阅读说明：本技术 光固化性的树脂组合物 (Photocurable resin composition ) 是由 爱泽眸 于 2020-06-10 设计创作，主要内容包括：提供光固化性的树脂组合物,在被光照射而固化时,提高从光照射部与遮光部的边界向遮光部内增进的固化性,得到在遮光部内也具有足够的固化宽度的固化体。一种光固化性的树脂组合物,含有：热塑性弹性体；单官能(甲基)丙烯酸单体；第一光引发剂；第二光引发剂,具有与所述第一光引发剂的吸收光谱的最大波长不同的吸收光谱的最大波长；以及荧光剂,所述第一光引发剂的吸收光谱的最大波长在所述荧光剂的发射光谱的波长范围内,且在相对于所述发射光谱的最大波长的发光强度具有10％以上的发光强度的波长范围内,对于使所述树脂组合物固化而得到的厚度为200μm的固化体的光线透过率,在所述第一光引发剂的吸收光谱的最大波长下为60％以上,所述光线透过率在365nm下小于65％。(Provided is a photocurable resin composition which, when cured by light irradiation, increases the curability from the boundary between the light irradiation section and the light shielding section into the light shielding section, and which provides a cured body having a sufficient cure width also in the light shielding section. A photocurable resin composition comprising: a thermoplastic elastomer; a monofunctional (meth) acrylic monomer; a first photoinitiator; a second photoinitiator having a maximum wavelength of an absorption spectrum different from a maximum wavelength of an absorption spectrum of the first photoinitiator; and a fluorescent agent, wherein the maximum wavelength of the absorption spectrum of the first photoinitiator is within the wavelength range of the emission spectrum of the fluorescent agent, and the light transmittance of a cured body having a thickness of 200 μm obtained by curing the resin composition is 60% or more at the maximum wavelength of the absorption spectrum of the first photoinitiator, and the light transmittance is less than 65% at 365nm, within the wavelength range having a light emission intensity of 10% or more with respect to the maximum wavelength of the emission spectrum.)

1. A photocurable resin composition comprising:

a thermoplastic elastomer,

a monofunctional (meth) acrylic monomer,

a first photo-initiator, which is a photo-initiator,

a second photoinitiator having a maximum wavelength of an absorption spectrum different from the maximum wavelength of the absorption spectrum of the first photoinitiator, an

A fluorescent agent;

the photocurable resin composition is characterized in that,

a maximum wavelength of the absorption spectrum of the first photoinitiator is within a wavelength range of an emission spectrum of the fluorescent agent and within a wavelength range having a light emission intensity of 10% or more with respect to a light emission intensity of a maximum wavelength of the emission spectrum,

the cured product having a thickness of 200 [ mu ] m obtained by curing the resin composition has a light transmittance of 60% or more at the maximum wavelength of the absorption spectrum of the first photoinitiator, and the light transmittance is less than 65% at 365 nm.

2. A photocurable resin composition comprising:

a thermoplastic elastomer,

a monofunctional (meth) acrylic monomer,

a photoinitiator, and

a fluorescent agent;

the photocurable resin composition is characterized in that,

the cured product having a thickness of 200 [ mu ] m obtained by curing the resin composition has a light transmittance of 60% or more at the maximum wavelength of the absorption spectrum of the photoinitiator, and the light transmittance is less than 65% at 365 nm.

3. The photocurable resin composition according to claim 1, wherein,

the maximum wavelength of the absorption spectrum of the first photoinitiator is within the range of 400-500nm,

the maximum wavelength of the emission spectrum of the fluorescent agent is within the range of 400-500 nm.

4. The photocurable resin composition according to claim 1 or 3, wherein,

the absorbance of the first photoinitiator at a wavelength of 365nm is 10% or less of the absorbance at the maximum wavelength.

5. The photocurable resin composition according to any one of claims 1-3, wherein,

the light transmittance of a cured product having a thickness of 200 [ mu ] m obtained by curing the resin composition is 80% or more at the maximum wavelength of the absorption spectrum of the first photoinitiator.

6. The photocurable resin composition according to any one of claims 1 to 5, wherein,

the difference between the refractive index value of a cured product of the photocurable resin composition and the refractive index value of a cured product of a photocurable component containing the monofunctional (meth) acrylic monomer is ± 0.006 or less.

7. The photocurable resin composition according to any one of claims 1-6, wherein,

the thermoplastic elastomer is a styrene-based thermoplastic elastomer having a styrene content of 20 mass% or less.

8. The photocurable resin composition according to any one of claims 1-7, wherein,

the first photoinitiator is 0.05 parts by mass or more per 100 parts by mass of the total resin components.

9. The photocurable resin composition according to any one of claims 1-6, wherein,

the fluorescent agent is 0.01 parts by mass or more per 100 parts by mass of the entire resin component.

Technical Field

The present invention relates to a photocurable resin composition having excellent curability in a light shielding portion.

Background

The photocurable resin composition contains a photoinitiator that initiates a reaction by light. Further, a photo radical polymerization initiator as a photoinitiator generates radicals when it is exposed to light of a predetermined wavelength, and the radicals accelerate curing of the photocurable resin composition. Therefore, since radicals are not generated from the photo radical polymerization initiator in a portion not exposed to light, there is a possibility that curing is accelerated until the radicals disappear in a light-shielded region adjacent to the portion exposed to light, but it is difficult to bring the photocurable resin composition into a desired cured state.

As a method for curing a portion which does not encounter light (hereinafter referred to as "light shielding portion"), japanese patent application laid-open No. 2014-095080 (patent document 1) discloses that a thermal radical initiator (for example, an organic peroxide or the like) is added in addition to a photo radical initiator, and a heating step is further performed or a thermal radical reaction is performed by utilizing reaction heat generated at the photo radical reaction. However, in particular, when the heating step is performed, there is a risk that the substrate itself coated with the photocurable resin composition is deformed by heat. Therefore, when a thermal radical initiator that generates radicals at a low temperature is used, there is a risk that the storage stability of the photocurable resin composition is deteriorated, whereas when a thermal radical initiator that generates radicals at a high temperature is used to maintain the storage stability, it takes time to cure the light shielding portion.

Further, a method of curing a photocurable resin composition by moisture by including a substance having a moisture-reactive group is also considered. However, the substance having a moisture-reactive group has a limitation in selection of a material, and further, has a risk of being cured during production and storage. In addition, in the method of adding a substance having an epoxy group to a photocurable resin composition to carry out a photocationic curing, since an acid is generated at the time of curing, there is a risk that a metal is corroded when a metal material is used around the periphery to which the photocurable resin composition is applied.

International publication No. 2013/105163 (patent document 2) discloses an ultraviolet-curable adhesive that can bond an optical substrate to a light-shielding portion by combining an organic compound (so-called fluorescent agent) that absorbs ultraviolet light and emits light with a photoinitiator. However, in the case of a combination of an organic compound (so-called fluorescent agent) which absorbs ultraviolet light to emit light and a photoinitiator, curing can be performed only by about 1mm from the boundary between the light irradiation part and the light shielding part into the light shielding part. Therefore, when the ultraviolet curing adhesive is used for, for example, moisture-proof insulation protection of a component on which a substrate is mounted, if the ultraviolet curing adhesive is applied to the lower side of the component mounted on an opaque base material, there is a possibility that the ultraviolet curing adhesive is insufficiently cured in a portion shielded from light by the component.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2014-095080

Patent document 2: international publication No. 2013/105163

Disclosure of Invention

Problems to be solved by the invention

In addition, when a conventional photocurable resin composition is cured by light irradiation, the curability of the composition increases from the boundary between the light irradiation portion and the light shielding portion toward the inside of the light shielding portion.

The present invention has been made to solve the above problems. That is, an object is to provide a photocurable resin composition which, when cured by light irradiation, improves curability that increases from the boundary between the light irradiation section and the light shielding section toward the inside of the light shielding section.

Means for solving the problems

The photocurable resin composition of the present invention for achieving the above object is as follows.

