Heat-sealing water-dispersible paper and heat-sealing water-dispersible bag

Abstract

The problem addressed by this invention is to provide heat-sealing water-dispersible paper having good water dispersibility and a heat-sealing water-dispersible bag capable of quickly discharging what is included therein into water and hardly causing troubles such as clogging of piping when draining water. Provided are: heat-sealing water-dispersible paper having water-dispersible paper and a thermoplastic resin layer on at least one surface of the water-dispersible paper, the aqueous dispersion flocculation time thereof being less than 20 seconds; and a heat-sealing water-dispersible bag that uses said heat-sealing water-dispersible paper.

Description

Heat-sealable water-dispersible paper and heat-sealable water-dispersible bags

[0001] The present invention relates to a heat-sealable water-dispersible paper and a heat-sealable water-dispersible bag using the heat-sealable water-dispersible paper.

[0002] As a water-dispersible paper having heat-sealing properties, a water-soluble paper having a heat-sealing layer formed thereon has been disclosed (Patent Document 1).

[0003] Japanese Patent Application Publication No. 5-328803

[0004] In a package such as that described in Patent Document 1, in which an inclusion such as a powder detergent is sealed in a bag made of heat-sealable water-dispersible paper, the water-dispersibility is reduced by the influence of the heat-seal layer formed on the water-soluble paper, and therefore, when the package is placed in water, it takes a long time for the bag to break and the inclusion to disperse into the water, resulting in poor efficiency of cleaning and other operations, or, when dispersed in water, clumps of paper pieces (flocs) remain, which can cause problems such as clogging pipes when draining. An object of the present invention is to provide heat-sealable water-dispersible paper with good water-dispersibility and a heat-sealable water-dispersible bag made of this heat-sealable water-dispersible paper.

[0005] [1] A heat-sealable water-dispersible paper having a water-dispersible paper and a thermoplastic resin layer on at least one surface of the water-dispersible paper, the heat-sealable water-dispersible paper having a flocculent water-dispersible time of less than 20 seconds. [2] The heat-sealable water-dispersible paper according to [1], having a fibrous water-dispersible time of less than 40 seconds. [3] The heat-sealable water-dispersible paper according to [1] or [2], wherein the thermoplastic resin layer contains at least one selected from the group consisting of polyvinyl alcohol, starch acetate ester, vinyl acetate-acrylic resin, and butenediol vinyl alcohol, and the polyvinyl alcohol and butenediol vinyl alcohol have a saponification degree of 70 to 99 mol% and a viscosity of a 4% aqueous solution of less than 20 mPa·s. [4] A method for producing the heat-sealable water-dispersible paper according to [1] or [2], wherein the thermoplastic resin layer is formed by applying a coating liquid containing a thermoplastic resin by a gravure or flexographic method. [5] A heat-sealable water-dispersible bag using the heat-sealable water-dispersible paper according to [1] or [2]. [6] A method for producing the heat-sealable water-dispersible paper according to [3], characterized in that a thermoplastic resin layer is formed by applying a coating liquid containing a thermoplastic resin by a gravure method or a flexographic method. [7] A heat-sealable water-dispersible bag using the heat-sealable water-dispersible paper according to [3]. [8] The heat-sealable water-dispersible paper according to any one of [1] to [3], which has the thermoplastic resin layer partially formed on the water-dispersible paper. [9] The heat-sealable water-dispersible paper according to [8], in which the thermoplastic resin layer is surrounded by an area where the thermoplastic resin layer is not formed.

[10] The heat-sealable water-dispersible paper according to [9], in which the maximum width of the area where the thermoplastic resin layer is not formed is 0.1 mm or more and 5 mm or less.

[11] A heat-sealable water-dispersible bag using the heat-sealable water-dispersible paper according to any one of [8] to

[10] .

[0006] The heat-sealable water-dispersible paper and heat-sealable water-dispersible bag of the present invention have good heat-sealability and water-dispersibility, and can quickly release the contents into water. Furthermore, because the contents quickly disperse into flocs or fibers in water, clogging of pipes during drainage is unlikely to occur.

[0007] <Heat-sealable water-dispersible paper> The heat-sealable water-dispersible paper of the present invention is a heat-sealable water-dispersible paper having a water-dispersible paper and a thermoplastic resin layer on at least one surface of the water-dispersible paper, and having a flocculent water dispersion time of less than 20 seconds. The heat-sealable water-dispersible paper of the present invention is provided with heat-sealability by this thermoplastic resin layer.

