A method for improving the dispersibility of crystalline resins having hydrophilic groups in neutral water.

Abstract

The present invention provides a method for improving the dispersibility of a crystalline resin having a hydrophilic group into neutral water, the method comprising an amorphization step in which a crystalline resin having a hydrophilic group is amorphized. The present invention is able to provide a method which improves the dispersibility of a water-soluble resin having excellent moisture resistance into neutral water.

Description

Technical Field

[0001] The present invention relates to a method for improving the dispersibility of a crystalline resin having a hydrophilic group in neutral water.

Background Art

[0002] In some applications of resins, rapid removal may be required after the resin has served its purpose. As a means for removing the resin, dissolution with a solvent or an aqueous alkali solution may be considered (for example, Japanese Patent Application Laid-Open No. 2001-131484).

Summary of the Invention

[0003] The present invention is a method for improving the dispersibility of a crystalline resin having a hydrophilic group in neutral water, which includes an amorphization step of amorphizing the crystalline resin having a hydrophilic group. Detailed Description of the Invention

[0004] Removing the resin using an aqueous alkali solution is not preferable from the viewpoints of the working environment and safety. As a solution to this, using a water-soluble resin that dissolves in neutral water such as polyvinyl alcohol can be considered. However, since conventional water-soluble resins are inferior in moisture resistance, they may be damaged by moisture in the environment when used in a relatively high-humidity environment, and may not be able to serve their purpose.

[0005] In response to the above problems, it may be considered to use a water-soluble resin that is excellent in moisture resistance and is not easily damaged even when used in a high-humidity environment. However, in order to remove such a water-soluble resin with neutral water, it is often necessary to raise the temperature of the neutral water, which poses problems from the viewpoints of safety and energy saving.

[0006] The present invention provides a method for improving the dispersibility of a water-soluble resin excellent in moisture resistance in neutral water.

[0007] The present invention is a method for improving the dispersibility of a crystalline resin having a hydrophilic group in neutral water, which includes an amorphization step of amorphizing the crystalline resin having a hydrophilic group.

[0008] According to the present invention, it is possible to provide a method for improving the dispersibility of a water-soluble resin with excellent moisture resistance in neutral water.

[0009] The following describes one embodiment of the present invention.

[0010] <Method for improving the dispersibility of hydrophilic crystalline resins in neutral water> The method for improving the dispersibility of a hydrophilic crystalline resin in neutral water according to this embodiment (hereinafter also simply referred to as the water dispersibility improvement method) includes an amorphous step of amorphousizing the hydrophilic crystalline resin. In this specification, dispersion of a hydrophilic crystalline resin in neutral water means dispersion of the hydrophilic crystalline resin in neutral water by dissolution of the hydrophilic crystalline resin in neutral water, or by the collapse of a molded body of the hydrophilic crystalline resin in neutral water. Furthermore, dispersibility of a hydrophilic crystalline resin in neutral water means the ease of dissolution of the hydrophilic crystalline resin in neutral water, or the ease of dispersion of the hydrophilic crystalline resin in neutral water by the collapse of a molded body of the hydrophilic crystalline resin in neutral water. According to the water dispersibility improvement method of this embodiment, it is possible to improve the dispersibility of a water-soluble resin with excellent moisture resistance in neutral water. The reason why this water dispersibility improvement method produces such an effect is not clear, but it is thought to be as follows.

[0011] It is believed that crystalline resins containing hydrophilic groups exhibit high moisture resistance immediately after melt synthesis due to the aggregation and crystallization of the hydrophilic groups. However, when crystalline resins containing hydrophilic groups are heated above their melting point after molding, the crystals melt, molecular mobility increases, and the hydrophilic groups re-aggregate, resulting in the loss of crystals due to the hydrophobic portions. This is thought to improve dispersibility in neutral water.

[0012] [Amorphization process] The amorphous process is a process of amorphousizing the crystalline resin.

[0013] The crystalline resin having hydrophilic groups is not particularly limited as long as it is crystalline and dispersible in neutral water. Examples of the crystalline resin having hydrophilic groups include a crystalline water-soluble resin having monomer units A having hydrophilic groups other than the hydrophilic groups constituting the polymerization involved in the formation of the crystalline resin having hydrophilic groups (hereinafter also simply referred to as hydrophilic groups), and monomer units B that do not have the hydrophilic groups.

[0014] The neutral water mentioned above may be water or an aqueous solution with a pH of 6 to 8, preferably 6.5 to 7.5, at 25°C. Specifically, the neutral water may be deionized water, pure water, tap water, or industrial water, with deionized water or tap water being preferred from the viewpoint of availability. The neutral water may also contain other components such as water-soluble organic solvents and surfactants. Examples of water-soluble organic solvents include lower alcohols such as methanol, ethanol, and 2-propanol; glycol ethers such as propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monotertiary butyl ether, and diethylene glycol monobutyl ether; and ketones such as acetone and methyl ethyl ketone. Examples of surfactants include anionic surfactants such as alkyl sulfate esters, alkyl ether sulfate esters, olefin sulfonates, and alkyl ether carboxylates; cationic surfactants such as alkyltrimethylammonium salts; and nonionic surfactants such as polyoxyethylene alkyl ethers and alkyl glycosides.