The photocurable resin composition of the present invention comprises: the photocurable resin composition is characterized in that the maximum wavelength of the absorption spectrum of the first photoinitiator is within the wavelength range of the emission spectrum of the fluorescent agent, and the light transmittance of a cured body having a thickness of 200 [ mu ] m obtained by curing the resin composition is 60% or more at the maximum wavelength of the absorption spectrum of the first photoinitiator, and the light transmittance is less than 65% at 365nm, within the wavelength range having a light emission intensity of 10% or more with respect to the light emission intensity of the maximum wavelength of the emission spectrum. The phosphor in the resin composition emits light by light irradiation by making the maximum wavelength of the absorption spectrum of the first photoinitiator in the wavelength range of the predetermined intensity of the emission spectrum of the phosphor, and the first photoinitiator absorbs light to generate radicals when the emission spectrum reaches the light shielding portion, whereby curing of the resin composition is improved even in the light shielding portion. The resin composition contains a thermoplastic elastomer, but the thermoplastic elastomer has a hard segment and a soft segment in a microphase-separated state. The cured product is a cured product having a hard segment and a soft segment of a thermoplastic elastomer and a photocurable component containing a monofunctional (meth) acrylic monomer in a microphase-separated state. Therefore, it is considered that light generated by light emission of the fluorescent agent is scattered by the light generated by the microphase-separated structure, and directed to a light-shielding portion extending in a horizontal direction with respect to an irradiation direction of light irradiated for curing. Still further, since the light transmittance of the cured product having a thickness of 200 μm obtained by curing the resin composition is 60% or more at the maximum wavelength of the absorption spectrum of the first photoinitiator and is less than 65% at 365nm, light generated by emission of a fluorescent agent is directed from the boundary between the light irradiation part and the light shielding part into the light shielding part, and passes through the cured part of the resin composition to reach the uncured part of the resin composition distant from the part which encounters light, the curing of the resin composition in the light shielding part is improved. As a result, a cured body having a sufficient curing width in the light-shielding portion was obtained. Further, the resin composition contains a thermoplastic elastomer and a monofunctional (meth) acrylic monomer, and thus a cured product having excellent moisture resistance and flexibility is obtained.

Another curable resin composition of the present invention contains: the photocurable resin composition is characterized in that the light transmittance of a cured body having a thickness of 200 [ mu ] m obtained by curing the resin composition is 60% or more at the maximum wavelength of the absorption spectrum of the photoinitiator, and the light transmittance is less than 65% at 365 nm. The light transmittance of a cured body having a thickness of 200 μm obtained by curing the resin composition is 60% or more at the maximum wavelength of the absorption spectrum of the photoinitiator, and the light transmittance is less than 65% at 365nm, whereby light generated by emission of a fluorescent agent is directed from the boundary between a light irradiation part and a light shielding part into the light shielding part, passes through a cured part of the resin composition, and reaches an uncured part of the resin composition far from the part which meets the light, so that curing of the resin composition in the light shielding part is improved. As a result, a cured body having a sufficient curing width in the light-shielding portion was obtained. The resin composition contains a thermoplastic elastomer, but the thermoplastic elastomer has a hard segment and a soft segment in a microphase-separated state. The cured product is a cured product having a hard segment and a soft segment of a thermoplastic elastomer and a photocurable component containing a monofunctional (meth) acrylic monomer in a microphase-separated state. Therefore, it is considered that light generated by light emission of the fluorescent agent is scattered by the microphase-separated structure and directed to a light-shielding portion extending in a horizontal direction with respect to an irradiation direction of light irradiated for curing. In addition, the resin composition contains the thermoplastic elastomer and the monofunctional (meth) acrylic monomer, and thus a cured product having excellent moisture resistance and flexibility is obtained as compared with a cured product of other resin components combined.

The maximum wavelength of the absorption spectrum of the first photoinitiator can be within a wavelength range of 400-500nm, and the maximum wavelength of the emission spectrum of the fluorescent agent is within a wavelength range of 400-500 nm. Thus, the fluorescent agent in the resin composition emits light by light irradiation, and when the emission spectrum reaches the light-shielding portion, the first photoinitiator absorbs light to generate radicals, so that curing of the resin composition in the light-shielding portion is promoted. The absorption spectrum of the first photoinitiator has a maximum wavelength in the wavelength range of 400 to 500nm, and generally has an absorption smaller than the maximum in the wavelength range of 350 to 400nm in the vicinity thereof. Thus, when an LED light source having a wavelength of 365nm is used for curing the resin composition, the first photoinitiator can be reduced from absorbing ultraviolet rays emitted from the light source. Therefore, the light-shielding curability of the resin composition can be improved without hindering the light absorption of the fluorescent agent.

Particularly preferably, the absorbance of the first photoinitiator at a wavelength of 365nm is 10% or less of the absorbance at the maximum wavelength.

Preferably, the light transmittance of a cured product having a thickness of 200 μm obtained by curing the resin composition is 80% or more at the maximum wavelength of the absorption spectrum of the first photoinitiator. This is because if the light transmittance at the maximum wavelength of the absorption spectrum of the first photoinitiator is 80% or more, the maximum length of the cured portion of the light shielding portion can be further increased.

The difference between the refractive index value of a cured product of the photocurable resin composition and the refractive index value of a cured product of a photocurable component containing the monofunctional (meth) acrylic monomer is ± 0.006 or less. Thereby, the emitted light of the fluorescent agent is directed from the boundary of the light irradiation portion and the light shielding portion toward the inside of the light shielding portion, passes through the cured portion of the resin composition, and reaches the uncured portion of the resin composition, whereby the curing of the resin composition of the light shielding portion is promoted. As a result, a cured body having a sufficient curing width in the light-shielding portion was obtained.

The thermoplastic elastomer is a styrene-based thermoplastic elastomer having a styrene content of 20 mass% or less. Thus, the light transmittance of a cured product having a thickness of 200 μm obtained by curing the resin composition can be improved even in combination with a monofunctional (meth) acrylic monomer which is easy to improve flexibility, as compared with the case of using a styrene-based thermoplastic elastomer having a styrene content greater than the above value. Therefore, the emission light of the fluorescent agent can pass through the cured portion of the resin composition toward the inside of the light shielding portion from the boundary between the light irradiation portion and the light shielding portion to reach the uncured portion of the resin composition of the light shielding portion, and the curing of the resin composition is improved. As a result, a cured body having a sufficient curing width in the light-shielding portion and excellent flexibility can be obtained.

The first photoinitiator is 0.05 parts by mass or more per 100 parts by mass of the total resin component, and thus a cured body having a sufficient curing width from the boundary between the light irradiation section and the light shielding section toward the inside of the light shielding section is obtained as compared with the case where the amount of the first photoinitiator is less than the above-mentioned amount of addition.

The phosphor is 0.01 parts by mass or more per 100 parts by mass of the entire resin component, and thus a cured body having a sufficient curing width from the boundary between the light irradiation part and the light shielding part toward the inside of the light shielding part is obtained as compared with the case where the amount of the phosphor is less than the above-mentioned amount of addition.

Effects of the invention

The photocurable resin composition of the present invention provides a cured body which has improved curability from the boundary between the light irradiation part and the light shielding part toward the inside of the light shielding part and has a sufficient curing width in the light shielding part when cured by light irradiation. The cured product of the photocurable resin composition of the present invention after curing is flexible and has excellent moisture resistance and flexibility.

Drawings

Fig. 1 is a schematic cross-sectional view illustrating a measurement method for evaluating curability of a light shielding portion, which is one of the evaluation methods of examples in the present specification.

FIG. 2 is a schematic cross-sectional view illustrating a state where an uncured portion is removed after light irradiation in the measurement method illustrated in FIG. 1.

Fig. 3 is a graph showing an absorption spectrum of Camphorquinone (CQ) of the photoinitiator used in the examples of the present specification and an emission spectrum of N, N '-diphenyl-N, N' -di (m-tolyl) benzidine (TPD) of the fluorescent agent.