[0008] <Water-Dispersible Paper> In the present invention, water-dispersible paper refers to paper having a flocculated water dispersion time of less than 20 seconds or a fibrous water dispersion time of less than 40 seconds. The flocculated water dispersion time is the time it takes for a 3 cm square test piece to break into two or more pieces when 300 ml of deionized water is placed in a 300 ml beaker and stirred at 650 rpm with a stirrer. The fibrous water dispersion time is the time it takes for a 3 cm square test piece to break into two or more pieces when 300 ml of deionized water is placed in a 300 ml beaker and stirred at 650 rpm with a stirrer and a 3 cm square test piece to disperse into fibers (flocs become invisible). It is more preferable that the water-dispersibility of water-dispersible paper is such that the flocculated water dispersion time is less than 10 seconds or the fibrous water dispersion time is less than 20 seconds. The water-dispersible paper can be any paper that satisfies the above-mentioned floc-like water dispersion time, without any particular limitation. For example, water-dispersible paper described in Japanese Patent No. 6010461 containing 15% by weight to 95% by weight of purified pulp based on the total pulp, water-dispersible paper obtained by impregnating or coating this with a water-soluble polymer, and base paper for water-peelable coated paper described in Japanese Patent No. 4917274 containing water-dispersible fiber and a water-soluble fiber, a carboxyalkyl cellulose salt, can be used.

[0009] The basis weight of the water-dispersible paper is 10 g / m ２ More than 100g / m ２ The following range is preferred: 20 g / m ２ 80g / m or more ２ It is more preferable that the basis weight is 10 g / m or less. ２ If the basis weight is less than 100 g / m, the strength may be insufficient. ２ If the particle size is larger, the pulp fibers that are produced when the water-dispersible paper is dispersed may make it difficult for the encapsulated substances to be released into water.

[0010] <Papermaking> As a papermaking machine for producing water-dispersible paper, any of a Fourdrinier papermaking machine, a cylinder papermaking machine, an inclined short-wire papermaking machine, a twin-wire papermaking machine, etc. can be used. Furthermore, papermaking is carried out using either a neutral papermaking method or an alkaline papermaking method. Furthermore, internal papermaking aids such as aluminum sulfate and various anionic, cationic, nonionic, or amphoteric retention aids, drainage aids, and paper strength agents can be added as needed. Furthermore, papermaking additives such as pH adjusters, antifoaming agents, pitch control agents, and slime control agents can be added as needed.

[0011] <Additional processing of water-dispersible paper> The water-dispersible paper used in the present invention can be subjected to calendering using a general papermaking calender such as a machine calender, super calender, or soft nip calender in order to improve the smoothness and provide it for printing applications, etc.

[0012] <Thermoplastic Resin> In the heat-sealable water-dispersible paper of the present invention, the thermoplastic resin used in the thermoplastic resin layer is preferably a water-soluble heat-sealing agent, and more preferably a heat-sealing agent that is water-soluble in cold water at 20°C. Examples of suitable heat-sealing agents include vinyl acetate / acrylic heat-sealing agents, vinyl acetate / acrylic heat-sealing agents, acrylic / wax heat-sealing agents, polyvinyl alcohol heat-sealing agents, starch-based heat-sealing agents, olefin-based heat-sealing agents, and butenediol vinyl alcohol heat-sealing agents. Since the heat-sealable water-dispersible paper of the present invention is made of water-dispersible paper, applying a heat-sealing agent with a high moisture content will cause the water-dispersible paper to become swollen due to the water contained in the heat-sealing agent. Furthermore, water-soluble heat-sealing agents are required to dissolve and disperse quickly upon contact with water. Among the heat-sealing agents listed above, vinyl acetate / acrylic heat-sealing agents, polyvinyl alcohol heat-sealing agents, starch-based heat-sealing agents, olefin-based heat-sealing agents, and butenediol vinyl alcohol heat-sealing agents are preferred because they can be applied at high concentrations and have excellent water-dispersibility after drying. These heat sealing agents may also be used in combination. Furthermore, butenediol vinyl alcohol-based heat sealing agents are preferred in view of their excellent storage stability.

[0013] <Polyvinyl Alcohol> Polyvinyl alcohol is produced by polymerizing vinyl acetate monomer and substituting hydroxyl groups for the acetate groups of the resulting polyvinyl acetate (saponification). The degree of saponification is a value indicating the proportion of substituted hydroxyl groups and is calculated using the following formula (1): (Formula 1) Degree of saponification (mol %) = (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups) × 100. The lower the degree of saponification of polyvinyl alcohol, the higher its water solubility and thermoplasticity. The degree of saponification of polyvinyl alcohol used as the thermoplastic resin layer of the present invention is preferably 70 to 99 mol %. Furthermore, the lower the degree of polymerization of polyvinyl alcohol, the lower the aqueous solution viscosity and the higher its water solubility and thermoplasticity. However, the viscosity of a 4% aqueous solution of polyvinyl alcohol used as the thermoplastic resin layer of the present invention is preferably less than 20 mPa·s.

