JP2007269969A - Photocurable resin composition - Google Patents

Abstract

The present invention provides a photocurable resin composition that is not subject to polymerization inhibition by oxygen during curing in the atmosphere and that can impart both scratch resistance and flexibility to a cured product.
A photocurable resin composition comprising a compound (A) having at least two thiol groups in the molecule and a compound (B) having at least two methacryloyl groups in the molecule, and (A ) Thiol group and (B) methacryloyl group have a functional group equivalent ratio of (A) / (B) = 5/95 to 45/55.
[Selection figure] None

Description

  The present invention relates to a photocurable resin composition, particularly a thiol / ene-based photocurable resin composition, and relates to a resin composition having flexibility while the obtained cured product has sufficient scratch resistance.

Photocuring in which a resin composition is cured using an active energy ray such as ultraviolet rays is an excellent technique that saves energy as compared with conventional thermosetting, has no solvent, and has a low environmental impact. As a photocurable resin composition used in this technique, a radically polymerizable one containing a compound having a methacryloyl group as a component is known.
However, radical polymerizable photocuring of a compound having a methacryloyl group is susceptible to curing inhibition by oxygen, and it is difficult to obtain a film-like cured product due to the influence of residual oxygen even under deaeration (for example, Non-Patent Document 1).
For the problem of curing inhibition by oxygen, (1) increase the amount of photopolymerization initiator added, (2) increase the amount of irradiation energy, or (3) change to a photocuring system that does not suffer from curing inhibition by oxygen, etc. A method can be considered.
However, the methods (1) and (2) are not preferable from the viewpoints of energy efficiency and cost.
On the other hand, as one of the above methods (3), the change to the photo-curing system by polythiol having a plurality of thiol groups and polyene having a plurality of carbon-carbon double bonds should not be inhibited by oxygen. Is known, and a film-like cured product can be obtained even in the atmosphere. However, it has been difficult to achieve both flexibility and scratch resistance in the obtained cured product.

For example, Patent Document 1 discloses a polyvalent thiol that is excellent in storage stability of a composition, has high productivity, has excellent adhesive properties such as holding power, and is suitable for the field of production and use of pressure-sensitive adhesives and pressure-sensitive adhesive sheets. An active energy ray-curable composition containing a compound and a polyvalent ene compound has been proposed.
As a specific example, Patent Document 1 discloses photocuring using p-diallyl phthalate and butanediol bisthiopropionate, but the obtained cured product cannot obtain sufficient scratch resistance.

Further, Patent Document 2 proposes a photocurable resin composition that contains polyene and polythiol as main components, has a high refractive index, and can adjust the refractive index with high accuracy.
In Patent Document 2, as a specific example, triallyl triisocyanurate as a polyene, trimethylolpropane-tris- (β-thiopropionate) as a polythiol, and a compound having a bromine-substituted aromatic ring as tetrabromo Although photocuring is performed using bisphenol A, the obtained cured product is hard and sufficient flexibility cannot be obtained.

Further, Patent Document 3, as the light transmittance and the cured resin is that composition obtained is excellent in water resistance, a compound having a skeleton containing groups such as norbornene 2 or more, a compound having two or more thiol groups Compositions that contain no photoradical generator have been proposed.
In Patent Document 3, as a specific example, thermosetting is performed using dinorbornene carboxylate of dicyclopentadiene dimethanol and pentaerythritol tetra (3-mercaptopropionate). However, the obtained cured product is hard and sufficient flexibility cannot be obtained.

Kato Kiyomi, "UV Curing System", pages 43-61, 221-259, 337-449 (1989) JP 2004-35734 A JP 2003-277505 A JP 2003-20334 A

  It is an object of the present invention to provide a photocurable resin composition that is not subjected to polymerization inhibition by oxygen during curing in the atmosphere, and can further impart both scratch resistance and flexibility to a cured product. Objective.

  As a result of intensive studies to solve the above problems, the present inventors have found that a photocurable resin composition containing a specific polythiol and a specific polyene compound at a predetermined ratio is oxygenated during curing in the atmosphere. The present inventors have found that the cured product is characterized by having both scratch resistance and flexibility without being inhibited by polymerization.