FIG. 4 is a graph showing absorption spectra of phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide (Omnirad819), 2-dimethylamino-2- (4-methyl-benzyl) -1- (4-morpholin-4-phenyl) -butan-1-one (Irgacure397), N '-diphenyl-N, N' -di (m-tolyl) benzidine (TPD) as a fluorescent agent.

FIG. 5 is a graph showing absorption spectra of cured products of sample 1 and sample 9.

Detailed Description

[ Photocurable resin composition ]

The photocurable resin composition of the present invention, which contains a thermoplastic elastomer, a monofunctional (meth) acrylic monomer, a photoinitiator, and a fluorescent agent, is characterized in that the light transmittance of a cured product having a thickness of 200 μm obtained by curing the resin composition is 60% or more at the maximum wavelength of the absorption spectrum of the first photoinitiator, and the light transmittance is less than 65% at 365 nm.

Another photocurable resin composition of the present invention comprises a thermoplastic elastomer, a monofunctional (meth) acrylic monomer, a first photoinitiator, a second photoinitiator having a maximum wavelength of an absorption spectrum different from that of the first photoinitiator, and a fluorescent agent, and the photocurable resin composition, characterized in that the maximum wavelength of the absorption spectrum of the first photoinitiator is within the wavelength range of the emission spectrum of the fluorescent agent, and in a wavelength range having a luminous intensity of 10% or more with respect to a luminous intensity of a maximum wavelength of the emission spectrum, the light transmittance of a cured product having a thickness of 200 μm obtained by curing the resin composition, the absorption spectrum of the first photoinitiator is 60% or more at the maximum wavelength, and the light transmittance is less than 65% at 365 nm.

The light transmittance of a cured body having a thickness of 200 μm obtained by curing the resin composition is 60% or more at the maximum wavelength of the absorption spectrum of the first photoinitiator, and the light transmittance is less than 65% at 365nm, whereby the emission light of the fluorescent agent is directed from the boundary between the light irradiation part and the light shielding part into the light shielding part, passes through the cured part of the resin composition, and reaches the uncured part of the resin composition in the light shielding part, whereby the curing of the resin composition is improved. As a result, a cured body having a sufficient curing width in the light-shielding portion is obtained. When the light transmittance is less than 65% at 365nm, it means that a fluorescent agent which absorbs 365nm light and a photoinitiator or a decomposition product of the photoinitiator are contained in appropriate amounts.

The light transmittance at the maximum wavelength of the absorption spectrum of the first photoinitiator has no upper limit, but is, for example, 99% or less. The light transmittance at 365nm also has no lower limit, and is, for example, 0.1% or more.

The light transmittance at the maximum wavelength of the absorption spectrum of the first photoinitiator is preferably 80% or more. Thus, the curing width in the light shielding portion can be further increased. The light transmittance at the maximum wavelength of the absorption spectrum of the first photoinitiator is preferably 95% or less.

On the other hand, the light transmittance at 365nm is preferably 50% or less. The light transmittance at 365nm is preferably 10% or more.

Further, the first photoinitiator emits light when the maximum wavelength of the absorption spectrum of the first photoinitiator is within a wavelength range of a predetermined intensity of the emission spectrum of the fluorescent agent by light irradiation, and absorbs light to generate radicals when the emission spectrum reaches the light shielding portion, whereby the curing of the resin composition is improved even in the light shielding portion.

The resin composition contains a thermoplastic elastomer and a monofunctional (meth) acrylic monomer, and thus a cured product having excellent moisture resistance and flexibility is obtained.

Next, the components contained in the photocurable resin composition will be described.

< thermoplastic elastomer >

Examples of the thermoplastic elastomer include styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, ester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, amide-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, fluororesin-based thermoplastic elastomers, and ionomer-based thermoplastic elastomers. As the thermoplastic elastomer of the present invention, a styrene-based thermoplastic elastomer is preferable. The thermoplastic elastomer has a hard segment and a soft segment in a microphase-separated state in the resin composition. The cured product further comprises a hard segment and a soft segment of the thermoplastic elastomer in a microphase separated state, and a cured product of a photocurable component containing a monofunctional (meth) acrylic monomer. Therefore, it is considered that light generated by light emission of the fluorescent agent is scattered by the light generated by the microphase-separated structure and directed toward a light-shielding portion which is horizontally extended with respect to an irradiation direction of light irradiated for curing. Further, it was confirmed that the resin composition of the present invention has the above microphase-separated structure by analyzing the cured product with a Transmission Electron Microscope (TEM).

The styrene-based thermoplastic elastomer is dissolved in a monofunctional (meth) acrylic monomer described later in the photocurable resin composition. In addition, the styrenic thermoplastic elastomer is a component that is dissolved in the monofunctional (meth) acrylic monomer and imparts rubber elasticity (flexibility and extensibility) to the cured body. In the present invention, the dissolved state is a state in which the liquid is uniformly formed as a whole, and the liquid is preferably colorless and transparent, but may have a predetermined transmittance even when white turbidity or suspension of another color is present.

The styrene-based thermoplastic elastomer is a solid alone and therefore does not have adhesiveness at normal temperature, but can be contained as one component of a photocurable resin composition having adhesiveness by dissolving the styrene-based thermoplastic elastomer in the monofunctional (meth) acrylic monomer to uniformly disperse the styrene-based thermoplastic elastomer in the photocurable resin composition and a cured product thereof.

The amount of the styrenic thermoplastic elastomer added is preferably 2 to 60 parts by mass, more preferably 2 to 30 parts by mass, based on 100 parts by mass of the total mass of the thermoplastic elastomer and the monofunctional (meth) acrylic monomer, from the viewpoint of transparency of a cured product after curing of the photocurable resin composition.

Specific examples of the styrene-based thermoplastic elastomer include a styrene-butadiene-styrene block copolymer (SBS), a styrene-isoprene-styrene block copolymer (SIS), a styrene-ethylene-butylene-styrene block copolymer (SEBS), a styrene-ethylene-propylene-styrene block copolymer (SEPS), a styrene-isobutylene-styrene block copolymer (SIBS), a styrene-ethylene-propylene-styrene block copolymer (SEEPS), and modifications thereof.

Among them, SEBS, SEPS, SIBS, and SEEPS having no unsaturated bond in the soft segment are preferable from the viewpoint that the cured product of the photocurable resin composition after curing has both light transmittance and flexibility in the above range. In addition, they are preferable because they are excellent in weather resistance. Furthermore, the use of SEBS and SEPS in which the soft segment content is high makes it possible to improve the transparency of the cured product.

Further, since the thermoplastic elastomer is a styrene-based thermoplastic elastomer having a styrene content of 20% by mass or less, the light transmittance of a cured product having a thickness of 200 μm obtained by curing the resin composition can be easily controlled to 60% or more at the maximum wavelength of the absorption spectrum of the first photoinitiator and to less than 65% at 365nm even when combined with a relatively wide range of monofunctional (meth) acrylic monomers, as compared with the case of using a styrene-based thermoplastic elastomer having a styrene content greater than the above-mentioned value.

In the present specification, the weight average molecular weight of the styrenic thermoplastic elastomer is determined using a GPC method (Gel Permeation Chromatography; Gel Permeation Chromatography) based on a calibration curve (standard curve) determined by standard polystyrene. In the present invention, a styrene-based thermoplastic elastomer having a weight average molecular weight of less than 20 ten thousand is used, but it is preferable because it is easy to adjust the viscosity to a viscosity suitable for application.

< monofunctional (meth) acrylic monomer >

Examples of the monofunctional (meth) acrylic monomer include a monofunctional alicyclic (meth) acrylate monomer, a monofunctional aliphatic (meth) acrylate monomer, and a monofunctional highly polar monomer.

