阅读说明：本技术 铋化合物、固化性组合物及固化物 (Bismuth compound, curable composition, and cured product ) 是由 川崎刚美 百田润二 河村智宏 岸真由美 中谷道人 于 2019-03-14 设计创作，主要内容包括：提供一种具有(甲基)丙烯酰基的磷酸酯与铋键合得到的铋化合物,其毒性少,可溶于单体,可用于光学用途,且可代替铅化合物,以及提供一种通过使(甲基)丙烯酸铋或次水杨酸铋与具有(甲基)丙烯酰基的磷酸酯反应而脱水,制造所述铋化合物的方法。(To provide a bismuth compound obtained by bonding bismuth to a phosphate having a (meth) acryloyl group, which is less toxic, soluble in a monomer, useful for optical applications, and can replace a lead compound, and a method for producing the bismuth compound by reacting bismuth (meth) acrylate or bismuth subsalicylate with a phosphate having a (meth) acryloyl group to dehydrate the reaction product.)

1. A bismuth compound obtained by bonding a phosphate having a (meth) acryloyl group to bismuth.

2. The bismuth compound according to claim 1, wherein the bismuth is further bonded with salicylic acid or (meth) acrylic acid.

3. The bismuth compound according to claim 1 or 2, wherein the phosphate having a (meth) acryloyl group is at least 1 selected from the group consisting of 2- ((meth) acryloyloxy) ethyl dihydrogen phosphate and bis [2- ((meth) acryloyloxy) ethyl ] hydrogen phosphate.

4. A curable composition comprising the bismuth compound according to any one of claims 1 to 3 and another radically polymerizable monomer different from the bismuth compound.

5. The curable composition according to claim 4, wherein the radically polymerizable monomer comprises a styrene compound.

6. A cured product of the curable composition according to claim 4 or 5.

7. A process for producing the bismuth compound according to claim 1, wherein the bismuth (meth) acrylate or bismuth subsalicylate is dehydrated by reacting it with a phosphate having a (meth) acryloyl group.

8. The method of claim 7,

in the production of the bismuth compound, 0.3 to 10 moles of a phosphate ester having (meth) acrylic acid is used per 1 mole of bismuth (meth) acrylate or bismuth subsalicylate.

9. The method according to claim 7 or 8, wherein dehydration is carried out by reacting bismuth (meth) acrylate or bismuth subsalicylate with a phosphate having a (meth) acryloyl group in an aliphatic hydrocarbon solvent or an aromatic solvent.

10. The method according to any one of claims 7 to 9, wherein the dehydration is carried out by reacting bismuth (meth) acrylate or bismuth subsalicylate with the phosphate having a (meth) acryloyl group at a temperature ranging from 50 ℃ to 100 ℃ under reduced pressure.

Technical Field

The present invention relates to a novel bismuth compound, a novel curable composition containing the bismuth compound, and a novel cured product obtained by curing the curable composition.

Background

In recent years, as a material for blocking X-rays, a material using bismuth, rather than a material using lead, which is harmful to the environment, is being studied. Bismuth is an atom suitable for substituting lead, because it has a higher X-ray blocking property than compounds containing barium, antimony, tin, and the like.

For example, as a material using bismuth, a method of directly kneading bismuth or a bismuth compound into a resin material is known (see patent document 1). According to this method, bismuth or a bismuth compound can be compounded into various materials.

However, since this method is direct kneading, bismuth cannot be sufficiently dispersed in the material unless high kneading is performed, and there is room for improvement in this point.

On the other hand, compounds in which an organic group is coordinated to bismuth in order to facilitate dispersion of bismuth in an organic material are known (see patent document 2, non-patent document 1, and non-patent document 2). These methods are more compatible with organic materials and can easily disperse in materials than a method of directly kneading into a resin. In the bismuth compound into which an organic group is introduced by the above-mentioned method, the organic group is an alkyl group, an aryl group (see patent document 2) or a polyethylene glycol chain (see non-patent documents 1 and 2).

In order to more easily and efficiently obtain a material in which bismuth is dispersed in an organic material, for example, a method of mixing a polymerizable radical polymerizable monomer and a bismuth compound to obtain a curable composition and then polymerizing the curable composition to obtain a cured product is preferably employed.

However, since the compounds obtained by the above-mentioned method in which an organic group is coordinated to bismuth do not have a polymerizable group capable of participating in polymerization of a radical polymerizable monomer, when these compounds are used, the curable composition may not be sufficiently polymerized, and a cured product may not be obtained.

When bismuth is dispersed in the obtained cured product using the above-mentioned curable composition containing a radically polymerizable monomer, it is conceivable to use a compound in which a polymerizable group such as (meth) acrylic acid is coordinated to bismuth (see non-patent document 3 and patent document 3). It is known that the solubility of the complex described in non-patent document 3 is improved by coordinating dimethyl sulfoxide (DMSO) in addition to (meth) acrylic acid.

However, the compound described in non-patent document 3 contains DMSO, and is difficult to highly crosslink (polymerize), and there is room for improvement in this point. Further, the polymerization method described in non-patent document 3 merely discloses copolymerization with methyl methacrylate in Dimethylformamide (DMF), and since polymerization is carried out in a solution, it is difficult to contain bismuth in a high concentration in the obtained cured product.

