JP2022172841A - Base paper for deep drawing and deep-drawn product - Google Patents

Abstract

To provide a base paper for deep drawing that has low environmental load, has high extensibility, prevents cracking in the paper surface during deep drawing, and has high shape reproducibility, and a deep-drawn product including the same.SOLUTION: Base paper for deep drawing has a paper substrate layer composed of a paper substrate. The constituent pulp of the paper substrate has a length-weighted mean fiber length of 0.60 mm or more and 2.40 mm or less. Out of Young's moduli of the base paper in the longitudinal direction and the transverse direction, the greater one is defined as A and the smaller one is defined as B, where A is 2,600 N/mm2 or less and the ratio C of Young's moduli represented by the formula (1): C=A/B is 1.00 or more and 1.80 or less. The base paper has elongations at break of 3.0% or more in the longitudinal direction and the transverse direction, respectively, and the geometric mean of the elongations at break in the longitudinal direction and the transverse direction is 4.0% or more.SELECTED DRAWING: None

Description

The present invention relates to a base paper for deep drawing processing and a deep drawn product.

Conventionally, plastic containers have been used in large quantities as food containers or packaging materials for various industrial products because they are easy to mold, can be mass-produced, and can be manufactured at low cost. As these plastic containers, for example, expanded polystyrene containers obtained by molding expanded polystyrene beads or press-molded expanded polystyrene sheets, polypropylene containers, polyethylene terephthalate containers, polyvinyl chloride containers and the like are widely used. However, the plastic container as described above has a problem that it imposes a heavy burden on the environment at the time of disposal. In other words, if it is landfilled, it will remain in the ground without being decomposed semi-permanently, and if it is incinerated, it will easily damage the incinerator due to its high combustion calorie, and it will be difficult to burn completely. However, there are problems such as the possibility of generating highly corrosive hydrogen chloride gas.

Therefore, in recent years, considering environmental issues, recycling issues, and resource saving, we have developed a plastic container that can be recycled, burns less calories when discarded, has biodegradability, and is environmentally friendly. There is a demand for a container made of low load pulp.

Pulp molded containers have conventionally existed as three-dimensional molded articles made of pulp or materials mainly composed of pulp. Pulp mold containers have long been widely used as packaging containers. However, it takes a long time to manufacture the pulp mold, and there is a problem in productivity. Furthermore, it has been difficult to impart sufficient water resistance and oil resistance to the pulp mold container, which is often required for food tray containers.

In addition to the pulp mold, a method of press-molding a pulp-based substrate sheet such as paperboard under heating is known as a method for obtaining a pulp-based molded article. In this method, a base material sheet with ruled lines in advance is loaded between the male and female molds, and press molding is performed by hot pressing. Such a press molding method has very high productivity because a molded product can be obtained by pressing once. However, unlike resins and metals, base sheets mainly composed of paper pulp generally lack stretchability, extensibility, and stretchability. Therefore, if deep press molding is performed to form a tray having a certain depth, the base sheet may break due to being unable to withstand the stretching. As a result, when ordinary paperboard or the like is used as a base material, it is possible to produce only a molded container with almost no depth, which is called a so-called paper plate, and the shape of the obtained molded product is very limited.

In order to solve such problems, for example, in Patent Document 1, a mixed solution of starch and an alkylketene dimer is applied to the surfaces of the surface layer and the back layer of a base paper for molded containers made of two or more layers. A molded container base paper is described.

JP 2014-167192 A

The base paper for molded containers described in Patent Document 1 uses a coating layer containing alkyl ketene dimer (AKD) on the surface to improve extensibility. However, when alkyl ketene dimer (AKD) is used on the surface of the paper base material, there is a problem that the adhesion between the paper base material and the laminate film is lowered and the laminate film is peeled off.

The present invention provides a base paper for deep drawing processing, which has low environmental load, high extensibility, is less likely to crack on the paper surface when deep drawing is performed, and has high shape reproducibility of the mold, and a base paper using the same The object is to provide a deep-drawn molded product.

The present inventors set the length-weighted average fiber length of the pulp constituting the base paper for deep drawing processing to a specific range, and set the maximum value of the Young's modulus in the longitudinal direction and the Young's modulus in the transverse direction of the base paper to a specific value or less. And the ratio is set to a specific range, and the breaking elongation in the machine direction and the transverse direction, and the geometric mean of the breaking elongation in the machine direction and the transverse direction are set to specific ranges, the above problems are solved. I found out.
That is, the present invention relates to the following <1> to <6>.
<1> A base paper for deep drawing processing, the base paper comprising a paper base layer made of a paper base,
The length-weighted average fiber length of the pulp constituting the paper base material is 0.60 mm or more and 2.40 mm or less, and the Young's modulus of the base paper is the Young's modulus of the longitudinal direction or the Young's modulus of the transverse direction, whichever is greater. is A, and the smaller Young's modulus is B, A is 2,600 N/mm ² or less, and the Young's modulus ratio C represented by the following formula (1) is 1.00 or more and 1.80 and
C=A/B (1)
A base paper for deep-drawing processing, wherein the breaking elongation in the machine direction and the transverse direction of the base paper is 3.0% or more, respectively, and the geometric mean of the breaking elongation in the machine direction and the transverse direction is 4.0% or more. .
<2> The base paper for deep drawing processing according to <1>, wherein the Young's modulus ratio C is 1.00 or more and 1.50 or less.
<3> The base paper for deep drawing processing according to <1> or <2>, wherein the curl value of the pulp constituting the paper base material is 7% or more and 12% or less.
<4> The base paper has a basis weight of 100 g/m ² or more and 500 g/m ² or less, a paper thickness of 0.10 mm or more and 0.90 mm or less, and a density of 0.60 g/cm ³ or more and 1.2 g. /cm ³ or less, the base paper for deep drawing processing according to any one of <1> to <3>.
<5> The base paper for deep drawing processing according to any one of <1> to <4>, further comprising a thermoplastic resin layer on at least one surface of the paper base layer.
<6> A deep drawn product using the base paper for deep drawing processing according to any one of <1> to <5>.

INDUSTRIAL APPLICABILITY According to the present invention, a base paper for deep-drawing processing, which has a low environmental load, high extensibility, is less likely to crack on the paper surface when deep-drawing is performed, and has high shape reproducibility, and a deep-drawing base paper using the same. A drawn article is provided. In addition, "high shape reproducibility" or "excellent shape reproducibility" means that the shape of the obtained molded product and the shape of the mold at the time of molding are highly similar, and the desired It means that a molded article close to the shape is obtained.