[0015] Examples of crystalline resins having hydrophilic groups include water-soluble polyester resins, water-soluble polyamide resins, water-soluble polyimide resins, water-soluble acrylic resins, water-soluble polyurethane resins, water-soluble polyallylamine resins, water-soluble phenolic resins, water-soluble epoxy resins, water-soluble phenoxy resins, water-soluble urea resins, water-soluble melamine resins, and polyvinyl alcohol resins, as well as modified products of these resins. These can be used individually or in combination of two or more. Among these, from the viewpoint of achieving the effects of the present invention, one or more selected from the group consisting of water-soluble polyester resins, water-soluble polyamide resins, and water-soluble acrylic resins are preferred, and water-soluble polyester resins are more preferred.

[0016] [Monomer Unit A] The monomer unit A has a hydrophilic group. The monomer used to derive the monomer unit A is also referred to as monomer A.

[0017] The hydrophilic group can be one or more selected from the group consisting of cationic groups, neutral groups, and anionic groups, as it imparts dispersibility in neutral water. Among these, one or more selected from the group consisting of anionic groups are preferred from the viewpoint of imparting dispersibility in neutral water, and sulfonic acid bases are more preferred.

[0018] The aforementioned sulfonic acid base is -SO3M, from the viewpoint of imparting dispersibility in neutral water and facilitating polymerization reactions during the production of hydrophilic crystalline resins. 3 (However, M 3) represents the counterion of the sulfonic acid group constituting the sulfonic acid base, and from the viewpoint of imparting dispersibility in neutral water, one or more selected from the group consisting of metal ions and ammonium ions is preferred, one or more selected from the group consisting of metal ions is more preferred, one or more selected from the group consisting of alkali metal ions and alkaline earth metal ions is even more preferred, one or more selected from the group consisting of alkali metal ions is even more preferred, one or two selected from the group consisting of sodium ions and potassium ions is even more preferred, and sodium ions are even more preferred.

[0019] The monomer unit A is not particularly limited as long as it is a monomer unit having a hydrophilic group, but from the viewpoint of providing dispersibility in neutral water and improving moisture resistance, a dicarboxylic acid monomer unit having a hydrophilic group is preferred.

[0020] From the viewpoint of providing dispersibility in neutral water, improving moisture resistance, and facilitating polymerization reactions during the production of hydrophilic crystalline resins, monomer A is preferably one or more selected from the group consisting of hydrophilic carboxylic acids, amines, amino acids, and their salts, and more preferably a hydrophilic carboxylic acid or its salt. Among the carboxylic acids or their salts, from the same viewpoint, aromatic carboxylic acids or their salts having hydrophilic groups are preferred, and one or more selected from the group consisting of sulfonic acid base-containing aromatic dicarboxylic acids and their salts are more preferred. Among these, from the same viewpoint, one or more selected from the group consisting of sulfophthalic acid and sulfonaphthalenedicarboxylic acid and their salts are preferred, one or more selected from the group consisting of sulfophthalic acid and its salts are even more preferred, one or more selected from the group consisting of sulfoisophthalic acid and sulfoterephthalic acid and their salts are even more preferred, and 5-sulfoisophthalic acid or its salt is even more preferred.

[0021] The content of the hydrophilic groups in the crystalline resin having the hydrophilic groups is preferably 0.4 mmol / g or more, more preferably 0.6 mmol / g or more, and even more preferably 0.7 mmol / g or more, from the viewpoint of providing dispersibility in neutral water, and from the viewpoint of improving moisture resistance, it is preferably 3.0 mmol / g or less, more preferably 2.0 mmol / g or less, even more preferably 1.5 mmol / g or less, and even more preferably 1.0 mmol / g or less.

[0022] The ratio of the amount of substance of monomer unit A to the total amount of substance of all monomer units of the hydrophilic group-containing crystalline resin is preferably 5 mol% or more, more preferably 7 mol% or more, and even more preferably 10 mol% or more, from the viewpoint of imparting dispersibility in neutral water, and preferably 35 mol% or less, more preferably 30 mol% or less, even more preferably 20 mol% or less, and even more preferably 15 mol% or less, from the viewpoint of improving moisture resistance.

[0023] [Monomer Unit B] The monomer unit B does not have a hydrophilic group. The monomer used to derive the monomer unit B is also referred to as monomer B. From the viewpoint of improving moisture resistance, the monomer unit B is preferably a dicarboxylic acid monomer unit that does not have a hydrophilic group (hereinafter also referred to as dicarboxylic acid monomer unit B).

[0024] The dicarboxylic acid used to derive the dicarboxylic acid monomer unit B is more preferably one or more selected from the group consisting of aromatic dicarboxylic acids without hydrophilic groups and aliphatic dicarboxylic acids without hydrophilic groups, from the viewpoint of improving moisture resistance and facilitating polymerization reactions during the production of hydrophilic resins, and even more preferably one or more selected from the group consisting of aromatic dicarboxylic acids without hydrophilic groups.

[0025] Examples of the aromatic dicarboxylic acid having no hydrophilic group include one or more selected from the group consisting of benzenedicarboxylic acid, furandicarboxylic acid, and naphthalenedicarboxylic acid. Among these, from the viewpoint of improving moisture resistance, one or more selected from the group consisting of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are preferable.

[0026] Examples of the aliphatic dicarboxylic acid having no hydrophilic group include one or more selected from the group consisting of malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, and 1,3-adamantanedicarboxylic acid. Among these, from the viewpoint of improving moisture resistance, adipic acid is preferable.

[0027] From the viewpoint of improving moisture resistance, the proportion of the monomer unit derived from the aromatic dicarboxylic acid having no hydrophilic group to the total of the dicarboxylic acid monomer unit B is preferably 20 mol% or more, more preferably 30 mol% or more, still more preferably 40 mol% or more.