On the other hand, the compound described in patent document 3 has salicylic acid bonded thereto in addition to (meth) acrylic acid, and according to the study by the present inventors, the solubility of the compound with other monomers such as a crosslinking agent is insufficient, and as a result, it is difficult to contain bismuth in a high concentration in a cured product.

Disclosure of Invention

Problems to be solved by the invention

Accordingly, an object of the present invention is to provide a novel bismuth compound having high solubility in organic substances, particularly in radical polymerizable monomers.

Another object of the present invention is to provide a novel bismuth compound which is copolymerizable with the radically polymerizable monomer, and which can highly disperse a bismuth component in a cured product obtained from a curable composition obtained by combining the radically polymerizable monomer with the bismuth compound and can reduce coloring of the cured product.

Another object of the present invention is to provide a method for producing the bismuth compound.

Other objects and advantages of the present invention will be apparent from the following description.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a bismuth compound obtained by bonding a phosphate having a (meth) acryloyl group to bismuth can solve the above-mentioned problems, and have completed the present invention.

Namely, the present invention is that,

(1) a bismuth compound obtained by bonding a phosphate having a (meth) acryloyl group to bismuth.

In addition, the present invention may adopt the following modes.

(2) The bismuth compound according to the above (1), wherein the bismuth further has salicylic acid or (meth) acrylic acid bonded thereto. Namely, a bismuth compound in which a phosphate having a (meth) acryloyl group and salicylic acid or (meth) acrylic acid are bonded to the bismuth.

(3) The bismuth compound according to the (1) or (2), wherein the phosphate having a (meth) acryloyl group is at least 1 selected from 2- ((meth) acryloyloxy) ethyl dihydrogen phosphate and bis [2- ((meth) acryloyloxy) ethyl ] hydrogen phosphate.

(4) A curable composition comprising the bismuth compound according to any one of (1) to (3) and another radically polymerizable monomer different from the bismuth compound.

(5) The curable composition according to (4), wherein the radically polymerizable monomer contains a styrene compound.

(6) A cured product of the curable composition according to (4) or (5).

(7) A method for producing the bismuth compound of (1), characterized in that bismuth (meth) acrylate or bismuth subsalicylate is reacted with a phosphate having a (meth) acryloyl group to dehydrate.

(8) The method according to the above (7), wherein,

in the production of the bismuth compound, 0.3 to 10 moles of a phosphate ester having (meth) acrylic acid is used per 1 mole of bismuth (meth) acrylate or bismuth subsalicylate.

(9) The method according to the item (7) or (8), wherein the dehydration is carried out by reacting bismuth (meth) acrylate or bismuth subsalicylate with a phosphate having a (meth) acryloyl group in an aliphatic hydrocarbon solvent or an aromatic solvent.

(10) The method according to any one of the above (7) to (9), wherein the dehydration is carried out by reacting bismuth (meth) acrylate or bismuth subsalicylate with the phosphate having a (meth) acryloyl group at a temperature range of 50 ℃ to 100 ℃ under reduced pressure.

ADVANTAGEOUS EFFECTS OF INVENTION

The invention provides a bismuth compound which is easily dissolved in an organic substance and has high solubility particularly in a radical polymerizable monomer. Further, the bismuth compound of the present invention can be radically polymerized, and by copolymerizing with a radically polymerizable monomer different from the bismuth compound, a cured product in which the bismuth component is highly dispersed in the obtained cured product can be obtained. Further, the coloring of the cured product can be reduced.

As a result, by using the bismuth compound of the present invention, a cured product which is safe, excellent in X-ray blocking effect and the like, less colored, and high in transmittance can be produced. Therefore, the obtained cured product can be preferably used for medical spectacle lenses and the like.

Drawings

Fig. 1 is a photograph of a bismuth portion of the bismuth compound produced in example 1 observed with a field emission transmission electron microscope (STEM).

Fig. 2 is a photograph of a bismuth portion of the bismuth compound produced in production example 2 observed with a field emission transmission electron microscope (STEM).

Detailed Description

The present invention relates to a bismuth compound in which a phosphate having a (meth) acryloyl group is bonded to bismuth. In the present invention, (meth) acryloyl means methacryloyl and/or acryloyl. In the bismuth compound, a phosphate having a (meth) acryloyl group is bonded to bismuth, and therefore, the bismuth compound exhibits an excellent effect. The bismuth compound is a compound in which a phosphate having a (meth) acryloyl group is bonded to bismuth. The production thereof is preferably carried out by a method in which a phosphate having a (meth) acryloyl group is bonded to bismuth (meth) acrylate or bismuth subsalicylate to obtain the bismuth compound of the present invention.

As the bismuth (meth) acrylate or bismuth subsalicylate, known ones can be used.

First, bismuth (meth) acrylate or bismuth subsalicylate will be described.

Bismuth (meth) acrylate

In the present invention, the bismuth (meth) acrylate includes a compound in which (meth) acrylic acid is bonded to bismuth.

The bismuth (meth) acrylate may contain a compound in which bismuth oxide is combined with (meth) acrylic acid (hereinafter, also simply referred to as "bismuth (meth) acrylate-derived compound") in addition to the compound in which bismuth (meth) acrylate is bonded to (meth) acrylic acid. The compound forming the complex ("compound derived from bismuth (meth) acrylate oxide") is considered to be a compound in which a hydroxyl group formed on the surface of bismuth oxide is bonded by condensation with (meth) acrylic acid, although the structure is not clear. The compound containing bismuth oxide derived from (meth) acrylic acid can be estimated from the production conditions (balance of raw material) or, for example, infrared spectroscopy (IR) and elemental analysis of the product.