It is a schematic diagram of the deep-drawing forming process by press. It is the top view and front view of the molded article produced in the Example.

[Base paper for deep drawing]
The base paper for deep drawing processing of the present embodiment (hereinafter also simply referred to as "base paper") includes a paper base layer made of a paper base, and the length-weighted average fiber length of the pulp constituting the paper base is It is 0.60 mm or more and 2.40 mm or less, and when A is the larger Young's modulus of the Young's modulus in the longitudinal direction and the Young's modulus in the transverse direction of the base paper, and B is the Young's modulus of the smaller one, A is 2,600 N/mm ² or less, the Young's modulus ratio C represented by the following formula (1) is 1.00 or more and 1.80 or less, and the breaking elongation of the base paper in the longitudinal direction and the transverse direction is , each of which is 3.0% or more, and the geometric mean of the elongation at break in the machine direction and the transverse direction is 4.0% or more.
C=A/B (1)
According to the base paper for deep drawing processing of the present embodiment, the environmental load is low, the extensibility is high, cracks are less likely to occur on the paper surface when deep drawing is performed, and the shape reproducibility is high. Original paper is provided.
By using the base paper for deep drawing processing of the present embodiment, which has a paper base layer mainly composed of pulp, to obtain a deep drawn product, the environmental load can be reduced compared to conventional plastic containers.
In addition, the reason why cracks are less likely to occur on the surface of the paper substrate and the shape reproducibility is high during deep drawing is considered as follows. Since the paper base material is a non-uniform sheet in which pulp fibers are aggregated, there are many inter-fiber bonds that are difficult to crack during deep drawing, and there are few inter-fiber bonds that break during deep drawing. However, it is mixed with places where cracks are likely to occur. It is believed that by setting the length-weighted average fiber length of the pulp constituting the paper substrate layer within a specific range, both the strength of the paper substrate and the suppression of cracking during deep drawing are achieved.
In addition, of the Young's modulus in the longitudinal direction and the Young's modulus in the transverse direction of the base paper, the larger Young's modulus is set to a specific value or less, and the above-mentioned Young's modulus ratio C is set to 1.00 or more and 1.80 or less. As a result, the paper base material has moderate flexibility, which suppresses the occurrence of cracks during deep drawing, improves mold followability during molding, and provides excellent shape reproducibility. it is conceivable that.
Furthermore, by setting the breaking elongation in the machine direction and the transverse direction of the base paper, and the geometric mean of the breaking elongation in the machine direction and the transverse direction, to a specific value or more, the generation of cracks on the paper base surface during deep drawing is prevented. It is considered to be further suppressed. In deep drawing, it is necessary to suppress the occurrence of cracks on the paper substrate surface due to stretching in a short time. On the other hand, in measuring elongation at break, the base paper is broken more slowly than in deep drawing. Therefore, using base paper with excellent elongation at break does not necessarily prevent cracking of the paper surface during deep drawing, but base paper that does not meet the above requirements for elongation at break does not provide sufficient formability. can't
Note that deep drawing is a molding method for obtaining a three-dimensional molded product from a single sheet without processing such as cutting or bonding. Examples of deep draw forming include press forming, vacuum forming, and pressure forming.
The present invention will be described in more detail below.

A base paper for deep drawing processing comprises a paper substrate layer comprising a paper substrate. The base paper for deep-drawing processing has at least one paper base layer, and may have two or more paper base layers. Among these, it is preferable to have 1 to 5 layers of paper base layers, and it is more preferable to have 1 to 3 layers of paper base layers. Examples of embodiments having two or more paper base layers include polysand paper (paper base/polyethylene film/paper base) in which a polyethylene film is sandwiched between two paper base layers, and polyethylene film with three layers of paper base layers. is exemplified by polysand paper (paper base/polyethylene film/paper base/polyethylene film/paper base).
A thermoplastic resin layer may be further provided on one side or both sides of the paper substrate or polysand paper. That is, the base paper for deep drawing processing may be composed only of the paper base layer, but in addition to the paper base layer, it further has a thermoplastic resin layer on at least one surface of the paper base layer. is preferred. The thermoplastic resin layer preferably has a thermoplastic resin layer at least on the food contact surface when the product is formed into a deep-drawn product. A thermoplastic resin layer may also be provided on the surface opposite to the food contact surface.

[Paper base layer]
The paper base layer consists of a paper base, and the paper base contains pulp as a raw material. The manufacturing method and type of pulp are not particularly limited <Raw material pulp>
In the present embodiment, the pulp constituting the paper base material is preferably natural pulp fibers from the viewpoint of reducing the environmental load, and the natural pulp fibers include wood fibers (chemical pulp, mechanical pulp), non-wood fibers, and waste paper pulp. etc. are used arbitrarily as necessary. Examples of chemical pulp among wood fibers include kraft pulp using caustic soda and sodium sulfide when wood chips are digested, and sulfite pulp using sulfurous acid and hydrogen sulfite. These pulps may be unbleached or bleached (bleached). Mechanical pulps include groundwood pulp (GP) obtained by grinding logs with a grinder, refiner groundwood pulp (RGP) obtained by grinding (refining) waste wood from sawmills with a refiner, and lumber. Examples include thermomechanical pulp (TMP) obtained by heating and refining chips.
Among these wood fiber pulps, long fiber pulps obtained from conifers such as pine, larch, cedar, fir, and cypress are preferably used to improve the stretchability and strength of the paper substrate. In addition, short-fiber pulp obtained from broad-leaved trees such as eucalyptus, acacia, birch, beech, maple, elm, and chestnut can be used in combination, as long as the effects of the present invention are not impaired.

In addition, non-wood fibers that can be used in the present embodiment include bast fibers such as paper mulberry, mitsumata, gampi, flax, taima, kenaf, choma, jute, sunhemp, seed hair fibers such as cotton and cotton linter, Examples include leaf fibers such as Manila hemp, sisal hemp, and esparto, and stem fibers such as bamboo, rice straw, barley straw, and sugarcane bagasse. In particular, paper mulberry, mitsumata, kenaf, manila hemp, sisal hemp, cotton, and cotton linters have long fiber lengths and can improve the stretchability and strength of the base paper of the present embodiment, and are therefore preferably used. Cooking of non-wood fibers can be carried out in the same manner as for wood fibers.
Used paper pulp that can be used in the present embodiment includes used cardboard paper, used magazine paper, and the like.

