RU2791556C2 - Bismuth compound, curable composition and hardened product - Google Patents

Abstract

FIELD: chemistry.
SUBSTANCE: bismuth compound for obtaining a hardened product, in which a phosphoric acid ester containing a (meth)acrylic group is bonded to bismuth. The phosphoric acid ester is at least one compound selected from the group consisting of 2-((meth)acryloyloxy)ethyl dihydrophosphate, bis[2-((meth)acryloyloxy)ethyl]hydrophosphate, and phenyl-2-((meth)acryloyloxy)ethyl phosphate. A bismuth compound is obtained by a reaction between bismuth (meth)acrylate or bismuth subsalicylate and a phosphoric acid ester containing (meth)acrylic group(s) to effect dehydration. A curable composition and a hardened product are also claimed.

EFFECT: bismuth compound has high solubility in organic material, especially the radical polymerizable monomer, and can achieve a high degree of dispersion of the bismuth component in the cured product obtained from the curable composition containing the radical polymerizable monomer, and can also reduce the coloration of the hardened product.

8 cl, 2 dwg, 1 tbl, 12 ex

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001] The present invention relates to a new bismuth compound, a new curable composition containing a bismuth compound, and a new cured product obtained by curing the curable composition.

BACKGROUND OF THE INVENTION

[0002] Research is currently underway on a material containing bismuth, rather than a material containing environmentally harmful lead, as an X-ray shielding material. Bismuth is an atom that exhibits high X-ray shielding performance compared to compounds containing barium, antimony and tin, and is therefore suitable for use as a substitute for lead.

For example, with respect to a material containing bismuth, a method of directly mixing bismuth or compounding bismuth with a resin material is known (refer to Patent Document 1). According to this method, bismuth or a bismuth compound can be mixed into various materials.

However, there is room for improvement in this method, since this method uses direct mixing, thus making it impossible to completely disperse the bismuth unless it is mixed perfectly.

[0003] Meanwhile, a compound obtained by coordinating an organic group to bismuth, which facilitates dispersion of bismuth in an organic material, is known (refer to Patent Document 2, Non-Patent Document 1 and Non-Patent Document 2). According to these methods, bismuth becomes compatible with the organic material, whereby the bismuth is easily dispersed in the material, compared to the method in which bismuth is directly mixed with the resin. In the bismuth compound to which an organic group has been introduced using the above method, the organic group is an alkyl group or an aryl group (refer to Patent Document 2) or a polyethylene glycol chain (refer to Non-Patent Documents 1 and 2).

In order to obtain a material containing bismuth more easily and efficiently dispersed in an organic material, preferably, for example, a method is used in which a curable composition is obtained by mixing a radically polymerizable monomer with a bismuth compound, which is polymerized to obtain a cured product.

However, since the compound obtained by coordinating an organic group to bismuth using the aforementioned method does not contain a polymerizable group that can be involved in the polymerization of the radical polymerizable monomer, when using this compound, the curable composition is not completely polymerized, and the cured product cannot be received.

[0004] When it is necessary to disperse bismuth in a cured product obtained by using the above curable composition containing a radical polymerizable monomer, one can imagine using a compound obtained by coordinating to bismuth a polymerizable group such as (meth)acrylic acid, (refer to non-patent document 3 and patent document 3). As is known, the complex described in Non-Patent Document 3 has improved solubility because, in addition to (meth)acrylic acid, dimethyl sulfoxide (DMSO) is also coordinated.

However, there is room for improvement in the compound of Non-Patent Document 3 because the compound includes DMSO, thereby making it difficult to achieve a high degree of crosslinking (polymerization) of the compound. Further, in the polymerization method disclosed in Non-Patent Document 3, only copolymerization with methyl methacrylate in dimethylformamide (DMF) is disclosed. Due to the solution polymerization, the incorporation of bismuth into the resulting cured product at a high concentration is difficult.

Meanwhile, in the compound of Patent Document 3, not only (meth)acrylic acid but also salicylic acid is bound, and it was determined from the studies carried out by the present inventors that the compound is unsatisfactory in terms of solubility in yet another monomer, such as a crosslinker, resulting in difficulty incorporating bismuth into a high concentration cured product.

PRIOR ART

Patent Documents

[0005]

Patent Document 1: JP-A 2001-83288

Patent Document 2: JP-A 10-512877

Patent Document 3: JP-A 2017-516991

Non-Patent Documents

[0006]

Non-Patent Document 1: Materials Chemistry and Physics, Vol. 99, 174-180 (2006)

Non-Patent Document 2: American Journal of Engineering Research, Vol. 3, 162-165 (2014)

Non-Patent Document 3: Chemical Communications, Vol. 47, 6353-6355 (2011)

DISCLOSURE OF THE INVENTION

THE PROBLEM SOLVED IN THE INVENTION

[0007] Therefore, one object of the present invention is to provide a novel bismuth compound having high solubility in organic material, especially a radical polymerizable monomer.

Yet another object of the present invention is to provide a novel bismuth compound that is copolymerizable with a radical polymerizable monomer, can achieve a high degree of dispersion of the bismuth component in a cured product obtained from a curable composition containing a radical polymerizable monomer, and can reduce coloration of the cured product. .

Yet another object of the present invention is to provide a method for the production of the aforementioned bismuth compound.

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

REMEDIES

[0008] The present inventors have made intensive studies to solve the above problem, and found a way to solve the above problem by using a bismuth compound in which a phosphoric acid ester containing (meth)acrylic group(s) is bonded to bismuth. The present invention has been made on the basis of this discovery.

[0009] That is, the present invention is as follows.

(1) A bismuth compound in which a phosphoric acid ester containing (meth)acrylic group(s) is bonded to bismuth.

The present invention may take the following forms.

(2) The bismuth compound at the above position (1), wherein bismuth is further bonded with salicylic acid or (meth)acrylic acid. That is, it is a bismuth compound in which a phosphoric acid ester containing (meth)acrylic group(s) and salicylic acid or (meth)acrylic acid are bound to bismuth.

(3) The bismuth compound at the above positions (1) or (2), wherein the phosphoric acid ester containing (meth)acrylic group(s) is at least one compound selected from 2-((meth) acryloyloxy)ethyl dihydrogen phosphate; and bis[2-((meth)acryloyloxy)ethyl]hydrogen phosphate.

(4) A curable composition containing a bismuth compound from any one of the above (1) to (3) and a radically polymerizable monomer other than a bismuth compound.

(5) The curable composition at the aforementioned (4), wherein the radical polymerizable monomer comprises a styrenic compound.

[0010]

(6) The cured product of the curable composition of the above items (4) or (5).

(7) A method for producing a bismuth compound of the above (1) by reacting bismuth (meth)acrylate or bismuth subsalicylate and a phosphoric acid ester containing (meth)acrylic group(s) and performing dehydration.

(8) The method in the above (7), wherein the production of the above-mentioned bismuth compound uses a phosphoric acid ester including (meth)acrylic acid in an amount of 0.3 to 10 mol based on 1 mol of (meth)acrylate bismuth or bismuth subsalicylate.

(9) The method at the above (7) or (8) wherein bismuth (meth)acrylate or bismuth subsalicylate is reacted with a phosphoric acid ester containing (meth)acrylic group(s) in an aliphatic hydrocarbon solvent or an aromatic solvent and carry out dehydration.

(10) The method in any one of the above (7) to (9), wherein bismuth (meth)acrylate or bismuth subsalicylate is reacted with a phosphoric acid ester containing (meth)acrylic group(s) under reduced pressure at a temperature in the range from 50 to 100°C and carry out dehydration.

THE EFFECT OF THE INVENTION

[0011] The present invention provides a bismuth compound that has a high solubility in organic material, especially a radical polymerizable monomer. In addition, the bismuth compound of the present invention is a radical polymerizable, and when it is copolymerized with a radical polymerizable monomer other than a bismuth compound, a cured product containing a bismuth component highly dispersed therein can be obtained. In addition, the bismuth compound can suppress the coloration of the cured product.

