JP7658536B2 - Chemical polymerization initiator, adhesive composition, and kit for preparing adhesive composition - Google Patents

Description

The present invention relates to a chemical polymerization initiator, an adhesive composition, and a kit for preparing an adhesive composition.

In the dental field, radical polymerization curable compositions in which a polymerization initiator is mixed with a radical polymerizable monomer such as (meth)acrylate are used in various materials such as bonding materials, resin cements, resin-reinforced glass ionomers, and composite resins. When these materials are used in applications where they cannot be exposed to light or heat stimuli, chemical polymerization initiators are often used as the polymerization initiator.

Among dental materials, adhesive compositions such as bonding materials and resin cements often use acidic monomers mixed with non-acidic monomers to enhance adhesion, and so a chemical polymerization initiator that exhibits high polymerization activity in the presence of an acid (acidic monomer) has been sought. Chemical polymerization initiators that exhibit high polymerization activity in the presence of an acid are known to be those that combine an oxidizing agent made of an organic peroxide with high thermal stability, such as hydroperoxides, ketone peroxides, peroxy esters, and diacyl peroxides, with a reducing agent made of an amine, a sulfinic acid compound, a thiourea compound, an oxime compound, a transition metal compound, and the like (these may function as reducing agents alone or in combination with a plurality of them, and are sometimes collectively referred to as polymerization accelerators) (see Patent Documents 1 and 2).

Among these, chemical polymerization initiators that combine hydroperoxides and thiourea compounds have high storage stability and exhibit high activity in the presence of acid, and are therefore particularly suitable for use as chemical polymerization initiators for dental applications. By selecting a specific compound as the thiourea compound or by combining it with a polymerization accelerator other than thiourea compounds, such as a copper compound, it is possible to impart various characteristics to the thiourea compound.

When the chemical polymerization initiator comes into contact with an oxidizing agent and a reducing agent in the presence of a radical polymerizable monomer, a radical polymerization reaction is immediately initiated. Therefore, when storing (preserving) an adhesive radical polymerization curable composition (adhesive composition) containing these chemical polymerization initiators and an acidic monomer and a non-acidic monomer, it is common to prepare a combination of two or more compositions (hereinafter sometimes referred to as "partial compositions") in which each component, such as a divided polymerizable monomer component, and each component of the divided chemical polymerization initiator are mixed so that the oxidizing agent and the reducing agent do not coexist, and store (preserve) each of these partial compositions (in separate packages). Then, immediately before use, the two or more partial compositions stored in separate packages are mixed to prepare a curable composition containing all the chemical polymerization initiator components. As a result, the chemical polymerization initiator functions at the same time as mixing, and the curable composition polymerizes and hardens.

In the partial compositions in the above-mentioned separately packaged state, it is important that each partial composition has high storage stability, and some of the above-mentioned adhesive compositions are known to have both high curability and high storage stability. For example, Patent Document 3 describes a method of using a highly active "chemical polymerization initiator that contains (a) a thiourea compound, (b) a peroxy ester, (c) a divalent copper compound, and (d) an aryl borate compound and does not substantially contain hydroperoxide" (hereinafter simply referred to as a "peroxy ester-based chemical polymerization initiator") as a chemical polymerization initiator, and dividing each component constituting the peroxy ester-based chemical polymerization initiator into two compositions (hereinafter sometimes referred to as "partial initiator compositions") that are maintained in a state in which they cannot chemically contact each other, to produce the partial composition. It is described that when preparing the above, the storage stability of each of the partial compositions can be increased by packaging a first partial composition containing the (a) thiourea compound and the (d) aryl borate compound as main components and substantially free of organic peroxides, and a second partial composition containing the (b) peroxy ester, the (c) divalent copper compound, and an acidic group-containing polymerizable monomer as main components and substantially free of (b) hydroperoxides into a kit and mixing the kits at the time of use.

JP 2017-088637 A International Publication WO2017/098724 Brochure International Publication WO2019/131094 Brochure JP 2020-111513 A

However, although the adhesive composition prepared using the kit disclosed in Patent Document 3 exhibits high adhesive performance when used in the absence of water, it tends to have insufficient adhesive strength when applied as a dental cement to dentin, which contains a large amount of water (see Patent Document 4). The adhesive composition disclosed in Patent Document 4 uses a peroxyester-based chemical polymerization initiator mixed with an inorganic peroxide as a chemical polymerization initiator to improve adhesive strength in the presence of water, but with regard to adhesion to dentin, the adhesiveness is not necessarily sufficient, and there is room for further improvement, presumably because dentin contains a large amount of oxygen, and the reducing agent is consumed due to the presence of the oxidizing components generated by the oxygen.

The present invention aims to provide an adhesive radical polymerization curable composition that contains an acidic monomer and a non-acidic monomer and a chemical polymerization initiator, which exhibits curability and high storage stability equal to or greater than those of a composition containing a peroxyester-based chemical polymerization initiator, and which can exhibit excellent adhesive properties even when used in a system that contains a large amount of water or oxidizing components, particularly when used on dentin.

The above object can be achieved by the present invention, which is described below. That is, a first aspect of the present invention is a chemical polymerization initiator that contains (a) a thiourea compound, (b) a peroxy ester, (c) a divalent copper compound, (d) an aryl borate compound, and (e) a sulfite, and is substantially free of hydroperoxide, and is represented by general formula (1) described below.

The chemical polymerization initiator of the above form (hereinafter also referred to as the "chemical polymerization initiator of the present invention") preferably further contains (f) an inorganic peroxide, since a synergistic effect can be obtained. In addition, the sulfite (e) is preferably sodium sulfite.

The second aspect of the present invention is an adhesive composition that contains a radical polymerizable monomer component consisting of (g) an acidic group-containing polymerizable monomer and (h) an acidic group-free polymerizable monomer, as well as the chemical polymerization initiator of the present invention, and is substantially free of hydroperoxide.

The adhesive composition of the above form (hereinafter also referred to as the "adhesive composition of the present invention") preferably further contains (i) a filler, and is preferably a dental adhesive composition.

The third embodiment of the present invention is a kit for preparing the adhesive composition of the present invention, which is composed of a combination of a first partial composition and a second partial composition packaged in a state in which they cannot physically come into contact with each other, the first partial composition contains the (a) thiourea compound, the (d) aryl borate compound, and the (e) sulfite, and is substantially free of the (c) divalent copper compound, the (g) acidic group-containing polymerizable monomer, and peroxide {the peroxide includes the (b) peroxy ester and (f) inorganic peroxide. }, the second partial composition contains the (b) peroxy ester, the (c) divalent copper compound, and the (g) acidic group-containing polymerizable monomer, and is substantially free of the (a) thiourea compound, the (d) aryl borate compound, and the (e) sulfite, and at least one of the compositions selected from the first partial composition and the second partial composition further contains the (h) acidic group-free polymerizable monomer.

