JP7412115B2 - Base paper for paper cups - Google Patents

Description

The present invention relates to base paper for paper cups that uses less plastic. The present invention also relates to base paper for paper cups that has excellent processability. In particular, it relates to base paper for paper cups that has excellent heat-sealability and top curl processing suitability.

In recent years, the plastic waste problem has become more serious. The world's plastic production is said to exceed 400 million tons per year, and the packaging and containers sector produces a large amount of plastic, contributing to plastic waste. Plastic does not decompose semi-permanently, and its garbage turns into microplastics in the natural environment, which has a serious negative impact on the ecosystem. The most common plastics used in packaging containers are polyethylene terephthalate (PET), which is used in beverage cups and bottles, and polyethylene (PE) and polypropylene (PP), which are used in plastic bags and container laminates. Used a lot. The oceans are particularly polluted, and the plastic waste is said to be impossible to collect. In the future, it is necessary for the global environment to reduce the use of plastic.

On the other hand, applications of biodegradable plastics that can be completely decomposed by microorganisms are being proposed around the world as a countermeasure against plastic waste. Biodegradable plastics decompose within a certain period of time in the natural world, but until they are decomposed they are still garbage, and unless the amount of their use and disposal is reduced, this cannot be said to be an immediate measure. (See Patent Documents 1 and 2).

As an immediate countermeasure, it has been proposed, for example, to replace plastic with paper, and this is widely used in paper cups. However, when processing paper into paper cups, a large amount of polyethylene or polypropylene is laminated and used as a heat sealing agent. The amount of these plastics laminated varies depending on the product concept, but is generally 20 to 50 g/m ² , and can be as large as 300 g/m ² . Therefore, even in paper cups in which plastic is replaced with paper, there is still a problem that the amount of plastic used is not sufficiently reduced, and there is an urgent need for a means to directly reduce the use of plastic.

Japanese Patent Application Publication No. 2012-148444 Japanese Patent Application Publication No. 2013-141763

An object of the present invention is to provide a base paper for paper cups that can reduce the amount of plastic used and, in particular, has heat sealability and top curl processing suitability.

In the present invention, an ionomer is used in order to reduce the amount of polyethylene or polypropylene used in conventional plastic laminated paper (hereinafter sometimes abbreviated as polylaminated paper). That is, the paper cup base paper according to the present invention is a paper cup base paper having at least one heat seal layer on at least one surface of a paper base material, the heat seal layer containing an ionomer, and the heat seal layer containing an ionomer. The coating amount is 2 to 10 g/m ² . Compared to the amount of polyethylene or polypropylene used in the heat-sealing layer of conventional polylaminated paper, which exceeds 20g/ ^m2 , the amount of plastic used for the heat-sealing layer has been reduced to approximately 10-50% of the conventional amount. can be reduced. Here, the ionomer is a synthetic resin in which polymers are aggregated using the cohesive force of metal ions, and is a synthetic resin in which acrylic acid or methacrylic acid is combined with ethylene or the like. For example, it is produced by adding metal cations such as sodium or zinc to an acrylic polymer and ethylene to cause intermolecular bonding.

Further, in the present invention, the lateral Taber bending resistance (JIS P-8125-2) of the paper cup base paper is 1 mN·m to 10 mN·m. Since the hot tack of the ionomer is lower than that of polyethylene, if the Taber bending resistance exceeds 10 mN·m, poor adhesion will occur during heat sealing (even if once bonded, the bonded portion will peel off due to the rigidity of the paper). Moreover, if it is less than 1 mN·m, it is too soft as a paper cup.

Further, the basis weight is preferably 80 g/m ² to 400 g/m ² . This makes it difficult for top curl cracks to occur particularly when processing paper cups (including paper cups for ice cream).

It is preferable that the paper cup base paper has a specific volume of 0.8 to 1.8 cm ³ /g. Within this range, it is possible to obtain a paper with suitable bending resistance for use as a paper cup, which makes it difficult for top curl cracks to occur particularly during processing of paper cups (including paper cups for ice cream).

It is preferable that the longitudinal tensile elongation at break (JIS P-8113) of the paper cup base paper is 1% or more. Top curl cracking is likely to occur. This makes it difficult for top curl cracks to occur particularly when processing paper cups (including paper cups for ice cream).

