JP7622939B2 - Cationically polymerizable curable composition - Google Patents

Description

The present invention relates to a cationically polymerizable hardenable composition, particularly a cationically polymerizable hardenable composition that can be suitably used as a dental hardenable composition.

In dental treatment, dental composite restorative materials, which are used to fill and harden tooth sockets after caries removal to restore them, are composed mainly of polymerizable monomers, fillers, and polymerization initiators. Radical polymerizable monomers are generally used as polymerizable monomers, but because they shrink when hardened, they can sometimes impair the adhesion between the tooth and the hardened body, causing the hardened body to fall off or cause secondary caries. In light of this, dental composite restorative materials that reduce shrinkage during polymerization (polymerization shrinkage) have been studied, and a dental composite restorative material with improved polymerization shrinkage has been proposed that uses cationic polymerizable monomers such as epoxy compounds and oxetane compounds and a photoacid generator-based photopolymerization initiator (see, for example, Patent Document 1).

In such cationic polymerization type dental composite restorative materials, because they can be rapidly cured in the oral cavity, it is considered preferable to use, as the photoacid generator-based photopolymerization initiator, an iodonium salt-based photopolymerization initiator or a sulfonium salt-based photopolymerization initiator that has high polymerization initiation activity, particularly one that has an anion such as trifluoromethanesulfonate or tetrakispentafluorophenylborate that has low nucleophilicity toward anions (see Patent Document 1).

However, the cationic polymerization type dental composite restorative material containing the highly active photoacid generator-based photopolymerization initiator as described above has the problem that it gels relatively early during storage. Therefore, various additives for suppressing the gelation of photocationically curable compositions have been investigated, and a method of adding a phenolic antioxidant in combination with hindered amines that function as hydrogen ion scavengers or salts of organic acids that do not have photoacid generating ability has been proposed (see Patent Documents 2 and 3).

On the other hand, it is known that when a radiopaque filler is added to a cationic polymerization type dental composite restorative material in order to impart radiographic contrast to the cured material, the curing property may be inhibited or the storage stability may decrease, and that such problems can be avoided by using a special radiopaque filler prepared by melt processing at high temperatures of 1500 to 3000°C using a plasma melting method or the like (see Patent Document 4).

JP 2007-15946 A JP 2006-249040 A JP 2007-131841 A Special Publication No. 2004-517132

As mentioned above, the gelation problem in cationic polymerizable curable compositions containing a highly active photoacid generator-based photopolymerization initiator can be prevented by adding a phenolic antioxidant and a hydrogen ion scavenger in combination. However, in Patent Documents 2 and 3, the curability after long-term storage is not examined, and the effect of long-term storage on the curability is unclear. In addition, since the hydrogen ion scavenger inhibits the progress of cationic polymerization, there is a concern that it will reduce the curing speed when irradiated with light. In particular, in dental applications, since it may be used in the patient's oral cavity, it is required to cure quickly at room temperature. Therefore, if the curability is reduced by adding a hydrogen ion scavenger, there is a risk that the applications and methods of use will be restricted.

Furthermore, it is unclear whether the additives mentioned above have an effect of suppressing the occurrence of the above-mentioned phenomena (such as polymerization inhibition and reduced storage stability) that occur when radiopaque fillers are blended. If they cannot be effectively suppressed, a special radiopaque filler such as that described in Patent Document 4 must be used, which would be a major constraint.

On the other hand, the cationic polymerizable curable composition containing the X-ray opaque filler described in Patent Document 4 is said to have good storage stability and high reactivity, but its curability after long-term storage is unknown.

The present invention aims to provide a cationically polymerizable curable composition that contains a highly active photoacid generator-based photopolymerization initiator and a filler, and that can be stably stored for long periods of time without gelling without using an additive consisting of a combination of a phenolic antioxidant and a hydrogen ion trapping agent, and that has good curability not only immediately after preparation (initial curability) but also after long-term storage, and that can be provided with X-ray contrast properties while maintaining these characteristics.

The present invention is to solve the above-mentioned problems. A first aspect of the present invention is a cationically polymerizable curable composition comprising a cationically polymerizable monomer, a filler, and an iodonium salt-based photoacid generator and/or a sulfonium salt-based photoacid generator,
The filler includes an acid-base filler made of a powder of a composite oxide of a B-element, which is defined as an element capable of forming a basic oxide having an electronegativity of less than 2.0, an N-element, which is defined as an element capable of forming a neutral oxide having an electronegativity of 2.0 to 2.8, and an B-element, which is defined as an element capable of forming an acidic oxide having an electronegativity of more than 2.8;
when the abundance ratios of the B-element, the N-element and the A-element in the composite oxide are expressed as the ratio of the mass of the basic oxide:B and the mass of the acidic oxide:A based on the mass of the intermediate oxide:N, the abundance ratios are B/N=0.03 to 3.0 and A/N=1.9 to 3.0,
The composite oxide powder constituting the acid-base filler is
a basic region that has basic sites on its surface and undergoes a color change when contacted with a Hammett indicator having a color change pKa in the range of 7.2 to less than 9.3;
an acidic region , which has acidic sites on its surface and undergoes a color change when contacted with a Hammett indicator having a color change pKa in the range of greater than pKa 3.3 to 4.8;
having
The content of the acidic/basic filler is 10 to 400 parts by mass based on 100 parts by mass of the cationic polymerizable monomer.
The present invention relates to a cationically polymerizable curable composition.