[0028] Also, from the viewpoint of imparting dispersibility in neutral water, the proportion of the monomer unit derived from the aromatic dicarboxylic acid having no hydrophilic group to the total of the dicarboxylic acid monomer unit B is preferably 100 mol% or less, more preferably 80 mol% or less, still more preferably 60 mol% or less.

[0029] From the viewpoint of improving moisture resistance, the proportion of the amount of substance of the monomer unit B to the total amount of substance of all monomer units in the crystalline resin having a hydrophilic group is preferably 15 mol% or more, more preferably 25 mol% or more, still more preferably 30 mol% or more, still more preferably 35 mol% or more. From the viewpoint of imparting dispersibility in neutral water, it is preferably 45 mol% or less, more preferably 42 mol% or less, still more preferably 40 mol% or less. In the present specification, the composition of the crystalline resin is measured by the method described in the examples.

[0030] The molar ratio (monomer unit A / monomer unit B) of monomer unit A to monomer unit B in the hydrophilic crystalline resin is preferably 10 / 90 or higher, more preferably 15 / 85 or higher, and even more preferably 20 / 80 or higher, from the viewpoint of providing dispersibility in neutral water, and from the viewpoint of improving moisture resistance, it is preferably 70 / 30 or lower, more preferably 60 / 40 or lower, even more preferably 40 / 60 or lower, and even more preferably 30 / 70 or lower.

[0031] The melting point Tm of the crystalline resin having the hydrophilic group is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher, from the viewpoint of improving heat resistance during use, and preferably 200°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower, from the viewpoint of providing dispersibility in neutral water. In this specification, the melting point Tm of the crystalline resin is measured by the method described in the examples.

[0032] The glass transition temperature of the crystalline resin having the hydrophilic group is preferably -10°C or higher, more preferably -5°C or higher, and even more preferably 0°C or higher, from the viewpoint of improving heat resistance during use, and preferably 180°C or lower, more preferably 100°C or lower, even more preferably 60°C or lower, and even more preferably 50°C or lower, from the viewpoint of imparting dispersibility in neutral water. In this specification, the glass transition temperature of the crystalline resin is measured by the method described in the examples.

[0033] The weight-average molecular weight of the crystalline resin having the hydrophilic group is preferably 1000 or more, more preferably 3000 or more, and even more preferably 4000 or more, from the viewpoint of improving moisture resistance, and preferably 80000 or less, more preferably 50000 or less, and even more preferably 30000 or less, from the viewpoint of imparting dispersibility in neutral water. In this specification, the weight-average molecular weight is measured by the method described in the examples.

[0034] (Diol monomer unit C) If the crystalline resin having the hydrophilic group is a water-soluble polyester resin, it has diol monomer units C other than monomer unit A and monomer unit B. The diol used to derive the diol monomer unit C is also referred to as diol C.

[0035] As the aforementioned diol C, aliphatic diols, aromatic diols, etc., can be used, but from the viewpoint of the ease of obtaining raw materials for water-soluble polyester resins, aliphatic diols are preferred.

[0036] The carbon number of the diol C is preferably 2 or more from the viewpoint of imparting dispersibility in neutral water, preferably 31 or less, more preferably 25 or less, even more preferably 20 or less, and even more preferably 15 or less from the viewpoint of improving moisture resistance.

[0037] The aliphatic diol can be one or more selected from the group consisting of chain-type diols and cyclic diols. From the viewpoint of ease of obtaining raw materials, chain-type diols are preferred, and from the viewpoint of improving water resistance, cyclic diols are preferred.

[0038] The ratio of monomer units derived from the cyclic diol to the total diol monomer units C is preferably 40 ml or more, more preferably 50 ml or more, and even more preferably 60 ml or more, from the viewpoint of imparting dispersibility in neutral water, and preferably 90 ml or less, more preferably 85 ml or less, and even more preferably 80 ml or less, from the viewpoint of the availability of raw materials.

[0039] The number of carbon atoms in the chain-like diol is preferably 2 or more from the viewpoint of improving moisture resistance, preferably 20 or less, more preferably 15 or less, and even more preferably 6 or less from the viewpoint of providing dispersibility in neutral water.

[0040] From the viewpoint of improving moisture resistance and providing dispersibility in neutral water, the chain-type diol is preferably an alkanediol, more preferably one or more selected from the group consisting of ethylene glycol, propanediol, butanediol, neopentyl glycol, pentanediol, hexanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, and polypropylene glycol, even more preferably one or more selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, and triethylene glycol, and even more preferably 1,3-propanediol or ethylene glycol.

[0041] The carbon number of the cyclic diol is preferably 3 or more, more preferably 4 or more, and even more preferably 6 or more, from the viewpoint of improving moisture resistance, and is preferably 31 or less, more preferably 20 or less, and even more preferably 15 or less, from the viewpoint of providing dispersibility in neutral water.

[0042] From the viewpoint of improving moisture resistance and providing dispersibility in neutral water, the cyclic diol is preferably one or more selected from the group consisting of cyclohexanedimethanol, hydrogenated bisphenol A, isosorbide, bisphenoxyethanol fluorene, bisphenol fluorene, biscrezooxyethanol fluorene, and biscresol fluorene, with 1,4-cyclohexanedimethanol being more preferred.

[0043] The water-soluble polyester resin may have monomer units other than the dicarboxylic acid monomer unit A, the dicarboxylic acid monomer unit B, and the diol monomer unit C, to the extent that it does not impair the effects of this embodiment.

[0044] There are no particular limitations on the method for producing the water-soluble polyester resin, and conventionally known methods for producing polyester resins can be applied.