In the paper cup base paper of the present invention, the paper base material contains pulp as a main component, and the freeness of the pulp meets the Canadian Standard Freeness (JIS P 8121:1995 "Pulp Freeness Testing Method"). ), preferably 350 to 420 ml CSF. Within this range, it is possible to obtain a paper with suitable bending resistance for use as a paper cup, which makes it difficult for top curl cracks to occur particularly during processing of paper cups (including paper cups for ice cream).

According to the present invention, it is possible to produce base paper for paper cups in which the amount of plastic used is reduced. The base paper for paper cups of the present invention can reduce the negative impact of plastic waste on the natural environment even if it is inappropriately released as garbage into the natural world, and can help solve the plastic waste problem. This will help solve the problem. The base paper for paper cups of the present invention is excellent as, for example, paper cups for hot and iced drinks, cups for food such as ice cream, and cups for food such as hot snacks.

Next, the present invention will be described in detail by showing embodiments, but the present invention should not be interpreted as being limited to these descriptions. The embodiments may be modified in various ways as long as the effects of the present invention are achieved.

In this embodiment, the ionomer is a general term for synthetic resins in which polymers are aggregated using the cohesive force of metal ions, and is a resin in which acrylic acid or methacrylic acid is combined with ethylene or the like. In other words, metal salts of ethylene/methacrylic acid copolymers, metal salts of ethylene/acrylic copolymers, metal salts of ethylene/urethane copolymers, metal salts of ethylene/fluoropolymer copolymers, etc. All are called ionomers. Examples of metals that form salts include alkali metal ions and alkaline earth metal ions, specifically sodium, potassium, calcium, magnesium, and zinc ions. In the present invention, it is preferable that the ionomer is a self-emulsifying emulsion in which the ionomer is a metal salt of an ethylene/methacrylic acid copolymer. A heat-sealing layer having sufficient heat-sealing strength can be provided even if the coating amount of the heat-sealing layer is relatively small.

In this embodiment, a heat seal layer can be provided by applying a heat seal layer coating liquid containing an ionomer emulsion to at least one surface of a paper base material and drying the coating liquid. By using an ionomer emulsion, it is possible to control the amount of coating to be relatively low, and furthermore, by using an aqueous ionomer emulsion, VOC emissions are eliminated and the load on the natural environment can be reduced. The coating amount of the heat-sealing layer is 2 to 10 g/m ² , preferably 3 to 8 g/m ² in terms of solid content, per one side of the paper base material. If it is less than 2 g/m ² , sufficient heat sealing strength cannot be achieved. Specifically, the heat seal strength becomes less than 145 (gf/4 mm). On the other hand, if it exceeds 10 g/m ² , the quality is excessive in terms of heat sealing strength and the plastic reduction effect is poor. In addition, in the base paper for paper cups of the present invention, the heat seal layer is usually provided not only on a part of the surface of the paper base material but on the entire surface. In other words, the heat-sealing layer is not provided only in areas necessary for heat-sealing, such as in the form of a net, island, or line, but is provided so as to cover the entire surface of the paper base material. Good.

In addition to the ionomer emulsion, various auxiliary agents may be added to the coating liquid for the heat seal layer. Examples include viscosity modifiers, antifoaming agents, leveling agents such as surfactants and alcohols, colored pigments, and colored dyes. However, since the addition of these auxiliary agents tends to cause a decrease in heat sealing strength, it is preferable that they be added in small amounts. In this embodiment, it is preferable that the coating liquid for the heat seal layer consists of only an ionomer emulsion.

The method of applying the heat seal layer coating liquid is not particularly limited, and commonly used coating equipment can be used. For example, air knife coater, blade coater, gravure coater, rod blade coater, roll coater, reverse roll coater, bar coater, curtain coater, die slot coater, champlex coater, metering blade type size press coater, short dwell coater, spray Various known coating devices such as a coater, gate roll coater, lip coater, etc. can be used.

In this embodiment, it is preferable that the heat seal layer is formed of two or more layers. By having two or more layers, the air permeability of the base paper for paper cups can be increased, and water repellency and oil repellency can also be imparted, and properties similar to or similar to those of plastic film laminated paper can be obtained. This is because it can be done. When there are two or more heat-sealing layers, it is preferable that the coating amount of the lowest heat-sealing layer closest to the paper base material is larger than the total coating amount of the other heat-sealing layers. This is because the air permeability of the paper cup base paper can be further improved, and the water repellency and oil repellency are further improved.

The water content of the paper cup base paper is preferably 3% to 10%. If it is less than 3%, top curl cracking is likely to occur. If it exceeds 10%, it will be too soft as a paper cup. Preferably it is 4% to 9%. Moisture can be adjusted by drying the base paper for paper cups.

