Biodegradable resin water dispersion and method for producing the same

Abstract

To provide a biodegradable resin water dispersion utilizing a biomass base material having biodegradability available as a coating agent for paper.SOLUTION: A biodegradable resin water dispersion usable as an aqueous coating agent for paper with low environmental loads can be obtained while satisfying performances such as water resistance and heat sealability required for a conventional coating agent for aqueous paper, using a biodegradable resin water dispersion composed of a polyester-based biodegradable resin (a), rosins (b) and caseins (c). The polyester-based biodegradable resin (a) is preferably one or two or more kinds selected from the group consisting of polycaprolactone, polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate terephthalate.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a biodegradable resin aqueous dispersion and a method for producing coated paper having the biodegradable resin aqueous dispersion as a coating layer. [Background technology]

[0002] In recent years, environmental issues have led to a trend away from petroleum and plastics, and interest in paper, a renewable resource, has been growing. As various plastic products are being replaced by paper products, petroleum-based water dispersions (Patent Document 1) that can impart properties such as heat sealability by being coated on paper, are being widely used.

[0003] However, recently, the problem of plastic waste, including microplastics, has come into greater focus, and there is a growing demand for the coating agents applied to paper to be biodegradable. As a replacement for petroleum-based aqueous dispersions, a biodegradable resin aqueous dispersion (Patent Document 2) has been proposed.

[0004] Furthermore, in addition to biodegradability, there is an increasing need for the utilization of biomass materials, and an aqueous dispersion that combines a biodegradable resin and a biomass material (Patent Document 3) has been proposed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-179909 A [Patent Document 2] Patent Publication No. 2022-060830 [Patent Document 3] JP 2023-036546 A

[0006] On the other hand, petroleum-based dispersants or emulsifiers are still used for dispersing resins in water, and although there has been a challenge to switch to dispersants and emulsifiers made from biomass materials and with biodegradability, based on current knowledge it has been difficult to obtain an aqueous dispersion. Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above circumstances, an object of the present invention is to provide a biodegradable resin aqueous dispersion that utilizes a biomass material having biodegradability. [Means for solving the problem]

[0008] As a result of intensive research into solving the above-mentioned problems, the inventors discovered that the problems could be solved without impairing the desired performance by using a combination of a polyester biodegradable resin and biomass materials such as rosins and caseins, and thus completed the present invention. That is, the present invention provides <1> A biodegradable resin aqueous dispersion comprising a polyester-based biodegradable resin (a), a rosin (b) and a casein (c); <2> The polyester-based biodegradable resin (a) is one or more selected from the group consisting of polycaprolactone, polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate terephthalate. <1> The biodegradable resin aqueous dispersion according to claim 1, <3> The composition is characterized in that the mass ratio of the polyester biodegradable resin (a) is (a) / {(a)+(b)+(c)}=10-85%, the mass ratio of the rosins (b) is (b) / {(a)+(b)+(c)}=10-85%, and the mass ratio of the caseins (c) is (c) / {(a)+(b)+(c)}=3-10%. <1> or <2> The biodegradable resin aqueous dispersion according to claim 1, <4> The above <1> ~ <3> A method for producing coated paper, comprising coating paper or paperboard with the biodegradable resin aqueous dispersion according to any one of claims 1 to 4. It is. Effect of the Invention

[0009] According to the present invention, by using a polyester-based biodegradable resin and rosins and caseins, which are biomass materials and have biodegradability, in an aqueous resin dispersion, it is possible to obtain an aqueous biodegradable resin dispersion that can be used as an aqueous paper coating agent that has a low environmental impact while satisfying the water resistance and heat sealability performance required of conventional aqueous paper coating agents. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail. 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 on a mass basis. In addition, a numerical range expressed using "~" includes the numerical values ​​written before and after it.

[0011] The biodegradable resin water dispersion of the present invention is prepared by dispersing a polyester-based biodegradable resin (a) together with a rosin (b) and a casein (c) in water.

[0012] <Polyester-based biodegradable resin (a)> The polyester-based biodegradable resin (a) includes polycaprolactones, such as polycaprolactones, copolymers of caprolactone and hydroxycarboxylic acid, excluding polylactic acids, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polybutylene terephthalate succinate, polyhydroxyalkanoic acids, polyhydroxybutyrate, polyhydroxyvalerate, polyhydroxyhexanoate, polyglycolic acid, etc., and one or more of these can be used in combination. Among them, from the viewpoint of emulsification and heat sealability, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, and polycaprolactone are preferred, and polycaprolactone is more preferred.