That is, the present invention
(1) A photocurable resin composition comprising a compound (A) having two or more thiol groups in the molecule and a compound (B) having two or more methacryloyl groups in the molecule, and the compound (A) A photocurable resin composition in which the functional group equivalent ratio of the thiol group to the methacryloyl group of the compound (B) is (A) / (B) = 5/95 to 45/55,
(2) The photocurable resin composition according to (1), wherein the compound (A) is a compound represented by the general formula (I),

〔式中、Ｚ¹は２〜６の価数を有する有機残基であり、ｎは２〜６の整数であり、かつＺ¹の価数を超えることはない。Ｘは、−Ｏ−ＣＯ−、−Ｏ−または−ＨＮ−ＣＯ−の何れかを表し、Ｙは炭素数２〜８のアルキレン基または炭素数６〜２０のアリーレン基であり、ｖは０または１の整数である。〕

Wherein, Z ¹ is an organic residue having a valence of 2 to 6, n is an integer from 2 to 6, and does not exceed the valence of Z ^1. X represents -O-CO-, -O- or -HN-CO-, Y is an alkylene group having 2 to 8 carbon atoms or an arylene group having 6 to 20 carbon atoms, and v is 0 or It is an integer of 1. ]

(3) The photocurable resin composition according to (1) or (2), wherein the compound (B) is a compound represented by the general formula (II),

(式中、Ｚ²は２〜６価のアルコール残基であり、ｍは２〜６の整数であり、かつＺ²の価数を超えることはない。)

(In the formula, Z ² is a 2-6 valent alcohol residue, m is an integer of 2-6, and does not exceed the valence of Z ^2. )

(4) The above (1) containing 0.0001 to 1 part by mass of the nitrone compound (C) represented by the general formula (III) with respect to a total of 100 parts by mass of the compound (A) and the compound (B). -The photocurable resin composition in any one of (3),

(式中、Ｒ¹及びＲ²は、それぞれｔ-ブチル基、フェニル基またはナフチル基のいずれかを表す。)

(In the formula, R ¹ and R ² each represent a t-butyl group, a phenyl group, or a naphthyl group.)

(5) Further, the compound (D) having a nitroxide group represented by the general formula (IV) is contained in an amount of 0.0001 to 1 part by mass with respect to 100 parts by mass in total of the compound (A) and the compound (B). (1)-the photocurable resin composition in any one of (4), and

(式中、Ｒ³は、ＯＨ、ＣＯＯＨまたはＨの何れかを表す。)

(In the formula, R ³ represents OH, COOH or H.)

(6) Further, the compound (E) having a nitroso group represented by the general formula (V) is contained in an amount of 0.0001 to 1 part by mass with respect to 100 parts by mass in total of the compound (A) and the compound (B). The photocurable resin composition according to any one of (1) to (4) R ⁴ —NO (V)
(In the formula, R ⁴ represents an alkyl group or an aryl group.)
Is to provide.

The photo-curable resin composition of the present invention can be photo-cured in the atmosphere without being hindered by polymerization due to oxygen. Therefore, it is necessary to blow an inert gas to remove oxygen or to work in a vacuum. do not need. Therefore, it has become possible to perform photocuring regardless of the presence or absence of an inert gas supply facility or a vacuum facility. In addition, both the scratch resistance and flexibility can be imparted to the resulting cured product. Moreover, the photocurable resin composition which has storage stability can be provided.
Moreover, since the photocurable resin composition of the present invention can be stored for a longer period of time by adding a storage stabilizer, it is excellent in handling properties.

Hereinafter, the present invention will be described in more detail.
The photocurable resin composition of the present invention has a compound (A) having two or more thiol groups in the molecule [hereinafter sometimes simply referred to as a compound (A). And a compound (B) having two or more methacryloyl groups in the molecule [hereinafter sometimes referred to simply as a compound (B). And a functional group equivalent ratio of the thiol group of the compound (A) and the methacryloyl group of the compound (B) is (A) / (B) = 5/95 to 45/55 It is characterized by being.