[0014] Butenediol vinyl alcohol is produced by polymerizing 1,4-diacetoxy-2-butene monomer and substituting hydroxyl groups for the acetate groups of the resulting polymer (saponification). The degree of saponification is a value indicating the proportion of substituted hydroxyl groups and is calculated using the above formula (1). As with polyvinyl alcohol, the lower the degree of saponification of butenediol vinyl alcohol, the higher the water solubility and thermoplasticity. The degree of saponification of butenediol vinyl alcohol used in the thermoplastic resin layer of the present invention is preferably 70 to 99 mol%. Furthermore, the lower the degree of polymerization of butenediol vinyl alcohol, the lower the aqueous solution viscosity and the higher the water solubility and thermoplasticity. However, the viscosity of a 4% aqueous solution of butenediol vinyl alcohol used in the thermoplastic resin layer of the present invention is preferably less than 20 mPa·s.

[0015] <Formation of Thermoplastic Resin Layer> The heat-sealable water-dispersible paper of the present invention has a thermoplastic resin layer formed on at least one surface of the water-dispersible paper. The thermoplastic resin layer may be formed on both sides of the water-dispersible paper, or may be formed by laminating multiple thermoplastic resin layers. The thermoplastic resin layer may be formed over the entire surface or partially. The thermoplastic resin layer may be either a coated layer or a laminate layer, but is preferably a coated layer from the viewpoint of production efficiency. When the thermoplastic resin layer is a coated layer, it may be either an aqueous coating using a solvent such as water or a solvent-based coating using a solvent such as an organic solvent, but is preferably an aqueous coating from the viewpoint of safety and hygiene. When using aqueous coating, it is preferable to use an aqueous dispersion of a thermoplastic resin or a water-soluble thermoplastic resin.

[0016] The method for applying the thermoplastic resin layer is not particularly limited, and the layer can be formed using a known coating device. However, a gravure coater or a flexo coater is preferred because it is a method in which a specified amount to be applied is measured using an embossed pattern on a gravure roll, and the coating liquid is either transferred directly to the substrate and applied thereto, or the coating liquid is first transferred to a coating roll and then applied to the substrate, allowing the coating layer to be formed only on the surface of the substrate.

[0017] Furthermore, when coating is performed using a gravure coater, flexo coater, or the like, the viscosity of the coating liquid (B-type viscosity, No. 3 rotor, 60 rpm) is preferably 30 to 1500 mPa·s, more preferably 50 to 1000 mPa·s, and even more preferably 100 to 500 mPa·s. If the viscosity of the coating liquid is within the above range, the coating liquid transferred using a gravure coater or the like is unlikely to penetrate into the interior of even a substrate with good water absorption, and remains on the surface of the substrate, making it possible to obtain sufficient heat seal strength even with a small amount of attached heat seal layer.

[0018] The method for partially forming the thermoplastic resin is not particularly limited, and it can be formed using a known coating device, but it is preferable to use a gravure coater, a screen printing machine, or the like.

[0019] The amount of thermoplastic resin deposited on the heat-sealable water-dispersible paper of the present invention is 0.5 to 20 g / m when converted per area of ​​the region where the thermoplastic resin layer is formed. ２ is desirable, and 1 to 10 g / m ２ The amount of thermoplastic resin applied is more preferably 0.5 g / m ２ If the amount of the thermoplastic resin applied is less than 20 g / m, sufficient heat sealing properties cannot be obtained. ２ If the applied amount of the thermoplastic resin exceeds 3 to 20 g / m, the drying load in the forming step of the thermoplastic resin increases, which leads to poor productivity and is also disadvantageous in terms of cost. ２ is more desirable.

[0020] When the thermoplastic resin layer is partially formed, the thermoplastic resin layer may be surrounded by a portion where the thermoplastic resin layer is not formed. The maximum width of the portion where the thermoplastic resin layer is not formed is preferably 0.1 mm or more and 5 mm or less. If the maximum width of the portion where the thermoplastic resin is not formed is less than 0.1 mm, the effect of improving water dispersibility due to the portion where the thermoplastic resin is not formed may be reduced, and if it exceeds 5 mm, the powder detergent may leak from the heat-sealed portion when it is sealed in a heat-sealable water-dispersible bag. The maximum width of the portion where the thermoplastic resin layer is not formed is more preferably 0.5 mm or more and 4 mm or less.