Although the compound derived from bismuth (meth) acrylate oxide is very difficult to separate from bismuth (meth) acrylate, the effect of the present invention is not significantly impaired by mixing the compound. Therefore, when the bismuth compound of the present invention is used, the reaction can be carried out without any problem even in a state in which the bismuth (meth) acrylate-derived oxide compound is contained.

The bismuth (meth) acrylate of the present invention is represented by the following formula (1).

Wherein R is a hydrogen atom or a methyl group.

The (methyl) acrylic acid bismuth is (methyl) acrylic acid and bismuth (Bi)³⁺) The bonded compound, bismuth component, can be confirmed by a field emission transmission electron microscope (STEM). That is, the dispersion state of bismuth in the bismuth (meth) acrylate can be observed by a field emission type transmission electron microscope. The conditions for observation by a field emission type transmission electron microscope are shown in the following examples. The bismuth component was observed to be white when measured under the following conditions.

In the present invention, it is considered that the bismuth (meth) acrylate is highly associated with itself or has low solubility in a solvent, and therefore aggregation occurs. Therefore, when the bismuth component is observed by STEM, it is observed as aggregated particles. In the present invention, the longest diameter (hereinafter, sometimes simply referred to as "long diameter") of the aggregated particles is preferably in the range of 0.1 to 30nm, more preferably in the range of 0.1 to 20nm, and still more preferably in the range of 0.5 to 10 nm. That is, in the present invention, the bismuth (meth) acrylate represented by the formula (1) preferably has a long diameter (size) of 0.1 to 30nm as observed by STEM. It is considered that when the long diameter is in the range of 0.1 to 30nm, the aggregated particles also satisfy the same long diameter range in the bismuth compound described later, and the solubility and dispersibility in the radical polymerizable monomer and the like are increased. According to the studies of the present inventors, in the conventional bismuth compound having an organic group introduced therein, the long diameter of the aggregated particles is larger than 30 nm.

Bismuth subsalicylate

In the present invention, the bismuth subsalicylate includes a compound obtained by bonding salicylic acid and bismuth. The bismuth component can be confirmed by the same method as that for the bismuth (meth) acrylate.

The bismuth subsalicylate of the present invention is represented by the following formula (2).

In the present invention, the method for producing the bismuth (meth) acrylate or bismuth subsalicylate is not particularly limited, and the bismuth (meth) acrylate or bismuth subsalicylate can be produced by a known method. In addition, commercially available bismuth (meth) acrylate or bismuth subsalicylate may also be used.

In the following, an example of the production method will be described by taking bismuth (meth) acrylate as an example.

Method for producing bismuth (meth) acrylate

Bismuth (meth) acrylate is produced by mixing bismuth nitrate and (meth) acrylic acid in the presence of an acid, and then neutralizing with a base. In this case, an excess amount of (meth) acrylic acid, for example, 5 to 10 moles of (meth) acrylic acid, is used with respect to 1 mole of bismuth nitrate. The following description will be made in order.

< acid >)

In the production of the bismuth (meth) acrylate of the present invention, examples of the acid used include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and preferred acids are acids. Among them, nitric acid is preferably used for reducing impurities.

These acids may be present in the reaction system in the form of an aqueous solution. Therefore, in the method for producing bismuth (meth) acrylate, water is preferably contained as a solvent. When used in the form of an aqueous solution, a commercially available acid of 0.01 to 16N may be used as the acid.

The amount of the acid used is preferably 0.1 to 1 mol based on 1 mol of bismuth nitrate (for example, in the case of nitric acid, HNO is used₃0.1 to 1 mol).

< bismuth nitrate >

As the bismuth nitrate used for producing the bismuth (meth) acrylate, commercially available bismuth nitrate can be used.

(meth) acrylic acid

As the (meth) acrylic acid used for producing the bismuth (meth) acrylate, commercially available (meth) acrylic acid can be used.

In the present invention, it is preferable that the amount of (meth) acrylic acid used for producing the bismuth (meth) acrylate is 5 to 10 moles based on 1 mole of bismuth nitrate. By using the above amount of (meth) acrylic acid, the bismuth (meth) acrylate having a major axis of 0.1 to 30nm can be easily produced. Further, bismuth (meth) acrylate with less coloration can be obtained. From the viewpoint of productivity and coloration of the obtained bismuth (meth) acrylate, adjustment of the length and diameter of the bismuth component, reaction efficiency, and post-treatment, the amount of (meth) acrylic acid used is more preferably 3 to 20 moles, and still more preferably 5 to 10 moles, based on 1 mole of bismuth nitrate.

< alkali >

In the production of bismuth (meth) acrylate, a base is used to neutralize the (meth) acrylic acid and the acid as raw materials, and a known base can be used. Specific examples thereof include inorganic bases such as alkali metal hydroxides, and organic amines such as amine compounds. Among them, from the viewpoint of productivity, cost, ease of removal in the subsequent steps, and the like, it is preferable to use an inorganic base such as an alkali metal hydroxide, and it is particularly preferable to use sodium hydroxide.

