by direct printing, lamination, transfer, and vapor deposition. It is preferable that the surface be treated by at least one surface treatment method according to the method, and more preferably the surface treated by at least one surface treatment method of direct printing method, lamination method, and transfer method. It is more preferable that the surface be treated by at least one of a lamination method and a transfer method.
Note that the method is not limited to these methods, and a pre-printed sticker or the like may be attached.

(Direct printing method)
The direct printing method is a method in which ink or resin is applied directly to the surface of the pulp molded product for the purpose of imparting colors, patterns, patterns, etc., as well as waterproofness and moisture resistance. , a method of surface-processing a pulp molded body.
For printing, any printing means such as letterpress printing using a rubber plate or resin plate, silk screen printing, pad printing, electrostatic printing, thermal transfer printing, etc. may be used. By printing, designs, characters, etc. can be provided on the surface of the obtained pulp molded product.
Alternatively, it may be printed directly onto the pulp molded body by brushing, spraying, or the like. Among these, spray coating is preferred from the viewpoint of uniformly applying the resin and the like. Spray application may be performed by air spray, airless spray, electrostatic spray, or the like.
When imparting waterproof/moisture-proof properties to the surface of a pulp molded product, acrylic resins, styrene resins, urethane resins, melamine resins, olefin resins, epoxy resins, polyvinyl alcohol resins, and vinylidene chloride resins can be used. A water-based emulsion paint containing resin such as resin in the solid content, an aqueous solution paint of these resins, an organic solvent-based paint, etc. may be applied.

(Lamination method)
The lamination process is preferably performed by covering with a resin film, and examples of the resin film used include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, Polyamide resins such as nylon, polyvinyl resins such as polyvinyl chloride, styrene resins such as polystyrene, ethylene/vinyl alcohol copolymers, thermoplastic resin films such as polyacrylonitrile, modified polyethylene terephthalate, aliphatic polyesters, etc. Examples include degradable resin films. In consideration of manufacturing cost, moldability, etc., polyolefin resins are preferred, and in terms of environmentally friendly disposal, biodegradable resin films are preferred. The lamination process may be performed by laminating two or more of these resin films.
Although the thickness of the resin film is not particularly limited, it is preferably 10 μm or more and 300 μm or less.

By laminating the above-described resin film, functions such as water resistance, oil resistance, and gas barrier properties can be improved or imparted.
In addition, a pattern may be printed in advance on the resin film to be laminated, or colored pigments, fine particles (pearl pigments, holograms, etc.), luminous dyes, luminous pigments, etc. may be added. By using such a resin film, gloss and design can be imparted to the surface of the pulp molded product.

The lamination process may be performed on the pulp molded article by a known method such as extrusion lamination, thermal lamination, dry lamination, or wet lamination.
Among these, thermal lamination is preferred, vacuum lamination and vacuum press are preferred, and vacuum lamination is more preferred.
Vacuum lamination may be performed by deforming the sheet placed on top of the substrate by suction from the base material side (pulp mold side), or by dividing the upper and lower chambers, which have been evacuated in advance, into two with a resin film. Alternatively, the upper chamber equipped with a resin film heating device may be pressurized, and the resin film may be laminated onto a base material (pulp molded product) placed in the lower chamber.
In addition, a vacuum press deforms silicone rubber, etc. into the shape of the base material by vacuum suction from the base material (pulp molded product) side, and in some cases, applies pneumatic force from above, and creates a space between the silicone rubber, etc. and the base material. The sandwiched resin film is laminated to the base material by the pressure of silicone rubber.
Alternatively, the resin film may be preformed using a mold according to the shape of the pulp molded product, and then laminated with the pulp molded product.

The lamination process may be performed by a conventionally known method, and examples of the vacuum lamination device include a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd.).
In addition, conditions such as temperature and pressure during lamination may be appropriately selected depending on the material and thickness of the resin film to be laminated, the shape of the base material, the presence or absence of adhesive, etc. Lamination is carried out at 200°C.