In the above-mentioned cationic polymerizable curable composition (hereinafter also referred to as "cationically polymerizable curable composition of the present invention"), it is preferable that the element capable of forming an oxide having an electronegativity of less than 2.0 is at least one selected from the group consisting of Cs, K, and Na, the element capable of forming an oxide having an electronegativity of 2.0 to 2.8 is at least one selected from the group consisting of Ba, Sr, Ca, Mg, Zn, Li, Al, and Zr, and the element capable of forming an oxide having an electronegativity of more than 2.8 is at least one selected from the group consisting of La, B, Ta, Si, Rh, and P.

The filler preferably contains a non-basic filler made of a powder of a substance that does not have a region that exhibits basicity of pKa 7.2 or more, and the content of the non-basic filler is preferably 1 to 380 parts by mass per 100 parts by mass of the cationic polymerizable monomer.

It is also preferable that the average primary particle size of the acid/base filler is 10 to 1000 nm, and the refractive index of the composite oxide constituting the acid/base filler at 25°C is 1.45 to 1.60 with respect to the sodium d line.

Furthermore, the cationically polymerizable monomer is preferably an epoxy compound.

The second aspect of the present invention is a dental hardenable composition comprising the cationically polymerizable hardenable composition of the present invention (hereinafter also referred to as the "dental hardenable composition of the present invention").

According to the present invention, in a cationic polymerizable curable composition containing an acid generator initiator, gelation can be prevented and storage stability can be improved without using an additive consisting of a combination of a phenolic antioxidant and a hydrogen ion scavenger. Moreover, it is possible to maintain the initial curability even after long-term storage. Furthermore, since the acid/base filler also includes one having radiopaqueness, the use of such an acid/base filler can impart radiopaque properties to the cured product without separately blending another radiopaque filler (i.e., a radiopaque filler that may have a detrimental effect or a radiopaque filler as described in Patent Document 4).

The cationic polymerizable curable composition of the present invention has the above-mentioned effects, and therefore can be suitably used not only for dental applications but also for various applications requiring such properties. For example, it can be suitably used as a dental filling and restorative material, adhesive, paint, optical material, etc.

The reason why such an effect is obtained is that an acid-base filler made of a powder of a composite oxide of an element capable of forming an oxide with an electronegativity of less than 2.0, an element capable of forming an oxide with an electronegativity of 2.0 to 2.8, and an element capable of forming an oxide with an electronegativity of more than 2.8 is blended, the composite oxide having a basicity region of pKa 7.2 or more and less than 9.3, and an acidity region of pKa 3.3 or more and 4.8 or less. The detailed mechanism by which the effect is exhibited is not necessarily clear, and the present invention is not bound by any logic, but the inventors presume that it is as follows.

That is, it is believed that gelation during storage is caused by a small amount of acid generated by slight decomposition of the acid generator during storage, and the small amount of acid is captured by the basic points present in the basic region of the acid-basic filler, so that the gelation can be prevented. At this time, since an acidic region exists around the basic region, the acid capturing power of the basic points is weakened by the influence of the acidic region (acid points present in the acidic region), and the capturing speed is slow, but since there is a moderate distance between the basic region and the acidic region and the time of coexistence with the acid is long, it is believed that even a small amount of acid can be captured. On the other hand, when a large amount of acid is generated at once by making the acid generator function (as a polymerization initiator) by light irradiation or the like, the acid cannot be captured, and substantially all of the acid can contribute to the polymerization reaction, so it is presumed that the initial and long-term curability after storage are well maintained.

As described above, the cationic polymerizable curable composition of the present invention is most characterized by the incorporation of a specific amount of acidic and basic fillers, and apart from this, there is no significant difference between the composition and conventional cationic polymerizable curable compositions. For example, the cationic polymerizable monomer and acid generator incorporated in the cationic polymerizable curable composition of the present invention, as well as other fillers (other than acidic and basic fillers) incorporated as necessary, may be any of those that are disclosed in Patent Document 1 and are usable in dental cationic curable compositions, etc., without any particular restrictions.

The cationic polymerizable curable composition of the present invention will be described in detail below, including these. In this specification, unless otherwise specified, the notation "x to y" using numerical values x and y means "x or more and y or less." In such notations, when a unit is added only to the numerical value y, the unit is also applied to the numerical value x.