The base is used to neutralize an acid component present in excess after reacting bismuth nitrate with (meth) acrylic acid in the presence of an acid. Therefore, the amount of (meth) acrylic acid used is preferably set to a molar number that is substantially the same as the total molar number of (meth) acrylic acid used in excess (when 3 moles of (meth) acrylic acid are used per 1 mole of bismuth nitrate) and the total molar number of the acids. For example, when 0.5 mol of the acid and 5 mol of the (meth) acrylic acid are used relative to 1 mol of bismuth nitrate, about 5.5 mol of the base is preferably used.

< reaction conditions >

Production conditions other than those described above in the method for producing bismuth (meth) acrylate will be described.

In the method for producing bismuth (meth) acrylate, a method of stirring and mixing an acid, bismuth nitrate and (meth) acrylic acid in a reaction system can be employed. In addition, in order to mix these components under stirring, it is preferable to use a solvent in which the components are mixed.

Examples of the solvent include water, methanol, ethanol, acetone, and THF. Among them, water is preferably used.

The amount of the solvent to be used is preferably such that the respective components can be sufficiently mixed. Among them, from the viewpoint of sufficient mixing and easy removal, the solvent is preferably 3 to 50ml, more preferably 5 to 20ml, and still more preferably 7.5 to 15ml, based on 1g of bismuth nitrate.

As a method for introducing each component into the reaction system, for example, a method in which an acid optionally diluted with the solvent, bismuth nitrate optionally diluted with the solvent, and (meth) acrylic acid optionally diluted with the solvent are added together into the reaction system, followed by stirring and mixing can be employed. Further, a method may be employed in which a solvent is introduced into the reaction system in advance, and then an acid optionally diluted with the solvent, bismuth nitrate optionally diluted with the solvent, and (meth) acrylic acid optionally diluted with the solvent are added together and stirred to mix. Alternatively, 2 components may be introduced into the reaction system in advance, and the other 1 component may be introduced into the reaction system; or a method in which 1 component is introduced into the reaction system in advance, and then the other 2 components are added together or sequentially and mixed with stirring. Among them, the following method is preferably employed in order to reduce coloring of the obtained bismuth (meth) acrylate and improve productivity. First, water is added to bismuth nitrate, which is mixed with nitric acid (if necessary, dilute nitric acid diluted with water is used). To the obtained mixed solution, a polymerization inhibitor such as dibutylhydroxytoluene (BHT), hydroquinone, 4-t-butylcatechol, etc. is added, and finally (meth) acrylic acid is mixed, and this method is preferably employed. Although bismuth nitrate may be directly precipitated as a solid depending on the amount of the solvent used, it is preferable to carry out the reaction at a temperature of about 60 ℃ in a composition ratio of an amount of uniform dissolution so that the reaction can be smoothly carried out.

The temperature (reaction temperature) for stirring the respective components is preferably 30 to 80 ℃ and more preferably 50 to 70 ℃.

The reaction time may be, for example, 20 minutes to 1 hour.

The atmosphere in which the reaction is carried out may be any of atmospheric pressure, reduced pressure and pressurized atmosphere, but from the viewpoint of handling, it is preferable to carry out stirring and mixing (reaction) of the respective components under atmospheric pressure. In addition, the reaction may be carried out in any of an air atmosphere, an inert gas atmosphere, and a dry air atmosphere, and is preferably carried out in an air atmosphere from the viewpoint of handling properties.

By carrying out the reaction under the conditions as described above, the reaction system is once in a uniform state (the solution is in a transparent state). Then, when the reaction is continued by stirring, the suspension in the reaction system starts. The required amount of the base is added to the reaction system for neutralization before the degree of suspension becomes high. At this time, if the temperature rises due to the heat of neutralization and exceeds the boiling point of the solvent, the precipitate generated by the neutralization is foamed, and therefore, it is preferable to carry out the neutralization at such a rate that the temperature rise at the time of the neutralization does not exceed the boiling point.

The treatment after addition of the base is preferably performed by the following method. First, in the obtained reaction solution, a component colored yellow may be observed, and it is considered that a yellow-colored bismuth oxide component is temporarily partially generated. When the yellow-colored component is present, it is preferable that the reaction solution is colorless because the component is redispersed by continuing heating and stirring the reaction solution. This state is preferably used as the end point of the reaction. On the other hand, when the obtained reaction solution is colorless, it can be considered that the reaction solution is at the end point of the reaction.

After the neutralization reaction is completed, when water is used as a solvent, the precipitate generated when heated at 50 to 70 ℃ is filtered, and the precipitate is washed with water at the same temperature on a filter paper. By performing such an operation, the acid and the (meth) acrylic acid used in excess can be removed, and bismuth (meth) acrylate with less coloring and less impurities can be obtained.

Next, the bismuth compound of the present invention will be described.

< bismuth Compound >

The bismuth compound of the present invention includes a compound in which a phosphate having a (meth) acryloyl group (hereinafter, may be simply referred to as "phosphate") is bonded to bismuth. By containing the compound, the solubility, particularly the solubility to a radical polymerizable monomer in a solution state, can be improved. As a result, a cured product obtained by curing the curable composition containing the compound and the radical polymerizable monomer has excellent physical properties and can contain a bismuth component at a high concentration. The bismuth compound can improve the solubility in the radical polymerizable monomer compared with the bismuth (meth) acrylate or bismuth subsalicylate.

