Water-based emulsion moisture-proof coating agent and method for producing paper or paperboard coated with said water-based emulsion moisture-proof coating agent

Abstract

To provide an aqueous emulsion moistureproof coating agent that uses biological components as the main ingredients, thereby offering excellent moisture proofness and carbon neutralness.SOLUTION: An aqueous emulsion moistureproof coating agent contains a rosin (a), a dispersant having an anionic group (b), at least one film-forming aid (c) that has a boiling point at 1 atmospheric pressure being higher than 100°C, and includes in one molecule one or more functional groups selected from a hydroxy group, an ether group and an ester group, and water. A mass ratio of the rosin (a) satisfies a following formula: (a) / (total amount of organic compound in moistureproof coating agent)×100≥70 (%).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous emulsion moisture-proof coating agent that enhances carbon neutrality by using a bio-derived component as a main component, and a moisture-proof paper using the same.

Background Art

[0002] Conventionally, in papers and paperboards that require moisture-proof properties, laminated papers laminated with polyolefin resins such as polyethylene are widely used because they have excellent moisture-proof properties and are inexpensive.

[0003] However, because the strength of the polyolefin resin in the laminated part is high, it is difficult to remove the laminated part from the paper in the repulping process during recycling, and some may remain on the paper base material. For this reason, the paper recycled from this laminated paper has defects on the paper surface due to the fragments of the laminate being incorporated, so it is inferior in appearance and printability, and the polyolefin laminated paper has low recyclability. Moreover, since polyolefin is synthesized from petroleum components, which are fossil fuels, carbon dioxide emissions at the time of disposal accumulate in the atmosphere by the amount of fossil fuel components consumed, resulting in a high environmental load.

[0004] Also, when polyolefin laminated paper is discarded in the environment, the polyolefin part does not biodegrade and remains in the environment for a long time, contributing to environmental destruction.

[0005] As a moisture-proof resin composition that improves recyclability (release property) by resin coating and enhances biodegradability by a coating composed of bio-derived components to reduce the environmental load, there are disclosed a resin composition comprising (a) an aqueous dispersion obtained by blending a polyvalent metal complex salt with a carboxyl group-containing styrene-acrylic copolymer, (b) a styrene-butadiene synthetic rubber latex, (c) an aqueous solution of an alkali-soluble acrylic copolymer, (d) a resin selected from rosin-based, terpene-based, and petroleum-based resins, and (e) a wax emulsion obtained by emulsifying paraffin wax (Patent Document 1), a resin composition containing cellulose ester, shellac, rosin, or cellulose ester, wax, rosin (Patent Document 2), and a paper straw using paper for the base material and rosin for the waterproof layer (Patent Document 3).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

[0007] However, in Patent Document 1, although rosin, a bio-derived component, is contained in the composition solid content at a maximum of 30% by weight, more than 70% by weight of the remainder consists of fossil fuel-derived components such as styrene-acrylic copolymers. Although the possibility of large fragments being incorporated into paper is reduced by finely crushing the resin layer, enhancing the recyclability of waste paper, conversely, the micro-sized resin pieces that were not incorporated into the paper are ultimately discharged out of the papermaking system together with the wastewater, and most are incinerated as paper sludge. Since more than 70% by mass of this resin layer is composed of fossil fuel-derived components, its carbon neutrality was not yet satisfactory. Also, in Patent Document 2, although compounds such as cellulose ester, shellac, and rosin, which are bio-derived components, are used, it is solubilized by using an organic solvent, which is a fossil fuel-derived component, in about 75% to about 80% of the coating liquid, and the carbon neutrality as the coating liquid remains low. In Patent Document 3, by impregnating or coating paper with rosin as an organic solvent solution, the environmental load at the time of paper straw disposal is reduced while enhancing water resistance, but an organic solvent, which is a fossil fuel-derived component, is used in 50 to 75% by mass in the coating liquid, and its carbon neutrality remains low. Also, the moisture-proof property of paper has not been considered at all.

Summary of the Invention

Problems to be Solved by the Invention

[0008] In view of the above circumstances, an object of the present invention is to provide an aqueous emulsion moisture-proof coating agent that is excellent in moisture-proof property and carbon neutrality by using a bio-derived component as a main component.