In the adhesive composition preparation kit of the above form (hereinafter also referred to as the "kit of the present invention"), it is preferable that at least one of the compositions selected from the first partial composition and the second partial composition further contains (i) a filler.

The chemical polymerization initiator of the present invention exhibits high activity even in the presence of an acid (acidic monomer) like the conventional peroxyester-based chemical polymerization initiator not containing (e) sulfite, and when it is mixed with an acidic monomer and a non-acidic monomer to form the adhesive composition of the present invention (adhesive radical polymerization curable composition), the adhesive composition of the present invention can be highly cured and can be packaged and stably stored (preserved) for a long period of time. Furthermore, by using the chemical polymerization initiator of the present invention, high adhesion can be obtained even when used in a system containing a large amount of water or oxidizing components (especially when used on dentin) compared to adhesive radical polymerization curable compositions containing conventional peroxyester-based chemical polymerization initiators.

It is noted that Patent Document 4 describes that the same effect as the present invention can be obtained by adding an inorganic peroxide to a peroxyester-based chemical polymerization initiator containing the above-mentioned (a) to (d). However, it has now been revealed for the first time that the above-mentioned effect can be obtained by adding (e) a sulfite without adding an inorganic peroxide, and that a synergistic effect, i.e., higher adhesion to dentin, can be obtained when a sulfite and an inorganic peroxide are used in combination.

The chemical polymerization initiator and adhesive composition of the present invention are characterized in that (e) a sulfite is blended with the conventional peroxyester-based chemical polymerization initiator and adhesive composition (containing the initiator) described in Patent Document 3, respectively, thereby achieving the above-mentioned effects. The kit of the present invention is characterized in that (e) a sulfite is blended with the first partial composition in the kit described in Patent Document 3.

(e) The reason why the incorporation of sulfite improves adhesion in environments with relatively large amounts of water and oxidizing components while maintaining the characteristics of conventional peroxyester-based chemical polymerization initiators is not entirely clear, and although the present invention is not bound by any logic, the inventors presume that the reason is as follows.

That is, when used in an environment in which there is no water or oxidizing components or the amount of water or oxidizing components present is extremely small, the thiourea compound, like a conventional peroxyester-based chemical polymerization initiator, comes into contact with a divalent copper compound, coordinates with the divalent copper atom constituting the divalent copper compound, and simultaneously reduces the divalent copper atom to a monovalent state. Next, a highly active (easily generates radicals) activated complex is formed by contacting the copper complex obtained by this reduction reaction with a peroxyester, and this acts together with an aryl borate compound having a curing-accelerating function to advance the curing reaction. At this time, the monovalent copper atom is oxidized again to a divalent state by a redox reaction accompanied by radical generation (catalytically without being deactivated or consumed), and the circulation process is repeated, so it is believed that high polymerization activity can be obtained.

On the other hand, in an environment where water and oxidizing components are present in relatively large amounts , when (e) sulfite is not included (when a conventional peroxyester-based chemical polymerization initiator is used), the hydrophilicity of each chemical polymerization initiator component is insufficient, so that it is insufficient at the bonding site and is easily inhibited by oxidizing components, and the above mechanism does not work easily (the above catalytic cycle does not work easily), resulting in a decrease in polymerization activity. In contrast, by adding a sulfite, which is very hydrophilic and not easily inhibited by oxidizing components, the above catalytic cycle works well, and it is believed that the adhesion is improved.

The chemical polymerization initiator of the present invention, the adhesive composition of the present invention, and the kit of the present invention are not particularly different from those described in Patent Document 3, except for the incorporation of (e) a sulfite salt (in the first partial composition), but the present invention will be described below, including these points.

In this specification, unless otherwise specified, the notation "x~y" using the numerical values x and y means "greater than or equal to x and less than or equal to y." In such a notation, when a unit is added only to the numerical value y, the unit is also applied to the numerical value x. In addition, in this specification, the term "(meth)acrylic" means both "acrylic" and "methacrylic." Similarly, the term "(meth)acrylate" means both "acrylate" and "methacrylate," and the term "(meth)acryloyl" means both "acryloyl" and "methacryloyl."

1. Chemical Polymerization Initiator of the Present Invention The chemical polymerization initiator of the present invention is characterized by comprising (a) a thiourea compound, (b) a peroxy ester, (c) a divalent copper compound, (d) an aryl borate compound, and (e) a sulfite, all of which are represented by general formula (1) described below, and being substantially free of hydroperoxide.

Here, "substantially free of hydroperoxide" means (1) no hydroperoxide (hydroperoxide content is 0 mass%), or (2) (b) the molar ratio of peroxyester (PE) to hydroperoxide (HP): HP/PE is in the range of more than 0 and not more than 2/100, preferably more than 0 and not more than 1/300. If the chemical polymerization initiator of the present invention does not satisfy the condition of "substantially free of hydroperoxide", it is difficult to increase the storage stability when the adhesive composition containing the radical polymerizable monomer component consisting of (g) acidic group-containing polymerizable monomer and (h) acidic group-free polymerizable monomer, and the chemical polymerization initiator is packaged into a kit by dividing it into a plurality of partial compositions.

The following provides a detailed explanation of the (a) thiourea compound, (b) peroxy ester, (c) divalent copper compound, (d) aryl borate compound, and (e) sulfite used in the chemical polymerization initiator of the present invention.

<(a) Thiourea Compound>
The thiourea compound refers to a compound having a =N-C(=S)-N= structure. In the chemical polymerization initiator of the present invention, a thiourea compound represented by the following general formula (1) is used as the thiourea compound .

In the general formula (1), R ¹ , R ² and R ³ each represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted acyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted alkenyl group, and R ² may be bonded to any group selected from R ¹ and R ³ to form a ring.

Among the thiourea compounds represented by the general formula (1), from the viewpoint of storage stability, it is preferred that at least two of R ¹ , R ² and R ³ are hydrogen atoms and the remaining group is the above group other than a hydrogen atom. Particularly preferred is a thiourea compound in which R ² and R ³ are hydrogen atoms and R ¹ is an acyl group.

Suitable thiourea compounds include thiourea, methylthiourea, ethylthiourea, n-propylthiourea, isopropylthiourea, cyclohexylthiourea, benzylthiourea, phenylthiourea, acetylthiourea, benzoylthiourea, adamantylthiourea, 1-(2-pyridyl)-2-thiourea, 1-(2-tetrahydrofurfuryl)-2-thiourea, N,N'-dimethylthiourea, N,N'-diethylthiourea, N,N'-di-n-propylthiourea, N, Examples of suitable thiourea compounds include N'-diisopropylthiourea, N,N'-dicyclohexylthiourea, N,N'-diphenylthiourea, trimethylthiourea, triethylthiourea, tri-n-propylthiourea, triisopropylthiourea, tricyclohexylthiourea, tetramethylthiourea, tetraethylthiourea, tetra-n-propylthiourea, tetraisopropylthiourea, tetracyclohexylthiourea, ethylenethiourea, and 4,4'-dimethylethylenethiourea. Specific examples of the most suitable thiourea compounds include acetylthiourea and benzoylthiourea.