[0021] The shape of the thermoplastic resin layer surrounded by the portion where the thermoplastic resin layer is not formed is not particularly limited. For example, the portion where the thermoplastic resin layer is not formed can be formed in a lattice shape, with the interior of the lattice being the thermoplastic resin layer. By forming the thermoplastic resin layer and the portion where the thermoplastic resin layer is not formed in a lattice shape, the portion where the thermoplastic resin layer is not formed can be continuously formed, thereby improving the water dispersibility of heat-sealable water-dispersible papermaking. Furthermore, as a shape where the thermoplastic resin layer is partially formed, dot-shaped portions where the thermoplastic resin layer is not formed can be formed in the region where the thermoplastic resin layer is formed. The dot shape may be circular, elliptical, or other shape. In the case of a circle, the diameter is the maximum width of the portion where the thermoplastic resin layer is not formed, and in the case of an ellipse, the major axis is the maximum width of the portion where the thermoplastic resin layer is not formed.

[0022] Furthermore, the ratio of the area where the thermoplastic resin layer is formed on the water-dispersible paper to the area where the thermoplastic resin layer is not formed is preferably 30% to 80% and more preferably 40% to 70% of the entire surface of the water-dispersible paper. By setting the ratio of the thermoplastic resin layer within this range, the water dispersion time and bag breakage time of the produced heat-sealable water-dispersible bag can be set within appropriate ranges.

[0023] The heat-sealable water-dispersible paper thus formed has a flocculated water-dispersion time of less than 20 seconds. The flocculated water-dispersion time is preferably less than 10 seconds. The heat-sealable water-dispersible paper preferably has a fibrous water-dispersion time of less than 40 seconds. The fibrous water-dispersion time is more preferably less than 20 seconds. The flocculated water-dispersion time and the fibrous water-dispersion time can be shortened by reducing the area of ​​the thermoplastic resin layer provided on the water-dispersible paper. The time can also be adjusted by selecting the type of thermoplastic resin or increasing or decreasing the amount of thermoplastic resin applied.

[0024] <Coating Solution Auxiliaries> Examples of various coating solution auxiliaries include sizing agents, dry strength agents, wet strength agents, dyes, antifoaming agents, etc., and these can be appropriately selected and used as needed. Furthermore, by adding alcohols such as ethanol and isopropyl alcohol to the coating solution, it is possible to suppress a decrease in the strength of the water-dispersible paper during coating and also improve its processing suitability.

[0025] <Heat-sealing property> The heat-sealable water-dispersible paper of the present invention has heat-sealing property that allows it to be formed into a bag shape capable of holding contents. The heat-sealable water-dispersible paper of the present invention has a heat-sealing strength of 0.098 N / 15 mm or more when heat-sealed at a temperature of 160°C, a pressure of 294 kPa, and a time of 1 second, and peeled at a tensile speed of 300 mm / min using a T-type seal. This heat-sealing strength is preferably 0.98 N / 15 mm or more, more preferably 1.96 N / 15 mm or more, and even more preferably 2.94 N / 15 mm or more.

[0026] <Heat-sealable Water-Dispersion Bag> The heat-sealable water-dispersion bag of the present invention is made from the heat-sealable water-dispersion paper described above. The shape of the heat-sealable water-dispersion bag of the present invention (hereinafter sometimes simply referred to as "water-dispersion bag") is not particularly limited as long as it can hold the contents inside. For example, it can be a three-sided sealed bag made by folding the heat-sealable water-dispersion paper in half with the heat-sealed side facing inward and heat-sealing three sides together; a four-sided sealed bag made by aligning the heat-sealed sides of two sheets of heat-sealable water-dispersion paper and heat-sealing the outer periphery; or a pillow-shaped bag made by sealing two sheets of heat-sealable water-dispersion paper in a cylindrical state with the heat-sealed sides facing each other, sealing the bottom, and cutting to a specified length. Pillow-shaped bags can be vertical pillow packaging bags or horizontal pillow packaging bags. Other shapes of the water-dispersion bag include side-sealed bags, two-sided sealed bags, gusset bags, bottom gusset bags, and stand-up bags. In order to quickly release the contents into water, the water-dispersible bag used in the present invention preferably has a rupture time of less than 60 seconds when the contents are sealed inside and the bag is placed in water, more preferably less than 30 seconds, and even more preferably less than 20 seconds.

[0027] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0028] Experimental Example 1 Example 1 Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２ A 20% aqueous solution of isopropyl alcohol (viscosity 1150 mPa s) containing 20% ​​polyvinyl alcohol (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., JR-05) with a saponification degree of 70 to 74 mol% and a 4% aqueous solution viscosity of 5.5 mPa s was applied to one side of a 95-mesh, 51 cm cell volume substrate. ３ / m ２ The mixture was applied using a gravure roll and then dried to obtain a heat-sealable water-dispersible paper of Example 1.