During lamination, an adhesive may or may not be applied between the resin film and the pulp molded product. As the adhesive, polyurethane adhesive, polyacrylic adhesive, polyester adhesive, epoxy adhesive, polyvinyl acetate adhesive, cellulose adhesive, and other laminating adhesives can be used. . When applying an adhesive, a coloring pigment, a pearl pigment, fine particles (such as a hologram), a luminous pigment, a luminous dye, etc. may be added to the adhesive.

(Transfer method)
Examples of the transfer method include various transfer methods such as a hot stamp transfer method, an in-mold transfer method, and a water pressure transfer method, and either a dry transfer method or a wet transfer method may be used. Further, in the in-mold transfer method, a preforming step may be added.
Among the transfer methods, a hot stamp transfer method (hereinafter also simply referred to as a "hot stamp method") is preferred. The hot stamping method uses a film called "foil" on which metal is vapor-deposited or pigment is coated, and the film is thermally transferred to a base material via a thermal adhesive layer provided on the surface of the foil. The foil used in the hot stamping method is laminated in the following order: a base film with release properties (for example, biaxially oriented polyester film), a release layer (protective layer), a pattern layer/evaporation layer, and a thermal adhesive layer. If necessary, a release layer is provided between the base film and the protective layer. Hot stamping methods include (i) up-down method and (ii) roll transfer method, which use the principle that the pattern layer and vapor deposition layer in the area where heat and pressure are applied are transferred to the base material (pulp molded product). are the same. In the up-down method, a template with a built-in heater is pressed against the base material from the base film side, and the pattern layer and vapor deposition layer are transferred to the base material via the thermal adhesive layer. Similarly, in the roll transfer method, a heated roller is pressed from the base film side to transfer the pattern layer and vapor deposition layer onto the base material. Furthermore, by subjecting the base film to grinding, gloss treatment, unevenness processing, etc., it is also possible to shape (impart unevenness) on the pattern layer and vapor deposited layer during transfer.

(vapor deposition)
Vapor deposition may be performed by a conventionally known vapor deposition method, and may be either physical vapor deposition or chemical vapor deposition. Although not particularly limited, vapor deposition is preferably performed for the purpose of imparting metallic luster to the pulp molded product, and vacuum vapor deposition, which is physical vapor deposition, is preferred. Vapor deposition is more preferred.
As the deposition material, it is preferable to use metals such as aluminum, chromium, zinc, gold, silver, platinum, and nickel, and oxides and fluorides such as SiO ₂ , TiO ₂ , ZrO ₂ , and MgF ₂ .
The thickness of the vapor deposited layer is not particularly limited, but is preferably 0.1 μm or more.

[Method for manufacturing pulp molded body]
Although the method for producing the pulp molded article is not particularly limited, it is preferable to produce it by a production method having the following steps 1 to 3 in this order.
Step 1: A pulp suspension preparation step for preparing a pulp suspension. Step 2: A papermaking step in which pulp is made from the pulp suspension through a papermaking mold. Step 3: The pulp obtained after the above papermaking step. Hot pressing step of heating the mold intermediate and hot pressing it with a first press mold and a second press mold located in the opposite direction to the first press mold. Step 4: Obtained pulp mold Step of providing at least one of a slit and a through hole in the molded body In step 1, a pulp suspension (pulp slurry) is prepared by adding other additives such as a pulp raw material and a sizing agent. The concentration of the suspension (slurry concentration) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.0% by mass, from the viewpoint of surface smoothness, dimensional stability, and productivity. .5% by mass or more, and preferably 7% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less.

Step 2 is a papermaking process in which pulp is produced from the pulp suspension through a papermaking die.
A forming mold such as a wire mesh mold with a vacuum-drawn water-permeable structure is immersed in the pulp suspension, and the pulp suspension is sucked into the forming mold and the water is discharged. At the same time, the pulp fibers are laminated and adsorbed onto the mold. A three-dimensional wet paper paper symmetrical to the mold is formed, and then the mold is lifted out of the pulp suspension, and the water-containing three-dimensional wet paper paper is dehydrated by suction or pressure.
At this time, while continuing vacuum suction, the mold with the pulp layered and adsorbed on the mold surface is approached with a mold (releasing device) applied with vacuum suction, facing the pulp suction surface. After the intermediate is dehydrated by compressed vacuum suction, the vacuum pressure of the molding die is reduced to zero, and the mold is pulled back and released with the pulp mold intermediate adsorbed to the mold.