Means for Solving the Problems

[0009] That is, the present invention is (1) In the aqueous emulsion moisture-proof coating agent, rosins (a) a dispersant (b) having an anionic group At least one film-forming auxiliary agent (c) having a boiling point at 1 atm higher than 100 °C and containing one or more functional groups selected from a hydroxy group, an ether group, and an ester group in one molecule and water containing rosin (a) and having a mass ratio of rosin (a) satisfying the following formula, an aqueous emulsion moisture-proof coating agent (a) / (total amount of organic compounds in the moisture-proof coating agent)×100≧70(%) (2) The film-forming auxiliary agent (c) is triethyl citrate and / or an organic compound having a solubility parameter value of 7 or more and 11 or less, and is contained in a mass ratio of (c) / (a)=2 / 98 to 40 / 60 with respect to rosin (a). The aqueous emulsion moisture-proof coating agent according to (1) above (3) The film-forming auxiliary agent (c) is triethyl citrate, ethyl 3-ethoxypropionate, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol butyl methyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monopropyl ether, 1,2-diacetoxypropane, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether acetate, 3-methoxy-1-butanol, 3-methoxybutyl acetate, 1,3-diacetoxybutane, 1,4-diacetoxybutane, glyceryl triacetate, etc. The aqueous emulsion moisture-proof coating agent according to (1) above, characterized in that it is at least one selected from the group consisting of (4) The aqueous emulsion moisture-proof coating agent according to (1) above, characterized in that at least one of the dispersants (b) is casein (5) Further, the aqueous emulsion moisture-proof coating agent according to (1) above, characterized in that it contains a flat-layered silicate mineral (d) in a mass ratio of (d) / ((a)+(b))=20 / 80 to 75 / 25 with respect to the sum of rosin (a) and the dispersant (b) (6) A method for manufacturing paper or paperboard, characterized by applying the water-based emulsion moisture-proof coating agent according to any one of (1) to (5) above. That's it.

Advantages of the Invention

[0010] According to the present invention, it is possible to obtain a moisture-proof coating agent that is water-based, maintains moisture-proof properties, has a high carbon neutrality because it is mainly composed of rosins which are plant-derived components, and has a low environmental impact.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be specifically described. Note that this embodiment is one form for carrying out the present invention, and the present invention is not limited to such an embodiment. In this specification, parts and % are used, and these are based on mass. Also, the numerical range represented by "~" includes the numerical values described before and after it.

[0012] The moisture-proof coating agent of the present invention contains rosins (a), a dispersant (b) having an anionic group, at least one film-forming aid (c) whose boiling point at 1 atm is higher than 100 °C and contains one or more functional groups selected from a hydroxy group, an ether group, and an ester group in one molecule, and water.

[0013] <Rosins (a)> Rosins (a) refer to raw rosins obtained directly from plants and / or those that have been partially or fully chemically modified such as acid modification or esterification. Furthermore, those in which a part or all of the acid groups contained therein have been neutralized with an alkaline compound are included.

[0014] Specific examples of the rosins (a) include raw rosins such as gum rosin, wood rosin, and tall oil rosin, hydrogenated rosins obtained by adding hydrogen to raw rosins, or modified rosins obtained by subjecting these rosins to an addition reaction with α,β-unsaturated dicarboxylic acids such as maleic acid and fumaric acid. Further examples include rosin esters obtained by esterifying these rosins with hydroxy group-containing compounds such as ethanediol and pentaerythritol. One or a combination of multiple of these can be used. Specific examples of the alkaline compound used for neutralization include ammonia, alkylolamines such as ethanolamine and triethanolamine, alkylalkylolamines such as dimethylethanolamine and methyldiethanolamine, and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. Among these, ammonia is preferred. When ammonia is used, it is easily volatilized from the acid groups during drying of the coating film, and the hydrophobicity of the rosins increases, resulting in excellent moisture-proof properties of the dried coating film.

[0015] In addition, the mass ratio of the rosins (a) contained in the moisture-proof coating agent of the present invention needs to satisfy the following formula. (a) / (total amount of organic compounds in the moisture-proof coating agent)×100≧70(%) When within this range, even when discarded by incineration or the like, due to the carbon neutrality of biomass, it can contribute to reducing the concentration of carbon dioxide in the atmosphere and suppressing the rate of global warming compared to the prior art. The mass ratio is more preferably 80% or more.

[0016] In the present invention, the organic compound refers to a carbon compound excluding simple carbon substances such as graphite and diamond, carbides such as silicon carbide and calcium carbide, oxides such as carbon monoxide and carbon dioxide, sulfides such as carbon disulfide and carbonyl sulfide, nitrides such as carbon nitride, carbonates such as sodium carbonate and calcium carbonate, bicarbonates such as sodium bicarbonate and calcium bicarbonate, cyanates such as hydrogen cyanide, sodium cyanide and potassium cyanide, thiocyanic acid, thiocyanates such as sodium thiocyanate and potassium thiocyanate, halides such as phosgene and carbon tetrachloride, metal carbonyls such as nickel carbonyl and cobalt carbonyl, and metal cyano complexes such as zinc cyano complex and copper cyano complex.

[0017] <Dispersant (b)> Dispersant (b) is a compound containing an anionic group and having an emulsifying ability of rosins (a) and an effect of improving the dispersion stability of the emulsion.

[0018] Dispersants containing an anionic group are roughly classified into anionic dispersants and amphoteric dispersants. Further, each is classified into a synthetic low-molecular dispersant, a synthetic high-molecular dispersant, a natural low-molecular dispersant, a natural high-molecular dispersant, and a modified natural high-molecular dispersant. Specific examples of anionic dispersants include anionic synthetic low-molecular dispersants such as sodium alkylbenzene sulfonate, ammonium alkyl sulfate or sodium dialkyl sulfosuccinate, anionic synthetic high-molecular dispersants such as styrene-acrylic high-molecular dispersants, anionic natural low-molecular dispersants such as surfactin or sophorolipid, and anionic modified natural high-molecular dispersants such as carboxymethyl cellulose, octenyl succinic anhydride-modified starch, and hydroxypropyl xanthan gum. Specific examples of amphoteric dispersants include amphoteric synthetic low-molecular dispersants such as alkyl dimethylaminoacetic acid betaine or sodium alkylaminodiacetate, and amphoteric natural low-molecular dispersants such as lecithin (including hydrogenated products and hydroxides).

