JP7664198B2 - Vinylnaphthalene composition, vinylnaphthalene cured product and method for producing same - Google Patents

Description

The present invention relates to a vinylnaphthalene composition, a vinylnaphthalene cured product, and a method for producing the same.

Conventionally, vinylnaphthalene-based compositions have been used to form protective films on the surfaces of substrates. Vinylnaphthalene has high polymerizability, and for this reason, vinylnaphthalene-based compositions that aim to inhibit polymerization during storage are known. For example, Patent Document 1 discloses the addition of t-butylcatechol as a polymerization inhibitor to a vinylnaphthalene composition.

Japanese Patent Application Publication No. 9-151142

However, when the present inventors prepared and evaluated vinylnaphthalene compositions containing t-butylcatechol with reference to Patent Document 1, the compositions sometimes had insufficient storage stability during storage, and sometimes had poor curability even when irradiated with active energy rays during use to cure the compositions.
Furthermore, when a vinylnaphthalene composition that does not contain a polymerization inhibitor is applied to a substrate, a uniform film cannot be formed, and the application properties are sometimes poor.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a vinylnaphthalene composition which is excellent in storage stability, coatability and curability.
A further object of the present invention is to provide a vinylnaphthalene-based cured product using the above vinylnaphthalene-based composition and a method for producing the same.

As a result of intensive research, the inventors discovered that the above object can be achieved by adopting the following configuration, and thus completed the present invention.

That is, the present invention provides the following [1] to [4].
[1] Contains 1-vinylnaphthalene and 2-vinylnaphthalene,
A liquid vinylnaphthalene-based composition, in which the content of the 1-vinylnaphthalene is 95 to 51 mass % and the content of the 2-vinylnaphthalene is 5 to 49 mass % in the total content of the 1-vinylnaphthalene and the 2-vinylnaphthalene.
[2] Further containing a photosensitive polymerization initiator,
The vinylnaphthalene composition according to [1], wherein the content of the photosensitive polymerization initiator is 0.5 to 5.0 mass % of the total content.
[3] A vinylnaphthalene-based cured product obtained by curing the vinylnaphthalene-based composition according to [1] or [2].
[4] A method for producing a vinylnaphthalene-based cured product, comprising irradiating the vinylnaphthalene-based composition according to [1] or [2] with active energy rays to cure the liquid vinylnaphthalene-based composition to obtain a vinylnaphthalene-based cured product.

The present invention provides a vinyl naphthalene composition that has excellent storage stability, coatability, and curability.

[Vinyl naphthalene composition]
The vinyl naphthalene composition of the present invention (the composition of the present invention) is
Contains 1-vinylnaphthalene and 2-vinylnaphthalene,
The liquid vinylnaphthalene composition has a 1-vinylnaphthalene content of 95 to 51 mass % and a 2-vinylnaphthalene content of 5 to 49 mass % in the total content of the 1-vinylnaphthalene and the 2-vinylnaphthalene.

The reason why the composition of the present invention has excellent storage stability is believed to be that the coexistence of 1-vinylnaphthalene and 2-vinylnaphthalene in an appropriate ratio makes it possible to suppress an increase in viscosity of the composition due to self-polymerization of vinylnaphthalene during storage.
Conventional compositions mainly contain 2-vinylnaphthalene as a monomer component, which has a highly symmetrical molecular structure and is crystalline, and therefore are likely to undergo self-polymerization of vinylnaphthalene during storage.
On the other hand, in the composition of the present invention, 1-vinylnaphthalene, which has a different symmetry from 2-vinylnaphthalene, is mixed in a larger amount than 2-vinylnaphthalene to lower the symmetry of the entire monomer components, i.e., to reduce the crystallinity of the monomer components, making it difficult to produce a polymer by self-polymerization of the monomer components as described above. Even if a polymer is produced by self-polymerization, the crystallinity of the polymer is low, so that the composition of the present invention can suppress an increase in viscosity even after long-term storage and is considered to have excellent storage stability.
Each component contained in the composition of the present invention will be described below.

<1-Vinylnaphthalene and 2-Vinylnaphthalene>
The composition of the present invention contains 1-vinylnaphthalene and 2-vinylnaphthalene, and therefore has excellent storage stability and curing properties.

《1-Vinylnaphthalene》
1-Vinylnaphthalene (1-VN) is a compound represented by the following formula: 1-Vinylnaphthalene is a liquid at room temperature (20°C) and has a bp of 135-138°C.

2-Vinylnaphthalene
2-Vinylnaphthalene (2-VN) is a compound represented by the following formula: 2-Vinylnaphthalene has an mp of 64-68°C and is a solid at room temperature (20°C).