Step 3 is to heat the mold intermediate obtained after the papermaking step using a first press mold and a second press mold located in the opposite direction to the first press mold. This is a hot pressing process.
In step 3, the dehydrated pulp mold intermediate obtained in step 2 is transferred to, for example, a first press mold for hot pressing consisting of a porous mold. The pulp mold intermediate transferred to the first press mold is located in a direction opposite to the first press mold and is engaged with the first press mold. A predetermined pulp molded product is obtained by heating and pressurizing with a second press mold for hot pressing.

In step 3 (hot pressing step), the pressure during pressing by the first press mold and the second press mold is preferably 0.1 MPa·s from the viewpoint of obtaining a pulp molded product with excellent surface smoothness. The above is more preferably 0.3 MPa or more, still more preferably 0.4 MPa/s or more, even more preferably 0.6 MPa or more, and preferably 3.0 MPa/s or less from the viewpoint of power consumption and device load. , more preferably 2.0 MPa or less, still more preferably 1.5 MPa·s or less.

In step 3 (hot pressing step), the temperature during hot pressing is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 170°C or higher, from the viewpoint of obtaining a pulp molded product with excellent surface smoothness. From the viewpoint of power consumption, device load, and suppression of discoloration, the temperature is preferably 280°C or lower, more preferably 250°C or lower, and even more preferably 230°C or lower.

The pulp molded product obtained as described above is further cut off at unnecessary parts, and in step 4, at least one of a slit and a through hole is provided. Methods for providing the slits and through holes are not particularly limited, but examples include punching and laser processing, as described above, and among these, laser processing is preferred.

The pulp molded product of this embodiment is a molded product with excellent smoothness called a fine mold, and is suitable for use as a packaging material for foods, medical products, electronic parts, etc. by taking advantage of its excellent surface workability and drilling properties. be able to. In addition, it has excellent surface smoothness and can be easily processed by printing, coating, laminating, etc. on the surface, and even when slits, through holes, etc. are provided, fuzzing is suppressed, so it is not limited to the above applications. It can also be widely applied to accessory cases, cup lids, ornaments, etc.

EXAMPLES The features of the present invention will be explained in more detail below with reference to Examples and Comparative Examples. The materials, usage amounts, proportions, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. Note that "parts" and "%" in Examples and Comparative Examples refer to "parts by mass" and "% by mass," respectively, unless otherwise specified.

Example 1
For a mixed pulp slurry of 50 parts of eucalyptus pulp, which is a hardwood pulp, and 50 parts of bamboo pulp, which is a non-wood pulp (Canadian standard freeness (CSF) of mixed pulp: 660 mL), AKD was added as a sizing agent in terms of solid content. (alkyl ketene dimer, manufactured by Seiko PMC Co., Ltd.) was added in an amount of 0.8% by mass, and after stirring, the slurry concentration was adjusted to 0.7% by mass. A papermaking mold with a metal mesh attached to the surface was submerged in the slurry, vacuum was drawn from inside the mold, and the pulp slurry was sucked onto the mesh to form a three-dimensional wet paper. The wet paper was transferred to a dehydration mold, dehydrated under pressure of 0.7 MPa, then transferred to a mold heated to 180°C, and further dried under pressure of 1.2 MPa. After cutting off the excess portion, the notches shown in FIG. 1 were made to obtain the pulp mold lid shown in FIG. The size (diameter) of the pulp mold lid was approximately 75 mm. The thickness and density of the pulp molded body (pulp mold lid) are shown in the table.

Example 2
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 1 except that the Canadian standard freeness (CSF) was changed to 510 mL.

Example 3
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 2 except that bagasse was used instead of bamboo.

Example 4
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 3 except that the Canadian standard freeness (CSF) was changed to 400 mL.

Example 5
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 3 except that the Canadian standard freeness (CSF) was changed to 320 mL.

Example 6
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 3 except that the Canadian standard freeness (CSF) was changed to 180 mL.