As a result, by using the bismuth compound of the present invention, a cured product which is safe, exhibits an excellent X-ray shielding effect, is rarely colored, and has high transmission can be produced. Therefore, the resulting cured product can advantageously be used in spectacle lenses for medical use.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a field emission scanning transmission electron microscope (STEM) photograph of the bismuth component of the bismuth compound produced in Example 1.

Fig. 2 is a field emission scanning transmission electron microscope (STEM) photograph of the bismuth component of the bismuth compound produced in Example 2.

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] The present invention relates to a bismuth compound in which a phosphoric acid ester containing (meth)acrylic group(s) is bonded to bismuth. In the present invention, the term "(meth)acrylic" refers to the terms "methacrylic" and/or "acrylic". The bismuth compound exhibits an excellent effect because what binds to bismuth is a phosphoric acid ester containing (meth)acrylic group(s). In a bismuth compound, a phosphoric acid ester containing (meth)acrylic group(s) is bound to bismuth. With respect to its production, a method for producing a bismuth compound of the present invention by coupling a phosphoric acid ester containing (meth)acrylic group(s) with bismuth (meth)acrylate or bismuth subsalicylate is preferred.

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

First, a description is given of bismuth (meth)acrylate or bismuth subsalicylate.

[0014] <(meth)bismuth acrylate>

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

Bismuth (meth)acrylate, in addition to a compound in which (meth)acrylic acid binds to bismuth, may include a compound in which bismuth oxide and (meth)acrylic acid are composited (simply referred to hereinafter as "a compound derived from (meth) )bismuth oxide acrylate"). Although the structure of the compound forming this composite (“a compound derived from bismuth oxide (meth)acrylate”) is unknown, it is thought to be a compound in which the hydroxyl group formed on the surface of bismuth oxide and (meth ) acrylic acid. Whether or not a compound produced from bismuth oxide (meth)acrylate is contained can be assessed based on the manufacturing conditions (balance of feedstock materials) for the compound or by using infrared spectroscopy (IR) or elemental analysis for the product.

Although it is extremely difficult to separate this compound produced from bismuth oxide (meth)acrylate from bismuth (meth)acrylate, the effect of the present invention is not greatly impaired by the presence of this compound. Therefore, when it is necessary to obtain a bismuth compound of the present invention for the case of containing a compound produced from bismuth oxide (meth)acrylate, there is no problem with the reaction as such.

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

[0015] [formula 1]

(1)

(1)

[0016] In the above formula, R represents a hydrogen atom or a methyl group.

Bismuth (meth)acrylate is a compound in which (meth)acrylic acid binds to bismuth (Bi ^{3 +} ), and the bismuth component can be confirmed using a field emission scanning transmission electron microscope (STEM). That is, the dispersion state of bismuth in bismuth (meth)acrylate can be observed using a field emission scanning transmission electron microscope. The observation conditions using a field emission scanning transmission electron microscope are those that will be demonstrated in the examples below. When measured under the following conditions, the bismuth component is observed with a white color.

[0017] As considered in the present invention, bismuth (meth)acrylate agglomerates due to its high associative properties or low solvent solubility. Therefore, when observing the bismuth component using the STEM method, it is observed in the form of an agglomerated particle. In the present invention, the largest diameter (which hereinafter may simply be referred to as "long diameter") of the agglomerated particle is preferably in the range of 0.1 to 30 nm, more preferably 0.1 to 20 nm, much more preferably 0. 5 to 10 nm. That is, in the present invention, the bismuth (meth)acrylate represented by the above formula (1) preferably has a long diameter (size) of the agglomerated particle observed using the STEM method in the range of 0.1 to 30 nm. As it is considered, when the long diameter is within the range of 0.1 to 30 nm, even in the bismuth compound to be described hereinafter, the agglomerated particle satisfies the same long diameter range, and accordingly, the solubility and dispersibility in the radical polymerizable monomer become high. According to studies carried out by the present inventors, a prior art bismuth compound into which an organic group has been introduced becomes an agglomerated particle having a long diameter of more than 30 nm.

[0018] <bismuth subsalicylate>

In the present invention, bismuth subsalicylate includes a compound in which salicylic acid binds to bismuth. The bismuth component can be confirmed using the same method as the above-mentioned bismuth (meth)acrylate.

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

[0019]

[formula 2]

(2)

(2)

[0020] Although there are no specific restrictions imposed in the present invention on the production method of bismuth (meth)acrylate or bismuth subsalicylate, they can be produced using known methods. Bismuth (meth)acrylate or bismuth subsalicylate available commercially can be used.

Taking bismuth (meth)acrylate as an example, one example of a method for it is described below.

[0021] <process for producing bismuth (meth)acrylate>

Bismuth (meth)acrylate is produced by mixing bismuth nitrate and (meth)acrylic acid together in the presence of an acid and neutralizing the resulting mixture using a base. Currently, an excess is used, for example in the range of 5 to 10 moles of (meth)acrylic acid, based on 1 mole of bismuth nitrate. The following is a description of each component.

[0022] <acid>

Preferred examples of the acid used to produce the bismuth (meth)acrylate of the present invention include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid. Among these, nitric acid is particularly preferably used to reduce the amount of impurities.

The acid may be present in the reaction system in the form of an aqueous solution. Therefore, in the process for producing bismuth (meth)acrylate, water is preferably used as a solvent. When using an acid in the form of an aqueous solution, a commercially available aqueous acid solution with a concentration ranging from 0.01N to 16N can be used as the acid.

The amount of acid is preferably in the range of 0.1 to 1 mol per 1 mol of bismuth nitrate (for example, in the case of nitric acid, 0.1 to 1 mol of HNO ₃ ).

[0023] <bismuth nitrate>

As the bismuth nitrate used for the production of bismuth (meth)acrylate, a commercially available product can be used.

[0024] <(meth)acrylic acid>

As the (meth)acrylic acid used for the production of bismuth (meth)acrylate, a commercially available product can be used.

For the production of the aforementioned bismuth (meth)acrylate in the present invention, the amount of (meth)acrylic acid is preferably in the range of 5 to 10 mol per 1 mol of bismuth nitrate. By using (meth)acrylic acid in this amount, the above-mentioned bismuth (meth)acrylate having a long diameter of the bismuth component in the range of 0.1 to 30 nm can be easily produced. Thus, bismuth (meth)acrylate, which is rarely colored, can be obtained. From the viewpoints of productivity, coloring, controlled maintenance of the long diameter of the bismuth component, reaction efficiency, and post-treatment of the resulting bismuth (meth)acrylate, the amount of (meth)acrylic acid is preferably in the range of 3 to 20 mol, more preferably 5 to 10 mol, with per 1 mole of bismuth nitrate.

[0025] <base>

In the production of bismuth (meth)acrylate, a base is used to neutralize the aforementioned (meth)acrylic acid as a raw material and the aforementioned acid, and known bases can be used. Examples of the base include inorganic bases such as alkali metal hydroxides and organic amines such as amine compounds. Among these, inorganic bases such as alkali metal hydroxides are preferably used, and from the viewpoints of productivity, cost and ease of removal in the downstream process, sodium hydroxide is particularly preferably used.

The base is used to neutralize the acid component present in excess after the reaction of bismuth nitrate with (meth)acrylic acid in the presence of acid. Therefore, the amount of base is preferably set at almost the same number of moles as the total number of moles of (meth)acrylic acid that is used in excess (using 3 moles of (meth)acrylic acid per 1 mole of bismuth nitrate), and the aforementioned acid. For example, when using 0.5 mol of acid and 5 mol of (meth)acrylic acid, based on 1 mol of bismuth nitrate, almost 5.5 mol of base is preferably used.

[0026] <reaction conditions>

A description is given of production conditions other than the above-mentioned conditions in a process for the production of bismuth (meth)acrylate.

