JP2008231105A - Oligoester and ultraviolet-curing resin composition containing oligoester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet-curing resin composition that does not cause a problem such as productivity decline and environmental deterioration in use for paint or the like, especially an ultraviolet-curing resin composition suitable for the use for paint and the like that is free of organic solvents and good in workability. <P>SOLUTION: The present invention relates to an oligoester having an average molecular weight of 500 to 5,000 where all terminals are esterified and at least one of the terminals forms an ester with an oxetane compound having a hydroxyl group in the molecule. The oligoester is preferably an oligoester obtained by condensation polymerization of a polyvalent carboxylic acid and a polyhydric alcohol. The polyvalent carboxylic acid is preferably an aromatic dicarboxylic acid or a cycloaliphatic dicarboxylic acid, whereas the polyhydric alcohol is preferably an aliphatic diol or a cycloaliphatic diol. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a novel oligoester having an oxetane ring and an ultraviolet curable resin composition containing the oligoester. Since such an oligoester can be used as an ultraviolet curable resin composition, a flexible coating film can be formed on the surface of a substrate such as metal, plastic, concrete, and wood, and is useful as a paint.

The ultraviolet curable resin composition is excellent in workability and is used in many applications such as paint. However, since this composition usually contains an organic solvent for adjusting the viscosity, it is necessary to remove the organic solvent by a method such as heating after coating, which causes problems such as reduced productivity and environmental degradation. is doing.

The present invention is an ultraviolet curable resin composition that does not cause problems such as a decrease in productivity and environmental deterioration in applications such as paints, and in particular, for applications such as paints that do not contain an organic solvent and have good workability. It is an object to provide a suitable ultraviolet curable resin composition.

An object of the present invention is to provide an oligoester having an average molecular weight of 500 to 5000, which is esterified with an oxetane compound in which all terminals are esterified and at least one of which has a hydroxyl group, and the oligoester and photocationic polymerization. This is solved by an ultraviolet curable resin composition comprising an initiator.

According to the present invention, in an application such as a paint, an ultraviolet curable resin composition that does not cause problems such as a decrease in productivity and an environmental deterioration, in particular, an application such as a paint that does not contain an organic solvent and has good workability. A suitable ultraviolet curable resin composition can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

[Oligoester]
The ultraviolet curable resin composition of the present invention comprises an oligoester having an average molecular weight of 500 to 5,000, in which all terminals are esterified and at least one of them forms an ester with an oxetane compound having a hydroxyl group in the molecule. Comprising.
This oligoester is an oligoester obtained by polycondensation of a polycarboxylic acid and a polyhydric alcohol, especially an oligoester obtained by polycondensation of a dicarboxylic acid and a diol, especially an alicyclic dicarboxylic acid or an aromatic dicarboxylic acid An oligoester obtained by polycondensation of a diol with an aliphatic diol is preferred, and all ends (particularly both ends) are esterified, and at least one of them forms an ester with an oxetane compound having a hydroxyl group. The average molecular weight is 500 to 5000.

The polycarboxylic acid is preferably a dicarboxylic acid. Among them, alicyclic dicarboxylic acids having 8 to 20 carbon atoms such as aliphatic dicarboxylic acids having 4 to 20 carbon atoms such as succinic acid, adipic acid and sebacic acid, 1,4-cyclohexanedicarboxylic acid and 1,2-cyclohexanedicarboxylic acid. More preferred are aromatic dicarboxylic acids having 8 to 20 carbon atoms such as acid, terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid. Of these, alicyclic dicarboxylic acids and aromatic dicarboxylic acids are particularly preferred.

As the polyhydric alcohol, a diol is preferable, and an aliphatic diol is particularly preferable. The aliphatic diol may contain an ether bond, an unsaturated bond, an alicyclic structure, etc. in the carbon chain, such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, Carbon chain containing ether bonds such as 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,7-heptanediol, diethylene glycol, dipropylene glycol, triethylene glycol, etc. , 1,4-butenediol, those containing unsaturated bonds such as 2,5-dimethyl-3-hexene-2,5-diol in the carbon chain, fats such as 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc. Specific examples include those containing a cyclic structure in the carbon chain.