[0045] In the amorphous process, a heat treatment method for the crystalline resin having hydrophilic groups is preferred. That is, the amorphous process preferably includes a heat treatment step for heat treating the crystalline resin having hydrophilic groups.

[0046] The heat treatment temperature of the crystalline resin having hydrophilic groups in the heat treatment step is preferably Tm + 10°C or higher, more preferably Tm + 20°C or higher, and even more preferably Tm + 30°C or higher, relative to the melting point Tm of the crystalline resin having hydrophilic groups, from the viewpoint of efficiently amorphousizing the crystalline resin having hydrophilic groups. From the viewpoint of energy saving, it is preferably Tm + 70°C or lower, more preferably Tm + 60°C or lower, and even more preferably Tm + 50°C or lower.

[0047] The heat treatment temperature of the crystalline resin having hydrophilic groups in the heat treatment step is preferably 110°C or higher, more preferably 120°C or higher, and even more preferably 140°C or higher, from the viewpoint of efficiently amorphousizing the crystalline resin having hydrophilic groups, and from the viewpoint of energy saving, it is preferably 220°C or lower, more preferably 190°C or lower, and even more preferably 160°C or lower.

[0048] The heat treatment time for the crystalline resin having hydrophilic groups in the heat treatment step is preferably 10 seconds or more, more preferably 30 seconds or more, and even more preferably 45 seconds or more, from the viewpoint of efficiently amorphousizing the crystalline resin having hydrophilic groups. Similarly, it is preferably 15 minutes or less, more preferably 10 minutes or less, even more preferably less than 3 minutes, and even more preferably 2 minutes or less.

[0049] In the heat treatment step, the shear rate during the heat treatment of the crystalline resin having hydrophilic groups is preferably 1 cycle / second or less, more preferably 0.1 cycles / second or less, and even more preferably 0.01 cycles / second or less, from the viewpoint of efficiently amorphousizing the crystalline resin having hydrophilic groups.

[0050] In the heat treatment step, when centrifuging the crystalline resin having hydrophilic groups while heating it, the extrusion speed is preferably 100 m / min or less, more preferably 10 m / min or less, even more preferably 1 m / min or less, and even more preferably 0.1 m / min or less, from the viewpoint of efficiently amorphousizing the crystalline resin having hydrophilic groups.

[0051] In the heat treatment step described above, the heat treatment of the crystalline resin having hydrophilic groups is preferably carried out under shear-free conditions, in order to efficiently amorphous the crystalline resin having hydrophilic groups, without applying shear to the crystalline resin having hydrophilic groups.

[0052] The heat treatment means in the heat treatment step is not particularly limited, and known general heat treatment methods can be used.

[0053] <Method for dispersing a crystalline resin having hydrophilic groups in neutral water> The method for dispersing a hydrophilic crystalline resin in neutral water according to this embodiment (hereinafter also simply referred to as the dispersion method) is a method in which the water dispersibility of the hydrophilic crystalline resin is improved by the water dispersibility improvement method, and then the hydrophilic crystalline resin is dispersed in neutral water.

[0054] One example of the dispersion method is to bring the crystalline resin having the hydrophilic group into contact with the neutral water.

[0055] In the dispersion method described above, the amount of neutral water used is preferably 10 times or more by mass relative to the crystalline resin having hydrophilic groups, more preferably 20 times or more by mass, from the viewpoint of dispersing the crystalline resin having hydrophilic groups, and from the viewpoint of reducing environmental impact, it is preferably 10,000 times or less by mass relative to the crystalline resin having hydrophilic groups, more preferably 5,000 times or less by mass, even more preferably 1,000 times or less by mass, and even more preferably 100 times or less by mass.

[0056] In the dispersion method described above, the time for which the crystalline resin having hydrophilic groups is in contact with water is preferably 5 minutes or more from the viewpoint of dispersing the crystalline resin having hydrophilic groups, preferably 30 minutes or less from the viewpoint of energy saving, more preferably 20 minutes or less, and even more preferably 10 minutes or less.

[0057] In the dispersion method described above, the temperature of the neutral water is preferably 30°C or higher, more preferably 40°C or higher, from the viewpoint of dispersing the crystalline resin having the hydrophilic group, and preferably 70°C or lower, more preferably 60°C or lower, from the viewpoint of reducing environmental impact.

[0058] The crystalline resin having hydrophilic groups may be a used resin. When the crystalline resin having hydrophilic groups is contained in a printed material, adhesive, sealant, or coating, the printed material, adhesive, sealant, or coating containing the crystalline resin having hydrophilic groups can be removed by the water dispersibility improvement method or the dispersion method.

[0059] <How to remove printed matter> The printing removal method of this embodiment includes a method for improving the dispersibility of the hydrophilic crystalline resin in neutral water, or a method for dispersing the hydrophilic crystalline resin in neutral water.

[0060] <Method for removing adhesive> The adhesive removal method of this embodiment includes a method for improving the dispersibility of the hydrophilic crystalline resin in neutral water, or a method for dispersing the hydrophilic crystalline resin in neutral water.

[0061] <Method for removing adhesive> The adhesive removal method of this embodiment includes a method for improving the dispersibility of the hydrophilic crystalline resin in neutral water, or a method for dispersing the hydrophilic crystalline resin in neutral water.

[0062] <Coating removal method> The coating removal method of this embodiment includes a method for improving the dispersibility of the hydrophilic crystalline resin in neutral water, or a method for dispersing the hydrophilic crystalline resin in neutral water.