In the process for producing bismuth (meth)acrylate, an acid, bismuth nitrate and (meth)acrylic acid are mixed together with stirring in a reaction system. To mix these components with each other with stirring, it is preferable to use a solvent to mix these components with each other in it.

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

The solvent is preferably used in an amount which allows complete mixing of all components with each other. Considering complete mixing and ease of removal, the amount of solvent is preferably in the range of 3 to 50 ml, more preferably 5 to 20 ml, much more preferably 7.5 to 15 ml, based on 1 g of bismuth nitrate.

[0027] To introduce all components into the reaction system, for example, a method can be used in which an acid, diluted as needed with the above solvent, bismuth nitrate, diluted as needed the aforementioned solvent, and (meth)acrylic acid, as necessary, diluted with the aforementioned solvent. A method can also be used in which a solvent is introduced into the reaction system in advance, an acid diluted with the aforementioned solvent as necessary, bismuth nitrate diluted with the aforementioned solvent as necessary, and are jointly added to the interior of the reaction system and mixed with each other with stirring. (meth)acrylic acid, diluted as needed with the solvent mentioned above. In addition, a method can be used in which two components are introduced into the reaction system in advance and another one component is introduced into the reaction system, or one component is introduced into the reaction system in advance and the other two components are added and mixed with the above-mentioned component together or sequentially with stirring. Among them, the following method is preferably used to reduce the coloration of the obtained bismuth (meth)acrylate and improve the productivity. First, a mixture of water and bismuth nitrate and nitric acid are mixed with each other (nitric acid diluted with water is used as needed). To the resulting mixed solution, a polymerization inhibitor such as dibutylhydroxytoluene (BHT), hydroquinone or 4-tert-butyl pyrocatechol is added, and finally (meth)acrylic acid is admixed. While it is possible to retain bismuth nitrate in the solid state as a precipitate according to the amount of solvent used in the reaction for a ratio between the components in the composition that ensures homogeneous dissolution of all components at a temperature of 60°C, the reaction advantageously proceeds smoothly.

[0028] The temperature for mixing the components (reaction temperature), for example, is preferably in the range of 30 to 80°C, more preferably 50 to 70°C.

The reaction time in the General case, for example, is in the range from 20 minutes to 1 hour.

Although the reaction atmosphere may be an atmosphere at atmospheric pressure, reduced pressure, or elevated pressure, in view of the manufacturability, stirring and mixing (reaction mixture) of the components is preferably carried out at atmospheric pressure. The reaction can be carried out in an atmosphere of air, an inert gas atmosphere, or an atmosphere of dried air, preferably an atmosphere of air, taking into account the manufacturability.

[0029] As a result of carrying out the reaction under the above conditions, the interior of the reaction system becomes homogeneous (the solution becomes transparent). After that, with continued stirring of the reaction mixture, the solution in the reaction system begins to turn into a suspension. To achieve a high degree of suspension in the interior of the reaction system for neutralization add the desired amount of the aforementioned base. At this point, when the temperature rises and exceeds the boiling point of the solvent, under the influence of the heat of neutralization, the precipitate produced as a result of neutralization foams. Therefore, it is desirable to carry out the neutralization at a rate at which the temperature increase during the neutralization does not exceed the boiling point.

As the treatment after adding the base, the following method is preferably used. In the resulting reaction solution, a yellow colored component can be observed, which appears to be a partly produced yellow colored bismuth oxide component. When this yellow dye component is present, the reaction solution is preferably kept heated and stirred, whereby the component is redispersed to form a colorless reaction solution. This state, if desired, is considered as the end of the reaction. In the absence of color in the resulting reaction solution, this can be considered as the completion of the reaction.

[0030] After completion of the neutralization reaction using water as a solvent, the precipitate generated during heating in the range of 50 to 70°C is filtered and purified on filter paper using water having the same temperature. As a result of this operation, acid and excess used (meth)acrylic acid can be removed, thereby making it possible to obtain bismuth (meth)acrylate, which is rarely colored and contains few impurities.

The following is a description of the bismuth compound of the present invention.

[0031] <bismuth compound>

The bismuth compound of the present invention includes a compound in which a phosphoric acid ester containing (meth)acrylic group(s) (simply referred to hereinafter as "phosphoric acid ester") is bonded to bismuth. With the content of this compound, the solubility is improved, in particular the solubility in the radical polymerizable monomer, in the form of a solution. As a result, a cured product obtained by curing a curable composition containing this compound and a radical polymerizable monomer can have excellent physical properties and contain a highly concentrated bismuth component. This bismuth compound may have greater solubility in the radical polymerizable monomer than the aforementioned bismuth (meth)acrylate and bismuth subsalicylate.

The bond form between bismuth and a phosphoric acid ester containing (meth)acrylic group(s) is not particularly limited, and may be an ionic bond or a coordination bond.

[0032] A bismuth compound, in addition to a compound in which a phosphoric acid ester is bonded to bismuth, may include a compound in which a bismuth oxide composite is formed with a phosphoric acid ester and optionally (meth)acrylic acid or salicylic acid, (simply referred to below as in this document, "a compound derived from bismuth oxide"). Although the structure of this compound forming a composite (compound produced from bismuth oxide) is not known, it is believed that the hydroxyl group formed on the surface of bismuth oxide and the carboxyl group of a phosphoric acid ester are bound to each other by condensation, and optionally (meth ) acrylic acid or salicylic acid. The separation of this bismuth oxide-derived compound from the bismuth compound is very difficult. Therefore, in the production of a compound produced from bismuth oxide, it is preferable to use a bismuth compound as a by-product while it contains a compound produced from bismuth oxide. When producing a compound produced from bismuth oxide as a by-product, it is desirable to control the amount of the compound in a range that does not reduce the solubility of bismuth (meth)acrylate or bismuth subsalicylate by adjusting the production conditions. Whether or not a compound produced from bismuth oxide is contained can be judged exhaustively by production conditions or by using IR, NMR, or X-ray photoelectron spectroscopic analysis (XPS) techniques.

[0033] With regard to the bismuth compound, the phosphoric acid ester that binds or forms a composite is preferably formed from a phosphoric ester containing one (meth)acrylic group (mono(di)ester of phosphoric acid) such as 2 -(methacryloyloxy)ethyl dihydrogen phosphate or phenyl-2-(methacryloyloxy)ethyl hydrogen phosphate, or a phosphate ester containing two (meth)acrylic groups (phosphoric acid diester) such as bis[2-(methacryloyloxy)ethyl]hydrogen phosphate. The phosphoric acid ester can be formed from only one of a phosphoric acid ester containing one (meth)acrylic group and a phosphoric acid ester containing two (meth)acrylic groups, or both of them in an arbitrary ratio. In order to obtain a bismuth compound, which is rarely colored, only a phosphoric acid ester containing one (meth)acrylic group (phosphoric acid monoester) can be coupled.

[0034] When forming a phosphoric acid ester from a phosphoric acid ester containing one (meth)acrylic group and a phosphoric acid ester containing two (meth)acrylic groups, they are preferably used in the following ratio to improve the solubility in the radical- polymerizable monomer and suppression of agglomeration of the bismuth component. More specifically, the phosphoric acid ester is formed from 1 mole of a phosphoric acid ester containing one (meth)acrylic group, and preferably 0.05 to 3 moles, more preferably 0.1 to 2 moles, much more preferably 0 15 to 1 mole of a phosphoric acid ester containing two (meth)acrylic groups. One advantage obtained by containing both a phosphoric acid ester containing one (meth)acrylic group and a phosphoric acid ester containing two (meth)acrylic groups is considered as follows. That is, bismuth is believed to have a preferred site to which a phosphoric acid ester containing one (meth)acrylic group (containing a divalent phosphate group) and a phosphoric acid ester containing two (meth)acrylic groups (containing monovalent phosphate group), and a phosphoric acid ester containing two (meth)acrylic groups, in the preferred binding site is present in an amount in the range from 0.05 to 3 mol, based on 1 mol of a phosphoric acid ester containing one (meth) acrylic group. In the presence of a phosphoric acid ester containing two (meth)acrylic groups, at a given ratio, the concentration of bismuth tends to decrease, but the solubility of bismuth in the radical polymerizable monomer improves. As a result, another advantage is obtained in that the presence of the bismuth component in the hardened product at a high concentration can be ensured in a well balanced manner.