In order to obtain the oligoester, first, its precursor (all terminals are esterified but not forming an ester with an oxetane compound having a hydroxyl group, or all terminals are carboxyl terminals) To prepare. As the precursor, the former is preferable, and those having an average molecular weight of 400 to 5000 determined by NMR are preferable so that an oligoester having an average molecular weight of 500 to 5000 is obtained.

The precursor can be obtained, for example, by subjecting the polyvalent carboxylic acid ester (preferably dicarboxylic acid ester) and a polyhydric alcohol (preferably diol) to a condensation polymerization reaction. At this time, polyvalent carboxylic acid or polyvalent carboxylic acid anhydride can be used instead of polyvalent carboxylic acid ester, but polyvalent carboxylic acid ester is preferably used.

Preferred examples of the polyvalent carboxylic acid ester include alkyl esters of the polyvalent carboxylic acid (particularly dicarboxylic acid dialkyl esters). For example, dimethyl succinate, dimethyl adipate, dimethyl sebacate, etc., aliphatic dicarboxylic acid dialkyl esters having 1 to 4 carbon atoms, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 1,2-cyclohexanedicarboxylate Aromatic having an alkyl group having 1 to 4 carbon atoms such as alicyclic dicarboxylic acid dialkyl ester having 1 to 4 carbon atoms such as dimethyl terephthalate, dimethyl isophthalate, dimethyl 2,6-naphthalenedicarboxylate Preferred are dicarboxylic acid dialkyl esters such as group dicarboxylic acid dialkyl esters. The alkyl groups of the polyvalent carboxylic acid alkyl ester are preferably the same as each other.

In addition, preferred examples of the polyvalent carboxylic acid anhydride include dicarboxylic acid anhydrides such as succinic anhydride, 1,2-cyclohexanecarboxylic acid anhydride (hexahydrophthalic anhydride), and phthalic anhydride.

When dicarboxylic acid dialkyl ester and diol are subjected to a condensation polymerization reaction (transesterification reaction) to obtain a precursor of the above oligoester (both ends are esterified but not formed with an oxetane compound having a hydroxyl group). In order to obtain a precursor in which both ends are esterified, it is preferable to carry out the reaction while extracting by-produced alkyl alcohol at a ratio of diol: dicarboxylic acid dialkyl ester (molar ratio) = n: (n + 1). . The reaction formula in this case is shown by the following formula. In preparing the precursor, it is preferable to adjust the ratio of the raw materials so that the molecular weight is within the above range.

（式中、Ａはジカルボン酸ジアルキルエステルのエステル基を除いた部分、Ｂはジオールの水酸基を除いた部分、Ｒ1はアルキル基を示し、ｎは２〜３０の整数で平均重合度を示す。）

(In the formula, A is a portion excluding the ester group of the dicarboxylic acid dialkyl ester, B is a portion excluding the hydroxyl group of the diol, R 1 is an alkyl group, and n is an integer of 2 to 30 indicating the average degree of polymerization.)

In the above reaction, the catalyst may be an ordinary transesterification catalyst, and for example, tetra-n-butoxy titanium, tetraisopropoxy titanium, tetramethoxy titanium and the like can be used. The amount of catalyst used is preferably about 0.01 to 10 millimoles per mole of diol.

Moreover, it is preferable that the reaction temperature in this case is the range of 100-250 degreeC. The reaction pressure should just be the range which can extract the by-produced alkyl alcohol by distillation at the reaction temperature. That is, at the initial stage of the reaction, the alcohol is distilled at a normal pressure, and then the distillation decreases as the reaction proceeds. Accordingly, the alcohol can be distilled at a reduced pressure correspondingly. preferable. For example, the reaction may be started at normal pressure and after several hours, the pressure may be reduced to 50 to 300 mmHg and allowed to react for about 5 hours. After that, since the alcohol hardly distills, the degree of vacuum is finally increased as much as possible (reduced pressure to 1 to 5 mmHg) to remove unreacted substances and esterification of the terminal (about 2 hours). It is preferable to carry out. After the reaction, the target precursor can be obtained as a viscous liquid. The reaction is preferably carried out in an inert gas stream such as nitrogen or in an atmosphere throughout the entire process.