These pulp fibers can be used alone or in combination of two or more. In addition, synthetic resin fibers can be mixed as necessary within a range that does not impair the effects of the present invention. Examples of usable synthetic resin fibers include polyethylene fibers, polypropylene fibers, polyamide fibers, polyethylene terephthalate fibers, polybutylene terephthalate fibers, and polylactic acid fibers.

In the present embodiment, from the viewpoint of obtaining the desired length-weighted average fiber length described later, it is preferable that the raw material pulp contains softwood pulp, and it is also preferable to use only softwood pulp. It is also preferable to use together.

<Pulp characteristics>
(length weighted average fiber length)
The length-weighted average fiber length of the pulp constituting the paper substrate is 0.60 mm or more, preferably 0.70 mm or more, more preferably 0.80 mm or more, from the viewpoint of obtaining paper strength as base paper, and Although the upper limit is not particularly limited, practically 2.40 mm or less is realistic.
The length-weighted average fiber length of the fibers constituting the paper substrate is obtained by defiberizing the base paper by the method described in the Examples, and measuring the fiber length of the obtained pulp slurry with a fiber length measuring instrument (for example, Valmet, model FS-5 with UHD base unit) and calculated.
The length-weighted average fiber length is calculated with respect to the fiber length measured by selecting fibers having a length of 0.2 mm or more and 7.6 mm or less.

(Number ratio of fine fibers)
In the pulp constituting the paper substrate, the number ratio of fine fibers having a fiber length of 0.2 mm or less is preferably 8% or more, more preferably 9% or more, still more preferably 10% or more, and even more preferably 12%. and is preferably 35% or less, more preferably 32% or less, even more preferably 30% or less, even more preferably 28% or less, and even more preferably 26% or less.
When the number ratio of the fine fibers is within the above range, the presence of the fine fibers increases the bonding between the fibers and further suppresses the occurrence of cracks and the like during deep drawing, which is preferable. It is also preferable because it suppresses a decrease in elongation at break due to an increase in fine fibers.
The number of fine fibers having a fiber length of 0.2 mm or less in the pulp of the fibers constituting the paper base material is obtained by defiberizing the base paper by the method described in Examples and measuring the fiber length of the obtained pulp slurry. It is measured and calculated with a device (for example, model FS-5, manufactured by Valmet, with a UHD base unit). Fibers having a fiber length of 0.2 mm or less and a fiber width of 75 μm or less are defined as fine fibers, and the ratio of the number of fine fibers to the measured number of pulp is calculated.

In order to make the length-weighted average fiber length and the number ratio of fine fibers of the pulp constituting the paper base material within the above ranges, the selection of the raw material pulp, the presence or absence of filtration in the chemical treatment and mechanical treatment of the pulp, It may be appropriately adjusted by selecting the concentration of the beating treatment, the beating load, and the like.
Moreover, powdered pulp obtained by mechanically pulverizing pulp fibers may be added for the purpose of increasing the number ratio of fine fibers.
Furthermore, when manufacturing the paper substrate, by adding a cationic polymer retention improver in the papermaking process, the proportion of fine fibers remaining in the paper substrate during papermaking increases. The number ratio of fine fibers may be increased by adding a cationic polymer.

(curl value)
The curl value of the pulp that constitutes the paper substrate is preferably 5% or more, more preferably 5.5% or more, and still more preferably 5% or more, from the viewpoint of increasing interfiber bonding and keeping the elongation at break of the base paper within the desired range. is 6% or more, more preferably 6.5% or more, particularly preferably 7% or more, and preferably 12% or less, more preferably 11% or less, and even more preferably 10% or less.
The curl value (also referred to as the curl index) of the pulp constituting the paper base material is the length of the fiber when the pulp fiber is straightened (L ₁ ) and the length of the fiber when it is curled (L ₂ ), it is shown as follows.
Curl value (%) = (L ₁ - L ₂ )/L ₁ × 100
Here, the fiber length (L ₁ ) and the fiber length (L ₂ ) are relative to the length of the fiber measured by selecting a fiber with _a length of 0.2 mm or more and 7.6 mm or less. , to calculate the length-weighted average. The length-weighted average fiber length described above is the length-weighted _average fiber length of L1.
L ₁ and L ₂ are calculated by image processing. _In L1, image processing is performed so that the length of the fiber is maximized, and in L2, image processing is performed so that the length is maximized in a curled ₍ bent) state.
The curl value tends to increase as the concentration of the pulp slurry during beating increases. Therefore, the curl value of the pulp constituting the base paper can be adjusted by adjusting the concentration of the pulp slurry during beating.
The curl value of the pulp constituting the paper base material is obtained by defiberizing the base paper by the method described in the Examples, and measuring the curl value of the obtained pulp slurry with a fiber length measuring instrument (for example, model FS-5, manufactured by Valmet Co., Ltd.). (with UHD base unit) and calculated.

(Canadian standard freeness)
The Canadian Standard Freeness (CSF), which is measured in accordance with JIS P 8121-2:2012, of the pulp that makes up the paper base suppresses the occurrence of cracks during molding and improves shape reproducibility during molding. From the viewpoint of improvement, it is preferably 200 mL or more, more preferably 400 mL or more, still more preferably 600 mL or more, and preferably 800 mL or less, more preferably 750 mL or less, still more preferably 700 mL or less.

<Optional component>
The paper substrate may optionally contain, for example, anionic, cationic, nonionic or amphoteric retention agents, drainage improvers, dry strength agents, wet strength agents, fillers, sizing agents, etc. Optional components such as internal additives, dyes, and fluorescent brighteners may also be included.
Dry paper strength agents include cationized starch, polyacrylamide, carboxymethylcellulose and the like. The content of the dry paper strength agent is not particularly limited, and the amount used may be appropriately adjusted according to the characteristics of the pulp to be used, the papermaking method, and the like.
Wet strength agents include polyamide polyamine epichlorohydrin, urea formaldehyde resins, melamine formaldehyde resins and the like.
Fillers include inorganic materials such as talc, kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, alumina, magnesium carbonate, magnesium oxide, silica, white carbon, bentonite, zeolite, sericite, and smectite. Organic fillers such as fillers, acrylic resins and vinylidene chloride resins can be mentioned.
Examples of sizing agents include rosin sizing agents, synthetic sizing agents, internal sizing agents such as petroleum resin-based sizing agents, and surface sizing agents such as styrene/acrylic acid copolymers and styrene/methacrylic acid copolymers.