[0019] One or more of these can be used in combination. These can be used not only during the emulsification of rosin, but also added after emulsification for the purpose of improving the stability of the emulsion. Also, when the solubility in water is low in its original form, it may be solubilized by adding an alkaline compound such as ammonia, or the liquid containing the dispersant may be heated to increase solubility.

[0020] Among these, from the viewpoints of availability and cost, it is preferably at least one selected from synthetic polymer dispersants and natural polymer dispersants, and more preferably at least one selected from styrene-acrylic polymer dispersants, casein, and lecithin. From the viewpoints of the emulsifying property of rosin, the dispersion stability of the emulsion, and the moisture-proof property of the coating film after drying, it is more preferably casein or lecithin overall, and most preferably casein. The proportion of the dispersant (b) contained in the moisture-proof coating agent is 1 to 10% for synthetic polymers and 3 to 20% for natural polymers with respect to the rosins (a).

[0021] When casein or lecithin is combined with an anionic synthetic low-molecular dispersant or anionic synthetic high-molecular dispersant and used as the dispersant (b), the moisture-proof property of the coating film after drying is further improved. Although the mechanism of the effect manifestation is not clear, it is imagined that the dispersion state of rosin particles in the wet coating film is more strongly stabilized, preventing the localization of the rosin particle distribution due to aggregation and coalescence of rosin particles during heating and drying, and forming a uniform rosin coating film. In this case, the content of casein and / or lecithin with respect to the rosins (a) is 3 to 20%, and the content of the anionic synthetic low-molecular dispersant with respect to the rosins (a) is preferably 1 to 7%. Also, as the anionic synthetic low-molecular dispersant, sodium dialkyl sulfosuccinate is preferred.

[0022] <Film-forming aid (c)> The film-forming aid (c) is a compound having a solubility in water at 25°C of 1 g / 100 g or more, a boiling point at 1 atm higher than 100°C, and containing one or more functional groups selected from hydroxy groups, ether groups, or ester groups in one molecule. For example, alcohols such as 1-butanol (boiling point: 117°C, solubility: 7 g / 100 g), benzyl alcohol (boiling point: 205°C, solubility: 4 g / 100 g), cyclohexanol (boiling point: 161°C, solubility: 4 g / 100 g); glycols such as 1,2-propylene glycol (boiling point: 188°C, solubility: arbitrary), 1,3-butylene glycol (boiling point: 208°C, solubility: arbitrary), dipropylene glycol (boiling point: 230°C, solubility: arbitrary); glycol monoethers such as diethylene glycol monoethyl ether (boiling point: 196°C, solubility: arbitrary), dipropylene glycol monomethyl ether (boiling point: 190°C, solubility: arbitrary), 3-methoxy-1-butanol (boiling point: 161°C, solubility: arbitrary); glycol diethers such as diethylene glycol dimethyl ether (boiling point: 162°C, solubility: arbitrary), diethylene glycol diethyl ether (boiling point: 188°C, solubility: arbitrary), dipropylene glycol dimethyl ether (boiling point: 175°C, solubility: 53 g / 100 g); glycol diesters such as 1,2-diacetoxyethane (boiling point: 190°C, solubility: 18 g / 100 g), 1,2-diacetoxypropane (boiling point: 186°C, solubility: 8 g / 100 g), 1,4-diacetoxybutane (boiling point: 232°C, solubility: 4 g / 100 g); glycol ether esters such as diethylene glycol monoethyl ether acetate (boiling point: 219°C, solubility: arbitrary), propylene glycol monomethyl ether acetate (boiling point: 146°C, solubility: 19 g / 100 g), propylene glycol monomethyl ether propionate (boiling point: 161°C, solubility: 5 g / 100 g); carboxylic acid esters such as ethyl butyrate (boiling point: 121°C, solubility: 1 g / 100 g), butyl lactate (boiling point: 185°C, solubility: 4 g / 100 g), triethyl citrate (boiling point: 294°C, solubility: 6 g / 100 g); glycerin esters such as glyceryl triacetate (boiling point: 258°C, solubility: 7 g / 100 g), etc. One or a combination of plural of these can be used.Since the above compound has a boiling point higher than 100°C, the film-forming aid (c) will evaporate after being concentrated during drying, and the film-forming effect of the film-forming aid (c) will be more likely to be exhibited, so the moisture-proof property of the dried coating film is excellent.