When a dicarboxylic acid or dicarboxylic acid anhydride and a diol are reacted to obtain the oligoester precursor (both ends are carboxyl-terminated), a precursor having both ends carboxyl-terminated is obtained. In addition, it is preferable to control the ratio of the diol with respect to the dicarboxylic acid or dicarboxylic acid anhydride as in the case of the precursor preparation. In this case, an ordinary acid catalyst may be used as the catalyst as required. Other reaction conditions are the same as described above.

Next, the target oligoester can be obtained by reacting the precursor thus obtained with an oxetane compound having a hydroxyl group in the molecule. The reaction formula in the case of using an oxetane compound having both ends esterified but having a hydroxyl group and a precursor not forming an ester is shown below.

（式中、Ａ、Ｂ、Ｒ¹、ｎは前記と同様で、Ｙは分子中に水酸基を有するオキセタン化合物の水酸基を除いた部分を示す。）

(In the formula, A, B, R ¹ and n are the same as described above, and Y represents a portion excluding the hydroxyl group of the oxetane compound having a hydroxyl group in the molecule)

In this case, in order to produce the target oligoester, the oxetane compound having a hydroxyl group is preferably used in an amount of 2 moles or more, more preferably about 3 to 10 moles per mole of precursor. As the catalyst, an ordinary transesterification catalyst can be used as in the preparation of the precursor. Reaction conditions such as the amount of catalyst used, reaction temperature, reaction pressure and reaction atmosphere are the same as in the case of the precursor preparation. After the reaction, the desired oligoester can be obtained as a viscous liquid.

In addition, when using the precursor derived from other polyhydric carboxylic acid, the oxetane compound which has a hydroxyl group is equimolar or more with respect to 1 mol of terminal ester groups or carboxyl groups of a precursor, Furthermore, 1.5-5 It is preferable to use about mole. The conditions in this case are the same as described above.

Preferred examples of the oxetane compound having a hydroxyl group in the molecule include 3-hydroxymethyloxetane compounds represented by the following formula.

（式中、Ｒ²は水素原子又は炭素数１〜６のアルキル基を表す。）

(In the formula, R ² represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.)

In the above formula, R ² is a hydrogen atom, an alkyl having 1 to 6 carbon atoms such as a methyl group, an ethyl group, an n- (or iso-) propyl group, or an n- (or iso-, sec-) butyl group. Among them, a hydrogen atom, a methyl group, and an ethyl group are preferable, and among them, a methyl group and an ethyl group are more preferable.

Examples of the 3-hydroxymethyl oxetane compound include 3-hydroxy-3-hydroxymethyl oxetane such as 3-hydroxymethyl oxetane, 3-methyl-3-hydroxymethyl oxetane, and 3-ethyl-3-hydroxymethyl oxetane. Among them, among them, 3-alkyl-3-hydroxymethyl oxetane (particularly 3-methyl-3-hydroxymethyl oxetane, 3-ethyl-3-hydroxymethyl oxetane) is preferable. The oxetane compound can be synthesized by, for example, a method in which a cyclic carbonate is produced from 1,1,1-trimethylolalkane and dialkyl carbonate and then decarboxylated (see J. Am. Chem. Soc., 1957, 79). ).

The target oligoester thus obtained is ester averaged at all ends, at least one of which forms an ester with an oxetane compound having a hydroxyl group in the molecule, and is determined by NMR. Those having a molecular weight of 500 to 5000, more preferably 600 to 2000 are preferred. In particular, an oligoester having a diester and a diol as a repeating unit, in which both ends are esterified and at least one of them forms an ester with an oxetane compound having a hydroxyl group in the molecule, among which both ends are molecules It preferably forms an ester with an oxetane compound having a hydroxyl group therein, and has an average molecular weight of 500 to 5000, more preferably 600 to 2000, determined by NMR.