[0035] In a bismuth compound, another compound may be bonded to bismuth by bonding a phosphoric acid ester to bismuth. As can be stated more specifically, salicylic acid or (meth)acrylic acid can also be associated with bismuth. When the phosphoric acid ester of salicylic acid or (meth)acrylic acid is coupled to the same bismuth in order to improve bismuth compound performance and solubility in the radical polymerizable monomer, the ratio between the phosphoric ester and salicylic acid or (meth)acrylic acid is such that the amount of salicylic acid or (meth)acrylic acid is preferably in the range of 0.1 to 10 mol, more preferably 0.1 to 5 mol, much more preferably 0.1 to 1 mol, particularly preferably 0.1 to 0.5 mol, based on 1 mol of phosphoric acid ester. When two or more phosphoric acid esters are present, the above range is based on the total number of moles of these phosphoric acid esters.

[0036] A bismuth compound is a compound in which at least a phosphoric acid ester containing (meth)acrylic group(s) is bound to bismuth. The binding of a phosphoric acid ester containing (meth)acrylic group(s) can be confirmed by the production method or by using elemental analysis of the bismuth compound using IR, NMR (Nuclear Magnetic Resonance Spectrometry) or Energy Dispersive X-Ray Spectrometer (EDX) methods. The number of bonds of each representative selected from salicylic acid or (meth)acrylic acid and a phosphoric acid ester can be ascertained using these methods.

Preferred bismuth compounds of the present invention are represented by the following formulas (3) to (5).

[0037]

[formula 3]

(3)

(3)

[0038]

[formula 4]

(4)

(4)

[0039]

[formula 5]

(5)

(5)

[0040] In the above formulas, each R independently represents a hydrogen atom or a methyl group. In the above formula (3), m+x+y+z=3, and x, y, z and m are the numbers of moles, respectively, of the residue of 2-((meth)acryloyloxy)ethyl hydrogen phosphate (x), the residue of phenyl-2- ((meth)acryloyloxy)ethyl phosphate (y), a bis[2-((meth)acryloyloxy)ethyl]phosphate residue (z) and a (meth)acrylic acid residue (m). In the above formula (4), 2n+u+v+w=3, and u, v, w, and n are the numbers of moles, respectively, of the 2-((meth)acryloyloxy)ethyl hydrogen phosphate residue (u), the phenyl-2- ((meth)acryloyloxy)ethyl phosphate (v), a bis[2-((meth)acryloyloxy)ethyl]phosphate residue (w) and a salicylic acid residue (n). In the above formula (5), 2l+q+r+2s+t=3, and q, r, s, t and l are the numbers of moles, respectively, of the residue of 2-((meth)acryloyloxy)ethyl hydrogen phosphate (q), the residue phenyl 2-((meth)acryloyloxy)ethyl phosphate (r), 2-((meth)acryloyloxy)ethyl phosphate residue (s), bis[2-((meth)acryloyloxy)ethyl]phosphate residue (t), and salicylic acid residue (l).

[0041] In the present invention, the bismuth compounds represented by the above formulas (3) to (5) in each case may be a mixture of a plurality of compounds rather than a single compound. In this case, the number of moles of each residue is the total number of moles of residues of the entire mixture.

In the above formula (3), to obtain a bismuth compound that can be produced at a low temperature and is rarely colored, if m=0, preferably x : y : z=1 : 0.05 ~ 3 : 0.5 ~ 30, more preferably x:y:z=1:0.1~2:1~20, much more preferably x:y:z=1:0.15~1:1.5~10. To suppress staining, m can be 0, and y can be 0.

In the above formula (4), if n=0, x, y, and z in the above specification should read u, v, and w, respectively.

[0042] In the above formula (3), if m is not 0, preferably m : (x+y+z) = 0.1 ~ 10 : 1, more preferably m : (x+y+z) = 0.1 ~ 5 : 1, much more preferably m : (x+y+z) = 0.1 ~ 1 : 1. Even in this case x : y : z=1 : 0.05 ~ 3 : 0.5 ~ 30, more preferably x:y:z=1:0.1~2:1~20, much more preferably x:y:z=1:0.15~1:1.5~10.

[0043] In the above formula (4), if n is not 0, preferably n : (n+v+w) = 1 : 0.1 ~ 1 : 30, more preferably n : (n+v+w) = 1 : 0.2 ~ 1 : 20, much more preferably n : (n+v+w) = 1 : 0.3 ~ 1 : 10, especially n : (n+v+w) = 1 : 0.5 : 5. Even in this case, u : v : w=1 : 20 ~ 0.05 : 40 ~ 0.1 is preferred, more preferably u : v : w=1 : 10 ~ 0.1 : 20 ~ 0.2, much more preferably u : v : w=1 : 5 ~ 0.2 : 10 ~ 0.4.

[0044] Among these compounds, preferably contains at least one compound in which phenyl-2-((meth)acryloyloxy)hydrogen phosphate binds bismuth subsalicylate. In the above formula (5), preferably 1 : (q+r+s+t) = 1 : 0.1 ~ 30, more preferably 1 : (q+r+s+t) = 1 : 0.2 ~ 20, much more preferably 1 : (q+r+s+t) = 1 : 0.3 ~ 10, particularly preferably 1 : (q+r+s+t) = 1 : 0.5 : 5. Even in this case, it is preferable q : r : s : t=1 : 50 ~ 0.1 : 20 ~ 0.05 : 40 ~ 0.1, more preferably q : r : s : t=1 : 30 ~ 0.3 : 10 ~ 0, 1 : 20 ~ 0.2, much more preferably q : r : s : t=1 : 20 ~ 0.5 : 5 ~ 0.2 : 10 ~ 0.4.

These compounds preferably contain at least one compound in which bismuth subsalicylate binds to 2-((meth)acryloyloxy)ethyldihydrophosphate in a ratio of 2:1.

[0045] The bismuth compound of the present invention forms a particulate agglomerate due to its high cohesiveness or low solubility. At this point, when observed using a field emission scanning transmission electron microscope, the long diameter of the agglomerated particle preferably becomes in the range of 0.1 to 30 nm. With the long diameter of the agglomerated particle in the range of 0.1 to 30 nm, it is believed that the bismuth compound is characterized by high solubility in organic matter, especially the radical polymerizable monomer, and high dispersibility in the resulting cured product.

When the long diameter of the agglomerated particle is increased to more than 30 nm, the solubility tends to decrease, and the dispersibility in the resulting cured product tends to fall. When the long diameter of the agglomerated particle is reduced to less than 0.1 nm, production becomes difficult, a product similar to a complex in which three (meth)acrylic acids are bound to bismuth is obtained, the concentration of bismuth becomes low, the solubility in organic matter decreases, and the state dispersion in the resulting cured product tends to deteriorate.

In consideration of productivity, organic solubility, and dispersibility in the obtained cured product for bismuth compound in bismuth compound, the long diameter is preferably in the range of 0.5 to 20 nm, more preferably 0.5 to 10 nm.

[0046] A dispersed agglomerate is formed in the bismuth compound. The bismuth component in a compound in which a phosphoric acid ester and optionally salicylic acid or (meth)acrylic acid is bonded to bismuth, and a compound in which a composite with a phosphoric acid ester and optionally salicylic acid or (meth)acrylic acid is formed by bismuth oxide contained as needed (compound produced from bismuth oxide) can be confirmed using a field emission scanning transmission electron microscope (STEM). The long diameter of the agglomerated particle of the observed bismuth component is preferably in the range of 0.1 to 30 nm.