<Method for producing paper substrate>
The method for producing a paper substrate preferably includes a step of making paper from a slurry containing the raw material pulp.
The papermaking method is not particularly limited, and examples thereof include an acidic papermaking method in which papermaking is performed at a pH of about 4.5, a neutral papermaking method in which papermaking is performed at a pH of about 6 to about 9, and the like.
In the papermaking process, chemicals for the papermaking process, such as pH adjusters, antifoaming agents, pitch control agents, and slime control agents, can be added as appropriate.
The paper machine is also not particularly limited, and examples thereof include a continuous paper machine such as a fourdrinier type, a cylinder type, and an inclined type, or a multi-layer paper machine combining these.

In the present embodiment, in the papermaking process, the jet/wire ratio (J/W ratio), which is the ratio of the flow speed (J) of the stock jetted onto the wire and the running speed (W) of the papermaking wire, is From the viewpoint of keeping the above-described Young's modulus ratio C within a desired range, the value is preferably close to 1.0, preferably 0.95 or more, more preferably 0.98 or more, and still more preferably 1.00 or more. and is preferably 1.08 or less, more preferably 1.05 or less, still more preferably 1.02 or less.

(Clupak processing)
The paper substrate may be Clupak-treated. The Clupak treatment is a treatment that imparts elongation performance by finely shrinking paper on a paper machine.
The specific manufacturing method is to install a Clupak device in a part of the paper machine dryer, pass the wet paper between an endless thick elastic rubber blanket with a nip roll and a heating dryer, and the pre-stretched blanket shrinks. Then, the running paper web is shrunk, and the elongation at break is increased. In addition, the resulting shrinkage is dried and fixed so that it will not stretch in the post-process.
In the Clupak machine, the longitudinal breaking elongation of paper can be adjusted mainly by the ratio of the production speed on the entry side of the Clupak machine and the production speed on the exit side of the Clupak machine.

<Characteristics of paper substrate>
The paper substrate may be single-layer paper or multi-layer paper, preferably single-layer paper or more and seven-layer paper or less, more preferably single-layer paper or more. 5 layers or less.
Also, as the paper substrate, multi-layered paper in which two or more paper layers are laminated with an adhesive may be used.
The total thickness of the paper base layer is preferably 50 μm or more, more preferably 60 μm or more, still more preferably 80 μm or more, and is preferably 500 μm or less, more preferably 450 μm or less, further preferably 400 μm or less, Even more preferably, it is 350 μm or less.
The total thickness of the paper base layer is the total thickness when the base paper for deep drawing processing has two or more paper base layers, for example, when using polysand paper. be.
The thickness of the paper substrate is measured according to JIS P 8118:2014.

The total basis weight of the paper substrate is preferably 30 g/m ² or more, more preferably 50 g/m ² or more, still more preferably 100 g/m ² or more, still more preferably 150 g/m ² or more, and particularly preferably is 180 g/m ² or more, and is preferably 500 g/m ² or less, more preferably 400 g/m ² or less, even more preferably 350 g/m ² or less, still more preferably 300 g/m ² or less.
The basis weight of the paper substrate is measured according to JIS P 8124:2011.

The total density of the paper substrate is preferably 0.4 g/cm ³ or more, more preferably 0.5 g/cm ³ or more, still more preferably 0.6 g/cm ³ or more, and even more preferably 0.65 g. /cm ³ or more, and preferably 1.2 g/cm ³ or less, more preferably 1.1 g/cm ³ or less, and even more preferably 1.0 g/cm ³ or less.
When the paper base material is Clupak-treated, the density of the paper base material is preferably 0.4 g/cm ³ or more, more preferably 0.5 g/cm ³ or more, and still more preferably 0.6 g/cm ³ . Above, more preferably 0.65 g/cm ³ or more, preferably 1.2 g/cm ³ or less, more preferably 1.1 g/cm ³ or less, still more preferably 1.0 g/cm ³ or less, More preferably 0.9 g/cm ³ or less, particularly preferably 0.85 g/cm ³ or less.
The density of the paper base is calculated from the thickness and basis weight of the paper base.

The content of the paper substrate in the base paper for deep drawing processing is preferably 30% by mass or more, more preferably 40% by mass or more, and still more preferably 50% by mass, based on the total mass of the base paper, from the viewpoint of reducing environmental load. % by mass or more, more preferably 52% by mass or more, particularly preferably 55% by mass or more, and the upper limit is not particularly limited, and may be 100% by mass.

[Other layers]
<Pigment coating layer>
The base paper for deep drawing processing of the present embodiment may optionally have a coating layer containing a pigment and an adhesive on at least one surface of the paper base layer. By providing such a coating layer, it is possible to impart good printability to the surface of the base paper for deep drawing processing. Furthermore, any ink such as dye ink or pigment ink may be used and a printing layer may be provided using a commonly used printing machine.
Known pigments such as calcium carbonate, kaolin, clay, talc, titanium oxide and plastic pigments can be arbitrarily used as the pigment used in the pigment coating layer.
Known adhesives such as starch, casein, SBR latex, and polyvinyl alcohol can be arbitrarily used as the adhesive used for the pigment coating layer.
These pigment coating layers can be formed as a single layer or multiple layers. In addition, it is desirable that the total coating amount is about 20 g/m ² or more and 30 g/m ² or less. Further, when such a coating layer is provided, it is more preferable that the layer immediately below the pigment coating layer has a higher degree of beating and a smoother surface. Such a coating layer can be applied by appropriately using various known coating apparatuses. Moreover, it is possible to further provide a printing layer on such a pigment coating layer.

<Water resistant coating layer>
The base paper for deep-drawing molding of the present embodiment can be provided with a water-resistant coating layer on one or both sides thereof, as necessary, in order to prevent permeation and leakage of liquid. This water-resistant coating layer may be provided directly on the paper substrate, or may be provided on the pigment coating layer or the printing layer, and may be provided at any desired location.
As a method for providing the water-resistant coating layer, a water-resistant paint may be applied.

Water-resistant paints that are applied to the surface of paper substrates to impart water resistance include emulsions of waxes such as microcrystalline wax and paraffin wax, latexes such as SBR latex and polyvinylidene chloride latex, acrylic emulsions, and self-adhesives. There are various synthetic resin emulsions such as emulsified polyolefins and polyethylene copolymer resin emulsions.
Equipment for applying these water-resistant paints may be any of commonly used bar coaters, air knife coaters, roll coaters, blade coaters, gate rolls, size presses, etc., and is not particularly limited. In addition, it is preferable that the coating amount of these materials is about 1.0 g/m ² or more and 20.0 g/m ² or less as a whole, and these coating layers can be formed as a single layer or multiple layers.