Example 7
For a mixed pulp slurry of 50 parts of acacia pulp, which is a hardwood pulp, and 50 parts of bagasse pulp, which is a non-wood pulp (Canadian standard freeness (CSF) of mixed pulp: 510 mL), AKD (AKD) was added as a sizing agent in terms of solid content. 0.8% by mass of alkyl ketene dimer (manufactured by Seiko PMC Co., Ltd.) was added, and after stirring, the slurry concentration was adjusted to 0.7% by mass. Using this slurry, a pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 1.

Example 8
Added 0.8% by mass of AKD (alkyl ketene dimer, manufactured by Seiko PMC Co., Ltd.) as a sizing agent in terms of solid content to eucalyptus pulp (Canadian Standard Freeness (CSF): 510mL), which is a hardwood pulp. After stirring, the slurry concentration was adjusted to 0.7% by mass. Using this slurry, a pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 1.

Example 9
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 8 except that the pulp raw material, eucalyptus, was replaced with bamboo.

Example 10
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 8 except that the pulp raw material, eucalyptus, was changed to radiata pine (NBKP).

Examples 11, 12, 13
A pulp mold lid having the shape shown in FIG. 1 was produced using the same formulation as in Example 4 by adjusting the dehydration and heating pressures and changing the density.

Example 14
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 4 except that the pulp raw material was changed to eucalyptus (LBKP)/bagasse = 20/80 (mass ratio).

Example 15
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 4 except that the pulp raw material was changed to eucalyptus (LBKP)/bagasse = 80/20 (mass ratio).

Example 16
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 3 except that the pulp raw material was changed to eucalyptus (LBKP)/bagasse = 20/80 (mass ratio).

Example 17
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 3 except that the pulp raw material was changed to eucalyptus (LBKP)/bagasse = 80/20 (mass ratio).

Examples 18, 19, 20
A pulp mold lid having the shape shown in FIG. 1 was produced in the same manner as in Example 4 except that the thickness was changed.

Comparative example 1
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 8 except that the Canadian standard freeness (CSF) of the pulp slurry was changed to 660 mL.

Comparative example 2
A pulp mold lid having the shape shown in FIG. 1 was obtained in the same manner as in Example 9 except that the Canadian standard freeness (CSF) of the pulp slurry was changed to 660 mL.

Comparative example 3
A pulp mold lid having the shape shown in FIG. 1 was produced using the same formulation as in Example 3, except that the dehydration and heating pressures were adjusted to change the density.

The pulp molded bodies obtained in Examples and Comparative Examples were evaluated as follows.
(Suitability for lamination)
Five pulp mold lids produced in each example and comparative example were prepared and left for 24 hours in an environment compliant with ISO 187:1990 (temperature 23 ± 1°C, relative humidity 50 ± 2%). Temperature and humidity were controlled. In the above environment, a flat part (25 mm x 25 mm square) in the center of the lid was cut out, and ABOX laminate film 100 μm was laminated thereon using an ABOX laminator A4 compatible laminating machine. After 2 hours of lamination, the square portion was cut out, the laminated film was peeled off, and evaluated.
5: Good adhesion between the film and the mold, making it difficult to peel off.
4: Good adhesion between the film and the mold, making it a little difficult to peel off.
3: The adhesion between the film and the mold is good, but it is easy to peel off.
2: The part that is not adhered to the film and mold can be seen slightly and is easy to peel off.
1: The parts that are not adhered to the film and mold can be confirmed and easily removed.
The numbers in the table are the average values of five (decimal points are rounded off).

(through hole)
Five pulp mold lids produced in each example and comparative example were prepared and left for 24 hours in an environment compliant with ISO 187:1990 (temperature 23 ± 1°C, relative humidity 50 ± 2%). After controlling the temperature and humidity, the holes shown in the figure were punched using a powerful punch "No. 200" (manufactured by Plus Co., Ltd.).
4: The area around the hole was very clean.
3: There is slight fluff around the hole, but it is not noticeable visually.
2: There is a little fluff around the hole, but it is not particularly noticeable.
1: There is fluff around the hole, which is a concern.
The numbers in the table are the average values of five (decimal points are rounded off).

In addition, in the examples, those with no evaluation of "1" in any evaluation and whose total evaluation was 5 or more were considered to have passed.

(thickness and density)
Measurement was performed according to JIS P 8118:2014.