Here, the "monofunctional alicyclic (meth) acrylate monomer" means that the monofunctional alicyclic acrylate monomer and the monofunctional alicyclic methacrylate monomer are included. "monofunctional aliphatic (meth) acrylate monomer" is meant to include both monofunctional aliphatic acrylate monomers as well as monofunctional aliphatic methacrylate monomers. The "monofunctional highly polar monomer" which may be contained in the present invention means a monofunctional acrylate monomer containing a polar group, a methacrylate monomer, or a monomer containing an acrylamide group having a monofunctional function.

Monofunctional alicyclic (meth) acrylate monomer:

the monofunctional alicyclic (meth) acrylate monomer is a liquid composition and is a component for dissolving the thermoplastic elastomer. Further, by blending the monofunctional alicyclic (meth) acrylate monomer, the refractive index of the cured product after curing of the photocurable resin composition can be adjusted to a high value. Further, the cured product can be made tough to increase the young's modulus, and further, the adhesive strength can be increased, and the adhesive remains when the cured product is peeled off from the adherend. Further, if the ratio of the component is increased, moisture resistance can be improved.

Specific examples of the monofunctional alicyclic (meth) acrylate monomer include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, 3, 5-trimethylcyclohexyl acrylate, and 4-t-butylcyclohexyl acrylate.

Monofunctional aliphatic (meth) acrylate monomer:

the monofunctional aliphatic (meth) acrylate monomer is a liquid composition, and is a component for dissolving the thermoplastic elastomer together with the monofunctional alicyclic (meth) acrylate monomer. By blending a monofunctional aliphatic (meth) acrylate monomer, the refractive index of a cured product obtained after curing of the photocurable resin composition can be adjusted to a low value. Further, the flexibility of the cured product can be improved, and the Young's modulus can be reduced.

As the monofunctional aliphatic (meth) acrylate monomer, there are specifically mentioned: aliphatic ether (meth) acrylate monomers such as ethoxydiglycol acrylate, 2-ethylhexyl diglycol acrylate and butoxyethyl acrylate; and aliphatic hydrocarbon (meth) acrylate monomers such as lauryl acrylate, stearyl acrylate, isostearyl acrylate, decyl acrylate, isodecyl acrylate, isononyl acrylate, and n-octyl acrylate. By using the aliphatic hydrocarbon (meth) acrylate monomer, the compatibility with the soft segment of the thermoplastic elastomer is increased, and the viscosity of the photocurable resin composition can be reduced.

Monofunctional highly polar monomer:

the monofunctional highly polar monomer is a liquid composition, and the addition of the monofunctional highly polar monomer can improve the adhesion of a cured product obtained after curing of the photocurable resin composition.

Specific examples of the monofunctional highly polar monomer include a hydroxyl group-containing (meth) acrylate monomer, a glycidyl group-containing (meth) acrylate monomer, an acrylamide group-containing monomer, a tertiary amino group-containing (meth) acrylate monomer, and an imide group-containing (meth) acrylate monomer. From the viewpoint of improving storage stability and adhesion in the photocurable resin composition, nitrogen-containing monomers such as an acrylamide group-containing monomer, a tertiary amino group-containing (meth) acrylate monomer, and an imide group-containing (meth) acrylate monomer are preferable. Examples of the monofunctional highly polar monomer include acryloylmorpholine, dimethylaminoethyl (meth) acrylate, and N-acryloyloxyethylhexahydrophthalimide. Particularly, when the object to be coated is polyimide, imide acrylate typified by N-acryloyloxyethylhexahydrophthalimide is preferably used.

From the viewpoint of adhesiveness, the monofunctional highly polar monomer is preferably 0.5 to 12.75% by mass, more preferably 2 to 8.5% by mass in the photocurable resin composition.

The photocurable resin composition of the present invention may further contain a polyfunctional monomer such as a polyfunctional aliphatic (meth) acrylate monomer, a polyfunctional cyclic (meth) acrylate monomer, or bismaleimide. From the viewpoint of the strength of a cured product after curing of the photocurable resin composition and the reactivity of the photocurable resin composition, it is preferable that 1 or more of the polyfunctional aliphatic (meth) acrylate monomer, the polyfunctional cyclic (meth) acrylate monomer, and the bismaleimide be present in an amount of 0 to 4.25 mass% by weight, alone or in combination, in the photocurable resin composition. When the content is more than 4.25% by mass, the residual viscosity of the cured product is small, and the cured product may shrink (warp) or be inferior in bending resistance.

Specific examples of the polyfunctional aliphatic (meth) acrylate monomer include bifunctional aliphatic (meth) acrylate monomers. Examples of the bifunctional aliphatic (meth) acrylate monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, glycerin di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 3-methyl-1, 5-pentanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 9-nonanediol di (meth) acrylate, and 1, 10-decanediol di (meth) acrylate. Since the compatibility with the soft segment of the thermoplastic elastomer is relatively high, a bifunctional aliphatic hydrocarbon di (meth) acrylate monomer having a reactive group at both ends is preferable.

Specific examples of the polyfunctional cyclic (meth) acrylate monomer include ethoxylated isocyanuric acid di/tri (meth) acrylate and epsilon-caprolactone-modified tris- (2-acryloyloxyethyl) isocyanurate. The polyfunctional cyclic (meth) acrylate monomer is preferably a tris (2-hydroxyethyl) isocyanurate (meth) acrylate monomer in view of improving adhesiveness.

Examples of the bismaleimide include 4, 4 '-diphenylmethane bismaleimide, 4-methyl-1, 3-phenylene bismaleimide, 2-bis [4- (4-maleimidophenoxy) phenyl ] propane, bis (3-ethyl-5-methyl-4-maleimidophenyl) methane, 1, 6-bis (maleimide) hexane, and 1, 6' -bismaleimide- (2, 2, 4-trimethyl) hexane. From the viewpoint of hardly inhibiting the compatibility and photocurability of the photocurable resin composition, aliphatic bismaleimides such as 1, 6-bis (maleimide) hexane and 1, 6' -bismaleimide- (2, 2, 4-trimethyl) hexane are preferable.

Further, from the viewpoint of improving curability of the light shielding portion of the photocurable resin composition of the present invention, a difference between a refractive index value of a cured product of the photocurable resin composition and a refractive index value of a cured product of a photocurable component containing the monofunctional (meth) acrylic monomer is preferably ± 0.006 or less, and more preferably ± 0.002 or less.

< photoinitiator >

The photoinitiator of the present invention has a first photoinitiator and a second photoinitiator having a maximum wavelength of an absorption spectrum different from that of the first photoinitiator. In addition, the case of separately expressing "photoinitiator" means an entirety including the above-described first photoinitiator and second photoinitiator.

First photoinitiator

The first photoinitiator has a maximum wavelength of an absorption spectrum at a visible light wavelength (400 to 800nm), and preferably has a maximum wavelength of an absorption spectrum at 400 to 500 nm. The absorption spectrum was obtained by measuring the absorbance of the test solution at a wavelength of 300 to 800nm at 23 ℃ using a unit cell having an optical path length of 1cm and an ultraviolet-visible spectrophotometer ("UV-1600 PC" manufactured by Shimadzu corporation) with tetrahydrofuran as a solvent, with the first photoinitiator adjusted to 0.01 mass%. Further, with respect to the first photoinitiator, the maximum wavelength of the absorption spectrum indicates the maximum wavelength in an absorption region where absorption is performed by excitation from the ground state S0 to the excited state S1 and appears on the longest wavelength side.

The first photoinitiator may generate radicals at visible light wavelengths (400 to 800nm), and examples thereof include: acylphosphine photoinitiators such as 2, 4, 6-trimethylbenzoyldiphenylphosphine oxide; and hydrogen abstraction type photoinitiators such as thioxanthone, anthraquinone, 2-aminoanthraquinone, camphorquinone, methyl glyoxylate, and 1-phenyl-1, 2-propanedione. However, in the present invention, at least a part of the wavelength region of the emission spectrum of the fluorescent agent described later must overlap. In the present invention, particularly in the case of using a fluorescent agent N, N '-diphenyl-N, N' -di (m-tolyl) benzidine (TPD) in which the wavelength of the curing light is 365nm and the maximum wavelength of the emission spectrum is 400 to 500nm, as the first photoinitiator, Camphorquinone (CQ) is preferable in which the respective wavelength regions partially overlap as shown in fig. 3 and the absorption of light in the wavelength region of the curing light (for example, 365nm in the case of an LED light source) is small.