[0023] Among these, from the viewpoint of compatibility with rosins (a), at least one selected from compounds having a solubility parameter value (hereinafter referred to as SP value) calculated by the method described in triethyl citrate and Fedors, R. F., (1974), Polymer Engineering & Science, 14, 147 of 7 or more and 11 or less is preferable, and triethyl citrate, ethyl 3-ethoxypropionate (SP value: 9.2), ethylene glycol monobutyl ether (SP value: 10.8), diethylene glycol monoethyl ether (SP value: 8.2), diethylene glycol monoethyl ether acetate (SP value: 9.2), diethylene glycol dimethyl ether (SP value: 8.1), diethylene glycol diethyl ether (SP value: 8.2), triethylene glycol butyl methyl ether (SP value: 8.4), propylene glycol monomethyl ether acetate (SP value: 8.9), propylene glycol monomethyl ether propionate (SP value: 8.5), propylene glycol mono-n-propyl ether (SP value: 10.7), 1,2-diacetoxypropane (SP value: 9.6), dipropylene glycol monomethyl ether (SP value: 10.4), dipropylene glycol dimethyl ether (SP value: 7.9), dipropylene glycol monomethyl ether acetate (SP value: 8.7), 3-methoxy-1-butanol (SP value: 10.9), 3-methoxybutyl acetate (SP value: 8.7), 1,3-diacetoxybutane (SP value: 9.5), 1,4-diacetoxybutane (SP value: 9.6), glyceryl triacetate (SP value: 10.2) is more preferably at least one. When the film-forming aid (c) is the above compound, since the compatibility with rosins (a) is high, the film-forming effect is easily exhibited and the moisture-proof property of the dried coating film is excellent. At this time, the film-forming aid (c) is preferably contained in a ratio of (c) / (a) = 2 / 98 to 40 / 60 by mass with respect to rosins (a).

[0024] From the perspective of practicality, it is more preferable that it is at least one selected from triethyl citrate, 1,2-acetoxypropane, or glyceryl triacetate, which is a substance generally recognized as safe by the US Food and Drug Administration or an indirect food additive certified as a component of paper and cardboard in contact with food.

[0025] The moisture-proof coating agent of the present invention may further contain a flat-layered silicate mineral (d).

[0026] <Flat-layered silicate mineral (d)> The flat-layered silicate mineral (d) is a layered silicate mineral that is a clay mineral and has an aspect ratio (the ratio of diameter to thickness) exceeding 1. Examples of the layered silicate mineral include kaolin, talc, pyrophyllite, hectorite, montmorillonite, saponite, vermiculite, mica, etc. One or a combination of plural of these can be used. Among these, from the perspective of moisture-proof property, kaolin, montmorillonite, or mica is preferable. Further, by peeling the stacked structure of kaolin or classifying and removing particles of a specific size, engineered kaolin with an average particle size of 5 μm or more and an aspect ratio greater than 10, which is aligned to have a large particle size and a high aspect ratio (aspect ratio: the ratio of the diameter of flat particles to the thickness), is more preferable. Within this range, the moisture-proof property of the dried coating film is excellent. The aspect ratio can be calculated by photographing the flat-layered silicate mineral in the planar direction and the cross-sectional direction with a scanning electron microscope or a transmission electron microscope, measuring its diameter and thickness, and using the formula "aspect ratio = diameter / thickness".

[0027] In addition, the platy layered silicate mineral (d) is preferably contained in a mass ratio of 20 / 80 to 75 / 25 with respect to the total of rosins and / or their alkali neutralized products (a) and the dispersant (b). The combined use of the platy layered silicate mineral can be expected to act as an anti-blocking agent for the coating layer, and in addition to maintaining the moisture-proof effect, it can reduce the usage amounts of rosins (a) and the dispersant (b) in the moisture-proof coating agent. Therefore, an effect of reducing the carbon dioxide emissions when the coated paper is discarded can also be expected.

[0028] <Other additives> In the present invention, in addition to the above (a), (b), (c), and (d), various additives generally used in paints such as a viscosity modifier, an antifoaming agent, a preservative, a surface conditioner, a dye, a surface tension modifier, a lubricant, an anti-blocking agent, an antioxidant, and an ultraviolet absorber can be used for the moisture-proof coating agent as long as the effects are not impaired. In addition, waxes known for uses such as lubricants and anti-blocking agents can be used. As is conventionally known, using this has the merit of improving the moisture permeability at the same time, but since the recoatability and the adhesiveness are significantly reduced, it is necessary to minimize the usage amount. With respect to the total amount of rosins (a), the dispersant (b), and the platy layered silicate mineral (d), a mass ratio of 10% or less is preferable.

[0029] The waxes preferably have biodegradability by microorganisms. Specifically, plant-based waxes such as beeswax, candelilla wax, carnauba wax, rice bran wax, or shellac wax, animal-based waxes such as beeswax, shellac wax, or lanolin, mineral-based waxes such as montan wax or ozokerite, petroleum-based waxes such as paraffin wax or microcrystalline wax, Fischer-Tropsch wax, fatty acid ester-based waxes, or synthetic waxes such as fatty acid amides can be mentioned. One or a combination of plural of these can be used. Among these, plant-based waxes or animal-based waxes that are of biological origin and have carbon neutrality are preferable.