The paper cup base paper has a specific volume of 0.8 to 1.8 cm ³ /g. If it is less than 0.8, the top curl is likely to break. If it is less than 0.8, the top curl will be easily broken, and if it exceeds 1.8 cm ³ /g, it will be too soft as a paper cup. Preferably, the paper cup base paper has a specific volume of 0.9 to 1.7 cm ³ /g.

Further, the paper cup base paper of the present invention has a basis weight of 80 g/m ² to 400 g/m ² . Preferably, the paper cup base paper has a basis weight of 180 g/m ² to 300 g/m ² . If the basis weight is within this range, top curl cracking will be eliminated, especially when processing paper cups (including paper cups for ice cream). If the basis weight exceeds 400 g/m ² , the adhesive becomes rigid and bending resistance increases too much, making it impossible to obtain sufficient adhesive strength during adhesive processing. Moreover, if the basis weight is less than 80 g/m ² , the bending resistance and strength necessary for the paper cup cannot be obtained.

The longitudinal tensile elongation at break (JIS P-8113) of the paper cup base paper is 1% or more. If it is less than 1%, top curl cracking tends to occur. Preferably it is 1.2% or more. Note that the vertical direction in the present invention refers to the longitudinal direction (MD), and the horizontal direction refers to the cross-grain direction (CD).

In this embodiment, it is preferable that the air permeability of the paper cup base paper exceeds 10,000 seconds. More preferably, it is 12,000 seconds or more, and still more preferably 15,000 seconds or more. By setting the air permeability of the base paper for paper cups to 10,000 seconds or more, the barrier property in the sense of blocking air becomes even higher, and the water repellency and oil repellency are further improved. The method of increasing the air permeability of the paper cup base paper to 10,000 seconds or more is not particularly limited, but it can be achieved, for example, by using a paper base material with high air permeability. Furthermore, the air permeability of the base paper for paper cups can also be increased by increasing the smoothness of the surface to which the heat seal coating liquid is applied. This is because pinholes, cracks, etc. can be further reduced in the heat-sealing layer formed thereafter. For example, by providing a pigment coating layer and then performing a calender treatment or the like, it is possible to increase the smoothness of the surface to which the heat seal coating liquid is applied. In addition, applying two or more heat-sealing layers has the effect of increasing air permeability. Two-layer coating of the heat-sealing layer removes minute pinholes and cracks that exist in the first coating layer (lower layer) and removes minute pinholes and cracks that exist in the first coating layer (lower layer). It is thought that air permeability will increase by covering it. Furthermore, increasing the coating amount of the heat seal layer is also effective in improving air permeability. In terms of film formation of the heat-seal layer, the air permeability can be easily improved by setting the drying temperature of the heat-seal layer coating solution after application to a temperature equal to or higher than the melting point of the ionomer.

In this embodiment, it is preferable that the surface of the paper base material to which the heat seal coating liquid is applied has a smoothness of 10 seconds or more. More preferably, it is 20 seconds or more. The higher the smoothness of the paper base material, the more uniform the thickness of the coated heat-sealing layer will be (less likely to produce minute irregularities), and as a result, variations in heat-sealing strength will be less likely to occur. Uniform heat seal strength can be imparted on a flat surface. The method of increasing the smoothness of the paper base material is not particularly limited, and examples thereof include calendering using a known calendering device such as a super calender, a gloss calender, a shoenip calender, and a soft calender. . Further, paper with a Yankee dryer mirror surface transferred thereto, such as single gloss kraft paper, is also suitable as a highly smooth paper base material. Note that the heat-sealing layer may have pinholes or cracks that are invisible to the naked eye, but as long as they are to that extent, they do not adversely affect the heat-sealability. Furthermore, a leveling agent for the purpose of preventing pinholes may be added to the heat seal layer coating solution as long as the effects of the present invention are not impaired.