In addition, only one type of thiourea compound may be used, or two or more types may be used in combination. When two or more types of thiourea compounds are used, the reference mass is the total mass of those thiourea compounds.

In the chemical polymerization initiator of the present invention, the amount of the thiourea compound (a) is not particularly limited, but is preferably 4 to 4,800 parts by mass per 100 parts by mass of the peroxyester (b). By satisfying this range, high polymerization activity and high storage stability can be exhibited. In order to exhibit higher polymerization activity and higher storage stability, it is more preferable to use 13 to 875 parts by mass, and even more preferable to use 27 to 600 parts by mass, per 100 parts by mass of the peroxyester.

<(b) Peroxyester>
(b) Peroxy ester is a compound having a structure represented by R-C(=O)-O-O-R' (wherein R and R' are any organic groups) or R-O-C(=O)-O-O-R' (wherein R and R' are any organic groups). In the chemical polymerization initiator of the present invention, peroxy esters having such structures can be used without any particular limitation. Specific examples of peroxyesters that can be suitably used include cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxydecanoate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl 2,5-di(2-ethylhexanoylperoxy)hexane, t-hexyl peroxy-2-ethylhexanoate, and t-butyl peroxypivalate. Examples of peroxyalkyl groups include t-butylperoxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-di(benzoylperoxy)hexane, t-butylperoxyacetate, t-butylperoxy-3-methylbenzoate, and t-butylperoxybenzoate. Among these, from the viewpoints of polymerization activity and storage stability, peroxyesters having a 10-hour half-life temperature of 80° C. or higher are preferably used, and t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxy-2-ethylhexylmonocarbonate, t-butylperoxyacetate, t-butylperoxybenzoate, etc. are particularly preferably used.

The (b) peroxyester may be used alone or in combination of two or more. When two or more (b) peroxyesters are used, the reference mass is the total mass of the (b) peroxyesters.

<(c) Divalent Copper Compound>
In the chemical polymerization initiator of the present invention, a divalent copper compound is used as the copper compound. In addition, in the chemical polymerization initiator of the present invention, a monovalent copper compound can also be used in combination with the divalent copper compound, but from the viewpoint of storage stability, it is preferable that the monovalent copper compound is contained in the chemical polymerization initiator of the present invention only in a small amount to the extent that the storage stability is not affected, or is not substantially contained. In this case, it is particularly preferable that the monovalent copper compound is not substantially contained in the second partial initiator composition. When a monovalent copper compound is contained in the second partial initiator composition, the monovalent copper compound acts as a reducing agent for the peroxyester, and the storage stability may be deteriorated.

(c) The divalent copper compound may be a hydrate or anhydrous. Examples of divalent copper compounds that can be suitably used include copper(II) chloride, copper(II) sulfate pentahydrate, copper(II) nitrate, copper(II) trifluoromethane sulfate, copper(II) acetate monohydrate, copper(II) acetylacetonate, copper(II) naphthenate, copper(II) salicylate, copper(II) benzoate, copper(II) methacrylate, copper(II) butyl phthalate, copper(II) gluconate, dichloro(1,10-phenanthroline)copper(II), ethylenediaminetetraacetate copper(II) disodium tetrahydrate, copper(II) dimethyldithiocarbamate, copper(II) diethylthiocarbamate, copper(II) hexafluoroacetylacetonate, bis(1,3-propanediamine)copper(II) dichloride, bis(8-quinolinolato)copper(II), and the like. These divalent copper compounds may be used alone or in combination of two or more.

Among these divalent copper compounds, the ligand coordinated to the divalent copper atom constituting the divalent copper compound is preferably (i) a halogen atom, (ii) an atomic group containing an oxygen atom, or (iii) an atomic group containing a nitrogen atom, in view of the high storage stability and (b) high activity with the thiourea compound. In particular, the ligand is more preferably (ii) an atomic group containing an oxygen atom, and examples of divalent copper compounds having such a ligand include copper(II) sulfate, copper(II) acetate monohydrate, and copper(II) acetylacetonate. Note that when the (ii) ligand is an atomic group containing an oxygen atom, the atomic group containing an oxygen atom coordinates to the divalent copper atom via the oxygen atom, and when the (iii) ligand is an atomic group containing a nitrogen atom, the atomic group containing a nitrogen atom coordinates to the divalent copper atom via the nitrogen atom.

In the chemical polymerization initiator of the present invention, the amount of the divalent copper compound (c) (total amount when two or more compounds are included) is not particularly limited, but is preferably 0.002 to 250 parts by mass per 100 parts by mass of the peroxyester (b). By satisfying this range, high polymerization activity and high storage stability can be exhibited. In order to exhibit higher polymerization activity and higher storage stability, it is more preferable to set it to 0.008 to 20 parts by mass, and even more preferable to set it to 0.03 to 8 parts by mass, per 100 parts by mass of the peroxyester.

<(d) Aryl borate compound>
The aryl borate compound is not particularly limited as long as it is a compound having at least one boron-aryl bond in the molecule, but it is preferable to use a compound represented by the following general formula (2).

In general formula (2), R ¹⁰ , R ²⁰ and R ³⁰ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted alkenyl group, R ⁴⁰ and R ⁵⁰ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group, and L ⁺ is a metal cation, a quaternary ammonium ion, a quaternary pyridinium ion, a quaternary quinolinium ion, or a phosphonium ion.

In addition, the L ⁺ in the general formula (2) may be a metal cation, a quaternary ammonium ion, a quaternary pyridinium ion, a quaternary quinolinium ion, or a phosphonium ion.Here, (i) the metal cation is preferably an alkali metal cation such as sodium ion, lithium ion, or potassium ion, or (ib) an alkaline earth metal cation such as magnesium ion; (ii) the quaternary ammonium ion is preferably a tetrabutylammonium ion, a tetramethylammonium ion, or a tetraethylammonium ion; (iii) the quaternary pyridinium ion is preferably a methylpyridinium ion, an ethylpyridinium ion; (iv) the quaternary quinolinium ion is preferably a methylquinolinium ion, an ethylquinolinium ion, or a butylquinolinium ion; (v) the phosphonium ion is preferably a quaternary phosphonium ion such as a tetrabutylphosphonium ion or a methyltriphenylphosphonium ion.

Suitable examples of the arylborate compound represented by the general formula (2) include sodium salt, lithium salt, potassium salt, triethanolammonium salt, and tetrabutylammonium salt of tetraphenylborate, and among these, sodium salt of tetraphenylborate is particularly preferred because it has high water solubility and therefore high curing activity in areas with a large amount of water.

In the chemical polymerization initiator of the present invention, the amount of the aryl borate compound (e) is not particularly limited, but is preferably 10 to 2000 parts by mass, and more preferably 30 to 1000 parts by mass, per 100 parts by mass of the peroxy ester (b). By using an amount in this range, high curability and/or adhesion can be obtained when the chemical polymerization initiator of the present invention is used in an adhesive composition or adhesive composition kit.