From the viewpoint of improving curability of the light-shielding portion of the photocurable resin composition, the first photoinitiator is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and particularly preferably 0.2 parts by mass or more, per 100 parts by mass of the total resin components. Here, the "resin component" includes a thermoplastic elastomer and a monofunctional (meth) acrylic monomer. The first photoinitiator is preferably 1 part by mass or less based on 100 parts by mass of the total resin components.

Second photoinitiator

The second photoinitiator has a maximum wavelength that is different from an absorption spectrum of the first photoinitiator. More specifically, the photoinitiator has an absorption spectrum with a maximum wavelength of less than 400nm and generates radicals by irradiation of ultraviolet rays. The absorption spectrum was measured by the same method as that of the first photoinitiator. Examples of the second photoinitiator include photopolymerization initiators such as benzophenones, thioxanthones, acetophenones, acylphosphines, oxime esters, and alkylbenzophenones. The amount of the second photoinitiator added is preferably 0.1 to 5 parts by mass, and more preferably 0.4 to 2 parts by mass, based on 100 parts by mass of the resin component, from the viewpoints of curability of a portion exposed to light and light transmittance.

< fluorescent agent >

The fluorescent agent used in the present invention may be any material that absorbs light irradiated for curing and emits light at a predetermined wavelength that can be absorbed by the first photoinitiator, and examples thereof include naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, tetracene derivatives, coronene derivatives, chrysene derivatives, triphenylene derivatives, coumarin derivatives, oxazole derivatives, carbazole derivatives, pyridine derivatives, porphyrin derivatives, fluorene derivatives, fluorescein derivatives, arylamine derivatives, rubrene derivatives, quinacridone derivatives, phthalocyanine derivatives, and metal complexes containing rare earth complexes. Among them, substances which absorb ultraviolet rays and emit blue light are preferable, and examples thereof include 7-hydroxy-4-methylcoumarin, 9, 10-bis (phenylethynyl) anthracene, triphenylamine, and N, N '-diphenyl-N, N' -di (m-tolyl) benzidine (TPD).

The fluorescent agent used in the present invention has a maximum wavelength of an emission spectrum in a visible light wavelength range (400 to 800nm), and preferably has a maximum wavelength of an emission spectrum in a wavelength range of 400 to 500 nm. The emission spectrum was obtained by measuring an emission spectrum having an excitation wavelength of 352nm to 800nm at 23 ℃ using a spectrofluorometer ("RF-6000", manufactured by Shimadzu corporation) using acetonitrile as a solvent, a test solution adjusted to 0.005% by mass of a fluorescent agent, and a cell having an optical path length of 1 cm. Further, the maximum wavelength of the emission spectrum of the fluorescent agent means the maximum wavelength at which the emission intensity is maximum in the region of the emission spectrum.

From the viewpoint of improving curability of the light-shielding portion of the photocurable resin composition, the fluorescent agent is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, and on the other hand, preferably 0.22 parts by mass or less, more preferably 0.08 parts by mass or less, and particularly preferably 0.04 parts by mass or less, based on 100 parts by mass of the total resin components.

When a fluorescent agent that absorbs light in a wavelength region of curing light (for example, 365nm in the case of an LED light source) is contained in a predetermined amount, the light transmittance of 365nm light to a cured product having a thickness of 200 μm obtained by curing the resin composition falls within a predetermined range.

Other components:

the photocurable resin composition of the present invention can also be appropriately blended with other components such as various additives without departing from the scope of the present invention. Examples thereof include: thixotropic agents such as silica and alumina; plasticizers such as olefin oils and paraffin oils; silane coupling agents or inhibitors; defoaming agents; a light stabilizer; an antioxidant; an antistatic agent; fillers, and the like.

The above embodiments are illustrative of the present invention, and modifications of the embodiments, additions and combinations of known techniques, and the like may be made without departing from the spirit of the present invention, and these techniques are also included in the scope of the present invention.

Examples

The present invention will be described in further detail based on examples (comparative examples). The following photocurable resin compositions and cured products thereof of samples 1 to 33 were prepared and evaluated by the following evaluation methods. Further, each operation and evaluation was carried out at room temperature (23 ℃ C.) unless otherwise stated.

< preparation of sample >

Samples were prepared as follows.

Sample 1:

lauryl acrylate (abbreviated as "LA" in the table) and isobornyl acrylate (abbreviated as "IBXA" in the table) were prepared as monofunctional (meth) acrylic monomers, and 1, 9-nonanediol diacrylate (abbreviated as "NDDA" in the table) was prepared as a bifunctional aliphatic acrylic monomer. Next, SIBS (styrene-isobutylene-styrene block copolymer) (trade name "SIBSTAR 102T", manufactured by Kaneka corporation, styrene content 15 mass%) was added as a thermoplastic elastomer to the above-mentioned monomers, and stirred for 24 hours, thereby dissolving the thermoplastic elastomer in the above-mentioned monomers. The blending ratio in this case is shown in Table 1. Then, when the "resin component" composed of the monomer and the thermoplastic elastomer was set to 100 parts by mass, phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide (product "Ominirad 819", produced by igmesesins b.v.) as a photo radical polymerization initiator was added as a second photoinitiator to the resin component in the amount of addition shown in table 1, to obtain a photocurable resin composition of sample 1.

The obtained photocurable resin composition of sample 1 was irradiated with ultraviolet rays under the following conditions to form a cured product of sample 1.

2-4 of a sample:

as shown in table 1, photocurable resin compositions of samples 2 to 4 were prepared in the same manner as in sample 1 except that the type of the thermosetting elastomer was changed to a styrene-ethylene-butylene-styrene block copolymer (SEBS) (trade name "KRAITONG 1645", manufactured by Kraton corporation, styrene content 13 mass%) or not to any thermoplastic elastomer instead of SIBS (styrene-isobutylene-styrene block copolymer) (trade name "SIBSTAR 102T", manufactured by Kaneka corporation, styrene content 15 mass%), or a styrene-ethylene-propylene-styrene block copolymer (SEPS) (trade name "SEPTON 2063", manufactured by kohly corporation, styrene content 13 mass%). The photocurable resin compositions of samples 2 to 4 were irradiated with ultraviolet rays in the same manner as sample 1, and cured products of samples 2 to 4 were formed on the polyimide film and the polyethylene terephthalate film.

Samples 5 and 6:

as shown in table 1, photocurable resin compositions of samples 5 and 6 were prepared in the same manner as in sample 1 except that the thermosetting elastomer of sample 1 was changed to a styrene-ethylene-propylene-styrene block copolymer (SEPS) (trade name "SEPTON 2063", manufactured by sekuly corporation, having a styrene content of 13 mass%) and N, N '-diphenyl-N, N' -di (m-tolyl) benzidine (abbreviated as "TPD" in the table) was added as a fluorescent agent in the amount shown in table 2. The photocurable resin compositions of samples 5 and 6 were also irradiated with ultraviolet rays in the same manner as sample 1, and cured products of samples 5 and 6 were formed on the polyimide film and the polyethylene terephthalate film.

Sample 7:

as shown in table 2, a photocurable resin composition of sample 7 was prepared in the same manner as in sample 1 except that the thermosetting elastomer of sample 1 was changed to a styrene-ethylene-propylene-styrene block copolymer (SEPS) (trade name "SEPTON 2063", manufactured by sekuly corporation, having a styrene content of 13 mass%), N '-diphenyl-N, N' -di (m-tolyl) benzidine (TPD) was added as a fluorescent agent in the amount shown in table 2, and camphorquinone (abbreviated as "CQ" in the table) was added as a first photoinitiator in place of the second photoinitiator in the amount shown in table 2. The photocurable resin composition of sample 7 was also irradiated with ultraviolet rays in the same manner as in sample 1, and a cured product of sample 7 was formed on the polyimide film and the polyethylene terephthalate film.