  The compound (A) having two or more thiol groups in the molecule used in the present invention is represented by the following general formula (I).

In the formula (I), Z ¹ is an organic residue having a valence of 2 to 6, n is an integer from 2 to 6, and does not exceed the valence of Z ^1. X represents any of ester (—O—CO—), ether (—O—) or amide (—HN—CO—), Y represents an alkylene group having 2 to 8 carbon atoms, or 6 to 20 carbon atoms. And v is an integer of 0 or 1. When v is 0, for example, ethanedithiol, propanedithiol, butane-1,4-dithiol, hexamethylenedithiol, decamethylenedithiol, tolylene-2,4-dithiol, 1,4-phenylenedithiol, xylylenedithiol, etc. Is mentioned. Examples of those in which v is 1 and X is an ester (—O—CO—) include, for example, trimethylolpropane-tris- (3-mercaptopropionate), pentaerythritol-tetrakis- (3-mercaptopropionate), etc. Examples of ether (—O—) include 3,6-dioxaoctane-1,8-dithiol, and examples of amide (—HN—CO—) include 1, 3,5-tris (3-mercaptopropyl) isocyanurate is mentioned.
Moreover, these can be used as a 1 type, or 2 or more types of mixture. Further, from the viewpoint of flexibility, Z ¹ in formula (I) is preferably 3 to 6 valences, and more preferably 3 to 4 valences from the viewpoint of availability.

  Examples of the compound (B) having two or more methacryloyl groups in the molecule used in the present invention may include methacrylic acid esters of divalent to hexavalent alcohols represented by the following general formula (II).

In formula (II), Z ² is a group given by removing hydroxyl groups from divalent to hexavalent alcohol, m is an integer from 2 to 6, and does not exceed the valence of Z ^2.
Examples of the divalent to hexavalent alcohol include ethylene glycol, diethylene glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol. From the viewpoint of flexibility, a divalent or trivalent alcohol is more preferable. Moreover, these can be used as a 1 type, or 2 or more types of mixture. Further, from the viewpoint of flexibility, Z ^{2 in the} formula (II) preferably has a polyalkylene glycol chain.
Although it does not specifically limit as a compound (B) which has 2 or more of methacryloyl groups in 1 molecule used for this invention, For example, 1, 4- butanediol dimethacrylate, 1, 6-hexanediol Dimethacrylate, diethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, bisphenol A diethoxydimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetra Methacrylate, dipentaerythritol hexamethacrylate, trismethacryloxyethyl isocyanurate, etc. It is. These may be used alone or in combination of two or more.

The functional group equivalent ratio of the thiol group of compound (A) to the methacryloyl group of compound (B) is (A) / (B) = 5/95 to 45/55, and further (A) / (B) = 20/80. It is preferable that it is -45/55.
If the functional group equivalent ratio of the thiol group of the compound (A) and the methacryloyl group of the compound (B) is in the range of (A) / (B) = 5/95 to 45/55, the surface is hard and sufficient scratch resistance The photocurable resin composition which can obtain the hardened | cured material provided with flexibility can be provided.

  Furthermore, the photocurable resin composition of the present invention may be referred to as a nitrone compound (C) [hereinafter simply referred to as compound (C). ] Can be improved by adding 0.0001 to 1 part by mass with respect to 100 parts by mass in total of (A) and (B). The nitrone compound (C) is represented by the following general formula (III).

In the formula (III), R ¹ and R ² each represent a t-butyl group, a phenyl group or a naphthyl group. Examples of the nitrone compound include α-phenyl-Nt-butyl nitrone and α-naphthyl-Nt-butyl nitrone.
Further, Nt-butyl-α- (4-pyridyl-1-oxide) nitrone can be used as another compound. Moreover, these can be used as a 1 type, or 2 or more types of mixture.