<(e) Sulfite>
(e) As the sulfite, known sulfites such as sodium sulfite, calcium sulfite, etc. can be used without any particular limitation. From the viewpoints of polymerization activity and ease of handling, it is preferable to use sodium sulfite.
The blending amount of the (e) sulfite in the chemical polymerization initiator of the present invention is preferably 7 to 21,000 parts by mass, particularly 17 to 3,300 parts by mass, and most preferably 55 to 1,320 parts by mass, per 100 parts by mass of the (b) peroxy ester, because this allows the sulfite to exhibit high polymerization activity and high adhesive strength.

The chemical polymerization initiator of the present invention may contain (f) inorganic peroxides and other polymerization accelerators in addition to the components (a) to (e). These will be explained below.

<(f) Inorganic peroxide>
As described in Patent Document 4, the inorganic peroxide (f) is known to have the same effect as the sulfite (e). With the chemical polymerization initiator of the present invention, the above effect can be obtained without using the inorganic peroxide (f). Therefore, from the viewpoint of reducing the number of components as much as possible and reducing costs (cost-effectiveness), the chemical polymerization initiator of the present invention may be substantially free of the inorganic peroxide (f). However, since a synergistic effect can be expected by using the inorganic peroxide in combination with the inorganic peroxide (f), it is preferable to actively add the inorganic peroxide.

(f) As the inorganic peroxide, known inorganic peroxides such as lithium peroxide, potassium peroxide, magnesium peroxide, calcium peroxide, barium peroxide, zinc peroxide, peroxodisulfate, peroxodiphosphate, etc. can be used without any particular limitation. From the viewpoint of polymerization activity, it is preferable to use peroxodisulfate such as sodium peroxodisulfate, potassium peroxodisulfate, ammonium peroxodisulfate, etc., and it is particularly preferable to use potassium peroxodisulfate or sodium peroxodisulfate.
When the inorganic peroxide (f) is actively blended with the chemical polymerization initiator of the present invention, the blending amount is preferably 7 to 21,000 parts by mass, particularly 17 to 3,300 parts by mass, and most preferably 55 to 1,320 parts by mass, per 100 parts by mass of the peroxy ester (b), because high polymerization activity and high adhesive strength can be exhibited.

<Other Polymerization Accelerators>
The chemical polymerization initiator of the present invention may be mixed with an aromatic sulfinic acid compound and a barbituric acid compound as other polymerization accelerators.

Examples of aromatic sulfinic acid compounds that can be suitably used include sodium p-toluenesulfinate, sodium benzenesulfinate, 2,4,6-trimethylbenzenesulfinic acid, 2,6-dimethylbenzenesulfinic acid, 2,6-diisopropylbenzenesulfinic acid, 2,4,6-trimethylbenzenesulfinic acid, and the sodium salts, triethanolammonium salts, and tetraethylammonium salts of 2,4,6-triisopropylbenzenesulfinic acid. Among these aromatic sulfinic acid salts, benzenesulfinic acid salts and paratoluenesulfinic acid salts are preferred because of their high reactivity and high solubility in polymerizable monomers.

Examples of suitable barbituric acid compounds include 5-butylbarbituric acid, 1,3,5-trimethylbarbituric acid, 1-cyclohexyl-5-ethylbarbituric acid, and the sodium and calcium salts of these barbituric acids.

When these are blended, the total amount of these components is preferably 10 to 2,000 parts by weight, and more preferably 30 to 1,000 parts by weight, per 100 parts by weight of (b) peroxyester.

2. Adhesive Composition of the Present Invention The adhesive composition of the present invention is characterized in that it contains a radical polymerizable monomer component consisting of (g) an acidic group-containing polymerizable monomer and (h) an acidic group-free polymerizable monomer, as well as the chemical polymerization initiator of the present invention, and is substantially free of hydroperoxide. Here, "substantially free of hydroperoxide" means (1) the case where no hydroperoxide is contained (the content of hydroperoxide is 0 mass%), or (2) the molar ratio of (b) peroxyester (PE) to hydroperoxide (HP) contained in the adhesive composition of the present invention: HP/PE, is in the range of more than 0 and not more than about 2/100, preferably more than 0 and not more than about 1/300.

The mixing ratio of the (g) acidic monomer and the (h) non-acidic monomer in the radical polymerizable monomer component of the adhesive composition of the present invention is preferably such that the (g) acidic group-containing polymerizable monomer and the (h) non-acidic group-containing polymerizable monomer are 0.1 to 50 parts by mass per 100 parts by mass of the radical polymerizable monomer component, with the remainder being the (h) non-acidic group-containing polymerizable monomer, and more preferably such that the (g) acidic group-containing polymerizable monomer is 1 to 30 parts by mass per 100 parts by mass of the radical polymerizable monomer component, with the remainder being the (h) non-acidic group-containing polymerizable monomer. In addition, the content of the chemical polymerization initiator of the present invention is preferably such that the (b) peroxyester is 0.005 to 5 parts by mass, particularly the (b) peroxyester is 0.05 to 2.5 parts by mass, per 100 parts by mass of the radical polymerizable monomer component.

The adhesive composition of the present invention may further contain (i) a filler, a solvent, a polymerization inhibitor, a pigment, an ultraviolet absorber, etc., as necessary. The adhesive composition of the present invention can be suitably used as a dental material, and among dental materials, it can be particularly suitably used as a dental cement or a dental adhesive. When used as a dental cement, it is preferable that the adhesive composition contains (i) a filler, and when used as a dental adhesive, it is preferable that the adhesive composition contains a solvent.

Hereinafter, the radical polymerizable monomers used in the adhesive composition of the present invention, specifically (g) acidic group-containing polymerizable monomers (acidic monomers) and (h) acidic group-free polymerizable monomers (non-acidic monomers), as well as (i) fillers, will be described.

<(g) Acidic Group-Containing Polymerizable Monomer (Acidic Monomer)>
As the acidic monomer, a known polymerizable monomer having at least one acidic group and at least one radically polymerizable unsaturated group can be used. Here, the acidic group is one that causes an aqueous solution or water suspension of the radically polymerizable monomer having this group to exhibit acidity, and representative examples include those having a hydroxyl group such as a carboxyl group (-COOH), a sulfo group (-SO ₃ H), a phosphinico group {=P(=O)OH}, and a phosphono group {-P(=O)(OH) ₂ }. In addition to such hydroxyl group-containing acidic groups, examples of the acidic monomer include an acid anhydride group having a structure in which two hydroxyl group-containing acidic groups are dehydrated and condensed, and an acid halide group in which the hydroxyl group of a hydroxyl group-containing acidic group is substituted with a halogen. The radically polymerizable unsaturated group is not particularly limited, and may be a known one. Examples of such groups include (meth)acryloyl-based groups such as a (meth)acryloyl group, a (meth)acryloyloxy group, a (meth)acryloylamino group, and a (meth)acryloylthio group, a vinyl group, an allyl group, and a styryl group.