The paper base material used in this embodiment is not particularly limited, and any known paper base material containing pulp as a main component can be used. Pulps that are the main component of paper base materials include chemical pulps such as LBKP (hardwood bleached kraft pulp) and NBKP (softwood bleached kraft pulp), GP (groundwood pulp), PGW (pressurized groundwood pulp), and RMP (refiner mechanical pulp). pulp), mechanical pulps such as TMP (thermomechanical pulp), CTMP (chemothermomechanical pulp), CMP (chemimechanical pulp), and CGP (chemiground pulp), wood pulps such as DIP (deinked pulp), kenaf, and bagasse. Non-wood pulps such as , bamboo, cotton, etc. can be used. These can be used alone or mixed in any proportion. For example, 90 to 100 parts by mass of LBKP (broad-leaved bleached kraft pulp) can be used as the pulp. On the other hand, in order to minimize top curl cracking and increase strength and bending resistance, it is preferable to blend softwood pulp. For example, it is preferable to use 50 to 95 parts by mass of softwood pulp and 5 to 50 parts by mass of hardwood pulp in the total pulp. Alternatively, only softwood pulp may be used. Furthermore, synthetic fibers may be further blended within a range that does not impair the intended effects of the present invention. From the viewpoint of environmental conservation, ECF (Elemental Chlorine Free) pulp, TCF (Total Chlorine Free) pulp, waste paper pulp, and pulp obtained from planted trees are preferred. For example, suitable pulp freeness is 200 to 700 ml CSF, for example, 250 to 520 ml CSF, and is 350-420 ml CSF. If the freeness is in this range, it is possible to obtain a paper with suitable bending resistance for paper cups, which makes it difficult for top curl cracks to occur especially when processing paper cups (including paper cups for ice cream). Furthermore, if the freeness exceeds 700 ml CSF, the resulting paper may lack bending resistance and may be too soft as a paper cup.

Paper base materials containing fillers can also be used. Examples of the filler include light calcium carbonate, heavy calcium carbonate, talc, clay, kaolin, calcined clay, titanium dioxide, and aluminum hydroxide. The filler content in the paper base is, for example, 1 to 30 parts by weight based on 100 parts by weight of the dry pulp. For example, it is preferable to include 1 to 10 parts by mass of light calcium carbonate per 100 parts by mass of dry pulp.

In addition to the pulp and filler, the paper base material may also contain various known papermaking additives. Examples of papermaking additives include water-soluble polymers such as starch, sizing agents, internal paper strength enhancers such as wet paper strength enhancers, bulking agents, retention improvers, drainage improvers, colored dyes, and colorants. These include pigments, optical brighteners, optical decolorizers, and pitch control agents. For example, 0.1 to 1.0 parts by weight of a sizing agent, especially a rosin sizing agent, per 100 parts by weight of pulp, and 0.1 to 1.0 parts by weight of starch, especially a cationic sizing agent, per 100 parts by weight of pulp. It is preferable to contain converted starch. Furthermore, water-soluble polymers such as starch, polyvinyl alcohol, and polyacrylamide may be coated.

The paper making method for the paper base material is not particularly limited, and includes a Fourdrinier paper machine, a Fourdrinier multilayer paper machine, a cylinder paper machine, a cylinder multilayer paper machine, a Fourdrinier cylinder combination multilayer paper machine, and a twin wire paper machine. It can be manufactured using various paper machines such as paper machines. Further, in the present invention, the paper base material may be a single-layer paper, a multi-layer paper, or a laminated product of multiple layers.