Sample 8:

lauryl acrylate and isobornyl acrylate were prepared as monofunctional (meth) acrylic monomers, and 1, 9-nonanediol diacrylate was prepared as a bifunctional aliphatic acrylic monomer. Next, a styrene-ethylene-propylene-styrene block copolymer (SEPS) (trade name "SEPTON 2063", manufactured by korea corporation, styrene content 13 mass%) was added as a thermoplastic elastomer to the above monomers, and stirred for 24 hours, thereby dissolving the thermoplastic elastomer in the above monomers. The blending ratio in this case is shown in Table 2. When the "resin component" composed of the above-mentioned monomer and the thermoplastic elastomer is assumed to be 100 parts by mass, N '-diphenyl-N, N' -di (m-tolyl) benzidine (TPD) is added as a fluorescent agent in an amount shown in table 2, and phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide (product name "Ominirad 819", manufactured by igmesens b.v.) as a photo radical polymerization initiator and Camphorquinone (CQ) as a first photoinitiator are added to the resin component in amounts shown in table 2, respectively, to obtain a photocurable resin composition of sample 8.

The obtained photocurable resin composition of sample 8 was irradiated with ultraviolet light under the conditions described below to form a cured product of sample 8.

Sample 9-10:

photocurable resin compositions of samples 9 to 10 were prepared in the same manner as in sample 8, except that the amount of the fluorescent agent added was changed to that shown in table 2, as shown in table 2. The photocurable resin compositions of samples 9 to 10 were also irradiated with ultraviolet rays in the same manner as in sample 8, and cured products of samples 9 to 10 were formed on the polyimide film and the polyethylene terephthalate film.

Samples 11 to 14:

photocurable resin compositions of samples 11 to 14 were prepared in the same manner as sample 8, except that the amount of the fluorescent agent added was changed from 0.001 part by mass to 0.020 part by mass as shown in table 3, and the amount of Camphorquinone (CQ) added as the first photoinitiator was changed as shown in table 3. The photocurable resin compositions of samples 11 to 14 were also irradiated with ultraviolet rays in the same manner as in sample 8, and cured products of samples 11 to 14 were formed on the polyimide film and the polyethylene terephthalate film.

15-17 parts of sample:

photocurable resin compositions of samples 15 to 17 were prepared in the same manner as in sample 8, except that the amount of Camphorquinone (CQ) added as the first photoinitiator was changed from 0.43 parts by mass to 0.20 parts by mass as shown in table 4, and the amount of fluorescent agent added as shown in table 4. The photocurable resin compositions of samples 15 to 17 were also irradiated with ultraviolet rays in the same manner as in sample 8, and cured products of samples 15 to 17 were formed on the polyimide film and the polyethylene terephthalate film.

18-20 parts of a sample:

photocurable resin compositions of samples 18 to 20 were prepared in the same manner as in sample 8, except that the amount of the fluorescent agent added was changed from 0.001 part by mass to 0.020 part by mass, the amount of Camphorquinone (CQ) added as the first photoinitiator was changed as shown in table 3, and the amount of the basic tertiary amine 2- (dimethylamino) ethyl methacrylate added as the reducing agent for camphorquinone was changed as shown in table 3, as shown in table 4. The photocurable resin compositions of samples 18 to 20 were irradiated with ultraviolet rays in the same manner as in sample 8, and cured products of samples 18 to 20 were formed on the polyimide film and the polyethylene terephthalate film.

Sample 21:

a photocurable resin composition of sample 21 was prepared in the same manner as in sample 8, except that the amount of the fluorescent agent was changed from 0.001 parts by mass to 0.040 parts by mass, the amount of the phenyl bis (2, 4, 6-trimethylbenzoyl) phosphine oxide (trade name "Ominirad 819", produced by igmesesins b.v.) as the photo radical polymerization initiator was changed to 2-dimethylamino-2- (4-methyl-benzyl) -1- (4-morpholin-4-phenyl) -butan-1-one (trade name "Irgacure 397", produced by BASF japan corporation) as the second photoinitiator, and the amount of the fluorescent agent added was changed as shown in table 5. The photocurable resin composition of sample 21 was also irradiated with ultraviolet rays in the same manner as in sample 8, and a cured product of sample 21 was formed on the polyimide film and the polyethylene terephthalate film.

Sample 22:

as shown in table 5, a photocurable resin composition of sample 22 was prepared in the same manner as in sample 8 except that the amount of the fluorescent agent was changed from 0.001 parts by mass to 0.020 parts by mass, the amount of the styrene-ethylene-propylene-styrene block copolymer (SEPS) of the thermoplastic elastomer (trade name "SEPTON 2063", manufactured by kohlrabi, having a styrene content of 13% by mass) was changed to SIBS (styrene-isobutylene-styrene block copolymer) (trade name "SIBSTAR 102T", manufactured by Kaneka, having a styrene content of 15% by mass), and the amount of the Camphorquinone (CQ) of the first photoinitiator was changed from 0.43 parts by mass to 0.20 parts by mass. The photocurable resin composition of sample 22 was also irradiated with ultraviolet rays in the same manner as in sample 8, and a cured product of sample 22 was formed on the polyimide film and the polyethylene terephthalate film.

Sample 23:

as shown in table 5, a photocurable resin composition of sample 23 was prepared in the same manner as in sample 8, except that the amount of the fluorescent agent added was changed to 0.020 parts by mass, the thermoplastic elastomer was not added, and the amount of phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide (trade name "omniirad 819", produced by igmesesins b.v.) as the photo-radical polymerization initiator was changed from 0.43 parts by mass to 0.50 parts by mass as the second photoinitiator. The photocurable resin composition of sample 23 was also irradiated with ultraviolet rays in the same manner as in sample 8, and a cured product of sample 23 was formed on the polyimide film and the polyethylene terephthalate film.

Samples 24 and 25:

photocurable resin compositions of samples 24 and 25 were prepared in the same manner as in sample 8, except that the amount of Camphorquinone (CQ) added as the first photoinitiator was changed from 0.43 parts by mass to 0.20 parts by mass, the amount of fluorescent agent was changed from 0.001 parts by mass to 0.040 parts by mass, and the amount of lauryl acrylate as the monofunctional aliphatic acrylic monomer and the amount of isobornyl acrylate as the monofunctional alicyclic acrylic monomer were changed as shown in table 5. The photocurable resin compositions of samples 24 and 25 were also irradiated with ultraviolet rays in the same manner as sample 8, and cured products of samples 24 and 25 were formed on the polyimide film and the polyethylene terephthalate film.

Samples 26 to 29:

as shown in Table 6, except that the thermosetting elastomer was changed to a styrene-isobutylene-styrene block copolymer (SIBS) (trade name "SIBSTATAR 103T", manufactured by Kaneka, Inc., having a styrene content of 30 mass%) having a styrene content of 30 mass%, a styrene-ethylene-propylene-styrene block copolymer (SEPS) (trade name "SEPTON 2002", manufactured by Colorado, having a styrene content of 30 mass%) having a styrene content of 30 mass%, and an epoxy-modified styrene-butadiene-styrene block copolymer (SBS) (trade name "AT 501", manufactured by Dassel, having a styrene content of 40 mass%) having a styrene content of 40 mass%, the amount of Camphorquinone (CQ) of the first photoinitiator was changed to 0.20 parts by mass, and the amount of the fluorescent agent was changed to 0.020 parts by mass, respectively, Further, photocurable resin compositions of samples 26 to 29 were prepared in the same manner as in sample 8, except that the amount of lauryl acrylate as the monofunctional aliphatic acrylic monomer and the amount of isobornyl acrylate as the monofunctional alicyclic acrylic monomer were changed as shown in table 6. The photocurable resin compositions of samples 26 to 29 were also irradiated with ultraviolet rays in the same manner as sample 8, and cured products of samples 26 to 29 were formed on the polyimide film and the polyethylene terephthalate film.

