JP7786389B2 - Ester compound, method for synthesizing ester compound, and resin composition - Google Patents

Description

The present disclosure relates to ester compounds, methods for synthesizing ester compounds, and resin compositions.

Photosoftenable compositions that soften upon exposure to light are used in a variety of applications. For example, Patent Document 1 discloses an image-forming device equipped with a recording member having a photosoftenable resin layer made of a photosoftenable resin.

Japanese Patent Application Publication No. 11-190883

The present disclosure aims to provide a novel ester compound having photosoftening properties, a method for synthesizing the ester compound, and a resin composition that softens upon exposure to light.

One aspect of the present disclosure relates to an ester compound that is a transesterification reaction product of a dicarboxylic acid ester having a disulfide bond and a polyol, and that has a disulfide bond in the molecular chain and a hydroxy group at the end.

Another aspect of the present disclosure relates to a method for synthesizing an ester compound, which comprises transesterifying a dicarboxylic acid ester having a disulfide bond with a polyol to obtain an ester compound having a disulfide bond in the molecular chain and a hydroxyl group at the end.

Another aspect of the present disclosure relates to a resin composition containing the above-mentioned ester compound and a photoradical generator.

The present disclosure provides a novel ester compound having photosoftening properties, a method for synthesizing the ester compound, and a resin composition that softens upon exposure to light.

The following describes embodiments of the present disclosure. However, the present disclosure is not limited to the following embodiments.

As used herein, "photosoftening" refers to properties such as a decrease in viscosity, a decrease in modulus of elasticity, an increase in loss tangent (tan δ), or a decrease in hardness upon exposure to light. The term "process" as used herein includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved. Numerical ranges indicated using "to" in this specification indicate ranges that include the numerical values before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of a numerical range in another stage. In numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with the values shown in the examples. Individually described upper and lower limits may be combined in any combination.

In this specification, the content of each component in a composition means the total amount of those components present in the composition, unless otherwise specified, when the composition contains multiple substances corresponding to that component. Furthermore, unless otherwise specified, exemplified materials may be used alone or in combination of two or more. "A or B" means that either A or B is present, or both may be present.

[Ester compounds]
The ester compound according to the present embodiment is a photosoftenable resin that is a product of an ester exchange reaction between a dicarboxylic acid ester having a disulfide bond and a polyol, and that has a disulfide bond in the molecular chain and a hydroxyl group at the terminal. Such an ester compound can be obtained by an ester exchange reaction between a dicarboxylic acid ester having a disulfide bond and a polyol.

Compounds containing hydroxy groups and disulfide bonds are known to be obtained by a Michael addition reaction between a thiol compound containing a disulfide bond and an acrylate compound containing a hydroxyl group. Compounds containing hydroxy groups and disulfide bonds obtained by a Michael addition reaction have a thioether bond derived from the thiol group. In contrast, the ester compound of this embodiment differs from compounds containing hydroxy groups and disulfide bonds obtained by a Michael addition reaction at least in that it does not have a thioether bond. Furthermore, compared to a Michael addition reaction, a transesterification reaction makes it easier to control the molecular weight and can stably obtain the desired ester compound.

The hydroxyl value of the ester compound may be 20 to 150 mgKOH/g, 20 to 140 mgKOH/g, or 25 to 120 mgKOH/g. The hydroxyl value can be measured in accordance with JIS K0070.

(Dicarboxylic acid ester having a disulfide bond)
The dicarboxylic acid ester having a disulfide bond is a compound having a disulfide bond capable of generating a thiyl radical upon irradiation with light and an alkyl ester group capable of transesterification. For example, a compound having a structure represented by the following formula (1) can be used as the dicarboxylic acid ester having a disulfide bond:
R ¹ -O-C(=O)-R ³ -S-S-R ⁴ -C(=O)-O-R ² (1)

In formula (1), ^R1 and ^R2 each independently represent an alkyl group having 1 to 4 carbon atoms, and ^R3 and ^R4 each independently represent an alkylene group having 1 to 10 carbon atoms. ^R1 and ^R2 are preferably alkyl groups having 1 to 3 carbon atoms, more preferably methyl groups or ethyl groups, and even more preferably methyl groups, in view of the ease with which the transesterification reaction proceeds. ^R3 and ^R4 may each be an alkylene group having 1 to 8 carbon atoms, an alkylene group having 2 to 6 carbon atoms, or an alkylene group having 2 to 4 carbon atoms.