[0063] This specification further discloses the following embodiments.

[0064] <1> A method for improving the dispersibility of a crystalline resin having hydrophilic groups in neutral water, comprising an amorphous step of amorphousizing the crystalline resin having hydrophilic groups. <2> The melting point Tm of the crystalline resin having the hydrophilic group is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher. <1> Methods used. <3> The melting point Tm of the crystalline resin having the hydrophilic group is preferably 200°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower. <1> or <2> Methods used. <4> The glass transition temperature of the crystalline resin having the hydrophilic group is preferably -10°C or higher, more preferably -5°C or higher, and even more preferably 0°C or higher. <1> ~ <3> One of the methods described above. <5> The glass transition temperature of the crystalline resin having the hydrophilic group is preferably 100°C or lower, more preferably 60°C or lower, and even more preferably 50°C or lower. <1> ~ <4> One of the methods described above. <6> The content of the hydrophilic group in the crystalline resin having the hydrophilic group is preferably 0.4 mmol / g or more, more preferably 0.6 mmol / g or more, and even more preferably 0.7 mmol / g or more. <1> ~ <5> One of the methods described above. <7> The content of the hydrophilic groups in the crystalline resin having the hydrophilic groups is preferably 3.0 mmol / g or less, more preferably 2.0 mmol / g or less, even more preferably 1.5 mmol / g or less, and even more preferably 1.0 mmol / g or less. <1> ~ <6> One of the methods described above. <8> The crystalline resin having hydrophilic groups is a crystalline water-soluble resin having monomer units A having hydrophilic groups and monomer units B not having hydrophilic groups. <1> ~ <7> One of the methods described above. <9> The molar ratio of monomer unit A to monomer unit B in the hydrophilic crystalline resin (monomer unit A / monomer unit B) is preferably 10 / 90 or more, more preferably 15 / 85 or more, and even more preferably 20 / 80 or more. <1> ~ <8> One of the methods described above. <10> The molar ratio (monomer unit A / monomer unit B) of monomer unit A to monomer unit B in the hydrophilic crystalline resin is preferably 70 / 30 or less, more preferably 60 / 40 or less, even more preferably 40 / 60 or less, and even more preferably 30 / 70 or less. <1> ~ <9> One of the methods described above. <11> The weight-average molecular weight of the crystalline resin having the hydrophilic group is preferably 1000 or more, more preferably 3000 or more, and even more preferably 4000 or more. <1> ~ <10> One of the methods described above. <12> The weight-average molecular weight of the crystalline resin having the hydrophilic group is preferably 80,000 or less, more preferably 50,000 or less, and even more preferably 30,000 or less. <1> ~ <11> One of the methods described above. <13> The amorphous process includes a heat treatment process in which the crystalline resin having the hydrophilic group is heat-treated. <1> ~ <12> One of the methods described above. <14> In the heat treatment step, the heat treatment of the crystalline resin having hydrophilic groups is performed under shear-free conditions. <13> Methods used. <15> The heat treatment temperature of the crystalline resin having hydrophilic groups in the heat treatment step is preferably Tm+10°C or higher, more preferably Tm+20°C or higher, and even more preferably Tm+30°C or higher, relative to the melting point Tm of the crystalline resin having hydrophilic groups. <13> or <14> Methods used. <16> The heat treatment temperature of the hydrophilic crystalline resin in the heat treatment step is preferably Tm + 70°C or lower, more preferably Tm + 60°C or lower, and even more preferably Tm + 50°C or lower, relative to the melting point Tm of the hydrophilic crystalline resin. <13> ~ <15> One of the methods described above. <17> The heat treatment temperature of the crystalline resin having hydrophilic groups in the heat treatment step is preferably 110°C or higher, more preferably 120°C or higher, and even more preferably 140°C or higher. <13> ~ <16> One of the methods described above. <18> The heat treatment temperature of the crystalline resin having hydrophilic groups in the heat treatment step is preferably 220°C or lower, more preferably 190°C or lower, and even more preferably 160°C or lower. <13> ~ <17> One of the methods described above. <19> The hydrophilic group is preferably one or more selected from the group consisting of anionic groups, and more preferably a sulfonic acid base. <1> ~ <18> One of the methods described above. <20> The crystalline resin having the hydrophilic group is a water-soluble polyester resin. <1> ~ <19> One of the methods described above. <21> The process includes an amorphous step to make a crystalline resin having hydrophilic groups amorphous, The melting point Tm of the crystalline resin having the hydrophilic group is 70°C or higher and 200°C or lower. The glass transition temperature of the crystalline resin having the hydrophilic group is -10°C or higher and 100°C or lower. The content of the hydrophilic group in the crystalline resin having the hydrophilic group is 0.4 mmol / g or more and 3.0 mmol / g or less. The crystalline resin having hydrophilic groups is a crystalline water-soluble resin having monomer units A having hydrophilic groups and monomer units B not having hydrophilic groups. The molar ratio (monomer unit A / monomer unit B) of monomer unit A to monomer unit B in the hydrophilic crystalline resin is 10 / 90 or more and 70 / 30 or less. The weight-average molecular weight of the crystalline resin having the hydrophilic group is 1,000 or more and 80,000 or less. The amorphous process includes a heat treatment process in which the crystalline resin having the hydrophilic group is heat-treated. The heat treatment process described above is carried out under shear-free conditions. The heat treatment temperature of the hydrophilic crystalline resin in the heat treatment step is between Tm+10°C and Tm+70°C relative to the melting point Tm of the hydrophilic crystalline resin. The hydrophilic group is a sulfonic acid base, A method for improving the dispersibility of a hydrophilic crystalline resin in neutral water, wherein the hydrophilic crystalline resin is a water-soluble polyester. <22> The crystalline resin having the hydrophilic group is a used resin. <1> ~ <21> One of the methods described above. <23> The crystalline resin having the hydrophilic group is contained in printed materials, adhesives, sealants, or coatings. <1> ~ <22> One of the methods described above. <24> <1> ~ <23> A method for improving the dispersibility of a hydrophilic crystalline resin in neutral water by any of the methods described above, and then dispersing the hydrophilic crystalline resin in neutral water. <25> <1> ~ <24> A method for removing a coating, comprising the method described in any of the following. [Examples]

[0065] Pressure is expressed in absolute pressure. "Normal pressure" refers to 101.3 kPa.