  Furthermore, the photocurable resin composition of the present invention may be referred to as a nitroxide compound (D) [hereinafter simply referred to as compound (D). ] Can be improved by adding 0.0001 to 1 part by mass with respect to 100 parts by mass in total of (A) and (B). Examples of the compound (D) having a nitroxide group include compounds represented by the following general formula (IV).

In the formula (IV), R ³ represents OH, COOH or H.
For example, 2,2,6,6-tetramethyl-1-piperidinoxide (which is generally marketed under the name TEMPO), 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinoxide and the like can be mentioned. It is done.
Examples of other compounds include 2,2,2,5-tetramethyl-1-pyrrolidinyloxy (PROXYL), Nt-butyl-1-phenyl-2-methylpropyl nitroxide, Nt-butyl-1 -(2-naphthyl) -2-methylpropyl nitroxide, Nt-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide, Nt-butyl-1-dibenzylphosphono-2,2- Dimethylpropyl nitroxide, N-phenyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide, N-phenyl-1-diethylphosphono-1-methylethyl nitroxide, N- (1-phenyl-2-methylpropyl) -1-diethylphosphono-1-methylethyl nitroxide or the like can be used. Moreover, these can be used as a 1 type, or 2 or more types of mixture. Among these, it is preferable to use a compound represented by the general formula (IV), particularly TEMPO. Furthermore, storage stability can be further improved by using together with the said compound (C).

In addition, the photocurable resin composition of the present invention may be further referred to as a nitroso compound (E) [hereinafter simply referred to as compound (E). ] Can be increased by adding 0.0001 to 1 part by mass with respect to a total of 100 parts by mass of the compound (A) and the compound (B). Examples of the compound (E) having a nitroso group include compounds represented by the following general formula (V).
R ⁴ -NO (V)

In the formula (V), R ⁴ represents an alkyl group or an aryl group.
Examples of the compound (E) include nitrosobenzene, 2-nitrosotoluene, 1-nitroso-2-naphthol, N-nitrosophenyl hydroxylamine ammonium salt, 2-methyl-2-nitrosopropane dimer, N, N- Diethyl-N-nitrosoaniline, 4-nitrosodiphenylamine, 2-nitroso-1-naphthol, 5-nitroso-8-quinolinol, 5-methoxy-2-nitrosophenol, 1,3,5-tri-t-butyl-2 -Nitrosobenzene and the like. Moreover, these can be used as a 1 type, or 2 or more types of mixture. Furthermore, storage stability can be further improved by using together with the said compound (C).

The photocurable resin composition of the present invention is cured by irradiation with active energy rays such as ultraviolet rays, and a low pressure xenon lamp, a high pressure xenon lamp, a metal halide lamp, or the like can be used as a light source.
When the resin composition of the present invention is cured by irradiation with active energy rays such as ultraviolet rays, a photopolymerization initiator can be used. The photopolymerization initiator is a compound that generates radicals by active energy rays such as ultraviolet rays and visible light and promotes photocuring of the photocurable resin composition, and various known photopolymerization initiators are used. Is possible. Specifically, 1-hydroxycyclohexyl phenyl ketone, benzophenone, p-methoxybenzophenone, acetophenone, propiophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1 -One, 2,2-diethoxy-2-phenylacetophenone, benzoin methyl ether, benzoin ethyl ether, p-chlorobenzophenone, 4-benzoyl-4-methyldiphenyl sulfide, 2-benzyl-2-dimethylamino-1- (4 -Morpholinophenyl) -butanone-1, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropanone-1, and the like.
Moreover, these can be used as a 1 type, or 2 or more types of mixture. Content of a photoinitiator is about 0-10 mass parts normally with respect to a total of 100 mass parts of a compound (A) and (B), Preferably it is 0.5-5 mass parts.

  In addition, the photocurable resin composition of the present invention includes, as necessary, adhesion improvers such as silane coupling agents and acidic phosphate esters, antioxidants, curing accelerators, dyes, fillers, pigments, Additives such as thixotropic agents, plasticizers, surfactants, lubricants and antistatic agents can be added.

  The composition of the present invention is cured by irradiation with active energy rays such as ultraviolet rays, and the cured product has scratch resistance and flexibility, so that it is prominent in optical component filters and electronic component coatings. Show the effect.

EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to a following example at all.
In the following Examples and Comparative Examples, the compound (A) having at least two thiol groups in the molecule is referred to as a thiol compound, and the compound (B) having at least two methacryloyl groups in the molecule is referred to as an ene compound. Sometimes.

Example 1
As a thiol compound, pentaerythritol-tetrakis (3-mercaptopropionate) and diethylene glycol dimethacrylate as an ene compound are mixed so that the functional group equivalent ratio of the thiol group and the methacryloyl group is 20/80. 1 part by mass of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator was mixed in the part to prepare a photocurable resin composition.
This photocurable resin composition was applied onto a glass plate, and a glass plate was placed on the glass plate and sandwiched between them. The ultraviolet ray was irradiated at 1200 mJ / cm ² to obtain a film-like cured product having a thickness of 100 μm.

Example 2
A cured product was obtained in the same manner as in Example 1 except that the functional group equivalent ratio of thiol group and methacryloyl group was changed to 30/70.

Example 3
A cured product was obtained in the same manner as in Example 1 except that the functional group equivalent ratio of thiol group and methacryloyl group was changed to 40/60.

Example 4
Cured product as in Example 1, except that 1,4-butanediol-bis (3-mercaptobutyrate) was used as the thiol compound and the functional group equivalent ratio of the thiol group to the methacryloyl group was changed to 30/70. Got.

Example 5
A cured product was obtained in the same manner as in Example 1 except that polyethylene oxide (6 mol) -modified bisphenol A dimethacrylate was used as the ene compound and the functional group equivalent ratio of the thiol group to the methacryloyl group was changed to 40/60.

Comparative Example 1
A cured product was obtained in the same manner as in Example 1 except that the functional group equivalent ratio of thiol group and methacryloyl group was changed to 50/50.

Comparative Example 2
1 part by mass of 1-hydroxycyclohexyl phenyl ketone was mixed with 100 parts by mass of diethylene glycol dimethacrylate. In the same manner as in Example 1, ultraviolet rays were irradiated at 1200 mJ / cm ² to obtain a cured product.

About the hardened | cured material obtained in the said Examples 1-5 and Comparative Examples 1 and 2, the following physical-property evaluation was performed.
(1) Scratch hardness Scratch hardness (pencil method) was measured according to JIS K-5600-5-4.
(2) Storage elastic modulus Dynamic viscoelasticity tester (manufactured by SII NanoTechnology Inc .: obtained by performing a dynamic scan using a DMS series under the conditions of a heating rate of 2 ° C./min and a measurement frequency of 1 Hz. The storage elastic modulus (MPa) at a temperature of 150 ° C. of the cured film was measured.
In the evaluation of the present invention, the scratch hardness of 2B or more and the storage elastic modulus of 1000 MPa or less were used as a standard for achieving both scratch resistance and flexibility. The results are shown in Table 1.

From Table 1, the cured product of each example has a scratch hardness of 2B to 3H and a storage elastic modulus of 23 to 330 MPa, and has both scratch resistance and flexibility, while (A) / In Comparative Example 1 where the functional group equivalent ratio of (B) is 50/50, the scratch hardness is too soft as 4B, and in Comparative Example 2 where the functional group equivalent ratio is 0/100, the scratch hardness is 4H and the storage elastic modulus. Is 1500 MPa and lacks flexibility.

Example 6
45 parts by mass of pentaerythritol tetrakis (3-mercaptopropionate), 55 parts by mass of diethylene glycol dimethacrylate, and 1 part by mass of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator were mixed to obtain a photocurable resin composition. A sample to which α-phenyl-Nt-butylnitrone was not added and a sample to which 0.1% by mass and 0.5% by mass were added were obtained as the nitrone compound (C) with respect to the photocurable resin composition. .