Examples of dicarboxylic acid esters having a disulfide bond include dimethyl 3,3'-dithiopropionate, dimethyl dithiodiacetate, and dimethyl 4,4'-dithiodibutyrate. The dicarboxylic acid ester according to this embodiment may contain at least one selected from the group consisting of dimethyl 3,3'-dithiopropionate, dimethyl dithiodiacetate, and dimethyl 4,4'-dithiodibutyrate.

(Polyol)
The polyol can be used without any particular limitation as long as it is a compound having two or more hydroxy groups. The polyol may be a compound (diol) having two hydroxy groups. Examples of polyols include polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, polybutadiene polyols, and bisphenol A-ethylene oxide addition diols. The polyol according to this embodiment may include at least one selected from the group consisting of polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, polybutadiene polyols, and bisphenol A-ethylene oxide addition diols.

Examples of polyether polyols include polytetramethylene ether glycol, polyethylene glycol, and polypropylene glycol.

In the method for synthesizing an ester compound according to this embodiment, an ester compound having a disulfide bond in the molecular chain and a hydroxyl group at the terminal can be obtained by transesterification of a dicarboxylic acid ester having a disulfide bond with a polyol.

When synthesizing an ester compound, the blending ratio of dicarboxylic acid ester to polyol is preferably adjusted so that the molar ratio of alkyl ester groups in the dicarboxylic acid ester is in the range of 0.5 to 0.9 moles per mole of hydroxyl groups in the polyol. This makes it easier to obtain an ester compound with a terminal hydroxyl group and to adjust the proportion and molecular weight of disulfide bonds in the ester compound.

When synthesizing an ester compound, a catalyst may be used to promote the transesterification reaction. The catalyst is not particularly limited, as long as it is a compound commonly used in transesterification reactions. Examples of catalysts include titanium compounds and acetate compounds. An example of a titanium compound is titanium tetraisopropoxide.

The temperature and time of the ester exchange reaction are not particularly limited, and the temperature may be approximately 25 to 120°C, and the time of the ester exchange reaction may be approximately 1 to 20 hours.

[Resin composition]
The resin composition according to this embodiment contains the above-described ester compound and a photoradical generator.

(Photoradical generator)
The photoradical generator may be a component that reacts with a thiyl radical generated when the resin composition is irradiated with light or a component that generates a photoinduced radical. Examples of the photoradical generator that can be used include a photoradical polymerization initiator.

Examples of photoradical generators include intramolecular cleavage-type photoradical polymerization initiators and hydrogen abstraction-type photoradical polymerization initiators. Examples of intramolecular cleavage-type photoradical polymerization initiators include benzyl ketal-based photoradical polymerization initiators; α-hydroxyacetophenone-based photoradical polymerization initiators; benzoin-based photoradical polymerization initiators; aminoacetophenone-based photoradical polymerization initiators; oxime ketone-based photoradical polymerization initiators; acylphosphine oxide-based photoradical polymerization initiators; titanocene-based photoradical polymerization initiators; S-phenyl thiobenzoate polymerization initiators; and high molecular weight derivatives thereof. Examples of hydrogen abstraction-type photoradical polymerization initiators include benzophenone-based photoradical polymerization initiators, thioxanthone-based photoradical polymerization initiators, and anthraquinone-based photoradical polymerization initiators.

The content of the photoradical generator may be 1 part by mass or more, 5 parts by mass or more, or 8 parts by mass or more, and may be 25 parts by mass or less, 20 parts by mass or less, or 15 parts by mass or less, per 100 parts by mass of the ester compound.

(Polyisocyanate)
The resin composition according to the present embodiment may further contain a polyisocyanate. The polyisocyanate may be any compound having two or more isocyanate groups without any particular limitation. The polyisocyanate may be a compound having two isocyanate groups (diisocyanate).