[0066] <Examples of synthesis of crystalline resins containing hydrophilic groups> [Example of synthesis of crystalline resin 1 having hydrophilic groups] In a 2L stainless steel flask with a separable lid, 120.00g of dimethyl terephthalic acid (manufactured by SK Oil & Chemical Co., Ltd.), 107.64g of dimethyl adipic acid (manufactured by Tokyo Chemical Industries, Ltd.), 109.83g of dimethyl sodium 5-sulfoisophthalate (manufactured by Sanyo Chemical Industries, Ltd.), 174.66g of 1,4-cyclohexanedimethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 124.13g of 1,3-propanediol (manufactured by Tokyo Chemical Industries, Ltd.), 252.4mg of tetrabutyl orthotitanate (manufactured by Tokyo Chemical Industries, Ltd.), and 675.7mg of sodium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added. A nitrogen inlet tube, anchor-type stirring blade, Dean-Stark tube, and Liebig condenser were attached, and the flask was placed inside a mantle heater. The flask was heated with a nitrogen flow rate of 0.5L / min and under atmospheric pressure while stirring until the flask wall temperature reached 160°C. Subsequently, the temperature was raised to 220°C over 25 minutes, and the reaction was carried out at atmospheric pressure for 6.5 hours while removing the resulting distillate from the Dean-Stark apparatus. Then, the temperature was raised to 240°C over 20 minutes while the pressure was reduced to 1.5 kPa, and the reaction was carried out for another 6.5 hours while removing the resulting distillate. The mixture was allowed to cool to room temperature, yielding 438.68 g of hydrophilic crystalline resin 1.

[0067] [Example of synthesis of crystalline resin 2 having hydrophilic groups] The reaction was carried out under the same conditions as the synthesis example of crystalline resin 1, except that the raw materials listed in Table 1 were used and the reaction was carried out for 5.5 hours while removing the resulting distillate after reducing the pressure to 1.5 kPa, yielding 396.39 g of crystalline resin 2 having hydrophilic groups.

[0068] [Example of synthesis of crystalline resin 3 having hydrophilic groups] The reaction was carried out under the same conditions as the synthesis example of crystalline resin 1, except that the raw materials listed in Table 1 were used and the reaction was carried out for 6 hours while removing the resulting distillate after reducing the pressure to 1.5 kPa, yielding 378.84 g of crystalline resin 3 having hydrophilic groups.

[0069] [Example of synthesis of crystalline resin 4 having hydrophilic groups] The reaction was carried out under the same conditions as the synthesis example of crystalline resin 1, except that the raw materials listed in Table 1 were used and the reaction was carried out for 8.5 hours while removing the resulting distillate after reducing the pressure to 1.5 kPa, yielding 400.06 g of crystalline resin 4 having hydrophilic groups.

[0070] [Example of synthesis of crystalline resin 5 having hydrophilic groups] The reaction was carried out under the same conditions as the synthesis example of crystalline resin 1, except that the raw materials listed in Table 1 were used and the reaction was carried out for 6.5 hours while removing the resulting distillate after reducing the pressure to 1.5 kPa, yielding 412.94 g of the crystalline resin 5 having hydrophilic groups.

[0071] [Example of synthesis of crystalline resin 6 having hydrophilic groups] The reaction was carried out under the same conditions as the synthesis example of crystalline resin 1, except that the raw materials listed in Table 1 were used and the reaction was carried out for 3 hours while removing the resulting distillate after reducing the pressure to 1.5 kPa, yielding 286.81 g of crystalline resin 6 having hydrophilic groups.

[0072] [Example of synthesis of crystalline resin 7 having hydrophilic groups] The reaction was carried out under the same conditions as the synthesis example of crystalline resin 1, except that the raw materials listed in Table 1 were used and the reaction was carried out for 15.5 hours while removing the resulting distillate after reducing the pressure to 1.5 kPa, yielding 274.41 g of crystalline resin 7 having hydrophilic groups.

[0073] [Example of synthesis of crystalline resin 8 having hydrophilic groups] The reaction was carried out under the same conditions as the synthesis example of crystalline resin 1, except that the raw materials listed in Table 1 were used and the reaction was carried out for 8 hours while removing the resulting distillate after reducing the pressure to 1.5 kPa, yielding 321.71 g of crystalline resin 8 having hydrophilic groups.

[0074] [Example of synthesis of crystalline resin 9 having hydrophilic groups] The reaction was carried out under the same conditions as the synthesis example of crystalline resin 1, except that the raw materials listed in Table 1 were used and the reaction was carried out for 7 hours while removing the resulting distillate after reducing the pressure to 1.5 kPa, yielding 362.20 g of crystalline resin 9 having hydrophilic groups.