Example 7
As a compound (D) having a nitroxide group, 100 parts by mass of 45 parts by mass of pentaerythritol tetrakis (3-mercaptopropionate) and 55 parts by mass of diethylene glycol dimethacrylate used in Example 6 were used. , 2,6,6-Tetramethyl-1-piperidinoxy was added in an amount of 0.1 to 0.5% by mass to obtain a sample. Furthermore, 0.1 mass% of α-phenyl-Nt-butylnitrone was added as a compound (C) to obtain a sample.

Example 8
As a compound (E) having a nitroso group, 45 parts by mass of pentaerythritol tetrakis (3-mercaptopropionate) and 55 parts by mass of diethylene glycol dimethacrylate used in Example 6 were used as a compound (E) having a nitroso group. A sample was obtained by adding 0.1 to 0.5 mass% of benzene. Furthermore, 0.1 mass% of α-phenyl-Nt-butylnitrone was added as a compound (C) to obtain a sample.

Evaluation of Storage Stability Samples obtained in Examples 6 to 8 were placed in a transparent glass tube and allowed to stand indoors, and the time until curing after thickening and gelation was measured visually. The addition amount of the compounds (C) to (E) as the storage stabilizer was evaluated in the case of no addition, 0.1 mass% addition, and 0.5 mass% addition. The results are shown in Table 2.

In Table 2, in Example 6, the addition of the nitrone compound (C) as a storage stabilizer, in Example 7, the addition of the compound (D) having a nitroxide group and the combined use with the compound (C), Example 8 Then, the relationship between the storage stability, that is, the time (days) until curing, by the addition of the compound (E) having a nitroso group and the combined use with the compound (C) can be grasped.
By using these storage stabilizers, a photo-curable resin composition from which a cured product having both scratch resistance and flexibility can be stably stored for a long period of time as compared with the prior art.

The photo-curable resin composition of the present invention is cured by irradiation with active energy rays such as ultraviolet rays, and the cured product has scratch resistance and flexibility. It can be used effectively.
In addition, the photocurable resin composition of the present invention can be stored for a long period of time by adding a storage stabilizer, so that the photocurable resin is excellent in handling property and extremely practical. It can be used as a composition.

Claims (6)

  A photocurable resin composition comprising a compound (A) having two or more thiol groups in the molecule and a compound (B) having two or more methacryloyl groups in the molecule, and the thiol group of the compound (A) The photocurable resin composition whose functional group equivalent ratio of the methacryloyl group of a compound (B) is (A) / (B) = 5 / 95-45 / 55. The photocurable resin composition according to claim 1, wherein the compound (A) is a compound represented by the general formula (I).

[Wherein, Z ¹ is an organic residue having a valence of 2 to 6, n is an integer of 2 to 6 and does not exceed the valence of Z ¹ . X represents -O-CO-, -O-, or -HN-CO-, Y is an alkylene group having 2 to 8 carbon atoms or an arylene group having 6 to 20 carbon atoms, and v is 0. Or it is an integer of 1. ] The photocurable resin composition according to claim 1 or 2, wherein the compound (B) is a compound represented by the general formula (II).

(In the formula, Z ² is a residue obtained by removing a hydroxyl group from a divalent to hexavalent alcohol, m is an integer of 2 to 6, and does not exceed the valence of Z ^2. ) Furthermore, 0.0001-1 mass part of nitrone compound (C) shown by general formula (III) is contained 0.0001-1 mass part with respect to a total of 100 mass parts of compound (A) + compound (B). The photocurable resin composition in any one.

(In the formula, R ¹ and R ² each represent a t-butyl group, a phenyl group, or a naphthyl group.) Furthermore, 0.0001-1 mass part of compound (D) which has a nitroxide group shown by general formula (IV) is contained with respect to a total of 100 mass parts of compound (A) + compound (B). The photocurable resin composition in any one of -4.

(Wherein, R ³ represents any one of OH, COOH, or H.) Furthermore, 0.0001-1 mass part of compound (E) which has a nitroso group shown by general formula (V) is contained with respect to a total of 100 mass parts of compound (A) + compound (B). The photocurable resin composition in any one of -4.
R ⁴ -NO (V)
(In the formula, R ⁴ represents an alkyl group or an aryl group.)