Sample 30:

as shown in table 6, a photocurable resin composition of sample 30 was prepared in the same manner as in sample 8 except that the amount of Camphorquinone (CQ) added as the first photoinitiator was changed to 0.20 parts by mass, the amount of the fluorescent agent added was changed to 0.020 parts by mass, and the amount of phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide (trade name "omniirad 819", manufactured by igmesesins b.v.) added as the second photoinitiator was changed to 1.00 parts by mass. The photocurable resin composition of sample 30 was irradiated with ultraviolet rays in the same manner as in sample 8, and a cured product of sample 30 was formed on the polyimide film and the polyethylene terephthalate film.

Sample 31:

a photocurable resin composition of sample 26 was prepared in the same manner as in sample 8, except that as shown in table 7, no fluorescent agent was added and 0.50 parts by mass of benzoyl peroxide (abbreviated as "BPO" in the table) was added instead of the first photoinitiator. The photocurable resin composition of sample 31 was irradiated with ultraviolet rays in the same manner as in sample 8, and a cured product of sample 31 was formed on the polyimide film and the polyethylene terephthalate film.

Samples 32 to 33:

as shown in table 7, photocurable resin compositions of samples 32 to 33 were prepared in the same manner as in sample 8 except that a fluorescent agent was not added, and a combination of 0.50 parts by mass of Benzoyl Peroxide (BPO) as a redox initiator and 0.50 parts by mass of basic tertiary amine 2- (dimethylamino) ethyl methacrylate (abbreviated as "DMAEMA" in the table) as a reducing agent, and a combination of 0.50 parts by mass of Benzoyl Peroxide (BPO) as a redox initiator and 0.50 parts by mass of a photobase generator 1, 2-dicyclohexyl-4, 4, 5, 5, -tetramethylbiguanide n-butyl triphenylborate (product name "WPBG-300", manufactured by fugillmwako pure chemical corporation) as a reducing agent were used instead of the first photoinitiator. The photocurable resin compositions of samples 32 to 33 were irradiated with ultraviolet rays in the same manner as sample 8, and cured products of samples 32 to 33 were formed on the polyimide film and the polyethylene terephthalate film.

The compositions and evaluation results of samples 1 to 33 are shown in tables 1 to 7. The evaluation method is described below.

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

[ Table 5]

[ Table 6]

[ Table 7]

Here, an example of the refractive index value of a cured product of a photocurable component containing a monofunctional (meth) acrylic monomer and the refractive index value of a thermoplastic elastomer measured at a wavelength of 589nm and 23 ℃ is shown below. Further, "a cured product of a photocurable component containing a monofunctional (meth) acrylic monomer, from which the thermoplastic elastomer was removed from sample 3" means a cured product of a photocurable component composed of lauryl acrylate, isobornyl acrylate, and 1, 9-nonanediol diacrylate in table 1.

Refractive index value of cured body of thermoplastic elastomer excluding photocurable component containing monofunctional (meth) acrylic monomer from sample 3: 1.488 (transparent) is used for the film,

refractive index value of cured body containing thermoplastic elastomer (SEPS) of sample 3: 1.488 (transparent) is used for the film,

refractive index value of cured body containing thermoplastic elastomer (SEBS) of sample 2: 1.489 (transparent) and (transparent),

refractive index value of cured body containing thermoplastic elastomer (SIBS) of sample 1: 1.494 (translucent).

Further, the maximum wavelength of the emission spectrum of the fluorescent agent used in the examples was 410nm, and as for the wavelength of the emission intensity having the emission intensity of 10% at the maximum wavelength, 386nm was provided at the short wavelength side and 480nm was provided at the long wavelength side. In addition, the maximum wavelength of the absorption spectrum of the photoinitiator phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide (Omnirad819) is 370nm, the maximum wavelength of 2-dimethylamino-2- (4-methyl-benzyl) -1- (4-morpholin-4-phenyl) -butan-1-one (IrgaCure397) is 330nm, and the maximum wavelength of Camphorquinone (CQ) is 470 nm. Therefore, a maximum wavelength of Camphorquinone (CQ) is within a wavelength range of an emission spectrum of the fluorescent agent, and within a wavelength range having a luminous intensity of 10% or more with respect to a luminous intensity of a maximum wavelength of the emission spectrum. In addition, the maximum wavelength of Camphorquinone (CQ) is a longer wavelength than the maximum wavelength of the emission spectrum of the fluorescent agent.

< various tests and evaluations >

Color before curing:

the color of the photocurable resin compositions before curing of samples 1 to 33 was visually observed.

Evaluation after curing was as follows.

(1) Curing property:

(i) surface curability:

on a polyimide film (Kapton 200H, manufactured by Toho DuPont) having a thickness of 50 μm, at a thickness t₁Coating a photocurable resin composition to a thickness of 200 μm using an LED with a wavelength of 365nm and an illuminance of 200mW/cm²Ultraviolet rays were irradiated for 15 seconds. The surface of the irradiated cured body was measured at 0.98N/cm²(100gf/cm²) After pressing another polyimide film, the following evaluation was performed, assuming that a part of the cured product adhered to the surface of the pressed polyimide film was observed as "transfer", and assuming that almost no transfer was observed visually in the other polyimide film at the time of peeling.

A: there was no transfer.

B: there is a transition.

(ii) Light-shielding portion/PI (immediately following):

as shown in the cross-sectional view of FIG. 1, a polyimide film 10 having a thickness of 50 μm is formed to have a thickness t₁The photocurable composition 20 was applied in a 200 μm manner, and thereon, metal strips 30 (SK material having a thickness of 20 μm) having a width w of 10mm were placed at intervals of 200 μm with spacers therebetween, and a light shielding portion was provided. Then, an LED having a wavelength of 365nm was used, and the illuminance was 200mW/cm in an environment of 23 deg.C²The ultraviolet ray 50 was irradiated for 15 seconds. Under the irradiation of the ultraviolet ray 50, the curing reaction proceeds from the boundary between the light irradiation section and the light shielding section toward the light shielding section in the d direction. Immediately after the irradiation, the metal tape and the spacer 30 were removed, and as shown in fig. 2, after the uncured resin composition was wiped off, the maximum length L of the cured portion of the cured body 40 remaining in the polyimide film 10, which was cured from the boundary between the light irradiation portion and the light shielding portion toward the light shielding portion, was measured. Based on the maximum length L of the cured portion, evaluation was performed according to the following criteria.E or more is acceptable, and C or more is more preferable.

A: the maximum length L of the cured portion is 3.0mm or more.

B: the maximum length L of the cured part is more than 2.5mm and less than 3.0 mm.

C: the maximum length L of the cured part is more than 2.0mm and less than 2.5 mm.

D: the maximum length L of the cured part is 1.5mm or more and less than 2.0 mm.

E: the maximum length L of the cured part is 1.0mm or more and less than 1.5 mm.

F: the maximum length L of the cured part is more than 0.5mm and less than 1.0 mm.

G: the maximum length L of the cured portion is less than 0.5 mm.

(iii) Light-blocking portion/PI (after 1 day):

after the cured product was left at room temperature (about 23 ℃) for 1 day by ultraviolet irradiation in the same manner as described above, the maximum length L of the light-shielding portion of the cured product 40 was confirmed. The evaluation criteria were the same as those of (ii).

(iv) Light shade/PET (immediately following):

the maximum length L of the cured portion immediately after the irradiation with ultraviolet light, which was cured from the boundary between the light irradiation portion and the light shielding portion toward the light shielding portion, was measured by changing the polyimide film having a thickness of 50 μm to a transparent polyester film with a release layer (manufactured by Nipa, trade name "PET 75-HSPX") having a thickness of 100 μm. The evaluation criteria were the same as those of (ii).

(2) Bending resistance:

a photocurable resin composition was applied to a polyimide film having a thickness of 50 μm to a thickness of 200 μm, and an LED having a wavelength of 365nm was used to irradiate light at a rate of 200mW/cm²Ultraviolet rays were irradiated for 15 seconds. Then, the polyimide film was bent at R0 to 180 ° inside to evaluate the bending resistance.