1. Cationic Polymerizable Monomer The cationic polymerizable monomer is not particularly limited as long as it is a compound that is polymerized by an acid generated by decomposition of an acid generator, and examples of the cationic polymerizable monomer that can be used include vinyl ether compounds, epoxy compounds, oxetane compounds, cyclic ether compounds, bicyclic orthoester compounds, cyclic acetal compounds, bicyclic acetal compounds, and cyclic carbonate compounds.

Specific examples of epoxy compounds that can be suitably used include 1,2-epoxypropane, epichlorohydrin, methyl glycidyl ether, cyclohexene oxide, phenyl glycidyl ether, 1,3-butadiene dioxide, ethylene glycol diglycidyl ether, 1,4-bis(3,4-epoxycyclohexylmethyloxymethyl)benzene, methylbis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenylsilane, glycerol triglycidyl ether, pentaerythritol triglycidyl ether, 3,3',3'',3'''-[(2,4,6,8-tetramethylcyclotetrasiloxane-2,4,6,8-tetrayl)tetra-2,1-ethanediyl]tetrakis[7-oxabicyclo[4.1.0]heptane], and the like.

Specific examples of suitable oxacene compounds include trimethylene oxide, 3-methyl-3-oxetanylmethanol, 3,3-diethyloxetane, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 1,4-bis(3-ethyl-3-oxetanylmethyloxy)benzene, 4,4'-bis(3-ethyl-3-oxetanylmethyloxy)biphenyl, ethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, diethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, bis(3-ethyl-3-oxetanylmethyl)diphenoate, and pentaerythritol tetrakis(3-ethyl-3-oxetanylmethyl)ether.

Specific examples of other cationic polymerizable monomers that can be suitably used include cyclic ether compounds such as tetrahydrofuran and oxepane; bicyclic orthoester compounds such as bicycloorthoesters, spiroorthoesters, and spiroorthocarbonates; cyclic acetal compounds such as 1,3,5-trioxane, 1,3-dioxolane, oxepane, 1,3-dioxepane, 4-methyl-1,3-dioxepane, and 1,3,6-trioxacyclooctane; bicyclic acetal compounds such as 2,6-dioxabicyclo[2.2.1]heptane, 2,7-dioxabicyclo[2.2.1]heptane, and 6,8-dioxabicyclo[3.2.1]octane; and cyclic carbonate compounds such as ethylene carbonate and trimethylene carbonate.

Among these, epoxy compounds and oxetane compounds are preferably used because of their good polymerizability. The above cationic polymerizable monomers may be used alone or in combination of two or more kinds.

2. Acid Generator As the acid generator, a chemical acid generator, a photoacid generator, a thermal acid generator, etc., which are used as an acid generator capable of polymerizing the above-mentioned cationic polymerizable monomer, can be used without any particular limitation. The amount of the photoacid generator is not particularly limited as long as it is an amount capable of initiating polymerization by light irradiation, but is usually in the range of 0.001 to 10 parts by mass per 100 parts by mass of the cationic polymerizable monomer. From the viewpoint of the polymerization rate and various physical properties (e.g., weather resistance and hardness) of the obtained cured body, it is preferable to mix 0.05 to 5 parts by mass based on the above standard.

In dental applications where the composition is cured in the oral cavity, it is preferable to use a photoacid generator as the acid generator. The photoacid generator means a polymerization initiator made of a compound that is excited by light irradiation, decomposes the photoacid generator, and generates an acid, which becomes a polymerization initiator species and can initiate cationic polymerization. Examples of such photoacid generators include iodonium salt-based photoacid generators, sulfonium salt-based photoacid generators, pyridinium salt-based photoacid generators, and trihalomethyl-S-triazine-based photoacid generators. Any of these can be used, but it is preferable to use an iodonium salt-based photoacid generator and/or a sulfonium salt-based photoacid generator because of their high polymerization activity, and it is particularly preferable to use an iodonium salt-based photoacid generator. In addition, for photoacid generators that do not absorb light in the near ultraviolet to visible range, it is preferable to mix about 0.001 to 20 moles, preferably 0.005 to 10 moles, of a sensitizer compound per mole of photoacid generator in order to make the photoacid generator exhibit polymerization activity by irradiation with such light.