(Photocationic polymerization initiator)
Preferred examples of the cationic photopolymerization initiator used in the present invention include compounds capable of generating cations by UV irradiation to initiate oxetane ring opening and cationic polymerization. As such a compound, an onium salt capable of releasing a Lewis acid represented by the following formula is preferable.

（式中、Ｑは、Ｓ、Ｓｅ、Ｔｅ、Ｐ、Ａｓ、Ｓｂ、Ｂｉ、Ｆｅ、Ｏ、Ｉ、Ｂｒ、Ｃｌ、又はＮ≡Ｎを表し、Ｒ³、Ｒ⁴、Ｒ⁵、Ｒ⁶は同一又は異なる有機基を表し、ａ、ｂ、ｃ、ｄは０〜３の整数を表し、ａ＋ｂ＋ｃ＋ｄはＭの価数に等しい。Ｍは上記式のアニオン部の中心原子を構成する金属又はメタロイドであり、例えば、Ｂ、Ｐ、Ａｓ、Ｓｂ、Ｆｅ、Ｓｎ、Ｂｉ、Ａｌ、Ｃａ、Ｉｎ、Ｔｌ、Ｚｎ、Ｓｃ、Ｖ、Ｃｒ、Ｍｎ、又はＣｏを表す。Ｘはハロゲン原子を表し、ｍはＭの原子価に等しい。なお、有機基としては、アリール基等が挙げられ、ハロゲン原子としては、Ｆ、Ｃｌ、Ｂｒ等が挙げられる。）

(Wherein Q represents S, Se, Te, P, As, Sb, Bi, Fe, O, I, Br, Cl, or N≡N, and R ³ , R ⁴ , R ⁵ , R ⁶ are The same or different organic groups are represented, a, b, c, d represent an integer of 0 to 3, and a + b + c + d is equal to the valence of M. M is a metal or metalloid constituting the central atom of the anion moiety of the above formula. Yes, for example, B, P, As, Sb, Fe, Sn, Bi, Al, Ca, In, Tl, Zn, Sc, V, Cr, Mn, or Co. X represents a halogen atom, m represents (It is equal to the valence of M. Examples of the organic group include an aryl group, and examples of the halogen atom include F, Cl, and Br.)

Examples of the cation (onium ion) in the above formula include diphenyliodonium ion, bis (4-methoxyphenyl) iodonium ion, bis (4-methylphenyl) iodonium ion, bis (4-t-butylphenyl) iodonium ion, bis Iodonium ions such as (dodecylphenyl) iodonium ion, triphenylsulfonium ion, diphenyl-4-thiophenoxyphenylsulfonium ion, bis [4- (diphenylsulfonio) phenyl] sulfide ion, bis [4- (di (4- (2-hydroxyethyl) phenyl) sulfonio) phenyl] sulfonium ions such as sulfide ions, and η ⁵ -2,4- (cyclopentadienyl) [(1,2,3,4,5,6-η)- (Methylethyl) benzene] -Iron (1+) ion etc. are mentioned.

Examples of the anion [MX _{m + k} ] ^−k in the above formula include tetrafluoroborate ion (BF ₄ ⁻ ), hexafluorophosphate ion (PF ₆ ⁻ ), hexafluoroantimonate ion (SbF ₆ ⁻ ), and hexafluoro. Examples include arsenate ions (AsF ₆ ⁻ ) and hexachloroantimonate ions (SbCl ₆ ⁻ ).

Further, perchlorate ion (ClO ₄ ⁻ ), trifluoromethanesulfonate ion (CF ₃ SO ₃ ⁻ ), fluorosulfonate ion (FSO ₃ ⁻ ), toluenesulfonate ion (CH ₃ C ₆ H ₅ SO ₃ ⁻ ) , Trinitrobenzenesulfonate ion, trinitrotoluenesulfonate ion and the like.