[0075] [Table 1]

[0076] The terms used in Table 1 have the following meanings: DMT: Dimethyl terephthalate (manufactured by SK Oil & Fat Chemical Co., Ltd.) NDCM: 2,6-Dimethyl naphthalenedicarboxylate (manufactured by Indorama) DMA: Dimethyladipic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) DMSeb: Dimethyl sebacate (manufactured by Tokyo Chemical Industry Co., Ltd.) DMSuc: Dimethyl succinate (manufactured by Tokyo Chemical Industry Co., Ltd.) SID: Dimethyl sodium 5-sulfisophthalate (manufactured by Sanyo Chemical Industries, Ltd.) EG: Ethylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 1,3-PD:1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) 1,4-CHDM: 1,4-Cyclohexanedimethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) AcONa: Sodium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Ti(OBu)4: Tetrabutyl orthotitanate (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0077] <Evaluation Method> [The ratio of the amount of monomer units derived from dimethyl sodium 5-sulfoisophthalate (monomer unit A) to the total amount of monomer units in a hydrophilic crystalline resin.] Ten mg of hydrophilic crystalline resin was dissolved in a solvent prepared by mixing deuterated chloroform and deuterated trifluoroacetic acid in a mass ratio of 3:2, and proton NMR was measured using an Agilent MR400 NMR spectrometer. The amount of substance A was calculated by dividing the integral value A of the peak derived from the proton directly bonded to the aromatic ring in the monomer unit derived from sodium 5-sulfoisophthalate (monomer unit A) by the number of protons directly bonded to the aromatic ring in monomer unit A. The amount of substance B1 was calculated by dividing the integral value B1 of the peak derived from the proton directly bonded to the aromatic ring in the monomer unit derived from aromatic dimethyl dicarboxylate without hydrophilic groups (monomer unit B1) by the number of protons directly bonded to the aromatic ring in monomer unit B1. The amount of substance B2 was calculated by dividing the integral value B2 of the peak derived from the proton directly bonded to the alpha position of the ester in the monomer unit derived from aliphatic dimethyl dicarboxylate without hydrophilic groups (monomer unit B2) by the number of protons directly bonded to the alpha position in monomer unit B2. The amount of substance A was divided by twice the sum of the amounts of substance A, B1, and B2, and expressed as a percentage (100 × amount of substance A / (2 × (amount of substance A + amount of substance B1 + amount of substance B2))), which was used as the ratio of the amount of substance of monomer unit A to the total amount of substance of all monomer units in the hydrophilic crystalline resin. The results are shown in Table 1.

[0078] [Measurement of weight-average molecular weight] A crystalline resin containing hydrophilic groups was dissolved in dimethylformamide to a concentration of 0.1% by mass. Calibration curves were then prepared from standard polystyrene using gel permeation chromatography (GPC) under the following conditions, and the weight-average molecular weight (Mw) was determined. The results are shown in Table 1. [Measurement conditions] Equipment: HLC-8320GPC (manufactured by Tosoh Corporation, with integrated detector) Column: α-M x 2 (manufactured by Tosoh Corporation, 7.8mm ID x 30cm) Eluent: Mixture of 60 mmol / L phosphoric acid and 50 mmol / L lithium dimethylformamide brominated Flow rate: 1.0 mL / min, Column temperature: 40°C Detector: RI detector Standard material: Polystyrene

[0079] [Sample preparation method for DSC and wide-angle X-ray measurement] A dispersion of crystalline resin containing 10% by mass of hydrophilic groups was heated and dried on a hot plate (Digital Hotplate NINOS ND-1, AS ONE) heated to 70°C, and then dried under reduced pressure at 70°C using a vacuum dryer (VACUUM OVEN VOS-451SD, Tokyo Rikakikai Co., Ltd.). The resulting resin was pulverized to obtain crystallized crystalline resin powder. The obtained crystalline resin powder was heated on a hot plate at 150°C for 10 minutes to obtain resin powder after amorphous treatment.

[0080] [Glass transition temperature] 5-10 mg of sample was accurately weighed and sealed in an aluminum pan. Using a DSC instrument (Seiko Instruments DSC7020), the temperature was increased from 30°C to 230°C at a rate of 10°C / min, and then cooled to 30°C at a cooling rate of 150°C / min. The glass transition temperature (°C) was determined from the DSC curve obtained by again increasing the temperature to 230°C at a rate of 10°C / min. The results are shown in Table 1.

[0081] [Measuring the melting point (DSC) of crystalline resins containing hydrophilic groups] 5 mg of crystalline resin powder was placed in an aluminum pan (GAA-0065, GAA-0064, Hitachi High-Tech Science Co., Ltd.), and the temperature was varied from -60°C to 230°C, -30°C, and 230°C using a differential scanning calorimeter (DSC7020, Hitachi High-Tech Science Co., Ltd.) at a scanning speed of 10°C / min. The temperature of the peak at the melting point that occurred in the first run was defined as the melting point of the crystalline resin containing hydrophilic groups. The results are shown in Table 1.

[0082] [Confirmation of crystals (wide-angle X-ray measurement)] Each crystalline resin powder, or resin powder obtained by amorphous treatment of each crystalline resin at the temperatures and times described in Tables 2, 4, or 5, was placed on a glass plate and measured in a wide-angle X-ray measuring device Mini Flex II (manufactured by Rigaku) ​​at 32kV, 15mA, and a scanning speed of 1° / min. The presence or absence of crystals in the resins of Examples 1-18 and Comparative Examples 1-9 was confirmed by the presence or absence of peaks around diffraction angles 2θ of 17° and 23°. The measurement results are shown in Tables 2-5.