The bonding method of bismuth and the phosphate having a (meth) acryloyl group is not particularly limited, and may be either ionic bonding or coordinate bonding.

The bismuth compound may contain a compound in which bismuth oxide is complexed with phosphate and optionally (meth) acrylic acid or salicylic acid (hereinafter, may be simply referred to as "bismuth oxide-derived compound") in addition to the compound in which phosphate is bonded to bismuth. The compound forming the complex (compound derived from bismuth oxide) is believed to be bonded by condensation of hydroxyl groups formed on the surface of bismuth oxide with phosphate and optionally carboxyl groups of (meth) acrylic acid or salicylic acid, although the structure is not clear. It is very difficult to separate the bismuth compound from the bismuth oxide-derived compound. Therefore, when a bismuth oxide-derived compound is produced as a by-product, it is preferably used in a state containing the bismuth oxide-derived compound. When the bismuth oxide-derived compound is produced as a by-product, it is preferable to adjust the production conditions and the like so that the solubility of bismuth (meth) acrylate or bismuth subsalicylate is not lowered. The bismuth oxide-derived compound can be comprehensively judged according to the production conditions thereof or a method such as IR, NMR, X-ray photoelectron spectroscopy (XPS).

As the bismuth compound, for example, the phosphate ester bonded or forming a complex is preferably a phosphate ester having 1 (meth) acryloyl group (mono (di) phosphate), for example, a phosphate ester formed of 2- (methacryloyloxy) ethyl dihydrogen phosphate, 2- (methacryloyloxy) ethyl hydrogen phosphate; or a phosphate ester (phosphodiester) having 2 (meth) acryloyl groups, for example, a phosphate ester formed from bis [2- (methacryloyloxy) ethyl ] hydrogen phosphate. The phosphate may be a phosphate formed only of either one of a phosphate having 1 (meth) acryloyl group and a phosphate having 2 (meth) acryloyl groups, or may be a phosphate formed of both at an arbitrary ratio. In order to obtain a bismuth compound with less coloration or the like, only a phosphate (phosphate monoester) having 1 (meth) acryloyl group may be bonded.

When the phosphate ester is formed of a phosphate ester having 1 (meth) acryloyl group and a phosphate ester having 2 (meth) acryloyl groups, the following ratio is preferable in order to improve the solubility in the radical polymerizable monomer and suppress aggregation of the bismuth component. Specifically, the resin composition preferably comprises 1 mole of a phosphate derived from a phosphate having 1 (meth) acryloyl group and 0.05 to 3 moles of a phosphate derived from a phosphate having 2 (meth) acryloyl groups, more preferably 0.1 to 2 moles of a phosphate derived from a phosphate having 2 (meth) acryloyl groups, and still more preferably 0.15 to 1 mole of a phosphate derived from a phosphate having 2 (meth) acryloyl groups. The advantage of including both a phosphate having 1 (meth) acryloyl group and a phosphate having 2 (meth) acryloyl groups is that bismuth has an appropriate site for bonding between a phosphate having 1 (meth) acryloyl group (phosphate having a 2-valent phosphate group) and a phosphate having 2 (meth) acryloyl group (phosphate having a 1-valent phosphate group), and the appropriate site for bonding is considered to be a result of the phosphate derived from a phosphate having 1 (meth) acryloyl group being present at a ratio of 0.05 to 3 moles relative to 1 mole of the phosphate derived from a phosphate having 2 (meth) acryloyl groups. In addition, the presence of the phosphate having 2 (meth) acryloyl groups at the above ratio tends to decrease the bismuth concentration, but on the other hand, the solubility in the radical polymerizable monomer is improved. As a result, there is also an advantage that the bismuth component can be uniformly present in a high concentration in the cured product.

As long as a phosphate is bonded to the bismuth compound, another compound may be bonded thereto. Specifically, salicylic acid or (meth) acrylic acid may be further bonded. When the phosphate ester and the salicylic acid or (meth) acrylic acid are bonded to bismuth at the same time, the ratio of the phosphate ester to the salicylic acid or (meth) acrylic acid is preferably 0.1 to 10 mol, more preferably 0.1 to 5 mol, further preferably 0.1 to 1 mol, particularly preferably 0.1 to 0.5 mol, based on 1 mol of the phosphate ester, in order to improve the productivity of the bismuth compound itself and to improve the solubility to the radical polymerizable monomer. In the case where 2 or more phosphate esters are present, the above range is based on the total number of moles of the phosphate esters.

The bismuth compound is a compound in which a phosphate having at least a (meth) acryloyl group is bonded to bismuth, and it can be confirmed by a production method thereof, elemental analysis by IR, NMR (nuclear magnetic resonance spectroscopy), energy dispersive X-ray spectroscopy (EDS), or the like that a phosphate having a (meth) acryloyl group is bonded. Further, the number of bonds between salicylic acid or (meth) acrylic acid and each phosphate ester can be known by these methods.

Preferred examples of the bismuth compound of the present invention include those represented by the following formulae (3) to (5).