Examples of iodonium salt-based photoacid generators that can be suitably used include diaryliodonium salt-based compounds consisting of cations such as diphenyliodonium, bis(p-chlorophenyl)iodonium, ditolyliodonium, bis(p-tert-butylphenyl)iodonium, p-isopropylphenyl-p-methylphenyliodonium, bis(m-nitrophenyl)iodonium, p-tert-butylphenylphenyliodonium, p-methoxyphenylphenyliodonium, bis(p-methoxyphenyl)iodonium, p-octyloxyphenylphenyliodonium, p-phenoxyphenylphenyliodonium, and bis(p-dodecylphenyl)iodonium, and anions such as chloride, bromide, p-toluenesulfonate, trifluoromethanesulfonate, tetrafluoroborate, tetrakispentafluorophenylborate, tetrakispentafluorophenylgallate, hexafluorophosphate, hexafluoroarsenate, and hexafluoroantimonate. Among these, from the viewpoints of solubility in cationic polymerizable monomers and polymerization activity, it is preferable to use a compound having hexafluoroantimonate, tetrakispentafluorophenylborate, or tetrakispentafluorophenylgallate as the anion, and from the viewpoint of low toxicity, it is particularly preferable to use a compound having tetrakispentafluorophenylborate as the anion.

Sulfonium salt compounds that are suitable components of sulfonium salt-based photoacid generators include chlorides, bromides, p-toluenesulfonate, trifluoromethanesulfonate, tetrafluoroborate, tetrakispentafluorophenylborate, tetrakispentafluorophenylgallate, hexafluorophosphate, hexafluoroarsenate, and hexafluoroantimonate salts of triphenylsulfonium, p-tolyldiphenylsulfonium, p-tert-butylphenyldiphenylsulfonium, and diphenyl-4-phenylthiophenylsulfonium.

In addition, examples of sensitizers used in combination with photoacid generators include acridine dyes, benzoflavin dyes, condensed polycyclic aromatic compounds such as anthracene and perylene, phenothiazine, diaryl ketone compounds, α-diketone compounds, and coumarin compounds that absorb light in the near ultraviolet to visible range.

3. Filler The filler to be blended in the cationic polymerizable curable composition of the present invention must contain at least 20 to 400 parts by weight, preferably 40 to 150 parts by weight, of an acidic/basic filler relative to 100 parts by weight of the cationic polymerizable monomer. If this condition is not satisfied, the above-mentioned effect cannot be obtained. In order to ensure the proper properties (operability) of a dental curable composition, the filler may contain 1 to 380 parts by weight, particularly 60 to 190 parts by weight, of a non-basic filler made of a powder of a substance that does not have a basic region of pKa 7.2 or more relative to 100 parts by weight of the cationic polymerizable monomer. The stabilizing effect tends to decrease when a non-basic filler is blended, but if the blending amount is at this level, a stabilizing effect that can withstand practical use can be obtained. Below, fillers such as acidic/basic fillers and non-basic fillers will be described in detail.

3-1. Acid/Basic Filler In the present invention, the acid/basic filler refers to a filler made of a powder of a complex oxide of an element capable of forming an oxide having an electronegativity of less than 2.0 (hereinafter also referred to as an "acidic oxide"), an element capable of forming an oxide having an electronegativity of 2.0 to 2.8 (hereinafter also referred to as an "intermediate oxide"), and an element capable of forming an oxide having an electronegativity of more than 2.8 (hereinafter also referred to as an "acidic oxide"), the complex oxide having a basic region of pKa 7.2 or more and less than 9.3 (hereinafter also referred to as a "basic region") and an acidic region of pKa more than 3.3 and not more than 4.8 (hereinafter also referred to as an "acidic region").

Here, the electronegativity of an oxide means a weighted average of the Pauling electronegativities of the elements constituting the oxide, depending on the ratio of each element contained. For example, the electronegativity of boron oxide (B ₂ O ₃ ) is calculated based on the electronegativity of boron: 2.04, the electronegativity of oxygen: 3.44, the number of boron atoms: 2, the number of oxygen atoms: 3, and the total number of atoms: 5, as follows:
Formula: {(2.04×2)+(3.44×3)}/5=2.88
Therefore, the electronegativity is 2.88. The electronegativity values determined in this manner for representative oxides are shown in Table 1.

In addition, the basic region, which is a region showing basicity with a pKa of 7.2 or more and less than 9.3, means a region that has a basic site on the surface and changes color when contacted with a Hammett indicator having a color change pKa within the above pKa range. And, its existence can be confirmed by a color change when contacted with a Hammett indicator. That is, Table 2 shows representative Hammett indicators and their color change pKas, and it can be confirmed by the fact that it changes color when contacted with bromothymol blue, which has a color change pKa of 7.2, and various Hammett indicators, which have a color change pKa of 7.2 or more and less than 9.3, and does not change color when contacted with phenolphthalein, which has a color change pKa of 9.3. Similarly, the acidic region, which is a region showing acidity with a pKa of more than 3.3 and less than 4.8, means a region that has an acidic site on the surface and changes color when contacted with a Hammett indicator having a color change pKa within the above pKa range. Its presence can be confirmed by the fact that it changes color when it is brought into contact with a Hammett indicator such as methyl red or 4-phenylazo-1-naphthylamine, which has a discoloration pKa of more than 3.3 and not more than 4.8, but does not change color when it is brought into contact with a Hammett indicator having a discoloration pKa outside the above range, such as methyl yellow (discoloration pKa: 3.3) or 2-aminoazotoluene (discoloration pKa: 2.0), which has a discoloration pKa of not more than 3.3. In the present invention, a plurality of samples are prepared in which 1 g of composite oxide powder is suspended in 3 ml of toluene dehydrated by a molecular sieve, and for each sample, 0.3 ml of a 1 mass % toluene solution of a Hammett indicator having each discoloration pKa is dropped, the suspension is shaken, and the presence or absence of a color change in the suspension is visually confirmed to confirm the presence or absence of an acidic/basic region.