The following is a description of one preferred method for the production of a bismuth compound.

[0047] <method for producing bismuth compound>

In the present invention, the bismuth compound is preferably produced by reacting the aforementioned bismuth (meth)acrylate or bismuth subsalicylate with a phosphoric acid ester containing (meth)acrylic group(s).

As can be stated more specifically, the bismuth compound of the present invention is preferably produced by reacting the aforementioned bismuth (meth)acrylate or bismuth subsalicylate with a phosphoric acid ester containing methacrylic group(s) in an aliphatic hydrocarbon solvent or an aromatic solvent by addition of as needed polymerization initiator and dehydration.

[0048] <phosphoric acid ester containing (meth)acrylic group(s), (phosphoric acid ester); bismuth compound production method>

As the phosphoric ester containing the (meth)acrylic group(s), a commercially available product may be used. The phosphoric ester may be a phosphoric ester containing one (meth)acrylic group, a phosphoric acid ester containing two (meth)acrylic groups, or a mixture thereof. Examples of a phosphate ester containing one (meth)acrylic group (which may be referred to as "monofunctional phosphoric acid ester" hereinafter) include 2-(methacryloyloxy)ethyl dihydrogen phosphate and phenyl-2-(methacryloyloxy)ethyl hydrogen phosphate. Examples of a phosphoric ester containing two (meth)acrylic groups (which may simply be referred to hereinafter as "difunctional phosphoric acid ester") include bis[2-(methacryloyloxy)ethyl]hydrogen phosphate. As such, a mixture of the aforementioned monofunctional phosphoric acid ester and the difunctional phosphoric acid ester can be used in the reaction.

The amount of phosphoric acid ester can be determined in order to obtain the bismuth compound of interest. More specifically, the amount of phosphoric acid ester is preferably in the range of 0.3 to 10 mol, based on 1 mol of bismuth (meth)acrylate or bismuth subsalicylate.

[0049] In the present invention, as a phosphoric acid ester containing (meth)acrylic group(s), in order to improve compatibility with other monomer, a triester of phosphoric acid such as diphenyl-2-methacryloyloxyethyl phosphate, phenylbis [2-(methacryloyloxyethyl)]phosphate or tris[2-(methacryloyloxyethyl)]phosphate.

When using among them a triester of phosphoric acid containing a phenyl group such as diphenyl-2-methacryloyloxyethyl phosphate or phenylbis[2-(methacryloyloxyethyl)]phosphate, monovalent phenyl phosphoric diester may be introduced into formulas (3) to (5). acid containing one (meth)acrylic group.

[0050] The amount of triester of phosphoric acid is preferably in the range of 0.1 to 20 mol, more preferably 0.2 to 5 mol, based on 1 mol of phosphoric acid ester containing one (meth)acrylic group, and/ or an ester of phosphoric acid containing two (meth)acrylic groups.

[0051] <aliphatic hydrocarbon solvent or aromatic solvent>

In the present invention, it is preferable to mix the aforementioned bismuth (meth)acrylate or bismuth subsalicylate and the aforementioned phosphoric acid ester with each other while stirring in an aliphatic hydrocarbon solvent or an aromatic solvent to carry out their reaction with each other. Since water is currently being produced in the reaction system, the water produced is preferably removed. To easily remove the produced water, an aliphatic hydrocarbon solvent or an aromatic solvent having a high boiling point, specifically 100° C. or more, is preferably used. An aliphatic hydrocarbon solvent or an aromatic solvent may be used as the mixed solution.

[0052] Examples of the aliphatic hydrocarbon solvent and the aromatic solvent include hexane, heptane, nonane, decane, undecane, dodecane, xylene, dimethoxybenzene and their isomers, benzene, toluene, chlorobenzene, bromobenzene, anisole, petroleum ether, petroleum benzene, and benzoin. In the case where the aforementioned bismuth (meth)acrylate or bismuth subsalicylate and the phosphoric acid ester can be completely mixed, the amount of the aliphatic hydrocarbon solvent or the aromatic solvent is not particularly limited. In consideration of the bismuth compound productivity, the aliphatic hydrocarbon solvent or the aromatic solvent is preferably used in an amount in the range of 10 to 100 ml based on 1 g of bismuth (meth)acrylate or bismuth subsalicylate.

[0053] <reaction conditions; bismuth compound production method>

In the present invention, the method for introducing the above-mentioned bismuth (meth)acrylate or bismuth subsalicylate and the above-mentioned phosphoric acid ester into the reaction system is not particularly limited. A method may be used in which the aforementioned bismuth (meth)acrylate or bismuth subsalicylate diluted as necessary with the aforementioned aliphatic hydrocarbon solvent or aromatic solvent and the aforementioned phosphoric acid ester diluted as necessary with the aforementioned aliphatic hydrocarbon solvent or aromatic solvent are jointly added into the interior of the reaction system and mixed with each other with stirring. Another method can be used in which an aliphatic hydrocarbon solvent or an aromatic solvent is introduced into the reaction system beforehand, and the above-mentioned bismuth (meth)acrylate or bismuth subsalicylate diluted as necessary with the above-mentioned aliphatic hydrocarbon solvent or aromatic solvent, and the above-mentioned phosphoric acid ester, diluted with an aliphatic hydrocarbon solvent or an aromatic solvent as needed, are added and mixed together with stirring. One additional method may be used, in which one of the components is introduced into the reaction system in advance, and the other component is introduced into the reaction system for mixing with the first component with stirring. In order to reduce the coloration of the obtained bismuth compound and improve the productivity, the following method is preferably used. First, bismuth (meth)acrylate or bismuth subsalicylate is homogenized in an aliphatic hydrocarbon solvent or an aromatic solvent. In this case, bismuth (meth)acrylate or bismuth subsalicylate may not dissolve. In this case, in order to prevent the presence of bulk material of bismuth (meth)acrylate or bismuth subsalicylate, the bulk material is preferably pulverized using an ultrasonic machine. Thereafter, a method is preferably used in which a phosphoric acid ester is added to an opaque solution containing bismuth (meth)acrylate or bismuth subsalicylate dispersed therein, and stirring and heating are carried out.

[0054] The temperature (reaction temperature) for mixing these components may be a temperature corresponding to reflux at the boiling point of an aliphatic hydrocarbon solvent or an aromatic solvent, but it is preferably in the range of 30 to 110°C, more preferably 40 to 100°C, much more preferably from 45 to 90°C, in order to suppress the coloring of the resulting bismuth compound.

When the reaction temperature is in the range of 30 to 110° C., the interior of the reaction system is preferably depressurized to remove water (dehydration) produced in the interior of the reaction system. This dehydration can be carried out while mixing the aforementioned bismuth (meth)acrylate or bismuth subsalicylate and the aforementioned phosphoric acid ester with each other or after mixing them with each other. In view of the efficiency of the reaction, the dehydration is preferably carried out while mixing them together.

The reaction time is not particularly limited, but is generally in the range of 20 minutes to 2 hours.

The atmosphere for carrying out the reaction may be an atmosphere of air, an atmosphere of an inert gas or an atmosphere of dry air, but preferably an atmosphere of air in view of processability.

[0055] After carrying out the reaction under the aforementioned conditions, the resulting bismuth compound is concentrated by distilling off the solvent, and thereafter, the insoluble opaque component is preferably filtered or separated by centrifugal separation in case there is one. In addition, a solvent that is soluble in the used reaction solvent and does not dissolve the bismuth compound is added to the concentrated reaction solution obtained by this treatment in order to carry out reprecipitation for purification. While maintaining the high-boiling solvent, the above-mentioned decanting operation is repeated to replace the solvent. After the bismuth compound is purified by distilling off the residual solvent and vacuum drying, it can be recovered.