<1-VN, 2-VN Content>
In the present invention, the content of 1-vinylnaphthalene is 95 to 51 mass % and the content of 2-vinylnaphthalene is 5 to 49 mass % in the total content of 1-vinylnaphthalene and 2-vinylnaphthalene. By having the contents of 1-VN and 2-VN each in the above range, the composition of the present invention has excellent storage stability and coatability.
From the viewpoints of achieving superior effects of the present invention (particularly storage stability) and an excellent balance between storage stability and coatability and/or curability, the content of 1-VN is preferably 85 to 51 mass%, more preferably 75 to 51 mass%, and most preferably 75 to 55 mass% of the total content.
From the viewpoints of achieving superior effects of the present invention (particularly storage stability) and an excellent balance between storage stability and coatability and/or curability, the content of 2-VN is preferably from 15 to 49 mass%, more preferably from 25 to 49 mass%, and most preferably from 25 to 45 mass% of the total content.

<Photosensitive Polymerization Initiator>
The composition of the present invention can be cured, for example, by irradiation with active energy rays, but from the viewpoint of more excellent curability (curing promotion), it is preferable that the composition of the present invention further contains a photosensitive polymerization initiator. In addition, when the composition of the present invention further contains a photosensitive polymerization initiator, it is preferable in that the coating film (film) obtained from the composition of the present invention has high hardness and becomes a cured product with excellent durability.
The photosensitive polymerization initiator that can be further contained in the composition of the present invention is not particularly limited, and examples thereof include generally known photoradical generators and photoacid generators.
Examples of the photoradical generator include 1-hydroxycyclohexyl phenyl ketone and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.
Examples of the photoacid generator include sulfonium salts and iodonium salts, and specific examples include sulfonium salts having phosphorus-based anions.

<Photosensitive polymerization initiator content>
When the composition of the present invention further contains a photosensitive polymerization initiator, the content of the photosensitive polymerization initiator is preferably 0.5 to 5.0 mass % of the total content of 1-vinylnaphthalene and 2-vinylnaphthalene, from the viewpoints of more excellent curability (curing promotion), rapid formation of a vinylnaphthalene-based coating film (film) having high hardness and improved durability, and suppression of bleed-out from the obtained cured product or coloration of the cured product.
Generally, it is preferred that the photosensitive polymerization initiator is added immediately before the vinylnaphthalene composition is cured.

Additives
The composition of the present invention may further contain additives as necessary, within the range that does not impair the properties of the obtained vinyl naphthalene-based cured product.The additives include, for example, polymerizable olefin compounds; crosslinking agents and coupling agents; fillers such as silica and talc; pigments, dyes, inorganic salts, solvents, radical scavengers, pH stabilizers, antistatic agents, release agents, and polymerization inhibitors (viscosity stabilizers).The type and content of additives can be appropriately selected.

Polymerizable olefin compound Polymerizable olefin compound is not particularly limited as long as it is a compound having an ethylenic functional group.Since the vinylnaphthalene-based cured product obtained by curing the vinylnaphthalene-based composition of the present invention can have high heat resistance and high refractive index, when the composition of the present invention further contains a polymerizable olefin compound, it is sufficient to select, as the polymerizable olefin compound, a monomer that does not deteriorate various properties according to the heat-resistant use and transparent optical use of the vinylnaphthalene-based cured product.
Examples of the polymerizable olefin compound include aromatic olefin compounds such as indene, benzofuran, and acenaphthylene; aliphatic olefin compounds; vinyl esters such as acrylate, methacrylate, and thioacrylate; and vinyl ethers such as phenyl vinyl ether and dihydropyran.

<Method for producing the composition of the present invention>
The method for producing the composition of the present invention is not particularly limited, and may be, for example, a method of mixing the above-mentioned components.
When the composition of the present invention further contains a photosensitive polymerization initiator, it may be of either one-component type or two-component type.
When the composition of the present invention is of a two-liquid type, for example, the first liquid contains 1-vinylnaphthalene and 2-vinylnaphthalene, and the second liquid contains a component other than 1-vinylnaphthalene and 2-vinylnaphthalene, such as a photosensitive polymerization initiator. In the above case, one of the preferred embodiments is that the first liquid does not contain a photosensitive polymerization initiator.