[0030] As a typical usage form of the water-based emulsion moisture-proof coating agent of the present invention, coating on paper or paperboard can be mentioned. <Paper, paperboard> The paper or paperboard used in this usage form can be used without particular limitation as long as it is a general paper or paperboard mainly composed of biodegradable pulp. Specifically, examples include high-quality paper, pure white roll paper, unbleached or bleached kraft paper, glassine paper, coated paper, liner base paper, paper tube base paper, white cardboard, chipboard, etc.

[0031] A coating layer for liquid absorption control, a coating layer for filling unevenness on the surface of the paper or paperboard to make it smooth, etc. may be provided between the paper or paperboard and the moisture-proof coating layer.

[0032] <Coating and drying methods> The coating method can be used without limitation as long as it is a known method. For example, bar coating, blade coating, die coating, curtain coating, air knife coating, spray coating, gravure coating, flexo coating, size press coating, etc. can be mentioned.

[0033] The drying method of the wet coating film can be used without limitation as long as it is a known method. For example, cylinder heating, steam heating, hot air heating, infrared heating, high-frequency heating, etc. can be mentioned.

Examples

[0034] Hereinafter, the present invention will be specifically described based on examples of the present invention, but the present invention is not limited to these examples.

[0035] <Preparation of rosins (a)> (Production example 1 of acid-modified rosin) 90 parts of gum rosin was put into a four-neck separable flask equipped with a heating device, a stirring device, a thermometer, and a nitrogen introduction tube, and heated and melted under a nitrogen atmosphere. Next, 10 parts of maleic anhydride (manufactured by Junsei Chemical Co., Ltd.) was added, and then heated and stirred until it reached 200 °C, and further reacted for 4 hours while maintaining the temperature to obtain maleic acid-modified rosin (M rosin).

[0036] (Production Example 2 of Acid-Modified Rosin) 88 parts of gum rosin were charged into a four-neck separable flask equipped with a heating device, a stirring device, a thermometer, and a nitrogen inlet tube, and heated and melted under a nitrogen atmosphere. Next, 12 parts of fumaric acid (manufactured by Junsei Chemical Co., Ltd.) were added, and the mixture was heated and stirred until it reached 200°C, and then reacted for 4 hours while maintaining the temperature to obtain fumaric acid-modified rosin (F rosin).

[0037] (Production Example of Esterified Rosin) 90 parts of gum rosin were charged into a four-neck separable flask equipped with a heating device, a stirring device, a thermometer, and a nitrogen inlet tube, and heated and melted under a nitrogen atmosphere. Next, 5 parts of fumaric acid were added, and the mixture was heated and stirred until it reached 200°C, and then reacted for 3 hours while maintaining the temperature. Then, it was cooled to 180°C, and 11 parts of ethanediol (manufactured by Kanto Chemical Co., Inc.) were further added, and the mixture was reacted at 240 - 260°C for 8 hours to obtain an esterified product of acid-modified rosin (E rosin).

[0038]

Table 1

[0039] (Preparation of Dispersant (b) Having Anionic Group) (Synthesis Example of Polymer Dispersant) Into a four-neck separable flask equipped with a heating device, a stirring device, a cooling tube, a thermometer, and a nitrogen inlet tube, 33.9 parts of styrene, 33.9 parts of butyl methacrylate, 135.6 parts of 50% acrylamide, 42.4 parts of 80% methacrylic acid, 4.6 parts of 4-methyl-2,4-diphenyl-1-pentene, 3.9 parts of dodecyl mercaptan, 0.4 part of sodium dodecylbenzenesulfonate, 10.9 parts of ammonium persulfate, and 635.6 parts of water were added under a nitrogen atmosphere, stirred and mixed, and heated at 90 °C for 3 hours. Then, it was cooled to 70 °C, and 78.3 parts of a 25% aqueous sodium hydroxide solution and 20.6 parts of water were gradually added dropwise so that it became 1.0 equivalent to the anion equivalent of methacrylic acid and the solid content concentration became 20%. After stirring for 30 minutes and then cooling to room temperature, a styrene-acrylic polymer dispersant (PS-1) with a solid content of 20% was obtained. The solid content was obtained by taking 1 g of the dispersion in an aluminum cup with a diameter of 5 cm and drying it at 150 °C for 20 minutes using a forced convection electric dryer.

[0040] (Example of Dissolution of Casein) Into a four-neck separable flask equipped with a heating device, a stirring device, a cooling tube, and a thermometer, 200 parts of casein (manufactured by Fujifilm Wako Pure Chemical Corporation), 71 parts of 28% aqueous ammonia, and 729 parts of water were charged, heated to 85 °C with stirring, and dissolved over 20 minutes while maintaining the temperature to obtain a 20% casein solution (casein solution).