The cured product can be produced by polymerizing and curing the resulting bismuth compound alone. In order to achieve the suitability of the obtained cured product for use, it is preferable to obtain a curable composition containing another radical polymerizable monomer.

[0056] <curable composition>

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

[0057] <radical polymerizable monomer other than bismuth compound>

In the present invention, as the aforementioned radical polymerizable monomer, a common known monomer can be used. Examples thereof include commercially available monofunctional or polyfunctional esters of acrylic acid and methacrylic acid and vinyl compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, vinyl pyridine, vinyl pyrrolidone, acrylonitrile, phenyl methacrylate, benzyl methacrylate, and 2-phenoxyethyl methacrylate. In consideration of the solubility of the aforementioned bismuth compound, a styrenic compound may be used. Examples of the styrenic compound include styrene, methylstyrene and its structural isomers, methylstyrene dimer, chlorostyrene, bromostyrene, and divinylbenzene. The aforementioned radical polymerizable monomers may be used alone or in combination.

[0058] <preferred mixing ratio>

In the curable composition, the mixture ratio of the bismuth compound and the radical polymerizable monomer other than the bismuth compound, as appropriate, is determined according to the intended use of the resulting cured product.

When using a bismuth compound, and taking into account the X-ray shielding effect, dispersibility, and color reduction effect, the radical polymerizable monomer is used in an amount in the range of preferably 1 to 500 parts by mass, more preferably 5 to 300 parts by mass, much more preferably 10 up to 200 mass parts, calculated on 100 mass parts of the bismuth compound.

[0059] <other compounding additives>

The curable composition of the present invention, in addition to the bismuth compound and the radical polymerizable monomer, may contain known compounding additives which are mixed with the radical polymerizable curable composition.

More specifically, a radical polymerization initiator, an antioxidant, a mold release agent to improve mold release, a coloring agent to control the color tone of the cured product, and a chain transfer agent to control polymerizability may be mixed in. These additives during compounding can be mixed in until the effect of the present invention is degraded. Each additive is admixed in the compounding in an amount in the range of preferably 0 to 30 parts by weight, more preferably 0.01 to 20 parts by weight, much more preferably 0.02 to 15 parts by weight, based on 100 parts by weight of the totality of the bismuth compound and a radical polymerizable monomer.

The curable composition can be produced by mixing together the aforementioned bismuth compound and the radical polymerizable monomer, and optionally compounding additives.

[0060] <method for producing a cured product>

In the present invention, a known method can be used to obtain a cured product by curing the above-mentioned curable composition. More specifically, photopolymerization, thermal polymerization, or both can be used. The preferred polymerization method is determined according to the radical polymerization initiator, which is mixed in as needed.

[0061] <physical properties of the resulting cured product>

The curable composition of the present invention can provide a cured product which is highly transparent and rarely colored despite including a large amount of a bismuth component having a high X-ray shielding capability. The cured product obtained from the curable composition of the present invention, when having a thickness of 2 mm, exhibits a transmission at a wavelength in the region of 560 nm of not less than 80%, an X-ray shielding capability equivalent to lead foil with a thickness of 0.02 mm or more, and yellowing not more than 40.

In accordance with the present invention, the content of the bismuth component in the cured product can be set in the range from 5 to 40% (wt.) when calculating 100% (wt.) of the total weight of the cured product.

[0062] <cured product use>

Because the cured product obtained using the present invention demonstrates the ability to protect against radiation despite the transmission of visible light, it can be used as a transparent material that protects from radiation.

EXAMPLES

[0063] The following examples and comparative examples are offered for the purpose of further illustrating the present invention, but are not intended to be limiting in any way.

[0064] <measurement of the long diameter of the bismuth component of the bismuth compound>

A field emission scanning transmission electron microscope (FEM) (Tecnai (registered trademark) F20 from Thermo Fisher Scientific) was used to observe the bismuth compound (observation of the long diameter of the bismuth component). Shape observation and element mapping (mapping of the bismuth component) was carried out in the HAADF-STEM mode at an acceleration voltage of 200 kV. The sample was dropped onto a copper mesh on which a collodion film was stretched, the excess solution was soaked up with a filter paper placed below the mesh, and the sample was dried with air and then in vacuum for observation using a field emission scanning transmission electron microscope.

[0065] <method for analyzing a bismuth compound>

For measurement using the IR method, a Fourier transform infrared spectrophotometer (Spectrum One, manufactured by Perkin Elmer Co., Ltd.) was used. The measurement was carried out using the ATR single reflection method and as a result of integrating data from a quadruple measurement.

For measurement using the TG-DTA method, a differential thermogravimetry simultaneous measurement device (TG8120, manufactured by Rigaku Corporation) was used. The sample was scanned in an air stream in the temperature range from room temperature to 500°C and at a temperature increase rate of 10°C/min.

Microscopic Raman spectroscopy apparatus (NRS-7100, manufactured by JASCO Corporation) was used for measurement using the Raman method, and a 532 nm laser, an objective lens at 100 magnification, a diffraction grating at 600 stroke/mm and apertures with a diameter of 25 µm and a diameter of 4000 µm.

For measurements using ¹ H and ³¹ P-NMR methods, a nuclear magnetic resonance apparatus (JNM-ECA400II, manufactured by JEOL RESONANCE) was used. Hexadeuteroacetone was used as the solvent, and the measurement was carried out at a sample concentration of 1% (wt.).

An X-ray photoelectron spectrometer (ESCA5701ci/MC, manufactured by ULVAC-PHI, Inc.) was used for XPS measurement. Al-Kα monochromatic radiation (14 kV - 330 W) was used as an X-ray source. The aperture diameter was 800 μm, and the photoelectron sampling angle was 45°. The sample was pulverized in an agate mortar, and the resulting powder was fixed on a substrate using carbon adhesive tape and introduced into the measurement chamber for measurement.

[0066] <measuring the physical properties of a cured product containing a bismuth compound>

In the examples, a curable composition containing a bismuth compound, a radical polymerizable monomer, and optionally a thermal polymerization initiator was thermally polymerized to produce a cured product (plate) with a thickness of 2 mm. The resulting cured product was measured for light transmission in the region of 560 nm using an ultraviolet-visible spectrophotometer (UV-2550, manufactured by Shimadzu Corporation).

The yellowing of the cured product (wafer) was measured using the S&M COLOR COMPUTER SM-T, manufactured by Suga Test Instruments Co., Ltd..

In addition, with respect to the ability of the obtained cured product to protect against X-rays, the degree of protection against γ-rays at 59.5 eV emitted from 241 Am was measured as an equivalent thickness of a lead plate.

[0067] Manufacturing Example 1

(production of bismuth methacrylate)

55.9 g (115 mmol) of bismuth nitrate pentahydrate was introduced into a 1000 ml three-necked flask including a stirrer and 500 ml of deionized water was added. To the resulting solution was added 5.4 g (HNO ₃ : 71 mmol) of concentrated nitric acid and lightly stirred. To the resulting solution was added 1.9 g of BHT and 75 ml (885 mmol) of methacrylic acid. A thermometer, a Dimroth condenser and an addition funnel containing a solution obtained by dissolving 37.4 g (935 mmol) of sodium hydroxide in 60 ml of deionized water were attached to this flask, and the flask was placed in an oil bath to heat the contents of the flask from room temperature to 65 °C with stirring for 20 minutes. At this point, almost all of the bismuth nitrate was dissolved, and the BHT compound was retained to a small extent in the solid state. An aqueous solution of sodium hydroxide in a dropping funnel was introduced into this solution at one time. A slightly yellow precipitate was produced and the interior of the reaction system became heterogeneous.

At this point, the temperature of the internal space in the flask became equal to approximately 85°C. The contents were stirred for 1 hour while heating the flask up to 95°C. As it was believed, the reaction was completed when the color of the precipitate turned from yellow to colorless.