Wherein R is each independently a hydrogen atom or a methyl group. In the formula (3), m + x + y + z is 3, and x, y, z and m represent the number of moles of a 2- ((meth) acryloyloxy) ethyl phosphate (x) residue, a phenyl-2- ((meth) acryloyloxy) ethyl phosphate (y) residue, a bis [2- ((meth) acryloyloxy) ethyl ] phosphate (z) residue, and a (meth) acrylic acid (m) residue. In the formula (4), 2n + u + v + w is 3, and u, v, w and n represent the number of moles of a 2- ((meth) acryloyloxy) ethyl phosphate (u) residue, a phenyl-2- ((meth) acryloyloxy) ethyl phosphate (v) residue, a bis [2- ((meth) acryloyloxy) ethyl ] phosphate (w) residue and a salicylic acid (n) residue. In the formula (5), 2l + q + r +2s + t is 3, and q, r, s, t and l represent the number of moles of a 2- ((meth) acryloyloxy) ethyl phosphate (q) residue, a benzene-2- ((meth) acryloyloxy) ethyl phosphate (r) residue, a 2- ((meth) acryloyloxy) ethyl phosphate(s) residue, a bis [2- ((meth) acryloyloxy) ethyl ] phosphate (t) residue and a salicylic acid (l) residue.

In the present invention, the bismuth compounds of the formulae (3) to (5) may not be a single compound but may be a mixture of a plurality of compounds. In this case, the number of moles of each residue represents the number of moles of the whole mixture.

In the formula (3), in view of enabling production at a low temperature and obtaining a bismuth compound with little coloration, when m is 0, x: y: and z is 1: 0.05-3: 0.5 to 30, more preferably x: y: and z is 1: 0.1-2: 1 to 20, preferably x: y: and z is 1: 0.15-1: 1.5 to 10. In order to further reduce coloring, m may be 0 and y may be 0.

In the formula (4), when n is 0, x is replaced with u, y is replaced with v, and z is replaced with w.

In the formula (3), when m is other than 0, m is preferably: (x + y + z) is 0.1 to 10: 1, more preferably m: (x + y + z) is 0.1 to 5: 1, more preferably m: (x + y + z) is 0.1 to 1: 1. also in this case, x: y: and z is 1: 0.05-3: 0.5 to 30, more preferably x: y: and z is 1: 0.1-2: 1 to 20, preferably x: y: and z is 1: 0.15-1: 1.5 to 10.

In the formula (4), when n is other than 0, n is preferably: (u + v + w) ═ 1: 0.1-1: 30, more preferably n: (u + v + w) ═ 1: 0.2-1: 20, more preferably n: (u + v + w) ═ 1: 0.3-1: 10, particularly preferably n: (u + v + w) ═ 1: 0.5: 5. also in this case, u: v: w is 1: 20-0.05: 40 to 0.1, more preferably u: v: w is 1: 10-0.1: 20 to 0.2, more preferably u: v: w is 1: 5-0.2: 10 to 0.4.

Among these, a compound in which at least bismuth subsalicylate and 2- ((meth) acryloyloxy) ethyl hydrogen phosphate are bonded is preferably contained. In the formula (5), l is preferred: (q + r + s + t) ═ 1: 0.1 to 30, more preferably l: (q + r + s + t) ═ 1: 0.2 to 20, and preferably l: (q + r + s + t) ═ 1: 0.3 to 10, particularly preferably l: (q + r + s + t) ═ 1: 0.5: 5. also in this case, q: r: s: t is 1: 50-0.1: 20-0.05: 40 to 0.1, more preferably q: r: s: t is 1: 30-0.3: 10-0.1: 20 to 0.2, more preferably q: r: s: t is 1: 20-0.5: 5-0.2: 10 to 0.4.

Of these, those containing at least bismuth subsalicylate and 2- ((meth) acryloyloxy) ethyl dihydrogen phosphate are preferably used in a ratio of 2: 1 bonded compound.

The bismuth compound of the present invention forms granular aggregates due to its high aggregation or low solubility. In this case, the length of the aggregated particles is preferably in the range of 0.1 to 30nm when observed by a field emission transmission electron microscope. It is considered that by setting the long diameter of the aggregated particles to be in the range of 0.1 to 30nm, the solubility to organic substances, particularly radical polymerizable monomers, can be improved, and the dispersibility in the obtained cured product can be improved.

When the length of the aggregated particles exceeds 30nm, the solubility tends to be lowered and the dispersibility in the obtained cured product tends to be lowered. On the other hand, when the length of the aggregated particles is less than 0.1nm, the production is difficult, or a complex in which nearly 3 (meth) acrylic acids and bismuth are bonded is formed, so that the concentration of bismuth is reduced, the solubility in organic substances is reduced, and the dispersion state in the obtained cured product tends to be deteriorated.

In the bismuth compound, the long diameter is preferably 0.5 to 20nm, more preferably 0.5 to 10nm, from the viewpoints of productivity per se, solubility in organic substances, and dispersibility in the obtained cured product.

In the bismuth compound, granular aggregates are formed. The bismuth component in the phosphate ester, and optionally the salicylic acid-or (meth) acrylic acid-bonded bismuth-bonded compound, and optionally the bismuth oxide-and phosphate ester-and optionally the salicylic acid-or (meth) acrylic acid-complex-forming compound (bismuth oxide-derived compound) can be confirmed by field emission transmission electron microscopy (STEM). The observed bismuth component aggregated particles preferably have a major axis diameter in the range of 0.1 to 30 nm.

Next, a preferred method for producing the bismuth compound will be described.