[0041] (Example of Dissolution of Lecithin Hydroxide) Into a four-neck separable flask equipped with a heating device, a stirring device, a cooling tube, and a thermometer, 400 parts of 50% lecithin hydroxide (trade name: NIKKOL Resinol SH50, manufactured by Nikko Chemicals Co., Ltd.) and 600 parts of water were charged and dissolved at room temperature over 20 minutes to obtain a 20% lecithin hydroxide solution (lecithin solution).

[0042] (Emulsification of Rosins (a) with Dispersant (b)) (Emulsification Example 1) Into a four-neck separable flask equipped with a heating device, a stirring device, a cooling pipe, and a thermometer, 1000 parts of M rosin obtained in Production Example 1 of acid-modified rosin were charged, and the temperature was raised to 140 to 150 °C and melted. While stirring vigorously, 500 parts of a polymer dispersant (PS-1) were gradually added and mixed to form a water-in-oil emulsion. Then, 1250 parts of water at 85 to 90 °C were gradually added thereto to form a stable oil-in-water emulsion, and then it was cooled to bring the internal temperature to 30 °C or lower. The obtained emulsion contained 41% solids (Emulsion 1).

[0043] (Emulsification Example 2) Into a four-neck separable flask equipped with a heating device, a stirring device, a cooling pipe, and a thermometer, 1000 parts of M rosin obtained in Production Example 1 of acid-modified rosin were charged, and the temperature was raised to 140 to 150 °C and melted. While stirring vigorously, 500 parts of a casein solution were gradually added and mixed to form a water-in-oil emulsion. Then, 1250 parts of water at 85 to 90 °C were gradually added thereto to form a stable oil-in-water emulsion, and then it was cooled to bring the internal temperature to 30 °C or lower. The obtained emulsion contained 40% solids (Emulsion 2).

[0044] (Emulsification Example 3) Into a four-neck separable flask equipped with a heating device, a stirring device, a cooling pipe, and a thermometer, 1000 parts of M rosin obtained in Production Example 1 of acid-modified rosin were charged, and the temperature was raised to 140 to 150 °C and melted. While stirring vigorously, 83 parts of a 24% aqueous ammonium dodecyl sulfate solution (trade name: Latemul AD-25, manufactured by Kao Corporation) were gradually added, and then 400 parts of a casein solution were gradually added and mixed to form a water-in-oil emulsion. Then, 1267 parts of water at 85 to 90 °C were gradually added thereto to form a stable oil-in-water emulsion, and then it was cooled to bring the internal temperature to 30 °C or lower. The obtained emulsion contained 40% solids (Emulsion 3).

[0045] (Emulsification Examples 4 to 9) Except that the composition was changed as shown in Table 2, rosin emulsions of Emulsification Examples 4 to 9 were obtained in the same manner as in Emulsification Example 3 (Emulsions 4 to 9).

[0046] (Emulsification Example 10) 1000 parts of M rosin obtained in Production Example 1 of acid-modified rosin were charged into a four-neck separable flask equipped with a heating device, a stirring device, a cooling tube, and a thermometer, and the temperature was raised to 140 to 150 °C and melted. While stirring vigorously, 1500 parts of water at 85 to 90 °C were gradually added, but an emulsion was not formed (Emulsion 10).

[0047] [Table 2] AD-25 aqueous solution: 24% ammonium dodecyl sulfate aqueous solution (trade name: Latemul AD-25, manufactured by Kao Corporation) OT-70 aqueous solution: 70% sodium bis(2-ethylhexyl) sulfosuccinate aqueous solution (trade name: Sunmorin OT-70, manufactured by Sanyo Chemical Industries, Ltd.)

[0048] The film-forming aid (c) used for the preparation of the moisture-proof coating agent was the following.

[0049] [Table 3]

[0050] (Preparation of Dispersed Liquid of Plate-Like Layered Silicate Mineral (d)) (Preparation Example 1 of Dispersed Liquid of Plate-Like Layered Silicate Mineral) 400 parts of engineered kaolin (trade name: Valisure HX, manufactured by Imerys Co., Ltd., kaolin, average particle size of about 10 μm, aspect ratio of about 100.) and 600 parts of water were placed in a stainless steel container, and using an ultra-high speed emulsifying and dispersing test apparatus (trade name: Lab Revolution, manufactured by Primix Corporation), the mixture was stirred at 3000 rpm for 10 minutes to obtain a dispersed liquid (Mineral Dispersed Liquid 1). (Preparation Examples 2 to 4 of Dispersed Liquid of Plate-Like Layered Silicate Mineral) Except that the charge was changed as shown in Table 4, the same procedure as in Preparation Example 1 of the dispersed liquid of plate-like layered silicate mineral was followed to obtain Mineral Dispersed Liquids 2 to 4.

[0051] (Preparation Example 5 of Flat Layered Silicate Mineral Dispersion) In a stainless steel container, 400 parts of engineered kaolin (trade name: Valisure HX, manufactured by Imerys Co., Ltd., kaolin, average particle size of about 10 μm, aspect ratio of about 100), 595 parts of water, and 5 parts of T-50 (trade name: Aron T-50, manufactured by Toagosei Co., Ltd., 43% aqueous solution of sodium polyacrylate) were taken, and using an ultra-high-speed emulsifying and dispersing test apparatus (trade name: Lab Revolution, manufactured by Primix Corporation), the mixture was stirred at 3000 rpm for 10 minutes to obtain a dispersion (mineral dispersion 5).