Furthermore, aromatic onium salts can also be used as the photocationic polymerization initiator of the present invention. For example, aromatic halonium salts (see JP 50-151996, JP 50-158680, etc.), VIA aromatic onium salts (JP 50-151997, JP 52-30899). No. 5, JP-A 56-55420, JP-A 55-125105, etc.), VA group aromatic onium salts (see JP 50-158698 A, etc.), oxosulfoxonium salts (special JP-A-56-149402, JP-A-57-192429, etc.), aromatic diazonium salts (see JP-A-49-17040, etc.), thiopyrylium salts (US Pat. No. 4,139,655) and the like. Can be mentioned. Moreover, an iron / allene complex, an aluminum complex / photolytic silicon compound-based initiator, and the like can also be mentioned as the photocationic polymerization initiator of the present invention.

As a commercially available product of the photocationic polymerization initiator, for example, Cyracure UVI-6974 (a mixture of bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate and diphenyl-4-thiophenoxyphenylsulfonium hexafluoroantimonate) ), Cyracure UVI-6990 (hexafluorophosphate of UVI-6974) (manufactured by Union Carbide), Adekaoptomer SP-151, Adekaoptomer SP-170 (Bis [4- (Di (4- (2- (2- Hydroxyethyl) phenyl) sulfonio) phenyl] sulfide), Adeka optomer SP-150 (hexafluorophosphate of SP-170), Adeka optomer SP-171 (manufactured by Asahi Denka),

DTS-102, DTS-103, NAT-103, NDS-103 ((4-hydroxynaphthyl) -dimethylsulfonium hexafluoroantimonate), TPS-102 (triphenylsulfonium hexafluorophosphate), TPS-103 (triphenylphosphonium) Hexafluoroantimonate), MDS-103 (4-methoxyphenyl-diphenylsulfonium hexafluoroantimonate), MPI-103 (4-methoxyphenyliodonium hexafluoroantimonate), BBI-101 (bis (4-t-butylphenyl) ) Iodonium tetrafluoroborate), BBI-102 (bis (4-t-butylphenyl) iodonium hexafluorophosphate), BBI-103 (bis (4-t-butyl) Eniru) iodonium hexafluoroantimonate) (manufactured by Midori Chemical) and,

Irgacure 261 (η ⁵ -2,4-cyclopentadien-1-yl) [(1,2,3,4,5,6-η)-(1-methylethyl) benzene] -iron (1+) hexafluorophosphate ( 1-)) (manufactured by Ciba Geigy), CD-1010, CD-1011, CD-1012 (4- (2-hydroxytetradecanyloxy) diphenyliodonium hexafluoroantimonate) (above, manufactured by Sartomer),

CI-2481, CI-2624, CI-2638, CI-2064 (manufactured by Nippon Soda), Dekacur K126 (bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate) (manufactured by Degussa), RHODORSIL PHOTOINITIATOR 2074 ((Tricumyl) iodonium tetrakis (pentafluorophenyl) borate) (manufactured by Rhodia) can be used.

Among these, UVI-6974, UVI-6990, Adekaoptomer SP-170, Adekaoptomer SP-171, CD-1013, and MPI-103 can be preferably used.

[Ultraviolet curable resin composition]
The ultraviolet curable resin composition of the present invention comprises the oligoester and a photocationic polymerization initiator. In this composition, the cationic photopolymerization initiator is preferably contained in an amount of 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the oligoester. Moreover, it is preferable that the ultraviolet curable resin composition of this invention further contains the bisoxetane compound. The content is preferably 200 parts by weight or less, and more preferably about 50 to 100 parts by weight with respect to 100 parts by weight of the oligoester.

Examples of the bisoxetane compound include bis (3-ethyl-3-oxetanylmethyl) ether, 1,2-bis (3-ethyl-3-oxetanylmethoxy) ethane, and 1,4-bis (3-ethyl-3- Oxetanylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, 1,4-bis (3-ethyl-3-oxetanylmethoxy) -2-butene, 1,4-bis [(3 -Ethyl-3-oxetanylmethoxy) methyl] benzene, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] biphenyl and the like oxetane compounds (particularly 3-alkyl-3-oxetane compounds) ) Is preferred.