From the viewpoint of polymerization, a (meth)acrylic acid ester-based acid group-containing polymerizable monomer is preferably used as the acidic monomer. From the viewpoint of safety to living organisms, this (meth)acrylic acid ester-based acid group-containing polymerizable monomer is particularly suitable for use in dental materials. Only one type of acidic monomer may be used, or two or more types may be used in combination.

Suitable examples of acidic monomers that can be used include 2-(meth)acryloyloxyethyl dihydrogen phosphate, bis[2-(meth)acryloyloxyethyl]hydrogen phosphate, 2-(meth)acryloyloxyethylphenyl hydrogen phosphate, 6-(meth)acryloyloxyhexyl dihydrogen phosphate, 6-(meth)acryloyloxyhexylphenyl hydrogen phosphate, 10-(meth)acryloyloxydecyl dihydrogen phosphate, 1,3-di(meth)acryloylpropane-2-dihydrogen phosphate, 1,3-di(meth)acryloylpropane-2-phenyl hydrogen phosphate, and bis[5-{2-(meth)acryloyloxyethoxycarbonyl}heptyl]hydrogen phosphate.

<(h) Acidic Group-Free Polymerizable Monomer (Non-Acidic Monomer)>
The non-acidic monomer is not particularly limited as long as it has at least one radically polymerizable unsaturated group in the molecule and does not have an acidic group. From the viewpoint of polymerizability and safety to living organisms, a (meth)acrylic acid ester-based polymerizable monomer not containing an acidic group is preferably used. The non-acidic monomer may be used alone or in combination of two or more kinds. Examples of non-acidic monomers that can be preferably used include methyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 2,2-bis[4-(3-methacryloyloxy)-2-hydroxypropoxyphenyl]propane, 2,2-bis(methacryloyloxypolyethoxyphenyl)propane, 2-hydroxyethyl methacrylate, 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate, 1,10-decanediol di(meth)acrylate, and the like.

When the adhesive composition of the present invention is used as a dental material, the cured product of the adhesive composition may be required to have superior mechanical strength. In this case, it is preferable to use a di-, tri-, or tetra-functional radical polymerizable monomer having multiple radical polymerizable groups as the non-acidic monomer.

Next, compounding agents that can be suitably compounded in the adhesive composition of the present invention will be described.
<(i) Filler>
As the filler that can be used in the adhesive composition of the present invention, inorganic fillers, organic fillers, organic-inorganic composite fillers, etc. that are used in conventional dental materials, etc. can be used without any particular limitation. From the viewpoint of the mechanical strength of the cured product, it is preferable to use inorganic fillers and organic-inorganic composite fillers.

Examples of suitable inorganic fillers include various silicas; composite oxides containing silicon as a constituent element, such as silica-titania and silica-zirconia; clay minerals or silicates containing silicon as a constituent element, such as talc, montmorillonite, zeolite, and calcium silicate (hereinafter, these are referred to as silica-based fillers); ytterbium fluoride, yttrium fluoride, silicate glass, fluoroaluminosilicate glass, lanthanum glass, barium glass, strontium glass, etc. These inorganic fillers may be surface-treated with a surface treatment agent such as a silane coupling agent in order to improve compatibility with the polymerizable monomer and improve the mechanical strength and water resistance of the resulting cured body. The silica-based fillers have excellent chemical stability and are easy to surface-treat with a silane coupling agent, etc. In addition, examples of organic fillers that can be suitably used include 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, acrylonitrile-styrene-butadiene copolymer, etc. Furthermore, examples of organic-inorganic composite fillers that can be suitably used include organic-inorganic composite fillers obtained by compositing a polymerizable monomer that can be used as (e) an acidic monomer or (f) a non-acidic monomer with an inorganic filler. The compositing method is not particularly limited, and the filler may be solid or may have fine holes. From the viewpoint of the mechanical strength of the cured body, it is preferable to use an organic-inorganic composite filler in which the surface of inorganic aggregate particles is coated with an organic polymer and has fine holes, as described in the pamphlet of International Publication No. 2013/039169. Only one of these fillers may be used, or two or more of them may be used in combination. The shape of the filler is not particularly limited, and may be an irregular particle shape obtained by normal grinding, or may be spherical particles. The average particle size of the filler is not particularly limited, but is preferably about 0.01 to 100 μm, and more preferably about 0.1 to 50 μm.

(i) The total amount of the filler may be appropriately determined according to the intended use. In particular, when used in dental materials, particularly dental cement, it is preferable to mix 65 to 1000 parts by mass per 100 parts by mass of the polymerizable monomer component contained in the dental cement. From the viewpoint of kneadability and mechanical strength of the hardened body, it is more preferable to mix 150 to 400 parts by mass per 100 parts by mass of the polymerizable monomer component contained in the dental cement. In addition, when the adhesive composition of the present invention is used as a dental cement, the composition of the radical polymerizable monomer component is usually 0.1 to 50 mass% (g) acidic monomer and the remainder (h) non-acidic monomer based on the total mass of the radical polymerizable monomer component, and preferably 1 to 30 mass% (g) acidic monomer and the remainder (h) non-acidic monomer. In a dental cement using such a composition of polymerizable monomer components, the adhesion to tooth structure is stronger and the adhesion durability to tooth structure and prosthetics made of various materials can be further improved.

3. Kit of the Present Invention The kit of the present invention having the above-mentioned characteristics is composed of a combination of a first partial composition and a second partial composition packaged in a state in which they cannot physically come into contact with each other, and the adhesive composition of the present invention is prepared by mixing the two partial compositions at the time of use. The first partial composition contains the (a) thiourea compound, the (d) aryl borate compound, and the (e) sulfite, and is substantially free of the (c) divalent copper compound, the (g) acidic group-containing polymerizable monomer, and peroxide {the peroxide includes the (b) peroxy ester and the (f) inorganic peroxide.}, the second partial composition contains the (b) peroxy ester, the (c) divalent copper compound, and the (g) acidic group-containing polymerizable monomer, and is substantially free of the (a) thiourea compound, the (d) aryl borate compound, and the (e) sulfite, and at least one composition selected from the first partial composition and the second partial composition further contains the (h) acidic group-free polymerizable monomer.

The kit of the present invention having the above characteristics has high storage stability of the individually packaged first partial composition and second partial composition, and can be stably stored (preserved) in the individually packaged state for a long period of time. Not only is it useful as a storage form, but it can also be distributed on the market as a product itself.