<Thermoplastic resin layer>
The base paper for deep drawing processing of the present embodiment preferably further has a thermoplastic resin layer on at least one surface of the paper base layer. The thermoplastic resin layer may be provided directly on the paper substrate, or may be provided on the pigment coating layer or printing layer. By providing the thermoplastic resin layer, water resistance and gas barrier properties against nitrogen, oxygen, water vapor, etc. can be imparted to the deep-drawn molded product. Therefore, when the deep drawn product is a food container, the thermoplastic resin layer is preferably provided at least on the food contact surface, and preferably provided as the outermost layer of the food contact surface.
The thermoplastic resin used for the thermoplastic resin layer is not particularly limited, and is not particularly limited as long as it is a thermoplastic resin that can be laminated on the paper base layer, and may be appropriately selected from known thermoplastic resins.
Thermoplastic resins include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid, and polybutylene succinate; polyvinyl chloride, polyvinylidene chloride, polybutene, polybutadiene, ethylene-vinyl acetate copolymer , polyethylene, polypropylene, ethylene-propylene copolymer, polyolefin resins such as polymethylpentene; polycarbonate resins; polyurethane resins; polyamide resins such as nylon; polystyrene resins; polyacrylonitrile resins; Ethylene-vinyl alcohol copolymer and the like are exemplified.
Among these, polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymers; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid, and polybutylene succinate; polyamide resins; ethylene-vinyl alcohol copolymers; coalescence is preferred.
Among the above thermoplastic resins, polyethylene is preferred because of its excellent extrusion lamination properties and water resistance. Polyethylene (PE) is roughly classified into linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE). Among these, low-density polyethylene (LDPE) is preferred because of its excellent extrusion lamination properties.
The thermoplastic resin layer may be provided using a thermoplastic resin laminate film, for example, polyamide resin, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, etc., which have excellent gas barrier properties against oxygen, water vapor, nitrogen, etc. It is also preferred to use a multilayer laminate film having at least one layer of If it has a thermoplastic resin layer with nitrogen gas barrier properties, it can be suitably used as a base paper for deep-drawn moldings filled with inert material. Since the base paper for deep drawing processing of the present embodiment has at least one thermoplastic resin layer formed from a resin having excellent gas barrier properties, a molded product having excellent gas barrier properties can be obtained. The thermoplastic resin layer having excellent gas barrier properties is preferably provided on the food contact surface side. Moreover, it is preferable to have a polyolefin layer such as polypropylene or polyethylene, which is excellent in water resistance and laminating properties.
These resins may be used individually by 1 type, and may use 2 or more types together.
Also, the resin layer may be foamed during or after molding to form a foamed resin layer.

The method for laminating the thermoplastic resin layer may be appropriately selected from commonly used wet lamination, hot melt lamination, extrusion lamination, dry lamination, thermal lamination and the like.

<Characteristics of base paper for deep drawing>
(Young's modulus)
Among the Young's modulus in the vertical direction and the Young's modulus in the horizontal direction of the base paper for deep drawing processing, A is 2,600 N/mm ² or less, where A is the larger Young's modulus and B is the smaller Young's modulus. and the Young's modulus ratio C represented by the following formula (1) is 1.00 or more and 1.80 or less.
C=A/B (1)
Among the Young's modulus in the longitudinal direction and the Young's modulus in the transverse direction, the larger Young's modulus A is 2,600 N/mm ² or less, preferably 2,200 N/mm ² or less, more preferably 2,000 N/mm mm ² or less, more preferably 1,800 N/mm ² or less, still more preferably 1,500 N/mm ² or less. Although the lower limit is not particularly limited, it is preferably 800 N/mm ² or more, more preferably 1,000 N/mm ² or more, and still more preferably 1,200 N/mm ² or more.
In addition, the Young's modulus ratio C (ratio of A to B, C=A/B) represented by the above formula (1) is 1.00 or more and 1.80 or less, preferably 1 0.50 or less, more preferably 1.40 or less, even more preferably 1.30 or less, and even more preferably 1.25 or less.
When the Young's modulus A is within the above range, the base paper for deep drawing processing tends to stretch during deep drawing processing, so cracking is suppressed. Further, when the Young's modulus ratio C is within the above range, the difference in Young's modulus between the longitudinal direction and the lateral direction is small, and the moldability is good because it is easily elongated both longitudinally and laterally. In addition, it is preferable because the shape reproducibility is excellent and the strength as a molded product is increased.

(breaking elongation)
From the viewpoint of suppressing the occurrence of cracks during deep drawing, the elongation at break of the base paper for deep drawing processing is 3.0% or more in the longitudinal direction and in the transverse direction, and The geometric mean of the breaking elongation in the transverse direction is 4.0% or more.
The longitudinal direction means the papermaking direction, and the lateral direction means the direction perpendicular to the papermaking direction.
Each of the breaking elongation in the machine direction and the transverse direction is preferably 3.4% or more, more preferably 5.0% or more, still more preferably 7.0% or more, still more preferably 8.0% or more, and particularly preferably is 9.0% or more, and the upper limit is not particularly limited, but from the viewpoint of manufacturability, it is preferably 20% or less, more preferably 15% or less, and still more preferably 12% or less.
The geometric mean of the breaking elongation in the machine direction and the transverse direction is preferably 4.5% or more, more preferably 5.0% or more, still more preferably 7.0% or more, and even more preferably 10.0% or more. Although the upper limit is not particularly limited, it is preferably 20% or less, more preferably 16% or less, and still more preferably 12% or less from the viewpoint of manufacturability.
The elongation at break of the base paper for deep drawing processing is measured in accordance with JIS P 8113:2006, and the base paper is left at rest in an environment of 23±5° C. and 50±10% RH for one day or more, and the temperature and humidity are controlled. is measured for Details are as described in Examples.

(paper thickness)
The paper thickness of the base paper for deep drawing processing (thickness of base paper) is preferably 0.10 mm or more, more preferably 0.20 mm or more, from the viewpoint of strength as a molded product and suppression of breakage during deep drawing processing. , more preferably 0.30 mm or more, still more preferably 0.35 mm or more, and preferably 0.90 mm or less, more preferably 0.70 mm or less, even more preferably 0.60 mm or less, still more preferably 0 .50 mm or less.
The thickness of the base paper for deep drawing processing is measured according to JIS P 8118:2014.

(basis weight)
The basis weight of the base paper for deep drawing processing is preferably 100 g/m ² or more, more preferably 150 g/m ² or more, and still more preferably from the viewpoint of strength as a molded article and suppression of breakage during deep drawing processing. is 200 g/m ² or more, more preferably 225 g/m ² or more, and is preferably 500 g/m ² or less, more preferably 450 g/m ² or less, still more preferably 400 g/m ² or less, and even more preferably is 385 g/m ² or less.
The basis weight of the base paper for deep drawing processing is measured according to JIS P 8124:2011.