Examples of polyisocyanates include aromatic isocyanates such as diphenylmethane diisocyanate (4,4'-diphenylmethane diisocyanate), dimethyldiphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and p-phenylene diisocyanate; alicyclic isocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate; aliphatic isocyanates such as hexamethylene diisocyanate; and derivatives and polynuclear compounds derived from these isocyanates, such as isocyanurates, biurets, allophanates, uretdiones, and polymerics. Polyisocyanates may be used alone or in combination of two or more.

The polyisocyanate content may be 10 parts by mass or more, 15 parts by mass or more, or 20 parts by mass or more, and may be 50 parts by mass or less, 40 parts by mass or less, or 30 parts by mass or less, per 100 parts by mass of the ester compound.

The resin composition may further contain other components in addition to the components described above. Examples of other components include thermosetting resins such as epoxy resins, adhesion improvers such as coupling agents, and additives such as polymerization inhibitors, light stabilizers, antifoaming agents, fillers, chain transfer agents, thixotropy-imparting agents, flame retardants, mold release agents, surfactants, lubricants, and antistatic agents. Known other components can be used. The total content of the other components may be 0 to 95% by mass, 0.01 to 50% by mass, or 0.1 to 10% by mass, based on the total amount of the resin composition.

The resin composition may be diluted with a solvent and used as a varnish. Examples of solvents include aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene, and p-cymene; aliphatic hydrocarbons such as hexane and heptane; cyclic alkanes such as methylcyclohexane; cyclic ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and 4-hydroxy-4-methyl-2-pentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, and gamma-butyrolactone; carbonates such as ethylene carbonate and propylene carbonate; and amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone (NMP). Solvents may be used alone or in combination.

The solid component concentration in the varnish may be 10 to 80% by weight, based on the total weight of the varnish.

The resin composition can be prepared, for example, by mixing or kneading the ester compound, photoradical generator, and any other components added as needed. Mixing and kneading can be carried out using an appropriate combination of dispersing machines such as a conventional mixer, a mortar and pestle, a three-roll mill, a ball mill, or a bead mill.

The resin composition according to this embodiment can be formed into a film and used as a photosoftenable resin film. It can also be formed into a block and used as a photosoftenable resin block. There are no particular restrictions on the method for forming the resin composition into a film or block, and known methods can be used.

The resin composition of this embodiment has the property that, upon light irradiation, the disulfide bonds (-S-S-) in the ester compound are cleaved, causing the compound having the disulfide bond to undergo molecular weight reduction and soften. The resin composition can also be softened to a liquid state. Furthermore, the resin composition has the property of being easily molded into a film or block shape. By utilizing these properties, the resin composition of this embodiment can be applied, for example, to photolithography photoresist agents, and can be used as a photosensitive resin composition or a photosensitive resin film. The photosensitive resin composition or photosensitive resin film can be patterned by light irradiation (exposure), and can further be developed by washing with water after light irradiation (exposure). The resin composition of this embodiment can be suitably used to form patterned films.

The resin composition of this embodiment can also be used in a variety of applications, such as a softener or easy-release agent for strong adhesive tapes; an adhesive for weakly adhesive or non-adhesive films; a partial softener for coating materials, adhesives, or adhesives; a partial softener for molding materials; an ultra-low elasticity film that can be punched and obtained by irradiating it with light after punching; a moisture-proofing agent; a capsule coating that softens and dissolves when irradiated with light; and a thickener that reduces viscosity when irradiated with light.

A softened resin composition can be obtained by irradiating the resin composition according to the embodiment with light. The light used for light irradiation is not particularly limited, and may be, for example, ultraviolet light or visible light. The wavelength of the light used for light irradiation may be 150 to 830 nm. Light irradiation can be carried out, for example, using a light irradiation device under conditions of an irradiation dose of 100 mJ/ ^cm2 or more. The irradiation dose refers to the product of illuminance and irradiation time (seconds). Examples of light sources for irradiating ultraviolet light or visible light include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, metal halide lamps, and LED lamps. Light irradiation may be carried out directly on the photosoftenable resin composition or through glass or the like.

The resin composition may be irradiated with light while being heated. Heating conditions may be, for example, 40 to 200°C.