[0029] Example 2: Gravure roll: 120 mesh, cell volume: 32 cm ３ / m ２ A heat-sealable water-dispersible paper of Example 2 was obtained in the same manner as in Example 1, except that the following was used:

[0030] Example 3: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２ A 15% solids aqueous solution (viscosity 480 mPa s) of polyvinyl alcohol (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., JR-05) with a saponification degree of 70 to 74 mol% and a 4% aqueous solution viscosity of 5.5 mPa s was used as a coating solution on one side of a 110-mesh, 40 cm cell volume sieve. ３ / m ２ The mixture was applied using a gravure roll and then dried to obtain a heat-sealable water-dispersible paper of Example 3.

[0031] Example 4: Water-dispersible paper with a basis weight of 60 g / m ２ (Nippon Paper Papylia Co., Ltd., 60MDP, basis weight: 60g / m ２ A heat-sealable water-dispersible paper of Example 4 was obtained in the same manner as in Example 1, except that a flocculant having a thickness of 110 μm, a flocculant water-dispersion time of 4 seconds, and a fibrous water-dispersion time of 12 seconds was used.

[0032] Example 5 A heat-sealable water-dispersible paper of Example 5 was obtained in the same manner as in Example 1, except that a 30% solids aqueous solution (viscosity 200 mPa s) of polyvinyl alcohol (manufactured by Mitsubishi Chemical Corporation, L3266) with a saponification degree of 86.5 to 89 mol % and a 4% aqueous solution viscosity of 3 mPa s was used as the coating liquid.

[0033] Example 6 A heat-sealable water-dispersible paper of Example 6 was obtained in the same manner as in Example 1, except that a 20% solids aqueous solution (viscosity 1090 mPa s) of polyvinyl alcohol (3-98, manufactured by Kuraray Co., Ltd.) with a saponification degree of 98 to 99 mol % and a 4% aqueous solution viscosity of 3.5 mPa s was used as the coating liquid.

[0034] Example 7 A heat-sealable water-dispersible paper of Example 7 was obtained in the same manner as in Example 6, except that a 25% solids aqueous solution (viscosity 880 mPa s) of starch acetate (Z-P8, manufactured by Nippon Starch Chemical Co., Ltd.) was used as the coating liquid.

[0035] Example 8: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２ A coating solution of 28% solids concentration (viscosity 700 mPa s) obtained by adding 70 parts by mass of vinyl acetate / acrylic heat sealing agent (HW-21 manufactured by Resonac Corporation) to 30 parts by mass of isopropyl alcohol was applied to one side of a 180 mesh, 18 cm cell volume. ３ / m ２ The mixture was applied using a gravure roll and then dried to obtain a heat-sealable water-dispersible paper of Example 8.

[0036] Example 9: Gravure roll: 110 mesh, cell volume: 40 cm ３ / m ２ A heat-sealable water-dispersible paper of Example 9 was obtained in the same manner as in Example 8, except that the following was used:

[0037] Example 10: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 60CD10-S, basis weight: 60 g / m ２A 15% solids aqueous solution (viscosity 480 mPa s) of polyvinyl alcohol (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., JR-05) with a saponification degree of 70 to 74 mol% and a 4% aqueous solution viscosity of 5.5 mPa s was used as a coating solution on one side of a 95-mesh, cell volume 51 cm3 PET film (78 μm thick, floc-like water dispersion time: 7 seconds, fibrous water dispersion time: more than 180 seconds). ３ / m ２ The mixture was applied using a gravure roll and then dried to obtain a heat-sealable water-dispersible paper of Example 10.

[0038] Example 11 A heat-sealable water-dispersible paper of Example 11 was obtained in the same manner as in Example 1, except that a 20% solids aqueous solution (viscosity 1270 mPa s) of polyvinyl alcohol (5-98, manufactured by Kuraray Co., Ltd.) having a saponification degree of 98 to 99 mol % and a 4% aqueous solution viscosity of 5.6 mPa s was used as the coating liquid.

[0039] Comparative Example 1 A heat-sealable water-dispersible paper of Comparative Example 1 was obtained in the same manner as in Example 1, except that a 10% solids aqueous solution (viscosity 3320 mPa s) of polyvinyl alcohol (28-98, manufactured by Kuraray Co., Ltd.) with a saponification degree of 98 to 99 mol % and a 4% aqueous solution viscosity of 28 mPa s was used as the coating liquid.

[0040] Comparative Example 2 A heat-sealable water-dispersible paper of Comparative Example 2 was obtained in the same manner as in Example 9, except that the coating liquid was applied using a wire bar with a winding diameter of 0.1 mm.

[0041] Example 12: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２ , thickness 44 μm, flocculated water dispersion time: 5 seconds, fibrous water dispersion time: 10 seconds) was coated on one side with an olefin-based heat sealing agent (Mitsui Chemicals, Chemipearl S500NW, solid content concentration 42%, viscosity 150 mPa s) as a coating liquid. ３ / m ２ The mixture was applied using a gravure roll and then dried to obtain a heat-sealable water-dispersible paper of Example 12.