In the composite oxide constituting the acid-base filler, an element capable of forming an oxide with an electronegativity of less than 2.0 (basic oxide) is defined as a B-element, an element capable of forming an oxide with an electronegativity of 2.0 to 2.8 (intermediate oxide) is defined as an N-element, and an element capable of forming an oxide with an electronegativity of more than 2.8 (acidic oxide) is defined as an A-element. The B-element is preferably at least one element selected from the group consisting of Cs, K, and Na. The N-element is preferably at least one element selected from the group consisting of Ba, Sr, Ca, Mg, Zn, Li, Al, and Zr. The A-element is preferably at least one element selected from the group consisting of La, B, Ta, Si, Rh, and P.

Furthermore, from the viewpoint of effectiveness, the abundance ratios of the B-element, N-element, and A-element in the composite oxide constituting the acid-base filler are preferably B/N=0.03-3.0 and A/N=1.9-3.0, and more preferably B/N=2.0-3.0 and A/N=2.0-3.0, expressed as the ratio of the mass of the basic oxide:B and the mass of the acidic oxide:A based on the mass of the intermediate oxide:N.

For acidic and basic fillers, surface treatment can be performed to improve their affinity with various monomers, but it should be noted that the surface treatment may change the surface properties of the filler, i.e., its basicity or acidity. In view of reactivity with the surface treatment agent when performing surface treatment, it is preferable that the A-element contains Si.

The powder of the complex oxide constituting the acidic/basic filler can be obtained by using a mixed powder obtained by mixing the powder of the basic oxide, the powder of the intermediate oxide, and the powder of the acidic oxide so as to satisfy the above B/N and A/N as a raw material, melting or sintering at a high temperature, and then appropriately pulverizing the mixed powder . In addition, powders made of a complex oxide of available B-elements, N-elements, and A-elements, whose content ratios satisfy the above conditions, and which have not been subjected to any special surface treatment, are generally considered to be usable as acidic/basic fillers. In the case where a surface treatment has been performed, it can be confirmed whether or not the powder corresponds to an acidic/basic filler by the confirmation method using the Hammett indicator described above.

When used in a dental hardenable composition, the refractive index of the composite oxide with respect to the sodium d line at 25° C. is preferably 1.45 to 1.60, because light scattering between the polymerizable monomer and the polymer is unlikely to occur and the composite oxide is excellent in aesthetics when filled into a tooth. The average primary particle size of the powder constituting the acid-base filler is preferably 10 to 1000 nm, and more preferably 100 to 600 nm, because gloss is easily obtained when polishing is performed after filling into a tooth, and the workability and aesthetics are excellent.

Furthermore, in order to be able to impart X-ray contrast without blending other X-ray opaque fillers, it is preferable that the acid/base filler has X-ray opacity. In order to impart X-ray opacity, it is sufficient to include an element having an atomic number of at least 30 as a B-element, N-element, or A-element.

3-2. Non-basic filler In the present invention, the non-basic filler means a filler made of a powder of a substance that does not have a region showing basicity of pKa 7.2 or more. As the non-basic filler, an oxide of the N-element or a composite oxide of a plurality of different N-elements can be used. These neutral fillers may be blended as they are, or may be blended as a so-called "organic-inorganic composite filler" in which the filler is combined with a resin by a method such as mixing with a radical polymerizable monomer, curing the mixture, and pulverizing the mixture. In addition, when blending as it is, it is preferable to perform a surface treatment using a silane coupling agent or the like.

In addition, the basic oxide or the composite oxide constituting the acid-base filler may be surface-treated to have no regions that exhibit a basicity of pKa 7.2 or more.

In the non-basic filler, the oxide or composite oxide constituting the filler preferably has a refractive index of 1.45 to 1.60 at 25° C. with respect to the sodium d line, and the powder preferably has an average primary particle size of 10 to 1000 nm, particularly preferably 100 to 600 nm.

Furthermore, the non-basic filler may be an organic filler. Suitable organic fillers include powders made of organic polymers such as polymethyl methacrylate, polyethyl methacrylate, methyl methacrylate-ethyl methacrylate copolymer, crosslinked polymethyl methacrylate, crosslinked polyethyl methacrylate, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, acrylonitrile-styrene copolymer, and acrylonitrile-butadiene-styrene copolymer.