The ultraviolet curable resin composition of the present invention (particularly, a composition containing an oligoester and a photocationic polymerization initiator and further containing a bisoxetane compound) is cured with ultraviolet rays so that wood, metal, plastic, concrete, etc. A flexible coating film (cured product) can be formed on the surface of the substrate, and can be suitably used as a paint or the like. This ultraviolet curing is performed, for example, by applying an ultraviolet curable resin composition to the surface of the substrate, and then irradiating ultraviolet rays to open the oxetane ring of the oligoester and the bisoxetane compound and perform cationic polymerization.

It is preferable that the ultraviolet irradiation is performed at a wavelength of about 200 to 400 nm and an irradiation amount of about 10 to 3000 mJ / cm <2>, more preferably about 50 to 1000 mJ / cm <2>. For example, a 120 W / cm ultraviolet lamp may be used and irradiated with an irradiation distance of 11 cm and a feed rate of 0.7 to 3.5 m / min. In addition, the temperature at this time is not particularly limited as long as it does not hinder the formation of the coating film, and may usually be room temperature.

Examples of the ultraviolet light source include a mercury arc lamp, a xenon arc lamp, a fluorescent lamp, a carbon arc lamp, a tungsten-halogen copying lamp, a sodium lamp, and an alkali metal lamp. These light sources preferably have a tube that transmits light having a wavelength of about 185 to 400 nm, more preferably about 240 to 400 nm, but may have a tube made of quartz or Pyrex. .

Next, the present invention will be specifically described with reference to examples and comparative examples. In addition, ultraviolet irradiation and evaluation of hardened | cured material (coating film) were performed by the following method.

(1) UV irradiation Ushio Electric Unicure System UVC-1212 type UV irradiation device (output 1.5kw, metal halide lamp input 120W / cm, with cold filter), irradiation distance 11cm, conveyor speed 0.7mm / Irradiated with ultraviolet rays for min. In addition, when there was a tack (stickiness) by touching the surface of the sample after irradiation, the sample was irradiated again until no tack was recognized.

(2) About the sample from which the pencil hardness tack of a coating film was no longer recognized, the degree of damage was evaluated by the pencil hardness test based on JIS-K5400.

Example 1
Dimethyl 1,4-cyclohexanedicarboxylate (80.10 g / 0.4 mol; manufactured by Tokyo Chemical Industry; abbreviated as CHDC) is placed in a reaction vessel having an internal volume of 500 ml equipped with a thermometer, a stirrer, a cooling pipe, and a nitrogen gas introduction pipe. , Diethylene glycol (21.22 g / 0.2 mol; manufactured by Wako Pure Chemical; abbreviated as DEG), tetra-n-butoxy titanium (0.07 g / 0.02 mmol; manufactured by Wako Pure Chemical; abbreviated as TBT), It heated in the oil bath of 170 degreeC, introduce | transducing nitrogen gas under a normal pressure.

When the temperature in the reaction vessel reached 150 ° C., methanol started to distill, and after 5 hours from the start of the reaction, the distillation of methanol almost stopped. Therefore, the reaction was continued for 3 hours after reducing the pressure to 200 mmHg and then for another 2 hours after reducing the pressure to 50 mmHg. During this time, methanol distills slightly. And the pressure reduction degree was raised to 1-5 mmHg, and the unreacted raw material was distilled over 3 hours, and terminal esterification was performed. The obtained oligoester precursor (88.5 g) was a viscous liquid, and the average molecular weight determined by NMR measurement was 460.

To this oligoester precursor (40.0 g / 0.087 mol), 3-ethyl-3-hydroxymethyloxetane (40.40 g / 0.348 mol; manufactured by Ube Industries; abbreviated as EHO), TBT (0.012 g) /0.035 mmol) was added and heated in an oil bath at 170 ° C. while introducing nitrogen gas under normal pressure.