[0042] Example 13: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２A 22% solids aqueous solution (viscosity 170 mPa s) of butenediol vinyl alcohol (manufactured by Mitsubishi Chemical, Nichigo Polymer AZF8035Q) with a saponification degree of 98 mol% and a 4% aqueous solution viscosity of 3.0 mPa s was applied to one side of a 150-mesh, 25 cm cell. ３ / m ２ The mixture was applied using a gravure roll and then dried to obtain a heat-sealable water-dispersible paper of Example 13.

[0043] Example 14: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２ A 20% solids aqueous solution (viscosity 160 mPa s) of butenediol vinyl alcohol (manufactured by Mitsubishi Chemical, Nichigo Polymer AZF8035Q) with a saponification degree of 98 mol% and a 4% aqueous solution viscosity of 3.0 mPa s was applied to one side of a 180-mesh, 18 cm cell volume substrate (44 μm thick, floc-like water dispersion time: 5 seconds, fibrous water dispersion time: 10 seconds). ３ / m ２ The mixture was applied using a gravure roll and then dried to obtain a heat-sealable water-dispersible paper of Example 14.

[0044] Example 15: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 60MDP, basis weight: 60 g / m ２ A 22% solids aqueous solution (viscosity 170 mPa s) of butenediol vinyl alcohol (manufactured by Mitsubishi Chemical, Nichigo Polymer AZF8035Q) with a saponification degree of 98 mol% and a 4% aqueous solution viscosity of 3.0 mPa s was applied to one side of a 150-mesh, 25 cm cell (thickness 110 μm, floc-like water dispersion time: 4 seconds, fibrous water dispersion time 12 seconds). ３ / m ２ The mixture was applied using a gravure roll and then dried to obtain a heat-sealable water-dispersible paper of Example 15.

[0045] Evaluation Items and Evaluation Methods The following evaluations were carried out on the obtained heat-sealable water-dispersible sheets. The results are shown in Tables 1 and 2. For Examples 14 and 15, evaluation was also carried out after treatment for 24 hours under conditions of a temperature of 60°C and a humidity of 80% RH. The results are shown in Table 3. <Basis Weight, Adhesion Amount> Basis weight was measured in accordance with JIS P8124. Adhesion amount was defined as the difference between the basis weight of the heat-sealable water-dispersible paper coated with a heat-sealing agent and the basis weight of the uncoated water-dispersible paper.

[0046] <Floc-like water dispersion time> 300 ml of deionized water was placed in a 300 ml beaker, and while stirring with a stirrer at 650 rpm, a 3 cm square test piece was added, and the time until the test piece broke into two or more pieces was measured. Measurements were made with N=3, and the average value was taken as the floc-like water dispersion time.

[0047] <Fiber-like water dispersion time> 300 ml of deionized water was placed in a 300 ml beaker, and while stirring with a stirrer at 650 rpm, a 3 cm square test piece was added, and the time until the test piece dispersed into a fibrous form (flocs became unrecognizable) was measured. Measurements were made with N=3, and the average value was taken as the fiber-like water dispersion time.

[0048] <Heat seal strength> The thermoplastic resin layer surfaces of the heat-sealable water-dispersible paper were placed together, and heat-sealed using a heat seal tester (HEAT SEAL TESTER TP-701S, manufactured by Tester Sangyo Co., Ltd.) at a temperature of 160°C, a pressure of 294 kPa, and a time of 1 second, and then peeled using a universal tensile tester (Tensilon RTG-1210, manufactured by A&D Co., Ltd.) with a test width of 15 mm and a tensile speed of 300 mm / min using a T-type peeler.

[0049] <Bag Breakage Time> A 5 ​​cm x 10 cm test piece was folded in half with the thermoplastic resin layer facing inward, and two sides were heat-sealed together. 3 g of a commercially available powder detergent was then placed inside, and the remaining side was heat-sealed to produce a 5 cm square water-dispersible bag. 300 ml of deionized water was placed in a 300 ml beaker, and the water-dispersible bag was added. The time until the powder detergent was released from the water-dispersible bag into the water was measured. Measurements were performed twice, and the average value was taken as the bag breakage time.