< method for producing bismuth Compound >

In the present invention, the bismuth compound is preferably produced by reacting the bismuth (meth) acrylate or bismuth subsalicylate with a phosphate having a (meth) acryloyl group.

Specifically, the bismuth compound of the present invention is preferably produced by reacting the bismuth (meth) acrylate or bismuth subsalicylate with a phosphate ester having a methacrylic group and dehydrating the reaction product by adding a polymerization inhibitor to an aliphatic hydrocarbon solvent or an aromatic solvent, if necessary.

< a phosphoric acid ester (phosphoric acid ester) having a (meth) acryloyl group; process for producing bismuth compound

As the phosphate having a (meth) acryloyl group, commercially available ones can be used. In addition, the phosphate ester may be a phosphate ester having 1 (meth) acryloyl group, a phosphate ester having 2 (meth) acryloyl groups, and a mixture thereof. Examples of the phosphate having 1 (meth) acryloyl group (hereinafter, may be referred to as "monofunctional phosphate") include 2- (methacryloyloxy) ethyl dihydrogen phosphate and 2- (methacryloyloxy) ethyl hydrogen phosphate. Examples of the phosphate having 2 (meth) acryloyl groups (hereinafter, may be simply referred to as "bifunctional phosphate"), include bis [2- (methacryloyloxy) ethyl ] hydrogen phosphate. Also, naturally, a mixture of these monofunctional phosphate esters and bifunctional phosphate esters may be used in the reaction.

The amount of phosphate to be used may be determined as long as it is ensured that the desired bismuth compound can be obtained. Specifically, the amount of the phosphate is preferably 0.3 to 10 relative to 1 mole of bismuth (meth) acrylate or bismuth subsalicylate.

In the present invention, as the phosphate having a (meth) acryloyl group, a phosphate triester such as diphenyl-2-methacryloyloxyethyl phosphate, phenylbis [2- (methacryloyloxyethyl) ] phosphate, tris [2- (methacryloyloxyethyl) ] phosphate, or the like may be further added in order to improve compatibility with other monomers.

When a phosphoric triester having a phenyl group such as diphenyl-2-methacryloyloxyethyl phosphate or phenylbis [2- (methacryloyloxyethyl) ] phosphate is used, a 1-valent phenylphosphonic acid diester having 1 (meth) acryloyl group in the formulae (3) to (5) can be introduced.

The amount of the phosphoric acid triester to be blended is preferably 0.1 to 20 moles, more preferably 0.2 to 5 moles, based on 1 mole of the phosphate having 1 (meth) acryloyl group and/or the phosphate having 2 (meth) acryloyl groups.

< aliphatic hydrocarbon solvent or aromatic solvent >

In the present invention, it is preferable that the bismuth (meth) acrylate or bismuth subsalicylate and the phosphate ester are stirred and mixed in an aliphatic hydrocarbon solvent or an aromatic solvent to react with each other. In this case, water is generated in the reaction system, and therefore, it is preferable to dehydrate the generated water. In order to easily dehydrate the produced water, it is preferable to use an aliphatic hydrocarbon solvent or an aromatic solvent having a high boiling point, specifically, a boiling point of 100 ℃. An aliphatic hydrocarbon solvent or an aromatic solvent may be used as the mixed solution.

Examples of the aliphatic hydrocarbon solvent or aromatic solvent include hexane, heptane, nonane, decane, undecane, dodecane, xylene, dimethoxybenzene and isomers thereof, benzene, toluene, chlorobenzene, bromobenzene, anisole, petroleum ether, naphtha and benzoin. The amount of the aliphatic hydrocarbon solvent or the aromatic solvent used is not particularly limited as long as the bismuth (meth) acrylate or bismuth subsalicylate and the phosphate ester can be sufficiently mixed. Among these, from the viewpoint of productivity of the bismuth compound, it is preferable to use an aliphatic hydrocarbon solvent or an aromatic solvent in a proportion of 10 to 100ml relative to 1g of bismuth (meth) acrylate or bismuth subsalicylate.

< reaction conditions; process for producing bismuth compound

In the present invention, the method for introducing the bismuth (meth) acrylate, the bismuth subsalicylate, and the phosphate into the reaction system is not particularly limited. A method of adding the bismuth (meth) acrylate or bismuth subsalicylate optionally diluted with the aliphatic hydrocarbon solvent or the aromatic solvent and the phosphate ester optionally diluted with the aliphatic hydrocarbon solvent or the aromatic solvent together into a reaction system and then stirring and mixing them may be employed. Further, a method may be employed in which an aliphatic hydrocarbon solvent or an aromatic solvent is introduced into the reaction system in advance, and then the bismuth (meth) acrylate or bismuth subsalicylate optionally diluted with the aliphatic hydrocarbon solvent or the aromatic solvent and the phosphate ester optionally diluted with the aliphatic hydrocarbon solvent or the aromatic solvent are added together and stirred to mix. In addition, a method of introducing one component into the reaction system in advance, then introducing the other component into the reaction system, and stirring and mixing the components may be employed. Among them, the following method is preferably employed in order to reduce coloration of the obtained bismuth compound and improve productivity. First, bismuth (meth) acrylate or bismuth subsalicylate is uniformly present in an aliphatic hydrocarbon solvent or an aromatic solvent. In this case, it is preferable to crush the cake of bismuth (meth) acrylate or bismuth subsalicylate by an ultrasonic device or the like so that the cake does not exist. Then, it is preferable to adopt a method of adding a phosphate to a cloudy solution in which bismuth (meth) acrylate or bismuth subsalicylate is dispersed, and starting stirring and heating.