<Liquid>
The composition of the present invention is in a liquid state. The term "liquid state" refers to a state in which the viscosity measured under conditions of 20° C. is 400 Pa·s or less. If the viscosity is in this range, a smooth coating film (film) is easily formed during coating treatment (coating step).
From the viewpoint of obtaining superior effects of the present invention (particularly, storage stability and coatability), the viscosity of the composition of the present invention measured under conditions of 20° C. is preferably 2 mPa·s to 400 Pa·s. The above viscosity may be either the viscosity after production of the composition of the present invention (initial viscosity) or the viscosity of the composition of the present invention when it is used.
The composition of the present invention can maintain a liquid state from the time of production of the composition of the present invention until the time of use. When the composition of the present invention is a one-liquid type, the same applies as above.
When the composition of the present invention is a two-part type, it is sufficient that the mixture obtained by mixing the first and second parts is in a liquid state. When the composition of the present invention is a two-part type and the first part contains 1-vinylnaphthalene and 2-vinylnaphthalene, it is sufficient that the first part is in a liquid state. Note that when the composition of the present invention is a two-part type, the second part (for example, the second part containing a photosensitive polymerization initiator) may be a solid.

Storage of the composition of the present invention
The method and conditions for storing the composition of the present invention are not particularly limited. For example, the composition of the present invention is preferably stored at 50° C. or lower.

Method of Using the Composition of the Present Invention
The method of using the composition of the present invention includes, for example, applying the composition of the present invention to a substrate (application step), and then irradiating the composition of the present invention with active energy rays (curing step) to cure the composition of the present invention. The composition of the present invention can be cured by generating active polymerization species upon irradiation with active energy rays, for example.

Coating Step The coating step is a step of coating the composition of the present invention onto a substrate.
The composition used in the coating step is not particularly limited as long as it is the composition of the present invention.
When the composition of the present invention is a one-liquid type, the composition of the present invention may be used as is.
When the composition of the present invention is of a two-liquid type, the first liquid and the second liquid may be mixed together immediately before application.
The substrate used in the coating step is not particularly limited, and examples thereof include glass, silicon, metal, tile, and plastic.
In the coating process, the method of coating the composition of the present invention on the substrate is not particularly limited, and may be a general method. The substrate in the coating process is not particularly limited. The thickness of the coated composition of the present invention may be set within a generally known range, and is usually 0.5 to 500 μm.

When the composition of the present invention further contains a polymerization inhibitor, the polymerization inhibitor may be removed from the composition of the present invention before the composition of the present invention is applied. There are no particular limitations on the method for removing the polymerization inhibitor from the composition of the present invention. For example, distillation and washing may be mentioned. Although the polymerization inhibitor is a recommended additive because it contributes to further improving storage stability, the content of the polymerization inhibitor is preferably selected in the range of 0% by mass or more and less than 0.15% by mass of the total amount of the composition of the present invention from the viewpoint of not interfering with the effects of the present invention (especially curability) and avoiding bleeding out from the obtained cured product.

Curing Step The curing step is a step of curing the composition of the present invention by irradiating the composition of the present invention with active energy rays.
The active energy rays used in the curing step are not particularly limited, and examples thereof include ultraviolet rays and electron beams. The irradiation conditions in the curing step can be selected according to the purpose and object.

When the composition of the present invention further contains a solvent, it is preferable to remove as much of the solvent as possible from the composition of the present invention before irradiating the composition of the present invention with active energy rays. There are no particular limitations on the method for removing the solvent from the composition of the present invention. For example, heating, blowing air, reducing pressure, and drying can be mentioned.

[Vinyl naphthalene-based cured product]
The vinylnaphthalene-based cured product of the present invention (cured product of the present invention) is a vinylnaphthalene-based cured product obtained by curing the vinylnaphthalene composition of the present invention.

The cured product of the present invention is not particularly limited except that it is a cured product of the composition of the present invention.

The method for producing the cured product of the present invention is not particularly limited. For example, a method in which the vinyl naphthalene composition of the present invention is irradiated with active energy rays to cure the vinyl naphthalene composition to obtain a vinyl naphthalene cured product is exemplified as a preferred embodiment. Specifically, for example, a method similar to the curing step in the method for using the composition of the present invention described above can be exemplified. Before irradiating the composition of the present invention with active energy rays, a step similar to the coating step in the method for using the composition of the present invention may be further included.

When the cured product of the present invention is a film, the thickness of the film is not particularly limited, but can be, for example, 0.5 to 500 μm.
The cured product of the present invention is preferably colorless and highly transparent. In addition, the cured product of the present invention may have, for example, high heat resistance and a high refractive index.

Applications of the cured product of the present invention include, for example, coating agents (specifically, coating agents for optical lenses, sensors, liquid crystals, and organic electroluminescence); films for covering substrates such as glass, silicon, metals, tiles, and plastics; adhesives (for example, for bonding different materials); spacers for adjusting the refractive index; and masking materials for microfabrication of electronic materials by optical processing.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below.