[0013] <Rosins (b)> Rosins (b) refer to raw rosins obtained from plants and / or those that have been partially or completely chemically modified by acid modification, esterification, etc. Furthermore, they also include those that have had part or all of the acid groups neutralized with an alkaline compound. Specific examples of rosins (b) include raw rosins such as gum rosin, wood rosin, and tall oil rosin, hydrogenated rosins obtained by adding hydrogen to raw rosins, acid-modified rosins obtained by adding α,β-unsaturated dicarboxylic acids such as maleic acid and fumaric acid to these rosins, and esterified rosins obtained by esterifying these rosins with hydroxyl-containing compounds such as ethanediol and pentaerythritol. The origin of the raw rosin is not particularly limited, and examples thereof include Chinese gum rosin (hereinafter sometimes abbreviated as CGR), Vietnamese gum rosin (hereinafter sometimes abbreviated as VGR), Indonesian gum rosin (hereinafter sometimes abbreviated as IGR), and Brazilian gum rosin (hereinafter sometimes abbreviated as BGR). Among these, gum rosin and its acid-modified rosin are preferred. One or more of these can be used in combination. Specific examples of alkaline compounds 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. Ammonia is easily volatilized from the acid group when the coating film is dried, and the hydrophobicity of the rosins is increased, resulting in excellent water resistance of the coating film after drying.

[0014] <Caseins (c)> Examples of caseins (c) include acid casein, rennet casein, and caseinate. Acid casein refers to caseins obtained by precipitating milk with acid. Rennet casein refers to caseins obtained by coagulating milk with rennet. Caseinate refers to caseins obtained by neutralizing acid casein obtained by precipitating milk with acid with an alkali. Acid casein is preferred from the viewpoint of availability.

[0015] In the biodegradable resin aqueous dispersion of the present invention, from the viewpoints of emulsifiability, water resistance and heat sealability of coated paper, the mass ratio (%) of each component of polyester-based biodegradable resin (a), rosins (b) and caseins (c) contained in the biodegradable resin aqueous dispersion is preferably (a):(b):(c)=10-85:10-85:3-10, where the total of components (a)-(c) is taken as 100. In particular, when the water resistance of coated paper is important, it is preferable to adjust (a):(b):(c)=10-75:20-85:3-10, and when the heat sealability of coated paper is important, it is preferable to adjust (a):(b):(c)=20-85:10-75:3-10. In consideration of the balance of performance, it is more preferable that (a):(b):(c)=20-75:20-75:3-10.

[0016] <Additives> In the present invention, in addition to the above components (a) to (c), various additives generally used in paints, such as emulsifiers, viscosity modifiers, antifoaming agents, preservatives, surface modifiers, dyes, surface tension modifiers, lubricants, antiblocking agents, antioxidants, UV absorbers, dispersion stabilizers, etc., may be added to the biodegradable resin aqueous dispersion in the range that does not impair its physical properties and effects. From the viewpoints of utilization of biomass materials and biodegradability, the amount of each additive used is preferably 10% or less based on the total amount of the polyester biodegradable resin (a), rosins (b), and caseins (c).

[0017] <Method for producing biodegradable resin aqueous dispersion> The method for producing the biodegradable resin water dispersion of the present invention is not limited, but an example of the method is an inversion emulsification method, in which the mixture of the above (a), (b), and (c) is heated to 100° C. or more and 200° C. or less, kneaded, and then hot water is gradually added to cause phase inversion emulsification to form a dispersion.

[0018] The biodegradable resin water dispersion is a homogeneous dispersion of polyester-based biodegradable resin (a) in water together with rosins (b) and caseins (c) in the form of particles, and the average particle size of the particles is preferably in the range of 0.1 to 100 μm, more preferably in the range of 0.5 to 50 μm, and even more preferably in the range of 0.5 to 20 μm. The average particle size of the particles can be measured using a laser diffraction / scattering type particle size distribution analyzer LA-910 (manufactured by Horiba, Ltd.).

[0019] <Heat sealant> The biodegradable resin water dispersion of the present invention can be used as a component of a heat sealant. When producing a heat sealant containing the biodegradable resin water dispersion obtained by the present invention, general-purpose organic solvents such as isopropyl alcohol and butyl cellosolve, fillers, waxes, film-forming assistants, leveling agents, defoamers, and preservatives can be added as necessary. The coating substrate when using the heat sealant containing the biodegradable resin water dispersion obtained by the present invention is paper or paperboard. The use of the heat sealant is not particularly limited, but it is suitable for any use that requires heat sealability, and is particularly suitable as a replacement for polyethylene laminate in uses where heat sealability has been obtained by polyethylene laminate in the past.