The present disclosure will be explained in more detail below using examples. However, the present disclosure is not limited to these examples.

[Ester compounds]
Example 1
A flask equipped with a stirrer, thermometer, reflux condenser, pressure reducing equipment, and nitrogen inlet piping was prepared. 800 parts by mass of polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., trade name "PEG-400", molecular weight 400) and 238 parts by mass of dimethyl 3,3'-dithiodipropionate (manufactured by Fujifilm Wako Chemical Co., Ltd.) were charged into the flask, and the liquid phase was bubbled with nitrogen and stirred at 90°C for 2 hours while the pressure was reduced to 70 kPa. Next, 10 parts by mass of titanium tetraisopropoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the bubbling and reduced pressure were maintained while stirring at 100°C for 5 hours to carry out a transesterification reaction. This produced an ester compound A having a hydroxy group and a disulfide bond (hydroxyl value: 108 mg KOH/g).

Example 2
2,000 parts by mass of polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., trade name "PEG-2000", molecular weight 2,000) and 119 parts by mass of dimethyl 3,3'-dithiodipropionate were charged into a flask similar to that of Example 1, and the mixture was stirred at 90°C for 2 hours while bubbling nitrogen into the liquid phase and reducing the pressure to 70 kPa. Next, 22 parts by mass of titanium tetraisopropoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred at 100°C for 12 hours while maintaining the bubbling and reduced pressure, to carry out a transesterification reaction. This produced an ester compound B having a hydroxy group and a disulfide bond (hydroxyl value: 27 mgKOH/g).

[Resin composition]
Example 3
A resin composition was prepared by mixing 100 parts by mass of ester compound A and 10 parts by mass of a photoradical generator (2,4,6-trimethylbenzoyl-diphenylphosphine oxide, manufactured by IGM Resins B.V., trade name "Omnirad TPO").

Example 4
A resin composition was prepared by mixing 100 parts by weight of ester compound B and 10 parts by weight of Omnirad TPO.

Example 5
100 parts by mass of ester compound A, 25 parts by mass of diphenylmethane diisocyanate (manufactured by Tosoh Corporation, trade name "Millionate MT"), and 13 parts by mass of Omnirad TPO were mixed, and then cured at 80°C for 24 hours to prepare a resin composition.

(Comparative Example 1)
Ester compound B was used as a resin composition without being mixed with other components.

(Comparative Example 2)
A resin composition was prepared by mixing 100 parts by mass of polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., trade name "PEG-2000", molecular weight 2000) and 10 parts by mass of Omnirad TPO.

The resin composition was irradiated with light from a high-pressure mercury lamp at an illuminance of 100 mW with an integrated light quantity of 2000 mJ/ ^cm2 . The viscosity of the resin composition before and after light irradiation was measured at 25°C or 60°C using an E-type viscometer (TV-22, manufactured by Toki Sangyo Co., Ltd.). The results are shown in Table 1.

Claims (5)

A method for synthesizing an ester compound, comprising : subjecting a dicarboxylic acid ester having a disulfide bond to a transesterification reaction with a polyol to obtain an ester compound having a disulfide bond in the molecular chain and a hydroxy group at a terminal thereof;
The method for synthesizing an ester compound, wherein the molar ratio of alkyl ester groups in the dicarboxylic acid ester is 0.5 to 0.9 moles per mole of hydroxy groups in the polyol . 2. The method for synthesizing an ester compound according to claim 1, wherein the transesterification reaction is carried out using a titanium compound as a catalyst. 3. The method for synthesizing an ester compound according to claim 1, wherein the ester compound has a hydroxyl value of 20 to 150 mgKOH/g. The method for synthesizing an ester compound according to any one of claims 1 to 3 , wherein the dicarboxylic acid ester comprises at least one selected from the group consisting of dimethyl 3,3'-dithiopropionate, dimethyl dithiodiacetate, and dimethyl 4,4'-dithiodibutyrate. The method for synthesizing an ester compound according to any one of claims 1 to 4 , wherein the polyol comprises at least one selected from the group consisting of polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, polybutadiene polyols, and bisphenol A-ethylene oxide addition diols.