The paper base material may be provided with one or more coating layers other than the heat seal layer, for example, a pigment coating layer containing a pigment and an adhesive may be provided. As the pigment in the pigment coating layer, known pigments used in the coating layer of general coated printing paper can be used, such as calcium carbonate (heavy calcium carbonate, light calcium carbonate, etc.), Kaolin (including clay), calcined clay, talc, magnesium carbonate, barium sulfate, calcium sulfate, titanium dioxide, zinc oxide, zinc sulfate, zinc carbonate, calcium silicate, aluminum silicate, magnesium silicate, diatomaceous earth, aluminum hydroxide, hydroxide Examples include inorganic pigments such as magnesium, acrylic, styrene, vinyl chloride, nylon themselves, and organic pigments obtained by copolymerizing these (so-called plastic pigments). For example, a combination of 20 to 40 parts by weight of kaolin and 60 to 80 parts by weight of ground calcium carbonate can be used as the pigment. In addition, the adhesive can be a known adhesive used in the coating layer of general coated printing paper, such as butadiene-based copolymer latex, crosslinking agent-modified starch, oxidized starch, enzyme-modified starch, Starches such as esterified starch, etherified starch, cationic starch, amphoteric starch, gelatin, casein, soybean protein, water-soluble polymers such as polyvinyl alcohol, vinyl acetate, ethylene vinyl acetate, polyurethane resin, acrylic resin, Examples include synthetic resins such as polyester resins and polyamide resins. The blending ratio of the pigment and adhesive in the pigment coating layer is not particularly limited, but it is preferably 5 to 50 parts by weight of the adhesive to 100 parts by weight of the pigment. For example, as the adhesive, a combination of 1 to 5 parts by mass of phosphoric acid ester starch and 5 to 15 parts by mass of styrene-butadiene latex can be used with respect to 100 parts by mass of pigment. The pigment coating layer may contain various auxiliary agents as long as they do not impair the desired effects of the present invention, such as viscosity modifiers, softeners, gloss-imparting agents, water-resistant agents, dispersants, and flow modifiers. , an ultraviolet absorber, a stabilizer, an antistatic agent, a crosslinking agent, a sizing agent, an optical brightener, a coloring agent, a pH adjuster, an antifoaming agent, a plasticizer, and a preservative. Further, the coating amount of such a pigment coating layer is, for example, 2 to 40 g/m ² in terms of solid content per one side of the paper base material. In one embodiment of the base paper for paper cups of the present invention, the heat-sealing layer may be provided on such a pigment coating layer, and in another embodiment, the heat sealing layer may be provided on only one side. A heat-sealing layer may be provided on the surface of the paper base material provided with the coating layer on which the pigment coating layer is not provided.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Further, "parts" and "%" in the examples indicate "parts by mass" and "% by mass", respectively, unless otherwise specified. Note that the number of parts added is a value in terms of solid content.

(Example 1)
(Preparation of paper base material)
100 parts of Canadian Standard Freeness 400mlcsf bleached hardwood kraft pulp, 5 parts of light calcium carbonate (product name: TP-123, manufactured by Okutama Kogyo Co., Ltd.), 0.2 parts of cationized starch (product name: Neotac 40T, manufactured by Nihon Shokuhin Kogyo Co., Ltd.) A paper stock was prepared by adding water to 0.5 parts of neutral rosin size (trade name: Harsize AN-300, manufactured by Harima Kasei Co., Ltd.), and using a fourdrinier multi-tube paper machine, the basis weight was 193 g/ A base paper of m ² was produced. Oxidized starch (trade name: SK-20, manufactured by Nippon Cornstarch Co., Ltd.) was applied to this base paper using a gate roll coater so that the dry coating amount per both sides was 2 g/m ² , and after drying, the coating amount was 195 g/m ² . A paper base material was obtained.

(Preparation of base paper for paper cups)
Aqueous ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Chemicals, composition: metal salt of ethylene methacrylic acid copolymer, self-emulsifying emulsion, Microtrack method) was applied to one side of the paper base material obtained above. For ^paper cups with a basis weight of 200 g/m ² A base paper was prepared. The moisture content was adjusted to 5%.

(Example 2)
A base paper for a paper cup was produced in the same manner as in Example 1, except that 100 parts of unbleached softwood kraft pulp was used as the pulp.

(Example 3)
A base paper for a paper cup was produced in the same manner as in Example 1 except that the pulp was 40 parts of softwood kraft pulp and 60 parts of hardwood kraft pulp.

(Example 4)
A base paper for a paper cup was produced in the same manner as in Example 1, except that the amount of cationic starch added was 0.8 parts.

(Example 5)
A base paper for a paper cup was produced in the same manner as in Example 1 except that the Canadian Standard Freeness was changed to 600 cc.

(Example 6)
As the paper base material, the same paper stock as in Example 1 was prepared, and using a circular mesh paper machine, the first layer was 80 g/m ² , the second layer was 130 g/m ² , and the third layer was 83 g/m ² . A base paper for a paper cup was produced in the same manner as in Example 1, except that a paper base material having a basis weight of 293 g/m ² was produced by layer papermaking, and a base paper for a paper cup having a basis weight of 300 g/m ² was produced.

(Example 7)
A paper cup base paper was produced in the same manner as in Example 1 except that the water content of the paper cup base paper was 2.5%.

(Comparative example 1)
Low-density polyethylene (manufactured by Tosoh Corporation, Petrocene DLZ19A) was laminated on one side of the paper base material produced in Example 1 using an extrusion coater (melt extrusion machine) so that the coating amount was 30 g/ ^m2 . A heat-sealing layer was provided, and a base paper for a paper cup was produced.