4. Other Components 4-1. Radical Polymerizable Monomer The cationic polymerizable curable composition of the present invention can also contain an addition polymerization type radical polymerizable monomer such as a (meth)acrylate monomer, if necessary. By containing a radical polymerizable monomer, the apparent curing time can be shortened. However, since the addition polymerization type radical polymerizable monomer may cause phase separation from the cationic polymerizable monomer after curing, it is not preferable to contain a large amount of it.

When a radical polymerizable monomer is blended, the blending amount is preferably 43 parts by mass or less, and more preferably 12 parts by mass or less, per 100 parts by mass of the cationic polymerizable monomer.

Specific examples of such radical polymerizable monomers include methyl (meth)acrylate, glycidyl (meth)acrylate, 2-cyanomethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, allyl (meth)acrylate, 2-hydroxyethyl mono(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol Examples of (meth)acrylate monomers include ricol di(meth)acrylate, 2,2-bis[4-(meth)acryloyloxyethoxyphenyl]propane, 2,2-bis[4-(meth)acryloyloxyethoxyethoxyphenyl]propane, 2,2-bis{4-[3-(meth)acryloyloxy-2-hydroxypropoxy]phenyl}propane, 1,4-butanediol di(meth)acrylate, 1,3-hexanediol di(meth)acrylate, urethane di(meth)acrylate, and trimethylolpropane di(meth)acrylate.

When these radical polymerizable monomers are blended, it is preferable to blend a radical polymerizable initiator together. The radical polymerizable initiator is not particularly limited as long as it does not adversely affect the storage stability of the cationic polymerizable curable composition of the present invention, but when a photoacid generator is used, it is preferable to use a photopolymerization initiator.

4-2. Various Additives, etc. Various additives, such as a polymerization inhibitor, an ultraviolet absorber, a dye, an antistatic agent, a pigment, a fragrance, an organic solvent, and a thickener, may be blended into the cationically polymerizable curable composition of the present invention, as necessary, within the range not impairing the effects of the present invention.

5. Method for producing and using the cationic polymerizable curable composition of the present invention The cationic polymerizable curable composition of the present invention can be produced by mixing each component. Specifically, the components are weighed out in a predetermined amount and mixed to form a paste. At this time, the mixing conditions are adopted under conditions under which no acid is generated according to the type of acid generator used. For example, when a photoacid generator is used, it is necessary to mix in a dark place, and when a thermal acid generator is used, it is necessary to mix at room temperature or at a low temperature. Then, the produced cationic polymerizable monomer of the present invention is stored in the dark or at room temperature or at a low temperature until it is used. When a chemical acid generator is used, the constituent components are divided and mixed with other components so that the chemical acid generator does not function, and a plurality of agents containing each component are prepared, stored in a divided state, and each agent is mixed when used.

As a means for curing the cationic polymerizable curable composition of the present invention, any known polymerization means may be used appropriately according to the polymerization initiation mechanism of the polymerization initiator used. Specifically, light irradiation from a light source such as a carbon arc, a xenon lamp, a metal halide lamp, a tungsten lamp, a fluorescent lamp, sunlight, a helium cadmium laser, an argon laser, or heating using a heating polymerization device, or a combination of these, may be used without any restrictions. When polymerizing by light irradiation, the irradiation time varies depending on the wavelength and intensity of the light source, and the shape and material of the cured body, so it may be determined in advance by preliminary experiments, but it is generally preferable to adjust the mixing ratio of the various components so that the irradiation time is in the range of about 5 to 60 seconds.

The present invention will be specifically illustrated below with examples, but the present invention is not limited to these examples in any way.

First, we will explain the substances and their abbreviations used as raw materials for the cationic polymerizable curable compositions prepared in the Examples and Comparative Examples, and the evaluation methods for the prepared cationic polymerizable curable compositions.

1. Substances and their abbreviations 1-1. Cationic polymerizable monomer EP-1: Compound represented by the following formula (KR470, manufactured by Shin-Etsu Chemical Co., Ltd.)

OX-1: Compound represented by the following formula (manufactured by Toagosei Co., Ltd., OXT-121)

1-2. Polymerization initiator (1) Photoacid generator DPIB: 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate (Tokyo Chemical Industry Co., Ltd.)
(2) Sensitizer CQ: camphorquinone (manufactured by Tokyo Chemical Industry Co., Ltd.).