From the results of Examples and Comparative Examples, the pulp molded product of the present invention, which has a density of 0.45 g/cm ³ or more and satisfies the above-mentioned requirements 1 or 2, is a good pulp raw material for a pulp molded product. It was shown that it has lamination suitability, excellent surface workability, and excellent drilling properties.
In particular, the results of Examples 3 to 6 showed that even with the same pulp composition, surface workability was further improved by reducing the Canadian standard freeness. This is considered to be because the surface smoothness of the resulting pulp molded product was improved by advancing the beating of the pulp.
On the other hand, as for the type of pulp raw material, as in Examples 8 and 9, surface workability was improved when hardwood pulp and non-wood pulp were used together, compared to when hardwood pulp and non-wood pulp were used alone. A pulp molded product with excellent balance of drilling properties was obtained. In addition, by changing the mixing ratio of hardwood pulp and non-wood pulp, increasing the amount of hardwood pulp improves the surface workability, but tends to decrease the drilling properties; While this was an improvement, surface workability tended to decrease.
Additionally, there was a tendency for hole identification to improve as the density was increased.

Example 2-1
A PET film (polyethylene terephthalate film, manufactured by Toray Industries, Inc., film thickness = 70 μm ) was laminated, and then a secondary processed pulp mold lid having the notches shown in FIG. 1 was obtained.
As a result, fuzzing was suppressed when through-holes were provided, and water resistance was improved.

Example 2-2
A PP film (polyethylene terephthalate film, Toray Industries, Ltd. Co., Ltd., film thickness = 100 μm) was laminated thereon, and then a secondary processed pulp mold lid provided with the notches shown in FIG. 1 was obtained.
As a result, the printed pattern was clear and glossy, and the decorativeness was improved. Additionally, by laminating a resin film on the outside of the pulp mold lid, the surface performance in terms of scratch resistance and stain resistance has been improved.

The pulp molded article of the present invention has excellent surface workability and perforation properties, and is expected to be applied to various uses including packaging materials for foods and the like.

Claims (11)

A pulp molded article having at least one of a slit and a through hole in at least a partial region,
The pulp constituting the pulp molded body contains hardwood pulp, and the content of hardwood pulp in the pulp constituting the pulp molded body is 10% by mass or more and 90% by mass or less,
A pulp molded article having a density of 0.45 g/cm ³ or more and satisfying at least one of the following requirements 1 and 2.
Requirement 1: The pulp that makes up the pulp molded product is a mixed pulp of non-wood pulp and wood pulp.Requirement 2: The Canadian standard freeness of the pulp that makes up the pulp molded product is 100 mL or more and 650 mL or less. The pulp molded article according to claim 1, which satisfies requirements 1 and 2. The pulp molded article according to claim 1 or 2, having a thickness of 0.4 mm or more and 3.0 mm or less. The pulp molded product according to any one of claims 1 to 3, wherein the pulp constituting the pulp molded product contains non-wood pulp, and the non-wood pulp contains at least one selected from bagasse and bamboo. . The pulp constituting the pulp molded body is a mixed pulp of non-wood pulp and wood pulp, and the content of the non-wood pulp in the mixed pulp is 20% by mass or more and 80% by mass or less. 4. The pulp molded article according to any one of 4. The pulp constituting the pulp molded body is a mixed pulp of non-wood pulp and wood pulp, and the content of the non-wood pulp in the mixed pulp is 35% by mass or more and 80% by mass or less. 5. The pulp molded article according to any one of 5. The density is 0.60g/cm ³ The pulp molded article according to any one of claims 1 to 6, which is the above. The pulp molded article according to any one of claims 1 to 7 , wherein at least one of the slit and the through hole is formed by laser processing. A secondary processed pulp molded product obtained by surface-processing the pulp molded product according to any one of claims 1 to 8 . The secondary processed pulp molded article according to claim 9 , wherein the surface treatment is performed by at least one surface treatment method of a direct printing method, a lamination method, a transfer method, and a vapor deposition method. The secondary processed pulp molded article according to claim 9 or 10 , wherein the surface treatment is performed by at least one surface treatment method of a vacuum lamination method and a hot stamp transfer method.