(Comparative example 2)
In the production of the paper base material of Example 1, 100 parts of Canadian Standard Freeness 250mlcsf bleached softwood kraft pulp, 5 parts of light calcium carbonate (trade name: TP-123, manufactured by Okutama Kogyo Co., Ltd.), and cationized starch (trade name: Neotac) were added. 30T, manufactured by Nippon Shokuhin Kogyo Co., Ltd.) and 0.5 parts of neutral rosin size (product name: Hersize AN-300, manufactured by Harima Kasei Co., Ltd.) to prepare paper stock. A base paper having a basis weight of 428 g/m ² was produced using a tube paper machine. Oxidized starch (trade name: SK-20, manufactured by Nippon Cornstarch Co., Ltd.) was coated on this base paper using a gate roll coater so that the dry coating amount per both sides was 2 g/m ² , and when it was dried, the coating amount was 430 g/m ² . A base paper for a paper cup was produced in the same manner as in Example 1, except that the paper base material was produced, and a base paper for a paper cup with a basis weight of 437 g/m ² was produced.

The base paper for paper cups obtained in each Example and Comparative Example was evaluated by the method shown below. The results obtained are shown in Table 1.

Moisture was measured in accordance with JIS P8127.

(2) Lateral Taber bending resistance Measured in accordance with JIS P-8125-2.

(3) Tensile elongation at break in the longitudinal direction Measured in accordance with JIS P-8113.

(4) Heat-sealing strength Cut the obtained base paper for paper cups into two pieces with a width of 8 mm and a length of 15 cm, and overlap the front and back sides of the base paper for paper cups. Model number: PTS-100) under certain conditions (adhesion width: 4 mm, temperature: 180° C., pressure 0.4 MPa, pressing time 0.5 seconds, pitch: 4 mm). Next, the peel strength of the heat-sealed sample was measured using a peel strength tester (manufactured by Shimadzu Corporation, model number: Autograph AGS-X) under certain conditions (peel speed: 100 mm/min, peel length: 10 cm). The heat seal strength was determined as gf/4 mm. The higher the number, the better.

(5) Paper cup processability 1 (cracks in top processing)
Paper cups were manufactured at a rate of 100 pieces/min using a paper cup manufacturing machine (adhesion was by heat sealing). Cracks in the top curl portion were visually inspected and evaluated as follows.
◎: No cracks at all, practical.
○: Slight cracking, but practical.
△: There are cracks and it cannot be put to practical use.
×: Cracks are extremely noticeable and cannot be put to practical use.

(6) Paper cup processability 2 (side adhesion)
Paper cups were manufactured at a rate of 100 pieces/min using a paper cup manufacturing machine (adhesion was by heat sealing). Adhesiveness of the side adhesive portion was visually confirmed and evaluated as follows.
◎: Completely adhered and practical.
○: Adhesiveness is slightly poor in some parts, but it is practical.
△: There was peeling and it was not practical.
×: Severe peeling, impractical.

In Examples 1 to 7 of the present invention, base papers for paper cups were obtained that reduced the amount of plastic used and had heat sealability and top curl processing suitability on the same level as polylaminated products. In contrast, when a paper base material with a large basis weight was used, sufficient side adhesion was not obtained due to the high Taber bending resistance in the lateral direction (Comparative Example 2).

Claims (5)

A paper cup base paper having at least one heat seal layer on at least one surface of a paper base material, wherein the heat seal layer contains an ionomer, and the dry coating amount of the heat seal layer is 2 in all layers. ~10 g/m ² , the basis weight of the base paper for paper cups is 80 g/m ² ~ 400 g/m ² , and the Taber bending resistance (JIS P-8125-2) in the lateral direction of the base paper for paper cups is 1 mN·m to 10 mN·m , and the water content of the paper cup base paper is 3% to 10% . The basis weight of the base paper for paper cups is 180g/m ² ～300g/m ² The base paper for paper cups according to claim 1, characterized in that: The base paper for paper cups according to claim 1 or 2, wherein the base paper for paper cups has a specific volume of 0.8 to 1.8 cm ³ /g.
The paper base material is mainly composed of pulp, and the freeness of the pulp is 350 to 420 ml CSF according to Canadian standard freeness (JIS P 8121:1995 "Pulp freeness test method"). The base paper for paper cups according to any one of claims 1 to 3 , characterized in that: The paper base material has pulp as a main component, and contains only softwood pulp as the pulp, or contains 50 to 95 parts by mass of softwood pulp and 5 to 50 parts by mass of hardwood pulp, out of the total pulp, The base paper for paper cups according to any one of claims 1 to 4.