<1-Vinylnaphthalene and 2-Vinylnaphthalene>
In this example, 1-vinylnaphthalene (1-VN) used was 1-vinylnaphthalene (purity after purification: 99.5%) obtained by distilling and refining a 95% purity product manufactured by Sigma-Aldrich by vacuum distillation.
In this example, 2-vinylnaphthalene (2-VN) used was a 95% pure product manufactured by Sigma-Aldrich Co., which was purified by recrystallization in a solvent (purity after purification: 97.0%).

Preparation of vinylnaphthalene composition (solution)
The solutions prepared in the following examples correspond to vinylnaphthalene compositions of the present invention.

Example 1
225.0 g of 1-vinylnaphthalene and 25.0 g of 2-vinylnaphthalene were placed in a 300 ml light-shielded glass bottle and mixed for 2 hours using a shaker (Tokyo Rika Kikai MMS-3020) installed in a room with the outside temperature set at 30° C. to obtain a transparent and colorless solution A.

Example 2
200.0 g of 1-vinylnaphthalene and 50.0 g of 2-vinylnaphthalene were placed in a 300 ml light-shielded glass bottle and mixed for 2 hours using a shaker placed in a room with the outside temperature set at 30° C. to obtain a transparent and colorless solution B.

Example 3
162.5 g of 1-vinylnaphthalene and 87.5 g of 2-vinylnaphthalene were placed in a 300 ml light-shielded glass bottle and mixed for 2 hours using a shaker placed in a room with the outside temperature set at 30° C. to obtain a transparent and colorless solution C.

Example 4
127.5 g of 1-vinylnaphthalene and 122.5 g of 2-vinylnaphthalene were placed in a 300 ml light-shielded glass bottle and mixed for 2 hours using a shaker placed in a room with the outside temperature set at 30° C. to obtain a transparent and colorless solution D.

Comparative Example 1
250.0 g of 1-vinylnaphthalene was placed in a 300 ml light-shielded glass bottle and allowed to stand for 2 hours in a room with the outside temperature set at 30° C. to obtain a transparent and colorless solution E.

Comparative Example 2
250.0 g of 1-vinylnaphthalene and 0.25 g of 4-t-butylcatechol (TBC, manufactured by Tokyo Chemical Industry Co., Ltd., polymerization inhibitor) were placed in a 300 ml light-shielded glass bottle, and the mixture was mixed for 2 hours using a shaker installed in a room with the outside temperature set at 30° C., to obtain a transparent and colorless solution F.

Comparative Example 3
250.0 g of 1-vinylnaphthalene and 0.50 g of 4-t-butylcatechol (TBC, manufactured by Tokyo Chemical Industry Co., Ltd., polymerization inhibitor) were placed in a 300 ml light-shielded glass bottle, and the mixture was mixed for 2 hours using a shaker installed in a room with the outside temperature set at 30° C., to obtain a transparent and colorless solution G.

Comparative Example 4
125.0 g of 1-vinylnaphthalene and 125.0 g of 2-vinylnaphthalene were placed in a 300 ml light-shielded glass bottle and mixed for 2 hours using a shaker placed in a room with the outside temperature set at 30° C. to obtain a transparent and colorless solution H.

<evaluation>
The solutions prepared as described above were subjected to the following tests to evaluate various properties. The results are shown in Table 1.

Storage stability
Storage Stability Test 50 g of each solution was placed in a 50 mL light-shielding glass bottle and stored at three different temperatures, namely 20° C., 30° C., and 40° C., for 15 days, and the state of each solution after storage was observed.
In addition, the viscosity (initial viscosity, unit mPa·s or Pa·s) of each solution (initial solution) before being placed in the light-shielding bottle was measured at 20° C. using a DV-III viscometer (manufactured by Brookfield).
Evaluation Criteria When the solution after storage had fluidity and no solid precipitated in the solution after storage, it was judged to have excellent storage stability and was indicated with "◯".
In addition, when the evaluation result of the storage stability was "good", the viscosity of the solution after storage (viscosity after storage) was measured in the same manner as the initial viscosity. The smaller the difference between the initial viscosity and the viscosity after storage, the better the storage stability.
On the other hand, when the solution after storage lost its fluidity or when a solid precipitated in the solution after storage, this was judged to have poor storage stability and was indicated by "X."
The above evaluation of storage stability can correspond to evaluation of the storage stability of the entire composition of the present invention.
Furthermore, when the composition of the present invention is a two-part type and the first part contains 1-vinylnaphthalene and 2-vinylnaphthalene, the evaluation of storage stability can correspond to the evaluation of storage stability of the first part. In the present invention, when the composition of the present invention is of the above two-part type, the evaluation of storage stability (i.e., the evaluation of storage stability of the first part) is used to evaluate the storage stability of the entire composition of the present invention.