The phrase "packaged in a state where one composition cannot come into contact with another composition" means that one composition and another composition are packaged in a state where they are separated by an inhibitor (packaging material) that inhibits molecular diffusion between the two. As the inhibitor (packaging material), a solid material such as resin, glass, metal, or ceramic, which is generally used as a material for containers or bags, is used. A typical example of a "state where one composition cannot come into contact with the other composition," for example, is a state where one type of composition is stored in a sealed state in a container that blocks outside air and outside light. Specific packaging forms include a form filled in a container such as a bottle, a tube, or a syringe. For example, the adhesive composition of the present invention can be prepared by i) applying an appropriate amount of the first agent and the second agent on a mixing paper and mixing the two with a spatula, ii) when the first agent and the second agent are in a paste form, simultaneously extruding the first agent and the second agent from a syringe with a mixing tip attached to the tip, or iii) when the first agent and the second agent are in a liquid form, collecting the first agent and the second agent in the same mixing dish.

In the first and second partial compositions, "substantially free" means (1) that the target compound or component is not contained (content is 0% by mass), or (2) that the target compound or component is contained in a small amount to the extent that no significant difference in storage stability is observed compared to the case where the target compound or component is not contained. Here, in the case shown in (2) above, the content in each partial composition is usually 1% by mass or less, preferably 0.02% by mass or less, and particularly preferably 0.01% by mass or less.

When the adhesive composition of the present invention to be prepared contains (f) an inorganic peroxide, the inorganic peroxide (f) is contained in the second partial composition and is not substantially contained in the first partial composition. When the adhesive composition of the present invention contains an aromatic sulfinic acid compound and/or a barbituric acid compound, these compounds are preferably blended in the first agent. Furthermore, when the adhesive composition of the present invention contains (i) a filler, these components may be blended in either the first agent or the second agent, but it is preferable to blend them in both agents because they blend well and can be easily homogenized when mixed.

For example, when the kit of the present invention is used as a dental cement kit, it is preferable to adopt an embodiment in which the first partial composition is composed only of (a) a thiourea compound, (d) an aryl borate compound, (e) a sulfite, (h) an acidic group-free polymerizable monomer, and (i) a filler, and the second partial composition is composed only of (b) a peroxy ester, (c) a divalent copper compound, (g) an acidic group-containing polymerizable monomer, (h) an acidic group-free polymerizable monomer, and (i) a filler, or to adopt an embodiment in which (f) an inorganic peroxide is further added to the second partial composition in the above embodiment. In these embodiments, it is preferable to use acetylthiourea or benzoylthiourea as (a) the thiourea compound, sodium salt of tetraphenylboron as (d) the aryl borate compound, sodium sulfite as (e) the sulfite, and peroxodisulfate as (f) the inorganic peroxide.

The compositions of the first partial composition (first agent) and the second partial composition (second agent) are basically determined so that when they are mixed in equal amounts {the mixing ratio of the first agent and the second agent (amount of the first agent/amount of the second agent): 1/1, or the mixing ratio of the first agent and the second agent (100 x amount of the first agent/amount of the second agent): 100%), the composition of the adhesive composition of the present invention is obtained. Then, according to the composition thus determined, the first agent and the second agent can be easily prepared by weighing and mixing each component. Note that the above "equal amount" usually means equal amount on a mass basis, but when the composition is liquid, it may also mean equal amount on a volume basis.

However, in actual use, that is, when the first partial composition (first agent) and the second partial composition (second agent) are mixed to prepare the adhesive composition of the present invention, the mixing ratio may not be strictly 1/1. In this case, it is preferable to obtain the adhesive composition of the present invention having the desired composition when mixed at a mixing ratio other than 1/1 (hereinafter also referred to as the "specified mixing ratio"). The specified mixing ratio (this value expressed as a percentage is also referred to as the "specified mixing ratio") may be appropriately determined within a range in which polymerization activity and operability are not significantly impaired. However, from the practical viewpoint of ease of handling and ease of product packaging, the specified mixing ratio (rate) is preferably within the range of 1/5 to 5/1 (mixing ratio: 20% to 500%) by mass (or volume) (first agent/second agent), and more preferably within the range of 1/3 to 3/1 (mixing ratio: 33% to 300%).

The specified mixing ratio (rate) can be displayed on a mixing ratio (rate) information display medium. Examples of this mixing ratio (rate) information display medium include i) a product package such as a paper box, ii) product instructions provided as paper media and/or electronic data, iii) containers (bottles, syringes, packaging bags, etc.) in which the first and second agents are stored in a sealed state, iv) a product catalog provided as paper media and/or electronic data, and v) correspondence sent to the product user by email, mail, etc. separately from the product. The specified mixing ratio may also be provided to the product user in a manner that allows the product user to recognize it in a manner other than those shown in i) to v) above.

When using the kit of the present invention, the mixed composition (adhesive composition of the present invention) obtained by mixing the first partial composition (first agent) and the second partial composition (second agent) contains all types of chemical polymerization initiator components and polymerizable monomer components, and therefore polymerizes and hardens quickly or with a preset operation margin. This allows a hardened body to be obtained. A known method can be used to polymerize and harden the mixed composition. For example, the mixed composition can be applied to the area that needs to be hardened and left to stand. In this case, the applied mixed composition can be kept at a temperature range of 10 to 37°C to allow the mixed composition to harden sufficiently.

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

1. Abbreviations of Substances Used First, the abbreviations of substances used in the chemical polymerization initiators and compositions containing the same in each of the Examples and Comparative Examples will be described below.

<(a) Thiourea Compound>
AcTU; acetylthiourea BzTU; benzoylthiourea PTU; pyridylthiourea.

<(b) Peroxyester>
BPT: t-butylperoxy-3,5,5-trimethylhexanoate BPB: t-butylperoxybenzoate BPE: t-butylperoxy-2-ethylhexylmonocarbonate BPL: t-butylperoxylaurate.

<(c) Divalent Copper Compound>
CuA; Copper(II) acetate monohydrate CuAA; Copper(II) acetylacetonate

<(d) Aryl borate compound>
PhBNa: sodium salt of tetraphenylboron. PhBTEOA: triethanolammonium salt of tetraphenylboron.

<(e) Sulfite>
SS; sodium sulfite.

<(f) Inorganic peroxide>
NPS: sodium peroxodisulfate KPS: potassium peroxodisulfate.

<(g) Acidic Group-Containing Polymerizable Monomer (Acidic Monomer)>
MDP: 10-methacryloxydecyl dihydrogen phosphate SPM: A mixture of 2-methacryloyloxyethyl dihydrogen phosphate and bis(2-methacryloyloxyethyl)hydrogen phosphate in a molar ratio of 1:1.

<(h) Acidic Group-Free Polymerizable Monomer (Non-Acidic Monomer)>
BisGMA; 2,2-bis[4-(3-methacryloyloxy)-2-hydroxypropoxyphenyl]propane D-2.6E; 2,2-bis(methacryloyloxypolyethoxyphenyl)propane 3G; triethylene glycol dimethacrylate HEMA; 2-hydroxyethyl methacrylate UDMA; 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate.

<(i) Filler>
F1: Silica-zirconia filler having an average particle size of 3 μm. F2: Silica-zirconia filler having an average particle size of 0.2 μm.