[0052]

Table 4

[0053] UW90 (trade name: Ultra White 90, manufactured by BASF, kaolin, average particle size of about 1 μm, aspect ratio of about 10). KP-G (trade name: Kunipia G, manufactured by Kunimine Industries Co., Ltd., montmorillonite, average particle size of about 1 μm, aspect ratio of about 200). ME-100 (trade name: Somashif ME-100, manufactured by Katakura Koppu Agri Co., Ltd., synthetic mica, average particle size of about 5 μm, aspect ratio of about 50). T-50 (trade name: Aron T-50, manufactured by Toagosei Co., Ltd., 43% solution of sodium polyacrylate)

[0054] <Preparation of Aqueous Emulsion Moisture-Proof Coating Agent> (Moisture-Proof Coating Agent 1) Into a four-neck separable flask equipped with a stirring device, 98 parts of emulsion 1 were charged, and subsequently 2 parts of concentration-adjusted water were charged. Thereto, 14.8 parts of 1,2-propylene glycol were gradually added under stirring. Thereafter, the stirring state was maintained for 5 minutes until the liquid became uniform and then taken out to obtain moisture-proof coating agent 1.

[0055] (Moisture-Proof Coating Agents 2 to 24) Moisture-proof coating agents 2 to 24 were obtained in the same manner as in the case of moisture-proof coating agent 1, except that the type of member and the addition amount were changed as shown in Table 5.

[0056] (Moisture-proof coating agent 25) Into a four-neck separable flask equipped with a stirring device, 98 parts of emulsion 1, subsequently 2 parts of concentration-adjusted water, and 10 parts of lecithin solution were added. While stirring, 4 parts of 1,2-diacetoxypropane were gradually added. Thereafter, the stirring state was maintained for 5 minutes until the liquid became uniform, and then it was taken out to obtain moisture-proof coating agent 25.

[0057] (Moisture-proof coating agent 26) Moisture-proof coating agent 26 was obtained in the same manner as moisture-proof coating agent 25, except that the lecithin solution was changed to a casein solution.

[0058] (Moisture-proof coating agent 27) Into a four-neck separable flask equipped with a stirring device, 50 parts of emulsion 2 were added. Subsequently, while stirring, 1.9 parts of 1,2-diacetoxypropane were gradually added. Thereafter, the stirring state was maintained for 5 minutes until the liquid became uniform, and then it was taken out to obtain moisture-proof coating agent 27.

[0059] (Moisture-proof coating agents 28 - 34) Moisture-proof coating agents 28 - 34 were obtained in the same manner as moisture-proof coating agent 27, except that the charge was changed as described in Table 6.

[0060] (Moisture-proof coating agent 35) Into a four-neck separable flask equipped with a stirring device, 49 parts of emulsion 1, subsequently 1 part of concentration-adjusted water, and 50 parts of mineral dispersion 1 were added. While stirring, 2 parts of 1,2-diacetoxypropane were gradually added. Thereafter, the stirring state was maintained for 5 minutes until the liquid became uniform, and then it was taken out to obtain moisture-proof coating agent 35.

[0061] (Moisture-proof coating agents 36 - 41) Moisture-proof coating agents 36 - 41 were obtained in the same manner as moisture-proof coating agent 35, except that the charge was changed as described in Table 6.

[0062] (Comparative moisture-proof coating agents 1 - 6) Comparative moisture-proof coating agents 1 - 6 were obtained in the same manner as moisture-proof coating agent 35, except that the charge was changed as described in Tables 5 and 6.

[0063] <Preparation of Moisture-proof Coating Agent> Into a four-neck separable flask equipped with a heating device, a stirring device, a cooling tube, a thermometer, and a nitrogen inlet tube, 1000 parts of propylene glycol monomethyl ether acetate were added under a nitrogen atmosphere. While refluxing the solvent, a mixture of 550 parts of styrene, 240 parts of 2-ethylhexyl acrylate, 210 parts of acrylic acid, and 0.1 part of ditertiary butyl peroxide was added dropwise and polymerized for 7 hours. Then, the solvent was removed to obtain an anionic styrene-acrylic copolymer (A). Into a reaction vessel equipped with a thermometer, a stirrer, a cooling tube, and a nitrogen gas inlet tube, 300 parts of an anionic styrene-acrylic copolymer (A), 43 parts of 28% aqueous ammonia, 16 parts of dimethylethanolamine, and 1164 parts of water were added to prepare an aqueous solution. Then, 400 parts of styrene and 300 parts of 2-ethylhexyl acrylate were added and stirred and mixed. Under a nitrogen stream at 40 °C, 1.8 parts of ammonium persulfate and 1.8 parts of sodium bisulfite were added to initiate polymerization, and emulsion polymerization was carried out at 75 to 85 °C for 3 hours to obtain an acrylic emulsion for moisture-proof processing (Reference Moisture-proof Coating Agent 1) with a solid content of 40%.