[0020] <Paper, paperboard> The paper or paperboard used in this application can be any ordinary paper or paperboard that is mainly composed of biodegradable pulp, without any particular restrictions.Specific examples include fine 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.

[0021] <Coating and drying method> The coating method can be any known method without limitation, for example, bar coating, blade coating, die coating, curtain coating, air knife coating, spray coating, gravure coating, flexo coating, size press coating, etc., and the coating amount of the biodegradable resin aqueous dispersion is 0.1 to 15 g / m2 in terms of the solid content of the coating layer. 2 It is preferable to set the thickness to 1 to 10 g / m2 It is more preferable that:

[0022] The method for drying the wet coating film can be any known method without limitation, such as cylinder heating, steam heating, hot air heating, infrared heating, and high-frequency heating.

[0023] The coated paper coated with the biodegradable resin aqueous dispersion of the present invention can be suitably used as a packaging material for foods, medical products, electronic parts, etc., either as is or by laminating it with various resins or pasting it with various films or aluminum foil. EXAMPLES

[0024] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following, % and parts respectively indicate mass % and mass parts unless otherwise specified.

[0025] <Preparation of rosins (b)> (Production example of acid-modified rosin) 90 parts of gum rosin (blended with a mass ratio of IGR:CGR:VGR = 8:1:1) was placed in a four-necked separable flask equipped with a heater, stirrer, thermometer, and nitrogen inlet tube under a nitrogen atmosphere and melted by heating. Next, 10 parts of maleic anhydride (manufactured by Junsei Chemical Co., Ltd.) was 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 maleic acid-modified rosin.

[0026] <Preparation of biodegradable resin aqueous dispersion consisting of polyester-based biodegradable resin (a), rosins (b), and caseins (c)> Example 1 In a four-necked separable flask equipped with a heating device, a stirring device, a cooling tube, and a thermometer, 85 parts of polycaprolactone (product name "Capa6800", manufactured by INGEVITY), 10 parts of M rosin obtained in the manufacturing example of acid-modified rosin, and 5 parts of acid casein (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) were added, heated to 150 ° C., and kneaded. While stirring, 30 parts of 90 ° C. water containing 1 part of 28% ammonia water for neutralization was gradually added and mixed, and phase inversion emulsification was performed to obtain a water-in-oil emulsion. Further, 120 parts of 90 ° C. water was gradually added to this to obtain a stable oil-in-water emulsion, and then cooled to an internal temperature of 30 ° C. or less to obtain a biodegradable resin water dispersion with a concentration of 40%.

[0027] (Examples 2 to 15) The types and amounts of polyester-based biodegradable resin (a), rosins (b), and caseins (c) added were changed as shown in Table 1. Examples 6 and 7 were similar to Example 1 except that the additives shown in Table 1 were added as emulsifiers. Example 10 was similar to Example 1 except that phase inversion emulsification was performed under pressure, and a 40% concentration aqueous dispersion of biodegradable resin was obtained.

[0028] (Comparative Examples 1 to 13) The types and amounts of polyester-based biodegradable resins (a), rosins (b), and caseins (c) added were changed as shown in Table 1. In Comparative Examples 7, 8, and 11, phase inversion emulsification was carried out under pressure. All other steps were the same as in Example 1, but no dispersion was obtained.

[0029] [Table 1]

[0030] Abbreviations in the table PCL: Polycaprolactone (product name: Capa6800, manufactured by INGEVITY) PBS: Polybutylene succinate (product name: FORZEASDM9B01, manufactured by Mitsubishi Chemical Corporation) PBAT: Polybutylene adipate terephthalate (product name: TH801T, manufactured by XINJIANG BLUE RIDGE TUNHE POLYESTER CO., LTD.) M rosin: Maleic acid modified rosin Unmodified rosin: Gum rosin (IGR) Acid casein: Acid casein (product name: Casein - derived from milk, Fujifilm Wako Pure Chemical Industries, Ltd.) OT-70: Sodium bis(2-ethylhexyl) sulfosuccinate (product name: Sanmorin OT-70, manufactured by Sanyo Chemical Industries, Ltd.) AD-25: Ammonium dodecyl sulfate aqueous solution (product name: Latemul AD-25, manufactured by Kao Corporation)