2. Examples 1 to 25 and Comparative Examples 1 and 2
The first agent (first partial composition) and the second agent (second partial composition) were prepared and mixed at a mass ratio of 1:1 to prepare adhesive compositions of each of the Examples and Comparative Examples, and evaluations were carried out. Note that these adhesive compositions contain a filler, and the adhesive compositions of Examples 1 to 25 can also be suitably used as dental cements.
The preparation methods of the first and second agents, the evaluation methods, and the evaluation results are described below.

2-1. Method for preparing the first and second agents First, as the polymerizable monomer component for the first agent used in Examples 1 to 8, Examples 10 to 25, and Comparative Examples 1 and 2, 50 parts by mass of a polymerizable monomer component for the first agent consisting of 30 parts by mass of (h) BisGMA and 20 parts by mass of (h) 3G were prepared, and as the polymerizable monomer component for the first agent used in Example 9, 50 parts by mass of a polymerizable monomer component for the first agent consisting of 30 parts by mass of (h) UDMA and 20 parts by mass of (h) 3G were prepared. Then, these polymerizable monomer components for the first agent: 50 parts by mass, (i) 116.5 parts by mass of a filler consisting of 46.5 parts by mass of F1 and 70 parts by mass of F2, and a first partial initiator composition having the composition shown in Table 1 were mixed to prepare a first agent.

In addition, as the polymerizable monomer component for the second agent used in Examples 1 to 8, Examples 10 to 25, and Comparative Examples 1 and 2, 50 parts by mass of a polymerizable monomer component for the second agent consisting of (g) MDP: 12.5 parts by mass, (h) HEMA: 5 parts by mass, (h) D-2.6E: 20 parts by mass, and (h) 3G: 12.5 parts by mass was prepared. In addition, as the polymerizable monomer component for the second agent used in Example 9, 50 parts by mass of a polymerizable monomer component for the second agent consisting of (g) SPM: 12.5 parts by mass, (h) HEMA: 5 parts by mass, (h) D-2.6E: 20 parts by mass, and (h) 3G: 12.5 parts by mass was prepared. Then, 50 parts by mass of these polymerizable monomer components for the second agent, (i) 116.5 parts by mass of a filler consisting of 46.5 parts by mass of F1 and 70 parts by mass of F2, and a second partial initiator composition having the composition shown in Table 1 were mixed to prepare the second agent.

The parts by mass (numbers in parentheses) of each component shown in Table 1 represent parts by mass relative to 50 parts by mass of the polymerizable monomer component for the first agent for the first partial initiator composition, and represent parts by mass relative to 50 parts by mass of the polymerizable monomer component for the second agent for the second partial initiator composition. That is, the components other than the polymerization initiator component of the first agent and the second agent in each example and comparative example are common, and the composition of the first agent and the second agent in each example and comparative example has a composition in which the first agent base composition and the second agent base composition, respectively, having the following compositions, are blended with the first partial initiator composition and the second partial initiator composition, each having the composition shown in Table 1. For example, the contents of (a), (e), and (d) in the first agent in Example 1 are, as shown in Table 1, BzTU: 0.5 parts by mass, SA: 3.3 parts by mass, and PhBNa: 1.5 parts by mass, respectively.

(1) First agent base composition - (h) BisGMA: 30 parts by mass - (h) 3G: 20 parts by mass - (i) F1: 46.5 parts by mass - (i) F2: 70 parts by mass (2) Base composition for second agent - (g) MDP: 12.5 parts by mass - (h) HEMA: 5 parts by mass - (h) D-2.6E: 20 parts by mass・(h) 3G: 12.5 parts by mass ・(i) F1: 46.5 parts by mass ・(i) F2: 70 parts by mass

2-2. Various Evaluation Methods The flexural strength and adhesive strength to dentin of the cured body of the adhesive composition obtained by mixing the first and second agents prepared as described above in a mass ratio of 1:1 were evaluated, and the adhesive strength to cobalt-chromium alloy was also evaluated for Examples 1 and 16 and Comparative Examples 1 and 2. The details of the measurement methods for the flexural strength, adhesive strength to dentin, and adhesive strength to cobalt-chromium alloy are shown below.

In each evaluation, in order to examine the storage stability of the first and second agents, two types of adhesive compositions shown in (a) and (b) below were used.
(a) "Immediately after preparation" adhesive composition: An adhesive composition consisting of a combination of a first part and a second part that has been prepared within 3 hours.
(b) Adhesive composition "after storage" The adhesive composition after storage for 2 weeks at 50°C in a state in which the first agent and the second agent constituting the adhesive composition immediately after preparation shown in (a) above were filled in separate containers.

2-2-1. Flexural strength measurement The adhesive composition prepared by the above method was filled into a polyacetal mold having a rectangular hole of 25 mm in length, 2 mm in width, and 2 mm in thickness, and left in a thermostatic chamber under humid conditions at 37°C for 60 minutes to cure. The obtained cured product was immersed in water at 37°C for 24 hours, and then burrs were removed using waterproof abrasive paper to obtain a measurement sample. Next, using a universal testing machine (AG-I type, manufactured by Shimadzu Corporation), a load was started under a crosshead speed of 1 mm/mm, and a load was applied to the test sample until the measurement sample broke, and the bending strength was calculated from the maximum load using the following formula (1). The results are shown in Table 8.
Equation (1): Bending strength (MPa) = 3 x maximum load (N) x distance between support centers / (2 x width (mm) x thickness (mm) x thickness (mm) of test piece).
In addition, this test is performed in an environment substantially free of water and oxidizing components, and therefore evaluates initiator activity in the substantial absence of water and oxidizing components.

2-2-2. Measurement of adhesive strength to dentin The extracted bovine mandibular anterior teeth were polished with #600 waterproof abrasive paper under water, and the dentin plane was cut out so as to be parallel to the labial surface. After blowing compressed air onto the dentin plane to dry it, a double-sided tape with a circular hole of 3 mm in diameter was fixed to each of them, and the adhesive area was determined. Next, the adhesive composition prepared by the above method was applied to a cylindrical metal attachment with a diameter of 8 mm, and the applied surface of the adhesive composition was pressed against the dentin surface so that the circular hole of the double-sided tape and the surface of the metal attachment were concentric. After immersing the test sample in water at 37°C for 24 hours, a universal testing machine (AG-I type, manufactured by Shimadzu Corporation) was used to start loading under the condition of a crosshead speed of 1 mm/mm, and a load was applied to the test sample until the measurement sample broke, and the adhesive strength was calculated from the maximum load using the following formula (2).
Equation (2) Adhesion strength (MPa)=maximum load (N)/adhesion area (mm ² ).

In order to demonstrate high adhesive strength to dentin, it is necessary for the portion of the adhesive composition in contact with the dentin, which contains a large amount of water and oxidizing components, and the portion that is distant from the dentin and contains almost no water or oxidizing components (the portion close to the metal attachment during testing) to polymerize sufficiently.
Therefore, this test is an evaluation of whether polymerization activity is sufficient both in a system containing a large amount of water and oxidizing components and in a system containing almost no water and oxidizing components.