[0083] [Evaluation of the solubility of crystalline resins containing hydrophilic groups] [Creating evaluation samples] To 16 g of deionized water heated to 70°C using a hot stirrer (AS ONE, HS-7BHSD), 4.0 g of hydrophilic crystalline resin was added and stirred until all solids were dispersed. The heating was then stopped and the mixture was allowed to cool to room temperature to prepare a 20% by mass dispersion of hydrophilic crystalline resin. The prepared hydrophilic crystalline resin dispersion was coated onto the corona-treated surface of a single-sided corona-treated PET film (Futamura Chemical Co., Ltd., FE2001#25) using gravure solid printing on a desktop gravure printer (Matsuo Sangyo Co., Ltd., K Printing Proofer). The film was then heated to 90°C on a hot plate (AS ONE, Digital Hotplate NINOS ND-1) and held for 5 minutes to dry, obtaining a PET film with a coating containing hydrophilic crystalline resin. Furthermore, the crystalline resin 10 was prepared by letting the dispersion stand for 24 hours, removing the small amount of insoluble material that resulted, and then coating the supernatant portion onto the PET film.

[0084] [Amorphization treatment] A PET film having a coating containing a hydrophilic crystalline resin was placed on a hot plate heated to the temperature specified in Table 2, 4, or 5, and heated for the time specified in Table 2, 4, or 5 to amorphousize the crystalline resins 1 to 10, thereby obtaining evaluation samples related to Examples 1 to 18.

[0085] [pH of neutral water] Tap water was used as the neutral water for the evaluation of the removal efficiency described below. Tap water (neutral water) was collected in a beaker, and the pH was measured using a glass electrode under the following conditions. The pH was 7.44. Tap water (neutral water) temperature: 23℃ Glass electrode: 9615S-10D (manufactured by HORIBA) pH meter: F-72 (manufactured by HORIBA) The above procedure was performed after calibrating the pH and glass electrode using standard buffer (phthalate pH buffer) pH 4.01 (25°C) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), standard buffer (neutral phosphate pH buffer) pH 6.86 (25°C) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and standard buffer (borate pH buffer) pH 9.18 (25°C) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0086] [Evaluation of removal efficiency using neutral water] (Examples 1-17, Comparative Examples 1-9) Evaluation samples (2cm x 2cm) for Examples 1-17 and Comparative Examples 1-9 were attached to a glass slide (S2112, 76mm x 26mm, manufactured by Matsunami Glass Industry Co., Ltd.) using double-sided tape. The edges of the glass slide were clipped and suspended, and the PET film was placed in a 500mL beaker containing 400mL of tap water (neutral water) at the temperatures listed in Tables 2-4, which was being stirred by a magnetic stirrer, ensuring that the PET film was completely submerged in the water. The time it took for the coating containing hydrophilic crystalline resin on the film to be completely removed was defined as the deinking time. If the coating was not removed after 120 minutes in the water, it was evaluated as "no deinking." The evaluation results are shown in Tables 2-4.

[0087] [Table 2]

[0088] [Table 3]

[0089] [Table 4]

[0090] (Example 18, Comparative Example 10) In the same manner as in Example 1, the PET film was placed so that it was completely submerged in 70°C water. After 120 minutes, the coating remained intact in all evaluation samples. The evaluation samples were removed, and the ink's delamination properties were evaluated by rubbing the surface with rubber gloves. The evaluation results are shown in Table 5.

[0091] [Table 5]

Claims

1. A method for improving the dispersibility of a crystalline resin having a sulfonic acid base in neutral water, comprising an amorphous step of amorphousizing the crystalline resin having a sulfonic acid base, The content of the sulfonic acid base in the crystalline resin is 0.4 mmol / g or more and 3.0 mmol / g or less. A method wherein the crystalline resin is a polyester resin.

2. The method according to claim 1, wherein the melting point Tm of the crystalline resin is 70°C or higher and 200°C or lower.

3. The method according to claim 1, wherein the glass transition temperature of the crystalline resin is -10°C or higher and 180°C or lower.

4. The method according to claim 1, wherein the crystalline resin comprises monomer unit A having a sulfonic acid base and monomer unit B not having a hydrophilic group.

5. The method according to claim 4, wherein the mol ratio (monomer unit A / monomer unit B) of monomer unit A to monomer unit B in the crystalline resin is 10 / 90 or more and 70 / 30 or less.

6. The method according to claim 1, wherein the weight-average molecular weight of the crystalline resin is 1,000 or more and 80,000 or less.

7. The method according to claim 1, wherein the amorphous step comprises a heat treatment step of heat-treating the crystalline resin.

8. The method according to claim 7, wherein the heat treatment of the crystalline resin in the heat treatment step is performed under shear-free conditions.

9. The method according to claim 7, wherein the heat treatment temperature of the crystalline resin in the heat treatment step is Tm + 10°C or more and Tm + 70°C or less with respect to the melting point Tm of the crystalline resin.

10. The method according to claim 7, wherein the heat treatment temperature of the crystalline resin in the heat treatment step is 110°C or more and 220°C or less.

11. The method according to claim 1, wherein the crystalline resin is a used resin.

12. The method according to claim 1, wherein the crystalline resin is contained in a printed material, adhesive, sealant, or coating.

13. A method for improving the dispersibility of the crystalline resin in neutral water by the method described in any one of claims 1 to 12, and then dispersing the crystalline resin in neutral water.

14. A method for removing a coating, comprising the method according to any one of claims 1 to 12.

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