When the temperature in the reaction vessel reached 150 ° C., methanol started to distill, and after 4 hours from the start of the reaction, the distillation of methanol almost stopped. Therefore, the pressure was reduced to 200 mmHg for 5 hours, and then the pressure was reduced to 50 mmHg and the reaction was continued for another 2 hours. During this time, methanol distills slightly. And the pressure reduction degree was raised to 1-5 mmHg, while unreacted raw material was distilled over 3 hours, and terminal esterification (ester formation with EHO) was performed. The obtained oligoester (57.6 g) was a viscous liquid, the average molecular weight determined by NMR measurement was 600, and the viscosity was 3500 poise.

This oligoester (10 g) was mixed with bis (3-ethyl-3-oxetanylmethyl) ether (5 g; manufactured by Ube Industries; abbreviated as DOE) to adjust the viscosity to 1000 poise, and then UVI as a photocationic polymerization initiator. -6990 (0.6 g; manufactured by Union Carbide) was blended to prepare an ultraviolet curable resin composition. This ultraviolet curable resin composition was applied to a slide glass to a thickness of about 100 microns, and ultraviolet irradiation and a cured product (coating film) were evaluated as described above. The composition, physical properties and the like are shown in Table 1, and the evaluation results are shown in Table 2.

Example 2
In the same reaction vessel as in Example 1, dimethyl terephthalate (41.97 g / 0.216 mol; manufactured by Tokyo Chemical Industry; abbreviated as TPDM), DEG (16.22 g / 0.153 mol), 1,4-butenediol (3.37 g / 0.038 mol; manufactured by Wako Pure Chemical Industries, Ltd .; abbreviated as BED) and TBT (0.034 g / 0.10 mmol) were charged and reacted in the same manner as in Example 1. The obtained oligoester precursor (47.6 g) was a very viscous liquid, and the average molecular weight determined by NMR measurement was 1960.

To this oligoester precursor (37.3 g / 0.0191 mol), EHO (8.85 g / 0.0762 mol) and TBT (0.013 g / 0.038 mmol) were added. Reaction was performed. The obtained oligoester (42.4 g) was a very viscous liquid, and the average molecular weight determined by NMR measurement was 1800.

After blending DOE (10 g) with this oligoester (10 g) and adjusting the viscosity to 1300 poise, UVI-6990 (0.8 g) was blended to prepare an ultraviolet curable resin composition. Similarly, ultraviolet irradiation and evaluation of a cured product (coating film) were performed. The composition, physical properties and the like are shown in Table 1, and the evaluation results are shown in Table 2.

Example 3
In the same reaction vessel as in Example 1, dimethyl isophthalate (43.34 g / 0.223 mol; manufactured by Tokyo Chemical Industry; abbreviated as IPDM), DEG (14.70 g / 0.139 mol), BED (3.05 g / 0.035 mol) and TBT (0.029 g / 0.09 mmol) were charged, and the reaction was carried out in the same manner as in Example 1. The obtained oligoester precursor (49.6 g) was a very viscous liquid, and the average molecular weight determined from NMR measurement was 880.

To this oligoester precursor (47.3 g / 0.0534 mol), EHO (24.89 g / 0.214 mol) and TBT (0.013 g / 0.038 mmol) were added. Reaction was performed. The obtained oligoester (62.3 g) was a very viscous liquid, the average molecular weight determined by NMR measurement was 930, and the viscosity was 95,000 poise.

After blending DOE (10 g) with this oligoester (10 g) and adjusting the viscosity to 1000 poise, UVI-6990 (0.8 g) was blended to prepare an ultraviolet curable resin composition. Similarly, ultraviolet irradiation and evaluation of a cured product (coating film) were performed. The composition, physical properties and the like are shown in Table 1, and the evaluation results are shown in Table 2.

Example 4
In a reaction vessel similar to Example 1, IPDM (85.54 g / 0.425 mol), DEG (14.47 g / 0.138 mol), BED (5.99 g / 0.065 mol), cyclohexanedimethanol ( 19.60 g / 0.136 mol; manufactured by Eastman Chemical; abbreviated as CHDM) and TBT (0.058 g / 0.174 mmol) were charged and reacted in the same manner as in Example 1. The oligoester precursor (103.5 g) obtained after the reaction was a liquid with almost no fluidity, and the average molecular weight determined by NMR measurement was 990.