The temperature (reaction temperature) for stirring the respective components may be the reflux temperature of the aliphatic hydrocarbon solvent or the aromatic solvent, but in order to further reduce the coloration of the bismuth compound to be obtained, the reaction is preferably carried out at a temperature of 30 to 110 ℃, more preferably at a temperature of 40 to 100 ℃, and still more preferably at a temperature of 45 to 90 ℃.

In addition, when the reaction temperature is 30 to 110 ℃, it is preferable to reduce the pressure of the reaction system in order to remove water (dehydration) generated in the reaction system. The dehydration may be performed while mixing the bismuth (meth) acrylate or bismuth subsalicylate with the phosphate, or may be performed after mixing both. However, from the viewpoint of enhancing the efficiency of the reaction, it is preferable to dehydrate the reaction mixture while mixing the reaction mixture.

The reaction time is not particularly limited, and may be usually 20 minutes to 2 hours.

The reaction is preferably carried out in an air atmosphere from the viewpoint of handling properties, although the reaction may be carried out in an air atmosphere, an inert gas atmosphere, or a dry air atmosphere.

After the reaction under the conditions described above, the obtained bismuth compound is preferably concentrated by distilling off the solvent, and when an insoluble turbid component is present, the insoluble turbid component is separated by filtration or centrifugation. Further, a solvent which is soluble in the reaction solvent used but does not dissolve the bismuth compound is added to the concentrated reaction solution obtained by the treatment, and reprecipitated for purification. When the high boiling point solvent remains, the above-mentioned decantation operation is repeated to replace the solvent. Then, the residual solvent is removed by distillation, and vacuum drying is performed to purify the bismuth compound.

The obtained bismuth compound can be independently cured by polymerization to produce a cured product. Among them, in order to make the obtained cured product more useful, it is preferable to use a curable composition obtained by combining with other radical polymerizable monomers.

< curable composition >

The present invention provides a curable composition containing the bismuth compound and a radically polymerizable monomer other than the bismuth compound (which may be simply referred to as "radically polymerizable monomer").

< radically polymerizable monomer other than bismuth Compound >

In the present invention, as the radical polymerizable monomer, conventionally known monomers can be used. Specific examples thereof include various commercially available monofunctional or polyfunctional acrylic acid, methacrylic acid ester, and vinyl compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, vinylpyridine, vinylpyrrolidone, acrylonitrile, phenyl methacrylate, benzyl methacrylate, and 2-phenoxyethyl methacrylate. Among them, a styrene compound can be used from the viewpoint of solubility of the bismuth compound. Examples of the styrene compound include styrene, methylstyrene and structural isomers thereof, methylstyrene dimer, chlorostyrene, bromostyrene, and divinylbenzene. The radical polymerizable monomers may be used alone or in combination of two or more.

< preferred compounding ratio >

In the curable composition, the blending ratio of the bismuth compound and the radical polymerizable monomer other than the bismuth compound is appropriately determined depending on the application of the cured product to be obtained.

When the bismuth compound is used, from the viewpoint of an X-ray blocking effect, dispersibility, a coloring reduction effect, and the like, it is preferable to use 1 to 500 parts by mass of the radical polymerizable monomer, more preferably 5 to 300 parts by mass, and still more preferably 10 to 200 parts by mass, based on 100 parts by mass of the bismuth compound.

< other compounding agents >

In the curable composition of the present invention, in addition to the bismuth compound and the radically polymerizable monomer, a known compounding agent to be mixed into the radically polymerizable curable composition may be compounded.

Specifically, a radical polymerization initiator, an antioxidant, a mold release agent for improving releasability from a mold, a coloring matter for adjusting the color tone of a cured product, a chain transfer agent for controlling polymerizability, and the like may be blended. These compounding agents may be compounded within a range not to impair the effects of the present invention. The blending agent is preferably blended in an amount of 0 to 30 parts by mass, more preferably 0.01 to 20 parts by mass, and still more preferably 0.02 to 15 parts by mass, based on 100 parts by mass of the total of the bismuth compound and the radical polymerizable monomer.

These curable compositions can be produced by mixing the bismuth compound with a radical polymerizable monomer and optionally various blending agents.

< method for producing cured product >

In the present invention, a known method can be used as a method for obtaining a cured product by curing the curable composition. Specifically, photopolymerization, thermal polymerization, or both polymerization methods can be employed. The preferred polymerization method is determined by the radical polymerization initiator, which is optionally compounded.

< Property of the obtained cured product >

The curable composition of the present invention can give a cured product which contains a bismuth component having a high X-ray-blocking ability, has high transmittance, and is less colored. The cured product obtained from the curable composition of the present invention may have a thickness of, for example, 2mm, a transmittance at a wavelength of 560nm of 80% or more, an X-ray blocking ability equivalent to 0.02mm or more of a lead foil, and a yellowness of 40 or less.

In addition, according to the present invention, the bismuth component contained in the cured product may be 5 to 40 mass% with the total mass of the cured product being 100 mass%.

< use of cured product >

The cured product obtained according to the present invention is visible light-transmissive, but has radiation blocking properties, and therefore can be used for a transparent radiation shielding material.