<Coatability>
Coating property test Using each solution that was evaluated as having a storage stability of "good" after storage for 15 days under a condition of 40°C in the storage stability test, 1.0 g of each solution after the storage stability test was placed on a glass plate (slide glass S9112, manufactured by Matsunami Glass Industry Co., Ltd.), and a film having a thickness of approximately 50 μm was formed using a doctor blade (manufactured by Yasuda Seiki Seisakusho Co., Ltd., 2 mil).
Evaluation Criteria When the formed film was smooth, it was judged to have excellent coatability and was marked with "◯".
On the other hand, when a smooth film was not obtained, the coating property was judged to be poor and was indicated by "X".
In addition, the solutions with the storage stability (40°C) evaluation result of "x" were not applicable to coating in the first place, so the coating property test was not performed on the solutions. The above cases are indicated by "-".

<Curing property>
Curability test...coating process In the storage stability test, 10.0 g of each solution that had been evaluated as having a storage stability of "good" after storage for 15 days at 40°C was used to check the fluidity as follows.
To 10.0 g of each solution, 0.2 g of photosensitive polymerization initiator CPI-210S (manufactured by San-Apro Co., Ltd.) was added (2% by mass based on the total content of 1-VN and 2-VN), and after confirming dissolution of the photosensitive polymerization initiator in the solution, the solution was placed on a glass plate (slide glass S9112 manufactured by Matsunami Glass Industry Co., Ltd.), and a film of about 50 μm in thickness was formed using a doctor blade (manufactured by Yasuda Seiki Seisakusho Co., Ltd., 2 mil) to obtain a test panel. The coatability of the mixture after dissolving the photosensitive polymerization initiator in each solution was confirmed by whether or not the film formed as described above was smooth.
Curing Step Each of the obtained test panels was exposed to ultraviolet light for 20 seconds using a UV irradiator equipped with a high-pressure mercury lamp (Ushio Inc., UniCure System UVC-1212) to cure the film (solution).
Evaluation Criteria The film after the curing step was touched with a finger, and the curability was evaluated according to the following criteria.
When the film was touched with a finger, if the surface of the film had lost its tackiness (stickiness), it was judged to have excellent curability and was marked with "O".
On the other hand, if the film did not harden and remained liquid, or if a tacky (sticky) feeling remained on the surface of the film, it was judged to have poor hardening properties and was marked with "X".
In addition, the solutions with the evaluation result of storage stability (40°C) of "x" were not able to be used for coating in the first place, so the curing test was not performed on the above solutions. The above cases are indicated by "-".

As shown in Table 1 above, the vinylnaphthalene compositions (solutions) of Examples 1 to 4 were all excellent in terms of storage stability, coatability and curability.
The films formed in the coating process of the curing tests of Examples 1 to 4 were all smooth, and therefore the vinyl naphthalene compositions of Examples 1 to 4 had excellent coatability even when they further contained a photosensitive polymerization initiator.
Moreover, the vinylnaphthalene-based cured products (films after the curing step) obtained by curing the vinylnaphthalene-based compositions of Examples 1 to 4 were all transparent.

In contrast, Comparative Examples 1 and 2, which did not contain 2-vinylnaphthalene, had insufficient storage stability.
Comparative Example 3, which did not contain 2-vinylnaphthalene but contained TBC as a polymerization inhibitor, did not exhibit sufficient curability.
Comparative Example 4, in which the contents of 1-vinylnaphthalene and 2-vinylnaphthalene were outside the prescribed range, had insufficient coatability and curability.

Claims (4)

Contains 1-vinylnaphthalene and 2-vinylnaphthalene,
A liquid vinylnaphthalene-based composition, in which the content of the 1-vinylnaphthalene is 95 to 51 mass % and the content of the 2-vinylnaphthalene is 5 to 49 mass % in the total content of the 1-vinylnaphthalene and the 2-vinylnaphthalene. Further containing a photosensitive polymerization initiator,
The vinylnaphthalene composition according to claim 1, wherein the content of the photosensitive polymerization initiator is 0.5 to 5.0 mass % of the total content. A vinylnaphthalene-based cured product obtained by curing the vinylnaphthalene-based composition according to claim 1 or 2. A method for producing a vinylnaphthalene-based cured product, comprising irradiating the vinylnaphthalene-based composition according to claim 1 or 2 with active energy rays to cure the liquid vinylnaphthalene-based composition and obtain a vinylnaphthalene-based cured product.