[0050] <Drainage> 300 ml of deionized water was placed in a 300 ml beaker, and while stirring with a stirrer at 650 rpm, a 3 cm square test piece was added. Immediately after stirring for 30 seconds, the test liquid was poured onto a sieve with a mesh size of 2.36 mm from a height of 10 cm over 3 seconds, and the presence or absence of sample residue on the sieve was confirmed. If residue was confirmed on the sieve, 300 ml of deionized water was poured from a height of 10 cm over 3 seconds so that the deionized water would hit the residue, to rinse the residue, and then the presence or absence of sample residue on the sieve was confirmed. Evaluation of drainage: ◎: No sample residue on the sieve after the test liquid was poured; ○: No sample residue on the sieve after rinsing the residue; ×: Sample residue remains on the sieve even after rinsing the residue

[0051]

[0052]

[0053]

[0054] The heat-sealable water-dispersible papers obtained in Examples 1 to 8 and 13 to 15 of the present invention have excellent heat-sealing properties and disperse quickly into fibers in water, so that when a water-dispersible bag containing an inclusion is placed in water, the bag quickly breaks, and pipe clogging is unlikely to occur during drainage. The heat-sealable water-dispersible papers obtained in Examples 9 to 12 of the present invention have excellent heat-sealing properties and disperse quickly into flocs in water, so that when a water-dispersible bag containing an inclusion is placed in water, the bag quickly breaks, and pipe clogging can be prevented by adding water during drainage. On the other hand, the heat-sealable water-dispersible paper of Comparative Example 1 has insufficient heat-sealing properties, so that the sealed portion easily peels off when the bag is made, making it impossible to maintain the shape of the bag, and also has insufficient dispersibility in water, so that pipe clogging may occur even when adding water during drainage. The heat-sealable water-dispersible paper of Comparative Example 2 had insufficient dispersibility in water, and when the water-dispersible bag containing the inclusions was dropped into water, the bag broke slowly, and even if additional water was poured in when draining, there was a possibility that the pipes would become clogged.

[0055] Furthermore, in Examples 14 and 15, which were treated for 24 hours under conditions of a temperature of 60°C and a humidity of 80% RH, no deterioration due to the treatment was observed in any of the heat seal strength, block-like water dispersion time, fibrous water dispersion time, bag rupture time, and drainage property before and after the treatment. This confirms that the use of butenediol vinyl alcohol as the thermoplastic resin improves storage stability.

[0056] Experimental Example 2 A sample in which a thermoplastic resin layer was partially formed was prepared as Experimental Example 2. As a comparative example, a sample in which a thermoplastic resin layer was formed over the entire surface was prepared.

[0057] Example 16: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30 MDP, basis weight: 30 g / m ２ A coating solution containing 70 parts of a vinyl acetate-acrylic heat sealant (Kogam HW-21, manufactured by Showa Denko K.K.) and 30 parts of isopropyl alcohol was applied to one side of the sheet (65 μm thick, flocculent water dispersion time: 4 seconds) using a 135-mesh screen having 4 mm diameter non-printing areas for the heat sealant at 5 mm intervals, and then dried with a rotary dryer to obtain a heat sealant coating amount of 15 g / m. ２ A heat-sealable water-dispersible paper of 100g was obtained.

[0058] Example 17: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２ The same coating liquid as in Example 1 was applied to one surface of a sheet of paper (flocculant, thickness 44 μm, flocculant water dispersion time: 4 seconds) using a 180-mesh screen having a grid pattern in which 8 mm squares were arranged at 2 mm intervals as the heat-sealing agent printing area, and then dried with a rotary dryer to obtain a heat-sealing agent coating amount of 10 g / m. ２ A heat-sealable water-dispersible paper of 100g was obtained.

[0059] Example 18: Water-dispersible paper with a basis weight of 60 g / m ２ The same procedure as in Example 17 was carried out except that a heat-sealing agent coating amount of 10 g / m was used (manufactured by Nippon Paper Papylia Co., Ltd., 60MDP, floc-like water dispersion time: 4 seconds). ２ A heat-sealable water-dispersible paper of this type was obtained.

[0060] Comparative Example 3: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２ A coating solution containing 70 parts of a vinyl acetate-acrylic heat-sealing agent (Kogam HW-21, manufactured by Showa Denko K.K.) and 30 parts of isopropyl alcohol was applied to one surface of the sheet (thickness: 44 μm, flocculent water dispersion time: 4 seconds) using a wire bar with a wire diameter of 0.15 mm, and then dried with a rotary dryer to obtain a coating amount of the heat-sealing agent of 10 g / m. ２ A heat-sealable water-dispersible paper of 100g was obtained.

[0061] Example 19: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２ An olefin-based heat-sealing agent (Chemipearl S500NW, manufactured by Mitsui Chemicals) was applied to one side of the sheet (44 μm thick, flocculent water dispersion time: 4 seconds) using a 180-mesh gravure plate with a grid pattern of 2 mm squares spaced at 1 mm intervals as the heat-sealing agent printing area, and then dried with a rotary dryer to leave a heat-sealing agent coating amount of 2.4 g / m. ２ A heat-sealable water-dispersible paper of 100g was obtained.