(density)
The density of the base paper for deep drawing processing is preferably 0.60 g/cm ³ or more, more preferably 0.65 g/cm ³ or more, from the viewpoint of strength as a molded article and suppression of breakage during deep drawing processing. and is preferably 1.2 g/cm ³ or less, more preferably 1.1 g/cm ³ or less, and even more preferably 1.0 g/cm ³ or less.
The density of base paper is calculated from the paper thickness and basis weight.

[Deep drawing]
The deep-drawn product of the present embodiment is formed using the base paper for deep-drawing processing described above. That is, the deep drawn product of the present embodiment is obtained by, for example, pressing, vacuum forming, or pressure forming the base paper described above.
<Manufacturing method of deep drawn product>
(1) Adjusting the Moisture Content of Base Paper As a method for producing a deep-drawn product according to the present embodiment, a container blank sheet is punched out from a base paper for deep-drawing processing, and the blank sheet is sandwiched between a press mold consisting of a male mold and a female mold, and heated. , press molding, which is a manufacturing method called press molding. Also, under heating, only the male or female mold is used, and a vacuum is created between the mold and the blank sheet to form the sheet in close contact with the mold. Pneumatic molding is exemplified in which a sheet is sandwiched between one mold and the other air pressure device using molds, and the sheet is formed in close contact with the mold by pressure from the pressure device.
At this time, it is preferable that the base paper for deep drawing processing is pre-humidified to adjust the water content of the base paper. The moisture content of the base paper is preferably 10% to 20%, more preferably 11% to 17%, still more preferably 12% to 15%, and most preferably 12.5% to 14.5%. Note that the water content of the base paper as used herein refers to the percentage of water by mass with respect to the absolute dry weight of the entire base paper for deep drawing processing including the thermoplastic resin layer. When the moisture content of the base paper is within this preferred range, plasticization of the base paper for forming and processing occurs, improving formability, and breaking of the paper layer during forming can be reduced. As a result, it is possible to obtain a draw-formed product that has a greater depth, a smooth and beautiful appearance, and high rigidity.
As a method for adjusting the moisture content of the base paper, there is a method of supplying moisture to the base paper immediately before press molding, and a method of humidifying after exiting the dryer during papermaking of the paper base material, and transporting and storing in a state where the moisture is maintained. etc.

(2) Molding method Next, a process for manufacturing a molded article from a blank sheet will be described.
When deep drawing is performed by press working in this embodiment, it is performed using a pair of press dies. The pair of hot press dies are a convex mold having a shape corresponding to the internal volume of the molded product and a concave mold having a shape corresponding to the outer shape of the molded product. At least one of the pair of press dies moves back and forth or up and down to press the molded product. For convenience of explanation, the convex mold is used as the upper mold, the concave mold is used as the lower mold, and the pressing method (FIG. 1) is explained by moving the upper mold downward.
In FIG. 1(A), a convex mold (male mold) 1 is used as an upper mold, a concave mold (female mold) 2 is used as a lower mold, and deep drawing is performed between the convex mold 1 and the concave mold 2. A blank sheet 3 obtained by punching a base paper for molding into a desired shape in advance is sandwiched between them, and a convex mold (male mold) 1 is moved from above to below to perform pressure molding (press molding) on the blank sheet. Mold into the desired shape. At this time, as described above, it is preferable to perform pressure molding under heating. As shown in (B), a molded product is obtained by moving a convex mold (male mold) 1 upward.
When deep drawing is performed by vacuum forming, only one of the female and male molds is used to form the sheet into a shape that fits the mold. Preferably, the gap between the blank sheet and the mold is decompressed under heating, the blank sheet is brought into close contact with the mold and molded, and if necessary, after cooling, air is blown in to take out the molded product.
When deep drawing is performed by air pressure molding, either a male or female mold and an air pressure device (also called a pressure box) are used to form a shape that matches the mold. A blank sheet is sandwiched between a mold and an air pressure device, and the sheet is preferably pressed against the mold under heating by pressure from the pressure device.

As a method for heating the blank sheet, a method such as high-frequency heating, hot air heating, or infrared heating may be used. Alternatively, the entire mold may be heated. In this case, means for heating the mold are required. As a means for heating the mold, heating is generally performed by providing an electric heating device to the mold, but there is also means for drying by connecting a high-frequency oscillator to the mold and applying high-frequency waves. Electric heating and high-frequency heating can also be used together.

The heating temperature during molding is preferably in the range of 100° C. or higher and 150° C. or lower, more preferably 110° C. or higher and 140° C. or lower. When the heating temperature is 100° C. or higher, molding is performed in a short period of time, thereby improving productivity. In addition, when the temperature is 150° C. or less, the formation of blisters is suppressed even when the moisture content of the base paper is particularly high, which is preferable. The base paper for deep drawing processing can be brought to the predetermined temperature when set in the above-described heated press machine, vacuum machine, or pneumatic machine. As another means, it is also possible to apply electromagnetic waves such as microwaves to the base paper for deep drawing processing containing moisture to raise the temperature, and then introduce it into a press machine, a vacuum machine, or a pneumatic machine.

A molded product that has completed deep drawing may be removed from the mold and air-cooled, but in order to improve dimensional stability, it is also possible to fix and cool the hot molded product in a cooling mold for a certain period of time. preferable.

Known materials such as aluminum, aluminum-based alloys, brass, iron, stainless steel, and ceramics can be used as materials for the mold.

Any method of hydraulic press, air cylinder, or cam mechanism can be used to operate the mold. As a specific method for controlling the clearance between the upper mold and the lower mold in this embodiment, in the case of using hydraulic pressure or air pressure, the pressure may be controlled by computer control according to the thickness of the molded product. position may be controlled. In the case of using a cam mechanism, it is possible to control by the previously designed cam shape and the lowering speed of the mold.
The press time during press molding is preferably 2 seconds or more and 30 seconds or less from the viewpoint of moldability and workability.

<Shape of molded product>
The deep drawn product of the present embodiment is a molded product obtained by molding a sheet of base paper for deep drawing processing. The molded product is preferably obtained by drawing with a pair of convex (male) and concave (female) press dies.
The molded product is preferably a container, typically having an open top and a flange at the top edge. Also, the flange may be formed by curling.