[0068] Upon completion of the reaction, the precipitate was filtered off while it was in a hot state when the temperature of the internal space in the flask dropped to 50°C. The precipitate was purified twice using 50 ml of water at 50°C. It was air dried for 2 days. Thus, 55.9 g of bismuth methacrylate was obtained.

A solution containing the resulting sample dissolved in chloroform was observed using the STEM method. As a result, a particle having a diameter of not more than 5 nm and containing Bi as an element could be confirmed. According to the measurement using the IR method, a spectrum of methacrylic acid bound to a metal ion was obtained. As it was determined from the weight loss obtained according to the thermal decomposition measurement, 3 molecules of methacrylic acid were bound to bismuth.

[0069] Example 1

10.6 g (22.8 mmol for bismuth) of bismuth methacrylate prepared in Production Example 1 and 15.3 g of phosphoric acid ester (acidic 2-methacryloyloxyethyl phosphate; MR-200, manufactured by Daihachi Chemical Industry Co., Ltd. (Mixtures of phosphoric acid monoester and phosphoric diester at a ratio of approximately 1:1, 30.3 mmol 2-(methacryloyloxy)ethyl dihydrogen phosphate, 29.1 mmol bis[2- (methacryloyloxy)ethyl]hydrophosphate)) and 300 ml of toluene was added to the flask. They were subjected to ultrasonic dispersion using a bath-type ultrasonic disperser.

The resulting opaque solution was transferred to a 1000 ml four-necked flask equipped with a Dean-Stark trap for reaction by heating at 120° C. in an oil bath with stirring, and the water produced was removed to the outside of the system. As it was believed, the reaction was completed when no more water was produced. A homogeneous dispersion was obtained.

[0070] This solution was transferred to a 500 ml conical beaker and allowed to stand for 2 days. This dispersion was filtered using a 0.2 µm membrane filter containing celite to obtain a colorless and clear solution. This solution was concentrated to 50 ml using an evaporator and 400 ml of hexane was added to this solution. A viscous white precipitate was produced. It was dispersed using a bath-type ultrasonic disperser and allowed to stand. The hexane supernatant was removed by decanting. Purification by removing hexane was repeated three times. The trace amount of hexane remaining at the end was removed using an evaporator and the resulting product was dried in vacuo. 14.3 g of a bismuth compound were obtained, which was a white viscous substance.

The solution resulting from the dissolution of the obtained sample in toluene was observed using the STEM method (Fig. 1). As determined by XPS measurement, there was 1.4 moles of phosphorus per mole of bismuth, and as determined by XPS analysis, there were 1.9 g of phosphorus per mole of bismuth. Despite the difference between these methods due to the low quantitative characterization of phosphorus, according to the analysis using IR, Raman, ¹ H- and ³¹ P-NMR methods, binding to 1 mol of bismuth of 0.2 mol of (meth)acrylic acid and 1.8 mole of phosphoric acid esters. The ratio between the two phosphoric acid esters present was not clearly established due to broadening in the ³¹ P-NMR method.

[0071] Manufacturing Example 2

The reaction was carried out under the same conditions as in Production Example 1 except for using 30 ml of methacrylic acid. The resulting sample was dissolved in chloroform and the resulting solution containing the sample slightly dissolved therein was observed using the STEM method (FIG. 2). In FIG. 2, an agglomerate of lamellar particles having a diameter of not less than 50 nm was observed. Since this compound rarely dissolved in the monomer, the cured product was not evaluated.

[0072] Manufacturing Example 3

A 1000 ml flask equipped with a Dean-Stark trap was charged with 12.1 g of commercially available bismuth oxide fine particles (100 nm Bi ₂ O ₃ particles, manufactured by CIK), 0.50 g of dibutylhydroxytoluene (BHT), and 12.2 g of the product MR-200 (described in example 1) and dispersed in 500 ml of toluene. The resulting dispersion was heated and refluxed at the boiling point with stirring to carry out the dehydration reaction. At the end of the reaction, the insoluble matter was filtered off, and the solvent was distilled off from the filtrate. The resulting dark brown viscous substance was purified three times with hexane and dried. Received 14.7 g of a dark brown viscous substance. As expected, this was a compound in which a phosphoric acid ester was bound to bismuth oxide.

[0073] Example 2

Synthesis was carried out under the same conditions as in Example 1, except for using a 500 ml eggplant flask as the reaction layer and connecting it to an evaporator to carry out the reaction at 50° C. and reduced pressure. Although the reaction was carried out while distilling off the toluene under reduced pressure, when the amount of the remaining gel solution reached approximately 50 ml, 300 ml of toluene was added once more to homogeneously disperse the reaction product. A solution was obtained which was more transparent than the first solution. This solution was once again heated at 50° C. to distill off the solvent under reduced pressure. After concentration, an additional 400 ml of toluene was added to obtain a homogeneous dispersion. To identify the compound, the same measurements were carried out as in Example 1. As measured in Example 2, methacrylic acid was rarely bound, and according to the results of the analysis using the EDRS method, there were 2.5 mol of phosphorus per 1 mol of bismuth, and according to the results of the analysis using the XPS method, it contained 2.6 mol of phosphorus when calculated per 1 mol of bismuth. As confirmed by ³¹ P-NMR analysis, only phosphoric acid monoester was observed as a clear peak. That is, only a bismuth compound was produced in which only the phosphoric acid monoester was bound.

[0074] Example 3

8.2 g of the bismuth compound obtained in Example 1 was dissolved in 6.2 g of a mixed monomer composed of styrene and benzyl methacrylate at a weight ratio of 1:1. In addition, 0.03 g of azobisisobutyronitrile (AIBN) was added to the resulting solution to completely dissolve therein. This monomeric solution was placed under reduced pressure using a vacuum pump to remove dissolved oxygen. This monomer solution was injected into a glass mold having a thickness of 2 mm to polymerize at a maximum temperature of 90° C. for 2 hours to obtain a cured product. For the resulting cured product, yellowing, transmission in the 560 nm region, and X-ray protection ability were measured using the above methods. The results are shown in Table 1.

[0075] Example 4

A cured product was obtained in the same manner as in Example 3, except for using 3.1 g of the bismuth compound obtained in Example 2 and 3.1 g of the mixed monomer used in Example 3. For the obtained cured product, using the above methods measured yellowing, transmission in the region of 560 nm and the ability to protect from x-rays. The results are shown in Table 1.

[0076] Example 5

Into a 500 ml eggplant-shaped flask were added 15.96 g of bismuth(III) subsalicylate (manufactured by Sigma-Aldrich, 44.08 mmol for bismuth), 3.42 g of bismuth(III) nitrate (manufactured by Alfa Aesar, 8 86 mmol for bismuth), 47.23 g of phosphoric acid ester (acidic 2-methacryloyloxyethyl phosphate; MR-200, manufactured by Daihachi Chemical Industry Co., Ltd. (mixture of phosphoric acid monoester and phosphoric diester in the ratio , approximately 1:1, acid number 275 mg KOH/mg, molecular weight based on H ⁺ : 204.02)) and 3.67 g of dibutylhydroxytoluene (BHT, manufactured by Wako Pure Chemical Industries, Ltd.) as an inhibitor polymerization, and then added 300 ml of toluene. The resulting solution was subjected to ultrasonic dispersion using a bath-type ultrasonic disperser.

The resulting opaque solution was transferred to a 500 ml four-necked flask equipped with a Dean-Stark trap for reaction by heating at 120° C. in an oil bath with stirring, and the water produced was removed to the outside of the system. As it was believed, the reaction was completed when no more water was produced. A slightly scattering light yellow solution was obtained in which a light yellow precipitate was produced to a small extent.