[0062] Example 20: Water-dispersible paper (manufactured by Nippon Paper Papylia Co., Ltd., 30MDP-S, basis weight: 30 g / m ２ An aqueous solution of butenediol vinyl alcohol (AZF8035Q, manufactured by Mitsubishi Chemical) with a solid content of 22% was applied to one side of the sheet (thickness: 44 μm, flocculent water dispersion time: 4 seconds) using a 180-mesh gravure plate with a grid pattern of 2 mm squares arranged at 1 mm intervals as the heat-sealing agent printing area, and then dried with a rotary dryer to obtain a heat-sealing agent coating amount of 1.4 g / m. ２ A heat-sealable water-dispersible paper of 100g was obtained.

[0063] The heat-sealable water-dispersible papers obtained in Examples 16 to 20 and Comparative Example 1 were evaluated as follows. The results are shown in Tables 4 and 5. <Flocculated Water Dispersion Time> 300 ml of deionized water was placed in a 300 ml beaker, and while stirring with a stirrer at 650 rpm, a 3 cm square test piece was added, and the time it took for the test piece to break into two or more pieces was measured. Measurements were made with N=3, and the average value was taken as the water dispersion time.

[0064] <Bag Breakage Time> A 5 ​​cm x 10 cm test piece was folded in half with the heat-sealed side facing inward, and two sides were heat-sealed together. 3 g of a commercially available powder detergent was then placed inside, and the remaining side was heat-sealed to produce a 5 cm square water-dispersible bag. 300 ml of deionized water was placed in a 300 ml beaker, and the water-dispersible bag was added. The time until the powder detergent was released from the water-dispersible bag into the water was measured. Measurements were performed twice, and the average value was taken as the bag breakage time.

[0065] <Heat sealability> The heat-sealed surfaces of the test specimens were heat-sealed together using a heat sealer (FS-215, 7 memory, manufactured by Impulse), and cut to a width of 15 mm. The specimens were then pulled by hand to peel off the sealed portions, and the state of peeling and rupture was checked. Evaluation of heat sealability: ○: The heat-sealed portion did not peel off, and the substrate ruptured. △: The heat-sealed portion delaminated. ×: Heat sealing was not possible.

[0066]

[0067]

[0068] The heat-sealable water-dispersible papers produced in Examples 16 to 20 of the present invention were excellent in water dispersibility. Furthermore, the water-dispersible bags produced using Examples 16 to 20 were excellent in terms of bag tearing resistance when placed in water. In particular, the heat-sealable water-dispersible papers and water-dispersible bags produced in Examples 17 to 20 were easily torn when wet with water because the thermoplastic resin layer was surrounded by areas where no thermoplastic resin layer was formed, and thus had superior water dispersibility and bag tearing resistance.

Claims

1. A water-dispersible paper and a heat-sealable water-dispersible paper having a thermoplastic resin layer on at least one surface of the water-dispersible paper, the heat-sealable water-dispersible paper having a floc-like water-dispersing time of less than 20 seconds.

2. The heat-sealable water-dispersible paper according to claim 1, having a fibrous water-dispersing time of less than 40 seconds.

3. The thermoplastic resin layer contains at least one selected from the group consisting of polyvinyl alcohol, acetate esterified starch, vinyl acetate-acrylic resin, and butanediol vinyl alcohol, and the saponification degree of the polyvinyl alcohol and butanediol vinyl alcohol is 70 to 99 mol%, and the viscosity of a 4% aqueous solution is less than 20 mPa·s. The heat-sealable water-dispersible paper according to claim 1 or 2.

4. A method for manufacturing the heat-sealable water-dispersible paper according to claim 1 or 2, characterized in that the thermoplastic resin layer is formed by applying a coating liquid containing a thermoplastic resin by a gravure method or a flexo method.

5. A heat-sealable water-dispersible bag using the heat-sealable water-dispersible paper according to claim 1 or 2.

6. A method for manufacturing the heat-sealable water-dispersible paper according to claim 3, characterized in that the thermoplastic resin layer is formed by applying a coating liquid containing a thermoplastic resin by a gravure method or a flexo method.

7. A heat-sealable water-dispersible bag using the heat-sealable water-dispersible paper according to claim 3.

8. The heat-sealable water-dispersible paper according to claim 1, having the thermoplastic resin layer partially formed on the water-dispersible paper.

9. The heat-sealable water-dispersible paper according to claim 8, wherein the thermoplastic resin layer is surrounded by a portion where the thermoplastic resin layer is not formed.

10. The heat-sealable water-dispersible paper according to claim 9, wherein the maximum width of the portion where the thermoplastic resin layer is not formed is 0.1 mm or more and 5 mm or less.

11. A heat-sealable water-dispersible bag using the heat-sealable water-dispersible paper according to any one of claims 8 to 10.

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