The outer shape of the container in plan view may be square, rectangular, circular, elliptical, or the like. For each shape, the corners are usually rounded. An example of the deep-drawn container of this embodiment is shown in FIG. 2 as a plan view (A) and a front view (B).

The characteristics of the present invention will be described more specifically below with reference to examples and comparative examples. Materials, usage amounts, proportions, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.

[Evaluation and analysis]
The following evaluations and analyzes were carried out on raw material pulps and deep-drawing base papers of Examples and Comparative Examples.

[Raw material pulp]
<Measurement of Canadian Standard Freeness (CSF)>
The Canadian Standard Freeness (CSF) of raw material pulp was measured according to JIS P 8121-2:2012.

[Base paper for deep drawing]
<Thickness (paper thickness)>
The thickness of the base paper for deep drawing processing was measured according to JIS P 8118:2014.
In the case of having a resin layer, the thickness of each of the paper base layer and the thermoplastic resin layer was measured from an electron microscope (SEM) observation image of the cross section of the base paper for deep drawing processing.

<Basis weight>
The basis weight of the base paper for deep drawing processing was measured according to JIS P 8124:2011.

<Density>
The density of the base paper for deep drawing processing was calculated from the thickness and basis weight obtained by the measurement method described above.

<Measurement of length-weighted average fiber length, number ratio of fine fibers, and curl value>
The base papers for deep drawing processing of Examples and Comparative Examples were cut into 40 cm squares, soaked in deionized water to adjust the concentration to 2%, and soaked for 24 hours.
After soaking for 24 hours, the pulp was defiberized by using a standard defiberizer (manufactured by Kumagai Riki Kogyo Co., Ltd.) until there were no undisintegrated fibers. In the case of having a resin layer, the slurry (dispersion of pulp fibers) after defibering excluding the resin layer is separated, and a fiber length measuring machine (model FS-5 with UHD base unit, manufactured by Valmet) is used. "Length-loaded average fiber length (ISO)", "fine fiber amount (FinesA)", and "curl value" were measured.
The "length-weighted average fiber length (ISO)" is the length-weighted average fiber length calculated by selecting fibers of 0.2 mm or more and 7.6 mm or less.
The "fine fiber amount (FineA)" is the ratio of the number of fine fibers having a fiber width of 75 µm or less and a length of 0.2 mm or less in the disaggregated pulp fibers.

<Breaking elongation>
In accordance with JIS P 8113:2006 (testing method for tensile properties of paper and paperboard), the base paper was left to stand in an environment of 23 ± 5 ° C and 50 ± 10% for 1 day or more, and the temperature and humidity were adjusted to a width of 15 mm. , a sample cut to a length of 150 mm was prepared.
Using a tensile tester (model RTC-1210A, manufactured by A&D Co., Ltd.), the sample was mounted so that the distance between chucks was 100 mm, and a tensile test was performed at a speed of 20 mm / min. (Transverse direction) The breaking elongation of each was measured.

<Young's modulus>
T (longitudinal direction) and Y (transverse direction) tensile tests were performed in the same manner as for the elongation at break, except that the speed was changed to 240 mm/min.
The Young's modulus was obtained by calculating the slope of the obtained chart at an elongation of 0 to 1%.

<Formability: Suppression of crack generation>
Blank sheets were obtained by cutting out the base papers for deep drawing processing of Examples and Comparative Examples. A blank sheet is molded using a molding die and a press molding machine (FVT400, manufactured by Wakisaka Engineering Co., Ltd.) under the conditions of a press pressure of 35 kgf/cm ² , a press temperature of 150° C., and a press time of 5 seconds, as shown in FIG. Molded into a tray shape. 200 molded articles were produced and the following evaluations were performed.
Evaluation criteria are as follows.
(Evaluation criteria)
A: Among the molded paper trays, the ratio of paper trays without cracks is 98% or more B: Among the molded paper trays, the ratio of paper trays without cracks is 95% or more and less than 98% C: Molding Among the molded paper trays, the ratio of paper trays without cracks is 90% or more and less than 95% D: Among the molded paper trays, the ratio of paper trays without cracks is less than 90%

<Formability: shape reproducibility>
The molded paper tray was placed on a desk, and the center of the long side of the four sides was pressed with a finger until it touched the desk, and the following evaluations were made.
Evaluation criteria are as follows.
A: Press to the ground with your finger and stop after shaking within 2 times.
B: Press to the ground with your finger and stop after shaking 3 times or more and 5 times or less.
C: Push it to the ground with your finger, shake it 6 times or more, and then stop.
When the shape reproducibility with respect to the molding die is high, a flat bottom surface is formed. As a result, when the shape reproducibility is excellent, it stops with a small amount of shaking, but when the shape reproducibility is poor, the number of times it shakes until it stops increases.

[Preparation of pulp]
<Preparation of Pulp 1>
Using NUKP (unbleached softwood kraft pulp) obtained by pulping (cooking) wood, beaten until CSF (Canadian Standard Freeness) reaches 650 mL at low concentration (2 mass% slurry concentration at beating). Then, Pulp 1 was prepared.

<Preparation of pulp 2>
NBKP (softwood bleached kraft pulp) obtained by pulping (cooking) and bleaching wood is used. concentration of 2% by mass), and beaten to a CSF (Canadian Standard Freeness) of 600 mL to prepare pulp 2.
Bleached kraft pulp tends to have a reduced number ratio of fine fibers due to repeated dehydration treatment in bleaching treatment.
Further, high-concentration beating tends to increase the curl value.

<Preparation of Pulp 3>
In the preparation of pulp 1, pulp was prepared in the same manner as pulp 1, except that the first stage beating was changed to high-concentration beating (pulp concentration at beating 30% by mass) and the second-stage beating was low-concentration beating. 3 (650 mL CSF) was prepared.

<Preparation of Pulp 4>
Pulp 4 (CSF 550 mL) was prepared in the same manner as Pulp 1, except that 30 parts by mass of NBKP (softwood bleached kraft pulp) and 70 parts by mass of LBKP (broadleaf bleached kraft pulp) were used as the raw material pulp in the preparation of pulp 1. did.
Softwood pulp tends to have a longer fiber length than hardwood pulp.