[0064]

Table 5

[0065]

Table 6

[0066] <Coating of Moisture-proof Coating Agent> The coating conditions of the moisture-proof coating agent and the measurement or evaluation methods for each evaluation item followed the following methods. (Coated Base Paper) One-sided glazed kraft paper: Basis weight 50 g / m 2 (Coating) The adhesion amount of each moisture-proof coating agent was 13 g / m in terms of solid content 2Using a bar coater, the base paper was coated on the matte surface so as to become [the required state], and dried at 110 °C for 0.5 minutes using a hot air dryer. Thereafter, conditioning was performed at 23 °C and 50% RH for 24 hours. (Water vapor permeability) Measurement was carried out in accordance with JIS Z0208 Moisture-proof Packaging Materials - Test Method for Water Vapor Permeability (Cup Method). Temperature and humidity conditions: Method B (40 °C / 90% RH · 24 hours) Orientation of test piece: Coat side facing outwards

[0067] (Example 1) For single-sided glossy kraft paper, moisture-proof coating agent 1 was coated and dried under the above conditions to obtain moisture-proof coating agent-coated paper. After conditioning, it was cut into a circle with a diameter of 70 mm, and the water vapor permeability was calculated by the above-described water vapor permeation cup method. The results are shown in Table 7.

[0068] (Examples 2 to 41) Moisture-proof coating agent-coated paper was obtained in the same manner as in Example 1 except that the moisture-proof coating agent was changed as shown in Table 7. Further, in the same manner as in Example 1, the water vapor permeability was evaluated. These results are shown in Tables 7 and 8.

[0069] (Comparative Example 1) Since the moisture-proof coating agent could not be prepared, coating evaluation was not performed.

[0070] (Comparative Examples 2 to 7) Moisture-proof coating agent-coated paper was obtained in the same manner as in Example 1 except that the moisture-proof coating agent was changed as shown in Table 4. Further, in the same manner as in Example 1, the water vapor permeability was evaluated. These results are shown in Tables 7 and 8.

[0071]

Table 7

[0072]

Table 8

[0073] When comparing Examples 1 to 41 that satisfy the conditions of the present invention with Comparative Examples 2 to 7 that do not satisfy the conditions of the present invention, it can be seen that when the aqueous emulsion moisture-proof coating agent obtained in Examples 1 to 41 is applied, the moisture permeability of the paper is excellent. In addition, in Reference Example 1, compared with Example 1, the component corresponding to rosin (a) is a styrene-acrylic polymer composed of fossil fuel-derived components, so it does not contain bio-derived components and has no carbon neutrality.

[0074] (Examples 2 to 24) Compared with Example 1, the film-forming aid (c) is triethyl citrate and / or an organic compound having a solubility parameter value of 7 or more and 11 or less, and is contained in the range of (c) / (a) = 2 / 98 to 40 / 60 by mass ratio with respect to rosin (a), so it is excellent in moisture permeability.

[0075] (Example 25) Compared with Example 4, since the dispersant (b) contains lecithin, it is excellent in moisture permeability.

[0076] (Examples 26 to 34) Compared with Example 4, since the dispersant (b) contains casein, it is excellent in moisture permeability.

[0077] (Examples 35 to 41) Compared with Example 4, since it contains a flat-layered silicate mineral (d), the moisture permeability is maintained even when the rosin (a) contained in the moisture-proof coating layer is reduced, and it is excellent in reducing the carbon dioxide emission amount when the moisture-proof coated paper is discarded.

Claims

1. In the water-based emulsion moisture-proof coating agent, Rosins (a) Dispersant having an anionic group (b) (c) at least one film-forming aid selected from triethyl citrate, ethyl 3-ethoxypropionate, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol butyl methyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monopropyl ether, 1,2-diacetoxypropane, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether acetate, 3-methoxy-1-butanol, 3-methoxybutyl acetate, 1,3-diacetoxybutane, 1,4-diacetoxybutane, and glyceryl triacetate; and water and wherein the mass ratio of the rosin (a) satisfies the following formula: (a) / (total amount of organic compounds in moisture-proof coating agent)×100≧70(%)

2. 2. The aqueous emulsion moisture-proof coating agent according to claim 1, wherein the film-forming auxiliary (c) is triethyl citrate and / or an organic compound having a solubility parameter value of 7 or more and 11 or less, and is contained relative to the rosin (a) in a mass ratio of (c) / (a) in the range of 2 / 98 to 40 / 60.

3. 2. The water-based emulsion moisture-proof coating agent according to claim 1, wherein at least one of the dispersants (b) is casein.

4. The aqueous emulsion moisture-proof coating agent according to claim 1, further comprising a flat layered silicate mineral (d) in a mass ratio of (d) / ((a)+(b))=20 / 80 to 75 / 25 relative to the total of the rosins (a) and the dispersant (b).

5. A method for producing paper or paperboard, comprising coating the paper or paperboard with the aqueous emulsion moisture-proof coating agent according to any one of claims 1 to 4.

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