[0031] <Properties and Performance of Examples 1 to 15 and Comparative Examples 1 to 13> The properties and performance of the biodegradable resin aqueous dispersion obtained using the component ratios shown in Table 1 were measured and evaluated as follows. [Dispersion state] The average particle size of the particles was measured using a laser diffraction / scattering type particle size distribution analyzer LA-910 (manufactured by Horiba, Ltd.). Average particle sizes of 0.1 to 50 μm were rated A, those between 50 μm and 100 μm were rated B, and those over 100 μm or unable to be measured were rated C. Anything above B was deemed industrially usable. [Heat sealability] The obtained biodegradable resin aqueous dispersion was mixed with water at a basis weight of 50 g / m 2 On one-sided glazed bleached kraft paper, the adhesion amount is 8g / m2 in solids. 2 The non-glossy side was coated using a bar coater No. 12 so that the coating would become uniform, and then dried using a hot air dryer at 110°C for 0.5 minutes. For Example 10, the coating was dried at 150°C for 1 minute. After that, the moisture was conditioned at 23°C and 50% RH for 24 hours, and then each coated paper was cut to 75 mm x 110 mm and folded in half lengthwise with the coated side inward. The folded side was sealed with a seal width of 20 mm from the edge, and the seal was tested at 120°C, 1 second, and 2 kgf / cm using a heat seal tester TP-701-B (manufactured by Tester Sangyo). 2The specimen was then heat-pressed at 150°. This was then divided into 5 equal parts to create 5 test pieces measuring 15mm x 55mm. Each test piece was opened 180° with the sealed area in the center, and pulled vertically at a gripping distance of 30mm and a peeling speed of 300mm / min using a Tensilon universal testing machine RTG1210 (manufactured by A&D), to measure the maximum load. The average value of the 5 test pieces was taken as the heat seal strength. A score of A was given for 4.0N / 15mm or more, B for 2.0-4.0N / 15mm, and C for less than 2.0N / 15mm. A score of B or more was deemed industrially usable. [Water resistance test] The obtained biodegradable resin aqueous dispersion was mixed with water at a basis weight of 50 g / m 2 On one-sided glazed bleached kraft paper, the adhesion amount is 8g / m2 in solids. 2 The non-glossy side was coated using a bar coater No. 12 so that the coating would be 0.5 minutes at 110°C using a hot air dryer. For Example 10, the coating was dried at 150°C for 1 minute. After that, the humidity was conditioned at 23°C and 50% RH for 24 hours, and the Cobb water absorbency was measured as follows. The resulting coated paper was cut into 10 cm squares and the mass was measured. The liquid-contacting surface of the coated paper was contacted with ion-exchanged water at 20°C for 2 minutes in accordance with JIS P 8140:1998, and the mass was measured. From the difference in mass before and after contact with ion-exchanged water, the Cobb water absorbency was measured in accordance with JIS P 8140:1998. 0 g / m 2 ~3g / m 2 A, 3g / m 2 Super~10g / m 2 B, 10g / m 2 Anything above that grade was rated C, and anything above B was deemed suitable for industrial use.

[0032] The results are shown in Table 2.

[0033] [Table 2]

[0034] From Table 2, it was shown that Examples 1 to 15, which used all of the polyester-based biodegradable resin (a), rosins (b), and caseins (c) specified in the present invention, had excellent emulsifiability compared to Comparative Examples 1 to 13, which did not use any of these components, and that it was possible to obtain an aqueous dispersion using a resin and dispersant that are biomass materials and have biodegradability. Furthermore, from Table 2, a comparison between Examples 1 to 14 and Example 15 showed that by setting the content mass ratio of the polyester-based biodegradable resin (a) and the rosins (b) within a preferred range, a biodegradable resin aqueous dispersion with better heat sealability was obtained, and a comparison between Examples 2 to 15 and Example 1 showed that by setting the content mass ratio of the polyester-based biodegradable resin (a) and the rosins (b) within a preferred range, a biodegradable resin aqueous dispersion with better water resistance of the coating film was obtained. Furthermore, it was shown that by setting the mass ratio of the polyester-based biodegradable resin (a) and the rosins (b) within a range that is included in both of the above-mentioned preferred ranges, a biodegradable resin aqueous dispersion having a well-balanced and excellent performance can be obtained.

Claims

1. A biodegradable resin aqueous dispersion comprising (a) a polyester-based biodegradable resin, (b) a rosin, and (c) a casein.

2. 2. The biodegradable resin water dispersion according to claim 1, wherein the polyester-based biodegradable resin (a) is one or more selected from the group consisting of polycaprolactone, polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate terephthalate.

3. 2. The biodegradable resin water dispersion according to claim 1, wherein the mass ratio of the polyester-based biodegradable resin (a) is (a) / {(a)+(b)+(c)}=10-85%, the mass ratio of the rosins (b) is (b) / {(a)+(b)+(c)}=10-85%, and the mass ratio of the caseins (c) is (c) / {(a)+(b)+(c)}=3-10%.

4. A method for producing coated paper, comprising coating paper or paperboard with the biodegradable resin aqueous dispersion according to any one of claims 1 to 3.

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