1-3. Filler (1) Acid/Basic Filler As the acid/basic filler, F1, F2 and F3 (all manufactured by SCHOTT AG) made of composite oxides having the compositions shown in Table 3 were used. The composition of each oxide-based filler shown in Table 3 is based on the results of fluorescent X-ray measurement, and the content of each element (B-element, N-element and A-element) is expressed based on the mass standard of the oxide of each element. The pH of the basic region and the pH of the acidic region shown in Table 3 are based on the results of preparing a plurality of samples in which 1 g of filler powder is suspended in 3 ml of toluene dehydrated by a molecular sieve, as described above, dropping 0.3 ml of a 1 mass % toluene solution of a Hammett indicator having each color change pKa for each sample, shaking the suspension, and visually checking the presence or absence of a color change in the suspension to confirm the presence or absence of an acid/basic site. Furthermore, the average primary particle system of each filler and the refractive index for sodium d line at 25 ° C. are as shown below.
F1: average primary particle size 4000 nm, refractive index 1.58
F2: average primary particle size 400 nm, refractive index 1.52
F3: average primary particle size 400 nm, refractive index 1.52.

(2) Fillers other than acid/base fillers (other fillers)
(2-1) Other oxide-based fillers As oxide-based "other fillers", RF1 to RF6 (all manufactured by SCHOTT AG) and RF7 (prepared by the sol-gel method) made of composite oxides having the compositions shown in Table 3, as well as SiO ₂ : silica (prepared by the melting method with an average primary particle diameter of 1000 nm and a refractive index of 1.46) and Al ₂ O ₃ : alumina (manufactured by Tokyo Chemical Industry Co., Ltd.) were used. Note that RF2-ST is RF2 surface-treated with methacrylate-3-(trimethoxysilyl)propyl-3-(methacryloyloxy)propyltrimethoxysilane, which is a silane coupling agent. In addition, the content of F in RF5 is not based on the oxide but on the mass of the element.

The average primary particle diameters of RF1 to RF7 and their refractive indices at 25° C. for sodium d-line are shown below.
RF1: average primary particle size 1500 nm, refractive index 1.53
RF2: average primary particle size 260 nm, refractive index 1.52
RF3: average primary particle size 700 nm, refractive index 1.52
RF4: average primary particle size 700 nm, refractive index 1.53
RF5: average primary particle size 700 nm, refractive index 1.53
RF6: average primary particle size 1000 nm, refractive index 1.55
RF7: average primary particle size 260 nm, refractive index 1.52.

(2-2) Other inorganic salt and organic salt-based fillers As inorganic salt-based and organic salt-based "other fillers", the following were used as shown in Table 3: NaF: sodium fluoride (manufactured by Tokyo Chemical Industry Co., Ltd.), Na ₂ CO ₃ : sodium carbonate (manufactured by Tokyo Chemical Industry Co., Ltd.), Na ₂ SO ₄ : sodium sulfate (manufactured by Tokyo Chemical Industry Co., Ltd.), and DBS-Na: sodium dodecylbenzenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.).

2. Evaluation method of cationically polymerizable curable composition 2-1. Curability evaluation The cationically polymerizable curable composition prepared in each Example and Comparative Example was filled into a polypropylene mold with an inner diameter of 0.7 cm and a depth of 0.1 cm. Then, using a dental light irradiator (TOKUSO POWER LITE, manufactured by Tokuyama Corporation), light was irradiated for 20 seconds at an irradiation distance of 0.5 cm. At this time, the composition that was fully cured as a whole after irradiation was marked with ◯, and the composition that had uncured parts or was not cured at all was marked with ×.

2-2 Storage Stability Evaluation (1) Storage days until gelation The compositions prepared in each Example and Comparative Example were stored in a thermostatic chamber at 50°C under light-shielded conditions. The curable compositions were taken out of the thermostatic chamber every other day and allowed to cool to room temperature in a dark place, after which the properties of the curable compositions were inspected with a plastic spatula. In this case, the number of days at which the composition lost a great deal of fluidity and increased in viscosity or became jelly-like without flowing when touched with a spatula, compared to the composition immediately after preparation, was recorded as the number of days of storage until gelation (number of days to gelation).

(2) Curability after storage The curability of the composition stored in the same manner as in (1) was examined by the method shown in 2-1. The number of days when it became x was recorded as the number of days of storage until the curability decreased (number of days for which the curability decreased).

(3) Storage period The shorter of (1) or (2) was regarded as the storage period.

Example 1
To 100 parts by mass of cationic polymerizable monomer consisting of 70 parts by mass of EP-1 and 30 parts by mass of OX-1, 1.5 parts by mass of DPIB and 0.3 parts by mass of CQ were added as a polymerization initiator, and the mixture was stirred for 6 hours to prepare a liquid composition. To this liquid composition, 150 parts by mass of F1 was added as a filler to 100 parts by mass of cationic polymerizable monomer, and mixed in an agate mortar, and the mixture was evacuated and degassed to remove air bubbles, to obtain a paste-like cationic polymerizable curable composition.

The curability and storage stability of the resulting cationic polymerizable curable composition were evaluated. The results are shown in Table 4.

Examples 2 to 6, Comparative Examples 1 to 17
A cationically polymerizable curable composition was prepared in the same manner as in Example 1, except that the filler to be blended was changed as shown in Table 4, and the curability and storage stability of the composition were evaluated. The results are also shown in Table 4.