To this oligoester precursor (92.0 g / 0.093 mol), EHO (44.84 g / 0.386 mol) and TBT (0.092 g / 0.27 mmol) were added. Reaction was performed. The obtained oligoester (112.9 g) was a liquid with almost no fluidity, and the average molecular weight determined by NMR measurement was 1000.

After blending DOE (10 g) with this oligoester (10 g) and adjusting the viscosity to 1100 poise, UVI-6990 (0.8 g) was blended to prepare an ultraviolet curable resin composition. Similarly, ultraviolet irradiation and evaluation of a cured product (coating film) were performed. The composition, physical properties and the like are shown in Table 1, and the evaluation results are shown in Table 2.

Comparative Example 1
A reaction vessel similar to that in Example 1 was charged with CHDC (41.67 g / 0.4 mol), DEG (21.22 g / 0.2 mol), and TBT (0.007 g / 0.02 mmol). The reaction was carried out in the same manner as in Example 1. The oligoester precursor (50.3 g) obtained after the reaction was almost solid, and the average molecular weight determined by NMR measurement was 5400.

To this oligoester precursor (40.0 g / 0.00733 mol), EHO (4.40 g / 0.0293 mol) and TBT (0.001 g / 0.0029 mmol) were added. Reaction was performed. The obtained oligoester (41.7 g) was almost solid, and the average molecular weight determined by NMR measurement was 5,500.

DOE (10 g) was blended with this oligoester (10 g) and attempted to be dissolved by heating. However, an undissolved portion remained and the oligoester precipitated after cooling. For this reason, it was not possible to uniformly apply to the slide glass, and it was impossible to evaluate the ultraviolet irradiation and the cured product (coating film). The composition, physical properties and the like are shown in Table 1, and the evaluation results are shown in Table 2.

Comparative Example 2
In the same reaction vessel as in Example 1, dimethyl adipate (56.88 g / 0.4 mol; manufactured by Tokyo Chemical Industry; abbreviated as ADM), DEG (21.22 g / 0.2 mol), TBT (0.007 g / 0.02 mmol) was charged, and the reaction was carried out in the same manner as in Example 1. The oligoester precursor (65.3 g) obtained after the reaction was a viscous liquid, and the average molecular weight determined by NMR measurement was 360.

To this oligoester precursor (40.0 g / 0.111 mol), EHO (25.81 g / 0.222 mol) and TBT (0.008 g / 0.022 mmol) were added. Reaction was performed. The obtained oligoester (58.2 g) was a viscous liquid, the average molecular weight determined by NMR measurement was 490, and the viscosity was 2100 poise.

After blending DOE (5 g) with this oligoester (10 g) and adjusting the viscosity to 800 poise, UVI-6990 (0.6 g) was blended to prepare an ultraviolet curable resin composition. Similarly, ultraviolet irradiation and evaluation of a cured product (coating film) were performed. The composition, physical properties and the like are shown in Table 1, and the evaluation results are shown in Table 2.

Claims (7)

An oligoester having an average molecular weight of 500 to 5,000, in which all terminals are esterified and at least one of them forms an ester with an oxetane compound having a hydroxyl group in the molecule. The oligoester according to claim 1, wherein the oligoester is an oligoester obtained by condensation polymerization of a polyvalent carboxylic acid and a polyhydric alcohol. The oligoester according to claim 2, wherein the polyvalent carboxylic acid is an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, and the polyhydric alcohol is an aliphatic diol or an alicyclic diol. The oligoester according to claim 1, wherein the oxetane compound having a hydroxyl group is a 3-hydroxymethyloxetane compound. An ultraviolet curable resin composition comprising the oligoester according to claim 1 and a cationic photopolymerization initiator. The ultraviolet curable resin composition according to claim 5, further comprising a bisoxetane compound. A paint comprising the ultraviolet curable resin composition according to claim 5 or 6.