A: has no crack.

B: there was a crack.

(3) The flexibility is as follows:

a photocurable resin composition was applied to a transparent polyester film with a release layer having a thickness of 100 μm to a thickness of 200 μm, and the resultant coating was usedAn LED with a wavelength of 365nm and an illumination intensity of 200mW/cm²Ultraviolet rays were irradiated for 15 seconds. The cured product was peeled from the transparent polyester film, and the cured product having a thickness of 200 μm was cut into a width of 10mm and a length of 20mm, and then the cut product was elongated by 100% to evaluate stretchability. The results of 10-point evaluation were performed.

A: the material is stretched out and then is put into a bag,

b: is easy to break in the middle

(4) Color:

a photocurable resin composition was applied to a release-layer-provided transparent polyester film having a thickness of 100 μm to a thickness of 200 μm, and an LED having a wavelength of 365nm was used under an illuminance of 200mW/cm²Ultraviolet rays were irradiated for 15 seconds. The color of the cured product was visually confirmed.

(5) Light transmittance (%):

coating a photocurable resin composition on a transparent polyester film with a release layer having a thickness of 100 μm, disposing the same transparent polyester film with a release layer on the photocurable resin composition, and then setting the thickness of the resin composition sandwiched between a pair of the transparent polyester films with release layers to 200 μm, using an LED with a wavelength of 365nm, and applying an illumination of 200mW/cm²Ultraviolet rays were irradiated for 15 seconds. The cured product was peeled from the transparent polyester film, and the light transmittance at a wavelength of 300 to 800nm and at 23 ℃ of the cured product having a thickness of 200 μm was measured by an ultraviolet-visible spectrophotometer ("UV-1600 PC" manufactured by Shimadzu corporation). Here, the "400-800 nm average" is a value calculated by adding and averaging the values of transmittances at 400nm to 800nm measured at wavelength intervals of 0.05 nm. The "400-500 nm average" is a value calculated by adding and averaging the transmittance values at 400nm to 500nm measured at wavelength intervals of 0.05nm, and the values of the light transmittance at predetermined wavelengths are shown in the tables.

< analysis of test results >

From the results of samples 1 to 4, even if the second photoinitiator is contained, considering the results of "light-shielding portion/PI (immediately after)" and "light-shielding portion/PI (after 1 day)", as shown in fig. 3, it is found that the photocurable resin composition containing neither the fluorescent agent TPD nor the first photoinitiator has a desired curability in the light-shielding portion CQ in a wavelength range in which the maximum wavelength of the absorption spectrum of the photoinitiator is 10% or more of the emission intensity at the maximum wavelength of the emission spectrum of the fluorescent agent.

From the results of samples 5 and 6, it is found that even if the second photoinitiator and the fluorescent agent are present, when considering the results of "light-shielding portion/PI (immediately after)" and "light-shielding portion/PI (after 1 day)", the curable resin composition containing no first photoinitiator CQ having the maximum wavelength of the absorption spectrum in the range of 400 to 500nm cannot obtain the desired curability in the light-shielding portion.

From the results of sample 7, it is understood that even if the first photoinitiator is contained, the photocurable resin composition containing no second photoinitiator does not satisfy the characteristics as a cured product after curing.

From the results of samples 8 to 10, it is found that when a predetermined amount of fluorescent agent is not contained, the light-shielding part of the photocurable resin composition has poor curability, particularly considering the results of "light-shielding part/PI (immediately after)" and "light-shielding part/PI (after 1 day)".

From the results of samples 11 to 14, it is found that even if the second photoinitiator and the fluorescent agent are present, if the amount of the first photoinitiator CQ having the maximum wavelength of the absorption spectrum of 400 to 500nm is excessively low, the photocurable resin composition cannot obtain the desired curability in the light-shielding portion, particularly considering the results of "light-shielding portion/PI (immediately after)" and "light-shielding portion/PI (after 1 day)".

From the results of samples 15 to 17, it is found that if the fluorescent agent is too much, particularly from the results of "light-shielding portion/PI (immediately after)" and "light-shielding portion/PI (after 1 day)", there is a concern that curability of the light-shielding portion of the photocurable resin composition may be deteriorated.

From the results of samples 9, 11, and 18 to 20, although the tertiary amine which reduces the first photoinitiator to generate radicals was added, no difference was found in curability of the light-shielding portion.

From the results of samples 15, 21, and 30, it is found that the photo radical polymerization initiator of the second photoinitiator, the curing properties of the light-shielding part of the photocurable resin composition of "light-shielding part/PI (immediately after)" and "light-shielding part/PI (after 1 day)" of phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide are more excellent than those of 2-dimethylamino-2- (4-methyl-benzyl) -1- (4-morpholin-4-phenyl) -butan-1-one. Further, it is found that if the amount of the second photoinitiator added is excessively increased, curability may be deteriorated.

From the results of samples 11 and 22 and 23, it is found that when a thermoplastic elastomer having a large difference between the refractive index value of the cured product of the photocurable resin composition and the refractive index value of the cured product of the photocurable component of the resin composition is used, and when the thermoplastic elastomer is not contained at all, the curability of the light-shielding portion of the photocurable resin composition of "light-shielding portion/PI (immediately after)" and "light-shielding portion/PI (after 1 day)" is slightly inferior to that of the thermoplastic elastomer having a styrene content of 20 mass% or less.

From the results of samples 9 and 31 to 33, it is found that even when the thermal radical reaction is applied as in sample 31 and the redox reaction is applied as in samples 32 to 33, the curability of the light-shielding portion of the photocurable resin composition of "light-shielding portion/PI (immediately after)" and "light-shielding portion/PI (after 1 day)" is inferior to that of the case where the fluorescent agent and the first photoinitiator are used.

From the results of samples 1 and 22, it is found that in the case of using a thermoplastic elastomer in which the difference between the refractive index value of the cured product of the photocurable resin composition and the refractive index value of the cured product of the photocurable component of the resin composition is large, the light transmittance of the cured product at the maximum wavelength of the absorption spectrum of the first photoinitiator is low, and as a result, the curability of the light-shielding portion of the photocurable resin composition is slightly deteriorated.

From the results of samples 1 to 4 and samples 11, 22 and 23, it was observed that the cured product of the photocurable component containing the styrene phase, the soft segment phase and the monofunctional (meth) acrylic monomer of the thermoplastic elastomer formed a phase separation structure, and the degree of ease of light transmission and the degree of ease of light entry into the light shielding portion varied depending on the difference in refractive index between the phases.

From the results of samples 15, 24, and 25, it was observed that by changing the blending ratio of the monofunctional aliphatic acrylic monomer and the monofunctional alicyclic acrylic monomer, the difference between the refractive index value of the cured product of the photocurable resin composition and the refractive index value of the cured product of the photocurable component containing the monofunctional (meth) acrylic monomer changes, and thus the light transmittance at a thickness of 200 μm changes. In addition, it is found that when the styrene content of the thermoplastic elastomer is 20 mass% or less, curability of the light-shielding portion on the polyimide film is slightly deteriorated if the blending ratio of the monofunctional alicyclic acrylic monomer is larger than that of the monofunctional aliphatic acrylic monomer.

From the results of samples 11, 22, and 26 to 29, it is found that when the styrene content is 30% by mass, the light transmittance at a thickness of 200 μm of the cured product tends to be lower than when the styrene content of the thermoplastic elastomer is 20% by mass or less. In addition, it is found that when the styrene content of the thermoplastic elastomer is 30 mass% or more, curability of the light-shielding portion on the polyimide film is slightly improved when the blending ratio of the monofunctional alicyclic acrylic monomer is larger than that of the monofunctional aliphatic acrylic monomer.

Description of the reference numerals

10 polyimide film

20 photo-curable resin composition

30 spacer

40 cured body

50 ultraviolet ray.