As shown in Table 4, in Comparative Example 1, which did not contain an acidic/basic filler or other fillers, the initial curing properties were good, and the number of days to gel was 39 days. On the other hand, in Examples 1 to 6, which contained an acidic/basic filler, the initial curing properties were excellent, and further, the number of days to gel was 140 days or more, which was significantly longer than that of Comparative Example 1, and the number of days until the curing properties decreased was also extremely long, at 172 days or more.
In contrast, in Comparative Examples 2 to 5, in which RF1 and RF2, which are not acidic or basic fillers, were added, the gelation period was shorter than that of Comparative Example 1, even though they were the same B-N-A composite oxide. Similarly, in Comparative Examples 6 to 12, in which "other fillers" of composite oxides other than B-N-A composite oxides and silica were added, the gelation period was shorter than that of Comparative Example 1. In Comparative Example 13, in which alumina was added, the gelation period was longer than that of Comparative Example 1, but the extent of the gelation period was inferior to that of the Examples, and the number of days until the hardening property decreased (42 days) was also significantly shorter than that of the Examples. Furthermore, in Comparative Examples 14 to 17, in which "other fillers" of inorganic salts and organic salts were added, the gelation period was longer, but the number of days until the hardening property decreased was 30 days to 2 days, which is significantly shorter (inferior) than that of the Examples, probably because these fillers have basicity.

Examples 7 to 12, Comparative Examples 18 to 20
Compositions were prepared in the same manner as in Example 1, except that the type and amount of filler used in Example 1 were changed as shown in Table 5, and their curability and storage stability were evaluated. The results are also shown in Table 5.

As shown in Table 5, the cationic polymerizable curable compositions of Examples 7 to 12, which are formulated in combination with an acidic/basic filler and a non-basic filler, also have improved storage life compared to Comparative Example 1, which does not contain an acidic/basic filler or other fillers. In addition, the storage life is significantly longer than that of Comparative Examples 18 to 20, which do not contain an acidic/basic filler and are formulated with a non-basic filler at the same filling rate as each Example.

Claims (6)

A cationically polymerizable curable composition comprising a cationically polymerizable monomer, a filler, and an iodonium salt-based photoacid generator and/or a sulfonium salt-based photoacid generator,
The filler includes an acid-base filler made of a powder of a composite oxide of a B-element, which is defined as an element capable of forming a basic oxide having an electronegativity of less than 2.0, an N-element, which is defined as an element capable of forming a neutral oxide having an electronegativity of 2.0 to 2.8, and an B-element, which is defined as an element capable of forming an acidic oxide having an electronegativity of more than 2.8;
when the abundance ratios of the B-element, the N-element and the A-element in the composite oxide are expressed as the ratio of the mass of the basic oxide:B and the mass of the acidic oxide:A based on the mass of the intermediate oxide:N, the abundance ratios are B/N=0.03 to 3.0 and A/N=1.9 to 3.0,
The composite oxide powder constituting the acid-base filler is
a basic region that has basic sites on its surface and undergoes a color change when contacted with a Hammett indicator having a color change pKa in the range of 7.2 to less than 9.3;
an acidic region , which has acidic sites on its surface and undergoes a color change when contacted with a Hammett indicator having a color change pKa in the range of greater than pKa 3.3 to 4.8;
having
The content of the acidic/basic filler is 10 to 400 parts by mass based on 100 parts by mass of the cationic polymerizable monomer.
A cationically polymerizable curable composition comprising: The cationically polymerizable curable composition according to claim 1, wherein the element capable of forming an oxide having an electronegativity of less than 2.0 is at least one selected from the group consisting of Cs, K and Na, the element capable of forming an oxide having an electronegativity of 2.0 to 2.8 is at least one selected from the group consisting of Ba, Sr, Ca, Mg, Zn, Li, Al and Zr, and the element capable of forming an oxide having an electronegativity of more than 2.8 is at least one selected from the group consisting of La, B, Ta, Si, Rh and P. the filler includes a non-basic filler made of a powder of a substance that does not have a region exhibiting a basicity of pKa 7.2 or more, and the content of the non-basic filler is 1 to 380 parts by mass relative to 100 parts by mass of the cationic polymerizable monomer;
The cationically polymerizable curable composition according to claim 1 or 2 . The cationically polymerizable curable composition according to any one of claims 1 to 3, wherein the average primary particle size of the acidic/basic filler is 10 to 1000 nm, and the refractive index of the composite oxide constituting the acidic/basic filler at 25°C is 1.45 to 1.60 with respect to sodium d line. The cationically polymerizable curable composition according to any one of claims 1 to 4 , wherein the cationically polymerizable monomer is an epoxy compound. A dental hardenable composition comprising the cationically polymerizable hardenable composition according to any one of claims 1 to 5 .