[0077] This solution was placed in a centrifugal separator at 20,000×g for 30 minutes to pressure filter the supernatant using a 0.2 µm membrane filter to obtain a slightly scattering light yellow solution. This solution was concentrated down to 50 ml using an evaporator and 400 ml of hexane was added. A viscous white precipitate was produced. It was dispersed using a bath-type ultrasonic disperser and allowed to stand. The hexane supernatant was removed by decanting. Purification by removing hexane was repeated three times. 2.54 g of BHT was added to the resulting white viscous substance, and the resulting mixture was dispersed in 100 ml of acetone. To remove the trace amount of remaining hexane, the organic solvent was distilled off using an evaporator, and acetone was added to achieve a total of 100 ml and dissolve the viscous substance, thereby obtaining a highly diffusing light yellow solution. This solution was placed in a centrifugal separator at 20,000×g for 30 minutes to pressure filter the supernatant using a 0.2 µm membrane filter to obtain a slightly scattering light yellow solution. The organic solvent was removed using an evaporator and the resulting product was dried in vacuo. 55.04 g of a bismuth compound were obtained, which was a scattering light yellow viscous liquid.

[0078] Example 6

To 16.28 g of the bismuth compound obtained in Example 5 was added 0.12 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65) to completely dissolve it. This monomeric solution was placed under reduced pressure using a vacuum pump to remove dissolved oxygen. This monomer solution was injected into a glass mold having a thickness of 2 mm to polymerize at a maximum temperature of 90° C. for 3 hours to obtain a cured product. For the resulting cured product, yellowing, transmission in the 560 nm region, and X-ray protection ability were measured using the above methods. The results are shown in Table 1.

As determined by analysis of the obtained cured product, as measured by XPES, 2.29 moles of phosphorus were contained per 1 mole of bismuth.

[0079] Example 7

To a 1000 ml eggplant-shaped flask were added 37.59 g of bismuth (III) subsalicylate (manufactured by Sigma-Aldrich, 103.81 mmol with respect to bismuth), 16.72 g of phosphoric acid diester (bis[(2-methacryloyloxy) ethyl]phosphate (manufactured by Sigma-Aldrich, 51.89 mmol)), 18.81 g triester of phosphoric acid (diphenyl-2-methacryloyloxyethyl phosphate) (MR-200, manufactured by Daihachi Chemical Industry Co., Ltd., 51, 92 mmol) and 18.59 g of dibutylhydroxytoluene (BHT, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization inhibitor, and 700 ml of toluene was added. They were subjected to ultrasonic dispersion using a bath-type ultrasonic disperser to obtain an opaque solution.

The resulting opaque solution was transferred to a 1000 ml four-necked flask equipped with a Dean-Stark trap for reaction by heating at 120° C. in an oil bath with stirring, and the water produced was removed to the outside of the system. As it was believed, the reaction was completed when no more water was produced. A slightly scattering light yellowish green solution was obtained in which a light yellow precipitate was produced to a small extent.

[0080] This solution was placed in a centrifugal separator at 20,000 x g for 30 minutes to decant the supernatant, activated carbon was added here, and the resulting product was placed in a centrifugal separator at 20,000 x g for 30 minutes. The supernatant was pressure filtered using a 0.2 µm membrane filter to obtain a light yellow clear solution. This solution was concentrated down to 50 ml using an evaporator and 400 ml of hexane was added. A viscous white precipitate was produced. It was dispersed using a bath-type ultrasonic disperser and allowed to stand. The hexane supernatant was removed by decanting. Purification by removing hexane was repeated three times. To the resulting light yellow gummy solid was added 0.50 g of BHT to be dispersed in 100 ml of acetone. To remove the trace amount of remaining hexane, the organic solvent was distilled off using an evaporator and acetone was added once more to ensure that a total of 100 ml was reached and the solid was dissolved. A scattering light yellowish green solution was obtained. This solution was placed in a centrifugal separator at 20,000×g for 90 minutes and the supernatant was filtered under pressure using a 0.2 μm membrane filter to obtain a slightly scattering light yellow solution. The organic solvent was removed using an evaporator and the resulting product was dried in vacuo. 38.60 g of bismuth compound were obtained, which was a light yellow transparent syrupy fluid.

[0081] Example 8

To 15.04 g of the bismuth compound obtained in Example 7, 2.47 g of styrene was added to dissolve it homogeneously. In addition, 0.12 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65) was added to the resulting solution to completely dissolve the bismuth compound. This monomeric solution was placed under reduced pressure using a vacuum pump to remove dissolved oxygen. This monomer solution was injected into a glass mold having a thickness of 2 mm to polymerize at a maximum temperature of 90° C. for 3 hours to obtain a cured product. For the resulting cured product, yellowing, transmission in the 560 nm region, and X-ray protection ability were measured using the above methods. The results are shown in Table 1.

As determined from analysis of the resulting cured product, XPES analysis contained 0.54 moles of phosphorus per 1 mole of bismuth.

[0082] Comparative Example 1

A cured product was obtained in the same manner as in Example 3, except for using 7.1 g of the bismuth oxide solute obtained in Production Example 3 and 1.0 g of the mixed monomer used in Example 3. For the resulting cured product, Using the above methods, yellowing, transmission in the region of 560 nm and the ability to protect from X-rays were measured. The results are shown in Table 1.

[0083] [Table 1]

Table 1

Yellowing transmission
in area
560 nm (%) X-ray shielding capacity (mm Pb/2 mm) Etc. 3 35.1 52.6 0.067 Etc. 4 15.9 83.8 0.042 Etc. 6 10.5 86.6 0.054 Etc. 8 21.4 85.1 0.100 Wed pr. 1 209.6 0.2 0.073

Ex: example

Wed eg: comparative example

[0084] For each of the plates obtained in Examples 3, 4, 6, and 8 and Comparative Example 1, Table 1 shows yellowing, transmission in the 560 nm region, and X-ray shielding ability. Although the plate of Comparative Example 1 showed high X-ray shielding ability due to the amount of bismuth oxide, it was highly colored and rarely transmitted light. Meanwhile, the plates of Examples 3, 4, 6, and 8 exhibited the ability to protect, corresponding to the amount of bismuth, such high transparency that they can be used as optical materials, and acceptable yellowing.

Claims (10)

1. Bismuth compound to obtain a cured product in which a phosphoric acid ester containing a (meth)acrylic group is bonded to bismuth, where a phosphoric acid ester is at least one compound selected from the group consisting of 2-((meth)acryloyloxy)ethyl dihydrogen phosphate, bis[2-((meth)acryloyloxy)ethyl]hydrogen phosphate, and phenyl-2-( (meth)acryloyloxy)ethyl phosphate, and wherein the bismuth compound is obtained by reaction between bismuth (meth)acrylate or bismuth subsalicylate and a phosphoric acid ester containing (meth)acrylic group(s) to effect dehydration. 2. A bismuth compound according to claim 1, wherein salicylic acid or (meth)acrylic acid is also bonded to bismuth. 3. The bismuth compound according to claim 1, wherein the phosphoric acid ester comprising (meth)acrylic acid is used to obtain the bismuth compound in an amount in the range of 0.3 to 10 mol, based on 1 mol of bismuth (meth)acrylate or subsalicylate bismuth. 4. Bismuth compound according to any one of paragraphs. 1-3, wherein bismuth (meth)acrylate or bismuth subsalicylate is reacted with a phosphoric acid ester containing a (meth)acrylic group to effect dehydration in an aliphatic hydrocarbon solvent or an aromatic solvent. 5. Bismuth compound according to any one of paragraphs. 1-4, wherein bismuth (meth)acrylate or bismuth subsalicylate is reacted with a phosphoric acid ester containing a (meth)acrylic group to effect dehydration under reduced pressure at a temperature in the range of 50 to 100°C. 6. Curable composition containing a bismuth compound according to any one of paragraphs. 1-5 and a radical polymerizable monomer other than a bismuth compound. 7. The curable composition of claim 6, wherein the radical polymerizable monomer comprises a styrenic compound. 8. A cured product from a curable composition according to claim 6 or 7.

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