[Examples and Comparative Examples]
<Production of paper substrate (Examples 1 to 5)>
Using the pulp shown in Table 1, 0.2 parts by mass of synthetic sizing agent (SPS400, manufactured by Arakawa Chemical Industries, Ltd.), 1.0 part by mass of aluminum sulfate, and 1.0 parts by mass of aluminum sulfate, as a retention agent, per 100 parts by mass of pulp in terms of solid content 0.5 parts by mass of polyacrylamide resin (manufactured by Seiko PMC Co., Ltd., DS4433) and 0.025 parts by mass of nonionic polyacrylamide (manufactured by Allied Colloid, Percol 47) as a polymer flocculant (retention agent) are added, Stock was prepared. Using the above stock, a wet paper machine (Bellform III, manufactured by Mitsubishi Heavy Industries, Ltd.) equipped with a stretching device (manufactured by Clupak) is used to make paper at a papermaking speed of 600 m/min, and crepe is applied to the surface of the paper. A paper substrate was obtained.
The basis weight of the single paper of the paper substrate used in each example was 68 g/m 2 for Example 1, 69 g/m ² for Example 2, 67 g/m ² for Example 3, and 67 g/m ² for Example 4. 63 g/m ² and Example 5 was 73 g/m ² .

<Production of polysand paper (Examples 1 to 5)>
One side of the paper base material (single paper) obtained as described above is melt-extrusion coated with LDPE (LC-522, manufactured by Japan Polyethylene Co., Ltd.) to a thickness of 20 μm, and the same paper base material (single paper) is coated on the coated surface. ) is laminated, and one side of the paper base material is similarly melt-extruded coated with LDPE to a thickness of 20 μm, and the same paper base material (single paper) is laminated to the coated surface to form a three-layer paper base layer. A polysand paper (paper base/LDPE/paper base/LDPE/paper base) was obtained.

<Production of paper substrate (Example 6, Comparative Examples 1 to 3)>
Using the pulp shown in Table 1, 0.2 parts by mass of synthetic sizing agent (SPS400, manufactured by Arakawa Chemical Industries, Ltd.), 1.0 part by mass of aluminum sulfate, and 1.0 parts by mass of aluminum sulfate, as a retention agent, per 100 parts by mass of pulp in terms of solid content 0.02 parts by weight of a cationic retention agent (ND-300, manufactured by Hymo Co., Ltd.) and 0.025 parts by weight of nonionic polyacrylamide (Percol 47 manufactured by Allied Colloid) as a polymer flocculant are added to prepare paper. prepared. Using the above stock, paper was made at a papermaking speed of 600 m/min with a wet paper machine (Bellform III, manufactured by Mitsubishi Heavy Industries, Ltd.) to obtain a paper base material. In addition, Example 6 was made at a J/W ratio of 1, and Comparative Examples 1 to 3 were made at a J/W ratio of 1.1.
The basis weight of the single paper was 278 g/m 2 in Example 6, 338 g/m ² in Comparative Example 1, 303 g/m ² in Comparative Example ^{2, and 297 g/m 2 in} Comparative Example 3.

[Examples 1, 2, 4, 5, 6, Comparative Examples 2, 3]
A curing agent (CAT- ^EP8 , Toyo-Morton Co., Ltd.) was mixed with a coating liquid of 3 parts by mass and coated using a reverse roll coater. Next, a thermoplastic resin film was wet-laminated on the surface coated with the adhesive.
The thermoplastic resin films L1 and L2 are as follows. In L1 and L2, the layers were laminated so that the PA was on the paper substrate side.
・ L1: CEL-4264D (manufactured by Sumitomo Bakelite Co., Ltd., PE (polyethylene) / PA (polyamide) / EVOH (ethylene-vinyl alcohol copolymer) / PA (polyamide) laminated film), thickness = 60 μm
・ L2: Diamyron MFC673 (manufactured by Mitsubishi Chemical Corporation, PP (polypropylene) / EVOH (ethylene-vinyl alcohol copolymer) / PA (polyamide) laminated film), thickness = 60 μm
Further, in Examples 1, 2, 5, 6 and Comparative Examples 2 and 3, a thermoplastic resin layer was provided on the opposite side to the side on which L1 or L2 was provided. Specifically, a water-based acrylic adhesive (EA-G34, manufactured by Toyo-Morton Co., Ltd.) 100 was applied to the surface opposite to the surface on which L1 or L2 was provided so that the coating amount after heat drying was 10 g/m ² . A coating solution in which 3 parts by mass of a curing agent (CAT-EP8, manufactured by Toyo-Morton Co., Ltd.) was mixed with the parts by mass was coated using a reverse roll coater. Next, a thermoplastic resin film was wet-laminated on the surface coated with the adhesive.

[Example 3, Comparative Example 1]
In Example 3, the obtained polysand paper was used as it was as a base paper for deep drawing.
In Comparative Example 1, the obtained paper substrate was used as it was as a base paper for deep drawing processing.

The obtained base paper for deep drawing processing was evaluated as described above.
Results are shown in the table below.

From the results of Examples and Comparative Examples, it was found that the base paper for deep drawing of the present invention suppresses the occurrence of cracks during deep drawing, has excellent shape reproducibility, and has excellent deep drawability. Recognize.

INDUSTRIAL APPLICABILITY The base paper for deep drawing of the present invention suppresses the occurrence of cracks during deep drawing and has excellent shape reproducibility.

Claims (6)

It is a base paper for deep drawing processing,
The base paper comprises a paper substrate layer made of a paper substrate,
The length-weighted average fiber length of the pulp constituting the paper substrate is 0.60 mm or more and 2.40 mm or less,
Where A is the larger Young's modulus of the longitudinal Young's modulus and the transverse Young's modulus of the base paper, and B is the smaller Young's modulus, A is 2,600 N/mm ² or less, and ,
Young's modulus ratio C represented by the following formula (1) is 1.00 or more and 1.80 or less,
C=A/B (1)
The base paper has an elongation at break in the machine direction and the transverse direction of 3.0% or more, respectively, and a geometric mean of the elongation at break in the machine direction and the transverse direction of 4.0% or more.
Base paper for deep drawing processing. 2. The base paper for deep drawing according to claim 1, wherein the Young's modulus ratio C is 1.00 or more and 1.50 or less. 3. The base paper for deep drawing processing according to claim 1 or 2, wherein the curl value of the pulp constituting the paper base material is 5% or more and 12% or less. The base paper has a basis weight of 100 g/m ² or more and 500 g/m ² or less, a paper thickness of 0.10 mm or more and 0.90 mm or less, and a density of 0.60 g/cm ³ or more and 1.2 g/cm ³ . The base paper for deep drawing processing according to any one of claims 1 to 3, wherein: The base paper for deep drawing processing according to any one of claims 1 to 4, further comprising a thermoplastic resin layer on at least one surface of said paper base layer. A deep-drawn product using the base paper for deep-drawing processing according to any one of claims 1 to 5.

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