2-2-3. Measurement of adhesive strength to cobalt-chromium alloy In order to more directly confirm the influence of water and oxidizing components on adhesive strength, test samples were prepared as follows for the adhesive strength to cobalt-chromium alloy for (1) a system in which water and an oxidizing component (hypochlorous acid) were not present, (2) a system in which water was present but an oxidizing component (hypochlorous acid) was not present, and (3) a system in which water and an oxidizing component were present.
(1) Water and oxidizing component-free system: A cobalt-chromium alloy plate was polished with #800 and #1500 waterproof abrasive paper under water, then subjected to high pressure sandblasting (4-5 kgf/ ^cm2 from a distance of 0.5-1 cm), and then ultrasonically cleaned twice with ion-exchanged water and once with acetone. Next, compressed air was blown onto the surface of the plate after cleaning to dry it, and a double-sided tape with a circular hole of 3 mm in diameter was fixed. Here, the area inside the circular hole of 3 mm in diameter is the adhesive area. Next, a mixed composition of the first agent and the second agent constituting the adhesive composition immediately after preparation or after storage was applied to the end face of a cylindrical metal attachment of 8 mm in diameter. Then, the circular hole of the double-sided tape and the end face of the metal attachment to which the mixed composition was applied were pressed together so that the central axes of both were aligned, to obtain a test sample.
(2) System with water present and oxidizing component absent: A double-sided tape with a circular hole of 3 mm in diameter was fixed in the same manner as above, and then a test sample was prepared in the same manner as above, except that water was applied to the inside of the hole using a cotton ball.
(3) Water and oxidizing component present system: A test sample was prepared in the same manner as above, except that a double-sided tape with a circular hole of 3 mm in diameter was fixed in place, and then a cotton ball was used to apply hypochlorous acid water to the inside of the hole.

Next, these test samples were immersed in water at 37°C for 24 hours, and then a tensile load was applied to them at a crosshead speed of 1 mm/mm using a universal testing machine (AG-I type, manufactured by Shimadzu Corporation). At this time, the tensile load applied to the test sample was gradually increased until the adhesive surface of the test sample broke, and the adhesive strength was calculated from the maximum load at which breakage occurred using the above-mentioned formula (1).
In this test, when hypochlorous acid water is applied inside the circular hole, it is evaluated whether the polymerization activity is sufficient in both systems where water and oxidizing components are present in large amounts and systems where they are almost absent. When water is applied inside the circular hole, it is evaluated whether the polymerization activity is sufficient in both systems where water is present in large amounts and systems where they are almost absent. When water is not applied inside the circular hole, it is evaluated whether the polymerization activity is sufficient in a system where there is almost no water.

2-3. Evaluation results The evaluation results are shown in Tables 2 and 3.

As shown in Table 2, the adhesive compositions of Examples 1 to 25 showed good results in both bending strength and adhesive strength to dentin both immediately after preparation and after storage. These results demonstrate that the adhesive compositions of Examples 2 to 25 also have excellent curing properties, adhesive strength, and storage stability. In particular, the adhesive compositions of Examples 16 to 23, which contain inorganic peroxides, showed even higher adhesive strength due to the synergistic effect with sulfite.

The adhesive compositions of Examples 24 and 25 are examples in which only the combinations of the main components (a) to (e) constituting the first and second agents, respectively, are changed from the adhesive composition of Example 1, and do not correspond to the kit of the present invention. Therefore, although the bending strength and adhesive strength of Examples 24 and 25 immediately after preparation are high like Example 1, the bending strength and adhesive strength after storage are lower than those of Example 1.

Comparative Examples 1 and 2 lacked sulfite, and therefore showed high bending strength, but low adhesive strength to dentin. Comparative Example 2 contained inorganic peroxide, and therefore showed higher adhesive strength than Comparative Example 1, but was lower than the example containing sulfite.

Furthermore, as shown in Table 3, Examples 1 and 16 showed high adhesive strength regardless of whether water or hypochlorous acid water was applied. These results show that the adhesive compositions of these Examples have excellent curing properties and storage stability, and furthermore, show high adhesive strength regardless of the presence of water or oxidizing components. In particular, the adhesive composition of Example 16 showed higher adhesive strength when water was applied than when water was not applied. This result is believed to be the result of the sulfite and inorganic peroxide working effectively in the areas where water is present, resulting in a synergistic effect.

On the other hand, the adhesive composition of Comparative Example 1 does not contain sulfite, so it is affected by the presence or absence of application of water or hypochlorous acid water, and the adhesive strength was significantly reduced when water or hypochlorous acid water was applied. The adhesive composition of Comparative Example 2 does not contain sulfite but contains inorganic peroxide, so it showed high adhesive strength regardless of whether water was applied, but showed low adhesive strength when hypochlorous acid water was applied.

Claims (8)

(a) a compound represented by the following general formula (1):
(In the formula, R ¹ , R ² and R ³ each represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted acyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted alkenyl group, and R ² may be bonded to any group selected from R ¹ and R ³ to form a ring.)
A thiourea compound represented by the formula :
(b) peroxy esters,
(c) a divalent copper compound,
(d) an aryl borate compound; and (e) a sulfite,
A chemical polymerization initiator that is substantially free of hydroperoxide. (f) The chemical polymerization initiator according to claim 1, further comprising an inorganic peroxide. The chemical polymerization initiator according to claim 1 or 2, characterized in that the sulfite (e) is sodium sulfite. An adhesive composition comprising a radical polymerizable monomer component consisting of (g) an acidic group-containing polymerizable monomer and (h) an acidic group-free polymerizable monomer, and the chemical polymerization initiator according to any one of claims 1 to 3, and substantially free of hydroperoxide. (i) The adhesive composition according to claim 4, further comprising a filler. The adhesive composition according to claim 4 or 5, which is a dental adhesive composition. A kit for preparing the adhesive composition according to any one of claims 4 to 6, comprising:
The present invention comprises a combination of a first partial composition and a second partial composition packaged in such a way that they cannot come into physical contact with each other;
the first partial composition contains the (a) thiourea compound, the (d) aryl borate compound, and the (e) sulfite, and is substantially free of the (c) divalent copper compound, the (g) acidic group-containing polymerizable monomer, and the (e) peroxide;
the second partial composition contains the (b) peroxy ester, the (c) divalent copper compound, and the (g) acidic group-containing polymerizable monomer, and is substantially free of the (a) thiourea compound, the (d) aryl borate compound, and the (e) sulfite;
At least one composition selected from the first partial composition and the second partial composition further contains the (h) acidic group-free polymerizable monomer.
A kit for preparing an adhesive composition comprising: The adhesive composition preparation kit according to claim 7, wherein at least one of the compositions selected from the first partial composition and the second partial composition further comprises (i) a filler.